Water-plastic latex film and preparation method thereof

Abstract

The invention provides a water-plastic latex film and a preparation method thereof, and belongs to the technical field of latex film preparation. According to the invention, a hydrophilic macromolecular RAFT reagent is used for mediating an oil-soluble monomer to carry out RAFT emulsion polymerization to prepare latex particles, and then the latex film with water plasticity is obtained through a coating film forming method. In the preparation process, by controlling the ratio of the hydrophilic macromolecular RAFT reagent to the oil-soluble monomer, it is guaranteed that the latex film has good water plasticity; by controlling the variety and proportion of the oil-soluble monomer, the emulsion is easy to form a film, and the obtained latex film has excellent mechanical properties. The prepared water-plastic latex film can be formed into various complex shapes after water treatment, the range of water used for processing and forming is wide (pH = 0-9.0, 0-40 DEG C), the water treatment time is extremely short (50-90 s), and the water-plastic performance is excellent.

Description

Technical Field

[0001] The invention relates to the technical field of latex film preparation, in particular to a water-plastic latex film and a preparation method thereof. Background Art

[0002] Plastics are widely used in food packaging, household appliances, and transportation due to their advantages such as light weight, easy processing, and low cost, covering almost every aspect of daily life. However, the processing and molding of plastics still faces the following problems: (1) The processing requires the use of large equipment, which relies on frequent operation and maintenance; (2) The processing conditions such as temperature (>200℃), humidity, and pressure are demanding; (3) The energy consumption during the processing is high, which does not conform to the concept of energy conservation and environmental protection. Water-plastic materials refer to materials that can be processed and molded with the help of water. Such materials have broad application prospects in environmentally friendly processing and material recycling. However, the existing preparation methods of water-plastic materials face the problems of large amounts of organic solvents used and complex preparation processes that make them impossible to scale up. The water-plastic conditions face the problems of high water treatment temperature (50℃) and long water treatment time (30min). Therefore, it is urgent to develop methods with better effects.

[0003] Emulsion polymerization technology has the following advantages: (1) Most emulsion polymerizations use water as the reaction medium, and the preparation process is green and environmentally friendly; (2) The emulsion polymerization reaction rate is fast, and high molecular weight polymers can be obtained, thereby significantly improving production efficiency; (3) Emulsion polymerization can be mass-produced and industrialized, and is widely used in the fields of biology, medicine, and chemical industry. Among them, RAFT emulsion polymerization technology can accurately control the reaction activity, does not require small molecule activators, and can prepare latex particles with a single particle size distribution, a clean surface, and no activator residue. However, the water plasticity of the latex film obtained using emulsion polymerization technology is very poor and cannot meet the technical requirements.

[0004] Therefore, how to use emulsion polymerization technology to prepare a water-plastic latex film with good water plasticity, short water treatment time and low water temperature has become a technical problem to be solved urgently in this field. Summary of the invention

[0005] The purpose of the present invention is to provide a water-plastic latex film and a preparation method thereof. The water-plastic latex film provided by the present invention can become soft and plastic after being soaked in water (pH=0-9.0, 0-40°C) for 50s. It has low requirements for water and a short water treatment time. At the same time, it can be formed into various complex shapes and has good water plasticity.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a water-plastic latex film, comprising the following steps:

[0008] (1) mixing a hydrophilic macromolecular RAFT agent solution, an oil-soluble monomer and a solvent, then adding a water-soluble initiator solution to form a mixed solution, and sequentially subjecting the mixed solution to freezing ventilation, ultrasonic treatment and RAFT emulsion polymerization to obtain a RAFT soap-free emulsion; the oil-soluble monomer includes a soft segment monomer; the mass ratio of the hydrophilic macromolecular RAFT agent to the oil-soluble monomer in the mixed solution is 1:(1-5);

[0009] (2) The RAFT soap-free emulsion obtained in step (1) is used to prepare a water-plastic latex film by a coating film-forming method.

[0010] Preferably, the preparation method of the hydrophilic macromolecular RAFT agent in step (1) is: mixing the RAFT agent, initiator, monomer and solvent, dissolving them by ultrasonication, then freezing and ventilating, then performing RAFT solution polymerization reaction, and finally sequentially performing quenching, solvent rotary evaporation, precipitation purification and vacuum drying to obtain the hydrophilic macromolecular RAFT agent.

[0011] Preferably, the RAFT agent is 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid and / or 4-cyanopentanoyl dithiobenzoic acid; the initiator is one or more of azobisisobutyronitrile, azobisisoheptanoonitrile and azobiscyclohexylcarbonitrile; the monomer is one or more of dimethylaminoethyl methacrylate, methacrylic acid, glycidyl methacrylate and oligoethylene glycol methacrylate; the solvent is one or more of 1,4-dioxane, tetrahydrofuran and N,N-dimethylformamide.

[0012] Preferably, the temperature of the RAFT solution polymerization reaction is 60-80° C., and the time of the RAFT solution polymerization reaction is 6-15 h.

[0013] Preferably, in step (1), the water-soluble initiator is 2,2'-azabis(2-imidazoline) dihydrochloride and / or 4,4'-azobis(4-cyanovaleric acid); and the solvent is one or more of ultrapure water, acidic ultrapure water, sodium chloride solution and phosphate buffer solution.

[0014] Preferably, the temperature of the RAFT emulsion polymerization in step (1) is 40 to 60° C., and the time of the RAFT emulsion polymerization is 12 to 20 hours.

[0015] Preferably, the method of freezing and ventilation in step (1) is: first evacuate the air under freezing conditions, then fill with argon gas for ventilation, repeat the evacuation and ventilation operations 3 times, then thaw in room temperature water while filling with argon gas, repeat the evacuation-ventilation-thawing operations 3 to 4 times to complete the freezing and ventilation.

[0016] Preferably, the coating film-forming method in step (2) is to coat the RAFT soap-free emulsion and then sequentially perform drying film-forming and reduced pressure heat treatment to obtain a water-plastic latex film.

[0017] The present invention provides a water-plastic latex film prepared by the preparation method described in the above technical scheme.

[0018] Preferably, the water plastic conditions of the water plastic latex film are soaking in water; the pH of the water is 0 to 9.0; the soaking temperature is 0 to 40° C., and the soaking time is 50 to 90 seconds.

[0019] The present invention provides a method for preparing a water-plastic latex film, comprising the following steps: (1) mixing a hydrophilic macromolecular RAFT agent solution, an oil-soluble monomer and a solvent, then adding a water-soluble initiator solution to form a mixed solution, and sequentially subjecting the mixed solution to freezing ventilation, ultrasonic treatment and RAFT emulsion polymerization to obtain a RAFT soap-free emulsion; the oil-soluble monomer includes a soft segment monomer; the mass ratio of the hydrophilic macromolecular RAFT agent to the oil-soluble monomer in the mixed solution is 1:(1-5); (2) using the RAFT soap-free emulsion obtained in the step (1) to prepare a water-plastic latex film by a coating film-forming method. The present invention uses a hydrophilic macromolecular RAFT agent to mediate an oil-soluble monomer to carry out RAFT emulsion polymerization to prepare a RAFT soap-free emulsion, and then obtains a latex film with excellent water plasticity by a coating film-forming method. During the preparation process, the present invention controls the ratio of hydrophilic macromolecular RAFT agent to oil-soluble monomers, thereby ensuring that the latex film has good water plasticity; by controlling the type and ratio of oil-soluble monomers, the emulsion is easy to form a film while ensuring that the obtained latex film has excellent mechanical properties.

[0020] The preparation method provided by the present invention has the advantages of short process flow, environmental protection, simple operation and low energy consumption, indicating its broad application potential for large-scale industrialization. The results of the embodiment show that the water-plastic latex film prepared by the preparation method provided by the present invention can be formed into various complex shapes after water treatment, the water used for processing and forming has a wide range (pH = 0 ~ 9.0, 0 ~ 40 ° C), the water treatment time is extremely short (50 ~ 90s), and the water plasticity is very excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The photo of the RAFT soap-free emulsion obtained in step (2) of Example 1 and its dynamic light scattering test result;

[0022] Figure 2 This is a physical picture of the water-plastic latex film obtained in step (3) of Example 1;

[0023] Figure 3 This is a real picture of the water-plastic latex film obtained in step (3) of Example 1 when it is subjected to water treatment;

[0024] Figure 4 This is a physical picture of the dyed water-plastic latex film obtained in step (4) of Example 1;

[0025] Figure 5 The dyed water-plastic latex film obtained in step (4) of Example 1 is subjected to water treatment and formed into various shapes;

[0026] Figure 6 The water absorption rate of the water-plastic latex film obtained in step (3) of Example 1 at different temperatures and in different solvents;

[0027] Figure 7 The stress-strain curves of the water-plastic latex film obtained in step (3) of Example 1 before water absorption, after water absorption for 50 seconds, after water absorption for 200 seconds, and after drying;

[0028] Figure 8 This is the AFM phase image of the water-plastic latex film obtained in step (3) of Example 1 before water absorption;

[0029] Fig. 9 This is the AFM phase image of the water-plastic latex film obtained in step (3) of Example 1 after absorbing water;

[0030] Fig.10 The test results of small angle X-ray scattering (SAXS) of the water-plastic latex film obtained in step (3) of Example 1 before and after water absorption;

[0031] Fig.11 The physical pictures of the products prepared in Comparative Examples 1 to 3;

[0032] Fig.12 This is a real picture of the latex film obtained in Comparative Example 4 after being immersed in 0°C acidic ultrapure water for 50 seconds. DETAILED DESCRIPTION

[0033] The present invention provides a method for preparing a water-plastic latex film, comprising the following steps:

[0034] (1) mixing a hydrophilic macromolecular RAFT agent solution, an oil-soluble monomer and a solvent, then adding a water-soluble initiator solution to form a mixed solution, and sequentially subjecting the mixed solution to freezing ventilation, ultrasonic treatment and RAFT emulsion polymerization to obtain a RAFT soap-free emulsion; the oil-soluble monomer includes a soft segment monomer; the mass ratio of the hydrophilic macromolecular RAFT agent to the oil-soluble monomer in the mixed solution is 1:(1-5);

[0035] (2) The RAFT soap-free emulsion obtained in step (1) is used to prepare a water-plastic latex film by a coating film-forming method.

[0036] In the present invention, unless otherwise specified, the present invention has no particular limitation on the specific sources of the raw materials, and commercially available products well known to those skilled in the art may be used.

[0037] The invention mixes a hydrophilic macromolecular RAFT agent solution, an oil-soluble monomer and a solvent, then adds a water-soluble initiator solution to form a mixed solution, and sequentially performs freezing ventilation, ultrasonic treatment and RAFT emulsion polymerization on the mixed solution to obtain a RAFT soap-free emulsion.

[0038] In the present invention, when preparing the RAFT soap-free emulsion, the synthesis route of the hydrophilic macromolecular RAFT agent is as follows:

[0039] In the present invention, the preparation method of the hydrophilic macromolecular RAFT agent is preferably: the RAFT agent, initiator, monomer and solvent are mixed and then ultrasonically dissolved, then frozen and ventilated, followed by RAFT solution polymerization, and finally quenched, solvent rotary evaporation, precipitation purification and vacuum drying are performed in sequence to obtain the hydrophilic macromolecular RAFT agent.

[0040] In the present invention, the RAFT agent is preferably 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid (CDTPA) and / or 4-cyanopentanoyl dithiobenzoic acid (CPADB). The present invention uses a RAFT agent with a higher chain transfer constant to prepare a macromolecular RAFT agent, which can effectively control the molecular weight, so that the obtained macromolecular RAFT agent has a regular structure, a narrow molecular weight distribution, and good hydrophilicity.

[0041] In the present invention, the initiator is preferably one or more of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (ABVN) and azobiscyclohexylcarbonitrile (ACCN). The present invention can improve the efficiency of RAFT solution polymerization by controlling the type of initiator.

[0042] In the present invention, the monomer is preferably one or more of dimethylaminoethyl methacrylate (DMAEMA), methacrylic acid, glycidyl methacrylate and oligoethylene glycol methacrylate. The present invention can obtain hydrophilic macromolecular RAFT agents with different properties by controlling the type of monomers.

[0043] In the present invention, the solvent is preferably one or more of 1,4-dioxane, tetrahydrofuran and N,N-dimethylformamide. The present invention uses the above solvents to fully dissolve the components, thereby providing the required environment for RAFT solution polymerization.

[0044] In the present invention, the molar ratio of the RAFT agent, initiator, monomer and solvent is preferably 1: (0.1-0.5): (150-500): (277-922), more preferably 1: (0.1-0.5): (200-400): (300-800), and further preferably 1: (0.1-0.5): (250-350): (400-700).

[0045] The present invention has no particular limitation on the time of ultrasonic dissolution and the power of ultrasound during ultrasonic dissolution, which can be determined according to the technical common sense of those skilled in the art as long as the RAFT agent, initiator and monomer are fully and evenly dissolved.

[0046] In the present invention, the freezing and ventilation method is preferably: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, then defrost in room temperature water under argon, repeat the evacuation-ventilation-thawing operations 3 to 4 rounds to complete freezing and ventilation. In the present invention, the temperature of the freezing conditions is preferably -250 to -150°C; the evacuation time is preferably 2 to 3 minutes. Through freezing and ventilation, the present invention can replace the air in the mixed solution and the reaction bottle with argon to remove oxygen, thereby facilitating the subsequent RAFT solution polymerization reaction.

[0047] In the present invention, the temperature of the RAFT solution polymerization reaction is preferably 60-80°C; the time of the RAFT solution polymerization reaction is preferably 6-15h. The present invention controls the parameters of the RAFT solution polymerization reaction to ensure that the raw materials react completely and obtain a hydrophilic macromolecular RAFT agent with a target degree of polymerization.

[0048] As an embodiment, the temperature of the RAFT solution polymerization reaction can be 60°C, 65°C, 70°C, 75°C or 80°C; the time of the RAFT solution polymerization reaction can be 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h or 15h.

[0049] In the present invention, the method of quenching is preferably quenching in liquid nitrogen, while ventilating to quench the reaction. In the present invention, the gas introduced during the ventilation is preferably air or oxygen. The present invention can stop the reaction by quenching.

[0050] The present invention has no particular limitation on the specific operation of the solvent rotary evaporation. The solvent can be rotary dried by using the operation well known to those skilled in the art.

[0051] In the present invention, the precipitation purification method is preferably to dissolve in dichloromethane and then precipitate in icy n-hexane three times. The present invention can almost completely remove the original solvent and unreacted monomers through precipitation purification, thereby improving the purity of the hydrophilic macromolecular RAFT agent.

[0052] The present invention has no particular limitation on the specific parameters of the vacuum drying, as long as the hydrophilic macromolecular RAFT agent can be completely dried.

[0053] The hydrophilic macromolecular RAFT agent prepared by the present invention is a light pink solid water-soluble macromolecular RAFT agent.

[0054] In the present invention, when preparing the RAFT soap-free emulsion, the oil-soluble monomer is selected as follows:

[0055] In the present invention, the oil-soluble monomer includes a soft segment monomer; the soft segment monomer is preferably one or more of n-butyl acrylate, n-octyl methacrylate, n-hexyl methacrylate, n-butyl methacrylate, isoprene, 1,3-butadiene, chloroprene and ethylene propylene diene.

[0056] In the present invention, the oil-soluble monomer preferably further includes a hard segment monomer; the hard segment monomer is preferably one or more of methyl methacrylate, styrene and acrylonitrile.

[0057] In the present invention, when the oil-soluble monomers are two types of monomers, namely, hard segment monomers and soft segment monomers, the mass ratio of the hard segment monomers to the soft segment monomers is preferably (0-1): (1-10000), more preferably (0.01-1): (1-8000), further preferably (0.1-1): (1-5000), and further preferably 1: (1.5-500). In the present invention, the presence and amount of the soft segment monomers are ensured so that the RAFT soap-free emulsion has good film-forming properties; by optimizing the relationship between the amounts of the hard segment monomers and the soft segment monomers, the mechanical properties of the latex film can be further improved without affecting the water plasticity of the latex film.

[0058] In the present invention, the mass ratio of the hydrophilic macromolecular RAFT agent to the oil-soluble monomer in the mixed solution is 1:(1-5), preferably 1:(1-4.5), and more preferably 1:(1.2-4).

[0059] In the present invention, when preparing the RAFT soap-free emulsion, the water-soluble initiator is selected as follows:

[0060] In the present invention, the water-soluble initiator is preferably 2,2'-azabis(2-imidazoline) dihydrochloride (VA-044) and / or 4,4'-azobis(4-cyanovaleric acid) (ABCPA).

[0061] In the present invention, when preparing the RAFT soap-free emulsion, the solvent is selected as follows:

[0062] In the present invention, the solvent is preferably one or more of ultrapure water, acidic ultrapure water, sodium chloride solution and phosphate buffer solution. In the present invention, the acidic ultrapure water is preferably a mixture of ultrapure water and HCl aqueous solution; the pH value of the acidic ultrapure water is preferably 1.0 to 3.0. The present invention has no special restrictions on the specific concentration and dosage of the HCl aqueous solution, which can be determined according to the required pH value of the acidic ultrapure water. The present invention has no special restrictions on the specific concentrations of the sodium chloride solution and the phosphate buffer solution, which can be selected according to the technical common sense of those skilled in the art. The present invention avoids the use of organic solvents in the preparation process, and always uses water or aqueous solution as the reaction medium, which has the advantages of low cost, low toxicity and high safety, conforms to the concept of modern environmentally friendly production, effectively reduces production costs, and significantly improves the sustainability of the production process.

[0063] In the present invention, the preparation method of the RAFT soap-free emulsion is: mixing a hydrophilic macromolecular RAFT agent solution, an oil-soluble monomer and a solvent, then adding a water-soluble initiator solution to form a mixed solution, and sequentially subjecting the mixed solution to freezing ventilation, ultrasonic treatment and RAFT emulsion polymerization to obtain the RAFT soap-free emulsion.

[0064] In the present invention, the ratio of the amount of the hydrophilic macromolecular RAFT agent, the water-soluble initiator, the oil-soluble monomer and the solvent in the mixed solution is preferably 1: (0.1-5): (200-2000): (30000-220000), more preferably 1: (0.5-2): (256-1521): (32911-208615), further preferably 1: (0.5-2): (300-1500): (34000-200000), and further preferably 1: (1-1.5): (500-1200): (35000-150000). The present invention can ensure good film-forming properties of the emulsion and excellent mechanical properties of the film by controlling the dosage relationship of each component, while ensuring that the latex film has good water plasticity.

[0065] In the present invention, the method for preparing the hydrophilic macromolecular RAFT agent solution is preferably to dissolve the hydrophilic macromolecular RAFT agent in a solvent and dissolve it uniformly by ultrasonication. In the present invention, the solvent is preferably the same as the solvent used in preparing the RAFT soap-free emulsion.

[0066] In the present invention, the method for preparing the water-soluble initiator solution is preferably to dissolve the water-soluble initiator in a solvent. In the present invention, the solvent is preferably the same as the solvent used in preparing the RAFT soap-free emulsion.

[0067] In the present invention, the freezing and ventilation method is preferably: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, then defrost in room temperature water under argon, repeat the evacuation-ventilation-thawing operations 3 to 4 times to complete freezing and ventilation. In the present invention, the temperature of the freezing conditions is preferably -250 to -150°C; the evacuation time is preferably 2 to 3 minutes. Through freezing and ventilation, the present invention can replace the air in the mixed solution and the reaction bottle with argon to remove oxygen, thereby facilitating the subsequent RAFT emulsion polymerization.

[0068] The present invention has no special limitation on the power of the ultrasonic treatment, which can be determined according to the technical common sense of those skilled in the art. In the present invention, the time of the ultrasonic treatment is preferably 1 to 3 minutes.

[0069] In the present invention, the temperature of the RAFT emulsion polymerization is preferably 40 to 60° C.; the time of the RAFT emulsion polymerization is preferably 12 to 20 hours. The present invention can ensure complete reaction by controlling the parameters of the RAFT emulsion polymerization.

[0070] As an embodiment, the temperature of the RAFT emulsion polymerization can be 40°C, 45°C, 50°C, 55°C or 60°C; the time of the RAFT emulsion polymerization can be 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h or 20h.

[0071] After obtaining the RAFT soap-free emulsion, the present invention uses the RAFT soap-free emulsion to prepare a water-plastic latex film by a coating film-forming method.

[0072] In the present invention, the coating film-forming method is preferably to coat the RAFT soap-free emulsion and then sequentially perform drying film-forming and reduced pressure heat treatment to obtain a water-plastic latex film.

[0073] In the present invention, the coating thickness is preferably 0.1 to 5 mm; the mold used during the coating is preferably a polytetrafluoroethylene mold.

[0074] In the present invention, the drying film forming temperature is preferably 35-45°C; the drying film forming time is preferably 6-8h; and the drying film forming is preferably carried out in an oven. The present invention obtains a film with uniform thickness and smooth surface by controlling the drying film forming temperature and time.

[0075] As an embodiment, the drying film forming temperature may be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C or 45°C; the drying film forming time may be 6h, 7h or 8h.

[0076] In the present invention, the temperature of the reduced pressure heat treatment is preferably 110-125°C; the time of the reduced pressure heat treatment is preferably 11-13 hours; the reduced pressure heat treatment is preferably carried out in a vacuum oven. In the present invention, the vacuum degree of the reduced pressure heat treatment is preferably ≤-0.1MPa. The present invention controls the vacuum degree to ensure that no oxidation reaction occurs on the surface of the film. The present invention can further remove residual monomers and water in the film through reduced pressure heat treatment.

[0077] As an embodiment, the temperature of the reduced pressure heat treatment may be 110°C, 115°C, 120°C or 125°C; the time of the reduced pressure heat treatment may be 11h, 12h or 13h.

[0078] The present invention utilizes a hydrophilic macromolecular RAFT agent to mediate an oil-soluble monomer to carry out RAFT emulsion polymerization to prepare a RAFT soap-free emulsion, and then obtains a latex film with excellent water plasticity by a coating film-forming method. During the preparation process, the present invention controls the ratio of the hydrophilic macromolecular RAFT agent to the oil-soluble monomer, thereby ensuring that the latex film has good water plasticity; and controls the type and ratio of the oil-soluble monomer, so that the emulsion is easy to form a film, and ensures that the obtained latex film has excellent mechanical properties.

[0079] The preparation method provided by the present invention has the advantages of short process flow, environmental protection, simple operation and low energy consumption, indicating its broad application potential in large-scale industrialization.

[0080] The present invention also provides a water-plastic latex film prepared by the preparation method described in the above technical solution.

[0081] In the present invention, the thickness of the water plastic latex film is preferably 0.01 to 1 mm.

[0082] In the present invention, the water plastic latex film is preferably soaked in water; the pH of the water is preferably 0 to 9.0; the soaking temperature is preferably 0 to 40°C; and the soaking time is preferably 50 to 90 seconds. The present invention can make the water plastic latex film soft and plastic by water treatment, and then mold it into various complex shapes, and finally dry it at room temperature to obtain a latex film with a fixed shape.

[0083] As an embodiment, the pH of the water may be 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 or 9.0; the soaking temperature may be 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C or 40°C; the soaking time may be 50s, 55s, 60s, 65s, 70s, 75s, 80s, 85s or 90s.

[0084] In the present invention, when the pH of the water is 7.0, the water is preferably ultrapure water. The present invention has no special limitation on the resistivity of the ultrapure water, which can be selected according to the technical common sense of those skilled in the art.

[0085] In the present invention, when the pH of the water is less than 7.0, the water is preferably acidic ultrapure water; the acidic ultrapure water is preferably a mixture of ultrapure water and HCl aqueous solution. The present invention has no particular limitation on the specific concentration and dosage of the HCl aqueous solution, which can be determined according to the required pH value of the acidic ultrapure water.

[0086] In the present invention, when the pH of the water is greater than 7.0, the water is preferably an alkaline aqueous solution; the alkaline aqueous solution is preferably any one of a phosphate buffer solution, a sodium bicarbonate buffer solution and a sodium hydroxide solution; the alkaline aqueous solution is preferably a mixture of a solute and ultrapure water. The present invention has no special restrictions on the selection and specific dosage of the solute, which can be determined according to the technical common sense of those skilled in the art and the required pH value of the alkaline aqueous solution.

[0087] The water-plastic latex film prepared by the present invention can be processed and formed in water at room temperature, has low temperature requirements for the water used (0-40°C), extremely short water treatment time (50-90s), and the range of water used for its processing and forming is very wide (pH=0-9.0). The process flow is short and the operation is simple, and it has broad application prospects in environmental protection processing, material recycling, etc.

[0088] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0089] Example 1

[0090] A method for preparing a water-plastic latex film comprises the following steps:

[0091] (1) The preparation method of a hydrophilic macromolecular RAFT agent is as follows: 0.0448 g of a RAFT agent, 0.0039 g of an initiator, 7.0798 g of a monomer and 7.238 g of a solvent are mixed and then ultrasonically dissolved, followed by freezing and ventilation, followed by RAFT solution polymerization, and finally quenching in liquid nitrogen while ventilating to quench the reaction, after rotary evaporation of the solvent, dissolving it with dichloromethane and precipitating it in ice-cold n-hexane three times, followed by vacuum drying to obtain a light pink solid hydrophilic macromolecular RAFT agent; the RAFT agent is CPADB; The initiator is AIBN; the monomer is dimethylaminoethyl methacrylate; the solvent is 1,4-dioxane; the freezing and ventilation method is: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, then defrost in room temperature water under argon, repeat the evacuation-ventilation-thawing operations 3 times to complete freezing and ventilation; the temperature of the freezing condition is -196°C; the evacuation time is 3 minutes; the temperature of the RAFT solution polymerization reaction is 70°C, and the RAFT solution polymerization reaction time is 10 hours;

[0092] (2) dissolving a water-soluble initiator in acidic ultrapure water to obtain a water-soluble initiator solution with a concentration of 2 mg / mL, then dissolving 80 mg of the hydrophilic macromolecular RAFT agent obtained in step (1) in 2 mL of acidic ultrapure water and dissolving it uniformly by ultrasonication to obtain a hydrophilic macromolecular RAFT agent solution with a concentration of 40 mg / mL, adding 120 mg of an oil-soluble monomer and 1148 mg of acidic ultrapure water (ensuring that the total amount of solvent is 3543 mg, i.e., the emulsion solid content is 5.5%) to the hydrophilic macromolecular RAFT agent solution, and then adding 0.395 μL (containing 0.79 mg of a water-soluble initiator and 395 mg of a solvent) of the water-soluble initiator solution to form a mixed solution, followed by sequentially performing refrigeration ventilation, ultrasonic treatment for 1 min, and RAFT emulsion polymerization to obtain a RAFT soap-free emulsion; the acidic ultrapure water is made of ultrapure water. The mixture is made of pure water and HCl aqueous solution, and the pH value of the acidic ultrapure water is 1.0; the mass ratio of the hydrophilic macromolecular RAFT agent and the oil-soluble monomer is 1:1.5; the oil-soluble monomer is a hard segment monomer and a soft segment monomer, the hard segment monomer is methyl methacrylate, and the soft segment monomer is n-butyl acrylate, and the mass ratio of the hard segment monomer to the soft segment monomer is 1:1.5; the water-soluble initiator is VA-044; the temperature of the RAFT emulsion polymerization is 40°C, and the time of the RAFT emulsion polymerization is 17h; the freezing and ventilation method is: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, and then thaw in room temperature water under argon filling, repeat the evacuation-ventilation-thawing operations 3 times to complete the freezing and ventilation; the temperature of the freezing conditions is -196°C; the evacuation time is 3min;

[0093] (3) applying 1.4 mL of the RAFT soap-free emulsion obtained in step (2) on a polytetrafluoroethylene mold, and then drying and film-forming and reduced pressure heat treatment are performed in sequence to obtain a water-plastic latex film; the coating thickness is 1.2 mm; the drying film-forming temperature is 40° C., the drying film-forming time is 6 h, and the drying film-forming is performed in an oven; the reduced pressure heat treatment temperature is 120° C., the vacuum degree of the reduced pressure heat treatment is -0.1 MPa, the reduced pressure heat treatment time is 12 h, and the reduced pressure heat treatment is performed in a vacuum oven;

[0094] (4) 1.4 mL of the RAFT soap-free emulsion obtained in step (2) was mixed with 14.9 μL of a 20 mg / mL rhodamine B-acidic ultrapure aqueous solution and then coated on a polytetrafluoroethylene mold, followed by drying and film-forming and reduced pressure heat treatment to obtain a dyed water-plastic latex film; the coating thickness was 1.2 mm; the drying film-forming temperature was 40° C., the drying film-forming time was 6 h, and the drying film-forming was carried out in an oven; the reduced pressure heat treatment temperature was 120° C., the vacuum degree of the reduced pressure heat treatment was -0.1 MPa, the reduced pressure heat treatment time was 12 h, and the reduced pressure heat treatment was carried out in a vacuum oven.

[0095] The water plastic conditions of the water plastic latex film prepared in Example 1 are as follows: after being immersed in ultrapure water at 0°C for 50 seconds, the film becomes soft and plastic and can be formed into various complex shapes. Then, the water plastic latex film with a complex structure can be obtained by drying at room temperature.

[0096] Figure 1 The following is a photograph of the RAFT soap-free emulsion obtained in step (2) of Example 1 and its dynamic light scattering test results. Figure 1 It can be seen that the obtained RAFT soap-free emulsion has a blue light, the particle size of the latex particles in the emulsion is about 63nm, and the polydispersity index (PDI) is 0.010, which is a monodisperse emulsion. The emulsion conversion rate measured by the gravimetric method is more than 95%, indicating that the added monomers have almost all reacted.

[0097] Figure 2 This is a physical picture of the water plastic latex film obtained in step (3) of Example 1. Figure 2 It can be seen that the water-plastic latex film prepared by the present invention has a uniform thickness (0.12 mm), a smooth surface without bubbles, a flat structure, and cannot be molded.

[0098] Figure 3 This is a photo of the water-plastic latex film obtained in step (3) of Example 1 when it is treated with water. Figure 3 It can be seen that the water-plastic latex film prepared by the present invention exhibits a light blue color when subjected to water treatment, and becomes softer and has better plasticity.

[0099] Figure 4 This is a photo of the dyed water-based plastic latex film obtained in step (4) of Example 1. Figure 4 It can be seen that the surface of the dyed water-plastic latex film is smooth and free of bubbles, the thickness is uniform (0.12 mm), and it is tough and cannot be molded, indicating that even after the water-plastic latex film is dyed, its overall structure will not be affected.

[0100] Figure 5 The dyed water-plastic latex film obtained in step (4) of Example 1 is subjected to water treatment and formed into various shapes. Figure 5It can be seen that after the obtained water-plastic latex film is immersed in ultrapure water at 0°C for 50s, the film becomes soft. By molding it and drying it at room temperature, products with fixed shapes such as spiral, gate and circle can be obtained, indicating that the water-plastic latex film provided by the present invention has good water plasticity.

[0101] Figure 6 is the water absorption rate of the water-plastic latex film obtained in step (3) of Example 1 at different temperatures and in different solvents. Figure 6 It can be seen that the water absorption rate of the water-plastic latex film can reach 100-400% within 5-100s, with fast water absorption speed, large water absorption amount and high water absorption efficiency. The range of water used for the processing and molding of the obtained water-plastic latex film is very wide: temperature 0-40℃, pH about 0-9.0.

[0102] Figure 7 The stress-strain curves of the water-plastic latex film obtained in step (3) of Example 1 before water absorption, after water absorption for 50 seconds, after water absorption for 200 seconds, and after drying. Figure 7 It can be calculated that the Young's modulus of the water-plastic latex film before absorbing water is 89.7MPa, the yield strength is 9.54MPa, the breaking strength is 8.1MPa, and the elongation at break is 165%; after absorbing water for 50s and 200s, the Young's modulus is 0.071 and 0.068MPa, the breaking strength is 0.063 and 0.037MPa, and the elongation at break is 113% and 47%; the Young's modulus of the film dried after absorbing water for 50s is 276MPa, the yield strength is 11.9MPa, the breaking strength is 10.1MPa, and the elongation at break is 42%. It can be seen that after the water-plastic latex film absorbs water for 50s and 200s, its Young's modulus and breaking strength are reduced by 1260 times and 1320 times, indicating that the film is strong and tough before absorbing water, and becomes soft and weak after absorbing water, and can be processed and formed. In addition, the Young's modulus and breaking strength of the hydroplastic latex film that was dried after absorbing water for 50 seconds increased, indicating that the mechanical properties of the film formed by water processing were improved.

[0103] Figure 8 This is an atomic force microscope (AFM) phase image of the water-plastic latex film obtained in step (3) of Example 1 before water absorption; Fig. 9 This is the atomic force microscopy (AFM) phase image of the hydroplastic latex film after water absorption. Figure 8 and Fig. 9 In the figure, the darker areas are hydrophilic areas, while the lighter areas are hydrophobic areas, with an average size of about 44.3 nm. Figure 8 and Fig. 9 It can be seen that before absorbing water, the latex film is a bicontinuous phase. After the film is soaked in water, the hydrophilic domain inside it will absorb a large amount of water, and the entry of water makes the film soft. Fig. 9It can be seen that under the same scale, the hydrophobic domain in the membrane after water absorption becomes significantly larger, with a size of 77.9 to 309.5 nm, which is about the fusion of 2 to 8 hydrophobic domains before water absorption, indicating that water promotes the phase separation of hydrophilic domains and hydrophobic domains.

[0104] Fig.10 The following are the test results of small angle X-ray scattering (SAXS) of the water-plastic latex film obtained in step (3) of Example 1 before and after water absorption. Fig.10 It can be seen that the water plastic latex film before absorbing water is at Q = 0.097nm -1 A peak appeared at Q = 0.064 nm. The size of the hydrophobic region was calculated to be 64.7 nm based on 2π / Q. When the hydroplastic latex film absorbed water, its peak moved in the direction of a larger region and exceeded the resolution range of the instrument. -1 A shoulder peak appeared at the membrane surface, and the size of the hydrophobic domain after water absorption was calculated to be 98.125 nm, which was consistent with the AFM characterization results.

[0105] Example 2

[0106] A method for preparing a water-plastic latex film comprises the following steps:

[0107] (1) The preparation method of a hydrophilic macromolecular RAFT agent is as follows: 0.0448 g of a RAFT agent, 0.0039 g of an initiator, 7.0798 g of a monomer and 7.238 g of a solvent are mixed and then ultrasonically dissolved, followed by freezing and ventilation, followed by RAFT solution polymerization, and finally quenching in liquid nitrogen while ventilating to quench the reaction, after rotary evaporation of the solvent, dissolving it with dichloromethane and precipitating it in ice-cold n-hexane three times, followed by vacuum drying to obtain a light pink solid hydrophilic macromolecular RAFT agent; the RAFT agent is CPADB; The initiator is AIBN; the monomer is dimethylaminoethyl methacrylate; the solvent is 1,4-dioxane; the freezing and ventilation method is: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, then defrost in room temperature water under argon, repeat the evacuation-ventilation-thawing operations 3 times to complete freezing and ventilation; the temperature of the freezing condition is -196°C; the evacuation time is 3 minutes; the temperature of the RAFT solution polymerization reaction is 70°C, and the RAFT solution polymerization reaction time is 10 hours;

[0108] (2) dissolving a water-soluble initiator in acidic ultrapure water to obtain a water-soluble initiator solution with a concentration of 2 mg / mL, then dissolving 80 mg of the hydrophilic macromolecular RAFT agent obtained in step (1) in 2 mL of acidic ultrapure water and dissolving it uniformly by ultrasonication to obtain a hydrophilic macromolecular RAFT agent solution with a concentration of 40 mg / mL, adding 160 mg of an oil-soluble monomer and 1746 mg (ensuring that the total amount of solvent is 4141 mg, i.e., the emulsion solid content is 5.5%) of acidic ultrapure water to the hydrophilic macromolecular RAFT agent solution, mixing, then adding 0.395 μL (containing 0.79 mg of a water-soluble initiator and 395 mg of a solvent) of the water-soluble initiator solution to form a mixed solution, followed by sequentially performing refrigeration ventilation, ultrasonic treatment for 1 min, and RAFT emulsion polymerization to obtain a RAFT soap-free emulsion; the acidic ultrapure water is Ultrapure water and HCl aqueous solution are mixed, and the pH value of the acidic ultrapure water is 1.0; the mass ratio of the hydrophilic macromolecular RAFT agent and the oil-soluble monomer is 1:1.5; the oil-soluble monomer is a hard segment monomer and a soft segment monomer, the hard segment monomer is methyl methacrylate, and the soft segment monomer is n-butyl acrylate, and the mass ratio of the hard segment monomer to the soft segment monomer is 1:2; the water-soluble initiator is VA-044; the temperature of the RAFT emulsion polymerization is 40°C, and the time of the RAFT emulsion polymerization is 17h; the freezing and ventilation method is: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, and then thaw in room temperature water under argon filling, repeat the evacuation-ventilation-thawing operation 3 times to complete the freezing and ventilation; the temperature of the freezing conditions is -196°C; the evacuation time is 3min;

[0109] (3) 1.4 mL of the RAFT soap-free emulsion obtained in step (2) is applied on a polytetrafluoroethylene mold, followed by drying and film-forming and reduced pressure heat treatment in sequence to obtain a water-plastic latex film; the coating thickness is 1.2 mm; the drying film-forming temperature is 40° C., the drying film-forming time is 6 h, and the drying film-forming is carried out in an oven; the reduced pressure heat treatment temperature is 120° C., the vacuum degree of the reduced pressure heat treatment is -0.1 MPa, the reduced pressure heat treatment time is 12 h, and the reduced pressure heat treatment is carried out in a vacuum oven.

[0110] The water-plastic conditions of the water-plastic latex film prepared in Example 2 are as follows: after being immersed in ultrapure water at 0°C for 50 seconds, it becomes soft and plastic and can be formed into various complex shapes, and then dried at room temperature to obtain a water-plastic latex film with a fixed shape.

[0111] Example 3

[0112] A method for preparing a water-plastic latex film comprises the following steps:

[0113] (1) The preparation method of a hydrophilic macromolecular RAFT agent is as follows: 0.0308 g of a RAFT agent, 0.0026 g of an initiator, 4.5638 g of a monomer and 8.272 g of a solvent are mixed and then ultrasonically dissolved, followed by freezing and ventilation, followed by RAFT solution polymerization, and finally quenching in liquid nitrogen while ventilating to quench the reaction, after rotary evaporation of the solvent, dissolving it with dichloromethane and precipitating it in ice-cold n-hexane three times, followed by vacuum drying to obtain a light pink solid hydrophilic macromolecular RAFT agent; the RAFT agent is CPADB; The initiator is AIBN; the monomer is dimethylaminoethyl methacrylate; the solvent is 1,4-dioxane; the freezing and ventilation method is: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, then defrost in room temperature water under argon, repeat the evacuation-ventilation-thawing operations 3 times to complete freezing and ventilation; the temperature of the freezing condition is -196°C; the evacuation time is 3 minutes; the temperature of the RAFT solution polymerization reaction is 70°C, and the RAFT solution polymerization reaction time is 10 hours;

[0114] (2) dissolving a water-soluble initiator in acidic ultrapure water to obtain a water-soluble initiator solution with a concentration of 2 mg / mL, then dissolving 60 mg of the hydrophilic macromolecular RAFT reagent obtained in step (1) in 1.5 mL of acidic ultrapure water and dissolving it uniformly by ultrasonication to obtain a hydrophilic macromolecular RAFT reagent solution with a concentration of 40 mg / mL, adding 60 mg of an oil-soluble monomer and 327 mg of acidic ultrapure water (ensuring that the total amount of solvent is 2072 mg, i.e., the solid content of the emulsion is 5.5%) to the hydrophilic macromolecular RAFT reagent solution, and then adding 0.245 μL (containing 0.49 mg of a water-soluble initiator and 245 mg of a solvent) of the water-soluble initiator solution to form a mixed solution, followed by sequentially performing refrigeration ventilation, ultrasonication for 1 min, and RAFT emulsion polymerization to obtain a RAFT soap-free emulsion; the acidic ultrapure water is a mixture of ultrapure water and HCl aqueous solution, and the pH value of the acidic ultrapure water is 1.0; the mass ratio of the hydrophilic macromolecular RAFT agent to the oil-soluble monomer is 1:1; the oil-soluble monomer is n-butyl methacrylate; the water-soluble initiator is VA-044; the temperature of the RAFT emulsion polymerization is 40°C, and the time of the RAFT emulsion polymerization is 12h; the freezing and ventilation method is: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, then thaw in room temperature water under argon filling, repeat the evacuation-ventilation-thaw operations 3 times to complete the freezing and ventilation; the temperature of the freezing conditions is -196°C; the evacuation time is 3min;

[0115] (3) 1.4 mL of the RAFT soap-free emulsion obtained in step (2) is applied on a polytetrafluoroethylene mold, followed by drying and film-forming and reduced pressure heat treatment in sequence to obtain a water-plastic latex film; the coating thickness is 1.2 mm; the drying film-forming temperature is 40° C., the drying film-forming time is 6 h, and the drying film-forming is carried out in an oven; the reduced pressure heat treatment temperature is 120° C., the vacuum degree of the reduced pressure heat treatment is -0.1 MPa, the reduced pressure heat treatment time is 12 h, and the reduced pressure heat treatment is carried out in a vacuum oven.

[0116] The water plastic conditions of the water-plastic latex film prepared in Example 3 are as follows: after being immersed in acidic ultrapure water at 0°C (the acidic ultrapure water is a mixture of ultrapure water and HCl aqueous solution, and the pH value of the acidic ultrapure water is 1.0) for 50 seconds, it becomes soft and plastic and can be formed into various complex shapes. Then, it can be dried at room temperature to obtain a water-plastic latex film with a fixed shape.

[0117] Example 4

[0118] A method for preparing a water-plastic latex film comprises the following steps:

[0119] (1) The preparation method of the hydrophilic macromolecular RAFT agent is as follows: 0.0461 g of RAFT agent, 0.0039 g of initiator, 6.8559 g of monomer and 12.427 g of solvent are mixed and then ultrasonically dissolved, followed by freezing and ventilation, followed by RAFT solution polymerization, and finally quenching in liquid nitrogen while ventilating to quench the reaction, after rotary evaporation of the solvent, it is dissolved in dichloromethane and precipitated in ice-cold n-hexane three times, followed by vacuum drying to obtain a light pink solid hydrophilic macromolecular RAFT agent; the RAFT agent is CPADB ; The initiator is AIBN; the monomer is dimethylaminoethyl methacrylate; the solvent is 1,4-dioxane; the freezing and ventilation method is: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, then thaw in room temperature water under argon, repeat the evacuation-ventilation-thaw operations 3 times to complete the freezing and ventilation; the temperature of the freezing condition is -196°C; the evacuation time is 3 minutes; the temperature of the RAFT solution polymerization reaction is 70°C, and the RAFT solution polymerization reaction time is 9 hours;

[0120] (2) dissolving a water-soluble initiator in acidic ultrapure water to obtain a water-soluble initiator solution with a concentration of 2 mg / mL, then dissolving 60 mg of the hydrophilic macromolecular RAFT agent obtained in step (1) in 1.5 mL of acidic ultrapure water and dissolving it uniformly by ultrasonication to obtain a hydrophilic macromolecular RAFT agent solution with a concentration of 40 mg / mL, adding 72 mg of an oil-soluble monomer and 490 mg of acidic ultrapure water (ensuring that the total amount of solvent is 2280 mg, i.e., the emulsion solid content is 5.5%) to the hydrophilic macromolecular RAFT agent solution, and then adding 0.29 μL (containing 0.58 mg of a water-soluble initiator and 290 mg of a solvent) of the water-soluble initiator solution to form a mixed solution, followed by sequentially performing refrigeration ventilation, ultrasonic treatment for 1 min, and RAFT emulsion polymerization to obtain a RAFT soap-free emulsion; the acidic ultrapure water is ultrapure water. The mixture is formed by mixing water and HCl aqueous solution, and the pH value of the acidic ultrapure water is 1.0; the mass ratio of the hydrophilic macromolecular RAFT agent and the oil-soluble monomer is 1:1.2; the oil-soluble monomers are hard segment monomers and soft segment monomers, the hard segment monomer is methyl methacrylate, and the soft segment monomer is n-butyl methacrylate, and the mass ratio of the hard segment monomer to the soft segment monomer is 1:1.5; the water-soluble initiator is VA-044; the temperature of the RAFT emulsion polymerization is 40°C, and the time of the RAFT emulsion polymerization is 12h; the freezing and ventilation method is: first evacuate the air under freezing conditions, then fill with argon for ventilation, repeat the evacuation and ventilation operations 3 times, and then thaw in room temperature water under argon filling, repeat the evacuation-ventilation-thawing operations 3 times to complete the freezing and ventilation; the temperature of the freezing conditions is -196°C; the evacuation time is 3min;

[0121] (3) 1.4 mL of the RAFT soap-free emulsion obtained in step (2) is applied on a polytetrafluoroethylene mold, followed by drying and film-forming and reduced pressure heat treatment in sequence to obtain a water-plastic latex film; the coating thickness is 1.2 mm; the drying film-forming temperature is 40° C., the drying film-forming time is 6 h, and the drying film-forming is carried out in an oven; the reduced pressure heat treatment temperature is 120° C., the vacuum degree of the reduced pressure heat treatment is -0.1 MPa, the reduced pressure heat treatment time is 12 h, and the reduced pressure heat treatment is carried out in a vacuum oven.

[0122] The water plastic conditions of the water-plastic latex film prepared in Example 4 are as follows: after being immersed in acidic ultrapure water at 0°C (the acidic ultrapure water is a mixture of ultrapure water and HCl aqueous solution, and the pH value of the acidic ultrapure water is 1.0) for 50 seconds, it becomes soft and plastic and can be formed into various complex shapes. Then, it can be dried at room temperature to obtain a water-plastic latex film with a fixed shape.

[0123] Comparative Example 1

[0124] In the step (2), the oil-soluble monomer is only methyl methacrylate, and other conditions are the same as those in Example 1.

[0125] Comparative Example 2

[0126] In step (2), the oil-soluble monomer is only methyl methacrylate, and other conditions are the same as those in Example 2.

[0127] Comparative Example 3

[0128] In step (2), the oil-soluble monomer is only methyl methacrylate, and other conditions are the same as those in Example 3.

[0129] Comparative Example 4

[0130] In the step (2), the oil-soluble monomer is only n-butyl methacrylate, and the amount of n-butyl methacrylate is 1800 mg. The mass ratio of the hydrophilic macromolecular RAFT agent to the oil-soluble monomer is 1:30. Other conditions are the same as those in Example 4.

[0131] The physical pictures of the products prepared in Comparative Examples 1 to 3 are as follows Fig.11 shown. Fig.11 In the figure, from top to bottom are the products prepared in Comparative Examples 1 to 3. Fig.11 It can be seen that when the oil-soluble monomer is only methyl methacrylate, the prepared product cannot form a film at all and will break.

[0132] Although the technical solution provided in Comparative Example 4 can prepare the latex film, the latex film has no water plasticity. The latex film obtained in Comparative Example 4 was immersed in 0°C acidic ultrapure water (the acidic ultrapure water is a mixture of ultrapure water and HCl aqueous solution, and the pH value of the acidic ultrapure water is 1.0) for 50 seconds. Fig.12 As shown. Fig.12 It can be seen that the latex film prepared in Comparative Example 4 turns white after soaking (the latex film prepared in the present invention emits blue light, such as Figure 3 ) becomes wrinkled and hard, does not soften, and cannot be deformed, indicating that the latex film obtained in the comparative example does not have water plasticity.

[0133] By comparing Examples 1 to 4 with Comparative Examples 1 to 4, it can be seen that the present invention can control the type and proportion of oil-soluble monomers, the amount relationship of the hydrophilic macromolecular RAFT agent and the oil-soluble monomers in the process of preparing the RAFT soap-free emulsion, so as to not only ensure that the RAFT soap-free emulsion is easy to form a film, but also make the obtained latex film have excellent mechanical properties, and the latex film can become soft and plastic after a short time of water treatment, and can be formed into various complex shapes, and has excellent water plasticity.

[0134] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a water-plastic latex film, comprising the following steps: (1) mixing a hydrophilic macromolecular RAFT agent solution, an oil-soluble monomer and a solvent, then adding a water-soluble initiator solution to form a mixed solution, and sequentially subjecting the mixed solution to freezing ventilation, ultrasonic treatment and RAFT emulsion polymerization to obtain a RAFT soap-free emulsion; the oil-soluble monomer includes a soft segment monomer; the mass ratio of the hydrophilic macromolecular RAFT agent to the oil-soluble monomer in the mixed solution is 1:(1-5); (2) The RAFT soap-free emulsion obtained in step (1) is used to prepare a water-plastic latex film by a coating film-forming method.

2. The preparation method according to claim 1, characterized in that: The preparation method of the hydrophilic macromolecular RAFT agent in step (1) is: mixing the RAFT agent, initiator, monomer and solvent, dissolving them by ultrasonication, then freezing and ventilating, then performing RAFT solution polymerization reaction, and finally sequentially performing quenching, solvent rotary evaporation, precipitation purification and vacuum drying to obtain the hydrophilic macromolecular RAFT agent.

3. The preparation method according to claim 2, characterized in that: The RAFT agent is 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid and / or 4-cyanopentanoyl dithiobenzoic acid; the initiator is one or more of azobisisobutyronitrile, azobisisoheptanoonitrile and azobiscyclohexylcarbonitrile; the monomer is one or more of dimethylaminoethyl methacrylate, methacrylic acid, glycidyl methacrylate and oligoethylene glycol methacrylate; and the solvent is one or more of 1,4-dioxane, tetrahydrofuran and N,N-dimethylformamide.

4. The preparation method according to claim 2, characterized in that: The temperature of the RAFT solution polymerization reaction is 60-80° C., and the time of the RAFT solution polymerization reaction is 6-15 hours.

5. The preparation method according to claim 1, characterized in that: In step (1), the water-soluble initiator is 2,2'-azabis(2-imidazoline) dihydrochloride and / or 4,4'-azobis(4-cyanovaleric acid); and the solvent is one or more of ultrapure water, acidic ultrapure water, sodium chloride solution and phosphate buffer solution.

6. The preparation method according to claim 1, characterized in that: The temperature of the RAFT emulsion polymerization in the step (1) is 40 to 60° C., and the time of the RAFT emulsion polymerization is 12 to 20 hours.

7. The preparation method according to claim 1, characterized in that: The method of freezing and ventilation in step (1) is: first evacuate the air under freezing conditions, then fill in argon gas for ventilation, repeat the evacuation and ventilation operations 3 times, then thaw in room temperature water under argon gas filling, repeat the evacuation-ventilation-thawing operations 3 to 4 times to complete the freezing and ventilation.

8. The preparation method according to claim 1, characterized in that: The coating film-forming method in step (2) is to coat the RAFT soap-free emulsion, then sequentially dry the emulsion to form a film and perform a reduced pressure heat treatment to obtain a water-plastic latex film.

9. The water-plastic latex film prepared by the preparation method according to any one of claims 1 to 8.

10. The water-plastic latex film according to claim 9, characterized in that: The water plastic conditions of the water plastic latex film are soaking in water; the pH of the water is 0 to 9.0; the soaking temperature is 0 to 40° C., and the soaking time is 50 to 90 seconds.

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