JPH11323788A - Release paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a release paper having excellent releasability and recyclability by coating a paper with a composition obtained by mixing a carboxy group-containing polyvinyl alcohol-based resin having a specific viscosity with a water-soluble salt of an olefin/maleic acid copolymer. SOLUTION: A polyvinyl alcohol-based resin having 0.1-10 mol.% carboxy group content, 1-40 mPa.s viscosity of 10 wt.% aqueous solution at 2.5×10<5> sec<-1> shear rate at 40 deg.C in an amount of 100 pts.wt. is mixed with 0.05-30 pts.wt. of a water-soluble salt of an olefin/maleic acid copolymer such as a sodium salt of diisobutylene/maleic acid copolymer, etc., to prepare a composition. A base paper such as (semi)glassine paper, etc., is coated with 0.1-10 g/m<2> calculated as a solid content of the composition and provided with a layer of a releasing agent such as a silicone-based resin, etc., to give the objective release paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release paper, and more particularly to a release paper based on glassine paper or the like, which has excellent releasability, recyclability, solvent resistance (to a release agent applied), and the like. Related to release paper.

[0002]

2. Description of the Related Art Conventionally, release paper has been used in various fields as a base material for adhesive labels, adhesive tapes, adhesive sheets and the like. Such a release paper generally has a configuration in which a release agent layer is provided on the surface of the base paper, and usually, the release agent does not penetrate into the paper and has good release properties on the surface of the base paper. In order to form a mold agent layer, a polyolefin resin layer such as polyethylene is provided at the interface, or a barrier layer such as a polyvinyl alcohol resin, carboxymethyl cellulose, casein, polyvinyl acetate emulsion is provided. I have.

[0003]

However, when a polyolefin resin layer is provided, the barrier effect is sufficient, but considering the recent recycling of paper, the treatment of the resin is a major problem. On the other hand, in the case of a layer made of a conventional polyvinyl alcohol-based resin, etc., the barrier problem is not sufficient although the recycling problem is cleared, and a barrier layer that satisfies both the recyclability and the barrier property is provided. Therefore, an excellent release paper is desired.

[0004]

The inventors of the present invention have made intensive studies in view of the above circumstances and found that the base paper contains a carboxyl group-containing polyvinyl alcohol resin and a water-soluble salt of an olefin / maleic acid copolymer. The present inventors have found that a release paper coated with the resin composition (a) solves the above-mentioned problems, and has completed the present invention.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below.
The release paper of the present invention comprises a base paper coated with a resin composition (a) containing a carboxyl group-containing polyvinyl alcohol-based resin and a water-soluble salt of an olefin / maleic acid copolymer. The carboxyl group-containing polyvinyl alcohol-based resin is not particularly limited as long as it is a carboxyl group-containing polyvinyl alcohol-based resin, and the production thereof is not particularly limited, and examples thereof include a carboxyl group-containing unsaturated monomer and vinyl. After obtaining a copolymer from the ester compound, a method of saponifying the copolymer, a method of graft-polymerizing a monomer having an oxyalkylene group to a polyvinyl alcohol-based resin having a carboxyl group, and the like, The former method is practical in terms of resin production and performance.

Hereinafter, the former method will be specifically described. Examples of unsaturated monomers having a carboxyl group include ethylenically unsaturated dicarboxylic acids (maleic acid, fumaric acid,
Itaconic acid), or an ethylenically unsaturated carboxylic acid monoester (monoalkyl maleate, monoalkyl fumarate, monoalkyl itaconate), or an ethylenically unsaturated dicarboxylic acid diester (dialkyl maleate, dialkyl fumarate) Esters, dialkyl itaconates), monomers such as ethylenically unsaturated carboxylic anhydrides (maleic anhydride, itaconic anhydride), or (meth) acrylic acid, and salts thereof. Saturated carboxylic acid monoesters or salts thereof are preferably used.

[0007] The vinyl ester compounds include:
Vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatate, vinyl palmitate, vinyl stearate, etc. can be used alone or in combination, but vinyl acetate is particularly practical. High in nature.

In the present invention, in addition to the above-mentioned monomer having a carboxyl group and a vinyl ester compound during polymerization, allyl esters of saturated carboxylic acids (allyl stearate, allyl laurate, allyl coconut fatty acid) , Allyl octylate, allyl butyrate, etc.), α-olefins (ethylene, propylene, α-hexene, α-octene, α-decene, α-dodecene, α-hexadecene,
α-octadecene, etc.), alkyl vinyl ether (propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, tetradecyl vinyl ether, hexadecyl vinyl ether, octadecyl vinyl ether, etc.), alkyl allyl ether (propyl allyl ether, butyl allyl) Ether, hexyl allyl ether, octyl allyl ether, decyl allyl ether, dodecyl allyl ether, tetradecyl allyl ether, hexadecyl allyl ether, octadecyl allyl ether, etc.), furthermore, (meth) acrylamide, (meth) acrylonitrile, (meth) Allyl sulfonate, ethylenically unsaturated sulfonate, styrene, vinyl chloride, etc. (Vinyl ester) a monomer which can be copolymerized may be performed polymerization allowed to exist than 50 mol%. There is no particular limitation on the copolymerization, and any known polymerization method may be used, but solution polymerization is usually performed using an alcohol such as methanol or ethanol as a solvent.

In such a method, as a method of charging the monomers, first, the entire amount of the vinyl ester compound and a part of the unsaturated monomer having a carboxyl group are charged to start polymerization, and the remaining unsaturated monomer is charged. Any method may be used, such as a method of continuously or dividedly adding during the polymerization period or a method of batch charging. The copolymerization reaction is carried out using a known radical polymerization catalyst such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, and lauroyl peroxide. The reaction temperature is selected from the range of 50 ° C. to the boiling point.

The copolymer obtained as described above is then saponified to form a carboxyl group-containing polyvinyl alcohol resin. In the saponification, the copolymer is dissolved in an alcohol, an acetic ester or a mixed solvent thereof, and is carried out in the presence of an alkali catalyst. Examples of the alcohol include methanol, ethanol, and butanol, and examples of the acetate include methyl acetate and ethyl acetate. The concentration of the copolymer in the alcohol is 20 to 5
It is selected from the range of 0% by weight. As the saponification catalyst, it is necessary to use an alkali catalyst such as an alkali metal hydroxide or an alcoholate such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate and potassium methylate. It is necessary to use the catalyst in an amount of 1 to 100 millimoles equivalent to the vinyl ester compound.

In such a case, the saponification temperature is not particularly limited, but is usually preferably selected from the range of 10 to 70 ° C, more preferably 30 to 40 ° C. The reaction is usually carried out for 2 to 3 hours, and the preferred degree of saponification is 10 to 100 mol%.
Particularly preferably 50 to 100 mol%, particularly preferably 7 to 100 mol%
It is selected from the range of 0 to 100 mol%. When a vinyl alcohol component is contained, the present invention is not limited to the above-mentioned method. For example, a method in which an alkylene oxide is post-reacted with polyvinyl alcohol (partially saponified or completely saponified) can be used. Thus, a carboxyl group-containing polyvinyl alcohol-based resin is obtained, and the content of such a carboxyl group is preferably 0.1 to 10 mol%, more preferably 0.5 to 5 mol%. If the amount is less than 0.1 mol%, the solvent resistance to the solvent-based release agent to be applied is low, and if it exceeds 10 mol%, the solubility when used as a coating liquid is undesirably poor.

Further, in the present invention, the viscosity of a 10% by weight aqueous solution of a carboxyl group-containing polyvinyl alcohol resin at a shear rate of 2.5 × 10 ⁵ sec ^-1 at 40 ° C. is ^{1 to} 40 mPa · s (more preferably 5 to 40 mPa · s). 30mPa · s)
It is preferable that the viscosity of the aqueous solution is 1 mPa ·
If it is less than s, the barrier property of the paper decreases and the amount of the release agent permeated increases, while if it exceeds 40 mPa · s, the coating properties of the coating liquid decrease, which is not preferable. The water-soluble salt of the olefin / (anhydride) maleic acid copolymer blended with the above-mentioned carboxyl group-containing polyvinyl alcohol-based resin is not particularly limited, and diisobutylene (2,2,4-trimethylpentene). ( Ammonium, sodium and calcium salts of maleic anhydride copolymer, pentene / (maleic anhydride) maleic acid copolymer, hexene / (maleic anhydride) maleic acid copolymer, nonene / (maleic anhydride) maleic acid copolymer And ammonium salts such as diisobutylene / maleic acid copolymer, pentene / maleic anhydride copolymer, and hexene / maleic anhydride copolymer, and sodium salts and calcium salts are preferably used.

In the present invention, the carboxyl group-containing polyvinyl alcohol resin and the olefin
The resin composition (a) containing the water-soluble salt of the (anhydride) maleic acid copolymer is used. The amount of the water-soluble salt of the copolymer is 100 parts by weight of the carboxyl group-containing polyvinyl alcohol resin. Is preferably 0.05 to 30 parts by weight, more preferably 0.1 to 25 parts by weight,
When the amount is less than 0.05 part by weight, the effect of the compounding is poor. On the other hand, when the amount exceeds 30 parts by weight, the barrier property of the paper decreases and the amount of the release agent permeated increases. Adhesion with a release agent applied thereon is undesirably reduced.

In applying the resin composition (a) to a base paper, it is generally used as a coating solution dissolved in water, but a solvent system can also be used. The type of solvent is
What is necessary is just to select suitably according to the characteristics of the carboxyl group-containing polyvinyl alcohol resin, the compounding ratio of the carboxyl group-containing polyvinyl alcohol resin, and the water-soluble salt of an olefin / maleic acid copolymer. For example, a solvent having a relatively low degree of saponification can be obtained in the form of a paste, so that the solvent used for polymerization or saponification may be used as it is, or solvent replacement may be performed if necessary.

There is no particular limitation on the preparation of such a coating solution, and in short, water (or a solvent) and the above resin composition (a) may be mixed. The concentration may be appropriately adjusted, but the particularly preferred concentration of the resin composition (a) is usually 0.1 to 20% by weight, more preferably 1 to 10%, in consideration of workability and the like.
It is selected from a range of about weight%. Further, in the present invention, a water-proofing agent such as glyoxal, epichlorohydrin, ammonium zirconium carbonate, tetra-n-butyl titanate, tetra-n-isopropyl titanate, a urea resin, or the like is further added to the coating liquid, if necessary. Agent,
Surfactants, preservatives, insect repellents, rust inhibitors, known additives such as thickeners can also be added, and other paper processing agents as long as the characteristics of the present invention are not impaired, for example, Other conventionally known resins such as polyvinyl alcohol, starch, carboxymethyl cellulose, acrylic latex and SBR latex can also be mixed.

Thus, such a coating liquid is applied to the base paper. In the coating, known coating methods such as a size press coat method, a roll coater method, an air yard method, a blade coater method, and a gate roll coater method are used. An arbitrary method is adopted, and the coating amount is such that the total amount of the carboxyl group-containing polyvinyl alcohol-based resin and the hydrophilic group-containing fluorine-based compound is 0.1 to 10 g / m ² (in terms of solid content), particularly preferably 0.1 to 10 g / m ² . It is appropriate that the amount is about 5 to 5 g / m ² (same as above). The base paper is not particularly limited, and examples thereof include glassine paper, semi-glassine paper, kraft paper, Japanese paper, high-quality paper, and nonwoven fabric. Gransin paper and semi-glassine paper are particularly preferably used. Thus, a layer of the resin composition (a) is formed on the base paper.
Usually, a release agent layer is formed on this surface to form a release paper. Such a release agent is not particularly limited, and a silicone-based resin, a fluorine-based resin, or the like is used.

[0017]

The present invention will be specifically described below with reference to examples. In the examples, “parts” and “%” are based on weight unless otherwise specified.

Example 1 [Preparation of a carboxyl group-containing polyvinyl alcohol resin] In a polymerization vessel, 500 parts of vinyl acetate and 3.4 parts of maleic acid were added.
And 85 parts of methanol, the mixture was heated in a stream of nitrogen with stirring and refluxed at 60 ° C. for 30 minutes, and then azobisisobutyronitrile was added in an amount of 0.08 mol% based on vinyl acetate.
In addition, a methanol solution of maleic acid was charged and added dropwise so that the degree of modification was 1.0 mol%, polymerization was carried out for 6 hours. After the reaction was completed, methanol vapor was blown to remove unreacted monomers, and the copolymer A methanol solution was obtained. Next, the obtained methanol solution was diluted to 40% with methanol. Further, sodium hydroxide was added to the vinyl acetate in the copolymer at 40 mmol% to effect saponification. The resulting saponified product was filtered, dried at 70 ° C., and dried at a carboxyl group-containing polyvinyl alcohol resin (degree of saponification). 94.0 mol%). The shear rate of the obtained carboxyl group-containing polyvinyl alcohol-based resin at 40 ° C. of 2.5 × 10 ⁵ c
The viscosity of a 10% by weight aqueous solution at m ^-1 was measured with a Hercules-type rotational viscometer (manufactured by Mitsui Electric Seiki Co., Ltd.).
It was 20 mPa · s.

[Preparation of water-soluble salt of diisobutylene / maleic acid copolymer] In a polymerization vessel, 168 parts of vinyl acetate, 98 parts of maleic anhydride and 250 parts of toluene are charged, and the temperature is raised to 90 to 95 ° C. with stirring. Thereafter, a solution prepared by dissolving 4.8 parts of benzoyl peroxide in 50 parts of toluene was added and reacted for 6 hours. Then, the reaction solution was poured into methanol to precipitate a white powder, which was filtered and dried to obtain diisobutylene. 205 parts of a maleic anhydride copolymer were obtained. Next, 68 parts of 25% ammonia water and 329 parts of water were added to 105 parts of the copolymer, and the mixture was reacted at 80 ° C. for 1 hour to obtain an aqueous solution of an ammonium salt of a diisobutylene / maleic anhydride copolymer.
Water was removed at 60 ° C. under reduced pressure to obtain an ammonium salt of the copolymer.

5.8 parts of the above carboxyl group-containing polyvinyl alcohol resin and 1.0 part of an ammonium salt of a diisobutylene / maleic anhydride copolymer (100 parts of the carboxyl group-containing polyvinyl alcohol resin are mixed with diisobutylene / anhydrous (17 parts of an ammonium salt of a maleic acid copolymer) was dissolved in 93.2 parts of water to form a coating solution,
Coating liquid a basis weight 65 g / m ^2, on one side of glassine paper air permeability 100 sec was applied so as to 0.7 g / m ² of resin solids, at at 105 ℃ cylindrical rotary drier After drying for 2 minutes, further super calendar (temperature: 80 ° C, linear pressure:
40 kg / cm), and then 100 parts of a release agent liquid (electron beam-curable solventless silicone [X-52-131] manufactured by Shin-Etsu Chemical Co., Ltd.) and a platinum catalyst 30 on the coating / drying surface. Part) was applied to a solid content of 1.0 g / m ² , and then irradiated with an electron beam to form a release agent layer to obtain a release paper. The obtained release paper was evaluated for barrier properties (air permeability) and releasability in the following manner.

(Barrier property) According to the air permeability of JIS P 8117, Oken type air permeability tester (manufactured by Asahi Seiko Co., Ltd.)
The test piece was fixed to the sample, and the time (second) for passing 100 ml of air was measured. (Releaseability) An acrylic emulsion adhesive (manufactured by Nippon Carbide Co., Ltd., "Nicazole L-
145 ”) with a reverse roll coater so that the coating amount is 25 g / m ^2, and is dried with hot air at 130 ° C., and then glued with high-quality paper having a basis weight of 65 g / m ² . Peel strength at the time of peeling at 3 m / min (g /
50 mm) and evaluated as follows. ○ --- less than 100 g / 50 mm △ ---- 100 to less than 200 g / 50 mm × --- 200 g / 50 mm or more The obtained release paper is easily dissolved in water by ordinary recycling work and recovered as used paper. It was also possible.

Examples 2 to 4, Comparative Examples 1 to 2 Carboxyl group-containing polyvinyl alcohol resins and olefins as shown in Tables 1 and 2 according to Example 1.
Evaluation was similarly performed using a water-soluble salt of a maleic acid copolymer. Table 3 shows the evaluation results.

[0023]

TABLE 1 Carboxyl group-containing polyvinyl alcohol-based resin Carboxyl group content (mol%) Aqueous solution viscosity (mPa · s) Content (parts) Example 1 1.0 (maleic acid-modified) 20 100 〃 2 2.0 ( 〃) 40 100 ３ 31.0 (〃) 20 100 ４ 4 1.0 (modified with itaconic acid) 20 100 Comparative Example 1 1.0 (modified with maleic acid) 20 100 〃 20 (unmodified) 20 100

[0024]

[Table 2] Water-soluble salt of olefin / maleic anhydride copolymer Olefin species Water-soluble salt species Content (parts) Example 1 Diisobutylene ammonium salt 17 ブ 2 Penten sodium salt 17〃3 Hexene ammonium salt 9〃4 Di Isobutylene sodium salt 17 Comparative Example 1 --- ---- 0 (not blended) 〃2 Diisobutylene ammonium salt 17 Note) The contents in Tables 1 and 2 are based on 100 parts of carboxylic acid-containing polyvinyl alcohol-based resin. It shows the content of a water-soluble salt of a maleic acid copolymer.

[0025]

[Table 3]

[0026]

The release paper of the present invention has a good barrier property because the base paper is coated with the specific resin composition (a), so that the release agent can be prevented from penetrating. It has good moldability and can be easily dissolved in water by ordinary recycling work and can be recovered as waste paper, and is useful as a base material for adhesive labels, heat-sensitive labels, adhesive tapes, adhesive sheets, and the like.

Claims (4)

[Claims] 1. A release paper comprising a base paper coated with a resin composition (a) containing a carboxyl group-containing polyvinyl alcohol resin and a water-soluble salt of an olefin / maleic acid copolymer. 2. A resin composition (a) in which 0.05 to 30 parts by weight of a water-soluble salt of an olefin / maleic acid copolymer is mixed with 100 parts by weight of a carboxyl group-containing polyvinyl alcohol resin in a base paper. Release paper characterized by being coated. 3. The release paper according to claim 1, wherein the content of the carboxyl group in the carboxyl group-containing polyvinyl alcohol resin is 0.1 to 10 mol%. 4. A shear rate of 2.5 × 10 ⁵ sec ^{-1 at} 40 ° C. of a carboxyl group-containing polyvinyl alcohol resin.
Of 10% by weight aqueous solution at 1 to 40 mPa · s
The release paper according to any one of claims 1 to 3, wherein