CN108659524B - Low-fiber-floating long glass fiber reinforced polyamide composite material and preparation method thereof - Google Patents
Low-fiber-floating long glass fiber reinforced polyamide composite material and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
- C08J5/0405—Reinforcing macromolecular compounds with loose or coherent fibrous material with inorganic fibres
- C08J5/043—Reinforcing macromolecular compounds with loose or coherent fibrous material with inorganic fibres with glass fibres
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J2377/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J2377/06—Polyamides derived from polyamines and polycarboxylic acids
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2477/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J2477/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2477/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J2477/06—Polyamides derived from polyamines and polycarboxylic acids
Abstract
The invention discloses a low-fiber-floating long-glass-fiber reinforced polyamide composite material and a preparation method thereof, wherein a second polyamide resin with a specific content and a specific structure is added into a common first polyamide resin, the second polyamide resin limits a specific monomer 1, 4-cyclohexyl dicarboxylic acid for synthesis and the content thereof, particularly limits the content of 1, 4-cyclohexyl dicarboxylic acid trans-conformation, and the second polyamide resin is blended with the first polyamide resin, a polyhydroxy component and long glass fibers, so that the long-glass-fiber reinforced polyamide composite material with good mechanical properties such as rigidity and toughness, good appearance such as fiber floating and excellent weather resistance can be obtained, and the preparation method is simple and easy to operate and is convenient to popularize and apply.
Description
Technical Field
The invention relates to a polyamide composite material, in particular to a low-floating-fiber long glass fiber reinforced polyamide composite material and a preparation method thereof, belonging to the technical field of modification and preparation of high polymer materials.
Background
Polyamides have excellent mechanical properties, heat resistance, chemical resistance, self-lubricity, good processability and the like, and are therefore widely used in the fields of automobiles, home appliances, electronic appliances, electric tools and the like. In particular, in the automobile industry, the use of plastics instead of metal materials to reduce the weight of automobiles and reduce emissions is an important measure for environmental problems, and therefore, in order to achieve light weight of automobiles, polyamide materials are widely applied to interior and exterior trims, structural functional parts and the like of automobiles, so that higher performance requirements for polyamide materials, including heat resistance, fatigue resistance, creep resistance, excellent product appearance and the like, are provided, and particularly, the requirements for the performance of polyamide materials applied to high-temperature environments around engines are more urgent.
In general, in order to obtain more outstanding characteristics of mechanical property, heat resistance, fatigue resistance, creep resistance and the like, other reinforcing fillers such as glass fibers and the like are used for reinforcing and filling the resin matrix, and the material cost can be reduced. Compared with the short glass fiber reinforced modification, the long glass fiber modified material has the outstanding characteristics of higher strength, modulus, impact strength, fatigue resistance, creep resistance and the like, but also brings adverse effects on the surface appearance of parts and the loss of processing equipment. Traditional polyamide materials such as PA6 and PA66 belong to semi-crystalline materials, and the high crystallinity and the high crystallization rate of the traditional polyamide materials influence the movement of resin molecular chain segments and are not beneficial to the infiltration of resin on the surface of glass fiber, so that the problem is severe for long glass fiber reinforced polyamide products, and poor infiltration of the glass fiber can cause negative effects such as fiber floating appearance defect, mechanical property attenuation and the like.
In addition, in order to obtain more outstanding performances such as mechanical property, heat resistance, fatigue resistance, creep resistance and the like, the resin matrix is reinforced and filled with reinforcing fillers such as long glass fibers, and conventional nylon resin and high-temperature nylon resin can be blended and modified. The high-temperature nylon resin used therein is currently more common to synthesize PA6T with a higher melting point by adding terephthalic acid in the polymerization process of a conventional aliphatic diacid and aliphatic diamine system, the high-melting point nylon material can greatly improve the mechanical properties of nylon, such as heat resistance, fatigue resistance and creep resistance, but because PA6T has a melting point (370 ℃) higher than the conventional processing temperature, the nylon material is decomposed in the processing process, the nylon resin is copolymerized with other monomers (such as PA6, PA66 and PA6I monomers) to form a PA6T copolymer to reduce the melting point (220-; the common high-temperature nylon resin at present is also high-temperature nylon PA46 which is obtained by copolymerizing butanediamine and adipic acid and has a higher melting point, but has the problems of high water absorption and poor dimensional stability.
In addition, when the high-temperature nylon and the conventional nylon are used for blending modification, the problems of improving the compatibility between the conventional nylon and the high-temperature nylon, improving the difference between processing windows of the high-temperature nylon and the conventional nylon, adverse effects (such as fiber floating on the surface of a product and poor glossiness) brought by the glass transition temperature and the high crystallization temperature of the high-temperature nylon on the appearance of the product, and deterioration of ageing properties such as weather resistance and the like are also needed to be solved.
Disclosure of Invention
In order to solve the technical problems, the invention provides a low-fiber-floating long glass fiber reinforced polyamide composite material and a preparation method thereof.
The technical scheme of the invention is as follows:
the application discloses low fine long glass fiber reinforcement polyamide combined material that floats, this polyamide combined material mainly include first polyamide resin, second polyamide resin and long glass fiber.
The first polyamide resin10-50 wt.% of the total weight of the first, second polyamide resin, and the repeating structural units of the first polyamide resin mainly compriseDicarboxylic acid monomerAnddiamine monomerAnd (3) a repeating structural unit formed by copolymerization.
Dicarboxylic acid monomerIs composed ofAliphatic dicarboxylic acidsAndaromatic dicarboxylic acidsAt least one of1, 4-cyclohexyl radical Dicarboxylic acidsA mixture of (a).
Wherein at least one of aliphatic dicarboxylic acid and aromatic dicarboxylic acid accounts for 40-90% of the total mole percentage of dicarboxylic acid monomer. Wherein the aliphatic dicarboxylic acid accounts for 80-100% of the total mole percentage of the aliphatic dicarboxylic acid and the aromatic dicarboxylic acid, and the aliphatic dicarboxylic acid is at least one of adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, glutaric acid, pimelic acid and suberic acid, and can also be derivatives of the aliphatic dicarboxylic acid with two unchanged carboxyl activities; wherein the aromatic dicarboxylic acid accounts for 0-20% of the total mole percentage of the aliphatic dicarboxylic acid and the aromatic dicarboxylic acid, and the aromatic dicarboxylic acid is at least one of terephthalic acid, isophthalic acid and naphthalene dicarboxylic acid, and can also be derivatives of the aromatic dicarboxylic acid with two unchanged carboxyl activities. The preferred aliphatic dicarboxylic acid is adipic acid, and the preferred aromatic dicarboxylic acid is at least one of terephthalic acid and isophthalic acid.
Wherein the 1, 4-cyclohexyl dicarboxylic acid accounts for 10-60 percent of the total mole percentage of the dicarboxylic acid monomer, and the preferred content is 20-50 percent; more particularly, 1, 4-cyclohexanedicarboxylic acid has a trans conformation and a cis conformation, and the proportion of 1, 4-cyclohexanedicarboxylic acid in the trans conformation to the total mole percentage of 1, 4-cyclohexanedicarboxylic acid is not less than 60%. The trans conformation of 1, 4-cyclohexanedicarboxylic acid mainly affects the alignment regularity of the segments of the first polyamide resin, and when the content of 1, 4-cyclohexanedicarboxylic acid in the trans conformation is less than 60%, the segments of the first polyamide resin formed affect the toughness of the final material.
Diamine monomerAre butanediamine, hexanediamine, 2-methylpentanediamine, 1, 5-pentanediamine, nonanediamine, undecanediamine, dodecanediamine, 2, 4-trimethylhexanediamine, 2,4, 4-trimethylhexanediamine, 5-methylnonanediamine, 1, 3-bis (aminomethyl) cyclohexane, 1, 4-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2-bis (4-aminocyclohexyl) propane, bis (aminopropyl) piperazine, aminoethylpiperazine, bis (p-aminocyclohexyl) methane, 2-methyloctanediamine, trimethylhexanediamine, 1, at least one of 8-diaminooctane, 1, 9-diaminononane, 1, 10-diaminodecane, 1, 12-diaminododecane, m-xylene dimethylamine and p-xylene dimethylamine, and also derivatives thereof in which the two amine groups of the diamine monomer have no change in activity;preferably hexamethylenediamine.
In actual operation, the nylon can be hydrolyzed by using hydrobromic acid, and subjected to trimethyl silanization and then gas chromatography, and the types and the contents of the different monomers can be judged according to the positions and the intensities of chromatographic peaks.
The repeating structural unit of the first polyamide resin may include a repeating structural unit derived from polymerization of an aminocarboxylic acid monomer including, but not limited to, amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and p-aminomethylbenzoic acid, or a lactam monomer, in addition to the repeating structural unit derived from copolymerization of a dicarboxylic acid monomer and a diamine monomer; lactam monomers include, but are not limited to, lactams such as caprolactam, laurolactam, and the like.
The first polyamide resin described herein has a number average molecular weight of 1w to 5 w. The number average molecular weight can be measured by gel permeation chromatography, using hexafluoroisopropanol as a solvent and polymethyl methacrylate (PMMA) as a standard sample, to test the number average molecular weight of the copolyamide. In the synthesis of the first polyamide resin, as one of the common synthetic means, adding a blocking agent to control the molecular weight is a means commonly used in the art, and monofunctional carboxylic acids, amines, isocyanates, alcohols, esters, and anhydrides are generally used as the blocking agent.
The melting point of the first polyamide resin described herein is 220-300 ℃. The melting point is heated according to ISO11357-3 by Differential Scanning Calorimetry (DSC) to eliminate heat history, then cooled to room temperature at 10 ℃/min and then heated at 10 ℃/min, and the temperature obtained at the maximum endothermic peak in the second heating process is the melting point. When the melting point of the first polyamide resin is higher than 300 ℃, the first polyamide resin is not beneficial to the long glass fiber reinforced polyamide composite material to obtain better appearance, and the higher melting point also requires higher processing temperature, so that the heat resistance requirement on other components is higher; and when the melting point of the first polyamide resin is lower than 220 c, the heat resistance and mechanical properties of the final polyamide composite material are lowered.
The first polyamide resin described herein may be synthesized using known conventional polyamide synthesis techniques. For example, polycondensation is carried out by heating at a high temperature of 150 ℃ to 300 ℃ in which the monomer is present in the form of a solution or in the form of a solid salt, and the pressure of the system is increased by dehydration of the monomer by polycondensation due to the high temperature at the initial stage of the synthesis. Removing water vapor under reduced pressure, heating the oligomer or salt under normal pressure or negative pressure, and completing polymerization at a temperature not higher than the melting point of the polymer. The apparatus for carrying out the polymerization of the above-mentioned first polyamide resin is not particularly limited, and known apparatuses such as engaging devices, extrusion reaction devices, drum reaction devices, autoclave reaction devices and the like can be used, but these are generally required to provide a reaction chamber in a high-temperature and negative-pressure environment and to provide a melt polymerization reaction time of a sufficient length of time.
The second polyamide resinThe polyamide resin composition comprises 50-90 wt.% of the total weight of the first and second polyamide resins, and the second polyamide resin is at least one of polyamide formed by copolymerizing at least one of dicarboxylic acids other than 1, 4-cyclohexyldicarboxylic acid and diamine, polyamide formed by polymerizing aminocarboxylic acid, and polyamide formed by polymerizing lactam. The second polyamide resin is at least one of PA46, PA56, PA66, PA6, PA11, PA12, PA610, PA612, PA1010, PA1012, PA1212 and PAMXD 6; preferably at least one of PA66, PA6, PA610, PA612, PA1010, PA11 and PA 12; more preferably PA66, PA6 and PA 610; the second polyamide resin may be chosen from polyamides containing aromatic or cycloaliphatic structures, preferably PA10T, PA6C (poly-1, 4-hexanediamine cyclohexyldicarboxylate). When the weight proportion of the second polyamide resin is less than 50%, part of the mechanical properties and the chemical corrosion resistance of the composite material are affected; when the weight ratio of the second polyamide resin is more than 90%, toughness such as elongation at break, weather resistance of the composite material are not significantly improved.
The long glass fiberIs 5-50 μm in diameter, preferably 7-20 μm in diameter. Smaller diameter means a larger aspect ratio of the final fiber in the composite, greater resin to fiber contact area and greater strength than a composite of equivalent fiber contentAlso have higher mechanical properties, but may also result in more difficult production and subsequent processing. The long glass fibers are preferably present in the form of glass fiber bundles, also referred to as rovings, preferably comprising 500-8000 glass filaments per bundle, more preferably 1000-4000 glass filaments per bundle, and having a linear density of 1000-3000tex, i.e. a weight of 1000-3000g per 1000 m of glass fiber bundle.
In order to improve the compatibility and dispersion effect between the first and second polyamide resins, the low-floating-fiber long glass fiber reinforced polyamide composite material further comprises the polyamide resin in an amount of 0.025-10 wt.% based on the total weight of the first and second polyamide resinsPolyhydroxy Composition (I)The polyhydroxy component is a compound and/or polymer having at least two hydroxyl functional groups, and is preferably at least one of a diol, a triol and a polyol having a hydroxyl functional group number of not less than four. Wherein the polyol having two hydroxyl functional groups includes, but is not limited to: at least one of 1, 2-ethanediol, 1, 3-propanediol, 2, 3-butanediol, 1, 5-pentanediol, 2-dimethyl-1, 3-propanediol and polyether glycol; wherein the polyol having three hydroxyl functional groups includes, but is not limited to: glycerol, trimethylolpropane, 2, 3-bis (2 '-hydroxyethyl) cyclohexan-1-ol, 1,2, 6-hexanetriol, 1,1, 1-tris- (hydroxymethyl) ethane, 3- (2' -hydroxyethoxy) propane-1, 2-diol, 3- (2 '-hydroxypropoxy) propane-1, 2-diol, 2- (2' -hydroxyethoxy) hexane-1, 2-diol, 6- (2 '-hydroxypropoxy) hexane-1, 2-diol, 1,1, 1-tris [ (2' -hydroxyethoxy) methyl]Ethane, 1,1, 1-tris [ (2' -hydroxypropoxy) methyl group]At least one of propane, 1,1, 1-tris (4' -hydroxyphenyl) ethane, 1,1, 1-tris (hydroxyphenyl) propane, 1,1, 3-tris (dihydroxy-3-methylphenyl) propane, 1,1, 4-tris (dihydroxyphenyl) butane, 1,1, 5-tris (hydroxyphenyl) -3-methylpentane, ditrimethylolpropane, trimethylolpropane ethoxylate, trimethylolpropane propoxylate and trihydroxypolyether compounds (e.g. diethylene glycol, triethylene glycol); polyols and/or polymers containing at least four hydroxyl functional groups include, but are not limited to: 1,1,3, 3-tetra (methoxy) propane, pentaerythritylAt least one of alcohol, dipentaerythritol, tripentaerythritol, polyvinyl alcohol with a certain degree of polymerization, ethylene vinyl alcohol copolymer and dendritic hyperbranched polyester, wherein "with a certain degree of polymerization" means that the number average molecular weight of the polymer is more than 2000. The addition of the polyhydroxy component promotes the compatibility and dispersion among the first polyamide resin and the second polyamide resin, and plays a great promoting role in improving the mechanical property and the toughness of the final composite material by exerting the first polyamide resin. When the amount of the polyhydroxy component added is less than 0.025 wt.%, the effect of improving the compatibility is not obvious, and the effects of improving the toughness, increasing the elongation at break and improving the impact strength of the composite material cannot be achieved; when the polyhydroxy component is added in an amount of more than 10 wt.%, it has a relatively significant negative effect on the heat resistance as well as strength and rigidity of the composite material.
The polyhydroxy component in the application not only improves the compatibility and the dispersion effect of polyamides with different structures, but also finds that the polyhydroxy component can improve the binding force between long glass fibers and polyamide resin. The polyhydroxy component added in the production process of the long glass fiber reinforced polyamide composite material is used for promoting the infiltration effect of the long glass fiber, the bonding force between the long glass fiber and the polyamide can be greatly improved by adding the polyhydroxy component, so that the long glass fiber can be better dispersed in the production process, and the defects caused by poor dispersion of the long glass fiber in resin in the later molding process, such as loss of mechanical properties, obvious fiber floating in appearance or undispersed glass fiber bundles distinguishable by naked eyes, are reduced. The prior art discloses the use of highly branched poly (alpha-olefins) such as polyethylene wax, modified low molecular weight polypropylene, mineral oils such as paraffin or silicon, and any mixtures of these compounds to improve the dispersion and impregnation of long glass fibers, but the long glass fiber impregnating compounds disclosed therein do not have any significant effect on the improvement. According to the application, the polyhydroxy component is applied to the long glass fiber reinforced polyamide composite material, particularly when polyamide systems with different structures are contained, the compatibility among resins can be improved, the first polyamide resin is promoted to play a role in improving the toughness, weather resistance and product surface appearance of the polyamide composite material, the infiltration effect of the resin on the long glass fiber is promoted, and the high strength and rigidity such as tensile strength and bending strength are shown. Compared with the long glass fiber reinforced polyamide composite material with the same addition amount, the long glass fiber reinforced polyamide composite material using the polyhydroxy component has excellent appearance, such as the improvement of the surface gloss of the product and the reduction of the fiber floating degree, and simultaneously has the effect of obviously improving the tensile strength and the elongation at break. Furthermore, another outstanding benefit is obtained with the polyhydroxy component, the long glass fiber polyamide composition using the polyhydroxy component has excellent processability, and improved appearance and physical properties are also obtained at relatively lower processing temperatures compared to long glass fiber reinforced polyamide compositions without the polyhydroxy component. In contrast, the conventional long glass fiber reinforced polyamide composition without the polyol component shows severe fiber floating in appearance and a certain reduction in tensile strength and elongation at break due to the decrease in processing temperature. The polyhydroxy component can be used together with polyethylene wax with high branching degree, modified low molecular weight polypropylene, mineral oil and other substances which are used for improving the dispersion of glass fibers or regulating the flow behavior of a melt, so that the aim of regulating the fluidity of the composite material is fulfilled.
The low-fiber-floating long glass fiber reinforced polyamide composite material also comprises at least one of a lubricant, a nucleating agent, a crystallization promoter, a crystallization inhibitor, a flame retardant, a flow modifier, a chain extender, a mold release agent, a colorant, a pigment, a dye, an antistatic agent, a conductive filler, a stabilizer, an antioxidant, a filler and a nano filler. The lubricant is preferably at least one of glyceryl monostearate, glyceryl tristearate, ethylene bis stearamide, ethylene bis lauramide, ethylene bis oleamide, low molecular weight ionomer, ethylene-acrylic acid copolymer, and ethylene-vinyl acetate copolymer.
The application also discloses a low-floating-fiber long glass fiber reinforced polyamide composite material and a preparation method thereof, wherein the preparation method comprises the following steps:
(1) accurately weighing each component in the low-floating-fiber long glass fiber reinforced polyamide composite material, mixing and plasticizing the other components except the long glass fiber by melt mixing equipment with the processing temperature of 280-330 ℃, and conveying the components into a high-temperature melt calendering and impregnating mold with the processing temperature of 280-330 ℃, wherein the melt mixing equipment is a screw extruder, preferably a double-screw extruder;
(2) and (3) drawing the long glass fiber into a mold with the length of 2-4m at the speed of 100-150m/min, fully calendering and impregnating, cooling and granulating to obtain the low-floating-fiber long glass fiber reinforced polyamide composite material.
The beneficial technical effects of the invention are as follows: the long glass fiber reinforced polyamide composite material is prepared by adding a second polyamide resin with a specific content and a specific structure into a common first polyamide resin, wherein the second polyamide resin limits a specific monomer 1, 4-cyclohexyl dicarboxylic acid for synthesis and the content thereof, particularly limits the content of trans-conformation of the 1, 4-cyclohexyl dicarboxylic acid, and the second polyamide resin is mixed with the first polyamide resin, a polyhydroxy component and long glass fibers to obtain the long glass fiber reinforced polyamide composite material with good mechanical properties such as rigidity and toughness, good appearance such as floating fibers and excellent weather resistance.
Detailed Description
In order to clearly understand the technical means of the present invention and to implement the technical means according to the content of the specification, the following embodiments are further described in detail in the following with reference to the specific examples, which are used for illustrating the present invention and are not intended to limit the scope of the present invention.
Information on each raw material used in the following specific examples and comparative examples is described in the following table 1, wherein each composition characteristic of the first polyamide resin used is described in the following table 2.
TABLE 1 raw materials for specific examples and comparative examples
TABLE 2 compositional Properties of the first Polyamide resin
Wherein the proportion of 1, 4-cyclohexanedicarboxylic acid and adipic acid in Table 2 is the proportion of the dicarboxylic acid and the adipic acid in the total mole percentage of dicarboxylic acid monomers respectively; the trans-form proportion of 1, 4-cyclohexanedicarboxylic acid means the proportion of 1, 4-cyclohexanedicarboxylic acid in the trans-form to the total molar percentage of 1, 4-cyclohexanedicarboxylic acid; the hexamethylene diamine ratio refers to the proportion of hexamethylene diamine in the total mole percentage of diamine.
The first polyamide resin described in table 2 was prepared as follows: according to the composition characteristics of the first polyamide resin shown in table 2, a salt solution of 1, 4-cyclohexanedicarboxylic acid (in this embodiment, 1, 4-cyclohexanedicarboxylic acid is taken as an example) and other comonomer (adipic acid) is placed in a high-pressure reaction kettle, nitrogen is used to replace air in the reaction kettle, and then the salt solution is concentrated by stirring under a high temperature condition (100 ℃ to 150 ℃), water vapor in the reaction kettle is removed until the solubility of the salt solution is concentrated to about 70 wt.%, the temperature of the reaction kettle is increased to about 215 ℃, the pressure of the high-pressure reaction kettle is maintained at about 2.2MPa, the reaction is carried out for about 50 to 60 minutes until the temperature of the reaction kettle is raised to 255 ℃, and the pressure of the reaction kettle is ensured to about 2.2MPa, so as to obtain a prepolymer of the first polyamide resin; crushing the prepolymer and drying the prepolymer for about 24 hours at 100 ℃ in a nitrogen atmosphere to obtain prepolymer powder; and carrying out solid-phase polycondensation on the prepolymer powder under the nitrogen atmosphere at about 210 ℃ to obtain a first polyamide resin. The chemical reaction principle, the operation mode, the process parameters and the used raw materials mentioned in the preparation method are well known technical schemes of those skilled in the art except for the special process parameters and components, and other operations, process parameters and components such as the end-capping reagent and the like are not mentioned, and are not described in detail in the application.
The trans-conformational proportion of 1, 4-cyclohexyldicarboxylic acid in the above-mentioned first polyamide resin can be determined by high performance liquid chromatography HPLC. Using a reversed phase chromatographic column, adopting a gradient elution method, and analyzing conditions of liquid chromatography: the temperature is 40 ℃, the liquid flow rate is 1.0ml/min, the mobile phase A is deionized water containing 0.1 percent of trifluoroacetic acid, and the mobile phase B is a mixed solution of water containing 0.1 percent of trifluoroacetic acid and acrylonitrile in a weight ratio of 10: 90. Using an ultraviolet (wavelength 214nm) detector; the proportion of 1, 4-cyclohexanedicarboxylic acid in the trans-form to 1, 4-cyclohexanedicarboxylic acid can be judged according to the difference of peak positions (retention time) of the trans-form conformation and the cis-form conformation and the peak area. The specific method can dissolve 1, 4-cyclohexyl dicarboxylic acid monomer in water/acrylonitrile (50:50) to form 10mg/ml solution, and 20ml of the solution is injected, and retention time of two conformations is influenced according to gradient change program of ratio of mobile phase A to B, wherein when the ratio of mobile phase B rises from 0% to 100% in 15min, retention time of trans conformation and retention time of cis conformation are respectively located at positions of about 11 min and 14.5 min, and the proportion of trans conformation 1, 4-cyclohexyl dicarboxylic acid can be judged according to peak area.
The number average molecular weight of the above-mentioned first polyamide resin was measured by gel permeation chromatography GPC using hexafluoroisopropanol as a solvent and polymethyl methacrylate (PMMA) as a standard sample.
In order to meet the processing requirement and simultaneously facilitate comparison of influences of the components on the final performance and the processing performance of the polyamide composite material, the following specific examples and comparative examples are added with the same kind and content of lubricant, heat stabilizer and antioxidant, wherein the lubricant is pentaerythritol stearate (PETS) which accounts for 0.15 wt% of the total mass of the non-glass fiber components; the heat stabilizer is a mixture of CuI and KI in a mass ratio of 1:8, and the using amount of the heat stabilizer accounts for 0.15 wt% of the total mass of the non-glass fiber components; the antioxidant is bis (2, 6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate, and the using amount of the antioxidant accounts for 0.15 wt% of the total mass of the non-glass fiber components.
The long glass fiber reinforced polyamide composite material was prepared according to the following processing scheme I or processing scheme II in the amounts of the components shown in tables 3 to 5, wherein the polyamide and the long glass fiber in the components shown in tables 3 to 5 were measured in parts by weight, and the polyhydroxy component was measured in percent based on the total weight of the first and second polyamide resins.
Processing scheme I: accurately weighing each component, mixing and plasticizing the other components except the long glass fiber by melt mixing equipment with the processing temperature of 280-; and then drawing the long glass fiber into a mold with the length of 2-4m at the speed of 100-150m/min, fully calendering and impregnating, cooling and granulating to obtain the long glass fiber reinforced polyamide composite material.
Processing scheme II: accurately weighing each component, mixing and plasticizing the other components except the long glass fiber by melt mixing equipment with the processing temperature of 260-; and then drawing the long glass fiber into a mold with the length of 2-4m at the speed of 100-150m/min, fully calendering and impregnating, cooling and granulating to obtain the long glass fiber reinforced polyamide composite material.
The prepared long glass fiber reinforced polyamide composite material is subjected to mechanical property test, appearance evaluation and weather resistance test, and the test method comprises the following steps:
and (3) testing mechanical properties: according to ISO527-1/2 standard, molding the long glass fiber reinforced polyamide composite material into a test sample strip with the thickness of 4mm by using an injection molding machine, sealing the sample strip by using an aluminum foil bag to prevent the sample strip from absorbing moisture (namely, keeping the sample strip in a dry state), and testing the tensile strength and the elongation at break of the sample strip under the condition of testing speed of 23 ℃ and 5 mm/min; the dry specimens were tested for notched Izod impact strength at 23 ℃ according to ISO180/1 eA.
Appearance evaluation: the degree of fiber floating in appearance was evaluated mainly. Five engineers familiar with the appearance quality of the parts are selected and trained as evaluation groups: under the same process conditions, the compositions in examples and comparative examples were molded into sheets of 100mm × 100mm × 4mm, and the appearance was rated "very poor" (80%), "poor" (< 80% and ≧ 60%), "medium" (< 60% and ≧ 30%), "good" (< 30% and ≧ 10%), "excellent" (< 10%) depending on the area of the floating fiber appearing in the sheet appearance as the total surface area.
The method for evaluating weather-resistant accelerated aging comprises the following steps: according to the American society for automotive society SAE J2527, the xenon lamp aging-simulating material is subjected to an outdoor weathering process including environmental factors such as light environment, dark environment, spraying stage, drying stage, heating, etc., and the change in surface color difference (. DELTA.E) and change in gray scale after exposure of 2500kJ/m2 (about 1900h) of the sheets molded from the compositions of examples and comparative examples are evaluated, and the smaller the gray scale or the larger the change in color difference, the worse the weathering performance of the material.
The results of the above performance tests are shown in the performance columns below the corresponding columns for each of the specific examples and comparative examples in tables 3 to 5.
TABLE 3 compositions and Properties of specific examples 1-4 and comparative examples 1-6
The polyamide shown in table 3 is obtained by mixing the first polyamide resin and the second polyamide resin according to the ratio shown in table 3, wherein the ratio refers to the percentage of the first polyamide resin and the second polyamide resin in the total weight of the first polyamide resin and the second polyamide resin. As can be seen from table 3, the use of a blend of a first polyamide resin containing a specific proportion of trans-configured 1, 4-cyclohexanedicarboxylic acid having a specific structure with a conventional polyamide resin (second polyamide resin) results in a composite material having improved tensile strength, elongation at break and impact strength, and further, significantly improved weather resistance, and a slightly improved product appearance, compared to the use of only a conventional polyamide resin (second polyamide resin) (examples 1 to 4 and comparative example 1). It can also be seen from Table 3 that the improvement effects of mechanical properties and weather resistance are more remarkable when the content of the first polyamide resin is 10 to 50% in the proportion of the total content of polyamide resins (practical example 1 and practical example 4), and the improvement effects of mechanical properties, weather resistance and appearance are very insignificant and very close to the results of comparative example 1 when the content of the first polyamide resin is less than 10% (comparative example 2); when the content ratio is more than 50% (comparative example 6), it adversely affects the mechanical properties, weather resistance and appearance of the composite material, indicating that the first polyamide resin needs to have a specific content to exert its intended effect. It can also be seen from Table 3 that when the content of 1, 4-cyclohexanedicarboxylic acid in the first polyamide resin is 10 to 60% (examples 1 to 3), the mechanical properties and weather resistance are improved to some extent, but when the content is less than 10% (comparative example 5) and the content is more than 60% (comparative example 4), although the weather resistance is improved to some extent with respect to comparative example 1, the elongation at break, impact strength and fiber floating are slightly improved with respect to comparative example 1, but are in a very poor state. Finally, as can be seen from Table 3, when the 1, 4-cyclohexanedicarboxylic acid in the trans configuration in the first polyamide resin is contained in an amount of not less than 60%, it has good elongation at break and weather resistance (specific examples 1,2 and 3), and when the 1, 4-cyclohexanedicarboxylic acid in the trans configuration is contained in an amount of less than 60% (comparative example 3), the regularity of the arrangement of the segments of the first polyamide resin is affected due to the trans configuration, so that the toughness of the composite material is lowered, which is manifested in that the elongation at break is very poor and also the weather resistance is affected.
TABLE 4 compositions and Properties of specific examples 5-8 and comparative examples 7-9
The polyamide in table 4 is obtained by mixing the first polyamide resin and the second polyamide resin according to the ratio in table 4, wherein the ratio is the percentage of the first polyamide resin to the second polyamide resin to the total weight of the first polyamide resin and the second polyamide resin; the polyhydroxy components are used in the amounts indicated in Table 4 as a percentage of the total weight of the first, second polyamide resin. As can be seen from the contents in Table 4 and Table 1, the specific examples 5 to 8, which use a certain amount of the polyhydroxy component, further improved the tensile strength, elongation at break and impact strength of the composite material, while showing more excellent appearance and weather resistance, compared to the specific example 1, which does not use the polyhydroxy component. When the content of the polyhydroxy component is less than 0.025 percent (comparative example 7), the effect of improving the compatibility is not obvious, and the functions of improving the mechanical property of the composite material, improving the fiber floating condition and improving the weather resistance can not be realized; further, when the content of the polyhydroxy component is more than 15.0% (comparative examples 8 and 9), it may adversely affect the rigidity, appearance and weather resistance in the mechanical properties of the composite material.
TABLE 5 compositions and Properties of specific example 9 and comparative examples 10-11
As can be seen from Table 5, in the case where the first polyamide resins having a specific structure described herein were used in each case, the composite material using the polyhydroxy component had excellent processability, which enabled mechanical properties, appearance and weather resistance at a lower processing temperature to be obtained at a higher processing temperature as compared with the composite material without the addition of the polyhydroxy component (see specific example 5 and specific example 9). In contrast, the composite material without the polyhydroxy component exhibited a certain fiber floating phenomenon in appearance, which was of a medium grade at a higher processing temperature (see, in particular, example 1), but when it was at a lower processing temperature, the tensile strength, elongation at break, impact strength and weather resistance were somewhat reduced, but the fiber floating phenomenon was very severe, and was reduced from the "medium" grade to the "poor" grade (see, in particular, comparative example 11).
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (4)
1. A low-floating-fiber long glass fiber reinforced polyamide composite material is characterized in that: the glass fiber reinforced polyamide composite material mainly comprises a first polyamide resin, a second polyamide resin and long glass fibers, wherein the diameter of the long glass fibers is 5-50 mu m, and the weight ratio of the total weight of the first polyamide resin and the second polyamide resin to the weight of the long glass fibers is 1: 1;
wherein the first polyamide resin is copolymerized by 1, 4-cyclohexanedicarboxylic acid, adipic acid and hexamethylene diamine, the 1, 4-cyclohexanedicarboxylic acid accounts for 20-50% of the total mole percentage of dicarboxylic acid monomers, and the proportion of the 1, 4-cyclohexanedicarboxylic acid in a trans-form conformation accounts for more than or equal to 60% of the total mole percentage of the 1, 4-cyclohexanedicarboxylic acid; the number average molecular weight of the first polyamide resin is 1w-5w, and the melting point is 220-300 ℃; and the first polyamide resin comprises 10-50 wt.% of the total weight of the first, second polyamide resin;
wherein the second polyamide resin is at least one of PA66, PA6, PA610 and PA6C, and the second polyamide resin comprises 50-90 wt.% of the total weight of the first and second polyamide resins;
the low-fiber-floating long-glass-fiber reinforced polyamide composite material also comprises a polyhydroxy component, wherein the polyhydroxy component is a compound containing at least two hydroxyl functional groups, and the amount of the polyhydroxy component is 0.025-10 wt.% of the total weight of the first and second polyamide resins.
2. The low-fiber-floating long-glass-fiber reinforced polyamide composite material of claim 1, wherein: the polyhydroxy component is at least one of dihydric alcohol, trihydric alcohol and polyhydric alcohol with the number of hydroxyl functional groups not less than four.
3. The low-fiber-floating long-glass-fiber reinforced polyamide composite material of claim 1, wherein: the low-fiber-floating long glass fiber reinforced polyamide composite material also comprises at least one of a lubricant, a nucleating agent, a crystallization promoter, a crystallization inhibitor, a flame retardant, a flow modifier, a chain extender, a mold release agent, a colorant, a pigment, a dye, an antistatic agent, a conductive filler, a stabilizer, an antioxidant, a filler and a nano filler.
4. A method for preparing the low-fiber-floating long glass fiber reinforced polyamide composite material as claimed in any one of claims 1 to 3, wherein the method comprises the following steps: the method comprises the following steps:
(1) accurately weighing each component in the low-floating-fiber long glass fiber reinforced polyamide composite material, mixing and plasticizing the other components except the long glass fiber by melt mixing equipment with the processing temperature of 280-330 ℃, and conveying the components into a high-temperature melt calendering and impregnating mold with the processing temperature of 280-330 ℃, wherein the melt mixing equipment is a double-screw extruder;
(2) and (3) drawing the long glass fiber into a mold with the length of 2-4m at the speed of 100-150m/min, fully calendering and impregnating, cooling and granulating to obtain the low-floating-fiber long glass fiber reinforced polyamide composite material.
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| CN112175388B (en) * | 2020-09-30 | 2023-08-18 | 上海金发科技发展有限公司 | Polyamide composition with high heat resistance and high melt strength |
| CN112375376A (en) * | 2020-11-27 | 2021-02-19 | 上海金发科技发展有限公司 | Polyamide composition suitable for liquid-assisted molding and preparation method thereof |
| CN112552674B (en) * | 2020-12-11 | 2022-06-07 | 天津金发新材料有限公司 | Polyamide composite material with low floating fiber and high impact strength |
| CN112876841B (en) * | 2021-01-15 | 2022-09-20 | 万华化学(四川)有限公司 | Halogen-free flame-retardant long glass fiber reinforced nylon 12 material with high RTI value as well as preparation method and application thereof |
| CN115260753B (en) * | 2021-04-30 | 2024-02-09 | 上海凯赛生物技术股份有限公司 | Long carbon chain polyamide resin composition and continuous fiber reinforced long carbon chain polyamide composite material |
| CN115785659B (en) * | 2021-09-10 | 2024-02-09 | 上海凯赛生物技术股份有限公司 | Long fiber reinforced wear-resistant self-lubricating bio-based polyamide composite material and preparation method thereof |
| CN115873400B (en) * | 2021-09-30 | 2024-04-02 | 上海金发科技发展有限公司 | PA6 composition and preparation method and application thereof |
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