JPH05230798A - Production of bulking paper - Google Patents

Abstract

PURPOSE:To obtain a bulking paper having excellent heat-insulation and cushioning property by making a base paper from pulp and foamable particles and foaming the paper under specific condition. CONSTITUTION:A foamed base paper having a density of as low as 0.05-0.3g/cm which is comparable to that of foamed styrene can be produced by mixing a pulp with 1-40wt.% (preferably 3-20wt.%) of foamable particles, making a base paper from the mixture and foaming the obtained paper in hot water of >=90 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing low-density bulky paper having foam particles mixed therein, and more specifically, a heat insulating property which can be used as various heat insulating materials and cushioning agents,
The present invention relates to a method for producing low-density paper mainly composed of pulp having excellent heat retention.

[0002]

2. Description of the Related Art Conventionally, high-molecular polymers such as expanded polystyrene and expanded polyethylene have been mainly used as various heat insulating materials and cushioning materials, but they naturally collapse or burn to prevent environmental pollution these days. Even so, switching to paper base materials that are less likely to generate pollutants and black smoke is being promoted.

In order to provide such a paper substrate with effective heat insulating properties and cushioning properties, it is the most effective method to provide the paper with an air layer close to closed cells. As a method of giving bubbles close to closed cells, by providing a coating layer containing hollow capsules, after coating the expandable capsules, a method of foaming to lower the density, foaming capsules with pulp papermaking There is a method of foaming on a hot roll of a paper machine. Of these, in order to obtain a foamed paper that is truly effective for heat insulation, etc., hollow capsules can be mixed or foamed by a method in which a foaming agent is applied to the coating layer so that only some layers are in a foamed state. It is desirable to make the entire paper in a foamed state by a method such as mixing paper with paper and distributing it over the paper.

However, among the above methods, the method of mixing hollow capsules and the like is not a very practical method because the difference in specific gravity between the pulp and the hollow capsule is so great that it is difficult to mix them uniformly and uniformly. That is, Japanese Patent Application Laid-Open No. 52-39924 discloses a method for producing bulky paper by adding shirasu balloon during papermaking, but since shirasu balloon floats in water due to its low specific gravity, papermaking is not performed. There is a difficult problem.
The density of the base paper obtained was 0.37 to 0.67 g / cm ³ as can be seen from the table shown in the example, and the density for obtaining our target characteristics similar to those of expanded polystyrene was obtained. Has not been done. On the other hand, Japanese Patent Application Laid-Open No. 47-24263 discloses a method of mixing foamable plastic with fibers. As can be seen from Example 1, 6 g of pulp and 30 g of plastic are mainly composed of foamable plastic. This is an invention that is different from the sheet mainly made of paper.

As a method of using the expandable capsule,
Japanese Unexamined Patent Publication No. 55-18116 discloses a diaphragm prepared by mixing microcapsules. The density of the resulting board is about 0.5 g / cm ^3, which is low for the purpose of the present invention. Density is not obtained.

Regarding the method of using the expandable capsule, for example, Japanese Patent Laid-Open No. 173686/1988 describes a method of foaming on a heat roll of a papermaking machine in the production of base paper for thermal paper. Has a density of 0.5 g / cm ³
The density is reduced only to some extent, which is insufficient for obtaining effective heat insulating properties and cushioning properties. That is, the thermal conductivity of styrofoam normally used as a heat insulating material is 0.
Although it is as small as 045 w / m / k, it has a very high thermal conductivity of 0.07 w / m / k when it is used as a base paper with a density of 0.5 g / cm ³ using the above-mentioned foam capsule, and is still a heat insulating material. It turned out to be insufficient.

As described above, a low density paper base material having properties such as heat insulating properties, heat retention properties and strength equivalent to those of expanded polystyrene has not yet been known, and its development is desired. Further, there is a demand for a container mainly composed of such a paper base material.

That is, the foaming agent containing a liquid as a core substance needs to be heat-treated at an appropriate temperature for causing foaming. For example, in the case of Matsumoto Yushi Co., Ltd.'s Matsumoto Microsphere F30, the expansion ratio in terms of the volume expansion coefficient of the foamed material reaches a maximum at 130 to 140 ° C. in a heating time of 1 minute (about 80 times), while 110 ° C. Alternatively, it is described that at 160 ° C., the foaming ratio is already around 40 times and effective foaming cannot be obtained.

The present inventors have prepared a sheet of 100 g / m ^{2 obtained} by adding 10% of this microsphere to pulp.
As a result of performing a heat foaming test at an initial setting temperature of 95, 105, 130, 150 ° C. for 3 minutes using a rotary dryer manufactured by FC Manufacturing Co., Ltd., the density of the obtained base paper (measured by JIS) was 0. 38, 0.30, 0.24
It became 0.18 g / cm ³ , and it was found that a base paper having a considerably low density can be obtained at 130 ° C. or higher.

However, it has been found that the base paper foamed at a temperature of 130 ° C. or higher has some small pox-like portions which seem to be unfoamed, and a uniform foamed paper cannot be obtained. It was found that the cause was that the capsule was broken and foaming was not sufficiently obtained, or that the surrounding area was foamed first, so that the capsule could not be contacted with the heat source and could not be foamed.

When a foamed paper is obtained by post-heating from a sheet obtained by mixing a foaming agent containing a liquid as a core substance with pulp in this way, it is generally at a suitable temperature of a dryer of 70 to 130 ° C. which is a dryer in the step of drying the paper making process. Then the density of the base paper is 0.05 to 0.3
It is difficult to produce a low-density foamed base paper of g / cm ³ uniformly, and it is possible to obtain a high-foamed base paper that can obtain a high temperature of 110 to 150 ° C., for example, even if a paper machine with a Yankee dryer is used. Was found to have problems such as the formation of smallpox-like unevenness.

[0012]

DISCLOSURE OF THE INVENTION According to the present invention, a sheet made from a foam material containing a liquid as a core substance is heated and foamed to have the same density as expanded polystyrene having a density of 0.05 to 0.3 g / cm ^3. The present invention provides a method for producing bulky paper having excellent heat insulating properties and cushioning properties.

[0013]

[Means for Solving the Problem] When the present inventors produce a low-density bulky paper by foaming a base paper obtained by mixing pulp and expandable particles by heating,
A low-density bulky paper having a low density of 0.05 to 0.3 g / cm ³ could be obtained by foaming the expandable particles by bringing them into contact with high temperature water of 0 ° C. or higher.

It is not known why good stable foaming can be obtained at a temperature considerably lower than the suitable temperature range indicated in the catalog, but when impregnated in hot water, heating contact occurs. It can be understood that the base paper is uniformly foamed so that the base paper is uniformly foamed.

For example, when the 100 g / m ² microsphere-blended paper was dipped in hot water at 96 ° C. for 3 seconds, a low-density foam base paper with a density of 0.17 g / cm ³ was obtained. The heat conductivity of this base paper was measured and found to be 0.0
It was 38 w / m / k, which was as good as that of expanded polystyrene and was uniform.

As described above, it has been found that a foamed base paper having good heat insulation or cushioning properties, which can be replaced with expanded polystyrene, expanded polyethylene or the like, can be obtained by using the foamed base paper mainly composed of pulp.

Such hot water of 90 to 100 ° C. is relatively easy to use industrially, and is suitable for industrially producing a foamed base paper having a uniform surface. That is, by heating the water in a container with a jacket in which the bottom of a flat-bottomed container is doubled so that steam can pass therethrough, hot water of 90 to 100 ° C. is obtained, and the foaming base paper is passed through this. It can also be done in a deep-jacketed container as well. Also, by blowing steam into the hot water tank, hot water of around 100 ° C. can be produced, and by blowing steam directly into a pan containing hot water to be foamed, a temperature of 90 to 100 ° C. can be obtained. Further, hot water can be similarly obtained by blowing steam directly into the pipe for supplying hot water to the pan to be foamed.

Various devices can be used as the device for performing the foaming treatment. That is, in a flat tray-shaped or flat box-shaped container, the hot water is foamed in parallel or opposite to the base paper so that the hot water is made to come into contact and foamed, or the hot water is circulated in a deep vertical container and the paper is reciprocated therein. Can be contacted and foamed. Then, instead of circulating hot water in the above-described device, steam is blown directly into the hot water in the container.
It is possible to obtain an apparatus equipped with hot water of -100 ° C. In addition, a method of supplying hot water to the upper depressions of two rolls having a large diameter (for example, a size press of a paper machine) and running the paper through the gap between the rolls from above or below to bring the paper into contact with hot water to foam Can be considered.

Next, the present invention will be described in detail.

Papermaking of the base paper to be foamed is carried out by adding 1 to 40 foams containing a liquid as a core substance to a fiber material mainly composed of pulp.
%, Wet paper strength agent, dry strength agent, sizing agent, filler,
First, a wet paper web is manufactured by adding pigments and the like as needed. This is dehydrated with a press to a water content of about 60% as usual and dried with a dryer. However, the drying temperature at this time is preferably 100 ° C. or lower. This is to prevent the foaming agent from being foamed unnecessarily. It is appropriate that the dry base paper has a water content of about 50 to 2%, that is, the base paper is not destroyed or damaged by the hot water foaming treatment in the subsequent step. Next, it is contacted with hot water at 90 to 100 ° C. for about 1 to 10 seconds to foam the foam, and then dried by a dryer at 100 ° C. or less to produce a foam base paper.

The pulp used is not particularly limited, but examples of the pulp used in the present invention include wood pulp such as chemical pulp and mechanical pulp of softwood and hardwood, waste paper pulp, non-wood natural pulp such as hemp and cotton. Examples thereof include synthetic pulps made of polyethylene, polypropylene, etc. as raw materials, and these are appropriately used in combination. In addition to the above pulp, acrylic fiber, rayon fiber, phenol fiber,
It is also possible to mix various fibers such as organic fibers such as polyamide fibers and polyester fibers, inorganic fibers such as glass fibers, carbon fibers and alumina fibers. However, from the viewpoint of paper-making properties, it is advantageous that the pulp is blended in an amount of 50% or more because the sheet texture and strength are excellent. As a fiber blend, it is preferable to use at least 5 to 20% of a softwood pulp or a synthetic pulp having a long fiber length because it has a strength against hot water.

As the foaming agent, heat-expandable microcapsules in which a low boiling point solvent is enclosed in microcapsules are used. This capsule has a diameter of about 4 to 5 times and a volume of 50 to 50 by heating at a relatively low temperature of 80 to 200 ° C for a short time.
These particles have an average particle size of 10 to 30 μm and expand 100 times. Isobutane, pentane, petroleum ether, hexane,
A volatile organic solvent (swelling agent) such as low-boiling halogenated hydrocarbons and methylsilane is wrapped in a thermoplastic resin consisting of a copolymer of vinylidene chloride, acrylonitrile, acrylic ester, etc., and the capsule softens the polymer. When heated above the point, the film polymer begins to soften, the vapor pressure of the encapsulating expander rises, the film expands, and the capsule expands. It expands at a relatively low temperature in a short time to form closed cells, and can provide excellent heat insulation.

The content of the expandable particles is 1 to 40% by weight, preferably 3 to 20%, and 1% by weight based on the pulp fiber.
In the following, sufficient foaming cannot be obtained, and in the case of 40% or more, it is not so suitable from the economical aspect.

In addition to these expandable particles, various types of conventionally used anionic, nonionic, cationic or amphoteric retention aids, paper strength enhancers, sizing agents, etc. are appropriately selected for the pulp slurry. Can be used. The zeta potential of the papermaking raw material is -15 mV to 10 mV in order to improve the yield of the foaming agent during papermaking.
Is preferred. The following are specific examples of chemicals that can be used. Paper strength enhancers and retention aids include polyacrylamide-based cationic, nonionic, anionic and amphoteric resins, polyethyleneimine and its derivatives, polyethylene oxide, polyamines, polyamides, polyamide polyamines and their derivatives, cationic and Amphoteric starch, oxidized starch, caboxymethylated starch, plant gum, polyvinyl alcohol, urea formalin resin, melamine formalin resin, organic compounds such as hydrophilic polymer particles, and sulfuric acid band, alumina sol,
Aluminum compounds such as basic aluminum sulfate, basic aluminum chloride and basic polyaluminum hydroxide, and further inorganic compounds such as ferrous sulfate, ferric chloride or colloidal silica and bentonite are used in appropriate combination.

As the sizing agent, various sizes such as rosin-based sizing agent, petroleum resin-based sizing agent as acidic papermaking sizing agent, alkyl ketene dimer-based sizing agent and alkenyl succinic anhydride-based sizing agent as neutral papermaking sizing agent An agent can be mentioned.

In the pulp slurry in which the expandable particles are mixed, generally known fillers such as talc, kaolin, calcined kaolin, clay, diatomaceous earth, ground calcium carbonate, magnesium carbonate, aluminum hydroxide, titanium dioxide, Mineral filler such as magnesium sulfate, silica, aluminosilicate, bentonite and polystyrene particles,
Organic synthetic fillers such as urea formalin resin particles can be appropriately selected and used in combination.

Further, a papermaking additive such as a dye, a pH adjusting agent, a slime control agent, a defoaming agent, and a sticky agent can be appropriately used according to the intended use.

It is also possible to apply starch, polyvinyl alcohol, various surface sizing agents, pigments, etc. to the surface of the sheet by a coating method such as a size press or a gate roll.

The above constituent raw materials are used as main raw materials and formed into a sheet by an ordinary papermaking machine. First, it is dried by a dryer part, but due to the surface temperature of this dryer part, the expandable particles mixed in the sheet are foamed at the same time as the drying, and a large number of closed cell bands are formed in the sheet base material. Is low and the sheet has excellent heat insulation.

Here, the basis weight of the sheet is 25 to 400 g /
m ^2, and a basis weight of not have sufficient heat insulation sheet is obtained with 25 g / m ² or less, the load on the dryer the drying process of the paper machine is 400 g / m ² or more is too large enough No heat treatment is obtained, and the expandable particles do not sufficiently expand. However, it is within the scope of the present invention to use a paper having a low basis weight of 100 g / m ² or less, which is used in the same manner as the case where the basis weight is increased.

Next, the foaming treatment with hot water will be described.

First, as the first manufacturing method of the present invention,
After being formed into a sheet by the wire part in the papermaking process, it is dehydrated by the press part, and the water content is dropped to about 60% of the papermaking base paper here in order to facilitate subsequent drying. Then, it is dried with a multi-cylinder dryer to dry the moisture to 50 to 5%, and put in a hot water foaming device at 90 ° C or higher. When the amount of water is large, it is preferable to place it on a conveying device such as a belt in the foaming device for foaming so that paper breakage is reduced. If it is dried up to around 10%, there will be little paper breakage as it is, but if the softwood pulp content is increased to 20% or more and a polyamide paper polyamine and its derivative wet paper strength additive is added, there will be almost no problems with paper breakage. Next, the foamed wet paper is dried to a water content of 10% by a multi-cylinder dryer, an air blow dryer or the like and wound up. When the base paper is thick, it is possible to cut it into sheets using a sheet cutter online.

As a second method, the paper is made by the above-mentioned method, and the unfoamed paper is wound up. It is put into a foaming device of hot water of 90 ° C. or higher to foam, and then dried.

To dry the wet paper web in the present invention, it is necessary to prevent excess foaming of the foam when drying the wet paper web before foaming, and it is necessary to dry the wet paper web after foaming. Is 7
It is necessary to carry out the treatment at 0 to 120 ° C. and raise the temperature so high that the shrinkage of the foam does not occur.

In this way, the volume of pulp is reduced to 1 by heating.
A low-density base paper with a uniform density of 0.05 to 0.3 g / cm ³ is obtained by foaming a base paper mixed with capsules containing a core substance of a liquid that increases from 0 to 100 times with hot water at 90 ° C. or higher. A method of manufacturing is obtained.

[0036]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In the following,% is% of weight
Indicates.

Example 1 80% of hardwood bleached pulp (LBKP) beaten to 420 ml of Canadian standard freeness (CSF) and Canadian standard freeness (C)
SF) Softwood bleached pulp (NBK) beaten to 420 ml
P) 20% pulp was dispersed in a pulp slurry to form expandable microcapsule particles (Matsumoto Yushi-Seiyaku Co., Ltd.).
Made by Matsumoto Microsphere F-30D, particle size 1
0 to 20 μm, maximum foaming temperature 130 ° C.) 10%, dry paper strength enhancer (Arakawa Chemical Industry Co., Ltd., Polystron 11)
7) 0.2%, cationized starch (Oji National Co.,
CATO-15) 1.0%, alkyl ketene dimer sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd., Size Pine K90)
3) 0.07% and 0.4% of wet paper strength enhancer (Kaimen 557H, manufactured by DIC Hercules Co., Ltd.) were added with good stirring to obtain a papermaking raw material having a pulp concentration of 0.5%.

The papermaking material thus obtained was used to make paper with a Fourdrinier paper machine at a basis weight of 300 g / m ² and a machine speed of 25 m / min, and was dried with a multi-cylinder dryer having a surface temperature of 80 ° C. and a water content of 58%. Then, it was made to be 11%, and subsequently, a tab-sized flat-bottom tray was provided with a lid, and a heat insulating material was further applied to the whole to keep it warm, followed by foaming through a foaming device containing hot water of 95 ° C. Next, 10% water content with a multi-cylinder dryer with a surface temperature of 105 ° C.
It is dried and wound on a take-up reel with a diameter of 70 cm.
A low density foam base paper was obtained.

The foaming apparatus used here had a length of 8 m, and hot water was produced by blowing 4 kg / cm ² of steam into a tank to produce hot water at 98 ° C. and supplying it to the tray. Part of the hot water was circulated. Then, according to JIS, the basis weight, the thickness, and the density were measured, and the presence or absence of uneven foaming was visually evaluated.

Example ² A sheet having a basis weight of 302 g / m ² was made using the same papermaking material and apparatus as in Example 1 except that the temperature of hot water was 90 ° C.

Comparative Example 1 A sheet having a basis weight of 302 g / m ² was made using the same papermaking raw material and apparatus as in Example 1 except that the temperature of hot water was 80 ° C.

Comparative Example 2 The same papermaking raw material as in Example 1 was used, and the basis weight was 30 using a Fourdrinier paper machine.
Foaming base paper with 1 g / m ² and 58% water content at a machine speed of 25 m / min, foamed and dried with a multi-cylinder dryer with a surface temperature of 120 ° C., and a 8% water content without using a tab size foaming device. Paper was made.

Example 3 Using the same papermaking raw material and apparatus as in Example 1 except that the pulp content was LBKP 70% and NBKP 30%, the basis weight was 5
A 2 g / m ² sheet was made into paper. Example 4 The same papermaking raw material as in Example 1 was used, and the basis weight was 30 using a Fourdrinier paper machine.
Paper was made at 0 g / m ² and a machine speed of 25 m / min, dried with a multi-cylinder dryer having a water content of 58% and a surface temperature of 75 ° C. so as not to foam, and an unfoamed base paper having a water content of 10% was made. After that, foaming and drying were performed in an off-line impregnation device. That is, a 5 m long tab size impregnation part was foamed with hot water of 95 ° C. as a hot water foaming device similar to that of Example 1, and dried with a blow dryer at 10 m / min to a water content of 10%. It was

The above results are shown in Table 1.

[0045]

[Table-1]

[0046]

As can be seen from the results of the above examples, according to the production method of the present invention, a base paper mainly composed of pulp and a foamable capsule whose core substance is a liquid whose volume is increased 10 to 100 times by heating is prepared. In the method for producing bulky paper by foaming by heating, the base paper is brought into contact with high temperature water of 90 ° C. or higher to foam the capsules in the base paper to obtain a low density paper of 0.05 to 0.3 g / cm ^3. was gotten.

By the method of contacting the base paper internally containing the heat-expandable particles with the high temperature water of 90 ° C. or higher according to the present invention, a uniformly expanded low density bulky paper having a density of 0.05 to 0.3 g / cm ³ can be obtained. Was obtained.

Since the expandable base paper having such characteristics is mainly composed of natural materials, it does not generate a large amount of soot or almost no odor when incinerated like expanded polystyrene, and it does not generate much odor. As described above, an excellent low-density foamed paper can be obtained without generating a large amount of heat and damaging the furnace.

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Claims (1)

[Claims] 1. A method for producing a low-density bulky paper by heating a base paper obtained by making paper from pulp and expandable particles by heating to bring the base paper into contact with high-temperature water at 90 ° C. or higher. To expand the expandable particles, the density is 0.05 ~
A method for producing bulky paper, which comprises obtaining bulky paper having a low density of 0.3 g / cm ³ .