JPH0962188A - Self-adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-adhesive sheet having excellent weather resistance and excellent follow-up property for various bodies to be adhered and good productivity without causing contamination due to a plasticizer or decrease in the adhesion strength of an adhesive. SOLUTION: One surface of an ETFE film 1 is subjected to activation treatment, and a color layer 3 is laminated on the activated surface 2 of the film 1. The color layer 3 consists of an acryl resin having UV-absorbing groups in the molecule, an acryl resin having no UV-absorbing group in the molecule, and a coloring agent. Further, an adhesive layer 4 and a release paper 5 are successively laminated on the color layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a colored pressure-sensitive adhesive sheet which is cut out into pictograms or the like and attached to various adherends for use in various displays and decorations.

[0002]

2. Description of the Related Art An adhesive sheet in which a colored synthetic resin sheet having an adhesive layer on one side is laminated on a release paper is used to cut out pictograms and the like using a cutting machine automatically controlled by a computer, and the pictograms and the like are adhered. It is transferred to and various display and decoration are performed.

The above-mentioned colored adhesive sheet has weather resistance, stain resistance, and
It is required to have excellent followability to adherends and excellent color. A sheet made of a soft vinyl chloride resin is suitable as a material having such characteristics, and a sheet manufactured by a calendar method or a casting method occupies the mainstream.

Further, Japanese Patent Laid-Open No. 1454853/1992 discloses that
A tetrafluoroethylene-ethylene copolymer film (hereinafter referred to as "ETFE film") to which an ultraviolet absorber is added is subjected to corona discharge treatment, and a colored resin in which various pigments are dispersed using a solvent-soluble fluororesin as a binder There is described a marking film in which a colored layer is formed by coating or printing, and an adhesive layer and a releasable substrate are laminated on the colored layer.

[0005]

However, the former soft vinyl chloride resin film usually contains a large amount of a plasticizer and a stabilizer, and since the resin is exposed on the outermost surface, the film is formed over a period of days. There is a problem in that the plasticizer and the like bleed out, the surface of the pressure-sensitive adhesive sheet is contaminated, and the adhesive strength of the pressure-sensitive adhesive decreases.

The latter publication is the same as the above ET.
The ultraviolet absorber added to the FE film bleeds out and is washed away, and the ultraviolet shielding effect does not last for a long time. Further, there is a problem that the solvent-soluble fluororesin and the adhesive have low adhesiveness and are easily peeled off. Further, when this colored sheet is stretched and applied, there is a problem in that the followability of the colored layer to the ETFE film is unstable, and if the colored layer is hard, the colored layer is broken.

The present invention solves the above-mentioned problems of the prior art, is excellent in weather resistance, and can follow adherends of various shapes without causing contamination due to the influence of a plasticizer and reduction of the adhesive strength of the adhesive. It is intended to provide a pressure-sensitive adhesive sheet having excellent properties.

[0008]

Means for Solving the Problems The pressure-sensitive adhesive sheet of the present invention comprises:
Acrylic resin made by copolymerizing acrylic monomer with UV absorbing group in the molecule with other acrylic monomer on the activated surface of fluororesin film with one side activated, UV absorption in the molecule A colored layer composed of an acrylic resin having no functional group and a colorant is laminated, and an adhesive layer and release paper are sequentially laminated on the surface of the colored layer.

As the fluororesin film, tetrafluoroethylene-ethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene- Examples thereof include films such as hexafluoropropylene copolymer (FEP). The thickness of the fluororesin film is 20 to 2
The thickness is preferably in the range of 00 μm, more preferably 50 to 100 μm. If this thickness is less than 20 μm, the film becomes stiff and the workability of attachment becomes poor, and if it is thicker than 200 μm, the conformability to curved surfaces becomes poor, and it is clearly discriminated that the film is attached and it is aesthetically pleasing. Not preferable.

Since the surface of the fluororesin film is very low, it is necessary to activate this one surface. The activation treatment is generally performed by corona discharge treatment, and the activity by corona discharge treatment is preferably such that the surface tension of the film is about 30 to 50 dyn / cm.

The colored layer used in the present invention comprises an acrylic resin having an ultraviolet absorbing group in the molecule, an acrylic resin having no ultraviolet absorbing group in the molecule, and a colorant. The acrylic monomer having an ultraviolet absorbing group is, for example, one having an ultraviolet absorbing group at the terminal such as ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth) acrylate. Examples of the ultraviolet absorbing group include a benzophenone group, a benzotriazole group, a cyanoacrylate group, and modified groups thereof.

Acrylic resins having an ultraviolet absorbing group in the molecule as described above are absorbed by ultraviolet rays by an esterification reaction of methacrylic acid or acrylic acid with an alcohol having an ultraviolet absorbing group such as a benzophenone group or a benzotriazole group. It can be obtained by preparing an acrylic monomer having a group and copolymerizing it with another acrylic monomer. The acrylic resin preferably has a molecular weight of 30,000 to 500,000.

The acrylic resin having no ultraviolet absorbing group in the molecule is a copolymer of methacrylic acid ester and acrylic acid ester and has a molecular weight of 20 to 50.
It is preferable that the Tg is -50 to 15 ° C. The mixing ratio of the acrylic resin having an ultraviolet absorbing group in the molecule and the acrylic resin having no ultraviolet absorbing group in the molecule is preferably 10: 1 to 1:10, and a more preferable ratio is It is 1: 1 to 1: 3. When the amount of the acrylic resin having an ultraviolet absorbing group in the molecule is less than the above ratio, the ultraviolet ray shielding effect does not last for a long time, and when the amount is more than the above ratio, the acrylic resin having the ultraviolet absorbing group has a high Tg. However, the above range is preferable because it becomes hard and the followability with the film and the adhesiveness deteriorate.

In the present invention, since the colored layer contains an acrylic resin having an ultraviolet absorbing group, the weather resistance is permanent due to the ultraviolet absorbing action of the acrylic resin. Further, unlike the case where the ultraviolet absorber is used, the ultraviolet absorber does not bleed out from the resin. Therefore, the adhesion between the colored layer and the corona-discharge-treated fluororesin film is significantly improved, the followability of the colored layer is excellent, and the colored resin peels or breaks even when the fluororesin film stretches or bends during construction. You can avoid doing it.

The acrylic resin having an ultraviolet absorbing group in the molecule and the acrylic resin having no ultraviolet absorbing group in the molecule are binders for the colorant, and the colorant is dispersed in the mixed acrylic resin. To be done. As the colorant, an organic pigment or an inorganic pigment having excellent heat resistance and weather resistance is used. Examples of organic pigments include perylene, isoindoline, polyazoquinacridone, and cyanine. Inorganic pigments include white pigments (titanium oxide, zinc oxide, lithopone, etc.), black pigments (carbon black, etc.), red pigments (red iron oxide, cadmium red, lake red C, quinacridone red, mudder lake, etc.), yellow pigments (yellow lead). , Dicyclomate, cadmium yellow,
Titanium yellow, etc.), green pigments (chrome green, chromium oxide, pyridian, etc.), and various other pigments can be used. 1 to 60 parts by weight of these organic or inorganic pigments are added to 100 parts by weight of the mixed acrylic resin.

In order to laminate the colored layer on the activation-treated surface of the fluororesin film, the mixed acrylic resin in which the above colorant is dispersed is applied by various roll coaters, knife coaters or the like which have been conventionally used, or It may be provided by printing such as gravure printing and offset printing. The thickness of the colored layer is preferably 5 to 100 μm, more preferably 10 to 50 μm. If it is thinner than 5 μm, good coloring property or hiding property cannot be imparted, and 1
If it is thicker than 00 μm, the entire sheet becomes thicker, so that the followability to a curved surface is deteriorated and it is clearly discriminated that it is attached, which is not aesthetically preferable.

[0017]

Embodiments of the pressure-sensitive adhesive sheet of the present invention will be described below. (Example 1) ETFE film (Asahi Glass Co., Ltd., thickness 50)
Corona discharge treatment was applied to one side of the surface of the glass substrate (μm) so that the surface tension was 45 dyn / cm. A weight ratio of a copolymer of 50% methyl acrylate and 50% methyl methacrylate having a benzophenone group at the molecular end (molecular weight 200,000) and a methacrylic acid-acrylic acid ester-styrene copolymer (molecular weight 300,000) is 4: The binder was prepared by mixing in 1.

To 100 parts by weight of the solid content of the above binder,
A coloring resin containing 15 parts by weight of cyanine blue (trade name "VT-51", manufactured by Dainichiseika Co., Ltd.) as a coloring agent was applied to the corona discharge treated surface of the ETFE film with a thickness of 15 µm using a knife coater. A colored layer was formed.
After that, an acrylic pressure-sensitive adhesive is applied to the colored layer surface so that the thickness after drying is 30 μm and dried to form a pressure-sensitive adhesive layer,
A release paper was laminated on the pressure-sensitive adhesive layer surface.

FIG. 1 is a sectional view showing an embodiment of the pressure-sensitive adhesive sheet of the present invention obtained as described above, 1 is an ETFE film, 2 is a corona discharge treated surface, 3 is a colored layer, 4 is an adhesive layer, 5 is a release paper.

Example 2 Instead of the copolymer of methyl acrylate having a benzophenone group and methyl methacrylate (molecular weight 200,000), a copolymer of methyl acrylate having a benzotriazole group and methyl methacrylate (molecular weight 100,000) was used. The same pressure-sensitive adhesive sheet as in Example 1 was used except that

Example 3 A copolymer of 50% methyl acrylate and 50% methyl methacrylate having a benzophenone group at the molecular end (molecular weight 200,000) and a methacrylic acid-acrylic acid ester-styrene copolymer (molecular weight 30) The same pressure-sensitive adhesive sheet as in Example 1 was used, except that the weight ratio with the same was 8: 1.

(Example 4) Instead of 15 parts by weight of cyanine blue (manufactured by Dainichiseika Co., Ltd., trade name "VT-51") as a coloring agent, titanium oxide (manufactured by Dainichiseika Co., Ltd., trade name "VT-") was used.
771 ") The same pressure-sensitive adhesive sheet as in Example 1 was used except that 35 parts by weight was used.

(Comparative Example 1) A pressure-sensitive adhesive sheet similar to that of Example 1 was used except that a solvent-soluble fluororesin (vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer) was used as the binder of the colorant. .

Comparative Example 2 50% methyl acrylate and 50% methyl methacrylate having a benzophenone group at the molecular end were used without using a methacrylic acid-acrylic acid ester-styrene copolymer (molecular weight 300,000) as a constituent resin of the binder. The same pressure-sensitive adhesive sheet as in Example 1 was prepared except that only the copolymer (having a molecular weight of 200,000) was used.

(Comparative Example 3) A methacrylic acid-acrylic acid ester was used as a binder resin without using a copolymer of 50% methyl acrylate and 50% methyl methacrylate having a benzophenone group at the molecular end (molecular weight 200,000). -The same pressure-sensitive adhesive sheet as in Example 1 was used except that only a styrene copolymer (molecular weight 300,000) was used.

Performance Evaluation (1) Weather Resistance Test 144 hours (equivalent to 3 years), 216 hours (equivalent to 5 years), 360 using an exposure tester (Dainippon Plastics Co., Ltd., trade name "Super UV Tester") A color difference meter (manufactured by Nippon Denshoku Co., Ltd.,
It was measured under the trade name “Σ-300”). (2) Measurement of Adhesion between Fluororesin Film and Adhesive Layer A polyethylene terephthalate substrate coated with a primer (manufactured by Nippon Shokubai Co., Ltd., trade name “NK-380”) and dried was used as an adherend. The pressure-sensitive adhesive sheets of Examples and Comparative Examples were attached to the adherends, left at 23 ° C. for 24 hours, and then peeled by T-type at a pulling speed of 500 mm / min to measure the peeling force. In this measurement, the value at which the adhesive layer and the colored layer were completely peeled off at the time of peeling was defined as the anchor force. (3) Follow-up property The adhesive sheets of Examples and Comparative Examples were 5% and 1%, respectively.
The state of the colored layer when stretched by 0% and 30% was observed and expressed in the following five stages. 5: Completely followed 4: Partially whitened 3: Significantly whitened 2: Partially peeled fluororesin film and colored layer 1: Most peeled fluororesin film and colored layer It shows in Table 1.

[0027]

[Table 1]

As is apparent from Table 1, the colored layers of Examples 1 to 4 have excellent weather resistance and adhesion to the fluororesin film, and the colored layers can completely follow the elongation of the fluororesin film. . On the other hand, it can be seen that the comparative examples are all inferior in performance.

[0029]

The pressure-sensitive adhesive sheet of the present invention has the above constitution,
The acrylic resin having a UV-absorbing group in the molecule as a coloring resin has the UV-absorbing action, whereby the weather resistance is permanent.
Further, it is excellent in weather resistance, excellent in conformability to adherends of various shapes and good in productivity, without causing contamination due to the influence of the plasticizer or reduction in adhesive strength of the adhesive. Furthermore, the adhesion between the colored resin and the corona-discharge-treated fluororesin film is excellent, and peeling or breakage of the colored resin can be avoided even if the fluororesin film stretches or bends during construction.

[0030]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of the pressure-sensitive adhesive sheet of the present invention.

[Explanation of symbols]

 1: ETFE film 2: corona discharge treated surface 3: colored layer 4: adhesive layer 5: release paper

Claims (1)

[Claims] 1. An acrylic resin obtained by copolymerizing an acrylic monomer having an ultraviolet absorbing group in the molecule with another acrylic monomer on the activation surface of a fluororesin film having one surface activated. A pressure-sensitive adhesive sheet characterized in that a colored layer comprising an acrylic resin having no ultraviolet absorbing group in the molecule and a colorant is laminated, and an adhesive layer and a release paper are sequentially laminated on the surface of the colored layer.