JPH0978047A - Hot melt pressure sensitive adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hot melt pressure sensitive adhesive composition having excellent initial tackiness, adhesive property and holding power as well as conventional technique and useful for a sanitary material having improved processability by low viscosity, especially for a paper diaper or a sanitary napkin. SOLUTION: This hot melt pressure sensitive adhesive composition is composed of (A) 100 pts.wt. of a block copolymer of the formula: (A1 -B1 )k X A1 is a polymer block mainly composed of an aromatic vinyl compound, B1 is a polymer block mainly composed of conjugated diene, X is a residue of a phosphorus-based compound coupling agent of the formula: [(Cn H2n+1 )p -ϕm -O-]3 or [(Cn H2n+1 )p -ϕm -O-]3 P=O, (k) is an integer of 1-3, (n) is an integer of 0-20, (m) is 0 or 1, (p) is 1 or 2, (n) is 0 when (m) is 1, (n) is an integer of 1-20 when (m) is 0, (ϕ) is a benzene nucleus}, (B) 40-300 pts.wt. of a tackifier resin, (C) 0-200 pts.wt. of a softener and (D) 0.1-5 pts.wt. of a stabilizer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hot-melt pressure-sensitive adhesive composition, and more particularly to a hot-melt pressure-sensitive adhesive composition having excellent processability, excellent initial pressure-sensitive adhesiveness, adhesive strength, holding power balance and heat stability. The present invention relates to a hot-melt pressure-sensitive adhesive composition suitable for pressure-sensitive adhesives, particularly pressure-sensitive adhesives used for paper diapers, sanitary napkins and the like.

[0002]

2. Description of the Related Art Conventionally, generally, the application of an adhesive to a substrate is
A method of applying a solution in which an adhesive is dissolved in a solvent by a roll, a spray, or the like is adopted. However, the use of this solvent has many problems in terms of air pollution, fire, working environment and hygiene, and in recent years, it has been regarded as a serious social problem. Therefore, as a means for solving this inconvenience, a non-solvent type hot-melt pressure-sensitive adhesive has recently attracted attention.

The base polymer of the hot melt adhesive is an ethylene-vinyl acetate copolymer, a block copolymer of an aromatic vinyl compound and a conjugated diene and its hydrogenated product, an ethylene-α-olefin copolymer, a polyester. Various polymers such as resins have been used. Above all,
A block copolymer composed of an aromatic vinyl compound and a conjugated diene has a long open time and a relatively good balance between adhesiveness and holding power, and thus is particularly preferably used as an adhesive for disposable sanitary materials. There is.

For example, Japanese Examined Patent Publication No. 44-17037,
Japanese Patent Publication No. 45-41518 discloses polystyrene-polybutadiene-polystyrene or polystyrene-
A linear block copolymer adhesive composition such as polyisoprene-polystyrene is disclosed. Further, Japanese Patent Publication No. 56-49958 discloses a hot-melt pressure-sensitive adhesive composition using a branched chain block copolymer of (polystyrene-polybutadiene) _n X. Actually, the hot-melt pressure-sensitive adhesive composition using the block copolymer of styrene and a conjugated diene as described above is used, for example, for adhesion between a nonwoven fabric of a disposable diaper and a polyethylene substrate.

However, the pressure-sensitive adhesive composition composed of this block copolymer generally has a high melt viscosity and is inferior in processability, has a low coating step speed, and requires a relatively high coating temperature. Has become. Attempts have been made to date for hot-melt pressure-sensitive adhesive compositions having an excellent balance of processability and physical properties, and for example, JP-A-58-89.
No. 672, JP-A-1-266156, etc., a hot-melt pressure-sensitive adhesive using a (polystyrene-conjugated diene) _n X multibranched block copolymer, which is excellent in workability, that is, in balance between processability and physical properties. Agent compositions are disclosed. However, it is still insufficient as a material, such as the possibility of heat deterioration of the adhesive and the base material and the heat resistance of the usable material, and excellent thermal stability.
A hot-melt pressure-sensitive adhesive composition that gives a lower melt viscosity in the actual processing temperature range is desired.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. While maintaining the balance of initial tackiness, adhesiveness and holding power as in the prior art,
It is an object of the present invention to provide a hot melt pressure-sensitive adhesive composition having excellent heat stability and a sufficiently low hot melt melt viscosity.

[0007]

In view of the present situation, the present inventors have found that a hot-melt pressure-sensitive adhesive composition containing a block copolymer composed of an aromatic vinyl compound polymer block and a conjugated diene polymer block is hot. As a result of diligent study on improvement in viscosity reduction and thermal stability at melt processing temperature, molecular structure, aromatic vinyl compound content,
It has been found that the object can be achieved by using a block copolymer in which the molecular weight and the molecular weight of the aromatic vinyl compound polymer block are within a specific range, and the present invention has been completed.

That is, the present invention provides (A) general formula (I); (A ₁ -B ₁ ) _k X {wherein A ₁ is a weight average molecular weight of 6,000 to
11,000 is a polymer block mainly containing an aromatic vinyl compound, B ₁ is a polymer block mainly containing a conjugated diene, and (A ₁ -B ₁ ) has a weight average molecular weight of 20,000 to
70,000, X is a general formula [(C _n H _{2n + 1} ) _p −φ _m −
O−] ₃ P or [(C _n H _{2n + 1} ) _p −φ _m −O−] ₃
P = O (In the formula, n is an integer of 0 to 20, m is 0 or 1,
p is 1 or 2, but when n is 0, m is 1 and m is 0
Where n is an integer of 1 to 20, φ represents a benzene nucleus), the residue of the phosphorus compound coupling agent represented by k, and k is 1 to
It is an integer of 3 and the total bond content of A ₁ is 10 to 40% by weight. The proportion of the diblock in the block copolymer component is 70% by weight or less. } 100 parts by weight of the block copolymer represented by the formula (B) 40 to 300 parts by weight of tackifier resin, 0 to 200 parts by weight of (C) softener, and 0.1 to 5 of stabilizer (D). The present invention provides a hot-melt pressure-sensitive adhesive composition, characterized by containing parts by weight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The block copolymer (A) used in the present invention is a block copolymer represented by the general formula (I); (A ₁ -B ₁ ) _k X ₁ is a polymer block mainly composed of an aromatic vinyl compound having a weight average molecular weight of 6,000 to 11,000, B ₁ is a polymer block mainly composed of a conjugated diene, and A ₁ -B _{1 has} a weight average molecular weight of 2
50,000 to 70,000, X is a general formula [(C
_n H _{2n + 1} ) _p −φ _m −O−] ₃ P or [(C
_n H _{2n + 1} ) _p −φ _m −O−] ₃ P═O (where n is 0 to
An integer of 20, m is 0 or 1, p is 1 or 2, provided that when n is 0, m is 1, when m is 0, n is an integer from 1 to 20, and φ represents a benzene nucleus). The residue of the phosphorus compound coupling agent, k is an integer of 1 to 3, the total bond content of A ₁ is 15 to 40% by weight, and the proportion of diblock in the block copolymer component is 70% by weight. % Or less.

In the general formula (I), the polymer block A ₁ is
It is a polymer block mainly composed of an aromatic vinyl compound, and may be one obtained by copolymerizing less than 50% by weight of a conjugated diene. Further, in the general formula (I), the polymer block B ₁
Is a polymer block containing a conjugated diene as a main component, a homopolymer of a conjugated diene, a copolymer of two or more conjugated dienes, or a conjugated diene containing 50% by weight or more of a conjugated diene and an aromatic vinyl compound. Is a copolymer block with. The aromatic vinyl compound which may be present in the polymer block B ₁ may be uniformly dispersed or may be distributed in a taper shape. A plurality of the uniformly distributed portions and / or the tapered distribution portions may coexist in the polymer block B ₁ .

Here, the aromatic vinyl compound used to obtain the block copolymer (A) is styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-. Diphenyl styrene, N, N-diethyl-p-aminoethyl styrene, vinyl pyridine, etc. are mentioned, Preferably styrene is mentioned. These may be used not only as one type but also as a mixture of two or more types.

Further, as the conjugated diene used for obtaining the block copolymer (A), 1,3-butadiene, isoprene, 2,3-dimethyl-1,3 butadiene, 1,3-pentadiene, 2- Methyl-1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3
-Hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene and the like can be mentioned, with preference given to 1,3-butadiene or isoprene. These are not only one, but two
Mixtures of more than one species may be used.

In the general formula (I), the polymer block A _{1 has} a weight average molecular weight of 6,000 to 11,000, preferably 7,000 to 10,000. When the weight average molecular weight is less than 6,000, the melt viscosity is low and the processability is excellent, but the physical properties of the obtained hot-melt pressure-sensitive adhesive composition, particularly the holding power, are deteriorated, which is not preferable. On the other hand, if it exceeds 11,000, the viscous adhesive force and the cohesive force can be satisfied, but the melt viscosity in the hot melt processing temperature range becomes high and the workability becomes poor, such being undesirable.

(A) A block copolymer (A ₁ -B)
The weight average molecular weight of _{1) k} X in the block (A ₁ -B ₁₎ is 20,000 to 70,000 preferably 30,00
It is 0 to 65,000. When the weight average molecular weight is less than the above, the melt viscosity of the obtained hot-melt pressure-sensitive adhesive composition is sufficiently low, but the properties as a pressure-sensitive adhesive are deteriorated, which is not preferable. On the other hand, when the weight average molecular weight exceeds the above value, the viscosity of the pressure-sensitive adhesive composition is high and the processability is poor, which is not preferable. The total bond content of A ₁ of the (A) block copolymer is
It is 10 to 40% by weight, preferably 20 to 35% by weight. When the total bond content of A ₁ exceeds the above range, the initial tackiness of the obtained hot melt pressure-sensitive adhesive composition is lowered, which is not preferable. On the other hand, if the total bond content of A ₁ is less than the above range, the physical properties of the obtained pressure-sensitive adhesive composition, particularly the holding power, are deteriorated, which is not preferable.

If the block copolymer (A) used in the present invention satisfies the above general formula (I),
Not only one kind may be used alone, but two or more kinds may be used as a mixture.

The method for producing the block copolymer (A) used in the present invention is obtained by anionic polymerization using an organolithium compound as an initiator in a hydrocarbon solvent. This production method is known in the technical field of anionic polymerization, and for example, JP-B-36-19286, JP-B-40-23798, JP-B-40-24915, JP-B-43-17979 and JP-B-4317979. 45-31
951 gazette, Japanese Patent Publication No. 46-32415, Japanese Patent Publication No. 47
The methods described in JP-A-14132, JP-A-61-291610, and JP-A-62-64806 can be mentioned, but it is necessary to select the conditions satisfying the range defined above. Don't

In the polymerization method using an organic lithium compound as an initiator, the hydrocarbon solvent is butane, pentane,
Aliphatic hydrocarbons such as hexane, isopentane, heptane, octane, isooctane, alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane and ethylcyclohexane, or aromatics such as benzene, toluene, ethylbenzene and xylene One or more inert hydrocarbon solvents such as hydrocarbons can be used in combination, but cyclohexane is preferred. Specific examples of the organic lithium compound include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium and the like.

In the present invention, the block copolymer (A) is polymerized using a coupling agent (AB) _k X.
(X is the phosphorus compound coupling agent residue, k is 1 to
It is represented by an integer of 3), but contains an unreacted unreacted AB block copolymer, or the coupling is incomplete, and k is less than or equal to the functional number of the coupling agent. It should be noted that ingredients may be included. (A) In the block copolymer, (A ₁ -B ₁ )
The proportion of ₁ or (A ₁ -B ₁ ) ₁ X component, that is, the diblock component, is 70% by weight or less, preferably 60%.
% By weight or less. When the amount of the diblock component in the block copolymer (A) exceeds 70% by weight, the melt viscosity is low and the processability is excellent, but the adhesive property, especially the holding power is extremely lowered, which is not preferable.

Further, the phosphorus-based compound used as a coupling agent of the general formula _{[(C n H 2n + 1)} p -φ m -O- ] ₃ P or _{[(C n H 2n + 1)} , p -φ _m -O-] ₃ P = O (wherein, n 0 to 20 integer, m is 0 or 1, p is 1
Or 2, provided that when n is 0, m is 1, when m is 0, n is an integer of 1 to 20, and φ represents a benzene nucleus). Specific examples of the phosphorus-based compound include trimethyl phosphonate, triethyl phosphonate, tripropyl phosphonate, tributyl phosphonate, pentyl phosphonate, hexyl phosphonate, triphenyl phosphonate, trimethyl phosphate, triethyl phosphate, and triphosphate. Examples thereof include propyl, tributyl phosphate, triphenyl phosphate, trisnonylphenyl phosphonate, trisnonylphenyl phosphate, and tris (2,4-di-t-butylphenyl) phosphonate. Of these, particularly preferred is n when m = 0 in the general formula.
= 1 to 20 and n = 0 to 10 when m = 1. Particularly preferred specific examples include trisnonylphenyl phosphonate, triphenyl phosphate and triethyl phosphate. The addition amount of the above-mentioned phosphorus compound is usually 0.3-based on the lithium of the lithium end block copolymer.
1.5 equivalents can be used.

At this time, a Lewis base such as ether or amine, specifically diethyl ether, tetrahydrofuran, propyl ether, butyl ether or higher ether is used as a regulator of the microstructure, that is, the vinyl bond content of the conjugated diene moiety. In addition, ether derivatives of polyethylene glycol such as ethylene glycol butyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, triethylene glycol butyl ether, and ethylene glycol dibutyl ether, and tertiary amines such as tetramethylethylenediamine, pyridine, and tributylamine as amines. , Used with inert hydrocarbon solvents.

The polymerization reaction is usually carried out at 20 to 120 ° C, preferably 30 to 100 ° C. Further, the polymerization may be carried out while controlling at a constant temperature, or may be carried out at an elevated temperature without heat removal.

By further adding the above-mentioned phosphorus compound coupling agent to the thus obtained block copolymer living anion, a block copolymer (A) having an extended polymer molecular length can be obtained.

The bond content of the aromatic vinyl compound in the block copolymer component (A) is adjusted by adjusting the amount of the monomer supplied during the polymerization in each stage, and is adjusted as necessary. The vinyl bond of the conjugated diene is adjusted. The content is adjusted by varying the components of the microregulator. The vinyl bond content of the conjugated diene is usually preferably 10 to 60% when the conjugated diene is butadiene and 5 to 50% when the conjugated diene is isoprene. The weight average molecular weight of the block copolymer component (A) is adjusted by the addition amount of a polymerization initiator, for example, n-butyllithium.

Next, the tackifier resin (B) used in the present invention has been conventionally used as a tackifier for hot melt pressure sensitive adhesives and the like. For example, coumarone indene resin and phenol. Resin, pt-butylphenol / acetylene resin, phenol / formaldehyde resin, terpene / phenol resin, polyterpene resin, xylene / formaldehyde resin, synthetic polyterpene resin, aromatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, monoolefin and diolefin Olefin oligomer, hydrogenated hydrocarbon resin, hydrocarbon resin, polybutene, polyhydric alcohol ester of rosin, hydrogenated rosin, hydrogenated wood rosin, ester of hydrogenated rosin with monoalcohol or polyhydric alcohol, turpentine tackifier Agents and the like. Particularly suitable tackifiers are terpene resins, synthetic terpene resins, aromatic modified polyterpene resins, aliphatic saturated petroleum resins, rosin esters, disproportionated rosin esters, hydrogenated rosin esters, aliphatic petroleum resins ( C ₅ -based aliphatic petroleum resin, C ₅ and C ₉ aliphatic-based petroleum resin, etc.) and modified aliphatic petroleum resin. The compounding amount of the (B) tackifier resin is 40 to 300 parts by weight, preferably 60 to 300 parts by weight, relative to 100 parts by weight of the (A) block copolymer. If the compounding amount of the (B) tackifier resin is out of the above range, the adhesive property is poor and it is not preferable.

Examples of the (C) softener used in the present invention include petroleum-based softeners such as paraffin-based, naphthene-based, and aroma-based process oils, paraffins, vegetable oil-based softeners, and plasticizers. They can be used alone or in combination of two or more. The compounding amount of the (C) softening agent is 0 to 200 parts by weight, preferably 0, to 100 parts by weight of the (A) block copolymer.
１００100 parts by weight. When the amount of the softening agent exceeds 200 parts by weight, not only the holding power of the obtained hot-melt pressure-sensitive adhesive composition at high temperature lowers but also the softening agent exudes to the adhesive surface with the passage of time, which has an unfavorable effect. .

Next, the stabilizer (D) used in the present invention includes phenolic stabilizers, sulfur stabilizers, phosphorus stabilizers and the like, which may be used alone or in combination. Phenol stabilizers include 2,6-di-t-butyl-p-cresol, pentaerythritol-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenol) propionate] methane, stearyl ( Three
5-di-t-butyl-4-hydroxyphenyl) propionate, thiodiethylene glycol bis [(3,5-
Di-t-4-hydroxyphenyl) propionate],
4,4'-thiobis (6-t-butylphenol),
2,2'-methylenebis (4-methyl-6-di-t-butylphenol), 1,1,3-tris (2-methyl-)
4-hydroxy-5-t-butylphenyl) butane,
1,3,5-Tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-Tris (3,5-di-t-butyl-4-hydroxybenzyl)- 2,4,6-trimethylbenzene, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,
5-di-t-butylanilino) -1,3,5-triazine, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-
Pentylphenyl acrylate, 3,9-bis (1,1
-Dimethyl-2-hydroxyethyl) -2,4,8,1
0-tetraoxaspiro [5.5] undecane-bis [β- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate] and the like can be mentioned.

Examples of the sulfur stabilizer include pentaerythrityl tetrakis (3-lauryl thiopropionate) and distearyl 3,3'-thiodipropionate. Further, phosphorus-based stabilizers include trisnonylphenyl phosphite and tris (2,4-di-t
-Butylphenyl) phosphite and the like can be mentioned. In addition to these stabilizers, stabilizers such as amine-based stabilizers and ultraviolet absorbers, stabilizers such as epoxy compounds and hydrotalcite can also be used. The compounding amount of these (D) stabilizers is 0.1% as a total amount of the stabilizer with respect to 100 parts by weight of the (A) block copolymer.
It is 1 to 5 parts by weight, preferably 0.5 to 3 parts by weight.
If the amount is less than 0.1 parts by weight, thermal stability is insufficient and thermal deterioration occurs during hot melt processing, which is not preferable. On the other hand, even if it exceeds 5 parts by weight, the thermal stability at the time of hot melt processing is the same as 5 parts by weight, and the cost increases, which is not preferable.

In the present invention, as the reinforcing resin, polystyrene, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer and thermoplastic resin having a relatively low molecular weight are used. A polyester resin, a polyamide resin, a polyphenylene ether resin or the like is used in an amount of 50 parts by weight or less, preferably 2 to 100 parts by weight of the (A) block copolymer.
By blending 40 parts by weight, creep resistance and hardness can be improved. If the content of the reinforcing resin exceeds 50 parts by weight,
It is not preferable because it lowers the adhesive property. If necessary, inorganic fillers such as calcium carbonate, talc, titanium oxide, silica and magnesium carbonate, and waxes such as paraffin wax and low molecular weight polyethylene wax may be added.

Further, the hot-melt pressure-sensitive adhesive composition of the present invention may contain other common elastomers such as natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, as long as the properties of the pressure-sensitive adhesive are not lost. A mixture of chloroprene rubber, ethylene-propylene rubber, acrylic rubber, polyisoprene isobutylene rubber, acrylonitrile-butadiene rubber, or an aromatic vinyl compound / conjugated diene block copolymer or hydrogenated product thereof other than those specified in the present invention is mixed. You may use it.

A pressure-sensitive adhesive composition can be obtained by kneading the above components by a conventional method. The conditions of kneading are not particularly limited, and known methods such as a general tank mixer, a closed kneader, an extruder, etc., in a nitrogen gas atmosphere, if necessary, usually in the range of 130 ° C to 200 ° C. Kneading is carried out.

[0031]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, parts and% are based on weight unless otherwise specified. Moreover, various evaluations in the examples are obtained as follows.

Characteristic weight average molecular weight (Mw) of block copolymer GPC apparatus [Tosoh Corp., HLC-8020 type is used, and the column is ZORBAX made by DuPont (USA).
The weight average molecular weight is the value measured with standard polystyrene and converted into standard polystyrene. As measurement conditions, tetrahydrofuran as a mobile phase, a flow rate of 1.0 ml / min,
The measurement was performed at a measurement temperature of 40 ° C. Amount of bound styrene It was determined from the absorption intensity at 699 cm ⁻¹ using an infrared spectrophotometer (Perkin Elmer 1600 type).

Characteristic Melt Viscosity of Hot Melt Adhesive Composition As a measure of workability, it was measured at 140 ° C. with a B-type viscometer. Adhesive strength A polyester film substrate is coated with an adhesive composition having a coating thickness of 40 μm to prepare an adhesive tape, and then JIS Z-
According to 1522, stainless steel plate, width 25mm x length 1
The adhesive tape was attached at a size of 00 mm, and peeled in the direction of 180 ° at a speed of 300 mm / min at 23 ° C. and measured. Initial Adhesion A polyester film substrate is coated with an adhesive composition having a coating thickness of 40 μm to prepare an adhesive tape, and then the ASTM
According to D2979-71, Polyken probe tack was measured, a stainless steel plate was adhered to the adhesive tape having a width of 25 mm and a length of 100 mm at a speed of 300 mm / min, left for 3 seconds, and then peeled at a speed of 300 mm / min. Loop tack was measured.

Cohesive force: 25 mm on a stainless steel plate according to JIS Z-1524
The adhesive tape was attached so that the areas of × 25 mm were in contact with each other, and the time until the adhesive tape slips off by applying a load of 1 kg at 40 ° C. was measured as a holding force. Heat stability 40 g of the obtained hot melt adhesive composition was put in a 100 cc mayonnaise bottle and placed in an oven at 120 ° C. for 24 hours.
Immediately after standing for 5 hours, length 5 cm x width 5 cm x depth 2
It was poured into a container made of a Teflon (polytetrafluoroethylene) sheet having a size of 1 cm so as to have a depth of 1 cm, and cooled as it was. After cooling, the melt viscosity was measured with a B-type viscometer at 140 ° C., and the viscosity retention ratio was calculated as the ratio of the viscosity before the above treatment (viscosity after leaving in oven) / (viscosity before leaving in oven). Thermal stability was measured.

Example 1 Preparation of Block Copolymer A polymerization vessel made of stainless steel having an inner volume of 5 liter and equipped with a jacket and a stirrer was sufficiently replaced with nitrogen gas, and then 2,500 g of cyclohexane and 125 g of styrene were charged.
The contents were brought to 40 ° C by passing warm water through the jacket. Then, a cyclohexane solution containing 0.3 g of sec-butyllithium was added to initiate polymerization. After the completion of styrene polymerization, 375 g of isoprene was slowly added while passing cold water through the jacket so that the temperature of the contents became 80 ° C. After the polymerization of isoprene was completed, a cyclohexane solution containing 1.2 g of trisnonylphenylphosphite was added and a coupling reaction was carried out for 20 minutes to complete the polymerization.

After the reaction, 0.1 ml of methanol was added and the mixture was stirred for 10 minutes, then the contents were taken out of the polymerization vessel and the antioxidant 4-[(4,6-bis (octylthio) -s-triazine-] was added. 2-yl) amino] -2,6
-Di-t-butylphenol [Ciba Geigy Co., Ltd.,
0.5 g of Irganox 565] and 1.5 g of tris (nonylphenyl) phosphite (TNPP) were added. The polymerization solution was steam stripped in hot water having a pH of 5 to 7 and the resulting hydropolymer was dried to obtain styrene-isoprene block copolymers shown in Tables 1 and 2.

Preparation of Hot Melt Adhesive Composition Based on 100 parts of the block copolymer obtained as described above, 220 parts of tackifier resin [CLEARON P105, manufactured by Yasuhara Chemical Co., Ltd.], paraffin-based process oil [Idemitsu] Dyna Process Oil PW manufactured by Kosan Co., Ltd.
-90] 80 parts, tetrakis [methylene as a stabilizer
3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane [manufactured by Ciba-Geigy Co., Ltd.,
3 parts of Irganox 1010] was put into a kneader heated to 150 ° C., and mixed for 30 minutes to obtain a hot melt adhesive composition. Table 3 shows the evaluation results of each characteristic.

Example 2 In Example 2, the block copolymers (A) shown in Tables 1 and 2 were obtained in the same manner as in Example 1 except that the charged amounts of sec-butyllithium, styrene and isoprene were changed. , A hot-melt adhesive composition was prepared and each property was evaluated. The results are shown in Table 3.

Example 3 Example 3 is similar to Example 1 except that the coupling agent was changed to trisphenyl phosphate and the charged amounts of sec-butyllithium, styrene and isoprene were changed. The block copolymer (A) shown in 2 was obtained, a hot-melt pressure-sensitive adhesive composition was prepared, and its performance was evaluated.
The results are shown in Table 3.

Example 4 Example 4 is the same as Example 1 except that butadiene was used instead of isoprene and the charging amount of sec-butyllithium was changed, and the (A) block shown in Tables 1 and 2 was used. Obtain a copolymer, create a hot melt pressure sensitive adhesive composition,
Each property was evaluated. The results are shown in Table 3.

Example 5 In Example 5, the block copolymers (A) shown in Tables 1 and 2 were obtained in the same manner as in Example 1 except that the charged amounts of styrene and isoprene were changed. A composition was prepared and each property was evaluated. The results are shown in Table 3.

Comparative Examples 1-5 Comparative Examples 1-5 are sec-butyllithium, styrene,
Except for changing the charging amounts of isoprene and the coupling agent, the (A) block copolymers shown in Tables 1 and 2 were obtained in the same manner as in Example 1 to prepare a hot melt pressure sensitive adhesive composition,
Each property was evaluated. The results are shown in Table 3.

Comparative Example 6 In Comparative Example 6, the coupling agent was changed to silicon tetrachloride,
As in Example 1, except that the charged amount was changed.
The (A) block copolymer shown in 2 was obtained, a hot-melt pressure-sensitive adhesive composition was prepared, and each property was evaluated. The results are shown in Table 3.

It can be seen from Tables 1 to 3 that the hot melt pressure sensitive adhesive composition defined in the present invention has improved processability due to its low melt viscosity and exhibits good pressure sensitive adhesive physical properties. On the other hand, Comparative Example 1 is an example in which the molecular weight of the block mainly composed of the aromatic vinyl compound of the block copolymer (A) is below the lower limit, and the melt viscosity of the obtained hot melt adhesive composition is sufficiently high. Although it is low and excellent in workability, it is inferior in physical properties as an adhesive, resulting in an unfavorable result. Comparative Example 2, on the contrary, is an example in which the molecular weight of the block mainly composed of the aromatic vinyl compound of the block copolymer (A) exceeds the upper limit. Although it has good physical properties as an adhesive, it has an extremely high melt viscosity and is inferior in processability in hot melt.

Comparative Example 3 is an example in which the amount of bound styrene in the block copolymer (A) is below the lower limit and the weight average molecular weight of the diblock component before coupling exceeds the upper limit, but it is compared with the Examples. Has a relatively high melt viscosity, holding power,
It can be seen that the adhesive strength is poor and the balance between the processability and physical properties of the two is poor. Contrary to Comparative Example 3, Comparative Example 4 is an example in which the amount of bound styrene exceeds the upper limit of the range specified in the present invention, and the weight average molecular weight of the (A) block copolymer before coupling is below the lower limit. It can be seen that the initial tackiness is inferior to the examples. Comparative Example 5
This is an example in which the proportion of the diblock in the block copolymer (A) in the weight exceeds 70%, but the holding power and the adhesive force are significantly reduced as compared with the present invention, and the hot temperature specified in the present invention is high. It is shown that the balance between processability and physical properties is inferior as compared with the melt pressure-sensitive adhesive composition. Comparative Example 6 is an example in which a coupling agent other than those specified in the present invention was used, and it is shown that the thermal stability is poor.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

According to the present invention, initial tackiness, adhesiveness,
A hot-melt pressure-sensitive adhesive composition having excellent thermal stability and a sufficiently low hot-melt melt viscosity can be obtained while maintaining the balance of holding power as in conventional techniques.

Front page continuation (72) Inventor Kunihiko Takiguchi 34 Higashiwada, Kamisu-cho, Kashima-gun, Ibaraki JYS Earl Shell Elastomer Co., Ltd. Shell elastomer stock company

Claims (1)

[Claims] 1. (A) General formula (I); (A ₁ -B ₁ ) _k
X {in the general formula (I), A ₁ is a weight average molecular weight of 6,000 to
11,000 is a polymer block mainly containing an aromatic vinyl compound, B ₁ is a polymer block mainly containing a conjugated diene, and (A ₁ -B ₁ ) has a weight average molecular weight of 20,000 to
70,000, X is a general formula [(C _n H _{2n + 1} ) _p −φ _m −
O−] ₃ P or [(C _n H _{2n + 1} ) _p −φ _m −O−] ₃
P = O (In the formula, n is an integer of 0 to 20, m is 0 or 1,
p is 1 or 2, but when n is 0, m is 1 and m is 0
Where n is an integer of 1 to 20, φ represents a benzene nucleus), the residue of the phosphorus compound coupling agent represented by k, and k is 1 to
It is an integer of 3 and the total bond content of A ₁ is 10 to 40% by weight. The proportion of the diblock in the block copolymer component is 70% by weight or less. } 100 parts by weight of the block copolymer represented by the formula (B) 40 to 300 parts by weight of tackifier resin, 0 to 200 parts by weight of (C) softener, and 0.1 to 5 of stabilizer (D). A hot-melt pressure-sensitive adhesive composition, characterized by containing parts by weight.