HK1105212B - Adhesive composition - Google Patents

Description

Adhesive composition

Technical Field

The present invention relates to an adhesive composition. In particular, it relates to an adhesive composition having excellent low-temperature processability and extremely excellent appearance, adhesive properties and heat resistance.

Background

In recent years, hot melt adhesives have been widely used from the viewpoints of energy saving, resource saving, reduction in environmental load, and the like, and block copolymers (SBS, SIS, and the like) composed of a monoalkenyl aromatic compound and a conjugated diene compound have been widely used as base polymers of hot melt adhesives. However, an adhesive composition obtained by using these block copolymers is insufficient in balance among holding power, tackiness and processability, and it is desired to improve these. As a method for improving this, for example, Japanese patent application laid-open No. 61-278578 discloses an adhesive composition comprising a triblock copolymer and a diblock copolymer. In addition, Japanese patent application laid-open No. Sho 63-248817 discloses an adhesive composition containing a block copolymer obtained by coupling a specific bifunctional coupling agent (specific dihalide).

Patent document 1: japanese laid-open patent publication No. 61-278578

Patent document 2: japanese laid-open patent publication No. 63-248817

However, recently, the performance required of hot melt adhesives is more advanced and complicated, and for example, adhesives used in sanitary materials such as disposable diapers and sanitary napkins are required to exhibit various performances such as transparency, heat discoloration resistance, deodorization, and low viscosity from the viewpoint of appearance, hygienic property, and processability. In order to meet the demand for improvement in the adhesive application technique and the resultant increase in productivity of the final product, the viscosity of the adhesive composition is required to be low, and a hot melt adhesive having excellent applicability at a lower temperature is required to maintain the strength of the adherend.

However, SBS, for example, has a vinyl bond in the conjugated diene chain and is generally poor in heat resistance, and when the viscosity of an adhesive is lowered at a high temperature to improve processability, for example, discoloration may occur due to heat, and appearance of the adhesive composition may be deteriorated due to gelation or thermal decomposition, resulting in deterioration of adhesive performance. On the other hand, when the adhesive composition is processed at a low temperature in order to suppress such thermal discoloration or thermal degradation, the melt viscosity increases, and the processing becomes difficult. In addition, when processability is a problem, a method of adding a large amount of a softening agent or a method of reducing the blending amount of a block copolymer may be employed in order to improve such a problem, but these measures often cause a decrease in the balance of adhesive properties, bleed out of the softening agent, and a decrease in the appearance and hygiene of the adhesive composition. Further, when the molecular weight of SBS is reduced alone, the thermal discoloration and processability of the resulting adhesive can be improved, but the performance of the adhesive is extremely reduced, which is not preferable.

Disclosure of Invention

The present invention has been made to solve the problems associated with the conventional adhesive compositions as described above, and an object of the present invention is to provide an adhesive composition having excellent processability at low temperature, and particularly having extremely excellent appearance, adhesive performance, and heat resistance.

The present inventors have made intensive studies to solve the above problems and as a result, have found that an adhesive composition containing a block copolymer of a specific monoalkenyl aromatic compound and a conjugated diene compound is extremely excellent in low-temperature processability, and have achieved the above object, and finally have completed the present invention.

That is, the present invention achieves the above object by providing the following adhesive composition.

An adhesive composition comprising a block copolymer composition (A),

the block copolymer composition (A) comprises a block copolymer (a) and a block copolymer (b), wherein the block copolymer (a) comprises at least two polymer blocks mainly comprising a monoalkenyl aromatic compound and at least one polymer block mainly comprising a conjugated diene; the block copolymer (b) comprises at least one polymer block mainly comprising a monoalkenyl aromatic compound and at least one polymer block mainly comprising a conjugated diene,

the peak molecular weight of the block copolymer (a) measured by GPC is 6 to 11 ten thousand in terms of standard polystyrene,

the peak molecular weight of the polymer block mainly composed of a monoalkenyl aromatic compound constituting the block copolymer composition (A) is 1 to 3 ten thousand, the molecular weight distribution Mw/Mn is 1.0 to 1.6,

the block copolymer composition (A) having a total monoalkenyl aromatic compound content of more than 40% by weight to not more than 50% by weight,

the block copolymer composition (A) contains 50 to 90 wt% of a block copolymer (b),

in the block copolymer composition (A), the vinyl bond content of the conjugated diene portion is less than 20%,

the block copolymer composition (A) has a 15% toluene solution viscosity of 10 to 40cP at 25 ℃.

Detailed Description

The present invention is described in detail below.

The component (A) constituting the present invention is a block copolymer composition comprising a block copolymer (a) and a block copolymer (b), wherein the block copolymer (a) comprises at least two polymer blocks mainly comprising a monoalkenyl aromatic compound and at least one polymer block mainly comprising a conjugated diene; the block copolymer (b) comprises at least one polymer block mainly comprising a monoalkenyl aromatic compound and at least one polymer block mainly comprising a conjugated diene.

The polymer block mainly composed of a monoalkenyl aromatic compound means a homopolymer block of a monoalkenyl aromatic compound or a copolymer block mainly composed of a monoalkenyl aromatic compound and containing 50% by weight or more of the monoalkenyl aromatic compound. The polymer block mainly composed of a conjugated diene compound means a homopolymer block of a conjugated diene compound or a copolymer block mainly composed of a conjugated diene compound and containing 50% by weight or more of a conjugated diene compound. In the case where the conjugated diene compound-based copolymer block is, for example, a monoalkenyl aromatic compound-conjugated diene compound copolymer, the monoalkenyl aromatic compound in the copolymer block may be uniformly distributed or may be non-uniformly distributed (for example, in a tapered shape). In each block, a plurality of uniformly distributed portions and/or a plurality of non-uniformly distributed portions may coexist.

Examples of the monoalkenyl aromatic compound used in the block copolymers (a) and (b) include monomers such as styrene, p-methylstyrene, t-butylstyrene, α -methylstyrene, and 1, 1-diphenylethylene, and styrene is preferable among them. These monomers may be used alone or in combination of 2 or more.

On the other hand, examples of the conjugated diene compound include monomers such as 1, 3-butadiene, isoprene, 2, 3-dimethyl-1, 3-butadiene, 3-butyl-1, 3-octadiene, and phenyl-1, 3-butadiene, among which 1, 3-butadiene and isoprene are preferable, and 1, 3-butadiene is most preferable. These monomers may be used alone or in combination of 2 or more.

The content of the total bonded monoalkenyl aromatic compound contained in the block copolymer composition (a) is more than 40% by weight from the viewpoint of productivity and blocking resistance of the block copolymer composition, and the holding power performance and heat resistance of the obtained adhesive composition, and is 50% by weight or less from the viewpoint of tackiness of the obtained adhesive composition. Preferably from greater than 40% to no more than 48% by weight.

The content of the block copolymer (b) constituting the block copolymer composition (A) of the present invention is 50% by weight or more from the viewpoint of adhesive properties such as melt viscosity and tackiness of the obtained adhesive composition, and 90% by weight or less from the viewpoint of mechanical strength, rubber elasticity, blocking resistance of the obtained block copolymer composition and holding power properties of the obtained adhesive composition, and the content of the block copolymer (b) is preferably 55 to 85% by weight, more preferably 60 to 80% by weight.

In the present invention, the content [ b ] of the block copolymer (b) constituting the block copolymer composition (a) more preferably satisfies the following formula from the viewpoint of further improving the productivity and blocking resistance of the obtained block copolymer composition and the adhesive properties such as the holding power property and adhesiveness of the obtained adhesive composition.

5[S]-175≤[b]≤5[S]-130

([ S ] is the content of all monoalkenyl aromatic compounds in the block copolymer composition (A))

The peak molecular weight of the block copolymer (a) is 60,000 or more in terms of standard polystyrene from the viewpoint of the rubber elasticity property and mechanical strength of the obtained block copolymer (a) and the holding power performance of the obtained adhesive composition, and 110,000 or less in terms of standard polystyrene from the viewpoint of the melt viscosity, heat resistance, dispersibility and processability of the obtained adhesive composition. The preferable range is 65,000 to 105,000.

The peak molecular weight of the polymer block composed mainly of a monoalkenyl aromatic compound and constituting the block copolymer composition is 10,000 or more from the viewpoint of the holding power performance of the resulting adhesive composition, and 30,000 or less from the viewpoint of the adhesive performance and the melt viscosity at low temperatures. The preferable range is 10,000 to 25,000, and more preferably 12,000 to 23,000.

The molecular weight distribution of the polymer block mainly composed of a monoalkenyl aromatic compound constituting the block copolymer composition is 1.0 to 1.6 from the viewpoint of blocking resistance and adhesive force and holding force performance of the resulting adhesive composition. More preferably 1.0 to 1.3, and still more preferably 1.0 to 1.2.

The vinyl bond content of the conjugated diene portion of the block copolymer composition of the present invention is less than 20% from the viewpoint of heat resistance, that is, change in melt viscosity upon heating and discoloration upon heating. A more preferred range is less than 18%, and a still more preferred range is less than 16%.

The viscosity of the 15% toluene solution at 25 ℃ of the block copolymer composition (a) of the present invention is 10cP or more from the viewpoint of adhesive properties such as adhesive force and holding power of the obtained adhesive composition, and is 40cP or less from the viewpoint of melt viscosity, processability and heat resistance of the obtained adhesive composition. The viscosity of a 15% toluene solution at 25 ℃ is preferably 12-35 cP, and more preferably 15-32 cP.

The block copolymer composition (a) comprising the block copolymers (a) and (b) of the present invention can be obtained by polymerizing two styrene butadiene block copolymers (a) and (b) separately and mixing them by a method of polymerizing styrene in an inert hydrocarbon solvent using an organolithium compound as a polymerization initiator, then polymerizing the resulting polymer with butadiene, and then repeating the above operation as the case may be. In this case, the molecular weight is adjusted by controlling the amount of the organolithium compound. The composition (a) can be obtained by mixing the components after the completion of the polymerization reaction and deactivating the active material by adding water, alcohol, acid or the like, or by mixing the solutions of the block copolymers (a) and (b) after the completion of the polymerization reaction and deactivating the solutions, and then separating the polymerization solvent by, for example, stripping the mixed solution and drying the separated solution. The composition (a) may be obtained by mixing polymers obtained by separating the polymerization solvent from the solutions of the block copolymers (a) and (b) and drying the separated polymers with a roll or the like.

The block copolymer composition (A) comprising the block copolymers (a) and (b) of the present invention can be obtained by a method different from the above-mentioned method, that is, after the component (b) is polymerized by the same method as the above-mentioned method, a desired composition can be obtained in the same reaction system by adding an appropriate coupling agent to a polymerization system in a predetermined amount relative to the organolithium compound, and the resulting copolymer product is the component (a).

In the block copolymer constituting the present invention, a part or all of the unsaturated double bonds derived from the conjugated diene may be hydrogenated. The hydrogenation method is not particularly limited, and a known technique can be used.

As the inert hydrocarbon solvent used in the present invention, aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, isooctane and the like, alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane and the like, and aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene and the like can be used. These solvents may be used alone or in combination of two or more.

Examples of the organolithium compound used in the present invention include known compounds such as ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, phenyllithium, propenyllithium, and hexyllithium. Among them, n-butyllithium and sec-butyllithium are preferable. The organic lithium compound may be used alone or in combination of two or more. The amount used may be selected within a range that gives a desired peak molecular weight.

In the block copolymers (a) and (b), when the polymer block mainly composed of the conjugated diene compound is a random copolymer block of a monoalkenyl aromatic compound and a conjugated diene compound, for example, a method of polymerizing a monoalkenyl aromatic compound and then simultaneously adding a monoalkenyl aromatic compound and a conjugated diene compound, or a method of simultaneously polymerizing a part of a monoalkenyl aromatic compound and a conjugated diene compound and then adding a conjugated diene compound may be used. In addition, a polar compound may be added before starting the polymerization and/or during the polymerization reaction to adjust the chain distribution of the monoalkenyl aromatic compound. As the polar compound, for example, ethers or tertiary amines can be used, and specifically, one or a mixture of two or more selected from ethylene glycol dimethyl ether, tetrahydrofuran, α -methoxytetrahydrofuran, N' -tetramethylethylenediamine, and the like can be used. In addition, alkali metal tertiary alkoxides may also be used. Examples of the alkali metal tertiary alkoxide include potassium tert-butoxide, potassium tert-amylate, sodium amylate, and potassium isoamylate.

In addition, in order to adjust the vinyl bond amount of the conjugated diene compound in the block copolymers (a) and (b), for example, ethers and tertiary amines can be used, specifically, one or a mixture of two or more selected from ethylene glycol dimethyl ether, tetrahydrofuran, α -methoxytetrahydrofuran, N' -tetramethylethylenediamine and the like can be used, and particularly when high heat resistance is required, the vinyl bond amount is preferably less than 20%.

When the block copolymer (a) constituting the present invention is obtained by the coupling reaction of the block copolymer (b), examples of the coupling agent include bifunctional epoxy compounds, alkoxy silicon compounds such as dimethyldimethoxysilane, dimethyldiethoxysilane, trimethoxymethylsilane, triethoxysilane, tetramethoxysilane, tetraethoxysilane, ester compounds such as methyl benzoate, ethyl benzoate, vinyl aromatic hydrocarbons such as divinylbenzene, halogenated silicon compounds such as dichlorodimethylsilane, methylphenyldichlorosilane, tin compounds such as dimethyltin dichloride, tin tetrachloride, and silicon compounds such as tetrachlorosilane. Among them, bifunctional coupling agents are preferably used from the viewpoint of adhesive performance, and non-halogen coupling agents are preferably used from the viewpoint of heat discoloration of the adhesive composition.

In the block copolymer constituting the present invention, the coupling agent compound may be used alone or in a mixture of 2 or more.

The component (B) that can be used in the adhesive composition of the present invention can be variously selected depending on the application and required performance of the obtained adhesive composition, and for example, known tackifier resins such as coumarone-based resin, aromatic hydrocarbon resin, rosin-based resin, terpene-based resin, petroleum resin, phenol resin, terpene-phenol resin, alicyclic hydrocarbon resin, hydrogenated terpene-based resin, and hydrogenated rosin-based resin may be used in combination of 2 or more of these tackifier resins.

The amount of the tackifier resin of the present invention is 20 to 600 parts by weight, preferably 50 to 400 parts by weight, based on 100 parts by weight of the block copolymer, from the viewpoint of tackiness, adhesive force and holding power performance of the resulting adhesive composition.

In the composition of the present invention, a softener (component (C)) may be used. The type of the softening agent is not particularly limited, and known paraffinic or naphthenic process oils and mixed oils thereof can be used. When the color tone of the adhesive composition is emphasized, an alkane oil is more preferable.

The amount of the adhesive composition used is in the range of 0 to 300 parts by weight from the viewpoint of the retention property of the adhesive composition and the appearance of oil bleeding.

The adhesive composition of the present invention may contain an antioxidant as needed, and further improvement of thermal stability and resistance to discoloration by heat can be considered. Examples of the antioxidant include 2, 4-bis (n-octylthiomethyl) -O-cresol, 2, 4-bis (n-dodecylthiomethyl) -O-cresol, 2, 4-bis (phenylthiomethyl) -3-methyl-6-tert-butylphenol, n-octadecyl-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) propionate, 2 ' -methylene-bis (4-ethyl-6-tert-butylphenol), tetrakis [ methylene-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) propionate ] -methane, 1, 3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, and mixtures thereof, 2, 6-di-tert-butyl-4-methylphenol, 2, 6-di-tert-butyl-4-ethylphenol, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate, 2, 4-di-tert-pentyl-6- [1- (3, 5-di-tert-pentyl-2-hydroxyphenyl) ethyl ] phenylacrylate, 2- [1- (2-hydroxy-3, 5-di-tert-pentylphenyl) ethyl) -4, 6-di-tert-pentylphenylacrylate, 3, 9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionyloxy ] -1, hindered phenol compounds such as 1-dimethylethyl-2, 4, 8, 10-tetraoxaspiro [5, 5] undecane, sulfur compounds such as pentaerythritol-tetrakis (. beta. -laurylthiopropionate), dilauryl 3, 3 ' -thiodipropionate, dimyristyl 3, 3 ' -thiodipropionate, distearyl 3, 3 ' -thiodipropionate, phosphorus compounds such as tris (nonylphenyl) phosphite, cyclic neopentanetetraylbis (octadecyl phosphite), and tris (2, 4-di-t-butylphenyl) phosphite, and the like. These may be used alone or in combination of two or more. The amount of the addition is optional depending on the application, and is preferably 5 parts by weight or less based on 100 parts by weight of the adhesive composition.

Further, a light stabilizer may be used in the adhesive composition of the present invention. Examples of the light stabilizer include benzotriazole compounds such as 2- (2 '-hydroxy-5' -methylphenyl) benzotriazole, 2- (2 '-hydroxy-5' -tert-octylphenyl) benzotriazole, 2- (2 '-hydroxy-3', 5 '-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2' -hydroxy-3 '-tert-butyl-5' -methylphenyl) -5-chlorobenzotriazole and the like, bis (2, 2, 6, 6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2, hindered amine compounds such as 2, 6, 6-tetramethylpiperidine polycondensates and poly [ (6- (1, 1, 3, 3-tetramethylpropyl) imino-1, 3, 5-triazine-2, 4-diyl) [2, 2, 6, 6-tetramethyl-4-piperidyl ] imino ] hexamethylene [ [2, 2, 6, 6-tetramethyl-4-piperidyl ] imino ] and benzophenone compounds such as 2-hydroxy-4-methoxybenzophenone compounds.

By combining the above-mentioned benzotriazole-based compound or hindered amine-based compound, benzophenone-based compound, etc. with the composition of the present invention, the light resistance thereof can be further improved.

In addition to the above-mentioned stabilizers, pigments such as iron oxide and titanium dioxide, waxes such as paraffin wax, microcrystalline wax and low molecular weight polyethylene wax, polyolefins such as amorphous polyolefin and ethylene-ethyl acrylate copolymer, low molecular weight vinyl aromatic thermoplastic resin, natural rubber, polyisoprene rubber and polybutadiene rubber, synthetic rubbers such as styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, isoprene-isobutylene rubber, polycyclopentene rubber, styrene-butadiene block copolymers other than those of the present invention, styrene-isoprene block copolymers, hydrogenated styrene-butadiene block copolymers, and hydrogenated styrene-isoprene block copolymers.

The adhesive composition of the present invention can be prepared by a mixing method under heating conditions using a known mixer, kneader, or the like.

Examples

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The following methods were used for the various measurements.

(A) Analysis of Block copolymer

A-1) Total styrene content of Block copolymer:

the absorbance at 262nm was calculated by using an ultraviolet spectrophotometer (Hitachi UV 200).

A-2) vinyl bond content of butadiene moiety:

the measurement was carried out using an infrared spectrophotometer (model 1710 manufactured by Perkin Elmer) by the Hanpton method (described in Analytical chem., 21, 943 (' 43)).

A-3) peak molecular weight of block copolymer and composition ratio of block copolymer (a) and block copolymer (b):

the peak molecular weight and the composition ratio of the block copolymer were determined by GPC (apparatus manufactured by Waters, column combination using three MINIMIX. solvent manufactured by Polymer laboratories, tetrahydrofuran, measurement conditions of 35 ℃ temperature, 0.4 ml/min flow rate, 0.1 wt% sample concentration, and 40 μm injection). The peak molecular weight was determined from the following standard polystyrene (1.54X 10 manufactured by Waters Co.)⁶、4.1×10⁵、1.10×10⁵、3.5×10⁴、8.5×10³、1.8×10³) The scaled value obtained from the calibration curve of (1).

A-4) peak molecular weight of styrene Block Polymer and Mw/Mn:

the styrene Polymer block obtained by oxidative decomposition using osmium tetroxide and tert-butyl hydroperoxide (journal of Polymer Science, volume 1, page 429 (1946)) was measured by GPC (Shodex-K803, K802, K801, a column manufactured by Showa Denko K.K., a combination of devices and solvents, chloroform, under the conditions of 35 ℃ temperature, 1.0 ml/min flow rate, 0.05 wt% sample concentration and 100. mu.m injection amount).

A-5) viscosity of 15% toluene solution:

the viscosity of the 15% toluene solution was measured in a thermostatic bath maintained at 25 ℃ using a Cannon-Fenske viscosity tube.

A-6) blocking resistance:

a polyvinyl chloride pipe having a diameter of 75mm was filled with 300g of the polymer composition to which 1000ppm of ethylene bis stearamide was added, a load of 3kg was applied, the pipe was left at 50 ℃ for 24 hours, then the load was removed, the pipe was allowed to stand at room temperature for 1 hour, and then the polyvinyl chloride pipe was removed. Then, the cylindrical sample was compressed at a rate of 500 mm/min using a TENSILON-UTM-III tensile tester (manufactured by Toyo tester Co.) and the load at break was measured.

(B) Measurement of physical Properties of adhesive composition

The adhesive composition was taken out in a molten state, coated on a polyester film with an applicator to a thickness of 50 μm to prepare an adhesive tape sample, and the tackiness, adhesive force and holding force thereof were measured by the following methods.

B-1) Ring tack

Using a ring-shaped specimen having a length of 250mm X a width of 15mm, in terms of contact area with a PE plate: 15mm × 50mm, adhesion time 3 seconds, adhesion and peeling speed: the measurement was carried out at 500 mm/min.

B-2) adhesive force:

a specimen having a width of 25mm was attached to a polyethylene sheet, and the peel force at 180 ℃ was measured at a peel speed of 300 mm/min.

B-3) holding power:

the holding force was measured by applying a tape to a stainless steel plate and a PE plate so that the contact area was 25 mm. times.25 mm, applying a load of 1kg at 60 ℃ and measuring the time until the tape was peeled off.

B-4) resistance to thermal discoloration of the adhesive composition:

regarding the heat discoloration resistance of the adhesive composition, the color tone after heating for the time shown in Table 1 was examined by placing it in an oven at 180 ℃.

B-5) melt viscosity of adhesive composition:

the melt viscosity of the adhesive composition was measured by a Brookfield type viscometer at the temperature as shown in table 1.

B-6) Heat resistance (melt viscosity Change) of the adhesive composition:

the adhesive composition was placed in an oven at 180 ℃ for the times shown in table 1, and the melt viscosity was measured.

Example 1

The block copolymer used in the examples of the present invention was produced as follows.

After a 40L stainless steel reactor equipped with a jacket and a stirrer was sufficiently replaced with nitrogen, 17,600g of cyclohexane, 4.8g of tetrahydrofuran and 1470g of styrene were charged, warm water was introduced into the jacket, and the temperature of the contents was set to about 55 ℃. Thereafter, an n-butyllithium cyclohexane solution (pure component: 5.5g) was added to start the polymerization of styrene. After styrene was almost completely polymerized for 3 minutes, 1730g of butadiene (1, 3-butadiene) was added to continue the polymerization, and after butadiene was almost completely polymerized and the maximum temperature reached about 90 ℃ for 4 minutes, 0.33 equivalent of a diglycidyl ether compound of bisphenol as a coupling agent was added to n-butyllithium to cause a coupling reaction. Immediately after the addition of styrene, continuous stirring was carried out in the system using a stirrer.

The resulting block copolymer solution was taken out, 20g of water was added thereto and stirred, then 3.2g of n-octadecyl 3- (3 ', 5 ' -di-t-butyl-4 ' -hydroxyphenyl) propionate and 1.0g of 2, 4-bis (n-octylthiomethylene) -O-cresol were added, and the resulting solution was subjected to stripping, thereby removing the solvent to obtain an aqueous fraction. The splits were then dewatered and dried using hot rolls to give block copolymer composition samples.

100g of the thus-obtained block copolymer composition, 250g of an alicyclic saturated hydrocarbon resin ARCON M100 (trade name, manufactured by Mitsukawa chemical Co., Ltd.) as a tackifying resin, 60g of Diana Process Oil PW-90 (trade name, manufactured by Shikino chemical Co., Ltd.) as a softening agent, and 1g of Sumilizer GM (trade name, manufactured by Sumitomo chemical Co., Ltd.) as a heat stabilizer were mixed, and the mixture was melt-kneaded at 180 ℃ for 2 hours in a 1L vessel equipped with a stirrer to obtain a hot melt adhesive composition.

Example 2

Polymerization was carried out in the same manner as in example 1 except that the amounts of charged styrene and butadiene (1, 3-butadiene) and the amount of the n-butyllithium cyclohexane solution were changed to obtain a block copolymer polymer solution, butadiene was almost completely polymerized and the maximum temperature was reached for 4 minutes, and then 0.28 equivalent of dimethoxydimethylsilane as a coupling agent was added to the obtained solution to cause a coupling reaction. At this time, the system was continuously stirred by a stirrer. The obtained block copolymer solution was subjected to solvent removal and drying in the same manner as in example 1 to obtain a block copolymer composition, and mixed in the same manner as in example 1 to obtain a hot melt adhesive composition.

Example 3

After a 40L stainless steel reactor equipped with a jacket and a stirrer was sufficiently replaced with nitrogen, 17,600g of cyclohexane, 4.8g of tetrahydrofuran, and 685g of styrene were added, warm water was introduced into the jacket, and the temperature of the contents was set to about 55 ℃. Thereafter, an n-butyllithium cyclohexane solution (pure component: 2.9g) was added to start the polymerization of styrene. After styrene was almost completely polymerized for 3 minutes, 1830g of butadiene (1, 3-butadiene) was added to continue the polymerization, and after butadiene was almost completely polymerized for 4 minutes, 685g of styrene was added to complete the polymerization, thereby obtaining a block copolymer (a). At this time, the system was continuously stirred by a stirrer. The resulting block copolymer (a) solution was taken out, 20g of water was added thereto, the mixture was stirred, and then 3.2g of n-octadecyl-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) propionate and 1.0g of 2, 4-bis (n-octylthiomethyl) -O-cresol were added. Further, after a 40L stainless steel reactor equipped with a jacket and a stirrer was sufficiently replaced with nitrogen, 17,600g of cyclohexane, 4.8g of tetrahydrofuran, and 1370g of styrene were charged, warm water was introduced into the jacket, and the temperature of the contents was set to about 55 ℃. Thereafter, an n-butyllithium cyclohexane solution (pure component: 5.8g) was added to the solution to start polymerization of styrene. After styrene was almost completely polymerized for 3 minutes, 1830g of butadiene (1, 3-butadiene) was added to complete the polymerization, thereby obtaining a block copolymer (b). At this time, the system was continuously stirred by a stirrer. The resulting solution of the block copolymer (b) was taken out, 20g of water was added thereto, the mixture was stirred, and then 3.2g of n-octadecyl-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) propionate and 1.0g of 2, 4-bis (n-octylthiomethyl) -O-cresol were added.

Next, the block copolymer solution (a) and the block copolymer solution (b) were mixed at a ratio of 33/67. The solvent was removed from the obtained block copolymer composition solution in the same manner as in example 1, followed by drying to obtain a block copolymer composition, which was then mixed in the same manner as in example 1 to obtain a hot melt adhesive composition.

Comparative example 1

A block copolymer polymer solution was obtained by polymerization in the same manner as in example 1 except that the amounts of charged styrene and butadiene (1, 3-butadiene) and the amount of the n-butyllithium cyclohexane solution were changed, and after butadiene was almost completely polymerized to the maximum temperature for 4 minutes, 0.35 equivalent of dimethoxydimethylsilane as a coupling agent to n-butyllithium was added to the obtained solution to cause a coupling reaction with the obtained solution. Immediately after the addition of styrene, continuous stirring was carried out in the system by a stirrer. The obtained block copolymer solution was subjected to solvent removal and drying in the same manner as in example 1 to obtain a block copolymer composition, and mixed in the same manner as in example 1 to obtain a hot melt adhesive composition.

Comparative example 2

A block copolymer polymer solution was obtained by polymerization in the same manner as in example 1 except that the amounts of charged styrene and butadiene (1, 3-butadiene) and the amount of the n-butyllithium cyclohexane solution were changed, and after butadiene was almost completely polymerized to the maximum temperature for 4 minutes, 0.64 equivalents of a bisphenol-based diglycidyl ether compound as a coupling agent was added to the obtained solution to cause a coupling reaction. At this time, the system was continuously stirred by a stirrer. The obtained block copolymer solution was subjected to solvent removal and drying in the same manner as in example 1 to obtain a block copolymer composition, and mixed in the same manner as in example 1 to obtain a hot melt adhesive composition.

Comparative example 3

A40L stainless steel reactor equipped with a jacket and a stirrer was sufficiently substituted with nitrogen, 17,600g of cyclohexane, 4.8g of tetrahydrofuran and 970g of styrene were added, warm water was passed through the jacket, the temperature of the contents was set to about 55 ℃, then an n-butyllithium cyclohexane solution (pure component: 6.7g) was added to start the polymerization of styrene, after the polymerization of styrene was almost completed for 3 minutes, butadiene (1, 3-butadiene) 1890g and styrene 240g were added to continue the polymerization, after the polymerization reached the maximum temperature almost completed for 4 minutes, dimethoxydimethylsilane 0.27 equivalent as a coupling agent was added to n-butyllithium to cause a coupling reaction, and at this time, the system was continuously stirred with a stirrer, the solvent was removed from the resulting solution of the block copolymer by the same method as in example 1, and the block copolymer composition was dried, a hot melt adhesive composition was obtained by mixing the components in the same manner as in example 1.

Comparative example 4

A block copolymer polymer solution was obtained by polymerization in the same manner as in example 1 except that the amounts of charged styrene and butadiene (1, 3-butadiene) and the amount of the n-butyllithium cyclohexane solution were changed, and after butadiene was almost completely polymerized to the maximum temperature for 4 minutes, 0.23 equivalents of a bisphenol-based diglycidyl ether compound was added to the obtained solution as a coupling agent to cause a coupling reaction. At this time, the system was continuously stirred by a stirrer. The obtained block copolymer solution was subjected to solvent removal and drying in the same manner as in example 1 to obtain a block copolymer composition, and mixed in the same manner as in example 1 to obtain a hot melt adhesive composition.

Comparative example 5

After a 40L stainless steel reactor equipped with a jacket and a stirrer was sufficiently replaced with nitrogen, 17,600g of cyclohexane, 4.8g of tetrahydrofuran, 1.66g of N, N, N' -tetramethylethylenediamine, and 1340g of styrene were added, warm water was introduced into the jacket, and the temperature of the contents was set to about 55 ℃. Thereafter, an n-butyllithium cyclohexane solution (pure component: 5.1g) was added to start the polymerization of styrene. After styrene was almost completely polymerized for 3 minutes, 1860g of butadiene (1, 3-butadiene) was added to continue the polymerization, and after butadiene was almost completely polymerized and the maximum temperature was reached at about 90 ℃ for 4 minutes, 0.33 equivalent of a diglycidyl ether compound of bisphenol as a coupling agent was added to n-butyllithium to cause a coupling reaction. Immediately after the addition of styrene, continuous stirring was carried out in the system by a stirrer. The obtained block copolymer solution was subjected to solvent removal and drying in the same manner as in example 1 to obtain a block copolymer composition, and mixed in the same manner as in example 1 to obtain a hot melt adhesive composition.

Reference example

A block copolymer polymer solution was obtained by polymerization in the same manner as in example 1 except that the amounts of charged styrene and butadiene (1, 3-butadiene) and the amount of the n-butyllithium cyclohexane solution were changed, and after butadiene was almost completely polymerized to the maximum temperature for 4 minutes, 0.4 equivalent of dimethyldichlorosilane as a coupling agent was added to the obtained solution to cause a coupling reaction. At this time, the system was continuously stirred by a stirrer. The obtained block copolymer solution was subjected to solvent removal and drying in the same manner as in example 1 to obtain a block copolymer composition, and mixed in the same manner as in example 1 to obtain a hot melt adhesive composition.

The structures of the respective block copolymer compositions obtained and the physical properties of the adhesive compositions containing them are shown in table 1. In the present invention, by using a block copolymer composition having a predetermined specific structure and excellent in handling properties, an adhesive composition having a low melt viscosity, excellent in low-temperature processability, particularly excellent in balance between adhesive properties and holding power, and extremely excellent in heat resistance can be obtained.

1 and 2 of the following structural formula were mixed in a ratio of 1: 1.

The present invention is described in detail with reference to specific embodiments, and it is apparent to those skilled in the art that various changes and modifications can be applied without departing from the spirit of the present invention.

This application is based on Japanese patent application No. 2/7/2003 (Japanese patent application No. 2003-030484), the contents of which are incorporated herein by reference.

Industrial applicability

According to the present invention, an adhesive composition can be provided which solves the problems of the conventional adhesive compositions, is particularly easy to process at low temperatures, and has extremely excellent appearance, adhesive performance and heat resistance.

Claims (10)

1. An adhesive composition comprising (A) a block copolymer composition, (B) a tackifier resin and (C) a softener, wherein the amount of the tackifier resin (B) is 20 to 600 parts by weight based on 100 parts by weight of the block copolymer composition (A),

the block copolymer composition (A) comprises a block copolymer (a) and a block copolymer (b), wherein the block copolymer (a) comprises at least two polymer blocks mainly comprising a monoalkenyl aromatic compound and at least one polymer block mainly comprising a conjugated diene; the block copolymer (b) comprises at least one polymer block mainly comprising a monoalkenyl aromatic compound and at least one polymer block mainly comprising a conjugated diene,

the peak molecular weight of the block copolymer (a) measured by GPC is 6 to 11 ten thousand in terms of standard polystyrene,

the peak molecular weight of the polymer block mainly composed of a monoalkenyl aromatic compound constituting the block copolymer composition (A) is 1 to 3 ten thousand, the molecular weight distribution Mw/Mn is 1.0 to 1.6,

the block copolymer composition (A) having a total monoalkenyl aromatic compound content of more than 40% by weight to not more than 50% by weight,

the block copolymer composition (A) contains 50 to 90 wt% of a block copolymer (b),

in the block copolymer composition (A), the vinyl bond content of the conjugated diene portion is less than 20%,

the block copolymer composition (A) has a 15% toluene solution viscosity of 10 to 40cP at 25 ℃.

2. The adhesive composition according to claim 1, wherein the content of the block copolymer (b) in the block copolymer composition (A) is 55 to 85% by weight.

3. The adhesive composition according to claim 1, wherein the content of the block copolymer (b) in the block copolymer composition (A) is 60 to 80% by weight.

4. The adhesive composition according to any one of claims 1 to 3, wherein the molecular weight distribution Mw/Mn of the polymer block based on a monoalkenyl aromatic compound constituting the block copolymer composition (A) is from 1.0 to 1.2.

5. The adhesive composition according to any one of claims 1 to 3, wherein the block copolymer (a) is a block copolymer obtained by a coupling reaction of the block copolymer (b) with a non-halogen type coupling agent.

6. The adhesive composition according to claim 4, wherein the block copolymer (a) is a block copolymer obtained by a coupling reaction with the block copolymer (b) using a non-halogen type coupling agent.

7. The adhesive composition according to any one of claims 1 to 3, wherein the conjugated diene compound is butadiene.

8. The adhesive composition of claim 4, wherein the conjugated diene compound is butadiene.

9. The adhesive composition of claim 5, wherein the conjugated diene compound is butadiene.

10. An adhesive composition comprising (B) 20 to 600 parts by weight of a tackifier resin and (C) 0 to 300 parts by weight of a softener per 100 parts by weight of a block copolymer composition (A),

the block copolymer composition (A) comprises a block copolymer (a) and a block copolymer (b), wherein the block copolymer (a) comprises at least two polymer blocks mainly comprising a monoalkenyl aromatic compound and at least one polymer block mainly comprising a conjugated diene; the block copolymer (b) comprises at least one polymer block mainly comprising a monoalkenyl aromatic compound and at least one polymer block mainly comprising a conjugated diene,

the peak molecular weight of the block copolymer (a) measured by GPC is 6 to 11 ten thousand in terms of standard polystyrene,

the peak molecular weight of the polymer block mainly composed of a monoalkenyl aromatic compound constituting the block copolymer composition (A) is 1 to 3 ten thousand, the molecular weight distribution Mw/Mn is 1.0 to 1.6,

the block copolymer composition (A) having a total monoalkenyl aromatic compound content of more than 40% by weight to not more than 50% by weight,

the block copolymer composition (A) contains 50 to 90 wt% of a block copolymer (b),

in the block copolymer composition (A), the vinyl bond content of the conjugated diene portion is less than 20%,

the block copolymer composition (A) has a 15% toluene solution viscosity of 10 to 40cP at 25 ℃.