JPH1121796A - Release paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reusable base material for release paper, especially excellent in solvent barrier property, capable of directly applying a releasing agent such as silicone without requiring to laminate polyethylene film onto a raw paper and being stained by attachment to roll in drier process after coating, on-machine calender in finishing and super calender process and being stable in release force of the finished tacky sheet. SOLUTION: In release paper successively providing an undercoating layer and a releasing agent layer on at least one side of the base paper, the undercoating layer comprises a base material for releasing paper consisting essentially of a binder resin containing a pigment, polyvinyl alcohol and an aqueous emulsified copolymer (noion) having -50 to 20 deg.C Tg. The undercoating layer contains 30-500 pts.wt. polyvinyl alcohol and 10-100 pts.wt. aqueous emulsified copolymer based on 100 pts.wt. solid content of pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base material for release paper. More specifically, the present invention mainly relates to a base material of a release paper of an adhesive tape used for packing an adhesive label, an adhesive seal, a packaging container, and the like, which are attached to the surface of a product or a product container. More specifically, it has excellent solvent barrier properties, does not require the lamination of a polyethylene film on the base paper, can be directly coated with a release agent such as silicone, and has a drier process after coating, an on-machine calender and a super The present invention relates to a reusable release paper base material in which a peeling force of a finished pressure-sensitive adhesive sheet is stable without causing stains due to adhesion to a roll in a calendering step.

[0002]

2. Description of the Related Art Conventionally, a base material of a release paper has been used as a release agent or a release agent in order to improve the releasability of a label or a seal upper paper or the releasability of a tape wound in a cylindrical shape. For example, silicone is applied to form a release agent layer. As a base material of the release paper, papers such as a polyethylene laminate type, a glassine type, a super calendered type, and a clay coated type are known.

[0003] Among these base materials, the penetration of the above-mentioned silicone coating solution onto the surface of high quality paper, matte paper, kraft paper or the like made mainly of wood pulp is suppressed as much as possible, and the releasability is maximized. Extrusion method, thickness of 10
It is common to form a polyethylene film layer of about 25 microns. However, for the release paper substrate manufactured by the method of laminating the polyethylene film, the polyethylene film forms a strong continuous film, and since it is insoluble in water, the substrate is recovered,
Recycling in the papermaking process is not possible and presents a major problem in industrial waste disposal today.

On the other hand, a method has been attempted in which glassine paper or the like made of extremely beaten pulp is used as a base paper and silicone is directly coated without laminating a polyethylene film on the base paper. However, such base paper has a drawback that it is not easily dispersed in water because pulp as a raw material is extremely beaten and used, and furthermore, the bonding between fibers is strengthened by calendering or the like. Furthermore, even if it can be dispersed in water by strengthening the mechanical force and introducing chemical treatment, it is difficult to reuse it as a raw material for general paper because the fibers are significantly damaged by the strengthening of the beating treatment. is there.

[0005] In addition, even in a super calendered craft type substrate which has been densified by mechanical pressure, it is still impossible to completely close the minute voids, and further, when the silicone comes into contact, the substrate swells simultaneously. It is impossible to completely block permeation of a silicone organic solvent solution (hereinafter, referred to as solvent barrier property) which is comparable to the case where a polyethylene film is laminated.

On the other hand, JP-B-1-35959 and JP-A-4-23876 disclose base paper for a release paper obtained by directly applying silicone without laminating a polyethylene film. There is disclosed a clay coat type substrate in which a coating mainly composed of an inorganic pigment and an organic adhesive is applied to the surface to form an undercoat layer.
In such a base material, the effect of covering the minute voids (hereinafter referred to as pinholes) in the base paper with the undercoat layer is observed. However, the silicone penetrates into the base paper through numerous finer continuous pores that are innumerably present as fine voids between the pigments of the undercoat layer. For this reason,
In comparison with the method of laminating with a polyethylene film, a large amount of expensive silicone or undercoat layer must be coated.

[0007] The base paper for release paper manufactured in this manner has a problem in providing an undercoat layer. One of the problems is that the base paper is coated on the surface of a cylinder drier, a drier canvas, and a finishing machine such as a machine calender or a super calender. The phenomenon of dirt on which the layer adheres occurs. The occurrence of such stains not only causes a serious problem in operation, but also makes it impossible to obtain a satisfactory peeling force because the coating layer is detached.

In general, as a simple method of reducing the “friction” on the surface of an undercoat layer to prevent stains, calcium stearate, which is commercially available widely as a lubricant,
It is expected that zinc stearate-based, lecithin-based, carnauba wax-based and monostearylamine-ethylene oxide-based lubricants are blended in the coating liquid for the undercoat layer. However, when these lubricants were used, the slip of the undercoat layer was improved in any case, but the problem of solvent barrier property, which is the most important issue of the base material, was significantly reduced by the addition of the lubricant. Faced.

Although the cause of the decrease in the solvent barrier property is not clear, it is presumed that the blending of the lubricant inhibits the formation of the binder resin film in the undercoat layer. The formation of a film of the binder resin is based on hydrogen bonding of a hydroxyl group or a carboxylic acid group contained as a functional group in the molecule. For these negative groups, alkali metals,
It is presumed that a cationic group such as an alkaline earth metal or an emulsifier in a lubricant inhibits film formation and deteriorates solvent barrier properties.

For the above reasons, it has a solvent barrier property comparable to the case where a polyethylene film is laminated,
A release agent such as silicone can be applied directly, and a satisfactory release force can be obtained without causing dirt due to adhesion to rolls in the dryer process after coating, the machine calender during finishing, and the super calender process. Although there is a strong demand for a reusable release paper substrate, there has not yet been provided a method for producing a substrate capable of satisfying these requirements.

[0011]

DISCLOSURE OF THE INVENTION The present invention has an excellent solvent barrier property, does not require a polyethylene laminate, can directly apply silicone, and has a drier process after coating, a machine calender at the time of finishing, and a super It is an object of the present invention to provide a reusable release paper substrate having a stable release force without causing contamination due to adhesion to a roll in a calendering step.

[0012]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on the material of the undercoat layer formed on the base paper, and have finally found that a base material for release paper which can satisfy these requirements. I came to.

That is, the present invention relates to a release paper comprising a base paper and an undercoat layer and a release agent layer sequentially provided on at least one side of the base paper.
The undercoat layer contains a pigment and a binder resin as main components, and the binder resin contains at least polyvinyl alcohol and an aqueous emulsion copolymer, and the glass transition temperature of the aqueous emulsion copolymer is −50 to 20 ° C. Characteristic release paper base material. Further, the ionicity of the aqueous emulsion copolymer constituting the undercoat layer is nonionic, and polyvinyl alcohol is used in an amount of 30 to 100 parts by weight based on the solid content of the pigment.
It is characterized by containing 500 parts by weight and 10 to 100 parts by weight of an aqueous emulsion copolymer, and comprising pigment as kaolin.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have developed means for preventing the adhesion of a coating layer to a roll surface of a cylinder drier, a drier canvas, and a finishing machine such as a machine calender or a super calender after coating. In order to improve the "friction and instantaneous film formability" of the undercoat layer surface, an improvement method was studied.

By forming a barrier layer capable of simultaneously achieving (1) improving the film formability of the aqueous adhesive in the undercoat layer and (2) suppressing the formation of a film by the emulsifier in the lubricant, polyethylene is formed. Silicone can be applied directly without the need for lamination, and it is comparable to polyethylene laminate base material without causing stains due to adhesion to rolls in the dryer process after coating, machine calendering and super calendering processes after coating. It was concluded that this was an effective means of obtaining a substrate having a solvent barrier property.

As a result of further intensive studies to establish the above means, the present inventors have found that it is possible to simultaneously improve the film forming property of the binder resin in the undercoat layer and suppress the inhibition of film formation by the emulsifier in the lubricant. As a material, a pigment and a binder resin are main components, and the binder resin contains at least polyvinyl alcohol and an aqueous emulsion copolymer, and the glass transition temperature of the aqueous emulsion copolymer is -50 to 20 ° C, and the undercoat layer The ionicity of the aqueous emulsion copolymer constituting is nonionic, containing 30 to 500 parts by weight of polyvinyl alcohol and 10 to 100 parts by weight of the aqueous emulsion copolymer based on 100 parts by weight of the solid content of the pigment, And the pigment is
The inventors have found that kaolin exerts an excellent effect to satisfy the above requirements, and completed the present invention.

In the present invention, the aqueous emulsion copolymer constituting the undercoat layer has a very low glass transition temperature from the viewpoint of improving the film forming property of the binder resin in the undercoat layer and suppressing the inhibition of film formation by the emulsifier in the lubricant. is important. Incidentally, the glass transition temperature referred to in the present invention is measured by vibron viscoelasticity.

That is, if the glass transition temperature of the aqueous emulsion copolymer is low, the film-forming property is excellent, and there is no fouling due to adhesion to the roll in the drier step after coating and the machine calendering step in finishing.

That is, an aqueous emulsion copolymer having a low glass transition temperature and a pigment are instantaneously formed into a film, a pinhole on a substrate is caught, and then polyvinyl alcohol is used as a base material with excellent covering properties and a strong film. Suppresses permeation on the material, exhibits solvent barrier properties comparable to polyethylene laminate base, and does not cause stains due to adhesion to rolls in the dryer process after coating, machine calendering and super calendering processes during finishing Absent. However, if the glass transition temperature of the aqueous emulsion copolymer is high, the coating property on the base material and the film-forming property are poor, and the drying process after coating, the machine calender at the time of finishing and the super calendering process, It causes contamination due to adhesion.

Therefore, it is necessary to adjust the glass transition temperature of the aqueous emulsion copolymer so that the desired effects of the present invention are exhibited. The glass transition temperature of the specific aqueous emulsion copolymer used in the present invention is appropriately in the range of −50 to 20 ° C., and when the glass transition temperature is less than −50 ° C., the stability of the copolymer becomes insufficient. If the temperature exceeds 20 ° C., the film-forming property becomes insufficient. Therefore, the glass transition temperature of the aqueous emulsion copolymer needs to be in the range of −50 to 20 ° C. Further, the ionicity of the aqueous emulsion copolymer used in the present invention is not particularly limited and can be appropriately selected and used.However, from the viewpoint of suppressing the inhibition of film formation by the emulsifier in the lubricant and the stability of the coating liquid, Nonionic properties are preferred.

The aqueous emulsion copolymer used in the present invention contains 0.5 to 10% by weight of an emulsifier, and has the following composition: a) C4-18 alkyl ester monomer of (meth) acrylic acid: 30 B) ethylenically unsaturated carboxylic acid-containing monomer: 1 to 20% by weight
% By weight, c) Other monomers copolymerizable with these monomers: 0-3
0% by weight in the emulsion copolymerization.

The ethylenically unsaturated carboxylic acid-containing monomer constituting the specific aqueous emulsion copolymer used in the present invention includes, for example, acrylic acid, methacrylic acid,
Crotonic acid, maleic acid, itaconic acid, fumaric acid, monoalkyl fumaric acid and the like.

The proportion of these ethylenically unsaturated carboxylic acid-containing monomers in the copolymer is 1% by weight of all monomers.
When the content is less than 10, the dispersion stability of the obtained copolymer becomes insufficient, and when it exceeds 20% by weight, the drying property becomes insufficient. It is necessary to copolymerize in the range of 1 to 20% by weight.

On the other hand, the aqueous copolymer used in the present invention is
Constituting (meth) acrylic acid C_Four~ C₁₈Alkyl S
As the termonomer, for example, (meth) acrylate
, Hexyl (meth) acrylate, (meth) acrylic acid
Octyl, 2-ethylhexyl (meth) acrylate,
Lauryl (meth) acrylate, (meth) acrylate
Allyl and the like. These occupy in the copolymer
C of (meth) acrylic acid _Four~ C₁₈Alkyl ester simple substance
Body proportions are adjusted in the range of 30-90% by weight. 30
If it is less than 20% by weight, the glass transition temperature exceeds 20 ° C,
The desired effects of the present invention are not exhibited.

In the present invention, among these C ₄ -C ₁₈ alkyl ester monomers of (meth) acrylic acid,
Particularly, butyl acrylate and 2-ethylhexyl acrylate are preferably used from the viewpoint of copolymerizability and the like.

Other monomers copolymerizable with the above-mentioned monomers constituting the aqueous copolymer used in the present invention include, for example, methyl (meth) acrylate and (meth) acrylate.
Ethyl acrylate, propyl (meth) acrylate, vinyl acetate, vinyl chloride, vinylidene chloride, (meth) acrylonitrile, styrene, ethylene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, di (meth) acrylate Triethylene glycol acrylate, (poly) ethylene glycol (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, di (meth) acrylate
Acrylic acid (poly) propylene glycol, di (meth)
1,3-butylene glycol acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, divinylbenzene, 1,4-butanediol di (meth) acrylate, (meth) Glycidyl acrylate, methyl glycidyl (meth) acrylate, (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth)
Acrylamide, N, N'-methylenebis (meth) acrylamide and the like can be mentioned.

The proportion of these other copolymerizable monomers in the copolymer is adjusted in the range of 0 to 30% by weight.

In the present invention, among these copolymerizable other monomers, in particular, methyl (meth) acrylate,
(Meth) acrylonitrile, (meth) acrylamide and the like are preferably used from the viewpoints of glass transition temperature, solvent resistance, heat resistance and the like.

Examples of the chain transfer agent include thioglycerol, ethylene thioglycol, thioglycolic acid, n-dodecyl mercaptan and the like. Examples of the polymerization initiator include hydrogen peroxide, potassium persulfate, ammonium persulfate and the like. A so-called redox polymerization initiator comprising a combination of these with a reducing agent such as sodium zincate or sodium acid sulfite is exemplified.

The specific aqueous copolymers as described above are capable of converting a carboxyl group in the copolymer to a suitable one such as sodium hydroxide, potassium hydroxide, ammonia, various primary, secondary, and tertiary amines. It is stabilized by neutralization with an alkaline substance, and has a concentration of 20 to 60% by weight, preferably 30 to 60% by weight.
It is used after being adjusted to about 50% by weight.

The aqueous emulsion copolymer of the present invention is produced by a method of emulsion copolymerization in an aqueous system in the presence of an emulsifier, a chain transfer agent, a polymerization initiator and the like, and the type of the emulsifier is particularly important. That is, in the present invention, it is preferable to selectively use a nonionic emulsifier. As a specific example, for example,
Polyoxyethylene derivatives such as polyoxyethylene alkyl phenyl ether and polyoxyethylene sorbitan fatty acid ester, oxyethylene / oxypropylene /
Examples include block polymers, sorbitan fatty acid esters, and fatty acid monoglycerides.

Further, it is necessary to contain a pigment and polyvinyl alcohol as essential components. The amount of the aqueous emulsion copolymer to be used is 5 to 150 parts by weight, particularly preferably 10 to 100 parts by weight, per 100 parts by weight of the pigment. If the amount is less than 5 parts by weight, the effect of instantaneous film formation due to the combined use with polyvinyl alcohol is poor. If the amount exceeds 150 parts by weight, the effect of blocking pinholes is excellent, but the effect of preventing penetration is inferior. In addition, blocking and the like become a problem.

The pigment used in the undercoat layer in the present invention is not particularly limited, and may be suitably selected from pigments such as calcium carbonate, kaolin, talc, titanium oxide, and aluminum hydroxide. Kaolin, a plate-like pigment capable of forming a dense undercoat layer, is preferred from the viewpoint of properties.

The degree of saponification can be a partial saponification type or a complete saponification type, and the degree of polymerization is from 300 to 2500. Various modified polyvinyl alcohols such as carboxyl group-modified and acetoacetyl group-modified are used. Can also be used effectively. The number of parts to be used is 30 to 50 parts by weight per 100 parts by weight of the pigment.
When the amount is less than 30 parts by weight, the effect of preventing pinholes with respect to the solvent is high, but the effect of preventing penetration is poor. If it exceeds 500 parts by weight, the effect of preventing penetration is exhibited, but the effect of preventing pinholes is low. Furthermore, the adhesiveness of the film becomes too strong, and blocking and the like become a problem, which is not preferable.

The base paper used in the present invention is a chemical pulp such as bleached hardwood kraft pulp and bleached softwood kraft pulp.
Fine paper, medium quality paper, glazed paper and kraft paper made by using fourdrinier multi-cylinder paper machine, fourdrinier yankee paper machine or round mesh paper machine using mechanical pulp such as GP, RGP, TMP as raw material Etc., including acidic paper, medium-quality paper,
As the rice tsubo, one having 40 to 130 g / m ² is usually used. The base paper may contain papermaking auxiliary chemicals such as a paper strength agent, a sizing agent, a filler, and a retention aid.

These coating equipments, which are generally widely used, can be arbitrarily selected from a size press, a gate roll coater, a bar coater, a roll coater, an air knife coater and a blade coater. In consideration of the filling effect and the price of the paint, the barrier layer formed on the base paper is 2 to 20 g / m2 in absolute dry weight.
^It is desirable to prepare so that ^two coatings are applied.

The undercoat layer coating liquid of the present invention is an aqueous coating liquid containing a pigment and a binder resin as main components. If necessary, a dispersing agent, a coloring agent, a water-proofing agent, a lubricant and a preservative may be used. Etc. may be blended. The coating liquid for forming the undercoat layer may be applied to the base paper by two or more coating operations. Silicone is usually dissolved in an organic solvent such as toluene or hexane, or is not dissolved in an organic solvent or the like.
Coating is carried out by a solventless method with a 0% concentration. However, the undercoat layer according to the present invention can exhibit excellent barrier properties even in a method in which the coating liquid is cured by ultraviolet rays or electron beams.

Since the release paper using the base material of the present invention does not have a laminate layer of a release paper in which polyethylene is laminated and does not have silicone penetrating inside, it can be easily subjected to a regeneration step after recovery. That is, when put into water in the regeneration step, the undercoat layer separates from the base paper, so that only the pulp can be easily collected and reused. In addition, since the recycled pulp does not contain water-repellent silicone, the silicone does not enter the papermaking process of printing paper and the like, and does not cause trouble such as repelling.

[0039]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by these examples. In addition, the coating amount, the number of copies, the mixing ratio, and the like in the examples are all represented by solid contents. Further, “parts” indicates “parts by weight” unless otherwise specified.

Example 1 The coating liquid used was an undercoat layer having the following composition.
Coating was carried out on a high quality base paper of 80 g / m ^{2 by} a bar coater at a dry weight of 5 g / m ^2, and a coated paper having a moisture content of 5% after drying was obtained. Component Weight Kaolin (trademark: HT clay, manufactured by Engelhard) 100 parts Acrylic copolymer (trademark: Iodozol MR-96, manufactured by Kanebo NSC, glass transition temperature -15 ° C, ionicity: nonionic) 25 parts Polyvinyl alcohol (Trademark: PVA203, manufactured by Kuraray) 120 parts Oxidized modified starch (trademark: Oji Ace A, manufactured by Oji Constarch) 25 parts Ammonium stearate (trademark: Nopco DC-100-A, manufactured by San Nopco) 2 parts On the coated paper surface Silicone release agent (trade name: KS-8)
45, manufactured by Shin-Etsu Chemical Co., Ltd.) with a bar coater so as to have a dry weight of 0.9 g / m ² .
It was dried to give a release paper. An adhesive (trade name: AQ432T, manufactured by Kanebo NSC) on the surface of the release paper thus obtained.
Was coated with a reverse roll coater so as to have a dry weight of 17 g / m ² , and then adhered to a high quality paper (trade name: NWF55, manufactured by Oji Paper Co., Ltd.) of 64 g / m ^{2 in} rice tsubo to form an adhesive sheet. Obtained.

Example 2 In Example 1, polyvinyl alcohol (trade name: PVA) was used.
203, manufactured by Kuraray Co., Ltd.), and a coated paper was obtained in the same manner as in Example 1 except that the composition was changed to 400 parts. A solvent-free silicone release agent (trade name: KNS-320A, manufactured by Shin-Etsu Chemical Co., Ltd.) is applied on the coated paper surface with a gravure coater so as to have a dry weight of 0.9 g / m ^2, and thermally cured to release. Paper.
An adhesive (trade name: AQ4) is applied to the surface of the release paper thus obtained.
32T / Kanebo NSC) at a dry weight of 17 g / m
After coating with a reverse roll coater so that it becomes ² ,
The adhesive sheet was obtained by laminating with a high quality paper of 64 g / m ² (trade name: NWF55 / Oji Paper Co., Ltd.).

Example 3 In Example 1, polyvinyl alcohol (trade name: PVA) was used.
203, manufactured by Kuraray Co., Ltd.), and a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the composition was changed to 40 parts.

Example 4 The aqueous emulsion copolymer (1) prepared in Example 1 was mixed with 9
An adhesive sheet was obtained in the same manner as in Example 1 except that the composition was changed to 0 parts.

COMPARATIVE EXAMPLE 1 The coating liquid used was an undercoat layer having the following composition.
Same as Example 1 except that the coated paper was coated on a high quality base paper of 80 g / m ^{2 with} a gate roll coater so that the dry weight was 5 g / m ^2, and the coated paper having a moisture content of 5% after drying was obtained. To obtain a pressure-sensitive adhesive sheet. Component Weight Kaolin (trademark: HT clay, manufactured by Engelhard) 100 parts Acrylic copolymer (trademark: Iodozol MR-96, manufactured by Kanebo NSC Co., Ltd .; glass transition temperature -15 ° C, ionicity: nonionic) 25 parts

Comparative Example 2 The coating liquid used was an undercoat layer having the following composition.
Same as Example 1 except that the coated paper was coated on a high quality base paper of 80 g / m ^{2 with} a gate roll coater so that the dry weight was 5 g / m ^2, and the coated paper having a moisture content of 5% after drying was obtained. To obtain a pressure-sensitive adhesive sheet. Component weight Kaolin (trademark: HT clay, manufactured by Engelhard) 100 parts Polyvinyl alcohol (trademark: PVA203, manufactured by Kuraray) 75 parts

Comparative Example 3 The coating liquid used was an undercoat layer prepared in the following composition.
The same procedure as in Example 1 was carried out except that a coated paper having a water content of 5% after drying was obtained by coating with a bar coater on a high quality base paper of 80 g / m ^{2 in} a dry weight of 5 g / m ^2. To obtain an adhesive sheet. Component Weight Kaolin (trademark: HT clay, manufactured by Engelhard) 100 parts Aqueous emulsified copolymer (trademark: Newcoat EXP-0832, glass transition temperature 35 ° C, Shin-Nakamura Chemical Co., Ltd.) 25 parts Polyvinyl alcohol (trademark) PVA203, manufactured by Kuraray) 120 parts Oxidized modified starch (trademark: Oji Ace A, manufactured by Oji Constarch) 25 parts Ammonium stearate (trademark: Nopco DC-100-A, manufactured by San Nopco) 2 parts

Comparative Example 4 An adhesive sheet was obtained in the same manner as in Example 1 except that the coating liquid for the undercoat layer was changed to the following composition. Component Weight Kaolin (trademark: HT clay, manufactured by Engelhard) 100 parts Polyvinyl alcohol (trademark: PVA203, manufactured by Kuraray) 120 parts Oxidized modified starch (trademark: Oji Ace A, manufactured by Oji Constarch) 25 parts Ammonium stearate (trademark) : Nopco DC-100-A, manufactured by San Nopco) 5 parts

The effect of preventing the permeation of toluene, the effect of preventing pinholes, the effect of preventing silicone permeation, and the effect of reducing supercalender stain of the release paper substrates obtained in the above Examples and Comparative Examples were evaluated according to the following methods. . Table 1 shows the test results.

(1) Toluene permeation preventing effect and pinhole preventing effect: Oil-soluble dye "Olesol"
Toluene colored with "Red B" (manufactured by Sumitomo Chemical Co., Ltd.) was applied, and after 2 seconds, it was wiped off with a gauze, and the permeation state of toluene on the surface and the effect of pinholes occurring in spots were determined.

(2) Silicon Permeation Prevention Effect A silicone solution having the following composition was prepared. Component Weight Addition reaction type silicone (trademark: KS3752, manufactured by Shin-Etsu Chemical) 5.8 parts Platinum catalyst (trademark: CAT-PL-8, manufactured by Shin-Etsu Chemical) 0.2 parts Toluene 94 parts The above solution is placed on a paper piece. 1.0% dry by Meyer bar
g / m ^2, and the obtained surface was observed to evaluate the penetration of silicone.

(3) Supercalender stain improvement effect A 5000 m paper feed was applied at a linear pressure of 150 kg / cm and a speed of 10
Paper was passed through a super calender at 0 m / min and 70 ° C. to evaluate the degree of dirt on the chilled surface.

(4) Effect of Preventing Heavy Separation Load (g) when high-quality paper having a thickness of 64 g / m ² of adhesive sheet was peeled at an angle of 180 ° at a tensile speed of 300 mm / min by an Instron type tensile tester. / 50 mm).

[0053]

[Table 1]

As is clear from Table 1, the release paper substrates of Examples 1 to 4 according to the present invention each obtained satisfactory results, but the release paper substrates of Comparative Examples 1 to 4 Was unsatisfactory in any of the properties.

[0055]

The base material for release paper of the present invention has excellent solvent barrier properties comparable to the base material for release paper to which a polyethylene film has been bonded, and the existing paper machine and coating machine. Can be easily manufactured, and can be reused after collection, and are extremely excellent in practicality.

Claims (4)

[Claims] 1. A release paper comprising a base paper and an undercoat layer and a release agent layer sequentially provided on at least one side of the base paper, wherein the undercoat layer comprises a pigment and a binder resin as main components, and the binder resin comprises at least polyvinyl alcohol and an aqueous emulsion. A base material for release paper, comprising a polymer, wherein the aqueous emulsion copolymer has a glass transition temperature of -50 to 20C. 2. The release paper substrate according to claim 1, wherein the ionicity of the aqueous emulsion copolymer constituting the undercoat layer is nonionic. 3. The release paper according to claim 1, wherein the undercoat layer contains 30 to 500 parts by weight of polyvinyl alcohol and 10 to 100 parts by weight of an aqueous emulsion copolymer based on 100 parts by weight of the solid content of the pigment. Base material. 4. The release paper substrate according to claim 1, wherein the pigment constituting the undercoat layer is kaolin.