Special polyvinyl chloride resin for gas-solid phase chlorination and preparation method and application thereof

Abstract

The application belongs to the technical field of polymer chemical raw materials and resin synthesis, and particularly relates to a polyvinyl chloride resin (PVC), more particularly relates to a special polyvinyl chloride resin for gas-solid phase chlorination, and further discloses a preparation method thereof. The preparation method of the special polyvinyl chloride resin for gas-solid phase chlorination, on the basis of a traditional polyvinyl chloride resin synthesis process, adopts a polyvinyl alcohol composite dispersion system with multiple high and low polymerization degrees and alcoholysis degrees, and a polymerization mode of adding an antistatic agent in the initial stage of polymerization, the antistatic agent can be adsorbed and grafted on the surface of resin particles and distributed in the interior of the particles, and a special polyvinyl chloride resin with a special particle structure is prepared.

Description

Technical Field

[0001] This invention belongs to the field of polymer chemical raw materials and resin synthesis technology, specifically relating to a polyvinyl chloride resin (PVC), and more specifically to a gas-solid phase chlorination-specific polyvinyl chloride resin, and further discloses its preparation method. Background Technology

[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 significant improvements in heat resistance, flame retardancy, chemical corrosion resistance, and mechanical strength. CPVC resin has a wide range of applications, showing clear advantages in hot and cold water pipes and fittings, fire protection pipes, high-temperature and corrosion-resistant pipes / fittings for chemical applications, underground high-voltage power cable conduits, and oilfield crude oil gathering and transportation pipes. It is a rapidly developing new engineering plastic with broad market prospects in recent years.

[0003] The performance of PVC resin, the raw material for CPVC production, is the main factor directly affecting the quality of CPVC resin. Based on the performance requirements of CPVC resin, a special PVC particle structure needs to be constructed, possessing characteristics such as thin particle film, low coverage, loose resin particles, numerous internal pores, uniform structure, fast plasticizer absorption rate, good particle regularity, and uniform particle size distribution.

[0004] Currently, the main production methods for CPVC resin in China are aqueous suspension and gas-solid phase methods. Aqueous suspension technology is mature and has reached a large scale, while the gas-solid phase chlorination process, due to its advantages such as no need for a dispersion medium, direct chlorination in a reactor or fluidized bed, shorter production process, less environmental pollution, and virtually no emissions of waste gas, wastewater, and solid waste, is more in line with the trend of clean and environmentally friendly development. However, while the gas-solid phase process has the advantages of being clean and environmentally friendly, its reaction process is difficult to control, resulting in slow chlorination reactions, poor product uniformity, and high technical difficulty. It is necessary to solve problems related to controlling the flowability of materials, heat transfer during the chlorination reaction, and the uniformity of product chlorination. Therefore, the gas-solid phase process places higher demands on the particle morphology, average particle size, flowability, and chlorination performance of PVC resin. Currently, domestic gas-solid phase CPVC production processes all adopt technology from the French company ARKEMA, using bulk PVC chlorination-specific resin as raw material. Suspension PVC resin, due to factors such as flowability and particle structure, cannot meet the requirements of the gas-solid phase chlorination process.

[0005] For example, Chinese patent CN104277169A discloses a method for producing chlorinated polyvinyl chloride (PVC) resin. By adding regulators and dispersants twice during the polymerization process, a chlorinated PVC resin with a loose structure, high porosity, high oil absorption, and a thin surface film is produced. Another example is Chinese patent CN108192001B, which discloses a method for producing chlorinated PVC resin. This method involves premixing a quality agent and VCM monomer evenly before polymerization. The quality agent is a polyvinyl alcohol with a low degree of polymerization and low degree of alcoholysis. The resulting chlorinated PVC resin has regular particle morphology, a loose structure, uniform pore distribution, and high particle size concentration. Furthermore, Chinese patent CN112029138A discloses a method for preparing chlorinated PVC resin. This involves taking centrifuged, water-containing PVC resin, adding a functional organic solvent, stirring evenly, then freezing and drying with microwave heating to obtain a chlorinated PVC resin with a loose particle structure, high plasticizer absorption rate, and large specific surface area. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide a special polyvinyl chloride resin for gas-solid phase chlorination. The polyvinyl chloride resin 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 in gas-solid phase process.

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

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

[0009] (1) Take the initiator and dispersant, add them to deionized water and mix. After vacuuming, add vinyl chloride monomer to carry out the polymerization reaction.

[0010] (2) Add an antistatic agent to the polymerization reactants and continue the reaction;

[0011] (3) Add a terminator to the above polymerization reactants to terminate the reaction, collect the reactants, and obtain the product.

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

[0013]

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

[0015] Specifically, in the preparation method of the gas-solid phase chlorination-specific polyvinyl chloride resin, the initiator includes a composite initiator system with high, medium, and low activity. The initiator is generally selected with a half-life of preferably 2-3 hours at the polymerization temperature. A composite initiator system with high, medium, and low activity can be used, and azo or peroxide initiators can be selected, such as two or more of azobisisoheptanenitrile, bis-2-ethylhexyl peroxydicarbonate (EHP), tert-amyl peroxypentanoate (TAPP), tert-butyl peroxyneodecanate (Tx23), and tert-hexyl peroxypentanoate (PV70).

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

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

[0018] Specifically, in the preparation method of the gas-solid phase chlorination-specific polyvinyl chloride resin, the antistatic agent includes one or a mixture of several of the following: a polymeric permanent antistatic agent, a polyether-based antistatic agent, or a quaternary ammonium salt-based antistatic agent. For example, ethylene oxide-epoxychloropropane copolymers or (meth)acrylate copolymers containing quaternary ammonium salts can be selected. In use, the antistatic agent can be dissolved in water to form a homogeneous solution, with the antistatic agent content being 50%-60%.

[0019] Specifically, in the gas-solid phase chlorination method for preparing the special polyvinyl chloride resin, the terminator includes one or a mixture of several of the following: polyphenolic 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; for example, bisphenol A, acetone thiourea (ATSC), and diethylhydroxylamine (DEHA) can be selected as terminators.

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

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

[0022] In step (1), the polymerization reaction is carried out at a temperature of 55-65°C; and / or,

[0023] In step (3), the temperature of the air-lift step is 80-110℃.

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

[0025] The present invention also discloses the use of the gas-solid phase chlorination-specific polyvinyl chloride resin for the preparation of chlorinated polyvinyl chloride (CPVC) resin.

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

[0027] The gas-solid phase method for preparing chlorinated polyvinyl chloride resin of the present invention, based on the traditional polyvinyl chloride resin synthesis process, adopts a multi-element polyvinyl alcohol composite dispersion system with high and low degree of polymerization and degree of alcoholysis, and by adding an antistatic agent in the early stage of polymerization, the antistatic agent can be adsorbed and grafted onto the surface of the resin particles and distributed inside the particles, thus preparing a special polyvinyl chloride resin with a special particle structure, effectively avoiding the defect of antistatic agent residue on the resin surface in traditional PVC resin.

[0028] The gas-solid phase chlorination-specific polyvinyl chloride resin of this invention has the advantages of thin particle film, low coverage, loose resin particles, many internal pores, and uniform structure, and fast plasticizer absorption rate; in addition, the PVC resin particles have good regularity, uniform particle size distribution, and good flowability, which are unique particle structure characteristics suitable for the gas-solid phase chlorination production process of CPVC resin.

[0029] The gas-solid phase chlorination-specific polyvinyl chloride resin described in this invention is mainly used for the chlorination modification production of CPVC resin. CPVC resin has the characteristics of heat resistance, flame retardancy, chemical corrosion resistance and high mechanical strength, and has a wide range of applications. It has obvious advantages in applications such as hot and cold water pipes and fittings, fire protection pipes, temperature and corrosion resistant pipes / fittings for chemical industry, buried high-voltage power cable sleeves, and oilfield crude oil gathering and transportation pipes. It is a new type of engineering plastic with rapid development and broad market prospects in recent years. The domestic production capacity of CPVC resin has reached nearly 200,000 tons / year, and there is huge market potential for chlorinated PVC-specific resin. Attached Figure Description

[0030] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0031] Figure 1 and Figure 2 Here are typical electron micrographs of the resin particles in Comparative Example 2;

[0032] Figure 3 and Figure 4 This is a typical electron microscope image of the resin particles in Example 4 of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0034] The present invention will be further described below with reference to the embodiments, but this does not limit the present invention.

[0035] Examples 1-4

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

[0037] The preparation method of the gas-solid phase chlorination-specific polyvinyl chloride resin described in Examples 1-4 of this invention includes the following steps:

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

[0039] (2) After the polymerization conversion rate reaches 15% as monitored in real time, add the selected amount of antistatic agent and mix, and continue the polymerization reaction;

[0040] (3) After the pressure in the polymerization reactor drops to the process control point (generally the polymerization pressure drop is controlled to be 0.10-0.15GPma), add the selected amount of terminator and mix; continue stirring for 15 minutes, recover the monomer, discharge the slurry, perform air stripping at 90℃, and continue drying for 2 hours to obtain chlorinated PVC special resin.

[0041] Comparative Examples 1-4

[0042] The selection and proportioning of raw materials for the polyvinyl chloride resin described in Comparative Examples 1-4 of this invention are shown in Table 1 below.

[0043] The preparation methods of the polyvinyl chloride resin described in the following comparative examples 1-4 are the same as those in the aforementioned examples 1-4.

[0044] Table 1. Polymerization formulations (parts by weight) for Examples 1-4 and Comparative Examples 1-4

[0045]

[0046] Experimental Example

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

[0048] The plasticizer absorption time was determined using a Brabender star mixer under the following conditions: temperature 90℃, rotation speed 100r / min. 10g of organotin stabilizer was added to 500g of resin, stirred evenly, and then added to the mixer. The mixture was stirred for 5 minutes, and then 250g of plasticizer was added until the plasticizer was completely absorbed. The time from the addition of the plasticizer to its complete absorption was defined as the plasticizer absorption time.

[0049] Table 2 Resin Performance Test Results

[0050]

[0051] Typical particle electron micrographs of the resin prepared in Comparative Example 2 are attached. Figure 1-2 Typical particle electron micrographs of the resin prepared in Example 2 of this invention are attached. Figure 3-4 .

[0052] As can be seen, the gas-solid phase chlorination-specific polyvinyl chloride resin of the present invention has the advantages of thin particle film, low coverage, loose resin particles, many internal pores, and uniform structure, and fast plasticizer absorption rate; moreover, the PVC resin particles have good regularity, uniform particle size distribution, and good flowability, which are unique particle structure characteristics suitable for the chlorination production process of CPVC resin in the gas-solid phase method.

[0053] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a gas-solid phase chlorination-specific polyvinyl chloride resin, characterized in that, The steps include the following: (1) Take the initiator and dispersant, add them to deionized water and mix. After vacuuming, add vinyl chloride monomer to carry out the polymerization reaction; (2) After the polymerization conversion rate reaches 15%, an antistatic agent is added to the polymerization reactants to continue the reaction; (3) Add a terminator to the above polymerization reactants to terminate the reaction, collect the reactants, and obtain the product; The proportions of each raw material include: 120-140 parts by weight of deionized water; Initiator 0.01-0.20 parts by weight; Dispersant 0.03-0.40 parts by weight; 100 parts by weight of vinyl chloride monomer; 1.5-5 parts by weight of antistatic agent; Terminator: 0.01-0.10 parts by weight; The dispersant comprises a mixture of polyvinyl alcohol dispersants with high degree of polymerization and high degree of alcoholysis and polyvinyl alcohol dispersants with low degree of polymerization and low degree of alcoholysis; the antistatic agent comprises one or a mixture of polymeric permanent antistatic agents or quaternary ammonium salt antistatic agents; the initiator comprises a mixture of highly active initiators and low-activity initiators; the mass ratio of the highly active initiator to the low-activity initiator is 2:

1.

2. The method for preparing the gas-solid phase chlorination-specific polyvinyl chloride resin according to claim 1, characterized in that, The terminating agent includes one or a mixture of several of the following: polyphenolic compounds, aromatic amine compounds, nitro compounds, organic sulfur compounds, or inorganic compounds.

3. The method for preparing the gas-solid phase chlorination-specific polyvinyl chloride resin according to claim 1 or 2, characterized in that: In step (1), during the vacuuming step, the vacuum level is controlled to be 0.1 MPa; and / or, In step (1), the polymerization reaction is carried out at a temperature of 55-65°C.

4. The method for preparing the gas-solid phase chlorination-specific polyvinyl chloride resin according to claim 1, characterized in that, The antistatic agent is a polyether-based antistatic agent.

5. A gas-solid phase chlorination-specific polyvinyl chloride resin prepared by the method according to any one of claims 1-4.

6. The use of the gas-solid phase chlorination-specific polyvinyl chloride resin of claim 5 for the preparation of chlorinated polyvinyl chloride (CPVC) resin.

7. Chlorinated polyvinyl chloride (CPVC) resin prepared from the polyvinyl chloride resin of claim 5.

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