IL44452A

IL44452A - Light-weight rubber products and their manufacture

Info

Publication number: IL44452A
Application number: IL44452A
Authority: IL
Original assignee: Aharon Pacholder
Priority date: 1974-03-20
Filing date: 1974-03-20
Publication date: 1977-10-31
Also published as: IL44452A0

Description

products and their manufaoture This invention relates to rubber articles and processes for their A large variety of fillers have been used in the rubber their purpose being to reduce the cost of the products to impart to them special One of the known fillers is ground cork which has been used to obtain products of relatively low and such products have found inter in certain parts of and heels for shoes and It has now been in accordance with the present that rubber products having improved properties can be obtained at a considerably lower by replacing all or part of the in the aforesaid rubber with a foamed polymeric material in particulate The present invention thus provides a rubber article comprising from about 3 to about by weight of a particulate foamed polystyrene distributed therein additional fillers The term is used herein to include both natural rubber and synthetic elastomers which have been vulcanized by any of the known vulcanization as contrasted to which will be used herein to denote such a natural rubber or synthetic elastomer in the unvulcanized state or in a The term will be used herein to include any of the commercially available forms of concentrated natural synthetic latex or a mixture of the The rubber articles according to the invention quite different in their physical of and from the disclosed in Israel Patent Specification Those known resilient are composed of a set rubber latex foam and a set polyurethane each foam having its ow individual continuous lattice In accordance these known materials are produced by causing a liquid rubber latex composition to expand as a foam through the interstices of a separately set polyurethane foam lattice This is in full contrast with the process according to the present as described particulate polyme the articles according to the invention pre erably have average particle size of about about 50mm in most preferably from about 1 to 3 particles of suitable size can be compounding with raw rubber or with as and such particles are or may obtained by milling foamed scrap raw rubber or latex may be compounded with beads or pellets of unfoamed polymer containing the necessary amount a Blowing agent h as are available these are foamed o expanded the course the vulcanization as hereinafte A foamed polymer for the rubber according to the is polystyrene or foamable beads of polystyrene a blowing agent which ar unde the The foamed polymer should have a density of from about 10 to about 100 preferably from about 10 to about 0 For certain applications of the rubber articles according to the invention they advantageously to contain on mor additiona for soles soles or it was found that for the production insoles for shoes and excellent results were obtained when ground was incorporate in the rubber in addition to the foamed in a of cork to polymer of about to by lightweight rubber articles according the invention are produced by by a conventional the required amount of raw rubber or latex with the required amount of particulate foamed or with foamable particles of the polyme containing the blowing with the required amount of one or mor conventional vulcanizing agents and and optionally with additional fillers trans erring the mixture thus mould of suitable and vulcanizing the mixture at a predetermined temperature and pressure until the vulcanisation is The formed article is then removed from the if further submitted to drying A process as described above in late is is inter because of the relativ ease of the compounding operation and the comparatively lower temperatures required for the vulcanization Both the aforesaid features permit the with latex as starting of such kinds grades of foamed polymer as are sensitive to the greater stresses applied course of compounding raw rubber and the higher temperatures longer times which as a neceesary vulcanizing raw In a typical process according to the say fo the production of by volume of concentrated natural latex about 60 raw is mixed in a conventional industrial with 5 parts by volume of foamed polystyrene having average diameter of 1 mm and a density of 12 in presence of a suitable The usual amounts of known insufficientOCRQuality

Claims

9 •44452/2 CLAIMS:

1. A light-weight rubber article comprising from about 3 to about 60 percent by weight of a particulate foamed polystyrene filler, distributed therein and, optionally, additional fillers and/or additives.

2. A rubber article according to Claim 1, wherein the particles of the foamed polystyrene have an average diameter of about 0.5 to 50 mm, preferably about 1 to 3 mm.

3. A rubber article according to Claim 1 or 2 which additionally comprises ground cork, distributed therein.

4. A rubber article according to Claim 3, wherein the proportion of the cork to the foamed polystyrene is from about 1:10 to about 50:1 by weight.

5. A rubber article according to any one of Claims 1 to 4, which additionally includes reinforcement, e.g. fibers or a fabric.

6. A rubber article according to any one of Claims 1 to 5 for use as a part of footwear.

7. A rubber article according to Claim 6 for use as a sole, middle sole or an insole, particularly an orthopaedic ("foot-form") insole.

8. A rubber article according to Claim 6 for use as a heel.

9. A process for producing light-weight rubber articles according to any one of Claims 1 to 8, which comprises mixing latex with particulate foamed polystyrene, one or more vulcanization aids and, optionally additional fillers and/or additives, and submitting the mixture to vulcanization in moulds at an elevated temperature and -10- ' 44452/2

10. A process for producing light-weight rubber articles according to any one of Claims 1 to 8, which comprises mixing raw rubber or latex with beads of a foamable polystyrene containing a blowing agent, and with one or more vulcanization aids and, optionally, additional fillers and/or additives, and submitting the mixture to simultaneous vulcanization of the rubber and expansion of the polystyrene at an elevated temperature and under elevated pressure.

11. A process according to Claim 9 or 10, wherein ground cork is used as an additional filler.

12. A process according to Claim 11, wherein the proportion of the cork to the foamed polystyrene is from about 1:10 to about 50:1.

13. A process according to any one of Claims 9 to 12, wherein a reinforcement is incorporated in the article before the mixture is vulcanized.

14. A process according to any one of Claims 9 to 13, wherein a part of footwear is produced.

15. A process according to Claim 14, wherein a sole, middle sole or an insole is produced. For the Ap&^icant