Polyethylene-vinyl acetate emulsion for compounding textiles and preparation method of polyethylene-vinyl acetate emulsion

Abstract

The invention discloses a polyethylene-vinyl acetate emulsion for textile compounding, which is characterized in that the grafting rate is 25-35%, the shearing rate is 1000s <-1 >, and the n value is 0.7-0.8, and the invention also discloses a preparation method and application of the polyethylene-vinyl acetate emulsion. According to the polyethylene-vinyl acetate emulsion prepared by the invention, the grafting rate is 25-35%, and when the shearing rate is 1000s <-1 >, the n value is 0.7-0.8; therefore, the textile compounding machine is suitable for compounding textiles.

Description

Technical Field

[0001] The invention relates to an ethylene-vinyl acetate emulsion, in particular to a polyethylene-vinyl acetate emulsion for textile compounding and a preparation method thereof. Background Art

[0002] Polyethylene-vinyl acetate emulsion is a kind of vinyl copolymer produced by free radical polymerization in water phase with polyvinyl alcohol as protective colloid and ethylene and vinyl acetate as monomers. It has good adhesion and is widely used in the field of textile composite bonding. However, the performance of emulsions produced by different formulas and processes varies greatly. If the selection is inappropriate, it is very easy to cause glue throwing and coating leakage, resulting in product quality accidents.

[0003] Chinese patent document CN114426620A discloses a vinyl acetate-ethylene copolymer emulsion prepared from raw materials including monomers, surfactants, initiators, reducing agents and pH regulators, wherein the surfactants include protective colloids and emulsifiers with a cloud point of ≤80°C.

[0004] The vinyl acetate-ethylene copolymer emulsion produced by the prior art is very prone to glue throwing and coating leakage, and is not suitable for textile lamination. Summary of the invention

[0005] The invention aims to provide a polyethylene-vinyl acetate emulsion which can be used for textile compounding and can avoid the occurrence of glue throwing, coating leakage and the like.

[0006] On the one hand, the present invention provides a polyethylene-vinyl acetate emulsion for textile composite, wherein the grafting rate of the emulsion is 25-35%, and the rheological property is a shear rate of 1000s -1 When the flow index n value is 0.7-0.8.

[0007] In a second aspect, the present invention provides a method for preparing the polyethylene-vinyl acetate emulsion of the present invention, which further comprises preparing the emulsion from the following raw materials in parts by weight: based on 50-55 parts of vinyl acetate raw materials, including 7-10 parts of ethylene, 2.0-3.6 parts of polyvinyl alcohol, 0.1-0.2 parts of a reducing agent and 11-15 parts of an oxidizing agent; the reducing agent and the oxidizing agent added during the emulsion reaction each have three rates; wherein the rate of the initially added reducing agent is 2.92×10 -3 -4.77×10 -3 parts / min, and the oxidant rate is 7.89×10 -2 -9.54×10 -2 Servings / min.

[0008] Furthermore, the initially added reducing agent and oxidizing agent are added simultaneously, and the rates of changing the reducing agent and oxidizing agent for the other two times are also changed simultaneously.

[0009] Furthermore, the initially added reducing agent and oxidizing agent are added when the pressure is raised to 2.0-3.0 MPa and the temperature is raised to 50-60°C.

[0010] Furthermore, the reducing agent rate after the first adjustment is 7.31×10 -4 -1.43×10 -3 parts / min, the oxidant rate is 2.20×10 -2 -2.94×10 -2 Servings / min.

[0011] Furthermore, the first adjustment of the reducing agent and oxidizing agent rates is performed when the temperature is 75-85° C. and the pressure is 3.0-5.0 MPa while adding the remaining vinyl acetate; the initial amount of vinyl acetate added accounts for 45-55% of the total vinyl acetate content.

[0012] Furthermore, the reducing agent and the oxidizing agent after the second adjustment are added within 40-45 minutes.

[0013] Furthermore, the second adjustment of the reducing agent and oxidizing agent rates is performed after the remaining vinyl acetate is added.

[0014] Further, the method comprises the following steps: adding polyvinyl alcohol, water and vinyl acetate accounting for 45-55% of the total vinyl acetate content and stirring evenly, adding ethylene and increasing the pressure to 2.0-3.0 MPa, heating the temperature to 50-60°C, and heating the reducing agent at 2.92×10 -3 -4.77×10 -3 parts / min, oxidant at 7.89×10 -2 -9.54×10 -2 10 parts / min. When the temperature reaches 75-85°C and the pressure reaches 3.0-5.0 MPa in 0.25-0.5 hours, add the remaining vinyl acetate and adjust the reducing agent to 7.31×10 -4 -1.43×10 -3 parts / min and oxidant is 2.20×10 -2 -2.94×10 -2 After the remaining vinyl acetate has been added, the ethylene is cut off and the reducing agent and the oxidizing agent are adjusted to be added within 40-45 minutes.

[0015] In a third aspect, the present invention provides the use of the polyethylene-vinyl acetate emulsion of the present invention in textile compounding.

[0016] The present invention has the following beneficial effects: (1) The emulsion product of the present invention has good stability, a grafting rate of 25-35%, and a shear rate of 1000s -1 When the n value is 0.7-0.8, it will not cause glue throwing or missing coating when used in the field of textile composite bonding.

[0017] (2) The emulsion polymerization process of the present invention is easy to implement and convenient for industrial production.

[0018] (3) The emulsion of the present invention not only meets the technical requirements of "HJ2541-2016 Technical Requirements for Environmental Labeling Products - Adhesives", but also meets the requirements of clean production and is environmentally friendly. DETAILED DESCRIPTION

[0019] 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.

[0020] The "1 portion" described in the embodiments of the present invention means "1 g".

[0021] The polyvinyl alcohol used in the present invention is selected from polyvinyl alcohol with a polymerization degree of 501-2000 and an alcoholysis degree of 85-90% mol / mol.

[0022] The reducing agent of the present invention is ascorbic acid, and the oxidizing agent is hydrogen peroxide (3%wt).

[0023] The pH adjuster is bicarbonate.

[0024] The method for preparing the polyethylene-vinyl acetate emulsion of the present invention comprises the following steps: Add polyvinyl alcohol, then add 45-55% of the total vinyl acetate content of vinyl acetate, stir evenly, add ethylene to increase the pressure to 2.0-3.0MPa; when the temperature reaches 50-60℃, add the oxidant solution and the reducing agent at the same time, and the rate of adding the reducing agent is 2.92×10 -3 -4.77×10 -3 parts / min, and the rate of the oxidant is 7.89×10 -2 -9.54×10 -2 10 ... -4 -1.43×10 -3 parts / min and the rate of oxidant is 2.20×10-2 -2.94×10 -2 After the vinyl acetate is added in 1 hour, the ethylene is cut off and the remaining oxidant and reductant are controlled to drip in 40-45 minutes; after cooling, the mixture is degassed, filtered, cooled, and the pH adjusting agent solution is added and stirred evenly before discharging.

[0025] Detection method: For the test method of grafting rate, please refer to "Study on the Grafting Reaction of Protective Colloid and Monomer in Vinyl Acetate Emulsion Polymerization" (Gao Weibin. Guangxi University, 2004) Rheological test method: Rotational test, using plate / plate measuring rotor system PP50 (SN83388), temperature 25°C, gap 0.1mm, shear rate 0.1-10000s -1 The experimental results are expressed in the formula Fitting.

[0026] Example 1 The composition ratio of various raw materials is as follows (by weight fraction): 50 parts of vinyl acetate, 7 parts of ethylene, 2.0 parts of polyvinyl alcohol, 0.1 parts of reducing agent, 11 parts of oxidizing agent, 0.3 parts of pH adjusting agent, and 40 parts of deionized water; the polyvinyl alcohol is a mixture of 50% polyvinyl alcohol with a degree of polymerization of 1700 and a degree of alcoholysis of 88% mol / mol and 50% polyvinyl alcohol with a degree of polymerization of 501 and a degree of alcoholysis of 88% mol / mol; the oxidizing agent is hydrogen peroxide (3%wt); the reducing agent is ascorbic acid; and the pH adjusting agent is potassium bicarbonate.

[0027] The specific preparation steps of the polyethylene-vinyl acetate emulsion of the present invention are as follows: a. Preparation of raw materials 1) Prepare the oxidant solution system: add the oxidant to 4 parts of deionized water and stir to dissolve; 2) Prepare reducing agent solution system: add reducing agent to 4 parts of deionized water and stir to dissolve; 3) Dissolution of polyvinyl alcohol: weigh polyvinyl alcohol and 30 parts of water into a reactor, stir at room temperature for 15 minutes, and then heat to 80°C to dissolve for 30 minutes; 4) Prepare pH adjuster solution system: add pH adjuster to 2 parts of deionized water and stir to dissolve; b. Feed production Pump all the polyvinyl alcohol liquid and 10 parts of water into the reactor, then pump half of the vinyl acetate into the reactor, stir evenly, add ethylene to increase the pressure to the set pressure of 2.0MPa; heat the reactor, when the temperature rises to 50-60°C, add the oxidant solution and the reducing agent solution at the same time, the dropping rate is 0.12 parts / min, wait for 0.1 hour when the temperature in the reactor reaches 75°C and the pressure reaches 3.0MPa, uniformly add the remaining vinyl acetate (drip in 1 hour), and adjust the dropping rate of the oxidant solution and the reducing agent solution to 0.03 parts / min, the reaction temperature is controlled at 75°C by a heat exchanger, and after the vinyl acetate is added, cut off the ethylene; control the remaining oxidant solution and the reducing agent solution to drip in 45 minutes, cool to 60°C, degas, filter, cool, add the pH adjuster solution, stir evenly, and discharge.

[0028] The grafting rate of the tested product is 25%, and the shear rate is 1000s -1 When , the value of n is 0.7.

[0029] Example 2 The composition ratio of various raw materials is as follows (by weight fraction): 55 parts of vinyl acetate, 8.5 parts of ethylene, 3.3 parts of polyvinyl alcohol, 0.2 parts of reducing agent, 15 parts of oxidizing agent, 0.4 parts of pH adjusting agent, 45 parts of deionized water; the polyvinyl alcohol is a mixture of 50% polyvinyl alcohol with a degree of polymerization of 1700 and a degree of alcoholysis of 88% mol / mol and 50% polyvinyl alcohol with a degree of polymerization of 501 and a degree of alcoholysis of 88% mol / mol; the oxidizing agent is hydrogen peroxide (3%wt); the reducing agent is ascorbic acid; and the pH adjusting agent is sodium bicarbonate.

[0030] The specific preparation steps of the polyethylene-vinyl acetate emulsion of the present invention are as follows: a. Preparation of raw materials 1) Prepare the oxidant solution system: add the oxidant to 4 parts of deionized water and stir to dissolve; 2) Prepare reducing agent solution system: add reducing agent to 4 parts of deionized water and stir to dissolve; 3) Dissolution of polyvinyl alcohol: weigh polyvinyl alcohol and 35 parts of water into a reactor, stir at room temperature for 15 minutes, and then heat to 80°C to dissolve for 30 minutes; 4) Prepare pH adjuster solution system: add pH adjuster to 2 parts of deionized water and stir to dissolve; b. Feed production Pump all the polyvinyl alcohol liquid and 10 parts of water into the reactor, then pump half of the vinyl acetate into the reactor, stir evenly, add ethylene to increase the pressure to the set pressure of 3.0MPa; heat the reactor, and when the temperature rises to 60℃, add the oxidant solution and the reducing agent solution at the same time, with a drop rate of 0.1 part / min. After 10 minutes, when the temperature in the reactor reaches 85℃ and the pressure reaches 5.0MPa, add the remaining vinyl acetate at a uniform rate (drip in 1 hour), and adjust the oxidant solution and the reducing agent solution to drip at a rate of 0.03 part / min. The reaction temperature is cooled down by the heat exchanger and controlled at 85℃. After the vinyl acetate is added, cut off the ethylene; control the remaining oxidant solution and the reducing agent solution to drip in 45 minutes. Cool down to 60℃, degas, filter, cool, add the pH adjuster solution, stir evenly, and discharge.

[0031] The grafting rate of the tested product is 35%, and the shear rate is 1000s -1 When n is 0.8.

[0032] Example 3 In this embodiment, the initial dripping rate of the oxidant solution and the reducing agent solution is 0.13 parts / min. After 0.1 hour, when the temperature in the reactor reaches 85°C and the pressure reaches 5.0 MPa, the remaining vinyl acetate is dripped at a uniform rate (dripped in 1 hour), and the dripping rate of the oxidant solution and the reducing agent solution is adjusted to 0.04 parts / min, and the remaining oxidant solution and the reducing agent solution are controlled to drip in 45 minutes; the other reaction processes are the same as those in Example 1.

[0033] The grafting rate of the tested product is 33%, and the shear rate is 1000s -1 When , n value is 0.77.

[0034] Comparative Example 1 The initial dripping rate of the oxidant solution and the reducing agent solution in this comparative example is 0.03 parts / min, the first adjustment of the dripping rate of the oxidant solution and the reducing agent solution is 0.01 parts / min, and the remaining oxidant solution and the reducing agent solution are controlled to drip in 45 minutes; the other reaction processes are the same as those in Example 1.

[0035] The grafting rate of the tested product is 20% and the shear rate is 1000s -1 When n is 0.6.

[0036] It can be seen from the above Examples 1-3 and Comparative Example 1 that the specific means of controlling the specific addition rate of the initiating system during the reaction are adopted in Examples 1-3 of the present invention, while the specific addition rate of the present invention is not adopted in Comparative Example 1. The results obtained thereby show that the grafting rates of Examples 1-3 are 25-35%, and the shear rate is 1000s -1When n value is 0.7-0.8; in comparative example 1, the grafting rate is 20% and the shear rate is 1000s -1 When n is 0.6, it can be seen that the technical solution of controlling the specific addition rate of the initiating system during the reaction process can prevent the polyethylene-vinyl acetate emulsion from being thrown off or leaking, and is suitable for textile composites.

[0037] 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 polyethylene-vinyl acetate emulsion for textile composite, characterized in that: The grafting rate of the emulsion is 25-35%, and the rheological property is a shear rate of 1000s -1 When the flow index n value is 0.7-0.

8.

2. The method for preparing a polyethylene-vinyl acetate emulsion according to claim 1, characterized in that: The invention also includes preparing the emulsion from the following raw materials in parts by weight: based on 50-55 parts of vinyl acetate raw material, including 7-10 parts of ethylene, 2.0-3.6 parts of polyvinyl alcohol, 0.1-0.2 parts of reducing agent and 11-15 parts of oxidizing agent; the reducing agent and oxidizing agent added during the emulsion reaction have three rates respectively; the rate of the initially added reducing agent is 2.92×10 -3 -4.77×10 -3 parts / min, and the oxidant rate is 7.89×10 -2 -9.54×10 -2 Servings / min.

3. The method for preparing a polyethylene-vinyl acetate emulsion according to claim 2, characterized in that: The reducing agent and oxidizing agent initially added are added simultaneously, and the rates of changing the reducing agent and oxidizing agent for the other two times are also changed simultaneously.

4. The method for preparing the polyethylene-vinyl acetate emulsion according to claim 2 or 3, characterized in that: The initially added reducing agent and oxidizing agent are added when the pressure is raised to 2.0-3.0 MPa and the temperature is raised to 50-60°C.

5. The method for preparing the polyethylene-vinyl acetate emulsion according to any one of claims 2 to 4, characterized in that: The first adjusted reducing agent rate is 7.31×10 -4 -1.43×10 -3 parts / min, the oxidant rate is 2.20×10 -2 -2.94×10 -2 Servings / min.

6. The method for preparing the polyethylene-vinyl acetate emulsion according to claim 5, characterized in that: The first adjustment of the reducing agent and oxidizing agent rates is performed when the temperature is 75-85° C. and the pressure is 3.0-5.0 MPa while adding the remaining vinyl acetate; the initial amount of vinyl acetate added accounts for 45-55% of the total vinyl acetate content.

7. The method for preparing the polyethylene-vinyl acetate emulsion according to any one of claims 2 to 6, characterized in that: The reducing agent and oxidizing agent after the second adjustment are added in 40-45 minutes.

8. The method for preparing the polyethylene-vinyl acetate emulsion according to claim 7, characterized in that: The second adjustment of the reducing agent and oxidizing agent rates is performed after the addition of the remaining vinyl acetate is completed.

9. The method for preparing the polyethylene-vinyl acetate emulsion according to claim 2, characterized in that: The following steps are involved: Add polyvinyl alcohol, water and 45-55% of the total vinyl acetate content and stir evenly. Add ethylene to increase the pressure to 2.0-3.0 MPa. When the temperature is heated to 50-60 °C, the reducing agent is 2.92×10 -3 -4.77×10 -3 parts / min, oxidant at 7.89×10 -2 -9.54×10 -2 10 parts / min. When the temperature reaches 75-85°C and the pressure reaches 3.0-5.0 MPa in 0.25-0.5 hours, add the remaining vinyl acetate and adjust the reducing agent to 7.31×10 -4 -1.43×10 -3 parts / min and oxidant is 2.20×10 -2 -2.94×10 -2 After the remaining vinyl acetate has been added, the ethylene is cut off and the reducing agent and the oxidizing agent are adjusted to be added within 40-45 minutes.

10. Use of the polyethylene-vinyl acetate emulsion according to claim 1 in textile compounding.