A coagulant for producing nitrile gloves, its preparation method, and a nitrile glove

Abstract

The present invention discloses a coagulant for the production of nitrile gloves, which comprises calcium nitrate, polyvinyl alcohol, metal stearate, alkyl alcohol ethoxylate, and water. The coagulant of the present invention uses divalent metal cation calcium ion as a demulsifier, which has good demulsification effect and moderate demulsification speed, and can make the latex evenly distributed on the hand mold; uses alkyl alcohol ethoxylate and polyvinyl alcohol as wetting agents, which have good wetting effect, can significantly reduce the surface tension of the coagulant, increase the affinity between the coagulant and the hand mold, and improve the uniformity of the coagulant on the surface of the hand mold. The demulsifier and wetting agent used will not have any adverse effects on the adhesion of the gloves; uses metal stearate as an isolating agent, and the stearate root has good compatibility with the acrylonitrile chain segment and carboxyl group in the nitrile latex, ensuring a stable isolation effect between the nitrile glove and the hand mold, thereby improving the demouldability of the glove and reducing the stickiness of the glove.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a coagulant for producing nitrile gloves, a preparation method thereof, and a nitrile glove. Background Art

[0002] In the conventional coagulant for producing nitrile gloves, the lubricant is generally a single lubricant in which calcium stearates with different particle sizes are mutually matched. After the demoulding agent of the above single lubricant is used in the nitrile glove production line for a long time, with the continuous change of the particle size and dispersion state of calcium stearate in the coagulant tank, it is very difficult to ensure the lubricity and demoulding property of nitrile gloves.

[0003] If the demoulding property is poor, it will result in a large number of powder prints on the produced nitrile gloves, and serious adhesion will occur after the nitrile gloves are squeezed and placed for a long time, resulting in poor user experience.

[0004] Therefore, the coagulant used in the nitrile production line is one of the key factors in the production of nitrile gloves. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical defects and provide a coagulant for producing nitrile gloves, which has good glove demoulding property and ensures that nitrile gloves will not adhere even after long-term storage.

[0006] The present invention is achieved by the following technical solutions:

[0007] A coagulant for producing nitrile gloves, by weight percentage, comprises the following components:

[0008] Calcium nitrate 20 - 25%;

[0009] Polyvinyl alcohol 2 - 3%;

[0010] Metal stearate 3 - 5%;

[0011] Alkyl alcohol ethoxylate 1 - 2%;

[0012] Water 65 - 72%.

[0013] The degree of polymerization of polyvinyl alcohol can be 23,000 - 37,000. Preferably, the degree of polymerization of the polyvinyl alcohol ranges from 25,000 to 35,000.

[0014] The degree of polymerization of polyvinyl alcohol is measured by thermodynamic methods - the boiling point elevation method and the freezing point depression method. The degree of polymerization is preferably 25,000 - 35,000 because polyvinyl alcohol is the most stable and has the best wetting effect at this degree of polymerization under the temperature conditions (48 - 60°C) for the production of nitrile gloves.

[0015] Preferably, the particle size distribution range of the metal stearate is such that more than 90 wt% of the metal stearate has a particle size distribution between 6 and 17 microns. In this experiment, the particle size measurement method is the laser method, which measures the particle size by using the light scattering (diffraction) phenomenon of the particles. The range of 6 - 17 microns is preferred because this particle size has better compatibility with the glove surface. Specifically, it has been found through experiments that a particle size distribution of 35 - 90% is most conducive to glove demolding. If the proportion is too small, less than 35%, it is difficult for such a release agent to form an effective isolation layer on the hand mold and the glove fingertips; if the proportion is too high, large-area stretching powder marks are likely to appear, and the rejection rate of the gloves will increase.

[0016] More preferably, the particle size distribution range of the metal stearate is such that among the particle sizes between 6 and 17 microns, 35 - 90 wt% of the particle size range is between 6 and 11 microns. The particle size measurement method is the laser method, which measures the particle size by using the light scattering (diffraction) phenomenon of the particles. The range of 6 - 17 microns is preferred because this particle size has better compatibility with the glove surface.

[0017] The metal stearate is selected from at least one of calcium stearate, magnesium stearate, zinc stearate, and sodium stearate.

[0018] In the alkyl alcohol ethoxylate, the alkyl alcohol chain segment contains 11 - 19 carbon atoms; preferably, in the alkyl alcohol ethoxylate, the alkyl alcohol chain segment contains 12 - 14 carbon atoms.

[0019] A method for preparing a coagulant for producing nitrile gloves includes the following steps: preparing a dispersion of polyvinyl alcohol, alkyl alcohol ethoxylate, and water at 1500 - 1800 revolutions per minute for standby; mixing and dissolving water and calcium nitrate, then adding the above dispersion and metal stearate and stirring to mix evenly to obtain a coagulant for producing nitrile gloves.

[0020] The present invention has the following beneficial effects

[0021] The coagulant of the present invention uses divalent metal cation calcium ions as a demulsifier, which has good demulsification effect and moderate demulsification speed, and can make the latex evenly distributed on the hand mold; uses alkyl alcohol ethoxylate and polyvinyl alcohol as wetting agents, which have good wetting effects, can significantly reduce the surface tension of the coagulant, increase the affinity between the coagulant and the hand mold, and improve the uniformity of the coagulant on the hand mold surface. The demulsifier and wetting agent used will not have any adverse effects on the adhesion of the gloves; uses metal stearate as a release agent, and the stearate root has good compatibility with the acrylonitrile chain segment and carboxyl group in the nitrile latex, ensuring a stable isolation effect between the nitrile glove and the hand mold, thereby improving the demoldability of the glove and reducing the stickiness of the glove. Specific embodiments

[0022] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made. These all belong to the protection scope of the present invention.

[0023] The sources of the experimental raw materials used in the present invention are as follows:

[0024] Calcium nitrate: Shanxi Linfen Dyeing and Chemical Industry (Group) Co., Ltd.

[0025] Polyvinyl alcohol A: Degree of polymerization 23000, Shanghai Kayin Chemical Co., Ltd., 320A;

[0026] Polyvinyl alcohol B: Degree of polymerization 25600, Shanghai Kayin Chemical Co., Ltd., 300B;

[0027] Polyvinyl alcohol C: Degree of polymerization 34000, Shanghai Kayin Chemical Co., Ltd., 325B;

[0028] Polyvinyl alcohol D: Degree of polymerization 37000, Shanghai Kayin Chemical Co., Ltd., 310A;

[0029] Calcium stearate and zinc stearate are from commercially available products, and then raw materials with the designed particle size are obtained through mixing and screening.

[0030] Calcium stearate A: D90 = 4.8 μm, abbreviated as calcium A in Table 3;

[0031] Calcium stearate B: D90 = 6.2 μm, abbreviated as calcium B in Table 3;

[0032] Calcium stearate C: D90 = 10.7 μm, abbreviated as calcium C in Table 3;

[0033] Calcium stearate D: D90 = 12.1 μm, abbreviated as calcium D in Table 3;

[0034] Calcium stearate E: D90 = 16.9 μm, abbreviated as calcium E in Table 3;

[0035] Calcium stearate F: D90 = 18.4 μm, abbreviated as calcium F in Table 3;

[0036] Zinc stearate A: D90 = 6.3 μm, abbreviated as zinc A in Table 3;

[0037] Zinc stearate B: D90 = 12.4 μm, abbreviated as zinc B in Table 3;

[0038] Alkyl alcohol ethoxylate A: The alkyl alcohol chain segment contains 12 - 14 carbon atoms, from Shanghai Kayin Chemical Co., Ltd., C9 - 11 PARETH - 3;

[0039] Alkyl alcohol ethoxylate B: The alkyl alcohol segment contains 16 - 18 carbon atoms, sourced from Shanghai Kayin Chemical Co., Ltd., C9 - 11 PARETH - 6;

[0040] Preparation method of the coagulant for producing nitrile gloves in Examples and Comparative Examples: Prepare a dispersion by mixing polyvinyl alcohol, alkyl alcohol ethoxylate and water at 1500 - 1800 revolutions per minute for standby; Mix and dissolve water and calcium nitrate, then add the above dispersion and metal stearate and stir to mix evenly to obtain the coagulant for producing nitrile gloves.

[0041] Testing method:

[0042] Glove formula: By weight, 100 parts of nitrile latex, 1.0 part of sulfur, 1.5 parts of zinc oxide, 0.3 part of antioxidant, 1.5 parts of potassium hydroxide, 0.8 part of accelerator EZ / BZ, 1.7 parts of titanium dioxide.

[0043] Sample making method: Use the coagulants provided in Examples and Comparative Examples respectively, with a hand mold dipping time of 4 seconds and drying at 80°C for 2 min. When the temperature of the hand mold drops to 60°C, dip the hand mold in the glue for 3 seconds. After leaching, dry and vulcanize, with a vulcanization temperature of 120°C and a vulcanization time of 25 min. After vulcanization, wash with chlorine, clean, dry and demold.

[0044] (1) Make 20 gloves for each implementation plan, observe the demolding situation during sample making; Check the adhesion of the gloves after squeezing 20 gloves with a 1 kg iron block at room temperature for 6 hours, and the evaluation of the stickiness level of the gloves is shown in Table 1:

[0045] Table 1:

[0046] Degree Status Description Severe Adhesion The overall glove is caked, feels hard, and is difficult to separate Moderate Adhesion Part of the glove is caked, feels hard, and can be separated Slight Adhesion The overall glove is fluffy, slightly adhered, but can be separated one by one No Adhesion The overall glove is fluffy and can be separated one by one

[0047] The demolding property of the gloves is related to the above-mentioned stickiness. The more serious the above-mentioned stickiness is, the worse the demolding property is.

[0048] (2) Adhesion level after long-term storage: Stack the gloves in pairs, observe the adhesion of the gloves after squeezing and storing with a 1 kg iron block at room temperature for 30 days, as shown in Table 2:

[0049] Table 2:

[0050] Degree Status Description Severe Adhesion It is difficult to separate the gloves. Forcibly separating the gloves will cause them to tear Moderate Adhesion The gloves are adhered and can be separated by force Slight Adhesion Can be separated by gently pulling apart No Adhesion Almost no adhesion

[0051] Table 3: Coagulant formula and test results of Examples and Comparative Examples

[0052] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Calcium Nitrate, % 20 23 25 23 23 23 Polyvinyl Alcohol A A A B C D Polyvinyl Alcohol, % 2 2.5 3 2.5 2.5 2.5 Metal Salt of Stearic Acid Calcium B Calcium B Calcium B Calcium B Calcium B Calcium B Metal Salt of Stearic Acid, % 3 4 5 4 4 4 Alkyl Alcohol Ethoxylate A, % 1 1.5 2 1.5 1.5 1.5 Alkyl Alcohol Ethoxylate B, % Water Balance Balance Balance Balance Balance Balance Stickiness Level of Gloves Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion The gloves are adhered after being stored for 30 days Slight Adhesion Slight Adhesion Slight Adhesion No Adhesion No Adhesion Slight Adhesion

[0053] It can be seen from Examples 2 / 4 / 5 / 6 that the preferred degree of polymerization of polyvinyl alcohol mainly improves the adhesion during long-term storage.

[0054] Continued Table 3:

[0055] Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Calcium Nitrate, % 23 23 23 23 23 23 Polyvinyl Alcohol A A A A A A Polyvinyl Alcohol, % 2.5 2.5 2.5 2.5 2.5 2.5 Metal Salt of Stearic Acid Calcium B Calcium A Calcium E Calcium F Calcium A / Calcium C Calcium B / Calcium D Metal Salt of Stearic Acid, % 4 4 4 4 0.1 / 3.9 1 / 3 Alkyl Alcohol Ethoxylate A, % 1.5 1.5 1.5 1.5 1.5 Alkyl Alcohol Ethoxylate B, % 1.5 Water Balance Balance Balance Balance Balance Balance Stickiness Level of Gloves Moderate Adhesion Moderate Adhesion Slight Adhesion Moderate Adhesion Slight Adhesion Slight Adhesion The gloves are adhered after being stored for 30 days Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion

[0056] As can be seen from Example 2 / 7, alkyl alcohol ethoxylates with a preferred number of carbon atoms have the best glove demolding and tackiness during preparation.

[0057] As can be seen from 2 / 8 / 9 / 10 / 11, it is preferred that more than 90 wt% of the stearate has a particle size distribution between 6 - 17 microns, which is better for improving demolding properties and reducing glove tackiness.

[0058] Continued Table 3:

[0059] Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Calcium Nitrate, % 23 23 23 23 23 23 Polyvinyl Alcohol A A A A A A Polyvinyl Alcohol, % 2.5 2.5 2.5 2.5 2.5 2.5 Metal Salt of Stearic Acid Calcium B / Calcium D Calcium B / Calcium D Calcium B / Calcium D Calcium B / Calcium D / Calcium E Zinc A Zinc B Metal Salt of Stearic Acid, % 1.4 / 2.6 3.6 / 0.4 3.9 / 0.1 2 / 1 / 1 4 4 Alkyl Alcohol Ethoxylate A, % 1.5 1.5 1.5 1.5 1.5 1.5 Alkyl Alcohol Ethoxylate B, % Water Balance Balance Balance Balance Balance Balance Stickiness Level of Gloves No Adhesion No Adhesion Slight Adhesion No Adhesion Slight Adhesion Slight Adhesion The gloves are adhered after being stored for 30 days Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion Slight Adhesion

[0060] As can be seen from Examples 12 - 16, it is more preferred that the particle size distribution range of the stearate is: among the particles with a particle size between 6 - 17 microns, 35 - 90 wt% of the particles have a particle size range of 6 - 11 microns.

[0061] Continued Table 3:

[0062] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Calcium Nitrate, % 23 23 23 23 23 23 23 23 Polyvinyl Alcohol A A A A A A A Polyvinyl Alcohol, % 1 4 2.5 2.5 2.5 2.5 2.5 Metal Salt of Stearic Acid Calcium B Calcium B Calcium B Calcium B Calcium B Calcium B Calcium B Metal Salt of Stearic Acid, % 4 4 4 4 4 4 12 Alkyl Alcohol Ethoxylate A, % 1.5 1.5 1.5 0.3 3 1.5 1.5 Alkyl Alcohol Ethoxylate B, % Water Balance Balance Balance Balance Balance Balance Balance Balance Stickiness Level of Gloves Severe Adhesion Severe Adhesion Moderate Adhesion Severe Adhesion Severe Adhesion Moderate Adhesion Severe Adhesion Severe Adhesion The gloves are adhered after being stored for 30 days Severe Adhesion Severe Adhesion Moderate Adhesion Severe Adhesion Severe Adhesion Severe Adhesion Severe Adhesion Severe Adhesion

[0063] As can be seen from Comparative Examples 1 - 3, if polyvinyl alcohol is not added or the addition amount is too low, the improvement of demolding properties and adhesion during long-term storage is insufficient; but if the content is too high, it will also lead to the destruction of the coagulant composition, and instead reduce the demolding properties and adhesion during long-term storage.

[0064] As can be seen from Comparative Examples 4 - 6, if the addition amount of alkyl alcohol ethoxylate is too low, the improvement of demolding properties and adhesion during long-term storage is insufficient; but if the content is too high, it will also lead to the destruction of the coagulant composition, and instead reduce the demolding properties, especially the adhesion during long-term storage decreases significantly.

Claims

1. A coagulant for the production of nitrile gloves, characterized in that, By weight percentage, it includes the following components: Calcium nitrate 20 - 25%; Polyvinyl alcohol 2 - 3%; Metal stearate 3 - 5%; Alkyl alcohol ethoxylate 1 - 2%; Water 65 - 72%; The particle size distribution range of the metal stearate is: more than 90 wt% of the metal stearate has a particle size distribution between 6 - 17 microns; The degree of polymerization range of the polyvinyl alcohol is 23,000 - 37,000; In the alkyl alcohol ethoxylate, the alkyl alcohol chain segment contains 12 - 14 carbon atoms.

2. The coagulant for producing nitrile gloves according to claim 1, characterized in that, The degree of polymerization range of the polyvinyl alcohol is 25,000 - 35,000.

3. The coagulant for producing nitrile gloves according to claim 1, characterized in that, The particle size distribution range of the metal stearate is: among the particle sizes between 6 - 17 microns, 35 - 90 wt% of the particle size range is 6 - 11 microns.

4. The coagulant for producing nitrile gloves according to claim 1, wherein, The metal stearate is selected from at least one of calcium stearate, magnesium stearate, zinc stearate, and sodium stearate.

5. The preparation method of the coagulant for producing nitrile gloves according to any one of claims 1-4, characterized in that, It includes the following steps: Prepare a dispersion of polyvinyl alcohol, alkyl alcohol ethoxylate and water at 1500 - 1800 revolutions per minute for standby; mix and stir water and calcium nitrate to dissolve, then add the above dispersion and metal stearate and stir and mix evenly to obtain a coagulant for producing nitrile gloves.

6. A nitrile glove, characterized in that, Prepared from the coagulant according to any one of claims 1 - 4.