EP2160489B1 - Method for preventing yellowing - Google Patents

Description

The invention relates to highly yellowing-resistant polyamide-containing materials having surface finish containing carbodihydrazide, a method of finishing, and the use of appropriately prepared polyamide-containing materials.

Polyamides have a sufficiently high weathering and age resistance for a variety of applications. If desired, in outdoor applications by a special coloring such as carbon black, the durability can be further increased.

Dyeing with soot easily avoids the problem of yellowing, which frequently occurs in plastics - but does not eliminate it. This becomes particularly important if one is not interested in a very dark color of the finished plastic part. In such cases, a yellowing, caused either by oxidative aging processes or even by the thermal treatment during the manufacturing process is negatively noticeable.

A typical thermal treatment process in this context is thermosetting, in which the product in question is subjected to a heat treatment with hot water, steam or dry heat and thus shrinks, whereby a subsequent undesirable dimensional change is prevented. Temperatures of 200 ° C and above are quite common here.

Another method is the molding in which the materials used are brought into a corresponding shape by the action of heat by a (press) tool (that is, by contact heat). This method is used, for example, in the production of brassieres.

The yellowing does not arise here only with untreated or optically brightened polyamide-containing material, which is usually yellow-white or milk-white depending on the type.

Even with colored polyamide-containing material - a coloring is usually achieved with acid or metal complex dyes - this problem occurs. For colored materials, the yellowness changes the original color shade in an undesirable manner.

In addition to yellowing in the course of thermofixing or Moldens also various aggressive compounds such as nitrogen oxides (NOx), ozone or chlorine-containing oxidizing agents exert a negative impact on the weathering or age resistance of polyamide-containing materials.

Therefore, in order to suppress this problem of yellowing, various auxiliaries have been developed. In this context, it should be particularly noted that some textiles, such as brassieres or stockings, are worn directly on the skin and any chemicals used after the application must have sufficient skin compatibility. Even with carpets, for example, a health safety of the chemicals used, since direct skin contact can also take place here.

DE 19 631 381 A1 discloses cellulosic textile materials provided with an aqueous solution containing carba hydrazide. Carbohydrazide is used as a discoloration inhibitor.

EP 0 436 470 B1 describes in this connection a photochemical stabilization of dyed polyamide fiber materials by the use of various complexes of bisazomethines, acylhydrazones, semicarbazones or thiosemicarbazones of aromatic carbonyl compounds with copper as the central metal. The use of the toxic heavy metal copper, however, makes corresponding textile auxiliaries not only environmentally friendly but also health-friendly aspects of concern.

In JP 60-81370 describes a process for treating textile products of polyamide fibers or polyamide fiber blends which have been dyed with acidic or metal-containing dyes. The thus dyed textile products are treated with an antioxidant from the group of carbazides or hydrazines, in particular 1,6-hexamethylene bis (N, N-dimethylsemicarbazide) and adipic dihydrazide [ADH].

WO 2006/045721 A1 describes predominantly dicarboxylic acid bis-hydrazides, and of these in particular ADH, for improving the aging stability of undyed, optically brightened or natural or synthetic polyamide fiber materials dyed with reactive or disperse dyes, with the exception of metal complex dyes.

A disadvantage of the last two methods is in particular the fact that for a sufficient yellowing inhibition a relative large amount of textile adjuvant must be used. From the relatively low water solubility of the excipient, there is a further limitation.

The object of the present invention was therefore to provide a more effective antioxidant for yellowing inhibition. Furthermore, the antioxidant of the invention should have much lower environmental and / or harmful properties. Of course, both factors are mutually dependent, because an increased effectiveness implies the use of a lower amount of the antioxidant, which generally results in a significantly lower environmental and / or health burden.

In a first embodiment, the object underlying the invention is solved by a polyamide-containing material having a surface finish containing carbodihydrazide [CDH].

For the purposes of the present invention, surface finishing means a refining of the material in question, in which case the CDH, in contrast to a surface coating, may also be on the inner surface of the material (caused, for example, by diffusion of the CDH under the equipment conditions).

Surprisingly, it has been found that the yellowing inhibition is in some cases exceeded by the use of CDH compared to the current industry standard ADH.

It is also particularly unexpected that such materials, whose surface finish comprises this relatively small molecule with only one carbon atom but four nitrogen atoms, do not cause skin irritation to OECD 404 or sensitization to OECD 406.

For the purposes of the present invention, the polyamide-containing material need not necessarily be an untreated or undyed material. It is also quite possible that it is an optically brightened material or colored with reactive, acid, disperse or metal complex dyes.

Preferred optical brighteners include the following compounds: stilbene-based compounds, especially alkylation products of 4,4'-diaminostilbene-2,2'-disulfonic acid; Compounds in which two heteroaromatic radicals are linked to one another via an ethylene bridge; Coumarin derivatives, in particular having an amino group or an N-heterocycle instead of the amino group; 1,3-diphenyl-2-pyrazolines; Naphthalimides, especially N-methyl-4-methoxynaphthalimide; Compounds containing a fused aromatic and a heteroaromatic, in particular 2,4-dimethoxy-6- (1'-pyrenyl) -1,3,5-triazine.

Preferred dyes are common dyes for polyamides, especially acid and metal complex dyes.

The polyamide-containing material may contain not only natural polyamides, in particular wool and / or silk, but also synthetic polyamides.

Examples of synthetic polyamides according to the present invention are: polyamide [PA] 4, PA 5, PA 6, PA 11, PA 12, PA 6.6, PA 6.10, PA 6.12, PACM 12, polyaramids such as Nomex and Kevlar, copolyamides such as PA 66/6 and PA 11/12 and block copolymers of polyamides and other polymers, in particular polyethers.

Other constituents of the polyamide-containing material are, in addition to polyamides, other polymers, in particular polyesters, polysaccharides, in particular cotton and / or viscose, polyurethanes and / or polyolefins, and also auxiliaries and / or effect substances customary for polymers, such as, for example, antistats, colorants, flame retardants, fillers Nucleating agents, pigments, reinforcing fibers and / or plasticizers possible.

The polyamide-containing material according to the invention can be present in the form of fibers, nonwovens, mesh, woven or knitwear and, as such, can also be further processed into secondary products.

In a second embodiment, the object underlying the invention is achieved by a process for finishing surfaces of polyamide-containing material, which comprises contacting the carbodihydrazide dissolved or dispersed in a liquid with the surface and subsequently removing the liquid ,

The carbodihydrazide solution or dispersion can be brought into contact with the surface by the exhaustion or, in particular, by padding process (also known as padding). The padding process offers in comparison to the exhaust especially under Environmental aspects have great advantages, since it usually requires less solvent. In addition, it also ensures a more homogeneous application.

The carbodihydrazide can be applied in the process according to the invention before staining or optical brightening. However, it is preferred if this application step is followed by a possible lightening and / or coloring, since only then is the antioxidant used optimally utilized.

As a solvent or dispersant for the carbodihydrazide is used in the process according to the invention advantageously water. Not only does water have high solubility for CDH and the other common additives contained in the liquor, it also has the advantage of high environmental compatibility.

The amount of CDH in the liquor should be adjusted to a range of 0.1 g / L to 20 g / L, in particular from 0.5 to 10 g / L. Lower concentrations have the disadvantage that the CDH-containing liquor would have to be applied several times to the polyamide-containing material in order to achieve the desired efficiency. Higher concentrations are not required for reasons of high efficacy.

In addition to carbodihydrazide, the liquor used may contain other customary process or effect chemicals, in particular wetting agents, plasticizers, oleo and / or hydrophobizing additives or thickeners.

After the application of the carbodihydrazide, a heat-setting or molding step may be followed, in which the antioxidant action of the carbodihydrazide is utilized. It is possible that the fleet mainly removing solvents and / or dispersants in the course of these thermal processing steps to remove what is of course favored insofar as can be reduced in this way, the number of required process steps. However, the solvent and / or dispersant can also be removed beforehand in a separate step.

Another embodiment of the present invention is the use of a solution or dispersion containing a carbodihydrazide as a textile auxiliary.

In particular, it has been found that CDH-treated textiles based on polyamide have a very high stability in the yellowing inhibition against thermal influences and / or oxidizing agents. Under thermal influences are here in particular treatment method of polyamide-containing materials to understand, which are carried out at higher temperatures, such as thermosetting or Molden. Oxidizing agents are to be understood as meaning in particular nitrogen oxides, ozone or chlorine-containing oxidizing agents.

embodiments

In the examples below, the degrees of whiteness are given in Berger units.

Example 1: Treatment of untreated polyamide

• Beispiel 1.A) für 45 s bei 200 °C thermofixiert oder im
• Beispiel 1.B) für 45 s bei 210 °C gemoldet

Rezeptur 1 2 3 4 5 6 7 8 9 ADH (Vergleichsbeispiel) g/L 1 2 4 8 CDH (erfindungsgemäß) g/L 0, 25 0,5 0 1 2 Weißgradmessung nach Trocknen 80 80 80 80 80 80 80 80 80 1.A) nach dem Thermofixieren 48 53 65 66 66 67 71 75 77 1.B) nach dem Molden 43 50 61 63 64 55 57 67 67 An undyed knitted fabric PA 6.6 was padded with an impregnating solution at 100% liquor pickup and dried for 30 s at 120 ° C, then in

• Example 1.A) heat-set at 200 ° C for 45 s or im
• Example 1.B) for 45 s at 210 ° C gemoldet

recipe 1 2 3 4 5 6 7 8th 9 ADH (comparative example) g / L 1 2 4 8th CDH (according to the invention) g / L 0, 25 0,5 0 1 2 Whiteness measurement after drying 80 80 80 80 80 80 80 80 80 1.A) after thermofixing 48 53 65 66 66 67 71 75 77 1.B) after Molden 43 50 61 63 64 55 57 67 67

Example 2: Treatment of optically brightened polyamide

Polyamide 6.6 knit fabric was lightened at a liquor ratio of 1:10 with 1.0% Tuboblanc® MA. The pH was adjusted to 4 with acetic acid, the treatment was carried out at 95 ° C and 30 minutes. Thereafter, rinsed hot and cold and dried at 120 ° C.
Subsequently, the pad at 100% liquor pickup was treated with the stated amount of antioxidant, the pH was adjusted to 5 with acetic acid. It was dried again at 120 ° C. After thermofixing, basic white [GW] and fluorescence [F] are assessed. recipe 1 2 3 4 5 6 7 8th 9 ADH (comparative example) g / L 2 2 2 CDH (according to the invention) g / L 1 1 1 Whiteness measurement GW after drying 77 77 77 77 77 77 77 77 77 F after drying 76 76 76 76 76 76 76 76 76 2.A) GW after heat-setting 190 ° C / 45 s 62 70 74 2.A) F after thermofixing 190 ° C / 45 s 64 73 75 2.B) GW to Molden 210 ° C / 45 s 48 67 74 2.B) F to Molden 210 ° C / 45 s 51 69 74 2.C) GW to Molden 220 ° C / 45 s 25 61 72 2.C) F to Molden 220 ° C / 45 s 32 64 70

Example 3: Treatment of colored polyamide (Molden)

Polyamide 6.6 knitwear was dyed at a liquor ratio of 1:10 with acid dyes. At the beginning of cold 2 g / L Sarabid EP and 0.5 g / L Meropan EF were initially added after 10 min 0.02% of a Bezanyl ^® -Säurefarbstoffes, after a further 10 min at 2 ° C / min to 98 ° C heated , Treated at this temperature for 30 minutes, then cooled to 60 ° C. at 2 ° C./min and rinsed.

As dyes Bezanyl ^® Red E-3G 200 Bezanyl ^® Blue E2R 200 Bezanyl ^® Violet FB or Bezanyl ^® Orange N-GR were used.

After drying at 120 ° C were 0.5, 0.75 or 1 g / L CDH and applied as Comparative Example 1 or 2 g / L ADH in the pad at 100% liquor pickup, dried at 120 ° C and at 210 ° C respectively 30, 60 or 120 s gemoldet.

Result:

ADH and CDH worked very efficiently compared to the samples without antioxidant, 1 g / L ADH improved the result, good results were obtained only with 2 g / L ADH or CDH according to the invention already at 0.5 to 0.75 g / L , 1 g / L CDH worked best.

Example 4: Treatment of dyed polyamide (thermosetting)

The treatment was carried out analogously to Example 3, but instead of Moldens at 200 ° C and 210 ° C in each case 30 or 60 s heat-set.

Result:

With the hydrazides, the color change was well inhibited. 1 g / L CDH scored the same, sometimes even slightly better results than the comparative example with 2 g / L ADH.

Example 5: Thermofixing of polyamides and subsequent dyeing

The treatment was carried out analogously to Example 4, but first the antioxidant was applied, then heat-set and dyed at the end.

The result reflected the same tendency as in Example 4, 1 g / L of CDH was comparable in effect or better than 2 g / L of ADH.

Example 6: NO _x -Vergilbung

A product of 40% of PA 6/60% elastane ^® with a base White of 81 Berger units was padded with antioxidant at 50% wet pickup, and once adjusted without pH adjustment and once with citric acid to a pH of 5.5 was then dried at 120 ° C each.
The NO _x fastness was tested according to EN ISO 105-G01 "NO _x gasification heavy" and assessed by gray scale (1 worst, 5 best). recipe 1 2 3 4 5 6 7 8th 9 ADH (comparative example) g / L 10 20 10 CDH (according to the invention) g / L 10 1 5 10 pH adjusted to 5.5: x x x x x NO _x gasification heavy grading 2 2-3 3 4 3 3-4 3-4 4 4-5 Result: CDH was many times better than ADH.

Example 7: Storage stability and efficacy of aqueous CDH

The 10-fold amount of a 10% solution, which was previously stored for 2 months at room temperature, was used analogously to Example 1 instead of pure CDH.
All results are in the range of Example 1, ie a 10% solution of CDH was sufficiently storage stable to settlements and scored at the appropriate use concentration in the textile application, the same effect.

Example 8: Sensitization and skin irritation

An untreated raw ash PA 6.6 was cleaned in acetone, then thoroughly rinsed with water and dried. Thereafter, 3.75 g / L of CDH were padded at 100% liquor pickup and dried at 120 ° C. It was then gemoldet at 200 ° C for 30 s. The product was tested for sensitization to OECD 406 and skin irritation according to OECD 404.

The result was "non-sensitizing" and the Primary Skin Irritation Index (PSI) was 0, not irritating to the skin.

Claims (20)

1. A polyamide-containing material having a surface finish containing carbodihydrazide.
2. The material according to claim 1, characterized in that said polyamide-containing material is dyed, undyed or optically brightened.
3. The material according to either of claims 1 or 2, characterized in that said polyamide-containing material contains natural polyamides, especially wool and/or silk.
4. The material according to either of claims 1 or 2, characterized in that said polyamide-containing material contains synthetic polyamides.
5. The material according to any of claims 1 to 4, characterized in that said polyamide-containing material contains further polymers, especially polyesters, polysaccharides, polyurethanes and/or polyolefins.
6. The material according to any of claims 1 to 5, characterized by being in the form of fibers, non-wovens, knitted fabrics, woven fabrics or knitwear.
7. A process for finishing surfaces of polyamide-containing materials, characterized in that the carbodihydrazide, dissolved or dispersed in a liquid, is contacted with the surface, followed by removing the liquid.
8. The process according to claim 7, characterized in that the carbodihydrazide solution or dispersion is applied to the surface by exhaust processes, or especially by padding processes.
9. The process according to either of claims 7 or 8, characterized in that the carbodihydrazide is applied before or after, especially after, the dyeing and/or optical brightening.
10. The process according to any of claims 7 to 9, characterized in that a polyamide-containing material containing natural polyamides, especially wool and/or silk, is employed.
11. The process according to any of claims 7 to 9, characterized in that a polyamide-containing material containing synthetic polyamides is employed.
12. The process according to any of claims 7 to 11, characterized in that a polyamide-containing material containing further polymers, especially polyesters, polysaccharides, polyurethanes and/or polyolefins, is employed.
13. The process according to any of claims 7 to 12, characterized in that fibers, non-wovens, knitted fabrics, woven fabrics or knitwear is employed as said polyamide-containing material.
14. The process according to any of claims 7 to 13, characterized in that water is employed as a solvent or dispersant for the carbodihydrazide.
15. The process according to any of claims 7 to 14, characterized in that a liquor containing an amount of from 0.1 g/l to 20 g/l, especially from 0.5 to 10 g/l, carbodihydrazide is employed.
16. The process according to any of claims 7 to 15, characterized in that a liquor containing usual processing or effect chemicals, especially wetting agents, plasticizers, oleophobizing and/or hydrophobizing additives or thickeners, is employed.
17. The process according to any of claims 7 to 16, characterized in that the fabric is heat-set or preshaped after the treatment with carbodihydrazide.
18. Use of carbodihydrazide, or of a solution or dispersion containing it, as a textile auxiliary agent for the surface finishing of polyamide-containing materials.
19. The use according to claim 18 for stabilizing textiles against thermal influences and/or oxidants.
20. The use according to claim 19 for stabilizing textiles against nitrogen oxides, ozone or chlorine-containing oxidants.