JPS6248787A - Hot-melt type thermosetting body sealer - Google Patents

Abstract

PURPOSE:The titled body sealer, obtained by incorporating respectively specific epoxy resin with styrene based block copolymer, tar based softener, curing agents, etc., in a specific proportion and molding the resultant mixture and capable of well sealing up the joint parts of coated sheet metal by baking. CONSTITUTION:A body sealer obtained by incorporating (A) 25-35wt% polybutadiene-modified epoxy resin with (B) 17-23wt% one ore more copolymers selected from the respective block copolymers of styrene-isoprene, styrene-butadiene-styrene and styrene-ethylene-butylene-styrene, (C) 10-20wt% tar based softener, (D) 1-3wt% curing agent having >=100 deg.C curing temperature and (E) 25-35wt% inorganic filler and molding the resultant mixture into a sheet form. EFFECT:Improved adhesive property to base boards of sealing parts, capable of preventing water permeation and having improved peeling resistance, high shear strength and rust preventing effect and beautiful external appearance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a hot melt type thermosetting body sealer.

[Prior Art] For example, in production lines for passenger cars, buses, etc., body sealers are used to seal joints of painted sheet metals. In short, a body sealer is carried on the joints of sheet metals, and then the joints are sealed by baking this body sealer. Conventional body sealers are often liquid products, but in this case, it is necessary to apply masking tape around the joints and then apply 75V of body sealer, which is not only time-consuming but also requires a lot of work afterward. It is necessary to remove the masking tape, and when doing so, the paint on the sheet metal may also peel off. In addition, conventional products include those based on vinyl chloride resin, or
Urethane resins are known, but the former have the disadvantage that the sealing surface is brittle after baking, and the latter tends to foam when heated.

Therefore, in recent years, in order to improve these shortcomings, a hot melt type body sealer in the form of a tape has been proposed, which uses ethylene-vinyl acetate as a single material and contains a tackifier, a plasticizer, etc. ing. however,
Since this conventional body sealer is in the form of a tape, it is preferable because it does not have the drawbacks mentioned above, but it
Since the base material is thermoplastic synthetic resin such as vinyl acetate copolymer, the disadvantage is that when the body sealer is baked and reheated, the seal part softens and melts, reducing the adhesion of the seal to the substrate. There is.

[Objective of the Invention and Means for Solving the Invention] In view of the above circumstances, the present inventors have developed a body in which the adhesion of the seal does not change even when reheated after baking, the strength of the body sealer after baking is high, and the appearance is good. As a result of various studies to obtain a sealer, it was discovered that a thermosetting body sealer prepared based on a specific epoxy resin and a styrene block copolymer was particularly excellent, and the present invention was completed.

[Summary of the Invention] That is, the gist of the present invention is as follows: 025-35% by weight polybutadiene-modified epoxy resin, 17-23% by weight styrene-isoprene block copolymer (SIS), styrene-butadiene-styrene block Copolymer (SB
S) and at least one styrenic block copolymer selected from styrene-ethylene/butylene-styrene block copolymer (SEBS), tar-based softener of 0.10 to 20% by weight, ■1 to 3% by weight The curing temperature is 100℃
The present invention provides a hot melt type thermosetting body sealer characterized in that the above curing agent and an inorganic filler of 0.25 to 35% by weight are mixed and then formed into a sheet.

[Structure of the invention] The present invention will be explained in detail below.

The body sealer of the present invention uses a polybutadiene-modified epoxy resin and a styrene block copolymer as a base material, and the styrene block copolymer is a styrene-isoprene block copolymer (SIS).
, styrene-butadiene-styrene block copolymer (
SBS) and styrene-ethylene/butylene-styrene block copolymer (SEBS). Note that two or more of these components may be used in combination. % polybutadiene, preferably 22% by weight of W Bi. If the amount of these ingredients is too small or too large, it will be difficult to find 1q of the appropriate body sealer.

Furthermore, in the present invention, a tar-based softener is blended as a diluent to uniformly mix the above-mentioned base material, and a hardening agent is blended to harden the base material during baking, but as a tar-based softener, Any material that can uniformly mix the above-mentioned epoxy resin and styrene-based block copolymer may be used. For example, the product commercially available under the trade name "Why 1-Turclon" (manufactured by Kureha Chemical Co., Ltd.) is a typical example. used. To explain this representative example in more detail, this softener consists of a mixture of the following five components a) to e).

a) Lubricating oil base oil (tar product) obtained by hydrorefining or cracking of petroleum fractions or residual oils b) Coumarone-indene copolymer C) Petroleum resin (C8-10 aromatic hydrocarbon fraction polymer) d) Petroleum resin (C4-5 hydrocarbon fraction, C8-10 aromatic hydrocarbon fraction copolymer solid) e) Di(or tri)
Ethyl biphenyl The blending amount of this tar-based softener is 10~
The amount is 20% by weight, preferably 12 to 15% by weight; if this amount is too small, it is difficult to obtain a homogeneous mixture, and if it is too large, it tends to be difficult to form a sheet-like product later. . On the other hand, as a hardening agent, a hardening agent that does not harden at room temperature but hardens when baked at 100'C or higher is used, and specifically, for example, dicyandiamide, imidazole modified product, boron fluoride modified polyamide resin, etc. can be mentioned. The amount of this hardening agent is 1
-3% by weight, preferably 2-2.5% by weight; if this amount is too small, the polymer base material will not be cured well and a good seal will not be obtained during baking;
There is no difference in the effect even if there are many, so it is not practical.

Furthermore, the body sealer of the present invention contains an inorganic filler, and examples of this filler include powdered materials such as calcium carbonate, silica, and mica. The blending amount of the filler is 25 to 45% by weight, preferably 30 to 35% by weight. The blending amount is within the range described above so that a suitable sheet-like body sealer can be obtained.

In the present invention, the above-mentioned predetermined components are uniformly mixed and this is formed into a sheet-like product such as a tape. However, in the present invention, other components may be added in small amounts to the extent that the effects of the present invention are not impaired. There is no problem. The thickness of the sheet-like material varies somewhat depending on its intended use, but is usually about 1 to 4 mm.

When using the body sealer of the present invention, for example, after pasting the sheet-like body sealer of the present invention on the joints of painted sheet metal, it is heated to a temperature of, for example, 110 to 200'C according to a conventional method. By heating the body sealer for about 10 to 60 minutes, the body sealer can be completely baked onto the painted sheet metal.

[Effects of the Invention] According to the present invention, since the body sealer is a thermosetting body sealer having a specific composition, it is possible to seal joints of painted sheet metal well by baking. Further, even after baking, the seal portion does not soften or melt due to external heating, and the reliability of the seal remains unchanged. Further, the present invention has the advantage that the seal portion has excellent adhesion to the substrate, has high peeling resistance and shear strength, and has a beautiful appearance. Therefore, water penetration through the seal portion is prevented, and the rust prevention effect is also high.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the description of the following Examples unless it exceeds the gist thereof. In addition, in the examples, "part" indicates "monomeric part".

Example 1 Polybutadiene-modified epoxy resin (manufactured by Nippon Soda) 2
5 parts, styrene-isoprene block copolymer manufactured by Nippon Synthetic Rubber Co., Ltd.>20 parts, tar-based softener (manufactured by Kureha Chemical Co., Ltd., trade name: White Tarclone) 15 parts, polyamide resin 5 parts, and calcium carbonate powder 35 parts were uniformly mixed. mix, then
This mixture was molded into a tape-like product with a thickness of 3 mm and a width of 45 mm to produce the body sealer of the present invention.

When the tape-shaped body sealer obtained in this way is pasted onto the seam of a test coated sheet metal and the sheet metal is baked under the conditions shown in Table 1, the physical property values of each seal obtained are calculated. The results shown in Table 1 were obtained.

In addition, in the sealed portions obtained through these tests, the body sealer adhered well to the painted sheet metal and had a beautiful appearance.

Table 1 (Note) Measurement method in the example ■Peel strength kg/25mm) JIs, 6854 adhesive According to peel adhesion strength test method.

Test pieces JIS, G, 3141 5PCC Uses polished steel (t2=1.6mm) ■ Shear strength kg/cm 2) JIS, 6850 adhesive According to the tensile wire breaking adhesive strength test method.

Test pieces

Claims (1)

[Claims] (1) [1] 25-35% by weight polybutadiene-modified epoxy resin, [2] 17-23% by weight styrene-isoprene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS) and at least one styrenic block copolymer selected from styrene-ethylene-butylene-styrene block copolymer (SEBS), [3] 10 to 20% by weight of a tar-based softener, [4] 1 to 3% by weight % of a curing agent with a curing temperature of 100° C. or higher and [5] 25 to 35% by weight of an inorganic filler are mixed together, and the mixture is then formed into a sheet shape. .