JP2008050724A - Deep drawn moldable paper and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a thermoformable moldable paper enabling the production of a bulky deep draw molded article having characteristics such as heat insulating property, warmth-keeping property, cushioning property, etc., and also not causing breakage/wrinkles on deep draw-molding of a bulky formed article. <P>SOLUTION: The deep drawn moldable paper which is a foamable and moldable paper capable of being thermally molded, consisting mainly of an N-BKP (needle leaf tree-bleached kraft pulp), a thermoplastic synthetic fiber and expandable microcapsule particles, wherein the moldable paper is a multi-layered paper consisting of a surface layer, a middle layer and a reverse surface layer, having a wood pulp blending ratio of ≥51%, blending 10 to 40 mass% expandable microcapsule particles expanding approximately 4 to 5 folds in diameter and ≥60 folds in volume by heating, based on 100 mass% fibrous layer in the middle layer, the expandable microcapsule particles are not blended in the surface and reverse surface layers or the maximum 10 mass% of the microcapsule particles are blended in the middle layer so as to be less than those in the middle layer, the mixture is dried without foaming the micro capsule particles in the drying process of a papermaking machine, calendared and then wound into a thickness of ≤1 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a foamable formable paper for deep-drawing that can be thermoformed and is excellent in processability, which is mainly composed of synthetic pulp, wood pulp, and microcapsule particles having a property of foaming by heat. This formable paper 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 quality paper.

  An object of the present invention is to produce a thermoformable formable paper 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 properties. Moreover, it is an object of the present invention to provide the deep-drawn formable paper that is free from breakage and wrinkles when deep drawing is performed on a bulky formed body. In addition, the object of the present invention is to provide a formable paper that can be handled as paper by the Containers and Packaging Recycling Law, even when a film is pasted, for a heat resistant application, by setting the blending ratio of wood pulp to 51% by mass or more. is there.

  As a result of repeated investigations from the viewpoint of moldability and recyclability, the present inventor has conducted thermoforming foaming composed mainly of N-BKP (softwood bleached kraft pulp), thermoplastic synthetic fibers, and foamable microcapsule particles. It has been found that the above-mentioned problem can be solved surprisingly when the formable paper 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 paper composed mainly of N-BKP (softwood bleached kraft pulp), thermoplastic synthetic fibers and expandable microcapsule particles, wherein the formable paper is at least a surface layer. It is a multilayer paper having a wood pulp blending ratio of 51% or more, consisting of one middle layer and a back layer. The diameter of the middle layer is about 4 to 5 times and the volume is 60 times per 100 mass% of the fiber layer by heating. 10 to 40% by mass of expandable microcapsule particles that expand more than twice, and the surface layer and the back layer are not compounded with the expandable microcapsule particles or less than the middle layer and are compounded up to 10% by mass. In a drying process, the foamable microcapsule particles are dried without being foamed, then applied to a calendar, and taken up to a thickness of 1 mm or less, and the deep-drawn formable paper .

In one embodiment of the present invention, the foamable microcapsule particles are added to the front and back layers of the formable paper in an amount of 1 to 10% by mass per 100% by mass of the fiber layer, and the mass of the fiber layer is 100% by mass as the entire multilayer paper. The present invention relates to a deep-drawn formable paper characterized in that the expandable microcapsule particles are 9 to 35% by mass per%.

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

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

  In one advantageous embodiment of the invention, the surface of the formable paper 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 deep-drawn formable paper, the dried sheet is heated and foamed at a temperature of 100 to 220 ° C. with a clearance of the 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 paper of the present invention is directly put into a deep-drawing machine and directly formed by heating at a temperature of 100 to 220 ° C. with a clearance of a desired thickness.

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

The formable paper of the present invention can be deep-drawn without breakage or wrinkles when deep-drawn by using a combination of wood pulp, thermoplastic synthetic fibers, 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 low-density molded body of less than 0.1 g / cm ^{3 that} can be thermoformed in a field that is high and that is handled as paper by the Containers and Packaging Recycling Law.

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

  The polyolefin synthetic pulp which is a thermoplastic synthetic fiber in the present invention is preferably a polyolefin synthetic pulp made of polyethylene or polypropylene having a multi-branched fiber property 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 formable paper 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 formable paper 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, the mixture rate which makes the mixture rate of a wood pulp 51 mass% or more as a whole layer is preferable.

  The expandable microcapsule particles used in the formable paper 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, sold by Nihon Philite Co., Ltd.) can be used, but the present invention is limited to these Expandel DU and WUF. is not.

  The blending amount of the expandable microcapsule particles is 10 to 40% by mass, preferably 10 to 38% by mass, and more preferably 10 to 35% by mass per 100 parts by mass of the middle fiber layer of the formable paper. 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 40% 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. 9-35 mass% is mix | blended with respect to the whole fiber layer of a formable paper. When the blending amount of the foamable microcapsule with respect to the whole fiber of the formable paper is less than 9% by mass, the foaming amount is too small to achieve sufficient heat insulation, heat retention and cushioning properties, and exceeds 35% by mass. Therefore, it is not possible to obtain a sufficiently strong paper.

  In the formable paper 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 a range that does not impair 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 paper of the present invention is produced by a general multi-layer paper machine such as a long paper machine, a circular paper machine, and 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 paper by a coating method such as a size press or a gate roll on the formable paper of the present invention.

The basis weight of the formable paper 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 paper of the present invention is performed for the purpose of processing the paper to a thickness that can be taken up by a paper machine while making the paper thickness uniform. Its thickness is 1 mm or less. For the calendar processing, 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. The type of calendar is not particularly limited.

As one of the foaming methods of the formable paper of the present invention, the wound formable paper before foaming is cut into a predetermined size, and this is performed by deep drawing with a hot press machine such as a hot press. There is a method of press heating from above and below with a clearance of a certain thickness. 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 foam molded article may lose characteristics such as heat insulation, heat retention, and cushioning properties.

  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 paper>
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-based 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 90 g / m ² with a round 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. 120 DU (made in Sweden, Nihon Philite Co., Ltd.) 25% by mass was added, and rosin emulsion (manufactured by Seiko PMC, AL-120) was used as an internal sizing agent. Add 1% of pulp and 1% of cationized starch (Neotac 40T, manufactured by Nippon Shokuhin Kako Co., Ltd.) to pulp, and set the target basis weight of the two middle layers to 135g / m ² on a round net paper machine. paper making paper by the target basis weight 450 g / m ² by alignment can, dried at 70 ° C. at drier, multiplied by calendering, Lee at 1mm thick Wound in, to produce the moldability paper that has not been foamed expandable microcapsule particles.

<Adjustment of foamed bulky molded product>
The formable paper 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. , And pressed for 1 minute to obtain a bulky molded product obtained by foaming expandable microcapsule particles.

  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.

Except for adding 100% by mass of EXPANCEL 007-40WUF (made by Sweden, distributor Nihon Philite Co., Ltd.) as expandable microcapsule particles to the front and back layers of Example 1 per 100% by mass of the fiber layer. In the same manner as in Example 1, paper was made at a basis weight of 450 g / m ² by four-layer making, dried at 70 ° C. with a dryer, wound on a reel, and foamed microcapsule particles were not foamed. A formable paper was obtained, and a bulky molded body in which foamable microcapsule particles were foamed was obtained by hot pressing in the same manner as in Example 1.

In the base paper of Example 1, Example except that 30% by mass of EXPANSEL 930-120DU (manufactured by Sweden Philharmonic 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 in No. 1, paper is made at a target basis weight of 450 g / m ² by four-layer making, dried at 70 ° C. with a dryer, wound on a reel, and foamed microcapsule particles are not foamed. A formable paper was obtained, and a bulky molded body in which foamable microcapsule particles were foamed was obtained by hot pressing in the same manner as in Example 1.

Comparative Example 1

Example 1 is the same as Example 1 except that 9% by mass of EXPANSEL 930-120DU (made by Sweden, distributor Nihon Philite Co., Ltd.) is added as expandable microcapsule particles per 100% by mass of the fiber layer in the middle layer. In the same manner, paper having a target basis weight of 450 g / m ² is made by four-layer making, dried at 70 ° C. with a dryer, wound with a reel, and foamable microcapsule particles are not foamed. Paper was obtained, and a bulky molded body in which foamable microcapsule particles were foamed was obtained by hot pressing in the same manner as in Example 1.

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 paper 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. Paper is made at an amount of 450 g / m ² , dried at 70 ° C. with a dryer, wound with a reel to obtain a formable paper in which the foamable microcapsule particles are not foamed, and hot-pressed as in Example 1. 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 formable paper of the present invention is a multilayer paperboard mainly composed of wood pulp, thermoplastic synthetic fibers, and expandable microcapsule particles, and the wood pulp content is all. By producing a formable paper that is 51% by mass or more and the foamable microcapsule particles are 9 to 35% by mass with respect to the fiber layer as a layer, the density is relatively low, and the heat insulation and heat retention It was possible to provide a formable paper having characteristics such as cushioning properties and deep drawability. Moreover, by setting the blending ratio of wood pulp to 51% by mass or more, it is handled as paper by the Containers and Packaging Recycling Law.

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 0.156 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, the ratio of the thermoplastic synthetic fibers in the front and back layers was increased to 50%, and when the blending ratio of the wood pulp was less than 51%, it stuck to the mold at the time of thermoforming, it was difficult to come off, and the moldability was poor. Become.

  As described above, the formable paper of the present invention is mainly composed of wood pulp, thermoplastic synthetic fibers, and expandable microcapsule particles, so that when the deep drawing is formed, Can be deep-drawn without generation, has shape stability of the molded product, has heat insulation, heat retention, cushioning properties, etc. It has been found that by setting the content to 51% by mass or more, a bulky formed paper that can be handled as paper by the container packaging recycling method is obtained.

Claims (4)

Thermoformable foamable formable paper composed mainly of N-BKP (softwood bleached kraft pulp), thermoplastic synthetic fiber and foamable microcapsule particles, wherein the formable paper is a surface layer, at least one middle layer, It is a multi-layered paper with a wood pulp content of 51% or more composed of a back layer, and its diameter expands to about 4 to 5 times and its volume to 60 times or more by heating per 100% by mass of the fiber layer. The foamable microcapsule particles are blended in an amount of 10 to 40% by mass, and the foamable microcapsule particles are not blended in the surface layer and the back layer, or are blended in a maximum of 10% by mass less than the middle layer. A deep-drawn formable paper, characterized in that the dry microcapsule particles are dried without being foamed, then applied to a calendar and wound up to a thickness of 1 mm or less.   The foamable microcapsule particles are added to the front and back layers of the formable paper 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 paper. The deep-drawn formable paper according to claim 1, wherein the amount is 9 to 35% by mass.   The deep-drawn formable paper according to claim 1 or 2, wherein the thermoplastic synthetic fiber is a multi-branched polyethylene synthetic pulp having a melting point of 100 to 180 ° C.   The deep-drawn formable paper according to claim 1, 2 or 3, wherein the formable paper is heated and foamed by hot pressing at 100 to 220 ° C.