Application of oil-soluble oxidants in improving the stability of vinyl acetate-ethylene copolymer emulsion

Abstract

The present invention belongs to the technical field of vinyl acetate polymers, and specifically relates to the application of an oil-soluble oxidant in improving the stability of vinyl acetate-ethylene copolymer emulsion. The present invention can significantly improve the stability of vinyl acetate-ethylene copolymer emulsion.

Description

Technical Field

[0001] The invention belongs to the technical field of vinyl acetate polymers, and particularly relates to application of an oil-soluble oxidant in improving the stability of vinyl acetate-ethylene copolymer emulsion. Background Art

[0002] Vinyl acetate-ethylene copolymer emulsion is a polymer compound emulsion prepared by emulsion polymerization using vinyl acetate and ethylene as monomers and water as a dispersion medium. Vinyl acetate-ethylene copolymer emulsion can be regarded as an ethylene internal plasticization product of vinyl acetate emulsion. Compared with polyvinyl acetate emulsion, the initial viscosity, flexibility, weather resistance, saponification resistance, water resistance and other properties of vinyl acetate-ethylene copolymer emulsion have been significantly improved. It is widely used in wood, paper, coatings, cement, fabrics, non-woven fabrics, cigarette glue, PVC and other fields ("Development of high solid content vinyl acetate-ethylene copolymer emulsion", Wu Huijiang, Adhesion, Vol. 24, No. 4, 2003, p. 15, left column, first paragraph, lines 1-3, published on December 31, 2003 (“Study on New Redox Agents for Emulsion Polymerization of Vinyl Acetate-Ethylene”, Liang Ruixue et al., Journal of Chemical Engineering of Universities, Vol. 30, No. 4, 2016, p. 843, para. 1, lines 1-2, published on August 31, 2016; “Preparation of High Solid Content Vinyl Acetate-Ethylene Copolymer Emulsion”, Wu Huijiang, Master’s Thesis of East China University of Science and Technology, 2008, p. 1, para. 1, line 1 to para. 3, line 6, published on December 31, 2008).

[0003] However, the existing vinyl acetate-ethylene copolymer emulsion has poor stability. Summary of the invention

[0004] In view of this, the object of the present invention is to provide an application of an oil-soluble oxidant in improving the stability of vinyl acetate-ethylene copolymer emulsion.

[0005] Unless otherwise specified, the parts described in the present invention refer to the parts by mass.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] The inventors conducted in-depth research to solve the above technical problems and found during the research that oil-soluble oxidants can significantly improve the stability of vinyl acetate-ethylene copolymer emulsion.

[0008] Therefore, the purpose of the present invention is to protect the use of oil-soluble oxidants in improving the stability of vinyl acetate-ethylene copolymer emulsions.

[0009] Furthermore, the oil-soluble oxidant includes one or more of tert-butyl perbenzoate, tert-butyl hydroperoxide and di-tert-butyl peroxide.

[0010] Furthermore, the oil-soluble oxidant includes a combination of tert-butyl perbenzoate and tert-butyl hydroperoxide.

[0011] Further, the mass ratio of tert-butyl perbenzoate to tert-butyl hydroperoxide is 3:3.5-3:7.

[0012] Furthermore, the mass ratio of tert-butyl perbenzoate to tert-butyl hydroperoxide is 3:5.

[0013] Furthermore, the oil-soluble oxidant includes a combination of tert-butyl perbenzoate, tert-butyl hydroperoxide and di-tert-butyl peroxide.

[0014] Furthermore, the mass ratio of tert-butyl perbenzoate, tert-butyl hydroperoxide and di-tert-butyl peroxide is 1:0.5-2:1.5-3.

[0015] Furthermore, the oil-soluble oxidant includes tert-butyl perbenzoate, tert-butyl hydroperoxide and di-tert-butyl peroxide in a mass ratio of 1:1:2.

[0016] Furthermore, the oil-soluble oxidant is added in a stepwise manner.

[0017] In the present invention, the step method refers to changing the feeding speed for multiple times, and adding part of the material for the first time, and then continuing to add the material after a period of time.

[0018] The purpose of the present invention is also to protect the preparation method of vinyl acetate-ethylene copolymer emulsion, which is prepared from raw materials including monomers, an initiation system, an emulsification system and a pH regulator. The initiation system includes an oil-soluble oxidant; the oil-soluble oxidant is added in a step-by-step manner.

[0019] In the present invention, the monomers include but are not limited to vinyl acetate monomers and ethylene monomers.

[0020] In the present invention, the emulsification system includes but is not limited to an emulsifier and a protective colloid.

[0021] In the present invention, the emulsifier may be a nonionic emulsifier, such as nonylphenol polyoxyethylene ether or fatty alcohol polyoxyethylene ether.

[0022] In the present invention, the protective colloid protects but is not limited to polyvinyl alcohol, such as one or more polyvinyl alcohols having a degree of polymerization of 500-2000 and a degree of alcoholysis of 86 mol%-92 mol%.

[0023] In the present invention, the pH adjuster may be acetate or sodium bicarbonate.

[0024] Furthermore, the preparation method of the vinyl acetate-ethylene copolymer emulsion comprises the following steps:

[0025] A. Raw material preparation

[0026] Preparing the initiating system solution: preparing the oxidant solution and the reducing agent solution in the oxidant tank and the reducing agent tank respectively;

[0027] Prepare protective colloid solution: add water and protective colloid to the dissolution tank in sequence under stirring, then heat to 85-90°C, keep warm for 80-100 minutes, and then cool to 50-60°C for standby use;

[0028] B. Feed production

[0029] Add emulsifier, water and protective colloid solution into the reactor, stir evenly, add 50%-70% of vinyl acetate, increase the temperature and introduce ethylene to increase the pressure;

[0030] When the temperature rises to 48-53°C and the pressure reaches 2.0-3.0MPa, start adding the oxidant solution and the reducing agent solution at a rate of 0.1-0.5kg / min. When the temperature in the kettle reaches 58-62°C, stop adding the oxidant solution and the reducing agent solution. After maintaining for 20-25 minutes, add the oxidant solution and the reducing agent solution at a feeding rate of 0.01-0.03kg / min. When the temperature rises to 70-74°C and the pressure reaches 4.0-5.0MPa, add the remaining vinyl acetate within 60-80 minutes, and control the temperature of the reactor to 75-78°C. After the addition of vinyl acetate, turn off ethylene, and control the feeding rate of the remaining oxidant solution and the reducing agent solution to 0.02-0.06kg / min. After 1 hour, adjust it to 0.1-0.5kg / min until the addition is complete;

[0031] Then the temperature is lowered to normal temperature and pressure, a pH adjuster is added, and the material is filtered and discharged.

[0032] The beneficial effects of the present invention are:

[0033] The invention can significantly improve the stability of vinyl acetate-ethylene copolymer emulsion.

[0034] The invention can make the particle size of the vinyl acetate-ethylene copolymer emulsion present a single peak distribution and the latex particles have a uniform size.

[0035] The vinyl acetate-ethylene copolymer emulsion prepared by the invention can be used in various bonding fields, and is particularly suitable for the field of rapid bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a particle size distribution diagram of the vinyl acetate-ethylene copolymer emulsion prepared in Example 1;

[0037] Figure 2 is a particle size distribution diagram of the vinyl acetate-ethylene copolymer emulsion prepared in Example 2;

[0038] Figure 3 is a particle size distribution diagram of the vinyl acetate-ethylene copolymer emulsion prepared in Example 3;

[0039] Figure 4 is a particle size distribution diagram of the vinyl acetate-ethylene copolymer emulsion prepared in Example 4;

[0040] Figure 5 This is a particle size distribution diagram of the vinyl acetate-ethylene copolymer emulsion prepared in Comparative Example 1;

[0041] Figure 6 This is the particle size distribution diagram of the vinyl acetate-ethylene copolymer emulsion prepared in Comparative Example 2. DETAILED DESCRIPTION

[0042] The examples are provided to better illustrate the content of the present invention, but the content of the present invention is not limited to the examples. Therefore, those skilled in the art can make non-essential improvements and adjustments to the implementation scheme according to the above content of the invention, which still fall within the protection scope of the present invention.

[0043] Example 1

[0044] The vinyl acetate-ethylene copolymer emulsion is prepared by using the following raw materials in accordance with the following steps:

[0045] A. Raw material preparation

[0046] Prepare the initiator system solution: add 3 parts of deionized water and 0.15 parts of tert-butyl perbenzoate to the oxidant tank, stir to dissolve, and obtain the oxidant solution; add 3 parts of deionized water and 0.2 parts of sodium isoascorbate to the reducing agent tank, stir to dissolve, and obtain the reducing agent solution;

[0047] Preparation of protective colloid solution: under stirring, add 20 parts of deionized water, 1.5 parts of PVA0588, 1 part of PVA1788 and 0.5 parts of PVA1792 in the dissolution tank in sequence and stir evenly, then heat to 88°C and keep at this temperature for 90 minutes, then cool to 50°C for use;

[0048] B. Feed production

[0049] Add 0.1 parts of emulsifier CA90, 18 parts of deionized water and the prepared protective colloid solution into the reactor, stir evenly, add 25 parts of vinyl acetate, increase the temperature and introduce ethylene to increase the pressure;

[0050] When the temperature rises to 48°C and the pressure reaches 3.0MPa, start adding the oxidant solution and the reducing agent solution at a rate of 0.2kg / min. When the temperature in the kettle reaches 62°C, stop adding the oxidant solution and the reducing agent solution. After maintaining for 20 minutes, continue adding the oxidant solution and the reducing agent solution at a rate of 0.01kg / min.

[0051] When the temperature rises to 70°C and the pressure reaches 4.5MPa, add 15 parts of vinyl acetate at a uniform rate within 60 minutes, and control the temperature of the reactor to 78°C. After the addition of vinyl acetate, turn off the ethylene, and control the addition rate of the remaining oxidant solution and reductant solution at 0.06kg / min. After 1 hour, adjust it to 0.5kg / min until the addition is complete;

[0052] Then the temperature was lowered to normal temperature and pressure, 0.1 part of pH regulator sodium bicarbonate was added, and the mixture was filtered and discharged.

[0053] Example 2

[0054] The vinyl acetate-ethylene copolymer emulsion is prepared by using the following raw materials in accordance with the following steps:

[0055] A. Raw material preparation

[0056] Prepare the initiator system solution: add 2.5 parts of deionized water, 0.04 parts of tert-butyl hydroperoxide and 0.08 parts of di-tert-butyl peroxide to the oxidant tank, stir to dissolve, and obtain the oxidant solution; add 2.5 parts of deionized water and 0.15 parts of sodium isoascorbate to the reducing agent tank, stir to dissolve, and obtain the reducing agent solution;

[0057] Preparation of protective colloid solution: under stirring, add 22 parts of deionized water, 0.5 parts of PVA0888, and 2.5 parts of PVA1788 in the dissolution tank in sequence and stir evenly, then heat to 90°C and keep at this temperature for 100 minutes, then cool to 60°C for use;

[0058] B. Feed production

[0059] Add 0.2 parts of emulsifier 15s-40, 18 parts of deionized water and the prepared protective colloid solution into the reactor, stir evenly, add 30 parts of vinyl acetate, increase the temperature and introduce ethylene to increase the pressure;

[0060] When the temperature rises to 50°C and the pressure reaches 2.5MPa, start adding the oxidant solution and the reducing agent solution at a rate of 0.1kg / min. When the temperature in the kettle reaches 58°C, stop adding the oxidant solution and the reducing agent solution. After maintaining for 22 minutes, continue adding the oxidant solution and the reducing agent solution at a rate of 0.02kg / min.

[0061] When the temperature rises to 74°C and the pressure reaches 5.0MPa, 16 parts of vinyl acetate are added at a uniform rate within 70 minutes, and the temperature of the reactor is controlled at 78°C. After the addition of vinyl acetate is completed, the ethylene is turned off, and the addition rate of the remaining oxidant solution and reductant solution is controlled at 0.03kg / min, and adjusted to 0.4kg / min after 1 hour until the addition is completed;

[0062] Then the temperature was lowered to normal temperature and pressure, 0.1 part of pH adjuster sodium acetate was added, and the mixture was filtered and discharged.

[0063] Example 3

[0064] The vinyl acetate-ethylene copolymer emulsion is prepared by using the following raw materials in accordance with the following steps:

[0065] A. Raw material preparation

[0066] Prepare the initiator system solution: add 4 parts of deionized water and 0.11 parts of di-tert-butyl peroxide to the oxidant tank, stir to dissolve, and obtain the oxidant solution; add 4 parts of deionized water and 0.14 parts of ascorbic acid to the reducing agent tank, stir to dissolve, and obtain the reducing agent solution;

[0067] Preparation of protective colloid solution: under stirring, add 18 parts of deionized water, 1.5 parts of PVA0888, and 2.7 parts of PVA1888 in the dissolution tank in sequence and stir evenly, then heat to 90°C and keep at this temperature for 100 minutes, then cool to 50°C for use;

[0068] B. Feed production

[0069] Add 0.2 parts of emulsifier X-100, 19 parts of deionized water and the prepared protective colloid solution into the reactor, stir evenly, add 42 parts of vinyl acetate, increase the temperature and introduce ethylene to increase the pressure;

[0070] When the temperature rises to 53°C and the pressure reaches 2.5MPa, start adding the oxidant solution and the reducing agent solution at a rate of 0.5kg / min. When the temperature in the kettle reaches 62°C, stop adding the oxidant solution and the reducing agent solution. After maintaining for 25 minutes, continue adding the oxidant solution and the reducing agent solution at a rate of 0.03kg / min.

[0071] When the temperature rises to 72°C and the pressure reaches 5.0MPa, add 20 parts of vinyl acetate at a uniform rate within 65 minutes, and control the temperature of the reactor to be 76°C. After the addition of vinyl acetate, turn off the ethylene, and control the addition rate of the remaining oxidant solution and reductant solution at 0.05kg / min. After 1 hour, adjust it to 0.5kg / min until the addition is complete;

[0072] Then the temperature was lowered to normal temperature and pressure, 0.2 parts of pH regulator sodium acetate was added, and the mixture was filtered and discharged.

[0073] Example 4

[0074] The vinyl acetate-ethylene copolymer emulsion is prepared by using the following raw materials in accordance with the following steps:

[0075] A. Raw material preparation

[0076] Prepare the initiating system solution: add 3.5 parts of deionized water and 0.04 parts of tert-butyl perbenzoate, 0.04 parts of tert-butyl hydroperoxide, and 0.08 parts of di-tert-butyl peroxide to the oxidant tank, stir to dissolve, and obtain the oxidant solution; add 3.5 parts of deionized water and 0.2 parts of ascorbic acid to the reducing agent tank, stir to dissolve, and obtain the reducing agent solution;

[0077] Preparation of protective colloid solution: under stirring, add 21 parts of deionized water, 2 parts of PVA0588, and 2.5 parts of PVA2088 in the dissolution tank in sequence and stir evenly, then heat to 90°C and keep at this temperature for 100 minutes, then cool to 50°C for use;

[0078] B. Feed production

[0079] Add 0.15 parts of emulsifier CA90, 16 parts of deionized water and the prepared protective colloid solution into the reactor, stir evenly, add 40 parts of vinyl acetate, increase the temperature and introduce ethylene to increase the pressure;

[0080] When the temperature rises to 48°C and the pressure reaches 2.5MPa, start adding the oxidant solution and the reducing agent solution at a rate of 0.4kg / min. When the temperature in the kettle reaches 60°C, stop adding the oxidant solution and the reducing agent solution. After maintaining for 20 minutes, continue adding the oxidant solution and the reducing agent solution at a rate of 0.02kg / min.

[0081] When the temperature rises to 74°C and the pressure reaches 4.6MPa, 16 parts of vinyl acetate are added at a uniform rate within 75 minutes, and the temperature of the reactor is controlled at 76°C. After the addition of vinyl acetate is completed, the ethylene is turned off, and the addition rate of the remaining oxidant solution and reductant solution is controlled at 0.02kg / min, and adjusted to 0.3kg / min after 1 hour until the addition is completed;

[0082] Then the temperature was lowered to normal temperature and pressure, 0.15 parts of pH regulator sodium bicarbonate was added, and the mixture was filtered and discharged.

[0083] Comparative Example 1

[0084] Except that hydrogen peroxide is used as the oxidant, other parameter settings are the same as those in Example 1.

[0085] Comparative Example 2

[0086] Except that when the temperature in the kettle reached 62° C., the addition of the oxidant solution and the reducing agent solution was not stopped but continued at a feed rate of 0.01 kg / min. Other parameter settings were the same as those in Example 1.

[0087] Performance Testing

[0088] The particle size distribution and dilution stability of the vinyl acetate-ethylene copolymer emulsions prepared in Examples 1-4 and Comparative Examples 1-2 were tested. The results are as follows: Figure 1-6 As shown in Table 1;

[0089] Among them, the particle size distribution was tested using a MASTERSIZER 2000 laser particle size analyzer;

[0090] The dilution stability test method is as follows: the sample is diluted with distilled water to a non-volatile content of 3.0% wt, and then the aqueous dispersion is placed in a 100mL stoppered measuring cylinder. After standing for 72 hours, the volume of the upper clear liquid and the volume of the bottom precipitate are measured. The dilution stability is expressed as the volume fraction of the bottom precipitate in 100mL of the dilution solution. The result is rounded to an integer, and the smaller the value, the better the dilution stability.

[0091] Table 1 Performance test results

[0092] Test items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Dilution stability / % 1.5 1.6 1.5 1.3 2.5 2.8 Volume average particle size / μm 0.739 0.750 0.777 0.814 0.731 0.735

[0093] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a vinyl acetate-ethylene copolymer emulsion, which is prepared from raw materials including monomers, an initiator system, an emulsifier system and a pH regulator, wherein the initiator system includes an oil-soluble oxidant, and is characterized in that: The oil-soluble oxidant is added in a stepwise manner, specifically: When the temperature rises to 48-53°C and the pressure reaches 2.0-3.0MPa, start adding the oxidant solution and the reducing agent solution of the initiation system at a rate of 0.1-0.5kg / min. When the temperature in the kettle reaches 58-62°C, stop adding the oxidant solution and the reducing agent solution. After maintaining for 20-25min, add the oxidant solution and the reducing agent solution at a feeding rate of 0.01-0.03kg / min. When the temperature rises to 70-74°C and the pressure reaches 4.0-5.0MPa, add the remaining vinyl acetate within 60-80min, and control the temperature of the reactor to 75-78°C. After the addition of vinyl acetate, turn off ethylene, and control the feeding rate of the remaining oxidant solution and the reducing agent solution to 0.02-0.06kg / min. After 1h, adjust it to 0.1-0.5kg / min until the addition is complete; The oil-soluble oxidant is selected from one or more of tert-butyl perbenzoate, tert-butyl hydroperoxide and di-tert-butyl peroxide.

2. The preparation method according to claim 1, characterized in that: The oil-soluble oxidant is a combination of tert-butyl perbenzoate and tert-butyl hydroperoxide.

3. The preparation method according to claim 2, characterized in that: The mass ratio of tert-butyl perbenzoate to tert-butyl hydroperoxide is 3:3.5-3:

7.

4. The preparation method according to claim 3, characterized in that: The mass ratio of tert-butyl perbenzoate to tert-butyl hydroperoxide is 3:

5.

5. The preparation method according to claim 1, characterized in that: The oil-soluble oxidant is a composition of tert-butyl perbenzoate, tert-butyl hydroperoxide and di-tert-butyl peroxide.

6. The preparation method according to claim 5, characterized in that: The mass ratio of tert-butyl perbenzoate, tert-butyl hydroperoxide and di-tert-butyl peroxide is 1:0.5-2:1.5-3.

7. The preparation method according to claim 6, characterized in that: The mass ratio of tert-butyl perbenzoate, tert-butyl hydroperoxide and di-tert-butyl peroxide is 1:1:2.

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