Yellowing-resistant carboxylic butadiene-acrylonitrile latex as well as preparation method and application thereof
By optimizing the emulsifier and initiator in the synthesis of carboxybutyron nitrile latex, using low-temperature synthesis method and complexing agent treatment, the aging and yellowing problems caused by metal ion catalysis are solved, and the preparation of high-performance yellowing resistance to carboxyron nitrile latex is achieved.
Patent Information
- Application Number
- CN202510092884.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-21
- Publication Date
- 2025-05-09
AI Technical Summary
The existing carboxyl nitrile latex needs to be added to metal ion catalysts during the synthesis process, resulting in oxidation and degradation of unsaturated bonds, causing material aging, yellowing and performance degradation.
By using emulsifiers and initiators at a temperature of 5-10°C, a free radical chain reaction is initiated, and the addition of metal ion catalysts is avoided. The low-temperature synthesis method is adopted, the addition of complexing agents is added to delay the catalytic action of metal ions, and a reducing agent is used instead of antioxidants.
The synthesis of yellow-resistant carboxylic nitrile latex under low temperature conditions is achieved, which avoids yellowing, improves product performance, reduces production costs, and expands the scope of application.
Smart Images
Figure CN119955022A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of emulsion polymerization, and in particular to a yellowing-resistant carboxyl nitrile latex and a preparation method thereof. Background Art
[0002] Carboxyl nitrile latex is a terpolymer emulsion of butadiene, acrylonitrile and a third monomer containing a carboxyl group (such as methacrylic acid, acrylonitrile, etc.). The performance of carboxyl nitrile latex is better than that of ordinary nitrile latex. It has carboxyl groups on its molecular chain and has the characteristics of self-crosslinking, so that the prepared film has excellent oil resistance, chemical resistance and wear resistance, and has good adhesion to materials such as fiber leather. The introduction of carboxyl groups also makes the latex have better mechanical properties, flow properties and high tensile strength. In addition, carboxyl nitrile latex does not contain protein and will not cause allergic reactions in the human body, so it has been widely used in the manufacture of medical examination gloves in recent years.
[0003] In the process of synthesizing carboxylated nitrile latex, the reaction temperature has a significant impact on the performance of the final product. At present, the production process of carboxylated nitrile latex usually includes two methods: medium-high temperature and medium-low temperature. The products synthesized by the medium-high temperature method for carboxylated nitrile latex often have poor performance, and the molecular structure formed by butadiene tends to be a trans structure. This structure has a high glass transition temperature (Tg), and the tensile properties and elongation are not large; while in the medium-low temperature method for synthesizing carboxylated nitrile latex, the molecular structure formed by butadiene tends to be a cis structure, and the performance of the obtained product is relatively good, but the starting temperature of the medium-low temperature method is low, and it is often necessary to add a metal ion catalyst (such as ferrous sulfate, EDTA-FeNa, etc.) for catalysis.
[0004] It is worth noting that there are a large number of carbon-carbon double bonds in the molecular chain of carboxyl nitrile latex. The presence of metal ions will cause oxidative degradation of unsaturated bonds, causing problems such as material aging, yellowing and performance degradation. This results in the need to add a large amount of antioxidants to resist oxidation during the use of nitrile latex, which not only increases production costs, but some antioxidants are also irritating to the human body, limiting their scope of application. Summary of the invention
[0005] The object of the present invention is to provide a yellowing-resistant carboxyl nitrile latex and a preparation method and application thereof, so as to solve the problems raised in the above-mentioned background technology.
[0006] To achieve the above object, the present invention provides the following technical solutions:
[0007] A method for preparing yellowing-resistant carboxylated nitrile latex, characterized in that it comprises the following steps:
[0008] S1, add deionized water, emulsifier, dispersant, acrylonitrile, unsaturated carboxylic acid, chain transfer agent, complexing agent, electrolyte and reducing agent into the reactor, then replace the air in the reactor with nitrogen, and ensure that the pressure in the reactor is -0.05 to -0.08 MPa, adjust the reaction temperature in the reactor to 5 to 50° C., add butadiene, stir evenly, and obtain a mixed solution;
[0009] S2, adding an oxidant into the reactor, confirming the start of the reaction when the temperature rises by 1-2°C, controlling the temperature in the reactor at 5-50°C during the reaction, judging the reaction to be over when the polymerization conversion rate exceeds 94%, and adding a terminator;
[0010] S3, heating the emulsion terminated in step S2, concentrating it under negative pressure, and then adding a neutralizing agent to adjust the pH to 7.5-11, thereby obtaining a yellowing-resistant carboxylated nitrile latex.
[0011] In step S2, the reaction temperature in the reactor is preferably adjusted to 5 to 50°C, less preferably 10 to 45°C, and most preferably 15 to 35°C.
[0012] Preferably, the raw materials for preparing the yellowing-resistant carboxyl nitrile latex include, by weight: 110-150 parts of deionized water, 1-5 parts of emulsifier, 0.1-3 parts of dispersant, 0.1-2 parts of chain transfer agent, 0.01-0.5 parts of complexing agent, 0.01-0.05 parts of electrolyte, 0.01-3 parts of reducing agent, 0.01-5 parts of oxidant, and 0.01-0.7 parts of terminator;
[0013] It also includes monomer raw materials: 46-94.5 parts of butadiene, 5-45 parts of acrylonitrile, and 0.5-9 parts of unsaturated carboxylic acid; the unsaturated carboxylic acid is acrylic acid or methacrylic acid, and the butadiene is butadiene after removing the polymerization inhibitor.
[0014] Among them, the deionized water is preferably 120-150 parts, and the most preferred is 120-140 parts; the emulsifier is preferably 1-4 parts, and the most preferred is 2.5-3.5 parts; the dispersant is preferably 0.5-3 parts, and the most preferred is 0.8-2.1 parts; the chain transfer agent is preferably 0.2-1.6 parts, and the most preferred is 0.5-1.2 parts; the complexing agent is preferably 0.1-0.5 parts, and the most preferred is 0.3-0.4 parts; the electrolyte is preferably 0.01-0.03 parts, and the most preferred is 0.0 1 to 0.02 parts; the reducing agent is preferably 0.05 to 2 parts, and the most preferred part is 0.08 to 1.8 parts; the oxidizing agent is preferably 0.04 to 4 parts, and the most preferred part is 0.1 to 1.2 parts; the terminator is preferably 0.05 to 0.3 parts, and the most preferred part is 0.1 to 0.2 parts; butadiene is preferably 50 to 80 parts, and the most preferred part is 55 to 75 parts; acrylonitrile is preferably 15 to 45 parts, and the most preferred part is 25 to 40 parts; the unsaturated carboxylic acid is preferably 2 to 6 parts, and the most preferred part is 3 to 6 parts.
[0015] Preferably, the emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, linear sodium dodecylbenzene sulfonate, disproportionated potassium rosin soap, alkylphenol polyoxyethylene ether (OP-10) and Tween-80; linear sodium dodecylbenzene sulfonate is most preferred, and the emulsion system using linear sodium dodecylbenzene sulfonate as the emulsifier is relatively more stable.
[0016] Preferably, the dispersant is one or more of benzylnaphthalenesulfonic acid formaldehyde condensate, 2-naphthalenesulfonic acid formaldehyde polymer sodium salt (dispersant NNO) and sodium polynaphthalene formaldehyde sulfonate.
[0017] Preferably, the chain transfer agent is one or both of n-dodecyl mercaptan and tert-dodecyl mercaptan.
[0018] Preferably, the complexing agent is one or more of sodium tripolyphosphate, triethanolamine, ethylenediaminetetraacetate (EDTA-2Na or EDTA-4Na) and diethylenetriaminepentacarboxylate.
[0019] Preferably, the reducing agent and the oxidizing agent constitute an initiator, the reducing agent is one or more of bleaching powder, sodium bisulfite, thiourea dioxide and sodium pyrosulfite, and the oxidizing agent is one or two of p-menthane hydroperoxide and di(2-ethylhexyl) peroxydicarbonate; p-menthane hydroperoxide and di(2-ethylhexyl) peroxydicarbonate are selected as the oxidizing agent, and a free radical chain reaction can be initiated at 5-10°C through a low-temperature oxidation-reduction initiation system without the participation of a catalyst.
[0020] Preferably, the electrolyte is one or a combination of potassium chloride and sodium chloride.
[0021] Preferably, the neutralizing agent is one or more of aqueous ammonia, sodium hydroxide solution and potassium hydroxide solution.
[0022] Preferably, the terminator is one or more of sodium thiram, sodium polysulfide and sodium nitrite.
[0023] Another aspect of the present invention discloses yellowing-resistant carboxylated nitrile latex prepared by the method for preparing yellowing-resistant carboxylated nitrile latex described in any one of the above technical solutions.
[0024] The invention also discloses application of the yellowing-resistant carboxyl nitrile latex in medical gloves.
[0025] The beneficial effects of the above technical solution of the present invention are as follows:
[0026] 1. The present invention can initiate a free radical chain reaction at a temperature of 5-10°C by optimizing the emulsifier and the initiator. During the reaction, no metal ion catalyst such as Fe and Cu needs to be added. The reaction starting temperature is low and the reaction rate is moderate. The generation of more gel in the emulsion can be avoided, and the yellowing phenomenon of the product in the application can be avoided. The performance of the product synthesized at low temperature is also more superior.
[0027] 2. The present invention can adapt to a wider reaction temperature range (5-50° C.). When the synthesized carboxyl nitrile latex is used in the preparation of medical gloves, not only is the whiteness significantly better than that of conventional latex, but the indicators such as elongation at break and tensile strength are also further improved.
[0028] 3. The present invention adds a complexing agent to the reaction system in the early stage of the reaction, which delays the catalytic effect of the residual metal ions in the raw materials in the carboxyl nitrile latex. The addition of a reducing agent replaces the effect of the antioxidant, avoiding the use of a large amount of antioxidants or even no antioxidants in the later stage, making the carboxyl nitrile latex products more resistant to oxidation, aging and yellowing than conventional products. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:
[0030] Figure 1 It is a schematic diagram of the main process of the present invention. DETAILED DESCRIPTION
[0031] In order to make the present application easier to understand, the present application will be further described in detail below in conjunction with the examples, which are merely illustrative and are not intended to limit the scope of application of the present application. The raw materials or components used in the present application can be obtained through commercial routes or conventional methods unless otherwise specified.
[0032] The terms "comprises", "comprising", "having" and their derivatives as used herein are not intended to exclude the presence of any additional components, steps or processes, whether or not specifically disclosed. In order to avoid any doubt, all compositions claimed through the use of the term "comprising" may include any additional additives, adjuvants or compounds, whether polymeric or otherwise, unless otherwise indicated.
[0033] A yellowing-resistant carboxyl nitrile latex and a preparation method thereof, such as Figure 1 As shown, the specific steps include:
[0034] (1) Preparation:
[0035] The emulsifier and dispersant are mixed and dissolved with water to form an emulsion, the amount of the emulsifier is 1 to 5 parts, preferably 1 to 4 parts, and most preferably 2.5 to 3.5 parts; the amount of the dispersant is 0.1 to 3 parts, preferably 0.5 to 3 parts, and most preferably 0.8 to 2.1 parts, and the concentration of the emulsifier after dissolution is 1-5%
[0036] The emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, linear sodium dodecylbenzene sulfonate, potassium disproportionate rosin soap, OP-10 and Tween-80; the dispersant is one or more of benzylnaphthalenesulfonic acid formaldehyde condensate, 2-naphthalenesulfonic acid formaldehyde polymer sodium salt (dispersant NNO) and sodium polynaphthalene formaldehyde sulfonate; linear sodium dodecylbenzene sulfonate is most preferred, and the emulsion system using linear sodium dodecylbenzene sulfonate as the emulsifier is relatively more stable.
[0037] The chain transfer agent is dissolved or dispersed in water, the amount of the chain transfer agent is 0.1 to 2 parts, the second preferred amount is 0.2 to 1.6 parts, and the most preferred amount is 0.5 to 1.2 parts. The concentration of the dissolved chain transfer agent solution is 0.1 to 10%. The chain transfer agent is one or a combination of n-dodecyl mercaptan and tert-dodecyl mercaptan.
[0038] The complexing agent is dissolved in water, the amount of the complexing agent is 0.01-0.5 parts, the second preferred amount is 0.1-0.5 parts, and the most preferred amount is 0.3-0.4 parts. The concentration of the complexing agent solution after dissolution is 0.01-10%; the complexing agent is one or more of sodium tripolyphosphate, triethanolamine, ethylenediaminetetraacetate and diethylenetriaminepentacarboxylate.
[0039] The electrolyte is dissolved in water, the amount of the electrolyte is 0.01-0.05 parts, the second preferred amount is 0.01-0.03 parts, and the most preferred amount is 0.01-0.02 parts. The concentration of the dissolved electrolyte solution is 0.01%-10%. The electrolyte is one or a combination of potassium chloride and sodium chloride.
[0040] The reducing agent in the initiator is dissolved in water, the amount of the reducing agent is 0.01 to 3 parts, the second preferred amount is 0.05 to 2 parts, and the most preferred amount is 0.08 to 1.8 parts. The concentration of the reducing agent after dissolution is 0.01 to 10%. The reducing agent is one or more of bleaching powder, sodium bisulfite, thiourea dioxide and sodium pyrosulfite.
[0041] (2) Mixing
[0042] Deionized water is poured into the reaction kettle, the amount of deionized water is 110-150 parts, the second preferred amount is 120-150 parts, and the most preferred amount is 120-140 parts; then the mixed emulsion of the emulsifier and dispersant in the above steps is poured into the reaction kettle and stirred evenly.
[0043] Add acrylonitrile and unsaturated carboxylic acid into a reaction kettle and mix them, wherein the amount of acrylonitrile is 5 to 45 parts, the second preferred amount is 15 to 45 parts, and the most preferred amount is 25 to 40 parts, and the amount of unsaturated carboxylic acid is 0.5 to 9 parts, the second preferred amount is 2 to 6 parts, and the most preferred amount is 3 to 6 parts;
[0044] The chain transfer agent solution, complexing agent solution, electrolyte solution and reducing agent solution prepared in step (1) are respectively pumped into the reaction kettle for mixing.
[0045] The reactor is evacuated with a vacuum pump and nitrogen is passed through, and this is repeated three times to completely replace the air, and finally the pressure in the reactor is maintained at -0.05 to -0.08 MPa, and then butadiene is added to the reactor and mixed evenly. The amount of butadiene is 46 to 94.5 parts, the second preferred amount is 50 to 80 parts, and the most preferred amount is 55 to 75 parts. After the butadiene is added, there is a certain pressure in the reactor; during this period, the temperature in the reactor is adjusted to 5 to 50°C, the second preferred amount is 10 to 45°C, and the most preferred amount is 15 to 35°C.
[0046] (3) Synthesis
[0047] The oxidant in the initiator is dissolved and injected into the reaction kettle, and the temperature is 5-39° C. The amount of the oxidant is 0.01-5 parts, the second preferred amount is 0.04-4 parts, and the most preferred amount is 0.1-1.2 parts. The concentration of the dissolved oxidant solution is 0.01-10%; the oxidant is one or two of p-menthane hydroperoxide and di(2-ethylhexyl) peroxydicarbonate; p-menthane hydroperoxide and di(2-ethylhexyl) peroxydicarbonate are selected as the oxidant, and a free radical chain reaction can be initiated at 5-10° C. through a low-temperature oxidation-reduction initiation system without the participation of a catalyst.
[0048] After the temperature in the reactor starts to rise by 1-2°C, the reaction is confirmed to have started, and the temperature in the reactor is controlled to be 5-50°C to prevent the reaction speed from accelerating. During the heating process, circulating water is used to cool down the temperature appropriately. When the polymerization conversion rate exceeds 94%, the reaction is completed, and the emulsion is introduced into the concentration kettle, and a terminator is added. The amount of the terminator is 0.01-0.7 parts, the second preferred amount is 0.05-0.3 parts, and the most preferred amount is 0.1-0.2 parts; the terminator is one or more of sodium thiamethoxam, sodium polysulfide, and sodium nitrite.
[0049] (4) Products
[0050] The emulsion terminated in step (4) is heated, concentrated under negative pressure, and then a neutralizing agent is added to adjust the pH to 7.5-11 to obtain a yellowing-resistant carboxylated nitrile latex. The neutralizing agent is one or more of ammonia water, sodium hydroxide solution and potassium hydroxide solution.
[0051] Example 1
[0052] 140 parts of deionized water were pumped into the reactor as bottom water, and then a mixed emulsion of linear sodium dodecylbenzene sulfonate and dispersant NNO was pumped into the reactor and stirred evenly, wherein the amount of linear sodium dodecylbenzene sulfonate was 2 parts, the concentration of the linear sodium dodecylbenzene sulfonate emulsion was 3%, and the amount of dispersant NNO was 2 parts.
[0053] 28 parts of acrylonitrile and 4 parts of methacrylic acid are added into a reaction kettle and mixed, and then 5% concentration of n-dodecyl mercaptan solution (the amount of n-dodecyl mercaptan is 0.3 parts), 5% concentration of EDTA-2Na solution (the amount of EDTA-2Na is 0.2 parts), 0.5% concentration of potassium chloride solution (the amount of potassium chloride is 0.01 parts) and 2% concentration of sodium bisulfite solution (the amount of sodium bisulfite is 1 part) are added.
[0054] The air in the reactor was replaced with nitrogen three times, and the pressure in the reactor was finally maintained at -0.05 to -0.08 MPa. Then 68 parts of butadiene were added into the reactor and mixed evenly. During this period, the temperature in the reactor was adjusted to 5°C.
[0055] Dissolve 1 part of p-menthane hydroperoxide and 2 parts of di(2-ethylhexyl) peroxydicarbonate into a 5% solution, and then add it into a reactor. After the reaction starts, control the reaction temperature at 5-15°C, and measure the dry matter every hour. When the polymerization conversion rate exceeds 94%, the reaction is completed, and then the emulsion is introduced into a concentration reactor, and 0.1 parts of sodium polysulfide are added.
[0056] The terminated emulsion is heated, concentrated under negative pressure, and then ammonia water is added to adjust the pH to 8 to obtain yellowing-resistant carboxylated nitrile latex.
[0057] Example 2
[0058] 110 parts of deionized water were pumped into the reactor as bottom water, and then the mixed emulsion of disproportionate potassium rosin soap and sodium polynaphthaldehyde sulfonate was pumped into the reactor and stirred evenly, wherein the amount of disproportionate potassium rosin soap was 1 part, the concentration of the disproportionate potassium rosin soap emulsion was 2%, and the amount of sodium polynaphthaldehyde sulfonate was 0.2 part.
[0059] 15 parts of acrylonitrile and 6 parts of methacrylic acid are all added into a reaction kettle and mixed, and then 5% concentration of tert-dodecyl mercaptan solution (tert-dodecyl mercaptan is used in an amount of 1 part), 8% concentration of sodium tripolyphosphate solution (sodium tripolyphosphate is used in an amount of 0.4 part), 2% concentration of sodium chloride solution (sodium chloride is used in an amount of 0.03 part) and 2% concentration of thiourea dioxide solution (thiourea dioxide is used in an amount of 0.08 part) are added.
[0060] The air in the reactor was replaced with nitrogen three times, and the pressure in the reactor was finally maintained at -0.05 to -0.08 MPa. Then 79 parts of butadiene were added into the reactor and mixed evenly. During this period, the temperature in the reactor was adjusted to 35°C.
[0061] Dissolve 0.2 parts of hydrogen peroxide in para-menthane into a 2% solution, and then add it to the reactor. After the reaction starts, control the reaction temperature at 25-40°C, and measure the dry matter every hour. When the polymerization conversion rate exceeds 94%, the reaction is completed, and then the emulsion is introduced into a concentration kettle, and 0.3 parts of sodium thiamethoxam is added.
[0062] The terminated emulsion is heated, concentrated under negative pressure, and then ammonia water is added to adjust the pH to 10 to obtain yellowing-resistant carboxylated nitrile latex.
[0063] Example 3
[0064] 150 parts of deionized water were pumped into the reactor as bottom water, and then a mixed emulsion of linear sodium dodecylbenzene sulfonate and dispersant NNO was pumped into the reactor and stirred evenly, wherein the amount of linear sodium dodecylbenzene sulfonate was 5 parts, the concentration of the linear sodium dodecylbenzene sulfonate emulsion was 3%, and the amount of dispersant NNO was 2.5 parts.
[0065] 40 parts of acrylonitrile and 9 parts of methacrylic acid are all put into a reaction kettle and mixed, and then 3% concentration of n-dodecyl mercaptan solution (the amount of n-dodecyl mercaptan is 1.5 parts), 2% concentration of triethanolamine solution (the amount of triethanolamine is 0.1 parts), 5% concentration of potassium chloride solution (the amount of potassium chloride is 0.05 parts) and 10% concentration of sodium bisulfite solution (the amount of sodium bisulfite is 2 parts) are added.
[0066] The air in the reactor was replaced with nitrogen three times, and the pressure in the reactor was finally maintained at -0.05 to -0.08 MPa. Then 51 parts of butadiene were added to the reactor and mixed evenly. During this period, the temperature in the reactor was adjusted to 10°C.
[0067] Dissolve 5 parts of di(2-ethylhexyl) peroxydicarbonate into a 10% solution and then add it to the reactor. After the reaction starts, control the reaction temperature at 5-25°C and measure the dry matter every hour. When the polymerization conversion rate exceeds 94%, the reaction is completed. Then, the emulsion is introduced into a concentration reactor and 0.7 parts of sodium polysulfide is added.
[0068] The terminated emulsion is heated, concentrated under negative pressure, and then ammonia water is added to adjust the pH to 7.5 to obtain yellowing-resistant carboxylated nitrile latex.
[0069] Example 4
[0070] 130 parts of deionized water were pumped into the reactor as bottom water, and then a mixed emulsion of OP-10 and benzylnaphthalenesulfonic acid formaldehyde condensate was pumped into the reactor and stirred evenly, wherein the amount of OP-10 was 4 parts, the concentration of OP-10 emulsion was 5%, and the amount of benzylnaphthalenesulfonic acid formaldehyde condensate was 1 part.
[0071] 28 parts of acrylonitrile and 2 parts of methacrylic acid are all put into a reaction kettle and mixed, and then 5% concentration of tert-dodecyl mercaptan solution (tert-dodecyl mercaptan is used in an amount of 2 parts), 5% concentration of EDTA-2Na solution (EDTA-2Na is used in an amount of 0.4 parts), 5% concentration of potassium chloride solution (potassium chloride is used in an amount of 0.04 parts) and 5% concentration of sodium bisulfite solution (sodium bisulfite is used in an amount of 0.5 parts) are added.
[0072] The air in the reactor was replaced with nitrogen three times, and the pressure in the reactor was finally maintained at -0.05 to -0.08 MPa. Then 70 parts of butadiene were added into the reactor and mixed evenly. During this period, the temperature in the reactor was adjusted to 20°C.
[0073] Dissolve 1 part of di(2-ethylhexyl) peroxydicarbonate into a solution with a concentration of 8%, and then add it to the reactor. After the reaction starts, control the reaction temperature at 15-40°C and measure the dry matter every hour. When the polymerization conversion rate exceeds 94%, the reaction is completed. Then, the emulsion is introduced into a concentration kettle and 0.5 parts of sodium thiamethoxam are added.
[0074] The terminated emulsion is heated, concentrated under negative pressure, and then ammonia water is added to adjust the pH to 8 to obtain yellowing-resistant carboxylated nitrile latex.
[0075] Example 5
[0076] 120 parts of deionized water were pumped into the reactor as bottom water, and then a mixed emulsion of sodium dodecyl sulfate and dispersant NNO was pumped into the reactor and stirred evenly, wherein the amount of sodium dodecyl sulfate was 2 parts, the concentration of the sodium dodecyl sulfate emulsion was 2%, and the amount of dispersant NNO was 0.8 parts.
[0077] 28 parts of acrylonitrile and 4 parts of methacrylic acid are all added into a reaction kettle and mixed, and then 10% concentration of n-dodecyl mercaptan solution (1 part of n-dodecyl mercaptan), 5% concentration of diethylenetriamine pentacarboxylate solution (0.4 part of diethylenetriamine pentacarboxylate), 7% concentration of sodium chloride solution (0.01 part of potassium chloride) and 7% concentration of sodium pyrosulfite solution (0.08 part of sodium pyrosulfite) are added.
[0078] The air in the reactor was replaced with nitrogen three times, and the pressure in the reactor was finally maintained at -0.05 to -0.08 MPa. Then 68 parts of butadiene were added into the reactor and mixed evenly. During this period, the temperature in the reactor was adjusted to 45°C.
[0079] Dissolve 0.2 parts of hydrogen peroxide in para-menthane into a 2% solution, and then add it to the reactor. After the reaction starts, control the reaction temperature at 35-50°C and measure the dry matter every hour. When the polymerization conversion rate exceeds 94%, the reaction is completed. Then, the emulsion is introduced into a concentration reactor and 0.1 parts of sodium nitrite is added.
[0080] The terminated emulsion is heated, concentrated under negative pressure, and then ammonia water is added to adjust the pH to 9 to obtain yellowing-resistant carboxylated nitrile latex.
[0081] Comparative Example
[0082] The yellowing-resistant carboxyl nitrile latex prepared in Examples 1-5 and market products 1-4 were respectively produced into medical rubber gloves, and their tensile strength, elongation at break and aging yellowing time were tested. The test method adopted GB 10213-2006 standard, and the test results are shown in the following table:
[0083]
[0084] It can be seen from the test results that the medical gloves prepared in Examples 1-5 of the present invention show significant advantages in tensile strength, elongation at break and aging yellowing time at 120° C., and are specifically superior to market products 1-4 in terms of:
[0085] In terms of tensile strength, Examples 1-5 are generally higher than market products, wherein the tensile strength of Example 5 is close to that of Market Products 1 and 3, but compared thereto, Example 5 has a higher elongation at break and a longer aging yellowing time at 120°C, which indicates that the latex of the present invention has stronger comprehensive performance. Among them, the tensile strengths of Examples 3 and 4 reached 38.5 and 38.2 MPa, respectively, the elongation at break of Examples 2 and 4 reached 802% and 811%, respectively, and the yellowing aging time of Examples 1-5 was greater than that of market products. This means that the latex prepared by the present invention has higher mechanical strength, greater elastic deformation capacity, and longer resistance to aging and yellowing.
[0086] In summary, the latex synthesized at low temperature without adding metal ions not only improves the basic mechanical properties of the material, but also enhances its heat stability and anti-aging properties. This improvement is of great significance for improving product quality, expanding the scope of application, and meeting higher standards of industrial needs.
[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.
Claims
1. A method for preparing a yellowing-resistant carboxylated nitrile latex, characterized in that: The following steps are involved: S1, add deionized water, emulsifier, dispersant, acrylonitrile, unsaturated carboxylic acid, chain transfer agent, complexing agent, electrolyte and reducing agent into the reactor, then replace the air in the reactor with nitrogen, and ensure that the pressure in the reactor is -0.05 to -0.08 MPa, adjust the reaction temperature in the reactor to 5 to 50° C., add butadiene, stir evenly, and obtain a mixed solution; S2, adding an oxidant into the reactor, confirming the start of the reaction when the temperature rises by 1-2°C, controlling the temperature in the reactor at 5-50°C during the reaction, judging the reaction to be over when the polymerization conversion rate exceeds 94%, and adding a terminator; S3, heating the emulsion terminated in step S2, concentrating it under negative pressure, and then adding a neutralizing agent to adjust the pH to 7.5-11, thereby obtaining a yellowing-resistant carboxylated nitrile latex; Wherein, the emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, linear sodium dodecylbenzene sulfonate, disproportionated potassium rosin soap, OP-10 and Tween-80; The reducing agent and the oxidizing agent together constitute the initiator, the reducing agent is one or more of bleaching powder, sodium bisulfite, thiourea dioxide and sodium pyrosulfite; the oxidizing agent is one or two of p-menthane hydroperoxide and di(2-ethylhexyl) peroxydicarbonate.
2. The method for preparing the yellowing-resistant carboxyl nitrile latex according to claim 1, wherein: The raw materials for preparing the yellowing-resistant carboxyl nitrile latex include, by mass fraction, 110-150 parts of deionized water, 1-5 parts of emulsifier, 0.1-3 parts of dispersant, 0.1-2 parts of chain transfer agent, 0.01-0.5 parts of complexing agent, 0.01-0.05 parts of electrolyte, 0.01-3 parts of reducing agent, 0.01-5 parts of oxidant and 0.01-0.7 parts of terminator; The invention also comprises monomer raw materials: 46-94.5 parts of butadiene, 5-45 parts of acrylonitrile and 0.5-9 parts of unsaturated carboxylic acid, wherein the unsaturated carboxylic acid is acrylic acid or methacrylic acid.
3. The method for preparing the yellowing-resistant carboxyl nitrile latex according to claim 1, wherein: The dispersant is one or more of benzylnaphthalenesulfonic acid formaldehyde condensate, 2-naphthalenesulfonic acid formaldehyde polymer sodium salt (dispersant NNO) and sodium polynaphthalene formaldehyde sulfonate.
4. The method for preparing the yellowing-resistant carboxyl nitrile latex according to claim 1, wherein: The chain transfer agent is one or both of n-dodecyl mercaptan and tert-dodecyl mercaptan.
5. The method for preparing the yellowing-resistant carboxyl nitrile latex according to claim 1, wherein: The complexing agent is one or more of sodium tripolyphosphate, triethanolamine, ethylenediaminetetraacetate and diethylenetriaminepentacarboxylate.
6. The method for preparing the yellowing-resistant carboxyl nitrile latex according to claim 1, wherein: The electrolyte is one or a combination of potassium chloride and sodium chloride.
7. The method for preparing the yellowing-resistant carboxyl nitrile latex according to claim 1, characterized in that: The terminator is one or more of sodium thiram, sodium polysulfide and sodium nitrite.
8. The method for preparing the yellowing-resistant carboxyl nitrile latex according to claim 1, characterized in that: The neutralizing agent is one or more of ammonia water, sodium hydroxide solution and potassium hydroxide solution.
9. The yellowing-resistant carboxyl nitrile latex prepared by the preparation method of the yellowing-resistant carboxyl nitrile latex according to any one of claims 1 to 8.
10. Use of the yellowing-resistant carboxyl nitrile latex according to claim 9 in medical gloves.