CN113292665A - Special resin for polyvinyl chloride with medium and high polymerization degrees - Google Patents

Abstract

The invention relates to a medium and high polymerization degree polyvinyl chloride special resin which is mainly prepared from the following raw materials in parts by weight: 100 parts of vinyl chloride monomer, 130 parts of deionized water 115-containing water, 0.006-0.02 part of neutralizer, 0.04-0.059 part of dispersant A, 0.017-0.036 part of dispersant B, 0.014-0.023 part of surfactant, 0.02-0.029 part of initiator A and 0.024-0.033 part of initiator B. The invention can be widely applied to the production process of the special resin for chloridizing the polyvinyl chloride by the gas-solid phase method.

Description

Special resin for polyvinyl chloride with medium and high polymerization degrees

Technical Field

The invention relates to the technical field of polymer chemical industry, in particular to a production method of special resin for polyvinyl chloride with medium and high polymerization degrees.

Background

Chlorinated polyvinyl chloride (CPVC) is obtained by further chlorinating polyvinyl chloride (PVC), and is a novel high-molecular elastomer material between rubber and plastics. After the PVC resin is chlorinated, the irregularity of molecular bonds is increased, the polarity is enhanced, the solubility of the resin is increased, and the chemical stability is improved, so that the heat resistance, the corrosion resistance of acid, alkali, salt, an oxidant and the like of the material are improved, compared with PVC, the heat resistance, the corrosion resistance, the flame-retardant self-extinguishing property, the mechanical property and the like of CPVC are greatly improved, and the CPVC resin is widely applied to the fields of building materials, electrical, chemical engineering, metallurgy, medicine, coatings and the like.

At present, the quality of domestic CPVC resin has a large difference from that of imported resin, and one reason for the difference is that high-quality special PVC resin for chlorination is lacked in China. The development of PVC resin suitable for chlorination is a development requirement of CPVC industry and a development direction of PVC manufacturing enterprises.

The diffusion speed of chlorine molecules in PVC resin particles is an important factor for determining the chlorination reaction rate and the product quality. The diffusion of chlorine molecules in PVC resin particles can be divided into three stages from outside to inside, namely stage 1, the chlorine molecules enter the pores in the particles from the thin layer or the rupture part of the membrane of the PVC resin particles; stage 2, chlorine molecules entering the interior of the granules continuously diffuse to the deep part of the granules along the unobstructed pores in the granules and contact the surfaces of primary particles and primary particle aggregates surrounding the pores; and 3, diffusing chlorine molecules on the inner surface of the PVC resin particles into the primary particles and the aggregates. The diffusion process of chlorine gas into PVC granules puts 3 requirements on the structural characteristics of PVC resin special for chlorination: firstly, the surface of the resin particles has no or few skins, which is beneficial to the diffusion of chlorine molecules to the interior; secondly, the pores of the resin particles are uniform, and the average particle size is small; the more uniform the pore distribution, the smaller the average diameter, the larger the specific surface area within the particle, and the smaller the average depth to which chlorine gas needs to diffuse into the primary particles in stage 3; because the consumption speed of chlorine gas in the primary particles is greater than the diffusion supplement speed, the reduction of the diffusion depth is beneficial to uniform chlorination; thirdly, the primary particles and the aggregates have loose structures, the more loose the structures are, the faster the diffusion speed of chlorine molecules is, and the smaller the concentration gradient of the chlorine in the primary particles is.

Chinese invention patent CN112029137A discloses a preparation method of special PVC resin for chlorination, which comprises the following steps: adding the wet material of the water-containing PVC resin centrifuged by the PVC polymerization production system into a closed container with stirring, adding the functional organic solvent, uniformly stirring and mixing, and performing microwave heating and drying on the uniformly mixed primary material to obtain the special PVC resin for chlorination. The PVC resin wet material particles obtained by the aqueous phase polymerization method contain a large amount of water, water is changed into water vapor during microwave heating, the structure around the PVC resin particles is pressed to be closed at the initial stage of the water vapor, the constraint of the PVC resin particles and the external involucra of the particles is broken at the later stage, the PVC resin particles and the external involucra of the particles escape quickly, the special chlorination resin with loose particle structure, high plasticizer oil absorption rate and large specific surface area is obtained, the production requirement of the CPVC resin can be met, and the chlorination reaction is more favorably carried out.

The Chinese invention patent CN112029138A discloses a preparation method of polyvinyl chloride resin special for chlorination, which comprises the following steps: adding the wet material of the water-containing PVC resin centrifuged by the PVC polymerization production system into a closed container with a stirrer, adding a functional organic solvent, uniformly stirring and mixing, freezing, and carrying out microwave heating and drying on the frozen low-temperature primary material to obtain the special PVC resin for chlorination. The inside of PVC resin wet material granule that aqueous phase polymerization method obtained contains a large amount of moisture, water becomes ice to the inside aperture inflation effect of PVC resin granule when freezing, ice sublimates to vapor when microwave heating, the initial stage oppression PVC resin granule structure around closes, later stage breaks through the constraint of PVC resin granule and the outside involucra of granule, the rapid escape, it is loose to obtain the granular structure, the plasticizer oil absorption rate is high, the big special resin of chlorination of specific surface area, can satisfy the production needs of CPVC resin, more do benefit to going on of chlorination.

The above patent introduces the technology of expanding aperture by moisture expansion in the freezing aperture of wet material cake or expanding aperture by microwave heating and rapid gasification of wet material cake, or the technology of combining the freezing and icing expansion aperture and the microwave heating rapid gasification expansion aperture is adopted, the technology expands the aperture of the original PVC resin particles, improves the size and the volume of the original aperture, but does not fundamentally solve the problems of porosity abundance and uniformity, and moreover, there is a description in the prior art that in the suspension polymerization process, the pore structure is improved from the surface skin structure of the PVC resin particles by adding surfactants such as an anti-fisheye agent, a regulator, a dispersant and the like, can obviously improve and obviously change the particle morphology of the polyvinyl chloride resin on a macroscopic scale, adjust the particle size distribution and the shape roundness, the method also has better improvement on the internal gap structure, but lacks a control means on the resin deep micro-nano structure.

The CPVC resin is industrially produced by three methods: solvent method, water phase method, gas-solid phase method, wherein the gas-solid phase method is cleaner and more efficient. In the process for producing chlorinated polyvinyl chloride by a gas-solid phase method, gas-phase chlorine molecules enter through inner pore channels of particles to perform grafting reaction with PVC molecular chains, the grafting rate and the grafting uniformity are directly influenced by the abundance of pores and the uniformity of pores, meanwhile, the grafting reaction heat is removed by chlorine gas of circulating vulcanization, the polyvinyl chloride resin is produced by a suspension method process, the stirring speed of a polymerization kettle and the type and the dosage of a dispersing agent are regulated and controlled, can change the particle shape of the polyvinyl chloride resin on a macroscopic scale, adjust the particle size distribution and the shape roundness, the internal void structure is also well improved, but the regulation and control of the resin deep micro-nano structure are not easy to complete, the specificity of the PVC resin produced by the prior art on the production and application of chlorinated polyvinyl chloride is not strong, and particularly, the chlorinated polyvinyl chloride resin is difficult to remove heat by adopting a gas-solid phase chlorination process, so that the thermal stability of the chlorinated polyvinyl chloride resin is poor.

The production temperature of the polyvinyl chloride resin with medium and high polymerization degrees is relatively low, the surface tension of water and vinyl chloride at low temperature is large, the consumption of a dispersing agent is large, the regularity of particles is poor, the apparent density is relatively low, the surface of PVC particles is covered by the dispersing agent to form a complete membrane structure, and the vulcanization of materials and the diffusion of chlorine in the gas-solid phase chlorination process are influenced.

Disclosure of Invention

In order to solve the technical problems, the invention provides the special resin for the polyvinyl chloride with the medium and high polymerization degrees, which meets the chlorination process of a gas-solid phase method, reduces the degree of covering the surface of the special resin with a film, reduces the degree of bonding of sub-particle structures inside and outside particles, and improves the abundance and uniformity of gaps among micro-nano structures inside the particles, so that chlorine can be effectively diffused into PVC particles to perform grafting reaction in the gas-solid phase chlorination process, and meanwhile, the reaction heat is favorably removed by outward diffusion through abundant micro-pore structures.

The technical scheme adopted by the invention for solving the technical problems is as follows: the medium and high polymerization degree polyvinyl chloride special resin is mainly prepared from the following raw materials in parts by weight: 100 parts of vinyl chloride monomer, 130 parts of deionized water 115-containing water, 0.006-0.02 part of neutralizer, 0.04-0.059 part of dispersant A, 0.017-0.036 part of dispersant B, 0.014-0.023 part of surfactant, 0.02-0.029 part of initiator A and 0.024-0.033 part of initiator B.

In the medium and high polymerization degree polyvinyl chloride special resin, the dispersant A is a polyvinyl alcohol dry base with 65-75% of alcoholysis degree; the dispersant B is hydroxypropyl methyl cellulose dry base; the surfactant is polyvinyl alcohol dry base with alcoholysis degree of 35-50% and distributed by blocks; the initiator A is tert-butyl peroxyneodecanoate dry basis; the initiator B is cumyl peroxyneodecanoate dry basis; the neutralizing agent is 3% -5% carbonate solution. The polyvinyl alcohol with 35-50% of low alcoholysis degree block distribution is selected, more acetyl groups and less hydroxyl blocks are distributed on a molecular chain segment of PVA, the acetyl groups have good lipophilicity and can quickly adsorb the surface of a monomer liquid drop and even be dissolved in the monomer, the hydroxyl groups have oleophobic property, if the polyvinyl chloride with low alcoholysis degree can be dissolved in the monomer liquid drop, the oleophobic hydroxyl groups in the liquid drop can continuously form obstruction in the liquid drop, the cohesion among the conglomerates is weakened in the polymer forming process, and the internal pore volume of PVC particles is adjusted.

The special resin for polyvinyl chloride with medium and high polymerization degree is prepared by sequentially adding cold deionized water, hot deionized water, a neutralizer, a dispersant A, a surfactant, a dispersant B, an initiator A, an initiator B and a vinyl chloride monomer into a polymerization kettle, and uniformly mixing the materials; continuously and constantly heating the materials in the polymerization kettle by using a polymerization kettle jacket and a hot circulating water system, and activating the materials in the polymerization kettle; the temperature of materials in the polymerization kettle reaches 55-59 ℃ of reaction temperature, jacket hot water is switched to circulating cooling water, the reaction temperature of the polymerization kettle is controlled, the reaction lasts for 60-90 min, and then the reaction temperature is changed to 45-52 ℃; after reacting for 4.5-6h, discharging, stripping and drying the PVC slurry to obtain the PVC resin with the average polymerization degree of 1100-1350. A first stage of variable temperature polymerization, a polymerization reaction stage at constant temperature of 57 ℃, the optimal time of constant temperature reaction is 60min, and the cooling rate of circulating cooling water at 7 ℃ in the variable temperature process is controlled at 0.5 ℃/min. The method for producing the polyvinyl chloride resin with medium and high polymerization degrees by a low temperature method has the defects of large consumption of the dispersing agent, poor particle regularity, low apparent density, high coverage rate of the surface of PVC particles by the dispersing agent and the like.

The medium and high polymerization degree polyvinyl chloride special resin has the temperature-changing polymerization reaction second stage, the constant temperature reaction temperature is controlled to be 49.5-51.5 ℃, the reaction time is 5-7h, and the 1200 type chlorination special polyvinyl chloride resin with the average polymerization degree of 1150-1250 can be obtained.

The polyvinyl chloride special resin with medium and high polymerization degree is characterized in that the vinyl chloride monomer added into the polymerization kettle comprises recycled vinyl chloride monomer and fresh vinyl chloride monomer.

The cold deionized water and the hot deionized water are proportionally adjusted to the material temperature and controlled to be 32-36 ℃; the neutralizing agent is used for adjusting the pH value of the material to 6.5-8.0.

In the material activation process of the medium and high polymerization degree polyvinyl chloride special resin, the temperature of circulating water is controlled to be 80-85 ℃, and the continuous constant heating rate is 0.5-2.0 ℃/min. Vinyl chloride polymerization is a free radical chain polymerization. The extent of free radical formation controls the rate of strand initiation. After chain initiation, vinyl chloride chain growth occurs. After the free radical of the PVC chain grows to a certain degree, the free radical tends to precipitate. After continuing to grow into the original particles, the precipitate is easily re-precipitated. The reaction is difficult or even impossible to initiate at very low temperature growth rates. At too fast a temperature growth rate, the rate of initiator decomposition into free radicals increases and the rate of molecular collision chain growth also increases. When a large number of primary particles are formed simultaneously, the system becomes extremely viscous and unstable. When the rapid sedimentation is carried out, the adhesive is easy to adhere to form a whole body to close the pore channel. By controlling the heating rate, the materials are slowly and stably activated, the initial reaction rate is properly adjusted, the original particle forming rate is controlled, and the polyvinyl chloride resin is slowly precipitated. When the primary particles form primary particle cores, the primary particles continue to grow into primary particles, and the primary particles grow up and are flocculated into agglomerates again. In order to avoid the concentration of the formation stage of the micro-nano structure, the low-temperature activation treatment is adopted to regulate and control the chain initiation and chain growth rate, reduce the bonding of original particles and reduce the aggregation degree of primary particles in an unstable period, thereby achieving the purpose of regulating and controlling the micro-nano structure of the PVC resin particles.

The medium and high polymerization degree polyvinyl chloride special resin has the temperature-changing polymerization reaction second stage, the constant temperature reaction temperature is controlled to be 49.5-51.5 ℃, the reaction time is 5-7h, and the 1200 type chlorination special polyvinyl chloride resin with the average polymerization degree of 1150-1250 can be obtained. The optimal reaction temperature of the second stage of the variable temperature polymerization of the 1200-type chlorinated special polyvinyl chloride resin is 50.5 +/-1 ℃, and the total reaction time is about 6 hours, so that the chlorinated special polyvinyl chloride resin with the average polymerization degree of 1150-1250 can be obtained.

The medium and high polymerization degree polyvinyl chloride special resin is subjected to temperature-changing polymerization reaction at the second stage, the constant temperature reaction temperature is controlled to be 48.5-50.5 ℃, and the reaction time is 5-7 hours, so that the 1300 type special polyvinyl chloride resin with the average polymerization degree of 1250-. The optimal reaction temperature of the second stage of the 1300 type special polyvinyl chloride resin temperature-variable polymerization is 49.5 +/-1 ℃, the total reaction time is about 6.5h, and the special polyvinyl chloride resin for chlorination with the average polymerization degree of 1250-.

The fluctuation deviation of the reaction temperature of the polymerization kettle is controlled to be +/-0.5 ℃ in the polymerization reaction control process of the medium-high polymerization degree polyvinyl chloride special resin.

The discharging, steam stripping and drying processes of the PVC slurry of the medium and high polymerization degree polyvinyl chloride special resin are as follows: when the reaction pressure of the polymerization kettle is reduced to-0.05 MPa to-0.07 MPa, adding a terminator into the polymerization kettle after the polymerization reaction is finished, discharging the PVC slurry, recovering unreacted vinyl chloride monomers, removing PVC and residual monomers in water from the PVC slurry through steam stripping, removing mother liquor in the slurry, and drying the material cake to obtain the finished product of PVC resin; the specific surface area of the PVC resin is 3-6m²/g。

The percentages referred to in the invention are mass percentages.

Compared with the prior art, the invention provides the polyvinyl chloride resin with medium and high polymerization degrees, and the PVC resin with the average polymerization degree of 1100-1350 is obtained by the invention, the PVC granulation is finished at a proper temperature by adopting a temperature-changing polymerization mode, the dosage of the dispersing agent is reduced, the grafting rate of the polyvinyl alcohol and the chloroethylene of the dispersing agent is reduced, and the coverage rate of a skin membrane is reduced; by selecting a surfactant with a block distribution structure, a protection structure is formed inside and outside a vinyl chloride monomer liquid drop by a special group possessed by the surfactant, so that the sub-particle structure adhesion degree inside and outside particles is reduced; the growth process of the PVC from the primary particles to the aggregates is adjusted by controlling the chemical reaction kinetics, so that the aggregation density of the primary particles is reduced, the strength of the flocculated primary particles is improved, the adhesion degree of the flocculated primary particles during the formation of the aggregates is reduced, and more and uniform pores are formed among micro-nano structures such as PVC aggregates.

The method overcomes the defects that suspension polymerization PVC resin particles are irregular, the coating area is large, the internal pore structure is low and uneven in the traditional process, is intervened in the PVC particle synthesis stage, macroscopically regulates the particle structure form by using a dispersing agent and stirring, microscopically controls the precipitation polymerization rate of the micro-nano structure to regulate the micro-nano structure, and the two are synchronously carried out, so that the using amount of the dispersing agent in suspension polymerization is reduced, the PVC resin forms a coating structure, the problems of insufficient abundance and uniformity of pores in the production of PVC resin by a general suspension method are solved, the diffusibility of special resin to small molecular substances is improved, and chlorine can be conveniently deeply diffused into the particles and can be subjected to chlorination reaction to the deep layer of the particles during chlorination grafting reaction. The BET specific surface area of the PVC resin prepared by the invention can reach 3-6m2/g, and the BET specific surface area of the PVC resin produced by the original process is 0.7-1.0 m 2/g. The invention can be widely applied to the production process of special polyvinyl chloride resin for chlorination by a gas-solid phase method.

Detailed Description

Example 1: the medium and high polymerization degree polyvinyl chloride special resin is mainly prepared from the following raw materials in parts by weight: 100 parts of vinyl chloride monomer, 115 parts of deionized water, 0.006 part of neutralizer, 0.04 part of dispersant A, 0.017 part of dispersant B, 0.014 part of surfactant, 0.02 part of initiator A and 0.024 part of initiator B.

Example 2: the medium and high polymerization degree polyvinyl chloride special resin is mainly prepared from the following raw materials in parts by weight: 100 parts of vinyl chloride monomer, 120 parts of deionized water, 0.01 part of neutralizer, 0.05 part of dispersant A, 0.025 part of dispersant B, 0.02 part of surfactant, 0.025 part of initiator A and 0.03 part of initiator B.

Example 3: the medium and high polymerization degree polyvinyl chloride special resin is mainly prepared from the following raw materials in parts by weight: 100 parts of vinyl chloride monomer, 130 parts of deionized water, 0.02 part of neutralizer, 0.059 part of dispersant A, 0.036 part of dispersant B, 0.023 part of surfactant, 0.029 part of initiator A and 0.033 part of initiator B.

Example 4: the special resin for the polyvinyl chloride with medium and high polymerization degrees sequentially comprises the following steps: preparing an auxiliary agent: the method comprises the preparation of a dispersant A, a dispersant B, a surfactant, an initiator and a neutralizing agent; feeding a polymerization kettle: spraying an anti-sticking kettle agent on the inner wall of a polymerization kettle, then completely discharging residual liquid of the kettle, starting the polymerization kettle to stir, sequentially adding 125 parts of deionized water, 0.02 part of a neutralizing agent, 0.05 part of a dispersing agent A, 0.02 part of a surfactant, 0.036 part of a dispersing agent B, 0.025 part of an initiator A and 100 parts of a vinyl chloride monomer into the polymerization kettle, and uniformly mixing the materials; material activation: continuously and constantly heating the materials in the polymerization kettle by using a polymerization kettle jacket and a hot circulating water system, and activating the materials in the polymerization kettle; controlling the temperature-changing polymerization reaction: a first stage of variable-temperature polymerization, wherein when the temperature of materials in a polymerization kettle reaches 57 ℃, the constant-temperature polymerization reaction is controlled for 60 min; the second stage of temperature-changing polymerization, wherein the reaction temperature is changed to 50 ℃ and the reaction lasts for 6 hours; the temperature reduction rate of circulating cooling water at 7 ℃ in the temperature changing process is controlled to be 0.5 ℃/min, and the PVC slurry is discharged, stripped and dried to obtain the PVC resin with the average polymerization degree of 1100-1350.

Example 5: the medium and high polymerization degree polyvinyl chloride special resin is mainly prepared from the following raw materials in parts by weight: 26.5t of vinyl chloride monomer (including recycled vinyl chloride monomer and fresh vinyl chloride monomer), 32t of deionized water (including cold deionized water and hot deionized water), 4.80 kg of neutralizing agent, 14.40kg of dispersant A, 8.96kg of dispersant B, 5.76kg of surfactant, 7.04kg of initiator A, and 8.00kg of initiator B.

Another embodiment is different in that the dispersant A is polyvinyl alcohol dry base with alcoholysis degree of 65% -75%; the dispersant B is hydroxypropyl methyl cellulose dry base; the surfactant is polyvinyl alcohol dry base with alcoholysis degree of 35-50% and distributed by blocks; the initiator A is cumyl peroxyneodecanoate dry basis; the initiator B is tert-butyl peroxyneodecanoate dry basis; the neutralizing agent is 3% -5% carbonate solution.

The other embodiment is different in that cold deionized water, hot deionized water, a neutralizer, a dispersant A, a surfactant, a dispersant B, an initiator A, an initiator B and vinyl chloride monomer are added into a polymerization kettle in sequence, and the materials are uniformly mixed; continuously and constantly heating the materials in the polymerization kettle by using a polymerization kettle jacket and a hot circulating water system, and activating the materials in the polymerization kettle; the temperature of materials in the polymerization kettle reaches 55 ℃ reaction temperature, jacket hot water is switched to circulating cooling water, the reaction temperature of the polymerization kettle is controlled, the reaction is carried out for 60min, and then the reaction temperature is changed to 45 ℃; after 4.5h of reaction, the PVC slurry is discharged, stripped and dried to obtain the PVC resin with the average polymerization degree of 650-850.

The other embodiment is different in that cold deionized water, hot deionized water, a neutralizer, a dispersant A, a surfactant, a dispersant B, an initiator A, an initiator B and vinyl chloride monomer are added into a polymerization kettle in sequence, and the materials are uniformly mixed; continuously and constantly heating the materials in the polymerization kettle by using a polymerization kettle jacket and a hot circulating water system, and activating the materials in the polymerization kettle; the temperature of materials in the polymerization kettle reaches 59 ℃ reaction temperature, jacket hot water is switched to circulating cooling water, the reaction temperature of the polymerization kettle is controlled, the reaction is carried out for 90min, and then the reaction temperature is changed to 52 ℃; after reacting for 6h, discharging, stripping and drying the PVC slurry to obtain the PVC resin with the average polymerization degree of 1100-1350.

The other embodiment is different in that cold deionized water, hot deionized water, a neutralizer, a dispersant A, a surfactant, a dispersant B, an initiator A, an initiator B and vinyl chloride monomer are added into a polymerization kettle in sequence, and the materials are uniformly mixed; continuously and constantly heating the materials in the polymerization kettle by using a polymerization kettle jacket and a hot circulating water system, and activating the materials in the polymerization kettle; the temperature of materials in the polymerization kettle reaches 57 ℃ reaction temperature, jacket hot water is switched to circulating cooling water, the reaction temperature of the polymerization kettle is controlled, the reaction is carried out for 80min, and then the reaction temperature is changed to 50 ℃; after 5h of reaction, discharging, stripping and drying the PVC slurry to obtain the PVC resin with the average polymerization degree of 1100-1350.

Another embodiment is different in that in the second stage of the temperature-variable polymerization, the temperature of the constant-temperature polymerization is controlled at 49.5 ℃ and the reaction time is 5, so that the 1200-type chlorinated polyvinyl chloride resin special for chlorination with the average polymerization degree of 1150-1250 can be obtained.

Another embodiment is different in that in the second stage of the temperature-variable polymerization reaction, the temperature of the constant-temperature reaction is controlled at 51 ℃ and the reaction time is 6 hours, so that the 1200-type special chlorinated polyvinyl chloride resin with the average polymerization degree of 1150-1250 can be obtained.

Another embodiment is different in that in the second stage of the temperature-variable polymerization, the temperature of the constant-temperature polymerization is controlled at 51.5 ℃ and the reaction time is 7 hours, so that the 1200-type special polyvinyl chloride resin for chlorination with the average polymerization degree of 1150-1250 can be obtained.

Another embodiment is different in that in the second stage of the temperature-variable polymerization reaction, the temperature of the constant-temperature reaction is controlled at 48.5 ℃ and the reaction time is 5 hours, so that the 1300 type chlorinated special polyvinyl chloride resin with the average polymerization degree of 1250-.

Another embodiment is different in that in the second stage of the temperature-variable polymerization reaction, the temperature of the constant-temperature reaction is controlled at 50 ℃ and the reaction time is 6 hours, so that the 1300 type chlorinated special polyvinyl chloride resin with the average polymerization degree of 1250-.

Another embodiment is different in that in the second stage of the temperature-variable polymerization reaction, the temperature of the constant-temperature reaction is controlled at 50.5 ℃ and the reaction time is 7 hours, so that the 1300 type chlorinated special polyvinyl chloride resin with the average polymerization degree of 1250-.

The difference of another embodiment is that the material temperature of the cold deionized water and the hot deionized water is adjusted to be 32 ℃ according to the proportion; the neutralizing agent adjusts the pH value of the material to 6.5.

The difference of another embodiment is that the material temperature of the cold deionized water and the hot deionized water is adjusted to 35 ℃ according to the proportion; the neutralizing agent adjusts the pH value of the material to 7.0.

The difference of another embodiment is that the material temperature of the cold deionized water and the hot deionized water is adjusted to be 36 ℃ according to the proportion; the neutralizing agent adjusts the pH value of the material to 8.0.

Another embodiment is different in that the temperature of the circulating water is controlled at 80 ℃ in the material activation process, and the constant heating rate is 0.5 ℃/min.

Another example is different in that the temperature of the circulating water is controlled at 83 ℃ during the activation of the material, and the constant heating rate is 1.2 ℃/min.

Another example is different in that the temperature of the circulating water is controlled at 85 ℃ during the activation of the material, and the constant temperature rising rate is 2.0 ℃/min.

Claims (9)

1. The special resin for the polyvinyl chloride with medium and high polymerization degrees is characterized by being prepared from the following raw materials in parts by mass: 100 parts of vinyl chloride monomer, 130 parts of deionized water 115-containing water, 0.006-0.02 part of neutralizer, 0.04-0.059 part of dispersant A, 0.017-0.036 part of dispersant B, 0.014-0.023 part of surfactant, 0.02-0.029 part of initiator A and 0.024-0.033 part of initiator B.

2. The special resin for polyvinyl chloride with medium and high polymerization degree according to claim 1, which is characterized in that: the dispersant A is a polyvinyl alcohol dry base with alcoholysis degree of 65-75%; the dispersant B is hydroxypropyl methyl cellulose dry base; the surfactant is polyvinyl alcohol dry base with alcoholysis degree of 35-50% and distributed by blocks; the initiator A is tert-butyl peroxyneodecanoate dry basis; the initiator B is cumyl peroxyneodecanoate dry basis; the neutralizing agent is 3% -5% carbonate solution.

3. The special resin for polyvinyl chloride with medium and high polymerization degree according to claim 1 or 2, which is characterized in that: sequentially adding cold deionized water, hot deionized water, a neutralizer, a dispersant A, a surfactant, a dispersant B, an initiator A, an initiator B and a vinyl chloride monomer into a polymerization kettle, and uniformly mixing the materials; continuously and constantly heating the materials in the polymerization kettle by using a polymerization kettle jacket and a hot circulating water system, and activating the materials in the polymerization kettle; the temperature of materials in the polymerization kettle reaches 55-59 ℃ of reaction temperature, jacket hot water is switched to circulating cooling water, the reaction temperature of the polymerization kettle is controlled, the reaction lasts for 60-90 min, and then the reaction temperature is changed to 45-52 ℃; after reacting for 4.5-6h, discharging, stripping and drying the PVC slurry to obtain the PVC resin with the average polymerization degree of 1100-1350.

4. The special resin for polyvinyl chloride with medium and high polymerization degree according to claim 3, which is characterized in that: in the second stage of the variable temperature polymerization reaction, the constant temperature reaction temperature is controlled to be 49.5-51.5 ℃, and the reaction time is 5-7 hours, so that the 1200 type special polyvinyl chloride resin for chlorination with the average polymerization degree of 1150-1250 can be obtained.

5. The method for producing the special resin for the polyvinyl chloride with the medium and high polymerization degree according to claim 1, wherein the method comprises the following steps: in the second stage of the variable temperature polymerization reaction, the constant temperature reaction temperature is controlled to be 48.5-50.5 ℃, and the reaction time is 5-7 hours, so that the 1300 type special polyvinyl chloride resin for chlorination with the average polymerization degree of 1250-1350 can be obtained.

6. The method for producing special resin for polyvinyl chloride with medium and high polymerization degree according to any one of claims 1 to 5, wherein: the vinyl chloride monomer added into the polymerization kettle comprises recycled vinyl chloride monomer and fresh vinyl chloride monomer.

7. The method for producing the special resin for polyvinyl chloride with medium and high polymerization degree according to claim 6, characterized in that: the cold deionized water and the hot deionized water are proportionally adjusted to the material temperature of 32-36 ℃; the neutralizing agent is used for adjusting the pH value of the material to 6.5-8.0.

8. The method for producing the special resin for polyvinyl chloride with medium and high polymerization degree according to claim 7, characterized in that: in the material activation process, the temperature of circulating water is controlled to be 80-85 ℃, and the constant temperature rise rate is 0.5-2.0 ℃/min.

9. The method for producing the special resin for the polyvinyl chloride with the medium and high polymerization degree according to claim 8, wherein the discharging, steam stripping and drying processes of the PVC slurry comprise the following steps: when the reaction pressure of the polymerization kettle is reduced to-0.05 MPa to-0.07 MPa, adding a terminator into the polymerization kettle after the polymerization reaction is finished, discharging the PVC slurry, recovering unreacted vinyl chloride monomers, removing PVC and residual monomers in water from the PVC slurry through steam stripping, removing mother liquor in the slurry, and drying the material cake to obtain the finished product of PVC resin; the specific surface area of the PVC resin is 3-6m²/g。