阅读说明：本技术 一种阻燃稳定剂、无卤阻燃玻纤增强聚丙烯及其制法 (Flame-retardant stabilizer, halogen-free flame-retardant glass fiber reinforced polypropylene and preparation method thereof ) 是由 胡爽 肖雄 许肖丽 叶文 董玲玲 林倬仕 李平阳 尹亮 于 2019-09-02 设计创作，主要内容包括：本发明涉及一种阻燃稳定剂、无卤阻燃玻纤增强聚丙烯组合物及其制法,包含以下重量份组分：组分A：焦磷酸哌嗪或其聚合物0.1-30份,组分B：增效剂或阻燃剂0.1-50份,组分C：促成炭剂0-70份,组分D：涂覆物0-20份,组分E：抗氧剂0-10份,组分F：稳定剂0-10份。与现有技术相比,本发明的阻燃稳定剂除阻燃性以外,还在聚丙烯上产生稳定化的效果,以及含有这样的阻燃稳定剂的无卤阻燃玻纤增强聚丙烯组合物成型料,通过“三位一体”阻燃剂,按照合适的P、N比例进行酸源及气源的补充,并添加其他辅助的稳定剂、抗氧剂、金属氧化物和/或金属氢氧化物等,达到本发明的目的。(The invention relates to a flame retardant stabilizer, a halogen-free flame retardant glass fiber reinforced polypropylene composition and a preparation method thereof, wherein the flame retardant stabilizer comprises the following components in parts by weight: and (2) component A: 0.1-30 parts of piperazine pyrophosphate or a polymer thereof, and a component B: 0.1-50 parts of synergist or flame retardant, and component C: 0-70 parts of a char-forming promoter, and a component D: 0-20 parts of coating, component E: 0-10 parts of antioxidant, and a component F: 0-10 parts of a stabilizer. Compared with the prior art, the flame retardant stabilizer has a stabilizing effect on polypropylene besides flame retardance, and the halogen-free flame retardant glass fiber reinforced polypropylene composition molding material containing the flame retardant stabilizer supplements an acid source and a gas source according to a proper P, N proportion through a 'three-in-one' flame retardant, and is added with other auxiliary stabilizers, antioxidants, metal oxides and/or metal hydroxides and the like, so that the purpose of the flame retardant stabilizer is achieved.)

1. The flame retardant stabilizer is characterized by comprising the following components in parts by weight:

and (2) component A: 0.1 to 30 portions of pyrophosphoric piperazine and/or polymer thereof,

and (B) component: 0.1 to 50 portions of synergist or flame retardant,

and (3) component C: 0-70 parts of a char-forming promoter,

and (3) component D: 0-20 parts of a coating material,

and (3) component E: 0-10 parts of an antioxidant, namely,

and (3) component F: 0-10 parts of a stabilizer.

2. The flame retardant stabilizer according to claim 1, characterized by comprising the following components in parts by weight:

and (2) component A: 0.1 to 30 portions of pyrophosphoric piperazine and/or polymer thereof,

and (B) component: 0.1 to 40 portions of synergist or flame retardant,

and (3) component C: 0.1 to 50 portions of charring accelerator,

and (3) component D: 0.1 to 15 portions of coating materials,

and (3) component E: 0.1 to 5 portions of antioxidant,

and (3) component F: 0.1-5 parts of a stabilizer.

3. A flame retardant stabilizer according to claim 1 or 2, wherein said piperazine pyrophosphate and/or its polymer has a molecular structure of:

wherein n is 10-30.

4. A flame retardant stabilizer according to claim 1 or 2, characterized in that said piperazine pyrophosphate and/or its polymer has a degree of polymerization > 15; d₅₀＜30μm，D₉₀＜50μm。

5. A flame retardant stabilizer according to claim 1 or 2, wherein said synergist or flame retardant comprises one or more of melamine condensation products, reaction products of melamine and polyphosphoric acid, reaction products of melamine condensation products and polyphosphoric acid, melamine pyrophosphate, condensation products of melamine and cyanuric acid, or melam polyphosphate.

6. A flame retardant stabilizer according to claim 1 or 2, wherein said synergist or flame retardant comprises compounds represented by formulae 1 to 4 or mixtures thereof:

wherein: r₁-R₃Represents one or more of the following groups: hydrogen; c₁-C₈Alkyl radical, C₅-C₁₀CycloalkanesBase, C₅-C₁₀Alkylcycloalkyl radicals or their hydroxy functions or C₁-C₄A substituent of a hydroxyalkyl functional group; c₂-C₈Alkoxy radical, C₁-C₈Acyloxy, C₆-C₁₂An aryl group; n-alicyclic, N-aromatic;

R₄-R₆represents one or more of the following groups: c₁-C₈Alkyl radical, C₅-C₁₀Cycloalkyl radicals their hydroxy function or C₁-C₄A hydroxyalkyl functional substituent; c₂-C₈Alkoxy radical, C₁-C₈Acyloxy, C₆-C₁₂An aryl group;

R₇-R₁₀and R₄The groups are the same;

n represents the degree of polymerization, m and n independently of one another represent 1, 2, 3 or 4;

x represents an acid or an adduct with a triazine compound.

7. A flame retardant stabilizer according to claim 1 or 2, wherein said char-forming promoter is a phosphorus-containing char-forming promoter, having a degree of polymerization > 1000; the whiteness is more than 99; the 1% thermal decomposition temperature is more than 280 ℃;

the coating comprises one or more of metal oxide, metal hydroxide and metal salt;

the antioxidant comprises one or more of 2, 6-di-tert-butyl-p-cresol, beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid octadecyl ester, 1, 3-tri (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 2' -methylene bis (4-ethyl-6-tert-butylphenol), 1,3, 5-tri (3, 5-tert-butyl-4-hydroxybenzyl) trimethylbenzene, 2' -methylene bis (4-methyl-6-tert-butylphenol), 1, 6-hexamethylene bis (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate or 4,4' -di-tert-octyldiphenylamine;

the stabilizer comprises one or more of phenyl o-hydroxybenzoate, 2- (2 '-hydroxy-5' -methylphenyl) benzotriazole, 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2- (2 '-hydroxy-3', 5 '-di-tert-phenyl) -5-chlorobenzotriazole or 2,2' -thiobis (4-tert-octylphenoxy) nickel.

8. A flame retardant stabilizer according to claim 7 wherein said char former comprises one or more of ammonium phosphate, ammonium sulfate, ammonium polyphosphate, urea phosphate, amine polyphosphate, triphenyl phosphate, or aryl phosphate;

the metal oxide comprises magnesium oxide, calcium oxide, zinc oxide, manganese oxide and tin oxide;

the metal hydroxide comprises magnesium hydroxide, aluminum hydroxide, zinc hydroxide, calcium hydroxide and manganese hydroxide;

the metal salt comprises zinc phosphate, zinc molybdate, zinc sulfate, zinc stearate, basic zinc silicate, zinc stannate, magnesium phosphate and calcium phosphate;

the antioxidant comprises any one or a combination of a plurality of 2,2 '-methylene bis (4-ethyl-6-tert-butylphenol), 1,3, 5-tris- (3, 5-tert-butyl-4-hydroxybenzyl) -trimethylbenzene and 2,2' -methylene bis (4-methyl-6-tert-butylphenol);

the stabilizer comprises one or a combination of more of phenyl o-hydroxybenzoate, 2- (2' -hydroxy-5 ' -methylphenyl) benzotriazole, 2-hydroxy-4-n-octoxy benzophenone and 2,2' -thiobis (4-tert-octylphenoxy) nickel.

9. The halogen-free flame-retardant glass fiber reinforced polypropylene composition containing the flame-retardant stabilizer of claim 1, which is characterized by comprising the following components in parts by weight: 0.1-30 parts of glass fiber, 40-100 parts of polypropylene and 0.1-30 parts of flame retardant stabilizer.

10. The halogen-free flame-retardant glass fiber reinforced polypropylene composition as claimed in claim 9, wherein the polypropylene comprises a thermoplastic polypropylene of homo polypropylene, random copolymer polypropylene or block copolymer polypropylene;

the diameter of the glass fiber is 8-15 μm, and the surface of the glass fiber is impregnated by silane or titanate coupling agent.

11. The preparation method of the halogen-free flame-retardant glass fiber reinforced polypropylene composition according to claim 9, comprising the following steps:

(1) mixing the component A, the component B, the component C, the component D, the component E and the component F in a mixer according to the parts by weight to obtain a flame-retardant stabilizer;

(2) adding polypropylene into the composition obtained in the step (1), and mixing at a high speed to obtain a uniform mixture;

(3) and (3) placing the mixture obtained in the step (2) in a feeding port of an extruder, introducing glass fiber at an opening of a glass fiber port, vacuumizing the extruder, and extruding the materials to obtain the halogen-free flame-retardant glass fiber reinforced polypropylene composition.

12. The method for preparing the halogen-free flame-retardant glass fiber reinforced polypropylene composition according to claim 11, wherein the mixer is a cross-shaft double-cone co-directional double-motion mixer, and the internal structure is a full-size blade set;

in the step (1), the rotating speed of a mixer body is 20-40rpm, the rotating speed of internal blades is 30-50rpm, the inclination angle of the mixer body is 0-30 degrees, and the mixing time is 5-10 min;

in the step (2), the rotating speed of the body of the mixer is 30-50rpm, the rotating speed of the internal blades is 30-60rpm, the inclination angle of the body is 0-30 degrees, and the mixing time is 5-10 min;

the vacuumizing operation in the step (3) enables the vacuum pressure in the extruder to be 0.03-0.06 MPa; the double-screw extruder is a 20-type co-rotating double-screw extruder and comprises a melting section, a conveying section, a mixing section, a homogenizing section and a metering section which are sequentially arranged; wherein the temperature from the melting section to the metering section is as follows: at 200 ℃ at 180 ℃, at 220 ℃ at 200 ℃ at 230 ℃; the main machine rotating speed of the double-screw extruder is 200-400 rpm; the feeding frequency is 10-20 Hz.

13. The method for preparing the halogen-free flame-retardant glass fiber reinforced polypropylene composition as claimed in claim 12, wherein the melting section of the twin-screw extruder is provided with a small-lead conveying screw, the conveying section is provided with a large-lead conveying screw, the mixing section is provided with a structure in which 45 °, 60 ° and 90 ° shearing screws are sequentially stacked, the homogenizing section is provided with a structure in which 45 ° or 60 ° shearing screws and small-lead conveying screws are stacked, and the metering section is provided with a structure in which a large-lead conveying screw and a reverse screw are stacked.

A vacuum port is arranged between the mixing section and the homogenizing section, and the vacuum port is used for vacuumizing.

Technical Field

The invention relates to the technical field of flame-retardant materials, in particular to a flame-retardant stabilizer, a halogen-free flame-retardant glass fiber reinforced polypropylene composition containing the flame retardant and a preparation method of the composition.

Background

The processing of thermoplastic polypropylene is carried out as a melt, except in a few cases. Polypropylene can hardly undergo the structural and state changes associated therewith, without undergoing changes in its chemical structure. The result may be a series of irreversible changes, such as oxidation, crosslinking, molecular weight changes, etc., which in turn may cause a certain reduction in the physical and technical properties of the material, which would be detrimental to the use of the material. To reduce the reaction of this process, it is generally permissible to add adjuvants during processing. Typically stabilizers or combinations thereof, which are effective in reducing degradation and crosslinking reactions during melt processing.

By using different additives simultaneously. Such as antioxidants and stabilizers, whereby the polypropylene is not chemically degraded during processing and can withstand longer external influences.

Although one of the important general-purpose polypropylenes, the polypropylene material still has many defects, such as poor dimensional stability, low heat distortion temperature, poor low-temperature impact strength, easy spontaneous combustion and the like. Based on these drawbacks, the main solution adopted today is to make reinforced modifications to the material. Commonly used reinforcing materials include Glass Fibers (GF), carbon fibers and whiskers, etc., wherein carbon fibers and whiskers have a high reinforcing effect, but the preparation cost is high, and the industrial preparation has great difficulty. Glass fibers are widely used for material reinforcement due to their low price, good material compatibility and relatively simple preparation process. The introduction of the glass fiber obviously improves the dimensional stability, thermal deformation temperature, impact resistance, chemical solvent resistance, aging resistance and moisture absorption resistance of the polypropylene material. Therefore, the application range of the glass fiber reinforced polypropylene is wider, especially in the situation that certain environments need to work. However, glass fiber reinforced polypropylene is more difficult to flame retard than pure polypropylene, primarily due to the "wick effect". By "wick effect" is meant that after glass fibers are added to the material, the glass fibers create an effect in the material similar to a candle wick in a candle, making the material more susceptible to dripping and burning after ignition, and not self-extinguishing. The candlewick effect limits the application of glass fiber reinforced materials in industries of automobiles, electronic appliances and the like, in particular to automotive interior parts, power sockets, switch assemblies, connectors, electric appliance shells and the like. In the past decades, halogen flame retardants have occupied a large portion of the flame retardant market, especially in glass fiber reinforced materials, and are widely used. However, halogen flame retardants can corrode equipment during the early preparation of flame retardant materials; halogen flame retardants can generate corrosive and toxic gases (especially "dioxins") during the combustion of materials. With the enhancement of social environmental awareness and the issuance of various environmental regulations, the flame retardant materials tend to be non-halogenated.

For glass fiber reinforced polypropylene materials, the conventional halogen-free flame retardants for such polypropylene are typically red phosphorus, hydroxide, or triazine char-forming systems. Although red phosphorus has a good flame retardant effect, the red phosphorus has extremely strong colorability, and the application of the red phosphorus is greatly limited. The hydroxide is generally added in an amount of 50 to 60% by weight, which greatly deteriorates the properties of the material. The triazine charring agent system is generally widely used in unreinforced polypropylene materials, and the charring performance of the triazine charring agent system is enabled to be invalid to a great extent due to the candle core effect of glass fibers in the reinforced polypropylene, so that the flame retardant effect is influenced. The invention discloses a macromolecular triazine charring agent and a preparation method thereof (CN20120209288.4), which relates to a preparation method of a triazine charring agent, wherein a triazine charring agent with a novel structure is synthesized, but chlorine-containing toxic waste liquid is inevitably generated from cyanuric chloride, and the reaction process is complex because post-treatment is required. In recent years, no better flame retardant system exists for flame retardance of glass fiber reinforced polypropylene, particularly for polypropylene with high glass fiber content.

Chinese patent CN106366443 discloses a long glass fiber reinforced polypropylene material, a preparation method and an application thereof, which are mainly prepared from the following raw materials: 20-70 parts of polypropylene resin; 20-50 parts of continuous glass fiber; 3-10 parts of a glass fiber compatilizer; 0.5-5 parts of a flame retardant; 0.2-0.5 part of stabilizer; 0.2-0.5 part of heat stabilizer; 0.1-0.2 part of lubricant; 1-3 parts of color master batch. The flame retardant used in the invention patent is a brominated flame retardant and hydroxide, and limits the application of the glass fiber reinforced material in the field with strict requirements on non-halogenation.

The combination of novel comprehensive flame retardant and stabilizer is actively searched, which has great significance for glass fiber reinforced polypropylene materials and a plurality of fields with flame retardant requirements, and people are actively exploring the research and development of the flame retardant.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a flame retardant stabilizer, a halogen-free flame retardant glass fiber reinforced polypropylene composition and a preparation method thereof, wherein the flame retardant stabilizer, the halogen-free flame retardant glass fiber reinforced polypropylene composition and the preparation method thereof achieve the aim of the invention by using a 'three-in-one' flame retardant, supplementing an acid source and a gas source according to a proper P, N proportion and adding other auxiliary stabilizers, antioxidants, metal oxides and/or metal hydroxides and the like to produce a stabilization effect on polypropylene and a glass fiber reinforced polypropylene molding material containing the flame retardant-stabilizer-composition.

The purpose of the invention can be realized by the following technical scheme:

a flame retardant stabilizer comprises the following components in parts by weight:

and (2) component A: piperazine pyrophosphate or a polymer thereof 0.1 to 30 parts, preferably 0.1 to 30 parts,

and (B) component: 0.1 to 50 parts of synergist or flame retardant, preferably 0.1 to 40 parts,

and (3) component C: 0.1 to 70 parts of carbon forming promoter, preferably 0.1 to 50 parts,

and (3) component D: 0 to 20 parts, preferably 0.1 to 15 parts,

and (3) component E: 0 to 10 parts of antioxidant, preferably 0.1 to 5 parts,

and (3) component F: 0 to 10 parts of stabilizer, preferably 0.1 to 5 parts,

preferably, the molecular structure of the piperazine pyrophosphate and/or the polymer thereof is as follows:

wherein n is 10-30.

More preferably, the degree of polymerization of said pyrophosphate piperazine or its polymer is > 15, D₅₀＜30μm， D₉₀Less than 50 μm of piperazine phosphate focus.

Piperazine pyrophosphate (poly) phosphate was synthesized by the prior art (method disclosed in patent publication No. CN102304100A), and was prepared by the following synthetic route:

(1) introducing nitrogen into a reactor for 0.5-1 hour, evacuating the internal air, then weighing phosphoric acid and piperazine phosphate (the molar ratio is n phosphoric acid: n piperazine phosphate is 1:1), adding into the reactor, heating in a water bath to 80-100 ℃, continuously introducing nitrogen for protection, starting stirring, wherein the stirring speed is 40-60rpm, the reaction time is 2-3 hours, cooling to room temperature after complete reaction, filtering, drying and crushing to obtain a white intermediate product, namely piperazine diphosphate;

(2) weighing piperazine diphosphate and phosphoric acid (the molar ratio is that the piperazine diphosphate to the n-phosphoric acid is 1:1), adding the piperazine diphosphate and the phosphoric acid into a reactor, heating the mixture in an oil bath to 180-.

Preferably, the synergist or flame retardant comprises one or more of a melamine condensation product, a reaction product of melamine and polyphosphoric acid, a reaction product of a condensation product of melamine and polyphosphoric acid, melamine pyrophosphate, a condensation product of melamine and cyanuric acid, or melam polyphosphate.

Preferably, the synergist or flame retardant comprises a compound represented by formulae 1-4 or a mixture thereof:

wherein: r₁-R₃Represents one or more of the following groups: hydrogen; c₁-C₈Alkyl radical, C₅-C₁₀Cycloalkyl radical, C₅-C₁₀Alkylcycloalkyl radicals or their hydroxy functions or C₁-C₄A substituent of a hydroxyalkyl functional group; c₂-C₈Alkoxy radical, C₁-C₈Acyloxy, C₆-C₁₂An aryl group; n-alicyclic, N-aromatic;

R₄-R₆represents one or more of the following groups: c₁-C₈Alkyl radical, C₅-C₁₀Cycloalkyl radicals their hydroxy function or C₁-C₄A hydroxyalkyl functional substituent; c₂-C₈Alkoxy radical, C₁-C₈Acyloxy, C₆-C₁₂An aryl group; r₇-R₁₀And R₄The groups are the same;

n represents the degree of polymerization, m and n independently of one another represent 1, 2, 3 or 4;

x represents an acid or an adduct with a triazine compound.

Further preferably, the synergist or the flame retardant is one or a mixture of several of the structures shown in formula 2 or formula 3.

Particularly preferably, the synergist or the flame retardant is one of melamine polyphosphate and melamine cyanurate with the thermal decomposition temperature of 1 percent being more than 280 ℃.

Preferably, the char-forming agent comprises one or more of ammonium phosphate, ammonium sulfate, ammonium polyphosphate, urea phosphate, amine polyphosphate, triphenyl phosphate, or aryl phosphate.

Further preferably, the degree of polymerization of the char-forming promoter is > 1000; the whiteness is more than 99; ammonium polyphosphate with a 1% thermal decomposition temperature of more than 280 ℃.

Preferably, the coating comprises one or more of metal oxide, metal hydroxide and metal salt; there are two roles of metal coating: one is a synergist used as a flame retardant, and can play a synergistic flame retardant role in a condensed phase and a gas phase at the same time; the second one can be used as an alkaline substance to neutralize the acidity of the flame retardant and reduce the influence of the flame retardant stabilizer system on the material performance in the material processing process.

Further preferably, the metal oxide includes magnesium oxide, calcium oxide, zinc oxide, manganese oxide, tin oxide; the metal hydroxide comprises magnesium hydroxide, aluminum hydroxide, zinc hydroxide, calcium hydroxide and manganese hydroxide; the metal salt comprises zinc phosphate, zinc molybdate, zinc sulfate, zinc stearate, basic zinc silicate, zinc stannate, magnesium phosphate and calcium phosphate.

Preferably, the antioxidant comprises 2, 6-di-tert-butyl-p-cresol, octadecyl beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, 1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 2' -methylenebis (4-ethyl-6-tert-butylphenol), 1,3, 5-tri (3, 5-tertiary butyl-4-hydroxybenzyl) trimethylbenzene, 2 '-methylene bis (4-methyl-6-tertiary butyl phenol), 1, 6-hexamethylene bis (3, 5-di-tertiary butyl-4-hydroxyphenyl) propionate or 4,4' -di-tertiary octyl diphenylamine.

Further preferably, the antioxidant is any one or combination of several of 2,2 '-methylene bis (4-ethyl-6-tert-butylphenol), 1,3, 5-tris- (3, 5-tert-butyl-4-hydroxybenzyl) -trimethylbenzene and 2,2' -methylene bis (4-methyl-6-tert-butylphenol).

Preferably, the stabilizer comprises one or more of phenyl ortho-hydroxybenzoate, 2- (2 '-hydroxy-5' -methylphenyl) benzotriazole, 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2- (2 '-hydroxy-3', 5 '-di-tert-phenyl) -5-chlorobenzotriazole or 2,2' -thiobis (4-tert-octylphenoxy) nickel.

Further preferably, the stabilizer is any one or a combination of several of phenyl ortho-hydroxybenzoate, 2- (2' -hydroxy-5 ' -methylphenyl) benzotriazole, 2-hydroxy-4-n-octoxy benzophenone, and 2,2' -thiobis (4-tert-octylphenoxy) nickel.

A halogen-free flame-retardant glass fiber reinforced polypropylene composition containing a flame-retardant stabilizer comprises the following components in parts by weight: 0.1-30 parts of glass fiber, 40-100 parts of polypropylene and 0.1-30 parts of flame retardant stabilizer.

Preferably, the polypropylene comprises thermoplastic polypropylene of homo polypropylene, random copolymer polypropylene or block copolymer polypropylene; the diameter of the glass fiber is 8-15 μm, and the surface of the glass fiber is impregnated by silane or titanate coupling agent.

A preparation method of a halogen-free flame-retardant glass fiber reinforced polypropylene composition containing a flame-retardant stabilizer comprises the following steps:

(1) mixing the component A, the component B, the component C, the component D, the component E and the component F in a mixer according to the parts by weight to obtain a flame retardant-stabilizer composition;

(2) adding polypropylene into the composition, and then mixing at high speed in a mixer to obtain a uniform mixture;

(3) placing the mixture in a feeding port of an extruder, introducing glass fiber at an opening of a glass fiber port, vacuumizing the extruder, and extruding the materials to obtain glass fiber reinforced polypropylene;

(4) and (3) drying the glass fiber reinforced polypropylene, placing the glass fiber reinforced polypropylene in an injection molding machine, and performing injection molding to obtain a standard sample strip test.

Further, the rotating speed of the machine body of the mixer in the step (1) is 20-40rpm, the rotating speed of the internal blades is 30-50rpm, the inclination angle of the machine body is 0-30 degrees, and the mixing time is 5-10 min.

Further, the rotating speed of the machine body of the mixer in the step (2) is 30-50rpm, the rotating speed of the internal blades is 30-60rpm, the inclination angle of the machine body is 0-30 degrees, and the mixing time is 5-10 min.

Preferably, the polypropylene in step (2) includes a thermoplastic polypropylene of homo polypropylene, random copolymer polypropylene or block copolymer polypropylene.

More preferably, the polypropylene is one of random copolymer polypropylene and thermoplastic polypropylene of block copolymer polypropylene.

Preferably, the diameter of the glass fiber in the step (3) is 8-15 μm, and the surface is impregnated with silane or titanate coupling agent.

Further, in the step (3), the vacuum pressure is 0.03-0.06MPa, the main machine rotation speed of the extruder is 200-400rpm, the feeding frequency is 10-20Hz, and the temperatures of the melting section, the conveying section, the mixing section, the homogenizing section and the metering section of the extruder are as follows in sequence: at 200 ℃ at 180 ℃, at 220 ℃ at 200 ℃ at 230 ℃.

Further, the drying temperature in the step (4) is 60-100 ℃, the drying time is 3-6h, and the temperatures of the melting section, the conveying section and the metering section of the injection molding machine are 200-.

The glass fiber reinforced polypropylene is prepared by a cross rotating shaft double-cone double-motion mixer which adopts a same-direction double-motion mixer, a full-size blade group is arranged inside the mixer, the rotating speed range of a machine body is 10-40rpm, the rotating speed range of internal blades is 20-50rpm, and the inclination angle range of the machine body is 0-30 degrees.

Simultaneously, a 20-type co-rotating double-screw extruder is provided, and the screw structure is as follows: the melting section adopts a small-lead conveying thread, the conveying section adopts a small-lead conveying thread, the mixing section adopts 60-degree, 60-degree and 90-degree shearing threads for superposition, the homogenizing section adopts 30-degree or 45-degree or 60-degree shearing threads and small-lead conveying threads for superposition, and the metering section adopts a large-lead conveying thread and a reverse thread for superposition; the vacuum port is positioned between the mixing section and the homogenizing section, and the glass fiber port is positioned between the conveying section and the mixing section.

The application field of the material comprises one or more of an electric appliance shell, a capacitor, a switch, an instrument seat or a shell for a vehicle.

Piperazine pyrophosphate is an inorganic polymer, has remarkable thermal stability and self-charring performance, and is a new generation of charring agent. Meanwhile, an acid source, a carbon source and an air source are also arranged in the molecular structure, so that the flame retardant is a three-in-one flame retardant. The piperazine pyrophosphate has better self-charring performance under the conditions of nitrogen and air. Under the condition that a large amount of ammonium polyphosphate is not needed to promote the carbonization, a large amount of expanded carbon layers are formed in the material combustion process, the transmission of oxygen and heat is isolated, the heat exchange is interrupted, and the purpose of inhibiting the combustion is achieved. Therefore, the flame retardant is particularly suitable for flame retardant modification of glass fiber reinforced polypropylene and other flame retardants with good self-charring performance.

The melamine intumescent flame retardant system can simultaneously exert flame retardant effect on a condensed phase and a gas phase, so that the novel intumescent flame retardant system constructed on the basis of piperazine pyrophosphate replaces the traditional CFA system and has better application prospect. The strong self-charring performance of the piperazine pyrophosphate can effectively overcome the candle wick effect of glass fibers, so that the piperazine pyrophosphate is taken as a basis to supplement a gas source and an acid source, and the piperazine pyrophosphate has a great application prospect in glass fiber reinforced polypropylene.

Therefore, the glass fiber reinforced polypropylene molding material prepared by the invention has high flame retardant property and high thermal stability, can reliably meet UL 94V-0 under the condition of the sample thickness of 1.6mm, and can reliably meet the glowing filament requirement-glowing filament flammability index (GWFI) under all tested wall thicknesses: 960 ℃, Glow Wire Ignition Temperature (GWIT): 750 ℃. The invention can effectively solve the problem of insufficient halogen-free flame retardant grade of the glass fiber reinforced polypropylene.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) according to the halogen-free flame-retardant glass fiber reinforced polypropylene composition containing the flame-retardant stabilizer, three flame-retardant sources are integrated into one composition, the novel inorganic polymer flame retardant agent is adopted, piperazine phosphate is focused, the influence of a candlewick effect generated by glass fibers on the carbonizing performance of a traditional triazine carbonizing agent system is overcome, and the effective increase of carbon layers after the material is combusted is realized;

(2) in the aspect of gas phase, melamine derivative flame retardant with high dilution effect and free radical interruption and dilution effect is introduced, so that the flame retardant effect of the gas phase is greatly increased, the melamine derivative flame retardant and condensed phase flame retardant are mutually synergistic, and the negative influence caused by the glass fiber reinforced polypropylene candle wick effect is overcome;

(3) aiming at the system, a specific stabilizer combination is used, so that the prepared halogen-free flame-retardant polypropylene material can keep high flame retardance, high glow wire property, high strength and the like;

(4) the halogen-free flame-retardant glass fiber reinforced polypropylene material prepared from the halogen-free flame-retardant glass fiber reinforced polypropylene composition containing the flame-retardant stabilizer adopts a special preparation process and adjusts the screw combination, so that the glass fiber and the flame retardant composition are uniformly mixed, the halogen-free flame-retardant glass fiber reinforced polypropylene material can be used in electric appliance shells, capacitors, switches, automobile instrument seats, shells and other products, and the halogen-free flame-retardant glass fiber reinforced polypropylene material can meet the use requirements of materials with high flame retardance, high strength, no yellowing and the like. Can be used in a plurality of household fields such as automobiles, household appliances and the like.

Drawings

FIG. 1 is an SEM image of the residue of the long glass fiber reinforced polypropylene after combustion in comparative example 1;

FIG. 2 is an SEM image of the residue of the flame-retardant long glass fiber reinforced polypropylene obtained in example 8 after combustion.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

The following fire resistance classes were obtained according to UL 94:

HB: the lowest flame retardant rating in the UL94 standard. The burning speed is required to be less than 40mm/min for samples with the thickness of 3-13 mm; the burning speed of the sample with the thickness less than 3mm is less than 70 mm/min; or extinguished before the 100mm mark.

V-2: after two 10s burn tests on the samples, the flame was extinguished within 30 s. The cotton wool below 30cm can be ignited.

V-1: after two 10s burn tests on the samples, the flame was extinguished within 30 s. The cotton wool below 30cm cannot be ignited.

V-0: after two 10s burn tests on the samples, the flame was extinguished within 10 s. No combustible material can fall off.

The glow wire resistance was determined according to the glow wire test GWFI (glow wire flammability index) according to IEC 60695-2-12 and the glow wire ignition test GWIT (glow wire ignition temperature) according to IEC 60695-2-13.

In the case of the GWFI test, three specimens were tested with the aid of a glow wire at a temperature of 550-.

Using a comparable measurement procedure, the result reported is a glow wire ignition temperature which is 25K higher than the maximum glow wire temperature which does not cause ignition in three consecutive tests even in prolonged exposure to the glow wire. Ignition in this respect is considered to be a flame with a burning time of 5s or more.

The flowability of the moulding compositions was determined by determining the melt volume index (MVR) at 220 ℃/2.16 kg. A higher MVR value means better flowability in the injection molding process.