JPH10287850A - Repeelable pressure-sensitive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a repeelable pressure-sensitive sheet that pertains to a pressure-sensitive sheet of small adhesion, particularly to a pressure-sensitive sheet that is repeelable and reapplicable with extremely reduced staining of the substrate. SOLUTION: In a repeelable pressure-sensitive sheet, having a repeelable adhesive layer on the surface base material, the adhesive constructing the repeelable adhesive layer mainly contains (meth)acrylic ester copolymer and, in addition, contains 0.5-10 pts.wt. of a crosslinking agent and 0.5-20 pts.wt. of a surface active agent based on the 100 pts.wt. of the (meth)acrylate copolymer.

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 having extremely low adhesive strength, and more particularly to a pressure-sensitive adhesive sheet which can be re-peeled and re-attached with very little adherence.

[0002]

2. Description of the Related Art A pressure-sensitive adhesive sheet generally has a structure in which a pressure-sensitive adhesive layer is formed on a surface substrate and a release sheet is laminated to protect the pressure-sensitive adhesive layer. Widely used such as metal or plastic surface protection films. Recently,
In the field of these pressure-sensitive adhesive sheets and tapes, it is possible to repeatedly adhere and peel to an adherend, and damage the adherend,
The need for a non-contaminating removable type is increasing.

[0003] Such a removable adhesive sheet and tape (hereinafter referred to as a removable adhesive sheet) include:
Very low adhesive strength, so-called weak adhesive acrylic adhesive, weak adhesive rubber adhesive applied to the base material,
There is a product in which a fine spherical pressure-sensitive adhesive is coated on a base material via a binder layer, but after application to an adherend, the adhesive force increases with time, making the peeling operation difficult. Instead, it may rise when attached to a curved surface (so-called edge lift), damage the removable adhesive sheet itself and the adherend, and leave the adhesive on the adherend. There was also a problem in point.

[0004] In addition to the type using an adhesive, an adhesive sheet in which a soft polyvinyl chloride containing a large amount of a plasticizer is disposed on a substrate is also known. Due to the influence, when the sheet is peeled off, the adherend has a disadvantage that the adherend is significantly contaminated. In order to improve the stainability, for example, vinyl chloride is graft-polymerized to polyvinyl ether or acrylate instead of soft polyvinyl chloride described in JP-A-49-97840 and JP-A-49-97841. There has been proposed an adhesive sheet in which a mixture of a plasticizer and a tackifier is disposed on a substrate. However, compositions composed of these soft polyvinyl chlorides and vinyl chloride graft polymers generate chlorine gas when discarded or incinerated, and are liable to generate dioxins and the like. Was.

[0005]

The present invention relates to a pressure-sensitive adhesive sheet, and more particularly, to a pressure-sensitive adhesive sheet having good adhesion and removability to a smooth adherend such as glass, plastic plate, and painted steel plate. The purpose is to provide.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, they have found that the problem can be solved by blending a crosslinking agent and a surfactant with a specific resin component. is there. That is, the present invention relates to a removable pressure-sensitive adhesive sheet having a releasable pressure-sensitive adhesive layer provided on a surface substrate, wherein the pressure-sensitive adhesive constituting the removable pressure-sensitive adhesive layer is (meth)
It contains an acrylate copolymer as a main component, and further contains 0.5 to 10 parts by weight of a crosslinking agent and 0.5 part by weight of a surfactant based on 100 parts by weight of a (meth) acrylate copolymer. It is a removable adhesive sheet characterized by containing 20 parts by weight.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pressure-sensitive adhesive constituting the peelable pressure-sensitive adhesive layer contains a (meth) acrylate copolymer as a main component. For example, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and the like as main monomers, vinyl acetate, methyl methacrylate, methyl acrylate and the like as comonomers, and methacrylic acid, acrylic acid, itaconic acid as functional group-containing monomers,
(Meth) acrylic acid ester copolymers obtained by copolymerizing hydroxyethyl methacrylate and the like can be given. Above all, those containing 2-ethylhexyl acrylate as a main component are preferable because they have a low glass transition temperature and a softening temperature, so that they can be peeled off smoothly and have excellent edge lift suitability.

[0008] Crosslinking agents that can be blended with the copolymer include:
Examples of the crosslinking agent include an isocyanate crosslinking agent, an amine crosslinking agent, a polyol crosslinking agent, an epoxy crosslinking agent, and a metal chelate crosslinking agent. Above all, isocyanate-based cross-linking agents such as toluylene diisocyanate, naphthylene-1,5-diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate are preferably used because they enhance the cohesive strength of the pressure-sensitive adhesive and have good depiction with the substrate. Such a crosslinking agent is used in an amount of 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the (meth) acrylate copolymer. By the way, when the amount is less than 0.5 parts by weight, glue remains on the adherend, and when the amount exceeds 10 parts by weight, label floating occurs.

The present invention is characterized in that a surfactant is further added to the copolymer. Examples of the surfactant include anionic surfactants such as sulfates, sulfonates, fatty acids, and phosphates, aliphatic amine salts, and quaternary surfactants.
Cationic surfactants such as quaternary ammonium salts and polyoxyethylene alkylamines; nonionic surfactants such as fatty acid esters of polyhydric alcohols, polyoxyalkylene condensates and fatty acid alkanolamides; and amphoteric surfactants. Can be Above all, nonionic surfactants are more preferable because they cause less peeling. For example, preferable materials include a glycerin derivative, a sorbitan derivative, an ethylene glycol derivative, a propylene glycol derivative, a pentaerythritol derivative, and a polyglycerin derivative.

As for the mixing ratio of the surfactant to be mixed with the copolymer, it is necessary to mix 0.5 to 20 parts by weight of the surfactant with respect to 100 parts by weight of the copolymer. It is 5 to 10 parts by weight. If the amount is less than 0.5 parts by weight, the adhesive will remain when the adhesive sheet is removed again, and if it exceeds 20 parts by weight, floating from the adherend and clouding of the adherend will occur.

As a method for processing the pressure-sensitive adhesive of the present invention into the following substrate, each component is mixed and dissolved in a solvent such as ethyl acetate, toluene, n-hexane or the like, and the solid content is 10 to 80. It is adjusted as a weight% adhesive coating liquid. The pressure-sensitive adhesive coating liquid thus adjusted is applied on a release sheet in an amount of 0.01 to
It is manufactured by applying to a thickness of 0.3 mm, drying and laminating and winding it on a surface substrate.

As a coating device for the pressure-sensitive adhesive layer, a usual coating machine, for example, a knife coater, a roll coater, a comma coater, a bar coater, a gravure coater, a lip coater, a die coater, a screen coater, etc. Can be. Examples of the surface substrate include sheets or tapes such as plastic films, papers, nonwoven fabrics, and plastic or rubber foams.

As the release sheet, a base material using polyethylene terephthalate, polypropylene, or the like as a plastic film;
One using glassine paper or the like may be used. The release agent is not particularly limited, but it is preferable to use an appropriate release agent such as a silicone-based or non-silicone-based one depending on the application.

[0014]

EXAMPLES The removable pressure-sensitive adhesive sheet of the present invention will be described based on examples, but the present invention is not limited to these examples.

Example 1 "Preparation of pressure-sensitive adhesive" A crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L) was added to 100 parts by weight of a solvent-based pressure-sensitive adhesive copolymerized with 2-ethylhexyl acrylate as a main component. 1 part by weight, nonionic propylene glycol derivative as surfactant (manufactured by Kao Corporation, trade name:
(Homotex PS-90) 0.5 part by weight was mixed and sufficiently stirred to obtain an adhesive. "Production of pressure-sensitive adhesive sheet" A release sheet (manufactured by Oji Paper Co., Ltd., trade name: 84GPS) in which a silicone-based release agent layer was provided on one-sided polylamiglasin paper was coated with the obtained pressure-sensitive adhesive at a coating amount of 30 g / m2 (dry weight). ) Was applied using an applicator, and the surface substrate was bonded to form an adhesive sheet. A polypropylene-based synthetic paper (manufactured by Oji Yuka Synthetic Paper Co., Ltd., trade name: SGS80) was used as the surface base material.

Example 2 A surfactant (a nonionic propylene glycol derivative (trade name, manufactured by Kao Corporation)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the blending amount of Homotex PS-90) was changed from 0.5 parts by weight to 5 parts by weight.

Example 3 A surfactant (a nonionic propylene glycol derivative (trade name, manufactured by Kao Corporation)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the blending amount of Homotex PS-90) was changed from 0.5 parts by weight to 20 parts by weight.

Example 4 Instead of the surfactant of Example 1, 5 parts by weight of an anionic polyoxyethylene alkyl ether derivative (trade name: Emal 20C, manufactured by Kao Corporation) was added as a surfactant. A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except for the above.

Example 5 Instead of the surfactant of Example 1, a cationic tetraalkylammonium salt (manufactured by Kao Corporation, trade name: Cotamine 24) was used as the surfactant.
An adhesive sheet was prepared in the same manner as in Example 1 except that 5 parts by weight of P) was used.

Comparative Example 1 Surfactant (non-ionic propylene glycol derivative (trade name, manufactured by Kao Corporation)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the blending amount of Homotex PS-90) was changed from 0.5 part by weight to 0.4 part by weight.

Comparative Example 2 Surfactant (nonionic propylene glycol derivative (trade name, manufactured by Kao Corporation)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the blending amount of Homotex PS-90) was changed from 0.5 part by weight to 30 parts by weight.

Comparative Example 3 A soft vinyl chloride (manufactured by Riken Vinyl Co., Ltd., trade name: Aponyl 70 μm) was used as a base material, and an acrylic ester copolymer and a chloride were used as a self-adhesive resin layer on the base material. A pressure-sensitive adhesive sheet was formed by extruding a resin in which a plasticizer was added to a vinyl graft polymer and laminating the resin.

Example 6 The amount of the crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L) was 1
From 10 parts by weight to 10 parts by weight of a surfactant (a nonionic propylene glycol derivative (manufactured by Kao Corporation, trade name:
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the blending amount of Homotex PS-90) was changed from 0.5 parts by weight to 5 parts by weight.

Comparative Example 4 A compounding amount of a crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L) was 1
The amount of surfactant (nonionic propylene glycol derivative (manufactured by Kao Corporation, trade name: Homotex PS-90)) was changed from 0.5 parts by weight to 5 parts by weight from 0.2 parts by weight to 0.2 parts by weight. A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except for the above.

[Comparative Example 5] The amount of the crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L) was 1
From 15 parts by weight to 15 parts by weight of a surfactant (a nonionic propylene glycol derivative (manufactured by Kao Corporation, trade name:
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the blending amount of Homotex PS-90) was changed from 0.5 parts by weight to 5 parts by weight.

(Evaluation) The following evaluation was performed on the obtained pressure-sensitive adhesive sheet, and the results are shown in Table 1. [Adhesive strength] After removing the release sheet from each adhesive sheet, affix it to the adherend (glass, acrylic, PE),
The adhesive strength was measured according to SZ0237. Units,
gf / 25 mm.

"Adhesive strength after application" After removing the release sheet from each adhesive sheet, the adherend (glass, acrylic, P
E) and left in a 40 ° C environment for 3 days.
The adhesive strength was measured according to Z0237. The unit is gf
/ 25 mm.

[Edge Lift] Each adhesive sheet is 16 mm
It was cut into a size of × 20 mm, affixed to a curved surface of a glass tube having a diameter of 50 mm and a PE tube, left for 1 day in an environment of 22 ° C. and 65% RH, and then visually evaluated for floating peeling according to the following criteria. [Evaluation criteria] ○: No peeling off △: Some peeling off ×: Peeling off

"Weather resistance" [Floating peeling] After removing the release sheet from each pressure-sensitive adhesive sheet, it was attached to an adherend (glass, acrylic, PE).
Using a super weather resistance tester SUV-W11 manufactured by Iwasaki Electric Co., Ltd., the peeling off after 12.3 hours of UV irradiation was visually evaluated according to the following criteria. [Evaluation criteria] ○: No peeling off △: Some peeling off ×: Peeling off

[Adherend Contamination Property] After removing the release sheet from each pressure-sensitive adhesive sheet, the adherend (glass, acrylic, P
E) super weather resistance tester S manufactured by Iwasaki Electric Co., Ltd.
Using UV-W11, adhesive residue (adhered body contamination) on the adherend after 12.3 hours of UV irradiation was visually evaluated according to the following criteria. [Evaluation criteria] ○: no adherend contamination △: slight adherent contamination ×: adherent contamination

"Comprehensive evaluation" ：: Good practicality Δ: Practical level ×: Poor practicality

[0032]

[Table 1]

[0033]

As described in detail above, according to the present invention, the adhesive having a small adhesive strength, good removability, little increase in adhesive strength after application, and excellent adherence to adherends. A sheet was obtained.

Claims (4)

[Claims] 1. A removable pressure-sensitive adhesive sheet comprising a surface substrate provided with a removable pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive constituting the removable pressure-sensitive adhesive layer comprises a (meth) acrylate copolymer as a main component. And further containing 0.5 to 10 parts by weight of a crosslinking agent and 0.5 to 20 parts by weight of a surfactant based on 100 parts by weight of the (meth) acrylate copolymer. Removable adhesive sheet. 2. The removable pressure-sensitive adhesive sheet according to claim 1, wherein the surfactant is a nonionic surfactant. 3. The removable pressure-sensitive adhesive sheet according to claim 1, wherein the crosslinking agent is an isocyanate-based crosslinking agent. 4. The removable pressure-sensitive adhesive sheet according to claim 1, wherein the main monomer of the (meth) acrylate copolymer is 2-ethylhexyl acrylate.