JP2005171163A - 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 using a water-based emulsion-type primer and a moisture-curable reactive hot melt adhesive.

  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 base made of an olefin resin is coated with a water-based emulsion type primer mainly composed of an acid-modified olefin resin, and the primer is dried to coat the acid-modified olefin resin. Forming a layer, and forming a heat-melting layer of a moisture-curable reactive hot-melt adhesive having a melting point of 40 ° C. or higher and 150 ° C. or lower on the covering layer, the main component of which is an isocyanate group-containing urethane prepolymer, The second invention is a method for adhering an olefin resin, in which a base material made of an olefin resin and an adherend are joined via the coating layer of the acid-modified olefin resin and the heat-melting layer, and the second invention is drying in the first invention. When performing, it is an adhesion method of an olefin resin heated at a temperature of 60 to 180 ° C., and the third invention is the first invention or the second invention, the first invention or the second invention After drying in the invention, the water-based emulsion primer is used to irradiate the coating layer formed on the substrate made of the olefin resin with light, and then adhere using a moisture-curable reactive hot melt adhesive. This is an adhesion method.

When the base material made of an olefin resin is treated with a water-based emulsion-type primer mainly composed of an acid-modified olefin resin and bonded with a moisture-curable reactive hot melt adhesive, and the treatment with the primer is not performed. In comparison, a high adhesive force can be obtained, and a high adhesive force can also be obtained as compared with the case where treatment by plasma irradiation or corona discharge is performed.
Furthermore, higher adhesive force can be obtained by raising the drying temperature of the water-based emulsion type primer.
Moreover, a higher peel adhesion can be obtained by further irradiating the primer-coated surface with light.
In addition, by adopting an emulsion type as a primer and a solvent-free, moisture-curing reactive hot melt adhesive as an adhesive, an organic solvent can be used compared to the conventional solvent-type primer and solvent-type adhesive combination. This can improve problems such as ignition, danger of explosion, deterioration of working environment, and utility costs during solvent drying.
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.

Olefinic resin The olefinic resin used in the present invention is preferably an olefin polymer having 2 to 6 carbon atoms. As a preferred specific example, polyethylene, polypropylene (isotactic, syndiotactic, atactic) is used as a 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 (heat Plastic polyolefin) and the above materials with additives and fillers.
The ratio of the olefin component contained in the olefin resin in the present invention is 50% by mass or more, preferably 60% by mass or more.
Examples of other resin components contained in the olefin resin in the present invention include styrene resins, styrene elastomers, ethylene methacrylic acid resins, and ethylene vinyl acetate resins.

-Acid-modified olefin resin The acid-modified olefin resin in the present invention is an active ingredient of a water-based emulsion type primer applied to the surface of a substrate made of an olefin resin. Preferred acid-modified olefin resins are olefin resins modified with unsaturated carboxylic acids and / or acid anhydrides or acidic vinyl compounds.
The preferred olefin component used for the acid-modified olefin resin in the present invention is an olefin having 2 to 8 carbon atoms, and preferred specific examples include ethylene, propylene, butylene, heptene and octene.
Examples of unsaturated carboxylic acids or acid anhydrides used for modification include maleic acid, fumaric acid, itaconic acid, citraconic acid, allyl succinic acid, mesaconic acid, aconitic acid, and acid anhydrides thereof. Examples of the acidic vinyl compound include acrylic acid and methacrylic acid.
The acid-modified olefin resin in the present invention may be either crystalline or amorphous. In the case of crystallinity, the preferable melting point is 180 ° C. or lower, more preferably 150 ° C. or lower.
The acid-modified olefin resin in the present invention also includes acid-modified chlorinated polyolefin in which a part of hydrogen atoms in the olefin component of the acid-modified olefin resin is replaced with chlorine.

The preferable chlorine content of the acid-modified chlorinated polyolefin in the present invention is 1% by mass to 60% by mass, preferably 1% by mass to 50% by mass, and more preferably 1% by mass to 40% by mass.
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 water-based emulsion type primer in the present invention uses the acid-modified olefin resin as an active ingredient and is made into a water-based emulsion by a known method.
There is no restriction | limiting in particular in the density | concentration of an emulsion, What is necessary is just to have the viscosity which can be apply | coated.

Application method of primer The application method of the water-based emulsion type primer mainly composed of an acid-modified olefin resin may be any known method, and as a preferable example, it is applied by impregnating a brush, a nonwoven fabric, etc. with an appropriate amount. There are methods, roll coat, spray coat, dip and so on.

○ Drying method of primer As a drying method of an emulsion type primer mainly composed of an acid-modified olefin resin coated on an olefin resin, either natural drying by standing at room temperature or forced heating drying by hot air or the like can be applied.
When the outside air temperature is low, both the wettability may be reduced due to a decrease in the temperature of the substrate and the emulsion-type primer, or the wettability may be decreased due to a reduction in the pressing force of the coating.
In this way, when wetting between the primer and the substrate is not sufficiently achieved, the acid-modified olefin resin that has failed to wet is present on the olefin-based substrate. By heating, the wettability between the acid-modified olefin resin and the substrate can be enhanced.
A preferable drying method is heat drying, preferably 60 ° C. to 180 ° C., more preferably heat drying at a melting point of the acid-modified olefin resin to 150 ° C. According to this method, stable adhesiveness can be obtained without being affected by the ambient temperature of the workplace. 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 The light irradiation in the present invention is performed on the coating layer formed on the base material made of the olefin resin with the water-based emulsion type primer mainly composed of the acid-modified olefin resin after the drying. It has the effect of further improving the adhesiveness of a substrate made of an olefin resin.
Preferred electromagnetic wave irradiation is a UV and visible light 180～500Nm, preferred light irradiation amount is usually 100 mJ / cm ² or more, especially 200~10000mJ / cm ² is preferred.
Preferred light sources for light irradiation include a low-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp, and a metal halide lamp.
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 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 The olefin is passed through the coating layer of the acid-modified olefin 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. A base material made of a resin and an 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 x length of 50 mm x thickness of 2 mm, and a water-based emulsion type primer mainly composed of an acid-modified olefin resin on the surface of the substrate made of the olefin resin. After applying and drying, the following adhesive is applied to one side and 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.
In addition, the primer was dried by three methods: 2 minutes on an 80 ° C. heat plate, 3 minutes on a 90 ° C. heat plate, and natural drying 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 an aqueous emulsion-type primer mainly composed of an acid-modified olefin resin is formed on the surface of the base material made of the olefin resin. After applying and drying, with or without light irradiation, the following adhesive is applied to the treated surface, a cotton cloth is attached, pressed with heavy stone (5N / cm ² ) for 2 minutes, and 30 ° C 65 After curing for 3 days under the condition of% RH, 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]
A water-based emulsion type primer (manufactured by Nippon Paper Industries Co., Ltd., trade name: Supercron E-503, chlorine content: 14-15%, melting point: 60) ~ 70 ° C), dried on a heat plate at 80 ° C for 2 minutes, then applied with adhesive on one side, bonded and fixed with clips (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 according to JIS K 6850.

[Example 2]
Example 1 except that the emulsion-type primer mainly composed of maleic anhydride-modified chlorinated polyolefin was replaced by Nippon Paper Industries Co., Ltd. trade name Supercron E-603 (chlorine content: 17%, melting point: 80-90 ° C.) The tensile shear bond strength between substrates made of an olefin resin was measured by the same method.

[Example 3]
Example except that the water-based emulsion type primer mainly composed of maleic anhydride-modified chlorinated polyolefin was replaced by Nippon Paper Industries Co., Ltd. trade name Supercron E-723 (chlorine content 19%, melting point 70-80 ° C.) 1 was used to measure the tensile shear bond strength between substrates made of an olefin resin.
The results of Examples 1 to 3 are shown in Table 1 below.

[Example 4]
The water-based emulsion type primer mainly composed of maleic anhydride-modified chlorinated polyolefin is replaced with Toyo Kasei Kogyo Co., Ltd. trade name HARDEN EH-801 (chlorine content: 16%, melting point: 87 ° C.), and the drying conditions are 90 ° C. 3 The tensile shear bond strength between substrates made of an olefin resin was measured in the same manner as in Example 1 except that the time was changed to minutes.
In addition, the primer is applied to the surface of a base material made of olefin resin, dried on a heat plate at 90 ° C. for 3 minutes, then an adhesive is applied to the treated surface, a cotton cloth is bonded, and 2 minutes with a heavy stone. The film was pressed (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.

[Example 5]
After drying the water-based emulsion type primer, the tensile shear adhesive strength and peel adhesive strength were measured in the same manner as in Example 4 except that light was irradiated.

[Example 6]
The tensile shear bond strength was measured by the same method as in Example 4 except that drying was performed at room temperature.
The results of Examples 4 to 6 are shown in Table 2 below.

[Example 7]
Tensile shear strength between substrates made of olefin resin in the same manner as in Example 1 except that the water-based emulsion type primer mainly composed of acid-modified olefin resin was replaced by Nippon Paper Industries Co., Ltd. trade name Auroren 6008. Was measured.

[Comparative Example 1]
The surface of the base material made of the olefin resin is not treated at all, and an adhesive is applied to one side of the base material 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 2]
Toluene is applied to the surface of a base material made of olefin resin and dried on a heat plate at 80 ° C. for 2 minutes, and then adhesive is applied to one side and bonded together, 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 according to JIS K 6850.

[Comparative Example 3]
After irradiating the surface of the base material made of olefin resin with a plasma irradiation device under conditions of an irradiation distance of 6 mm and an irradiation time of 3 seconds, an adhesive is applied on one side and bonded together, and then clipped. (Adhesion 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.
As the plasma irradiation apparatus, ST-7000 manufactured by Keyence Corporation was used.

[Comparative Example 4]
After corona discharge is performed on the surface of the base material made of olefin resin under the conditions of an irradiation distance of 5 mm and an irradiation time of 15 seconds with a corona discharge device, an adhesive is applied on one side and bonded together, and then clipped. (Adhesion 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.
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)

An aqueous emulsion-type primer mainly composed of an acid-modified olefin resin is applied to a base material made of an olefin resin, and the primer is dried to form a coating layer of the acid-modified olefin resin. And forming a heat-melting 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 more and 150 ° C. or less, and the acid-modified olefin resin coating layer and A method for adhering an olefin-based resin in which a base material made of an olefin-based resin and an adherend are joined via a hot-melt layer. A method for adhering an olefin resin, wherein the olefin resin is heated at a temperature of 60 to 180 ° C when drying according to claim 1. After drying according to claim 1 or 2, the coating layer formed on the substrate made of the olefin resin is irradiated with light by a water-based emulsion type primer, and then a moisture curable reactive hot melt adhesive is applied. The method for adhering an olefin-based resin according to claim 1 or 2, wherein the olefin-based resin is adhered using the method.