A fluorinated acrylate-coated anti-dripping agent, and its preparation method and application

Abstract

The present invention relates to the technical field of flame-retardant thermoplastic resins, and provides a fluorinated acrylate-coated anti-drip agent, its preparation method, and application. The anti-drip agent has a core-shell structure, wherein a high-molecular-weight fluoroethylene polymer serves as the core layer of the core-shell structure, and a polymer formed by polymerization of an acrylate monomer and a fluorinated acrylate monomer serves as the shell layer of the core-shell structure. While ensuring good dispersibility, the anti-drip agent can maintain the stability of the core-shell structure, effectively improve the compatibility of the anti-drip agent with the substrate, significantly improve the dripping phenomenon of thermoplastic polymer materials, and make the anti-drip effect more stable. The anti-drip agent can be widely used in the preparation of flame-retardant materials.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoplastic resin products, and in particular to an anti-dripping agent of fluorine-containing acrylate coated polytetrafluoroethylene, a preparation method thereof and applications thereof, especially applications in thermoplastic resin products. Background Art

[0002] Thermoplastic materials are widely used and are characterized by being lightweight, easy to manufacture, easy to dye, recyclable, and convenient for large-scale production. They are used in various fields of life and production. However, thermoplastic materials are flammable and easily soften, deform, or even sag when heated, which can easily cause fires and secondary disasters. Therefore, when manufacturing thermoplastic materials, people can obtain flame retardant properties by adding one or more flame retardants, including minerals (ATH and magnesium hydroxide), organohalogen compounds (organochlorine and organobromine), and organophosphorus compounds (organophosphates, phosphonates, and phosphinates). Although these materials can effectively enhance the flame retardancy of the resin, they will still melt and drip during the combustion process, which can easily cause secondary disasters.

[0003] Polytetrafluoroethylene (PTFE) is a widely used anti-drip agent. However, due to its dense surface carbon-carbon bonds, its surface energy is low and its dispersibility with other materials is poor. Therefore, surface modification of PTFE is necessary to improve its wettability and compatibility. The main surface modification methods include chemical modification with sodium naphthalene solution, plasma surface modification, high-energy irradiation surface modification, and coating modification. Currently, the following technologies are available for PTFE-coated anti-drip agents:

[0004] Patent No. 202010233099.5 relates to a method for preparing a silicone-coated polytetrafluoroethylene (PTFE) anti-drip agent. This method uses a mixed solution of palladium chloride and stannous chloride to treat dry PTFE material under ultrasonic conditions, generating reactive groups on its surface. UV light polymerization is then performed simultaneously to graft amide bonds onto the surface. The silicone is then coated onto the surface of the PTFE particles through a hydrolysis and polycondensation reaction of the silicone. The anti-drip agent produced by this method exhibits improved affinity and performance with the resin, resulting in a more complete coating without compromising the material's compatibility with the resin, ensuring the material's mechanical properties and gloss.

[0005] Patent No. 201811056085.X relates to an anti-drip agent with a toughening effect and its synthesis method. The synthesis method comprises: synthesizing an organopolysiloxane core emulsion; and synthesizing an anti-drip agent with a toughening effect. This invention's synthesis method involves polymerizing organosilicon and polytetrafluoroethylene, followed by sequential coating with a soft monomer and a hard monomer. The resulting anti-drip agent exhibits excellent anti-drip properties and improves the material's impact strength. The process is simple and low-cost.

[0006] 201811001561.8 relates to an anti-dripping agent with excellent compatibility and a synthesis method thereof. The synthesis method includes: synthesis of an anti-dripping agent with excellent compatibility; the specific method is to stir tetrafluoroethylene emulsion, dispersant and distilled water at a high-speed shearing temperature of 1000-2000rpm, adjust the pH value of the reaction system, add initiator, hydroxyethyl methacrylate and other acrylate monomers, react at a certain temperature for a period of time, wash, centrifuge and dry the reaction product to obtain an anti-dripping agent with excellent compatibility. The obtained anti-dripping agent has excellent compatibility, simple process and low cost.

[0007] Although the above patents solve the dispersibility problem of polytetrafluoroethylene coated anti-drip agents, during use, the polytetrafluoroethylene may be locally aggregated due to the uneven coating, ultimately leading to unstable flame retardant anti-drip properties.

[0008] Therefore, researching a more practical anti-dripping agent becomes one of the problems to be solved urgently by those skilled in the art. Summary of the Invention

[0009] To overcome the shortcomings and deficiencies of the prior art, the present invention provides a fluorinated acrylate-coated anti-drip agent, its preparation method, and application. The anti-drip agent has a core-shell structure, wherein a high-molecular-weight fluoroethylene polymer serves as the core layer of the core-shell structure, and a polymer formed by polymerization of an acrylate monomer and a fluorinated acrylate monomer serves as the shell layer. While ensuring good dispersibility, the anti-drip agent maintains the stability of the core-shell structure, effectively improving the compatibility of the anti-drip agent with the substrate, significantly improving the dripping phenomenon of thermoplastic polymer materials, and providing a more stable anti-drip effect. The anti-drip agent can be widely used in the preparation of flame-retardant materials.

[0010] The purpose of the present invention is to provide an anti-drip agent and its preparation and application method, which can improve the anti-drip performance of flammable thermoplastic resins during combustion and can be industrialized. The inventor's main inventive concept is as follows: Taking polytetrafluoroethylene as a high molecular weight fluoroethylene polymer as an example,

[0011] The basic principle of PTFE core-shell coating is to add a stable PTFE dispersion as a seed emulsion to the system, followed by the addition of a fluorinated acrylate shell monomer. Due to interfacial tension, the shell monomer aggregates to the surface of the PTFE seed. Polymerization is then initiated by the addition of a free radical initiator, which polymerizes to form a polymer shell on the surface of the PTFE seed, completing the coating. Depending on the ratio of the core-shell monomers, the shell thickness can be adjusted to 20-80nm. The coated PTFE particles have good dispersibility. After being uniformly mixed with a thermoplastic resin, they are subjected to shear forces at a certain temperature, forming a fibrous network structure. During combustion, the PTFE network shrinks due to heat, preventing the melt from dripping. A layer of residual carbon forms on the surface of the material, blocking oxygen and achieving excellent flame retardancy and anti-drip properties.

[0012] The corresponding purpose of the present invention is achieved through the following technical solutions:

[0013] A fluorinated acrylate-coated anti-drip agent has a core-shell structure, wherein a high molecular weight fluoroethylene polymer serves as the core layer of the core-shell structure, accounting for 35-85 wt% of the weight of the entire anti-drip agent; a polymer formed by polymerizing an acrylate monomer and a fluorinated acrylate monomer serves as the shell layer of the core-shell structure, accounting for 65-15 wt% of the weight of the entire anti-drip agent, and the fluorinated acrylate monomer accounts for 5-30 wt% of the shell layer monomer.

[0014] More preferably, the core layer accounts for 50-70 wt% of the total weight of the anti-drip agent, and the shell layer accounts for 30-50 wt% of the total weight of the anti-drip agent. The inventors can adjust the shell thickness to 20-80 nm by adjusting the core-shell ratio.

[0015] The high molecular weight fluoroethylene polymer has an average molecular weight of 1,000,000 to 10,000,000 and is selected from homopolymers or copolymers of fluoroolefins such as chlorotrifluoroethylene, hexafluoropropylene, tetrafluoroethylene, and fluoroalkylethylene, or fluorinated polymers selected from polytetrafluoroethylene, hexafluoropropylene-tetrafluoroethylene copolymers, tetrafluoroethylene-ethylene copolymers, and tetrafluoroethylene-vinyl ether copolymers. The high molecular weight fluoroethylene polymer can be directly purchased as a concentrated dispersion on the market.

[0016] The acrylic acid ester polymer monomer is selected from one or more of the following: C1-4 alkyl acrylate and C1-4 alkyl methacrylate; more preferably, one or more of methyl methacrylate, butyl acrylate, methacrylonitrile, hydroxyethyl methacrylate, glycidyl methacrylate, isobornyl methacrylate, and methacrylic acid;

[0017] The fluorinated acrylic ester polymerization monomer is selected from one or more of the following: trifluoroethyl methacrylate, octafluoropentyl methacrylate, hexafluorobutyl methacrylate, and dodecafluoroheptyl methacrylate; trifluoroethyl methacrylate is more preferred, which is beneficial to the emulsion stability in the production process of high molecular weight fluoroethylene polymer anti-drip agent.

[0018] The anti-drip agent of the above composition can use as small a proportion of shell monomer as possible while ensuring that the anti-drip agent significantly improves the anti-drip performance of the substrate, thereby achieving sufficient shell coating and core-shell stability during processing.

[0019] The preparation method of the fluorinated acrylate-coated anti-dripping agent specifically comprises the following steps:

[0020] (1) ultrasonically pre-emulsifying all shell monomers and an emulsifier at an oil-water ratio of 1:1.2 to obtain a pre-emulsified emulsion;

[0021] (2) diluting the concentrated dispersion of the high molecular weight fluoroethylene polymer with deionized water, and then stirring and mixing with 1 / 10-1 / 8 of the pre-emulsified emulsion at 300-500 rpm, and adjusting the temperature to the reaction temperature range of 70-85°C;

[0022] (3) After reaching the reaction temperature, reduce the rotation speed to 120-150 rpm, add 2 / 3 of the initiator, react for 10-60 minutes, and then slowly add the remaining shell monomer pre-emulsion to the system dropwise. The addition time is controlled within 1-4 hours.

[0023] (4) After the dropwise addition is complete, the remaining 1 / 3 of the initiator is added and stirring is continued for 2-12 hours to obtain a milky white emulsion of a fluoroethylene polymer coated with a fluorinated acrylate;

[0024] (5) Raising the temperature to 70-90° C., adding a demulsifier to demulsify the reaction product under stirring, washing, and drying to obtain the anti-dripping agent with excellent core-shell stability.

[0025] More specifically: wherein the shell monomers in step (1) include acrylic ester polymer monomers and fluorinated acrylic ester polymer monomers, and during pre-emulsification, all the shell monomers are first ultrasonically pre-emulsified together with an emulsifier according to an oil-water weight ratio of 1:1.2, wherein the emulsifier accounts for 1-5% of the total weight of the shell monomers; further preferably, the emulsifier accounts for 3% of the total weight of the shell monomers.

[0026] The ultrasonic pre-emulsification conditions are as follows: an ultrasonic frequency range of 400w-800w, ultrasonic treatment for 30 minutes, wherein the working time and the rest time are 5s and 3s respectively.

[0027] The emulsifier used is preferably a combination of an ionic emulsifier, a nonionic emulsifier and a polymer emulsifier, wherein the ionic emulsifier is sodium lauryl sulfate, the nonionic emulsifier is dodecylphenol polyoxyethylene ether, and the polymer emulsifier is polyvinyl alcohol, and the weight ratio of the three is 1:2-3:4-5; the concentrated dispersion of the high molecular weight fluoroethylene polymer itself is unstable during polymerization, so the selection of the appropriate type and ratio of emulsifiers is the key to polymerization.

[0028] The ionic emulsifier is one or more of ionic emulsifiers such as sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and triethanolamine; the non-ionic emulsifier is one or more of non-ionic emulsifiers such as fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene polyoxypropylene ether, and sorbitan fatty acid ester; and the polymer emulsifier is one or more of polymer emulsifiers such as polyolefin polymers, polyvinyl pyrrolidone polymers, polyether polymers, polyvinyl alcohol polymers, and polyurethane polymers.

[0029] Ionic emulsifiers are more conducive to maintaining emulsion stability, but too much ionic emulsifier will cause the shell monomer to self-polymerize; and non-ionic emulsifiers need to be used alone in a large amount to maintain emulsion stability. Therefore, a large amount of non-ionic emulsifier is selected and a small amount of ionic emulsifier is added for compounding. The non-ionic emulsifier can be adjusted according to the core-shell ratio, and the amount used is 2-3 times that of the ionic emulsifier; the polymer emulsifier mainly plays the role of maintaining the stability of the emulsion suspension, and the amount used is larger, 4-5 times that of the ionic emulsifier. The inventors have achieved good emulsification effect by using the above-mentioned multiple emulsifiers for compounding. While ensuring the complete coating of the shell monomer, the stability of the emulsion can be effectively maintained. The above-mentioned compound emulsifiers are selected in a weight ratio of 1:2:5, and when the total addition amount is 3% of the weight of the shell monomer, the emulsion stability can be maintained while suppressing the heterogeneous nucleation of acrylate.

[0030] In step (2), the concentrated dispersion of the high molecular weight fluoroethylene polymer is diluted with deionized water to 10-17.5 wt %, and then stirred and mixed with the shell monomer pre-emulsified emulsion obtained in step (1) with a weight ratio of 1 / 10-1 / 8 at 300-500 rpm, and the reaction temperature is adjusted to 50-100° C. The high molecular weight fluoroethylene polymer dispersion has an average molecular weight of about 1 million to 10 million, a solid content of 60-62%, and an emulsion particle size of 100-300 nm.

[0031] After reaching the reaction temperature in step (3), the rotation speed is reduced to 120-150 rpm, 2 / 3 of the weight of the initiator is added, and after reacting for 10-60 minutes, the remaining shell monomer pre-emulsion is slowly added dropwise to the system, and the addition time is controlled to be 1-4 hours.

[0032] The amount of the initiator is 0.1-2% of the weight of the total shell monomers; the initiator is a free radical polymerization initiator such as azobisisobutyronitrile, potassium persulfate, ammonium persulfate, benzoyl peroxide, cumene hydroperoxide, hydrogen peroxide, etc.

[0033] The more preferred initiator is potassium persulfate, and the preferred reaction temperature is between 75° C. and 80° C. This temperature range is beneficial for maintaining the stability of the concentrated dispersion of the high molecular weight fluoroethylene polymer during the emulsion polymerization process.

[0034] The demulsifier is an inorganic salt such as sodium chloride, calcium chloride, magnesium sulfate, aluminum nitrate, etc. The size and shape of the anti-dripping agent particles obtained by using different demulsifiers are different, and different demulsifiers can be selected according to actual needs.

[0035] The demulsifier used in step (5) should be present in an amount of 10-30% by weight of the shell monomer. In initial production, the emulsion to be demulsified can be raised to the target temperature, and then the demulsifier dissolved in water is added dropwise until the emulsion breaks. This can further determine the appropriate demulsifier dosage.

[0036] During the processing of the anti-drip agent, the interaction between the acrylate in the shell and the high-molecular-weight fluoroethylene polymer in the core is enhanced by adding a fluorinated acrylate, thereby making the anti-drip agent more stable and less likely to fall off during processing. Therefore, the anti-drip agent is easier to mix and has good dispersibility during use, and can effectively improve the flame retardancy and anti-drip properties of the thermoplastic resin. The thermoplastic resin products added with the anti-drip agent of the present invention have a smooth surface and good appearance.

[0037] Based on the anti-dripping agent obtained above, the present invention further provides a thermoplastic resin product, which comprises, by weight: a) 100 parts of thermoplastic resin; b) 1 part of flame retardant; c) 1 part of ultraviolet absorber; d) 4 parts of toughening agent; f) 0.1-5 parts of anti-dripping agent;

[0038] If the amount of the anti-drip agent is less than 0.1 parts, it is difficult to achieve the anti-drip requirement; if it is greater than 5 parts, the mechanical properties of the material will be reduced and the melt viscosity will be too high, making it difficult to process. More preferably, it is 0.05-2 parts.

[0039] When using the anti-dripping agent, the anti-dripping agent can be mixed with the thermoplastic resin in advance and then added to the extruder together, or the resin and the anti-dripping agent can be added to the extruder through the pellet and powder barrels respectively for mixing. Taking polycarbonate as an example, the temperature range is set to 210°C for zone 1, 230°C for zone 2, and 250°C for zone 3.

[0040] The above-mentioned thermoplastic resin is selected from one or more composite resins of acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, high-impact styrene resin, acrylonitrile-ethyl acrylate-styrene copolymer resin, polycarbonate resin, polybutylene terephthalate, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polymethyl methacrylate, and polylactic acid resin.

[0041] Among the other components, flame retardants primarily include potassium 3-phenylsulfonylbenzenesulfonate, zinc borate, and dimethyl methylphosphonate. UV absorbers primarily include phenyl benzoate and 2-hydroxy-4-n-octyloxybenzophenone. Tougheners primarily include acrylate-silicon tougheners and acrylate-butadiene tougheners. Anti-drip agents, when used in conjunction with these flame retardants, can enhance their effectiveness. The addition of flame retardants can enhance self-extinguishing properties during combustion, thereby reducing dripping. Furthermore, the addition of anti-drip agents can help the molten material accumulate on the combustion surface, isolating it from oxygen and promoting flame retardancy. This combination of additives provides optimal results.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] Thermoplastic resin products added with the above-mentioned anti-drip agent have better applications in the construction industry and the automobile manufacturing industry. When facing high temperatures or even fire disasters, they can effectively prevent the occurrence and spread of fire, thereby improving safety. Compared with anti-drip agents coated with other materials, fluorine-containing anti-drip agents have better processing stability, which is beneficial to enhancing the dispersibility of the anti-drip agent in the polycarbonate substrate, thereby having better mechanical stability and reducing local defects of the material caused by processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 TEM photos of the polytetrafluoroethylene dispersion and the anti-dripping agent obtained in Example 1.

[0045] like Figure 1 As shown, the TEM image of the anti-dripping agent obtained in Example 1 (right) is compared with the TEM image of polytetrafluoroethylene (left). It can be found that a light-colored shell layer can be clearly seen in the coated polytetrafluoroethylene, and the size is significantly larger than that of pure polytetrafluoroethylene, which proves that an anti-dripping agent with a core-shell structure can be obtained by this scheme;

[0046] Figure 2 This is a graph showing the particle size change of the fluorinated anti-dripping agent as the core-shell ratio increases;

[0047] Figure 3 This is the EDS elemental analysis of the cross section of the fluorinated anti-drip agent blended with polycarbonate;

[0048] Figure 4 It is a combustion comparison diagram of pure polycarbonate and polycarbonate doped with the anti-drip agent of the present invention. DETAILED DESCRIPTION

[0049] The above contents of the present invention are described in further detail below by way of specific embodiments of the embodiment forms, but this should not be construed as limiting the scope of the above-mentioned theme of the present invention to the following examples. All technologies realized based on the above-mentioned contents of the present invention belong to the scope of the present invention. Unless otherwise specified, conventional prior art is adopted in the following examples. In the examples, if specific conditions are not specified, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0050] Example 1

[0051] A fluorinated acrylate-coated anti-drip agent having a core-shell structure, wherein a high molecular weight polytetrafluoroethylene dispersion serves as the core layer of the core-shell structure. The polytetrafluoroethylene dispersion used is Dongyue Company's DF-301, which has an average molecular weight of approximately 1 million to 10 million and a solid content of 62%, which accounts for 50% by weight of the entire anti-drip agent.

[0052] The shell monomers of the core-shell structure are methyl methacrylate, butyl methacrylate, methacrylic acid, and trifluoroethyl methacrylate, which account for 50wt% of the total weight of the anti-drip agent, and trifluoroethyl methacrylate accounts for 5wt% of the shell part, while methyl methacrylate, butyl methacrylate, and methacrylic acid account for 55wt%, 30wt% and 10wt% respectively.

[0053] The preparation method of the fluorinated acrylate-coated anti-dripping agent specifically comprises the following steps:

[0054] (1) ultrasonically pre-emulsifying all shell monomers and an emulsifier at an oil-water ratio of 1:1.2 to obtain a pre-emulsified emulsion;

[0055] The emulsifier accounts for 3% of the weight of the shell monomer, and the weight ratio of the ionic emulsifier, the non-ionic emulsifier and the polymer emulsifier is 1:2:5, and the non-ionic emulsifier is dodecylphenol polyoxyethylene ether, the ionic emulsifier is sodium lauryl sulfate, and the polymer emulsifier is PVA-1799;

[0056] (2) The concentrated dispersion of the high molecular weight polytetrafluoroethylene polymer was diluted with deionized water to a weight ratio of 12.5%, and then mixed with 1 / 8 of the weight of the pre-emulsified emulsion at 500 rpm, and the reaction temperature was adjusted to 75°C;

[0057] (3) After reaching the reaction temperature, the rotation speed was reduced to 120 rpm, and 2 / 3 of potassium persulfate was added as an initiator; after reacting for 30 minutes, the remaining pre-emulsified emulsion was slowly added dropwise to the system, and the addition time was controlled within 4 hours;

[0058] (4) After the addition is complete, the remaining 1 / 3 of potassium persulfate is added and stirring is continued for 2 hours to obtain a milky white emulsion of polytetrafluoroethylene coated with fluorinated acrylate;

[0059] The total amount of the above initiators is 1% of the total shell monomer mass;

[0060] (5) The temperature is raised to 80° C., and barium chloride as a demulsifier is added under stirring to demulsify the reaction product, wash it, and dry it to obtain the anti-dripping agent with excellent core-shell stability, wherein the amount of barium chloride is 20% of the total shell monomer mass.

[0061] The specific performance of the anti-drip agent composed above is as follows: the usage amount of the shell monomer is the same as that of the core layer polytetrafluoroethylene seed, and the proportion is high. When the same dosage of anti-drip agent is used, the proportion of effective polytetrafluoroethylene anti-drip components will decrease, but it is beneficial to the dispersion of polytetrafluoroethylene anti-drip agent, and the addition of fluorinated acrylate is beneficial to maintaining the stability of the shell structure.

[0062] The inventors further provide an application of the above-mentioned anti-dripping agent, specifically providing a thermoplastic resin product, which includes 100 parts by weight of polycarbonate, 1 part by weight of potassium 3-phenylsulfonylbenzenesulfonate as a flame retardant, 1 part by weight of phenyl benzoate as a UV absorber and 0.5 part by weight of the above-mentioned anti-dripping agent.

[0063] The mixture is blended and extruded into granules through a twin-screw extruder for subsequent molding. During molding, different molding processes can be selected according to different usage environments.

[0064] Example 2

[0065] A fluorinated acrylate-coated anti-drip agent, the anti-drip agent having a core-shell structure, wherein a high molecular weight polytetrafluoroethylene dispersion serves as the core layer of the core-shell structure. The polytetrafluoroethylene dispersion used is Dongyue Company's DF-301, which has an average molecular weight of approximately 1 million to 10 million and a solid content of 62%, which accounts for 63.5wt% of the total weight of the anti-drip agent.

[0066] The shell part of the core-shell structure is composed of methyl methacrylate, butyl methacrylate, methacrylic acid, and trifluoroethyl methacrylate, which accounts for 37.5wt% of the entire anti-dripping agent, and trifluoroethyl methacrylate accounts for 5wt% of the shell part, while methyl methacrylate, butyl methacrylate, and methacrylic acid account for 55wt%, 30wt% and 10wt% respectively.

[0067] The preparation method of the fluorinated acrylate-coated anti-dripping agent specifically comprises the following steps:

[0068] (1) ultrasonically pre-emulsifying all shell monomers and an emulsifier at an oil-water ratio of 1:1.2 to obtain a pre-emulsified emulsion;

[0069] The emulsifier accounts for 2.5% of the weight of the shell monomer, and the weight ratio of the ionic emulsifier, the non-ionic emulsifier and the polymer emulsifier is 1:2:5, and the non-ionic emulsifier is dodecylphenol polyoxyethylene ether, the ionic emulsifier is sodium lauryl sulfate, and the polymer emulsifier is PVA-1799;

[0070] (2) The concentrated dispersion of high molecular weight polytetrafluoroethylene polymer was diluted with deionized water to a weight ratio of 15%, and then mixed with 1 / 8 of the pre-emulsified emulsion at 500 rpm, and the reaction temperature was adjusted to 75°C;

[0071] (3) After reaching the reaction temperature, the rotation speed was reduced to 120 rpm, and 2 / 3 potassium persulfate was added as an initiator; after reacting for 30 minutes, the remaining shell monomer pre-emulsion was slowly added dropwise to the system, and the addition time was controlled within 3 hours;

[0072] (4) After the dropwise addition is complete, the remaining 1 / 3 of potassium persulfate is added and stirring is continued for 3 hours to obtain a milky white emulsion of polytetrafluoroethylene coated with fluorinated acrylate;

[0073] The total amount of the above initiators is 1% of the total shell monomer mass;

[0074] (5) The temperature is raised to 80° C., and barium chloride as a demulsifier is added under stirring to demulsify the reaction product, wash it, and dry it to obtain the anti-dripping agent with excellent core-shell stability, wherein the amount of barium chloride is 20% of the total shell monomer mass.

[0075] The specific performance of the anti-dripping agent composed above is as follows: the proportion of the shell monomer is more balanced than that of the core layer polytetrafluoroethylene seed, which not only ensures the complete coating of the high molecular weight polytetrafluoroethylene in the core, but also increases the polytetrafluoroethylene content per unit mass, thereby enhancing the modification effect of the anti-dripping agent.

[0076] For the corresponding thermoplastic resin product, the amount of the anti-drip agent is 1 part, and the amounts of the other components and the preparation process are the same as in Example 1. The mixture is blended by a twin-screw extruder, and extrusion granulation can be performed for subsequent molding processing. During the molding process, different molding processes can be selected according to different usage environments.

[0077] Example 3

[0078] A fluorinated acrylate-coated anti-drip agent having a core-shell structure, wherein a high-molecular-weight polytetrafluoroethylene dispersion serves as the core layer of the core-shell structure. The polytetrafluoroethylene dispersion used is Dongyue Company's DF-301, which has an average molecular weight of approximately 1 million to 10 million and a solid content of 62%, which accounts for 83.3% by weight of the entire anti-drip agent.

[0079] The shell part of the core-shell structure is composed of methyl methacrylate, butyl methacrylate, methacrylic acid, and trifluoroethyl methacrylate, which accounts for 16.6wt% of the total weight of the anti-drip agent, and trifluoroethyl methacrylate accounts for 5wt% of the shell part, while methyl methacrylate, butyl methacrylate, and methacrylic acid account for 55wt%, 30wt% and 10wt% respectively.

[0080] The preparation method of the fluorinated acrylate-coated anti-dripping agent specifically comprises the following steps:

[0081] (1) All shell monomers and emulsifiers are ultrasonically pre-emulsified at an oil-water ratio of 1:1.2 to obtain a pre-emulsified emulsion.

[0082] The emulsifier accounts for 2% of the weight of the shell monomer, wherein the weight ratio of the ionic emulsifier, the nonionic emulsifier and the polymer emulsifier is 1:2:5, and the nonionic emulsifier is dodecylphenol polyoxyethylene ether, the ionic emulsifier is sodium lauryl sulfate, and the polymer emulsifier is PVA-1799;

[0083] (2) diluting the concentrated dispersion of high molecular weight polytetrafluoroethylene polymer with deionized water to a weight ratio of 17.5%, and then stirring and mixing with 1 / 8 of the pre-emulsified emulsion at 500 rpm, and adjusting the reaction temperature to 75°C;

[0084] (3) After reaching the reaction temperature, the rotation speed was reduced to 120 rpm, and 2 / 3 potassium persulfate was added as an initiator; after reacting for 30 minutes, the remaining shell monomer pre-emulsion was slowly added dropwise to the system, and the addition time was controlled within 2 hours;

[0085] (4) After the dropwise addition is complete, the remaining 1 / 3 of potassium persulfate is added and stirring is continued for 4 hours to obtain a milky white emulsion of polytetrafluoroethylene coated with fluorinated acrylate;

[0086] The total amount of the above initiators is 1% of the total shell monomer mass;

[0087] (5) The temperature is raised to 80° C., and barium chloride as a demulsifier is added under stirring to demulsify the reaction product, wash it, and dry it to obtain the anti-dripping agent with excellent core-shell stability, wherein the amount of barium chloride is 20% of the total shell monomer mass.

[0088] The specific performance of the anti-drip agent composed above is as follows: the proportion of shell monomers is lower than that of core polytetrafluoroethylene seeds. When the same dosage of anti-drip agent is used, the proportion of effective polytetrafluoroethylene anti-drip components will increase, but the smaller shell monomers cannot ensure that the high molecular weight polytetrafluoroethylene is completely coated, which may lead to a decrease in dispersibility.

[0089] For the corresponding thermoplastic resin product, the amount of the anti-drip agent is 2 parts, and the amounts of the other components and the preparation process are the same as in Example 1. The mixture is blended by a twin-screw extruder, and extrusion granulation can be performed for subsequent molding processing. During the molding process, different molding processes can be selected according to different usage environments.

[0090] The inventors conducted relevant tests on the anti-dripping agent prepared in the above embodiment, and the results are as follows:

[0091] like Figure 1 As shown, the TEM image of the anti-dripping agent obtained in Example 1 is compared with the TEM image of polytetrafluoroethylene. It can be found that a light-colored shell layer can be clearly seen in the coated polytetrafluoroethylene, and the size is significantly larger than that of pure polytetrafluoroethylene, which proves that an anti-dripping agent with a core-shell structure can be obtained by this scheme;

[0092] Figure 2 The particle size distribution diagram of the anti-drip agent obtained with different core-shell ratios (5:1 to 5:5 correspond to Example 3-1, respectively). It can be seen that when the core-shell ratio changes from 5:1 to 5:5, the obtained anti-drip particle size also gradually increases; the main function of the shell layer of the polytetrafluoroethylene core-shell anti-drip agent is to promote the dispersion of the polytetrafluoroethylene anti-drip agent. If the thickness is too thick, the ratio of the core-shell layer will be reduced. Under the same dosage, the proportion of the polytetrafluoroethylene core layer, which plays a major role, will be reduced, and the flame retardant and anti-drip effect will be worse; the thickness range is controlled by different core-shell ratios, and the shell thickness can generally be adjusted to 20-80 nm.

[0093] At the same time, it can be seen that the technical solutions of Examples 1 and 2 can both meet the requirements of complete coating of the core layer and improved dispersibility. Among them, since the shell layer accounts for a smaller proportion in the 5:3 ratio in Example 2, the anti-dripping agent of the same quality has more components that are conducive to the anti-dripping effect in the 5:3 ratio, which is more advantageous than the 5:5 ratio in Example 1.

[0094] Comparative Example 1

[0095] A fluorinated acrylate-coated anti-drip agent having a core-shell structure, wherein a high molecular weight polytetrafluoroethylene dispersion serves as the core layer of the core-shell structure. The polytetrafluoroethylene dispersion used is Dongyue Company's DF-301, which has an average molecular weight of approximately 1 million to 10 million and a solid content of 62%, which accounts for 50% by weight of the entire anti-drip agent.

[0096] The shell part of the core-shell structure is composed of methyl methacrylate, butyl methacrylate and methacrylic acid, which accounts for 50wt% of the entire anti-dripping agent. Methyl methacrylate, butyl methacrylate and methacrylic acid account for 60wt%, 30wt% and 10wt% respectively.

[0097] The preparation method of the non-fluorinated acrylate-coated anti-dripping agent specifically comprises the following steps:

[0098] (1) ultrasonically pre-emulsifying all shell monomers and an emulsifier at an oil-water ratio of 1:1.2 to obtain a pre-emulsified emulsion;

[0099] The emulsifier accounts for 3% of the weight of the shell monomer, and the weight ratio of the ionic emulsifier, the non-ionic emulsifier and the polymer emulsifier is 1:2:5, and the non-ionic emulsifier is dodecylphenol polyoxyethylene ether, the ionic emulsifier is sodium lauryl sulfate, and the polymer emulsifier is PVA-1799;

[0100] (2) diluting the concentrated dispersion of high molecular weight polytetrafluoroethylene polymer with deionized water to a weight ratio of 10-20%, and then stirring and mixing with 1 / 8 weight of the pre-emulsified emulsion at 500 rpm, and adjusting the reaction temperature to 75°C;

[0101] (3) After reaching the reaction temperature, the rotation speed was reduced to 120 rpm, and 2 / 3 of potassium persulfate was added as an initiator; after reacting for 30 minutes, the remaining pre-emulsified emulsion was slowly added dropwise to the system, and the addition time was controlled within 4 hours;

[0102] (4) After the addition is complete, the remaining 1 / 3 of potassium persulfate is added and stirring is continued for 2 hours to obtain a milky white emulsion of polytetrafluoroethylene coated with fluorinated acrylate;

[0103] The total amount of the above initiators is 1% of the total shell monomer mass;

[0104] (5) The temperature is raised to 80° C., and barium chloride as a demulsifier is added under stirring to demulsify the reaction product, wash it, and dry it to obtain the anti-dripping agent with excellent core-shell stability, wherein the amount of barium chloride is 20% of the total shell monomer mass.

[0105] The anti-dripping agent of the above composition may face the risk of shell shedding during processing, as the shell acrylate is a non-fluorine system, compared with the fluorine-containing acrylate system in the embodiment.

[0106] The application, composition, dosage and processing method of the anti-dripping agent obtained in the above comparative example are the same as those in Example 1.

[0107] Experimental Example 1

[0108] The anti-dripping agent produced by Experimental Example 1 and Comparative Example 1 was blended with polycarbonate according to the ratio. The temperature range was set to 210°C in zone 1, 230°C in zone 2, and 250°C in zone 3. The rotation speed was 50 rpm. After blending for 10 minutes, modified polycarbonate strips of uniform thickness were extruded.

[0109] The material strands are sheared and granulated in a pelletizer. The modified polycarbonate pellets are evenly spread into a mold and pressed into sheets using a hot press. The hot pressing process is divided into two stages: first, the press is heated to 200°C, pressurized to 10 MPa for 5 minutes, and then the pressure is released and the air is released. This process is repeated 5-10 times. The temperature is then raised to 220°C, stabilized for 30 minutes, and then pressurized to 20 MPa for 60 minutes. The sheet is then cooled naturally to room temperature under pressure, the pressure is released, and the sheet is cut to the test size.

[0110] The modified polycarbonate strips were broken by liquid nitrogen and analyzed by EDS. Figure 3 F element distribution diagram of the cross section. Figure 3 The fluorine is uniformly distributed in the shell layer of the obtained anti-dripping agent core-shell structure, indicating that the fluorine-containing acrylate is successfully composited and uniformly distributed in the shell structure.

[0111] The combustion test is divided into primary ignition and secondary ignition, both conducted using a Bunsen burner. The flame height of the Bunsen burner is 20mm. After 10 seconds of ignition, the flame is removed and the time of burning, melting and dripping begins to be recorded. After the primary combustion is extinguished, the secondary ignition is immediately performed. Similarly, after 10 seconds of ignition, the flame is removed and the time of burning, melting and dripping begins to be recorded.

[0112] The test board size is processed and cut according to the standard of 200mm*15mm*3mm; the material strips with similar thickness are selected for testing, and the length is 200mm.

[0113] The test results are as follows:

[0114] The combustion test of the polycarbonate sheet modified with the non-fluorine anti-drip agent in Comparative Example 1 and the polycarbonate sheet modified with the fluorine-containing anti-drip agent in Example 1 is as follows: Figure 4 As shown, the polycarbonate plate modified with the non-fluorine anti-drip agent in Comparative Example 1 melted and dripped 10 seconds after the initial ignition, and melted and dripped 14 seconds after the secondary ignition; while the polycarbonate plate modified with the fluorine-containing anti-drip agent in Example 1 melted and dripped 25 seconds after the initial ignition, and melted and dripped 28 seconds after the secondary ignition. Compared with the polycarbonate modified with the non-fluorine anti-drip agent in Comparative Example 1, the melt dripping time was more than doubled.

[0115] The combustion test of the polycarbonate strip modified with the non-fluorine anti-drip agent in Comparative Example 1 and the polycarbonate strip modified with the fluorine-containing anti-drip agent in Example 1 is as follows: Figure 4As shown, the polycarbonate strip modified with the non-fluorine anti-drip agent in Comparative Example 1 melted and dripped 6 seconds after the initial ignition, and self-extinguished in 9 seconds after the secondary ignition; while the polycarbonate strip modified with the fluorine-containing anti-drip agent in Example 1 self-extinguished 30 seconds after the initial ignition without melt dripping, and self-extinguished quickly after the flame was removed after the secondary ignition. Compared with the polycarbonate modified with the non-fluorine anti-drip agent in Comparative Example 1, the flame retardant and anti-drip properties are significantly improved;

[0116] The results show that the polycarbonate doped with the same anti-drip agent as in this application has less material loss after combustion and has a relatively better anti-drip effect when in a burning state. When facing high temperatures or even fire disasters, it can effectively avoid the occurrence and spread of fire, thereby improving safety.

[0117] The above embodiments will help those skilled in the art to better understand the present invention. The implementation methods of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A fluorinated acrylate-coated anti-dripping agent, characterized in that: The anti-drip agent has a core-shell structure, wherein a high molecular weight fluoroethylene polymer serves as the core layer of the core-shell structure, accounting for 35-85 wt % of the weight of the entire anti-drip agent; a polymer formed by polymerization of an acrylate monomer and a fluorinated acrylate monomer serves as the shell layer of the core-shell structure, accounting for 65-15 wt % of the weight of the entire anti-drip agent, and the fluorinated acrylate monomer accounts for 5-30 wt % of the shell layer monomer; The preparation method comprises the following steps: (1) All shell monomers and emulsifiers are ultrasonically pre-emulsified at an oil-water ratio of 1:1.2 to obtain a pre-emulsified emulsion; (2) diluting the concentrated dispersion of the high molecular weight fluoroethylene polymer with deionized water, and then mixing with 1 / 10-1 / 8 of the pre-emulsified emulsion at 300-500 rpm, and adjusting to the reaction temperature, the reaction temperature range is 70-85°C; (3) After reaching the reaction temperature, reduce the speed to 120-150 rpm, add 2 / 3 of the initiator, react for 10-60 minutes, and then slowly add the remaining shell monomer pre-emulsion to the system dropwise. The addition time is controlled within 1-4 hours. (4) After the addition is complete, the remaining 1 / 3 of the initiator is added and stirring is continued for 2-12 hours to obtain a milky white emulsion of a fluoroethylene polymer coated with a fluorinated acrylate; (5) heating the mixture to 70-90° C., adding a demulsifier to demulsify the reaction product under stirring, washing, and drying the reaction product to obtain the anti-dripping agent having excellent core-shell stability; The emulsifier used is a compound of an ionic emulsifier, a nonionic emulsifier and a polymer emulsifier, and the weight ratio of the three is 1:2-3:4-5.

2. The fluorinated acrylate-coated anti-dripping agent according to claim 1, characterized in that: The core layer accounts for 50-70 wt% of the total weight of the anti-drip agent, and the shell layer accounts for 30-50 wt% of the total weight of the anti-drip agent.

3. The fluorinated acrylate-coated anti-dripping agent according to claim 1, characterized in that: The high molecular weight fluoroethylene polymer has an average molecular weight of 1 million to 10 million and is selected from homopolymers or copolymers of monochlorotrifluoroethylene, hexafluoropropylene, tetrafluoroethylene, and fluoroalkylethylene; the acrylic acid ester polymerization monomer is selected from one or more of the following: C1-4 alkyl acrylate, C1-4 alkyl methacrylate; the fluorine-containing acrylic acid ester polymerization monomer is selected from one or more of the following: trifluoroethyl methacrylate, octafluoropentyl methacrylate, hexafluorobutyl methacrylate, and dodecafluoroheptyl methacrylate.

4. The fluorinated acrylate-coated anti-dripping agent according to claim 1 or 3, characterized in that: The acrylic acid ester polymerization monomer is selected from one or more of methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, glycidyl methacrylate, and isobornyl methacrylate; the fluorine-containing acrylic acid ester polymerization monomer is selected from trifluoroethyl methacrylate.

5. The method for preparing the fluorinated acrylate-coated anti-dripping agent according to claim 1, characterized in that: The specific steps include: (1) All shell monomers and emulsifiers are ultrasonically pre-emulsified at an oil-water ratio of 1:1.2 to obtain a pre-emulsified emulsion; (2) diluting the concentrated dispersion of the high molecular weight fluoroethylene polymer with deionized water, and then mixing with 1 / 10-1 / 8 of the pre-emulsified emulsion at 300-500 rpm, and adjusting to the reaction temperature, the reaction temperature range is 70-85°C; (3) After reaching the reaction temperature, reduce the speed to 120-150 rpm, add 2 / 3 of the initiator, react for 10-60 minutes, and then slowly add the remaining shell monomer pre-emulsion to the system dropwise. The addition time is controlled within 1-4 hours. (4) After the addition is complete, the remaining 1 / 3 of the initiator is added and stirring is continued for 2-12 hours to obtain a milky white emulsion of a fluoroethylene polymer coated with a fluorinated acrylate; (5) heating the mixture to 70-90° C., adding a demulsifier to demulsify the reaction product under stirring, washing, and drying the reaction product to obtain the anti-dripping agent having excellent core-shell stability; The emulsifier used is a compound of an ionic emulsifier, a nonionic emulsifier and a polymer emulsifier, and the weight ratio of the three is 1:2-3:4-5.

6. The method for preparing the fluorinated acrylate-coated anti-dripping agent according to claim 5, wherein: The shell monomers in step (1) include acrylic acid ester polymer monomers and fluorinated acrylic acid ester polymer monomers, and the emulsifier accounts for 1-5% of the total weight of the shell monomers during pre-emulsification; the ultrasonic pre-emulsification conditions are an ultrasonic frequency range of 400w-800w, ultrasonication for 30min, wherein the working time and the rest time are 5s and 3s respectively.

7. The method for preparing the fluorinated acrylate-coated anti-dripping agent according to claim 6, wherein: The ionic emulsifier is one or more of sodium lauryl sulfate, sodium dodecylbenzene sulfonate, and sodium lauryl sulfonate; the nonionic emulsifier is one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene polyoxypropylene ether, and sorbitan fatty acid ester; the polymer emulsifier is polyvinyl pyrrolidone or polyvinyl alcohol.

8. The method for preparing the fluorinated acrylate-coated anti-dripping agent according to claim 5, wherein: In step (2), the concentrated dispersion of the high molecular weight fluoroethylene polymer is diluted with deionized water to 10-17.5 wt %, and then stirred and mixed with the shell monomer pre-emulsified emulsion obtained in step (1) with a weight ratio of 1 / 10-1 / 8 at 300-500 rpm, and the reaction temperature is adjusted to 50-100° C. The high molecular weight fluoroethylene polymer dispersion has an average molecular weight of 1 million to 10 million, a solid content of 60-62%, and an emulsion particle size of 100-300 nm.

9. The method for preparing the fluorinated acrylate-coated anti-dripping agent according to claim 5, wherein: The amount of the initiator used is 0.1-2% of the weight of all shell monomers; the initiator is one of azobisisobutyronitrile, potassium persulfate, ammonium persulfate, benzoyl peroxide, cumene hydroperoxide, and hydrogen peroxide; the demulsifier is one of sodium chloride, calcium chloride, magnesium sulfate, and aluminum nitrate.

10. A thermoplastic resin product containing the fluorinated acrylate-coated anti-drip agent according to claim 1, characterized in that: The invention comprises, by weight: a) 100 parts of thermoplastic resin; b) 1 part of flame retardant; c) 1 part of ultraviolet absorber; d) 4 parts of toughening agent; f) 0.1-5 parts of anti-dripping agent; The thermoplastic resin is selected from one or more of acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, high-impact styrene resin, acrylonitrile-ethyl acrylate-styrene copolymer resin, polycarbonate resin, polybutylene terephthalate, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polymethyl methacrylate, and polylactic acid resin.

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