Preparation method of a highly weather-resistant PVC impact modifier

Abstract

The present invention belongs to the technical field of polymer material synthesis, and specifically provides a preparation method of a high weather-resistant PVC impact modifier, including the preparation of an AIM impact modifier: First, a double-layer core emulsion is synthesized step by step. The first and second core layer emulsions are prepared respectively with different monomers, emulsifiers and initiators, and after mixing, an inner core mixed solution is formed. A shell layer emulsion is prepared in a reaction kettle, and then coated with the inner core mixed solution to form an impact modifier solution. The shell layer fragments and oligomers are separated by high-speed centrifugation, washed with water and dried to obtain a powder, and the shell layer fragments and oligomers are separated; the preparation of an ACR impact modifier: Hexafluoropropylene gas participates in the reaction in a closed reactor to obtain an ACR seed emulsion; continue to introduce hexafluoropropylene, and batchwise add the core layer raw materials to form a core layer structure; mix the ACR core layer product with the shell layer monomers, emulsifiers and the separated oligomers, and after demulsification, wash with water and dry to obtain an ACR impact modifier that can improve the weather resistance of PVC.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material synthesis, and particularly relates to a preparation method of a high weather-resistant PVC impact modifier. Background Art

[0002] PVC impact modifiers are a class of chemical auxiliaries used to improve the impact resistance of polyvinyl chloride (PVC) materials. By adjusting their molecular structure or physical properties, the toughness, weather resistance, and processing performance of PVC products can be significantly improved.

[0003] Common PVC impact modifiers include CPE impact modifiers, ACM impact modifiers, and AIM impact modifiers. Chlorinated polyethylene (CPE) is a saturated polymer material, an impact modifier formed by chlorinating HDPE, which can significantly improve the toughness and impact performance of PVC products. At the same time, it can effectively promote the plasticization of PCV materials and improve their processing performance.

[0004] ACM impact modifiers are core-shell structure toughening modifiers formed by ultra-high elongation chlorinated polyethylene and acrylate polymers. The products have ultra-high elongation at break and excellent processing performance, significantly improving the toughness of PVC products and endowing PVC products with good processing performance at the same time.

[0005] AIM impact modifiers endow PVC products with higher impact strength and excellent weather resistance. At the same time, they can promote the plasticization of PVC materials and improve the processability. They are applicable to fields such as PVC profiles and PVC pipes. They can greatly improve the impact strength, have excellent weather resistance, and can promote the plasticization of PVC materials and improve the processability at the same time.

[0006] During the production process of each PVC impact modifier, it is inevitable to produce a small amount of by-products. During the core layer cross-linking process of AIM impact modifier synthesis, if the monomer concentration is too high, or the initiator distribution is uneven, resulting in insufficient reaction in some areas, local self-polymerization is likely to occur to generate oligomers. At the same time, during the compatibility process between the core layer and the shell layer, the difference in their compatibility will lead to an increase in interfacial tension and the formation of fragments. Or during the processing process, due to uneven stirring or temperature gradient, the shell layer structure breaks, and fragments will also be formed.

[0007] Due to their low molecular weight and insufficient cross-linking degree, oligomers cannot effectively absorb impact energy, resulting in weak points in the AIM dispersed phase. The shell layer fragments damage the integrity of the core-shell structure, weaken the stress dispersion ability, and make the material more prone to crack propagation when stressed. Summary of the Invention

[0008] In view of the above defects, the present invention provides a preparation method of a high weather-resistant PVC impact modifier, which can remove the oligomers and shell fragments of by-products in the AIM impact modifier and is used to improve the weather resistance of the ACR impact modifier.

[0009] To achieve the above object, the present invention provides the following technical solutions: A preparation method of a high weather-resistant PVC impact modifier, including the preparation of the AIM impact modifier and the preparation of the ACR impact modifier. The preparation of the AIM impact modifier is as follows:

[0010] Step 100: Prepare the AIM first core layer emulsion;

[0011] Step 101: Prepare the AIM second core layer emulsion;

[0012] Step 102: Mix the AIM first core layer emulsion and the AIM second core layer emulsion to form an AIM inner core mixture;

[0013] Step 103: Prepare the AIM shell emulsion;

[0014] Step 104: Mix the AIM inner core mixture and the AIM shell emulsion to prepare the AIM impact modifier liquid;

[0015] Step 105: Separate the shell fragments mainly composed of polypropyl methacrylate and acrylate oligomers in the AIM impact modifier liquid by a high-speed centrifuge, and wash and dry them with deionized water to obtain the final AIM impact modifier powder;

[0016] Step 106: Separate the acrylate oligomers from the shell fragments mainly composed of polypropyl methacrylate through a 5-20 nm ultrafiltration membrane. The separation end point is determined by the permeate flow rate dropping to 15% of the initial value;

[0017] The preparation of the ACR impact modifier is specifically as follows:

[0018] Step 200: Add deionized water, ACR core layer monomers, ACR emulsifiers, ACR cross-linking agents, and ACR initiators into a closed reactor and mix them. At the same time, introduce hexafluoropropylene gas. After the reaction, an ACR seed emulsion is obtained;

[0019] Step 201: Add the ACR seed emulsion and deionized water into a closed reactor, introduce hexafluoropropylene gas at the same time, and intermittently add ACR core layer monomers, ACR emulsifiers, ACR cross-linking agents, and ACR initiators. After mixing and reacting, keep it warm to obtain the core layer of the ACR particles;

[0020] Step 202: Add ACR shell monomer, ACR emulsifier and acrylate oligomer screened out in step 106 of preparing AIM impact modifier to the product obtained in step 201, in the weight percentage, the obtained product is 60-80 parts, ACR shell monomer is 18-36 parts and acrylate oligomer is 2-4 parts. After fully mixing, take out to break the emulsion, wash with water and dry to obtain ACR impact modifier.

[0021] As a further improvement of the present invention, step 100 specifically comprises adding deionized water, AIM first core layer monomer, first core layer emulsifier, first core layer initiator and first core layer crosslinker into a reactor to react and form an AIM first core layer emulsion; in terms of mass percentage, the deionized water is 60-65 parts, the AIM first core layer monomer is 30-35 parts, the first core layer emulsifier is 1.5-2 parts, the first core layer initiator is 1-1.5 parts and the first core layer crosslinker is 1-1.5 parts.

[0022] As a further improvement of the present invention, the AIM first core layer monomer is a mixture of n-butyl acrylate and methyl methacrylate, the first core layer emulsifier is one of sodium dodecyl sulfate or polyoxyethylene ether non-ionic emulsifier; the first core layer initiator is one of ammonium persulfate or APS water-soluble initiator; and the first core layer crosslinker is acrylamide.

[0023] As a further improvement of the present invention, the step 101 specifically comprises adding deionized water, N-methylpyrrolidone, AIM second core layer monomer, second core layer emulsifier, second core layer initiator and second core layer crosslinker to the high shear emulsifier to react to form an AIM second core layer emulsion; in terms of mass percentage, the deionized water is 60-65 parts, the N-methylpyrrolidone is 6-8 parts, the AIM second core layer monomer is 25-30 parts, the second core layer emulsifier is 1.5-2 parts, the second core layer initiator is 1-1.5 parts and the second core layer crosslinker is 1-1.5 parts.

[0024] As a further improvement of the present invention, the AIM second core layer monomer is a mixture of ethyl methacrylate and styrene; the second core layer emulsifier is sodium dodecylbenzene sulfonate or a composite emulsification system; the second core layer initiator is an oil-soluble initiator or an oxidation-reduction initiation system, and the second core layer crosslinker is acrylamide.

[0025] As a further improvement of the present invention, the step 103 is specifically to add deionized water, AIM shell monomer, AIM shell emulsifier and AIM shell auxiliary agent into the reactor to react to form an AIM shell emulsion, which comprises 65-70 parts of deionized water, 25-30 parts of AIM shell monomer, 2-2.25 parts of AIM shell emulsifier and 0.5-0.75 parts of AIM shell auxiliary agent in mass percentage.

[0026] As a further improvement of the present invention, the AIM shell monomer is propyl methacrylate; the AIM shell emulsifier is one of sodium dodecyl sulfate or polysorbate; the AIM shell auxiliary agent is a mixture of sodium stearate and styrenated phenol.

[0027] As a further improvement of the present invention, the ACR core monomer is one or a mixture of two of butyl acrylate or ethyl acrylate; the ACR emulsifier is used in a mixture of anionic and non-ionic types; the ACR crosslinking agent is one of divinylbenzene or diallyl phthalate, the ACR initiator is one of ammonium persulfate or potassium persulfate, and the ACR shell monomer is one of methyl methacrylate (MMA) or styrene (St).

[0028] As a further improvement of the present invention, in step 200, by mass percentage, it includes 45 - 55 parts of deionized water, 30 - 40 parts of ACR core monomer, 0.5 - 1.5 parts of ACR emulsifier, 1 - 2 parts of ACR crosslinking agent, 0.1 - 0.5 parts of ACR initiator, and 5 - 20 parts of hexafluoropropylene gas;

[0029] In step 201, by mass percentage, it includes 5 - 15 parts of ACR seed emulsion, 45 - 55 parts of ionic water, 20 - 35 parts of ACR core monomer, 0.5 - 1.5 parts of ACR emulsifier, 1 - 2 parts of ACR crosslinking agent, and 5 - 20 parts of hexafluoropropylene gas.

[0030] As a further improvement of the present invention, in step 202, by mass percentage, it includes 1.5 - 2 parts of ACR emulsifier.

[0031] Advantages of the present invention:

[0032] By using a high-speed centrifuge for centrifugal separation during the preparation of the AIM impact modifier, AIM shell fragments and oligomers can be removed, which can further improve the purity of the obtained AIM impact modifier. At the same time, the AIM shell fragments and oligomers are separated by an ultrafiltration membrane. Since both ACR and AIM are core-shell structured acrylate copolymers, the acrylate oligomers without double bonds in the AIM by-products can be used to improve the weather resistance of PVC products prepared with the ACR impact modifier and avoid degradation caused by ultraviolet rays. Specific embodiments

[0033] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] The present invention provides a preparation method of a high weather-resistant PVC impact modifier, including the preparation of an AIM impact modifier and the preparation of an ACR impact modifier.

[0035] The preparation of the AIM impact modifier is specifically as follows:

[0036] Step 100: Prepare the AIM first core layer emulsion. Control the temperature of the reaction kettle at 50 - 55°C and the rotation speed at 120 - 130 rpm. Add deionized water, AIM first core layer monomers, first core layer emulsifier, first core layer initiator, and first core layer crosslinking agent into the reaction kettle for reaction. After 1.2 - 1.5 h, an AIM first core layer emulsion with an average particle size of 180 - 190 nm is formed.

[0037] Step 101: Prepare the AIM second core layer emulsion. Control the temperature of the high-shear emulsifier at 60 - 65°C and the rotation speed at 3000 - 3200 rpm. Add deionized water, N-methylpyrrolidone, AIM second core layer monomers, second core layer emulsifier, second core layer initiator, and second core layer crosslinking agent into the high-shear emulsifier for reaction. After 0.75 - 1 h, an AIM second core layer emulsion with an average particle size of 125 - 135 nm is formed.

[0038] Step 102: Prepare the AIM inner core mixture. Mix the AIM first core layer emulsion and the AIM second core layer emulsion according to a mass ratio of 10 - 15:20 - 25, and stir at 50 - 55°C for 0.5 - 0.8 hours to form the AIM inner core mixture.

[0039] Step 103: Prepare the AIM shell emulsion. Control the temperature in the reaction kettle at 45 - 50°C and the rotation speed at 80 - 90 rpm. Add deionized water, AIM shell layer monomers, AIM shell layer emulsifier, and AIM shell layer auxiliary agent into the reaction kettle for reaction to form the AIM shell emulsion.

[0040] Step 104: Coating the AIM shell layer on the outer layer of the AIM inner core to form the AIM impact modifier liquid. Mix the AIM inner core mixture and the AIM shell emulsion in the reaction kettle according to a mass ratio of 40 - 45:30 - 35, stir at 45 - 50°C for 2 h, and then cool down to room temperature.

[0041] Step 105: Separate the AIM shell layer fragments with polypropyl methacrylate polymer as the main body and acrylate oligomers in the AIM impact modifier liquid to obtain the AIM impact modifier. The rotation speed of the high-speed centrifuge is between 7000 - 7200 rpm. After centrifugation, sediment for 25 - 30 minutes. Through stratified collection, separate the mixture of AIM shell layer fragments and oligomers in the upper liquid phase from the AIM impact modifier liquid. For the AIM impact modifier liquid from which the mixture of AIM shell layer fragments and oligomers is removed, after cooling, rinse with deionized water and dry to obtain the final AIM impact modifier powder.

[0042] Step 106: Then, separate the acrylate oligomers from the AIM shell layer fragments with polypropyl methacrylate polymer as the main body through a 5 - 20 nm ultrafiltration membrane (such as a Lijun or Koch membrane). The separation end point is determined by the permeate flux dropping to 15% of the initial value.

[0043] As a further explanation of this embodiment, the acrylate oligomer molecules are smaller than the membrane pore size and will pass through the membrane with the solution. The AIM shell layer fragment molecules with polypropyl methacrylate polymer as the main body are larger than the membrane pore size and cannot pass through the membrane pores and are retained. When the ultrafiltration membrane pore size is larger, a small part of the AIM shell layer fragments with smaller molecular sizes will pass through the ultrafiltration membrane.

[0044] In the preparation of the AIM impact modifier, the AIM first core layer monomers are a mixture of n-butyl acrylate (BA) and methyl methacrylate (MMA), and the mass ratio of the two is 60 - 70%: 20 - 30%.

[0045] The first core layer emulsifier is one of sodium dodecyl sulfate (SDS) or polyoxyethylene ether non-ionic emulsifiers, which is used to stabilize the initial emulsion and control the particle size.

[0046] The first core layer initiator is one of ammonium persulfate or APS water-soluble initiators, which ensures slow initiation of free radical polymerization.

[0047] The first core layer cross-linking agent is acrylamide (AM), which is used to enhance the cross-linking degree of the core layer.

[0048] In the preparation of the AIM impact modifier, the AIM second core layer monomers are a mixture of ethyl methacrylate (EMA) and styrene (St), and the mass ratio of the two is 50 - 60%: 30 - 40%.

[0049] The second core layer emulsifier is one of sodium dodecylbenzenesulfonate or a composite emulsification system (such as the compound of SDS and OP-10), which is used to improve the emulsion stability and reduce the particle size to 125 - 135 nm.

[0050] The second core layer initiator is one of an oil-soluble initiator (such as benzoyl peroxide, BPO) or an oxidation-reduction initiator system (such as sodium bisulfite), which is used to increase the reaction rate and control the crosslinking density.

[0051] The second core layer crosslinking agent is acrylamide (AM), which is used to enhance the crosslinking degree of the core layer.

[0052] In the preparation of the AIM impact modifier, the AIM shell monomer is propyl methacrylate, a hard shell material with good compatibility with PVC.

[0053] The AIM shell emulsifier is one of sodium dodecyl sulfate (SDS) or polysorbate, which is used for emulsion stabilization.

[0054] The AIM shell auxiliary agent is a mixture of sodium stearate and styrenated phenol, and the mass ratio of the two is 1:2.

[0055] In step 100, by mass percentage, it includes 60 - 65 parts of deionized water, 30 - 35 parts of the AIM first core layer monomer, 1.5 - 2 parts of the first core layer emulsifier, 1 - 1.5 parts of the first core layer initiator, and 1 - 1.5 parts of the first core layer crosslinking agent.

[0056] In step 101, by mass percentage, it includes 60 - 65 parts of deionized water, 6 - 8 parts of N-methylpyrrolidone, 25 - 30 parts of the AIM second core layer monomer, 1.5 - 2 parts of the second core layer emulsifier, 1 - 1.5 parts of the second core layer initiator, and 1 - 1.5 parts of the second core layer crosslinking agent.

[0057] In step 103, by mass percentage, it includes 65 - 70 parts of deionized water, 25 - 30 parts of the AIM shell monomer, 2 - 2.25 parts of the AIM shell emulsifier, and 0.5 - 0.75 parts of the AIM shell auxiliary agent.

[0058] The preparation of the ACR impact modifier is specifically as follows:

[0059] Step 200: Prepare the ACR seed emulsion. Introduce N2 gas into the closed reactor to displace the air, and then control the reactor pressure to be maintained at 0.2 - 0.6 MPa and the temperature to be maintained at 65 - 80 °C. Add deionized water, the ACR core layer monomer, the ACR emulsifier, the ACR crosslinking agent, and the ACR initiator into the reactor and mix them. At the same time, introduce hexafluoropropylene gas. After the reaction, cool it down to room temperature to obtain the ACR seed emulsion.

[0060] Step 201: Prepare the core layer of ACR particles. Introduce N2 gas into the closed reactor to displace the air, and then control the reactor pressure to be maintained at 0.2 - 0.6 MPa and the temperature at 65 - 80 °C. Add ACR seed emulsion and deionized water into the reactor, and simultaneously introduce hexafluoropropylene gas. Intermittently add ACR core layer monomers, ACR emulsifiers, ACR crosslinkers, and ACR initiators. After mixing and reacting, keep warm at a temperature of 50 - 55 °C for 2.5 - 3.5 h.

[0061] Step 202: Coat the shell layer outside the core layer of ACR particles. Add ACR shell layer monomers, ACR emulsifiers, and the oligomers screened out by the ultrafiltration membrane in Step 106 of the preparation of AIM impact modifier to the product obtained in Step 201, and fully mix and react at 85 - 90 °C. Take out, demulsify, wash with water, and dry to obtain the ACR impact modifier.

[0062] In the preparation of the ACR impact modifier, the ACR core layer monomer is one or a mixture of two of butyl acrylate (BA) or ethyl acrylate (EA). When used in combination, the mass ratio of butyl acrylate (BA) to ethyl acrylate (EA) is 6:4.

[0063] In the preparation of the ACR impact modifier, the ACR emulsifier is a mixture of an anionic type (such as sodium dodecyl sulfate SDS) and a non-ionic type (such as OP-10). When used in combination, the mass ratio of the anionic type (such as sodium dodecyl sulfate SDS) to the non-ionic type (such as OP-10) is 1:1.

[0064] In the preparation of the ACR impact modifier, the ACR crosslinker is one of divinylbenzene (DVB) or diallyl phthalate (DAP).

[0065] In the preparation of the ACR impact modifier, the ACR initiator is one of ammonium persulfate (APS) or potassium persulfate (KPS).

[0066] In the preparation of the ACR impact modifier, the ACR shell layer monomer is one of methyl methacrylate (MMA) or styrene (St).

[0067] In Step 200, by mass percentage, it includes 45 - 55 parts of deionized water, 30 - 40 parts of ACR core layer monomers, 0.5 - 1.5 parts of ACR emulsifiers, 1 - 2 parts of ACR crosslinkers, 0.1 - 0.5 parts of ACR initiators, and 5 - 20 parts of hexafluoropropylene gas.

[0068] In step 201, by mass percentage, it includes 5-15 parts of ACR seed emulsion, 45-55 parts of ionized water, 20-35 parts of ACR core layer monomer, 0.5-1.5 parts of ACR emulsifier, 1-2 parts of ACR crosslinking agent, 0.1-0.5 parts of ACR initiator, and 5-20 parts of hexafluoropropylene gas.

[0069] In step 202, by mass percentage, it includes 60-80 parts of the product obtained in step 201, 18-36 parts of ACR shell layer monomer, 1.5-2 parts of ACR emulsifier, and 2-4 parts of oligomer.

[0070] The present invention will be further described below in conjunction with embodiments.

[0071] Embodiment 1:

[0072] A preparation method of a high weather-resistant PVC impact modifier, specifically:

[0073] Step 100: Prepare the AIM first core layer emulsion, control the temperature of the reaction kettle at 50°C and the rotation speed at 120 rpm. Add 60 parts of deionized water, 30 parts of a mixture of n-butyl acrylate and methyl methacrylate with a mass ratio of 60:20, 1.5 parts of sodium dodecyl sulfate, 1 part of ammonium persulfate, and 1 part of acrylamide into the reaction kettle for reaction. After 1.2 - 1.5 h, an AIM first core layer emulsion with an average particle size of 185 nm is formed.

[0074] Step 101: Prepare the AIM second core layer emulsion, control the temperature of the high-shear emulsifier at 60°C and the rotation speed at 3000 rpm. Add 60 parts of deionized water, 6 parts of N-methylpyrrolidone, 25 parts of a mixture of ethyl methacrylate and styrene with a mass ratio of 50:30, 1.5 parts of sodium dodecylbenzenesulfonate, 1 part of benzoyl peroxide, and 1 part of acrylamide into the high-shear emulsifier for reaction. After 0.75 h, an AIM second core layer emulsion with an average particle size of 125 - 135 nm is formed.

[0075] Step 102: Prepare the AIM inner core mixture, mix the AIM first core layer emulsion and the AIM second core layer emulsion according to a mass ratio of 10:20, and stir at 50°C for 0.5 hour to form the AIM inner core mixture.

[0076] Step 103: Prepare the AIM shell emulsion, control the temperature in the reaction kettle at 45°C and the rotation speed at 80 rpm. Add 65 parts of deionized water, 25 parts of propyl methacrylate, 2 parts of polysorbate, and 0.5 part of a mixture of sodium stearate and styrenated phenol into the reaction kettle for reaction to form the AIM shell emulsion.

[0077] Step 104: Coat the AIM core layer with an AIM shell layer to form an AIM impact modifier liquid. Mix the AIM core mixture and the AIM shell emulsion in a reaction kettle at a mass ratio of 40:30, stir at 45 °C for 2 h, and then cool down to room temperature.

[0078] Step 105: Separate the AIM shell layer fragments mainly composed of acrylate oligomers and poly(propyl methacrylate) in the AIM impact modifier liquid to obtain the AIM impact modifier. Remove the AIM shell layer fragments and oligomers in the AIM impact modifier liquid by a high-speed centrifuge. The rotational speed of the high-speed centrifuge is between 7000 rpm, sediment for 25 min after centrifugation, and separate the mixture of AIM shell layer fragments and oligomers in the upper liquid phase from the AIM impact modifier liquid by stratified collection. The AIM impact modifier liquid after removing the mixture of AIM shell layer fragments and oligomers is cooled, rinsed with deionized water, and dried to obtain the final AIM impact modifier powder.

[0079] Step 106: Separate the AIM shell layer fragments mainly composed of acrylate oligomers and poly(propyl methacrylate) through a 20-nm ultrafiltration membrane (such as a Lilin or Koch membrane). The separation end point is determined when the permeate flux drops to 15% of the initial value.

[0080] Step 200: Prepare an ACR seed emulsion. Introduce N2 gas into a closed reactor to displace the air, and then control the reactor pressure to be maintained at 0.2 MPa and the temperature to be maintained at 65 °C. Add 45 parts of deionized water, 30 parts of a mixture of butyl acrylate and ethyl acrylate, 0.5 part of a mixture of sodium dodecyl sulfate (SDS) and OP-10, 1 part of divinylbenzene, and 0.1 part of potassium persulfate into the reactor and mix them. At the same time, introduce 5 parts of hexafluoropropylene gas. After the reaction, cool down to room temperature to obtain the ACR seed emulsion.

[0081] Step 201: Prepare the core layer of ACR particles. Introduce N2 gas into a closed reactor to displace the air, and then control the reactor pressure to be maintained at 0.2 MPa and the temperature to be maintained at 65 °C. Add 5 parts of the ACR seed emulsion, 45 parts of deionized water into the reactor, introduce 5 parts of hexafluoropropylene gas at the same time, and intermittently add 20 parts of a mixture of butyl acrylate and ethyl acrylate, 0.5 part of a mixture of sodium dodecyl sulfate (SDS) and OP-10, 1 part of divinylbenzene, and 0.1 part of potassium persulfate. After mixing and reacting, keep it warm. The holding temperature is 50 °C and the holding time is 2.5 h.

[0082] Step 202: Coat a shell layer outside the core layer of the ACR particles. Add 18 parts of methyl methacrylate, 1.5 parts of ACR emulsifier, and 2 parts of the oligomer screened out by the ultrafiltration membrane in Step 106 of the preparation of the AIM impact modifier to 60 parts of the product obtained in Step 201, mix and react fully at 85 °C, take it out, demulsify, wash with water, and dry to obtain the ACR impact modifier.

[0083] Example 2:

[0084] According to the same method as in Example 1 for preparing the AIM impact modifier powder, prepare the AIM impact modifier powder, with the difference that when separating the shell layer fragments with acrylate oligomer and poly(propyl methacrylate) as the main body, a 10 nm ultrafiltration membrane (such as a Litree or Koch membrane) is used.

[0085] Step 200: Prepare the ACR seed emulsion. Introduce N2 gas into the closed reactor to displace the air, then control the reactor pressure to be maintained at 0.4 MPa and the temperature to be maintained at 73 °C. Add 50 parts of deionized water, 35 parts of a mixture of butyl acrylate and ethyl acrylate, 1 part of a mixture of sodium dodecyl sulfate SDS and OP-10, 1.5 parts of divinylbenzene, and 0.25 parts of potassium persulfate into the reactor and mix. At the same time, introduce 12.5 parts of hexafluoropropylene gas, and after the reaction, cool to room temperature to obtain the ACR seed emulsion.

[0086] Step 201: Prepare the core layer of the ACR particles. Introduce N2 gas into the closed reactor to displace the air, then control the reactor pressure to be maintained at 0.4 MPa and the temperature to be maintained at 73 °C. Add 10 parts of the ACR seed emulsion, 50 parts of deionized water, and introduce 12.5 parts of hexafluoropropylene gas at the same time. Intermittently add 27.5 parts of a mixture of butyl acrylate and ethyl acrylate, 1 part of a mixture of sodium dodecyl sulfate SDS and OP-10, 1.5 parts of divinylbenzene, and 0.3 parts of potassium persulfate, mix and react, then keep warm, the heat preservation temperature is 53 °C, and the heat preservation time is 3 h.

[0087] Step 202: Coat a shell layer outside the core layer of the ACR particles. Add 27 parts of methyl methacrylate, 1.75 parts of ACR emulsifier, and 3 parts of the oligomer screened out by the ultrafiltration membrane in Step 106 of the preparation of the AIM impact modifier to 70 parts of the product obtained in Step 201, mix and react fully at 88 °C, take it out, demulsify, wash with water, and dry to obtain the ACR impact modifier.

[0088] Example 3:

[0089] The AIM impact modifier powder was prepared in the same manner as in Example 1, except that when separating the acrylate oligomer and the shell fragments mainly composed of poly(propyl methacrylate), a 5-nm ultrafiltration membrane (such as a membrane from Litree or Koch Membrane Systems) was used.

[0090] Step 200: Prepare the ACR seed emulsion. Introduce N2 gas into the closed reactor to displace the air, and then control the reactor pressure to be maintained at 0.6 MPa and the temperature at 80 °C. Add 55 parts of deionized water, 40 parts of a mixture of butyl acrylate and ethyl acrylate, 1.5 parts of a mixture of sodium dodecyl sulfate (SDS) and OP-10, 2 parts of divinylbenzene, and 0.5 parts of potassium persulfate into the reactor and mix them. At the same time, introduce 20 parts of hexafluoropropylene gas. After the reaction, cool it to room temperature to obtain the ACR seed emulsion.

[0091] Step 201: Prepare the core layer of the ACR particles. Introduce N2 gas into the closed reactor to displace the air, and then control the reactor pressure to be maintained at 0.6 MPa and the temperature at 80 °C. Add 15 parts of the ACR seed emulsion, 55 parts of deionized water into the reactor, and introduce 20 parts of hexafluoropropylene gas at the same time. Intermittently add 35 parts of a mixture of butyl acrylate and ethyl acrylate, 1.5 parts of a mixture of sodium dodecyl sulfate (SDS) and OP-10, 2 parts of divinylbenzene, and 0.5 parts of potassium persulfate. After the mixing reaction, keep it warm at a temperature of 55 °C for a holding time of 3.5 h.

[0092] Step 202: Coat the shell layer outside the core layer of the ACR particles. Add 36 parts of methyl methacrylate, 2 parts of the ACR emulsifier, and 4 parts of the oligomer screened out by the ultrafiltration membrane in Step 106 of the preparation of the AIM impact modifier to 80 parts of the product obtained in Step 201. Mix and react fully at 90 °C, then take it out, demulsify, wash with water, and dry to obtain the ACR impact modifier.

[0093] Comparative Example 1: The preparation method of the highly weather-resistant PVC impact modifier described in Example 1 was used, with the difference that: the addition of the oligomer was omitted in Step 202.

[0094] Comparative Example 2: The preparation method of the highly weather-resistant PVC impact modifier described in Example 2 was used, with the difference that: the addition of the oligomer was omitted in Step 202.

[0095] Comparative Example 3: The preparation method of the highly weather-resistant PVC impact modifier described in Example 3 was used, with the difference that: the addition of the oligomer was omitted in Step 202.

[0096] The ACR impact modifiers, polyvinyl chloride (manufacturer: Weifang Shandao Chemical Co., Ltd., model: WELLPREN series PVC) and additives prepared in Examples 1-3 and Comparative Examples 1-3 were proportioned and placed in a mixer to make masterbatch; then the masterbatch was placed in a tablet press, the temperature of the tablet press was set at 180 °C, and then the masterbatch was added to the tablet press and pressed for 10 min to obtain a thin sheet with a thickness of 3 mm. After cooling to room temperature, test specimens were obtained.

[0097] Weather resistance test: According to Method A of Exposure Condition 6.6 in GB / T 16422.3, 2 cycles, test conditions: UVA-340 lamp tube, irradiation for 8 h (blackboard temperature 60 °C), irradiance 0.76 W / m 2 , spraying for 15 min, condensation for 3.75 h (blackboard temperature 50 °C). The color of the material before and after aging was compared, and it was tested once every 100 hours. The total color difference ΔE obtained was taken as the test result. The larger the ΔE value, the greater the color change and the worse the weather resistance of the product. For details, see the comparison table of weather resistance test results in each example and comparative example:

[0098]

[0099] It can be analyzed from the above table that after the high weather-resistant PVC impact modifier containing oligomers is used to modify PVC products, the total color difference ΔE is lower than that of PVC products modified with the conventionally prepared ACR impact modifier, and the weather resistance is significantly improved.

[0100] The above are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above-mentioned implementation measures. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A preparation method of a high weather-resistant PVC impact modifier, characterized in that, The invention comprises the preparation of an AIM impact modifier and the preparation of an ACR impact modifier, wherein the preparation of the AIM impact modifier is as follows: Step 100: preparing an AIM first core layer emulsion; Step 101: preparing an AIM second core layer emulsion; Step 102: Mixing the AIM first core layer emulsion and the AIM second core layer emulsion to form an AIM inner core mixed solution; Step 103: preparing an AIM shell emulsion; Step 104: Mixing the AIM core mixed solution and the AIM shell latex to prepare an AIM impact modifier solution; Step 105: separating the shell fragments mainly composed of propyl methacrylate polymer and acrylate oligomers in the AIM impact modifier liquid by a high-speed centrifuge, and washing them with deionized water and drying them to obtain the final AIM impact modifier powder; Step 106: Separating the shell fragments mainly composed of acrylate oligomers and propyl methacrylate polymers through an ultrafiltration membrane of 5-20 nm, and the separation endpoint is determined by the permeate flow rate dropping to 15% of the initial value; The preparation of ACR impact modifier is specifically as follows: Step 200: adding deionized water, ACR core layer monomer, ACR emulsifier, ACR crosslinker and ACR initiator into a closed reactor and mixing them, while introducing hexafluoropropylene gas, and obtaining ACR seed emulsion after reaction; Step 201: Adding ACR seed emulsion and deionized water into a closed reactor, while introducing hexafluoropropylene gas, and intermittently adding ACR core layer monomer, ACR emulsifier, ACR crosslinking agent, and ACR initiator, mixing and reacting, and then heat preservation to obtain the core layer of the ACR particles; Step 202: Add ACR shell monomer, ACR emulsifier and acrylate oligomer screened out in step 106 of preparing AIM impact modifier to the product obtained in step 201, in the weight percentage, the obtained product is 60-80 parts, ACR shell monomer is 18-36 parts and acrylate oligomer is 2-4 parts. After fully mixing, take out to break the emulsion, wash with water and dry to obtain ACR impact modifier.

2. The preparation method of the high weather-resistant PVC impact modifier according to claim 1, characterized in that, The step 100 specifically comprises adding deionized water, AIM first core layer monomer, first core layer emulsifier, first core layer initiator and first core layer crosslinker into a reaction kettle to react and form an AIM first core layer emulsion; in terms of mass percentage, the emulsion comprises 60-65 parts of deionized water, 30-35 parts of AIM first core layer monomer, 1.5-2 parts of first core layer emulsifier, 1-1.5 parts of first core layer initiator and 1-1.5 parts of first core layer crosslinker.

3. The preparation method of the high weather-resistant PVC impact modifier according to claim 2, characterized in that, The AIM first core layer monomer is a mixture of n-butyl acrylate and methyl methacrylate, the first core layer emulsifier is one of sodium dodecyl sulfate or polyoxyethylene ether non-ionic emulsifier; the first core layer initiator is one of ammonium persulfate or APS water-soluble initiator; the first core layer crosslinker is acrylamide.

4. The preparation method of the high weather-resistant PVC impact modifier according to claim 1, characterized in that, Step 101 specifically involves adding deionized water, N-methylpyrrolidone, the second core layer monomers of AIM, the second core layer emulsifier, the second core layer initiator, and the second core layer crosslinking agent to a high-shear emulsifier for reaction to form the second core layer emulsion of AIM; by mass percentage, 60 - 65 parts of deionized water, 6 - 8 parts of N-methylpyrrolidone, 25 - 30 parts of the second core layer monomers of AIM, 1.5 - 2 parts of the second core layer emulsifier, 1 - 1.5 parts of the second core layer initiator, and 1 - 1.5 parts of the second core layer crosslinking agent.

5. The preparation method of the highly weather-resistant PVC impact modifier according to claim 4, characterized in that, The second core layer monomers of AIM are a mixture of ethyl methacrylate and styrene; the second core layer emulsifier is one of sodium dodecylbenzenesulfonate or a composite emulsification system; the second core layer initiator is one of an oil-soluble initiator or an oxidation-reduction initiation system, and the second core layer crosslinking agent is acrylamide.

6. The preparation method of the high weather-resistant PVC impact modifier according to claim 1, characterized in that, Step 103 specifically involves adding deionized water, the shell layer monomers of AIM, the shell layer emulsifier of AIM, and the shell layer auxiliary agent of AIM to a reaction kettle for reaction to form the shell emulsion of AIM; by mass percentage, 65 - 70 parts of deionized water, 25 - 30 parts of the shell layer monomers of AIM, 2 - 2.25 parts of the shell layer emulsifier of AIM, and 0.5 - 0.75 parts of the shell layer auxiliary agent of AIM.

7. The preparation method of the high weather-resistant PVC impact modifier according to claim 6, characterized in that, The shell layer monomers of AIM are propyl methacrylate; the shell layer emulsifier of AIM is one of sodium dodecyl sulfate or polysorbate; the shell layer auxiliary agent of AIM is a mixture of sodium stearate and styrenated phenol.

8. The preparation method of the high weather-resistant PVC impact modifier according to claim 1, characterized in that, The ACR core layer monomers are one or a mixture of two of butyl acrylate or ethyl acrylate; the ACR emulsifier is used by mixing an anionic type and a non-ionic type; the ACR crosslinking agent is one of divinylbenzene or diallyl phthalate, the ACR initiator is one of ammonium persulfate or potassium persulfate, and the ACR shell layer monomers are one of methyl methacrylate or styrene.

9. The preparation method of the high weather-resistant PVC impact modifier according to claim 1, characterized in that, In step 200, by mass percentage, it includes 45 - 55 parts of deionized water, 30 - 40 parts of ACR core layer monomers, 0.5 - 1.5 parts of ACR emulsifier, 1 - 2 parts of ACR crosslinking agent, 0.1 - 0.5 parts of ACR initiator, and 5 - 20 parts of hexafluoropropylene gas; In step 201, by mass percentage, it includes 5 - 15 parts of ACR seed emulsion, 45 - 55 parts of ionic water, 20 - 35 parts of ACR core layer monomers, 0.5 - 1.5 parts of ACR emulsifier, 1 - 2 parts of ACR crosslinking agent, and 5 - 20 parts of hexafluoropropylene gas.

10. The preparation method of the high weather-resistant PVC impact modifier according to claim 1, characterized in that, In step 202, by mass percentage, it includes 1.5 - 2 parts of ACR emulsifier.

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