Photocurable hot-melt composition

Abstract

To provide a photocurable hot-melt composition which has high workability due to its moderate melt viscosity, exhibits good initial adhesion when bonding an adherend, and has improved adhesive strength because of its high peel strength.SOLUTION: The photocurable hot-melt composition contains a photocurable styrenic thermoplastic elastomer (A), a tackifier (B), a softener (C), and a photopolymerization initiator (D). The photocurable hot-melt composition contains, as the softener (C), an oil (c1) containing 35% or more of a naphthenic component.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In general, hot melt compositions are solvent-free, environmentally friendly, can be cured in a short time, and are very easy to handle, which makes it possible to improve the working environment at manufacturing sites. Therefore, hot melt compositions are widely used in precision fields such as automobiles and electrical appliances, as well as in the construction field.

[0003] In the past, the applicant invented a hot melt composition containing hydrogenated paraffin process oil, high molecular weight styrene block copolymer, polyphenylene ether resin or modified polyphenylene ether resin, tackifier resin, and antioxidant as essential components (Patent Document 1). This hot melt composition maintained high viscosity retention and tensile strength retention even after being exposed to high temperatures, and also had excellent dismantling properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-189844 A

[0005] Traditionally, various adhesives have been used in the automotive and electrical equipment fields to fasten components together, but the use of hot melt compositions is on the rise because they are extremely easy to handle, do not require a drying process, and have excellent adhesive stability at room temperature of around 23°C.

[0006] In particular, when hot melt compositions are used for automobile interior materials or optical components, improvements in the initial adhesion when the adherends are attached and the adhesive strength after solidification are required, and there is room for improvement. Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a photocurable hot melt composition which has a moderate melt viscosity and therefore high workability, exhibits good initial adhesion when attached to an adherend, and has a high peel strength and therefore improved adhesive strength. [Means for solving the problem]

[0008] The present invention relates to a photocurable hot melt composition comprising a photocurable styrene-based thermoplastic elastomer (A), a tackifier (B), a softener (C), and a photopolymerization initiator (D), wherein the softener (C) is an oil (c1) containing 35% or more of a naphthenic component. Effect of the Invention

[0009] The photocurable hot melt composition of the present invention has the following advantages: it has a moderate melt viscosity, which makes it easy to work with; it has good initial adhesion when attached to an adherend; and it has high peel strength, which improves adhesive strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Photocurable styrene-based thermoplastic elastomer> In the present invention, a photocurable styrene-based thermoplastic elastomer (A) is used as a base polymer for the hot melt composition of the present invention.

[0011] Styrenic thermoplastic elastomers are mainly composed of hard blocks derived from styrene compounds and soft blocks derived from diene compounds. The bonding form of each block can be linear, branched, or radial, but linear ones are relatively common.

[0012] Specific examples of styrene-based thermoplastic elastomers include styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), 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, a photocurable styrene-based thermoplastic elastomer (A) is particularly used. Photocurable refers to a type that has crosslinking sites in its chemical structure and undergoes crosslinking and hardening when irradiated with light such as ultraviolet (UV) or electron beam (EB). The bonding form of the component (A) may be linear, branched, or radial, but is particularly preferably linear.

[0014] Generally, hot melt compositions melt at a high temperature of about 150° C. and solidify when cooled to room temperature, and therefore can be suitably used as adhesives. In particular, the photocurable hot melt composition of the present invention is characterized by being able to bond more firmly because it not only solidifies when cooled but also hardens when photocured.

[0015] Specific examples of the component (A) include Kraton DX0222 (trade name, manufactured by Kraton Corporation, photocurable, styrene-butadiene-styrene block copolymer (SBS)).

[0016] In addition to the component (A), a non-photocurable styrene-based thermoplastic elastomer can be used within the scope of the present invention, such as TAIPOL 3206 (product name, manufactured by TSRC, styrene-butadiene-styrene block copolymer (SBS)), VECTOR 4293A (product name, manufactured by TSRC, styrene-isoprene-styrene block copolymer (SIS)), and SEPTON 4055 (product name, manufactured by Kuraray, styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS)).

[0017] <Tackifier> In the present invention, a tackifier (B) is used. Examples of the type of component (B) include terpene resins, terpene phenol resins, rosin resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, alicyclic hydrocarbon resins, and hydrogenated or modified products thereof.

[0018] The softening point of the component (B) is preferably from 60 to 250°C, more preferably from 70 to 200°C, and particularly preferably from 80 to 180°C.

[0019] The blending ratio of the (B) component is preferably 1 to 1000 parts by weight, more preferably 15 to 800 parts by weight, and particularly preferably 30 to 600 parts by weight, per 100 parts by weight of the (A) component.

[0020] Specific examples of the component (B) include YS Resin PX1250 (trade name, manufactured by Yasuhara Chemical Co., Ltd., terpene resin, softening point: 120°C to 130°C), Tamanor 803L (trade name, manufactured by Arakawa Chemical Industries, Ltd., terpene phenol resin, softening point: 145°C to 160°C), Pine Crystal KR-85 (trade name, manufactured by Arakawa Chemical Industries, Ltd., rosin resin, softening point: 80°C to 87°C), HM-1000 (trade name, manufactured by Henghe Co., Ltd., aromatic hydrocarbon resin, softening point: 100°C), and T-REZ HA125 (trade name, manufactured by ENEOS Corporation, hydrogenated alicyclic hydrocarbon resin, softening point: 120°C to 130°C).

[0021] <Softener> In the present invention, a softener (C) is used. The (C) component may be, for example, an organic compound that is liquid at room temperature (about 23° C.). The (C) component improves the dispersibility of the (A) and (B) components, thereby increasing the wettability of the adherend surface and improving the adhesion between the layers.

[0022] In the present invention, in particular, oil (c1) containing 35% or more naphthenic components is used as the component (C). The component (c1) is obtained by distilling naphthenic crude oil mainly under normal or reduced pressure, followed by extraction and refining, and is generally characterized by high fluidity and low viscosity. The component (c1) preferably contains 35% or more naphthenic components, more preferably 40% or more, and particularly preferably 45% or more.

[0023] The inventors of the present invention found that the use of component (c1) improves the initial adhesion when the adherend is laminated and the adhesive strength after solidification, and thus completed the present invention. One of the factors that produces such an effect is presumably that naphthenic components are more compatible with the hard and soft blocks of component (A) than paraffinic components and the like.

[0024] In addition, softeners (c2) other than the above-mentioned (c1) component can be used within the scope that does not impair the effects of the present invention. Examples of the (c2) component include polybutene, polyisobutylene, liquid wax, etc. Among these, polybutene is preferably used because it is highly stable and easy to handle.

[0025] By using the component (c2) in addition to the component (c1), the initial adhesion when the adherend is laminated tends to be further improved. One of the factors that produces such an effect is presumably that the use of the component (c2) suppresses the entanglement of carbon chains in the soft block of the component (A) and increases flexibility.

[0026] The blending ratio of the (C) component is preferably 1 to 800 parts by weight, more preferably 10 to 600 parts by weight, and particularly preferably 20 to 500 parts by weight, per 100 parts by weight of the (A) component.

[0027] Specific examples of the (c1) component include KN-4006 (trade name, manufactured by Karamay Corporation, naphthenic component: 56%) and KN-4010 (trade name, manufactured by Karamay Corporation, naphthenic component: 52%). Specific examples of the (c2) component include PB-950 (trade name, manufactured by Dealim Corporation, polybutene), PB-1300 (trade name, manufactured by Dealim Corporation, polybutene), Nippon Oil Polybutene HV-50 (trade name, manufactured by ENEOS Corporation, polybutene), and NOF Polybutene 10N (trade name, manufactured by NOF Corporation, polybutene).

[0028] <Photopolymerization initiator> In the present invention, a photopolymerization initiator (D) is used. Specific examples of the (D) component include, but are not limited to, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one.

[0029] The blending ratio of the (D) component is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 30 parts by weight, and particularly preferably 1 to 20 parts by weight, per 100 parts by weight of the (A) component. By blending within this range, the photocurable hot melt composition according to the present invention can be cured efficiently, which tends to improve productivity.

[0030] Specific examples of the component (D) include Omnirad 127, Omnirad 184, Omnirad 369, Omnirad 500, Omnirad 754, Omnirad 819, Omnirad 907, Omnirad 1173, Omnirad 2959, Omnirad BDK(651), Omnirad TPO, Omnirad MBF (product name, all manufactured by IGM RESINS), Irgacure OXE01, Irgacure OXE02, Irgacure OXE04 (product name, all manufactured by BASF Japan), DAIDO UV-CURE PMB, DAIDO UV-CURE OMB, DAIDO UV-CURE BMS, DAIDO UV-CURE 171, DAIDO UV-CURE D-177F, DAIDO UV-CURE #174, PHOTOCURE 550 (product names, all manufactured by Daido Chemical Industry Co., Ltd.), etc.

[0031] Other ethylene-based polymers can be used within the scope of the present invention, so long as the effects of the present invention are not impaired. Examples of ethylene-based polymers that can be used include polyethylene, which is a homopolymer, copolymers of ethylene and a monomer selected from propylene, 1-butene, and 1-hexene, and copolymers of ethylene and unsaturated esters. Examples of unsaturated esters include vinyl acetate and acrylic esters such as methyl acrylate and ethyl acrylate.

[0032] Ethylene-based polymers are generally used as packaging films for hot melt compositions. This is very economical because when applying a hot melt composition in a large-scale facility, the hot melt composition can be put into a large tank together with the packaging film, and the trouble of removing the packaging film can be eliminated. In particular, in the present invention, the use of this component tends to further improve the initial adhesion when the adherend is bonded and the adhesive strength after solidification, so it can be used preferably.

[0033] In the present invention, an antioxidant can be used as an additive. Examples of the type of the component include phosphites, naphthylamines, p-phenylenediamines, quinolines, hydroquinones, bis-tris-polyphenols, thiobisphenols, and hindered phenols, and one or more of them can be used in combination. Specific examples of the component include Sumilizer GP (trade name, manufactured by Sumitomo Chemical Co., Ltd.) and Songnox 1010 (trade name, manufactured by Songwon Co., Ltd.).

[0034] In addition, in the present invention, various additives such as fillers such as calcium carbonate, talc, and clay, preservatives, and colorants may be contained.

[0035] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these descriptions. EXAMPLES

[0036] <Examples and Comparative Examples> The hot melt compositions of the Examples and Comparative Examples were produced by thoroughly kneading the ingredients in the formulation shown in Table 1 in a flask adjusted to 160° C. Here, the numerical values ​​in Table 1 represent parts by weight. The raw materials used are shown below. Kraton DX0222 (product name, Kraton, photocurable, styrene-butadiene-styrene block copolymer (SBS)) HM-1000 (Product name, manufactured by Henghe, aromatic hydrocarbon resin, softening point: 100℃) KN-4010 (product name, manufactured by Karamay, naphthenic components: 52%) Diana Process Oil PW-90 (product name, manufactured by Idemitsu Kosan Co., Ltd., naphthenic components: 28%) PB-950 (product name, Dealim, polybutene) Omnirad BDK(651) (product name, manufactured by IGM RESINS, photopolymerization initiator) EVATHENE UE612 (product name, manufactured by USI, ethylene-vinyl acetate copolymer) Songnox 1010 (product name, manufactured by Songwon, antioxidant)

[0037] [Table 1]

[0038] The hot melt compositions prepared in the above examples were evaluated for various physical properties in the following manner. The results are shown in Table 2.

[0039] <Melt viscosity> The hot melt composition was melted, and the melt viscosity (mPa·s) was measured after 10 minutes using a Brookfield viscometer at a measurement temperature of 160°C, spindle No. 27, and rotation speed of 5 rpm.

[0040] <Preparation of test specimen> The hot melt compositions prepared in the above examples were diluted with a solvent (toluene) and applied to a PET film, which was then left to stand for 3 minutes in a thermostatic oven at 110° C. to dry the solvent, producing a PET film with a thickness of 50 μm on which the hot melt composition was laminated. This laminate was cut into a size of 25 mm×300 mm to prepare a test piece.

[0041] <Initial adhesion (loop tack test)> The above test pieces were aged for 24 hours in a dark place at a temperature of 23°C and humidity of 50%. Then, they were irradiated with an electrode high-pressure mercury lamp (product name: iGrandage ECS4011GX / N, manufactured by iGraphics Co., Ltd.) with an irradiation intensity of 100 mW / cm 2 , Accumulated light output: 2,970mJ / cm 2 After irradiating with ultraviolet light at 100° C., the ends of the test pieces were overlapped to form an ellipse with the hot melt composition applied to the outside, and the test piece was attached to the upper side of a tensile tester, and a stainless steel plate was attached to the lower side of the tensile tester horizontally to the floor. The test piece was then lowered at 300 mm / min so that it was in contact with the stainless steel plate, and after 15 seconds, it was raised at the same speed, and the maximum value of the tensile strength was taken as the initial adhesion (N / 25 mm).

[0042] <Peel strength (180 degree peel test)> The surface of the test piece coated with the hot melt composition was attached to a SUS plate (attached area: 25 mm × 80 mm), pressed twice with a 2 kg roll, and then aged for 24 hours in a dark place at a temperature of 23°C and a humidity of 50%. Then, an electrode high-pressure mercury lamp (product name: iGrandage ECS4011GX / N, manufactured by iGraphics Co., Ltd.) was used to irradiate the test piece with an intensity of 100 mW / cm. 2 , Accumulated light output: 2,970mJ / cm 2 After irradiating with ultraviolet light at 400 rpm, the end of the PET film and the end of the SUS plate were attached to a Technograph testing machine (manufactured by Minebea), and the average strength when peeled in a 180 degree direction at 300 mm / min was recorded as the peel strength (N / 25 mm).

[0043] [Table 2]

[0044] When the hot melt compositions according to the Examples and Comparative Examples were produced, the melt viscosities at 160°C were comparable, but the Examples showed better initial adhesion when attached to the adherend than the Comparative Examples, and the peel strength was higher, indicating that the adhesive strength was improved. In addition, the initial adhesion tended to be improved by using a softener (c2) other than the oil (c1) containing 35% or more naphthenic components. And the initial adhesion and adhesive strength tended to be further improved by using an ethylene-unsaturated ester copolymer.

Claims

1. The composition contains a photocurable styrene-based thermoplastic elastomer (A), a tackifier (B), a softener (C), and a photopolymerization initiator (D), 1. A photocurable hot melt composition comprising, as a softener (C), an oil (c1) containing 35% or more of a naphthenic component.

2. 2. The photocurable hot melt composition according to claim 1, further comprising a softener (c2) other than the oil (c1) containing 35% or more of naphthenic components.

3. 3. The photocurable hot melt composition according to claim 1, further comprising an ethylene polymer.

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