JP2712127B2 - Production method of adhesive sheet - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a pressure-sensitive adhesive sheet, and more particularly to a method for producing a pressure-sensitive adhesive sheet which is free from curling and excellent in sheet-passing suitability and copying machine suitability. is there.

[Background Art] Adhesive sheets are used as labels, seals, stickers, patches, and the like in a very wide range of applications such as commercial, office, and home use. The general configuration of this pressure-sensitive adhesive sheet is a state in which a pressure-sensitive adhesive is sandwiched between a surface substrate and a release sheet, and a paper, film, metal foil, or the like is used for the surface substrate, and the release sheet is used as a release sheet. For example, a material obtained by applying a release agent such as a silicone compound or a fluorine compound to a release substrate such as a high-density base paper such as glassine paper, clay-coated paper, or polylaminate base paper 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.

"Problem to be Solved by the Invention" Such a pressure-sensitive adhesive sheet is likely to be curled due to a release sheet. That is, in a general manufacturing process of a pressure-sensitive adhesive sheet, a release agent is usually applied to a release substrate and dried, and then the pressure-sensitive adhesive is applied and dried on the release agent layer and then bonded to a surface substrate. It shrinks in the drying step, and the reactivity to moisture is extremely high. For this reason, if uneven moisture absorption or water absorption occurs due to a change in the external environment or the like, curling occurs immediately. In particular, when using a high-beaten, high-density paper such as glassine paper as the release substrate, it shrinks more than ordinary paper during drying, so it should absorb the swelling of fibers caused by moisture absorption and water absorption. There are very few voids and consequently curling is particularly pronounced.

The curl of the pressure-sensitive adhesive sheet caused by the release sheet as described above can be caused, for example, by a process such as printing, die cutting, and sheet cutting on the pressure-sensitive adhesive sheet to be processed into a label or a seal. And the like, and when copying with a copying machine, a paper passing failure or a transfer failure occurs, which is a very serious obstacle in workability and quality.

In order to correct the curl of the adhesive sheet, use of a curl breaker that sharply bends the adhesive sheet in the direction opposite to the curl direction, a method of attaching an air conditioner and performing steam damping, etc. have been proposed. In addition to the complexity, the effect is insufficient, and satisfactory results have not always been obtained.

In view of this situation, the present inventors have conducted intensive studies on a method of preventing the pressure-sensitive adhesive sheet from curling due to the release sheet. As a result, after forming the release agent layer, a high glass having a specific glass transition temperature on the back surface of the release substrate has been obtained. It has been found that the above-mentioned difficulties can be solved very efficiently by applying or impregnating a treatment liquid containing molecules as a main component, and the present invention has been completed.

"Means for Solving the Problems" The present invention provides an undercoat layer on a release substrate, applies a release agent on the undercoat layer and drys it to form a release agent layer, and applies and dries an adhesive on the release agent layer. Forming a pressure-sensitive adhesive layer, then, in a method for producing a pressure-sensitive adhesive sheet by laminating a surface substrate, after applying and drying a release agent, on the surface of the release substrate on which the release agent layer is not provided, a glass transition temperature of -10 to A method for producing a pressure-sensitive adhesive sheet, comprising applying or impregnating a curl prevention treatment solution containing a polymer at 70 ° C. as a main component.

In the present invention, as the polymer having a glass transition temperature of −10 to 70 ° C. used as a main component of the curl prevention treatment solution,
Ethylene resin, propylene resin, styrene resin, vinyl chloride resin, ethylene-vinyl acetate copolymer resin, ethylene-vinyl chloride copolymer resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-acrylate copolymer resin ,
Ethylene-methacrylate copolymer resin, amide resin,
Water-dispersible or water-soluble polymers such as nitrile resin, urethane resin, acrylate polymer resin or copolymer resin, methacrylate polymer resin or copolymer resin are exemplified.

Among them, ethylene-vinyl acetate copolymer resin, ethylene-vinyl chloride copolymer resin, vinyl chloride-vinyl acetate copolymer resin, acrylate polymer resin or copolymer resin, methacrylate polymer resin or Copolymer resins are preferably used because they have excellent effects of the present invention.

Incidentally, the method for producing the polymer used in the present invention is not particularly limited, for example, in water or a solvent, a chain transfer agent, a method of solution polymerization in the presence of a polymerization initiator and the like, It is produced by a method of emulsion polymerization in an aqueous system in the presence of a chain transfer agent, a polymerization initiator, an emulsifier (dispersant) and the like.

In the present invention, the glass transition temperature of the polymer thus obtained is important, and a polymer having a glass transition temperature of −10 to 70 ° C. is selectively used. By the way, when the glass transition temperature is lower than -10 ° C, there is a problem that the film becomes too sticky and causes blocking.On the contrary, when the glass transition temperature is higher than 70 ° C, the obtained film becomes too hard and curls on the surface coated with the processing liquid. There is a problem that causes.

The treatment liquid containing the specific polymer of the present invention is desirably prepared as an aqueous treatment liquid from the viewpoint of curl correction effect, coating safety, and the like.

In the polymer as described above, as long as the desired effect of the present invention is not impaired, for example, cellulose derivatives such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, dextrin, acid-treated starch, oxidized starch, cross-linked starch, starch ester And various water-soluble natural polymers such as starch derivatives such as graft copolymerized starch; polyhydric alcohols such as ethylene glycol, glycerin, trimethylolpropane, and diethylene glycol; and polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Water-soluble plasticizer;
An antifoaming agent; a penetrating agent; a wetting agent; a lubricant; a leveling agent; a hardening agent; a thickening agent;

The treatment liquid of the present invention contains the specific polymer as a main component,
It is prepared by adding various additives as necessary, but it is desirable that the concentration of the treatment liquid is adjusted to be in the range of 1 to 50% by weight, preferably 2 to 20% by weight.

The step of applying or impregnating the treatment liquid thus prepared on the back surface of the release substrate may be performed after a release agent is applied to the release substrate and dried to form a release agent layer. The treatment may be carried out before or after processing, and furthermore, the treatment may be carried out in any steps such as an adhesive application step and a bonding step. There is no particular limitation on the method of applying or impregnating the treatment liquid to the release substrate,
For example, various devices such as an air knife coater, a roll coater, a gravure coater, a bar coater, a blade coater, and a size press coater are appropriately used.

The amount of coating or impregnation is preferably adjusted in the range of about 0.05 to 20 g / m ² by dry weight, in particular about 0.1 to 8 g / m ² is desirable.

Various fiber sheets such as high quality paper having a basis weight of about 30 to 300 g / m ² are used as the release substrate. An undercoat layer is formed on the release substrate for the purpose of preventing penetration of the release agent. As a main component of the undercoat layer, for example, a polymer such as a water-soluble acrylate copolymer having a glass transition temperature of −60 to 20 ° C. containing an emulsifier of 2 to 10% by weight is used. The undercoat layer may further contain an antiblocking agent and the like, if necessary.

A release agent is applied and dried on the undercoat layer to obtain a release sheet. The release agent is not particularly limited, and various silicone compounds, fluorine compounds and the like are applied according to a conventional method.

The release sheet thus obtained has an undercoat layer formed on a release substrate, and further has a back surface of the release sheet coated or impregnated with a treatment liquid containing a polymer having a specific glass transition temperature as a main component. In the case of finishing, the occurrence of the curl is effectively prevented, and a pressure-sensitive adhesive sheet excellent in sheet-passing suitability, copying machine suitability, and the like can be formed.

Solvent type adhesive on the release sheet thus obtained,
An emulsion-type adhesive, a hot-melt-type adhesive or the like is applied and dried, and a surface base material is bonded to perform humidity control or the like, thereby completing an adhesive sheet.

The surface substrate is not particularly limited, and paper, a film, a metal foil, or the like is used.

"Examples" Hereinafter, the present invention will be described more specifically with reference to Examples, but of course, the present invention is not limited thereto. In addition, the coating amount, the number of copies, the mixing ratio, and the like in the examples are all represented by solid contents.

Example 1 270 g of butyl acrylate, 15 g of acrylic acid, 113 g of acrylonitrile, 2 g of N-methylolacrylamide, 5 g of a polyoxyethylene nonylphenol ether emulsifier,
An emulsified monomer mixture (I) comprising 5 g of an oxyethylene / oxypropylene block polymer emulsifier and 170 g of ion-exchanged water was prepared.

Next, a stirrer, cooler, dropping funnel, nitrogen suction pipe,
A 2-liter four-necked flask equipped with a thermometer was charged with 240 g of ion-exchanged water, 2 g of a 1: 1 mixture of a polyoxyethylene nonylphenol ether emulsifier and an oxyethylene / oxypropylene block polymer emulsifier, and 0.8 g of potassium persulfate. After the temperature was raised to 70 ° C. while purging with nitrogen, 1/6 of the emulsified monomer mixture (I) was added dropwise. When the reaction rate reached 90%, the remaining emulsified monomer mixture (I) was added dropwise over 2 hours to polymerize. After completion of the dropwise addition, the mixture was aged at 70 ° C. for 2 hours to complete the reaction. After completion of the aging, the contents of the flask were cooled to 60 ° C., and a neutralization reaction was performed by adding an aqueous sodium hydroxide solution. After the completion of the reaction, the mixture was vigorously stirred to obtain a water-dispersible copolymer used in the present invention.

The glass transition temperature of the obtained water-dispersible copolymer is -29 ° C.
And the average particle size was 0.3 μm.

75 parts by weight of the water-dispersible copolymer is added to oxidized starch (trade name:
Ace C, manufactured by Oji Corn Starch Co., Ltd.), 24 parts by weight of an aqueous solution, and 1 part by weight of colloidal silica (trade name: Snowtex 30, Nissan Chemical Industries, Ltd.) were added to a concentration of 30 parts.
By weight, an aqueous coating liquid (II) for an undercoat layer was prepared.

The aqueous coating solution (II) for the undercoat layer is coated on a high-quality paper (peeling substrate) having a basis weight of 50 g / m ² and a thickness of 65 μm with a bar coater so that the dry coating amount is 4 g / m ^2, and the coating is performed at 120 ° C. Dry for 1 minute.

On this undercoat layer, a silicone release agent (trade name: SRX-21)
A 1% toluene solution of Toray Silicone Co., Ltd.) was applied using a bar coater so that the dry coating amount was 1 g / m ^2.
After drying in an oven at 30 ° C. for 1 minute, a release sheet was obtained.

An acrylic emulsion pressure-sensitive adhesive (trade name: Nicazole TS-662, manufactured by Nippon Carbide Co., Ltd.) was applied to the release agent-coated surface of the release sheet with a reverse roll coater at a dry coating amount of 25 g /
m ² and dried in an oven at 120 ° C. for 1 minute. Next, on this adhesive layer, a basis weight of 40
g / m ² , 50μm thick high quality paper is laminated and pressed with a press roll, and then a treatment liquid of the following composition is applied to the back of the release sheet with a bar coater so that the dry coating amount is 0.5 g / m ^2. 70
It dried at 30 degreeC for 30 second, and produced the adhesive sheet.

Treatment liquid composition Ethylene / vinyl chloride copolymer resin (glass transition temperature 30
Aqueous solution containing 10 parts by weight, 1 part by weight of glycerin, 0.1 part by weight of polyoxyethylene monooleate and 0.1 part by weight of colloidal silica (concentration: 10% by weight).

The obtained pressure-sensitive adhesive sheet had no curl, and had extremely good paper-passing suitability and copy suitability with a copying machine (trade name: SF-8100, manufactured by Sharp Corporation).

Example 2 A release sheet was obtained in the same manner as in Example 1 except that high-quality paper having a basis weight of 60 g / m ² and a thickness of 82 μm was used as a release substrate.

Instead of the treatment liquid used in Example 1, a treatment liquid having the following composition was applied to the back surface of the release sheet using an air knife coater so that the dry coating amount was 2 g / m ^2. An adhesive (trade name: Oribain BPS-2411, manufactured by Toyo Ink Mfg. Co., Ltd.) was applied using a reverse roll coater so that the dry coating amount was 20 g / m ^2, and dried at 110 ° C. for 1 minute. On this pressure-sensitive adhesive layer, as a surface base material, basis weight 54 g / m ² , thickness
A high-quality paper of 73 μm was stacked and bonded with a press roll to produce an adhesive sheet.

Treatment liquid composition Acrylic ester copolymer resin (glass transition temperature 70
° C) (Product name: Licabond SA-Z713, manufactured by Chuo Rika Kogyo)
An aqueous coating solution (concentration: 15% by weight) containing 5 parts by weight, 1 part by weight of polyethylene glycol, 0.1 part by weight of dioctyl sodium sulfosuccinate, and 0.1 part by weight of a wax emulsion.

The obtained pressure-sensitive adhesive sheet was free from curling, and had extremely good paper-passing and copying suitability in a copying machine.

Example 3 The same undercoat layer aqueous coating liquid (II) as in Example 1 was applied to a high-quality paper having a basis weight of 40 g / m ² and a thickness of 50 μm using a bar coater so that the dry coating amount was 5 g / m ^2. And dried at 120 ° C. for 1 minute.

On this undercoat layer, a silicone release agent (trade name: SD-722)
(Toray Silicone Co., Ltd.) in a 6% toluene solution was applied by a bar coater so that the dry coating amount was 0.8 g / m ^2, and dried in an oven at 130 ° C. for 1 minute to obtain a release sheet.

An acrylic emulsion adhesive (trade name: Oribain BPW-311) is applied to the release agent application surface (that is, the surface) of the release sheet.
0, manufactured by Toyo Ink Mfg. Co., Ltd.) was applied by a slot die coater so that the dry coating amount was 20 g / m ² , and dried in a 110 ° C. oven for 1 minute. Next, a high-quality paper having a basis weight of 35 g / m ² and a thickness of 47 μm as a surface substrate is laminated on the pressure-sensitive adhesive layer and bonded with a press roll, and then the back surface of the release sheet (that is, the back surface of the release substrate) is treated with the following composition. liquid dry coating amount of 1 g / m ²
Was applied with a roll coater and dried to produce an adhesive sheet.

Treatment liquid composition Ethylene-vinyl acetate copolymer resin (glass transition temperature: 0 ° C) (trade name: Licabond BE-800, manufactured by Chuo Rika Kogyo Co., Ltd.) 10 parts by weight, colloidal silica 0.5 part by weight, wax emulsion 0.5 part by weight Aqueous coating liquid (concentration 10% by weight).

The obtained pressure-sensitive adhesive sheet was free from curling, and had extremely good paper-passing and copying suitability in a copying machine.

Comparative Example 1 An adhesive sheet was produced in the same manner as in Example 1, except that the treatment liquid applied to the back surface of the release sheet was a treatment liquid having the following composition.

Treatment liquid composition An aqueous coating liquid (concentration: 15% by weight) containing 10 parts by weight of triethylene glycol and 1 part by weight of sodium dioctylsulfosuccinate.

This pressure-sensitive adhesive sheet was curled (curled on the surface substrate side) under high humidity conditions (25 ° C., 90%), and the suitability for paper passing in a copying machine was extremely poor.

Comparative Example 2 A silicone release agent (trade name: SRX-211, manufactured by Toray Silicone Co., Ltd.) was applied to glassine paper having a basis weight of 70 g / m ² and a thickness of 65 μm.
% Toluene solution was applied with a bar coater so that the dry coating amount was 1 g / m ^2, and dried in an oven at 130 ° C. for 1 minute to obtain a release sheet. The same pressure-sensitive adhesive as in Example 1 was applied to the release-coated surface of this release sheet using a reverse roll coater so that the dry coating amount was 25 g / m ^2, and dried in an oven at 120 ° C. for 1 minute. Next, a high-quality paper having a basis weight of 64 g / m ² and a thickness of 76 μm as a surface base material is stacked on the adhesive layer and bonded with a press roll. The composition was applied with a bar coater so as to be 0.8 g / m ² and dried at 70 ° C. for 30 seconds to produce a pressure-sensitive adhesive sheet.

Treatment liquid composition An aqueous coating liquid containing 10 parts by weight of glycerin and 1 part by weight of polyoxyethylene octyl phenyl ether (concentration: 10% by weight).

This pressure-sensitive adhesive sheet was curled (curled on the surface substrate side) under high humidity conditions (25 ° C., 90%), and the suitability for paper passing in a copying machine was extremely poor.

Comparative Example 3 An adhesive sheet was produced in the same manner as in Example 1 except that the treatment liquid applied to the back surface of the release sheet was changed to a treatment liquid having the following composition.

Treatment liquid composition Acrylic ester copolymer resin (glass transition temperature-
Aqueous coating solution (concentration: 10% by weight) containing 10 parts by weight, 1 part by weight of glycerin, and 0.5 part by weight of colloidal silica (48 ° C., trade name: AE-516, manufactured by Japan Synthetic Rubber)

This pressure-sensitive adhesive sheet, when the product is rewound, causes significant blocking on the surface of the front substrate and the back of the release substrate,
The surface of the surface substrate was completely destroyed.

Comparative Example 4 An adhesive sheet was produced in the same manner as in Example 3, except that the treatment liquid applied to the back surface of the release sheet was a treatment liquid having the following composition.

Treatment liquid composition Styrene / maleic anhydride copolymer resin (glass transition temperature 130 ° C, trade name: Script Set 520, manufactured by Monsanto Co.) 15 parts by weight, polypropylene glycol 1 part by weight,
An aqueous coating liquid (concentration: 15% by weight) containing 0.1 part by weight of sodium dioctyl sulfosuccinate and 0.1 part by weight of a wax emulsion.

This pressure-sensitive adhesive sheet was curled under normal humidity (curl on the release substrate side), and was extremely poor in suitability for paper passing in a copying machine.

Curl evaluation J. TAPPI paper pulp test method No. 16-77 was evaluated.

Curl degree = 100 / curl radius (cm) TS indicates forward curl, WS indicates reverse curl.

Suitability for copying machine ：: Jamming is not recognized at all.

X: Jamming occurs remarkably, and there is a practical problem.

"Normal humidity" was measured for 7 hours in an environment of 28 ° C and 60% RH, and "High humidity" was measured for 7 hours in an environment of 25 ° C and 90% RH. Is shown.

 Table 1 shows the above results.

"Effect" The obtained pressure-sensitive adhesive sheet had no curl and was excellent in device suitability.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-75199 (JP, A) JP-A-59-149944 (JP, U)

Claims (1)

(57) [Claims] An undercoat layer is provided on a release substrate, a release agent is applied on the undercoat layer and dried to form a release agent layer, and an adhesive is applied and dried on the release agent layer to form an adhesive layer. Then, in a method for producing a pressure-sensitive adhesive sheet in which a surface substrate is laminated, after applying and drying a release agent, a polymer having a glass transition temperature of −10 to 70 ° C. as a main component is provided on the surface of the release substrate on which the release agent layer is not provided. A method for producing a pressure-sensitive adhesive sheet, characterized by applying or impregnating a curl prevention treatment liquid contained as a component.