CN1226339C - In situ modified waste rubber powder composite material and preparing method thereof - Google Patents

Abstract

The present invention relates to in-situ modified waste rubber powder composite materials and a preparing method thereof. In the preparing method, waste rubber powders on which common mechanical disintegration is carried out are directly added to different rubber or various thermoplastics through a common rubber plastic processing technology and devices while surface pretreatment is not carried out on the waste rubber powders, and the rubber powders and the rubber or the plastics are modified in situ to form a tight combination through a special conjugation three-component interpenetrating polymer network and an interface conjugation interpenetrating technology; therefore, vulcanized rubber or thermoplasticity elastic body materials with good performance are obtained. The present invention has the advantages of simple technology, low cost and good performance. The in-situ modified waste rubber powder composite materials can be applied to the production of various vulcanization rubber products or thermoplasticity elastic body products and have the application fields of tyres, shoe manufacture, construction materials, automobile fittings, other industrial and domestic rubber products, etc. The present invention has a wide application prospect.

Description

In-situ modified waste rubber powder composite material and preparation method thereof

(1) Technical field

The invention relates to the field of environmental materials, in particular to an in-situ modified waste rubber powder composite material and a preparation method thereof.

(2) Background technology

Human society is currently facing serious environmental problems, one of which is the disposal of solid waste. With the rapid development of the global automobile industry, the tire industry has advanced by leaps and bounds. At the same time, it has also caused the accumulation of a large number of waste tires, together with other waste rubber products, forming a serious "black pollution". Waste rubber is mainly composed of cross-linked polymers that are not easy to recycle and reuse. How to deal with these waste rubbers has become an increasingly urgent worldwide problem. The amount of waste rubber produced in the world every year is at least 12 million tons, of which 60-70% are waste tires. In 2000, there were about 800 million scrapped tires in the world, and there were 250 million tires in the United States alone, of which only 15-20% were recycled. With the further development of the world economy, especially the automobile industry, the pressure on waste rubber will also increase.

The ways to process and recycle waste rubber include the production of reclaimed rubber, thermal cracking, and the production of rubber powder. The traditional reclaimed rubber production process will cause serious secondary environmental pollution. At the same time, the product performance is poor and economically unreasonable. Therefore, the production of reclaimed rubber has declined sharply in recent years. There are also environmental and economical rationality issues in waste rubber thermal cracking to recover organic matter and heat energy. Compared with reclaimed rubber, the process of producing rubber powder from waste rubber is simple, the production process consumes less energy, does not discharge waste water, waste gas pollutes the environment, and the rubber powder has excellent performance and wide range of uses. It is an effective product integrating environmental protection and resource regeneration. Promising methods of processing and recycling waste rubber.

Rubber powder has a wide range of uses. It can be mixed with asphalt for road paving materials, can also be mixed into rubber formulations to make various rubber products, and can also be blended with thermoplastic resins to make toughened plastics or thermoplastic elastomers. In many countries, the production and utilization of rubber powder largely depend on the waste rubber freezing and crushing process. The fine rubber powder (above 100 mesh) frozen and crushed by liquid nitrogen can be directly added to the rubber formula, or directly mixed with plastics. mix. This fine rubber powder has a high cost and is difficult to popularize and apply. Another method is to use mechanically pulverized ordinary rubber powder after surface pretreatment (activation) and then add it to rubber or plastics. Although the cost of this rubber powder pretreatment method is lower than that of the freezing pulverization method, it still increases the complexity of the process. , and will cause new environmental pollution.

Blending rubber powder with rubber to make vulcanized rubber, or blending with thermoplastics to make thermoplastic elastomers, the key is to achieve a tight bond between the rubber powder particles and the rubber or plastic matrix. Because it is often difficult to achieve a firm bond between the rubber powder and the rubber matrix or thermoplastic resin matrix, the mechanical properties of the resulting blend are not good. In order to solve this problem, compatibilizers or interface modifiers must be added to the system to improve the interfacial bonding strength between rubber powder and rubber or thermoplastic resin. Since rubber powder is a cross-linked polymer particle, its blending with linear rubber or plastic molecular chains is different from the usual blending of two linear polymers, so the commonly used block copolymer or graft copolymerization Physical compatibilizers are not applicable.

Jia Demin, one of the inventors of the present application, proposed the new concept of conjugated three-component interpenetrating polymer network and interfacial conjugated interpenetration in the early 1990s, wherein one polymer component is used as a public network and the other two are different from each other. The interpenetrating but closely contacting polymer network interpenetrates and entangles, respectively, so that the latter two polymer components are tightly bound together and the performance of the entire three-component polymer system is significantly improved, showing a clear synergy . In the system, the interface between the two polymers is mainly connected together by the molecular chain of the third polymer as the public network crossing the interface and forming an IPN structure with the two polymers respectively. It is called interfacial conjugate interpenetration for short. Guided by this new concept, Jia Demin and others prepared polyurethane/poly(styrene-co-divinylbenzene)/waste rubber powder, polyurethane/poly(methyl methacrylate-co-ethylene glycol dimethacrylate) The two composite systems of waste rubber powder and waste rubber powder have obtained a good synergy in performance and opened up a new way for the utilization of rubber powder. However, due to the high cost of polyurethane, the performance cannot meet the requirements of most rubber products including tires. It is necessary to develop rubber-powder-containing composite materials based on general-purpose rubber or thermoplastics to broaden the scope of this rubber powder. new method of utilization.

(3) Contents of the invention

The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, and propose a new type of in-situ modified waste rubber with rubber powder as the dispersed phase, ordinary rubber or thermoplastic resin as the matrix, and the interface forming a conjugated interpenetrating network. The preparation method of powder composite material opens up a wider way for the utilization of rubber powder.

The purpose of the present invention is also to provide the in-situ modified waste rubber powder composite material prepared by the method.

The preparation method of in-situ modified waste rubber powder composite material of the present invention comprises the following steps:

The first step is to mix the rubber powder, rubber or thermoplastic resin, interface modifier, initiator and other compounding ingredients evenly in an open mixer, internal mixer or extruder;

The second step is to obtain vulcanized rubber products through vulcanization and interfacial in-situ reaction of the rubber compound with rubber as the matrix at a vulcanization temperature of 100-200 ° C. The thermoplastic resin-based compound is extruded at a resin processing temperature of 100-250 ° C. Machine or injection machine reaction molding into thermoplastic elastomer products; the interface modifier includes acrylic acid, acrylate, methacrylic acid, methacrylate, styrene, α-methylstyrene, divinylbenzene, maleic acid Acid anhydride and its ester, fumaric anhydride and its ester, acrylonitrile, acrylamide, N-methylolacrylamide, vinyl acetate, N-vinylpyridine monomer, N-vinylpyrrolidone, triallyl iso One or more mixtures of cyanurates;

The weight ratio of the raw materials is as follows: 100 parts of rubber or thermoplastic, 5-300 parts of rubber powder, 1-30 parts of interface modifier, 0.05-2 parts of initiator, and other compounding agents in usual amounts.

The rubber refers to one or more mixtures of natural rubber and various synthetic rubbers, and thermoplastics include one or more of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and polypropylene mixture.

The rubber powder is mechanically pulverized rubber powder without surface pretreatment or activation, with a fineness of 20-100 mesh.

The initiator is one or more mixtures of dicumyl peroxide, benzoyl peroxide, tert-butyl benzoyl peroxide, di-tert-butyl peroxide, redox system containing peroxide.

In the above system, rubber powder and rubber or thermoplastic are mixed and contacted uniformly through kneading, while modifier monomers, initiators and various additives are uniformly dispersed in the rubber or thermoplastic matrix. Then, during vulcanization or high-temperature processing and molding, the interfacial modifier on the one hand polymerizes in situ in the matrix to form interpenetrating polymer networks and grafts with the matrix polymer; on the other hand, it diffuses and penetrates into the surface layer of rubber powder particles. And in situ polymerization under the action of the initiator, and form another interpenetrating polymer network with the cross-linked polymer in the rubber powder, so that the modifier becomes a public network after polymerization, and an interface network occurs with the matrix polymer and the rubber powder at the same time Conjugated interpenetrating, the whole system becomes a conjugated three-component interpenetrating polymer network. The mechanical properties of the composite system are significantly improved due to the tight combination formed in the interfacial region.

The in-situ modified waste rubber powder composite material prepared by the present invention can be applied to manufacture various vulcanized rubber products or thermoplastic elastomer products, and its application fields include tires, shoemaking, auto parts, building materials and other industrial and civilian rubber products, etc. occasions, has broad application prospects.

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

(1) Using special conjugated three-component interpenetrating polymer network and interface conjugated interpenetrating modification technology, the interface between waste rubber powder and rubber or plastic can be modified in situ, and tightly combined into vulcanized rubber products or thermoplastics with excellent performance. Elastomer composites.

(2) Utilize 20-100 mesh non-frozen crushed ordinary rubber powder, avoiding liquid nitrogen or other expensive equipment for frozen crushing and huge energy consumption, low cost of rubber powder, and easy source;

(3) The rubber powder does not require surface pretreatment or activation, which not only simplifies the process and equipment for rubber powder utilization, reduces costs, but also further reduces environmental pollution.

(4) General rubber and plastic processing technology and equipment can be used without adding new equipment, and it is easy to popularize and apply.

(5) The rubber powder content in the composite material is high, up to 50-75%.

(6) The mechanical properties of composite vulcanized rubber or thermoplastic elastomer materials are better than those of general vulcanized rubber containing rubber powder.

(7) The product has broad application prospects and significant social and economic benefits.

(4) Specific implementation methods

Below in conjunction with embodiment, the present invention will be further described.

Example 1

The first step is to masticate the natural rubber at room temperature on the open mill, and then add tire rubber powder for mixing. The mass ratio of the two is 100/0-50/50. At the same time, add modifiers maleic anhydride and octadecyl methacrylate 10 parts of base ester and ethylene glycol dimethacrylate three monomers (mass ratio 1:1:0.1) and 0.5 part of benzoyl peroxide (BPO), then add stearic acid and zinc oxide according to the formula in Table 1 , Accelerator M and sulfur and other compounding agents, mixed evenly to produce tablets;

The second step is to park the mixed rubber at room temperature overnight, and measure the positive vulcanization time with a vulcanizer at a temperature of 143°C, and then perform molding vulcanization on a flat vulcanizer to obtain an in-situ modified natural rubber/rubber powder compound Material vulcanized rubber test piece.

The physical and mechanical properties test results in Table 1 show that the performance of the in-situ modified natural rubber/rubber powder composite vulcanizate is significantly better than that of the natural rubber/rubber powder vulcanizate without interface modification.

Table 1 Physical and mechanical properties of in-situ modified natural rubber/rubber powder composite vulcanizate natural rubber Natural Rubber/Powder Natural rubber/modifier/rubber powder Powder content, wt% 0 5 10 20 30 50 5 10 20 30 50 Tensile strength, MPa 16.0 14.8 14.3 12.5 11.6 8.5 21.0 24.5 20.9 18.8 13.5 Elongation at break,% 810 740 700 650 640 550 550 580 500 460 380 Permanent deformation, % 12 10 10 12 12 10 9 12 12 12 8

Note: (1) Mixed rubber formula: natural rubber 100, zinc oxide 6, sulfur 3.5, stearic acid 0.5, accelerator M 0.5. The vulcanization condition is 143°C×T90.

Example 2

The first step is to add 100 parts of styrene-butadiene rubber to the open mill and add 50 parts of tire rubber powder to mix at room temperature. 3: 0.2 weight mixed mixture, initiator dicumyl peroxide 0.2 parts, then add 1 part of stearic acid, 3 parts of zinc oxide, 1 part of accelerator CZ, 1.8 parts of sulfur and 40 parts of N330 carbon black, mixing Uniform film;

The second step is to park the mixed rubber at room temperature overnight, and measure the positive curing time with a vulcanizer at a temperature of 151 ° C, and then carry out molding vulcanization on a flat vulcanizing machine to obtain the vulcanization of the in-situ modified styrene-butadiene rubber/rubber powder composite material glue.

The 300% modulus stress, tensile strength, elongation at break and tensile permanent deformation of the composite vulcanizate are 12.6MPa, 21.5MPa, 500% and 12% respectively, without adding rubber powder and modifier The corresponding values of styrene-butadiene rubber vulcanizate are 8.0MPa, 20.5MPa, 520% and 10% respectively.

Example 3

The first step: 100 parts of EPDM rubber, 50 parts of 60-mesh rubber powder, 6 parts of butyl methacrylate, 3.0 parts of glycidyl methacrylate monomer, 3.0 parts of triallyl isocyanurate, 5.0 parts of dicumyl peroxide, then add 5 parts of zinc oxide, 1 part of stearic acid, 1 part of anti-aging agent RD, 1 part of anti-aging agent MB, 5.0 parts of paraffin oil, 50 parts of carbon black. Mix evenly at room temperature on the mixer.

The second step is to park the mixed rubber at room temperature overnight, then measure the vulcanization time with a vulcanizer at 160°C, and finally carry out molding vulcanization on a flat vulcanizer to obtain a vulcanized rubber test piece.

The 200% modulus stress, tensile strength, elongation at break, tensile permanent deformation and hardness of the vulcanized rubber are 7.8MPa, 16.2MPa, 400%, 10% and 72 (Shore A, degree), respectively. The corresponding properties of the EPDM vulcanizate without rubber powder and modifier are 5.5MPa, 19.3MPa, 385%, 8% and 68 (Shore A, degree).

Example 4

In the first step, 70 parts of 80-mesh tire rubber powder and 30 parts of linear low-density polyethylene (LLDPE) resin, 5 parts of LLDPE and maleic anhydride/methyl methacrylate/butyl acrylate three monomer grafts, methyl Put 5 parts of glycidyl acrylate and 1 part of trimethylolpropane trimethacrylate into an open mixer or internal mixer, heat to about 120°C and mix evenly for 10 minutes, or put into a twin-screw extruder Mixing, extruding and pelletizing in the range of 110-160°C in the machine.

The second step: The blend mixed on the open mill or internal mixer is hot-pressed on a 150-160°C electric heating plate vulcanizer, and cooled and shaped under pressure; the pellets obtained from the twin-screw extruder can be used Injection or extrusion.

The physical and mechanical properties of the thermoplastic elastomer obtained in this example: tensile strength 8.8MPa, elongation at break 280%, tensile permanent deformation 25%, Shore A hardness 83, melt index 1.2g/10min.

Claims (5)

1, a kind of preparation method of in-situ modification waste rubber powder composite material, comprises the steps: The first step is to mix waste rubber powder, rubber or thermoplastic resin, interface modifier, initiator and other compounding ingredients uniformly in an open mill, internal mixer or extruder; In the second step, the mixed rubber with rubber as the matrix undergoes vulcanization and interfacial in-situ reaction at a vulcanization temperature of 100-200°C to obtain vulcanized rubber products, or the mixture with thermoplastic resin as the matrix is processed at a resin processing temperature of 100-250°C. Extruder or injection machine reaction molding into thermoplastic elastomer products; The interfacial modifier includes acrylic acid, acrylate, methacrylic acid, methacrylate, styrene, α-methylstyrene, divinylbenzene, maleic anhydride and esters thereof, fumaric anhydride and esters thereof, One or more of acrylonitrile, acrylamide, N-methylolacrylamide, vinyl acetate, N-vinylpyridine monomer, N-vinylpyrrolidone, triallyl isocyanurate Mixture; the rubber includes one or more mixtures of natural rubber and various synthetic rubbers; The weight ratio of the raw materials is: 100 parts of rubber or thermoplastic resin, 5-300 parts of waste rubber powder, 1-30 parts of interface modifier, 0.05-2 parts of initiator, and other compounding agents in the usual amount. 2. The preparation method of in-situ modified waste rubber powder composite material according to claim 1, characterized in that the thermoplastic resin comprises one of high-density polyethylene, low-density polyethylene, linear low-density polyethylene and polypropylene or a mixture of more than one. 3. The preparation method of in-situ modified waste rubber powder composite material according to claim 1 or 2, characterized in that the waste rubber powder is mechanically pulverized rubber powder without surface pretreatment or activation, and the fineness is 20-100 mesh . 4, according to the preparation method of the described in-situ modified waste rubber powder composite material of claim 1 or 2, it is characterized in that, initiator is dicumyl peroxide, benzoyl peroxide, tert-butyl peroxide One or more mixtures of formyl, di-tert-butyl peroxide, and peroxide-containing redox systems. 5. The in-situ modified waste rubber powder composite material prepared by the method of claim 1.