Hot melt composition

Abstract

To provide a hot-melt composition excellent in compatibility between low-temperature flexibility and heat resistance.SOLUTION: A thermoplastic block copolymer (A), a tackifier resin (B), and a softener (C), wherein the thermoplastic block copolymer (A) comprises a polymer block (a) comprising a structural unit derived from an aromatic vinyl compound and a polymer block (b) comprising a structural unit derived from a conjugated diene compound, and the softener (C) has a kinematic viscosity at 40°C of 450mm2 / s or less, and 35 to 200 parts by mass of the softener (C) based on 100 parts by mass of the thermoplastic block copolymer (A), the softener (C) having a weight average molecular weight of more than 500.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Hot melt adhesives are non-solvent adhesives that are used for adhesive purposes in a wide range of fields, including hygiene, bookbinding, packaging, construction, electricity, filters, and vehicles. In recent years, as products have become more highly value-added, there has been a demand for adhesive properties that can be applied to a variety of substrates and that can withstand a wide range of temperature environments.

[0002] Examples of indicators of the initial adhesive strength of adhesives include tackiness as typified by ball tack tests and loop tack tests, and flexibility as measured by tensile strength tests and compressive stress tests as indicators of ease of processing and sealing properties.

[0003] Patent Document 1 describes an invention relating to a hot melt composition containing a styrene-farnesene block copolymer (A), a tackifier (B), and a softener (C). The hot melt composition of Patent Document 1 is shown to have high workability, excellent initial adhesion, high adhesive strength, and reduced bleeding of oil and fat components.

[0004] Furthermore, Patent Document 2 describes an invention relating to a hot melt adhesive composition comprising a base polymer containing a styrene-based block copolymer, a tackifier, and a softener. It is shown that the hot melt adhesive composition of Patent Document 2 can provide sufficient adhesion to materials with many irregularities. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-162607 [Patent Document 2] Patent No. 7271681 Summary of the Invention [Problem to be solved by the invention]

[0006] The tackiness and flexibility mentioned above tend to decrease as the ambient temperature decreases. On the other hand, when the constituent materials or their blending ratios are changed to improve low-temperature performance, the heat-resistant shear strength, which is an index of heat resistance, tends to decrease significantly.

[0007] However, the properties of the hot melt composition described in Patent Document 1 are only those under room temperature conditions, and the wide range of raw materials listed is such that depending on the types of materials selected and their composition ratios, the composition may not be able to adequately maintain performance under a wide range of temperature conditions, raising concerns about tackiness and flexibility, particularly at low temperatures.

[0008] Furthermore, although the softener described in Patent Document 2 has a limited range of kinematic viscosity at 40°C, there is no suggestion of a relationship between kinematic viscosity and low-temperature flexibility. Furthermore, the test temperature exemplified in the holding power test in the examples is 40°C, and therefore the heat resistance of the hot melt adhesive is not evaluated at all under test conditions above 40°C, for example, at 70°C or higher.

[0009] As such, because hot melt adhesives are primarily made from thermoplastic resins, their performance varies depending on temperature. Achieving consistent performance in both low-temperature environments (below 0°C) and high-temperature environments (above 60°C) has been a particular challenge.

[0010] An object of the present invention is to provide a hot melt composition that is excellent in both flexibility in low-temperature environments and heat resistance in high-temperature environments. [Means for solving the problem]

[0011] The present inventors have discovered that a hot melt composition can be provided that can achieve both low-temperature flexibility and heat resistance by blending a thermoplastic block copolymer, a tackifier resin, and a softener in a specified ratio, the softener having a kinematic viscosity at 40°C and a weight-average molecular weight both within specified ranges.

[0012] Thus, according to the present invention, the following inventions are provided. (1) A thermoplastic block copolymer (A), a tackifier resin (B), and a softener (C), wherein the thermoplastic block copolymer (A) comprises a polymer block (a) consisting of structural units derived from an aromatic vinyl compound and a polymer block (b) consisting of structural units derived from a conjugated diene compound, and the softener (C) has a kinematic viscosity of 450 mm at 40°C. 2 / s or less, and has a weight average molecular weight of more than 500, and contains 35 to 200 parts by mass of the softener (C) per 100 parts by mass of the thermoplastic block copolymer (A). (2) The hot melt composition according to (1), which contains 35 to 200 parts by mass of the tackifier resin (B) per 100 parts by mass of the thermoplastic block copolymer (A). (3) The hot melt composition according to (1) or (2), wherein the content of structural units derived from an aromatic vinyl compound in the thermoplastic block copolymer (A) is 10% to 50%, and the aromatic vinyl compound is at least one selected from styrene, α-methylstyrene, and 4-methylstyrene. (4) The hot melt composition according to any one of (1) to (3), wherein the thermoplastic block copolymer (A) has a weight average molecular weight of 50,000 to 500,000. (5) The hot melt composition according to any one of (1) to (4), wherein the softener (C) is composed of a saturated hydrocarbon and has a naphthene content of less than 45%. (6) The hot melt composition according to any one of (1) to (5), wherein the polymer block (b) comprises a hydrogenation product of a conjugated diene compound. (7) The hot melt composition according to (6), wherein the polymer block (b) comprises a hydrogenation product of farnesene. [Effects of the Invention]

[0013] According to the present invention, a hot melt composition can be obtained that is excellent in both flexibility in low-temperature environments and heat resistance in high-temperature environments. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art or those that are substantially the same.

[0015] <Thermoplastic block copolymer (A)> The thermoplastic block copolymer (A) is composed of a polymer block (a) consisting of structural units derived from an aromatic vinyl compound and a polymer block (b) consisting of structural units derived from a conjugated diene compound.

[0016] Examples of aromatic vinyl compound monomers that are constituent units of the polymer block (a) include styrene, α-methylstyrene, 4-methylstyrene, etc. Among these, styrene is the most preferred.

[0017] Examples of the conjugated diene compound monomer that is a constituent unit of the polymer block (b) include butadiene, isoprene, pentadiene, myrcene, farnesene, and the like, with farnesene being the most preferred.

[0018] The conjugated diene compound monomer, which is a constituent unit of the polymer block (b), is preferably a product in which some or all of the carbon-carbon double bonds have been hydrogenated from the viewpoint of heat stability, weather resistance, etc., and in terms of imparting flexibility, a hydrogenated product of farnesene is particularly preferred.

[0019] The thermoplastic block copolymer preferably contains 10 to 50 mass% of polymer block (a) and 90 to 50 mass% of polymer block (b) in order to balance flexibility, heat resistance, and workability, and it is particularly preferable that the proportion of polymer block (a) is 15 to 40 mass% and the proportion of polymer block (b) is 85 to 60 mass%.

[0020] The bonding form of polymer block (a) and polymer block (b) is not particularly limited, and can be any arrangement, such as linear, branched, radial, star-shaped, or a combination of two or more thereof. Particularly preferred structures include, for example, a diblock type (a)-(b), a triblock type (a)-(b)-(a), and combinations thereof. Furthermore, when polymer block (a) is disposed at both ends of the structure, the two usually have approximately the same molecular weight, but they do not necessarily have to be the same.

[0021] The thermoplastic block copolymer used as component (A) may be a single resin, or may be a mixture of two or more resins as required.

[0022] The thermoplastic block copolymer (A) is not particularly limited, but is preferably a styrene-based thermoplastic block copolymer, and examples thereof include the SIS series manufactured by JSR Corporation, the Septon series and Septon BIO series manufactured by Kuraray Co., Ltd., the Kraton series manufactured by Kraton Corporation, and the Quintac series manufactured by Zeon Corporation. Specific examples include JSR SIS5229P, 5403P, 5506P, 5250P, 5002P, Septon 1020, 2002, 2004F, 2005, 2006, 2063, 2104, 4033, 4044, 4055, 4077, 4099, 8004, 8006, 8007L, Septon BIO SF902, SF903, SF904, Clayton K1633, K1640, G1641, G1642, G1643, G1645, G1646, and Quintac 3440, 3620, 3421, 3520, 3433N, 3450, 3280, and 3290.

[0023] <Tackifying resin (B)> In the present invention, a tackifying resin is contained as component (B) to impart adhesiveness and cohesiveness, adjust melt viscosity, etc. The type of tackifying resin may be selected from, for example, aromatic petroleum resins, aliphatic petroleum resins, alicyclic petroleum resins, rosin-based resins, terpene-based resins, copolymer resins thereof, and modified products thereof, which are typically used in hot melt compositions.

[0024] The softening point of the tackifier resin used as component (B) is preferably 80 to 160° C., more preferably 90 to 150° C. If the softening point is below the lower limit, heat resistance becomes insufficient, and conversely, if it is above the upper limit, low-temperature flexibility is lost.

[0025] The tackifying resin used as component (B) is preferably a tackifying resin in which some or all of the carbon-carbon double bonds have been hydrogenated in order to maintain the color of the hot melt composition and the color after heating at high temperatures.

[0026] The tackifying resin used as component (B) may be a single resin, or may be a combination of two or more resins as needed. The amount of tackifying resin to be added is 35 to 200 parts by mass, preferably 50 to 185 parts by mass, per 100 parts by mass of thermoplastic block copolymer component (A). If the amount of tackifying resin added exceeds this range, the hot melt composition will lose its low-temperature flexibility, and if it is below this range, it will lose its heat resistance.

[0027] Specific examples of component (B) include, but are not limited to, rosin-based resins and terpene-based resins from Yasuhara Chemical Co., Ltd., Arakawa Chemical Co., Ltd., Kraton Corporation, Harima Chemicals, Eastman Chemical Co., Ltd., and the like, and petroleum-based resins from ENEOS Corporation, Zeon Corporation, Tosoh Corporation, Exxon Corporation, Eastman Chemical Co., Toho Chemical Co., Ltd., Arakawa Chemical Co., Ltd., Mitsui Chemicals, Inc., Idemitsu Kosan Co., Ltd., and the like. Examples include the T-REZ series from ENEOS Corporation, the Quinton series from Zeon Corporation, the Petcol series and Petrotac series from Tosoh Corporation, the ECR series from Exxon Corporation, the Rigalite series and Endex series from Eastman Chemical Co., the Hi-Resin series from Toho Chemical Co., Ltd., the Arcon series from Arakawa Chemical Co., Ltd., the FTR series and FMR series from Mitsui Chemicals, and the Imave series from Idemitsu Kosan Co., Ltd.

[0028] <Softener (C)> In the present invention, a softener is contained as component (C) in order to adjust the melt viscosity and impart low-temperature flexibility.

[0029] The softener used as component (C) has a kinematic viscosity of 450mJ at 40°C as measured by ASTM D445 standard or a method equivalent thereto. 2 / s or less, and the weight average molecular weight calculated as a standard polystyrene equivalent based on measurements obtained by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent must be greater than 500.

[0030] The kinematic viscosity at 40°C is preferably 400m 2 / s or less, preferably 350 mm 2 / s or less, more preferably 150 mm 2 / s or less, particularly preferably 100 mm 2 / s or less, and the weight average molecular weight is preferably greater than 600, more preferably greater than 700.

[0031] When the kinematic viscosity falls within the above range, the hot melt composition has good low-temperature flexibility, and when the weight-average molecular weight falls within the above range, the hot melt composition has good heat resistance. By using a softener that satisfies both of these requirements, it is possible to achieve both low-temperature flexibility and heat resistance.

[0032] If the softener used as component (C) is a mineral oil, the naphthene content determined by ring analysis (NDM method) is preferably less than 45%, more preferably less than 40%, and even more preferably less than 35%. If the naphthene content is within the above range, the heat resistance of the hot melt composition tends to be improved.

[0033] The softener used as component (C) preferably has a pour point of 0° C. or lower, and more preferably -10° C. or lower. If the pour point is within the above range, low-temperature flexibility and low-temperature adhesiveness tend to be improved.

[0034] The softener used as component (C) is not particularly limited as long as it has a kinematic viscosity and weight-average molecular weight within the above-mentioned ranges, but from the viewpoint of heat resistance, weather resistance, etc., it is preferable to use a saturated hydrocarbon-based softener that does not contain carbon-carbon double bonds such as aromatics in its constituent components. Specific examples include hydrocarbon process oils; liquid polymers such as liquid polybutene, liquid polybutadiene, and liquid polyisoprene; and hydrocarbon oils such as liquid paraffin and olefin process oil.

[0035] The softener used as component (C) may be a single compound, or, if necessary, a combination of two or more compounds. The amount of softener is 35 to 200 parts by mass, preferably 50 to 185 parts by mass, per 100 parts by mass of thermoplastic block copolymer component (A). If the amount of softener is below this range, low-temperature flexibility and workability will be lost, while if it is below this range, heat resistance will be lost. A softener component having at least one of the kinematic viscosity at 40°C and the weight-average molecular weight outside the above ranges may be included. From the viewpoint of low-temperature flexibility and heat resistance, the amount of the softener component is preferably 50% by weight or less, more preferably 40% by weight or less, even more preferably 30% by weight or less, particularly preferably 10% by weight or less, and most preferably 5% by weight or less, of the total weight of the softener components contained in the composition.

[0036] Specific examples of component (C) include, but are not limited to, the Diana Process Oil series and Polybutene series from Idemitsu Kosan Co., Ltd., the VIVA-B-FIX series and PIONIER series from H&R Corporation, the SpectraSyn series from ExxonMobil Corporation, the Hicol series from Kaneda Corporation, and the Lucant series from Mitsui Chemicals Inc. In particular, the VIVA-B-FIX series is most highly valued from the perspective of adding low-temperature flexibility.

[0037] <Combined ingredient (D)> In the present invention, in addition to the above components, compounding agent component (D) such as an antioxidant, an ultraviolet absorber, an ultraviolet stabilizer, a filler, a silane coupling agent, a colorant (pigment, dye), an antistatic agent, a flame retardant, a solvent, or an antifoaming agent, which are commonly used in the technical field of hot melt compositions using a thermoplastic styrene elastomer as a base polymer, may be compounded as needed within a range that does not impair the object of the present invention.

[0038] Examples of primary antioxidants used in compounding agent component (D) include naphthylamine-based, p-phenylenediamine-based, quinoline-based, phenol-based, hindered phenol-based, and hindered amine-based antioxidants, with hindered phenol-based antioxidants being preferred. Examples of secondary antioxidants include phosphites, thioethers, and hydroxylamines, with phosphites being preferred. From the viewpoints of antioxidant effect and thermal stability of the composition, the content of the primary antioxidant and secondary antioxidant is preferably 0.5 to 5 parts by mass per 100 parts by mass of thermoplastic block copolymer component (A).

[0039] Examples of UV absorbers include benzotriazoles, triazines, benzophenones, and cyanoacrylates, with benzotriazoles being preferred. From the viewpoint of weather resistance of the composition, the content of the UV absorber is preferably 0.5 to 5 parts by mass per 100 parts by mass of the thermoplastic block copolymer component (A). Fillers that have been conventionally known can be used, including inorganic or organic fillers of various shapes. Adding a filler can strengthen the cured product and, for example, provide excellent adhesion to mortar, metals, etc. Examples of inorganic fillers include calcium carbonate, zinc oxide, glass beads, titanium oxide, alumina, carbon black, clay, ferrite, talc, mica powder, aerosil, silica, and inorganic fibers such as glass fiber, as well as inorganic foams. Examples of organic fillers include powders of thermosetting resins such as epoxy resins, carbon fibers, synthetic fibers, and synthetic pulp.

[0040] Examples of silane coupling agents include trimethoxyvinylsilane and γ-glycidoxypropyltrimethoxysilane, and their incorporation improves adhesion to wet surfaces. Examples of pigments include inorganic pigments such as titanium oxide, zinc oxide, ultramarine, red iron oxide, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, and sulfate; and organic pigments such as Neozabon Black RE, Neo Black RE, Orasol Black CN, and Orasol Black Ba (all manufactured by Ciba-Geigy), and Spiron Blue 2BH (manufactured by Hodogaya Chemical Co., Ltd.), which can be used in appropriate combinations as needed.

[0041] Dyes such as black dyes, yellow dyes, red dyes, blue dyes, and brown dyes are appropriately selected and used depending on the color tone required for the product. Antistatic agents include hydrophilic compounds such as quaternary ammonium salts, polyglycols, and ethylene oxide derivatives. Flame retardants include chloroalkyl phosphates, dimethyl methyl phosphonates, bromine-phosphorus compounds, ammonium polyphosphates, neopentyl bromide polyethers, and brominated polyethers. UV stabilizers include fatty acid silyl esters and fatty acid amide trimethylsilyl compounds. Antifoaming agents include calcium oxide, magnesium oxide, and molecular sieves.

[0042] The method for producing the hot melt composition of the present invention is not particularly limited, and it can be produced by a conventionally known method. For example, the hot melt composition can be obtained by adding each component and any other components that are optionally blended to a heating and stirring device heated to a temperature close to the melting point of the components, and thoroughly melting and mixing them. Examples of the heating and stirring device include a Banbury mixer equipped with a heating device and a degassing device, a pressure kneader, a Henschel mixer, a Brabender kneader, and a disperser. The pressure inside the heating and stirring device can be reduced as needed. The obtained hot melt composition can be filled and stored, for example, in plastic trays, paper containers, pails, or drums. The shape of the hot melt composition is not particularly limited.

[0043] The substrates to which the hot melt composition of the present invention can be applied, i.e., adhesive members and adherends, are not particularly limited, and examples thereof include polyolefins such as polyethylene, polypropylene, polybutene, and polystyrene; engineering plastics such as polycarbonate, polyester, polyamide, and polyacetal; metals, glass, and rubber.

[0044] The hot melt composition of the present invention can be used, for example, in pressure-sensitive bonding of automobile and vehicle (bullet train and electric train) parts, building and woodworking parts, electronics parts, packaging materials, textile materials, sanitary materials, tapes, labels, etc. Applications for automobile-related parts include bonding of interior materials such as ceilings, doors, and seats, and bonding and sealing of exterior materials such as side moldings. Applications for building and woodworking parts include bonding of doors, access floors, multi-layer floors, furniture assembly, edge bonding, profile wrapping, etc. at construction sites and in the manufacturing of building materials in factories. Applications for electronics parts include the assembly of lampshades, speakers, etc.

[0045] The heat resistance of a hot-melt composition is evaluated by a shear holding strength test under high temperature conditions. When a 500 g load is dropped at a temperature rise rate of 0.5°C per minute, the drop temperature is desirably 70°C or higher, preferably 75°C or higher, and more preferably 80°C or higher.

[0046] The method for using the hot melt composition of the present invention is not particularly limited and may be carried out in a conventional manner. For example, the hot melt composition can be used as follows.

[0047] The hot melt composition is usually applied to the surface of a component automatically or manually using a heating and application device called an applicator. The heating and application device is a device that can suck up a fixed amount of molten hot melt composition using a gear pump or the like, and is used by heating the composition appropriately depending on the softening point of the hot melt composition. The shape of the hot melt composition to be applied is not particularly limited, but it is usually applied in the form of dots, lines, or surfaces.

[0048] Thus, the hot melt composition of the present invention can exhibit excellent performance in terms of low-temperature flexibility and heat resistance. [Example]

[0049] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified. The physical properties were evaluated as follows.

[0050] (1) Low temperature flexibility: The hot melt composition was processed into a 1 mm thick sheet using a heat press and molded into a strip with a short side of 10 mm and a long side of 60 mm, which was used as a test sample. After leaving it to stand for at least 1 hour in a vertical testing machine set at -20°C, both 20 mm long ends of the test sample were clamped with a jig, and the remaining 20 mm was used as the test part. The test sample was then pulled at a tensile speed of 300 mm / min to measure the strength at break (MPa). (2) Heat resistance: The hot-melt composition was processed into a 0.03 mm thick sheet using a heat press with a polyethylene terephthalate film (Lumirror, manufactured by Toray Industries, Inc.) as a support, and molded into a 25 mm x 25 mm size. This was used as a test sample (hot-melt sheet). The test sample was laminated to a stainless steel (SUS304) substrate with a bonding area of ​​25 mm x 25 mm, pressed back and forth 10 times with a 50 mm wide 2 kg roller, and left at room temperature for 15 hours. The SUS portion of the resulting test sample was fixed at the top end so that the test sample sagged in the shear direction. A 500 g weight was hung from the bottom end of the test sample and placed in a thermostatic chamber. The temperature was then increased at a rate of 0.5 °C / min, and the temperature in the thermostatic chamber at the time the weight fell was recorded as the heat-resistant retention temperature. The evaluation criteria according to the heat-resistant retention temperature are as follows. ○: 70℃ or higher ×: Less than 70℃

[0051] 100 parts of (A1) as a thermoplastic block copolymer, 75 parts of (B1) as a tackifying resin, and a kinematic viscosity of 450 mm 2 A hot melt composition containing 75 parts of a softener (C1) having a viscosity of 1 / s or less and a weight-average molecular weight of more than 500, and 2.5 parts of a hindered phenol-based antioxidant, "Irganox 1010 (manufactured by BASF)" (D1), was prepared by heating and mixing the components. The low-temperature flexibility and heat resistance of the resulting composition were measured. The results are shown in Table 1.

[0052] The materials used in Example 1 are as follows: (A1) Septon BIO SF904 (trade name, manufactured by Kuraray Co., Ltd., aromatic vinyl compound component 21%, weight average molecular weight 90,000) (B1) YS Resin PX1250 (trade name, manufactured by Yasuhara Chemical Co., Ltd., softening point 125°C) (C1) VIVA-B-FIX 10229 (trade name, manufactured by H&R, kinematic viscosity 21 mm at 40°C) 2 / s, weight average molecular weight 750) (D1) Irganox 1010 (trade name, manufactured by BASF, hindered phenol-based antioxidant)

[0053] Hot melt compositions were prepared in the same manner as in Example 1, except that the compositions of components (A) to (D) were changed to those shown in Table 1, and the resulting compositions were evaluated in the same manner as in Example 1. The results are shown in Table 1. In the results for low-temperature flexibility in Table 1, "cracked" indicates that the test sample cracked when placed in the vertical testing machine after standing at low temperature, and was therefore in no condition to be used for testing.

[0054] [Table 1]

[0055] The materials used in the above Examples 2 to 12 and Comparative Examples 1 to 8 are as follows. (A2) Quintac 3450 (trade name, manufactured by Zeon Corporation, aromatic vinyl compound component 19%, weight average molecular weight 280,000) (A3) Kraton G1726VS (trade name, manufactured by Kraton Corporation, aromatic vinyl compound component 30%, weight average molecular weight 66,000) (A4) Quintac 3421 (trade name, manufactured by Zeon Corporation, aromatic vinyl compound component 14%, weight average molecular weight 250,000) (A5) Quintac 3390 (trade name, manufactured by Zeon Corporation, aromatic vinyl compound component 48%, weight average molecular weight 170,000) (B2) Imarv P140 (trade name, manufactured by Idemitsu Kosan Co., Ltd., softening point 140°C) (B3) Alcon SM10 (trade name, manufactured by Arakawa Chemical Industries, Ltd., softening point 100°C) (B4) Escorez 5320 (trade name, manufactured by ExxonMobil Corporation, softening point 120°C) (C2) Diana Process Oil PW-380 (trade name, manufactured by Idemitsu Kosan Co., Ltd., kinematic viscosity 382 mmHg at 40°C) 2 / s, weight average molecular weight 1250, naphthene content 27%) (C3) SpectraSyn 10 (trade name, manufactured by Exxon Mobil Corporation, kinematic viscosity at 40°C 66 mmHg) 2 / s, weight average molecular weight 1400) (C4) VIVA-B-FIX 10227 (product name, manufactured by H&R, kinematic viscosity 58 mm at 40°C 2 / s, weight average molecular weight 1150) (C5) Hicol K-290 (trade name, manufactured by Kaneda Co., Ltd., kinematic viscosity 35 mm at 40°C) 2 / s, weight average molecular weight 500, naphthene content 30%) (C6) Diana Process Oil PW-32 (trade name, manufactured by Idemitsu Kosan Co., Ltd., kinematic viscosity 31 mm at 40°C) 2 / s, weight average molecular weight 450, naphthene content 33%) (C7) Polybutene 15H (trade name, manufactured by Idemitsu Kosan Co., Ltd., kinematic viscosity at 40°C: 550 mmH) 2 / s, weight average molecular weight 550) (C8) Diana Process Oil NS-100 (trade name, manufactured by Idemitsu Kosan Co., Ltd., kinematic viscosity 95 mm at 40°C) 2 / s, weight average molecular weight 400, naphthene content 34%)

[0056] The results of the examples show that a hot melt composition that exhibits excellent low-temperature flexibility and heat resistance can be provided by blending a thermoplastic block copolymer component (A) and a tackifier resin component (B) having aromatic vinyl compound component ratios within a predetermined range with a softener component (C) having a kinematic viscosity at 40°C and a weight-average molecular weight both within a predetermined range in a predetermined ratio. On the other hand, the results of the comparative examples show that when a softener component (C) having a kinematic viscosity at 40°C outside the predetermined range is used, the hot melt composition loses its low-temperature flexibility, and when a softener component (C) having a weight-average molecular weight outside the predetermined range is used, the hot melt composition loses its heat resistance. [Industrial Applicability]

[0057] According to the present invention, a hot melt composition is provided which has excellent compatibility between low-temperature flexibility and heat resistance, which are difficult to achieve at the same time, and which may be applicable to adhesive applications over a wide range of curing environmental temperatures.

Claims

1. The thermoplastic block copolymer (A) comprises a thermoplastic block copolymer (A), a tackifier resin (B), and a softener (C), wherein the thermoplastic block copolymer (A) comprises a polymer block (a) comprising structural units derived from an aromatic vinyl compound and a polymer block (b) comprising structural units derived from a conjugated diene compound, and the softener (C) has a kinematic viscosity of 450 mm at 40°C. 2 / s or less, and has a weight average molecular weight of more than 500, and the hot melt composition contains the softener (C) in an amount of 35 to 200 parts by mass per 100 parts by mass of the thermoplastic block copolymer (A).

2. 2. The hot melt composition according to claim 1, comprising 35 to 200 parts by mass of the tackifier resin (B) per 100 parts by mass of the block copolymer (A).

3. 3. The hot melt composition according to claim 1, wherein the content of an aromatic vinyl compound component in the thermoplastic block copolymer (A) is 10% to 50%, and the aromatic vinyl compound is at least one selected from styrene, α-methylstyrene, and 4-methylstyrene.

4. 3. The hot melt composition according to claim 1, wherein the thermoplastic block copolymer (A) has a weight average molecular weight of 50,000 to 500,000.

5. 3. The hot melt composition according to claim 1, wherein the softening agent (C) comprises a saturated hydrocarbon and has a naphthene content of less than 45%.

6. 3. The hot melt composition of claim 1, wherein the polymer block (b) comprises a hydrogenation product of a conjugated diene compound.

7. 7. The hot melt composition of claim 6, wherein the polymer block (b) comprises a hydrogenation product of farnesene.

Images