JP2003175570A - Method for manufacturing moistureproof paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose an inexpensive and convenient method for manufacturing a moistureproof paper when the moistureproof paper with a constitution of a paper/a moistureproof layer/a paper and with excellent biodegradability and moldability is manufactured. <P>SOLUTION: The method for manufacturing the moistureproof paper consisting of the paper/the moistureproof layer/the paper and with a moisture permeability measured at 40°C and 90%RH of at most 100 g/(m<SP>2</SP>.24 hr) is provided, and the method for manufacturing the moistureproof paper is characterized by the moistureproof layer comprising a biodegradable resin composition and basis weight of the moistureproof layer being 10-40 g/m<SP>2</SP>and the moistureproof paper being formed by laminating two papers with a melted biodegradable resin composition. It is preferable that the lamination is performed under a nitrogen gas atmosphere. <P>COPYRIGHT: (C)2003,JPO

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 a composite paper of paper and resin, which is used for a paper container such as a detergent box which is required to have moisture resistance. In particular, it relates to an inexpensive and simple method for producing a biodegradable composite paper having high moisture resistance.

[0002]

2. Description of the Related Art Conventionally, as a paper container for powder detergent, a paper support on which a synthetic resin such as polyethylene or polypropylene is laminated is used. Since these poly-laminated papers have a strong coating layer, when the used paper is collected and reused, the coating itself remains on a large sheet, and when fragmented pieces are mixed in the paper making process, they are fused to a cylinder dryer. There's a problem. Further, when it is landfilled, there is a problem that the synthetic resin is not decomposed in the natural world, and in most cases, such poly-laminated paper is incinerated at present.

Moisture-proof paper obtained by laminating paper by hot-melt method has also been used as a detergent box for a long time, but it also has the same problems as described above.

Under these circumstances, many techniques have been disclosed in which the moisture-proof layer is made of a releasable resin and is used as waste paper. For example, Japanese Patent Application Laid-Open No. 10-27 by the present applicant
A representative example is Japanese Patent No. 8189.

However, small paper containers and the like are actually difficult to put on the used paper collection route, and it is rather preferable that they can be composted with raw garbage or can be landfilled and returned to the natural world. As an example of using a biodegradable resin as a resin laminated with paper, for example, Japanese Patent No. 310
8201, JP 2000-289750, and the like.

By the way, it is composed of paper / moisture-proof layer / paper,
The composite paper in which the moisture-proof layer is formed by hot melt has an advantage that the production is inexpensive and simple. Further, it is convenient to use by water-resistant processing, oil-resistant processing, heat-sealing processing, etc. on one surface and printing on the other surface. Furthermore, when molding / boxing as a container, the processability is good because the middle layer is soft, and because the surface is paper,
There are many advantages such as good slipperiness during molding and strong adhesion with an aqueous adhesive such as starch or polyvinyl alcohol.

It is considered that a biodegradable hot melt resin should be used in order to make a biodegradable container while taking advantage of the above advantages. Biodegradable hot melt adhesives are disclosed in JP-A-5-339557, JP-A-7-278510, and JP-A-10-251612.

JP-A-5-339557 discloses that polylactic acid or lactic acid and another hydroxycarboxylic acid copolymer are contained and the melt viscosity is 10 cp to 30,000 c at 180 ° C. to 210 ° C.
A Homolt adhesive of p is disclosed. It is described that it is particularly suitable for adhesion of biodegradable plastics, such as paper, cloth,
It is described that it can also be used for bonding non-woven fabric, glass, aluminum and the like.

Japanese Unexamined Patent Publication (Kokai) No. 7-278510 discloses a biodegradable hot melt adhesive composed of natural rubber, raw rosin and wax.
Examples include packaging, bookbinding, plywood, and the like.

In Japanese Patent Laid-Open No. 10-251612, a hot melt adhesive containing a thermoplastic resin and a tackifier as main components is used, and as the thermoplastic resin, an aliphatic dicarboxylic acid (anhydride or ester), an alkyl group or an alkenyl group is used. A hot melt adhesive using an aliphatic dicarboxylic acid (anhydride or ester) having a group and an aliphatic polyester reacted with an aliphatic glycol is disclosed. It is described that it is suitable for adhering paper, biodegradable resin, etc., as well as adhesives for assembling packaging packages, food packaging containers, and the like.

[0011]

DISCLOSURE OF THE INVENTION The present invention proposes an inexpensive and simple production method for producing a moisture-proof paper having a constitution of "paper / moisture-proof layer / paper" excellent in biodegradability and moldability. Is an issue.

[0012]

In order to solve the above problems, the present invention adopts the following configurations. That is, the first aspect of the present invention is "a paper / moisture-proof layer / paper, according to JIS Z-020.
A method for producing a moisture-proof paper having a water vapor permeability measured at 40 ° C. and 90% RH of 100 g / (m ² · 24 hours) or less in accordance with the method specified in 8, wherein the moisture-proof layer is a biodegradable resin composition. The moisture-proof layer has a basis weight of 10 to 40 g / m ² , and the moisture-proof paper is formed by a method in which two sheets of paper are laminated with a molten biodegradable resin composition. A method for producing a moisture-proof paper, which is characterized. It is.

A second aspect of the present invention is the same as the first aspect.
The pasting is performed in a nitrogen gas atmosphere, which is a method for producing a moisture-proof paper.

A third aspect of the present invention is the first or second aspect of the invention.
In the invention, the laminating is performed by applying the biodegradable resin composition melted by a hot melt coater to one of the papers, and feeding the other paper onto the paper. Is the way.

In a fourth aspect of the present invention, in any one of the first to third aspects of the invention, the laminating is performed by a die coater, and the die has a gear roll, and a coating amount is obtained by rotating the gear roll. Is a method for producing a moisture-proof paper.

A fifth aspect of the present invention is the method for producing a moisture-proof paper according to any one of the first to fourth aspects, wherein the biodegradable resin composition contains natural rubber as a main component. is there.

A sixth aspect of the present invention is based on the fifth aspect of the invention.
The biodegradable resin composition is a method for producing a moisture-proof paper further containing a vegetable protein or a polysaccharide.

A seventh aspect of the present invention is the biodegradable resin composition according to any one of the first to sixth aspects, wherein the biodegradable resin composition is JIS K-6.
When the melt viscosity specified in 862 is 150 ° C.,
The method for producing a moisture-proof paper is characterized in that it is 1 to 1000 Pa · S.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION As the paper used in the present invention, paper, paperboard, cardboard base paper and the like which have been conventionally used for various packaging papers can be used. There is no particular limitation on the tsubo of the paper, but for each of the two papers, 3
About 0 to 600 g / m ² is preferable. More preferably, each is 50 to 300 g / m ² , and the total is 100 to 600 g / m ² .

The paper used in the present invention contains natural pulp fibers as a main component, and as the natural pulp,
Wood fibers (chemical pulp, mechanical pulp), non-wood fibers, waste paper pulp and the like are optionally used. Among the wood fibers, the chemical pulp includes kraft pulp that uses caustic soda and sodium sulfide during wood chip cooking,
Examples include sulfite pulp that uses sulfurous acid and hydrogen sulfite. These pulps may be unbleached or bleached. As mechanical pulp, ground wood pulp (GP) obtained by grinding logs with a grinder, refiner ground wood pulp (RGP) obtained by grinding (refining) waste wood from a sawmill, and wood. Thermo-mechanical pulp (TM) obtained by heating and refining chips
P) and the like. As the used paper pulp, undeinked used paper pulp, deinked used paper pulp, super-white used paper pulp, corrugated used paper pulp and the like can be used.

These pulp fibers may be used alone or in two
It is possible to use more than one kind in combination. If necessary, biodegradable resin fibers can be mixed within the range that does not impair the effects of the present invention. Examples of biodegradable resins that can be used include aliphatic polyester, biodegradable cellulose acetate, polylactic acid, and polycaprolactone.

When making the paper used in the present invention, a filler and a paper-making chemical may be added if necessary. Examples of papermaking chemicals include sizing agents, paper strength agents, and yield improving agents used in ordinary papermaking. Examples of the sizing agent include alkyl ketene dimer, styrene acrylic resin, rosin, and other internally added sizing agents. As a paper strength agent and a yield improver, polyacrylamide resin, polyamide epichlorohydrin resin, polyethyleneimine and its derivatives, polyethylene oxide, polyamine, polyamide, polyamide polyamine and its derivatives, cationic and amphoteric starch, oxidized starch, carboxymethylated starch , An organic compound such as vegetable gum and polyvinyl alcohol, and an inorganic compound such as a sulfuric acid band, alumina sol, colloidal silica, and bentonite are appropriately combined and used.

As the filler, mineral substances such as talc, kaolin, calcined kaolin, clay, diatomaceous earth, ground calcium carbonate, magnesium carbonate, aluminum hydroxide, titanium dioxide, magnesium sulfate, silica, aluminosilicate, bentonite, etc. An organic synthetic filler such as or polystyrene particles or urea formalin resin particles may be appropriately selected and used in combination. Further, a papermaking additive such as a dye, a pH adjusting agent, a slime control agent, an antifoaming agent, and a sticky agent can be appropriately used depending on the application.

The papermaking machine may be any of ordinary fourdrinier paper machine, cylinder paper machine, shortnet paper machine, inclined paper machine, various combination paper machines, etc., and is not particularly limited. The drying may be any of a normal multi-cylinder dryer, a Yankee dryer, a through dryer, etc., and is not particularly limited. Further, in the present invention, the paper support obtained from the paper making step may be not only a single layer but also a laminated paper having two or more layers.

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 biodegradable resin composition of the present invention is basically composed of a base polymer and a tackifier as in the case of ordinary hot melt adhesives, and optionally contains a viscosity reducing agent such as wax. To do. The base polymer is a polymer compound that is necessary for maintaining the strength of the moisture-proof layer as a structure and has an appropriate cohesive force, and is a biodegradable resin in the present invention. However, in order to enable hot melt coating, the base polymer itself also needs to be easily softened by heat, and also because the moisture-proof layer is not cracked by the molding process and the moisture-proof property is not lowered, A low softening point is required.

Examples of such a biodegradable base polymer include polylactic acid or a copolymer of lactic acid and hydroxycarboxylic acid described in JP-A-5-339557. In addition, natural rubber described in JP-A-7-278510 can be mentioned. Furthermore, JP-A-1
The aliphatic polyester which has a side chain as described in 0-251612 is mentioned.

As the aliphatic polyester having a side chain, an aliphatic dicarboxylic acid (anhydride or ester), an aliphatic dicarboxylic acid having an alkyl group or an alkenyl group (anhydride or ester), and an aliphatic glycol are reacted. Aliphatic polyesters may be mentioned. In the above, examples of the aliphatic dicarboxylic acid and the like include succinic acid or its anhydride or its diester, and as the aliphatic dicarboxylic acid having an alkyl group or an alkenyl group, alkylsuccinic acid or alkenylsuccinic acid,
Alternatively, their anhydrides or diesters may be mentioned. Examples of the aliphatic glycol include 1,2-ethylene glycol, 1,4-butanediol and 1,6-hexanediol. As a specific example, succinic acid 60
And a polyester having an average molecular weight of about 50,000 obtained by polycondensing 40 mol of octenylsuccinic acid and 1,4-butanediol.

The polylactic acid or the copolymer of lactic acid and hydroxycarboxylic acid is preferably a polymer having a molecular weight of 20,000 to 500,000. As the hydroxycarboxylic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid or the like can be used.

Natural rubber is present as rubber particles in a latex obtained from a rubber tree and has a rubber content of 30 to 40.
It is said that the weight% and the particle size are large and are 0.1 to 0.5 μm. The main component of the rubber particles in the latex is cis-1,4-polyisoprene, and the average degree of polymerization is about 5,000, but it is said that the surface of the rubber particles is covered with a phospholipid and protein layer. There is. The natural rubber used as the base polymer of the present invention is obtained by concentrating the latex to a rubber content of about 60% by weight and adding ammonia or the like as a preservative, or separating the rubber particles in the natural rubber latex by coagulating. It is possible to use dried so-called raw rubber.

The tackifier will be described. The tackifier is also called a tackifier, and it is preferable to use it to enhance hot tackiness during hot melt coating,
At the same time, it also dissolves with the base polymer and acts to reduce the melt viscosity of the entire mixture. In the present invention, when used, it is necessary to use a biodegradable tackifier. As an example, in the Japanese Patent Application No. 2000-100699 of the present applicant, rosin, terpene, rosin ester, shellac, which is proposed as a plasticizer for natural rubber-based biodegradable resin,
Polyalkylene alkanoate polyol, low molecular weight polycaprolactone diol, low molecular weight polycaprolactone triol and the like can be used. Other than that, terpene-phenol resin, low molecular weight polylactic acid, etc. can also be used.

The viscosity reducing agent may be added, if necessary, in order to improve the fluidity of the biodegradable resin composition during hot melt coating. As the viscosity reducing agent, what is generally called a wax can be used, but in the present invention, it is necessary that it is biodegradable, and various plant-based or mineral-based natural waxes can be used. For example, carnauba wax, castor wax, rice wax, paraffin wax, montan wax, microcrystalline wax and the like can be used. In addition, low molecular weight aliphatic polyester, fats and oils such as soybean oil, and low molecular weight polyether can be used. These viscosity reducing agents also contribute to the improvement of moisture resistance.

In the present invention, a biodegradable auxiliary agent such as a natural polysaccharide or protein may be added in order to assist the biodegradability of the base pomer. Examples of the protein include vegetable proteins such as corn gluten and soybean protein, which the applicant of the present invention proposed in Japanese Patent Application No. 2000-100699 to prepare a biodegradable resin composition by mixing with natural rubber. Starch is mentioned as a polysaccharide.

The mixing ratio of each of the above-mentioned components differs depending on the material and cannot be generally stated, but 20 parts of the tackifier is added to 100 parts by mass of the total of the base polymer and the biodegradable auxiliary.
˜500 parts by mass is preferred. Further, it is preferable to add 5 to 50 parts by mass of the viscosity reducing agent to 100 parts by mass of the total of the base polymer, the biodegradable auxiliary and the tackifier. In any case, the biodegradable resin composition for forming the moisture-proof layer has a Brookfield type single-cylinder rotational viscometer of 15 according to the measuring method specified in JIS K-6862.
It is preferable to adjust to a range of 0.1 to 1000 Pa · S when measured at 0 ° C. If the viscosity is lower than this range, it may penetrate into the paper excessively to lower the moisture resistance, or stains may be visible on the paper surface. If it is higher than this, it becomes difficult to form a coating film having a uniform thickness. For the same reason, a more preferable range is 1 to 100 Pa · S.

In the present invention, the merit of setting an appropriate viscosity range is related not only to the above-mentioned points but also to moisture resistance.
Generally, the moisture resistance of the composite paper is considered to depend on the thickness of the resin film, but when the voids of the cellulose fiber are sufficiently filled with the resin, the moisture resistance of the crystal itself of the cellulose fiber is also exerted, and The superior moistureproof property estimated from the moistureproof layer is obtained. Therefore, the viscosity may be selected so that the vicinity of the surface layer of the paper is sufficiently impregnated with the hot melt resin composition.

Further, particles such as pigments or fine fibers may be added to the biodegradable resin composition having the above-mentioned composition. Addition of them improves moisture resistance or heat resistance of laminated paper. When the particles or fine fibers are organic resins, they need to be biodegradable resins. Examples of biodegradable resins include polycaprolactone-based resins, biodegradable cellulose ester resins, polyalkylalkanoate-based resins, polylactic acid-based resins, starch-based resins, polyvinyl alcohol-based resins, and the like. Further, polymers or copolymers of 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid and the like can be mentioned. As the biodegradable cellulose ester, it is desirable to use cellulose acetate having an acetylation degree of 30 to 56%, which is disclosed in Japanese Patent Application Laid-Open No. 2000-341092 by the present applicant.

Examples of the inorganic particles include calcium carbonate, clay, kaolin, silica, aluminum hydroxide, zinc oxide and titanium oxide. Further, in order to further improve the moisture resistance, a tabular pigment is preferable. The tabular pigment preferably has an aspect ratio of 4 or more, and particularly preferably 6 or more. The aspect ratio mentioned here is a value obtained by dividing the average particle diameter by the laser diffraction method by the average plate thickness of the tabular grains. The particle size measurement by the laser diffraction method is made by Shimadzu Corporation "Laser diffraction method particle size distribution measuring device SALD-200.
It can be measured by "0J". As such a tabular pigment, kaolin, talc, mica, sericite, aluminum hydroxide and the like are desirable.

Next, the coating method will be described. The method of the present invention is characterized in that two sheets of paper are laminated with a melted biodegradable resin composition.

As a method of forming a moisture-proof film between papers, generally known is a method of sticking a moisture-proof film to a paper using an adhesive. However, in this method, a film formed in advance is prepared, and further two adhesive layers are required, so that the operation is complicated. Further, when a high temperature is applied during drying, the film shrinks, the paper curls, etc., so it is actually difficult to apply a temperature of 100 ° C. or higher to the film layer, and the sheet cannot be sufficiently heat-sterilized. Therefore, there is a risk that microorganisms adhere to the moisture-proof layer. As another method, there is a method of sticking papers together with an aqueous dispersion of a biodegradable resin, but this method also has the same drawbacks as described above.

In the present invention, the temperature of the molten biodegradable resin composition supplied to the paper is preferably in the range of 120 ° C to 300 ° C, more preferably about 140 ° C to 220 ° C, so-called hot melt coating. Area. According to the method of the present invention, the biodegradable resin is melted and applied at a high temperature of, for example, 140 ° C. or higher, so that the resin is completely sterilized at that time, and microorganisms that decompose the resin are attached. Never. Therefore, the moisture-proof paper produced by the method of the present invention can be stored for a long time if sealed.

In the present invention, the apparatus for supplying the molten resin to the paper may be either a roll coater or a die coater. In a die coater, a molten resin film may be supplied between two sheets of paper and pressure-bonded, or a molten resin film may be formed on one sheet of paper and another sheet of paper may be pressure-bonded onto it. It is also possible. With a roll coater, it is rational to form a molten resin film on one sheet of paper and press another sheet of paper on it.

In the die coater, a general method of supplying the molten resin to the die head with a pump or a screw may be adopted. However, it is preferable to reduce the thickness unevenness as much as possible in order to sufficiently exhibit the moisture-proof property with a small amount of coating of an expensive biodegradable resin. A thin, uniform coating also has faster biodegradability. Therefore, the most recommended coater in the method of the present invention is a method having a gear roll in the die and controlling the coating amount by the rotation speed of the gear roll. An example of such a device is the GPD (Gear Pump Die) system of Yuri Roll Machine Co., Ltd.

The biodegradable resin has a risk of being oxidized or decomposed in the presence of water, and in any of the apparatuses, the molten resin contains oxygen and oxygen during melting, transportation to a die, and coating completion. It is preferable to eliminate water vapor as much as possible and create an atmosphere in which nitrogen gas is replaced. In addition, it is preferable to provide a step of defoaming while applying a back pressure in a step of supplying the molten resin to the die head, for example, with a device such as a vent type screw extruder. This is because moisture resistance is impaired if air bubbles remain in the molten resin. According to the above-mentioned GPD system, the above-mentioned nitrogen gas replacement and defoaming can be performed. Therefore, it is preferable to use the GPD system also in this respect. In addition, when the above system is used, it is possible to apply a material having a viscosity higher than that of a normal applicator roll method, and therefore it is possible to apply only the base polymer.

Moisture proof property suitable for packaging dry powder such as detergent is 100 g / (m ² at 40 ° C. and 90% RH in accordance with the method defined in JIS Z-0208.
・ 24 hours or less) More preferably 10
It is ~ 60 g / (m ² · 24 hours). In order to realize such moisture resistance with a small coating amount, each of the formulations of the present invention described above is effective, and according to the GPD system, it is realized in the range of 10 to 40 g / m ² of rice grammage of the moisture-proof layer. It will be possible.

[0045]

[Examples] <Example 1> 100 parts by mass of natural rubber (smoked sheet grade) and 80 parts of raw rosin per 100 parts by mass of corn gluten meal (manufactured by Oji Corn Starch)
A uniform biodegradable resin composition was obtained by mixing 15 parts by mass with a kneader mixer (Labo Plastomill manufactured by Toyo Seiki Co., Ltd.), which was mixed with parts by mass and heated to 150 ° C. The melt viscosity of this composition at 150 ° C. is JIS
According to the measuring method specified in K-6862, 100 Pa by Brookfield type single cylinder rotational viscometer.
・ It was S.

Using the above-mentioned biodegradable resin composition, the resin temperature at the die outlet was set to 140 ° C. using a GPD (gear pump die) system of Yuri Roll Machine Co., Ltd.
A moisture-proof layer is formed on 0 g / m ² of paper so that the resin has a basis weight of 30 g / m ^2, and a paper of 220 g / m ² of basis weight of the resin is immediately pressed onto the moisture-proof layer to obtain the resin of the present invention. A moisture-proof paper was manufactured. At that time, a nitrogen gas atmosphere was provided between the resin charging port (hopper) and the die to prevent oxidation and hydrolysis of the resin. The resin composition charged from the hopper was defoamed by a vent type screw extruder set at 200 ° C. and then supplied to a die coater section by a pump. The moisture-proof paper obtained had a moisture permeability of 50 g / (m ²⁾ measured at 40 ° C. and 90% RH according to the method specified in JIS Z-0208.
・ 24 hours).

[0047]

Industrial Applicability According to the present invention, a moisture-proof paper having a constitution of "paper / moisture-proof layer / paper" excellent in biodegradability and moldability can be manufactured by an inexpensive and simple method.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F100 AJ02B AJ03B AK01B AK21                       AK41 AN01B BA03 BA06                       BA10A BA10C DG10A DG10C                       EC03 EH46 GB16 JA06B                       JC00B JD04B YY00B                 4L055 AG50 AG52 AG54 AG82 AH50                       AJ01 BE13 BE14 EA12 EA14                       EA25 FA30 GA47

Claims (7)

[Claims] 1. A paper / moisture-proof layer / paper comprising JIS Z-
A method for producing a moisture-proof paper having a water vapor transmission rate measured at 40 ° C. and 90% RH of 100 g / (m ² · 24 hours) or less according to the method specified in 0208, wherein the moisture-proof layer is a biodegradable resin composition. The moisture-proof layer has a basis weight of 10 to 40 g / m ² , and the moisture-proof paper is formed by a method in which two sheets of paper are laminated with a molten biodegradable resin composition. A method for producing a moisture-proof paper, which is characterized. 2. The method for producing a moisture-proof paper according to claim 1, wherein the laminating is performed in a nitrogen gas atmosphere. 3. The pasting is performed by applying the biodegradable resin composition melted by a hot melt coater to one paper and supplying the other paper on it. The method for producing a moisture-proof paper according to claim 1 or claim 2. 4. The laminating is performed by a die coater, and the die has a gear roll, and the coating amount is controlled by the rotation of the gear roll. A method for producing a moisture-proof paper according to. 5. The method for producing a moisture-proof paper according to claim 1, wherein the biodegradable resin composition contains natural rubber as a main component. 6. The method for producing a moisture-proof paper according to claim 5, wherein the biodegradable resin composition further contains a vegetable protein or a polysaccharide. 7. The biodegradable resin composition is JIS K-68.
The melt viscosity defined by 62 is 0.1 at 150 ° C.
To 1000 Pa · S, The method for producing a moisture-proof paper according to claim 1, wherein