Special polyvinyl chloride resin for gas-solid phase method chlorination as well as preparation method and application of special polyvinyl chloride resin

Abstract

The invention belongs to the technical field of polymer chemical raw materials and resin synthesis, particularly relates to polyvinyl chloride (PVC) resin, more particularly relates to special polyvinyl chloride resin for gas-solid phase method chlorination, and further discloses a preparation method of the special polyvinyl chloride resin. According to the preparation method of the special polyvinyl chloride resin for gas-solid phase method chlorination, on the basis of a traditional polyvinyl chloride resin synthesis process, a polybasic polyvinyl alcohol composite dispersion system with high and low polymerization degrees and alcoholysis degrees is adopted, and an antistatic agent is added in a polymerization mode at the initial stage of polymerization; the antistatic agent can be adsorbed and grafted on the surfaces of resin particles and distributed in the particles, so that the special polyvinyl chloride resin with a special particle structure is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer chemical raw materials and resin synthesis, and specifically relates to a polyvinyl chloride resin (PVC), and more specifically to a polyvinyl chloride resin specially used for gas-solid phase chlorination, and further discloses a preparation method thereof. Background Art

[0002] Chlorinated polyvinyl chloride (PVC) resin is mainly used for chlorination modification to produce chlorinated polyvinyl chloride (CPVC) resin. Compared with PVC resin, CPVC resin has significantly improved in heat resistance, flame retardancy, chemical corrosion resistance and mechanical strength. CPVC resin has a wide range of applications, including hot and cold water pipes and fittings, fire protection pipes, heat-resistant and corrosion-resistant pipes / fittings for chemical industry, buried high-voltage power cable casings, and oilfield crude oil gathering pipes. It is a new type of engineering plastic that has developed rapidly in recent years and has broad market prospects.

[0003] The performance of PVC resin, the raw material for CPVC production, is the main factor that directly affects the quality of CPVC resin. According to the performance requirements of CPVC resin, it is necessary to construct a special PVC particle structure with the characteristics of thin particle film, low coverage, loose resin particles, many internal pores, uniform structure, fast plasticizer absorption rate, good particle regularity and uniform particle size distribution.

[0004] At present, the production methods of CPVC resin in China mainly include water suspension method and gas-solid method; among them, the production technology of water suspension method is mature and has formed a scale, while the gas-solid method chlorination process is more in line with the development trend of clean and environmental protection because it does not require a dispersion medium, and is directly chlorinated in a reactor or fluidized bed, as well as the advantages of short production process flow, low environmental pollution, and basically no "three wastes" discharge. However, although the gas-solid method production process has the advantages of clean and environmental protection, its reaction process is difficult to control, and there are defects such as slow chlorination reaction, poor product uniformity, and high difficulty in production process technology. It is necessary to solve the problems of controlling the fluidity of materials, heat transfer during the chlorination reaction process, and uniformity of product chlorination. Therefore, the gas-solid method production process puts forward higher requirements on the particle morphology, average particle size, dry flow and chlorination performance of PVC resin. At present, the domestic gas-solid method CPVC production process adopts the technology of France ARKEMA Company, and the raw materials used are bulk PVC chlorination special resins, while the suspension method PVC resin cannot meet the requirements of the gas-solid method chlorination process due to factors such as fluidity and particle structure.

[0005] For example, Chinese patent CN104277169A discloses a method for producing a chlorinated polyvinyl chloride resin, by adding a regulator and a dispersant twice in the middle stage of polymerization, a chlorinated PVC resin with a loose structure, high porosity, high oil absorption rate and thin surface film is produced. Another example is Chinese patent CN108192001B discloses a method for producing a chlorinated polyvinyl chloride resin, by premixing a quality agent and a VCM monomer evenly, and then polymerizing, the so-called quality agent is a polyvinyl alcohol with a low degree of polymerization and a low degree of alcoholysis, and the prepared chlorinated polyvinyl chloride resin particles have a regular morphology, a loose structure, a uniform pore distribution, and a high particle size concentration. Furthermore, the preparation method of the chlorinated polyvinyl chloride resin disclosed in Chinese patent CN112029138A, taking a centrifuged PVC resin containing water, adding a functional organic solvent, stirring evenly, and then freezing, microwave heating and drying, to obtain a chlorinated polyvinyl chloride resin with a loose resin particle structure, a high plasticizer absorption rate, and a large specific surface area. Summary of the invention

[0006] To this end, the technical problem to be solved by the present invention is to provide a polyvinyl chloride resin for gas-solid phase chlorination, which has the advantages of thin particle film, low coverage, loose resin particles, many internal pores, uniform structure, and fast plasticizer absorption rate, and is suitable for the chlorination production process of CPVC resin for gas-solid phase method;

[0007] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned polyvinyl chloride resin specially used for gas-solid phase chlorination, which effectively solves the problem that traditional suspension polyvinyl chloride resin cannot meet the requirements of gas-solid phase chlorination process.

[0008] In order to solve the above technical problems, the present invention provides a method for preparing a polyvinyl chloride resin for chlorination by a gas-solid phase method, comprising the following steps:

[0009] (1) taking an initiator and a dispersant, adding deionized water to mix, evacuating the mixture, and adding vinyl chloride monomer to carry out a polymerization reaction;

[0010] (2) adding an antistatic agent to the polymer reactant to continue the reaction;

[0011] (3) adding a terminator to the above-mentioned polymerization reaction product to terminate the reaction, and collecting the reaction product to obtain the product.

[0012] Specifically, the preparation method of the polyvinyl chloride resin for chlorination by the gas-solid phase method comprises the following raw material proportions:

[0013]

[0014] Specifically, in the preparation method of the gas-solid phase method for preparing the special chlorinated polyvinyl chloride resin, the dispersant comprises a mixture of a polyvinyl alcohol dispersant with a high degree of polymerization and a high alcoholysis degree and a polyvinyl alcohol dispersant with a low degree of polymerization and a low alcoholysis degree. The dispersant is a polyvinyl alcohol multi-component composite dispersant with high and low degrees of polymerization and alcoholysis, such as high degree of polymerization and high alcoholysis degree KH-20 with high adhesive retention and polymerization stability, POVAL L series products with relatively low degree of polymerization and alcoholysis degree, and POVAL LM series products with low degree of polymerization and low alcoholysis degree with high surface activity, and the dispersant adopts three or more composite systems.

[0015] Specifically, in the preparation method of the gas-solid phase method for chlorinated polyvinyl chloride resin, the initiator includes a composite initiator system with high, medium and low activity. The initiator is generally selected from an initiator with a half-life of preferably 2-3h at the polymerization temperature, and a composite initiator system with high, medium and low activity can be used. Azo and peroxide initiators can be selected, such as azobisisoheptanenitrile, bis-2-ethylhexyl peroxydicarbonate (EHP), tert-amyl peroxy pivalate (TAPP), tert-butyl peroxy neodecanoate (Tx23) and tert-hexyl peroxy pivalate (PV70). Two or more of them can be selected.

[0016] Preferably, the initiator comprises a mixture of a high-activity initiator and a low-activity initiator;

[0017] Preferably, the mass ratio of the high-activity initiator to the low-activity initiator is 2:1.

[0018] Specifically, in the preparation method of the gas-solid phase method for preparing a special polyvinyl chloride resin for chlorination, the antistatic agent includes one or a mixture of polymer permanent antistatic agent, polyether antistatic agent or quaternary ammonium salt antistatic agent. For example, ethylene oxide-epichlorohydrin copolymer and (meth) acrylate copolymer containing quaternary ammonium salt can be selected. When used, the antistatic agent can be dissolved in water to form a uniform solution, and the content of the antistatic agent is 50%-60%.

[0019] Specifically, in the preparation method of the gas-solid phase method for preparing a special polyvinyl chloride resin for chlorination, the terminator includes one or a mixture of polyphenol compounds, aromatic amine compounds, nitro compounds, organic sulfur compounds or inorganic compounds. The terminator can terminate the polymerization reaction of vinyl chloride and improve the whiteness of the resin, such as the terminator bisphenol A, acetone thiosemicarbazone (ATSC), diethylhydroxylamine (DEHA).

[0020] Specifically, the preparation method of the polyvinyl chloride resin for chlorination by the gas-solid phase method is as follows:

[0021] In the step (1), in the vacuuming step, the vacuum degree is controlled to be 0.1 MPa; and / or,

[0022] In the step (1), the polymerization reaction temperature is 55-65° C.; and / or,

[0023] In the step (3), the temperature of the stripping step is 80-110°C.

[0024] The invention also discloses a polyvinyl chloride resin specially used for gas-solid phase chlorination prepared by the method.

[0025] The invention also discloses the use of the gas-solid phase method chlorinated special polyvinyl chloride resin in preparing chlorinated polyvinyl chloride (CPVC) resin.

[0026] The invention also discloses chlorinated polyvinyl chloride (CPVC) resin prepared from the polyvinyl chloride resin.

[0027] The method for preparing a special polyvinyl chloride resin for chlorination by a gas-solid phase method of the present invention adopts a multi-component high-low polymerization degree and alcoholysis degree polyvinyl alcohol composite dispersion system based on a traditional polyvinyl chloride resin synthesis process, and adds an antistatic agent in the initial polymerization stage. The antistatic agent can be adsorbed and grafted on the surface of resin particles and distributed inside the particles, so as to prepare a special polyvinyl chloride resin with a special particle structure, and effectively avoids the defect of the traditional PVC resin that the antistatic agent remains on the resin surface.

[0028] The polyvinyl chloride resin specially used for gas-solid phase chlorination of the present invention has the advantages of thin particle film, low coverage, loose resin particles, multiple internal pores, uniform structure, and fast plasticizer absorption rate; and the PVC resin particles have unique particle structure characteristics such as good regularity, uniform particle size distribution, good fluidity, etc., and are suitable for the chlorination production process of CPVC resin used in the gas-solid phase method.

[0029] The gas-solid phase method chlorinated special polyvinyl chloride resin of the present invention is mainly used for chlorination modification to produce CPVC resin. The CPVC resin has the characteristics of heat resistance, flame retardancy, chemical medium corrosion resistance and high mechanical strength, and has a wide range of applications. It has obvious advantages in application fields such as pipes and pipe fittings for hot and cold water, fire fighting pipes, heat-resistant and corrosion-resistant pipes / pipe fittings for chemical industry, casings for buried high-voltage power cables, and pipes for crude oil gathering and transportation in oil fields. It is a new type of engineering plastic with a rapid development speed and broad market prospects in recent years. The domestic production capacity of CPVC resin has approached 200,000 tons / year, and the chlorinated PVC special resin has huge market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 and Figure 2 This is an electron microscope photo of typical particles of the resin in Comparative Example 2;

[0032] Figure 3 and Figure 4 This is a typical electron microscope photograph of the resin particles in Example 4 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention.

[0034] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereto.

[0035] Examples 1-4

[0036] The raw material selection and proportion of the polyvinyl chloride resin for gas-solid phase chlorination described in the following Examples 1-4 of the present invention are shown in Table 1 below.

[0037] The method for preparing the polyvinyl chloride resin for chlorination by gas-solid phase method described in the following embodiments 1-4 of the present invention comprises the following steps:

[0038] (1) Clean and rinse the polymerization kettle, apply an anti-sticking agent, add deionized water, initiator and dispersant in the formula according to the ratio in Table 1 below, mix, then evacuate to a certain vacuum degree (about 0.1 MPa), add a selected amount of vinyl chloride monomer and mix; cold stir for 10 minutes, then heat to 55-65° C. (see Table 1 for details) to carry out polymerization reaction, and start timing;

[0039] (2) After the real-time monitoring polymerization conversion rate reaches 15%, a selected amount of antistatic agent is added and mixed, and the polymerization reaction is continued;

[0040] (3) After the pressure of the polymerization kettle drops to the process control point (generally the polymerization pressure is controlled to drop by 0.10-0.15 GPma), add a selected amount of terminator and mix; after continuing to stir for 15 minutes, recover the monomer, discharge the slurry, perform gas stripping at 90°C, and continue drying for 2 hours to obtain a chlorinated PVC special resin.

[0041] Comparative Examples 1-4

[0042] The raw material selection and proportion of the polyvinyl chloride resin described in the following comparative examples 1-4 of the present invention are shown in Table 1 below.

[0043] The preparation method of the polyvinyl chloride resin described in the following comparative examples 1-4 of the present invention is the same as that of the aforementioned embodiments 1-4.

[0044] Table 1 Polymerization formula of Examples 1-4 and Comparative Examples 1-4 (parts by weight)

[0045]

[0046] Experimental example

[0047] The properties of the resins produced in the above Examples 1-4 and Comparative Examples 1-4 were tested respectively, and the test results are shown in Table 2 below.

[0048] The plasticizer absorption time is measured by a Brabender star mixer, and the process conditions are as follows: temperature 90°C, rotation speed 100r / min; 10g of organotin stabilizer is added to 500g of resin, stirred evenly, put into the mixer, mixed for 5min, and 250g of plasticizer is added until the plasticizer is completely absorbed. The time from the addition of the plasticizer to the complete absorption is the plasticizer absorption time.

[0049] Table 2 Resin performance test results

[0050]

[0051] Among them, the electron microscope photo of the typical particles of the resin prepared in Comparative Example 2 is attached Figure 1-2 The electron microscope photo of the typical particles of the resin prepared in Example 2 of the present invention is attached. Figure 3-4 .

[0052] It can be seen that the polyvinyl chloride resin specially used for chlorination by the gas-solid phase method of the present invention has the advantages of thin particle film, low coverage, loose resin particles, many internal pores, uniform structure, and fast plasticizer absorption rate; and the PVC resin particles have good regularity, uniform particle size distribution, good fluidity and other unique particle structure characteristics, which is suitable for the chlorination production process of CPVC resin by the gas-solid phase method.

[0053] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a polyvinyl chloride resin for chlorination by a gas-solid phase method, characterized in that: The steps include: (1) taking an initiator and a dispersant, adding deionized water to mix, evacuating the mixture, and adding vinyl chloride monomer to carry out a polymerization reaction; (2) adding an antistatic agent to the polymer reactant to continue the reaction; (3) adding a terminator to the above-mentioned polymerization reaction product to terminate the reaction, and collecting the reaction product to obtain the product.

2. The method for preparing polyvinyl chloride resin for chlorination by gas-solid phase method according to claim 1, characterized in that: The proportion of each raw material includes: Deionized water 120-140 parts by weight; Initiator 0.01-0.20 parts by weight; Dispersion system 0.03-0.40 parts by weight; 100 parts by weight of vinyl chloride monomer; 1-5 parts by weight of antistatic agent; Terminator 0.01-0.10 parts by weight.

3. The method for preparing a polyvinyl chloride resin for chlorination by a gas-solid phase method according to claim 1 or 2, characterized in that: The dispersant comprises a mixture of a polyvinyl alcohol dispersant with a high degree of polymerization and a high degree of alcoholysis and a polyvinyl alcohol dispersant with a low degree of polymerization and a low degree of alcoholysis.

4. The method for preparing a polyvinyl chloride resin for chlorination by a gas-solid phase method according to claim 1 or 2, characterized in that: The initiator includes a composite initiator system with high, medium and low activity; Preferably, the initiator comprises a mixture of a high-activity initiator and a low-activity initiator; Preferably, the mass ratio of the high-activity initiator to the low-activity initiator is 2:

1.

5. The method for preparing a polyvinyl chloride resin for chlorination by a gas-solid phase method according to claim 1 or 2, characterized in that: The antistatic agent includes one or a mixture of polymer permanent antistatic agent, polyether antistatic agent or quaternary ammonium salt antistatic agent.

6. The method for preparing a polyvinyl chloride resin for chlorination by a gas-solid phase method according to claim 1 or 2, characterized in that: The terminator includes one or a mixture of polyphenol compounds, aromatic amine compounds, nitro compounds, organic sulfur compounds or inorganic compounds.

7. The method for preparing a polyvinyl chloride resin for chlorination by a gas-solid phase method according to any one of claims 1 to 6, characterized in that: In the step (1), in the vacuuming step, the vacuum degree is controlled to be 0.1 MPa; and / or, In the step (1), the polymerization reaction temperature is 55-65° C.; and / or, In the step (3), the temperature of the stripping step is 80-110°C.

8. A polyvinyl chloride resin specially prepared by the method according to any one of claims 1 to 7 for chlorination by a gas-solid phase process.

9. Use of the polyvinyl chloride resin specially prepared for gas-solid phase chlorination according to claim 8 for preparing chlorinated polyvinyl chloride (CPVC) resin.

10. Chlorinated polyvinyl chloride (CPVC) resin prepared from the polyvinyl chloride resin according to claim 8.

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