JPH02233747A - Adhesive composition for hemming part of automotive body - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive composition, excellent in flexibility, bonding durability, rust preventing properties, etc., and useful for hemming parts of automotive bodies by blending a vinyl chloride-based polymer with a plasticizer, epoxy resin, latent amine adduct type curing agent, latent curing agent and filler at a specific ratio. CONSTITUTION:An adhesive composition, consisting of (A) 100pts.wt. vinyl chloride-based polymer with (B) 20-100pts.wt., preferably 30-80pts.wt. plasticizer (e.g. di-2-ethylhexyl phthalate), (C) 20-300pts.wt., preferably 30-200pts.wt. epoxy resin, (D) 2-50pts.wt., preferably 3-40pts.wt. latent amine adduct type curing agent, (E) 3-60pts.wt., preferably 4-50pts.wt. latent curing agent (e.g. dicyandiamide) and (F) 30-200pts.wt. filler and obtained by preferably finely dispersing the total amount of the components (D), (E) and (F) in 20wt.% component (B) and the total amount of the component (C), then kneading and blending the resultant dispersion with a plastisol consisting of the total amount of the component (A) and the residual component (B).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an adhesive composition suitable for filling hemming parts of automobile bodies.

[Problems to be solved by conventional techniques and inventions] In recent years, there has been a great social need to improve the durability of automobiles and extend the lifespan of automobiles from the perspective of resource conservation. An important point in extending the lifespan of a car body is to protect it from rust. In particular, there are parts of the car body that are difficult to apply anti-rust treatment to due to its structure, such as door hemmings, hood inner end hemmings, and rocker panels.
These parts have a bag structure, so if water or moisture from rainwater or other sources enters, it tends to accumulate, causing rust and shortening the lifespan of the car body.

Conventionally, paste-like epoxy resin adhesives have been mainly used for these parts. That is, as shown in FIG. 1, after applying adhesive 3 to the green part of the temporary exterior 1 and aligning the edge of the interior panel 2 with this, the edge of the exterior panel 1 is folded back, press-formed, and bent. The portion 1a is formed to form a hemming structure. Panels with this hemmed structure are
It is assembled by spot welding for temporary fixing, and then subjected to chemical conversion treatments such as degreasing, cleaning, and acid treatment along with the entire car body, and then subjected to the electrodeposition painting process, where the adhesive is cured and fixed in a paint baking oven during this process. . However, with paste-like epoxy resin adhesives, the adhesive tends to fall off or scatter, and the processing liquid is contaminated during the degreasing, cleaning, acid treatment, etc. Additionally, spot welding for temporary fixing tends to leave dents, which is unfavorable for the appearance of the car body. Furthermore, after the epoxy resin adhesive is baked and hardened in the electrodeposition coating process, it is highly rigid and dynamic stress such as vibrations during the car body assembly process or while driving causes the ends of the hardened epoxy resin adhesive to become electrodeposited. There is a problem that the coating peels off from the edge 4a or cracks form, and there is a disadvantage that water and moisture enter from there and rust occurs. Furthermore, epoxy resin adhesives are expensive and have economical problems. Therefore, recently, hemming adhesives (1) can be used to temporarily fix panels with a hemmed structure formed by coating and molding by means other than temporary fixing spot welding, such as short-time low-temperature preheating, and (2) are used in the next process. There is no falling off, scattering, or contamination of the processing solution during degreasing, acid treatment, etc.
3) It has sufficient adhesion and flexibility after baking hardening in the electrodeposition coating process, and (4) It satisfies all of the following: (1) For temporary fixing properties, it is highly desirable to have relatively high adhesive strength when cured by low-temperature preheating. In addition to these requirements, appropriate viscosity for application work, storage stability,
It is also essential to satisfy the adhesion properties to oil-surface steel plates. As a material for a hemming adhesive that satisfies the above requirements, a composition in which vinyl chloride plastisol is blended with an epoxy resin and its curing agent has been proposed. For example, JP-A-55-48272 and JP-A-62-146973. The former is a reaction product (solid) of vinyl chloride polymer with carboxyl group/plasticizer/liquid epoxy resin/aliphatic polyamine and polycarboxylic acid or anhydride.
The latter is a composition consisting of a vinyl chloride polymer/synthetic rubber/plasticizer/dialkyl peroxide/liquid epoxy resin/specific polycarboxylic acid hydrazide (curing agent)/filler. The composition is as follows. However, the former does not enable a hardened state for temporary temporary fixing, and the latter does not allow for hoods, roofs, etc. of automobile bodies.
This mastic adhesive is used in the door assembly process to join the outer panel with the frame-shaped inner panel that is reinforced from the inside, and is used to dampen vibrations and improve rigidity. Discharge coating workability, adhesion to rust-preventing oil-surfaced steel plates, shower resistance during the chemical conversion process, and vibration during transport in an uncured state until the mastic adhesive is transferred to the electrodeposition coating baking process where it is cured. It is a product with improved followability that allows it to be joined when it is attached, but it is not something that can be temporarily fastened without spot welding, and it is far from meeting all of the above requirements, such as having sufficient adhesive strength at high temperatures. In order to solve the above problems as an adhesive for hemming, the present inventors focused on the fact that vinyl chloride polymer plastisol gels when heated at low temperature for a short time, and developed a vinyl chloride polymer blastisol adhesive 'liq. As a result of intensive research into compositions, we found that the above problems can be solved by blending vinyl chloride polymer powder/plasticizer/epoxy resin/latent amine adduct type curing agent/latent curing agent/filler in a specific ratio. Heading,
We have now completed the present invention. [Means for Solving the Problems] The present invention comprises (A) 100 parts by weight of a vinyl chloride polymer, (
B> 20-100 parts by weight of plasticizer, + (C) 20-300 parts by weight of epoxy resin, (D) 2-50 parts by weight of latent amine adduct type curing agent, (!) 3-6 parts by weight of latent curing agent
The present invention provides an adhesive composition characterized in that it contains 0 parts by weight of filler (F) and 30-200 parts by weight of filler (F). The vinyl chloride polymer (A) of the present invention may be one normally used for plastisol, and may be one produced by emulsion polymerization, suspension polymerization, solution polymerization, etc. of vinyl chloride alone or with other copolymerizable monomers. You may also use The plasticizer (B), which is a component of the adhesive of the present invention, is not particularly limited as long as it can be used for vinyl chloride polymers, but examples include di-n-butyl phthalate and di-n-phthalate. Phthalic acid plasticizers such as octyl, di-2-ethylhexyl phthalate (DOP), diisooctyl phthalate, octyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl isophthalate, di-2-ethylhexyl adipate (D.O.
A) Fatty acid ester plasticizers such as di-n-decyl adipate, diisodecyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, triptyl phosphate, tri-2-ethylhexyl phosphate , phosphate ester plasticizers such as 2-ethylhexyldiphenyl phosphate and tricresyl phosphate, epoxidized soybean oil, and epoxy plasticizers such as epoxidized tall oil fatty acid-2-ethylhexyl. Use seeds or a mixture of two or more.

The amount of plasticizer used is 20 to 100 parts by weight, preferably 30 to 80 parts by weight, per 100 parts by weight of the vinyl chloride polymer.

If the amount of plasticizer is less than 20 parts by weight, the adhesive after heat curing will be hard and not flexible, and if it exceeds 100 parts by weight, the cohesive force of the adhesive after heat curing will be low and the adhesive force will be small. Therefore, it is not suitable as the adhesive composition of the present invention.

The epoxy resin (C) of the present invention has an average of 2
An epoxy resin having more than one epoxy group is used. Examples of such epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, novolac epoxy resins, polyfunctional phenol epoxy resins, and various halogenated epoxy resins. In addition, diglycidyl ether compounds obtained by the reaction of resorcinol and epihalohydrin,
Glycidyl ester type epoxy resins, polyglycol type epoxy resins, cycloaliphatic epoxy resins, hydantoin type epoxy resins, glycidylamine type epoxy resins, etc. can also be used.

Epoxy resins can be used alone or in combination of two or more.

The amount of epoxy resin used is 20 to 300 parts by weight, preferably 30 to 2 parts by weight, per 100 parts by weight of the vinyl chloride polymer.
00 parts by weight. If it is less than 20 parts by weight, the adhesive force will be insufficient, especially at high temperatures, and if it exceeds 300 parts by weight, the adhesive will become too hard after being cured by heat, and its flexibility will be impaired.

Especially when high adhesive strength is desired at high temperatures,
The amount of epoxy resin used is preferably 80 parts by weight or more per 100 parts by weight of the vinyl chloride polymer.

The (D) latent amine adduct type curing agent used in the present invention is an amine compound that is generally known to react with epoxy resins to form adducts. For example, Amicure PN manufactured by Ajinomoto Co., Ltd. -2 3, Amicure MY-24, etc.

The amount of the latent amine adduct type curing agent used is 2 to 50 parts by weight, preferably 3 to 40 parts by weight, per 100 parts by weight of the vinyl chloride polymer. If it is less than the double leg portion, temporary adhesive strength will not be sufficiently exerted. Moreover, if it exceeds 50 parts by weight, the adhesive after heat curing becomes hard and brittle.

Next, as the curing agent (E) used in the present invention, one that is most commonly used as a curing agent for epoxy resins is used. Examples include guanidine derivatives, triazine derivatives, 4,4'-diaminodiphenylsulfone, acid hydrazide compounds, imidazole compounds, N,N'-dialkyl urea derivatives, and N,N'-dialkylthiourea derivatives. The amount used is 3 to 60 parts by weight, preferably 4 to 60 parts by weight, per 100 parts by weight of the vinyl chloride polymer.
It is 50 parts by weight. If it is less than 3 parts by weight, curing is insufficient and no adhesive strength is developed, and if it exceeds 60 parts by weight, the adhesive after heat curing becomes hard and brittle.

The filler (F) used in the present invention includes calcium carbonate, barium carbonate, magnesium carbonate, calcium sulfate,
Examples include carbonates or sulfates of alkaline earth metals such as barium sulfate or magnesium sulfate, silica, clay, titanium oxide, aluminum oxide, powder, and the like. The amount used is 30 to 20 parts by weight per 100 parts by weight of the vinyl chloride polymer.
This is 0ju Satobe. If it is less than 30 parts by weight, the cohesive force of the heat-cured adhesive will be insufficient, and if it exceeds 200 parts by weight, the heat-cured adhesive will become too hard and its flexibility will be impaired.

Furthermore, in addition to the above-mentioned components, various other additives such as stabilizers, fenders, thixotropic agents, etc. can be added to the composition of the present invention. Stabilizers include metal soaps (e.g. calcium stearate, aluminum stearate, etc.), inorganic acid salts (e.g. dibasic phosphite,
dibasic sulfate, etc.) and organometallic compounds (e.g., dibutyltin dilaurate, dibutyltin malate, etc.). As anti-rust pigments, chromates (e.g.
Strontium chromate, barium chromate), basic lead sulfate, lead cyanamide, etc. Examples of the thixotropic agent include fine silica, organic bentonite, and ultrafine calcium carbonate. Further, when the adhesive composition contains water, it is also possible to add and mix a relatively small amount of powder such as calcium oxide, magnesium oxide, silicon oxide, etc. as a water adsorbent. Furthermore, coloring agents such as carbon plaque and red iron can be optionally added. The adhesive composition according to the present invention can be obtained by kneading the above-mentioned components using a kneading machine represented by a three-roll mixer, a twenty-one goo mixer, a paddle mixer, a planetary mixer, a disperser mixer, etc., by conventional means.

In particular, the total amount of the latent amine adduct type curing agent, the latent hardening agent, and the filler are finely dispersed in 20% by weight of the plasticizer used and the total amount of the epoxy resin, and then the total amount of the vinyl chloride polymer and the remaining plasticizer are dispersed. The composition of the present invention, which is prepared by kneading and blending into a vinyl chloride polymer plastisol consisting of an agent, further solves the above-mentioned problems and is more effective for hemming automobile bodies. This is because the latent amine adduct-type hardener, latent hardener, and filler, which are mainly solid powders, are differentiated into effective amounts of plasticizer and epoxy resin, and then these are compatibilized into vinyl chloride-based polymer plastisol. This is thought to be due to penetration into the vinyl chloride polymer particles.

In this case, when a stabilizer or antirust pigment is blended, it is preferable to finely disperse it together with the latent amine adduct type curing agent, latent curing agent, and filler. Three rolls for fine dispersion,
It is preferable to use a kneader mixer or a disk bar mixer.

The composition of the present invention is particularly excellent as an adhesive for the automobile industry, particularly for hemming automobile bodies, but it can also be applied to various industrial uses as a sealant, paint, etc. in addition to being used as an adhesive.

〔Effect of the invention〕

The composition of the present invention can (1) exhibit sufficient adhesive strength and temporarily fix panels with a hemmed structure by coating and molding without requiring spot welding for temporary fixing, especially with short-time low-temperature preheating; , (2) There is no falling off, scattering, or contamination of the processing solution during the next process of degreasing, cleaning, acid treatment, etc., and (3) after baking and hardening, it has sufficient adhesive strength and flexibility, especially not only at room temperature but also at high temperatures. and (4) sufficient long-term adhesive durability and rust prevention properties, so it is suitable as an adhesive for hemming automobile bodies.

(Examples) Next, the present invention will be explained by examples, but the present invention is not limited to these examples.

The test and evaluation method was as follows.

(1) Storage stability of viscosity The viscosity was measured using a capillary extrusion type viscometer at 35°C and a shear rate of 6.
The value was taken as the value at 2 sec-'. Storage stability shows that the viscosity change rate is 30% after holding the adhesive composition at 40°C for 7 days.
If it falls within this range, mark it as ○, and if it exceeds 30%, mark it as ×.
And so.

(2) Adhesion Using an oil-faced steel plate (spc-o'iA plate) coated with anti-corrosion oil, heat cure at 150°C for 10 minutes and at 70°C for 20 minutes to determine shear adhesion and peeling. Adhesive strength is J
It was measured at 23°C in accordance with ISκ6850 and JIS K6854. The adhesive strength when cured at 150°C-tO was used as a measure of temporary fixing property. Also, the adhesive strength at high temperatures is 1
Regarding the cured product cured at 70'C for 20 minutes, 1
The shear adhesive strength was measured at 50°C. (3) After applying a flexible adhesive to an oil surface steel plate in a shape of 150 x 25 x 1 mm, heat and harden it at 170°C for 20 minutes, and bend the steel plate at an angle of 90° using a 1-inch diameter mandrel at room temperature. In this case, the case where the cured adhesive layer did not crack was rated as ◯, the case with slight cracking was △, and the case with cracking was rated as ×.

(4) Adhesive durability The heat-cured test piece of (2) above for 20 minutes at 170°C was
゛C, 23℃ after 30 days of storage under 95% Rl+
The adhesive strength was measured, and the case where the strength was 80% or more of the initial strength was rated as ○, and the case where it was less than 80% was rated as ×.

(5) Rust prevention After applying the adhesive of the present invention to the lower part of the exterior plate 1 at the hemming part of the automobile body shown in Figure 1.2 using a coating gun,
The temporary interior 2 was pressed against it, and the lower end of the temporary exterior 1 was bent and caulked. Thereafter, this was heated at 150° C. for 10 minutes to heat and cure the adhesive, and then the protruding portion from the edge 2a toward the interior panel was removed and electrocoated. Baking conditions are 1
At 70°C. It was set as 20 minutes. The hemming model thus obtained was subjected to a rust prevention test. Rust resistance is 5% at 50°C
One cycle was immersed in NaC E aqueous solution for 4 hours, air-dried at 80°C for 2 hours, and left at room temperature for 2 hours. Cases were marked as ○, and severe cases were marked as ×.

Examples 1 to 4 and Comparative Example 1 Predetermined parts by weight of the raw materials shown in Table 1 were added, kneaded, and defoamed to obtain adhesive compositions. In this case, the latent amine adduct type curing agent, latent curing agent, filler, stabilizer, rust preventive pigment, and plasticizer used are blended and finely dispersed with 20% by weight and epoxy resin using a three-roller. Component (1) was prepared, and a vinyl chloride plastisol consisting of a vinyl chloride polymer and a residual plasticizer was prepared in a planetary mixer to obtain component (II). Next, component (1) was mixed and kneaded in a plastic mixer containing component (II), and then a thixotropic agent was mixed and kneaded, followed by defoaming under reduced pressure. The results of various tests are shown in Table 2.

As shown in Table 2, the adhesive composition of the present invention shown in the Examples satisfies the characteristics required for a hemming adhesive,
In particular, it has been shown that it has high adhesive strength even when cured by low-temperature preheating, and also has high adhesive strength at high temperatures.

(Hereafter, margin)

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the structure of an automobile body hemming part using the adhesive of the present invention, and FIG. 2 is a perspective view thereof. 1... Exterior plate 1a... Bent part 2...
・Interior board 2a...Edge 3...Adhesive

Claims (1)

[Claims] (1) (A) 100 parts by weight of vinyl chloride polymer, (B)
20-100 parts by weight of plasticizer, (C) epoxy resin 20-
300 parts by weight, (D) latent amine adduct type curing agent 2
-50 parts by weight, (E) 3-60 parts by weight of latent curing agent, (
F) An adhesive composition for a hemming part of an automobile body, characterized in that it contains 30 to 200 parts by weight of a filler.