US3657133A - Preservative for elastomers - Google Patents

Abstract

FUNCTIONAL FLUIDS NOT DAMAGING TO ELASTOMERS, I.E. RUBBER SEALS, CONSIST ESSENTIALLY OF A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL AND A MINOR AMOUNT EACH OF (1) AN OIL SOLUBLE ALKALINE EARTH METAL SALT OF A CONDENSATION PRODUCT OF AN ALKYL PHENOL AND AN ALDEHYDE AND (2) A LONG-CHAIN ALIPHATIC POLAR CONTAINING COMPOUND, I.E. ALIPHATIC ALCOHOLS, MONOCARBOXYLIC ACIDS AND POLYALKYLENE GLYCOLS.

Description

United States Patent Olfice 3,657,133 PRESERVATIVE FOR ELASTOMERS James R. Miller, Florissant, Mo., assignor to Shell Oil Company, New York, N.Y.

No Drawing. Continuation-impart of application Ser. No. 524,846, Feb. 3, 1966. This application Dec. 27, 1967, Ser. No, 693,759

Int. Cl. C09k 3/00, 3/02 US. Cl. 252-76 5 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of application Ser. No. 524,846, filed Feb. 3, 1966, and now abandoned.

Th present invention relates to conservation of resilience and control of swelling of .elastomers when in contact with functional liquids such as transmission fluids. More particularly, the present invention is directed to hydrocarbon base functional fluids which are capable of preserving and not cause hardening, cracking and loss of flexibility and tensile strength of elastomers.

The control of swelling and the conservation of resilience of elastomer seals, packings and gaskets is a major problem in the performance of functional fluids such as transmission oils, hydraulic fluids and various types of related lubricants, particularly in view of recent design changes of such systems which have resulted in increased severity of the applications. Thus, the use of smaller volume and more compact automatic transmissions has resulted in higher working temperatures for such fluids causing greater degree of interaction with the elastomer resulting in more rapid deterioration of both the fluid and elastomer surfaces. This causes serious problems requiring costly repairs due to leakage, wear and the like.

It has now been discovered that elastomers such as rubber seals and gaskets in contact with functional fluids such as are used in transmission systems can be made to retain their swelling, flexibility and tensile strength by incorporating into such functional fluids a minor amount of an additive mixture consisting of (1) an oil-soluble neutral and/or basic alkaline earth metal salt of a condensation product of an alkyl phenol and a lower aldehyde said condensation product having the formula:

wherein X is a member selected from the group consisting of H and 3,657,133 Patented Apr. 18, 1972 R is alkyl of 4 to 18 carbon atoms, R is a member selected from the group consisting of H, lower alkyl and lower alkenyl each having from 1 to 6 carbon atoms and phenyl, M is an alkaline earth metal salt and n is a whole integer from 0 to 13 inclusive and (2) a long-chain aliphatic polar-containing organic compound selected from the group consisting of (a) a saturated aliphatic alcohol containing 12 to 22 carbon atoms, (b) a saturated aliphatic monocarboxylic acid containing 12 to 22 carbon atoms and (c) a polyalkylene glycol, the alkylene radical containing 4 to 8 carbon atoms. The additive mixture of 1) and (2a-c) functions synergistically in various functional fluids such as liquid hydrocarbons having low, medium or high aromatic content as determined by the aniline point using standard ASTM method D 611-551. By oils having such aniline points is meant that an oil having an aniline point of 157 F. is low, 199 F. is medium and 255 F. is high. The amounts of each additive which can be added to a functional fluid can vary between 0.5% and 15% and preferably between 1 and 10% by weight.

The X-,

and R- substituents may be attached to the phenolic radical in either the ortho or para position in the above mentioned oil soluble condensation product. In general the majority of the X- and substituents are linked to the phenolic radical in the ortho position, and the R-substituent is linked in the para position, however, it is possible that certain of the X and product of p-octyl phenol and formaldehyde having the formula:

wherein X is H or CH OH and m is an integer from 2 to 8.

The alkaline earth metal salts of a condensation product of alkyl phenol and a lower aldehyde can be prepared by means well known in the art such as by first condensing at an elevated temperature, an alkyl phenol, e.g., octyl phenol with an aldehyde, e.g., formaldehyde in the presence of a suitable solvent, e.g. mineral lubricating oil, and catalyst, eg a mineral acid. The condensation product is then removed and dispersed in a hydrocarbon oil to which is added the metal forming compound such as hydrated lime and the entire mixture agitated at an elevated temperature until the calcium salt of said condensation reaction forms. The salt formed can be purified by solvent treatment and filtration.

Instead of forming the salt in a two step process it can be formed in one step by simply admixing in a suitable solvent and alkyl phenol, an aldehyde and for example, hydrated lime and reacting the mixture at an elevated temperature under agitation until the calcium salt of the alkyl phenol-aldehyde condensation reaction forms. The product is recovered and purified by conventional means. Alkyl phenols useful for this reaction include C alkyl phenols, e.g., butyl, amyl, octyl, nonyl, dodecyl, octadecyl phenols. Aldehydes having not more than 7 carbon atoms can be used as for example formaldehyde, acetaldehyde, crotonaldehyde, butyraldehyde, benzaldehyde and the like. The alkaline earth metal compounds used to form the end product can be calcium, barium, and/or strontium oxide, hydroxide or carbonate. A more detailed procedure for preparing the salts of the phenol-aldehyde condensation products may be found in US. Pats. 2,250,188 and 2,647,873.

The other essential additives include (2a) long-chain alkanols having 12 to 22 carbon atoms such as dodecyl, tetradecyl, cetyl, stearyl alcohols; (2b) saturated fatty acids having 12 to 22 carbon atoms, e.g., lauric, myristic, palmitic, stearic acids and (2c) polyalkylene glycols where the alkylene radical contains 4 to 8 carbon atoms having the general formula where R" is an alkylene radical having 4 to 8 carbons, e.g., butylene, amylene and the like, and a is an integer such that the total molecular weight of the glycol ranges from 400 to 5000, preferably from 500 to 1000 and such compounds can be illustrated by polybutylene oxide glycol having a molecular weight of 500 to 1000.

The elastomeric materials which are preserved from damage by being in contact with liquid hydrocarbons such as mineral oils, particularly mineral oils rich in aromatics or mineral oil compositions such as are used in transmission and hydraulic systems include natural and synthetic rubbery materials such as derived from polymerization of open-chain conjugated dienes, e.g., butadiene-1,3, etc., and copolymers of such materials with polymerizable compounds, e.g., acrylonitrile, methyl methacrylate, styrene, methyl styrene, vinyl halides and the like, and are illus trated by rubbers derived from copolymers of butadiene- 1,3 and acrylonitrile, copolymer of butadiene-1,3 and styrene. Still other synthetic rubbers include acrylic elastomers such as polymethyl or ethyl acrylates or copolymers of methyl acrylate and chloroethyl vinyl ether or silicone rubbers, e.g., dimethyl silicone rubber and the like.

A particular embodiment of the present invention is the preservation of rubber sealants in various power transmission systems, e.g., transmission and hydraulic systems, torque converters, etc., by addition to functional fluids employed in such systems a minor amount of from 0.5% to about 15%, preferably from about 1% to about 10% by weight of each of the compounds represented by (1) and (2a-c) and fully described above. The functional fluids useful in this invention are well known in the art and can be either natural mineral lubricating oils or synthetic oils such as organic esters, organic phosphates and polyethers. These lubricating oils must meet the specification requirements described in the SAE Handbook, 1961 for hydraulic fluids, transmission and axle type lubricant or torque converter fluids and also those required by the automotive industry for transmission fluids Type A or Type A, Suffix A or Type C. Typical properties of these fluids are described in US. Pat. 2,982,734. These fluids may also contain minor amounts (0.1-5% by weight) of improving agents such as alkyl phenols and arylamine inhibitors, detergents such as polyvalent metal petroleum sulfonates; oiliness or antiwear agents such as sulfurized fatty materials and viscosity index and pour point improvers such as polymerized alkyl acrylates, e. g., polymerized lauryl methacrylate in the molecular weight range of 15,000 to 500,000.

Examples of useful transmission fluids which render transmission systems leak proof by addition of additive mixtures of the present invention are shown below.

Composition A: Percent Ca salt of p-octyl phenol-formaldehyde condensation product (av. MW=1000) 4 Stearic acid 2 Mineral lubricating oil (HVI 100 N)* Balance Composition B:

Ca salt of p-octyl phenol-formaldehyde condensation product (av. MW=1000) 2.1 Octadecyl alcohol 0.9

Mineral lubricating oil (blend of HVI N and 20% LVI 65 N) Balance Composition C:

Ca salt of p-octyl phenol-formaldehyde con- The essence of the present invention is illustrated by the following tests, the results of which are shown in Table A.

TESTS I Immersion Test (ASTM-D 47157T) Elastomer aged in 300 ml. of test oil at 300 F. for various periods of time and volume change noted.

II Hardness Test (ASTM-D 676 Method using a Shore durometer Type A-2).

III Flexibility Test (Measured by bending specimen over a A -inch mandrel and noting extent of cracking).

TABLE A.RUBBER-BUNA N, COPOLYMER OF BUTADIENE/ACRYLONITRILE RUBBER Test I II III Immer- Volume Hardness Flexibility sion time, change, change, (visual Composition hrs. percent duron pts. observation) 1 Neat mineral lubricating oil (HVI 100 N) 168 2 to 3. +14 to +16 B5101? in a 1a Mineral lubricating oil (80% HVI 100 N plus 192 -0.5 14 Do.

LVI 65 N 2 Mineal lubricating oil (HVI 100 N) 2% Steario 168 +23 3 Excellent.

ac 2a Mineral lubricating oil (HVI 100 N) plus 6% 168 +32 3 Do.

stearic acid. 3 Mineral lubricating oil (HVI 100 N) plus 3% 168 3 +17 Broke in octadecyl alcohol. half. 3a Mineral lubricating oil (80% HVI 100 N plus 168 3 +17 Do.

20% LVI 65 N) plus 6% octadecyl alcohol. 4 Mineral lubricating oil (HVI 100 N) plus 2% 225 1. 6 to 3. 6 16 to 17 D0.

Ca salt of octyl phenol-formaldehyde condensation porudct (av. MW= 1000). 4a Mineral lubricating oil (HVI 100 N) plus 5% 226 3.6 16 to 17 D0.

Ca salt of octyl phenol-formaldehyde condensation product (av. MW=1000). 5 Mineral lubricating oil (HVI 100 N) plus 2% 158 4. 3 8 )1 cry deep polybutylene oxide glycol (MW=500). cracks. 5a Mineral lubricating oil (HVI 100 N) plus 6% 158 4.3 8 Do.

polybutylene oxide glycol (MW=600) 6 Composition A (present invention). 329 0 1 to 0. 3 0 Excellent. 7 Composition B (present invention). 192 1. 4 0 Do. 8 Composition 0 (present invention). 463 0.6 3 Do. 9 Composition D (present invention) 463 1 6 2 Do.

I claim as my invention:

a 8 030a 1. A hydraulic fluld which is not damagmg to rubber a a 1 l seals consisting essentially of a major amount of a minoral or synthetic lubricating oil and from 0.5% to about l 15% by Weight each of (1) an oil-soluble alkaline earth metal salt of a condensation product of an alkyl phenol and an aldehyde, said condensation product having the for- 08E" 6 m 8H" mula:

Oil 0 M wherein X is a member selected from the group consisting of H and R is alkyl of 4 to 18 carbon atoms, R is a member selected from the group consisting of H, alkyl of 1 to 6 carbon atoms, alkenyl of l to 6 carbons and phenyl, M is an alkaline earth metal salt and n is an integer from 0 to 13 inclusive and (2) a long chain aliphatic polar-containing organic compound selected from the group consisting of alkanols containing 12 to 22 carbon atoms, saturated monocarboxylic fatty acids containing 12 to 22 carbon atoms and polyalkylene glycol, having an alkylene radical containing from 4 to 8 carbon atoms and a molecular weight from about 4005,000.

2. The composition of claim 1 wherein the oil soluble condensation product (1) is a calcium salt of p-octyl phenol and formaldehyde having the formula:

wherein X' is H or CH OH and m is an integer from 2 to 8 inclusive and the polar containing compound (2) is octadecyl alcohol.

3. The composition of claim 1 wherein the polar containing compound (2) is stearic acid.

4. The composition of claim 1 wherein the polar con taining compound of (2) is a polyalkylene glycol, the alkylene radical containing 4 to 8 carbon atoms.

5. The composition of claim 4 wherein the polyalkylene glycol is polybutylene oxide glycol having a molecular weight from about 5001000.

LEON D. ROSDOL, Primary Examiner H. A. PITLICK, Assistant Examiner US. Cl. X.R.