EP2115049A1 - Injection mouldable foamable ethylene propylene diene copolymer rubber formulations - Google Patents

Injection mouldable foamable ethylene propylene diene copolymer rubber formulations

Info

Publication number
EP2115049A1
EP2115049A1 EP08715890A EP08715890A EP2115049A1 EP 2115049 A1 EP2115049 A1 EP 2115049A1 EP 08715890 A EP08715890 A EP 08715890A EP 08715890 A EP08715890 A EP 08715890A EP 2115049 A1 EP2115049 A1 EP 2115049A1
Authority
EP
European Patent Office
Prior art keywords
parts
weight
formulation according
epdm
per
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08715890A
Other languages
German (de)
French (fr)
Inventor
Sylvain Gleyal
Laurent Meistermann
Christophe Le Bonte
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zephyros Inc
Original Assignee
Zephyros Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zephyros Inc filed Critical Zephyros Inc
Publication of EP2115049A1 publication Critical patent/EP2115049A1/en
Withdrawn legal-status Critical Current

Links

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.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Ethylene propylene diene copolymers are provided that can be processed by injection moulding to produce foamed mouldings by the inclusion of a liquid ethylene propylene diene copolymer and a compatibilizing agent together with standard ethylene propylene diene copolymer, blowing agent and curative in order to provide the desired combination of viscosity for injection moulding and curing and foaming in the mould.

Description

INJECTION MOULDABLE FOAMABLE ETHYLENE PROPYLENE DEIENE COPOLYMER RU BBER, FORM U LATIONS
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. In addition the foams can be used to provide acoustic baffles to reduce noise. Other applications include 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.
Generally 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.
European Patent Publication 1683827 A1 relates to the production of open celled foams of ethylene-propylene-diene rubbers and although it is stated that the formulations can be processed by injection moulding the examples all involve extrusion and the formulations of EP 1683827 A1 are not suitable for injection moulding. The present invention therefore provides an ethylene propylene diene formulation suitable for the production of foams by injection moulding comprising >
i) solid ethylene propylene diene copolymer ii) a liquid ethylene propylene diene copolymer iii) a compatibilizer iv) a blowing agent and v) a curative system.
The requirements for a product that can be injection moulded are more critical than those for a product that can be extruded. Accordingly while products that can be injection moulded can be extruded the reverse does not always apply. For injection moulding formulations must have the appropriate viscosity for flow through the injection nozzle and into the mould. Due to the short residence time in the moulding machine, it is important that the material acquire the desired viscosity rapidly to have the necessary degree of flow and to absorb the high shear to which the fluid material is subjected as it is injected from the injection chamber through the injection nozzle into the mould. In an extrusion process the material has more time in the barrel of the extruder to acquire the desired temperature and the shear to which the material is subjected at the die of an extruder is considerably less than that at the injection nozzle of an injection moulding machine.
The requirements for injection moulding of a foamable ethylene propylene diene copolymer composition are also unique in that an ethylene propylene diene copolymer system is employed that will both foam and cross link in the mould but it should not cross link or foam in the short time in which it resides and is heated within the barrel of the injection moulding machine. Accordingly the ingredients, their proportions and the moulding cycle should be selected to enable this to happen.
The preferred conditions will depend upon the size of the moulding to be produced, the required density and associated degree of foaming, the strength requirements and the nature of the solid ethylene propylene diene copolymer. A typical moulding cycle is that the material is heated in the barrel of the injection moulding machine to a temperature in the range 800C to 1000C, it then passes into the injection chamber of the injection moulding machine is held at a temperature in the range 800C to 1200C from which it is injected into the mould itself which is typically at a temperature in the range 1300C to 2500C preferably in the range 1500C to 2000C depending upon the activation temperatures of the blowing agent and the cross-linking agent.
We have found that the use of the compatibilizer enables the formulation to have the desirable properties so that it flows in the injection chamber and the mould. In a preferred embodiment the compatibilizer is a polyethylene wax with a melting point in the range 900C to 1100C. 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.
The 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. Furthermore, liquid ethylene propylene diene rubbers often have a high degree of unsaturation which aids in the cross-linking of the formulation in the mould. We prefer to use from 5 to 29 parts of liquid ethylene propylene diene copolymer per 100 parts of solid ethylene propylene diene copolymer, more preferably 7.5 to 15 parts.
Ethylene-propylene-diene rubber is a rubber produced by copolymerization of ethylene, propylene, and dienes. By copolymerizing dienes further with ethylene- propylene copolymer to introduce unsaturated bond, vulcanization can be achieved by means of a vulcanizing agent. Examples of suitable dienes that may be used include, butadiene, 5-ethylidene-2-norbornene, 1 ,4-hexadiene, and dicyclopentadiene.
Any suitable blowing agent system may be used. The blowing agent may be thermally activated to liberate a foaming gas and, as such, may be inorganic or organic. Alternatively the blowing agent may be a liquid that is vaporised on heating to cause foaming. In a preferred embodiment the blowing agent system is a mixture of heat activated organic and inorganic blowing agents.
Preferred organic foaming agents that may be used 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-3,31- disulfonylhydrazide, 2,4 -toluenedisulfonylhydrazide, p,p-bis(benzenesulfonylhydrazide)ether, benzene -1 ,3 - disulfonylhydrazide, and allylbis(sulfonylhydrazide), semicarbazide compounds, such as p-toluilenesulfonyl- semicarbazide, and 4,4'- oxybis(benzenesulfonylsemicarbazide), alkane fluorides, such as trichloromonofluoromethane, and dichloromonofluoromethane, and triazole compounds, such as 5- morpholyl-1 ,2,3,4- thiatriazole, and other known organic foaming agents. Preferably, azo compounds and N-nitroso compounds are used. Azodicarbonamide (ADCA) and N1N1- dinitrosopentamethylenetetramine (DPT) are particularly preferred.
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.
The organic foaming agents cited above may be used singly or in combination of two or more.
No particular limitation is imposed on the amount of 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. When an azo compound is used as the organic foaming agent, 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. When an 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.
When an inorganic blowing agent is used suitable blowing agents include, for example, hydrogen carbonates, such as sodium hydrogen carbonate, and ammonium hydrogen carbonate, carbonates, such as sodium carbonate, and ammonium carbonate, nitrites, such as sodium nitrite, and ammonium nitrite, borohydride, such as sodium borohydrides, and other known inorganic foaming agents, such as azides may be used. Preferably, a hydrogen carbonate is used, and the preferred hydrogen carbonate is sodium hydrogen carbonate.
The inorganic foaming agents may be used singly or in combination of two or more.
No particular limitation is imposed on a mixing ratio of the inorganic foaming agent to EPDM. A convenient mixing ratio of the inorganic foaming agent to EPDM is, for example, in the range of 2-40 parts by weight, or preferably 2-20 parts by weight, per 100 parts by weight of EPDM.
In a preferred formulation the blowing agent system is a mixture of an organic and inorganic blowing agent and any suitable combination may be used. No particular limitation is imposed on combination of the organic foaming agent and the inorganic compound. For example, azodicarbonamide (ADCA) or N1N1- 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.
Where a mixture of organic and inorganic blowing agents are used 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. When 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. 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. We have also found that 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.
Other 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. Preferably, petroleum-derived oils and asphalts are used. When petroleum-derived oils and asphalts are used as the softener, excellent heat resistance and weather resistance can be given to the EPDM foams obtained.
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. When 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. Furthermore 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). These 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. For example when sulfur is used as the vulcanizing agent, 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.). 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. benzothiazyl-2- diethylsulfenamide, N-cyclohexyl-2-benzothiazyl sulfenamide, etc.), thiurams (e.g. tetramethylthiurammonosulfide, tetramethylthiuramdisulfide, etc.), xanthogenate (e.g. sodium isopropylxanthogenate, zinc isopropylxanthogenate, etc.), aldehyde ammonias (e.g. acetaldehyde ammonia, hexamethylenetetramine, etc.), aldehyde amines (e.g. n-butylaldehydeanilline, butylaldehydemonobutylamine, etc.), and thioureas (e.g. diethylthiourea, trimethylthiourea, etc.). These 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.
On the other hand, rather than the vulcanization accelerators, 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.
If a stiffener is used, 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.
Any suitable lubricant can be used, stearic acid and esters thereof are particularly suitable. 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. For example the EPDM1 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.
When the foam of EPDM of the present invention is 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 present invention is illustrated but not limited by reference to the accompanying example.
The following formulation was prepared.
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 800C to 1000C. The heated formulation then passed to the injection chamber of the machine which was held at a temperature in the range 800C to 1200C. The formulation was then injected from the injection chamber into a cylindrical mould which was held at 1900C1 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.

Claims

1. An ethylene propylene diene formulation suitable for the production of foams by injection moulding comprising
i) solid ethylene propylene diene copolymer ii) a liquid ethylene propylene diene copolymer iii) a compatibilizer iv) a blowing agent and v) a curative system.
2. A formulation according to Claim 1 which the compatibilizer is a polyethylene wax with a melting point in the range 900C to 1100C.
3. A formulation according to Claim 1 or Claim 2 containing from 10 to 30 parts of compatibilizer per 100 parts of total ethylene propylene diene copolymer.
4. A formulation according to any of the preceding claims wherein the diene is selected from butadiene, 5-ethylidene-2-norbomene, 1 ,4-hexadiene, and dicyclopentadiene.
5. A formulation according to any of the preceding claims in which the blowing agent is an organic blowing agent.
6. A formulation according to Claim 5 containing from 0.1-40 parts by weight, preferably 5-30 parts by weight of blowing agent per 100 parts by weight of EPDM.
7. A formulation according to any of the preceding claims in which the blowing agent is an inorganic blowing agent.
8. A formulation according to Claim 7 in which the mixing ratio of the inorganic foaming agent to EPDM is in the range of 2-40 parts by weight, preferably 2- 20 parts by weight, per 100 parts by weight of EPDM.
9. A formulation according to any of the preceding claims in which a mixture of organic and inorganic blowing agent is used.
10. A formulation according to Claim 9 in which the ratio of the organic foaming agent to the inorganic foaming agent is in the range of 20/1 to 0.1/1 , preferably 9/1 to 1/1 , more preferably 6/1 to 1/1 , by weight.
11. A formulation according to any of the preceding claims containing a blowing agent activator.
12. A formulation according to Claim 11 in which the blowing agent activator is present in an amount from 2-40 parts by weight preferably 5-10 parts by weight, per 100 parts by weight EPDM.
13. A formulation according to any of the preceding claims further containing materials selected from fillers, softeners, and vulcanization accelerators, stiffeners, lubricants, plasticizers, antioxidants, pigments, colorants, fungicides, and flame retardants.
14. A formulation according to Claim 13 in which the filler comprises an inorganic fillers, selected from 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.
15. A formulation according to Claim 13 or Claim 14 in which the ratio of the filler to EPDM is 300 parts by weight or less, preferably 200 parts by weight or less, per 100 parts by weight of EPDM1 preferably from 100 parts to 200 parts by weight of filler per 100 parts by weight of total EPDM.
16. A formulation according to any of the preceding claims containing a softener in the range of 20-300 parts by weight, preferably 50-200 parts more preferably 50-100 parts by weight, per 100 parts by weight of EPDM.
17. A formulation according to any of the preceding claims in which the curative system comprises a vulcanizing agent that may be used.
18. A formulation according to Claim 17 in which the vulcanizing agent is selected . from sulfur, sulfur compounds (e.g. 4,4'-dithiomorpholine)1 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).
19. A formulation according to Claim 17 or Claim 18 in which the vulcanizing agent is used in the range of 0.1-10 parts by weight, preferably 0.5-3 parts by weight, per 100 parts by weight of EPDM.
20. A formulation according to any of Claims 17 to 19 further containing a vulcanization accelerator.
21. A formulation according to Claim 20 in which the ratio of the vulcanization accelerator to EPDM is in the range of 0.5-10 parts by weight, preferably 1-5 parts by weight, per 100 parts by weight of EPDM.
22. A formulation according to Claim 20 or Claim 22 in which the vulcanizing accelerator is zinc oxide.
23. A formulation according to any one of the preceding claims further containing a stiffener.
24. A formulation according to Claim 23 in which the stiffener is carbon black.
25. A formulation according to Claim 23 or Claim 24 in which the mixing ratio of the stiffener to EPDM is the range of 0.1-80 parts by weight, preferably 0.5-50 parts by weight, per 100 parts by weight of EPDM.
26. A formulation according to any of the preceding claims containing a lubricant.
27. A formulation according to Claim 26 in which the lubricant is as stearic acid or an ester thereof.
28. A process comprising injection moulding a formulation according to any of the preceding claims.
29. A process according to Claim 28 in which the barrel of the injection moulding machine is held at a temperature in the range 800C to 1000C and the injection chamber is held at a temperature in the range 8O0C to 1200C and the mould is at a temperature of 1300C to 2500C.
EP08715890A 2007-02-20 2008-02-20 Injection mouldable foamable ethylene propylene diene copolymer rubber formulations Withdrawn EP2115049A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0703248A GB0703248D0 (en) 2007-02-20 2007-02-20 Injection mouldable foamable ethylene propylene diene copolymer rubber formulations
PCT/EP2008/001319 WO2008101685A1 (en) 2007-02-20 2008-02-20 Injection mouldable foamable ethylene propylene diene copolymer rubber formulations

Publications (1)

Publication Number Publication Date
EP2115049A1 true EP2115049A1 (en) 2009-11-11

Family

ID=37908929

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08715890A Withdrawn EP2115049A1 (en) 2007-02-20 2008-02-20 Injection mouldable foamable ethylene propylene diene copolymer rubber formulations

Country Status (3)

Country Link
EP (1) EP2115049A1 (en)
GB (1) GB0703248D0 (en)
WO (1) WO2008101685A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6690107B2 (en) * 2015-01-09 2020-04-28 株式会社ブリヂストン Rubber composition and tire using the same

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3480265B2 (en) * 1996-11-20 2003-12-15 豊田合成株式会社 Foam rubber compound
US20050054754A1 (en) * 2003-09-09 2005-03-10 Chung-Shan Institute Of Science & Technology Rocket motor insulation containing coated hydrophilic fillers

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2008101685A1 *

Also Published As

Publication number Publication date
GB0703248D0 (en) 2007-03-28
WO2008101685A1 (en) 2008-08-28

Similar Documents

Publication Publication Date Title
EP1683827B1 (en) Open-cell foam of ethylene-propylene-diene rubber
US7989515B2 (en) Filling foam composition, foam filling member, and filling foam
US20030050352A1 (en) Foamed Polymer System employing blowing agent performance enhancer
JP4993470B2 (en) Ethylene / propylene / diene rubber foam
CN103502338B (en) Foam composition for filling/sealing purposes, foam member for filling/sealing purposes, and foam body for filling/sealing purposes
CN102731815B (en) Filling foam composition, foam filling member, and filling foam
JP2004143262A (en) Thermal expansion material, method for producing the same, and soundproof sheet for automobile
CN102206423A (en) Foaming composition for filling, foaming member for filling and foam for filling
EP2115049A1 (en) Injection mouldable foamable ethylene propylene diene copolymer rubber formulations
JP3588291B2 (en) Rubber-based foam material and foam thereof
CN101293973B (en) Filling foam composition, foam filling member, and filling foam
JP4150467B2 (en) Rubber-based foam material and foamed body thereof
CN100398590C (en) Filling and foaming composition, filling and foaming member, and filling foam
JP2021004323A (en) Ethylene propylene diene rubber foam, and its manufacturing method
JP3833381B2 (en) Foam curable composition and foam
WO2005049706A1 (en) Resin composition for foam molding, foam, and process for producing foam
JP2001288292A (en) Rubber-based flame-retardant foam composition and its foam
JP2003171490A (en) Rubber foam for sealing
JPH10330560A (en) Resin composition for expansion molding and expansion-molded product
JP2002128932A (en) Rubber flame retardant foam
JP2002146072A (en) Rubber-based vulcanized foam composition and foam thereof
JP3758116B2 (en) Open cell foam and method for producing the same
JPH0395238A (en) Foam
JP2004244508A (en) Reinforcement composition, reinforcement, vehicle body reinforcement method and vehicle body reinforcement structure
JP2003171489A (en) Rubber foam for sealing

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20090915

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR

DAX Request for extension of the european patent (deleted)
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20150901