USRE18691E - Necticut - Google Patents

Description

Reisauecl Dec. 13, 1932 UNITED STATES PATENT OFFICE WILLIS A. GIIBBONS, OF MONTCTLAIR, NEW JERSEY, ASSIGNOR TO THE NAUGATUCK CHEMICAL COMPANY, OF NA'UGATUCK, CONNECTICUT, A CORPORATION OF CON- NECTICUT' PROCESS FOR MODIFYING VULCANIZABLE MATERIAL AND PRODUCT No Drawing. Original No. 1,807,031, dated May 26, 1931, Serial No. 174,716, filed March 11, 1927.

Application for reissue filed March 30, 1932. Serial No. 602,104.

This invention relates to a process for modifyin r vulcanizable material and to the product thereof more particularly to a process for modifying the physical properties of the material and its product.

In the manufacture of rubber articles the raw rubber used comes from many sources, is obtained from the latex in various ways and is variously treated to adapt it for different uses. For instance there are plantation rubbers obtained from the latex by different c0- agulation methods in which all or a greater part of the soluble contents of the latex have been eliminated, wild rubbers from which a greater or less part of the soluble constituents of the latex have been removed, and all-solidcontent latex rubbers obtained by the direct drying of latex. Aside from cleaning operations where necessary, the usual preliminary step is to break down the crude rubber on heated rolls, after which it may be compounded and used in plastic form or treated with organic solvents for spreading or dipping operations. Recently there has been considerable use of latex direct for spreading, dipping and similar purposes. The various rubbers as obtained from the latex vary considerably in their properties, such as break down period, ageing, elasticity, tensile strength, viscosity, softness, optimum curing time, etc., and as a result one of them may be most suitable for a certain use while another is best adapted for some other purposes. For instance the all-solid content latex rubber has great strength, superior ageing and curing qualities and elasticity, but ordinarily requires a longer breakdown period than certain other rubbers. It will therefore be seen that it is often desirable to impart to one variety of crude rubber properties possessed by another while at the same time retaining certain of its own distinguishing characteristics. It is obvious that by so modifying the properties of one rubber stock it may be made to serve for a greater number of purposes, with resulting increased efiiciency and economy. It has also been found that articles or materials obtained by direct deposition of rubber from latex, as by spreading or dipping, even when vulcanized are stiffer or more inflexible modifying the milling properties of crude rubber.

Still another object is to provide a process for modifying the physical properties of vulcanizable or vulcanized articles or materials, pbtained by direct deposition of rubber from atex.

A further object is to increase the fieldof usefulness of individual crude rubbers in'the rubber art.

A still further object is to provide a crude rubber having a reduced break down period.

A still further object is to provide a vulcanizable or vulcanized material, derived directly from latex, and having an increased flexibility.

The invention consistsbroadly in modifying the properties of vulcaniz able material, particularly its physical properties, by preliminarily subjecting latex to regulated heat and pressure, with or without the assistance of chemicals, and it also consists in the product of the process.

For a detailed disclosure of the invention reference is had to the accompanying specification.

In carrying out one embodiment of the invention in the case of a vulcanizable material such as rubber, rubber latex is disposed in a closed vessel or tank in quantity suflicient almost to fill the same, and is then subjected to heat, and to pressure such as that resulting from the heating. This heating may be accomplished in any suitable manner, as by using a steam jacketed tank. The heat may be applied in gradually increasing degree for a definite period, or after such gradual heatcrepe is shown in the following data taken from a series of tests:

' Break Power Heating conditions [or preliminarily treated. down conall-solids content-latex rubber time sitrmpion Kilowatt l M'imztes h'our hr. rise to 20# steam 7% 0958 $5 hr. rise to 201! 1 hr. at 20# 6 0696 hr. rise to 20# 1 hr. at 20# 8 .0895 6 hr. rise to 60;! 7 .0841 6 0695 56 hr. rise to 60# 1 hr. at 60#- 6% 0722 )6 hr. rise to 60# 3 hrs. at 60# l. 5 Ordinary all-solids content latex rubber 10-11 1308 Pale crepe .7 7% 0977 The latex rubbers referred-to in the above table were obtained by spray drying of the latex, but the invention is not, however, limited to rubber obtained from the latex by any particular method. It is known'to sterilize latex at 212 F. under pressure. Such procedure, however, is a brief one and it will :be apparent from the above table that the treatment in this case is in excess of such a treatment in order to have the desired effect upon the rubber rather thanon the germs present in the latex. V o

In addition to the heat treatment above described the'process may also include the use as for example derivatives of hydroxylamins.

or hydrazines. The invention also includes treating latex with substances adapted to alter the properties of the rubber hydrocarbon either chemically or physically, but excluding vulcanization, as for example rubber solvents or softeners or substances adapted to oxidize rubber, such as drying oils and/or oxidizing agents. These materials may if desired be added to the latex in the form of emu sions.

The preliminarily treated latex may be used directly for such operations as dipping or spreading, and it has been found that the material or articles formedin this manner have a greatly increased flexibility, whileat the same time retaining all the desirable-qualities obtained by the use of untreated latex. If desired the preliminarily treated latex may be concentrated in the usual manner, and the concentrated latex used as desired with the same good results as obtained in the case of unconcentrated treated latex. The treated latex may also be converted into crude rubber by any of the standard methods, which rubber has been-found to be considerably softer and to have a shorter breakdown period. The treated latex may be sprayed directly from the vessel in which it has been heated under pressure. By running the latex while still hot into the spray chamber the heat content of the latex may thus be utilized and an economy in manufacture effected. It might be supposed from previous knowledge of the characteristics of rubber that the above described treatment for increasing the softness and reducing the breakdown period of the rubber would result in a corresponding decrease in the tensile strength and deterioration in its other physical properties, but such has not been found to be the case. For in stance the time of cure and the tensile strength of spray dried rubber, produced from the heat treated latex has been found to be practically the same as, and in some cases superior to, that produced from spray dried unheated latex. a

. It will'be seen that by my invention the field of use for an individual crude rubber maybe considerably enlarged by modifying its properties to adapt it for purposes for which another rubber stock may have been primarily more suitable, thus enabling rubber factories to reduce the number of different stocks required for various purposes. In particular the reduction in the breakdown period from the normal one required with a similar rubber made from untreated latex constitutes a valuable saving both in the time, labor and space required, and also in the power consumption. The increased flexibility of goods obtained by the direct deposition of rubber from the treated latex is also another valuable feature of the invention. I

While the invention has been more or less specifically described it is obvious that the present disclosure will suggest numerous modifications to those skilled in the art and it is not desired to limit the invention otherwise than as set forth in the appended claims.

. Having thus described my invention, what I claim and desire to protect by Letters Patent is: v

1. The process of modifying the properties of vulcanizable material by preliminary treatment'of latex with normal water content which. process comprises heating the latex above 212 F. without evaporation of its water content for a length of time in excess of that required to sterilize latex against the action of bacteria.

2. The process of modifying the properties of vulcanizable material by preliminary treatment of normal latex which comprises gradually raising the temperature of the latex to a. predetermined point above 212 F. while contained in a closed vessel, and maintaining it at such point for about one-half to three hours.

3. The process of modifying the milling properties of vulcanizable material which consists in subjecting latex of normal water content to a regulated heat and pressure at a temperature above 212 F. for at least a half hour while simultaneously maintaining its water content substantially unchanged, and subsequently withdrawing water therefrom.

4. The process of modifying the physical properties of vulcanizable material by preliminary treatment of normal latex which comprises subjecting the latex without coagulation, precipitation to its solids or substantial change in its water content, to the action of chemicals under gradually increasing heatand pressure to above 212 F. for a length of time in excess of that required to sterilize latex against the action of bacteria.

5. A method of treating an aqueous dispersion of rubber comprising subjecting a rubber latex in the absence of vulcanizing agents to an elevated temperature without substantial evaporation of the water content for a length of time in excess of that required to sterilize latex at such temperature against the action of bacteria.

6. A method of treating an aqueous disper sion of rubber comprising subjecting a rubber latex in the absence of vulcanizing agents to a. temperature above 212 F. for at least a half hour without substantial evaporation of the water content.

7. A method of treating an aqueous dispersion of rubber comprising subjecting a rubber latex in the absence of vulcanizing agents to a temperature above 212 F. for a length of time in excess of that required to sterilize latex against the action of bacteria. v

8. A method of treating an aqueous dispersion of rubber comprising subjecting a rubber latex treated with a non-vulcanizing modifying reagent to an elevated temperature with out substantial evaporation of the water content thereof for a period of time sutficient to permit the conversion of water-in soluble nonrubber constituents into water-soluble prodnets.

9. A method of treating an aqueous dispersion of rubber comprising subjecting a rubber latex in the presence of a substance adapted to combine with or decompose a non-rubber constituent of the latex to a. temperature above 212 F. for a length of time in excess of that required to sterilize latex against the action of bacteria Without substantial evaporation of the water content thereof.

10. A method of treating an aqueous dispersion of rubber comprising heating at an elevated temperature fora period oftime in excess of that required to sterilize latex against the action of bacteria at such temperature, a rub-ber latex in the presence of a substance adapted to decompose proteins in" the latex and without substantial reduction of the water content thereof.

11. A method of treating an a ueous dispersion of rubber comprising su jecting a rubber latex in the presence of caustic alkali to a temperature above 212 F. for at least a half hour without substantial evaporation of the water content.

12. The process of modifying the properties of vulcanizable material which comprises subjecting a rubber latex treated with a nonvulcanizing modifying reagent to an elevated temperature for a period of time sufficient to permit the conversion of water-insoluble non-rubber constituents into watersolub-le products and subsequently recovering rubber from the thus treated latex.

13. The process of modifying the properties of vulcanizable material which comprises subjecting a rubber latex in the presence of a substance adapted to decompose a non-rubber constituent of the latex to an elevated temperature for a predetermined period of time without substantial decrease of the water content of the latex, and subsequently recovering rubber from the thus treated latex.

14. The process of modifying the properties of vulcanizable material which comprises subjectin a rubber latex in the presence of caustic allxali to an elevated temperature for -mo a. predetermined period of time, and subsequently recovering rubber from the thus treated latex.

15- The process of modifying the properties of vulcanizable material'which comprises subjecting a rubber latex to an elevated temperature without substantial evaporation of the water content for a length of time in excess of that required to sterilize latex against the action of bacteria at such temperature, and subsequently recovering rubber material from the thus treated latex.

16. The process of modifying the properties of vulcanizable material which comprises subjecting a rubber latex in the presence of a substance adapted to decompose a non-rubber constituent of the latex to a temperature above 212 F. for at least a half hour without substantial evaporation of the water content, and subsequently recovering rubber ma- 12o terial from the thus treated latex.

17 The process of modifying the properties of vulcanizable material which comprises heating a rubber latex above 212 F. for at least a half hour without substantial evaporation of the water content and subsequently recovering rubber material from the thus treated latex.

18. As a new article of manufacture, a rubber product obtained from modifying normal 'York, and State of New York, this 29th day latex by heat and pressure at a temperature above2l2 F. without substantial change in the water content for a length of time in excess of that required to sterilize latex against the action of bacteria.

' 19. As a new article of manufacture, a vulcanizable rubber product obtained from modifying normal latex by the action of chemicals and heat and pressure at a temperature above 212 F. for at least one-half hour, said product having increased softness and reduced viscosity. 2 p

. 20. As a new 7 article of manufacture, a modified crude rubber obtained from heating normal latex under heat and pressure at a temperature above 212 F. for one-half to three hours and having a sub-normal breakdown period and increased flexibility.

21. As. a new product, a rubber latex heated in the absence of vulcanizing agents at an elevated temperature without substantial evaporation of the water content for a length of time in excess of that required to sterilize against the action of bacteria at such elevated temperature.

22. As a new product, a rubber latex heated in the absence of vulcanizing agents above 212 F. for at least a half hour without substantial evaporation of the water content;

23. As a new article of manufacture, a rubber product obtained from a latex treated with a non-vulcanizing modifying reagent, and subjected to a temperature above 212 F. for at least a half hour without substantial evaporation of the water content.

'24. As a new product, a rubber latex heated in the absence of vulcanizing agents above 212 F. without substantial evaporation of the water content for a length of time in excess of that required to sterilize latex against the action of bacteria.

25; As a new article of manufacture, a rubber product obtained from heating a latex at a temperature above 212 F. for a length of time in excess of that required to sterilize latex against the action of bacteria without substantial change in the water content thereof. i

Signed at New York, in the county of New of March, 1932.

WILLIS A. GIBBONS.