JPH08120141A - Polyvinyl chloride-plastisol composition - Google Patents

Abstract

PURPOSE: To prevent swelling and generation of pin holes even in case when a gap of a hemming part is large. CONSTITUTION: This polyvinyl chloride-based plastisol composition comprises a polyvinyl chloride-based resin consisting of a mixture of a polyvinyl chloride single polymer with a copolymer and a plasticizer as essential components. The viscosity (v) of the composition measured by a BH-type viscometer using No.7 rotor at 20 deg.C is expressed by the formula, 170 (P.s)<=(v)<230(Pa.s). The time (t) of the composition when stoved at 140±2 deg.C until a period measured by a pendulum viscoelastometer becomes 0.60 (s) is expressed by the formula, 14<=(t)<=20 minutes. The plastisol can prevent sags during coatings and is excellent in a leveling propert. As a gelling speed during stoving is appropriate, a swollen air can be discharged. Thus swellings and pin holes can be prevented because the gelling takes place after holes made by discharges of air are closed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl chloride plastisol composition (hereinafter referred to as a PVC sol composition) which is useful as a sealing material used for a steel plate connecting portion such as a hemming portion of an automobile.

[0002]

2. Description of the Related Art The joints and joints of steel sheets, such as the hemming portion of an automobile body, are difficult to cover with ordinary paint, and moreover, water and dust easily enter the boundary and rust easily occurs. is there. Therefore, in such a portion, for example, Japanese Patent Laid-Open Nos. 61-23676 and 62
As disclosed in JP-A-84175, JP-B-3-31754, etc., a sealing material composed of a PVC sol composition is applied and filled, and an intermediate coating film and a top coating film are further formed on the surface thereof. ing.

This PVC sol composition is based on a vinyl chloride resin made of a homopolymer of vinyl chloride or a copolymer of vinyl chloride and vinyl acetate, and a plasticizer such as DOP as a base material. Adhesion-imparting agent, filler such as calcium carbonate, and stabilizer such as metallic soap are included. Further, in order to impart anti-sagging performance, a rheology control agent such as calcium carbonate surface-treated with fatty acid or ultrafine silica powder is generally used.

As the PVC sol composition for sealing, there are known one having flowability and one having little flowability depending on the application conditions. A material having a flow property has an advantage that it easily penetrates into the gap between the steel plates, but has a problem in that when it is applied to a vertical surface or an inclined portion, it drops down. Further, if the material has almost no flow property, the problem of dripping does not occur, but it may be difficult to penetrate into the gaps of the steel sheet and the coating may be insufficient.

Therefore, for example, in Japanese Examined Patent Publication No. 3-31754, a temperature-sensitive thixotropic agent is used so that it has almost no flow property at room temperature and exhibits flow property at the initial stage of heating. The PVC sol sealer which solved the above is disclosed.

[0006]

By the way, when the PVC sol sealer is applied at room temperature, even if the PVC sol sealer using the above temperature-sensitive thixotropic agent is used,
It is desirable that the VC sol sealer exhibits almost no flow property. Therefore, when it is applied to a hemming portion or the like, it is general that only the opening portion is closed by the PVC sol sealer while leaving a space inside the gap.

However, when the gap such as the hemming portion is large, the volume of the space inside the PVC sol sealer is large and the amount of air remaining in the space is large.
Therefore, the amount of expansion of air due to the heat during baking becomes large, and the PVC sol sealer may expand or break to form a pinhole. If this happens, the effect as a sealing material will diminish and there will be a problem in terms of rust prevention.
A repair process is required, which requires a large number of man-hours.

The present invention has been made in view of such circumstances, and it is an object of the present invention to prevent swelling and pinhole formation even when a gap such as a hemming portion is large.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention have found that foaming due to air remaining in the form of air pockets inside a construction portion such as a hemming portion largely depends on the viscosity of the PVC sol composition and the gelation rate during bake hardening. I found that As a result of further research, it was found that a composition capable of maintaining the viscosity and gelation rate within a predetermined range can solve the above-mentioned problems and can form a coating film excellent in sagging property and shear adhesion property. Was completed.

That is, the PV of the present invention for solving the above problems
The C sol composition is a polyvinyl chloride plastisol composition for sealing, which comprises a vinyl chloride resin composed of a mixture of a vinyl chloride homopolymer and a copolymer and a plasticizer as essential components, and has a BH type viscosity. Viscosity at 20 ° C measured by No. 7 rotor is 170 (Pa · s) or more 230
Is less than (Pa · s), and the period in the pendulum type viscoelasticity measuring device when baked at 140 ± 2 ° C. is 0.60.
The time until it becomes (s) is 14 minutes or more and 20 minutes or less.

As the vinyl chloride resin, both a vinyl chloride homopolymer and a copolymer of vinyl chloride and another vinyl monomer such as vinyl acetate are used. The homopolymer alone may not have sufficient coating properties such as adhesion,
This is because the copolymer alone does not sufficiently reduce the viscosity at the time of bake curing and the appearance quality is not sufficient. Then, by adjusting the ratio of the homopolymer and the copolymer, the viscosity and the gelation rate can be appropriately adjusted.

The mixing ratio of the homopolymer and the copolymer is preferably in the range of 30 to 70 parts by weight of the homopolymer and 30 to 70 parts by weight of the copolymer in 100 parts by weight of the entire vinyl chloride resin. The range of 50 parts by weight or more of the homopolymer and 20 parts by weight or more of the copolymer is particularly desirable. By adjusting the ratio of the homopolymer and the copolymer, the viscosity and the gelation rate can be appropriately adjusted.

As a monomer other than vinyl chloride constituting the above-mentioned copolymer, vinyl acetate is the most common and preferable monomer, but other vinyl esters such as vinyl propionate and vinyl stearate. , Vinyl methyl ether, vinyl isobutyl ether and other vinyl ethers, diethyl maleate and other maleic acid esters, dibutyl fumarate and other fumaric acid esters, methyl acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate and other acrylic acids Esters,
Methacrylic acid esters such as methyl methacrylate and 2-hydroxyethyl methacrylate, acrylonitrile, vinylidene chloride and the like can be mentioned, and one or two of them can be used.
More than one species can be used. These monomers can be copolymerized with vinyl chloride in a proportion of generally 30% by weight or less, preferably 20% by weight or less.

As a plasticizer which mainly constitutes a PVC sol composition together with a vinyl chloride resin, typical examples include dioctyl phthalate (DOP), di-2-ethylhexyl phthalate, diisononyl phthalate (DINP) and phthalate. Phthalates such as octyl butyl acid (OBP),
Examples thereof include di- and tricarboxylic acid esters such as sebacic acid ester and azelaic acid ester, phosphoric acid esters such as triphenyl phosphate and tricresyl phosphate, and epoxy plasticizers such as epoxidized soybean oil.

These plasticizers are appropriately selected and used according to the desired physical properties such as viscosity and curability of the PVC sol composition, and are used in an amount of 10 per 100 parts by weight of the vinyl chloride resin.
A range of 0 to 180 parts by weight is suitable. The viscosity and gelation rate can be adjusted by variously selecting the type and amount of the plasticizer. A part of the plasticizer can be replaced with an organic solvent as a viscosity reducing agent. In this case, as the organic solvent, it is preferable to use an organic solvent having a boiling point as high as that of the plasticizer.

A filler may be mixed with the PVC sol composition of the present invention. Examples of the filler include calcium carbonate, magnesium carbonate, carbonates and sulfates of alkaline earth metals such as barium sulfate, mica, silica, talc, diatomaceous earth, kaolin, calcium oxide, etc., and these may be used alone or in combination. It is possible to use a combination of species. In addition, organic powders such as cellulose powder and powdered rubber can be used if necessary.

The amount of the filler compounded is preferably in the range of 30 to 200 parts by weight with respect to 100 parts by weight of the vinyl chloride resin. If it is less than 30 parts by weight, the cohesive force becomes insufficient,
If it exceeds 200 parts by weight, it becomes brittle and the flexibility and adhesiveness deteriorate. Also, by selecting various types and amounts of filler,
The viscosity and gelation rate can be adjusted. As other components, an adhesiveness-imparting agent, a stabilizer, a thixotropy-imparting agent or other additives can be added as in the conventional case. The adhesiveness-imparting agent enhances the adhesion of the PVC sol coating film to the article to be coated, and includes an epoxy-based, acrylic-based,
Conventionally used adhesion promoters such as polyamide-based and isocyanate-based can be used. Among them, polyamide, block urethane prepolymer, block isocyanurate and the like are particularly preferable.

Stabilizers include zinc, lead, barium,
Salts of metals such as tin and calcium can be used as usual. As the thixotropy imparting agent, those conventionally used such as surface-treated calcium carbonate and ultrafine silica powder can be used. The greatest feature of the PVC sol composition of the present invention is that the viscosity at 20 ° C. measured by No. 7 rotor of BH type viscometer is 170 (Pa · s) or more and 230 (Pa · s).
s), and the time until the cycle in the pendulum type viscoelasticity measuring device when baked at 140 ± 2 ° C. becomes 0.60 (s) is 14 minutes or more and 20 minutes or less.

When the viscosity is lower than 170 Pa · s, sagging tends to occur, and when it is higher than 230 Pa · s, the leveling property is deteriorated and the appearance quality is deteriorated, and the penetrability into the gap such as the hemming part is deteriorated. Blisters are likely to occur. Further, if the time until the cycle becomes 0.60 (s) is less than 14 minutes, gelation becomes too fast and swelling is likely to occur, and if it exceeds 20 minutes, the shear adhesiveness to the article to be coated is deteriorated. Peeling occurs due to interface failure rather than cohesive failure.

By setting the viscosity and the gelation rate within the above ranges, it is possible to obtain a PVC sol composition which has excellent adhesiveness and does not cause swelling or pinholes during baking. In addition, in order to set the viscosity and the gelation rate in the above ranges, the ratio of the homopolymer and the copolymer, the ratio of the vinyl chloride resin and the plasticizer, the selection of the type of the plasticizer, the type and the ratio of the filler, etc. It can be performed by various adjustments.

The PVC sol composition of the present invention can be applied in an arbitrary thickness by a conventional application means.
A coating film can be formed by heating to the same baking temperature of 120 to 160 ° C. as conventional.

[0022]

In the PVC sol composition of the present invention, the viscosity at 20 ° C. measured by No. 7 rotor of BH type viscometer is 170.
Pa · s or more and less than 230 Pa · s, 140 ± 2 ° C
It is configured such that the time taken for the period in the pendulum type viscoelasticity measuring device to be 0.60 s after baking is 14 minutes or more and 20 minutes or less.

Therefore, since the viscosity at room temperature is appropriate, the sagging at the time of application is prevented and the leveling property is excellent. In addition, since the gelling speed during baking is appropriate, it is possible to escape the expanded air and prevent the swelling and pinholes because the holes where the air escaped are blocked and gels. You can

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples. (Example 1) Vinyl chloride / vinyl acetate copolymer (copolymer) 10 parts by weight (PVC blend "G-51" manufactured by Nippon Zeon Co., Ltd.) Vinyl chloride homopolymer (homopolymer) 11 parts by weight (PVC paste " G-121 "made by Nippon Zeon Co., Ltd. Plasticizer OBP (octylbutyl phthalate) 8 parts by weight Plasticizer DINP (diisononyl phthalate) 16 parts by weight Calcium carbonate 25 parts by weight Colloidal calcium carbonate 16 parts by weight Adhesiveness imparting agent ( Block isocyanate) 9 parts by weight (“A-227T” manufactured by Kyoeisha Co., Ltd.) Additive (ultrafine silica, moisture absorbent, etc.) 5 parts by weight ────────────────── ────────────────── Total 100 parts by weight Mixing the raw materials with the above composition and mixing for 30 minutes using a kneader with a decompression device, then 60 minutes The foam of Example 1 PV
A C sol composition was obtained.

With respect to the PVC sol composition of Example 1, its room temperature viscosity and gelation rate at 140 ° C. were measured. Use a BH type viscometer to measure the viscosity of No. 7 rotor at 5r.
The viscosity of the PVC sol composition at 20 ° C. was measured at a rotation speed of pm. Further, the gelation rate was measured by using a pendulum viscoelasticity measuring device (“Vibron DDU-OPA” manufactured by Orientic Co., Ltd.), and the pendulum cycle after heating at 140 ° C. for 15 minutes and the cycle were 0.60 (s). Heating time T until
(Minutes) were measured. An edge type was used as the pendulum, and an average value was obtained three times at intervals of 20 seconds. In addition, 2
The heating time from 0 ° C. to 140 ° C. is 10 minutes. Other Examples and Comparative Examples Table 1 shows the ratio of homopolymer and copolymer of vinyl chloride resin, the ratio of OBP and DINP, and the ratio of calcium carbonate and colloidal calcium carbonate.
Each PVC sol composition was prepared in the same manner as in Example 1 except that various changes were made as shown in FIG. Then, similarly, the room temperature viscosity and the period after heating for 15 minutes and the heating time (T) until the period becomes 0.60 (s) are measured,
The results are shown in Table 1. (Test) Next, each PVC sol composition was applied to an electrodeposited steel sheet using a special jig in a bead shape having a semicircular cross section with a film thickness of 10 μm, and immediately stood vertically and at room temperature for 30 minutes. It was left to stand and then baked at 140 ° C. for 30 minutes.
Then, the sagging of the coating film is visually evaluated, and the results are shown in Table 1 where there is no sagging, ◯ is a little sagging, and markedly sagging is x.

The test pieces shown in FIG.
Apply the C sol composition to a thickness of 1 mm using a special jig,
The state of swelling when baked at 140 ° C. for 30 minutes was visually evaluated. The results are shown in Table 1 with no swelling as ◯, slightly swelling as Δ, and marked swelling as x. In addition, the test piece shown in FIG. 1 is obtained by bonding a peripheral portion of a 60 × 50 mm electrodeposition-coated steel plate 2 to a 150 × 70 mm electrodeposition-coated steel plate 1 in an inclined state to leave a wide space inside. A wire 3 having a wire diameter of 3 mm is interposed between the steel plates 2 and 1, and one end 20 of the steel plate 2 has a height of 4 mm from the steel plate 1.
In the floating state, the steel plate 2 is airtightly adhered to the steel plate 1 at both ends on three sides and one side with an adhesive agent 4. An opening 21 exists in the central portion of the one end 20 of the steel plate 2 that has floated up, and the PVC sol composition is applied so as to close the opening 21. Therefore, a large amount of air exists in the inside sandwiched between the two steel plates, and the expansion force during heating is concentrated in the opening 21, so that a large force acts on the PVC sol composition that closes the opening 21. Has been done.

Further, each PVC sol composition is
Regarding a test piece which was applied to 1 mm on an electrodeposited steel sheet using a dedicated jig and baked at 120 ° C. for 30 minutes JIS-
The shear adhesion test specified in K6829 was performed. If the shear fracture surface is cohesive, ○
The results are shown in Table 1.

[0028]

[Table 1]

(Evaluation) From Table 1, the PVC sol compositions of Comparative Example 1 and Comparative Example 3 are inferior in shear adhesiveness, but the heating time T is as long as 22 minutes and 23 minutes, respectively, and the gelation rate is slow. It is thought to be due to. Further, the PVC sol compositions of Comparative Examples 2, 4 and 5 swell, which is because the heating time T is less than 20 minutes and the gelation time is too short in Comparative Examples 2 and 4. Therefore, it is considered that in Comparative Example 5, the gelling time is short and the room temperature viscosity is too high.

Further, in the PVC sol compositions of Comparative Example 3 and Comparative Example 6, sagging occurs because the room temperature viscosity is less than 170 Pa · s. However, in the PVC sol compositions of the examples, the viscosity is in the range of 170 to 230 Pa · s, and the heating time T is in the range of 14 to 20 minutes. No sagging or sagging occurs and good physical properties are obtained.

Although the embodiments of the present invention have been described above, the embodiments of the present invention have the following embodiments of technical matters in addition to the technical matters described in the claims. Please note that. (1) 8 to 14 parts by weight of vinyl chloride homopolymer, 7 to 13 parts by weight of vinyl chloride copolymer, 5 to 11 parts by weight of octylbutyl phthalate, and 13 to 19 parts by weight of diisononyl phthalate. And 13 parts of colloidal calcium carbonate
The polyvinyl chloride plastisol composition is characterized by comprising 35 to 47 parts by weight of a filler containing 19 to 19 parts by weight.

[0032]

The PVC sol composition of the present invention is capable of preventing swelling and pinholes during baking while maintaining anti-sagging property, and has good adhesiveness with an object to be coated. Sealing with excellent rust can be reliably performed.

[Brief description of drawings]

FIG. 1 is a perspective view of a test piece used for a swelling test according to an example of the present invention.

[Explanation of symbols]

1, 2: Electrodeposition coated steel plate 3: Wire 4: Adhesive 21: Opening

Claims (1)

[Claims] 1. A polyvinyl chloride plastisol composition for sealing, comprising a vinyl chloride resin comprising a mixture of a vinyl chloride homopolymer and a copolymer and a plasticizer as essential components, comprising a BH type viscometer. No. 7 rotor has a viscosity of 170 (Pa · s) or more and less than 230 (Pa · s) at 20 ° C., and the period in the pendulum type viscoelasticity measuring device when baked at 140 ± 2 ° C. is 0. A polyvinyl chloride plastisol composition, wherein the time until it reaches 60 (s) is 14 minutes or more and 20 minutes or less.