JPH05331429A - Photosetting type adhesive film - Google Patents

Abstract

PURPOSE:To provide photosetting type adhesive film which comprises the light- transmitting base material, the photosetting adhesive layer and the pressuresensitive adhesive layer, cane readily be peelable from the substrate and never peels off the coat on the substrate surface on peeling. CONSTITUTION:The photosetting type adhesive film comprises (A) a light- transmitting base material which can sufficiently transmit light of 180 to 460nm wavelength and has a thickness of 30 to 150mum (preferably polyethylene terephthalate) and (B) a photosetting type adhesive layer 5 to 40mum thick, consisting of (B1) 100 pts.wt. of rubber or acrylic base polymer, (B2) 1 to 100 pts.wt. of a photopolymerizable compound, preferably a substance having less than 5000 molecular weight and 2 to 6 optically polymerizable carboncarbon double bonds such as trimethylolpropane triacrylate, (B3) 0.1 to 5 pts.wt. of a photopolymerization initiator, such as benzophenone and further, (C) a pressure-sensitive adhesive layer of rubber or acrylic polymer of 0.1 to 2, preferably 0.2 to 1mum thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable pressure-sensitive adhesive film used for surface protection of painted steel sheets and the like.

[0002]

BACKGROUND OF THE INVENTION After attaching an adhesive film having a photo-curable adhesive to an adherend,
It is a surface protection method of irradiating the film with light to cure the adhesive to such an extent that there is almost no adhesiveness in the pasted state, and then peeling it off, thus almost eliminating plastic deformability of the adhesive and increasing cohesive force. A method of improving a surface protective material having excellent non-transferability and workability is disclosed in JP-B-58-308.
No. 09 publication.

However, in the above-mentioned conventional technique, when the adherend is a coated metal plate (steel plate) obtained by coating a metal plate or steel plate with an acrylic, urethane, polyester, melamine-based coating material, etc. Depending on the combination of the pressure-sensitive adhesive and the paint, the pressure-sensitive adhesive film may not be peeled off after being irradiated with light, or the paint on the surface of the adherend may be robbed by the pressure-sensitive adhesive film when the pressure-sensitive adhesive film is peeled off.
This is because the adhesive is cured by light irradiation and the adhesiveness at the interface with the adherend is further increased, and the photosensitive low molecular weight compound in the adhesive reacts with the photosensitive substance in the paint on the surface of the adherend. Or it seems that the cause is binding.

Therefore, an object of the present invention is to provide a light-curable pressure-sensitive adhesive film for surface protection, which can be easily peeled from the surface of an adherend and in which peeling of the coating material on the surface of the adherend is suppressed. That is.

[0005]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that the present invention achieves the above object. That is, the present invention relates to a light-transmitting substrate layer (I) and a pressure-sensitive adhesive layer (II) having photocurability.
A photocurable pressure-sensitive adhesive film having a pressure-sensitive adhesive layer (I
I) A photocurable pressure-sensitive adhesive film having a pressure-sensitive adhesive layer (III) thereon.

The pressure-sensitive adhesive film of the present invention has a structure in which the photocurable pressure-sensitive adhesive layer (II) is further laminated on the base material layer (I) and the pressure-sensitive adhesive layer (III) is further laminated thereon. Is.
Here, the (III) layer is composed of a normal pressure-sensitive adhesive that does not cure by irradiation with light, and this layer is a photocurable adhesive layer (II).
The problem is solved by providing a thin layer on top of. In other words, by providing the (III) layer, the binding force at the interface with the adherend does not increase due to light irradiation, and the photosensitive low molecular weight compound in the photocurable adhesive and the coating on the surface of the adherend It can prevent the photosensitizer contained therein from reacting or binding.

The pressure-sensitive adhesive layer (III) is not particularly limited as long as it is usually used, and examples thereof include rubber-based or acrylic pressure-sensitive adhesives, preferably natural rubber-based or SIS (styrene-isoprene-styrene), SBS (styrene-butadiene-styrene), S
Examples thereof include block copolymers such as EBS (styrene-ethylene / butylene-styrene) and SBR (styrene-butadiene rubber).

The film thickness is usually 0.1 to 2.0 μm, preferably 0.2 to 1.0 μm. When the thickness is less than 0.1 μm, it is difficult to prevent the reaction or bonding between the photosensitive low molecular weight compound in the layer (II) and the photosensitive substance in the coating material on the surface of the adherend, and good peelability cannot be obtained. Or, the paint may be destroyed when the film is peeled off. Also, 2.0
If it is thicker than μm, the adhesion between the (III) layer and the adherend increases due to increased wetting, and good peelability cannot be obtained after light irradiation. Good wettability may not be obtained during lamination.

The base material layer (I) may be light-transmissive,
Generally, it may be made of a material having a property of sufficiently transmitting 180 to 460 nm light, and a transparent plastic film is particularly preferable. Specific examples include those made of polyolefin resins, polyester resins, vinyl chloride resins and the like, and preferably made of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride and the like. The film thickness of the substrate is usually 30 to 150 μm, preferably 40 to 100 μm.
m.

The photocurable pressure-sensitive adhesive layer (II) is a low molecular weight compound having at least two photopolymerizable carbon-carbon double bonds in the molecule, for example, in an ordinary rubber-based or acrylic pressure-sensitive adhesive. (Hereinafter, referred to as a photopolymerizable compound) and a photopolymerization initiator are mixed to form a pressure-sensitive adhesive composition.

The above-mentioned rubber-based or acrylic pressure-sensitive adhesive is a rubber-based polymer such as natural rubber or various synthetic rubbers, or poly (meth) acrylic acid alkyl ester, (meth) acrylic acid alkyl ester and the like. Acrylic polymers such as copolymers with other copolymerizable unsaturated monomers were used as a base polymer, and a polyisocyanate compound, a cross-linking agent such as an alkyl etherified melamine compound, etc. were added to the base polymer as needed. It is a thing. In addition,
The above base polymer may have a photopolymerizable carbon-carbon double bond in the molecule.

The above-mentioned photopolymerizable compound preferably has a molecular weight of usually 10,000 or less, and more preferably, in order that the three-dimensional reticulation of the pressure-sensitive adhesive layer by light irradiation can be efficiently performed. It is preferable to use a polymer having a molecular weight of 5,000 or less and having 2 to 6 photopolymerizable carbon-carbon double bonds in the molecule.

Of the above photopolymerizable compounds, particularly preferable ones are, for example, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate,
Examples thereof include pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate and the like. Examples of other photopolymerizable compounds include 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, and commercially available oligoester acrylate.

As the photopolymerizable compound, one of the above compounds may be used alone, or two or more of them may be used in combination. Moreover, the compounding quantity of a photopolymerizable compound is 1-100 weight part normally with respect to 100 weight part of base polymers, Preferably it is 10-100 weight part.

Further, in order to improve the reactivity, it is preferable to add a photopolymerization initiator. Examples of the photopolymerization initiator include isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, acetophenone diethyl ketal, and benzyl dimethyl ketal.
Examples include α-hydroxycyclohexyl phenyl ketone and 2-hydroxymethyl phenyl propane, and one of these may be used alone or in combination of two or more. The compounding amount of the photopolymerization initiator is usually 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the base polymer.

The thickness of the (II) layer is usually 5 to 40 μm, preferably 5 to 30 μm.

The pressure-sensitive adhesive film of the present invention may be produced by laminating it by a method which has been generally used in the past, for example, (I)
The layer (II) is laminated on the layer by coating, printing or the like, and the layer (III) is laminated by coextrusion or dry laminating. It can also be produced by using a two-layer / three-layer type co-extruder.

[0018]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

Example 1 A compounding composition consisting of 100 parts by weight of butyl acrylate, 7 parts by weight of acrylonitrile and 5 parts by weight of acrylic acid was copolymerized in toluene to obtain an acrylic copolymer having a weight average molecular weight of 300,000. .. To 100 parts by weight of this copolymer, 5 parts by weight of a polyisocyanate compound (Coronate L manufactured by Nippon Polyurethane Company), 50 parts by weight of dipentaerythritol monohydroxypentaacrylate and 1 part by weight of α-hydroxycyclohexyl phenyl ketone were added and mixed. A photocurable pressure-sensitive adhesive composition was prepared. 6 of this composition
A polyethylene film having a thickness of 0 μm was coated on one side so that the thickness after drying was 20 μm, and heated at 90 ° C. for 2 minutes to obtain an adhesive film (A).

Next, 2 parts by weight of the above polyisocyanate compound was added to 100 parts by weight of the natural rubber adhesive to prepare a pressure sensitive adhesive composition. This composition was applied to a 50 μm-thick release-treated polyester film so that the thickness after drying would be 0.5 μm, and an adhesive film (B) was obtained in the same manner as above. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive films (A) and (B) were stuck together and pressure-bonded with a laminator, and the polyester film was peeled off to obtain a pressure-sensitive adhesive film having a three-layer structure.

Example 2 A composition containing 100 parts by weight of butyl acrylate, 7 parts by weight of acrylonitrile and 1 part by weight of 2-hydroxyacrylate was copolymerized in toluene to give a weight average molecular weight.
500,000 acrylic copolymers were obtained. This copolymer 1
3 parts by weight of the polyisocyanate compound used in Example 1 was added to 00 parts by weight to prepare a pressure-sensitive adhesive composition.
This composition was applied to a 50 μm-thick release-treated polyester film so that the thickness after drying would be 1 μm, and heated at 90 ° C. for 2 minutes to obtain an adhesive film (B ′).
This adhesive film (B ') was used as the adhesive film (A) of Example 1.
It was attached to the surface of the photo-curable pressure-sensitive adhesive layer side, and a pressure-sensitive adhesive film having a three-layer structure was obtained in the same manner as in Example 1.

Comparative Example 1 The adhesive film (A) of Example 1 was used as the adhesive film of Comparative Example 1.

Experimental Example 1 The pressure-sensitive adhesive films obtained in the above Examples and Comparative Examples were attached to an adherend (made by Nisshin Steel Co., Ltd., polyester-based paint-coated steel sheet), and 180 ° peeling force (peeling before UV irradiation). The force, that is, the peeling force 1) in Table 1 below was measured. Also, from the base film side of the adhesive film attached to the adherend, ultraviolet irradiation (150 W) was performed for 5 seconds with a high pressure mercury lamp (40 W / cm).
After irradiation with 0 mJ / cm ² ), the 180 ° peeling force (peeling force after irradiation with ultraviolet rays, that is, peeling force 2 in Table 1 below) was measured. In addition, 180 degree peeling force is 23 ℃, 65% RH,
The tensile speed was 300 mm / min, and the tensile strength was measured with a Tensilon tensile tester.

Further, the adhesive film attached to the adherend, which was irradiated with ultraviolet rays, was applied with pressure of 20 kg / cm ² at 60 ° C. for 8 hours.
After being stored at 0% RH for 1 week, it was peeled off from the adherend. The state of the coated surface of the adherend after the peeling of the adhesive film was observed. The results are shown in Table 1.

[0025]

[Table 1]

[0026]

The photocurable pressure-sensitive adhesive film of the present invention has an effect that it can be easily peeled from the surface of an adherend and that the coating material on the surface of the adherend is not peeled off at the time of peeling. ..

Claims (2)

[Claims] 1. A photocurable pressure-sensitive adhesive film comprising a light-transmissive substrate layer (I) and a photocurable pressure-sensitive adhesive layer (II), wherein a pressure-sensitive pressure-sensitive adhesive layer is provided on the pressure-sensitive adhesive layer (II). A photocurable pressure-sensitive adhesive film having (III). 2. The pressure-sensitive adhesive layer (III) has a thickness of 0.1 to 10.
It is 2.0 micrometers, The photocurable adhesive film of Claim 1 characterized by the above-mentioned.