Anti-sagging VAE emulsion and preparation method thereof

Abstract

The present invention belongs to the technical field of vinyl acetate polymers, and specifically relates to an anti-sagging VAE emulsion, which is obtained by copolymerizing monomers including ethylene and vinyl acetate, and the monomers also include acrylic acid and isocetyl acrylate. The present invention can increase the water addition ratio in the polymer cement waterproof emulsion to 20% without affecting the anti-sagging performance.

Description

Technical Field

[0001] The invention belongs to the technical field of vinyl acetate polymers, and in particular relates to an anti-sagging VAE emulsion and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of urban infrastructure construction and residential construction, the demand for underground engineering waterproof coatings has increased dramatically. In this context, polymer cement waterproof emulsion came into being ("Development and Application of Polymer Cement Waterproof Coatings", Zhang Hongwei, Underground Engineering and Tunnels, 2003 No. B1, page 102, left column, first paragraph, lines 14-25, published on December 31, 2003).

[0003] Polymer cement waterproof coating, referred to as JS waterproof coating, is a two-component water-based building waterproof coating composed of polymer emulsion and cement inorganic material as the main raw materials. Polymer cement waterproof coating has the advantages of high elasticity, high strength, good durability, strong toughness, easy adhesion to moist base, etc., and can adjust flexibility and strength according to the requirements of different construction sites. It is easy to construct and is suitable for roofs, toilets and bathrooms, underground buildings, ground buildings, etc. ("Development and Application of Polymer Cement Waterproof Coating", Zhang Hongwei, Underground Engineering and Tunnels, 2003 No. B1, page 102, left column, paragraph 2, lines 1-8, published on December 31, 2003; "Overview of the Development of Polymer Cement Waterproof Coating", Wang Zhi et al., New Building Coatings, 2009 Vol. 36 No. 10, page 79, left column, paragraph 1, lines 1-6, published on December 31, 2009).

[0004] Polymer emulsion is the film-forming substance of polymer cement waterproof coating, which has a crucial influence on the durability, elongation, strength and other indicators of the coating. Among the polymer emulsions used for polymer cement waterproof coating, vinyl acetate-ethylene copolymer (VAE emulsion for short) has a low glass transition temperature and good weather resistance due to the presence of ethylene segments; secondly, compared with acrylate emulsions, it has better creep resistance and low cost; thirdly, it has high strength when used as waterproof coating, so vinyl acetate-ethylene copolymer has received extensive attention in the field of polymer cement waterproof coating ("Development and Application Research of New Cement Waterproof VAE", Cao Yong, Adhesion, Vol. 31, No. 7, 2010, p. 44, left column, first paragraph, lines 1-9, published on December 31, 2010).

[0005] However, the polymer cement waterproof coating made from the existing vinyl acetate-ethylene copolymer emulsion has poor anti-sagging performance and cannot be hung on the vertical facade.

[0006] To solve the above problems, the inventor team developed an ethylene-vinyl acetate copolymer, which is obtained by copolymerizing monomers including ethylene and vinyl acetate, and the monomers also include acrylic acid and acrylic ester.

[0007] However, when using this polymer cement waterproof emulsion, the maximum water addition ratio is 10% to achieve better anti-sagging performance. Summary of the invention

[0008] In view of this, an object of the present invention is to provide a vinyl acetate-ethylene copolymer.

[0009] To achieve the above object, the technical solution of the present invention is:

[0010] Vinyl acetate-ethylene copolymer is obtained by copolymerizing monomers including ethylene and vinyl acetate, and the monomers also include acrylic acid and isooctyl acrylate.

[0011] Furthermore, the monomers include, by weight, 40-42 parts of vinyl acetate, 0.4-0.6 parts of acrylic acid, 0.7-0.9 parts of isooctyl acrylate and an appropriate amount of ethylene.

[0012] Furthermore, the raw materials for preparing the vinyl acetate-ethylene copolymer also include an emulsifying system, a redox system, a pH regulator and a post-processing aid.

[0013] Furthermore, the emulsification system includes a protective colloid and an emulsifier.

[0014] Furthermore, the protective colloid is polyvinyl alcohol.

[0015] Furthermore, the emulsifier is octylphenol polyoxyethylene ether or nonylphenol polyoxyethylene ether or fatty alcohol polyoxyethylene ether.

[0016] Furthermore, the mass ratio of the protective colloid to the emulsifier is 2.5-2.7:0.3-0.7.

[0017] Furthermore, the redox system comprises an oxidant and a reductant.

[0018] Furthermore, the reducing agent is formaldehyde sulfoxylate, ascorbate or tartrate.

[0019] Furthermore, the oxidant is hydrogen peroxide, potassium persulfate, or ammonium persulfate.

[0020] Furthermore, the mass ratio of the oxidant to the reducing agent is 0.2-0.4:0.1-0.3.

[0021] Furthermore, the pH adjuster is formic acid, bicarbonate, acetate, or phosphate.

[0022] Furthermore, the post-treatment aid comprises a post-treatment oxidant and a post-treatment reductant, and the oxidant and the reductant are as described above.

[0023] Furthermore, the preparation raw materials include, by weight, 40-42 parts of vinyl acetate, 0.4-0.6 parts of acrylic acid, 0.7-0.9 parts of isooctyl acrylate, an appropriate amount of ethylene, 2.8-3.4 parts of an emulsifying system, 0.3-0.7 parts of a redox system, 0.04-0.06 parts of a pH regulator, and 0.02-0.04 parts of a post-processing aid.

[0024] The present invention also aims to protect the method for preparing the vinyl acetate-ethylene copolymer, characterized in that, except for the ethylene monomer, the monomers are divided into primary monomers, secondary monomers and tertiary monomers and added to the reaction kettle three times;

[0025] Among them, the initial monomer is vinyl acetate accounting for 25%-35% of the total amount;

[0026] The secondary monomer is vinyl acetate, which accounts for 55%-60% of the total;

[0027] The tertiary monomers consist of acrylic acid, acrylic esters, and residual vinyl acetate;

[0028] Ethylene monomer was introduced after the initial monomer addition until the polymerization reaction was completed.

[0029] Furthermore, the addition rate of the tertiary monomer is 2.5-5 times the addition rate of the secondary monomer.

[0030] The present invention also aims at protecting a polymer cement waterproof coating, comprising a vinyl acetate-ethylene copolymer obtained by copolymerizing monomers including ethylene and vinyl acetate, and the monomers also include acrylic acid and isooctyl acrylate.

[0031] The beneficial effects of the present invention are:

[0032] The present invention can increase the water addition ratio in the polymer cement waterproof emulsion to 20% without affecting the anti-sagging performance.

[0033] The present invention increases the water addition ratio in the polymer cement waterproof emulsion to 20%, thereby reducing the production cost.

[0034] The preparation method of the invention is simple, the raw materials are easily available, no special equipment is required, the industrial implementation is convenient, and the application prospect is broad. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The anti-sagging performance test results of the polymer cement waterproof emulsion obtained by compounding the vinyl acetate-ethylene copolymer prepared in Example 1;

[0036] Figure 2 The anti-sagging performance test results of the polymer cement waterproof emulsion obtained by compounding the vinyl acetate-ethylene copolymer prepared in Example 2;

[0037] Figure 3 These are the test results of the anti-sagging performance of the polymer cement waterproof emulsion prepared by compounding the vinyl acetate-ethylene copolymer prepared in Comparative Example 1. DETAILED DESCRIPTION

[0038] 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.

[0039] Example 1

[0040] Vinyl acetate-ethylene copolymer, the specific preparation steps are:

[0041] A. Raw material preparation

[0042] 1) Prepare the oxidant solution system: add 3 parts of deionized water to 0.3 parts of hydrogen peroxide tank and stir to dissolve;

[0043] 2) Prepare reducing agent solution system: add 3 parts of deionized water to 0.2 parts of potassium tartrate reducing agent tank and stir to dissolve;

[0044] 3) Tertiary monomer: Mix 6 parts of vinyl acetate, 0.5 parts of acrylic acid and 0.9 parts of isooctyl acrylate evenly;

[0045] 4) Preparation of post-treatment agent solution: 0.03 parts of tert-butyl hydroperoxide and 0.8 parts of deionized water, 0.02 parts of potassium tartrate and 0.8 parts of deionized water were mixed evenly to obtain post-treatment solution A and post-treatment solution B respectively;

[0046] 5) Preparation of pH adjuster solution: Mix 0.03 parts of sodium bicarbonate and 0.4 parts of deionized water;

[0047] B. Feed production

[0048] Add 46 parts of deionized water, 1.3 parts of PVA1788 and 1.1 parts of PVA0588 to the reactor, stir at room temperature for 15 minutes, heat to 85°C to dissolve the polyvinyl alcohol, then add 0.6 parts of octylphenol polyoxyethylene ether, 0.01 parts of formic acid and 12 parts of vinyl acetate as the initial monomer to the reactor, and add ethylene to the reactor. When the temperature reaches 54-62°C and the pressure reaches 3.50-3.65MPa, start adding the prepared oxidant solution and reductant solution, continue to heat to 68°C, clear and cool completely;

[0049] The reaction and initiator addition rate were then controlled by a computer, the reactor pressure continued to increase to 5.58-5.96 MPa, and 26 portions of secondary monomer vinyl acetate were continuously added dropwise, and the secondary monomer was added dropwise at a uniform rate for 43 minutes;

[0050] Switch the monomer feed tank, slowly add three monomers, the three monomers are dripped at a uniform speed for 33 minutes, and the initiator dripping rate is reduced;

[0051] After the three monomer additions are completed, the temperature reaches 75-78°C and the pressure reaches 1.50-1.52MPa, and the finishing period begins;

[0052] After degassing to the degassing tank, the prepared post-treatment solution A and post-treatment solution B are added from different tanks for post-treatment; after cooling, the prepared pH adjusting agent solution is added, and the material is discharged, filtered, and packaged.

[0053] Example 2

[0054] Except that the tertiary monomer is composed of 6 parts of vinyl acetate, 0.6 parts of acrylic acid and 0.8 parts of isooctyl acrylate, other parameter settings of this embodiment are the same as those of embodiment 1.

[0055] Comparative Example 1

[0056] Except that the tertiary monomer does not contain isooctyl acrylate, other parameter settings of this comparative example are the same as those of Example 1.

[0057] Performance Testing

[0058] The vinyl acetate-ethylene copolymers prepared in Examples 1-2 and Comparative Example 1 are compounded to obtain a polymer cement waterproof coating.

[0059] Then the anti-sagging performance of the polymer cement waterproof coating was tested. The results are as follows Figure 1-3 As shown;

[0060] Among them, the preparation method of polymer cement waterproof coating is:

[0061] Ethylene-vinyl acetate copolymer, water and 325 silicate cement were prepared into polymer cement waterproof coatings in a mass ratio of 10:2:10 (experimental groups 1-2 and control group 3, respectively). The anti-sagging performance of the polymer cement waterproof coatings was then tested. The results are as follows: Figure 1-3 As shown;

[0062] Among them, the test method of anti-sagging performance is: use a brush to apply the paint on the smooth facade glass plate, the coating thickness is about 3-5mm, after about 3 seconds, observe the speed and degree of the paint flowing down, and the beginning and end of the painted surface are not considered.

[0063] 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, which is obtained by copolymerizing monomers including ethylene and vinyl acetate, characterized in that: The monomers also include acrylic acid and isooctyl acrylate; in parts by mass, the monomers include 40-42 parts of vinyl acetate, 0.4-0.6 parts of acrylic acid, 0.7-0.9 parts of isooctyl acrylate and an appropriate amount of ethylene; Except for ethylene monomer, the monomers are divided into initial monomer, secondary monomer and tertiary monomer and added into the reaction kettle in three times; Among them, the initial monomer is vinyl acetate accounting for 25%-35% of the total amount; The secondary monomer is vinyl acetate, which accounts for 55%-60% of the total; The tertiary monomers consist of acrylic acid, isooctyl acrylate, and residual vinyl acetate; Ethylene monomer was introduced after the initial monomer addition until the polymerization reaction was completed.

2. The method for preparing a vinyl acetate-ethylene copolymer according to claim 1, characterized in that: The raw materials for preparing the vinyl acetate-ethylene copolymer also include an emulsifying system, a redox system, a pH regulator and a post-processing auxiliary agent.

3. The method for preparing a vinyl acetate-ethylene copolymer according to claim 2, characterized in that: The emulsification system comprises a protective colloid and an emulsifier.

4. The method for preparing a vinyl acetate-ethylene copolymer according to claim 3, characterized in that: The mass ratio of protective colloid to emulsifier is 2.5-2.7:0.3-0.

7.

5. The method for preparing a vinyl acetate-ethylene copolymer according to claim 2, characterized in that: The redox system includes an oxidizing agent and a reducing agent.

6. The method for preparing a vinyl acetate-ethylene copolymer according to claim 5, characterized in that: The mass ratio of the oxidant to the reductant is 0.2-0.4:0.1-0.

3.

7. The method for preparing a vinyl acetate-ethylene copolymer according to any one of claims 1 to 6, characterized in that: The raw materials include 40-42 parts of vinyl acetate, 0.4-0.6 parts of acrylic acid, 0.7-0.9 parts of isooctyl acrylate, an appropriate amount of ethylene, 2.8-3.4 parts of an emulsifying system, 0.3-0.7 parts of a redox system, 0.04-0.06 parts of a pH regulator and 0.02-0.04 parts of a post-processing aid, in parts by mass.

8. Vinyl acetate-ethylene copolymer prepared by the method for preparing vinyl acetate-ethylene copolymer according to any one of claims 1 to 7.

9. A polymer cement waterproof coating comprising the vinyl acetate-ethylene copolymer according to claim 8.

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