LU100793B1 - PROCESS FOR PRODUCING THERMOPLASTIC PREIMPREGNE - Google Patents

Abstract

The present invention relates to a process for producing thermoplastic prepreg which is developed for use as a structural and visual material in all industrial fields, mainly aviation, defense industry and automobile, and which allows that the thermoplastic resin is impregnated in the sewn fabric formed with a reinforcing thread (A). The object of the present invention is to provide a process for producing thermoplastic prepreg which makes it possible to apply a more precise quantity of resin to the stitched fabrics comprising a reinforcement thread (A) and a thermoplastic thread (B), and to be treated more easily.

Description

PROCESS FOR PRODUCING THERMOPLASTIC PREIMPREGNE

Field of the invention

The present invention relates to a process for producing thermoplastic prepreg which is developed for use as a structural and visual material in all industrial fields, mainly aviation, defense industry and automobile, and which allows that the thermoplastic resin is impregnated into the sewn fabric formed with a yarn which is made from reinforcing fibers.

Background of the invention

Prepregs are divided into two main categories, namely thermosetting and thermoplastics. The thermoplastic prepreg is a structure composed of thermoplastic resin-impregnated yarns made from reinforcing fibers. Thermoplastic prepregs are very popular today because of their light weight, their recycling potential, and their resistance to corrosion properties.

Today, the resin used in the production of thermoplastic prepreg is applied as a powder, a film or granules. The thermoplastic prepregs that are obtained are then converted to a composite material which is the final product with production processes such as thermoforming, heat compression and pressure molding or overmolding.

In a thermoplastic prepreg production, materials such as polyamides (PA) (polyamide 6 (PA6), polyamide 6,6 (PA66), polyphthalamide (PPA)), polyphenylene sulfide (PPS), polysulfone (PSU), poly (arylene ether sulfone), polyolefins (polyethylene (PE), polypropylene (PP), etc.), polyimide (PI), polyesters, preferably such as poly (ethylene terephthalate) (PET) ) or a poly (butylene terephthalate) (PBT), a poly (ether ether ketone) (PEEK) can be used.

Manual or automatic methods are preferred for feeding the resin in the form of powder, film and granules into the system. Specially applications of powder and granules used in a production of thermoplastic prepreg cause a problem of homogenization during the distribution of the resin, a difficulty in the use of an optimum raw material, and a large amount of waste occurring during from production.

The production of thermoplastic prepreg is carried out with discontinuous or continuous processes. In both batch and continuous processes, even in the case where the supply of the resin in powder form is automatic, the ratio of thermoplastic resin / reinforcing fiber can not be applied to the desired accuracy. Variations occur in the amounts of powder used per unit area. In the case where it is fed in the form of granules, since the resin particle sizes are too large, accumulations occur since a homogeneous fusion can not be performed on the thermoplastic prepreg. Impregnation of the resin in the fiber structure is not easy for the same reason. In other words, the resin can not penetrate the structure composed of a yarn made from a reinforcing fiber homogeneously.

U.S. Patent No. US5445701, a known application in the state of the art, discloses a process of thermoplastic resin in film form. However, this method is expensive, as well as difficulties in supplying the compatible film for the desired thermoplastic material can be encountered.

In U.S. Patent No. US20140030582, a known application in the state of the art, the wall thickness of the thermoplastic prepregs of the present invention can be produced in a range of 0.3 and 6.0. mm. Said invention can operate in a limited field since it is not for thermoplastic prepregs with a greater thickness of walls.

U.S. Patent No. US5464684, a known application in the state of the art, discloses a process for producing the polyamide-based hybrid yarn. In this process, a thermoplastic yarn and a reinforcing yarn are produced by mixing with each other by applying air. Given the complexity of the yarn mixing process and the application of a twisting process on a carbon fiber which is very brittle, this causes a decrease in the linear strength of the carbon fiber. Summary of the invention

The object of the present invention is to provide a process for producing thermoplastic prepreg which allows the resin used in the prepreg application to penetrate more into the sewn fabric than conventional applications, in other words which allows the wettability of the web formed with a thread that is made from a reinforcing fiber.

Another object of the present invention is to provide a process for producing thermoplastic prepreg which makes it possible to apply a more precise quantity of resin to the stitched fabrics comprising a reinforcing thread and a thermoplastic yarn and also to offer an easier treatment of them.

Detailed description of the invention

The "thermoplastic prepreg application method" developed to achieve the objects of the present invention is illustrated in the accompanying figures, in which:

Figure 1 is the view of the sewn fabric used for a unidirectional thermoplastic prepreg made with the thermoplastic prepreg application method of the invention.

Figure 2 is a view of the sewn fabric used for a triaxial thermoplastic prepreg made with the thermoplastic prepreg application method of the invention.

Figure 3 is a view of the sewn fabric used for a biaxial thermoplastic prepreg made with the thermoplastic prepreg application method of the invention.

Figure 4 is the view of the sewing thread (C) used in the process for applying thermoplastic prepreg of the invention.

The components shown in the figures each receive reference numbers as follows: A. Reinforcement wire B. Thermoplastic wire C. Sewing thread

A unidirectional thermoplastic prepreg is obtained in a manner disclosed in the invention, for example, after stitching the fabrics with a sewing thread in order to maintain the unidirectional webs made from a thermoplastic yarn used in a first and a last layer sewn fabric and the fabric made from a unidirectional reinforcement yarn used in the middle layer of the same sewn fabric shown in Figure 1.

The types of stitching used in the production of stitched fabric can be chain, knit and the like.

The process for producing unidirectional, biaxial, triaxial or multiaxial thermoplastic prepreg which allows the resin to penetrate the fabric in a homogeneous and deep manner in a resin impregnation process performed to reinforce the stitched fabric which is manufactured, and includes the steps of - sewing with the sewing thread to combine the thermoplastic yarns and the reinforcing yarns determined in a thermoplastic prepreg design during the fabric production phase, - setting up each of the unidirectional layers fabricated with a reinforcing thread comprising a thermoplastic yarn on its lower and / or upper surface, - being composed of at least two layers so that at least one of the layers will comprise a layer including a "unidirectional reinforcing fiber", - increase of the temperature of the cloth sewn above the softening point or the point of fusion of the thermoplastic yarn, - application of a pressure (0-100 bar (s)) on the fabric sewn at this temperature, - application of a pretension (0-5 g / tex) on the fabric sewn at this temperature, - penetration of the thermoplastic resin in the form of yarn between the fibers of the reinforcement yarn in the fabric by melting, - application of the temperature and pressure over a period of time in a range of 2-120 minutes, - obtaining the final product ready use by cooling until it reaches a temperature below the glass transition temperature (Tg) of the resin without pressure or under pressure.

In the present invention, the thermoplastic yarns used in forming the sewn fabric are used in the form of a thermoplastic yarn (B) selected from a group comprising polyamides (such as polyamide 6 (PA6), polyamide 6,6 (PA66), polyphthalamide (PPA)), poly (phenylene sulfide) (PPS), polysulfone (PSU) (such as poly (ethersulfone) (PES), poly (arylene ether sulfone)), poly ( arylene sulfide), a fluoropolymer, a polyacetal, a polycarbonate, a styrenic polymer, polyolefins (such as polyethylene (PE), polypropylene (PP)), polyimide (PI), poly (etherimide), polyesters, preferably poly (ethylene terephthalate) (PET) or poly (butylene terephthalate) (PBT), polyetheretherketone (PEEK), polyetherketone (PEK), or combinations thereof -this.

In said invention, as a reinforcement yarn (A) used in the formation of the stitched fabric, a yarn produced from a material selected from the group consisting of a glass fiber, a carbon fiber, an aramid fiber , a natural fiber, or a combination thereof is used.

The term "sewn fabric" used in the invention is defined as a system composed of one or more layers of unidirectional fibers, and formed by holding these layers together for sewing with a non-structural sewing thread. , preferably a sewing thread made from a thermoplastic polymer. When the angles of the one-dimensional layers forming the stitched fabrics, the fabrics can be unidirectional, biaxial, triaxial or multiaxial.

The term "dtex" used in the invention is the weight in grams per 10,000 meters of yarn. The term "tex" used in the invention is the weight in grams per 1,000 meters of yarn.

In the thermoplastic prepreg production method of the invention, the resin being in the form of a yarn made from a thermoplastic fiber allows the resin amount ratio / reinforcing fiber in the thermoplastic prepreg to be easily adjusted. .

In the present invention, the wall thickness of the thermoplastic prepregs which are the final products formed by penetrating the resin into the sewn yarn is adjusted to be in a range of 0.25 and 8 mm. The wall thickness of the thermoplastic prepregs comprising a single layer reinforcing fiber depends on the type of reinforcement yarn used, the web weft weight and the pressure applied. The wall thickness of thermoplastic prepregs made from sewn fabric obtained by holding the system comprising at least one "single layer reinforcement thread" and produced as at least two layers together with a non-structural sewing thread is dependent on many of the unidirectional fiber layers used, the type of reinforcing wire, the surface weight of the sewn fabric and the pressure.

The present invention includes the application of 0-100 bar (s), preferably in a range of 1-40, of pressure on the resin at the step of heating the resin.

In the present invention, the cooling of the resin penetrating the reinforcing threads of the sewn fabric is carried out at 0-100 bar (s) of pressure, preferably in a range of 1-40 bar (s) pressure.

In the present invention, the weight of the thermoplastic resin is in a range of 10% to 90%, preferably 30% to 70%, of the weight of the yarn made from reinforcing fibers.

In a preferred embodiment of the invention, to allow unidirectional thermoplastic prepreg (UD) production, unidirectional and single layer reinforcement yarns (A) and layers comprising a thermoplastic yarn (B) on a lower surface and / or higher of said layer are used.

In a preferred embodiment of the invention, in order to allow production of biaxial thermoplastic prepreg, two-layer biaxial (A) reinforcement yarns and layers comprising a thermoplastic yarn (B) on lower surfaces and / or upper of said layers are used.

In a preferred embodiment of the invention, to allow triaxial thermoplastic prepreg production, triaxial and three-layer reinforcing yarns (A) and layers comprising thermoplastic yarn (B) on lower surfaces and / or upper of said layers are used.

In a preferred embodiment of the invention, to allow multiaxial thermoplastic prepreg production, at least quadriaxial and four-ply reinforcement yarns (A) and layers comprising a thermoplastic yarn (B) on lower surfaces and or higher of said layers are used.

In a preferred embodiment of the invention, the sewn fabric is obtained by sewing at least two woven fabrics, which are obtained by weaving a thermoplastic yarn and a reinforcing thread together, with a sewing thread. together.

The thermoplastic prepregs of the invention can be used as a structural and visual material in all industrial fields, mainly aviation, the defense industry and the automobile. The final product that is obtained is the semi-finished product called the thermoplastic prepreg or organic sheet.

In the production of thermoplastic prepreg, discontinuous or continuous processes may be used. The main principle used in both processes is to apply a pressure (0-100 bar (s)) at a temperature above the softening or melting point of the thermoplastic resin, and to allow the resin to be impregnated into the reinforcing fibers in this way. A cooling process is applied after the temperature and pressure have been applied for a specified time between 2 minutes and 120 minutes. A cooling process can be applied without pressure or under pressure (0-100 bar (s)) depending on the structure of the polymer. The cooling temperature is below the glass transition temperature (Tg) of the resin. The machine in which the thermoplastics of the invention are produced can be heated up to 450 ° C depending on the plastic structure. The temperature range that can be used in the cooling process is between 25 ° C and 200 ° C. The wall thickness of the thermoplastic prepregs of the invention is in the range of 0.25 mm to 8 mm. The known applications in the state of the art can not allow that the resin is impregnated homogeneously in the fibers. On the other hand, in the process of the invention, since the resin is used in wire form, the resin / fiber reinforcing ratio can be precisely adjusted. In summary, with the newly developed method, a quantity homogenization of resin is provided before the start of the process. In order to provide the ratio resin / reinforcing fiber homogeneously at a ratio desired anywhere, the different dtex, the different diameters of filaments and the number of son produced from thermoplastic fibers can be used. With the application of thermoplastic yarns, increasing the plastic surface area and even material orientation allow the resin to be melted more easily especially with respect to powder and pellet applications. Thus, a product with superior quality can be obtained in a machine that has less accuracy. At the same time, defects relating to the surface weight of the resin that may appear during application are prevented.

The thermoplastic resins used in the application of sewn fabric are applied in the form of yarn on different layers of the fabric. The yarns made from reinforcing fibers (fiberglass, carbon, aramid, natural, etc.) are applied in single layer or in different layers of the fabric in the same way, and the hybrid structure obtained is prepared to be suitable for thermoplastic prepreg production. Two or more types of reinforcing threads (A) may be used in hybrid fabrics. For example, a carbon, glass and thermoplastic wire (B) can be used in the same sewn fabric.

Within the scope of the process of the invention, the raw material of the thermoplastic prepreg is obtained from the web comprising a reinforcement thread (A) and a thermoplastic thread (B) from the multiaxial textile production machine which is commonly used. Thus, there is no additional process step required such as conventional thermoplastic prepreg production when applying powder coating, film or granules, and thus production is performed more quickly.

In the production of thermoplastic prepregs, stitched fabrics comprising reinforcing yarn (A) and thermoplastic yarn (B) can be processed in more precise amounts of resin and can be processed more easily. The thermoplastic composite structure that is the final product can easily meet the strength values required with the design of sewn fabric layers. By means of the types of stitched fabric which are designed differently, thermoplastic prepregs with different mechanical properties can be obtained. By this means, the composite structure can be varied compatible with the field of use of the end user. The application of stitched fabric is suitable for use in a wide range of application fields since it allows the placement of the reinforcing thread on different axes.

Claims (8)

CLAIMS AMENDED A process for producing thermoplastic prepreg material characterized by the steps of a) sewing together at least two layers of fabric which comprise reinforcing yarns and thermoplastic yarns wherein the ratio of the weight of said thermoplastic yarns to the weight of said yarns at least 10% reinforcement; b) impregnating said thermoplastic yarns into said fused web of said thermoplastic yarns at or above the softening or melting temperature of said thermoplastic yarns and application of a pressure in the range of 0 -100 bar (s) on said fabric sewn during said impregnation process, c) cooling said impregnated sewn fabric to a temperature below the glass transition temperature of said thermoplastic yarns and applying a pressure in the range of 0- 100 bar (s) on said fabric sewn during said cooling process. 2. A process for producing a thermoplastic prepreg according to claim 1, characterized in that said thermoplastic yarns are composed of a polyamide, a polyolefin, a poly (ether ketone), a poly (ether ether ketone), a polyimide, a poly (etherimide), a poly (arylenecétone), a poly (arylènesulfone), a poly (arylèneéthersulfone), a poly (arylene sulfide), a fluoropolymère , a polyacetal, a polycarbonate, a styrenic polymer, a polyester or combinations thereof. 3. A method of producing thermoplastic prepreg according to claim 1, characterized in that said reinforcing son (A) used in the formation of said fabric are made from a material selected from the group including glass, carbon, an aramid or a natural fiber, or a combination thereof. 4. Process for producing thermoplastic prepreg according to any one of the preceding claims, characterized in that said sewing threads are thermoplastic. 5. A process for producing thermoplastic prepreg according to any preceding claim, characterized in that said / said layer (s) of reinforcing son and said layer (s) of thermoplastic son are unidirectional. 6. A process for producing a thermoplastic prepreg according to claim 5, characterized in that said unidirectional layers comprise said sewn fabric which are obtained as unidirectional, biaxial, triaxial or multiaxial by sewing them with different angles with respect to each other. . 7. A method of producing thermoplastic prepreg according to claim 5, characterized in that the layers of said fabric comprising said unidirectional reinforcing son are formed of son of the same type or hybrids. 8. Process for producing thermoplastic prepreg according to claim 1, characterized in that said sewn fabric comprises woven fabrics which are obtained by weaving of thermoplastic yarn and reinforcing thread.