JP4551377B2 - Deep-drawable sheet and method for producing the same - Google Patents

Description

  The present invention relates to a foamable formable sheet for deep-drawing molding that is excellent in processability and is composed mainly of synthetic pulp, wood pulp, and microcapsule particles having a property of foaming by heat. This formable sheet becomes a bulky molded product after foaming. More specifically, after deep drawing, it is used in applications such as heat insulating materials and automobile interior materials, and becomes a molded product having properties such as heat insulating properties, heat retaining properties and cushioning properties.

  Conventionally, high density polymer sheets such as foamed polystyrene and foamed polyethylene are used for applications such as heat insulating materials and automotive interior materials, which have low density, and have excellent heat insulation and heat retention, moldability, workability, and cushioning. Although it is good and inexpensive, it is used in large quantities. However, due to recent demands for preventing environmental pollution, it has been converted to paper that does not generate pollutants even if it is naturally decomposed or burned. It is being advanced.

Patent Document 1 has deep drawing suitability and molding holdability, excellent workability during hot press molding, opacity, oil resistance, water resistance, good flatness of the flange, and top seal suitability. For heat-resistant applications, even if a film is applied, the wood pulp content ratio is set to 51% by weight or more so that it can be treated as paper by the Containers and Packaging Recycling Law, and to provide molded products with high production efficiency. , N-BKP (softwood bleached kraft pulp), are compositions mainly of thermoplastic synthetic fibers and filler, and the surface layer, middle layer, the basis weight of 250 g / m ² or more multilayer paper making consists of backing layer, processing A technology for thermoforming molding paper having excellent properties is described. However, the density after deep drawing is about 0.5 g / cm ³ , which is a high density and does not have properties such as heat insulating properties, heat retaining properties, and cushioning properties.

Patent Document 2 aims to provide a foam particle mixed paper that is a low-density body and excellent in heat insulation, heat retention, impact resistance, cushioning properties, and the like. Although a method for producing a mixed paper having a density of 0.1 to 0.3 g / cm ³ by adding ~ 20 parts by weight, mixing and foaming during heating and drying is shown, in this case, the formability thereof is shown. Is not sufficient, and when performing deep drawing, which requires a large elongation during forming, the mixed paper breaks or wrinkles on the mixed paper, making it impossible to perform deep drawing.

Patent Document 3 aims to provide a foam particle mixed paper which is a low-density body and has excellent heat insulating properties, heat retaining properties, impact resistance, cushioning properties, etc., as in Patent Document 2, and the natural pulp is 50% by weight or more. In addition, 3 to 20 parts by weight of expandable particles are added to the fiber layer containing synthetic pulp and mixed to produce a mixed paper having a density of 0.1 to 0.3 g / cm ^3. ing. Even in the case of the blended paper of this document, when performing deep drawing that requires large elongation, the mixed paper can break or wrinkle on the mixed paper, and deep drawing can be performed. Absent.
JP 2006-022439 A Japanese Patent No. 3024591 Japanese Patent No. 3166663

  As mentioned above, deep-drawing that can be thermoformed to produce bulky deep-drawn molded products with properties such as heat insulation, heat retention, cushioning, etc. without causing problems as in the prior art There is no conventional technique for producing a conductive sheet.

  An object of the present invention is to produce a thermoformable formable sheet using an ordinary paper machine that makes it possible to produce a bulky deep-drawn molded product having properties such as heat insulation, heat retention, and cushioning. In addition, the present invention provides a deep-drawn formable sheet that is free from breakage and wrinkles when deep drawing is performed on a bulky formed body.

  As a result of repeated studies from the viewpoint of moldability and foamability, the present inventor has found that N-BKP (softwood bleached kraft pulp), thermoplastic synthetic fibers and foamable microcapsule particles are mainly composed of foamable thermoformable foam. The present inventors have surprisingly found that the above-described problems can be solved when the formable sheet is composed of multiple layers and foamed microcapsules are mainly mixed in the intermediate layer.

That is, the present invention relates to a thermoformable foamable formable sheet composed mainly of N-BKP (softwood bleached kraft pulp), thermoplastic synthetic fibers and expandable microcapsule particles, wherein the formable sheet is at least a surface layer. A multi-branched polyethylene-based synthetic sheet having a wood pulp content of 20% by mass to less than 51% by mass composed of one middle layer and a back layer, and the thermoplastic synthetic fiber having a melting point of 100 to 180 ° C. The blend ratio of the thermoplastic synthetic fibers of the front and back layers is 0 to 30% by mass, and the middle layer is 30 to 100% by mass. 10 to 50% by mass of expandable microcapsule particles that expand 4 to 5 times and the volume expands to 60 times or more, and the expandable microcapsule particles are used for the surface layer and the back layer. And up to 10 wt% blending less than or middle not blended, in a paper machine drying process, after drying without foaming the foamable microcapsule particles, subjected to calendering, taken up at a thickness of less than 1 mm, The present invention relates to a deep-drawn formable sheet characterized by becoming a bulky molded product having a density of 0.06 to 0.13 g / cm ³ after foaming .
In one embodiment of the present invention, the foamable microcapsule particles are added to the front and back layers of the moldable sheet in an amount of 1 to 10% by mass per 100% by mass of the fiber layer, and the mass of the fiber layer as a whole of the multilayer paper sheet is 100% by mass. The present invention relates to a deep-drawn formable sheet characterized in that the expandable microcapsule particles are 8 to 45% by mass per%.

  In one advantageous embodiment of the present invention, the present invention relates to a deep-drawn formable sheet characterized in that the thermoplastic synthetic fiber is a multi-branched polyethylene synthetic pulp having a melting point of 100 to 180 ° C.

  In one advantageous embodiment of the present invention, in the deep-drawn formable sheet, the added expandable microcapsule particles are heated by 100 to 220 ° C., about 4 to 5 times in diameter and 60 or more times in volume. Depending on the content of the expandable microcapsule particles and depending on the intended use, the thickness of the unfoamed multilayer paper sheet is preferably 4 to 8 times, particularly preferably 4 to 6 times the thickness. The present invention relates to a deep-drawn formable sheet characterized by being foamed and expanded.

  In one advantageous embodiment of the invention, the surface of the moldable sheet may be laminated with a polyethylene film, polypropylene film, polyester film, polybutylene terephthalate film, polymethylpentene film for heat resistant applications.

  In one advantageous embodiment of the present invention, as a method of foaming a deep-drawn formable sheet, the dried sheet is heated and foamed at a temperature of 100 to 220 ° C. with a clearance of a desired thickness by hot press molding. Then, there is a method of deep drawing.

  Further, there is also a method in which the deep-drawn formable sheet of the present invention is directly put into a deep-drawing molding machine and directly formed by heating at a temperature of 100 to 220 ° C. with a desired clearance.

In one advantageous embodiment of the present invention, the present invention relates to a deep-drawn molded article, wherein the formable sheet has a density after foaming of 0.1 g / cm ³ or less.

The formable sheet of the present invention can be deep-drawn without breakage or wrinkle when forming deep-drawn by a combination of wood pulp, thermoplastic synthetic fiber, and expandable microcapsule particles. Since it is 1 mm or less, it does not cause wrinkles or folds when wound on a reel, does not cause foaming unevenness, and has functions such as heat insulation, heat retention, and cushioning after foaming or after deep drawing. It has become possible to provide a molded article having a low density of 0.1 g / cm ³ or less, which is high and can be thermoformed.

  The present invention is a thermoformable multi-layer formable sheet in which wood pulp, thermoplastic synthetic fiber, and expandable microcapsule particles are mixed.

  The polyolefin synthetic pulp, which is the thermoplastic synthetic fiber in the present invention, is preferably a polyolefin synthetic pulp made of polyethylene or polypropylene having multi-branched fiber properties suitable for a wet papermaking process using a general-purpose paper machine. Moreover, what is excellent in the adhesiveness by heat fusion with a wood pulp by the heating at the time of shaping | molding is preferable, and the polyolefin-type synthetic pulp whose melting | fusing point is 100-180 degreeC is cheap, and is used suitably. For example, what is marketed under the trade name SWP from Mitsui Chemicals, Inc. can be used, but the present invention is not limited to this SWP.

  The form of these polyolefin-based synthetic pulps may be short fibers or long fibers as long as they can be made by a paper machine, but the average fiber length is preferably in the range of 0.1 to 10 mm. If it is less than 0.1 mm, it is difficult to form a sheet substantially with little entanglement between the fibers, and if it exceeds 10 mm, it is difficult to make a uniform sheet by papermaking.

  As the wood pulp used in the present invention, wood bleached chemical pulp typified by N-BKP (conifer bleach bleached kraft pulp) is mainly used. If necessary, mechanical pulp such as L-BKP (hardwood bleached kraft pulp), GP (crushed wood pulp), TMP (thermomechanical pulp), BCTMP (bleached chemithermomechanical pulp) and the like can be appropriately blended.

  The blending ratio of the thermoplastic synthetic fiber and the wood pulp in the moldable sheet of the present invention may be different between the front layer, the back layer and the middle layer. An appropriate blending ratio can be easily determined by a preliminary experiment while taking into account deep drawing suitability during thermoforming, shape stability of the molded body, workability, and the like.

  The blending ratio of the thermoplastic synthetic fiber in the moldable sheet of the present invention is 0 to 30% by mass, preferably 10 to 25% by mass in the surface layer and the back layer. If it is 30% by mass or more, it becomes easy to fuse to the mold during thermoforming, and the releasability is poor. Moreover, in a middle layer, it is 30-100 mass%, Preferably it is 40-90 mass%, More preferably, you may be 45-85 weight%. If it is less than 30% by mass, the suitability for deep drawing after thermoforming and the shape stability of the molded product are poor. Moreover, as a whole layer, the blending ratio of wood pulp is preferably 20% by mass to less than 51% by mass, preferably 30% by mass to less than 51% by mass, and particularly preferably 40% by mass to less than 51% by mass. When the wood pulp content is less than 20% by mass, a wet paper with sufficient strength cannot be obtained during paper making, and there is a risk of breakage.

  The expandable microcapsule particles used in the moldable sheet of the present invention are thermally expandable microcapsules in which a low-boiling solvent is enclosed in a microcapsule, and the diameter thereof is 4 by heating at a temperature of 80 to 220 ° C. for a short time. Particles having an average diameter of 5 to 40 μm that expand to 5 times and a volume of 60 times or more. Low boiling solvents include volatile organic solvents such as isobutane, pentane, petroleum ether, hexane, low boiling halogenated hydrocarbons, and methylsilane, and heat composed of copolymers such as vinylidene chloride, acrylonitrile, acrylic esters, and methacrylic esters. Wrapped with plastic resin. As these expandable microcapsule particles, for example, Expandel DU and WUF (made in Sweden, distributor Nihon Philite Co., Ltd.) can be used, but the present invention is not limited to these Expandel DU and WUF. Absent.

  The blending amount of the expandable microcapsule particles is 10 to 50% by mass, preferably 10 to 40% by mass, and more preferably 10 to 35% by mass per 100 parts by mass of the middle fiber layer of the moldable sheet. If it is less than 10% by mass, the density becomes high, and the heat insulating property, the heat retaining property and the cushioning property are deteriorated. If it exceeds 50% by mass, it is not very suitable from the viewpoint of economy. In addition, when it is put in the front and back layers, it is blended in a maximum of 10% by weight, preferably a maximum of 9% by weight, particularly preferably 8% by weight, per 100 parts by weight of the fiber layer of the front and back layers, and the amount thereof is the foamable microcapsule of the middle layer. Less than the amount of particles. If the amount of the particles in the front and back layers is more than 10% by mass, wrinkles may occur in the molded body during deep drawing. 8-45 mass% is mix | blended with respect to the whole fiber layer of a moldable sheet. When the blending amount of the foamable microcapsule with respect to the whole fiber of the moldable sheet is less than 8% by mass, the foaming amount is too small to achieve sufficient heat insulation, heat retention and cushioning properties, and exceeds 45% by mass. Therefore, it is impossible to obtain a sheet having sufficient strength.

  In the moldable sheet of the present invention, in addition to the pulp and expandable microcapsule particles, various yield improvers and paper strength improvers that are generally used within the range not impairing the object effects of the present invention. Further, chemicals such as an internal sizing agent, a pitch control agent, and an antifoaming agent can be used as appropriate.

  The formable sheet of the present invention is produced by a general multi-layer paper machine such as a long paper machine, a circular paper machine, or a long net and circular net combination machine.

  It is also possible to apply starch, polyvinyl alcohol, a surface sizing agent, a fluorescent whitening agent, etc. to the surface of the sheet by a coating method such as a size press or a gate roll on the formable sheet of the present invention.

The basis weight of the moldable sheet of the present invention is not particularly limited, but is usually in the range of about 200 to 600 g / m ² .

  The drying method before the foaming treatment is not particularly limited, and it is necessary to dry at 70 ° C. or less where foamable microcapsule particles do not foam in a normal cylinder dryer or the like.

  The calendering of the formable sheet of the present invention is performed for the purpose of processing the sheet to a thickness that can be taken up by a paper machine while making the sheet thickness uniform. Its thickness is 1 mm or less. For the calendar process, a machine calendar arranged on-machine, a super calendar, a gloss calendar, a brush calendar, a mat calendar, a soft calendar, and the like can be used, and the type of calendar is not particularly limited.

As one of the foaming methods of the moldable sheet of the present invention, there is a method in which the wound formable sheet before foaming is cut into a predetermined size, and this is press-heated from above and below with a target thickness clearance. It is done. Although the density in that case is not specifically limited, It is desirable that it is a low density, and it is desirable that it is 0.06-0.13 g / cm < ³ > especially. When the density is higher than 0.13 g / cm ³ , the foaming amount is insufficient, and the foamed molded article may lose characteristics such as heat insulation, heat retention and cushioning properties. The formable sheet after being cut and foamed can be satisfactorily deep drawn according to the purpose.

  Another method of foaming is a method of punching to a desired size and processing with a molding machine, molding with a molding machine at a predetermined thickness, and heating and foaming, but the molding time is long. There is a risk that the molding efficiency is lowered.

Example:
The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, unless otherwise indicated, the part and addition% in an example are a mass part or mass% in conversion of solid content.

<Manufacture of formable sheet>
As front and back layers, N-BKP / SWP (manufactured by Mitsui Chemicals, E620, multi-branched polyethylene synthetic pulp having a melting point of 135 ° C.) = 70/30% pulp was mixed, and Canadian Standard Freeness (hereinafter “Freeness”) Abbreviated.) 500 ml of pulp slurry was obtained, and rosin emulsion (AL-120 manufactured by Seiko PMC Co., Ltd., AL-120) as an internal sizing agent was 0.3% of pulp, sulfate band was 1% of pulp, and cationized starch (Japanese food) 1% of Neotac 40T manufactured by Kako Co., Ltd. was added, and the target basis weight of the front and back layers was set to 50 g / m ² with a circular net paper machine. As an intermediate layer, N-BKP / SWP (Mitsui Chemical Co., Ltd., E620) = 50/50% is blended to form a freeness 500 ml pulp slurry, and EXPANSEL 930- is used as expandable microcapsule particles per 100% by mass of the fiber layer. 25% by mass of 120DU (made in Sweden, distributor Nihon Philite Co., Ltd.) is added, and rosin emulsion (manufactured by Seiko PMC, AL-120) is used as an internal sizing agent. Add 1% cationized starch (Nippon Food Chemical Co., Neotack 40T) to 1% of pulp, and use a circular net paper machine to set the target basis weight of the two middle layers to 200 g / m ² respectively. and paper sheet at a target basis weight of 500 g / ^{m 2} by combined, dried with 70 ° C. at drier, multiplied by calendering, the thickness of 1mm Wound in a reel, to produce a molded sheet that has not been foamed expandable microcapsule particles.

<Adjustment of foamed bulky molded product>
The moldable sheet before foaming is cut into a size of 20 cm in length and 20 cm in width, and a heat press (Mini Test Press-10, manufactured by Toyo Seiki Co., Ltd.) is used with a clearance of 6 mm and a temperature above and below the press of 200 ° C. , Pressed for 1 minute to obtain a bulky molded body in which the foamable microcapsule particles were foamed.

The basis weight, thickness, and density in the examples of the present invention were visually evaluated for the presence or absence of uneven foaming and moldability in accordance with the following JIS.
a. Basis weight: JIS P 8124
b. Thickness and density: JIS P 8118
c. Foaming unevenness: Visual evaluation ○: No foaming unevenness, at practical level.
Δ: Some foaming unevenness is not practical.
X: There is foaming unevenness and it cannot endure practical use.
d. Deep drawability: Using a tray molding machine with a depth of 10 mm, male and female dies are set, and continuous molding is performed at a temperature (180 ± 5) ° C., a press pressure of 50 kg / cm ² , a clearance of 5 mm, and a press time of 10 seconds. In addition, deep drawing aptitude such as material destruction and wrinkle generation and shape stability of the molded body were comprehensively evaluated.
○: Good and practical level.
Δ: Slightly inferior and not practical.
X: Inferior and not practical.

Example 1 except that 8% by mass of EXPANCEL 007-40WUF (made by Sweden, distributor Nihon Philite Co., Ltd.) is added as foamable microcapsule particles to the front and back layers of Example 1 per 100% by mass of the fiber layer. Similarly, a four-layered sheet is used to form a sheet at a basis weight of 500 g / m ² , dried at 70 ° C. with a dryer, wound up with a reel, and a foamable microcapsule particle is not foamed. In the same manner as in Example 1, a bulky molded body in which foamable microcapsule particles were foamed was obtained by hot pressing.

In the base paper of Example 1, Example 1 except that 30% by mass of EXPANCEL 930-120DU (manufactured by Sweden Philly Co., Ltd.) was added as expandable microcapsule particles per 100% by mass of the fiber layer in the middle layer. In the same manner as above, a sheet is made at a target basis weight of 500 g / m ² by 4 layers, and dried at 70 ° C. with a dryer, reeled up, and foamable microcapsule particles are not foamed. A sheet was obtained, and a bulky molded article obtained by foaming expandable microcapsule particles was obtained by hot pressing in the same manner as in Example 1.

[Comparative Example 1]
In Example 1, it was the same as Example 1 except that 9% by mass of EXPANCEL 930-120DU (made by Sweden, distributor Nihon Philite Co., Ltd.) was added as expandable microcapsule particles per 100% by mass of the fiber layer in the middle layer. Then, a sheet having a target basis weight of 500 g / m ² is made by four-layer sheeting, dried at 70 ° C. with a dryer, wound with a reel, and a formable sheet in which foamable microcapsule particles are not foamed is obtained. In the same manner as in Example 1, a bulky molded body in which foamable microcapsule particles were foamed was obtained by hot pressing.

[Comparative Example 2]
In Example 1, dried at 70 ° C. with a dryer, wound with a reel at a thickness of 1.5 mm without applying a calendar, to obtain a formable sheet without foaming the foamable microcapsule particles, A bulky molded body obtained by foaming expandable microcapsule particles was obtained by hot pressing in the same manner as in Example 1.

[Comparative Example 3]
In Example 1, N-BKP / SWP (Mitsui Chemical Co., Ltd., E620) = 50/50% blended pulp of the front and back layers was mixed in the same manner as in Example 1 except that the target basis weight was obtained by combining the four layers. A sheet is made at an amount of 500 g / m ² , dried at 70 ° C. with a dryer, wound up with a reel, and a formable sheet in which foamable microcapsule particles are not foamed is obtained. Thus, a bulky molded body obtained by foaming expandable microcapsule particles was obtained.

  These results are shown in Table 1.

  As is clear from the results of the table and the examples, the moldable sheet of the present invention is a multilayer paper sheet mainly composed of wood pulp, thermoplastic synthetic fibers, and expandable microcapsule particles. By producing a thermoformable formable sheet of 8 to 45% by mass with respect to the fiber layer, it has a relatively low density, and has properties such as heat insulation, heat retention and cushioning, and deep drawability. It became possible to provide a formable sheet provided with

Specifically, when the blending ratio of the foaming agent in the middle layer of Comparative Example 1 is 9%, the thickness after foaming is 3.2 mm (3.2 times), the amount of foaming is small, and the density is 0.157 g / cm ³ . Since it is high, heat insulating properties, heat retaining properties and cushioning properties are insufficient. Further, in Comparative Example 2, when the thickness of the dry sheet not foamed with the foamable microcapsule particles exceeds 1.5 mm and 1 mm, wrinkles and folds are generated by winding on the reel, and foaming unevenness is also generated. However, the suitability for deep drawing is inferior and there is a problem in moldability. Furthermore, in Comparative Example 3, when the ratio of the thermoplastic synthetic fibers in the front and back layers is increased to 50%, it sticks to the mold at the time of thermoforming, and is difficult to come off, resulting in poor moldability.

  As described above, the formable sheet of the present invention is composed of a multi-layered paper mainly composed of a specific amount of wood pulp, thermoplastic synthetic fibers, and expandable microcapsule particles, and mainly has expandable microcapsules in the middle layer. Enables deep drawing without breakage and wrinkling of the mixed paper when forming deep drawing, and the molded bulky product has shape stability, heat insulation, heat retention, cushioning, etc. It was found that it has the characteristics of

Claims (3)

Thermoformable foamable formable sheet composed mainly of N-BKP (softwood bleached kraft pulp), thermoplastic synthetic fiber and expandable microcapsule particles, wherein the formable sheet is a surface layer, at least one middle layer, It is a multilayer paper sheet having a wood pulp content of 20% by mass to less than 51% by mass composed of a back layer, and the thermoplastic synthetic fiber is a multi-branched polyethylene synthetic pulp having a melting point of 100 to 180 ° C., The blending ratio of the thermoplastic synthetic fibers of the front and back layers is 0 to 30% by mass, 30 to 100% by mass in the middle layer, and the diameter of the middle layer is about 4 to 5 times per 100% by mass of the fiber layer by heating and 10 to 50% by mass of expandable microcapsule particles whose volume expands 60 times or more, and whether or not the expandable microcapsule particles are added to the surface layer and the back layer Up to 10 wt% blending less than middle, in a paper machine drying process, drying without foaming the foamable microcapsule particles, subjected to calendering, taken up at a thickness of less than 1 mm, after foaming 0.06 A deep-drawn formable sheet characterized by being a bulky molded product having a density of ˜0.13 g / cm ³ .     The foamable microcapsule particles are added to the front and back layers of the moldable sheet in an amount of 1 to 10% by weight per 100% by weight of the fiber layer, and the foamable microcapsule particles per 100% by weight of the fiber layer as the whole multilayer sheet. The deep-drawn formable sheet according to claim 1, wherein the content is 8 to 45% by mass. The deep-drawn formable sheet according to claim 1 or 2 , wherein the formable sheet is heated and foamed by hot pressing at 100 to 220 ° C.