Processing aid as well as preparation method and application thereof

Abstract

The invention relates to the field of polyvinyl chloride processing aids, and provides a processing aid and a preparation method and application thereof.The processing aid provided by the invention is especially suitable for being applied in the polyvinyl chloride processing process, can remarkably improve the processing performance of polyvinyl chloride, especially can improve the lubricity and the heat resistance at the same time, and is suitable for popularization and application. The obtained product is flat and smooth in surface. The processing aid is obtained by carrying out emulsion polymerization on a pre-emulsified liquid and an organic barium material liquid in the presence of an initiator and then carrying out dehydration and drying; the pre-emulsion is obtained by pre-emulsifying raw materials including an alkenyl benzene hydrocarbon monomer, an alkenyl nitrile monomer, an emulsifier, a polytetrafluoroethylene emulsion and water in a mass ratio of (69-85.5): (15-30): (1.5-2.4): (3-6): (50-75); the organic barium feed liquid is obtained by reacting raw materials including an alkenyl carboxylic acid monomer, a molecular weight regulator, barium hydroxide and water in a mass ratio of (0.3-0.6): (0.4-0.6): (0.2-0.4): (50-75).

Description

Technical Field

[0001] The present invention relates to the field of polyvinyl chloride processing aids, and particularly relates to a processing aid, a preparation method thereof, and an application thereof. Background Art

[0002] The pure resin of polyvinyl chloride (PVC) has poor thermal stability and poor fluidity during processing. Therefore, it is necessary to add processing aids during the processing to improve its performance. The quality of the aids has an important impact on the processing and forming of PVC products. How to develop a processing aid to facilitate the plasticization of polyvinyl chloride and improve its processing performance, such as improving heat resistance and lubricity, etc., is one of the current technical problems that need to be broken through in this field. Summary of the Invention

[0003] To make up for at least one deficiency of the existing technology, the present invention provides a processing aid, a preparation method thereof, and an application thereof. The processing aid provided by the present invention is particularly suitable for application in the polyvinyl chloride processing process, can significantly improve the processing performance of polyvinyl chloride, especially can take into account the improvement of lubricity and heat resistance, and the obtained product has a smooth surface and high gloss.

[0004] The present invention provides the following technical solutions to achieve its purpose:

[0005] On the one hand, the present invention provides a processing aid, which is obtained by emulsion polymerization of a pre-emulsion and an organic barium liquid in the presence of an initiator, and then dehydration and drying;

[0006] The pre-emulsion is obtained by pre-emulsifying raw materials including an alkenyl benzene hydrocarbon monomer, an alkenyl nitrile monomer, an emulsifier, a polytetrafluoroethylene emulsion, and water with a mass ratio of (69 - 85.5) : (15 - 30) : (1.5 - 2.4) : (3 - 6) : (50 - 75);

[0007] The organic barium liquid is obtained by reacting raw materials including an alkenyl carboxylic acid monomer, a molecular weight regulator, barium hydroxide, and water with a mass ratio of (0.3 - 0.6) : (0.4 - 0.6) : (0.2 - 0.4) : (50 - 75).

[0008] Preferably, the mass ratio of the organic barium liquid to the pre-emulsion is (50.9 - 76.6) : (138.5 - 198.9).

[0009] Preferably, the molecular weight regulator is at least one of isooctyl mercaptoacetate and C10 - C18 alkyl mercaptans;

[0010] And / or, the alkenyl benzene hydrocarbon monomer is at least one of styrene, α-methylstyrene, and phenylpropene;

[0011] And / or, the vinyl cyanide monomer is at least one of acrylonitrile, 3-butenenitrile, and 4-pentenenitrile;

[0012] And / or, the emulsifier is an anionic emulsifier;

[0013] And / or, the vinyl carboxylic acid monomer is selected from at least one of acrylic acid and methacrylic acid;

[0014] And / or, the initiator is selected from at least one of potassium persulfate and ammonium persulfate.

[0015] Preferably, the anionic emulsifier is one or more of sodium dodecyl sulfate and sodium dodecylbenzenesulfonate.

[0016] Preferably, the mass ratio of the vinyl aromatic hydrocarbon monomer to the vinyl cyanide monomer is (72 - 82.5):(15 - 26).

[0017] More preferably, the mass ratio of the vinyl carboxylic acid monomer to the molecular weight regulator is < 1.

[0018] And / or, the mass ratio of the vinyl aromatic hydrocarbon monomer to the vinyl cyanide monomer is (78 - 82):(15 - 20).

[0019] And / or, the vinyl aromatic hydrocarbon monomer is α-methylstyrene.

[0020] The present invention also provides a preparation method of the processing aid described above, including the following steps:

[0021] S1. React the raw materials including the vinyl carboxylic acid monomer, the molecular weight regulator, barium hydroxide, and water by refluxing at 75°C - 90°C to obtain the organic barium liquor;

[0022] S2. Pre-emulsify the raw materials including the vinyl aromatic hydrocarbon monomer, the vinyl cyanide monomer, the emulsifier, polytetrafluoroethylene emulsion, and water under a protective gas atmosphere to obtain the pre-emulsion;

[0023] S3. Add the pre-emulsion to the organic barium liquor by dropwise addition or in multiple steps, and carry out emulsion polymerization in the presence of an initiator to obtain a polymer emulsion;

[0024] S4. Dehydrate and dry the polymer emulsion to obtain the processing aid.

[0025] Preferably, in step S1, the reflux reaction time is 3 - 5 h;

[0026] And / or, in step S2, the pre-emulsification time under the protective gas atmosphere is 0.5 - 1.5 h;

[0027] And / or, the temperature of the pre-emulsification described in step S2 is 15°C - 35°C.

[0028] In some embodiments, in step S3, the initiator is added to the organic barium feed liquid at a temperature of 70°C - 78°C, and the pre-emulsified liquid is added dropwise. The dropping time of the pre-emulsified liquid is 2 - 5 hours. After the dropping is completed, the temperature is raised to 80 - 85°C and kept warm for 1 - 3 hours to obtain the polymer emulsion; wherein, the dosage of the initiator is 0.08% - 0.15% of the total mass of the vinyl aromatic hydrocarbon monomers and the vinyl nitrile monomers.

[0029] Alternatively, in step S3, the pre-emulsified liquid is added to the organic barium feed liquid at a temperature of 70°C - 78°C in 2 - 5 steps, and 0.08% - 0.15% of the initiator of the total mass of the vinyl aromatic hydrocarbon monomers and the vinyl nitrile monomers contained in the pre-emulsified liquid added in each step is added correspondingly when adding the pre-emulsified liquid in each step; after adding the pre-emulsified liquid in each step, the reaction is carried out at 70°C - 78°C for 1 - 2 hours; after all the pre-emulsified liquid is added and the reaction is completed, the temperature is raised to 80 - 85°C and kept warm for 1 - 3 hours to obtain the polymer emulsion.

[0030] The present invention also provides the use of the processing aid described above or the processing aid prepared by the preparation method described above as an aid in the processing of polyvinyl chloride.

[0031] The technical solution provided by the present invention has the following beneficial effects:

[0032] The processing aid provided by the present invention can promote the plasticization of polyvinyl chloride, improve the processing performance of polyvinyl chloride, make polyvinyl chloride more stable during the processing, have good heat resistance and lubricity, and the obtained product has a smooth surface and high gloss. Specific Embodiments

[0033] For the convenience of understanding the present invention, the present invention will be further described below in conjunction with embodiments. It should be understood that the following embodiments are only for better understanding the present invention, and do not mean that the present invention is only limited to the following embodiments.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The term "and / or" that may be used herein includes any and all combinations of one or more of the related listed items.

[0035] The present invention provides a processing aid, which is obtained by dehydrating and drying after emulsion polymerization of a pre-emulsified liquid and an organic barium feed liquid in the presence of an initiator.

[0036] The pre-emulsion is obtained by pre-emulsifying raw materials including alkenyl benzene hydrocarbon monomers, alkenyl nitrile monomers, emulsifiers, polytetrafluoroethylene emulsion and water with a mass ratio of (69 - 85.5):(15 - 30):(1.5 - 2.4):(3 - 6):(50 - 75).

[0037] The organic barium feed liquid is obtained by reacting raw materials including alkenyl carboxylic acid monomers, molecular weight regulators, barium hydroxide and water with a mass ratio of (0.3 - 0.6):(0.4 - 0.6):(0.2 - 0.4):(50 - 75).

[0038] Further, the mass ratio of the organic barium feed liquid to the pre-emulsion is (50.9 - 76.6):(138.5 - 198.9).

[0039] The processing aid of the present invention is obtained by drying after emulsion polymerization of the pre-emulsion and the organic barium feed liquid. The organic barium functional group and polytetrafluoroethylene are introduced simultaneously in the processing aid to play a synergistic role. The obtained processing aid can significantly improve the processing performance of PVC materials during the processing of PVC, make polyvinyl chloride more stable during the processing, can take into account the improvement of heat resistance and lubricity, and the obtained material has a higher glossiness.

[0040] Preferably, the molecular weight regulator is at least one of isooctyl mercaptoacetate and C10 - C18 alkyl mercaptans. More preferably, the molecular weight regulator is isooctyl mercaptoacetate;

[0041] Preferably, the alkenyl benzene hydrocarbon monomers are at least one of styrene, α-methylstyrene, and phenylpropylene. More preferably, it is α-methylstyrene. The inventor has found that when preparing the processing aid, using the preferred α-methylstyrene, the obtained processing aid can further significantly improve the lubricity and heat resistance during the processing of PVC materials.

[0042] Preferably, the alkenyl nitrile monomers are at least one of acrylonitrile, 3-butenenitrile, and 4-pentenenitrile. More preferably, it is acrylonitrile;

[0043] Preferably, the emulsifier is an anionic emulsifier. More preferably, the emulsifier is one or more of sodium dodecyl sulfate and sodium dodecylbenzenesulfonate.

[0044] Preferably, the alkenyl carboxylic acid monomers are selected from at least one of acrylic acid and methacrylic acid. More preferably, it is acrylic acid.

[0045] Preferably, the initiator is selected from at least one of potassium persulfate and ammonium persulfate.

[0046] In a preferred embodiment, the mass ratio of the vinyl aromatic hydrocarbon monomer to the vinyl cyanide monomer is (72 - 82.5):(15 - 26). Using this preferred mass ratio, the processing aid prepared is used for the processing of PVC materials and can better balance excellent heat resistance and glossiness.

[0047] In a more preferred embodiment, the mass ratio of the vinyl carboxylic acid monomer to the molecular weight regulator < 1; the mass ratio of the vinyl aromatic hydrocarbon monomer to the vinyl cyanide monomer is (72 - 82.5):(15 - 26), more preferably (78 - 82):(15 - 20). The inventors have found that when preparing the processing aid, using the above preferred mass ratio, the obtained processing aid can further significantly improve the lubricity and heat resistance improvement effect during the processing of PVC materials.

[0048] In a more preferred embodiment, the vinyl aromatic hydrocarbon monomer is α-methylstyrene, and the mass ratio of the vinyl carboxylic acid monomer to the molecular weight regulator < 1; the mass ratio of the vinyl aromatic hydrocarbon monomer to the vinyl cyanide monomer is (78 - 82):(15 - 20); when the processing aid prepared by this preferred method is applied during the processing of PVC materials, significantly more excellent lubricity and heat resistance improvement effects can be obtained.

[0049] On the other hand, the present invention provides a method for preparing the above-mentioned processing aid, including the following steps:

[0050] S1. React the raw materials including the vinyl carboxylic acid monomer, the molecular weight regulator, barium hydroxide, and water by refluxing at 75°C - 90°C to obtain the organic barium liquid; wherein, the mass ratio of the vinyl carboxylic acid monomer, the molecular weight regulator, barium hydroxide, and water is (0.3 - 0.6):(0.4 - 0.6):(0.2 - 0.4):(50 - 75);

[0051] S2. Pre-emulsify the raw materials including the vinyl aromatic hydrocarbon monomer, the vinyl cyanide monomer, the emulsifier, the polytetrafluoroethylene emulsion, and water at 15°C - 35°C under a protective gas atmosphere to obtain the pre-emulsion; wherein, the mass ratio of the vinyl aromatic hydrocarbon monomer, the vinyl cyanide monomer, the emulsifier, the polytetrafluoroethylene emulsion, and water is (69 - 85.5):(15 - 30):(1.5 - 2.4):(3 - 6):(50 - 75); the protective gas is, for example, nitrogen, etc.;

[0052] S3. Add the pre-emulsion to the organic barium liquid by dropwise addition or in multiple steps, and carry out emulsion polymerization in the presence of an initiator to obtain a polymer emulsion; preferably, the mass ratio of the organic barium liquid to the pre-emulsion is (50.9 - 76.6):(138.5 - 198.9);

[0053] S4. Dehydrate and dry the polymer emulsion to obtain the processing aid.

[0054] In some examples, in step S1, a reflux reaction is carried out, and the main reactions are as follows:

[0055] Ba(OH) 2 + 2HSCH 2 COO-isoC 8 H 17 → Ba(SCH 2 COO-isoC 8 H 17 ) 2 + H 2 O (Equation 1)

[0056] Ba(OH) 2+ CH 2 CHCOOH → (CH 2 CHCOO) 2 Ba + H 2 O (Equation 2)

[0057] In some specific embodiments, in step S1, the time of the reflux reaction is 3 - 5 h;

[0058] In some specific embodiments, in step S2, the time for pre-emulsification under the protective gas atmosphere is 0.5 - 1.5 h.

[0059] In some specific embodiments, in step S3, the pre-emulsion is fed in a dropwise manner; specifically, in step S3, the initiator is added to the organic barium feed liquid at a temperature of 70°C - 78°C, and the pre-emulsion is added dropwise. The dropping time of the pre-emulsion is 2 - 5 hours. After the dropping is completed, the temperature is raised to 80 - 85°C and kept warm for 1 - 3 h to obtain the polymer emulsion; wherein, the dosage of the initiator is 0.08% - 0.15% of the total mass of the vinyl aromatic hydrocarbon monomers and the vinyl nitrile monomers;

[0060] In some other specific embodiments, the pre-emulsion liquid described in step S3 is fed in a multi-step manner; specifically, in step S3, the pre-emulsion liquid is added to the organic barium feed liquid at a temperature of 70°C - 78°C in 2 - 5 steps; and when adding the pre-emulsion liquid in each step, 0.08% - 0.15% of the initiator contained in the vinylbenzene hydrocarbons monomers and the vinylnitrile monomers in the pre-emulsion liquid added in this step is correspondingly added; after adding the pre-emulsion liquid in each step, the reaction is carried out at 70°C - 78°C for 1 - 2 h; after all the pre-emulsion liquid is added and the reaction is completed, the temperature is raised to 80 - 85°C and kept warm for 1 - 3 h to obtain the polymer emulsion. Preferably, the pre-emulsion liquid is evenly divided into 2 - 5 portions, and one portion is added in each step during the stepwise addition; more preferably, the pre-emulsion liquid is evenly divided into 3 portions and added in 3 steps.

[0061] More preferably, the pre-emulsion liquid described in step S3 is fed in a multi-step manner; the inventors have found that when the pre-emulsion liquid is fed in a multi-step manner, compared with the dropping method, the processing aid prepared and applied in the processing of PVC materials not only has improved heat resistance, but also has significantly better gloss.

[0062] Preferably, the initiator is selected from at least one of potassium persulfate and ammonium persulfate, and more preferably potassium persulfate.

[0063] On the other hand, the present invention provides the application of the processing aid described above or the processing aid prepared by the preparation method described above as an aid in the processing of polyvinyl chloride. Preferably, the present invention provides the application of the processing aid as an aid in the processing of polyvinyl chloride for improving the surface gloss and / or heat resistance of polyvinyl chloride products.

[0064] The following further illustrates the solution of the present invention through examples, but it should not be understood that the present invention is only limited thereto.

[0065] 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 or instruments not specifying the manufacturers, they are all conventional products that can be obtained through commercial purchase.

[0066] <Sources of some raw materials used in the following examples and comparative examples>

[0067] Polytetrafluoroethylene emulsion: Model 4DC - A1 of Hangzhou Jingfu Technology Co., Ltd.;

[0068] Sodium dodecyl sulfate: Kao Corporation of Japan;

[0069] Sodium dodecylbenzenesulfonate: Kao Corporation of Japan;

[0070] Potassium persulfate: Shandong Xiya Chemical Co., Ltd.;

[0071] Isooctyl thioglycolate: Shandong Chuangying Chemical Co., Ltd.;

[0072] Styrene: Zibo Junchen New Material Technology Co., Ltd.;

[0073] α-Methylstyrene: Zibo Junchen New Material Technology Co., Ltd.;

[0074] Acrylonitrile: Shandong Keluer Chemical Co., Ltd.;

[0075] Acrylic acid: Shandong Taiyang Chemical Co., Ltd.;

[0076] Barium hydroxide: Nantong Runfeng Petrochemical Co., Ltd.;

[0077] PVC (K57), Qilu Petrochemical;

[0078] Heavy calcium carbonate, Qingzhou Yuxin Calcium Industry Co., Ltd.;

[0079] Calcium / zinc stabilizer RH-915, Shandong Ruihe New Material Co., Ltd.;

[0080] Oxidized polyethylene wax Luwax OA2, BASF Group;

[0081] Pentaerythritol stearate DN-PETS, Shandong Dawn Group Co., Ltd.;

[0082] Polyethylene wax DN-1, Shandong Dawn Group Co., Ltd.

[0083] <Test method>

[0084] Vicat softening point: Determination of Vicat softening temperature (VST) of thermoplastics - GB / T 1633-2000;

[0085] Surface glossiness: 60° glossiness meter.

[0086] Example 1

[0087] Prepare processing aids according to the following steps:

[0088] S1. Preparation of organic barium liquor: Put the above raw materials into the reaction kettle according to the mass ratio of acrylic acid (CH 2 CHCOOH): isooctyl thioglycolate (HSCH 2 COO-isoC 8 H 17 ): barium hydroxide (Ba(OH) 2 ): water of 0.4:0.5:0.3:70, and reflux and react at 80 °C for 3 h to obtain organic barium liquor.

[0089] S2. Preparation of pre-emulsion: Styrene, acrylonitrile, sodium dodecylbenzenesulfonate, polytetrafluoroethylene emulsion, and water were mixed at a mass ratio of 81:16.5:1.8:4.5:50 and pre-emulsified at 30°C for 1 h under a nitrogen atmosphere to obtain a pre-emulsion.

[0090] The mass of the organic barium feed liquid obtained in step S1 was a, and the mass of the pre-emulsion obtained in step S2 was b, with a:b = 71.2:153.8. The feeding for step S3 was carried out according to this mass ratio.

[0091] S3. After pre-emulsification, the shell layer was prepared by a stepwise addition method. The temperature of the organic barium feed liquid (used as the core layer emulsion) obtained in step S1 was adjusted to 75°C, and the pre-emulsion obtained in step S2 was evenly divided into 3 steps and added to the organic barium feed liquid; for each step of adding the pre-emulsion, an initiator (potassium persulfate) was added accordingly, and the addition amount of the initiator was 0.1% of the total mass of styrene and acrylonitrile monomers in the pre-emulsion added in this step. After each step of adding the pre-emulsion, the reaction was carried out at 75°C for 1 h. After all the pre-emulsion was added and the reaction was completed, the temperature was raised to 80°C and kept warm for 2 h to obtain a processing aid emulsion.

[0092] S4. Spray drying: The processing aid emulsion was spray-dried to obtain the processing aid of Example 1.

[0093] Example 2

[0094] The processing aid was prepared according to the following steps:

[0095] S1. Preparation of organic barium feed liquid: Acrylic acid (CH 2 CHCOOH), isooctyl mercaptoacetate (HSCH 2 COO-isoC 8 H 17 ), barium hydroxide (Ba(OH) 2 ), and water were charged into the reaction kettle at a mass ratio of 0.4:0.5:0.3:70, and the above raw materials were refluxed and reacted at 80°C for 3 h to obtain an organic barium feed liquid.

[0096] S2. Preparation of pre-emulsion: α-Methylstyrene, acrylonitrile, sodium dodecylbenzenesulfonate, polytetrafluoroethylene emulsion, and water were mixed at a mass ratio of 81:16.5:1.8:4.5:50 and pre-emulsified at 30°C for 1 h under a nitrogen atmosphere to obtain a pre-emulsion.

[0097] The mass of the organic barium feed liquid obtained in step S1 was a, and the mass of the pre-emulsion obtained in step S2 was b, with a:b = 71.2:153.8. The feeding for step S3 was carried out according to this mass ratio.

[0098] S3. After pre-emulsification is completed, the shell layer is prepared by the method of stepwise addition. Adjust the temperature of the organic barium feed liquid (used as the core layer emulsion) obtained in step S1 to 75 °C, and divide the pre-emulsion liquid obtained in step S2 into three steps and add it to the organic barium feed liquid; when adding the pre-emulsion liquid in each step, add the initiator (potassium persulfate) accordingly, and the addition amount of the initiator is 0.1% of the total mass of α-methylstyrene and acrylonitrile monomers in the pre-emulsion liquid added in this step. After adding the pre-emulsion liquid in each step, react at 75 °C for 1 h. After all the pre-emulsion liquid is added and the reaction is completed, raise the temperature to 80 °C and keep it warm for 2 h to obtain the processing aid emulsion.

[0099] S4. Spray drying: The processing aid emulsion is spray-dried to obtain the processing aid of Example 2.

[0100] Example 3

[0101] The processing aid is prepared according to the following steps:

[0102] S1. Preparation of the organic barium feed liquid: According to the mass ratio of acrylic acid (CH 2 CHCOOH): isooctyl mercaptoacetate (HSCH 2 COO-isoC 8 H 17 ): barium hydroxide (Ba(OH) 2 ) : water is 0.5:0.4:0.3:70, put the above raw materials into the reaction kettle, and reflux and react at 80 °C for 3 h to obtain the organic barium feed liquid.

[0103] S2. Preparation of the pre-emulsion liquid: Styrene, acrylonitrile, sodium dodecylbenzenesulfonate, polytetrafluoroethylene emulsion, and water are in a mass ratio of 81:16.5:1.8:4.5:50, and pre-emulsify at 30 °C for 1 h under a nitrogen atmosphere to obtain the pre-emulsion liquid.

[0104] The mass of the organic barium feed liquid obtained in step S1 is a, and the mass of the pre-emulsion liquid obtained in step S2 is b, a:b = 71.2:153.8, and the feeding in step S3 is carried out according to this mass ratio.

[0105] S3. After pre-emulsification is completed, the shell layer is prepared by the method of stepwise addition. Adjust the temperature of the organic barium feed liquid (used as the core layer emulsion) obtained in step S1 to 75 °C, and divide the pre-emulsion liquid obtained in step S2 into three steps and add it to the organic barium feed liquid; when adding the pre-emulsion liquid in each step, add the initiator (potassium persulfate) accordingly, and the addition amount of the initiator is 0.1% of the total mass of styrene and acrylonitrile monomers in the pre-emulsion liquid added in this step. After adding the pre-emulsion liquid in each step, react at 75 °C for 1 h. After all the pre-emulsion liquid is added and the reaction is completed, raise the temperature to 80 °C and keep it warm for 2 h to obtain the processing aid emulsion.

[0106] S4. Spray drying: The processing aid emulsion is spray-dried to obtain the processing aid of Example 3.

[0107] Example 4

[0108] The processing aid is prepared according to the following steps:

[0109] S1. Preparation of the organic barium liquor: According to the mass ratio of acrylic acid (CH 2 CHCOOH): isooctyl mercaptoacetate (HSCH 2 COO-isoC 8 H 17 ): barium hydroxide (Ba(OH) 2 ): water being 0.4:0.5:0.3:70, the above raw materials are put into the reaction kettle, and reflux reaction is carried out at 80 °C for 3 h to obtain the organic barium liquor.

[0110] S2. Preparation of the pre-emulsion: Styrene, acrylonitrile, sodium dodecylbenzenesulfonate, polytetrafluoroethylene emulsion, and water are in a mass ratio of 72:25.5:1.8:4.5:50, and pre-emulsification is carried out at 30 °C for 1 h under a nitrogen atmosphere to obtain the pre-emulsion.

[0111] The mass of the organic barium liquor obtained in step S1 is a, and the mass of the pre-emulsion obtained in step S2 is b, a:b = 71.2:153.8, and feeding for step S3 is carried out according to this mass ratio.

[0112] S3. After pre-emulsification is completed, the shell layer is prepared by a stepwise addition method. The temperature of the organic barium liquor obtained in step S1 (as the core layer emulsion) is adjusted to 75 °C, and the pre-emulsion obtained in step S2 is evenly divided into 3 steps and added to the organic barium liquor; for each step when adding the pre-emulsion, an initiator (potassium persulfate) is correspondingly added, and the addition amount of the initiator is 0.1% of the total mass of styrene and acrylonitrile monomers in the pre-emulsion added in this step. After adding the pre-emulsion in each step, reaction is carried out at 75 °C for 1 h. After all the pre-emulsion is added and the reaction is completed, the temperature is raised to 80 °C and kept warm for 2 h to obtain the processing aid emulsion.

[0113] S4. Spray drying: The processing aid emulsion is spray-dried to obtain the processing aid of Example 4.

[0114] Example 5

[0115] The processing aid is prepared according to the following steps:

[0116] S1. Preparation of the organic barium liquor: According to the mass ratio of acrylic acid (CH 2 CHCOOH): isooctyl mercaptoacetate (HSCH 2 COO-isoC 8 H 17) Barium hydroxide (Ba(OH) 2 ) The mass ratio of water is 0.4:0.5:0.3:70. Add the above raw materials into the reaction kettle and reflux at 80 °C for 3 h to obtain an organic barium liquid material.

[0117] S2. Preparation of pre-emulsion: Styrene, acrylonitrile, sodium dodecylbenzenesulfonate, polytetrafluoroethylene emulsion, and water are pre-emulsified at 30 °C for 1 h under a nitrogen atmosphere according to the mass ratio of 81:16.5:1.8:4.5:50 to obtain a pre-emulsion.

[0118] The mass of the organic barium liquid material obtained in step S1 is a, and the mass of the pre-emulsion obtained in step S2 is b, a:b = 71.2:153.8. Feed in step S3 according to this mass ratio.

[0119] S3. After pre-emulsification, the shell layer is prepared by a stepwise addition method. Adjust the temperature of the organic barium liquid material (as the core layer emulsion) obtained in step S1 to 75 °C, and add the pre-emulsion obtained in step S2 dropwise into the organic barium liquid material; the addition amount of the initiator (potassium persulfate) is 0.1% of the total mass of styrene and acrylonitrile monomers in the pre-emulsion added in this step. The initiator is added in two times, half of the initiator is added before the start of dropping, and the remaining half of the initiator is added after half of the pre-emulsion is dropped. The dropping time of the pre-emulsion is 3 h, and after the dropping is completed, continue to react for 1 h. After the reaction is completed, raise the temperature to 80 °C and keep warm for 2 h to obtain a processing aid emulsion.

[0120] S4. Spray drying: The processing aid emulsion is spray-dried to obtain the processing aid of Example 5.

[0121] Example 6

[0122] Prepare the processing aid according to the following steps:

[0123] S1. Preparation of organic barium liquid material: According to acrylic acid (CH 2 CHCOOH): isooctyl mercaptoacetate (HSCH 2 COO-isoC 8 H 17 ) Barium hydroxide (Ba(OH) 2 ) The mass ratio of water is 0.4:0.5:0.3:70. Add the above raw materials into the reaction kettle and reflux at 80 °C for 3 h to obtain an organic barium liquid material.

[0124] S2. Preparation of pre-emulsion: Styrene, acrylonitrile, sodium dodecylbenzenesulfonate, polytetrafluoroethylene emulsion, and water are pre-emulsified at 30 °C for 1 h under a nitrogen atmosphere according to the mass ratio of 69:30:1.8:4.5:50 to obtain a pre-emulsion.

[0125] The mass of the organic barium feed liquid obtained in step S1 is a, and the mass of the pre-emulsion obtained in step S2 is b, where a:b = 71.2:153.8. The feeding in step S3 is carried out according to this mass ratio.

[0126] S3. After pre-emulsification is completed, the shell layer is prepared by a method of stepwise addition. The temperature of the organic barium feed liquid (used as the core layer emulsion) obtained in step S1 is adjusted to 75 °C, and the pre-emulsion obtained in step S2 is evenly divided into 3 steps and added to the organic barium feed liquid; when adding the pre-emulsion in each step, an initiator (potassium persulfate) is correspondingly added, and the addition amount of the initiator is 0.1% of the total mass of styrene and acrylonitrile monomers in the pre-emulsion added in this step. After adding the pre-emulsion in each step, the reaction is carried out at 75 °C for 1 h. After all the pre-emulsion is added and the reaction is completed, the temperature is raised to 80 °C and kept warm for 2 h to obtain a processing aid emulsion.

[0127] S4. Spray drying: The processing aid emulsion is spray-dried to obtain the processing aid of Example 6.

[0128] Comparative Example 1

[0129] It is carried out with reference to Example 1, except that: barium hydroxide (Ba(OH) 2 ) is not added in step S1.

[0130] Comparative Example 2

[0131] It is carried out with reference to Example 1, except that: polytetrafluoroethylene emulsion is not added in step S2.

[0132] Comparative Example 3

[0133] It is carried out with reference to Example 1, except that: barium hydroxide (Ba(OH) 2 ) is not added in step S1, and polytetrafluoroethylene emulsion is not added in step S2.

[0134] Comparative Example 4

[0135] It is carried out with reference to Example 1, except that: in step S1, the mass ratio of acrylic acid (CH 2 CHCOOH): isooctyl mercaptoacetate (HSCH 2 COO-isoC 8 H 17 ): barium hydroxide (Ba(OH) 2 ): water is 0.4:0.5:0.1:70; in step S2, the mass ratio of styrene, acrylonitrile, emulsifier sodium dodecylbenzenesulfonate, polytetrafluoroethylene emulsion, and water is 81:16.5:1.8:1.5:50.

[0136] Application performance detection:

[0137] The processing aids obtained from the above-mentioned examples and comparative examples were used for the processing of PVC materials. The preparation method of the PVC materials was as follows: The raw materials were mixed in a high-speed mixer to 110 °C, then cooled to 44 °C and discharged; the mixed raw materials were all passed through a 40-mesh sieve, and then melted and plasticized by a twin-screw extruder, extruded, shaped and cooled, cut, and the finished products were packaged.

[0138] Among them, the extrusion process conditions were as follows:

[0139] Barrel temperature: 178 - 185 °C;

[0140] Motor speed: 40 rpm;

[0141] Feeding speed: 1000 rpm;

[0142] Traction speed 500 rpm.

[0143] The raw material formula of the PVC materials is shown in Table 1.

[0144] Table 1

[0145] Raw materials Dosage (parts by mass) PVC (K57, polyvinyl chloride) 80 Heavy calcium carbonate 70 Calcium-zinc stabilizer 4 Oxidized polyethylene wax 0.5 Pentaerythritol stearate 0.8 PE wax (i.e., polyethylene wax) 0.4 Processing aid 1.0

[0146] Among them, the processing aids in Table 1 were the processing aids prepared from the above-mentioned examples and comparative examples. That is, the processing aids prepared in the above-mentioned examples and comparative examples were used for the processing of PVC materials according to the formula in Table 1 respectively, and the obtained PVC materials were subjected to relevant performance tests. The specific test results are shown in Table 2 below.

[0147] Table 2

[0148] Item Vicat softening point, °C Surface gloss, GU Example 1 91.2 83.5 Example 2 92.5 84.0 Example 3 90.8 82.1 Example 4 90.5 81.5 Example 5 91.1 80.8 Example 6 90 80.7 Comparative Example 1 87.4 80.5 Comparative Example 2 89.6 79.2 Comparative Example 3 85.7 77.5 Comparative Example 4 88.5 80.1

[0149] As can be seen from the above experimental results, compared with Comparative Examples 1-4, the processing aids provided in the embodiments of the present invention can significantly improve the heat resistance and lubricity when applied in the processing of PVC materials, and the obtained products have higher gloss. Compared with other embodiments, in Example 6, the mass ratio of the vinylbenzene hydrocarbon monomer to the vinylnitrile monomer does not conform to the preferred mass ratio of (72-82.5):(15-26). Based on the obtained processing aids for PVC material processing, it is inferior to other embodiments in terms of both heat resistance and gloss. Compared with Examples 3 and 4, in Example 1, the processing aids prepared with a mass ratio of acrylic acid to isooctyl mercaptoacetate >1 and a more preferred mass ratio of styrene to acrylonitrile can further improve the heat resistance of the PVC material and the surface gloss of the obtained products. Compared with Example 1, in Example 5, the processing aids prepared by the dropping reaction process also have improved heat resistance, but the gloss is significantly inferior to that of Example 1. Compared with Example 1, in Example 2, the preferred α-methylstyrene is further used in the pre-emulsion, and more excellent heat resistance can be obtained, and the obtained products have better surface gloss.

[0150] It is easily understandable that the above embodiments are merely examples for clear illustration and do not mean that the present invention is limited thereto. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A processing aid, characterized in that: The processing aid is obtained by emulsion polymerization of a pre-emulsified liquid and an organic barium liquid in the presence of an initiator, followed by dehydration and drying; The pre-emulsion is prepared by pre-emulsifying raw materials including alkenylbenzene hydrocarbon monomer, alkenyl nitrile monomer, emulsifier, polytetrafluoroethylene emulsion and water in a mass ratio of (69-85.5): (15-30): (1.5-2.4): (3-6): (50-75); The organic barium liquid is obtained by reacting raw materials including alkenyl carboxylic acid monomers, a molecular weight regulator, barium hydroxide and water in a mass ratio of (0.3-0.6): (0.4-0.6): (0.2-0.4): (50-75).

2. The processing aid according to claim 1, characterized in that The mass ratio of the organic barium liquid to the pre-emulsion liquid is (50.9-76.6):(138.5-198.9).

3. The processing aid according to claim 1 or 2, characterized in that The molecular weight regulator is at least one of isooctyl thioglycolate and C10-C18 alkyl mercaptan; And / or, the alkenylbenzene hydrocarbon monomer is at least one of styrene, α-methylstyrene, and styrene propene; And / or, the alkenyl nitrile monomer is at least one of acrylonitrile, 3-butenenitrile and 4-pentenenitrile; And / or, the emulsifier is an anionic emulsifier; And / or, the alkenyl carboxylic acid monomer is at least one selected from acrylic acid and methacrylic acid; And / or, the initiator is selected from at least one of potassium persulfate and ammonium persulfate.

4. The processing aid according to claim 3, characterized in that The anionic emulsifier is one or more of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

5. The processing aid according to claim 1 or 2, characterized in that: The mass ratio of the alkenylbenzene hydrocarbon monomer to the alkenyl nitrile monomer is (72-82.5):(15-26).

6. The processing aid according to claim 5, characterized in that The mass ratio of the alkenyl carboxylic acid monomer to the molecular weight regulator is less than 1; and / or, the mass ratio of the alkenylbenzene hydrocarbon monomer to the alkenyl nitrile monomer is (78-82):(15-20); And / or, the alkenylbenzene hydrocarbon monomer is α-methylstyrene.

7. The method for preparing the processing aid according to any one of claims 1 to 6, characterized in that: The steps include: S1, subjecting the raw materials including the alkenyl carboxylic acid monomer, the molecular weight regulator, barium hydroxide and water to reflux reaction at 75° C.-90° C. to obtain the organic barium liquid; S2, pre-emulsifying the raw materials including the alkenylbenzene hydrocarbon monomer, the alkenyl nitrile monomer, the emulsifier, the polytetrafluoroethylene emulsion and water under a protective gas atmosphere to obtain the pre-emulsified liquid; S3, adding the pre-emulsion into the organic barium liquid by dropwise addition or multi-step addition, and performing emulsion polymerization in the presence of an initiator to obtain a polymer emulsion; S4, dehydrating and drying the polymer emulsion to obtain the processing aid.

8. The preparation method according to claim 7, characterized in that: In step S1, the reflux reaction time is 3-5h; And / or, in step S2, the pre-emulsification is performed under the protective gas atmosphere for 0.5-1.5 h; And / or, the pre-emulsification temperature in step S2 is 15°C-35°C.

9. The preparation method according to claim 7, characterized in that: In step S3, the initiator is added to the organic barium liquid at a temperature of 70° C.-78° C., and the pre-emulsion is added by dropwise addition, and the dropwise addition time of the pre-emulsion is 2-5 hours. After the dropwise addition is completed, the temperature is raised to 80-85° C. and kept warm for 1-3 hours to obtain the polymer emulsion; wherein the amount of the initiator is 0.08%-0.15% of the total mass of the alkenyl benzene hydrocarbon monomer and the alkenyl nitrile monomer; Alternatively, in step S3, the pre-emulsion is added to the organic barium liquid at a temperature of 70°C-78°C in 2-5 steps, and when the pre-emulsion is added in each step, 0.08%-0.15% of the initiator is added accordingly based on the total mass of the alkenylbenzene hydrocarbon monomer and the alkenyl nitrile monomer contained in the pre-emulsion added in that step; after each step of adding the pre-emulsion, the reaction is carried out at 70°C-78°C for 1-2h; after all the pre-emulsions are added and the reaction is completed, the temperature is raised to 80-85°C and kept warm for 1-3h to obtain the polymer emulsion.

10. Use of the processing aid according to any one of claims 1 to 6 or the processing aid prepared by the preparation method according to any one of claims 7 to 9 as an aid in the processing of polyvinyl chloride.