JPH11277697A - Release paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a release paper not especially generating a curl when finished into a self-adhesive sheet and excellent in blocking properties and printing aptitude. SOLUTION: A release paper is constituted by applying a treatment soln. based on a pigment and a polyvinylidene chloride latex to the opposite surface provided with a release agent layer of polyethylene film laminated paper wherein a polyethylene film is laminated to the single surface of raw paper. The treatment soln. is prepared by adding 100-500 pts.wt. polyvinylidene chloride latex to 100 pts.wt. pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release paper, and more particularly to a release paper used for an adhesive sheet. More specifically, when finished to an adhesive sheet,
Particularly, the present invention relates to a release paper having no curling and excellent blocking properties and printability.

[0002]

2. Description of the Related Art Adhesive sheets are used as labels, seals, stickers, patches, and the like for a wide range of applications such as commercial use, office use, and home use. This pressure-sensitive adhesive sheet is generally formed by laminating a surface substrate, a pressure-sensitive adhesive layer, and a release paper in this order. Paper, film, metal foil, etc. are used as the surface substrate, and release agents such as silicone compounds and fluorine compounds are applied to release base paper such as high-density paper such as glassine paper, clay coated paper, polyethylene laminated paper, etc. That is used. 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] Such an adhesive sheet is likely to be curled due to release paper. In particular, this is likely to occur in a polyethylene film laminate type in which a polyethylene film is laminated on one side of a base paper and a release agent layer is provided on the polyethylene film side. In other words, release paper in which a polyethylene film is laminated on one side of the base paper, when a change in humidity occurs, the polyethylene film surface hardly absorbs and dehumidifies moisture, hardly absorbs and desorbs moisture due to the change in humidity, and expands and contracts the base paper. Nor. Conversely, the surface opposite to the polyethylene film laminate surface is directly exposed to the outside air, and is susceptible to changes in humidity. In other words, under a high humidity atmosphere, the base paper absorbs moisture, the fibers are stretched, and the curl has a concave surface on which the polyethylene film is laminated. Under a low-humidity atmosphere, the base paper releases moisture, and the fibers shrink, resulting in a curl having a convex surface on which the polyethylene film is laminated.

[0004] Therefore, for the purpose of preventing moisture absorption and desorption due to a change in humidity, a so-called double-sided polyethylene film laminate type in which a polyethylene film is laminated on the side opposite to the side on which the release agent layer is provided has been proposed. However, in recent years, demands for pressure-sensitive adhesive sheets have diversified, and precautions and usage methods for pressure-sensitive adhesive sheets may be printed on a surface of a release paper opposite to a surface on which a release agent layer is provided (hereinafter referred to as a back surface of the release paper). Yes, if a polyethylene film is laminated on the back of the release paper, printability such as ink adhesion becomes insufficient.

In order to impart printability to the backside of the release paper, a method has been proposed in which a resin layer having a small moisture absorption and release is provided on the backside of the release paper to prevent curling. In this method, the effect of suppressing moisture absorption and moisture release to some extent to prevent curl is recognized, but when the surface substrate is a film such as YUPO or PET,
Blocking with the back of the release paper occurs. In addition, a resin having good film-forming properties is used to prevent moisture absorption and release, and printability such as ink adhesion becomes insufficient.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a release paper using a polyethylene film-laminated paper in which a polyethylene film is laminated on one side of a base paper as a release substrate. The present invention relates to a release paper having no blocking property and excellent in blocking property and printability.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above situation, and as a result, have found that, on one side of a base paper, a polyethylene film-laminated paper is provided with a release agent layer of a polyethylene film-laminated paper. It has been found that the object of the present invention can be achieved by applying a treatment liquid containing polyvinylidene chloride latex as a main component, and the present invention has been completed.

[0008] The present invention relates to a release paper in which a polyethylene film laminated paper obtained by laminating a polyethylene film on one side of a base paper is used as a release substrate, and a release agent layer is provided on the surface of the release substrate on which the polyethylene film is laminated. Release paper formed by applying a treatment liquid containing a pigment and polyvinylidene chloride latex as main components to the surface opposite to the agent layer, and more preferably, the treatment liquid is polychlorinated with respect to 100 parts by weight of the solid content of the pigment. A release paper containing 100 to 500 parts by weight of vinylidene latex in solid content.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The release paper of the present invention uses a polyethylene film laminated paper in which a polyethylene film is laminated on one side of a base paper as a release substrate, and a release agent layer is provided on the surface of the release substrate on which the polyethylene film is laminated. A release paper characterized in that a treatment liquid containing a pigment and polyvinylidene chloride latex as main components is applied to a surface of the release paper which is opposite to the release agent layer.

In general, when a polyethylene film laminate type release paper is used, the resin applied to the back surface of the release paper includes styrene resin, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, ethylene- Examples thereof include an acrylic acid copolymer resin, an ethylene-methacrylic acid copolymer resin, a urethane resin, an acrylate copolymer resin, a methacrylate copolymer resin, and a styrene-butadiene copolymer resin.

The resin described above has an effect of suppressing the absorption and release of moisture of the base paper to some extent, but is not sufficient and cannot completely prevent curling. In addition, particularly when a film is used as the surface substrate, blocking occurs between the film surface and the back surface of the release paper (resin), and the film and the resin adhere to each other, especially under high humidity, so that the film cannot be peeled off, resulting in a fatal obstacle. Becomes Also, when printing on the back of the release paper, for example, the ink stays on the surface and the adhesion is insufficient,
Problems such as easy peeling occur.

In the present invention, a treatment liquid containing a pigment and polyvinylidene chloride latex as main components is applied to the back surface of the release paper. However, the present inventors examined various resins and found that polyvinylidene chloride latex was It has been found that the effect of suppressing the absorption and release of moisture of the base paper is the highest. In other words, it has fine voids with a pore size of 0.1 to 1.0 microns,
It has been found that the base paper, which is porous and rich in moisture absorption / desorption, has remarkable film-forming properties and humidity barrier properties for suppressing moisture absorption / desorption.

The polyvinylidene chloride latex used in the present invention is not particularly limited, and may be those generally used for processing packaging materials. Polyvinylidene chloride is widely known as a raw material for wraps used as a packaging material. The basic composition is a copolymer of polyvinylidene chloride and vinyl chloride or acrylic acid ester, and generally contains a small amount of a plasticizer. Many polyvinylidene chloride latexes are 90
Contains polyvinylidene chloride by weight, but polyvinylidene chloride alone is inferior in processability because it is inferior in processability, but is copolymerized with acrylate or vinyl chloride. Therefore, the content is preferably up to about 20 parts by weight.

The lower the glass transition point of the copolymer is, the better the film-forming property is, and the lower the glass transition point of vinyl chloride or acrylic acid ester copolymerized with vinylidene chloride is desirably. The glass transition point of vinyl chloride or acrylic acid ester is preferably from -30 to 30 ° C. If the glass transition point is lower than -30 ° C, the adhesiveness of the resin is increased and the blocking is deteriorated. Further, when the temperature exceeds 30 ° C., the film-forming property is deteriorated, and the curl is adversely affected.

In the present invention, the treatment liquid contains a pigment as a main component, but the vinylidene chloride latex alone has good film-forming properties and humidity barrier properties, and has the effect of preventing curling. Like other resins, the blocking properties and printability become insufficient. As a result of intensive studies, the present inventors have completed the present invention by using polyvinylidene chloride and a pigment as the main components of the coating liquid on the back surface of the release paper. That is, it has been found that by containing the pigment, all of the curl prevention, the blocking property, and the printability are satisfied.
When the pigment is contained, minute irregularities are formed on the surface of the coating layer on the back surface of the release paper, and when the adhesive sheet is used, there is an effect of preventing blocking with a surface substrate (especially a film having high smoothness). In addition, when a pigment is contained, the ink is adsorbed on the pigment when printing on the back surface of the release paper, and the ink adhesion is improved. Of course, there is no problem in filling the voids between the pigments with the polyvinylidene chloride latex for curling prevention.

The pigment used in the present invention is not particularly limited, and inorganic pigments such as kaolin, clay, aluminum hydroxide, heavy calcium carbonate, light calcium carbonate, satin white, titanium dioxide, plastic pigment and the like can be used.
An organic pigment is appropriately selected and used. Of course, two or more pigments can be used in combination.

The weight ratio of the solid content of the pigment and the polyvinylidene chloride latex is not particularly limited.
Preferably, the amount is in the range of 100 to 500 parts by weight of solid content of polyvinylidene chloride latex with respect to 00 parts by weight. If it is less than 100 parts by weight, curling due to a change in humidity occurs, and if it exceeds 500 parts by weight, blocking properties,
It is preferable to avoid this because printability deteriorates. In addition, as long as the object of the present invention is not impaired, various auxiliary agents such as a lubricant, an antifoaming agent, a coloring agent, a flow modifier, a water-proofing agent, an oil-proofing agent, and a curing agent are appropriately blended as needed. It is also possible to use two or more auxiliaries in combination.

The coating amount of the treatment liquid of the present invention is 2.
It is desirable to adjust so as to be in the range of about 0 to 15 g / m ² . If it is less than 2.0 g / m ² , the desired effect cannot be obtained, and if it exceeds 15 g / m ² , the effect is saturated and it is not economically preferable. Further, as a coating apparatus for forming a treatment liquid layer, for example, various general coaters such as a bar coater, a gravure coater, and an air knife coater, or a printing machine are appropriately used. The coating may be performed by two or more coating operations.

The base paper used in the present invention is made of hardwood bleached kraft pulp, softwood bleached kraft pulp, or other chemical or mechanical pulp as a main raw material. Alternatively, it includes high-quality paper, medium-quality paper, matte paper, kraft paper, glassine paper, and the like made by a round-mesh paper machine. The base paper may contain papermaking auxiliary chemicals such as a paper strength agent, a sizing agent, a filler, and a retention aid. Although not particularly limited, a base paper having a rice tsubo of about 50 to 150 g / m ² is employed.

The polyethylene film in the present invention can be, for example, all of a homopolymer of ethylene and a copolymer mainly composed of ethylene. Specifically, the polyethylene film produced by a low-pressure method includes medium-density polyethylene, high-density polyethylene, Ethylene-vinyl acetate copolymer-vinyl copolymer, ethylene- (meth) acrylate copolymer, ethylene-
(Meth) acrylic acid copolymers and their ionomers are listed, and those produced by a high-pressure method include low-density polyethylenes such as ethylene-propylene copolymers and ethylene-1-butene copolymers. . But,
It is not limited to these.

Extrusion lamination, film lamination, and the like are suitable as the lamination method of the ethylene resin. In order to improve the adhesion on the surface to be laminated, application of an adhesive, ozone treatment, corona discharge treatment, and the like are performed. May be applied. Laminate thickness is 10
30 μm is preferred.

In the present invention, a release agent layer is provided on the surface on which the polyethylene film is laminated, and a silicone resin release agent is preferably used as the release agent. As the silicone resin release agent, a solvent type silicone resin or a non-solvent type silicone resin such as an ultraviolet curing type, an electron beam curing type, and a thermosetting type is appropriately selected and used. The amount of the silicone resin applied is desirably adjusted so as to be in the range of about 0.3 to 3.0 g / m ² in terms of dry weight. 0.3 g / m ²
If it is less than 3.0 g, the desired peeling strength cannot be obtained, and if it exceeds 3.0 g / m ² , the effect is saturated and it is not economically preferable.

Further, as a coating apparatus for forming the release agent layer, various coaters for applying a general release agent such as a roll coater, a bar coater, a gravure coater or the like, or a printing machine are appropriately used.

The method of forming the pressure-sensitive adhesive sheet using the release paper of the present invention is carried out according to a conventional method, for example, natural rubber, styrene-butadiene copolymer, styrene-isoprene block copolymer, recycled rubber, natural rubber, A rubber-based adhesive such as a synthetic rubber, an acrylic-based, or a silicone-based adhesive is appropriately used. These adhesives are solvent-based, aqueous emulsion-based,
It is applied in the form of a hot melt system or a liquid curing type by, for example, a knife coater, a roll coater, a die coater, a gravure coater, screen printing, or the like. The coating amount in this case, on a dry weight 10 to 40 g / m ^2, and more preferably is adjusted in the range of about 15-25 g / m ^2. If the amount is less than 10 g / m ² , the effect as a pressure-sensitive adhesive layer is poor, and if it exceeds 40 g / m ² , the effect is saturated, which is not economically preferable.

Examples of the surface substrate include cast coated paper, art paper, coated paper, woodfree paper, thermal paper,
There are synthetic paper, vapor-deposited paper, cloth, nonwoven fabric, metal foil, various polymer films, and the like, which can be used as appropriate according to the use and purpose.

[0026]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but of course, the present invention is not limited to these examples. In the examples, parts and% indicate parts by weight and% by weight of the active ingredient or solid content, respectively, unless otherwise specified.

Example 1 "Manufacture of release paper" A film thickness of 25 μm by a melt extrusion coating method on a felt surface of a high quality paper of 80 g / m ^{2 in} rice tsubo.
Use low-density polyethylene to obtain a resin temperature of 33.
Laminated at 0 ° C.

Next, 4.5 parts of an addition reaction type silicone (trade name: SD7220, manufactured by Toray Dow), 0.5 parts of a platinum catalyst (trade name: SRX212, manufactured by Toray Dow), and 0.5 parts of toluene on the surface of the polyethylene film. 95 parts were prepared, and a coated paper and a release paper were obtained from the obtained silicone solution using a Meyer bar so that the weight after drying was 2.0 g / m ² .

"Preparation and application of backside treatment solution" A treatment solution having the following composition was prepared, and the weight after drying was 7 g / m2 on the surface of the release paper opposite to the surface on which the polyethylene film was laminated, using an air knife coater. ^It was applied so as to obtain a release paper. Kaolin (trade name: HT clay, manufactured by Engelhard)
100 parts Polyvinylidene chloride latex (trade name: L100, manufactured by Asahi Kasei Corporation) 200 parts Water 450 parts

[Production of Adhesive Paper] An acrylic emulsion-type adhesive (trade name: Nicazole L144, manufactured by Nippon Carbide Co., Ltd.) was applied to the above release paper by a reverse roll coater so that the dry weight was 25 g / m ^2. After drying,
A 50 μ transparent PET film was bonded to obtain an adhesive sheet.

Example 2 A release paper was prepared in the same manner as in Example 1 except that the back surface treatment solution was changed to the following composition in the preparation of the back surface treatment solution of Example 1.
An adhesive paper was obtained. 100 parts of calcium carbonate (trade name: Softon 2200, manufactured by Shiraishi calcium) 200 parts of polyvinylidene chloride latex (trade name: L100, manufactured by Asahi Kasei Corporation) 450 parts of water

Example 3 A release paper and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1 except that the composition of the back surface treatment liquid in Example 1 was changed to the following composition. Aluminum hydroxide (trade name: H-42, manufactured by Showa Light Metal Co., Ltd.) 100 parts Polyvinylidene chloride latex (trade name: L100, manufactured by Asahi Kasei Corporation) 300 parts Water 400 parts

Example 4 A release paper was prepared in the same manner as in Example 1 except that the back surface treatment solution was changed to the following composition in the preparation of the back surface treatment solution of Example 1.
An adhesive paper was obtained. Kaolin (product side: HT clay, manufactured by Engelhard)
100 parts polyvinylidene chloride latex (trade name: SF201)
1. Toyo Morton) 70 parts Water 200 parts

Example 5 A release paper was prepared in the same manner as in Example 1 except that the back surface treatment solution was changed to the following composition in the preparation of the back surface treatment solution of Example 1.
An adhesive paper was obtained. Kaolin (product side: HT clay, manufactured by Engelhard)
100 parts polyvinylidene chloride latex (trade name: SF201)
1, Toyo Morton) 600 parts 700 parts water

Comparative Example 1 A release paper was prepared in the same manner as in Example 1 except that the back surface treatment solution was changed to the following composition in the preparation of the back surface treatment solution of Example 1.
An adhesive paper was obtained. 100 parts of polyvinylidene chloride latex (trade name: L100, manufactured by Asahi Kasei Corporation) 100 parts of water

Comparative Example 2 A release paper was prepared in the same manner as in Example 1 except that the back surface treatment solution was changed to the following composition in the preparation of the back surface treatment solution of Example 1.
An adhesive paper was obtained. Kaolin (trade name: HT clay, manufactured by Engelhard)
100 parts Oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch) 50 parts 200 parts water

COMPARATIVE EXAMPLE 3 A release paper was prepared in the same manner as in Example 1 except that the back surface treatment solution was changed to the following composition in the preparation of the back surface treatment solution of Example 1.
An adhesive paper was obtained. Kaolin (trade name: HT clay, manufactured by Engelhard)
100 parts Styrene-butadiene copolymer latex (trade name: Polylac 518, manufactured by Mitsui Chemicals, Inc.) 200 parts Water 300 parts

Comparative Example 4 A release paper was prepared in the same manner as in Example 1 except that the back surface treatment liquid was changed to the following composition in the preparation of the back surface treatment liquid of Example 1.
An adhesive paper was obtained. Kaolin (trade name: HT clay, manufactured by Engelhard)
100 parts Acrylic ester copolymer latex (trade name: Ricabond ET84, manufactured by Chuo Rika Co., Ltd.) 200 parts Water 300 parts

Comparative Example 5 A release paper was prepared in the same manner as in Example 1 except that the back surface treatment liquid was changed to the following composition in the preparation of the back surface treatment liquid of Example 1.
An adhesive paper was obtained. Styrene-butadiene copolymer latex (trade name: L
1571, manufactured by Asahi Kasei Corporation) 100 parts Water 100 parts

The release papers and pressure-sensitive adhesive sheets obtained in the examples and comparative examples were subjected to the following evaluation tests. (1) Curling of the pressure-sensitive adhesive sheet The obtained pressure-sensitive adhesive sheet was cut into a piece of 210 mm x 297 mm under a high humidity atmosphere of 30 ° C and 80% RH and at a temperature of 10 ° C and 15%.
The sample was left in a low humidity atmosphere of 2% RH for 2 hours, and the average of the heights of the four corners was measured. The measured values were evaluated according to the following evaluation criteria to evaluate curl. ：: 0 to 5 mm, practically no problem at all. Δ: 5 to 10 mm, slightly curled, but at a level that does not pose a problem in practical use ×: 10 mm to, curl is large and poses a practical problem.

(2) Blocking property The obtained pressure-sensitive adhesive sheet was taken up at room temperature for one week,
The blocking property between the surface substrate and the backside of the release paper was evaluated. ：: No blocking at all Δ: Slight blocking but no practical problem. X: Blocking is remarkable and poses a practical problem.

(3) Printing Suitability A UV curing type ink was printed on the back surface of the obtained release paper by a printing machine and dried by UV. A cellophane tape was stuck on the printed surface on the back side of the release paper, and then the adhesion of the peeled ink was evaluated. ：: The ink does not fall off the back surface of the release paper at all. Δ: The ink is slightly dropped from the back surface of the release paper. X: The ink drops off considerably from the back surface of the release paper.

[0043]

[Table 1]

[0044]

As is clear from Table 1, when the release paper of the present invention is finished into an adhesive sheet, the release paper has good curl against a change in humidity, does not block the surface substrate, and has excellent printability. It is.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09J 7/02 C09J 7/02 Z D21H 19/44 D21H 27/00 27/00 1/28 Z 5/00 B

Claims (2)

[Claims] 1. A release paper comprising a single-sided polyethylene film-laminated paper as a release substrate and a release agent layer provided on the polyethylene film surface of the release substrate, wherein a pigment and polyvinylidene chloride latex are coated on the paper surface opposite to the release agent layer. Release paper characterized by being coated with a treatment liquid contained as a main component. 2. The release paper according to claim 1, wherein the treatment liquid contains 100 to 500 parts by weight of polyvinylidene chloride latex per 100 parts by weight of the pigment.