Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/02—Copolymers with acrylonitrile
  • C08L9/04—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
  • C08C19/00—Chemical modification of rubber
  • C08C19/02—Hydrogenation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/10—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L19/00—Compositions of rubbers not provided for in groups C08L7/00 - C08L17/00
  • C08L19/02—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/06—Copolymers with styrene
  • C08L9/08—Latex

Definitions

• the process disclosed by Wideman involves the hydrogenation of carbon-carbon double bonds of an unsaturated polymer which comprises (a) combining an unsaturated polymer in latex form with (1) an oxidant selected from the group consisting of oxygen, air and hydroperoxides; (2) a reducing agent selected from the group of hydrazine and hydrates thereof; and (3) a metal ion initiator; and (b) heating the mixture to a temperature from 0°C to the reflux temperature of the reaction mixture.
• crosslinking of the polymer within the individual latex particles typically occurs. This is due to concurrent crosslinking of the elastomeric polymer which occurs as a side reaction during the reduction procedure. Such crosslinking is often undesirable with it usually being preferred for the elastomeric polymer to be uncrosslinked.
• the dried rubber from the blend of rubber latices of the present invention has superior ozone resistance when compared to the dried rubber from the nonhydrogenated component of the blend and superior processing properties when compared.to the dried rubber from the hydrogenated component of the blend.
• Figure 1 is a graphic depiction of the ozone testing data of the samples of Table III.
• the present invention relates to a blend of rubber latices comprising, based on dry weight,
• nonhydrogenated latex selected from the group consisting of polybutadiene latex, natural rubber, styrene-butadiene copolymer (SBR) latex, synthetic polyisoprene latex, acrylonitrile-butadiene copolymer (NBR) latex, butadiene-isoprene copolymer latex, isoprene-isobutylene copolymer latex, styrene-isoprene-butadiene (SIBR) copolymer latex and mixtures thereof.
• the blend of latices comprise from about 70 to about 55 of the nonhydrogenated latex.
• the hydrogenated latex is a hydrogenated NBR
• an emulsion NBR as the nonhydrogenated latex.
• the solids content, also known as percent solids, of the nonhydrogenated latex may vary.
• the percent solids may range from about 5 to about 70.
• the percent solids ranges from about 10 to about 40.
• the nonhydrogenated latex is prepared in accordance with conventional emulsion polymerization techniques. The principles of emulsion polymerization are discussed in references such as "Synthetic Rubber" by G.
• free radical polymerization initiators that are used in emulsion polymerizations include compounds such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide and paramenthane hydroperoxides, and even hydrogen peroxide. These compounds perform very effectively when used in polymerization recipes containing appropriate levels of supporting ingredients.
• supporting ingredients is meant those materials often referred to as activators in emulsion, or other systems where required.
• U.S. Patent No. 3,080,334 describes some of these materials at column 5, lines 20-26. Such materials can also be referred to as catalyst activators.
• Redox Polymerization is often used where the complete initiator system includes a redox system, i.e., reducing agents and oxidizing agents in a proportion that yields polymerization initiating species. All of these initiator systems are well known in the art.
• Emulsion polymerizations are normally accomplished in the range of 5°C to 90°C. Though the activator or "redox" initiated systems are preferred for low temperature polymerizations , they are very effective at high temperatures also, normally requiring appreciably lower quantities of the various ingredients to obtain a desirable polymerization rate.
• the free radical sources used in the initiator systems are those customarily used in free radical polymerizations, for example, organic initiators such as azonitriles, azo-derivatives , peroxides and hydroperoxides and inorganic initiators such as inorganic peroxy compounds. Radiation, e.g., of the ultraviolet and gamma ray type can also be used as a free radical source.
• organic initiators are described by J. Brandrup and E. H. Immergut, Polymer Handbook (John Wiley S* Sons), 1965, .pages II-3 to 11-51.
• the pH of the nonhydrogenated latex emulsion generally ranges from about 7-5 to 13. Preferably, the pH ranges from about 8 to 11.
• the nonhydrogenated latex emulsion may also contain various conventional compounds such as surface active agents, short stop materials such as di-tertiary-butyl hydroquinone and similar compounds, all of which are present in small amounts.
• the surface active agents may consist of emulsifiers comprising the salts of natural acids such as potassium stearate, potassium-processed rosin, and the like, or such surface active agents may be synthetics such as alkali metal salts of alkyl aryl sulfonic acid, particularly alkylbenzene sulfonic acid, condensed naphthalene-formaldehyde sulfonic acid, and the like, or non-ionics such as polyalkylene oxide dioleates, sorbitan trioleate, alkylolamides, the condensation products of nonyl phenol with ethylene oxide or propylene oxide-ethylene oxide products.
• anionic type surfactants are used such as potassium stearate, potassium-processed rosin, and the alkali metal salts of alkylbenzene sulfonic acid.
• the hydrogenated latex which is used in accordance with this invention may be made by the process of United States Patent 4,452,950 issued to Wideman, the teachings of which are incorporated herein by reference in their entirety.
• the technique of Wideman is essentially a process for hydrogenating carbon-carbon double bonds in an unsaturated elastomeric polymer in latex form which comprises combining the unsaturated elastomeric polymer latex with (1) an oxidant selected from the group consisting of oxygen, air and hydroperoxides; (2) a reducing agent selected from the group consisting of hydrazine and hydrates of hydrazine; and (3) a metal ion activator.
• This hydrogenation reaction can be carried out at virtually any temperature within the range of about 0°C to about 300°C.
• Oxygen will typically be utilized in carrying out the hydrogenation procedure of Wideman. However, it is also possible to utilize air or other oxidants such as hydrogen peroxide, cumyl hydroperoxide, t-butyl hydroperoxide, p-menthane hydroperoxide, and the like.
• metals having ions or salts which will react with hydrazine can be utilized as the metal ion activator.
• Antimony, arsenic, bismuth, cerium, chromium, cobalt, copper, gold, iron, lead, manganese, mercury, molybdenum, nickel, osmium, palladium, platinum, cerium, silver, tellurium, tin, and vanadium are representative of metals having ions or salts which will react with hydrazine and which are accordingly useful in the hydrogenation technique of Wideman as the metal ion activator. Copper and iron are preferred metal ion activators with copper being most preferred.
• hydroquinone can be utilized to catalyze the reaction of oxygen with residual hydrazine in an aqueous emulsion of a rubber reduced in accordance with the process of Wideman.
• the level of residual hydrazine in a latex can be reduced from typical levels of about 1 to 2 percent to levels within the range of about 50 ppm to about 100 ppm. This can be accomplished by simply mixing oxygen and a small amount of the catalyst, such as hydroquinone, catechol, quinone, or o-phenylene diamine into the latex containing residual hydrazine. This procedure may be accelerated by increasing the catalyst concentration, temperature and oxygen pressure as desired.
• the hydrogenated latex can be of a polybutadiene rubber, polyisoprene, nitrile rubber, carboxylated nitrile rubber, styrene-butadiene rubber, styrene-isoprene-butadiene rubber, etc.
• Such hydrogenated rubbers will typically have a saturation level of about 70% to about 99%. It is preferred for the hydrogenated rubber to have a saturation level of about 95% to about 98%.
• the pH of the hydrogenated latex emulsion generally ranges from about 7.5 to 13. Preferably, the pH ranges from about 8 to 11.
• the preferred hydrogenated rubber latex is further treated to lower the hydrazine level, prior to forming the blend of the present invention.
• the hydrazine level may be lowered by mixing the hydrogenated latex with an effective amount of ozone for a period of time which is sufficient to attain the desired results.
• the temperature at which the ozone treatment procedure is carried out is not critical. In fact, virtually any temperature between the freezing point of the latex and its boiling point can be utilized. However, for practical reasons, the hydrogenated latex will normally be treated with ozone at a temperature which is within the range of about 0°C to about 60°C. A temperature within the range of about 15°C to about 30°C will most preferably be employed.
• the ozone treatment will be carried out for a time which is sufficient to eliminate undesirable levels of crosslinking and which is sufficient to reduce residual hydrazine concentrations to acceptable levels.
• the treatment time employed will typically be within the range of about 15 minutes to about 6 hours.
• the period of time utilized in treating the hydrogenated latex with ozone will more typically be within the range of about 30 minutes to about 2 hours.
• the gelation which can occur during the hydrogenation procedure is believed to be essentially due to crosslinking of the elastomeric polymer in the emulsion.
• an ozonolysis reaction occurs.
• the remaining double bonds in the crosslinked rubber are attacked with ozonides being formed.
• the ozonides formed under the low temperature condition of the reaction are highly unstable and are largely destroyed by basic hydrolysis at the elevated pH's of the latex. This results in the cleavage of the crosslinked elastomeric polymer into rubber segments of lower molecular weight which are generally terminated with aldehyde groups.
• Continued ozonolysis will subsequently oxidize a portion of the initial aldehyde groups to carboxylic acid groups.
• the terminal aldehyde groups on the rubber segments can also be reduced to alcohols by the addition of agents such as aqueous basic sodium borohydride solution at room temperature to approximately 80°C.
• the later blend can be utilized in a conventional manner.
• the latex can also be coagulated to recover a dry rubber. Standard coagulation techniques, such as salt-acid coagulation procedures, can be employed. If the hydrogenated latex component has been ozonated, additional coagulant is preferably used, the amount of which will be dictated by the level of carboxylate generated.
• Curing the dried rubber which is provided in accordance with the present invention may be cured by methods known to those skilled in the art. Such methods include sulfur and non-sulfur cure systems.
• the present invention will be described in more detail in the following examples. These examples are merely for the purpose of illustration and are not to be regarded as limiting the scope of the invention or the manner in which it can be practiced. Unless specifically indicated otherwise, all parts and percentages are given by weight.
• a nitrile rubber latex was hydrogenated by utilizing the general process of U.S. Patent 4,452,950 to a saturation level of approximately 95-98%.
• the hydrogenation was based on the following relative recipe: A 179.0 gram quantity of N612B NBR latex (commercially available from The Goodyear Tire &
• Poly-tergent 2EP® (a sodium dodecyldiphenylether disulfonate surfactant) from Olin Corporation in an amount sufficient to provide 0.0077.grams copper sulfate and 0.15 grams of surfactant were added to a 3 250 cm four-neck flask equipped with a mechanical stirrer, thermometer, reflux condenser and an inlet tube for feeding hydrogen peroxide.
• HNBR-1 This hydrogenated latex was designated as HNBR-1 and had a solids content of 9.8 solids.
• 465 ml of HNBR-1 was ozonized for 3 hours at room temperature by passing the entire ozone output of a T-408 Welsbach ozonator (air feed) through the latex. A total of 0.267 moles of 0-, was passed through the 465 ml during the 3 hour period.
• This batch was then combined with another batch of approximately 400 ml of hydrogenated nitrile rubber latex that was ozonated in a like manner.
• the combined ozonated latices had a solids content of 10.6% and was designated HNBR-II.
• An antioxidant masterbatch (AOMB) latex was used in preparation of all the samples.
• the antioxidant masterbatch was a 52/23/25 (by weight) terpolymer of butadiene/acrylonitrile/N-(4-anilinophenyl)- methacrylamide.
• AOMB antioxidant masterbatch
• the nonhydrogenated latex used to prepare the blends was Chemigum® N612B, a NBR latex commercially available from The Goodyear Tire & Rubber Company of Akron, Ohio.
• Example 1 Six latex blends (Samples A-F) were prepared using the dry weight ratio listed below:
• polymer blends (Samples 1-6) were compounded according to the recipes shown in Table II below.
• N-550 and N-770 are designations of carbon black types as per ASTM-D-1765.
• Zetpol 2020 is a hydrogenated NBR commercially available from Nippon Zeon Co. , Ltd. Zetpol 2020 has an acrylonitrile content of 36% and a Mooney viscosity of 80.
• Control Control. Control Control Control
• Samples 1-4 produced smooth surfaced clean vulcanizates. Samples 5 and 6 showed a textural surface. Controls 1-4 produced smooth surfaced clear vulcanizates.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=24731974

Family Applications (1)

Country Status (10)

Cited By (4)

Families Citing this family (13)

Citations (5)

Family Cites Families (3)

• 1991
  • 1991-04-04 US US07/680,657 patent/US5221714A/en not_active Expired - Lifetime
  • 1991-10-23 CA CA002053974A patent/CA2053974C/en not_active Expired - Fee Related
• 1992
  • 1992-02-13 AU AU17647/92A patent/AU649935B2/en not_active Ceased
  • 1992-02-13 BR BR9205822A patent/BR9205822A/pt not_active Application Discontinuation
  • 1992-02-13 WO PCT/US1992/001134 patent/WO1992017512A1/en not_active Ceased
  • 1992-02-13 DE DE69213446T patent/DE69213446T2/de not_active Expired - Fee Related
  • 1992-02-13 JP JP50966692A patent/JP3161731B2/ja not_active Expired - Fee Related
  • 1992-02-13 ES ES92910652T patent/ES2093258T3/es not_active Expired - Lifetime
  • 1992-02-13 EP EP92910652A patent/EP0580740B1/en not_active Expired - Lifetime
  • 1992-03-26 MY MYPI92000515A patent/MY106498A/en unknown

Patent Citations (5)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events