JP4581389B2 - Adhesion method of olefin resin - Google Patents

Description

  The present invention relates to a method for bonding an olefin resin. Specifically, after applying a solution-type primer containing chlorinated polyolefin as a main component to an olefin resin and drying it, the adhesion of the olefin resin was improved, and then the melting point of the urethane prepolymer containing an isocyanate group as a main component. A method of adhering an olefin resin characterized by using a moisture-curable reactive hot melt adhesive having a temperature of 40 ° C. or higher and 150 ° C. or lower, and a solution-type primer mainly composed of chlorinated polyolefin applied to the olefin resin. After drying and irradiating with light, the adhesiveness of the olefin resin is further improved, and then the moisture-curable reactive hot 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. The present invention relates to a method for adhering an olefin resin characterized by using a melt adhesive.

  2. Description of the Related Art In recent years, in the automobile industry and the building materials industry, with the goal of reducing the weight of components and reducing the environmental burden, products that have been manufactured with steel or vinyl chloride resin have been replaced with olefin resins. 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 in 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 object of the present invention is to reduce the amount of organic solvent gas generated in the bonding operation by improving the above-mentioned drawbacks, that is, by changing the adhesive from a solvent type to a solventless type, and at the same time, adhesion to an olefin-based substrate is reduced by plasma irradiation. It is another object of the present invention to provide an adhesion method that makes the adhesion improvement level higher than that of corona discharge.

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, the first invention in the present invention was formed by applying a solution-type primer mainly composed of chlorinated polyolefin to a base material made of an olefin resin , drying the primer, and then forming the solution-type primer. The coating layer is irradiated with light, and then 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 resin bonding method in which a base material made of an olefin resin and an adherend are bonded via the coating layer of the chlorinated polyolefin and the heat melting layer, and the second invention is the first invention A drying method is an adhesion method of an olefin resin characterized by drying at a temperature of 60 to 180 ° C.

Adhesive strength is higher than that of no treatment by treating a substrate made of olefin resin with a solution-type primer composed mainly of chlorinated polyolefin and then adhering it with a moisture-curable reactive hot melt adhesive. In addition, high adhesive force can be obtained as compared with plasma irradiation and corona discharge.
Furthermore, higher adhesive force can be obtained by raising the drying temperature of the primer.
Moreover, a higher peel adhesion can be obtained by further irradiating the primer-coated surface with light.
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.

-Chlorinated polyolefin The chlorinated polyolefin in this invention is an active ingredient of the solution type primer applied to the surface of the substrate which consists of olefin resin. Preferred chlorinated polyolefins in the present invention are chlorinated polyolefins having 2 to 8 carbon atoms, chlorinated polyethylene, chlorinated polypropylene, chlorinated polybutylene, chlorinated ethylene-propylene copolymer, chlorinated ethylene- Butylene copolymer, chlorinated ethylene-vinyl acetate copolymer, maleic anhydride-modified chlorinated polyethylene, maleic anhydride-modified chlorinated polypropylene, maleic anhydride-modified chlorinated polybutylene, maleic anhydride-modified chlorinated polyethylene -A propylene copolymer etc. can be mentioned, However, It is not limited to these.

The preferable chlorine content of the chlorinated polyolefin in the present invention is 1% by mass or more and 60% by mass or less, and more preferably 1% by mass or more and 50% by mass or less.
If the chlorine content is less than 1% by mass or exceeds 60% by mass, the adhesion of the polyolefin resin to the adhesive may be reduced. The cause is presumed that when the chlorine content is low, the wettability of the chlorinated polyolefin to the adhesive is reduced, and when the chlorine content is high, the wettability of the chlorinated polyolefin to the polyolefin resin is reduced. The

The solution-type primer in the present invention is a solution obtained by using the above chlorinated polyolefin as an active ingredient and a known solvent.
There is no restriction | limiting in particular in the density | concentration of chlorinated polyolefin, What is necessary is just to have the viscosity which can be apply | coated.

○ Primer application methods Solution primer methods based on chlorinated polyolefins include brush, non-woven fabric, etc., impregnated in appropriate amounts, roll coat, spray coat, dip, etc. Not what you want.

○ Drying method of primer The drying method of solution-type primer mainly composed of chlorinated polyolefin coated on olefin resin can be applied to either natural drying or forced heating drying with hot air, etc., but the outside air temperature is low. In some cases, the wettability of the substrate and the solution-type primer may be reduced due to a decrease in temperature, the wettability to the substrate may be reduced due to the type of solvent, or the wettability may be reduced due to a reduction in the pressing force of the coating.
When wetting in the solution state is not sufficiently achieved in this way, the chlorinated polyolefin that has failed to wet will be present on the olefin-based substrate, but by heating the chlorinated polyolefin at 60 ° C. or higher. The wettability between the chlorinated polyolefin and the substrate can be improved.
Therefore, it is preferable to heat and dry at 60 ° C. to 180 ° C., more preferably at a softening point of chlorinated polyolefin to 150 ° C. rather than natural drying, in order to obtain stable adhesiveness that is not affected by the ambient temperature in the workplace. Is desirable. 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.

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 preferable 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, if 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 Olefin-based via the coating layer of chlorinated polyolefin formed on the surface of the substrate made of olefin-based resin and the heat-melting layer of moisture-curable reactive hot-melt adhesive as described above The base material made of 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.

○ 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 solution-type primer containing chlorinated polyolefin as the main component is applied to the surface of the substrate made of the olefin resin. Then, after drying and with or without light irradiation, the following adhesive is applied on 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.
Moreover, the drying of the primer was evaluated by two methods, ie, when it was performed on a 60 ° C. heat plate for 3 minutes and when it was naturally dried at room temperature.

○ 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 solution-type primer mainly composed of chlorinated polyolefin is applied to the surface of the base material made of the olefin resin. After drying, with or without light irradiation, apply the following adhesive to the treated surface, attach cotton cloth, press for 2 minutes with heavy stone (5N / cm ² ), 30 ° C 65% RH After curing for 3 days, the 180 ° peel strength was measured according to JIS K 6854-2.
The primer was dried on a 90 ° C. heat plate for 3 minutes.
[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 INC. With an output of 3.2 kW, and the irradiation energy was 2000 mJ / cm ² as measured by an integrating light meter with a wavelength of 365 nm.

[Example 1]
As a solution-type primer mainly composed of chlorinated polypropylene on the surface of the olefin resin, Super Clon (registered trademark) 822 (chlorine content 24.5%, softening point 70 to 80 ° C.) manufactured by Nippon Paper Industries Co., Ltd. is applied. After drying on a heat plate at 60 ° C. for 3 minutes, 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 in accordance with JIS K 6850, and the adhesive fracture surface was visually evaluated.
Also, the peel adhesion strength is that the primer is applied to the surface of the olefin resin, dried on a heat plate at 90 ° C. for 3 minutes, then the adhesive is applied to the treated surface, the cotton cloth is bonded, and the weight is 2 minutes. The film was pressed (5 N / cm ² ), cured for 3 days under the conditions of 30 ° C. and 65% RH, and the peel adhesion strength was measured according to JIS K 6854.
[Example 2]
The solution-type primer was adhered by the same method as in Example 1 except that it was naturally dried at room temperature, and the adhesion strength between the olefin resins was measured.

[Example 3]
After drying the solution-type primer, the tensile shear adhesive strength and peel adhesive strength were measured in the same manner as in Example 2 except that light was irradiated.
[Comparative Example 1]
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 conditions of 30 ° C. and 65% RH, the tensile shear bond strength was measured according to JIS K 6850.

[Comparative Example 2]
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 fixed with a clip (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 3]
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 a clip (adhesion area width 25 mm × length 12.5 mm). The film was cured at 30 ° C. and 65% RH for 3 days, and the tensile shear bond strength was measured in accordance with JIS K 6850.
As the plasma irradiation apparatus, ST-7000 manufactured by Keyence Corporation was used.

[Comparative Example 4]
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 and reduction of environmental burdens of members.
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 (2)

After applying a solution-type primer mainly composed of chlorinated polyolefin to a substrate made of an olefin resin , drying the primer, irradiating the coating layer formed by the solution-type primer with light, and then applying the coating 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, and the coating layer of the chlorinated polyolefin And an adhesion method of the olefin resin, in which the base material made of the olefin resin and the adherend are joined via the hot melt layer. The method for adhering an olefin resin, wherein the drying method according to claim 1 is performed at a temperature of 60 to 180 ° C.