A method for preparing a radiation resistant PVC resin

Abstract

The application relates to a preparation method of a radiation-resistant PVC resin and belongs to the technical field of grafted polymer compositions. The existing radiation-resistant modification method of the PVC resin has low radiation-resistant modification effect or seriously affects the mechanical properties of the PVC resin. The method is as follows: 1) uniformly dispersing an initiator, a dispersing agent, a radiation-resistant agent and a chain transfer agent in water; 2) vacuumizing and adding a vinyl chloride monomer, uniformly stirring at normal temperature and heating and reacting; 3) uniformly stirring after adding a terminating agent and drying to obtain the PVC resin; wherein the radiation-resistant agent in the step 1) is a solution of p-methoxy cinnamoyloxy propyl trimethoxysilane and 4-methyl-acrylate-2-hydroxy benzophenone in any proportion. The radiation-resistant component is combined into the PVC resin particles, and the radiation-resistant capacity is improved from the essence of the particles. The selected specific radiation-resistant agent component can be well combined with the PVC resin, and does not affect or even improves the mechanical properties.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a radiation-resistant PVC resin and belongs to the technical field of grafted polymer compositions. BACKGROUND

[0002] Traditional medical instrument ethylene oxide sterilization has the defect of ethylene oxide residue, which has adverse effects on human health and the atmosphere. High-energy ray irradiation disinfection is efficient, safe, and free of chemical residues, but PVC resin after irradiation has the adverse phenomena of large yellowing and mechanical property reduction, which cannot meet the use requirements, so it is particularly important to develop a new radiation-resistant PVC material.

[0003] An application patent CN103435725B discloses a water emulsion type PVC resin terminator, which is prepared by the following steps: firstly, the stabilizer and the phenolic antioxidant are dissolved and stirred, and then the temperature is kept constant and then lowered to room temperature; then, the light stabilizer and the polymerization inhibitor are added and stirred uniformly to obtain a mixed terminator solution; then, the emulsifier is added to the mixed terminator solution, and the temperature is raised and stirred uniformly to obtain a mixed emulsion, and meanwhile, the dispersant and water are mixed and stirred to obtain a dispersion solution; finally, the dispersion solution is added to the mixed emulsion to obtain the water emulsion type PVC resin terminator. The light stabilizer is mixed with the polymerization inhibitor, that is, the light stabilizer is used in the method after the PVC resin polymerization is completed, and is mixed with the polymerization inhibitor to enter the PVC resin chain of the formed PVC resin. Since the light stabilizer and the PVC resin are different in nature and poor in compatibility, the mechanical properties of the final PVC resin product are easily reduced.

[0004] An application patent CN102051006B discloses a radiation-resistant high-resilience PVC composition and a preparation method thereof. The radiation-resistant high-resilience PVC composition is prepared by blending and processing the PVC resin, the plasticizer and the powder nitrile rubber, and then melting and blending.

[0005] An application patent CN114685925A discloses a radiation-resistant rigid PVC material and a preparation method and application thereof. The material is prepared by using a grafting modified PVC powder and a processing formula composed of various stabilizers. The stabilizers are an organic tin stabilizer and an auxiliary stabilizer of epoxy soybean oil, but according to the common knowledge of those skilled in the art, the organic tin stabilizer is difficult to be grafted into the long chain of the PVC resin well, and therefore, the mechanical properties of the resin are affected. Moreover, the principle is to improve the thermal stability of the PVC resin to reduce the yellowing and mechanical property reduction of the resin, and the yellowing problem caused by irradiation cannot be well relieved. SUMMARY

[0006] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide a preparation method of a radiation-resistant PVC resin capable of improving the radiation resistance of the PVC resin while avoiding the reduction of mechanical properties.

[0007] The technical solution adopted by the present application to solve its technical problem is a preparation method of a radiation-resistant PVC resin, characterized by comprising the following steps:

[0008] 1) uniformly dispersing an initiator, a dispersant, a radiation-resistant agent and a chain transfer agent in water;

[0009] 2) vacuumizing to -0.9~-0.5MPa, adding a vinyl chloride monomer, uniformly stirring at room temperature, heating to 55~65℃, and reacting until the pressure is 0.2~0.3MPa;

[0010] 3) adding a terminating agent, uniformly stirring, and drying to obtain a PVC resin;

[0011] In step 1), the radiation-resistant agent is a solution of p-methoxycinnamoyloxypropyltrimethoxysilane and 4-methyl-acrylate-2-hydroxybenzophenone in any proportion.

[0012] In the process of polymerization of the vinyl chloride monomer into macro-level (10μm or more), the radiation-resistant component is combined into the interior of the PVC resin particles, thus improving the radiation resistance of the PVC resin from the nature of the particles. The selected specific radiation-resistant agent component can be well combined with the PVC resin and connected to the molecular chain of the PVC resin at a micro-level, thus improving the radiation resistance of the PVC while not affecting or even improving the mechanical properties.

[0013] Preferably, the weight ratio of p-methoxycinnamoyloxypropyltrimethoxysilane to 4-methyl-acrylate-2-hydroxybenzophenone in the radiation-resistant agent is 1:1~2.

[0014] Preferably, the preparation method of the radiation-resistant agent is as follows: p-methoxycinnamoyloxypropyltrimethoxysilane and 4-methyl-acrylate-2-hydroxybenzophenone are mixed in a weight ratio of 1:1~2 in ethyl acetate to obtain a preliminary dispersion liquid, sorbitan monooleate and sodium dodecylbenzenesulfonate are added, and uniformly stirred to obtain the radiation-resistant agent. Further preferably, the total weight of p-methoxycinnamoyloxypropyltrimethoxysilane and 4-methyl-acrylate-2-hydroxybenzophenone is in a ratio of 1:10 to the total weight of ethyl acetate.

[0015] The dispersion of the two radiation-resistant agent components using a specific method can effectively promote the combination of the radiation-resistant agent components with the PVC resin, realize the addition of the radiation-resistant components from the macro-level and the micro-level, improve the radiation resistance effect while further reducing the impact on the mechanical properties.

[0016] Further preferably, the weight ratio of the preliminary dispersion liquid to sorbitan monooleate and sodium dodecylbenzenesulfonate is 1:1 to 5:1 to 5.

[0017] Further preferably, the uniform stirring is performed using a high-speed sand mill with a rotation speed of 5000 to 6000 rpm.

[0018] Preferably, the amount of each raw material is as follows: 100 parts of vinyl chloride monomer, 100 to 300 parts of deionized water, 0.005 to 0.2 parts of initiator, 0.005 to 0.2 parts of dispersant, 0.001 to 0.3 parts of radiation-resistant agent, and 0.01 to 0.05 parts of chain transfer agent.

[0019] Further preferably, 0.001 to 0.3 parts of a terminator is further included.

[0020] Preferably, the initiator is a mixture of t-amyl peroxyneodecanoate (TAPP) and t-butyl peroxyneodecanoate (TBPND) at a weight ratio of 1:1 to 2, or a mixture of di(2-ethylhexyl) peroxydicarbonate (EHP) and cumyl peroxyneodecanoate (ACPND) at a weight ratio of 1:1 to 2.

[0021] Further preferably, the chain transfer agent is diethylhydroxylamine, and the terminator is acetone thiosemicarbazone or diethylhydroxylamine single terminator, or the terminator is a composite heat-resistant terminator composed of dilauryl thiodipropionate and hindered phenolic antioxidant.

[0022] Preferably, the dispersant is a mixture of hydroxypropyl methylcellulose E50, polyethylene PVA80, and polyethylene PVA55 at a weight ratio of 1:0.2 to 1:0.1 to 0.5.

[0023] Preferably, the drying is performed at 50 to 100°C for 2 to 6 hours under vacuum.

[0024] Compared with the prior art, the present application has the beneficial effect that the granulation of the suspended PVC resin includes macro-granulation and sub-micro and micro-granulation, and the structure of the resin powder formed accordingly includes VCM monomer droplets or particles of macro-level (10 microns or above) formed by coalescence, and various particles of micro-level (0.1 micron or below) and sub-micro level (0.1-10 microns) formed inside the VCM monomer. The two-level structure determines the final particle characteristics of the PVC resin powder, which has a huge impact on the quality of the PVC product, the plasticizing processing performance and the use performance of the product, which are closely related to the formula and process of the PVC suspension polymerization. The radiation resistant agent in the present application is combined into the PVC resin particle when the VCM monomer droplets or particles coalesce to form particles, thereby improving the radiation resistance from the nature of the particles, while not affecting or even improving the mechanical properties. The p-methoxycinnamoyloxypropyltrimethoxysilane and 4-methyl-acrylate-2-hydroxybenzophenone in the radiation resistant agent can convert light energy into heat energy by using their own molecular structure, avoiding the light oxidation reaction of the material directly absorbing light energy, thereby improving the light stability of the PVC resin, and further delaying the yellowing and mechanical property decline of the PVC resin when it receives radiation. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with the examples, and Example 1 is the best embodiment of the present application.

[0026] Example 1

[0027] A method for preparing a radiation resistant PVC resin, comprising the following steps:

[0028] 1) Dissolve 0.005 kg of p-methoxycinnamoyloxypropyltrimethoxysilane and 0.005 kg of 4-methyl-acrylate-2-hydroxybenzophenone in 0.05 kg of ethyl acetate, stir to obtain a preliminary dispersion, then add 0.05 kg of sorbitan monooleate, 0.05 kg of sodium dodecylbenzenesulfonate, and stir with a high-speed sand mill at a speed of 5500 rpm until uniform and not stratified to obtain a radiation resistant agent.

[0029] 2) Add 140 kg of deionized water, 0.02 kg of initiator ACPND, 0.03 kg of initiator EHP, 0.02 kg of dispersant E500, 0.01 kg of dispersant PVA80, 0.006 kg of dispersant PVA55, 0.02 kg of radiation resistant agent, and 0.02 kg of chain transfer agent diethylhydroxylamine to the reaction kettle.

[0030] 3) The reactor is vacuumed to -0.09 MPa, 100 kg of vinyl chloride monomer is added, stirred at 470 rpm for 8 min, heated to 60.5℃, and reacted until the pressure is 0.3 MPa.

[0031] 4) 0.03 kg of the terminator acetone thiosemicarbazone is added, stirred for 5 min, dehydrated at 3000 rpm, and vacuum dried at 75℃, -0.1 MPa for 6 h to obtain the radiation-resistant PVC resin.

[0032] Example 2

[0033] A method for preparing a radiation-resistant PVC resin, based on Example 1, the weight of p-methoxycinnamoyloxypropyltrimethoxysilane and 4-methyl-acrylate-2-hydroxybenzophenone in step 1) is set to 0.004 kg and 0.006 kg respectively. Other conditions are the same as in Example 1.

[0034] Example 3

[0035] A method for preparing a radiation-resistant PVC resin, based on Example 1, the dosage of the radiation-resistant agent in step 2) is set to 0.03 kg, and other conditions are the same as in Example 1.

[0036] Example 4

[0037] A method for preparing a radiation-resistant PVC resin, based on Example 1, the dosage of the radiation-resistant agent in step 2) is set to 0.001 kg, and other conditions are the same as in Example 1.

[0038] Comparative Example 1

[0039] A method for preparing a radiation-resistant PVC resin, based on Example 1, no radiation-resistant agent is added in step 2), and other conditions are the same as in Example 1.

[0040] Comparative Example 2

[0041] A method for preparing a radiation-resistant PVC resin, based on Example 1, the dosage of p-methoxycinnamoyloxypropyltrimethoxysilane in step 1) is set to 0.01 kg, and no 4-methyl-acrylate-2-hydroxybenzophenone is added, and other conditions are the same as in Example 1.

[0042] Comparative Example 3

[0043] A method for preparing a radiation-resistant PVC resin, based on Example 1, the dosage of 4-methyl-acrylate-2-hydroxybenzophenone in step 1) is set to 0.01 kg, and no p-methoxycinnamoyloxypropyltrimethoxysilane is added, and other conditions are the same as in Example 1.

[0044] Comparative Example 4

[0045] A method for preparing a radiation-resistant PVC resin, based on Example 1, in step 2) no radiation-resistant agent is added, but a radiation-resistant agent is added before the termination agent in step 4), and after stirring for 8 min, the termination agent is added. Other conditions are the same as in Example 1.

[0046] Performance test

[0047] The PVC resins obtained in the above examples and comparative examples were respectively added to an equal amount of DOP, epoxy soybean oil, phosphite, antioxidant, stabilizer, lubricant, to make 2mm thick square pieces, and after irradiation of the PVC transparent square pieces with 25kGy high energy rays for one week in a simulated radiation sterilization scene, the yellow index and mechanical property test results before irradiation are shown in Table 1.

[0048] The yellow index performance test method is tested according to HG / T 3862-2006.

[0049] The tensile strength and elongation at break performance test method is tested according to GB / T 1040.1-2018, using type V sample, and the tensile speed is 50mm / min.

[0050] Table 1 Test results before irradiation

[0051] .

[0052] The yellow index and mechanical property test results after irradiation are shown in Table 2.

[0053] Table 2 Test results after irradiation

[0054] .

[0055] The results show that the radiation-resistant additive solution can effectively delay the yellowing degree of PVC resin after 25kGy irradiation, especially the two reagents in Example 1 are used together to play a synergistic effect, the yellow index after irradiation is the lowest, and the tensile strength and elongation at break are also obviously improved. Compared with the comparative example, the yellow index of the PVC product after irradiation can be reduced by 5~7 after adding the radiation-resistant additive solution, and the preferred amount of radiation-resistant additive solution added is 0.02 parts by weight.

[0056] The above is only a preferred embodiment of the present application, and is not intended to limit the other forms of the present application, and any skilled person in the art can use the disclosed technical content to make changes or modifications to equivalent embodiments. However, any simple modification, equivalent change and modification made to the above examples according to the technical essence of the present application without departing from the technical solution content of the present application, still belongs to the protection scope of the technical solution of the present application.

Claims

1. A method for the production of a radiation resistant PVC resin, characterized by: It comprises the following steps: 1) uniformly dispersing initiator, dispersant, radiation resistant agent and chain transfer agent in water; 2) vacuumizing to -0.09 MPa, adding vinyl chloride monomer, uniformly stirring at normal temperature, heating to 55-65℃, and reacting until the pressure is 0.2-0.3 MPa; 3) adding terminating agent, uniformly stirring, and drying to obtain PVC resin; The radiation resistant agent in step 1) is a solution of p-methoxycinnamoyloxypropyltrimethoxysilane and 4-methyl-acrylate-2-hydroxybenzophenone mixed in any ratio; The weight ratio of p-methoxycinnamoyloxypropyltrimethoxysilane and 4-methyl-acrylate-2-hydroxybenzophenone in the radiation resistant agent is 1:1-2.

2. The method of making a radiation resistant PVC resin according to claim 1, characterized in that: The preparation method of the radiation resistant agent is: mixing p-methoxycinnamoyloxypropyltrimethoxysilane and 4-methyl-acrylate-2-hydroxybenzophenone to obtain a preliminary dispersion solution in ethyl acetate, adding sorbitan monooleate and sodium dodecylbenzenesulfonate, uniformly stirring, and obtaining the radiation resistant agent.

3. The method of making a radiation resistant PVC resin according to claim 2, characterized in that: The weight ratio of the preliminary dispersion solution, sorbitan monooleate and sodium dodecylbenzenesulfonate is 1:1-5:1-5.

4. The method of making a radiation resistant PVC resin according to claim 2, characterized in that: The uniformly stirring is performed by a high-speed sand mill at a speed of 5000-6000 rpm.

5. The method of making a radiation resistant PVC resin according to claim 1, characterized in that: The amount of each raw material is in parts by weight: 100 parts of vinyl chloride monomer, 100-300 parts of deionized water, 0.005-0.2 parts of initiator, 0.005-0.2 parts of dispersant, 0.001-0.3 parts of radiation resistant agent, and 0.01-0.05 parts of chain transfer agent.

6. The method of making a radiation resistant PVC resin according to claim 5, wherein: It also includes 0.001-0.3 parts of terminating agent.

7. The method of making a radiation resistant PVC resin according to claim 1, wherein: The initiator is a mixture of t-amyl peroxypivalate and t-butyl peroxyneodecanoate at a weight ratio of 1:1-2; or a mixture of di(2-ethylhexyl) peroxydicarbonate and cumyl peroxyneodecanoate at a weight ratio of 1:1-2.

8. The method of making a radiation resistant PVC resin according to claim 1, wherein: The dispersant is a mixture of hydroxypropyl methylcellulose E50, polyethylene PVA80 and polyethylene PVA55 at a weight ratio of 1:0.2-1:0.1-0.

5.

9. The method of making a radiation resistant PVC resin according to claim 1, wherein: The drying is performed at 50-100℃ for 2-6h under vacuum.