JPS61255970A - Adhesive composition for surface protective material - Google Patents

Abstract

PURPOSE:To obtain an adhesive for surface protective material, which little undergoes an increase in adhesion with the lapse of time and reduces the amount of a plasticizer migrating from a material to be protected, by blending a compd. contg. an aliph. double bond with a hydrogenated block copolymer. CONSTITUTION:An adhesive compsn. consists of 100pts.wt. block copolymer (a) obtd. by hydrogenating A/B/A or a mixture of A/B and A'/B' (wherein, A, A' are each polymerized styrene block or polymerized block composed of a styrene block or polymerized block composed of a styrene homolog; B, B' are each polymerized conjugated diene block) and 20-400pts.wt. compd. (b) contg. an aliph. double bond and having a bomine value of 15 or below accord ing to JIS K2421 and a tackifying and/or polymer-softening properties. The copolymer (a) is hydrogenated to such an extent that the conjugated diene blocks are selectively hydrogenated, or at least 60% of the diene moiety of the copolymer is hydrogenated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to resin boards (polyvinyl chloride boards, acrylic boards, polycarbonate boards, etc.), painted boards (polyvinyl chloride painted boards, acrylic painted boards, melamine painted boards, etc.) This invention relates to an adhesive composition for a surface protection sheet, film, or tape (hereinafter referred to as a surface protection material) that is used by adhering it to an object to be protected, such as the following.

(Prior art) Traditionally, acrylic adhesives and rubber adhesives mainly made of rubber such as natural rubber or polyisobutylene have been widely used as adhesives for surface protection films for resin boards or painted boards. , some EVA type, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-″″″″ type′°″ copolymer (SI S
) type adhesives etc. are also used. These devices have the following problems.

+11 Acrylic adhesives have an extremely high ability to increase adhesive strength to polar plastic materials such as polyvinyl chloride, acrylic, and polycarbonate, and when peeling the surface protection material from the object to be protected, workability is reduced due to the strong peeling force. (2) Rubber-based adhesives such as polyisobutylene and natural rubber can cause adhesive residue when laminated to polyvinyl chloride boards, etc. The plasticizer in the protector migrates into the adhesive, causing a decrease in cohesive force and leaving adhesive residue when peeled off.Furthermore, (31For resin-based adhesives such as EVA-based adhesives, the above (1)
In addition to the above drawbacks, if the adherend has a rough surface, the initial adhesion strength is low and spontaneous peeling occurs during storage.

(4) Diene block polymers such as SBS and SIS have a drawback in weather resistance.

As a means to improve the above t1), it is known that various surfactants are added to the adhesive, but the surfactant remains on the surface of the adherend, causing cissing during printing, for example.
Further, when the object to be protected is made of polyvinyl chloride, acrylic, or polycarbonate, there is a problem that the effect of controlling the increase in adhesive strength is extremely small.

In addition, as a measure to improve (2) above, measures such as increasing the molecular weight of the base polymer and increasing the crosslinking density are being considered, but it is said that such measures will significantly reduce the adhesion to the protected object. There's a problem.

Furthermore, as a measure to improve the above-mentioned (3), countermeasures such as adding a device to the formulation and applying heat during lamination have been considered, but no satisfactory results have been obtained yet.

Furthermore, various anti-aging agents, ultraviolet absorbers, etc. have been investigated as an improvement measure for the above (4), but these are insufficient in terms of the properties of surface preservation materials.

In any case, the current situation is that sufficient characteristics have not been obtained.

[Problem that the invention seeks to solve]

The object of the present invention is to provide an adhesive composition for surface protection materials that shows a significantly small increase in adhesive strength over time, has a small amount of plasticizer transferred from the object to be protected, and does not leave adhesive residue due to a decrease in cohesive strength over time. The goal is to provide the following.

[Means for solving problems]

The present invention relates to a mixture of A/B/A or A/B/A and A'/B' (wherein A and A5 each represent a block consisting of styrene or a styrene analog, and B and B'' each represent a conjugated diene block. 100 parts by weight of a block co-polymer obtained by hydrogenating a polymerized block consisting of 100 parts by weight of a polymerized block consisting of The present invention relates to an adhesive composition for a surface protection material, comprising 20 to 400 parts by weight of the above-mentioned compound having softening properties of the copolymer (hereinafter also referred to as compound A).

A in A/B/A used in the present invention is styrene or a styrene analog (e.g., vinylstyrene, vinylxylene, ethylstyrene, isopropylstyrene, α
- Alkylated styrene such as methylstyrene) is a polymeric block whose preferred molecular weight is 2
, 000 to about 100.000, and a preferable glass transition temperature is 20°C or higher. Further, B is a polymer block consisting of a conjugated diene, such as butadiene, isoprene, and the like. Its preferred molecular weight is to, ooo to 300. It is about Goo, and
A preferred glass transition temperature is -20°C or lower. Also,
As for the degree of hydrogenation, it is desirable that the conjugated diene block is almost selectively hydrogenated, and it is 60% or more of the diene component of the copolymer, more preferably 80%.
As mentioned above, it is preferable to use hydrogenated products.If the degree of hydrogenation is 60% or less, the affinity for polar objects to be protected increases, the adhesive strength increases, and when laminated to polyvinyl chloride plates, etc. Increased plasticizer migration,
Cohesive failure tends to occur after long-term storage. It is also disadvantageous in terms of weather resistance. The preferred 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 mixed. The definitions of Ao and Bo are the same as those of A and B above, respectively, and the weight ratio of Ao and Bo is A"+B'm5: 95-5
0:50 is preferred.

The pre-hydrogenated Pro7 polymer is prepared by conventional means. For example, a styrene (homogeneous) sliving polymer is prepared using 5aC-butyllithium or the like in a hydrocarbon solvent (e.g., cyclohexane, etc.), and then a conjugated diene is introduced to form a styrene (homogeneous)-conjugated diene polymer. Guiblock is produced, and in addition to this, styrene (a congener)
is added 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 ends of the Gouiblock may be inactivated and used as they are as the Gouiblock.

The method of hydrogenating the conjugated diene polymer thus obtained is to dissolve the polymer in an inert hydrocarbon solution (e.g., cyclohexane, etc.) and add cobalt, 1,000 kels, etc., which has been reduced using a catalyst such as an alkyl aluminum. Add, usually at 25 to 50°C, for example, 5 to 40 kg/
Examples include a method of applying pressure with CD hydrogen and reacting for about 10 to 60 minutes.

The presence or absence of vinyl groups in the products produced by hydrogenation is
For example, it can be easily investigated by infrared analysis.

Since the compound A used in the present invention is used to impart tackiness and as a softening agent to the above-mentioned copolymer, it must be a compound that has these true effects or a compound that has each of these properties. Used in combination.

Note that the material that only provides softening properties is not necessarily essential, and may be added as desired.

Typical compounds A used in the present invention include: (1) petroleum resins whose main components are piperylene, isoprene, etc., and their hydrogenated products; (2) petroleum resins whose main components are styrene, α-methylstyrene, alkylbenzene, etc. Aromatic petroleum resins and their hydrogenated products, ■Terpene resins and modified terpene resins whose main components are α-pinene, β-pinene, etc., and their hydrogenated products, ■Phenolic resins and modified phenolic resins, xylene-based resins Examples include resins, modified xylene resins, and hydrogenated products thereof; (1) rosin resins, modified rosin resins, and hydrogenated products thereof; particularly preferred are styrene, α
Examples include hydrogenated products of aromatic petroleum resins containing methylstyrene, alkylbenzene, etc. as main components, hydrogenated products of terpene resins, and hydrogenated products of modified rosin.

The above-mentioned compounds have a tackifying effect, and among these compounds, those having a softening point of 40° C. or lower can also be used for the purpose of softening the copolymer.

Compound A used for the purpose of softening includes, in addition to the above, liquid rubbers such as polybutene, hydrogenated polybutadiene, and hydrogenated polyisoprene, other naphthenic or aromatic process oils, and dioctyl phthalate. Preferred examples include compounds used as plasticizers such as dioctyl adipate.

The bromine number of these compounds A is 15 or less, preferably 10
It is as follows. When the bromine value of the compound is greater than 15, the affinity for polar protected objects increases, the adhesive strength increases, and
It also has a high affinity with plasticizers, and more plasticizer transfers to the adhesive after lamination, making cohesive failure more likely to occur after long-term storage.

The compounding amount of compound A is A/B/A or A/B/A and A'
/B' in an amount of 20 to 400 parts by weight per 100 parts by weight of the mixture. If the amount is less than 20 parts by weight, the initial adhesion to the object to be protected will be poor, and if it exceeds 400 parts by weight, the affinity to the object to be protected will be too high, and the release will be significantly heavy after long-term storage. Also, heat resistance and weather resistance deteriorate.

20 when compound A is added only for the purpose of tackification.
~200 parts by weight, preferably 30-150 parts by weight are sufficient. Therefore, an amount of 0 to 200 parts by weight, preferably 10 to 150 parts by weight, is sufficient for the compound used for softening purposes.

When the amount of Compound A added for the purpose of tackification exceeds 200 parts by weight, the affinity for the object to be protected increases, and peeling after long-term storage tends to become difficult.

If the amount of Compound A added for the purpose of softening exceeds 200 parts by weight, the adhesive strength tends to increase and the heat resistance and weather resistance tend to deteriorate.

The composition of the present invention may further contain various commonly used materials such as rubbers, resins, softeners, fillers, anti-aging agents, and ultraviolet absorbers, depending on the purpose, to the extent that they do not go against the spirit of the present invention. Good too.

A surface protection material can be prepared by forming the adhesive composition of the present invention as an adhesive layer on a base material.

As the base material for the surface protection material, conventionally known materials are used, such as plastic films (polyethylene, polypropylene, polyvinyl chloride, etc.). These films can be subjected to adhesive treatments (corona, undercoat) and backside treatments as required.

The thickness of each layer of the surface protection material is preferably as follows. That is, the adhesive layer preferably has 200 P or less, more preferably 5 to 50 P, and the base material layer has 300 P or less,
Preferably it is 10-100P.

The surface protection material can be easily produced, for example, by dissolving an adhesive composition in an organic solvent and applying the solution onto a substrate by a conventional method. It can also be easily produced by melt coextrusion of a polyolefin resin or the like and the adhesive composition.

[Action/Effect]

The adhesive composition of the present invention has a very small effect of increasing the adhesive strength orally, the amount of plasticizer transferred from the object to be protected is small, and there is no adhesive residue due to a decrease in cohesive strength over time, so there is no initial adhesive strength. This has the effect of providing a surface protective material that has excellent adhesive strength and is easy to peel off over time.

Example 1 60. An adhesive having a composition shown in Table 1 and having a solid content of 30% using toluene as a solvent was applied to the treated surface of the polyethylene film and dried at 100° C. for 5 minutes. A tape with an adhesive layer of 10P thickness was made. The details of each component shown in Table 1 are shown in Tables 2 and 3 (the same applies hereinafter).

(Preparation of Polymer 1) 40 g of Methi 1 F and 400 g of cyclohexane were placed in an autoclave, and the autoclave was sufficiently purged with nitrogen.

■ 0.0% sec-butyllithium dissolved in cyclohexane.
003 mole is added.

React at 060°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 40g of cyclohexane.
0g was added to the reaction system and reacted at 60°C for 1 hour.

SBS Profuku 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°C of cyclohexane at 25°C for 10 minutes, and the mixture was added to the reaction system (2).

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

(2) Table 1 shows the results of analyzing the finished polymer.

Example 2 One side of a 25Pga polyester film was treated with silicone, and a 20P thick adhesive layer was formed on the untreated side using the same method as in Example 1.

Polymer 2 was prepared according to Polymer 1.

Example 3 The blended composition shown in Table 1 was kneaded and polyethylene [
Density 0.925. Ml (melt index) -6
, 0) to form a 40P polyethylene film with 157. A tape with a thick adhesive layer was prepared.

Polymer 3 was prepared according to Polymer 1.

Comparative examples 1 to 3 A tape was made in the same manner as in Example 1.

Polymer 4 was prepared according to Polymer 1.

Experimental Example 1 The initial adhesive strength and adhesive strength after aging of the samples obtained in the above Examples and Comparative Examples were investigated, and the results are shown in Table 1.

〔Test method〕

Adhesive crab polyvinyl chloride board (Ra-2,0μ), matte acrylic board (Ra-1,2μ) and melamine board (R
a=0.8. Samples were laminated to u) under the conditions of 20°C ± 65RH, and the 180°C peel adhesion strength was measured after 20 minutes (initial stage), 40°C x 3 months, and 50°C x 1 month. The peeling speed is 300 per minute.

Procedural amendment cap button July C day, 1985

Claims (1)

Scope of Claims: (a) A/B/A or a mixture of A/B/A and A'/B' (wherein A and A' each represent a polymer block consisting of styrene or a styrene analog; 100 parts by weight of a block copolymer obtained by hydrogenating (B' and B' each represent a polymer block consisting of a conjugated diene) (b) having an aliphatic double bond, and its JISK2421
An adhesive composition for a surface protection material, characterized in that it has a bromine value of 15 or less, and comprises 20 to 400 parts by weight of a compound having tackifying properties and/or softening properties of the copolymer described above.