JPS6016998B2 - Masking film with improved weather resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temporary adhesion film (masking film) for surface protection that significantly suppresses increase in adhesive strength over time due to deterioration in weather resistance.

Generally, masking films are temporarily attached to stainless steel plates, colored steel plates, aluminum plates, PVC plates, polyester plates, etc.
These serve as surface protection until they are put into practical use.

Currently, masking films in which a polyvinyl chloride or polyolefin film is used as a base material and a tackifier used in general adhesive tapes is attached thereto (so-called adhesive film) are often used.

However, after these materials are masked, their adhesive strength increases over time due to exposure to ultraviolet rays or heat irradiation, and when the masking film is peeled off in practical use, a portion of the adhesive remains on the adherend. For this reason, even if it serves as a surface protection film as a masking film, it significantly reduces the commercial value of the adhesive itself. In view of this, a so-called glueless film, that is, a polyvinyl chloride or polyolefin film is used as the base material, and an ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA), which is adhesive at room temperature, is used as a temporary adhesive layer. ) Film laminated 2
Layered films are commonly considered.

However, EVA has a low melting point of less than 6000, and even if it temporarily adheres to the adherend at the time of masking and serves its purpose, the adhesive strength with the adherend weakens when exposed to ultraviolet rays or heat after masking. It increases significantly over time and becomes difficult to peel off.

In view of these points, the inventors of the present invention have conducted extensive research into creating a masking film that suppresses changes in adhesive strength over time, can be peeled off smoothly in practical use, and does not leave any residue on the adherend. He came up with an invention.

That is, in the present invention, a polyvinyl chloride or polyolefin film is used as the base film, and an ethylene-vinyl acetate copolymer film having a pinyl acetate content of 15 to 40% by weight is laminated thereon as a temporary adhesive layer. In the masking film made into a layered film, the temporary adhesion layer contains 0.01-0.1% by weight of peroxide and 0.1-1.0% of ultraviolet absorber.
Weight % and lubricant 0.1-1. The masking film is made by adding % by weight of each.

The vinyl acetate content of EVA must be selected depending on the material of the adherend, but in any case, in order to have effective adhesiveness, it needs to be 15% by weight or more, and from the viewpoint of moldability, Optimally, the weight percentage is less than or equal to .

Further, the effects of individual additives or combinations of additives on the increase in adhesive strength over time will be detailed below.

Generally, when EVA is crosslinked, its heat resistance temperature (temperature at which it shrinks) increases from 40 to 60 points to over 10,000 points.

However, after crosslinking, it is essential to add an ultraviolet absorber to keep the crosslinked structure stable even when exposed to ultraviolet rays or heat, and to prevent changes in adhesive strength over time.
Additionally, it is necessary to add peroxide for crosslinking. Furthermore, it is essential to add a lubricant in order to suppress an increase in adhesive strength so that the film can be used practically as a masking film.

The amount of the ultraviolet absorber to be added is 0.1 to 1. Weir weight % is appropriate, and the amount of peroxide added is effectively 0.01 to 0.1 weight % in view of the crosslinking effect and the reduction in film formability due to excessive crosslinking.

Also, the amount of lubricant added is 0.1 to 1. An appropriate weight % of 1. If the weight percentage exceeds , the embossing effect will be rapid and the adhesive strength during masking will be significantly reduced, which is undesirable.

Moreover, the effect of suppressing the increase in adhesive strength is significantly exhibited by the synergistic effect of crosslinking and ultraviolet absorption, and the effect is hardly found with either one of them.

The peroxide used may be any of hydroperoxide type, dialkyl peroxide type, diacyl peroxide type, peroxyester type, and ketone peroxide type, but peroxyester type The crosslinking effect is large when the amount added is appropriate for the system. The ultraviolet absorber may be of the commonly used penzophenone type, benzotriazole type, or phenyl salicylate type, but among them, the penzotriazole type is effective. Solvents include paraffin, fatty acid, fatty acid amide, ester, alcohol, and metal soaps, among which fatty acid amide solvents, such as erucamide, oleylamide, and methylene bisstearamide, are the most popular solvents. Methylene bisstearamide is particularly effective. With the above-mentioned formulation that prevents aging, it completely temporarily adheres to the adherend during masking, and even after long-term exposure to ultraviolet rays and heat, the adhesive strength hardly increases and the adhesive remains smooth without leaving any adhesive residue. This made it possible to peel it off.

Hereinafter, the effect of preventing changes over time according to the present invention will be specifically shown in Examples, but the present invention is not limited thereto in any way.

Example '1} Base material is polyvinyl chloride film (thickness: 60 mm)
EVA film (vinyl acetate content 33%) as temporary adhesion layer
) (film thickness 15 mm) was used as a base, and the additives shown in the table were added.

'21 Buffed stainless steel plate (2
5 sides x 12 enemies) was used.

'31 Adhesive strength was measured using a Tensilon type constant speed tensile tester, with 180o peeling and a tensile rate of 30 ratio/min.
I did it.

'41 Weather resistance was evaluated using a sunshine type weather meter on samples that had been treated for 100 and 20 hours under conditions of 60 o'clock o'clock and rain time of 12 minutes/60 minutes.

Effect of preventing changes in height due to the present invention *1. Tertiary butyl peroxybenzoate (manufactured by Sumitomo 3M) *2. Substituted hydroquine phenyl besozotriazole (manufactured by Bayer AG) *3. Coumetine pistalamide (manufactured by Nippon Kasei Co., Ltd.) *4. Delamination occurs between the base material and the temporary adhesive layer, and the entire temporary adhesive layer remains on the adhesive body.

Claims (1)

[Claims] 1 A two-layer film was made by using a polyvinyl chloride or polyolefin film as a base material, and laminating an ethylene vinyl acetate copolymer film with a vinyl acetate content of 15 to 40% by weight as a temporary adhesive layer to this. In the masking film, peroxide is added to the temporary layer from 0.01 to
A masking film containing 0.1% by weight, 0.1 to 1% by weight of an ultraviolet absorber, and 0.1 to 1% by weight of a lubricant.