CN101328305A - A kind of halogen-free flame-retardant PBT/PC alloy composition and preparation method thereof - Google Patents

Abstract

The invention discloses a halogen-free flame-retardant PBT/PC alloy composition and a preparation method thereof. In terms of mass percentage, the composition is composed of the following components: 40%-50% PBT, 10%-20% PC, 23%-33% activated magnesium hydroxide, 3%-7% phosphate ester oligomer , 3% to 7% polysiloxane/acrylate graft copolymer, 3% to 7% novolac epoxy resin, 0.2% to 0.4% antioxidant and 0.4% to 0.8% processing aid. The method comprises the steps of dispersing and mixing the components in the formulation, melting, kneading, extruding, cooling, drying, pelletizing and packaging by means of a twin-screw machine. The present invention combines the flame-retardant charring effect of each added component and the interfacial interaction with the matrix, so that each component of the system forms an indispensable organic whole, and obtains a higher Flame retardant, and the system has good mechanical properties, thermal properties and processing properties.

Description

A kind of halogen-free flame-retardant PBT/PC alloy composition and preparation method thereof

technical field

The invention relates to a flame retardant, in particular to a halogen-free flame-retardant PBT/PC alloy composition and a preparation method thereof.

Background technique

Polybutylene terephthalate (PBT) is a thermoplastic engineering material with fast crystallization speed, which is easy to realize high-speed molding, has good rigidity and hardness, good creep and solvent resistance, anti-aging performance and can be Processability, low water absorption, but the use of PBT alone has defects such as easy shrinkage and deflection of the part, low heat distortion temperature, and flammability. The polycarbonate (PC) molecular chain contains a large number of benzene rings, which has a large steric hindrance, good rigidity and toughness, high char formation rate, and self-extinguishing. Blending a small amount of PC to modify PBT (that is, to form a PBT/PC alloy) can improve the self-extinguishing property and carbon-forming ability of PBT to a certain extent, and the impact resistance and heat resistance can be improved. PBT/PC alloy can obtain a certain flame retardancy by using halogen and antimony trioxide system flame retardancy, but this method of flame retardancy makes the alloy have poor arc tracking resistance, produces dense smoke when burning, and has environmental protection hazards. Regarding this type of alloy Halogen-free flame retardant has not been reported publicly yet. Chinese invention patent CN1789333 discloses a PC/PBT alloy environment-friendly flame-retardant technology mainly based on PC and supplemented by PBT. The patent uses aromatic phosphate ester and benzyl silicone composite flame retardant, with methyl methacrylate-butadiene-styrene graft copolymer (MBS) and styrene-maleic anhydride copolymer (SMAH) as a compatibilizer. The alloy matrix is mainly PC, and its flame retardancy is relatively easy to achieve, and compared with PC, PBT has an obvious price advantage. Therefore, compared with PC/PBT alloy, PBT/PC alloy with PBT as the main body realizes halogen-free resistance In addition, the flame retardant synergist phenylmethyl silicone used in this invention has a small interaction force with the PC and PBT substrates, so it is difficult to form a strong interface bond, and a large amount of MBS and SMAH are required in the system Compatibilizer; Moreover, all components of the system are organic polymer materials, which are not beneficial to the shrinkage and deflection of the part and the improvement of the heat distortion temperature.

Contents of the invention

The invention focuses on solving the existing problems in the field of PBT/PC alloy flame retardant technology, and provides a halogen-free PBT/PC alloy composition with excellent flame retardant performance, mechanical performance and thermal performance and a preparation method thereof.

In order to achieve the above invention, in the technical solution of the present invention, PBT and PC are used as base materials, and activated magnesium hydroxide and phosphate ester oligomers are added to improve flame retardancy, and polysilsesquioxane/acrylic esters are grafted The copolymer and phenolic epoxy resin increase the char formation rate of the system, improve the char layer structure, and increase the interaction of the components of the PBT, PC, and activated magnesium hydroxide multiphase flame retardant system at the same time. The specific technical scheme is as follows:

A halogen-free flame-retardant PBT/PC alloy composition, the formulation of which is composed of the following components in terms of mass percentage: 40% to 50% of PBT, 10% to 20% of PC, 23% to 33% of activated magnesium hydroxide, 3%~7% phosphate oligomer, 3%~7% polysiloxane/acrylate graft copolymer, 3%~7% novolac epoxy resin, 0.2%~0.4% antioxidant and 0.4% ~0.8% processing aid. The activated magnesium hydroxide is magnesium hydroxide surface-treated with silane coupling agent, titanate coupling agent, stearic acid or stearate, and the particle size is 0.5-10 μm. The activated magnesium hydroxide can be activated magnesium hydroxide by FM70D and FM70A of Guangdong Foshan Jinge Fire-fighting Materials Co., Ltd.

The phosphate oligomers are resorcinol diphosphate (RDP) and oligomeric bisphenol A bis(diphenyl phosphate) (BDP). Described polysiloxane/acrylate graft copolymer is high phenyl organopolysilsesquioxane/acrylate graft copolymer (Si-ACR), high phenyl organopolysilsesquioxane and The molar ratio of the polyacrylate in the graft copolymer is 0.8-2:1, and the preparation method is prepared according to the preparation method of the flame retardant interface modifier disclosed in the application number 200710032309.9. The method comprises the steps of:

(1) Add difunctional organosilane and trialkoxysilane organosilane monomer sequentially or evenly after mixing them into the aqueous solution in which anionic emulsifier or compound emulsifier is dissolved, and react at 30-60°C for 6-12 hours , to obtain a high phenyl organopolysilsesquioxane emulsion; the difunctional organosilane accounts for 10% to 45% by mole of the organosilane monomer, and the mole percentage of the organosilane monomer occupied by the trialkoxysilane is 50% to 85% %; the total mass of organosilane monomers is 25% to 40% of the water mass; the amount of emulsifier is 0.5% to 10% of the total mass of organosilane monomers, and the compound emulsifier is a mass ratio of 0.5 to 3:1 A mixture of anionic and nonionic emulsifiers;

(2) Adjust the pH value of the high phenyl organopolysilsesquioxane emulsion obtained in step (1) to 8-11 with alkaline solution, then add sodium dodecylbenzenesulfonate emulsifier, initiator and acrylate React for 4-8 hours at 50-95°C; then add sodium dodecylbenzenesulfonate emulsifier, initiator and methacrylate monomer, react for 4-8 hours at 50-95°C , to obtain a high phenyl organopolysilsesquioxane/acrylate composite emulsion, add a metal salt solution 0.5 to 2 times the quality of the emulsion, heat at 60 to 100°C for 5 to 10 hours, and wash the precipitated product , drying, to obtain high phenyl organopolysilsesquioxane/acrylate compound flame retardant interfacial modifier; wherein, sodium dodecylbenzenesulfonate consumption is the mass of acrylate or methacrylate monomer 0.5% to 5% of the mass of the initiator; the amount of the initiator is 0.1% to 1% of the mass of the acrylate or methacrylate monomer, and it is added at one time or added dropwise to an aqueous solution with a concentration of 10% by mass; The molar ratio of methacrylates and acrylates to acrylates is 0.5 to 5:1, and the ratio of the total moles of methacrylates and acrylates to the total moles of organosilane monomers is 0.15 to 1.5:1. The method adopts batch method, semi-continuous addition method, continuous addition method or pre-emulsification method.

The epoxy functionality of the novolac epoxy resin is 3.0-5.0, that is, the average number of epoxy groups on each molecule of the novolak epoxy resin is 3.0-5.0.

The antioxidant is a phenolic antioxidant and/or a phosphite antioxidant.

The processing aid is one or more of plasticizers, release agents, light stabilizers, pigments and dyes.

The preparation method of the above-mentioned halogen-free flame-retardant PBT/PC alloy composition: according to the formula mass percentage, PBT, PC, activated magnesium hydroxide, polysiloxane/acrylate graft copolymer, phosphate ester oligomer, phenolic After the epoxy resin, antioxidant and other processing aids are dispersed and mixed, they are melted, kneaded, extruded, cooled, dried, pelletized and packaged by a twin-screw extruder. At 230-260°C; in terms of mass percentage, the formulation of the halogen-free flame-retardant PBT/PC alloy composition consists of the following components: 40%-50% PBT, 10%-20% PC, 23%-33% activated hydroxide Magnesium, 3% to 7% phosphate oligomer, 3% to 7% polysiloxane/acrylate graft copolymer, 3% to 7% novolac epoxy resin, 0.2% to 0.4% antioxidant and 0.4% to 0.8% processing aids.

The invention uses activated magnesium hydroxide and phosphate ester oligomers to synergistically flame-retardant PBT/PC alloy, and uses polysiloxane/acrylic ester graft copolymer and phenolic epoxy resin to increase carbonization and has a certain compatibilization effect . The inorganic metal magnesium hydroxide flame retardant has a high decomposition temperature and a large heat absorption. The magnesium oxide generated by the decomposition adheres to the surface of combustibles to further prevent the combustion, and can also absorb a large amount of harmful gases produced by the combustion of rubber, plastics and other polymers. Gas, smoke and incompletely burned melting residues stop burning quickly, and no harmful substances are produced during the entire flame retardant process. At the same time, it has the functions of filling and improving the shrinkage flexibility and heat deformation temperature of the system. Guangdong Foshan Jinge Fire-fighting Material Co., Ltd. produces FM70D and FM70A magnesium hydroxide, which has a lubricating function and catalyzed carbon-forming polymer layer on the surface and in the microspace. Most of the particle sizes are 2 to 3 microns. The particle size distribution range is 0.5-10μm, the gradient is reasonable, it is easy to disperse in the alloy matrix, and it can form a good interface layer with PBT and PC. Phosphate oligomers containing flame-retardant element phosphorus and magnesium hydroxide have a flame-retardant synergistic effect by forming a compact charcoal layer during combustion, and phosphate oligomers also have a certain infiltration and plasticization effect on magnesium hydroxide. It can improve the poor processing fluidity of the system caused by the use of inorganic powder to activate magnesium hydroxide, and can also inhibit the transesterification reaction between PBT and PC, and reduce the performance degradation of the matrix caused by the transesterification reaction. The polysiloxane in the polysiloxane/acrylate graft copolymer interacts with the matrix to form a solid carbon layer containing silicon when it burns, and the novolac epoxy resin has a high char formation rate when it is burned. The char formation is greatly increased, the carbon layer structure is improved, and the barrier effect is strengthened, and the polysiloxane/acrylate graft copolymer has acrylate groups, and the molecular structure of the novolak epoxy resin contains epoxy groups. There is a chemical interaction between the analogous group and PBT, PC, and activated magnesium hydroxide, which has a certain capacity-enhancing and chain-extending effect, making each component of the system form an organic whole, with strong flame retardancy, good mechanical properties, and thermal properties.

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

(1) Realized the halogen-free and environmentally friendly flame retardant of PBT/PC alloy, using 23% to 33% activated magnesium hydroxide, supplemented by phosphate oligomer flame retardant synergist, polysiloxane/acrylate joint The branch copolymer and phenolic epoxy resin carbon forming agent make the vertical combustion of PBT/PC alloy completely reach the UL94V-0 level.

(2) Compared with the corresponding PBT/PC alloy, the linear thermal expansion coefficient of the PBT/PC alloy composition is reduced by more than 30%, the heat distortion temperature is increased by more than 40°C, and the material's shrinkage and deflection resistance and heat resistance stability are enhanced.

Detailed ways

The present invention will be further described below in conjunction with specific examples, but the scope of protection claimed by the present invention is not limited to the scope described in the examples.

For the preparation method of the polysiloxane/acrylate graft copolymer used in the following examples, refer to the preparation of the flame retardant interfacial modifier disclosed in the application number 200710032309.9. A typical preparation method is: adding octamethyltetrasiloxane (D4) and phenyltrimethoxysilane (PTMS) to an aqueous solution of dodecylbenzenesulfonic acid and reacting at 50°C for 8 hours to obtain high phenyl Organic polysilsesquioxane emulsion; adjust the pH value to 10 with sodium hydroxide solution, then add sodium dodecylbenzenesulfonate, potassium persulfate and butyl acrylate, and react at 90°C for 6 hours; then add Sodium dodecylbenzenesulfonate, potassium persulfate and methyl methacrylate were reacted at 90°C for 8 hours to obtain a high-phenyl organopolysilsesquioxane/acrylate composite emulsion, and the mass of the emulsion was doubled The mass percentage of 10% calcium chloride aqueous solution was heated at 95°C for 10 hours to break the emulsion, and the precipitated product was washed and dried to obtain a high phenyl organopolysilsesquioxane/acrylate graft copolymer (Si-ACR) Flame retardant interface modifier; the molar ratio of D4 to PTMS is 1:4; the molar ratio of methyl methacrylate to butyl acrylate is 1:1, high phenyl organopolysilsesquioxane and polyacrylate The molar ratio ( _RSi/ester ) in the graft copolymer is 0.8-2:1.

The novolac epoxy resin used is formed by condensation of low-molecular-weight phenolic resin and epichlorohydrin under an acid catalyst, and has the advantages of both phenolic resin and bisphenol A epoxy resin. According to the different molecular weight and hydroxyl content of the novolac resin, novolac epoxy resins with different molecular weights and epoxy functionalities can be synthesized. The present invention selects epoxy novolac resins with epoxy functionalities of 3.0 to 5.0, high viscosity semi-solid or solid form .

The activated magnesium hydroxide is magnesium hydroxide surface-treated with silane coupling agent, titanate coupling agent, stearic acid or stearate, and the particle size is 0.5-10 μm. The activated magnesium hydroxide uses FM70D and FM70A of Guangdong Foshan Jinge Fire Protection Materials Co., Ltd. to activate magnesium hydroxide.

If FM70D and FM70A brand activated magnesium hydroxide flame-retardant PBT/PC alloys are used alone, the mass percentage of magnesium hydroxide in the formula is more than 50%, and the vertical combustion level can reach UL94V-0@3.2mm, but due to the large amount of addition, the system mechanics The performance is poor; the combination of 45% activated magnesium hydroxide and 5% phosphate oligomer in the formula can make the PBT/PC alloy reach the same flame retardancy level, and the mechanical properties are better than the flame retardancy of activated magnesium hydroxide alone. It has been improved on the basis of the above, but the impact strength is still kept at a low level; the use of about 10% by mass of polysiloxane/acrylate graft copolymer and novolak epoxy resin can make the amount of activated magnesium hydroxide Reduced to 23-33%, the performance of all aspects can be greatly improved.

Example 1:

416g of PBT, 176g of PC, 240g of FM70D, 50g of Si-ACR with R _Si/ester of 0.8, 60g of RDP, 50g of novolak epoxy resin with epoxy functionality of 3.0, 4g of dioctyl phthalate plasticizer, 2g of hindered phenolic antioxidant 1010 and 2g of silicone mold release agent are dispersed and mixed by a high-speed mixer, melted, kneaded, extruded, cooled, dried, pelletized and packaged by a twin-screw machine. The temperature of each zone of the twin-screw extruder barrel used is 230-260°C. The prepared composition is injection-molded into a standard sample for testing according to a standard size, and the physical properties are tested according to international standards.

According to the above preparation method, the material example 1 of the present invention and the formulations of the other eight examples are shown in Table 1 to Table 2.

As can be seen from Table 1 and Table 2, all examples of UL-94 vertical combustion pass the V-0 level (3.2mm). The flame retardant system magnesium hydroxide adopted in the present invention has a flame retardant synergistic effect with a phosphate oligomer, filling and plasticizing complement each other, and has good processing fluidity. The two char-forming agents used respectively have acrylate groups and epoxy groups, and the two types of groups have compatibilization and chain extension effects with PBT, PC, and activated magnesium hydroxide, so that the components of the system form defects. An indispensable organic whole, high flame retardancy is obtained at a low dosage of magnesium hydroxide, and the mechanical properties of the system are higher than those of PBT/PC alloy except for the elongation at break which is lower than that of PBT/PC alloy , the heat distortion temperature increases above 40°C, and the material's resistance to shrinkage and deflection is significantly enhanced.

Table 1 embodiment formula list and material performance testing result

performance Compared Example 1 Example 2 Example 3 Example 4 PBT(g) 696 416 474 430 400 PC(g) 296 176 118 154 140 Si-ACR(g) 0 50 (RSi _/ester = 0.8) 30(RSi _/ester =2) 50 (RSi _/ester = 1.5) 70 (RSi _/ester = 1.2) Novolac epoxy resin (g) 0 50(n=3.0) 70 (n=3.5) 60 (n=4.0) 30(n=4.5) Activated magnesium hydroxide (g) 0 240 (FM70D) 250 (FM70A) 240 (FM70D) 300(FM70A) Phosphate oligomer (g) 0 60(RDP) 50(RDP) 60(BDP) 50(BDP) Plasticizer (g) 4 (dioctyl phthalate) 4 (dioctyl phthalate) 4 (zinc stearate) 2 (magnesium stearate) 4 (calcium stearate) Antioxidant (g) 2(B215) 2 (Hindered phenolic antioxidant 1010) 2 (phosphite antioxidant 168) 2(B215) 3(B215) Other (g) 2 (silicone release agent) 2 (silicone release agent) 2 (light stabilizer GW-540) 2 (light stabilizer Chimassorb119) 3 (light stabilizer Chimassorb2020) Izod notched impact strength (kJ/m ² ) 5.3 6.1 5.7 6.6 5.5 Tensile strength (MPa) 63 65 67 60 65 Bending strength (MPa) 87 90 85 92 93 Elongation at break (%) 60 30 28 twenty four twenty three Heat distortion temperature (℃, 0.45MPa) 81 119 122 124 140 Linear thermal expansion coefficient (×10 ⁵ cm/cm.℃) 8.7 5.4 5.3 5.5 5.1 UL94 vertical combustion rating (3.2mm) NR V-0 V-0 V-0 V-0

Table 2 embodiment formula table and material performance testing result

performance Example 5 Example 6 Example 7 Example 8 Example 9 PBT(g) 400 432 400 500 400 PC(g) 113 100 139 100 200 Si-ACR(g) 70(RSi _/ester =1) 60 (RSi _/ester = 1.5) 70 (RSi _/ester = 1.8) 51 (RSi _/ester = 2) 50 (RSi _/ester = 0.8) Novolac epoxy resin (g) 30 (n=5.0) 50(n=3.3) 50(n=4.2) 40 (n=4.6) 44 (n=4.0) Activated magnesium hydroxide (g) 330 (FM70D) 280(FM70A) 300(FM70D) 240 (FM70A) 230 (FM70D) Phosphate oligomer (g) 50(RDP) 70(BDP) 30(BDP) 60(BDP) 70(RDP) Plasticizer (g) 3 (polyethylene wax) 4 (zinc stearate) 5 (magnesium stearate) 4 (calcium stearate) 2 (dioctyl phthalate) Antioxidant (g) 2(B215) 4 (Hindered phenolic antioxidant 1010) 3(B215) 2(B215) 2 (phosphite antioxidant 168) Other (g) 2 (light stabilizer Chimassorb2020) 0 3 (silicone release agent) 3 (light stabilizer GW-540) 2 (silicone release agent) Izod notched impact strength (kJ/m ² ) 5.6 6.2 6.7 5.9 7.2 Tensile strength (MPa) 78 72 75 77 72 Bending strength (MPa) 93 92 91 87 85 Elongation at break (%) twenty three 27 28 28 20 Heat distortion temperature (℃, 0.45MPa) 146 134 142 123 146 Linear thermal expansion coefficient (×10 ⁵ cm/cm.℃) 4.9 5.1 5.0 5.4 5.7 UL94 vertical combustion rating (3.2mm) V-0 V-0 V-0 V-0 V-0

Claims (8)

1, a kind of fire retardant PBT with no halogen/PC alloy composite, it is characterized in that, by mass percentage, its prescription is made up of following component: 40%～50%PBT, 10%～20%PC, 23%～33% activation magnesium hydroxide, 3%～7% phosphoric acid ester oligopolymer, 3%～7% polysiloxane/acrylate quasi-graft copolymer, 3%～7% novolac epoxy, 0.2%～0.4% oxidation inhibitor and 0.4%～0.8% processing aid.

2, fire retardant PBT with no halogen according to claim 1/PC alloy composite, it is characterized in that, described activation magnesium hydroxide is for to carry out the surface-treated magnesium hydroxide with silane coupling agent, titanate coupling agent, stearic acid or stearate, and particle diameter is 0.5～10 μ m.

3, fire retardant PBT with no halogen according to claim 1/PC alloy composite is characterized in that, described phosphoric acid ester oligopolymer is Resorcinol biphosphonate or low poly bisphenol two (diphenyl phosphoester).

4, fire retardant PBT with no halogen according to claim 1/PC alloy composite, it is characterized in that, described polysiloxane/acrylate quasi-graft copolymer is the organic polysilsesquioxane/acrylate graft copolymers of high phenyl, and organic polysilsesquioxane of high phenyl and polyacrylic ester mol ratio in graft copolymer is 0.8～2: 1.

5, fire retardant PBT with no halogen according to claim 1/PC alloy composite is characterized in that, the epoxy functionalities of described novolac epoxy is 3.0～5.0.

6, fire retardant PBT with no halogen according to claim 1/PC alloy composite is characterized in that, described oxidation inhibitor is phenolic antioxidant and/or phosphite ester kind antioxidant.

7, fire retardant PBT with no halogen according to claim 1/PC alloy composite is characterized in that, described processing aid is one or more in softening agent, releasing agent, photostabilizer, pigment and the dyestuff.

8, the preparation method of the described fire retardant PBT with no halogen of claim 1/PC alloy composite, it is characterized in that: press prescription quality per-cent, after PBT, PC, activation magnesium hydroxide, polysiloxane/acrylate quasi-graft copolymer, phosphoric acid ester oligopolymer, novolac epoxy, oxidation inhibitor and other processing aid dispersing and mixing, by the dual-screw-stem machine fusion, mixing, extrude, cool off, dry, pelletizing and packing, each subregion temperature of used double-screw extruding machine barrel remains on 230～260 ℃;

By mass percentage, fire retardant PBT with no halogen/PC alloy combination composition formula is made up of following component: 40%～50%PBT, 10%～20%PC, 23%～33% activation magnesium hydroxide, 3%～7% phosphoric acid ester oligopolymer, 3%～7% polysiloxane/acrylate quasi-graft copolymer, 3%～7% novolac epoxy, 0.2%～0.4% oxidation inhibitor and 0.4%～0.8% processing aid.