PT2181216E - Method for producing a ductile, elastic non-woven fabric based on polyester fiber - Google Patents

Abstract

The invention relates to a method for producing a ductile, elastic non-woven fabric based on polyester fiber and having a high-shrinkage material component, the fiber mixture being in solution and laid out in a carding engine to form the fabric, said fabric having transverse and longitudinal connection of fibers, the polyester fibers being subsequently fixed. According to the invention, the solidified fabric is fed quickly through a tensioning frame with slack, and there exposed to a further or additional temperature treatment, in order to initiate the shrinking process of the high-shrinkage material component, resulting in loss of surface area and crinkling of the non-woven fabric, so that the desired elasticity is obtained in the material in both the longitudinal and transverse directions.

Description

The invention relates to a process for the production of an elastic non-woven fabric based on polyester fibers and quot; The invention relates to a process for the production of an elastic non-woven fabric based on polyester fibers having a high shrinkage ratio, in which it is in a disaggregated form and in a carding machine that the fiber blend is transformed in non-woven fabric, which exhibits a transverse and longitudinal bonding of the fibers to each other, after which the thermal bonding of the polyester fibers is carried out, in accordance with the generic concept of claim 1.

Non-woven fabrics are two-dimensional formations composed of individual fibers that require consolidation to ensure processability. The nonwoven is distinguished by the type and origin of the fibers. Thus, fibers of animal origin may be used, but also chemical fibers. The use of polyester fibers, namely polyethylene or polybutyl te-reftalates, is popular.

Nonwovens are also used as garments in the textile industry. In DE 10 2005 057 221 AI is given as non-woven a two-dimensional formation 2 ΡΕ2181216 special fixable textile. Accordingly, the two-dimensional textile securable formation includes a nonwoven, woven, crocheted or knitted base support, one side of this two-dimensional formation having been coated with an adhesive mass. On the adhesive coating was applied at least one additional layer composed of fibers having a predefined functionality. This additional layer is intended to give the two-dimensional formation a high elasticity.

EP 0 317 646 AI discloses a process for the production of an elastic nonwoven extensible based on polyester fibers having a high shrinkage ratio. It was intended to produce a non-woven fabric in which the requirement for the strain coefficient was low and exhibited sufficient additional tensile strength. In addition, the material obtained should have an exceptional dyeability. The production process described in EP 0 317 646 A1 relates to the use of two component fibers which must be present in the nonwoven in a percentage of not less than 30% by weight, a heat treatment having to be carried out provided that there are sufficient elasticity, either in the longitudinal direction or in the transverse direction.

In EP 0 317 646 A1 is described as the central step being a heat treatment in the form of 3 ΡΕ2181216 irradiation with very large wavelength infrared. Specifically, it is shown in this document that a product having a very high unit tension coefficient in both directions can be produced by a single process in which a region of the heat-treated raw material undergoes a shrinkage in the directions both longitudinal and transverse. The shrinkability of the materials used can be counteracted by the application of steam.

EP 0 815 305 B1 discloses a nonwoven of thermoplastic fibers designed to be used for disposable articles, such as, for example, surgical gowns and disposable garments.

The composite fibers used therein include a higher melting polymer component as well as a lower melting polymer component wherein, in the bound textile material, the higher melting polymer component involves the melting point polymer component having a lower melting point, thereby forming the outer upper surface extending along the length of the fibers, whereby a core-shell arrangement is obtained. This non-woven textile material obtained from such composite fibers is supposed to have a greater softness, improved tactile properties, a greater wrapping capacity and finally a greater resistance to wear. 4 ΡΕ2181216

In EP 0 815 305 B1 there were further disclosed wrinkled composite fibers. Such composite fibers contain at least two polymeric components spanning distinct cross-sections of the fibers. For this purpose polymers with distinct retraction properties may be used. Irrespective of the difference in shrinkage between the polymeric components contained in the fibers during or after the spinning process of the fibers, wrinkling may occur. If it is composed solely of composite fibers, a nonwoven actually has its increased bonding capacity, but its wear resistance is relatively less and the elastic properties are insufficient.

It has been found that the invention underlies the task of indicating an improved process for the production of an elastic non-woven fabric based on polyester fibers having a high shrinkage ratio, which process would result in a nonwoven having an adequate elasticity, either in the longitudinal direction or in the transverse direction. It was further envisaged that the nonwoven would have such a pronounced engagement capacity that non-woven layers that were subject to an overlap would remain adherent in the absence of external intervention. The object of the invention has been achieved by a process according to claim 1, the dependent claims representing the preferred and preferred embodiments being advantageous.

According to the invention, it is based on a process known per se for the production of thermal nonwoven. Polyester fibers containing a high shrinkage ratio are used in this process. Composite fibers are in particular used which exhibit a retractable behavior characterized by a zone of minor and a zone of greater retraction, each corresponding to a different retraction temperature. The fiber blend is disintegrated and transformed into the nonwoven in a carding machine so as to provide a transverse and longitudinal connection between the fibers, after which the thermofixation of the polyester fibers is effected. The fixing of the polyester fibers is carried out by a heat treatment at a typical temperature with respect to polyester fibers. The consolidated nonwoven is then to produce an excess of material that can reach 50%, leading in advance and lassitude to a tensioning frame, where it is either new or additionally subjected to a heat treatment in order to trigger the retraction of the proportion of highly shrinkable material. As a result of this further heat treatment there is a loss of area and a wrinkling of the nonwoven, from which the desired elasticity for the material, either in the longitudinal direction or in the transverse direction, results. The temperature at which the treatment is carried out to trigger the retracting process of the highly shrink material is higher than the temperature of the thermal fixture used in the first consolidation treatment step. The residence time of the non-woven fabric in the heat setting process is restricted to a time interval which excludes the triggering of the retraction process.

Preferably, the fiber web removed from the carding machine is compressed and collected in its predominant longitudinal direction by means of misaligning cylinders, so that a transverse and longitudinal connection of the fibers in the nonwoven is achieved. The desired transverse and longitudinal connection between the fibers is thus achieved, which promotes the desired longitudinal and transverse elasticity of the final product. Thermal fixation can be done using a heated calender.

From the advance in the tensioning frame results an excess of material that can reach 50%. In other words, it is in a relatively unfixed state that the material is conveyed through the tensioning frame. Once the chosen temperature exceeds the temperature range capable of triggering the retracting process of the highly shrinkable fibers, the desired shrinkage and shrinkage process occurs and the area of the material decreases. This area represents the maximum posterior elasticity up to which the material is reversibly stretched.

The fibers used consist of two components, of which the former exhibits regular shrinkage properties, while the latter exhibits a shrinkage behavior at higher temperatures.

Fibers of this type are known in the present state of the art. By way of example, reference is made here to the descriptions in US 5,545,464 or US 6,982,118.

According to these documents, the fibers consist of composite fibers in which the components comprise distinct cross-sections thereof. A distribution of the components with distinct shrinkage properties corresponds to approximately 50:50. A deliberate wrinkling of the non-woven strip in the course of the heat treatment is inseparable from the abrupt lifting of the ends of the fibers, whereby the outer surface of the strip of material acquires the ability to engage.

In a further treatment step, the obtained elastic and extensible nonwoven may be subjected to a punctate dressing with a thermally active adhesive material for the purpose of its subsequent attachment to an outer fabric. The invention will now be described in more detail with reference to an exemplary embodiment.

According to the exemplary embodiment, the fibers used consist of a percentage which may amount to up to 100% of a blend of polyester fibers (PES) containing a highly retractable fraction of polyester fibers.

In this case, composite fibers produced by Unitika Ltd. were used, in particular type 82, but in combination with standard PES fibers. The type 82 fibers are comprised of a conventional polyethylene terephthalate component and a further polyethylene terephthalate component exhibiting strong temperature dependent retraction properties. These two components have been associated in a composite fiber, being equally distributed therein, for example, to the cross-section thereof.

It starts by producing a classic thermal non-woven fabric in which the fraction of highly retractable PES fibers is not caused to retract or only minimally, which is achieved by a suitable adjustment of the parameters of the machines involved. 9 ΡΕ2181216 The fibrous mixture is pre-separated within an opening path and then fed to the carding machine by means of a feed device. The carding machine separates the fibrous material into the individual fiber. Thereafter, the fibrous aliquot is compacted by means of a withdrawal cylinder and again collected by the drum. The longitudinal orientation in force in the material and resulting from the separation of the fibrous mass realized in the previous step is partially collected using disorienting cylinders, so as to establish transverse and longitudinal connections of the fibers between them, which reinforces the desired effect of an elasticity longitudinal and transverse. The fiber web thus obtained is consolidated using a calender heated to a temperature typical for polyester fibers, in which process, because the length of stay of the fiber web in the hot zone is relatively short, the retraction process of the strongly retractable material is not unchained or, if so, gives rise to minimal shrinkage. The retracting process of the highly retractable material is triggered in a tensioner frame. The material is driven through a tensioning frame with advancement and in a relatively unfixed state, 10 ΡΕ2181216 i.e., lassitude. As a consequence of the chosen temperature which is in the range of temperatures capable of triggering the retraction process of the highly shrinkable fibers, the retraction process takes place. In this process the material strip wrinkles and the area of its surface decreases. This loss of surface subsequently determines the degree of elasticity with which the material stretches back. The highly elastic nonwoven according to the longitudinal and transverse directions thus obtained may, if necessary, be coated and provided with an adhesive material, which is destined for a subsequent bonding of the nonwoven with an upper outer fabric. The abrupt lifting of the ends of the fibers during the retraction process is responsible for acquiring the non-woven engaging capacity.

The engaging properties result from lifting the ends of the fibers in an upward direction relative to the plane of the strip of material, which ends together may form a formally complementary union with the fibers or fiber ends exhibited by a non-woven strip -texture that is subsequently superimposed on the first strip.

In an elastic stretch test performed with a nonwoven sample according to the invention in the original state 11 ΡΕ2181216 a surface weight of between 28 and 30 g / m 2 was determined for a mean thickness of 0.75 mm.

After the heat treatment in the retracting step of the highly shrinkable material, a surface weight of approximately 48g / m2 was obtained for a thickness of 0.75mm.

A maximum elastic stretch in the longitudinal direction is achieved for 10-40% of the maximum force applied and in the transverse direction for 8-45% of the maximum permitted force application, with full reversibility. The values for a preferred embodiment correspond to 14% of the maximum permitted force application and, in the transverse direction, 10% of the maximum force applied.

Lisbon, June 25, 2012

Claims (9)

A process for the production of an elastic non-woven fabric based on polyester fibers having a proportion of highly shrinkable material, in which it is in a disaggregated form and in a carding machine that the fiber blend is transformed into the non-woven fabric. which shows a transverse and longitudinal connection of the fibers to one another, after which the polyester fibers are fixed, characterized in that, in order to produce an excess of material which may reach 50%, the nonwoven to be conveyed with advancement and lassitude to a tensioning frame where it is either new or additionally subjected to a heat treatment in order to trigger retraction of the proportion of highly shrinkable material, which results in a loss of area on its surface and a wrinkling of the nonwoven from which the desired elasticity for the material results either in the longitudinal direction or in the direction transverse direction where, as a consequence of the wrinkling, a lifting of the ends of the fibers which confers the ability to engage the non-woven strip surface occurs, in addition, in addition, by the residence time of the non-woven in the fixing step thermal bonding is restricted to a time interval which totally or totally excludes the triggering of the retracting process of the highly shrinkable material. Method according to claim 1, characterized in that the fixing of the polyester fibers consists of a thermal setting carried out at a treatment temperature typical of polyester fibers. Method according to one of the preceding claims, characterized in that the fiber web removed from the carding machine is compressed and collected according to its predominant longitudinal direction by means of disorienting cylinders, so as to achieve a transverse and longitudinal connection of the fibers in the non-woven. Method according to one of Claims 1 to 3, characterized in that the thermal fastening is carried out using a heated calender. Process according to one of the preceding claims, characterized in that a part of the fibers used consists of fibers consisting of two components, of which the former exhibits regular retraction properties, while the latter exhibits a retraction behavior at higher temperatures high Process according to claim 5, characterized in that the fibers consist of composite fibers. Process according to claim 5 or 6, characterized in that the components cover different cross-sections 3 ΡΕ2181216 of the fibers A process according to claim 7, characterized in that a distribution of the components approximately corresponding to 50:50 is chosen. Process according to one of the preceding claims, characterized in that the obtained nonwoven is subjected to a punctate coating with an adhesive material for the purpose of its subsequent fixing on an outer fabric. Lisbon, June 25, 2012 1 ΡΕ2181216 REFERENCES CITED IN DESCRIPTION This list of references cited by the applicant is for the reader's convenience only. It is not part of the European patent document. While due care has been taken in compiling references, errors or omissions may not be excluded and the IEP declines any liability in this regard. Patent documents cited in the specification ♦ DE 102005057221 A1 · US 5545464 A ♦ EP 0317646 A1 · US 6982118 B ♦ EP 0815305 B1