JPH05302071A - Hot-melt self-adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the title compsn. excellent in the balance between self-adhesive power and holding power. CONSTITUTION:The title compsn. is prepd. by compounding 5-500 pts.wt. tackifying resin with 100 pts.wt. hydrogenated block copolymer having a number- average mol.wt. of 40, 000-280, 000 and prepd. by hydrogenating a block copolymer which comprises 5-40wt.% vinylarom. compd. polymer block contg. at least 90wt.% vinylarom. compd. units, 90-20wt.% conjugated diene polymer block contg. at least 20% 1,2-vinyl bonds, and 5-40wt.% polybutadiene block contg. up to 20% 1, 2-vinyl bonds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-melt type pressure-sensitive adhesive excellent in tackiness performance, stability over time and workability.

[0002]

2. Description of the Related Art Hot-melt type adhesives have the advantages of being non-polluting, saving resources and speeding up production, as compared with conventional solvent-type adhesives and emulsion-type adhesives, and have economical advantages. large. At present, hot-melt adhesives are represented by general formulas (AB) _n A, (BA) _n , (AB) _{n + 1} X.
(Wherein A is a vinyl aromatic compound polymer block, B is a conjugated diene polymer block, X is a coupling agent residue, n
Is an integer of 1 or more. The hydrogenated block polymer obtained by hydrogenating a part or all of the olefinic double bond of the thermoplastic elastomer represented by the formula (1) is used. These are excellent in heat aging resistance and weather resistance as compared with the conventional unhydrogenated block polymer, but have poor balance of adhesive strength and holding power, and further improvement is desired.

[0003]

DISCLOSURE OF THE INVENTION As a result of intensive investigations aimed at improving the above-mentioned drawbacks, the present inventors have found that the use of a hydrogenated block copolymer having a specific structure as the main material of the pressure-sensitive adhesive makes it It was found that a pressure-sensitive adhesive composition having an excellent balance of holding power and the holding power was obtained, and the present invention was completed.

That is, according to the present invention, (a) vinyl aromatic compound polymer block (A) containing 90% by weight or more of vinyl aromatic compound (hereinafter referred to as "block A") 5 to 40% by weight, 1,2 vinyl Conjugated diene polymer block (B) having 20% or more bonds (hereinafter referred to as "block B") 90
A number average molecular weight obtained by hydrogenating a block copolymer composed of 5 to 40% by weight of a polybutadiene polymer block (C) (hereinafter referred to as "block C") containing 20% by weight and 20% or less of 1,2 vinyl bonds. Hot containing (b) 5 to 500 parts by weight of tackifying resin per 100 parts by weight of 40,000 to 280,000 hydrogenated block copolymer (hereinafter referred to as "hydrogenated block copolymer (a)"). The present invention provides a melt-type pressure-sensitive adhesive composition.

In the hydrogenated block copolymer used in the present invention, the proportion of the block (A) is 5 to 40% by weight, preferably 5 to 30% by weight, particularly preferably 10 to 30% by weight. is there. If the amount of the block (A) is less than 5% by weight, the holding power will decrease, and if it exceeds 40% by weight, the tackiness will decrease. In the hydrogenated block copolymer used in the present invention, the proportion of the block (B) is 90 to 20% by weight.
And preferably 90 to 40% by weight, particularly preferably 80 to 40% by weight. 20% by weight of block (B)
If it is less than 90% by weight, the adhesive force is lowered, and if it exceeds 90% by weight, the holding force of the obtained adhesive composition is lowered. The 1,2-vinyl bond content in the block (B) is 20% or more, preferably 30% or more, and particularly preferably 40% or more.
When the 1,2-vinyl bond is less than 20%, the tackiness of the composition is lowered. In the hydrogenated block copolymer used in the present invention, the proportion of the block (C) is 5 to 40% by weight, preferably 5 to 30% by weight, particularly preferably 10 to 30% by weight. If the amount of the block (C) is less than 5% by weight, the holding power will be lowered, and if it exceeds 40% by weight, the adhesive force of the composition will be lowered. In addition, 1, 2 in block (C)
When the vinyl bond content exceeds 20%, the holding power of the composition is lowered.

The hydrogenated block copolymer (a) used in the present invention can be produced by the following method. That is, block (C), block (B), block (A)
In this order, living anion polymerization is performed in an organic solvent, and the block copolymer is hydrogenated. Specifically, for example, an organolithium compound such as sec-butyllithium is used as an initiator, and an organic solvent such as benzene or cyclohexane is used as a polymerization solvent in the first stage under vacuum or under a high-purity nitrogen stream.
-By polymerizing butadiene, a low vinyl polybutadiene block to be the block (C) is polymerized. Then, a microstructure modifier such as tetrahydrofuran or diethyl ether and 1,3-butadiene for the second stage are added to polymerize the high vinyl polybutadiene block to be the block (B). After the second stage polymerization,
Further, subsequently, a vinyl aromatic compound is added and the block (A) is polymerized to obtain a block copolymer composed of (C)-(B)-(A) in this order.

At the end of the first stage, an appropriate amount of the polymerization solution is sampled and measured by gel permeation chromatography (GPC) to obtain the molecular weight of block (C). Similarly, the molecular weight of the block (B) of the second stage is obtained by subtracting the molecular weight value of the first stage from the molecular weight value obtained by GPC measurement of the sample at the end of the second stage. The molecular weight of the block (A) in the third stage is the GPC of the sample in which the polymerization is completed.
It can be determined by subtracting the molecular weight values of the first step and the second step from the molecular weight values obtained by the measurement. The hydrogenated block copolymer of the present invention is prepared by dissolving the block copolymer thus obtained in an inert solvent,
It can be obtained by hydrogenation in the presence of a hydrogenation catalyst under pressurized hydrogen at 150 ° C and 1 to 100 kg / cm ² .
At this time, the hydrogenation rate of the olefinic unsaturated bond is preferably 90% or more. As the vinyl aromatic compound constituting the block (A) of the hydrogenated block copolymer (a) of the present invention, styrene, α-methylstyrene, vinyl ketone, p-tert-butylstyrene and the like are preferable, and styrene and the like are preferable. Examples of the conjugated diene forming the block (B) include butadiene and isoprene. The molecular weight of the hydrogenated block copolymer (a) used in the present invention is 40,000 to 280,000, preferably 40,000 to 200,000, and more preferably 40,000 to 160,000. Molecular weight less than 40,000 and 2
If it exceeds 80,000, the retention rate will be poor.

The tackifying resin used in the present invention includes rosin resins, polyterpene resins, synthetic polyterpene resins, alicyclic hydrocarbon resins, coumarone resins,
Phenolic resins, terpene-phenolic resins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins, etc., preferably rosin resins, polyterpene resins, alicyclic hydrocarbon resins and the like can be mentioned. These tackifier resins may be used alone or in admixture of two or more. In the present invention, the amount of the tackifying resin used is 5 to 500 parts by weight, preferably 20 to 300 parts by weight, particularly preferably 50 to 200 parts by weight, based on 100 parts by weight of the hydrogenated block copolymer (a). is there. If the tackifying resin is out of this range, the balance of the tackiness and the retention rate of the obtained composition is poor, and the object of the present invention cannot be achieved.

The pressure-sensitive adhesive composition of the present invention contains two components, the hydrogenated block copolymer (a) and the tackifying resin as essential components, but a softener may be added in addition to these components. Examples of the softening agent include naphthene-based process oil, paraffin-based process oil, and various liquid rubbers such as liquid polyisoprene rubber and liquid polyacrylate.
Liquid polybutene, liquid polyisoprene isobutylene rubber, liquid acrylic rubber, liquid polybutadiene rubber and the like can be used. These softening agents may be used alone or in admixture of two or more. The amount of the softening agent used is preferably 100 with respect to 100 parts by weight of the hydrogenated block copolymer.
It is less than or equal to parts by weight. Further, in the pressure-sensitive adhesive composition of the present invention, if necessary, other than the above, an antioxidant, a stabilizer such as an ultraviolet absorber, calcium carbonate, silica, talc, clay, mica, whiskers titanate, zinc oxide, titanium oxide, Inorganic fillers such as magnesium carbonate and carbon black,
You may add a coloring agent, a pigment, etc. Furthermore, the pressure-sensitive adhesive composition of the present invention may contain other elastomers such as natural rubber, polyisoprene rubber, polybutadiene rubber, SBR, high styrene rubber, chloroprene rubber, EPT, EPR as long as the properties of the hot-melt pressure-sensitive adhesive are not lost. , Acrylic rubber, polyisoprene isobutylene rubber, polypentenamer rubber and the like, and thermoplastic resins such as 1,2 polybutadiene, polybutene-1, polyethylene, EVA,
EVA modified polymer, ethylene-ethyl acrylate copolymer, isotactic polypropylene, polyphenylene ether, ionomer, ethylene copolymer, polystyrene, styrene-acrylonitrile copolymer, styrene resin such as HIPS, ABS, AES, MBS You may mix 1 type (s) or 2 or more types.

These components can be mixed in a general tank mixer, a closed kneader, etc. under heating and under a nitrogen gas atmosphere if necessary. The pressure-sensitive adhesive composition of the present invention has the greatest economic effect when mixed and applied by the hot melt method. However, it is also possible to mix and apply by a normal solution type or emulsion type.
The hot-melt pressure-sensitive adhesive composition of the present invention thus obtained is used for various adhesive tapes / labels, pressure-sensitive thin plates, back glue for fixing various lightweight plastic molded products, back glue for fixing carpet, glue for fixing tile, etc. It is particularly effective for adhesive tapes and labels.

[0011]

EXAMPLES The present invention will be described in more detail below with reference to examples. The examples are representative of the invention,
It does not limit the scope of the invention. Examples 1 to 7 and Comparative Examples 1 to 11 Hydrogenated block copolymers shown in Tables 1 and 2 and an alicyclic hydrocarbon resin as a tackifier (Alcon P-9
No. 0, manufactured by Arakawa Chemical Co., Ltd.) and PW-90 (manufactured by Idemitsu Petroleum Co., Ltd.) as a softening agent were mixed at a blending ratio shown in the same table using a Labo Plastomill (manufactured by Toyo Seiki) at 180 ° C. and 70 rpm for 20 minutes. Toluene / methylene chloride = 1
It is dissolved in a mixed solvent consisting of 1/1 (weight ratio) to give a viscosity of 1,
It was adjusted to about 000 to 3,000 cP. Next, each composition was applied on a polyester film so as to have a thickness of 35 μm, and dried in a gear oven at 120 ° C. for 20 minutes to obtain a test tape. The obtained test tape was conditioned at 23 ° C. for 24 hours, and then the performance of the pressure-sensitive adhesive was evaluated using the evaluation methods shown below.

Adhesion Evaluation Method Under a 23 ° C. environment, a steel ball having a diameter of 14/32 inches is rolled from a position 15 cm from the bottom of a slope of 21.5 °, and a distance to stop on a test tape stuck on a flat surface is obtained. It was This operation was repeated 5 times for each test tape, and the average value was used as the evaluation of tackiness. ⊚: Stopping distance is 0 cm to 5 cm ○: Stopping distance is 5 cm to 15 cm △: Stopping distance is 15 cm to 25 cm ×: Stopping distance is 25 cm or more Holding power evaluation method A test tape is cut into a width of 1.5 cm, and water-resistant abrasive paper # 2 is used.
1. Stainless steel plate (SUS304) polished by 80
It was pasted with a length of 5 cm and pressure-bonded with a 2 kg rubber roll. Under a 23 ° C. environment, a 1 kg load was hung vertically on the end of the test tape, and the time until the test tape dropped was measured. This operation was repeated 3 times for each test tape, and the average value was evaluated. ◯: Falling time is 70 minutes or more Δ: Falling time is 40 minutes to 70 minutes ×: Falling time is 40 minutes or less The results are shown in Tables 1 and 2.

[0013]

[Table 1]

[0014]

[Table 2]

From the results of Examples 1 to 7 shown in Table 1, it can be seen that the pressure-sensitive adhesive composition of the present invention is superior in the balance of adhesive force and holding force as compared with Comparative Examples 1 to 11 shown in Table 2. In Comparative Example 1, the main material is ABA (A: polystyrene,
B: Polybutadiene) type thermoplastic elastomer, which is hydrogenated and has poor holding power. Comparative Examples 2 to 9
Since the hydrogenated block copolymer is outside the scope of the present invention, the balance between adhesiveness and holding power is poor. Comparative Examples 10-1
In No. 1, the compounding ratio is out of the range of the present invention, so that the balance between adhesiveness and holding power is poor.

[0016]

INDUSTRIAL APPLICABILITY According to the present invention, a hydrogenated block copolymer having a specific structure is used as a main component of a pressure-sensitive adhesive to obtain a pressure-sensitive adhesive composition having an excellent balance of tackiness and holding power. It has been found and has great industrial value.

Claims (1)

[Claims] 1. A vinyl aromatic compound polymer block (A) 5 to 40 containing (a) 90% by weight or more of a vinyl aromatic compound.
% By weight, 90 to 20% by weight of conjugated diene polymer block (B) having 20% or more 1,2 vinyl bonds and 5 to 40% by weight of polybutadiene polymer block (C) having 20% or less 1,2 vinyl bonds. Of (b) tackifying resin to 100 parts by weight of a hydrogenated block copolymer having a number average molecular weight of 40,000 to 280,000 obtained by hydrogenating the block copolymer
A hot-melt pressure-sensitive adhesive composition containing about 500 parts by weight.