JP2001226663A - Thermosetting foamable sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermosetting foamable sealing material composition capable of reducing an amine smell resulting from a blowing agent, not causing scorching of cured material, improving the structural strength of a hollow body when a thermosetting foamable sealing material is arranged in the hollow body, is cured and expanded by heating and filled into the inside of the hollow body. SOLUTION: This thermosetting foamable sealing material composition comprises an epoxy resin component (A), a curing agent (B), an inorganic blowing agent (C) and a filler (D) as main components. The inorganic blowing agent (C) is one or more kinds of compounds selected from sodium hydrogencarbonate, sodium carbonate, sodium azide, sodium borate and sodium citrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting foamed sealing material composition which is installed in a hollow body such as a body side seal, a floor member, a pillar, etc. of an automobile, and which is cured and foamed to improve structural strength. It is.

[0002]

2. Description of the Related Art In recent years, as a method of improving the structural strength of a vehicle body, a method of foaming and filling an internal space of a hollow body such as a pillar has been adopted. By attaching a highly elastic foam sealant to the steel plate surface or inserting it into the gap between the steel plates and filling it by heat-curing foaming, high strength can be obtained with a low weight, so that the fuel efficiency of automobiles can be reduced. This method has been attracting attention because it is improved and is cheaper than steel plates.

[0003] Among them, there is a sheet shape (JP-A-9-176).
616), putty-like (JP-A-5-59345), and epoxy-based (JP-A-10-139981).

In general, an organic foaming agent is mainly used because the foaming agent used for these becomes an independent cell and the foaming temperature can be easily controlled. When such an organic foaming agent is used, a substance having an amine odor is contained in the generated gas because nitrogen is mainly used. Therefore, when curing and foaming in an electrodeposition drying oven, a strong amine odor is generated, and it becomes necessary to provide local exhaust equipment and the like during the process. Further, when the pillar portion is not sufficiently sealed, an odor may remain even after an automobile is assembled as a product.

Further, when a thermosetting foam sealing material is used for a portion having a thickness of 5 cm or more, the heat of reaction is trapped inside and the temperature of the central portion of the filler is locally increased because the organic foaming agent is an exothermic reaction. And mechanical strength may be significantly reduced due to scorching. As a means for eliminating burnt, there is a method using a heat absorbing agent. However, aluminum hydroxide or the like has a large specific gravity, and there is naturally an upper limit to the number of blending parts in order to suppress the weight of the filler after foaming.

[0006]

SUMMARY OF THE INVENTION According to the present invention, the internal space of a hollow body such as a pillar is foam-filled without lowering the mechanical strength as described above and suppressing the generation of amine odor during curing. An object of the present invention is to provide a thermosetting foam sealing material composition.

[0007]

In order to achieve the above object, the thermosetting foamable sealing material composition of the present invention comprises an epoxy resin (A), a curing agent (B), and an inorganic foaming agent (C). And a filler (D) as an essential component. The inorganic foaming agent (C) is composed of one or more compounds selected from sodium hydrogen carbonate, sodium carbonate, sodium azide, sodium borate, and sodium citrate.

As a result of intensive studies, the use of the inorganic foaming agent (C) does not reduce the mechanical strength due to scorching,
A thermosetting foam sealing material composition capable of foaming and filling the hollow body internal space while reducing the amine odor generated from the organic foaming agent was obtained.

Examples of the epoxy resin (A) used in the present invention include various epoxy resins having active hydrogen and having excellent adhesion to metals, and modified epoxy resins thereof.
For example, condensation products of epichlorohydrin with polyhydric alcohols or polyphenols such as bisphenol A and bisphenol F, condensation products of epichlorohydrin with novolaks such as phenol novolak and cresol novolak, cycloaliphatic epoxy resins, glycidyl ester-based epoxy Epoxy resin derived from resin or polyolefin polymer or copolymer, epoxy resin obtained by (co) polymerization of glycidyl methacrylate, epoxy resin obtained from glyceride of highly unsaturated fatty acid, polyalkylene ether type epoxy resin (nuclear Polyol-type epoxy resin and polyurethane-skeleton-containing epoxy resin), bromine-containing or fluorine-containing epoxy resin, and the like. These epoxy resins may be used alone or may be used arbitrarily. Were mixed in the ratio may be used.

The curing agent (B) used in the present invention may be a heat-activated curing agent that exerts a curing effect by heating (80 to 200 ° C.), and is not particularly limited. As a resin curing agent, dicyandiamide, 4,4′-diaminodiphenyl sulfone,
Examples include phenol, various acids or acid anhydrides, and polyamides. Then, a curing accelerator may be added to the epoxy resin as needed. Examples of the curing accelerator include imidazole derivatives such as 2-n-heptadecyl imidazole, isophthalic acid or adipic dihydrazide, guanidine-based, N, N-dialkylthiourea derivatives, and the like. The amount of the curing agent and the curing accelerator used is, for example, 3 to 30 parts of the curing agent and 10 parts or less of the curing agent, based on 100 parts by weight of the epoxy resin (hereinafter abbreviated as “parts”).

As the inorganic foaming agent (C) used in the present invention, it is possible to use an inorganic foaming agent containing a foaming gas containing no ammonia such as carbon monoxide or carbon dioxide as a main component and foaming by an endothermic reaction. it can. Naturally, some inorganic foaming agents such as ammonium bicarbonate and ammonium carbonate generate an amine odor, but they are not suitable for the present invention.

Specific examples include sodium hydrogen carbonate, sodium carbonate, sodium azide, sodium borate, sodium citrate and the like. Further, an organic foaming agent may be used in combination, if necessary, for example, when increasing the expansion ratio. As the organic foaming agent, for example, azodicarbonamide, azobisisobutylnitrile, p-toluenesulfonylhydrazide and the like can be used. The mixing amount depends on the expansion ratio, but the epoxy resin (A) 1
The amount is preferably 1 to 20 parts, more preferably 1 to 10 parts with respect to 00 parts. If the amount is less than 1 part, the expansion ratio is too small, and if the amount is more than 20 parts, the amount of generated gas leaks out.

As the filler (D) used in the present invention, for example, magnesium oxide, aluminum oxide, silicon oxide, calcium oxide, titanium oxide (rutile type, anatase type), chromium oxide (trivalent), iron oxide, Zinc oxide,
Silica, diatomaceous earth, alumina fiber, antimony oxide, barium ferrite, strontium ferrite, beryllium oxide, pumice, oxides such as pumice balloons and basic substances or hydroxides such as magnesium hydroxide, aluminum hydroxide, basic magnesium carbonate or Carbonate such as magnesium carbonate, calcium carbonate, barium carbonate, ammonium carbonate, calcium sulfite, dolomite, dawsonite, or (sulfite) such as calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, and basic magnesium sulfate, or silicic acid Sodium, magnesium silicate, aluminum silicate, potassium silicate, calcium silicate, talc, clay, mica, asbestos, glass fiber, montmorillonite, glass balloon, glass beads,
Silicates such as pentonite or kaolin (porcelain), perlite, iron powder, copper powder, lead powder, aluminum powder, tungsten powder, molybdenum sulfide, carbon black, boron fiber, silicon carbide fiber, brass fiber, potassium titanate, Examples thereof include lead zirconate titanate, zinc borate, aluminum borate, barium metaborate, calcium borate, and sodium borate.

As other compounding agents, liquid or solid rubbers such as SBR, CR, acrylic rubber, fine particles of acrylic rubber, NBR, polyurethane, urethane prepolymer and the like can be used as elastomer components.
In addition, fillers such as calcium carbonate and fine-particle silica powder, foam stabilizers, antioxidants, and ultraviolet absorbers may be used to adjust viscosity and thixotropic properties, prevent sagging during heat-curing foaming, and improve foam properties as required. , A colorant can be added.

The thermosetting foamed sealing material is kneaded with a heating kneader or a planetary mixer in a temperature range of 60 to 80 ° C. at which the curing reaction does not proceed, and is uniformly dispersed and extruded into a sheet. Alternatively, it could be obtained by injection into a mold and molding.

[0016]

Next, examples of the present invention and comparative examples will be described.

Example 1 As an epoxy resin component (A), 60 parts of a bisphenol A type liquid epoxy resin (Epicoat # 828, manufactured by Yuka Shell) and a bisphenol A type solid epoxy resin (Epicoat # 1004, oily Prepared by Shell Co., Ltd.) and heated to 60 ° C., 15 L
The mixture was melted and mixed with a planetary mixer. Thereafter, the mixture was transferred to a 2 L kneader, and Nipol 1 was used as an elastomer.
043 (manufactured by Zeon Corporation), 15 parts of dicyandiamide as curing agent (B), 5 parts of sodium hydrogencarbonate as inorganic foaming agent (C), and untreated calcium carbonate SS-80 (Nitto Powder) as filler (D) (Kakosha Co., Ltd.) and uniformly mixed at room temperature for 1 hour to prepare a thermosetting foamable sealing material composition.

(Example 2) The procedure of Example 1 was repeated, except that the inorganic blowing agent (C) was changed to 5 parts of sodium citrate.

Example 3 40 parts of the epoxy resin (A) bisphenol A type solid epoxy resin (Epicoat # 1004, manufactured by Yuka Shell Co., Ltd.) of Example 1 was used as a cresol novolak type solid epoxy resin (ESCN195-10).
The procedure was performed in the same manner as in Example 1, except that 40 parts (manufactured by Sumitomo Chemical Co., Ltd.) were used.

Example 4 Example 1 was repeated, except that the inorganic blowing agent (C) was a mixture of 4 parts of sodium hydrogencarbonate and 1 part of azodicarbonamide.

(Comparative Example 1) The same procedure as in Example 1 was carried out except that the inorganic blowing agent (C) in Example 1 was mixed with 5 parts of azodicarbonamide.

The odor, scorch, compressive strength, expansion ratio and foaming state of the products of Examples 1 to 4 and Comparative Example 1 were measured. In addition, each test was performed by the method shown below.

(Preparation of test piece) 3 cm of Examples and Comparative Examples
Place an uncured block of × 3cm × 3cm on an iron plate,
It was placed in a drier at 170 ° C. for 30 minutes to cure and foam.

(Odor at the time of curing) The odor of the gas generated during the curing and foaming was actually confirmed. X with strong amine odor
Those with an amine odor were rated as △, and those without an amine odor were rated as ○.

(Burning) The center of the cured product prepared as above was halved in the horizontal direction, and the degree of discoloration of the cross section was visually observed. X indicates that the carbonization occurred, Δ indicates discoloration, and O indicates no discoloration.

(Compression Strength) The cured product prepared as described above was cut into blocks of 40 × 40 × 40 mm. Thereafter, the test piece was compressed at a compression rate of 10 mm / min in a 20 ° C. atmosphere using a compression tester, and the compressive strength was calculated from the maximum load at that time.

(Expansion ratio) The specific gravity before and after curing and foaming was measured by a water displacement method, and the expansion ratio was calculated from the value.

(Bubble state) The cured product was halved in the thickness direction at the center, and the cross section was visually observed. ○ indicates uniform foaming, X indicates uneven foaming, and △ indicates the middle.

[0029]

[Table 1]

[0030]

According to the results shown in Table 1, those of Examples 1 to 3 had no odor at the time of curing, and they were not scorched. As described above, by using an inorganic foaming agent, there is no decrease in mechanical strength due to charring, and a thermosetting foam seal that foams and fills a hollow body internal space while reducing an amine odor generated from an organic foaming agent. It was found that a material composition could be obtained.

Claims (2)

[Claims] 1. A thermosetting foam sealing material composition comprising an epoxy resin (A), a curing agent (B), an inorganic foaming agent (C), and a filler (D) as essential components. 2. The heat according to claim 1, wherein the inorganic blowing agent (C) comprises at least one compound selected from sodium hydrogen carbonate, sodium carbonate, sodium azide, sodium borate and sodium citrate. A curable foam sealing material composition.