JPH08120257A - Gasket - Google Patents

Abstract

PURPOSE: To provide a gasket which is excellent in compression set, creep resistance, weatherability, resistance to heat aging, tear strength, etc. CONSTITUTION: The gasket is produced from a vinyl chloride resin compsn. mainly comprising 100 pts.wt. vinyl chloride resin. 10-200 pts.wt. acrylic rubber contg. crosslinked tetrahydrofuran-insols., 1-50 pts.wt. acrylic resin, and 30-300 pts.wt. plasticizer having a wt.-average mol.wt. of 430 or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasket having excellent compression set, creep resistance, weather resistance, tear strength and heat aging resistance.

[0002]

2. Description of the Related Art Gaskets are used in parts where airtightness and sealability are required, and are used in automobiles such as weather strips, glass run channels, trunk packings, roof moldings, packings, joint materials, electrical equipment, and construction. Used for applications such as materials. Conventional gaskets
Highly polymerized or partially crosslinked vinyl chloride resins have been used, and vulcanized rubber has been used. However, the vinyl chloride resin alone has problems that the compression set is inferior, the sealing property is deteriorated, and that the vulcanized rubber cannot be obtained in an arbitrary shape, and cannot be recycled because it is thermosetting. . As an improved method, a technique of improving compression set by adding partially crosslinked acrylonitrile-butadiene rubber (hereinafter referred to as NBR) to vinyl chloride resin is disclosed in JP-A-56-115342 and JP-A-57-157342.
Although disclosed in Japanese Laid-Open Patent Publication No. 187341 and the like, NBR is used as a rubber component, so that these materials have poor weather resistance and cannot be used for a long period of time due to deterioration.

Further, JP-A-1-256554 discloses a vinyl chloride resin, an acrylic rubber containing an insoluble component in tetrahydrofuran (hereinafter referred to as THF), and a plastic for the purpose of improving shape retention at high temperature and weather resistance. Compositions of agents are disclosed. However, since a general-purpose plasticizer is not used and an acrylic resin is not contained, there are drawbacks that the heat aging resistance after long-term use is poor and the tear strength is particularly small.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides an elastomer composition containing vinyl chloride resin, a rubber substance, a plasticizer and the like as main components, which are excellent in heat aging resistance and tear strength.
And, as a result of earnestly studying for the purpose of obtaining a gasket that does not impair compression set, creep resistance, weather resistance,
It was found that a gasket comprising a vinyl chloride resin containing an acrylic rubber containing a THF-insoluble crosslinking component, an acrylic resin, and a plasticizer having a weight average molecular weight of 430 or more achieves the above-mentioned object, and completes the present invention. Came to. That is, an object of the present invention is to provide a gasket made of a vinyl chloride resin elastomer composition having excellent physical properties such as compression set, creep resistance, weather resistance, heat aging resistance and tear strength.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is to provide an acrylic rubber 10 containing 100 parts by weight of a vinyl chloride resin and an insoluble crosslinking component in tetrahydrofuran.
Gasket made of vinyl chloride resin elastomer composition containing 200 parts by weight, 1 to 50 parts by weight of acrylic resin and 30 to 300 parts by weight of a plasticizer having a weight average molecular weight of 430 or more as main components, and particularly, the composition is formed into a band shape. The present invention is a gasket having a cross section of T-shape, L-shape, F-shape, E-shape, hollow shape or a combination thereof.

The present invention will be described in detail. The vinyl chloride resin, which is the main resin component of the vinyl chloride resin elastomer composition that is a constituent of the gasket of the present invention, is a suspension polymerization method of vinyl chloride or a mixture of vinyl chloride and a comonomer copolymerizable therewith. Any of those produced by ordinary methods such as a bulk polymerization method, a fine suspension polymerization method or an emulsion polymerization method can be used. Examples of comonomers include vinyl acetates such as vinyl acetate, vinyl propionate, and vinyl laurate, acrylic acid esters such as methyl acrylate, ethyl acrylate, and butyl acrylate,
Methacrylic acid esters such as methyl methacrylate and ethyl methacrylate, maleic acid esters such as dibutyl maleate and diethyl maleate, fumaric acid esters such as dibutyl fumarate and diethyl fumarate, vinyl methyl ether, vinyl butyl ether, vinyl octyl ether. Vinyl ethers such as acrylonitrile, vinyl cyanides such as methacrylonitrile, α-olefins such as ethylene, propylene and styrene, vinylidene chloride, vinylidene halides or vinyl halides other than vinyl chloride such as vinyl bromide, Examples thereof include polyfunctional monomers such as diacrylic phthalate and ethylene glycol dimethacrylate. Of course, the comonomers are not limited to those mentioned above. The comonomer content is 30% by weight or less, preferably 20% by weight or less in the constituent components of the vinyl chloride resin.

The average degree of polymerization of the vinyl chloride resin is not particularly limited, but it is 70 from the viewpoint of workability and moldability.
0-8000, preferably 1000-4000, especially 1
It is preferably in the range of 300 to 3,500. The acrylic rubber contained in the vinyl chloride resin-based elastomer composition is a synthetic rubber containing an acrylic ester such as an alkyl acrylate or an alkoxyalkyl acrylate as a main component, and the synthetic rubber contains an acrylic acid derivative as a main component,
Copolymers with functional monomers such as alkyl methacrylate, acrylonitrile and styrene are also included in the category. The acrylic rubber needs to contain a cross-linking component insoluble in tetrahydrofuran (THF), and preferably contains 30 wt% or more, more preferably 50 wt% or more of the cross-linking component. In order to introduce the crosslinking component into the acrylic rubber, for example, a crosslinking monomer such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, propylene glycol dimethacrylate is reacted. When the amount of the THF-insoluble crosslinking component is small, the compression set characteristic of the elastomer composition becomes poor.

The amount of acrylic rubber added is in the range of 10 to 200 parts by weight, preferably 20 to 150 parts by weight, based on 100 parts by weight of the vinyl chloride resin, and the optimum range is from 30 to 120 parts by weight. To be selected. If the amount of acrylic rubber added is less than 10 parts by weight, the effect of improving compression set is small, and if it exceeds 200 parts by weight, the physical properties such as tear strength, elongation, and heat aging resistance are remarkably deteriorated.

The above-mentioned THF-insoluble cross-linking component means that 0.5 g of acrylic rubber is added to 30 ml of THF while stirring,
The solution is left standing at 23 ° C. for 24 hours to elute THF-soluble matter, filtered through a glass fiber filter paper, and the weight of the insoluble residue after drying is determined to calculate the content of the crosslinking component.
The plasticizer used in the vinyl chloride resin elastomer composition must have a weight average molecular weight of 430 or more, and a plasticizer having a weight average molecular weight (MW) of less than 430 cannot improve tear strength. Also, the long-term heat aging resistance is poor.

As these plasticizers, diisodecyl phthalate (MW447) and diundecyl phthalate (MW
475) and the like, phthalate ester plasticizers of higher alcohols, tris (2-ethylhexyl) phosphate (MW
435), trisdichloropropyl phosphate (MW
431) and other phosphate ester plasticizers, dibutyldiglycol adipate (MW435) and other adipic ester plasticizers, tri (2-ethylhexyl) trimellitate (MW547) and other trimellitic ester plasticizers, adipic acid, Aliphatic dibasic acids such as sebacic acid and azelaic acid, aromatic dibasic acids such as phthalic acid, and 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol And polyester plasticizers obtained by esterifying aliphatic glycols such as 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 1,8-octanediol and trimethylhexanediol. To be Among these plasticizers, a polyester plasticizer or a mixture of a polyester plasticizer and another plasticizer is preferable. A polyester plasticizer having a weight average molecular weight of up to about 8,000 is suitable, and preferably 1,000 to 5
000, particularly in the range of 1000 to 2000 is desirable.

Epoxy fatty acid ester (MW400
~ 500) or epoxidized oil-based plasticizer (MW about 100)
It is also possible to use 0) together. Although the amount of the plasticizer used varies depending on the type and amount of the vinyl chloride resin, acrylic rubber, etc., the presence or absence of the filler, etc., it is preferably 30 to 300 parts by weight, preferably 100 to 100 parts by weight of the vinyl chloride resin. It is appropriately selected from the range of 40 to 200 parts by weight.

The acrylic resin to be blended with the vinyl chloride resin elastomer composition means one obtained by polymerizing acrylic acid or a derivative thereof. Acrylic acid, acrylic ester, acrylamide, acrylonitrile, methacrylic acid, methacrylic acid. Examples thereof include polymers such as esters and copolymers. Particularly, in the vinyl chloride resin elastomer composition for gaskets of the present invention, a copolymer of methyl methacrylate and alkyl acrylate, the former of which is 60% by weight or more, preferably 70 to 90% by weight and the latter of 40% by weight or less. It is suitable to use the one in the range of not more than 10% by weight, preferably in the range of 30 to 10% by weight. The amount of acrylic resin added is 1 to 100 parts by weight of vinyl chloride resin.
It is desirable that the amount is 50 parts by weight, preferably 3 to 30 parts by weight. If it is less than 1 part by weight, the effect of improving the tear strength of the gasket is small, and if it is more than 50 parts by weight, it becomes hard and loses elasticity.

It is desirable to add a filler to the vinyl chloride resin elastomer composition for a gasket of the present invention within a range that does not impair compression set and other physical properties. The filler has the function of absorbing an excessive amount of plasticizer and facilitating kneading and molding. Examples of the filler include carbon black, calcium carbonate, titanium oxide, talc, aluminum hydroxide, magnesium hydroxide, hydrotalcite, clay, silica and white carbon. The amount of the filler added is 150 parts by weight or less, preferably 10 to 100 parts by weight, based on 100 parts by weight of the vinyl chloride resin. If the addition amount of the filler is too small, the effect of improving kneading and moldability is small, and if it is more than 150 parts by weight, the moldability tends to be deteriorated, and it is economical to add it within a range that does not impair the moldability. It is also desirable from the viewpoint of sex.

Further, the vinyl chloride resin elastomer composition may contain stabilizers, lubricants, antioxidants, ultraviolet absorbers, foaming agents, flame retardants, pigments, impact modifiers, and thermoplastic resins other than those mentioned above, if necessary. You may mix | blend various additives, such as rubber. Examples of the thermoplastic resin and the rubber include methyl methacrylate-butadiene-styrene rubber (MB
S), acrylic rubber (AR) soluble in THF, butadiene rubber (BR), styrene-butadiene rubber (SB
R), acrylonitrile-butadiene-styrene rubber (ABS), isoprene rubber (IR), chloroprene rubber (CR), ethylene-propylene rubber (EPR), ethylene-vinyl acetate (EVA), thermoplastic polyurethane (TPU), nylon, etc. Is mentioned.

The vinyl chloride resin elastomer composition is
A vinyl chloride resin, an acrylic rubber containing a THF insoluble cross-linking component, a plasticizer having a weight average molecular weight of 430 or more, an acrylic resin and, if necessary, various other additives such as a filler are charged into a mixer or a kneader in a predetermined amount. , 100 to 230 ° C,
It is preferably produced by a method of uniformly mixing and kneading each component while heating at a temperature of 130 to 230 ° C. The produced composition is molded into a gasket by a molding machine, for example, into a strip shape and a T-shaped, L-shaped, F-shaped, E-shaped, or hollow shape or a combination thereof.

The above composition is also useful as a composite gasket compounded with a metal or a hard resin. As the hard resin, for example, chlorinated vinyl chloride resin, hard vinyl chloride resin, acrylonitrile-butadiene-styrene resin, etc. can be used. Metals include iron, steel,
Examples include stainless steel, brass, aluminum and the like. As a method of combining a vinyl chloride resin elastomer composition and a hard substance such as metal, for example, a method of extrusion coating the vinyl chloride resin elastomer composition on the entire surface or a part of the surface of the hard substance such as a strip, plate or rod. , A method in which both are co-extruded using a plurality of extruders and combined in an extrusion die or in the vicinity thereof, or a method in which both are manufactured into molded articles by various molding methods and the two are joined by heat welding or an adhesive. Various methods are adopted.

[0017]

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to the following examples without departing from the gist thereof. The vinyl chloride resin elastomer composition and the gasket were evaluated for quality as follows, and the results are shown in Table 1.

[0018]

[Table 1] Measurement of compression set: Measured in accordance with JIS K6301 at 70 ° C. for 22 hours under a 25% compression condition. Tear strength test: Measured based on JIS K6301. Weather resistance test: A sheet of the elastomer composition was prepared by a roll, a press sheet was prepared from the sheet, and a 5 cm square test piece was punched out for use in the weather resistance test. The color difference before and after the weather resistance test was used to determine whether the weather resistance was good or bad. It was judged. The weather resistance test conditions and color difference measurement conditions are as follows. -Weather resistance test conditions Use a sunshine weather meter (manufactured by Suga Test Instruments). Black panel 83 ° C. Spray cycle 60 minutes / 12 minutes (12 minutes water spray in 60 minutes). 450 hours. -Color difference measurement conditions Photometer AUCOLOR VP-1 (manufactured by Kurashiki Spinning Co., Ltd.) was used.
Light is applied to the surface of the test piece and the reflected light is measured with a spectrophotometer. The difference in reflected light intensity on the surface of the test piece before and after the test was taken as the color difference. The larger the value, the greater the color change. Elongation measurement: Measured according to JIS K6723. Heat aging resistance test: In accordance with JIS K6723, the heating condition was 100 ° C. × 500 hours, the elongation after heating aging was measured, and the elongation residual rate was determined by the following formula. Residual elongation (%) = (elongation after aging / elongation before aging) x 100 Gasket deformation rate: 70 ° C according to JIS K6301
The deformation ratio of a gasket having a length of 5 cm was measured under the condition of 50% compression for 22 hours.

Examples 1 to 4 and Comparative Examples 1 to 6 [Production of Composition] 100 parts by weight of a vinyl chloride resin having an average degree of polymerization of 2350, plasticizers and acrylics of the types and amounts (parts by weight) shown in Table 1 were used. 3 parts by weight of resin and Ba-Zn composite stabilizer, 1 part by weight of phosphite chelator, 0.4 part by weight of lubricant, 1 part by weight of UV absorber and 30 parts by weight of calcium carbonate were mixed in a beaker, The type and amount of acrylic rubber or NBR shown in 1 were added and mixed. These are rolled with an 8-inch mill and the surface temperature is 160
Kneading was carried out at 0 ° C for 5 minutes. A press sheet was prepared from a roll sheet obtained by kneading to obtain a test piece.

[Molding of Gasket] These roll sheets were pelletized by a sheet cutting method. The pellets were extruded on a 20 mmφ extruder with an outer diameter of 16.5 mm and an inner diameter of 13.
A 5 mm tube-shaped molded product was prepared. The tube molded product was bonded onto a stainless plate having a thickness of 1 mm to prepare a gasket.

[0021]

[Table 2]

[0022]

[Table 3] The raw materials in Table-1 used in the examples are as follows. Plasticizer Phthalic acid type 1 Phthalic acid dialkyl ester of MW452 (mixture of alkyl groups C ₉ to ₁₁ ) Polyester type 1 MW1300 Polyester of adipic acid and butanediol (Terminal 2-ethylhexanol) Polyester type 2 MW1800 Adipic acid and butanediol of polyester Le (terminal 2-ethylhexanol) DOP di-2-ethylhexyl phthalate (MW391) DINP (mixed alkyl C ₇ ~ ₁₁₎ diisononyl phthalate (MW418) adipic acid dialkyl esters of adipic acid 1 MW387 acrylic resin Methyl methacrylate / alkyl acrylate = 70 to 90/30 to 10% by weight Rubber substance Acrylic rubber 1 THF insoluble crosslinking component 93.9% by weight (prototype) Acrylic rubber 2 THF insoluble crosslinking component None (commercially available product) NBR THF insoluble crosslinking component 89.4% by weight acrylonitrile content 30% by weight

[0023]

Since the gasket of the present invention comprises a vinyl chloride resin, an acrylic rubber containing a THF-insoluble cross-linking component, an acrylic resin and a plasticizer having a weight average molecular weight of 430 or more, it is particularly resistant to heat aging and tear strength. Is excellent.

Claims (7)

[Claims] 1. 100 parts by weight of a vinyl chloride resin, 10 to 200 parts by weight of an acrylic rubber containing an insoluble crosslinking component in tetrahydrofuran, 1 to 50 parts by weight of an acrylic resin, and 30 to 300 parts by weight of a plasticizer having a weight average molecular weight of 430 or more. A gasket made of a vinyl chloride resin-based elastomer composition containing as a main component. 2. The gasket according to claim 1, wherein the gasket is a composite with a metal or a hard resin. 3. The gasket according to claim 1 or 2, wherein the vinyl chloride resin as a main component has an average degree of polymerization of 700 to 8000. 4. The gasket according to claim 1, wherein the acrylic rubber contains 30% by weight or more of an insoluble crosslinking component with respect to tetrahydrofuran. 5. The gasket according to claim 1, wherein the plasticizer is a polyester plasticizer. 6. The weight average molecular weight of the plasticizer is 1000-8.
The gasket according to any one of claims 1 to 5, which is in a range of 000. 7. The method according to claim 1, further comprising a filler.
The gasket according to any one of items.