Preparation method of formamide-free environment-friendly rubber and plastic foamed product
阅读说明：本技术 一种不含甲酰胺的环保型橡塑发泡制品的制备方法 (Preparation method of formamide-free environment-friendly rubber and plastic foamed product ) 是由 高铁强 高铁彦 高景岐 于 2019-10-18 设计创作，主要内容包括：本发明提供一种不含甲酰胺的环保型橡塑发泡制品的制备方法,属于发泡材料技术领域,包括以下步骤：混炼,将丁腈橡胶、聚氯乙烯和发泡剂组合物混合后加入,经高温混炼后,加工成胶片；复炼：将胶片加入硫化剂,进行二次复炼,加工成胶条；发泡,将胶条挤出成型后,进行硫化发泡,即得橡塑发泡制品。其中,发泡剂组合物包括核壳结构,其具有：含有碳酸氢盐和硝基弧的发泡剂核；包围核的壳,其中,壳的软化点高于核分解成为气体的温度。本发明制备方法制得的橡塑发泡制品,发泡效果好,能够获到均匀细密、闭孔且独立的泡孔结构,使得橡塑发泡制品的吸水率、导热系数较低,隔声指数较高,具有较好的保温、防水及隔声效果。(The invention provides a preparation method of an environment-friendly rubber and plastic foaming product without formamide, belonging to the technical field of foaming materials and comprising the following steps: mixing, namely mixing the nitrile rubber, the polyvinyl chloride and the foaming agent composition, adding the mixture, mixing at a high temperature, and processing into a rubber sheet; re-smelting: adding a vulcanizing agent into the rubber sheet, carrying out secondary remill, and processing into rubber strips; foaming, namely extruding and molding the rubber strip, and then vulcanizing and foaming to obtain the rubber and plastic foamed product. Wherein the blowing agent composition comprises a core-shell structure having: a blowing agent core comprising bicarbonate and nitro arcs; a shell surrounding the core, wherein the softening point of the shell is higher than the temperature at which the core decomposes into a gas. The rubber-plastic foamed product prepared by the preparation method disclosed by the invention is good in foaming effect, and can obtain a uniform, fine, closed and independent foam cell structure, so that the rubber-plastic foamed product is low in water absorption rate and heat conductivity coefficient, high in sound insulation index and good in heat preservation, water resistance and sound insulation effects.)
1. A blowing agent composition comprising a core-shell structure having:
a blowing agent core comprising bicarbonate and nitro arcs;
a shell surrounding the core, wherein the shell has a softening point above a temperature at which the core decomposes into a gas.
2. A blowing agent composition according to claim 1, wherein: the core also contains caffeic acid amide derivatives shown in formula (I) and cinnamic acid derivatives shown in formula (II),
in formula (I), -R is selected from one of the following: -CH3、-CH-(CH3)2、-CH2-CH(CH3)2、-CH(CH3)-CH2-CH3、-CH2-C6H5。
3. A blowing agent composition according to claim 1, wherein: the gas evolution of the blowing agent composition was 400-435 mL/g.
4. Use of the blowing agent composition of claim 1 or 2 or 3 for the preparation of formamide-free foamed articles.
5. A thermally foamable formamide-free rubber-plastic composition comprising the blowing agent composition of claim 1 or 2 or 3, nitrile rubber and polyvinyl chloride.
6. A method for preparing a formamide-free environment-friendly rubber-plastic foamed product by using the rubber-plastic composition of claim 5, which comprises the following steps:
mixing, namely mixing the nitrile rubber, the polyvinyl chloride and the foaming agent composition, adding the mixture, mixing at a high temperature, and processing into a rubber sheet;
-remill: adding a vulcanizing agent into the rubber sheet, carrying out secondary remill, and processing into rubber strips;
foaming, namely extruding and molding the rubber strip, and then vulcanizing and foaming to obtain the rubber and plastic foamed product.
7. The method for preparing the formamide-free environment-friendly rubber-plastic foamed product according to claim 6, wherein the method comprises the following steps: the vulcanization foaming temperature of the vulcanization foaming is 150-220 ℃, the time is 15-40min, preferably, the temperature is 170-200 ℃, and the time is 20-30 min.
8. The environmentally friendly rubber-plastic foamed product obtained by the preparation method according to claim 6 or 7.
9. The environment-friendly rubber-plastic foamed product according to claim 8, wherein: the density of the environment-friendly rubber and plastic foaming product is 0.25-0.42g/cm3。
10. The environment-friendly rubber-plastic foamed product according to claim 8, wherein: the heat conductivity coefficient of the environment-friendly rubber and plastic foaming product is less than or equal to 0.028W/(m.k).
Technical Field
The invention belongs to the technical field of foaming materials, and particularly relates to a preparation method of an environment-friendly rubber and plastic foaming product without formamide.
Background
The foam material has the advantages of low density, light weight, large specific surface area, high specific mechanical property, good damping property and the like, is widely applied to the fields of aviation, aerospace, atomic energy, medicine, environmental protection, metallurgy, mechanical construction, electrochemistry, petrochemical industry and the like, and is gradually developed into an excellent engineering material. The preparation of various foaming materials can not only be independent of the use of foaming agents, but also the properties of the foaming agents have very important influence on the performances of the foaming materials and the processing and forming processes thereof, so that the research on the foaming agents has become a research hotspot in the field of foaming materials and has made great progress. The foaming agent can make polymer materials such as plastics or rubber form cells, and the influence of the foaming agent on the performance of the foaming material is very important. Blowing agents can be classified into physical blowing agents, which do not chemically react when generating gas, and chemical blowing agents, which generate gas by gasification or volatilization, according to the source of the generated gas, and mainly include Hydrofluorocarbons (HFCs), chlorofluorocarbons (CFCs), water, and supercritical (CO)2) And alkanes and the like. The chemical foaming agents are very various and can be divided into organic foaming agents and inorganic foaming agents, and common inorganic foaming agents comprise bicarbonate, inorganic carbonate and the like; the organic foaming agent includes Azodicarbonamide (AC), sulfonyl hydrazides and the like.
The conventional foaming materials mostly use a single plastic or resin as a foaming matrix. If the rubber is used as the framework material, the foaming material has good elasticity, but the creep motion of rubber molecules can cause the foaming material to have poor stiffness and larger shrinkage rate, and the foaming material can be seriously deformed after being parked or used for a long time. The product which only uses plastic as a foaming matrix has poor elasticity, and the compression permanent shape is enlarged, thereby bringing a lot of invariance to the subsequent processing of the material. The rubber-plastic foamed product is a composite material which takes rubber and plastic as main parts and gas as a filler. The Nitrile Butadiene Rubber (NBR) has the dissolution parameter of 9.4-9.5 and the cohesive energy density of 370.1-377.6J/
Disclosure of Invention
An object of the present invention is to provide a foaming agent composition which is capable of stably releasing gas when a foaming master batch reaches a melting temperature, has a large gas generation amount, stabilizes the structure and uniformity of cells, prevents agglomeration of nuclear materials and moisture absorption, and avoids generation of bubbles having a large pore diameter and communication between continuous bubbles.
The technical scheme adopted by the invention for realizing the purpose is as follows:
a blowing agent composition comprising a core-shell structure having:
a blowing agent core comprising bicarbonate and nitro arcs;
a shell surrounding the core, wherein the softening point of the shell is higher than the temperature at which the core decomposes into a gas.
The decomposition temperature of the bicarbonate and the nitro-arc is lower than the melting temperature of the foaming master batch, when the foaming master batch does not reach the melting state, the foaming master batch is decomposed to generate a large amount of gas, and the foaming master batch can not wrap the gas, so that the gas loss is caused. The shell structure in the foaming agent composition can form a protective layer on the surface of a foaming substance, so that the foaming substance can be prevented from being decomposed into gas when a foaming master batch reaches a melting temperature, and the shell substance is softened when the foaming master batch reaches the melting temperature, and then the released core substance is instantaneously decomposed into gas, so that the gas generation amount is larger, the cell rate of the foaming material is improved, the density of the foaming material is reduced, and the hardness, the tensile strength, the fracture elongation and the sound insulation performance of the foaming material can be improved; the shell structure in the foaming agent composition can also obviously prevent the agglomeration and moisture absorption of nuclear substances, improve the mixing property with a foaming parent material, avoid the generation of bubbles with larger pore diameters and the communication between continuous bubbles, form a uniform, fine, closed and independent cell structure, reduce the water absorption rate and the heat conductivity coefficient of the foaming material, and improve the sound insulation index of the foaming material, thereby improving the heat preservation, waterproof and sound insulation effects of the foaming material.
According to one embodiment of the invention, the core also contains caffeic acid amide derivatives shown in formula (I) and cinnamic acid derivatives shown in formula (II),
wherein, -R is selected from one of the following: -CH3、-CH-(CH3)2、-CH2-CH(CH3)2、-CH(CH3)-CH2-CH3、-CH2-C6H5. Caffeic acid amide derivative shown as formula (I) and cinnamon shown as formula (II)The addition of the acid derivative can adjust the decomposition temperature and speed of the foaming shell substance, stably release gas, avoid communication among continuous bubbles and stabilize the structure and uniformity of foam cells of the foaming material, thereby further reducing the water absorption and heat conductivity of the foaming material and finally improving the heat preservation and waterproof effects of the foaming material; meanwhile, the addition of the caffeic acid amide derivative and the cinnamic acid derivative can also improve the skin thickness of the foamed rubber product and improve the hardness and strength of the foamed rubber product; in addition, the addition of the caffeic acid amide derivatives and cinnamic acid derivatives has no inhibitory effect on the vulcanization process. More preferably, the caffeic acid amide derivatives are used in an amount of 3.5 to 6.0 wt% and cinnamic acid derivatives are used in an amount of 12 to 25 wt% based on the amount of foaming agent.
According to an embodiment of the present invention, the blowing agent composition has a gas evolution of 400-435 mL/g.
It is a further object of the present invention to provide the use of the above blowing agent composition for the preparation of formamide-free foamed articles. The foaming agent composition does not generate formamide in the decomposition process, and the obtained foaming product is environment-friendly.
The invention also aims to provide a thermal foaming formamide-free rubber and plastic composition which contains the foaming agent composition, nitrile rubber and polyvinyl chloride.
The invention also aims to provide a preparation method of the formamide-free environment-friendly rubber and plastic foaming product with good foaming effect and capable of obtaining a uniform, fine, closed and independent cell structure, which comprises the following steps:
mixing, namely mixing the nitrile rubber, the polyvinyl chloride and the foaming agent composition, adding the mixture, mixing at a high temperature, and processing into a rubber sheet;
-remill: adding a vulcanizing agent into the rubber sheet, carrying out secondary remill, and processing into rubber strips;
foaming, namely extruding and molding the rubber strip, and then vulcanizing and foaming to obtain the rubber and plastic foamed product.
According to one embodiment of the present invention, the vulcanization foaming temperature of the vulcanization foaming is 150-.
The invention also aims to provide the environment-friendly rubber and plastic foam product which is obtained by the preparation method and has low water absorption, low heat conductivity and high sound insulation index, and has good heat preservation, waterproof and sound insulation effects.
The environment-friendly rubber and plastic foaming product has closed-cell structure, independent pores and low heat conductivity coefficient, water vapor permeability and water absorption rate, so that the environment-friendly rubber and plastic foaming product has low density and good heat-insulating and waterproof performance, can prevent water vapor from permeating into the material even if the surface layer of the material is damaged, and has good sound insulation, flexibility and ageing resistance; the environment-friendly rubber-plastic foamed product has excellent fireproof performance which is higher than the standard of GB/8624B 1-grade flame-retardant materials; the environment-friendly rubber and plastic foaming product has a wide use temperature range from-40 ℃ to 105 ℃. Based on the characteristics, the environment-friendly rubber and plastic foaming product can be widely applied to heat preservation and insulation of various water vapor pipelines in the industries of central air-conditioning refrigeration rooms, buildings, ships, vehicles and the like, and can be used for manufacturing handles, expansion sleeves and the like of fitness equipment, medical instruments and daily necessities.
According to one embodiment of the invention, the density of the environment-friendly rubber-plastic foamed product is 0.25-0.42g/cm3。
According to one embodiment of the invention, the thermal conductivity coefficient of the environment-friendly rubber-plastic foamed product is less than or equal to 0.028W/(m.k). The environment-friendly rubber and plastic foaming product not only has excellent moisture resistance, but also has lower heat conductivity coefficient, namely under the same environmental condition, the use thickness of the environment-friendly rubber and plastic foaming product is more than half thinner than that of other heat-insulating materials, and the available space of a building is improved.
Compared with the prior art, the invention has the beneficial effects that: the foaming agent composition can prevent a foaming substance from being decomposed into gas when a foaming master batch reaches a melting temperature, and stably releases the gas when the foaming master batch reaches the melting temperature, so that the foaming amount is large, and the structure and uniformity of foam cells of a foaming material are stabilized; the foaming agent composition can remarkably prevent the agglomeration and moisture absorption of nuclear substances, improves the mixing property with a foaming parent material, and can avoid the generation of bubbles with larger pore diameters and the communication between continuous bubbles; the rubber and plastic foamed product prepared by the foaming agent composition has good foaming effect, can obtain a uniform, fine, closed and independent foam cell structure, and has low water absorption rate and heat conductivity coefficient, high sound insulation index and good heat preservation, waterproof and sound insulation effects.
The invention adopts the technical scheme to provide the preparation method of the formamide-free environment-friendly rubber and plastic foaming product, overcomes the defects of the prior art, and has reasonable design and convenient operation.
Drawings
FIG. 1 is a decomposition measuring apparatus of a blowing agent composition in test example 1 of the present invention;
FIG. 2 is a graph of gas evolution per unit mass of a blowing agent composition in test example 1 of the present invention as a function of time;
FIG. 3 is the gas evolution of the blowing agent composition of test example 1 of the present invention;
FIG. 4 shows the density of the rubber-plastic foamed product in test example 2 of the present invention;
FIG. 5 shows the hardness of the rubber-plastic foamed product in test example 2 of the present invention;
FIG. 6 shows tensile strength test and elongation at break of the rubber-plastic foamed product in test example 2 of the present invention;
FIG. 7 is a photograph of a rubber-plastic foamed product in test example 2 of the present invention;
FIG. 8 is a distribution diagram of the pore diameters of the rubber-plastic foamed product in test example 2 of the present invention;
FIG. 9 shows the water absorption of the rubber-plastic foamed product in test example 3 of the present invention;
FIG. 10 shows the thermal conductivity of the rubber-plastic foamed product in test example 3 of the present invention;
FIG. 11 is a sound insulation index of a rubber-plastic foamed product in test example 3 of the present invention.
Description of reference numerals: 1. carrying out oil bath; 2. a thermometer; 3. a gas measuring pipe; 4. water; 5. a level bottle.
Detailed Description
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It is not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
These examples are provided only for more specifically illustrating the present invention, and it is apparent to those skilled in the art that the scope of the present invention is not limited to these examples according to the gist of the present invention.
One embodiment of the present invention provides a blowing agent composition comprising a core-shell structure having:
a blowing agent core comprising bicarbonate and nitro arcs;
a shell surrounding the core, wherein the softening point of the shell is higher than the temperature at which the core decomposes into a gas.
The decomposition temperature of the bicarbonate and the nitro-arc is lower than the melting temperature of the foaming master batch, when the foaming master batch does not reach the melting state, the foaming master batch is decomposed to generate a large amount of gas, and the foaming master batch can not wrap the gas, so that the gas loss is caused. The shell structure in the foaming agent composition can form a protective layer on the surface of the foaming substance, so that the foaming substance can be prevented from being decomposed into gas when the foaming master batch reaches the melting temperature, and the shell substance is softened when the foaming master batch reaches the melting temperature, and then the released core substance is instantaneously decomposed into gas, so that the gas generation amount is larger, the cell rate of the foaming material is improved, the density of the foaming material is reduced, and the hardness, the tensile strength, the breaking elongation and the sound insulation performance of the foaming material can be improved; the shell structure in the foaming agent composition can also obviously prevent the agglomeration and moisture absorption of core substances, improve the mixing property with a foaming parent material, avoid the generation of bubbles with larger pore diameters and the communication between continuous bubbles, form a uniform, fine, closed and independent cell structure, reduce the water absorption rate and the heat conductivity coefficient of the foaming material and further improve the heat preservation and waterproof effects of the foaming material, wherein the closed cell rate is more than 96 percent, and the pore diameter of the cells is 30-50 mu m.
In one embodiment of the invention, the bicarbonate is selected from potassium bicarbonate and/or sodium bicarbonate, having a particle size200-300 meshes. The bicarbonate has the characteristics of good nucleation effect, endothermic decomposition, safety and the like, and the generated gas is CO2No pollution and environmental protection. And when the particle diameter of the alkali metal bicarbonate particles is 200-300 meshes, the uniformity of the foam material cells can be improved. The nitro-arc is selected from N-nitro-arc and/or 1, 2-dinitro-arc. More preferably, the core material is potassium bicarbonate and 1, 2-dinitro arc in a weight ratio of 1:0.5 to 1.5. The preparation method of the 1, 2-dinitro arc comprises the following steps: putting 0.1mol of dinitroguanidine and 300mL of methanol into a 50mL three-neck flask at room temperature, slowly adding 0.05mol of guanidine carbonate after complete dissolution, stirring for reaction for 35min, filtering, washing with ethyl acetate, and drying to obtain the 1, 2-dinitro arc. The decomposition temperature of the potassium bicarbonate in the air is 195-210 ℃ and the decomposition temperature of the 1, 2-dinitro arc in the air is 220-230 ℃, so that the decomposition temperature of the foaming agent composition in the foaming master batch is high, and the quality of a foaming product is improved.
In one embodiment of the present invention, the shell material may be composed of a polymer. The polymer is composed of a polymerizable monomer and a crosslinking agent, and thus the foaming properties, heat resistance and the like of the foaming agent composition can be improved. More preferably, the shell is a polymer comprising acrylonitrile and vinylidene chloride monomers, wherein the acrylonitrile monomers include at least one selected from the group consisting of acrylonitrile, methacrylonitrile, fumaronitrile, α -cyanoethylacrylonitrile, and the higher the ratio of acrylonitrile, the higher the softening point of the shell softening point of the blowing agent composition, the higher the temperature at which the core starts to generate gas, so that the content of acrylonitrile in the polymer is preferably 50 to 75 wt%; the higher the content of vinylidene chloride, the higher the gas barrier property of the formed microspheres, and the lower the content thereof, the lower the gas barrier property of the formed microspheres tends to be, so that the content of vinylidene chloride in the polymer is preferably 20 to 50% by weight. More preferably, other polymerizable monomers may be added in addition to acrylonitrile and/or vinylidene chloride, for example: (meth) acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, dicyclopentenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and isobornyl methacrylate; vinyl chloride, styrene, vinyl acetate, alpha-methylstyrene, chloroprene rubber, butadiene, etc. More preferably, the crosslinking agent is a compound having two or more carbon-carbon double bonds, such as divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, allyl (meth) acrylate, triallyl isocyanate, triacrylformal, trimethylolpropane tri (meth) acrylate, 1, 3-butylglycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and the like, and the content of the crosslinkable monomer is preferably 0.01 to 3 wt% based on the total amount of the polymerizable monomers.
In one embodiment of the present invention, the blowing agent composition obtained under the conditions of using 2 to 5 parts by weight of the shell material per 100 parts by weight of the core material is free from coagulation, premature decomposition and physical change. The thickness of the shell was obtained by measuring the thickness of 5 points in the SEM photograph, and the thickness of the shell was 0.6 to 1 μm. When the shell material is used in an amount of less than 2 parts by weight, the coagulation of the prepared foaming agent composition is serious and early decomposition occurs, and when the shell material is used in an amount of more than 5 parts by weight, the physical properties such as the amount of gas generated by decomposition decreases.
In one embodiment of the present invention, a method of preparing a blowing agent composition comprises the steps of: the above-mentioned blowing agent composition is produced by suspension polymerization of a shell material, a mixture of a polymerizable monomer for the shell material and a crosslinking agent in an aqueous dispersion medium containing a dispersion stabilizer.
In one embodiment of the invention, the core also contains caffeic acid amide derivatives shown in formula (I) and cinnamic acid derivatives shown in formula (II),
wherein, -R is selected from one of the following: -CH3、-CH-(CH3)2、-CH2-CH(CH3)2、-CH(CH3)-CH2-CH3、-CH2-C6H5。
The caffeic acid amide derivatives shown in the formula (I) and the cinnamic acid derivatives shown in the formula (II) can be added to adjust the decomposition temperature and speed of the foaming shell substance, stably release gas, avoid communication between continuous bubbles and stabilize the structure and uniformity of foam cells of the foaming material, thereby further reducing the water absorption rate and the thermal conductivity of the foaming material and finally improving the heat preservation and waterproof effects of the foaming material; meanwhile, the addition of the caffeic acid amide derivative and the cinnamic acid derivative can also improve the skin thickness of the foamed rubber product and improve the hardness and strength of the foamed rubber product; furthermore, the addition of the caffeic acid amide derivative has no inhibitory effect on the vulcanization process. More preferably, the caffeic acid amide derivatives are used in an amount of 3.5 to 6.0 wt% and cinnamic acid derivatives are used in an amount of 12 to 25 wt% based on the amount of foaming agent.
The preparation method of the caffeic acid amide derivative shown as the formula (I) comprises the following steps: dissolving caffeic acid and tetrahydrofuran in self-made N2Sequentially adding NMM and IBCF (N-dimethylformamide) to a penicillin bottle of a protection device at 0 ℃ for reacting for 15min, then adding amino acid, reacting at 0 ℃, tracking the reaction by TLC (thin layer chromatography), detecting by TLC until no substrate exists, reacting the reaction solution at normal temperature for 10h, concentrating the reaction solution under reduced pressure after 10h, extracting the concentrated reaction solution for 2-4 times by ethyl acetate after the concentration under reduced pressure, sequentially washing an organic phase by 3-7% citric acid solution and saturated saline solution, and washing the organic layer by anhydrous Na2SO4Drying, decompressing and concentrating to obtain a product, and purifying the product by column chromatography to obtain a target product. The amino acid is selected from alanine, valine, leucine, isoleucine or phenylalanine.
The preparation method of the cinnamic acid derivative shown in the formula (II) comprises the following steps: firstly, carrying out a phenolization reaction on acetic anhydride and phenolic hydroxyl on a benzene ring, then carrying out a nucleophilic addition reaction on the acetic anhydride, removing water to generate the acetyl cinnamic acid, finally hydrolyzing under an alkaline condition, and acidifying by dilute sulfuric acid to obtain the cinnamic acid derivative shown in the formula (II). Specifically, beta-hydroxybenzoic acid, potassium carbonate and acetic anhydride with the molar ratio of 1:4:1 are radiated and stirred in a microwave reactor with the power of 500-800W for reaction for 1-3h, and the solvent and the byproducts are removed to obtain the cinnamic acid derivative shown in (II).
In one embodiment of the present invention, the blowing agent composition has a gas evolution of 400-.
An embodiment of the present invention provides the use of the above blowing agent composition for the preparation of a foamed article free of formamide. The foaming agent composition of the embodiment does not generate formamide in the decomposition process, and the obtained foaming product is environment-friendly.
The invention provides a thermal foaming formamide-free rubber and plastic composition, which contains the foaming agent composition, nitrile rubber and polyvinyl chloride.
The embodiment of the invention provides a preparation method of an environment-friendly rubber and plastic foaming product without formamide, which comprises the following steps:
mixing, namely mixing the nitrile rubber, the polyvinyl chloride and the foaming agent composition, adding the mixture, mixing at a high temperature, and processing into a rubber sheet;
-remill: storing the rubber sheet for 12-24h, adding a vulcanizing agent, carrying out secondary remilling, and processing into rubber strips;
foaming, namely extruding and molding the rubber strip, and then vulcanizing and foaming to obtain a rubber and plastic foamed product;
in a preferred embodiment of the method according to this embodiment, 0.2 to 10 wt.%, preferably 0.5 to 5 wt.%, particularly preferably 0.8 to 2.5 wt.%, of the foaming agent composition is added to the rubber-plastic base material, relative to the weight of the rubber-plastic base material.
In one embodiment of the present invention, the mass ratio of the nitrile rubber to the polyvinyl chloride is 4-7:1, for example, 4.2:1, 4.5:1, 5.3:1, 5.8:1, 6:1, 6.7:1, etc.
In order to improve the properties of the foamed article, one or more additives may be further included in the compounding. Suitable additives include, but are not limited to, fillers, flame retardants, anti-aging agents, and crosslinking agents, colorants or pigments, and combinations thereof. In some embodiments, the composition further comprises at least one additive selected from the group consisting of: fillers, processing aids, curing agents, accelerators or combinations thereof. Wherein, relative to the weight of the rubber-plastic parent material, the addition amount of the filler is 20-70 wt%, and the filler can be organic filler and/or inorganic filler. Organic fillers include carbon black, fly ash, graphite, cellulose, starch, flour, wood flour, polymeric fibers such as polyester-based and polyamide-based materials, and the like. Inorganic fillers include calcium carbonate, talc phenolic, fly ash, clay, feldspar, silica or glass powder, fumed silica, alumina, magnesia, antimony oxide, zinc oxide, barium sulfate, calcium sulfate, aluminum silicate, calcium silicate, titanium dioxide, titanates, and the like.
In one embodiment of the present invention, a flame retardant, for example, phosphoric acid esters such as decabromodiphenyl ether, octabromodiphenyl ether, tetrabromodiphenyl ether, tetrabromobisphenol, trimethyl phosphate, triethyl phosphate, trichloroethyl phosphate, and trichloropropyl phosphate, is added during kneading. The fire retardant can be added into the environment-friendly rubber and plastic foaming product in the preparation process, so that the smoke concentration generated by the environment-friendly rubber and plastic foaming product during combustion is lower, the environment-friendly rubber and plastic foaming product is not melted when meeting fire, a fire ball on fire cannot be dropped, and the environment-friendly rubber and plastic foaming product has the characteristic of self-extinguishing. The addition amount of the flame retardant is 2-7 wt% relative to the weight of the rubber-plastic parent material. However, the mechanical property of the foamed product can be reduced by adding the flame retardant, and in order to improve the flame retardant property of the rubber-plastic foamed product and not influence the mechanical property of the rubber-plastic foamed product, the itaconic acid is added at the same time of adding the flame retardant, which probably is because the addition of the itaconic acid can enhance the crosslinking force of the nitrile rubber and the polyvinyl chloride, and prevents the cell wall from thinning, thereby preventing the mechanical property of the foamed product from being reduced. In addition, the addition of itaconic acid can also improve the oxygen index of the foamed product, i.e. enhance the flame retardant properties of the foamed product. Preferably, the addition amount of the itaconic acid is 3-5 wt% of the flame retardant.
In one embodiment of the present invention, an antioxidant such as 2-mercaptobenzimidazole and/or N, N' -di (. beta. -naphthyl) p-phenylenediamine is added during kneading. The anti-aging agent is added in the preparation process of the environment-friendly rubber and plastic foamed product of the embodiment, so that the environment-friendly rubber and plastic foamed product has strong anti-aging performance, and the service life is prolonged. The addition amount of the anti-aging agent is 0.1-0.5 wt% relative to the weight of the rubber-plastic parent material.
In one embodiment of the present invention, a crosslinking agent, such as dicumyl peroxide, is added during the mixing. When the foaming master batch is heated and melted, the viscosity of the foaming master batch is reduced sharply, gas is not easy to wrap the inside of the material, the added dicumyl peroxide is crosslinked with the foaming master batch, the viscosity of the material in a molten state can be properly improved, bubbles generated by a foaming agent are wrapped in the foaming agent, and the uniformity of the pore distribution in the environment-friendly rubber and plastic foaming product of the embodiment is improved.
In one embodiment of the present invention, the mixing step is: pretreating nitrile rubber and polyvinyl chloride at 90-100 deg.C for 3-5min, mixing with foaming agent composition, and mixing at 160-170 deg.C for 10-15 min.
In one embodiment of the invention, the remill temperature is 40-50 ℃ and the time is 3-5 min.
In one embodiment of the present invention, the vulcanizing agent is a sulfur-free vulcanizing agent, and is N, N '-m-phenylene bismaleimide or 4, 4' -dithiodimorpholine.
In one embodiment of the present invention, the vulcanization foaming temperature of the vulcanization foaming is 150-.
An embodiment of the invention provides an environment-friendly rubber and plastic foamed product obtained by the preparation method. The environment-friendly rubber and plastic foam product has closed-cell structure of bubbles, independent pores and low heat conductivity coefficient, water vapor transmittance and water absorption rate, so that the environment-friendly rubber and plastic foam product has low density and good heat-preservation and waterproof performance, can prevent water vapor from permeating into the material even if the surface layer of the material is damaged, and has good sound insulation, flexibility and aging resistance; the environment-friendly rubber-plastic foamed product of the embodiment has excellent fireproof performance which is higher than the standard of GB/8624B 1-grade flame-retardant materials; the environment-friendly rubber and plastic foaming product has a wide use temperature range from-40 ℃ to 105 ℃. Based on the characteristics, the environment-friendly rubber and plastic foamed product can be widely applied to heat preservation and insulation of various water vapor pipelines in the industries of central air-conditioning refrigeration rooms, buildings, ships, vehicles and the like, and can be used for manufacturing handles, expansion sleeves and the like of fitness equipment, medical instruments and daily necessities.
In one embodiment of the present invention, the environmental protection type rubber plastic foaming productThe density is 0.25-0.42g/cm3。
In one embodiment of the invention, the thermal conductivity of the environment-friendly rubber-plastic foamed product is less than or equal to 0.028W/(m.k). The environment-friendly rubber and plastic foaming product not only has excellent moisture resistance, but also has lower heat conductivity coefficient, namely under the same environmental condition, the use thickness of the environment-friendly rubber and plastic foaming product of the embodiment is more than half thinner than that of other heat-insulating materials, and the usable space of a building is improved.
The invention is further illustrated by the following examples. It is to be understood that the examples are for illustrative purposes only and are not intended to limit the scope and spirit of the present invention.
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