CN116003704A - Nitrile latex, preparation method thereof, hydrogenated nitrile rubber latex, nitrile latex composition and nitrile latex vulcanized rubber - Google Patents
Nitrile latex, preparation method thereof, hydrogenated nitrile rubber latex, nitrile latex composition and nitrile latex vulcanized rubber Download PDFInfo
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Abstract
The invention relates to the field of synthetic rubber, and discloses nitrile rubber latex, a preparation method thereof, hydrogenated nitrile rubber latex, a nitrile rubber latex composition and nitrile rubber latex vulcanized rubber. The method at least sequentially comprises a layer A, a layer B and a layer C along the direction from the center of nitrile rubber particles in the nitrile rubber latex to the outer surface; layer A is provided by copolymer A, the bound acrylonitrile content of copolymer A is greater than or equal to 40wt%; layer B is provided by copolymer B having a bound acrylonitrile content of 30 to 35 wt.%; layer C is provided by copolymer C having a bound acrylonitrile content of 20 to 25 wt.%. The nitrile latex with the specific structure can have excellent oil resistance and mechanical property.
Description
Technical Field
The invention relates to the field of synthetic rubber, in particular to a nitrile latex and a preparation method thereof, hydrogenated nitrile rubber latex, a nitrile latex composition and nitrile latex vulcanized rubber.
Background
Butadiene-acrylonitrile copolymer rubber, namely nitrile rubber for short, is a random copolymer of butadiene and acrylonitrile formed by emulsion polymerization, and has excellent oil resistance, excellent wear resistance, excellent solvent resistance and excellent heat resistance in a wider temperature range because the molecular structure of the polymer contains polar groups of nitrile groups and unsaturated double bonds. Nitrile rubber has two application forms, one is emulsion polymerization to obtain emulsion, and is called nitrile latex for short, and is often used for producing gloves, latex products, adhesives and the like. The other is emulsion polymerization, which is demulsified and dried to give a solid form, commonly known as nitrile rubber. Rubber rings, rubber mats, rubber tubes, rubber belts, foamed products and the like are produced after mixing with carbon black and the like and vulcanization.
The sudden onset of public health events has led to a tremendous increase in the demand for protective gloves, resulting in a shortage of nitrile latex. Protective gloves require that the nitrile latex provide excellent barrier properties against the ingress of oily molecules in the case of thinner materials (ensuring wearing comfort and handling flexibility), i.e., that the nitrile latex possess excellent oil resistance. On the other hand, the protective glove also requires that the nitrile latex has better elasticity, and is not easy to be damaged due to stretching deformation during wearing and use, namely, the nitrile latex is required to have higher elongation at break and stretching stress.
At present, relatively few studies are conducted in this respect, and how to improve the oil resistance, elongation at break and tensile stress of the nitrile latex is rarely reported in the prior art.
Disclosure of Invention
The invention aims to solve the problems of poor oil resistance, poor elongation at break and poor stretching stress of the prior art of nitrile latex, and provides a nitrile latex, a preparation method thereof, hydrogenated nitrile rubber latex, a nitrile latex composition and nitrile latex vulcanized rubber. The nitrile latex with the specific structure can have excellent oil resistance and provide good elongation at break and stress at definite elongation.
In order to achieve the above object, a first aspect of the present invention provides a nitrile latex characterized by comprising at least a three-layer structure of layer a, layer B and layer C in this order in a direction from the center to the outer surface of rubber particles in the nitrile latex;
wherein the layer a is provided by a copolymer a having a bound acrylonitrile content of 40wt% or more based on the total weight of the copolymer a;
the layer B is provided by a copolymer B, and the content of bound acrylonitrile is 30-35wt% based on the total weight of the copolymer B;
the layer C is provided by a copolymer C having a bound acrylonitrile content of 20 to 25 wt.%, based on the total weight of the copolymer C.
The second aspect of the invention provides a method for preparing a nitrile latex, which is characterized by comprising the following steps:
s1, carrying out a first reaction of acrylonitrile A, butadiene A and an emulsifier in water in the presence of an initiator to obtain a latex A comprising nitrile rubber particles A containing a layer A provided by a copolymer A;
s2, adding acrylonitrile B, butadiene B and a first molecular weight regulator into the latex A for a second reaction to obtain latex B containing nitrile rubber particles B, wherein the latex B sequentially comprises a layer A provided by a copolymer A and a layer B provided by the copolymer B along the direction from the center of the nitrile rubber particles B to the outer surface;
S3, adding acrylonitrile C, butadiene C and a second molecular weight regulator into the latex B for a third reaction to obtain a nitrile latex containing nitrile rubber particles C, wherein the nitrile latex sequentially comprises a layer A provided by a copolymer A, a layer B provided by a copolymer B and a layer C provided by the copolymer C along the direction from the center of the nitrile rubber particles C to the outer surface;
wherein the conditions of the first reaction are such that the copolymer A obtained in the first reaction has a bound acrylonitrile content of 40wt% or more based on the total weight of the copolymer A, and the diameter of the nitrile rubber particles A in the latex A is 50 to 90nm;
the conditions of the second reaction are such that, in the second reaction, a copolymer B is obtained, the bound acrylonitrile content being from 30 to 35% by weight, based on the total weight of the copolymer B, the diameter of the nitrile rubber particles B in the latex B being from 100 to 140nm;
the conditions of the third reaction are such that, in the third reaction, a copolymer C is obtained, the bound acrylonitrile content being 20 to 25% by weight, based on the total weight of the copolymer C, and the diameter of the nitrile rubber particles C in the latex C being 150 to 200nm.
In a third aspect, the present invention provides a nitrile latex prepared by the above-described preparation method.
In a fourth aspect, the present invention provides a hydrogenated nitrile rubber latex, characterized in that it is obtained by hydrogenation of the above nitrile rubber latex.
In a fifth aspect, the present invention provides a nitrile latex composition, characterized in that the nitrile latex composition comprises the nitrile latex described above.
The sixth aspect of the invention provides a nitrile latex vulcanized rubber, which is characterized by being prepared by mixing and vulcanizing the nitrile latex composition.
Through the technical scheme, the nitrile latex and the preparation method thereof, the hydrogenated nitrile rubber latex, the nitrile latex composition and the nitrile latex vulcanized rubber have the following beneficial effects:
the nitrile latex provided by the invention has a multi-layer structure, and each layer structure of the nitrile latex respectively comprises the copolymer A, the copolymer B and the copolymer C with specific combined acrylonitrile content, so that the nitrile latex vulcanized rubber has excellent oil resistance, and the breaking elongation and the stretching stress of the nitrile latex vulcanized rubber are obviously improved, and the nitrile latex vulcanized rubber is particularly suitable for producing thin gloves.
According to the preparation method of the nitrile latex, provided by the invention, the polymerization monomers are fed step by step and polymerized step by step, and the specific particle diameter and the specific acrylonitrile combination amount are obtained in each stage by controlling the reaction conditions of each stage, so that the nitrile latex vulcanized rubber has excellent oil resistance, elongation at break and stretching stress, and the composition and structure of the polymer can be controlled by the method, thereby being beneficial to large-scale industrial stable production.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The first aspect of the invention provides a nitrile latex, which is characterized by comprising at least a three-layer structure of a layer A, a layer B and a layer C in sequence along the direction from the center to the outer surface of rubber particles in the nitrile latex;
wherein the layer a is provided by a copolymer a having a bound acrylonitrile content of 40wt% or more based on the total weight of the copolymer a;
the layer B is provided by a copolymer B, and the content of bound acrylonitrile is 30-35wt% based on the total weight of the copolymer B;
the layer C is provided by a copolymer C having a bound acrylonitrile content of 20 to 25 wt.%, based on the total weight of the copolymer C.
The nitrile rubber particles in the nitrile latex provided by the invention have a multilayer structure and comprise the copolymer A, the copolymer B and the copolymer C with the combined acrylonitrile content, so that the nitrile latex has excellent oil resistance, elongation at break and stretching stress after vulcanization, and has excellent application performance.
Further, when the acrylonitrile content is more than 45wt%, preferably more than 50wt%, based on the total weight of the copolymer A, the swelling degree of the nitrile latex vulcanized rubber is further reduced and the oil resistance is further improved.
Further, the diameter of the layer A is 50-90nm, the sum of the diameters of the layer A and the layer B is 100-140nm, and the sum of the diameters of the layer A, the layer B and the layer C is 150-200nm.
According to the invention, the insolubles in chlorobenzene are less than 1% by weight, preferably less than 0.5% by weight, based on the total weight of the rubber particles in the nitrile latex.
According to the present invention, further comprising adding a vinyl unsaturated carboxylic acid in step S3;
further, the content of the structural unit provided by the ethylenically unsaturated carboxylic acid is 1 to 5% by weight based on the total weight of the rubber particles in the nitrile latex.
In the present invention, when the nitrile latex has an insoluble content of less than 1wt% in chlorobenzene and the content of the structural unit provided by the ethylenically unsaturated carboxylic acid satisfies the above range, the best oil resistance, elongation at break and elongation stress can be obtained.
In the present invention, the number average molecular weight of the nitrile latex is 4X 10 4 -10×10 4 。
The second aspect of the invention provides a method for preparing a nitrile latex, which is characterized by comprising the following steps:
S1, carrying out a first reaction of acrylonitrile A, butadiene A and an emulsifier in water in the presence of an initiator to obtain a latex A comprising nitrile rubber particles A containing a layer A provided by a copolymer A;
s2, adding acrylonitrile B, butadiene B and a first molecular weight regulator into the latex A for a second reaction to obtain latex B containing nitrile rubber particles B, wherein the latex B sequentially comprises a layer A provided by a copolymer A and a layer B provided by the copolymer B along the direction from the center of the nitrile rubber particles B to the outer surface;
s3, adding acrylonitrile C, butadiene C and a second molecular weight regulator into the latex B for a third reaction to obtain a nitrile latex containing nitrile rubber particles C, wherein the nitrile latex sequentially comprises a layer A provided by a copolymer A, a layer B provided by a copolymer B and a layer C provided by the copolymer C along the direction from the center of the nitrile rubber particles C to the outer surface;
wherein the conditions of the first reaction are such that the copolymer A obtained in the first reaction has a bound acrylonitrile content of 40wt% or more based on the total weight of the copolymer A, and the diameter of the nitrile rubber particles A in the latex A is 50 to 90nm;
the conditions of the second reaction are such that, in the second reaction, a copolymer B is obtained, the bound acrylonitrile content being from 30 to 35% by weight, based on the total weight of the copolymer B, the diameter of the nitrile rubber particles B in the latex B being from 100 to 140nm;
The conditions of the third reaction are such that, in the third reaction, a copolymer C is obtained, the bound acrylonitrile content being 20 to 25% by weight, based on the total weight of the copolymer C, and the diameter of the nitrile rubber particles C in the latex C being 150 to 200nm.
According to the invention, the butadiene and the acrylonitrile are fed step by step and polymerized in stages, and the latex particles with specific particle diameters are obtained by controlling the first reaction condition, the second reaction condition and the third reaction condition, and the copolymer obtained in each stage has specific acrylonitrile combination amount, so that the obtained nitrile latex vulcanized rubber has excellent oil resistance, elongation at break and stretching stress.
Furthermore, in the invention, water is used as a solvent, so that a polymerization system containing an initiator, a molecular weight regulator, acrylonitrile and butadiene is heterogeneous, the probability of forming branched and netlike macromolecules by collision of free radicals in the system is greatly reduced, and meanwhile, more importantly, a proper amount of the molecular weight regulator is introduced in the second reaction stage and the third reaction stage, the reaction temperature is strictly controlled, and the generation of branched and netlike macromolecules is remarkably inhibited. Thereby remarkably reducing the content of insoluble substances in chlorobenzene in the prepared nitrile latex and further improving the elongation at break and the stretching stress of the nitrile latex vulcanized rubber.
In the present invention, the content of insoluble matter in chlorobenzene is less than 1% by weight, preferably less than 0.5% by weight, based on the total weight of rubber particles in the nitrile latex.
Further, in the first reaction, the acrylonitrile is used in an amount of 41wt% or more, preferably 41 to 55wt% based on the total weight of acrylonitrile A and butadiene A.
Further, in the second reaction, the acrylonitrile is used in an amount of 28 to 32wt% based on the total weight of acrylonitrile B and butadiene B.
Further, in the third reaction, the acrylonitrile is used in an amount of 17 to 24wt% based on the total weight of acrylonitrile C and butadiene C.
According to the present invention, further comprising adding a vinyl unsaturated carboxylic acid in step S3;
further, in the third reaction, the ethylenically unsaturated carboxylic acid is used in an amount of 1 to 5% by weight based on the total weight of all acrylonitrile and butadiene.
In the invention, the method further comprises the following steps: after the first reaction, a small amount of latex a containing the copolymer was taken and the diameter of layer a, the bound acrylonitrile content (A1) and the conversion (C1) in latex a were tested;
after the second reaction, a small amount of latex B was taken and the sum of the diameters of layer a and layer B in latex B was tested, combined with acrylonitrile content (A2) and conversion (C2);
After the third reaction, a small amount of latex C was taken and the sum of the diameters of layer A, layer B and layer C in latex C was tested, in combination with the acrylonitrile content (A3) and the conversion (C3).
Wherein, according to the reaction process, after the second reaction, the bound acrylonitrile content (A2) of the sample test is the bound acrylonitrile content of the copolymer mixture obtained by the first reaction and the second reaction; after the third reaction, the bound acrylonitrile content (A3) of the sample test was the bound acrylonitrile content of the copolymer mixture obtained by the first reaction, the second reaction and the third reaction. Accordingly, the bound acrylonitrile content (A20) in the copolymer (copolymer B) obtained in the second reaction can be calculated according to the formula (1), and the bound acrylonitrile content (A30) in the copolymer (copolymer C) obtained in the third reaction can be calculated according to the formula (2).
A20 = ((m1×c1+ (m2+m1× (1-C1)) ×c2) ×a2—m1×c1×a1)/((m2+m1× (1-C1)) ×c2) formula (1)
A30 = (m1×c1+ (m2+m1× (1-C1)) ×c2+ (m3+m2× (1-C2)) ×c3) ×a3- (m1×c1+ (m2+m1× (1-C1)) ×c2)/(m3+m2× (1-C2)) ×c3) formula (2)
Wherein m1, m2, m3 are the total amount of acrylonitrile and butadiene added respectively for the first reaction, the second reaction and the third reaction, respectively.
In the present invention, the initiator is a redox initiator, wherein the oxidizing agent is selected from oxidizing agents conventional in the art, for example, the oxidizing agent is selected from at least one of dicumyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, phenanthrene hydroperoxide, potassium persulfate, sodium persulfate and ammonium persulfate, preferably cumene hydroperoxide and/or potassium persulfate. In the present invention, the reducing agent is selected from reducing agents conventional in the art, for example, the reducing agent is selected from at least one of ferrous sulfate, ferric sodium ethylenediamine tetraacetate, ethylenediamine, triethanolamine, sodium formaldehyde sulfoxylate, preferably at least one of ferrous sulfate, ferric sodium ethylenediamine tetraacetate and sodium formaldehyde sulfoxylate. In the invention, the amount of the initiator is 0.1 to 0.5 weight percent based on the total addition amount of butadiene and acrylonitrile, wherein the amount of the oxidant is 0.05 to 0.2 weight percent, and the amount of the reducing agent is 0.05 to 0.3 weight percent.
In the present invention, the emulsifier is selected from emulsifiers conventional in the art, for example, the emulsifier is selected from at least two of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl diphenyl ether disulfonate, octyl polyoxyethylene ether, potassium oleate, sodium naphthalene sulfonate formaldehyde condensate.
In the present invention, the emulsifier is used in an amount of 1.5 to 6% by weight based on the total amount of butadiene and acrylonitrile added.
Further, the emulsifier is used in an amount of 2 to 4wt% based on the total weight of acrylonitrile and butadiene.
In the present invention, the first molecular weight regulator and the second molecular weight regulator are both selected from alkyl mercaptan molecular weight regulators conventional in the art, for example, the molecular weight regulator is selected from n-dodecyl mercaptan and/or t-dodecyl mercaptan.
In the invention, the first molecular weight regulator is used in an amount of 0.1 to 0.5% by weight and the second molecular weight regulator is used in an amount of 0.1 to 0.5% by weight, based on the total amount of butadiene and acrylonitrile added.
In the present invention, in order to overcome oxygen inhibition, it is preferable that the contacting is performed in an inert atmosphere. The inert atmosphere refers to any gas or gas mixture that does not chemically react with the reactants and reaction products, such as nitrogen, helium, and one or more of the group zero gases of the periodic table. The inert atmosphere may be maintained by introducing into the polymerization system any one of the gases or gas mixtures described above that do not react chemically with the reactants and products.
In the present invention, the amount of the water is not particularly limited as long as the polymerization reaction can be favorably performed, and for example, the water may be used in an amount of 70 to 300 parts by weight based on 100 parts by weight of the total weight of the acrylonitrile and the butadiene. Typically, the water will contain some metal ions, e.g., mg 2+ 、Ca 2+ 、Fe 3+ 、Fe 2+ And so on, it is difficult to completely avoid the presence of metal ions which affect the progress of the polymerization even with the treated deionized water, and therefore, it is preferable that the method of the present invention further comprises adding to the contact reaction system in the step (1)Chelating agents are incorporated. The chelating agent typically has a central ion of one salt-forming group and a complexing group; the central ion and the complexing group are capable of reacting with the metal cation to entrap the metal ion within the chelator, thereby preventing the metal ion from functioning. The kind and amount of the chelating agent are well known to those skilled in the art, and for example, the chelating agent may be selected from one or more of disodium edetate, trisodium edetate and tetrasodium edetate; generally, the chelating agent is used in an amount of 20-65mg based on 100g of water.
In the present invention, in order to promote the stabilization of the emulsion reaction, an electrolyte may be added to the emulsion system in an amount of a kind and an amount well known to those skilled in the art, for example, sodium bicarbonate, potassium carbonate, potassium chloride, etc.
According to the invention, the conditions of the first reaction include: the first reaction temperature is 30-50 ℃, preferably 30-40 ℃ and the reaction time is 0.5-1h.
According to the invention, the conditions of the second reaction include: the second reaction temperature is 5-12 ℃, preferably 5-8 ℃ and the reaction time is 6-15h.
According to the present invention, the conditions of the third reaction include: the third reaction temperature is 5-12 ℃, preferably 5-8 ℃ and the reaction time is 6-18h.
In a third aspect, the present invention provides a nitrile latex prepared by the preparation method provided above.
In the invention, the content of insoluble matters in chlorobenzene in the nitrile latex is less than 1 weight percent.
In the present invention, the nitrile latex is produced by the above method, the dispersion medium is water, and the solid content is not particularly limited, and may be, for example, 1 to 80% by weight, preferably 20 to 60% by weight. In general, the copolymer latex can be directly prepared by the above method, and the solid content is controlled by the addition amount of the monomer, the addition amount of water and the polymerization degree, and the control method is a known method. In addition, a method of dilution with water or concentration with water may be employed, and the concentration method may be a common method of distillation, centrifugation, or the like. According to the application requirements, various auxiliary agents such as a stabilizer, a viscosity regulator, a pH regulator, an agglomerating agent and the like can be added after the copolymer latex provided by the invention is prepared by the method, and the auxiliary agents are reported in the published materials and are not repeated.
In a fourth aspect, the present invention provides a hydrogenated nitrile rubber latex, characterized in that it is obtained by hydrogenation of the above nitrile rubber latex. The hydrogenation method is reported in the published materials and is not repeated. The prepared hydrogenated nitrile rubber latex can maintain the original better oil resistance, and can also obviously improve the weather resistance and chemical resistance of the rubber. The hydrogenated nitrile rubber latex can be added with reinforcing agents, vulcanizing agents, accelerators, anti-aging agents and the like, or other high polymer materials can be used together to form a composition, and the composition can be vulcanized to obtain the hydrogenated nitrile rubber vulcanized rubber, which are all known methods and are reported in the published materials.
In a fifth aspect, the present invention provides a nitrile latex composition, characterized in that it comprises the nitrile latex and/or the hydrogenated nitrile rubber latex described above.
The sixth aspect of the invention provides a nitrile latex vulcanized rubber, which is characterized by being prepared by mixing and vulcanizing the nitrile latex composition.
The present invention will be described in detail by examples.
In the following examples of the present invention,
The combined acrylonitrile amount in the nitrile rubber is tested by nuclear magnetic hydrogen spectrum;
the diameter of the nitrile rubber particles is directly tested by adopting a particle diameter photometer;
the content of insoluble matter in chlorobenzene in the nitrile latex was measured as follows: the latex is flocculated, washed and dried to obtain solid rubber, and the solid rubber is tested by referring to SH/T1050-2014, wherein only toluene in the standard is replaced by chlorobenzene, and other conditions and methods are unchanged;
elongation at break and stretching stress of the vulcanized rubber are measured according to national standard GT/T528-2009;
the oil resistance of the vulcanizate was determined according to method I in SH/T1159-2010.
The raw materials used in the examples and comparative examples are all commercially available.
Example 1
Step 1, sequentially adding 5000g of deionized water, 2g of ethylene diamine tetraacetic acid tetrasodium salt, 120g of acrylonitrile A, 40g of sodium dodecyl diphenyl ether disulfonate and 20g of octyl polyoxyethylene ether-10 into a 20L polymerization kettle, stirring and mixing uniformly, vacuumizing and filling nitrogen for replacement three times, heating to 30 ℃, adding 100g of butadiene, 4g of dicumyl hydroperoxide, 0.8g of ferrous sulfate and 4.8g of formaldehyde sodium sulfoxylate, and reacting at the constant temperature for 1 hour. After the end of the first reaction, a latex A containing nitrile rubber particles A containing a layer A provided by copolymer A was obtained, the average diameter of layer A was 65nm, the latex A bound acrylonitrile was 51.3% by weight and the polymerization conversion was 91.3%.
And 2, cooling the reaction kettle to 5 ℃, and then uniformly adding 450g of acrylonitrile B, 1000g of butadiene B, 6g of tertiary dodecyl mercaptan, 15g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water which are mixed in advance through a diaphragm metering pump at the addition speed of 500g/h. After the addition was completed, the reaction was continued for 7 hours, and after the second reaction was completed, a latex B containing nitrile rubber particles B was obtained, which sequentially contained a layer A provided by copolymer A and a layer B provided by copolymer B in the direction from the center to the outer surface of the nitrile rubber particles B, and the average diameters of the layer A and the layer B were 124nm in the sample test, the latex B was 37.1% by weight in combination with acrylonitrile, and the conversion was 70.2%. The bound acrylonitrile in the copolymer B obtained in this step was 34.3% by weight, calculated according to the formula (1).
And step 3, continuously adding 420g of pre-mixed acrylonitrile C, 1500g of butadiene C, 90g of methacrylic acid, 6g of tertiary dodecyl mercaptan, 15g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water at a constant speed through a diaphragm metering pump, wherein the adding speed is 500g/h. After the addition was completed, the reaction was continued for 2 hours, and after the completion of the third reaction, a nitrile latex containing nitrile rubber particles C was obtained, which was designated NBRL1. Comprising, in order from the center to the outer surface of the nitrile rubber particles C, a layer A provided by a copolymer A, a layer B provided by a copolymer B, and a layer C provided by a copolymer C. The average diameter of layers A, B and C was 161nm, the latex bound acrylonitrile was 29.9wt%, the bound methacrylic acid content was 2.2wt% and the conversion was 67.4% as measured by sampling. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 24.3% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.5wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 7.2X10 4 The insoluble content of chlorobenzene was 0.31% by weight, based on the total weight of rubber particles in the nitrile latex.
Example 2
Step 1, sequentially adding 5000g of deionized water, 2g of ethylene diamine tetraacetic acid tetrasodium salt, 110g of acrylonitrile A, 40g of sodium dodecyl diphenyl ether disulfonate and 15g of octyl polyoxyethylene ether-10 into a 20L polymerization kettle, stirring and mixing uniformly, vacuumizing and filling nitrogen for replacing three times, heating to 30 ℃, adding 120g of butadiene A, 4g of dicumyl hydroperoxide, 0.8g of ferrous sulfate and 4.8g of formaldehyde sodium sulfoxylate, and reacting at constant temperature for 1 hour. After the end of the first reaction, a latex A containing nitrile rubber particles A containing a layer A provided by copolymer A was obtained, the average diameter of layer A was 68nm, the bound acrylonitrile of latex A was 45.6% by weight and the polymerization conversion was 94.1%.
And step 2, cooling the reaction kettle to 5 ℃, and then uniformly adding 430g of acrylonitrile B, 1000g of butadiene B, 6g of tertiary dodecyl mercaptan, 15g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water which are mixed in advance through a diaphragm metering pump, wherein the adding speed is 500g/h. After the addition was completed, the reaction was continued for 7 hours, and after the second reaction was completed, a latex B containing nitrile rubber particles B was obtained, which sequentially contained a layer A provided by copolymer A and a layer B provided by copolymer B in the direction from the center to the outer surface of the nitrile rubber particles B, and the average diameters of the layer A and the layer B were 126nm in total, the latex B was 35.2wt% in combination with acrylonitrile, and the conversion was 66.8%. The bound acrylonitrile in the copolymer B obtained in this step was calculated to be 32.9% by weight according to the formula (1).
And step 3, continuously adding 390g of pre-mixed acrylonitrile C, 1500g of butadiene C, 90g of methacrylic acid, 6g of tertiary dodecyl mercaptan, 17g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water at a constant speed through a diaphragm metering pump, wherein the adding speed is 500g/h. After the addition was completed, the reaction was continued for 2 hours, and after the completion of the third reaction, a nitrile latex containing nitrile rubber particles C was obtained, which was designated NBRL2. Comprising, in order from the center to the outer surface of the nitrile rubber particles C, a layer A provided by a copolymer A, a layer B provided by a copolymer B, and a layer C provided by a copolymer C. The average diameters of layer A, layer B and layer C were 163nm, the latex bound acrylonitrile was 28.5wt%, the bound methacrylic acid content was 2.3wt% and the conversion was 69.6% by sampling test. The bound acrylonitrile content in the copolymer C obtained in this step was 23.7% by weight, calculated according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.5wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 6.7X10 4 The insoluble content of chlorobenzene was 0.44% by weight, based on the total weight of rubber particles in the nitrile latex.
Example 3
Step 1, sequentially adding 5000g of deionized water, 2g of ethylene diamine tetraacetic acid tetrasodium salt, 90g of acrylonitrile A, 40g of sodium dodecyl diphenyl ether disulfonate and 22g of octyl polyoxyethylene ether-10 into a 20L polymerization kettle, stirring and mixing uniformly, vacuumizing and filling nitrogen for replacing three times, heating to 40 ℃, adding 120g of butadiene A, 3.8g of dicumyl hydroperoxide, 0.8g of ferrous sulfate and 4.8g of formaldehyde sodium sulfoxylate, and reacting at constant temperature for 1 hour. After the end of the first reaction, a latex A containing nitrile rubber particles A containing a layer A provided by copolymer A was obtained, the average diameter of layer A was 61nm, the latex A bound acrylonitrile was 41.1% by weight and the polymerization conversion was 98.7%.
And 2, cooling the reaction kettle to 5 ℃, and then uniformly adding 400g of acrylonitrile B, 1000g of butadiene B, 6g of tertiary dodecyl mercaptan, 12g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water which are mixed in advance through a diaphragm metering pump at the addition speed of 500g/h. After the addition was completed, the reaction was continued for 7 hours, and after the second reaction was completed, a latex B containing nitrile rubber particles B was obtained, which sequentially included a layer A provided by the copolymer A and a layer B provided by the copolymer B in the direction from the center to the outer surface of the nitrile rubber particles B, the sum of the average diameters of the layer A and the layer B was 120nm, the bound acrylonitrile of the latex B was 32.3wt%, and the conversion was 71.5%. The bound acrylonitrile in the copolymer B obtained in this step was calculated to be 30.5% by weight according to the formula (1).
And step 3, continuously adding 325g of pre-mixed acrylonitrile C, 1500g of butadiene C, 85g of methacrylic acid, 6g of tertiary dodecyl mercaptan, 11g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water at a constant speed through a diaphragm metering pump, wherein the adding speed is 500g/h. After the addition was completed, the reaction was continued for 2 hours, and after the completion of the third reaction, a nitrile latex containing nitrile rubber particles C was obtained, which was designated NBRL3. Comprising, in order from the center to the outer surface of the nitrile rubber particles C, a layer A provided by a copolymer A, a layer B provided by a copolymer B, and a layer C provided by a copolymer C. The average diameters of layer A, layer B and layer C were combined at 159nm, the latex bound acrylonitrile at 25.6wt%, the bound methacrylic acid content at 2.1wt% and the conversion at 66.3% by sampling test. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 20.1% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.5wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 5.6X10 4 The insoluble content of chlorobenzene was 0.74% by weight, based on the total weight of rubber particles in the nitrile latex.
Example 4
Step 1, sequentially adding 5000g of deionized water, 2g of ethylene diamine tetraacetic acid tetrasodium salt, 85g of acrylonitrile A, 40g of sodium dodecyl diphenyl ether disulfonate and 24g of octyl polyoxyethylene ether-10 into a 20L polymerization kettle, stirring and mixing uniformly, vacuumizing and filling nitrogen for replacing three times, heating to 50 ℃, adding 120g of butadiene A, 4g of dicumyl hydroperoxide, 0.8g of ferrous sulfate and 4.8g of formaldehyde sodium sulfoxylate, and reacting at constant temperature for 1 hour. After the end of the first reaction, a latex A is obtained which comprises nitrile rubber particles A containing a layer A provided by copolymer A, the average diameter of layer A being 65nm, the latex A bound acrylonitrile being 40.2% by weight and the polymerization conversion being 99%.
And step 2, cooling the reaction kettle to 12 ℃, and then uniformly adding 430g of acrylonitrile B, 1000g of butadiene B, 6g of tertiary dodecyl mercaptan, 12g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water which are mixed in advance through a diaphragm metering pump, wherein the adding speed is 500g/h. After the addition was completed, the reaction was continued for 7 hours, and after the second reaction was completed, a latex B containing nitrile rubber particles B was obtained, which sequentially contained a layer A provided by copolymer A and a layer B provided by copolymer B in the direction from the center to the outer surface of the nitrile rubber particles B, and the average diameters of the layer A and the layer B were 138nm in the sample test, the latex B was 33.3% by weight in combination with acrylonitrile, and the conversion was 81.3%. The bound acrylonitrile in the copolymer B obtained in this step was calculated to be 32.1% by weight according to the formula (1).
And step 3, continuously adding 460g of pre-mixed acrylonitrile C, 1500g of butadiene C, 90g of methacrylic acid, 6g of tertiary dodecyl mercaptan, 15g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water at a constant speed through a diaphragm metering pump, wherein the adding speed is 500g/h. After the addition was completed, the reaction was continued for 2 hours, and after the completion of the third reaction, a nitrile latex containing nitrile rubber particles C was obtained, which was designated NBRL4. Comprising, in order from the center to the outer surface of the nitrile rubber particles C, a layer A provided by a copolymer A, a layer B provided by a copolymer B, and a layer C provided by a copolymer C. The average diameters of layer A, layer B and layer C were combined to be 181nm, the latex bound acrylonitrile was 26.9wt%, the bound methacrylic acid content was 2.4wt% and the conversion was 89.4% by sampling test. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 22.5% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.5wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 6.5X10 4 The insoluble content of chlorobenzene was 0.91% by weight, based on the total weight of rubber particles in the nitrile latex.
Example 5
Step 1, sequentially adding 5000g of deionized water, 2g of ethylene diamine tetraacetic acid tetrasodium salt, 110g of acrylonitrile A, 60g of sodium dodecyl diphenyl ether disulfonate and 20g of octyl polyoxyethylene ether-10 into a 20L polymerization kettle, stirring and mixing uniformly, vacuumizing and filling nitrogen for replacing three times, heating to 30 ℃, adding 120g of butadiene A, 4g of dicumyl hydroperoxide, 0.8g of ferrous sulfate and 4.8g of formaldehyde sodium sulfoxylate, and reacting at constant temperature for 1 hour. After the end of the first reaction, a latex A is obtained which comprises nitrile rubber particles A containing a layer A provided by copolymer A, the average diameter of layer A being 56nm, the latex A bound acrylonitrile being 46.8% by weight and the polymerization conversion being 99.2%.
And step 2, cooling the reaction kettle to 5 ℃, and then uniformly adding 430g of acrylonitrile B, 1000g of butadiene B, 6g of tertiary dodecyl mercaptan, 25g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water which are mixed in advance through a diaphragm metering pump, wherein the adding speed is 500g/h. After the addition was completed, the reaction was continued for 7 hours, and after the second reaction was completed, a latex B containing nitrile rubber particles B was obtained, which sequentially contained a layer A provided by copolymer A and a layer B provided by copolymer B in the direction from the center to the outer surface of the nitrile rubber particles B, and the average diameters of the layer A and the layer B were 103nm in the sample test, the latex B was 33.6wt% in combination with acrylonitrile, and the conversion was 78.2%. The bound acrylonitrile in the copolymer B obtained in this step was calculated to be 30.9% by weight according to the formula (1).
And step 3, continuously adding 390g of pre-mixed acrylonitrile C, 1500g of butadiene C, 90g of methacrylic acid, 6g of tertiary dodecyl mercaptan, 25g of sodium dodecyl diphenyl ether disulfonate and 1000g of deionized water at a constant speed through a diaphragm metering pump, wherein the adding speed is 500g/h. After the addition was completed, the reaction was continued for 2 hours, and after the completion of the third reaction, a nitrile latex containing nitrile rubber particles C was obtained, which was designated NBRL5. Comprising, in order from the center to the outer surface of the nitrile rubber particles C, a layer A provided by a copolymer A, a layer B provided by a copolymer B, and a layer C provided by a copolymer C. The average diameters of layer A, layer B and layer C were 147nm, the latex bound acrylonitrile was 26.3wt%, the bound methacrylic acid content was 2.4wt% and the conversion was 83.2% by sampling test. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 20.9% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 3.7wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.5wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 8.1X10 4 By rubber particles in nitrile latexThe insoluble content of chlorobenzene was 0.87wt% based on the total weight of the seed.
Example 6
Step 1, the same as in example 2.
Step 2, except that the reaction time was prolonged from 8 hours to 15 hours, was conducted in the same manner as in example 2, and the sample was taken after the completion of the second reaction, the sum of the average diameters of the layer A and the layer B was 137nm, the bound acrylonitrile of the latex B was 32.6wt%, and the conversion was 86.7%. The bound acrylonitrile in the copolymer B obtained in this step was calculated to be 30.4% by weight according to the formula (1).
Step 3 the procedure of example 2 was followed except that the reaction time was prolonged from 10 hours to 18 hours. After the end of the third reaction, a nitrile latex was obtained, designated NBRL6. The average diameters of layer A, layer B and layer C were 182nm, the latex bound acrylonitrile was 26.1wt%, the bound methacrylic acid content was 2.4wt% and the conversion was 86.3% as measured by sampling. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 20.8% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.5wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 7.8X10 4 The insoluble content of chlorobenzene was 0.76% by weight, based on the total weight of rubber particles in the nitrile latex.
Example 7
Step 1 was the same as in example 2 except that the reaction time was changed from 1 hour to 0.5 hour. After the end of the first reaction, the sample was taken and tested, layer A having an average diameter of 52nm, latex C having 42.8% by weight of bound acrylonitrile and a polymerization conversion of 33.7%.
Step 2 was the same as in example 2 except that the reaction time was changed from 8 hours to 6 hours. After the end of the second reaction, the sample was taken and tested, the sum of the average diameters of layer A and layer B being 108nm, latex B having 34.7% by weight of bound acrylonitrile and a conversion of 46.6%. The bound acrylonitrile in the copolymer B obtained in this step was 33.8% by weight, calculated according to the formula (1).
Step 3, example 2 was repeated except that the reaction time was changed from 10 hours to 6 hours. After the end of the third reaction, a nitrile latex was obtained, designated NBRL7. The average diameters of layer A, layer B and layer C were 154nm, the latex bound acrylonitrile was 26.9wt%, the bound methacrylic acid content was 2.1wt% and the conversion was 51.2% by sampling test. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 22.4% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.5wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 4.4X10 4 The insoluble content in chlorobenzene was 0.41% by weight, based on the total weight of rubber particles in the nitrile latex.
Example 8
Step 1, the same as in example 2.
Step 2, the same as in example 2.
Step 3 the same as in example 2 except that 90g of methacrylic acid was added to 150g of methacrylic acid. After the end of the third reaction, a nitrile latex was obtained, designated NBRL8. The average diameters of layer A, layer B and layer C were 167nm, the latex was 27.1wt% with acrylonitrile, 3.9wt% with methacrylic acid, and the conversion was 71.3% as measured by sampling. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 21.4% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 4.2wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 6.7X10 4 The insoluble content of chlorobenzene was 0.44% by weight, based on the total weight of rubber particles in the nitrile latex.
Comparative example 1
The procedure and the amounts of the materials added were the same as in example 2, except that the reaction temperatures in the first, second and third steps were 50 ℃.
After the end of the first reaction, the sample was taken and tested, layer A had an average diameter of 67nm, latex A bound acrylonitrile of 47.5wt% and a polymerization conversion of 98.8%.
After the end of the second reaction, the sample was taken and tested, the sum of the average diameters of layer A and layer B being 129nm, latex B incorporating 31.1% by weight acrylonitrile and the conversion being 98.7%. The bound acrylonitrile in the copolymer B obtained in this step was 28.5% by weight, calculated according to the formula (1).
After the end of the third reaction, a nitrile latex was obtained, designated NBRLD1. The average diameter of layers A, B and C was 191nm, the latex bound acrylonitrile was 24.1wt%, the bound methacrylic acid content was 2.4wt% and the conversion was 99.5% as measured by sampling. The bound acrylonitrile content of the copolymer C obtained in this step was 18wtw% calculated according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
The number average molecular weight of the finally obtained latex, the nitrile latex was 8.1X10 4 The insoluble content of chlorobenzene was 5.74% by weight, based on the total weight of rubber particles in the nitrile latex.
Comparative example 2
The procedure and the amounts of the materials added were the same as in example 2, except that the reaction temperatures in the first, second and third steps were 5 ℃.
After the end of the first reaction, the sample was taken and tested, layer A having an average diameter of 43nm, latex A having a bound acrylonitrile of 43.7wt% and a polymerization conversion of 26.2%.
After the end of the second reaction, the sample was taken and tested, the sum of the average diameters of layer A and layer B being 72nm, the latex B bound acrylonitrile 36.6wt% and the conversion 48.8%. The bound acrylonitrile in the copolymer B obtained in this step was calculated to be 36.1% by weight according to the formula (1).
After the end of the third reaction, a nitrile latex was obtained, designated NBRLD2. The average diameter of layer A, layer B and layer C was 94nm, the latex bound acrylonitrile was 35.4wt%, the bound methacrylic acid content was 2wt% and the conversion was 55.6% by sampling test. The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
The bound acrylonitrile content in the copolymer C obtained in this step was 34.7% by weight, calculated according to the formula (2).
The number average molecular weight of the finally obtained latex, the nitrile latex was 4.3X10 4 The insoluble content of chlorobenzene was 0.31% by weight, based on the total weight of rubber particles in the nitrile latex.
Comparative example 3
Step 1 was the same as in example 2 except that the amount of acrylonitrile added was changed from 110g to 75 g. After the end of the first reaction, the sample was taken and tested, layer A having an average diameter of 65nm, latex A having 36.2% by weight of bound acrylonitrile and a polymerization conversion of 90.6%.
Step 2, the same as in example 2. After the end of the second reaction, the sample was taken and tested, the sum of the average diameters of layer A and layer B being 131nm, the latex B bound acrylonitrile being 33.4% by weight and the conversion being 72.5%. The bound acrylonitrile in the copolymer B obtained in this step was calculated to be 32.9% by weight according to the formula (1).
Step 3, same as in example 2. After the end of the third reaction, a nitrile latex was obtained, designated NBRLD3. The average diameters of layer A, layer B and layer C were 167nm, the latex bound acrylonitrile was 26.1wt%, the bound methacrylic acid content was 2.3wt% and the conversion was 62.4% as measured by sampling. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 19.8% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.6wt%, based on the total weight of butadiene and acrylonitrile. The number average molecular weight of the finally obtained latex, the nitrile latex was 4.6X10 4 The insoluble content in chlorobenzene was 0.51% by weight, based on the total weight of rubber particles in the nitrile latex.
Comparative example 4
The procedure and the amounts of each charge were the same as in example 2, except that methacrylic acid was added in the second step instead.
After the second reaction was completed, the sample was taken and the average diameter of the layers A and B was 128nm, the copolymer was 34.1wt% with acrylonitrile and 4.6wt% with methacrylic acid, and the conversion was 69.4%. The bound acrylonitrile in the copolymer B obtained in this step was 31.5% by weight, calculated according to the formula (1).
After the end of the third reaction, a nitrile latex was obtained, designated NBRLD4. The average diameters of layer A, layer B and layer C were 165nm, the latex bound acrylonitrile was 26.6wt%, the bound methacrylic acid content was 2.5wt% and the conversion was 72.4% as measured by sampling. The bound acrylonitrile content in the copolymer C obtained in this step was calculated to be 21.4% by weight according to the formula (2). The combined acrylonitrile content of copolymer A, copolymer B and copolymer C is shown in Table 1, the layer A diameter, layer A+layer B diameter and layer A+layer B+layer C diameter and the number average molecular weight of the nitrile latex are shown in Table 1.
In the above reaction, the amount of the oxidizing agent was 0.11wt%, the amount of the reducing agent was 0.16wt%, the amount of the emulsifying agent was 2.5wt%, the amount of the first molecular weight regulator was 0.17wt%, the amount of the second molecular weight regulator was 0.17wt%, and the amount of the ethylenically unsaturated carboxylic acid was 2.5wt%, based on the total weight of butadiene and acrylonitrile. Finally obtainedLatex, number average molecular weight of nitrile latex is 6.1X10 4 The insoluble content of chlorobenzene was 0.57% by weight, based on the total weight of rubber particles in the nitrile latex.
TABLE 1
Test case
Preparation of vulcanized rubber
The latices obtained in examples and comparative examples were concentrated or diluted to a solid content of 40wt%, and then pH was adjusted to 9 with aqueous ammonia, followed by mixing according to the formulation, and vulcanization was carried out at 110 to 120℃for 20 minutes to obtain a film, and the elongation at break, elongation stress and oil resistance of the vulcanized rubber were measured and the results are shown in Table 2.
The formula is as follows: 100 parts of latex, 2 parts of zinc oxide, 0.5 part of sulfur, 0.3 part of accelerator BZ, 0.5 part of anti-aging agent and 2 parts of titanium dioxide.
TABLE 2
As can be seen from tables 1 and 2, the nitrile latices provided in examples 1-8 of the present invention combine a lower degree of swelling, a higher tensile stress and a higher elongation at break. Therefore, the nitrile latex provided by the invention has excellent oil resistance and mechanical property, and can meet the application requirements of thin gloves.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (15)
1. A nitrile latex, characterized by comprising at least three layers of structures of layer a, layer B and layer C in sequence along the direction from the center to the outer surface of rubber particles in the nitrile latex;
wherein the layer a is provided by a copolymer a having a bound acrylonitrile content of 40wt% or more based on the total weight of the copolymer a;
the layer B is provided by a copolymer B, and the content of bound acrylonitrile is 30-35wt% based on the total weight of the copolymer B;
the layer C is provided by a copolymer C having a bound acrylonitrile content of 20 to 25 wt.%, based on the total weight of the copolymer C.
2. The nitrile latex according to claim 1, wherein the combined acrylonitrile content is greater than or equal to 45wt%, preferably greater than or equal to 50wt%, based on the total weight of copolymer a.
3. The nitrile latex of claim 1, wherein the layer a has a diameter of 50-90nm, the sum of the diameters of the layer a and the layer B is 100-140nm, and the sum of the diameters of the layer a, the layer B and the layer C is 150-200nm.
4. The nitrile latex according to any of claims 1-3, wherein the level of insolubles in chlorobenzene is less than 1 wt.%, based on the total weight of rubber particles in the nitrile latex.
5. The nitrile latex according to any of claims 1-4, wherein copolymer C further comprises structural units provided by ethylenically unsaturated carboxylic acids;
preferably, the content of structural units provided by the ethylenically unsaturated carboxylic acid is from 1 to 5% by weight, based on the total weight of particles in the nitrile latex.
6. A method for preparing a nitrile latex, which is characterized by comprising the following steps:
s1, carrying out a first reaction of acrylonitrile A, butadiene A and an emulsifier in water in the presence of an initiator to obtain a latex A comprising nitrile rubber particles A containing a layer A provided by a copolymer A;
s2, adding acrylonitrile B, butadiene B and a first molecular weight regulator into the latex A for a second reaction to obtain latex B containing nitrile rubber particles B, wherein the latex B sequentially comprises a layer A provided by a copolymer A and a layer B provided by the copolymer B along the direction from the center of the nitrile rubber particles B to the outer surface;
S3, adding acrylonitrile C, butadiene C and a second molecular weight regulator into the latex B for a third reaction to obtain a nitrile latex containing nitrile rubber particles C, wherein the nitrile latex sequentially comprises a layer A provided by a copolymer A, a layer B provided by a copolymer B and a layer C provided by the copolymer C along the direction from the center of the nitrile rubber particles C to the outer surface;
wherein the conditions of the first reaction are such that the copolymer A obtained in the first reaction has a bound acrylonitrile content of 40wt% or more based on the total weight of the copolymer A, and the diameter of the nitrile rubber particles A in the latex A is 50 to 90nm;
the conditions of the second reaction are such that, in the second reaction, a copolymer B is obtained, the bound acrylonitrile content being from 30 to 35% by weight, based on the total weight of the copolymer B, the diameter of the nitrile rubber particles B in the latex B being from 100 to 140nm;
the conditions of the third reaction are such that, in the third reaction, a copolymer C is obtained, the bound acrylonitrile content being 20 to 25% by weight, based on the total weight of the copolymer C, and the diameter of the nitrile rubber particles C in the latex C being 150 to 200nm.
7. The production method according to claim 6, wherein in the first reaction, the acrylonitrile A is used in an amount of 41wt% or more, preferably 41 to 55wt% based on acrylonitrile A and butadiene A;
In the second reaction, the amount of acrylonitrile B is 28 to 32 weight percent based on the total weight of the acrylonitrile B and the butadiene B;
in the third reaction, the acrylonitrile C is used in an amount of 17 to 24wt% based on the total weight of the acrylonitrile C and the butadiene C.
8. The production method according to claim 6 or 7, further comprising adding a vinyl unsaturated carboxylic acid in step S3;
preferably, in the third reaction, the ethylenically unsaturated carboxylic acid is used in an amount of 1 to 5wt% based on the total weight of all acrylonitrile and butadiene.
9. The production process according to any one of claims 6 to 8, wherein the initiator is used in an amount of 0.1 to 0.5% by weight based on the total weight of acrylonitrile and butadiene;
the amount of the emulsifier is 1.5-6wt% based on the total weight of the acrylonitrile and the butadiene;
the first molecular weight regulator is used in an amount of 0.1 to 0.5wt% and the second molecular weight regulator is used in an amount of 0.1 to 0.5wt% based on the total weight of acrylonitrile and butadiene.
10. The production method according to any one of claims 6 to 9, wherein the conditions of the first reaction include: the first reaction temperature is 30-50 ℃ and the reaction time is 0.5-1h;
The conditions of the second reaction include: the second reaction temperature is 5-12 ℃ and the reaction time is 6-12h;
the conditions of the third reaction include: the third reaction temperature is 5-12 ℃, and the reaction time is 6-18h.
11. The production method according to any one of claims 6 to 10, wherein the first molecular weight modifier and the second molecular weight modifier are each independently selected from n-dodecyl mercaptan and/or t-dodecyl mercaptan;
preferably, the emulsifier is selected from at least two of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl diphenyl ether disulfonate, octyl polyoxyethylene ether, potassium oleate, and sodium naphthalene sulfonate formaldehyde condensate.
12. A nitrile latex produced by the production process according to any one of claims 6 to 11.
13. A hydrogenated nitrile rubber latex, characterized in that it is obtained by hydrogenation of the nitrile rubber latex according to any one of claims 1 to 5 and 11.
14. A nitrile latex composition, characterized in that it comprises the nitrile latex according to any one of claims 1 to 5 and 11 and/or the hydrogenated nitrile rubber latex according to claim 13.
15. A nitrile latex vulcanizate, wherein the nitrile latex vulcanizate is prepared from the nitrile latex composition of claim 14 by mixing and vulcanization.
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| CN116003711A (en) * | 2021-10-21 | 2023-04-25 | 中国石油化工股份有限公司 | Nitrile rubber and preparation method thereof, hydrogenated nitrile rubber, nitrile rubber composition and nitrile rubber vulcanized rubber |
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| CN116003711A (en) * | 2021-10-21 | 2023-04-25 | 中国石油化工股份有限公司 | Nitrile rubber and preparation method thereof, hydrogenated nitrile rubber, nitrile rubber composition and nitrile rubber vulcanized rubber |
| CN116003711B (en) * | 2021-10-21 | 2023-06-20 | 中国石油化工股份有限公司 | Nitrile rubber and preparation method thereof, hydrogenated nitrile rubber, nitrile rubber composition and nitrile rubber vulcanized rubber |
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