US3453252A - Stabilization of oxirane-containing fatty derivatives - Google Patents

Description

United States Patent 3,453,252 STABILIZATION OF OXIRANE-CONTAINING FATTY DERIVATIVES Rex J. Sims, Pleasantville, N.Y., assignor to Swift & Company, Chicago, 11]., a corporation of Illinois N0 Drawing. Original application Jan. 15, 1962, Ser. No. 166,420. Divided and this application Nov. 23, 1966, Ser. No. 596,455

Int. Cl. C08h 9/00; C07d 1/18; C08g 51/58 US. Cl. 260-975 7 Claims ABSTRACT OF THE DISCLOSURE Fatty, oxirane-containing compositions stabilized against loss of oxirane oxygen by presence of an antioxidant comprising a phenol having nuclear substituted alkyl radicals. Examples of the aforesaid phenols are butylated hydroxy toluene, butylated hydroxy anisole, propyl gallate gentisic acid, beta-naphthol, hydroguinone, Z-tertiary butyl-4-dodecyloxyphenol, 2-tertiary butyl-4-tetradecyloxyphenol, Z-tertiary butyl-4-octadecyloxyphenol or mixtures thereof.

This application is a division of application Ser. No. 166,420 filed Jan. 15, 1962, now abandoned.

This invention relates to the stabilization of oxygencontaining fatty derivatives and, more particularly, to stabilized oxirane-containing higher fatty derivatives protected against loss of oxirane oxygen and increases in acidity.

Oxirane-substituted higher fatty acids, higher fatty alcohols, higher fatty acid amides, and higher fatty acid esters are valuable compositions, particularly the esters of oxirane-substituted higher fatty acids and esters of oxirane-substituted higher fatty alcohols and the value of these compositions is attributable in many cases to the oxirane oxygen content of the composition. Oxirane-containing higher fatty acid esters, for example, have been found of significant value as plasticizers-stabilizers for halogen-containing compositions such as vinyl halide resins.

oxirane-containing glyceride oils and epoxidized fatty acid esters of mono-, di-, and polyhydric alcohols generally are employed widely as plasticizer-stabilizers in synthetic resins. These epoxy esters inhibit degradation of the vinyl resin and this inhibition has been attributed to the presence of the oxirane group. Also, the presence of the oxirane group in the ester appears to promote compatibility of the ester with resins.

These oxirane-substituted higher fatty derivatives undergo certain changes upon long periods of storage and when the materials are subjected to elevated temperature and/ or pressure as is encountered in the processing of resins with which they are formulated. These changes include an increase in acidity of the oxirane-containing material and a development of an objectionable odor and loss of epoxy oxygen accompanied by lessening of stabilizing properties and poorer compatibility with resins.

It is accordingly an object of this invention to stabilize oxirane-containing higher fatty derivatives against loss of oxirane oxygen and odor development and also preserve the stabilizing properties and compatibility of such de rivatives with resins.

A further object of the invention is the provision of oxirane-containing higher fatty derivatives stabilized against decreases in oxirane oxygen content.

Another object of the invention is the provision of synthetic plastics containing stabilized oxirane-substituted fatty materials which oxirane-substituted fatty materials retain plasticizer and stabilizing efiiciency as well as com- 'ice higher fatty derivatives having embodied therein protective agents for the group and synthetic plastic compositions containing oxirane-substituted higher fatty materials which plastics can be stored for long periods and/or processed and formulated at elevated temperatures without substantial decrease in oxirane content of the fatty material, Also within the contemplation of the invention are methods for inhibiting and preventing the oxidative degradation of the oxiranesubstituted fatty materials and the development of objectionable odors in such materials. The method of the invention involves the embodiment in such oxirane-substituted fatty materials of a protective amount of an organic phenolic composition.

More specifically, the invention provides epoxidized higher fatty acids, aromatic and lower aliphatic alcohol esters of such fatty acids, amides and hydrazides of such fatty acids, as well as esters of oxirane-containing higher fatty alcohols, stabilized against degradation and loss of oxirane oxygen by a small amount of a phenolic fat antioxidant.

While directed to oxirane-containing fatty materials generally, the stabilization is directed particularly to epoxy esters which are employed extensively in plasticizing vinyl halide resins. The oxirane-containing fatty acid derivatives to which the invention is particularly directed are the -mono-, di-, tri-, tetra-, and pentahydric alcohol esters of oxirane-containing fatty acids of 7-30 and preferably 10-30 carbons. Esters of such acids with monohydric aliphatic alcohols having 18 carbons and esters with dihydric aliphatic alcohols of 26 carbons, as well as with aliphatic polyhydric alcohols generally, are contemplated. Suitable monohydric alkyl and alkenyl alcohols providing the alcohol moiety of such esters include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, and octyl alcohols. Dihydric alcohols include the lower glycols as ethylene glycol, 1,2-propanediol, 1,3- propanediol, dimethylene glycol, trimethylene glycol, tetramethylene glycol up to and including hexamethylene glycol.

Benzenoid alcohols which may be employed in preparing the oxirane-containing fatty acid esters which can be advantageously treated in accordance with the invention are those benzenoid alcohols having less than 10 carbons and including benzyl, phenyl, 2-phenylethyl, 1- phenylethyl, and nuclear methylated phenyl alcohols.

The polyhydric alcohol esters of oxirane-containing fatty acids include the tri-, tetra-, penta-, and hexahydric alcohol esters of the fatty acid moiety. Included within this group are those aliphatic alcohols having 3-6 carbons and three or more alcohol groups. These include glycerol, erythritol, pentaerythritol, and hexitols such as mannitol and sorbitol. Mixed oxirane-containing esters such as those disclosed and claimed in U.S. Patent No. 2,978,463, issued Apr. 4, 1961, to F. E. Kuester et al. may also be used.

Highly epoxidized low by-product esters such as those disclosed in co-pending application S.N. 368,389, filed May 18, 1964, now Patent No. 3,377,304 are particularly well suited to treatment in accordance with the invention. These materials because of their high oxirane content and low hydroxyl and low polymer content are more compatible with vinyl resins than epoxy esters having a lower oxirane content and greater amount of byproducts. Because of the low by-product and low polymer content of these materials a higher level of compatibility with the resin is obtained and larger amounts of such esters can be employed in plasticizing a vinyl halide polymer.

The invention has particular application as applied to aliphatic monoand polyhydric lower alcohol esters of high oxirane higher fatty acids which contain a minimum of by-products such as polymers and hydroxylated esters. Those epoxidized fatty acid esters made from fatty acids having an oxirane content in the range of about 8.812.3% oxirane oxygen should have an infrared absorptivity at 2.9 microns (corrected for background) of .020 maximum. Other epoxy esters of fatty acids having an oxirane content of about 5.87% oxirane oxygen should have an infrared absorptivity at 2.9 microns (corrected for background) of .01 maximum. High oxirane linseed or perilla oil are examples of glyceride esters characterized by an absorptivity of .02 maximum at 2.9 microns while high oxirane soybean oil and 2-ethylhexyl esters of tall oil fatty acids, among others, have an absorptivity of .01 maximum at 2.9 microns.

The phenolic antioxidants Which are known in the art as fat antioxidants provide stabilization of the oxiranesubstituted compositions. Antioxidants such as butylated hydroxy anisole, butylated hydroxy toluene, and propyl gallate are representative of the group generally known as fat anti-oxidants. Commercial butylated hydroxy anisole is a mixture of 3-tertiary butyl-4-hydroxyanisole and Z-tertiary butyl-4-hydroxy anisole. Butylated hydroxy toluene (2,6-ditertiary butyl-p-cresol) is also an article of commerce. It is generally desirable to dissolve the additive or mixture of additives in a mutual solvent such as propylene glycol, ethanol, monoglycerides or like solvent in order to insure distribution of the stabilizer throughout the oxirane-containing composition.

The edible or nontoxic phenolic antioxidants are preferred for use in oxirane-containing esters which are to be used with vinyl halide resins designed for use around foods. The production of food packaging films from polyvinyl chloride requires that the film not contain inedible or toxic ingredients and thus epoxidized oils used in such formulations should contain stabilizers approved for food use. Further when the epoxidized oil is utilized in vinyl halide resins the stabilizer should be a composition which does not adversely affect the vinyl halide. For this reason stabilizers having amino groups are not favored in such formulations. Other suitable antioxidants useful in some applications are beta-naphthol, hydroquinone and compounds such as 2-tertiary butyl-4- decyloxyphenol, Z-tertiary butyl-4-dodecyloxyphenol, 2- tertiary butyl-4-tetradecyloxyphenol and Z-tertiar butyl- 4-octadecyloxyphenol. A preferred stabilizer mixture for use in oxirane substituted compositions to be used with polyvinyl chloride resins is as follows:

Percent by weight Propyl gallate 20 Citric acid Propylene glycol 70 Substitution of gentisic acid for propyl gallate in the above formulation results in an almost equally effective degree of stabilization.

Because the stabilizing efficiency of individual com- I positions and mixtures of such compositions vary, the

containing composition serves to satisfactorily stabilize against increase in acidity of the oxirane-substituted composition. Smaller amounts down to around .0025 appear to provide a beneficial result although amounts in the range around .02.04% appear to be optimum. While larger amounts can be used, up to around 5% Without adversely affecting the oxirane compositions, the use Of such large amounts may not be desirable inasmuch as the increased protection is not commensurate with the increase in the amount used. In some cases the use of larger amounts is advantageous as where the epoxidized fatty material is employed as a plasticizer-stabilizer for vinyl halide resins. Amounts in the range of 1-3 parts of antioxidant per hundred parts of resin in a vinyl chloride formulation improve processability of the resin and inhibit viscosity build-up.

The method for incorporating the stabilizers in the oxirane-containing derivative or in plastic formulations containing such oxirane derivative is not critical so long as the stabilizer is distributed throughout the mixture and maintained in contact with the oxirane-containing material. The stabilizer can be incorporated in the resinoxirane-containing composition mixture or the stabilizer can be incorporated in the oxirane-containing material as part of the manufacturing operation producing such material.

Best results in realizing the benefits of the invention are obtained, if the oxirane-containing composition is refined as by caustic refining. If an epoxidized glyceride, for example, is treated with sodium hydroxide, potassium hydroxide or other alkali to remove any acidic materials and/or peroxides, the effect of the stabilizer will be substantially increased. A convenient method for incorporating butylated hydroxy toluene and/or butylated hydroxy anisole in an epoxidized glyceride involves first dissolving the additives in a solvent such as propylene glycol, incorporating the solvent containing the additives in the glyceride oil and subsequently subjecting the oil to a steam deodorization step to remove volatiles which volatiles also include the glycol solvent. Alkali refining prior to addition of the stabilizer insures that no residual inorganic acid possibly employed in the production of the epoxidized composition will be present therein to accelerate degradation on storing.

Accelerated aging tests have been employed to demonstrate the stabilizing effect of the additives of the invention. This accelerated aging test involves placing the sample containing the stabilizer, as Well as a control sample with no stabilizer, in 50 gram amounts in open 100 ml. beakers in a laboratory electrically heated oven. The temperature of the oven is adjusted to a given temperature and observations are made after varying lengths of time. Other methods for testing stability of the epoxide can also be used and this method has been selected for simplicity and convenience.

The following examples which are intended to be illustrative and which should not be considered to place any limitation upon the invention, show the stabilizing effect of the phenolic antioxidants.

Example I The oxirane-containing material is epoxidized soybean oil having an oxirane content of 7.02%, an iodine value of 2, a Gardner color of less than 1, and an infrared absorptivity at 2.9 microns (corrected for background) of .01 maximum. This epoxidized soybean oil contains an average of over 4 reactive epoxy groups per molecule. A 50 gram sample of this epoxidized oil containing no stabilizer was compared with 50 gram samples of same oil containing .01% propyl gallate and a sample containing. .01% butylated hydroxy anisole and a sample containing .01% butylated hydroxy toluene. The samples were heated in the oven at C. for varying lengths of time up to 28 days and peroxide values, as Well as free fatty acid (as acetic acid) and oxirane analyses, were conducted. Table I shows the increase in acidity of the unstabilized sample and the inhibition of this acidity increase by the additives.

dized oil. SO-gram samples of the oil were placed in 100- milliliter beakers and while one sample containing no added stabilizer was employed as the control, varying TABLE I Percent Free Fatty Acid (as Acetic) Alter Number of Days Indicated at 85 C Sample 0 Days 7 Days 14 Days 21 Days 28 Days Sample I epoxidized Soybean Oil (Control) .013 .027 040 095 166 Sample I containing .017 propyl gallate .009 009 .016 030 Sample I conta ning .01% butylated hydr 009 009 .016 035 Sample I containing .01% butylated hydroxy toluene 009 008 016 052 Oxirane determinations were made after 14 and 28 15 days and the results are as follows:

TABLE II Percent Oxirane After Number of Days Indicated at 85 C.

Sample 0 14 28 Sample I epoxidized Soybean oil (Control). Sample I containing .01% propyl gallate Sample I containing 01% butylated hydrox an ole 7.07 Sample I containing .01% butylated hydroxy toluen 6.97

Sample Sample I, epoxidized Soybean oil (Control) amounts of butylated hydroxy toluene were added to the other samples and the increase in acidity and decrease in oxirane content after several days heating at 85 C. was noted. The results are tabulated in Table III, which follows:

TABLE III Percent Free Fatty Acid (as Acetic) After Number of Days Indicated at 85 C.

0 Days 7 Days 14 Days 21 Days 28 Days 0125 0338 074 084 129 Sample I containing 002.5% butylated hydroxy toluene. 0303 054 075 103 Sample I containing 005% butylated hydroxy toluene- 0267 050 .065 104 Sample I containing 01% butylated hydroxy toluene 0171 036 .037 084 Sample I containing .02% butylated hydroxy toluene- 0155 036 025 025 Sample I containing 04% butylated hydroxy toluene 0161 034 026 .018

The stabilized epoxidized soybean oil samples also ex- Oxirane determinations were made after 14, 21, and 28 hibited far greater compatibility in vinyl chloride fordays. The increasing effectiveness of the stabilizer in inmulations than the unstabilized control. While films prehibiting loss of oxirane oxygen as increasing amounts are pared from polyvinyl chloride resin formulations plasadded can be seen.

TABLE IV Percent Oxirane After Number of Days Indicated at 85 C.

Sample 0 Days 14 Days 21 Days 28 Days Sample I, epoxi zed Soybean oil (Control) 7. 02 7t 03 6. 87 6. 77

Sample I contai ing .0025% butylated hydroxy toluene 7 03 6. 93 6 89 Sample I conta ing 005% butylated hydroxy toluene 7 03 6. 91 6 87 Sample I conta' mg .01% butylated hydroxy toluene 7. 05 6. 98 6. 91

Sample I containing 02% butylated hydroxy toluene. 7.07 7.00 7. 00

Sample I containing 04% butylated hydroxy toluene 7.07 7. 00 7 00 ticized with the control sample showed considerable exudation of the plasticizer films prepared from similar polyvinyl chloride resin formulations plasticized with the stabilized epoxided oils were substantially free of exuded plasticizer.

Example II The epoxidized soybean oil employed in the tests recorded in the preceding example was employed to demonstrate the increased efiectiveness of butylated hydroxy toluene when added in increasing amounts to such epoxi- Example III TABLE V Percent Free Fatty Acid (as Acetic) After Number of Days Indicated at C Sample 0 Days 7 Days 14 Days 21 Days 28 Days Epoxidized 2'ethylhexyl tallate (Control) 036 169 246 38 56 Sample I containing .01% butylated hydroxy tolu 036 .35 232 30 38 Sample I containing .1% butylated hydroxy toluene 036 O82 071 096 172 Sample I refined with aqueous sodium hydroxide and taining .02% butylated hydroxy toluene .036 .016 034 Oxirane determinations for these samples were conducted and the results are as follows:

TABLE VI Percent Oxirane After Number of Days Indicated at 85 0.

Sample Days 14 Days 21 Days 28 Days Epoxidized Z-ethylhexyl tallate (Control) 4. 90 Sample I containing .01% butylated hydroxy toluene 90 Sample I containing 1% butylated hydroxy t0luene Sample I refined with aqueous sodium hydroxide and c n taining 02% butylated hydroxy toluene It can be seen that alkali refining of the epoxidized ester aids considerably in stabilizing effectiveness.

Example IV The oxirane-containing material employed in this test is high-oxirane linseed oil having an oxirane oxygen value of 9.22%, an iodine value of 4, a Gardner color less than 1, and infrared absorptivity at 2.9 microns (corrected for background) of .020 maximum. The epoxidized linseed oil has a low polymer content and a low hydroxyl content, as illustrated by the infrared absorption. In addition, the low viscosity (8.8 poises) is further evidence of the low polymer content.

Varying amounts of butylated hydroxy toluene were added to this oil and the stabilizing effect as compared to a control sample having no stabilizer added was determined by free fatty acid content and oxirane oxygen values.

TABLE VII with the exception that stabilized epoxidized soybean oil was substituted for the unstabilized plasticizer. This stabilized oil contained .05 based on the weight of the oil of a stabilizer mixture made up of 20 parts propyl gallate, 10 parts citric acid, and 70 parts propylene glycol.

The two batches were worked on a 2-roll mill for 5 minutes at 330 F, with the roll speeds being adjusted to and 60%. Small pieces, 6" x 6" were cut from the films obtained and these small pieces were placed in a preheated (345 F.) chrome mold. The mold was placed in a Carver Press so that the heating plates of the press were in contact with the mold. The contact pressure was maintained for 5 minutes, while the temperature was held at 345 F. and then the pressure was increased to 20,000 p.s.i. The mold was held under this pressure for 5 minutes. After cooling, the pieces were removed from the mold and placed in a Fadeometer for 100 hours. Examination of the films after 100 hours showed that the film Percent Free Fatty Acid (as Acetic) After Number of Days Indicated at 85 C Sample 0 Days 7 Days 14 Days 21 Days 28 Days Epoxidized Linseed oil (Control) .018 .051 083 107 Sample I containing 02% butylated hydroxy toluene .018 .032 .035 .019

TABLE VIII Percent Oxirane After Number of Days Indicated at 85 0.

Sample 0 Days 7 Days 14 Days 21 Days 28 Days Epoxidized Linseed oil (Control) 9.22 9.16 9.10 8.92 Sample I containing 02% butylated hydroxy toluene 9. 22 9.18 9. 23 9. 20

Typical of the vinyl halide polymers with which the prepared from the epoxidized oil containing no stabilizer stabilized epoxidized fats are most useful are those polyexhibited some loss of gloss and some exudation, while mers in which at least 50% of the monomer units prior the film prepared from the formulation having stabilized to polymerization are vinyl halide units. This includes epoxidized oil was substantially free of exudation and polyvinyl chloride, polyvinyl bromide, polyvinyl fluoride, Was characterized by good gloss. polyvinylidene chloride, vinyl chloride-vinylidene, chlo- The stabilizers employed herein are compatible with ride copolymers, vinyl chloride, vinyl acetate copolymers other materials employed in vinyl halide resin formulaas well as homopolymers and interpolymers of vinyl hations such as lubricants, heat stabilizers (such as the lides. Other monomers which may be copolymerized with metal salts) and antistatic agents. The alkyl phenols can vinyl halides include vinyl ketones such as vinyl butyl be employed alone or in combination to obtain the suketone, the acrylates and lower alkyl acrylates and alkperior stabilization. In addition, stability enhancing maacrylates as well as lower alkyl esters of maleio and futerials can be employed with the phenolic stabilizers. maric acids. Thgse enhancing agents include citric acid, phosphoric aci etc. j 16 V The stabilizers impart improved color stability to poly- A formulation contalnmg the followlns mgredientsr vinyl chloride resin compositions containing the stabilized Parts oxirane-containing fatty materials. The improvement in Polyvinyl chloride 100 l r stability in the polyvinyl chloride compositions E idi d soybean 11 after formulation on extruders and after exposure to ele- (oxirane oxygen 7%) 40 Vated mperat res is Substantial. This improvement has Zinc stearate A been noted at low levels of the stabilizer around .01-.1% Mineral oil l and also at much higher levels in the range of up to 5%.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and, accordingly, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. Esters of oxirane substituted higher fatty acids of 7-30 carbon atoms containing at least about .0025% based on the Weight of the oxirane containing composition of an alkyl substituted phenol selected from the group consisting of butylated hydroxy toluene, butylated hydroxy anisole, propyl gallate, gentisic acid, beta-naphthol, hydroquinone, Z-tertiary butyl-4-decyloxyphenol, 2- tettiary butyl-4-dodecyloxyphenol, 2-tertiary butyl-4- tetradecyloxyphenol, 2 tertiary butyl 4 octadecyloxyphenol, and mixtures thereof.

2. The product of claim 1, wherein said esters contain about .00255% based on the Weight of said esters of said phenol.

3. The product of claim 1, wherein said phenol is butylated hydroxy toluene.

4. The product of claim 1, wherein said phenol is butylated hydroxy anisole.

References Cited UNITED STATES PATENTS 2,759,829 8/1956 Mattill et al. 260-3985 2,981,628 4/1961 Hall 252-404 3,225,001 12/1965 Darsa 260-23 3,322,707 5/1967 Annonio et a1. 260-23 3,326,828 6/1967 De Melio 260-23 3,377,304 4/ 1968 Kuester et a1. 260-23 HOSEA E. TAYLOR, JR., Primary Examiner. W. E. PARKER, Assistant Examiner.

US. Cl. X.R. 252-404; 260-99, 236.6, 348, 398.5