CN110483829A - A kind of low irradiation intensity prepares the preparation method of high-strength polypropylene expanded bead (EPP) - Google Patents

Abstract

The invention relates to a method for preparing high-strength expanded polypropylene beads (EPP) with low irradiation intensity. The agent is compounded and granulated in a parallel twin-screw extruder, and after being irradiated by high-energy electron rays, then adding a carboxyl group with a single functional group, or a hydroxyl group, or an amino long-chain structure substance at the end, or a carboxyl group with two or more functional groups, Or hydroxyl, or amine-based substances as chain extenders and other functional additives, re-extruded by twin-screws, water-cooled strands, pelletized, dried, and foamed by physical foaming agent batch method to obtain a high-efficiency Melt strength expanded polypropylene beads (EPP). The processing process of the invention is green and pollution-free, and the material structure is controllable. The random polypropylene foam material prepared by the method of the invention is a low-VOC content, pressure-resistant cushioning and heat-insulating material, and has excellent high strength and high resilience. Shock absorption and energy absorption, heat resistance, oil resistance, easy molding, can be widely used in military industry, automobile, construction, children's toys, food packaging materials, household appliances and other fields.

Description

A preparation of high-strength expanded polypropylene beads (EPP) with low irradiation intensity method

technical field

The invention relates to the technical field of polymer foam materials, and more specifically, the invention relates to a polypropylene foam particle and a preparation method thereof.

Background technique

EPP has a special cell structure (good cushioning), excellent shock resistance and energy absorption, light specific gravity (17-100kg/m3), high recovery rate after deformation, chemical resistance, and wide service temperature (-40 ° C ~ 110 ° C ), wide range of foaming ratio (5-60 times), oil resistance and heat insulation, etc. At the same time, the odor level of EPP can be controlled within 2.5, no organic volatiles, no benzene, aldehydes, ketones and other harmful substances , which can meet the strict requirements of automotive OEMs on the smell of automotive interiors. Because of these advantages at the same time, EPP is widely used in automobiles, such as car bumpers, seat systems, trunk tool boxes, car sun visors, buffer protection blocks, auto parts turnover packaging, commercial vehicle sleeper tool boxes , new energy vehicle high flame retardant series batteries, high-end car sound insulation and noise reduction partitions, etc. Of course, in addition to the automotive industry, EPP has shown its wide range of uses in packaging, home appliances, marine supplies and other fields. Although EPP materials have huge potential market applications, from the product application market and literature research, the raw materials for real industrial applications are mainly provided by a few countries such as Japan, South Korea, and Singapore; Product production, but has not formed a large-scale application in the market. As a foaming material with great potential, EPP currently has bottlenecks that limit its wide application in terms of material cost, production process, and material modification design. .

The high-energy ray irradiation method puts the polymer in a radiation field, and under the action of high-energy rays (mainly γ-rays, X-rays, and high-energy electron beams, etc.), free radicals are generated in the solid polymer, triggering a series of chemical reactions, thereby A long-chain branched structure is formed inside the polymer, which improves the melt strength of the polymer. Irradiation grafting branching has the advantages of low cost of irradiation light source, no excessive damage to materials, easy control of reaction degree, and basically no impact on the environment during the reaction process, no odor, etc., so it has attracted more and more attention. However, due to the poor penetration ability of the irradiated light on the material, the surface or sub-surface of the material is damaged. In order to achieve a better irradiation effect, the irradiation modification of polypropylene generally requires a dose of more than tens of KGry. In terms of the selection of branch monomers and the coordination of irradiation dose, the development of a preparation method for expanded polypropylene particles with low irradiation intensity, high grafting efficiency, and green processing process, the formation of a simple preparation process, less investment, and high popularity Appropriate EPP raw material modification technology, getting rid of the restriction of raw material dependence on imports, will have an important significance and role in the country's national economic and social development.

Contents of the invention

The object of the present invention is to provide a kind of adopting glycidyl methacrylate (ether) as grafting monomer, by high-energy irradiation technology, introduce short chain on polypropylene molecular chain, further increase branch length by chain extender , using low-dose high-energy irradiation to develop a preparation method for expanded polypropylene particles with low irradiation intensity, high grafting efficiency, and green processing, to form EPP with simple preparation process, low investment, and high universality Raw material modification technology. Using this technology, we have prepared a high melt strength, can flexibly adjust the size of the microporous structure of the EPP foam material, and prepared an EPP foam material with high strength, high resilience and excellent conductivity with a microporous structure.

1. A preparation method for preparing high-strength expanded polypropylene beads (EPP) with low irradiation intensity, the specific formula is as follows (the dosage refers to the share in 100 parts): the dosage of random polypropylene powder is 50-95 2-20 parts of glycidyl methacrylate (ether), 0.005-5 parts of stabilizer; 1-15 parts of chain extender; 1-20 parts of other functional additives. The specific operation is as follows: Copolymerized polypropylene, glycidyl methacrylate (ether), and stabilizer are compounded and granulated in a parallel twin-screw extruder. Carboxyl, or hydroxyl, or amino long-chain copolymers at the end are used as chain extenders and other functional additives, re-extruded by twin-screws, water-cooled strands are cut into pellets, and after drying, they are foamed by physical foaming agent batch method Finally, a kind of expanded polypropylene beads (EPP) with high melt strength can be obtained. The preferred dosage of random polypropylene powder is 75-95 parts; the dosage of glycidyl methacrylate (ether) is 4-15 parts, the stabilizer is 0.05-2 parts; the dosage of chain extender is 1-10 parts; the dosage of other functional additives is 3 parts -15 copies.

2. According to the present invention, the random polypropylene with a melting point lower than 150°C is a random polypropylene, which is a blend of one or more of the binary or terpolymers of propylene, ethylene, and 1-butene , the molecular weight distribution of the copolymer is Mw/Mn=2-20, and the melt flow index (190°C, 2.16Kg) is 1-15g/10min. The atactic polypropylene having a melting point below 150°C is preferably a combination of random polypropylenes having a melting point below 140°C.

3. The high-energy rays of the present invention are high-energy electron rays produced by industrial electron accelerators or gamma rays produced by 60Co sources, and the radiation dose is preferably 3～8KGry

4. The antioxidant described in the present invention is at least one of the antioxidants 168, 1010, 1076, and 626, preferably in an amount of 0.01-0.5 parts.

5. The carboxyl, or hydroxyl, or amine-based long-chain copolymer described in the preparation method of high-strength expanded polypropylene beads (EPP) described in the present invention is used as a chain extender, and its structure For compositions containing single or two or more carboxyl, or hydroxyl, or amine functional groups or these functional groups, the preferred dosage is 2-10 parts.

6. The functional auxiliary agent described in the present invention is one or more of foaming nucleating agent, antioxidant, antistatic agent, flame retardant, color masterbatch, coupling agent, and the preferred auxiliary agent dosage is 4 ~10 servings.

7. The foaming nucleating agent in the functional auxiliary agent of the present invention is talcum powder, mica, glass beads, silicon dioxide, calcium carbonate, montmorillonite, kaolin, aluminum oxide, barium sulfate, zinc oxide, stearin Zinc acid, calcium stearate at least one; The antistatic agent is alkyl imidazolines, quaternary phosphorus salts, quaternary sulfur salts, quaternary ammonium salts, alkyl sulfonates or phosphates ; The flame retardant is one or more of magnesium hydroxide, aluminum hydroxide, zinc borate, intumescent flame retardant DTPB; the coupling agent is a silane coupling agent, a titanate coupling agent, One or more of the aluminate coupling agents.

8 The present invention comprises the following steps:

(1) Copolymerized polypropylene, glycidyl methacrylate (ether), and stabilizer are mixed uniformly by a high-speed mixer, then added to a parallel twin-screw extruder for compounding and granulation, and after drying, they are irradiated with high-energy electron rays , then add long-chain copolymers with carboxyl groups, or hydroxyl groups, or amino groups at the end as chain extenders and other functional additives. 2mm, small modified polypropylene particles with a diameter of 0.5-2mm;

(2) Put polypropylene particles, dispersant, and water into the autoclave, inject the physical foaming agent into the autoclave under stirring conditions, and raise the temperature of the autoclave to 120-160°C at the same time, the pressure rises As high as 2.0-8.0MPa, after reaching the set temperature and pressure, keep it for 20-60 minutes, so that the foaming agent can penetrate into the polypropylene particles;

(3) The controllable pressure release of the autoclave, the polypropylene particle-high pressure water dispersion mixture material is sprayed into the cold water cooling system, and the polypropylene foam beads with a foaming ratio of 2-30 times are obtained; The foaming ratio of polypropylene foamed beads needs to be initially obtained in the secondary foaming device, in a water vapor atmosphere, control the pressure of 0.1-1.5MPa, keep it for 10-60s, release the pressure, Further obtain higher expansion ratio polypropylene foam beads, the expansion ratio is 15 to 60 times.

(4) Prepare polypropylene foam beads and dry them in an environment of 30-60°C for 10-48 hours, inject the dried polypropylene foam beads into steam compression molding equipment, and heat and cool them with water vapor to obtain polypropylene foam beads. Acrylic foam bead molding.

9. The dispersant of the present invention is one or more of kaolin, sodium dodecyl sulfonate, aluminum sulfate, calcium carbonate, barium sulfate, and aluminosilicate.

10. The physical foaming agent described in the present invention is one or both of carbon dioxide and nitrogen.

11. The pressure release rate of the autoclave according to the present invention is 0.3-2.0 MPa/s, and the cooling rate of the polypropylene particle-water dispersion mixture is 20-40° C./s.

Detailed ways

Example 1

(1) 300g of copolymerized polypropylene, 4g of octadecyl glycidyl methacrylate, and 0.6g of stabilizer 1010 were mixed uniformly by a high-speed mixer and then added to a parallel twin-screw extruder for compounding and granulation. After drying After irradiating with 3.5KGry high-energy electron rays, add 4g of functional additives and blend them with a high-speed mixer, then add twin-screws to re-extrude water-cooled strands and pelletize to obtain small modified polypropylene particles with a length of 1.5mm and a diameter of 1.2mm ;

(2) Put polypropylene particles, dispersant, and water into the autoclave, inject the physical foaming agent into the autoclave under stirring conditions, and raise the temperature of the autoclave to 130°C and the pressure to 3MPa, after reaching the set temperature and pressure, keep it for 30min to make the foaming agent penetrate into the polypropylene particles;

(3) The pressure release of the autoclave is controlled, and the polypropylene particle-high pressure water dispersion mixture is sprayed into the cold water cooling system to obtain polypropylene foam beads with a foaming ratio of 13 times, and the initially obtained polypropylene foam The beads are in the secondary foaming device, in the water vapor atmosphere, control the pressure of 0.1-1.5MPa, keep it for 25s, release the pressure, and further obtain a higher expansion ratio of polypropylene foam beads, the expansion ratio is 35 times .

(4) Prepare polypropylene foam beads and dry them at 50°C for 10 hours, inject the dried polypropylene foam beads into steam compression molding equipment, and heat and cool them with water vapor to obtain polypropylene foam beads pellet shaped body.

Example 2

(1), 300g of copolymerized polypropylene, 7g of glycidyl methacrylate, stabilizer 1010 0.6g, 168 0.3g are mixed uniformly by a high mixer, then added to a parallel twin-screw extruder for compounding and granulation, after drying, After irradiating 6.0KGry high-energy electron rays, add 2g of chain extender bisphenol A, 4g of functional additives after blending in a high-speed mixer, add twin-screws to re-extrude water-cooled strands and pelletize them to obtain 1.5mm in length and 1.2 in diameter Modified polypropylene small particles;

(2) Put polypropylene particles, dispersant, and water into the autoclave, inject the physical foaming agent into the autoclave under stirring conditions, and raise the temperature of the autoclave to 126°C and the pressure to 2.5MPa, after reaching the set temperature and pressure, keep it for 30 minutes to make the foaming agent penetrate into the polypropylene particles;

(3) The pressure release of the autoclave is controlled, and the polypropylene particle-high pressure water dispersion mixture is sprayed into the cold water cooling system to obtain polypropylene foam beads with an expansion ratio of 11 times.

Example 3

(1) Mix 300g of polypropylene copolymer, 2g of octadecyl glycidyl methacrylate, and 0.6g of stabilizer 1010 into a parallel twin-screw extruder for compounding and granulation, after drying After being irradiated by 7.5KGry high-energy electron rays, 1.5g of ethylenediamine and 4g of functional additives were blended by a high-speed mixer, and then added into twin-screws to re-extrude water-cooled strands and pelletize them to obtain 1.5mm in length and 1.2 in diameter. Modified polypropylene small particles;

(2) Put polypropylene particles, dispersant, and water into the autoclave, inject the physical foaming agent into the autoclave under stirring conditions, and raise the temperature of the autoclave to 130°C and the pressure to 3MPa, after reaching the set temperature and pressure, keep it for 30min to make the foaming agent penetrate into the polypropylene particles;

(3) The pressure release of the autoclave is controlled, and the polypropylene particle-high pressure water dispersion mixture is sprayed into the cold water cooling system to obtain polypropylene foam beads with a foaming ratio of 13 times, and the initially obtained polypropylene foam The beads are in the secondary foaming device, in a water vapor atmosphere, the pressure is controlled at 0.8MPa, kept for 25s, and the pressure is released to further obtain higher expansion ratio polypropylene foam beads, the expansion ratio is 41 times.

(4) Prepare polypropylene foam beads and dry them at 50°C for 10 hours, inject the dried polypropylene foam beads into steam compression molding equipment, and heat and cool them with water vapor to obtain polypropylene foam beads pellet shaped body.

Example 4

(1) Mix 300g of polypropylene copolymer, 12g of octadecyl glycidyl methacrylate, and 0.6g of stabilizer 1010, mix them uniformly in a high-speed mixer, and then add them to a parallel twin-screw extruder for compounding and granulation. After drying After being irradiated with 5KGry high-energy electron rays, 1g of chain extender 593 was added, and 4g of functional additives were blended by a high-speed mixer, and twin-screws were added to re-extrude water-cooled strands and pelletized to obtain a modified 1.5mm in length and 1.2 in diameter. Non-toxic polypropylene small particles;

(2) Put polypropylene particles, dispersant, and water into the autoclave, inject the physical foaming agent into the autoclave under stirring conditions, and raise the temperature of the autoclave to 130°C and the pressure to 3MPa, after reaching the set temperature and pressure, keep it for 30min to make the foaming agent penetrate into the polypropylene particles;

(3) The pressure release of the autoclave is controlled, and the polypropylene particle-high pressure water dispersion mixture is sprayed into the cold water cooling system to obtain polypropylene foam beads with a foaming ratio of 9 times, and the initially obtained polypropylene is foamed In the secondary foaming device, in the water vapor atmosphere, the pressure is controlled at 1.2MPa, kept for 25s, and the pressure is released to further obtain polypropylene foamed beads with a higher expansion ratio, and the expansion ratio is 37 times.

(4) Prepare polypropylene foam beads and dry them at 50°C for 10 hours, inject the dried polypropylene foam beads into steam compression molding equipment, and heat and cool them with water vapor to obtain polypropylene foam beads pellet shaped body.

Claims (11)

1. A preparation method for preparing high-strength expanded polypropylene beads (EPP) with low irradiation intensity, characterized in that: its formula is as follows: 50-95 parts of random polypropylene powder consumption; glycidyl methacrylate (Ether) 2-20 parts, stabilizer 0.005-5 parts; chain extender 1-15 parts; other functional additives 1-20 parts. The specific operation is as follows: Copolymerized polypropylene, glycidyl methacrylate (ether), and stabilizer are compounded and granulated in a parallel twin-screw extruder. Carboxyl, or hydroxyl, or amino long-chain copolymers at the end are used as chain extenders and other functional additives, re-extruded by twin-screws, water-cooled strands are cut into pellets, and after drying, they are foamed by physical foaming agent batch method Finally, a kind of expanded polypropylene beads (EPP) with high melt strength can be obtained. 2. according to claim 1, a kind of low irradiation intensity prepares the random polypropylene in the preparation method of high-strength expanded polypropylene beads (EPP), it is characterized in that: the random polypropylene powder is atactic Polypropylene is a blend of one or more of the binary or terpolymers of propylene, ethylene, and 1-butene. The molecular weight distribution of the copolymer is Mw/Mn=2-20, and the melt flow index (190°C, 2.16 Kg) 1 ~ 15g/10min. 3. a kind of preparation method of low irradiation intensity according to claim 1 prepares high-strength expanded polypropylene beads (EPP), it is characterized in that: described high-energy ray is the high-energy electron ray that industrial electron accelerator produces or Gamma rays produced by 60Co sources. 4. a kind of preparation method of low irradiation intensity according to claim 1 prepares high-strength expanded polypropylene beads (EPP), it is characterized in that, described antioxidant is antioxidant 168,1010,1076, At least one of 626. 5. a kind of low irradiation intensity according to claim 1 prepares in the preparation method of high-strength expanded polypropylene beads (EPP), it is characterized in that, described terminal band monofunctional carboxyl group, or hydroxyl group or amine Substances with a long-chain structure or carboxyl groups with two or more functional groups, or hydroxyl groups, or amine-based substances can be used as chain extenders, and can be a combination of these chain extenders. 6. a kind of low irradiation intensity according to claim 1 prepares in the preparation method of high-strength expanded polypropylene beads (EPP), it is characterized in that, described functional auxiliary agent is foaming nucleating agent, antioxidant One or more of antistatic agents, flame retardants, masterbatches, and coupling agents. The amount of additives is 2 to 15 parts. 7. a kind of low irradiation intensity according to claim 1 prepares in the preparation method of high-strength expanded polypropylene beads (EPP), it is characterized in that, the foaming nucleation in the auxiliary agent described in claim 5 The agent is at least one of talcum powder, mica, glass beads, silicon dioxide, calcium carbonate, montmorillonite, kaolin, aluminum oxide, barium sulfate, zinc oxide, zinc stearate, calcium stearate; The electrostatic agent is alkyl imidazoline, quaternary phosphorus salt, quaternary sulfur salt, quaternary ammonium salt, alkyl sulfonate or phosphate; the flame retardant is magnesium hydroxide, aluminum hydroxide, boric acid One or more of zinc and intumescent flame retardant DTPB; the coupling agent is one or more of silane coupling agent, titanate coupling agent, and aluminate coupling agent. 8. a kind of low irradiation intensity according to claim 1 prepares in the preparation method of high-strength expanded polypropylene beads (EPP), it is characterized in that, comprises the following steps: (1) Copolymerized polypropylene, glycidyl methacrylate (ether), and stabilizer are mixed uniformly by a high-speed mixer, then added to a parallel twin-screw extruder for compounding and granulation, and after drying, they are irradiated with high-energy electron rays , then add long-chain copolymers with carboxyl groups, or hydroxyl groups, or amino groups at the end as chain extenders and other functional additives. 2mm, small modified polypropylene particles with a diameter of 0.5-2mm; (2) Put polypropylene particles, dispersant, and water into the autoclave, inject the physical foaming agent into the autoclave under stirring conditions, and raise the temperature of the autoclave to 120-160°C at the same time, the pressure rises As high as 2.0-8.0MPa, after reaching the set temperature and pressure, keep it for 20-60 minutes, so that the foaming agent can penetrate into the polypropylene particles; (3) The controllable pressure release of the autoclave, the polypropylene particle-high pressure water dispersion mixture material is sprayed into the cold water cooling system, and the polypropylene foam beads with a foaming ratio of 2-30 times are obtained; The foaming ratio of polypropylene foamed beads needs to be initially obtained in the secondary foaming device, in a water vapor atmosphere, control the pressure of 0.1-1.5MPa, keep it for 10-60s, release the pressure, Further obtain higher expansion ratio polypropylene foam beads, the expansion ratio is 15 to 60 times. (4) Prepare polypropylene foam beads and dry them in an environment of 30-60°C for 10-48 hours, inject the dried polypropylene foam beads into steam compression molding equipment, and heat and cool them with water vapor to obtain polypropylene foam beads. Acrylic foam bead molding. 9. The method according to claim 7, characterized in that, the dispersant is one or both of kaolin, sodium lauryl sulfonate, aluminum sulfate, calcium carbonate, barium sulfate, aluminosilicate above. 10. The method according to claim 7, characterized in that, the physical blowing agent is one or both of carbon dioxide and nitrogen. 11. The method according to claim 7, characterized in that, in step (4), the pressure release rate of the autoclave is 0.3 to 2.0 MPa/s, and the cooling rate of the polypropylene particle-water dispersion mixture is 20 to 40 °C/s.