JPH04227736A - Reinforcing fiberous material insert and fiber reinforced composite material - Google Patents

Abstract

PURPOSE: To provide a reinforcing insert having properties such as mechanical strength, dimensional stability, absorption like capillary activity, compatibility/ adhesion with/to a matrix resin, elasticity, and elongation and a composite material.

CONSTITUTION: A reinforcing fiber material insert which is composed of or contains the nonwoven fabric of a synthetic fiber raw material and in which at least part of the synthetic fibers are hollow fibers. At least 10 % of the synthetic fibers are hollow fibers. The hollow part of the hollow fiber exist over the whole longitudinal area of the fiber. The synthetic fibers comprise a polyester, preferably polyethylene terephthalate. The nonwoven fabric is bonded mechanically. Moreover, a fiber reinforced composite material is composed of a polymer matrix having a reinforcing insert of the fiber material. The polymer matrix is a polyester or an epoxy resin.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is made of synthetic fibers,
or reinforcing fiber material inserts comprising synthetic fibers,
The present invention relates to at least a portion of the synthetic fibers being hollow fibers, and further relates to a fiber-reinforced composite material containing the interpolation material.

0002

BACKGROUND OF THE INVENTION DE-A-30 22 255 discloses fiber-reinforced composite materials and fiber mats used for producing the composite materials. The mat is formed from non-uniform yarns produced by spinning tufts of fibres, particularly defective fibres. Since hairs and pores are present on the surface of the mat, as well as swelling and discontinuity, the adhesion between the matrix resin and the fiber mat becomes strong.

Matrix resins used in fiber reinforced composite materials are mainly polyester, epoxy, phenol,
silicone, polyethylene and cellulose resins, and their elastomers. Due to the non-uniformity of the raw materials and the structure of the staple fiber mat, this known fiber-reinforced composite material was only of moderate quality.

DE-B-12 14 193 describes an anisotropic composite material consisting of a large number of hollow filaments. The hollow filaments are embedded in the matrix in an essentially parallel arrangement and bonded at its surface.

DE-C-30 13 134 discloses a method for thermoforming and/or pressing thermoplastic fiber mats to produce shaped articles. According to this method, thermoforming occurs under conditions where the fibers are thermally softened. The essential feature of this method is that the mat used is a randomly opened web containing hollow staple fibers and continuous filaments. Hollow staple fibers and continuous filaments have obstructions at appropriate intervals to maintain airtightness. Certain incompressible elongated air cushions have fibers stabilized in their thermoplastic state to form obstacles between the fibers and to allow free molding. However, this DE-C-3
0 13 134 does not mention composite materials.

In terms of absorbing high mechanical stress,
Fiber materials are superior to polymeric materials themselves that have not been melt extruded. It has therefore been known for a long time to reinforce plastic materials with fibrous inserts in order to absorb the high mechanical stresses imposed on them. Such fibrous inserts are required to meet various properties. That is, mechanical strength, dimensional stability, absorbency such as capillary activity, compatibility and adhesion with the matrix resin, elasticity and extensibility are required. The interpolant must possess all of these advantageous properties and must maintain these properties before being processed, during processing with the matrix resin, and after the matrix resin is cured. Must be.

[0007] Since particularly high tensile strength is required, it is ideal that the modulus of elasticity of the insert is the same as that of the matrix resin, and it is desirable that it has a high degree of isotropy. Therefore, it is preferable to use a nonwoven fabric made from synthetic fibers as the reinforcing fiber material insert.

[0008] For producing reinforcing fiber material inserts for fiber-reinforced composite materials, it is particularly suitable to use synthetic fibers. This is because the mechanical properties of synthetic fibers, due to their inherent high strength and long-term stability, match very well with the mechanical properties of the matrix resin. A particularly suitable matrix-reinforcing fiber material fabric structure is a non-woven structure, ie a bonded web structure. There are two main reasons for this. One reason is that the manufacturing cost of nonwoven fabrics is very low. The other reason is that the mechanical properties are isotropic because the filaments are randomly opened. However, by arranging the fibers in a certain preferred direction, it is also possible to produce a nonwoven fabric with anisotropic mechanical properties.

Composite materials are increasingly being used for the manufacture of relatively large components such as boat hulls and automobile bodies. When using composite materials in such applications, attempts are being made to save the weight and raw materials of the composite materials without compromising their mechanical properties.

[0010] As the quality requirements of users have become increasingly strict, it has become difficult to manufacture fiber reinforced materials having all of the above-mentioned properties at low cost. and,
Various proposals have been made for producing lightweight fibrous material inserts to meet user requirements.

[0011] In cases where the above-mentioned characteristics are combined, especially when high mechanical strength is required, relatively thick
As a result, a nonwoven fabric that is heavy and expensive to manufacture becomes necessary.

0012

[Problems to be Solved by the Invention] In view of the above problems, the present invention aims to improve mechanical strength, dimensional stability, absorbency such as capillary activity, compatibility and adhesion with matrix resin, elasticity and extensibility. The objective is to provide reinforcing inserts and composite materials with the following properties.

[0013]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the inventors of the present invention have conducted intensive research and found that by containing hollow fibers in the fiber material of non-woven fabrics, it is possible to produce non-woven fabrics with low basis weight and using less raw materials. It was found that the material satisfies the requirements as a reinforcing material. A further advantage of the reinforcing material of the present invention is that the amount of matrix resin often used can be saved and the weight and cost of the reinforcing material can be reduced.

That is, the insert of the present invention is a reinforcing fiber material insert that is made of a non-woven fabric made from synthetic fibers or contains a non-woven fabric made from synthetic fibers, wherein at least one of the synthetic fibers is It is characterized in that the portion is made of hollow fibers.

[0015] The proportion of hollow fibers in a nonwoven fabric that has the desired properties may be very small depending on the case. If at least 10% of the synthetic fibers constituting the nonwoven fabric are hollow fibers, the reinforcing fiber material insert of the present invention can be produced economically and technically advantageously. However, it is generally advantageous to use reinforcing fiber material inserts consisting of non-woven fabrics containing 50 to 100% hollow fibers. If the technical requirements are very high, it may be necessary to use a nonwoven fabric made of 100% hollow fibers.

The linear density of the synthetic fibers forming the nonwoven fabric used as the reinforcing fiber material insert of the present invention is within the range of the linear density of fibers commonly used as reinforcing fiber material inserts. Therefore, the linear density is generally 0.5 to 50 dt
ex, preferably in the range of 2 to 20 dtex.

[0017] Depending on the case, fibers of different linear densities may be used in combination. Particularly in the case of a nonwoven fabric in which the proportion of hollow fibers is not 100%, the hollow fibers and the non-hollow fibers may have different linear densities. Synthetic fibers may be either continuous filaments or staple fibers. When using staple fibers, it is advantageous for the staple length to be between 2 and 20 cm. However, it is of course also possible to use non-woven fabrics containing both continuous filaments and staple fibers. For example, in order to have the desired characteristics,
Hollow staple fibers may be blended into a nonwoven fabric consisting of continuous filaments in appropriate proportions.

It is of course also possible to produce nonwoven staple fiber webs using a mixture of hollow and solid staple fibers.

The synthetic fibers constituting the nonwoven fabric used in the reinforcing fiber material insert of the present invention may have one or more hollow portions. The hollow portions are present along the length of the fiber and may be present for short or very short lengths or may be present throughout the length of the fiber. Therefore, hollow fibers for the purposes of the present invention are not only foamed fibers, but also have one or more hollow portions extending over most of the length of the fibers.
Or it includes hollow fibers having the entire area.

The proportion of hollow parts contained in synthetic fibers is an important factor. The proportion of the hollow portion of the synthetic fibers constituting the nonwoven fabric used as the reinforcing fiber material insert of the present invention is 3 to 40% by volume, preferably 5 to 20% by volume.

Suitable synthetic fibers for use in the reinforcing fiber inserts of the invention are generally spinnable polyamides, polyethylenes, polypropylenes or polyesters. It is preferable to use synthetic fibers made of polyester, and it is particularly preferable to use polyethylene terephthalate.

[0022] The nonwoven fabrics used in the reinforcing fibrous material inserts of the present invention can be essentially bonded by a variety of known methods. For example, the webs can be joined by a bonding agent. That is, the webs are immersed in a binder and then the binder is cured to join the webs. Further, the binder may be a powdery or filamentous hot-melt binder. In this case, such a binder is mixed into the web and melted by heat, joining the web to form a nonwoven fabric.

[0023] Calendering can also be used to join the webs to form a nonwoven fabric. In this case, the filaments are partially mechanically entangled and welded at the intersections of the filaments.

It is also particularly advantageous if the reinforcing fiber material insert of the invention consists of or comprises a mechanically bonded non-woven fabric. Mechanical joining methods of the webs carried out for the purposes of the invention are, for example, needling or hydromechanical methods as described in the examples of EP-A-0 108 621.

The basis weight of the reinforcing fiber material insert of the present invention is:
Of course, it varies depending on the application. Generally, such a basis weight ranges from 50 to 500 g/m2, preferably from 100 to 300 g/m2.

It is further preferred that the reinforcing fiber material insert according to the invention is based on a nonwoven fabric produced by the spunbond process. In particular, a spunbond nonwoven fabric bonded by needling is preferred. It is particularly preferable that the reinforcing fiber material insert of the present invention has both the above-mentioned preferable properties.

The present invention also provides a method of manufacturing the above-described reinforcing fibrous material insert. That is, the method for manufacturing the reinforcing fiber material insert of the present invention is a method in which synthetic continuous filaments or staple fibers are opened on a moving means by a conventional method, and then joined, and the synthetic fibers to be opened are A hollow fiber is used for at least a portion of the fiber. When joining, it may be combined with another fibrous material.

When producing a nonwoven fabric made of staple fibers according to the present invention, hollow fibers are used as part of the nonwoven fabric. The mixture of hollow and solid staple fibers is then defibrated to form a web by conventional dry or wet methods and then spliced.

However, it is also possible to produce nonwovens from continuous filament and staple fiber mixtures. In this case, the staple fibers are spread while the continuous filament is being disentangled on the moving means. Either the continuous filament or the staple fiber may be a hollow fiber. The hollow continuous filament or staple fiber may be entirely or partially hollow.

Similarly, when producing a nonwoven fabric by the spunbond method, it is possible to mix hollow fibers and non-hollow fibers at the defibration stage. For example, hollow fibers are produced separately, then drawn off a bobbin creel, placed in a stream of solid fibers using a blow nozzle, and opened onto a moving means. As another method,
The spinneret for producing web-forming filaments may be provided with spinnerets for hollow fibers in addition to spinnerets for solid fibers. The number of spinnerets and the filament output ratio correspond to the desired ratio of hollow to solid fibers in the reinforcing fiber material insert. Generally, the proportion of hollow fibers in the reinforcing fiber material insert of the invention is at least 10%. And the proportion of hollow fibers is preferably 5
0 to 100%, and for maximum effect, 100% of the fibers are hollow fibers.

[0031] The webs can be bonded into a nonwoven fabric using conventional methods using binders, especially hot melt binders, calendering, or preferably needling.

The binder may be, for example, a polymeric solution, dispersion or latex. Such binders can be applied to the web by dipping the web in the binder or by spraying the web with the binder. When the liquid component evaporates, thin film adhesion points remain at the intersections of the filaments.

However, it is also possible to use thermosetting binders. Thermoset binders cure with or without the addition of heat to bond the fibers together. It is likewise preferable to use hot-melt binders. The hot melt binder is introduced into the web in powder form or preferably in fibrous form. The web is then heated to a temperature above the melting point of the binder to form bond points at the intersections of the fibers. By cooling this, a nonwoven fabric with webs bonded thereto can be obtained. Similarly, if the web is calendered at a temperature near the melting point of the filaments, the webs can be joined by adhesion at the intersections of the filaments.

[0034] Furthermore, it is preferable to mechanically join the webs. This is because no chemical or thermal load is placed on the filament. Therefore, various physical properties imparted to the filament during the filament spinning process, such as high-speed spinning and drawing processes, are retained even after the filament is made into a nonwoven fabric.

The reinforcing fibrous material insert of the present invention may consist of only one type of nonwoven fabric as described above. Alternatively, it may further contain a fiber material in addition to the nonwoven fabric. Such are, for example, other non-woven fabrics or additional layers of fibrous material (for example, an expanded structure of oriented filaments to obtain greater strength in a particular direction, or a decorative layer). By providing such additional layers, the nonwoven fabric can be made into a fiber composite material suitable for other purposes.

The present invention also provides a novel fiber-reinforced composite material, as described above, consisting of a polymeric matrix with reinforcing inserts of fibrous material. The fiber-reinforced composite material for the present invention consists of a polymeric matrix which is a thermoplastic resin or preferably a crosslinkable resin. Preferably, the polymeric matrix is a crosslinkable polymeric material known primarily for the production of fiber-reinforced composite materials. Such are, for example, polyester, epoxy, phenolic or silicone resins. Particularly suitable crosslinkable polymeric materials are crosslinkable polyesters and epoxy resins. These resins are crosslinked using crosslinking agents or by reaction with heat or eg ionizing radiation.

The fiber-reinforced composite material of the present invention can be produced by a conventional method. That is, it is manufactured by dipping or coating. Particularly preferred is a coating method. An uncrosslinked matrix polymer is applied to both sides of the reinforcing fibrous material insert of the present invention, and the insert is then deposited in a press, draw, or mold to form the desired shape. Thereafter, the polymer material is cured and crosslinked to obtain a fiber-reinforced composite material.

Claims (16)

[Claims] 1. A reinforcing fiber material insert consisting of a non-woven fabric made from synthetic fibers or comprising a non-woven fabric made from synthetic fibers, wherein at least a portion of the synthetic fibers are hollow fibers. For textile material inserts. 2. A reinforcing fiber material insert according to claim 1, wherein at least 10% of the synthetic fibers are hollow fibers. 3. A reinforcing fiber material insert according to claim 1, wherein 50 to 100%, preferably 100%, of the synthetic fibers are hollow fibers. 4. The reinforcing fiber material insert according to claim 1, wherein the hollow portion of the hollow fiber is present over the entire length of the hollow fiber. [Claim 5] The hollow portion of the synthetic fiber is 3 to 40% by volume.
Reinforcing fiber material insert according to at least one of claims 1 to 4, preferably from 5 to 20% by volume. 6. Reinforcing fiber material insert according to claim 1, wherein the synthetic fibers consist of polyester, preferably polyethylene terephthalate. 7. The reinforcing fiber material insert according to claim 1, wherein the nonwoven fabric is bonded by a binder. 8. The reinforcing fiber material insert according to claim 1, wherein the nonwoven fabric is mechanically bonded. 9. The reinforcing fiber material insert according to claim 1, wherein the nonwoven fabric is a nonwoven fabric consisting of filaments. 10. Synthetic continuous filaments and/or staple fibers are defibrated onto a moving means in a conventional manner to form a web, and the web is then joined with or without other fibrous materials. A method for producing a reinforcing fiber material insert according to claim 1, comprising using hollow fibers as at least a portion of the defibrated synthetic fibers. Claim 11: At least one of the defibrated synthetic fibers.
11. The method of claim 10, wherein 0% is hollow fiber. 12. 50 to 100 of defibrated synthetic fibers
12. A method according to claim 10 or 11, wherein %, preferably 100%, are hollow fibers. 13. The nonwoven fabric is obtained by joining the webs using a binder or preferably by mechanical methods.
2. The method according to at least one of 2. 14. A fiber reinforced composite material comprising a polymeric matrix with reinforcing fiber material inserts, said fiber reinforced composite material comprising a reinforcing fiber material insert according to claim 1. 15. The fiber reinforced composite material according to claim 14, wherein the polymer matrix is polyester or epoxy resin. 16. Dipping or applying an uncrosslinked matrix polymer to the reinforcing fiber material insert, in particular applying the uncrosslinked matrix polymer to both sides of the reinforcing fiber material insert, and then applying the uncrosslinked matrix polymer to both sides of the reinforcing fiber material insert. 15. A method of manufacturing a fiber reinforced composite material according to claim 14 by shaping in a conventional manner a reinforcing fiber material insert coated with a matrix polymer of A method comprising using a reinforcing fibrous material insert according to claim 1 as the reinforcing fibrous material insert.