JPS61281163A - Adhesive composition for surface-protection material - Google Patents

Abstract

PURPOSE:To provide the titled composition composed mainly of a specific hydrogenated block copolymer of a styrene (homolog) and a conjugated diene, suitable for the surface-protection sheet of metal plate, plastic plate, etc., and having low temperature dependency of adhesivity. CONSTITUTION:A block copolymer of the type A/B/A or a mixture of A/B/A and A'/B' [A and A' are styrene (homolog) block; B and B' are conjugated diene polymer block] is hydrogenated, and the obtained hydrogenated copolymer is used as a main component of the objective composition having a storage shear modulus of <=2.0X10<7>dyne/cm<2> at 1Hz and 0 deg.C and >=2.0X10<5>dyne/cm<2> at 1Hz and 60 deg.C.

Description

Detailed Description of the Invention The present invention is applicable to metal plates such as stainless steel plates, aluminum plates, copper plates, decorative plates, ABS plates, acrylic plates, styrene plates, glass plates, vinyl chloride plates, etc. (hereinafter referred to as protective plates).
A surface protection material used for surface protection sheets or tapes (hereinafter referred to as "Surface Protection Sort") that has extremely small differences in adhesive strength due to temperature changes during lamination, and does not leave adhesive residue even when peeled off at high temperatures. The present invention relates to an adhesive composition.

[Conventional technology]

Traditionally, acrylic adhesives and rubber adhesives based on rubbers such as natural rubber and polyisobutylene have been widely used as adhesives for surface protection materials, but these are solvent-based. Because of this, there were problems with fire danger, pollution, and economic efficiency.

Recently, in order to solve these problems, thermal melting type or
Highly concentrated adhesives have been developed and are used for postal applications.

Typical such adhesives are those whose main components are block copolymers of styrene/butadiene and styrene/isoprene, but these have a large temperature-sensitive ratio of adhesive strength and have the following properties: There is a problem.

■ The temperature of the protected board is around 0℃ in winter, and 60℃ to 70℃ in summer when it is left outdoors or mounted in a car.
However, when the protected plates are bonded together at different temperatures, there is a significant difference in adhesive strength.

■ Also, if it is removed from the protected board at a relatively high temperature, the adhesive will have softened, resulting in cohesive failure and adhesive residue.

In addition, there are other problems such as extremely poor weather resistance, and the reality is that surface protection materials using Pronk polymer adhesives cannot be used in practice or can only be used for a limited number of applications. be.

[Problem that the invention seeks to solve]

An object of the present invention is to provide an adhesive composition for a surface protection material that has extremely small differences in adhesive strength due to temperature changes and does not leave adhesive residue even when peeled off at high temperatures.

[Means for Solving the Problems] As a result of studying various materials in order to solve the above technical problems, the present inventors found that A/B/A or A/B/
A and A'/B' (However, A and 8 are each styrene or a styrene homolog block, B and B are
By using an adhesive composition whose main component is a hydrogenated copolymer (each representing a conjugated diene polymer block) and which has a specific shear storage modulus (hereinafter simply referred to as storage modulus), it is possible to It has an extremely stable adhesive strength regardless of the temperature difference between the protected plates when mating, and does not leave adhesive residue on the protected plates even if removed at relatively high temperatures.
The inventors discovered that an adhesive composition for surface protection materials can be obtained and completed the present invention.

That is, the present invention relates to the general formula A/B/A or A/B/A and A'
The main component is a block copolymer obtained by hydrogenating a mixture of /B'(ASA', B and B' have the same meanings as above), and
The storage modulus at 1H2 [G゛0°C (lHz)] is 2. OX 107dyne/cj or less and 60℃
Storage modulus CG' at 1H2 at 50°C (IH2)
2. The adhesive composition for surface protection material is composed of a composition having OX 10' dyne/- or more.

A in A/B/A used in the present invention is styrene or a styrene homolog polymer block, and its preferable molecular weight is about 1,000 to 100,000,
Further, a preferable glass transition temperature is 7°C or higher. Also,
B in A/B/A is a conjugated diene (butadiene, isoprene, etc.) block, and the preferred molecular weight is 10,
000 to 500,000, and its preferable glass transition temperature is -20°C or lower. As the conjugated diene block, butadiene is particularly preferred in terms of economy and properties. The preferred weight ratio of A and B is A/B-5/9.
5 to 50150.

In the present invention, in addition to A/B/A, A''/B'' may be further blended for the purpose of lowering the storage modulus. Here, A' and B' are the same as A and B, respectively, and the preferred weight ratio of A and B is A'/B' = 5150.
~5015.

In addition, as for the degree of hydrogenation, it is desirable that the conjugated diene block is almost selectively hydrogenated.
60% or more of the diene component of the copolymer, preferably 80% or more
% or more is preferably hydrogenated. If the degree of hydrogenation is less than 60%, it will be difficult to balance the elastic modulus at high temperatures and the elastic modulus at low temperatures, and it will be difficult to obtain a composition that has stable adhesive strength with little change in extreme temperature properties. be.

In the present invention, the storage modulus is controlled within the above range, and the following may be used for such control as necessary. That is, rosin resins, terpene resins (α-pinene, β-pinene, etc.), aliphatic petroleum-based resins (piperylene, isoprene, etc.), alicyclic petroleum-based resins (cyclopentadiene, etc.), aromatic resins (alkylbenzene, etc.) ) and other tackifiers. These include process oil, polyester plasticizer, the above-mentioned tackifier with a low softening point, various softeners such as liquid rubber, and various fillers such as calcium carbonate, warping force, carbon, and clay.

These various additives have G'0℃ (1H2) of 2 and O
X 10' dyne/cfl! Below and G゛60
℃(1H2) is 2. OX 10' dyne/c4
They may be mixed in any proportion as long as they are blended within this range. G゛0℃(1H2) is 2. OX10'
If it exceeds dyne/a, sufficient adhesion strength at low temperatures cannot be obtained, while G'60'C (lHz) is 2.
If the adhesive layer is less than 0' dyne/c+4, the adhesive layer will soften too much at high temperatures, and if the temperature of the protected board is high, the adhesive force will be too high to be easily removed, and cohesive failure will occur, causing damage to the protected board. Easy to leave adhesive residue.

The block polymer before hydrogenation is produced by a conventional method. For example, a styrene (homogeneous) pasting polymer is produced using 5ec-butyllithium or the like in a hydrocarbon solvent (e.g., cyclohexane), and then a conjugated diene is added to create a styrene-conjugated diene die plotter.
Styrene is further added to this to form a triblock, or a bifunctional or more functional coupling agent is added to form a triblock or radial teleblock type block polymer. Alternatively, the end of the Gouiblock may be inactivated to make the Gouiblock, and the product may be used as it is.

The method for hydrogenating the conjugated dienebrosulfate polymer produced in this way is to dissolve the polymer in an inert hydrocarbon solvent, add cobalt or nickel, etc. reduced using a catalyst such as an alkyl aluminum, and then 2
For example, 5 to 40 kg/ca at a temperature of 5 to 50°C
The reaction is carried out by applying pressure with 1 liter of hydrogen and reacting for about 10 to 60 minutes. The presence or absence of vinyl groups in the product produced by hydrogenation can be easily determined by infrared analysis.

Further, in the adhesive composition, various commonly used materials such as various rubbers, ultraviolet absorbers, and anti-aging agents may be used as necessary within the scope of the present invention.

The adhesive composition of the present invention can be used as a surface protection film by forming an adhesive layer on a support. Although any known support may be used, plastic films are particularly preferred. Specifically, polyethylene, polypropylene, polyester, polyvinyl chloride, etc. are used. The support may be subjected to known undercoating treatment, back surface treatment, etc., if necessary.

The thickness of each layer of the surface protection film using the adhesive composition of the present invention is preferably as follows.

That is, the adhesive layer preferably has a thickness of 200 μm or less, more preferably 5 to 50 μm, and the support layer has a thickness of 300 μm or less, preferably 10 to 100 μm.

Examples of methods for manufacturing the surface protection film include the following methods.

(2) A method of coating a support with an adhesive composition preliminarily dissolved in a solvent such as toluene at a predetermined concentration by roll coating.

■ Co-extrusion method with thermoplastic resin using inflation, T-die, etc.

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

[Action/Effect]

The adhesive composition of the present invention shows extremely little difference in adhesive strength with respect to changes in the temperature of the object to be protected, and does not leave any adhesive residue on the object even if it is peeled off at high temperatures. Therefore, the surface protection film produced using the adhesive composition of the present invention can be used even on adherends subjected to extremely harsh conditions.

〔Example〕

Example 1 On the treated surface of a polyethylene film subjected to corona treatment,
Polymer 1 (100 parts by weight) prepared as follows,
Alicyclic petroleum resin S, P, 100°C (100 parts by weight) Low softening point alicyclic petroleum resin S, P 20°C (100 parts by weight)
Apply an adhesive that is dissolved in 600 parts of toluene, and
It was dried at ℃×5 minutes.

A tape with a 15 μm thick adhesive layer was produced.

(Preparation of Polymer 1) 40 g of styrene and 400 g of cyclohexane are placed in an autoclave, and the autoclave is sufficiently purged with nitrogen. 0.003 mol of sec-butyllithium dissolved in schifhexane is added.

■ React at 60°C for 1 hour.

(4) Add 400 g of butadiene and 2000 g of cyclohexane to this reaction system, and continue the reaction at 60°C for 2 hours.

■ After the reaction, add 40g of styrene and 4g of cyclohexane.
00g was put into the reaction system and reacted at 60°C for 1 hour.

(2) An SBS block polymer was prepared by the above method.

■ Nickel acetyl acetonate as a catalyst1.
5 mmol of triethylaluminum and 3 mmol of triethylaluminum were reacted in 500 d of cyclohexane at 25° C. for 10 minutes, and the mixture was added to the reaction system (2).

(2) The autoclave was pressurized with hydrogen to 30 kg/c+J, the reaction temperature was raised to 50°C, and hydrogenation was stopped after 20 minutes.

■ Table 1 shows the results of analyzing the finished polymer.

Example 2 A composition kneaded with the formulation shown in the Example 2 column of Table 2,
A tape was prepared by coextrusion molding with polyethylene (density 0.923, Mel I index -2.5), in which a 10 μm thick adhesive layer was provided on an 80 μm polyethylene film.

Polymer 2 was prepared according to Polymer 1.

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

Polymer 3 was prepared according to Polymer 1.

Comparative examples 1 to 3 It was prepared in the same manner as in Example I.

Polymer 4 was made into eight molds in the same manner as Polymer 1.

Experimental Example 1 0°C and 6°C for polyvinyl chloride boards (PVC boards) and melamine boards for the samples obtained in the above Examples and Comparative Examples
The adhesive strength at 0° C. and the presence or absence of adhesive residue at this temperature were examined, and the results are shown in Table 2.

The test method is as follows.

(Test method) Test pieces of adhesive crab PVC board (center surface roughness Ra -2,6μ) and melamine board (center surface roughness Ra -1,6μ) were stored at 0°C and 60°C for 1 hour, and the atmosphere The samples were bonded together below, and after being left for 1 hour at 20° C. x 65 (%), a 180 degree peel test was conducted.

The peeling speed was 300■■/win.

Adhesive residue: Attach the sample to the above adherend at 60°C,
After standing for a period of time, the adhesive was peeled off at a speed of 300 w/min under the same atmosphere and visually inspected for the presence or absence of adhesive residue.

(Margin below)

Claims (2)

[Claims] (1) A/B/A or a mixture of A/B/A and A'/B' (A and A' are each a styrene or styrene homologue block, B and B' are each a conjugated diene polymer block The main component is a block copolymer obtained by hydrogenating 1H_2 at 0°C and has a shear storage modulus of 2.0 x 10^7 dyne/cm^2 or less and 6
Shear storage modulus at 1Hz at 0℃ is 2.0×10^
An adhesive composition for a surface protection material, characterized in that the adhesive composition is 5 dyne/cm^2 or more. (2) A/B/A or A/B/A and A'/B' (A, A
2. The adhesive composition for a surface protection material according to claim 1, wherein the mixture (wherein ', B and B' have the same meanings as defined above) is a hydrogenated block copolymer of styrene and butadiene.