Water-free preparation and use thereof as sewing yarn finish

Abstract

The present invention relates to water-free preparations and their use as a sewing yarn finish which comprise (1) 70-98% by weight of a polydialkylsiloxane, (2) 1-29% by weight of a paraffin wax, (3) 0-6% by weight of a fatty acid having 8-22 carbon atoms, (4) 0-6% by weight of a fatty acid ester having 8-22 carbon atoms in the fatty acid radical and 3-22 carbon atoms in the fatty alcohol radical and also (5) 1-5% by weight of a mediator.

Description

BACKGROUND

[0002] A water-free preparation and its use as a sewing yarn finish are disclosed.

[0003] It is known that sewing yarns are finished with preparations which are composed of silicone oils, paraffins and other additives and which endow the finished yarn with particular slip and friction properties in order that it may withstand the high stresses of the sewing operation.

[0004] There are various causes for the extremely high stress on the sewing yarn. The following parameters are key: the yarn drag (dependent on the braking force set at the sewing machine); the force due to the yarn take-up spring; the frictional forces arising at points of deflection; the continual changes in load on the sewing yarn; and also the inertial forces which occur in the course of abrupt accelerations. Industrial sewing machines in use today operate at between 6000 and 12000 sewing cycles per minute and pull a defined yarn piece through the eyelet of a needle at up to 60 times per cm of seam. This results in extremely high rubbing and scuffing forces, not only due to the contact of the individual fibre of the yarn with sewing machine parts, especially the eyelet of a needle, but also due to the rubbing of the individual fibres against each other within the fibre assembly during loop formation.

[0005] Owing to the high sewing speed, various machine parts heat up to 400° C. as a result of friction due to the material to be sewn. This applies in particular to the sewing needle on piercing through the material to be sewn, to the frictional contact between the metal of the sewing needle and the woven knitted fabric of the substrate to be sewn or else to the take-up lever. The machine parts which are in direct contact with the sewing yarn and heat up to extremely high temperatures as a result of friction are particularly critical for sewing yarns composed of synthetic materials, for example polyamide (PA) or especially polyester (PES). Their softening range at 210-250° C. according to provenance is so low that sewing needle temperatures of above 300° C. lead to incipient melting and hence rupture of the sewing yarn. This applies especially to sewing multiple layers of closely woven material, such as denim articles (jeans) etc.

[0006] To improve the resistance of the sewing yarn to the stresses described, it is customary to finish the sewing yarn with compositions which contain paraffin wax as a surface-smoothing component and also polydimethylsiloxanes to reduce the transfer of the heat of friction from the sewing needle to the sewing yarn substrate.

[0007] However, mixtures of the lubricant components paraffin and polydimethylsiloxane and also any other additions such as, for example, fatty acids and esters and also any antistats are not stable at ambient temperature, but form heterogeneous, coarsely disperse systems which tend to separate into plural phases during storage. A continuous, homogeneous phase will customarily only appear at temperatures above the melting point of the hydrocarbonaceous components, i.e. usually above 70° C. Consequently, the preparations have to be applied to the sewing yarn at these high temperatures in order that the constant ratio between the individual components of the finish (which is necessary to achieve optimal sewing results) may be achieved and transferred to the sewing yarn. This prior art method of application is known as “hot melt”.

[0008] EP-A-0340575 describes water-free preparations which are composed of polydimethylsiloxane and a fatty acid or a fatty amine and also customary additives and which constitute clear, homogeneous solutions at a temperature of 45° C. On cooling to ambient temperature, however, the hydrocarbonaceous fractions in the preparations reprecipitate and lead to pasty or waxy products, depending on the composition.

[0009] DE-C-196 15 983 describes water-free preparations consisting of 65- 95 parts by weight of polydimethylsiloxane having 350 to 5000 mPa·s at 25° C. and 35 to 5 parts by weight of paraffin which is solid or liquid at ambient temperature and also a compatibilizer consisting of an alkyl- or alkoxy-terminated polydimethylsiloxane. The addition of the compatibilizer is intended to ensure that clear, homogeneous mixtures are formed and that there is none of the customary separation on cooling preparations composed of silicone oil and paraffin. And indeed: when such preparations utilize the silicone oils having viscosities>350 mPa·s that are necessary for optimal coefficients of friction and sewability as well as paraffins having melting points between 40 and 60° C., the compatibilizer added prevents any separation on cooling of the preparation. However, the mixture is pasty or creamily solid, depending on the type of compatibilizer used. Such preparations can therefore only be applied from heated galettes or specific applicators.

[0010] To obtain preparations which can be applied also at room temperature, EP-A-0474467 utilizes mixtures of polydimethylsiloxane and paraffin wax emulsions in an aqueous phase. Such preparations are liquid at ambient temperature and can be applied to sewing yarn by means of a galette. However, the water content needed to make the product liquid can cause corrosion on machine parts and also lead to increased viscosity or drying of the preparation due to evaporation during machine shutdowns when applied from a galette. Moreover, because of the content of water, subsequent drying of sewing yarn spools is indispensable if moulding during storage is to be avoided.

[0011] EP-A-0900876 describes a fibre treatment agent based on a dispersion of magnesium soap dispersed in a polydimethylsiloxane of viscosity range 5-50 mPa·s by means of a dispersant mainly consisting of a carboxyamide-modified silicone; this carboxyamide-modified silicone has at least one free carboxyl group which in each case is bonded to the polysiloxane chain via a carboxamide group. This treatment agent is intended to increase the coefficient of friction between polyurethane fibres.

[0012] All of the foregoing mentioned patent documents are hereby incorporated by reference in their entireties.

SUMMARY

[0013] A water-free preparation is disclosed which is liquid at ambient temperature and which is suitable for finishing sewing yarn at ambient temperature or only minimally elevated temperatures. At the same time, the sewing performance properties to be achieved, especially a low coefficient of friction and good sewability on the part of the sewing yarn, can be superior to those of the prior art as represented by aqueous finish formulations.

[0014] Surprisingly, this performance profile is achieved by a preparation which, as well as prior art components, includes a mediator which reduces the viscosity of exemplary preparations described herein to such an extent that application by means of a galette is possible at ambient temperature or only insignificantly elevated temperatures. Exemplary preparations do not separate in the process, but remain intact as a homogeneous dispersion depending on the composition chosen. At the same time, the technological properties of the sewing yarn, such as coefficient of friction and sewability, can be improved over the prior art.

DETAILED DESCRIPTION

[0015] According to exemplary embodiments of the invention there are now provided, in a first aspect, water-free preparations comprising (based on total composition)

(1)	70-98% by weight	of a polydialkylsiloxane
		having trimethylsilyl and/or
		hydroxyl end groups and a
		viscosity of 50-10000 mPa · s,
(2)	1-29% by weight	of a paraffin wax,
(3)	0-6% by weight	of a fatty acid having 8-22
		carbon atoms,
(4)	0-6% by weight	of a fatty acid ester having
		8-22 carbon atoms in the fatty
		acid radical and 3-22 carbon
		atoms in the fatty alcohol
		radical and also
(5)	1-5% by weight	of a mediator of the formula (I)

[0016] 1

[0017] or of the formula (II) 2

[0018] where n and m are integers, n in the formula (I) and the sum total of n and m in the formula (II) are between 2 and 50, the ratio of n:m in the formula (II) is between 1:1 and 49:1 and the radical R1 is 3

[0019] where R3=—H, —CH3; X=—OR4 or —NHR4; the radical R4=—H, —Na, —K, —NH4, -alkyl of 2-22 carbon atoms or -phenyl and the radical R2 in the formula (II) consists of —CH3 or —OH.

[0020] All the indicated weight figures for exemplary preparations disclosed herein are based on the overall composition of the inventive preparation. Preferred ranges are a range of 75-95, more preferably of 90-95% by weight for component (1) and 1-20 but especially 1-10% by weight for component (2). When components (3) and (4) are added, their concentration is preferably in the range of 1-6 and especially 1-3% by weight. The concentration of component (5) is in a range of 1-5 and preferably 1-3% by weight.

[0021] Component (1) consists of polydialkylsiloxane having trimethylsilyl and/or hydroxyl end groups which has a viscosity of 50-10 000 mPa·s. Preference is given to using linear polydimethylsiloxanes having trimethylsilyl and/or hydroxyl end groups. The lateral methyl groups, however, can also be replaced by other organic alkyl or aryl groups. Ethyl and phenyl groups can be contemplated as such, for example. Component (1) can in unitary form preferably consist of polydimethylsiloxane or α,ω-dihydroxy-terminated polydimethylsiloxane and also of mixtures of the two. The production of polydialkylsiloxanes for component (1) will be known to one skilled in the art and is described for example by Noll, “Chemie+Technologie der Silicone” p. 162 ff. or Houben-Weyl, “Methoden der organischen Chemie” E 20/3 p. 221 ff.

[0022] For preparations to be applied to sewing yarn by means of a galette, they have to have a very low viscosity. It is therefore preferable to use silicone oils which have ambient temperature viscosities of 50-10000 mPa·s and especially 1000-5000 mPa·s.

[0023] Component (2) of the preparation consists of a paraffin wax. The wax can consist of the customary, well-known hydrocarbons from a wide range of provenances. Not only natural waxes, such as beeswax and carnauba wax, but also synthetic waxes such as polyethylene wax and Fischer-Tropsch waxes can be used. However, particular preference is to be given to linear paraffin waxes with or without a 1-5% by weight fraction of short-chain linear hydrocarbons which are liquid at ambient temperature.

[0024] Optimal melting points for the paraffins used are known from the prior art. For instance, low-melting paraffins having a melting point <50° C. give distinctly better coefficients of friction than those having melting points >60° C. Particular preference is therefore to be given to paraffin waxes having a melting range of 40-70° C., but especially to those having a melting range of 46-58° C.

[0025] Component (3) of the exemplary preparation preferably consists of aliphatic, unbranched, saturated or unsaturated carboxylic acids. The composition can preferably include fatty acids having 14-20 carbon atoms and particularly having 16-18 carbon atoms in the fatty radical. In the case of unsaturated fatty acids, they can contain one or more double bonds in the fatty radical. Embodiments can also utilize plural fatty acids which differ from each other. The production of fatty acids for component (3) will be known to one skilled in the art and is described for example in Ullmann's Encyclopaedia of Industrial Chemistry (5th edition) A10, p. 254 ff.

[0026] Component (4) in the exemplary preparation preferably has 10-22 carbon atoms but more preferably 14-18 carbon atoms in the acid radical. The fatty acid radical can be linear or branched and can also contain one or more double bonds. It may be preferable for the fatty alcohol radical to contain 3-18 carbon atoms, in which case the radical may be linear, but especially branched. The production of fatty acid esters for component (4) will be known to one skilled in the art and is described for example in Ullmann (5th) A9, p. 572 ff.

[0027] Component (5) in the exemplary preparation comprises compounds which lower the viscosity of exemplary preparations to such an extent that use is possible at ambient temperature or only insignificantly elevated temperatures. Ambient temperature is to be understood as meaning temperatures of 20-45° C. Exemplary preparations do not separate during their use, but remain intact as homogeneous dispersions, depending on the composition chosen. The production of the mediator for component (5) will be known to one skilled in the art and may be carried out for example similarly to Examples 1 to 9 of EP-A-0 955 340. The integers n in the formula (I) are preferably between 2 and 10, the integers of the sum total of n and m in the formula (II) are preferably between 25 and 50. The ratio of n:m in the formula (II) is preferably in a range of 5:1 and 25:1. The radical R4 is preferably embodied as an alkyl radical having 10-18 carbon atoms.

[0028] As well as the components mentioned, further components can be added in order that particular effects may be achieved. For instance, small fractions of organic phosphorus compounds and especially of organic-modified phosphoric esters can improve the electrostatic properties of finished sewing yarns. When the yarns are to acquire a biostatic or biocidal property, this can be achieved by adding 0.1-0.2% by weight of isothiazolinone derivatives.

[0029] Exemplary advantages of the preparations disclosed herein include first in a distinct reduction in the coefficient of friction of sewing yarns finished therewith and secondly in a lowering of the heat of friction due to the sewing operation in the region of the needle eyelet and also of other machine parts in contact with the sewing yarn, distinctly lowering the tendency of a yarn to break during sewing. A further advantage resides in the low viscosity of the preparation whereby application to the sewing yarn is possible by means of a galette without the preparation having to be heated to beyond the melting point of individual components in order that a homogeneous phase may be achieved. However, depending on the type and amount of paraffin used and on the ambient temperature encountered, it can be necessary to minimally raise the temperature to 35 to 45° C.

[0030] Owing to the significantly lower application temperatures compared with the conventional “hot melt” process, which is carried out at temperatures between 70 and 90° C., appreciable energy savings can be achieved through partial or complete elimination of the heating for the galette system. Since, moreover, the exemplary preparation contains no added water, the disadvantages associated with added water, such as corrosion of machine parts, increased viscosity for the preparation due to drying out or mould forming on finished sewing yarns are avoided. Exemplary preparations can at most contain traces of water, which are entrained as impurities with the ingredients used. The amount of any entrained water is not more than 0.5% by weight and preferably not more than 0.1% by weight.

[0031] Exemplary preparations are produced by simply mixing the components indicated in the claim together at temperatures above the melting point of the individual components and then cooling to ambient temperature.

[0032] The invention further provides for the use of inventive preparations as a sewing yarn finish.

[0033] Preparations disclosed herein are very useful for application to sewing yarns to lower the coefficient of friction and the heat of friction due to the sewing operation in the region of the needle eyelet and of other machine parts in contact with the sewing yarn. The sewing yarns can consist of natural fibres and/or synthetic fibres, especially PES and PA fibres. In the case of synthetic yarns, these can have been produced not only from staple fibres but also from monofil fibres. Trilobal synthetic yarns can be employed for the specific field of embroidery yarns. Application is conveniently done from the galette familiar to one skilled in the art, in which case exemplary preparations are fed from a heated or unheated storage vessel by means of pump systems via likewise heated or unheated lines to the galette trough. Application can take place at ambient temperature or, if necessary, minimally elevated temperature at 35-45° C., depending on the composition of the inventive preparation.

[0034] Add-on levels in the range between 2 and 20% by weight based on sewing yarn weight can be employed for preparations disclosed herein, depending on yarn type and the intended use of the sewing yarn.

[0035] The examples which follow illustrate embodiments of the invention (cf. table hereinbelow). The sewing yarn finish was applied by means of a laboratory instrument. The viscosity numbers reported in the third row from the end of the table are based on the viscosity of the preparations used and were determined at 23° C. using a VT 500 viscometer from Haake of Karlsruhe (SVDIN measuring body). The coefficients of friction were determined using an “Anchor Friction Tester” from Kerr & Co.

[0036] Sewability was tested on a Dürkopp 211-5 lockstitch sewing machine with intermittent drop feed as per the following method:

[0037] Five layers of a plain-woven PAC awning fabric were placed on top of each other in the warp direction and stitched together at one end. A starting line was drawn at right angles to the warp direction at about 2 cm from the stitched end. Strips 10 cm in width (weft direction) and 30 cm in length (warp direction) were cut from this fabric and used for an individual test one at a time. The test fabric was fed loosely during the sewing test. The upper thread tension was set to an optimal seam having a stitch length of 4 mm. Sewing machine settings were kept constant during test sewing. Sewing was done at 5000 stitches/min until the yarn broke. A new needle was used for each seam in order that the influence of deposits on the needle might be eliminated. After the yarn broke, the length of the stitched seam from the starting line to the yarn breakage point was measured out in cm. Owing to the high measured value scatter, 15 individual seams were produced for each test, with the lowest and the highest value and also unclean seams being excluded from evaluation. The remaining results were averaged.

[0038] Examples (table):

		Comp.	Inv.	Inv.	Inv.	Inv.	Inv.	Inv.	Inv.
Component	Untreated	example	example 1	example 2	example 3	example 4	example 5	example 6	example 7
(1) PDMS		90.0	88.0	76.0	76.0	86.0	86.0	95.0	92.0
1000 mPa · s
(2) Paraffin		5.0	5.0	20.0	20.0	10.0	10.0	1.0	6.0
46/48
(3) Stearic		2.5	2.5	—	—	—	—	—	1.0
acid
(4) Butyl		2.5	2.5	2.0	2.0	2.0	2.0	2.0	—
stearate
(5) Mediator of		—	2.0	—	—	2.0	—	2.0	1.0
formula (I)1
(5) Mediator of		—	—	2.0	—	—	2.0	—	—
formula (I)2
(6) Mediator of		—	—	—	2.0	—	—	—	—
formula (II)3
Appearance		highly	viscous,	viscous,	viscous,	viscous,	viscous,	transparent	viscose,
		viscous	liquid	disperse	disperse	liquid	liquid		disperse
Viscosity [mPa · s]		10000	3000	6000	5800	1800	1560	900	4000
Coefficient [μ]	0.280	0.196	0.186	0.185	0.198	0.183	0.185	0.182	0.190
of friction
Sewability Seam	3	10	11	8	7	12	13	13	12
test length
[cm]
1n = 10, R1 = group (III), R3 = —H, X = —OR4, R4 = —C22H45
2n = 8, R1 = group (IV), R3 = —CH3, X = —OR4, R4 = —C18H37
3n = 30, m = 2, R1 = group (V), R2 = —OH, R3 = —H, X = —NHR4, R4 = —C18H37

[0039] It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.

Claims

1. A water-free preparation comprising, based on total composition:

2. Use of a preparation as recited in claim 1 as a sewing yarn finish.

3. A water-free preparation comprising, based on total composition:

4. A water-free preparation comprising, based on total composition: