JPH04240256A - Fiber material for deep draw formation and shaped article produced therefrom - Google Patents

Abstract

PURPOSE: To obtain a non-woven fabric which is used for deep drawing, exhibits highly stable dimensional stability in an impregnation process, can be drawn in a sufficiently large deep drawing ratio, and has an isotropic property. CONSTITUTION: This deep-drawnable non-woven fabric is produced as a filament non-woven fabric, contains at least 30 wt.% of filaments having a low orientation degree and a rough fineness, has only mechanically been adhered, and has an isotropic property. The orientation degree of the filaments having the low orientation degree and the rough fineness is at least 80% based on the ultimate tensile strength elongation. Similarly, a resin-treated sheet-like prepreg produced from the non-woven fabric, a three-dimensional textile structure produced from the textile non-woven fabric which is useful for deep drawing and has been treated or not treated with a resin, a sandwiched material having the core of the three-dimensional resin-treated fiber structure, and the method for producing the articles.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to nonwoven fabrics for deep drawing,
A resin-treated sheet-like prepreg produced therefrom, a three-dimensionally printed fiber structure produced using a resin-treated or non-resin-treated deep-drawing nonwoven fabric, and a three-dimensionally printed resin-treated fiber The present invention relates to a sandwich material having a core made from a structure. The invention further relates to a method for manufacturing the above article.

0002

[Prior Art] European Patent Application No. 247 232 discloses that the elongation at break exceeds 100% and the
A nonwoven fabric consisting of filaments with a low degree of preorientation with a birefringence index of 0.07 is described. These nonwovens are thermally preconsolidated with filaments by hot embossing rolls, humidified, and then heat set under tension. This results in adhesive areas and limits the mobility of the filaments within the nonwoven. Subsequent curing under tension creates anisotropy in the thermomechanical properties, which significantly impairs the formability of these nonwovens, at least in the direction of tension.

German Patent Application No. 3 029 752
In the specification, at least one drawing fiber having an elongation at break of at least 100% at a temperature 150° C. below the melting point is included.
In a method for producing a deep-drawn article from a staple fiber web containing 0% by weight, a method is described in which the article is bonded by needling and then deep-drawn at a temperature between 150° C. and the melting point of the drawing fiber. ing. The web can be further reinforced with thermoplastic or thermoset binders. The staple fibers used in this material consist of a very wide range of synthetic polymers, for example with staple lengths of about 50-80 mm and individual filament finenesses of 1.5-20. The shaped articles produced are suitable for use as free-standing filters. However, since only staple fibers are used,
Such filters lack mechanical strength. There is no suggestion in the above specification that the deep draw web may also be composed of continuous fibers; rather, those skilled in the art will appreciate that the deep drawability of this known web is such that it slides relatively easily over each other during deep drawing. This is probably due to the use of short fibers that can be used.

A moldable spunbond web consisting only of partially oriented continuous synthetic fibers is disclosed in German Patent No. 1 560.
No. 797. The fibrous material of these webs consists of polyamide, polyester or polyolefin. To bond the filaments that make up this web, it is compressed in a pattern and impregnated with a binder. The binder concentration varies locally. According to the specification, this particular form of adhesion is critical to the formability of the web. However, as in the case of spot bonding as carried out in EP-A-247 232, here too an anisotropy occurs in the mobility of the filaments within the non-woven fabrics, which leads to Three-dimensional formability is significantly impaired.

It is known from EP 250 005 to produce three-dimensional structures from woven fabrics and ordinary webs by deep drawing. According to this specification, the surface area increased in the deep drawing method is
It is based solely on the inherent stretchability of the sheet material. Therefore, the increase in surface area is small.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to exhibit very good dimensional stability under normal processing conditions, in particular during the impregnation process, and at the same time to be sufficient for all practical purposes. To provide an isotropic nonwoven fabric that is easy to deep draw and which enables a large deep drawing ratio.

[0007]

[Means for solving the problem] In order to solve the above problem,
The isotropic deep drawable nonwoven fabric according to the present invention has a 7 d
The filament nonwoven fabric contains at least 30% by weight of low orientation/coarseness filaments having a linear density of tex or higher, and the filaments are bonded only mechanically.

[0008] Mechanical adhesion can be carried out by conventional methods, for example by needling or, for example, by European patent application no.
It can be carried out hydrodynamically using a fluid jet as described in US Pat. No. 108,621.

The degree of orientation of the low-orientation-coarse filaments contained in the nonwoven fabric of the present invention is determined by the ultimate tensile strength elongation (ul
limit tensile strength
xtension) of at least 80%, preferably at least 100%. The upper limit of the ultimate tensile strength elongation of low-orientation-coarse filaments is essentially only limited by their ability to be manufactured. However, it is advantageous to choose the degree of orientation of the filaments to give an ultimate tensile strength elongation of 100 to about 350%. Low degree of orientation - The degree of orientation of the coarse filaments, i.e. their ultimate tensile strength elongation, increases the intended purpose, i.e. in the three-dimensional shape obtained by deep drawing, the coarse filaments do not break in the drawing area, while It is particularly preferable to adapt the film to a state where no excessive residual stretchability remains. It is therefore particularly preferred to adjust the degree of orientation of the coarse filaments, ie their ultimate tensile strength elongation. To this end, after deep drawing the web of the present invention, the coarse filaments in the drawing area still have a residual extensibility of about 10 to 5.
It is adjusted so that it has 0%, especially 10 to 30%.

The coarse filaments contained in the nonwoven fabric of the present invention generally have an individual fineness of 7 to 30 dtex, preferably 1
It has a linear density of 0 to 25 dtex. It is also possible to use linear densities outside these advantageous linear density ranges, provided that the above conditions regarding the degree of orientation of the filamentary material are followed.

For certain purposes, the deep-drawn nonwoven fabric of the present invention consists of 100% low-orientation-coarse filaments. However, it has surprisingly been found that in accordance with the present invention it is possible to produce webs that are easy to deep draw and contain up to 70% other fibers. These "other fibers" represent any type of fiber known to be suitable for web production. They preferably have a moderate to high degree of orientation and therefore a moderate to high tensile strength, and they are staple fibers or preferably continuous fibers. The term "other fibers" should therefore always be understood to mean all these types of fibers.

Known webs exhibit only moderate deep drawability and tear in the drawing region at high deep drawing ratios. In contrast, it was unexpected that the web of the present invention containing only 30% of low orientation-coarse filaments was still easy to deep draw. The reason why the web of the present invention containing a main proportion of other fibers has good deep drawability is that the low orientation and coarseness filaments present in the web provide a surprisingly good supporting and stabilizing effect. This is believed to be due to the fact that this is surprisingly effective in preventing breakage of other fiber portions of the web of the present invention. Preferred nonwoven fabrics of the invention contain a proportion of 40 to 85% by weight of low-orientation-coarse filaments or, as mentioned above, they are 100% low-orientation-coarse filaments.

It is not necessary that the low-orientation-coarse filaments and other fibers of the nonwoven fabrics of the present invention all have the same linear density. Rather, two or more groups of low-orientation-coarse filaments with a linear density of 7 dtex or more may be present in the same nonwoven fabric, or the linear density of the low-orientation-coarse filaments may be randomly distributed within a range of 7 dtex or more. You can leave it there. However, their degree of orientation corresponds to at least 80% of the ultimate tensile strength elongation.

The same, of course, applies to the other fibers of the nonwoven fabric according to the invention. They may also be present in the same nonwoven fabric at different linear densities or in a linear density spectrum with randomly distributed linear densities, but they are not subject to linear density limitations of 7 dtex or more. Therefore, the linear density of these "other fibers" may be 7 dtex or less, and generally they are 1 to 7 dtex.
It is 30dtex. By linear density mixing of low-orientation-coarse filaments and other fibers, the properties of the nonwoven fabrics of the invention can be varied over a fairly wide range. For example, a relatively high proportion of low-orientation-coarse filaments increases stiffness and reduces opacity. Furthermore, a relatively high proportion of fine-grained filaments of 10 dtex or less is particularly preferred when it is desired to increase the opacity of the nonwoven fabric of the present invention and/or when it is desired to make it more homogeneous.

In the nonwoven fabric for deep drawing of the present invention, the distribution patterns of the low-orientation-coarse filaments and other fibers are diverse. The low-orientation-coarse filaments and other fibers are present as a substantially homogeneous mixture within the deep-drawn nonwoven, so that on average the distribution of the low-orientation-coarse filaments and other fibers decreases by the volume of the web. They may be approximately equal for each element. However, it is also possible for the deep-drawn nonwoven fabric of the invention to have a layered structure, with the low-orientation coarse filaments and other fibers being present in separate layers. These layers of low orientation-coarse filaments and layers of other fibers are arranged in alternation. In the case of such a structure, it is preferred that at least one outer layer, especially both outer layers, of the laminated nonwoven fabric is a layer of low-orientation-coarse filaments. These layers of the nonwoven fabric of the invention are also preferably bonded mechanically, for example by needling.

The excellent support provided by the deep draw nonwoven fabrics of the present invention can also be exploited by combining the nonwoven fabrics of the present invention with other known nonwoven fabrics in local or uniform bonding. In this case too, a laminated structure is obtained, which exhibits good deep drawability due to the presence of at least one layer of the nonwoven fabric of the invention. When combining the laminate material of the present invention with other known laminate materials, there is in principle no limit to the number of layers, which is determined by the intended use. Such combinations generally consist of alternating nonwovens of the invention and conventional nonwovens, and may include the nonwovens of the invention or conventional nonwovens as outer layers on one or both sides.

The basis weight of the nonwoven fabric of the present invention is also essentially determined by the intended use of the material, and is generally from 50 to 500 g/m2, preferably from 100 to 300 g/m2.
It is m2.

The excellent formability of the nonwoven fabric of the present invention is not only due to the good formability of the low orientation/coarseness filaments contained therein, but also because the filaments are bonded purely mechanically. This is also due to the improved mobility of the filament. Similarly, the higher bulk of mechanically bonded nonwovens compared to thermally bonded filaments is advantageous for many applications.

The coarse individual filaments contained in the nonwoven fabric of the present invention impart good self-stability to the deep-drawn product, even when it does not contain, or does not yet contain, a stabilizing resin. .

The nonwoven fabric for deep drawing (spunbond) of the present invention can be produced by forming filaments as a randomly deposited web on a moving perforated surface using a conventional method. Produced by a method consisting of using at least 30% by weight of coarsely oriented filaments. The jet for pulling the filament in this case has an ultimate tensile strength elongation of at least 80%, preferably at least 10%.
Adjustments are made to impart a relatively low degree of pre-orientation to these coarse filaments, corresponding to 0%. Depending on the intended use of the deep-drawn nonwovens according to the invention, it is particularly advantageous to adjust the injection jet in such a way that the low-orientation-coarse filaments have an ultimate tensile strength extension of 100 to 350%. . Preferably, the linear density of the low-orientation-coarse filaments is between 8 and 30 dtex, and their proportion in the total weight of the web is between 80 and 100% by weight. The amount of filament deposited per m2 is determined according to the criteria mentioned above. Generally 50 to 500 g, preferably 100 to 300 g of filament are deposited per m2.

[0021] The filament preferably comprises a rotating impingement plate,
In particular, it is deposited using a downstream guide plate as described, for example, in German Patent No. 2,713,241. Low degree of orientation
In order to produce the deep-drawn nonwoven fabric of the present invention with a preferred layered structure in which coarse filaments and other fibers are present in different layers, low-orientation-coarse filaments and other fibers are deposited alternately. A method is used in which the filaments are deposited by means of a plurality of successive (aligned in the transport direction of the perforated surface) rows of deposition members. The freshly deposited nonwovens are bonded in conventional manner by mechanical means, e.g. by needling or by hydrodynamic adhesion methods using fluid jets, e.g. as described in EP-A-0 108 621. .

[0022] The filaments and fibers of the deep-drawn nonwoven fabric of the present invention may in principle be composed of any spinnable polymeric material. However, the polymeric material from which the low-orientation-coarse filaments are made must be at least 80%
, preferably at least 100%, especially 100-350
% ultimate tensile strength elongation. Other fibers optionally present in the webs of the present invention are not subject to such limitations.

Preferred polymeric raw materials for making the deep draw nonwoven fabrics of the present invention are polyester, polyamide and polyacrylonitrile. Particularly preferred are polyesters, especially those consisting at least 80% of terephthalic acid and ethylene glycol monomers. Particularly preferred are polymeric raw materials consisting of pure polyethylene terephthalate or of polyethylene terephthalate without more than 5% of modifying monomers.

The polyester building blocks that may be present in the polyester used, as well as terephthalic acid and ethylene glycol, are those customary in spinnable polyesters. For example, p-isophthalic acid, sulfoisophthalic acid, naphthalene carboxylic acid, aromatic hydroxycarboxylic acid, such as p-hydroxybenzoic acid, about 4 to 1 carbon atoms.
0 aliphatic dicarboxylic acids such as adipic acid, glycols having 3 to 10 carbon atoms, diglycols, triglycols and polyglycols.

The invention furthermore provides a deep-drawn nonwoven fabric of the above type impregnated with a thermoplastic or thermosetting resin. Thermoplastic or thermosetting resins are preferably used to stiffen the nonwoven to an extent that it becomes self-supporting. Particular preference is given to nonwoven fabrics according to the invention impregnated with known thermosetting resins, especially phenolic resins or melamine resins. The resin pick-up, ie the amount of resin applied per square meter of fibrous material, depends on the intended use and is preferably determined to produce an essentially open-pore web network. An open-pore web network essentially maintains the open-pore structure of the original web for purposes of the present invention;
The resin is a material that completely or partially covers only the individual filaments and forms bonding points at the intersections of the filaments. The appropriate amount of resin impregnation is 20 to 8 of the semi-finished product.
0% by weight, preferably 40-50% by weight. Within this range, the amount of resin is advantageously further adapted to the weight per m 2 of the nonwoven fabric according to the invention. When using the high basis weight nonwoven fabrics of the invention, the amount of resin is preferably in the upper half of the above range, whereas when using lightweight fibrous materials it is in the lower half. In certain applications, it may also be advantageous to increase the resin pickup to such an extent that a resin film remains between the threads of the web network even in the stretched state.

The resin-impregnated nonwoven fabric for deep drawing of the present invention can be easily produced by treating the above-mentioned nonwoven fabric with a conventional resin impregnation method. The resin can be applied in conventional manner by brushing, rubbing, knife coating, padding or dipping. Advantageously, the nonwoven fabric is then passed through a pair of squeezing rolls to squeeze it to the desired resin impregnation level. In a preferred form, the resin is applied by the "reverse method". In this case, the resin is first applied uniformly to the transfer material. This resin-containing transfer material is then brought into uniform intimate contact with the deep drawing nonwoven fabric of the present invention, and the resin is drawn from the transfer to the nonwoven fabric by the capillary forces of the latter.

Of course, it is not necessary to uniformly apply the resin over the entire area of the nonwoven fabric. Rather, the resin can also be applied in a regular pattern or in an irregular but statistically uniform distribution. However, in this case it is necessary to limit the extent of the area that is not impregnated with resin to ensure that the entire 3D printed or unformed sheet material is still adequately stiffened. Must be kept in mind.

For example, by applying resin to the nonwoven fabric of the present invention using the above-mentioned reverse method, the resin can be effectively distributed randomly. In this case, the nonwoven fabric has a laminated structure and contains predominantly low-orientation-coarse fibers on one side and predominantly finer regular or highly oriented filaments on the other side. In this case, the resin is applied from the coarse side, the coarse filaments absorb the main amount of resin, and after deep drawing and hardening of the resin a particularly effectively stiffened support network is formed.

The thermoplastic resin for impregnation is advantageously applied in the form of a solution or preferably an emulsion. Advantageously, the thermosetting resin is applied as a commercially available highly concentrated aqueous solution or dispersion.

The resin-impregnated or non-impregnated deep-drawable nonwoven fabrics of the invention are particularly advantageously used in the production of three-dimensionally shaped fibrous sheet materials. These three-dimensional structures likewise form part of the subject matter of the present invention. They consist of three-dimensionally shaped open-pore nonwoven fabric. At least 30% by weight of the filaments of the nonwoven fabric are low-orientation-coarse filaments that only stretch below their ultimate tensile strength elongation, ie, do not break, even in the shaped areas. They also contain a support network with relatively coarse pores. The network is formed by low-orientation-coarse filaments, more highly elongated in the region of deformation, and may also be stiffened by thermoplastic or thermoset resins. In the case of the three-dimensionally shaped fibrous sheet materials of the present invention which do not consist solely of low-orientation-coarse filaments, the spaces between the relatively coarse openings of the support network are filled with numerous, if desired likewise resin-stiffened, fibrous sheet materials. occupied by a porous web with microscopic openings. These numerous microscopic apertures are formed from other filaments that are clearly thinner. In certain cases, but less preferred due to higher weight, the pores of the shaped nonwoven may be filled with a thermoplastic or thermosetting resin.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in more detail below with reference to the drawings.

FIG. 1 schematically shows a structure obtained by three-dimensionally modeling the sheet material (3) of the present invention. From this figure, it can be seen that there are many wells (5) drawn from the fiber base surface (4) (nonwoven fabric).

FIG. 2 shows one of the wells (5) of the structure of FIG.
FIG.

For clarity, FIGS. 1 and 2 schematically show only the support network formed by low-orientation-coarse filaments; in each case only the well surface facing the viewer is shown, and the pores are The far side visible through the open nonwoven structure is not shown. FIG. 2 shows particularly clearly and schematically the open spaces between the fibers of an open-pore nonwoven structure.

A particular form that is particularly useful for subsequent use as a core material for the production of laminate materials is that the three-dimensionally printed sheet-like fibrous material of the present invention has a large number of regular ridges on the fibrous base surface. be. In another form, the three-dimensional building material of the present invention has a large number of regular ridges and depressions on the fiber base surface. The ridges and depressions take the form of wells with round or square bases or, for example, lands, which advantageously each have a flat top and a flat bottom, preferably all of these surfaces lying in the same plane. and parallel to the fiber base plane.

The three-dimensionally shaped sheet-like fibrous material of the present invention can be produced by processing the resin-treated nonwoven fabric of the present invention by a conventional deep drawing method, or by deep-drawing the non-resin-treated nonwoven fabric of the present invention. It is produced by drawing and then treating the obtained three-dimensional shaped structure with a resin, or by deep drawing the untreated nonwoven fabric of the present invention together with a resin film of an appropriate sheet weight.

The present invention further provides a sheet-like sandwich article comprising two rigid outer cover layers bonded to each other via a core of three-dimensionally shaped resin-reinforced sheet-like fibrous material according to the invention as described above. . The adhesion of the cover layer to the top surface of the ridge or the bottom surface of the depression of the core material of the invention is carried out by conventional lamination methods using an adhesive, in particular a cold-curing or heat-curing adhesive, such as an epoxy resin or a thermosetting resin. It can be carried out. The adhesive bond was found to be extremely stable due to the large contact area between the core material and the cover layer. Even though the core materials of the present invention are open-pore nonwoven structures, sandwich articles made using them unexpectedly combine high compressive strength and extremely low weight. They are therefore suitable as interior structural materials for vehicle compartments, especially aircraft compartments. In this case, it is particularly preferable that the three-dimensionally shaped fibrous nonwoven fabric of the present invention is made of a flame-retardant filament material.

FIG. 3 shows the cover surfaces (7) and (8) and the core (9) made of the three-dimensionally printed sheet material of the present invention.
) a sandwich structure (6) is shown.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one form of a structure formed three-dimensionally from the sheet material of the present invention.

FIG. 2 is an enlarged schematic view of one of the wells of the structure of FIG. 1;

FIG. 3 is a schematic diagram showing a sandwich structure with a core made of the three-dimensionally shaped sheet material of the present invention.

[Explanation of symbols]

3 Sheet material of the present invention 4 Fiber base surface 5 well 6 Sandwich structure of the present invention 7, 8 Cover surface

Claims (22)

[Claims] Claim 1: An isotropic deep-drawn fabric comprising at least 30% by weight of low-orientation-coarse filaments with a linear density of 7 dtex or more, and configured as a filament nonwoven fabric to which the filaments are only mechanically bonded. Non-woven fabric that is easy to mold. 2. Nonwoven fabric according to claim 1, wherein the degree of orientation of the coarse filaments corresponds to at least 80%, preferably at least 100% of the ultimate tensile strength elongation. 3. The low-orientation-coarse filaments individually have a linear density of 7 to 30 dtex.
The nonwoven fabric according to at least one of the above. 4. The nonwoven fabric according to claim 1, wherein the proportion of low-orientation-coarse filaments is 40 to 85% by weight. 5. The nonwoven fabric according to claim 1, comprising only low-orientation-coarse filaments. 6. A nonwoven fabric according to claim 1, wherein the low-orientation-coarse filaments and other filaments are present as a substantially homogeneous mixture. 7. The low-orientation-coarse filaments and other filaments are present primarily in separate layers in the nonwoven fabric, the layers being mechanically bonded.
5. The nonwoven fabric according to at least one of items 5 to 5. Claim 8: 50 to 500 g/m2, preferably 1
The nonwoven fabric according to at least one of claims 1 to 7, having a basis weight of 00 to 300 g/m2. 9. The nonwoven fabric according to claim 1, which is further combined locally or uniformly with other known nonwoven fabrics. 10. A method of manufacturing the nonwoven fabric of claim 1 by forming the filaments into a randomly deposited web by conventional methods, the nonwoven fabric having an individual linear density of 7 dtex.
The method comprises using at least 30% by weight of low-orientation-coarse filaments having a high degree of orientation and coarseness, and bonding the filaments constituting the web purely mechanically. 11. The filaments are deposited by a plurality of consecutive rows of depositing members (aligned in the conveying direction of the web conveying means) which alternately deposit low-orientation-coarse filaments and other filaments. 10. 12. The isotropic, deep-drawable nonwoven fabric according to claim 1, further impregnated with a thermoplastic or thermosetting resin. 13. The resin pick-up amount is determined to produce an essentially open pore nonwoven network.
2. The nonwoven fabric that can be easily deep drawn. 14. The method of claim 12, comprising producing a nonwoven fabric for deep drawing according to claim 10, and then impregnating this nonwoven fabric with a thermoplastic or thermosetting resin.
A method for producing a resin-impregnated nonwoven fabric that is easy to deep draw. 15. A three-dimensionally shaped open-pore nonwoven fabric, wherein at least 30% by weight of the filaments are low-orientation-coarse filaments that only stretch below their ultimate tensile strength elongation even in the deformed region. . 16. The three-dimensionally shaped open-pore nonwoven fabric according to claim 15, further reinforced with a thermoplastic or thermosetting resin. 17. The three-dimensional structure according to claim 15, which comprises providing a large number of regularly arranged ridges and depressions by deep drawing the nonwoven fabric for deep drawing according to claim 1. manufacturing method of non-woven fabric. 18. By deep drawing the nonwoven fabric for deep drawing according to claim 1 together with a resin film,
17. The method for producing a three-dimensionally shaped resin-reinforced nonwoven fabric according to claim 16, which comprises providing a large number of regularly arranged ridges and depressions. 19. A method according to claim 17, which comprises producing a three-dimensionally shaped nonwoven fabric by the method according to claim 17, and then impregnating this nonwoven fabric with a thermoplastic or thermosetting resin and curing it as necessary. 16. The method for producing a three-dimensionally shaped nonwoven fabric according to item 16. Claim 20: Claim 12 by deep drawing method.
17. The method for producing a three-dimensionally shaped nonwoven fabric according to claim 16, which comprises imparting a large number of regularly arranged ridges and depressions to the resin-impregnated nonwoven fabric for deep drawing according to claim 16. 21. A sheet-like sandwich article comprising two rigid outer cover layers bonded to each other through a core of lightweight material, the core comprising a three-dimensionally printed resin reinforced web according to claim 16. The said article consisting of. 22. A method comprising producing a three-dimensionally modeled resin-reinforced web by the method according to any one of claims 17 to 20, and then applying a cover layer to both sides of the web by a conventional method. A method for producing a sandwich article according to item 21.