A transparent impact modifier for polyvinyl chloride with yellowing resistance and its preparation method

Abstract

The present invention relates to the technical field of impact modifiers, and provides a yellowing-resistant transparent impact modifier for polyvinyl chloride and a preparation method thereof. The impact modifier is a graft copolymer composed of a hard core layer, a soft core layer and a hard shell layer; the hard core layer is a vinyl polymer, the soft core layer is an acrylate elastomer, and the hard shell layer is a methacrylate polymer, and the mass ratio is (50-60):(30-40):(10-20). The method includes: (1) adding styrene, α-methylstyrene, an emulsifier, a crosslinking agent, water and an initiator to obtain a hard core layer emulsion; (2) adding an alkyl acrylate, an emulsifier, a crosslinking agent, water and an initiator to obtain a hard core-soft core layer emulsion; (3) adding methyl methacrylate, an emulsifier, a crosslinking agent, a chain transfer agent, water and an initiator to obtain a hard core-soft core-hard shell layer emulsion; and then demulsifying to obtain the impact modifier. The impact modifier provided by the present invention takes into account both yellowing resistance and impact resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of impact modifiers for polyvinyl chloride, and particularly to a transparent impact modifier for polyvinyl chloride with yellowing resistance and a preparation method thereof. Background Art

[0002] Polyvinyl chloride material is the third largest synthetic polymer plastic in the world in terms of production volume, with a wide range of application fields and a very large demand. Due to the good chemical stability, corrosion resistance, high hardness, high strength, fire resistance and flame retardancy (self-extinguishing), reliable insulation performance, smooth and flat surface, non-absorbent, non-deformable, easy to process and other advantages of polyvinyl chloride material itself, and the polyvinyl chloride plastic itself has a certain transparency, the advantages of polyvinyl chloride transparent products are very obvious, and it is an excellent thermoforming material. Polyvinyl chloride material can replace some stainless steel and other corrosion-resistant synthetic materials, and is widely used in chemical industry, petroleum, electroplating, water purification treatment equipment, environmental protection equipment, mining, medicine, electronics, communication and decoration industries.

[0003] However, polyvinyl chloride products are a kind of hard and brittle materials with poor impact strength. Impact modifiers need to be added during the forming process. General transparent impact modifiers usually add styrene to balance the refractive index and improve transparency, but at the same time, it will bring problems of poor high-temperature resistance and yellowing resistance. Therefore, it is difficult to balance the transparency, impact resistance and yellowing resistance of current polyvinyl chloride products, which is very likely to affect the final performance and appearance of polyvinyl chloride transparent products. Summary of the Invention

[0004] In order to solve the problem that the transparent impact modifier added in the polyvinyl chloride transparent product cannot balance yellowing resistance, the present invention provides a transparent impact modifier for polyvinyl chloride and a preparation method thereof.

[0005] In order to achieve the object of the present invention, the following technical scheme is adopted:

[0006] The present invention provides a transparent impact modifier for polyvinyl chloride with yellowing resistance in the first aspect. The transparent impact modifier for polyvinyl chloride is a graft copolymer composed of a hard core layer, a soft core layer and a hard shell layer;

[0007] The hard core layer is mainly prepared from styrene, α-methylstyrene and water;

[0008] The soft core layer is mainly prepared from an alkyl acrylate and water. The alkyl acrylate is selected from butyl acrylate and amyl acrylate;

[0009] The hard shell layer is a methacrylate polymer;

[0010] Among them, the mass ratio between the hard core layer, the soft core layer and the hard shell layer is (50 - 60):(30 - 40):(10 - 20).

[0011] In some specific embodiments, the hard core layer is mainly prepared from the following components by weight:

[0012] Styrene 27 - 33,

[0013] α-Methylstyrene 23 - 27,

[0014] Water 75 - 90;

[0015] Based on the total weight of the styrene and the α-methylstyrene being 100%, the raw materials for preparing the hard core layer further include:

[0016] Emulsifier 0.5% - 0.7%,

[0017] Initiator 0.04% - 0.08%,

[0018] Crosslinking agent 0.8% - 1%.

[0019] In some embodiments, the soft core layer is mainly prepared from the following components by weight:

[0020] Alkyl acrylate 30 - 40,

[0021] Water 45 - 60;

[0022] Based on the weight of the alkyl acrylate being 100%, the raw materials for preparing the soft core layer further include:

[0023] Emulsifier 0.5% - 0.7%,

[0024] Initiator 0.04% - 0.08%,

[0025] Crosslinking agent 0.8% - 1.2%.

[0026] In some embodiments, the hard shell layer is prepared from the following components by weight:

[0027] Methyl methacrylate 10 - 20,

[0028] Water 15 - 30;

[0029] Based on the weight of the methyl methacrylate being 100%, the raw materials for preparing the hard shell layer further include:

[0030] Emulsifier 0.5% - 0.7%,

[0031] Initiator 0.04% - 0.08%,

[0032] Crosslinking agent: 0.3% - 0.5%,

[0033] Chain transfer agent: 0.1% - 0.2%.

[0034] In some specific embodiments, the chain transfer agent is dodecyl mercaptan.

[0035] In some embodiments, the emulsifier is selected from sodium alkyl sulfonate and / or sodium alkyl benzene sulfonate.

[0036] In some embodiments, the crosslinking agent is selected from one or more of allyl methacrylate, ethylene glycol dimethacrylate, 1,6 - hexanediol diacrylate, or ethylene glycol dimethacrylate.

[0037] In some embodiments, the initiator is selected from water - soluble redox composite initiators; wherein, the oxidant in the water - soluble redox composite initiator is one or more of ammonium persulfate, potassium persulfate, di - isopropylbenzene hydroperoxide, or benzoyl peroxide; the reductant is sodium formaldehyde sulfoxylate, or a mixture of sodium formaldehyde sulfoxylate with ethylenediaminetetraacetic acid and ferrous sulfate.

[0038] In a second aspect, the present invention provides a preparation method of a transparent impact modifier for polyvinyl chloride, comprising:

[0039] (1) Placing styrene, α - methylstyrene, emulsifier, crosslinking agent, and water in a reaction kettle, heating to the polymerization temperature, adding the initiator, and obtaining a hard - core layer emulsion after reaction and ripening;

[0040] (2) Continuing to add alkyl acrylate, emulsifier, crosslinking agent, and water into the reaction kettle, heating to the polymerization temperature, adding the initiator, and obtaining a hard - core / soft - core layer emulsion after reaction and ripening;

[0041] (3) Continuing to add methyl methacrylate, emulsifier, crosslinking agent, chain transfer agent, and water into the reaction kettle, heating to the polymerization temperature, adding the initiator, and obtaining a hard - core / soft - core / hard - shell layer emulsion after reaction and ripening;

[0042] Flocculating and demulsifying the obtained hard - core / soft - core / hard - shell layer emulsion with a flocculant, washing and drying to obtain a transparent impact modifier for polyvinyl chloride.

[0043] In some specific embodiments, in steps (1) and (2), the polymerization reaction is carried out at 60 - 65 °C for 3 - 4 h;

[0044] In step (3), the polymerization reaction temperature is 65 - 70 °C for 2 - 3 h;

[0045] The flocculant is calcium chloride.

[0046] The technical solution provided by the present invention has the following beneficial effects:

[0047] The transparent impact modifier for polyvinyl chloride provided by the present invention has a three-layer structure of hard core-soft core-hard shell. Using an alkyl acrylate as the soft core layer to encapsulate styrene monomers into the core enables the modifier to have good impact resistance while taking into account the yellowing resistance performance.

[0048] The modifier provided by the present invention also moderately crosslinks the hard shell layer, reducing the oligomers generated by incomplete depolymerization of methyl methacrylate polymers and reducing yellowing. At the same time, a chain transfer agent is added to the raw material components of the hard shell core layer, improving the fluidity of the modifier in polyvinyl chloride and also enhancing the impact resistance of the product. Detailed Description of the Invention

[0049] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention and are not intended to limit the present invention.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The term "and / or" as used herein may include any and all combinations of one or more of the related listed items.

[0051] The present invention provides a yellowing-resistant transparent impact modifier for polyvinyl chloride. The transparent impact modifier for polyvinyl chloride is a graft copolymer composed of a hard core layer, a soft core layer, and a hard shell layer;

[0052] The hard core layer is mainly prepared from styrene, α-methylstyrene, and water;

[0053] The soft core layer is mainly prepared from an alkyl acrylate and water. The alkyl acrylate is selected from butyl acrylate and amyl acrylate;

[0054] The hard shell layer is a methacrylate polymer;

[0055] Among them, the mass ratio of the hard core layer, the soft core layer, and the hard shell layer is (50-60):(30-40):(10-20), for example, 55:35:15, 52:30:15.

[0056] In some specific embodiments, the hard core layer of the impact modifier provided by the present invention is mainly prepared from the following components in parts by weight:

[0057] Styrene 27-33,

[0058] α-Methylstyrene 23-27,

[0059] Water 75-90;

[0060] Based on the total weight of styrene and α-methylstyrene being 100%, the raw materials for preparing the hard core layer further include:

[0061] Emulsifier 0.5% - 0.7%,

[0062] Initiator 0.04% - 0.08%,

[0063] Crosslinking agent 0.8% - 1%.

[0064] In the hard core layer of the transparent impact modifier for polyvinyl chloride provided by the present invention, α-methylstyrene is used to replace part of styrene, improving the high temperature resistance of the product.

[0065] In some specific embodiments, the soft core layer of the impact modifier provided by the present invention is mainly prepared from the following components in parts by weight:

[0066] Alkyl acrylate 30 - 40,

[0067] Water 45 - 60;

[0068] Based on the weight of the alkyl acrylate being 100%, the raw materials for preparing the soft core layer further include:

[0069] Emulsifier 0.5% - 0.7%,

[0070] Initiator 0.04% - 0.08%,

[0071] Crosslinking agent 0.8% - 1.2%.

[0072] In some specific embodiments, the hard shell layer of the impact modifier provided by the present invention is prepared from the following components in parts by weight:

[0073] Methyl methacrylate 10 - 20,

[0074] Water 15 - 30;

[0075] Based on the weight of the methyl methacrylate being 100%, the raw materials for preparing the hard shell layer further include:

[0076] Emulsifier 0.5% - 0.7%,

[0077] Initiator 0.04% - 0.08%,

[0078] Crosslinking agent 0.3% - 0.5%,

[0079] Chain transfer agent 0.1% - 0.2%.

[0080] The transparent impact modifier for polyvinyl chloride provided by the present invention is also moderately cross-linked in the hard shell layer, reducing the oligomers generated by incomplete depolymerization of methyl methacrylate and reducing the yellowing phenomenon of the product; meanwhile, the added chain transfer agent can improve the fluidity of the modifier in polyvinyl chloride and enhance the impact resistance of the product.

[0081] In some embodiments, the chain transfer agent is dodecyl mercaptan.

[0082] In some embodiments, the emulsifier selected by the present invention is selected from sodium alkyl sulfonate and / or sodium alkyl benzene sulfonate. The emulsifier has a relatively high decomposition temperature, high heat resistance and strong emulsifying ability, greatly reducing the amount of emulsifier used. At the same time, the flocculation-drying production process can also reduce the residue of the emulsifier and reduce the yellowing problem caused by small emulsifier molecules.

[0083] In some embodiments, the cross-linking agent in the impact modifier provided by the present invention is selected from one or more of allyl methacrylate, ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate or ethylene glycol dimethacrylate.

[0084] In some embodiments, the initiator in the present invention is selected from water-soluble redox composite initiators; among them, the oxidant in the water-soluble redox composite initiator is selected from one or more of ammonium persulfate, potassium persulfate, diisopropylbenzene hydroperoxide or benzoyl peroxide; the reducing agent is selected from sodium formaldehyde sulfoxylate, or a mixture of sodium formaldehyde sulfoxylate with ethylenediaminetetraacetic acid and ferrous sulfate.

[0085] The present invention also provides a method for preparing the above-mentioned transparent impact modifier for polyvinyl chloride, including:

[0086] (1) Placing styrene, α-methylstyrene, emulsifier, cross-linking agent and water in a reaction kettle, heating to the polymerization temperature and then adding the initiator, and obtaining a hard core layer emulsion after reaction and ripening;

[0087] (2) Continuing to add alkyl acrylate, emulsifier, cross-linking agent and water into the reaction kettle, heating to the polymerization temperature and then adding the initiator, and obtaining a hard core-soft core layer emulsion after reaction and ripening;

[0088] (3) Continuing to add methyl methacrylate, emulsifier, cross-linking agent, chain transfer agent and water into the reaction kettle, heating to the polymerization temperature and then adding the initiator, and obtaining a hard core-soft core-hard shell layer emulsion after reaction and ripening;

[0089] Flocculating and demulsifying the obtained hard core-soft core-hard shell layer emulsion with a flocculant, and washing and drying to obtain a transparent impact modifier for polyvinyl chloride.

[0090] In some embodiments, in steps (1) and (2), the polymerization reaction is carried out at 60 - 65 °C for 3 - 4 h;

[0091] In step (3), the polymerization reaction temperature is 65 - 70 °C and it is carried out for 2 - 3 h;

[0092] In some preferred embodiments, the flocculant is selected from calcium chloride.

[0093] The following further illustrates the solution of the present invention through specific examples, but it should not be construed that the present invention is only limited thereto.

[0094] For the parts not specifying the specific experimental steps or conditions in the examples, the operations or conditions of the corresponding conventional experimental steps in the technical field can be followed. For the reagents not indicating the manufacturers, they are all conventional reagents existing in the art.

[0095] The raw material sources of the following examples are as follows:

[0096] Styrene: Lihuayi Lijin Refining & Chemical Co., Ltd., industrial pure;

[0097] α-Methylstyrene: Wuhan Jiyesheng Chemical Co., Ltd., industrial pure;

[0098] Butyl acrylate: Wanhua Chemical Group Co., Ltd., industrial pure;

[0099] Amyl acrylate: Hubei Xinhongli Chemical Co., Ltd., industrial pure;

[0100] Potassium persulfate: Yatai Electrochemical Co., Ltd., industrial pure;

[0101] Sodium alkyl sulfonate: Henan Lichi Fine Chemical Co., Ltd., industrial pure;

[0102] Sodium alkyl benzene sulfonate: Guangzhou Fufei Chemical Technology Co., Ltd., industrial pure.

[0103] Example 1

[0104] (1) Add 81 kg of styrene, 81 kg of α-methylstyrene, 0.81 kg of sodium alkyl sulfonate, 1.62 kg of allyl methacrylate, and 243 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 65 °C, add 0.0648 kg of potassium persulfate and 0.0648 kg of sodium formaldehyde sulfoxylate. After reacting for 3 h and aging, a hard core layer emulsion is obtained;

[0105] (2) Continuously add 108 kg of butyl acrylate, 0.54 kg of alkyl sulfonate, 162 kg of water, and 1.08 kg of allyl methacrylate into the reaction kettle. After heating to the polymerization temperature of 65 °C, add 0.0432 kg of potassium persulfate and 0.0432 kg of sodium formaldehyde sulfoxylate, and react for 3 h and then cure to obtain a core-shell emulsion;

[0106] (3) Continuously add 30 kg of methyl methacrylate, 0.15 kg of alkyl sulfonate, 45 kg of water, 0.15 kg of ethylene glycol dimethacrylate, and 0.03 kg of dodecyl mercaptan into the reaction kettle. After heating to the polymerization temperature of 70 °C, add 0.012 kg of potassium persulfate and 0.012 kg of sodium formaldehyde sulfoxylate, and react for 2 h and then cure to obtain a core-shell-core emulsion.

[0107] The above-prepared core-shell-core emulsion is subjected to calcium chloride flocculation and demulsification, then centrifuged and dried by a filter press, and then enters a drying bed for drying at 60 °C to finally obtain a powdery product.

[0108] Example 2

[0109] (1) Add 81 kg of styrene, 69 kg of α-methylstyrene, 0.75 kg of alkyl sulfonate, 1.5 kg of 1,6-hexanediol diacrylate, and 225 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 65 °C, add 0.06 kg of potassium persulfate and 0.06 kg of sodium formaldehyde sulfoxylate, and react for 4 h and then cure to obtain a core layer emulsion;

[0110] (2) Continuously add 90 kg of amyl acrylate, 0.45 kg of alkyl sulfonate, 135 kg of water, and 0.9 kg of 1,6-hexanediol diacrylate into the reaction kettle. After heating to the polymerization temperature of 65 °C, add 0.036 kg of potassium persulfate and 0.036 kg of sodium formaldehyde sulfoxylate, and react for 4 h and then cure to obtain a core-shell emulsion;

[0111] (3) Continuously add 60 kg of methyl methacrylate, 0.3 kg of alkyl sulfonate, 90 kg of water, 0.3 kg of ethylene glycol dimethacrylate, and 0.06 kg of dodecyl mercaptan into the reaction kettle. After heating to the polymerization temperature of 70 °C, add 0.024 kg of potassium persulfate and 0.024 kg of sodium formaldehyde sulfoxylate, and react for 3 h and then cure to obtain a core-shell-core emulsion.

[0112] The above-prepared core-shell-core emulsion is subjected to calcium chloride flocculation and demulsification, then centrifuged and dried by a filter press, and then enters a drying bed for drying at 60 °C to finally obtain a powdery product.

[0113] Example 3

[0114] (1) Add 93 kg of styrene, 69 kg of α-methylstyrene, 0.81 kg of alkylbenzene sulfonate, 1.62 kg of allyl methacrylate, and 243 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 60°C, add 0.0648 kg of potassium persulfate and 0.0648 kg of sodium formaldehyde sulfoxylate, and react for 3 h and then cure to obtain the core layer emulsion;

[0115] (2) Continuously add 108 kg of butyl acrylate, 0.54 kg of alkylbenzene sulfonate, 162 kg of water, and 1.08 kg of allyl methacrylate into the reaction kettle. After heating to the polymerization temperature of 60°C, add 0.0432 kg of potassium persulfate and 0.0432 kg of sodium formaldehyde sulfoxylate, and react for 3 h and then cure to obtain the core-shell layer emulsion;

[0116] (3) Continuously add 30 kg of methyl methacrylate, 0.15 kg of alkylbenzene sulfonate, 45 kg of water, 0.15 kg of ethylene glycol dimethacrylate, and 0.03 kg of dodecyl mercaptan into the reaction kettle. After heating to the polymerization temperature of 65°C, add 0.012 kg of potassium persulfate and 0.012 kg of sodium formaldehyde sulfoxylate, and react for 2 h and then cure to obtain the core-shell-core layer emulsion.

[0117] After the above-prepared core-shell-core layer emulsion is flocculated and demulsified by calcium chloride, it is dried by a filter press and then enters the drying bed, and is dried at 60°C to finally obtain a powdery product.

[0118] Example 4

[0119] (1) Add 87 kg of styrene, 75 kg of α-methylstyrene, 1.134 kg of alkyl sulfonate, 1.62 kg of allyl methacrylate, and 243 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 60°C, add 0.0324 kg of ammonium persulfate and 0.0324 kg of sodium formaldehyde sulfoxylate, and react for 3 h and then cure to obtain the core layer emulsion;

[0120] (2) Continuously add 108 kg of butyl acrylate, 0.756 kg of alkyl sulfonate, 162 kg of water, and 1.08 kg of allyl methacrylate into the reaction kettle. After heating to the polymerization temperature of 60°C, add 0.0216 kg of ammonium persulfate and 0.0216 kg of sodium formaldehyde sulfoxylate, and react for 3 h and then cure to obtain the core-shell layer emulsion;

[0121] (3) Continuously add 30 kg of methyl methacrylate, 0.21 kg of alkyl sulfonate, 45 kg of water, 0.15 kg of ethylene glycol dimethacrylate, and 0.03 kg of dodecyl mercaptan into the reaction kettle. After heating up to the polymerization temperature of 65°C, add 0.006 kg of ammonium persulfate and 0.006 kg of sodium formaldehyde sulfoxylate. After reacting for 2 h and aging, a core-shell-shell emulsion is obtained.

[0122] The core-shell-shell emulsion prepared above is subjected to calcium chloride flocculation and demulsification, then centrifuged and dried by a filter press, and then enters a drying bed for drying at 60°C to finally obtain a powdery product.

[0123] Example 5

[0124] (1) Add 99 kg of styrene, 81 kg of α-methylstyrene, 0.9 kg of alkyl sulfonate, 1.8 kg of ethylene glycol dimethacrylate, and 270 kg of water into a 1-ton reaction kettle. After heating up to the polymerization temperature of 60°C, add 0.072 kg of potassium persulfate and 0.072 kg of sodium formaldehyde sulfoxylate. After reacting for 3 h and aging, a core layer emulsion is obtained.

[0125] (2) Continuously add 90 kg of butyl acrylate, 0.45 kg of alkyl sulfonate, 135 kg of water, and 0.9 kg of ethylene glycol dimethacrylate into the reaction kettle. After heating up to the polymerization temperature of 60°C, add 0.036 kg of potassium persulfate and 0.036 kg of sodium formaldehyde sulfoxylate. After reacting for 3 h and aging, a core-shell layer emulsion is obtained.

[0126] (3) Continuously add 30 kg of methyl methacrylate, 0.15 kg of alkyl sulfonate, 45 kg of water, 0.15 kg of ethylene glycol dimethacrylate, and 0.03 kg of dodecyl mercaptan into the reaction kettle. After heating up to the polymerization temperature of 65°C, add 0.012 kg of potassium persulfate and 0.012 kg of sodium formaldehyde sulfoxylate. After reacting for 2 h and aging, a core-shell-shell emulsion is obtained.

[0127] The core-shell-shell emulsion prepared above is subjected to calcium chloride flocculation and demulsification, then centrifuged and dried by a filter press, and then enters a drying bed for drying at 60°C to finally obtain a powdery product.

[0128] Example 6

[0129] (1) Add 81 kg of styrene, 69 kg of α-methylstyrene, 0.75 kg of alkyl sulfonate, 1.5 kg of ethylene glycol dimethacrylate, and 225 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 63°C, add a mixture of 0.06 kg of potassium persulfate and 0.06 kg of sodium formaldehyde sulfoxylate (the mass ratio of sodium formaldehyde sulfoxylate to ethylenediaminetetraacetic acid and ferrous sulfate is 2:0.01:0.01). After reacting for 3.5 h and aging, a hard core layer emulsion is obtained;

[0130] (2) Continuously add 120 kg of amyl acrylate, 0.6 kg of alkyl sulfonate, 180 kg of water, and 1.2 kg of ethylene glycol dimethacrylate into the reaction kettle. After heating to the polymerization temperature of 63°C, add a mixture of 0.048 kg of potassium persulfate and 0.048 kg of sodium formaldehyde sulfoxylate (the mass ratio of sodium formaldehyde sulfoxylate to ethylenediaminetetraacetic acid and ferrous sulfate is 2:0.01:0.01). After reacting for 3.5 h and aging, a hard core-soft core layer emulsion is obtained;

[0131] (3) Continuously add 30 kg of methyl methacrylate, 0.15 kg of alkyl sulfonate, 45 kg of water, 0.15 kg of ethylene glycol dimethacrylate, and 0.03 kg of dodecyl mercaptan into the reaction kettle. After heating to the polymerization temperature of 68°C, add a mixture of 0.012 kg of potassium persulfate and 0.012 kg of sodium formaldehyde sulfoxylate (the mass ratio of sodium formaldehyde sulfoxylate to ethylenediaminetetraacetic acid and ferrous sulfate is 2:0.01:0.01). After reacting for 2.5 h and aging, a hard core-soft core-hard shell layer emulsion is obtained.

[0132] After the above-prepared hard core-soft core-hard shell layer emulsion is flocculated and demulsified with calcium chloride, it is centrifuged and dried by a filter press, and then dried in a drying bed at 60°C to finally obtain a powdery product.

[0133] Example 7

[0134] (1) Add 81 kg of styrene, 81 kg of α-methylstyrene, 0.81 kg of alkyl sulfonate, 1.296 kg of ethylene glycol dimethacrylate, and 243 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 65°C, add 0.0648 kg of diisopropylbenzene hydroperoxide and 0.0648 kg of sodium formaldehyde sulfoxylate. After reacting for 4 h and aging, a hard core layer emulsion is obtained;

[0135] (2) Continuously add 108 kg of butyl acrylate, 0.54 kg of alkyl sulfonate, 162 kg of water, and 0.864 kg of ethylene glycol dimethacrylate into the reaction kettle. After heating to the polymerization temperature of 65°C, add 0.0432 kg of diisopropylbenzene hydroperoxide and 0.0432 kg of sodium formaldehyde sulfoxylate. After reacting for 4 h and aging, a core-shell emulsion is obtained;

[0136] (3) Continuously add 30 kg of methyl methacrylate, 0.15 kg of alkyl sulfonate, 45 kg of water, 0.09 kg of ethylene glycol dimethacrylate, and 0.06 kg of dodecyl mercaptan into the reaction kettle. After heating to the polymerization temperature of 70°C, add 0.012 kg of diisopropylbenzene hydroperoxide and 0.012 kg of sodium formaldehyde sulfoxylate. After reacting for 3 h and aging, a core-shell-core shell emulsion is obtained.

[0137] The above-prepared core-shell-core shell emulsion is subjected to calcium chloride flocculation and demulsification, then centrifuged and dried by a filter press, and then enters a drying bed for drying at 60°C to finally obtain a powdery product.

[0138] Comparative Example 1

[0139] (1) Add 87 kg of styrene, 75 kg of α-methylstyrene, 108 kg of butyl acrylate, 1.35 kg of alkyl sulfonate, 2.70 kg of allyl methacrylate, and 405 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 60°C, add 0.108 kg of potassium persulfate and 0.108 kg of sodium formaldehyde sulfoxylate. After reacting for 4 h and aging, a core layer emulsion is obtained;

[0140] (2) Continuously add 30 kg of methyl methacrylate, 0.15 kg of alkyl sulfonate, 45 kg of water, 0.15 kg of ethylene glycol dimethacrylate, and 0.03 kg of dodecyl mercaptan into the reaction kettle. After heating to the polymerization temperature of 70°C, add 0.012 kg of potassium persulfate and 0.012 kg of sodium formaldehyde sulfoxylate. After reacting for 3 h and aging, a core-shell emulsion is obtained.

[0141] The above-prepared emulsion enters a drying tower for drying at 220°C to finally obtain a powdery product.

[0142] Comparative Example 2

[0143] (1) Add 87 kg of styrene, 75 kg of α-methylstyrene, 0.81 kg of alkyl sulfonate, 1.62 kg of allyl methacrylate, and 243 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 65 °C, add 0.0648 kg of potassium persulfate and 0.0648 kg of sodium formaldehyde sulfoxylate, and react for 4 h and then age to obtain the hard core layer emulsion;

[0144] (2) Continuously add 108 kg of methyl acrylate, 0.54 kg of alkyl sulfonate, 162 kg of water, and 1.08 kg of allyl methacrylate into the reaction kettle. After heating to the polymerization temperature of 65 °C, add 0.0432 kg of potassium persulfate and 0.0432 kg of sodium formaldehyde sulfoxylate, and react for 4 h and then age to obtain the hard core-soft core layer emulsion;

[0145] (3) Continuously add 30 kg of methyl methacrylate, 0.15 kg of alkyl sulfonate, 45 kg of water, 0.15 kg of ethylene glycol dimethacrylate, and 0.03 kg of dodecyl mercaptan into the reaction kettle. After heating to the polymerization temperature of 70 °C, add 0.012 kg of potassium persulfate and 0.012 kg of sodium formaldehyde sulfoxylate, and react for 3 h and then age to obtain the hard core-soft core-hard shell layer emulsion.

[0146] The obtained hard core-soft core-hard shell layer emulsion is subjected to flocculation and demulsification with calcium chloride, then dried by a filter press and sent to a drying bed for drying at 60 °C, and finally a powdery product is obtained.

[0147] Comparative Example 3

[0148] (1) Add 162 kg of styrene, 0.81 kg of alkyl sulfonate, 1.62 kg of allyl methacrylate, and 243 kg of water into a 1-ton reaction kettle. After heating to the polymerization temperature of 65 °C, add 0.0648 kg of potassium persulfate and 0.0648 kg of sodium formaldehyde sulfoxylate, and react for 4 h and then age to obtain the hard core layer emulsion;

[0149] (2) Continuously add 108 kg of butyl acrylate, 0.54 kg of alkyl sulfonate, 162 kg of water, and 1.08 kg of allyl methacrylate into the reaction kettle. After heating to the polymerization temperature of 65 °C, add 0.0432 kg of potassium persulfate and 0.0432 kg of sodium formaldehyde sulfoxylate, and react for 4 h and then age to obtain the hard core-soft core layer emulsion;

[0150] (3) Continue to add 30 kg of methyl methacrylate, 0.15 kg of alkyl sulfonate, 45 kg of water, 0.15 kg of ethylene glycol dimethacrylate, and 0.03 kg of dodecyl mercaptan into the reaction kettle. After heating to the polymerization temperature of 70 °C, add 0.012 kg of potassium persulfate and 0.012 kg of sodium formaldehyde sulfoxylate. After reacting for 3 h and curing, a core-shell-shell emulsion is obtained.

[0151] The core-shell-shell emulsion prepared above is subjected to flocculation and demulsification with calcium chloride, then dehydrated by a filter press and dried in a drying bed at 60 °C to finally obtain a powdery product.

[0152] Add the modifier obtained in the above example to the preparation process of polyvinyl chloride according to the following ratio. Specifically: at 85 °C, mix the raw materials in Table 1 in a high-speed mixer, and then discharge after cooling to 44 °C; then, pass the mixed reaction raw materials through a 40-mesh sieve and start mixing on a two-roll mill. The mixing parameters are shown in Table 2 below:

[0153] Table 1

[0154]

[0155] Table 2

[0156]

[0157] Take slices of polyvinyl chloride in the two-roll mill at different times according to T / CCASC 3002-2023 "Plasticized Polyvinyl Chloride by Two-Roll Mill for Dynamic Thermal Stability Test", and test the yellow index of the polyvinyl chloride slice samples according to GB / T 39822-2021 "Plastics - Determination of Yellow Index and Its Variation". The test results are shown in Table 3 below:

[0158] Table 3

[0159]

[0160] Mix the modifier obtained in the above example according to the ratio in Table 1 above, then pass through a 40-mesh sieve and mix on a two-roll mill (parameters refer to Table 2 above) and vulcanize into a plate on a flat vulcanizer (parameters refer to Table 4 below).

[0161] Table 4

[0162]

[0163] Prepare samples and test the notched Izod impact strength (Type A notch) according to GB-T 1043.1-2008 "Plastics - Determination of Charpy Impact Strength - Part 1: Non-Instrumented Impact Test". The test results are shown in Table 5 below:

[0164] Table 5

[0165]

[0166] From the above test results, the polyvinyl chloride material prepared by using the impact modifier with a hard core - soft core - hard shell three - layer structure provided by the present invention has a lower yellowing resistance index and a higher simply - supported beam impact strength.

Claims

1. A transparent impact modifier for polyvinyl chloride with yellowing resistance, characterized in that, The transparent impact modifier for polyvinyl chloride is a graft copolymer composed of a hard core layer, a soft core layer and a hard shell layer from the inside to the outside in sequence; The hard core layer is mainly prepared from styrene, α-methylstyrene and water; The soft core layer is mainly prepared from an alkyl acrylate and water, and the alkyl acrylate is selected from butyl acrylate and amyl acrylate; The hard shell layer is mainly prepared from methyl methacrylate and water; Among them, the mass ratio of the hard core layer, the soft core layer and the hard shell layer is (50~60):(30~40):(10~20), and a crosslinking agent is also added during the preparation processes of the hard core layer, the soft core layer and the hard shell layer.

2. The transparent impact modifier for polyvinyl chloride according to claim 1, wherein The hard core layer is mainly prepared from the following components in parts by weight: styrene 27~33, α-methylstyrene 23~27, water 75~90; Based on the total weight sum of the styrene and the α-methylstyrene being 100%, the raw materials for preparing the hard core layer further include: an emulsifier 0.5%~0.7%, an initiator 0.04%~0.08%, a crosslinking agent 0.8%~1%.

3. The transparent impact modifier for polyvinyl chloride according to claim 2, wherein The soft core layer is mainly prepared from the following components in parts by weight: an alkyl acrylate 30~40, water 45~60; Based on the weight of the alkyl acrylate being 100%, the raw materials for preparing the soft core layer further include: an emulsifier 0.5%~0.7%, an initiator 0.04%~0.08%, a crosslinking agent 0.8%~1.2%.

4. The transparent impact modifier for polyvinyl chloride according to claim 3, wherein The hard shell layer is mainly prepared from the following components in parts by weight: methyl methacrylate 10~20, water 15~30; Based on the weight of the methyl methacrylate being 100%, the raw materials for preparing the hard shell layer further include: an emulsifier 0.5%~0.7%, an initiator 0.04%~0.08%, a crosslinking agent 0.3%~0.5%, a chain transfer agent 0.1%~0.2%.

5. The transparent impact modifier for polyvinyl chloride according to claim 4, wherein, The chain transfer agent is selected from dodecyl mercaptan.

6. The transparent impact modifier for polyvinyl chloride according to any one of claims 2 to 5, characterized in that, The emulsifier is selected from sodium alkyl sulfonate and / or sodium alkyl benzene sulfonate.

7. The transparent impact modifier for polyvinyl chloride according to claim 6, characterized in that, The crosslinking agent is selected from one or more of allyl methacrylate, 1,6-hexanediol diacrylate or ethylene glycol dimethacrylate.

8. The transparent impact modifier for polyvinyl chloride according to claim 7, characterized in that, The initiator is selected from a water-soluble redox composite initiator; Among them, the oxidant in the water-soluble redox composite initiator is one or more of ammonium persulfate, potassium persulfate, diisopropylbenzene hydroperoxide or benzoyl peroxide; the reductant is sodium formaldehyde sulfoxylate, or a mixture of sodium formaldehyde sulfoxylate and ethylenediaminetetraacetic acid and ferrous sulfate.

9. The preparation method of the transparent impact modifier for PVC according to any one of claims 1 to 8, characterized in that, Including: (1) Put styrene, α-methylstyrene, an emulsifier, a crosslinking agent and water into a reaction kettle, heat up to the polymerization temperature and then add an initiator, and obtain a hard core layer emulsion after reaction and ripening; (2) Continuously add an alkyl acrylate, an emulsifier, a crosslinking agent and water into the reaction kettle, heat up to the polymerization temperature and then add an initiator, and obtain a hard core-soft core layer emulsion after reaction and ripening; (3) Continuously add methyl methacrylate, an emulsifier, a crosslinking agent, a chain transfer agent and water into the reaction kettle, heat up to the polymerization temperature and then add an initiator, and obtain a hard core-soft core-hard shell layer emulsion after reaction and ripening; The obtained core-shell-core emulsion is flocculated and demulsified with a flocculant, and a transparent impact modifier for polyvinyl chloride is obtained after washing and drying.

10. The preparation method according to claim 9, wherein In steps (1) and (2), the polymerization reaction is carried out at 60-65 °C for 3-4 h; In step (3), the polymerization reaction is carried out at 65-70 °C for 2-3 h; The flocculant is calcium chloride.

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