NO147218B - PROCEDURE FOR THE PREPARATION OF ROAD CONSTRUCTION OF CONCRETE BRONZE - Google Patents

Description

Process for improving the whiteness and receptivity to basic dyes of thermoplastic fibers.

The present invention relates to a

method for improving the whiteness of thermoplastic fibers and at the same time increasing the receptivity of such fibers to basic dyes. In particular, the invention relates to a

■method of improving the whiteness of acrylic polymer fibers during spinning and .

drying of such fibers with the simultaneous improvement of the receptivity to basic dyes of shaped articles consisting of acrylonitrile polymers, copolymers terpolymers and higher interpolymers of acrylonitrile and mixtures of such polymers.

Fibers consisting of acrylonitrile polymers and interpolymers have many very good properties which make them particularly advantageous in the textile industry. Thus, such synthetic fibers have a very good resistance to -washing, wear and tear and the formation of unwanted folds, together with softness, a comfortable "grip" and a very advantageous ability to retain their shape. However, such fibers have a very undesirable property, namely that they do not have the degree of whiteness that is desirable for their use in the textile industry. Most synthetic acrylic fibers get a faint yellowish color tone or color when they are produced, which is very unfortunate. Numerous methods have been proposed which aim to remove this discolouration. Thus, conventional bleaching agents have been used for textile materials, but the use of such has been completely unsuccessful, as such conventional bleaching agents supposedly remove the original initial coloring of the fibers, while these are stable against ultraviolet rays to such an extent that they generally becomes discolored within approx. 2 hours of exposure to such rays. In addition, temperatures of approx. 150° C or higher in the direction of increasing this discoloration of the fibers.

With the help of the present invention, a method is obtained for the production of acrylic fibers with acceptable whiteness and which maintains this improved whiteness when they are exposed to the influence of ultraviolet rays and heat. At the same time, as mentioned above, fibers which have been treated in accordance .with.the.invention,\an improved receptivity to basic dyes.

The characteristic main feature of the invention is that thermoplastic fibers are treated with an aqueous solution of hypophosphoric acid or a mixture of this acid and water-soluble metal salts thereof, in a concentration of 0.01 to 1.0 percent.

Preferably, the underphosphoric acid or its mixture with said metal salts is used in a concentration of 0.1%. to 0.5 percent

Alkali metal salts or alkaline earth metal salts can be used as water-soluble salts of hypophosphoric acid. The pH value of the treatment agent should be kept at 7 or lower, preferably below 4.

The solution of the treatment agent can be supplied to the fibers by spraying, in the final treatment bath using wicks, using rollers or in another suitable way.

The polymeric materials to which the method according to the invention can be applied are materials consisting of polyacrylonitrile, copolymers, including binary or ternary polymers containing at least 80 wt. acrylonitrile in the polymer molecule, or mixtures containing polyacrylonitrile or copolymers comprising acrylonitrile with from 2 to 50% other polymeric materials, so that the mixtures have a polymerized acrylonitrile content of at least 80% by weight. The coated polymers used in the method according to the invention are those which contain at least 80% acrylonitrile and which are generally recognized as fiber-forming acrylonitrile polymers, but the method according to the invention can also be used on polymers which contain less than 80% acrylonitrile . Acrylonitrile polymers containing less than 80 percent acrylonitrile are advantageous for the production of film, coating agents, materials for casting and varnishes.

The polymeric materials can e.g. be a copolymer of 80 to 98 percent acrylonitrile and from 2 to 20 percent. by another

monomer containing the group

and which is copolymerizable with acrylonitrile. Among suitable monoolefin monomers are acrylic acid, α-chloroacrylic acid and methacrylic acid, acrylates, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, methoxymethyl methacrylate, (3-chloroethyl methacrylate and the corresponding esters of acrylic acid and α-chloroacrylic acid, vinyl chloride, vinyl fluoride . N-vinylphthalic acid imide and N-vinylsuccinimide, methylenemalonic acid esters, itaconic acid and itaconic acid esters, N-vinylcarbazole, vinylfuran, alkyl vinylesters, vinylsulfonic acid, ethylene-α,β-dicarboxylic acids or anhydrides and other derivatives thereof, such as diethylcitraconate, diethylmesaconate, styrene, vinylnaphthalene, vinyl-substituted tertiary heterocyclic amines, such as vinylpyridines and alkyl-substituted vinylpyridines, e.g. ks. 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, 1-vinylimidazole and alkyl-substituted 1-vinylimidazoles, such as 2-, 4- or 5-methyl-1-vinylimidazole, as well as other polymerizable materials containing the group

The polymeric materials can further be ternary or higher interpolymers, e.g. products obtained by interpolymerization of acrylonitrile and two or more other monomers of those mentioned above. The ternary polymers can preferably be polymers of acrylonitrile, methacrylonitrile and 2-vinylpyridine. Other preferred ternary polymers contain 80 to 98 percent of acrylonitrile, from 1 to 10 percent of a vinylpyridine or a 1-vinylimidazole and from 1 to 18 percent of another substance such as methacrylonitrile or vinyl chloride.

The polymeric materials can also be mixtures of (1) a polyacrylonitrile or a binary interpolymer from 80 to 99 percent acrylonitrile and from 1 to 20 percent of at least one other substance containing the group

with (2) from 2 to 50 wt. of a mixture of a copolymer of from 10 to 70 percent acrylonitrile and from 30 to 90 percent of at least one other polymerizable monomer containing groups

When the polymeric material is a blend, it is preferably a blend of a copolymer of 90 to 98 percent acrylonitrile and from 2 to 10 percent of another mono-olefin monomer, such as vinyl acetate, with a sufficient amount of a copolymer of from 10 to 70 percent acrylonitrile and from 30 to 90 percent of a vinyl-substituted tertiary heterocyclic amine, such as vinylpyridine or 1-vinylimidazole, so that a dyeable material is obtained with a total content of vinyl-substituted tertiary heterocyclic amine of from 2 to 10 percent calculated on the weight of the mixture.

In the following, some embodiments of the invention are described as examples. In these, quantity ratios are stated in weight units. when not otherwise mentioned.

Example 1.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate and a conventional solvent was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The filaments obtained were stretched, washed (with "20 wash roll wraps") and then passed through 2000 ml of a conventional finishing bath to which was added 40 ml of 50 per cent hypophosphoric acid. The fibers were then dried and their color and whiteness determined. They showed 2.2 purity units and 85.1 brightness units ("brightness units") measured by reflection in a General Electric Spectrophotometer. From these values for purity and lightness, the whiteness was calculated to be 89.8.

Example 2.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The filaments obtained were stretched, washed (with "8 wash roll wraps") and then passed through 2000 ml of a conventional finishing bath to which was added 40 ml of 50% hypophosphoric acid. The fibers were then dried. As determined in Example 1, their purity was found to be 2.5, brightness 84.7 and whiteness 87.5.

Example 3.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The fibers were then stretched, washed (with "20 wash roll wraps") and passed through 2000 ml of a conventional finishing bath which did not contain additives according to the invention. The fibers were then dried. By determinations as indicated in Example 1, their purity was found to be 5.8, brightness 81.6, of which the brightness was calculated to be 45.

Example 4.

The procedure was exactly as indicated in example 3, with the exception that normal washing was used ("6 wash roll wraps"). By determinations as indicated in example 1, the purity of the fibers was found to be 5.5, the lightness 81.7, of which the whiteness was calculated to be 47.5.

Example 5.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The filaments obtained were stretched, washed (with "20 wash roll wraps") and passed through 2000 ml of a conventional finishing bath to which was added 8 ml of 50% hypophosphoric acid. The fibers were then dried. By determination as indicated in Example 1, their purity was found to be 3.2, their brightness 85.2 and whiteness 82.9.

Example 6.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The filaments obtained were stretched, washed (with "6 wash roll wraps") and passed through 2000 ml of a conventional finishing bath to which was added 8 ml of 50% hypophosphoric acid. The fibers were then dried. By determinations as indicated in Example 1, the purity of the fibers was found to be 3.2, their brightness 84.7 and their whiteness 82.6.

Example 7.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath. The filaments obtained were stretched, washed (with "20 wash roll wraps") and then passed through 2000 ml of a conventional finishing bath to which was added 40 ml of 50% hypophosphoric acid. The fibers were then dried. As determined in Example 1, their purity was found to be 1.9, their brightness 84.1 and their whiteness 90.6.

Example 8.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The obtained filaments were stretched, washed (with "6 wash roll wraps") and then passed through 2000 ml of a conventional finishing bath to which was added 40 ml of 50% hypophosphoric acid and 4 grams of sodium hypophosphite. The fibers were then dried. By determination as indicated in Example 1, their purity was found to be 2.3, their brightness 86.0 and whiteness 89.8.

Example 9.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The obtained filaments were stretched, washed (with "20 wash roll wraps")

and then passed through 2000 ml of a conventional final treatment bath to which 8 ml of 50% hypophosphoric acid and 20 grams of sodium hypophosphite had been added. The fibers were then dried. As determined in Example 1, their purity was found to be 3.9, their brightness 85.3 and their whiteness 77.0.

Example 10.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The obtained filaments were stretched, washed (with "6 wash roll wraps")

and then led through 2000 ml of a conventional final treatment bath to which 8 ml of 50 per cent hypophosphoric acid had been added as well as. 20 grams of sodium hypophosphite. By determination as indicated in Example 1, the purity of the filaments was found to be 3.9, their brightness 85.5 and their whiteness 76.5. j Example 11.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The fibers were then stretched, washed (with "20 wash roll wraps") and then

on led through 2000 ml of a conventional finishing bath which had been added 8

ml of 50% hypophosphorous acid and 4 grams of sodium hypophosphite. The fibers were then dried. In the case of provisions as stated in exem-

pel 1 their purity was found to be 3.5, their brightness 85.6 and their whiteness 80.5.

Example 12.

A spinning solution containing 93% acrylonitrile and 7% vinyl acetate was extruded into filaments in a conventional coagulation bath consisting of water and solvent. The obtained filaments were stretched, washed (with "6 wash roll wraps")

and then passed through 2000 ml of a conventional finishing bath to which 8 ml of 50% hypophosphoric acid and 4 grams of sodium hypophosphite had been added. The filaments were then dried. As determined in Example 1, their purity was found to be 3.9, their lightness 36.0 and their whiteness 76.8.

Example 13.

A spinning solution containing 93 cheese. acrylonitrile and 7% vinyl acetate were extruded into filaments in a conventional coagulation bath consisting of water and solvent. The obtained filaments were stretched, washed (with "20 wash roll wraps")

and then passed through 2000 ml of a conventional finishing bath which did not contain additives according to the invention. The obtained filaments were dried and dyed with "Sevron Blue 2G, C.I. Basic Blue 22" in a conventional manner. A known amount of dye was added to the dye solution and the amount of dye that remained after dyeing,

was determined. It was found that the uptake of the basic dye was 3.7 per cent.

Example 14.

A spinning solution containing 93 Dst. acrylonitrile and 7% vinyl acetate were extruded into filaments in a conventional coagulation bath consisting of water and solvent. The obtained filaments were stretched, washed (with "20 wash roll wraps")

and then passed through 2000 ml of a conventional finishing bath which was allowed 4 ml of 50% hypophosphoric acid and 20 grams of sodium hypophosphite. The filaments were then dried and stained with "Sevron Blue 2G. C. I. Basic Blue 22". When determined in the same way as in example 13, it was found that the uptake of this basic dye was 6.0 percent.

Thus, with the additives according to the invention, it is not only possible to obtain whiter fibers and filaments than was previously possible, but also an almost 100 percent increase in the absorption of basic dyes is achieved. The fibers also get an improved dyeability in another way, as the improved whiteness also gives better color when the fibers are subsequently dyed.

Claims (6)

1. Process for improving the whiteness of thermoplastic fibers, especially acrylic fibers. and at the same time increase the receptivity of the fibers to basic dyes, characterized by treating the fibers with hypophosphoric acid or mixtures of hypophosphoric acid with water-soluble metal salts of this acid, in concentrations from 0.01 percent to 1 percent. 2. Application of the method according to claim 1 on fibers containing at least 80% of acrylonitrile and up to 20% of another monoolefin monomer which is copolymerizable with acrylonitrile. 3. Use as stated in claim 2, characterized in that the fibers consist of 93% acrylonitrile and 7% vinyl acetate. 4. Use as stated in claim 3, characterized in that the treatment solution's pH value is below 7. 5. Application as stated in claim 4, characterized by that treatment the agent is a mixture of hypophosphoric acid and potassium or sodium hypophosphite. 6. Use as stated in claim 4, characterized in that the treatment agent is a mixture of hypophosphorous acid and calcium hypophosphite.