JPS605464B2 - Surface protection film - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a surface protection film suitable for use in preventing dust from adhering to or damaging metal plates, synthetic resin-coated metal plates, synthetic resin plates, glass plates, etc. .

Conventional surface protection films consist of a base material layer such as vinyl chloride or polyethylene, and an adhesive layer (hereinafter referred to as the temporary adhesion layer) made of polyisobutylene rubber, natural rubber, or acrylic rubber with a tackifier added. Among them, those using acrylic rubber have relatively little change in adhesive strength over time even when exposed outdoors, so they can be used outdoors and are advantageous. However, surface protection films that have a temporary adhesion layer that uses an adhesive generally have the disadvantage that they tend to leave so-called adhesive residue on the surface of the adherend when the film is temporarily attached to the adherend and then peeled off. Currently, two-layer films based on modified polyolefins such as ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) or metal ion crosslinked product of ethylene-methacrylic copolymer (hereinafter abbreviated as ionomer) are used. It started to be done.

Surface protection films using the above-mentioned modified polyolefin as a temporary adhesion layer can be applied at room temperature depending on the adherend, and can also be used on rough-surfaced plates, and those with surfactants added have strong adhesive properties when heated. Another advantage is that the increase is relatively small. However, on the other hand, this 1-2
If exposed outdoors for a week, it would be difficult to remove, making it unsuitable for outdoor use. The present invention has been made to solve these drawbacks, and its gist is as follows:
In a surface protection film composed of a base layer made of a thermoplastic resin and a temporary adhesion layer which is a composition mainly composed of a modified polyolefin, at least the temporary adhesion layer has an antioxidant function and has a hydrophobic group. A surface protection film characterized by containing a compound and an ultraviolet absorber.

The thermoplastic resin used in the base layer of the present invention is not particularly limited, but polyethylene, polypropylene, polyvinyl chloride, polyester, polycarbonate, and mixtures thereof can be used.

Further, in some cases, commonly used antioxidants, ultraviolet absorbers, lubricants, antistatic agents, etc. may be added thereto. The thickness of the base material layer is preferably 0.01 to 0.2 mm. In addition, as the residual polyolefin used for the temporary adhesive layer, EVA, saponified EVA, ethylene-ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl acetate-methacrylic acid turbolimer, acid graft modified polyethylene, or Ionomers and the like can be used alone or in combination, but EVA containing 10 to 70% by weight of vinyl acetate is particularly suitable. Furthermore, for the temporary adhesion layer, terbene-based resin, coumaron-based resin, etc.
Rosin grand resin
May be added.

Next, as a compound having an antioxidant function and a hydrophobic group, distearyl 3,3-thiodipropionate,
Alternatively, peroxide decomposition type antioxidants such as dilauryl 3,3'-monothiodibropionate are effective, and these are added in an amount of 0.05 to 5% by weight, preferably 0.1 to 1% by weight, based on the resinous polyolefin. It has been found that by adding % by weight, the increase in adhesive strength of the temporary adhesion layer during outdoor exposure is significantly suppressed.

In addition, as ultraviolet absorbers, penzophenones such as 2,4-di/-hydroxybenzophenone, 2-hydroxy-4-toxybenzophenone, and 2-hydroxy-4-n-octoxybenzophenone are used. or 2 (
2'-Hydroxy3,5-di-t-amylfenyl)
Penzotriazole, 2(2-hydroxy-3't)
-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2(2'-hydroxy4'-n-octoxyphenyl)penzotriazole, 2-(2'-hydroxy5'-methylphenyl)penzotriazole, etc. Penzotriazole-based compounds can be used.

The amount of the ultraviolet absorber added is preferably 0.05 to 10% by weight, particularly 0.1 to 3% by weight, based on the modified polyolefin.

The UV absorber may be a UV absorber other than a normal UV absorber, such as 2.5bis[5'-t-phthylbenzoxalyl'2)]thiophene, which does not require a fluorescent brightener or transparency. In some cases, carbon black may also be used.

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Using the inflation extrusion device shown in Fig. 1, 2.50
Low-density polyethylene (density 0.919/lump MI = 7) that forms the base material layer is introduced from the hopper 14 of the extruder 19, introduced into the tube hole 3 from the tube hole entrance neck 5, and placed at the tip of the screw S. extrude

On the other hand, in the hopper turtle 8 of the 150 extruder 20, EVA (VA
:28% by weight, MI:6) for 10 parts by weight of distearyl-393-diisopropionate and 2(2'
- Hydroxy-3-t-butyl-5'-methylsuenyl)-5-chlorobenzotriazole (10 parts by weight) each containing 3 phr of the same EVA masterbatch were mixed, and the screw 1
At the tip of the screw i, a low density polyethylene layer is coated on the outer surface of the screw i, and after mixing the two in the boundary area by rotating the mixing head 5, the adapter 7 and the floc 8. A low-density polyethylene layer extruded as a blown film through a nose 9, a conical part 10, a spider part 11 and a die rib 12, and consisting of a base layer and a temporary adhesion layer including an intermediate layer mixed with the components of the base layer; Density Polyethylene/EVA Composition A surface protection film was prepared with each EVA composition having a thickness of about 25 cm and 20 r/2 cm.The adhesive properties of the film are as shown in Table 1.Example 2 The formulation and extrusion method of the material layer and the temporary adhesive layer were the same as in Example 1, and a surface protection film was produced that consisted of two layers, the base material layer and the temporary adhesive layer each having a thickness of 4 mm and 2 layers.

The adhesive properties of the film are shown in Table 1. Example 3 Polypropylene (density 0.90/, M
A surface protection film was produced in the same manner as in Example 2, except that I=8) was used, and the surface protection film consisted of two layers, the base layer and the temporary adhesive layer having a thickness of 40 mm and 20 mm, respectively.

Table 1 shows its adhesive properties. Example 4 A low density polyethylene layer, a low density polyethylene/EVA composition, and an EVA composition were prepared in the same manner as in Example 1 except that distearyl-3,3-diisopropionate was changed to dilaryl-3,3 dipropionate. A surface protection film including a temporary adhesion layer and an intermediate layer each having a thickness of about 2 layers/2 layers/20 layers was obtained.

Table 1 shows its adhesive properties. Comparative example 1EVA(V
A=28%, MI=6) with GAF which is estyl phosphate.
The composition of the temporary adhesive layer was that AC-RM-410 (anionic surfactant, manufactured by Toho Chemical Co., Ltd.) was added at a final concentration of 0.2 phr.Other than that, the composition of the temporary adhesive layer was the same as in Example 2, and the base material layer and temporary adhesive layer were A surface protection film consisting of two layers, each with a thickness of 40 mm, was made.

The adhesive properties of this are shown in Table 1. Comparative Example 2 In the temporary adhesion layer, 4,4-thiobis(6-t-butyl)- was used instead of distearyl-3,3-diisopropionate.
A surface protection film was prepared in the same manner as in Example 2, except that a phenolic antioxidant consisting of 3-methylphenol was added at a final concentration of 0.3 phr, and the thickness of the base layer and temporary adhesion layer were 40 mm and 2 mm, respectively. made.

Its adhesive properties are shown in Table 1. As is clear from Examples 1 to 4 in Table 1, the surface protection film according to the present invention exhibits a small increase in strength, that is, adhesive strength, not only when heated but also when irradiated with ultraviolet rays.

On the other hand, in the case of Comparative Example 1, the adhesive strength does not increase during heating, but increases rapidly to 700/25 side when irradiated with ultraviolet rays. Furthermore, in Comparative Example 2, a compound having an antioxidant function but not containing a hydrophobic group was used in combination with an ultraviolet absorber, and the adhesive strength increased significantly both during heating and when irradiated with ultraviolet rays. Next, the surface condition of the adhesive body when it was peeled off after irradiation with ultraviolet rays was as shown in Table 1.
4, there is no contamination.

Although there was no contamination in Comparative Examples 1 and 2, in this case, the base layer and the temporary adhesive layer were likely to separate. Such interlayer strength between the base material layer and the temporary adhesive layer becomes important when the adhesive force of the temporary adhesive layer is large. On the other hand, in the case of Examples, the above-mentioned separation was not observed. There is no problem at all under normal usage conditions, but to put it bluntly, the interlayer strength of Examples 1 and 4, which include an intermediate layer in the temporary adhesive layer, is higher than that of Examples 2 and 3, which do not include this. A trend was observed.
Table 1.9 Piha〈chick strength (attached body: aluminum plate, unit: g
/25 items) Note 1) Ultraviolet rays meter - Operating temperature 63℃ Water spray 18 minutes / 120 minutes Irradiation time 48 hours 2) At room temperature (20℃) 900 ObservationThe reason why the increase in adhesive force of the surface protection film according to the present invention is suppressed is that the generation and growth of radicals in the modified polyolefin molecular chain is suppressed by the ultraviolet absorber and antioxidant, resulting in a decrease in molecular weight. At the same time, there is no chemical change such as elimination of acetic acid groups, which reduces the increase in adhesive strength. It is thought that this is because it acts as a surfactant, and for this reason, a layer with weak cohesive force is formed locally or entirely between the temporary adhesion layer and the adherend.

As described above, according to the present invention, a surface protective film can be obtained which can be easily peeled off from the surface of the adherend even when exposed outdoors and does not leave so-called adhesive residue on the surface of the adherend. The range of use of film can be expanded, and the effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a manufacturing apparatus for a surface protection film of the present invention. Explanation of symbols, 1...Screw, 2...Cylinder, 3...Pipe hole, 4...Spider, 5...Mixing head, 6...Hollow body, 7...Adapter, 8...Flock, 9...Nose , 10... Conical part, 11... Spider part, 1
2... Die lip, 13... Air inlet, 14...
・Hopper, 15... Pipe entrance, 16... Weir, 17
...Connection part, 18...Hopper, 19...250 extruder, 20...150 extruder. Figure 1

Claims (1)

[Scope of Claims] 1. A surface protection film comprising a film base layer made of a thermoplastic resin and a temporary adhesion layer mainly composed of modified polyolefin, wherein at least the temporary adhesion layer comprises (a) distearyl 3, A surface protective film comprising 3'-thiodipropionate or dilauryl 3,3'-thiodipropionate, and (b) an ultraviolet absorber. 2. The surface protection film according to claim 1, wherein the modified polyolefin is a 10 to 70% by weight vinyl acetate copolymer.