EP1996760A1

EP1996760A1 - Whitener for polyester fabrics

Info

Publication number: EP1996760A1
Application number: EP07705250A
Authority: EP
Inventors: David Toms
Original assignee: DYLON INTERNATIONAL Ltd
Current assignee: DYLON INTERNATIONAL Ltd
Priority date: 2006-03-15
Filing date: 2007-02-21
Publication date: 2008-12-03
Also published as: GB0605260D0; WO2007104916A1

Abstract

A composition for the whitening of polyester, comprising an optical brightening agent for polyester and a carrier selected from the group consisting of an alkylphthalimide derivative or mixture of alkylphthalimide derivatives, an aromatic ester, an aromatic salicylate and dipentene, and mixtures thereof.

Description

WHITENER FOR POLYESTER FABRICS

The present invention relates to a product for whitening fabric articles. In particular the invention is directed towards a product for whitening articles which are made of or include some polyester in a mix.

Optical Brightening Agents (OBAs) have been used for many years to 'boost' the whiteness of natural and man-made fibres. In order to be a true white, a fibre would need to reflect 100% of the light within the visible region of the spectrum. In practice, however, it is difficult to achieve this and therefore a number of attempts to artificially improve whiteness have been tried over many years. Bleaching, for example, is often used to try and improve whiteness of materials, but this can in practice result in a yellow tint. Optical brighteners have therefore been used, either with or after the bleaching process to try and minimise this problem.

Optical brighteners (or Fluorescent Whitening Agents as they are also known) absorb the invisible ultra-violet radiation in light and re-emit part of this energy in the visible spectrum, usually in the blue — violet region. This conversion of invisible ultra-violet radiation into a reflected visible light makes the fibres look 'unnaturally white'.

OBAs are available for all the major fibre types including cotton, polyester, nylon, wool and silk. As well as being used in the manufacture of textiles and paper for example, they are also commonly used in domestic laundry detergents, stain removers and whiteness boosting products to boost the whiteness of already white items. However, it is very difficult to apply OBAs to polyester fibres. This is due to polyester fibre having a lack of reactivity and a highly compact, crystalline structure. Polyesters are a general group of polymers derived from terephthalic or adipic acids, for example polyethylene terephthalate.

Industrially, OBAs have been and are generally still applied to polyester at high temperatures (substantially above 100⁰C) and elevated pressure. Examples of such processes are set out in US4283197 where the temperature of operation is preferably in the range 100-130⁰C, GB 1052355 which has an even higher temperature range of 180 to 22O⁰C for the brightening of the polyester fibres, and GB 1485555 which has a temperature of 150-230⁰C.

Other prior art processes for the industrial application of OBAs to polyester reduce the temperature of operation slightly further by the use of 'carriers' to a temperature in the range 80-99°C. Such carriers include hazardous compounds such as orthophenylphenol, biphenyl, 2-hydroxybiphenol and 1,2,4- trichlorobenzene. It is not certain exactly how these 'carriers' work, but one suggestion is that they seem to cause the polyester fibres to swell, allowing the OBA into the polyester's compact structure.

Both of these methods are for industrial use and would not be practical for domestic use for two main reasons: firstly the high temperatures involved, and secondly the highly hazardous nature or pungent odour of the 'carriers' sometimes used. Therefore existing laundry detergents and whiteness boosters for domestic use generally contain OBAs for cotton with additional OBAs sometimes being added for wool, silk and nylon but not for polyester.

The present invention seeks to overcome the problems of the prior art. A first object is to provide a product for the whitening of polyester. According to the present invention, there is provided a composition for the whitening of polyester, said composition comprising an optical brightening agent for polyester and a carrier selected from the group consisting of an alkylphthalimide derivative or mixture of alkylphthalimide derivatives, an aromatic ester, an aromatic salicylate and dipentene, and mixtures thereof.

Optionally, the optical brightening agent for polyester is selected from stilbene derivatives, benzoxazole derivatives, coumarin derivatives, carbostyril compounds, combined heteroaromatics and naphthalimides. In particular, the optical brightener for the polyester may be selected from 2,2'-vinylenebis [5- methylbenzoxazole] (Hostalux ™ EF by Clariant ™ International Limited ), or 7- (2H-naphtho[l,2-d]triazol-2-yl)-3-phenylcoumarin (Leucophor ™ EGA by Clariant International Limited ).

The carrier may optionally be selected from the group consisting of N- butylphthailimide, butyl benzoate, phenyl salicylate, dipentene and other alkylphthalimide derivatives or mixtures thereof.

The composition may further comprise optical brighteners for one or more of cotton, wool, nylon or silk. These may act alongside the brightener for polyester in cases where there are' mixtures of material, for example polyester/cotton mixes or clothing items which have different fabrics being used within the same product.

The composition may also act as an optical brightener for acrylic fibres. Traditional OBAs for acrylic fibres are cationic and therefore differ substantially from the anionic brighteners used for cotton, nylon etc. The compositions of the present invention will brighten acrylic fibres even in the presence of other anionic optical brighteners, thereby providing the facility to brighten a wider range of fabrics in one treatment than had previously been possible.

The composition may also further comprise one or more surfactants which may be an anionic, a non-ionic or an amphoteric surfactant. The composition may further comprise one or more of the following: enzymes, bleaches, dye transfer inhibitors, water softeners and perfumes. The function of each of these additional components is well known to the person skilled in the art and any known compounds may be employed.

The polyester optical brightening agent is present at a concentration to be effective and this may vary depending on the exact nature and condition of the polyester to be treated. Typically, the brightener will be present at a level of at least 0.01% o.w.f. (on weight of fabric expressed as a percentage). The polyester optical brightening agent may be present at a concentration in the range 0.001 to 4% o.w.f., or in the range 0.01 to 2% o.w.f., or in the range 0.01 to 1% o.w.f., or in the range 0.015 to 0.5% o.w.f., or in the range 0.02 to 0.1% o.w.f.

The concentration of the carrier is at least 0.05% o.w.f. and may be in the range 0.05 to 15% o.w.f., or in the range 0.1 to 10% o.w.f., or in the range 0.1 to 5% o.w.f., or in the range 0.2 to 2% o.w.f.

The ratio of the polyester optical brightening agent to the carrier may be in the range 1:2.5 to 1:500 to produce visually noticeable results on treatment of a polyester fibre. The ratio may be in the range 1:10 to 1:250, or in the range 1:50 to 1:200, or in the range 1:75 to 1:125. The invention also extends to a method of treatment to whiten a polyester article, in which the polyester article or article containing polyester fibres is treated with a composition as set out above. A preferred treatment method comprises the steps of washing the article in a conventional washing cycle including the polyester whitening composition as set out above. The washing cycle may be run at a temperature in the range 10 to 60⁰C, or 20 to 6O⁰C, or 20 to 50⁰C and optionally at a temperature in the range of 20 to 40⁰C. Other optional features of the composition set out above apply equally to the method of the invention.

The present invention may be put into practice in a number of different ways and various embodiments will be described here in further detail by way of non-limiting example.

Example 1 : comparison with commercially available products

A polyester whitening formulation according to the present invention was made This results in a composition as follows (percentages are weight/weight)

Composition 1

0.40% Hostalux ™ EF (Clariant - contains 2,2'-vinylenebis[5- methylbenzoxazole])

0.05% Tinopal ™ CBSX (Ciba)

0.32% Tinopal ™ DMSX (Ciba) 0.50 % Leucophor ™ BSB Liquid (Clariant)

0.04% Tinolux ™ BBS (Ciba)

20.00% N-butylphthailimide

23.00% non-ionic surfactant (PEG-7 C 10 oxo alcohol)

22.00% sulphated castor oil 0.10% perfume

33.59% water

The performance of this formulation ("Composition 1") was tested against various products on the market that claim to whiten laundry in the domestic environment.

In each case 50Og of 100% polyester which had been scoured but had no OBAs applied was washed in a domestic washing machine (Miele ™ Softronic W418) at 40⁰C with the following additions: -

1. Ariel ™ (laundry detergent) - 14Og

2. Eau Ecarlate Reblanchisseur (whiteness booster) - 25g

3. GIo- White ™ Super Whitener (whiteness booster) - 4Og 4. "Composition 1" — (whiteness booster) — 25ml

In cases 2, 3 and 4, the 'whiteness booster' was used with a laundry detergent (in this case the Ariel detergent used in test (I)), as per their instructions All of the products above either claim to whiten fabrics domestically or include OBAs in their ingredient listing.

After treatment, the polyester was allowed to dry naturally and then its whiteness was measured using a TFT OBA Meter (see below) and compared to the untreated polyester - see Table 1 below.

OBA Meters measure the Fluorescence of fabrics by comparison against standard calibrated reference papers. Before the OBA Meter is used, the machine is calibrated against the papers that are to be used. The reference papers give a calibrated value on the front cover. Test Method:

1) The OBA machine is switched on and left for approximately 10 - 15 minutes to equilibrate.

2) The instrument is placed on to white calibrated reference papers, and using the dials on the top of the instrument the digital display is adjusted to read the same as the calibrated reference reading on the front cover (the right hand-side dial is for approximate tuning, the left dial is for precise tuning).

3) The fabric under test should be 4 x thickness to ensure that the reference paper fluorescence does not interfere with fabric fluorescence reading.

4) The fabric is placed under the light source and the reading is given on digital display, this is the Fluorescence Value of that fabric.

A value of zero on the TFT fluorescence would be completely black (i.e. no reflection of light) whereas a really good white on cotton may give a reading around 90. Within this range, a significant difference in whiteness can be detected by the human eye when there is a difference of 4 or 5 or more in the TFT measurements.

TFT OBA Meter Readings:

Table 1

It can be seen from the results that the products on the market (1.1 — 1.3) give effectively no whitening of the polyester, while the composition of the present invention (Composition 1) gave a significant effect. Examples 1.2 and 1.3 using the laundry detergent of 1.1 and a whitener booster gave TFT OBA readings less than that for the laundry detergent alone, but they probably fall within the experimental error range for the OBA machine. In any event, the samples showed no visible whitening of the polyester.

By contrast the fibre treated according to the present invention was visibly substantially whiter than both the untreated fibre and the fibres treated by using existing products. This is confirmed by the substantially higher TFT OBA reading for example no. 1.4. If the fibre was treated again using the composition of the present invention, the whitening effect would be cumulative and the sample would have a further increased whiteness. Example 2: Effect of Temperature

The same test method as described above was used but in a Bosch ™ WFF 120L washing machine, at various temperatures to test the effect of temperature on the composition made according to the present invention (Composition 1).

Table 2

The fabrics treated with a composition according to the present invention show a substantial increase in whiteness even at a temperature of 30⁰C. As expected, at the substantially higher temperature of 95°C the effect is even more pronounced but in a domestic environment this has to be balanced against the desire to operate at generally lower temperatures for environmental and safety reasons.

Example 3: Effect of Concentration

As for example 2 the test method was the same as that for example 1 with the tests conducted in a Bosch ™ WFF 120L washing machine at 40⁰C The concentration of the carrier (N-butylphthailimide) and the polyester optical brightener (Hostalux ™ EF) were varied as set out in table 3 below and the fluorescence results were measured and compared with an untreated polyester sample.

Table 3

As can be seen from the results for example number 3.1, in the absence of the carrier and in the presence of just an OBA for polyester, the TFT OBA reading is similar to that for the untreated fibre and to that for obtained after treatment with existing products. When a carrier is added, even at a very low level the whitening performance is substantially improved and the TFT OBA value and visual appearance are markedly different from the untreated fibre (see example number 3.2).

A further increase in the concentration of the carrier results in a gradual increase in the whiteness. When the level of the OBA is increased substantially, there is an even more significant increase in the TFT OBA value (see example 3.6). This may be expected, but obviously comes at the cost of the brightening chemical. It is clear from the experiments which have been conducted that visually acceptable results are obtained at substantially lower levels of brightener than 0.40% o.w.f.

These examples are not limiting and it will be apparent to a person skilled in the art that the results from the experiments described above are not dependent upon the washing machine or wash cycle used. It is clear that the composition of the present invention is generally applicable to brightening of polyester, in particular in a domestic environment.

Claims

1. A composition for the whitening of polyester, said composition comprising an optical brightening agent for polyester and a carrier selected from the group consisting of an alkylphthalimide derivative or mixture of alkylphthalimide derivatives, an aromatic ester, an aromatic salicylate and dipentene, and mixtures thereof.

2. A composition as claimed in claim 1, in which the optical brightening agent for polyester is selected from stilbene derivatives, benzoxazole derivatives, coumarin derivatives, carbostyril compounds, combined heteroaromatics and naphthalimides.

3. A composition as claimed in claim 2, in which the optical brightener for polyester is selected from 2,2'-vinylenebis[5-methylbenzoxazolej, and 7-

(2H-naphtho[ 1 ,2-d]triazol-2-yl)-3 -phenylcoumarin.

4. A composition as claimed in any preceding claim, in which the carrier is selected from the group consisting of N-butylphthailimide, butyl benzoate, phenyl salicylate, dipentene, and other alkylphthalimide derivatives and mixtures thereof.

5. A composition as claimed in any preceding claim, further comprising optical brighteners for one or more of cotton, wool, nylon or silk.

6. A composition as claimed in any preceding claim, further comprising one or more surfactants.

7. A composition as claimed in claim 6, in which the surfactant is selected from an anionic, a non-ionic and an amphoteric surfactant.

8. A composition as claimed in any preceding claim, further comprising one or more of the following: enzymes, bleaches, dye transfer inhibitors, water softeners and perfumes.

9. A composition as claimed in any preceding claim, in which the polyester optical brightening agent is present at a concentration of at least 0.001% o.w.f.

10. A composition as claimed in claim 9, in which the polyester optical brightening agent is present at a concentration in the range 0.001 to 4% o.w.f.

11. A composition as claimed in claim 9, in which the polyester optical brightening agent is present at a concentration in the range 0.01 to 2% o.w.f.

12. A composition as claimed in claim 9, in which the polyester optical brightening agent is present at a concentration in the range 0.01 to 1% o.w.f.

13. A composition as claimed in claim 9, in which the polyester optical brightening agent is present at a concentration in the range 0.015 to 0.5% o.w.f.

14. A composition as claimed in claim 9, in which the polyester optical brightening agent is present at a concentration in the range 0.02 to 0.1% o.w.f.

15. A composition as . claimed in any preceding claim, in which the concentration of the carrier is at least 0.05% o.w.f.

16. A composition as claimed in claim 15, in which the concentration of the carrier is in the range 0.05 to 15% o.w.f.

17. A composition as claimed in claim 15, in which the concentration of the carrier is in the range 0.1 to 10% o.w.f.

18. A composition as claimed in claim 15 , in which the concentration of the carrier is in the range 0.1 to 5% o.w.f.

19. A composition as claimed in claim 15, in which the concentration of the carrier is in the range 0.2 to 2% o.w.f.

20. A composition as claimed in any preceding claim, in which the ratio of optical brightening agentxarrier is in the range 1:2.5 to 1:500.

21. A composition as claimed in claim 20 , in which the ratio is in the range 1:10 to 1:250

22. A composition as claim in claim 20 , in which the ratio is in the range 1 :50 to 1:200

23. A composition as claimed in claim 20 , in which the ratio is in the range 1:75 to 1:125.

24. A method of treatment to whiten a polyester article, in which the polyester article is treated with a composition as claimed in any preceding claim.

25. A method of treatment as claimed in claim 24 , in which the treatment comprises the steps of washing the article in a conventional washing cycle including a composition as claimed in any one of claims 1 to 23.

26. A method of treatment as claimed in claim 25, in which the washing cycle is at a temperature in the range 10 to 60⁰C.

27. A method of treatment as claimed in claim 25, in which the washing cycle is at a temperature in the range 20 to 60⁰C.

28. A method of treatment as claimed in claim 24, in which the washing cycle is at a temperature in the range 20 to 50⁰C.

29. A method of treatment as claimed in claim 25, in which the washing cycle is at a temperature in the range 20 to 40⁰C.