Low-density modified elastomer material as well as preparation method and application thereof

Abstract

The invention belongs to a material modification technology, and relates to an elastomer, in particular to a low-density modified elastomer material as well as a preparation method and application thereof. The technical difficulty in the prior art is that a core-shell polymer foaming agent is uniformly added into dense modified rubber, so that the dense modified rubber expands when heated to reduce the particle density to obtain a foamed elastomer, although the density is reduced, the cross section is gradually enlarged in the production process when the foaming elastomer is applied to a production end, and the density of a finished product is increased and even reaches 0.81. The characteristics of a sectional control process are mainly utilized, after dynamic vulcanization of the modified rubber, the polymer microspheres are uniformly distributed in the modified rubber, and in the extrusion molding process of an application end, the prepared product achieves the appearance shape of the sealing strip of the automobile part, and has the same physical properties as dense modified rubber and the effect of light weight at the same time.

Description

Technical Field

[0001] The invention belongs to material modification technology and relates to an elastomer, specifically a low-density modified elastomer material and a preparation method and application thereof. Background Art

[0002] At present, most of the materials for automobile soft rubber parts are extruded by dense materials. With the development of automobile lightweight, the application research of foamed composite materials in automobile door and window sealing strips has attracted more and more attention due to its light weight. Automobile sealing strips with dense modified plastic materials as the main body and other thermoplastic elastomers as auxiliary materials are assembled on the car for sealing, dustproof, waterproof and sound insulation. The existing technology mixes EPDM rubber, recycled polypropylene and styrene rubber, grinds them to obtain mixed powder; mixes fillers, light stabilizers, fluorine-containing additives, mixed powders, peroxides and additives, extrude and granulate to obtain thermoplastic elastomers; homogenizes thermoplastic elastomers and expandable microsphere foaming agents, and then extrude them at 160-190℃ and screw speed 140-160rpm to obtain foamed TPV materials for automobile door and window sealing strips. The prior art comprises the following steps: uniformly mixing polypropylene, EPDM, POE, kaolin, a small amount of paraffin oil, an antioxidant, an ultraviolet absorber, a processing aid, and a masterbatch in a high-speed mixer, discharging the material, and then extruding and granulating the material with a twin-screw extruder for standby use; the remaining paraffin oil is injected into the extruder material in the twin-screw extruder using a weight loss scale, and the processing temperature of the twin-screw extruder is 180-210 degrees Celsius; then, the granular material produced in the previous step is uniformly mixed with a cross-linking agent and a cross-linking aid in a high-speed mixer, discharging the material, and then extruding and granulating the material with a twin-screw extruder for standby use, and the processing temperature of the twin-screw extruder is 190-220 degrees Celsius; finally, the granular material processed in the previous step is uniformly mixed with a micro-foaming agent in a high-speed mixer, and then extruded and granulated the material with a twin-screw extruder for standby use, and the processing temperature of the twin-screw extruder is 145-160 degrees Celsius.

[0003] In recent years, the application of micro-foaming technology in lightweighting has been well promoted, but the application of foamed elastomers in the field of exterior decoration, especially in automotive guide groove products, is often not ideal. In existing production, the density of foamed elastomers is about 0.7. When this material is used at the application end, the finished product is extruded through a single screw with a mold. The cross-section is enlarged in the production process, and the density of the finished product is increased to more than 0.8. Therefore, it is necessary to develop a new preparation process for foamed elastomers so that the foamed elastomer material can be well applied at the production end. Summary of the invention

[0004] The difficulty of the prior art is to uniformly add a core-shell polymer foaming agent to the dense modified rubber, so that it expands when heated to reduce the particle density to obtain a foamed elastomer. Although the density is reduced, when it is used at the production end, the cross-section magnification varies in size during the production process, and the density of the finished product is increased to 0.8 or even 0.81. The present invention mainly uses the characteristics of the segmented control process. After the dynamic vulcanization of the modified rubber, the polymer microspheres are uniformly distributed in the modified rubber. During the extrusion molding process at the application end, the prepared product achieves the appearance and shape of the automotive parts sealing strip while having the same physical properties as the dense modified rubber and a lightweight effect.

[0005] The present invention adopts the following technical scheme.

[0006] A preparation method of a low-density modified elastomer material comprises the following steps: melting and mixing polypropylene, EPDM rubber, filler oil and an auxiliary agent to obtain a master batch; then feeding the master batch and a vulcanizing agent into a twin-screw extruder, and then feeding a microsphere foaming agent into the end of the twin-screw extruder to granulate and extrude to obtain the low-density modified elastomer material.

[0007] In the present invention, each raw material is fed by a loss-in-weight scale, and the specific feeding method is conventional technology. As common sense, a twin-screw extruder is an existing device, which has a multi-stage barrel, a main feeding port is provided in the first stage barrel, and masterbatch and vulcanizing agent are fed, and an auxiliary feeding port is provided at the end (the penultimate stage or the third stage barrel), and microsphere foaming agent is fed.

[0008] Preferably, the temperature of the homogenizing section of the twin-screw extruder is 90°C to 100°C.

[0009] In the present invention, the starting temperature of the microsphere foaming agent is 160-200°C, and the maximum withstand temperature is 220-280°C. The present invention adopts the existing microsphere foaming agent combined with the elastomer formula and processing technology, solves the problem of serious environmental pollution caused by the use of chemical foaming agents and the problem that the uniformity of the use of physical foaming agents cannot be guaranteed, and the prepared particles have a low density of 0.7, especially in the extrusion molding process at the application end, while achieving the appearance shape of the sealing strip of automotive parts, it has the same physical properties as dense modified rubber and a lightweight effect.

[0010] In the present invention, twin-screw extrusion melting processing is adopted to melt and mix polypropylene, EPDM rubber, filler oil and additives to obtain masterbatch. The specific processing method is the existing technology.

[0011] In the present invention, the mass ratio of polypropylene, EPDM rubber, filler oil, additive, microsphere foaming agent and vulcanizing agent is (20-40): (25-50): (20-40): (1-5): (0.5-1.5): (0.5-1.5).

[0012] Preferably, the mass ratio of polypropylene, EPDM rubber, filler oil, additive, microsphere foaming agent and vulcanizer is (25-35): (25-30): (22-28): (2-4): (0.6-1): (0.6-0.8).

[0013] In the present invention, the flash point of the filler oil is 220-300°C.

[0014] In the present invention, the auxiliary agent includes one or more of a colorant, an antioxidant, and an anti-ultraviolet agent.

[0015] In the present invention, the vulcanizing agent is one or more of di-tert-butyl peroxide isopropylbenzene (BIBP), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (BIBP), tert-butyl peroxyisopropyl carbonate (C75), trimethylolpropane trimethacrylate, and trimethylolpropane triacrylate.

[0016] The invention discloses a low-density modified elastomer material prepared by the preparation method of the low-density modified elastomer material.

[0017] The invention discloses the application of the low-density modified elastomer material in preparing lightweight plastic parts.

[0018] The invention discloses the application of the low-density modified elastomer material in preparing lightweight automobile parts.

[0019] The invention discloses the application of the low-density modified elastomer material in preparing a lightweight automobile guide channel.

[0020] The invention discloses the application of the low-density modified elastomer material in preparing lightweight extruded parts.

[0021] An automobile component, the raw materials for preparing the component include the low-density modified elastomer material.

[0022] Specifically, the automobile component includes a guide channel for an automobile; preferably, the automobile component is prepared by extrusion molding of a raw material including the low-density modified elastomer material.

[0023] Preferably, the automobile component is prepared by extrusion molding of the low-density modified elastomer material.

[0024] The present invention adopts a microsphere foaming agent, combines an elastomer formula and a processing technology, solves the problems of serious environmental pollution caused by the use of chemical foaming agents and the inability to ensure uniformity when using physical foaming agents, and the prepared particles have a low density of 0.7. Especially in the extrusion molding process at the application end, while achieving the appearance and shape of the sealing strip of automobile parts, it has the same physical properties as dense modified rubber and a lightweight effect. The prepared automobile guide groove component has almost no weight gain, and the extrusion process is stable without any sections exceeding the tolerance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a photograph of the particles of Example 2, magnified 4.5 times.

[0026] Figure 2 This is a photo of an automobile guide channel component extruded from the particles of Example 3 at the production end.

[0027] Figure 3 This is a cross-sectional photograph of the automobile guide channel component extruded from the particles of Example 3, magnified 10 times.

[0028] Figure 4 This is a photo of the cross section of an automobile guide channel component magnified 4.5 times.

[0029] Figure 5 This is a cross-sectional photo of an existing particle extruded automobile guide channel component, magnified 10 times. DETAILED DESCRIPTION

[0030] The present invention mixes the raw materials except the vulcanizer and the microsphere foaming agent, and directly enters the twin-screw extrusion melting process, or the single materials can be added to the extruder through a loss-in-weight metering scale, and the processing aids (including carbon black masterbatch) are mixed together and added through a single loss-in-weight metering scale; the granulated particles in the above method are directly mixed with the vulcanizer and then enter the twin-screw extrusion melting process, and the microsphere foaming agent is added to the end of the twin screw (the second to last section or the third section of the barrel) through a single micro-weight loss-in-weight metering scale for granulation and extrusion. The diameter of the twin screw equipment used can be 35-90mm, the speed can be 200-1000rpm, and the temperature can be 90-220℃ for processing and granulation, and the twin screw extruder is the existing technology.

[0031] The low-density modified elastomer material disclosed in the present invention has raw materials for preparing the following components in mass ratio: the mass ratio of polypropylene, EPDM rubber, filler oil, additive, microsphere foaming agent and vulcanizing agent is (25-35): (25-30): (22-27): (2-4): (0.6-1): (0.6-0.9), preferably, the mass ratio of polypropylene, EPDM rubber, filler oil, additive, microsphere foaming agent and vulcanizing agent is (25-30): (25-30): (23-26): (2-4): (0.7-0.9): (0.7-0.8).

[0032] in: Polypropylene: PP, Shore D hardness 55D-70D, copolymer type; EPDM rubber: ENB content 3.5-5, ethylene content 30-60%, Mooney viscosity (1+4) 100℃: 40-70; Filling oil: 40℃ kinematic viscosity 200-280 mm2 / s, flash point 220-300℃; Microsphere foaming agent: starting temperature: 160-200℃, maximum withstand temperature: 220-280℃, it is the existing polymer microsphere.

[0033] The following experiments illustrate the technical progress of the present invention. The raw materials used are existing products, and the specific preparation operations and performance tests are all conventional techniques.

[0034] in: Polypropylene: 3080; EPDM rubber: 3092PM; Filling oil: KP-100B; Microsphere foaming agent: polymethyl methacrylate microspheres, particle size 15-20μm, foaming temperature around 185℃, maximum temperature around 230℃; Curing agent: 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), TMPTMA (trimethylolpropane trimethacrylate), the amount of both is the same.

[0035] Additives: carbon black masterbatch 3050E, antioxidants 1010 and 168 (the dosage of the two is the same), and anti-ultraviolet agent UV234; among the additives, the mass ratio of colorant, antioxidant, and anti-ultraviolet agent is 10:1:1.

[0036] The processing method is as follows: (1) After mixing the raw materials except the vulcanizing agent and the microsphere foaming agent, directly enter the twin-screw extruder for melting processing to prepare the masterbatch; the twin-screw equipment used has a diameter of 70 mm, a rotation speed of 500 rpm, and a temperature of 160-220°C for processing and granulation, which is a conventional process; (2) After conventional mixing, the masterbatch and the vulcanizer are directly fed into the twin-screw extruder. The microsphere foaming agent is added to the end of the twin screw (the third-to-last barrel) through a separate micro-weight loss-in-weight metering scale for granulation and extrusion. The twin-screw equipment used has a diameter of 70 mm, a rotation speed of 500 rpm, and temperatures (°C): 160, 180, 190, 195, 195, 195, 195, 195, 170, 150, 120, 95, 95, 95 (Table 1 shows the experiments corresponding to different homogenization section temperatures). The fifth to eleventh temperature zones are the vulcanization sections, and the twelfth to fourteenth temperature zones are the homogenization sections.

[0037] The formulas and properties of the embodiments and comparative examples are shown in Table 1.

[0038] Material testing methods: Density: According to ISO 1183, method A, requirement 0.7±0.01g / cm 3 .

[0039] Tensile strength: According to ISO 37, 500mm / min, required to be above 4MPa.

[0040] Elongation: According to ISO 37, 500mm / min, more than 300% is required.

[0041] Shore hardness: According to ISO 868, 15s reading, Shore A, requirement 65A-75A.

[0042] Tear strength: According to ISO 34, 500mm / min, required to be above 20KN / m.

[0043] Table 1 Examples and comparative examples formulations and properties, Kg

[0044] Figure 1 This is a photo of the particles of Example 3, magnified (4.5) times. It can be seen that the foamed particles prepared by the present invention are uniformly foamed and dispersed, with good effect. Application Examples

[0045] The low-density modified elastomer material of the invention is used in the guide channel part of an automobile, and at the customer end, a conventional automobile guide channel is prepared by adopting an existing extrusion process.

[0046] Figure 2 This is a photo of an automobile guide channel component extruded from the particles of Example 3 at the production end; Figure 3 This is a cross-sectional photo of the automobile guide channel component projected at 10 times magnification; Figure 4 This is a photo of the cross section of a car guide channel component magnified 4.5 times. Figure 3 The red frame part.

[0047] As a comparison, the commercially available foamed elastomer (density 0.702) used in the extrusion of automobile guide groove parts has the phenomenon of being larger or smaller when the cross section is enlarged (magnified 10 times on a projector, the part is out of tolerance, see Figure 5 ), and the finished product density is increased to 0.81 g / cm 3 .

[0048] After quality inspection, the automobile guide groove parts extruded from the low-density modified elastomer material in Example 3 at the production end meet the requirements, and there is no phenomenon of large or small cross-section enlargement during extrusion (magnified 10 times on the projector, it does not exceed the tolerance range), and the finished product density is 0.712 g / cm 3 This solves the problem of the cross-section being sometimes larger and sometimes smaller during the production of existing foam particles, and the density of the finished product is increased to 0.81 g / cm 3 problem.

[0049] The automobile guide groove parts extruded from the particles of other embodiments meet the requirements and are within the tolerance range, but are slightly larger than those of embodiment 3. The density of the extruded parts is 0.72 g / cm 3 Inside.

[0050] When the particles of comparative example 2 were extruded into automobile guide groove parts at the production end, the size showed obvious deviation, far exceeding the tolerance range, and could not be used. Example 6

[0051] On the basis of Example 3, the temperature of the homogenizing section was adjusted to 110°C, and the rest was the same. After the granulated product was extruded into the automobile guide groove component at the production end, it was magnified 10 times on the projector, and there was a phenomenon of partial deviation from the tolerance range.

[0052] The control example adopts the formula of Example 3, and the processing method is as follows: (1) After mixing the raw materials except the vulcanizing agent and the microsphere foaming agent, directly enter the twin-screw extruder for melting processing to prepare the masterbatch; the twin-screw equipment used has a diameter of 70 mm, a rotation speed of 500 rpm, and a temperature of 160-220°C for processing and granulation, which is a conventional process; (2) After the masterbatch and the vulcanizer are conventionally mixed, they are directly put into a twin-screw extruder for melting and granulation to obtain an elastomer; after the raw materials except the vulcanizer and the microsphere foaming agent are mixed, they are directly put into a twin-screw extruder for melting and granulation to prepare the masterbatch; the twin-screw equipment used has a diameter of 70 mm, a rotation speed of 500 rpm, and a temperature of 160-220°C for processing and granulation, which is a conventional process; (3) After the elastomer and the microsphere foaming agent are conventionally mixed, they are directly subjected to twin-screw extrusion melting processing and granulation extrusion; after the raw materials except the vulcanizer and the microsphere foaming agent are mixed, they are directly subjected to twin-screw extrusion melting processing to prepare masterbatch; the twin-screw equipment used has a diameter of 70 mm, a rotation speed of 500 rpm, and a temperature of 130-180°C for processing and granulation.

[0053] The control example granulation product was extruded into automobile guide groove parts at the production end and magnified 10 times on a projector, and some parts were out of tolerance.

[0054] The present invention can realize the uniformity of dynamic vulcanization and microsphere foaming melt blending, reduce the density, and when applied at the production end, the cross-section enlargement in the production process does not have the phenomenon of sometimes large and sometimes small, and the finished product density is maintained at 0.72g / cm 3 The present invention mainly utilizes the characteristics of the segmented control process. After the dynamic vulcanization of the modified rubber, the polymer microspheres are evenly distributed in the modified rubber. During the extrusion molding process at the application end, the prepared product achieves the appearance and shape of the sealing strip of automotive parts while having the same physical properties as the dense modified rubber and a lightweight effect. In addition, the process flow is simple, the efficiency is high, and the processing cost is low.

Claims

1. A method for preparing a low-density modified elastomer material, comprising the following steps: melt-mixing polypropylene, EPDM rubber, filler oil and an additive to obtain a masterbatch; then feeding the masterbatch and a vulcanizing agent into a twin-screw extruder, and then feeding a microsphere foaming agent into the end of the twin-screw extruder, and granulating and extruding to obtain the low-density modified elastomer material.

2. The method for preparing the low-density modified elastomer material according to claim 1, characterized in that: The end is the penultimate or third barrel of the twin-screw extruder.

3. The method for preparing the low-density modified elastomer material according to claim 1, characterized in that: The temperature of the homogenizing section of the twin-screw extruder is 90°C to 100°C.

4. The method for preparing the low-density modified elastomer material according to claim 1, characterized in that: The mass ratio of polypropylene, EPDM rubber, filler oil, additive, microsphere foaming agent and vulcanizing agent is (20-40): (25-50): (20-40): (1-5): (0.5-1.5): (0.5-1.5).

5. The method for preparing the low-density modified elastomer material according to claim 1, characterized in that: The auxiliary agent includes one or more of a colorant, an antioxidant, and an anti-ultraviolet agent; the vulcanizing agent is one or more of di-tert-butyl peroxide isopropylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl peroxyisopropyl carbonate, trimethylolpropane trimethacrylate, and trimethylolpropane triacrylate.

6. The low-density modified elastomeric material prepared by the method for preparing the low-density modified elastomeric material according to claim 1.

7. Use of the low-density modified elastomeric material according to claim 6 in the preparation of lightweight plastic parts.

8. Use of the low-density modified elastomeric material according to claim 6 in the preparation of lightweight automobile parts.

9. Use of the low-density modified elastomer material according to claim 6 in preparing lightweight automobile guide channels.

10. An automobile component, the raw materials for its preparation include the low-density modified elastomer material according to claim 6.

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