Vinyl acetate-ethylene copolymer emulsion and preparation method thereof

Abstract

The present invention belongs to the technical field of vinyl acetate polymers, and specifically relates to a vinyl acetate-ethylene copolymer emulsion. The contact angle of the emulsion is 55-65°. The present invention improves the bonding performance of the emulsion to the bonding material; significantly increases the ethylene content of the vinyl acetate-ethylene copolymer emulsion, and is used for redispersible latex powder, which can significantly improve the flexibility and anti-freeze cracking performance of the mortar.

Description

Technical Field

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

[0002] In order to overcome the poor performance of polyvinyl acetate in water resistance, acid resistance, alkali resistance, aging resistance, etc., people developed vinyl acetate-ethylene copolymer emulsion (abbreviated as EVA emulsion or VAE emulsion) products in the 1960s. The introduction of ethylene segments weakens the interaction within and between molecular chains and increases the activity of molecular chains, that is, it plays an internal plasticizing role, and this internal plasticizing role is permanent, and there is no migration, volatilization, exudation and other phenomena caused by low molecular weight plasticizers ("Progress in EVA Emulsion", Li Jianzong, Adhesives, Issue 4, 1991, Page 29, Left Column, First Paragraph, Lines 1-8, Publication Date December 31, 1991; "New VAE Emulsion and Its Application in Adhesives", Liu Bingpo et al., China Adhesives, Volume 14, Issue 7, 2005, Page 24, Left Column, First Paragraph, Line 1, Publication Date July 31, 2005).

[0003] Vinyl acetate-ethylene copolymer emulsion is a copolymer of ethylene and vinyl acetate with the participation of auxiliary materials. It has the advantages of low film-forming temperature, excellent mechanical properties, excellent storage stability, etc. It is non-toxic and tasteless, and has good bonding effect on the surface of various materials. It has been widely used in adhesives, leather processing, construction, tobacco, laminating adhesives, composite materials, packaging, textiles, wood processing, coatings, carpets, paper processing, non-woven fabrics and other fields ("EVA Emulsion Production Process and Market Analysis", Guo Xiao et al., Engineering Technology, Vol. 3, 2007, No. Page 242, left column, first paragraph, line 1 to second paragraph, line 6, published on December 31, 2007; “Application and Modification Research Progress of EVA Emulsion”, Luo Shi et al., Leather Science and Engineering, 2006, Vol. 16, No. 6, page 51, right column, first paragraph, lines 1-3, published on December 31, 2006; “EVA Emulsion Production Technology and Market Analysis”, Chen Zhaoyan et al., Liaoning Chemical Industry, 2008, Vol. 37, No. 6, page 405, right column, third paragraph, lines 1-5, published on June 30, 2008).

[0004] However, the existing vinyl acetate-ethylene copolymer emulsion has poor bonding performance for difficult-to-bond materials. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a vinyl acetate-ethylene copolymer emulsion having excellent bonding performance to difficult-to-bond materials.

[0006] Unless otherwise specified, the parts described in the present invention are parts by mass.

[0007] Vinyl acetate-ethylene copolymer emulsion has a contact angle of 55-65°.

[0008] Furthermore, the contact angle of the vinyl acetate-ethylene copolymer emulsion is 58-62°

[0009] The present invention also aims to protect the preparation method of vinyl acetate-ethylene copolymer emulsion, which is prepared from raw materials including emulsifier, and the amount of emulsifier is 10‰-15‰ of the total mass of the raw materials.

[0010] Preferably, the amount of emulsifier used is 10‰ of the total mass of the raw materials.

[0011] Preferably, the emulsifier comprises a nonionic emulsifier with an ethylene oxide addition number EO≥40.

[0012] Preferably, the nonionic emulsifier includes one or more of fatty alcohol polyoxyethylene ethers with an ethylene oxide addition number EO of 40-60 and alkylphenol polyoxyethylene ethers with an ethylene oxide addition number EO of 40-60.

[0013] Preferably, the raw material also includes polyvinyl alcohol.

[0014] Preferably, the polyvinyl alcohol comprises one or more polyvinyl alcohols having a degree of polymerization of 500-1800 and a degree of alcoholysis of 86 mol%-92 mol%.

[0015] Preferably, the polyvinyl alcohol comprises a combination of polyvinyl alcohol having a degree of polymerization of 500-800 and polyvinyl alcohol having a degree of polymerization of 1000-1800.

[0016] Preferably, the mass ratio of polyvinyl alcohol with a degree of polymerization of 500-800 to polyvinyl alcohol with a degree of polymerization of 1000-1800 is 6-7:3-4.

[0017] Preferably, the mass ratio of polyvinyl alcohol with a degree of polymerization of 500-800 to polyvinyl alcohol with a degree of polymerization of 1000-1800 is 7:3.

[0018] The purpose of the present invention is also to protect the use of the vinyl acetate-ethylene copolymer emulsion in redispersible latex powder. The beneficial effects of the present invention are:

[0019] The invention significantly improves the bonding performance of the emulsion to the bonding material.

[0020] The invention significantly increases the ethylene content of vinyl acetate-ethylene copolymer emulsion.

[0021] The vinyl acetate-ethylene copolymer emulsion of the invention has a high ethylene content and is used for redispersible latex powder, and can significantly improve the flexibility and frost crack resistance of mortar. DETAILED DESCRIPTION

[0022] 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.

[0023] Example 1

[0024] The vinyl acetate-ethylene copolymer emulsion is prepared by using the following raw materials in accordance with the following steps:

[0025] A. Raw material preparation

[0026] Add 0.1 parts of tert-butyl hydroperoxide and 3 parts of deionized water into tank A and stir to dissolve to obtain an oxidant solution;

[0027] Add 0.2 parts of ascorbic acid and 3 parts of deionized water into tank B and stir to dissolve to obtain a reducing agent solution;

[0028] Add 1.4 parts of PVA0588, 0.6 parts of PVA1792 and 10 parts of deionized water into tank C, heat and stir to dissolve, and obtain a protective colloid solution;

[0029] Mix 0.1 parts of zinc acetate and 2 parts of deionized water to obtain a pH regulator solution;

[0030] B. Feed production

[0031] Add 1 part of emulsifier 15S-40 (EO number is 40), prepared pH adjusting agent solution, 20 parts of deionized water and prepared protective colloid solution into the reactor, stir evenly, add 5.5 parts of vinyl acetate, increase the temperature and introduce ethylene to increase the pressure;

[0032] When the temperature rises to 52°C and the pressure reaches 4.5MPa, start adding the oxidant solution and the reducing agent solution at a rate of 0.03kg / min. When the temperature in the reactor reaches 78°C and the ethylene pressure rises to 7.5MPa, add 49.5 parts of vinyl acetate at a uniform rate within 210min. The feeding rate of the oxidant solution and the reducing agent solution is adjusted to 0.1kg / min, and the temperature of the reactor is controlled at 85°C.

[0033] After the addition of vinyl acetate is complete, turn off the ethylene, and control the addition rate of the remaining oxidant solution and reductant solution at 0.2 kg / min, and adjust it to 1 kg / min after 30 minutes until the addition is complete;

[0034] Then it is cooled to normal temperature and pressure, filtered and discharged.

[0035] Example 2

[0036] The vinyl acetate-ethylene copolymer emulsion is prepared by using the following raw materials in accordance with the following steps:

[0037] A. Raw material preparation

[0038] Add 0.2 parts of di-tert-butyl peroxide and 4 parts of deionized water into tank A and stir to dissolve to obtain an oxidant solution;

[0039] Add 0.2 parts of ascorbic acid and 4 parts of deionized water into tank B and stir to dissolve to obtain a reducing agent solution;

[0040] 2.1 parts of PVA0588, 0.9 parts of PVA1788 and 10 parts of deionized water were added to tank C, and the mixture was heated and stirred to dissolve.

[0041] obtaining a protective colloid solution;

[0042] Mix 0.2 parts of sodium acetate and 3 parts of deionized water to obtain a pH regulator solution;

[0043] B. Feed production

[0044] Add 1.0 part of emulsifier TO-40 (EO number is 40), 0.5 part of emulsifier TX-50 (EO number is 50), the prepared pH adjusting agent solution, 24 parts of deionized water and the prepared protective colloid solution into the reactor, stir evenly, add 17.4 parts of vinyl acetate, increase the temperature and introduce ethylene to increase the pressure;

[0045] When the temperature rises to 54°C and the pressure reaches 5.5MPa, start adding the oxidant solution and the reducing agent solution at a rate of 0.04kg / min. When the temperature in the reactor reaches 75°C and the ethylene pressure rises to 8.0MPa, add 40.6 parts of vinyl acetate evenly within 180min. The feeding rate of the oxidant solution and the reducing agent solution is adjusted to 0.15kg / min, and the temperature of the reactor is controlled at 83°C.

[0046] After the addition of vinyl acetate is complete, turn off the ethylene, and control the addition rate of the remaining oxidant solution and reductant solution at 0.3 kg / min. After 30 minutes, adjust it to 3 kg / min until the addition is complete.

[0047] Then it is cooled to normal temperature and pressure, filtered and discharged.

[0048] Example 3

[0049] The vinyl acetate-ethylene copolymer emulsion is prepared by using the following raw materials in accordance with the following steps:

[0050] A. Raw material preparation

[0051] Add 0.15 parts of di-tert-butyl peroxide and 5 parts of deionized water into tank A and stir to dissolve to obtain an oxidant solution;

[0052] Add 0.2 parts of sodium isoascorbate and 5 parts of deionized water into tank B and stir to dissolve to obtain a reducing agent solution;

[0053] Add 1.75 parts of PVA0588, 0.3 parts of PVA1388, 0.45 parts of PVA1788 and 10 parts of deionized water into tank C, heat and stir to dissolve, and obtain a protective colloid solution;

[0054] Mix 0.2 parts of sodium acetate and 2 parts of deionized water to obtain a pH regulator solution;

[0055] B. Feed production

[0056] Add 1.2 parts of emulsifier NP-50 (EO number is 50), the prepared pH adjusting agent solution, 18 parts of deionized water and the prepared protective colloid solution into the reactor, stir evenly, add 11 parts of vinyl acetate, increase the temperature and introduce ethylene to increase the pressure;

[0057] When the temperature rises to 55°C and the pressure reaches 4.9MPa, start adding the oxidant solution and the reducing agent solution at a rate of 0.05kg / min. When the temperature in the kettle reaches 76°C and the ethylene pressure rises to 8.5MPa, add 44 parts of vinyl acetate at a uniform rate within 200min. The feeding rate of the oxidant solution and the reducing agent solution is adjusted to 0.15kg / min, and the temperature of the reactor is controlled at 86°C.

[0058] After the addition of vinyl acetate is complete, turn off the ethylene, and control the addition rate of the remaining oxidant solution and reductant solution at 0.2 kg / min. After 30 minutes, adjust it to 3 kg / min until the addition is complete.

[0059] Then it is cooled to normal temperature and pressure, filtered and discharged.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 1 is that the amount of emulsifier 15S-40 used is 0.3 parts.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 1 is that the emulsifier used is 15S-9 (EO number is 9).

[0064] Performance Testing

[0065] The ethylene content, contact angle and T-peel strength of the vinyl acetate-ethylene copolymer emulsions prepared in Examples 1-4 and Comparative Examples 1-2 were tested, and the results are shown in Table 1;

[0066] Among them, the ethylene content is tested in accordance with "GB / T27573-2011 Vinyl acetate-ethylene copolymer emulsion";

[0067] The contact angle was measured using a video contact angle meter DSA100 from KRUSS, Germany.

[0068] The T-peel strength is measured according to GB / T2791-1995 Adhesive T-peel strength test method - Flexible material to flexible material.

[0069] Table 1 Performance test results

[0070] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Ethylene content / wt% 25.1 25.2 26.5 20.3 18.8 Contact angle / ° 61.36 59.42 58.27 72.32 70.96 T-peel strength / (KN / m) 1.453 1.378 1.431 0.891 0.762

[0071] 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. Vinyl acetate-ethylene copolymer emulsion, characterized in that: The contact angle measured by the video contact angle meter DSA100 is 55-65°; the emulsifier used in the preparation method of the copolymer emulsion is one or more of fatty alcohol polyoxyethylene ether with an ethylene oxide addition number EO of 40-60 and alkylphenol polyoxyethylene ether with an ethylene oxide addition number EO of 40-60.

2. The vinyl acetate-ethylene copolymer emulsion according to claim 1, characterized in that: The contact angle is 58-62°.

3. The method for preparing the vinyl acetate-ethylene copolymer emulsion according to claim 1 or 2, characterized in that: The amount of the emulsifier used is 10‰-15‰ of the total mass of the raw materials.

4. The preparation method according to claim 3, characterized in that: The raw materials also include polyvinyl alcohol.

5. The preparation method according to claim 4, characterized in that: The polyvinyl alcohol includes one or more polyvinyl alcohols having a degree of polymerization of 500-1800 and a degree of alcoholysis of 86 mol %-92 mol %.

6. The preparation method according to claim 5, characterized in that: The polyvinyl alcohol comprises a combination of polyvinyl alcohol having a polymerization degree of 500-800 and polyvinyl alcohol having a polymerization degree of 1000-1800.

7. The preparation method according to claim 6, characterized in that: The mass ratio of polyvinyl alcohol with a polymerization degree of 500-800 to polyvinyl alcohol with a polymerization degree of 1000-1800 is 6-7:3-4.

8. Use of the vinyl acetate-ethylene copolymer emulsion according to claim 1 or 2 in redispersible latex powder.