JPH0892898A - Low-density composite material - Google Patents

Abstract

PURPOSE: To obtain the subject composite material having new characteristic by imparting a processed layer capable of giving functional characteristics of value-added to one face of low-density paper obtained by impregnating a dispersion of expandable microcapsule into pulp for paper making and heat- foaming the dispersion. CONSTITUTION: This low-density composite material rich in new functional characteristics is obtained by providing a processed layer capable of imparting various functional characteristics to one face of a low-density paper which is obtained by impregnating an impregnating solution jointly using a dispersed solution containing expandable microcapsule in an amount of 2-30wt.%, based on pulp for paper making, and a rubber latex and/or synthetic resin emulsion in an amount of 15-40wt.%, based on the pulp, into paper made by using pulp for paper making as main raw material and having 50-60wt.% water content and 40-100b/m<2> weight before drying (in terms of absolute weight) by wet impregnation method, and heat-foaming the dispersing solution. Water resistance and solvent resistance can be imparted by attaching e.g. a synthetic resin film, and light resistance and light shielding property, etc., can be imparted or design property excellent in surface can be imported by using a metal plate, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-density composite material which is provided with a processing layer on the surface of low-density paper to impart new characteristics and can be suitably used for wall coverings and the like.

[0002]

2. Description of the Related Art Conventionally, low-density materials such as expanded polystyrene, expanded polyethylene, and expanded urethane have excellent heat insulating properties and heat retaining properties, and also have good moldability and are heat insulating materials and cushions because they are inexpensive. It has been widely used as a material and the like. However, these materials are inferior in natural degradability,
In addition, there are problems such as emission of pollutants and black smoke at the time of combustion, and in the actual situation, it is difficult to process the waste once it is discarded. Therefore, there is a strong demand for more environmentally friendly materials.

Against this background, some ideas have been proposed in which paper is applied as an environment-friendly material, the heat insulating property and the cushioning property are greatly improved at a low density, and the material is replaced with the above material. For example, JP-A-59-36800 proposes a method for producing low density paper by mixing polyester fibers.

Further, as a method for obtaining low-density paper by mixing hollow capsules into a paper, Japanese Patent Publication No. 52-39924 proposes a manufacturing method in which a shirasu balloon is internally added at the time of paper making.

On the other hand, expandable microcapsules which are foamed by heat are disclosed in US Pat. No. 2,797,201 and Japanese Examined Patent Publication No. 42-2.
As disclosed in JP-B-6524, JP-B-44-7344, etc., a blowing agent such as butane gas is included in a microcapsule such as a copolymer of methacrylic acid and styrene, a copolymer of acrylonitrile and styrene, and vinylidene chloride. The butane gas and the like expand by heating to form hollow resin spheres.

A method has also been proposed in which a paint or ink containing these expandable microcapsules is applied to paper, printed, stamped, and heated to foam to produce a low-density material. . For example, Japanese Patent Publication No. 53-31784
JP-A-54-31500, JP-A-62-2614
No. 36, Japanese Patent Laid-Open No. 3-241099, and the like propose the purpose of using it as a wallpaper material. Further, Japanese Patent Laid-Open No. 55-18116 proposes a method for producing low-density paper by internally adding expandable microcapsules to paper and heat-foaming. In addition, JP-A-5-33
No. 9898 has a moisture content of 65 to 72 before heat foaming.
A manufacturing method has been proposed in which a low-density paper is obtained by adjusting the content to be wt%.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The low-density paper proposed in No. 36800 has a limit in the effect of lowering the density, and it is difficult to obtain the effect unless a large amount of chemical fiber is incorporated into the paper, so the obtained paper is similar to synthetic fiber paper. The problem is that the original properties of paper and the environment-friendly properties are impaired.

In the method for producing low density paper proposed in Japanese Patent Publication No. 52-39924, the density difference between the shirasu balloon and the pulp for papermaking is large and the shirasu balloon floats on water, which makes it difficult to make paper. was there. Further, as can be seen from the examples of the publication, the density of the base paper produced is 0.37 to 0.67 g / cm3, and a low density comparable to that of expandable polystyrene (density about 0.1 g / cm3) is obtained. It is not possible.

Further, the above-mentioned Japanese Patent Publication No. 53-31784,
JP-A-54-31500, JP-A-62-261436
The proposals of JP-A-3-241099 and JP-A-3-241099 both use expandable microcapsules for the purpose of imparting air permeability and unevenness, and are not for reducing the density of the entire paper.

Further, the above-mentioned proposal of Japanese Patent Laid-Open No. 55-18116 is for the purpose of manufacturing a diaphragm, and the density of the obtained paper is lowered only by about 0.5 g / cm 3.

The low-density paper proposed in Japanese Patent Laid-Open No. 5-339898 mentioned above has a much larger water content in the wet paper before drying than the water content in the wet paper at the time of ordinary papermaking. Special consideration is required. In particular, since heat insulation is exhibited as the density of paper becomes low due to foaming, there is a problem that the drying efficiency is significantly reduced.

When the expandable microcapsules are internally added to paper to make paper and the foam is heated and foamed, the foaming method is very important. That is, as described above, the expandable microcapsules are microcapsules containing a liquid for foaming as a core substance, and it is necessary to heat the foamable microcapsules to an appropriate temperature for foaming. According to the observation results obtained by the inventors of the present invention using a fourdrinier paper machine, when the expandable microcapsules were mixed with paper-making pulp for papermaking and dehydrated and dried by an ordinary papermaking method, the foaming ratio was large and small. It was found that it was difficult to obtain a paper in a uniform foamed state due to the formation of parts and unevenness on the paper surface. It was confirmed that this non-uniform foaming state has already occurred at the very early stage of drying, which is the second to third lines on the inlet side of the dryer cylinder of the paper machine.

As a cause of this, the present inventors argue that the pulp fibers are dried in the end as a result of the contact with the heat source (dryer surface) being hindered and the foaming being delayed in the peripheral portion with respect to the previously foamed portion. It is presumed that this is because even if a strong inter-fiber bond is formed and foaming subsequently starts, the effect of expanding the pulp fibers to reduce the density of the paper no longer works. Furthermore, it is difficult to avoid formation unevenness (formation of fiber flocs) during the papermaking of paper, and as a result, there are many expandable microcapsules in the parts with a lot of pulp fibers, and conversely there is little pulp fibers. Since the presence of expandable microcapsules is reduced in the thin areas, it is estimated that the distribution of expandable microcapsules will be non-uniform and, in combination with the causes during the drying process described above, will result in non-uniform foaming. did.

On the other hand, in Japanese Unexamined Patent Publication No. 5-230798, a wet paper is made into paper by adding expandable microcapsules to a fiber material mainly composed of pulp (so-called internal addition method), and the wet paper is expanded into expandable microcapsules. It is disclosed that after drying at a temperature lower than the starting temperature, it is brought into contact with hot water of 90 ° C. or higher to foam microcapsules to produce a glutinous paper.

However, although this proposal has the effect of efficiently foaming the expandable microcapsules, the drying of the wet paper during the production of the base paper is controlled by a dryer of a general paper machine using pressurized steam as a heat source. It is difficult to carry out the treatment at 100 ° C. or lower, and it is necessary to immerse the paper once dried again in high temperature water and re-dry it, resulting in a problem that the drying energy efficiency of the paper is significantly deteriorated. Further, the method of internally adding the expandable microcapsules has another problem that the yield of expensive expandable microcapsules is low.
Further, in order to obtain good cushioning properties, it is not sufficient to foam the expandable microcapsules to obtain low-density paper. This is because the film thickness of the expandable microcapsules becomes thinner as the degree of foaming is increased and the density is lowered, and the paper becomes crushable even if the density is low.

The present inventors have studied to obtain a low-density paper using expandable microcapsules that solve these problems, and proposed it in Japanese Patent Application No. 6-58155. The gist of the present invention is that the basis weight of a paper made from papermaking pulp as a main material is 50 to 60% by weight and the basis weight before drying is 40 to 10%.
A paper sheet of 00 g / m 2 (converted to an absolute dry basis weight) was impregnated with an impregnating liquid mainly composed of expandable microcapsules by a wet impregnation method in an amount of 2 to 30% by weight with respect to pulp for papermaking, and then heated to form expandable microcapsules. The purpose is to expand the capsule to obtain low-density paper.

This low-density paper is lightweight, has excellent heat insulating properties, heat retaining properties, and cushioning properties, and is characterized in that it can be stably mass-produced. However, it has been pointed out that in order to develop various applications using this, performances such as designability, surface strength, feel, barrier property against liquid or gas, printability, etc. are insufficient depending on the use.
An object of the present invention is to obtain a low-density composite material that solves these problems.

[0018]

DISCLOSURE OF THE INVENTION According to the present invention, a paper having a water content of 50 to 60% by weight and a basis weight before drying of 40 to 1000 g / m 2 (converted to an absolutely dry basis weight) is produced by using papermaking pulp as a main material. 2 to 30% by weight of the impregnating liquid mainly consisting of expandable microcapsules is applied to the pulp for paper making by the wet impregnation method.
It is a low-density composite material characterized in that a processing layer is provided on at least one surface of a low-density paper produced by foaming expandable microcapsules by impregnation and then heating.

In the present invention, low density paper (hereinafter simply referred to as low density paper) is manufactured by utilizing the expandable microcapsules by the wet impregnation method. The papermaking pulp used in the present invention is not particularly limited, and any of those used in ordinary papermaking can be used. For example, unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBK)
P), hardwood bleached kraft pulp (LBKP), softwood bleached sulfite pulp (NBSP), etc. It is possible to use synthetic pulp or the like made from the above. In addition to the above pulp, acrylic fiber, rayon fiber,
It is also possible to use various fibers such as organic synthetic fibers such as polyester fibers and polyamide fibers, glass fibers, carbon fibers, alumina fibers, silica / alumina silicate fibers, inorganic fibers such as rock wool, and the like. For wood pulp, it is advantageous to use softwood pulp rather than hardwood pulp in terms of obtaining uniform impregnation.

The expandable microcapsules used in the present invention are obtained by encapsulating a low boiling point solvent in resin fine particles as described above, and have a diameter of 3 to 5 at a relatively low temperature of 70 to 150 ° C.
5 times to 3 times the average particle size that expands 30 to 120 times in volume
It is a particle of 0 μm. As the resin, usually vinylidene chloride, acrylonitrile, acrylic acid ester, a thermoplastic resin made of a copolymer such as methacrylic acid ester is used, as the low boiling point solvent is usually isobutane, pentane,
Use low-boiling solvents such as petroleum ether, hexane, low-boiling halogenated hydrocarbons. As the method for producing the expandable microcapsule, any conventionally known method can be used.

When the expandable microcapsules are heated above the softening point of the resin forming the outer shell, the resin begins to soften, and at the same time, the low boiling point solvent enclosed is vaporized and the vapor pressure rises. Are expanded and expanded to form closed cells. This makes it possible to obtain excellent heat insulating properties and cushioning properties. These expandable microcapsules include "Matsumoto Microsphere F-30D", "F-30GS", and "F-2" manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.
0D ”,“ F-50D ”,“ Expansel WU ”,“ Du ”sold by Nippon Philite Co., Ltd., etc., but the expandable microcapsules used in the present invention are not limited thereto. Not something.

The impregnating amount of the expandable microcapsules is 2 to 30% by weight, preferably 4 to 15% by weight based on the pulp for papermaking. If the amount is less than 2% by weight, a sufficiently low density cannot be obtained, and if the amount exceeds 30% by weight, the effect reaches the ceiling and is not suitable from the economical aspect, and further, the expandable microcapsules easily remain on the surface of the paper. Therefore, there is a drawback that the tendency of paper powder to fall off on the paper surface becomes strong.

In the present invention, auxiliary materials other than pulp are used as paper-making materials, for example, sizing agents, paper-strengthening agents, dyes, pigments, retention aids, fillers, pH adjusters, slime control agents, viscous agents, preservatives, and anti-preservative agents. Known materials such as mold agents and flame retardants can be used alone or in combination as necessary. In the case of the dry impregnation processing method, for example, when a sizing agent is added, the impregnation liquid is suppressed from permeating and impregnation processing becomes impossible. Further, the addition of a paper strengthening agent also works to reduce impregnating property and suppress foaming property, and its use is limited. However, in the case of the wet impregnation processing method, since the impregnation is performed before the effects of these additive chemicals are exhibited, there is an advantage that there is no particular restriction.

Next, a method of manufacturing the low density paper used in the present invention will be described. FIG. 1 shows that the present inventors have filed Japanese Patent Application No. 6-58.
It is an example of the dry impregnation processing apparatus used for the explanation in No. 155, and its conceptual diagram is shown. The wet paper web 2 supplied from the wire part 1 is impregnated with the impregnating liquid 3 by an impregnating vat, guided by a wire 4 to a cylinder dryer 5, and dried. Specifically, a wet paper 2 is prepared by forming a web using a paper making machine such as a Fourdrinier, a cylinder, and a shortdrind with pulp for papermaking as a main material, and dehydrating the water content to 50 to 60% by weight by a press part or the like. Put it on wire 4,
Immerse in the impregnating liquid 3 containing expandable microcapsules, then squeeze, and then pass through the cylinder dryer 5,
By drying the expandable microcapsules while foaming, a low-density paper having a large number of closed cells in which the expandable microcapsules are expanded in the paper layer can be obtained.

In the present invention, in addition to the expandable microcapsules, the impregnating liquid contains rubber latex such as natural rubber latex, styrene / butadiene copolymer latex, methylmethacrylate / butadiene copolymer latex and / or polyacrylic ester emulsion. , A binder of synthetic resin emulsion such as polyvinyl acetate emulsion and polyvinyl chloride emulsion can be used together.
The impregnation ratio of these is 5 to 40% by weight, preferably 10 to 25% by weight, based on the pulp for papermaking. By doing so, the distribution of the expandable microcapsules becomes more evenly dispersed. Furthermore, the pulp fibers and the expandable microcapsules can be prevented from falling off, and the strength can be improved. Also, by selecting the addition rate together with the type of binder, it is possible to freely design paper according to the purpose, such as making the paper quality harder or softer, so it is possible to prevent paper powder from falling off and to reduce the density. The use of the low-density paper of the present invention can be expanded by making it a flexible, durable material.
If the impregnation ratio is less than 5% by weight, it becomes difficult to obtain these effects, and if it exceeds 30% by weight, it becomes economically disadvantageous and it is difficult to expect further effects.

Further, by blending various materials in addition to the above-mentioned binder, a characteristic application can be developed. For example, a low-density paper having antifungal properties can be obtained by adding a fungicide, and a flame-retardant low-density paper can be obtained by adding a flame retardant.

The present invention imparts various functions by providing a processing layer on at least one surface of the low-density paper thus produced. This will be specifically described below.

1. Lamination of sheet material The present inventors considered the following as an added value to low density paper. That is, imparting barrier properties (water resistance, solvent resistance, oxygen permeability, light resistance, light shielding properties, soundproofing properties,
This is a study aimed at improving heat insulation, impact resistance, mold resistance, antibacterial properties, dew resistance, insect resistance, etc.) and surface design (printability, color tone, touch, texture, etc.). . Various sheet-like materials suitable for the above-mentioned barrier properties and surface design properties are generally widely used. INDUSTRIAL APPLICABILITY The present invention can provide a composite material having the characteristics of these sheet-like materials and the characteristics of low-density paper.

For example, when a synthetic resin film or sheet is laminated, a barrier property such as water resistance and solvent resistance is added, the color tone can be freely changed, and further matting or patterning treatment is performed. By doing so, many characteristics can be obtained. Further, by laminating or sandwiching with a metal plate, a metal foil or a sheet, properties such as light resistance, light shielding property, gas barrier property can be added. Furthermore, by shielding both surfaces of the low-density paper, which is a porous material, with these materials, the air layer inside becomes airtight, and properties such as heat insulation and soundproofing can be added.

As a laminating method, there are a wet lamination method, a dry lamination method, a hot melt lamination method, an extrusion lamination method, a thermal lamination method, a pressure sensitive adhesive sheet method and the like. When the nip pressure is strongly applied by the pressure roll, the low-density paper moves in the direction in which the low-density paper is crushed and the density increases, so care must be taken in heating the nip pressure and the pressure roll. The soft press-bonding method by the belt press method does not have this effect.

Specific materials used for bonding include:
Various materials can be selected according to the purpose. For example, as a water resistant and water vapor permeable barrier, plastic films and sheets such as polyethylene, polypropylene, polyvinylidene chloride, polyester, polycarbonate, polyvinyl alcohol with a high degree of saponification, polyamide, aluminum, stainless steel, galvanized sheet, tin plate A metal plate such as copper or a metal foil or sheet can be applied. Regarding the solvent resistance, it is possible to use a material depending on the solvent used, and various plastic films or sheets, metal foils or sheets, etc. as described above can be applied according to the purpose. Furthermore, light resistance and light-shielding properties can be added by bonding with a metal foil or sheet, a metal vapor deposition film, or the like. When pasted with various types of paper, such as high-quality paper, printing paper, coated paper, paperboard, fancy paper, cardboard, synthetic paper, etc., the aesthetics, texture, texture, shock-absorbing properties, and heat insulation are accompanied by the properties of each material. And properties such as soundproofing are added. Similarly, various fabrics (natural fibers such as cotton, wool, silk, vinylon, tetron, nylon,
Synthetic fibers such as polyester, semi-synthetic fibers such as acetate rayon, glass fibers, carbon fibers, inorganic fibers such as ceramic fibers), non-woven fabrics, split cloths, or natural leather, fur or synthetic leather. Properties such as aesthetics, touch, texture, heat insulation, flame retardancy, and soundproofing are added together with the properties of the material.

Furthermore, by adhering the sponge sheet to the sponge sheet, it is possible to add the soft cushioning property of the sponge to the lightweight property and the firm cushioning property of the low-density paper, and two different elastic materials can be obtained. Further, the free deformability of the sponge makes it possible to apply it to a material having a large variation in surface irregularity. Also, a material with excellent heat insulation and soundproofing is prepared by laminating a film or sheet (plastic film, plastic sheet, metal foil, etc.) with low air permeability on at least one side of low-density paper, and combining this with a sponge. Can be provided.

When a sheet of thin natural wood is laminated,
It is a material that makes the best use of the texture and feel of natural wood. in this case,
It becomes a material that is lightweight and has a thick feeling, and it can also exhibit dew-proof performance as a property of natural wood on the surface.

In the wet lamination method, a water-based adhesive is applied to one of the base materials, and before the adhesive is dried,
This is a method in which it is immediately laminated to another one of the substrates and dried, and is a laminating method suitable for a porous material such as the low-density paper that allows easy transmission of water vapor. As an adhesive,
Water-soluble proteins include glue, casein, gelatin, etc., carbon-containing adhesives such as starch, dextrin, cellulose derivatives (carboxymethylcellulose, methylcellulose, ethylcellulose, etc.), sodium alginate, etc., inorganic adhesives such as sodium silicate. There is. Further, as a synthetic resin emulsion, a vinyl acetate emulsion, an acrylic ester emulsion, or a copolymer modified resin by grafting thereof, such as an acrylic modified vinyl acetate emulsion, an ethylene vinyl acetate copolymer (EVA) emulsion, styrene, an acrylic ester copolymer is used. There are polymer emulsions and the like.

As the wet laminator, general equipment such as a roll coater, a reverse roll coater, a gravure roll coater, an air knife coater and a Mayer bar coater can be used. In the case of the wet lamination method, the drying temperature is generally lower than that of the dry lamination method, but as described above, since the low density paper is composed of the fine foamed spheres of the thermoplastic resin, the drying temperature is 80 ° C.
Hereafter, it is desirable to carry out at 60 ° C. or lower.

In the dry lamination method, various substrates are uniformly coated with an adhesive dissolved in water or a solvent by a gravure coater, a dip coater, a kiss roll coater, a squeeze roll coater, a reverse roll coater, an air knife coater, etc. This is a method in which a solvent is evaporated in a drying oven and a base material to be bonded is overlaid on the adhesive surface which has become a dry adhesive state, followed by pressure bonding and laminating. This method has a wide range of application of materials to be laminated, and it is possible to add features such as heat resistance, cold resistance, gas barrier property, and chemical resistance by selecting the type of adhesive and the coating amount. As the adhesive, there are an aqueous type and a solvent type. Solvent-based adhesives include vinyl-based, acrylic-based, epoxy-based, rubber-based, and urethane-based adhesives, which can be selected according to the application. In addition, the material used for bonding is
Various materials as described above can be selected according to the purpose.

In the dry lamination method, since heating and pressure bonding are performed by a heated metal roll and a rubber roll, there is a problem in controlling the temperature of the metal roll and the nip pressure when applying pressure. The low-density paper tends to be deformed by heat and pressure as described above, and the temperature of the metal roll is 8
It is important that the temperature is 0 ° C. or lower, preferably 60 ° C. or lower, and the nip pressure is not increased more than necessary in consideration of the density of the material to be used after bonding.

The pressure-sensitive adhesive sheet method is a method in which various double-sided pressure-sensitive adhesive tapes or materials that have been subjected to pressure-sensitive adhesive processing are used for bonding. With this method, there is no adhesive drying step, and it can be said that this method is the method with the smallest change in density for bonding low-density paper to which expandable microcapsules are applied. As the material used, any of the materials described above can be used.

2. Providing a coating layer The present inventors then considered providing a coating layer as an added value to low density paper. That is, this is a study for the purpose of improving barrier properties (water resistance, solvent resistance, oxygen permeability, light resistance, light shielding properties, etc.) and surface design properties (printability, color tone, touch, texture, etc.). Various coating methods suitable for the above-mentioned barrier properties and surface design properties are generally widely used. The present invention can provide a composite material having the characteristics of these coating layers and the characteristics of low density paper.

The coating layer can be obtained by applying a water-based paint, a solvent-based paint, a melt extrusion coating of a thermoplastic resin, or the like on the surface of low-density paper. For example, a composite material having excellent printability can be produced by preparing a water-based paint mainly containing various inorganic powders and a binder and applying the paint on the surface of lightweight paper. Further, a vinyl chloride paste mainly composed of a vinyl chloride resin and a plasticizer is applied and heat-treated to produce a composite material having the surface coated with the vinyl chloride resin. It can be suitably used for building materials. Moreover, by molding a composite material obtained by melt extrusion coating polyethylene or polypropylene on the surface of low density paper using an extruder, it is possible to manufacture a lightweight food container that is easily incinerated.

3. Emboss processing. The inventors then considered embossing as an added value to low density paper. The purpose of embossing is to improve the surface design (touch feeling, texture, etc.). The embossing treatment may be applied to the low density paper itself, or may be applied to the low density paper to which the above-mentioned sheet-like material is attached or the low density paper provided with a coating layer. A conventionally known method can be used for the embossing method. For example, low-density paper or the above-mentioned composite material is passed between an embossing roll made of metal having an uneven pattern on its surface and a counter roll made of metal or hard rubber for processing. At this time, heating the embossing roll is also appropriately performed. A preferred application example will be described. By coating PVC resin on the surface of low density paper and embossing it, a very lightweight synthetic leather-like composite material can be obtained.
This composite material can be suitably used as an interior material for buildings and an interior material for automobiles.

[0042]

【Example】

Example 1 Production of Low Density Paper 100 parts by weight of softwood bleached sulfite pulp (NBSP) (dry weight conversion, the same applies hereinafter) was disintegrated and a sizing agent (trade name "Size Pine K-902", manufactured by Arakawa Chemical Co., Ltd.) 0.5 parts by weight was added to make a stock with a concentration of 0.5% by weight. Using this paper material, a Fourdrinier paper machine having a wet impregnation processing device as shown in FIG. 1 has a wet paper basis weight of 2 before impregnation.
Paper is made so that it becomes 00 g / m 2 (converted to dry weight), and then as an impregnating liquid, expandable microcapsules (trade name “Matsumoto Microsphere F-30D”, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd., particle size 10 to 20 μm, cell Softening temperature 8
Styrene / butadiene copolymer latex (trade name "Luck Star", manufactured by Dainippon Ink and Chemicals, Inc.) was dispersed in water to 6% by weight (0 ° C) to prepare an impregnating solution. Wet paper is dipped and then impregnated by adjusting the squeezing condition so that the impregnation rate becomes about 20% by weight (dry weight conversion). 10 front dryer cylinders (surface temperature, 110 ° C.), rear dryer cylinder 10 A low-density paper having a basis weight of 240 g / m 2, a thickness of 1.47 mm, and a density of 0.16 g / cm 3 was obtained by drying with a multi-cylinder dryer part consisting of a book (surface temperature, 125 ° C.). Lamination with sheet-like material Using this low-density paper, a polyurethane adhesive (trade name "Takenate A-975" and "Takenate A-3",
Takeda Pharmaceutical Co., Ltd.) 5g with gravure coater
/ M2 (dry weight conversion) coated polyester film (trade name "Ester film E-5100", thickness 2
5 μm, manufactured by Toyobo Co., Ltd.) by a dry lamination method to manufacture a low density composite material. It had excellent performance as a lightweight food tray.

Example 2 The low-density paper used in Example 1 was melt-extruded and coated with polyethylene having a thickness of 15 μm at 360 ° C. using an extruder to produce a low-density composite material. It had excellent performance as a lightweight food cup.

Example 3 100 parts by weight of polyvinyl chloride paste resin, 80 parts by weight of plasticizer (dioctyl phthalate), 30 parts by weight of titanium dioxide, 50 parts by weight of calcium carbonate, foaming agent were added to the low density paper used in Example 1. 15 parts by weight, 3 parts by weight of stabilizer,
Apply a paint consisting of 15 parts by weight of black-brown coloring pigment, and
A low density composite material was manufactured by heating at 0 ° C. for 1 minute. This had excellent performance as a material for a book cover.

Example 4 Using the low-density composite material of Example 3, a vinyl chloride resin coated surface was heated to 80 ° C. while a metal embossing roll having a textured pattern and a hard rubber counter were used. An embossed low density composite material was produced by passing between the rolls. It had excellent performance as a building interior material.

[0046]

The low-density paper of the present invention, which is obtained by uniformly impregnating the expandable microcapsules into the paper layer by the wet impregnation processing method to foam, is obtained by the conventional method using expandable microcapsules. Foaming that is much more uniform than that of the low-density paper is obtained, and the surface properties are excellent and the density can be reduced. It is possible to add various performances to the low-density paper by laminating various sheet-like substances to this low-density paper, applying various coating liquids, and embossing these. Became. Taking advantage of these characteristics, the low-density composite material of the present invention is a printing sheet, a wall covering material, a building material such as a ceiling material, an automobile interior material, a curing sheet, various packaging materials, a cushioning material, a box outer packaging material, and a stationery. It can be preferably used for books, book covers, mailing bags, insole materials, bag core materials, various catalogs, coasters, menus and the like.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an example of a wet impregnation processing device.

[Explanation of symbols] 1 wire part 2 wet paper 3 impregnating liquid 4 wire 5 cylinder dryer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 33/00 9349-4F D21H 17/31 (72) Inventor Yoko Watanabe Nagaizumi-cho, Sunto-gun, Shizuoka Honjuku 501 Special Paper Manufacturing Co., Ltd.

Claims (5)

[Claims] 1. A grammage of 50 to 60% by weight of water, which is made from papermaking pulp as a main material, and has a basis weight of 40 to 1000 g before drying.
2 to 30% by weight of the pulp for paper making is impregnated with an impregnating liquid mainly composed of expandable microcapsules into a paper sheet of / m2 (converted to an absolute dry basis weight) and then heated to form expandable microcapsules. A low-density composite material, characterized in that a processed layer is provided on at least one surface of a low-density paper produced by foaming. 2. The low-density composite material according to claim 1, wherein the impregnating liquid contains expandable microcapsules together with rubber latex and / or synthetic resin emulsion in an amount of 5 to 40% by weight based on the pulp for papermaking. 3. The low-density composite material according to claim 1 or 2, wherein the processed layer is a sheet-like material laminated. 4. The low-density composite material according to claim 1, wherein the processing layer is a coating layer. 5. The low-density composite material according to claim 1, wherein the surface is embossed.