JP2009067916A - Body sealer for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve various required properties by effecting photocuring before a thermal curing step by a simple formulation, using a material being friendly to environment. <P>SOLUTION: The body sealer for automobiles comprises, as essential ingredients, a photopolymerizable component and a thermoplastic resin. A preferable form of the monomer or the oligomer as the polymerizable component is a derivative of acrylic acid or methacrylic acid. The suitable compounding ratio of the monomer or the oligomer as the polymerizable component is 0.5-50 pts.wt. relative to 100 pts.wt. of the whole amount of the body sealer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an adhesive by organic synthesis, in particular, an automotive adhesive for joining panels such as metal plates, and more particularly to an automotive adhesive called a body sealer.

  After applying the body sealer to the panel joint, a finish paint is overcoated thereon. Since the body sealer is required to be smooth-finished because the paint is overcoated thereon, it is desirable that the body sealer has a low viscosity, good application workability, and is cured in a relatively low temperature region. Therefore, as the body sealer, resins such as vinyl chloride resin, copolymer resins of vinyl chloride and other materials, acrylic resins, methacrylic resins, or acrylic and methacrylic copolymer resins (acrylic-methacrylic copolymer resins) An organosol-type thermoplastic resin comprising the above powder and its plasticizer is used.

  The body sealer needs to be temporarily cured before the paint is overcoated. Since the heating method is generally employed for the temporary curing, it is desired to shorten the process and save energy in the painting area of the factory. However, each of the previous attempts has drawbacks and has not yet solved this problem.

  There is a method of using a solvent to increase the viscosity due to volatilization after application, but it is not realistic because it is contrary to the VOC (volatile organic compound) regulations of the automobile industry.

  A method referred to as hot apply is a method in which a high-viscosity adhesive is heated to a viscosity that can be applied at room temperature and returned to a high viscosity when cooled, instead of temporary curing. That method is used overseas. However, there are problems of having to newly install equipment and problems of energy required for constant heating. In addition, it is heated for baking the paint after application, but the baking temperature is higher than the temperature at the time of hot application, so it must be designed so that the curing reaction occurs at this baking temperature. There is also the above problem. Furthermore, since an adhesive having a high viscosity at room temperature needs to be heated during production and mixing, there is also a problem that the reaction proceeds and storage stability is deteriorated.

  When a two-component mixed instantaneous curing type adhesive is used, it cures immediately after application, but there is a problem of capital investment that a mixing device such as a static mixer must be newly installed. If a mixing device is not used, a process of applying different liquids for each surface to be adhered and attaching them will be adopted, but such a construction method is not practical.

  One-component moisture-curing adhesives are often used in other industries such as construction, but there is no reality that does not require special equipment at a curing speed that catches up with the automotive industry's line speed and does not have storage stability problems. . Although there is an idea that the hardener is microencapsulated into a one-pack type, there is still no convenient microcapsule that is stable during production mixing and that breaks or melts immediately after application and cures.

  UV curable adhesives are solvent-free and are usually oligomers with (meth) acrylic groups in the main chain of rubber or (meth) acrylic (acrylic or methacryl is referred to as (meth) acrylic). , (Meth) acrylic monomer and photo radical initiator, and does not contain filler. The ultraviolet irradiation device is also simple, and recently, more energy-saving types such as LEDs are commercially available. Since it does not require heating, it is energy-saving, is cured for a short time, and is used for bonding glasses such as camera lenses.

  However, if an ultraviolet curable adhesive is to be used as a body sealer, the raw material price is very high compared to the currently used body sealer, and there are the following technical problems.

  In general, an adherend of a body sealer is a steel plate that is opaque to light, unlike a transparent glass.

  Further, the thickness of the adhesive layer in the case of glass is about 0.1 mm, but in the case of a body sealer, it is extremely thick as 1 to 5 mm. Therefore, the light hardly reaches the whole, and the bottom may remain uncured. In that case, there is a possibility that the lion of the wharf will pop out when crushed.

  Furthermore, in the case of radical polymerization of an acrylic monomer by a photoinitiator, oxygen in the air traps and stabilizes radicals. Therefore, depending on the prescription, the surface portion exposed to the air other than the adhesive surface is inhibited from being cured by oxygen in the air, and the surface may not be cured and may become sticky. As a technique that does not suffer from the inhibition of oxygen in the air, there is an ultraviolet curable type that generates a strong acid by light and performs cationic polymerization. This has the advantage that once the light is received, the reaction proceeds as it is. However, in order to use a large amount as a body sealer, it is necessary to add an inorganic filler for economic reasons, and the reaction may be hindered by moisture brought in by the filler. In addition, the photocation initiator is expensive, and it is antimony-based or contains fluorine or phosphorus. Therefore, many of them contain environmental problems in recent years, so it is difficult to adopt them practically.

  The existing body sealer is applied with a thickness of 1 to 5 mm, and then the paint is overcoated after temporary curing by heating at about 140 ° C. For smooth finish, it must have low viscosity, good coating workability, and must be cured in a relatively low temperature range. The physical properties after curing are adhesiveness to ED (electrodeposition) paint and top coating It is required that the paintability and adhesion with respect to the resin be good and that sufficient elongation followability is required. Therefore, at present, vinyl chloride resins, their copolymer resins, acrylic resins, methacrylic resins, or acrylic-methacrylic copolymer resin powders and organosol thermoplastic resins composed of plasticizers of those resins are used. Yes. If a normal UV curable adhesive is used as a body sealer, in addition to economic problems, the surface is uncured and sticky and the paint cannot be applied, or the interior may be cured by light depending on the thickness. Problems such as bad occur.

  Therefore, the present invention provides the above-mentioned energy-saving, which is desired to be improved with respect to the existing body sealer by imparting the performance of pre-curing or curing by irradiating energy rays such as ultraviolet rays, visible rays, and electron beams after coating. It is an object of the present invention to provide a body sealer that can be blended in a simple and economical manner capable of saving processes and preventing deformation, cracking, dropping off, or distortion in the middle of the line.

  The present inventors have developed an ultraviolet curable adhesive so as to satisfy the properties such as adhesion force and tensile physical properties to various adherends of automobile body sealers, adhesion to ED paint, and adhesion of top coating. This has led to the present invention.

  That is, the body sealer of the present invention comprises a monomer or an oligomer and contains a polymerizable component that is polymerized by ultraviolet rays, visible rays, or electron beams, and a thermoplastic resin component as essential components.

  The monomer or oligomer that is a polymerizable component that is polymerized by energy rays such as ultraviolet rays, visible rays, and electron beams may have a unsaturated bond such as a vinyl group, an allyl group, or an aryl group. A highly polymerizable acrylic or methacrylic one is preferred.

  There are several selection criteria for polymerizable components. For example, it has low functional skin irritation, low cost, and has a multifunctional group that is not easily inhibited by oxygen in the air. Depending on the combination with thermoplastic resin, which is another essential component, compatibility criteria such as hydrophobicity or hydrophilicity, reactivity, storage stability, glass transition temperature related to elongation, cold bending, etc. are also selected criteria It becomes. Furthermore, the types of adherends such as steel plates, galvanized steel plates, aluminum plates, and ED coated steel plates, and the adhesiveness such as oil level fixation are also selection criteria. In order to improve the adhesion to the adherend, it is effective to add a monomer or oligomer having a metal salt structure such as zinc, aluminum or magnesium. The polymerizable component is selected so as to satisfy one or more of these selection criteria.

  When light irradiation was performed after application of an ultraviolet curable adhesive as a body sealer, problems were that curing did not proceed to the inside and that there were few economical fillers. In order to solve these problems, it is effective to use powders of inorganic materials such as feldspar, glass balloons, glass beads, and hydrotalcite as fillers. This is because these inorganic materials have a refractive index of about 1.5, which is the refractive index of thermoplastic resins, rubbers, epoxy resins and plasticizers used for adhesives, and are transparent powders. Of course, it is possible to use an economical calcium carbonate which is generally used in view of the situation. In addition, since light with a longer wavelength tends to penetrate deeper into the substance, it is realistic as a body sealer by providing internal curability by using a radical initiator by visible light in addition to a radical initiator by ultraviolet light. The solution to the level became possible. Even if the temperature of the heating step in the subsequent step is not so high, a radical generator due to heat may be added in order to allow the polymerization of the monomer or oligomer to proceed in the heating step in order to compensate for curing by light irradiation. Good.

  The blending ratio of the polymerizable component monomer or oligomer varies depending on the purpose, component or application of the body sealer, but 0.5 to 50 parts by weight is appropriate for the total 100 parts by weight of the whole body sealer. is there. If the proportion of the polymerizable component is less than this, it will be difficult to obtain sufficient strength, internal curing and adhesive effect until the next heat curing process in the pre-cured state, and the heating process will enter later when cured by light irradiation. In such a case, thermal deformation or shrinkage due to progress of curing by another mechanism occurs. On the other hand, if the proportion of the polymerizable component is higher than this, not only will it become economical, but the properties after curing will be less stretched and elastic compared to existing body sealers, and it will become brittle. As unsuitable. The blending ratio of the polymerizable component is preferably 5 to 30 parts by weight if the main purpose is temporary curing, and 15 to 40 parts if it is expected to cure without causing shrinkage due to heating in the subsequent step. preferable.

After applying the body sealer of the present invention and curing with energy rays using an ultraviolet ray irradiation device or an electron beam irradiation device, it is observed whether the improvement effect expected in performance and physical properties such as whether the surface state can be applied with a paint finish is obtained. Furthermore, it is confirmed whether there is no problem after following the heat curing conditions received in the subsequent process. An energy-saving LED with less heat generation is recommended as an ultraviolet irradiation device. However, in the embodiments of the present invention, a handy type high-pressure mercury lamp HLR100T-2 (Sen Special Light Source Co., Ltd.) is used, and the wavelength is around 365 nm. And an integrated energy of 4500 mj / cm ² (180 seconds) with an illuminance of 25 mW / cm ² (distance of about 10 cm). Then, after applying the finish paint, heating was performed at 140 ° C. for 20 minutes for curing, and then physical properties and appearance were evaluated.

  Since the body sealer of the present invention has been imparted with curing or provisional curability by energy rays such as ultraviolet rays, visible rays, and electron beams, a heating step called preheating can be omitted, saving energy and time. Finish coating is possible, and it will be possible to provide adhesives with excellent cost performance (cost-effectiveness).

  The polymerizable components used in the examples were isobornyl acrylate as an acrylic acid derivative as a monomer, 2-ethylhexyl methacrylate as a methacrylic acid derivative, UN1255 as an acrylic acid derivative as an oligomer (bifunctional of Negami Industrial Co., Ltd.) Non-yellowing urethane acrylate oligomer), TEA1000 (bifunctional polybutadiene rubber main chain acrylate oligomer of Nippon Soda Co., Ltd.), and TE2000 (bifunctional polybutadiene rubber main chain methacrylate oligomer of Nippon Soda Co., Ltd.) were used as methacrylic acid derivatives. . Zinc dimethacrylate was used as an acrylic acid derivative containing a metal salt structure.

  Irgacure 184 (product of Nippon Ciba Geigy Co., Ltd.) and Irgacure 819 (product of Nippon Ciba Geigy Co., Ltd., visible light initiator) were used as photo radical initiators.

  Among the thermoplastic resins used in Examples or Comparative Examples, P440 and P500 (product of Vitec Co., Ltd.) as vinyl chloride resin and copolymer resins thereof, and Dainal LP3109 (as a powder of acrylic, methacryl and copolymer resins thereof) Mitsubishi Rayon Co., Ltd. core-shell type acrylic powder) was used.

  As the plasticizer, diisononyl phthalate (DIAIP product DINP) was used.

  Minex 7 (Shiroishi Kogyo Co., Ltd. product), Glass Bubbles S22 (Sumitomo 3M Co., Ltd. glass balloon), GB-G-P20PM (Potters Ballodini Co., Ltd.) Glass beads), DHT4A (hydrotalcite powder, a product of Kyowa Chemical Industry Co., Ltd.) are used, and some of them are replaced with white glaze CCR (synthetic calcium carbonate of Shiroishi Kogyo Co., Ltd.) to prevent abnormal foaming due to moisture. Therefore, it was used after sufficiently drying. In some of the comparative examples, heavy calcium carbonate (product Whiten P-30 manufactured by Toyo Fine Chemical Co., Ltd.) was used instead of Minex 7.

In Examples and Comparative Examples, the composition was mixed with three rolls according to each formulation, and then defoamed under reduced pressure while stirring to prepare an adhesive. The adhesive is 25 mm wide, 100 mm long, and 1 mm thick cold rolled steel sheet (ED coated steel sheet for body sealers using thermoplastic resin) with a thickness of 2 mm, and then the above-mentioned handy type high pressure mercury lamp Using HLR100T-2 (product of Sen Special Light Source Co., Ltd.), irradiating with an illuminance of 25 mW / cm ² at a wavelength of 365 nm (distance of about 10 cm) and an accumulated energy of 4500 mj / cm ² (180 seconds) to confirm the cured state Went.

  The cured state was determined based on whether or not the finish sealer using a thermoplastic resin could be applied without any problem.

  Another set of the same specimens was prepared, and after light irradiation under the above conditions, it was cured by heating at 140 ° C. for 20 minutes, and a comparative observation was made to see if there were any major problems in the final state such as hardness. .

  In another test, an adhesive with a thickness of 2 mm in the form of a 25 mm wide strip extending from one end in the longitudinal direction of the previous metal plate (width 25 mm, length 100 mm, thickness 1 mm) over the entire width of the metal plate. After coating, a glass plate having the same size as the metal plate and a thickness of 5 mm is superimposed on the adhesive symmetrically with the metal plate, irradiated with light through the glass under the above conditions, and then each of the above temperatures. It was cured by heating for 20 minutes under the conditions (140 ° C for an adhesive formulated with a thermoplastic resin, 160 ° C for an adhesive formulated with rubber, and 180 ° C for an adhesive formulated with epoxy).

  As described above, a test piece obtained by hardening and bonding a glass plate and a steel plate by light irradiation and heating was applied to a tensile tester to perform a shear tensile test. The evaluation in the adhesive breakage state is that the one that breaks at the center of the cured adhesive and the one that breaks near the glass interface (the test body used glass on one side of the adherend as a model of light irradiation) Since the body sealer of the present invention was not used for glass, it was evaluated in this way.), Δ that breaks in the state where the hardened adhesive is somewhat adhered to the metal surface, and peeled off at the interface between the hardened adhesive and the steel plate The thing was determined as x. Also, the tensile strength in the tensile test is 3 MPa or more, ◎ less than 3, 1 MPa or more ○, less than 0.5 MPa or more Δ, less than 0.5 MPa ×, Table 1 shows the results and Table 2 shows the results of the comparative examples.

The blending ratio of each component was blended as in Examples 1 to 14 below.
Example 1
20 parts by weight of TEA1000 as an oligomer, 0.4 parts by weight of Irgacure 184 as a photoinitiator, 0.2 parts by weight of Irgacure 819, 20 parts by weight of P500 as a vinyl chloride component, 45 parts by weight of Minex 7 as a filler, 15 parts by weight of DINP as a plasticizer was blended and kneaded to obtain an adhesive for body sealer use.

(Example 2)
In Example 1, the oligomer was reduced to 5 parts by weight and the plasticizer was increased to 30 parts by weight.

(Example 3)
In Example 1, the oligomer was increased to 40 parts by weight, the vinyl chloride component was reduced to 10 parts by weight, and the plasticizer was reduced to 5 parts by weight.

Example 4
In Example 1, the vinyl chloride component was changed to P440.

(Example 5)
In Example 1, the filler was changed from 45 parts by weight for Minex 7 in Example 1 to 30 parts by weight for Minex 7 and 15 parts by weight for the glass balloon.

(Example 6)
In Example 1, the filler was changed to glass beads.

(Example 7)
In Example 1, the filler was changed to hydrotalcite.

(Example 8)
In Example 1, the filler was changed from 45 parts by weight for Minex 7 in Example 1 to 35 parts by weight for Minex 7 and 10 parts by weight for white gloss CCR.

Example 9
In Example 1, the oligomer was changed to 2-ethylhexyl methacrylate which is a methacrylic monomer.

(Example 10)
In Example 1, the oligomer was changed to isobornyl acrylate which is an acrylic monomer.
(Example 11)
In Example 1, the oligomer was changed to UN1255 which is a main chain acrylic oligomer.

Example 12
In Example 1, the oligomer was changed to TE2000 which is a methacrylic oligomer.

(Example 13)
In Example 1, only 5 parts by weight of 20 parts by weight of oligomer was changed to zinc dimethacrylate.

(Example 14)
In Example 1, the vinyl chloride component was changed to Dianal LP3109, which is a powder of acrylic, methacrylic and copolymer resins thereof.

  In addition to the examples, conventionally used comparative examples relating to prescriptions and ranges of addition amounts were also evaluated in the same manner, and the evaluation results are shown in Table 2 below.

The blending ratio of each component of the comparative example was blended as in the following comparative examples 1-6.
(Comparative Example 1)
25 parts by weight of P500 as a vinyl chloride component, 45 parts by weight of Minex 7 as a filler, and 30 parts by weight of DINP as a plasticizer were blended and kneaded to obtain an adhesive.
This is close to the composition of Example 1 excluding the oligomer component.

(Comparative Example 2)
0.5 parts by weight of TEA1000 as an oligomer, 0.2 parts by weight of Irgacure 184 as a photoinitiator, 0.1 parts by weight of Irgacure 819, 25 parts by weight of P500 as a vinyl chloride component, 45 weights of Minex 7 as a filler And 30 parts by weight of DINP as a plasticizer were mixed and kneaded to obtain an adhesive. This is the same as in Example 1, but the components are the same, but the oligomer components are extremely reduced.

(Comparative Example 3)
60 parts by weight of TEA1000 as an oligomer, 0.4 parts by weight of Irgacure 184 as a photoinitiator, 0.2 parts by weight of Irgacure 819, 5 parts by weight of P500 as a vinyl chloride component, 30 parts by weight of Minex 7 as a filler, 5 parts by weight of DINP as a plasticizer was blended and kneaded to obtain an adhesive. Compared with that of Example 1, the components are the same, but the oligomer components are extremely increased.

(Comparative Example 4)
In Example 1, the filler was changed from Minex 7 to heavy calcium carbonate.

(Comparative Example 5)
In Example 1, the acrylic oligomer was changed to a DAP monomer having a functional group and an allyl group with a slow radical reaction rate (product diallyl phthalate from Daiso Corporation).

(Comparative Example 6)
In Comparative Example 1, the vinyl chloride component was changed to Dianal LP3109, which is an acrylic resin powder. This is close to that in Example 14 where the oligomer was omitted.

  In Examples and Comparative Examples, photocurability was determined by paintability. That is, after being applied to an electrodeposited steel sheet, a solvent-based automotive intermediate coating was applied to a product that had been irradiated with ultraviolet rays under predetermined conditions, left at room temperature for 5 minutes, and then baked at 140 ° C. for 20 minutes to determine the appearance. In all of the examples, there was no problem, and in the comparative example, except for Comparative Example 3, which had excessive oligomers, it was not cured and could not be coated, or the surface and the interior were poorly cured and the finish of the coating was poor.

  The tensile test after thermosetting was performed by applying ultraviolet rays from the glass surface side after applying each adhesive on the electrodeposition coated steel sheet and cold rolled steel sheet as described above, and further at each temperature condition. After heat-curing, it was carried out with an autograph (product of Shimadzu Corporation) at a pulling speed of 50 mm / min. When the breaking strength was evaluated, in both Examples and Comparative Examples, ◎ having a breaking strength of 3 MPa or more, ◯ having a breaking strength of less than 3 and 1 MPa or more were halved, and Δ or less being 0.5 MPa or more. There was no x that was less than 0.5 MPa.

  In the examples, the required breaking strength and the breaking position were no problem. In the comparative example, there was no problem in the breaking strength, but the oligomer was excessive (Comparative Example 3), the fractured state was poor, and the fracture was caused with the adhesive cured body somewhat adhered to the steel plate surface. This is considered to be caused by the fact that curing by ultraviolet curing is too strong, and movement between substances that undergo a curing reaction during heating cannot be sufficiently performed.

  Based on the above result, it turns out that the body sealer of an Example can provide the performance of temporary hardening and hardening by light irradiation.

  This is characterized by containing a polymerizable component by energy rays such as ultraviolet rays, visible rays, and electron beams in an appropriate range in an adhesive, and a thermoplastic resin, rubber or thermosetting resin as essential components. This means that the development of the body sealer has been completed.

The present invention is not limited to the above embodiments.
Usually, the monomer or oligomer is an acrylic acid derivative or a methacrylic acid derivative, but their molecular structure is a vinyl chloride resin, an acrylic resin, rubber or an epoxy resin, and these have an acrylic group or a methacrylic group. Even what is added can be implemented.

Claims (7)

  An automotive body sealer comprising a polymerizable component comprising a monomer or oligomer and polymerized by ultraviolet light, visible light or electron beam, and a thermoplastic resin component.   The automobile body sealer according to claim 1, wherein the polymerizable component is an acrylic acid derivative or a methacrylic acid derivative.   The automobile body sealer according to claim 2, wherein at least part of the acrylic acid derivative or methacrylic acid derivative is a metal salt.   The thermoplastic resin is a resin powder selected from the group consisting of vinyl chloride, a copolymer resin of vinyl chloride and others, an acrylic resin, a methacrylic resin, and an acrylic-methacrylic copolymer resin, and a plastic of the resin. The automobile body sealer according to any one of claims 1 to 3, wherein the body sealer is an organosol resin composed of an agent.   The automobile body sealer according to any one of claims 1 to 4, wherein a blending ratio of the polymerizable component is 0.5 to 50 parts by weight with respect to a total of 100 parts by weight of the whole body sealer. Use powder that is transparent to ultraviolet or visible light as a filler,
The automobile body sealer according to any one of claims 1 to 5, which contains both a radical initiator by ultraviolet rays and a radical initiator by visible light to impart internal curability.   The automobile body sealer according to claim 6, wherein the powder is a powder of an inorganic material selected from the group consisting of feldspar, glass balloon, glass beads, and hydrotalcite.