Hot-melt composition

Abstract

To provide a hot-melt composition which exhibits superior applicability due to suitable melt viscosity, demonstrates superior heat resistance due to suppression of degradation even under high-temperature melting, and achieves improved recyclability due to high tensile properties.SOLUTION: A hot-melt composition comprises (A) a styrene-based thermoplastic elastomer, (B) a tackifier, (C) a softener, and (D) silica-based particles. Preferably, the silica-based particles (D) are fumed silica.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a hot melt composition.

Background Art

[0002] Conventionally, extensive research and development has been conducted on hot melt compositions. Since hot melt compositions melt when heated and solidify when cooled to room temperature of about 23°C, they are suitably used as adhesives. Their features include being solvent-free, environmentally friendly, curable in a short time, and very easy to handle materials, and since they can improve the working environment at the manufacturing site, they are widely used in various fields.

[0003] In the past, the applicant of the present application invented a hot melt composition comprising a hydrogenated paraffinic process oil, a high molecular weight styrene-based block copolymer, a polyphenylene ether resin or a modified polyphenylene ether resin, a tackifying resin, and an antioxidant as essential components (Patent Document 1). This hot melt composition maintained high viscosity retention and tensile strength retention even after being placed at high temperature and had a disassembling property.

[0004] Furthermore, the applicant of the present application improved the above-described hot melt composition. Specifically, an easily disassembled hot melt composition characterized by containing a SEEPS block copolymer (A) having a weight average molecular weight of 150,000 or more, a paraffin oil (B) having a kinematic viscosity (40°C) of 100 to 1000 mm 2 / s, an aromatic petroleum resin (C) having a softening point of 100°C or higher, and a non-polar tackifier (D), and not containing polypropylene wax was invented (Patent Document 2). This hot melt composition had good adhesion and easy peelability to polypropylene resin, excellent elasticity of the composition itself, a small change rate of viscosity decrease even when left at a high temperature of 220°C, and sufficient heat resistance.

Prior Art Documents

Patent Documents

[0005] Patent Document 1 Japanese Patent Application Laid-Open No. 2004-189844 Patent Document 2 Japanese Patent Application Laid-Open No. 2017-179061

[0006] Conventionally, in the manufacturing process of vehicle parts, hot melt compositions have been preferably used. For example, in the case of a battery case which is a vehicle part, a hot melt composition is mainly used to fit and seal a main body case made of metal. Therefore, as the hot melt composition, it is required to have an appropriate melt viscosity for improving coating workability, and heat resistance such that it does not deteriorate even when it is in a high temperature state during running and does not flow out to the outside. Furthermore, in recent years, due to the need to recycle used products, the demand for the dismantlability of the sealed portion has increased, and since an improvement in tensile properties is also required so that the hot melt composition does not break finely even when force is applied to the sealed portion, there has been room for improvement. Summary of the Invention Problems to be Solved by the Invention

[0007] The problem to be solved by the present invention is to provide a hot melt composition which has excellent coating workability because of its appropriate melt viscosity, has good heat resistance because it can suppress deterioration even when melted at high temperature, and has improved recycling performance because of its high tensile properties. Means for Solving the Problems

[0008] The present invention is a hot melt composition characterized by containing a styrenic thermoplastic elastomer (A), a tackifier (B), a softening agent (C), and silica-based particles (D). Effects of the Invention

[0009] The hot-melt composition according to the present invention has an appropriate melt viscosity, so it has excellent coating workability, good heat resistance because deterioration can be suppressed even when melted at a high temperature, and high tensile properties, so there is an effect that the recycling performance is improved.

Mode for Carrying Out the Invention

[0010] <Styrenic thermoplastic elastomer> In the present invention, a styrenic thermoplastic elastomer (A) is used. The component (A) is used as a base polymer of the hot-melt composition according to the present invention.

[0011] Styrenic thermoplastic elastomers are mainly composed of a hard block derived from a styrenic compound and a soft block derived from a diene compound. As the bonding form of each block, there are linear, branched, and radial ones, but linear ones are relatively often provided.

[0012] Styrenic thermoplastic elastomers are divided into "unhydrogenated styrenic thermoplastic elastomers" in which the soft block is not hydrogenated and "hydrogenated styrenic thermoplastic elastomers" in which the soft block is hydrogenated. Examples of unhydrogenated styrenic block copolymers include styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SBS). Examples of hydrogenated styrenic block copolymers include styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), and styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS).

[0013] In the present invention, it is preferable to use a hydrogenated styrenic thermoplastic elastomer because of its high stability, and it is particularly preferable to use a styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS).

[0014] The toluene solution viscosity (30 °C, 5 wt%) of the component (A) is preferably 1 to 1000 mPa·s, more preferably 5 to 850 mPa·s, and particularly preferably 10 to 700 mPa·s.

[0015] Specific examples of the component (A) include Septon 4044 (trade name, manufactured by Kuraray Co., Ltd., styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS), toluene solution viscosity (30 °C, 5 wt%): 22 mPa·s), Septon 4055 (trade name, manufactured by Kuraray Co., Ltd., styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS), toluene solution viscosity (30 °C, 5 wt%): 90 mPa·s), Septon 4077 (trade name, manufactured by Kuraray Co., Ltd., styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS), toluene solution viscosity (30 °C, 5 wt%): 300 mPa·s), Septon 4099 (trade name, manufactured by Kuraray Co., Ltd., styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS), toluene solution viscosity (30 °C, 5 wt%): 670 mPa·s), and the like.

[0016] <Adhesion promoter> In the present invention, an adhesion promoter (B) is used. Examples of the type of the component (B) include terpene resins, terpene phenol resins, rosin resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, alicyclic hydrocarbon resins, and hydrogenated products or modified products thereof.

[0017] In the present invention, for example, an aromatic hydrocarbon resin (b1) can be used. By using the component (b1), the compatibility with the hard block derived from the styrene compound in the component (A) can be improved. Examples of the component (b1) include polymers of monomers having an aromatic ring such as styrene, α-methylstyrene, and vinyltoluene. However, in order to improve the stability in the high temperature region, it is particularly preferable to use a styrene-based adhesion promoter synthesized from styrene or α-methylstyrene.

[0018] Specific examples of the component (b1) include Plastolyn 290 (trade name, manufactured by Eastman, styrene-based, softening point: 140°C), Endex 155 (trade name, manufactured by Eastman, α-methylstyrene-based, softening point: 153°C), FMR 0150 (trade name, manufactured by Mitsui Chemicals, styrene-based, softening point: 145°C), FTR 2120 (trade name, manufactured by Mitsui Chemicals, styrene / α-methylstyrene copolymer-based, softening point: 125°C), and the like.

[0019] Also, within a range that does not impair the effects of the present invention, a tackifier (b2) other than the component (b1) can be used. Specific examples of the component (b2) include T-REZ HA125 (trade name, manufactured by ENEOS, hydrogenated alicyclic hydrocarbon resin, softening point: 120°C to 130°C), Eastotac H-142W (trade name, manufactured by Eastman, hydrogenated aliphatic hydrocarbon resin, softening point 142°C), and the like.

[0020] The softening point of the component (B) is preferably 60 to 250°C, more preferably 70 to 200°C, and particularly preferably 80 to 180°C.

[0021] The blending ratio of the component (B) is preferably 1 to 1000 parts by weight, more preferably 2 to 800 parts by weight, and particularly preferably 3 to 500 parts by weight with respect to 100 parts by weight in total of the above component (A).

[0022] When the components (b1) and (b2) are used in combination, the blending ratio is preferably 1:0.05 to 20, more preferably 1:0.1 to 10, and particularly preferably 1:0.3 to 3 in terms of weight ratio.

[0023] <Softening agent> In the present invention, a softening agent (C) is used. By using the component (C), the dispersibility of the above components (A) and (B) becomes good, so that the wettability of the adherend surface can be increased, and the adhesion between the layers can be improved.

[0024] As the component (C), it is preferably liquid at normal temperature (about 23°C). Examples of the type of the component (C) include paraffinic or naphthenic oils, liquid paraffin, polybutene, polyisobutylene, and liquid wax.

[0025] In the present invention, for example, a softening agent (c1) having a kinematic viscosity (at 40°C) of 200 to 1,500 mm 2 / s can be used. By using the component (c1), there is a tendency to easily adjust to an appropriate melt viscosity. The kinematic viscosity is preferably a measured value at 40°C according to JIS K 2283, and is 200 to 1,500 mm 2 / s, more preferably 250 to 1,000 mm 2 / s, and particularly preferably 300 to 800 mm 2 / s.

[0026] Specific examples of the component (c1) include Diana Process Oil PW-380 (trade name, manufactured by Idemitsu Kosan Co., Ltd., paraffinic oil, kinematic viscosity (at 40°C): 409 mm 2 / s), Nisseki Polybutene HV-15 (trade name, manufactured by ENEOS Corporation, polybutene, kinematic viscosity (at 40°C): 655 mm 2 / s), and the like.

[0027] Also, within a range not impairing the effects of the present invention, a softening agent (c2) having a kinematic viscosity (at 40°C) of less than 150 mm 2 / s can be used. Specific examples of the component (c2) include Diana Process Oil PW-90 (trade name, manufactured by Idemitsu Kosan Co., Ltd., paraffinic oil, kinematic viscosity (at 40°C): 91 mm 2 / s), Nisseki Polybutene LV-50 (trade name, manufactured by ENEOS Corporation, polybutene, kinematic viscosity (at 40°C): 110 mm 2 / s), and the like.

[0028] As the blending ratio of the component (C), it is preferably blended in an amount of 1 to 2,500 parts by weight, more preferably 50 to 2,000 parts by weight, and particularly preferably 100 to 1,500 parts by weight with respect to 100 parts by weight of the component (A).

[0029] When the components (c1) and (c2) are used in combination, the blending ratio is preferably 1:0.05 to 20, more preferably 1:0.1 to 10, and particularly preferably 1:0.3 to 5 in terms of weight ratio.

[0030] <Silica-based particles> In the present invention, silica-based particles (D) are used. Examples of the component (D) include amorphous silica which is relatively easily available. As amorphous silica, there are provided a large number of silica gels and precipitated silicas produced by a wet method, fumed silica produced by a dry method, etc. In particular, fumed silica can be preferably used because of its high stability and easy handling.

[0031] The inventor of the present invention has found that by using the component (D), the coating workability is excellent because the melt viscosity is appropriate, the heat resistance is good because deterioration can be suppressed even when melted at a high temperature, and the recycling performance is improved because the tensile properties are high, and thus the present invention has been completed. As factors contributing to such effects, the component (D) is composed of fine particles, has good dispersibility, and can maintain its dispersed state for a long period of time. In particular, in the case of fumed silica, it is presumed that it is related to the formation of a certain crosslinked structure due to the interaction on the particle surface.

[0032] As the blending ratio of the component (D), it is preferably blended in an amount of 0.01 to 100 parts by weight, more preferably 0.1 to 50 parts by weight, and particularly preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the component (A).

[0033] Specific examples of the (D) component include Rheoleasil PM-20L (trade name, manufactured by Tokuyama Corporation, fumed silica, hydrophobic, average primary particle diameter: 12 nm), Rheoleasil PM-09 (trade name, manufactured by Tokuyama Corporation, fumed silica, hydrophobic, average primary particle diameter: 22 nm), and the like.

[0034] In the present invention, various additives can be used. Examples of the types of additives include primary antioxidants, secondary antioxidants, light stabilizers, ultraviolet absorbers, and the like. As the primary antioxidant, hindered phenol-based compounds can be exemplified, and specific examples thereof include Irganox 1010 (trade name, manufactured by BASF). Further, as the secondary antioxidant, phosphite-based or thioether-based compounds can be exemplified, and specific examples thereof include Irgafos 168 (trade name, manufactured by BASF).

[0035] In addition, in the present invention, fillers such as calcium carbonate, talc, and clay, and various auxiliary agents such as preservatives and colorants may be included.

[0036] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these descriptions.

Examples

[0037] <Examples and Comparative Examples> In the formulations shown in Table 1, kneading was sufficiently performed using a kneader set at 190 °C to produce the hot melt compositions according to the Examples and Comparative Examples. Here, the numerical values in Table 1 represent parts by weight. The raw materials used are shown below. Septon 4055 (trade name, manufactured by Kuraray Co., Ltd., styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS), toluene solution viscosity (30 °C, 5 wt%): 90 mPa·s) Endex 155 (trade name, manufactured by Eastman Chemical Company, α-methylstyrene-based, softening point: 153 °C) T-REZ HA125 (trade name, manufactured by ENEOS, hydrogenated alicyclic hydrocarbon resin, softening point: 120°C to 130°C) Diana Process Oil PW-380 (trade name, manufactured by Idemitsu Kosan Co., Ltd., paraffinic oil, kinematic viscosity (40°C): 409 mm 2 / s) Diana Process Oil PW-90 (trade name, manufactured by Idemitsu Kosan Co., Ltd., paraffinic oil, kinematic viscosity (40°C): 91 mm 2 / s) Rheoleoseal PM-20L (trade name, manufactured by Tokuyama Corporation, fumed silica, hydrophobic, average primary particle size: 12 nm) Irganox 1010 (trade name, manufactured by BASF, primary antioxidant) Irgafos 168 (trade name, manufactured by BASF, secondary antioxidant) Asahi Thermal Carbon (trade name, manufactured by Asahi Carbon Co., Ltd., carbon black, colorant)

[0038]

Table 1

[0039] Regarding the hot melt compositions produced in the above examples and the like, various physical property evaluations were carried out in the following manner. The results are shown in Table 2.

[0040] <Melt Viscosity> The hot melt composition was placed in a cell heated to 210°C using a Brookfield BH type viscometer. After 20 minutes, the No. 29 spindle was inserted, and the spindle was rotated at 5 rpm. The value after another 20 minutes was taken as the melt viscosity (mPa·s).

[0041] <Tensile Strength> The hot melt composition was melted at 150°C and formed into a sheet with a thickness of 2 mm. It was left standing at a temperature of 23°C and a humidity of 50% for 24 hours to solidify. Then, it was cut into 10 mm × 50 mm and cured at a temperature of 23°C and a humidity of 50% for 24 hours to prepare test pieces. Subsequently, a tensile test was carried out at a tensile speed of 500 mm / min, and the strength at break was taken as the tensile strength (MPa).

[0042] <Heat resistance> The hot melt composition was melted at 150 °C, formed into a sheet with a thickness of 3 mm, allowed to stand at a temperature of 23 °C and a humidity of 50% for 24 hours, and then solidified. Then, it was cut into 10 mm × 50 mm and cured at a temperature of 23 °C and a humidity of 50% for 24 hours to prepare test pieces. Thereafter, the test pieces were placed still on a metal tray and left in a hot air dryer at 170 °C for 10 days. Those test pieces whose shapes did not completely collapse were evaluated as ○, and those whose shapes completely collapsed were evaluated as ×.

[0043]

Table 2

[0044] When the hot melt compositions according to the examples and comparative examples were produced, although the melt viscosities at 210 °C were comparable, the examples had better heat resistance because they could suppress deterioration even when melted at higher temperatures than the comparative examples, and had high tensile properties, so the recycling performance was improved.

Claims

1. A hot-melt composition comprising a styrene-based thermoplastic elastomer (A), a tackifier (B), a softening agent (C), and silica-based particles (D).

2. The hot-melt composition according to Claim 1, wherein the silica-based particles (D) are fumed silica.

3. The hot-melt composition according to Claim 1 or 2, which is used in the manufacture of vehicle parts.

4. An article coated with the hot-melt composition according to Claim 1 or 2.