JP6815409B2 - Raw material sheets and foamable paper containers used for foamable paper products - Google Patents

Description

The present invention relates to a raw material sheet and a foamable paper container used for a foamable paper product.

Generally, a foamable paper sheet and a foamable paper container are made by laminating low-density polyethylene on one side of a base paper and high-density or medium-density polyethylene on the other side, and heating the base paper in an oven. The surface of the low-density polyethylene has a print layer including a print pattern such as a decorative pattern, a trade name, a company name, and a barcode.

Examples of the method for forming the print layer include gravure printing and flexographic printing. It has been conventionally known that an ink for gravure printing contains a polyamide resin or the like and a cellulose derivative as a binder component. The ink for gravure printing remarkably suppresses the foaming of low-density polyethylene, and in the printed portion and the non-printed portion of the print layer, or in the printed portion and the overprinted portion in which printing is further performed on the printed portion. , There is a difference in the thickness of low density polyethylene after foaming. As a result, there is a problem that the printed portion or the overcoated portion becomes a concave portion, a step is generated, and the printing becomes unclear.

Patent Document 1 contains a colorant, a binder resin and a solvent as an ink for improving the unevenness of the surface of the printed layer, and the binder resin contains a urethane resin and a vinyl chloride / vinyl acetate copolymer. The mixing ratio of the urethane resin: vinyl chloride / vinyl acetate copolymer is 50:50 to 99: 1, and the elongation ratio of the binder resin is based on the total weight of the urethane resin and the vinyl chloride / vinyl acetate copolymer. An oil-based ink having a value of 400% to 3,000% is disclosed.

Japanese Patent No. 4619455

According to the oil-based ink described in Patent Document 1, it is possible to obtain a foamable paper product in which the surface of the low-density polyethylene after foaming is maintained in a state where the unevenness is as small as possible, the surface of the print layer is smooth, and the appearance is excellent. However, since oil-based ink uses an organic solvent, there is concern about the impact on the environment and workers. Specifically, there are problems such as a large amount of residual solvent and solvent (VOC) discharged from printed matter.

The present invention has been made in view of the above circumstances, and is a raw material sheet and the raw material sheet for obtaining a foamable paper product containing an ink having a small impact on the environment, having a smooth print layer surface, and having an excellent appearance. Provided is an effervescent paper container made of.

As a result of diligent research to achieve the above object, the present inventors have used a water-based ink containing a binder resin having a urethane resin in a specific ratio, so that the surface of the print layer is smooth and foamed with excellent appearance. We have found that a plastic paper product can be obtained, and have completed the present invention.

［２］前記水性インキが、着色剤、及びバインダー樹脂を含み、前記バインダー樹脂の樹脂固形分中、ガラス転移点が−２０℃以上３０℃以下のウレタン系樹脂を３０質量％以上含有する［１］に記載の原材料シート。
［３］前記水性インキがさらに体質顔料を含む［１］又は［２］に記載の原材料シート。
［４］前記体質顔料が二酸化ケイ素である［３］に記載の原材料シート。
［５］さらに、前記発泡層が発泡抑制部を備える［１］〜［４］のいずれか一つに記載の原材料シート。
［６］前記発泡抑制部は発泡抑制インキ塗装部を有する熱可塑性樹脂層を加熱してなり、
前記発泡抑制インキは、ガラス転移点が６０℃以上１２０℃以下の樹脂を、前記バインダー樹脂の樹脂固形分中、７０重量％以上含有する［５］に記載の原材料シート。
［７］前記ガラス転移点が６０℃以上１２０℃以下の樹脂が、アクリル系樹脂である［６］に記載の原材料シート。
［８］［１］〜［７］のいずれか一つに記載の原材料シートからなることを特徴とする発泡性紙製容器。The present invention includes the following aspects.
[1] A raw material sheet used for foamable paper products.
It is composed of a paper base material provided with a foam layer formed by heating a thermoplastic resin layer having at least one layer of water-based ink coating on one side.
When the foam thickness in the foam layer when the water-based ink is not applied is X and the foam thickness in the water-based ink-coated portion of one layer is Y, the foam suppression rate represented by the following formula [1] is 40% or less. A raw material sheet characterized by that.

[2] The water-based ink contains a colorant and a binder resin, and contains 30% by mass or more of a urethane-based resin having a glass transition point of −20 ° C. or higher and 30 ° C. or lower in the resin solid content of the binder resin [1]. ] The raw material sheet described in.
[3] The raw material sheet according to [1] or [2], wherein the water-based ink further contains an extender pigment.
[4] The raw material sheet according to [3], wherein the extender pigment is silicon dioxide.
[5] The raw material sheet according to any one of [1] to [4], wherein the foam layer includes a foam suppression portion.
[6] The foam suppression portion is formed by heating a thermoplastic resin layer having a foam suppression ink coating portion.
The raw material sheet according to [5], wherein the foam suppression ink contains 70% by weight or more of a resin having a glass transition point of 60 ° C. or higher and 120 ° C. or lower in the resin solid content of the binder resin.
[7] The raw material sheet according to [6], wherein the resin having a glass transition point of 60 ° C. or higher and 120 ° C. or lower is an acrylic resin.
[8] A foamable paper container comprising the raw material sheet according to any one of [1] to [7].

According to the present invention, there is provided a raw material sheet containing an ink having a small impact on the environment, a foamable paper product having a smooth print layer surface and an excellent appearance, and a foamable paper container made of the raw material sheet. be able to.

It is sectional drawing which shows typically one Embodiment of the raw material sheet (before foaming) of this invention. It is sectional drawing which shows typically one Embodiment of the raw material sheet (after foaming) of this invention. It is sectional drawing which shows typically the other embodiment of the raw material sheet (before foaming) of this invention. It is sectional drawing which shows typically the other embodiment of the raw material sheet (after foaming) of this invention.

<< Raw material sheet >>
In one embodiment, the present invention is a raw material sheet used for a foamable paper product, which is a paper base material provided with a foam layer formed by heating a thermoplastic resin layer having at least one layer of water-based ink coating on one side. When the foam thickness in the foam layer when the water-based ink is not applied is X and the foam thickness in the water-based ink-coated portion of one layer is Y, the foam suppression rate represented by the following formula [1] is 40%. The following raw material sheets are provided.

According to the raw material sheet of the present embodiment, a foamable paper product having a smooth printed layer surface and an excellent appearance can be obtained. In addition, since no organic solvent other than alcohol is used, the ratio of alcohol in the solvent is 30% or less, and the rest is water, the environmental load is smaller than that of the conventional oil-based ink. Further, the water-based ink used for the raw material sheet of the present embodiment develops color in the same manner as the water-based gravure printing method even in the water-based flexographic printing method with a low coating amount, and clear printing can be obtained.

<Structure>
1A and 1B are cross-sectional views schematically showing an embodiment of the raw material sheet of the present invention. FIG. 1A shows a raw material sheet before heating and foaming, and FIG. 1B shows a raw material sheet after heating and foaming.
The raw material sheet 10 before foaming of the present embodiment has a water-based ink non-painted region A and a water-based ink coated region B arranged adjacent to each other in a plan view, and has a non-foamed thermoplastic resin layer 2a and a paper base. The material 3, the foamed thermoplastic resin layer 2b, and the printing layer 1 (the first water-based ink coating portion 1a and the second water-based ink coating portion 1b) are laminated in this order.
Further, in the foamed raw material sheet 20 of the present embodiment, the foamed layer 2b'is a foamed thermoplastic resin 2b having a printing layer 1 (a first water-based ink coating portion 1a and a second water-based ink coating portion 1b). It is composed of a normal foaming portion 4 existing in the water-based ink non-painting region A and a printing foaming portion 5 existing in the water-based ink coating region B. By coating with the water-based ink, the printed foamed portion 5 is slightly suppressed from foaming as compared with the normal foamed portion 4. Further, the print foam portion 5 includes a first print foam portion 5a formed in a region where the first water-based ink coating portion is exposed on the surface, that is, a one-layer water-based ink coating portion, and a second water-based portion. It consists of a region where the ink-coated portion is exposed on the surface, that is, a second print foam portion 5b formed in the two-layer water-based ink-coated portion.

In the foamed raw material sheet 20 of the present embodiment, when the foam thickness in the water-based ink non-painted portion (normally foamed portion 4) is X and the foam thickness in the one-layer water-based ink coated portion is Y, the following formula [ The foaming suppression rate represented by 1] is 40% or less, preferably 39% or less, and more preferably 38% or less.
When the foaming suppression rate is within the above range, the boundary between the non-coated portion of the water-based ink and the printed layer becomes a smooth printed matter, and the printed matter can be clearly seen.
Further, in the case where the water-based ink coated portion is formed by the flexographic printing method in the foamed raw material sheet 20 of the present embodiment (that is, the amount of water-based ink applied per unit area in the water-based ink coated portion is 0.1 g / m ² or more). When 6.0 g / m ² or less), the foam thickness in the water-based ink non-painted portion (normally foamed portion 4) is X, and the foam thickness in the one-layer water-based ink coated portion is Y, the following formula [ The foaming suppression rate represented by 1] is 30% or less, preferably 29% or less, and more preferably 28% or less. When the water-based ink coating part is formed by the flexographic printing method, when the water-based ink coating part is formed by the gravure printing method (that is, the amount of water-based ink applied per unit area in the water-based ink coating part is, for example, 7.0 g / m. ^{Since the} amount of ink used is smaller than that of ² or more and 15.0 g / m ² or less), the foaming suppression rate can be made smaller.

For X and Y, the average value of the measured values of the foam thickness in the water-based ink-coated portion of each layer may be used.
Further, in FIGS. 1A and 1B, a raw material sheet including a two-layer water-based ink-coated portion is illustrated, but the foam thickness in the water-based ink-coated portion having two or more layers, for example, three layers and four layers, is also shown for each layer. The foaming thickness in the water-based ink-coated portion may be measured, and the average value thereof may be used to calculate the foaming suppression rate by applying a numerical value to the above formula [1].
For example, in FIG. 1B, when the foaming thickness in the two-layer water-based ink coated portion is Y', the foaming suppression rate may be calculated by using Y'instead of Y in the above formula [1].

Further, the first water-based ink and the second water-based ink used for the printing layer may have the same color or different colors.

Further, in the foamed raw material sheet 20 of the present embodiment, when the foam thickness in the water-based ink coated portion of the first layer is Y and the foam thickness in the water-based ink coated portion of the two layers is Y', the following formula [2 ] Is 20% or less, preferably 19% or less, and more preferably 18% or less.
When the foaming suppression rate is within the above range, the surface of the print layer is smooth and the print can be clearly seen.

2A and 2B are cross-sectional views schematically showing another embodiment of the raw material sheet of the present invention. FIG. 2A shows a raw material sheet before heating and foaming, and FIG. 2B shows a raw material sheet after heating and foaming. In FIGS. 2A and 2B, the same components as those shown in the already explained figures are designated by the same reference numerals as those in the already explained figures, and detailed description thereof will be omitted.

The raw material sheet 30 before foaming shown here is the same as the raw material sheet 10 before foaming shown in FIG. 1A, except that the foaming suppression ink coating portion 1c is provided. That is, the raw material sheet 30 before foaming has a water-based ink non-coated region A and a water-based ink coated region B arranged adjacent to each other in a plan view, and has a non-foamed thermoplastic resin layer 2a and a paper base material. 3. The foam layer (foam thermoplastic resin layer) 2b and the printing layer 1 (first water-based ink coating portion 1a, second water-based ink coating portion 1b, and foam suppression ink coating portion 1c) are laminated in this order. ing.
Further, the foamed raw material sheet 40 shown here is the same as the foamed raw material sheet 20 shown in FIG. 1B, except that the foaming suppressing portion 5c is provided. That is, in the foamed raw material sheet 40, the print foam portion 5 is the first print foam formed in the region where the first water-based ink-coated portion is exposed on the surface (that is, the one-layer water-based ink-coated portion). A portion 5a, a second print foam portion 5b formed in a region where the second water-based ink coating portion is exposed on the surface (that is, a two-layer water-based ink coating portion), and a foam suppression ink coating portion 1c are on the surface. It is composed of a foaming suppressing portion 5c formed in the exposed region.

In the foamed raw material sheet 40 of the present embodiment, when the foam thickness in the water-based ink coated portion of the two layers is Y'and the foam thickness in the foam suppression ink coated portion is Z, it is represented by the following formula [3]. The foaming suppression rate is 40% or more, preferably 50% or more, more preferably 60% or more, and further preferably 65% or more.
When the foaming suppression rate is within the above range, it is possible to obtain a raw material sheet having a smooth printed surface and excellent designability due to unevenness.

For Y'and Z, the average value of the measured values of the foam thickness in the second water-based ink coating portion or the foam suppression ink coating portion may be used.
Further, in FIGS. 2A and 2B, a raw material sheet provided with a two-layer water-based ink coating portion is illustrated, but the foam thickness in the water-based ink coating portion such as two or more layers, for example, three layers and four layers, is also shown for each layer. The foaming suppression rate may be calculated by measuring the foaming thickness in the water-based ink coating portion or the foaming suppression ink coating portion provided on the water-based ink coating portion, and applying a numerical value to the above formula [3] using the average value thereof.

The raw material sheet of the present invention is not limited to the one shown in FIGS. 1A to 2B, and a part of the composition shown in FIGS. 1A to 2B is changed or deleted within a range not impairing the effect of the present invention. Or, other configurations may be added to those described above.

For example, the raw material sheets shown in FIGS. 1A to 2B may include two or more layers, for example, three layers and four layers of water-based ink coating portions. Above all, the water-based ink coating portion preferably has 2 or more layers and 8 or less layers.
Further, the raw material sheets shown in FIGS. 1A to 2B may be those in which one side is coated with water-based ink and covered with a printing layer, that is, those not provided with a water-based ink non-coated portion.
Further, the raw material sheets shown in FIGS. 1A to 2B may be provided with foamed thermoplastic resin layers on both sides.

Further, in the raw material sheets shown in FIGS. 2A and 2B, a foam suppression ink coating portion may be provided on the first water-based ink coating portion. In this case, when the foam thickness in the water-based ink-coated portion of the one layer is Y and the foam thickness in the foam-suppressing ink-coated portion is Z in the raw material sheet, the foam suppression rate represented by the following formula [4] is obtained. It is 40% or more, preferably 50% or more, more preferably 60% or more, and further preferably 65% or more.
When the foaming suppression rate is within the above range, it is possible to obtain a raw material sheet having a smooth printed surface and excellent designability due to unevenness.

Further, in the raw material sheet shown in FIGS. 2A and 2B, a foam suppression ink coating portion may be provided on the first water-based ink coating portion and the second water-based ink coating portion, respectively. The foaming suppression rate at this time may be calculated using the above equations [3] and [4], respectively.
Further, in the raw material sheets shown in FIGS. 2A and 2B, a foam-suppressing ink-coated portion may be provided on the water-based ink non-coated portion. In this case, when the foam thickness in the water-based ink unpainted portion is X and the foam thickness in the foam suppression ink coated portion is Z in the raw material sheet, the foam suppression rate represented by the following formula [5] is 40%. It is more preferably 50% or more, more preferably 60% or more, and further preferably 65% or more.

<Constituent material>
The materials constituting the raw material sheet of the present embodiment will be described below.

[Print layer]
In the raw material sheet of the present embodiment, the thickness of the water-based ink-coated portion before heating after drying is preferably 2 μm or less per layer. When it is 2 μm or less, it is possible to obtain a smooth printed surface without suppressing foaming.
When the water-based ink coating portion is, for example, two layers, the printed layer after drying is preferably 4 μm or less, and when the water-based ink coating portion is, for example, three layers, the printed layer after drying is 6 μm or less. Is preferable.
When the raw material sheet of the present embodiment is provided with a foam-suppressing ink-coated portion, the thickness of the foam-suppressing ink-coated portion before heating may be, for example, 0.1 μm or more and 2 μm or less. It may be 2 μm or more and 1 μm or less.
Foaming suppression before heating When the thickness of the ink-coated portion after drying is equal to or higher than the above lower limit, it has an excellent foaming suppressing effect. Further, since the thickness of the foam-suppressing ink-coated portion before heating is equal to or less than the above upper limit value, it is not necessary to print more than once even in gravure printing, and the amount of ink used can be suppressed. it can. Further, since it is not necessary to use two printing units, it is possible to save the time and labor required for cleaning the ink after use, and the number of colors that can be used for the water-based ink of the present embodiment, which suppresses low foaming. Can be kept a lot.

(Aqueous ink)
The water-based ink used for the printing layer of the present embodiment is obtained by adding a solvent to the structure of the water-based ink coated portion in a dry state. That is, the water-based ink contains a colorant, a binder resin, and a solvent.
In addition, the water-based ink may be an auxiliary agent (for example, a polyolefin wax such as polyethylene wax; various known waxes such as fatty acid amide, fatty acid ester, paraffin wax, polytetrafluoroethylene (PTFE) wax, and carnauba wax). , Leveling agent, defoaming agent, pigment dispersant, lubricant and other various ink additives may be contained.

◎ Colorant The colorant may be an inorganic colorant or an organic colorant.
Examples of the inorganic colorant include titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, aluminum hydroxide, talc, clay, kaolin, chromium oxide, silica, carbon black, aluminum, mica (mica) and the like. Can be mentioned.
Titanium oxide is preferable as the white colorant, and titanium oxide having a basic pigment surface is more preferable, from the viewpoints of coloring power, hiding power, chemical resistance, and weather resistance. Although aluminum is in the form of powder or paste, it is preferably used in the form of paste from the viewpoint of handleability and safety, and whether to use leafing or non-leafing is appropriately selected from the viewpoint of brightness and concentration.
Barium sulphate, calcium carbonate, aluminum hydroxide, talc, clay and kaolin are called extender pigments and are used as bulking agents to improve fluidity, strength and optical properties.
On the other hand, examples of the organic colorant include organic pigments and dyes used in general inks, paints, recording agents and the like. Examples thereof include azo, phthalocyanine, anthraquinone, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, quinophthalone, azomethine azo, dictopyrrolopyrrole, isoindoline and the like. The content of the colorant can be appropriately selected in consideration of the desired color tone of the ink and the like, but generally, it may be 50% by weight or less based on the total weight of the water-based ink, and is the upper limit value. By the following, the content of the colorant is such that the required inking concentration can be obtained.

When the water-based ink used in the present embodiment is white, the content of the white pigment may be generally 20% by weight or more and 50% by weight or less based on the total weight of the water-based ink, and is within the above range. By being present, the content of the pigment is such that the required inking concentration can be obtained. From the viewpoint of hiding property, pigment concentration, and light resistance, the white pigment is preferably titanium dioxide. When the water-based ink used in the present embodiment is colored, examples of the colored pigments contained include colored organic pigments and colored inorganic pigments such as red iron oxide, prussian blue, ultramarine, carbon black, and graphite. Be done. From the viewpoint of color development and light resistance, the colored pigment is preferably an organic pigment. Generally, the content of the colored pigment may be 10% by weight or more and 30% by weight or less based on the total weight of the water-based ink, and if it is within the above range, the required deposition concentration can be obtained. It becomes the content.

The water-based ink used in the present embodiment preferably further contains an extender pigment. As will be described later, the water-based ink used in this embodiment contains a large amount of urethane-based resin. Therefore, the water-based ink-coated part becomes sticky after foaming, but in the present embodiment, by including the extender pigment, it is possible to suppress the stickiness of the water-based ink-coated part after foaming while maintaining a large content of the urethane-based resin. it can. Further, it is possible to adjust the brightness, glossiness, and feel after processing the foamable paper product.

Examples of the extender pigment include silicon dioxide and the like. The silicon dioxide may be, for example, a compound known as "synthetic silica" produced by a known method. Typical production methods for synthetic silica are a wet method that produces ultrafine hydrated silicic acid by reacting sodium silicate made from high-purity silica sand with an acid, or silicon tetrachloride is burned and hydrolyzed in the gas phase. There is a dry method.

The silicon dioxide used in the present embodiment is not particularly limited by the synthetic method, and examples thereof include untreated silicon dioxide (untreated silica).
The particle size of silicon dioxide used in the present embodiment is preferably 2 μm or more and 20 μm or less, and more preferably 3 μm or more and 10 μm or less. By using silicon dioxide having a particle size of at least the above lower limit, it is possible to prevent the viscosity of the water-based ink from increasing and prevent the ink state from deteriorating. Further, by using silicon dioxide having a particle size equal to or less than the above upper limit value, it is possible to prevent the ink film from being inferior in foaming followability to the foaming of the low melting point resin film used as the foaming thermoplastic resin during the heat treatment during container manufacturing. be able to.

The particle size of silicon dioxide is generally measured by a Coulter counter method using a change in electrical resistance, a laser method using light scattering, or the like. In the present embodiment, it means the average particle size obtained by the measurement using the laser method.

When silicon dioxide is contained in the present embodiment, the content of silicon dioxide is preferably 0.2% by mass or more and 5% by mass or less, and 0.5% by mass or more, based on the total mass of the water-based ink. More preferably, it is 5% by mass or less. When the content of silicon dioxide is in the above range, the viscosity can be adjusted to be easy to handle as a water-based ink. Further, it is possible to adjust the feeling of brightness and the feeling of touch after processing the foamable paper product.

◎ Binder resin The binder resin contains a urethane resin having a glass transition point of −20 ° C. or higher and 30 ° C. or lower, preferably −15 ° C. or higher and 0 ° C. or lower, and the urethane resin is contained in the resin solid content of the binder resin. Is preferably contained in an amount of 30% or more, more preferably 50% or more, further preferably 70% or more, and particularly preferably 90% or more.
When the glass transition point of the urethane resin is −20 ° C. or higher, the occurrence of blocking can be suppressed, and when the temperature is 30 ° C. or lower, the suppression of foaming can be suppressed.
The term "blocking" generally means that the surface of the raw material sheet having the printing layer and the surface on the opposite side of the raw material sheet stick to each other when printing, drying, and subsequently winding the ink.
When the amount of the urethane-based resin contained in the binder resin is within the above range, foaming of the thermoplastic resin is hardly suppressed, and a raw material sheet having a smooth printed surface can be obtained.

○ Urethane-based resin As the urethane-based resin such as polyurethane resin and polyurethane urea resin, urethane-based tree-based resin for known and conventional printing ink can be selected and used. For example, a urethane resin obtained by reacting a polymer polyol with a polyisocyanate can be mentioned.

High Polymer polyols Polymer polyols that can be used in urethane resins include, for example, polyether polyols such as PEG (polyethylene glycol), PPG (polypropylene glycol) and PTMG (polyoxytetramethylene glycol); ethylene glycol, 1 , 2-Propanediol, 1,3-Propanediol, 1,3-Butandiol, 1,4-Butanediol, Neopentyl glycol, Pentadiol, Methylpentadiol, Hexadiol, Octanediol, Nonandiol, Methylnonanediol , Diethylene glycol, triethylene glycol, dipropylene glycol and other low molecular weight glycols, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimeric acid. , Dibasic acids such as azelaic acid, sebacic acid, dimer acid, or polyester polyols obtained by dehydration condensation with these anhydrides; other polycarbonate diols, polybutadiene glycols, bisphenol A with ethylene oxide or propylene oxide Various known polyols such as glycols and dimerdiols obtained by addition can be mentioned.
These polymer polyols may be used alone or in combination of two or more. Among them, the polymer polyol preferably contains polyether polyols, and more preferably PEG (polyethylene glycol), from the viewpoint of resolubility of water-based ink.

-Polyisocyanate As the polyisocyanate that can be used for urethane-based resins, for example, various known diisocyanates of aromatic, aliphatic or alicyclic group can be mentioned. More specifically, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzylisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, cyclohexane- 1,4-Diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, norbornan diisocyanate, m-tetramethylxylylene diisocyanate Examples thereof include diisocyanate, which is obtained by converting the carboxy group of isocyanate or dimer acid into an isocyanate group.

-Introduction of carboxy group To introduce a carboxy group into the resin, a polyol having a carboxy group can be used. Examples of polyols having a carboxy group include dimethylol alkanoic acids such as 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid, and 2,2-dimethylol valeric acid; glutamine, asparagine, lysine, and diaminopropionic acid. Examples thereof include diamine-type amino acids such as ornithine, diaminobenzoic acid, and diaminobenzenesulfonic acid. These may be used alone or in combination of two or more.

In the production of a polyurethane urea resin, a polymer polyol, a polyisocyanate, and a polyol containing a carboxy group are reacted to form a polyurethane resin, and then a urea bond is further introduced using a chain extender and a reaction terminator. , Can be synthesized. When the urethane-based resin used in the water-based ink of the present embodiment is a polyurethane urea resin, the coating film tends to be tougher and the physical characteristics of the coating film tend to be improved by having a urea bond.

-Chain extender As the chain extender that can be used when introducing a urea bond, various known amines can be used. Examples of the amines include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropyl. Examples thereof include ethylenediamine, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and dimerdiamine obtained by converting the carboxy group of dimer acid into an amino group. These may be used alone or in combination of two or more. Among them, the chain extender in the present embodiment is preferably amines having a hydroxyl group, and tends to have good resolubility.

-Reaction terminator Examples of the reaction terminator include dialkylamines such as di-n-dibutylamine, monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, and tri (hydroxymethyl) aminomethane. , 2-Amino-2-ethyl-1,3-propanediol, N-di-2-hydroxyethylethylenediamine, N-di-2-hydroxyethylpropylenediamine, N-di-2-hydroxypropylethylenediamine and other hydroxyl groups. Examples thereof include amines, glycine, alanine, glutamic acid, taurine, aspartic acid, aminobutyric acid, valine, aminocaproic acid, aminobenzoic acid, aminoisophthalic acid, sulfamic acid and other monoamine-type amino acids. The reaction terminator may be used alone or in combination of two or more.

-Neutralizing agent In order to solubilize urethane-based resins such as polyurethane resin and polyurethane urea resin, it is preferable to neutralize part or all of the carboxy groups in the resin with a basic compound. Examples of the basic compound include sodium hydroxide, potassium hydroxide, ammonia, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, ethanolamine, propanolamine, diethanolamine, N-methyldiethanolamine and dimethylamine. , Diethylamine, triethylamine, N, N-dimethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, morpholin and the like. These neutralizers may be used alone or in combination of two or more. Among them, the neutralizing agent in the present embodiment is preferably ammonia from the viewpoint of water resistance, residual odor and the like of the printed matter.

-Synthesis method As a method for synthesizing urethane-based resins such as polyurethane resin and polyurethane urea resin, for example, an acetone method using an organic solvent that is inert to isocyanate and hydrophilic, a solvent-free synthesis method that does not use any solvent, etc. Can be mentioned. Examples of the organic solvent inert to isocyanate and hydrophilic are ethers such as tetrahydrofuran and dioxane, esters such as ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, dimethylformamide and N-methylpyrrolidone. Such as amides and the like. Since the organic solvent is usually removed by vacuum distillation (solvent removal), and in order to accelerate the drying rate even when the solvent is not removed, it is preferable to use a solvent having a boiling point lower than that of water. In the case of removing the solvent, for example, water and a basic compound may be added to the reaction solution.

○ Acrylic resin The binder resin may further contain an acrylic resin.
As the acrylic resin, one obtained by radical copolymerization of an acrylic monomer and another monomer copolymerizable with the acrylic monomer can be used.

-Acrylic monomer The acrylic monomer is not particularly limited, and indicates that it is, for example, methyl (meth) acrylate (note that it is either methyl acrylate or methyl methacrylate. The same applies hereinafter. ), Ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate and other alkyl group-containing (meth) acrylic single amounts. Body; hydroxyl group-containing (meth) acrylic monomer such as 2-hydroxyethyl (meth) acrylate; ethylenically unsaturated carboxylic acid such as (meth) acrylic acid; dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) ) Amino group-containing (meth) acrylic monomer such as acrylate; amide-containing (meth) acrylic monomer such as (meth) acrylamide and ethyl (meth) acrylamide; nitrile group-containing (meth) acrylic monomer such as acrylonitrile Monomer; Examples thereof include an epoxy group-containing (meth) acrylic monomer such as glycidyl (meth) acrylate.

-Other monomers copolymerizable with the acrylic monomer Other monomers copolymerizable with the acrylic monomer include, for example, aromatics such as styrene, methylstyrene, chlorostyrene, and vinyltoluene. Group hydrocarbon vinyl monomer; α, β-ethylene unsaturated carboxylic acid such as maleic acid, itaconic acid, crotonic acid, fumaric acid, citraconic acid; sulfonic acid-containing vinyl monomer such as styrene sulfonic acid and vinyl sulfonic acid. Quantities; Acid anhydrides such as maleic anhydride and itaconic anhydride; Chlorine-containing monomers such as vinyl chloride, vinylidene chloride and chloroprene; Hydroxyl-containing alkyl vinyl ethers such as hydroxyethyl vinyl ether and hydroxypropyl vinyl ether; Ethylene glycol monoallyl Ether, propylene glycol monoallyl ether, alkylene glycol monoallyl ether such as diethylene glycol monoallyl ether; α-olefin such as ethylene, propylene, isobutylene; vinyl ester such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate; methyl Vinyl ethers such as vinyl ethers, ethyl vinyl ethers, butyl vinyl ethers and cyclohexyl vinyl ethers; allyl ethers such as ethyl allyl ethers and butyl allyl ethers can be exemplified.

-Synthesis method These acrylic resin emulsions are obtained, for example, by an emulsion polymerization method. The method of emulsion polymerization is not particularly limited, and the various monomers, chain transfer agents, surfactants, radical polymerization initiators, and other additions used as necessary in an aqueous medium are conventionally known methods. An emulsion can be produced by polymerizing a monomer in a dispersion system containing an agent component as a basic composition component.

○ Other resin The binder resin may further contain a polyamide resin or a polyester resin.

-Polyamide resin The polyamide resin has an amide bond in the main chain and can be obtained, for example, by a dehydration condensation reaction using a dicarboxylic acid and a diamine.
Examples of the dicarboxylic acid include dimers obtained by dimerizing unsaturated fatty acids having 18 carbon atoms such as adipic acid, azelaic acid, sebacic acid, pimelic acid, suberic acid, nonandicarboxylic acid, fumaric acid, oleic acid and linoleic acid. Examples include acid.
These dicarboxylic acids may be used alone or in combination of two or more.
Examples of the diamine include ethylenediamine, hexamethylenediamine, tetramethylenediamine, pentamethylenediamine, m-xylenediamine, phenylenediamine, diethylenetriamine, piperazine and the like.
These diamines may be used alone or in combination of two or more.

-Polyester resin The polyester resin is, for example, (1) a method of polycondensing a predetermined acid and an alcohol, (2) a method of polycondensing a predetermined acid and an alcohol and then depolymerizing with a polybasic acid, or (3) It can be produced by a known method such as a method of polycondensing a predetermined acid and an alcohol and then adding an acid anhydride.

As the acid constituting the polyester resin, at least a polybasic acid may be used, and if necessary, a monocarboxylic acid may be mixed and used.
Examples of the polybasic acid include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids.
Specific examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, biphenyldicarboxylic acid and the like.
Specific examples of aliphatic dicarboxylic acids include citraconic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, and hydrogenated dimeric acid. Examples thereof include saturated aliphatic dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, and unsaturated aliphatic dicarboxylic acids such as dimeric acid.
Specific examples of the alicyclic dicarboxylic acid include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, and 2,5-norbornene anhydride. Examples thereof include dicarboxylic acid, tetrahydrophthalic acid and tetrahydrophthalic anhydride.
Further, as the polybasic acid, a small amount of 5-sodium sulfoisophthalic acid or 5-hydroxyisophthalic acid may be used as needed.
Trifunctional or higher functional polybasic acids can also be used, for example, trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic acid anhydride, trimesic acid, ethylene. Glycolbis (anhydrotrimellitic acid), glycerol tris (anhydrotrimellitic acid), 1,2,3,4-butanetetracarboxylic acid and the like can be mentioned.

Specific examples of the monocarboxylic acid include fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexanoic acid, and 4 -Hydroxyphenyl stearic acid and the like.

As the alcohol constituting the polyester resin, at least a polyhydric alcohol may be used, and if necessary, a monoalcohol may be mixed and used.

Examples of the polyhydric alcohol include aliphatic glycols, alicyclic glycols, and ether bond-containing glycols.
Specific examples of the aliphatic glycol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, and 1,5-. Examples thereof include pentandiol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, and 2-ethyl-2-butylpropanediol.
Specific examples of the alicyclic glycol include 1,4-cyclohexanedimethanol and the like.
Specific examples of the ether bond-containing glycol include, for example, diethylene glycol, triethylene glycol, dipropylene glycol; an ethylene oxide adduct of bisphenols (bisphenol A) such as 2,2-bis [4- (hydroxyethoxy) phenyl] propane; Ethylene oxide adducts of bisphenols (bisphenol S) such as bis [4- (hydroxyethoxy) phenyl] sulfone; polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like can be mentioned.
A trifunctional or higher functional polyhydric alcohol can also be used, and examples thereof include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

Specific examples of the monoalcohol include stearyl alcohol, 2-phenoxyethanol and the like.

In order to make the polyester resin water-soluble, it is preferable to neutralize a part or all of the carboxy groups in the resin with a basic compound. Examples of the basic compound include those similar to those exemplified in the above-mentioned “neutralizing agent”.

In the present embodiment, the binder resin preferably contains a total of 70% or less of a resin other than the urethane-based resin, more preferably 50% or less, further preferably 30% or less, and 10%. It is particularly preferable to contain the following.
Since the amount of the resin other than the urethane resin contained in the binder resin is within the above range, the urethane resin is sufficiently contained, so that the foaming of the thermoplastic resin is not suppressed and the raw material sheet on the smooth printed surface is used. Can be obtained.

In the present embodiment, the content of the binder resin is preferably 15% by mass or more and 25% by weight or less based on the total mass of the water-based ink. When the content of the binder resin is at least the above lower limit value, an appropriate ink viscosity can be obtained, and when it is at least the above upper limit value, it is possible to prevent the ink fluidity from being lowered, and during ink production and printing. Work efficiency can be improved.

◎ Solvent In the present embodiment, the solvent may be any well-known compound that can be usually used as a solvent for water-based inks. For example, water; alcoholic solvents such as methanol, ethanol, isopropanol, n-propanol, n-butanol and the like can be mentioned and not limited thereto. These solvents may be contained alone or a mixture of two or more kinds may be contained.

(Foam suppression ink)
The foam suppression ink used for the printing layer of the present embodiment is obtained by adding a solvent to the structure of the foam suppression ink coating portion in a dry state. That is, the foam suppression ink contains a binder resin and a solvent.
Further, if necessary, the foaming inhibitory ink may contain various ink additives such as an auxiliary agent, a pigment dispersant, a leveling agent, a surfactant, and a defoaming agent.
Further, the foam suppression ink may contain a colorant or may not contain a colorant. In order to make it easier to see the unevenness in appearance, it is preferable that the colors of the foamed portion and the foaming suppressing portion are not significantly different. For that purpose, the foaming suppressing ink does not contain a colorant, or the colorant is added to 30 in the ink solid content. It is preferably contained in an amount of 10% by weight or less, more preferably 20% by weight or less, and further preferably 10% by weight or less.
Therefore, the foam suppression ink coating portion 1c may be colored or colorless. In the case of colorless or light color, it is preferable because the unevenness between the foamed portion 4, the first printed foamed portion 5a, the second printed foamed portion 5b, and the foam suppressing ink coating portion 1c becomes easy to see. Further, even if it is colored, when it is a cool blue or green, it is preferable because the unevenness is deeply emphasized and it becomes easy to see.

Examples of the colorant, auxiliary agent, and solvent include those similar to those exemplified in the above-mentioned (water-based ink).

The binder resin contains a resin having a glass transition point of 60 ° C. or higher and 120 ° C. or lower, and preferably contains the resin in an amount of 70% by mass or more, preferably 80% by mass or more, in the resin solid content of the binder resin. Is more preferable, and 90% by mass or more is further preferable. A high foaming suppressing effect can be obtained by containing 70% by mass or more of the resin having the glass transition point within the above range.
That is, the content of the resin, the colorant, and the auxiliary agent having the glass transition point of less than 30 ° C. or higher than 120 ° C. in the foam suppression ink coating portion 1c is preferably less than 30% by mass, preferably 20% by mass. It is more preferably less than, and even more preferably less than 10% by mass.

Further, the glass transition point of the resin is preferably 60 ° C. or higher and 120 ° C. or lower.
By using a foam-suppressing ink containing a glass transition point within the above range, foaming can be sufficiently suppressed by one printing even in a water-based flexographic printing method in which the amount of ink applied is small, and unevenness can be prevented. By controlling, excellent design can be imparted to the printed surface.
Examples of the resin having a glass transition point of 60 ° C. or higher and 120 ° C. or lower include, but are not limited to, acrylic resins and polyester resins.

The acrylic resin has a glass transition point of 60 ° C. from among the acrylic monomer exemplified in the above-mentioned "○ Acrylic resin" and other monomers copolymerizable with the acrylic monomer. It may be synthesized by appropriately selecting and polymerizing so that the temperature is 120 ° C. or lower.
Further, as the polyester resin, various acids and various alcohols exemplified in the above-mentioned ". Polyester resin" are used, for example, various acids and various alcohols are polycondensed, and then depolymerized with various polybasic acids. In the synthesis method, the type of acid and alcohol may be appropriately selected so that the glass transition point is 60 ° C. or higher and 120 ° C. or lower, and the depolymerization ratio may be controlled for synthesis.

Among them, the resin having the glass transition point of 60 ° C. or higher and 120 ° C. or lower is preferably an acrylic resin.

[Foam thermoplastic resin layer]
In the raw material sheet of the present embodiment, the foamed layer is formed by heating a thermoplastic resin layer. That is, the foamed layer is a foamed thermoplastic resin layer (foamed thermoplastic resin layer). The thermoplastic resin used for the foamed thermoplastic resin layer is not particularly limited as long as it can be extruded and laminated and can be foamed, and either a crystalline resin or a non-crystalline resin can be used. .. Examples of the crystalline resin include polyolefin resins such as polyethylene, polypropylene and polymethylpentene; polyester resins, polyamides, polyacetals, PPS resins and the like. Examples of the non-crystalline resin include polystyrene, polyvinyl chloride, ABS resin, acrylic resin, modified PPE, polycarbonate, polyurethane, polyvinyl acetate, and non-crystalline polyethylene terephthalate (PET). The melting point of these thermoplastic resins is preferably about 80 to 120 ° C. Further, these thermoplastic resins may use a single resin in a single layer or a plurality of resins in a plurality of layers, but are preferably a single layer from the viewpoint of foamability.

Among them, polyethylene is preferable as the thermoplastic resin used for the foamed thermoplastic resin layer because it is excellent in laminating suitability and foamability. Polyethylene is broadly classified into linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene.
As for the density, linear low density polyethylene is 888 to 910 kg / m ³ , low density polyethylene is 910 kg / m ³ or more and 925 kg / m ³ or less, medium density polyethylene is 925 kg / m ³ or more and 940 kg / m ³ or less, and even higher. The density polyethylene is 940 kg / m ³ or more and 970 kg / m ³ or less.
The melting point of linear low-density polyethylene is 55 ° C or higher and 120 ° C or lower, low-density polyethylene is 105 ° C or higher and 120 ° C or lower, medium-density polyethylene is 120 ° C or higher and 125 ° C or lower, and high-density polyethylene is 125 ° C or higher and 135 ° C or lower. It is as follows.

The thickness of the foamed layer (foamed thermoplastic resin layer) is not particularly limited as long as it is sufficient to impart at least one of the desired heat insulating properties and design properties, and is not particularly limited. , The first print foaming portion and the second print foaming portion may be 0.01 mm or more and 4 mm or less, and the foam suppression portion may be 0 mm or more and 1 mm or less.

[Non-foamed thermoplastic resin layer]
In the raw material sheet of the present embodiment, in order to improve the foaming efficiency, the opposite wall surface side of the wall surface having the foamed thermoplastic resin layer of the body member is made of a thermoplastic resin having a melting point higher than that of the foamed thermoplastic resin layer and is heat-treated. It is preferable to cover it with a thermoplastic resin layer (non-foamed thermoplastic resin layer) that does not foam when it is formed, or an aluminum foil or the like. If one side of the paper base material is left as it is (the state where it is not coated with the laminate or coating layer), the moisture in the paper will evaporate from this uncoated surface into the atmosphere during the heat treatment, which is sufficiently reliable. It becomes difficult to foam. Therefore, by providing such a coating layer, the moisture in the paper can be efficiently contributed to foaming. When the raw material sheet is used as a foamable paper container, if these non-foamed thermoplastic resin layers, aluminum foil, etc. are present on the inner wall surface side of the body member, the filling liquid or the like permeates into the paper. Can be prevented, which is preferable.

The thermoplastic resin used for the non-foamed thermoplastic resin layer of the raw material sheet of the present embodiment may be the same as or different from the foamed thermoplastic resin layer. In the case of the same, the difference in melting point can be caused by making the difference in density. For example, when polyethylene is selected as both thermoplastic resins, the foamed thermoplastic resin layer is low-density polyethylene, and the non-foamed thermoplastic resin layer is medium-density or high-density polyethylene. The difference in melting point between the foamed thermoplastic resin layer and the non-foamed thermoplastic resin layer in the thermoplastic resin is preferably 5 ° C. or more, and the melting point of the thermoplastic resin in the non-foamed thermoplastic resin layer is melted during heating. It is not particularly limited as long as it can prevent the diffusion of evaporated water, but it is preferably 125 ° C. or higher.

[Paper base material]
As the paper base material used for the raw material sheet of the present embodiment, for example, chemical pulp and mechanical pulp obtained from wood are mainly used, and non-wood pulp such as kenaf and bamboo is blended therein as needed. Examples thereof include, and are not limited to, a paper substrate obtained by making a paper by the paper making process of. Above all, the paper base material used for the raw material sheet of the present embodiment preferably contains chemical pulp. Since it contains chemical pulp, it is easier to increase the density than when mechanical pulp is used, and it suppresses yellowing when exposed to light for a long time or stored at high temperature for a long time. In addition, the strength and rigidity when it is assumed to be used for a container are increased.
The blending ratio of the chemical pulp with respect to the total raw material pulp used for the paper base material is preferably 80% by weight or more, more preferably 90% by weight or more, still more preferably 95% by weight or more.
Further, it is preferable that the chemical pulp contains a large amount of fibers derived from coniferous trees because it has high foamability.
The blending ratio of the softwood-derived chemical pulp with respect to the total raw material pulp used for the paper base material is preferably 5% or more, more preferably 10% or more, still more preferably 20% or more.

The base paper basis weight of the paper base material may be, for example, 25 g / m ² or more and 500 g / m ² or less. When the raw material sheet of the present embodiment is used for a container, the base paper basis weight of the paper base material may be, for example, 30 g / m ² or more and 400 g / m ² or less in consideration of foamability.
When the base paper basis weight of the raw material sheet of the present embodiment is at least the above lower limit value, it is possible to sufficiently secure the amount of water required for imparting heat insulation and design by foaming. Further, when the base paper basis weight of the raw material sheet of the present embodiment is not more than the above upper limit value, it is easy to process after foaming, and the cost of the paper base material can be suppressed within an appropriate range.

The drainage degree (“Canadian Standard” freeness; CSF) of the pulp used for the paper substrate is preferably 150 mL or more and 600 mL or less, and more preferably 200 mL or more and 580 mL or less. When the CSF of the pulp is 600 mL or less, it is difficult for water vapor to permeate inside the paper base material, and it is difficult for water vapor to escape from the end face of the paper base material, so that the foam thickness becomes large. When the CSF of the pulp is 200 mL or more, the power consumption for beating the pulp to reduce the degree of drainage is not increased, which is excellent in terms of cost. In addition, it is possible to relax the equipment for enhancing the pulp beating capacity.

The density of the paper substrate is preferably 0.6 g / cm ³ or more, more preferably 0.7 g / cm ³ or more, and even more preferably 0.8 g / cm ³ or more.
The thickness of the paper base material may be, for example, 20 μm or more and 500 μm or less.

Generally, as a method for producing a paper base material, the above-mentioned pulp, water, and a paper material prepared by adding a filler or other chemicals as necessary are sprayed onto the wire of a paper machine, and a wire part is used. After dehydration with, water squeezing with the press part, drying with the dryer part, and if necessary, a size press that gives strength and water resistance to the paper, and a calendar process that smoothes the unevenness of the paper surface are applied to make the paper and finish it. The paper is wound up and finished to the specified winding size. Further, in order to impart paper strength and water resistance to the paper, chemicals such as polyvinyl alcohol (PVA), starch, and surface sizing agent may be used alone or in combination of two or more as appropriate. The production of the paper base material in the present embodiment is not limited to this.

<Manufacturing method of raw material sheet>
In one embodiment, the present invention is a method for producing a raw material sheet used for a foamable paper product, which comprises a thermoplastic resin layer forming step of forming a thermoplastic resin layer on at least one surface of a paper base material, and the thermoplastic resin. A water-based ink coating portion forming step of applying the above-mentioned water-based ink to the surface of the paper substrate after the layer forming step on which the thermoplastic resin layer is formed and drying the paper base material to form the water-based ink coating portion. Provided is a manufacturing method including a foaming step of foaming the thermoplastic resin layer to form a foamed layer composed of a normal foamed portion and a printed foamed portion after the water-based ink coating portion forming step.

According to the manufacturing method of the present embodiment, it is possible to obtain a raw material sheet having a smooth printed surface and excellent heat insulating properties.
Hereinafter, each step will be described in detail.

[Thermoplastic resin layer forming process]
First, a thermoplastic resin layer is formed on at least one side of the paper base material.
The method for forming the thermoplastic resin layer is not particularly limited, and for example, if the thermoplastic resin layer is laminated by appropriately using a method such as an extrusion laminating method, a wet laminating method, a dry laminating method, or the like, which is bonded to a pre-filmed material. Good. Above all, as a method for forming the thermoplastic resin layer, the extrusion laminating method is preferable from the viewpoint of adhesion to the paper substrate, foamability and the like. In the extruded laminate, for example, a thermoplastic resin layer is extruded from a T-die in the form of a molten resin film on a surface coated with a foaming accelerator of a paper base material, and cooled between a cooling roll and a nip roll facing the same. It is a method of crimping while crimping. In extruded laminating, operating conditions such as resin melting temperature and laminating speed may be appropriately set depending on the type of resin used and the apparatus, and are not particularly limited. Generally, for example, the melting temperature is 200 ° C. or higher and 350 ° C. or lower and the laminating speed. Is 50 m / min or more and 200 m / min or less. Further, it is preferable to use a nip roll having a hardness of 70 degrees or more (JIS K-6253) and perform pressing and crimping at a linear pressure of 15 kgf / cm or more.

If necessary, corona treatment, ozone treatment, or the like may be performed in order to improve the adhesiveness of the paper base material or the thermoplastic resin.

The thickness of the thermoplastic resin layer (foamed thermoplastic resin layer before heating) is sufficient to impart desired heat insulating properties when the foamed layer (foamed thermoplastic resin layer) is formed after heating. If it is good, it is not particularly limited, but for example, it may be 20 μm or more and 90 μm or less.

The thickness of the non-foamed thermoplastic resin layer before heating may be a thickness sufficient to prevent the evaporation of evaporated water, for example, 20 μm or more and 50 μm or less.

[Aqueous ink coating part forming process]
Next, the water-based ink is applied onto the formed thermoplastic resin layer to form the water-based ink coated portion.
As the water-based ink, the same ink as those exemplified in the above-mentioned (water-based ink) may be used.
The method of applying the water-based ink on the thermoplastic resin layer is not particularly limited, and examples thereof include a water-based gravure printing method, a water-based flexographic printing method, and a screen printing method. Among them, as a method of applying the water-based ink to the paper base material, a water-based flexographic printing method, which can be applied with a low coating amount, is preferable. The water-based ink used in the present embodiment develops color in the same manner as the water-based gravure printing method even in the water-based flexographic printing method with a low coating amount, and clear printing can be obtained.

[Foaming process]
Next, the thermoplastic resin layer is heat-treated to foam the thermoplastic resin layer to form a foamed layer usually composed of a foamed portion and a printed foamed portion.

The heating temperature and heating time vary depending on the type of paper substrate and thermoplastic resin used, and the optimum combination of heating temperature and heating time for the thermoplastic resin to be used can be appropriately determined. A temperature slightly higher than the melting point of the foaming thermoplastic resin (melting point + 5 ° C or higher and 30 ° C or lower) is suitable, and generally, the heating temperature is 110 ° C or higher and 200 ° C or lower, and the heating time is 1 minute or longer and 6 minutes or lower. is there. The heating means is not particularly limited, and any means such as hot air, electric heating, and an electron beam can be used. Mass production can be carried out at low cost by heating with hot air, electric heat, or the like in a tunnel provided with a means for transporting by a conveyor.

[Formation process of foam suppression ink coating part]
In the manufacturing method of the present embodiment, the foaming suppression ink coating portion forming step may be provided after the water-based ink coating portion forming step and before the foaming step.
After the solvent of the water-based ink is dried and the water-based ink coating portion is formed, the foam suppression ink is applied to form the foam suppression ink coating portion.
As the foam suppression ink, the same ink as those exemplified in the above-mentioned (foam suppression ink) may be used.
The method of applying the foam suppression ink on the thermoplastic resin layer is not particularly limited, and examples thereof include a water-based gravure printing method, a water-based flexographic printing method, and a screen printing method. Among them, as a method of applying the foam suppression ink to the paper substrate, a water-based flexographic printing method, which can be applied with a low coating amount, is preferable.

As exemplified in <Use> described later, the obtained raw material sheet may be further processed by a known method so as to have a desired form according to the use.

<Use>
The raw material sheet of the present embodiment is used for a paper product having heat insulating properties and a smooth printed surface, and specifically, for example, a foamable paper cup, a foamable paper container, a pamphlet, and a fancy paper. , Wrapping paper, wallpaper, etc.

[Foam paper container]
In one embodiment, the present invention provides a foamable paper container made of the above-mentioned raw material sheet.

The foamable paper container of the present embodiment has a smooth printed surface, heat is not easily transferred to the hand, and has excellent heat insulating properties in practical use.

The foamable paper container of the present embodiment can be manufactured by, for example, the following method.
First, the raw material sheet is unwound from the take-up roll. Next, the blank for the body member and the blank for the bottom plate member are punched out from the raw material sheet and assembled in the shape of a container with a regular cup molding machine. Here, the foamed thermoplastic resin layer may be present on either one or both of the outer wall surface side and the inner wall surface side of the body member, and the heat insulating property, the touch, the appearance aesthetics, and the like may be appropriately determined as desired. However, if the inside of the container is a foamed surface, the foamed resin may be damaged by chopsticks, forks, etc. and enter the mouth when eating or drinking, so it is preferable that the foamed resin exists on the outer wall surface side. Therefore, for example, the body member is assembled so that the foamed thermoplastic resin layer faces the outside of the container and the non-foamed thermoplastic resin layer faces the inside of the container. As the bottom plate member, a paper substrate having a non-foamed thermoplastic resin layer provided on at least one surface on the inner surface side of the container is preferably used. This is to prevent the permeation of liquids and the like into the paper. The thermoplastic resin used for the bottom plate member may be the same as or different from the body member, and the laminating method may be the extruded laminating method, a wet laminating method, a dry laminating method, or the like, which is previously made into a film. A suitable method can be used as appropriate.

For cup noodles and the like that are left to stand for a while after injecting hot water, it is effective to provide a foamed thermoplastic resin layer on the bottom member in order to prevent heat dissipation from the bottom surface of the container. In particular, it is preferable for outdoor use and in winter and cold regions. Further, as the lid material, a material having a foamed thermoplastic resin layer may be used as well.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Example 1]
Low-density polyethylene (brand name: LC701, manufactured by Japan Polyethylene Corporation) on one side of a paper substrate of 300 g / m ² (thickness 330 μm, density 0.91 g / cm ³ , chemical pulp 100%, water content 7.8%) A density of 0.918 g / cm ³ and a melting point of 106 ° C.) was extruded and laminated to a thickness of 70 μm. Medium density polyethylene (brand name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) manufactured by Tosoh Corporation was extruded and laminated on the opposite surface of the paper substrate to a thickness of 40 μm. On the surface of this low-density polyethylene laminated film, water-based ink A (the content of solid components is 60% by mass of urethane resin (glass transition point 10 ° C.), 40% by mass of colorant. Solvent (ethanol: water = 10:90) The total content of the resin and the colorant in the dispersed state is 40% by mass.) Using the flexo proof 100 (manufactured by Matsuo Sangyo Co., Ltd.) according to each printing pattern shown in Table 1. I printed it. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. Table 1 shows the foam thickness in each ink-coated portion. Tables 3 and 5 also summarize the foaming suppression rates in each ink-coated portion.

[Example 2]
Low-density polyethylene Low-density polyethylene (brand name manufactured by Japan Polyethylene Corporation) on one side of a paper substrate of 300 g / m ² (thickness 330 μm, density 0.91 g / cm ³ , chemical pulp 100%, water content 7.8%) : LC701, density 0.918 g / cm ³ , melting point 106 ° C.) was extruded and laminated to a thickness of 70 μm. Medium density polyethylene (brand name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) manufactured by Tosoh Corporation was extruded and laminated on the opposite surface of the paper substrate to a thickness of 40 μm. On the surface of this low-density polyethylene laminated film, water-based ink B (the content of solid components is urethane resin (glass transition point 10 ° C.) 60% by mass, colorant 40% by mass. Solvent (ethanol: water = 20:80) The total content of the resin and the colorant in the dispersed state is 40% by mass.) Using each color, a printing tester (Gravure Autopurfer, manufactured by Matsuo Sangyo Co., Ltd.) according to each printing pattern shown in Table 1. Gravure printing was performed using. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. Table 1 shows the foam thickness in each ink-coated portion. Tables 3 and 5 also summarize the foaming suppression rates in each ink-coated portion.

[Example 3]
Low density polyethylene Low density polyethylene (brand name manufactured by Japan Polyethylene Corporation) on one side of a paper substrate of 260 g / m ² (thickness 280 μm, density 0.93 g / cm ³ , chemical pulp 100%, water content 7.6%) : LC701, density 0.918 g / cm ³ , melting point 106 ° C.) was extruded and laminated to a thickness of 70 μm. Medium density polyethylene (brand name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) manufactured by Tosoh Corporation was extruded and laminated on the opposite surface of the paper substrate to a thickness of 40 μm. On the surface of this low-density polyethylene laminated film, water-based ink A (the content of solid components is 60% by mass of urethane resin (glass transition point 10 ° C.), 40% by mass of colorant. Solvent (ethanol: water = 10:90) The total content of the resin and the colorant in the dispersed state is 40% by mass.), And the foam-suppressing ink F (acrylic resin (glass transition point 90 ° C.) 20% by mass, solvent (ethanol: water). = 10: 90) 80% by mass), and flexo printing was performed using a printing machine according to each printing pattern shown in Table 1. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. Table 1 shows the foam thickness in each ink-coated portion. Tables 3 and 6 summarize the foaming suppression rates in each ink-coated portion.

[Example 4]
Low density polyethylene (brand name: LC701, manufactured by Japan Polyethylene Corporation) on one side of a paper substrate of 135 g / m ² (thickness 201 μm, density 0.67 g / cm ³ , chemical pulp 100%, water content 7.0%) A density of 0.918 g / cm ³ and a melting point of 106 ° C.) was extruded and laminated to a thickness of 15 μm. Medium density polyethylene (brand name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) manufactured by Tosoh Corporation was extruded and laminated on the opposite surface of the paper substrate to a thickness of 45 μm. On the surface of this low-density polyethylene laminated film, water-based ink A (the content of solid components is 60% by mass of urethane resin (glass transition point 10 ° C.), 40% by mass of colorant. Solvent (ethanol: water = 10:90) The total content of the resin and the colorant in the dispersed state is 40% by mass.), And the foam-suppressing ink F (acrylic resin (glass transition point 90 ° C.) 20% by mass, solvent (ethanol: water). = 10: 90) 80% by mass), and flexo printing was performed using a printing machine according to each printing pattern shown in Table 1. After printing, it was placed in an oven and heated at 130 ° C. for 180 seconds. Table 1 shows the foam thickness in each ink-coated portion. Tables 3 and 6 summarize the foaming suppression rates in each ink-coated portion.

[Comparative Example 1]
Low-density polyethylene (brand name: LC701, manufactured by Japan Polyethylene Corporation) on one side of a paper substrate of 300 g / m ² (thickness 330 μm, density 0.91 g / cm ³ , chemical pulp 100%, water content 7.8%) A density of 0.918 g / cm ³ and a melting point of 106 ° C.) was extruded and laminated to a thickness of 70 μm. Medium density polyethylene (brand name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) manufactured by Tosoh Corporation was extruded and laminated on the opposite surface of the paper substrate to a thickness of 40 μm. Aqueous ink C (the content of solid components is 60% by mass of acrylic resin and 40% by mass of colorant. Resin dispersed in a solvent (ethanol: water = 5: 95)) on the surface of this low-density polyethylene laminated film. , And the total content of the colorant is 40% by mass.), And 20% by mass of the foam-suppressing ink G (acrylic resin (glass transition point 45 ° C.), solvent (ethanol: water = 10: 90) 80% by mass. %), And flexo printing was performed using Flexo Proof 100 (manufactured by Matsuo Sangyo Co., Ltd.) according to each printing pattern shown in Table 2. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. Table 2 shows the foam thickness in each ink-coated portion. In addition, the foaming suppression rates in each ink-coated portion are summarized in Tables 4, 5, and 6.

[Comparative Example 2]
Low-density polyethylene (brand name: LC701, manufactured by Japan Polyethylene Corporation) on one side of a paper substrate of 300 g / m ² (thickness 330 μm, density 0.91 g / cm ³ , chemical pulp 100%, water content 7.8%) A density of 0.918 g / cm ³ and a melting point of 106 ° C.) was extruded and laminated to a thickness of 70 μm. Medium density polyethylene (brand name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) manufactured by Tosoh Corporation was extruded and laminated on the opposite surface of the paper substrate to a thickness of 40 μm. Oil-based ink D (the content of solid components is 30% by mass of urethane resin, 20% by mass of nitrocellulose, 50% by mass of colorant. The resin content in the ink state is 10% by mass) on the surface of this low-density polyethylene laminated film. %. Total of resin, nitrocellulose, and colorant dispersed in a solvent (mixed solvent consisting of isopropyl alcohol (10%) / ethyl acetate (40%) / toluene (30%) / methyl ethyl ketone (20%)). The content was 20% by mass.), And gravure printing was performed using a printing tester (gravure autopurfer, manufactured by Matsuo Sangyo Co., Ltd.) according to each printing pattern shown in Table 2. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. Table 2 shows the foam thickness in each ink-coated portion. In addition, Table 4 summarizes the foaming suppression rate in each ink-coated portion.

From Table 3, in Example 1, Example 2, Example 3, and Example 4, the foaming suppression rate (1) was 19.0%, 38.3%, 21.1%, and 26.3%, respectively. Yes, it was 40% or less, whereas in Comparative Examples 1 and 2, it was 43.8% and 49.9%, which were higher than 40%.
Further, from Table 3, in Example 1, Example 2, and Example 3, the foaming suppression rates (2) were 26.0%, 46.7%, and 34.9%, respectively, which were 50% or less. On the other hand, from Table 4, in Comparative Examples 1 and 2, it was 61.1% and 62.0%, which were higher than 50%.

Further, from Table 5, in Examples 1 and 3 in which water-based flexographic printing was performed, the foaming suppression rates (3) were 10.3% and 17.5%, respectively, which were 20% or less. In Comparative Example 1 in which water-based flexographic printing was also performed, the ratio was 36.8%, which was higher than 20%.

Further, from Table 6, in Examples 3 and 4 to which the foam suppression ink F was applied, the foam suppression rates were 45.9%, 44.8%, and 52.9%, which were 40% or more. On the other hand, in Comparative Example 1 to which the foam suppression ink G was applied, it was 36.9% and 30.3%, which were lower than 40%.
From this, it was clarified that a sufficient foaming suppressing effect can be obtained by using the foaming suppressing ink F even in flexographic printing with a low coating amount.

From the above, by using a water-based ink containing a urethane-based resin, the foam suppression rate calculated from the foam thickness in the one-layer water-based ink coated portion with respect to the foam thickness in the foam layer when the water-based ink is not applied is 40%. It can be suppressed to the following, and the foam suppression rate calculated from the foam thickness in the two-layer water-based ink-coated part with respect to the foam thickness in the one-layer water-based ink-coated part can be suppressed to 20% or less, and the low-density polyethylene can be suppressed. It was confirmed that a foamable paper product having a smooth surface of the film could be obtained.
Further, even in flexographic printing with a low coating amount, by using a foam suppression ink containing a resin having a glass transition point of 60 ° C. or higher and 120 ° C. or lower, unevenness is formed on the printed surface of the low-density polyethylene film. It was confirmed that a foamable paper product with excellent design properties could be obtained.

According to the present invention, there is provided a raw material sheet containing an ink having a small impact on the environment, a foamable paper product having a smooth print layer surface and an excellent appearance, and a foamable paper container made of the raw material sheet. be able to.

A ... water-based ink non-painted region, B ... water-based ink coated region, X ... foam thickness in water-based ink non-painted portion (usually foamed portion 4), Y ... foam thickness in one layer of water-based ink coated portion, Y'... two layers Foam thickness in the water-based ink coating part, Z ... Foam thickness in the foam suppression ink coating part, 1 ... Printing layer, 1a ... First water-based ink coating part, 1b ... Second water-based ink coating part, 1c ... Foam suppression ink Painted part, 2a ... Non-foamed thermoplastic resin layer, 2b ... Foamed thermoplastic resin layer, 2b'... Foamed layer (foamed thermoplastic resin layer after heating), 3 ... Paper substrate, 4 ... Normal foamed part, 5 ... Printed foamed portion, 5a ... First printed foamed portion, 5b ... Second printed foamed portion, 5c ... Foaming suppressing portion, 10,30 ... Raw material sheet before foaming, 20, 40 ... Raw material sheet after foaming.

Claims (7)

A raw material sheet used for foamable paper products.
It is composed of a paper base material provided with a foam layer formed by heating a thermoplastic resin layer having at least one layer of water-based ink coating on one side.
When the foam thickness in the foam layer when the water-based ink is not applied is X and the foam thickness in the water-based ink-coated portion of one layer is Y, the foam suppression rate represented by the following formula [1] is 40% or less . ,
The water-based ink contains a colorant and a binder resin, and contains 70% by mass or more of a urethane-based resin having a glass transition point of −20 ° C. or higher and 30 ° C. or lower in the resin solid content of the binder resin. Raw material sheet.

The raw material sheet according to claim 1, wherein the water-based ink further contains an extender pigment. The raw material sheet according to claim 2 , wherein the extender pigment is silicon dioxide. The raw material sheet according to any one of claims 1 to 3 , wherein the foamed layer includes a foaming suppressing portion. The foam suppression portion is formed by heating a thermoplastic resin layer having a foam suppression ink coating portion.
The raw material sheet according to claim 4 , wherein the foam suppression ink contains 70% by weight or more of a resin having a glass transition point of 90 ° C. or higher and 120 ° C. or lower in the resin solid content of the binder resin. The raw material sheet according to claim 5 , wherein the resin having a glass transition point of 90 ° C. or higher and 120 ° C. or lower is an acrylic resin. A foamable paper container comprising the raw material sheet according to any one of claims 1 to 6 .

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