Solvent-resistant TPV (thermoplastic vulcanizate) material with high melt strength and preparation method thereof

Abstract

The invention discloses a solvent-resistant TPV (thermoplastic vulcanizate) material with high melt strength and a preparation method thereof. The formula of the material comprises 30-60 parts of ethylene propylene diene monomer, 15-40 parts of polypropylene resin, 10-25 parts of rubber oil, 10-25 parts of filler, 0.5-5 parts of lubricant, 0.5-5 parts of cross-linking agent composition, 0.5-10 parts of assistant cross-linking agent and 0.1-3 parts of antioxidant. The preparation method comprises the steps of preparation of an intermediate, preparation of the cross-linking agent composition and cross-linking reaction. The material adopts a phenolic resin vulcanization system, and the product has excellent properties of high melt strength, high temperature and high pressure resistance, chemical solvent resistance and the like, is good in extrusion appearance and rebound resilience, and can be widely applied to cleaning solution conduits of new energy automobiles.

Description

Technical Field

[0001] The invention relates to the field of dynamically vulcanized thermoplastic elastomers, and in particular to a solvent-resistant TPV material with high melt strength and a preparation method thereof. Background Art

[0002] As a common component in automobile manufacturing, the automobile washing liquid duct has a particularly special use environment. It needs to be in contact with chemical solvents for a long time and is required to have excellent explosion-proof performance under high temperature and high pressure conditions. However, traditional TPV materials have exposed many shortcomings in application. The material uses peroxide as a cross-linking agent, which leads to low melt strength, and the processed pipes are prone to rupture under high temperature and high pressure environments. In addition, its large compression permanent deformation and poor rebound performance make the product dimensional stability poor and the service life short. More importantly, traditional TPV materials tend to become brittle at low temperatures, which further limits its scope of application. In contrast, dynamically vulcanized thermoplastic elastomers prepared using phenolic resin as a vulcanizing agent exhibit low pressure set and excellent low-temperature flexibility, making them more suitable for use in cold regions.

[0003] Therefore, how to solve the deficiencies of the above-mentioned prior art and provide a TPV material that is solvent-resistant and has high melt strength has become a subject to be studied and solved by the present invention. Summary of the invention

[0004] The object of the present invention is to provide a TPV material which is resistant to solvents and has high melt strength and a preparation method thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A solvent-resistant TPV material with high melt strength, the raw materials of which include the following components in parts by weight:

[0007] 30-60 parts of EPDM rubber,

[0008] 15-40 parts of polypropylene resin,

[0009] 10-25 parts of rubber oil,

[0010] 10 to 25 parts of filler,

[0011] 0.5-5 parts of lubricant,

[0012] 0.5 to 5 parts of crosslinking agent composition,

[0013] 0.5 to 10 parts of auxiliary crosslinking agent,

[0014] Antioxidant 0.1 to 3 parts.

[0015] According to a further technical solution, the constituent monomers of the EPDM rubber are ethylene and propylene, the third monomer (i.e., the cross-linking monomer) is ethylidene norbornene, the Mooney viscosity ML (1+4) at 125°C is between 50 and 75, the ethylene content is between 50 and 70%, and the cross-linking monomer content is between 5 and 8%.

[0016] In a further technical solution, the polypropylene resin is one or a combination of homopolymer polypropylene or copolymer polypropylene, wherein the copolymer polypropylene is an ethylene-propylene copolymer;

[0017] The polypropylene resin has a melting index of 1.0 to 10.0 g / 10 min (230° C., 2.16 kg) and a melting temperature of 160 to 170° C.

[0018] In a further technical solution, the rubber oil is any one or more of white oil, paraffin oil and naphthenic oil; the kinematic viscosity of the rubber oil at 40°C is 100-300 mm 2 / s, evaporation loss is less than or equal to 0.5%.

[0019] According to a further technical solution, the filler is any one or more combinations of activated calcium carbonate, titanium dioxide, talcum powder, montmorillonite and kaolin.

[0020] According to a further technical solution, the lubricant is a combination of one or more of stearic acid, zinc stearate, calcium stearate, polyethylene wax, paraffin, erucamide, and silicone.

[0021] According to a further technical solution, the crosslinking agent composition is a masterbatch prepared by mixing phenolic resin and polypropylene resin, wherein the mass ratio of the phenolic resin to the polypropylene resin is 1:1 to 1:10.

[0022] According to a further technical solution, the auxiliary cross-linking agent is a mixture of stannous chloride and zinc oxide in a mass ratio of 5:1 to 1:5.

[0023] In a further technical solution, the antioxidant is a combination of one or more of antioxidants 1098, 1010, 3450, 2246, 225, 405, and 445.

[0024] Furthermore, the present invention also discloses a method for preparing a solvent-resistant TPV material having high melt strength, comprising:

[0025] (1) Preparation of intermediate: EPDM rubber, polypropylene resin, rubber oil, filler, lubricant, cross-linking agent and antioxidant are mixed according to weight proportions, put into an internal mixer, and mixed at a temperature of 170 to 190° C. for 20 to 35 min. After being uniformly blended, the mixture is further granulated by single-screw extrusion to obtain an uncross-linked thermoplastic elastomer intermediate;

[0026] (2) Preparation of the crosslinking agent composition: adding phenolic resin and polypropylene resin in a mass ratio of 1:1 to 1:10 into an internal mixer and mixing them uniformly, and then extruding and granulating them through a single screw extruder to obtain the crosslinking agent composition, wherein the internal mixer has a mixing temperature of 100 to 170° C., and the extrusion temperature of the single screw extruder has a mixing temperature of 100 to 170° C.;

[0027] (3) Cross-linking reaction: The thermoplastic elastomer intermediate and the cross-linking agent composition are prepared by weight, placed in a high-speed stirring pot and stirred for 3 to 5 minutes. After being evenly mixed, a dynamic vulcanization process is used for extrusion granulation on a twin-screw extruder. The vulcanization temperature is 170 to 200° C. and the rotation speed is 250 to 350 rpm. The thermoplastic elastomer intermediate undergoes a cross-linking reaction with the cross-linking agent composition and the auxiliary cross-linking agent, thereby obtaining the solvent-resistant TPV material with high melt strength.

[0028] In the above scheme, the percentages specified in this article involving components are all mass percentages.

[0029] The words “include,” “including,” and “have” used in this document are open-ended terms, meaning including but not limited to.

[0030] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0031] The working principle and advantages of the present invention are as follows:

[0032] (1) Compared with the traditional TPV materials cured by peroxide, the present invention adopts phenolic resin as the curing system. Combined with the excellent performance of each component, it can ensure that the material has chemical solvent resistance and low pressure change performance, while giving the material good low-temperature toughness (-40°C), which can further expand its application range to extremely cold areas.

[0033] (2) The present invention adopts a crosslinking agent composition to blend phenolic resin and polypropylene resin into master batches, thereby preventing the phenolic resin from being unevenly fed and from melting and sticking to the inner wall of the extruder feed port due to excessively high temperature, so that the phenolic resin can be evenly dispersed in the matrix material to fully produce a crosslinking reaction.

[0034] (3) The present invention uses a polypropylene resin with a high melting point and a low melting index to improve the melt strength of the material, resist high temperature and high pressure impact, and improve the processing dimensional stability of the material.

[0035] In summary, the present invention mainly replaces the peroxide system with a phenolic resin vulcanization system, and combines the performance of each component to make the material achieve the purpose of chemical solvent resistance, low pressure deformation, and excellent low-temperature flexibility. By selecting a polypropylene resin with a high melting point and a low melt index, the melt strength of the material can be increased and the processing performance can be improved. Therefore, it has outstanding substantial effects and significant progress. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with embodiments:

[0037] Embodiment: The present invention will be described in detail below. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0038] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0039] A method for preparing a solvent-resistant TPV material having high melt strength according to an embodiment of the present invention specifically comprises the following steps:

[0040] (1) Preparation of intermediate: EPDM rubber, polypropylene resin, rubber oil, filler, lubricant, cross-linking agent and antioxidant are mixed according to weight proportions, put into an internal mixer, and mixed at a temperature of 170 to 190° C. for 20 to 35 min. After being uniformly blended, the mixture is further granulated by single-screw extrusion to obtain an uncross-linked thermoplastic elastomer intermediate;

[0041] (2) Preparation of the crosslinking agent composition: adding phenolic resin and polypropylene resin in a mass ratio of 1:1 to 1:10 into an internal mixer and mixing them uniformly, and then extruding and granulating them through a single screw extruder to obtain the crosslinking agent composition, wherein the internal mixer has a mixing temperature of 100 to 170° C., and the extrusion temperature of the single screw extruder has a mixing temperature of 100 to 170° C.;

[0042] (3) Cross-linking reaction: The thermoplastic elastomer intermediate and the cross-linking agent composition are prepared by weight according to Table 1, placed in a high-speed stirring pot and stirred for 3 to 5 minutes. After being uniformly mixed, a dynamic vulcanization process is used for extrusion granulation on a twin-screw extruder. The vulcanization temperature is 170 to 200° C. and the rotation speed is 250 to 350 rpm. The thermoplastic elastomer intermediate undergoes a cross-linking reaction with the cross-linking agent composition and the auxiliary cross-linking agent, thereby obtaining the solvent-resistant TPV material having high melt strength.

[0043] Comparative Examples 1 to 3: According to the weight ratio in Table 1, Comparative Examples 1 to 2 use peroxide instead of phenolic resin as a crosslinking agent, and the other components and steps are the same as those of Examples 1 to 2. Comparative Example 3 uses a high melt index polypropylene resin, and the other components and steps are the same as those of Example 3.

[0044] Table 1 Raw material composition formula of embodiment and comparative example (unit: weight parts)

[0045]

[0046] The fillers in Examples 1 to 6 and Comparative Examples 1 to 3 are all activated calcium carbonate.

[0047] The antioxidants in Examples 1 to 6 and Comparative Examples 1 to 3 are all compositions of antioxidant 1010 and antioxidant 225 mixed in a mass ratio of 1:1.

[0048] The lubricants of Examples 1 to 6 and Comparative Examples 1 to 3 are all compositions of stearic acid and polyethylene wax mixed in a mass ratio of 1:1.

[0049] The base materials of Examples 1 to 6 and Comparative Examples 1 to 3 are all prepared according to the weight proportions in Table 1, and are uncrosslinked thermoplastic elastomer intermediates prepared by the first step of mixing and extrusion.

[0050] The crosslinking agent compositions of Examples 1 to 6 and Comparative Example 3 are all compositions in which phenolic resin and polypropylene resin are mixed in a mass ratio of 1:3.

[0051] Table 2 Performance test results of the embodiments and comparative examples

[0052]

[0053] From the performance test results of Comparative Examples 1 and 2, it can be observed that, compared with the peroxide vulcanization system, the use of the phenolic resin vulcanization system can significantly improve the resilience of the TPV material and improve the compression permanent deformation performance of the material. From the performance test results of Comparative Example 3, it can be observed that after using a higher melt index polypropylene resin, the melt index of the TPV material is significantly increased, the chemical solvent resistance and low temperature toughness are poor, and it is easy to produce problems such as melt deformation and cracking during the actual extrusion process.

[0054] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A solvent-resistant TPV material with high melt strength, characterized in that: The raw materials include the following components by weight: 30~60 parts of EPDM rubber, Polypropylene resin 15~40 parts, 10~25 parts of rubber oil, 10~25 parts of filler, 0.5~5 parts of lubricant, 0.5 to 5 parts of a crosslinking agent composition, 0.5~10 parts of auxiliary cross-linking agent, Antioxidant 0.1~3 parts.

2. The solvent-resistant TPV material with high melt strength according to claim 1, characterized in that: The constituent monomers of the EPDM rubber are ethylene and propylene, the third monomer is ethylidene norbornene, the Mooney viscosity ML (1+4) at 125° C. is between 50 and 75, the ethylene content is between 50 and 70%, and the cross-linking monomer content is between 5 and 8%.

3. The solvent-resistant TPV material with high melt strength according to claim 1, characterized in that: The polypropylene resin is one or a combination of homopolymer polypropylene or copolymer polypropylene, wherein the copolymer polypropylene is an ethylene-propylene copolymer; The polypropylene resin has a melting index of 1.0-10.0 g / 10 min (230° C., 2.16 kg) and a melting temperature of 160-170° C.

4. The solvent-resistant TPV material with high melt strength according to claim 1, characterized in that: The rubber oil is any one or more combinations of white oil, paraffin oil and naphthenic oil; The kinematic viscosity of the rubber oil at 40°C is 100-300 mm 2 / s, evaporation loss is less than or equal to 0.5%.

5. The solvent-resistant TPV material with high melt strength according to claim 1, characterized in that: The filler is any one or more combinations of activated calcium carbonate, titanium dioxide, talcum powder, montmorillonite and kaolin.

6. The solvent-resistant TPV material with high melt strength according to claim 1, characterized in that: The lubricant is a combination of one or more of stearic acid, zinc stearate, calcium stearate, polyethylene wax, paraffin, erucamide, and silicone.

7. The solvent-resistant TPV material with high melt strength according to claim 1, characterized in that: The crosslinking agent composition is a master batch prepared by mixing phenolic resin and polypropylene resin, wherein the mass ratio of the phenolic resin to the polypropylene resin is 1:1-1:

10.

8. The solvent-resistant TPV material with high melt strength according to claim 1, characterized in that: The auxiliary cross-linking agent is prepared by mixing stannous chloride and zinc oxide in a mass ratio of 5:1 to 1:

5.

9. The solvent-resistant TPV material with high melt strength according to claim 1, characterized in that: The antioxidant is a combination of one or more of antioxidants 1098, 1010, 3450, 2246, 225, 405, and 445.

10. A method for preparing a solvent-resistant TPV material having high melt strength, characterized in that: A method for preparing a solvent-resistant TPV material having high melt strength as claimed in any one of claims 1 to 9, comprising: (1) Preparation of intermediate: EPDM rubber, polypropylene resin, rubber oil, filler, lubricant, cross-linking agent and antioxidant are mixed according to weight proportions and put into an internal mixer at a mixing temperature of 170-190°C for 20-35 minutes. After being uniformly blended, the mixture is further extruded and granulated by a single screw extruder to obtain an uncross-linked thermoplastic elastomer intermediate. (2) Preparation of a crosslinking agent composition: adding a phenolic resin and a polypropylene resin in a mass ratio of 1:1 to 1:10 into an internal mixer and mixing them uniformly, and then extruding and granulating them through a single screw extruder to obtain the crosslinking agent composition, wherein the internal mixer has a mixing temperature of 100 to 170° C., and the extrusion temperature of the single screw extruder has a mixing temperature of 100 to 170° C.; (3) Cross-linking reaction: The thermoplastic elastomer intermediate and the cross-linking agent composition are prepared by weight, placed in a high-speed stirring pot and stirred for 3 to 5 minutes. After being evenly mixed, a dynamic vulcanization process is used for extrusion granulation on a twin-screw extruder. The vulcanization temperature is 170 to 200° C. and the rotation speed is 250 to 350 rpm. The thermoplastic elastomer intermediate undergoes a cross-linking reaction with the cross-linking agent composition and the auxiliary cross-linking agent, thereby obtaining the solvent-resistant TPV material having high melt strength.

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