Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/16—Ethene-propene or ethene-propene-diene copolymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers

Definitions

• the present invention relates to improvements in or relating to foams of ethylene propylene diene copolymer rubbers (hereinafter referred to as EPDM) and formulations for their production.
• Foams of ethylene propylene diene copolymer rubbers are known and are used for sealing in a variety of industrial outlets such as the provision of seals in automobiles to prevent ingress of water which can lead to corrosion of metal components.
• the foams can be used to provide acoustic baffles to reduce noise.
• sealing members of a variety of products of various industrial fields including, for example, automobiles, electric and electronic products, and housing products, to seal up spaces between members or parts of those products, including, for example, exterior sealing material of automobiles, sealing material of electric and electronic products, and sealing material of housings, in the form of dust-proof material, heat insulating material, noise insulation material, vibration-proof material, cushioning material, sealing material, and water shutoff material, for the purposes of dust proof, heat insulation, noise reduction, damping, shock-absorbing, and water and air tight.
• the foams of ethylene propylene diene copolymer rubbers are produced by extrusion to form a sheet of the foam which is then cut to produce pieces of the desired size and shape for the particular application.
• This has the disadvantage that a considerable amount of scrap is generated and also an extensive production line involving extrusion, control of foaming, cooling, cutting and scrap recovery is required.
• the present invention therefore provides an ethylene propylene diene copolymer formulation which can be used to produce foamed articles by injection moulding which produces minimal scrap and enables the foamed articles to be produced in a single moulding operation.
• the compatibilizer enables the formulation to have the desirable properties so that it flows in the injection chamber and the mould.
• the compatibilizer is a polyethylene wax with a melting point in the range 90 0 C to 110 0 C.
• the amount of polyethylene wax that should be used depends upon the nature of the ethylene propylene diene polymer that is employed, the degree of expansion required and the temperatures involved in the moulding cycle. However we prefer to use from 10 to 30 parts of compatibilizer per 100 parts of total ethylene propylene diene copolymer.
• liquid ethylene propylene diene copolymer functions as a viscosity reducer to enable flow of the formulation in the barrel of the injection moulding machine, through the injection nozzle and in the mould.
• liquid ethylene propylene diene rubbers often have a high degree of unsaturation which aids in the cross-linking of the formulation in the mould.
• blowing agent system may be thermally activated to liberate a foaming gas and, as such, may be inorganic or organic.
• the blowing agent may be a liquid that is vaporised on heating to cause foaming.
• the blowing agent system is a mixture of heat activated organic and inorganic blowing agents.
• Preferred organic foaming agents include, for example, azo compounds, such as azodicarbonamide (ADCA), barium azodicarboxylate, azo- bisisobutyronitrile (AIBN), azocyclohexylnitrile, and azodiaminobenzene, N-nitroso compounds, such as N.N'-dinitrosopentamethylenetetramine (DPT), N.N'-dimethyl- N.N'-dinitrosoterephthalamide, and trinitrosotrimethyltriamine, hydrazide compounds, such as 4,4'- oxybis(benzenesulfonylhydrazide)(OBSH), paratoluene .tsulfonyl- hydrazide, diphenylsulfone-3,3 1 - disulfonylhydrazide, 2,4 -toluenedisulfonylhydrazide, p,p-bis(benzenesulf
• Thermally expandable fine particles comprising thermally expandable material encapsulated in microcapsules may be used as the organic foaming agent.
• Commercially available products such as, for example, Microsphere ((Trade name) available from Matsumoto Yushi-Seiyaku Co., Ltd.) may be used as the organic foaming agent.
• organic foaming agents cited above may be used singly or in combination of two or more.
• blowing agent that should be used in relation to the ethylene propylene diene copolymer (EPDM) materials.
• a preferred amount of the blowing agent system to EPDM is, for example, in the range of 0.1-40 parts by weight, or preferably 5-30 parts by weight, per 100 parts by weight of the total amount of EPDM.
• the mixing ratio thereof is, for example, in the range of 5-40 parts by weight, or preferably 10-30 parts by weight, per 100 parts by weight of EPDM.
• N-nitroso compound is used as the blowing agent, the mixing ratio thereof is, for example, in the range of 0.1-40 parts by weight, or preferably 5-30 parts by weight, per 100 parts by weight of EPDM.
• the blowing agent system is a mixture of an organic and inorganic blowing agent and any suitable combination may be used.
• any suitable combination may be used.
• combination of the organic foaming agent and the inorganic compound for example, azodicarbonamide (ADCA) or N 1 N 1 - dinitrosopentamethylene tetramine (DPT) used as the organic foaming agent, and sodium hydrogen carbonate may be used as the inorganic foaming agent which releases gas at a slightly lower temperature. This enables continuous gas generation over a wider temperature range and is useful if an open cell foam structure is required.
• ADCA azodicarbonamide
• DPT N 1 N 1 - dinitrosopentamethylene tetramine
• sodium hydrogen carbonate may be used as the inorganic foaming agent which releases gas at a slightly lower temperature. This enables continuous gas generation over a wider temperature range and is useful if an open cell foam structure is required.
• the ratio that should be used depends upon the nature of the foam required. If open cell foam is required, it is preferred that the ratio of the organic foaming agent to the inorganic foaming agent (organic foaming agent/inorganic foaming agent) is, for example, in the range of 20/1 to 0.1/1, preferably 9/1 to 1/1 , or further preferably 6/1 to 1/1 , by weight.
• the mixing ratio of organic foaming agent is above the mixing ratio specified above, the foams obtained result in closed cell foams, while on the other hand, when the mixing ratio of organic foaming agent is below the mixing ratio specified above, the foams may not be obtained due to outgassing.
• the temperature at which the blowing agent system operates can be controlled by the inclusion in the formulation of a blowing agent activator.
• a blowing agent activator Any suitable blowing agent activator may be used and examples of compounds that may be used include, urea compounds, salicylic acid compounds, and benzoic acid compounds.
• the blowing agent activator may be used singly or in combination of two or more. Urea compounds are preferred as they can lower the decomposition temperature (a foaming temperature) of the organic foaming agent effectively.
• a preferred ratio of the blowing agent activator to EPDM is, for example, in, the range of 2-40 parts by weight, or preferably 5-10 parts by weight, per 100 parts by weight of EPDM.
• the mixture of this blowing agent activator can provide a lower decomposition temperature (foaming temperature) of the organic foaming agent.
• This can allow two- stage foaming whereby the organic foaming agent is foamed first (primary foaming), and, then, the inorganic foaming agent is foamed (secondary foaming), this allows foaming over a wider temperature range to allow the foam of EPDM thus obtained to have open-cell structure.
• mouldings produced by the injection moulding of the formulations of the present invention has a non-cellular skin formed around the foam. This has been found to be particularly useful in the production of materials which provide a combination of sealant and acoustic barrier properties, particularly so when the foam is open cell.
• ingredients may be incorporated into the formulation in order to aid processing and to impart desirable properties to the finished moulding.
• examples of other materials that may be incorporated include fillers, softeners, vulcanizing agents, and vulcanization accelerators, stiffeners, vulcanizing auxiliary agents, and lubricants, and, if required, plasticizers, antioxidants, pigments, colorants, fungicides, and flame retardants, may be included as required.
• Fillers that may be used include, for example, inorganic fillers, such as calcium carbonate (e.g. calcium carbonate heavy), magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silicic acid and its salts, clay, talc, mica powder, bentonite, silica, alumina, aluminum silicate, acetylene black, and aluminum powder, organic fillers, such as cork, and other known fillers. These fillers may be used singly or in combination of two or more. Calcium carbonate is a preferred filler.
• a mixing ratio of the filler to EPDM is, for example, 300 parts by weight or less, or preferably 200 parts by weight or less, per 100 parts by weight of EPDM.
• a preferred formulation contains from 100 parts to 200 parts by weight of filler per 100 parts by weight of total EPDM.
• Softeners that may be used include, for example, drying oils and animal and vegetable oils (e.g. linseed oil), petroleum-derived oils (e.g. paraffinic process oil, naphthenic process oil, and aromatic process oil), asphalts, low-molecular polymers, organic esters (e.g. phthalic ester (e.g. di-2-ethylhexyl phthalate (DOP), dibutyl phthalate (DBP)), ester phosphate, higher fatty acid ester, and ester alkylsulfonate), and tackifier. These softeners may be used singly or in combination of two or more.
• phthalic ester e.g. di-2-ethylhexyl phthalate (DOP), dibutyl phthalate (DBP)
• a preferred mixing ratio of the softener to EPDM is, for example, in the range of 20- 300 parts by weight, or preferably 50-200 parts more preferably 50-100 parts by weight, per 100 parts by weight of EPDM.
• the softener is used in this mixing ratio, the EPDM foams can have a desirable flexibility.
• Vulcanizing agents are preferably included to enhance the cross linking of the material in the mould due to the unsaturation provided by the diene in the ethylene, propylene diene copolymers and in particular in the liquid copolymer.
• the vulcanizing agent should be selected so that it will enhance the cross linking of the material at the temperatures that prevail in the mould but does not cause excessive cross linking in the barrel or the injection chamber of the injection moulding machine.
• the vulcanizing agent and the blowing agent should be selected so that foaming and cross linking occur in the mould to enable the desired foam to be produced.
• Vulcanizing agents that may be used include, for example, sulfur, sulfur compounds (e.g. 4,4'-dithiomorpholine), selenium, magnesium oxide, lead monoxide, organic peroxides (e.g. cumene peroxide), polyamines, oximes (e.g. p-quinonedioxime, p,p'- dibenzoylquinondioxime, etc.) nitroso compounds (e.g. p-dinitrosobenzene), resins (e.g. alkylphenol-formaldehyde resin, melamine-formaldehyde condensate, etc.), and ammonium salts (e.g. ammonium benzoate).
• sulfur compounds e.g. 4,4'-dithiomorpholine
• selenium magnesium oxide
• lead monoxide organic peroxides (e.g. cumene peroxide)
• polyamines oximes (e.g. p-quinoned
• vulcanizing agents may be used singly or in combination of two or more.
• Sulfur is preferably used for durability, resulting from vulcanization of open-cell foam of EPDM.
• Vulcanizing efficiencies vary depending on the type of the vulcanizing agent used, so a mixing ratio of vulcanizing agent can be properly selected.
• a mixing ratio of sulfur to EPDM is, for example, in the range of 0.1-10 parts by weight, or preferably 0.5-3 parts by weight, per 100 parts by weight of EPDM.
• Vulcanization accelerators may also be used and those that may be used include, organic accelerators such as thiazoles (e.g. 2-mercaptobenzothiazole, dibenzothiazyl disulfide, etc.).
• organic accelerators such as thiazoles (e.g. 2-mercaptobenzothiazole, dibenzothiazyl disulfide, etc.).
• Inorganic accelerators may also be used such as dithiocarbamic acids (e.g. sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, etc.), guanidines (e.g. diphenylguanidine, di-o-tolylguanidine, etc.), sulfenamides (e.g.
• vulcanization accelerators may be used singly or in combination of two or more.
• Dithiocarbamic acids are preferably used in terms of vulcanizing speed and others.
• a preferred mixing ratio of the vulcanization accelerator to EPDM is, for example, in the range of 0.5-10 parts by weight, or preferably 1-5 parts by weight, per 100 parts by weight of EPDM.
• the vulcanizing accelerator used is not limited to any particular one; zinc oxide is a preferred vulcanizing accelerator.
• a mixing ratio of the vulcanizing accelerator agent to EPDM is, for example, in the range of 1-20 parts by weight, or preferably 2-10 parts by weight, per 100 parts by weight of EPDM.
• vulcanization retardants such as, for example, organic acids (e.g. phthalic anhydride, benzoic acid, salicylic acid, etc.) and amines (e.g. N-nitroso-diphenylamine, N-nitroso-phenyl- - naphthylamine, etc.), may be used to control foaming in the mould.
• organic acids e.g. phthalic anhydride, benzoic acid, salicylic acid, etc.
• amines e.g. N-nitroso-diphenylamine, N-nitroso-phenyl- - naphthylamine, etc.
• stiffener carbon black is particularly suitable.
• a preferred mixing ratio of the stiffener to EPDM is, for example, in the range of 0.1-80 parts by weight, or preferably 0.5-50 parts by weight, per 100 parts by weight of EPDM.
• a mixing ratio of the lubricant to EPDM is, for example, in the range of 0.5-5 parts by weight, or preferably 1-3 parts by weight, per 100 parts by weight of EPDM.
• the formulations of the present invention may be produced in any suitable manner.
• the EPDM 1 the filler, the softener and other additives are properly selected and mixed at the desired mixing ratio. Then, the mixture is kneaded using a kneader, a mixer, a mixing roll, and the like; to prepare intimate mixture. Afterwards the vulcanizing agent, the organic, foaming agent, the inorganic foaming agent, the vulcanization accelerator, and the foam auxiliary agent are further mixed in the intimate mixture in the proper manner, the mixture is further kneaded using the mixing roll and then heated.
• the desired expansion ratio of the EPDM will depend upon the use to which the moulding is to be put and it can be controlled by selecting the nature and amount of blowing agent and the expansion permitted in the mould.
• the expansion ratio can range from, 100% to 3000% expansion as determined by the ratio of the density of the material before being foamed to the density of the foam after foamed useful mouldings for automobile sealings can be produced with expansion ratios of 100% to 500%. By setting the expansion ratio to be in the range of 1000% to 3000%, good sealing properties can be developed and moderate flexibility can be obtained.
• the expansion ratio can be adjusted by adjusting the mixing ratio of the organic foaming agent and inorganic foaming agent, and the vulcanizing foaming time and temperature.
• the foam of EPDM of the present invention When used as a sealing material, it can ensure the good foam filling even for an object to be sealed of large area, low in strength, or small in space.
• the foams produced according to the present invention may be used in any of the applications described above and are particularly useful to provide sealants and/or associated barriers particularly in transportation vehicle such as automobiles, aerospace vehicles, trucks and railroad. Other applications include vibration damping adhesive overmoulding, overmoulding of foams onto attachments such as clips. Examples of suitable injection moulding techniques are the injection presses provided by rep and described in rep news.
• the formulation was blended and then introduced into the feeding chamber of an injection moulding machine which was heated to bring the temperature of the formulation to a temperature in the range 80 0 C to 100 0 C.
• the heated formulation then passed to the injection chamber of the machine which was held at a temperature in the range 80 0 C to 120 0 C.
• the formulation was then injected from the injection chamber into a cylindrical mould which was held at 190 0 C 1 the injection speed was 29 mm/sec and the amount of material injected into the mould was sufficient to allow an expansion of 243% in the mould. After injection the material was held within the mould for 7 minutes to allowing curing.
• the moulding produced is shown in Figure 1 and consists of a moulded disc having a cellular core and an unfoamed outer skin.
• Figure 2 shows another moulding obtained from the same formulation showing how the foamed structure can be created around an attachment pin.

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• Chemical & Material Sciences (AREA)
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• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
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• 2007
  • 2007-02-20 GB GB0703248A patent/GB0703248D0/en not_active Ceased
• 2008
  • 2008-02-20 EP EP08715890A patent/EP2115049A1/de not_active Withdrawn
  • 2008-02-20 WO PCT/EP2008/001319 patent/WO2008101685A1/en active Application Filing

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