JPS6270475A - Self-adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the titled compsn. having excellent low-temp. initial bond strength, high-temp. holding power, peeling resistance, and adaptability to die cutting, by incorporating a particular copolymer mixture, a tackifier and a softening agent. CONSTITUTION:5-40wt% vinyl arom. compd. (a) is copolymerized with a conjugated diene compd. (b), if necessary, followed by termination with an iso(thio) cyanate compd. (c), thereby obtaining a linera chain block copolymer (A) having a weight-average MW of 70,000-500,000. 3-50wt% component (a) is copolymerized with the components (b), if necessary, followed by termination with the component (c), thereby obtaining a linear chain block copolymer (B) having a weight-average MW of 3,000-50,000. 100pts.wt. copolymer mixture comprising 90-50wt% component A and 10-50wt% component B is blended with 20-200pts.wt. tackifier and 0-100pts.wt. softening agent to obtain a self-adhesive compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a vinyl aromatic compound with improved adhesive properties.
Regarding a new adhesive composition containing a conjugated diene compound block copolymer as a main component, more specifically, two types of vinyl aromatic compound-conjugated diene compound block copolymers having specific structures having different molecular weights are used in a specific manner. The present invention relates to a novel hot-melt pressure-sensitive adhesive composition containing a mixture as a main component.

[Conventional technology]

Conventionally, as a hot melt adhesive, for example,
Publication No. 6-50758 or JP-A-53-10293
The one described in Publication No. 8 is known.

In recent years, in the field of hot-melt adhesives, there has been an increasing demand for adhesives with excellent properties that combine low-temperature initial adhesion and high-temperature retention.

[Problem that the invention seeks to solve]

However, the above-mentioned conventional pressure-sensitive adhesives do not simultaneously satisfy all of the important properties required for the pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet, such as low-temperature initial adhesive strength and high-temperature holding power.

The present invention was made against the background of the above-mentioned conventional technical problems, and an object of the present invention is to provide an adhesive having both low-temperature initial adhesive strength and high-temperature retention strength.

[Means for solving problems]

That is, the present invention is obtained from (a) a vinyl aromatic compound and a conjugated diene compound, and has a weight average molecular weight of 70.000 to 70.000.
500,000 and a vinyl aromatic compound component content of 5 to 40% by weight, optionally a linear block copolymer A terminal-terminated with an isocyanate compound or an isothiocyanate compound. , an isocyanate compound or isothiocyanate compound obtained from a vinyl aromatic compound and a conjugated diene compound, having a weight average molecular weight of 3.000 to 50,000, and containing a vinyl aromatic compound component of 3 to 50% by weight. Linear block copolymer B end-grouped with an oceanate compound, by weight 9
100 parts by weight of a copolymer mixture in a ratio of 0 to 50:10 to 50, (b) 20 to 200 parts by weight of a tackifier, and (c)
The present invention provides a pressure-sensitive adhesive composition containing 0 to 100 parts by weight of a softener.

The copolymer mixture (a) in the present invention is a mixture of the block copolymer A and block copolymer B described above.

Here, the block copolymer A is a linear chain obtained by copolymerizing a vinyl aromatic compound and a conjugated diene compound, or further terminal-grouping with an isocyanate compound or an isothiocyanate compound as necessary. A block copolymer having a weight average molecular weight of 70.
000 to 500,000, preferably 100,000 to
300.000, and the content of the vinyl aromatic compound component is 5 to 40% by weight, preferably 10 to 30% by weight.

The weight average molecular weight of block copolymer A is 70.000
If it is less than that, the high temperature holding power of the composition of the present invention will be insufficient;
On the other hand, if it exceeds 50.0.000, the low temperature initial adhesive strength of the composition of the present invention will be insufficient. In addition, block copolymer A
The content of vinyl aromatic compound component in is 5% by weight.
If it is less than that, the high temperature holding power of the composition of the present invention will be insufficient;
On the other hand, if it exceeds 40% by weight, the low temperature initial adhesive strength of the composition of the present invention will be insufficient.

Furthermore, by end-grouping the block copolymer A with an isocyanate compound or an isothiocyanate compound, it is expected that the high temperature holding power of the resulting composition will be improved.

On the other hand, block copolymer B is a linear block copolymer obtained by copolymerizing a vinyl aromatic compound and a conjugated diene compound, and further adding terminal groups with an isocyanate compound or an isothiocyanate compound. and the weight average molecular weight is 3,000 to 50,000, preferably 5.000 to 40,000, and the content of the vinyl aromatic compound component is 3 to 50% by weight,
Preferably it is 5 to 30%.

If the weight average molecular weight of block copolymer B exceeds 50,000, the low temperature initial adhesive strength of the composition of the present invention will be insufficient, while if it is less than 3,000, the die cutability of the composition of the present invention will be poor. . Furthermore, if the content of the vinyl aromatic compound component in block copolymer B is less than 3% by weight, the high temperature holding power will be insufficient, while if it exceeds 50% by weight, the low temperature initial adhesive strength of the composition of the present invention will be insufficient. becomes.

Furthermore, it is necessary for block copolymer B to have its molecular chain terminal end-grouped with an isocyanate compound or isothiocyanate compound, and if such end-grouping is not performed, the resultant composition Low-temperature adhesive strength becomes inferior.

The mixing ratio of block copolymer A and block copolymer B is 90-50:10-50, preferably 85-60:15-40.

If the proportion of block copolymer A exceeds 90% by weight, the low temperature initial adhesive strength of the composition of the present invention will be insufficient;
If it is less than %, the high temperature retention ability of the composition of the present invention will be insufficient.

The block copolymer A is a block bond type represented by any of the following general formula (1) S-1-3 general formula (2) 5-1 general formula (3) l-3-1, or Furthermore, it is terminated with an isocyanate compound or an isothiocyanate compound.

Here, S is a polymer block of vinyl aromatic compound, ■
represents a polymer block of a conjugated diene compound. and,
Particularly preferred are those represented by general formula (1) or general formula (2).

Block copolymer A represented by general formula (1) can be produced, for example, as follows.

That is, an ether or a tertiary amine is added to a hydrocarbon solvent as necessary, and a vinyl aromatic compound is first polymerized using an organic lithium compound as a polymerization initiator. After this polymerization reaction is substantially completed, a conjugated diene compound is added and polymerized, and after this polymerization reaction is substantially completed, a vinyl compound is added and polymerized sequentially. Furthermore, an isocyanate compound or isothiocyanate compound may be added in an amount of 1 to 20 times the mole of the organolithium initiator to form a terminal group.

In addition, as another method for producing the block copolymer A represented by the general formula (1), for example, an ether or a tertiary amine is added to a hydrocarbon solvent as needed, and an organic lithium compound is started to polymerize. First, a vinyl aromatic compound is polymerized, and after this polymerization reaction is substantially completed,
It can also be produced by adding a conjugated diene compound for polymerization and then adding a camping agent.

Next, the block copolymer B is represented by any of the following general formula (4) 5i-Y general formula (5) S-1-3-Y general formula (6) l-5-T-Y It is represented by the block join type.

Here, S and I are blocks according to the above definitions, and Y is an isocyanate compound or an isocyanate compound. The block copolymer B is preferably one represented by general formula (5) or general formula (6).

The method for producing this block copolymer B uses a method similar to the method shown for the block copolymer A above.

The vinyl aromatic compounds for the above block copolymer A or block copolymer B include styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, 0-methylstyrene, p-tert-butyl Styrene, dimethylstyrene, vinylnaphthalene, etc. can be used. Among these, styrene is preferred.

Further, as the conjugated diene compound, butadiene, isoprene, piperylene, etc. can be used. Among these, isoprene is preferred.

Furthermore, the isocyanate compounds used in the production of copolymer B or, if necessary, copolymer A include, for example, phenyl isocyanate, 0-9m + p-chlorophenylisocyanate, methyl isocyanate,
Ethyl isocyanate, n-propylisocyanate,
Examples include n-butyl isocyanate, octadecyl isocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and the like.

Furthermore, copolymer B or, if necessary, copolymer A
Examples of the isothiocyanate compounds used in the production of include phenylisothiocyanate, o-, m-
-, p-chlorophenylisothiocyanate, methylisothiocyanate, ethylisothiocyanate, n-propylisothiocyanate, n-butylisothiocyanate, octadecylisothiocyanate, tolylene diisothiocyanate, hexatyldisothiocyanate, Examples include isothiocyanate.

On the other hand, as a polymerization method for producing the block copolymer A or B, either an isothermal polymerization method or an adiabatic polymerization method can be used.

Moreover, the polymerization temperature range at this time is 30 to 120°C.

Further, examples of the hydrocarbon solvent used in the production of block copolymer A or B include cyclobencune, cyclohexane, benzene, ethylhensen, xylene, and mixed solvents of these with pentane, hexane, heptane, butane, etc. I can do it.

Furthermore, examples of the ether or tertiary amine added to the hydrocarbon solvent as necessary include tetrahydrofuran, diethyl ether, anisole, dimethoxyhensen, ethylene glycol, dimethyl ether,
Ether compounds and tertiary amine compounds such as triethylamine, N-dimethylaniline, and pyridine are used.

Furthermore, the block copolymer A or B may be hydrogen-converted at an appropriate ratio as necessary.

Furthermore, examples of organic lithium compounds used as polymerization initiators include n-butyllithium 11.5eC-butyllithium, tert-butyllithium, n=hexyllithium, 15O-hexyllithium, phenyllithium, naphthyllithium, and the like. is used.

Furthermore, examples of the coupling agent used in other production methods for producing block copolymers include dichlorosilane, monomethyldichlorosilane, dimethyldichlorosilane, monoethyldichlorotin, monobutyldichlorosilane, dichlorotin, monomethyldichloro Tin, monoethyldichlorotin, dibutyldibromtin, etc. are used.

A copolymer mixture (a) obtained by mixing block copolymers A and B as described above is blended with an adhesive agent (b).

Such tackifiers (b) include rosin resins, polyterpene resins, synthetic polyterpene resins, alicyclic hydrocarbon resins, coumaron resins, phenolic resins, terpene-phenolic resins, and aromatic hydrocarbons. Resin, aliphatic hydrocarbon resin, etc. are used. Among these, rosin resins, polyterpene resins, and alicyclic hydrocarbon resins are particularly preferred. These tackifiers (b) can be used alone or in combination of two or more.

The blending amount of the tackifier (b) is the same as that of the copolymer mixture (
b) 20 to 200 parts by weight, preferably 50 to 150 parts by weight per 100 parts by weight.

If the amount of this tackifier (b) is outside the above range,
Appropriate low-temperature initial adhesion and high-temperature holding power may not be sufficient.

The adhesive composition of the present invention may further contain a softener (c), and the softener (c) may include naphthenic, paraffinic, or aromatic process oil alone or in combination. A mixture of more than one species can be used.

The blending amount of the softener (c) is 100% of the copolymer mixture (a).
0 to 100 parts by weight, preferably 20 to 7 parts by weight
It is 0 parts by weight. Arrangement 3 of Softener (C) If the content exceeds 100 parts by weight, the softener will ooze out onto the adhesive surface over time, causing undesirable effects.

In addition to the above, the adhesive composition of the present invention may optionally contain stabilizers such as antioxidants and ultraviolet absorbers, and inorganic substances such as calcium carbonate, talc, clay, titanium oxide, silica, magnesium carbonate, and carbon black. Fillers, colorants, etc. may also be added.

The components of the adhesive composition described above are mixed in a general tank mixer, closed kneader, or the like under heating and, if necessary, in a nitrogen gas atmosphere.

The pressure-sensitive adhesive composition of the present invention has the greatest economical effect when it is heated and mixed and directly applied to form a pressure-sensitive adhesive layer.

However, it is also possible to apply a mixture using a conventional solvent or to form an emulsion.

The adhesive composition of the present invention obtained in this way forms an adhesive layer when applied to a base material, so it can be used for various adhesive tapes, labels, adhesives for fixing various lightweight plastic molded products, and backings for fixing car vents. It is effective as a glue, etc., and is also effective as an adhesive layer-forming material for frozen foods, adhesive tapes used in cold regions, and Rahel.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the scope of the present invention is not limited by these.

In addition, in the examples, parts and % are, in principle, based on weight.

Reference Example: Fission value of μwc copolymer A (1) In a washed and dried autoclave with a stirrer and a jacket, cyclohexane and n-pentane were mixed at 9:1.
1 (weight ratio) mixture 85.000
After adding 0.12 g of tetrahydrofuran to g, the internal temperature was brought to 60°C.

Next, a hexane solution containing 0.5 g of n-butyllithium was added, and then 120 g of styrene was added and polymerized for 60 minutes. The polymerization conversion rate of styrene here is 10
It was 0%.

Then, 700 g of isoprene was added and polymerized for -060 minutes. The polymerization conversion rate of isoprene here is 100%
Met.

Finally, 120 g of styrene was added and polymerized for 60 minutes.

The polymerization conversion rate of styrene here was also 100%.

During each of the following polymerization reactions, the temperature of the system was maintained at 60°C.

After the final polymerization process, 2.6-
C-tert-butyl-p-cresol was added, and then the mixture of cyclohexane and n-pentane was removed by heating to obtain a block copolymer AI.

Further, block copolymer A2 was produced in the same manner as A1 except that the amount of monomers was changed.

(2) Next, a block copolymer A3 terminal-grouped with an isocyanate compound was produced by the following operation.

That is, using the same equipment as in the production of block copolymer AI, 120 g of styrene and 700 g of isoprene were prepared in the same manner.
g, and further 120 g of styrene were sequentially polymerized.

Then, a tetrahydrofuran solution containing 1.86 g of phenyl isocyanate was added, and 2.6-sheet te
After adding rt-butyl-p-cresol, the solvent was removed by heating to obtain block copolymer A3.

(3) Next, using the same equipment as in the production of block copolymer A1, 120 g of styrene and 450 g of isoprene were sequentially polymerized in the same manner, and then a cyclohexane solution containing 0.9 g of monomethyldichlorosilane was added, Further 2.
After adding 6-tert-butyl'-p-cresol, the solvent was removed by heating to obtain block copolymer A4.

(4) Next, block copolymer A5 was produced using the same equipment as in the production of block copolymer A3, except that 2.15 g of phenyl isothiocyanate was used instead of phenyl isocyanate. I got it.

(5) Next, using the same equipment as in the production of block copolymers AI except for changing the amount of monomers, and performing the same operations, block copolymers a1 to a1 for comparison as shown in Table 1 were produced.
A4 was manufactured.

1 Preparation of Polymer B (1) In a washed and dried autoclave equipped with a stirrer and a jacket, add cyclohexane and n-pentane at 9=
After adding 0.02 g of tetrahydrofuran to 500 g of a mixed liquid obtained by mixing at a ratio of 1 (weight ratio), the internal temperature was set to 60°C.

Next, a hexane solution containing 0.5 g of n-butyllithium was added, and then 12 g of styrene was added and polymerized for 60 minutes. The polymerization conversion rate of styrene here is 100
%Met.

Then, 70 g of isoprene was added and polymerized for 60 minutes. The polymerization conversion rate of isoprene here was 100%.

A tetrahydrofuran solution containing 1.86 g of phenyl isocyanate was then added.

During each of the above polymerization reactions, the temperature of the system was maintained at 60-7°C. After the final polymerization process, 2,
Add 6-tert-butyl-p~cresol;
Thereafter, the mixed solution of cyclohexane and n-pentane was removed by heating to obtain block copolymer B1.

In addition, a comparative block copolymer b1 was produced in the same manner as above except that phenyl isocyanate was not added.

(2) In a washed and dried autoclave with a stirrer and a jacket, add cyclohexane and n-pentane in 9 parts.
1 (weight ratio) mixed liquid 5,000
After adding 0.12 g of tetrahydrofuran to g, the internal temperature was brought to 50°C.

Next, a hexane solution containing 0.5 g of n-butyllithium was added, and then 30 g of styrene was added and polymerized for 60 minutes. The polymerization conversion rate of styrene here is 100
%Met.

Next, 240 g of isoprene was added and polymerized for 60 minutes. The polymerization conversion rate of isoprene here was 100%.

Furthermore, 30 g of styrene was added and polymerized for 60 minutes. The addition rate of styrene was 100%.

Next, 2.65 g of hexamethylene diisocyanate
A solution containing tetrahydrofuran was added.

During each of the above polymerization reactions, the temperature of the system was maintained at 60 to 70°C. After the final polymerization process, 2,
Add 6-tert-butyl-p-cresol;
Thereafter, the mixed solution of cyclohexane and n-pentane was removed by heating to obtain block copolymer B2.

In addition, a comparative block copolymer b2 was produced in the same manner as above except that hexamethylene diisocyanate was not added.

(3) A comparative block copolymer was produced in the same manner using the same equipment as in B2 production above, except that 60 g of styrene, 660 g of isoprene, and 60 g of styrene were sequentially polymerized, and then 2.65 g of hexamethylene diisocyanate was added. b
3 was manufactured.

Next, block copolymers b4 to b6 for comparison shown in Table 1 were produced using the same equipment as in producing block copolymer b3 and in the same manner, except that the amount of monomer was changed.

Details of the block copolymer obtained as described above are shown in Table 1.

(Leaving space below) Table 1 Y; phenyl isocyanate terminal group Y'; hexamethylene diisocyanate terminal group Y''; isothiocyanate terminal group Examples 1 to 5 and Comparative Examples 1 to 17 The compositions shown in Table 2 were By placing each of the formulations in a mixing tank heated to 160°C and stirring and mixing for 60 minutes,
A pressure-sensitive adhesive composition having uniform and smooth fluidity was obtained.

Each of these pressure-sensitive adhesive compositions is taken out in a molten state and applied to a base material made of polyester film with an applicator to a thickness of 3.
An adhesive tape sample was prepared by coating to a thickness of 0 microns.

For each of the adhesive tape samples, low-temperature initial adhesive strength, peel strength, high-temperature retention strength, and die-cutting properties were measured.

The results are shown in Table 2.

In addition, various measurements were based on the following methods.

The low-temperature initial adhesion strength was determined by the tilted ball tank measurement method (tilt angle: 306, measurement temperature: 5° C.).

Peel strength is based on JIS Z 1522 (1
806 constant speed peel strength test, measurement temperature 25°C).

The high temperature holding power was based on JIS Z1524.

However, the pasting area was 110 x 10, and the time taken for a 1 kg weight to fall was measured (measurement temperature 45
℃).

The quality of die cutting was judged by the method shown below. That is, a high-quality paper is hot-melt coated with an adhesive composition to a thickness of a predetermined temperature, and after bonding this to a release paper, it is cut into a size of 20caI x 4cI11. Next, with a punching blade of size 1.5cm x 1.5aI+, 2 rows of 10 pieces each were cut so that only the high-quality paper was cut.
Punch out a total of 20 small pieces, and then remove the excess from the release paper by hand. - If the number of adhesive labels peeled off is 0 to 1, mark ○; if 2 to 3, mark Δ; When there were four or more sheets, an x mark was added to judge the quality of the die-cutting properties.

(The following is a blank space) [Effects of the Invention] The adhesive composition of the present invention can provide an adhesive with excellent low-temperature initial adhesion strength and high-temperature holding power. In some cases, adhesive tapes or labels with excellent low-temperature initial adhesion strength, high-temperature retention strength, peel strength, and grip-cutting properties can be obtained.

Claims (1)

[Claims] (1) (A) Obtained from a vinyl aromatic compound and a conjugated diene compound, with a weight average molecular weight of 70,000 to 500,
000, and the content ratio of the vinyl aromatic compound component is 5
~40% by weight of a linear block copolymer A optionally terminated with an isocyanate compound or an isothiocyanate compound, a vinyl aromatic compound and a conjugated diene compound, and the weight average The molecular weight is 3,
000 to 50,000 and a vinyl aromatic compound component content of 3 to 50% by weight, a linear block copolymer B terminal-terminated with an isocyanate compound or an isothiocyanate compound, 90-50 in weight
: Copolymer mixture 10 in a ratio of 10 to 50
0 parts by weight, (b) 20 to 200 parts by weight of tackifier, and (c)
An adhesive composition comprising 0 to 100 parts by weight of a softener.