JPH1046129A - Adhesive composition - Google Patents

Abstract

(57) [Abstract] [Problem] To be excellent in high cohesion force, creep resistance, adhesion / adhesion, and heat stability, and at the same time, the discharge stability of the adhesive in a high-speed coating machine, especially spray coating. Provide an excellent adhesive composition. SOLUTION: (a) It is composed of a vinyl aromatic hydrocarbon and butadiene, and the content of the vinyl aromatic hydrocarbon is 15 to
100 parts by weight of a block copolymer which is 45% by weight,
(B) 400 parts by weight or less, exceeding the tackifying resin 200,
(C) An adhesive composition comprising 0.05 to 5 parts by weight of a phenolic compound represented by the following general formula [1].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an adhesive composition which can be suitably used for assembling disposable articles or members such as disposable diapers, sanitary napkins and bed pad components.

[0002]

2. Description of the Related Art Conventionally, hot melt adhesives used for assembling disposable articles typified by disposable diapers include a rubber-based adhesive mainly composed of a thermoplastic block polymer and an ethylene-based adhesive.
Most of the olefins are mainly composed of synthetic olefins such as propylene-butene copolymers, and rubber-based hot melt adhesives are widely used for bonding particularly where high cohesion and creep resistance are required. Have been. Usually, as a rubber-based hot melt adhesive, a block polymer composed of styrene and isoprene having excellent cold resistance and adhesion / adhesion is often used, but in this case, the cohesive strength is low and the creep resistance is not good. Has problems. When a block polymer composed of styrene and butadiene is used as a rubber-based polymer, cohesive strength and creep resistance are satisfied, but there is a problem that initial tackiness is hardly exhibited.

[0003] In order to exert a high cohesive force on the rubber-based hot melt adhesive as described above, adhesion, tackiness or cold resistance tends to be sacrificed. On the other hand, in recent years, the shape has become more and more complicated due to the diversification of products, and in addition, many new materials have appeared, some of which have poor adhesion,
In some cases, rubber hot melt adhesives cannot cope.

Japanese Patent Application Laid-Open No. 2-1787 discloses a pressure-sensitive adhesive composition using a block polymer comprising a vinyl aromatic hydrocarbon such as styrene and butadiene as a rubber-based polymer. It is disclosed that when a block polymer having a vinyl bond content in a butadiene portion in a specific range is used, the initial tackiness is improved.

The above-mentioned adhesive composition using a block polymer composed of a vinyl aromatic hydrocarbon such as styrene and butadiene as a rubber-based polymer disclosed in Japanese Patent Application Laid-Open No. 2-1787 is improved in initial adhesiveness. However, when applying by a coating method in which the adhesive discharge section of the adhesive coating device does not directly contact the adherend, such as spray coating, the discharge stability during coating is poor and Unevenness,
In the case of a remarkable condition, there are problems such as the stoppage of the discharge and the sudden release of a large amount of the adhesive, which stains the surface other than the bonded portion.

The present inventors have intensively studied the discharge stability of an adhesive in a high-speed coating machine such as an intermittent spray coating machine for a production line for disposable diapers and the like. In an adhesive composition using a block polymer composed of an aromatic hydrocarbon and butadiene, it was found that in order to solve the above-mentioned problem, the blending amount of the tackifier resin had to be set to a remarkably high level. It was completed.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and its object is to
To provide an adhesive composition having high cohesive strength, excellent creep resistance, excellent adhesive / adhesive properties, and excellent thermal stability, and excellent discharge stability of an adhesive in a high-speed coating machine, especially excellent spray coating properties. It is in.

[0008]

According to the present invention, there is provided a block copolymer comprising (a) a vinyl aromatic hydrocarbon and butadiene, wherein the content of the vinyl aromatic hydrocarbon is 15 to 45% by weight. 100 parts by weight of the polymer, (b) more than 400 parts by weight exceeding the tackifier resin 200, and (c) a phenolic compound represented by the following general formula [1] 0.05 to 5:
The gist is an adhesive composition consisting of parts by weight.

Embedded image

The present invention according to claim 2 further comprises:
(D) The adhesive composition according to claim 1, which comprises 10 to 150 parts by weight of a plasticizing oil.

The present invention according to claim 3 provides the adhesive composition according to claim 1 or 2, wherein R ₄ of the phenolic compound represented by the general formula [1] is hydrogen or a methyl group. This is the gist.

[0011] The present invention described in claim 4 provides the invention according to claims 1 to
3. An adhesive composition for disposable articles comprising the adhesive composition according to item 3.

The block copolymer of the component (a) used in the present invention is a copolymer comprising a polymer block of vinyl aromatic hydrocarbon and a polymer block of butadiene,
Other polymer blocks may be contained. As the vinyl aromatic hydrocarbon, for example, styrene, o
-Methylstyrene, p-methylstyrene, p-tert
-Butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene and the like. These may be used alone or in combination of two or more.

When the content of the vinyl aromatic hydrocarbon in the block copolymer of the component (a) is less than 15% by weight, the cohesive strength of the obtained adhesive composition is reduced, and the creep resistance is deteriorated. On the other hand, if the content exceeds 45% by weight, the initial tackiness decreases, so that the content of the vinyl aromatic hydrocarbon in the block copolymer of component (a) is limited to 15 to 45% by weight.

The tackifying resin of the component (b) used in the present invention is preferably one having high compatibility with the block copolymer of the component (a). Almost all common tackifying resins, such as petroleum resins, terpene resins, terpene-petroleum resin copolymers or their fully or partially hydrogenated products, are mentioned. These may be used alone or in combination of two or more.

When the amount of the tackifying resin of the component (b) is 200 parts by weight or less based on 100 parts by weight of the block copolymer of the component (a), not only the adhesion of the obtained adhesive composition is lowered, but also , The spray coatability deteriorates,
If the amount exceeds 400 parts by weight, the obtained adhesive composition becomes hard and brittle, so the amount of the tackifier resin of the component (b) is 200 per 100 parts by weight of the block copolymer of the component (a). It is limited to more than 400 parts by weight and preferably from 210 to 350 parts by weight.

The phenolic compound represented by the general formula [1] of the component (c) used in the present invention includes, for example, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy- 5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl]
-4,6-di-pentylphenyl acrylate and the like. Particularly, those in which R ₄ in the general formula [1] is hydrogen or a methyl group are preferable, and those in which R ₄ is an ethyl group or a propyl group are further preferable. These may be only one kind,
Two or more kinds may be used in combination.

If the amount of the phenolic compound represented by the above general formula [1] of the component (c) is less than 0.05 part by weight based on 100 parts by weight of the block copolymer of the component (a), coloring occurs upon heating. When the amount exceeds 5 parts by weight, the anti-aging performance at the time of heating is saturated, and further effects cannot be expected, and the adhesiveness is adversely affected. The amount of the phenolic compound represented by the general formula [1] is determined by the amount of the block copolymer 1 of the component (a).
The amount is limited to 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight based on 00 parts by weight.

The adhesive composition of the present invention may further comprise, for example, the phenolic compound represented by the general formula [1] of the component (c), if necessary, for example, the general formula [1] of the component (c).
Stabilizers such as phenolic stabilizers other than phenolic compounds represented by, phosphorus-based stabilizers, sulfur-based stabilizers may be used in combination, benzotriazole-based, benzophenone-based,
A benzoate-based ultraviolet absorber may be used in combination.

The preparation of the adhesive composition of the present invention is not particularly limited. For example, the above-mentioned components may be simply heated and mixed using a stirrer, or may be a two-roll roll, a Banbury mixer, a kneader, or an extruder. It may be mixed using a kneading device such as a kneader.

Since the adhesive composition of the present invention is constituted as described above, it is excellent in high cohesive force, creep resistance, adhesion / adhesion, heat stability, and adhesive in a high-speed coating machine. It has excellent discharge stability, especially, excellent spray coating properties.

The adhesive composition according to the second aspect of the present invention comprises a component (d) in addition to the components (a), (b) and (c).
Containing plasticized oil. The plasticizing oil of the component (d) is not particularly limited as long as it is usually used for a hot melt adhesive. However, the viscosity of the adhesive composition can be adjusted and the low-temperature tackiness and flexibility can be improved. It is more preferable if it can improve. Examples of such plasticized oils include oils containing some or all of paraffinic, naphthenic, and aromatic components in a certain ratio.

When the amount of the plasticizing oil of the component (d) is less than 10 parts by weight based on 100 parts by weight of the block copolymer of the component (a), the low-temperature tackiness and flexibility of the obtained adhesive composition are reduced. If the amount is lower than 150 parts by weight, the creep resistance is lowered. Therefore, the amount of the plasticizing oil of component (d) is 10 to 150 parts by weight based on 100 parts by weight of the block copolymer of component (a). Part, preferably 30 to
100 parts by weight. The adhesive composition according to the second aspect of the present invention may optionally contain other plasticizers such as a low-molecular-weight polyolefin-based polymer in addition to the plasticizing oil of the component (d).

Since the adhesive composition according to the second aspect of the present invention is constituted as described above, it is easy to adjust the viscosity of the adhesive composition suitable for use, and to form an adhesive layer having high flexibility. And can further improve low temperature tack.

The adhesive composition according to the third aspect of the present invention is configured as described above, so that the thermal stability can be further improved.

Further, since the adhesive composition according to the fourth aspect of the present invention is constituted as described above, it has high cohesion and creep resistance in a high-speed coating machine such as an intermittent spray coating apparatus. Can be efficiently produced with high ejection stability even when used for assembling disposable articles requiring the following.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples and comparative examples of the present invention are shown below, but the present invention is not limited to these examples.

(Example 1) Styrene-butadiene-styrene (SBS) -based block copolymer (trade name "Taphprene A" manufactured by Asahi Kasei Corporation, styrene content 40% by weight) 10
0 parts by weight, tackifying resin (trade name “Alcon M-100”, manufactured by Arakawa Chemical Co., Ltd., hydrogenated alicyclic saturated hydrocarbon resin) 25
0 parts by weight, 60 parts by weight of plasticizing oil (trade name "Shellflex 371N" manufactured by Shell Chemical Company, USA) and a heat stabilizer (trade name "Sumilyzer G" manufactured by Sumitomo Chemical Co., Ltd.)
M ", 1 part by weight of 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate was heated and mixed at 160 ° C. to prepare an adhesive composition. did.

(Example 2) Styrene-butadiene-styrene (SBS) -based block copolymer (trade name "TUFPREN 315", manufactured by Asahi Kasei Corporation, styrene content: 20% by weight)
100 parts by weight, 350 parts by weight of a tackifier resin (trade name "Alcon M-100", manufactured by Arakawa Chemical Co., Ltd., hydrogenated alicyclic saturated hydrocarbon resin), plasticized oil (trade name, manufactured by Shell Chemical Company, USA) "Shelflex 371N") 60
1 part by weight of a heat stabilizer (manufactured by Sumitomo Chemical Co., Ltd., trade name "Sumilyzer GM") was heated and mixed at 160 ° C. to prepare an adhesive composition.

Example 3 1 part by weight of the heat stabilizer of Example 1 (manufactured by Sumitomo Chemical Co., Ltd., trade name "Sumilyzer GM", a phenolic compound represented by the general formula [1]) was added to (Sumitomo Chemical Co., Ltd.) , Trade name "Sumilyzer GS", 2- [1- (2-
(Hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate An adhesive composition was prepared in the same manner as in Example 1, except that 1 part by weight was used. .

(Comparative Example 1) Except that the addition amount of the tackifying resin in Example 1 was changed from 250 parts by weight to 150 parts by weight,
An adhesive composition was prepared in the same manner as in Example 1.

Comparative Example 2 An adhesive composition was prepared in the same manner as in Example 1 except that the heat stabilizer of Example 1 was not used.

Comparative Example 3 Except that the addition amount of the tackifying resin of Example 1 was changed from 250 parts by weight to 500 parts by weight, and the addition amount of the plasticizing oil was changed from 30 parts by weight to 30 parts by weight. An adhesive composition was prepared in the same manner as in Example 1.

In order to evaluate the adhesive compositions obtained in Examples and Comparative Examples, creep resistance, spray coating properties, and heat stability (heat stability 1 and heat stability 2) were evaluated as follows. Tested. The test results are shown in Table 1.

1. Creep resistance: The obtained adhesive composition was applied to a polyethylene terephthalate (PET) film having a thickness of 25 μm at a thickness of about 50 μm, cut into a width of 25 mm, and then subjected to T-peel creep at a measurement condition of 50 ° C. ,
The peel length after 3 hours under a load of 100 g was measured.

2. Spray coatability: The obtained adhesive composition is intermittently discharged by a spray gun used in a disposable diaper assembling line in the same manner as in a production line, to prevent coating unevenness on the adherend surface and scattering of the adhesive composition. The state was visually observed. ○: Applicable without coating non-uniformity, without scattering to the area other than the bonding site, ×: Evaluation of coating quality with uneven coating and contamination other than the bonding area. did.

3. Heat stability: [Thermal stability 1]: 50 g of the obtained adhesive composition was placed in a glass bottle and heated in a hot air circulating drier at 180 ° C. for 72 hours without a lid, and the adhesive composition in a molten state was obtained. Observation of the occurrence of carbides and other foreign matter in the object visually,
○: Carbide or other foreign matter is not observed,
×: Evaluation was made in two stages: carbide and other foreign matters were generated.

[Thermal stability 2]: 100 g of the obtained adhesive composition was placed in a glass bottle, heated in a hot air circulating drier at 150 ° C. for 72 hours without covering, and the melt viscosity at the same temperature was measured. And the melt viscosity immediately after heating to 150 ° C., and the rate of change was evaluated in units of 5%.

[0038]

[Table 1]

[0039]

Since the adhesive composition of the present invention is constituted as described above, it is excellent not only in high cohesive force, creep resistance, adhesion / tackiness and heat stability but also in good spray coating. It has workability. Therefore, in recent years, the diapers, sanitary napkins, and the like, in which the materials used and their configurations have become increasingly diversified, complicated, and accelerated to make the bonding process difficult.
It can be suitably used for assembling disposable products or members such as bed pad constituent members.

Claims (4)

[Claims] (1) (a) It comprises a vinyl aromatic hydrocarbon and butadiene, and the content of the vinyl aromatic hydrocarbon is 15 to
100 parts by weight of a block copolymer which is 45% by weight, (b) 400 parts by weight or less exceeding the tackifier resin 200, and (c) 0.05 to 5 parts by weight of a phenolic compound represented by the following general formula [1]. An adhesive composition comprising: Embedded image 2. The adhesive composition according to claim 1, further comprising (d) 10 to 150 parts by weight of a plasticizing oil. 3. The adhesive composition according to claim 1, wherein R ₄ of the phenolic compound represented by the general formula [1] is hydrogen or a methyl group. 4. An adhesive composition for disposable articles, comprising the adhesive composition according to claim 1.