JPH10131098A - Base paper for separate paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a base paper for a separate paper hardly having unevenness of the surface coated with a stripping agent and further hardly imparting an unevenness to a surface substrate laminated thereon. SOLUTION: This base paper for a separate paper has a stripping agent layer and an adhesive agent layer arranged in order so that a film may be laminated through the adhesive layer, and the surface of the base paper opposite to the surface for coating the adhesive layer has 5-20g/m<2> water absorbing capacity measured in the condition of 5sec water absorbing period regulated by JIS P8140 (a cup method), and <=3.5 formation coefficient F shown by the formula F=(D2 /D1 )×100(D1 is an average concentration of shadowgram by an transmitted light in the total of KSK formation of the base paper for a separate paper; D2 is a standard deviation of the concentration of the shadowgram).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base paper for release paper which becomes a release paper for an adhesive product such as an adhesive label by applying a release agent. The present invention relates to a base paper for release paper, which reduces irregularities of the coated surface and the surface substrate.

[0002]

2. Description of the Related Art Conventionally, adhesive sheets have been used for labels, seals,
It is used for a wide range of applications such as commercial use, office use, and home use, such as stickers, patches, and overlamps. This pressure-sensitive adhesive sheet is generally formed by laminating a surface substrate, a pressure-sensitive adhesive, and a release paper. As the pressure-sensitive adhesive, a solvent-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, a hot-melt-type pressure-sensitive adhesive, or the like is used.

[0003] Surface base materials include high-quality paper, kraft paper, art paper, coated paper, cast coated paper, general papers such as heat-sensitive recording paper, aluminum foil lamination paper, aluminum-deposited paper, resin-impregnated paper,
Special papers such as synthetic paper, and films such as PET, polypropylene, and polyvinyl chloride are used. Among these, films are used for adhesive sheets for overlaminating and outdoor use because they have higher durability than papers for other surface base materials, and they have a very high gloss, because they have extremely high gloss. Used for certain adhesive sheets.

On the other hand, release paper is preferably made of polyethylene laminate type, glassine type, clay coat type, water-based resin coat, etc. in order to improve the releasability from the surface substrate such as adhesive labels and adhesive tapes. A type and a film base type and a combination thereof, for example, a product obtained by laminating a glassine paper with polyethylene are known. A release agent, that is, a solvent-type, emulsion-type, or solvent-free type coating agent such as a silicone resin, a fluorine resin, an amino alkyd resin, or a polyester resin is applied to these base materials to obtain release paper.

[0005] In particular, a polyethylene laminate type release paper is often used for an adhesive sheet using a film as a surface substrate. This is because the surface substrate is a film,
Although there is no dimensional change due to the humidity change, since the release paper is paper, the dimensional change accompanying the humidity change is remarkable. As a result, the dimensional change between the surface substrate and the release paper is different, so that the curling of the pressure-sensitive adhesive sheet due to the humidity change becomes a problem.

In order to suppress the curl, the back surface of the release paper is subjected to a water treatment before or after laminating the surface base material to correct the curl. For this reason, when such a configuration method is adopted, the finished product may show unevenness of the surface substrate.

The base paper for release paper is usually finished to be highly smooth in order to obtain a uniform coated surface of the release agent. In particular, some glassine paper has a Beck smoothness of several thousand seconds. However, even if the smoothness was improved and the releasability was improved, the roughness of the release agent-coated surface and the surface substrate could not be said to be improved.

[0008] The "bumpiness" referred to herein refers to the unevenness of the surface base material that is visible, and does not particularly limit the pattern, the height difference of the unevenness, the distance of the unevenness, and the like. Adhesive products using this release paper not only have poor appearance after printing and printed products, but also when adhered to non-breathable adherends such as glass, metal, and plastic solids, This causes air to enter the surface of the pressure-sensitive adhesive sheet, giving rise to unevenness of the surface of the pressure-sensitive adhesive sheet, which makes it difficult to obtain a high-quality pressure-sensitive adhesive sheet.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a base paper for a release paper, which has less unevenness on the surface coated with a release agent and further has less unevenness on a surface substrate bonded thereto.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems, and as a result, the occurrence of unevenness on the surface of the pressure-sensitive adhesive sheet has been observed, particularly, the formation unevenness of the base paper for release paper and the back surface of release paper. Due to the absorption of water from the, by setting the water absorption from the back of the release paper and the formation coefficient within a predetermined range,
The present inventors have found that an excellent pressure-sensitive adhesive sheet free of unevenness on the surface of the pressure-sensitive adhesive sheet and full of high-grade feeling can be obtained, and completed the present invention.

That is, in the present invention, a release agent for a base paper for a release paper is applied to a base paper for a release paper of a pressure-sensitive adhesive sheet in which a release agent layer and a pressure-sensitive adhesive layer are sequentially provided and a film is bonded via the pressure-sensitive adhesive layer. The surface opposite to the surface has a water absorption of 5 to 20 g / m ² measured under the condition of water absorption time of 5 seconds (Cobb method) specified in JIS P8140, and a formation coefficient of the base paper for release paper. Is 3.5 or less.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention described the cause of the unevenness of the surface of the pressure-sensitive adhesive sheet which occurred when a film was used as the surface substrate, in various angles such as the surface substrate, the pressure-sensitive adhesive layer, and the release sheet. From the research.

As a result, the present inventor has found that the formation unevenness of the wavelength of 2 to 10 mm of the base paper for the release paper used as the release paper matches the unevenness of the surface of the pressure-sensitive adhesive sheet. That is, due to uneven formation of the base paper for the release paper used as the base paper, unevenness occurs on the surface of the release paper itself, and the film of the surface base material promotes the unevenness, and unevenness on the surface of the adhesive sheet and It was found that gloss unevenness was caused.

When a release paper using a high quality paper, a kraft paper or a glassine paper as a base paper having a formation unevenness of a wavelength of 2 to 10 mm is used, the release paper may be a glassine type, a polyethylene type, a clay coat type, Regardless of the water-based resin coat type, it was found that the surface of the pressure-sensitive adhesive sheet was uneven.

This phenomenon is promoted by the processing steps described below. That is, in the production process of the normal pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet in which the release paper and the film are bonded via the pressure-sensitive adhesive has a curl with the film surface inside at the outlet of the dryer. Such curling not only lowers the quality value of the pressure-sensitive adhesive sheet, but also becomes a fatal defect such as difficulty in passing the paper when printing is performed. For this reason, the pressure-sensitive adhesive sheet that has exited the dryer is generally subjected to steam humidification or gravure roll watering treatment on the backside of the release paper for the purpose of correcting the curl of the pressure-sensitive adhesive sheet after laminating the film. is there.

At the time of this watering treatment, water is absorbed by the back surface of the release paper, and the curl can be corrected by absorbing the water.
Due to this, when the formation unevenness of the base paper for release paper is remarkable,
There is a dense and dense portion of the fiber distribution, and due to the absorption of water, the dense portion has a large fiber swelling, and the thin portion has a small fiber swelling, which causes minute thickness unevenness in the base paper for release paper. The thickness unevenness causes unevenness on the surface of the release paper, and the surface substrate film having a high gloss promotes the unevenness and causes unevenness on the surface of the pressure-sensitive adhesive sheet.

Even if the base paper for release paper has a non-uniform formation, if the amount of water absorption that permeates from the back surface is small, the swelling of the dense and sparse portions of the fibers is reduced by that amount, resulting in uneven thickness of the base paper for release paper. However, if the water application amount is small, the curl correcting effect of the pressure-sensitive adhesive sheet is small, and the desired curl correction cannot be achieved.

On the other hand, in the case of a release paper using a base paper of a release paper having a good formation as a base paper, the unevenness and gloss unevenness of the pressure-sensitive adhesive sheet do not occur, as compared with a release paper base paper having a non-uniform formation.
Since the formation is good, the difference between the coarse and dense portions of the fibers is small, and the difference in the swelling of the fibers due to the absorption of moisture from the back surface is small.

Further, the water absorption behavior of the back side of the base paper for release paper is
J. TAPPI paper pulp test method No. K.13-77. B. B. Sizing degree, J. TAPPI paper pulp test method No. Measured by various water absorption test methods such as pen writing size specified in 12-76 and Steckigt size specified in JIS P8122, and the relationship between these measured values and unevenness on the surface of the adhesive sheet was examined in detail. As a result of the analysis, the back surface of the release paper was JIS P8140
Measured under the condition of 5 seconds water absorption specified in (Cobb method)
And found that the measured value by this method was in the range of 5 to ²⁰ g / m ² , and it was concluded that the generation of unevenness on the surface of the pressure-sensitive adhesive sheet could be prevented.

If the measured value of the water absorption measured under the condition (Cobb method) of 5 seconds under the condition of JIS P8140 of 5 seconds is less than 5 g / m ² , the water absorption of the back surface of the base paper for release paper is insufficient. However, by the usual steam humidification or watering treatment using a gravure roll or the like, it is not possible to obtain a water amount necessary for the curl correction on the back surface of the release paper, and the curl cannot be corrected.

When the measured value of the water absorption measured under the condition of the water absorption time of 5 seconds (Cobb method) is larger than 20 g / m ² , the water absorption speed is too fast to promote an uneven water absorption distribution,
A distorted dimensional change occurs, resulting in unevenness on the surface of the release paper, resulting in unevenness on the surface of the pressure-sensitive adhesive sheet on which the surface substrate film having high gloss is laminated.

The water absorbency measured by the Cobb method of the present invention is a measure of the water absorbency when one side of paper and paperboard is in contact with water for a certain period of time specified in JIS P8140. In general, the measurement is made on the basis of 120 seconds, but it can be measured by changing as necessary.

The present inventors caused scattering of light on the surface of the pressure-sensitive adhesive sheet, and as a result, the roughness of the surface of the pressure-sensitive adhesive sheet having a wavelength of 2 to 10 mm was measured particularly under the condition of a water absorption time of 5 seconds. They found that there was a high correlation with the water absorption.

The reason why the contact time with water, that is, the water absorption time is as short as 5 seconds, is considered to be that the unevenness of the pressure-sensitive adhesive sheet is caused by a very short time of water absorption after the pressure-sensitive adhesive sheet is manufactured.

Further, the condition for further shortening the contact time is that this method fixes a metal ring on paper, adds water to the metal ring, removes the water after a predetermined time, and removes the water. Is a method of measuring the weight by wiping the surface with the method, so that many measurement errors occur.
As a result, the correlation with the unevenness of the wavelength of 10 to 10 mm becomes low.

In the present invention, the back surface of the base paper for release paper is
In order to obtain a base paper for release paper having a water absorption of 5 to 20 g / m ² measured under the condition of 5 seconds water absorption (Cobb method) specified in JIS P8140, wood pulp is used as a main raw material. In paper stock prepared by compounding various chemicals such as dyes and adhesives as necessary, the internal size represented by rosin-based sizing agents, petroleum resin-based sizing agents, and other synthetic sizing agents It can be obtained by appropriately setting the type and amount of the agent.

Also, a desired water absorption can be obtained by adding a surface sizing agent represented by a polystyrene / maleic acid copolymer resin or a polystyrene / acrylic copolymer resin.

Although examples of the means for obtaining the desired degree of water absorption have been described above, the invention is not limited to these means.
As a result, if the back surface of the release paper has a water absorption of 5 to ²⁰ g / m ² measured (Cobb method) under the condition of a water absorption time of 5 seconds specified in JIS P8140, a criticality in the quality of the adhesive sheet is obtained. The unevenness on the surface of the pressure-sensitive adhesive sheet, which is a target defect, can be eliminated.

As a tester for measuring the formation of paper, a 3-D sheet analyzer (manufactured by M / K SYSTEM Inc), a formation analyzer (manufactured by Kayani), and an FMT-10, which use white light as a light source, are used.
00 (manufactured by Nomura Corporation), a sheet formation analyzer (manufactured by Toyo Seiki), an F sensor (manufactured by Aikawa Iron Works) and the like using He-Ne laser light are known.

These have different measurement spot sizes, measurement areas, measurement intervals, measurement data numbers, and the like, and a certain degree of correlation can be obtained. However, one having a good formation coefficient is necessarily good on the other. Not necessarily.

The present inventor examined the relationship between the formation observed by the human eye and the numerical values obtained by various formation test machines, and found that the formation coefficient obtained by the KSK ground total (manufactured by Kanzaki Paper) was particularly visible. We found that there was a correlation with formation. The measurement principle of the KSK ground total is that a daylight fluorescent lamp is used as a light source and the sample measurement area is 1
The shadow image density due to the transmitted light of 0 × 10 cm ² is divided and measured by a CCD camera into fine dots, and the formation coefficient FF = () having the following formula relationship with respect to the average shadow image density D ₁ and the shadow image density standard deviation D _2. D ₂ / D ₁ ) × 100.

Further, in the ground sum used in the present invention, usually,
The measurement area was 100 cm ² , and the size of the measurement spot was 0.1 cm.
Although the measurement is performed at 2 mm × 0.2 mm, the measurement area and the size of the measurement spot are not limited. However, if the measurement area is too small, the correlation with visual formation decreases, so the measurement area is preferably 10 cm ² or more.
In addition, in order to obtain the correlation between the size of the measurement spot and the formation by visual observation, it is necessary to use 0.02 mm × 0.02 mm to 2.0 mm ×
2.0 mm is preferred.

The formation of the paper is defined as the uniformity of the state in which the fibers are distributed in the paper, and indicates the density of the sheet, that is, the degree of local unevenness of the basis weight, thickness, and tension. . Many formation testing machines are manufactured based on the fact that there is a correlation between the change in the amount of transmitted light and the change in the basis weight. However, a ground sum having a high correlation between the visual formation and the formation coefficient based on the total ground has not been found so far. However, it has been confirmed that the KSK ground total in the present invention has a high correlation with the visual formation. The inventors have found and completed the present invention.

The smaller the numerical value of the formation coefficient based on the KSK ground sum in the present invention, the better the formation.

The formation coefficient of the present invention is characterized in that it is 3.5 or less. If it exceeds 3.5, however, the distribution unevenness of the fibers in the base paper for release paper becomes remarkable, and the density of the fibers is reduced. Exists, and even if it does not absorb moisture, the formation is poor and bumps occur. Also, if you absorb moisture,
The swelling of the fiber increases, the unevenness in the thickness of the sparse and dense portions of the fiber increases, and the unevenness increases.

Even if the formation coefficient is 3.5 or less, the water absorption measured under the condition of the water absorption time of 5 seconds is 20 g /
If it exceeds m ² , the absolute amount of swelling of the fiber increases, causing unevenness in thickness, and the unevenness worsens. On the other hand, if the formation coefficient is 3.5 or less and the water absorption is less than 5 g / m ² , swelling due to fiber swelling does not occur, but the water absorption required is small because the water absorption is small. The curl correction cannot be performed.

The formation coefficient of the base paper is controlled as follows.
For example, pulp composition of base paper, beating conditions, type and amount of filler, paper strength agent, filling sizing agent, pH, surface sizing agent, surface treatment agent, papermaking concentration, forming board position, wire mesh, hydrofoil arrangement, papermaking Jet /
Achieved by appropriately adjusting various conditions such as wire ratio, wire shaking, paper filler distribution, dandy roll use conditions, smoother press conditions, press press conditions, press draw conditions, drying temperature conditions, and super calender conditions. You. These cannot be described as generalized numerical conditions because the installation conditions, design conditions, and equipment conditions of individual paper machines are different.

The base paper used in the present invention includes chemical pulp such as hardwood bleached kraft pulp, softwood bleached kraft pulp, hardwood sulphite pulp, softwood sulphite pulp, and mechanical pulp such as GP, RGP, TMP and CTMP.
Fine paper made from semi-chemical pulp such as SCP or CGP or deinked waste paper pulp as a raw material and made by Fourdrinier multi-cylinder paper machine, Fourdrinier Yankee type paper machine, Twin wire paper machine or Round mesh paper machine , Neutral paper, neutral paper, alkaline paper, and the like. Further, the base paper thus formed may be subjected to a surface sizing treatment of an aqueous resin aqueous solution such as polyvinyl alcohol in a coating unit such as a size press device or a gate roll coating machine.

The basis weight of the base paper for release paper in the present invention is 30.
It is desirably ^{g / m 2 ~130g / m 2} . By the way, if it is less than 30 g / m ² , since the amount of transmitted light is large as a whole, the formation coefficient does not match with the formation as seen by eyes, and as a result, the correlation with the bumpiness may not match. On the other hand, if it is larger than 130 g / m ² , on the contrary, the transmitted light amount is too small, and there is a possibility that the correlation between the formation coefficient and the unevenness may be lost.

The base paper for release paper in the present invention may be coated with a barrier agent on the surface to which the release agent is applied before applying the release agent. The barrier agent is applied to prevent the penetration of the solvent of the solvent-based release agent, for example, polyvinyl alcohol,
Using aqueous resins such as denatured polyvinyl alcohol, polyvinylpyrrolidone, polyethyleneimine, polyacrylate, starches, cellulose derivatives, urethane resins, acrylic resins, polyester resins, alkyd resins, and melamine resins, for example, air knife coaters and roll coaters , Reverse roll coater, blade coater, bar coater, curtain coater, die slot coater,
It is coated and dried on a base paper for release paper by an on-machine or off-machine coater equipped with a suitable coating device such as a gravure coater, a chaplex coater, a brush coater, a gate roll coater, and a size press coater.

In the base paper for release paper in the present invention, an ethylene resin may be laminated on the surface to which the release agent is applied before applying the release agent. As the ethylene-based resin, all of a homopolymer of ethylene and a copolymer mainly composed of ethylene can be used. Specifically, as those produced by a high-pressure method, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer can be used. Coalescence, ethylene- (meth) acrylic acid ester copolymer, ethylene- (meth) acrylic acid copolymer,
And ionomers thereof, and ethylene-propylene copolymers produced by a medium-to-low pressure method,
Linear low-density polyethylene such as ethylene-1-butene copolymer and the like can be mentioned. However, it is not limited to these.

Extrusion lamination, film lamination, and the like are suitable as a method of laminating an ethylene-based resin. An adhesive is used on the surface of the base paper for release paper to be adhered to the polyethylene laminate layer in order to improve the adhesion. Coating, ozone treatment, or corona discharge treatment may be applied.

Further, the base paper for release paper in the present invention may be clay-coated on the surface coated with the release agent before coating the release agent. Clay coat layer is calcium carbonate, kaolin, aluminum hydroxide, titanium oxide, talc, satin white, barium sulfate, zinc oxide, acid clay, inorganic pigments such as silica, polypropylene resin, polyethylene resin, styrene resin, acrylic-styrene resin, Urea formalin resin, melamine-
Pigments such as organic pigments such as formalin resin and benzoguanamine resin and water-soluble adhesives such as polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylate, oxidized modified starch, phosphate modified starch, carboxymethylcellulose, hydroxyethylcellulose, etc. Butadiene copolymer latex, acrylic latex, acrylonitrile-butadiene copolymer latex, a paint mainly containing an adhesive such as a synthetic resin latex such as urethane latex, for example, an air knife coater, a roll coater, a reverse roll coater, a blade coater , Bar coater, curtain coater, die slot coater, gravure coater, champlex coater, brush coater, gate roll coater,
It is formed by coating and drying on base paper for release paper using an on-machine or off-machine coater equipped with a suitable coating device such as a size press coater.

As the release agent used in the present invention, an emulsion type, a solvent type, or a non-solvent type silicone resin, a fluorine resin, an amino alkyd resin, a polyester resin and the like are used. As a method of applying these release agents, a bar coater, a multi-stage roll coater, a gravure coater, or the like is appropriately used. The coating amount is not particularly limited, but is 0.3 g / m ^{2 in} solid content.
３3.0 g / m ² , preferably 0.5 g / m ² １．５1.5
It is adjusted in the range of g / m ² .

Examples of the pressure-sensitive adhesive include natural rubber, styrene-butadiene copolymer, styrene-isoprene copolymer, chloroprene rubber, butyl rubber, polyisobutylene, ethylene-vinyl acetate copolymer, recycled rubber, synthetic rubber and the like. A pressure-sensitive adhesive such as an acrylic, an acrylic, or a silicone is appropriately used. These pressure-sensitive adhesives are in the form of a solvent system, an aqueous emulsion system, a hot melt system, a liquid curable type and the like, for example, a knife coater, a roll coater, a die coater,
It is applied by a comma coater, gravure coater, screen printing or the like. The coating amount is not particularly limited, but is 10 to 40 g / m ² by dry weight, preferably 1 to
It is adjusted in the range of about 3 to 28 g / m ² .

As described above, the inventors of the present invention have found that the occurrence of unevenness on the surface of the pressure-sensitive adhesive sheet is caused particularly by the water absorption from the back side of the base paper for release paper and the formation of the base paper for release paper. By setting the formation of the base paper for release paper within a predetermined range, it has been found that a pressure-sensitive adhesive sheet free of unevenness on the surface of the pressure-sensitive adhesive sheet can be obtained.

[0047]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted thereto. In each example, "part" and "%"
Means "part by weight of solid content" and "% by weight of solid content", respectively, unless otherwise specified.

Example 1 [Production of base paper for release paper] First, a stock having the following composition was prepared. -Degree of beating: 30 parts of 450 ml CSF (softwood kraft pulp)-Degree of beating: 70 parts of 350 ml CSF (hardwood kraft pulp)-30% reinforced rosin sizing agent (trade name: SPE, Arakawa Chemical Industries) 1.2 parts-30% sulfuric acid Aluminum 2 parts Note) CSF: Canadian standard freeness, conforming to JIS P8121. same as below

This paper stock was diluted to 0.75%, a base paper having a basis weight of 73 g / m ^{2 was formed with} a fourdrinier multi-cylinder paper machine, dried, and then dried with a size press machine installed in the paper machine. A 5% aqueous solution of an alcohol-based resin (trade name: NH20, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was applied and dried again. The coating amount at this time was 1.2 g / m ² . The formation coefficient at this time was 3.2, and the water absorption measured under the condition of 5 seconds water absorption specified in JIS P8140 on the back was 1
It was 2.8 g / m ² .

Then, polyvinyl alcohol (trade name:
120 parts of PVA117, manufactured by Kuraray Co., Ltd. and 100 parts of kaolin (trade name: HT clay, manufactured by Engelhard Co.) are mixed with a coating material on a surface to be coated with a release agent, in an amount of 5 g / m ^2.
It was coated with a blade coater and finished with a super calendar.

[Production of release paper] A silicone solution having the following composition was prepared. -Addition reaction type silicone (trade name: SD7220, manufactured by Toray) 4.5 parts-Platinum catalyst (trade name: SRX212, manufactured by Toray) 0.5 parts-Toluene 95 parts The obtained base paper for release paper was obtained. The obtained solution was applied using a Meyer bar so that the weight after drying was 2.0 g / m ² , to obtain a release paper.

[Production of pressure-sensitive adhesive sheet] An acrylic solvent-type pressure-sensitive adhesive (trade name: Nissetsu KP-1954,
100 parts of Nippon Carbide Co., Ltd., and 1.5 parts of a curing agent (trade name: Nissetsu D-201, Nippon Carbide Co.) were coated and dried with a reverse roll coater so that the coating amount was 25 g / m ^2. After that, aluminum evaporated PET as surface substrate
(Product name: MSN # 25, manufactured by Toray)
Further, a gravure coater was used on the surface opposite to the surface base material so that the curl of the pressure-sensitive adhesive sheet was flat to obtain a pressure-sensitive adhesive sheet.

Example 2 In the production of the base paper for release paper of Example 1, polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.) 120
Parts, and 100 parts of kaolin (trade name: HT clay, manufactured by Engelhard Co.) are mixed, and a low-density polyethylene is applied by melt extrusion coating so that the film thickness becomes 25 μm. A release paper and an adhesive sheet were obtained in the same manner as in Example 1, except that the temperature was changed to lamination at 330 ° C. The formation coefficient of the obtained base paper for release paper was 3.2, and the water absorbency measured under the condition of a water absorption time of 5 seconds was 1
It was 2.8 g / m ² .

Example 3 In the production of the base paper for release paper of Example 1, the stock was adjusted as follows and the papermaking conditions were as follows: the papermaking density was 0.7%, the forming board position, and the coarseness of the wire mesh. Now, hydrofoil arrangement, Jet / Wire ratio,
A release paper and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1, except that the conditions for using wire shaking and dandy rolls were slightly changed.

Composition of paper material-Beating degree: 300 ml CSF (softwood kraft pulp) 60 parts-Beating degree: 280 ml CSF (hardwood kraft pulp) 40 parts-30% reinforced rosin sizing agent (trade name: SPE, manufactured by Arakawa Chemical Industries) 2 3.0 parts 30% aluminum sulfate 3 parts The water absorption of the back surface of the base paper for release paper manufactured by the above method was measured (Cobb method) under the condition of a water absorption time of 5 seconds (9.2).
g / m ² and formation coefficient were 2.8.

Example 4 In the manufacture of the base paper for release paper of Example 1, after drying, 100 parts of a polyvinyl alcohol-based resin (trade name: NH20, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) (Trade name: Polymer Set 305, manufactured by Arakawa Chemical Industry Co., Ltd.) A release paper and an adhesive sheet were obtained in the same manner as in Example 1 except that a 3% aqueous solution containing 3 parts was applied. The formation coefficient of the obtained base paper for release paper was 3.2,
The water absorption measured under the condition of a water absorption time of 5 seconds is 18.2 g / m.
^{Was 2} .

Example 5 In the production of the base paper for release paper of Example 1, a styrene-butadiene copolymer latex (Polylac 750K-101, manufactured by Mitsui Toatsu Co., Ltd.) was applied to the surface opposite to the surface to which the release agent was applied. Was applied using a Meyer bar so that the coating amount was 2 g / m ² to obtain a release paper and an adhesive sheet in the same manner as in Example 1. In addition, the formation coefficient of the obtained base paper for release paper was 3.2, and the water absorption measured under the condition of a water absorption time of 5 seconds was 6.3.
g / m ² .

Comparative Example 1 A release paper and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1 except that the stock was adjusted as follows in the production of the base paper for release paper of Example 1. Composition of paper material-Beating degree: 500 ml CSF (softwood kraft pulp) 60 parts-Beating degree: 450 ml CSF (hardwood kraft pulp) 40 parts-30% reinforced rosin sizing agent (trade name: SPE, manufactured by Arakawa Chemical Industries) 0.5 part 0.5% of 30% aluminum sulfate Note that the water absorption of the back surface of the base paper for release paper manufactured by the above method was measured under the condition of a water absorption time of 5 seconds (Cobb method) and was 2
3.2 g / m ² and formation coefficient were 3.8.

Comparative Example 2 A release paper and an adhesive sheet were obtained in the same manner as in Comparative Example 1 except that the stock was adjusted as described below in the production of the base paper for release paper of Comparative Example 1. Composition of paper material-Beating degree: 450 ml CSF (softwood kraft pulp) 60 parts-Beating degree: 350 ml CSF (hardwood kraft pulp) 40 parts-30% reinforced rosin sizing agent (trade name: SPE, manufactured by Arakawa Chemical Industries) 0.5 part 0.5% of 30% aluminum sulfate Note that the water absorption of the back surface of the base paper for release paper manufactured by the above method was measured under the condition of a water absorption time of 5 seconds (Cobb method) and was 2
7.8 g / m ² and formation coefficient were 3.3.

Comparative Example 3 A release paper and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1, except that the stock was prepared as described below in the production of the base paper for release paper of Example 1. Composition of paper material-Beating degree: 520 ml CSF (softwood kraft pulp) 60 parts-Beating degree: 420 ml CSF (hardwood kraft pulp) 40 parts-30% reinforced rosin sizing agent (trade name: SPE, manufactured by Arakawa Chemical Industries) 5 parts-30 % Aluminum sulfate 5 parts The water absorption of the back surface of the base paper for release paper manufactured by the above method was measured under the condition of a water absorption time of 5 seconds (Cobb method).
8 g / m ² and formation coefficient were 3.5.

Comparative Example 4 A release paper and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1 except that the stock was prepared as described below in the production of the base paper for release paper of Example 1. -Degree of beating: 60 parts of 500 ml CSF (softwood kraft pulp)-Degree of beating: 40 parts of 450 ml CSF (hardwood kraft pulp)-30 parts reinforced rosin sizing agent (trade name: SPE, Arakawa Chemical Industries) 2.0 parts-30% sulfuric acid Aluminum 3 parts The water absorption measured on the back surface of the base paper for release paper manufactured by the above method under the condition of water absorption time of 5 seconds (Cobb method) is 4.
1 g / m ² and the formation coefficient were 3.7.

Comparative Example 5 The procedure of Example 5 was repeated except that the styrene-butadiene copolymer latex was changed to oxidized starch (trade name: Ace A, manufactured by Oji Corntarch Co.) in the production of the base paper for release paper of Example 5. Thus, a release paper and a pressure-sensitive adhesive sheet were obtained. In addition,
The water absorption of the back surface of the base paper for release paper manufactured by the above method, measured under the condition of a water absorption time of 5 seconds (Cobb method), is 31.4 g.
/ M ² , and the formation coefficient were 3.2.

[Evaluation of Roughness] Roughness on the surface of the obtained pressure-sensitive adhesive sheet was visually evaluated according to the following criteria. ◎: no unevenness ○: slight unevenness but no problem in practical use △: unevenness ×: many unevenness

[0064]

[Table 1]

[0065]

As is evident from the results in Table 1, when the base paper for release paper of the present invention is used as a release paper for an adhesive sheet using a film as a surface base material, the base paper has a high-grade appearance without any unevenness on the surface. It can provide a pressure-sensitive adhesive sheet, and the water absorption can be measured by using an existing paper machine or other equipment by adding the internal sizing agent to be added to the stock, or by mixing the surface sizing agent into the size press coating solution. Can be easily manufactured by adjusting to a certain range, and is extremely excellent in practicality.

Claims (1)

[Claims] 1. A release paper base paper for an adhesive sheet to which a release agent layer and an adhesive layer are sequentially provided and a film is bonded via the adhesive layer, opposite to a surface of the release paper base paper on which a release agent is applied. Surface has a water absorption of 5 to 20 g / measured (Cobb method) under the condition of a water absorption time of 5 seconds specified in JIS P8140.
m ² , and a formation coefficient F having a relationship of the following expression between the average density D ₁ of the shadow image and the standard deviation D ₂ of the shadow image due to the transmitted light by the total KSK background of the release paper base paper is 3.5 or less. A base paper for release paper, wherein F = (D ₂ / D ₁ ) × 100