Crosslinking system for fluoroelastomers

Abstract

The present invention provides a uniquely designed crosslinking system for fluoroelastomers which is a bisphenol-free safe crosslinking system for fluoroelastomers comprising the following components: a) a phase transfer catalyst selected from a quaternary ammonium salt or a quaternary phosphonium salt; b) a non-bisphenol curative; c) a dispersing agent; d) a processing aid; and e) at least one additive. The uniquely designed crosslinking system would be useful in the preparation of commercially available fluoroelastomer / fluoropolymer which exhibits high heat resistance, chemical resistance, aging resistance and weather resistance, excellent inertness to solvents, hydrocarbons, acids and bases, low dielectric constant, low flammability, low refractive index, low surface energy and low moisture absorption.

Description

Technical Field

[0001] This disclosure relates to novel and safer crosslinking systems for fluorinated elastomers.

[0002] definition

[0003] As used in this disclosure, the following terms are generally intended to have the meanings set forth below, unless the context in which they are used indicates otherwise.

[0004] FKM is a family of fluorocarbon-based fluoroelastomer materials defined by the ASTM international standard. FKM is the abbreviation for American Standard (ASTM) for fluoroelastomers or fluororubber materials. F stands for fluorine; K is an abbreviation of the German word Kohlenstoff, meaning carbon; and M is the name of saturated main-chain rubber from ASTM.

[0005] FFKM is a perfluorinated elastomer blend with a higher fluorine content than FKM fluorinated elastomer.

[0006] Phr or phr (parts per hundred parts of rubber) is a unit of measurement used by rubber chemists to describe how much of a certain component is needed. Background Technology

[0007] The following background information is relevant to this disclosure, but is not necessarily prior art.

[0008] Fluorinated elastomers are an important class of high-performance elastomers due to their unique combination of versatility and related properties. They have wide applications in strategic materials, automotive, aerospace, electronics, and energy industries. Fluorinated elastomers exhibit excellent thermal stability, oil resistance, superior mechanical properties, and wear resistance. These properties are primarily related to the low polarizability and strong electronegativity of fluorine atoms, along with their small van der Waals radius (1.32 Å) and strong CF bonds (485 kJ / mol). -1 )related.

[0009] Therefore, fluorinated elastomers exhibit high heat resistance, chemical resistance, aging resistance and weather resistance, excellent inertness to solvents, hydrocarbons, acids and alkalis, low dielectric constant, low flammability, low refractive index, low surface energy and low hygroscopicity.

[0010] Commercially available fluorinated elastomers are mainly of two types: FKM elastomers and FFKM elastomers. FKM elastomers are highly fluorinated (perfluorinated) polymers in which vinylidene fluoride (VDF) is used as a partially fluorinated comonomer. FFKM perfluorinated elastomers are fully fluorinated hydrocarbons in which CH bonds are absent, but they do have ether linkages. FFKMs are resistant to exposure to virtually any chemical.

[0011] The curing reaction in FKM elastomers is related to the strong polarity of the CF bond, which leads to molecular polarization, thereby eliminating hydrofluoric acid (HF) under the influence of several factors such as the incorporation of additives. Existing crosslinking systems are based on diamine derivatives, bisphenol derivatives, peroxides and auxiliaries, as well as high-energy radiation. Among these, the bisphenol curing system is the most widely used system for crosslinking fluorinated elastomers. However, the bisphenol curing system has several problems, such as causing endocrine disorders, reproductive problems, and other health hazards.

[0012] Fluorinated elastomers and perfluoroelastomers (elastomer perfluoropolymers) exhibit excellent high-temperature resistance and chemical resistance in both cured and uncured states. These properties are attributed to the stability and inertness of the copolymerized fluorine and perfluorinated monomer units, which form the main part of the polymer backbone. Tetrafluoroethylene (TFE), perfluoro(methyl vinyl) ethers, perfluoro(propyl vinyl) ethers, etc., are disclosed in U.S. Patent Nos. 3,467,638; 3,682,872; 4,035,565; 4,281,092; and 4,972,038.

[0013] However, fluoroelastomers and perfluoroelastomers also necessarily contain small amounts of monomers with less stable copolymerization curing sites. Furthermore, many perfluoroelastomers contain reactive end groups introduced during polymerization using chain transfer agents or molecular weight regulators. Such structural portions must possess high reactivity to facilitate efficient crosslinking and curing chemistry, but this reactivity inherently makes the polymer more susceptible to degradation-related chemical reactions (such as oxidation). Consequently, certain physical properties of the polymer (particularly compression set and high-temperature stress / strain properties) are adversely affected.

[0014] Warner, John, et al. disclosed in WO 2018 / 005430 A1 a bisphenol A-free crosslinking system based on amphiphiles and polynucleophiles and its application in tank linings, etc. They disclosed the potential health hazards due to the crosslinking of bisphenols in the polymer. The disclosed curing agents are dianhydrides, bisphenols (other than BPA), polyepoxides, diesters, and polyphenols, as well as styrene and unsaturated polyesters. However, these disclosures do not involve any fluoropolymers or fluoroelastomers.

[0015] Hintzer et al. described a cured fluorinated elastomer composition in U.S. Patent 9,982,091B2, which comprises reaction products of a curing reaction of a composition using a peroxide curing system. This peroxide curing system is a commonly used curing system based on a peroxide curing reaction using suitable curing compounds that have or generate peroxides, which are believed to subsequently generate free radicals. Fluorinated elastomers suitable for use in peroxide curing systems (peroxide-curable fluorinated elastomers) contain reactive sites, including halogens such as bromine and / or iodine. It is generally believed that bromine or iodine atoms are abstracted in free radical peroxide curing reactions, thereby causing crosslinking of the fluorinated polymer molecules and the formation of a three-dimensional network. The highly fluorinated elastomers of this invention may also contain other curing sites that may be reactive to the peroxide curing system or to other curing systems, such as, but not limited to, bisphenol curing systems or triazine curing systems. This invention discloses various peroxide initiators, including hydrogen peroxide, diacyl peroxide, diacetyl peroxide, dipropionyl peroxide, dibutyryl peroxide, dibenzoyl peroxide, benzoylacetyl peroxide, diglutaric acid peroxide, dilauryl peroxide, and water-soluble peracids and salts (such as ammonium, sodium, or potassium salts). Suitable redox systems are also disclosed, including combinations of peroxydisulfate and bisulfite or disulfite, combinations of thiosulfate and peroxydisulfate, or combinations of peroxydisulfate and hydrazine.

[0016] Suzuki et al. disclosed a method for preparing partially fluorinated elastomers using a crosslinking system in US10,329,404 B2. The curing system used is a peroxide, such as benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, tert-butylperoxybenzoate, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane-3, lauroyl peroxide, or bisphenol or amine curables. The method also discloses the use of various inorganic fillers such as carbon black, graphite, clay, silica, talc, diatomaceous earth, barium sulfate, wollastonite, calcium carbonate, calcium fluoride, titanium dioxide, and iron oxide.

[0017] Jochum et al. disclosed peroxide-curable fluoropolymers in US10875948. These fluoropolymers possess suitable curing sites, which are reactive groups capable of crosslinking in the presence of a suitable crosslinking agent. The curing system is based on a peroxide curing reaction, using appropriate curing compounds that have or generate peroxides, which are thought to generate free radicals.

[0018] However, those skilled in the art are aware that peroxides as curing agents (crosslinking agents) have disadvantages, namely, peroxide curing agents may have some disadvantages, including: low scorch safety, poor heat-oxidative aging resistance, weak stability at high temperatures, poor tensile strength and tear strength, low elasticity and dynamic properties, and a tendency to decompose into odorous byproducts, such as volatile organic compounds (VOCs).

[0019] Furthermore, the use of crosslinking agents such as bisphenol A, AF, or peroxide-type crosslinkers has inherent drawbacks, namely, exposure to them is unsafe for health, and their high potency poses a health risk. (LD50 has been reported to be present in some cases.) 50 LC 50 The value is significantly low.

[0020] Furthermore, it has been observed that fluorinated elastomers obtained from the disclosed crosslinking systems and methods often exhibit drawbacks in most important curing parameters, such as variations or undesirable optimal curing times (TC). 90 Burning time TS1 or TS2, minimum torque (M H Maximum torque (M) L ) and the difference ΔM between the maximum torque and the minimum torque.

[0021] Therefore, there is a need to explore unique and safe crosslinking systems for fluorinated elastomers that are free of bisphenol A, which mitigate the drawbacks mentioned to date and at least provide alternative solutions.

[0022] Purpose

[0023] Some of the objectives of this disclosure are as follows, and at least one embodiment thereof satisfies these objectives:

[0024] One object of this disclosure is to improve one or more problems of the prior art, or at least to provide a useful alternative.

[0025] Another objective of this disclosure is to provide a safe and novel crosslinking system for fluorinated elastomers.

[0026] Another objective of this disclosure is to provide a non-toxic crosslinking system.

[0027] Another object of this disclosure is to provide a crosslinking system that produces a fluorinated elastomer with improved curing properties, rheological properties, physical-mechanical properties, crosslinking density, and compression set resistance.

[0028] Another object of this disclosure is to provide a method for preparing crosslinking systems for fluorinated elastomers.

[0029] Another object of this disclosure is to provide a method for crosslinking fluorinated elastomers using a crosslinking system.

[0030] Other objects and advantages of this disclosure will become more apparent from the following description, which is not intended to limit the scope of this disclosure. Summary of the Invention

[0031] In one aspect of the invention, it relates to a bisphenol-free, safe crosslinking system for fluorinated elastomers, the crosslinking system comprising the following components:

[0032] a) A phase transfer catalyst selected from quaternary ammonium salts or quaternary phosphonium salts;

[0033] b) Non-bisphenol curing agent;

[0034] c) Dispersant;

[0035] d) Processing aids; and

[0036] e) At least one additive.

[0037] In another aspect of the invention, a method for preparing a crosslinking system for fluorinated elastomers is disclosed, the method comprising sequentially and progressively mixing a curing agent, a phase transfer catalyst, a dispersant, a processing aid, and additives to prepare a pre-compound for crosslinking fluorinated elastomers / fluoropolymers. In the method for preparing fluorinated elastomers using the novel crosslinking system, the crosslinking system is added to the premixed fluorinated elastomer at a temperature of 35-70°C for 10-60 minutes, followed by a curing process of 10-50 hours.

[0038] In another aspect of the invention, it relates to a method for preparing a crosslinking system for fluorinated elastomers, the method comprising a method for preparing the crosslinking system, wherein the optimized amount is contained within the following range:

[0039] a. Phase transfer catalysts ranging from 0.1 phr to 2.0 phr;

[0040] b. Non-bisphenol curing agents ranging from 0.1 phr to 4.0 phr;

[0041] c.0.2 phr to 3.0 phr of dispersant;

[0042] Processing aids ranging from 0.5 phr to 5.0 phr; and

[0043] e. At least one additive from 2.0 phr to 10 phr.

[0044] Further aspects of the invention are described in detail in the following description and embodiments sections, wherein many modifications may be made to embodiments of the invention without departing from the scope of this disclosure. Detailed Implementation

[0045] This disclosure relates to a novel and safe bisphenol-free crosslinking system for use in fluorinated elastomers.

[0046] Implementation schemes are provided to thoroughly and fully communicate the scope of this disclosure to those skilled in the art. Numerous details, relating to specific components and methods, are set forth to provide a complete understanding of the implementation schemes of this disclosure. It will be apparent to those skilled in the art that the details provided in the implementation schemes should not be considered as limiting the scope of this disclosure. In some implementation schemes, well-known processes, well-known equipment structures, and well-known techniques are not described in detail.

[0047] The terminology used in this disclosure is for the purpose of explaining particular embodiments only, and such terminology should not be considered as limiting the scope of this disclosure. As used in this disclosure, the forms “a” and “the” may also be intended to include plural forms unless the context clearly indicates otherwise. The terms “comprising,” “including,” and “having” are open-ended transitional phrases and therefore specify the presence of the stated features, integers, steps, operations, elements, modules, units, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The specific order of steps disclosed in the methods and processes of this disclosure should not be construed as necessarily requiring them to be performed in the manner described or illustrated. It should also be understood that additional or alternative steps may be employed.

[0048] As used herein, the term “and / or” includes any and all combinations of one or more of the related listed elements.

[0049] The terms first, second, third, etc., should not be construed as limiting the scope of this disclosure, as these terms may only be used to distinguish one element, component, region, layer, or segment from another. Terms such as first, second, third, etc., as used herein do not imply a particular order or sequence unless clearly indicated by this disclosure.

[0050] In one embodiment of the invention, a bisphenol-free, safe crosslinking system for fluorinated elastomers is provided, the crosslinking system comprising the following components:

[0051] a) A phase transfer catalyst selected from quaternary ammonium salts or quaternary phosphonium salts;

[0052] b) Non-bisphenol curing agent;

[0053] c) Dispersant;

[0054] d) Processing aids; and

[0055] e) At least one additive.

[0056] In another embodiment of the invention, during the crosslinking process of the fluorinated elastomer, the above five components of the crosslinking system can be formulated into a single composition, or into two or more components followed by other components of the composition.

[0057] The bisphenol-free safe crosslinking system for fluorinated elastomers according to the present invention, wherein in step a) of this embodiment, a phase transfer catalyst is provided for the purpose of enhancing the reaction rate and improving the crosslinking efficiency.

[0058] In the specific implementation scheme, the inventors used a phase transfer catalyst, which can be selected from, but is not limited to, quaternary ammonium salts or quaternary phosphorus salts.

[0059] In the specific implementation scheme, the inventors used the following phase transfer catalysts: quaternary ammonium salts selected from cetyltrimethylammonium chloride, cetyltriethylammonium chloride, hexadecyltrimethylammonium chloride, lauryltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium iodide, cetyltrimethylammonium bromide, and cetyltrimethylammonium iodide; or quaternary phosphonium salts selected from benzyltriphenylphosphonium chloride, triphenylphosphonium chloride, trimethyl(4-vinylbenzyl)phosphonium chloride, and (methoxymethyl)triphenylphosphonium chloride.

[0060] In step b) of this embodiment, a non-bisphenol curing agent is provided, wherein the non-bisphenol curing agent replaces the bisphenol compound in conventional known curing agents to ensure effective crosslinking without compromising safety.

[0061] In step b) of this embodiment, a non-bisphenol curing agent is provided, which may be selected from, but is not limited to, phloroglucinol (1,3,5-trihydroxybenzene), resorcinol (1,3-dihydroxybenzene), phloroglucinol glucoside, flavylium salt of phloroglucinol, fenotrol, resorcinol monobenzoate, resorcinol monoacetate, ellagic acid, or mixtures thereof.

[0062] In a specific embodiment, the inventors used phloroglucinol (1,3,5-trihydroxybenzene) having the formula C6H3(OH)3; however, in another specific instance, resorcinol (1,3-dihydroxybenzene) (having the formula C6H4(OH)2) was used for curing.

[0063] The inventors observed that phloroglucinol (1,3,5-trihydroxybenzene) exhibited an IC50 of approximately 863.6 ± 0.06 µM. 50 The value, which is consistent with the reported IC 50 Compared to bisphenol AF with a value of approximately 73.04 ± 0.07 µM, it is clearly 11 times safer and better, thus making the crosslinking system safe and bisphenol-free with comparable or improved desired elastomer properties.

[0064] The inventors of this invention observed an overall difference in order to provide a safer alternative to bisphenol, which resulted in the crosslinking system of this invention for fluorinated elastomers being non-toxic, economical, and providing excellent or similar physical-mechanical properties and compression set resistance (C-set).

[0065] In step c) of this embodiment, a dispersant is provided that maintains a uniform distribution of the components within the fluorinated elastomer matrix during processing.

[0066] In a specific implementation, the inventors used a dispersant, which may be selected from, but is not limited to, diacetone alcohol, polyethylene glycol 400 (PEG 400), dimethyl sulfoxide (DMSO), dimethylformamide, methanesulfonylmethane, fluorosiloxane, and cyclohexanol.

[0067] In step d) of this embodiment, a processing aid is provided that facilitates processing, thereby ensuring consistent material properties of the elastomer.

[0068] In the specific implementation scheme, the inventors used a processing aid, which can be selected from the group including carnauba wax (from Nanjing Tianshi New Material Technology Co., Ltd., No. 29 Caofang Road, Liuhe Economic Development Zone, Nanjing, China), beeswax and candelilla wax (from Longchang Biochemical Co., Ltd., Weifang City, Changyi City, Shibu Economic Development Zone, Shandong Province, China).

[0069] In step e) of this embodiment, at least one additive is provided that provides additional performance benefits, such as improved thermal stability or chemical resistance.

[0070] In the specific implementation, the inventors used an additive selected from, but not limited to, magnesium oxide (MgO), calcium oxide (CaO), barium oxide (BaO), magnesium hydroxide Mg(OH)2, calcium hydroxide Ca(OH)2, and barium hydroxide Ba(OH)2.

[0071] In another embodiment of the invention, a method for preparing a crosslinking system for fluorinated elastomers is provided, the method comprising sequentially mixing a curing agent, a phase transfer catalyst, a dispersant, a processing aid, and additives to prepare a premix suitable for crosslinking fluorinated elastomers / fluoropolymers.

[0072] In another embodiment of the invention, a method for preparing a crosslinking system for fluorinated elastomers is provided, wherein the amounts are contained in the following ranges:

[0073] a. Phase transfer catalysts ranging from 0.1 phr to 2.0 phr;

[0074] b. Non-bisphenol curing agents ranging from 0.1 phr to 4.0 phr;

[0075] c.0.2 phr to 3.0 phr of dispersant;

[0076] Processing aids ranging from 0.5 phr to 5.0 phr; and

[0077] e. At least one additive from 2.0 phr to 10.0 phr.

[0078] In another embodiment of the invention, a method for preparing a crosslinked fluorinated elastomer is provided, the method comprising:

[0079] a. Mixing the components of the crosslinking system according to claim 1 with a fluorinated elastomer to obtain a first mixture, wherein the first mixture comprises a phase transfer catalyst; a non-bisphenol curing agent; and a dispersant;

[0080] b. Add processing aids and additives to the first mixture to obtain a second mixture; and

[0081] c. Mature the second mixture to obtain a cross-linked fluorinated elastomer.

[0082] In yet another embodiment of the invention, a method is provided in which a crosslinking system is added to a premixed fluorinated elastomer at a temperature of 35-70°C for 10-60 minutes.

[0083] In yet another embodiment of the invention, a method is provided in which the cross-linked fluorinated elastomer product obtained after mixing is subjected to a curing time of 10-50 hours.

[0084] In another embodiment of the present invention, the crosslinked fluorinated elastomer produced by using the crosslinking system disclosed herein can be used in aerospace applications, automotive applications, seals, O-ring applications, etc.

[0085] In the implementation plan, the cross-linking system does not cause acute health hazards and is non-toxic.

[0086] In the implementation plan, cross-linked fluorinated elastomers exhibit significant curing properties compared to existing cross-linking systems.

[0087] In the implementation plan, cross-linked fluorinated elastomers exhibit significant and superior physical-mechanical properties compared to existing cross-linking systems.

[0088] In the implementation plan, the cross-linked fluorinated elastomer exhibits significantly higher compression set (C-set) compared to existing cross-linking systems.

[0089] The invention is described in more detail in the following examples, which are intended to be illustrative only, as many modifications and variations within the scope of the invention will be apparent to those skilled in the art. Unless otherwise stated, all portions, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are obtained from or available from chemical suppliers.

[0090] The following examples illustrate the nature of the invention and are provided for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0091] Reference Example: Using bisphenol AF as a curing agent and benzyltriphenylphosphonium chloride (BTPPC) as a phase transfer catalyst

[0092] In step-1, the curing agent bisphenol AF (2.0 phr) was added to the experimental batch and mixed with the phase transfer catalyst benzyltriphenylphosphonium chloride (BTPPC) (0.5 phr) for 5-10 minutes to prepare the premix.

[0093] Add the premixed material from step-1 to the FKM elastomer (100 phr).

[0094] Step-2 involves adding the additives magnesium oxide (3.0 phr), calcium hydroxide (6.0 phr), and MT carbon black (30 phr) to the premixed FKM elastomer at 50°C for 10-15 minutes.

[0095] Step 3 includes a mixing process performed using a Brabender Plasticorder PLE 330 (viscosity tester) operated at a rotor speed of 20-60 rpm to produce the final mix.

[0096] Step-4 allows it to mature for 12-24 hours.

[0097] Step 5: Use a rubber processing analyzer (D-RPA 3000) to evaluate the curing properties of the mixture.

[0098] The results of the analysis and evaluation are summarized as follows:

[0099]

[0100] Example: 01

[0101] In step-1, the curing agent phloroglucinol (0.5 phr) is added to the experimental batch and mixed with the phase transfer catalyst benzyltriphenylphosphonium chloride (BTPPC) (0.7 phr) and the dispersant fluorosiloxane (0.5 phr) for 5-10 minutes to prepare a premix.

[0102] Add the premixed material from step-1 to the FKM elastomer (100 phr).

[0103] Step-2 involves adding the additives magnesium oxide (3.0 phr), calcium hydroxide (6.0 phr), MT carbon black, and carnauba wax as processing aids to the premixed FKM elastomer at 50°C for 10-15 minutes.

[0104] Step 3 includes a mixing process that takes place in a Brabender Plasticorder PLE 330 at a rotor speed of 20-60 rpm to produce the final mix.

[0105] Step-4 allows it to mature for 12-24 hours.

[0106] Step 5: Use a rubber processing analyzer (D-RPA 3000) to evaluate the curing properties of the mixture.

[0107] The results of the analysis and evaluation are summarized as follows:

[0108]

[0109] Example: 02

[0110] In step-1, resorcinol (0.65 phr) is added to the experimental batch as a curing agent and mixed with benzyltriphenylphosphonium chloride (BTPPC) (0.7 phr) as a phase transfer catalyst and diacetone alcohol (0.5 phr) as a dispersant for 5-10 minutes to prepare a premix.

[0111] Add the premixed material from step-1 to the FKM elastomer (100 phr).

[0112] Step-2 involves adding the additives magnesium oxide (3.0 phr), calcium hydroxide (6.0 phr), MT carbon black, and carnauba wax as processing aids to the premixed FKM elastomer at 50°C for 10-15 minutes.

[0113] Step 3 includes a mixing process that takes place in a Brabender Plasticorder PLE 330, operated at a rotor speed of 60 rpm, to produce the final mix.

[0114] Step-4 allows it to mature for 12-24 hours.

[0115] Step 5: Use a rubber processing analyzer (D-RPA 3000) to evaluate the curing properties of the mixture.

[0116] The results of the analysis and evaluation are summarized as follows:

[0117]

[0118] Example 3: 03

[0119] In step-1, the curing agent phloroglucinol (0.5 phr) is added to the experimental batch and mixed with the phase transfer catalyst cetyltrimethylammonium bromide (0.7 phr) and the dispersant dimethyl sulfoxide (DMSO) (0.5 phr) for 5-10 minutes to prepare a premix.

[0120] Add the premixed material from step-1 to the FKM elastomer (100 phr).

[0121] Step-2 involves adding the additives magnesium oxide (3.0 phr), calcium hydroxide (6.0 phr), MT carbon black, and carnauba wax as processing aids to the premixed FKM elastomer at 50°C for 10-15 minutes.

[0122] Step 3 includes a mixing process that takes place in a Brabender Plasticorder PLE 330, operated at a rotor speed of 60 rpm, to produce the final mix.

[0123] Step-4 allows it to mature for 12-24 hours.

[0124] Step 5: Use a rubber processing analyzer (D-RPA 3000) to evaluate the curing properties of the mixture.

[0125] The results of the analysis and evaluation are summarized as follows:

[0126]

[0127] Example 4

[0128] In step-1, the curing agent phloroglucinol (0.5 phr) is added to the experimental batch and mixed with the phase transfer catalyst benzyltriphenylphosphonium chloride (BTPPC) (0.7 phr) and the dispersant dimethyl sulfoxide (DMSO) (0.5 phr) for 5-10 minutes to prepare the premix.

[0129] Add the premixed material from step-1 to the FKM elastomer (100 phr).

[0130] Step-2 involves adding the additives magnesium oxide (3.0 phr), calcium hydroxide (6.0 phr), MT carbon black, and carnauba wax as processing aids to the premixed FKM elastomer at 50°C for 10-15 minutes.

[0131] Step 3 includes a mixing process that takes place in a Brabender Plasticorder PLE 330 at a rotor speed of 20-60 rpm to produce the final mix.

[0132] Step-4 allows it to mature for 12-24 hours.

[0133] Step 5: Use a rubber processing analyzer (D-RPA 3000) to evaluate the curing properties of the mixture.

[0134] The results of the analysis and evaluation are summarized as follows:

[0135]

[0136] Example 5: 05

[0137] In step-1, the curing agent phloroglucinol (0.5 phr) is added to the experimental batch and mixed with the phase transfer catalyst benzyltriphenylphosphonium chloride (BTPPC) (0.7 phr) and the dispersant dimethylformamide (0.5 phr) for 5-10 minutes to prepare a premix.

[0138] Add the premixed material from step-1 to the FKM elastomer (100 phr).

[0139] Step-2 involves adding the additives magnesium oxide (3.0 phr), calcium hydroxide (6.0 phr), MT carbon black, and carnauba wax as processing aids to the premixed FKM elastomer at 50°C for 10-15 minutes.

[0140] Step 3 includes a mixing process that takes place in a Brabender Plasticorder PLE 330, operated at a rotor speed of 60 rpm, to produce the final mix.

[0141] Step-4 allows it to mature for 12-24 hours.

[0142] Step 5: Use a rubber processing analyzer (D-RPA 3000) to evaluate the curing properties of the mixture.

[0143] The results of the analysis and evaluation are summarized as follows:

[0144]

[0145] Example 6

[0146] In step-1, the curing agent phloroglucinol (0.5 phr) is added to the experimental batch and mixed with the phase transfer catalyst benzyl ammonium chloride (0.7 phr) and the dispersant dimethyl sulfoxide (DMSO) (0.5 phr) for 5-10 minutes to prepare a premix.

[0147] Add the premixed material from step-1 to the FKM elastomer (100 phr).

[0148] Step-2 involves adding the additives magnesium oxide (3.0 phr), calcium hydroxide (6.0 phr), MT carbon black, and carnauba wax as processing aids to the premixed FKM elastomer at 50°C for 10-15 minutes.

[0149] Step 3 includes a mixing process that takes place in a Brabender Plasticorder PLE 330 at a rotor speed of 20-60 rpm to produce the final mix.

[0150] Step-4 allows it to mature for 12-24 hours.

[0151] Step 5: Use a rubber processing analyzer (D-RPA 3000) to evaluate the curing properties of the mixture.

[0152] The results of the analysis and evaluation are summarized as follows:

[0153]

[0154] Compared to the reference embodiment showing the use of bisphenol AF (which is generally considered unsafe for coatings of polymers used as food-grade polymers), the unique bisphenol-free, safe crosslinking system for fluorinated elastomers developed according to the present invention can be used for commercial-scale purposes for the development of safe crosslinking of fluorinated polymers / fluorinated elastomers. This crosslinking system comprises the following components: a phase transfer catalyst selected from quaternary ammonium salts or quaternary phosphonium salts; a non-bisphenol curing agent; a dispersant; a processing aid; and additives.

[0155] Technological advancements:

[0156] The present disclosure described above has several technical advantages, including but not limited to realizing crosslinking systems for fluorinated elastomers, wherein:

[0157] It will not cause acute health hazards;

[0158] • Provide cross-linked fluorinated elastomers with significant physical-mechanical properties;

[0159] • Provides cross-linked fluoroelastomers with significant curing properties; and

[0160] • Provide cross-linked fluorinated elastomers with improved or similar curing properties (such as curing rate, curing state and cross-linking density).

[0161] The embodiments described herein, along with their various features and advantageous details, are explained with reference to the non-limiting embodiments described below. Descriptions of well-known components and processing techniques are omitted to avoid unnecessarily obscuring the embodiments described herein. The examples used herein are intended only to facilitate understanding of how the embodiments described herein can be practiced, and further to enable those skilled in the art to practice the embodiments described herein. Therefore, the examples should not be construed as limiting the scope of the embodiments described herein.

[0162] The above description of the specific embodiments so fully reveals the general nature of the embodiments described herein that others can readily modify and / or adapt such specific embodiments for various applications by applying present knowledge without departing from the general conception, and therefore, such modifications and alterations should and are intended to be understood within the meaning and scope of equivalents of the disclosed embodiments. It should be understood that the wording or terminology used herein is for descriptive rather than limiting purposes. Therefore, although the embodiments described herein have been based on preferred embodiments, those skilled in the art will recognize that the embodiments described herein can be practiced with modifications within the spirit and scope of the embodiments described herein.

[0163] The use of the terms "at least" or "at least one / one" indicates the use of one / one or more / multiple elements or ingredients or amounts, as may be used in the embodiments of this disclosure, to achieve one or more desired objectives or results.

[0164] Any discussion of documents, actions, materials, devices, articles, etc., included in this specification is for the purpose of providing context for this disclosure only. This should not be construed as an admission that any or all of these matters constitute part of the prior art or common general knowledge in the relevant field that existed anywhere prior to the priority date of this application.

[0165] The values ​​mentioned for various physical parameters, dimensions or quantities are approximate only, and values ​​higher or lower than those specified for the parameters, dimensions or quantities are contemplated to fall within the scope of this disclosure unless specifically stated to the contrary in the specification.

[0166] While this document places considerable emphasis on the components and component parts of the preferred embodiments, it will be understood that many embodiments can be made and many changes can be made to the preferred embodiments without departing from the principles of this disclosure. These and other changes to the preferred embodiments, as well as other embodiments of this disclosure, will be apparent to those skilled in the art from the disclosure herein, and it should therefore be clearly understood that the foregoing descriptive matters should be interpreted as illustrative only and not as limiting.

Claims

1. A bisphenol-free, safe crosslinking system for fluorinated elastomers, comprising the following components: a) A phase transfer catalyst selected from quaternary ammonium salts or quaternary phosphonium salts; b) Non-bisphenol curing agent; c) Dispersant; d) Processing aids; and e) At least one additive.

2. The bisphenol-free safe crosslinking system according to claim 1, wherein the phase transfer catalyst quaternary ammonium salt is selected from cetyltrimethylammonium chloride, cetyltriethylammonium chloride, hexadecyltrimethylammonium chloride, lauryltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium iodide, cetyltrimethylammonium bromide and cetyltrimethylammonium iodide, or the phase transfer catalyst quaternary phosphonium salt is selected from benzyltriphenylphosphonium chloride, triphenylphosphonium chloride, trimethyl(4-vinylbenzyl)phosphonium chloride and (methoxymethyl)triphenylphosphonium chloride.

3. The bisphenol-free safe crosslinking system according to claim 1, wherein the non-bisphenol curing agent is selected from phloroglucinol (1,3,5-trihydroxybenzene), resorcinol (1,3-dihydroxybenzene), phloroglucinol glucoside, phloroglucinol xanthanate, fenotrol, resorcinol monobenzoate, resorcinol monoacetate, ellagic acid, or mixtures thereof.

4. The bisphenol-free safe crosslinking system according to claim 1, wherein the dispersant is selected from diacetone alcohol, polyethylene glycol 400 (PEG 400), dimethyl sulfoxide (DMSO), dimethylformamide, methanesulfonylmethane, fluorosiloxane and cyclohexanol.

5. The bisphenol-free safe crosslinking system according to claim 1, wherein the processing aid is selected from carnauba wax, beeswax, candelilla wax, or paraffin wax, and the additive is selected from magnesium oxide (MgO), calcium oxide (CaO), barium oxide (BaO), magnesium hydroxide Mg(OH)2, calcium hydroxide Ca(OH)2, and barium hydroxide Ba(OH)2.

6. The crosslinking system for fluorinated elastomers according to claim 1, wherein the amounts are included in the following ranges and order: a. Phase transfer catalysts ranging from 0.1 phr to 2.0 phr; b. Non-bisphenol curing agents ranging from 0.1 phr to 4.0 phr; c.0.2 phr to 3.0 phr of dispersant; Processing aids ranging from 0.5 phr to 5.0 phr; and e. At least one additive from 2.0 phr to 10.0 phr.

7. A method for preparing cross-linked fluorinated elastomers, comprising: a. Mixing the components of the crosslinking system according to claim 1 with a fluorinated elastomer to obtain a first mixture, wherein the first mixture comprises a phase transfer catalyst and a non-bisphenol curing agent; and dispersants; b. Add processing aids and additives to the first mixture to obtain a second mixture; and c. Mature the second mixture to obtain a cross-linked fluorinated elastomer.

8. The method for preparing a crosslinked fluorinated elastomer according to claim 7, wherein the components of the crosslinking system of step b. are added to the premixed fluorinated elastomer at a temperature of 35-70°C for 10-60 minutes.

9. The method for preparing cross-linked fluorinated elastomers according to claim 7, wherein the curing time in step c. is 10-50 hours.

10. A crosslinked fluorocarbon-based fluoroelastomer, comprising: A non-bisphenol curing agent with a curing rate of 0.1 phr to 4.0 phr, wherein the non-bisphenol curing agent is selected from phloroglucinol, resorcinol, phloroglucinol derivatives, resorcinol derivatives, ellagic acid and mixtures thereof.

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