Composition for preparing vinyl acetate-ethylene copolymer emulsion for ceramic tile adhesive, copolymer emulsion and preparation method and application of copolymer emulsion

Abstract

The invention relates to the technical field of vinyl acetate-ethylene copolymer emulsion, and discloses a composition for preparing the vinyl acetate-ethylene copolymer emulsion for tile glue, the copolymer emulsion, and a preparation method and application of the copolymer emulsion. 6-8 parts by weight of ethylene; 26-28 parts by weight of a pre-emulsified monomer; 2.2 to 2.4 parts by weight of a repolymerization grafting emulsion; and 39-40 parts by weight of water. The vinyl acetate-ethylene copolymer emulsion is applied to ceramic tile adhesives, has the advantages of good water resistance and high strength, and can be used in the field of ceramic tile adhesives.

Description

Technical Field

[0001] This invention relates to the field of vinyl acetate-ethylene copolymer emulsion technology, specifically to a composition and copolymer emulsion for preparing vinyl acetate-ethylene copolymer emulsion for tile adhesive, as well as the preparation method and application thereof. Background Technology

[0002] Traditional tile adhesive powder is made from vinyl acetate-ethylene copolymer emulsion, which is rapidly dried under high-speed spray drying to become redispersible latex powder. This latex powder is then mixed with cellulose, cement, amylase, heavy calcium carbonate powder, and water to form tile adhesive for tile laying. With rising living standards and changing aesthetic preferences, the variety of tiles has increased, with larger tiles becoming a trend. The increased weight of tiles means ordinary tile adhesives can no longer support the weight of these tiles. Furthermore, some exterior wall tiles, exposed to wind, sun, and rain, have weakened bonding strength and are prone to slipping and detachment, posing significant safety hazards. Interior wall tiles also experience slipping, detachment, and hollowing.

[0003] CN113896485B discloses a high-strength tile adhesive that uses cement-based inorganic binders, inorganic fillers, and cellulose-based organic binders, and undergoes a vibration mixing process for pretreatment. The adhesive has good fluidity, excellent adhesion in a wet state, does not drip when stationary, and exhibits excellent bonding strength and is not easily peeled off after solidification, possessing high mechanical strength.

[0004] CN115572113B utilizes recycled artificial sand and industrial waste mineral powder from a cement plant aggregate production line. The introduction of geopolymers increases the alkalinity of the tile adhesive. The mineral powder and fly ash used, activated by dry water glass, form a composite gel network structure of hydrated calcium silicate (CSH) and hydrated sodium aluminosilicate (NASH). The incorporation of recycled stone powder fine aggregate and artificial sand coarse aggregate fills the various pore sizes between the gels, not only improving the strength and water resistance of the tile adhesive but also overcoming the adverse effect of significant shrinkage of the geopolymer. This paper provides a geopolymer tile adhesive, its preparation method, and its applications.

[0005] CN115305016A discloses a two-component waterproof tile adhesive composition. Through the synergistic effect of components such as silicate solution, thickener, defoamer, water, talc, sand, and mineral powder, it exhibits strong adhesion and excellent impermeability. Simultaneously, this composition has a low film shrinkage rate and good adhesion, providing strong waterproofing for low-absorption tiles. Its application in low-absorption tiles eliminates the need for tile backing adhesive, saving costs and effectively reducing film shrinkage and tile detachment during the film-forming process. It is suitable for both low-absorption and high-absorption tiles.

[0006] The aforementioned patents all relate to tile adhesives, mainly concerning the development of downstream application technologies for tile adhesives. As modern tile laying places higher demands on the strength, humidity resistance, and weather resistance of tile adhesives, it is necessary to develop a high-strength tile adhesive to simultaneously meet people's dual needs for improving architectural aesthetics and performance. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing tile adhesives in terms of strength and humidity resistance. This invention provides a composition for preparing a vinyl acetate-ethylene copolymer emulsion for tile adhesive, the copolymer emulsion itself, its preparation method, and its application. This vinyl acetate-ethylene copolymer emulsion, when applied to tile adhesive, has the advantages of good water resistance and high strength, and can be used in the field of tile adhesives.

[0008] To achieve the above objectives, a first aspect of the present invention provides a composition for preparing a vinyl acetate-ethylene copolymer emulsion for tile adhesive, wherein, by weight parts, the composition comprises:

[0009] Vinyl acetate: 24-26 parts by weight;

[0010] Ethylene: 6-8 parts by weight;

[0011] Pre-emulsified monomer: 26-28 parts by weight;

[0012] Repolymerized graft emulsion: 2.2-2.4 parts by weight;

[0013] Water: 39-40 parts by weight.

[0014] A second aspect of the present invention provides a method for preparing a copolymer emulsion using the aforementioned composition for preparing a vinyl acetate-ethylene copolymer emulsion for tile adhesive, wherein the method comprises:

[0015] (1) Mix cellulose, polyvinyl alcohol, emulsifier, vinyl acetate, ethylene and water in contact;

[0016] (2) Under certain temperature and pressure, each reactant in step (1) is brought into contact with an oxidant, a reducing agent, a portion of an initiator, and a pre-emulsified monomer to carry out the first reaction;

[0017] (3) The product of step (2) is contacted with another part of the initiator for a second reaction and degassing treatment, and the reaction product is contacted with the repolymerized graft emulsion, treatment aid and pH adjuster for post-treatment to obtain vinyl acetate-ethylene copolymer.

[0018] A third aspect of the present invention provides a vinyl acetate-ethylene copolymer emulsion for tile adhesive prepared by the method described above.

[0019] The fourth aspect of the present invention provides an application of the aforementioned vinyl acetate-ethylene copolymer emulsion in tile adhesive.

[0020] The technical solution of the present invention has the following advantages through the above technical solution:

[0021] (1) The present invention uses cellulose and polyvinyl alcohol as protective colloids to improve the water retention and dispersibility of tile adhesive, improve the operability during actual construction, stabilize the wet strength of the emulsion after powdering, and make the adhesive powder, calcium powder, cement and sand bonded together with toughness.

[0022] (2) The present invention uses methyl methacrylate hard monomer to increase the strength of powder.

[0023] (3) This invention uses ethylene tert-carbonate to improve the water resistance of the powder.

[0024] (4) In this invention, styrene-butadiene latex is introduced in the post-treatment stage, so that the residual vinyl acetate is grafted with the styrene-butadiene latex. The excellent water resistance, weather resistance and high temperature resistance of styrene-butadiene latex are used to stabilize and improve the strength of the latex.

[0025] (5) The vinyl acetate-ethylene copolymer emulsion obtained by this invention has no residue, high emulsion yield, high sizing efficiency, and low energy consumption. It has little odor and low total VOC, demonstrating high efficiency and environmental friendliness.

[0026] (6) The raw materials of this invention are widely available, the existing production process is not significantly modified, the preparation process is not much different from that of general emulsions, no special equipment is required, industrial implementation is convenient, and the application prospects are broad.

[0027] (7) Although the cost increases slightly, the performance is 2-3 times stronger than that of ordinary tile adhesive. Because cellulose has been added at the source, it does not need to be added downstream. In addition, the solid content is high, which saves costs for downstream powder spraying. Detailed Implementation

[0028] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] As previously stated, the first aspect of the present invention provides a composition for preparing a vinyl acetate-ethylene copolymer emulsion for tile adhesive, wherein, by weight parts, the composition comprises:

[0030] Vinyl acetate: 24-26 parts by weight;

[0031] Ethylene: 6-8 parts by weight;

[0032] Pre-emulsified monomer: 26-28 parts by weight;

[0033] Repolymerized graft emulsion: 2.2-2.4 parts by weight;

[0034] Water: 39-40 parts by weight.

[0035] According to the present invention, the composition further comprises:

[0036] Cellulose: 0.06-0.08 parts by weight;

[0037] Polyvinyl alcohol: 0.9-1.1 parts by weight;

[0038] Emulsifier: 1.9-2.1 parts by weight;

[0039] Reducing agent: 0.21-0.23 parts by weight;

[0040] Oxidizing agent: 0.09-0.11 parts by weight;

[0041] pH adjuster: 0.25-0.27 parts by weight;

[0042] Post-treatment agent: 0.02-0.04 parts by weight.

[0043] The inventors of this invention discovered that using vinyl acetate and ethylene as the main polymerizing monomers, and using cellulose and polyvinyl alcohol as protective colloids, is beneficial to improving the water retention and dispersibility of tile adhesive, thus improving its operability during actual construction. Adding acrylates can improve the strength of the adhesive film. At the same time, adding glycidyl ester and ethylene tert-carbonate to the functional monomers improves the water resistance and weather resistance after film formation. Finally, by grafting styrene-butadiene emulsion in a post-treatment repolymerization process, a special vinyl acetate-ethylene emulsion with good water resistance, high strength, and strong weather resistance can be synthesized and applied to tile adhesive.

[0044] According to the present invention, the pre-emulsified monomer is selected from one or more of acrylates, vinyl tert-carbonate and vinyl acetate; preferably, the acrylate is selected from one of methyl methacrylate, methyl acrylate, ethyl acrylate and butyl acrylate.

[0045] According to the present invention, the repolymerized grafted emulsion is a styrene-butadiene emulsion.

[0046] According to the present invention, the emulsifier is selected from one or more of octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, and fatty alcohol polyoxyethylene ether.

[0047] According to the present invention, the cellulose is hydroxycellulose.

[0048] According to the present invention, the degree of polymerization of the polyvinyl alcohol is 500-2000, and the degree of hydrolysis is 80-99.5%. In the present invention, one or more of PVA 1788, PVA 0588, and PVA 1799 are preferred.

[0049] According to the present invention, the reducing agent is one or more selected from ascorbate, tartrate, bisulfite, thiosulfate and formaldehyde sulfoxylate.

[0050] According to the present invention, the oxidant is one or more selected from hydrogen peroxide, potassium persulfate, ammonium persulfate and tert-butyl hydrogen peroxide.

[0051] According to the present invention, the pH adjuster is one or more selected from bicarbonate, acetate, phosphate and sodium hydroxide.

[0052] According to the present invention, the post-treatment agent is the aforementioned reducing agent and oxidizing agent.

[0053] A second aspect of the present invention provides a method for preparing a copolymer emulsion using the aforementioned composition for preparing a vinyl acetate-ethylene copolymer emulsion for tile adhesive, wherein the preparation method includes:

[0054] (1) Mix cellulose, polyvinyl alcohol, emulsifier, vinyl acetate, ethylene and water in contact;

[0055] (2) Under certain temperature and pressure, each reactant in step (1) is brought into contact with an oxidant, a reducing agent, a portion of an initiator, and a pre-emulsified monomer to carry out the first reaction;

[0056] (3) The product of step (2) is contacted with another part of the initiator for a second reaction and degassing treatment, and the reaction product is contacted with the repolymerized graft emulsion, treatment aid and pH adjuster for post-treatment to obtain vinyl acetate-ethylene copolymer.

[0057] In this invention, the method uses cellulose and polyvinyl alcohol as protective colloids, which helps to improve the water retention and dispersibility of tile adhesive and improves the operability during actual construction; adding acrylates can improve the strength of the adhesive film; at the same time, glycidyl ester and ethylene tert-carbonate are added to the functional monomers to improve the water resistance and weather resistance after film formation; finally, styrene-butadiene emulsion is grafted in the post-treatment repolymerization process.

[0058] According to the present invention, in step (2): the conditions of a certain temperature and pressure include: a temperature of 54-62°C and a pressure of 3-3.3 MPa.

[0059] According to the present invention, the conditions for the first reaction include: a temperature of 70-74°C, a pressure of 5-5.5 MPa, and a time of 45-55 min.

[0060] According to the present invention, the addition rates of the oxidant and the reducing agent are the same or different, each being 10-13 kg / min.

[0061] According to the present invention, the addition rate of the initiator is not particularly limited and can be dynamically controlled by computer temperature control.

[0062] And / or, in step (3), the conditions for the second reaction include: a temperature of 75-78°C and a pressure of 1.4-1.5 MPa.

[0063] According to a particularly preferred embodiment of the present invention, the method for preparing the vinyl acetate-ethylene copolymer includes:

[0064] (A) Preparation of raw materials

[0065] (1) Preparation of surfactant: Weigh 0.06-0.08 parts of cellulose, 0.9-1.1 parts of polyvinyl alcohol, 0.21-0.23 parts of reducing agent and 30-32 parts of deionized water and pour them into the reaction vessel. Stir at room temperature for 15 minutes and then heat to 85℃ to dissolve.

[0066] (2) Preparation of oxidant solution system: Add 4-6 parts of deionized water and 0.09-0.11 parts of oxidant to the oxidant tank and stir;

[0067] (3) Preparation of pre-emulsified monomer: Add 1.9-2.1 parts of emulsifier, 1-3 parts of methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 6-7 parts of ethylene tert-carbonate and 16-18 parts of vinyl acetate to the monomer tank and mix and emulsify.

[0068] (4) Repolymerization of grafted emulsion: Add 2.2-2.4 parts of styrene-butadiene emulsion to the monomer tank;

[0069] (5) Preparation of post-treatment agent: 0.01-0.03 parts oxidant, 0.8 parts deionized water, 0.008-0.01 parts reducing agent and 0.8 parts deionized water;

[0070] (6) Prepare pH adjuster: 0.25-0.27 parts pH adjuster and 1.6 parts deionized water;

[0071] (B) Production by feeding materials

[0072] (1) Add 32-34 parts of surfactant solution and 24-26 parts of initial vinyl acetate monomer to the reactor, and add ethylene to the reactor;

[0073] (2) When the temperature reaches 54-62℃ and the pressure reaches 3.0-3.3MPa, add the initial oxidant and reducing agent at a rate of 10-13kg / min. When the temperature reaches 70-74℃, clear the pressure and cool completely. Then, control the reaction and the rate of initiator addition by computer. Continue to increase the pressure of the reactor to 5.0-5.5MPa and continue to add 26-28 parts of pre-emulsified monomer. The reaction is completed in about 45-55 minutes.

[0074] (3) When the temperature is 75-78℃ and the pressure is 1.4-1.5MPa, the finishing period begins. The remaining initiator is added dropwise. A total of 0.09-0.11 parts of oxidant are used for one batch of material. After degassing to the degassing tank, 2.2-2.4 parts of styrene-butadiene emulsion are added from the monomer tank 3, followed by 0.018-0.03 parts of post-treatment aid. The material is then post-treated for 60 minutes. After cooling, 0.25-0.27 parts of pH adjuster are added. The material is kept warm for 10 minutes before being discharged, filtered, and packaged.

[0075] In this invention, it should be noted that in step (A), during the raw material preparation process, each reactant is dissolved in deionized water in advance according to process requirements; this pre-dissolution is necessary. The material added in step (B) is an aqueous solution of each reactant from step (A).

[0076] A third aspect of the present invention provides a vinyl acetate-ethylene copolymer emulsion for tile adhesive prepared by the method described above.

[0077] In this invention, it should be noted that the vinyl acetate-ethylene copolymer emulsion also contains residual monomers, wherein, based on the total weight of the vinyl acetate-ethylene copolymer emulsion, the content of residual monomers is ≤0.1%.

[0078] In this invention, the water is preferably deionized water.

[0079] According to the present invention, the vinyl acetate-ethylene copolymer emulsion prepared by the combined action of functional monomer modification, special protective colloid and post-grafting technology has a viscosity of 1000-2500 mPa·s and a solid content of 60-61%.

[0080] According to the present invention, the density of the vinyl acetate-ethylene copolymer emulsion is 1.06-1.08 g / cm³. 3 .

[0081] According to the present invention, the ethylene mass fraction in the vinyl acetate-ethylene copolymer emulsion is 9-11%.

[0082] According to the present invention, the film strength of the vinyl acetate-ethylene copolymer emulsion is 10-12 MPa, the elongation is 400-600%, and the strength of the tile adhesive after being powdered is 1.0-1.5 MPa. The adhesive powder obtained by spray drying the emulsion is used in the field of tile adhesive powder and has the characteristics of high strength, good water resistance and weather resistance.

[0083] A fourth aspect of the present invention provides an application of the aforementioned vinyl acetate-ethylene copolymer emulsion in tile adhesive.

[0084] The present invention will be described in detail below through embodiments.

[0085] In the following examples and comparative examples:

[0086] Methods for measuring various indicators

[0087] (1) Determination of solid content:

[0088] Instrument: HR83 infrared moisture analyzer, stainless steel weighing pan;

[0089] Operating conditions: Standard temperature rise 165℃;

[0090] Method: Adjust the control panel to automatically open the sample addition chamber, add the weighing pan, remove the tare, quickly add 1-2g of sample, level it, press the start button, and directly read the analysis results after the measurement is completed;

[0091] (2) Viscosity determination:

[0092] Instruments: constant temperature water bath 25±0.2℃, Brookfield viscometer;

[0093] Method: Place the sample in a water bath at 25 ± 0.2℃ and keep it at that temperature for 30 minutes. Select the correct rotor, adjust the mark on the shaft to match the emulsion surface, start the viscometer motor, and after rotating for 45 seconds, take the reading directly.

[0094] (3) Determination of ethylene:

[0095] Instruments: Infrared spectrometer, infrared drying lamp, water-resistant AgBr slides;

[0096] Method: Read the value directly according to the operating steps;

[0097] (4) Density test

[0098] Density determination method: Place a 100ml specific gravity cup and its lid on a balance to remove the tare weight. Then pour the emulsion into the 100ml specific gravity cup, cover it, wipe away any overflowing emulsion, and weigh it again. Divide the resulting weight by 100 to obtain the emulsion density.

[0099] (5) Membrane strength / elongation test

[0100] Instrument: Universal testing tensile machine

[0101] Method: Cut dumbbell type I specimens that meet the requirements of GB / T528, and draw parallel marking lines with a spacing of 25 mm. Measure the thickness at three points in the middle and at both ends of the specimen marking line with a thickness gauge, and take the arithmetic mean as the specimen thickness. Adjust the clamping distance of the tensile testing machine to about 70 mm, clamp the specimen on the testing machine, keep the center line of the specimen length direction in line with the center of the testing machine clamp, and perform tensile testing at a tensile speed of 200 mm / min until fracture, and record the data.

[0102] (6) Strength test of tile adhesive after powdering

[0103] Instrument: Multifunctional mortar pull-out tester

[0104] Method: Use a 50-mm-diameter bonded tile as the specimen and bond it perpendicularly to the substrate in the glue; wait for 24 hours, pull out the specimen until fracture, and record the failure load;

[0105] (7) Water resistance test

[0106] Water resistance determination method: Normal temperature immersion test method (GB / T1733-1993), water temperature is (23±2)°C; Add distilled water or deionized water to a glass water tank, adjust the water temperature to the specified temperature, and maintain this temperature throughout the test process. Immerse 2 / 3 of the test glue film in water for the specified time and then take it out, dry it with filter paper, and check for phenomena such as loss of gloss, color change, blistering, wrinkling, whitening, and rubbing slurry. If not, the product is specified as qualified according to the regulations.

[0107] Raw materials and reagents involved in the present invention are all commercially available chemical reagents and chemical industrial raw materials without special instructions.

[0108] In the present invention, it should be noted that "parts" are all equivalent to "parts by weight".

[0109] Example 1

[0110] (A) Raw material preparation

[0111] (1) Prepare surfactant: Weigh 0.06 parts of hydroxymethyl cellulose, 0.05 parts of PVA 1788, 0.06 parts of PVA0 · 588, 0.21 parts of zinc formaldehyde sulfoxylate and 32 parts of deionized water and pour them into a reaction kettle. Stir at room temperature for 15 minutes and then heat up to 85°C for dissolution;

[0112] (2) Prepare oxidant solution system: Add 4 parts of deionized water and 0.09 parts of tert-butyl hydroperoxide to the oxidant tank and stir;

[0113] (3) Preparation of pre-emulsified monomer: Add 1.9 parts of octylphenol polyoxyethylene ether, 3 parts of methyl methacrylate, 6 parts of ethylene tert-carbonate and 16 parts of vinyl acetate to the second monomer tank and mix and emulsify.

[0114] (4) Repolymerization of grafted emulsion: 2.2 parts of styrene-butadiene emulsion were added to the monomer tank;

[0115] (5) Preparation of post-treatment agent: 0.01 parts tert-butyl hydrogen peroxide, 0.8 parts deionized water, 0.008 parts zinc sodium hydroxide and 0.8 parts deionized water;

[0116] (6) Prepare pH adjuster: 0.25 parts sodium bicarbonate and 1.6 parts deionized water;

[0117] (B) Technological Process

[0118] 32 parts of surfactant solution and 26 parts of initial vinyl acetate monomer were added to the reactor, and ethylene was added to the reactor. When the temperature reached 57℃ and the pressure reached 3.1MPa, the initial oxidant and reducing agent were added at a rate of 12kg / min. The reactor was then zeroed at 71℃ and completely cooled. The reaction and initiator addition rate were then controlled by computer. The reactor pressure was increased to 5.3MPa, and 27 parts of pre-emulsified monomer were added dropwise, which was completed in about 52 minutes. When the temperature reached 77℃ and the pressure reached 1.5MPa, the finishing period began, and the remaining initiator was added dropwise. After degassing, 2.2 parts of styrene-butadiene emulsion were added from the monomer tank, followed by 0.018 parts of post-treatment aids. The post-treatment was carried out for 60 minutes. After cooling, 0.25 parts of pH adjuster were added, and the mixture was kept warm for 10 minutes before being discharged, filtered, and packaged to obtain vinyl acetate-ethylene copolymer emulsion. The performance parameters of the vinyl acetate-ethylene copolymer emulsion are shown in Table 1.

[0119] Table 1

[0120] Appearance White emulsion Solid content, % 60.2 Viscosity, mPa·s 1580 Ethylene content, % 10.9 <![CDATA[Density, g / cm 3 > 1.07 Membrane strength, MPa 11.5 Membrane elongation, % 520 After being ground into powder, the strength of the tile adhesive is measured in MPa. 1.4 Water resistance Not turning white

[0121] It should be noted that "non-whitening" in water resistance means that the membrane does not turn white or turn white after being soaked in water, which indicates good water resistance.

[0122] Example 2

[0123] (A) Raw material preparation

[0124] (1) Preparation of surfactant: Weigh 0.07 parts hydroxyethyl cellulose, 1 part polyvinyl alcohol, 0.22 parts sodium isoascorbate and 31 parts deionized water and pour them into the reaction vessel. Stir at room temperature for 15 minutes and then heat to 85°C to dissolve.

[0125] (2) Preparation of oxidant solution system: Add 5 parts deionized water and 0.1 parts hydrogen peroxide oxidant to the oxidant tank and stir;

[0126] (3) Preparation of pre-emulsified monomer: Add 2 parts nonylphenol polyoxyethylene ether, 2 parts methyl acrylate, 7 parts ethylene tert-carbonate and 17 parts vinyl acetate to the monomer tank and mix and emulsify.

[0127] (4) Repolymerization of grafted emulsion: 2.3 parts of styrene-butadiene emulsion were added to the monomer three tanks;

[0128] (5) Preparation of post-treatment agent: 0.02 parts hydrogen peroxide and 0.8 parts deionized water, 0.009 parts sodium isoascorbate and 0.8 parts deionized water;

[0129] (6) Prepare pH adjuster: 0.26 parts sodium hydroxide and 1.6 parts deionized water;

[0130] (B) Technological Process

[0131] 32 parts of surfactant solution and 25 parts of initial vinyl acetate monomer were added to the reactor, and ethylene was added to the reactor. When the temperature reached 59℃ and the pressure reached 3.1MPa, the initial oxidant and reducing agent were added at a rate of 11kg / min. The reactor was then zeroed at 71℃ and completely cooled. The reaction and initiator addition rate were then controlled by computer. The reactor pressure was increased to 5.4MPa, and 28 parts of pre-emulsified monomer were added dropwise, which was completed in about 49 minutes. When the temperature reached 77℃ and the pressure reached 1.5MPa, the finishing period began, and the remaining initiator was added dropwise. After degassing, 2.3 parts of styrene-butadiene emulsion were added from the monomer tank, followed by 0.029 parts of post-treatment aids. The post-treatment was carried out for 60 minutes. After cooling, 0.26 parts of pH adjuster were added, and the mixture was kept warm for 10 minutes before being discharged, filtered, and packaged to obtain vinyl acetate-ethylene copolymer emulsion. The performance parameters of the vinyl acetate-ethylene copolymer emulsion are shown in Table 2.

[0132] Table 2

[0133] Appearance White emulsion Solid content, % 60.5 Viscosity, mPa·s 2150 Ethylene content, % 10.1 <![CDATA[Density, g / cm 3 > 1.07 Membrane strength, MPa 12.1 Membrane elongation, % 475 After being ground into powder, the strength of the tile adhesive is measured in MPa. 1.3 Water resistance Not turning white

[0134] Example 3

[0135] (A) Raw material preparation

[0136] (1) Preparation of surfactant: Weigh 0.08 parts of hydroxypropyl cellulose, 1.1 parts of polyvinyl alcohol, 0.23 parts of potassium tartrate and 30 parts of deionized water and pour them into the reaction vessel. Stir at room temperature for 15 minutes and then heat to 85°C to dissolve.

[0137] (2) Preparation of oxidant solution system: Add 6 parts of deionized water and 0.11 parts of hydrogen peroxide to the oxidant tank and stir;

[0138] (3) Preparation of pre-emulsified monomer: Add 2.1 parts of fatty acid polyoxyethylene ester, 1 part of ethyl acrylate, 6 parts of ethylene tert-carbonate and 18 parts of vinyl acetate to the second monomer tank and mix and emulsify.

[0139] (4) Repolymerization of grafted emulsion: 2.4 parts of styrene-butadiene emulsion were added to the monomer tank;

[0140] (5) Preparation of post-treatment agent: 0.03 parts oxidant, 0.8 parts deionized water, 0.008 parts reducing agent and 0.8 parts deionized water;

[0141] (6) Prepare pH adjuster: 0.27 parts pH adjuster and 1.6 parts deionized water;

[0142] (B) Technological Process

[0143] 31 parts of surfactant solution and 24 parts of initial vinyl acetate monomer were added to the reactor, and ethylene was added to the reactor. When the temperature reached 62℃ and the pressure reached 3.3MPa, the initial oxidant and reducing agent were added at a rate of 13kg / min. The reactor was then zeroed at 74℃ and completely cooled. The reaction and initiator addition rate were then controlled by computer. The reactor pressure was increased to 5.5MPa, and 27 parts of pre-emulsified monomer were added dropwise, which was completed in about 53 minutes. When the temperature reached 75℃ and the pressure reached 1.4MPa, the finishing period began, and the remaining initiator was added dropwise. After degassing, 2.4 parts of styrene-butadiene emulsion were added from the monomer tank, followed by 0.038 parts of post-treatment aids. The post-treatment was carried out for 60 minutes. After cooling, 0.27 parts of sodium hydrogen phosphate were added, and the mixture was kept warm for 10 minutes before being discharged, filtered, and packaged to obtain vinyl acetate-ethylene copolymer emulsion. The performance parameters of the vinyl acetate-ethylene copolymer emulsion are shown in Table 3.

[0144] Table 3

[0145]

[0146]

[0147] As can be seen above, the vinyl acetate-ethylene copolymer emulsion for tile adhesive prepared by the method of the present invention has the advantages of good water resistance and high strength when applied to tile adhesive.

[0148] Comparative Example 1

[0149] (A) Raw material preparation

[0150] (1) Preparation of surfactant: Weigh 0.06 parts of hydroxymethyl cellulose, 0.05 parts of PVA 1788 and 0.06 parts of PVA0588, 0.21 parts of zinc hydroxide and 32 parts of deionized water and pour them into the reaction vessel. Stir at room temperature for 15 minutes and then heat to 85°C to dissolve.

[0151] (2) Preparation of oxidant solution system: Add 4 parts of deionized water and 0.09 parts of tert-butyl hydrogen peroxide to the oxidant tank and stir;

[0152] (3) Preparation of pre-emulsified monomer: Add 1.9 parts of octylphenol polyoxyethylene ether, 3 parts of methyl methacrylate and 16 parts of vinyl acetate to the second monomer tank and mix and emulsify;

[0153] (4) Repolymerization of grafted emulsion: 2.2 parts of styrene-butadiene emulsion were added to the monomer tank;

[0154] (5) Preparation of post-treatment agent: 0.01 parts tert-butyl hydrogen peroxide, 0.8 parts deionized water, 0.008 parts zinc sodium hydroxide and 0.8 parts deionized water;

[0155] (6) Prepare pH adjuster: 0.25 parts sodium bicarbonate and 1.6 parts deionized water;

[0156] (B) Technological Process

[0157] 32 parts of surfactant solution and 26 parts of initial vinyl acetate monomer were added to the reactor, and ethylene was added to the reactor. When the temperature reached 57℃ and the pressure reached 3.1MPa, the initial oxidant and reducing agent were added at a rate of 12kg / min. The reactor was then zeroed at 71℃ and completely cooled. The reaction and initiator addition rate were then controlled by computer. The reactor pressure was increased to 5.3MPa, and 21 parts of pre-emulsified monomer were added dropwise, which was completed in about 52 minutes. When the temperature reached 77℃ and the pressure reached 1.5MPa, the finishing period began, and the remaining initiator was added dropwise. After degassing, 2.2 parts of styrene-butadiene emulsion were added from the monomer tank, followed by 0.018 parts of post-treatment aids. The post-treatment was carried out for 60 minutes. After cooling, 0.25 parts of pH adjuster were added, and the mixture was kept warm for 10 minutes before being discharged, filtered, and packaged to obtain vinyl acetate-ethylene copolymer emulsion. The performance parameters of the vinyl acetate-ethylene copolymer emulsion are shown in Table 4.

[0158] Table 4

[0159] Appearance White emulsion Solid content, % 59.2 Viscosity, mPa·s 1440 Ethylene content, % 11.1 <![CDATA[Density, g / cm 3 > 1.07 Membrane strength, MPa 11.3 Membrane elongation, % 530 After being ground into powder, the strength of the tile adhesive is measured in MPa. 0.6 Water resistance white

[0160] In Comparative Example 1, the removal of ethylene tert-carbonate resulted in an emulsion with poor water resistance, a white film, and low strength, failing to meet the requirements for use as a high-strength tile adhesive.

[0161] Comparative Example 2

[0162] (A) Raw material preparation

[0163] (1) Preparation of surfactant: Weigh 0.07 parts hydroxyethyl cellulose, 1 part polyvinyl alcohol, 0.22 parts sodium isoascorbate and 31 parts deionized water and pour them into the reaction vessel. Stir at room temperature for 15 minutes and then heat to 85°C to dissolve.

[0164] (2) Preparation of oxidant solution system: Add 5 parts deionized water and 0.1 parts hydrogen peroxide oxidant to the oxidant tank and stir;

[0165] (3) Preparation of pre-emulsified monomer: Add 2 parts nonylphenol polyoxyethylene ether, 2 parts methyl acrylate, 7 parts ethylene tert-carbonate and 17 parts vinyl acetate to the monomer tank and mix and emulsify.

[0166] (4) Preparation of post-treatment agent: 0.02 parts hydrogen peroxide and 0.8 parts deionized water, 0.009 parts sodium isoascorbate and 0.8 parts deionized water;

[0167] (5) Prepare pH adjuster: 0.26 parts sodium hydroxide and 1.6 parts deionized water;

[0168] (B) Technological Process

[0169] 32 parts of surfactant solution and 25 parts of initial vinyl acetate monomer were added to the reactor, and ethylene was added to the reactor. When the temperature reached 59℃ and the pressure reached 3.1MPa, the initial oxidant and reducing agent were added at a rate of 11kg / min. The reactor was then zeroed at 71℃ and completely cooled. The reaction and initiator addition rate were then controlled by computer. The reactor pressure was increased to 5.4MPa, and 28 parts of pre-emulsified monomer were added dropwise, which was completed in about 49 minutes. When the temperature reached 77℃ and the pressure reached 1.5MPa, the finishing period began, and the remaining initiator was added dropwise. After degassing, 0.029 parts of post-treatment aid were added to the degassing tank for 60 minutes of post-treatment. After cooling, 0.26 parts of pH adjuster were added, and the mixture was kept warm for 10 minutes before being discharged, filtered, and packaged to obtain vinyl acetate-ethylene copolymer emulsion. The performance parameters of the vinyl acetate-ethylene copolymer emulsion are shown in Table 5.

[0170] Table 5

[0171]

[0172]

[0173] In Comparative Example 2, the grafted styrene-butadiene emulsion was removed, resulting in a partially white emulsion film with a sharp decrease in film strength. When the film was powdered and used as tile adhesive, its strength also decreased, failing to meet the requirements for high-strength tile adhesive.

[0174] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composition for preparing a vinyl acetate-ethylene copolymer emulsion for tile adhesive, characterized in that, The composition comprises, by parts by weight: Vinyl acetate: 24-26 parts by weight; Ethylene: 6-8 parts by weight; Pre-emulsified monomer: 26-28 parts by weight; Repolymerized graft emulsion: 2.2-2.4 parts by weight; Water: 39-40 parts by weight.

2. The composition according to claim 1, wherein, The composition further includes: Cellulose: 0.06-0.08 parts by weight; Polyvinyl alcohol: 0.9-1.1 parts by weight; Emulsifier: 1.9-2.1 parts by weight; Reducing agent: 0.21-0.23 parts by weight; Oxidizing agent: 0.09-0.11 parts by weight; pH adjuster: 0.25-0.27 parts by weight; Post-treatment agent: 0.02-0.04 parts by weight.

3. The composition according to claim 1 or 2, wherein, The pre-emulsified monomer is one or more of acrylates, vinyl tert-carbonate and vinyl acetate; Preferably, the acrylate is selected from one or more of methyl methacrylate, methyl acrylate, ethyl acrylate, and butyl acrylate; And / or, the repolymerized grafted emulsion is a styrene-butadiene emulsion; And / or, the emulsifier is selected from one or more of octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, and fatty alcohol polyoxyethylene ether; And / or, the cellulose is hydroxycellulose.

4. The composition according to any one of claims 1-3, wherein, The protective colloid is polyvinyl alcohol; Preferably, the degree of polymerization of the polyvinyl alcohol is 500-2000; Preferably, the degree of alcoholysis of the polyvinyl alcohol is 80-99.5%.

5. A method for preparing a copolymer emulsion using the composition for preparing vinyl acetate-ethylene copolymer emulsion for tile adhesive as described in any one of claims 1-4, characterized in that, The method includes: (1) Mix cellulose, polyvinyl alcohol, emulsifier, vinyl acetate, ethylene and water in contact; (2) Under certain temperature and pressure, each reactant in step (1) is brought into contact with an oxidant, a reducing agent, a portion of an initiator, and a pre-emulsified monomer to carry out the first reaction; (3) The product of step (2) is contacted with another part of the initiator for a second reaction and degassing treatment, and the reaction product is contacted with the repolymerized graft emulsion, treatment aid and pH adjuster for post-treatment to obtain vinyl acetate-ethylene copolymer emulsion.

6. The method according to claim 5, wherein, In step (2): the conditions of a certain temperature and pressure include: temperature of 54-62℃ and pressure of 3-3.3MPa; And / or, the conditions for the first reaction include: a temperature of 70-74°C, a pressure of 5-5.5 MPa, and a time of 45-55 min; And / or, the oxidant and the reducing agent are added at the same rate, which is 10-13 kg / min.

7. The method according to claim 5, wherein, In step (3), the conditions for the second reaction include: a temperature of 75-78°C and a pressure of 1.4-1.5 MPa.

8. A vinyl acetate-ethylene copolymer emulsion for tile adhesive prepared by the method according to any one of claims 5-7.

9. The copolymer emulsion according to claim 8, wherein, The viscosity of the vinyl acetate-ethylene copolymer emulsion is 1000-2500 mPa·s, and the solid content is 60-61%. Preferably, the density of the vinyl acetate-ethylene copolymer emulsion is 1.06-1.08 g / cm³. 3 ; Preferably, the film strength of the vinyl acetate-ethylene copolymer emulsion is 10-12 MPa; Preferably, the elongation of the film of the vinyl acetate-ethylene copolymer emulsion is 400-600%.

10. The application of the vinyl acetate-ethylene copolymer emulsion as described in claim 8 or 9 in tile adhesive.

Images