JP2006045329A - Foamed molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide foamed moldings usable as a sealant that maintains sealing property and shows improved workability. <P>SOLUTION: A composition including 100 pts.mass of EPDM, 0.1 to 10 pts.mass of a vulcanizing agent, 0.1 to 10 pts.mass of a vulcanization accelerator and 0.5 to 50 pts.mass of a thermally foaming agent is vulcanized and foamed 1.1 to twofold to obtain molded foam having a density of 0.6 to 0.9 g/cm<SP>3</SP>, a durometer hardness of 20 to 40 and a stress of 0.2 to 2.0 MPa in 50% compression. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a foam molded body, and more particularly to a foam molded body used as a sealing material.

  As pipes such as sewers and drainage channels buried in the ground, fume pipes, ceramic pipes, etc. are widely used. The inner walls of these conduits are eroded by hydrogen sulfide and other corrosive gases and deposits, which can reduce the strength of the tube walls. In addition, if a gap in the pipe joint or a crack in the pipe itself occurs due to the influence of earth pressure or ground subsidence, inflow of groundwater into the pipe or leakage outside the pipe will occur, and the area around the pipe The earth and sand flow out, and a hollow portion is generated on the outer peripheral surface of the pipe, which causes the road surface to collapse.

  As a means for repairing the pipe line in order to solve the above problem, after assembling the fitting body into a cylindrical shape along the pipe length direction of the pipe line, a curable filler is placed in the gap between the fitting body and the pipe inner surface. Means for injecting is known (see, for example, Patent Document 1). In this means, a sealing material such as synthetic rubber or water-expandable rubber is interposed in the fitting portion of the fitting body. This sealing material is used by being attached to the fitting member with an adhesive member or the like. However, due to the weight of the sealing material, there is a problem that peeling between the sealing material and the adhesive member and peeling between the adhesive member and the fitting member occur. Further, when synthetic rubber is employed as the sealing material, there has been a problem that the synthetic rubber itself deteriorates with time and the elasticity is lowered, and a gap is generated in the fitting portion.

  There is also known a method in which a water leakage is stopped by pressing an annular rubber band with a band-shaped steel band from the inside of a pipeline to a repair portion of the pipeline (see, for example, Patent Document 2). However, this method has a problem that a rubber band for preventing water leakage has to be pressure-bonded with a steel band at a very strong pressure, and that the rubber band is deteriorated due to a change with time and water leaks again.

Vulcanized foams of ethylene / propylene trimer system (hereinafter referred to as EPDM) are widely used because they have excellent cushioning properties and compressibility, as well as sealing materials for water-stopping and heat insulation / soundproofing. However, these vulcanized foams are foamed at a high magnification, and have a defect that the compressive stress is too low and deforms under high water pressure, resulting in poor water stopping performance (see, for example, Patent Document 3).
JP 2001-311387 A (2nd page: claims 1 to 22) Japanese Patent No. 3045753 (2nd page: Claim 1) JP-A-10-45933 (2nd page: claims 1 to 6)

  The subject of this invention is providing the foaming molding which can be used as a sealing material which maintained water stop and improved workability | operativity.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by a foamed molded product obtained by subjecting a specific rubber composition to vulcanization and foaming treatment at a specific expansion ratio, and have completed the present invention. .

That is, the present invention comprises a composition comprising 100 parts by weight of EPDM, 0.1 to 10 parts by weight of a vulcanizing agent, 0.1 to 10 parts by weight of a vulcanization accelerator, and 0.5 to 50 parts by weight of a heating foaming agent. Vulcanized and 1.1 to 2 times foamed density 0.6 to 0.9 g / cm ³ , durometer hardness 20 to 40, 50% compression stress is 0.2 to 2.0 MPa It is a foaming molding characterized by these.

  The foamed molded article of the present invention is a foam obtained by using EPEM, which is less deteriorated by changes over time, as a rubber component, foaming with a contained pyrolyzable foaming agent, and vulcanizing the rubber component. Thereby, since weight reduction was achieved, maintaining long-term stability and intensity | strength, it has the effect that it can prevent falling off with the dead weight from the adhesive member of the repair part of a pipe line. Moreover, since the stress at the time of 50% compression is in a specific range, the disadvantage that the water stop performance is deteriorated by losing the water pressure under high water pressure is improved, and the water stop performance against water leakage can be improved.

  The rubber composition of the present invention is obtained by uniformly dispersing and holding a vulcanizing agent, a vulcanization accelerator, a thermally decomposable foaming agent, and the like to be described later.

  In this invention, EPDM can use 1 type (s) or 2 or more types from various EPDM, and there is no limitation in particular. Examples of the diene constituting EPDM include 5-ethylidene-2-norbornene, 5-propylidene-5-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, 5-methylene-2-norbornene, and 1,4-hexadiene. 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 2,3-diisopropylidene-5-norbornene and the like. Among these, 5-ethylidene-2-norbornene is particularly preferable as an EPDM foam excellent in heat resistance and weather resistance.

  The vulcanizing agent and vulcanization accelerator of the present invention improve the degree of crosslinking of the rubber component and improve the strength of the resulting foamed molded product itself.

  Examples of the vulcanizing agent include sulfur-based compounds including sulfur-containing compounds such as sulfur, polysulfide, and sulfur chloride, oxime-based compounds such as p-quinonedioxime and pp-dibenzoylquinoneoxime, t-butyl hydroperoxide, There are organic peroxides such as acetylacetone peroxide and cumene hydroperoxide. As long as the vulcanizing agent includes at least a sulfur-based one, a plurality of types may be used in combination. The amount of these vulcanizing agents used is preferably 0.1 to 10 parts by mass, particularly 0.5 to 5 parts by mass per 100 parts by mass of EPDM. If the vulcanizing agent is less than 0.1 parts by mass, vulcanization is not sufficient, and if it exceeds 10 parts by mass, the vulcanizing agent tends to bloom.

  The use of a vulcanization accelerator is preferred for the purpose of accelerating the vulcanization treatment. Examples of the vulcanization accelerator include thiurams such as tetramethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide, and thiazoles such as 2-mercaptobenzothiazole and dibenzothiazole disulfide. Dithiocarbamates such as zinc dimethyldithiocarbamate and zinc diethyldithiocarbamate, aldehyde amines such as n-butyraldehyde aniline, sulfenamides such as N-cyclohexyl-2-benzothiazylsulfenamide, diorthotolylguanidine And guanidine compounds such as diorthonitrile guanidine, thiourea compounds such as thiocarbanilide, diethylthiourea and trimethylthiourea, and zinc white compounds. The vulcanization accelerator may be used in combination of not only these simple substances but also two or more kinds. These vulcanization accelerators are used in an amount of 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, per 100 parts by weight of EPDM. If the vulcanization accelerator is less than 0.1 parts by mass, the effect of vulcanization acceleration is small, and if it exceeds 10 parts by mass, it becomes difficult to control the vulcanization speed and the vulcanization accelerator tends to bloom.

Examples of the heating foaming agent include azo foaming agents such as azodicarbonamide, azobisisobutyronitrile, azodiaminobenzene, azocyclohexylnitrile, N, N′-dinitrosopentamethylenetetramine, N, N′-dimethyl. Nitroso-based blowing agents such as N, N′-dinitrosoterephthalamide, sulfonyls such as benzenesulfonyl hydrazide, p, p′-oxybis (benzenesulfonyl hydrazide), toluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonyl hydrazide Organic foaming agents such as hydrazide foaming agents and inorganic foaming agents such as ammonium bicarbonate, ammonium carbonate, sodium hydrogen carbonate, ammonium nitrite and calcium azide can be used. Although the usage-amount of a foaming agent should just adjust suitably according to the physical property of the target foam, 0.5-50 mass parts with respect to 100 mass parts of EPDM, especially 1-20 mass parts is preferable. If the heating foaming agent is less than 0.5 parts by mass, foaming is not sufficient, and if it exceeds 50 parts by mass, it may be difficult to control the expansion ratio.
Moreover, you may use a foaming adjuvant together with these as needed. Examples of the foaming aid include salicylic acid, phthalic acid, stearic acid, oxalic acid, uric acid or derivatives thereof.

The compression stress is preferably 50% compression stress and 0.2 to 2.0 MPa. Here, if the 50% compressive stress is less than 0.2 MPa, the adhesion with the material to be sealed is poor and the sealing performance is lowered. On the other hand, when the pressure is larger than 2 MPa, it is difficult to compress to a predetermined thickness, and workability is lowered. Particularly preferred is 0.5 to 1.0 MPa.

  The foamed molded product of the present invention is obtained by kneading a rubber composition containing these components, molding the rubber composition into a desired shape, and performing foaming treatment and vulcanization treatment.

As an apparatus for producing a rubber composition, there are kneading apparatuses such as conventionally known mixers, Banbury mixers, kneader mixers, two rolls, etc., and as apparatuses for molding the obtained rubber composition, conventionally known press molding, There are molding devices such as extrusion molding and calendar molding. In general, a rubber composition is extruded into a product shape with a rubber extruder, then introduced into a vulcanizing tank, and vulcanized and foamed by heating by means of hot air, fluidized bed, microwave or the like. I can do it. Note that the vulcanization treatment and the foaming treatment may be performed in separate steps or simultaneously.
Moreover, what is necessary is just to design the shape of a foaming molding according to a use suitably, such as a sheet form and a tape form. The foaming ratio suitable for a waterproof seal is 1.1 to 2 times, preferably 1.2 to 1.5 times in that good mechanical strength and flexibility can be obtained. The density of the foamed molded article obtained at this expansion ratio is preferably 0.6 to 0.9 g / cm ³ . When the density is less than 0.6, since the compression and repulsive force of the foam are small, the water stop effect cannot be sufficiently obtained, and the water stop at the initial stage of installation is lowered. On the other hand, if it exceeds 0.9, the flexibility of the sealing material is reduced and the weight is increased, which leads to problems such as poor workability on the mounting portion and peeling of the sealing material.

  The deurometer hardness of the foamed molded body is preferably 20 to 40, and preferably 25 to 35. When the hardness exceeds 40, it is difficult to exhibit high sealing properties when the foamed molded product is attached to a non-smooth part. When the hardness is less than 20, the water stoppage is lowered by water pressure. The hardness of the molded body can be adjusted mainly by the expansion ratio, but a softener or the like may be used in some cases.

  The foamed molded product of the present invention is an inorganic filler, plasticizer, anti-aging agent, processing aid, lubricant, and tackifier used in ordinary vulcanized rubber compounds within the range that does not impair the effect. An agent or the like may be contained. Examples of the inorganic filler include silica, diatomaceous earth, alumina, zinc oxide, titanium oxide, magnesium oxide, iron oxide, zinc borate, boric acid, calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, hydrotalcite, Aluminum hydroxide, magnesium hydroxide, calcium sulfate, barium sulfate, calcium silicate, talc, clay, mica, bentonite, activated clay, sepiolite, glass fiber, glass beads, aluminum nitride, boron nitride, carbon black, graphite, carbon fiber These may be used alone or in combination of two or more. The particle size of the inorganic filler is preferably 1 to 50 μm from the viewpoint of dispersibility in the rubber component. Carbon black functions as a reinforcing agent and is effective in reducing the compression strain of the resulting foamed molded article. Examples of softeners that are also effective in adjusting moldability include paraffinic and naphthenic process oils, liquid paraffin, other paraffins, waxes, synthetic polymer softeners such as silicone oil and liquid polybutene, Examples thereof include ester plasticizers such as phthalic acid, adipic acid, sebacic acid and phosphoric acid, stearic acid and esters thereof, and alkylsulfonic acid esters. These softeners can also be expected to act as plasticizers.

  The foamed molded product of the present invention can be selected from various shapes, but a tape shape is generally preferred. The foamed molded product may be affixed to the fitting member with a commercially available double-sided tape or adhesive, and may be joined by nailing, screwing, or the like.

  The following is mentioned as an example in which the foaming molding of the present invention is used suitably as repair of a pipe line. That is, as described in Patent Document 1, a hollow frame-shaped reinforcing body is assembled on the inner surface of the pipe using a reinforcing member that can be carried into the pipe, and a plurality of fitting members are provided inside the reinforcing body. After fitting and fitting the inner surface members and assembling these fitting bodies into a cylindrical shape along the circumferential direction of the pipe line, repairing is performed by injecting a curable filler into the gap between the fitting body and the pipe inner face. In this method, the foamed molded product of the present invention is attached to the fitting member to prevent water leakage of the fitted product. Further, as described in Patent Document 2, when the annular rubber band is pressure-bonded to the water leakage portion of the pipe from the inner surface with a band-shaped steel band, the gap between the rubber band and the inner face of the pipe is You may use for the method of interposing a foaming molding.

  For the inner surface member and the fitting member, metals such as polyethylene resins for sewer pipes, olefinic thermoplastic resins, unsaturated polyester resins, fiber reinforced resins, and stainless steel can be used. The hollow frame-shaped reinforcing body is made of a highly rigid material made of steel or the like. As the curable filler, for example, a cement-based material such as cement milk, mortar, concrete, or a thermosetting resin such as an epoxy resin can be used, and is selected according to required performance, cost, and the like. The cyclic rubber band is a synthetic rubber having necessary strength, durability, and elasticity, and chloroprene rubber, isoprene rubber, acrylonitrile / butadiene rubber, ethylene / trimer and the like can be used.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but these examples do not limit the present invention. In addition, the part and% in the following description are based on a mass reference | standard.

"Example 1 to Example 4"
The materials used in this example are as shown below.
(1) EPDM: ethylene / propylene / 5-ethylidene-2-norbornene copolymer (DSM Japan Co., Ltd., “Keltan 6640B”) or ethylene / propylene / dicyclopentadiene copolymer (Sumitomo Chemical Co., Ltd.) "Esplen 305")
(2) Vulcanizing agent: Powdered sulfur (manufactured by Hosoi Chemical Co., Ltd.)
(3) Vulcanization accelerator: N-cyclohexyl-2-benzothiazylsulfenamide (manufactured by Ouchi Shinsei Co., Ltd., “Noxeller CZ”), tetramethylthiuram disulfide (manufactured by Daishin Shinsei Co., Ltd., “Noxeller”) TT "), zinc oxide (manufactured by Sakai Chemical Co., Ltd.," Zinc Hana 3 ")
(4) Heating foaming agent: azodicarbonamide (manufactured by Shiroishi Calcium Co., Ltd., “Serogen AZ”), p, p′-oxybis (benzenesulfonylhydrazide)) (manufactured by Shiroishi Calcium Co., Ltd., “Serogen OT-1”) Urea compound (manufactured by Eiwa Kasei Co., Ltd., “Cell Paste 101W”)
(5) Inorganic filler: White carbon (Nippon Silica Co., Ltd., “Nip seal VN3”)
(6) Plasticizer: Di-n-octyl phthalate (“N-DOP” manufactured by Daihachi Chemical Co., Ltd.)
(7) Anti-aging agent: 4,4 ′-(α, α-dimethylbenzyl) diphenylamine (manufactured by Ouchi Shinsei Co., Ltd., “NOCRACK CD”)
(8) Carbon black: “# 60” manufactured by Asahi Carbon Co., Ltd.
(9) Softening agent: Process oil (manufactured by Nippon Sun Oil Co., Ltd., “Thumper 150”)
(10) Adhesive: Polybutene (manufactured by BP Amoco, “H300”)

"Rubber composition"
The ingredients shown in Formulation A in Table 1 were kneaded for 2 minutes at 120 ° C. using a kneader mixer with a capacity of 3 liters. Next, while kneading the obtained kneaded material with two rolls, the components shown in Formulation B of Table 1 were added and kneaded for 5 minutes to obtain a rubber composition.
"Foamed molded product"
The rubber composition obtained by kneading was extruded into a belt shape with a rubber extruder equipped with a die having a width of 20 mm and a thickness of 10 mm, and then heated at 160 ° C. for 20 minutes using a hot air vulcanizing tank. Vulcanization treatment and foaming treatment were performed to obtain a foamed molded article.

In this example, each characteristic described below was evaluated and summarized in Table 1. The measuring method of each characteristic is shown below.
Density: Measured with an electronic hydrometer (MIRAGE TRADING CO., LTD: EW120SG) according to JIS K-6268.
Hardness: Performed according to JIS K-6253.
50% compressive stress: Performed according to JIS K-6767.
Water stop pressure: As shown in FIG. 1, a ring-shaped foamed molded article (1) having an outer diameter of 30 cm, an inner diameter of 27.5 cm, and a thickness of 1 cm was bonded to a water stop pressure tester (2) made of steel having an outer diameter of 50 cm. After fastening with a bolt (3) at a compression rate of 50% and filling the water stop pressure tester (2) with water, the water pressure immediately before the occurrence of water leakage was measured by applying water pressure.
Presence or absence of water leakage: The foamed molded product was held at a water pressure of 0.05 MPa for 1 month in the testing machine of FIG.
Ozone resistance: An ozone deterioration test was performed according to JIS K-6259, a strip sample was stretched by 20% at 40 ° C. and 50 ppm ozone concentration, and the presence or absence of cracks on the surface of the molded article after 96 hours was observed.

"Comparative Examples 1-3"
In Comparative Examples 1 to 3, the compounding of the rubber composition of Example 1 was changed to the materials and compounding amounts described in Table 2, respectively, to obtain a molded product by the same method as in Example 1, and each characteristic was obtained. It has been evaluated. The evaluation results for each characteristic are summarized in Table 2.
In Comparative Example 3, the rubber used was SBR rubber (styrene / butadiene copolymer “JSR1712” manufactured by JSR Corporation).

Sectional view schematically showing the still water pressure tester according to the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Foam molding 2 Water stop pressure tester 3 Bolt 4 Water inlet 5 Water outlet 6 Water pressure gauge

Claims (3)

Composition formed by blending 0.1 to 10 parts by mass of vulcanizing agent, 0.1 to 10 parts by mass of vulcanization accelerator, and 0.5 to 50 parts by mass of heating foaming agent with 100 parts by mass of ethylene / propylene trimer. The product was vulcanized and foamed at a foaming ratio of 1.1 to 2 times, a density of 0.6 to 0.9 g / cm ³ , a durometer hardness of 20 to 40, and a 50% compression stress of 0.2 to 2. A foamed molded article characterized by being 0 MPa.   2. The foam molded article according to claim 1, wherein the ethylene / propylene trimer is an ethylene / propylene / 5-ethylidene-2-norbornene copolymer. The sealing material of the fitting part which consists of a foaming molding of Claim 1 or Claim 2.

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