JP2016196626A - Reactive hot melt composition for automobile lamp tool and automobile lamp fitting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactive hot melt composition for automobile lamp fittings, capable of preventing a fogging phenomenon of whitely clouding the inner surface of a cover made of a polycarbonate resin to reduce transparency as a whole from occurring even when used for bonding a housing part constituting an automobile lamp fitting portion to a lens part made of a polycarbonate resin or the like covering the front of the housing part, and an automobile lamp fitting.SOLUTION: The reactive hot melt composition for automobile lamp fittings consists of a polyisocyanate, a polyester polyol, a polyether polyol and at least one of an acrylic polyol and an acrylic resin. The acrylic polyol and the acrylic resin are obtained by polymerizing an acrylic monomer with an azo polymerization initiator having an azo decomposition product evaporation rate of 20-100 mg/hr cmat 70°C and a chain transfer agent having a molecular weight of 200-1000, and an automobile lamp fitting uses the same.SELECTED DRAWING: None

Description

  The present invention relates to a reactive hot melt composition for automobile lamps used for bonding between a housing part constituting a lamp part of an automobile and a lens part made of polycarbonate resin or the like covering the front surface thereof, and the housing part using the composition. And an automotive lamp having a lens part bonded thereto.

  Conventionally, the housing part constituting the lamp part of an automobile and the lens part covering the front face have high mechanical strength such as impact strength, heat stability, excellent weather resistance, and excellent transparency. Polycarbonate resins are widely used. Examples of the reactive hot melt adhesive used for bonding the polycarbonate resin lens part and the housing part include a polyol containing a crystalline aliphatic polyester diol (a1) and an aliphatic polyether polyol (a2). It is characterized by comprising (a) an isocyanate group-terminated urethane prepolymer (A) obtained by reacting polyisocyanate (b), a morpholine ring-containing compound (B) and a compound having a carboxyl group (C). A reactive hot melt adhesive is proposed (Patent Document 1).

JP 2009-286883 A

  However, when the reactive hot melt adhesive is used for bonding a housing part constituting a lamp part of an automobile and a lens part made of polycarbonate resin or the like covering the front surface thereof, the inner surface of the lens made of polycarbonate resin or the like is used. There is a problem that a fogging phenomenon may occur in which the cloudiness is white and the transparency is lowered as a whole.

  In particular, since there are many kinds of chemical materials constituting the reactive hot melt adhesive, the causative substance cannot be easily identified, and the problem cannot be solved for many years. The inventor according to the present application has intensively studied to solve the problem, and as a result, investigated the cause of the fogging phenomenon and completed the present invention.

  The problem to be solved by the present invention is that the inner surface of the polycarbonate resin cover is white even if it is used for bonding the housing portion constituting the lamp portion of the automobile and the lens portion made of polycarbonate resin or the like covering the front surface thereof. An object of the present invention is to provide a reactive hot melt composition for an automotive lamp and an automotive lamp that are not fogged and do not cause a fogging phenomenon in which the transparency is lowered as a whole.

In order to solve the above problems, the invention according to claim 1 of the present application is composed of a polyisocyanate, a polyester polyol, a polyether polyol, and at least one of an acrylic polyol and an acrylic resin. Reactive hot for automotive lamps characterized in that an acrylic monomer is polymerized with an azo polymerization initiator having an azo decomposition product evaporation rate of 70 to 100 mg / hr · cm ² at 70 ° C. and a chain transfer agent having a molecular weight of 200 to 1000 A melt composition is provided.

  The invention according to claim 2 provides the reactive hot melt composition for automobile lamps according to claim 1, wherein the weight average molecular weight of the acrylic polyol and the acrylic resin is 15000 to 60000.

  The invention according to claim 3 provides the reactive hot melt composition for automotive lamps according to claim 1 or 2, wherein the acrylic polyol has a hydroxyl value of 2 to 20 mgKOH / g.

  In the invention according to claim 4, the acrylic polyol is polymerized using at least one of methyl methacrylate (MMA), butyl methacrylate (BMA), or 2-hydroxyethyl methacrylate (2-HEMA) as a monomer component, and an acrylic resin is obtained. The reactive hot for automobile lamps according to any one of claims 1 to 3, wherein at least one of methyl methacrylate (MMA) and butyl methacrylate (BMA) is polymerized as a monomer component. A melt composition is provided.

  The invention for claim 5 is characterized in that the azo polymerization initiator is 2,2'-azobis (isobutyric acid) dimethyl, the reaction for an automobile lamp according to any one of claims 1 to 4. A hot melt composition is provided.

The invention according to claim 6 provides the reactive hot melt composition for automobile lamps according to any one of claims 1 to 5, wherein the chain transfer agent is a mercapto group-containing compound. .

  The invention according to claim 7 is an automobile lamp characterized in that a lens part and a housing part are bonded with the reactive hot melt composition for an automobile lamp according to any one of claims 1 to 6. provide.

  The reactive hot melt composition for automobile lamps according to the present invention causes the fogging phenomenon even when used for bonding a housing part constituting a lamp part of an automobile and a lens part made of polycarbonate resin or the like covering the front surface thereof. There is an effect that there is nothing to do.

  Moreover, since the reactive hot melt composition for automobile lamps according to the present invention has a low viscosity, it has an effect of being excellent in coatability and having good initial adhesiveness.

  In addition, the automotive lamp in which the housing part constituting the lamp part of the car and the lens part made of polycarbonate resin or the like covering the front surface thereof is bonded with the reactive hot melt composition for the car lamp according to the present invention has the same fogging phenomenon as described above. There is an effect that it does not occur.

  Hereinafter, the reactive hot melt composition for automobile lamps and the automobile lamp of the present invention will be described in detail.

The reactive hot melt composition for automobile lamps of the present invention comprises a polyisocyanate, a polyester polyol, a polyether polyol, and at least one of an acrylic polyol and an acrylic resin, and the acrylic polyol and the acrylic resin contain an acrylic monomer. A reactive hot melt composition for automobile lamps, polymerized by an azo polymerization initiator having an azo decomposition product evaporation rate of 20 to 100 mg / hr · cm ² and a chain transfer agent having a molecular weight of 200 to 1000, and the like. Antioxidants, ultraviolet absorbers, light stabilizers, other tackifiers, colorants, pigments, fillers, defoaming agents, foaming inhibitors, catalysts, and the like can be added.

Polyisocyanate Polyisocyanate used in the present invention is a bifunctional or higher polyisocyanate, C (excluding carbon in the NCO group, the same shall apply hereinafter) 6-20 aromatic polyisocyanate, C2-18 aliphatic polyisocyanate. Isocyanates, C4-15 alicyclic polyisocyanates, C8-15 araliphatic polyisocyanates, or modified products of these polyisocyanates and mixtures of two or more of these can be used.

  Aromatic polyisocyanates include diisocyanates [1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate (TDI), 2,4′- and / or 4 , 4′-diphenylmethane diisocyanate (MDI), 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-di Isocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, m- and p-isocyanatophenylsulfonyl isocyanate, etc.] trifunctional or higher polyisocyanate [4,4 ′, 4 ″ -triphenylmethane triisocyanate, crude TDI, crude MDI etc.].

  Aliphatic polyisocyanates include diisocyanates [ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcapro. Acid, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, etc.], triisocyanate [2-isocyanatoethyl-2,6-diisocyanatohexanoate, 1,6,11 -Undecane triisocyanate etc.] etc. can be mentioned.

  Examples of alicyclic-containing polyisocyanates include diisocyanates [isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis (2-isocyanate). Natoethyl) -4-cyclohexene-1,2-dicarboxylate, 2,5- and / or 2,6-norbornane diisocyanate and the like], triisocyanate [bicycloheptane triisocyanate and the like] and the like.

  Examples of the araliphatic polyisocyanate include diisocyanate [m- and / or p-xylylene diisocyanate (XDI), α, α, α ′, α′-tetramethylxylylene diisocyanate (TMXDI), etc.]. .

  In addition, modified polyisocyanates include modified polyisocyanates such as modified (urethane modified, carbodiimide modified, trihydrocarbyl phosphate modified, etc.) MDI, urethane modified TDI, biuret modified HDI, isocyanurate modified HDI, isocyanurate modified IPDI and the like. And a mixture of two or more of these [for example, combined use of modified MDI and urethane-modified TDI (isocyanate group-containing prepolymer)].

  Among the above polyisocyanates, HDI, IPDI, TDI, MDI, XDI, TMXDI, hydrogenated MDI, and hydrogenated TDI are preferable in terms of adhesiveness, and HDI, MDI and a mixture thereof are more preferable.

Polyester polyol As the polyester polyol used in the present invention, those formed by condensation of an aliphatic dihydric alcohol and an aliphatic (saturated or unsaturated) dicarboxylic acid can be used.

  Examples of the aliphatic dihydric alcohol include {carbon number (hereinafter abbreviated as C) 2 to 20, such as aliphatic [ethylene glycol, diethylene glycol, 1,2-propylene glycol, dipropylene glycol, 1,2-, 1,3- And 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,3-, 1,4-, 1,6- and 2,5-hexanediol, 1,2- and 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,18-octadecanediol, 1,20-eicosanediol, etc.], alkyl (C1-3) dialkanolamine and the like}. Of these, 1,4-butanediol, 1,6-hexanediol, and 1,9-nonanediol are preferable in terms of adhesiveness.

  As the aliphatic dicarboxylic acid, C2-24 as saturated aliphatic dicarboxylic acid, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, methyl succinic acid, dimethyl malonic acid, β-methyl glutaric acid, ethyl succinic acid, isopropyl malonic acid. Adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, hexadecanedicarboxylic acid, octadecanedicarboxylic acid and eicosandicarboxylic acid. Examples of unsaturated aliphatic dicarboxylic acids include C4-24, such as maleic acid, fumaric acid, citraconic acid and mesaconic acid. Of these, adipic acid and sebacic acid are preferred in terms of adhesion and crystallinity.

Polyether polyol The polyether polyol used in the present invention is preferably an aliphatic polyether polyol, for example, water or alcohol added with an alkylene oxide, such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol. I can do it.

  The weight ratio of the polyester polyol and the acrylic polyol or acrylic resin is preferably 10/100 to 100/10, and if it is less than 10/100, the viscosity is high and the workability is poor, and if it exceeds 100/10, the strength tends to decrease. . More preferably, it is 10/100 to 100/100. If it is less than 10/100, the viscosity tends to increase, and if it exceeds 100/100, the strength tends to decrease.

  The weight ratio of the polyester polyol to the polyether polyol is preferably 10/100 to 100/10, and if it is less than 10/100, the strength decreases, and if it exceeds 100/10, the viscosity increases. More preferably, it is 10/100 to 100/100. If it is less than 10/100, the strength tends to decrease, and if it exceeds 100/100, the strength tends to decrease.

  The reactive hot melt composition for automobile lamps of the present invention comprises a terminal isocyanate urethane prepolymer obtained by reacting an excess of a polyisocyanate with a polyester polyol, an acrylic polyol, and a polyether polyol. The equivalent ratio of isocyanate groups to hydroxyl groups in the urethanization reaction of polyisocyanate and these polyols is preferably 1/1 to 2/1 from the viewpoint of adhesiveness and melt viscosity, and 1.3 / 1 to 1.7 / 1. More preferred.

  The reaction between the excess polyisocyanate, the polyester polyol, the acrylic polyol, and the polyether polyol is performed by first thoroughly mixing the polyester polyol, the acrylic polyol, and the polyether polyol, and then reacting the mixture with the polyisocyanate.

Acrylic polyol The acrylic polyol and the acrylic resin used in the present invention are an azo polymerization initiator having an azo decomposition product evaporation rate of 70 to 100 ° C. of 20 to 100 mg / hr · cm ² and a chain transfer agent having a molecular weight of 200 to 1000. Acrylic polyol or acrylic resin polymerized by. The azo decomposition product evaporation rate (dM / dt) is uniformly 10 mg of azo polymerization initiator in a measurement cell SUS (5 mmφ × 5 mm: bottom area: 0.196 cm ² ) of TG-DTA (simultaneous differential thermal and thermogravimetric measurement device). The weight change (mg / hr · cm ² : dM / dt) was sequentially measured at a temperature rising rate of 10 ° C./hr, and the evaporation rate equation was obtained by the following equation (linear regression (least square method) ) To calculate the slope B and intercept A), and substituting 70 ° C. (absolute temperature K343 ° C.) into the obtained evaporation rate equation.
Evaporation rate formula: log (dM / dt) = AB / TA, B: coefficient, T: absolute temperature (K)

  The weight average molecular weight by the GPC method of the acrylic polyol and acrylic resin polymerized by the azo polymerization initiator and a chain transfer agent having a molecular weight of 200 to 1000 is 15000 to 60000, more preferably 15000 to 40000. If the weight average molecular weight is less than 15000, fogging may occur. If it exceeds 60,000, the viscosity of the composition becomes high and the coating workability becomes poor. If it exceeds 40,000, the coating workability tends to be poor.

  The acrylic polyol is a copolymer of (meth) acrylic acid [alkyl (C1-30)] ester [methyl (meth) acrylate etc.] and a hydroxyl group-containing acrylic monomer [hydroxyethyl (meth) acrylate etc.], etc. Preferably, the polymerization is performed using at least one of methyl methacrylate (MMA), butyl methacrylate (BMA), or 2-hydroxyethyl methacrylate (2-HEMA) as a monomer component. The hydroxyl value is preferably 2 to 20 mgKOH / g. If it is less than 2 mgKOH / g, the adhesive strength is insufficient, and if it exceeds 20 mgKOH / g, the cured product may be too hard. The acrylic resin is used for imparting tackiness, and at least an alkyl or alkenyl (meth) acrylate and a (co) polymer such as acrylic acid can be used. Preferably, at least methyl methacrylate (MMA) is used. Alternatively, polymerization is performed using either butyl methacrylate (BMA) as a monomer component.

Azo polymerization initiators, azo decomposition products evaporation rate of preferably 20~100mg / hr · cm ^2, occurs fogging is less than 20mg / hr · cm ^2, the workability during the polymerization at 100mg / hr · cm ² greater Becomes defective. As a polymerization initiator having an azo decomposition product evaporation rate of 20 to 100 mg / hr · cm ² , there is 2,2′-azobis (isobutyric acid) dimethyl (azo decomposition product evaporation rate: 25 mg / hr · cm ² ).

  The chain transfer agent used in the polymerization preferably has a molecular weight of 200 to 1000. If the molecular weight is less than 200, fogging occurs, and if it exceeds 1000, the workability during polymerization becomes poor. An example of a chain transfer agent having a molecular weight of 200 to 1000 is pentaerythritol tetrakis (3-mercaptopropionate) (molecular weight 488).

  In addition, the automotive lamp according to claim 7 is a reactive hot melt composition for an automotive lamp according to any one of claims 1 to 6 made of the above material, and a lens part such as a headlamp of an automobile or a rear lamp. This is an automotive lamp having a housing part that supports it bonded thereto.

  Hereinafter, the reactive hot melt composition for automobile lamps according to the present application will be specifically described with reference to Examples and Comparative Examples.

Examples and Comparative Examples Millionate MT (trade name, manufactured by Tosoh Corp., NCO wt%: 33.6 wt%) as MDI is used as the polyisocyanate, and HS 2H-451A (trade name, manufactured by Toyokuni Seiyaku Co., Ltd., adipine) is used as the polyester polyol. Crystalline polyester polyol obtained by esterification reaction of acid and 1,6 hexanediol, molecular weight: 4500) is used as polyether polyol, using ADEKA polyether P-2000 (trade name, manufactured by ADEKA, molecular weight: 2000) did. Moreover, acrylic resin and acrylic polyol use acrylic resin A, acrylic resin B, acrylic resin C, acrylic resin D, acrylic resin E, acrylic polyol A, and acrylic polyol B prepared by the following procedure. In the composition shown in Fig. 2, materials other than polyisocyanate are put into a separable flask equipped with a stirrer, a temperature control device, and a vacuum pump, and stirred and dehydrated at 120 ° C under reduced pressure for 2 hours. In addition, the reaction was carried out by stirring for 2 hours at 110 ° C. in a nitrogen atmosphere, and reactive hot melt compositions for automobile lamps of Examples and Comparative Examples that were solid at room temperature were obtained.

<Acrylic resin A>
Methyl methacrylate 70.32 parts by weight, n-butyl methacrylate 29 parts by weight, methacrylic acid 0.68 parts, 2,2′-azobis (isobutyric acid) dimethyl as a polymerization initiator (azo decomposition product evaporation rate: 25 mg / hr -Cm2) 5 parts by weight, ² parts by weight of pentaerythritol tetrakis (3-mercaptopropionate) (molecular weight 488) as a chain transfer agent are mixed and dissolved to prepare a monomer solution. Next, in a separable flask equipped with a stirrer and a reflux condenser, 190 parts by weight of water, an anionic surfactant PRISERV A210G (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene phosphate ester surfactant) Add 0.01 parts by weight and 50 parts by weight of a slurry of 10% by weight of tribasic calcium phosphate as a dispersant for suspension polymerization and mix uniformly. Next, the monomer solution is added and the monomer is dispersed with a stirrer. While confirming the particle diameter with a microscope, the stirring speed is increased, and when the target particle diameter is reached, the stirring speed is decreased and heating is started. The reaction is carried out at 70 ° C. for 2 hours, and after confirming that the heat generated by the polymerization has subsided, the mixture is further heated at 85 ° C. for 3 hours to complete the polymerization. After completion of the polymerization, the mixture is cooled to 40 ° C., and 10 parts of concentrated hydrochloric acid is added to dissolve the tricalcium phosphate. After dehydrating and taking out the particles, the particles were dried at 70 ° C. for 12 hours to obtain particulate acrylic resin A. The weight average molecular weight by GPC method of the obtained acrylic resin A was 32000, and the weight average molecular weight / number average molecular weight was 1.6.

<Acrylic resin B>
A particulate acrylic resin B obtained in the same manner as the polymerization of the acrylic resin A was obtained except that thiosalicylic acid (molecular weight 154) was used instead of the chain transfer agent used in the polymerization of the acrylic resin A. The weight average molecular weight by GPC method of the obtained acrylic resin B was 35000, and the weight average molecular weight / number average molecular weight was 1.6.

<Acrylic resin C>
The particulate acrylic resin C obtained in the same manner as the polymerization of the acrylic resin A was used except that benzoyl peroxide was used instead of the polymerization initiator used in the polymerization of the acrylic resin A. The weight average molecular weight of acrylic resin C obtained by the GPC method was 35000, and the weight average molecular weight / number average molecular weight was 1.6.

<Acrylic resin D>
Similar to polymerization of acrylic resin A except that 1.7 parts by weight of tetraethylene glycol bis (3-mercaptopropionate) (molecular weight 372) was used instead of the chain transfer agent used in the polymerization of acrylic resin A. Thus obtained particulate acrylic resin D was obtained. The weight average molecular weight of acrylic resin D obtained by the GPC method was 28000, and the weight average molecular weight / number average molecular weight was 1.6.

<Acrylic resin E>
Similar to the polymerization of acrylic resin A, except that 1.3 parts by weight of 2-ethylhexyl-3-mercaptopropionate (molecular weight 218) was used instead of the chain transfer agent used in the polymerization of acrylic resin A. The obtained particulate acrylic resin E was obtained. The weight average molecular weight of acrylic resin E obtained by the GPC method was 26000, and the weight average molecular weight / number average molecular weight was 1.9.

<Acrylic polyol A>
68.25 parts by weight of methyl methacrylate, 27.9 parts by weight of n-butyl methacrylate, 2.55 parts by weight of 2-hydroxyethyl methacrylate (2-HEMA), 2,2′-azobis (isobutyric acid) as a polymerization initiator 5 parts by weight of dimethyl (azo decomposition product evaporation rate: 25 mg / hr · cm ² ), ² parts by weight of pentaerythritol tetrakis (3-mercaptopropionate) (molecular weight 488) as a chain transfer agent are mixed and dissolved to prepare a monomer solution. To do. Then, after reacting in the same manner as acrylic resin A, it was dried at 60 ° C. for 12 hours to obtain particulate acrylic polyol A. The weight average molecular weight by GPC method of the obtained acrylic polyol A was 26000, and the weight average molecular weight / number average molecular weight was 1.5.

<Acrylic polyol B>
A particulate acrylic polyol B was obtained in the same manner as the polymerization of the acrylic polyol A except that thiosalicylic acid (molecular weight 154) was used instead of the chain transfer agent used in the polymerization of the acrylic polyol A. The resulting acrylic polyol B had a weight average molecular weight of 28000 and a weight average molecular weight / number average molecular weight of 1.6 by GPC method.

Evaluation items and evaluation methods Evaluation items and evaluation methods are shown below.

Viscosity Using a Brookfield viscometer, 15 g of the reactive hot melt composition for automobile lamps of Examples or Comparative Examples was melted at 120 ° C., measuring temperature: 120 ± 1 ° C., spindle No. 29, rotation speed at the time of measurement : Viscosity (Pa · s) immediately after holding at 10 rpm for 30 minutes was measured.

The groove of the initial adhesive upper part is opened, the groove width of the opened groove is 5 mm, the depth is 20 mm, and the groove of the polypropylene jig having a U-shaped surface treatment in front view, The reactive hot melt composition for automobile lamps of Examples or Comparative Examples was heated to 120 ° C. and immediately filled with a polycarbonate flat plate having a thickness of 2 mm, a depth of 20 mm, and a height of 50 mm in the center of the groove when viewed from the front. Insert it in parallel with the groove until it touches the bottom of the groove. At the time of insertion, the hot melt composition protruding from the groove is carefully removed. Thereafter, it was cured at 23 ° C. for 168 hours, and the inserted polycarbonate flat plate was pulled upward at 23 ° C. or 90 ° C. at 50 mm / second, and the tensile strength (N) at that time was measured. At 23 ° C., 900N or more was evaluated as ◯, and less than 900N was evaluated as ×. At 90 ° C., 100N or more was evaluated as ◯, and less than 100N was evaluated as ×.

Fogging property The reactive hot melt composition for automobile lamps of Examples or Comparative Examples is heated to 120 ° C. to prepare a sheet having a thickness of 2 mm and a diameter of 80 mm and cured at 23 ° C. and 50% RH for 7 days. The sheet is placed in a flask, and the mouth of the flask is sealed with a perforated glass plate. Next, the glass hole is sealed with a polycarbonate plate having a thickness of 3 mm. Further, the lower part of the flask is heated at 120 ° C. for 24 hours, and the presence or absence of adhesion of volatile substances to the polycarbonate plate is visually confirmed. The thing which did not adhere | attach was set as (circle), and it evaluated as x when the other solid substance and liquid substance had adhered.

  The evaluation results are shown in Tables 3 and 4.

Claims (7)

It consists of polyisocyanate, polyester polyol, polyether polyol, and at least one of acrylic polyol and acrylic resin. The acrylic polyol and acrylic resin have an azo decomposition product evaporation rate at 70 ° C. of 20 to 100 mg / hr. A reactive hot melt composition for automobile lamps, which is polymerized with a cm ² azo polymerization initiator and a chain transfer agent having a molecular weight of 200 to 1,000.   The reactive hot melt composition for an automotive lamp according to claim 1, wherein the weight average molecular weight of the acrylic polyol and the acrylic resin is 15000 to 60000.   The reactive hot melt composition for an automotive lamp according to claim 1 or 2, wherein the acrylic polyol has a hydroxyl value of 2 to 20 mgKOH / g.   The acrylic polyol is polymerized using at least methyl methacrylate (MMA) or butyl methacrylate (BMA) or 2-hydroxyethyl methacrylate (2-HEMA) as a monomer component, and the acrylic resin is at least methyl methacrylate (MMA) or The reactive hot melt composition for automobile lamps according to any one of claims 1 to 3, wherein any of butyl methacrylate (BMA) is polymerized as a monomer component.   The reactive hot melt composition for an automotive lamp according to any one of claims 1 to 4, wherein the azo polymerization initiator is 2,2'-azobis (isobutyric acid) dimethyl.   The reactive hot melt composition for an automotive lamp according to any one of claims 1 to 5, wherein the chain transfer agent is a mercapto group-containing compound.   A lens part and a housing part are bonded with the reactive hot melt composition for an automobile lamp according to any one of claims 1 to 6.