EP3728726A1

EP3728726A1 - Method for dyeing the surface of a workpiece

Info

Publication number: EP3728726A1
Application number: EP18829187.6A
Authority: EP
Inventors: Thomas Bechtold; Tung Pham; Amalid Mahmud-Ali; Markus Krüger; Günter GRABHER
Original assignee: Grabher Guenter Textilveredelungs GmbH; Universitaet Innsbruck; Schoeller GmbH and Co KG Austria; Schoeller GmbH and Co KG Deutschland
Current assignee: Grabher Guenter Textilveredelungs GmbH; Universitaet Innsbruck; Schoeller GmbH and Co KG Austria; Schoeller GmbH and Co KG Deutschland
Priority date: 2017-12-19
Filing date: 2018-12-19
Publication date: 2020-10-28
Also published as: WO2019119008A1; AT520785A2

Abstract

The invention relates to a method for dyeing the surface of a workpiece with a dye, wherein the polypropylene workpiece is impregnated in a first step with a cationic polypropylene dispersion and is dyed in a subsequent second step with an anionic dye.

Description

METHOD FOR STAINING THE SURFACE OF A WORKPIECE

The invention relates to a process for dyeing the surface of a polypropylene workpiece with a colorant. Moreover, the invention relates to a product comprising a colored polypropylene workpiece.

BACKGROUND OF THE INVENTION

Polypropylene workpieces are e.g. as polypropylene fibers in textile fabrics widely used. A particular characteristic of polypropylene fibers results from their construction as a hydrocarbon-based fiber, which has very hydrophobic properties. The low capacity of polypropylene fibers for moisture absorption from the air or as capillary water, make these fibers particularly interesting for applications in which rapid drying and a reduced wetness are required. Typical applications are therefore sports underwear or skin-near layers in disposable diapers. However, polypropylene fibers are also used e.g. used in the automotive industry (e.g., as carpets).

Especially in textile applications there is a need for colored polypropylene fibers, which results on the one hand from functional and on the other hand optical and fashionable reasons. Therefore, dyeing methods for polypropylene (PP) are of great interest. Although the hydrophobic character of PP substantiates the particular functional properties, it makes the adhesion of dyes in aqueous dyeing processes very difficult due to the lack of functional groups. Dyeing with other systems is also very difficult with polypropylene fibers because the dyes do not adhere to the PP.

The most commonly used dyeing method relies on the incorporation of dye at the level of fiber production. In this case, a dye-containing master batch is mixed with the polypropylene during the melt spinning process for the production of the fibers, resulting in the extrusion process colored fibers. According to this method of mass coloration of PP, any colors with very high fastness requirements can be produced. However, since the dyed fibers are formed in the fiber spinning process, there are several critical drawbacks: the method is economical only at relatively high production rates because the entire spin line must be filled with colored polymer and high levels of transitional colors between two shades are incurred as waste. The dyeing takes place at the level of the fibers and is therefore not changeable in later processes, just as no yarns or areas can be dyed or printed, which limits the technical flexibility very much. To make dyeable polypropylene-based fibers already prepared, various concepts have been proposed in the literature. Several staining techniques attempt to improve the adhesion of colorants to textiles with polypropylene fibers by incorporating polymers with functional groups into the spin mass. However, these "incorporation techniques" have the disadvantage that a simultaneous change in the fiber properties occurs, whereby the textile approaches other fiber polymers and thus lost the special properties of the polypropylene fiber. Other techniques attempt to combine the colorant and polypropylene fibers by reaction, which is laborious and requires questionable chemicals.

BRIEF DESCRIPTION OF THE INVENTION

In summary, it can be stated that various methods for coloring polypropylene are available in the prior art. Each of these methods, however, has specific disadvantages, so today only a few methods are actually used.

It is an object of the present invention to provide a process for dyeing polypropylene workpieces which is feasible on existing textile processing equipment with existing textile dyes of useful color depths and useful color fastness. Also correspondingly colored workpieces should be provided.

This object is achieved by a method for dyeing the surface of a workpiece with a colorant, characterized in that the workpiece is impregnated in a first step with a cationic polypropylene dispersion and dyed in a subsequent second step with an anionic colorant.

In addition, the object is achieved by a product comprising a workpiece having on the surface a layer comprising polypropylene and at least one cationic surfactant, wherein on the layer an anionic colorant is arranged.

Polypropylene dispersions have been known for some time. This is a substantially aqueous system in which polypropylene is dispersed. In certain cases, an emulsion may also be present. In this case polypropylene with short chain lengths and low isotacticity is used. A cationic polypropylene dispersion is understood to mean one which has a cationic surfactant. The cationic surfactant attaches to the dispersed polypropylene.

It is therefore preferred that the polypropylene dispersion is a dispersion of polypropylene with a cationic surfactant.

The impregnation with the cationic polypropylene dispersion is carried out in the simplest case by immersing the workpiece in a bath in which the cationic polypropylene dispersion is present. As a result, a layer of polypropylene with cationic surfactant forms on the surface of the workpiece. This layer is adsorbed on the surface and the cationic surfactant gives it on the surface the character of a positive charge.

The workpiece is preferably one which has plastic. Particularly preferably, it is a workpiece which comprises polypropylene.

Furthermore, it can be provided that the workpiece is dried after impregnation with the cationic polypropylene dispersion. In the simplest case, this is done by removing the workpiece from the bath in which the cationic polypropylene dispersion is located and drying in air. By increasing the temperature drying can be accelerated.

Although it has been found that the impregnation of the workpiece with the cationic polypropylene dispersion already leads to a layer that permanently adheres to the surface (adsorbed), it has nevertheless proved to be advantageous if the workpiece after impregnation with the cationic polypropylene dispersion on 100 ° C, preferably to between 110 and 155 ° C, is heated. As a result, the layer of polypropylene with cationic surfactant on the surface of the workpiece easily melts and melts on the workpiece. However, it is not a complete melting of the layer but a process in which - similar to the sintering - only slightly softens the surface.

Melting the layer of polypropylene with cationic surfactant on the surface of the workpiece significantly increases the durability of the color and also allows the product to be cleaned in the cooking cycle. The anionic colorant may be any anionic colorant used in the dyeing industry. They are preferably anionic dyes. Particularly preferred are anionic dyes which are normally used in wool dyeing, for example anionic natural dyes. Anionic dyes are sometimes referred to as acid dyes.

The steps of drying and heating can be combined and done simultaneously in one step.

The method is preferably used in the textile industry, so that the workpiece preferably comprises polypropylene fibers.

The polypropylene workpiece can be flat. It preferably comprises polypropylene fibers. It can be e.g. to trade a fabric, knits, fleece, etc. Analogously, films, plates, irregularly structured workpieces and thick workpieces can be modified.

With regard to the product, it may be provided that the layer is partially or completely melted onto the surface of the polypropylene workpiece.

As set forth below, the invention also relates to a process for dyeing the surface of a workpiece with a colorant, which is characterized in that the workpiece is impregnated in a first step with an anionic polypropylene dispersion and dyed in a subsequent second step with a cationic colorant becomes.

The details set out above apply to a cationic and an anionic colorant with altered signs also for the variant anionic polypropylene dispersion and cationic colorant.

Therefore, the invention also relates to a product comprising a workpiece having on the surface a layer comprising polypropylene and at least one anionic surfactant, wherein on the layer a cationic colorant is arranged.

In all embodiments, it is preferably provided that the workpiece comprises a plastic, preferably polypropylene, particularly preferably comprises polypropylene fibers. Furthermore, the workpiece can be formed flat, in particular comprise at least one woven fabric, a knitted fabric, a nonwoven fabric, a layer, a plate, an irregularly constructed workpiece or a combination thereof.

It is preferably provided that the layer is melted onto the surface of the workpiece.

The invention also relates to a product comprising a workpiece which has on the surface a layer which comprises polypropylene and at least one cationic surfactant, wherein an anionic active substance is arranged on the layer.

The invention also relates to a product comprising a workpiece which has on the surface a layer comprising polypropylene and at least one anionic surfactant, wherein a cationic active substance is arranged on the layer.

DETAILED DESCRIPTION OF THE INVENTION

The inventors have found that by impregnating polypropylene workpieces (e.g., polypropylene fibers or polypropylene fiber textile fabrics) with a cationic polypropylene dispersion, the surface charge of the fibers can be increased to such an extent that staining with anionically charged dyes, e.g. for wool or polyamide is possible.

In one embodiment of the invention, a polypropylene fiber is impregnated with a cationic polypropylene dispersion from the aqueous phase. If a polypropylene dispersion with 40% solids content is used, it can be applied undiluted or preferably diluted with water to the fiber material by immersion and squeezing. The amount of deposited on the fabric polypropylene dispersion moves at a liquor pick-up of 80%, between 32% and 3% of the weight of the goods. In a preferred embodiment, between 20% and 10% of polypropylene dispersion is applied, and more preferably between 25% and 15% of the product mass is applied to polypropylene dispersion.

After the orders, the aqueous phase is dried, the temperature being carried out in customary drying apparatuses, for example clamping frames, drum dryers, pressure dryers corresponding to the form of formation of the fibers, and the drying temperature preferably between 80 ° C. and 130 ° C., more preferably between 105 and 15 ° C. lies. The drying energy can be transmitted by hot air, superheated steam, contact heat, infrared radiation or microwave radiation, although other drying methods can be used.

After the drying, the applied polypropylene dispersion is fixed by a thermal step on the goods. The required temperature of the fixation depends on the molecular weight of the polypropylene dispersion used and is usually between 1 10 ° C and 160 ° C, preferably between 115 and 155 ° C, more preferably between 120 ° C and 140 ° C. The required lower limit of the temperature is determined by the fixation of the PP dispersion and the upper limit is determined by the maximum treatment temperature of the PP fiber. If the lower limit is not reached, adsorption takes place, but the fixation of the dispersion is not ideal for certain textile applications in which frequent cleanings (especially at high temperatures) occur. If the upper temperature limit is exceeded, a thermal change of the fiber structure of the PP fiber begins, which would result in the loss of the molecular orientation and thus the specific fiber properties.

Such a surface treated with a cationic polypropylene dispersion fiber can now be dyed with conventional acid dyes. Similar to wool and silk, the fiber now has sufficient cationic charges on the surface, which allow the anionic acid dye to bind.

Thus, a thus treated PP fiber can also be advantageously used in admixture with other fibers, e.g. Wool, dye polyamide one bath. In an analogous manner, other fibers may be admixed and these may be dyed by the appropriate methods, for example, a PP / polyester fiber blend may be dyed by the same procedures as a wool / polyester fiber blend.

By using existing dye groups, a wide range of color shades can be achieved and conventional dyeing plants can be used for the processes. If the basis of this invention is known, other variants of the application technique can be used, e.g. Pad-Dry-Thermosol techniques.

If the cationic polypropylene dispersion is applied locally by an application technique, eg by printing, spraying, etc., pattern or local staining can also be achieved in a subsequent process or in the printing process. Instead of the negatively charged dyes, it is also possible to link functional substances, for example antimicrobial agents, optical brighteners, at the existing cationic centers in an analogous manner.

To the knowledge of the subject invention, an analogous procedure by using anionic polypropylene dispersion is possible, in which case the modified fibers carry a negative charge and the dyeing is carried out with cationic dyes. By adaptation and expert optimization, the technique can be adapted to other fibers, in particular the hard-to-dye fibers of UHMPE (Ultra high molecular weight polyethylene) or aromatic polyamides (eg Kevlar, Nomex), aromatic polyesters (eg Vextran) or also to call glass fibers. The thermal treatment conditions must be adapted to the resistances and properties of the fibers, e.g. by using low-melting polypropylene dispersions or by using polyethylene dispersions.

APPLICATIONS:

Application example 1

A knit fabric made from PP fibers is impregnated with a cationic PP dispersion (eg Michern emulsion, 28640 40% PP volume fraction) by an impregnation process. The different concentrations of PP dispersion listed in Table 1 are applied and fixed after drying at 100 ° C at elevated temperature between 110 and 155 ° C. The liquor pickup when applying the dispersion is about 100%. For comparison, PP samples are subjected to the same thermal treatment. This is followed by dyeing with an anionic dye (acid dye Nylosan Red F-2R) with a color depth of 1% (dye 10 mg / g of fabric) at 60 ° C (1 h), after dyeing is twice at 60 ° C for 10 rinsed min once and again for 10 min with cold water. Dye uptake can be assessed by the CIELab coordinates and the K / S value at 480 nm. The stability of the coloration is assessed by wet fastness (DIN 54006, grade 5 very good, grade 1 very poor). Table 1. Impregnation of PP knitted fabrics with cationic PP dispersion (duplicate determinations). Conditions, color coordinates and fastnesses

Sample content of fixative K / S Authenticity Authenticity

Dispersion temp.

% Colorant ANBL. Wool

1a 100 110 49.49 43.25 21.82 5.97 3.5 3-3.5

1 b 100 110 48.72 45.30 24.28 6.73 3.5-4 3.5

2a 100 130 47.56 46.87 25.10 8.26 3.5-4 4

2b 100 130 48.29 46.44 23.95 7.18 3.5-4 4

3a 100 155 47.33 43.56 22.13 7.08 4 4-4.5

3b 100 155 49.23 44.16 20.11 6.33 4 4-4.5

4a - 110 71.00 14.23 4.65 0.70 4-4.5 4.5-5

4b - 110 71.99 12.39 5.82 0.69 4-4.5 4.5-5

5a - 130 68.93 16.07 7.19 0.92 4-4.5 3.5

5b - 130 68.77 13.40 7.02 0.88 4-4.5 3.5

6a - 155 70.63 14.30 5.98 0.75 4-4.5 4-4.5

6b - 155 66.95 17.82 12.15 1.21 4-4.5 4-4.5

The values of the color coordinates clearly show the higher dye uptake and color depth that could be achieved by the treatment. The fastness remains at a good level, the higher color depth results in a reduction in the authenticity.

Application Example 2

Yarn samples of Vectran (aromatic polyester, Nm36 / 2) and UHMPE (ultra high molecular weight polyethylene, Nm 54/2) are treated and dyed in an analogous manner to application example 1.

The dispersion of cationic polypropylene is diluted with water (60% dispersion and 40% water). The fixing temperature used is 130 ° C. for 10 minutes. The dyeing with acid dye is carried out analogously to application example 1. Table 2. Impregnation of knitted fabrics with cationic PP dispersion

(Double determinations). Conditions, color coordinates and fastnesses

Sample Material Content of L * a * b * K / S Authenticity Authenticity

Disp.

Farbänd. ANBL.

% Wool

^~ 7e Vectran 6Ö 52.28 43.97 30.19 5781 4-4,5 2 5

7b Vectran 60 53.15 44.20 29.55 5.54 4-4.5 3

8a UHMPE 60 54.35 51.76 37.55 6.96 3.5-4 3.5

8b UHMPE 60 56.34 47.50 32.62 5.07 4 3.5

9a Vectran - 72.51 11.43 14.67 0.62 -

9b Vectran - 74.07 10.70 14.82 0.55 -

10a UHMPE - 77.70 20.32 17.20 0.58 -

10b UHMPE - 79.56 19.95 16.91 0.50 -

The fastness of the untreated samples was not determined, since a low color absorption was observed and the authenticity was therefore of no further relevance.

Figures 1 and 2 shows laser scanning microscope photographs of treated (Figure 1) and untreated PP fibers (Figure 2). It can be clearly seen in the figures that deposits are formed by layer formation on the treated PP fibers.

The presence of surfactants is also recognizable by means of FT-IR.

Claims

1. A process for dyeing the surface of a workpiece with a colorant, characterized in that the workpiece is impregnated in a first step with a cationic polypropylene dispersion and dyed in a subsequent second step with an anionic colorant.

2. The method according to claim 1, characterized in that the polypropylene dispersion is an emulsion of polypropylene with a cationic surfactant.

3. The method according to claim 1 or claim 2, characterized in that the workpiece is dried after impregnation with the cationic polypropylene dispersion.

4. The method according to any one of claims 1 to 3, characterized in that the workpiece after impregnation with the cationic polypropylene dispersion to above 100 ° C, preferably to between 110 and 155 ° C, is heated.

5. The method according to any one of claims 1 to 4, characterized in that the workpiece comprises a plastic, preferably polypropylene, particularly preferably comprises polypropylene fibers.

6. A method for dyeing the surface of a workpiece with a colorant, characterized in that the workpiece is impregnated in a first step with an anionic polypropylene dispersion and dyed in a subsequent second step with a cationic colorant.

A product comprising a workpiece having on the surface a layer comprising polypropylene and at least one cationic surfactant, wherein an anionic colorant is disposed on the layer.

8. A product comprising a workpiece having on the surface a layer comprising polypropylene and at least one anionic surfactant, wherein a cationic colorant is disposed on the layer.

9. Product according to claim 7 or claim 8, characterized in that the workpiece comprises a plastic, preferably polypropylene, particularly preferably comprises polypropylene fibers.

10. Product according to claim 9, characterized in that the workpiece is formed flat, in particular at least one fabric, a knitted fabric, a nonwoven fabric, a layer, a plate, an irregularly constructed workpiece or a combination thereof.

11. Product according to one of claims 7 to 10, characterized in that the layer is fused to the surface of the workpiece.

12. A product comprising a workpiece having on the surface a layer comprising polypropylene and at least one cationic surfactant, wherein an anionic active agent is disposed on the layer.

13. A product comprising a workpiece having on the surface a layer comprising polypropylene and at least one anionic surfactant, wherein on the layer a cationic active ingredient is disposed.