JPH04132758A - Vinyl chloride plastisol composition - Google Patents

Abstract

PURPOSE:To obtain a vinyl chloride plastisol composition giving a coating film having excellent crack resistance and suitable as a sealing material effective in improving the rust-proofness of the joint part, etc., of steel plate by compounding a plasticizer and a filler to a vinyl chloride resin having a specific particle size. CONSTITUTION:The objective composition is produced by compounding (A) a vinyl chloride resin having particle diameter of <=2mum with (B) a plasticizer containing a polyester-based plasticizer and/or a benzyl-type plasticizer accounting for >=50% of the total plasticizer and (C) a filler (e.g. ground calcium carbonate having an average particle diameter of <=10mum).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a vinyl chloride plastisol composition that is applied as a sealant to improve rust prevention by being applied to joints of steel plates, etc. The present invention relates to a vinyl chloride plastisol composition that can prevent cracking of paint films.

[Prior Art] Automobile bodies and the like are assembled by stacking a plurality of steel plates and joining them by welding or adhesive. Welding is often performed by spot welding, and the spot spacing is several tens of millimeters, so the sealing between the steel plates is not perfect. Furthermore, even when joining with adhesive, since the steel plates are treated with anti-corrosion oil, etc., the application of the adhesive is insufficient and the sealing performance is not perfect. The assembled body is then electrocoated to give rust prevention properties to the POD steel plates.However, the above-mentioned steel plate joints have a clearance of less than 1mm, making it difficult for the electrocoating to penetrate, making the coating impossible. It is enough. For these reasons, vinyl chloride plastisol sealants are used in steel plate joints to improve rust prevention. In addition to the above-mentioned sealing properties, the required properties of this sealing material include paintability. The sealant is a heat-curing type, and after being applied, it is heated and cured. A top coat is then applied to enhance the design of the car. However, since the sealant has a vinyl chloride resin as a matrix, its paintability is somewhat inferior to that of steel sheets, and there is a demand for improved paintability. For example, JP-A-6
Publication No. 2-53544 discloses a vinyl chloride-based highly permeable sealing material composition with improved sealing properties. Further, Japanese Patent Application Laid-Open No. 63/309579 discloses a vinyl chloride resin sealing material with improved paintability and good leveling properties. However, although these sealants have excellent sealing properties and paintability, it is often difficult to prevent cracks from occurring in the top coat coated on the top surface of the sealant. In other words, during the baking process after the paint film is applied, the sealant cannot absorb the distortion that occurs due to the difference in thermal expansion of the bonded steel plates, which causes cracks in the paint film formed on the sealant. Conceivable.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a sealing material that is excellent in removing the paint film.

[Means for Solving the Problems] The vinyl chloride plastisol composition of the present invention is a vinyl chloride plastisol composition containing a powdered vinyl chloride resin, a plasticizer, and a filler. It is characterized in that the particle size of the system resin is 2 um or less.

First, the vinyl chloride resin, which is the most distinctive feature of the present invention, preferably has an average particle size of 2 μm or less in order to improve the cracking resistance of the coating film.

The vinyl chloride resin may be a homopolymer or a copolymer as long as it is a paste-use vinyl chloride resin. The content of vinyl chloride resin in the composition is 15 to 2
Preferably it is 5 parts by weight.

If the content is less than 15 parts by weight, the properties of the sealing material will deteriorate, and if it exceeds 25 parts by weight, storage stability will deteriorate, which is not preferable.

Next, when a polyester plasticizer or a benzyl plasticizer is used in combination as a plasticizer, the coating film cracking resistance can be further improved. The amount used is that either polyester plasticizer or benzyl plasticizer or both account for 50% of the total plasticizer.
It is preferable that it is above. If all the plasticizers are polyester plasticizers, the adhesive strength will be poor, and if only benzyl plasticizers are used, the storage stability will be poor.

The average particle size of the heavy calcium carbonate used as a filler is preferably 10 .mu.m or less, particularly 1 to 4 .mu.m.

If the average particle size is larger than 10 μm, the cracking resistance of the coating film decreases, which is not preferable. As fillers, fine particles of colloidal calcium carbonate, silica, zinc oxide, etc. can also be added. Furthermore, adhesion promoters, stabilizers, and the like may be added as additives.

[Function] By using the vinyl chloride plastisol composition of the present invention, a sealing material with excellent crack resistance and good paintability of the coating film formed on the sealing material can be obtained. That is, the strain generated at the joint between the steel plates causes cracks in the coating film on the sealant when the elongation performance limit of the coating film is exceeded. To prevent this, it is necessary to create a form that maximizes the elongation of the coating film. To do this, we need to use vinyl chloride resin and heavy calcium carbonate filler to make the surface of the sealant even and smooth to keep the thickness of the paint film uniform and prevent stress from the joints from concentrating on local areas of the paint film. A finely divided product is used. Furthermore, in order not to impair the smoothness of the coating film, we use plasticizers such as polyester or benzyl.
To eliminate the influence of a plasticizer on a coating film so as not to affect coating film formation. By selecting the powder material and plasticizer for the sealant in this way, the coating film can exhibit sufficient elongation and its cracking resistance is improved.

[Example] Hereinafter, this will be explained in detail using examples.

Vinyl chloride resin (average degree of polymerization 1400, particle size 1-2 μm
), 10 parts by weight of a vinyl chloride copolymer (average degree of polymerization 1200, particle size 1-2 μm) containing 5% vinyl acetate, and a polyester plasticizer (phthalic acid type, number average molecular weight 600-700). 13 parts by weight, alkylbenzyl plasticizer (alkyl group, C number 4 to 8), 24 parts by weight, heavy calcium carbonate (particle size 2 to 4 μm), 16 parts by weight of colloidal calcium carbonate, and other additives (adhesion). Adding agent, stabilizer) 14 parts by weight were blended to make Ziering material No. 1.
was created. It was produced in the same manner by blending Nos. 2 and 3 of Ziering materials No. 1 to 4 of Examples 1 to 4 in the proportions shown in the table. The molecular weight of the polyester plasticizer was determined by calculating the number average molecular weight by GPC.

(Left below) (Evaluation method) 1. Scratch resistance: The prepared sol was applied to a plate to be coated to a width of 15 mm and a thickness of 2 mm, and after calcining at 100°C for 10 minutes, an alkyd melamine resin intermediate coating was applied. , apply an acrylic melamine resin top coat at 140℃ x 3
After baking for 0 minutes, immediately after taking it out of the oven, gradually bend it along a 378-inch round bar at an angle of 10 degrees and 15 seconds until cracks occur in the coating film.
A case where the bending angle at that time was 100 degrees or more was considered acceptable.

Elongation: Apply the sealant to the plate to be coated and bake at 140℃ for 60 minutes to determine the elongation of the sealant using JASOM-323-7.
Measured according to 7.

Storage stability: The sol was stored in a constant temperature bath at 45° C. for 72 hours and evaluated based on the presence or absence of gel formation. N01 as shown in the table
), 20 parts by weight of vinyl chloride resin with a particle size of 1 to 2 μm,
The plasticizer was 100% polyester-based and benzyl-based, and by incorporating heavy calcium carbonate with a size of 4 μm or less, the coating film had excellent one-blind abrasion resistance, elongation, and storage stability. In the composition ranges of No. 2.3 and 2.3 of the present invention, all exhibit excellent coating resistance, elongation, and storage stability.

On the other hand, Comparative Example No. 1. No. 2 has a particle size of 30 to 40μ
When a coarse-grained vinyl chloride resin of m is used, the spreadability of the coating film is poor. No. 3 is a case where the plasticizer DOP is used, and the cracking resistance is insufficient due to the influence on the solvent of the top coat. No. 4 is a case where only a benzyl plasticizer is used, and the storage stability of the sealant is decreased.

Effect] The vinyl chloride plastisol composition of the present invention is composed of a vinyl chloride resin and a filler having small particle sizes, and 50% or more of the plasticizer is occupied by a polyester type and a benzyl type. Since the resin and filler of the sealant are made of fine particles in this way, a surface with few irregularities is formed, and the coating film applied to the top surface becomes a uniform film, allowing maximum elongation. Moreover, since it does not have an adverse effect on the coating film formation of polyester-based or benzyl-based plasticizers, a smooth coating film can be formed.

Therefore, the cracking resistance of the coating film is improved, and the paintability is also improved, resulting in a coating film with improved hue and gloss. The physical properties of the paint film are also improved because the sealant absorbs stress and its effect on the paint film is reduced.

Patent applicant: Aisin Kako Co., Ltd. Representative Haruo Miyaji

Claims (1)

[Claims] (1) A vinyl chloride plastisol composition containing a powdered vinyl chloride plastisol composition, a plasticizer, and a filler, characterized in that the particle size of the powdered vinyl chloride resin is 2 μm or less. Vinyl chloride plastisol composition.