JPH0827442A - Release paper - Google Patents

Abstract

PURPOSE:To obtain a release paper, reutilizable as a recycled pulp by a conventional waste paper recycling process, hardly causing the curl in a tacky paper even in a printing or a copying process and capable of constituting the tacky paper excellent in aspects of operability and quality characteristics. CONSTITUTION:This release paper is obtained by laminating an undercoat layer and a release agent layer onto a base paper. The undercoat layer is formed out of a copolymer, comprising a monomer composition of (a) 2-40wt.% monomer containing an ethylenically unsaturated carboxylic acid, (b) 50-90wt.% 4-10C alkyl ester monomer of (meth)acrylic acid and (c) 0-40wt.% other monomers copolymerizable with the monomers, solubilized to water by neutralization with an alkaline substance and having -60 to +20 deg.C glass transition temperature and a pigment as principal components. The amount of the pigment is 50-150 pts.wt. based on 100 pts.wt. solid content of the copolymer.

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, it is reusable by a recycled pulping process of waste paper, and
The present invention relates to a release paper capable of forming a pressure-sensitive adhesive paper that does not curl and is excellent in paper passing suitability in a printing process or a copying process.

[0002]

2. Description of the Related Art Adhesive paper is used for labels, stickers, stickers,
It is used as a patch for a wide range of purposes such as commercial use, office use, and household use. This adhesive paper is generally constructed by laminating a surface substrate, an adhesive, and release paper in this order. The surface substrate is paper, film, metal foil, etc., and the release paper is high-density paper such as glassine paper, release coated base paper such as clay coated paper, poly-laminated paper, etc., coated with a release agent such as silicone compound or fluorine compound. What has been used is being used. The pressure-sensitive adhesive includes solvent-type pressure-sensitive adhesive, emulsion-type pressure-sensitive adhesive, hot melt-type pressure-sensitive adhesive and the like.

The adhesive paper which is such a laminated body is apt to curl due to the release paper. In a general production process of an adhesive paper, a release agent is applied to a release paper base paper and dried, an adhesive is applied to the release agent surface, dried, and then bonded to a surface base material. That is, the release paper base paper is coated and dried twice with the release agent and the pressure-sensitive adhesive in the manufacturing process to shrink, and the reactivity with water is extremely high.

Therefore, if the release paper of the adhesive paper absorbs moisture and absorbs water due to changes in temperature and humidity of the surrounding environment, curling of the adhesive paper will occur immediately. In particular, when a high-beating, high-density base paper such as glassine paper is used as the release paper base paper, it shrinks more than ordinary paper when dried, and the interfiber voids that absorb the expansion of fibers caused by moisture absorption are absorbed. Since it is extremely small, the occurrence of curling is particularly remarkable.

The curl of the adhesive paper is, for example, printed on the adhesive paper,
Die cutting (punching), sheet cutting, etc. are performed at the stage of processing into labels, seals, etc., causing problems such as poor paper feeding, paper misalignment, and print misalignment. Further, the curl of the pressure-sensitive adhesive paper causes a paper passing failure or a transfer failure when copying with a copying machine or the like as an application. Therefore, the occurrence of curling of the pressure-sensitive adhesive paper becomes a very serious obstacle to workability and quality characteristics.

As a method of correcting the curled adhesive paper, there is a method of using a curl breaker or the like that bends the adhesive paper in a direction opposite to the curl direction at an acute angle. Further, as a method for suppressing the occurrence of curling of the adhesive paper, a method of keeping the temperature and humidity of the surrounding environment constant by using an air conditioner, steam damping, or the like has been proposed. However, in addition to the complexity of the process, the effect is insufficient, and the satisfactory result is not always obtained.

Further, a poly-laminated release paper which is very often used when constructing an adhesive paper is "Paper is revived-Think of tomorrow of old paper-" (edited by Paper Industry Times Co., Ltd., March 1981).
It is difficult to reuse it as recycled pulp in a normal waste paper recycling process such as that issued on the 15th of March. Therefore, while the reuse of waste paper has become a social requirement, the release paper is currently landfilled or incinerated with little recovery.

[0008]

From the above circumstances, it can be reused as recycled pulp by a normal waste paper recycling process, and the release agent and the adhesive are applied and dried twice in the production process of the adhesive paper. Provided is a release paper capable of constituting a pressure-sensitive adhesive paper which is excellent in workability and quality characteristics, and has less curling even in a printing process or a copying process even after passing through the sheet.

[0009]

The present invention provides a release paper comprising a base paper and an undercoat layer and a release agent layer laminated on at least one side of the base paper, which comprises the following monomer compositions (a), (b) and (c). The copolymer is neutralized with an alkaline substance to give a water-soluble copolymer, which is mainly composed of a copolymer having a glass transition temperature of −60 to 20 ° C. and a pigment, and has a solid content of 100 parts by weight of the copolymer. On the other hand, the release paper is characterized in that an undercoat layer having a pigment content of 50 to 150 parts by weight is provided. (A) Ethylenically unsaturated carboxylic acid-containing monomer: 2 to 4
0 wt% (b) (meth) C ₄ -C ₁₀ alkyl ester monomers of acrylic acid: 50 to 90 wt% (c) these monomers and other copolymerizable monomers: 0
40% by weight

[0010]

The ethylenically unsaturated carboxylic acid-containing monomer that constitutes the above specific water-soluble copolymer used in the present invention includes, for example, (meth) acrylic acid, crotonic acid,
Maleic acid, itaconic acid, fumaric acid, monoalkyl maleic acid, monoalkyl fumaric acid, monoalkyl itaconic acid and the like can be mentioned, and at least one of them can be used.

The ethylenically unsaturated carboxylic acid-containing monomer of the present invention improves the effect of preventing the penetration of the release agent into the silicone resin and the re-disintegration property in the used pulp recycling process. The amount of the ethylenically unsaturated carboxylic acid-containing monomer used is preferably about 2 to 40% by weight, based on the total solid content of the monomers, and most preferably about 2 to 20% by weight, This is preferable because the effect of preventing the penetration of the silicone resin is remarkably improved, and the re-disaggregation property is remarkably improved. However, if the amount of the ethylenically unsaturated carboxylic acid-containing monomer used is less than 2% by weight, the re-disaggregation property in the waste paper recycling pulp treatment becomes insufficient, and conversely, if it exceeds 40% by weight, the drying property becomes poor. It is not preferable because the film becomes sufficient and the film becomes hard and the curl improving effect is reduced.

On the other hand, C _{4 of} (meth) acrylic acid, which constitutes the above-mentioned specific water-soluble copolymer used in the present invention,
To C ₁₀ alkyl ester monomers include, for example, butyl (meth) acrylate, hexyl (meth) acrylate,
Octyl (meth) acrylate, (meth) acrylic acid-2
-Ethylhexyl and the like can be mentioned, and at least one of them can be used.

The proportion of these C ₄ -C ₁₀ alkyl ester monomers of (meth) acrylic acid in the copolymer is
It is adjusted in the range of 50 to 90% by weight. If the amount used is less than 50% by weight, the film becomes hard and the effect of improving the curl is deteriorated. On the contrary, if it is more than 90% by weight, the film becomes too soft and blocking is deteriorated, which is not preferable.

Further, a monomer of an ethylenically unsaturated carboxylic acid-containing monomer, which constitutes the above specific water-soluble copolymer used in the present invention, a C ₄ -C ₁₀ alkyl ester of (meth) acrylic acid Other monomers that can be copolymerized with the body include
For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, vinyl acetate, vinyl chloride, vinylidene chloride, (meth) acrylonitrile, Styrene, ethylene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth)
Acrylate, (poly) ethylene glycol di (meth)
Acrylate, dipropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, divinylbenzene, 1,4-butanediol Di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N- Butoxymethyl (meta)
Acrylamide, N, N′-methylenebis (meth) acrylamide, sodium vinyl sulfonate, sodium p-styrene sulfonate, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphoxyethyl methacrylate ethanolamine half salt, 3-allyloxy- Two
-Sodium hydroxypropane sulfonate, sodium polyoxyethylene styrenated phenylsulfate, sodium glycerin monoallyl ether monosulfosuccinate, sodium 2-sulfoethyl methacrylate, sodium acrylamidostearate, etc., and use at least one of them You can

The proportion of these other copolymerizable monomers in the copolymer is adjusted in the range of 0 to 40% by weight based on the total monomers. Although the effect of the present invention can be obtained even when other monomer is not used here, if the amount of the other monomer used is small, the effect of suppressing the penetrability of the release agent of the coating tends to be poor. On the other hand, when it is 40% by weight or more, the coating becomes too hard and the curl improving effect is lowered, which is not preferable.

In the release paper of the present invention, the ethylenically unsaturated carboxylic acid-containing monomer is contained in an amount of 2 to 30% by weight and C _{4 to} C _10.
(Meth) acrylic acid ester having alkyl group of 50
A copolymer obtained by copolymerizing 80% by weight to 2% to 40% by weight of another monomer such as (meth) acrylonitrile is more preferably used.

The acrylic resin film obtained by drying the above copolymer has a gel fraction of 55% by weight with respect to toluene.
It is desirable that the amount is at least 60% by weight. Incidentally, if the gel fraction of toluene of the acrylic resin film is less than 55% by weight, the desired effect of the present invention cannot be obtained, and not only the original performance of the release agent coated on the undercoat layer cannot be obtained, The peeling force of the pressure-sensitive adhesive paper obtained by using such a release paper changes with time and becomes very heavy.

Here, the gel fraction with respect to toluene is a value obtained by the following formulation. It is formed on the Teflon sheet so that the film thickness of the acrylic resin is 0.3 to 0.5 mm (after drying). The drying condition is 50 ° C./24 hours. Next, the film prepared under the above conditions is applied to 3c
Cut into m squares, soak in toluene for 24 hours, and then at 105 ℃ for 3 hours.
The solvent is completely volatilized by drying for a period of time, the weight change before and after the immersion is measured, and the gel fraction is calculated by the following formula (Equation 1).

[0019]

[Equation 1]

Further, in the present invention, if necessary,
For example, melamine, epoxy, isocyanate, and aziridine compounds may be used as a crosslinking agent.

The method for producing the above copolymer is not particularly limited, and for example, a solution polymerization method in the presence of water, a solvent, a chain transfer agent, a polymerization initiator, etc., a chain transfer agent, or a polymerization method. It is produced by a method such as emulsion polymerization in the presence of an initiator, an emulsifier, a dispersant and the like in an aqueous system.

The concentration of the monomer during the polymerization is usually 30 to 70.
About 100% by weight, preferably about 40 to 60% by weight is suitable. Examples of the polymerization initiator used during the polymerization include persulfates such as potassium persulfate and ammonium persulfate, 2,2′-azobisisobutyronitrile, 2,2 ′.
-Azo compounds such as azobis (2,4-dimethylvaleronitrile), hydrogen peroxide, benzoyl peroxide,
Examples thereof include so-called redox type polymerization initiators composed of peroxides such as lauryl peroxide and combinations of ammonium persulfate with sodium sulfite, acidic sodium sulfite and the like. The amount of the above-mentioned polymerization initiator to be used is usually about 0.2 to 2% by weight, preferably 0.1% to the total amount of the monomers used for the polymerization.
It is desirable to set it to about 3 to 1% by weight. The polymerization reaction is usually performed at about 60 to 100 ° C. for about 2 to 8 hours.

The glass transition temperature of the copolymer of the present invention is -6.
It is preferably from 0 to 20 ° C, more preferably -4.
Those having a temperature of 0 to 10 ° C are selectively used. When the glass transition temperature of the copolymer is lower than -60 ° C, the tackiness of the coating becomes too strong, while when it exceeds 20 ° C, the obtained coating becomes too hard and becomes less practical. .

In the present invention, the glass transition temperature Tg of the copolymer is calculated based on the following general formula (2).

[0025]

[Equation 2]

The specific copolymer as described above has a suitable carboxyl group in the copolymer such as sodium hydroxide, potassium hydroxide, ammonia, various primary, secondary, and tertiary amines. It is made water-soluble by neutralizing it with a strong alkaline substance and has a concentration of 20 to 60% by weight, preferably 30.
It is used by adjusting to about 50% by weight.

It is essential that the undercoat layer of the present invention contains a pigment as a main component, and by providing the undercoat layer containing a pigment, blocking of the undercoat layer can be suppressed. Further, it is possible to improve the stability of the coating material when the undercoat layer is formed by coating. As the pigment to be contained in the undercoat layer, usual inorganic organic pigments can be used, and examples thereof include oxides, hydroxides, sulfides, carbonates of various metals such as magnesium, calcium, zinc, barium, titanium, aluminum, antimony and lead. Examples thereof include salts, sulfates or silicate compounds, and solid polymer fine powders of polystyrene, polyethylene, polyvinyl chloride and the like. Among them, kaolin, talc, silica, colloidal silica, gypsum, barite powder, alumina white,
Blocking can be efficiently prevented by using an inorganic pigment such as gloss white, satin white, titanium oxide, calcium carbonate, and white carbon. Furthermore,
The use of kaolin and calcium carbonate is preferable because it can efficiently prevent the penetration of the release agent. Also,
The average particle diameter of the pigment is preferably 0.1 to 10 μm. If the average particle size of the pigment is less than 0.1 μm, the pigment may permeate into the substrate, and blocking may not be effectively prevented. If it exceeds 10 μm, the undercoat layer There is a possibility that the porosity of will increase and the function of preventing the penetration of the release agent will deteriorate.

The amount of the pigment contained in the undercoat layer is 50 to 150 based on 100 parts by weight of the solid content of the copolymer.
It is desirable to adjust to the range of parts by weight. When the amount of the pigment used is less than 50 parts by weight, the adhesiveness of the film becomes too strong, while when it exceeds 150 parts by weight, the effect of preventing the release agent from penetrating the film becomes insufficient and appropriate release performance can be obtained. Absent.

The undercoat layer of the present invention is prepared by applying it to a coating material, and in the coating material, for example, methyl cellulose, ethyl cellulose,
Various water-soluble natural polymers such as cellulose derivatives such as hydroxyethyl cellulose and carboxymethyl cellulose, dextrin, acid-treated starch, oxidized starch, cross-linked starch, starch ester, starch derivatives such as graft copolymer starch; ethylene glycol, glycerin, Polyhydric alcohols such as trimethylolpropane and diethylene glycol; Water-soluble plasticizers such as polyalkylene glycols such as polyethylene glycol and polypropylene glycol;
Crosslinking agents such as urea-formaldehyde resin, melamine-formaldehyde resin, polyamide-polyamine-epichlorohydrin resin, polyacrylamide resin, epoxy resin; further inorganic salts; fillers; defoamers; wetting agents; leveling agents; curing agents; A viscous agent; a film-forming aid and the like can be added as appropriate.

The method of applying or impregnating the base paper with the coating material for the undercoat layer is, for example, air knife coater, roll coater, gravure coater, bar coater, blade coater, rod blade coater, lip coater,
Devices such as curtain coaters and various size press coaters are used. The coating amount of the undercoat layer is 0.1 to 0.1 in dry weight
It is preferably adjusted within the range of about 20 g / m ² , and particularly preferably about 1 to 10 g / m ² .

The release paper of the present invention has a basis weight of 30 to 30 square meters as a base paper.
Various fiber sheets having a thickness of about 300 g / m ² and a thickness of about 30 to 300 μm are used. Although various silicone compounds and fluorine compounds are applied according to a conventional method as the release agent applied on the undercoat layer, the solvent-type silicone evaporates the solvent and cures the silicone with a large amount of heat energy (high temperature). ) Is required, and when the water content of the base material is dissipated, an undercoat layer,
When a pinhole is generated in the release agent layer and the surface substrate of the adhesive paper using this release paper is released from the release paper, the adhesive remains on the release paper (pinhole portion on the release agent layer) It is desirable to use solvent-free silicone, because the labeler's suitability for passing through the paper becomes poor and the release paper curls significantly. In particular, among the solventless silicone resins, the radiation-curable silicone resin is more effective because it does not require heat during curing. Further, since the undercoat layer contains a pigment, the wettability is improved when the solventless silicone is applied, and further the adhesion between the undercoat layer and the release agent layer is improved. In the treatment, the silicone release agent is also easily removed together with the pigment.

The release paper of the present invention can be used as a pressure-sensitive adhesive paper according to a conventional method, for example, by coating a solvent-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, a hot-melt-type pressure-sensitive adhesive, etc. It is damp and finished into an adhesive paper.

The release paper of the present invention obtained as described above can be reused as recycled pulp particularly by a normal waste paper recycling process, and further, curling can be effectively prevented, and a pressure-sensitive adhesive paper manufacturing process, It is possible to obtain a pressure-sensitive adhesive paper and a pressure-sensitive adhesive product which are excellent in the pressure-sensitive adhesive paper processing step, the workability of end use and the quality aptitude.

[0034]

The present invention will be more specifically described with reference to the following examples, but the present invention is not limited to these examples. The coating amount, the number of parts, the ratio, etc. in the examples are all shown by the weight of the dry solid content.

Example 1 [Preparation of Copolymer] 120 g of isopropyl alcohol and 56 g of water were placed in a 1-liter four-necked flask equipped with a stirrer, cooler, dropping funnel, nitrogen suction tube and thermometer.
Is charged, and the temperature is raised to the reflux temperature under nitrogen flow and stirring.
Butyl acrylate 60g, acrylic acid 30 in the dropping funnel
g, acrylonitrile 9 g, N-methylol acrylamide 1 g, 2,2′-azobisisobutyronitrile 0.
5 g was charged, this homogeneous solution was added dropwise over 2 hours, and after the addition, aging was carried out for 2 hours.

The polymerization and aging are carried out at the reflux temperature,
After completion of the aging, the contents of the flask were cooled to 40 ° C., a sodium hydroxide aqueous solution was added to carry out a neutralization reaction, and after completion of the reaction, the temperature was raised to remove isopropyl alcohol from the system by azeotropic distillation with water. After cooling, it was diluted to a concentration of 30% to obtain a water-soluble copolymer (1) used in the present invention. The obtained copolymer had a glass transition temperature of -11 ° C and a gel fraction of 75%.

[Preparation of Coating Material for Undercoat Layer] The coating material for undercoat layer was prepared to have a concentration of 40% with the following composition. 100 parts of the above-mentioned copolymer (1), 100 parts of wet heavy calcium carbonate (trade name, Hydrocurve K-9, manufactured by Bihoku Powder Chemical Co., Ltd.) (average particle size: 0.6 μm), lubricant (commodity) Name, Nopcoat C-104, manufactured by San Nopco Co., Ltd. 1 part, antifoaming agent (trade name, Nopco 1407K, manufactured by San Nopco Co., Ltd.) 0.6 part.

[Formation of Undercoat Layer as Base Paper for Release Paper] A dry weight of 8 g / m ² with a rod blade coater was applied to a wood free paper having a basis weight of 40 g / m ² and a thickness of 55 μm.
Was coated and dried to obtain a base paper for release paper having an undercoat layer.

[Release Paper] A solvent-free silicone release agent (trade name: KNS-320, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the undercoat layer surface of the base paper for release paper with a gravure coater at a coating amount of 0.9 g / m 2. The release paper of the present invention was obtained by applying and heat-curing so as to be ² .

[Adhesive Paper] An adhesive (trade name, Nicazole L-145, manufactured by Nippon Carbide Industry Co., Ltd.) was coated on the surface of the obtained release paper with a reverse roll coater so that the dry weight was 17 g / m ^2. After that, basis weight 64g / m ²
An adhesive sheet was obtained by pasting the same with high quality paper (trade name, TWF55, manufactured by Shin Oji Paper Co., Ltd.).

Example 2 An undercoat layer coating material having a concentration of 50% was prepared in the same manner as in Example 1 except that the wet heavy calcium carbonate was changed to 130 parts. A base paper for release paper was obtained, and the release paper of the present invention was obtained in the same manner as in Example 1 below. An adhesive paper was manufactured in the same manner as in Example 1 using the obtained release paper.

Example 3 In Example 1, 60 parts of wet heavy calcium carbonate,
A base paper for release paper was obtained in the same manner as in Example 1 by using 3 parts of lubricant, 0.8 part of defoaming agent and 38% of concentration to prepare a base paper for release paper. A release paper of the present invention was obtained. An adhesive paper was manufactured in the same manner as in Example 1 using the obtained release paper.

Example 4 In Example 1, wet heavy calcium carbonate was used as kaolin (trade name, Ultra White-90, manufactured by Engelhard) (average particle size: 0.4 μm) to prepare a coating material for an undercoat layer. A base paper for release paper was obtained in the same manner as in Example 1, and the release paper of the present invention was obtained in the same manner as in Example 1. An adhesive paper was manufactured in the same manner as in Example 1 using the obtained release paper.

Example 5 [Preparation of Copolymer] An emulsified monomer mixture liquid was prepared in the following formulation. Butyl acrylate 270 g, acrylonitrile 113 g, acrylic acid 15 g, N-methylol acrylamide 2 g, polyoxyethylene nonylphenyl ether emulsifier 5 g, oxyethylene / oxypropylene block polymer emulsifier 5 g, ion-exchanged water 170 g.

Next, in a 2-liter four-necked flask equipped with a stirrer, a cooler, a dropping funnel, a nitrogen suction tube, and a thermometer, 240 g of ion-exchanged water, 2 g of a 1: 1 mixture of the above emulsifier, and 0.8 g of potassium persulfate. Was charged, the temperature was raised to 70 ° C. while substituting with nitrogen, and then 1/6 of the emulsified monomer mixture liquid was added dropwise. When the reaction rate reached 90%, the remaining emulsified monomer mixture liquid was added dropwise over 2 hours for polymerization. After completion of dropping, the reaction was completed by aging at 70 ° C. for 2 hours.

After aging, the contents of the flask were cooled to 40 ° C,
An aqueous solution of potassium hydroxide was added to carry out a neutralization reaction, and after completion of the reaction, vigorous stirring was carried out to obtain a copolymer (2) used in the present invention. The obtained copolymer has a glass transition temperature of -29 ° C,
The gel fraction was 85%.

[Preparation of Undercoat Layer Coating Material] The undercoat layer coating material was prepared with the following composition to a concentration of 45%. 100 parts of the above copolymer (2), kaolin (trade name, Ultra White-90, manufactured by Engelhard) (average particle diameter: 0.4 μm)
m) 100 parts, talc (trade name, NK talc, manufactured by Chuo Kaolin Co., Ltd.) (average particle size: 8.0 μm) 20 parts,
1 part of lubricant (trade name, Nopcoat C-104, manufactured by Sun Nopco Co., Ltd.), defoaming agent (trade name, Nopco 1407)
K, manufactured by San Nopco Ltd.) 0.6 part.

[Formation of Undercoat Layer as Base Paper for Release Paper] Dry coating weight of 7 g / m ² with a rod blade coater was applied to high-quality paper having a basis weight of 50 g / m ² and a thickness of 65 μm.
Was coated and dried to obtain a base paper for release paper having an undercoat layer.

[Release Paper] A solvent-type silicone release agent (trade name, KS-3752, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the undercoat layer surface of the base paper for release paper with a bar coater at an amount of 0.9.
The release paper of the present invention was obtained by coating and heat-curing so as to have g / m ² .

[Adhesive Paper] An adhesive (trade name, Nicazole L-145, manufactured by Nippon Carbide Industry Co., Ltd.) was coated on the surface of the obtained release paper with a reverse roll coater so that the dry weight was 17 g / m ^2. After that, basis weight 64g / m ²
An adhesive sheet was obtained by pasting the same with high quality paper (trade name, TWF55, manufactured by Shin Oji Paper Co., Ltd.).

Example 6 In Example 1, the coating amount was 1. with a gravure coater in the same manner except that the release agent was solventless silicone (trade name, X-62-7200, manufactured by Shin-Etsu Chemical Co., Ltd.).
The release paper of the present invention was obtained by applying the solution so that the coating amount was 0 g / m ² and irradiating with an electron beam. An adhesive paper was manufactured in the same manner as in Example 1 using the obtained release paper.

Example 7 Preparation of Copolymer-2-Ethylhexyl Acrylate 7
Polymerization, neutralization with isopropyl alcohol and sodium hydroxide, etc. were performed in the same manner as in Example 1 except that a monomer mixture of 2 g, methacrylic acid 20 g, and acrylamide 8 g was used, and a water-soluble copolymer having a concentration of 30% was obtained. (3) was obtained. The obtained copolymer had a glass transition temperature of -29 ° C and a gel fraction of 70%.

[Preparation of Coating Material for Undercoat Layer] A coating material for undercoat layer was prepared to have a concentration of 40% with the following composition. 100 parts of the above-mentioned copolymer (3), wet heavy calcium carbonate (trade name, Hydrocurve K-9, manufactured by Bihoku Kouka Co., Ltd.) (average particle size: 0.6 μm) 100 parts, lubricant (commodity) Name, Nopcoat C-104, manufactured by San Nopco Co., Ltd. 1 part, antifoaming agent (trade name, Nopco 1407K, manufactured by San Nopco Co., Ltd.) 0.6 part.

[Formation of Undercoat Layer as Base Paper for Release Paper] A dry paper having a basis weight of 40 g / m ² and a thickness of 55 μm was coated with the above undercoat layer coating material with a rod blade coater to give a dry weight of 10 g / m 2.
^It was coated so as to be ² and dried to obtain a base paper for release paper provided with an undercoat layer.

[Release Paper] A solvent-free silicone release agent (trade name: KNS-320, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the undercoat layer surface of the base paper for release paper with a gravure coater at an application amount of 0.9 g / m 2. The release paper of the present invention was obtained by applying and heat-curing so as to be ² .

[Adhesive Paper] An adhesive (trade name, Nicazole L-145, manufactured by Nippon Carbide Industry Co., Ltd.) was coated on the surface of the obtained release paper with a reverse roll coater so that the dry weight was 17 g / m ^2. After that, basis weight 64g / m ²
An adhesive sheet was obtained by pasting the same with high quality paper (trade name, TWF55, manufactured by Shin Oji Paper Co., Ltd.).

Example 8 [Preparation of copolymer] Polymerization, deisopropyl alcohol and potassium hydroxide were carried out in the same manner as in Example 1 except that a monomer mixture of 60 g of butyl acrylate, 20 g of acrylic acid and 20 g of acrylonitrile was used. Neutralization reaction, etc.
A water-soluble copolymer (4) having a concentration of 30% was obtained. The obtained copolymer had a glass transition temperature of -12 ° C and a gel fraction of 60%.

[Preparation of Coating Material for Undercoat Layer] The coating material for undercoat layer was prepared to have a concentration of 45% with the following composition. 100 parts of the above copolymer (4), kaolin (trade name, Ultra White-90, manufactured by Engelhard) (average particle diameter: 0.4 μm)
m) 100 parts, talc (trade name, NK talc, manufactured by Chuo Kaolin Co., Ltd.) (average particle size: 8.0 μm) 20 parts,
1 part of lubricant (trade name, Nopcoat C-104, manufactured by Sun Nopco Co., Ltd.), defoaming agent (trade name, Nopco 1407)
K, manufactured by San Nopco Ltd.) 0.6 part.

[Formation of Undercoat Layer as Base Paper for Release Paper] A dry paper having a basis weight of 50 g / m ² and a thickness of 65 μm was coated with the above undercoat layer coating material with a rod blade coater to give a dry weight of 7 g / m ^2.
Was coated and dried to obtain a base paper for release paper having an undercoat layer.

[Release Paper] A solvent type silicone release agent (trade name, KS-3752, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the undercoat layer surface of the base paper for release paper with a bar coater at an application amount of 0.9.
The release paper of the present invention was obtained by coating and heat-curing so as to have g / m ² .

[Adhesive Paper] An adhesive (trade name, Nicazole L-145, manufactured by Nippon Carbide Industry Co., Ltd.) was coated on the surface of the obtained release paper with a reverse roll coater so that the dry weight was 17 g / m ^2. After that, basis weight 64g / m ²
An adhesive sheet was obtained by pasting the same with high quality paper (trade name, TWF55, manufactured by Shin Oji Paper Co., Ltd.).

Example 9 [Preparation of Copolymer] An emulsified monomer mixture liquid was prepared in the following formulation. 220 g of 2-ethylhexyl acrylate, 30 g of acrylic acid, 90 g of acrylonitrile, 60 g of methyl methacrylate, 8 g of polyexyethylenealkylphenylsulfate-based emulsifier, 8 g of sodium dioctylsulfosuccinate-based emulsifier, 170 g of ion-exchanged water.

Next, in a 2-liter four-necked flask equipped with a stirrer, a cooler, a dropping funnel, a nitrogen suction tube, and a thermometer, 240 g of ion-exchanged water, 2 g of a 1: 1 mixture of the above emulsifier, and 0.8 g of potassium persulfate. Was charged, the temperature was raised to 70 ° C. while substituting with nitrogen, and then 1/6 of the emulsified monomer mixture liquid was added dropwise. When the reaction rate reached 90%, the remaining emulsified monomer mixture liquid was added dropwise over 2 hours for polymerization. After completion of dropping, the reaction was completed by aging at 70 ° C. for 2 hours.

After aging, the contents of the flask were cooled to 40 ° C,
An aqueous potassium hydroxide solution was added to carry out a neutralization reaction, and after completion of the reaction, vigorous stirring was carried out to obtain a copolymer (5) used in the present invention. The obtained copolymer has a glass transition temperature of -15 ° C,
The gel fraction was 60%.

In Example 1, a copolymer for the above-mentioned copolymer (5) was used to prepare a coating material for an undercoat layer, and a base paper for release paper was obtained in the same manner as in Example 1, and Similarly, a release paper of the present invention was obtained. An adhesive paper was manufactured in the same manner as in Example 1 using the obtained release paper.

Example 10 [Preparation of Copolymer] An emulsified monomer mixture solution was prepared in the following formulation. Butyl acrylate 368g, acrylic acid 20
g, acrylonitrile 8 g, N-methylol acrylamide 4 g, polyethylethylene alkylphenyl sulphate emulsifier 8 g, sodium dioctyl sulfosuccinate emulsifier 8 g, ion-exchanged water 170 g.

Next, in a 2-liter four-necked flask equipped with a stirrer, a cooler, a dropping funnel, a nitrogen suction tube, and a thermometer, 240 g of ion-exchanged water, 2 g of a 1: 1 mixture of the above emulsifier, and 0.8 g of potassium persulfate. Was charged, the temperature was raised to 70 ° C. while substituting with nitrogen, and then 1/6 of the emulsified monomer mixture liquid was added dropwise. When the reaction rate reached 90%, the remaining emulsified monomer mixture liquid was added dropwise over 2 hours for polymerization. After completion of dropping, the reaction was completed by aging at 70 ° C. for 2 hours.

After aging, the contents of the flask were cooled to 40 ° C,
An aqueous potassium hydroxide solution was added to carry out a neutralization reaction, and after completion of the reaction, vigorous stirring was carried out to obtain a copolymer (6) used in the present invention. The obtained copolymer has a glass transition temperature of −48 ° C.,
The gel fraction was 55%.

In Example 8, a copolymer for the above-mentioned copolymer (6) was used to prepare a coating material for undercoat layer, and a base paper for release paper was obtained in the same manner as in Example 8, and Similarly, a release paper of the present invention was obtained. An adhesive paper was manufactured in the same manner as in Example 8 using the obtained release paper.

Comparative Example 1 [Preparation of paint for undercoat layer] A paint for undercoat layer was prepared to have a concentration of 23% with the following composition. Copolymer (1) 100 of Example 1
Parts, lubricant (trade name, Nopcoat C-104, manufactured by San Nopco Ltd.) 5 parts.

[Formation of Undercoat Layer as Base Paper for Release Paper] A dry weight of 7 g / m ² is obtained by using a bar coater and applying the above-mentioned undercoat layer coating to a high-quality paper having a basis weight of 50 g / m ² and a thickness of 65 μm. Thus coated and dried to obtain a base paper for release paper having an undercoat layer.

[Release Paper] A solvent type silicone release agent (trade name, KS-3752, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the undercoat layer surface of the base paper for release paper with a bar coater at an application amount of 0.9.
The release paper was obtained by coating and heat curing so as to be g / m ² .

[Adhesive Paper] An adhesive (trade name, Nicazole L-145, manufactured by Nippon Carbide Industry Co., Ltd.) was coated on the surface of the obtained release paper with a reverse roll coater so that the dry weight was 17 g / m ^2. After that, basis weight 64g / m ²
An adhesive sheet was obtained by pasting the same with high quality paper (trade name, TWF55, manufactured by Shin Oji Paper Co., Ltd.).

Comparative Example 2 A styrene-maleic acid copolymer having a concentration of 12% (trade name, script set 520, glass transition temperature 15) was used as a coating material for an undercoat layer on a high-quality paper having a basis weight of 50 g / m ² and a thickness of 65 μm.
6 ° C., gel fraction 85%, manufactured by Monsanto Co., Ltd.) was applied with a bar coater to a dry weight of 5 g / m ² and dried to obtain a base paper for release paper provided with an undercoat layer.

A solvent-type silicone release agent (trade name, LTC-350A, manufactured by Toray Dow Corning Silicone Co., Ltd.) was applied to the undercoat layer surface of the base paper for release paper and dried to obtain a release paper. An adhesive paper was manufactured in the same manner as in Example 1 using release paper.

Comparative Example 3 [Preparation of Copolymer] 120 g of isopropyl alcohol and 56 g of water were placed in a 1-liter four-necked flask equipped with a stirrer, cooler, dropping funnel, nitrogen suction tube and thermometer.
Is charged, and the temperature is raised to the reflux temperature under nitrogen flow and stirring.
Next, 60 g of butyl acrylate, 30 g of acrylic acid, 10 g of acrylonitrile, and 0.5 g of 2,2′-azobisisobutyronitrile were charged into the dropping funnel, and this uniform solution was added dropwise over 2 hours, and 2 hours after the completion of dropping. Aged.
The polymerization and aging are carried out at the reflux temperature, and after the aging,
The contents of the flask were cooled to 40 ° C., and a sodium hydroxide aqueous solution was added to carry out a neutralization reaction. After completion of the neutralization reaction, the temperature was raised to remove isopropyl alcohol from the system by azeotropic distillation with water, and after cooling, the concentration was diluted to 30% to obtain a copolymer (7). This copolymer has a glass transition temperature of -11.
C., gel fraction was 50%.

[Preparation of Coating Material for Undercoat Layer] The coating material for undercoat layer was prepared to have a concentration of 24% by the following composition. 80 parts of the above-mentioned copolymer (7), oxidized starch paste solution (trade name: Ace C, manufactured by Oji Cornstarch Co., Ltd.) 18 parts, colloidal silica (trade name, Snowtex 30, manufactured by Nissan Chemical Industries, Ltd.) (average) Particle diameter: 0.015 μ) 2 parts.

[Formation of Undercoat Layer as Base Paper for Release Paper] Dry coating weight of 7 g / m ² with bar coater of the above-mentioned coating material for undercoat layer on high-quality paper having a basis weight of 50 g / m ² and a thickness of 65 μm. Thus coated and dried to obtain a base paper for release paper having an undercoat layer. The paint for the undercoat layer was poor in dryness, and paper was frequently cut off, resulting in very poor productivity.

[Release Paper and Adhesive Paper] A solvent type silicone release agent (trade name, LTC-350) is applied to the undercoat layer surface of the release paper base paper.
A, manufactured by Toray Dow Corning Silicone Co., Ltd.) was applied and dried to obtain a release paper, and the obtained release paper was used to produce an adhesive paper in the same manner as in Example 1.

Comparative Example 4 [Preparation of Copolymer] 2 g of an anionic emulsifier (sodium lauryl sulfate), 0.5 g of ammonium persulfate and 125 g of ion-exchanged water were put in a reactor and heated with stirring.
While maintaining at 5 ° C., a mixture of 85 g of butyl acrylate, 7 g of methyl methacrylate, 5 g of acrylic acid and 3 g of methacrylic acid-β-hydroxyethyl was continuously added dropwise over 3 hours for polymerization. After completion of the dropping, the reaction was completed by aging at 75 ° C. for 3 hours to obtain a copolymer (8). The obtained copolymer had a glass transition temperature of −45 ° C. and a gel fraction of 45%.

[Preparation of Coating Material for Undercoat Layer] The coating material for undercoat layer was prepared to have a concentration of 25% with the following composition. 75 parts of the above copolymer (8), 25 parts of oxidized starch paste solution (trade name: Ace A, manufactured by Oji Corn Starch Co., Ltd.). This paint had poor stability and a tendency for starch to settle was observed.

[Formation of Undercoat Layer as Base Paper for Release Paper] Dry coating weight of 5 g / m ² with a bar coater was applied to a high quality paper having a basis weight of 50 g / m ² and a thickness of 65 μm. The base paper for release paper provided with an undercoat layer was coated and dried as described above, and streaks were observed on the surface of the base paper for release paper.

[Release Paper and Adhesive Paper] A solvent-free silicone release agent (trade name, BY24) is formed on the undercoat layer surface of the release paper base paper.
-456, Toray Dow Corning Silicone) was applied and heat-cured to obtain a release paper, and an adhesive paper was produced in the same manner as in Example 1 using the obtained release paper.

Comparative Example 5 A release paper and an adhesive paper were obtained in the same manner as in Example 1, except that low density polyethylene was laminated to a thickness of 20 μm by an extrusion laminating method instead of the undercoat layer.

Comparative Example 6 An adhesive paper was obtained in the same manner as in Example 1 using glassine paper (trade name, Separate 55GS, manufactured by Honshu Paper Co., Ltd.).

Comparative Example 7 A coating composition for an undercoat layer having a concentration of 25% was prepared in the same manner as in Example 1 except that the wet heavy calcium carbonate was changed to 30 parts. A release paper base paper was obtained in the same manner as in Example 1 below. An adhesive paper was manufactured in the same manner as in Example 1 using the obtained release paper.

Comparative Example 8 The procedure of Example 1 was repeated except that the wet heavy calcium carbonate was changed to 180 parts. A release paper base paper was obtained in the same manner as in Example 1 below. An adhesive paper was manufactured in the same manner as in Example 1 using the obtained release paper.

Comparative Example 9 [Preparation of Copolymer] 2 g of an anionic emulsifier (sodium lauryl sulfate), 0.5 g of ammonium persulfate and 125 g of ion-exchanged water were placed in a reactor and heated at 75 ° C. with stirring to keep the temperature at 75 ° C. , 2-ethylhexyl acrylate 95
g, acrylonitrile 3 g, and acrylic acid 2 g were continuously added dropwise over 3 hours to polymerize. After the dropping was completed, the reaction was completed by aging at 75 ° C. for 3 hours. After aging, the content of the reactor was cooled to 40 ° C., an aqueous solution of potassium hydroxide was added to carry out a neutralization reaction, and after completion of the reaction, strong stirring was carried out to obtain a copolymer (9). The obtained copolymer had a glass transition temperature of −63 ° C. and a gel fraction of 50%.

A concentration of 4 was obtained in the same manner as in Example 1 except that the copolymer (1) was changed to the copolymer (9).
A base paper for release paper was obtained in the same manner as in Example 1 by adjusting 0% undercoat layer paint, and release paper was obtained in the same manner as in Example 1 below. An adhesive paper was manufactured in the same manner as in Example 1 using the obtained release paper.

Comparative Example 10 [Preparation of Copolymer] An emulsified monomer mixture liquid was prepared with the following composition. Butyl acrylate 140 g, acrylonitrile 200 g, acrylic acid 50 g, N-methylol acrylamide 10 g, polyoxyethylene nonylphenyl ether emulsifier 5 g, oxyethylene / oxypropylene block polymer emulsifier 5 g, ion-exchanged water 170
g.

Next, in a 2-liter four-necked flask equipped with a stirrer, a cooler, a dropping funnel, a nitrogen suction tube, and a thermometer, 240 g of ion-exchanged water, 2 g of a 1: 1 mixture of the above emulsifier, and 0.8 g of potassium persulfate. Was charged, the temperature was raised to 70 ° C. while substituting with nitrogen, and then 1/6 of the emulsified monomer mixture liquid was added dropwise. When the reaction rate reached 90%, the remaining emulsified monomer mixture liquid was added dropwise over 2 hours for polymerization. After completion of dropping, the reaction was completed by aging at 70 ° C. for 2 hours.

After aging, the contents of the flask were cooled to 40 ° C,
An aqueous potassium hydroxide solution was added to carry out a neutralization reaction, and after completion of the reaction, vigorous stirring was carried out to obtain a copolymer (10). The obtained copolymer had a glass transition temperature of 27 ° C. and a gel fraction of 65%.

[Preparation of Coating Material for Undercoat Layer] The coating material for undercoat layer was prepared to have a concentration of 45% with the following composition. The above copolymer (1
0) 100 copies, Kaolin (trade name, Ultra White-
90, manufactured by Engelhard Co., Ltd. (average particle size: 0.4 μ)
m) 100 parts, talc (trade name, NK talc, manufactured by Chuo Kaolin Co., Ltd.) (average particle size: 8.0 μm) 20 parts,
1 part of lubricant (trade name, Nopcoat C-104, manufactured by Sun Nopco Co., Ltd.), defoaming agent (trade name, Nopco 1407)
K, manufactured by San Nopco Ltd.) 0.6 part.

[Formation of Undercoat Layer as Base Paper for Release Paper] Dry coating weight of 7 g / m ² is obtained with a bar coater using the above-mentioned coating material for undercoat layer on high-quality paper having a basis weight of 50 g / m ² and a thickness of 65 μm. Thus coated and dried to obtain a base paper for release paper having an undercoat layer.

[Release Paper] A solvent type silicone release agent (trade name, KS-3752, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the undercoat layer surface of the base paper for release paper with a bar coater at an application amount of 0.9.
The release paper was obtained by coating and heat curing so as to be g / m ² .

[Adhesive Paper] An adhesive (trade name, Nicazole L-145, manufactured by Nippon Carbide Industry Co., Ltd.) was coated on the surface of the obtained release paper with a reverse roll coater so that the dry weight was 17 g / m ^2. After that, basis weight 64g / m ²
An adhesive sheet was obtained by pasting the same with high quality paper (trade name, TWF55, manufactured by Shin Oji Paper Co., Ltd.).

The release paper and adhesive paper thus obtained were evaluated as follows, and the results are shown in Tables 1 and 2.

[Barrier Property] The release agent coating liquid was dropped onto the surface of the base paper for release paper, and its permeability was observed. ◯: Not penetrated Δ: Somewhat penetrated into the release paper base paper, but at a practically acceptable level X: Almost penetrated into the release paper base paper

[Blocking Property] The base paper for release paper is 5 cm.
Cut into 50 corners so that the undercoat layer and the base paper surface of the base paper come together.
After laminating the sheets and treating them at 50 ° C. and 95% RH for 7 hours, the degree of peeling was observed. ◯: It peels off cleanly Δ: There is some noise when peeling, but there is no problem in practical use X: It adheres and cannot be peeled off

[Peeling Force] When the high-quality paper having a basis weight of 64 g / m ² of the adhesive paper obtained in each example was peeled at an angle of 180 ° at a pulling speed of 300 mm / min by an Instron type tensile tester. The load (g / 50 mm) was measured.

[Curl] The curl of the pressure-sensitive adhesive paper obtained in each example was visually determined. ⊚: Flat ∘: Almost no curl Δ: Slightly curled, but no problem in practical use ×: Very curled, problematic level in practical use

[Suitability] Paper Copying Machine (Sharp SF-8
In 100), the passing state of the adhesive paper when the predetermined pattern was copied was observed. ◎: No paper jam occurs ○: Some paper jam occurs △: Some paper jam occurs and the adhesive paper slightly curls after copying, but it is not a problem for practical use ×: Frequent paper jam

[Appropriateness of Recycled Paper] 1 liter of 0.5% NaOH solution was added to 30 g of release paper, and 5000 rpm treatment was carried out by a TAPPI disintegrator.
Next, it was dehydrated to a concentration of 40%, further subjected to a kneading treatment, and then diluted to a concentration of 3% to prepare a handmade sheet, and the remaining state of undisaggregated substances was visually judged. 1 liter of a 0.5% NaOH solution was added to 30 g of release paper and the paper was processed by a TAPPI disintegrator for 5000 revolutions, and then a handmade sheet was prepared, and the remaining state of undisaggregated substances was visually judged. ◎: Almost no undissolved material ○: Undissolved material is slightly present, but there is no problem in practical use △: Undisaggregated material is slightly conspicuous and practically problematic ×: Undisaggregated material is noticeable

[Comprehensive Evaluation] The performance as the release paper of the present invention was evaluated by combining the above evaluations. ⊚: Very good performance ◯: Excellent performance Δ: Somewhat insufficient, but at a level where there is no practical problem ×: Insufficient, at a level that cannot be used

[0105]

[Table 1]

[0106]

[Table 2]

[0107]

As is apparent from the examples, the release paper of the present invention can be reused by the recycled pulp processing of used paper, and the curling can be effectively prevented, so that the release paper is suitable for passing in a copying machine. It was a release paper that can form an excellent adhesive paper.

Claims (3)

[Claims] 1. A release paper comprising an undercoat layer and a release agent layer laminated on at least one side of a base paper, wherein a copolymer having the following monomer composition is neutralized with an alkaline substance to obtain a water-soluble copolymer. And a copolymer having a glass transition temperature of −60 to 20 ° C. and a pigment as main components, and the pigment is 50 to 150 parts by weight with respect to 100 parts by weight of the solid content of the copolymer. Release paper characterized by (A) Ethylenically unsaturated carboxylic acid-containing monomer: 2 to 4
0 wt% (b) (meth) C ₄ -C ₁₀ alkyl ester monomers of acrylic acid: 50 to 90 wt% (c) these monomers and other copolymerizable monomers: 0
40% by weight 2. The release paper according to claim 1, wherein the pigment has an average particle diameter of 0.1 to 10 μm. 3. The release paper according to claim 1 or 2, wherein the film obtained by drying the copolymer has a gel fraction with respect to toluene of 55% by weight or more.