JP2019119870A - Hot-melt composition - Google Patents

Abstract

To provide: a hot-melt composition which has a melt viscosity low enough to allow automatic application by a general-purpose hot-melt applicator, has excellent sealability in spite of high moldability and releasability, and also inhibits bleed-out of a liquid softener; and a sealant using the same.SOLUTION: The hot-melt composition contains a styrenic block copolymer (A) and a liquid softener (B), and is characterized in that: (1) the styrenic block copolymer (A) is a hydrogenation product of at least one styrenic copolymer selected from the group consisting of styrene-isoprene-styrene (SIS) copolymers, styrene-butadiene-styrene (SBS) copolymers and styrene-isoprene-butadiene-styrene (SIBS) copolymers; (2) the content of the liquid softener (B) is 150-450 pts.mass based on 100 pts.mass of the styrenic block copolymer (A); and (3) in the hot-melt composition, the viscosity ratio (η1/η2) of the melt viscosity at 140°C (η1) to the melt viscosity at 180°C (η2) is from 2 to 15, and the melt viscosity at 180°C is 2000 mPa s or less.SELECTED DRAWING: None

Description

  The present invention relates to a hot melt composition, and more particularly to a hot melt composition excellent as an industrial sealing material used for joints of various assembly members.

  In industrial fields such as home appliances, automobiles, and buildings, various industrial sealing materials are used to seal various members (or parts) for the purpose of dust prevention, waterproofing, and the like.

As such industrial sealing materials, for example, the following can be exemplified:
Reaction-solidifying sealing materials such as silicone-based sealing materials, urethane-based sealing materials, butyl rubber-based sealing materials, polysulfide-based sealing materials, molded packings made of natural rubber, synthetic rubber, etc .; and styrene-based hot melt-type sealing materials, butyl-based hot materials Thermoplastic hot melt type sealing materials such as melt type sealing materials.

  In recent years, automation of member assembly processes has been promoted in order to increase the efficiency of production sites in each industrial field, and the efficiency improvement by the automatic application of a sealing material using an applicator or the like is required. As an aspect of such automatic application, an aspect in which a sealing material is directly applied to a part to be sealed using an applicator or the like, an aspect in which a sealing material is directly injected into a mold in order to obtain a sealing material as a molding. Etc.

  However, the above sealing material has the following problems.

  For example, although a reaction hardening seal material can be applied automatically by an applicator etc., reaction hardening of the seal material proceeds in the applicator at the time of line stoppage or interruption due to leave or line trouble, so when the line restarts It requires internal cleaning and is not suitable for complete automation. Further, since the reaction is solidified, the progress of the reaction is not constant due to the temperature or humidity of the coating environment, and therefore, the degree of proficiency is required for actual use.

  In addition, when a reaction-hardening-type sealing material is poured into a mold or the like and the shape is formed into a shape that conforms to the assembly member, it takes time to obtain a molded product by reaction solidification, which is considered unsuitable for automation. Also, there is room for improvement in releasability.

  On the other hand, a thermoplastic hot melt type sealing material is reported as a sealing material having high peelability and small compression set (see Patent Documents 1 and 2).

  Patent Document 1 has a hydroxyl value of 20 to 200 (mg KOH / g) per 100 parts by weight of SEEPS (styrene-ethylene-ethylene-propylene-styrene copolymer) having a weight average molecular weight of 250,000 or more. A hot melt composition is disclosed which contains 5 to 500 parts by mass of a terpene phenol resin and 350 to 2000 parts by mass of a hydrocarbon plasticizer. Moreover, it is described that the predetermined hot-melt composition is excellent in the sealing property with respect to a polyolefin base material, and disassemblability.

In Patent Document 2, (B) heat resistant polymer (B) heat resistant polymer: 1 to 200 parts by weight per 100 parts by weight of (A) styrenic thermoplastic elastomer, (C) liquid selected from process oil, liquid rubber and their modified products A resin composition comprising 5 to 100 parts by weight of a softener and 5 to 250 parts by weight of a (D) tackifier, wherein the resin composition further comprises air bubbles is disclosed. Further, although the predetermined resin composition has high peelability, it has excellent sealing properties and heat resistance, substantially no bleed-out, and improved compression set and the like, and can be used as sealing materials, adhesives and the like. It is stated that it is suitable.

Patent No. 4918845 gazette JP, 2005-60499, A

  However, when using the hot melt composition and resin composition of patent document 1, 2 as a thermoplastic hot melt type sealing material, it is pointed out that there exist the following problems.

  For example, in the hot melt composition of Patent Document 1, there is a problem that the liquid softener may be bled out by containing a large amount of liquid softener (such as oil) to secure fluidity.

  In addition, when the content of the liquid softener is reduced, the melt viscosity of the hot melt composition becomes high, and there is a problem that the coating suitability is poor. For this reason, when using a hot melt applicator, it is necessary to make the coating temperature higher than the normal temperature, and the properties of the hot melt composition change due to thermal deterioration, generating an unpleasant odor, and the safety of the user. There is a problem that the sex declines. Furthermore, even when it is poured into a mold and formed into a shape that conforms to the assembly member, there is a problem that molding defects are likely to occur because the melt viscosity is too high.

  In the resin composition of Patent Document 2, although the content of the liquid softener is smaller than that of the hot melt composition of Patent Document 1, bleed-out hardly occurs, but the melt viscosity of the resin composition becomes high and the coating is applied There is a problem that it is inferior to work aptitude. For this reason, as in the case of Patent Document 1, when using a hot melt applicator, it is necessary to make the coating temperature higher than the normal temperature, and the properties of the hot melt composition change due to thermal degradation, and an unpleasant odor The problem is that the safety of the user is reduced. In addition, when the mold is poured into a mold and formed into a shape that conforms to the assembly member, there is a problem that molding defects are likely to occur because the melt viscosity is too high.

  Furthermore, although the resin composition of Patent Document 2 secures the sealability of the resin composition by containing bubbles, it can not be coated by a general-purpose (ordinary) hot melt applicator because it contains bubbles. , A dedicated hot melt applicator is required.

  As described above, although the melt viscosity is low to such an extent that automatic coating can be performed with a general-purpose hot melt applicator, and the moldability and releasability are high, the sealability is excellent and the liquid is softened. Hot melt compositions in which agent bleed out is suppressed have not been developed yet.

  Therefore, the present invention is excellent in sealability even though the melt viscosity is low enough to allow automatic application with a general-purpose hot melt applicator, and the moldability and releasability of the mold are high. An object of the present invention is to provide a hot melt composition in which bleed-out is suppressed and a sealing material using the same.

MEANS TO SOLVE THE PROBLEM As a result of earnestly research in order to solve the said subject, this inventor discovers that the said objective can be achieved according to the hot-melt composition containing the hydrogenated substance of a specific styrenic thermoplastic elastomer, and completes this invention. It reached.

That is, the present invention relates to the following hot melt composition and sealing material.
1. A hot melt composition comprising a styrenic block copolymer (A) and a liquid softener (B),
(1) The styrenic block copolymer (A) is a styrene-isoprene-styrene (SIS) copolymer, a styrene-butadiene-styrene (SBS) copolymer, and a styrene-isoprene / butadiene-styrene (SIBS) co-polymer. A hydrogenated product of at least one styrenic thermoplastic elastomer selected from the group consisting of polymers,
(2) The content of the liquid softener (B) is 150 to 450 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A),
(3) The hot melt composition has a viscosity ratio (η1 / η2) of 2 to 15 between the melt viscosity (η1) at 140 ° C. and the melt viscosity (η2) at 180 ° C., and the melt viscosity at 180 ° C. 2000 mPa · s or less,
Hot melt composition characterized in that.
2. The styrene-based block copolymer (A) is styrene-ethylene-butylene-styrene (SEBS) copolymer, styrene-ethylene-propylene-styrene (SEPS) copolymer, styrene-ethylene-ethylene-propylene-styrene ( The hot melt composition according to claim 1, which is at least one selected from the group consisting of SEEPS) copolymer and styrene-butylene-butadiene-styrene (SBBS) copolymer.
3. 3. The hot melt composition according to item 1 or 2, wherein the styrenic block copolymer (A) has a weight average molecular weight (Mw) of 20,000 to 100,000.
The hot melt composition according to any one of Items 1 to 3, wherein substantially no oil bleed is observed after 3 hours of aging in an environment of 4.23 ° C.
5. The sealing material which consists of a hot-melt composition in any one of said claim | item 1 -4.
6. 6. The sealing material according to the above item 5, which is used as a sealing material for industrial use at joints of various assembly members.

  The hot melt composition of the present invention has sealing properties (sealability) despite the fact that the melt viscosity is low enough to allow automatic application with a general-purpose hot melt applicator, and the moldability and releasability of the mold are high. It is excellent and the bleed out of the liquid softener is suppressed. Therefore, the hot melt composition of the present invention is useful as an industrial sealing material used for the joint of various assembly members.

The hot melt composition of the present invention is a hot melt composition containing a styrenic block copolymer (A) and a liquid softener (B),
(1) The styrenic block copolymer (A) is a styrene-isoprene-styrene (SIS) copolymer, a styrene-butadiene-styrene (SBS) copolymer, and a styrene-isoprene / butadiene-styrene (SIBS) co-polymer. A hydrogenated product of at least one styrenic thermoplastic elastomer selected from the group consisting of polymers,
(2) The content of the liquid softener (B) is 150 to 450 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A),
(3) The hot melt composition has a viscosity ratio (η1 / η2) of 2 to 15 between the melt viscosity (η1) at 140 ° C. and the melt viscosity (η2) at 180 ° C., and the melt viscosity at 180 ° C. 2000 mPa · s or less,
It is characterized by

The hot melt composition of the present invention having the above-mentioned characteristics has a low melt viscosity to the extent that it can be automatically applied by a general-purpose hot melt applicator, and has high sealability (due to high moldability and releasability of the mold). Sealability), and bleed out of the liquid softener is suppressed. Therefore, the hot melt composition of the present invention is useful as an industrial sealing material used for the joint of various assembly members.

  Hereinafter, each component which comprises the hot-melt composition of this invention is demonstrated.

Styrene-based block copolymer (A)
The styrene-based block copolymer (A) used in the present invention is a styrene-isoprene-styrene (SIS) copolymer, a styrene-butadiene-styrene (SBS) copolymer, and a styrene-isoprene / butadiene-styrene (SIBS) co-polymer. Hydrogenated products of at least one styrenic thermoplastic elastomer selected from the group consisting of polymers.

  The hydrogenation mode may be either complete hydrogenation (partial hydrogenation) or partial hydrogenation (partial hydrogenation). Specifically, as the hydrogenation agent, styrene-ethylene-butylene-styrene ( SEBS) from Styrene-Ethylene-Propylene-Styrene (SEPS) Copolymer, Styrene-Ethylene-Ethylene-Propylene-Styrene (SEEPS) Copolymer and Styrene-Butylene-Butadiene-Styrene (SBBS) Copolymer And at least one selected from the group consisting of In the present invention, among these hydrogenated substances, it is preferable to contain at least one selected from the group consisting of SEBS, SEPS and SEEPS as the styrene-based block copolymer (A).

  In particular, the SEBS is a fully hydrogenated SBS. The above SEPS is a fully hydrogenated SIS. SEEPS is a fully hydrogenated SIBS. Moreover, SBBS is a partial hydrogenated substance of SBS.

  As styrene content of a styrene system block copolymer (A), 10-40 mass% is preferable in 100 mass% of each styrene system block copolymer (hydrogenation thing), and 20-35 mass% is more preferable. When the styrene content is 40% by mass or less, the hot melt composition can be softened to exhibit better sealability, and when it is 10% by mass or more, appropriate flexibility can be maintained. It is possible to express better sealability.

  A commercially available product can be used as the SEBS copolymer. Examples of commercially available products include G1726 manufactured by Kraton Polymer, and G1650 manufactured by Kraton Polymer.

  A commercially available product can be used as the SEPS copolymer. As a commercial item, Kuraray SEPTON2063, Kuraray SEPTON 2005 etc. are mentioned, for example.

  A commercially available product can be used as the SEEPS copolymer. As a commercial item, Kuraray SEPTON 4033, Kuraray SEPTON 4055 etc. are mentioned, for example.

  The styrenic block copolymer (A) desirably has a weight average molecular weight (Mw) in the range of 20,000 to 200,000. If it is 20000 or more, the bleed out of the liquid softener (B) described later can be easily suppressed, and if it is 200,000 or less, good mold injectability can be maintained.

The "weight average molecular weight" in the present specification is a physical property value of a styrenic block copolymer measured by gel chromatography using a styrene calibration standard. In detail, the weight average molecular weight is a value measured by the following method. That is, the styrenic block copolymer (A) was dissolved in each of tetrahydroxyfuran (THF), and measurement was performed using APC (manufactured by Nippon Waters Co., Ltd.) equilibrated in advance using THF.

Liquid softener (B)
The hot melt composition of the present invention contains a liquid softener (B).

  The liquid softener (B) is not particularly limited, and examples thereof include paraffinic process oil, naphthenic process oil, aromatic process oil, liquid paraffin, synthetic hydrocarbon oil and the like. Among these liquid softeners, paraffinic process oil, naphthenic process oil, liquid paraffin, and hydrocarbon synthetic oil are preferable, and paraffinic process oil, liquid paraffin, and hydrocarbon synthetic oil are more preferable.

  A commercial item can be used as paraffin type process oil. Examples of commercially available products include PW-32 manufactured by Idemitsu Kosan Co., Ltd., Diana Flecia S32 manufactured by Idemitsu Kosan Co., Ltd. and PS-32 manufactured by Idemitsu Kosan Co., Ltd.

  A commercial item can be used as a naphthenic process oil. Examples of commercially available products include Diana Fresiasiae N28 manufactured by Idemitsu Kosan Co., Ltd., Diana Flarescia U46 manufactured by Idemitsu Kosan Co., Ltd., Diana Process Oil NR manufactured by Idemitsu Kosan Co., Ltd., and the like.

  A commercial item can be used as liquid paraffin. Examples of commercially available products include P-100 manufactured by MORESCO, and Kaydol manufactured by Sonneborn.

  A commercial item can be used as a hydrocarbon synthetic oil. As a commercial item, Mitsui Chemicals Co., Ltd. Lucant HC-10, Mitsui Chemical Co. Lucant HC-20 etc. are mentioned, for example.

  The said liquid softener (B) may be used individually by 1 type, and may mix and use 2 or more types.

  The content of the liquid softener (B) in the hot melt composition of the present invention is preferably 150 to 450 parts by mass, more preferably 200 to 350 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A). preferable. When the content of the liquid softener (B) is 150 parts by mass or more, the melt viscosity of the hot melt composition is further reduced, and the mold injectability of the hot melt composition is further improved. When the content of the liquid softener (B) is 450 parts by mass or less, the bleed out of the liquid softener (B) can be further easily suppressed.

Optional Additives The hot melt composition of the present invention may contain any additive as long as the object of the present invention is not substantially impaired. As optional additives, tackifier resins, waxes, antioxidants, ultraviolet absorbers and the like can be mentioned.

As the tackifying resin, natural rosin, modified rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, copolymer of natural terpene, three-dimensional polymer of natural terpene, Hydrogenated derivatives of copolymers of natural terpenes, terpene resins, hydrogenated derivatives of phenolic modified terpene resins; petroleum resins such as C5 petroleum resins, C9 petroleum resins, C5 C9 petroleum resins, and hydrogen added to these petroleum resins Partially hydrogenated petroleum resin, fully hydrogenated petroleum resin, and the like.

  C5 petroleum resin is a petroleum resin made from C5 fraction of petroleum, C9 petroleum resin is a petroleum resin made from C9 fraction of petroleum, C5C9 petroleum resin is a C5 fraction of petroleum It is petroleum resin which used C9 and C9 fraction as a raw material. Examples of the C5 fraction include cyclopentadiene, isoprene, pentane and the like. Examples of the C9 fraction include styrene, vinyl toluene, and indene. As the C5 petroleum resin and the C5C9 petroleum resin, those containing dicyclopentadiene (DCPD) derived from cyclopentadiene which is one of C5 fractions in a skeleton are preferable.

  As the tackifying resin, petroleum resins, partially hydrogenated petroleum resins, and fully hydrogenated petroleum resins are preferable in that they are excellent in odor control, thermal stability and the like of the hot melt composition, and partially hydrogenated petroleum resins, and Fully hydrogenated petroleum resins are more preferred. The tackifier resin may be used alone or in combination of two or more.

  The wax is not particularly limited. For example, animal-based waxes such as shell wax and beeswax; plant-based waxes such as carnauba wax and wexer wax; mineral-based waxes such as paraffin wax and macrocrystallin wax; Fischer Tropsch wax, ethylene -Synthetic waxes such as polyolefin waxes including vinyl acetate copolymer (EVA) waxes, etc. may be mentioned. Among them, polyolefin-based waxes are preferable in that the thermal stability of the hot melt composition can be further suppressed from being reduced and the generation of odor can be further reduced. The waxes may be used alone or in combination of two or more.

  A commercial item can be used as a wax. Examples of commercially available polyolefin-based waxes include A-C7 manufactured by Honeywell, VISCOWAX 122 manufactured by INNOSPEC, and commercially available products of ethylene-vinyl acetate copolymer (EVA) -based waxes include A-C400 manufactured by Honeywell, and INNOSPEC VISCOWAX334 manufactured by Tokushu K.K.

  As the antioxidant, 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate, 2, 2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 2,4-bis (octylthiomethyl) -o-cresol, 2 -Tert-Butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-tert-amyl-6- [1- (3,5) -Di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate, 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl)] acrylate, tetrakis [methylene Hindered phenolic antioxidants such as 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane; dilauryl thiodipropionate, lauryl stearyl thiodipropionate, pentaerythritol tetrakis (3 Sulfur based antioxidants such as lauryl thiopropionate); phosphorus based antioxidants such as tris (nonylphenyl) phosphite and tris (2,4-di-t-butylphenyl) phosphite and the like. The antioxidant may be used alone or in combination of two or more.

As a UV absorber, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl) benzotriazole, 2- (2 ′ Benzotriazole-based ultraviolet absorbers such as -hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole; benzophenone-based ultraviolet absorbers such as 2-hydroxy-4-methoxybenzophenone; salicylic acid ester-based UV absorbers; cyanoacrylate UV absorbers; hindered amine light stabilizers. The ultraviolet absorber may be used alone or in combination of two or more.

  The total content of the optional additives in the hot melt composition of the present invention is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A). 10 parts by mass is more preferable. By making the total content of the above optional additives into the above range, the hot melt composition of the present invention has a further excellent mold injectability, in addition to the expression of the desired effect by the inclusion of the additives. Releasability, bleed-out resistance of a liquid softener, sealability are easily exhibited, and further excellent thermal stability and coating suitability are easily exhibited. In addition, it is preferable that the hot-melt composition of this invention does not contain tackifying resin among the said arbitrary additives in a suitable aspect, and when it contains, it is based on 100 mass parts of styrene system block copolymers (A). Preferably, the content is 10 parts by mass or less.

Physical Properties of Hot Melt Composition of the Present Invention The hot melt composition of the present invention has a viscosity ratio (η1 / η2) of 2 to 15 between the melt viscosity (η1) at 140 ° C. and the melt viscosity (η2) at 180 ° C. .

  When η1 / η2 is 2 or more, bleed-out of the liquid softener can be easily suppressed, and when 1/1 / η2 is 15 or less, good mold injectability can be easily maintained. Although η1 / η2 may be 2 to 15, 3 to 7 is particularly preferable.

  As used herein, "melt viscosity" is the viscosity of a hot melt composition that has become heat melted at a constant temperature. Moreover, ratio ((eta) 1 / (eta) 2) of melt viscosity ((eta) 1) in 140 degreeC and melt viscosity ((eta) 2) in 180 degreeC is a value measured by the following measuring methods. That is, the hot melt composition is heated and melted, and the viscosities in the molten state at 140 ° C. and 180 ° C. are measured using a Brookfield RVT viscometer (spindle No. 21) to obtain η 1 and η 2 respectively, 140 ° C. and 180 ° It is a value measured by calculating the ratio (η1 / η2) of melt viscosity at ° C.

  The hot melt composition of the present invention has a melt viscosity (η2) at 180 ° C. of 2000 mPa · s or less. When η2 exceeds 2000 mPa · s, the application suitability of the hot melt composition of the present invention using the hot melt applicator is reduced. 1500 mPa * s or less is preferable and 1000 mPa * s or less is more preferable. By setting η2 in the above range, the hot melt composition of the present invention is further excellent in coating suitability, and the value of 1/1 / η2 can be easily adjusted by the range of 2 to 15.

  The melt viscosity (η1) at 140 ° C. is preferably 25000 mPa · s or less, more preferably 10000 mPa · s or less. By setting η1 in the above range, the hot melt composition of the present invention is further excellent in coating suitability, and the value of 1/1 / η2 can be easily adjusted by 2 to 15.

  The coating method of the hot melt composition in the molten state is not particularly limited, and a method of forming a sealing material by bead coating using a robot (general-purpose hot melt applicator) in a groove of an assembly member or injection into a mold Etc. In particular, a method of injecting into a mold is suitable for forming a complicated seal member. In the embodiment of the present invention, in addition to the embodiment in which mold injection is performed after mold molding and the sealing material as a molded body is taken out, the mold shape at the desired seal portion of the assembly member The lid is placed, the hot melt composition is injected from the inlet provided to the lid to form the seal material at the desired site, and then the lid is removed, both of the embodiments not assuming mold release are mentioned. Be

  When the hot melt composition of the present invention is applied in a molten state, the coating temperature is preferably about 120 to 180 ° C, and more preferably about 140 to 160 ° C. When the coating temperature is 180 ° C. or less, it is easy to ensure coating aptitude by a general-purpose hot melt applicator while suppressing thermal deterioration of the hot melt composition. When the application temperature is 120 ° C. or more, moldability and releasability of the mold can be maintained well.

  Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples. However, the present invention is not limited to the description of the examples.

The raw materials used in Examples and Comparative Examples are as follows.
«Styrene-based block copolymer (A)»
Styrene-based block copolymer (A1):
Styrene-Ethylene-Butylene-Styrene (SEBS) Copolymer "G1726" manufactured by Kraton Polymers (Styrene content 30% by mass, Mw 31300)
Styrene-based block copolymer (A2):
Styrene-Ethylene-Butylene-Styrene (SEBS) Copolymer "G1652" manufactured by Kraton Polymers (Styrene content: 30% by mass, Mw 62600)
Styrene-based block copolymer (A3):
Styrene-Ethylene-Propylene-Styrene (SEPS) Copolymer "SEPTON 2063" manufactured by Kuraray Co., Ltd. (styrene content: 13% by mass, Mw: 178400)
Styrene block copolymer (A4):
Styrene-Ethylene-Ethylene-Propylene-Styrene (SEEPS) Copolymer "SEPTON 4033" manufactured by Kuraray Co., Ltd. (Styrene content: 30 mass%, Mw 77100)
Styrene-based block copolymer (A5; comparative product):
Styrene-Isoprene-Styrene (SIS) Copolymer "D1161" manufactured by Kraton Polymers (Styrene content 15% by mass, Mw 201500)
Styrene-based block copolymer (A6; comparative product):
Styrene-Butadiene-Styrene (SBS) Copolymer "Asaprene T-438" manufactured by Asahi Kasei Corporation (styrene content 35 mass%, Mw 57200)
Styrene-based block copolymer (A7):
Styrene-Ethylene-Butylene-Styrene (SEBS) Copolymer "Afee Kasei Corporation Tuftec H1517" (Styrene content 43% by mass, Mw 76300)
Styrene-based block copolymer (A8):
Styrene-Ethylene-Butylene-Styrene (SEBS) Copolymer "Afee Kasei Co., Ltd. Tuftec H1043" (Styrene content: 67% by mass, Mw 47500)

«Liquid plasticizer (B)»
-Paraffinic process oil (B1): "PW-32" manufactured by Idemitsu Kosan Co., Ltd.
・ Naphthene process oil (B2): Idemitsu Kosan "N-90"

«Antioxidants:»
・ Phenolic Antioxidant BASF "IRGANOX1010"

Examples 1 to 7 and Comparative Examples 1 to 6
The raw materials described above were introduced into the stirring kneader equipped with a heating device at the amounts shown in Table 1, respectively. A hot melt composition was produced by kneading while heating at 145 ° C. for 90 minutes.

The properties of each hot melt composition were evaluated under the following measurement conditions.
(Melt viscosity)
The hot melt composition was heated and melted, and the viscosities in the molten state at 140 ° C. and 180 ° C. were measured using a Brookfield RVT viscometer (spindle No. 21), and were respectively defined as η1 and η2. Further, based on the measurement results, the ratio η1 / η2 of the melt viscosity at 140 ° C. and 180 ° C. was calculated. As the value of 金 1 / η2 is closer to 2, it can be evaluated that the mold injectability is excellent.

(Automatic application)
Using a nozzle diameter of 1 mm or a nozzle diameter of 12/1000 mm, the hot melt composition is applied to a bead shape by using a nozzle diameter of 1 mm or a nozzle diameter of 12/1000 mm in a Nordson hot melt applicator whose temperature is adjusted to 180 ° C. I worked.

The appearance of the coated bead-like hot melt was visually observed, and the state of pulsation was evaluated according to the following evaluation criteria. If the evaluation is 評 価 or more, it can be evaluated that there is no problem in actual use.
:: No pulsation 極: Extremely observed pulsation Δ: Slight pulsation observed ×: Always observed pulsation or no coating.

(Mold injection)
The hot melt composition is injected into the mold at a coating temperature of 180 ° C., from the injection port formed on the side in a mold having 45 mm square grooves, using a 1.5 mm diameter nozzle, and the following evaluation Evaluated according to the criteria. If the evaluation is 評 価 or more, it can be evaluated that there is no problem in actual use.
◎: injection complete in 0.7 seconds or less ○: injection complete in 1 second or less Δ: injection complete in 1 to 1.5 seconds ×: injection complete in 2 seconds or more.

(Mold release property)
The mold is applied by applying the hot melt composition at a coating temperature of 180 ° C., using a 1.5 mm diameter nozzle for 2 seconds or more from an injection port made on the side to a mold having 45 mm square grooves at a coating temperature of 180 ° C. Was injected.

  After the injected hot melt composition was cured, the mold lid was removed, and the mold releasability at the time of removing the hot melt seal member from the mold was evaluated.

The evaluation criteria for mold releasability are as follows. In addition, if it is (circle) or (triangle | delta), it can be evaluated that there is no problem in actual use.
Good: The hot melt seal member does not remain in the mold. Δ: The hot melt seal member slightly remains in the mold. X: The hot melt seal member remains in the mold and is torn off.

(Sealing)
The molded product of the hot melt composition prepared by the above mold injectability was placed on a glass plate and aged for 30 minutes, then water was poured into the space surrounded by the hot melt composition and aged for 30 minutes. The results were evaluated according to the following evaluation criteria.
○: Water did not flow out of the space enclosed by the hot melt composition.
Δ: Water did not flow out of the space enclosed by the hot melt composition, but slight penetration of water was observed in the gap between the hot melt composition and the glass plate.
X: Water flowed out of the space enclosed by the hot melt composition.

(Bleed-out resistance of liquid softener)
The molded product of the hot melt composition prepared by the above mold injectability was placed on wood free paper and cured for 3 hours under a 23 ° C. environment. The results were visually evaluated according to the following evaluation criteria.
◎: There is no bleeding due to the liquid softener bled out.
○: Bleeding due to liquid softener bled out is slight.
Fair: Bleeding due to liquid softener bled out below the shape of the molding of the hot melt composition.
X: Bleeding due to liquid softener bled out in the range of the shape of the molding of the hot melt composition or more.

  The results are shown in Table 1.

Claims (6)

A hot melt composition comprising a styrenic block copolymer (A) and a liquid softener (B),
(1) The styrenic block copolymer (A) is a styrene-isoprene-styrene (SIS) copolymer, a styrene-butadiene-styrene (SBS) copolymer, and a styrene-isoprene / butadiene-styrene (SIBS) co-polymer. A hydrogenated product of at least one styrenic thermoplastic elastomer selected from the group consisting of polymers,
(2) The content of the liquid softener (B) is 150 to 450 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A),
(3) The hot melt composition has a viscosity ratio (η1 / η2) of 2 to 15 between the melt viscosity (η1) at 140 ° C. and the melt viscosity (η2) at 180 ° C., and the melt viscosity at 180 ° C. 2000 mPa · s or less,
Hot melt composition characterized in that.   The styrene-based block copolymer (A) is styrene-ethylene-butylene-styrene (SEBS) copolymer, styrene-ethylene-propylene-styrene (SEPS) copolymer, styrene-ethylene-ethylene-propylene-styrene ( The hot melt composition according to claim 1, which is at least one selected from the group consisting of SEEPS) copolymers and styrene-butylene-butadiene-styrene (SBBS) copolymers.   The hot melt composition according to claim 1 or 2, wherein the styrenic block copolymer (A) has a weight average molecular weight (Mw) of 20,000 to 100,000.   The hot melt composition according to any one of claims 1 to 3, wherein substantially no oil bleed is observed after aging for 3 hours in a 23 ° C environment.   The sealing material which consists of a hot-melt composition in any one of Claims 1-4.   The sealing material according to claim 5, which is used as a seal for industrial use at a joint of various assembly members.