CN109705566B - Flame-retardant nylon 6 composition and expanded beads thereof - Google Patents
Flame-retardant nylon 6 composition and expanded beads thereof Download PDFInfo
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Abstract
The invention provides a flame-retardant nylon 6 composition, which comprises the following components: a nylon 6 base resin, a flame retardant, and optionally an antioxidant, wherein the flame retardant comprises a complex of a phosphine oxide and a transition metal salt. The foaming bead prepared from the nylon 6 base resin adopted by the invention has compact and uniform foam pores, and the compression strength of the prepared foaming bead forming body is very high; meanwhile, when the nylon 6 composition provided by the invention is used in combination with a specific flame retardant and a specific antistatic agent, a synergistic effect can be generated between the flame retardant and the antistatic agent, and the flame retardant performance and the antistatic performance are improved. The foamed bead prepared from the flame-retardant nylon 6 composition has the characteristics of good high-temperature impact resistance, static resistance, flame retardance, simple and convenient process, high closed-cell rate and controllable density.
Description
Technical Field
The invention belongs to the technical field of high polymer materials, and particularly relates to a flame-retardant nylon 6 composition and expanded beads thereof.
Background
Nylon 6(PA6) is a variety of polyamide, and the molecular structure of the nylon takes a phthalein amido (-CONH-) as a repeating unit. Polyamide is the earliest industrialized synthetic fiber, and is first industrially produced by DuPont, and the invention and development thereof promote the development of the whole polymer science and engineering. The amide group of the nylon 6 is a polar group, can form hydrogen bonds, and has large intermolecular acting force and orderly arranged molecular chains, so the nylon 6 has excellent mechanical property, good impact resistance, hardness, toughness, high crystallinity, high melting point, small friction coefficient, wear resistance, self-lubrication, good vibration absorption and noise reduction. The nylon 6 has good low-temperature performance, certain heat resistance, no toxicity, no odor, no mildew and rot, good weather resistance, certain self-extinguishing property, seawater resistance, common solvent resistance, oil resistance, no acid resistance, good electrical insulation property and easy influence of temperature, and can be used at 100 ℃. The melt of nylon 6 has good fluidity and excellent processing performance, and can be used for preparing various products by adopting a processing method of common thermoplastic plastics. Nylon 6 is an engineering plastic with excellent comprehensive performance and is widely applied to the fields of transportation, mechanical industry, electronic appliances, household appliances, instruments, office machines and the like.
Nylon 6 is a combustible material, generates a large amount of dense smoke and flame molten drops and simultaneously emits huge heat during combustion, and is very easy to cause fire. The combustion process for nylon 6 is typically: the nylon resin matrix is gradually melted and softened under the heating of flame, and after reaching a certain temperature, the nylon 6 on the surface layer starts to generate thermal decomposition under the action of oxygen, molecular chain breakage occurs, toxic combustible gas such as caprolactam, benzene and the like is generated and diffused to the periphery, and raw materials are continuously provided for combustion. The pure nylon generally has an oxygen index of 23-25% and a flame retardant rating of UL 94-V2. Flame molten drop can be generated during combustion to generate combustible gas, so that the flame molten drop is still combustible, and the flame retardant modification of nylon 6 has important significance, and the flame retardant property needs to be endowed through the flame retardant modification, so that the application range of the flame retardant modified nylon is further expanded.
Like other flame-retardant polymer materials, the current nylon 6 flame-retardant material is mainly a polymer material of a blending additive type flame retardant, but a small part of the current nylon 6 flame-retardant material is a polymer material containing a reactive structural type flame retardant. The process for preparing the nylon 6 flame-retardant material by adopting the additive flame retardant is simple, the flame retardant which can meet the use requirements is various, and the problems of dispersibility, compatibility, interfacial property, durability, toxicity and the like of the flame retardant are required to be solved; the nylon 6 flame-retardant material prepared by adopting the structural flame retardant has relative permanence, low toxicity and small influence on the performance of the flame-retardant high polymer, but the process is relatively complex.
The halogen flame retardant is an important series of flame retardants for nylon 6 flame retardant materials, and is an organic flame retardant with the largest output and dosage at present, because the halogen flame retardant has low price, small addition amount and good compatibility and stability with high polymer materials, can keep the original physical and chemical properties of flame retardant products. Although the halogen flame retardant has high flame retardant efficiency when used for the nylon 6 flame retardant material, a large amount of toxic and corrosive gas can be generated in the flame retardant process, and the halogen flame retardant has certain harm to human bodies and the environment. With the development of environmental protection concepts, their applications are increasingly limited. Therefore, the development of clean, efficient and excellent comprehensive performance halogen-free flame retardant becomes the main direction for the development of nylon 6 flame retardant material industry in future. At present, the main substitute of the halogen-containing flame retardant is a phosphorus flame retardant which has high flame retardant efficiency, low smoke, low toxicity and migration resistance. The phosphorus flame retardant can also overcome the defect that the physical and mechanical properties of the material are seriously reduced due to the over-high addition of the inorganic flame retardant, and is concerned in the nylon 6 flame-retardant modification industry.
However, the existing nylon 6 and nylon 6 expanded beads and plates prepared from the same have poor flame retardance and antistatic property, and after the nylon 6 expanded beads and plates are subjected to flame retardance and antistatic modification, the control of the appearance and the foaming ratio of the foam cell of the nylon 6 expanded material is problematic, so that the subsequent molding application is influenced. Therefore, there is a problem that research and development of a flame retardant nylon 6 composition and its expanded beads having both good flame retardant property and antistatic property are urgently needed.
Disclosure of Invention
The invention aims to solve the technical problem of providing a flame-retardant nylon 6 composition and expanded beads thereof aiming at the defects of the prior art. Meanwhile, when the flame-retardant nylon 6 composition provided by the invention is used in combination with a specific flame retardant and a specific antistatic agent, a synergistic effect can be generated between the flame retardant and the antistatic agent, and the flame retardant performance and the antistatic performance are improved. The foamed bead prepared from the flame-retardant nylon 6 composition has the characteristics of good high-temperature impact resistance, static resistance, flame retardance, simple and convenient process, high closed-cell rate and controllable density.
To this end, the present invention provides in a first aspect a flame retardant nylon 6 composition comprising: nylon 6 base resin, a flame retardant and optionally an antioxidant, wherein the flame retardant comprises a complex of a phosphine oxide and a transition metal salt.
According to the present invention, the nylon 6 base resin includes nylon 6 or a mixture of nylon 6 with other resins; preferably the other resin comprises one or more of High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), polypropylene (PP), styrene-ethylene-butylene-styrene block copolymer (SEBS), polyester and Thermoplastic Polyurethane (TPU).
According to the invention, said nylon 6(PA6) is a conventional and known compound, synthesized by hydrolytic polymerization of caprolactam, cationic polymerization or anionic polymerization.
The hydrolytic polymerization takes water as an initiator, generates aminocaproic acid through hydrolytic ring opening of caprolactam, and then generates straight-chain thermoplastic nylon 6 through polycondensation and addition reaction.
The cationic polymerization is a chain reaction for promoting the ring opening of caprolactam cations by utilizing a catalyst so as to initiate caprolactam polymerization; wherein the catalyst for cationic polymerization comprises a salt of a primary or secondary amine with a strong acid, a carboxylic acid and a Lewis acid.
The anionic polymerization is to make caprolactam monomer quickly polymerize and form to obtain nylon 6 in the presence of an activating agent and an initiating agent.
According to the invention, the phosphine oxide has the structure shown in formula I below:
in the formula I, R1、R2And R3Are the same or different and are each independently selected from C1-C18Straight chain alkyl, C3-C18Branched alkyl radical, C1-C18Straight-chain alkoxy radical, C3-C18Branched alkoxy, C6-C20Substituted or unsubstituted aromatic group and C6-C20Substituted or unsubstituted aryloxy.
According to a preferred embodiment of the invention, R1、R2And R3Each independently selected from methyl, ethyl, propyl, C4-C18Straight or branched alkyl and C6-C20Substituted or unsubstituted aromatic group; more preferably selected from C4-C18Straight or branched alkyl and C6-C18Substituted or unsubstituted aromatic groups.
According to a more preferred embodiment of the invention, R1、R2And R3Each independently selected from C4-C18Straight or branched chain alkyl and C having 1 or 2 carbon rings6-C18An aromatic group.
According to a further preferred embodiment of the inventionMode (R)1、R2And R3Each independently selected from C having a main carbon chain of 6 or more carbon atoms6-C12Straight or branched chain alkyl and substituted or unsubstituted phenyl.
According to the invention, the aromatic group may have a substituent such as a hydroxyl group, a carboxyl group or the like.
According to a further preferred embodiment of the invention, R1、R2And R3Are the same substituents. The phosphine oxide with the structure has stronger complexing ability with transition metal.
According to a preferred embodiment of the present invention, the phosphine oxide is selected from at least one of triphenylphosphine oxide, bis (4-hydroxyphenyl) phenylphosphine oxide, bis (4-carboxyphenyl) phenylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide and tridecylphosphine oxide, more preferably from at least one of triphenylphosphine oxide, trioctylphosphine oxide, trihexylphosphine oxide and tridecylphosphine oxide.
According to the present invention, the transition metal salt includes a transition metal organic salt and/or a transition metal inorganic salt, preferably at least one of a chloride, nitrate, sulfate, formate, acetate and oxalate salt of a transition metal, more preferably a nitrate. The transition metal is preferably a group VIII metal element, more preferably cobalt and/or nickel. Specifically, the transition metal salt is, for example, at least one selected from the group consisting of nickel chloride, cobalt acetate, nickel acetate, cobalt nitrate, nickel sulfate, and cobalt sulfate.
According to a preferred embodiment of the invention, the transition metal salt is cobalt nitrate and/or nickel nitrate. Both of these salts form complexes more readily with phosphine oxides, resulting in higher yields.
According to a preferred embodiment of the present invention, the complex of the phosphine oxide with the transition metal salt has the following structural formula II:
in formula II, M is a transitionA metal. R1、R2And R3And R in formula I1、R2And R3The same is true.
R4And R5Identical or different, each independently selected from formate ions (HCOO)-) Acetate ion (CH)3COO-) Oxalate ion (C)2O4H-) Halogen ion (Cl)-，Br-，I-) Nitrate ion (NO)3 -) And thiocyanate ion (SCN)-) At least one of; preferably halide, nitrate and thiocyanate ions; nitrate ions are more preferred.
According to the invention, the preparation steps of the complex comprise: stirring and mixing 1-10 parts by weight, preferably 2-5 parts by weight of phosphine oxide and 3-15 parts by weight, preferably 5-10 parts by weight of transition metal salt in an organic solvent, then carrying out microwave heating and supercritical drying to obtain the complex; the organic solvent is preferably at least one of ethanol, acetone, pyridine, tetrahydrofuran, and DMF.
Wherein the stirring speed can be, for example, 90-120rpm, the microwave power is 35-55W, the microwave heating temperature is 35-50 ℃, and the heating time is 3-4.5 hours.
In a preferred embodiment of the invention, the complex obtained after supercritical drying may be denoted as M (CHO)2)2(OPR3)2Wherein M may be Ni or Co, and R may be phenyl, hexyl, octyl or decyl.
The flame retardant nylon 6 composition according to the present invention is in an amount of 5 to 50 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the nylon 6 base resin; optionally, the antioxidant is present in an amount of 0.1 to 0.5 parts by weight, preferably 0.15 to 0.25 parts by weight.
According to the present invention, the flame retardant further comprises an inorganic flame retardant component, preferably the inorganic flame retardant component is selected from group IIA and IIIA metal hydroxides, more preferably from magnesium hydroxide and/or aluminium hydroxide. The flame retardant effect can be further enhanced by adding the inorganic flame retardant component.
According to a preferred embodiment of the present invention, the weight ratio of the complex in the flame retardant to the inorganic flame retardant component is (1-5):1, preferably (2.5-3.5): 1.
In some preferred embodiments of the present invention, the flame retardant comprises: 1 to 10 parts by weight, preferably 2 to 5 parts by weight of a phosphine oxide complex with 3 to 15 parts by weight, preferably 5 to 10 parts by weight of a transition metal salt, and 1 to 10 parts by weight, preferably 3 to 6 parts by weight of an inorganic flame retardant component.
When an inorganic flame retardant component is included, the flame retardant of the present invention may be prepared by first preparing the complex and then physically mixing the complex with the inorganic flame retardant component. The physical mixing here may be ball milling, mechanical stirring. Preferably, the homogenization is carried out by mechanical stirring, with a stirring speed of about 10 rpm.
The flame-retardant nylon 6 composition is particularly suitable for preparing thermoplastic foaming materials or molded bodies thereof, and can be used in cooperation with an antistatic agent to promote the formation of the antistatic agent, so that thermoplastic products meet the requirements of environmental protection and safety, and the flame-retardant efficiency is improved.
According to the present invention, the flame retardant nylon 6 composition further comprises a carbon nanofiber antistatic agent (conductive filler). Preferably, the carbon nanofiber antistatic agent is present in an amount of 0.1 to 10 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the nylon 6 base resin.
In some preferred embodiments of the present invention, the weight ratio of the flame retardant to the carbon nanofiber antistatic agent is (3-20):1, more preferably (6-15): 1.
According to the present invention, it is preferable that the flame retardant nylon 6 composition contains 1 to 5 wt%, for example 2 to 4 wt% of a transition metal such as nickel or cobalt. This portion of the transition metal may come from the catalyst used during the preparation of the carbon nanofiber antistatic agent. As an advantage of the present invention, the carbon nanofibers used are directly used to prepare the flame retardant thermoplastic material without removing the transition metal catalyst therefrom. Due to the existence of transition metal and other potential reasons, the carbon nanofiber used in the invention can generate synergistic effect with the flame retardant, and is beneficial to generating a compact carbon layer for blocking flame and materials, so that the addition amount of the flame retardant can be reduced, the carbon nanofiber and the flame retardant are not mutually negatively influenced after being compounded to reduce the performances of each other, and the subsequent foaming process, the foam structure and the physical properties are not influenced.
According to the invention, the purity, the length-diameter ratio, the diameter and the appearance of the carbon nano fiber are not particularly required.
The preparation method of the carbon nanofiber suitable for the present invention comprises: the carbon source is treated by acid, then forms a compound with the transition metal catalyst, and the compound is carbonized.
An exemplary method of preparing the carbon nanofibers follows.
1) The carbon source is pretreated by a mixed acid treatment method or a grinding treatment method of phosphoric acid, nitric acid and hydrochloric acid (volume ratio is 1:1:1) to obtain a pretreated substance.
Wherein the carbon source is a condensed carbon source and can be at least one of carbon asphalt, petroleum asphalt, coal pitch, coal tar, natural graphite, artificial graphite, bamboo charcoal, carbon black, activated carbon and graphene; here, the carbon source having a carbon content of 80 wt% or more is preferable, and for example, at least one of coal pitch, petroleum pitch and bamboo charcoal having a carbon content of 80 wt% or more is preferable.
2) Compounding: and compounding the pretreatment substance with a metal catalyst to obtain a compound.
The metal catalyst is preferably a sulfate, nitrate, acetate or cyclopentadienyl compound of a transition metal, preferably a group VIII metal element, such as Fe, Co or Ni, and may also be Cr.
The mass percentage of transition metal atoms and carbon sources in the metal catalyst is (35-70): 100.
The metal catalyst is preferably cobalt nitrate and/or nickel nitrate here, considering that the nitrogen element contained in the catalyst may contribute to the synergistic effect to promote the flame-retardant effect.
3) And (3) carbonization treatment: and (3) carrying out carbonization reaction on the composite at the temperature of 800-1200 ℃ under the protection of high-purity nitrogen, keeping the temperature for 0.5-5 hours, and cooling to room temperature to obtain the self-assembled carbon fiber. The temperature of the carbonization treatment is preferably 950 ℃ or 1150 ℃, and the isothermal reaction is carried out for 1.5 to 2.5 hours. No post-treatment is needed to remove the metal impurities.
Compared with the commonly used short-acting antistatic agent in the prior art, such as a high molecular polymer antistatic agent, the carbon nanofiber used in the invention is a long-acting antistatic agent and can provide a long-acting antistatic effect.
The flame-retardant nylon 6 composition can be prepared according to various methods, for example, nylon 6 base resin, the flame retardant compound, the antistatic agent, and optionally the lubricant and other additives are directly mechanically mixed in a mechanical mixing device according to the proportion, and then added into a melt blending device for melt blending granulation at the temperature of 200 ℃ and 240 ℃. Or a small amount of nylon 6 base resin can be respectively concentrated and blended with the flame retardant or the conductive filler to prepare the flame-retardant master batch and the antistatic master batch at the temperature of 200-240 ℃, then the two master batches are mixed with the nylon 6 in proportion, and granulation is carried out at the temperature of 200-240 ℃. The mechanical mixing device may be, for example, a high-speed stirrer, a kneader, or the like. The melt blending apparatus may be, for example, a twin-screw extruder, a single-screw extruder, an open mill, an internal mixer, a buss kneader, or the like. In particular, in order to prevent the nylon 6 base resin from degrading by hydrolysis, it is preferable to dry the nylon 6 base resin before kneading. In addition, in order to suppress the degradation of the nylon 6 base resin by hydrolysis, it is also possible to employ an extruder with a vent for removing humid air from the nylon 6 base resin. Removal of moisture from the nylon 6 base resin can inhibit hydrolysis of resin microparticles, prevent generation of air bubbles therein and can improve the stability of the extrusion step.
The second aspect of the present invention provides a flame retardant nylon 6 expanded bead, which is prepared by subjecting a material comprising 100 parts by weight of the flame retardant nylon 6 composition according to the first aspect of the present invention, 0.001 to 5 parts by weight, preferably 0.05 to 1.5 parts by weight of a cell nucleating agent and 0.2 parts by weight of an antioxidant to a dip foaming process.
In order to control the apparent density and cell diameter of the resulting expanded beads, a cell nucleating agent may be mixed into the nylon 6 base resin particles in advance. The cell nucleating agent includes inorganic powders such as talc, kaolin, calcium carbonate, borax, zinc borate, aluminum hydroxide and silica, and polymers such as polytetrafluoroethylene, polyethylene wax, polycarbonate, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, silicone, methyl methacrylate copolymer and crosslinked polystyrene. Preferred are talc, kaolin, calcium carbonate, borax, zinc borate, aluminum hydroxide and silica, and more preferred is kaolin.
In addition, the invention also provides a preparation method of the flame-retardant nylon 6 expanded bead, which comprises the steps of granulating the flame-retardant nylon 6 composition and expanding the obtained nylon 6 particles.
The granulation can be performed in various ways known in the art, for example, the flame retardant nylon 6 composition can be extruded into strands through one or more dies of a twin-screw or single-screw extruder and cut to obtain flame retardant nylon 6 beads, or an underwater microparticle pelletizing system can be used, the specific operation process being well known to those skilled in the art.
According to some embodiments of the invention, the granulation is carried out as follows: the flame retardant nylon 6 composition is blended with a high speed mixer, extruded through a twin screw extruder, hot-cut, and then introduced into water at 75 ℃ or lower, preferably 70 ℃ or lower, more preferably 55 to 65 ℃ to be finely cut so that the length/diameter ratio of each particle is 0.5 to 2.0, preferably 0.8 to 1.3, more preferably 0.9 to 1.1, and the average weight is 0.1 to 20mg, preferably 0.2 to 10mg, more preferably 1 to 3 mg. The length/diameter ratio described herein is an average of 200 randomly selected nylon 6 particles.
The foaming can be carried out by various conventional methods, for example, an extrusion foaming method or a reaction kettle immersion foaming method, and the nylon 6 foaming beads obtained by the reaction kettle immersion foaming method are preferably in a non-crosslinked structure, so that the nylon 6 modified material can be recycled, secondary pollution is avoided, and the requirement of circular economy is met.
According to some embodiments of the present invention, the foaming is performed by a reactor dip foaming method, which comprises the following steps:
(1) in a high-pressure kettle, uniformly mixing nylon 6 particles with auxiliary agents such as a dispersion medium, a surfactant, a dispersant, a dispersion reinforcing agent and the like;
(2) covering the autoclave tightly, discharging residual air in the autoclave by using an air discharging method, namely using a foaming agent, then continuously feeding the foaming agent into the autoclave, starting heating and primarily adjusting the pressure until the foaming agent is stable, then stirring the autoclave at a stirring speed of 50-150rmp, preferably 90-110rmp, and heating the autoclave at a constant speed to a temperature which is 0.1-5 ℃, preferably 0.5-1 ℃ lower than the expansion stability;
(3) adjusting the pressure in the autoclave to a pressure required for foaming, the pressure being 1-10MPa, preferably 3-5MPa, raising the temperature to a foaming temperature at an average heating rate of 0.1 ℃/min, the foaming temperature being 0.1-5 ℃, preferably 0.5-1 ℃ lower than the melting temperature of the microparticles, and continuously stirring for 0.1-2 hours, preferably 0.25-0.5 hours under the conditions of foaming temperature and pressure;
(4) the discharge port of the autoclave was opened to discharge the contents of the autoclave into a collection tank to obtain nylon 6 expanded beads, and carbon dioxide gas was fed while discharging so that the pressure in the autoclave was maintained at about the foaming pressure before all the particles were completely foamed and entered the collection tank.
In the present invention, the pressures are gauge pressures.
In the above-mentioned dipping foaming method in the reaction kettle, a Differential Scanning Calorimeter (DSC) is used to perform a temperature rise test (from 50 ℃ to 300 ℃, the temperature rise rate is 10 ℃/min) on the flame-retardant nylon 6 composition particles, the temperature corresponding to the temperature rise curve is the melting temperature of the flame-retardant nylon 6 composition particles, and the foaming temperature is 0.1-5 ℃ lower than the melting temperature.
The dispersion medium may be any of various existing components capable of dispersing the nylon 6 particles therein without dissolving the nylon 6 particles, and for example, may be at least one of water, ethylene glycol, glycerin, methanol, ethanol, and the like, and water is particularly preferable. Further, the amount of the dispersion medium may be 1000-.
The surfactant may be any of various conventional components capable of promoting dispersion of nylon 6 particles in a dispersion medium, and for example, may be at least one of stearic acid, sodium dodecylbenzenesulfonate, quaternary ammonium compound, lecithin, amino acid, betaine, fatty acid glyceride, sorbitan fatty acid, polysorbate, and the like, and sodium dodecylbenzenesulfonate is particularly preferable. Further, the surfactant may be used in an amount of 0.001 to 10 parts by weight, preferably 0.01 to 5 parts by weight, and more preferably 0.1 to 0.5 parts by weight, relative to 100 parts by weight of the nylon 6 particles.
The purpose of the dispersant addition is to prevent the nylon 6 particles from melt-bonding to each other during foaming. The dispersant may be an organic dispersant or an inorganic dispersant, and is preferably an inorganic dispersant. The inorganic dispersant may be at least one of natural or synthetic clay minerals (e.g., kaolin, mica, magnesium aluminum garnet, clay, etc.), alumina, titanium dioxide, basic magnesium carbonate, basic zinc carbonate, calcium carbonate, silica, zinc borate, iron oxide, etc., and particularly preferably kaolin. Further, the dispersant may be used in an amount of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, and more preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of the nylon 6 particles.
The purpose of the addition of the dispersion enhancer is to improve the dispersion efficiency of the dispersant, i.e., to reduce the amount of the dispersant while retaining its function of preventing melt-bonding between particles. The dispersion enhancer may be any of various existing inorganic compounds having a solubility of 1mg in 100mL of water at 40 ℃ and providing a divalent or trivalent anion or cation. Examples of the dispersion-enhancing agent include, but are not limited to, at least one of magnesium nitride, magnesium nitrate, aluminum phosphate, magnesium sulfate, aluminum nitride, aluminum nitrate, aluminum sulfate, ferric chloride, ferric sulfate, ferric nitrate, and the like, preferably aluminum sulfate. The use of the dispersion-enhancing agent is advantageous for obtaining nylon 6 expanded beads having an apparent density of 100g/L or more. Further, the dispersion enhancer may be used in an amount of 0.0001 to 1 part by weight, preferably 0.01 to 0.2 part by weight, relative to 100 parts by weight of the nylon 6 particles.
The foaming agent can be an organic physical foaming agent or an inorganic physical foaming agent. Among them, examples of the organic type physical blowing agent include, but are not limited to, at least one of aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptane, alicyclic hydrocarbons such as cyclobutane and cyclohexane, and halogenated hydrocarbons such as chlorofluoromethane, trifluoromethane, 1, 2-difluoroethane, 1,2,2, 2-tetrafluoroethane, methyl chloride, ethyl chloride, methylene chloride, and the like. Examples of the inorganic type physical blowing agent include, but are not limited to, at least one of air, nitrogen, carbon dioxide, oxygen, and water. The blowing agent is preferably carbon dioxide and/or nitrogen, particularly preferably carbon dioxide, in view of stability (uniformity) of the apparent density of the nylon 6 expanded beads, low cost and environmental friendliness. In addition, the amount of the blowing agent to be used may be determined depending on the specific kind of the blowing agent, the foaming temperature, and the apparent density of the nylon 6 expanded beads to be produced. For example, when nitrogen is used as the blowing agent and water is used as the dispersion medium, the pressure in the closed vessel (i.e., the pressure (gauge pressure) in the upper space in the closed vessel) at the time of depressurization in the foaming apparatus is controlled to 1 to 12 MPa; when carbon dioxide is used as the blowing agent, the gauge pressure is controlled to 1 to 7 MPa. Generally, the desired pressure in the upper space in the closed vessel increases as the apparent density of the nylon 6 expanded beads to be obtained decreases.
The nylon 6 foamed bead prepared by the method has the advantages of low cost, compact pores, uniform pore size distribution and the like, and can be applied to occasions with higher requirements on light weight of plastic products, such as automobile parts, food and electronic packaging, architectural decoration and the like.
The nylon 6 base resin may further contain various conventional auxiliary agents which are generally used for nylon 6 expanded beads, for example, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a metal deactivator, a pigment, a nucleating agent, a filler, a stabilizer, a reinforcing agent, and the like. The types and the contents of the above-mentioned auxiliaries can be selected conventionally in the art, and those skilled in the art can know the types and the contents, and are not described herein again.
The third aspect of the invention provides a flame-retardant nylon 6 expanded bead molded body which is prepared from the flame-retardant nylon 6 expanded beads according to the second aspect of the invention through a molding process.
According to the flame-retardant nylon 6 expanded bead formed body of the present invention, the molding can be performed in various existing molding machines, and the molding conditions can be selected conventionally in the field, which can be known by those skilled in the art and will not be described herein.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention provides a halogen-free flame retardant, which comprises an inorganic flame retardant component and a long-acting antistatic agent (carbon nanofiber), wherein the two functional auxiliaries can play a synergistic effect, so that the flame retardant efficiency is effectively improved, the flame retardant effect is improved, the addition amount of the flame retardant is reduced, and the antistatic performance is not negatively influenced.
(2) The nylon 6 foaming bead provided by the invention has antistatic property and excellent flame retardant property, so that the nylon 6 foaming bead is suitable for the fields of mines, textile machinery, automobile and aviation equipment accessories, electronics, electricity, electric appliances and the like which have comprehensive requirements on flame retardant, antistatic and light weight. The preparation method of the nylon 6 composition material provided by the invention is simple and effective, and is easy to operate.
(3) The invention adopts carbon dioxide as the foaming agent, and has the advantages of environmental protection, safety and the like compared with the prior art which uses organic foaming agents.
(4) The flame-retardant nylon 6 expanded bead prepared by the method is of a non-crosslinked structure, can be recycled according to common nylon 6 modified materials, does not cause secondary pollution, and meets the requirement of circular economy.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings.
FIG. 1 shows a scanning electron micrograph of a cross section of the flame retardant nylon 6 expanded beads of example 1 of the present invention.
FIG. 2 shows a cross-sectional scanning electron micrograph of the conventional flame retardant nylon 6 expanded beads of comparative example 1 of the present invention.
Detailed Description
The invention will be described in further detail with reference to the following examples, but it should be noted that: the present invention is by no means limited to these examples.
The relevant data in the examples of the present invention were obtained according to the following test methods:
(1) density: measuring by a density gradient column method according to a method specified in GB/T1033.2-2010;
(2) limiting oxygen index test: the test was carried out according to the method described in the national Standard GB/T5454-1997;
(3) and (3) surface resistivity test: testing according to GB/T1410-2006;
(4) and (3) testing the compressive strength: the compression test was carried out according to ASTM Standard D3575-08 of the United states of America, and a compression test was carried out using a compression rate of 10mm/min, to obtain a compression strength at which the molded body was compressed by 50%.
Examples
The raw material ratios and reaction conditions of the flame retardant, the flame retardant nylon 6 composition, the expanded beads and other products prepared in this example are shown in tables 1 and 2, and table 2 also shows the performance parameters of the expanded beads. In the table, flame retardant component a is phosphine oxide, flame retardant component B is a transition metal salt, and flame retardant component C is an inorganic flame retardant component.
Example 1
Preparation of (I) flame retardant
Adding 7 parts by weight of triphenylphosphine oxide and 3 parts by weight of cobalt nitrate into ethanol, stirring at the speed of 100rpm, and heating the mixed material by using microwaves under stirring at the heating power of 50w and the temperature of 40 ℃ for 4 hours. Subjecting the material subjected to microwave heating reaction to supercritical drying to obtain complex Co (OPPh) formed by triphenylphosphine oxide and cobalt nitrate3)2(NO3)2。
The complex Co (OPPh) prepared above is added3)2(NO3)2Stirring with magnesium hydroxide mechanically to homogenizeAt 10rpm, a flame retardant was obtained.
Preparation of (di) carbon nano fiber antistatic agent
Coal pitch with carbon content of more than 80 mol% is used as a carbon source, and grinding pretreatment is carried out by using mixed acid of phosphoric acid/nitric acid/hydrochloric acid (volume ratio is 1:1:1) to obtain a pretreatment substance.
And adding the pretreated substance and a catalyst cobalt nitrate into a ball mill for mixing to obtain a compound.
And (3) carrying out carbonization reaction on the compound under the protection of high-purity nitrogen at 950 ℃, keeping the temperature for 1.5 hours, and then cooling to room temperature to obtain the self-assembled carbon nanofiber. After-treatment is not needed to remove the metallic impurities of the catalyst, and the cobalt content is 2.0wt percent through determination.
Preparation of (III) Nylon 6 base resin PA6-101
Nylon 6 resin.
Weighing 100 parts by weight of the nylon 6 resin, adding and then adding a lubricant (the adding amount of the lubricant is 0.1 part by weight based on 100 parts by weight of the nylon 6 resin), then adding the mixture into a high-speed stirrer for uniform mixing, then adding the mixed material into a feeder of a double-screw extruder manufactured by Nanjing Keplon company, feeding the material into a double screw through the feeder, keeping the temperature of the screw between 200 and 240 ℃ in the processing process, melting and uniformly mixing through the screw, then extruding, pelletizing and drying to obtain nylon 6 base resin granules PA 6-101.
(IV) preparation of flame retardant Nylon 6 composition
Weighing and mixing the components according to the ratio, wherein 100 parts by weight of the nylon 6 base resin PA6-101, 12 parts by weight of the flame retardant component, 1 part by weight of the carbon nanofiber antistatic agent and 0.3 part by weight of the 5000-mesh kaolin serving as the foam cell nucleating agent are used in the step (III). In addition, processing aids including antioxidant 1010(BASF corporation), antioxidant 168(BASF corporation) and the like are added in the preparation process of the composition, and the dosage is conventional dosage and is respectively 0.2 weight part and 0.1 weight part relative to 100 weight parts of nylon 6 base resin. And then adding the mixture into a high-speed stirrer for uniform mixing, adding the mixed material into a feeder of a double-screw extruder manufactured by Keplon, feeding the material into a double screw through the feeder, keeping the temperature of the screw between 200 ℃ and 240 ℃ in the processing process, melting and uniformly mixing the material by the screw, and feeding the material into a Lab100 microparticle preparation system, wherein the torque is controlled to be about 65 percent and the rotating speed is 300 rpm. To obtain the flame-retardant nylon 6 composition micro-particles.
Preparation method of (V) flame-retardant nylon 6 expanded beads
And (3) adding the flame-retardant nylon 6 composition microparticles obtained in the step (IV) and auxiliary agents such as dispersion medium deionized water, surfactant sodium dodecyl benzene sulfonate, dispersant kaolin, dispersion reinforcing agent aluminum sulfate and the like into an autoclave at one time, uniformly mixing, wherein the using amount of the dispersion medium is 2700 parts by weight, the using amount of the surfactant is 0.4 part by weight, the using amount of the dispersant is 5 parts by weight and the using amount of the dispersion reinforcing agent is 0.2 part by weight relative to 100 parts by weight of the flame-retardant nylon 6 composition.
The autoclave cover was closed tightly, residual air in the autoclave was purged with carbon dioxide, then carbon dioxide was continuously fed into the autoclave, heating was started and the pressure in the autoclave was preliminarily adjusted until it stabilized, and then the autoclave was stirred at a stirring speed of 100rmp to heat the temperature in the autoclave to 209 ℃ at a uniform speed.
The pressure in the autoclave was adjusted to 4MPa and the temperature was raised to 209.5 ℃ at an average heating rate of 0.1 ℃/min, followed by continuous stirring at the above pressure and temperature for 0.5 hour.
The discharge port of the autoclave was opened to discharge the contents of the autoclave into a collection tank to obtain expanded beads, and carbon dioxide gas was fed while discharging so that the pressure in the autoclave was maintained at about the foaming pressure before all the particles were completely foamed and entered the collection tank.
The beads were collected, dehydrated and dried, and nylon 6 expanded beads having a particle size of 2.8 to 3.35mm were sieved out using sieves having a pore diameter of 3.35mm and 2.8mm, and the electron micrographs of the cross sections thereof are shown in FIG. 1, respectively. As can be seen from the results of fig. 1, the nylon 6 expanded beads obtained from the nylon 6 composition provided by the present invention have dense and uniform cells.
(VI) preparation of flame-retardant Nylon 6 expanded bead molded article
And (3) performing molding forming on the flame-retardant nylon 6 expanded beads obtained in the step (five) by using a molding machine (Kurtz T-Line produced by Kurtz Ersa company, Germany, the same below) under the pressure of 0.71MPa, and curing the obtained molded body for 24 hours under the conditions that the temperature is 100 ℃ and the pressure is standard atmospheric pressure to obtain a molded product. Specific molding parameters such as the expanded bead fusion pressure and the steam pressure are shown in Table 2. The molded articles were used for testing the oxygen index, the char yield, the flame height, the smoke situation, the surface resistivity, and the compressive strength. The oxygen index test is carried out according to the method described in the national standard GB T2406.2-2009, and the surface resistivity test is carried out according to GB/T1410-. A50X 25mm sample was cut out from the expanded bead molded body, and a compression strength test was performed based on American ASTM standard D3575-08, and a compression test was performed at a compression rate of 10mm/min, to obtain a compression strength at which the molded body was compressed by 50%. The results of the above tests are shown in table 2.
Example 2
The preparation method of the flame retardant (i) and the preparation method of the carbon nanofiber antistatic agent (ii) were the same as in example 1 except for the raw material formulations and reaction conditions shown in tables 1 and 2. For example, the flame retardant formed in this example is Ni (OPOt) which is a complex of trioctylphosphine oxide and nickel nitrate3)2(NO3)2。
Preparation of (III) Nylon 6 base resin PA6-102
Nylon 6 resin.
Weighing 100 parts by weight of the nylon 6 resin, adding a lubricant (the adding amount of the lubricant is 0.1 part by weight based on 100 parts by weight of the nylon 6 resin), adding the mixture into a high-speed stirrer for uniform mixing, adding the mixed material into a feeder of a double-screw extruder manufactured by Nanjing Keplon company, feeding the material into a double screw through the feeder, keeping the temperature of the screw between 200 ℃ and 240 ℃ in the processing process, melting and uniformly mixing through the screw, extruding, granulating and drying to obtain nylon 6 base resin granules PA 6-102.
(IV) preparation of flame retardant Nylon 6 composition
The flame retardant nylon 6 composition was prepared as in example 1 except for the raw material ratios shown in Table 1. For example, the flame retardant component in this example was 14 parts by weight, the carbon nanofiber antistatic agent was 1.5 parts by weight, and the foam cell nucleating agent 2000 mesh talc was 0.06 parts by weight.
(V) preparation of flame-retardant nylon 6 foamed beads
And (3) adding the flame-retardant nylon 6 composition obtained in the step (IV) and auxiliary agents such as dispersion medium deionized water, surfactant sodium dodecyl benzene sulfonate, dispersant kaolin, dispersion reinforcing agent aluminum sulfate and the like into an autoclave at one time, and uniformly mixing, wherein the dosage of the dispersion medium is 3000 parts by weight, the dosage of the surfactant is 0.3 part by weight, the dosage of the dispersant is 4.5 parts by weight and the dosage of the dispersion reinforcing agent is 0.15 part by weight relative to 100 parts by weight of nylon 6 composition granules.
The autoclave cover was closed tightly, residual air in the autoclave was purged with carbon dioxide, then carbon dioxide was continuously fed into the autoclave, heating was started and the pressure in the autoclave was preliminarily adjusted until it stabilized, and then the autoclave was stirred at a stirring speed of 100rmp to heat the temperature in the autoclave to 208 ℃ at a uniform speed.
The pressure in the autoclave was adjusted to 5MPa and the temperature was raised to 208.5 c at an average heating rate of 0.1 c/min, followed by continuous stirring at the above pressure and temperature for 0.5 hour.
The discharge port of the autoclave was opened to discharge the contents of the autoclave into a collection tank to obtain expanded beads, and carbon dioxide gas was fed while discharging so that the pressure in the autoclave was maintained at about the foaming pressure before all the particles were completely foamed and entered the collection tank.
The beads were collected, dehydrated and dried, and nylon 6 expanded beads having a particle size of 2.8 to 3.35mm were sieved out using sieves having a pore size of 3.35mm and 2.8 mm.
(VI) preparation of Nylon 6 expanded bead molded article
And (5) carrying out molding forming on the nylon 6 expanded beads obtained in the step (five) by using a molding forming machine under the pressure of 0.73MPa, and curing the formed body for 24 hours under the conditions that the temperature is 100 ℃ and the pressure is standard atmospheric pressure to obtain a molded product. The oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength were measured and the results are shown in Table 2.
Example 3
The preparation method of the flame retardant (i) and the preparation method of the carbon nanofiber antistatic agent (ii) were the same as in example 1 except for the raw material formulations and reaction conditions shown in tables 1 and 2. For example, the flame retardant formed in this example is Co (OPOt) complex of trioctylphosphine oxide and cobalt nitrate3)2(NO3)2。
Preparation of (III) Nylon 6 base resin PA6-103
Nylon 6/PET alloy with a weight ratio of 8: 2.
Weighing 100 parts by weight of the nylon 6/PET alloy, adding a lubricant (the adding amount of the lubricant is 0.1 part by weight based on 100 parts by weight of the nylon 6/PET alloy), adding the mixture into a high-speed stirrer for uniform mixing, adding the mixed material into a feeder of a double-screw extruder manufactured by Nanjing Keplong company, feeding the material into a double screw through the feeder, keeping the temperature of the screw between 200 and 240 ℃ in the processing process, melting and uniformly mixing through the screw, extruding, granulating and drying to obtain nylon 6 base resin granules PA 6-103.
(IV) preparation of flame retardant Nylon 6 composition As in example 1
The flame retardant nylon 6 composition was prepared as in example 1 except for the raw material ratios shown in Table 1. For example, the flame retardant component in this example is 15.5 parts by weight, the carbon nanofiber antistatic agent is 1.5 parts by weight, and the cell nucleating agent 10000 mesh talc is 0.12 parts.
(V) preparation of flame-retardant nylon 6 foamed beads
And (3) adding the flame-retardant nylon 6 composition obtained in the step (IV) and auxiliary agents such as dispersion medium deionized water, surfactant sodium dodecyl benzene sulfonate, dispersant kaolin, dispersion reinforcing agent aluminum sulfate and the like into an autoclave at one time, and uniformly mixing, wherein the dosage of the dispersion medium is 3000 parts by weight, the dosage of the surfactant is 0.35 part by weight, the dosage of the dispersant is 4.8 parts by weight and the dosage of the dispersion reinforcing agent is 0.15 part by weight relative to 100 parts by weight of nylon 6 composition granules.
The autoclave was closed, the residual air in the autoclave was purged with carbon dioxide, and then carbon dioxide was continuously fed into the autoclave, heating was started and the pressure in the autoclave was preliminarily adjusted until it was stabilized, and then the autoclave was stirred at a stirring speed of 100rmp to heat the temperature in the autoclave to 208.5 ℃ at a uniform speed.
The pressure in the autoclave was adjusted to 5MPa and the temperature was raised to 209 ℃ at an average heating rate of 0.1 ℃/min, followed by continuous stirring at the above pressure and temperature for 0.5 hour.
The discharge port of the autoclave was opened to discharge the contents of the autoclave into a collection tank to obtain expanded beads, and carbon dioxide gas was fed while discharging so that the pressure in the autoclave was maintained at about the foaming pressure before all the particles were completely foamed and entered the collection tank.
The beads were collected, dehydrated and dried, and nylon 6 expanded beads having a particle size of 2.8 to 3.35mm were sieved out using sieves having a pore size of 3.35mm and 2.8 mm.
(VI) preparation of flame-retardant Nylon 6 expanded bead molded article
And (5) carrying out molding forming on the nylon 6 expanded beads obtained in the step (five) by using a molding forming machine under the pressure of 0.69MPa, and curing the obtained formed body for 24 hours under the conditions that the temperature is 100 ℃ and the pressure is standard atmospheric pressure to obtain a molded formed product. The oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength were measured and the results are shown in Table 2.
Example 4
A flame retardant, a nylon 6 base resin, a flame retardant nylon 6 composition, flame retardant nylon 6 expanded beads, and a flame retardant nylon 6 expanded bead molded body were prepared in the same manner as in example 1, except that a carbon nanofiber antistatic agent was not prepared and used. The results of the tests on the oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength of the obtained molded articles are shown in Table 2.
Example 5
The preparation methods of the flame retardant, the carbon nanofiber antistatic agent, the nylon 6 base resin, the flame retardant nylon 6 composition, the flame retardant nylon 6 expanded beads and the flame retardant nylon 6 expanded bead molded body were the same as in example 1, except that the antistatic agent was replaced with carbon black in an amount of 6 parts by weight and the experimental conditions in tables 1 and 2. The results of the tests on the oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength of the obtained molded articles are shown in Table 2.
Comparative example 1
The preparation methods of the flame retardant, the carbon nanofiber antistatic agent, the nylon 6 base resin, the flame retardant nylon 6 composition, the flame retardant nylon 6 expanded beads and the flame retardant nylon 6 expanded bead molded body were the same as in example 1, except that the flame retardant was replaced with red phosphorus in an amount of 20 parts by weight and the experimental conditions in tables 1 and 2. The results of the tests on the oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength of the obtained molded articles are shown in Table 2.
Comparative example 2
The flame retardant, the carbon nanofiber antistatic agent, the nylon 6 base resin, the flame retardant nylon 6 composition, the flame retardant nylon 6 expanded beads and the molded flame retardant nylon 6 expanded beads were prepared in the same manner as in example 2, except that only magnesium hydroxide was used instead of the flame retardant in an amount of 30 parts by weight and the experimental conditions in tables 1 and 2 were used. The results of the tests on the oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength of the obtained molded articles are shown in Table 2.
Comparative example 3
The preparation methods of the flame retardant, the carbon nanofiber antistatic agent, the nylon 6 base resin, the flame retardant nylon 6 composition, the flame retardant nylon 6 expanded beads and the flame retardant nylon 6 expanded bead molded body were the same as in example 3, except that the flame retardant was replaced with a composition of hexabromocyclododecane and antimony trioxide in an amount of 30 parts by weight and the experimental conditions in tables 1 and 2. The results of the tests on the oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength of the obtained molded articles are shown in Table 2.
Comparative example 4
The preparation methods of the flame retardant, the carbon nanofiber antistatic agent, the nylon 6 base resin, the flame retardant nylon 6 composition, the flame retardant nylon 6 expanded beads and the molded flame retardant nylon 6 expanded beads were the same as in example 1, except that the flame retardant contains no cobalt nitrate as the flame retardant component B and the experimental conditions shown in tables 1 and 2. The results of the tests on the oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength of the obtained molded articles are shown in Table 2.
Comparative example 5
The preparation methods of the flame retardant, the carbon nanofiber antistatic agent, the nylon 6 base resin, the flame retardant nylon 6 composition, the flame retardant nylon 6 expanded beads and the molded flame retardant nylon 6 expanded beads were the same as in example 1, except that the flame retardant component a, triphenylphosphine oxide, and the experimental conditions in tables 1 and 2 were not contained in the flame retardant. The results of the tests on the oxygen index, char yield, flame height, smoke condition, surface resistivity and compressive strength of the obtained molded articles are shown in Table 2.
As can be seen from examples 1-5, the PA6-101 to PA6-103 prepared by the invention have good foaming performance, and the flame retardant antistatic nylon 6 composition is prepared by taking the PA6-101 to PA6-103 as a base resin, adding an organic phosphorus complex and inorganic hydroxide compound flame retardant and taking nickel or cobalt-containing carbon nanofibers as an antistatic agent. Then, according to the tank type dipping foaming method provided by the invention, the foaming is adjustedThe conditions of bubble pressure, temperature and the like can obtain expanded beads with the density of 0.51-0.79g/L, when non-supercritical carbon dioxide is used as a foaming agent, the foaming effect is good, the cell density is high, the cells are compact and uniform, the cell size is small, the cell walls are thin, and the surfaces of the beads are smooth, wherein the sectional view of the beads of the example 1 is shown in the attached figure 1. The mechanical, flame-retardant and antistatic properties of the molded articles are shown in Table 2. Wherein, the good cell structure leads the compression performance of the formed body to be excellent; the oxygen index of the formed body and the related flame-retardant test conditions show that the flame retardant compound and the antistatic agent can exert synergistic effect, the addition amount of the flame retardant can be effectively reduced, the oxygen index is higher than 28, the formed body can be used in the field with higher requirement on flame-retardant level, and meanwhile, the surface resistivity reaches 109Omega antistatic grade.
It can be seen from examples 5 and 1 to 3 that, with the conventional antistatic agent carbon black, no synergistic effect is exhibited between the flame retardant and the carbon black, and therefore, both the flame retardant performance and the antistatic performance are lower than those of examples 1 to 3.
It can be seen from comparative examples 1 to 3 and table 2 that, when expanded beads are prepared from nylon 6 base resin obtained by compounding conventional red phosphorus, bromine-based flame retardants, magnesium hydroxide alone and nickel or cobalt-containing carbon nanofibers as a compounded flame-retardant antistatic agent, the flame-retardant ability and antistatic property of the molded article formed from the beads are inferior to those of the expanded beads obtained from the compositions of examples 1 to 3, and the addition of the flame retardants and antistatic agent in the comparative examples has a negative effect on the foaming properties, the cells are not uniform, and the cell walls are broken. Comparing examples 1-3 with comparative examples 4-5, it can be seen that in the antistatic system composed of the complex formed by organic phosphorus and transition metal such as nickel cobalt, and magnesium hydroxide or aluminum hydroxide as the flame retardant and the carbon nanofibers, the transition metal and magnesium hydroxide generate a concerted catalysis effect, and the flame retardant efficiency of the phosphorus flame retardant is improved. The carbon nanofibers can construct an effective conductive network in the resin, so that a long-acting antistatic network system is formed, and the surface resistivity of the foamed bead forming body is effectively reduced. The nickel or cobalt catalyst remained in the carbon fiber can form good synergistic effect with the chelate, and the flame retardant efficiency is improved. In addition, in comparative example 1, the composition obtained by using the system formed by the conventional red phosphorus flame retardant and the antistatic agent had no synergistic effect, but rather, the flame retardant and the antistatic property were lowered by the mutual influence, and the cell structure of the beads was negatively affected, and the obtained expanded beads had a low cell density, a large cell diameter, and a phenomenon in which cell wall breakage occurred (as shown in FIG. 2).
Claims (25)
1. A flame retardant nylon 6 foamed composition comprising: the flame retardant comprises nylon 6 base resin, a flame retardant, a carbon nanofiber antistatic agent and an antioxidant, wherein the flame retardant comprises a complex formed by phosphine oxide and a transition metal salt; the transition metal salt comprises a transition metal organic salt and/or a transition metal inorganic salt; the transition metal is a VIII group metal element;
the flame retardant is in an amount of 5 to 50 parts by weight and the carbon nanofiber antistatic agent is in an amount of 0.1 to 10 parts by weight, based on 100 parts by weight of the nylon 6 base resin; the amount of the antioxidant is 0.1 to 0.5 weight part;
the flame retardant comprises 1-10 parts by weight of phosphine oxide and 3-15 parts by weight of transition metal salt.
2. The flame retardant nylon 6 foam composition of claim 1, wherein the nylon 6 base resin comprises nylon 6 or a mixture of nylon 6 and other resins.
3. The flame retardant nylon 6 foam composition of claim 2, wherein the other resin comprises one or more of high density polyethylene, low density polyethylene, polypropylene, styrene-ethylene-butylene-styrene block copolymer, polyester, and thermoplastic polyurethane.
4. The flame retardant nylon 6 foam composition of claim 1, wherein the phosphine oxide has the following structural formula I:
wherein R is1、R2And R3Are the same or different and are each independently selected from C1-C18Straight chain alkyl, C3-C18Branched alkyl radical, C1-C18Straight-chain alkoxy radical, C3-C18Branched alkoxy, C6-C20Substituted or unsubstituted aromatic group and C6-C20Substituted or unsubstituted aryloxy.
5. The flame retardant nylon 6 foam composition of claim 4, wherein R is R1、R2And R3Each independently selected from C4-C18Straight or branched chain alkyl and C having 1 or 2 carbon rings6-C18An aromatic group.
6. The flame retardant nylon 6 foam composition of claim 4, wherein R in formula I is1、R2And R3Each independently selected from C having a main carbon chain of 6 or more carbon atoms6-C12Straight or branched chain alkyl and substituted or unsubstituted phenyl.
7. The flame retardant nylon 6 foam composition of claim 4, wherein in formula I, the phosphine oxide is at least one selected from the group consisting of triphenylphosphine oxide, bis (4-hydroxyphenyl) phenylphosphine oxide, bis (4-carboxyphenyl) phenylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, tridecylphosphine oxide, tributyl phosphate and dibutyl butylphosphate.
8. The flame retardant nylon 6 foam composition of any of claims 1-7, wherein the transition metal salt is selected from at least one of a nitrate, thiocyanate, formate, acetate and oxalate salt of a transition metal.
9. The flame retardant nylon 6 foam composition of any of claims 1-7, wherein the transition metal is cobalt and/or nickel.
10. The flame retardant nylon 6 foam composition according to any one of claims 1 to 7, wherein the preparation of the complex comprises: stirring and mixing 1-10 parts by weight of phosphine oxide and 3-15 parts by weight of transition metal salt in an organic solvent, then carrying out microwave heating and supercritical drying to obtain the complex.
11. The flame retardant nylon 6 foam composition of claim 10, wherein the organic solvent is at least one of ethanol, acetone, pyridine, tetrahydrofuran and DMF.
12. The flame retardant nylon 6 foam composition according to any one of claims 1 to 7, wherein the amount of the flame retardant is 10 to 20 parts by weight based on 100 parts by weight of the nylon 6 base resin.
13. The flame retardant nylon 6 foamed composition according to any one of claims 1 to 7, further comprising an inorganic flame retardant component; and/or
The weight ratio of the complex in the flame retardant to the inorganic flame retardant component is (1-5): 1.
14. The flame retardant nylon 6 foam composition of claim 13, wherein the inorganic flame retardant component is selected from group IIA and IIIA metal hydroxides.
15. The flame retardant nylon 6 foam composition of claim 13, wherein the inorganic flame retardant component is selected from magnesium hydroxide and/or aluminum hydroxide.
16. The flame retardant nylon 6 foam composition according to any one of claims 1 to 7, wherein the carbon nanofiber antistatic agent contains 1 to 5 wt% of transition metal based on 100 parts by weight of the nylon 6 base resin.
17. The flame retardant nylon 6 foam composition of claim 16, wherein the amount of the carbon nanofiber antistatic agent is 1 to 3 parts by weight based on 100 parts by weight of the nylon 6 base resin.
18. The flame retardant nylon 6 foam composition of claim 16, wherein the carbon nanofiber antistatic agent is prepared by a method comprising:
the carbon source is treated by acid, then forms a compound with a transition metal catalyst, and the compound is carbonized at the temperature of 800-1200 ℃ under the protection of inert gas.
19. The flame retardant nylon 6 foam composition of claim 18, wherein the carbon source is at least one selected from carbon pitch, petroleum pitch, coal tar, natural graphite, artificial graphite, bamboo charcoal, carbon black, activated carbon and graphene.
20. The flame retardant nylon 6 foaming composition as claimed in claim 18, wherein the carbon source is at least one selected from coal pitch, petroleum pitch and bamboo charcoal with carbon content of 80 wt% or more.
21. The flame retardant nylon 6 foam composition of claim 18, wherein the transition metal catalyst is selected from at least one of a chloride, sulfate, nitrate, acetate, and cyclopentadienyl compound of a transition metal; and/or
The mass ratio of the transition metal catalyst to the carbon source in terms of transition metal is (35-70): 100.
22. The flame retardant nylon 6 foam composition of claim 18, wherein the transition metal is selected from at least one of iron, cobalt, nickel and chromium.
23. A flame retardant nylon 6 expanded bead prepared by subjecting a material comprising 100 parts by weight of the flame retardant nylon 6 composition of any one of claims 1 to 22 and 0.001 to 5 parts by weight of a cell nucleating agent to a dip foaming process.
24. The flame retardant nylon 6 expanded bead according to claim 23, wherein the foam cell nucleating agent is 0.05 to 1.5 parts by weight.
25. A flame-retardant nylon 6 molded body prepared from the flame-retardant nylon 6 expanded beads according to claim 24 through a molding process.
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| CN107057300A (en) * | 2017-04-25 | 2017-08-18 | 中国科学院宁波材料技术与工程研究所 | A kind of high polymer material of halogen-free flame retardants and the application halogen-free flame retardants |
| CN107189427A (en) * | 2017-06-24 | 2017-09-22 | 镇江严彦气体有限公司 | A kind of flame retardant compositions |
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