CN113024735A - Valeronitrile latex and preparation method thereof - Google Patents
Valeronitrile latex and preparation method thereof Download PDFInfo
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- CN113024735A CN113024735A CN202110228269.5A CN202110228269A CN113024735A CN 113024735 A CN113024735 A CN 113024735A CN 202110228269 A CN202110228269 A CN 202110228269A CN 113024735 A CN113024735 A CN 113024735A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F253/00—Macromolecular compounds obtained by polymerising monomers on to natural rubbers or derivatives thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
- C08C1/00—Treatment of rubber latex
- C08C1/02—Chemical or physical treatment of rubber latex before or during concentration
- C08C1/04—Purifying; Deproteinising
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2307/00—Characterised by the use of natural rubber
- C08J2307/02—Latex
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2351/00—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
- C08J2351/04—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers grafted on to rubbers
Abstract
The invention discloses valeronitrile latex and a preparation method thereof. The valeronitrile latex is acrylonitrile/natural rubber graft copolymer emulsion which is prepared by graft copolymerization of deproteinized natural latex, a diluent, an emulsifier, a diffusant, a pH value buffering agent, an acrylonitrile monomer, a second comonomer, a coupling agent and an oxidation-reduction initiator. The copolymer latex provided by the invention has good vulcanization performance, film forming property and physical strength, and has the performance advantages of natural latex and butyronitrile latex as the raw materials of dipping products, thereby further widening the application range of the natural latex in the medical and health fields of medical gloves, protective film materials and the like.
Description
Technical Field
The invention relates to a processing method of acrylonitrile modified natural latex, in particular to an acrylonitrile/natural rubber graft copolymer and a preparation method thereof, namely valeronitrile latex and a preparation method thereof, belonging to the technical field of rubber processing.
Background
The natural latex is a renewable resource with environment-friendly sources, and the unique stereoregularity in a molecular chain and the entanglement of large chain molecules caused by the free rotation degree of a methylene C-C bond endow the natural latex with excellent cohesive force, excellent film forming property, high adhesion elasticity, barrier property to gas and liquid and the like, so that the natural latex becomes an irreplaceable film forming material at present. However, natural latex contains proteins which can cause allergy to human body, so that the application range of the natural latex as biomedical materials is limited. Fresh natural latex is derived from the rubber tree and contains about 30% of rubber component (cis 1, 4-polyisoprene), 5% of non-rubber material (2% protein therein) and skim latex dispersed in water. The surface of the emulsion particle is coated by a continuous monolayer of negatively charged phospholipid/protein complexes, which can maintain the stability of the colloid. There are 14 proteins (Hev b1-14) in NR latex which are recognized as sensitizable pathogens by the International immunology Association. Wherein, Hev b1 existing on the surface with large particle size and Hev b3 existing on the surface with smaller particle size are main sensitizing proteins. In addition, these non-rubber components such as proteins are liable to absorb moisture, mold, generate heat and conduct electricity; the viscosity of the latex is increased due to protein aggregation, and the latex is hardened and the storage effect is damaged due to spontaneous crosslinking of amino acid and some abnormal groups; these proteins are also free radical scavengers, chemically active, interfering with the further chemical modification of the rubber, e.g. the molecular weight of the NR grafted chains containing the proteins is only around 2000. If these non-gel components such as proteins can be removed, the reactive centers are limited to the double bond sites of the cis-1, 4-isoprene units and the sites where the allyl groups are located, and the reactive centers can be selected according to the need to introduce various functional groups into desired positions.
The natural rubber has excellent performance incomparable with synthetic rubber, and the non-rubber components such as protein and the like attached to the surface layer of the rubber particles are the key for supporting the performance of the rubber, can form a nano matrix structure together with the rubber particles to form a network structure, promote intermolecular crosslinking, play an important role in strain-induced crystallization before and after vulcanization, and improve stress and elastic modulus. The natural latex has excellent comprehensive performance, good process film forming performance, high wet gel strength and easy vulcanization, and the products of the natural latex comprise dipping products, extruded products, sponge products, casting products and the like, and have the characteristics of high elasticity, high strength, high elongation, small creep and the like. However, the natural rubber products have poor oil resistance, aging resistance, acid and alkali resistance, heat resistance, weather resistance and the like and poor air tightness, and compared with the carboxyl butyronitrile latex products, the carboxyl butyronitrile latex products have better oil resistance, aging resistance, acid and alkali resistance, heat resistance, weather resistance, puncture resistance and air tightness than the natural latex products and have no protein allergy. Although carboxylated nitrile latex has an appearance similar to natural latex and a gelling process similar to natural latex, it is obtained by chemical synthesis, the composition of which not only contains a relatively large amount of emulsifier, but also the molecular weight of the nitrile copolymer is much lower than that of the rubber in natural latex, resulting in a great difference in technological characteristics from natural latex, such as in the manufacture of gloves by dipping: 1) the gum dipping speed is faster than that of natural gum, otherwise, transverse cracks can occur; 2) the leaching before the wet gel film is necessary, the leaching time is longer than that of the natural latex, the water temperature is lower than that of the natural latex, the wet gel shrinkage is large due to the high temperature, and the finger fork is easy to crack. If leaching is insufficient, the adhesive film contains more emulsifier, which not only affects drying and vulcanization and reduces the comprehensive performance of the product, but also can cause the surface of the product to be sticky after storage because the residual emulsifier in the glove can be separated out; 3) the wet gel strength of the carboxylated nitrile latex is weaker than that of natural latex, and because the particles are finer, the film is denser than that of the natural latex after film formation, and moisture is not easy to discharge, so that the low-temperature drying is carried out for a longer time in the early stage of vulcanization, and the later vulcanization is facilitated. If the initial temperature is higher, the film shrinks too fast, which may cause cracks in the film.
The preparation method of the carboxylic acrylonitrile butadiene latex mainly uses butadiene, acrylonitrile, acrylic acid or methacrylic acid monomers as main materials, and obtains the carboxylic acrylonitrile butadiene latex by adjusting the reaction conditions such as the types and the dosage of an emulsifier, a regulator and an initiator, the addition mode, the reaction temperature, the reaction time, the stirring speed and the like. The butadiene as the reaction raw material belongs to a flammable and explosive gas-liquid mixture, a high-pressure closed environment is required in the whole polymerization reaction process, the reaction conditions are harsh, and equipment matching and production control are complex.
According to the invention, acrylonitrile is grafted to a rubber chain of natural latex under a proper condition, so that valeronitrile latex (natural rubber/acrylonitrile graft copolymer latex) with comprehensive performance superior to that of the natural latex and the acrylonitrile-butadiene latex is obtained, the rubber chain keeps the original high molecular weight, and the latex has the advantages of high elasticity, low creep deformation and other natural rubbers; meanwhile, acrylonitrile introduced by grafting endows the latex with excellent puncture resistance, air tightness, oil resistance, aging resistance, acid and alkali resistance, heat resistance, weather resistance and other properties. Particularly, the use of butadiene gas with high risk in the preparation process is avoided, and the natural latex is subjected to deproteinization and purification treatment to remove non-gum substances such as protein, phospholipid, polysaccharide and the like, and is replaced by the emulsifier with better stability. Under the condition of eliminating the interference of protein, phospholipid and the like on polymerization reaction, the reaction active center of the rubber latex is limited to two positions of double bond and allyl of cis-1, 4-isoprene unit, acrylonitrile monomer is easy to graft and modify, and the whole reaction process can be carried out under the mild condition of normal pressure, so that the operation is easy and controllable. The bonding law of acrylonitrile, the fluid morphology of the obtained latex and the physical properties of the latex are controlled by introducing a second monomer, changing an emulsifier, a redox reaction initiator, adjusting the pH value and the like. The valeronitrile latex obtained by the method is well compatible with butyronitrile latex, deproteinized natural latex and natural latex respectively. The valeronitrile latex is respectively blended with butyronitrile latex, deproteinized natural latex and then vulcanized, and products of the valeronitrile latex, including dipped products, extruded products, sponge products and casting products, have the characteristics of better elasticity, strength, elongation and the like.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the acrylonitrile/natural rubber graft copolymer and the preparation method thereof are provided to improve the film forming uniformity of the natural rubber latex and the characteristics of oil resistance, aging resistance, acid and alkali resistance, heat resistance, weather resistance, puncture resistance, air tightness and the like which are needed and difficult to be possessed by the natural rubber, solve the problem of compatibility of the obtained latex with the acrylonitrile-butadiene latex, deproteinized natural rubber latex and the natural rubber latex, and provide alternative materials for the doping modification of the acrylonitrile-butadiene latex, the deproteinized natural rubber latex and the natural rubber latex.
In order to solve the problems, the invention adopts the following technical scheme:
the valeronitrile latex is characterized in that the valeronitrile latex is acrylonitrile/natural rubber graft copolymer emulsion which is prepared by graft copolymerization of deproteinized natural latex, a diluent, an emulsifier, a diffusant, a pH value buffering agent, an acrylonitrile monomer, a second comonomer, a coupling agent and an oxidation-reduction initiator.
Preferably, the deproteinized natural latex is obtained by treating any one or more of field latex obtained from gum solution of natural rubber tree or concentrated latex stored in ammonia by a natural latex deproteinization method; the mass content of the rubber dry rubber in the deproteinized natural latex is 5-60%, and the protein content of the deproteinized natural latex is lower than 110 mu g/g (ASTM D5712).
Preferably, the diluent is pure water or ammonia water with the mass concentration of 1-5%, and the adding amount of the diluent is 20-500% of the mass of rubber dry rubber in the deproteinized natural latex.
Preferably, the addition amount of the acrylonitrile monomer is 1-80% of the mass of the rubber dry rubber in the deproteinized natural latex.
Preferably, the second comonomer is at least one of acrylic acid, methacrylic acid, acrylamide, methacrylamide, styrene, N-vinylpyrrolidone, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and glycidyl methacrylate, and is added in an amount of not more than 80% by mass of rubber dry gum in the deproteinized natural latex.
Preferably, the emulsifier is casein, chitosan oligosaccharide, water-soluble chitosan, carboxylated chitosan, mucopolysaccharide, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate of flaveria, carbomer resin, potato starch, corn starch, glutinous rice starch, carbomer, flaxseed gum, konjac gum, caprolactam, polyglutamic acid, cyclodextrin, betaine, carbomer, tween, span, lanolin, agar, oleic acid, ammonium oleate, triethanolamine, polyethyleneimine, alkyldimethylamine oxide, cetyl trimethyl ammonium bromide, polyhydroxybutyrate, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polyoxyethylene lauryl ether, polyoxyethylene octylphenol ether-10, polyglycerol glycidyl ether, a monthly silicate, a polyoxyalkylene ester surfactant, a polyol fatty acid ester surfactant, a polysaccharide, a chitosan, a mucopolysaccharide, a carboxymethyl cellulose, a carboxyl methyl cellulose, a hydroxyethyl cellulose, hydroxypropyl cellulose, a cellulose acetate, a polyethylene glycol ester surfactant, a polyoxyethylene octylphenol ether-10, a polyglycerol glycidyl ether, a lauric acid, a polyoxyethylene ester surfactant, a, Polyoxyalkylene ether surfactant, dodecyltrimethylammonium bromide, alkylbenzenesulfonate, alkylsulfonate, naphthalenesulfonate, diisooctylsulfosuccinate, diphenylethersulfonate, benzenesulfonate, naphthalenesulfonate, alkylsulfonate, dialkylsulfosuccinate, alkylsulfate, polyoxyalkylene distyrenated phenol sulfate, polyoxyalkylene sulfate, trisstyrenated phenol sulfate, polyoxyalkylene phenyl ether sulfate, polyoxyalkylene alkyl phenyl ether sulfate, polyoxyalkylene triphenylethylenated phenol sulfate, polyoxyalkylene diphenylethylenated phenol sulfate, alkylamine derivative, and quaternary ammonium salt polymer, in an amount of 0.1 to 10% by mass based on the mass of the rubber dry mass in the deproteinized natural latex.
Preferably, the diffusant is at least one of cyclohexane, solvent gasoline, heptane, benzene, xylene and petroleum ether, and the addition amount of the diffusant is not more than 20% of the mass of rubber dry rubber in the deproteinized natural latex.
Preferably, the coupling agent is at least one of N, N-methylenebisacrylamide, tetraethylene glycol dimethacrylate, divinylbenzene, triallylisocyanurate and diallyl phthalate, and is added in an amount of not more than 10% by mass of the rubber dry mass in the deproteinized natural rubber latex.
Preferably, the oxidant in the redox initiator is at least one of hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, persulfate, dibenzoyl peroxide and potassium permanganate, and the addition amount of the oxidant is 0.01-10% of the mass of rubber dry glue in the deproteinized natural latex; the reducing agent in the redox initiator is at least one of sodium bisulfite, sodium thiosulfate, tetraethylenepentamine, ethylenediamine, glucose, N-dimethylaniline, thiourea and ascorbic acid, and the adding amount of the reducing agent is 0.01-10% of the mass of the rubber dry glue in the deproteinized natural latex.
Preferably, the pH buffer is at least one of lactic acid, acetic acid, succinic acid, citric acid, monopotassium phosphate, dipotassium phosphate, monosodium phosphate, disodium phosphate, sodium phosphate, potassium acetate, sodium hydroxide, ammonia water, potassium hydroxide, sodium carbonate and sodium bicarbonate, and the addition amount of the pH buffer is 0.0001-10% of the mass of rubber dry glue in the deproteinized natural latex.
The invention also provides a preparation method of the valeronitrile latex, which is characterized in that deproteinized purification treatment is carried out on natural latex to obtain deproteinized natural latex, then diluent is added to dilute the natural latex, and emulsifier is added to prepare natural latex mixed liquor after the natural latex is uniformly stirred; adding a pH value buffering agent to set the pH value of the natural latex mixed solution within a range of 3.5-5.5 or 8-11; adding a second comonomer, an acrylonitrile monomer and a redox initiator to obtain a polymerization reaction system, wherein the solid content is controlled to be 15-50 wt%, the nitrogen protection penetrates through the whole reaction process, the reaction temperature is controlled to be 10-85 ℃, and the reaction time is controlled to be 0.5-30hr, so that the natural rubber/acrylonitrile graft copolymer emulsion with the acrylonitrile grafting rate of 1-70%, namely valeronitrile latex is prepared.
The invention also provides application of the valeronitrile latex, which is characterized in that the valeronitrile latex is added into deproteinized natural latex, the adding amount of the valeronitrile latex is 20-500% of the mass of rubber dry rubber in the deproteinized natural latex, and the valeronitrile latex and the deproteinized natural latex are uniformly mixed to prepare mixed rubber of natural rubber/acrylonitrile graft copolymer and deproteinized natural latex; or adding the valeronitrile latex into the butyronitrile latex, wherein the adding amount of the valeronitrile latex is 20-500% of the dry rubber mass of the butyronitrile rubber in the butyronitrile latex, uniformly mixing to prepare the mixed rubber of the natural rubber/acrylonitrile graft copolymer and the butyronitrile latex, or adding the valeronitrile latex into the natural latex, wherein the adding amount of the valeronitrile latex is 20-500% of the dry rubber mass of the natural rubber in the natural latex, uniformly mixing to prepare the mixed rubber of the natural rubber/acrylonitrile graft copolymer and the natural latex.
In the invention, the grafting ratio is calculated by adopting the weight change before and after the graft copolymerization of the deproteinized natural latex according to the following formula:
G＝[(Wg-W0)/W0]×％
in the above formula, G is the graft ratio, W0For the dry mass of deproteinized natural latex, WgIs the dry gum mass of the grafted product.
The invention is characterized in that:
1. firstly, natural latex is deproteinized and purified, interference of protein, phospholipid and the like on polymerization reaction is eliminated, acrylonitrile monomers are smoothly grafted to rubber chains of the natural latex, the phenomena of low grafting efficiency, high monomer residue, unstable polymerized emulsion, easy emulsion breaking and flocculation and the like which are easily caused by common natural latex graft polymerization are avoided, and the reaction is easy to control;
2. compared with butyronitrile latex, the rubber chain in a high-purity environment is adopted to replace a butadiene component, so that the high molecular weight of the graft copolymer can be maintained, the use of butadiene gas with high risk in the preparation process is avoided, the reaction is carried out under the mild condition of normal pressure, and the reaction is safe and controllable. The physical strength of the obtained copolymer is superior to that of nitrile rubber;
3. in the graft polymerization reaction, the diffusant can dissolve the reaction monomer and the rubber phase at the same time, which is beneficial to the diffusion of the monomer to the rubber phase, and meanwhile, the introduction of the second monomer is not only beneficial to the grafting rate of acrylonitrile, but also participates in graft copolymerization, and the further introduction of the coupling agent can improve the combination between the acrylonitrile and the natural rubber molecular chain, thereby leading to the improvement of the physical properties of the polymerization product or the appearance of new properties;
4. the reaction temperature is controlled in a range of 10-85 ℃ in sections, and the reaction monomers and the coupling agent are promoted to diffuse to the rubber phase at the temperature of more than 40 ℃ so as to be fully distributed in the rubber phase. The temperature is below 30 ℃, so as to avoid the monomer self-polymerization to form a homopolymer and improve the grafting rate of the acrylonitrile.
5. And non-gum substances such as protein and phospholipid serving as a surface protective layer of the rubber particles are removed, and an emulsifier with more stable performance is replaced, so that a microenvironment more suitable for polymerization reaction is provided, and the grafting rate of acrylonitrile and the stability of latex are ensured.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a preparation method of an acrylonitrile/natural rubber graft copolymer, and the obtained valeronitrile latex has the advantages of both natural latex and nitrile latex, namely high elasticity, elongation and low creep which are superior to nitrile rubber; the oil resistance, the aging resistance, the acid and alkali resistance, the heat resistance, the weather resistance, the puncture resistance and the air tightness are superior to those of natural rubber. Meanwhile, the obtained valeronitrile latex can be mixed with butyronitrile latex or natural latex in any proportion, namely, the acrylonitrile modified natural rubber is provided, and the problem of compatibility of the natural rubber and the butyronitrile rubber is solved.
Detailed Description
In order to make the invention more comprehensible, preferred embodiments are described in detail below.
In the present invention, all percentages are by mass unless otherwise specified.
Example 1
Using high ammonia natural latex (60 wt%) as a raw material, deproteinization purification treatment was carried out by a known method to obtain 100kg (60 wt%) of deproteinized natural latex having a water-pumping protein content of 30. mu.g/g (ASTM D5712). Dissolving emulsifier 0.25kg Sodium Dodecyl Sulfate (SDS) and 1.0kg polyoxyethylene lauryl ether (brij-35) in 140kg deionized water, stirring to obtain emulsifier solution, adding 100kg of the emulsifier solution into the deproteinized natural latex to obtain 30 wt% solidStirring and dripping 1.15L of acrylic acid into deproteinized natural latex emulsion with the content under the protection of nitrogen, adjusting the pH value to be about 3.7, controlling the temperature to be 50 +/-2 ℃, keeping stirring for 1h, dripping 12.5kg of acrylonitrile monomer and 10kg of cyclohexane, keeping stirring for 3h, cooling to be 20 +/-2 ℃, slowly dripping 2.5L of 2.8 percent potassium persulfate (KPS) aqueous solution for 0.5h, and slowly dripping 2.5L of 1.0 percent NaHSO into the deproteinized natural latex emulsion3The aqueous solution is used for 0.5h, stirring is maintained for 1h, 40kg of the emulsifier solution is added, 2.5L of 2.8% KPS aqueous solution is slowly dropped, and 2.5L of 1.0% NaHSO aqueous solution is slowly dropped for 0.5h3And (3) maintaining the reaction for 8h when the aqueous solution is used for 0.5h, stopping the reaction, slowly dropwise adding 1% KOH solution, adjusting the pH value of the obtained valeronitrile latex to 9-10, and adjusting the total solid mass fraction to 30% by using deionized water.
Example 2
Taking the same dosage of deproteinized natural latex as the first embodiment, dissolving 7.5kg of emulsifier potato starch in 140kg of deionized water, raising the temperature to 78 +/-2 ℃ under the protection of nitrogen, stirring until the mixture is clear and slightly blue, adding the deproteinized natural latex to prepare latex slurry after 1 hour, dropwise adding 4.0kg of methyl acrylate monomer, 20kg of acrylonitrile monomer and 0.2kg of tetraethyleneglycol dimethacrylate, stirring and cooling to 65 +/-2 ℃, keeping the temperature for 2 hours, naturally cooling to 15 +/-2 ℃, dropwise adding 5.0L of 2.8% potassium persulfate aqueous solution after 0.5 hour, and dropwise adding 5.0L of 1.0% NaHSO3The aqueous solution was kept stirring for 3h at 0.5h, and 1.0L of 2.8% KPS aqueous solution was slowly added dropwise, and 1.0L of 1.0% NaHSO was slowly added dropwise at 0.5h3And (3) maintaining the reaction for 8h when the aqueous solution is used for 0.5h, stopping the reaction, slowly dropwise adding 1% KOH solution, adjusting the pH value of the obtained valeronitrile latex to 9-10, and adjusting the total solid mass fraction to 30% by using deionized water.
Example 3
Taking deproteinized natural latex, deionized water and an emulsifier, controlling the use amount to be the same as that of the first embodiment, controlling the temperature to be 45 +/-2 ℃ under the protection of nitrogen, dropwise adding 5.0kg of solvent gasoline, 6.1kg of acrylonitrile monomer and 4.0kg of 1% N, N-methylene bisacrylamide, keeping stirring for 4 hours, naturally cooling to be 25 +/-2 ℃, slowly dropwise adding 5.0L of 2.5% tert-butyl hydrogen peroxide aqueous solution for 0.5 hour, slowly dropwise adding 5.0L of 4.0% tetraethylenepentamine aqueous solution for 0.5 hour, keeping reacting for 2 hours, cooling to be 15 +/-2 ℃, keeping for 6 hours, stopping the reaction, reducing the temperature to be room temperature, slowly dropwise adding 1% ammonia aqueous solution, adjusting the pH value of the obtained valeronitrile latex to be 9-10, and adjusting the total solid mass fraction to be 30% by using the deionized water.
Example 4
Taking the same dosage of deproteinized natural latex as the first embodiment, respectively taking 0.72kg of emulsifier beta-cyclodextrin and 0.78 kg of tween-800.72 kg of emulsifier beta-cyclodextrin, dissolving the emulsifiers beta-cyclodextrin and tween-800.72 kg of emulsifier beta-cyclodextrin in 140kg of deionized water, adding the emulsifiers beta-cyclodextrin and tween-800.72 kg of emulsifier beta-cyclodextrin into the deproteinized natural latex, introducing nitrogen for protection, uniformly stirring, adding 1.5kg of N-vinyl pyrrolidone monomer, 20kg of acrylonitrile monomer and 2kg of hydroxyethyl acrylate monomer, heating to 70 +/-2 ℃, keeping stirring for 4 hours, naturally cooling to 20 +/-2 ℃, dissolving 0.19kg of cumene hydroperoxide into 4.0kg of methyl methacrylate monomer, dropwise adding the mixture into the reaction emulsion, keeping stirring for 10 hours, stopping the reaction, slowly dropwise adding 1% of KOH solution, adjusting the pH value of the obtained valeronitrile latex to 9-10, and adjusting the total solid mass fraction to 30% by using deionized water.
Example 5
Taking the same dosage of deproteinized natural latex as the first embodiment, respectively taking 2.0kg of caprolactam to dissolve in 140kg of deionized water, adding the caprolactam into the deproteinized natural latex, introducing nitrogen to protect and uniformly stirring, adding 5kg of cyclohexane, 25kg of acrylonitrile monomer, 5kg of hydroxyethyl acrylate monomer and 6.0kg of 1% N, N-methylene bisacrylamide, heating to 50 +/-2 ℃, keeping stirring for 4 hours, naturally cooling to 20 +/-2 ℃, slowly dropwise adding 2.5L of 2.8% potassium persulfate aqueous solution, and slowly dropwise adding 2.5L of 1.0% NaHSO for 0.5 hour3The aqueous solution was kept stirring for 0.5h, and then 3.0L of 2.8% KPS aqueous solution was slowly added dropwise, and 3.0L of 1.0% NaHSO was slowly added dropwise for 0.5h3And (3) maintaining the reaction for 10h when the aqueous solution is used for 0.5h, stopping the reaction, slowly dropwise adding 1% KOH solution, adjusting the pH value of the obtained valeronitrile latex to 9-10, and adjusting the total solid mass fraction to 30% by using deionized water.
Example 6
The amount of deproteinized natural latex was the same as in example one, 1.5kg of carboxylated chitosan as emulsifier was dissolved in 140kg of deionized water, adding the mixture into deproteinized natural latex, introducing nitrogen, stirring uniformly, adding 5kg of solvent gasoline, 25kg of acrylonitrile monomer, 5kg of hydroxyethyl acrylate monomer and 1kg of tetraethyleneglycol dimethacrylate, heating to 50 +/-2 ℃, keeping stirring for 4 hours, naturally cooling to 20 +/-2 ℃, slowly adding 6.0L of 2.5% tert-butyl hydrogen peroxide aqueous solution for 0.5 hour when in use, slowly adding 5.0L of 4.0% tetraethylenepentamine aqueous solution for 0.5 hour when in use, keeping reacting for 2 hours, cooling to 15 +/-2 ℃, keeping for 8 hours, stopping the reaction, cooling to room temperature, slowly adding 1% ammonia aqueous solution, adjusting the pH value of the obtained valeronitrile latex to 9-10, and adjusting the total solid mass fraction to 30% by using deionized water.
Example 7
1.0kg of polyoxyethylene lauryl ether (brij-35) was dissolved in an appropriate amount of deionized water, and 100kg (30 wt%) of the valeronitrile latex obtained in example one and 100kg (30 wt%) of the concentrated natural rubber latex were added in this order under mechanical stirring. And further stirring uniformly by adopting a mechanical homogenizing device, and adjusting the mass fraction of the total solid to 40 wt% by using deionized water.
Example 8
1.5kg of polyoxyethylene octylphenol ether-10 was dissolved in an appropriate amount of deionized water, and 100kg (30 wt%) of the valeronitrile latex obtained in example three and 100kg (45 wt%) of a commercially available butyronitrile latex J1830 were added in this order under mechanical stirring. And further stirring uniformly by adopting a mechanical homogenizing device, and adjusting the mass fraction of the total solid to 30 wt% by using deionized water.
To the latices obtained in the above examples 1 to 8 were added 1.0 part of sulfur, 2 parts of zinc oxide, 0.25 part of BZ, 0.5 part of ZDEC, respectively, and vulcanized in a water bath at 50 ℃ for 2.0 hours, and 0.5 part of 2, 6-di-tert-butyl-4-methylphenol, respectively, to obtain vulcanized latices, and latex gloves were prepared by dipping, and the following tests were carried out:
the gloves thus produced were subjected to conventional tests for their physical and mechanical properties in accordance with EN 3881994. At the same time, wear, shear, puncture and tear tests were also performed. Each test result is classified into 5 grades, i.e., 0-5 grades, and the larger the number, the higher the grade. The gloves were tested for solvent resistance according to EN 374-31994. The results of the tests for each solvent were ranked 6, the higher the number, the higher the rank. The test results are shown in table 1.
TABLE 1
Claims (12)
1. The valeronitrile latex is characterized in that the valeronitrile latex is acrylonitrile/natural rubber graft copolymer emulsion which is prepared by graft copolymerization of deproteinized natural latex, a diluent, an emulsifier, a diffusant, a pH value buffering agent, an acrylonitrile monomer, a second comonomer, a coupling agent and an oxidation-reduction initiator.
2. A valeronitrile latex according to claim 1, wherein the deproteinised natural latex is prepared by deproteinising natural latex from one or more of in-situ latex obtained from latex of natural rubber tree or concentrated latex stored in ammonia; the mass content of the rubber dry glue in the deproteinized natural latex is 5-60%, and the protein content of the deproteinized natural latex is lower than 110 mu g/g.
3. A valeronitrile latex according to claim 1, wherein the diluent is pure water or ammonia water with mass concentration of 1-5%, and the addition amount is 20-500% of the mass of rubber dry rubber in the deproteinized natural latex.
4. A valeronitrile latex and a preparation method thereof according to claim 1, wherein the addition amount of the acrylonitrile monomer is 1-80% of the mass of the rubber dry glue in the deproteinized natural latex.
5. A valeronitrile latex according to claim 1, wherein the second comonomer is at least one of acrylic acid, methacrylic acid, acrylamide, methacrylamide, styrene, N-vinylpyrrolidone, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and glycidyl methacrylate, and is added in an amount of not more than 80% by weight of the rubber dry mass in the deproteinised natural latex.
6. The valeronitrile latex according to claim 1, wherein the emulsifier is casein, chitosan oligosaccharide, water-soluble chitosan, carboxylated chitosan, mucopolysaccharide, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate, carbomer resin, potato starch, corn starch, glutinous rice starch, carbomer, flaxseed gum, konjac gum, caprolactam, polyglutamic acid, cyclodextrin, betaine, carbomer, tween, span, lanolin, agar, oleic acid, ammonium oleate, triethanolamine, polyethyleneimine, alkyldimethylamine oxide, cetyltrimethylammonium bromide, polyhydroxybutyrate, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polyoxyethylene lauryl ether, polyoxyethylene octylphenol ether-10, polyglycerol glycidyl ether, monthly silicate, At least one of polyoxyalkylene ester surfactant, polyol fatty acid ester surfactant, polyoxyalkylene ether surfactant, dodecyltrimethylammonium bromide, alkylbenzenesulfonate, alkylsulfonate, naphthalenesulfonate, diisooctylsulfosuccinate, diphenylethersulfonate, benzenesulfonate, naphthalenesulfonate, alkylsulfonate, dialkylsulfosuccinate, alkylsulfate, polyoxyalkylene diphenylphenol sulfate, polyoxyalkylene sulfate, trisstyrenated phenol sulfate, polyoxyalkylene phenyl ether sulfate, polyoxyalkylene alkyl sulfate salt, polyoxyalkylene alkyl phenyl ether sulfate salt, polyoxyalkylene triphenylethylenated phenol sulfate salt, polyoxyalkylene diphenylethylenated phenol sulfate salt, alkylamine derivative, and quaternary ammonium salt polymer, the adding amount is 0.1-10% of the mass of the rubber dry glue in the deproteinized natural latex.
7. A valeronitrile latex according to claim 1, wherein the dispersing agent is at least one of cyclohexane, solvent gasoline, heptane, benzene, xylene and petroleum ether, and is added in an amount of no more than 20% by mass of rubber dried rubber in the deproteinized natural latex.
8. A valeronitrile latex according to claim 1 wherein the coupling agent is at least one of N, N-methylenebisacrylamide, tetraethylene glycol dimethacrylate, divinylbenzene, triallyl isocyanurate and diallyl phthalate, present in an amount of no more than 10% by weight of the dry rubber mass of the deproteinised natural rubber latex.
9. A valeronitrile latex according to claim 1, wherein the oxidant in the redox initiator is at least one of hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, persulfate, dibenzoyl peroxide and potassium permanganate, and the addition amount is 0.01-10% of the mass of rubber dry rubber in the deproteinized natural latex; the reducing agent in the redox initiator is at least one of sodium bisulfite, sodium thiosulfate, tetraethylenepentamine, ethylenediamine, glucose, N-dimethylaniline, thiourea and ascorbic acid, and the adding amount of the reducing agent is 0.01-10% of the mass of the rubber dry glue in the deproteinized natural latex.
10. A valeronitrile latex according to claim 1, wherein the pH buffer is at least one of lactic acid, acetic acid, succinic acid, citric acid, monopotassium phosphate, dipotassium phosphate, monosodium phosphate, disodium phosphate, sodium phosphate, potassium acetate, sodium hydroxide, ammonia, potassium hydroxide, sodium carbonate and sodium bicarbonate, and is added in an amount of 0.0001-10% by weight of rubber dry rubber in the deproteinized natural latex.
11. A process for preparing valeronitrile latex according to any one of claims 1 to 10, wherein deproteinised natural latex is obtained by subjecting natural latex to a purification treatment to obtain deproteinised natural latex, which is diluted with a diluent and stirred until homogeneous, and then an emulsifier is added to prepare a natural latex mixture; adding a pH value buffering agent to set the pH value of the natural latex mixed solution within a range of 3.5-5.5 or 8-11; adding a second comonomer, an acrylonitrile monomer and a redox initiator to obtain a polymerization reaction system, wherein the solid content is controlled to be 15-50 wt%, the nitrogen protection penetrates through the whole reaction process, the reaction temperature is controlled to be 10-85 ℃, and the reaction time is controlled to be 0.5-30hr, so that the natural rubber/acrylonitrile graft copolymer emulsion with the acrylonitrile grafting rate of 1-70%, namely valeronitrile latex is prepared.
12. Use of a valeronitrile latex according to any one of claims 1 to 10, wherein the valeronitrile latex is added to deproteinized natural latex in an amount of 20 to 500% by weight of rubber dry mass in the deproteinized natural latex, and is mixed uniformly to prepare a mixed rubber of natural rubber/acrylonitrile graft copolymer and deproteinized natural latex; or adding the valeronitrile latex into the butyronitrile latex, wherein the adding amount of the valeronitrile latex is 20-500% of the dry rubber mass of the butyronitrile rubber in the butyronitrile latex, uniformly mixing to prepare the mixed rubber of the natural rubber/acrylonitrile graft copolymer and the butyronitrile latex, or adding the valeronitrile latex into the natural latex, wherein the adding amount of the valeronitrile latex is 20-500% of the dry rubber mass of the natural rubber in the natural latex, uniformly mixing to prepare the mixed rubber of the natural rubber/acrylonitrile graft copolymer and the natural latex.
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| CN117511010A (en) * | 2023-10-27 | 2024-02-06 | 云南森洁医用乳胶器材有限公司 | Medical surgical glove based on deproteinized natural concentrated latex and preparation method thereof |
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