Preparation method of chlorine-free and fluorine-free combined vulcanizing agent and application of chlorine-free and fluorine-free combined vulcanizing agent in preparation of fluorine rubber

Abstract

The invention discloses a preparation method of a chlorine-free and fluorine-free combined vulcanizing agent, which comprises the following steps: a) adding benzyl triphenyl phosphorus chloride and an organic solvent into a reaction kettle, and heating and refluxing to completely dissolve the benzyl triphenyl phosphorus chloride; b) slowly adding strong base and an organic solvent into the solution in the step a), and reacting for 2-3 hours; c) adding organic acid into the mixed solution in the step b to neutralize the pH value to 7.5-9; d) adding a bisphenol vulcanizing agent into the reaction system in the step c, and heating and refluxing to obtain a co-melt of benzyltriphenylphosphine hydroxide and the bisphenol vulcanizing agent; e) heating the reactant obtained in the step d to remove the solvent, and repeatedly washing until the detected chloride ion content in the water layer at the upper part is lower than 5ppm; and f) after moisture removal, granulating to obtain the uniform semitransparent granular chlorine-free fluorine combined vulcanizing agent. The fluorine combined vulcanizing agent with the chlorine ion content of less than 5 ppm and stable high-temperature performance is provided, and fluororubber produced and prepared by adopting the fluorine combined vulcanizing agent is very friendly to electronic products.

Description

Technical Field

[0001] This invention relates to the field of fluororubber technology, and more specifically to a method for preparing a chlorine-free fluoropolymer and its application. Background Technology

[0002] Fluororubber is widely used in semiconductors, aerospace, and automotive industries due to its excellent high-temperature resistance and chemical corrosion resistance. Using bisphenols as vulcanizing agents for fluororubber is a mature technology. This system requires a strong alkaline catalyst / accelerator to activate the bisphenol anion, which then attacks the active sites on the fluororubber backbone for cross-linking. Traditional accelerators are chlorinated quaternary phosphonium or quaternary ammonium salts, such as benzyltriphenylphosphine chloride, triphenylbenzylphosphine chloride, and benzyltriphenylammonium chloride. The problem with these chlorine-containing accelerators is that residual chloride ions in the vulcanized rubber may migrate and precipitate, leading to corrosion of electronic components, rusting of metal parts, or contamination in environments requiring extremely high purity (such as semiconductors, pharmaceuticals, and biomedicine). Specifically: 1) Corrosion risk: Chloride ions migrate to the material surface, causing electrochemical corrosion of the contacting metal parts (such as copper wires in semiconductor equipment). 2) Pollution sensitivity: Chloride ions >5 ppm in electronic components can cause short circuits (SEMI F57 standard requires <100 ppb). 3) Long-term aging performance deterioration: At high temperatures, chloride ions catalyze the degradation of the polymer backbone, and the compression set increases by more than 30%.

[0003] Therefore, developing a method for preparing a chlorine-free fluoropolymer vulcanizing agent that combines ultra-high purity, excellent vulcanization performance, and industrial feasibility has become a core requirement for high-end applications of fluororubber. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a chlorine-free fluoropolymer and its application in the preparation of fluororubber. This invention provides a fluoropolymer with a chloride ion content of <5 ppm and stable high-temperature performance. Fluororubber prepared using this fluoropolymer is highly compatible with electronic products and exhibits good durability, making it particularly suitable for applications such as semiconductors where strict chloride ion content requirements exist.

[0005] The technical solution adopted by this invention to solve the technical problem is: a method for preparing a chlorine-free fluorinated bisulfide agent, the preparation method comprising the following steps: Step a) Add benzyltriphenylphosphine chloride and organic solvent to the reaction vessel, heat and stir, and completely dissolve benzyltriphenylphosphine chloride under reflux. Step b) Slowly add a strong base and an organic solvent to the solution from step a), and react for 2-3 hours; Step c) Add an appropriate amount of organic acid to the reaction mixture from step b) to neutralize the pH of the reaction system to 7.5-9; Step d) Add bisphenol-based vulcanizing agent to the reaction system of step c), continue heating under reflux, and after forming a homogeneous solution, continue the reaction for 1 to 3 hours to obtain a eutectic mixture of benzyltriphenylphosphine hydroxide and bisphenol-based vulcanizing agent; Step e) Heat the reactants obtained in step d) to remove the solvent, and then wash them repeatedly with water until the chloride ion content detected in the upper water layer is less than 5 ppm; Step f) After heating and vacuuming to remove moisture, raise the temperature to 120~130℃ and stir for 20~40 minutes. The material is then granulated into uniform semi-transparent particles, which are chlorine-free fluorocarbons.

[0006] Further, in steps a) and b), the organic solvent includes ethanol, propanol, and acetone.

[0007] Further, in step b), the strong base includes sodium hydroxide and potassium hydroxide, and the molar ratio of the amount of the strong base to benzyltriphenylphosphine chloride is 1.2~1.05:1; in step c), the organic acid includes oxalic acid and citric acid.

[0008] Furthermore, based on the molar ratio, the ratio of benzyltriphenylphosphine chloride to bisphenol vulcanizing agent is 1:3.5~6.

[0009] Further, in step d), the bisphenol-based vulcanizing agent includes one or more of bisphenol A, bisphenol S, and bisphenol AF.

[0010] Further, in step e), the number of water washes is 3 to 5 times. During the water wash process, the water is first washed with distilled water 2 to 3 times, and then washed with deionized water 2 to 3 times.

[0011] Another technical solution claimed by this invention is the application of a chlorine-free fluoropolymer in the preparation of fluororubber, wherein the fluororubber comprises, by weight percentage: 100 parts of fluororubber raw rubber, 1-8 parts of chlorine-free fluoropolymer, 1-10 parts of acid scavenger, 4-20 parts of calcium hydroxide, and 10-40 parts of reinforcing filler.

[0012] Furthermore, the fluororubber raw rubber includes binary or ternary fluororubber polymerized from two or three monomers selected from vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene; the acid absorbent is light magnesium oxide or active magnesium oxide, wherein the activity value of the active magnesium oxide is 50-180.

[0013] Furthermore, the fluororubber is primarily used in semiconductor seals or other environments where chlorine cannot be present.

[0014] The beneficial effects of this invention are as follows: Compared with the prior art, the method for preparing a chlorine-free fluoropolymer vulcanizing agent and its application in the preparation of fluororubber provided by this invention results in a chlorine-free fluoropolymer vulcanizing agent with a chloride ion content of less than 5 ppm, which is suitable for semiconductor seals or other elastomer products with strict requirements for chloride ion content; since the eutectic mixture of benzyltriphenylphosphine hydroxide and bisphenol vulcanizing agent is prepared in advance, only one feeding is required during the fluororubber vulcanization process, making the operation simpler and more efficient, and reducing the possibility of dust pollution. Detailed Implementation

[0015] The present invention will be further illustrated below with specific embodiments. However, these examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0016] Example 1 A method for preparing a chlorine-free fluorocarbon disulfide, the method comprising the following steps: Step a) Add benzyltriphenylphosphine chloride and ethanol to the reaction vessel, heat and stir, and completely dissolve benzyltriphenylphosphine chloride under reflux. Step b) Slowly add an ethanol solution of sodium hydroxide to the solution from step a), and react for 2-3 hours; Step c) Add oxalic acid to the reaction mixture from step b) to neutralize the pH of the reaction system to 7.5-9; Step d) Add bisphenol AF to the reaction system of step c), continue heating to melt, and after forming a homogeneous solution, continue the reaction for 2 hours to obtain a eutectic mixture of benzyltriphenylphosphine hydroxide and bisphenol AF; Step e) After removing the solvent from the reactants obtained in step d), wash them three times with distilled water, combine the organic phases, and then wash them twice with deionized water. The detected chloride ion content is less than 5 ppm. Step f) After heating to remove moisture, raise the temperature to 120~130℃ and stir for 30 minutes. The material is then granulated into uniform semi-transparent particles, which are chlorine-free fluorocarbons (named V-5).

[0017] In the above preparation, the molar ratio of benzyltriphenylphosphine chloride to bisphenol AF is 1:4.63.

[0018] The preparation principle of the above-mentioned chlorine-free fluorocarbon disulfide is as follows: 1) Benzyltriphenylphosphine chloride (BPP) undergoes a strong base reaction in the liquid phase to remove chloride ions, transforming into benzyltriphenylphosphine hydroxide, with the following chemical formula: Ph3-PCH2-C6H5•Cl+OH − ⟶Ph3-PCH2-C6H5•OH+Cl − ; 2) Benzyltriphenylphosphine hydroxide and bisphenol AF fully form a eutectic under heating conditions. It is insoluble in water and can remove impurities such as sodium chloride and sodium oxalate by washing with water, reducing the chloride ion content to below 5 ppm.

[0019] The V-5 prepared above was applied to the preparation of fluororubber, with the following specific composition: 100 parts of fluororubber type 26 (50 Mooney), 2.5 parts of chlorine-free fluoropolymer V-5, 3 parts of magnesium oxide (150 active), 6 parts of calcium hydroxide, and 30 parts of carbon black 990. The preparation process was as follows: Fluororubber raw rubber was added to a mixer and plasticized for 1-2 minutes. Cooling water was turned on, and the remaining materials were added and mixed for 2-3 minutes. Then, the mixture was transferred to a two-roll mill and passed through it 10 times. The sheet was cooled and left to stand for 24 hours. The mixture was then passed through it 8-10 times and cooled to obtain a compound rubber sheet. The fluororubber sample was then subjected to performance testing according to the corresponding standard sample requirements, with a first-stage vulcanization at 170℃ for 10 minutes and a second-stage vulcanization at 230℃ for 16 hours. The test results are shown in Table 1.

[0020] Example 2 In this embodiment, the preparation method of fluorinated bicarbonate is the same as in Example 1.

[0021] In the preparation of fluororubber, the amount of V-5 was adjusted to 2 parts, and the rest were the same as in Example 1.

[0022] Example 3 In this embodiment, the preparation method of fluorinated bicarbonate is the same as in Example 1.

[0023] In the preparation of fluororubber, the raw fluororubber was replaced with fluororubber type 246 (fluorine content of 68.5%, 60 Mooney content), the amount of which remained unchanged, and the rest was the same as in Example 1.

[0024] Example 4 In this embodiment, during the preparation of the fluorinated compound, the molar ratio of benzyltriphenylphosphine chloride to bisphenol AF was adjusted to 1:5.5. All other steps were the same as in Example 1.

[0025] Example 5 In this embodiment, the molar ratio of benzyltriphenylphosphine chloride to bisphenol AF was adjusted to 1:3.6 during the preparation of the fluorinated compound. All other steps were the same as in Example 1.

[0026] Comparative Example 1 The fluororubber was prepared with the following specific composition: 100 parts of fluororubber type 26 (50 Mooney), 2 parts of bisphenol AF, 0.5 parts of benzyltriphenylphosphine chloride BPP, 3 parts of magnesium oxide (150 active), 6 parts of calcium hydroxide, and 30 parts of carbon black 990. The preparation process was the same as in Example 1.

[0027] Comparative Example 2 The fluororubber was prepared with the following specific composition: 100 parts of fluororubber type 26 (50 Mooney), 2.5 parts of fluoropolymer VC-5, 3 parts of magnesium oxide (150 active), 6 parts of calcium hydroxide, and 30 parts of carbon black 990. The preparation process was the same as in Example 1. The fluoropolymer VC-5 was a product of DuPont.

[0028] Comparative Example 3 The difference from Example 1 is that no eutectic is prepared, and steps a to c are the same as in Example 1. The product from step c is washed and dehydrated according to step e. In the preparation of fluororubber, benzyltriphenylphosphine hydroxide obtained in step e is added directly. The specific composition is as follows: 100 parts of fluororubber type 26, 0.47 parts of benzyltriphenylphosphine hydroxide, 2 parts of bisphenol AF, 3 parts of magnesium oxide (150 active), 6 parts of calcium hydroxide, and 30 parts of carbon black 990.

[0029] The rest is the same as in Example 1.

[0030] Table 1 shows the performance test data of the fluororubber obtained in each embodiment and comparative example.

[0031]

[0032] As can be seen from the table above, V-5 can be well applied in both binary and ternary fluororubber. Under the same formulation, V-5 has extremely low chloride ion content, and also achieves higher strength, lower compression set and better aging performance.

[0033] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A method for preparing a chlorine-free fluorocarbon disulfide, characterized in that: The preparation method includes the following steps: Step a) Add benzyltriphenylphosphine chloride and organic solvent to the reaction vessel, heat and stir, and completely dissolve benzyltriphenylphosphine chloride under reflux. Step b) Slowly add a strong base and an organic solvent to the solution from step a, and react for 2-3 hours; Step c) Add an appropriate amount of organic acid to the reaction mixture from step b to neutralize the pH of the reaction system to 7.5-9; Step d) Add bisphenol-based vulcanizing agent to the reaction system of step c, continue heating under reflux, and after forming a homogeneous solution, continue the reaction for 1 to 3 hours to obtain a eutectic mixture of benzyltriphenylphosphine hydroxide and bisphenol-based vulcanizing agent; Step e) The reactants obtained in step d are heated to remove the solvent, and then repeatedly washed with water until the chloride ion content detected in the upper aqueous layer is less than 5 ppm; Step f) After heating and vacuuming to remove moisture, raise the temperature to 120~130℃ and stir for 20~40 minutes. The material is then granulated into uniform semi-transparent particles, which are chlorine-free fluorocarbons.

2. The method for preparing a chlorine-free fluorocarbon disulfide as described in claim 1, characterized in that: In steps a and b, the organic solvent includes ethanol, propanol, and acetone.

3. The method for preparing a chlorine-free fluorocarbon disulfide as described in claim 1, characterized in that: In step b, the strong base includes sodium hydroxide and potassium hydroxide, and the molar ratio of the strong base to benzyltriphenylphosphine chloride is 1.2~1.05:1; in step c, the organic acid includes oxalic acid and citric acid.

4. The method for preparing a chlorine-free fluorocarbon disulfide as described in claim 1, characterized in that: The molar ratio of benzyltriphenylphosphine chloride to bisphenol vulcanizing agent is 1:3.5~6.

5. A method for preparing a chlorine-free fluorocarbon disulfide as described in claim 1 or 4, characterized in that: In step d, the bisphenol-based vulcanizing agent includes one or more of bisphenol A, bisphenol S, and bisphenol AF.

6. The method for preparing a chlorine-free fluorocarbon disulfide as described in claim 1, characterized in that: In step e, the number of water washes is 3 to 5 times. During the water wash process, the water is first washed with distilled water 2 to 3 times, and then washed with deionized water 2 to 3 times.

7. The application of a chlorine-free fluoropolymer vulcanizing agent as described in claim 1 in the preparation of fluororubber, characterized in that: The composition of the fluororubber, by weight percentage, includes: 100 parts of fluororubber raw rubber, 1-8 parts of chlorine-free fluoropolymer vulcanizing agent, 1-10 parts of acid absorber, 4-20 parts of calcium hydroxide, and 10-40 parts of reinforcing filler.

8. The application of the chlorine-free fluoropolymer vulcanizing agent as described in claim 7 in the preparation of fluororubber, characterized in that: The fluororubber raw material includes binary or ternary fluororubber polymerized from two or three monomers selected from vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene; the acid absorbent is light magnesium oxide or active magnesium oxide, wherein the activity value of the active magnesium oxide is 50-180.

9. The application of a chlorine-free fluoropolymer vulcanizing agent as described in claim 7 in the preparation of fluororubber, characterized in that: The fluororubber is mainly used in semiconductor seals or other environments where chlorine cannot be present.

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