JPH059442A - Self-adhesive sheet excellent in weather resistance - Google Patents

Abstract

PURPOSE:To obtain the title sheet excellent in weather resistance and capable of being used outdoors for a long time by forming a specified ultraviolet- screening layer on that surface of a support which has no pressure-sensitive adhesive applied. CONSTITUTION:A transparent ultraviolet-screening layer comprising a resin (e.g. acryl rubber) and an inorganic pigment (e.g. ZnO) desirably having a particle diameter of below 0.1mum is formed on that side of a support (e.g. PE film) which has no self-adhesive (e.g. acryl rubber) applied.

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, tape or film (hereinafter referred to as a pressure-sensitive adhesive sheet) having excellent weather resistance.

[0002]

2. Description of the Related Art Adhesive sheets are used for construction, for the purpose of surface protection.
It is used in various fields such as home appliances, home appliances / OA, and automobiles. Particularly when used outdoors for a long period of time such as in construction, it is necessary to use an adhesive sheet that has been subjected to ultraviolet ray resistance measures in order to prevent deterioration due to sunlight, and various countermeasure methods shown below have been proposed so far. (1) Addition of an ultraviolet absorber to the adhesive. (2) Addition of an ultraviolet absorber to the support (JP-A-58-220139 and JP-A-61-11)
1341 and JP-A-2-251590).
(3) Formation of an ultraviolet absorbing layer on the surface of the support (JP-A-58)
No. 29664, No. 62-263045, No. 2-24140, and No. 57-187.
No. 248, and Japanese Patent Laid-Open No. 2-170828)

[0003]

However, in order to develop sufficient ultraviolet absorption by adding an ultraviolet absorber, it is necessary to use a relatively large amount, and therefore bleed-out on the adhesive or the back surface of the support. Problem arises. In addition, since there is a problem such as a decrease in adhesion between the pressure-sensitive adhesive and the support and coloring due to the addition, it cannot be added in a large amount, and a sufficient effect of ultraviolet absorption cannot be expected. Further, since the ultraviolet absorber is an organic compound, it is deteriorated, volatilized and decomposed by ultraviolet rays or heat, and it is difficult to maintain stable characteristics for a long period of time.

[0004]

The present inventors have completed the present invention as a result of intensive studies, experiments, and studies for solving the problems such as bleeding out that are seen in the prior art. That is, the present invention relates to a pressure-sensitive adhesive sheet characterized in that a transparent ultraviolet blocking layer made of a resin and an inorganic pigment is provided on the surface of a support on the side not coated with a pressure-sensitive adhesive. The ultraviolet blocking layer used in the present invention comprises a mixture of 10 to 90 parts by weight of a resin and 90 to 10 parts by weight of an inorganic pigment having a particle size of less than 0.1 μm.

Examples of the resin include acrylic resin, alkoxide resin, amino resin, nitrocellulose, polyester resin, phenol resin, ketone resin, and the like, and acrylic resin which itself has excellent weather resistance is preferably used. As inorganic pigments, white pigments (titanium oxide, zinc oxide, lithopone, lead white), extender pigments (chalk, barium sulfate, alumina white, silica white, clay), black pigments (carbon black, lamp black, iron black, diamond) black),
Red pigments (Bengala, vermilion, cadmium red, cadmium mercury red, chrome vermillion, red lead, lake red 4R,
Lake Red C, Woochan Red, Quinacridone Red, Rose Red, Madder Lake, Bon Maroon, Brilliant Carmine, Western Vermilion, Yellow Pigment (Yellow Lead, Dicyclochrome, Cadmium Yellow, Ocher, Titanium Yellow, Hansa Yellow, Benzicine Yellow) ), Green pigments (chrome green, chromium oxide, viridian, phthalocyanine green, green gold, acid green gold), blue pigments (dark blue, ultramarine, phthalocyanine blue, Victoria blue lake, peacock blue lake), purple pigments (manganese bio red, Cobalt violet red), metal powder pigments (aluminum powder, bronze powder) and the like.

Among these, zinc oxide, titanium oxide and the like having high ultraviolet ray reflection (absorption) properties are preferably used, and in order to ensure transparency, the particle size is preferably 0.001 to 0.1 μm. The ultraviolet blocking layer is used in a mixture of 10 to 90 parts by weight of a resin and 90 to 10 parts by weight of an inorganic pigment. When the amount of the inorganic pigment exceeds 90 parts by weight, the ultraviolet blocking layer moldability and the adhesion to a support are lowered. If the amount is less than 10 parts by weight, the ability of reflecting (absorbing) ultraviolet rays is deteriorated. A resin and an inorganic pigment are essential for the ultraviolet blocking layer, and a crosslinking agent, a catalyst and the like may be added. If the thickness of the ultraviolet blocking layer is 1 μm or more, it can be freely adjusted within the range where the transparency is not lost. The above-mentioned composition is usually applied by dissolving and diluting it in a solvent and coating and drying it on the surface of the support.

Next, as the support used in the present invention,
Polyesters such as polyethylene terephthalate and polybutylene terephthalate, aliphatic or aromatic polyamides, polyolefins such as polyethylene and polypropylene, synthetic resin films made of polystyrene, polycarbonate, polyvinyl chloride, polyvinylidene chloride, and semi-synthetic resin films such as cellulose acetate. ,
Examples thereof include synthetic resin films of the same type, synthetic resin films and semi-synthetic resin films, and synthetic resin films and / or laminate films of semi-synthetic resin films and paper. Further, a light stabilizer (ultraviolet absorber, quencher, etc.), antioxidant and the like may be added to the support, and the weather resistance is further improved. In order to obtain stronger adhesion between the support and the ultraviolet blocking layer, surface treatment is performed by a general method,
A support having improved wettability is preferably used. The pressure-sensitive adhesive used in the present invention is not particularly limited, but an acrylic acid ester-based polymer or a polyisobutylene-based one is particularly preferable in view of its use.

[0008]

The technical point of the weather resistant support for pressure-sensitive adhesive sheets of the present invention is that a layer comprising an inorganic pigment is provided on the surface of the support. Inorganic pigments are different from organic UV absorbers,
It has no pollution properties due to bleed-out, is less likely to undergo alteration, volatilization, and decomposition compared to organic systems, and is extremely stable against ultraviolet rays and heat, so stable characteristics can be maintained over a long period of time. It is considered that by providing the ultraviolet blocking layer on the outermost surface of the pressure-sensitive adhesive sheet, the ultraviolet deterioration of the support and the pressure-sensitive adhesive can be suppressed, and the weather resistance of the pressure-sensitive adhesive sheet can be dramatically improved. As a result, a pressure-sensitive adhesive sheet that can be used for outdoor applications requiring weather resistance can be obtained.

[0009]

EXAMPLES The present invention will be described below with reference to examples.
The scope of the invention is in no way limited by these examples. However, all parts are parts by weight.

Example 1 Acrylic rubber (Q-1851, manufactured by Nippon Carbide Co., Ltd.)
(EA / 2-EHA / HEMA)) 70 parts, ultrafine particles Z
nO (Sumitomo Cement Co., Ltd., ZnO-100 particle size 0.
005-0.015 μm) 30 parts Trifunctional aliphatic isocyanate (Sumitomo Baiurethane Co., Ltd., Sumidule N) 1 part composition 10 wt% toluene solution UV blocking agent 60 μm thick double-sided corona The treated polyethylene film was coated on one side so that the thickness after drying was 4 μm to form an ultraviolet blocking layer, and an acrylic rubber (Toa Paint Co., Ltd.) was formed on the opposite side of the polyethylene film.
Manufactured by XE-2644 (BA / AN / HEA)) in a 6 wt% toluene solution was applied to give a thickness of 3 μm after drying to obtain a pressure-sensitive adhesive sheet. The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Example 2 The same as Example 1 except that the ultrafine particles ZnO of the ultraviolet blocking layer were changed to TiO ₂ (Sakai Chemical Industry Co., Ltd., particle size 0.005 to 0.015 μm). The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1. Ultrafine ZnO particles for the UV blocking layer are general ZnO (Sakai Chemical Industry Co., Ltd., No. 1, particle size 0.5 μm)
The same as Example 1 except that it was changed to. The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Comparative Example 1 Acrylic rubber (XA-264 manufactured by Toa Paint Co., Ltd.)
The 6% by weight toluene solution pressure-sensitive adhesive of 4) was applied to one side of the corona-treated surface of a polyethylene film having a thickness of 60 μm so that the thickness after drying was 3 μm to obtain a pressure-sensitive adhesive sheet. The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Comparative Example 2 Acrylic rubber (manufactured by Nippon Carbide Co., Q-1851)
(EA / 2-EHA / HEMA)) 70 parts, benzotriazole-based UV absorber (Tinubin 326 manufactured by Ciba-Geigy Co., Ltd.) 30 parts, trifunctional aliphatic isocyanate (Sumitomo Bayurethane Co., Ltd., Sumidule N) 1 Composition of 10 parts by weight of a toluene solution of 10% by weight of an ultraviolet blocking agent having a thickness of 6
A 0 μm double-sided corona-treated polyethylene film was coated on one side so that the thickness after drying was 4 μm, and an ultraviolet blocking layer was formed. Acrylic rubber (Toa Paint Co., Ltd., XE -2644
A (6% by weight) toluene solution of (BA / AN / HEA) was applied to give a pressure-sensitive adhesive sheet so that the thickness after drying would be 3 μm. The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Comparative Example 3 Same as Comparative Example 2 except that 95 parts of acrylic rubber (Q-1851) and 5 parts of benzotriazole type ultraviolet absorber (Tinuvin 326) were used. The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Comparative Example 4 A polyethylene film having a light stabilizer added thereto and having a thickness of 60 μm (light stabilizer: hindered amine type quencher (Ciba-Gaigi Co., Ltd.)
(Tinubin 622LD), a phenolic antioxidant (Ciba-Geigy Co., Ltd., Irganox 1070), and 100 parts of polyethylene, 5 parts of a light stabilizer was added to one side of the corona-treated surface with the same adhesive as in Example 1. It was applied and used as an adhesive sheet. The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Comparative Example 5 Acrylic rubber (XE-264 manufactured by Toa Paint Co., Ltd.)
4) A 6 wt% toluene solution adhesive consisting of 100 parts and 5 parts of a benzotriazole type ultraviolet absorber (Tinubin 326, manufactured by Ciba-Geigy Co., Ltd.) was applied in the same manner as in Example 1 to obtain an adhesive sheet. The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Comparative Example 6 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the ultrafine ZnO particles in Example 1 were changed to general ZnO (particle size 0.5 μm). The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

[0018]

[Table 1] Test content 1) The bleed-out pressure-sensitive adhesive sheet was allowed to stand for 2 months under each condition of room temperature of 65 ° C., 40 ° C. and 90% RH, and it was observed whether the ultraviolet blocking agent or the light stabilizer was bleed out. ○: No bleed out ×: With bleed out 2) Roll-press the weather resistant adhesive sheet onto an Al plate and apply the sunshine weather meter (WEL-SUN-H manufactured by Suga Test Instruments Co., Ltd.)
C type), the atmosphere: 43 ° C., 60% RH (black panel temperature: 63 ° C.), rainfall: 12 min / h, treatment time: 800 h, and the adhesive is transferred to an Al plate during peeling. I observed what I was wearing. ○… No transfer is observed. Δ ... Transferring is recognized in the range of 20% or less of the surface area of the Al plate. X to Δ ... Transferring is recognized in the range of 20 to 50% of the surface area of the Al plate. X ... Transferring is recognized in the range of 50% or more of the surface area of the Al plate. The results are indicated by the symbols above.

[0020]

The weather-resistant support for pressure-sensitive adhesive sheets of the present invention comprises
By providing an ultraviolet blocking layer on the back surface of the support using an inorganic pigment that does not bleed out, deterioration of the support and the adhesive due to ultraviolet rays can be significantly suppressed, and remarkable weather resistance can be imparted to the adhesive sheet. It can be used outdoors for a long time.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yutaka Yamaguchi             Hitachi Chemical, 1500 Ogawa, Shimodate City, Ibaraki Prefecture             Shimodate Research Institute, Industry Co., Ltd.

Claims (3)

[Claims] 1. A pressure-sensitive adhesive sheet, comprising a transparent UV-shielding layer comprising a resin and an inorganic pigment provided on the surface of the support on the side not coated with the pressure-sensitive adhesive. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the inorganic pigment has a particle size of less than 0.1 μm. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the inorganic pigment is zinc oxide or titanium oxide.