JP3452498B2 - Protective film - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a shadow mask for a cathode ray tube by a two-step etching method. The present invention relates to a protective film for protecting a coating resin layer. 2. Description of the Related Art When a shadow mask for a cathode ray tube is manufactured by a two-stage etching method in which an opening is formed by separately etching from one surface of a thin metal plate, a resist layer on an unetched surface or an already etched surface is manufactured from an etching solution. In order to protect the surface coating resin layer (hereinafter collectively referred to as a resin to be protected), an etching protection film in which an adhesive layer having good removability is provided on one surface of a plastic film which is not attacked by an etching solution is used. ing. These etching protection films are described in, for example, JP-A-63-86877.
And JP-A-4-274132 disclose a protective film made of polyethylene, polypropylene, vinyl chloride or polyester, and JP-A-10-74450 discloses a protective film made of polyethylene terephthalate (PET) resin or the like. A protective film is disclosed. [0003] In each of the above publications, only the type of resin of the plastic film serving as the base layer of the protective film is described. However, the protective film used in the production of the shadow mask for the cathode ray tube has a thickness of the base layer. The handleability of sticking and peeling to shadow mask material (temporary adhesion)
However, the PET film having such a thickness is inferior in the following property, and the etching solution permeates during etching,
There is a possibility that etching may be performed at unnecessary parts. Acrylic pressure-sensitive adhesives are widely used as pressure-sensitive adhesives for protective films made of polyethylene, polypropylene, vinyl chloride, polyester, or the like. There is a possibility that the resin to be protected may be peeled off. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an etching solution which is adhered to a surface to be adhered when a shadow mask for a cathode ray tube is manufactured. The protected resin is not attacked by
Another object of the present invention is to provide a protective film that can be easily peeled off without damaging the resin to be protected. [0006] The protective film of the present invention is obtained by adding a saturated styrene block type thermoplastic elastomer and / or a saturated styrene block type thermoplastic elastomer to a base material layer comprising a polypropylene resin film containing 50% by weight or more of polypropylene. An adhesive layer mainly composed of a styrene-butadiene copolymer is laminated, the thickness is 20 to 50 μm, and the tensile modulus (vertical) is 3000 kg / cm ² or more. is there. [0007] The polypropylene used for the substrate layer is not particularly limited, and includes general homo, random and block type polypropylenes. These may be used alone or as a blend of two or more. Among them, block type polypropylene is preferably used. If the content ratio of polypropylene is 50% by weight or more, a mixture of the above-mentioned polypropylene and another synthetic resin having good compatibility with the above-mentioned polypropylene may be used. Although these other synthetic resins are not particularly limited,
Examples thereof include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and polystyrene. When the base material layer is less than 50% by weight of polypropylene, the flexibility required in conformity to the uneven surface of the protected resin after etching and the temporary adhesion to the CRT shadow mask material including the surface, that is, , It can be easily unwound from the long rolled body to cut out the protective film of the required size, can be stuck on the adhered surface without wrinkling, and after use,
It becomes difficult to provide a well-balanced mechanical strength and hardness that are required to be easily peeled without damaging the protected resin. Incidentally, the polyethylene resin is too flexible, and the temporary adhesion is low and small. The saturated styrenic block type thermoplastic elastomer used for the pressure-sensitive adhesive layer is not particularly limited. For example, styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene- Propylene-styrene block copolymer (SEPS) and the like are exemplified, and the saturated styrene-butadiene rubber is not particularly limited, but examples include hydrogenated styrene-butadiene rubber (SBR). The saturated styrenic block type thermoplastic elastomer and the saturated styrene-butadiene rubber may be used alone or in combination. In addition, only one type of elastomer and rubber belonging to each group may be used, but two or more types may be used in combination. Further, it is mainly composed of a saturated styrene block type thermoplastic elastomer or a saturated styrene-butadiene rubber, and further contains a tackifier resin, an inorganic pigment, an ultraviolet absorber, a light stabilizer, an antioxidant, and the like. You may. The addition amount of the tackifier resin is preferably about 0 to 100 parts by weight based on 100 parts by weight of the elastomer and / or rubber. The means for producing the protective film of the present invention comprises:
Although not particularly limited, for example, a base layer made of the polypropylene resin composition containing 50% by weight or more of polypropylene, and a saturated styrene block thermoplastic elastomer or a saturated styrene-butadiene rubber as a main component. A method of laminating an adhesive layer made of an elastomer composition to be formed by a multilayer co-extrusion molding machine, a method of laminating on a base material layer previously formed into a sheet shape by a laminator, and the like. The protective film of the present invention has a thickness of 20 to 5
0 μm. Further, the thickness of the base material layer is preferably 10 to 45 μm, and the thickness of the adhesive layer is preferably about 3 to 20 μm.
When the thickness of the protective film is less than 20 μm, it is difficult to adhere due to curling or wrinkling when sticking, and the protective film is stretched or peeled off when peeled, resulting in poor handling properties. If the ratio exceeds the above range, the ability to follow the uneven surface of the protected resin after the etching is deteriorated, so that the range is limited to the above range. The tensile modulus of the protective film of the present invention is 3000 to 7000 kg / cm ^{2 in the} resin flow direction.
It is. The tensile modulus is a value measured in accordance with JIS K6781. 3000kg tensile modulus
If it is less than / cm ² , when the film is peeled from the surface adhered to the resin to be protected, the film becomes stretched and becomes difficult to peel. Conversely, if it exceeds 7000 kg / cm ² , the ability to follow the adherend surface will be poor, and the effect of preventing the infiltration of the etching solution may not be exhibited. (Function) Since the protective film of the present invention is configured as described above, the flexibility required in the ability to follow the fine uneven surface of the resin to be protected and the shadow mask for a cathode ray tube including the surface are included. Temporary adhesion to the material, that is,
The protective film of the required size can be easily cut out by unwinding from the long roll, and can be stuck to the surface to be adhered without wrinkling. After use, it can be easily peeled off without damaging the resin to be protected. The required mechanical strength and hardness are provided in a well-balanced manner. (Example 1) A block polypropylene (trade name "BC3" manufactured by Nippon Polychem Co., Ltd.) was used as a base material layer.
M ") and 25 parts by weight of low-density polyethylene (trade name" Mirason 12 "manufactured by Mitsui Chemicals, Inc.), and a hydrogenated styrene-butadiene-styrene block copolymer (Shell Chemical Co., Ltd.) as an adhesive layer (Claton G1657), 100 parts by weight of a tackifier resin (Arakawa Chemical Co., Ltd., trade name "Alcon P10")
0 ") and 0.5 parts by weight of an antioxidant (trade name" Irganox 1010 "manufactured by Ciba-Geigy Co., Ltd.), and the base material layer 30 is formed by a T-die coextrusion method.
A protective film was prepared so as to have a thickness of 10 μm and an adhesive layer of 10 μm. Example 2 Instead of the adhesive layer of Example 1,
Hydrogenated styrene-butadiene rubber (manufactured by JSR,
A protective film was produced in the same manner as in Example 1 except that trade name “Dynallon 1321P”) was used. (Comparative Example 1) The thickness of the substrate layer of Example 1 was set to 5
A protective film was produced in the same manner as in Example 1, except that the thickness was changed to 8 μm and the thickness of the adhesive layer was changed to 12 μm. (Comparative Example 2) Instead of the base material layer of Example 1,
A protective film was produced in the same manner as in Example 1, except that only low-density polyethylene (trade name “Milason 12” manufactured by Mitsui Chemicals, Inc.) was used. (Comparative Example 3) Instead of the base material layer of Example 1,
High-density polyethylene (trade name "L447" manufactured by Asahi Kasei Corporation)
0 ") alone, except that only a protective film was used. In order to evaluate the obtained protective films of Examples 1 and 2 and Comparative Examples 1 to 3, the initial adhesive strength of the shadow mask material to the resist layer and the resin layer coated on the etched surface, and the following etching treatment conditions: The adhesive strength after the treatment and the sticking performance to the resin surface to be protected were evaluated. The evaluation results are shown in Table 1. The adhesive strength was measured in accordance with JIS Z 0237, and the sticking performance was sticking (wrinkles, streaks, presence or absence of etching liquid), peeling (whether or not the protected surface was damaged, elongation of the protective film). ) Was based on a sensory test of three inspectors who were skilled in the work. [Etching treatment conditions] Resist surface: treated with a treatment solution A adjusted to pH = 1 by adding hydrochloric acid to a 10% by weight aqueous solution of ferric chloride, treated at 75 ° C. for 5 minutes, washed with water for 3 minutes, Sodium hydroxide 10
95 ° C. with a processing solution B consisting of a weight% aqueous solution (pH = 12)
It was treated for 5 minutes, washed with water and dried at 100 ° C for 3 minutes. Protective resin surface: treated with treatment liquid A at 75 ° C. for 15 minutes, washed with water for 3 minutes, and dried. [Table 1] As is clear from Table 1, the protective films of Examples 1 and 2 according to the present invention both have good initial adhesion to the resin surface to be protected and adhesion after the etching treatment, and adhere to the surface to be adhered. Thus, the surface was protected, and the sticking performance was extremely good. On the other hand, the protective film of Comparative Example 1 did not adhere to the surface to be adhered, and the protective function of the surface was deteriorated due to the penetration of the etching solution. All were too flexible and had extremely poor sticking performance. The protective film of the present invention has the flexibility required in the ability to follow the fine uneven surface of the resist and the protective resin after etching, and the provision of a temporary film for the cathode ray tube shadow mask material including the surface. Adhesiveness, that is, the protective film of the required size can be easily cut out by rewinding from the long wound body, can be stuck to the adhered surface without wrinkling, and after use, the resist and the protective resin on the adhered surface can be removed. A well-balanced mechanical strength and hardness that are required to be easily peeled without damage are provided. Therefore, the surface to be adhered in the etching process of the shadow mask material for the cathode ray tube is sufficiently protected.

Claims (1)

(1) In forming an opening in a thin metal plate by a two-step etching method, a resist layer on a non-etched surface or a resin layer coated on an etched surface is protected from an etchant. A protective film, wherein the protective film is mainly composed of a saturated styrene block type thermoplastic elastomer and / or a saturated styrene-butadiene rubber in a base layer made of a polypropylene resin film containing 50% by weight or more of polypropylene. A protective film comprising a laminated adhesive layer having a thickness of 20 to 50 μm and a tensile modulus in the resin flow direction of 3000 to 7000 kg / cm ² .