Improved food additive styrene butadiene rubber and preparation method thereof

Abstract

The invention relates to the field of food additives, in particular to an improved food additive butadiene styrene rubber and a preparation method thereof. The preparation method is characterized in that the solid structure regulator is added into the raw materials, so that the adding proportion of the polar additive is reduced, the block proportion in the rubber is obviously reduced (less than 5%), and the added solid structure regulator enhances the activation effect and promotes the speed of butadiene and styrene to be more uniform during polymerization reaction; according to the present invention, the rubber molecules are effectively linked so as to form the randomness of more than 95%, such that the elasticity and the tensile strength of the finished product rubber are substantially improved, and the requirements of customers on the quality and the use performance of the food rubber can be met.

Description

Technical Field

[0001] The invention relates to the field of food additives, in particular to an improved food additive styrene-butadiene rubber and a preparation method thereof, which is particularly suitable for the manufacture of gum bases such as chewing gum, bubble gum and the like, and is also suitable for medical and sanitary products, food packaging materials, children's toys and the like. Background Art

[0002] As we all know, in the field of food additives, food rubber is an important additive material. It not only has to meet the requirements of high purity, being non-toxic, odorless and free of impurities, but also has to have certain elasticity and tensile strength.

[0003] Chinese invention patent ZL03140520.7 discloses a method for manufacturing food-grade butadiene or butadiene and styrene solution rubber, which is prepared by using C4-C8 mixed saturated aliphatic hydrocarbons as solvents, organic substances composed of carbon, hydrogen, oxygen and other elements that can be fully polymerized into the rubber polymer chain as cross-linking coupling agents, food-grade BHT as an antioxidant, and polymerizing butadiene and styrene or butadiene at relatively high monomer concentrations and polymerization temperatures. The food rubber prepared by this method is non-toxic and tasteless, and can be widely used in chewing gum, bubble gum, medical and health care, food packaging, food production machinery and other products.

[0004] However, the amount of polar additives added to the solvent oil in this method is 3000ppm-3200ppm, which can easily form 25%-30% blocks in the colloid, affecting the elasticity and tensile strength of food rubber, making its quality and performance unable to meet the needs of users. At the same time, in this method, butadiene and styrene are added to the polymerization kettle at the same time. Since the reaction rates of butadiene and styrene are not the same, the block ratio of styrene in the rubber product is as high as 30%, and the randomness is only 70%. The polymerization reaction time of only 15 minutes also makes it impossible to complete the microstructure. In addition, since this method does not control the temperature during the polymerization reaction, this will cause uneven molecular weight distribution, and a large amount of gel will be produced in the colloid, further affecting the elasticity and tensile strength of the colloid. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies of the prior art and to provide an improved food additive styrene-butadiene rubber and a preparation method thereof. The food rubber prepared by the method has a randomness of more than 95%, a block ratio of less than 5%, and a greatly reduced gel content in the colloid, so that the rubber has better elasticity and tensile strength, and can meet the customer's requirements for the quality and performance of the food rubber.

[0006] To solve the above problems, the following technical solutions are adopted: The improved food additive styrene-butadiene rubber of the present invention is characterized by comprising the following raw materials in parts by weight: 500-750 parts of butadiene, 250-500 parts of styrene, 2-10 parts of organic lithium initiator, 2-15 parts of polar additive, 1-10 parts of solid structure regulator, 2-10 parts of coupling agent, 1-5 parts of antioxidant, 3000-11250 parts of solvent oil.

[0007] Wherein, the organic lithium initiator is n-butyl lithium, tert-butyl lithium, isobutyl lithium, sec-butyl lithium or dilithium. The polar additive is tetrahydrofuran, ethylene glycol dimethyl ether or diethylene glycol dimethyl ether. The solid structure regulator is sodium dodecylbenzene sulfonate or tetrasodium ethylenediaminetetraacetic acid. The coupling agent is silicon tetrachloride, divinylbenzene or diethyl adipate. The antioxidant is 2,6-di-tert-butyl-p-cresol or 2,6-di-tert-butyl-4-methylphenol. The solvent oil is cyclohexane, hexane or C4-C8 mixed saturated aliphatic hydrocarbon solvent.

[0008] Furthermore, the raw materials also include 1 to 10 parts of deionized water.

[0009] The preparation method of the improved food additive styrene-butadiene rubber of the present invention is characterized in that it comprises the following steps: In the first step, 3000-11250 parts of solvent oil and 1-10 parts of solid structure regulator are added into a polymerization kettle to fully dissolve the solid structure regulator.

[0010] In the second step, 2 to 15 parts of polar additives are added into the polymerization kettle and stirred for 3 to 10 minutes to evenly mix the polar additives with the solvent oil.

[0011] The third step is to put 2-10 parts of organic lithium initiator, 500-750 parts of butadiene and 250-500 parts of styrene into a polymerization kettle and stir evenly.

[0012] Step 4: After the addition is completed, the temperature of the polymerization kettle is controlled at 95-110 degrees and the pressure is controlled at 3-6 MPa for 20-80 minutes to allow the materials in the polymerization kettle to be fully polymerized. Then add 2-10 parts of coupling agent and continue to react for 5-30 minutes. Then add 0.1-1 parts of antioxidant and continue to react for 5-20 minutes before discharging the materials from the polymerization kettle.

[0013] The fifth step is to pump the discharging rubber liquid from the polymerization kettle into the flash tank and keep it in the flash tank for 20 to 30 minutes, so that a large amount of solvent oil therein can be evaporated by flash evaporation to achieve the purpose of recovering a large amount of high-purity solvent oil.

[0014] The sixth step is to pump the glue liquid in the flash tank into the blending tank. A static mixer is installed on the connecting pipe between the flash tank and the blending tank. When the glue liquid is in a normal conveying state, the remaining part of 1 to 5 parts of the antioxidant is uniformly injected into the static mixer through a metering pump to make it evenly mixed with the glue liquid. After that, the glue liquid is stirred in the blending tank for 1 to 3 hours.

[0015] The seventh step is to input the rubber liquid in the mixing tank into the condensation kettle through a pump, and evaporate the solvent oil in the rubber liquid in the condensation kettle into the oil-water separation tank through steam, so that only rubber and water are left in the condensation kettle, which is called rubber particle water.

[0016] In the eighth step, the rubber particle water from the coagulation kettle is pumped into the post-processing device for washing, dehydration, expansion and drying to remove the water and residues therein and obtain pure rubber particles.

[0017] The ninth step is to carry out briquetting, metal inspection, weighing and packaging on the rubber particles treated by the post-processing device, so as to obtain the improved food additive styrene-butadiene rubber product.

[0018] Furthermore, in the first step, all the solvent oil is first heated to 75-85 degrees, and then 20% of it is added to the polymerization kettle. Then 1-10 parts of the solid structure regulator are added to the polymerization kettle to fully dissolve it in the 20% solvent oil. Finally, the remaining 80% of the solvent oil is all added to the polymerization kettle.

[0019] In the third step, 2 to 10 parts of an organic lithium initiator are first added to a polymerization kettle and stirred for 3 to 5 minutes to make it uniformly mixed. At the same time, 10 to 90% of 500 to 750 parts of butadiene are uniformly mixed with 250 to 500 parts of styrene. After the organic lithium initiator is added, the mixture of butadiene and styrene is uniformly input into the polymerization kettle for 20 to 90 minutes, and the temperature of the polymerization kettle is controlled at 95 to 110 degrees. After the input is completed, the remaining butadiene is uniformly input into the polymerization kettle for 5 to 40 minutes.

[0020] In the fourth step, when the polymerization reactor is discharged, 1 to 10 parts of deionized water are added to the discharge pipeline to terminate the polymerization reaction of the material.

[0021] In the above preparation method, in the first step, before the solvent oil is fed into the polymerization reactor, it is first purified to a polymerization grade of 10ppm-15ppm using a solvent oil refining tower.

[0022] In the third step, before the butadiene is put into the polymerization kettle, it is first purified by using a butadiene refining tower to make its purity reach 99.9% polymerization grade. Before the styrene is put into the polymerization kettle, it is first purified by using a molecular sieve refining bed to make its purity reach 99.8% raw material polymerization grade.

[0023] The capacity of the polymerization kettle should meet the following requirements: after all the solvent oil, butadiene and styrene are put into the polymerization kettle, the capacity of the solvent oil and the materials in the polymerization kettle accounts for 70-80%.

[0024] The post-processing device of the eighth step includes a rubber washing tank, a vibrating dehydration screen, an extrusion dehydrator, a screw high-temperature and high-pressure expander and a vibrating fluidized bed. The rubber water from the condensation kettle is first washed with a rubber washing tank, and the temperature of the rubber washing tank is maintained at above 80 degrees. Then, the rubber water is passed through a vibrating dehydration screen to remove a large amount of water, and the remaining rubber particles containing a small amount of water are sent to the extrusion dehydrator to remove the remaining water and squeeze into rubber blocks the size of fingernails. After that, the rubber blocks are sent to the screw high-temperature and high-pressure expander, the pressure of the screw high-temperature and high-pressure expander is controlled at 35~50 MPa, and the die temperature is controlled at 150~170 degrees, so that the rubber blocks are extruded and expanded into rubber particles while all the residues therein are volatilized. Finally, the material treated by the screw high-temperature and high-pressure expander is transported to the vibrating fluidized bed, the temperature of the vibrating fluidized bed is controlled at 60~80 degrees, and the volatilized residues are taken away by hot air, thereby obtaining pure rubber particles.

[0025] The above solution has the following advantages: The improved food additive styrene-butadiene rubber and its preparation method of the present invention add a solid structure regulator to the solvent oil, thereby reducing the addition ratio of polar additives, making the block ratio in the rubber significantly reduced (less than 5%), and the added solid structure regulator enhances the activation effect, promotes the polymerization rate of butadiene and styrene to be more uniform, makes the rubber molecules effectively linked, forms more than 95% of the randomness, and greatly improves the elasticity and tensile strength of the finished rubber. At the same time, the extension of the polymerization reaction time makes the microstructure in the rubber more stable, the molecular weight and the molecular structure can be fully and perfectly combined, greatly reduces the gel content in the colloid, and further improves the elasticity and tensile strength of the finished rubber, which can meet the user's requirements for the quality and performance of food rubber.

[0026] Further, in the preparation method of the improved food additive styrene-butadiene rubber of the present invention, butadiene and styrene are not directly put into the operating method of the polymerization kettle by the prior art, but first an organic lithium initiator is put into the polymerization kettle, and stirred evenly, 10-90% of butadiene and all styrenes are pre-mixed evenly at the same time, and the speed of the mixture input into the polymerization kettle is controlled, and finally the remaining butadiene is input into the polymerization kettle. This operating method can make butadiene and styrene fully premixed before carrying out polymerization reaction, and the uniform speed input of the mixture can make the butadiene and styrene entering the polymerization kettle fully polymerize, and the butadiene added at last can polymerize again with the unreacted styrene. This new process can make the polymerization reaction of butadiene and styrene more complete, and compared with a large amount of gel produced due to the uneven mixing of butadiene and styrene when directly put into the polymerization kettle, the gel content in its colloid is greatly reduced. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the embodiments. Embodiment 1

[0028] The improved food additive styrene-butadiene rubber of the present embodiment comprises the following raw materials in parts by weight: 500 parts of butadiene, 500 parts of styrene, 4 parts of organic lithium initiator, 5 parts of polar additive, 3 parts of solid structure regulator, 5 parts of coupling agent, 2 parts of antioxidant, 5000 parts of solvent oil, and 4 parts of deionized water.

[0029] The organic lithium initiator is n-butyl lithium. The polar additive is tetrahydrofuran. The solid structure regulator is sodium dodecylbenzene sulfonate. The coupling agent is silicon tetrachloride. The antioxidant is 2,6-di-tert-butyl-p-cresol. The solvent oil is cyclohexane solvent.

[0030] The preparation method comprises the following steps: In the first step, 5000 parts of solvent oil cyclohexane solvent and 3 parts of solid structure regulator sodium dodecylbenzene sulfonate are put into the polymerization kettle to fully dissolve the sodium dodecylbenzene sulfonate. The operation method is: first heat all the cyclohexane solvent to 80 degrees, and then put 20% of it into the polymerization kettle; then put 3 parts of sodium dodecylbenzene sulfonate into the polymerization kettle to fully dissolve it in the 20% cyclohexane solvent; finally, put the remaining 80% of the cyclohexane solvent into the polymerization kettle.

[0031] The cyclohexane solvent is first purified to a polymerization grade of 10ppm-15ppm using a solvent oil refining tower before being fed into the polymerization kettle.

[0032] In the second step, 5 parts of tetrahydrofuran, a polar additive, are added into the polymerization kettle and stirred for 5 minutes to uniformly mix the tetrahydrofuran and the cyclohexane solvent.

[0033] The third step is to put 4 parts of organic lithium initiator n-butyl lithium, 500 parts of butadiene and 500 parts of styrene into the polymerization kettle and stir them evenly. The operation method is: first put 4 parts of n-butyl lithium into the polymerization kettle, stir for 4 minutes to make it evenly mixed; at the same time, 20% of 500 parts of butadiene are evenly mixed with 500 parts of styrene. After the n-butyl lithium is put in, the mixture of butadiene and styrene is evenly put into the polymerization kettle for 40 minutes, and the temperature of the polymerization kettle is controlled at 100 degrees. After the input is completed, the remaining butadiene is evenly put into the polymerization kettle for 30 minutes.

[0034] Before putting butadiene into the polymerization kettle, it is first purified by using a butadiene refining tower to make its purity reach 99.9% polymerization grade. Before putting styrene into the polymerization kettle, it is first purified by using a molecular sieve refining bed to make its purity reach 99.8% raw material polymerization grade. The capacity of the polymerization kettle should meet the following requirements: after all cyclohexane solvent, butadiene and styrene are put into the polymerization kettle, the capacity of cyclohexane solvent, butadiene and styrene in the polymerization kettle accounts for 70-80%.

[0035] Step 4: After the addition is completed, the temperature of the polymerization kettle is controlled at 100 degrees and the pressure is controlled at 4 MPa for 40 minutes to allow the materials in the polymerization kettle to be fully polymerized. Then add 5 parts of coupling agent silicon tetrachloride and continue the reaction for 10 minutes. Then add 0.2 parts of antioxidant 2,6-di-tert-butyl-p-cresol and continue the reaction for 10 minutes before discharging the materials from the polymerization kettle. When discharging the materials from the polymerization kettle, add 4 parts of deionized water to the discharge pipeline to terminate the polymerization reaction of the materials.

[0036] The fifth step is to pump the discharging glue liquid from the polymerization kettle into a flash tank and keep it in the flash tank for 24 minutes, so that a large amount of cyclohexane solvent therein is evaporated by flash evaporation to achieve the purpose of recovering a large amount of high-purity solvent oil.

[0037] In the sixth step, the glue liquid in the flash tank is pumped into the blending tank. A static mixer is installed on the connecting pipe between the flash tank and the blending tank. When the glue liquid is in a normal conveying state, the remaining 1.8 parts of the antioxidant 2,6-di-tert-butyl-p-cresol are uniformly injected into the static mixer through a metering pump to make it uniformly mixed with the glue liquid. After that, the glue liquid is stirred in the blending tank for 1.5 hours.

[0038] The seventh step is to input the rubber liquid in the mixing tank into the coagulation kettle through a pump, and evaporate the cyclohexane solvent in the rubber liquid in the coagulation kettle into the oil-water separation tank through steam, so that only rubber and water are left in the coagulation kettle, which is called rubber particle water.

[0039] In the eighth step, the rubber particle water from the coagulation kettle is pumped into the post-processing device for washing, dehydration, expansion and drying to remove the water and residues therein and obtain pure rubber particles.

[0040] The post-processing device includes a rubber washing tank, a vibrating dehydration screen, an extrusion dehydrator, a screw high-temperature and high-pressure expander and a vibrating fluidized bed. The rubber water from the coagulation kettle is first washed with a rubber washing tank, and the temperature of the rubber washing tank is maintained above 80 degrees. Then, the rubber water is passed through a vibrating dehydration screen to remove a large amount of water, and the remaining rubber particles containing a small amount of water are sent to the extrusion dehydrator to remove the remaining water and squeeze into rubber blocks the size of a fingernail. After that, the rubber blocks are sent to the screw high-temperature and high-pressure expander. The pressure of the screw high-temperature and high-pressure expander is controlled at 40 MPa, and the die temperature is controlled at 160 degrees, so that the rubber blocks are extruded and expanded into rubber particles while all the residues therein are volatilized. Finally, the material treated by the screw high-temperature and high-pressure expander is transported to the vibrating fluidized bed. The temperature of the vibrating fluidized bed is controlled at 70 degrees, and the volatilized residues are taken away by hot air, thereby obtaining pure rubber particles.

[0041] The ninth step is to carry out briquetting, metal inspection, weighing and packaging on the rubber particles treated by the post-processing device, so as to obtain the improved food additive styrene-butadiene rubber product. Embodiment 2

[0042] The improved food additive styrene-butadiene rubber of the present embodiment comprises the following raw materials in parts by weight: 750 parts of butadiene, 250 parts of styrene, 6 parts of organic lithium initiator, 10 parts of polar additive, 8 parts of solid structure regulator, 8 parts of coupling agent, 4 parts of antioxidant, 9000 parts of solvent oil, and 7 parts of deionized water.

[0043] The organic lithium initiator is isobutyl lithium. The polar additive is tetrahydrofuran. The solid structure regulator is sodium dodecylbenzene sulfonate. The coupling agent is silicon tetrachloride. The antioxidant is 2,6-di-tert-butyl-p-cresol. The solvent oil is cyclohexane solvent.

[0044] The preparation method comprises the following steps: In the first step, 9000 parts of solvent oil cyclohexane solvent and 8 parts of solid structure regulator sodium dodecylbenzene sulfonate are put into the polymerization kettle to fully dissolve the sodium dodecylbenzene sulfonate. The operation method is: first heat all the cyclohexane solvent to 80 degrees, and then put 20% of it into the polymerization kettle; then put 8 parts of sodium dodecylbenzene sulfonate into the polymerization kettle to fully dissolve it in the 20% cyclohexane solvent; finally, put the remaining 80% of the cyclohexane solvent into the polymerization kettle.

[0045] The cyclohexane solvent is first purified to a polymerization grade of 10ppm-15ppm using a solvent oil refining tower before being fed into the polymerization kettle.

[0046] In the second step, 10 parts of tetrahydrofuran, a polar additive, are added into the polymerization kettle and stirred for 8 minutes to uniformly mix the tetrahydrofuran and the cyclohexane solvent.

[0047] The third step is to put 6 parts of isobutyl lithium, an organic lithium initiator, 750 parts of butadiene and 250 parts of styrene into the polymerization kettle and stir them evenly. The operation method is as follows: first put 6 parts of isobutyl lithium into the polymerization kettle and stir for 4 minutes to make it evenly mixed; at the same time, evenly mix 50% of the 750 parts of butadiene with 250 parts of styrene. After the isobutyl lithium is put in, the mixture of butadiene and styrene is evenly put into the polymerization kettle for 60 minutes. At this time, the temperature of the polymerization kettle is controlled at 105 degrees. After the input is completed, the remaining butadiene is evenly put into the polymerization kettle for 15 minutes.

[0048] Before putting butadiene into the polymerization kettle, it is first purified by using a butadiene refining tower to make its purity reach 99.9% polymerization grade. Before putting styrene into the polymerization kettle, it is first purified by using a molecular sieve refining bed to make its purity reach 99.8% raw material polymerization grade. The capacity of the polymerization kettle should meet the following requirements: after all cyclohexane solvent, butadiene and styrene are put into the polymerization kettle, the capacity of cyclohexane solvent, butadiene and styrene in the polymerization kettle accounts for 70-80%.

[0049] Step 4: After the addition is completed, the temperature of the polymerization kettle is controlled at 105 degrees and the pressure is controlled at 5 MPa for 60 minutes to allow the materials in the polymerization kettle to be fully polymerized. Then add 8 parts of coupling agent silicon tetrachloride and continue to react for 20 minutes. Then add 0.5 parts of antioxidant 2,6-di-tert-butyl-p-cresol and continue to react for 15 minutes before discharging the materials from the polymerization kettle. When discharging the materials from the polymerization kettle, add 7 parts of deionized water to the discharge pipeline to terminate the polymerization reaction of the materials.

[0050] The fifth step is to pump the discharging glue liquid from the polymerization kettle into a flash tank and keep it in the flash tank for 26 minutes, so that a large amount of cyclohexane solvent therein is evaporated by flash evaporation to achieve the purpose of recovering a large amount of high-purity solvent oil.

[0051] In the sixth step, the glue liquid in the flash tank is pumped into the blending tank. A static mixer is installed on the connecting pipe between the flash tank and the blending tank. When the glue liquid is in a normal conveying state, the remaining 3.5 parts of the antioxidant 2,6-di-tert-butyl-p-cresol are uniformly injected into the static mixer through a metering pump to make it uniformly mixed with the glue liquid. After that, the glue liquid is stirred in the blending tank for 2 hours.

[0052] The seventh step is to input the rubber liquid in the mixing tank into the coagulation kettle through a pump, and evaporate the cyclohexane solvent in the rubber liquid in the coagulation kettle into the oil-water separation tank through steam, so that only rubber and water are left in the coagulation kettle, which is called rubber particle water.

[0053] In the eighth step, the rubber particle water from the coagulation kettle is pumped into the post-processing device for washing, dehydration, expansion and drying to remove the water and residues therein and obtain pure rubber particles.

[0054] The post-processing device includes a rubber washing tank, a vibrating dehydration screen, an extrusion dehydrator, a screw high-temperature and high-pressure expander and a vibrating fluidized bed. The rubber water from the coagulation kettle is first washed with a rubber washing tank, and the temperature of the rubber washing tank is maintained above 80 degrees. Then, the rubber water is passed through a vibrating dehydration screen to remove a large amount of water, and the remaining rubber particles containing a small amount of water are sent to the extrusion dehydrator to remove the remaining water and squeeze into rubber blocks the size of a fingernail. After that, the rubber blocks are sent to the screw high-temperature and high-pressure expander. The pressure of the screw high-temperature and high-pressure expander is controlled at 45 MPa, and the die temperature is controlled at 165 degrees, so that the rubber blocks are extruded and expanded into rubber particles while all the residues therein are volatilized. Finally, the material treated by the screw high-temperature and high-pressure expander is transported to the vibrating fluidized bed. The temperature of the vibrating fluidized bed is controlled at 75 degrees, and the volatilized residues are taken away by hot air, thereby obtaining pure rubber particles.

[0055] The ninth step is to carry out briquetting, metal inspection, weighing and packaging on the rubber particles treated by the post-processing device, so as to obtain the improved food additive styrene-butadiene rubber product. Embodiment 3

[0056] The improved food additive styrene-butadiene rubber of the present embodiment comprises the following raw materials in parts by weight: 550 parts of butadiene, 450 parts of styrene, 10 parts of organic lithium initiator, 15 parts of polar additive, 10 parts of solid structure regulator, 10 parts of coupling agent, 5 parts of antioxidant, 11250 parts of solvent oil, and 10 parts of deionized water.

[0057] Wherein, the organic lithium initiator is sec-butyl lithium. The polar additive is diethylene glycol dimethyl ether. The solid structure regulator is ethylenediaminetetraacetic acid tetrasodium salt. The coupling agent is diethyl adipate. The antioxidant is 2,6-di-tert-butyl-4-methylphenol. The solvent oil is a C4-C8 mixed saturated aliphatic hydrocarbon solvent.

[0058] The preparation method comprises the following steps: In the first step, 11250 parts of solvent oil C4-C8 mixed saturated aliphatic hydrocarbon solvent and 10 parts of solid structure regulator ethylenediaminetetraacetic acid tetrasodium salt are put into the polymerization kettle to fully dissolve the ethylenediaminetetraacetic acid tetrasodium salt. The operation method is as follows: firstly heat all the C4-C8 mixed saturated aliphatic hydrocarbon solvent to 85 degrees, and then put 20% of it into the polymerization kettle; then put 10 parts of ethylenediaminetetraacetic acid tetrasodium salt into the polymerization kettle to fully dissolve it in 20% of the C4-C8 mixed saturated aliphatic hydrocarbon solvent; finally, put the remaining 80% of the C4-C8 mixed saturated aliphatic hydrocarbon solvent into the polymerization kettle.

[0059] The C4-C8 mixed saturated aliphatic hydrocarbon solvent is first purified to a polymerization grade of 10ppm-15ppm using a solvent oil refining tower before being fed into the polymerization kettle.

[0060] In the second step, 15 parts of polar additive diethylene glycol dimethyl ether are added into the polymerization kettle and stirred for 10 minutes to uniformly mix the diethylene glycol dimethyl ether and the C4-C8 mixed saturated aliphatic hydrocarbon solvent.

[0061] The third step is to put 10 parts of organic lithium initiator sec-butyl lithium, 550 parts of butadiene and 450 parts of styrene into the polymerization kettle and stir them evenly. The operation method is: first put 10 parts of sec-butyl lithium into the polymerization kettle and stir for 5 minutes to make it evenly mixed; at the same time, 90% of 550 parts of butadiene are evenly mixed with 450 parts of styrene. After the sec-butyl lithium is put in, the mixture of butadiene and styrene is evenly put into the polymerization kettle for 90 minutes. At this time, the temperature of the polymerization kettle is controlled at 110 degrees. After the input is completed, the remaining butadiene is evenly put into the polymerization kettle for 5 minutes.

[0062] Before putting butadiene into the polymerization kettle, it is first purified by using a butadiene refining tower to make it reach a polymerization grade of 99.9%. Before putting styrene into the polymerization kettle, it is first purified by using a molecular sieve refining bed to make it reach a raw material polymerization grade of 99.8%. The capacity of the polymerization kettle should meet the following requirements: after all C4-C8 mixed saturated aliphatic hydrocarbon solvents, butadiene and styrene are put into the polymerization kettle, the capacity of C4-C8 mixed saturated aliphatic hydrocarbon solvents, butadiene and styrene in the polymerization kettle accounts for 70-80%. .

[0063] Step 4: After the addition is completed, the temperature of the polymerization kettle is controlled at 110 degrees and the pressure is controlled at 6 MPa for 80 minutes to allow the materials in the polymerization kettle to be fully polymerized. Then add 10 parts of coupling agent diethyl adipate and continue the reaction for 30 minutes. Then add 1 part of antioxidant 2,6-di-tert-butyl-4-methylphenol and continue the reaction for 20 minutes before discharging the materials from the polymerization kettle. When discharging the materials from the polymerization kettle, add 10 parts of deionized water to the discharge pipeline to terminate the polymerization reaction of the materials.

[0064] The fifth step is to pump the discharge glue liquid from the polymerization kettle into a flash tank and keep it in the flash tank for 30 minutes, so that a large amount of C4-C8 mixed saturated aliphatic hydrocarbon solvent therein is evaporated by flash evaporation to achieve the purpose of recovering a large amount of high-purity solvent oil.

[0065] In the sixth step, the glue liquid in the flash tank is pumped into the blending tank. A static mixer is installed on the connecting pipe between the flash tank and the blending tank. When the glue liquid is in a normal conveying state, the remaining 4 parts of the antioxidant 2,6-di-tert-butyl-4-methylphenol are uniformly injected into the static mixer through a metering pump to make it uniformly mixed with the glue liquid. After that, the glue liquid is stirred in the blending tank for 3 hours.

[0066] The seventh step is to input the rubber liquid in the mixing tank into the coagulation kettle through a pump, and evaporate the C4-C8 mixed saturated aliphatic hydrocarbon solvent in the rubber liquid in the coagulation kettle into the oil-water separation tank through steam, so that only rubber and water are left in the coagulation kettle, which is called rubber particle water.

[0067] In the eighth step, the rubber particle water from the coagulation kettle is pumped into the post-processing device for washing, dehydration, expansion and drying to remove the water and residues therein and obtain pure rubber particles.

[0068] The post-processing device includes a rubber washing tank, a vibrating dehydration screen, an extrusion dehydrator, a screw high-temperature and high-pressure expander and a vibrating fluidized bed. The rubber water from the coagulation kettle is first washed with a rubber washing tank, and the temperature of the rubber washing tank is maintained above 80 degrees. Then, the rubber water is passed through a vibrating dehydration screen to remove a large amount of water, and the remaining rubber particles containing a small amount of water are sent to the extrusion dehydrator to remove the remaining water and squeeze into rubber blocks the size of a fingernail. After that, the rubber blocks are sent to the screw high-temperature and high-pressure expander, the pressure of the screw high-temperature and high-pressure expander is controlled at 50 MPa, and the die temperature is controlled at 170 degrees, so that the rubber blocks are extruded and expanded into rubber particles while all the residues therein are volatilized. Finally, the material treated by the screw high-temperature and high-pressure expander is transported to the vibrating fluidized bed, the temperature of the vibrating fluidized bed is controlled at 80 degrees, and the volatilized residues are taken away by hot air, thereby obtaining pure rubber particles.

[0069] The ninth step is to carry out briquetting, metal inspection, weighing and packaging on the rubber particles treated by the post-processing device, so as to obtain the improved food additive styrene-butadiene rubber product. Embodiment 4

[0070] The improved food additive styrene-butadiene rubber of the present embodiment comprises the following raw materials in parts by weight: 530 parts of butadiene, 470 parts of styrene, 2 parts of organic lithium initiator, 2 parts of polar additive, 1 part of solid structure regulator, 2 parts of coupling agent, 1 part of antioxidant, 3000 parts of solvent oil, and 1 part of deionized water.

[0071] The organic lithium initiator is tert-butyl lithium. The polar additive is ethylene glycol dimethyl ether. The solid structure regulator is ethylenediaminetetraacetic acid tetrasodium salt. The coupling agent is divinylbenzene. The antioxidant is 2,6-di-tert-butyl-4-methylphenol. The solvent oil is a hexane solvent.

[0072] The preparation method comprises the following steps: In the first step, 3000 parts of solvent oil hexane solvent and 1 part of solid structure regulator ethylenediaminetetraacetic acid tetrasodium salt are put into the polymerization kettle to fully dissolve the ethylenediaminetetraacetic acid tetrasodium salt. The operation method is: first heat all the hexane solvent to 75 degrees, and then put 20% of it into the polymerization kettle; then put 1 part of ethylenediaminetetraacetic acid tetrasodium salt into the polymerization kettle to fully dissolve it in 20% of the hexane solvent; finally, put the remaining 80% of the hexane solvent into the polymerization kettle.

[0073] The hexane solvent is first purified to a polymerization grade of 10ppm-15ppm using a solvent oil refining tower before being fed into the polymerization kettle.

[0074] In the second step, 2 parts of polar additive ethylene glycol dimethyl ether are added into the polymerization kettle and stirred for 3 minutes to uniformly mix the ethylene glycol dimethyl ether and the hexane solvent.

[0075] The third step is to put 2 parts of organic lithium initiator tert-butyl lithium, 530 parts of butadiene and 470 parts of styrene into the polymerization kettle and stir them evenly. The operation method is: first put 2 parts of tert-butyl lithium into the polymerization kettle and stir for 3 minutes to make it evenly mixed; at the same time, 10% of 530 parts of butadiene is evenly mixed with 470 parts of styrene. After the tert-butyl lithium is added, the mixture of butadiene and styrene is evenly input into the polymerization kettle over a period of 20 minutes. At this time, the temperature of the polymerization kettle is controlled at 95 degrees. After the input is completed, the remaining butadiene is evenly input into the polymerization kettle over a period of 40 minutes.

[0076] Before putting butadiene into the polymerization kettle, it is first purified by using a butadiene refining tower to make its purity reach 99.9% polymerization grade. Before putting styrene into the polymerization kettle, it is first purified by using a molecular sieve refining bed to make its purity reach 99.8% raw material polymerization grade. The capacity of the polymerization kettle should meet the following requirements: after all the hexane solvent, butadiene and styrene are put into the polymerization kettle, the capacity of the hexane solvent, butadiene and styrene in the polymerization kettle accounts for 70-80%.

[0077] Step 4: After the addition is completed, the temperature of the polymerization kettle is controlled at 95 degrees and the pressure is controlled at 3 MPa for 20 minutes to allow the materials in the polymerization kettle to be fully polymerized. Then add 2 parts of coupling agent divinylbenzene and continue to react for 5 minutes. Then add 0.1 parts of antioxidant 2,6-di-tert-butyl-4-methylphenol and continue to react for 5 minutes, and then the materials can be discharged from the polymerization kettle. When discharging the materials from the polymerization kettle, add 1 part of deionized water to the discharge pipeline to terminate the polymerization reaction of the materials.

[0078] The fifth step is to pump the discharging glue liquid from the polymerization kettle into a flash tank and keep it in the flash tank for 20 minutes, so that a large amount of hexane solvent therein can be evaporated by flash evaporation to achieve the purpose of recovering a large amount of high-purity solvent oil.

[0079] In the sixth step, the glue liquid in the flash tank is pumped into the blending tank. A static mixer is installed on the connecting pipe between the flash tank and the blending tank. When the glue liquid is in a normal conveying state, the remaining 0.9 parts of the antioxidant 2,6-di-tert-butyl-4-methylphenol is uniformly injected into the static mixer through a metering pump to make it uniformly mixed with the glue liquid. After that, the glue liquid is stirred in the blending tank for 1 hour.

[0080] The seventh step is to input the rubber liquid in the mixing tank into the condensation kettle through a pump, and evaporate the hexane solvent in the rubber liquid in the condensation kettle to the oil-water separation tank through steam, so that only rubber and water are left in the condensation kettle, which is called rubber particle water.

[0081] In the eighth step, the rubber particle water from the coagulation kettle is pumped into the post-processing device for washing, dehydration, expansion and drying to remove the water and residues therein and obtain pure rubber particles.

[0082] The post-processing device includes a rubber washing tank, a vibrating dehydration screen, an extrusion dehydrator, a screw high-temperature and high-pressure expander and a vibrating fluidized bed. The rubber water from the coagulation kettle is first washed with a rubber washing tank, and the temperature of the rubber washing tank is maintained above 80 degrees. Then, the rubber water is passed through a vibrating dehydration screen to remove a large amount of water, and the remaining rubber particles containing a small amount of water are sent to the extrusion dehydrator to remove the remaining water and squeeze into rubber blocks the size of a fingernail. After that, the rubber blocks are sent to the screw high-temperature and high-pressure expander. The pressure of the screw high-temperature and high-pressure expander is controlled at 35 MPa, and the die temperature is controlled at 150 degrees, so that the rubber blocks are extruded and expanded into rubber particles while all the residues therein are volatilized. Finally, the material treated by the screw high-temperature and high-pressure expander is transported to the vibrating fluidized bed. The temperature of the vibrating fluidized bed is controlled at 60 degrees, and the volatilized residues are taken away by hot air, thereby obtaining pure rubber particles.

[0083] The ninth step is to carry out briquetting, metal inspection, weighing and packaging on the rubber particles treated by the post-processing device, so as to obtain the improved food additive styrene-butadiene rubber product.

[0084] In the above embodiments, the organic lithium initiator may also use dilithium, which has similar functions to n-butyl lithium, tert-butyl lithium, isobutyl lithium or sec-butyl lithium, and will not be further described in detail with examples.

[0085] The improved food additive styrene butadiene rubber obtained by the above four embodiments is detected by nuclear magnetic hydrogen and found that the block ratio in the rubber is less than 5%, and the irregularity reaches more than 95%, which greatly improves the elasticity and tensile strength of the finished rubber. At the same time, the microstructure in the rubber is more stable, the molecular weight and the molecular structure can be fully and perfectly combined, the gel content in the colloid is greatly reduced, the elasticity and tensile strength of the finished rubber are further improved, and the user's requirements for the quality and use performance of the food rubber can be met. The chewing mouthfeel of the chewing gum and bubble gum made of the food rubber product produced by the improved food additive styrene butadiene rubber of the present invention and the preparation method thereof is more delicate, and the blowing performance and resilience are better, and the consumer can greatly experience the sense of happiness in the chewing process.

[0086] The improved food additive styrene-butadiene rubber and the preparation method thereof fill the gap in the research and development and production of domestic food rubber products, so that domestic gum base manufacturing enterprises no longer need to import a large amount of food rubber products from abroad, thus reducing the loss of national foreign exchange reserve funds.

Claims

1. An improved food additive styrene-butadiene rubber, characterized in that Contains the following raw materials in parts by weight: Butadiene 500~750 parts Styrene 250~500 parts 2~10 parts of organic lithium initiator Polar additives 2~15 parts Solid structure regulator 1~10 parts Coupling agent 2~10 parts 1~5 parts of antioxidant Solvent oil 3000~11250 parts; Wherein, the organic lithium initiator is n-butyl lithium, tert-butyl lithium, isobutyl lithium, sec-butyl lithium or dilithium; The polar additive is tetrahydrofuran, ethylene glycol dimethyl ether or diethylene glycol dimethyl ether; The solid structure regulator is sodium dodecylbenzenesulfonate or tetrasodium ethylenediaminetetraacetic acid; The coupling agent is silicon tetrachloride, divinylbenzene or diethyl adipate; The antioxidant is 2,6-di-tert-butyl-p-cresol or 2,6-di-tert-butyl-4-methylphenol; The solvent oil is cyclohexane, hexane or a C4-C8 mixed saturated aliphatic hydrocarbon solvent.

2. The improved food additive styrene-butadiene rubber as claimed in claim 1, characterized in that The raw materials also contain 1 to 10 parts of deionized water.

3. The method for preparing the improved food additive styrene-butadiene rubber according to claim 1, characterized in that The following steps are involved: The first step is to put 3000-11250 parts of solvent oil and 1-10 parts of solid structure regulator into a polymerization kettle to fully dissolve the solid structure regulator; The second step is to add 2 to 15 parts of polar additive into the polymerization kettle and stir for 3 to 10 minutes to evenly mix the polar additive with the solvent oil; The third step is to put 2-10 parts of an organic lithium initiator, 500-750 parts of butadiene and 250-500 parts of styrene into a polymerization kettle and stir them evenly; Step 4: After the addition is completed, the temperature of the polymerization kettle is controlled at 95-110 degrees and the pressure is controlled at 3-6 MPa for 20-80 minutes to allow the materials in the polymerization kettle to be fully polymerized; then 2-10 parts of coupling agent are added and the reaction is continued for 5-30 minutes; then 0.1-1 parts of antioxidant are added and the reaction is continued for 5-20 minutes before the materials are discharged from the polymerization kettle; The fifth step is to pump the discharged glue liquid from the polymerization kettle into a flash tank and store it in the flash tank for 20 to 30 minutes, so that a large amount of solvent oil therein is evaporated by flash evaporation to achieve the purpose of recovering a large amount of high-purity solvent oil; Step 6: Pump the glue liquid in the flash tank into the blending tank. A static mixer is installed on the connecting pipe between the flash tank and the blending tank. When the glue liquid is in a normal conveying state, the remaining part of 1 to 5 parts of the antioxidant is uniformly injected into the static mixer through a metering pump to make it uniformly mixed with the glue liquid; then, stir the glue liquid in the blending tank for 1 to 3 hours; The seventh step is to pump the rubber liquid in the mixing tank into the coagulation kettle through a pump, and evaporate the solvent oil in the rubber liquid in the coagulation kettle to the oil-water separation tank through steam, so that only rubber and water are left in the coagulation kettle, which is called rubber particle water; In the eighth step, the rubber particles water from the coagulation reactor is pumped into the post-processing device, and the rubber particles are washed, dehydrated, expanded and dried to remove the water and residues therein to obtain pure rubber particles; The ninth step is to carry out briquetting, metal inspection, weighing and packaging on the rubber particles treated by the post-processing device, so as to obtain the improved food additive styrene-butadiene rubber product.

4. The method for preparing the improved food additive styrene-butadiene rubber as claimed in claim 3, characterized in that In the first step, all the solvent oil is first heated to 75-85 degrees, and then 20% of it is added to the polymerization kettle; then 1-10 parts of the solid structure regulator are added to the polymerization kettle to make it fully dissolved in the 20% solvent oil; finally, the remaining 80% of the solvent oil is all added to the polymerization kettle.

5. The method for preparing the improved food additive styrene-butadiene rubber as claimed in claim 3, characterized in that In the third step, 2 to 10 parts of an organic lithium initiator are first added to a polymerization kettle and stirred for 3 to 5 minutes to make the mixture uniformly mixed; at the same time, 10 to 90% of 500 to 750 parts of butadiene are uniformly mixed with 250 to 500 parts of styrene; after the addition of the organic lithium initiator is completed, the mixture of butadiene and styrene is uniformly introduced into the polymerization kettle over a period of 20 to 90 minutes, and the temperature of the polymerization kettle is controlled at 95 to 110 degrees; after the addition is completed, the remaining butadiene is uniformly introduced into the polymerization kettle over a period of 5 to 40 minutes.

6. The method for preparing the improved food additive styrene-butadiene rubber as claimed in claim 3, characterized in that In the fourth step, when the polymerization reactor is discharged, 1 to 10 parts of deionized water are added to the discharge pipeline to terminate the polymerization reaction of the material.

7. The method for preparing the improved food additive styrene-butadiene rubber according to any one of claims 3 to 6, characterized in that In the first step, before the solvent oil is put into the polymerization reactor, it is first purified to a polymerization grade of 10ppm-15ppm using a solvent oil refining tower.

8. The method for preparing the improved food additive styrene-butadiene rubber according to any one of claims 3 to 6, characterized in that In the third step, before being fed into the polymerization kettle, butadiene is first purified by using a butadiene refining tower to achieve a polymerization grade purity of 99.9%; before being fed into the polymerization kettle, styrene is first purified by using a molecular sieve refining bed to achieve a raw material polymerization grade purity of 99.8%.

9. The method for preparing the improved food additive styrene-butadiene rubber according to any one of claims 3 to 6, characterized in that The capacity of the polymerization kettle should meet the following requirements: after all the solvent oil, butadiene and styrene are put into the polymerization kettle, the capacity of the solvent oil and the materials in the polymerization kettle accounts for 70-80%.

10. The method for preparing the improved food additive styrene-butadiene rubber according to any one of claims 3 to 6, characterized in that The post-processing device in the eighth step includes a glue washing tank, a vibrating dehydration screen, an extrusion dehydrator, a screw high-temperature and high-pressure expander and a vibrating fluidized bed; The colloid water from the coagulation kettle is first washed in a washing tank, and the temperature of the washing tank is kept above 80 degrees; Next, the water in the colloid particles is removed by a vibrating dehydration screen, and the remaining colloid particles containing a small amount of water are sent to an extrusion dehydrator to remove the remaining water and squeezed into colloid blocks the size of a fingernail; Afterwards, the rubber block is sent to a screw high-temperature and high-pressure expander. The pressure of the screw high-temperature and high-pressure expander is controlled at 35-50 MPa, and the die temperature is controlled at 150-170 degrees, so that the rubber block is squeezed and expanded into rubber particles while all the residues therein are volatilized; Finally, the material treated by the screw high-temperature and high-pressure expander is transported to the vibrating fluidized bed. The temperature of the vibrating fluidized bed is controlled at 60~80 degrees, and the volatilized residues are taken away by hot air to obtain pure rubber particles.