JPH0711204A - Self-adhesive tape for decoration - Google Patents

Abstract

PURPOSE:To obtain a self-adhesive sheet for decoration, free from occurrence of adhesive transfer in removal. CONSTITUTION:This self-adhesive tape for decoration is obtained by forming a crosslinkable acrylic self-adhesive layer on one side of a base film. In this self-adhesive tape for decoration, the crosslinkable acrylic self-adhesive is prepared by blending 5 to 9 pts.wt. isocyanate-based crosslinking agent with 100 pts.wt. crosslinkable acrylic polymer (e.g. a copolymer of 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate and acrylic acid).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet for decoration, which does not cause adhesive residue during re-peeling.

[0002]

2. Description of the Related Art Conventionally, there is known a pressure-sensitive adhesive sheet for decoration in which a pressure-sensitive adhesive layer is formed on one surface of an opaque, transparent or translucent, mainly polyvinyl chloride base film containing a pigment. This decorative pressure-sensitive adhesive sheet is to be attached to a material to be decorated by using an adhesive layer, and to exert a decorative effect by the color or pattern of the surface side of the base film, and in recent years, instead of painting. It is used in the field of displays such as labels and stickers, advertisements and billboards (for example, JP-A-63-54483 and JP-A-2-84476).

Acrylic adhesives, vinyl acetate adhesives, rubber adhesives, urethane adhesives, silicone adhesives, etc. are proposed as adhesives used in the adhesive layer of conventional decorative adhesive sheets. However, mainly acrylic adhesives, particularly cross-linked acrylic adhesives have been used.

[0004] For example, Japanese Patent Laid-Open No. 2-84476 discloses a decorative pressure-sensitive adhesive sheet for decoration in which the base film is not turned up by a cutting machine when the base film is cut into a desired shape for use. A pressure-sensitive adhesive sheet is proposed, and as the pressure-sensitive adhesive of the sheet, a crosslinkable acrylic polymer and the crosslinkable acrylic polymer 10
Isocyanate-based crosslinking agent 0.01 to 2 relative to 0 part by weight
A crosslinked acrylic pressure-sensitive adhesive containing 0 parts by weight is used. Then, as the crosslinkable acrylic polymer, unsaturated carboxylic acid ester monomer such as (meth) acrylic acid ester 99.9 to 85 parts by weight and a crosslinkable functional group such as (meth) acrylic acid are used. Copolymers derived from vinyl monomers having from 0.1 to 15 parts by weight are mentioned.

[0005]

However, in the prior art including the above publication, the ratio of the crosslinkable acrylic polymer to the isocyanate crosslinker in the crosslinkable acrylic pressure-sensitive adhesive is, in detail, The cross-linkable acrylic polymer 100 has not been examined and is also used in the examples of the above publications.
Conventionally, a crosslinkable acrylic polymer 10 is used so that 1 part by weight of an isocyanate crosslinking agent is used with respect to parts by weight.
The isocyanate crosslinking agent was used in a ratio of less than 5 parts by weight based on 0 part by weight. Further, the ratio of the isocyanate cross-linking agent has not been studied from the viewpoint of removability of the decorative pressure-sensitive adhesive sheet, such a decorative pressure-sensitive adhesive sheet is a window display or indoor display, or,
In the case of being used for an outdoor signboard that is to be replaced in the short term, removability is required, but there is a problem that adhesive residue is likely to occur during repeeling. This problem was particularly serious when a vinyl chloride plate was used as the adherend.

The present invention has been made in view of the above problems, and an object thereof is to provide a pressure-sensitive adhesive sheet for decoration in which no adhesive residue is generated during re-peeling.

[0007]

The present inventors have found that the above problems can be solved by setting the compounding ratio of the isocyanate crosslinking agent to the crosslinkable acrylic polymer within a certain range. The present invention has been completed. That is,
The decorative pressure-sensitive adhesive sheet of the present invention is a decorative pressure-sensitive adhesive sheet having a cross-linked acrylic pressure-sensitive adhesive layer provided on one surface of a base film, wherein the cross-linkable acrylic pressure-sensitive adhesive is a cross-linkable acrylic polymer, The crosslinkable acrylic polymer 100
It is characterized by containing 5 to 9 parts by weight of an isocyanate-based crosslinking agent with respect to parts by weight.

The crosslinkable acrylic polymer contained in the crosslinkable acrylic pressure-sensitive adhesive used in the present invention is preferably a copolymer of (meth) acrylic acid ester and a vinyl monomer having a crosslinkable functional group. Examples of the (meth) acrylic acid ester include (meth) acrylic acid alkyl ester, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. Group, 2-ethylhexyl group and the like. As the (meth) acrylic acid ester, two or more kinds may be used in combination.

Vinyl monomer having the above-mentioned crosslinkable functional group
Examples thereof include a vinyl monomer having a carboxyl group such as (meth) acrylic acid and itaconic acid, and a vinyl monomer having a hydroxyl group such as a hydroxyalkyl ester of (meth) acrylic acid. Examples of the hydroxyalkyl group of the hydroxyalkyl ester include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, a hydroxypentyl group and a hydroxyhexyl group. Among these vinyl monomers having a crosslinkable functional group, acrylic acid is particularly preferable.

The proportion of the (meth) acrylic acid ester and the vinyl monomer having a crosslinkable functional group in the production of the above copolymer is such that the crosslinkable functional group is added to the (meth) acrylic acid ester 99, 9 to 85 parts by weight. Having vinyl monomer-0.1
15 parts by weight is preferred. When the amount of vinyl monomer having a crosslinkable functional group increases, the pressure-sensitive adhesive becomes hard and the anchoring property to the base film decreases.

Examples of the isocyanate cross-linking agent contained in the cross-linking acrylic pressure-sensitive adhesive used in the present invention include phenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate and 2,6- Aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, triisocyanate, naphthalene 1,5 diisocyanate; pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate,
4,4'-dicyclohexylmethane diisocyanate and the like can be mentioned.

In the crosslinkable acrylic pressure-sensitive adhesive used in the present invention, the proportion of the crosslinkable acrylic polymer and the isocyanate crosslinker is 5 to 9 with respect to 100 parts by weight of the crosslinkable acrylic polymer. Parts by weight. When the proportion of isocyanate cross-linking agent decreases,
Adhesive residue is generated at the time of re-peeling, and when the amount is large, the adhesive force is reduced and the anchoring property to the base film is reduced.

The thickness of the crosslinkable acrylic pressure-sensitive adhesive layer used in the present invention is preferably 20 to 50 μm from the viewpoint of adhesive strength to an adherend and ease of use.

The substrate film used in the present invention is not particularly limited as long as it can be formed into a film, but a synthetic resin film such as polyvinyl chloride, polyurethane, polyolefin or polyethylene terephthalate is preferable. Can be mentioned. Among these, a polyvinyl chloride film is preferable in terms of flexibility, weather resistance and moldability. The polyvinyl chloride film is obtained, for example, by mixing a polyvinyl chloride with a pigment, a dye, a plasticizer, a stabilizer and the like, and casting or calendering. The thickness of this base film is 50 to 200 μm in terms of ease of use.
Is preferred.

As an example of the method for producing the decorative pressure-sensitive adhesive sheet of the present invention, a predetermined composition of a crosslinkable acrylic polymer, an organic solvent and an isocyanate crosslinker is applied on a substrate film and then dried. Thus, the organic solvent is volatilized and the crosslinkable acrylic polymer is reacted with the isocyanate crosslinking agent to provide a crosslinkable acrylic pressure-sensitive adhesive layer on the base film. The solvent is preferably contained in an amount of 50 to 500 parts by weight with respect to 100 parts by weight of the crosslinkable acrylic polymer. The coating machine that can be used for coating the cross-linked acrylic pressure-sensitive adhesive is not particularly limited as long as it can be used for ordinary pressure-sensitive adhesive solution coating, but it is preferable that the thickness can be accurately adjusted. In addition, a knife coater, a comma roll coater, and a roll coater that can be applied with high productivity are included.

As the coating method, as described above, in addition to the method of directly applying the adhesive solution to the base film and drying, the adhesive solution is once applied to the release paper and dried to form the adhesive layer. A transfer method, etc., in which the film is formed and attached to the above-mentioned substrate film, can be appropriately selected.

The decorative pressure-sensitive adhesive sheet thus produced is usually stored as a laminate in which a release sheet is attached to the pressure-sensitive adhesive layer surface, and the release sheet is peeled off from the pressure-sensitive adhesive layer surface before use. As the release sheet,
It has a supporting force and is not particularly limited as long as it has a release layer capable of releasing the cross-linked acrylic pressure-sensitive adhesive layer on the surface, for example, non-woven fabric, synthetic fiber,
Examples include various sheet-shaped bodies such as a net, paper, a plastic film or a laminate of a polyolefin film and paper coated with a material for forming a release layer. More specifically, paper or polyethylene terephthalate film coated with silicone resin can be used.

[0018]

EXAMPLES Examples of the present invention will be described below. Example 1 (1) Production of Crosslinkable Acrylic Polymer 65 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of butyl acrylate, 10 parts by weight of ethyl acrylate and 3 parts by weight of acrylic acid were charged into a separable flask, and ethyl acetate and A polymerization initiator was added. This solution was heated to 60 ° C. under a nitrogen atmosphere while stirring to initiate polymerization. After reacting at a temperature of 60 ° C. for 3 hours, 2-
A mixture of 32.5 parts by weight of ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 5 parts by weight of ethyl acrylate and 0.5 part by weight of acrylic acid was added dropwise over 1 hour. After the dropping, the reaction was further performed for 3 hours and then at the boiling point for another 1 hour. Next, ethyl acetate was added to obtain a crosslinkable acrylic polymer solution having a solid content concentration of 40% by weight and a viscosity of 5500 centipoise.

(2) Production of pressure-sensitive adhesive layer An amount corresponding to 100 parts by weight of the solid content of the crosslinkable acrylic polymer solution obtained in (1) above, and an isocyanate curing agent (2,4-tolylene diisocyanate) , Nippon Polyurethane Co., Ltd., trade name: Coronate L-55) 5 parts by weight were mixed to obtain a cross-linked acrylic pressure-sensitive adhesive. This adhesive is placed on a release paper so that the thickness after drying becomes 30 μm.
After coating with a comma roll coater, it was dried at 100 ° C. for 2 minutes. (3) Production of Adhesive Sheet for Decorative In order to produce a base film, the following vinyl chloride-based organosol composition was prepared with a dissolver stirrer, which was coated with alkyd resin on fine paper to have a thickness of 170 μm.
Release sheet (manufactured by Dai Nippon Printing Co., Ltd., product name: DNTP-N
ML) coated on a process paper with a comma roll coater, pre-dried at 120 ° C. for 1 minute, and then heated at 200 ° C. for 1 minute to be cured to obtain a base film having a thickness of 50 μm. "Organosol composition" Vinyl chloride resin (manufactured by Zeon Corporation, trade name: Zeon 121) 100 parts by weight Barium / zinc stabilizer (manufactured by Katsuta Kako Co., trade name: BZ-100J) 2 parts by weight benzotriazole UV absorption Agent (manufactured by Ciba Geigy, trade name: Tinuvin 326) 0.5 parts by weight Polyester plasticizer (manufactured by ADEKA ARGUS CO., LTD., Product name: ADEKA SAIZER-PN446) 30 parts by weight hydrocarbon solvent (manufactured by Shell Chemical Co., trade name: Solvesso # 150) 60 parts by weight The pressure-sensitive adhesive layer obtained in the above (2) was laminated on this base film to obtain a decorative pressure-sensitive adhesive sheet of the present invention.

Examples 2 and 3 The amount of the isocyanate curing agent in the step (2) of Example 1 was changed from 5 parts by weight to 7 parts by weight (Example 2) and 9 parts by weight (Example 3). A decorative pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except for.

Comparative Examples 1 and 2 5 parts by weight of the isocyanate curing agent in step (2) of Example 1 was added to 2 parts by weight (Comparative Example 1) and 10 parts by weight.
A decorative pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the weight part (Comparative Example 2) was used.

[0022] Evaluation Examples 1 to 3, as a sample a decorative adhesive sheet of Comparative Examples 1 and 2 were evaluated as follows. Adhesive strength SP (stainless steel) plate, zinc iron plate, glass plate, and vinyl chloride plate are prepared as adherends, and a sample of 15 m is attached to each.
After sticking a piece cut into mx 100 mm, pressing it back and forth once with a roller of 2 kg in weight, and 15 minutes and 1 day later, check the load when peeled in the direction of 180 degrees at a speed of 300 mm / min It was Removability The sample adhered to each adherend in the same manner as above was peeled after 2 days in a 180 degree direction at a speed of 2000 mm / min, and the adhesive residue state was examined according to the following evaluation criteria. A: No adhesive residue X: Adhesive residue present The evaluation results are shown in Tables 1 and 2.

[0023]

[Table 1]

[0024]

[Table 2]

The decorative pressure-sensitive adhesive sheet obtained in Comparative Example 2 was
No adhesive residue was generated during re-peeling, but the adhesive strength was extremely low and it was easily peeled off from the adherend, which was not practical.

[0026]

The structure of the decorative pressure-sensitive adhesive sheet of the present invention is as described above, and no adhesive residue is generated during re-peeling. Therefore, it is suitable for a display such as a wind display, an indoor display, or an application requiring removability such as an outdoor signboard to be replaced in a short period of time. In particular, it is suitable when the adherend is a vinyl chloride plate or a glass plate.

Claims (1)

[Claims] 1. A decorative pressure-sensitive adhesive sheet having a cross-linked acrylic pressure-sensitive adhesive layer provided on one surface of a base film, comprising:
The crosslinkable acrylic pressure-sensitive adhesive is characterized by containing a crosslinkable acrylic polymer and 5 to 9 parts by weight of an isocyanate crosslinker per 100 parts by weight of the crosslinkable acrylic polymer. Adhesive sheet for decoration.