PP / EPDM (polypropylene / ethylene-propylene-diene monomer) material for metal framework coating-free bonding type sealing strip and preparation method of PP / EPDM material

Abstract

The invention belongs to a material improvement technology, and relates to an automobile sealing strip material, in particular to a PP (polypropylene) and EPDM (ethylene-propylene-diene monomer) material for a sealing strip and a preparation method of the PP and EPDM material, and the PP and EPDM material can be effectively bonded with a metal framework under the condition that an adhesive is not brushed. In the prior art, when a PP + EPDM dynamic vulcanization material is combined with a metal framework, a primer is mostly needed, and the adhesion of the PP + EPDM dynamic vulcanization material and the metal framework can be increased only after the surface of stainless steel is coated with an adhesive and baked, so that the problems that the process complexity of product forming is increased, the VOC emission of an automobile sealing strip product is increased and the like exist. The PP + EPDM material for the sealing strip is prepared by developing new components from the formula, and can be effectively bonded with a metal framework under the condition that an adhesive is not brushed. When the PP / EPDM material is bonded with metal, an adhesive is not needed, good bonding force can be obtained, and the bonding strength is larger than or equal to 6 N / m under a standard test method.

Description

Technical Field

[0001] The invention belongs to material improvement technology and relates to an automobile sealing strip material, in particular to a PP+EPDM material for the sealing strip and a preparation method thereof, which can be effectively bonded to a metal frame without applying an adhesive. Background Art

[0002] The automotive sealing strip material has gone through the development process of EPDM rubber, soft PVC, and PP+EPDM dynamically vulcanized TPV materials. PP+EPDM dynamically vulcanized elastomer materials have become the star of the automotive sealing strip industry because they can be recycled and reused and are easy to process. The automotive skeleton material is usually stainless steel or hard aluminum, which has poor compatibility with PP+EPDM (PP+EPDM elastomer materials have low surface energy). It is usually necessary to brush adhesive on the stainless steel surface and bake it to increase the adhesion of the two. CN112175548A discloses that TPV has a wide range of applications, so it is often necessary to use glue to bond with metal materials. At present, TPV glue is mainly achieved by pre-treating the surface of the material with special glue. It provides a TPV that is easy to bond with glue and a method for making it. By adding EMMA (ethylene methyl methacrylate copolymer) with good compatibility with the material to the formula, and by not adding lubricants, naphthenic oil is used to further improve the bonding effect, solving the problem that TPV is difficult to bond with glue. Its products use glue to bond with metal. CN110564341B discloses that the composite obtained by compounding TPV with metal is widely used in the fields of automotive sealing strips, door and window seals, etc. At present, the adhesives used for compounding TPV with metal in China are mainly imported adhesives from Japan and Germany, and domestic adhesives have not been reported. It provides an adhesive for compounding thermoplastic elastomer with metal and a preparation method thereof. US20120110916A1 discloses an extrudable polymer for bonding metal to rubber and thermoplastic polymers, including a metal surface, a thin bonding layer of a polymer material covering at least a selected portion of the metal surface, and an elastomeric material, the elastomeric material being received on the thin bonding layer of the polymer material and exhibiting improved bonding with the metal through the thin layer of the polymer material.

[0003] The existing technology mainly uses stainless steel or aluminum strips coated with adhesives to produce sealing strips. The introduction of adhesives (glue) increases the complexity of the product molding process, increases costs, and increases the defective rate due to adhesive debugging problems, increasing VOC emissions from automotive sealing strip products. Summary of the invention

[0004] In the prior art, when combining PP+EPDM dynamically vulcanized materials with metal frames, a primer is usually required, and usually an adhesive needs to be brushed on the stainless steel surface and baked to increase the adhesion between the two. This increases the complexity of the product molding process and increases the VOC emissions of automotive sealing strip products. The present invention starts with a formula, develops a new component, and prepares a PP+EPDM material for sealing strips, which can effectively bond with metal frames without brushing adhesive.

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

[0006] A method for preparing a PP / EPDM material for a metal frame free-coating bonding type sealing strip comprises the following steps: subjecting a masterbatch particle to a vulcanizing agent for a vulcanizing reaction to obtain the PP / EPDM material for the metal frame free-coating bonding type sealing strip; the masterbatch particle comprises PP resin, EPDM rubber, operating oil, modified chlorinated polypropylene, zinc oxide, filler, additive and colorant.

[0007] In the present invention, PP resin, EPDM rubber, process oil, modified chlorinated polypropylene, zinc oxide, filler, auxiliary agent and colorant are melt-mixed to obtain masterbatch particles.

[0008] In the present invention, the modified chlorinated polypropylene is maleic anhydride modified chlorinated polypropylene; preferably, the grafting rate of maleic anhydride is 0.5%-3%, preferably 1%-2%, and further preferably 1%-1.5%. As common sense, the grafting rate is measured by existing technology, such as acid-base titration method.

[0009] Preferably, the degree of chlorination of the modified chlorinated polypropylene is 20%-30%; further preferably, the degree of chlorination of the modified chlorinated polypropylene is 22%-26%, which can be 22%, 23%, 24%, 25%, 26% or any value within the range.

[0010] In the present invention, the vulcanizing agent is a peroxide vulcanizing agent, including one or more of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis-25) and trimethylolpropane triacrylate (TMPTA). Preferably, the vulcanizing agent includes 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis-25) and trimethylolpropane triacrylate (TMPTA); further preferably, the weight ratio of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis-25) and trimethylolpropane triacrylate (TMPTA) is 1:(0.5-1.5).

[0011] Generally, zinc oxide is used as an acid absorber in phenolic vulcanization systems, and is rarely used in peroxide vulcanization systems. The present invention introduces a modified CPP material in combination with zinc oxide and operating oil into the PP+EPDM elastomer system to enhance the bonding performance of the PP+EPDM material with metals such as stainless steel, so that the PP+EPDM elastomer material can achieve the function of extruding a sealing strip without adhesive, and at the same time, the performance meets the requirements of products using conventional adhesives. In particular, the prepared PP / EPDM material for a coating-free bonding type sealing strip with a metal skeleton has high temperature resistance, low temperature resistance, and high and low temperature resistance.

[0012] In the present invention, the process oil includes paraffin oil.

[0013] In the present invention, the filler includes talc.

[0014] In the present invention, the colorant includes carbon black.

[0015] In the present invention, the weight ratio of PP resin, EPDM rubber, process oil, modified chlorinated polypropylene, zinc oxide, vulcanizing agent, filler, additive and colorant is (10-30): (25-45): (20-40): (5-20): (1-5): (0.5-2): (10-20): (1-3): (0.5-2).

[0016] Preferably, the weight ratio of PP resin, EPDM rubber, process oil, modified chlorinated polypropylene, zinc oxide, vulcanizer, filler, additive and colorant is (10-20): (25-35): (20-30): (10-20): (1-3): (1-2): (10-20): (1-3): (0.5-2).

[0017] Further preferably, the weight ratio of PP resin, EPDM rubber, process oil, modified chlorinated polypropylene, zinc oxide, vulcanizer, filler, additive and colorant is (10-15): (25-30): (20-25): (15-20): (1.5-2.5): (1.3-2): (12-18): (1-2): (0.5-1).

[0018] In the present invention, the specific method of melt-mixing PP resin, EPDM rubber, operating oil, modified chlorinated polypropylene, zinc oxide, fillers, additives and colorants to obtain masterbatch particles is a conventional technology, and a conventional extruder granulation method can be adopted, or other methods that can melt-mix PP resin, EPDM rubber, operating oil, modified chlorinated polypropylene, zinc oxide, fillers, additives and colorants can be adopted to obtain masterbatch particles.

[0019] In the present invention, the specific method of subjecting the masterbatch to a vulcanizing reaction with a vulcanizing agent to obtain the PP / EPDM material for the metal skeleton free coating bonding type sealing strip is a conventional technology, and a conventional extruder granulation method can be adopted, or other methods that can allow the masterbatch to be subjected to a vulcanizing reaction with a vulcanizing agent to obtain the PP / EPDM material for the metal skeleton free coating bonding type sealing strip can be adopted.

[0020] The present invention discloses a PP / EPDM material for a metal skeleton coating-free bonding sealing strip obtained by vulcanizing the masterbatch particles with a vulcanizing agent. Preferably, when the PP / EPDM material is bonded to the metal, no adhesive is required and good bonding strength can be obtained. Under the standard test method, the bonding strength is ≥6N / m.

[0021] The present invention discloses the use of the PP / EPDM material for the coating-free bonding seal strip with a metal frame in the preparation of a TPV product. Preferably, when the TPV product is bonded to the metal, no adhesive is required and good bonding strength can be obtained. Under the standard test method, the bonding strength is ≥6N / m.

[0022] The present invention discloses the use of the PP / EPDM material for the coating-free bonding seal strip with a metal frame in the preparation of automotive TPV products. Preferably, in the automotive TPV product, when the elastomer is bonded to the metal, no adhesive is required, and good bonding strength can be obtained. Under the standard test method, the bonding strength is ≥6N / m.

[0023] The present invention discloses the use of the PP / EPDM material for the metal frame coating-free bonding seal strip in improving the bonding ability of TPV products. Preferably, when the TPV product is bonded to the metal, no adhesive is required and good bonding strength can be obtained. Under the standard test method, the bonding strength is ≥6N / m.

[0024] The present invention discloses the use of the PP / EPDM material for the coating-free bonding seal strip with a metal frame in the preparation of a TPV product bonded to metal. Preferably, the TPV product bonded to metal does not require an adhesive when bonding to metal, and can achieve good bonding strength, and the bonding strength is ≥6N / m under the standard test method.

[0025] The present invention discloses a TPV product, the raw materials for preparing the product include the PP / EPDM material for the coating-free bonding type sealing strip with a metal frame. Preferably, when the TPV product is used as an elastomer and bonded to a metal, or when the elastomer in the TPV product is bonded to a metal, no adhesive is required, and good bonding strength can be obtained. Under the standard test method, the bonding strength is ≥6N / m.

[0026] The present invention discloses a TPV metal composite product, including a metal and a TPV material bonded to the metal, wherein the raw material for preparing the TPV material includes the above-mentioned PP / EPDM material for the coating-free bonding type sealing strip with the metal skeleton. Preferably, when the TPV material is bonded to the metal, no adhesive is required and good bonding strength can be obtained. Under the standard test method, the bonding strength is ≥6N / m.

[0027] When the prior art combines PP+EPDM dynamic vulcanization material with a metal skeleton, if the PP+EPDM elastomer material is directly co-extruded with stainless steel or aluminum to form a sealing strip, the elastomer material cannot adhere to the stainless steel or aluminum surface and cannot be formed. Therefore, the domestic method of producing sealing strips mainly adopts the method of coating stainless steel or aluminum strip with adhesive, which has a long process, high cost, and VOC volatilization. In the present invention, PP resin, EPDM rubber, operating oil, modified chlorinated polypropylene, zinc oxide, filler, auxiliary agent and colorant are melt-mixed to obtain a masterbatch; the masterbatch is subjected to a vulcanization reaction with a vulcanizing agent to obtain a PP / EPDM material for a metal skeleton free-coating bonding type sealing strip, which has excellent bonding strength with metals such as stainless steel, especially without a primer, the product of the present invention is directly compounded with stainless steel, and the bonding strength is as high as 9N / m, and the prepared PP / EPDM material for a metal skeleton free-coating bonding type sealing strip has high temperature resistance, low temperature resistance and high and low temperature resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a photo of the product of Example 2 of the present invention and metal composite extrusion, showing the bonding strength.

[0029] Figure 2 This is a photo of the product of Example 2 of the present invention and metal composite extrusion, showing the bonding strength.

[0030] Figure 3 This is a photo of an existing TPV product extruded on metal, showing poor bonding. DETAILED DESCRIPTION

[0031] In China, the main method of producing sealing strips is to combine PP+EPDM dynamic vulcanization materials with metal frames by coating adhesives on stainless steel or aluminum strips. The process is long, the cost is high, and VOCs are volatilized. The present invention uses PP resin, EPDM rubber, operating oil, modified chlorinated polypropylene, zinc oxide, vulcanizing agent, filler, additive and colorant as raw materials, and performs two-step granulation to obtain PP / EPDM materials for sealing strips that are free of coating and bonded to metal frames. The materials have excellent bonding strength when bonded to metals such as stainless steel, especially without the need for primer, and the product of the present invention is directly compounded with stainless steel, and the bonding strength is as high as 9N / m. Moreover, the prepared PP / EPDM materials for sealing strips that are free of coating and bonded to metal frames have high temperature resistance, low temperature resistance and high and low temperature resistance.

[0032] In the above technical solution, the modified chlorinated polypropylene is maleic anhydride modified chlorinated polypropylene; preferably, the grafting rate of maleic anhydride is 0.5%-2.5%, preferably 1%-1.5%. As common sense, the grafting rate is measured by existing technology, such as acid-base titration.

[0033] Preferably, the degree of chlorination of the modified chlorinated polypropylene is 20%-30%; further preferably, the degree of chlorination of the modified chlorinated polypropylene is 22%-26%, which can be 22%, 23%, 24%, 25%, 26% or any value within the range.

[0034] In the above technical scheme, the operating oil is paraffin oil; the vulcanizing agent is a peroxide vulcanizing agent; the filler is talcum powder with a particle size of 1500-5000 mesh, preferably 2000-3500 mesh; and the colorant is carbon black masterbatch.

[0035] In the above technical solution, the melt index of the PP resin is 0.2-3 g / 10 min, and the condition is 230° C. / 2.16 kg.

[0036] In the above technical solution, the ENB content of EPDM is 4-6%, the vinyl content is 60-70%, and the Mooney viscosity is 60-80 at 125°C.

[0037] In the above technical solution, the auxiliary agent includes one or more of an antioxidant, an anti-ultraviolet agent, and a lubricant.

[0038] In the present invention, the main ingredient formula of the PP / EPDM material for preparing the coating-free bonding sealing strip with the metal skeleton is as follows according to mass percentage: PP resin balance EPDM rubber 25-45% Operating oil 20-40% Modified chlorinated polypropylene 5-20% Talc 12-18% Zinc oxide 1-3% Preferably, the main ingredient formula of the PP / EPDM material for preparing the coating-free bonding sealing strip with the metal skeleton is as follows, by mass percentage: PP resin balance EPDM rubber 25-30% Operating oil 20-25% Modified chlorinated polypropylene 15-20% Talc 12-18% Zinc oxide 1.5-2.5% In the present invention, by mass percentage, with the main material as 100%, the small material formula is as follows: Vulcanizing agent 0.5-2% Additives 1.5-2% Carbon black masterbatch 0.5-1% Preferably, by mass percentage, with the main ingredient as 100%, the small ingredient formula is as follows: Vulcanizing agent 1.5-2% Additives 1.5-2% Carbon black masterbatch 0.5-1% In the above technical solution, the mass percentage of zinc oxide is 1%-3%; it can be 1%, 1.5%, 2%, 2.5%, 3% or any value within the range.

[0039] After the materials used in the present invention are mixed except for the vulcanizing agent, the remaining materials are directly put into a twin-screw extruder for melting and mixing to form the first masterbatch, and then the masterbatch is pre-mixed with the vulcanizing agent and put into a twin-screw extruder for vulcanization reaction and extrusion to form finished particles; the twin-screw equipment used can have a diameter of 30-75 mm, a rotation speed of 300-1200 rpm, and a temperature of 190-240° C. for processing and forming granulation. The specific preparation method is the existing technology and meets the TPV granulation requirements.

[0040] The following is an explanation of the technical progress of the present invention through specific experiments. The raw materials used are all existing products, and the specific preparation operations and performance tests are all conventional techniques.

[0041] The materials involved in the examples and comparative examples are described as follows.

[0042] PP resin: polypropylene, brand 4220.

[0043] EPDM: Brand 3092PM.

[0044] Operating oil: paraffin-based white oil No. 300.

[0045] Maleic anhydride modified CPP (chlorinated polypropylene) material, maleic anhydride grafting rate 1%, is an existing product or prepared according to an existing method (reference: Synthesis and properties of maleic anhydride grafted chlorinated polypropylene for plastic coatings). In the examples and comparative examples, the existing chlorinated polypropylene (Subi Chemical) is used as the raw material and maleic anhydride is grafted according to the conventional method. The details are as follows: Modifier 1: Maleic anhydride grafted chlorinated polypropylene, chlorinated polypropylene is Subi Chemical SB-9P, chlorine content 24%, grafting rate 1%; Modifier 2: maleic anhydride grafted chlorinated polypropylene, chlorinated polypropylene is Subi Chemical SB-6300, chlorine content 36%, grafting rate 1%; Modifier 3: maleic anhydride grafted chlorinated polypropylene, chlorinated polypropylene is Subi Chemical SB-100P, chlorine content 17%, grafting rate 1%; Comparative modifier: PP grafted maleic anhydride, Mitsui QF551, grafting rate 1%.

[0046] Curing agent: Peroxide 25+TMPTA, mass ratio 1:1.

[0047] Zinc oxide: commercially available powder.

[0048] Talc: 2500 mesh.

[0049] Additives: including antioxidants, anti-UV agents, and lubricants. The antioxidants are 1010 and 168, each accounting for 0.2%, the anti-UV agents are 770 and 234, each accounting for 0.3%, and the lubricants are erucamide and PE wax, each accounting for 0.5%.

[0050] Carbon black colorant: carbon black masterbatch, brand 2718.

[0051] The raw material formula of the embodiment and the comparative example is shown in Table 1, and the processing method is as follows: Except for the vulcanizing agent, the remaining materials are conventionally mixed and directly enter the twin-screw extruder for melt mixing to form the first masterbatch, and then the masterbatch is conventionally mixed with the vulcanizing agent and enters the twin-screw extruder for vulcanization reaction and extrusion to form finished particles; the twin-screw equipment used has a diameter of 55mm, a rotation speed of 700rpm, and a temperature of 190-240℃.

[0052] The testing methods of materials are conventional techniques, and the examples and comparative examples are briefly described as follows: Shore A hardness: According to ISO 868, A scale, 15s reading, requirement is 85+ / -5A.

[0053] Tensile strength: According to ISO 37, test speed 500mm / min, required to be above 7MPa.

[0054] Tensile elongation at break: According to ISO 37, test speed 500mm / min, requirement is 400% or more.

[0055] Bond strength: Stainless steel (without adhesive) is conventionally co-extruded with the elastomeric material of the embodiment or comparative example into a sheet, and the bond strength is tested by a tensile testing machine at a test speed of 50 mm / min. The bond strength is required to be ≥6 N / m.

[0056] High temperature resistance test: According to the requirements of QC-T15-1992 standard for automotive parts, the product is stored at 85℃ for 24 hours without being disconnected.

[0057] High and low temperature cycle: According to the requirements of QC-T15-1992 standard for automotive parts, temperature cycles of -30℃ and 80℃ are carried out, each cycle lasts 24 hours, and 10 cycles are carried out without disconnection.

[0058] Low temperature storage resistance: According to the requirements of QC-T15-1992 standard for automotive parts, store at -30℃ for 24 hours without disconnecting.

[0059] Warm water resistance: According to the automotive parts QC-T15-1992 standard, soak in 40℃ warm water for 240h without falling off.

[0060] The present invention can realize primer-free re-extrusion (TPV wrapped on a stainless steel frame or an aluminum frame for co-extrusion), and the product after re-extrusion meets the production requirements: see Figure 1 , which is a photo of the product of Example 2 of the present invention and the conventional extrusion of the stainless steel frame. In the absence of adhesive, TPV and metal are very well bonded; see Figure 2 , which is a photo of the product of Example 2 of the present invention and the conventional extrusion of the aluminum frame. In the absence of adhesive, TPV and metal are very well bonded; see Figure 3 This is a product photo of TPV (commercially available conventional TPV material) that can be well bonded to metal through adhesive in existing production being extruded with metal without adhesive. Without adhesive, the existing TPV has no bonding with metal.

[0061] Through the experimental comparison in Table 2 and the performance in production, the present invention uses PP resin, EPDM rubber, operating oil, modified chlorinated polypropylene, zinc oxide, vulcanizing agent, filler, additive and colorant as raw materials, and two-step granulation to obtain PP / EPDM material for metal skeleton free coating bonding type sealing strip. The material has excellent bonding strength with metals such as stainless steel and aluminum. In particular, no primer is required, and the product of the present invention is directly extruded with metal composites, and the bonding strength is high. Moreover, the prepared PP / EPDM material for metal skeleton free coating bonding type sealing strip has high temperature resistance, low temperature resistance and high and low temperature resistance. In addition, the process flow of the present invention is simple, efficient and low cost.

[0062] Table 1 Raw material formula of examples and comparative examples, Kg

[0063] Table 2 Performance of Examples and Comparative Examples

Claims

1. A method for preparing a PP / EPDM material for a metal frame free-coating adhesive sealing strip, comprising the following steps: subjecting a masterbatch to a vulcanizing reaction with a vulcanizing agent to obtain a PP / EPDM material for a metal frame free-coating adhesive sealing strip, characterized in that: The masterbatch comprises PP resin, EPDM rubber, process oil, modified chlorinated polypropylene, zinc oxide, filler, auxiliary agent and colorant.

2. The method for preparing the PP / EPDM material for the coating-free bonding sealing strip with the metal frame according to claim 1, characterized in that: The modified chlorinated polypropylene is maleic anhydride modified chlorinated polypropylene.

3. The method for preparing the PP / EPDM material for the coating-free bonding sealing strip with the metal frame according to claim 2, characterized in that: The grafting rate of maleic anhydride is 0.5%-3%; the chlorination degree of modified chlorinated polypropylene is 20%-30%.

4. The method for preparing the PP / EPDM material for the coating-free bonding sealing strip with the metal frame according to claim 1, characterized in that: The vulcanizing agent is a peroxide vulcanizing agent; the operating oil includes paraffin oil; the filler includes talc; and the colorant includes carbon black.

5. The method for preparing the PP / EPDM material for the coating-free bonding sealing strip with the metal frame according to claim 1, characterized in that: The weight ratio of PP resin, EPDM rubber, operating oil, modified chlorinated polypropylene, zinc oxide, vulcanizing agent, filler, additive and colorant is (10-30): (25-45): (20-40): (5-20): (1-5): (0.5-2): (10-20): (1-3): (0.5-2).

6. The PP / EPDM material for metal frame-free coating-free bonding sealing strip obtained by the preparation method of the PP / EPDM material for metal frame-free coating-free bonding sealing strip according to claim 1.

7. Use of the PP / EPDM material for coating-free bonding sealing strips with metal skeletons as claimed in claim 6 in the preparation of TPV products, or in improving the bonding ability of TPV products.

8. Use of the PP / EPDM material for coating-free bonding sealing strips with metal skeletons as claimed in claim 6 in the preparation of automotive TPV products or TPV products bonded to metals.

9. A TPV product, the raw materials for its preparation include the PP / EPDM material for the coating-free bonding sealing strip with a metal frame as claimed in claim 6.

10. A TPV metal composite product, comprising a metal and a TPV material bonded to the metal, wherein: The raw materials for preparing the TPV material include the PP / EPDM material for the coating-free bonding sealing strip with the metal frame as described in claim 6.

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