CN103819817A - Polypropylene composition with high fluidity and high dimensional stability and preparation method thereof - Google Patents

Abstract

The invention discloses a polypropylene composition with high fluidity and high dimensional stability and a preparation method thereof. The components of the polypropylene composition with high fluidity and high dimensional stability are (parts by weight): homopolypropylene: 10-60 parts, Copolymer polypropylene: 10-40 parts, thermoplastic elastomer: 10-25 parts, polyethylene: 3-8 parts, mineral filler: 0-35 parts, heat stabilizer: 0.2-1 part, light stabilizer: 0.2-1 part parts, coupling agent: 0.3-1 parts, other additives: 0.5-3 parts. Preparation method: Weigh the raw materials according to the above weight ratio; stir and mix at low speed for 2-8 minutes to obtain a premix; add the premix into a twin-screw extruder, melt and blend, extrude and granulate. The product of the invention has high fluidity, low shrinkage rate and good dimensional stability. The invention has mature production formula, simple extrusion process, adjustable product performance through formula, controllable performance and wide range of injection molding process.

Description

A kind of polypropylene composition with high fluidity and high dimensional stability and preparation method thereof

technical field

The invention relates to the technical field of polymer composite materials, in particular to a polypropylene composition with high fluidity and high dimensional stability and a preparation method thereof.

Background technique

With the rapid development of the automobile industry, polypropylene (PP) composite materials with light weight, corrosion resistance, heat resistance, aging resistance, impact resistance, and balance of rigidity and toughness have been increasingly used. Modified PP is used in automobiles today. There are more than a dozen parts of the material, and the automobile bumper formed by modified PP material is the most representative part, and the design of the current bumper tends to be thinner, which requires the material to have good fluidity and high toughness. Good dimensional stability. Automobile bumper products have two shrinkage processes before assembly, that is, shrinkage after demoulding and cooling during injection molding and shrinkage after spraying and baking. The shrinkage during spraying and baking is uncontrollable during the product molding process, which will cause After spraying, the size fluctuates greatly and the product cannot be assembled.

In recent years, some bumper materials have been developed domestically. For example, the Chinese patent document with the application publication number CN101993563A discloses a preparation method of a special material for automobile bumper polypropylene. Copolymerized polypropylene is used as the base resin, and maleic anhydride is used as the base resin. Branches, nucleating agents and inorganic filler talcum powder improve the compatibility between materials and the modulus of the system, control the crystal size and improve thermal stability, and use toughening agents to blend and toughen, and process modified masterbatches to adjust processing flow The fluidity of the prepared bumper special material is 4.8g/10min, the tensile strength is 21.6Mpa, the cantilever beam impact is 548J/m and 98.7 J/m at 23°C and -20°C respectively, and the molding shrinkage rate is 0.91 %, the material has high impact strength and low shrinkage, but the material has low fluidity. During injection molding, not only the processing parameter setting range is narrow, but also problems such as product appearance defects are prone to occur.

Another example is that the Chinese patent document with the application publication number CN101693777A provides a material for automobile bumper and its preparation method. The composition ratio includes polypropylene 49%-69%, saturated ethylene-octene copolymer 5%-25%, Calcium sulfate whisker 10%~30%, polypropylene grafted maleic anhydride copolymer 5%~15%, nucleating agent 0.1%~0.2%, antioxidant 0.3%~0.6%, lubricant 0.2%~0.5% , the extrusion processing temperature is 170 ℃ ~ 230 ℃, calcium sulfate whiskers are added through the side feeding port, the notched impact energy of the cantilever beam of the prepared material can reach 120 J/m ~ 650J/m, and the melt index is 13.1g/10min ~ 21.3g/10min, the molding shrinkage rate can reach 0.9%~1.3%. The automobile bumper material prepared in this patent document has good rigidity and toughness balance and fluidity, but the shrinkage rate of the material is relatively large, which is not suitable for the production of mold structures. Products with complex designs and low shrinkage requirements.

The existing technology cannot effectively control the fluctuation range of the size of the product during the injection molding and baking spraying process; the melt rate of the material is low, and it is not suitable for the production of bumper products with thin walls, complex appearance design and high appearance requirements.

Other related patents:

1. A method for preparing polypropylene with low shrinkage, high flow and high toughness, application number: 200710047775.4;

2. A special polypropylene compound for automobile bumper with low shrinkage and its preparation method, application number: 201210460696.7;

3. A special polypropylene composite material for thin-walled automobile bumpers and its preparation method, application number: 201210461727.0;

4. A polypropylene composition with good dimensional stability and its preparation method and application, application number: 201210372018.5;

5. A special material for polypropylene automobile bumper and its preparation method, application number: 201210111297.x;

6. A modified polypropylene material for thin-walled bumpers and its preparation method, application number: 201010196779.0;

7. A weather-resistant and impact-resistant polypropylene special material for automobile bumpers and its preparation method, application number: 201310157330.7.

Contents of the invention

The technical problem to be solved by the present invention is to provide a high flow and high dimensional stability polypropylene composition and its preparation method, which can better control the size fluctuation of large thin-walled sprayed products during injection molding and baking spraying Scope; Solve the problem of appearance defects that are easy to occur during injection molding of large thin-walled sprayed products.

The technical solution of the present invention is: the components of the high-fluidity high-dimensional stability polypropylene composition are (parts by weight): homopolypropylene: 10-60 parts, copolymerized polypropylene: 10-40 parts, thermoplastic elastomer : 10-25 parts, polyethylene: 3-8 parts, mineral filler: 0-35 parts, heat stabilizer: 0.2-1 part, light stabilizer: 0.2-1 part, coupling agent: 0.3-1 part, others Auxiliary: 0.5-3 parts; the other auxiliaries are white oil, calcium stearate, zinc stearate, sodium polyethylene, N,N'-ethylene bisstearamide, acrylate-carboxylic acid-ethylene One or more of terpolymer and aliphatic epoxy resin.

Melt index of the homopolypropylene: 70-120g/10min; melt index of the copolymerized polypropylene: 20-40 g/10min, shrinkage rate: 0.7-0.9%.

The thermoplastic elastomer is EPDM rubber, ethylene-octene copolymer, ethylene-butylene copolymer, styrene-butadiene-styrene terpolymer, hydrogenated styrene-butadiene-styrene One or more of the terpolymers;

The polyethylene is one or more of linear low-density polyethylene, low-density polyethylene, and high-density polyethylene;

The mineral filler is one or more of talcum powder, mica powder, wollastonite, and montmorillonite; the particle size of the mineral filler is 0.5 to 5 microns;

The heat stabilizer is one or more of phenolic antioxidants, phosphite heat stabilizers, and thioester heat stabilizers;

The coupling agent is one or more of silane coupling agent, titanate coupling agent, aluminate coupling agent; the light stabilizer is hindered amine light stabilizer, salicylate One or more of ultraviolet absorbers, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, substituted acrylonitrile ultraviolet absorbers and triazine ultraviolet absorbers.

The use of the above-mentioned high-flow and high-dimensional-stability polypropylene composition is used to prepare large-scale thin-walled sprayed products or appearance non-sprayed products; the large-scale thin-walled sprayed product is an automobile bumper.

A preparation method for a polypropylene composition with high fluidity and high dimensional stability, comprising the following steps:

A. Mixing of raw materials: Weigh raw materials according to the following proportions by weight: homopolypropylene: 10-60 parts, copolymerized polypropylene: 10-40 parts, thermoplastic elastomer: 10-25 parts, polyethylene: 3-8 parts , mineral filler: 0-35 parts, heat stabilizer: 0.2-1 part, light stabilizer: 0.2-1 part, coupling agent: 0.3-1 part, other additives: 0.5-3 parts, the other additives It is one of white oil, calcium stearate, zinc stearate, sodium polyethylene, N,N'-ethylene bisstearamide, acrylate-carboxylic acid-ethylene terpolymer and aliphatic epoxy resin One or several kinds; first add homopolypropylene, copolymerized polypropylene, thermoplastic elastomer and polyethylene into the mixer for homogeneous mixing, then add coupling agent for homogeneous mixing, and then add other additives, heat stabilizers, and light stabilizers Homogeneously mix with mineral fillers; stir and mix at low speed for 2-8 minutes to obtain a premix;

B. Add the premix obtained in the above steps into a twin-screw extruder, melt and blend at a temperature of 170-240° C., extrude and granulate to obtain a polypropylene composition with high flow and high dimensional stability.

The high flow and high dimensional stability polypropylene composition in the present invention has high fluidity, low shrinkage and good dimensional stability. The present invention provides high fluidity, low shrinkage, low aftershrinkage, low temperature resistance, aging resistance, size A polypropylene composition with good stability and its preparation method, by adding low-shrinkage polypropylene, mineral powder, thermoplastic elastomer and related additives to control the product injection molding cooling process, through high-fluidity polypropylene and corresponding additives Solve the appearance defects that are easy to occur during product injection molding. The invention has mature production formula, simple extrusion process, product performance can be adjusted through the formula, performance is controllable, injection molding process range is wide, and it is suitable for the production of large thin-wall sprayed products such as automobile bumpers with high requirements for assembly size and appearance. Non-spraying products can meet the molding requirements and assembly requirements of current automobile bumper products.

Detailed ways

The key points of the present invention are: the thickness of the automobile bumper, the design structure is complex, and the material melt flow rate is high to meet the appearance requirements of the product. Automobile bumper materials require low shrinkage and low back shrinkage.

The high flow and high dimensional stability polypropylene composition comprises the following components (parts by weight): homopolypropylene 10-60, copolymerized polypropylene 10-40, thermoplastic elastomer 10-25, polyethylene 3-8, mineral Filler 0-35, heat stabilizer 0.2-1, light stabilizer 0.2-1, coupling agent 0.3-1, other additives 0.5-3.

The melt index of the homopolypropylene is 70-120g/10min.

Melt index of the copolymerized polypropylene: 20-40 g/10min, shrinkage rate: 0.7-0.9%.

The thermoplastic elastomer is EPDM rubber, ethylene-octene copolymer, ethylene-butylene copolymer, styrene-butadiene-styrene terpolymer, hydrogenated styrene-butadiene-styrene One or more of the terpolymers.

The polyethylene is one or more of linear low-density polyethylene, low-density polyethylene and high-density polyethylene.

The mineral filler has a particle size of 0.5 to 5 microns.

The phenol heat stabilizer is antioxidant 1010, the phosphite heat stabilizer is antioxidant 168, and the thioester heat stabilizer is high molecular weight, high temperature resistant antioxidant 412S.

The light stabilizer is compounded of hindered amine HALS and ultraviolet light absorber, the hindered amine is 3808PP5, and the ultraviolet light absorber is UV-531.

The coupling agent is one or more of silanes, titanate, and titanate.

The other additives are calcium stearate, zinc stearate, paraffin, white oil, N,N'-ethylene bisstearamide, acrylate-carboxylic acid-ethylene terpolymer, aliphatic epoxy resin one or more of them.

The preparation method of described high flow high dimensional stability polypropylene composition comprises the following steps:

Step 1. Add the homopolypropylene, copolymerized polypropylene, thermoplastic elastomer, and linear low-density polyethylene into the mixer for uniform mixing according to the weight ratio, then add the coupling agent for uniform mixing, and then add other additives , heat stabilizer, light stabilizer, mineral filler, mixed at a low speed for 2-8 minutes to obtain a premix.

Step 2. Add the premix obtained in step 1 to the twin-screw extruder, set the feeding frequency to 6-10Hz, the frequency of the host machine to 22-26Hz, and set the temperature of the extrusion section to 170-180°C, 190-230°C , 190-230°C, 190-230°C, 190-230°C, 185-225°C, 185-225°C, 185-225°C, 200-240°C, the extruded plastic strips are water-cooled, the water tank temperature is 20-60°C, Air-dried and pelletized to obtain a polypropylene composition with high flow and high dimensional stability.

The product of the present invention has been installed and applied in a vehicle through experiments, and there is no bad feedback. The present invention has covered the modified polyolefin formulation of the technology used in automobile bumpers.

The present invention will be further described below through embodiment.

Table 1 is the component distribution ratio of five examples of high flow and high dimensional stability polypropylene composition prepared by the above method

Carry out performance test to a kind of high fluidity high dimensional stability polypropylene composition obtained in embodiment 1 to embodiment 5, sample is tested with national standard, the disc cavity mold of 103.2 * 4mm is selected for shrinkage test, sample and disc Conditioned in an environment of 23±1°C and humidity of 55% for 48 hours, the post-shrinkage of the disc simulates the spraying and baking temperature of bumper products. After two hours in an air blast oven at 90°C, it is at 23±1°C and humidity of 55%. Adjusted in the environment for 48 hours to carry out the post-shrinkage test, the test results are shown in Table 2:

The use of the above-mentioned high-flow and high-dimensional-stability polypropylene composition is used to prepare large thin-walled sprayed products (such as: automobile bumpers) or non-sprayed products with high requirements on assembly size.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims (10)

1. A high flow and high dimensional stability polypropylene composition, characterized in that, the components of the high flow and high dimensional stability polypropylene composition are (parts by weight): homopolypropylene: 10-60 parts, Copolymer polypropylene: 10-40 parts, thermoplastic elastomer: 10-25 parts, polyethylene: 3-8 parts, mineral filler: 0-35 parts, heat stabilizer: 0.2-1 part, light stabilizer: 0.2-1 part parts, coupling agent: 0.3-1 parts, other additives: 0.5-3 parts; said other additives are white oil, calcium stearate, zinc stearate, sodium polyethylene, N,N'-ethylene One or more of bis-stearamide, acrylate-carboxylic acid-ethylene terpolymer and aliphatic epoxy resin. 2. the high flow high dimensional stability polypropylene composition according to claim 1, is characterized in that, The melt index of the homopolypropylene is 70-120g/10min; the melt index of the copolymerized polypropylene is 20-40 g/10min, and the shrinkage rate is 0.7-0.9%; The thermoplastic elastomer is EPDM rubber, ethylene-octene copolymer, ethylene-butylene copolymer, styrene-butadiene-styrene terpolymer, hydrogenated styrene-butadiene-styrene One or more of the terpolymers; The polyethylene is one or more of linear low-density polyethylene, low-density polyethylene, and high-density polyethylene; The mineral filler is one or more of talcum powder, mica powder, wollastonite, and montmorillonite; the particle size of the mineral filler is 0.5 to 5 microns; The heat stabilizer is one or more of phenolic antioxidants, phosphite heat stabilizers, and thioester heat stabilizers; The coupling agent is one or more of silane coupling agent, titanate coupling agent and aluminate coupling agent; The light stabilizer is hindered amine light stabilizer, salicylate ultraviolet absorber, benzophenone ultraviolet absorber, benzotriazole ultraviolet absorber, substituted acrylonitrile ultraviolet absorber and triazine ultraviolet absorber One or more of the absorbents. 3. The high flow and high dimensional stability polypropylene composition according to claim 1, characterized in that, the components of the high flow and high dimensional stability polypropylene composition are (parts by weight): homopolypropylene: 36.6 parts, polypropylene copolymer: 40 parts, thermoplastic elastomer: 14 parts, polyethylene: 8 parts, mineral filler: 0 parts, heat stabilizer: 0.3 part, light stabilizer: 0.4 part, coupling agent: 0.2 part, Other additives: 0.5 parts. 4. The high flow and high dimensional stability polypropylene composition according to claim 1, characterized in that, the components of the high flow and high dimensional stability polypropylene composition are (parts by weight): homopolypropylene: 31.3 parts, polypropylene copolymer: 36 parts, thermoplastic elastomer: 15 parts, polyethylene: 6 parts, mineral filler: 10 parts, heat stabilizer: 0.3 part, light stabilizer: 0.4 part, coupling agent: 0.5 part, Other additives: 0.5 parts. 5. The high flow and high dimensional stability polypropylene composition according to claim 1, characterized in that, the components of the high flow and high dimensional stability polypropylene composition are (parts by weight): homopolypropylene: 28.3 parts, polypropylene copolymer: 28 parts, thermoplastic elastomer: 18 parts, polyethylene: 4 parts, mineral filler: 20 parts, heat stabilizer: 0.3 part, light stabilizer: 0.4 part, coupling agent: 0.5 part, Other additives: 0.5 parts. 6. The high flow and high dimensional stability polypropylene composition according to claim 1, characterized in that, the components of the high flow and high dimensional stability polypropylene composition are (parts by weight): homopolypropylene: 27.3 parts, polypropylene copolymer: 25 parts, thermoplastic elastomer: 17 parts, polyethylene: 4 parts, mineral filler: 25 parts, heat stabilizer: 0.3 part, light stabilizer: 0.4 part, coupling agent: 0.5 part, Other additives: 0.5 parts. 7. The high flow and high dimensional stability polypropylene composition according to claim 1, characterized in that, the components of the high flow and high dimensional stability polypropylene composition are (parts by weight): homopolypropylene: 22.3 parts, polypropylene copolymer: 20 parts, thermoplastic elastomer: 18 parts, polyethylene: 3 parts, mineral filler: 35 parts, heat stabilizer: 0.3 part, light stabilizer: 0.4 part, coupling agent: 0.5 part, Other additives: 0.5 parts. 8. The purposes of the high flow high dimensional stability polypropylene composition described in any one in claim 1 to 7, be used for preparing large-scale thin-wall sprayed product or appearance non-sprayed product; Described large-scale thin-walled sprayed product is automobile bumper. 9. A preparation method for a polypropylene composition with high fluidity and high dimensional stability, comprising the following steps: A. Mixing of raw materials: Weigh raw materials according to the following proportions by weight: homopolypropylene: 10-60 parts, copolymerized polypropylene: 10-40 parts, thermoplastic elastomer: 10-25 parts, polyethylene: 3-8 parts , mineral filler: 0-35 parts, heat stabilizer: 0.2-1 part, light stabilizer: 0.2-1 part, coupling agent: 0.3-1 part, other additives: 0.5-3 parts, the other additives It is one of white oil, calcium stearate, zinc stearate, sodium polyethylene, N,N'-ethylene bisstearamide, acrylate-carboxylic acid-ethylene terpolymer and aliphatic epoxy resin One or several kinds; first add homopolypropylene, copolymerized polypropylene, thermoplastic elastomer and polyethylene into the mixer for homogeneous mixing, then add coupling agent for homogeneous mixing, and then add other additives, heat stabilizers, and light stabilizers Homogeneously mix with mineral fillers; stir and mix at low speed for 2-8 minutes to obtain a premix; B. Add the premix obtained in the above steps into a twin-screw extruder, melt and blend at a temperature of 170-240° C., extrude and granulate to obtain a polypropylene composition with high flow and high dimensional stability. 10. The preparation method of the high flow high dimensional stability polypropylene composition according to claim 9 is characterized in that, in step B, setting feed frequency is 6-10Hz, host frequency 22-26Hz, extruding section The temperature is set to 170-180°C, 190-230°C, 190-230°C, 190-230°C, 190-230°C, 185-225°C, 185-225°C, 185-225°C, 200-240°C. The plastic strips are water-cooled, the temperature of the water tank is 20-60°C, air-dried and cut into pellets.