JPH09100453A - Protective tacky film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a protective tacky film having a suitable sticking property and re-peelable property at an ambient temperature, good in pasting performance to a pasted body such as a signboard, and capable of sufficiently withstanding against an exposure to outside, etc. for a long period of time. SOLUTION: This protective tacky film is obtained by providing a heat sensitive acrylic tackiness agent layer obtained by blending 100 pts.wt. copolymer consisting of a (meth)acrylic acid alkyl ester, (meth)acrylic acid and acrylonitrile with 2-50 pts.wt. vinyl acetate-vinyllactam copolymer on the one of surfaces of a transparent synthetic resin film base material containing an ultraviolet absorbing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a protective pressure-sensitive adhesive film, and more particularly to a protective pressure-sensitive adhesive film for outdoor signboards and the like.

[0002]

2. Description of the Related Art When using characters or pictures photographed or copied on photographic film or photographic paper as a signboard,
Since these consist of silver salt emulsions, especially when used outdoors, they are susceptible to discoloration under the influence of sunlight, especially ultraviolet rays.
Also, when using printed materials such as posters as signboards,
Since it uses printing ink, it does not change color a little, but it also changes color after a long period of time. Furthermore, due to the effects of rainwater, dust, etc., or intentional vandalism outdoors,
Signboards such as photographic film, photographic paper and posters will be damaged.
When it is used indoors, it is not affected as much as outdoors, but it may also be discolored and damaged.

In order to protect the signboard from these discoloration and damage, a protective pressure-sensitive adhesive film in which a pressure-sensitive adhesive layer is laminated on a base film has been devised. In particular, in order to prevent discoloration due to sunlight or ultraviolet rays, ultraviolet rays are used. A protective pressure-sensitive adhesive film using a base material film containing an absorber has been devised and used (made by UK Ademco, Telc, both using a vinyl chloride resin film base material containing an ultraviolet absorber. Exist).

When a protective pressure-sensitive adhesive film is attached to a signboard such as characters or pictures photographed or copied on photographic film or photographic paper, a lamination method using a heat roll or a vacuum pressing method is usually used. Even if there is any, it comprises a step of temporarily adhering the display material of the signboard such as the photographic film or photographic paper and the protective pressure-sensitive adhesive film, and a step of firmly adhering the both so as to withstand long-term exposure.

In the above-mentioned temporary sticking step, air is not trapped between the signboard such as letters and pictures using photographic film or photographic paper and the protective pressure-sensitive adhesive film without wrinkling or foreign matter such as dust is not caught. It is desirable that it can be attached. If it is only the above requirements, it may be a protective adhesive film that is not sticky at room temperature and has a strong rigidity, but in the case of such a protective adhesive film, the work of the process of firmly adhering the two next Efficiency does not increase.

As a pressure-sensitive adhesive used for the above-mentioned protective adhesive film having removability, for example, Japanese Patent Publication No.
JP-A-3-28114 discloses an acrylic acid ester-based polymer containing an acrylic acid alkyl ester such as butyl acrylate and 2-ethylhexyl acrylate as a main component.
Disclosed is a pressure-sensitive adhesive composition which is improved in adhesive strength by adding a homopolymer of vinyl lactam such as vinyl-2-pyrrolidone and imparts water vapor permeability and hot melt coatability. .

However, in the above pressure-sensitive adhesive composition, the acrylic ester polymer and the vinyl lactam homopolymer have poor compatibility with each other, so that they are easily separated from each other, and the adhesive strength, heat resistance and other properties are improved. Can not be fully exerted.

From the above-mentioned circumstances, the adhesiveness at room temperature is protected, the removability such that even if there is a problem in the temporary sticking process can be immediately corrected, and the heat-resistant adhesive strength that can withstand outdoor postings is protected. There is a demand for adhesive films for automobiles.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and an object of the present invention is to provide appropriate tackiness and removability at room temperature and removability after thermocompression bonding. An object of the present invention is to provide a protective pressure-sensitive adhesive film that has good properties, has good adhesion performance to adherends such as signboards, and can sufficiently withstand long-term exposure to the outdoors.

[0010]

DISCLOSURE OF THE INVENTION The present invention provides a copolymer composed of an alkyl (meth) acrylate, (meth) acrylic acid and acrylonitrile on one side of a transparent synthetic resin film substrate containing an ultraviolet absorber. A protective pressure-sensitive adhesive film is characterized by comprising a heat-sensitive acrylic pressure-sensitive adhesive layer in which 2 to 50 parts by weight of vinyl acetate-vinyl lactam copolymer is mixed with 100 parts by weight. is there.

The transparent synthetic resin film used in the protective pressure-sensitive adhesive film of the present invention is not particularly limited as long as it has excellent transparency. For example, polyethylene terephthalate film, polyethylene film, plasticized Examples thereof include vinyl chloride resin film and polycarbonate film. The thickness of the synthetic resin film is not particularly limited, but is generally 10 to 100 μm.
Some are used.

Examples of the ultraviolet absorber added to the transparent synthetic resin film include benzotriazole derivatives such as 2- (2'-hydroxy-5'-methyl) -2H-benzotriazole and 2,4-dihydroxy. Benzophenone derivatives such as benzophenone, salicylic acid derivatives such as phenyl salicylate, 2-ethylhexyl-2-
Examples thereof include cyanoacrylate derivatives such as cyano-3,3′-diphenylacrylate. The addition amount of the ultraviolet absorber depends on the application of the product, but is generally about 1 to 5% by weight based on the synthetic resin.

The heat-sensitive acrylic pressure-sensitive adhesive layer used in the protective pressure-sensitive adhesive film of the present invention is vinyl acetate based on 100 parts by weight of a copolymer composed of (meth) acrylic acid alkyl ester, (meth) acrylic acid and acrylonitrile. It is obtained from a resin composition containing 2 to 50 parts by weight of a vinyl lactam copolymer.

The copolymer of (meth) acrylic acid alkyl ester, (meth) acrylic acid and acrylonitrile has a relatively low glass transition temperature of butyl acrylate, 2-ethylhexyl acrylate or the like (-50 ° C. or lower). Aggregation containing (meth) acrylic acid alkyl ester capable of forming a tacky polymer as a main component and forming a polymer having a relatively high glass transition temperature (50 ° C. or higher) such as (meth) acrylic acid or acrylonitrile. It is a copolymer that has both initial tackiness and temporal adhesive strength obtained by copolymerizing force components.

Examples of the vinyl lactam copolymerizable with the above vinyl acetate include 1-vinyl-2-pyrrolidone, 1-vinyl-5-methyl-2-pyrrolidone, 1-vinyl-2-piperidone and N-vinyl. -[Epsilon] -caprolactam is mentioned, and 1-vinyl-2-pyrrolidone is particularly preferably used.

The vinyl lactam content in the above vinyl acetate-vinyl lactam copolymer is preferably 20 to 80 mol%, and the glass transition temperature of the resulting copolymer is 50.
~ 90 ° C is preferred. The amount of the vinyl acetate-vinyl lactam copolymer to be blended is 2 with respect to 100 parts by weight of the copolymer consisting of (meth) acrylic acid and acrylonitrile.
-50 parts by weight, preferably 3-30 parts by weight. If the blending amount is less than 2 parts by weight, the glass transition temperature of the resulting heat-sensitive acrylic pressure-sensitive adhesive increases, tack on the adherend is lost, and the performance of the protective pressure-sensitive adhesive film deteriorates.
On the other hand, if the blending amount exceeds 50 parts by weight, the glass transition temperature of the resulting heat-sensitive acrylic pressure-sensitive adhesive decreases, the tack on the adherend increases, and the removability decreases.

The heat-sensitive acrylic pressure-sensitive adhesive thus obtained is provided as a pressure-sensitive adhesive layer on one surface of a transparent synthetic resin film substrate containing the above-mentioned ultraviolet absorber, but the means is not particularly limited. A coating method may be employed in which the above copolymer composition is made into a solution of toluene, xylene, ethyl acetate or the like, and is coated and dried using a coating machine such as a knife coater, comma coater or roll coater. Further, at the time of coating, the pressure-sensitive adhesive layer may be directly applied on the substrate, but a method of transferring the pressure-sensitive adhesive layer provided on the process paper having releasability to the substrate is adopted. You may be asked.
In addition, it is preferable that the surface of the base material is subjected to corona discharge treatment in advance or a conventionally used undercoating agent is applied in advance in order to enhance the adhesiveness with the pressure-sensitive adhesive layer.
The thickness of the pressure-sensitive adhesive layer is appropriately set depending on the intended use of the product and the properties of the adherend, but is generally 10 to 50 μm.
It is provided to the extent.

The adhesive layer provided on one surface of the transparent synthetic resin film base material containing the ultraviolet absorber as described above may be stored by laminating release paper, but the adhesive layer of the base material is provided. The surface that is not covered (back surface) is released,
It may be rolled up and stored.

The protective pressure-sensitive adhesive film of the present invention comprises a transparent synthetic resin film substrate containing an ultraviolet absorber on one side,
Vinyl acetate-vinyl lactam copolymer 2 to 50 based on 100 parts by weight of a copolymer consisting of (meth) acrylic acid alkyl ester, (meth) acrylic acid and acrylonitrile.
Since a heat-sensitive acrylic pressure-sensitive adhesive layer containing parts by weight is provided, it retains sufficient initial adhesive force to the adherend and has removability. Degassing between the adherend and the adherend is easy at the time of sticking, and it has excellent performance in temporary sticking workability, and also has excellent heat sensitivity. It is possible to obtain a strong bond that can withstand the exposure of.

[0020]

Next, embodiments of the present invention will be described.

(Example 1) [Preparation of acrylic pressure-sensitive adhesive] butyl acrylate-methacrylic acid-acrylonitrile copolymer butyl acrylate 85 mol%, methacrylic acid 3 mol%,
Acrylonitrile was copolymerized at a ratio of 12 mol% to prepare an ethyl acetate solution of a butyl acrylate-methacrylic acid-acrylonitrile copolymer having a solid content of 20% by weight.

Vinyl acetate-1-vinyl-2-pyrrolidone copolymer 70 mol% vinyl acetate, 1-vinyl-2-pyrrolidone 3
Copolymerization was carried out at a ratio of 0 mol% to prepare a vinyl acetate-1-vinyl-2-pyrrolidone copolymer ethyl alcohol solution having a solid content of 50% by weight.

The above-mentioned butyl acrylate-methacrylic acid-acrylonitrile copolymer ethyl acetate solution and vinyl acetate-1-vinyl-2-pyrrolidone copolymer ethyl alcohol solution were uniformly mixed at a solid content ratio of 100: 3 (weight ratio). An acrylic pressure-sensitive adhesive was prepared by mixing.

One side of a polyethylene terephthalate film having a thickness of 50 μm is subjected to corona discharge treatment, the above-mentioned acrylic adhesive is applied to the treated surface and dried to form an adhesive layer having a thickness of 20 μm to prepare a protective adhesive film. did.

(Examples 2 to 3) An ethyl acetate solution of the butyl acrylate-methacrylic acid-acrylonitrile copolymer of the acrylic adhesive used in Example 1 and a vinyl acetate-1-vinyl-2-pyrrolidone copolymer. A protective pressure-sensitive adhesive film was produced in the same manner as in Example 1 except that the mixing ratio of the ethyl alcohol solution was changed to the ratios shown in Table 1.

(Comparative Examples 1-2) Ethyl acetate solution of butyl acrylate-methacrylic acid-acrylonitrile copolymer of acrylic pressure-sensitive adhesive used in Example 1 and vinyl acetate-1-vinyl-2-pyrrolidone copolymer A protective pressure-sensitive adhesive film was produced in the same manner as in Example 1 except that the mixing ratio of the ethyl alcohol solution was changed to the ratios shown in Table 1.

Performance Evaluation The protective pressure-sensitive adhesive films obtained in the above Examples and Comparative Examples were deaired at the time of temporary attachment, removability at the time of temporary attachment,
The adhesive strength after thermocompression bonding and the removability after thermocompression bonding were observed and measured by the methods described below to evaluate their performance. The evaluation results are shown in Table 1.

Air-Removing Property During Temporary Adhesion The obtained protective pressure-sensitive adhesive film was placed on a color printing paper of A-4 plate and temporarily adhered by a pressure roller of 2 kg according to a commonly used method. The state of de-airing when pasting,
◯: Deaeration is possible and bubbles cannot be seen on the temporary attachment surface, ×: Air bubbles cannot be deaerated and the temporary attachment surface has air bubbles or other temporary attachment defects, and there are two stages. evaluated.

Removability at Temporary Adhesion The protective adhesive film temporarily adhered on the color printing paper of A-4 plate, which was temporarily adhered in the test of the preceding paragraph, is manually re-applied by a manual operation which is usually performed at the time of actual correction work. The releasability was evaluated in two levels: ◯: the protective adhesive film can be repeatedly peeled off without damaging the color photographic paper surface as an adherend, and x: the color photographic paper surface cannot be peeled without damaging the color photographic paper surface. .

The sample temporarily adhered by the adhesive strength after thermocompression bonding was thermocompression bonded to a thermocompression-bonding roller heated at 80 ° C. at a speed of 30 mm / min and a compression force of 5 kg / cm ² to protect the color photographic paper and protection. The adhesive film was adhered. After the thermocompression-bonded sample was left at room temperature for 24 hours, a 180 ° peel test was performed under the condition of 23 ° C. × 65% RH to measure the adhesive strength.

Removability after thermocompression bonding While applying hot air of 80 ° C. to the sample thermocompression bonded in the previous section, the removability was evaluated in the same manner as in the removability test at the time of temporary attachment, ◯: on the adherend Evaluation was made in two stages: one in which the protective pressure-sensitive adhesive film could be repeatedly peeled off without damaging the certain color photographic paper surface, and x: one in which the color photographic paper surface could not be peeled off without damage.

[0032]

[Table 1]

[0033]

Since the protective pressure-sensitive adhesive film of the present invention is constructed as described above, it has a sufficient initial adhesive force to the adherend and, at the same time, it is adhered to the adherend during temporary attachment. Is easy to degas, has removability, exhibits excellent workability for temporary attachment, and is also excellent in heat sensitivity. It can be used as a pressure-sensitive adhesive film for protection of signboards, etc. with a strong adhesive strength that can withstand.

Claims (1)

[Claims] 1. A transparent synthetic resin film substrate containing an ultraviolet absorber, on one side of which vinyl acetate-based on 100 parts by weight of a copolymer composed of (meth) acrylic acid alkyl ester, (meth) acrylic acid and acrylonitrile. A protective pressure-sensitive adhesive film, comprising a heat-sensitive acrylic pressure-sensitive adhesive layer containing 2 to 50 parts by weight of a vinyl lactam copolymer.