CN111072838A - Polyvinylidene fluoride copolymer dispersion liquid with high-solid content and alternating structure and preparation method thereof - Google Patents
Polyvinylidene fluoride copolymer dispersion liquid with high-solid content and alternating structure and preparation method thereof Download PDFInfo
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- CN111072838A CN111072838A CN201911414538.6A CN201911414538A CN111072838A CN 111072838 A CN111072838 A CN 111072838A CN 201911414538 A CN201911414538 A CN 201911414538A CN 111072838 A CN111072838 A CN 111072838A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
- C08F214/18—Monomers containing fluorine
- C08F214/22—Vinylidene fluoride
- C08F214/225—Vinylidene fluoride with non-fluorinated comonomers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/12—Polymerisation in non-solvents
- C08F2/16—Aqueous medium
- C08F2/22—Emulsion polymerisation
- C08F2/24—Emulsion polymerisation with the aid of emulsifying agents
- C08F2/26—Emulsion polymerisation with the aid of emulsifying agents anionic
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
- C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
- C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C09D127/16—Homopolymers or copolymers of vinylidene fluoride
Abstract
The invention discloses a high-solid content alternating structure polyvinylidene fluoride copolymer dispersion liquid and a preparation method thereof, belonging to the technical field of polyvinylidene fluoride dispersion liquid. The technical scheme is as follows: the preparation method comprises the steps of preparing acrylic acid pre-emulsion by using liquid phase monomers such as acrylic acid monomers and functional monomers, and preparing high-solid content alternating structure polyvinylidene fluoride copolymer dispersion by using vinylidene fluoride and the pre-emulsion. The preparation method of the invention enables the acrylic resin and the polyvinylidene fluoride molecules to be fused at the molecular level and to form an alternate structure, thereby obtaining the polyvinylidene fluoride copolymer dispersion with more excellent performance.
Description
Technical Field
The invention relates to the technical field of polyvinylidene fluoride dispersion liquid, in particular to polyvinylidene fluoride copolymer dispersion liquid with a high solid content and an alternate structure and a preparation method thereof.
Background
Since the commercial production of polyvinylidene fluoride (PVDF) in 1965, PVDF is the most weatherable coating resin recognized by the building industry and can be used outdoors for more than 20 years. Its excellent durability stems from one of the strongest known carbon-fluorine bonds (C-F), the currently best PVDF coating has a 7:3 blend ratio of PVDF to acrylic.
In recent years, with the increasing demand for environmental protection of materials, it is urgent to reduce the content of Volatile Organic Compounds (VOC) in a coating material. On one hand, the traditional solvent-based PVDF coating needs a large amount of solvent when in use, and on the other hand, the traditional solvent-based PVDF coating needs high-temperature baking, can only be used for metal substrates, and needs a large amount of energy consumption in the film forming process. The low temperature, water-based and substrate diversification of PVDF coating become the requirements of the development of times.
In order to prepare the water-soluble polyvinylidene fluoride dispersion, researchers at home and abroad make a lot of improvement work on the production and polymerization of PVDF. The Achima company has provided aqueous polyvinylidene fluoride dispersion, the preparation method of this dispersion is to get PVDF homopolymerization or copolymerization latex first, add thermoplastic or thermosetting acrylic acid on this basis and carry on "acrylic acid seed latex polymerization", reach PVDF resin and molecular level of acrylic resin to fuse finally, make the product property get the optimization. There are related documents reporting that the PVDF aqueous paint is prepared by directly concentrating about 17 wt% of PVDF aqueous emulsion into about 30 wt% of concentrated solution and then mixing with acrylic resin solution, and the general process is as follows: adding a large amount of non-ionic emulsifier into the polymer emulsion at high temperature, then cooling to the cloud point temperature of the non-ionic emulsifier and standing for 10-30min to obtain an upper transparent aqueous solution layer and a lower emulsion concentrated layer, so the process has the defects that the PVDF aqueous concentrated solution is unstable and easy to disperse, the surfactant content of the concentrated solution is high, and then the concentrated solution is mixed with the acrylic resin solution to obtain the PVDF aqueous coating, and the emulsion is unstable due to later physical blending.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a high-solid content alternating structure polyvinylidene fluoride copolymer dispersion and a preparation method thereof, wherein a compounding technology of a fluorine-containing surfactant and a fluorine-free surfactant is adopted, a water-soluble monomer and an acrylic monomer are introduced, emulsion polymerization is adopted, and the mass ratio of acrylic resin to polyvinylidene fluoride resin in the prepared high-solid content alternating structure polyvinylidene fluoride copolymer dispersion is 30-50:70-50, the solid content is up to 40-45 wt%, so that the requirement of a water-based PVDF coating is completely met.
The technical scheme of the invention is as follows:
in one aspect, the invention provides a preparation method of a polyvinylidene fluoride copolymer dispersion liquid with a high solid content alternating structure, which comprises the following steps:
s1: preparation of pre-emulsion: adding 1.0L-4.5L of deionized water, 100g-500g of acrylic hard monomer, 100g-500g of acrylic soft monomer, 10g-40g of functional monomer and 10-40g of 20 wt% of composite dispersant into a pre-emulsification kettle, and stirring and emulsifying for 15-20min for later use;
s2: preparation of high-solid content alternating structure polyvinylidene fluoride copolymer dispersion liquid
S21: adding 2.5L-6L of deionized water, 0.3-1.5L of pre-emulsion prepared from LS1, 5-15g of paraffin and 40-80g of 20 wt% composite dispersant into a high-pressure reaction kettle, and vacuumizing to remove oxygen until the oxygen content is less than or equal to 20 ppm;
s22: introducing vinylidene fluoride monomer to the kettle pressure of 2.0-5.0MPa, stirring, adding an initiator solution and a molecular weight regulator, starting a polymerization reaction, keeping the temperature at 80-115 ℃ and the kettle pressure at 2.0-5.0MPa, reacting for 10-20min, then respectively replenishing the initiator solution, the pre-emulsion and the molecular weight regulator at a constant speed, and finishing the addition within 2.5-3.0 h;
s23: keeping the temperature and the pressure of the kettle constant, and stopping the reaction after reacting for 30-40 min;
s24: and recovering the unreacted monomer to obtain the polyvinylidene fluoride copolymer dispersion.
Liquid phase monomers such as acrylic monomers, functional monomers and the like of S1 are firstly pre-emulsified and then added into a polymerization kettle together with vinylidene fluoride gas phase monomers at a constant speed for polymerization, so that the proportion of various monomer contents in the aqueous solution of the polymerization kettle is ensured, and a preset target product is achieved.
Preferably, in S1, the acrylic hard monomer is methyl methacrylate, ethyl methacrylate, styrene and/or acrylonitrile.
Preferably, the acrylic hard monomer is methyl methacrylate.
Preferably, in S1, the acrylic soft monomer is ethyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate and/or lauryl methacrylate.
Preferably, the soft acrylic monomer is n-butyl acrylate.
Preferably, in S1, the functional monomer is acrylamide, methylolacrylamide, diacetone acrylamide and glycidyl methacrylate and/or dimethylaminoethyl acrylate.
Preferably, in S1, the functional monomer is methylolacrylamide.
Preferably, in S1, the functional monomer is used in an amount of 1 to 6 wt% based on the total amount of acrylic acid monomers.
Preferably, in S1 and S21, the composite dispersant is prepared by compounding a fluorine-containing surfactant and a non-fluorine-containing surfactant in a mass ratio of 1: 0.1-5.0.
Preferably, the mass ratio of the fluorine-containing surfactant to the non-fluorine-containing surfactant is 1: 0.3-3.0.
Preferably, the amount of the composite dispersant used in S1 and S21 is 0.01-5.0 wt% of the total amount of deionized water used in S1 and S21.
Preferably, the fluorine-containing surfactant is a fluorine-containing ester emulsifier, a fluorine-containing ether emulsifier or a fluorine-containing sulfonic acid emulsifier.
Preferably, the fluorine-containing surfactant is a fluorine-containing ether emulsifier.
Preferably, the fluorine-free surfactant is a carboxylate surfactant, a sulfate surfactant, a sulfonate surfactant and/or a phosphate surfactant.
Preferably, the sulfate-type surfactant is an anionic surfactant.
Preferably, the anionic surfactant is sodium lauryl sulfate, sodium lauryl sulfate or sodium lauryl carbonate.
The preparation method of the composite dispersant in S1 is as follows: firstly, deionized water is used for respectively preparing a fluorine-containing surfactant solution and a non-fluorine-containing surfactant solution with the concentration of 10-30 wt%, and then the fluorine-containing surfactant and the non-fluorine-containing surfactant composite dispersing agent with different proportions are prepared according to requirements.
Preferably, in S22, the initiator is ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl hydroperoxide and/or azobisisobutyronitrile organic initiator.
Preferably, the initiator is an organic initiator of azobisisobutyronitrile type.
Preferably, the amount of the initiator is 0.1-10.0 wt% of the total amount of the vinylidene fluoride monomer.
Preferably, the mass concentration of the initiator is 5-15%.
Preferably, the mass concentration of the initiator is 8% -12%.
Preferably, in S22, the molecular weight regulator is ethyl propionate, butyl propionate, ethyl acetate, butyl acetate and/or methyl acetate.
Preferably, the molecular weight regulator is ethyl acetate.
Preferably, the amount of the molecular weight regulator is 0.1-10.0 wt% of the total amount of the vinylidene fluoride monomer.
On the other hand, the invention also provides the polyvinylidene fluoride copolymer dispersion liquid with the high-solid content alternating structure prepared by the preparation method.
The invention has the beneficial effects that:
1. the invention adopts the compounding technology of the fluorine-containing surfactant and the conventional surfactant, introduces the water-soluble monomer to increase the water solubility of the monomer, and adopts the alternating emulsion polymerization process on the polymerization process, so that the acrylic resin and the polyvinylidene fluoride molecules are fused at the molecular level and form an alternating structure, thereby obtaining the polyvinylidene fluoride copolymer dispersion with less dispersant content and more excellent emulsion stability.
2. The polyvinylidene fluoride copolymer dispersion liquid prepared by the preparation method has high solid content, and meanwhile, the acrylic resin and the polyvinylidene fluoride in the preparation method form an alternate structure on the molecular level, and no part where the acrylic resin is concentrated and continuously exists, so that the weather resistance is good compared with the performance of the blending polyvinylidene fluoride resin under the same condition.
3. In the polyvinylidene fluoride copolymer prepared by the invention, the mass ratio of the polyvinylidene fluoride resin to the acrylic resin is 50-70: 30-50, when the mass ratio of the polyvinylidene fluoride to the acrylic acid is 50:50, the performance of the polyvinylidene fluoride-acrylic acid composite paint film reaches the performance of the traditional solvent-type PVDF paint film, so that the content of PVDF resin is reduced, the cost is reduced, and when the mass ratio of the polyvinylidene fluoride to the acrylic acid is 70:30, the performance of the polyvinylidene fluoride-acrylic acid composite paint film exceeds the performance of the traditional solvent-type PVDF paint film, and the service time is longer; in addition, the solid content of the polyvinylidene fluoride copolymer dispersion liquid prepared by the invention is up to 40-45 wt%, and the emulsion stability is good.
Detailed Description
In order to make those skilled in the art better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1 preparation of an aqueous polyvinylidene fluoride Dispersion Using the method of the invention
The preparation method of the high-solid content alternating structure polyvinylidene fluoride copolymer dispersion liquid of the embodiment comprises the following steps:
s1: preparation of pre-emulsion: adding 2.5L of deionized water, 40g of 20 wt% of fluoropolyether carboxylate surfactant and 20 wt% of sodium dodecyl sulfate solution which are uniformly mixed in a mass ratio of 1:1 into a 10L pre-emulsification kettle, uniformly stirring for 5min to uniformly mix, adding 500g of methyl methacrylate, 500g of n-butyl acrylate and 40g of acrylamide, and stirring and emulsifying for 15min for later use;
s2: preparation of aqueous polyvinylidene fluoride resin dispersion
S21: adding 4L of deionized water, 0.5L S1 prepared acrylic acid pre-emulsion, 10g of solid paraffin, 60g of 20 wt% fluorine-containing polyether carboxylate solution and 20 wt% sodium dodecyl sulfate solution which are uniformly mixed in a mass ratio of 1:1 into a cleaned 10L high-pressure polymerization kettle, and vacuumizing to remove oxygen until the oxygen content is less than or equal to 20 ppm;
s22: heating a polymerization kettle, simultaneously adding vinylidene fluoride monomer to increase the pressure of the polymerization kettle until the temperature in the polymerization kettle reaches 85 ℃ and the pressure reaches 3.5Mpa, rapidly pumping 30g of 10 wt% azobisisobutyronitrile initiator solution and 5g of molecular weight regulator ethyl acetate by using a metering pump, starting a polymerization reaction, keeping the temperature at 85 ℃, and after reacting for 15 minutes, respectively pumping 60g of 10 wt% azobisisobutyronitrile initiator solution, 2L pre-emulsion and 20g of molecular weight regulator ethyl acetate at constant speed by using the metering pump, wherein the pumping time is 2.5 hours;
s23: in the polymerization reaction process, the kettle pressure is kept constant by replenishing vinylidene fluoride monomer, and then the reaction is carried out for 30-40min to ensure that the feeding amount of the vinylidene fluoride reaches 1560g, namely the reaction is stopped when the ratio of the feeding amount of the vinylidene fluoride to the feeding amount of the acrylic monomer is 60: 40;
s24: recovering unreacted monomer, and filtering to obtain polyvinylidene fluoride copolymer dispersion.
Example 2
The preparation method of the high-solid content alternating structure polyvinylidene fluoride copolymer dispersion liquid of the embodiment comprises the following steps:
s1: preparation of pre-emulsion: adding 1L of deionized water, 10g of 20 wt% of fluorine-containing alkyl sulfonate FS-10 solution and 20 wt% of sodium dodecyl sulfate solution which are uniformly mixed in a mass ratio of 1:1 into a 10L pre-emulsification kettle, uniformly stirring for 5min to uniformly mix, adding 320g of ethyl methacrylate, 320g of ethyl acrylate and 20g of hydroxymethyl acrylamide, and stirring and emulsifying for 20min for later use;
s2: preparation of aqueous polyvinylidene fluoride resin dispersion
S21: adding 2.5L of deionized water, 1.5L of 1.5L S1 prepared acrylic acid pre-emulsion, 15g of solid paraffin, 40g of 20 wt% of fluorine-containing alkyl sulfonate FS-10 solution and 20 wt% of sodium dodecyl sulfate solution which are uniformly mixed in a mass ratio of 1:1 into a cleaned 10L high-pressure polymerization kettle, and vacuumizing to remove oxygen until the oxygen content is less than or equal to 20ppm, so that the product is qualified;
s22: heating a polymerization kettle, simultaneously adding vinylidene fluoride monomer to increase the pressure of the polymerization kettle until the temperature in the polymerization kettle reaches 115 ℃ and the pressure reaches 5Mpa, rapidly pumping 560g of 10 wt% tert-butyl hydroperoxide initiator solution and 28g of molecular weight regulator ethyl propionate by using a metering pump, starting a polymerization reaction, keeping the temperature at 115 ℃, and after 20 minutes of reaction, respectively pumping 1000g of 10 wt% tert-butyl hydroperoxide initiator solution, 2L of pre-emulsion and 50g of molecular weight regulator ethyl propionate at a constant speed by using the metering pump, wherein the pumping time is 3 hours;
s23: in the polymerization reaction process, the kettle pressure is kept constant by replenishing vinylidene fluoride monomer, and then the reaction is carried out for 30-40min to ensure that the feeding amount of the vinylidene fluoride reaches 1560g, namely the reaction is stopped when the ratio of the feeding amount of the vinylidene fluoride to the feeding amount of the acrylic monomer is 70: 30;
s24: recovering unreacted monomer, and filtering to obtain polyvinylidene fluoride copolymer dispersion.
Example 3
The preparation method of the high-solid content alternating structure polyvinylidene fluoride copolymer dispersion liquid of the embodiment comprises the following steps:
s1: preparation of pre-emulsion: adding 4.5L of deionized water and 40g of 20 wt% fluorine-containing alkyl carbonate surfactant solution and 20 wt% sodium dodecyl carbonate solution which are uniformly mixed in a mass ratio of 1:1 into a 10L pre-emulsification kettle, uniformly stirring for 5min to uniformly mix, adding 100g of styrene, 100g of lauryl acrylate and 10g of diacetone acrylamide, and stirring and emulsifying for 20min for later use;
s2: preparation of aqueous polyvinylidene fluoride resin dispersion
S21: adding 6L of deionized water, 0.3L S1 prepared acrylic acid pre-emulsion, 5g of solid paraffin, 80g of 20 wt% fluorine-containing alkyl carbonate surfactant solution and 20 wt% sodium dodecyl carbonate solution which are uniformly mixed in a mass ratio of 1:1 into a cleaned 10L high-pressure polymerization kettle, and vacuumizing to remove oxygen until the oxygen content is less than or equal to 20ppm, so that the product is qualified;
s22: heating a polymerization kettle, adding vinylidene fluoride monomer to increase the pressure of the polymerization kettle until the temperature in the polymerization kettle reaches 80 ℃ and the pressure reaches 2Mpa, rapidly pumping 35g of 10 wt% ammonium persulfate initiator solution and 5g of molecular weight regulator butyl propionate by using a metering pump, starting a polymerization reaction, keeping the temperature at 80 ℃, after reacting for 10 minutes, respectively pumping 70g of 10 wt% ammonium persulfate initiator solution, 2L of pre-emulsion and 16g of molecular weight regulator butyl propionate at a constant speed by using the metering pump, and pumping for 3 hours;
s23: in the polymerization reaction process, the kettle pressure is kept constant by replenishing vinylidene fluoride monomer, and then the reaction is carried out for 30-40min to ensure that the feeding amount of the vinylidene fluoride reaches 210g, namely the reaction is stopped when the feeding amount of the vinylidene fluoride and the feeding amount of the acrylic monomer are in a ratio of 50: 50;
s24: recovering unreacted monomer, and filtering to obtain polyvinylidene fluoride copolymer dispersion.
Comparative example 1 preparation of polyvinylidene fluoride and acrylic acid blend emulsion Using blending method
The preparation method of comparative example 1 includes the following steps:
s1: preparation of polyvinylidene fluoride emulsion
S11: to a clean 10L polymerizer, 6.5L deionized water, 10g paraffin wax and 60g of 20 wt% 1:1, vacuumizing and deoxidizing the solution of perfluoropolyether carboxylate and sodium dodecyl sulfate until the oxygen content is less than or equal to 20 ppm;
s12: heating a polymerization kettle, simultaneously adding vinylidene fluoride monomer to increase the pressure of the polymerization kettle until the temperature in the polymerization kettle reaches 85 ℃ and the pressure reaches 3.5Mpa, rapidly pumping 20g of 10% azobisisobutyronitrile initiator solution and 4g of molecular weight regulator ethyl acetate by using a metering pump, starting a polymerization reaction, keeping the temperature at 85 ℃, after reacting for 15 minutes, respectively pumping 40g of 10 wt% azobisisobutyronitrile initiator solution and 15g of molecular weight regulator ethyl acetate at a constant speed by using the metering pump, and pumping for 2.5 hours;
s13: in the polymerization reaction process, the reaction kettle pressure is kept constant by replenishing vinylidene fluoride monomer, then the reaction is stopped when the feeding amount of the vinylidene fluoride reaches 1300g by reacting for 30-40min, the monomer is recovered, and the polyvinylidene fluoride emulsion is obtained by filtering.
Preparation of S2 acrylic emulsion
S21: preparation of pre-emulsion: adding 6.5L of deionized water, 40g of 1:1, uniformly mixed 20 wt% of perfluoropolyether carboxylate solution and 20 wt% of sodium dodecyl sulfate solution into a 10L pre-emulsification kettle, uniformly stirring for 5min to uniformly mix, adding 500g of methyl methacrylate, 500g of n-butyl acrylate and 40g of acrylamide, and stirring and emulsifying for 15min for later use;
s22: synthesis of water-soluble acrylic emulsion: adding 1/2S 21 prepared pre-emulsion and 10g of 10 wt% azobisisobutyronitrile initiator solution into a cleaned 10L polymerization kettle, heating to 85 ℃, keeping the temperature constant for 15min to initiate reaction, then adding 20g of 10 wt% azobisisobutyronitrile initiator solution and the rest of S21 prepared pre-emulsion into the reaction kettle at constant speed, finishing the addition for 2.5h, keeping the constant temperature of 85 ℃ for reaction for 30min, and stopping the reaction to obtain the water-soluble acrylic emulsion.
S3: preparation of polyvinylidene fluoride and acrylic acid blended emulsion
Mixing the polyvinylidene fluoride emulsion prepared in the step S1 with the water-soluble acrylic emulsion prepared in the step S2 according to the mass ratio of 70:30 to prepare the polyvinylidene fluoride-acrylic acid blended emulsion.
Comparative example 2 commercially available solvent-based PVDF varnish (YJ 2443(SA) -CLEAR G, a New Material Ltd, Korea, Jiangsu Koppel).
The results of comparing the properties of the polyvinylidene fluoride copolymer dispersions prepared in examples 1-3 with the polyvinylidene fluoride and acrylic acid blend emulsion of comparative example 1 are shown in table 1:
TABLE 1
| Mechanical stability | Storage stability (6 months) | Solid content wt% | |
| Example 1 | Stabilization | Stabilization | 40 |
| Example 2 | Stabilization | Stabilization | 45 |
| Example 3 | Stabilization | Stabilization | 45 |
| Comparative example 1 | Unstable and easily delaminated | Unstable and easily delaminated | 18 |
As can be seen from table 1, the emulsions of examples 1, 2 and 3 are excellent in mechanical stability and storage stability, and can be stored for about 6 months. Meanwhile, the solid content of the emulsion in the embodiment 1, the embodiment 2 and the embodiment 3 is larger and can reach more than 40 wt%. The blending emulsion of comparative example 1 has poor mechanical stability and is easy to delaminate, and the solid content is only 18 wt%, which is far lower than that of the polyvinylidene fluoride copolymer dispersion prepared by the invention.
Furthermore, the results of comparing the properties of the paint films prepared from the emulsions of examples 1 to 3 and comparative examples 1 to 2 are shown in Table 2:
TABLE 2
As can be seen from Table 2, the paint film obtained by blending the aqueous PVDF emulsion and the acrylic emulsion in the comparative example 1 has low gloss, and the boiling water adhesion and the acid and alkali resistance do not pass; the acrylic resins of examples 1, 2, and 3 are molecularly bonded to the PVDF resin, and therefore have higher gloss, as compared to the solvent-based PVDF paint film performance of comparative example 2 in examples 1, 2, and 3. And except that the glossiness of the paint film product of the embodiment 3 is better than that of the paint film product of the comparative example 2, the other performances are equivalent to those of the comparative example 2, but the mass ratio of the polyvinylidene fluoride to the acrylic acid of the embodiment 3 is 50:50, and the mass ratio of the polyvinylidene fluoride to the acrylic acid of the comparative example 2 is 70:30, which shows that under the premise of equivalent performances, the PVDF resin content is reduced, and the cost is reduced. When the mass ratio of the polyvinylidene fluoride to the acrylic acid in the embodiment 2 reaches 70:30, the paint film has better weather resistance and better performance.
Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. The preparation method of the polyvinylidene fluoride copolymer dispersion liquid with the high solid content and the alternate structure is characterized by comprising the following steps:
s1: preparation of pre-emulsion: adding 1.0L-4.5L of deionized water, 100g-500g of acrylic hard monomer, 100g-500g of acrylic soft monomer, 10g-40g of functional monomer and 10-40g of 20 wt% of composite dispersant into a pre-emulsification kettle, and stirring and emulsifying for 15-20min for later use;
s2: preparation of high-solid content alternating structure polyvinylidene fluoride copolymer dispersion liquid
S21: adding 2.5L-6L of deionized water, 0.3-1.5L of pre-emulsion prepared from LS1, 5-15g of paraffin and 40-80g of 20 wt% composite dispersant into a high-pressure reaction kettle, and vacuumizing to remove oxygen until the oxygen content is less than or equal to 20 ppm;
s22: introducing vinylidene fluoride monomer to the kettle pressure of 2.0-5.0MPa, stirring, adding an initiator solution and a molecular weight regulator, starting a polymerization reaction, keeping the temperature at 80-115 ℃ and the kettle pressure at 2.0-5.0MPa, reacting for 10-20min, then respectively replenishing the initiator solution, the pre-emulsion and the molecular weight regulator at a constant speed, and finishing the addition within 2.5-3.0 h;
s23: keeping the temperature and the pressure of the kettle constant, and stopping the reaction after reacting for 30-40 min;
s24: and recovering the unreacted monomer to obtain the polyvinylidene fluoride copolymer dispersion.
2. The method for preparing the high-solid content alternating structure polyvinylidene fluoride copolymer dispersion of claim 1, wherein in S1, the acrylic hard monomer is methyl methacrylate, ethyl methacrylate, styrene and/or acrylonitrile; preferably, the acrylic hard monomer is methyl methacrylate.
3. The method of preparing the high-solid alternating structure polyvinylidene fluoride copolymer dispersion of claim 1, wherein in S1, the acrylic soft monomer is ethyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate and/or lauryl methacrylate; preferably, the soft acrylic monomer is n-butyl acrylate.
4. The method of claim 1, wherein in S1, the functional monomer is acrylamide, methylolacrylamide, diacetone acrylamide, glycidyl methacrylate and/or dimethylaminoethyl acrylate; preferably, in S1, the functional monomer is methylol acrylamide; preferably, in S1, the functional monomer is used in an amount of 1 to 6 wt% based on the total amount of acrylic acid monomers.
5. The method for preparing the high-solid content alternating structure polyvinylidene fluoride copolymer dispersion liquid according to claim 1, wherein in S1 and S21, the composite dispersing agent is prepared by compounding a fluorine-containing surfactant and a non-fluorine-containing surfactant in a mass ratio of 1: 0.1-5.0; preferably, the mass ratio of the fluorine-containing surfactant to the non-fluorine-containing surfactant is 1: 0.3-3.0; preferably, the amount of the composite dispersant used in S1 and S21 is 0.01-5.0 wt% of the total amount of deionized water used in S1 and S21.
6. The method for preparing the polyvinylidene fluoride copolymer dispersion liquid with the high solid content and the alternating structure according to claim 5, wherein the fluorine-containing surfactant is a fluorine-containing ester emulsifier, a fluorine-containing ether emulsifier, or a fluorine-containing sulfonic acid emulsifier; preferably, the fluorine-containing surfactant is a fluorine-containing ether emulsifier.
7. The method for producing a high-solid content alternating structure polyvinylidene fluoride copolymer dispersion according to claim 5, wherein the fluorine-free surfactant is a carboxylate-based surfactant, a sulfate-based surfactant, a sulfonate-based surfactant and/or a phosphate-based surfactant; preferably, the sulfate surfactant is an anionic surfactant; preferably, the anionic surfactant is sodium lauryl sulfate, sodium lauryl sulfate or sodium lauryl carbonate.
8. The method for preparing the polyvinylidene fluoride copolymer dispersion liquid with the high solid content alternating structure according to claim 1, wherein in S22, the initiator is an organic initiator of ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl hydroperoxide and/or azobisisobutyronitrile; preferably, the initiator is an organic initiator of azobisisobutyronitrile type; preferably, the amount of the initiator is 0.1-10.0 wt% of the total amount of the vinylidene fluoride monomer; preferably, the mass concentration of the initiator is 5% -15%; preferably, the mass concentration of the initiator is 8% -12%.
9. The method according to claim 1, wherein in S22, the molecular weight modifier is ethyl propionate, butyl propionate, ethyl acetate, butyl acetate and/or methyl acetate; preferably, the molecular weight regulator is ethyl acetate; preferably, the amount of the molecular weight regulator is 0.1-10.0 wt% of the total amount of the vinylidene fluoride monomer.
10. The polyvinylidene fluoride copolymer dispersion with high solid content alternating structure prepared by the method for preparing polyvinylidene fluoride copolymer dispersion with high solid content alternating structure according to claims 1-9.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111518235A (en) * | 2020-06-29 | 2020-08-11 | 天津城建大学 | Water-based vinylidene chloride copolymer resin and preparation method thereof |
| CN115594789A (en) * | 2022-11-01 | 2023-01-13 | 万华化学集团股份有限公司（Cn） | Method for preparing polyvinylidene fluoride resin by copolymerization of acrylic acid |
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| CN105273121A (en) * | 2015-11-25 | 2016-01-27 | 浙江巨化股份有限公司电化厂 | Preparation method of fluorine-containing polyvinylidene chloride emulsion for coating |
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| GB1388479A (en) * | 1971-02-19 | 1975-03-26 | Pechiney Ugine Kuhlmann | Process for the preparation of and dispersion of positively charged particles of polytetrafluoethylene |
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| CN111518235A (en) * | 2020-06-29 | 2020-08-11 | 天津城建大学 | Water-based vinylidene chloride copolymer resin and preparation method thereof |
| CN115594789A (en) * | 2022-11-01 | 2023-01-13 | 万华化学集团股份有限公司（Cn） | Method for preparing polyvinylidene fluoride resin by copolymerization of acrylic acid |
| CN115594789B (en) * | 2022-11-01 | 2023-09-19 | 万华化学集团股份有限公司 | Method for preparing polyvinylidene fluoride resin by acrylic acid copolymerization |
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