JP2005171164A - Method for bonding olefinic resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for the bonding to an olefinic substrate to give higher adhesiveness-improving effect compared with plasma irradiation and corona discharge treatment. <P>SOLUTION: A substrate made of an olefinic resin is coated with a surface-modifying resin composed of a polymer having an SP value of 7-10 and a photopolymerization initiator, the coating layer is irradiated with light, a thermally fusible layer of a moisture-setting reactive hot-melt adhesive composed mainly of an isocyanate-containing urethane prepolymer and having a melting point of 40-150°C is formed on the coating layer and the substrate composed of the olefinic resin is bonded to an adherend through the coating layer of the surface-modifying resin and the thermally fusible layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for bonding an olefin resin. Specifically, after laminating a surface-modifying resin comprising a polymer having a SP value of 7 to 10 and a photopolymerization initiator on an olefin-based resin and irradiating light, the isocyanate group-containing urethane prepolymer is the main component and the melting point is 40. The present invention relates to a method for adhering an olefin-based resin that is bonded using a moisture-curable reactive hot melt adhesive having a temperature of from 150 ° C. to 150 ° C.

  2. Description of the Related Art In recent years, in the automobile industry and the building materials industry, products that have been manufactured with steel materials, vinyl chloride resins, and the like have been replaced with olefin-based resins with the goal of reducing the weight of components and reducing the environmental burden. Low-activity resins such as polypropylene elastomer and polyethylene elastomer (TPO) with rubber components such as EPDM components added to these resins are inexpensive and have relatively high strength, so bumpers, instrument panels and trims are used for automotive parts. As a building material member, it is widely used as an interior member such as a baseboard and a decorative sheet.

Olefinic resins generally have insufficient adhesion to adhesives, sealants, coatings, etc., so that chlorinated polypropylene is applied to the substrate surface to improve the wettability of the adhesive interface, and then the two-component solvent type And a method using a one-liquid solvent type adhesive.
However, solvent-type adhesives have problems of ignition, explosion risk, deterioration of working environment due to solvents, and utility costs when drying solvents.
In the case of a cyanoacrylate adhesive, there is an adhesion method in which a dedicated surface treatment agent is used in combination, but there is a problem in appearance due to whitening.
Conventionally, surface treatment by corona discharge treatment or plasma discharge has been studied. However, expensive special equipment is required and the effect of improving adhesion is small, and further improved adhesion is lost over time. There is a problem of end.
Another technique for improving adhesion is photo-modification of resin, but has the following problems. According to Japanese Patent Laid-Open No. 64-9243, a method of irradiating ultraviolet rays after contacting an olefin resin with an ultraviolet absorbing solvent has been proposed, but there is a problem in that the contact time is long and the productivity is poor and the modification effect is poor. is there. Japanese Patent Laid-Open No. 5-271444 proposes a method of irradiating an olefin resin with ultraviolet rays, then applying a solution containing a photopolymerization initiator and then irradiating ultraviolet rays again. There are two irradiation processes, the process is complicated, and there is a problem in terms of production cost. Japanese Patent Laid-Open No. 6-336575 proposes a modification method in which a solution containing a photoinitiator is applied to the surface of a substrate and then irradiated with ultraviolet light, and further a primer mainly composed of isocyanate is applied, but the process is complicated. It is not economical.
JP-A 64-009243 JP 05-271444 A Japanese Patent Laid-Open No. 06-336575

    The subject of this invention is providing the adhesion method of the olefin resin which solved the above-mentioned fault and improved the adhesiveness of the base-material surface which consists of olefin resin by a method with high productivity.

  The inventors of the present invention have intensively studied a reforming method for solving the above-mentioned problems and completed the present invention. That is, according to the first aspect of the present invention, a coating layer of a resin for surface modification comprising a polymer having a SP value of 7 to 10 and a photopolymerization initiator is formed on a substrate composed of an olefin resin, After irradiating light onto the coating layer, a heat-melt layer of a moisture curable reactive hot melt adhesive having an isocyanate group-containing urethane prepolymer as a main component and a melting point of 40 ° C. or higher and 150 ° C. or lower is formed on the coating layer. An olefin-based resin bonding method in which a base material made of an olefin-based resin and an adherend are bonded via the surface-modifying resin coating layer and the heat-melting layer. In the invention, the polymer having an SP value of 7 to 10 is a chlorinated polyolefin, and the third invention is a polymer having an SP value of 7 to 10 in the first invention is an acid-modified polyolefin. An adhesive wherein.

A surface modification resin coating layer composed of a polymer having an SP value of 7 to 10 and a photopolymerization initiator is formed on a base material made of an olefin resin, and the moisture curing reaction is performed after irradiating the coating layer with light. By adhering with an adhesive hot melt adhesive, a higher adhesive force can be obtained as compared with the case of no treatment, and a higher adhesive force can be obtained even when compared with plasma irradiation or corona discharge.
In addition, by adopting a solvent-free, moisture-curing reactive hot melt adhesive as an adhesive, compared to conventional solvent-based adhesives, there is an organic solvent ignition, explosion risk, work environment deterioration, solvent Problems such as utility costs during drying can be improved.
By the method of the present invention, substrates made of olefin resin, or olefin resin and various materials such as metal, plastic, ceramics, and glass can be firmly bonded.

Olefin Resin The olefin resin used in the present invention is preferably a polymer of olefins having 2 to 6 carbon atoms, and preferred specific examples include polyethylene, polypropylene (isotactic, syndiotactic, atactic) as rigid polyolefin. The same applies hereinafter), poly-1-butene, poly-4-methyl-1-pentene, and as a polyolefin elastomer, ethylene propylene rubber, EPDM, and TPO (in which ethylene propylene rubber or EPDM is blended with the above hard polyolefin) Thermoplastic polyolefins) and those obtained by adding additives and fillers to the above materials, but are not limited thereto.
The ratio of the olefin component contained in the olefin resin of the present invention is 50% by weight or more, preferably 60% by weight or more.
Examples of other resin components contained in the olefin resin in the present invention include, but are not limited to, a styrene resin, a styrene elastomer, an ethylene methacrylic acid resin, and an ethylene vinyl acetate resin.

○ Polymer having SP value of 7 to 10 The resin component of the resin for surface modification of the present invention preferably has a higher affinity for the olefin resin to be modified, and a polymer having an SP value of 7 to 10 is preferable.
The SP value in the present invention is a solubility parameter, which is a Fedors method [Polym. Eng. Sci. 14 (2) 152, (1974)].
Specific examples are described below, but the present invention is not limited to these.
(1) Rigid polyolefin: Polyethylene, polypropylene (including any of isotactic, syndiotactic, and atactic; the same applies hereinafter), poly-1-butene, poly-4-methyl-1-pentene, and the like.
(2) Polyolefin elastomers: ethylene propylene rubber, EPDM, and polyolefin elastomer (TPO) in which ethylene propylene rubber or EPDM is blended with the above hard polyolefin.
(3) Chlorinated polyolefin: Chlorinated polyethylene, chlorinated polypropylene, chlorinated ethylene-propylene copolymer, chlorinated ethylene-vinyl acetate copolymer, maleic anhydride modified chlorinated polypropylene, acrylic acid modified chlorinated polypropylene, anhydrous Examples include maleic acid-acrylic acid modified chlorinated polypropylene.
(4) Acid-modified polyolefin: In addition to the above-mentioned acid-modified chlorinated polyolefin, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, acrylic acid-modified polypropylene, methacrylic acid-modified polypropylene, maleic anhydride-acrylic acid-modified polypropylene, etc. Can be mentioned.
(5) Other resins: styrene resin, styrene elastomer, ethylene methacrylic acid resin, ethylene vinyl acetate resin and the like.
The proportion of the olefin component contained in the polymer having an SP value of 7 to 10 used in the present invention is preferably 50% by weight or more, more preferably 60% by weight or more.

The chlorine content of the chlorinated polyolefin of the present invention is preferably 1% to 60%, more preferably 1% to 50%.
When the chlorine content is less than 1% or more than 60%, the adhesion of the polyolefin resin to the adhesive is lowered. The reason is presumably that when the chlorine content is low, the wettability of the chlorinated polyolefin to the adhesive decreases, and when the chlorine content is high, the wettability of the chlorinated polyolefin to the polyolefin resin decreases. .

○ Photopolymerization initiator The photopolymerization initiator used in the present invention may be either a hydrogen abstraction type or a photocleavage type. Specifically, benzophenone, parachlorobenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-methoxybenzophenone, methyl 2-benzoylbenzoate, benzophenone sulfide, bis (4-dimethylaminophenyl) ketone, Hydrogen abstraction type compounds such as anthraquinone, 2-ethylanthraquinone, benzyl, acetophenone, p-dimethylaminoacetophenone, pt-butyldichloroacetophenone, thioxanthone, 2,3-diethylthioxanthone, chlorothioxanthone, camphorquinone, 2-hydroxy- 2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-methyl -1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, benzoin alkyl ketal, benzyl methyl ketal, 2,2-diethoxyacetophenone, bis (2,4,6-trimethylbenzoyl) -phenyl Examples of the photocleavable compound include, but are not limited to, phosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

  The amount of photoinitiator added to the surface modifying resin in the present invention is 0.1 to 200 parts by weight, preferably 0.2 to 120 parts by weight, based on 100 parts by weight of the resin. When the amount of photoinitiator is small, sufficient modification effect cannot be obtained even when irradiated with ultraviolet rays, and when the amount is large, no further modification effect can be obtained. The affinity of the resin to the olefin resin is lowered, and the reforming effect is lowered.

Method for preparing surface modifying resin The method for preparing the surface modifying resin of the present invention is described below, but is not limited thereto.
(1) Preparation of solvent-type surface-modified resin composition It can be obtained by dissolving a polymer having an SP value of 7 to 10 and a photopolymerization initiator in an organic solvent such as toluene.
(2) Preparation of Solid Surface Modified Resin Composition A polymer having an SP value of 7 to 10 and a photopolymerization initiator can be obtained by kneading with an extruder, a kneader or the like.

○ Method for forming coating layer of resin for surface modification
(1) Method for Forming Coating Layer of Solvent Type Surface-Modified Resin After applying to olefin resin, it can be laminated by drying. Examples of the application method include, but are not limited to, a method in which a proper amount is impregnated into a brush, a nonwoven fabric, and the like, a roll coat, a spray coat, a dip, and the like. For drying, either natural drying or forced heating drying with hot air can be applied. However, when the outside air temperature is low, both the wettability decreases due to the temperature decrease of the base material and the solution type primer, or the base depends on the type of solvent. A decrease in wettability to the material or a decrease in wettability due to a decrease in the pressing force of application may occur.
If wetting in the solution state is not sufficiently achieved in this way, the surface modifying resin that has failed to wet will be present on the olefin base material, but the surface modifying resin must be heated. Therefore, the wettability between the surface modifying resin and the substrate can be improved.
Therefore, it is preferable to heat dry at a softening point or higher than the melting point of the polymer having an SP value of 7 to 10 or higher and 150 ° C. or lower than natural drying, more preferably 60 ° C. to 180 ° C. It is desirable to obtain a stable adhesiveness that is not subject to When the drying temperature exceeds 180 ° C., the adherend is thermally deformed and deteriorates, which is not preferable. Further, the drying time cannot be limited here because it depends on the shape of the adherend and the characteristics of the dryer.
(2) Solid surface modified resin coating layer forming method Using an extruder, the olefinic resin and the surface modifying resin are extruded in multiple layers to form a coating layer of the surface modifying resin on the surface of the olefinic resin. Form.

Light irradiation Examples of the light irradiation light source used in the present invention include a low-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp, and a metal halide lamp. Moreover, preferable electromagnetic waves for the surface treatment are 180 to 500 nm of ultraviolet rays and visible light. Amount of light irradiation to the surface modifying resin laminated to the olefin resin is usually 100 mJ / cm ² or more, particularly preferably in the 200~10000mJ / cm ^2.
In addition, in order to shorten processing time, the said drying process and the said light irradiation process can also be performed in parallel.

O Moisture curable reactive reactive hot melt adhesive 1) Composition of adhesive The adhesive in the present invention is a moisture curable reactive hot melt adhesive mainly composed of an isocyanate group-containing urethane prepolymer.
The isocyanate group-containing urethane prepolymer is obtained by reacting one or more polyols having two or more hydroxyl groups in the molecule with one or more polyisocyanates having two or more isocyanate groups in the molecule. It is a urethane prepolymer. The preferred weight average molecular weight of the urethane prepolymer is 1000 to 50000. 1 type (s) or 2 or more types can be used as the said urethane prepolymer.

1-2) Polyol The polyol which is a raw material of the urethane prepolymer has 2 or more, preferably 5 or less hydroxyl groups in the molecule, and conventionally known polyols can be used. Preferred specific examples are shown below.

(1) Polyester polyol The polyester polyol is obtained by random copolycondensation of one or more polycarboxylic acids and one or more polyols.
Preferred polycarboxylic acids are those having 2 or more carboxyl groups in the molecule and 4 to 24 carbon atoms. Preferred examples include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, ε-caprolactone, terephthalic acid, isophthalic acid, phthalic anhydride, and 2,6-naphthalenedicarboxylic acid. Acids, trimellitic acid, paraoxybenzoic acid and the like.
A preferred polyol has two or more hydroxyl groups in the molecule and a weight average molecular weight of 60 to 10,000. Preferred specific examples include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1, Examples include 4-cyclohexanedimethanol, trimethylolpropane, pentaerythritol, 1,2,6-hexanetriol.
(2) Polyether polyol The polyether polyol has one or more ether bonds in the molecule, and the preferred polyether polyol has a weight average molecular weight of 200 to 10,000. Preferred examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like.
(3) Polyolefin polyol The polyolefin polyol has a polyolefin skeleton in the molecule, and a preferred polyolefin polyol has a weight average molecular weight of 200 to 10,000. Preferable specific examples include hydrogenated polyalkylene polyols such as hydrogenated polybutadiene polyol and hydrogenated polyisoprene polyol, and α-olefin copolymers.
(4) Other polyols Polyalkylene polyols such as polybutadiene polyol and polyisoprene polyol, and polycarbonate polyols are available.

1-3) Polyisocyanate The polyisocyanate which is a raw material of the urethane prepolymer has two or more isocyanate groups in the molecule, and conventionally known ones can be used.
Specifically, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, 4,4′-diphenylene diisocyanate, 1,5-octylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexa Methylene diisocyanate, pentamethylene diisocyanate, 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, diphenylmethane Diisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane, 1,3-bis (isocyanatemethyl) cyclohexane, Examples include sophorone diisocyanate and carbodiimide-modified 4,4′-diphenylmethane diisocyanate.

  The preferred ratio of the amount of polyisocyanate charged to the polyol when producing the urethane prepolymer in the present invention is 1 to 5 in an equivalent ratio of isocyanate group / hydroxyl group, more preferably 1.2 to 3.

  In addition, in order to increase the moisture reactivity of the adhesive of the present invention, a tertiary amine-based or tin-based catalyst, in addition, a tackifier, a silane coupling agent, a filler, a plasticizer, a wax, a stabilizer, an oxidation An inhibitor or the like can be added as necessary.

2) Adhesive melting point Since the adhesive in the present invention is composed of a urethane prepolymer having a melting point, it becomes a crystalline solid at a temperature below the melting point, so when changing from a molten state to a solid, the viscosity of the resin with the melting point as a boundary. Has a characteristic of rapidly increasing. Therefore, when the adhesive layer applied to the substrate is in a molten state, the adhesive operation is performed, and then the adhesive is crystallized by cooling and solidifying the adhesive, whereby the olefin resin and the other adherend are bonded to each other. It is firmly fixed by the layer, and the initial adhesive strength can be easily obtained.
Specifically, by setting the melting point of the adhesive to 40 ° C. or higher, it is solid in a normal state, and the initial adhesive strength can be obtained by the cohesive force at the time of crystallization. When the melting point is less than 40 ° C., the initial adhesive strength in the normal state cannot be obtained. On the other hand, when the melting point of the adhesive is higher than 150 ° C., harmful substances may be generated when the adhesive is heated and melted, which is not desirable.
The melting point of the adhesive can be measured by observing the presence or absence of melting with a microscope while heating from room temperature at 1 ° C./min.

3) Melt Viscosity of Adhesive The preferable melt viscosity of the adhesive in the present invention is 200 to 100,000 mPa · s in a molten state at 120 ° C., the more preferable melt viscosity is 1000 to 50000 mPa · s, and the more preferable melt viscosity is 1000 to It is 20000 mPa · s, and the most preferred viscosity is 1000 to 10000 mPa · s. The melt viscosity can be easily measured with a BM viscometer.

4) Glass transition temperature of adhesive The preferable glass transition temperature of the adhesive in this invention is -40-60 degreeC, More preferably, it is -30-30 degreeC. By adjusting the glass transition temperature to the above preferred range, an adhesive having excellent adhesion to the substrate can be obtained.

5) Adhesive application method Any method known as a hot melt adhesive application method can be employed. A preferable coating temperature is 80 to 140 ° C, and a more preferable temperature is 80 to 120 ° C.

6) Adhesion method Through the coating layer of the surface modifying resin formed on the surface of the base material made of the olefin resin as described above and the heat melting layer of the moisture curable reactive hot melt adhesive, The base material made of olefin resin and the adherend are joined.
As the adherend, those made of various materials such as olefin resin, metal, plastic, ceramics and glass can be used.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In addition, the performance evaluation in each Example and the comparative example followed the following method.
Preparation of surface modifying resin The composition was prepared according to Table 1.
○ Measurement of tensile shear bond strength The following olefin resin is molded into a width of 25 mm × length of 50 mm × thickness of 2 mm, and a coating layer of a surface modifying resin is formed on the surface of the substrate made of the olefin resin. With respect to the case where the coated surface is irradiated with light and the case where light irradiation is not performed, the adhesive is applied to one side and bonded together, and fixed with a clip (adhesion area width 25 mm × length 12.5 mm). After curing for 3 days under the conditions of 30 ° C. and 65% RH, the tensile shear bond strength was measured according to JIS K 6850.
○ Measurement of peel adhesion strength The following olefin resin is molded into a width of 25 mm x length of 100 mm x thickness of 2 mm, and a coating layer of the surface modifying resin is formed on the surface of the base material made of the olefin resin, and the coating Applying an adhesive to the treated surface, attaching a cotton cloth, pressing with a heavy stone (5N / cm ² ) for 2 minutes, 30 ° C 65% RH After curing for 3 days, the 180 ° peel strength was measured according to JIS K 6854-2.
[Materials used for evaluation]
Olefin resin: Olefin thermoplastic elastomer (trade name Miralastomer C750B manufactured by Mitsui Chemicals, Inc.)
Adhesive: Moisture curable reactive hot melt adhesive mainly composed of isocyanate group-containing urethane prepolymer (trade name Aronmelt R RHT-310, manufactured by Toagosei Co., Ltd.). The melting point is 53 ° C., and the melt viscosity is 3,000 mPa · s in a 120 ° C. molten state.

Light irradiation The light irradiation device used was a high-pressure mercury lamp manufactured by Ushio Electric Co., Ltd. with an output of 3.2 kW, and the irradiation energy was 2000 mJ / cm ² as measured by an integrating photometer with a wavelength of 365 nm.

[Example 1]
The surface modification resin composition 1 is applied to the surface of the olefin resin, dried at room temperature, and then irradiated with light. The adhesive is applied to one side, bonded, and fixed with a clip (adhesion area width) 25mm x length 12.5mm). After curing for 3 days under the conditions of 30 ° C. and 65% RH, the tensile shear bond strength was measured in accordance with JIS K 6850, and the adhesive fracture surface was visually evaluated.
Also, the peel adhesion strength was applied to the surface of the olefin resin by applying the surface-modifying resin composition 1 and dried at room temperature, followed by light irradiation, applying an adhesive to the treated surface, and bonding a cotton cloth. Crushing was performed for 2 minutes with a heavy stone (5 N / cm ² ), curing was performed at 30 ° C. and 65% RH for 3 days, and the peel adhesion strength was measured in accordance with JIS K 6854.

[Example 2]
Adhesion was performed in the same manner as in Example 1 except that the surface modifying resin composition 2 was used, and the tensile shear bond strength between the olefin resins and the peel adhesion strength between the olefin resin and the cotton cloth were measured.

[Example 3]
Except for using the resin composition 3 for surface modification, adhesion was performed in the same manner as in Example 1, and the tensile shear adhesive strength between the olefin resins and the peel adhesive strength between the olefin resin and the cotton fabric were measured.

[Example 4]
Except that the surface-modifying resin composition 4 was used, adhesion was performed in the same manner as in Example 1, and the tensile shear bond strength between olefin resins was measured.

[Example 5]
Adhesion was performed in the same manner as in Example 1 except that the surface modifying resin composition 5 was used, and the tensile shear bond strength between the olefin resins and the peel adhesion strength between the olefin resin and the cotton cloth were measured.

[Example 6]
Adhesion was performed in the same manner as in Example 1 except that the surface modifying resin composition 6 was used, and the tensile shear adhesive strength between the olefin resins and the peel adhesive strength between the olefin resin and the cotton fabric were measured.

[Example 7]
Adhesion was performed in the same manner as in Example 1 except that the surface modifying resin composition 5 was used, and the tensile shear bond strength between the olefin resins and the peel adhesion strength between the olefin resin and the cotton cloth were measured.

[Example 8]
Except for using the resin composition 6 for surface modification, adhesion was performed in the same manner as in Example 1, and the tensile shear bond strength between olefin resins was measured.

[Comparative Example 1]
The surface-modifying resin composition 9 is applied to the surface of the olefin resin and dried at room temperature, and then the adhesive is applied to one side and bonded together and fixed with a clip (adhesion area width 25 mm × length 12). .5mm). After curing for 3 days under the conditions of 30 ° C. and 65% RH, the tensile shear bond strength was measured in accordance with JIS K 6850, and the adhesive fracture surface was visually evaluated.
Also, the peel adhesion strength was obtained by applying the surface-modifying resin composition 9 to the surface of the olefin-based resin, drying at room temperature, applying the adhesive to the treated surface, attaching a cotton cloth, and pressing with a heavy stone for 2 minutes. Clamped (5 N / cm ² ), cured for 3 days under conditions of 30 ° C. and 65% RH, and peel adhesion strength was measured according to JIS K 6854.

[Comparative Example 2]
Adhesion was performed in the same manner as in Comparative Example 1 except that the surface-modifying resin composition 10 was used, and the tensile shear adhesive strength between the olefin resins and the peel adhesive strength between the olefin resin and the cotton fabric were measured.

[Comparative Example 3]
An adhesive is applied to one side of an olefinic thermoplastic elastomer Miralastomer (registered trademark) manufactured by Mitsui Chemicals, and bonded together, and fixed with a clip (adhesion area width 25 mm × length 12.5 mm). After curing for 3 days under the conditions of 30 ° C. and 65% RH, the tensile shear bond strength was measured according to JIS K 6850.

[Comparative Example 4]
Toluene is applied to the surface of Mitsui Chemicals' olefinic thermoplastic elastomer Miralastomer (registered trademark), dried on a heat plate at 80 ° C for 2 minutes, and then the adhesive is applied to one side for bonding. And fix with clips (adhesive area width 25 mm x length 12.5 mm). After curing for 3 days under the conditions of 30 ° C. and 65% RH, the tensile shear bond strength was measured according to JIS K 6850.

[Comparative Example 5]
The surface of the olefinic thermoplastic elastomer Miralastomer (registered trademark) manufactured by Mitsui Chemicals Co., Ltd. is irradiated with plasma using a plasma irradiation device under conditions of an irradiation distance of 6 mm and an irradiation time of 3 seconds, and then an adhesive is applied to one side. Are bonded together and fixed with clips (adhesive area width 25 mm × length 12.5 mm). After curing for 3 days under the conditions of 30 ° C. and 65% RH, the tensile shear bond strength was measured according to JIS K 6850.
As the plasma irradiation apparatus, ST-7000 manufactured by Keyence Corporation was used.

[Comparative Example 6]
The surface of the olefinic thermoplastic elastomer Miralastomer (registered trademark) manufactured by Mitsui Chemicals, Inc. was corona discharged with a corona discharge device under an irradiation distance of 5 mm and an irradiation time of 15 seconds, and then an adhesive was applied to one side. Are bonded together and fixed with clips (adhesive area width 25 mm × length 12.5 mm). After curing for 3 days under the conditions of 30 ° C. and 65% RH, the tensile shear bond strength was measured according to JIS K 6850.
The corona discharge device used was Polydyne manufactured by Navista.

The present invention provides a method for firmly bonding a substrate made of an olefin resin with a solvent-free, moisture-curable reactive hot melt adhesive.
Therefore, the present invention facilitates the replacement of steel products and vinyl chloride resin products with olefin-based resins in the automobile industry and the building materials industry, and promotes weight reduction of members and reduction of environmental burden.
Specifically, automotive parts (bumpers, instrument panels, trims, etc.) and building materials using low activity resins such as polypropylene and polyethylene and polyolefin elastomers (TPO) in which rubber components such as EPDM are added to those resins. Members (baseboards, decorative sheets, etc.) can be manufactured at low cost.

Claims (3)

A coating layer of a resin for surface modification comprising a polymer having a SP value of 7 to 10 and a photopolymerization initiator is formed on a substrate made of an olefin resin, and the coating is applied after irradiating light on the coating layer On the layer, a heat-melt layer of a moisture-curable reactive hot melt adhesive having an isocyanate group-containing urethane prepolymer as a main component and a melting point of 40 ° C. or higher and 150 ° C. or lower is formed. A method for adhering an olefin resin, wherein a base material made of an olefin resin and an adherend are joined via a coating layer and the heat melting layer. The adhesion method according to claim 1, wherein the polymer having an SP value of 7 to 10 is a chlorinated polyolefin. The bonding method according to claim 1, wherein the polymer having an SP value of 7 to 10 is an acid-modified polyolefin.