JP2806875B2 - Hot melt adhesive composition and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an excellent adhesive strength to polyolefin resins widely used in various industries and can be applied at a low use temperature, so that the heat stability can be improved. And to a hot melt adhesive composition which is extremely excellent in

[0002]

2. Description of the Related Art Various molded products of polyolefin resin are:
Absorbents such as disposable diapers, sanitary napkins, absorbent pads, etc., as leak-proof sheets for disposable items, and polypropylene labels, polypropylene cardboard, video cassette cases, book cases, food and cosmetic outer cases, and electrical parts, automobiles Widely used in the field of so-called product assembly of parts. When these polyolefin resins are molded and then compounded with other materials, conventionally, styrene-butadiene-styrene (hereinafter referred to as S
Displayed as BS. ), A hot melt adhesive based on a thermoplastic copolymer such as styrene-isoprene-styrene (hereinafter referred to as SIS) is used.

[0003] In particular, in the bonding of liquid absorbent articles,
JP-A-60-158284 discloses a hot melt adhesive using SBS and its hydrogenated styrene-ethylene-butylene-styrene (hereinafter referred to as SEBS). Also, Japanese Patent Application Laid-Open No. Sho 62-7776
Japanese Patent Application Laid-Open Publication No. H11-163,086 discloses a hot melt adhesive obtained by adding an ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) to the above SBS and SIS. Although the hot-melt adhesives disclosed in these publications have a sufficient adhesive force to a polyolefin film, they have a serious drawback in thermal stability. Therefore, hot melt adhesives using SBS and SIS as hydrogenated SEBS and SEPS as base polymers have been proposed, but these adhesives have insufficient adhesive strength.

[0004]

As described above, the SIS
The hot-melt adhesive based on has been used for bonding various adherends, particularly for polyolefin resins, due to its excellent adhesiveness, but has a problem in terms of thermal stability. It has been known that when such an SIS-based hot melt adhesive is used at a low temperature, the thermal stability is remarkably improved. However, since the melt viscosity increases, there is a problem in coatability.

In general, a low-molecular weight polymer is used as a base to obtain a hot-melt adhesive having a low viscosity. However, since the low-molecular-weight polymer serving as a base has a viscosity different from that of a high-molecular-weight polymer, it is difficult to wash it after synthesis. In addition, there is a problem that even during the production of a hot melt adhesive, it cannot be formed into pellets due to its viscosity, and handling is difficult. In order to reduce the viscosity of a base polymer synthesized in a molecular weight range that can be manufactured by ordinary manufacturing equipment as an adhesive composition, an H-Sf-H type triblock SIS copolymer is converted to an H-Sf type triblock SIS copolymer. A method of mixing a diblock SI (styrene-isoprene) copolymer is also being studied, but there is a problem that a strong styrene domain is not formed in the hot-melt adhesive according to this method, resulting in a decrease in cohesive strength. .

As another measure for reducing the viscosity of a base polymer synthesized in a molecular weight range that can be produced by ordinary production equipment as an adhesive composition, it is conceivable to use a large amount of a softening agent. However, in liquid absorbent disposable articles such as disposable diapers, sanitary napkins and absorbent pads, a breathable polyolefin sheet is often used in order to reduce so-called "humidity". In this case, the softening of the hot melt adhesive is performed. When the content ratio of the agent component is large, the softener migrates to the porous gas-permeable polyolefin, which causes not only the appearance of dirt but also a change in the adhesive strength of the hot melt adhesive. Therefore, a hot-melt adhesive having a reduced softening agent is required as much as possible. However, if the amount of the oil as the softening agent is reduced, the viscosity of the composition increases, and the application work at low temperatures becomes difficult, which is not satisfactory.

Further, when the use temperature of the adhesive is high, a thin polyolefin film is deformed by heat, and therefore a hot melt adhesive which can be applied at a low use temperature is desired.

[0008]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present invention has been developed by using a high molecular weight thermoplastic elastomer which can be easily produced using conventional production equipment as it is, as a base polymer. This polymer is dissociated by compounding a small amount of acid during compounding of various additives, and a thermoplastic block copolymer containing a triblock structure is formed even after dissociation. An adhesive composition was found and completed.

The present invention is a hot melt adhesive composition comprising (A) a thermoplastic block copolymer, (B) a tackifier, (C) a stabilizer, and (D) a softener, The component (A) is produced by dissociation of a high molecular weight block copolymer used as a raw material with an acidic substance,
H-Sf-H type (H is a hard segment, Sf
Indicates a soft segment. ), The retention rate of tensile strength after dissociation is 50% or more of the high molecular weight block copolymer before dissociation, and the solution viscosity of a 25% by weight toluene solution at 25 ° C is 150 cps or less. It is a hot melt adhesive composition characterized by that
The present invention is characterized in that a high-molecular-weight block copolymer which produces a thermoplastic block copolymer (A) having the above properties is used as a raw material.

The high molecular weight block copolymer is a non-viscous solid before being dissociated by an acidic substance, and can be produced by conventional synthesis equipment without causing a washing problem. It is easy to handle even in the manufacturing process, and provides a hot melt adhesive that can be applied at a low temperature by lowering the melt viscosity by dissociation using an acidic substance at the time of manufacturing the adhesive.

In particular, the high-molecular-weight block copolymer used as a raw material in the present invention is such that a thermoplastic block copolymer formed by dissociation with an acidic substance still remains after dissociation.
It has an H-Sf-H type triblock structure in its molecule, and its melt viscosity is reduced, but it is characterized in that it can exhibit physical properties derived from the triblock after cooling. The dissociation of the raw material high molecular weight block copolymer is physically 10
The thermoplastic block copolymer (A) containing the undissociated high molecular weight block copolymer may have the above-mentioned properties. In particular, a polymer containing an H-Sf-H type triblock structure in the molecule has a retention rate of 50% of the tensile strength of the original high molecular weight block copolymer.
It is necessary that the above-mentioned maintenance rate is 60%
The above are preferred. Due to the presence of the H-Sf-H type triblock structure, a high retention rate of physical properties can be achieved. When the maintenance ratio of the physical properties represented by the tensile strength is 50% or less, the performance as an adhesive, particularly the holding power is reduced. A polymer containing a triblock structure formed by dissociation in a molecule does not need to have polystyrene styrene at both ends of the molecule, and a polymer containing another polystyrene unit in the molecule may be H-Sf-H-Sf. And the like.

In the present invention, the content of each of the components (A) to (E) in the hot melt adhesive composition is such that the component (A) is 10 to 60% by weight and the component (B) is
The component is 20 to 80% by weight, and the component (C) is 0.0% by weight.
5 to 5% by weight, and the component (D) is (A), (B), (C), or 100% by weight of the hot melt adhesive composition.
It is preferable that the remaining amount is obtained by subtracting the content ratio of each component. In particular, a hot-melt adhesive that can be applied at a low temperature even when the amount of the softener used is suppressed in order to prevent the migration of the softener in a product using the porous breathable polyolefin is obtained.

The thermoplastic block copolymer used as the component (A) in the present invention is preferably such that the hard segment H is polystyrene and the soft segment Sf is polyisoprene. Here, polystyrene and polyisoprene may be those obtained by copolymerizing other monomers as long as their properties are not impaired. Among these materials, SIS-based materials exhibit excellent characteristics and are preferred for adhesion.

In the step of producing the composition, the content of polystyrene in the thermoplastic block copolymer produced by dissociation with the acidic substance is 25 to 35% by weight in the thermoplastic block copolymer, and The viscosity of a 25% by weight toluene solution of the block copolymer (25
C) is preferably 135 cps or less in the hot melt adhesive composition of the present invention. In particular, the content of polystyrene in the thermoplastic block copolymer is preferably 30 to 35% by weight in the block copolymer. It is more preferable that the block copolymer has a 25% toluene solution viscosity (25 ° C.) of 100 cps or less. When the polystyrene content is 25% by weight or less,
If the cohesion is insufficient, and if it is 35% by weight or more, the flexibility is reduced. The viscosity of the toluene solution is a substitute for the melt viscosity of the polymer. When the solution viscosity is 135 cps or less, low-temperature coating becomes possible. Polystyrene content is 30-35
A thermoplastic block copolymer having a weight% and a toluene solution viscosity of 100 cps or less gives the most stable workability and characteristics. The lower limit of the solution viscosity is not particularly limited as long as the adhesive strength satisfies the requirement.

[0015] In the present invention, in addition to the component described in claim 1, the component (E) further comprises ethylene-
It is also preferable to add 5 to 25% by weight of at least one copolymer selected from a vinyl acetate copolymer, an ethylene-normal butyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-methyl acrylate copolymer. It is an aspect. This is for contributing to adjustment of wettability with an object to be bonded, improvement of adhesive strength, and the like.

In the present invention, the component (A) contains Sf-H
May be used in combination, and the diblock copolymer may be formed by dissociating a high molecular weight block copolymer with an acidic substance. Such a diblock copolymer has no effect on holding power,
It contributes to improvement of tack and adhesive strength. Accordingly, the thermoplastic block copolymer, which is a characteristic component of the present invention, can be denatured using such a die block copolymer as long as the retention rate of tensile strength of the thermoplastic block copolymer is not reduced to 50% or less.

The hot melt adhesive composition of the present invention is obtained by mixing a high molecular weight block copolymer as a raw material and an acidic substance.
Heating to dissociate the high molecular weight block copolymer,
Even after dissociation, a thermoplastic block copolymer containing an H-Sf-H type triblock structure in the molecule is used. At the time of this dissociation reaction or after the dissociation reaction, a tackifier, a stabilizer, a softener, etc. It is manufactured by adding and mixing predetermined components.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION
The high molecular weight block copolymer dissociated by an acidic substance refers to at least H-Sf-H obtained by solution polymerization.
H is a block copolymer having a high cohesive force, and Sf is a flexible soft segment. In particular, H is preferably an aromatic vinyl polymer, and Sf is preferably a conjugated diene polymer, and a copolymer having such a triblock structure is preferably used.
A high molecular weight block copolymer linked by a coupling agent that can be dissociated by an acidic substance is used as a raw material in the present invention. As the aromatic vinyl polymer as the H component, polystyrene is preferable, and a high molecular weight block copolymer having a content of 14 to 45% by weight can be used. Preferred polystyrene content is 20% by weight
-40% by weight, more preferably 25% by weight
35% by weight is used. As the conjugated diene-based polymer which is the Sf component, polysoprene and polybutadiene are used, and polyisoprene is preferable. The content of the H segment before and after dissociation is substantially the same.

The thermoplastic block copolymer (A) in the present invention can be used in an amount of from 10% by weight to 60% by weight in the hot melt adhesive composition. When the content is less than 10% by weight, no cohesive force is exhibited, and when it exceeds 60% by weight, the viscosity becomes too high, and it cannot be used at a low coating temperature.
The solution viscosity of the block copolymer is 25 after dissociation.
The viscosity of the hot melt adhesive is preferably 150 cps or less, and the melt viscosity of the hot melt adhesive becomes high, and the low coating temperature, which is the object of the present invention, is not achieved.

The block copolymer which dissociates with the acidic substance used in the present invention as long as the characteristics of the present invention are not impaired is replaced with another thermoplastic block copolymer, SB.
S, SIS, SEBS, SEPS, hydrogenated SBR (H
SBR), crystalline polyolefin-ethylene-butylene-crystalline polyolefin copolymer (CEBC), partially hydrogenated SBS, ethylene-vinyl acetate copolymer (EV
A), ethylene-n-butyl acrylate (EnBA)
It is possible to adjust various properties by adding an ethylene copolymer such as butyl rubber, EP rubber or the like as a raw material of the component (A). In this case, a composition in which a thermoplastic polymer having a higher molecular weight coexists in addition to the thermoplastic block copolymer generated by dissociation is obtained.

In the present invention, the acidic substance necessary for dissociation of the starting high molecular weight block copolymer includes aliphatic monocarboxylic acids such as stearic acid, oleic acid and palmitic acid, and dicarboxylic acids such as maleic acid and fumaric acid. , Aromatic monocarboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, aromatic dicarboxylic acids such as terephthalic acid, abietic acid, neoabietic acid, dihydroabietic acid,
Resin acids such as tetrahydroabietic acid, d-pimaric acid, dehydroabietic acid, and levopimaric acid can be used alone or as a mixture of two or more. In addition, a polar substance can be dissociated, and a highly polar tackifier such as rosin ester, rosin phenol, and terpene-phenol can also be used as a dissociating agent. The compounding amount of the acidic substance is 0.01 to 20% by weight, more preferably 0.1 to 10% by weight in the composition. 0.
If it is less than 01% by weight, there is not enough ability to dissociate,
If the content exceeds 0% by weight, poor heat stability of the acidic substance itself appears in the hot melt adhesive, which is not preferable.

Examples of the tackifier used as the component (B) in the present invention include natural rosin, modified rosin, hydrogenated rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, and pentaerythritol ester of natural rosin Pentaerythritol ester of modified rosin, pentaerythritol ester of hydrogenated rosin, copolymer of natural terpene and its hydrogenated derivative, polyterpene resin and phenolic modified terpene resin and its hydrogenated derivative, aliphatic petroleum hydrocarbon resin and its Examples include hydrogenated derivatives, aromatic petroleum hydrocarbon resins and hydrogenated derivatives thereof, cycloaliphatic petroleum hydrocarbon resins and hydrogenated derivatives thereof, and these can be used alone or in combination of two or more. Among the above tackifiers,
Hydrogenated derivatives such as resins are preferred because they have no odor and have good thermal stability.

When the hot melt adhesive of the present invention is used for sanitary articles such as sanitary napkins, the tackifier is preferably colorless or white and substantially odorless. In the present invention, “essentially odorless” means that there is almost no odor as shown in the voluntary regulations of the Japan Sanitary Material Manufacturers Association.

The mixing ratio of the tackifier is usually 20 to 80%, preferably 3 to 3%, based on the total amount of the hot melt adhesive.
0 to 70%. If the compounding amount is less than 20%, the tackiness of the hot melt adhesive decreases, and if it exceeds 70%, the hot melt adhesive becomes brittle and the low-temperature adhesiveness decreases.

In the present invention, the softener component used as the component (D) is compounded for the purpose of imparting flexibility of the hot melt adhesive, lowering the melt viscosity, adjusting the adhesive strength, and the like. Examples of the softener include a plasticizing oil, which is used for the purpose of lowering the melt viscosity of the hot melt adhesive and imparting flexibility. Examples of the plasticized oil include paraffinic oils, naphthenic oils, and aromatic oils. Among them, when used for sanitary materials, paraffinic oils that are colorless and substantially odorless are used. preferable. The mixing ratio of this plasticizing oil is
It is usually 30% by weight or less, preferably 5 to 25% by weight, based on the total amount of the hot melt adhesive. Within this range, the flexibility, the effect of lowering the viscosity and the like are good, the migration of the softener in the product using the porous gas-permeable polyolefin can be prevented, and a well-balanced adhesive can be obtained. Further, as the softener, liquid hydrocarbons can also be used, and examples thereof include liquid tackifiers, liquid polymers such as polybutene, polyisobutylene, polyisoprene, and polybutadiene, and the mixing ratio of these softeners. The content is usually 30% or less as in the case of the plasticizing oil.

Further, as the softening agent, waxes can be used, and are used for the purpose of lowering the melt viscosity of the hot melt adhesive and adjusting the adhesive strength. As these waxes,
Paraffin wax, microcrystalline wax,
Examples include synthetic wax by a Fischer-Tropsch method, low molecular weight polyethylene wax, oxidized wax, low molecular weight polypropylene wax, caster wax and the like. The above softeners can be used alone or in combination of two or more.

The stabilizer (C) used in the present invention is compounded in order to prevent the molecular weight of the hot melt adhesive from being lowered by heat, gelation, coloring and odor. Examples of the stabilizer include an antioxidant and an ultraviolet absorber. The ultraviolet absorber is used for removing fluorescence of a hot melt adhesive and improving light resistance. As the antioxidant and the ultraviolet absorber, any one can be used without particular limitation as long as it is used for hot-melt adhesives for general sanitary goods. For example, phenol-based antioxidants include Antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like, and examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. Can be These stabilizers can be used alone or in combination of two or more. The mixing ratio of the component (C) is 0.05 to 5 in the total amount of the hot melt adhesive composition.
% By weight, preferably 0.1 to 3.0% by weight. 0.
If the amount is less than 05% by weight, the desired effect of the stabilizer is not obtained. Conversely, if the amount exceeds 5% by weight, the effect corresponding to this is not obtained, which is disadvantageous in cost.

In the hot melt adhesive composition of the present invention, it is necessary to set a step or conditions for dissociating a raw material high molecular weight block copolymer with an acidic substance, as compared with a conventional method for producing a hot melt adhesive composition. However, as a heating and mixing device for the production, a device that can be used for producing a general hot melt adhesive composition can be used as it is. The acidic substance, the high molecular weight block copolymer,
And the other raw material components may be charged into a production apparatus, and heated and mixed to produce a composition.Also, the high molecular weight block copolymer is first kneaded with the acidic substance, heated and dissociated, and then mixed. May be mixed to produce a composition.

[0029] The hot melt adhesive of the present invention is used for bonding one member selected from the group consisting of woven fabric, nonwoven fabric, rubber, resin, paper, metal, wood, glass and plastic to a polyolefin resin or to a polyolefin resin. Is preferably used. The adhesive is melted, applied to at least one of the polyolefin film and the member, and then pressed against the film and the member. Examples of the coating method include a multi-bead coating method, a T-die coating method, and a roll coating method. In particular, a spray coating method can be used because of its low melt viscosity, and is preferred.

[0030]

According to the present invention, a triblock copolymer having a relatively low molecular weight can be obtained by heating in the presence of a small amount of an acidic substance in a hot-melt adhesive. A hot melt adhesive is obtained,
It becomes possible to use at low temperature, and it becomes a hot melt adhesive excellent in heat stability, workability and adhesiveness. Further, even when used for bonding of breathable polyethylene, there is no bleeding of oil, so that there is no appearance contamination.

[0031]

EXAMPLES Examples of the present invention will be described below together with comparative examples. [Raw Materials] The raw materials used in the examples of the present invention are as follows. (A) Thermoplastic high molecular weight block copolymer used as a raw material of component: Table 1 summarizes.

Examples of the acidic substance used as a component for decomposing the component (A), the tackifier used as the component (B), and the component (E): Table 2 shows the results.

[0033]

[Table 1]

[0034]

[Table 2]

Stabilizer used as component (C):-Sumilizer BP101: Antioxidant manufactured by Sumitomo Chemical Co., Ltd.-Sumilizer GM: Antioxidant manufactured by Sumitomo Chemical Co., Ltd.-Sumilizer TPD: Antioxidant manufactured by Sumitomo Chemical Co., Ltd.-JF- 77: UV absorber made by Johoku Chemical

(Examples 1 to 5, Comparative Examples 1 to 4) The following predetermined materials were blended at the ratio shown in Table 3 and melted and mixed at about 150 ° C. to produce a hot melt adhesive. For the production, a mixing device equipped with a heating jacket and a stirring device was used. All amounts are shown in parts by weight.

[0037]

[Table 3]

With respect to the hot melt adhesives of Examples 1 to 5 and Comparative Examples 1 to 4 obtained as described above, melt viscosity,
The properties of adhesion, holding power and thermal stability were examined. The results are shown in Table 4 below. The characteristics were evaluated by the following methods.

[Melt Viscosity] The hot melt adhesive was heated and melted, and the viscosity at 120 ° C. was measured with a Brookfield thermocell viscometer. When the result was 5000 cps or more, the temperature was increased by 10 ° C. and the measurement was performed again. In the following examples, the measurement was similarly performed until the value became 5000 cps or less.

[Adhesive Strength] A sheet prepared by applying a hot-melt adhesive with a thickness of 50 μm to a polyester (PET) film having a thickness of 50 μm and forming the sheet into a width of 2.5 cm was converted to a polyethylene (PE) having a thickness of 100 μm. The film was bonded at 20 ° C. and left at a temperature of 20 ° C. for one day. Thereafter, peeling was performed at a tensile speed of 300 mm / min, and the peel strength was defined as the adhesive strength.

[Holding power] A sheet was prepared by applying a hot melt adhesive with a thickness of 50 μm to a PET film having a thickness of 50 μm, and the sheet was formed into a 2.5 cm width to obtain a test piece. A 100 μm-thick PE film was bonded to the test body so that the adhesion area was 1.0 cm × 2.5 cm,
A 1 kg weight was applied vertically to the adhesive and left at 40 ° C. Then, the time required for the 1 kg weight to fall was measured, and this was defined as the holding force.

[Heat Stability] 30 g of the hot melt adhesive was placed in a 75 cc glass bottle, and the hot air circulating drier temperature was set to the coating temperature determined by the melt viscosity measurement, and left for 3 days and 7 days. After the treatment, the presence or absence of carbides and edge rings was visually evaluated. Thereafter, the hot melt adhesive was taken out, and the presence or absence of a gel was also evaluated. Further, the melt viscosity was measured by the above-described method, and the viscosity maintenance ratio after standing against the initial viscosity (before the heat treatment by the hot air circulation dryer) was calculated by the following formula. Viscosity maintenance rate = (V ₁ / V ₀ ) × 100 (%) V ₀ : initial (before treatment) viscosity V ₁ : viscosity after treatment

The results are summarized in Table 4. From Table 4,
All of the examples of the present invention have a melt viscosity of 5000 c at a low temperature.
ps or less, it is clear that low-temperature coating is possible, and the adhesive strength and holding power are both excellent. Furthermore, the coating temperature can be lowered, so that the thermal stability is naturally good.

[0044]

[Table 4]

In Table 5, similar experiments were carried out for Comparative Examples 4 to 7, and the formulations were shown in the upper row and the results in the lower row. In these results, Comparative Examples 4, 6, and 7 have relatively low 14
It can be seen that coating is possible at 0 ° C., but there is a problem with the holding power.

[0046]

[Table 5]

Example 6, Comparative Example 8 In Example 6, the hot-melt adhesive compounded in Example 4 was spray-coated on a breathable polyethylene sheet used for disposable diapers, and spunbond (Asahi Kasei) (Manufactured by Co., Ltd.).
In Comparative Example 8, the hot melt adhesive similarly blended in Comparative Example 1 was used, and bonding was performed in the same manner as in Example 6 above. The samples obtained in Example 6 and Comparative Example 8 were allowed to stand in a thermostat at 50 ° C. for one week, and the oil bleeding properties were compared. In Comparative Example 8, oil oozed out onto the breathable polyethylene sheet and a pattern emerged in a spray pattern.
No oil seepage was observed at all.

(Example 7, Comparative Example 9) In the same procedure as in Examples 1 to 5, a hot melt adhesive was prepared by the formulation shown in the upper part of Table 6 , and evaluated. The method of measuring the adhesive force and the holding force is the same as in Example 6.

[0049]

[Table 6]

It is clear from Table 6 that Example 7 has a low viscosity and excellent thermal stability. The adhesive strength of the comparative example is excellent, but there is no problem in practically using any adhesive.

[Measurement of Physical Property Retention] A typical high molecular weight block copolymer used as the component (A) in Examples and Comparative Examples, which is an acid dissociated triblock containing an H-Sf-H structure. SX509 to form a thermoplastic copolymer of the type
A, about # 5100 which produces the diblock type block copolymer containing the H-Sf structure, 25 before and after acid dissociation
% Toluene solution viscosity and tensile strength were measured. Dissociation experiment using acidic substance 0.2 parts of stearic acid and 0.5 parts of an antioxidant (Sumilyzer BP101) were added to 100 parts of the polymer, and kneaded at 150 ° C for 45 minutes using a kneader. A 25% toluene solution of the obtained resin and the resin before kneading was prepared. The viscosity of the solution was measured, and the solution was cast to form a film having a thickness of 0.2 to 0.3 mm, and the tensile strength was measured using a tensile tester. The results are shown in Table 7.

[0052]

[Table 7]

In this result, although the tensile strength of the # 5100 after the treatment was 7 kgf / cm ² ,
Actually, it was a clay-like resin, and the strength as an adhesive could not be expected. The above results correspond to the results of Examples 1 to 7, and H-Sf was obtained even after acid dissociation.
This supports the effect of the hot melt adhesive of the present invention in which a high molecular weight block copolymer producing a triblock copolymer having a -H structure is used as a raw material of the component (A), and undergoes the same acid dissociation. If only a polymer having a diblock structure is formed, the effects of the present invention cannot be obtained.

Claims (7)

(57) [Claims] (A) a thermoplastic block copolymer, (B)
A hot melt adhesive composition comprising a tackifier, (C) a stabilizer, and (D) a softener, wherein the component (A) is an acidic substance of a high molecular weight block copolymer used as a raw material. Which contains a structural unit of H-Sf-H type (H indicates a hard segment and Sf indicates a soft segment) in the molecule, and the retention rate of tensile strength is higher than that before the dissociation. 50% or more of the molecular weight block copolymer, and 25% by weight of a 25% by weight toluene solution.
A hot melt adhesive composition having a solution viscosity at 150 ° C. of 150 cps or less. 2. The content of each of the components (A) to (D) in the hot melt adhesive composition is such that the component (A) is 10 to 60% by weight, and the component (B) is 20-80
% By weight, the component (C) is 0.05 to 5% by weight, and the component (D) is 100% by weight of the hot melt adhesive composition. 2. The hot melt adhesive composition according to claim 1, wherein the remaining amount is a subtracted remaining amount. 3. The component (A) includes a thermoplastic block copolymer in which the hard segment H is polystyrene and the soft segment Sf is polyisoprene.
The hot melt adhesive composition according to the above. 4. The content of polystyrene in the thermoplastic block copolymer (A) is 25 to 35% by weight in the thermoplastic block copolymer, and the retention rate of tensile strength is high molecular weight before dissociation. The hot melt adhesive composition according to claim 3, which is 50% or more of the block copolymer, and the 25% by weight toluene solution viscosity (25 ° C) of the thermoplastic block copolymer is 135 cps or less. 5. The thermoplastic block copolymer (A) produced by dissociation with an acidic substance has a polystyrene content of 30 to 35 in the thermoplastic block copolymer.
% By weight, the retention of tensile strength is 50% or more of the high molecular weight block copolymer before dissociation, and the 25% toluene solution viscosity (25 ° C.) of the thermoplastic block copolymer (A) is 100 cps. The hot melt adhesive composition according to claim 3, which is: 6. The composition of claim 1, wherein the component (E) is at least one selected from the group consisting of an ethylene-vinyl acetate copolymer, an ethylene-normal butyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-methyl acrylate copolymer. 2. The hot melt adhesive composition according to claim 1, comprising 5 to 25% by weight of the copolymer. 7. A high molecular weight block copolymer and an acidic substance are mixed and heated to dissociate the high molecular weight block copolymer with the acidic substance, and the H-Sf-H type (H is a hard segment; Sf indicates a soft segment.)
Having a tensile strength retention of 50% or more of the high molecular weight block copolymer before dissociation, and a 25% by weight toluene solution having a solution viscosity at 25 ° C. of 1
A thermoplastic block copolymer of 50 cps or less,
At the time of the dissociation reaction or after the dissociation reaction, a tackifier,
A method for producing a hot melt adhesive composition , further comprising mixing a stabilizing agent and a softening agent .