JP2000136358A - Laminated film having ultraviolet-absorbing function and pressure-sensitive adhesive sheet for surface protection prepared by using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film which is excellent in weatherability and is almost free of blocking by forming a layer having an ultraviolet-absorbing function in a substrate. SOLUTION: A layer having an ultraviolet-absorbing function is formed, preferably by printing, in a substrate comprising at least one film made preferably of a polyolefin or polyvinyl chloride; that is, this laminated film has a structure wherein a layer having an ultraviolet-absorbing function is sandwiched between substrate materials. A pressure-sensitive adhesive layer is formed on one side of the laminated film, thus giving a surface-protecting pressure-sensitive adhesive sheet, which has a weatherability not degraded by the adhesive and which, when wound into a roll and then unwound, does not cause the ultraviolet- absorbing layer to be removed by the adhesive layer. It is preferable that the laminated film is subjected to a corona treatment when the adhesive layer is formed thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film having an ultraviolet absorbing function and a pressure-sensitive adhesive sheet for surface protection using the laminated film as a support.

[0002]

2. Description of the Related Art As a measure for protecting a plastic film and a pressure-sensitive adhesive of a pressure-sensitive adhesive sheet for surface protection from irradiation of ultraviolet rays such as sunlight, light stabilizers and ultraviolet absorbers have been conventionally used. It is in plastic film and adhesive.

[0003] With the diversification of methods of using the pressure-sensitive adhesive sheet for surface protection, there has been an increasing demand for products that can be used outdoors or the like. On the other hand, he was too weak to respond to this request.

Therefore, the present inventors have conceived of providing a printing layer by printing an ultraviolet absorber on a plastic film during the completion of the present invention. However, the following method is used to form a printing layer by a conventional method. There was a problem.

When a printing layer is provided on a plastic film, it is common to provide a printing layer on the outer surface of the plastic film. When a printing layer is provided on a support substrate of a film made of polyolefin such as polyethylene, polypropylene, or a blend polymer of polyethylene and polypropylene, a corona-treated surface is provided on the film, and the printing layer is provided thereon. This method has ensured a sufficient anchoring force between the printing layer and the supporting substrate. Also,
When an acrylic or natural rubber-based pressure-sensitive adhesive layer is provided on these support substrates, it is common to provide a corona-treated surface on the support substrate and provide an adhesive layer thereon. If you do not provide an adhesive layer on top of processing such as
Sufficient anchoring power cannot be obtained, and it does not function sufficiently as an adhesive sheet for surface protection.

In view of the above, a method for providing an acrylic or natural rubber-based pressure-sensitive adhesive layer on a polyolefin film having a printed layer is based on a film provided with a printed layer. And the method of providing a pressure-sensitive adhesive layer on the side of the corona-treated surface, and the method of providing a corona-treated surface on the surface opposite to the corona-treated surface of the film on which the printed layer is provided.

However, when the pressure-sensitive adhesive sheet for surface protection is produced by these methods, there are the following problems. When a pressure-sensitive adhesive layer is provided on the corona-treated surface on the printing layer side, delamination occurs between the printing layer and the supporting substrate after weather resistance deterioration, maintaining the weather resistance of the conventional surface protection pressure-sensitive adhesive sheet Can not. In addition, when the corona treatment is performed on the surface on the opposite side of the printing layer and the pressure-sensitive adhesive layer is provided, there is no problem with respect to weather resistance deterioration. The surfaces are apt to cause a blocking phenomenon, and the productivity is greatly impaired.

On the other hand, when a printing layer is provided on a polyvinyl chloride film as a supporting substrate, it is general to provide a printing layer without performing a corona treatment on the supporting substrate. But,
When the pressure-sensitive adhesive sheet for surface protection is formed into a roll, if the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer is large, the print layer is taken up by the pressure-sensitive adhesive layer when the roll is formed. Occurs.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and it is an object of the present invention to provide a film which absorbs ultraviolet rays such as outdoors and has excellent weather resistance. Another object of the present invention is to provide a film in which a blocking phenomenon does not easily occur when a roll-shaped product is formed. A further object of the present invention is to maintain the weather resistance of a pressure-sensitive adhesive sheet for surface protection comprising a pressure-sensitive adhesive layer provided on one side of a film as a support. Also,
When the pressure-sensitive adhesive sheet for surface protection is formed into a roll-formed product, a surface-protective pressure-sensitive adhesive sheet is provided in which the layer having an ultraviolet absorbing function is not likely to be taken up by the pressure-sensitive adhesive layer when the roll-formed product is unwound. The purpose is to:

The present inventors have noticed that these problems are unavoidable when the printing layer is present on the outermost surface of the support, and in order to solve the problem, the printing layer must be formed. The focus was on the need to move from the outermost layer to the inner layer.

As a result of further intensive studies, the inventors of the present invention have found that a laminated film having a structure in which a layer having an ultraviolet absorbing function is sandwiched by a supporting substrate, and that the laminated film is used as a support, and one side of the laminated film It has been found that the above problem can be solved by providing a pressure-sensitive adhesive sheet for surface protection provided with a pressure-sensitive adhesive layer.

[0012]

That is, the laminated film of the present invention is characterized in that a layer having an ultraviolet absorbing function (hereinafter also referred to as "ultraviolet absorbing layer") is formed in a supporting substrate. . In a preferred embodiment of the laminated film of the present invention, the ultraviolet absorbing layer is formed by printing. Also,
In another preferred embodiment, the supporting substrate is made of one or more films made of polyolefin or polyvinyl chloride.

The pressure-sensitive adhesive sheet for surface protection of the present invention is characterized in that the laminated film of the present invention is used as a support, and a pressure-sensitive adhesive layer is provided on one side of the laminated film.

[0014]

According to the laminated film of the present invention, since the ultraviolet absorbing layer is present in the inner layer of the supporting substrate, the blocking phenomenon hardly occurs. By providing the laminated film of the present invention as a support and providing an adhesive layer on one side of the laminated film, the weather resistance of the conventional adhesive is not impaired. Further, when the surface-protecting pressure-sensitive adhesive sheet is formed into a roll-shaped product, it is possible to obtain a surface-protecting pressure-sensitive adhesive sheet that is not likely to be taken off by the pressure-sensitive adhesive layer when the roll-shaped product is rewound. it can.

At present, there are various pressure-sensitive adhesive sheets for surface protection using a film having a printing layer as an outer layer, but there is provided a pressure-sensitive adhesive sheet for surface protection using a film containing a printing layer having an ultraviolet absorbing function in an inner layer. This is the first attempt. Conventionally, the effect of using a laminated film having a printed layer, which is considered useless from the viewpoint of film production cost, provided as an inner layer of a supporting substrate as a support for a pressure-sensitive adhesive sheet for surface protection is greater than expected.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The laminated film of the present invention has a laminated structure in which an ultraviolet absorbing layer is sandwiched between the same or different kinds of supporting base materials.

The ultraviolet absorbing layer is adjusted so that printing can be performed by blending a benzophenone-based, triazole-based, or hindered amine-based ultraviolet absorber alone or with a binder component or a solvent component such as a synthetic resin. It is formed by printing on the surface of the supporting substrate by a known printing means such as a gravure printing method or a flexographic printing method.

The UV absorber is not particularly limited as long as it is a material having a UV absorbing function. From the viewpoint of ease of printing and weather resistance, a polymer UV such as a benzophenone acrylic resin emulsion is used. Absorbents are preferred.

The ultraviolet absorbing layer may further contain a pigment. As the pigment, an inorganic pigment such as titanium oxide and an organic pigment such as phthalocyanine can be used.

The ultraviolet absorbing layer only needs to have a thickness capable of maintaining ultraviolet shielding properties and other physical properties.
It is preferably from 5 to 50 μm, particularly preferably from 0.5 to 5 μm.

The ultraviolet absorbing layer is usually sandwiched between the same or different types of supporting substrates. As such a support substrate, one or more films of polyolefin (polyethylene, polypropylene, polyethylene-polypropylene blend and the like), polyvinyl chloride and the like are used, but the present invention is not limited thereto. The thickness of the supporting base material is 10 to 500 μm, preferably 20 to 150 μm in a state where the layer having the ultraviolet absorbing function is sandwiched and formed into a film.
Is common, but is not limited to this.

The laminated film of the present invention can be formed by lamination. Laminate is mainly 70
Performed by heat lamination at ~ 150 ° C. The most appropriate condition may be selected depending on the material and thickness of the film used for the supporting substrate.

The pressure-sensitive adhesive sheet for surface protection of the present invention comprises the laminated film of the present invention as a support and an adhesive layer provided on one side of the film.

The pressure-sensitive adhesive layer provided on the support is made of acrylic,
A pressure-sensitive adhesive layer containing a cross-linking pressure-sensitive adhesive such as a natural rubber-based pressure-sensitive adhesive is preferred, but not limited thereto. The thickness of the pressure-sensitive adhesive layer is 0.1 to 100 μm, preferably 1 to 30 μm.
m is preferred, but not limited thereto.

The pressure-sensitive adhesive is not particularly limited, and includes those known per se. For example, acrylic, rubber,
Any of silicone-based adhesives and the like can be used.

In the case of providing a pressure-sensitive adhesive layer on a laminated film, particularly when the supporting substrate is a film composed of polyolefin such as polyethylene, polypropylene, polyethylene-polypropylene blend polymer, etc. It is desirable to apply a treatment. The corona treatment is performed at a treatment intensity of 38 mN / m or more, especially 40 to 60 mN / m.

[0027]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, Comparative Examples, and Experimental Examples, but the present invention is not limited thereto.

Example 1 Density 0.923 (see JIS K-6760), melt flow index (MI) 2 g / 10 min (JIS
K-6760) polyethylene (PE) resin in an inflation extrusion film forming machine to form a film having a thickness of 3
A 0 μm PE film was obtained. On one side of this PE film, a printing layer composed of a benzophenone-based acrylic resin emulsion (polymeric UV absorber) having a thickness of 2 μm is formed, and a PE film similar to the above is laminated on the surface of the printing layer to form a laminated film. I got One side of the laminated film was subjected to corona treatment so as to have a treatment strength of 42 mN / m, to obtain a wound PE laminated film having an ultraviolet absorbing layer (printing layer) as an inner layer.

Example 2 A wound PE laminated film was obtained in the same manner as in Example 1 except that the benzophenone-based acrylic resin emulsion was replaced with a triazole-based acrylic resin emulsion.

Example 3 60 parts by weight of ethyl acrylate (EA), 40 parts by weight of 2-ethylhexyl acrylate (2EHA), and 5 parts of hydroxyethyl acrylate (HEA) were provided on the corona-treated side of the PE laminated film prepared in Example 1. To 100 parts by weight of an acrylic polymer consisting of parts by weight, an adhesive layer 10 μm consisting of toluylene diisocyanate (TDI) and 1 part by weight of a hindered amine light stabilizer was applied and dried.
A roll-shaped pressure-sensitive adhesive sheet for surface protection shown in FIG. 1 was obtained.

Example 4 In Example 3, the procedure of Example 3 was repeated, except that the PE laminated film prepared in Example 2 was used instead of the PE laminated film prepared in Example 1. The wound adhesive sheet for surface protection shown in the figure was obtained.

Comparative Example 1 Density 0.923, Melt Flow Index (MI) 2
g / 10min polyethylene (PE) resin is formed into a film by an inflation extrusion film forming machine, and the thickness is 60 μm.
Was obtained. Thereafter, a corona treatment was applied to one side of the PE film so that the treatment strength became 42 mN / m, and an ultraviolet absorbing layer (printing layer) of a benzophenone-based acrylic resin emulsion having a thickness of 2 μm was provided on the corona treated side. A wound PE laminated film was obtained.

Comparative Example 2 Density 0.923, Melt Flow Index (MI) 2
g / 10min polyethylene (PE) resin is formed into a film by an inflation extrusion film forming machine, and the thickness is 60 μm.
Was obtained. Thereafter, a corona treatment is applied to both sides of the PE film so that the treatment strength becomes 42 mN / m, and a UV-absorbing layer (printing layer) of a benzophenone-based acrylic resin emulsion having a thickness of 2 μm is provided on one side to form a winding. Was obtained.

Comparative Example 3 The 10 μm pressure-sensitive adhesive layer used in Example 3 was applied on the ultraviolet absorbing layer (printing layer) side of the PE laminated film described in Comparative Example 1 and dried. A pressure-sensitive adhesive sheet for surface protection was obtained.

Comparative Example 4 On the side of the PE printing film described in Comparative Example 2 opposite to the ultraviolet absorbing layer (printing layer), the adhesive layer 10 μm used in Example 1 was applied and dried. Further, a release agent composed of polyvinyl butyral N-octadecyl carbamate was applied on the ultraviolet absorbing layer (printing layer) side by 30 nm and dried.
A roll-shaped pressure-sensitive adhesive sheet for surface protection shown in FIG. 3 was obtained.

Comparative Example 5 A pressure-sensitive adhesive sheet for surface protection was obtained in the same manner as in Comparative Example 1, except that no ultraviolet absorbing layer (printing layer) was provided. That is, density 0.923, melt flow index (M
I) Polyethylene (PE) resin of 2 g / 10 min was formed into a film by an inflation extrusion film forming machine, and a thickness of 6
A 0 μm PE film was obtained. Thereafter, one side of the PE film was subjected to corona treatment so that the treatment strength was 42 mN / m. Acrylic polymer 10 consisting of 60 parts by weight of ethyl acrylate (EA), 40 parts by weight of 2-ethylhexyl acrylate (2EHA), and 5 parts by weight of hydroxyethyl acrylate (HEA) on the corona-treated side
0 parts by weight of toluylene diisocyanate (TD
I), a 10 μm pressure-sensitive adhesive layer comprising 1 part by weight of a hindered amine-based light stabilizer was applied and dried to obtain a current wound surface protection pressure-sensitive adhesive sheet.

Experimental Example 1 (About Prevention of Blocking of Film) The roll-shaped products obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were dried in a dryer at 40 ° C. for 1 week (1 W) and for 1 month (1 W
M) Roll preservation was performed to check for the occurrence of a blocking phenomenon (a phenomenon in which film surfaces adhere to each other). The results are shown in Table 1.

[0038]

[Table 1]

EXPERIMENTAL EXAMPLE 2 The pressure-sensitive adhesive sheets for surface protection prepared in Examples 3 and 4 and Comparative Examples 3, 4 and 5 were stuck on a SUS430BA plate.
S. W. M. (Sunshine weather meter), and the peeling of the printed layer and the adhesive residue were confirmed. The results are shown in Table 2.

[0040]

[Table 2]

Summary of Experimental Results From the results in Table 1 above, when the corona treatment was performed on only one side of the PE laminated film (Example 1, Comparative Example 1),
It was found that the blocking phenomenon was less likely to occur as compared with the case where the corona treatment was performed on both surfaces (Comparative Example 2). In addition, from the results in Table 2, by providing the pressure-sensitive adhesive layer on the surface on which the ultraviolet absorbing layer (printing layer) is not applied in the pressure-sensitive adhesive sheet for surface protection (Examples 3, 4 and Comparative Example 4), the pressure-sensitive adhesive was It has been found that a surface protection film which does not deteriorate the weather resistance which is conventionally provided can be produced. In Comparative Example 1, the blocking phenomenon hardly occurred, but the pressure-sensitive adhesive sheet for surface protection using Comparative Example 1 (Comparative Example 3) was inferior in weather resistance. The pressure-sensitive adhesive sheet for surface protection using Comparative Example 2 (Comparative Example 4) had better weather resistance than those of the other Comparative Examples, but Comparative Example 2 was more likely to cause a blocking phenomenon.

From the comparison between Example 3 and Example 4, even when the constitution of the pressure-sensitive adhesive sheet for protecting the surface is the same, the weather resistance of the polymer type printed layer of the UV absorber is higher than that of the low molecular weight type. Turned out to be. Further, it was found that all of the types having the ultraviolet absorbing layer printed thereon had better weather resistance than Comparative Example 5 of the current type having no ultraviolet absorbing layer.

In view of the results in Tables 1 and 2, by having a printing layer of an ultraviolet absorber in the inner layer of the support,
It was found that a laminated film in which the blocking phenomenon hardly occurred was obtained. In addition, a pressure-sensitive adhesive sheet for surface protection that exceeded the weather resistance of the conventional pressure-sensitive adhesive by several hundred hours could be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pressure-sensitive adhesive sheet for surface protection shown in Examples 3 and 4.

FIG. 2 is a sectional view of a pressure-sensitive adhesive sheet for surface protection shown in Comparative Example 3.

FIG. 3 is a sectional view of a pressure-sensitive adhesive sheet for surface protection shown in Comparative Example 4.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Isamu Miyoshi 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 4F100 AK03B AK04 AK15B AK25G AK25H AK62B AK66B AN01G AR00A AR00C AT00B BA02 BA03 BA04 BA07 BA10A BA10C CA07 EJ55 GB90 HB31A JD09A JL00 JL09 JL13C JM01H 4J004 AA05 AA10 AA11 AB01 CA01 CA04 CA05 CB03 CC03 DB01 FA04

Claims (4)

[Claims] 1. A laminated film having a layer having an ultraviolet absorbing function formed in a supporting substrate. 2. The laminated film according to claim 1, wherein the layer having an ultraviolet absorbing function is formed by printing. 3. The laminated film according to claim 1, wherein the supporting substrate is made of one or more of films made of polyolefin or polyvinyl chloride. 4. A pressure-sensitive adhesive sheet for surface protection comprising the laminated film according to claim 1 as a support, and a pressure-sensitive adhesive layer provided on one side of the laminated film.