US3719664A - Warp sizing agent - Google Patents

Abstract

A method of acylating starch with dibasic acid anhydrides and forming salts of the acylated starch with amines devoid of Zerewitinoff hydrogen at pH 5.0-7.0 The resultant amine slats of the starch half esters are useful as sizing agents for yarns containing synthetic fibers.

Description

United States Patent Hayes et al.

[4 1 March 6,1973

WARP SIZING AGENT Inventors: Lester P. Hayes; Raymond L. Drury, Jr.; Edward H. Grosse, all of Decatur, Ill.

A. E. Staley Manufacturing Company, Decatur, Ill.

Filed: Oct. 27, 1971 Appl. No.: 192,841

Related US. Application Data Continuation-impart of Ser. No. 12,859, Feb. 19, i970, abandoned.

Assignee:

US. Cl. "260/2335, 106/210, 106/2l3,

106/214 Int. Cl. ..C08b 25/02 Field of Search ..l06/2l0, 214; 260/2335 Primary ExamirierTheodore Morris Att0rneyHoward J. Barnett [57] ABSTRACT A method of acylating starch with dibasic acid anhydrides and forming salts of the acylated starch with amines devoid of Zerewitinoff hydrogen at pH 5.0-7.0 The resultant amine slats of the starch half esters are useful as sizing agents for yarns containing synthetic fibers.

6 Claims, No Drawings WARP SIZING AGENT This is a continuation-in-part of copending application Ser. No. 12,859 filed Feb. 19, 1970 now abancloned.

This invention relates to novel starch compositions and to sizing compositions based thereon. The compositions of this invention are especially useful in sizing hydrophobic yarns, such as polyesters, polyamides and polyacrylics and their blends with hydrophilic fibers such as cotton, wool and rayon, The invention relates to thinned, slightly hydrophobic starch compositions, more particularly to amine salts of starch half esters of dicarboxylic acids, and still more particularly to amine salts of starch half esters of maleic acid.

In weaving, warp yarn is subject to abrasion and to considerable stress by cyclic stretching. Stretching tends to cause breaking of the yarn, and abrasion promotes breaking by weakening the yarn. Breaking of the yarn reduces weaving efficiencyrMoreover, abrasion results in weight loss of the fabric. The material shed in abrasion tends to pill and the pills tend to be woven into the fabric, Also, the necessary removal of shed material from the work room adds to the cost of the weaving process.

To cope with these and other problems and particularly to improve weaving efficiency, the warp yarn is customarily coated before entering the loom. This coating operation is known as warp sizing, pr slashing." In the sizing operation, a filmrforming material is deposited on the yarn. The film strengthens and protects the yarn, and imparts lubricity which reduces abrasion. Warp size agents are usually used in conjunction with waxes so as to augment the lubricity of the film formed on the yarn. In order to attain high weaving efficiency, conventional starch-based warp size is usually used with substantial amounts of binders, such as urea and acrylic polymers. A typical sizing solution contains about percent solids for blended fiber yarns, 10l2 percent for 100 percent cotton fiber yarn of which the sizing agent is the major and the wax is a minor part; about 5-6 weight percent sizing wax based on warp size starch is commonly used.

Starches have been used to size hydrophilic yarns such as cotton. Synthetic fibers, such as nylon and polyesters, are more hydrophobic than cotton so that sizing agents satisfactory in sizing cotton have proved unsatisfactory when applied to synthetics and their blends with cotton. Certain modified starches, such as acetylated starches and hydroxyethylated starches, have been proposed and used for the sizing of blends of synthetics and cotton. Within certain limits, the sizing effectiveness of these modified starches depends apparently more on the degree of substitution than on structural differences between substituent groups. Moreover; when unsupported films are made of modified starches having comparable sizing effectiveness, the films have comparable maximum elongation before breaking. A number of warp size films exhibit about 2.5 to 4 percent elongation; whereas unmodified starch films exhibit elongation of about 3 percent or less.

Improved film elongation usually indicates improved ability of the warp size film on yarn to retain its integrity under weaving conditions. The superior elongation of substituted starch films compared to unsubstituted starch films has been related to a steric effect. According to this view, the rigidity of ordinary (unmodified) starch films is related to extensive hydrogen bonding between adjacent molecular segments. Substituents on starch act as spacers between molecular segments thereby inhibiting hydrogen bond formation between the segments. This reduces the total hydrogen bonding and increases film elongation.

This invention is directed to starch-based warp sizing agents having improved film elongation. The invention involves substituted starches in which the substituent radicals comprise carboxyl groups and amines. The invention involves particularly amine salts of certain carboxylated starches, especially maleated starches. The invention involves further a novel method of making such salts. The substituents as defined above (carboxylate salt groups) will be referred to hereafter as sizing substituents.

The invention provides new and effective warp sizing agents especially for hydrophobic fibers which are obtained by simple reactions from starch and other common materials. In the preferred embodiment of our invention, these warp sizing agents are obtained from starch, maleic anhydride and tertiary amines. One aspect of the invention is directed to an improved sizing material for hydrophobic yarn which are especially useful for yarns having at least 50 percent polyester or nylon or acrylic fiber, and are useful for blends containing as little as 25 percent polyester, nylon or acrylic fiber.

US. Pat. No. 3,038,395 is directed to a reaction in which a non-granular amylose obtained by starch fractionation was dissolved in dimethylsulfoxide, and then treated with maleic anhydride and triethylamine. Upon precipitation, a non-granular water dispersible product was obtained which was described as a starch half ester of maleic acid which formed a water-resistant film on deposition from water. There is no indication here that an amine salt was formed. The above reference states that similar results were obtained using octenyl succinic anhydride and phthalic anhydride, respectively, as reagents.

The substituted starches according to this invention may be derived from corn, wheat, potato, sorghum, waxy maize, tapioca, rice and sweet potato starches, or their oxidized forms. Other starches or their derivatives may also be used, including those derived from genetic varieties of corn and yield high amylose starch. Examples of such derivative starches are hydroxyalkyl starch ethers, including hydroxypropyl and hydroxyethyl starch ethers, and starch esters of monocarboxylic acids such as acetic and propionic acids. Any of the above listed starch varieties can be used as the base for the new starch derivatives of the invention. Moreover, the starches may be partially depolymerized by oxidation, acid thinning, or enzymatic hydrolysis.

The sizing substituents of the starches made according to the invention comprise amine salts of carboxylic acids, the carboxyl groups resulting from the reaction of a dicarboxylic acid anhydride with a starch hydroxyl group. In the preferred sizing substituent, both the amine and the dicarboxylic acid anhydride used are aliphatic in nature; for example, the tertiary aliphatic amine salt of starch maleate half ester is a preferred substituent. Variations in structure of the sizing substituents are contemplated. Thus, substituents having aromatic rings such as a phthalate half esters of starch, are within the scope of the present invention as are cycloaliphatic and heterocylic amines such as N,N- dimethylcyclohexylamines and N-methylmorpholine. The sizing substituent may be saturated or partially unsaturated. Further details will be presented following the disclosure of our new starch maleation procedure. Other dibasic acid anhydrides such as succinic, citraconic anhydride, and cyclohexenedicarboxylic acid anhydride may also be used in this invention.

A wide variety of tertiary amines may be used, including aliphatic tertiary amines such as trimethylamine, N,N-dimethyl-tertbutyl-amine, N,N- dimethyloctylamine, Z-dimethylaminoethyl acetate; triethylamine, tripropylamine and tributylamines are preferred amines. N,N-dimethyl-aniline is an example of an aromatic amine which can be used. The amine selected may affect the degree of hydrophobicity imparted by the sizing substituent to the starch.

Tertiary amines are preferred, because amines having active hydrogen tend to undergo various reactions which interfere with the formation or the stability of half-ester salts of starch. Thus, primary and secondary amines tend to react with maleic anhydride, forming amides (maleamic acids) or even to add to the ethylenic double bond. These amines also tend to aminolyze esters and thereby to reverse the formation of starch esters. Tertiary amines are particularly suitable in the preparation of starch-based warp sizing agents according to this invention, because they are devoid of active hydrogen. Amines having inactive hydrogen attached to nitrogen may also be used. The hydrogen atoms may be inactive due to steric hindrance as in the case of di(sec. butyl) amine, or because of electronic effects as in aromatic amines having electron withdrawing substituents such as paranitroaniline. In general, the useful amines are those containing no active (Zerewitinoff) hydrogen.

The desired degree of substitution of the starch with sizing substituents may range from 0.005 to 0.1, and the number of carbon atoms in the acid group plus the largest radical or the amine should not exceed 14. For example, for the starch maleate, the longest alkyl chain is ten carbon atoms in length.

Additional substitutions in the sizing substituents are permissible as long as they conform to the following considerations.

The sizing substituents as a whole should be hydrophobic rather than hydrophilic. Nevertheless care should be taken not to impart an overly hydrophobic character to the starch. If excessively hydrophobic, the size may be difficult to remove following weaving since desizing is usually done with the aid of aqueous chemical or enzymatic treatment and in either case, the size film must be readily wettable by water to facilitate desizing. Wettability must be considered when selecting the sizing substituents and determining the degree of substitution of the starch derivative. If a highly hydrophobic sizing substituent is used, an undue degree of hydrophobicity may be imparted to the starch at a lower degree of substitution than in the case of a less hydrophobic substituent.

The amine salt substituent as a whole should not be unduly hydrophilic, as this tends to lower film adhesion to hydrophobic yarn. In addition, groups imparting hydrophilic character are themselves prone to interact with the hydroxyl groups of the starch molecule, thereby reducing the desired extensibility of the sizing film. Partial cyclic structures can be contained in the chain of the sizing substituent, but should be limited in number, because these structures tend to impart undesirable rigidity to the substituent group. Sizing substituents including a large number of polar groups combined with hydrophobic groups should be avoided, since such a combination can cause undesirable foaming of the sizing composition during the sizing operation.

The new starch-based warp sizing agents of this invention are surprisingly effective at a low level of substitution as compared to the much higher degree of substitution in other starch derivatives previously proposed and used as warp sizing agents. Hydroxyethyl degree of substitution of about 0.08 to 0.12, and acetyl substitution of 0.13, have been proposed in US. Pat. No. 3,144,351. In contrast thereto, triethylaminc compound of maleated starch obtained according to this invention is highly effective at levels as low as 0.007 in sizing cotton-polyester blends, i.e., at less than one tenth of the previously proposed degree of substitution in the case of hydroxyethyl and of acetyl substituents. It should be noted that unsupported films of starch treated with maleic anhydride and triethylamine have improved elongation, compared to films of conventional warp size starch, i.e. 6-7 percent as compared to about 4 percent, despite the low degree of substitution.

Generally warp sizing must exhibit good film elongation in order to remain bound to the yarn while it undergoes stretching during the weaving process. If the sizing film is too inelastic it tends to lose its integrity on the yarn, along with its protective function. The more flexible, elastic sizing films made according to this invention stretch with the yarn, and provide better protection for the yarn fibers during weaving.

Our sizing substituents are believed to be more effective spacers, hence more effective suppressors of hydroxyl bonding between adjacent molecular segments than previously proposed ones, whereby they facilitate better film elongation. This improvement is believed to be due to chain length, and in some instances, due to the cumulative effects of chain length and molecular branching.

In the case of the maleated starches, the ethylenic double bond of the maleyl moiety of the sizing substituent is believed to enhance the separation of starch chain segments because the rigid double bond is located near the starch molecule and the sizing substituent is kept from aligning itself as closely to the starch molecule as might otherwise occur.

Our hydrophobic substituents are also believed to improve the adhesion of the sizing film to the hydrophobic fiber, and appear to facilitate wax take-up by the film thus further promoting the separation of molecular segments of the starch and thereby contributing to the elongation of the film, and adding to desirable film lubricity.

In general terms, our compositions comprise salts of weak acids and weak bases. These are not as highly ionic or as hydrophilic in character as they might otherwise be if either a strong acid or strong base component is used. Aqueous solutions of weak acids and weak bases tend to be partly hydrolyzed rather than ionized, existing in ionic form to a lesser degree than the analogous compositions in which the amine is replaced by the cation of a strong base such as the sodium ion. The association of carboxyl groups and tertiary amines is primarily covalent, rather than ionic in the dried films. Consequently, salt formation, e.g., by means of tertiary amines with half esters of starch does not produce hydrophilic substitution, as one would expect when the cation of a strong base is used instead of the amine. For example, sodium salts analogous to the amine salts of this invention tend to produce films which are brittle and inflexible, and therefore have less warp sizing efficacy than the corresponding triethylamine salts.

Improved starch-based warp sizing agents of this invention are prepared by treating starch with dibasic acid anhydrides and amines. Preferably, we make and use tertiary amine salts of half esters of starch in our sizing compositions. We utilize low cost, readily available starting materials in a simple reaction at moderate temperatures.

The treatment of starch with maleic anhydride and other dibasic acid anhydrides is known (U.S. Pat. Nos. 2,461,139 and 2,661,349, for example). In these treatments, the sodium salt of the starch half maleate, or other starch half esters of a dibasic acid is usually ob tained, and such salts can be converted to the corresponding amine salts by decomposing the sodium salt dilute hydrochloric acid and adding amines, or by addition of a preformed amine hydrochloride to the sodium salt.

Amine salts of this invention may be prepared by analogously applying previously known reaction sequences for the preparation of amine salts of carboxylic acids. Thus, starch may be acylated with dibasic acid anhydrides as described in U.S. Pat. No. 2,461,139 with the addition of alkali which results, e.g., in the sodium salt of the starch half ester. The alkali metal salt may be decomposed by the addition of strong acid, and the free carboxylic acid treated with amine to produce the amine salt.

We have discovered that the amine salts of starch half esters can be prepared in a single step by the simultaneous treatment of starch in an aqueous slurry with a dibasic acid anhydride and an amine while maintaining the pH of the reaction mixture at 5-7. This procedure is a simplification of the preparation of the amine salts of starch half esters, and additionally avoids the danger of gelatinization that might occur, as pointed out in U.S. Pat. No. 2,891,947, when the acylation of starch with dibasic acid anhydrides is carried out with the addition of alkali at pH 7 or higher. Even partial gelatinization of the starch may cause filtration and other problems which are avoided by our new procedure.

U.S. Pat. No. 2,891,947 teaches starch acylation in pH ranges of about 1.4 to 5.5 in the presence oflimited amounts of moisture in organic solvent media. Our in vention does not limit the amount of moisture which may be present during acylation of starch with dibasic acid anhydrides in the presence of amines, and does not require the presence of organic solvents. Surprisingly, we have found that the reaction should be carried out in a pH range intermediate between the pH ranges prescribed by the above-mentioned patents, that is in the very narrow range between 5.0 and 7.0. As the pH of the reaction mixture approaches pH 7, the viscosity of a solution of the reaction product increases until it becomes too high and is uncontrollable. Moreover, we have found that the above-mentioned gelatinization tendency of starch at alkaline pH is particularly pronounced if an amine is present. Similarly, poor results have been observed if the pH of the reaction mixture is allowed to drop below about 5.5 prior to the complete addition of the amine. A pH range maintained at about 6-6.5 is normally preferred during the addition of the amine. After the addition of the amine is completed, the pH of the solution is allowed to drop below 6 and is finally adjusted as required to about 3.8-4.8, preferably about 4.1-4.3. The downward adjustment of the pH of the reaction mixture into the final range of 3.8-4.8 is conveniently carried out by the addition of maleic anhydride in slight excess and allowing it to hydrolyze to maleic acid. Other water-soluble acids such as tartaric or hydrochloric acid may also be used for the downward adjustment of the pH.

The effectiveness of our acylation procedure of starch with dibasic acid anhydrides in the presence of tertiary amine is unexpected since tertiary amines not only catalyze the acylation of alcoholic hydroxyl groups, but also the acylation of the hydroxyl groups of water, i.e., they catalyze the hydrolysis of acid anhydride (cf. W. L. Bafna and Gold, J. Chem. Soc. 1953, 1406; V. Gold and E. G. Jefferson Le. 1409); in carrying out the reaction on granular starch suspended in water one might have expected hydrolysis of the dibasic anhydride to repress its reaction with starch.

The preferred temperature range for carrying out the maleation of starch according to this invention is 110F. The reaction may be carried out at lower temperatures albeit at slower rates, or at somewhat higher temperatures at faster rates.

In carrying out our procedure one must keep in mind that our amine salts generally have a lower pasting temperature than the parent starches, particularly at increasing degree of substitution. In order to avoid handling difficulties in the product, the reaction temperature should not approach the pasting temperature of the product more closely than by about l5-20F.

The mother liquors accompanying our products usually contain maleic acid and'amine. Accordingly, product isolated by filtration without washing tends to retain maleic acid and amine. Satisfactory products are obtained after effective filtration without washing, although residual mother liquors may be removed by washing if desired. Excessive washing should be avoided, because it removes amine from the starch half ester-amine combination, and reduces the effectiveness of the combination as a warp size. The loss of amine from the combination by washing indicates that the combination is not highly ionic, because one would not expect amine to be removed from a highly ionic combination by washing.

The viscosity increases observed in the acylation product are believed to be partly caused by diester formation during or following half ester formation when the pH of the reaction mixture is not maintained within the range of 5-7. Half esters of maleic acid and other dibasic acids are known to undergo disproportionation reactions which result in the formation of diester and an equivalent amount of dibasic acid, and it is believed the disproportionation is favored by excess heating and by other less well understood factors. Disproportionation results in cross-linking of the starch, and may cause substantial viscosity increases in their solutions.

In order to obtain products having acceptable and reproducible viscosity characteristics, the pH of the slurries during the following reaction should be kept within the stated ranges. Moreover, excessive drying of the product should be avoided. During the drying process, temperatures in excess of about 225F. should be avoided and about 7-12 percent moisture should be allowed to remain in the product. The solution viscosity of overdried products is usually too high initially and tends to increase further on storage.

When the starch maleation products are prepared outside the prescribed pH range or overdried, the resulting undesirable viscosity increases are erratic and unpredictable. It is, therefore, impractical to apply additional pre-thinning to the starch in an attempt to compensate for such viscosity increases. In addition, acid thinning of the excessively viscous maleation product decomposes the maleyl-amine sizing constituent. Enzymatic thinning of the overly viscous product is no help either, because the product is altered substantially, and this additional step adds considerable processing cost which is unnecessary when the reaction pH range is maintained.

The high warp sizing efficiency of the amine/starch maleate half ester of this invention has been demonstrated with the triethylamine/starch maleate halfester. In the following table replicate experiments on two warp sizing solutions with 65/35 polyester-cotton, 40s count yarn are compared. Solutions la, b and c contained 3 percent wax on the basis of starch with 15 percent of a starch-maleic anhydride-triethylamine product according to this invention, having carboxyl content about 0.3 percent. Solutions Ila and b contained 15 percent of a commercial (and conventional) acetylated warp size starch having about 2% percent acetyl content together with 3 percent wax on the basis of starch, and 5 percent poly(sodium acrylate).

Viscosity Add-on Shed %"cup(sec) (96) Solution la 10.8 12.8 2.3 b 8.5 12.5 2.3 c 6.4 10.9 2.1 Solution Ila 17.5 14.8 3.7 b l6 2.7

Solution viscosity, add-on, and percent shed of solutions la, b and c are distinctly lower than those of solutions Ila and b. Lower add-on means less sizing agent is consumed; the maleation product is more economical in use than the acetylation product. Nevertheless, the product of this invention substantially reduced the shed (by almost one-third). This shed reduction is a substantial contribution to weaving efficiency.

In another test series a comparison was made in sizing efficiency on 65/35 polyester/cotton yarn. In five preparations according to Example 1, shed values ranged from 1.87 to 2.27 percent; the ratios of percent shed/percent size add-on to fiber varied from 0.165 to 0.205. In two control experiments containing wax, commercial acrylic polymer binder (water-soluble commercial sodium salt of a copolymer of acrylic acid and a mixture of alkyl acrylate esters) and conventional warp size starch of the acetate type, shed was 2.81 and 3.72 percent, and the shed/add-on ratios were 0.239 and 0.25 l, respectively.

In numerous weaving trials with a variety of yarns, warp size compositions containing maleated starch made according to Example 1 gave weaving efficiencies superior to conventional starch based warp sizes, and comparable to other much more expensive materials, such as polyvinyl alcohol. The yarns used included wool and polyester/wool blends (/30 and 54/56); blends with higher cotton content (SO/50 polyester/cotton, 25/75 nylon/cotton) and polyester/rayon (65/35high wet modulus rayon).

Additional details are described in Examples 11 and IV.

Suggested formulas for industrial use, comprising warp size starches according to Example 11 are as follows:

A B C Warp size starch, lbs. 400 300 300 Wax, lbs. 12 1O 10 Finish, gallons 300 175 245 Size concentration, 15.0 18.5 14.0 Yarn size content, 14.0 17.6 15.0 Slasher speed, yards per min. 70 75 A: for 65% polyester/35% cotton blend high sley; medium yarn, 22s

8: for65% polyester/35% cotton blend high sley broadcloth, 128 X 72; 50s yarn C: for 50% polyester/50% cotton blend average sley, 72 X 60; 20s yarn.

The carboxyl content of the new warp size starches may vary from as little as about 0.15 percent .to as much as about 3 percent but carboxyl contents in the range of about 0.2 percent to 1 percent are preferred inasmuch as the cost of introducing a higher carboxyl content is usually not warranted by any further improvements in warp sizing performance. The carboxyl content is determined by alkali titration after removal of amine by acid washing.

As has been pointed out above, modified starches may be used for conversion to the warp sizing agents of this invention. Such modifications may be introduced in order to modify and control viscosity characteristics of the warp sizing agents; e.g., a low level of acetylation or a hydroxy-alkylation can have a beneficial effect on viscosity stability of the sizing agent. If amines are used according to this invention, modifying groups such as acetyl or hydroxyalkyl will generally be introduced before the amines. In other cases, one skilled in the art will readily perceive whether or not the sizing group may be introduced prior to the modifying group.

The following examples, in which all parts and percentages are by weight, illustrate the method of making starch based sizing agents by means of maleation of starch in the presence of tertiary amines and the use of such agents for sizing starch. The methods for introducing modifying groups and other sizing groups are known. It is not intended to limit the invention to the details given in these examples.

EXAMPLE I This example describes the treatment of partially thinned corn starch, with maleic anhydride and triethylamine.

A starch slurry (approximately 225 Be. at 60F.) containing parts corn starch was partially thinned (hydrolyzed) with dilute sulfuric acid in the known manner to a gram (0.375 N NaOH) alkali fluidity of 62-66 ml. (measured after neutralization with soda ash to 4.5-5.0 pH).

The resulting slurry was kept at 95-l00F. and purged with nitrogen. A nitrogen atmosphere was maintained during the following operations. The mixture was stirred and its pH adjusted to 6.3-6.5 by the addition of triethylamine.

Molten maleic anhydride (2.0 parts) was added gradually during about 60 min. to the stirred mixture. At the same time that the maleic anhydride addition was started, the separate addition of triethylamine (1.75 parts) was begun at a rate sufficient to maintain the slurry pH at 60-65, as far as possible at 6.3-6.5. The slurry pH was not permitted to exceed 6.5. The maleic anhydride addition was continued after the addition of the amine was complete, and the pH was thereby lowered to 3.3-4.2. Stirring at 95-100F. was continued for six hours after completion of the maleic anhydride addition. Four hours after completion of the maleic anhydride addition, the slurry pH was measured and adjusted to 3.9-4.1 with additional triethylamine or with HCl, as necessary. The reaction mixture was filtered and the filter cake dried to 11-12 percent moisture. Maximum drying temperatures were 175F. during initial, and 225F. during final drying.

It should be noted that maleic anhydride and tertiary amine must not be directly combined as explosive reactions may ensue.

EXAMPLE II This example describes the acetylation of partially thinned corn starch followed by treatment with maleic anhydride and triethylamine.

A starch slurry (approximately 22.5Be. at 60F.) containing 100 parts corn starch was partially thinned with dilute sulfuric acid, as described in Example 1 except that the mixture was neutralized to 6.5-7.0 pH. After neutralization, alkali fluidity was about 65-70 ml.

To the above reaction mixture, soda ash (1.2 parts as an 18 Be. aqueous solution) was added, and the slurry agitated by a starch recycle pump. Vinyl acetate (3 parts) was added rapidly. When the addition of vinyl acetate was completed, the mixture was kept at 95-l00bLF. for 30 minutes.

The slurry pH was next adjusted to the range of 6.5-7.0 with sulfuric acid. The slurry was filtered and thoroughly washed by reslurrying with cool water (below 105F.), and the slurry pH was adjusted to 6.0-6.5 pH as with hydrochloric acid or soda ash solution, as necessary.

The treatment of the slurry with maleic anhydride and triethylamine was then carried out as described in Example 1. Filtration and drying were also carried out as described in Example 1.

EXAMPLE Ill Example I was repeated using 2.0 parts succinic anhydride and 3.27 parts n-tributylamine. The granular succinic anhydride was added in several portions. The granular starch product had 0.01 degree substitution, dry substance basis.

EXAMPLE 1V Example 11 was repeated using 3.75 parts dimethyl laurylamine. The granular starch product had 0.008 degree substitution, dry substance basis.

EXAMPLE V Preparation of Warp Sizing Composition A sizing mixture of the novel composition was prepared as follows: 568 grams of acid modified (60 fluidity), maleated-amine substituted corn starch containing about 0.3 percent carboxyl and 0.096 nonprotein nitrogen derived from triethylamine was slurried in 2 liters of room temperature tap water under agitation. The slurry was agitated for 10 minutes. Steam was injected into the slurry to paste the starch by raising the temperature to 210F. in 20 minutes under control of a cam operated temperature control unit. The resulting paste was maintained at 210F. for 45 minutes. The final volume of the paste was adjusted to 1 gallon. The paste had a viscosity of 50 centipoises (Brookfield viscometer Model RVF Spindle No. l; 20 r.p.m.) at 200F. and a solids of 15.0 percent (determined by sugar refractometer). Eighteen grams of sizing wax (Seycowax C) was added to the pastes 10 minutes before the end of the 45 minute cook period.

Warp Sizing The prepared paste was transferred to the size box of a Model 51 West Point Callaway Slasher and maintained at 204F. by a steam injection coil in the size box. One hundred ends of 40/1 yarn composed of percent Dacron Type 54 polyester and 35 percent combed cotton were sized in one segment forty yards in length. Two additional segments were sized to total 300 sized ends on a shed tester beam. The percent size content of the yarn was 1 1.62 percent.

Shed Testing The shed tester is a device that includes all the working parts of a typical weaving loom except filling yarn insertion. During operation, it is completely enclosed so all fiber and size lost by abrasion can be accurately collected. The 300 ends of sized yarn were processed on the shed tester at the rate of 180 picks per minute until a total of 43,200 picks were completed. The yarn travel was adjusted to 3 inches per minute. The shed was collected from the interior of the machine. The shed weighed 2.12 percent of the weight of the yarn processed during the test. The number of warp end breaks attributable to sizing failure during the run was three.

The procedure was repeated except the size concentration used was 12.0 percent. The wax used remained at 3 percent on the starch weight. The size content of the yarn (add-on) was 10.50 percent. The percent shed loss was 1.87 and the number of warp end breaks attributable to sizing failure was three.

EXAMPLE VI A conventional sizing composition was prepared containing about 15 weight percent of a medium fluidity acetylated corn starch (minimum acetyl content, 2.0 percent), sodium polyacrylate binder (5 percent of starch weight) and sizing wax (3 percent on starch weight) and used in a test identical to the foregoing. The shed loss was 3.51 percent, and the number of warp end breaks attributable to sizing failure was five.

In another set of comparisons, shed losses at more equal add-ons were compared with the same kind of yarn.

Add-On Shed Formula A Acetate Starch (30 fluidity), binder and wax 10.86 3.51 B Acetate Starch (40 fluidity), binder and wax 12.86 3.03 C Acetate Starch (4O fluidity), and wax 12.97 3.59 Warp size starch prepared acc. to Example I and wax 11.62 2.12 Warp size starch prepared acc. to Example 1 and wax 10.90 2.10 Warp size starch prepared acc. to Example land wax 10.50 1.87

The tributylamine starch succinate prepared in Example III performed similarly in the warp sizing test as the triethylamine starch maleate in Example V whereas the dimethyllaurylamine starch succinate prepared in Example IV performed less well.

In conformity with the mode of operation of this invention described before, it is believed that the amines may be linked to the starch through ether groups (e.g., through carboxymethyl ether obtained by reaction of starch with sodium chloroacetate) or through carboxyl groups formed in the starch chain by oxidation (e.g., with sodium hypochlorite).

In general, the usefulness of the new starch derivatives depends upon the hydrophobicity of the substituent. Aside from their usefulness in warp size applications the new compositions are useful as hydrophobic binder and coating components, e.g., in paper and non-woven fabrics, as softening agents and in other ways.

We claim:

1. The method of making an amine salt of a starch half-ester particularly useful as a warp size on synthetic fibers, the steps comprising first making an aqueous slurry of starch, continuously maintaining the temperature of the starch slurry in a range at least about 15F. below the pasting temperature of the starch, adjusting the pH of said slurry to a relatively narrow range between the overall limits of 4-7, continuously agitating said starch slurry while adding dibasic acid anhydride to the starch slurry, simultaneously but separately adding amine to the starch slurry to maintain the pH of the slurry within said relatively narrow range, continuing the addition of said dibasic acid anhydride after the addition of the amine is completed, thereby lowering the pH of said slurry to a pH ranging from 3.3-4.3, continuing the reaction for a period of time after completion of the amine addition, then adjusting the pH to a range up to 4.8 to obtain desired viscosity, and filtering the reaction mixture to obtain a filter cake, and then drying said filter cake to obtain a granular amine salt of a starch half-ester having a carboxyl content in the range of 0.15 to 3 percent by weight and a degree of substitution derived from said dibasic acid anhydride in the range of0.005 to 0.1.

2. The process of claim 1 in which the amine is selected from the group consistin of tertiary amine free of actlve hydrogen inclu mg triethylamlne,

tripropylamine and tributylamine, and the dibasic acid anhydride is selected from the group consisting of maleic, succinic, citraconic, phthalic, and cyclohexene- 1,2-dicarboxylic acid anhydride.

3. The process of claim 2, in which the amine is triethylamine, and the dibasic acid anhydride is maleic Since many embodiments of this invention may be 3 anhydride- 4. The product resulting from the method of claim 1.

5. The product resulting from the method of claim 2.

6. The product resulting from the method of claim 3.

Claims (5)

1. The method of making an amine salt of a starch half-ester particularly useful as a warp size on synthetic fibers, the steps comprising first making an aqueous slurry of starch, continuously maintaining the temperature of the starch slurry in a range at least about 15*F. below the pasting temperature of the starch, adjusting the pH of said slurry to a relatively narrow range between the overall limits of 4-7, continuously agitating said starch slurry while adding dibasic acid anhydride to the starch slurry, simultaneously but separately adding amine to the starch slurry to maintain the pH of the slurry within said relatively narrow range, continuing the addition of said dibasic acid anhydride after the addition of the amine is completed, thereby lowering the pH of said slurry to a pH ranging from 3.3-4.3, continuing the reaction for a period of time after completion of the amine addition, then adjusting the pH to a range up to 4.8 to obtain desired viscosity, and filtering the reaction mixture to obtain a filter cake, and then drying said filter cake to obtain a granular amine salt of a starch half-ester having a carboxyl content in the range of 0.15 to 3 percent by weight and a degree of substitution derived from said dibasic acid anhydride in the range of 0.005 to 0.1.

2. The process of claim 1 in which the amine is selected from the group consisting of tertiary amine free of active hydrogen including triethylamine, tripropylamine and tributylamine, and the dibasic acid anhydride is selected from the group consisting of maleic, succinic, citraconic, phthalic, and cyclohexene-1,2-dicarboxylic acid anhydride.

3. The process of claim 2, in which the amine is triethylamine, and the dibasic acid anhydride is maleic anhydride.

4. The product resulting from the method of claim 1.

5. The product resulting from the method of claim 2.