A silsesquioxane-modified ethylene-chlorotrifluoroethylene resin

Abstract

The present invention discloses a silsesquioxane-modified ethylene-chlorotrifluoroethylene resin, which is prepared by copolymerizing a compound represented by the following structural formula (I), chlorotrifluoroethylene and ethylene monomers, wherein: R is -O(CX2) n O(CH2) m OCH=CH2, X is independently selected from H, F, Cl, or Br, n is an integer from 1 to 5, and m is an integer from 1 to 5. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin prepared in the present invention has good hardness and excellent scratch resistance and is suitable for use as a coating in chemical container linings or self-supporting pipelines.

Description

Technical Field

[0001] The present invention relates to the field of polymers, in particular to silsesquioxane-modified ethylene-chlorotrifluoroethylene resin. Background Art

[0002] Ethylene-chlorotrifluoroethylene copolymer (ECTFE or F30) is a thermoplastic fluorinated copolymer with extraordinary corrosion resistance to the vast majority of inorganic and organic chemicals and organic solvents. Currently, no solvent has been found that can dissolve ECTFE or cause stress cracking below 120°C. Compared with other thermoplastic copolymers, ECTFE is particularly resistant to chlorine and chlorine derivatives at high temperatures. Its chemical corrosion resistance is comparable to that of perfluoropolymers and better than that of polyvinylidene fluoride. It has good toughness, high hardness, and outstanding impact resistance. It shows better wear and corrosion resistance than polytetrafluoroethylene and tetrafluoroethylene-hexafluoropropylene copolymer. Therefore, ECTFE can be used as heavy-duty corrosion protection for the interior of some chemical containers.

[0003] In order to further improve the hardness of ECTFE powder coatings and prevent scratches and mechanical damage when scratched by sharp objects, the existing technology has made the following efforts:

[0004] Japanese patent JP03163147A discloses a fluorine-containing copolymer composition, wherein a flexible fluorine-containing resin is grafted onto ECTFE to obtain a modified ECTFE having good flexibility and plasticity.

[0005] Japanese patent JP04227777A discloses a coating composition for sliding parts, wherein the composition is obtained by adding polyphenylene sulfide resin, aromatic polyester resin, organopolysiloxane elastomer or fluoroelastomer to ECTFE, thereby obtaining a coating with low friction, excellent wear resistance, heat resistance, toughness and impact resistance, and which will not break or peel off during post-processing.

[0006] Chinese patent CN112480296A discloses a hydrophilically modified ethylene-chlorotrifluoroethylene copolymer, wherein the copolymer is modified with RX-CH=CRY-COOCH3 to form ethylene-chlorotrifluoroethylene copolymer. The modified ECTFE has excellent mechanical properties and thermal stability.

[0007] Chinese patent CN106832077A discloses an ECTFE fluororesin with a self-crosslinking structure. The fluororesin is prepared by modifying ECTFE with alkoxymethyl (alkyl) acrylamide and a modifying monomer A. The modified ECTFE can be used as an anti-corrosion coating.

[0008] However, the above-mentioned existing technologies for modifying ECTFE focus on its plasticity, wear resistance, hydrophilicity, and corrosion resistance, without specifically addressing toughness, hardness, or scratch resistance. When ECTFE resin is used as an internal coating for production equipment, it inevitably experiences powder erosion, necessitating improvements to enhance its hardness and scratch resistance. Summary of the Invention

[0009] The present invention aims to provide a silsesquioxane-modified ethylene-chlorotrifluoroethylene resin, which has good hardness and scratch resistance.

[0010] In order to achieve the purpose, the technical solution of the present invention is as follows:

[0011] A silsesquioxane-modified ethylene-chlorotrifluoroethylene resin is prepared by copolymerizing monomers including a compound represented by structural formula (I), chlorotrifluoroethylene, and ethylene. The compound represented by structural formula (I) is as follows:

[0012]

[0013] Where: R is -O(CX2) n O(CH2) m OCH=CH2, X is independently selected from H, F, Cl or Br, n=an integer of 1 to 5, and m=an integer of 1 to 5.

[0014] In the compound represented by structural formula (I) of the present invention, X is independently selected from H, F, Cl or Br, n = an integer of 1 to 5, and m = an integer of 1 to 5; preferably, X is independently selected from H, F or Cl, n = an integer of 2 to 4, and m = an integer of 1 to 3; more preferably, X is independently selected from H or F, n = an integer of 2 to 3, and m = an integer of 1 to 2.

[0015] The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin of the present invention comprises 0.1-15 wt% of the compound structural unit represented by structural formula (I), 30-70 wt% of chlorotrifluoroethylene structural units and 30-70 wt% of ethylene structural units; preferably, the silsesquioxane-modified ethylene-chlorotrifluoroethylene resin comprises 0.1-12 wt% of the compound structural unit represented by structural formula (I), 40-60 wt% of chlorotrifluoroethylene structural units and 40-60 wt% of ethylene structural units; more preferably, the silsesquioxane-modified ethylene-chlorotrifluoroethylene resin comprises 0.5-10 wt% of the compound structural unit represented by structural formula (I), 45-55 wt% of chlorotrifluoroethylene structural units and 45-55 wt% of ethylene structural units.

[0016] The present invention also provides a method for preparing a silsesquioxane-modified ethylene-chlorotrifluoroethylene resin, the method comprising the following steps:

[0017] (1) adding high-purity water, a dispersant, a pH buffer, a chain transfer agent, and a compound represented by structural formula (I) into a reactor, evacuating the reactor and replacing the reactor with nitrogen until the oxygen content in the reactor is less than 30 ppm;

[0018] (2) The temperature inside the reactor is raised to 10-90°C;

[0019] (3) adding chlorotrifluoroethylene, ethylene and initiator into the reactor;

[0020] (4) The reaction is continued for 1.5 to 6 hours, and then the reaction is terminated. The product is washed and dried to obtain silsesquioxane-modified ethylene-chlorotrifluoroethylene resin.

[0021] Preferably, the preparation method of the silsesquioxane-modified ethylene-chlorotrifluoroethylene resin comprises the following steps:

[0022] (1) High-purity water, a dispersant, a pH buffer, a chain transfer agent, and a compound represented by structural formula (I) are added to a reactor, wherein water is used as a medium, and per 100 parts by mass of the aqueous medium, 0.1 to 15 parts by mass of the compound represented by structural formula (I), 0.01 to 5 parts by mass of the dispersant, 0.01 to 2 parts by mass of the pH buffer, and 0.01 to 5 parts by mass of the chain transfer agent are contained. The reactor is evacuated and replaced with nitrogen until the oxygen content in the reactor is less than 30 ppm;

[0023] (2) maintaining the internal temperature of the reactor at 10 to 50° C., adding chlorotrifluoroethylene into the reactor in an amount of 30 to 70 parts by weight based on the total amount of chlorotrifluoroethylene and ethylene;

[0024] (3) raising the temperature of the reactor to a constant temperature of 30 to 90° C., adding ethylene to the reactor until the pressure in the reactor is 1 to 6 MPa, adding 0.01 to 5 parts by mass of an initiator to the reactor to initiate the reaction, and continuously adding ethylene to the reactor to maintain a constant pressure in the reactor;

[0025] (4) After the reaction lasts for 1.5 to 6 hours, the reaction is terminated, and the product is washed and dried to obtain silsesquioxane-modified ethylene-chlorotrifluoroethylene resin.

[0026] The dispersant used in the present invention is a commonly used dispersant in the art. Preferably, the dispersant is selected from one or more of perfluorooctanoic acid ammonium salt or alkali metal salt, hexafluoropropylene oxide oligomer carboxylate ammonium salt or alkali metal salt, polyvinyl alcohol and hydroxypropyl methylcellulose.

[0027] The pH buffer used in the present invention is a commonly used buffer in the art. Preferably, the pH buffer is selected from one or more of sodium dihydrogen phosphate, potassium dihydrogen phosphate and sodium tetraborate.

[0028] The initiator used in the present invention is a commonly used initiator in the art. Preferably, the initiator is one or more selected from potassium persulfate, ammonium persulfate, sodium persulfate, potassium persulfate-sodium bisulfite, ammonium persulfate-sodium bisulfite and diisopropyl peroxydicarbonate.

[0029] The chain transfer agent used in the present invention is a commonly used chain transfer agent in the art. Preferably, the chain transfer agent is selected from one or more of carbon tetrachloride, ethyl acetate, ethylene glycol, diethyl malonate, isopentane and chloroform.

[0030] In the preparation method provided by the present invention, preferably, in the step (1), per 100 parts by mass of the aqueous medium, 0.5 to 10 parts by mass of the compound represented by structural formula (I), 0.05 to 3 parts by mass of a dispersant, 0.05 to 1 parts by mass of a pH buffer, and 0.05 to 3 parts by mass of a chain transfer agent are contained; in the step (2), the internal temperature of the reactor is maintained at 10 to 30° C., and 45 to 55 parts by mass of chlorotrifluoroethylene are added to the reactor; in the step (3), the temperature of the reactor is increased to a constant temperature of 40 to 80° C., ethylene is added to the reactor until the pressure in the reactor is 2 to 5 MPa, and 0.05 to 2 parts by mass of an initiator are added to the reactor to initiate the reaction; in the step (4), the reaction is continued for 1.5 to 4 hours, and then the reaction is terminated.

[0031] The present invention also provides an application of a silsesquioxane-modified ethylene-chlorotrifluoroethylene resin. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin is used as a coating for the lining of a chemical container or a self-supporting pipeline.

[0032] Compared with the prior art, the technical solution of the present invention has the following technical effects:

[0033] The invention uses silsesquioxane to improve ethylene-chlorotrifluoroethylene, and the prepared improved ethylene-chlorotrifluoroethylene resin has excellent hardness and scratch resistance. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements and equivalents within the scope of the claims.

[0035] Example 1

[0036] A 5L stainless steel autoclave equipped with mechanical stirring, temperature control, circulating heating, and circulating cooling water was cleaned and then charged with 3L of high-purity water, 2g of polyvinyl alcohol, 2g of disodium hydrogen phosphate, 10g of carbon tetrachloride, and 300g of a silsesquioxane represented by structural formula (I) (X selected from F, n=2, m=1). The atmosphere was replaced with nitrogen and vacuum three times. The oxygen content in the reactor was measured to be below 30ppm, and the reactor was evacuated until the pressure in the reactor reached -0.1MPa. 1250g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 65°C. Ethylene was added to the reactor via a compressor until the pressure in the reactor reached 3.5MPa. 150g of an aqueous solution containing 2.5g of potassium persulfate was added to the reactor via a metering pump to initiate polymerization. Ethylene was continuously added to the reactor to maintain the pressure in the reactor at 3.5MPa. After the reaction continued for 5 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The material in the reaction kettle was placed in a centrifuge, dehydrated, washed several times with hot high-purity water, and vacuum-dried at 100-120° C. for 8 hours to obtain 1215 g of modified ethylene-chlorotrifluoroethylene resin.

[0037] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluorochloroethylene resin was 46.9%, the mass percentage of ethylene structural unit was 46.2%, and the mass percentage of silsesquioxane structural unit was 6.9%.

[0038] Example 2

[0039] A 5L stainless steel autoclave equipped with mechanical stirring, temperature control, circulating heating, and circulating cooling water was cleaned and charged with 3L of high-purity water, 2g of hydroxypropyl methylcellulose, 2g of disodium hydrogen phosphate, 7g of ethyl acetate, and 200g of a silsesquioxane of structural formula (I) (X selected from F, n=2, m=1). The atmosphere was replaced with nitrogen and vacuum three times. The oxygen content in the reactor was measured to be below 30ppm. The reactor was then evacuated to a pressure of -0.1MPa. 1250g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 65°C. Ethylene was added to the reactor via a compressor until the pressure reached 3.5MPa. 150g of an aqueous solution containing 2.4g of ammonium persulfate was added to the reactor via a metering pump to initiate polymerization. Ethylene was continuously added to the reactor to maintain the pressure at 3.5MPa. After the reaction continued for 5 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The material in the reaction kettle was placed in a centrifuge, dehydrated, washed several times with hot high-purity water, and vacuum-dried at 100-120° C. for 8 hours to obtain 1221 g of modified ethylene-chlorotrifluoroethylene resin.

[0040] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluorochloroethylene resin was 48.5%, the mass percentage of ethylene structural unit was 47.0%, and the mass percentage of silsesquioxane structural unit was 4.5%.

[0041] Example 3

[0042] A 5L stainless steel high-pressure reactor equipped with mechanical stirring, temperature control device, circulating heating, and circulating cooling water was cleaned, and 3L of high-purity water, 2.5g of polyvinyl alcohol, 2g of disodium hydrogen phosphate, 10g of carbon tetrachloride, 150g of an aqueous solution containing 2.3g of potassium persulfate, and 240g of silsesquioxane represented by structural formula (I) (X is selected from F, n=2, m=1) were added to the reactor. Nitrogen and vacuum replacement were performed three times. The oxygen content in the reactor was measured to be below 30ppm, and the reactor was continuously evacuated until the pressure in the reactor was -0.1MPa. 1250 g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 45° C. Ethylene was then added to the reactor via a compressor until the pressure in the reactor reached 2.6 MPa. 150 g of an aqueous solution containing 0.45 g of sodium bisulfite was then added to the reactor via a metering pump to initiate a polymerization reaction. Ethylene was continuously added to the reactor to maintain the pressure in the reactor at 2.6 MPa. After the reaction continued for 5 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The contents of the reactor were placed in a coagulation drum, coagulated and dehydrated, and then washed several times with hot high-purity water. The mixture was then vacuum dried at 100-120° C. for 8 hours to obtain 1229 g of a modified ethylene-chlorotrifluoroethylene resin.

[0043] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluoroethylene resin was 48.0%, the mass percentage of ethylene structural unit was 46.9%, and the mass percentage of silsesquioxane structural unit was 5.1%.

[0044] Example 4

[0045] A 5L stainless steel high-pressure reactor equipped with mechanical stirring, temperature control device, circulating heating, and circulating cooling water was cleaned, and 3L of high-purity water, 2.5g of hexafluoropropylene oxide oligomer carboxylate ammonium salt, 2g of sodium tetraborate, 10g of diethyl malonate, 150g of an aqueous solution containing 2.0g of ammonium persulfate, and 150g of silsesquioxane represented by structural formula (I) (X is selected from F, n=2, m=1) were added to the reactor. Nitrogen and vacuum replacement were performed three times. The oxygen content in the reactor was measured to be below 30ppm, and the reactor was continuously evacuated until the pressure in the reactor was -0.1MPa. 1250 g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 45° C. Ethylene was then added to the reactor via a compressor until the pressure in the reactor reached 2.6 MPa. 150 g of an aqueous solution containing 0.45 g of sodium bisulfite was then added to the reactor via a metering pump to initiate a polymerization reaction. Ethylene was continuously added to the reactor to maintain the pressure in the reactor at 2.6 MPa. After the reaction continued for 5 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The contents of the reactor were placed in a coagulation drum, coagulated and dehydrated, and then washed several times with hot high-purity water. The mixture was then vacuum dried at 100-120° C. for 8 hours to obtain 1210 g of a modified ethylene-chlorotrifluoroethylene resin.

[0046] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluoroethylene resin was 48.9%, the mass percentage of ethylene structural unit was 47.4%, and the mass percentage of silsesquioxane structural unit was 3.7%.

[0047] Example 5

[0048] A 5L stainless steel high-pressure reactor equipped with mechanical stirring, temperature control device, circulating heating, and circulating cooling water was cleaned, and 3L of high-purity water, 2g of ammonium perfluorooctanoate, 2g of potassium dihydrogen phosphate, 10g of ethylene glycol, 150g of an aqueous solution containing 2.3g of potassium persulfate, and 270g of silsesquioxane represented by structural formula (I) (X is selected from F, n=2, m=1) were added to the reactor. Nitrogen and vacuum replacement were performed three times. The oxygen content in the reactor was measured to be below 30ppm, and the vacuum was continued until the pressure in the reactor was -0.1MPa. 1250 g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 45° C. Ethylene was then added to the reactor via a compressor until the pressure in the reactor reached 2.6 MPa. 150 g of an aqueous solution containing 0.45 g of sodium bisulfite was then added to the reactor via a metering pump to initiate a polymerization reaction. Ethylene was continuously added to the reactor to maintain the pressure in the reactor at 2.6 MPa. After the reaction continued for 5 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The contents of the reactor were placed in a coagulation drum, coagulated and dehydrated, and then washed several times with hot high-purity water. The mixture was then vacuum dried at 100-120° C. for 8 hours to obtain 1207 g of a modified ethylene-chlorotrifluoroethylene resin.

[0049] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluoroethylene resin was 49.8%, the mass percentage of ethylene structural unit was 48.5%, and the mass percentage of silsesquioxane structural unit was 5.7%.

[0050] Example 6

[0051] A 5L stainless steel high-pressure reactor equipped with mechanical stirring, temperature control device, circulating heating, and circulating cooling water was cleaned, and 3L of high-purity water, 2.7g of hexafluoropropylene oxide oligomer carboxylate ammonium salt, 2g of sodium tetraborate, 5g of isopentane, 150g of an aqueous solution containing 2.3g of potassium persulfate, and 150g of silsesquioxane represented by structural formula (I) (X is selected from F, n=2, m=1) were added to the reactor. Nitrogen and vacuum replacement were performed three times. The oxygen content in the reactor was measured to be below 30ppm, and the reactor was continuously evacuated until the pressure in the reactor was -0.1MPa. 1250 g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 45° C. Ethylene was then added to the reactor via a compressor until the pressure reached 2.6 MPa. 150 g of an aqueous solution containing 0.45 g of sodium bisulfite was then added to the reactor via a metering pump to initiate a polymerization reaction. Ethylene was continuously added to the reactor to maintain the pressure at 2.6 MPa. After the reaction continued for 5 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The contents of the reactor were placed in a coagulation drum, coagulated and dehydrated, and then washed several times with hot high-purity water. The mixture was then vacuum dried at 100-120° C. for 8 hours to obtain 1213 g of a modified ethylene-chlorotrifluoroethylene resin.

[0052] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of chlorotrifluoroethylene structural units in the modified ethylene-chlorotrifluoroethylene resin was 47.6%, the mass percentage of ethylene structural units was 46.4%, and the mass percentage of silsesquioxane structural units was 6.0%.

[0053] Example 7

[0054] A 5L stainless steel autoclave equipped with mechanical stirring, temperature control, circulating heating, and circulating cooling water was cleaned and then charged with 3L of high-purity water, 2g of hydroxypropyl methylcellulose, 2g of sodium tetraborate, 7g of chloroform, and 240g of a silsesquioxane of structural formula (I) (X selected from F, n=2, m=1). The atmosphere was then replaced with nitrogen and vacuum three times. The oxygen content in the reactor was measured to be below 30 ppm, and the reactor was evacuated until the pressure in the reactor reached -0.1 MPa. 1250g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 55°C. Ethylene was then added to the reactor via a compressor until the pressure in the reactor reached 3.1 MPa. 6.4g of a diisopropyl peroxydicarbonate solution was then added to the reactor via a metering pump to initiate polymerization. Ethylene was continuously added to the reactor to maintain the pressure in the reactor at 3.1 MPa. After the reaction continued for 4 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The material in the reaction kettle was placed in a centrifuge, dehydrated, washed several times with hot high-purity water, and vacuum-dried at 100-120° C. for 8 hours to obtain 1204 g of modified ethylene-chlorotrifluoroethylene resin.

[0055] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluoroethylene resin was 48.1%, the mass percentage of ethylene structural unit was 47.0%, and the mass percentage of silsesquioxane structural unit was 4.9%.

[0056] Example 8

[0057] A 5L stainless steel autoclave equipped with mechanical stirring, temperature control, circulating heating, and circulating cooling water was cleaned and then charged with 3L of high-purity water, 2.5g of polyvinyl alcohol, 2g of sodium tetraborate, 7g of chloroform, and 210g of a silsesquioxane of structural formula (I) (X selected from F, n=2, m=1). The atmosphere was replaced with nitrogen and vacuum three times. The oxygen content in the reactor was measured to be below 30ppm, and the reactor was evacuated until the pressure in the reactor reached -0.1MPa. 1250g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 55°C. Ethylene was added to the reactor via a compressor until the pressure in the reactor reached 3.1MPa. 5.9g of a diisopropyl peroxydicarbonate solution was added to the reactor via a metering pump to initiate polymerization. Ethylene was continuously added to the reactor to maintain the pressure in the reactor at 3.1MPa. After the reaction continued for 4 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The material in the reaction kettle was placed in a centrifuge, dehydrated, washed several times with hot high-purity water, and vacuum-dried at 100-120° C. for 8 hours to obtain 1194 g of modified ethylene-chlorotrifluoroethylene resin.

[0058] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluoroethylene resin was 48.4%, the mass percentage of ethylene structural unit was 47.4%, and the mass percentage of silsesquioxane structural unit was 4.2%.

[0059] Example 9

[0060] A 5L stainless steel autoclave equipped with mechanical stirring, temperature control, circulating heating, and circulating cooling water was cleaned and then charged with 3L of high-purity water, 2g of hydroxypropyl methylcellulose, 2g of sodium tetraborate, 7g of chloroform, and 150g of a silsesquioxane of structural formula (I) (X selected from F, n=2, m=1). The atmosphere was then replaced with nitrogen and vacuum three times. The oxygen content in the reactor was measured to be below 30 ppm, and the reactor was evacuated until the pressure inside the reactor reached -0.1 MPa. 1250g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 55°C. Ethylene was then added to the reactor via a compressor until the pressure inside the reactor reached 3.1 MPa. 5.9g of a diisopropyl peroxydicarbonate solution was then added to the reactor via a metering pump to initiate polymerization. Ethylene was continuously added to the reactor to maintain the pressure inside the reactor at 3.1 MPa. The reaction proceeded continuously for 4 hours, at which time the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The material in the reactor was placed in a centrifuge, dehydrated, washed several times with hot high-purity water, and vacuum-dried at 100-120° C. for 8 hours to obtain 1198 g of modified ethylene-chlorotrifluoroethylene resin.

[0061] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluoroethylene resin was 48.9%, the mass percentage of ethylene structural unit was 47.8%, and the mass percentage of silsesquioxane structural unit was 3.3%.

[0062] Example 10

[0063] A 5L stainless steel high-pressure reactor equipped with mechanical stirring, temperature control device, circulating heating, and circulating cooling water was cleaned, and 3L of high-purity water, 2.7g of hexafluoropropylene oxide oligomer carboxylate ammonium salt, 2g of sodium tetraborate, 10g of diethyl malonate, 150g of an aqueous solution containing 2.3g of potassium persulfate, and 150g of silsesquioxane represented by structural formula (I) (X is selected from F, n=2, m=1) were added to the reactor. Nitrogen and vacuum replacement were performed three times. The oxygen content in the reactor was measured to be below 30ppm, and the reactor was continuously evacuated until the pressure in the reactor was -0.1MPa. 1250 g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 60° C. Ethylene was then added to the reactor via a compressor until the pressure in the reactor reached 3.3 MPa. 150 g of an aqueous solution containing 0.45 g of sodium bisulfite was then added to the reactor via a metering pump to initiate a polymerization reaction. Ethylene was continuously added to the reactor to maintain the pressure in the reactor at 3.3 MPa. After the reaction continued for 5 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The contents of the reactor were placed in a coagulation drum, coagulated and dehydrated, and then washed several times with hot high-purity water. The mixture was then vacuum dried at 100-120° C. for 8 hours to obtain 1237 g of a modified ethylene-chlorotrifluoroethylene resin.

[0064] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of trifluoroethylene structural unit in the modified ethylene-trifluoroethylene resin was 48.8%, the mass percentage of ethylene structural unit was 47.5%, and the mass percentage of silsesquioxane structural unit was 3.7%.

[0065] Comparative Example 1

[0066] A 5L stainless steel autoclave equipped with mechanical stirring, temperature control, circulating heating, and circulating cooling water was cleaned and then charged with 3L of high-purity water, 2.5g of hexafluoropropylene oxide oligomer carboxylate ammonium salt, 2g of sodium tetraborate, 10g of diethyl malonate, and 150g of an aqueous solution containing 2.0g of ammonium persulfate. The reactor was then purged with nitrogen and vacuum three times. The oxygen content in the reactor was measured to be below 30ppm, and the reactor was evacuated until the pressure inside the reactor reached -0.1MPa. 1250g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 45°C. Ethylene was added to the reactor via a compressor until the pressure inside the reactor reached 2.6MPa. 150g of an aqueous solution containing 0.45g of sodium bisulfite was added to the reactor via a metering pump to initiate polymerization. Ethylene was continuously added to the reactor to maintain the pressure inside the reactor at 2.6MPa. After the reaction continued for 5 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The material in the reactor was placed in a coagulation barrel, coagulated and dehydrated, washed with hot high-purity water several times, and vacuum dried at 100-120°C for 8 hours to obtain 1231 g of ethylene-chlorotrifluoroethylene resin.

[0067] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of chlorotrifluoroethylene structural units in the ethylene-chlorotrifluoroethylene resin was 50.6%, and the mass percentage of ethylene structural units was 49.4%.

[0068] Comparative Example 2

[0069] A 5L stainless steel autoclave equipped with mechanical stirring, temperature control, circulating heating, and circulating cooling water was cleaned and then charged with 3L of high-purity water, 2g of hydroxypropyl methylcellulose, 2g of sodium tetraborate, and 7g of chloroform. The atmosphere was replaced with nitrogen and vacuum three times. The oxygen content in the reactor was measured to be below 30ppm, and the reactor was evacuated until the pressure reached -0.1MPa. 1250g of chlorotrifluoroethylene was added to the reactor via a metering device. The reactor was stirred and heated to 55°C. Ethylene was added to the reactor via a compressor until the pressure reached 3.1MPa. 6.4g of diisopropyl peroxydicarbonate solution was added to the reactor via a metering pump to initiate polymerization. Ethylene was continuously added to the reactor to maintain the pressure at 3.1MPa. After the reaction continued for 4 hours, the addition of ethylene was stopped and the temperature was lowered to terminate the reaction. The material in the reactor was placed in a centrifuge, dehydrated, washed several times with hot high-purity water, and vacuum-dried at 100-120° C. for 8 hours to obtain 1218 g of ethylene-chlorotrifluoroethylene resin.

[0070] Elemental analysis, F19 NMR and IR analysis confirmed that the mass percentage of chlorotrifluoroethylene structural units in the ethylene-chlorotrifluoroethylene resin was 50.8%, and the mass percentage of ethylene structural units was 49.2%.

[0071] Test Case

[0072] The modified ethylene-chlorotrifluoroethylene resins prepared in Examples 1 to 10 and the ethylene-chlorotrifluoroethylene resins prepared in Comparative Examples 1 to 2 were used to prepare coatings, and the hardness of the coatings was tested. The test results are shown in Table 1 below.

[0073] The preparation method of the coating film is as follows: place the sprayed steel plate in an oven to preheat at 290°C, take it out after the temperature reaches the predetermined temperature, and use a 30kV electrostatic spray gun to evenly spray powder resin on the sprayed steel plate until the unsprayed powder melts, and then place the sprayed steel plate in an oven at 280°C and bake it for 15 minutes. After the baking time is up, take it out and place it at room temperature to cool naturally.

[0074] Table 1 Hardness test results of ethylene-chlorotrifluoroethylene coating

[0075] Performance indicators <![CDATA[Hardness 1 ,HA]]> Example 1 80 Example 2 78 Example 3 77 Example 4 75 Example 5 78 Example 6 79 Example 7 81 Example 8 79 Example 9 78 Example 10 77 Comparative Example 1 68 Comparative Example 2 69

[0076] Note: Hardness 1 Test method: Tested in accordance with ASTM D2240 standard.

[0077] The experimental results show that compared with ethylene-chlorotrifluoroethylene resin, the hardness of ethylene-chlorotrifluoroethylene resin modified with silsesquioxane represented by structural formula (I) is greatly improved, and the scratch resistance is also greatly improved.

Claims

1. A silsesquioxane-modified ethylene-chlorotrifluoroethylene resin, characterized in that: The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin is prepared by copolymerizing monomers including a compound represented by structural formula (I), chlorotrifluoroethylene, and ethylene. The compound represented by structural formula (I) is as follows: Wherein: R is -O(CX2)nO(CH2)mOCH=CH2, X is independently selected from H, F, Cl or Br, n=an integer of 1 to 5, and m=an integer of 1 to 5.

2. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 1, characterized in that: In the compound represented by the structural formula (I), X is independently selected from H, F or Cl, n is an integer of 2 to 4, and m is an integer of 1 to 3.

3. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 2, wherein: In the compound represented by the structural formula (I), X is independently selected from H or F, n is an integer of 2 to 3, and m is an integer of 1 to 2.

4. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 1, wherein: The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin comprises 0.1 to 15 wt% of a compound structural unit represented by structural formula (I), 30 to 70 wt% of a chlorotrifluoroethylene structural unit and 30 to 70 wt% of an ethylene structural unit, wherein the total of the compound structural unit represented by structural formula (I), the chlorotrifluoroethylene structural unit and the ethylene structural unit is 100 wt%.

5. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 4, characterized in that: The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin comprises 0.1-12 wt% of a compound structural unit represented by structural formula (I), 40-60 wt% of a chlorotrifluoroethylene structural unit and 40-60 wt% of an ethylene structural unit, wherein the total of the compound structural unit represented by structural formula (I), the chlorotrifluoroethylene structural unit and the ethylene structural unit is 100 wt%.

6. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 1, characterized in that: The preparation method of the silsesquioxane-modified ethylene-chlorotrifluoroethylene resin comprises the following steps: (1) adding high-purity water, a dispersant, a pH buffer, a chain transfer agent, and a compound represented by structural formula (I) into a reactor, evacuating the reactor and replacing the reactor with nitrogen until the oxygen content in the reactor is less than 30 ppm; (2) The temperature inside the reactor is raised to 10-90°C; (3) adding chlorotrifluoroethylene, ethylene and initiator into the reactor; (4) The reaction is continued for 1.5 to 6 hours, and then the reaction is terminated. The product is washed and dried to obtain silsesquioxane-modified ethylene-chlorotrifluoroethylene resin.

7. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 6, characterized in that: The dispersant is selected from one or more of perfluorooctanoic acid ammonium salt or alkali metal salt, hexafluoropropylene oxide oligomer carboxylic acid ammonium salt and alkali metal salt, polyvinyl alcohol or hydroxypropyl methylcellulose.

8. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 6, characterized in that: The pH buffer is selected from one or more of sodium dihydrogen phosphate, potassium dihydrogen phosphate and sodium tetraborate.

9. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 6, characterized in that: The initiator is one or more selected from potassium persulfate, ammonium persulfate, sodium persulfate, potassium persulfate-sodium bisulfite, ammonium persulfate-sodium bisulfite and diisopropyl peroxydicarbonate.

10. The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to claim 6, characterized in that: The chain transfer agent is selected from one or more of carbon tetrachloride, ethyl acetate, ethylene glycol, diethyl malonate, isopentane and chloroform.

11. Use of the silsesquioxane-modified ethylene-chlorotrifluoroethylene resin according to any one of claims 1 to 10, characterized in that: The silsesquioxane-modified ethylene-chlorotrifluoroethylene resin is used as a coating for the inner lining of a chemical container or a self-supporting pipe.

Images