Hot-melt composition and method for producing hot-melt composition

Abstract

The present invention addresses the problem of providing a hot-melt composition which exhibits excellent workability, which provides a cured product having a low compression set, and which exhibits excellent recoverability and a method which is for producing a hot-melt composition. The present invention relates to a hot-melt composition comprising a thermoplastic elastomer 1 which includes SEEPS having a weight-average molecular weight of not less than 300,000 and a styrene content of not less than 35 mass%, an aliphatic tackifying resin, a paraffin oil, and an antioxidant. The present invention also relates to a method for producing a hot-melt composition wherein: a thermoplastic elastomer 1, an aliphatic tackifying resin, a paraffin oil, and an antioxidant are mixed; and the thermoplastic elastomer 1 has a weight-average molecular weight of not less than 300,000 and a styrene content of 35-45 mass%.

Description

Description Title of invention: Hot melt composition and method for producing the same Technical field

[0001] The present invention relates to a hot melt composition and a method for producing the hot melt composition.

[0002] Hot melt compositions containing thermoplastic elastomers and the like have been used for bonding in automotive lighting fixtures and the like (for example, Patent Documents 1 and 2). Prior art documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-70344 Patent Document 2: Japanese Patent Application Laid-Open No. 2020-117661 Summary of the invention Problems to be solved by the invention

[0004] The present inventors have studied the hot melt compositions disclosed in Patent Documents 1 and 2 and have found that although the sealing materials obtained by curing the above hot melt compositions have excellent sealing properties due to their low compression set, the workability of the hot melt compositions when applied to a substrate may be poor.

[0005] Furthermore, when the hot melt composition is used for joining in an automotive lighting fixture, specifically, for example, the hot melt composition can be used as a sealant that joins (seals) the lens and housing of the automotive lighting fixture. By utilizing the easy dismantling property of the sealant, the automotive lighting fixture can be dismantled and the sealant recovered from the dismantled automotive lighting fixture. When recovering the sealant from the dismantled automotive lighting fixture, if the sealant can be recovered from the dismantled automotive lighting fixture in the form of, for example, a single linear bead, recovery of the sealant is facilitated. The present inventors have studied the recoverability of the hot melt compositions disclosed in Patent Documents 1 and 2 and have found that when a sealant obtained by curing the hot melt composition is recovered from a substrate, the sealant may be torn and difficult to recover, i.e., recoverability may be poor. [0006I] Therefore, an object of the present invention is to provide a hot melt composition that is easy to work with, has a low compression set in the cured product obtained, and is easy to recover. Another object of the present invention is to provide a method for producing the hot melt composition. Means for solving the above problems

[0007] As a result of intensive research into solving the above problems, the present inventors have found that the problems can be solved by the following configuration.

[0008]

[0001] A hot melt composition comprising a thermoplastic elastomer (1) containing SEEPS having a weight-average molecular weight of 300,000 or more and a styrene content of 35% by mass or more, an aliphatic tackifying resin, paraffin oil, and an antioxidant.

[0002] The hot melt composition according to

[0001] , wherein the thermoplastic elastomer 1 further contains a styrene-based thermoplastic elastomer 1-b having a weight average molecular weight of 200,000 or more and a styrene content of 30 mass% or less.

[0003] A hot melt composition according to

[0001] or

[0002] , wherein the weight average molecular weight of the thermoplastic elastomer 1 is 300,000 or more, and the styrene content of the thermoplastic elastomer 1 is 35% by mass or more.

[0004] A hot melt composition according to any one of

[0001] to

[0003] , wherein the aliphatic tackifying resin comprises a hydrogenated alicyclic tackifying resin.

[0005] A hot melt composition according to any one of

[0001] to

[0004] , which is used for an automobile lamp.

[0006] A thermoplastic elastomer 1 is mixed with an aliphatic tackifying resin, paraffin oil, and an antioxidant, and the weight average molecular weight of the thermoplastic elastomer 1 is 300,000 or more, and the styrene content of the thermoplastic elastomer 1 is 100% or more. A method for producing a hot melt composition, comprising producing a hot melt composition having a content of 35 to 45 mass%. [7] The method for producing a hot melt composition according to [6], wherein the thermoplastic elastomer 1 is a SEEPS having a weight average molecular weight of 300,000 or more and a styrene content of 35 mass% or more. [8 I A method for producing a hot melt composition according to [7], wherein the thermoplastic elastomer 1 further comprises a styrene-based thermoplastic elastomer 1-b having a weight-average molecular weight of 200,000 or more and a styrene content of 30 mass% or less. [9 I A method for producing a hot melt composition according to [6] or [7], wherein a hydrogenated alicyclic tackifying resin is used as the aliphatic tackifying resin. According to the present invention, there can be provided a hot melt composition which is excellent in workability, has a low compression set of the cured product obtained, and is excellent in recoverability. The present invention also provides a method for producing the hot melt composition.

[0010] The present invention will be described in detail below. The following explanation of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range including the numerical values ​​before and after "to" as the lower and upper limits. In this specification, when two or more types of a component are present, the "content" of that component means the total content of those two or more components, unless otherwise specified. In this specification, the method for producing a component is not particularly limited unless otherwise specified. For example, a conventionally known method can be used. In this specification, the hot melt composition of the present invention is characterized by its workability (hereinafter also referred to as "workability") and low compression set of the resulting cured product. The fact that at least one of the properties of the composition (hereinafter also referred to as "low compression set") and the recoverability (hereinafter also referred to as "recoverability") is superior is also referred to as "the effect of the present invention being superior." The same applies to the method for producing a hot melt composition of the present invention.

[0011] [Hot Melt Composition] First, the hot melt composition of the present invention (the composition of the present invention) will be described below. The composition of the present invention is a hot melt composition containing a thermoplastic elastomer 1 containing SEE PS having a weight-average molecular weight of 300,000 or more and a styrene content of 35 mass% or more, an aliphatic tackifying resin, paraffin oil, and an antioxidant.

[0012] [Thermoplastic Elastomer 1] In the composition of the present invention, thermoplastic elastomer 1 includes SEE PS having a weight-average molecular weight (Mw) of 300,000 or more and a styrene content (St amount) of 35 mass% or more. In this specification, the above SEE PS is also referred to as "styrene-based thermoplastic elastomer 1-a." In the present invention, a thermoplastic elastomer refers to a polymer that softens when heated and retains rubber elasticity when cooled. A styrene-based thermoplastic elastomer refers to a block copolymer having a polymer block having repeating units formed by styrene and / or a styrene derivative and a polymer block containing structural units derived from a conjugated diene. In the styrene-based thermoplastic elastomer, the structural units derived from the conjugated diene may be hydrogenated. The composition of the present invention contains the styrene-based thermoplastic elastomer 1-a. In other words, the styrene-based thermoplastic elastomer 1-a has the above-mentioned Mw and St amounts, and therefore has excellent workability, low compression set, and recoverability.

[0013] [Weight average molecular weight of styrene-based thermoplastic elastomer 1-a] In the composition of the present invention, the weight average molecular weight (Mw) of the styrene thermoplastic elastomer 1-a is 300,000 or more. The upper limit of the Mw of the styrene thermoplastic elastomer 1-a can be set to 600,000 or less. From the viewpoint of achieving superior effects of the present invention, the Mw of the styrene thermoplastic elastomer 1-a is preferably 330,000 or more, and more preferably 330,000 to 500,000.

[0014] (Method for measuring the weight-average molecular weight of styrene-based thermoplastic elastomer 1-a) In the present invention, the weight-average molecular weight of styrene-based thermoplastic elastomer 1-a refers to the weight-average molecular weight converted into standard polystyrene based on a value measured by gel permeation chromatography (GPC). The conditions for measuring the weight-average molecular weight of the styrene-based thermoplastic elastomer 1-a are as follows. The same applies to styrene-based thermoplastic elastomers other than styrene-based thermoplastic elastomer 1-a, and thermoplastic elastomer 1. (Measurement conditions) GPC: LCS solution (Shimazu) Detector: SPD-20A (Shimazu) Color A: Two AL P HA-5000 (Toso) connected in series Solvent: Tetrahydrofuran Temperature: 40 0 Flow rate: 0.5 m / min Concentration: 2 mg / ml Standard sample: polystyrene

[0015] [Styrene Content of Styrenic Thermoplastic Elastomer 1-a] In the composition of the present invention, the styrene content (St content) of the styrene thermoplastic elastomer 1-a is 35 mass% or more. In the present invention, the St content of the styrene thermoplastic elastomer is the ratio of the content of styrene repeating units in the styrene thermoplastic elastomer. When the styrene-based thermoplastic elastomer is styrene-based thermoplastic elastomer 1-a, the St content of styrene-based thermoplastic elastomer 1-a means the ratio of the content of repeating units of styrene in styrene-based thermoplastic elastomer 1-a. The upper limit of the St content of styrene-based thermoplastic elastomer 1-a can be set to 50% by mass or less. From the viewpoint of achieving better effects of the present invention, the St content of styrene-based thermoplastic elastomer 1-a is preferably 38% by mass or more, and more preferably 40% by mass or more.

[0016] (Method for measuring the styrene content of styrene-based thermoplastic elastomer 1-a) In the present invention, the styrene content of styrene-based thermoplastic elastomer 1-a can be measured by pyrolysis GC-MS (pyrolysis gas chromatography mass spectrometry). The same applies to styrene-based thermoplastic elastomers other than styrene-based thermoplastic elastomer 1-a, and thermoplastic elastomer 1. In the present invention, the styrene content (mass%) of a styrene-based thermoplastic elastomer may be the proportion of styrene and / or styrene derivatives in the total amount of monomers used in producing the styrene-based thermoplastic elastomer. For example, if the styrene-based thermoplastic elastomer is a commercially available product, the nominal value from its manufacturer may be used as the styrene content of the styrene-based thermoplastic elastomer. If the styrene-based thermoplastic elastomer is styrene-based thermoplastic elastomer 1-a, the styrene content (mass%) of styrene-based thermoplastic elastomer 1-a may be used as the proportion of styrene in the total amount of monomers used in producing the styrene-based thermoplastic elastomer 1-a. Furthermore, if styrene-based thermoplastic elastomer 1-a is a commercially available product, the nominal value from its manufacturer may be used as the styrene content of the styrene-based thermoplastic elastomer 1-a.

[0017] [ SEEPS ] In the present invention, the styrene-based thermoplastic elastomer 1-a is a styrene-ethylene-ethylene-propylene-styrene block copolymer (SEE-PS). Specific examples of the styrene-based thermoplastic elastomer 1-a include S Examples include hydrides of IS.

[0018] (Styrene-based thermoplastic elastomer 1-b) From the viewpoint of achieving better effects of the present invention, it is preferable that the thermoplastic elastomer 1 further contains a styrene-based thermoplastic elastomer 1-b having a weight-average molecular weight of 200,000 or more and a styrene content of 30 mass% or less.

[0019] (Weight-average molecular weight of styrene-based thermoplastic elastomer 1-b) The upper limit of the weight-average molecular weight (Mw) of the styrene-based thermoplastic elastomer 1-b can be set to 600,000 or less. From the viewpoint of achieving superior effects of the present invention, the Mw of the styrene-based thermoplastic elastomer 1-b is preferably 250,000 to 500,000, and more preferably 280,000 or more but less than 400,000.

[0020] (Styrene Content of Styrenic Thermoplastic Elastomer 1-b) The lower limit of the styrene content (St amount) of the styrene thermoplastic elastomer 1-b can be set to 10% by mass or more. From the viewpoint of achieving better effects of the present invention, the St amount of the styrene thermoplastic elastomer 1-b is preferably 20 to 30% by mass.

[0021] (Structure of styrene-based thermoplastic elastomer 1-b) Examples of the styrene-based thermoplastic elastomer 1-b include styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-butylene-styrene block copolymer (SEBS), and styrene-ethylene-ethylene-propylene-styrene block copolymer (SEE PS). From the viewpoint of obtaining superior effects of the present invention, it is preferable that the styrene-based thermoplastic elastomer 1-b contains a hydrogenated styrene-based thermoplastic elastomer. From the viewpoint of obtaining superior effects of the present invention, it is preferable that the styrene-based thermoplastic elastomer 1-b contains SEEPS. When the styrene-based thermoplastic elastomer 1-b contains SEEPS, for example, the SEEPS may be a hydrogenated product of SIS.

[0022] (Content of styrene-based thermoplastic elastomer 1-b) When thermoplastic elastomer 1 further contains styrene-based thermoplastic elastomer 1-b, the content of styrene-based thermoplastic elastomer 1-b is preferably more than 0% by mass and not more than 70% by mass, more preferably 40-60% by mass, of the total amount of thermoplastic elastomer 1, from the viewpoint of achieving a better effect of the present invention. (Content of styrene-based thermoplastic elastomer 1-a) In the present invention, the content of styrene-based thermoplastic elastomer 1-a can be more than 0% by mass and 100% by mass or less of the total amount of thermoplastic elastomer 1. Furthermore, when thermoplastic elastomer 1 further contains styrene-based thermoplastic elastomer 1-b, the content of styrene-based thermoplastic elastomer 1-a is preferably 30% by mass or more and less than 100% by mass, more preferably 40 to 60% by mass, of the total amount of thermoplastic elastomer 1, from the viewpoint of achieving a superior effect of the present invention and a high tensile elongation.

[0023] (Other styrene-based thermoplastic elastomers) The thermoplastic elastomer 1 may further contain a styrene-based thermoplastic elastomer (other styrene-based thermoplastic elastomer) other than the styrene-based thermoplastic elastomer 1-a and the styrene-based thermoplastic elastomer 1-b. The other styrene-based thermoplastic elastomer is not particularly limited. The thermoplastic elastomer 1 may be, for example, the styrene-based thermoplastic elastomer 1 Preferred embodiments include a case in which only styrene-based thermoplastic elastomer 1-a is contained, or a case in which only styrene-based thermoplastic elastomer 1-a and styrene-based thermoplastic elastomer 1-b are contained.

[0024] (Weight-average molecular weight and styrene content of thermoplastic elastomer 1) With regard to thermoplastic elastomer 1, from the viewpoint of achieving superior effects of the present invention, one preferred embodiment is one in which the weight-average molecular weight of thermoplastic elastomer 1 is 300,000 or more and the styrene content of thermoplastic elastomer 1 is 35 mass% or more. The weight-average molecular weight of thermoplastic elastomer 1 refers to the weight-average molecular weight of the entire thermoplastic elastomer 1. The styrene content of thermoplastic elastomer 1 refers to the styrene content of the entire thermoplastic elastomer 1.

[0025] Weight-average molecular weight of thermoplastic elastomer 1 The upper limit of the weight-average molecular weight of thermoplastic elastomer 1 can be set to 600,000 or less. From the viewpoint of obtaining better effects of the present invention, the weight-average molecular weight of thermoplastic elastomer 1 is preferably 330,000 or more, and more preferably 330,000 to 500,000. When thermoplastic elastomer 1 contains only styrene-based thermoplastic elastomer 1-a, the weight-average molecular weight of thermoplastic elastomer 1 is the weight-average molecular weight of thermoplastic elastomer 1. When thermoplastic elastomer 1 contains styrene-based thermoplastic elastomer 1-a and styrene-based thermoplastic elastomer 1-b, the weight-average molecular weight of thermoplastic elastomer 1 can be measured by the same method as described above in "(Method for measuring the weight-average molecular weight of styrene-based thermoplastic elastomer 1-a)". In addition, when the thermoplastic elastomer 1 contains a styrene-based thermoplastic elastomer 1-a and a styrene-based thermoplastic elastomer 1-b, the weight average molecular weight of the thermoplastic elastomer 1 is the weight average molecular weight of each styrene-based thermoplastic elastomer. Alternatively, the weight average molecular weight may be calculated as the sum of values ​​obtained by multiplying the molecular weight by the mass fraction of each styrene-based thermoplastic elastomer (weighted average molecular weight). When thermoplastic elastomer 1 contains styrene-based thermoplastic elastomer 1-a and styrene-based thermoplastic elastomer 1-b, the weight average molecular weight of thermoplastic elastomer 1 is preferably 330,000 or more, more preferably 330,000 to 500,000, and even more preferably 330,000 to 370,000, from the viewpoint of achieving better effects of the present invention.

[0026] Styrene content of thermoplastic elastomer 1 The upper limit of the styrene content of thermoplastic elastomer 1 can be set to 50% by mass or less. From the viewpoint of obtaining superior effects of the present invention, the styrene content of thermoplastic elastomer 1 is preferably 35 to 45% by mass. When thermoplastic elastomer 1 contains only styrene-based thermoplastic elastomer 1-a, the styrene content of thermoplastic elastomer 1 is the same as the styrene content of styrene-based thermoplastic elastomer 1-a. When thermoplastic elastomer 1 contains only styrene-based thermoplastic elastomer 1-a, the styrene content of thermoplastic elastomer 1 is preferably 38% by mass or more, and more preferably 40 to 45% by mass, from the viewpoint of achieving better effects of the present invention. When thermoplastic elastomer 1 contains styrene-based thermoplastic elastomer 1-a and styrene-based thermoplastic elastomer 1-b, the styrene content of thermoplastic elastomer 1 can be measured by the same method as described above in "(Method for measuring the styrene content of styrene-based thermoplastic elastomer 1-a)". Furthermore, when thermoplastic elastomer 1 contains styrene-based thermoplastic elastomer 1-a and styrene-based thermoplastic elastomer 1-b, the styrene content of thermoplastic elastomer 1 may be calculated as the sum of the values ​​obtained by multiplying the styrene content of each styrene-based thermoplastic elastomer by the mass fraction of each styrene-based thermoplastic elastomer (weighted average styrene content). When the thermoplastic elastomer 1 contains a styrene-based thermoplastic elastomer 1-a and a styrene-based thermoplastic elastomer 1-b, the styrene content of the thermoplastic elastomer 1 is preferably 35% by mass or more, from the viewpoint of achieving better effects of the present invention.

[0027] (Thermoplastic elastomer 1 content ratio) From the viewpoint of achieving superior effects of the present invention, the content ratio of thermoplastic elastomer 1 is preferably 5 to 50 mass % and more preferably 10 to 30 mass % of the total amount of the composition of the present invention.

[0028] [Aliphatic Tackifying Resin] The composition of the present invention contains an aliphatic tackifying resin. In the present invention, the aliphatic tackifying resin refers to an aliphatic hydrocarbon resin having tackiness.

[0029] The structure of the aliphatic tackifying resin may be linear, branched, cyclic, or a combination thereof. Examples of the aliphatic tackifying resin include unhydrogenated alicyclic tackifying resins such as dicyclopentadiene resins, C5 hydrocarbon resins, C5 / C9 hydrocarbon resins, and C9 hydrocarbon resins; and hydrogenated alicyclic tackifying resins such as hydrogenated dicyclopentadiene resins, hydrogenated C5 hydrocarbon resins, hydrogenated C5 / C9 hydrocarbon resins, and hydrogenated C9 hydrocarbon resins. (Hydrogenated Alicyclic Tackifying Resin) From the viewpoint of achieving superior effects of the present invention, the aliphatic tackifying resin preferably contains an alicyclic tackifying resin (including a hydrogenated product), more preferably a hydrogenated alicyclic tackifying resin, and even more preferably a hydrogenated dicyclopentadiene resin. In one preferred embodiment, the aliphatic tackifying resin does not have an aromatic hydrocarbon group.

[0030] (Weight-average molecular weight of aliphatic tackifier resin) The weight-average molecular weight of the aliphatic tackifier resin is such that the effect of the present invention is more excellent. From this viewpoint, the weight average molecular weight is preferably 300 to 2,000, and more preferably 400 to 1,500. The weight average molecular weight of the aliphatic tackifying resin can be expressed as a standard polystyrene equivalent value based on measurements obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0031] (Aliphatic tackifying resin content) From the viewpoint of achieving better effects of the present invention, the content of the aliphatic tackifying resin is preferably 150-350 parts by mass, and more preferably 200-300 parts by mass, per 1:100 parts by mass of the thermoplastic elastomer.

[0032] [Paraffin Oil] The composition of the present invention contains paraffin oil. Examples of paraffin oil include paraffin oil obtained by hydrogenating petroleum fractions or residual oils. Examples of suitable paraffin oils include lubricating base oils obtained by purification or cracking. In one preferred embodiment, the paraffin oil contains a compound represented by the formula CnH2n + 2. In the present invention, the value of n can be determined according to the weight-average molecular weight of the paraffin oil. The weight-average molecular weight of paraffin oil will be described later. In one preferred embodiment, the paraffin oil is liquid at room temperature (23°C). In the present invention, the paraffin oil does not contain the aliphatic tackifying resin.

[0033] (Weight-average molecular weight of paraffin oil) The paraffin oil contained in the composition of the present invention has a weight-average molecular weight of It is preferable that the composition contains a paraffin oil having a weight-average molecular weight of 600-1600. Examples of the paraffin oil contained in the composition of the present invention include high molecular weight paraffin oil having a weight-average molecular weight of 1000-1600 and low molecular weight paraffin oil having a weight-average molecular weight of 600 or more and less than 1000. The paraffin oil contained in the composition of the present invention preferably contains a high molecular weight paraffin oil, from the viewpoint of achieving superior effects of the present invention.

[0034] (Method for measuring weight-average molecular weight of paraffin oil) In the present invention, the weight-average molecular weight of paraffin oil refers to the weight-average molecular weight converted into standard polystyrene based on the measurement value by gel permeation chromatography (GPC) (the same applies hereinafter). The measurement conditions for the weight-average molecular weight of the above-mentioned paraffin oil are as follows:

[0035] (Conditions for measuring the weight-average molecular weight of paraffin oil) GPC: LCS solution (Shimazu) Detector: SPD-20A (Shimazu) Column: Two MIXEDE (Polymer Laboratories) in series Solvent: Tetrahydrofuran Temperature: 40°C 0 Flow rate: 0.5 m / min Concentration: 2 mg / ml Standard sample: polystyrene

[0036] (Paraffin Oil Content) From the viewpoint of achieving superior effects of the present invention, the content of paraffin oil is preferably 300 to 600 parts by mass, and more preferably 400 to 500 parts by mass, per 1:100 parts by mass of thermoplastic elastomer. When the paraffin oil contains two or more types of paraffin oil (for example, when the paraffin oil contains a high molecular weight paraffin oil and a low molecular weight paraffin oil), the total content of the two or more types of paraffin oil per 1:100 parts by mass of thermoplastic elastomer can be set to the same range as the above-mentioned paraffin oil content.

[0037] (High molecular weight paraffin oil content) When paraffin oil contains high molecular weight paraffin oil, From the viewpoint of achieving a superior effect of the present invention, the content of fin oil is preferably 300 to 600 parts by mass, more preferably 400 to 500 parts by mass, per 1:100 parts by mass of thermoplastic elastomer.

[0038] (Low molecular weight paraffin oil content) From the viewpoint of achieving better effects of the present invention, the content of low molecular weight paraffin oil is preferably 0 to 100 parts by mass per 1:100 parts by mass of thermoplastic elastomer.

[0039] [Antioxidant] The composition of the present invention contains an antioxidant. Examples of antioxidants include hindered phenol-based antioxidants (e.g., Irganox 1010 and Sumilizer GS, both trade names), phosphite-based antioxidants (e.g., Irgafos 168 and Adekastab HP-100, both trade names), amine-based antioxidants (e.g., Irganox L06), and combinations thereof. From the viewpoint of achieving better effects of the present invention, it is preferable that the antioxidant contains a hindered phenol-based antioxidant.

[0040] (Antioxidant Content) From the viewpoint of achieving superior effects of the present invention, the content of the antioxidant is preferably 5 to 30 parts by mass, and more preferably 15 to 25 parts by mass, per 1:100 parts by mass of thermoplastic elastomer.

[0041] (Additives) The composition of the present invention may further contain additives as needed. Examples of additives include fillers, softeners or plasticizers other than paraffin oil, reinforcing agents, and ultraviolet absorbers. The amount of additives can be determined appropriately.

[0042] (Production Method) The composition of the present invention can be produced, for example, by mixing the above-mentioned essential components under conditions of 150-250°C. Furthermore, examples of methods for producing the composition of the present invention include the "Method for producing the hot melt composition of the present invention" described below.

[0043] (Uses) The composition of the present invention can be used, for example, as an adhesive.

[0044] (Method of Use) The composition of the present invention can be used, for example, by applying the composition of the present invention to a patient for 190 to 230 minutes. 0 The composition of the present invention is applied to an adherend (e.g., a first member and / or a second member) by heating to a temperature of C, melting the composition, and bonding or laminating the adherends to form a bonded or laminated body, and the bonded or laminated body is then placed at room temperature to solidify the composition of the present invention. The material of the second member may be the same as or different from that of the first member.

[0045] Substrates (adherends) to which the composition of the present invention can be applied include, for example, plastics [e.g., polyolefins such as polypropylene; polycarbonates; (meth)acrylic resins], wood, rubber, glass, and metals. Preferred embodiments of the composition of the present invention include the use of the composition for bonding polycarbonate resins, (meth)acrylic resins, or polypropylene, or for bonding polycarbonate resins or (meth)acrylic resins to polypropylene.

[0046] The composition of the present invention can be used, for example, as a hot melt composition for lamps. Examples of lamps include automobile lamps (e.g., headlamps, rear combination lamps, etc.) and two-wheeled (motorcycle) lamps. One of the preferred embodiments of the composition of the present invention is to use it for automobile lamps. When the composition of the present invention is used for automobile lamps, for example, the composition of the present invention can be used for sealing (adhesion) between the lens and housing of the automobile lamp, or for the sealing portion of the lens. Examples of materials for the lens or housing of an automobile lamp include polycarbonate. Polyester resin, (meth)acrylic resin, and polypropylene are used. [0047I] The composition of the present invention can be applied to a substrate (adherend) using, for example, a dispenser (applicator).

[0048] [Method for producing hot melt composition of the present invention] The method for producing a hot melt composition of the present invention (the production method of the present invention) comprises mixing thermoplastic elastomer 1, an aliphatic tackifying resin, paraffin oil, and an antioxidant to produce a hot melt composition in which the weight-average molecular weight of the thermoplastic elastomer 1 is 300,000 or more and the styrene content of the thermoplastic elastomer 1 is 35 to 45 mass%.

[0049] According to the production method of the present invention, it is possible to produce a hot melt composition that is easy to work with, has a low compression set of the cured product obtained, and is easy to recover.

[0050] The hot melt composition produced by the production method of the present invention contains a thermoplastic elastomer 1, an aliphatic tackifying resin, paraffin oil, and an antioxidant, and it is sufficient that the weight-average molecular weight of the thermoplastic elastomer 1 is 300,000 or more and the styrene content of the thermoplastic elastomer 1 is 35 to 45 mass%.

[0051] In the production method of the present invention, the weight-average molecular weight of the thermoplastic elastomer 1 being 300,000 or more may mean that the weight-average molecular weight of the thermoplastic elastomer 1 used in the production method of the present invention or the weight-average molecular weight of the thermoplastic elastomer 1 contained in the hot-melt composition produced by the production method of the present invention is 300,000 or more. In the production method of the present invention, the styrene content of the thermoplastic elastomer 1 being 35 to 45% by mass may mean that the styrene content of the thermoplastic elastomer 1 used in the production method of the present invention or the styrene content of the thermoplastic elastomer 1 contained in the hot-melt composition produced by the production method of the present invention is 35 to 45% by mass.

[0052] The thermoplastic elastomer 1 in the production method of the present invention is This corresponds to the case where the weight average molecular weight of thermoplastic elastomer 1 in the manufacturing method of the present invention is 300,000 or more and the styrene content is 35 to 45 mass%. The aliphatic tackifying resin in the manufacturing method of the present invention corresponds to the aliphatic tackifying resin in the composition of the present invention, and preferred embodiments of the aliphatic tackifying resin in the manufacturing method of the present invention are also the same as those in the composition of the present invention. The paraffin oil and antioxidant in the manufacturing method of the present invention are also the same as those in the composition of the present invention.

[0053] (Method for measuring weight-average molecular weight of thermoplastic elastomer 1) The weight-average molecular weight of thermoplastic elastomer 1 in the production method of the present invention can be measured or calculated by the same method as described above in "(Method for measuring weight-average molecular weight of styrene-based thermoplastic elastomer 1-a)".

[0054] (Method for measuring styrene content of thermoplastic elastomer 1) The styrene content of thermoplastic elastomer 1 in the production method of the present invention can be measured or calculated by the same method as described above in "(Method for measuring styrene content of styrene-based thermoplastic elastomer 1-a)". When thermoplastic elastomer 1 contains only styrene-based thermoplastic elastomer 1-a, the styrene content of styrene-based thermoplastic elastomer 1-a is the styrene content of thermoplastic elastomer 1. When thermoplastic elastomer 1 contains styrene-based thermoplastic elastomer 1-a and styrene-based thermoplastic elastomer 1-b, the styrene content of thermoplastic elastomer 1 can be measured or calculated by the same method as described above in "(Method for measuring styrene content of styrene-based thermoplastic elastomer 1-a)".

[0055] (SEEPS having a weight-average molecular weight of 300,000 or more and a styrene content of 35% by mass or more) From the viewpoint of achieving better effects of the present invention, it is preferable to use a SEEPS having a weight-average molecular weight of 300,000 or more and a styrene content of 35% by mass or more as the thermoplastic elastomer 1 in the production method of the present invention. The sEEPS that can be used in the production method of the present invention corresponds to the SEEPS (the above-mentioned styrene-based thermoplastic elastomer 1-a) in the composition of the present invention, which has a weight-average molecular weight of 300,000 or more and a styrene content of 35 mass% or more, and the preferred embodiments of the styrene-based thermoplastic elastomer 1-a that can be used in the production method of the present invention are also the same as those of the composition of the present invention.

[0056] (Styrenic thermoplastic elastomer 1-b) From the viewpoint of achieving better effects of the present invention, it is preferable to use, in addition to styrene thermoplastic elastomer 1-a, as the thermoplastic elastomer 1 in the production method of the present invention, styrene thermoplastic elastomer 1-b having a weight average molecular weight of 200,000 or more and a styrene content of 30% by mass or less. The styrene thermoplastic elastomer-1-b that can be used in the production method of the present invention corresponds to the styrene thermoplastic elastomer 1-b in the composition of the present invention, and the preferred embodiments of the styrene thermoplastic elastomer 1-b that can be used in the production method of the present invention are also the same as those of the composition of the present invention.

[0057] (Additives) In the production method of the present invention, additives can be added to the essential components as needed. Examples of additives include fillers, softeners or plasticizers other than paraffin oil, reinforcing agents, and ultraviolet absorbers. The amount of additives can be determined appropriately.

[0058] [Mixing] In the production method of the present invention, the mixing method for mixing the thermoplastic elastomer 1 and the like is not particularly limited. For example, mixing can be performed using a Banbury mixer, a pressure kneader, a Henschel mixer, or a Brabender kneader. In the production method of the present invention, the mixing temperature for mixing the thermoplastic elastomer 1 and the like can be, for example, 150 to 250°C. Example The present invention will be described in more detail below with reference to the following examples. The materials, amounts used, proportions, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[0060] [Manufacturing of hot melt composition] Each component shown in Table 1 is used in the amount (parts by mass) shown in the same table, and these are mixed together in a 200 0 Each hot melt composition was produced by mixing under the conditions of C. Table 1 shows the weight average molecular weight and styrene content of thermoplastic elastomer 1 (total). In Table 1, when thermoplastic elastomer 1 further contains styrene-based thermoplastic elastomer 1-b, the weight average molecular weight and styrene content of thermoplastic elastomer 1 (total) are calculated values.

[0061] [Evaluation] The hot melt compositions prepared as described above were evaluated as follows, and the results are shown in Table 1.

[0062] [Workability] The viscosity (Pa•s) of each hot melt composition produced as described above was measured using a Brookfield viscometer at 220°C with a spindle No. 29 and a rotation speed of 5 rpm. In the present invention, the workability when applying the hot melt composition to a substrate was evaluated based on the viscosity measurement results, according to the following criteria: When the viscosity of a hot-melt composition at 220°C was 60 Pa·s or less, the workability of the hot-melt composition was evaluated as being very good, and this was indicated by "©J." When the viscosity was more than 60 Pa·s and not more than 10 Pa·s, the workability of the hot-melt composition was evaluated as being good, and this was indicated by "○." On the other hand, when the viscosity was more than 100 Pa·s, the workability of the hot-melt composition was evaluated as being poor, and this was indicated by "X."

[0063] [Compression set] Each molten hot melt composition was cooled to room temperature and processed into a cylindrical sample of 27 mm (diameter) x 20 mm (height). Each sample was compressed by 50% in the height direction and maintained at 80% compression. 0 After 24 hours, the heating was stopped and the compression was released. 0 C atmosphere for 24 hours. 2. 0 The height (mm) of the sample after leaving it in a 20°C atmosphere for 24 hours was measured, and the compression set was calculated according to the following formula: Compression set (%) = (initial height - height after leaving it in a 20°C atmosphere for 24 hours) / 50% Displacement due to compression x 1 00 Initial height: 20mm Displacement due to 50% compression: 10 mm In the present invention, if the compression set calculated as above is 50% or less, the resulting cured product is evaluated as having a low compression set, and this is indicated by "O". A compression set smaller than 50% is preferable. On the other hand, if the compression set exceeds 50%, the resulting cured product is evaluated as having a high compression set, and this is indicated by "X". The number written alongside "O" or "X" is the compression set value (%).

[0064] [Method for measuring maximum strength (tensile strength) and tensile elongation] Each hot melt composition (hot melt material) was pressed into a sheet, which was then processed into a sample measuring 10 mm long x 50 mm wide x 2 mm thick. A tensile test was conducted using each of the above samples at 20°C and a rate of 500 mm / min to measure the maximum strength (MPa) and elongation at break (%). The obtained maximum strength results are shown in the tensile strength column of Table 1. The obtained elongation at break (%) results are shown in the tensile elongation column of Table 1.

[0065] [Recoverability] In the present invention, based on the results of the measurement of the maximum strength (tensile strength), recoverability (recoverability when recovering a cured product of the hot melt composition from a substrate) is evaluated based on the following criteria: The recoverability was evaluated according to the following standard. When the maximum strength (tensile strength) was 0.8 MPa or more, the recoverability was evaluated as being very excellent, and this was marked with "◎". When the maximum strength (tensile strength) was 0.6 MPa or more and less than 0.8 MPa, the recoverability was evaluated as being excellent, and this was marked with "◯". On the other hand, when the maximum strength (tensile strength) was less than 0.6 MPa, the recoverability was evaluated as being poor, and this was marked with "X". The numbers listed with "◎", "◯", and "X" are the maximum strength (tensile strength) values ​​(MP a).

[0066] (Evaluation Criteria for Tensile Elongation) In the present invention, when the tensile elongation was 1700% or more, the tensile elongation was evaluated as being very excellent, and this was marked with "◎". When the tensile elongation was 1500% or more but less than 1700%, the tensile elongation was evaluated as being excellent, and this was marked with "◯". When the tensile elongation was 1500% or more, this was preferred from the viewpoint that the cured product of the hot melt composition could easily follow the deformation of the substrates. The tensile elongation greater than 1500% was more preferred. On the other hand, when the tensile elongation was less than 1500%, the tensile elongation was evaluated as being poor, and this was marked with "X". The numbers listed with "◎", "◯", and "X" indicate the tensile elongation value (%).

[0067] Country [ Flying hit [Table 3] [0070I Details of each component shown in Table 1 are as follows: [Styrene-based thermoplastic elastomer] The styrene content of each styrene-based thermoplastic elastomer shown below is expressed as "StJ", its unit (mass%) is expressed as "%", and the weight average molecular weight is expressed as "Mwj". Styrene-based thermoplastic elastomer 1—a—1: SEE PS (S t 40%, Mw 350,000), product name SEPTON J 3341 s Manufactured by Kuraray.

[0071] Styrene-based thermoplastic elastomer 1 — b — 1: SEE PS (S t 30%, Mw 300,000), product name Septon 4055, manufactured by Kuraray Co., Ltd. Styrene-based thermoplastic elastomer 1-b-2: SE BS (S t 33%, M w2 70,000), product name Kraton G 1651s Kraton Styrene-based thermoplastic elastomer 1-b-3: SEE PS (S t 30%, Mw 390,000), product name: SEPTON 4077 S Made by Kuraray Styrene-based thermoplastic elastomer 1 — b — 4: SEE PS (S t 30%, Mw480,000), product name Septon 4099, manufactured by Kuraray Co., Ltd. Comparative elastomer 1: SE PS (S t 65%, Mw 90,000), product name Cepton 2104, manufactured by Kuraray Co., Ltd. Comparative elastomer 2: SE BS (S t 58%, Mw2 60,000), trade name Krayton A 1535 S Kraton

[0072] [Tackifying resin] Aliphatic tackifying resin 1: Hydrogenated dicyclopentadiene petroleum resin. Product name T-REZ HA 1 25, manufactured by Mitsui Chemicals. Weight average molecular weight 57〇 •Aliphatic tackifying resin 2: Fully hydrogenated alicyclic hydrocarbon resin. Product name: Alcon P 1 25, manufactured by Arakawa Chemical Co., Ltd. Weight average molecular weight 1 260〇 •Aromatic tackifier resin (comparison): Product name FMRO 1 50, manufactured by Mitsui Chemicals.

[0073] [Paraffin oil] High molecular weight paraffin oil: Product name PW-380, manufactured by Idemitsu Kosan Co., Ltd. Weight average molecular weight 1,500 Low molecular weight paraffin oil: Product name PW-90, manufactured by Idemitsu Kosan Co., Ltd. Weight average molecular weight 900

[0074] [Antioxidants] •Antioxidant: Hindered phenolic antioxidant. Product name: Irganox 1 01 0, manufactured by B AS F.

[0075] The results in Table 1 confirm that the hot melt composition of the present invention exhibits the desired effects. Furthermore, it was confirmed that the hot melt composition having the desired effects can be produced by the method for producing a hot melt composition of the present invention. On the other hand, the hot-melt compositions of Comparative Examples 1, 4, and 5, which did not contain the specified thermoplastic elastomer 1-a, were unsatisfactory in any of workability, compression set, and recoverability. The hot-melt composition of Comparative Example 2, which did not contain an aliphatic tackifying resin but instead contained an aromatic tackifying resin, had poor workability and a high compression set. The hot-melt composition of Comparative Example 3, which did not contain an antioxidant, had a high compression set and poor recoverability.

[0077] Furthermore, the hot-melt compositions of Comparative Examples 1 and 5, which were produced by a production method in which the styrene content of the thermoplastic elastomer 1 did not fall within the specified range, at least had poor recoverability. The hot-melt composition of Comparative Example 2, which was produced by a production method in which an aromatic tackifying resin was used instead of an aliphatic tackifying resin, had poor workability and a high compression set. The hot-melt composition of Comparative Example 3, which was produced by a production method in which no antioxidant was used, and the hot-melt composition of Comparative Example 4, which was produced by a production method in which the weight-average molecular weight of the thermoplastic elastomer 1 did not fall within the specified range, had high compression set and poor recoverability.

Claims

27 Scope of Claim

1. A hot melt composition comprising: a thermoplastic elastomer 1 containing SEEPS having a weight average molecular weight of 300,000 or more and a styrene content of 35% by mass or more; an aliphatic tackifying resin; paraffin oil; and an antioxidant.

2. The hot melt composition according to claim 1, wherein the thermoplastic elastomer 1 further contains a styrene-based thermoplastic elastomer 1-b having a weight-average molecular weight of 200,000 or more and a styrene content of 30 mass% or less.

3. The weight average molecular weight of the thermoplastic elastomer 1 is 300,000 or more. The hot melt composition according to claim 1, wherein the thermoplastic elastomer 1 has a styrene content of 35% by mass or more.

4. The hot melt composition according to claim 1, wherein the aliphatic tackifying resin comprises a hydrogenated alicyclic tackifying resin.

5. The hot melt composition according to any one of claims 1 to 4, which is used for an automobile lamp.

6. A method for producing a hot melt composition, comprising mixing a thermoplastic elastomer 1, an aliphatic tackifying resin, paraffin oil, and an antioxidant to produce a hot melt composition, wherein the thermoplastic elastomer 1 has a weight average molecular weight of 300,000 or more and a styrene content of 35 to 45 mass%.

7. The method for producing a hot melt composition according to claim 6, wherein the thermoplastic elastomer 1 is SEEPS having a weight average molecular weight of 300,000 or more and a styrene content of 35 mass% or more.

8. The method for producing a hot melt composition according to claim 7, wherein the thermoplastic elastomer 1 further comprises a styrene-based thermoplastic elastomer 1-b having a weight average molecular weight of 200,000 or more and a styrene content of 30 mass% or less.

9. The method for producing a hot melt composition according to claim 6, wherein a hydrogenated alicyclic tackifying resin is used as the aliphatic tackifying resin.

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