Foaming regulator aid as well as preparation method and application thereof

Abstract

The invention relates to the field of foaming regulator aids, and provides a foaming regulator aid as well as a preparation method and application thereof. The foaming regulator auxiliary agent is beneficial to dispersion of the foaming regulator, and a foaming material with low density and good thermal stability can be obtained. The foaming regulator auxiliary agent is obtained by carrying out emulsion polymerization on a shell layer pre-emulsion and a core layer emulsion in the presence of a first initiator and then carrying out dehydration and drying; the raw materials of the shell layer comprise alkyl methacrylate monomers, organic barium feed liquid, a first cross-linking agent, a molecular weight regulator, a first emulsifier and water in a mass ratio of (60-75): (10-25): (1.5-2.7): (3.0-5.4): (0.9-1.8): (15-24); the core layer is prepared from the following raw materials: an alkyl acrylate monomer, an alkyl methacrylate monomer, a second cross-linking agent, a second emulsifier and water in a mass ratio of (20-30): (5-10): (0.2-0.5): (0.3-0.6): (250-300).

Description

Technical Field

[0001] The present invention relates to the field of foaming regulator auxiliaries, and particularly to a foaming regulator auxiliary, a preparation method thereof and an application thereof. Background Art

[0002] Foamed materials meet the lightweight requirements. Lightweight materials have become a key area for the development of new materials in China, and foaming is the most direct means to achieve polymer lightweighting. The green preparation of high-quality foamed materials has always been a hot spot and a difficult point in the field of polymer foaming. During the processing of PVC materials, the melt strength is limited. In the case of high foaming ratios, it is easy to cause relatively large and uneven cell diameters, resulting in a problem of relatively high foaming density. Currently, the most effective way is to add high-molecular-weight foaming regulators. The principle is that the long molecular chains of the foaming regulators are entangled with the PVC molecular chains, increasing the number of entanglement points, thereby improving the melt strength, facilitating the encapsulation of air bubbles, preventing cell collapse, and obtaining products with lower density. However, due to the limitation of the relatively low thermal decomposition temperature of the mainstream acrylate foaming regulators, their application range is relatively narrow. Summary of the Invention

[0003] To make up for at least one deficiency existing in the prior art, the present invention provides a foaming regulator auxiliary, a preparation method thereof and an application thereof. During the processing of PVC materials and the like using a foaming regulator, simultaneously using the foaming regulator auxiliary of the present invention is beneficial to the dispersion of the foaming regulator, and a foamed material with both low density and good thermal stability can be obtained.

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

[0005] On the one hand, the present invention provides a foaming regulator auxiliary, which is obtained by emulsion polymerization of a shell pre-emulsion and a core emulsion in the presence of a first initiator, followed by dehydration and drying;

[0006] The shell pre-emulsion is obtained by pre-emulsifying shell raw materials, and the shell raw materials include alkyl methacrylate monomers, organic barium liquid, a first cross-linking agent, a molecular weight regulator, a first emulsifier and water with a mass ratio of (60 - 75):(10 - 25):(1.5 - 2.7):(3.0 - 5.4):(0.9 - 1.8):(15 - 24);

[0007] The core emulsion is obtained by reacting a pre-emulsion of core raw materials in the presence of a second initiator, and the core raw materials include alkyl acrylate monomers, alkyl methacrylate monomers, a second cross-linking agent, a second emulsifier and water with a mass ratio of (20 - 30):(5 - 10):(0.2 - 0.5):(0.3 - 0.6):(250 - 300);

[0008] The molecular weight regulator in the shell layer raw material is selected from at least one of isooctyl thioglycolate and alkyl mercaptans with C10-C18.

[0009] Preferably, the alkyl groups in the methacrylic acid alkyl ester monomers in the shell layer raw material and the core layer raw material are independently straight-chain alkyl groups with C1-C6 or branched-chain alkyl groups with C1-C8 respectively. The number of carbon atoms in the alkyl groups in the methacrylic acid alkyl ester monomers is, for example, 1, 2, 3, 4, 5, 6, 7, 8;

[0010] And / or, the alkyl group in the acrylic acid alkyl ester monomer is a straight-chain alkyl group with C1-C6 or a branched-chain alkyl group with C1-C8, and the number of carbon atoms in the alkyl group in the acrylic acid alkyl ester monomer is, for example, 1, 2, 3, 4, 5, 6, 7, 8;

[0011] And / or, the first crosslinking agent and the second crosslinking agent are independently selected from at least one of allyl methacrylate, allyl acrylate, divinylbenzene, trimethylolpropane triacrylate, and 3-(propoxy)propane triacrylate;

[0012] And / or, the first emulsifier and the second emulsifier are independently selected from anionic emulsifiers;

[0013] And / or, the first initiator and the second initiator are independently selected from at least one of potassium persulfate and ammonium persulfate;

[0014] And / or, the organic barium feed liquid is one or both of barium acrylate feed liquid and barium methacrylate feed liquid.

[0015] Preferably, the anionic emulsifier is selected from at least one of potassium fatty acid soap, alkyl sulfates, and alkyl benzene sulfonates.

[0016] Preferably, the preparation steps of the organic barium feed liquid include: refluxing and condensing a raw material including barium carbonate, raw material A, and water with a mass ratio of 1:(1-1.2):(10-20) at 70-90 °C for 1-2 h; the raw material A is selected from acrylic acid and / or methacrylic acid.

[0017] Preferably, the mass ratio of the core layer emulsion to the total mass of the shell layer raw material is (275-342):(90.4-134.1).

[0018] More preferably, the shell layer raw material includes a methacrylic acid alkyl ester monomer, an organic barium feed liquid, a first crosslinking agent, a molecular weight regulator, a first emulsifier, and water with a mass ratio of (70-75):(12-20):(2.0-2.4):(3.0-5.4):(0.9-1.8):(15-24);

[0019] The core layer raw materials include an acrylic alkyl ester monomer, a methacrylic acid alkyl ester monomer, a second crosslinking agent, a second emulsifier, and water in a mass ratio of (24 - 27):(5 - 10):(0.2 - 0.5):(0.3 - 0.6):(250 - 300);

[0020] The acrylic alkyl ester monomer is n-butyl acrylate;

[0021] The molecular weight regulator is isooctyl thioglycolate.

[0022] The present invention also provides a preparation method of the foaming regulator auxiliary agent described above, including the following steps:

[0023] S1. Prepare the core layer emulsion: Put the core layer raw materials into a reaction kettle, pre-emulsify at a temperature of 15°C - 35°C under a protective gas atmosphere to obtain a pre-emulsion, then raise the temperature to 70°C - 78°C, add the second initiator, and react at 70°C - 78°C for 3 - 5 hours under a protective gas atmosphere, and then raise the temperature to 80°C - 85°C and keep warm for 1 - 2 hours to obtain the core layer emulsion;

[0024] S2. Pre-emulsify the shell layer raw materials at a temperature of 15°C - 35°C under a protective gas atmosphere to obtain the shell layer pre-emulsion, and then feed it into the core layer emulsion by dropping or adding in multiple steps, and carry out emulsion polymerization in the presence of the first initiator to obtain a polymer emulsion;

[0025] S3. Dehydrate and dry the polymer emulsion to obtain the foaming regulator auxiliary agent.

[0026] Preferably, in step S1, the pre-emulsification time is 0.5 - 1.5 hours;

[0027] And / or, in step S2, the pre-emulsification time is 0.5 - 1.5 hours;

[0028] And / or, in step S1, the dosage of the second initiator is 0.08% - 0.15% of the total mass of the acrylic alkyl ester monomer and the methacrylic acid alkyl ester monomer in the core layer raw materials.

[0029] Preferably, in step S2, the shell layer pre-emulsion is fed into the core layer emulsion at a temperature of 70°C - 78°C by dropping, and the reaction is carried out in the presence of the first initiator; the dropping time of the shell layer pre-emulsion is 2 - 5 hours, and after dropping, the temperature is raised to 80 - 85°C and kept warm for 1 - 3 hours to obtain the polymer emulsion; the dosage of the first initiator is 0.08% - 0.15% of the mass of the methacrylic acid alkyl ester monomer contained in the shell layer pre-emulsion;

[0030] Alternatively, in step S2, the shell pre-emulsion is added to the core emulsion at a temperature of 70°C to 78°C in 2 to 5 steps. When adding the shell pre-emulsion in each step, the first initiator with a mass of 0.08% to 0.15% of the mass of the alkyl methacrylate monomer contained in the shell pre-emulsion added in that step is added correspondingly. After adding the shell pre-emulsion in each step, the reaction is carried out at 70°C to 78°C for 1.0 to 2 h; after all the shell pre-emulsion is added and the reaction is completed, the temperature is raised to 80 to 85°C and kept warm for 1 to 3 h to obtain the polymer emulsion.

[0031] The present invention also provides the application of the foaming regulator aid described above or the foaming regulator aid prepared by the preparation method described above in the processing of PVC and / or CPE foaming materials.

[0032] The technical solution provided by the present invention has at least the following beneficial effects:

[0033] The foaming regulator aid provided by the present invention has a core-shell structure. When preparing the shell layer, organic barium is introduced, which is beneficial to improving the thermal stability and providing good auxiliary lubricity; at the same time, a relatively high amount of the first cross-linking agent and molecular weight regulator (isooctyl mercaptoacetate and / or C10 - C18 alkyl mercaptan) are introduced. The coating of short side chains in the shell layer is beneficial to the dispersion of the foaming regulator. At the same time, the steric hindrance effect and the end groups of the molecular weight regulator at the ends of the relatively high content of side chains can solve the problem of the chemical extrusion foam cell shrinkage during the cooling and shaping of traditional high-intrinsic viscosity foaming regulators, play a certain role in stabilizing the foam, and can produce foaming materials with more uniform cell structure and lower density. At the same time, the emulsion polymerization process is beneficial to safe production. Detailed Embodiments

[0034] To facilitate the understanding of 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 of the present invention, and do not mean that the present invention is limited only to the following embodiments.

[0035] 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. In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0036] On the one hand, the present invention provides a foaming regulator aid, which is obtained by emulsion polymerization of a shell pre-emulsion and a core emulsion in the presence of a first initiator, and then dehydrated and dried;

[0037] The shell pre-emulsion is obtained by pre-emulsifying shell raw materials, and the shell raw materials include alkyl methacrylate monomers, an organic barium solution, a first crosslinking agent, a molecular weight regulator, a first emulsifier, and water with a mass ratio of (60-75):(10-25):(1.5-2.7):(3.0-5.4):(0.9-1.8):(15-24).

[0038] The core layer emulsion is obtained by reacting a pre-emulsion of core layer raw materials in the presence of a second initiator. The core layer raw materials include alkyl acrylate monomers, alkyl methacrylate monomers, a second crosslinking agent, a second emulsifier, and water with a mass ratio of (20-30):(5-10):(0.2-0.5):(0.3-0.6):(250-300).

[0039] The molecular weight regulator in the shell raw materials is selected from at least one of isooctyl thioglycolate and C10-C18 alkyl mercaptans, and more preferably isooctyl thioglycolate.

[0040] During the processing of foaming materials such as PVC and CPE using traditional high molecular weight foaming regulators, such as high molecular weight acrylate copolymers (ACR), adding the foaming regulator additive of the present invention can improve thermal stability, provide good auxiliary lubricity, etc., make the surface of the extrudate smooth and flat, and can also play a role in stabilizing bubbles, obtaining a foaming material with more uniform cell structure and lower density.

[0041] The foaming regulator aid of the present invention has a core-shell structure. Organic barium is introduced into the shell layer, and the organic barium monomer is surface-grafted on the high molecular weight acrylate, which helps to improve the thermal stability and has good auxiliary lubricity at the same time. For example, an extrudate with a smooth and flat surface can be obtained. At the same time, a first crosslinking agent and a relatively large amount of isooctyl mercaptoacetate and / or C10-C18 alkyl mercaptan as a molecular weight regulator are added during the preparation of the shell layer; the multi-functional monomer as the first crosslinking agent has more than two double bonds that can react during free radical polymerization, so that the formed polymer chains will undergo crosslinking reactions; however, in the present invention, by adding a relatively high amount of isooctyl mercaptoacetate and / or C10-C18 alkyl mercaptan as a molecular weight regulator, the molecular chains of the polymer shell layer are finally shortened, the molecular weight is reduced, and due to the presence of the multi-functional monomer as the first crosslinking agent, many short branched chains will be generated; on the one hand, the molecular weight is controlled and it is easy to disperse; on the other hand, some molecular chain ends carry groups of the molecular weight regulator (isooctyl mercaptoacetate and / or C10-C18 alkyl mercaptan), making the formation and retention of bubbles during extrusion foaming easier. The foaming regulator aid of the present invention, by introducing organic barium and forming a short-branched coating on the shell layer, with a relatively high content of molecular weight regulator (isooctyl mercaptoacetate and / or C10-C18 alkyl mercaptan) end groups at the ends of the branched chains, can not only improve the thermal stability and provide good auxiliary lubricity, but also solve the problem of chemical extrusion cell shrinkage during cooling and shaping when a high-intrinsic viscosity foaming regulator is added alone during extrusion, play a role in stabilizing bubbles, and can prepare a foamed material with more uniform cells and lower density.

[0042] Preferably, the alkyl groups in the alkyl methacrylate monomers in the shell layer raw material and the core layer raw material are respectively independently straight-chain alkyl groups of C1-C6 or branched-chain alkyl groups of C1-C8. Specific examples of the alkyl methacrylate monomers include n-butyl methacrylate, methyl methacrylate, ethyl methacrylate, etc.;

[0043] Preferably, the alkyl group in the alkyl acrylate monomer is a straight-chain alkyl group of C1-C6 or a branched-chain alkyl group of C1-C8. Examples of the alkyl acrylate monomer include n-butyl acrylate, isooctyl acrylate, etc.;

[0044] Preferably, the first crosslinking agent and the second crosslinking agent are respectively independently selected from at least one of allyl methacrylate, allyl acrylate, divinylbenzene, trimethylolpropane triacrylate, 3(propoxy)propyltriacrylate;

[0045] Preferably, the first emulsifier and the second emulsifier are respectively independently selected from anionic emulsifiers; the anionic emulsifier is preferably selected from at least one of potassium fatty acid soaps, alkyl sulfates, alkyl benzene sulfonates; more preferably, the emulsifier is sodium dodecyl sulfate.

[0046] Preferably, the first initiator and the second initiator are each independently selected from at least one of potassium persulfate and ammonium persulfate, and more preferably potassium persulfate;

[0047] In a preferred embodiment, the alkyl acrylate monomer is n-butyl acrylate; the use of the preferred monomer is conducive to further improving the improvement effect of the foaming regulator additive on the thermal stability during the processing of the foaming material, and taking into account a lower density.

[0048] Preferably, the organic barium solution is one or both of a barium acrylate solution and a barium methacrylate solution. Further preferably, the preparation steps of the organic barium solution include: refluxing and condensing a raw material including barium carbonate, raw material A and water with a mass ratio of 1:(1-1.2):(10-20) at 70-90 °C for 1-2 h, and the raw material A is selected from acrylic acid and / or methacrylic acid. By this method of preparing the organic barium solution, barium ions can be introduced into the acrylate polymer; the present invention preferably uses an organic barium derived from acrylic acid and / or methacrylic acid. On the one hand, this type of preferred organic barium can directly participate in free radical polymerization to form a copolymer with the foaming regulator additive of the present invention. On the other hand, the organic barium raw material based on acrylic acid and / or methacrylic acid is easy to obtain and the preparation method is simple. In addition, this type of organic barium can form a more uniform polymer with the alkyl methacrylate monomer and the alkyl acrylate monomer; thus, a foaming regulator additive with better performance can be obtained.

[0049] Preferably, the mass ratio of the core layer emulsion to the total mass of all the shell layer raw materials is (275-342):(90.4-134.1).

[0050] In a more preferred embodiment, the shell layer raw materials include an alkyl methacrylate monomer, an organic barium solution, a first crosslinking agent, a molecular weight regulator, a first emulsifier and water with a mass ratio of (70-75):(12-20):(2.0-2.4):(3.0-5.4):(0.9-1.8):(15-24); the core layer raw materials include an alkyl acrylate monomer, an alkyl methacrylate monomer, a second crosslinking agent, a second emulsifier and water with a mass ratio of (24-27):(5-10):(0.2-0.5):(0.3-0.6):(250-300); and the alkyl acrylate monomer is n-butyl acrylate, and the molecular weight regulator is isooctyl mercaptoacetate. The foaming regulator additive of the present invention prepared by this preferred method is conducive to obtaining a foaming regulator additive with more excellent performance, and helps to obtain a foaming material that can simultaneously take into account more excellent thermal stability and a relatively low density.

[0051] On the other hand, the present invention provides a method for preparing the foaming regulator assistant described above, comprising the following steps:

[0052] S1. Prepare the core layer emulsion: Put the core layer raw materials into a reaction kettle, pre-emulsify at a temperature of 15°C to 35°C under a protective gas atmosphere to obtain a pre-emulsion, then raise the temperature to 70°C to 78°C, add a second initiator, and react at 70°C to 78°C for 3 to 5 hours under a protective gas atmosphere, and then raise the temperature to 80°C to 85°C and keep warm for 1 to 2 hours to obtain the core layer emulsion;

[0053] S2. Pre-emulsify the shell layer raw materials at a temperature of 15°C to 35°C under a protective gas atmosphere to obtain the shell layer pre-emulsion, and then feed it into the core layer emulsion by dropping or adding in multiple steps, and carry out emulsion polymerization in the presence of the first initiator to obtain a polymer emulsion;

[0054] S3. Dehydrate and dry the polymer emulsion to obtain the foaming regulator assistant. For example, carry out the dehydration and drying by spray drying, which produces less wastewater and is beneficial to energy conservation and emission reduction.

[0055] In the text, the protective gas described above is, for example, nitrogen, etc.

[0056] In some specific embodiments, in step S1, the pre-emulsification time is 0.5 to 1.5 hours;

[0057] In some specific embodiments, in step S2, the pre-emulsification time is 0.5 to 1.5 hours;

[0058] In some specific embodiments, in step S1, the dosage of the second initiator is 0.08% to 0.15% of the total mass of the alkyl acrylate monomers and the alkyl methacrylate monomers in the core layer raw materials.

[0059] In some embodiments, in step S2, the shell layer pre-emulsion is fed by dropping; specifically, the shell layer pre-emulsion is dropped into the core layer emulsion at a temperature of 70°C to 78°C and reacts in the presence of the first initiator; the dropping time of the shell layer pre-emulsion is 2 to 5 hours, and after dropping, the temperature is raised to 80°C to 85°C and kept warm for 1 to 3 hours to obtain the polymer emulsion; the dosage of the first initiator is 0.08% to 0.15% of the mass of the alkyl methacrylate monomers contained in the shell layer pre-emulsion;

[0060] In some other embodiments, in step S2, the shell pre-emulsion is fed in a multi-step addition manner; specifically, the shell pre-emulsion is divided into 2-5 steps and added into the core emulsion at a temperature of 70°C to 78°C. When adding the shell pre-emulsion in each step, the first initiator with a mass of 0.08% to 0.15% of the mass of the alkyl methacrylate monomer contained in the shell pre-emulsion added in this step is correspondingly added. After adding the shell pre-emulsion in each step, the reaction is carried out at 70°C to 78°C for 1.0 to 2 h; after all the shell pre-emulsion is added and the reaction is completed, the temperature is raised to 80°C to 85°C and kept warm for 1 to 3 h to obtain the polymer emulsion. Preferably, the shell pre-emulsion is evenly divided into 2-5 portions and correspondingly added step by step in 2-5 steps, with one portion added in each step; more preferably, the shell pre-emulsion is evenly divided into 3 portions and correspondingly added step by step in 3 steps.

[0061] The present invention also provides the application of the foaming regulator auxiliary agent described above or the foaming regulator auxiliary agent prepared by the preparation method described above in the processing of PVC and / or CPE foaming materials. The foaming regulator auxiliary agent of the present invention grafts an organic barium monomer on the surface of a high-molecular-weight acrylate, and at the same time, a cross-linking agent and a relatively high amount of isooctyl mercaptoacetate and / or C10-C18 alkyl mercaptan are added as molecular weight regulators during preparation. There is a short-branched chain coating on the shell layer, and at the same time, there are steric hindrance effects and a relatively high content of molecular weight regulator end groups at the ends of the branches. On the one hand, it can improve the thermal stability and provide good auxiliary lubricity, making the extrudate smooth and flat; on the other hand, it is beneficial to the dispersion of the foaming regulator and solves the problem of chemical extrusion cell shrinkage during cooling and shaping of traditional high-intrinsic viscosity foaming regulators, playing a certain role in stabilizing the foam and enabling the production of foaming materials with more uniform cells and lower density. The foaming regulator auxiliary agent provided by the present invention is particularly suitable for the processing and production of foaming materials of PVC and CPE, and can expand the application range of acrylate foaming regulators.

[0062] 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.

[0063] 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.

[0064] The screw extruder used in the method according to the present invention can be a conventional screw extruder, such as including but not limited to a conical screw extruder, a parallel screw extruder, etc.

[0065] <The sources of some raw materials used in the following examples or comparative examples>

[0066] Methyl methacrylate, Shandong Hongxu Chemical Co., Ltd.;

[0067] n-Butyl methacrylate, Huayi Hefeng Special Chemicals Zibo Co., Ltd.;

[0068] Isooctyl acrylate, Zhejiang Satellite Petrochemical Co., Ltd.;

[0069] n-Butyl acrylate, Jiangsu Sandie Chemical Co., Ltd.;

[0070] Sodium dodecyl sulfate, Kao Corporation of Japan;

[0071] Sodium dodecylbenzenesulfonate, Kao Corporation of Japan;

[0072] Potassium persulfate, Hebei Jiheng Group Co., Ltd.;

[0073] Ammonium persulfate, Hebei Jiheng Group Co., Ltd.;

[0074] Allyl methacrylate, Zibo Qisu Environmental Protection Technology Co., Ltd.;

[0075] Methacrylic acid, Qixiang Huali New Materials Co., Ltd.;

[0076] Acrylic acid, Jiangsu Sandie Chemical Co., Ltd.;

[0077] Trimethylolpropane triacrylate, Shandong Dongde New Materials Co., Ltd.;

[0078] Isooctyl mercaptoacetate, Qingdao Jiahua Chemical Co., Ltd.

[0079] PVC (K57), Qilu Petrochemical;

[0080] Heavy calcium carbonate, Qingzhou Yuxin Calcium Industry Co., Ltd.;

[0081] Calcium / zinc stabilizer RH-915, Shandong Ruihe New Materials Co., Ltd.;

[0082] Oxidized polyethylene wax Luwax OA2, BASF Group;

[0083] Pentaerythritol stearate DN-PETS, Shandong Dawn Group Co., Ltd.;

[0084] Polyethylene wax DN-1, Shandong Dawn Group Co., Ltd.;

[0085] AC blowing agent SG-806, Shandong Shitong High Polymer Materials Co., Ltd.;

[0086] NC blowing agent SG-985, Shandong Shitong High Polymer Materials Co., Ltd.;

[0087] Blowing regulator HL-100, Shandong Rike Chemical Co., Ltd.

[0088] In the examples or comparative examples, the barium methacrylate stock solution used was prepared according to the following steps: Barium carbonate, methacrylic acid and water with a mass ratio of 1:1.2:13 were refluxed and condensed at 78 °C for 2 h; the barium methacrylate stock solution was obtained.

[0089] In the examples or comparative examples, the barium acrylate stock solution used was prepared according to the following steps: Barium carbonate, acrylic acid and water with a mass ratio of 1:1:13.2 were refluxed and condensed at 78 °C for 2 h; the barium acrylate stock solution was obtained.

[0090] <Test method>

[0091] Vicat softening point: Determination of Vicat softening temperature (VST) of thermoplastics - GB / T 1633 2000;

[0092] Density of foamed board: Detected using a drainage method density balance.

[0093] Example 1

[0094] S1. Preparation of core layer emulsion: n-Butyl acrylate, n-butyl methacrylate, allyl methacrylate, sodium dodecyl sulfate and water were added into the reaction kettle, where the mass ratio of n-butyl acrylate: n-butyl methacrylate: allyl methacrylate: sodium dodecyl sulfate: water was 25:5:0.2:0.4:270. Under a nitrogen atmosphere, the temperature was controlled at 15 °C - 35 °C for pre-emulsification for 0.5 h. After pre-emulsification was completed, the pre-emulsion was heated to 75 °C, and potassium persulfate as an initiator accounting for 0.1% of the total mass of the acrylic acid alkyl ester monomers and methacrylic acid alkyl ester monomers was added. The reaction was carried out at 75 °C - 78 °C for 3 h, and then the temperature was raised to 80 °C and kept warm for 1.5 h to obtain the core layer emulsion.

[0095] S2. Preparation of shell layer: The feeding ratio was based on the mass ratio of the core layer emulsion to the total mass of all shell layer raw materials being 300.63:114.025. The shell layer raw materials included methyl methacrylate, barium methacrylate stock solution, allyl methacrylate, isooctyl mercaptoacetate, sodium dodecyl sulfate and water with a mass ratio of 75:13:2.25:4.5:1.2:18. The above shell layer raw materials were pre-emulsified at 15 °C - 35 °C for 0.5 h under a nitrogen atmosphere. After pre-emulsification was completed, the shell layer pre-emulsion was obtained; the temperature of the core layer emulsion was adjusted to 75 °C, and the shell layer pre-emulsion was evenly added to the core layer emulsion in 3 steps. When adding the shell layer pre-emulsion in each step, potassium persulfate as an initiator with a mass of 0.1% of the mass of the methacrylic acid alkyl ester monomers contained in the shell layer pre-emulsion added in that step was added accordingly. After adding the shell layer pre-emulsion in each step, the reaction was carried out at 75 - 78 °C for 1.5 h. After all the shell layer pre-emulsion was added and the reaction was completed, the temperature was raised to 80 °C and kept warm for 2 h to obtain the foaming regulator additive emulsion.

[0096] S3. Spray drying: The foaming regulator auxiliary agent emulsion is obtained by spray drying to get the foaming regulator auxiliary agent of Example 1.

[0097] Example 2

[0098] S1. Preparation of core layer emulsion: Isooctyl acrylate, n-butyl methacrylate, trimethylolpropane triacrylate, sodium dodecylbenzenesulfonate and water are added into the reaction kettle, where the mass ratio of isooctyl acrylate: n-butyl methacrylate: trimethylolpropane triacrylate: sodium dodecylbenzenesulfonate: water is 24:6:0.4:0.6:260. Under the nitrogen atmosphere, the temperature is controlled at 15°C - 35°C for pre-emulsification for 0.5 h. After the pre-emulsification is completed, the pre-emulsion is heated to 70°C, and ammonium persulfate as the initiator accounting for 0.08% of the total mass of the acrylic alkyl ester monomers and the methacrylic alkyl ester monomers is added, and the reaction is carried out at 70°C - 75°C for 3 h, and then heated to 80°C for heat preservation for 1.5 h to obtain the core layer emulsion.

[0099] S2. Preparation of shell layer: The feeding ratio is based on the mass ratio of the core layer emulsion to the total mass of all shell layer raw materials being 291.02:120.76. The shell layer raw materials include methyl methacrylate, barium methacrylate feed liquid, trimethylolpropane triacrylate, isooctyl mercaptoacetate, sodium dodecyl sulfate and water with a mass ratio of 75:13:2.4:4.8:1.5:24. The above shell layer raw materials are pre-emulsified at 15°C - 35°C for 0.5 h under the nitrogen atmosphere. After the pre-emulsification is completed, the shell layer pre-emulsion is obtained; the temperature of the core layer emulsion is adjusted to 75°C, and the shell layer pre-emulsion is evenly added to the core layer emulsion in 3 steps. When adding the shell layer pre-emulsion in each step, ammonium persulfate as the initiator with a mass of 0.08% of the mass of the methacrylic alkyl ester monomers contained in the shell layer pre-emulsion added in this step is added accordingly. After adding the shell layer pre-emulsion in each step, the reaction is carried out at 75 - 78°C for 1.5 h. After all the shell layer pre-emulsion is added and the reaction is completed, it is heated to 80°C for heat preservation for 1.5 h to obtain the foaming regulator auxiliary agent emulsion.

[0100] S3. Spray drying: The foaming regulator auxiliary agent emulsion is obtained by spray drying to get the foaming regulator auxiliary agent of Example 2.

[0101] Example 3

[0102] S1. Preparation of core layer emulsion: n-butyl acrylate, ethyl methacrylate, allyl acrylate, sodium dodecylbenzenesulfonate and water were added into a reaction kettle. The mass ratio of n-butyl acrylate: ethyl methacrylate: allyl acrylate: sodium dodecylbenzenesulfonate: water was 27:6:0.3:0.4:280. Under a nitrogen atmosphere, the temperature was controlled at 15°C - 35°C for pre-emulsification for 0.5 h. After pre-emulsification was completed, the pre-emulsion was heated to 70°C, and potassium persulfate as an initiator accounting for 0.12% of the total mass of alkyl acrylate monomers and alkyl methacrylate monomers was added. The reaction was carried out at 70°C - 75°C for 3 h, and then heated to 80°C for heat preservation for 1.5 h to obtain the core layer emulsion.

[0103] S2. Preparation of shell layer: The feeding ratio was based on the mass ratio of the core layer emulsion to the total mass of all shell layer raw materials being 313.7:118.58. The shell layer raw materials included methyl methacrylate, barium acrylate solution, allyl acrylate, isooctyl mercaptoacetate, sodium dodecyl sulfate and water with a mass ratio of 66:21:1.5:4.5:1.5:24. The above shell layer raw materials were pre-emulsified at 15°C - 35°C for 0.5 h under a nitrogen atmosphere. After pre-emulsification was completed, a shell layer pre-emulsion was obtained; the temperature of the core layer emulsion was adjusted to 75°C, and the shell layer pre-emulsion was added to the core layer emulsion in 3 equal steps. When adding the shell layer pre-emulsion in each step, potassium persulfate as an initiator accounting for 0.12% of the mass of alkyl methacrylate monomers contained in the shell layer pre-emulsion added in that step was added accordingly. After adding the shell layer pre-emulsion in each step, the reaction was carried out at 75 - 78°C for 1.5 h. After all the shell layer pre-emulsion was added and the reaction was completed, the temperature was raised to 80°C for heat preservation for 1.5 h to obtain a foaming regulator auxiliary emulsion.

[0104] S3. Spray drying: The foaming regulator auxiliary emulsion was obtained by spray drying to get the foaming regulator auxiliary of Example 3.

[0105] Example 4

[0106] It was carried out with reference to Example 1, the difference being that:

[0107] In step S1, the mass ratio of n-butyl acrylate: n-butyl methacrylate: allyl methacrylate: sodium dodecyl sulfate: water was 30:5:0.4:0.5:270.

[0108] Example 5

[0109] It was carried out with reference to Example 1, the difference being that: In step S1, n-butyl acrylate in Example 1 was replaced with isooctyl acrylate.

[0110] Example 6

[0111] It is carried out with reference to Example 1, except that: in step S2, isooctyl thioglycolate in Example 1 is replaced with dodecyl mercaptan.

[0112] Example 7

[0113] It is carried out with reference to Example 1, except that:

[0114] In step S1, the mass ratio of n-butyl acrylate: n-butyl methacrylate: allyl methacrylate: sodium dodecyl sulfate: water is 20:5:0.2:0.4:270.

[0115] Example 8

[0116] It is carried out with reference to Example 1, except that:

[0117] In step S1, the mass ratio of n-butyl acrylate: n-butyl methacrylate: allyl methacrylate: sodium dodecyl sulfate: water is 25:5:0.5:0.4:270.

[0118] In step S2, the shell raw materials include methyl methacrylate, barium methacrylate feed liquid, allyl methacrylate, isooctyl thioglycolate, sodium dodecyl sulfate and water with a mass ratio of 75:13:2.7:4.5:1.2:18.

[0119] Example 9

[0120] It is carried out with reference to Example 1, except that in step S2, the shell pre-emulsion is fed in by dropping; the same parts as in Example 1 will not be elaborated, and only the different operations in step S2 will be described below:

[0121] In step S2, after the pre-emulsification is completed to obtain the shell pre-emulsion; adjust the temperature of the core emulsion to 75 °C, and add the shell pre-emulsion into the core emulsion by dropping, and correspondingly add potassium persulfate as the initiator with a mass of 0.1% of the mass of the alkyl methacrylate monomers contained in the shell pre-emulsion added in this step. The dropping time of the shell pre-emulsion is 3 hours. After all the shell pre-emulsion is added and the reaction is completed, raise the temperature to 80 °C and keep it warm for 2 h to obtain the foaming regulator additive emulsion.

[0122] Comparative Example 1

[0123] It is carried out with reference to Example 1, except that: barium methacrylate feed liquid is not added in step S2.

[0124] Comparative Example 2

[0125] It is carried out with reference to Example 1, except that: the cross-linking agent allyl methacrylate and isooctyl thioglycolate are not added to the shell raw materials in step S2.

[0126] Comparative Example 3

[0127] It was carried out with reference to Example 1, except that: in the shell material in step S2, the mass ratio of methyl methacrylate, barium methacrylate solution, allyl methacrylate, isooctyl mercaptoacetate, sodium dodecyl sulfate and water was 75:13:1.2:2.4:1.2:18.

[0128] Application performance detection:

[0129] The foaming regulator aids prepared in the above-mentioned respective examples and comparative examples were used for the processing of PVC foamed materials. The preparation method of the PVC foamed materials was as follows: the raw materials were mixed in a high-speed mixer to 110 °C, and then cooled to 44 °C and discharged; the mixed raw materials were all passed through a 40-mesh sieve, and then melt-plasticized, extruded and cooled by a twin-screw extruder.

[0130] Among them, the extrusion process conditions were as follows:

[0131] Barrel temperature: 178 - 185 °C;

[0132] Motor speed: 40 rpm;

[0133] Feeding speed: 1000 rpm;

[0134] Traction speed: 500 rpm.

[0135] The raw material formula of the PVC foamed material is shown in Table 1.

[0136] Table 1

[0137]

[0138]

[0139] Among them, the foaming regulator aids in Table 1 were the foaming regulator aids prepared in the above-mentioned respective examples and comparative examples, that is, the foaming regulator aids prepared in the above-mentioned respective examples and comparative examples were respectively processed into PVC foamed materials according to the formula in Table 1 to obtain foamed plates, and relevant performance detections were carried out. The specific detection results are shown in Table 2 below.

[0140] Table 2

[0141] <![CDATA[Average foaming density, g / cm 3 > Vicat softening point, °C Example 1 0.439 90.9 Example 2 0.450 90.1 Example 3 0.462 87.8 Example 4 0.441 89.9 Example 5 0.450 89.9 Example 6 0.465 90.2 Example 7 0.454 90.9 Example 8 0.472 90.5 Example 9 0.443 90.9 Comparative Example 1 0.470 84.9 Comparative Example 2 0.510 85.9 Comparative Example 3 0.493 85.6

[0142] The test data of the foamed sheets prepared with the foaming regulator aids of the above Examples 1-9 and Comparative Examples 1-3 are shown in Table 1, and the results are analyzed as follows: In the field of foaming, uneven dispersion of bubbles and too small bubble spacing in the foamed sheets will cause uneven mechanical properties everywhere in the sheets. In addition, if the foaming density is high, fewer sheets can be made with the same amount of plastic material, resulting in high costs; if the foaming density is low, more sheets can be prepared with the same amount of plastic material under the condition of meeting the mechanical property requirements, which is beneficial to cost reduction. It can be seen from the experimental results that the foamed sheets prepared with the foaming regulator aids obtained in the embodiments of the present invention have a lower density and significantly better thermal stability. Among them, compared with other embodiments, Examples 1 and 9 use the preferred shell layer raw material ratio, the preferred core layer raw material ratio, the preferred acrylic alkyl ester monomer and the molecular weight regulator, and can obtain a foaming regulator aid with more excellent performance. When applied in the preparation of foamed sheets, it can achieve better balance between excellent thermal stability and lower density.

[0143] It is easy to understand that the above embodiments are merely examples given 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 on the basis of 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 foaming regulator auxiliary agent, characterized in that: The foaming regulator auxiliary agent is obtained by emulsion polymerization of the shell layer pre-emulsion and the core layer emulsion in the presence of a first initiator, followed by dehydration and drying; The shell pre-emulsion is obtained by pre-emulsifying shell raw materials, wherein the shell raw materials include methacrylic acid alkyl ester monomers, organic barium liquid, a first cross-linking agent, a molecular weight regulator, a first emulsifier and water in a mass ratio of (60-75): (10-25): (1.5-2.7): (3.0-5.4): (0.9-1.8): (15-24); The core layer emulsion is obtained by reacting a pre-emulsified liquid of a core layer raw material in the presence of a second initiator, wherein the core layer raw material comprises an alkyl acrylate monomer, an alkyl methacrylate monomer, a second crosslinking agent, a second emulsifier and water in a mass ratio of (20-30): (5-10): (0.2-0.5): (0.3-0.6): (250-300); The molecular weight regulator in the shell layer raw material is selected from at least one of isooctyl thioglycolate and C10-C18 alkyl mercaptan.

2. The foaming regulator auxiliary according to claim 1, characterized in that The alkyl groups in the alkyl methacrylate monomers in the shell layer raw material and the core layer raw material are independently C1-C6 straight-chain alkyl groups or C1-C8 branched-chain alkyl groups; And / or, the alkyl group in the acrylic acid alkyl ester monomer is a C1-C6 straight-chain alkyl group or a C1-C8 branched-chain alkyl group; and / or, the first cross-linking agent and the second cross-linking agent are independently selected from at least one of allyl methacrylate, allyl acrylate, divinylbenzene, trimethylolpropane triacrylate, and 3 (propoxy) glycerol triacrylate; and / or, the first emulsifier and the second emulsifier are independently selected from anionic emulsifiers; And / or, the first initiator and the second initiator are independently selected from at least one of potassium persulfate and ammonium persulfate; And / or, the organic barium solution is one or both of an acrylic acid barium solution and a methacrylic acid barium solution.

3. The foaming regulator auxiliary agent according to claim 2, characterized in that The anionic emulsifier is selected from at least one of fatty acid potassium soap, alkyl sulfate, and alkyl benzene sulfonate.

4. The foaming regulator auxiliary according to any one of claims 1 to 3, characterized in that The preparation step of the organic barium liquid comprises: subjecting raw materials including barium carbonate, raw material A and water in a mass ratio of 1:(1-1.2):(10-20) to reflux condensation reaction at 70-90° C. for 1-2 hours; the raw material A is selected from acrylic acid and / or methacrylic acid.

5. The foaming regulator auxiliary agent according to any one of claims 1 to 3, characterized in that: The ratio of the mass of the core layer emulsion to the total mass of the shell layer raw material is (275-342): (90.4-134.1).

6. The foaming regulator auxiliary according to any one of claims 1 to 3, characterized in that The shell layer raw materials include methacrylate alkyl ester monomers, organic barium liquid, a first cross-linking agent, a molecular weight regulator, a first emulsifier and water in a mass ratio of (70-75): (12-20): (2.0-2.4): (3.0-5.4): (0.9-1.8): (15-24); The core layer raw materials include alkyl acrylate monomers, alkyl methacrylate monomers, a second crosslinking agent, a second emulsifier and water in a mass ratio of (24-27): (5-10): (0.2-0.5): (0.3-0.6): (250-300); The alkyl acrylate monomer is n-butyl acrylate; The molecular weight regulator is isooctyl thioglycolate.

7. The method for preparing the foaming regulator auxiliary agent according to any one of claims 1 to 6, characterized in that: The steps include: S1, preparing a core layer emulsion: putting the core layer raw material into a reactor, pre-emulsifying at 15°C to 35°C under a protective gas atmosphere to obtain a pre-emulsified liquid, then heating to 70°C to 78°C, adding the second initiator, reacting at 70°C to 78°C under a protective gas atmosphere for 3 to 5 hours, then heating to 80°C to 85°C and keeping the temperature for 1 to 2 hours to obtain a core layer emulsion; S2, pre-emulsifying the shell layer raw material at a temperature of 15° C. to 35° C. under a protective gas atmosphere to obtain the shell layer pre-emulsion, then adding the shell layer pre-emulsion to the core layer emulsion by dropwise addition or multi-step addition, and performing emulsion polymerization in the presence of the first initiator to obtain a polymer emulsion; S3, dehydrating and drying the polymer emulsion to obtain the foaming regulator auxiliary agent.

8. The preparation method according to claim 7, characterized in that: In step S1, the pre-emulsification time is 0.5 to 1.5 hours; And / or, in step S2, the pre-emulsification time is 0.5 to 1.5 hours; And / or, in step S1, the amount of the second initiator used is 0.08% to 0.15% of the total mass of the alkyl acrylate monomer and the alkyl methacrylate monomer in the core layer raw material.

9. The preparation method according to claim 7, characterized in that: In step S2, the shell pre-emulsion is added dropwise into the core emulsion at a temperature of 70° C. to 78° C., and reacted in the presence of the first initiator; the shell pre-emulsion is added dropwise for 2 to 5 hours, and after the addition is completed, the temperature is raised to 80 to 85° C. and kept for 1 to 3 hours to obtain the polymer emulsion; the amount of the first initiator is 0.08% to 0.15% of the mass of the alkyl methacrylate monomer contained in the shell pre-emulsion; Alternatively, in step S2, the shell pre-emulsion is added into the core emulsion at a temperature of 70°C to 78°C in 2-5 steps, and when the shell pre-emulsion is added in each step, the first initiator is added in an amount of 0.08% to 0.15% of the mass of the alkyl methacrylate monomer contained in the shell pre-emulsion added in that step, and after each step of adding the shell pre-emulsion, the reaction is carried out at 70°C to 78°C for 1.0 to 2h; after all the shell pre-emulsions are added and the reaction is completed, the temperature is raised to 80 to 85°C and kept warm for 1 to 3h to obtain the polymer emulsion.

10. Use of the foaming regulator auxiliary agent according to any one of claims 1 to 6 or the foaming regulator auxiliary agent prepared by the preparation method according to any one of claims 7 to 9 in the processing of PVC and / or CPE foaming materials.

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