US2869435A

US2869435A - Process and product

Info

Publication number: US2869435A
Application number: US557096A
Authority: US
Inventors: Sands Seymour
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1956-01-03
Filing date: 1956-01-03
Publication date: 1959-01-20
Anticipated expiration: 1976-01-20
Also published as: DE1078427B; NL213412A; CH351166A; FR1170765A; GB847617A

Description

Filed Jan. 3, 1956 INVENTOR SEYMOUR SANDS BY Maw ATTORNEY I PROCESS PRODUCT Seymour Sands, New Castle, DeL, assignor to E. I. du

Pont de Nemours and Company, Wilmington, Del., a

corporation of Delaware Application January 3, 1956, Serial No. 557,096

Claims. (Cl. 92-3) This invention relates to a novel and useful process and product. More particularly it is concerned with a process of suspending a fibrous material in anaqueous medium and a composition employedasa coating for the fibrous material in the said process. 7

In attempting to obtain uniform suspensions of fibrous materials in aqueous media by mixing, beating and the like, particles frequently tend to cling together, forming clusters. This is particularly true when an attempt is made to form an aqueous suspension of synthetic fibers. These fibers being generally hydrophobic resist wetting with water. The formation of uniform suspensions is imbearing the gelatinous coating is thereafter dried, then: cut to size and is finally added to the body of water in which-it forms an aqueous suspension.

The following examples are cited to illustrate the inven tion. They are not intended to limit it in any way.

Example I An uncrimped 330,000 total denier tow of polyhexamethylene adipamide yarn made up of 6 denier per filament fibers is passed through an aqueous solution containing 3% by weight of lauryl pyridinium chloride. Immediately thereafter it is passed through an aqueous solution containing 3% by weight of sodium salt of lauryl sulfate. The tow is then dried in air and cut into A inch lengths. The fibers so formed are dropped onto the surface of water in a vessel being slowly stirred with a laboratory mixer. A 0.2% by weight suspension of fibers portant in the manufacture of water leaves, batts and the like, which may thereafter be processed into paper and paper-like structures.

It is an object of the presentinvention to provide a novel and useful gelatinous reaction product of a watersoluble salt of a long chain aliphatic sulfate with a watersoluble salt of a long chain aliphatic quaternary am-. monium compound. I q

Another object is to provide a process for the production of the reaction product recited above.

A further object is to provide a fibrous product bearingon its surface a coating of the reaction product recited above. 4

A still further object is to provide a process of ms pending fibrous materials in an aqueous medium to provide a uniform distribution therein. 1

These and other objects will become apparent in the course of the following specification and claims.

11 accordance with the present invention a suspension of fibrous material in water is provided by a process which comprises the steps of coating the said material with the gelatinous reaction product of a water-soluble salt of a long chain aliphatic sulfate and a water-soluble salt of a long chain aliphatic quaternary ammonium compound, drying the coted material and thereafter adding the said dried coated material to a water suspending medium. The gelatinousreaction product is formed by combining the two reactants in approximately equimolecular proportions in the presence of water. It may then be applied in the gelatinous state to the fibrous material from an aqueous suspension. Alternatively the gelatinous reaction product defined may be formed directly upon the fibrous material by suspending. the said material in first one reaction component and then the'second reaction component. After the fibrous material is coated with the gelatinous reaction product identified above, it is dried prior to suspension of the fibers in water. i

The invention will be more readily understood by reference to the drawing. 7

The figure is a flow sheet'showing the preparation of an aqueous suspension of fibrous material. As shown in the figure the raw fibrous material may be coated with the gelatinous reaction product (AB) or it may be coated successively with first one reaction component (A) and then the other reaction component (B). The fibrous material in water, free of fiber clusters forms readily.

When the suspension is used to make paper, either on a hand-sheet, mold or on a continuous paper machine, the paper obtained is free ofclumps and uniform in thickness. A control sample of paper formed without the use of the gelatinous reaction product is lumpy due to fiber clumps and displays poor uniformity.

Example I] An aqueous solution containing 3% by weight of lauryl pyridinium chloride in water and an aqueous solution containing 3.5% of the sodium salt of lauryl sulfate are slowly mixed with mild agitation. A gelatinous precipitate forms. An uncrimped 385,000'total denier towof polyethylene'terephthalate yarn made up of 3 denier per filament fibers is passed through the suspension formed; It is then allowed to dry in air at room temperature. The coated dried tow is cut to lengths of A inch and the. resulting staple is dropped into water withmild agitation. The fibers disperse uniformly without cluster formation.

In the following examples various coating materials are applied to the yarn described in Example I, employing the technique of Example '1. Each coating material is applied from an aqueous solution or'suspension contain ing 3% by weight of the indicated coating material. In each of Examples III, IV and VI the fiber picks up a 3% by weight coating based on the weight of the dry fiber.

When. theconcentration of coating'material in Example V is raisedso as to produce a fiber-bearing 50% by weight of the sodium salt of lauryl sulfate based on the weight of the dry fiber, cluster formation still occurs.

Example VII A tow of polyhexamethylene' adipamide'yarn is passed through an aqueous suspension containing 4% by weight of the gelatinousreaction product of lauryl pyridinium chloride and the sodium salt of lauryl sulfate. After drying, the tow is cut' into inch length staple. 3 grams of the coated fiber is suspended by being gently stirred into 4 liters of water. The resulting uniform suspension is filtered over an 8 inch by 8 inch square of meshscreen to form a hand sheet. After drying, the hand sheet is dipped into an aqueous dispersion containing 4% of N-j methoxymethyl polyhexamethylene adipamide having 2,869,435- Patented Jan. 20, .1959

The properties of each of the paper-like products produced from the above processes are reported below. The test results are obtained by following the procedures in TAPPI Standards.

Untreated Treated Fibers Fibers Weight, grams 4. 3. 8 Percent Amide binder 24. 6 25 Tear, grams 512 1, 372 Burst, p. s. i./g 18 26.3

The gelatinous reaction product employed in the coating of the fibrous materials is produced by slowly mixing with the minimum of agitation and in the presence of water the water-soluble salt of a long chain aliphatic sulfate with the water-soluble salt of a long chain aliphatic quaternary ammonium compound. A combination of reactants which is too rapid or accompanied by agitation which is too violent promotes the formation of a granular or crystalline precipitate which is not effective in the process of the present invention. The mixing of the reaction components may be performed by adding one to the other in a continuous stream with just suficient agitation to promote thorough dispersion of each reactant in the reaction medium. In general the addition is performed at room temperature although the use of a particular temperature is not critical. It is preferred that the reactants be combined in essentially equiinolecular proportions. The solution in which the gelatinous reaction product is formed is of practical effectiveness when it contains more than at least about 2% of reaction product. The use of aqueous suspensions containing 3 to 12% 6f the gelatinous reaction product are preferred. At substantially higher concentrations the increase in viscosity of the bath makes difficult its application as a coating to the fibrous materials.

Usually the gelatinous reaction product is formed in situ upon the surface of the fibreus material. The material is coated first with one reactant and then with the other. The reactants are applied from aqueous solution containing more than at least about 2% of reactant. The order in which the reactants are placed upon the fibrous materials is not critical. Regardless of method of application, it is preferred that the dried, coated fibrous material bear from about 3% to about by weight of the coating.

Typical of the gelatinous precipitates which are useful for practicing this invention are those formed by reacting lauryl pyridinium chloride with sodium lauryl sulfate, cetyl pyridinium chloride with sodium lauryl sulfate, octadecyl trimethyl ammonium chloride with sodium lauryl sulfate, lauryl pyridinium chloride with sodium decyl sulfate, lauryl pyridinium chloride with sodium octyl sulfate, lauryl pyridinium chloride. with potassium lauryl sulfate, and sodium lauryl sulfate with the dimethyl dialkenyl quaternary ammonium compound (available fronrRohm' and Haas Company, Philadelphia, Pa, as EXP-QUAT. 3104) having the formula In place of a single alkyl sulfate or quaternary ammonium compound for making the gelatinous precipitates for use in this invention, mixtures fnay beused of two or more compounds having a different number of carbon atoms in the alkyl chains. For example, commercially available mixtures are suitable such as the sodium salt of the sulfuric acid ester of technical grade lauryl alcohol (a mixture of normal straight chain alcohols of even numbers of carbon atoms from 8 to 16, inclusive, with lauryl alcohol predominating). It is preferred to prepare the gelatinous precipitates from one or more alkyl or alkenyl sulfates having 8 to 18 carbon atoms and from alkyl or alkenyl quaternary ammonium compounds having 8 to 18 carbon atoms in the alkyl or alkenyl groups. Mixtures of alkyl and alkenyl groups in the same precipitate are also useful. Any Water soluble salt of the reactants may be employed. The alkali metal salts, particularly sodium and potassium, are preferred.

The gelatinous reaction product, or the reactants to form the said product may be applied from aqueous suspension to the fibrous or fiber-forming materials by any conventional method such as dipping, spraying, wicking, padding by feed roll and the like.

After the fibrous or fiber-forming structure has been coated with the suspension of gelatinous reaction product it is thereafter dried, The drying operation may be preceded by centrifugal extraction, wringing out by passing through squeeze rollers, or the like, to remove excess liquid. The drying operation is conveniently performed by permitting the coated structure to remain at room temperature for a period sufiicient to permit evaporation of liquid from the coating. The operation may be hastened by employing elevated temperatures below those which will cause decomposition of the gelatinous reaction product. Reduced pressure may also be used. After being dried, the structure is in a stable form and may be shipped or stored for an indefinite period of time without losing its ability to be readily suspended in water.

To suspend the fibrous material in water, the dried structure is dropped upon the surface of the agitated, suspending medium. Commercial mixing equipment and the like may be employed effectively. While the suspending medium may be water, as much as about 50% of the water may be replaced by other polar solvents such as ethyl alcohol, acetone and the like. Furthermore, minor quantities of other substances may be present such as dyes and the like.

Neither the length nor the nature of the fibrous material suspended is critical. In general, it is preferred that the fibrous particles be between about A to about /2' inch in length. Furthermore the process is particularly valuable in dispersing hydrophobic synthetic linear polymer fibers. Such hydrophobic fibers, well known in the art, include those formed from polyamides, polyesteramides, polyureas, polyurethanes, copolyamides, polyesters, polyethers, acrylic polymers and copolymers (e. g., polyacrylonitrile), polyethylene, polyetrafiuoroethylene, polychlorotrifluoroethylene, polyvinylidene chloride and copolymers of vinylidene chloride. Other fibers which may be dispersed in accordance with this invention include those of regenerated cellulose, cellulose acetate, cotton, spun glass, wood pulp, and the like.

The process and products of the present invention are particularly useful in the preparation of liquid suspension of fibrous materials employed in the formation of batts and Water-leaves, particularly Where the batt or water-leaf is formed on a moving screen such as upon the Fourdrinier Machine. Thus the process may be employed as a step in the manufacture of paper and paper-like products from synthetic fibers. Typical of such processes is that described in United States application No. 505,040. Such synthetic papers are useful for the preparation of maps and charts, tracing papers, stencil papers, punch cards, filter papers, and a variety of other applications requiring durable, chemically-resistant papers.

The fibrous material to be coated in accordance with this invention may comprise waste fibers occurring from textile spinning and processing operations, such as fioc, cuttings, ends and the like which may be subsequently combined into a rope, tow or continuous yarn before application of the gelatinous reaction product,

Contrary to agents that but temporarily disperse fibers and do not remain on the fibers with continual aqueous processing, the gelatinous reaction products of this invention, when applied to fibers as taught herein even permit redispersal of these fibers, including fibers from paper made therewith.

Many modifications will be obvious to those skilled in the art without a departure from the inventive concept.

What is claimed is:

1. A process of suspending a fibrous material in an essentially aqueous medium which comprises coating the said fibrous material with a gelatinous reaction product of a water-soluble salt of a long chain aliphatic sulfate and a water-soluble salt of a long chain aliphatic quaternary ammonium compound, the said gelatinous reaction product being formed by gently combining substantially equimolecular proportions of the said sulfate and said quaternary ammonium compound in the presence of water, and thereafter drying the said fibrous material bearing the said gelatinous reaction product and dropping the said dried, coated fibrous material upon the agitated surface of the said aqueous medium.

2. An article of manufacture comprising a fibrous material bearing on its surface a dried coating resulting from the drying of a gelatinous reaction product of a water-soluble salt of a long chain aliphatic sulfate and a water-soluble salt of a long chain aliphatic quaternary ammonium compound, the said gelatinous reaction product being formed by gently combining substantially equimolecular proportions of the said sulfate and the said quaternary ammonium compound in the presence of water.

3. The article of claim 2 wherein the fibrous material is a hydrophobic synthetic linear polymer fiber.

4. The article of claim 2 wherein the fibrous material is polyhexamethylene adipamide.

5. The article of claim 2 wherein the fibrous material is polyethylene terephthalate.

6. The article of claim 2 wherein the gelatinous reaction product is formed from a water-soluble salt of a long chain aliphatic quaternary ammonium compound and the sodium salt of lauryl sulfate.

7. The article of claim 2 wherein the gelatinous reaction product is formed from a water-soluble salt of a long chain aliphatic sulfate and lauryl pyridinium chloride.

8. The article of claim 2 wherein the gelatinous reaction product is formed from lauryl pyridinium chloride and sodium salt of lauryl sulfate.

9. The article of claim 2 wherein the gelatinous reaction product is formed from lauryl pyridinium chloride and the sodium salt of decyl sulfate.

10. The article of claim 2 wherein the gelatinous reaction product is formed from octadecyl trimethyl ammonium chloride and the sodium salt of lauryl sulfate.

Katzman Aug. 31, 1943 Niederl Aug. 31, 1954 UNITED STATES PATENT OFFICE Certificate of Correction Patent No. 2,869,435 January 20, 1959 Seymour Sands It is hereby certified that error appears in the printed specification of the above numbered atent requiring correction and that the said Letters Patent should read as correcte below.

Column 1, line 51, for coted read -coated-; column 2, line 40, for Example I read -Example 11-.

Signed and sealed this 28th day of April 1959.

[sun] Attest: T. B. MORROW, ROBERT C. WATSON, Attracting Oflioer. Gammz'ssz'oner of Patents.