Calculating method for glass transition temperature of polyacrylate rubber and preparation method of polyacrylate rubber

Abstract

According to the method, on the basis of an FOX equation # imgabs0 #, glass transition temperature simulation values of part of monomers are obtained through a large amount of deduction and calculation, and then a corrected equation # imgabs1 # is obtained, it is verified that the simulation calculation value is quite close to a measured value, and it is verified that the simulation calculation value is close to the measured value; then designing a glass transition temperature by using the method to synthesize polyacrylate rubber; the synthesis method comprises the eight steps of raw material selection, raw material proportioning, emulsification, emulsion polymerization, demulsification and condensation, cleaning, drying and packaging. The composition proportion of the acrylate monomer can be designed according to the low-temperature requirement of the product, the glass transition temperature of the product is predicted by means of simulation calculation, the limitation that low-temperature data can only be obtained by actually measuring the product through an instrument at present is overcome, and the method plays an important role in research, development and production of domestic acrylate low-temperature rubber.

Description

Technical Field

[0001] The invention relates to the technical field of acrylic ester rubber production, in particular to a method for simulating the glass transition temperature of polyacrylate rubber and a preparation method thereof. Background Art

[0002] Acrylic rubber is a synthetic rubber made by copolymerization with acrylic ester as the main monomer. It has special properties such as high temperature resistance, oil resistance, ozone resistance and UV resistance. It is a heat-resistant and oil-resistant special rubber, mainly used as various heat-resistant and oil-resistant sealing rings, gaskets and oil seals for automobiles and locomotives.

[0003] In recent years, with the development of the times, the low-temperature requirements of rubber products from downstream industrial chains such as OEMs have become increasingly higher. Previously, the requirements could be met at around -20°C, but now many usage occasions require -30°C or even -40°C.

[0004] The glass transition temperature of a polymer, or Tg, is an important parameter for characterizing low-temperature performance. Formula to calculate (W X Indicates the mass fraction of this composition in the total monomers), but the prerequisite is that the Tg of each component needs to be known.

[0005] Commonly used monomers for acrylic rubber are: methyl acrylate, ethyl acrylate, butyl acrylate, n-octyl acrylate, isooctyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate and vulcanization point monomers.

[0006] Acrylic rubber has the characteristics of high temperature resistance and oil resistance. Low temperature acrylic rubber is especially inseparable from low temperature oil resistant monomers (such as methoxyethyl acrylate and ethoxyethyl acrylate), but the relevant Tg data of low temperature oil resistant monomers cannot be found. Vulcanization point monomers include: active chlorine type monomers, carboxyl type monomers, epoxy type monomers, double bond type monomers. Their usage is very small, but they play a vital role in the product's vulcanization speed, tensile strength, tensile elongation, permanent compression set and other properties. Similarly, the Tg of the product is almost impossible to find.

[0007] In addition, the Tg data of products are usually obtained through analytical instrument testing (such as DSC, DMA, etc.). On the one hand, instrument testing corresponds to the back-end, which is the data of product results and lacks data of early design and development; on the other hand, the cost and operation and maintenance costs of these equipment are relatively expensive, and generally companies will entrust third parties to conduct testing. Although entrusting testing saves costs, it takes a long time and is not conducive to the timely understanding of technical developers. Summary of the invention

[0008] The purpose of the present invention is to solve the above-mentioned problems. A method for simulating the glass transition temperature of polyacrylate rubber and a preparation method thereof are invented. The composition ratio of acrylate monomers can be designed according to the low-temperature requirements of the product, and the Tg of the product can be predicted based on simulation calculations. This breaks through the limitation that only actual measured products can be used to obtain low-temperature data, and helps the development and production of domestic low-temperature and ultra-low-temperature acrylate rubbers.

[0009] The specific technical solutions are as follows

[0010] by Based on this, through a large number of deductions and simulations, the simulated values ​​of the glass transition temperature of some monomers were obtained (not available in the manual), and then the corrected equation was obtained: This equation is then used to design Tg to synthesize polyacrylate rubber. The specific steps for synthesizing polyacrylate rubber are: raw material selection, raw material ratio, emulsification, emulsion polymerization, demulsification and coagulation, cleaning, drying, and packaging.

[0011] S1. The main monomers of the raw materials are selected as: one or more acrylates and modified monomers thereof, including methyl acrylate, ethyl acrylate, butyl acrylate, n-octyl acrylate, isooctyl acrylate, methoxyethyl acrylate, methoxymethyl acrylate, ethoxyethyl acrylate, and ethoxymethyl acrylate; the vulcanization point monomers are selected as: one or more of active chlorine type vulcanization point monomers, carboxyl type vulcanization point monomers, epoxy type vulcanization point monomers, and double bond type vulcanization point monomers;

[0012] S2. Selecting monomers from the monomers of S1 according to the required Tg and determining the composition ratio of each selected monomer;

[0013] S3. The emulsifier and the related water-soluble additive are added to the water, and then the monomer prepared in step S2 is added thereto to emulsify the raw material at an emulsification temperature of 30 to 45 ° C and an emulsification time of 30 to 60 minutes;

[0014] S4. Add an initiator to the emulsion obtained in step S3 to carry out emulsion polymerization, initiate the polymerization reaction at 15 to 45 ° C, the initiator is used in an amount of 0.05% to 0.5%, and then maintain the reaction temperature at 80 ± 10 ° C for polymerization for 1 to 4 hours to obtain an acrylate emulsion;

[0015] S5. After adding the terminator to the emulsion of S4, a 5% to 7% salt solution by mass is added to break the emulsion and coagulate at 55 to 85°C;

[0016] S6. Wash the demulsified rubber particles with water at a temperature of 55 to 85°C for 3 to 6 times;

[0017] S7. Place the cleaned rubber particles at a temperature of 80 to 120° C. for drying to obtain acrylic rubber, which is then packaged.

[0018] In some embodiments, in step S1, the active chlorine type curing site monomer is one or two of vinyl chloroacetate, 2-chloroethyl vinyl ether, vinyl chloroformate, and propylene chloroacetate.

[0019] In some embodiments, in step S1: the carboxyl type vulcanization site monomer is one or more of acrylic acid, maleic acid, maleic anhydride, monobutyl maleate, itaconic acid, monobutyl itaconate, monoethyl itaconate, fumaric acid, monobutyl fumarate, and monoethyl fumarate.

[0020] In some embodiments, in step S1: the epoxy type vulcanization site monomer is one or both of glycidyl methacrylate and allyl glycidyl ester.

[0021] In some embodiments, in step S1: the double bond type sulfurization site monomer is one or both of 3-methyl-2-butene ester and ethylidene norbornene.

[0022] In some embodiments, in step S3: the emulsifier is sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate or a compound thereof with a non-ionic compound, and the amount used is 1% to 5% of the total monomers.

[0023] In some embodiments, in step S4: the initiator is prepared from an organic peroxide oxidant and a reducing agent, wherein the organic peroxide oxidant is one or more of tert-butyl hydroperoxide, benzoyl peroxide, and isopropylbenzene hydroperoxide, the reducing agent is one or more of sodium bisulfite, ferrous sulfate, bleaching powder, and hydrosulfite, the amount of the initiator accounts for 0.1% to 0.3% of the total monomers, the oxidant: reducing agent = 1.05:1, and the molecular weight regulator is a thiol, and the mixing ratio is 0.01-1‰.

[0024] In some of the embodiments, in step S5: the terminator is one or more of sodium dimethyldithiocarbamate, N-isopropylhydroxylamine, sodium polysulfide, sodium nitrite, hydroquinone, tert-butylhydroquinone, and wood tar, and the amount used is 0.1% to 1.0% of the main monomer. The demulsification condition is: a sodium chloride / calcium chloride solution with a mass percentage of 5-8%, and the demulsification is carried out at 60 to 90°C.

[0025] In some of the embodiments, in steps S6 and S7: the obtained rubber material is washed with deionized water and a washing solution at a temperature of 60 to 80°C for 3 to 5 times, and then dehydrated and placed in an oven for drying at a temperature of 100 to 110°C to obtain a polyacrylate rubber with a specified glass transition temperature.

[0026] The present invention has the advantages

[0027] 1. The present invention proposes a method for simulating the glass transition temperature of polyacrylate rubber, which predicts the Tg of the product based on simulation calculations, and then designs the composition ratio of the acrylate monomer according to the low-temperature requirements of the product, thereby solving the limitation that only actual product measurements can be used to obtain low-temperature data.

[0028] 2. The present invention provides a set of mature preparation methods for polyacrylate rubber, optimizes the preparation process of polyacrylate rubber, and facilitates the development and production of domestic low-temperature and ultra-low-temperature acrylic rubber. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the technical implementation method of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in combination with the technical process steps, specific implementation conditions and materials in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the early stage, the glass transition temperature of the relevant raw materials was obtained through a large number of experimental deductions and verifications, and the values ​​will be explained in the examples (the values ​​of the vulcanization point monomers are obtained based on a large amount of data deduction, and are not entirely the glass transition temperature of the monomers themselves, and some are based on calculation results); when using the revised calculation formula, it will be set in the EXCEL table, and after entering the amount of each monomer, the simulated calculated value of Tg will be directly obtained.

[0031] Example 1

[0032] Design and development of heat-resistant active chlorine-type acrylic rubber with a Tg of about -18°C

[0033] According to simulation calculation: ethyl acrylate is selected as the main monomer, and vinyl chloroformate is the vulcanization point monomer, and the dosage is 2.5% of the main monomer; the polymerization process also includes sodium dodecyl sulfate as an emulsifier, and the dosage is 2.5% of the main monomer; mercaptan is used as a molecular weight regulator, and the mixing ratio is 1.5‰; emulsification at 30°C for 60 minutes; isopropyl hydroperoxide and insurance powder are used as initiators, and the dosage is 0.2%; the reaction is initiated at 35°C, and then kept warm at 85°C for 2.0 hours; 1.0% sodium dimethyldithiocarbamate is added; a 7.0% sodium chloride solution at 55°C is added for condensation and demulsification; it is washed with 55°C deionized water for 6 times and then dried in an oven at 110°C to obtain an active chlorine heat-resistant acrylic rubber.

[0034] In this example, the value of vinyl chloroformate is 1000, and the simulated value Tg calculated by the formula 模拟 The subsequent measured Tg 实测 The temperature is -17.21°C, the tensile strength of the acrylic rubber is 12MPa, the elongation at break is 280%, and the permanent compression set is 32%.

[0035] Example 2

[0036] Design and development of cold-resistant double-bond acrylic rubber with a Tg of about -28°C

[0037] According to simulation calculation: ethyl acrylate and butyl acrylate are selected as main monomers with a ratio of 7:3, and 3-methyl-2-butene ester is the vulcanization point monomer, and the amount is 2.5% of the main monomer; the polymerization process also includes sodium dodecyl sulfonate as an emulsifier, and the amount is 3.0% of the main monomer; mercaptan is used as a molecular weight regulator, and the ratio is 1.5‰; emulsification at 35°C for 30 minutes; isopropyl hydroperoxide and bleaching powder are used as initiators, and the amount is 0.15%; the reaction is initiated at 25°C, and then kept warm at 75°C for 4.0 hours; 1.0% N-isopropylhydroxylamine is added; a 60°C concentration of 6.0% sodium chloride solution is added for condensation and demulsification; it is washed with deionized water at 65°C for 4 times and then dried in an oven at 105°C to obtain a cold-resistant double-bond acrylic rubber.

[0038] In this example, the value of 3-methyl-2-butenyl ester is 800, and the simulated value Tg calculated by the formula 模拟 The subsequent measured Tg 实测 The temperature is -28.15°C, the tensile strength of the acrylic rubber is 11 MPa, the elongation at break is 220%, and the permanent compression set is 28.4%.

[0039] Example 3

[0040] Design and development of ultra-cold-resistant epoxy acrylate rubber with a Tg of about -35°C

[0041] According to simulation calculation: ethyl acrylate, butyl acrylate, and methoxyethyl acrylate are selected as main monomers, with a ratio of 5:4:1; the vulcanization point monomer is glycidyl methacrylate, and the amount used is 1.5% of the main monomer; the polymerization process also includes using sodium dodecylbenzene sulfonate as an emulsifier, with an amount of 4.0% of the main monomer; using thiol as a molecular weight regulator, with a ratio of 1.0‰; emulsification at 35°C for 45 minutes; using tert-butyl hydroperoxide and sodium bisulfite as initiators, with an amount of 0.1%; initiating the reaction at 30°C, and keeping warm at 80°C for 3.0 hours; adding 1.0% tert-butylhydroquinone; adding a 70°C concentration of 6.0% calcium chloride solution for coagulation and demulsification; washing with 70°C deionized water for 4 times and then drying in a 105°C oven to obtain an ultra-cold-resistant epoxy acrylate rubber.

[0042] In this example, the value of glycidyl methacrylate is 75, the value of methoxyethyl acrylate is -40, and the simulated value Tg calculated by the formula 模拟 The subsequent measured Tg 实测 The temperature is -34.26°C, the tensile strength of acrylic rubber is 10 MPa, the elongation at break is 200%, and the permanent compression set is 35%.

[0043] Example 4

[0044] Design and development of extremely cold-resistant carboxyl-type acrylic rubber with a Tg of about -42°C

[0045] According to simulation calculations: ethyl acrylate, butyl acrylate, and methoxyethyl acrylate were selected as the main monomers, with a ratio of 1:6:3; the vulcanization point monomer was monobutyl maleate, with an amount of 1.5% of the main monomer; the polymerization process also included sodium dodecyl sulfate and a non-ionic composite emulsifier (ratio of 5:1), with an amount of 6.0% of the main monomer; mercaptan was used as a molecular weight regulator, with a ratio of 1.0‰; emulsification at 35°C for 60 minutes; isopropyl hydroperoxide and persulfate were used. The ammonium hydroxide compound is used as an oxidant (4:1), and the insurance powder is used as a reducing agent, and the dosage is 0.1% of the total monomers; the reaction is initiated at 35°C and kept warm at 75°C for 3.0 hours; sodium dimethyldithiocarbamate and hydroquinone (ratio is 1:1) are added, and the dosage accounts for 2.0% of the total monomers; a 7.0% calcium chloride solution at 65°C is added for coagulation and demulsification; it is washed with deionized water at 75°C for 4 times and then dried in an oven at 100°C to obtain an extremely cold-resistant carboxyl type acrylate rubber.

[0046] In this example, the value of monobutyl maleate is 10, and the simulated value Tg calculated by the formula 模拟 The subsequent measured Tg 实测 The temperature is -43.34℃, the tensile strength of acrylic rubber is 9MPa, the elongation at break is 150%, and the permanent compression deformation is 25%.

[0047] From the formula It can be seen that the simulated value Tg is closely related to the vulcanization point monomer. When the amount of the vulcanization point monomer increases, the simulated value Tg increases; conversely, the simulated value Tg decreases. When the amount of the vulcanization point monomer remains unchanged, the ratio of each component monomer can also be adjusted to adjust the size of the simulated value Tg (and the oil resistance also changes accordingly).

[0048] It can be seen from the examples that the errors between the measured values ​​and the design required values ​​are generally within 2°C, and most are within 1°C, indicating that the accuracy of the simulation calculation is relatively high.

[0049] In addition, the error between the simulated value calculated using the formula and the actual measured value is very small, so it can be used as an effective means of indirect characterization of Tg without instrument testing when developing products.

[0050] Technical personnel should note that although the present invention has been described according to the above specific implementation methods, the inventive concept of the present invention is not limited to this invention, and any modification using the inventive concept will be included in the scope of protection of this patent.

Claims

1. A method for calculating the glass transition temperature of polyacrylate rubber and a method for preparing the same, characterized in that: Tg can be designed and polyacrylate rubber can be synthesized according to requirements: The simulation method is based on the FOX equation Based on this, through a large number of deductions and simulations, the simulated values ​​of the glass transition temperature of some monomers were obtained, and then the corrected equation was obtained: According to this equation, the glass transition temperature is designed to synthesize polyacrylate rubber. The preparation method of polyacrylate rubber includes the following steps: raw material selection, raw material ratio, emulsification, emulsion polymerization, demulsification and coagulation, cleaning, drying, and packaging. The specific process is as follows: S1. The main monomers of the raw materials are selected as: one or more acrylates and modified monomers thereof, including methyl acrylate, ethyl acrylate, butyl acrylate, n-octyl acrylate, isooctyl acrylate, methoxyethyl acrylate, methoxymethyl acrylate, ethoxyethyl acrylate, and ethoxymethyl acrylate; the vulcanization point monomers are selected as: one or more of active chlorine type vulcanization point monomers, carboxyl type vulcanization point monomers, epoxy type vulcanization point monomers, and double bond type vulcanization point monomers; S2. In the monomers of S1, a monomer is selected according to the required glass transition temperature, and a composition ratio of each selected monomer is determined; S3. The emulsifier and the related water-soluble additive are added to the water, and then the monomer prepared in step S2 is added thereto to emulsify the raw material at an emulsification temperature of 30 to 45 ° C and an emulsification time of 30 to 60 minutes; S4. Add an initiator to the emulsion obtained in step S3 to carry out emulsion polymerization, initiate the polymerization reaction at 15 to 45 ° C, the initiator is used in an amount of 0.05% to 0.5%, and then maintain the reaction temperature at 80 ± 10 ° C for polymerization for 1 to 4 hours to obtain an acrylate emulsion; S5. After adding the terminator to the emulsion of S4, a 5% to 7% salt solution by mass is added to break the emulsion and coagulate at 55 to 85°C; S6. Wash the demulsified rubber particles with water at a temperature of 55 to 85°C for 3 to 6 times; S7. Place the cleaned rubber particles at a temperature of 80 to 120° C. for drying to obtain acrylic rubber, which is then packaged.

2. The method for simulating the glass transition temperature of polyacrylate rubber and the preparation method thereof according to claim 1, characterized in that: In the step S1, the active chlorine type vulcanization site monomer is one or two of vinyl chloroacetate, 2-chloroethyl vinyl ether, vinyl chloroformate, and propylene chloroacetate.

3. The method for simulating the glass transition temperature of polyacrylate rubber and the preparation method thereof according to claim 1, characterized in that: In step S1, the carboxyl type vulcanization site monomer is one or more of acrylic acid, maleic acid, maleic anhydride, monobutyl maleate, itaconic acid, monobutyl itaconate, monoethyl itaconate, fumaric acid, monobutyl fumarate, and monoethyl fumarate.

4. The method for calculating the glass transition temperature of polyacrylate rubber and the preparation method thereof according to claim 1, characterized in that: In the step S1, the epoxy type vulcanization site monomer is one or both of glycidyl methacrylate and allyl glycidyl ester.

5. The method for simulating the glass transition temperature of polyacrylate rubber and the preparation method thereof according to claim 1, characterized in that: In the step S1, the double bond type sulfurization site monomer is one or two of 3-methyl-2-butene ester and ethylidene norbornene.

6. The method for simulating the glass transition temperature of polyacrylate rubber and the preparation method thereof according to claim 1, characterized in that: In the step S3, the emulsifier is prepared from sodium dodecyl sulfate, sodium dodecyl sulfonate and sodium dodecylbenzene sulfonate or compounded with non-ionic, and the amount used is 1% to 5% of the total monomers.

7. The method for simulating the glass transition temperature of polyacrylate rubber and the preparation method thereof according to claim 1, characterized in that: In the step S4: the initiator is prepared from an organic peroxide oxidant and a reducing agent, wherein the organic peroxide oxidant is one or more of tert-butyl hydroperoxide, benzoyl peroxide, and cumene hydroperoxide, the reducing agent is one or more of sodium bisulfite, ferrous sulfate, bleaching powder, and hydrosulfite, the amount of the initiator accounts for 0.1% to 0.3% of the total monomers, the oxidant: reducing agent = 1.05:1, and the molecular weight regulator is mercaptan, and the mixing ratio is 0.01-1‰.

8. The method for simulating the glass transition temperature of polyacrylate rubber and the preparation method thereof according to claim 1, characterized in that: In the step S5, the terminator is one or more of sodium dimethyldithiocarbamate, N-isopropylhydroxylamine, sodium polysulfide, sodium nitrite, hydroquinone, tert-butylhydroquinone, and wood tar, and the amount used is 0.1% to 1.0% of the main monomer. The demulsification condition is: sodium chloride / calcium chloride solution with a mass percentage of 5-8% is used to demulsify at 60 to 90°C.

9. The method for simulating the glass transition temperature of polyacrylate rubber and the preparation method thereof according to claim 1, characterized in that: In the steps S6 and S7, the obtained rubber material is washed with deionized water and a washing solution at a temperature of 60 to 80° C. for 3 to 5 times, and then dehydrated and placed in an oven for drying at a temperature of 100 to 110° C. to obtain a polyacrylate rubber with a specified glass transition temperature.

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