Antioxidant dispersion liquid for vinyl chloride graft copolymer and use thereof

Abstract

The application relates to an antioxidant dispersion liquid for a vinyl chloride graft copolymer and application thereof, and belongs to the technical field of rubber phase-containing acrylic ester graft vinyl chloride copolymer modification aids. The rubber phase-containing acrylic ester graft vinyl chloride copolymer has the problem of poor thermal stability. At present, the main improvement method for improving the thermal stability of polyvinyl chloride is to add antioxidants, organic tin and other thermal stabilizers in the processing of the vinyl chloride graft copolymer, but the antioxidants will affect the polymerization activity in the rubber phase acrylic ester graft vinyl chloride, and cannot be used in the polymerization process. The antioxidant dispersion liquid is prepared by using antioxidant 245 and a sulfur ester antioxidant in cooperation with a dispersant. The characteristics of the antioxidant 245 and the sulfur ester antioxidant are complementary, the antioxidants are well dispersed in the copolymer, the thermal stability effect is improved, and the antioxidant dispersion liquid is not prone to stratification when standing.

Description

TECHNICAL FIELD

[0001] The application relates to an antioxidant dispersion liquid for a vinyl chloride graft copolymer and application thereof, and belongs to the technical field of rubber phase acrylate graft vinyl chloride copolymer modification aids. BACKGROUND

[0002] Polyvinyl chloride resin (PVC) has excellent flame retardation, chemical corrosion resistance, electrical insulation and other properties, but the thermal stability and impact resistance are poor. As a method for improving the mechanical properties of a vinyl chloride polymer base resin, a process for preparing a graft copolymer by grafting vinyl chloride monomers with rubber phase acrylate polymers having a low glass transition temperature has been developed and used.

[0003] Since the acrylate polymers can realize graft polymerization with vinyl chloride in the polymerization process and are uniformly dispersed in the PVC resin in the polymerization process, the impact strength performance of the product is excellent, the tensile strain is high, and the product shows excellent rigidity and toughness balance, and the mechanical properties are obviously superior to those of the product using an impact resistance modifier.

[0004] However, the graft polymer has the problem of poor thermal stability, and the main improvement method at present is to add antioxidants, organic tin and other thermal stabilizers in the processing of the vinyl chloride graft copolymer, which has limited improvement on the molecular structure defects in the vinyl chloride grafting process. For the graft copolymer obtained by grafting vinyl chloride with rubber phase acrylate latex, the number of unsaturated double bonds not participating in the crosslinking reaction in the copolymer increases due to the introduction of the rubber phase acrylate latex, which has a destructive effect on the thermal stability of the copolymer. For the unsaturated double bond, the main method to improve the thermal stability is to introduce antioxidants, and the phenolic antioxidant has obvious effect. Most of the existing commercial phenolic antioxidants have the effect of eliminating free radicals in the polymer, and can prevent the thermal oxidation of the polymer, so the phenolic antioxidant cannot be used in the polymerization process in most cases, and can only be added after the polymerization is completed. The antioxidant added after the polymerization is completed is often difficult to disperse uniformly in the material, and the thermal stability effect is greatly reduced.

[0005] And with the increase of the amount of acrylate polymers, the graft layer of the graft polymer is prone to uneven thickness or incomplete coverage, the probability of exposure of the rubber phase acrylate particles increases, and the grafting points containing double bonds are also exposed, resulting in the decrease of the thermal stability of the graft copolymer. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and to provide an antioxidant dispersion liquid for a vinyl chloride graft copolymer, which can significantly improve the thermal stability of the rubber phase acrylate graft vinyl chloride copolymer, and an application method of the antioxidant dispersion liquid for the vinyl chloride graft copolymer.

[0007] The technical scheme adopted by the present application to solve its technical problems is: the vinyl chloride graft copolymer antioxidant dispersion liquid, characterized in that: the antioxidant composition is 1-40 parts by weight, the alkyl phenol polyoxyethylene ether emulsifier is 0.01-0.4 parts by weight, the desalted water is 60-99 parts by weight, and the water-soluble polymer is 0.2-0.3 parts by weight.

[0008] The antioxidant composition includes antioxidant 245 (Irganox 245) 5-15 parts by weight, antioxidant 1076 (Irganox 1076) 5-15 parts by weight, and antioxidant 1010 (Irganox 1010) 5-15 parts by weight. Triethylene glycol Bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] 25-35 parts, sulfur ester antioxidant 65-75 parts.

[0009] The inventors found that for the polymerization process of vinyl chloride grafting low glass transition temperature cross-linked structure-containing acrylic latex particles, antioxidant 234 does not have obvious inhibitory effect, but can provide the effect of improving the molecular defect structure of the polymer during polymerization, absorbing unsaturated double bonds, and improving the thermal stability of the polymer; meanwhile, the antioxidant is prepared into an antioxidant dispersion liquid by using the above-mentioned formula, compared with the traditional single use, on the one hand, it is more beneficial to uniform dispersion in the polymerization system, and fully improves the molecular defect structure of each part of the material; on the other hand, when antioxidant 245 and sulfur ester antioxidant are used in the above-mentioned proportion, antioxidant 245 is mainly used to capture free radicals generated by thermal cracking of olefinic bonds, and provides the early stage stability of the polymer, while the sulfur ester compound has strong reducing property, and is mainly used to eliminate peroxides generated in the thermal cracking of polyvinyl chloride and acrylate polymer, avoid further decomposition of resin performance, cause performance degradation, and further improve the thermal stability of the copolymer; and the density of the finally formed antioxidant dispersion liquid is close to that of water, and it is not easy to be chromatographed or precipitated, fully meeting the stability requirements of the antioxidant dispersion liquid itself.

[0010] Preferably, the sulfur ester antioxidant includes one or a mixture of any proportion of DLTDP (dilauryl thiodipropionate), DTDTP (3,3-dithiodipropionic acid ditridecyl ester), and DMTDP (3,3'-thiodipropionic acid dimyristyl ester).

[0011] The above-mentioned sulfur ester antioxidant has stronger synergistic effect with antioxidant 245.

[0012] Preferably, the alkyl phenol polyoxyethylene ether emulsifier is OP-9, OP-10, or OP-13, and the HLB (hydrophilic-lipophilic balance value) is between 10 and 14.

[0013] Preferably, the emulsifier is more beneficial to ensure the stability of the antioxidant dispersion liquid, and is not easy to be stratified and precipitated.

[0014] Preferably, the water-soluble polymer is polyvinyl alcohol with an average molecular weight of 1500-2500, an alcoholysis degree of 75-95%, and an average viscosity of 4% aqueous solution of 25-50 mP·s (20℃, Brookfield viscosity), or hydroxypropyl methylcellulose with a viscosity of 2% aqueous solution of 10-120 mPa·s (20℃, Brookfield viscosity).

[0015] The preferred water-soluble polymer is more conducive to uniform and stable dispersion of the antioxidant in the dispersion.

[0016] The use of the antioxidant dispersion of any one of the vinyl chloride graft copolymer according to the present application, characterized in that it comprises the following steps:

[0017] 1) The antioxidant composition, alkylphenol polyoxyethylene ether emulsifier and desalted water are mixed in proportion, and then subjected to shear emulsification at 80-95℃, and then the water-soluble polymer is added to obtain an antioxidant dispersion, and the obtained antioxidant dispersion is mixed with a terminating agent to obtain a composite terminating agent;

[0018] 2) In the vinyl chloride suspension graft polymerization system, antioxidant 245, acrylate latex, desalted water, vinyl chloride monomer, dispersant, initiator, pH regulator are added, and polymerization is carried out at 40-70℃, and the composite terminating agent obtained in step 1) is added at the end of the reaction to complete the reaction.

[0019] The antioxidant 245 is added in the polymerization process to ensure the dispersion effect of the antioxidant 245, and to capture the free radicals generated by the thermal cracking of the olefinic bond in the early stage of the polymerization reaction to improve the thermal stability of the final copolymer. Before termination, the antioxidant dispersion and the terminating agent are compounded to form a composite terminating agent, and the antioxidant 245 and the sulfur ester antioxidant participate in the termination reaction together with the terminating agent, so as to minimize the influence of the sulfur ester antioxidant on the polymerization process, fully utilize the sulfur ester antioxidant to eliminate peroxides generated in the thermal cracking of polyvinyl chloride and acrylate polymers, avoid further decomposition of the resin performance and cause performance degradation, and further improve the thermal stability of the copolymer.

[0020] The characteristics of antioxidant 245 and sulfur ester antioxidant are fully utilized to ensure the polymerization process and improve the thermal stability effect.

[0021] The acrylate latex is prepared by emulsion polymerization process, and the emulsifier that can be used includes basic saponified products of fatty acids, such as potassium stearate and potassium laurate, or sulfuric acid and sulfonate salts of fatty alcohols, such as sodium dodecyl sulfate and sodium dodecyl benzene sulfonate, without limitation.

[0022] Other auxiliary agents such as initiators used in polymerization can also be added as needed, such as thermal initiators, inorganic salts such as potassium persulfate, organic peroxides such as azobisisoheptane, or oxidation-reduction initiators.

[0023] Preferably, in the composite terminator of step 1), the content of antioxidant 245 is 100-500 ppm based on the dry basis of the antioxidant relative to the content of vinyl chloride monomer in step 2).

[0024] Preferably, the content of antioxidant 245 in step 2) is 10-500 ppm relative to the content of vinyl chloride monomer.

[0025] Preferably, in the composite terminator of step 1), the content of antioxidant 245 is 100-500 ppm based on the dry basis of the antioxidant relative to the content of vinyl chloride monomer in step 2).

[0026] Preferably, the acrylate monomer is ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate.

[0027] Preferably, the dispersant in step 2) is polyvinyl alcohol with an alcoholysis degree of 65-92% and a 4% aqueous solution viscosity of 5-50 mP·s (20°C, Brookfield viscosity), or methylcellulose or hydroxypropyl methylcellulose with a 2% aqueous solution viscosity of 10-120 mPa·s (20°C, Brookfield viscosity).

[0028] The preferred dispersant can ensure similar properties to the composite antioxidant dispersion, improve the dispersion effect of the antioxidant dispersion and the terminator, and reduce the influence of component complexity on the performance of the resin.

[0029] Compared with the prior art, the present application has the beneficial effects that the characteristics of antioxidant 245 having no effect on the polymerization process of low glass transition temperature cross-linked structure-containing acrylic latex particles grafted with vinyl chloride are found, the dispersion effect of antioxidant 245 in the polymer material is improved, the synergistic complementary effect of antioxidant 245 and sulfur ester antioxidant in the copolymer system is found, and the thermal stability function of the antioxidant is further improved, the antioxidant is made into an antioxidant dispersion, and is added before the termination of the polymerization process, so that higher thermal stability and dispersion effect are obtained, and the antioxidant dispersion itself has good standing stability and is suitable for storage and transportation. DETAILED DESCRIPTION

[0030] The present application will be further described below in conjunction with examples, and example 2 is the best embodiment of the present application.

[0031] In the following examples, polyvinyl alcohol dispersant FS-22H is a product of Sinopec Chuanwei Chemical Co., Ltd.

[0032] Hydroxypropyl methyl cellulose FON50 is a dispersant product of Shin Nittsu Corporation, Japan.

[0033] Polyvinyl alcohol KH-20 is a dispersant product of Mitsubishi Group, Japan.

[0034] Polyvinyl alcohol dispersant FS-20 is a product of Sinopec Chuanwei Chemical Co., Ltd.

[0035] Hydroxypropyl methyl cellulose E50 is a product of Dow Chemical Company, USA.

[0036] Example 1

[0037] An antioxidant dispersant solution for vinyl chloride graft copolymer was prepared by mixing antioxidant DLTDP 28 parts, antioxidant 245 12 parts, desalted water 60 parts, and emulsifier OP-10 1.6 parts at 85°C using a Fruenke FA25 shear emulsifier at 15000 rpm for 10 minutes, adding polyvinyl alcohol dispersant FS-22H 0.25 parts, and after stabilization, cooling to below 30°C, to obtain an antioxidant dispersant solution with an antioxidant content of 40%. The prepared emulsion was placed at room temperature in the dark for 5 days without separation.

[0038] Application of an antioxidant dispersant solution for vinyl chloride graft copolymer, comprising the following steps:

[0039] 1) DEHA terminator 0.17 parts (dosage about 80 ppm, relative to vinyl chloride monomer mass) and antioxidant dispersant solution 1.58 parts (antioxidant dosage about 300 ppm, relative to vinyl chloride monomer mass) were mixed to form a composite terminator.

[0040] 2) Into a stainless steel reaction kettle equipped with a stirrer, 245 antioxidant 0.21 parts (about 100 ppm, relative to vinyl chloride monomer mass), desalted water 4000 parts, polyvinyl alcohol KH-20 dispersant 0.1 parts, hydroxypropyl methyl cellulose FON50 dispersant 5.9 parts, di(2-ethylhexyl) peroxydicarbonate initiator 3.0 parts, and the following butyl acrylate latex 403 parts were added, after vacuum extraction to remove oxygen, vinyl chloride monomer 2100 parts was added, the stirring was started and the temperature was raised to 57.9°C for grafting reaction. When the pressure in the kettle dropped by 0.15 MPa from the highest point, the composite terminator obtained in step 1) was added, after removal of residual monomer and slurry centrifugal dewatering operation, the wet material was dried at 60°C for 8.0 hours to obtain vinyl chloride graft acrylate latex graft copolymer powder.

[0041] The butyl acrylate latex preparation method is as follows: 500.0 parts of butyl acrylate, 25 parts of diallyl phthalate, 7.5 parts of potassium laurate, 1.0 part of potassium persulfate, 0.10 part of potassium hydroxide and 1000.0 parts of desalted water are added into a four-mouth glass reaction flask provided with a reflux condenser, and then the mixture is reacted at 63°C for 4 hours under the protection of nitrogen and stirring, so that butyl acrylate latex with cross-linking structure having a conversion rate of 99.0% and a solid content of not less than 33.0% is obtained.

[0042] Example 2

[0043] An antioxidant dispersion liquid for vinyl chloride graft copolymer is prepared by mixing 21 parts of antioxidant DTDTP, 9 parts of antioxidant 245, 70 parts of desalted water and 0.24 parts of emulsifier OP-13 at 90°C under stirring for 10 minutes by using a Fluck FA25 shear emulsifier at 10000 rpm, then adding 0.25 parts of polyvinyl alcohol dispersant FS-20 to stabilize the dispersion liquid, and then cooling to below 30°C. The prepared emulsion has no stratification phenomenon under the condition of normal temperature and light avoidance for 7 days.

[0044] Application of the antioxidant dispersion liquid for vinyl chloride graft copolymer, on the basis of Example 1, the amount of 245 antioxidant added before polymerization is changed to 0.11 parts (about 50 ppm, relative to the mass of vinyl chloride monomer), the DEHA terminator in the composite terminator added at the end of reaction is changed to 0.63 parts (the amount is about 300 ppm, relative to the mass of vinyl chloride monomer), the amount of antioxidant dispersion liquid is changed to 1.05 parts (the amount of antioxidant is about 150 ppm, relative to the mass of vinyl chloride monomer), and other conditions are the same as those in Example 1.

[0045] Example 3

[0046] An antioxidant dispersion liquid for vinyl chloride graft copolymer is prepared by mixing 6.8 parts of antioxidant DMDTP, 3.2 parts of antioxidant 245, 90 parts of desalted water and 0.7 parts of emulsifier OP-9 at 90°C under stirring for 10 minutes by using a Fluck FA25 shear emulsifier at 20000 rpm, then adding 0.20 parts of hydroxypropyl methyl cellulose dispersant E50 to stabilize the dispersion liquid, and then cooling to below 25°C. The prepared dispersion liquid has no obvious stratification phenomenon under the condition of normal temperature and light avoidance for 7 days.

[0047] Application of an antioxidant dispersion liquid for a vinyl chloride graft copolymer, on the basis of Example 1, the amount of 245 antioxidant added before polymerization was changed to 0.32 parts (about 150 ppm, relative to the mass of vinyl chloride monomer), in the composite terminator added at the end of the reaction, the DEHA terminator was changed to IPHA terminator 0.42 parts (about 200 ppm, relative to the mass of vinyl chloride monomer), the antioxidant dispersion liquid was changed to 5.46 parts (antioxidant amount about 260 ppm, relative to the mass of vinyl chloride monomer), and the other conditions were the same as in Example 1.

[0048] Example 4

[0049] An antioxidant dispersion liquid for a vinyl chloride graft copolymer, antioxidant DTDTP 15 parts, antioxidant 245 5 parts, desalted water 80 parts, and emulsifier OP-10 0.15 parts were mixed at 95°C using a Flacktek FA25 shear emulsifier 20000 rpm for 10 minutes, then 0.25 parts of polyvinyl alcohol dispersant KH-20 was added to stabilize the dispersion liquid, and then the temperature was lowered to below 25°C, to obtain an antioxidant dispersion liquid with an antioxidant content of 20%. The prepared dispersion liquid was placed in the dark at room temperature for 5 days without obvious layering phenomenon.

[0050] Application of an antioxidant dispersion liquid for a vinyl chloride graft copolymer, on the basis of Example 1, the amount of 245 antioxidant added before polymerization was changed to 0.63 parts (about 300 ppm, relative to the mass of vinyl chloride monomer), in the composite terminator added at the end of the reaction, the DEHA terminator was changed to IPHA terminator 0.84 parts (about 400 ppm, relative to the mass of vinyl chloride monomer), the antioxidant dispersion liquid was changed to 4.62 parts (antioxidant amount about 440 ppm, relative to the mass of vinyl chloride monomer), and the other conditions were the same as in Example 1.

[0051] Example 5

[0052] An antioxidant dispersion liquid for a vinyl chloride graft copolymer and its application, on the basis of Example 1, the butyl acrylate latex was replaced with ethyl acrylate latex, and the other conditions were the same as in Example 1.

[0053] Comparative Example 1

[0054] An antioxidant dispersion liquid for a vinyl chloride graft copolymer and its application, on the basis of Example 1, no antioxidant 245 and antioxidant dispersion liquid was used before the vinyl chloride graft polymerization process, only 0.17 parts of DEHA (about 80 ppm, relative to the mass of vinyl chloride monomer) was added at the end of the polymerization, and the other conditions were the same as in Example 1.

[0055] Comparative Example 2

[0056] An antioxidant dispersing liquid for vinyl chloride graft copolymer and its application, on the basis of Example 1, without using the antioxidant dispersing liquid, only adding antioxidant 245 0.21 parts (about 100 ppm, relative to the mass of vinyl chloride monomer) before polymerization, and only adding terminating agent DEHA 0.17 parts (about 80 ppm, relative to the mass of vinyl chloride monomer) at the end, and the other conditions are the same as Example 1.

[0057] Comparative Example 3

[0058] An antioxidant dispersing liquid for vinyl chloride graft copolymer and its application, on the basis of Example 1, only adding terminating agent DEHA 0.17 parts (about 80 ppm, relative to the mass of vinyl chloride monomer) at the end of polymerization and the composite antioxidant dispersing liquid 1.58 parts (300 ppm, relative to the mass of vinyl chloride monomer) in Example 1, without adding antioxidant 245 before the start of polymerization, and the other conditions are the same as Example 1.

[0059] Performance test

[0060] The copolymers obtained in the above examples and comparative examples were sieved to remove coarse materials above 20 mesh, and samples were tested under GB / T 15595-1995 standard, and the results are shown in Table 1.

[0061] Table 1 Performance test results

[0062] .

[0063] The above is only a preferred embodiment of the present application, and is not intended to limit the other forms of the present application. 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 of the above examples made without departing from the technical solution of the present application, according to the technical essence of the present application, still falls within the protection scope of the technical solution of the present application.

Claims

1. The application of an antioxidant dispersion for vinyl chloride graft copolymers, characterized in that: The antioxidant dispersion for vinyl chloride graft copolymer comprises, by weight, 1-40 parts of antioxidant composition, 0.01-0.4 parts of alkylphenol polyoxyethylene ether emulsifier, 60-99 parts of deionized water, and 0.2-0.3 parts of water-soluble polymer; The antioxidant composition comprises, by weight, 245 parts of antioxidant (25-35 parts) and 65-75 parts of thioester antioxidant; the alkylphenol polyoxyethylene ether emulsifier is OP-9, OP-10 or OP-13, and the HLB content is between 10 and 14. Includes the following steps: 1) The antioxidant composition, alkylphenol polyoxyethylene ether emulsifier and desalinated water are sheared and emulsified at 80~95℃, and then water-soluble polymer is added and mixed to obtain an antioxidant dispersion. The obtained antioxidant dispersion is mixed with a terminator to obtain a composite terminator. 2) In the vinyl chloride suspension graft polymerization system, antioxidant 245, acrylate latex, deionized water, vinyl chloride monomer, dispersant, initiator, and pH adjuster are added, and polymerization is carried out at 40~70℃. When terminating, the composite terminator obtained in step 1) is added to complete the reaction.

2. The application of the antioxidant dispersion for vinyl chloride graft copolymers according to claim 1, characterized in that: The thioester antioxidants include one or a mixture of several antioxidants DLTDP, DTDTP, and DMTDP in any proportion.

3. The application of the antioxidant dispersion for vinyl chloride graft copolymers according to claim 1, characterized in that: The water-soluble polymer is polyvinyl alcohol with an average molecular weight of 1500-2500, a degree of alcoholysis of 75-95%, and an average viscosity of 25-50 mPa•s in a 4% aqueous solution, or hydroxypropyl methylcellulose with a viscosity of 10-120 mPa•s in a 2% aqueous solution.

4. The application of the antioxidant dispersion for vinyl chloride graft copolymers according to claim 1, characterized in that: In the composite terminator described in step 1), the content of antioxidant 245, on an antioxidant dry basis, is 100~500 ppm relative to the content of vinyl chloride monomer in step 2).

5. The application of the antioxidant dispersion for vinyl chloride graft copolymers according to claim 1, characterized in that: In step 2), the content of antioxidant 245 relative to vinyl chloride monomer is 10~500 ppm.

6. The application of the antioxidant dispersion for vinyl chloride graft copolymers according to claim 1, characterized in that: In the composite terminator described in step 1), the terminator content, calculated on an antioxidant dry basis, is 50-500 ppm relative to the vinyl chloride monomer content in step 2).

7. The application of the antioxidant dispersion for vinyl chloride graft copolymers according to claim 1, characterized in that: The dispersant mentioned in step 2) is polyvinyl alcohol with a degree of alcoholysis of 65-92% and a viscosity of 5-50 mPa•s in a 4% aqueous solution, or methylcellulose or hydroxypropyl methylcellulose with a viscosity of 10-120 mPa•s in a 2% aqueous solution.