GB2041420A

GB2041420A - Improvements in resin treatment methods for cloths containing cellulose fibres

Info

Publication number: GB2041420A
Application number: GB8003380A
Authority: GB
Original assignee: Sando Iron Works Co Ltd
Current assignee: Sando Iron Works Co Ltd
Priority date: 1979-01-31
Filing date: 1980-01-31
Publication date: 1980-09-10
Also published as: JPS55103368A; CA1140307A; DE3003194A1

Abstract

An aqueous resin solution is applied to a cellulosic cloth, and the resin is then condensed by hygrothermic treatment carried out at between 110 DEG -160 DEG C in an atmosphere of at least 85% humidity so as to fix the resin in the cloth.

Description

SPECIFICATION Improvements in resin treatment methods for cloths containing cellulose fibres This invention relates to improvements in resin treatment methods for cloths containing cellulose fibres.

It is well appreciated in the textile industry that the properties of cloths containing cellulose fibres may be improved by fixing a resin in the cloth. This applies equally to cloths made entirely from textile materials essentially comprising cellulose fibre, such as cotton or rayon, or to cloths in which the cellulose fibre is present together with some other textile material, as in union cloth or in blended yarn, woven or knitted cloths obtained from cellulose fibres and polyester fibres.

In a conventional method for fixing a resin in a cloth, a suitable amount of a thermo-setting aqueous resin solution is applied to the cloth, and a preliminary drying step is then carried out.

After preliminary drying, the resin is condensed in a heat treatment step performed with dry heat to form a highly crosslinked solid resin fixed in the cloth.

It is believed that in this conventional process the resin solution penetrates into the micelle gaps or amorphous parts of the cellulose fibres, together with water. Then, as the preliminary drying is carried out, the water content evaporates-this happening before the resin which has penetrated into the micelle gaps or the amorphous parts is condensed in the heat treatment step. Accordingly, it is thought that the fibre cells which have been expanded by the absorbed water are reduced back into their original state, so that the resin is condensed under dehydrated conditons. As a result, the cloth in which the resin has been fixed tends to become limp and lose its softness. Furthermore, the abrasion resistance and tearing strength of the cloth are inevitably lowered, and its cellulose content becomes brittle and yellowed.

The present invention seeks to overcome the problems associated with the conventional method by omitting the preliminary drying step and condensing the resin by hygro-thermic treatment, rather than by using dry heat.

Accordingly, this invention provides a method of fixing a resin in a cloth containing cellulose fibres, in which method an aqueous solution of a resin is applied to the cloth and the resin is thereafter condensed by hygro-thermic treatment to form a solid resin fixed in the cloth, the hygro-thermic treatment being carried out in an atmosphere of at least 85% humidity at a temperature of from 1 0 C to 1 60 C.

The aqueous resin solution employed in the method of the invention may be chosen from those employed in the dry-heat prior art methods. It will be appreciated that the dissolved resin is itself a polymeric condensation product, but one that is not condensed (and thus cross-linked) to such an extent that it is no longer soluble in aqueous media. Further condensation of the resin to form a highly cross-linked solid fixed in the cloth occurs only during the hygro-thermic treatment.

Aqueous resin solutions based primarily on melamine or urea resins may advantageously be employed.

The hygro-thermic treatment is conveniently carried out in a high pressure steamer, and preferably at a temperature of from 1 20 C to 1 40 C, still more preferably from 1 30 C to 1 40 C. In general, from 1 to 2 minutes of the treatment are required to condense the resin and satisfactorily fix it in the cloth; indeed, it has been found that fixing efficiencies (i.e. the amount of resin fixed in the cloth expressed as a percentage of the amount of resin applied to the cloth) obtained with the method of the invention closely approach those attainable using dry-heat prior art methods.

The major difference between the method of the invention and the dry-heat prior art methods is that in the method of the invention the condensation of the resin proceeds under damp conditions, and that difference is believed to account for the ability of the method of the invention to produce a product which retains its softness without becoming unduly limp.

Other advantages which have been obtained with the method of the invention are that the loss in strength of cellulose fibres occurring in the dry-heat prior art methods does not take place; the abrasion resistance of the treated cloth is improved by about 20 to 30% compared with the prior art methods; the whiteness of the cloth is not impaired by yellowing; and there is no discolouration in cases where a dyed cloth is treated.

The invention will now be further described in the following Example, which however is given by way of illustration only.

Example A sheet of a broad cloth of 110 g/m2, comprising 65% polyester and 35% cotton, was scoured and bleached according to conventional processes, and then the polyester was subjected to a 17% alkali weight reducing process carried out using a high pressure steamer.

The cloth was immersed in an aqueous solution of a resin (a product of MIKI TRI KEN KOGYO K.K.) comprising: 10% by weight of RIKEN RESIN MA-31 (a modified melamine resin having 80% effective component); 5% by weight of TRI KEN Sol (vinyl acetate having 45% solid component); and 3% by weight of TRI KEN Fixer (catalyst).

The cloth thus impregnated with the aqueous resin solution was passed through a mangle and wrung to a degree of 70%. Immediately afterwards, the cloth was either subjected without preliminary drying to a hygro-thermic treatment, or subjected to preliminary drying followed by a dry-heat treatment in accordance with the prior art, so as to condense the resin and fix it in the cloth.

In either case; the cloth was subsequently subjected to a soaping process carried out with an aqueous solution containing 0.3% of Monogen and 0.2% of soda ash (arranged to be in a bath ratio 1:30) for 10 minutes at 80"C. Finally, the cloth was washed with water and dried.

In a series of tests several portions of cloth were treated as described above, the conditions under which the condensation of the resin was carried out being as follows: Test 1: Preliminary drying was carried out at 1 00 C, followed by dry-heat baking for 3 minutes.

Test 2: No preliminary drying. Hygro-thermic treatment with steam in a saturated atmosphere was carried out at 1 1 0 C for 2 minutes.

Test 3: No preliminary drying. Steaming with saturated steam at 120"C for 2 minutes.

Test 4: No preliminary drying. Steaming with saturated steam at 1 30 C for 2 minutes.

Test 5: No preliminary drying. Steaming with saturated steam at 140"C for 2 minutes.

Test 6: No preliminary drying. Steaming with saturated steam at 1 50 C for 2 minutes.

It will be appreciated that Test 1 relates to a dry-heat prior art method, and that Tests 1-6 relate to methods of the invention.

After treatment the portions of cloth were compared against each other and an untreated portion of cloth in respect of fixing efficiency, bending resistance and discolouration. The results are set out below.

Fixing Bending Efficiency Resistance Discolouration Non-treated cloth - 103 mm Test 1 96% 70 Yellowed Test 2 30 94 None Test 3 67 88 None Test 4 94 82 None Test 5 96 81 None Test 6 93 82 None Note: Bending resistance was measured by the heart loop method.

The results show that greatest fixing efficiency is obtained in the method of the invention when operating within a preferred temperature range of from 1 30 C to 1 40 C, as indicated by the results of Tests 4 and 5. As for bending resistance, the value obtained in Test 1 is 70 mm while the values obtained in Tests 4 and 5 are 81 and 82 mm. This shows that cloth treated in accordance with the invention is less limp than that treated by the prior art method, and accordingly has a greater tearing strength.

Further tests were conducted by varying the length of time for which the hygro-thermic steaming process was carried out. Details of these tests and the results obtained from them are shown below: Test 7 : No preliminary drying. Hygro-thermic treatment with steam in a saturated atmosphere was carried out at 140 C for 0.5 minutes.

Test 8 : No preliminary drying. Steaming with saturated steam at 140"C for 1 minute.

Test 9 . No preliminary drying. Steaming with saturated steam at 1 40 C for 2 minutes.

Test 10: No preliminary drying. Steaming with saturated steam at 140 C for 3 minutes.

Test 11: No preliminary drying. Steaming with saturated steam at 1 40 C for 5 minutes.

Fixing Bending Efficiency Resistance Discolouration Test 7 65% 88 mm None Test 8 97 80 None Test 9 96 81 None Test 10 85 85 None Test 11 80 80 None The results of tests 7 to 11 show that the best resin fixing efficiency at 1 40 C occurs when the hygro-thermic treatment is carried out for between 1 and 2 minutes, as in Tests 8 and 9.

The fixing efficiency decreases if the treatment time much exceeds 2 minutes, probably because the combined action of steam distillation and hydrolysis reduces the amount of resin in the cloth.

Claims

CLAiMS

1. A method of fixing a resin in a cloth containing cellulose fibres, in which method an aqueous solution of a resin is applied to the cloth and the resin is thereafter condensed by hygro-thermic treatment to form a solid resin fixed in the cloth, the hygro-thermic treatment being carried out in an atmosphere of at least 85% humidity at a temperature of from 1 0 C to 160"C.

2. A method as claimed in Claim 1, in which the aqueous resin solution contains melamine resin or urea resin.

3. A method as claimed in Claim 1 or Claim 2, in which the hygro-thermic treatment is carried out in a high pressure steamer.

4. A method as claimed in any of Claims 1 to 3, in which the hygro-thermic treatment is carried out at a temperature of from 1 20 C to 1 40 C.

5. A method as claimed in Claim 4 in which the temperature is from 1 30 C ro 1 40 C.

6. A method as claimed in any of Claims 1 to 5, in which the hygro-thermic treatment is carried out for from 1 to 2 minutes.

7. A method as claimed in any of Claims 1 to 6, in which the hygro-thermic treatment is carried out in a atmosphere substantially saturated with steam.

8. A method as claimed in Claim 1 and substantially as hereinbefore described with reference to any one of Tests 2 to 11.

9. A cloth whenever treated by the method of any one of Claims 1 to 8.