JPH0689312B2 - Adhesive composition for surface protection material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a metal plate such as a stainless plate, an aluminum plate, a copper plate or a decorative plate, an ABS plate, an acrylic plate, a styrene plate, a glass plate, a vinyl chloride plate, etc. (hereinafter referred to as a protective plate).
For surface protection sheet or tape (hereinafter referred to as surface protection sheet), which has a very small difference in adhesive strength due to temperature change during lamination and does not cause adhesive residue even when peeled at high temperature The present invention relates to an adhesive composition.

[Conventional technology]

Conventionally, as an adhesive used for a surface protective material, an acrylic adhesive or a rubber adhesive mainly composed of a rubber such as natural rubber or polyisobutylene has been widely used, but these are solvent-based ones. Therefore, there was a problem in fire danger, pollution, and economical efficiency.

Recently, in order to solve such problems, heat fusion type or
High-concentration adhesives have been developed and are partially used.

As a typical example of such an adhesive, those containing a block copolymer of styrene / butadiene and styrene / isoprene as a main component are known. However, these have a large temperature-sensitive adhesive strength ratio and are as follows. There is a problem.

The temperature of the plate to be protected rises to about 0 ° C in winter and to 60 ° C to 70 ° C in the summer when it is left outdoors or mounted on a vehicle. When bonded under different conditions, the difference in adhesive strength is remarkable.

Further, when peeled off from the plate to be protected at a relatively high temperature, the adhesive material is softened, causing cohesive failure and adhesive residue.

In addition, due to problems such as extremely poor weather resistance, the surface protection material using the above block polymer-based adhesive cannot be practically used or can be used for only a small number of applications. Is.

[Problems to be solved by the invention]

An object of the present invention is to provide an adhesive composition for a surface protective material, which has a very small difference in adhesive force due to temperature change and does not cause adhesive residue even when peeled at high temperature.

[Means for solving problems]

The present inventors have studied various materials to solve the above technical problems, and as a result, A / B / A or A / B / A and A ′ /
B '(wherein A and A'represent styrene or styrene homolog blocks, respectively, and B and B'respectively represent conjugated gen polymer blocks) is mainly composed of a copolymer obtained by hydrogenation and is subjected to specific shear storage. By using an adhesive composition in the range of elastic modulus (hereinafter simply referred to as storage elastic modulus), the adhesive strength is extremely stable and relatively high regardless of the temperature difference of the protected plates at the time of bonding. The present invention has been completed by finding that an adhesive composition for a surface protective material can be obtained which does not leave an adhesive residue on a plate to be protected even when peeled off at a high temperature.

That is, the present invention provides a block copolymer obtained by hydrogenating a compound of the general formula A / B / A or a mixture of A / B / A and A '/ B' (A, A ', B and B'have the same meanings as described above). , The storage elastic modulus at 0 ° C at 1 Hz [G'0 ° C (1Hz)] is 2.0 × 10 ⁷ dyne / cm ²
Storage modulus below 1 G at 60 ° C [G'60 ° C
(1 Hz)] is 2.0 × 10 ⁵ dyne / cm ² or more.

A in A / B / A used in the present invention is a styrene or styrene homolog polymer block, but its preferable molecular weight is about 1,000 to 100,000, and its preferable glass transition temperature is 7 ° C or higher. Further, B in A / B / A is a conjugated diene (butadiene, isoprene, etc.) block, but a preferred molecular weight is 10,000 to 500,000, and a preferred glass transition temperature thereof is −20 ° C. or lower as a conjugated diene block. Is particularly preferably butadiene in terms of economy and properties. The preferred weight ratio of A and B is A /
B = 5/95 to 50/50.

In the present invention, in addition to A / B / A, A '/ B' may be further blended for the purpose of lowering the storage elastic modulus. Where A ′ and B ′ are the same as A and B, respectively,
The preferred weight ratio of A and B is A '/ B' = 5/50 to 50/5.

Further, as the degree of hydrogenation, it is desirable that the conjugated diene block is almost selectively hydrogenated,
It is desirable that 60% or more, preferably 80% or more, of the diene component of the copolymer be hydrogenated. When the degree of hydrogenation is less than 60%, it becomes difficult to balance the elastic modulus at high temperature and the elastic modulus at low temperature, and it is difficult to obtain a composition having stable adhesive strength with little change in temperature-sensitive characteristics. is there.

In the present invention, the storage elastic modulus is controlled within the above range, and the following is used for such control, if necessary. That is, rosin-based resin, terpene-based resin (α-pinene, β-pinene, etc.), aliphatic petroleum-based resin (piperine, isoprene, etc.), alicyclic petroleum-based resin (cyclopentadiene, etc.), aromatic-based resin (alkylbenzene, etc.) Various tackifiers such as. Examples include process oils, polyester-based plasticizers, tackifiers having a low softening point, various softening agents such as liquid rubber, various fillers such as calcium carbonate, silica, carbon and clay.

These various additives have a G'0 ° C (1 Hz) of 2.0 × 10 ⁷ dyn.
If the composition is such that it is not more than e / cm ² and G'60 ° C. (1 Hz) is in the range of 2.0 × 10 ⁵ dyne / cm ² , they may be mixed at any ratio. If G'0 ° C (1Hz) exceeds 2.0 × 10 ⁷ dyne / cm ² , sufficient adhesive strength at low temperature cannot be obtained, while G'60 ° C (1H
When z) is less than 2.0 × 10 ⁵ dyne / cm ² , the adhesive layer is too soft at high temperature, and when the temperature of the plate to be protected is high, the adhesive force is too high to easily peel off and cohesive failure. Is likely to occur, leaving an adhesive residue on the plate to be protected.

The block polymer before hydrogenation is produced by a conventional method. For example, in a hydrocarbon-based solvent (for example, cyclohexane), a living polymer of styrene (a homologue) is produced using sec-butyllithium, etc., and then a conjugated diene is added to form a styrene-conjugated diene diblock,
Styrene is further added thereto to form a triblock, or a bifunctional or higher functional coupling agent is added to form a triblock or radial teleblock type block polymer. Alternatively, the ends of the die block may be inactivated and the die block may be used as it is.

As a method for hydrogenating the conjugated diene block polymer thus obtained, the polymer is dissolved in an inert hydrocarbon solvent, and cobalt or nickel reduced by using a catalyst such as alkylaluminum is added, and usually 25
It is carried out by applying pressure at a temperature of -50 ° C, for example, with hydrogen of 5-40 kg / cm ² and reacting for about 10-60 minutes. The presence or absence of vinyl groups in the product produced by hydrogenation can be easily examined by infrared analysis.

Further, in the adhesive composition, if necessary, various materials such as various rubbers, UV absorbers, and antioxidants that are commonly used may be used within the range not deviating from the gist of the present invention.

The adhesive composition of the present invention can be made into a surface protective film by forming an adhesive layer on a support. It is sufficient to use a known support as the support, but a plastic film is particularly preferable. Specifically, polyethylene, polypropylene, polyester, polyvinyl chloride or the like is used. The support may be subjected to known undercoating treatment, back treatment, etc., if necessary.

The thickness of each layer of the surface protective film using the adhesive composition of the present invention is preferably as follows. That is, the adhesive layer is preferably 200 μm or less, more preferably 5 to 50 μm.
μm, the support layer is 300 μm or less, preferably 10 to 1
It is 00 μm.

Examples of the method for producing the surface protective film include the following methods.

A method in which an adhesive composition previously dissolved in a solvent such as toluene at a predetermined concentration is coated on a support by roll coating.

A method of co-extruding with a thermoplastic resin by inflation, T-die or the like.

A method of coating an adhesive layer on a support with an extruder.

[Action / effect]

The adhesive composition of the present invention has an extremely small difference in adhesive strength with respect to temperature change of the object to be protected, and does not cause adhesive residue on the adherend when peeled at a high temperature. Therefore, the surface protective film produced by using the adhesive composition of the present invention can be used even for an adherend placed under extremely severe conditions.

〔Example〕

Example 1 On the treated surface of a polyethylene film that had been subjected to corona treatment,
Polymer 1 (100 parts by weight) prepared as follows, alicyclic petroleum resin SP 100 ° C (100 parts by weight), low softening point alicyclic petroleum resin S.P 20 ° C (100 parts by weight) was dissolved in 600 parts of toluene. The adhesive was applied and dried at 100 ° C. for 5 minutes. A tape having a 15 μm thick adhesive layer was prepared.

(Preparation of Polymer 1) 40 g of styrene and 400 g of cyclohexane are put into an autoclave, and nitrogen substitution is sufficiently performed.

0.002 of secondary butyllithium dissolved in cyclohexane
Add 3 moles.

 React at 60 ° C for 1 hour.

400 g of butadiene and 2000 g of cyclohexane are added to the reaction system, and the reaction is further continued at 60 ° C. for 2 hours.

After the reaction, 40g of styrene and 400g of cyclohexane
Is charged into the reaction system and reacted at 60 ° C. for 1 hour.

The SBS block polymer was prepared by the above method.

As a catalyst, nickel acetyl-acetonate 1.5
Mmol and 3 mmol of triethylaluminum were reacted in 500 ml of cyclohexane at 25 ° C. for 10 minutes and added to the reaction system.

The inside of the autoclave was pressurized with hydrogen to 30 kg / cm ² , the reaction temperature was raised to 50 ° C., and the hydrogenation was stopped after 20 minutes.

Table 1 shows the result of analysis of the resulting polymer.

Example 2 A composition kneaded with the composition shown in the column of Example 2 in Table 2,
Polyethylene (density 0.923, melt index = 2.5)
And co-extruded into an 80μ polyethylene film
A tape provided with an adhesive layer having a thickness of 10 μm was produced.

Polymer 2 was prepared according to Polymer 1.

Example 3 In the same manner as in Example 1, the composition shown in the column of Example 3 in Table 2 was used to form an adhesive layer on a polyester film.

Polymer 3 was prepared according to Polymer 1.

Comparative Examples 1 to 3 were prepared in the same manner as in Example 1.

Polymer 4 was prepared according to Polymer 1.

Experimental Example 1 Polyvinyl chloride plate (vinyl chloride plate) and melamine plate at 0 ° C. and 60 for the samples obtained in the above Examples and Comparative Examples.
The adhesive strength at ° C and the presence or absence of adhesive residue at that temperature were examined, and the results are shown in Table 2.

The test method is as follows.

(Test method) Adhesive strength: Test pieces of a PVC plate (center surface roughness Ra = 2.6μ) and a melamine plate (center surface roughness Ra = 1.6μ) were tested at 0 ° C and 60 ° C.
The sample was attached at 20 ° C. for 1 hour, and the sample was laminated in that atmosphere, left at 20 ° C. × 65 (%) for 1 hour, and then subjected to a 180 ° peeling test.

The peeling speed is 300 mm / min.

Adhesive residue: A sample was attached to the adherend at 60 ° C., left for 1 hour, and then visually inspected for adhesive residue when peeled off at a speed of 300 mm / min in the same atmosphere.

(1) Polymer used (2) Result

Claims (2)

[Claims] 1. A / B / A or a mixture of A / B / A and A '/ B' (A and A'are styrene or a styrene homolog block, respectively, and B and B'are conjugated gen heavy chains, respectively. (Showing a united block) is a main component of a hydrogenated block copolymer and has a shear storage elastic modulus at 0 ° C. of 1 Hz of 2.0 × 10 ⁷ d.
An adhesive composition for a surface protective material, which has a shear storage elastic modulus at 60 ° C. at 1 Hz of 2.0 × 10 ⁵ dyne / cm ² or less and yne / cm ² or less. 2. A / B / A or A / B / A and A '/ B' (A, A ', B
The adhesive composition for a surface protective material according to claim 1, wherein the mixture of (and B ′ has the same meaning as above) is obtained by hydrogenating a block copolymer of styrene and butadiene.