WO2007131738A1

WO2007131738A1 - Cuttable and free-flowing natural fiber yarns for smc moulding materials (sheet moulding compounds) and nonwoven strips, method for the production and use thereof

Info

Publication number: WO2007131738A1
Application number: PCT/EP2007/004222
Authority: WO
Inventors: Herbert Costard
Original assignee: Herbert Costard
Priority date: 2006-05-17
Filing date: 2007-05-11
Publication date: 2007-11-22
Also published as: DE102006023060A1

Abstract

A cuttable and free-flowing yarn made from natural fibers or natural fiber/synthetic fiber mixtures for the production of nonwoven strips and fiber semifinished products for the production of fiber composite materials.

Description

Cutting and pourable natural fiber yarns for

SMC (Sheet Molding Compounds) and Schnitzel nonwovens, process for its production and its

use

The invention relates to the production of cutting and pourable natural fiber yarns in order to make them suitable for use in cutting systems (usually wide-cutting machines) in SMC plants or Schnitzel fleece plants.

GW Ehrenstein, Faserverbund-Kunststoffe, Munich 1992, describes the production of SMC: "Before the actual SMC processing, SMC molding compounds are produced on semi-finished products on an SMC impregnation plant from semi-finished material. In a wide-cutting mill, continuous rovings are cut to a length of 20-50 mm and laid down on a support film coated with a resin / filler mixture. The top is then covered with a second carrier film prepared in the same way. After passing through a compaction group, the resulting SMC semifinished product is wound up. After a certain maturing period of 2 to 4 weeks, which serves primarily for thickening by introduced fillers, the SMC can be processed. For this purpose, blanks are cut out of the flat semifinished product, matched in wall thickness and weight to the respective molded part. These blanks are deposited into packages in the crimping tool and pressed. "(Figure 1, Attachment to SMC production) Rovings (endlessly bundled fiber filaments) are now used exclusively as glass fiber rovings, carbon fiber rovings and other synthetic fibers. Due to their smoothness, rigidity, rectilinear alignment and cutting ability, these fibers have the property that they can be deposited or deposited uniformly and unhindered on the carrier film after the cutting process. This is a prerequisite that in the subsequent compression of the SMC mass, the fibers flow evenly with the resin composition.

Similar requirements with regard to the cutting and flowability of the fibers are made, for example, in the production of so-called mats for the production of hand-laminated components (for example in boat construction). The production of the mats thereby takes place on similar machines as with the SMC production. The rovings pass through a cutting unit, trickle and are deposited on a rotating sieve and are generally glued together by spraying an adhesive, usually polyvinyl alcohol or, for example, starch, in order to make the mats manageable. Prerequisite for hand lamination is a mat that can be easily put down in a mold and, above all, that is capable of reeling in order to be able to lay the shape evenly with the fiber fabric before the resin is introduced by brushing and rolling. As with the SMC, glass fiber rovings, carbon fiber rovings and other synthetic fibers are also used here because of the smoothness, rectilinear, unidirectional orientation, flowability and non-crimping and hooking together.

The described rovings are mainly characterized by a unidirectional orientation, which is of central importance for the utilization of the fiber strength in the composite.

Natural fibers, ie in particular cellulose fibers such as cotton, all scleral fibers such as hemp, Flax, nettle and ramie are finite fibers from cells of the corresponding plant. Depending on the preliminary stage of the processing, these can be present as a single fiber or as a fiber bundle. However, all of these fibers have a peculiarity that they are processed in random, curled and not unidirectionally aligned, especially in general when they exceed a certain length. There is a ratio of fiber fineness and length with respect to the unidirectional orientation. Essential for the transmission of force in a composite material is not only the actual fiber strength, but also the fiber length.

DE 102 30 235 A1 describes a wet process for producing a natural fiber fleece, which sets the fiber length to preferably 10 to 25 mm. The process necessitates a separate process for nonwoven production. The fleece is suitable for use in the SMC process and as a so-called Schnitzelvlies for hand lamination.

It is an object of the present invention to provide a novel natural product which is capable of being cut and poured and a process for its production, the product especially having properties which make it suitable to be processed on the above-described SMC and Schnitzel fleece plants can.

The object of the invention is achieved by a cutting and pourable natural fiber yarn, which is characterized in that it is equipped with a binder.

Further, it is achieved by methods for producing such a cutting and pourable natural fiber yarn, which is characterized in that the fibers are processed into a yarn and the yarn is provided after the spinning process with a binder. The natural fibers are / are processed into a yarn. Any textile spinning processes are suitable for yarn formation.

It can be spun in the long-, medium- and short-fiber spinning process as well as in wet, semi-wet and dry-spinning processes.

The yarn count depends on the corresponding application in relation to the finished components. The yarn count is between Nm 3 and Nm 80, preferably between Nm 10 and Nm 40.

The yarns are used either as 100% yarns of a fiber type, ie, for example, of linen fibers, or as blended yarns, for example, a blend of cotton and linen, or viscose and linen, among others. For special applications and special requirements, mixtures with synthetic fibers, for example polyester, are also provided.

A blend of cotton and linen, for example, ideally meets the demands of a composite material due to the impact strength of the cotton and the stiffness of the linen fiber.

The yarn is provided with a binder which makes it smoother and stiffer, and in particular, capable of cutting and pouring.

The yarn / method is characterized in particular by the fact that the yarn after the spinning process for stiffening and weighting to free-flowing with a size, a resin size, with starch or the like, with a water-solidifying agent or with polyvinyl alcohol or epichlorohydrin resin, in particular polyvinyl alcohol or epichlorohydrin resin, impregnated or coated or encased.

The amount of binder applied is in particular between 0.5 and 25%, preferably 10%.

For coating the yarns, it is possible to use the warp tree sizing machines customary in the textile industry or else single or multiple-thread coating installations.

The so-equipped, in particular coated yarns are cut after the dry and free-flowing and preferably unidirectional, so that they can be put on a tape or sieve without entanglement and can be oriented on the tape or sieve by appropriate measures in their orientation.

The yarns thus produced are similar to the rovings made of glass or synthetic fibers on the SMC or Schnitzelvliesanlagen processed and can give a drapible Schnitzelvlies or a flowable SMC semi-finished.

The possible cutting length of the yarns does not differ from the possible cutting lengths of the rovings made of glass or synthetic fibers, so that composites with high strength can be made from natural fibers.

Examples

example 1

An OE yarn Nm 10, 50% cotton / 50% linen was used. The application of a yarn coating was carried out on a coating and thermofixing the Fa. Dietze and P2007 / 004222

Schell, Coburg. As the coating agent, a 10% PVA solution in water at a running speed of 80 m / min was used. This was followed by drying at 160 ^° C.

The yarn was cut to a cut length of 50 mm on an SMC system from Schmidt & Heinzmann, Bruchsal.

The ability to cut, pour and drape as well as the flowability with the polymer corresponded to the requirements.

Example 2

A ring yarn Nm 40, 50% cotton / 50% linen was used. The application of a yarn coating was carried out on a coating and thermofixing the Fa. Dietze and Schell, Coburg. As the coating agent, a 20% PVA solution in water at a running speed of 100 m / min was used. This was followed by drying at 160 ^° C.

The yarn was cut to a cutting length of 50 mm on an SMC plant from Schmidt & Heinzmann, Bruchsal.

Example 3

It was used a ring yarn Nm 34, 100% cotton. The application of a yarn coating was carried out on a coating and thermofixing the Fa. Dietze and Schell, Coburg. As the coating agent, a 20% PVA solution in water at a running speed of 100 m / min was used. This was followed by drying at 160 ^° C. The yarn was cut to a cutting length of 40 mm on an SMC system from Schmidt & Heinzmann, Bruchsal.

The cutting, trickling and draping ability met the requirements.

Fig. 1 shows an SMC plant It. G.W. Ehrenstein, Faserverbund Kunststoffe, Munich 1992.

Claims

claims

1. Cutting and pourable natural fiber yarn, characterized in that it is equipped with a binder.

2. Natural fiber yarn according to claim 1, characterized in that it is impregnated or coated with the binder.

3. Natural fiber yarn according to claim 1 or 2, characterized in that the binder is selected from sizing, resin size, starch, water-hardening agent, polyvinyl alcohol or epichlorohydrin resin, and in particular Polyvinylakohol or epichlorohydrin resin.

4. Natural fiber yarn according to one of the preceding claims, characterized in that the amount of binder, based on the weight of the yarn used, in the range of 0.5 to 25 wt .-%, in particular about 10 wt .-%.

5. Natural fiber yarn according to one of the preceding claims, characterized in that the fibers are cellulosic fibers, in particular cotton, sclerenchyma fibers, in particular hemp, flax, linen, nettle, and ramie, mixtures thereof and mixtures thereof with synthetic fibers, in particular polyester and viscose, acts.

6. Natural fiber yarn according to one of the preceding claims, characterized in that it consists of a fiber type (100%

Yarn) is formed. 04222

7. Natural fiber yarn according to one of the preceding claims, characterized in that it is a mixed yarn of two or more fiber types is formed, in particular of cotton and linen or viscose and linen.

8. Natural fiber yarn according to one of the preceding claims, characterized in that the fibers are present as individual fibers or fiber bundles.

9. Natural fiber yarn according to one of the preceding claims, characterized in that the yarn count is in the range of Nm 3 to Nm 80, preferably Nm 10 to Nm 40.

10. Natural fiber yarn according to one of the preceding claims, characterized in that it is in the form of rovings.

11. Natural fiber yarn according to one of the preceding claims, characterized in that it is cut and several yarn threads are present side by side in unidirectional or free-drizzled in multidirectional form.

12. Natural fiber yarn according to one of the preceding claims, characterized in that a plurality of yarn threads are present side by side or crossed without entanglement with each other.

13. Natural fiber yarn according to one of the preceding claims, characterized in that the yarn threads or yarn fiber sections are present in layers as a fleece.

14. Natural fiber yarn according to one of claims 1 to 12, characterized in that the yarn threads or yarn thread sections are drizzled as a disordered web.

15. Natural fiber yarn according to one of the preceding claims, characterized in that the yarn threads or yarn thread sections are dimmed in the form of a drapable nonwoven fabric.

16. Natural fiber yarn according to one of the preceding claims, characterized in that the yarn threads or yarn thread sections are in the form of a nonwoven doted and with a registered polymer flowable and drapierfähig.

17. Natural fiber yarn according to one of the preceding claims, characterized in that the yarn threads or yarn thread sections are glued together.

18. A method for producing a cutting and pourable natural fiber yarn, characterized in that the fibers are processed into a yarn and the yarn is equipped after the spinning process with a binder.

19. The method according to claim 18, characterized in that the natural fiber yarn is impregnated or coated with the binder.

20. The method according to claim 18 or 19, characterized in that the binder is selected from sizing, resin size, starch, water-solidification agent, polyvinyl alcohol or epichlorohydrin resin and in particular polyvinyl alcohol or epichlorohydrin resin.

21. The method according to any one of claims 18 to 20, characterized in that the amount of binder, based on the weight of the yarn used, in the range of 0.5 to 25 wt .-%, in particular about 10 wt .-% ,

22. The method according to any one of claims 18 to 21, characterized in that the fibers are cellulose fibers, in particular cotton, sclerenchyma fibers, in particular hemp, flax, linen, nettle, and ramie, mixtures thereof and mixtures thereof with synthetic fibers, especially polyester and viscose, is.

23. The method according to any one of claims 18 to 22, characterized in that the yarn of a fiber type (100% yarn) is formed.

24. The method according to any one of claims 18 to 23, characterized in that the yarn is a composite yarn of two or more fiber types is formed, in particular of cotton and linen or viscose and linen.

25. The method according to any one of claims 18 to 24, characterized in that the fibers are used as individual fibers or fiber bundles.

26. The method according to any one of claims 18 to 25, characterized in that a yarn with a yarn count in the range of Nm 3 to Nm 80, preferably Nm 10 to Nm 40 is used.

27. The method according to any one of claims 18 to 26, characterized in that a yarn is used in From rovings.

28. The method according to any one of claims 18 to 27, characterized in that the yarn is cut and a plurality of yarn threads are present side by side in unidirectional or free-drizzled in multidirectional form.

29. The method according to any one of claims 18 to 28, characterized in that a plurality of adjacent yarn threads, in particular rovings are cut.

30. The method according to any one of claims 18 to 29, characterized in that after the cutting operation, the yarn sections are placed in a unidirectional form on a belt or wire in layers as a fleece, with no entanglement of the yarn sections takes place with each other.

31. The method according to any one of claims 18 to 30, characterized in that after the cutting process stored on a belt or wire yarn sections are placed in the desired direction and moved without getting caught.

32. The method according to any one of claims 18 to 31, characterized in that with the cut and sprinkled yarn sections a drapable nonwoven fabric is formed.

33. The method according to any one of claims 18 to 32, characterized in that with the cut and sprinkled yarn sections, a non-woven is formed, which is flowable and drapierfähig with a registered polymer.

34. The method according to any one of claims 18 to 33, characterized in that the deposited on a sieve as a non-woven yarn sections are easily glued together.

35. Use of a natural fiber yarn according to one of claims 1 to 17 for the production of Schnitzel fleeces and semi-finished fiber products for the production of fiber composites.