JPH11323794A - Release paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a release paper capable of preventing permeation of a releasing agent due to excellent barrier properties, having excellent releasability by preparing a composition obtained by mixing a carboxy group-containing polyvinyl alcohol-based resin having a specific viscosity with a prescribed phosphoric ester or its salt. 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 0.1-30 pts.wt. of a phosphoric ester of the formula (R is H, an alkyl or an alkylallyl; (m) and (n) are each an integer; R' is H or an alkoxy) or its salt such as ethanolamine salt or ammonium salt 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 a coating solution having 0.1-20 wt.% 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 conducted intensive studies in view of the above circumstances. As a result, the base paper contains a carboxyl group-containing polyvinyl alcohol resin and a phosphate compound represented by the following general formula or a salt thereof. It has been found that a release paper coated with the resin composition (a) containing the above solves the above-mentioned problems, and has completed the present invention.

Embedded image (However, R represents any one of hydrogen, an alkyl group and an alkyl allyl group, m and n are integers, and R ′ represents hydrogen or an alkoxy group, respectively.)

[0005]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below.
The release paper of the present invention is a resin composition (a) comprising a carboxyl group-containing polyvinyl alcohol-based resin and a phosphate compound represented by the above general formula or a salt thereof.
Is applied to the base paper, such a carboxyl group-containing polyvinyl alcohol-based resin is not particularly limited as long as it is a polyvinyl alcohol-based resin containing a carboxyl group, and its production is not particularly limited, For example, a method of obtaining a copolymer from an unsaturated monomer having a carboxyl group and a vinyl ester-based compound, and then saponifying the copolymer, a method of simply preparing a polyvinyl alcohol-based resin having a carboxyl group having an oxyalkylene group Examples of the method include graft polymerization of a monomer, and 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 the polymerization, allyl esters of saturated carboxylic acids (allyl stearate, allyl laurate, allyl coconut oil, allyl octylate) Allyl, allyl butyrate, etc.), α-olefins (ethylene, propylene, α-hexene, α-octene, α-decene, α-dodecene, α
-Hexadecene, α-octadecene, etc.), alkyl vinyl ethers (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.), and further (meth) acrylamide, (meth) acrylonitrile, (Meth) allyl sulfonate, ethylenically unsaturated sulfonate, styrene Monomer can be copolymerized, such as vinyl chloride (vinyl ester) and may be subjected to polymerization allowed to exist than 50 mol%. No particular limitation is imposed on the copolymerization, and any known polymerization method may be used.
Solution polymerization is usually carried out using an alcohol such as methanol or ethanol as a solvent.

In such a method, as a method of charging the monomers, first, the total amount of the vinyl ester compound and a part of the carboxyl group-containing unsaturated monomer are charged to initiate 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.

[0011] In the present invention, 10 wt% aqueous solution viscosity at a shear rate of 2.5 × 10 ⁵ sec ^-1 of 40 ° C. of the carboxyl group-containing polyvinyl alcohol resins are 1~40mPa · s (more 5 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. Further, the phosphate compound or its salt blended with the above-mentioned carboxyl group-containing polyvinyl alcohol-based resin is a compound represented by the above general formula (1) or a salt thereof, such as an ethanolamine salt, an ammonium salt, Examples thereof include a sodium salt and a potassium salt, and an ethanolamine salt and an ammonium salt are preferably used.

In the present invention, a resin composition (a) containing the carboxyl group-containing polyvinyl alcohol resin and the phosphate compound or a salt thereof as described above.
The amount of the phosphate compound or salt thereof is 0.1 to 30 parts by weight based on 100 parts by weight of the carboxyl group-containing polyvinyl alcohol-based resin.
Parts by weight, more preferably 1 to 20 parts by weight, especially 2 to 20 parts by weight.
When the amount is less than 0.1 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 is lowered and the amount of the release agent permeated increases, and The adhesiveness with the release agent applied thereon is undesirably reduced.

In applying such a 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 a carboxyl group-containing polyvinyl alcohol-type resin, the compounding ratio of a carboxyl group-containing polyvinyl alcohol-type resin and this phosphate compound or its salt, etc. 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 are no particular restrictions 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, the 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.

[0016]

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 polyvinyl alcohol resin containing a carboxyl group] 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 resin at 40 ° C. of 2.5 × 10 ⁵ s
The viscosity of the 10% by weight aqueous solution at ec ^-1 was 20 mPa · s as measured by a Hercules-type rotational viscometer (manufactured by Mitsui Electric Seiki Co., Ltd.).

6.00 parts of the above carboxyl group-containing polyvinyl alcohol-based resin and 0.12 parts of a salt of the phosphate ester compound shown in Table 2 (the phosphoric acid ester compound is added to 100 parts of the carboxyl group-containing polyvinyl alcohol-based resin) 2 parts) was dissolved in 93.88 parts of water to form a coating liquid, and the coating liquid was coated on one side of a glassine paper having a basis weight of 65 g / m ² and an air permeability of 100 seconds with a resin solid content of 0.7 g / m 2. ² and dried at 105 ° C. for 2 minutes with a cylindrical rotary dryer, passed through a super calender (temperature: 80 ° C., linear pressure: 40 kg / cm), and then coated and dried. The release agent liquid (electron beam-curable solvent-free silicone [100 parts of X-52-131] manufactured by Shin-Etsu Chemical Co., Ltd.) and 30 parts of a platinum catalyst become 1.0 g / m ² in terms of solid content. After coating, Irradiation was performed 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) In accordance with the air permeability of JIS P 8117, a test piece was fixed to an Oken type air permeability tester (manufactured by Asahi Seiko Co., Ltd.), and the time (second) for passing 100 ml of air was measured. It 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 5 and Comparative Examples 1 to 2 In the same manner as in Example 1, the evaluation was carried out using salts of a carboxyl group-containing polyvinyl alcohol resin and a phosphate compound as shown in Tables 1 and 2. went. Table 3 shows the evaluation results.

[0021]

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 2.0 (〃) 20 100 〃 5 1.0 (modified with itaconic acid) 20 100 Comparative Example 1 1.0 (modified with maleic acid) 20 100 〃 20 (native) 20 100

[0022]

[Table 2] *: In the above general formula (1), R = ethyl group, m =
2, n = 2, R '= ethanol of phosphate ester of ethoxy group
Nolamine salt: In the above general formula (1), R = methyl group, m = 3,
n = 2, R ′ = ammonium of ethoxy group phosphate ester
Um salt: In the above general formula (1), R = ethyl group, m = 3,
n = 2, R ′ = ammonium of ethoxy group phosphate ester
Note) The contents in Tables 1 and 2 include carboxyl groups
Phosphoric acid based on 100 parts of polyvinyl alcohol-based resin
It shows the content of the salt of the ester compound.

[0023]

[Table 3]

[0024]

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 base paper coated with a resin composition (a) containing a carboxyl group-containing polyvinyl alcohol resin and a phosphate compound represented by the following general formula (1) or a salt thereof. And release paper. Embedded image (However, R represents any one of hydrogen, an alkyl group and an alkyl allyl group, m and n are integers, and R ′ represents hydrogen or an alkoxy group, respectively.) 2. A resin composition comprising 0.1 to 30 parts by weight of a phosphate compound represented by the following general formula (1) or a salt thereof based on 100 parts by weight of a carboxyl group-containing polyvinyl alcohol resin in a base paper. Release paper characterized in that the object (a) is coated. Embedded image (However, R represents any one of hydrogen, an alkyl group and an alkyl allyl group, m and n are integers, and R ′ represents hydrogen or an alkoxy group, respectively.) 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