JPS6142582A - Hot-melt adhesive composition - Google Patents

Abstract

PURPOSE:The titled composition having excellent initial tack strength, peeling strength, die cuttability, and persistence, consisting of a specified block copolymer, a tackifier, and a softening agent. CONSTITUTION:20-200pts.wt. tackifier (e.g. rosin resin), and 0-100pts.wt. softening agent (e.g. naphthenic process oil) are incorporated into 100pts.wt. vinyl aromatic compound-conjugated diene block copolymer which contains 5-70wt% total bound vinyl aromatic compound, has a weight-average molecular weight of 10,000-500,000, is shown by formula I {where A is a vinyl aromatic compound polymer block; B is a copolymer of a vinyl aromatic compound and a conjugated diene in a weight ratio of 0-50:100-50 and has 0-10 tapered blocks with an increasing number of vinyl aromatic compound units; Y is shown by formula II[where R1 and R2 each are H or a CnH2n+1; (n) is 1-20; X is a halogen; M is Si or Sn]}, and is obtained in a hydrocarbon solvent using an organic Li compound as an initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure-sensitive adhesive composition, particularly a pressure-sensitive adhesive composition suitable as a hot-melt pressure-sensitive adhesive.

Generally, adhesives are used to form the adhesive layer of adhesive tapes such as craft tapes, labels, and other adhesive sheets. It is desired that such an adhesive has appropriate fluidity when melted by heat, and therefore can be applied directly to a substrate to form an adhesive layer without using an organic solvent. Conventionally, such hot bath melt adhesives include 6, for example,
The adhesives described in Japanese Patent Application Laid-open No. 56426 and Japanese Patent Application Laid-open No. 54-33536 are known, but these conventional adhesives have initial adhesive strength, which is an important property required for the adhesive layer of an adhesive sheet. It is not possible to simultaneously satisfy all of the above requirements, such as holding power and holding power.

As a result of intensive research based on the above-mentioned circumstances, the present invention has been developed by using a block copolymer with a specific structure coupled with a bifunctional silicon or tin compound to achieve thermal properties that are excellent in various properties. It was developed after discovering that a melt-type adhesive can be obtained, and its purpose is to improve initial adhesive strength and peel strength when applied to adhesive sheets.

The object of the present invention is to provide a hot-melt pressure-sensitive adhesive composition that has excellent properties in terms of die-cutting properties and holding power.

That is, the adhesive composition of the present invention is a branched vinyl aromatic compound-conjugated diene copolymer obtained in a hydrocarbon solvent using an organolithium compound as an initiator, and the copolymer has the general formula % [Formula %] Among them, A is a vinyl aromatic compound polymer block.

B is a copolymer of a conjugated diene and a vinyl aromatic compound, and the B portion has (a) 0 to 10 tapered blocks in which the vinyl aromatic compound gradually increases.

(b) The weight ratio of vinyl aromatic compound/conjugated diene is 0 to 50/100 to 50.

Y is a residue of the general formula R, R, MX2 (in the formula, R, R, are H or CnH2n+t and n = 1
A block copolymer 100 characterized in that the integer X of ~20 is represented by halogen M is Si or Sn), and the total bonded vinyl aromatic compound of the copolymer is 5 to 70% by weight. parts by weight, 20 to 200 parts by weight of a tackifier, and 0 to 100 parts by weight of a softener.

The method for producing a block copolymer in the present invention is: - Using an organolithium compound as an initiator - In the presence of an ether or a tertiary amine compound - (a) First, 3 to 70% by weight of the vinyl aromatic compound is polymerized. 1 After the polymerization is substantially completed, (bl) A mixture consisting of 100 to 50% by weight of a conjugated diene and O to 50% by weight of a vinyl aromatic compound is added once or in 2 to 10 portions to make a 1M mixture. .

(C) Finally, the general formula % formula % [Formula hole 8. R2 is H or CnHzn+1 (n
= an integer of 1 to 20) X is CI or Br M is Si or Sn) It can be produced by adding a silicon or tin compound to perform a coupling reaction.

The block copolymer of the present invention contains 5 to 5 vinyl aromatic compounds.
70% by weight, preferably 5-50% by weight.

More preferably, the amount is 5 to 4 ON. If the amount of the vinyl aromatic compound is less than 1% (5 M), the holding power and die-cutting properties will be poor when used as an adhesive, and if it exceeds 70% by weight, the initial adhesive strength will be poor.

What does die-cutting mean here? - When manufacturing adhesive labels, a die is used to punch out the adhesive base material to form a label of the desired shape on the adhesive sheet pasted onto the peeling paper, and the unnecessary parts are removed from the peeling paper. At this time, if the die-cutting properties are poor, the adhesive base material will stick to the die, and the part needed as an adhesive label will be exposed and peeled off from the paper. This is the biggest drawback when applying heat-melting adhesives using coalescence to adhesive label applications.

A feature of the present invention is that after polymerizing a vinyl aromatic compound and a conjugated diene, a difunctional silicon or tin compound is added and a block copolymer coupled therewith is used.

Due to these characteristics, when the block copolymer of the present invention is used as a pressure-sensitive adhesive, the p-tackiness retention, peel strength, and die-cutting properties are significantly improved.

To produce the block copolymer of the present invention, first, a vinyl aromatic compound is polymerized in an amount of 5 to 70% by weight of the amount used in food.

If it is less than 5 M t 1, the holding power and die-cutting properties will be poor when used as an adhesive, and if it exceeds 70 weight 7 inches, the initial adhesive strength will be poor.

After the polymerization of the vinyl aromatic compound is substantially completed, a mixture consisting of 100 to 50 mft% of the conjugated diene and 0 to 50% by weight of the vinyl aromatic compound is then polymerized.

If the conjugated diene content is less than 50 mft%, the adhesive strength will be poor when used as an adhesive.

This polymerization is carried out by adding the above mixture once or in 2 to 10 times. After the polymerization of the conjugated diene is completed, 2
A functional silicon or tin compound is added to form a coupled block copolymer.

The amount of the difunctional silicon or tin compound added is 0.3 to 1 based on the lithium of the lithium end block copolymer.
．． It is 5 equivalents.

If the amount is less than 0.3 equivalents, or if it exceeds 1.5 equivalents, the holding power will be poor when used as an adhesive.

The vinyl aromatic compound used in the present invention includes:

Styrene, α-methylstyrene, p-methylstyrene,
m-methylstyrene, 0-methylstyrene Ip-ta
rt -7''f Rustyrene-dimethylstyrene, vinylnaphthalene, etc. can be used. Among these, styrene is preferred. Also, as the conjugated diene, butadiene isoprene, piperylene, etc. can be used. Among these, imprene is preferred.

The weight average molecular weight of the block copolymer of the present invention is preferably 10,000 to 500,000. More preferably 50
,000 to 400,000. Among these, the weight average molecular weight of the vinyl aromatic compound block part is 5,000~
50,000. The weight average molecular weight of the conjugated diene block portion is preferably 10,000 to 300,000.

The block copolymer of the present invention can also be produced by isothermal polymerization.

It can also be obtained by adiabatic polymerization. Further, a preferable polymerization temperature range is 30 to 120°C.

Examples of the hydrocarbon solvent used in the production of the block copolymer of the present invention include cyclopentane.

Cyclohexane, benzene, ethylbenyne, xylene and these together with pentane, hexane, heptane, butane
A mixture of the following is used.

Examples of organic lithium compounds include n-butyllithium r 5ec-butyllithium p tert-butyl!
j) n-hexyl lithium e tso-hexyl lithium, phenyl lithium, naphthyl lithium, etc., -E: 0.01 to 1 per 10 weight part of nomer
,0 parts by weight.

The silicon or tin compound used in the production of the block copolymer of the present invention has the general formula % [wherein R, , R2 is H2 or CnH2n+1 (
n - an integer of 1 to 20) X is a halogen such as (J or Br).

M is represented by Si or Sn), 2For example, dichlorosilane, heptadyldichlorosilane, dimethyldichlorosilane, monoethyldichlorosilane, diethyldichlorosilane, monobutyldichlorosilane-diptylddichlorosilane-monohexyldichlorosilane. Chlorosilane, dihexyldichlorosilane.

Dibromosilane, monomethyldibromosilane, dimethyldibromosilane, dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin,
Diethyldichlorotin - heptabutyldichlorotin, dibutyldibromtin, monohexyldichlorotin, etc. are used.

Particularly preferred examples include monomethyldichlorosilane, dimethyldichlorosilane, and monomethylsifuromsilane-dibromdichlorosilane.

A tackifier is blended into the block copolymer as described above. Examples of the tackifier include rosin resin, polyterpene resin/synthetic polyterpene resin, alicyclic hydrocarbon resin, and coumaron resin.

Phenol resins, terpene-phenol resins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins, etc. are used. Among these, rosin resins, polyterpene resins, and alicyclic hydrocarbon resins are particularly preferred. These tackifiers can be used alone or in combination of two or more.

The amount of the tackifier to be blended is 20 to 200 parts per 100 fUi parts of the copolymer, preferably 50 to 150 parts.
Parts by weight. If the amount of this tackifier is outside the above range, there is a risk that the initial adhesive strength and holding power will not be sufficient.

The adhesive composition of the present invention may further contain a softening agent. Examples of the softening agent include naphthenic and paraffinic softeners.
Aroma process oils and the like can be used alone or in combination of two or more. The amount of softener added is
The amount is 0 to 100 parts by weight, preferably 20 to 70 parts by weight, based on 100 parts by weight of the copolymer. The amount of softener added is 10
If the amount exceeds 0 parts by weight, the softener will ooze out onto the adhesive surface over the course of 2 hours, causing undesirable effects.

In addition to the above, the adhesive composition of the present invention may further contain antioxidants, stabilizers such as ultraviolet absorbers, calcium carbonate, talc, clay, titanium nitride, silica, magnesium carbonate, carbon black, etc. as necessary. Inorganic filler 9, coloring agent, etc. may be added.

The components of the adhesive composition described above are mixed in a general tank mixer, closed kneader, etc. 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, back printing for fixing various lightweight plastic molded products, and carpet fixing. Effective as back printing, etc.
Furthermore, it is effective as an adhesive layer forming material for frozen foods and adhesive tapes and labels used in cold regions.

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

The various measurements were conducted using the following methods.

The initial adhesion strength was determined by the inclined ball tack measurement method. Inclination angle 30°, measurement temperature 25°C0 exposure strength is JIS
Compliant with Z1522.

(180° constant speed (strength test, measurement temperature 25°C) The holding force was based on JIS Z1524. However, the pasting area was 15 x 10 m/m, and the time required for the IK2 weight to fall was Measurement temperature: 25°C0 The quality of die cutting was determined by the method shown below.In other words, high-quality paper was hot-melt coated with an adhesive to a predetermined thickness, and this was pasted on release paper.・
Cut into a size of 20α×43. Then 1.5αX 1
．． 5! After that, a total of 20 small pieces are punched out in two rows of 10 pieces so that only high-quality paper is cut using a punching blade of size .

When removing the excess from the paper by hand - Mark ○ when the number of adhesive labels that have come off is 0 to 1.

Mark Δ when there are 2 to 3 pieces, mark X when there are 4 or more pieces,
The quality of die cutting was judged.

Total styrene content was determined by infrared method.

Example 1 An autoclave equipped with a washed and dried stirrer and jacket was charged with 4.500 F of cyclohexane and Tetrahytronan II under a busy nitrogen atmosphere, and then the internal temperature was brought to 70'C.

Next, a hexane solution containing 0.4.9% of n-butyllithium was added, and 100% of styrene was added, followed by polymerization for 60 minutes.

The polymerization conversion rate of styrene was I00%. Then,
500.5"jlfAhD of isoprene was added and polymerized for 60 minutes. The polymerization conversion rate of isoprene was 100%.

Contains 0.36 g of monomethyldichlorosilane at the end.
A cyclohexane bath solution was added and a coupling reaction was carried out for 20 minutes.

During the polymerization, the temperature was always adjusted to 70°C. After the completion of the polymerization, the bipolymer solution IC2,6-sheet tert-butyl p-cresol was added.

Cyclohexane was removed by heating to obtain a block copolymer.

Examples 2 to 8 Comparative Examples 1 to 5 Polymerization was carried out according to the same recipe as in Example 1 using predetermined amounts of styrene, isopre/silicon compounds, etc. shown in Table 1.

The structure of the block copolymer is shown in Table 2, and the physical properties are shown in Table 3.

Note ■ Synthetic polyterpene resin.

Nippon Zeon vIIM-Quinton D-100■ Naphthenic process oil.

Manufactured by Idemitsu Kosan, Diana Process Oil Le NM-280 ■ Phenol-based anti-aging agent.

Manufactured by Ohmukai Shinko Kagaku ■, Tsukuraku NS- Examples 1 to 8 are superior to Comparative Examples 1 to 5 in terms of the balance between initial adhesive strength, peel strength, and die cutability.

Procedural amendment (voluntary) 1985 2
Month 4 El 1 Indication of the case Patent application No. 1983-163367 2 Name of the invention Hot melt adhesive composition 3 Person making the amendment

Claims (1)

[Scope of Claims] A vinyl aromatic compound-conjugated diene copolymer obtained using an organolithium compound as an initiator, the copolymer having the general formula (A-B)-_2Y [wherein A is a vinyl aromatic compound] The compound polymer block, B, is a copolymer of a conjugated diene and a vinyl aromatic compound, in which the B portion has (a) 0 to 10 tapered blocks in which the vinyl aromatic compound gradually increases, and (b) vinyl The weight ratio of aromatic compound/conjugated diene is 0~
50/100 to 50, and Y is a residue of the general formula R_1R_2MX_2 (wherein R_1 and R_2 are H or CnH_2n+1 and n
= an integer from 1 to 20, An adhesive composition comprising 100 parts by weight of a combination, 20 to 200 parts by weight of a tackifier, and 0 to 100 parts by weight of a softener.