KR19990067624A - Spun yarn of covered high modulus material and fabrics formed therefrom - Google Patents

Abstract

The present invention is directed towards yarns of covered high modulus filament materials and fabrics which are formed therefrom. The present invention is intended to provide a composite filamentary material which exhibits the advantages of high modulus materials while providing a means for compensating the diminished properties exhibited by such fibers in the direction normal to molecular chain orientation. The composite filament structure of the present invention is a high modulus filament material covered with bicomponent filaments. The composite filament structure has a first interior layer of high modulus filament material and a second exterior layer of bicomponent fibers, the second exterior layer of bicomponent fibers being covered around the first interior layer of high modulus material along its entire length. The entire surface area of the high modulus material should be covered.

Description

Spun yarn of covered high modulus material and fabrics formed therefrom

Technical Field of the Invention

The present invention relates to a spun yarn of high modulus material, such as a polymeric material covered in a second material. This yarn can be used to make fabrics and other industrial fabrics used for papermaking clothing.

Papermaking clothing means an industrial fabric used for papermaking in molding, pressing and drying parts. It is generally made of polyester or polyamide multifilament yarns and / or monofilament yarns woven using conventional large-scale textile looms. Such fabrics have generally been made by conventional weaving techniques.

The most important function of all Paper Machine Clothing (PMC) is the removal of water from the paper sheet. Research efforts to increase paper processing speed and improve paper quality for papermakers and papermakers face new barriers that require innovation in materials and fabric construction for PMC fabrics. PMC manufacturers are also looking for ways to make PMC fabrics more efficient and are investigating ways to improve basic quality characteristics.

Currently, paper machines are capable of speeds such that the thickness of the fabric structure, especially in the forming section, begins to limit the rate of water removal. Insufficient dehydration results in low sheet strength. Sheet strength is important for the sheet properties to be transferred and maintained through a more aggressive sheet dewatering step. One possible way is to extend the forming part of the paper machine. However, because this method is more expensive, the feasibility is limited. Another way is for PMC manufacturers to produce thinner fabrics, where the smallest dimension possible in the weaving process is the sum of the diameters of the filament yarns used in the warp and finish directions. Properties such as dimensional stability, fabric strength and fabric life impose substantial limits on the fineness of the filament yarn diameter and thus affect the total thickness of the fabric. For many PMCs, tradeoffs in these properties are either impractical or non-realistic, and in reality faster paper speeds will require even greater improvements in these properties.

There is a need for a thinner, lower weight, thinner cloth of higher strength than is currently available.

The surface shape of PMC fabrics determines the quality of the paper product. Efforts have been made to provide a smoother contact surface for the paper sheet. However, the smoothness of the surface of PMC woven fabrics is limited by the shape resulting from the woven pattern and the physical properties of the filament yarns. In the case of woven fabrics (or knitted fabrics) the smoothness is limited by knukles formed at the intersections of the intersecting yarns.

High modulus materials are potential materials for use in applications requiring high mechanical properties and low weight. Mechanical Properties-Based on weight, high modulus polymers have distinct advantages over metals and ceramics.

High modulus polymers have a highly anisotropic structure, and high modulus is achieved only in the direction towards the molecular chain. In practice, the properties in the direction perpendicular to the molecular axis are significantly lower than those in the axial direction. As a result, low shear and compression properties appear in the direction perpendicular to the molecular axis.

Complex constructions to compensate for discrepancies in properties are known in the art. The representative is US Patent No. 4, as 927 698, here has the yarn refractory filament yarn cores, such as Kevlar ^ⓡ and Nomex ^ⓡ is disclosed in a shrinkable synthetic fiber sheath, the yarn is first on the refractory core through the reactions between a first cross-linkable resin 2 Cross-linkable resin, Kevlar ^® / Nomex ^® components and artificial fiber components are chemically bonded.

1 is a composite braid fabric of the present invention.

2 is another composite braid fabric of the present invention.

3 is a cross-sectional view of the yarn of the present invention.

The present invention relates to a spun yarn of covered high modulus filament material and a fabric formed therefrom. The present invention seeks to provide a composite filament material having the advantages of a high modulus material and at the same time having a means for compensating for the reduction properties exhibited by the fabric in a direction perpendicular to the molecular chain.

The present invention has a composite filament structure in which a high modulus filament material is covered with a bicomponent filament. This composite filament structure consists of a first inner layer of high modulus filament material and a second outer layer of bicomponent fiber, with a second outer layer of bicomponent fiber along its length around the first inner layer of high modulus material I cover it. The entire surface area of the high modulus material is covered.

The bicomponent fibers of the present invention may have a sheath-core structure and may have side-by-side structures, but a sheath-core structure is preferred. It is also desirable that the sheath component has a lower melting point than the core component.

Suitable bicomponent fibers include copolyester / poly (ethylene terephthalate), polyamide / poly (ethylene terephthalate), polyamide / polyamide, polyethylene / poly (ethylene terephthalate), polyethylene / polyamide, polypropylene / Exterior-core blends such as polyamides, thermoplastic polyurethanes / polyamides and thermoplastic polyurethanes / poly (ethyleneterephthalates).

As used herein, "modulus" means the tensile modulus defined by the slope of the initial linear portion of the load elongation response (stress strain curve) of the sample material deformed at room temperature.

High modulus materials as used herein include high modulus polymers exhibiting tensile modulus higher than about 25% of theory. High modulus polymers also include polymers with tensile modulus higher than about 25 GPA ( Encyclopedia of Polymer.Science 2nd ed. Vol 7. pp. 699-722). It should be noted here that the polymer structure that is highly oriented toward a certain direction is anisotropic, and the coefficient increases as the degree of molecular chain direction increases, so that in other directions, the coefficient decreases proportionally.

Suitable high modulus polymers include DuPont (Dupont) can purchase the trade name Kevlar ^ⓡ captured from poly (p- phenylene terephthalamide), available from the purchase of aramid, Rhone-Poulenc and captured and Kermel ^ⓡ, Akzo, available from captured Arenka ^ⓡ , Dupont, available another aramid, polyethylene naphthalate (PEN) such as Nomex ^ⓡ, captured from poly (p- phenylene-benzo Beastie azole), polyesters, glass, aromatic polyamide resin Arenka ^ⓡ (commercially available from Akzo aramid captive ), Fibrous copolyesters such as Vectra ^® (Celanese) and Xydar ^® (Dart), high modulus polyethylene fibers such as Spectra 900 (Allied), and the like.

Those skilled in the art will recognize that there are many ways in which high modulus internals can be covered, such as braiding and wrapping. By braiding the bicomponent fibers around the high modulus internal material, a structure having excellent stability is provided. Wrapping high modulus internal fibers with bicomponent fiber materials is another suitable method. The fibers may be covered by a single covering device or a double covering device. In this case the core fibers may be spirally covered at a selected pitch.

In producing the fabric of the present invention, the advantage is that it has a unique structure of bicomponent filament yarns. The melting point of the sheath component is lower than the melting point of the core component and lower than the melting point of the high modulus internal material. Improved structural integrity is imparted by heating and then cooling a fabric formed from yarns that cross each other in the fabric to a temperature above the melting point of the sheath but below the melting point of the core and high modulus internals. This process (hereinafter referred to as heat melting) causes the sheath component of the bicomponent fiber to enter a softened state, causing the yarn to melt together at the point of contact when cooled to a temperature below the melting point of the sheath material. In most cases, this point of contact is where the yarns intersect each other.

Because of the improved stability of the fabric of the invention, single layer fabrics woven from the composite spun yarn of the invention can be successfully operated on paper machines. That is, the present invention provides a means for making a single layer fabric that can withstand the operating conditions subjected to papermaking clothing. In general, the fabric should be made of at least two layers to have the dimensional stability and strength necessary to withstand the required operating conditions.

The present invention can also be used as a top laminated structure of a multi-layer structure, which uses as a layer provides advantages over conventional conventional materials due to the reduction in knuckle size and the thickness of the fabric on the surface of the fabric. The reduced knuckle size results in a smoother fabric surface and has the desired shape by the papermaker. The superior tensile properties of high modulus materials also mean that fewer materials are used to achieve the strength levels typically found by conventional fabrics, making thinner fabrics using the high modulus composite spun yarn of the present invention. It is possible to do The present invention can also be used as a base layer for multilayer structures. The improved dimensional stability of this layer makes it very suitable for use. By using the fabric according to the invention as the base layer, it gives an advantage to the overall fabric production. Since the composite spun yarn of the present invention exhibits a relatively high level of strength along the axis of the spun yarn, the use of the present fabric layer as a base layer can provide the stability and strength required for the overall fabric structure. Thus, less rigid materials can be used for other fabric layers, for example, allowing a papermaker to select fine denier fibers to make another layer. Thus, the fabric can also be made thinner in this way. Thin fabrics are preferred because of their improved drainage properties.

In a preferred embodiment of the invention, the yarn of the invention is the only component that constitutes at least one layer of clothing. In the case of multi-layer cladding, at least one layer consists of the yarns of the invention and preferably constitutes the surface layer in contact with the paper sheet. Whether the fabric is a single layer or a multilayer, the bicomponent fibers are arranged in an orderly fashion. This orderly arrangement means: In other words, the fibers of the clothing are operated in the first direction, and the first direction fibers do not intersect the other fibers operated in the first direction. The fibers of the clothing also operate in a second direction, and the second direction fibers do not intersect with other fibers operated in the second direction. The fibers acting in the first direction intersect with the fibers acting in the second direction and vice versa. For example, the fibers arranged in the machine direction do not intersect each other, only the fibers operated perpendicular to the machine direction. The clothing of the present invention is preferably composed of fibers operated in the machine direction or in a direction perpendicular to the machine, but may be composed of fibers operated in an oblique direction with respect to the machine direction of the paper machine and the direction perpendicular thereto.

1 is a fabric made of the yarn of the present invention. This fabric is a knitted weave woven in the warp and weft directions with the spun yarn of the present invention. From Figure 1, it can be observed that the yarns are interconnected with other yarns at the point where the yarns intersect. This is due to the thermal melting of the yarn of the yarn, whereby the two-component material sheaths are fused to each other by heating the fabric to a temperature higher than the melting point of the two-component sheathing material and below the melting point of the core material.

The warp and weft of the fabric shown in Figure 1 have the same structure. The high modulus internals of the yarn are Kevlar ^® 49, which is about 134 filament yarns. Eight bicomponent spun yarns are braided around this Kevlar ^® inner material. Each yarn consists of 16 bicomponent filament yarns. And a living filament Kanebo's Bellcouple ^ⓡ, 250 deniers, and a filament number of 16, and having a low melt copolyester sheath material and a poly (ethylene terephthalate) core, wherein the melting point of the copolyester sheath material is lower than the melting point of the PET core .

Eight bicomponent yarns are braided around the Kevlar ^® inner material. Braiding (twisting) forms a relatively stable structure, and the covered high modulus yarns can be used to make fabrics as shown in FIG. Such fabrics are made according to methods well known in the art. After fabrication, the fabric is placed under tension, heated to a temperature above the melting point of the sheath material and below the melting point of the core, and then cooled to a temperature below the melting point of the sheath material.

Due to the improved stability of the fabric of the present invention, single layer fabrics woven with the composite spun yarn of the present invention will be able to operate successfully on paper machines. That is, the present invention provides a means of making a single layer fabric that can withstand the operating conditions subjected to papermaking clothing.

In general, the fabric consists of at least two layers to have the dimensional stability and strength necessary to withstand the required operating conditions well. However, since the papermaking cladding of the present invention is characterized by high modulus, low stretch material, the strength and dimensional stability of the fabric is provided by the high modulus material layer, thus single layer fabrics are also possible. In other words, due to the high strength provided by the materials of the present invention, it is not possible to use less material while giving much higher or the same strength as compared to a multilayer material containing significantly more material for weaving fabrics. It is possible. Achieving single layer fabric constructions is a breakthrough in PMC construction. As the machine speed increases, the drainage time is shortened, the possibility of achieving the smallest possible thickness is greater, and the single-layer fabric is thinner than the multi-layer fabric, which shortens the distance the liquid must penetrate for drainage. .

The present invention can also be used as a top stacked structure of a multi-layered structure, which when used as such a layer provides an advantage over conventional materials as the flatness on the surface is increased. The improvement in flatness is a result of the reduced knuckle size at the point where the yarn crosses. Upon thermal melting of the fabric, the low melt component of the bicomponent fiber collapses and flows, reducing the knuckle size at the intersection.

The invention can also be used as the base layer of a multilayer structure. The improved dimensional stability of this layer can make it very suitable for its use. Since stability and strength are imparted by a layer of high modulus material, other materials, such as materials with fine diameters, may be used for the other layers. By using a material having a fine diameter for the paper sheet contact layer, the smoothness of the surface can be improved, and the shape of the paper machine cladding can be made desirable.

FIG. 2 illustrates a fabric in which the yarns described in FIG. 1 are used in an inclined direction. The yarn in the weft direction consists of 9 strands of material. That is, it is nine strands of spun yarn made of a bicomponent material as described in FIG. These yarns are twisted loosely together. This yarn has a distinctly flat appearance. In other words, after thermal melting, the spun yarn has a ribbon-like appearance.

3 shows a cross section of a composite spun yarn according to the invention. The Kevlar ^ⓡ internals are observed as distinct parts. The binary externals are not separated.

In paper machine operation, the fabric according to the invention is kept cleaner than the cladding of conventional conventional monofilament yarns. The thermal melting of fabrics composed of bicomponent fibers is partially characterized by fused cross-spun yarns. In contrast, conventional monofilament yarns have gaps at the points where the yarns intersect. Melting at the intersection of the bicomponent fibers minimizes these gaps and can be eliminated completely. A gap is a pinch that can cause fragments to become trapped and cause overtime. Thus, the hot melt cross spun yarn composed of bicomponent fibers provides a structure that is kept relatively clean than the cladding made of conventional monofilament yarns.

Another advantage of the papermaking cladding according to the present invention over the cladding of conventional monofilament yarns is that the cladding has a relatively flat, knuckle free surface at the point of intersection. When the fabric is woven or woven, it is easy to see that knuckles are formed that reduce the smoothness of the surface. It should be noted that by kneading the bicomponent fibers, the knuckle size is reduced, thus improving the smoothness of the surface. Surface smoothness is a factor in paper quality. Therefore, smoothing improved cladding is of great interest to manufacturers of paper and related products. The bonding network between the intersecting fibers is formed upon thermal melting of the cladding consisting of the bicomponent fibers. This kind of physical bonding improves dimensional stability compared to cladding made of conventional monofilament yarns. Due to the nature of the bicomponent fiber and the unique structure it forms, it is possible to use fibers of denier lower than required when using conventional monofilament yarns. The use of low denier fibers provides the advantage that thinner cladding is possible over the cladding of conventional monofilament yarns without sacrificing fabric strength.

Claims (18)

A composite spun yarn composed of a first high modulus filament yarn material and at least one second filament yarn material, The first high modulus filament yarn material is covered in a second material, The composite yarn, The first high modulus filament yarn material, A second bicomponent filament yarn material having an exterior component and a core component, covering a circumference of the first high modulus filament yarn material, and enclosing the first high modulus material along the length of the composite spun yarn; Composite spun yarn, characterized in that. The method of claim 1, The first high modulus material is a high modulus polyamide, aramid, poly (ethylene naphthalate), glass fiber, pyrogenic aromatic copolyester, poly (p-phenylenebenzobisthiazole), polyester, high modulus polyethylene fiber Composite spun yarn, characterized in that selected from the group consisting of. The method of claim 1, The sheath-core blend of bicomponent fibers is copolyester / poly (ethylene terephthalate), polyamide / poly (ethylene terephthalate), polyamide / polyamide, polyethylene / poly (ethylene terephthalate), polyethylene / polyamide , Polypropylene / polyamide, thermoplastic polyurethane / polyamide and thermoplastic polyurethane / poly (ethylene terephthalate). The method of claim 1, The first spun yarn layer further comprises a plurality of high modulus filament yarns. The method of claim 1, The second outer spun yarn layer further comprises a plurality of bicomponent yarns, wherein each bicomponent layer is also comprised of bicomponent filament yarns having a sheath-core arrangement. In the fabric for use in the forming, pressing or drying of the paper machine, The fabric has one or more layers, The at least one layer comprises a composite spun yarn made of a high modulus material and at least one second material, The high modulus filament yarn material is covered in a second material, Said composite spun yarn comprising a first internal spun yarn layer of high modulus filament yarn material, It consists of a second spun yarn layer of bicomponent filament yarn material of core and sheath components, And said bicomponent filament yarn material covers a circumference of said first high modulus filament yarn material and wraps said first high modulus material along the length of said composite spun yarn. The method of claim 6, The fabric consisting of the yarn is woven. The method of claim 6, The fabric consisting of the yarn is woven. The method of claim 6, The composite yarns weaving characterized in that it is developed in a warp direction with the weft yarns. The method of claim 6, The composite spun yarn is characterized in that it is deployed in an oblique direction. The method of claim 6, The composite spun yarn is characterized in that it is deployed in the weft direction. The method of claim 6, The first high modulus material is a high modulus polyamide, aramid, poly (ethylene naphthalate), glass fiber, pyrogenic aromatic copolyester, poly (p-phenylenebenzobisthiazole), polyester, high modulus polyethylene fiber Woven fabric, characterized in that selected from the group consisting of. The method of claim 6, The sheath-core blend of bicomponent fibers is copolyester / poly (ethylene terephthalate), polyamide / poly (ethylene terephthalate), polyamide / polyamide, polyethylene / poly (ethylene terephthalate), polyethylene / polyamide , Polypropylene / polyamide, thermoplastic polyurethane / polyamide and thermoplastic polyurethane / poly (ethylene terephthalate). The method of claim 6, Fabric comprising a plurality of high modulus filament yarns. The method of claim 6, The second outer spun yarn layer further comprises a plurality of bicomponent spun yarns, each bicomponent layer also consisting of bicomponent filament yarns having a sheath-core arrangement. The method of claim 6, The fabric is characterized in that the fabric is heated to a temperature above the melting point of the sheath component and above the melting point of the core component and then cooled to a temperature below the melting point of the sheath component. The method of claim 6, A composite spun yarn is characterized in that it is thermally melted prior to the formation of the fabric. The method of claim 6, The fabric is characterized in that the single layer fabric.