A warping-resistant low-temperature-resistant continuous fiber-reinforced thermoplastic resin and its preparation method

Abstract

The present invention belongs to the field of continuous fiber reinforced thermoplastic composite materials and discloses a warping-resistant, low-temperature-resistant continuous fiber reinforced thermoplastic resin, comprising a matrix resin and continuous fibers; the matrix resin comprises a first resin and a second resin, the first resin being a thermoplastic resin; the second resin being a derivative elastomer of the first resin and having an island effect or a co-continuous structure, the mass ratio of the first resin to the second resin being 50-90:10-50; the mass proportion of the continuous fibers in the warping-resistant, low-temperature-resistant continuous fiber reinforced thermoplastic resin being 50-80%. This product solves the problem of easy warping during product production while improving low-temperature impact resistance and enhancing the seismic resistance of the composite material. A preparation method thereof is also disclosed, which is simple to operate and can be produced using existing equipment at a low cost.

Description

Technical Field

[0001] The present invention belongs to the field of continuous fiber reinforced thermoplastic composite materials, and in particular relates to a warping-resistant and low-temperature-resistant continuous fiber reinforced thermoplastic resin and a preparation method thereof. Background Art

[0002] In recent years, continuous fiber reinforced thermoplastic composites have been widely used in the automotive, electronic and electrical fields as materials that are both lightweight and rigid. This type of fiber reinforced composite material is generally made of a matrix resin made of polypropylene or nylon reinforced by reinforcing fibers such as glass fiber, carbon fiber or aramid fiber. Many reinforced fiber composite materials on the market are mostly made in two ways: one is to prepare complex devices or sheets by laminating a single layer of composite prepreg; the other is to make it by spreading the resin film and the fiber interlayer and heating and molding. These reinforced fiber composite materials have high modulus and strength, so they can replace many metal parts. As the market trend is towards reducing product weight, more and more products are achieving lightweight substitution, but in the process of product preparation, more and more problems are revealed.

[0003] Stability of parts (no warping: the main problem of these hard materials obtained by adding glass fibers). During the cycle time of industrial products, the product has not been fully cooled and demoulded, and the warping is caused by internal constraints, and the result (or relaxation) is the deformation of the part. For these continuous fiber reinforced materials, the orientation of the fibers is fixed, and the fiber ply structure of most products is anisotropic due to the different forces on the products. The orientation of the fibers has the result of limiting the shrinkage in that direction. On the contrary, in the direction perpendicular to the fiber axis, the shrinkage is controlled by the polymer, so the shrinkage is greater, which is the main reason for the warping caused by shrinkage differences. The second is the overall shrinkage caused by the crystallinity of the resin, which is very obvious for polymers reinforced with high glass fiber content. Therefore, it is necessary to develop a thermoplastic resin that is anti-warping, low-temperature resistant, and has excellent comprehensive mechanical properties, which is of great significance to this field. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a warping-resistant low-temperature resistant continuous fiber reinforced thermoplastic resin and a preparation method thereof.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A warping-resistant and low-temperature-resistant continuous fiber-reinforced thermoplastic resin comprising a matrix resin and continuous fibers;

[0007] The matrix resin includes a first resin and a second resin, wherein the first resin is a thermoplastic resin; the second resin is an elastomer derived from the first resin; and the mass ratio of the first resin to the second resin is 50-90:10-50;

[0008] The mass proportion of the continuous fibers in the warping-resistant and low-temperature-resistant continuous fiber-reinforced thermoplastic resin is 50-80%.

[0009] The second resin is a derivative elastomer of the first resin and has an island effect or co-continuous structure. This allows the first and second resins to have some of the same components in their molecular chains, making them highly compatible and preventing the two resins from peeling off from each other. The first resin crystallizes quickly and has a high degree of crystallinity, making it more susceptible to shrinkage after cooling. The second resin crystallizes slowly and has a lower degree of crystallinity, which restrains the shrinkage of the first resin, resulting in smaller shrinkage deformation after molding and no warping. Because the second resin crystallizes at the same speed as the first resin elastomer and has a relatively lower shrinkage rate, the surface of the continuous fiber sheet will not shrink, resulting in exposed fibers, resulting in a better appearance.

[0010] The second resin is an elastomeric structure, which is formed by polymerizing the hard segment of the first resin and the soft segment of the second resin. Microphase separation will occur at the molecular microscopic level to form an island structure, that is, a structure in which one phase (island phase) is discontinuously mixed in another phase (sea phase) and looks relatively continuous, or a structure in which one phase looks relatively continuous. It can absorb impact energy and make the sheet have better toughness. The second monomer is an elastomer and has two glass transition temperatures, of which the α transition temperature is basically the same as that of the first resin, and the β transition temperature is generally the glass transition temperature of the continuous phase, of which the β transition temperature is lower than -50°C, so that the anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin of the present invention can have good impact resistance in low-cold areas.

[0011] In the aforementioned warp-resistant, low-temperature-resistant continuous fiber-reinforced thermoplastic resin, preferably, the first resin comprises any one or more of polyamide, polyester, polyphenylene sulfide, polyphenylene ether, polycarbonate, polyetherketone, polysulfideetherketone, polyetheretherketone, polyethylene, polypropylene, and polystyrene. More preferably, polyamide, polycarbonate, and polypropylene are selected.

[0012] In the above-mentioned anti-warping low-temperature resistant continuous fiber reinforced thermoplastic resin, preferably, the second resin is any one or more of polyamide elastomer, polyester elastomer and EPDM rubber.

[0013] The second resin is a block copolymer with a glass transition temperature below room temperature and some molecules constrained by ionic bonds, van der Waals forces, or molecular chain entanglement. The second resin and the first resin share a common component, with the common component comprising more than 50% by mass of the second resin. These elastomers meet the aforementioned requirements for the second resin.

[0014] More preferably, the first resin is nylon 6 (PA6), and the second resin is nylon 6 elastomer (TPAE), wherein the nylon 6 elastomer is a copolymer of nylon 6 and hydroxyl-terminated polytetramethylene ether (PTMG), containing 50% of PTMG component.

[0015] More preferably, the first resin is polyester (PET), and the second resin is polyester elastomer (TPEE), wherein the polyester elastomer is a copolymer of polyester and hydroxyl-terminated polytetramethylene ether (PTMG), containing 50% of PTMG component.

[0016] More preferably, the first resin is polypropylene (PP), and the second resin is ethylene propylene diene monomer (EPDM), wherein the EPDM elastomer is made by copolymerization of ethylene, propylene and non-conjugated diene monomers, and contains 60% propylene component.

[0017] In the present invention, the first resin is a homopolymer (e.g., nylon 6 is polycaprolactam), and the second resin is a copolymer (e.g., a copolymer of polycaprolactam and polyether). Macroscopically, both the first and second resins are nylons, compatible with each other, and will not separate. Microscopically, the second resin is polymerized from two parts: the nylon 6 portion crystallizes to form an island structure, while the polyether portion does not crystallize, forming a soft sea structure. Therefore, upon impact, the soft sea structure absorbs energy, a process known as microphase separation, providing both the rigidity of an island and the ability to withstand impact.

[0018] The above-mentioned anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin is preferably a fiber cloth formed by weaving or knitting any one or more fibers selected from the group consisting of glass fiber, carbon fiber, basalt fiber and aramid fiber.

[0019] In the above-mentioned anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin, preferably, the continuous fiber is a continuous fiber surface-treated with a coupling agent; the coupling agent is a silane coupling agent.

[0020] The above-mentioned warping-resistant low-temperature resistant continuous fiber reinforced thermoplastic resin preferably does not require a compatibilizer.

[0021] Based on a general inventive concept, the present invention also provides a method for preparing a warping-resistant, low-temperature-resistant continuous fiber-reinforced thermoplastic resin, comprising the following steps:

[0022] (1) shearing and plasticizing the first resin and the second resin, respectively, and casting and pultruding them into micron-level films to obtain a first resin film and a second resin film;

[0023] (2) weaving or knitting continuous glass fibers into cloth, surface treating the cloth with a coupling agent, and dehydrating the cloth to obtain a fiber cloth;

[0024] (3) alternately layering the first resin film and the second resin film obtained in step (1) and the fiber cloth obtained in step (2) in a predetermined order;

[0025] (4) Molding the layer obtained in step (3) to obtain the anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin.

[0026] In the above preparation method, preferably, in step (1), the thickness of the first resin film and the second resin film is 60-100 μm; in step (2), the dehydration treatment is a dehydration hot air baking dehydration treatment at 120-180° C. for 1-4 hours.

[0027] Preferably, in step (3), the second resin film is evenly distributed in the laminate; in step (4), the molding conditions are as follows: preheating temperature: 220-235°C, pressure 200kg / cm 2 ;Hot pressing temperature 240-280℃, pressure 350kg / cm 2 ; Cooling temperature 40-60℃, pressure 350kg / cm 2 , molding speed 0.20-2m / min.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The anti-warping low-temperature resistant continuous fiber reinforced thermoplastic resin of the present invention solves the problem of easy warping during product production, while improving the low-temperature impact resistance at -50°C and enhancing the seismic resistance of the composite material.

[0030] 2. The anti-warping low-temperature resistant continuous fiber reinforced thermoplastic resin of the present invention has good flexibility, can fully cope with various working conditions of the product, and improve the fatigue resistance of the product; no additional auxiliary reagents, such as compatibilizers, are required.

[0031] 3. The preparation method of the present invention is simple to operate and can be produced using existing equipment at low cost. DETAILED DESCRIPTION

[0032] In order to facilitate understanding of the present invention, the present invention will be described more comprehensively and meticulously below in combination with the specification and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0033] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0035] Example:

[0036] The invention discloses a warping-resistant low-temperature-resistant continuous fiber reinforced thermoplastic resin, wherein the continuous glass fiber cloth is selected from a warp and weft yarn density of 2400TEX and a gram weight of 800g / m 2 The plain yarn is treated with silane coupling agent before use.

[0037] In an embodiment of the present invention, the first resin is nylon 6 (PA6), and the second resin is nylon 6 elastomer (TPAE), wherein the nylon 6 elastomer is a copolymer of nylon 6 and hydroxyl-terminated polytetramethylene ether (PTMG), containing 50% PTMG component.

[0038] In an embodiment of the present invention, the first resin may also be polyester (PET), and the second resin is polyester elastomer (TPEE), wherein the polyester elastomer is a copolymer of polyester and hydroxy-terminated polytetramethylene ether (PTMG), containing 50% PTMG component.

[0039] In an embodiment of the present invention, the first resin may also be polypropylene (PP), and the second resin may be ethylene propylene diene monomer (EPDM), wherein the EPDM elastomer is made by copolymerization of ethylene, propylene and non-conjugated diene monomers and contains 60% propylene.

[0040] The specific formulas of Examples 1-9 of the present invention are shown in Table 1.

[0041] Table 1 Example formula table

[0042]

[0043] The preparation method of the present invention comprises the following steps: the resins are sheared and plasticized by a screw extruder, and then formed into a film with a thickness of 70 μm and a width of 1300 mm by cast pultrusion, the continuous glass fiber is surface treated, and then subjected to a hot air baking and dehydration treatment at 150°C for 4 hours; the glass fiber fabric, the first resin film and the second resin film are layered alternately with the glass fiber fabric and the resin in a predetermined order by a laying device, and the layering sequence is designed according to the proportion of the second resin so that the second resin is evenly interlaced in the plate. Then, the layers are laid, automatically aligned, positioned, and unwound to obtain a layer of glass fiber fabric and resin film. The layer is introduced into the molding equipment, preheated to a temperature of 220-235°C and a pressure of 200 kg / cm 2 ;Hot pressing temperature 240-280℃, pressure 350kg / cm 2; Cooling temperature 40-60℃, pressure 350kg / cm 2 , molding speed 0.10m / min, and a long continuous glass fiber reinforced polyamide composite material with a thickness of 3mm was prepared.

[0044] Warping test: Place a 1m*1m plate on a marble horizontal platform and calculate the warping amount.

[0045] The properties of Examples 1-9 of the present invention are shown in Table 2.

[0046] Table 2 Performance of the embodiment

[0047]

[0048] In general, the present invention adds an elastic component derived from the first resin to the warping-resistant and low-temperature resistant continuous fiber-reinforced thermoplastic resin. The various components have good compatibility, which solves the problem of easy warping during product production. At the same time, it improves the low-temperature impact resistance at -50°C and enhances the shock resistance of the continuous fiber-reinforced thermoplastic resin.

Claims

1. A warping-resistant and low-temperature-resistant continuous fiber-reinforced thermoplastic resin, characterized in that: including matrix resin and continuous fibers; The matrix resin includes a first resin and a second resin, wherein the first resin is a thermoplastic resin; the second resin is an elastomer derived from the first resin, the second resin is polymerized by a hard segment and a soft segment, the hard segment is made of the same material as the first resin, and the second resin undergoes microphase separation at the molecular microscopic level to form an island structure; the mass ratio of the first resin to the second resin is 50-90:10-50; The mass proportion of the continuous fiber in the anti-warping low-temperature resistant continuous fiber reinforced thermoplastic resin is 50-80%; the anti-warping low-temperature resistant continuous fiber reinforced thermoplastic resin does not contain a compatibilizer.

2. The anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin according to claim 1, characterized in that: The first resin includes any one or more of polyamide, polyester, polyphenylene sulfide, polyphenylene ether, polycarbonate, polyether ketone, polysulfide ether ketone, polyether ether ketone, polyethylene, polypropylene and polystyrene.

3. The anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin according to claim 2, characterized in that: The second resin is any one or more of polyamide elastomer, polyester elastomer and EPDM rubber.

4. The anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin according to claim 3, characterized in that: The first resin and the second resin are any combination of the following: The first resin is nylon 6, and the second resin is nylon 6 elastomer; If the first resin is polyester, the second resin is a polyester elastomer; The first resin is polypropylene, and the second resin is EPDM rubber.

5. The anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin according to claim 1, characterized in that: The continuous fibers are fiber cloths formed by weaving or knitting any one or more fibers selected from the group consisting of glass fibers, carbon fibers, basalt fibers, and aramid fibers.

6. The anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin according to claim 5, characterized in that: The continuous fiber is a continuous fiber that has been surface-treated with a coupling agent; the coupling agent is a silane coupling agent.

7. A method for preparing the warpage-resistant and low-temperature-resistant continuous fiber-reinforced thermoplastic resin according to any one of claims 1 to 6, characterized in that: The steps include: (1) Shearing and plasticizing the first resin and the second resin, respectively, and casting and pultruding them into micron-level films to obtain a first resin film and a second resin film; (2) Weaving or knitting continuous glass fibers into cloth, surface treating with a coupling agent, and dehydrating the cloth to obtain a fiber cloth; (3) Laying the first resin film obtained in step (1), the second resin film and the fiber cloth obtained in step (2) alternately in a predetermined order; the second resin film is evenly distributed in the layers; (4) Molding the laminate obtained in step (3) to obtain the anti-warping and low-temperature resistant continuous fiber reinforced thermoplastic resin.

8. The preparation method according to claim 7, characterized in that In step (1), the thickness of the first resin film and the second resin film is 60-100 μm; in step (2), the dehydration treatment is a hot air baking dehydration treatment at 120-180° C. for 1-4 hours.

9. The preparation method according to claim 7, characterized in that In step (4), the molding conditions are as follows: preheating temperature: 220-235°C, pressure 200-250 kg / cm 2 ;Hot pressing temperature 240-280℃, pressure 350-400kg / cm 2 ; Cooling temperature 40-60℃, pressure 350-400kg / cm 2 , molding speed 0.20-2m / min.

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