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
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
• • 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
  • C08J2353/00—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
  • C08J2353/02—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers of vinyl aromatic monomers and conjugated dienes
• • 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
  • C08J2421/00—Characterised by the use of unspecified rubbers

Definitions

• the invention relates to a cross-linked foamed composition and to a process for the preparation thereof.
• the foamed natural and synthetic rubber substances obtained by this cross- linking method are unsatisfactory in that they have a low degree of l ⁇ foam expansion and poor cushioning and gas permeability properties. It is an object of the present invention to provide a cross-linked foamed composition which has a high degree of foam expansion, a light weight, good cushioning, gas permeability and sound proofing properties. no Accordingly, the invention provides a cross-linked foamed composition, characterized in that it is prepared by cross-linking and foaming in a heat medium of a starting mixture comprising the following components: -
• the invention further provides a process for the manufacture of a cross-linked foamed composition which process comprises blending the following components:- component (1) in the range of from 20 to 100% by weight of a block copolymer of an aromatic vinyl compound and/or a 5 selectively hydrogenated product thereof and component (2) in the range of from 0 to 80% by weight of one or more rubbers selected from natural rubber, diene type synthetic rubber and non-diene type synthetic rubber, 0 the sum of said percentages being 100, and, calculated on 100 parts by weight of [(l)+(2)], component (3) in the range of from 0 to 300 parts by weight of a softener, component (4) in the range of from 0 to 600 parts by weight of an 25 inorganic filler, component (5) in the range of from 3 to 60 parts by weight of a blowing agent, and component (6) in the range of from 0.1 to 10 parts by weight of a cross-linking agent, op and cross
• the aromatic vinyl-conjugated diene block copolymer or aromatic vinyl-hydrogenated conjugated diene block copolymer (1) used in the present invention is thermoplastic and may be a block or copolymer represented by the following formula (A-B) A , (A-B) or ⁇ (A-B) ) C n n n m
• A represents an aromatic vinyl compound polymer
• B represents a conjugated diene polymer or copolymer or a hydrogenated polymer of a conjugated diene polymer or copolymer
• C represents a coupling agent residue.
• the aromatic vinyl compound (A) is suitably present in a quantity in the range of from 7% to 90%, preferably of from 10% to 70%, and its molecular weight lies between 10,000 and 1,000,000, more preferably between 70,000 and 300,000, so that an even more excellent foamed composition according to the present invention is obtained.
• component mixture [(l)+(2)] component
• (1) is present in an amount in the range of from 20 to 100% by weight, preferably 40-90% by weight, since with less than 20% by weight it is difficult to obtain a foamed substance with a great expansion rate.
• exemplary aromatic vinyl compounds are styrene, alpha- methylstyrene, ortho-, meta- and para-methylstyrene, o-, m- and p-ethylstyrene, o- , m- and p-methoxystyrene, dimethylaminostyrene, o-, m- and p-isopropylstyrene, p-t-butylstyrene.
• styrene para-methylstyrene and alpha-methylstyrene are preferred.
• polymers a polymer of only one, or a block or random copolymer composed of two or more of these monomers may be used.
• content of the aromatic vinyl compound present it differs with the molecular weight and the use envisaged, but suitably it lies between 7% and 90%, preferably between 10% and 70% and more preferably 10% and 50%.
• conjugated diene polymer or copolymer or the hydro ⁇ genated polymer of a conjugated diene polymer or copolymer a single butadiene, isoprene, piperylene polymer, or a block or a random copolymer composed of two or more thereof, or a copolymer in which the arrangement of the aromatic vinyl compound part is random or tapered, and hydrogenated polymers of these conjugated diene polymer may be used.
• styrene as the aromatic vinyl compound and butadiene and/or iosprene as the conjugated diene compound.
• natural rubber, diene-type synthetic rubber, non-diene-type rubber are used in a range of 0 to 80% by weight, preferably of 10-60% by weight, mainly to control the elasticity and the cross-linking speed of the foamed substance.
• NR natural rubber
• diene-type rubbers such as polyisoprene rubber (IR) , styrene-butadiene rubber (SBR) , polybutadiene rubber (BR) , poly(l,2-butadiene) rubber (RB) , acrylonitrile rubber (NBR) , chloroprene rubber (CR) and non-diene-type rubbers, such as ethylene-propylene rubber (EPM) , ethylene-propylene-terpolymer (EPDM) , ethylene-vinyl acetate copolymer (EDA), acrylic rubber (ACM, ANM) , fluorine rubbers.
• EPM ethylene-propylene rubber
• EPDM ethylene-propylene-terpolymer
• EDA ethylene-vinyl acetate copolymer
• ACM acrylic rubber
• ANM fluorine rubbers.
• the softener used as component (3) in the present invention may be an aromatic, naphthenic or paraffinic process oil, petroleum-based asphalts, such as street asphalt, blown asphalt, petroleum-based softeners, such as lubricating oil, solid paraffins, liquid paraffins, vaseline; coal tar sof eners, such as coal tar, coal tar pitch, resinous oil softeners, such as castor oil, linseed oil, rape seed oil, coconut oil; waxes, such as bees wax, carnauba wax, lanolin; tolu oil and factice.
• petroleum-based asphalts such as street asphalt, blown asphalt
• petroleum-based softeners such as lubricating oil, solid paraffins, liquid paraffins, vaseline
• coal tar sof eners such as coal tar, coal tar pitch
• resinous oil softeners such as castor oil, linseed oil, rape seed oil, coconut oil
• waxes such as bees wax, car
• Suitable softeners are process oil, petroleum asphalt; preferably a process oil and a petroleum asphalt are used simultaneously. When a process oil and a petroleum asphalt are used simultaneously, foaming during cross-linking is the same as when a process oil is used alone, while the foamed composition will have a higher degree of hardness.
• the softener component (3) is present in a quantity in the range of from 0 to 300 parts by weight, preferably 50 to 150 parts by weight on 100 parts by weight of components [(l)+(2)]. When more than 300 parts by weight is present, there is a great risk of softener bleed and handling becomes difficult.
• the inorganic filler used as component (4) in the present invention may be for instance light calcium carbonate, heavy calcium carbonate, various kinds of surface treated calcium carbonates, and talc, magnesium hydroxide, mica, clay, barium sulphate, natural silicic acids, synthetic silicic acids (white carbon) , titania and various carbon blacks.
• heavy calcium carbonate is preferred for its economic advantages.
• the quantity of inorganic filler used is in the range of from 0 to 600 parts by weight, preferably 0 to 400 parts by weight, calculated on 100 parts by weight of components [(l)+(2)]. When more than 600 parts by weight is blended in, it will be hard to obtain a high degree of foaming and the mechanical strength of the foamed material obtained will be quite poor.
• the blowing agent used in the present invention as component (5) may be a well known inorganic or organic blowing agent. These may also be used simultaneously.
• blowing agents are sodium bicarbonate, aluminium bicarbonate, sodium carbonate, aluminium carbonate, azodicarbonamide (ADCA) , dinitrosopenta- methylenetetramine (DNPT) , dinitrosoterephthalamide, azobisisobutyro nitrile, azodicarboxylic acid barium, sulphonyl hydrazide, toluenesulphonyl hydrazide.
• ADCA azodicarbonamide
• DNPT dinitrosopenta- methylenetetramine
• DNPT dinitrosoterephthalamide
• azobisisobutyro nitrile azodicarboxylic acid barium
• sulphonyl hydrazide toluenesulphonyl hydrazide.
• the amount of blowing agent used is in the range of from 3 to 60 parts by weight, preferably 5 to 40 parts by weight on 100 parts by weight of components [(l
• the foamed composition obtained When less than 3 parts by weight of blowing agent is used, the foamed composition obtained will have a low foam expansion rate and when more than 60 parts by weight is present, the amount of gas formed by the decomposition of the blowing agent will become too large and the external appearance of the foamed product will be poor.
• a cross-linking agent is added in addition to the afore-mentioned ingredients to form the foam substance.
• cross-linking agents energy such as electron rays, ultra violet rays may also be used as cross-linking and blowing aids.
• cross-linking agents sulphur and various kind of organic peroxides may be mentioned.
• Exemplary organic peroxides are dicumyl peroxide, 1,1-bis(t-butyl- peroxy)-3,3,5- rimethylcyclohexane, t-butylperoxybenzoate, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butyl peroxy- isopropylcarbonate.
• the cross-linking agent is suitably present in an amount in the range of from 0.5 to 5% by weight, calculated on 100 parts by weight of the sum of components (1) and (2) .
• vulcanization accelerators may be added simultaneously to carry out the cross-linking and blowing.
• exemplary vulcanization accelerators are dibenzothiazyldisulphide (MBTS) , 2-mercaptobenzothiazole (MBT) , N-cyclohexyl-2-benzothiazyl-sulphenamide (CBS) , N-oxyzoethylene- 2-benzothiazyl-sulphenamide (DBS) , tetramethylthiurea disulphide (TMTD) , tetramethylthiurea monosulphide (TMTM) .
• MBTS dibenzothiazyldisulphide
• MBT 2-mercaptobenzothiazole
• CBS N-cyclohexyl-2-benzothiazyl-sulphenamide
• DBS N-oxyzoethylene- 2-benzothiazyl-sulphenamide
• TMTD tetramethylthiurea disulphide
• TMTM tetra
• the surface is softened by decomposition due to oxidation of the surface of the cross-linked product.
• the surface of the blend (the area that is in contact with the hot air) can be covered with a thin polyester film, or a thin sheet of a rubber compound which does not blend with the cross-linking agent, so that decomposition by oxidation in hot air cross-linking will be stopped and a good cross-linked foamed substance can be obtained.
• sulphur vulcanization is more desirable than cross-linking with an organic peroxide.
• additives such as cross-linking aids, anti-ageing agents, processing aids, plasticizers and tackifiers may suitably be added as required.
• the method of mixing the afore-mentioned components (l)-(5) and further compounding ingredients there are no specific restrictions as to the method of mixing the afore-mentioned components (l)-(5) and further compounding ingredients; the usual mixing methods for preparing rubber blends, such as the Banbury mixer, pressure kneader, open roll may be applied.
• the non-cross-linked product obtained is shaped as required into, for instance, sheets, it is subjected to cross-linking and foaming in a heat medium.
• Cross-linking and foaming is carried out in hot air of a temperature in the range of from 100 to 200 °C, preferably 120 to 170 °C, and as the temperature rises above the decomposition temperature of the blowing agent, the blend is cross-linked and the blowing agent decomposes.
• the cross-linking and foaming can be carried out at atmospheric pressure.
• the heat medium used in the present invention may be a gas, such as air or nitrogen, hot fluids, hot solids, such as hot dust and hot fine granules.
• a hot gas is preferred, and hot air in particular.
• the cross-linking and foaming may De carried out on top of a hot metal plate.
• the cross-linking and foaming operations can be performed batch-wise or continuously.
• the cross-linked and foamed substance of the present invention has a high degree of foam expansion, is light-weight and has very good cushioning, gas permeability and sound proofing properties.
• the cross-linked and foamed substance of the present invention may be put to a wide range of uses, e.g. as material for foot wear, industrial articles, as shock absorbing material, sealing material, lining material, such as sound proofing and sound absorbing material, insulating material, carpeting and for metal plate laminating.
• tensile strength and tension pull were determined by the JIS K-6301 method, hardness 5 with the rubber test type C (sponge hardness meter, type Macro- molecular Gauge) , specific gravity with the floating method and the foam expansion rate by comparing the thickness of samples taken before and after foaming.
• Example 1 100 pbw of a styrene-butadiene block copolymer (40% by weight bonded styrene) (ex Japan Synthetic Rubber, JSR TR 2000) and further ingredients were mixed in a BR type Banbury mixer in proportions as listed in Table 1 and rolled into 2 mm thick sheeting with the aid of a 25.4 cm test roller to form a ic non-cross-linked sheet, which was cross-linked and foamed for 25 minutes in hot air at a temperature of 145 "C to obtain a foamed substance.
• the resulting properties are listed in Table 1. Examples 2-4
• Foamed substances were prepared in the same way as in Example 1, except that 100 pbw of a styrene-butadiene block copolymer (60%
• Foamed substances were prepared in the same way as in Example 1, except that 100 pbw of a styrene-isoprene block copolymer (15% by weight bonded styrene) (ex Japan Synthetic Rubber, JSR SIS 5000) and 70 pbw of a styrene-butadiene block copolymer (15% by weight bonded styrene) (JSR SIS 5000), respectively, and 30 pbw 1,2-polybutadiene (JSR RB 820) were used.
• JSR SIS 5000 Japanese Synthetic Rubber
• JSR SIS 5000 styrene-butadiene block copolymer
• JSR RB 820 30 pbw 1,2-polybutadiene
• Example 9 A foamed substance was prepared under the same conditions as in Example 1, starting from 70 pbw of a styrene-butadiene block copolymer (40% by weight bonded styrene) (ex Japan Synthetic Rubber, JSR TR 2000) and 30 pbw of natural rubber and using the blends listed in Table 1. The resulting properties are listed in Table 1.
• Foamed substances were prepared in the same way as in Example 1 but using the polymers in proportions outside the scope of the present invention. 85 pbw of natural rubber was used with 15 pbw of a styrene-butadiene block copolymer (40% by weight bonded styrene) (JSR TR 2000) and 15 pbw of a styrene-butadiene block copolymer (60% by weight bonded styrene) (JSR TR 2400). The resulting properties are listed in Table 2.
• Comparative Experiment C A foamed substance was prepared in the same way as in Example 1 but using 100 pbw styrene-butadiene rubber (ex Japan Synthetic Rubber, JSR 1507 which is a random polymer) as the polymer. The results are shown in Table 2. Comparative Experiment D A foamed substance was prepared in the same way as in Example 1 but using 100 pbw natural rubber as the polymer. The resulting properties are listed in Table 2.
• the ingredients for the cross-linked and foamed substance according to the present invention viz. a block copolymer of an aromatic vinyl compound and a conjugated diene compound and a specified kind of rubber are blended in proportions lying within a specified range and cross-linked and foamed in a heat medium such as hot air to prepare a product of unprecedentedly good properties. Since its foam expansion rate is high it is very light weight, and therefore it can be expected to have very good cushioning, gas permeability and sound proofing qualities, and it can be suitably used as material for foot wear, industrial articles, as shock absorbing material, sealing material, lining material, sound proofing and sound absorbing material, insulating material and carpeting.

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• 1988
  • 1988-01-08 WO PCT/EP1988/000014 patent/WO1989006255A1/en not_active Ceased
  • 1988-01-08 BR BR888807404A patent/BR8807404A/pt unknown
  • 1988-01-08 EP EP19880901032 patent/EP0347413A1/de active Pending

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