EP0123794A2 - Method of making a non woven stretch filler fabric - Google Patents

Abstract

The fabric with a density of 0.005 to 0.05 g/cm<3> is produced by processing the latent crimp fibres into a fibre web with or without needling, spraying with a binder and then drying at a temperature at which no crimping of the fibres occurs, then initiating the crimping of the fibres and thus causing the web assembly to shrink, with the proviso that the web comprises at least 30 % by weight of latent crimp fibres or fibre blends and, if desired, less than 30 % of thermal binding fibres.

Description

The invention relates to a method for producing an elastic, non-woven filler or cushioning material with a density of 0.005 to 0.05 g / cm ³ according to the preamble of claim 1.

A method of this type is known from EP-OS 42 150. In this case, a nonwoven made of a fiber mixture with low-melting, shrinkable and higher-melting, crimpable fibers is subjected to a heat treatment such that the temperature lies between the softening temperatures of the two types of fibers. As a result, the low-melting component shrinks, the higher-melting component ripples and a bulky padding material is created by these processes. The softening of the low-melting fibers leads to an adhesive binding at the fiber crossing points.

The method mentioned requires an exact temperature control with respect to each point of the nonwoven, since even slight deviations negatively influence the melting, shrinking and crimping behavior of the fiber components. Furthermore, the simultaneous laying down of two types of fibers in a defined spatial and quantitative relationship to one another can only be achieved with a high outlay in process control during spinning and during the formation of nonwovens.

A method using only one shrinkable type of fiber is described in EP-OS 38 887. The bonding of the fibers in the nonwoven is achieved in that shrinked and crimped fibers are sprayed with a hot melt adhesive before being deposited into a nonwoven. After storage, the surface of the filler nonwoven thus formed is sprayed again with binder in a further process step. Subsequent thermal softening of the binder creates a bond between the fibers at their crossing points and on the nonwoven surface. Then the crimping of the fibers by heating fixed and the binder stabilized at the same time. A disadvantage here is the fact that the individual fibers remain stiff despite their crimping, since the binder is located on the entire outer surface of the fibers after shrinkage and thus blocks a resilient movement. This has a negative effect on the stretchability of the filler nonwoven. Furthermore, the relatively high amount of binder causes sticking at too many places in the fiber fabric, which leads to stiffening and irregularities in the filler; this limits its possible use, for example in sports clothing, where high flexibility is required.

DE-AS 12 20 141 contains a method in which a nonwoven fabric made of latent shrinkable or crimpable fibers is solidified solely by needle treatment and then shrunk. However, this method is only suitable for the production of compact felt materials and would in no way guarantee the required cohesion of the fibers when applied to bulky fillers.

The invention has for its object to develop a method of the type mentioned in such a way that the disadvantages mentioned are avoided. In addition to simplifying the manufacturing process, the method is intended in particular to provide a filler or upholstery material whose softness, bulk and extensibility outperforms the products previously manufactured using similar methods. These properties should go hand in hand with such a strength that the fillers, even as wadding in sports clothing, can withstand high loads with regard to tensile, compressive and crushable properties. Furthermore, the thermal insulation qualities important for this area of application are to be improved at the same time.

This object is achieved according to the invention by the specified claims.

According to the proposed method, a non-woven filler or upholstery material with a density of 0.005 to 0.05 g / cm ³ is obtained by forming a nonwoven scrim with a proportion of at least 30% by weight of latently crimpable fibers and a binder on both sides this fleece sprays, the fleece dries at a temperature below which there is no crimping of the fibers, and then the shrinkage of the fleece is initiated by subjecting the fibers to a crimping process.

All synthetic organic continuous threads and / or staple fibers can be used as latent crimpable fibers, provided that they can be shortened to a substantial extent by at least 15%. The shortening should preferably be done by crimping.

Side-by-side bicomponent fibers whose polymer components differ from one another in their thermal behavior can preferably be used among the various types of crimpable fibers that can be used for the present method.

Other preferred thermoplastic fibers are those which are heat-set in their manufacture in a highly twisted state and are then untwisted at a lower temperature.

A third preferred type of fiber consists of edge-shrunk yarn. These are fibers whose crimpability is based on one-sided molecular orientation disorders.

Since the extensibility of each upholstery material is generated by the crimping of the fibers contained in it, an increase in the number of crimped fibers must lead to an improvement in the achievable stretching properties of the filler. As a result, those types of fibers will form a particularly valuable product whose crimp rate per unit length is high.

According to the invention, the fleece is produced by carding or carding. The fiber structure should consist of at least 30% by weight, preferably more than 50% by weight, of latent crimpable fibers. Falling below the value of 30% by weight leads to products with insufficient stretchability. The greater the proportion of latent crimpable fibers, the better the upholstery fabric behaves in terms of its stretchability. In order to obtain particularly good elongation values, a fleece will be used that consists entirely of latent crimpable fibers. Otherwise, the crimpable fibers in a fiber mixture should contain as many crimps as possible, provided that the carding process or the uniformity of the fleece are not impaired thereby. Fibers with a low number of crimps negatively influence the elasticity of the filler.

A preferred process variant includes a needling process after the fleece has been laid.

After carding or carding and optionally needling, a binder, for example acrylic resin emulsion, is applied to the nonwoven by means of a spraying device. Good values for stretchability, thickness elasticity and bulk are only achieved if the adhesive dots are distributed three-dimensionally; therefore a spraying process is necessary. In connection with this spraying process, hot melt adhesive fibers can also be used the fleece must be mixed in to achieve a three-dimensional adhesive dot distribution. When using this method, however, there is the possibility that the hot-melt adhesive fibers soften again during the crimping process and thereby glue already shrunk fibers to others, which impairs the stretchability of the end product. Such hot melt adhesive fibers may therefore only be added in small numbers. The three-dimensional distribution of the adhesive dots can preferably also be ensured by spraying the fleece on both sides with adhesive.

After the adhesive treatment, the nonwoven fabric is subjected to drying in order to achieve the necessary fiber-fiber bond. According to the invention, the temperature must in no case reach the values which initiate crimping, since otherwise uneven shrinkage would result in the fiber composite as a result of simultaneous gluing and crimping, which would result in undesired deformation and / or inadequate elongation properties of the end product.

After the drying process, the crimping process of the fibers is initiated. This can be done, for example, by the action of heat below the melting point. In order to maintain the stretching behavior and bulkiness of the product, no tension should be exerted on the nonwoven that would hinder its shrinking in one direction.

The fiber density of the resulting filler or upholstery material should be 0.005 to 0.05 g / cm ³ , preferably 0.1 to 0.03 g / cm ³ in view of thermal insulation properties and tensile strength, The nonwoven filling and cushioning nonwovens produced according to the above procedure are characterized by high values for bulk and elasticity. Furthermore, the fact that, according to the invention, a large number of fiber crimps remain unbound, the stretching behavior is uniform and satisfactory on all sides. A further advantage consists in the agreement that by the binder-spraying high Waschbeständi ^g ness of the product, which is particularly for use in sports and winter clothing beneficial. Due to the excellent thermal insulation properties, such fillers are also well suited for bedding, sleeping bags and gloves.

The invention is explained below using examples, which, however, are not intended to restrict the claims. In these examples, the "percent permanent set" is used as a measure of the stretchability. It is based on measurement data according to the Japanese standard JIS L-1080. Here, the sample is stretched to 40 degrees and then allowed to reform. After repeating this process ten times, the quotient is formed from the remaining length to the initial length of the sample and converted into percent.

example 1

50% by weight of 3 den polyester fibers with a fiber length of 51 mm and 7 crimps / cm (17 / inch), which were made crimpable by an edge shrinking process, and 50% by weight of highly crimpable 3 den polyester multicomponent fibers with a length of 51 mm and 7 crimps / cm (17 / inch) were mixed and then cross-laid Carding transferred into a fleece with a specific weight of 38 g / m ² . A polyacrylic ester emulsion was then sprayed on both sides of the scrim and the whole was then dried in a dryer at a temperature below 100.degree. At this point the fleece had a specific weight of 44 g / m ² . After drying was complete, the latent crimpable fibers were crimped using a dryer at 170 ° C with little or no pressure being applied to the fiber layer. The nonwoven began to shrink.

After this process, the fibers had a crimp of 13 crimps / cm (34 / inch) and the degree of shrinkage of the nonwoven was 17% in the longitudinal direction and 23% in the transverse direction. The resulting upholstery fabric had a specific weight of 70 g / m ² , a thickness of 7 mm and an apparent density of 0.01 g / cm ³ .

The permanent deformation, which is a measure of the stretchability of the upholstery material, was 25% in the longitudinal and 15% in the transverse direction. These values show a very good stretchability.

Furthermore, the filler showed good stretchability after dry cleaning, with values for the permanent deformation of 3.5% in the longitudinal direction and 2.0% in the transverse direction. So there was a high resistance to dry cleaning.

Comparative example

100% by weight of a highly crimpable multicomponent fiber of 3 den, 51 mm fiber length and 7 crimps / cm (17 / inch) were made into a fleece of 38 g / m ² by a cross-laying Carding process processed. Thereafter, as in Example 1, a polyacrylic emulsion was sprayed over both surfaces of the scrim and this was then dried at 150 ° C. using a dryer. The fleece weighed 44 g / m ² after this treatment.

The filler obtained in this way could not be measured for its longitudinal stretchability, since it did not withstand a 40% change in length and broke. In the transverse direction, too, there were poor tensile qualities with a residual deformation of 15%.

Example 2

100% by weight of side-by-side bicomponent fibers with 4 den and 51 mm length, consisting of a polyester component with a melting point of 210 ° C and a shrinkage starting temperature of 160 ° C and a polyester component with a melting point of 255 ° C and an initial shrinking temperature of 230 ° C. were processed into a nonwoven with 55 g / m ² and a thickness of 10 mm by means of an ordinary cross-laying card. The fleece then underwent needle treatment using a needle chair. A felt-like product with a thickness of 4 mm was obtained. A polyacrylic ester emulsion was sprayed onto both sides and the nonwoven fabric was then dried at 120 ° C. Its specific weight was then 63 g / m ² . After drying, the fibers were crimped using a heat shrinking apparatus; the fleece shrank 22% in the longitudinal direction and 38% in the transverse direction.

The cushion or filler thus obtained had a specific weight of 130 g / m ² , a thickness of 6 mm and an apparent density of 0.022 g / cm ³ . The percentage permanent deformation was 1.5 110 in the longitudinal direction and 1.0% in the transverse direction; the product therefore had better values than that in Example 1.

This improvement in strength through needle treatment makes the fillers produced according to the invention particularly suitable for use in sports clothing.

Claims (9)

1. A process for producing an elastic, non-woven filler or cushioning material with a density of 0.005 to 0.05 g / cm ³ , characterized in that a carded or carded nonwoven scrim with a proportion of at least 30% by weight of latently crimpable fibers sprayed with binder and then dried, the drying temperature being so low that there is no fiber crimping, and that the fleece is then subjected to a crimping process oriented on all sides. 2. A method for producing a filler or upholstery material according to claim 1, characterized in that bicomponent fibers of the side-by-side type are used as latent crimpable fibers, the components of which have different temperatures which trigger the crimping. 3. A method for producing a filler or upholstery material according to claim l, characterized in that thermoplastic fibers with latent twistability are used. 4. A method for producing a filler or upholstery material according to claim 1, characterized in that fibers are used which, due to their molecular structure, are latently curable along a longitudinal edge. 5. A method for producing a filler or upholstery material according to claim 1 to 4, characterized in that mixtures of fibers with different crimping temperature are used. 6. A method for producing a filler or upholstery material according to one of claims 1 to 5, characterized in that the nonwoven fabric consists of 100% latent crimpable fibers. 7. A method for producing a filler or upholstery material according to one of claims 1 to 5, characterized in that the nonwoven fabric contains less than 30% by weight of thermoplastic binding fibers. 8. A method for producing a filler or upholstery material according to one of the preceding claims, characterized in that the nonwoven scrim is needled before the application of the binder. 9. A method for producing a filler or upholstery material according to one of the preceding claims, characterized in that the binder is sprayed onto the fleece on the top and bottom.