CN1077184C - Fabric treatment - Google Patents

Abstract

The degree of fibrillation and/or the tendency to fibrillation of lyocell fabric can be reduced by treating the fabric with a low-formaldehyde or zero-formaldehyde crosslinking resin, heating the treated fabric to cure the resin, and washing and drying the fabric. The treatment can be applied to dyed fabric.

Description

fabric treatment

Background of the invention

1. Field of invention

The present invention relates to a method of reducing the degree of fibrillation and the tendency to fibrillate of fabrics made from lyocell fibers.

2. Description of related technologies

It is known to produce cellulose fibers by extruding a solution of cellulose in a suitable solvent into a coagulation bath. This extrusion solidification method is called "solvent spinning", and the cellulose fiber produced by this method is called solvent spinning cellulose fiber. An example of this method is described in US Patent A-4,246,221, the contents of which are incorporated herein by reference. The cellulose is dissolved in a solvent such as a tertiary amine N-oxide (eg N-methylmorpholine N-oxide). The resulting solution is extruded through a suitable spinnerette to form filaments which are then coagulated, washed with water to remove the solvent and dried. At some stage after solidification, these filaments are usually chopped to form staple fibers. It is also known that cellulose fibers can be produced by extruding a solution of cellulose derivatives into a regeneration coagulation bath. An example of such a process is the viscose process in which cellulose xanthate is used as the cellulose fiber. Both types of methods are wet spinning methods. Solvent spinning has several advantages over other known methods of producing cellulose fibers such as viscose, such as its lower environmental emissions.

The lyocell fiber mentioned here refers to the cellulose fiber obtained by the organic solution spinning method, wherein the organic solvent used is basically a mixture of organic compounds and water, and the cellulose involved in the method is lyo-spun Neither of the steps of dissolving and spinning produced cellulose derivatives. The "lyocell fiber" and "Lyocell fiber" mentioned here are synonymous. The lyocell fabric mentioned here refers to a fabric woven or knitted with many yarns, at least some of which contain lyocell fibers, all of which are fibers of this type or a mixture with other types of fibers.

Fibers have a tendency to fibrillate, especially when subjected to mechanical stress in a wet state. Fibrillation occurs when the fiber structure is disrupted longitudinally so that fine fibrils are partially detached from the fibers, giving the fibers and fabrics containing such fibers (such as woven or knitted fabrics) a hairy appearance . Fabrics containing fibrillated fibers will have a "matte" appearance after dyeing which is not suitable for aesthetics. This fibrillation is believed to result from mechanical abrasion of the fibers during handling in the wet swollen state. Fibers are inevitably subjected to mechanical abrasion during wet processing such as scouring, bleaching, dyeing and washing. If the treatment temperature is high and the time is long, a greater degree of fibrillation will occur. Lyocell fabrics seem to be particularly sensitive to this abrasion and are therefore found to be more prone to fibrillation than fabrics of other types of cellulose fibers. Cotton fabrics, on the other hand, have a very low fibrillation tendency by nature.

European Patent-A-538,977 teaches that fibrils can be removed from fibrillated woven lyocell fabrics by treatment with a solution of cellulase enzymes. Cellulase is an enzyme substance that accelerates the hydrolysis of cellulose. However, this treatment is not as effective as desired, and the disposal of the used enzyme solution also poses environmental problems.

For many years, it has been known that cellulose fabrics can be treated with crosslinking agents to increase their wrinkle resistance, for example, in Encyclopaedia of Chemical Technology edited by Kirk-Othmer, 3rd ed., Volume 22 (1983), Wiley-Interscience entitled In the section "Fabrics (finishing)" (p769-790), and in the article H. Petersen, Rev. Prog. Coloraton, Vol 17 (1987), p7-22. The cross-linking agent sometimes uses other names, such as cross-linking resin, chemical finishing agent, resin finishing agent, etc. Cross-linking agents are small molecular substances containing many functional groups that can form cross-bonds with hydroxyl groups in cellulose. In conventional finishing, cellulosic fabrics are first treated with a crosslinking agent, eg applied through a pad bath, dried, and heated to cure the resin and cause crosslinking (the pad-bake-bake process). These anti-wrinkle finishes are known to embrittle cellulosic fabrics, resulting in reduced abrasion resistance, tensile strength, and tear strength.

The first crosslinking systems were based on resins such as formaldehyde, urea-formaldehyde and melamine-formaldehyde. They have many problems. These treatments cause temporary hardening of the fabric due to the presence of external binding resins. The treated fabric tends to give off an unpleasant odor when stored. These odorous substances include the amine catalysts used to harden the resin and the poisonous formaldehyde. It is therefore considered necessary to laundere treat fabrics to remove externally bonded resins and by-products of resin formation which cause malodor. However, this washing and subsequent drying increases production costs.

These above-mentioned systems have mostly been replaced by systems containing so-called "low-formaldehyde resins" and "zero-formaldehyde resins" as crosslinking agents. There is a known class of such crosslinking agents, N-methylol-containing resins, which are small molecular substances containing two or more N-methylol or N-alkoxy groups (especially N-methoxy groups) . N-methylol resins are usually used in conjunction with selected acid catalysts to improve crosslinking properties. In a typical method, a solution containing about 5-9 (weight) % N-methylol resin cross-linking agent and 0.4-3.5 (weight) % acid catalyst is padded onto a cellulose fabric to achieve The liquid absorption rate is 60-100 (weight)%. Then, the wetted fabric is dried and heated to harden and fix the crosslinking agent. Fabrics treated with low- or zero-formaldehyde resins generally do not temporarily harden and do not emit unpleasant odors. Stiffened jersey and finished garments are rarely laundered prior to sale to consumers.

Summary of the invention

One content of the present invention is the method for reducing the fibrillation tendency of lyocell fabric, and its steps are:

a) treating the fabric with a low or zero formaldehyde crosslinking resin;

b) heating the fabric under appropriate conditions to make the resin and cellulose react;

c) washing the fabric;

d) Dry the fabric.

In this aspect of the invention, as well as others described below, the fabric is treated with a crosslinker resin and heated to cause a reaction between the resin and the cellulose in the form of a wide knitted fabric. In a possibly preferred embodiment of this and other aspects of the invention, the fabric is washed and dried in flat knit form, thus suitable for cutting into panels for garment or other textile manufacture. In yet another embodiment of this and other aspects of the invention, the fabric is first formed into a garment or other textile and then washed and dried to complete the process of the invention.

The second content of the present invention is a kind of method that reduces the degree of fibrillation of lyocell fabric, and it comprises the following steps:

a) treating the fabric with a low or zero formaldehyde crosslinking resin;

b) heating the fabric under appropriate conditions to make the resin and cellulose react;

c) washing the fabric;

d) Dry the fabric.

The third content of the present invention is a method for providing a low degree of fibrillation and a low fibrillation tendency of lyocell fabric, which comprises the following steps:

a) scouring and dyeing of fabrics, thereby causing fibrillation in the fabrics;

b) treating the fabric with a low or zero formaldehyde crosslinking resin;

c) heating the fabric under appropriate conditions to make the resin and cellulose react;

d) washing the fabric;

e) Dry the fabric.

In this third aspect of the invention, the fabric may be bleached between scouring and dyeing in step (a), and a drying step may also be inserted between steps (a) and (b). After step (c), the fabric may exhibit such a high degree of fibrillation that textiles made therefrom would also be commercially unacceptable. After step (e), it may be commercially desirable to fabric in open-width knit or woven form with a low degree of fibrillation.

A preferred class of crosslinking resins are the N-methylol resins. Examples of preferred methylol groups can be found in the above-mentioned Encyclopedia edited by Kirk-Othmer and in the article by Petesen. For example: 1,3-dimethylolethylene urea (DMEU), 1,3-dimethylol propylene urea (DMPU) and 4,5-dihydroxy-1,3-dimethylol Ethylene urea (DHDMEU). Other examples include oolong, triazone, carbamate based compounds. Another class of preferred crosslinking agents are compounds based on 1,3-dialkyl-4,5-dihydroxy(alkoxy)ethyleneureas and derivatives thereof. Yet another example of a suitable crosslinking agent is melamine, yet another example is butanetetracarboxylic acid (BTCA). A variety of crosslinking resins can also be used.

Crosslinking agents for crease-resistant finishing of cellulosic fabrics are usually used in combination with a catalyst. The catalyst acts to accelerate the crosslinking reaction and harden and fix the resin. The process of the present invention advantageously employs catalysts that perform this function when using the selected crosslinking agent. For example, N-methylol resins are preferably used in combination with an acid catalyst such as an organic acid such as acetic acid or an inorganic acid such as zinc nitrate or magnesium chloride. Latent acids such as ammonium, amine and metal salts can also be used. Mixed catalyst systems may also be used.

The crosslinking agent and any catalyst are preferably applied to the fabric from a solution, preferably an aqueous solution. The solution can be applied to the fabric by known methods, for example, the solution can be applied to the fabric by padding, or the fabric can be passed through a treatment bath of the solution. Fabrics may be woven or knitted. The solution should contain at least about 2% by weight of crosslinking agent, preferably 3-6% by weight. If a catalyst is used, its content can contain at least 1 (weight)%, preferably 1-2 (weight).

After the cross-linking resin treatment is carried out according to the method of the present invention, the fabric is heated to fix and harden the cross-linking agent. The fabric can also be dried. The heating step may be performed before, simultaneously with or after the drying step. The time and temperature required for heating will depend on the nature of the crosslinking agent and catalyst used. After heating and or optional drying, the fabric may contain at least about 0.5 wt%, preferably about 1.0 wt%, more preferably about 2.0 wt% of anchored crosslinking agent (based on cellulose weight) , but usually not more than 4 (weight)%. It is generally found that 70-90% of the crosslinking agent in the wet fabric will be fixed to the cellulose.

The concentration of the resin in the bath is selected according to the activity and hardening efficiency of the resin in order to obtain the desired amount of fixed resin on the fabric.

After heating and fixing, washing and drying are carried out as usual for cellulosic fabrics.

Crosslinking agents are generally believed to reduce the abrasion resistance of cellulosic fabrics, but the very low degree of fibrillation of fabrics treated in accordance with the present invention is particularly surprising. The method of the present invention requires a further wet processing step which, as previously mentioned, causes fibrillation of the lyocell fabric.

Fabrics treated according to the invention have excellent anti-fibrillation properties compared to untreated fabrics. Fabrics treated according to the invention are suitable for making textiles such as clothing. Such textiles can be starched and the tendency to fibrillation remains small or only increases slowly.

The method of the present invention is applicable to already dyed fabrics, including those dyed by methods such as rope dyeing which are known to cause mechanical abrasion. This is an advantage of the present invention because it is known that rope dyeing of fabrics generally improves bulk and relaxation of the fabric, resulting in a superior hand. The method of the present invention can be used for already fibrillated, even the fabric of severe fibrillation, it is surprisingly found that when the fabric with a very high degree of fibrillation is processed by the method of the present invention, its degree of fibrillation is generally very low. For most purposes, a fabric with a high degree of fibrillation is considered to be of substandard quality, and consequently its subsequent fabrication is not cost-effective. A particular advantage of the present invention is that it allows such poor quality fabrics to be transformed into first quality fabrics and textiles.

The degree of fibrillation of the material was measured using Test Method 1 described below. Test Method 1 (Fibrillation Measurement)

There is no accepted standard method for the measurement of fibrillation. The following method was used to obtain the fibrillation index (F.I.). Some fiber samples were arranged in order of increasing degree of fibrillation. For each fiber sample, measure a standard length. Then count the number of fibrils (fine burrs extending outward from the main fiber body) along this standard length, and then measure the length of each fibril. A value is obtained by multiplying the number of fibrils per fiber by the product of the average length of fibrils. The fiber with the highest value for this product was considered the most fibrillated fiber and was defined as a fibrillation index of 10. The fibrillation index of fibers completely free of fibrillation was assigned zero, while the rest of the fibers were evenly ranked between 0 and 10 according to the number measured microscopically.

With the fibers thus measured, a standard rating was established for the fibrillation index. If you want to measure the fibrillation index of any other fiber sample, compare its 5 or 10 fibers with the standard-grade fiber visually under a microscope, and average the visual values of each fiber to obtain the value of the tested sample. Fibrillation index. The visual comparison of the value and the average is many times faster than the actual measurement, and it is found that as long as the fiber technician is skilled, the measurement results are consistent.

Fibers can be extracted from the fabric surface for fibrillation index measurement. Woven and knitted fabrics with an F.I.% exceeding 2.0 to 2.5 have an unsightly appearance.

Description of the preferred embodiment

The present invention will be illustrated below with examples. In each case, the undried fibers used were prepared by extruding a solution of N-methylmorpholine N-oxide (NMMO) into a water bath and then water washing the resulting fibers to be substantially free of NMMO.

Example

A F.I. zero 100% lyocell spun woven fabric was desized, scoured and jet dyed. Desizing is carried out at 70°C for 45 minutes with an aqueous solution of 1.5 g/l commercial amylase preparation at pH 6.5-7.5. Scouring was carried out at 95°C for 60 minutes with an aqueous solution containing 2 g/l sodium carbonate and 2 g/l cationic detergent. Dyeing is done with a dye containing Procion Navy HE-R150 (Procion is a trademark of Zeneca plc) (the weight of the dye is 4% of the weight of the fabric), 80g/l sodium sulfate and 20g/l sodium carbonate. The aqueous solution was carried out at 85°C for 120 minutes. The fabric was subsequently rinsed with water at 70°C and then at room temperature; soaped off at 95°C for 20 minutes with an aqueous solution containing 2 g/l Sandopur SR (Sandopur is a trademark of Sandoz AG); dehydration; and finally dried. This step is a typical rope-like process for cellulosic fabrics. The fibers thus treated were highly fibrillated with an F.I. of 4.5.

Samples of the dyed fabrics were padded with aqueous solutions of the low-formaldehyde resin DHDMEU (available from Hoechst AG under the trade mark Arkofix NG conc) with varying contents. The solution contained the acid-releasing catalyst recommended by the resin supplier in an amount of 25% by weight of ArkofixNG conc. The fabric samples were then dried at 110°C and the resin was rapidly hardened for 30 seconds at 180°C. The fabric samples were reloaded into the jet dyeing machine and scoured twice as before. The sample was dehydrated again, and was wet cloth padding with a dispersion containing 50g/l polysiloxane softener (supplied by Redolf Chemi-cals Ltd, trademark Rucofin AO736), and then dried at 110°C. The results are listed in Table 1.

Table 1 Resin % W/W 0.0 1.0 2.0 4.0 6.0 8.0 Table in the bath is 0.0 0.5 1.0 2.0 3.0 4.0 fat % W/WF.I. 5.8 1.5 0.5 0.3 0.3

The amount of resin fixed on the fabric is estimated based on Arkofix NG having 70% active solids, 80% extrusion fluid, and 85% hardening efficiency.

It can be seen that the F.I. of the untreated fabric increases to 4.5 during further wet treatments like those described above, whereas conversely, the resin treatment actually reduces the F.I. of the fabric from 4.5 to a commercially acceptable value of 1.9 or even less .

Claims (10)

1. one kind provides original fiber degree and the method for being inclined to all low solvent spun fibre cellulose fabric, it is characterized in that the step that it comprises is:

A) fabric is carried out (1) boiling-off and (2) dyeing, thereby cause the fibrillation of fabric;

B) use the aqueous solution of the crosslinked resin that contains the low or zero formaldehyde of 3% to 6% (weight) to fabric

Handle;

C) fabric is heated being enough to cause under the condition that resin and cellulose react, with

The O.5%-4% crosslinked resin of (weight) of the plain weight of anchoring fiber on fabric;

D) with fabric washing;

E) with fabric drying.

2. the method for claim 1, it is characterized in that this a) (2) staining procedure carry out on fabric with the rope form form.

3. method as claimed in claim 1 or 2 is characterized in that this method after a) (1) boiling-off step, and a blanching step a) is arranged before (2) staining procedure.

4. method as claimed in claim 1 or 2 is characterized in that this method is after a) (2) staining procedure, at b) fabric is carried out also comprising a drying steps before crosslinked resin handles.

5. method as claimed in claim 1 or 2 is characterized in that d) washing and e) dry two steps all carry out on flat fabric.

6. method as claimed in claim 1 or 2 is characterized in that at c) after the heating steps, at d) before the washing step, fabric is made into clothes or other textiles.

7. as the described method of claim l, it is characterized in that this crosslinked resin contains at least a N-hydroxymethyl resin.

8. method as claimed in claim 7 is characterized in that this N-hydroxymethyl resin uses together with a kind of acid catalyst.

9. method as claimed in claim 1 or 2, it is characterized in that this crosslinked resin contains at least a oolong, triazinone, carbamate, the l of being selected from, 3-dialkyl group-4, the resin of 5-dihydroxy (alkoxyl) ethylidene-urea and derivative, melamine or ethylene-dimalonic acid.

L0. method as claimed in claim 1 or 2 is characterized in that through c) after the heating steps, fabric contains the crosslinking agent based on about at least 2 (weight) % set of cellulose.