JP3157256B2 - Adhesive resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-melt type adhesive having excellent initial tackiness (tack), adhesive strength (peel strength), creep characteristics (holding power), low melt viscosity and excellent melt stability. The present invention relates to an adhesive resin composition. The composition of the present invention provides a composition suitable for use in pressure-sensitive adhesive tapes and labels, including the field of sanitary materials such as disposable diapers and sanitary napkins.

[0002]

2. Description of the Related Art Conventionally, pressure-sensitive adhesives have been used for various applications such as pressure-sensitive adhesive tapes and labels. Conventionally, a method of applying an adhesive to these tapes by applying an adhesive solvent obtained by dissolving the adhesive in a solvent to a base material by means such as a roll or a spray has been adopted. However, the use of such a solvent involves many problems in terms of air pollution, fire, working environment, hygiene and the like, and therefore hot-melt adhesives that do not use a solvent are becoming common.

The properties required of such a hot-melt type pressure-sensitive adhesive are good adhesive properties. (Tack, peel strength, holding power) There should be no change in viscosity, coloring, or reduction in adhesive properties due to heating and melting. Good fluidity during melting and excellent coating stability. And the like.

[0004] In particular, recently, the coating apparatus has been improved, and the type in which the adhesive is applied in a thread form from a thin nozzle has been replaced by an adhesive. The adhesive has a lower melt viscosity, and has little change in quality with respect to long-term melt retention. There is a demand for a hot-melt pressure-sensitive adhesive having excellent properties. However, there is no actual hot-melt pressure-sensitive adhesive of the related art that satisfies all of the above requirements.

[0005] For example, Japanese Patent Publication No. 44-17037,
Japanese Patent Publication No. 47-21720 discloses a hot-melt pressure-sensitive adhesive using a block copolymer of styrene-butadiene-styrene or styrene-isoprene-butadiene-styrene. However, although they have excellent adhesive strength, they are severely deteriorated by heating and cannot be used stably.

In order to improve the thermal stability, a pressure-sensitive adhesive using a styrene-ethylene / butylene-styrene block copolymer obtained by hydrogenating a conjugated diene moiety is disclosed in US Pat. No. 3,427,269 and Japanese Patent Publication No. 55-7875. It is disclosed in the gazette. However, although the thermal stability is improved by hydrogenation, the adhesive strength is significantly reduced. Further, since the melt viscosity is high, not only the use conditions are restricted, but also the type of the tackifier used is restricted.

Japanese Patent Application Laid-Open No. 2-1788 discloses the use of a hydrogenated block copolymer having a combination of a triblock structure and a specific block structure. However,
In this combination, the balance between melt viscosity, tack and holding power is insufficient, and in particular, tack is insufficient. JP-A 1-2
No. 0284 discloses an adhesive using a block copolymer having a specific hydrogenation rate. This pressure-sensitive adhesive composition has insufficient tack and melt viscosity.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an excellent adhesive property such as holding power while having a low melt viscosity, and a small change in the melt viscosity and the adhesive property with respect to the melt retention. An object of the present invention is to provide a hot melt type pressure-sensitive adhesive.

[0009]

Means for Solving the Problems The inventors of the present invention have used a pressure-sensitive adhesive composition using a hydrogenated block copolymer to obtain excellent heat stability and to use a non-hydrogenated block copolymer. Combining the excellent adhesive properties of the adhesive composition,
In addition, as a result of intensive studies on the pressure-sensitive adhesive composition having a low melt viscosity, the total hydrogenation rate of the conjugated diene portion was suppressed to 35% or less, and the vinyl bond in the conjugated diene portion was selectively hydrogenated to reduce the amount of vinyl bond. Was reduced to 3% or less, and it was found that the object was achieved by using a specific block copolymer having a specific structure, thereby completing the present invention.

That is, the present invention relates to (a) a polymer block A mainly composed of at least two vinyl aromatic compounds and a polymer block B mainly composed of at least one conjugated diene.
A partially hydrogenated block copolymer, wherein 35% or less of a conjugated diene moiety in the polymer is hydrogenated;
(B) It has one polymer block C mainly composed of a vinyl aromatic compound and at least one polymer block D mainly composed of a conjugated diene, and 35% or less of the conjugated diene portion in the polymer is not more than 35%. A hydrogenated partially hydrogenated block copolymer, and (a) and (b) each having a vinyl bond of 8 to 20% in a conjugated diene portion before hydrogenation,
(A) and (b) each have a vinyl bond in the conjugated diene portion after hydrogenation of 3% or less, and the content of each of the vinyl aromatic compounds of (a) and (b) is 20 to 45% by weight; a)
And (b) are in a ratio of 80/20 to 20/80 (% by weight), and MI (G) of the combination of (a) and (b) is 1
The adhesive resin composition comprises 100 parts by weight of a partially hydrogenated block copolymer of 50 to 10 g / 10 min and (c) 40 to 400 parts by weight of a tackifier.

A first feature of the present invention is that the vinyl bond in the conjugated diene portion in the block copolymer to be used is selectively hydrogenated to reduce the vinyl bond amount to 3% or less. Thus, the thermal stability of the hot melt pressure-sensitive adhesive was remarkably improved. The second feature is that the total hydrogenation rate of the block copolymer is kept low at 35% or less, whereby the excellent tack characteristic of the non-hydrogenated block copolymer is maintained. At the same time, the low-temperature performance is better than that of the completely hydrogenated block copolymer, and the range of selection of the tackifier is wider.

A third feature is that by blending the component (b) having one block C mainly composed of a vinyl aromatic compound, the melt viscosity of the hot-melt pressure-sensitive adhesive composition can be significantly reduced. That is, it is possible to mix the component (a) having a higher molecular weight than the conventional one, so that a high holding power is obtained, a low melt viscosity, and an excellent balance of tackiness. That is, an adhesive composition was obtained.

Hereinafter, the present invention will be described in detail. The component (a) and the component (b), which are the partially hydrogenated block copolymers used in the pressure-sensitive adhesive composition of the present invention, have a vinyl aromatic compound content and a microstructure (a vinyl bond amount before hydrogenation, a vinyl bond amount after hydrogenation). The vinyl bond amount), the total hydrogenation ratio, and the molecular weight may be the same or different as long as they are within the ranges described in the claims.

The polymer blocks A and C mainly composed of a vinyl aromatic compound are composed of a vinyl aromatic compound homopolymer, or a copolymer of a vinyl aromatic compound and a conjugated diene and a vinyl aromatic compound homopolymer. And a block copolymer having a vinyl aromatic compound content of at least more than 50% by weight, preferably 70% by weight or more. The molecular weights of the vinyl aromatic compound homopolymers in the plurality of polymer blocks A contained in the component (a) may be the same or different. The molecular weight of the vinyl aromatic compound homopolymer in the polymer block C contained in the component (b) may be equal to or different from the molecular weight of the vinyl aromatic compound homopolymer in the polymer block A, In order to obtain high holding power, it is preferable that the vinyl aromatic compound homopolymers of the polymer blocks A and C have substantially the same molecular weight.

The molecular weight of these vinyl aromatic compound homopolymers can be measured using GPC after decomposing the block copolymer with osmic acid. The polymer blocks B and D mainly composed of a conjugated diene are composed of a conjugated diene homopolymer and / or a copolymer of a vinyl aromatic compound and a conjugated diene, and have a conjugated diene content of at least 50% by weight. Over, preferably 70% by weight
This is the above block copolymer.

The distribution of the vinyl aromatic compound in the copolymer portion of the vinyl aromatic compound and the conjugated diene in the partially hydrogenated block copolymer of component (a) and component (b) is uniform and random. It may be a shape distribution, a so-called tapered shape in which the monomer composition increases and decreases along the molecular chain, or a combination thereof. These partially hydrogenated block copolymers may be produced by any known method as long as they satisfy the claims, but are generally prepared first in a non-polar solvent such as hexane or cyclohexane. In an organic alkali metal, typically using butyllithium as an initiator, a block copolymer obtained by anionic polymerization with a small amount of polar compound tetrahydrofuran or tetramethylethylenediamine added as necessary, titanium It can be obtained by reacting with hydrogen in the presence of a catalyst such as a compound, and can be represented by the following general formula.

That is, the partially hydrogenated block copolymer constituting the component (a) is

[0018]

Embedded image

The partially hydrogenated block copolymer constituting the component (b) is CD or DCD. (In the above formula, A, B, C and D are symbols used in the description of the claims, A and C are polymer blocks mainly composed of vinyl aromatic compounds, and B and D are conjugated dienes. And n is an integer of 1 or more, and X is a polyfunctional initiator residue or tin tetrachloride,
Known coupling agent residues such as silicon chloride and polyepoxy compounds. Examples of the method for polymerizing these block copolymers include those described in JP-B-36-19286, JP-B-43-14979, and JP-B-49-36957.

In addition, these components (a) and (b)
May be a mixture of block copolymers represented by the above general formula. Examples of the vinyl aromatic compound used in the present invention include styrene, α-methylstyrene, p-methylstyrene, alkylstyrene such as p-tert-butylstyrene, vinylnaphthalene, vinylanthracene, and the like. May be. A representative compound is styrene.

The conjugated diene used in the present invention includes 1, 1
3-butadiene, isoprene, 2,3-dimethyl-1,
3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 3,4-dimethyl-1,3-hexadiene,
There are 4,5-diethyl-1,3-octadiene, phenylbutadiene and the like, and two or more of these may be used.
A representative compound is butadiene.

The content of the vinyl aromatic compound in the partially hydrogenated block copolymer of the components (a) and (b) used in the present invention is from 20 to 45% by weight, preferably from 25 to 45% by weight.
40% by weight. When the content of the vinyl aromatic compound exceeds 45% by weight, the tack decreases, and when the content is less than 20% by weight, the holding power becomes poor. The microstructure of the conjugated diene portion in the partially hydrogenated block copolymer used in the present invention has a vinyl bond amount before hydrogenation of 8 to 20%, preferably 8 to 18%, and a vinyl bond amount after hydrogenation. It is at most 3%, preferably at most 2.5%, more preferably at most 2%. Here, the vinyl bond amount means, among conjugated dienes incorporated in the block copolymer,
This is the ratio of those incorporated in the form of 1,2-bonds or 3,4-bonds and having unsaturated double bonds in the side chains, excluding those in which the double bonds have been saturated by hydrogenation. An adhesive composition using a partially hydrogenated block copolymer having a vinyl bond content of more than 3% after hydrogenation is inferior in melt stability, and the melt viscosity increases when melted for a long time.

When hydrogenation is carried out in order to keep the vinyl bond content after hydrogenation at 3% or less, the total hydrogenation rate is 35%.
Or less, preferably 30% or less. Hydrogenation rate is 35
%, The amount of hydrogenation of the double bond in the main chain other than the vinyl bond increases, a long-chain methylene group is formed, and the polymer block mainly composed of a conjugated diene becomes crystalline, resulting in a good adhesive composition. I can't get anything.

In order to keep the total hydrogenation rate at 35% or less and to keep the vinyl bond content after hydrogenation at 3% or less, it is preferable that the vinyl bond content before hydrogenation be as small as possible. Therefore, when a small amount of a polar compound is used to narrow the molecular weight distribution of the block copolymer and improve tack, the vinyl bond increases, so that the vinyl bond amount before hydrogenation becomes 20% or less. These polar compounds are used in the range. In addition, the minimum vinyl bond content at which a block copolymer can be stably produced using an organic alkyl metal initiator is about 8%.

The microstructure of these conjugated diene moieties is measured using a nuclear magnetic resonance apparatus (NMR). That is,
Using a high-resolution NMR of 200 MHz or more, the amount of non-hydrogenated vinyl bonds and the amount of double bonds in the main chain,
The hydrogenated vinyl bond amount and the backbone double bond amount can be determined. The term “total hydrogenation ratio” as used herein refers to the case where all conjugated diene moieties in the block copolymer are hydrogenated to form a saturated bond, with 100% being the hydrogen content of the conjugated diene moieties in the block copolymer. It refers to the ratio of added conjugated diene moieties.

The amount of vinyl bonds before hydrogenation can be controlled by changing the polymerization temperature or by blending a polar compound.
It can be controlled by appropriately selecting the type of hydrogenation catalyst used, the reaction temperature, and the total hydrogenation rate.
Specific methods for hydrogenating the block copolymer are described in JP-A-59-133203 and JP-A-60-2.
The method described in JP-A-20247 can be used.

As a method for hydrogenating the block copolymer, known methods other than those described above may be used, but the total hydrogenation rate, the amount of vinyl bonds after hydrogenation, etc. are within the scope of the present invention. It is necessary to set appropriate conditions. Also,
The hydrogenation rate of the aromatic double bond of the vinyl aromatic compound is not particularly limited.

Component (a) and component (b) used in the present invention
The mixing ratio of each partially hydrogenated block copolymer is 80/20
20/80, preferably 70/30 to 30/70 (% by weight). If the amount of component (a) is less than 20% by weight, the holding power is insufficient, and if it exceeds 80% by weight, the melt viscosity is so high that it cannot be used as a hot melt adhesive. Regarding the molecular weight of each of the component (a) and the component (b), it is preferable that the molecular weight of the component (a) is larger than that of the component (b) from the viewpoint of holding power and tack. In order to reduce the melt viscosity as a hot melt type pressure-sensitive adhesive, the melt flow (MI, 200
℃, load 5Kg: G condition) 1-50g / 10min,
Preferably 5 to 40 g / 10 min, more preferably 5
３０30 g / 10 min. MI is 40g / 10mi
If n is exceeded, sufficient holding power cannot be obtained, and 1 g / 10
If it is less than min, the melt viscosity will be high and it cannot be used as a hot melt type pressure sensitive adhesive. The number average molecular weight that satisfies these conditions is 40,000 to 100,000 for component (a) and 10,000 to 80,000 for component (b). These molecular weights can be measured by a conventional method using gel permeation chromatography (GPC).

These partially hydrogenated block copolymers, component (a) and component (b) may be separately polymerized and hydrogenated to have different microstructures, or they may be used in parallel in the same reactor. Polymerized and hydrogenated at the same time. Alternatively, the component (a) may be produced by a coupling reaction using a part of the block polymer of the component (b) before the hydrogenation and hydrogenated, and a material having a uniform microstructure may be used.

The partially hydrogenated block copolymer used in the present invention may be modified by an addition reaction with an unsaturated carboxylic acid or a derivative thereof to contain a functional group. Specific examples of the modifying agent include maleic anhydride, glycidyl methacrylate and the like. Further, as the partially hydrogenated block copolymer used in the present invention, a block copolymer in which a polar group-containing atomic group is bonded to at least one polymer terminal of the block copolymer can also be used. More specifically, among the terminal-modified block copolymers described in JP-A-62-86074, terminal-modified block copolymers that fall within the scope of the present invention can also be used.

The tackifier of the component (c) used in the present invention is one which has been conventionally used as a tackifier in a hot-melt type pressure-sensitive adhesive, for example, chroman-indene resin, phenol resin, p-tercia. Rubutylphenol / acetylene resin, phenol / formaldehyde resin, terpene / phenol resin, polyterpene resin, xylene / formaldehyde resin, synthetic polyterpene resin, aromatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, oligomer of monoolefin and diolefin , Hydrogenated hydrocarbon resin, hydrocarbon-based tackifying resin, polybutene, polyhydric alcohol ester of rosin, hydrogenated terpene resin, hydrogenated rosin, hydrogenated wood rosin, ester of monohydric or polyhydric alcohol with hydrogenated rosin, Turpentine adhesive And the like is given agents, and the like. More specifically, those described in "Rubber Plastic Compounding Chemicals" (edited by Rubber Digest Co., Ltd.) can be used.

In the present invention, the tackifier of the component (c) is used in an amount of 40 to 400 parts by weight, preferably 100 parts by weight, per 100 parts by weight of the partially hydrogenated block copolymer comprising the components (a) and (b). Used in the range of ~ 300 parts by weight. The pressure-sensitive adhesive composition of the present invention may optionally contain a softener, a reinforcing resin, an antioxidant, an ultraviolet absorber, a coloring agent, and the like.

The softener is a petroleum softener (paraffin oil, naphthene oil, aroma oil, etc.), paraffin, vegetable oil softener, plasticizer and the like. (Edited by Rubber Digest) can be used. The softener is used in an amount of 5 to 200 parts by weight, preferably 20 to 100 parts by weight, based on 100 parts by weight of the partially hydrogenated block copolymer comprising the components (a) and (b).

The pressure-sensitive adhesive composition of the present invention can be produced by a method in which each of the above-mentioned raw materials is put into a melting and mixing vessel equipped with a stirrer and mixed by heating. INDUSTRIAL APPLICABILITY The pressure-sensitive adhesive composition of the present invention is useful as a pressure-sensitive adhesive for various sheets and tapes, and can be used particularly in the field of sanitary materials such as disposable diapers and sanitary napkins.

[0035]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which by no means limit the present invention. (I) Preparation of Partially Hydrogenated Block Copolymers A, B, and C A cyclohexane solution containing 8.8 parts by weight of styrene was charged into a stainless steel polymerization kettle equipped with a stirrer under a nitrogen atmosphere.
A hexane solution containing 0.037 parts by weight of n-butyllithium was added and polymerized at 60 ° C. for 1 hour. Next, a cyclohexane solution containing 16.3 parts by weight of butadiene was added and polymerized for 1.5 hours. Next, a hexane solution containing 0.074 parts by weight of n-butyllithium and a cyclohexane solution containing 48.7 parts by weight of butadiene were sequentially added, and polymerized for 1.5 hours. Next, a cyclohexane solution containing 26.2 parts by weight of styrene was added to carry out polymerization for 1 hour.

Subsequently, a hydrogenation reaction was carried out at 60 ° C. using 5 kg / cm ² of hydrogen gas with a titanium-based catalyst according to the methods described in Examples 1 to 9 of JP-A-59-133203. Was. The supply rate of hydrogen gas was controlled so that the hydrogenation rate became 25%. To the obtained partially hydrogenated block copolymer solution was added 0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol and 0.5 parts by weight of tris (nonylphenyl) phosphite, and the solvent was added. Was removed by heating to obtain a partially hydrogenated block copolymer A. The total hydrogenation rate and the amount of vinyl bonds were determined by NMR (200
MHz) with deuterated chloroform.

The partially hydrogenated block copolymer B was prepared by using a hydrogenation catalyst using cobalt naphthenate and triethylaluminum at a hydrogen gas pressure of 70 kg / cm ² , except that the hydrogenation reaction was carried out. Addition block copolymer A
It was obtained by polymerization and hydrogenation in the same manner as described above. Similarly to the partially hydrogenated block copolymer B, the partially hydrogenated block copolymer C is a palladium-carbon supported catalyst, and the hydrogen gas pressure is set to 50 kg / h.
The polymer was obtained by polymerization and hydrogenation in the same manner as in the partially hydrogenated block copolymer A, except that the hydrogenation reaction was carried out at a pressure of ² cm ² . The catalyst was removed by filtration.

(II) Partially hydrogenated block copolymer D,
Adjustment of E, F, G, H The partially hydrogenated block copolymers D, E, F, G, and H were prepared in the same manner as the partially hydrogenated block copolymer A by changing the amount of the polymerization catalyst and the amount of hydrogen gas used. H was obtained. (III) Preparation of partially hydrogenated block copolymers I to W n-butyllithium was added to a cyclohexane solution containing 35 parts by weight of styrene in the reactor used for partially hydrogenated block copolymer A to complete polymerization. And then butadiene 6
A cyclohexane solution containing 5 parts by weight was added to complete the polymerization, and further a block copolymer partially synthesized using a bifunctional bisphenol A-type epoxy compound was synthesized. The same block copolymer A as the partially hydrogenated block copolymer A was synthesized. Hydrogenation was carried out by the method to obtain partially hydrogenated block copolymers I to W. The weight ratio of component (a) to component (b) and MI were adjusted by changing the amounts of the epoxy compound and the polymerization catalyst. The partially hydrogenated block copolymers N and O were polymerized by charging the amounts of styrene and butadiene shown in Table 3. During the polymerization of the partially hydrogenated block copolymers P, Q, and R, tetramethyleneethylenediamine was added to adjust the amount of vinyl bonds.

(IV) Preparation of Partially Hydrogenated Block Copolymer X Using the reaction vessel used for the partially hydrogenated block copolymer A, 6
At 0 ° C., 0.004 parts by weight of tetramethylenediamine and a hexane solution containing 0.021 parts by weight of n-butyllithium were added to a cyclohexane solution containing 7 parts by weight of styrene to complete the polymerization, and then 13 parts by weight of butadiene was added. The polymerization was completed by adding a cyclohexane solution containing a part thereof. Next, a hexane solution containing 0.063 parts by weight of n-butyllithium, 0.011 parts by weight of tetramethylenediamine, and a cyclohexane solution containing 48 parts by weight of butadiene were sequentially added to complete the polymerization, and 28 parts by weight of styrene was further added. A cyclohexane solution containing 4 parts by weight of butadiene was added sequentially to complete the polymerization of each monomer. Next, hydrogenation was performed in the same manner as in the partially hydrogenated block copolymer A to obtain a partially hydrogenated block copolymer X.

(V) Preparation of Pressure-Sensitive Adhesive Composition and Evaluation of Each Property A partially hydrogenated block copolymer, a tackifier, a softener, and an antioxidant are blended in a predetermined mixture, and are melt-mixed using a kneader and hot-mixed. A melt-type adhesive was prepared. The adhesive property was measured by applying a hot-melt adhesive to a polyethylene terephthalate sheet and using stainless steel (SUS304) as an adherend.

Melt Viscosity The pressure-sensitive adhesive composition was measured for melt viscosity at 180 ° C. using a Brookfield viscometer. (Rotation speed:
100 rpm: rotor: No. 21) Loop tack It was measured under the following conditions using a loop-shaped sample having a width of 250 mm × 15 mm.

(Adhesion area: 15 mm × 50 mm, adhesion time: 3 sec, adhesion and peeling speed: 500 mm / m
in) Peel strength A sample having a width of 25 mm was attached to a stainless steel plate, and a 180-degree peel force was measured. (Peeling speed: 300 mm / mi
n) Holding force A 1 kg load was applied to the bonded portion having an adhesive area of 25 mm × 25 mm, and the time required for falling under an atmosphere at a temperature of 60 ° C. was measured.

Thermal stability The pressure-sensitive adhesive composition was left for 96 hours in an atmosphere at a temperature of 180 ° C., and the melt viscosity was measured.

[0044]

Examples 1 to 3 and Comparative Examples 1 to 5 Using partially hydrogenated block copolymers A to H shown in Table 1, based on 100 parts by weight of each block copolymer, Alcon M100 was used as a tackifier. 270 parts by weight (manufactured by Arakawa Chemical Co., Ltd.), 65 parts by weight of PW-90 (manufactured by Idemitsu Kosan Co., Ltd.) as a softener, and 1 part by weight of Sumilizer GM (manufactured by Sumitomo Chemical Co., Ltd.) as an antioxidant were melt-mixed at 180 ° C. Thus, a hot melt type pressure-sensitive adhesive composition was prepared. Table 2 shows the measurement results of the adhesive properties.

FIG. 1 shows 180 of the pressure-sensitive adhesive composition of Example 1.
The molecular weight distribution was measured using GPC before (solid line) and after (dotted line) the melting retention at 4 ° C. for 4 days. The molecular weight distribution hardly changed. FIG. 2 shows the molecular weight distributions of the pressure-sensitive adhesive composition of Comparative Example 4 before and after the melt retention (solid line) and after (dotted line) measured by GPC. It was found that the cross-linking reaction proceeded due to the retention of the melt, and the molecular weight distribution was broadened.

A hot-melt type pressure-sensitive adhesive using a partially hydrogenated block copolymer having a vinyl bond content of more than 4% after hydrogenation was inferior in heat stability, and the melt viscosity increased greatly due to the retention of the melt. When the total hydrogenation ratio was more than 35%, a hot-melt pressure-sensitive adhesive was obtained which exhibited crystallinity due to long-chain methylene bonds and had poor tack.

[0047]

Examples 4 to 14 and Comparative Examples 6 to 10 Using the partially hydrogenated block copolymers I to X shown in Table 3, hot-melt pressure-sensitive adhesive compositions were prepared in the same composition as in Example 1. . Table 4 shows the measurement results of those adhesive properties. When the amount of the component (a) exceeds 80% by weight, the tack was inferior, and when the amount of the component (b) exceeded 80% by weight, the holding power was inferior.

Those having a vinyl bond content of more than 20% before hydrogenation had poor stability because the vinyl content after hydrogenation exceeded 3%. If the MI is less than 1 g / 10 min, the melt viscosity is large, the tack is poor, and the
Those having more than / 10 min had poor holding power.

[0049]

Examples 15 to 17 Using partially hydrogenated block copolymers A, I and X in Tables 1 and 3, 100 parts by weight of each partially hydrogenated block copolymer was used as a tackifier. 250 parts by weight of Alcon M100 (manufactured by Arakawa Chemical)
50 parts by weight of PW-90 (manufactured by Idemitsu Kosan Co., Ltd.) as a softener and 1 part by weight of Sumilizer GM (manufactured by Sumitomo Chemical Co., Ltd.) as an antioxidant are melt-mixed at 180 ° C. to prepare a hot-melt adhesive composition. did. Table 5 shows the measurement results of the adhesive properties.

It was found that all of them had good heat stability and adhesive properties.

[0051]

According to the present invention, there is provided a hot melt pressure-sensitive adhesive composition using a partially hydrogenated block copolymer having a specific structure,
This is a pressure-sensitive adhesive composition that is well-balanced in low melt viscosity, pressure-sensitive properties and stability, suitable for hot-melt pressure-sensitive adhesives.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

[Table 4]

[0056]

[Table 5]

[Brief description of the drawings]

FIG. 1 is a graph showing the molecular weight distributions of a pressure-sensitive adhesive composition of Example 1 before and after retention in a melt measured by GPC.

FIG. 2 is a graph showing the molecular weight distributions of the pressure-sensitive adhesive composition of Comparative Example 4 before and after the melt retention, measured by GPC.

Claims (1)

(57) [Claims] 1. A polymer having at least two polymer blocks A mainly composed of a vinyl aromatic compound and at least one polymer block B mainly composed of a conjugated diene, wherein the conjugated diene in the polymer is contained. (B) a polymer block C composed mainly of one vinyl aromatic compound and a polymer composed mainly of at least one conjugated diene; A partially hydrogenated block copolymer having a coalesced block D, wherein 35% or less of the conjugated diene portion in the polymer is hydrogenated, and each of (a) and (b) before hydrogenation 8-20% of vinyl bonds in the conjugated diene portion, (a)
And (b) each have a vinyl bond of 3% or less in the conjugated diene portion after hydrogenation, each of (a) and (b) has a vinyl aromatic compound content of 20 to 45% by weight, and (a) The compounding ratio with (b) is 80/20 to 20/80 (% by weight), and the MI (G) of the combination of (a) and (b) is 1
(C) an adhesive resin composition comprising 40 to 400 parts by weight of an adhesion-imparting agent;