JPH0762312A - Pressure-sensitive adhesive composition for surface protective material and surface protective material - Google Patents

Abstract

PURPOSE:To obtain a pressure-sensitive adhesive composition for a surface protective material having good adhesiveness when sticking, undergoing very little change in adhesive force with time after sticking, and having practical weatherability and produce the surface protective material by using it. CONSTITUTION:This composition contains 100 pts.wt. polymer having isobutylene units as the principal constituent and 3-30 pts.wt. wax having an acid value of 3 to 90. The surface protective material has a layer of this composition on a base material.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is used for a surface protection sheet or tape (hereinafter referred to as a surface protection material) for coated plates, metal plates, resin plates, etc. The present invention relates to a pressure-sensitive adhesive composition for a surface protective material, which has a very small change in adhesive strength with time after laminating and has practical weather resistance, and a surface protective material using the same.

[0002]

2. Description of the Related Art Conventionally, acrylic adhesives and rubber adhesives mainly composed of rubber such as natural rubber and polyisobutylene have been used as adhesives used for surface protective materials such as painted plates, metal plates and resin plates. It is widely used, and ethylene-vinyl acetate copolymer (EVA) adhesive, styrene / butadiene / styrene block copolymer (SBS) adhesive, and styrene / isoprene / styrene block copolymer (SIS) adhesive are used. ing. However, these have the following problems.

(1) Since the acrylic adhesive itself has a high polarity, the adhesive strength after attaching the surface protective material is extremely large, and when the surface protective material is peeled from the adherend, the peeling strength is large. When workability is extremely poor and extremely severe, adhesive residue is left on the surface of the adherend. (2) Although the adhesive strength of the polyisobutylene / block copolymer adhesive is smaller than that of the acrylic adhesive, the peeling work is not so easy. (3) Natural rubber-based, EVA-based, SIS-based, and SBS-based adhesives tend to deteriorate in a short time due to sunlight, etc., so if the surface protection material is exposed outdoors during transportation or construction, the adhesive will deteriorate. There is a problem of weather resistance that the remainder easily occurs. (4) EVA-based adhesive is a heat-bonding type, and if the surface of the adherend has some irregularities, a good initial adhesive force cannot be obtained by pressure sensing.

In order to improve the above (1) and (2), it is known that various surfactants are added to the adhesive. Since such a surfactant exerts its effect when it exists at the interface with the adherend, it is effective when the adherend is a metal plate. However, when the adherend is a coated plate coated with paint, the molecular weight of these surfactants is as small as several tens to several hundreds, so that the transfer of the adherend from the adhesive to the paint after attachment is small. Occur. As a result, since the surfactant does not exist at the interface, there is a problem that there is no sustainability for suppressing an increase in adhesive force. Further, when a surfactant is added to a rubber adhesive having a low polarity, there is a problem that the surface of an adherend is easily contaminated due to poor compatibility.

As a measure for improving the above (3), the addition of various antiaging agents, ultraviolet absorbers, etc. has been studied, but the characteristics of the surface protective material are insufficient. Further, as an improvement measure of the above (4), the adhesive is further softened by adding a larger amount of a tackifier, a process oil or the like, but the cohesive force is lowered and the adhesive is liable to remain. However, there is a problem that weather resistance is also reduced. In any case, the current situation is that sufficient characteristics have not been obtained.

[0006]

The object of the present invention is to have good adhesiveness at the time of laminating, to have a very small change with time in the adhesive force after laminating, and to have practical weather resistance. A pressure-sensitive adhesive composition for a surface protective material and a surface protective material.

[0007]

The present invention was developed to achieve the above object. That is, the present invention is a pressure-sensitive adhesive composition for a surface protective material, which contains 3 to 30 parts by weight of a wax having an acid value of 3 to 90 with respect to 100 parts by weight of a polymer having an isobutylene unit as a main component. It is also a surface protective material having a layer made of the pressure-sensitive adhesive composition on a substrate.

Examples of the polymer having an isobutylene unit as a main component used in the adhesive composition of the present invention include polyisobutylene, a random copolymer of isobutylene and normal butylene, a copolymer of isobutylene and isoprene (regular butyl rubber, chlorine). Butyl rubber, brominated butyl rubber, partially crosslinked butyl rubber, etc.), or vulcanized or modified products (modified with functional groups such as hydroxyl group, carboxyl group, amino group, epoxy group) and the like, preferably poly Isobutylene or a random copolymer of isobutylene and normal butylene. Where "main component"
Means that the proportion of isobutylene units in the entire polymer is 5
It is preferably 0% by weight or more, and particularly preferably 80% by weight or more.

A polymer having an isobutylene unit as a main component has an appropriate viscoelasticity in the room temperature range and has almost no unsaturated double bond in the molecule, so that an adhesive composition using the polymer is used. Can have good initial adhesion and weatherability.

The wax used in the adhesive composition of the present invention may be liquid or solid, and specific examples thereof include low molecular weight polyethylene wax and low molecular weight polypropylene wax which are synthetic waxes. A low molecular weight polyethylene wax is preferred.

In the present invention, the acid value of the wax must be 3 to 90 (KOHmg / g, JIS K5902), and preferably 10 to 70. Therefore, an oxidation-modified wax obtained by graft-polymerizing dicarboxylic acid, acrylic acid, maleic acid or the like on the above wax or by heating and oxidizing it in the presence of oxygen is used.

When the acid value is less than 3, the wax has a small number of polar groups, so that the adsorbability / affinity of the wax with respect to the adherend becomes small. As a result, the wax does not come out to the interface after sticking, and the adhesive is aged over time. The effect of suppressing the increase in force cannot be obtained. Those having an acid value of more than 90 have too large adsorptivity / affinity with respect to the adherend, so that the wax sticks out too much at the interface to lower the initial adhesiveness, and good laminating properties cannot be obtained.

Further, in the adhesive composition, it is necessary to add 3 to 30 parts by weight of the oxidized wax to 100 parts by weight of the polymer containing the isobutylene unit as a main component, and 3 to 20 parts by weight. It is preferable to contain it. If the amount of the oxidized wax added is less than 3 parts by weight, the effect of suppressing the increase in adhesive strength over time cannot be obtained, and if it exceeds 30 parts by weight, the amount of wax that appears at the interface is too large and the initial adhesiveness decreases. Good laminating properties cannot be obtained.

The molecular weight of these waxes is usually 1,00.
It is 0 to 10,000, and even if the adherend is a coated plate, the wax does not migrate from the adhesive composition to the paint of the adherend after the application.

The oxidized wax is used to suppress the increase in the adhesive force with the passage of time, but when it is blended with the polymer having the above isobutylene unit as the main component,
The effect most often appears.

Further, in the adhesive composition of the present invention, various materials such as commonly used antiaging agents and ultraviolet absorbers may be used depending on the purpose within the range not deviating from the gist of the present invention.

Further, a surface protective material can be prepared by forming the above adhesive composition as an adhesive layer on the following substrate.

As the base material of the surface protective material, conventionally known ones are used, and examples thereof include a polyolefin film and the like, preferably a polypropylene film, a polyethylene film, or a film composed of a blend thereof. If necessary, these films may be subjected to an adhesion treatment (corona treatment, undercoat treatment, etc.) or a back treatment.

In the surface protective material, the thickness of the adhesive layer is preferably 1 to 200 μm, more preferably 1 to 5 μm.
0 μm, and the thickness of the substrate is preferably 5 to 300 μm.
m, more preferably 10 to 100 μm.

The surface protective material can be easily produced, for example, by dissolving the adhesive composition in an organic solvent and applying it on a substrate by a conventional method. Further, it can be easily produced by melt co-extrusion of the polyolefin resin as the base material and the adhesive composition.

[0021]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention. All parts in the text refer to parts by weight.

Examples 1 and 2 and Comparative Examples 1 to 11 As a base material, a 40 μm polypropylene / polyethylene blend film (composition ratio 70 /
30), an adhesive composition having the composition shown in Table 1 was applied to this corona-treated surface by a solution coating using a roll coater so that the solid content (film thickness after drying) was 5 μm, and the adhesive composition was applied at 80 ° C. for 2 hours.
Minute drying was performed to prepare a surface protective material.

[0023]

[Table 1]

Experimental Example 1 The surface protective material was laminated on a melamine-based coated plate using a laminator (laminating pressure 70 N / cm, laminating speed 5 m / min), and the adhesion and weather resistance tests were conducted as follows. I went. The results are shown in Table 2.

(1) Adhesive strength After 30 minutes from application of the surface protective material, the adhesive strength measured under the conditions of a peeling angle of 180 ° and a pulling speed of 0.3 m / min was used as an initial value, and a heating acceleration test at 70 ° C. for 3 days (Arrhenius The adhesive force was measured in the same manner as above even after the conversion by the formula, which corresponds to about 1 year at room temperature.

(2) Weather resistance A sample was fixed outdoors and an outdoor exposure test was conducted. 10, 20, 30, 90 days after the exposure, the surface protective material was peeled off, and the presence or absence of adhesive residue / contamination at that time was examined. When no adhesive residue / contamination was observed, it was evaluated as ◯, and when adhesive residue / contamination was observed, it was evaluated as x.

[0027]

[Table 2]

[0028]

EFFECTS OF THE INVENTION According to the present invention, a feeling for a surface protective material which has good adhesiveness at the time of laminating, has a very small change with time of the adhesive strength after laminating, and has practical weather resistance. A pressure-sensitive adhesive composition and a surface protective material can be provided, and their industrial value is great.

Claims (2)

[Claims] 1. Wax 3 to 30 having an acid value of 3 to 90 per 100 parts by weight of a polymer having an isobutylene unit as a main component.
A pressure-sensitive adhesive composition for a surface protective material, which comprises parts by weight. 2. A surface protective material having a layer comprising the pressure-sensitive adhesive composition according to claim 1 on a substrate.