Preparation method of organic silicon coated PTFE emulsion anti-dripping agent

Abstract

The invention discloses a preparation method of an organosilicon-coated PTFE (polytetrafluoroethylene) emulsion anti-dripping agent, which comprises the following steps: uniformly mixing and stirring PTFE emulsion and an emulsifier, and adding organosilicon under the condition of high-speed stirring to obtain the organosilicon-coated PTFE emulsion anti-dripping agent, the addition amount of the organic silicon accounts for 30-40% of the total mass of the anti-dripping agent, and the addition amount of the emulsifier accounts for 1-3% of the total mass of the anti-dripping agent. On the basis of physical coating, the surface of PTFE is coated with organic silicon of a specific type, the anti-dripping agent with good dispersity is prepared, chemical reaction is not involved in the whole process, no waste water is generated, the process is simple, and energy consumption is low.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a method for preparing an organosilicon-coated PTFE emulsion anti-drip agent. Background Art

[0002] Plastic products are prone to molten dripping when burning, which can cause the fire to spread. In order to improve the flame retardant properties of plastics, it is necessary to add anti-drip agents to the plastics. Anti-drip agents are made of polytetrafluoroethylene (PTFE) of different molecular weights through special modification. When added to the formula of engineering plastic flame retardants, they play a role in increasing melt strength and bending modulus, thereby improving the flame retardancy of the product and preventing dripping caused by combustion.

[0003] There are three main types of polytetrafluoroethylene used as an anti-drip agent: emulsion type, pure powder type, and coated type. Emulsion anti-drip agent is a suspended emulsion formed by dispersing polytetrafluoroethylene in water through the action of a dispersant. However, the temperature resistance of water is limited, which makes the PTFE emulsion easily lose water and agglomerate during the extrusion process. This causes uneven dispersion. Pure powder anti-drip agent is pure polytetrafluoroethylene powder. Since polytetrafluoroethylene itself is easy to agglomerate and has poor compatibility with other plastics, pure powder anti-drip agent has the problem of poor dispersion and is seldom used. Coated anti-drip agent is a layer of styrene-acrylonitrile copolymer SAN or polymethyl methacrylate PMMA, polystyrene PS and other materials coated on the outer layer of polytetrafluoroethylene PTFE, so that the anti-drip agent can be well dispersed in the resin.

[0004] Patent application number CN202010233099.5 discloses a method for preparing a silicone-coated polytetrafluoroethylene anti-drip agent; this method requires surface grafting treatment of polytetrafluoroethylene, which is difficult to process and complicated to prepare. Patent publication number CN115232313A discloses a method for preparing a siloxane-terminated coated anti-drip agent. The silane coupling agent is catalyzed in a solvent system to coat the PTFE. The above reaction will release methanol as a harmful byproduct, and will produce wastewater problems, which are not environmentally friendly and have high energy consumption. The anti-drip agent prepared in addition is not dry, easy to agglomerate, and poorly dispersed. Based on the above-mentioned problems, it is necessary to provide a new coated PTFE emulsion anti-drip agent. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a method for preparing a silicone-coated PTFE emulsion anti-drip agent is provided. The method is based on physical coating, and a specific type of silicone is coated on the surface of PTFE to obtain an anti-drip agent with good dispersibility. The whole process does not involve chemical reactions, no wastewater is generated, the process is simple, and the energy consumption is low.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A method for preparing a silicone-coated PTFE emulsion anti-drip agent comprises the following steps:

[0008] The PTFE emulsion and the emulsifier are mixed and stirred evenly, and organic silicon is added under high-speed stirring to obtain the anti-drip agent; the added amount of organic silicon accounts for 30-40% of the total mass of the anti-drip agent, and the amount of the emulsifier accounts for 1-3% of the total mass of the anti-drip agent.

[0009] Preferably, the solid content of the PTFE emulsion is 50-70%.

[0010] Preferably, the emulsifier is one of isomeric tridecyl alcohol polyoxyethylene ether 1305 and isomeric tridecyl alcohol polyoxyethylene ether 1308, or a mixture of the two.

[0011] Preferably, the organosilicon is a mixture of one or more of methyl silicone oil, phenyl silicone oil, organosilicon resin FCA-117, organosilicon resin DC8008, and organosilicon resin KR-2710.

[0012] Preferably, the viscosity of the methyl silicone oil is 1000 mPa·s; the viscosity of the phenyl silicone oil is 500 mPa·s.

[0013] Preferably, the added amount of the emulsifier is 1-2% of the total mass of the anti-drip agent.

[0014] Preferably, the stirring speed of the high-speed stirring is 400-600 r / min.

[0015] Preferably, the dropping speed of the silicone is 4-6 g / min.

[0016] Preferably, after the addition of the organosilicon is completed, stirring is continued for 10-20 minutes.

[0017] Preferably, the temperature when the organosilicon is added dropwise is 35-45°C.

[0018] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0019] 1. The present invention adopts a specific emulsifier to mix with PTFE emulsion, and then adds a specific liquid silicone into the system at a certain temperature and a certain speed for stirring and coating. The above process belongs to physical coating, not chemical reaction coating, and the operation is simple. The obtained anti-drip agent has better dispersibility in the matrix when used.

[0020] 2. The liquid silicone used in the present invention has better heat resistance. It coats PTFE to form a stable coating layer on the surface of PTFE particles, which improves the dispersibility of the emulsion and prevents the matrix and the anti-drip agent from being evenly dispersed in the silicone during screw extrusion, without causing agglomeration. In addition, the liquid silicone has a synergistic flame retardant effect. The anti-drip agent prepared has good flame retardant properties when added in a small amount. In addition, the liquid silicone has a good lubricating effect, which can eliminate the occurrence of outlet expansion and strip breakage during PC extrusion granulation.

[0021] 3. During coating, the present invention uses a specific emulsifier to greatly improve the compatibility of liquid silicone and PTFE emulsion, thereby achieving better coating, and the obtained anti-drip agent has better dispersibility. Moreover, the coating method provided by the present invention has mild conditions, no wastewater is generated, and the production efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 Schematic diagram of the outlet morphology when the anti-drip agent of Example 1 and Comparative Example 1 is blended with PC for extrusion, wherein (a) is the material to which the anti-drip agent of Comparative Example 10 is added; (b) is the material to which the anti-drip agent of Example 1 is added. DETAILED DESCRIPTION

[0024] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0025] The sources of raw materials used in the following examples and comparative examples are shown in Table 1.

[0026] Table 1

[0027]

[0028] Example 1

[0029] A method for preparing a silicone-coated PTFE emulsion anti-drip agent comprises the following steps:

[0030] In a 1L three-necked flask equipped with heating and tetrafluoroethylene stirring, add 300g PTFE emulsion (solid content is 50wt%), start stirring, add 3g emulsifier 1305 under stirring conditions of 500r / min, raise the temperature to 40°C, and add 150g methyl silicone oil (viscosity is 1000mPa·s) to the three-necked flask under constant temperature conditions. The methyl silicone oil is added dropwise within 30min, and then stirring and emulsifying is continued for 15min to obtain a silicone-coated PTFE emulsion anti-drip agent.

[0031] Example 2

[0032] A method for preparing a silicone-coated PTFE emulsion anti-drip agent comprises the following steps:

[0033] In a 1L three-necked flask equipped with heating and tetrafluoroethylene stirring, add 300g PTFE emulsion (solid content is 50wt%), start stirring, add 4g emulsifier 1308 under stirring conditions of 500r / min, raise the temperature to 40°C, and add 150g phenyl silicone oil (viscosity is 500mPa·s) to the three-necked flask under constant temperature conditions. The phenyl silicone oil is added dropwise within 30min, and then stirring and emulsifying is continued for 15min to obtain a silicone-coated PTFE emulsion anti-drip agent.

[0034] Example 3

[0035] A method for preparing a silicone-coated PTFE emulsion anti-drip agent comprises the following steps:

[0036] In a 1L three-necked flask equipped with heating and tetrafluoroethylene stirring, add 300g PTFE emulsion (solid content is 50wt%), start stirring, add 3g emulsifier 1308 under stirring conditions of 500r / min, raise the temperature to 40°C, and add 150g methoxy-terminated phenyl silsesquioxide FCA-117 to the three-necked flask under constant temperature conditions. The methoxy-terminated phenyl silsesquioxide FCA-117 is added dropwise within 30min, and then stirring and emulsifying is continued for 15min to obtain a silicone-coated PTFE emulsion anti-drip agent.

[0037] Example 4

[0038] A method for preparing a silicone-coated PTFE emulsion anti-drip agent comprises the following steps:

[0039] In a 1L three-necked flask equipped with heating and tetrafluoroethylene stirring, add 300g PTFE emulsion (solid content is 50wt%), start stirring, add 3g emulsifier 1308 under stirring condition of 500r / min, raise the temperature to 40°C, and add 150g trimethylphenylsilsesquioxane silicone DC 8008 to the three-necked flask under constant temperature condition. The trimethylphenylsilsesquioxane silicone DC 8008 is added dropwise within 30min, and then stirring and emulsifying is continued for 20min to obtain a silicone-coated PTFE emulsion anti-drip agent.

[0040] Example 5

[0041] A method for preparing a silicone-coated PTFE emulsion anti-drip agent comprises the following steps:

[0042] In a 1L three-necked flask equipped with heating and tetrafluoroethylene stirring, add 300g PTFE emulsion (solid content is 50wt%), start stirring, add 4.5g emulsifier 1305 under stirring conditions of 500r / min, raise the temperature to 40°C, and add 150g of methylphenyl series liquid silicone KR-2710 to the three-necked flask under constant temperature conditions. The methylphenyl series liquid silicone KR-2710 is added dropwise within 30min, and then stirring and emulsifying is continued for 20min to obtain a liquid silicone-coated PTFE emulsion anti-drip agent.

[0043] In order to better verify that the anti-drip agent of the present invention has a better effect, multiple comparative examples are given below based on Example 1 for further explanation.

[0044] Comparative Example 1

[0045] Compared with Example 1, the added amount of the emulsifier is 12 g, and the other conditions are the same as those in Example 1.

[0046] Comparative Example 2

[0047] Compared with Example 1, the added amount of the emulsifier is 1 g, and the other conditions are the same as those in Example 1.

[0048] Comparative Example 3

[0049] Compared with Example 1, Tween 80 was used to replace the emulsifier 1305, and other conditions were the same as those in Example 1.

[0050] Comparative Example 4

[0051] Compared with Example 1, the added amount of silicone is 120 g, and other conditions are the same as Example 1.

[0052] Comparative Example 5

[0053] Compared with Example 1, the added amount of silicone is 210 g, and other conditions are the same as Example 1.

[0054] Comparative Example 6

[0055] Compared with Example 1, hydrogen-containing silicone oil is used to replace methyl silicone oil, and other conditions are the same as those in Example 1.

[0056] Comparative Example 7

[0057] Compared with Example 1, the addition temperature of the silicone is 55° C., and other conditions are the same as those in Example 1.

[0058] Comparative Example 8

[0059] Compared with Example 1, the dropping speed of the silicone is 8 g / min, and the other conditions are the same as those in Example 1.

[0060] Comparative Example 9

[0061] Ordinary PTFE emulsion (FR302W) anti-drip agent (solid content is 50wt%).

[0062] Comparative Example 10

[0063] The commercially available SAN-coated polytetrafluoroethylene anti-drip agent has a mass fraction of polytetrafluoroethylene of 50%.

[0064] Outlet expansion test:

[0065] Application Example 1

[0066] The liquid silicone-coated PTFE emulsion anti-drip agent of Example 1 and the SAN-coated polytetrafluoroethylene anti-drip agent (the effective content of polytetrafluoroethylene is 50wt%) in Comparative Example 10 were added in an amount of 0.625wt% and 0.5wt% respectively, mixed with PC and perfluorobutyl sulfonate (the addition amount is 0.1wt%), and a twin-screw extruder (the melting section temperature is 260°C) was used for blending, stranding, and air-cooling pelletizing. The outlet conditions were observed, as shown in detail. Figure 1 shown.

[0067] from Figure 1 It can be seen that, relative to Comparative Example 10, during the extrusion process, when the effective content of PTFE is consistent, the liquid silicone-coated PTFE emulsion anti-drip agent prepared by the present invention is added to the PC matrix, and the material strips are smooth during extrusion without outlet expansion and strip breakage.

[0068] Flame retardant test:

[0069] Application Example 2

[0070] Using a twin-screw extruder (melting section 260°C), the anti-drip agents prepared in Examples 1-5 and Comparative Examples 1-8 were blended in an amount of 0.4wt% with PC (melt index: 10g / 10min) and perfluorobutane sulfonate, stretched into strips, and air-cooled and pelletized. The products were respectively recorded as A1, A2, A3, A4, A5, D1, D2, D3, D4, D5, D6, D7, and D8.

[0071] The anti-drip agent of comparative example 9 was blended with PC (melt index: 10 g / 10 min) and perfluorobutane sulfonate at 0.60 wt% and 1.0 wt% respectively using a twin-screw extruder (melting section 260° C.), stretched into strips, and air-cooled and pelletized. The products were recorded as D9 and D10 respectively.

[0072] The anti-drip agent of comparative example 10 was blended with PC (melt index: 10 g / 10 min) and perfluorobutane sulfonate at 0.32% and 0.6 wt% respectively using a twin-screw extruder (melting section 260° C.), stretched into strips, and pelletized with air cooling. The products were recorded as D11 and D12 respectively.

[0073] The dosage of each component in the product prepared in Example 2 is shown in Table 2. The anti-drip performance and flame retardant performance of the product are tested by vertical combustion using a UL94 horizontal vertical combustion instrument. The results are shown in Table 3.

[0074] Table 2

[0075]

[0076]

[0077] Table 3

[0078] Anti-drip effect 1.6mm flame retardant grade A1 No dripping V0 A2 No dripping V0 A3 No dripping V0 A4 No dripping V0 A5 No dripping V0 D1 Dripping V2 D2 Dripping V2 D3 Dripping V2 D4 Dripping V2 D5 Dripping V2 D6 Dripping V2 D7 Dripping V2 D8 Dripping V2 D9 Dripping V2 D10 No dripping V0 D11 Dripping V2 D12 No dripping V0

[0079] It can be seen from Table 2 and Table 3 that, compared with the comparative example, the present invention uniformly mixes a certain amount of liquid silicone with an emulsifier and a PTFE emulsion under certain conditions, and the obtained liquid silicone-coated PTFE emulsion anti-drip agent has better dispersibility in the matrix, and when the effective content of PTFE is 0.16wt%, the anti-drip effect is good, and the flame retardant effect of V0 level is achieved. Moreover, the liquid silicone-coated PTFE emulsion anti-drip agent provided by the present invention eliminates the phenomenon of broken strips and outlet expansion during the extrusion process.

[0080] According to the performance comparison between products D1-D8 and A1, it can be seen that during coating, the type of emulsifier and the amount of emulsifier added, the type of silicone and the amount of silicone added, and the dripping speed of silicone will all affect the coating effect, thereby affecting the performance of the anti-drip agent.

[0081] According to the performance comparison between products D9-D12 and A1, it can be seen that the anti-drip agent of the present invention has a better effect when the anti-drip component polytetrafluoroethylene is added in the same amount.

[0082] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a silicone-coated PTFE emulsion anti-drip agent, characterized in that: The following steps are involved: The PTFE emulsion and the emulsifier are mixed and stirred evenly, and organic silicon is added under high-speed stirring to obtain the anti-drip agent; the added amount of organic silicon accounts for 30-40% of the total mass of the anti-drip agent, and the amount of the emulsifier accounts for 1-3% of the total mass of the anti-drip agent.

2. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 1, characterized in that: The solid content of the PTFE emulsion is 50-70%.

3. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 1, characterized in that: The emulsifier is one of isomeric tridecyl alcohol polyoxyethylene ether 1305 and isomeric tridecyl alcohol polyoxyethylene ether 1308, or a mixture of the two.

4. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 1, characterized in that: The organosilicon is a mixture of one or more of methyl silicone oil, phenyl silicone oil, organosilicon resin FCA-117, organosilicon resin DC8008, and organosilicon resin KR-2710.

5. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 4, characterized in that: The viscosity of the methyl silicone oil is 1000 mPa·s; the viscosity of the phenyl silicone oil is 500 mPa·s.

6. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 1, characterized in that: The added amount of the emulsifier is 1-2% of the total mass of the anti-drip agent.

7. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 1, characterized in that: The stirring speed of the high-speed stirring is 400-600r / min.

8. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 1, characterized in that: The dropping speed of the silicone is 4-6 g / min.

9. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 1, characterized in that: After the addition of the organosilicon is completed, continue stirring for 10-20 minutes.

10. The method for preparing a silicone-coated PTFE emulsion anti-drip agent according to claim 1, characterized in that: The temperature when the organosilicon is added dropwise is 35-45°C.

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