CN116020147A - Method for removing organic solvent in polyisoprene coarse latex - Google Patents
Method for removing organic solvent in polyisoprene coarse latex Download PDFInfo
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Abstract
The invention relates to a production method of a polymer, in particular to a method for removing an organic solvent in polyisoprene coarse latex. The method comprises the following steps: carrying out normal pressure distillation on the crude latex without the solvent removed; then, the concentrated latex obtained by atmospheric distillation is subjected to optional reduced pressure distillation; the method further comprises the steps of: during atmospheric distillation, inert gas is sprayed above the liquid level of the crude latex. The method can timely eliminate foam generated in distillation, improve the diffusion rate of the solvent, shorten the solvent removal time, and avoid demulsification as much as possible.
Description
Technical Field
The invention relates to a production method of a polymer, in particular to a method for removing an organic solvent in polyisoprene coarse latex.
Background
The microstructure and performance of the artificial polyisoprene latex are similar to those of natural latex, and besides few surfactants and antioxidants, the artificial polyisoprene latex does not contain other non-rubber components, so that the problems of protein allergy, nitrosamine carcinogenesis and the like of the natural latex can be well solved, and the artificial polyisoprene latex can completely replace the natural latex in the medical fields, such as latex gloves, condoms, medical bandages, medical catheters, foaming cosmetic cottons and the like.
The preparation process of the artificial latex comprises the steps of fully mixing an emulsifying agent with a rubber solution, and emulsifying by mechanical force to obtain a rubber coarse emulsion, wherein the content of a solvent in the coarse emulsion exceeds 30% by volume, and the excessive solvent needs to be distilled off. However, a large amount of foam appears in the distillation process, which increases the difficulty of distilling out the solvent and the distillation time.
CN110860101a reports a method for removing solvent from polyisoprene latex, which comprises the steps of directly contacting atomized raw material polyisoprene latex with steam in a flash evaporator to remove organic solvent with low boiling point; the polyisoprene latex with the organic solvent removed firstly falls onto a baffle type demister and then falls onto the bottom of a flash evaporator to be gathered, and the gathered polyisoprene latex is discharged from the bottom of the flash evaporator; the polyisoprene latex discharged from the bottom of the flash evaporator is cooled and flows back to the inside of the flash evaporator, and is sprayed to the upper part of a baffle type demister in the flash evaporator; and cooling and defoaming the polyisoprene latex falling onto a baffle type demister in the flash evaporator, and then falling to the bottom of the flash evaporator together with the defoamed polyisoprene latex. Although the technology can remove foam, coarse latex is in direct contact with steam, and the high steam temperature can cause demulsification of a large amount of latex particles, so that the technology is not practical.
Therefore, the prior art still has the problems of difficult solvent removal, easy demulsification, long time consumption and more foam, and the production process has lower efficiency.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a method for removing the organic solvent in polyisoprene crude latex, which can timely eliminate foam generated in distillation, improve the diffusion rate of the solvent, shorten the solvent removal time and avoid demulsification as much as possible.
In order to achieve the above object, the present invention provides a method for removing an organic solvent in a crude polyisoprene latex, comprising: performing atmospheric distillation on the polyisoprene coarse latex without the solvent; then, the concentrated latex obtained by atmospheric distillation is subjected to optional reduced pressure distillation;
the method further comprises the steps of: during atmospheric distillation, inert gas is sprayed above the liquid level of the crude latex.
Through the technical scheme, the invention has the following beneficial effects:
the method can timely eliminate foam in the solvent distillation process, improve the solvent transfer rate, shorten the solvent removal time and avoid demulsification as much as possible. In addition, the invention has simple operation, low operation cost, no environmental pollution, continuous operation in the whole process, easy realization of automatic production and stable latex quality.
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FIG. 1 is an apparatus for removing organic solvent in accordance with the practice of the present invention.
Reference numerals
1-a cylindrical tube with fine holes; 2-gas line; 3-a feed inlet of the atmospheric distillation kettle; 4-an inlet for heating medium of the atmospheric distillation kettle; 5-a heating medium outlet of the atmospheric distillation kettle; 6-a solvent outlet of the atmospheric distillation kettle; 7-a discharge port of the normal pressure distillation kettle; 8-a heating medium inlet of the reduced pressure distillation kettle; 9-a heating medium outlet of the reduced pressure distillation kettle; 10-a discharge port of the reduced pressure distillation kettle; 11-a solvent outlet of the reduced pressure distillation kettle; 12-a vacuum control system; 13-an atmospheric distillation kettle; 14-decompressing a distillation kettle; 15-a feed inlet of the reduced pressure distillation kettle.
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 invention provides a method for removing organic solvent in polyisoprene coarse latex, which comprises the following steps: performing atmospheric distillation on the polyisoprene coarse latex without the solvent; then, the concentrated latex obtained by atmospheric distillation is subjected to optional reduced pressure distillation;
The method further comprises the steps of: during atmospheric distillation, inert gas is sprayed above the liquid level of the crude latex.
It is understood that the coarse latex refers to a latex from which the organic solvent has not been removed after emulsification homogenization.
The inventor of the invention found in the research that in the normal pressure distillation process, inactive gas is sprayed above the liquid level of the crude latex, the gas can carry solvent to be distilled out together, and the continuous discharge of the gas takes away a large amount of solvent steam, so that foam generated in the distillation is eliminated in time, the solvent diffusion efficiency is improved, and the solvent removal time is shortened.
The inventors of the present invention have further found in the study that the solvent can be removed for the vast majority of the crude latex by atmospheric distillation as described above. And whether or not distillation under reduced pressure is performed to further remove a small amount of the residual solvent may be selected according to the requirements of the product.
According to the present invention, the amount of inactive gas sprayed is preferably 0.1 to 10L, more preferably 0.5 to 5L, most preferably 1 to 2L per liter of the raw latex. The inventor of the present invention found in the research that when the volume ratio is satisfied, the purpose of eliminating foam generated in the distillation process in time, improving the solvent transfer rate and shortening the solvent removal time can be achieved without introducing more gas. According to the invention, the process can be carried out continuously, the raw latex being fed in a continuous manner, the inactive gas being dispersed in a continuous manner, the ratio between the feeding rate of the raw latex and the dispersing rate of the inactive gas preferably being 1:0.1 to 10, more preferably 1:0.5 to 5, most preferably 1:1-2.
According to the present invention, the inert gas may be selected as usual in the art, as long as it is non-toxic and does not react with the raw latex, but preferably, the inert gas is nitrogen, inert gas, air and CO 2 At least one of them. In the normal pressure distillation process, the gas is selected, so that the solvent can be carried and distilled out, and the environment pollution is avoided.
According to the invention, the temperature of the inert gas is preferably from 0 ℃ to 50 ℃, more preferably from 5 ℃ to 30 ℃, most preferably from 10 ℃ to 20 ℃.
According to the present invention, the inert gas spraying pressure is preferably 0.1MPa to 1MPa, more preferably 0.2MPa to 0.8MPa, and most preferably 0.3MPa to 0.6MPa.
It will be appreciated that the temperature of the material is relatively high during atmospheric distillation. The inventor of the invention discovers in the research that when the temperature and pressure range of the inactive gas are satisfied, the foam in the kettle body can be broken, the solvent vapor in the foam can be released in time, the solvent vapor can not be condensed instantaneously due to the lower temperature of the inactive gas, and the solvent can be evaporated conveniently.
According to the present invention, in order to further ensure timely elimination of foam generated during distillation, it is preferable that the inert gas is sprayed through a cylindrical tube with fine holes having a density of 50 to 2000 mesh, more preferably 100 to 1000 mesh, and most preferably 200 to 600 mesh. It can be understood that the inert gas is ejected from each of the fine holes of the cylindrical tube.
According to the present invention, it is preferable that the conditions of the atmospheric distillation are such that the solvent removed by the atmospheric distillation accounts for 80 to 99% by volume, more preferably 90 to 97% by volume, and most preferably 93 to 96% by volume of the total amount of the solvent in the crude latex. It will be appreciated that the longer the material residence time in the atmospheric distillation still, the more solvent is removed. In order to achieve the above solvent removal, the atmospheric distillation is generally completed with a residence time of 1 to 20 hours, or 3 to 15 hours, or 6 to 8 hours.
According to the present invention, it is preferable that the conditions of the reduced pressure distillation are such that the solvent removed by the reduced pressure distillation accounts for 1 to 20% by volume, more preferably 3 to 10% by volume, most preferably 4 to 7% by volume of the total amount of the solvent in the crude latex. In order to achieve the above solvent removal, the distillation under reduced pressure is generally carried out for a residence time of 0.2 to 4 hours, or 0.5 to 3 hours, or 1 to 2 hours.
According to the present invention, it is preferred that the difference between the temperature of atmospheric distillation and the boiling point of the solvent in the crude latex is from 0 ℃ to 20 ℃, more preferably from 3 ℃ to 15 ℃, most preferably from 5 ℃ to 8 ℃. It will be appreciated that the temperature of the atmospheric distillation is higher than the boiling point of the solvent in the crude latex. The inventor of the present invention further found in the research that when the above range is satisfied, the solvent can be distilled off faster, the solvent distillation time is shortened, the material is not boiled, and the operation is safer.
According to the present invention, the pressure of the reduced pressure distillation is preferably 0.05MPa to 0.0001MPa, more preferably 0.01MPa to 0.001MPa, most preferably 0.008MPa to 0.003MPa. The inventors of the present invention have further found in the study that, within the above-mentioned range, the removal of the residual solvent is more facilitated.
According to the present invention, in order to further remove the residual solvent in the material after atmospheric distillation, it is preferable that the difference between the temperature of the reduced pressure distillation and the boiling point of the solvent in the crude latex is 0 to 20 ℃, more preferably 2 to 15 ℃, and most preferably 3 to 10 ℃.
According to the present invention, it is preferable that the stirring speeds of the atmospheric distillation and the vacuum distillation are each independently 100rpm to 2000rpm, more preferably 300rpm to 1600rpm, and most preferably 600rpm to 1200rpm. The inventor of the present invention found in the research that, in the above-mentioned range, not only the latex material can be completely turbulent, the solvent transmission rate is increased, the distillation time is shortened, but also the free emulsifier in the material can be combined with the demulsified rubber molecules more quickly to form new latex particles, and the demulsification is reduced.
According to the invention, the solvent content of the coarse latex is preferably 30% to 70%, more preferably 40% to 55%, most preferably 42% to 50% by volume.
According to the invention, the polyisoprene is preferably present in the coarse latex in an amount of 2% to 10% by weight, more preferably 3% to 8% by weight, most preferably 4% to 6% by weight.
According to the invention, the weight content of emulsifier in the coarse latex is preferably 0.5% -10%, preferably 1% -5%, most preferably 1.5% -4%.
According to the present invention, preferably, the solvent in the crude latex is a saturated aliphatic hydrocarbon and/or an alicyclic hydrocarbon, more preferably at least one of n-hexane, cyclohexane, methylcyclopentane, n-heptane, n-pentane and cyclopentane.
According to the invention, it is preferred that the polyisoprene in the coarse latex has a number average molecular weight of 1 to 100 thousand g/mol, more preferably 10 to 50 thousand g/mol, most preferably 20 to 35 thousand g/mol.
The specific substances of the emulsifier are not particularly limited, and the method provided by the invention is wide in application range. Preferably, however, the emulsifier in the coarse latex is an anionic emulsifier and/or a nonionic emulsifier. Wherein the anionic emulsifier can be C12-C30 fatty acid salt, alkylbenzene sulfonate, alkyl sulfate salt, such as sodium alkylbenzenesulfonate series, oleate series, laurate series, abietate series, linolenate series, etc.; the nonionic emulsifier can be C8-C24 ether, alcohol, or ester emulsifier, such as fatty alcohol polyoxyethylene ether series, SPAN series, tween series, etc.
According to the invention, the atmospheric distillation and the vacuum distillation can be carried out in the same kettle or can be carried out separately in different kettles. However, for the sake of convenience in operation, it is preferable that the atmospheric distillation is performed in an atmospheric distillation still, the reduced pressure distillation is performed in a reduced pressure distillation still, the atmospheric distillation still and the reduced pressure distillation still are each provided with a feed port, a solvent outlet and a discharge port, and the discharge port of the atmospheric distillation still is connected to the feed port of the reduced pressure distillation still.
According to the present invention, it is preferable that the volume ratio of the atmospheric still to the vacuum still is 1 to 20, more preferably 3 to 15, and most preferably 5 to 8.
According to the invention, preferably, the atmospheric distillation kettle and the vacuum distillation kettle are respectively provided with a heat exchange jacket, a heat exchange medium inlet of the heat exchange jacket is arranged at the bottom of the heat exchange jacket, and a heat exchange medium outlet is arranged at the top of the heat exchange jacket. The arrangement of the jacket is more beneficial to controlling the distillation temperature in the kettle body.
According to the invention, for further convenient operation, it is preferable that the feed inlet of the atmospheric distillation kettle is positioned at the bottom of the kettle body, the solvent outlet is positioned at the top of the kettle body, the discharge outlet is positioned at the middle upper part of the kettle body, and the ratio between the height of the discharge outlet and the height of the kettle body is 0.5-1, more preferably 0.6-0.9, and most preferably 0.7-0.8.
According to the present invention, in order to further increase the solvent transfer rate and shorten the solvent removal time, it is preferable that each of the atmospheric distillation still and the vacuum distillation still is provided with a stirring unit including a stirring shaft and at least one stirring paddle vertically arranged and fixed on the stirring shaft, the number of stirring paddles is preferably 1 to 10, more preferably 2 to 8, and most preferably 3 to 5. The stirring paddles can be paddle stirring paddles which are distributed on the stirring shaft at equal intervals. The inventors of the present invention have further found that a fine-meshed cylindrical tube can be fixed to a stirring shaft, so that inactive gas can be sprayed while the cylindrical tube is rotated along with the stirring shaft without interfering with the operation of the stirring unit.
The invention also provides a device for removing the organic solvent, which comprises: the atmospheric distillation kettle and the optional reduced pressure distillation kettle are respectively provided with a feed inlet, a solvent outlet and a discharge outlet, and the discharge outlet of the atmospheric distillation kettle is connected with the feed inlet of the reduced pressure distillation kettle.
Preferably, the gas dispersion member is a cylindrical tube with fine holes having a density of 50 to 2000 mesh, more preferably 100 to 1000 mesh, and most preferably 200 to 600 mesh.
Preferably, the volume ratio of the atmospheric distillation still to the vacuum distillation still is from 1 to 20, more preferably from 3 to 15, most preferably from 5 to 8.
Preferably, the atmospheric distillation kettle and the reduced pressure distillation kettle are respectively provided with a heat exchange jacket, a heat exchange medium inlet of the heat exchange jacket is arranged at the bottom of the heat exchange jacket, and a heat exchange medium outlet is arranged at the top of the heat exchange jacket.
Preferably, the feed inlet of the atmospheric distillation kettle is positioned at the bottom of the kettle body, the solvent outlet is positioned at the top of the kettle body, the discharge outlet is positioned at the middle upper part of the kettle body, and the ratio between the height of the discharge outlet and the height of the kettle body is 0.5-1, more preferably 0.6-0.9, and most preferably 0.7-0.8.
Preferably, the feed inlet of the reduced pressure distillation still is positioned at the bottom of the still body, the solvent outlet is positioned at the top of the still body, the discharge outlet is positioned at the middle upper part of the still body, and the ratio between the height of the discharge outlet and the height of the still body is 0.5-1, more preferably 0.6-0.9, and most preferably 0.7-0.8.
Preferably, each of the atmospheric distillation still and the vacuum distillation still is provided with a stirring unit, the stirring unit comprises a stirring shaft and at least one stirring paddle which is fixed on the stirring shaft and is vertically arranged, and the number of the stirring paddles is preferably 1-10, more preferably 2-8, and most preferably 3-5. The stirring paddles can be paddle stirring paddles which are distributed on the stirring shaft at equal intervals.
It will be appreciated that a vacuum control system may also be provided on the reduced pressure still for controlling the pressure within the reduced pressure still.
The method for producing the crude latex of the present invention is not particularly limited, and the method of CN109929123a can be adopted. However, according to a preferred embodiment of the present invention, the method for preparing polyisoprene latex (raw latex) includes the steps of exerting emulsifying ability of an emulsifier as much as possible, reducing viscosity of a latex mixture, reducing loss of molecular weight of rubber, preparing raw latex having higher molecular weight, and having higher mechanical properties, higher mechanical stability and better film forming property.
(1) Mixing polyisoprene dry adhesive with nonionic emulsifier solution for pre-emulsification;
(2) And (3) premixing and emulsifying the mixture obtained in the step (1) and an anionic emulsifier in sequence.
The inventor of the invention finds that firstly, polyisoprene dry rubber is dissolved in nonionic emulsifier solution, polyisoprene can be more uniformly dispersed together with nonionic emulsifier, the combination is better, meanwhile, due to the existence of aqueous solution, the interaction force between rubber molecular chains is better weakened, the rubber molecular chains are less broken in the subsequent emulsification, the rubber molecular chains can be better protected, the loss of molecular weight is reduced, the emulsifying capacity of the emulsifier is exerted as much as possible, and then pre-emulsification, pre-mixing and emulsification are sequentially carried out, so that the polyisoprene latex with higher molecular weight, higher mechanical property, higher mechanical stability and better film forming property can be obtained.
According to the present invention, in order to further exert the emulsifying ability of the nonionic emulsifier, the nonionic emulsifier is preferably used in an amount of 0.5 to 5% by mass, more preferably 0.8 to 3% by mass, and most preferably 1 to 2.5% by mass of the polyisoprene dry gel in the nonionic emulsifier solution, to better protect the rubber molecular chain and reduce the loss of molecular weight.
According to the present invention, in order to further exert the emulsifying ability of the emulsifier, it is preferable that the mass amount of the anionic emulsifier is 5% to 50%, more preferably 8% to 40%, still more preferably 10% to 30% of the mass of the polyisoprene dry adhesive.
According to the present invention, it is preferable that the content of cis-1, 4-polyisoprene structure in the polyisoprene dry adhesive is not less than 95% by mass, and the number average molecular weight of the polyisoprene in the polyisoprene dry adhesive is 15 to 40 ten thousand g/mol, more preferably 18 to 30 ten thousand g/mol, and most preferably 20 to 23 ten thousand g/mol. The synthetic method of the polyisoprene is not particularly limited, and the polyisoprene can be prepared through rare earth catalysis. When the content of the cis-1, 4-polyisoprene structure is satisfied, the prepared polyisoprene latex can be further ensured to have higher adhesive film tensile strength and adhesive film elongation at break.
According to the present invention, it is preferable that the mass concentration of the nonionic emulsifier in the nonionic emulsifier solution is 0.01% to 1%, more preferably 0.12% to 0.5%, and most preferably 0.15% to 0.4%.
According to the present invention, in order to further exert the emulsifying ability of the nonionic emulsifier, which is preferably at least one of C8-C24 ether, C8-C24 alcohol and C8-C24 ester, preferably at least one of fatty alcohol polyoxyethylene ether, SPAN and Tween, more preferably sorbitan monooleate (for example, SPAN-80, which may be commercially available), and/or polyoxyethylene sorbitan ether monostearate (for example, tween-61, which may be commercially available), is preferable, the loss of molecular weight is reduced.
According to the present invention, the solvent in the nonionic emulsifier solution is not particularly limited as long as it can ensure dissolution of the polyisoprene dry adhesive, but is preferably at least one of n-hexane, cyclohexane, methylcyclopentane, n-heptane, n-pentane and cyclopentane in view of price, environmental protection and subsequent removal.
According to the present invention, the conditions of the pre-emulsification are not particularly limited as long as it is possible to ensure that the mixture obtained after the pre-emulsification exhibits a uniform transparent shape. But preferably, the temperature of the pre-emulsification is from 10 ℃ to 80 ℃, more preferably from 20 ℃ to 70 ℃, more preferably from 30 ℃ to 60 ℃; the pre-emulsification time is 1h-24h, more preferably 2h-15h, most preferably 3-10h; the pre-emulsification is carried out under stirring at a rotational speed of 100rpm to 2000rpm, more preferably 500rpm to 1500rpm, still more preferably 700rpm to 1000rpm. Within the above-mentioned ranges, in particular within the temperature range, it is further ensured that the polyisoprene dry adhesive is dissolved as completely as possible. In order to further ensure that the polyisoprene dry adhesive is dissolved as much as possible, the polyisoprene dry adhesive can be cut into small pieces and then pre-emulsified. For example, a nonionic emulsifier is added to a container containing a solvent, stirred until dissolved, and then the polyisoprene dry adhesive is cut into small pieces and added to the container.
According to the present invention, it is preferable that the anionic emulsifier is used in the form of an anionic emulsifier aqueous solution in which the mass concentration of the anionic emulsifier is 0.1% to 10%, more preferably 1.2% to 5%, most preferably 1.5% to 4%.
According to the present invention, in order to further exert the emulsifying ability of the emulsifier, it is preferable that the pH of the anionic emulsifier aqueous solution is 9 to 15, more preferably 10 to 14, and most preferably 11 to 13. Wherein the pH can be controlled by using inorganic bases, such as KOH and/or NaOH.
According to the present invention, in order to further exert the emulsifying ability of the emulsifier, it is preferable that the anionic emulsifier is at least one of a fatty acid salt of C12 to C30, an alkylbenzenesulfonic acid salt of C12 to C30, and an alkylsulfate salt of C12 to C30, more preferably at least one of sodium alkylbenzenesulfonate, oleate, laurate, abietate, and linolenate, still more preferably at least one of sodium dodecylbenzenesulfonate and potassium disproportionated abietate.
According to the present invention, preferably, the premixing method includes: adding an aqueous anionic emulsifier solution to the mixture at a rate of from 1% by volume/min to 50% by volume/min, more preferably from 2% by volume/min to 20% by volume/min, most preferably from 3% by volume/min to 10% by volume/min, based on the volume of the aqueous anionic emulsifier solution; the premixing is carried out under stirring conditions at a rotation speed of 100rpm to 3000rpm, more preferably 300rpm to 2000rpm, most preferably 500rpm to 1000rpm; the temperature of the premixing is from 10 ℃ to 80 ℃, more preferably from 20 ℃ to 70 ℃, and even more preferably from 30 ℃ to 60 ℃. It will be appreciated that if the volume of the aqueous anionic emulsifier solution is 1000ml, 50ml (i.e. 1000ml 5%) of the aqueous anionic emulsifier solution is added per minute when added at an addition rate of 5% by volume/min. Wherein the temperature of the premixing can be achieved by controlling the temperature of the aqueous solution of the anionic emulsifier. The inventors of the present invention have also found in the study that as the amount of the aqueous solution of the anionic emulsifier increases, the material forms a W/O type (water-in-oil) emulsion first and then gradually changes into an O/W type (oil-in-water) emulsion; further, when the above-mentioned range, particularly the range of the addition rate of the aqueous solution of the anionic emulsifier is satisfied, the stability of the latex can be further increased.
According to the present invention, the emulsifying means is preferably mechanical emulsification, and the stirring speed of the mechanical emulsification is 1000rpm to 10000rpm, more preferably 2500rpm to 8000rpm, and most preferably 3500rpm to 7000rpm.
According to the invention, the time of the emulsification is preferably 2min-30min, more preferably 5min-20min, most preferably 7min-15min.
According to the present invention, the temperature of emulsification is preferably 10 ℃ to 60 ℃, more preferably 20 ℃ to 55 ℃, and even more preferably 30 ℃ to 50 ℃.
The inventors of the present invention found that emulsification can be better achieved when the rotational speed, temperature and time ranges as described above are satisfied.
The method of the invention can also comprise the step of removing the solvent from the emulsified product, wherein the solvent removal can be carried out in a conventional manner and is not described herein.
The invention also provides polyisoprene latex prepared by the method.
According to the present invention, it is preferable that the number average molecular weight of the polyisoprene latex is 15 to 40 ten thousand g/mol, more preferably 18 to 30 ten thousand g/mol, and most preferably 20 to 23 ten thousand g/mol.
According to the invention, the particle size of the polyisoprene latex is preferably from 100nm to 2000nm, more preferably from 200 to 1500nm, most preferably from 300 to 1200nm.
According to the present invention, it is preferable that the tensile strength of the polyisoprene latex is 15MPa to 30MPa, more preferably 18MPa to 25MPa, and most preferably 20MPa to 22MPa.
According to the present invention, the polyisoprene latex preferably has an elongation at break of 700% to 1500%, more preferably 900% to 1300%, most preferably 1000% to 1200%.
According to the present invention, the polyisoprene latex has a concentration of polyisoprene in mass of 40 to 80% by mass, more preferably 50 to 70% by mass, still more preferably 55 to 65% by mass.
The present invention will be described in detail by examples.
In the following examples and comparative examples, the organic solvent in the crude latex was removed using the apparatus described below:
as shown in fig. 1, the apparatus includes an atmospheric distillation still 13 and a vacuum distillation still 14.
The volume of the atmospheric distillation kettle was 200L (the volume below the discharge port level, i.e., the effective volume of the kettle). The atmospheric distillation kettle 13 has a height of 1m, is provided with an atmospheric distillation kettle feed inlet 3 positioned at the bottom of the kettle body, an atmospheric distillation kettle solvent outlet 6 positioned at the top of the kettle body and an atmospheric distillation kettle discharge outlet 7 positioned at the middle upper part of the kettle body and having a height of 0.7 m.
The volume of the reduced pressure distillation still 14 was 30L (the volume below the level of the discharge port, i.e., the effective volume of the still) and the height was 0.56m. The vacuum distillation still 13 is provided with a vacuum distillation still feed inlet 15 positioned at the bottom of the still body, a vacuum distillation still solvent outlet 11 positioned at the top of the still body and a vacuum distillation still discharge outlet 10 positioned at the middle upper part of the still body and having a height of 0.4 m.
The discharge port 7 of the atmospheric distillation kettle is connected with the feed port 15 of the vacuum distillation kettle. And, the atmospheric distillation kettle 13 and the reduced pressure distillation kettle 14 are respectively provided with a heat exchange jacket, a heat exchange medium inlet of the heat exchange jacket is arranged at the bottom of the heat exchange jacket, and a heat exchange medium outlet is arranged at the top of the heat exchange jacket. The heating medium of the atmospheric distillation kettle 13 enters from the heating medium inlet 4 of the atmospheric distillation kettle and is discharged from the heating medium outlet 5 of the atmospheric distillation kettle; the heating medium of the vacuum distillation still 14 enters from the vacuum distillation still heating medium inlet 8 and is discharged from the vacuum distillation still heating medium outlet 9.
The normal pressure distillation still and the reduced pressure distillation still are respectively provided with a stirring unit, and each stirring unit comprises a stirring shaft and 3 stirring paddles (the 3 stirring paddles are distributed at equal intervals) which are fixed on the stirring shaft and are vertically arranged. A cylindrical tube 1 with fine holes with the density of 300 meshes is also fixed on the stirring shaft of the atmospheric distillation kettle.
Wherein, install the ooff valve in order to make things convenient for the break-make of control material pipeline on each material pipeline that is used for carrying the material. And a flowmeter is arranged on the material pipeline. And steam is introduced into jackets of the atmospheric distillation still and the vacuum distillation still to control the respective required temperatures of the atmospheric distillation still and the vacuum distillation still.
In the following examples and comparative examples, the amounts of residual solvent in latex and the gel loss ratio in the products after removal of the atmospheric distillation and after distillation under reduced pressure were calculated as follows:
the method for calculating the residual solvent of the latex comprises the following steps: demulsification is carried out on the materials by using absolute ethyl alcohol, then surface moisture is washed by using absolute ethyl alcohol for multiple times, the absolute ethyl alcohol on the surface is removed by air drying for 5 hours at normal temperature, and then the materials are dried (the drying temperature is 75+/-2 ℃ C. And the drying time is 12 hours), and the materials are subjected to drying treatment according to the calculation formula w= [ (m) 0 -m 1 )/m 0 ]×10 6 Wherein w is the residual amount of solvent, ppm; m is m 0 The quality of the colloidal particles after air drying; m is m 1 The quality of the dried colloidal particles is that of the dried colloidal particles; the residual solvent content of the latex was obtained.
Gel loss ratio: taking materials, sieving with 200 mesh sieve, repeatedly washing the filtered coagulum, oven drying (drying temperature is 75+ -2deg.C for 12 h), and collecting the filtrate according to j= [ m ] 1 /(m 0 ×p+m 1 )]X 100, wherein j is the gel loss ratio; m is m 0 The mass of the thin latex before drying is g; the unit is g, which is the mass of the dried gel; and p is the mass percent of the latex in the dilute latex before drying, and the gel loss ratio in the distillation process of the crude latex is obtained.
Example 1
Coarse latex: contains 45% by volume of n-hexane (boiling point of n-hexane is 69 ℃); the polyisoprene content was 5 wt%, the number average molecular weight was 20 ten thousand g/mol; the emulsifier is a mixture of anionic emulsifier sodium dodecyl benzene sulfonate and disproportionated potassium abietate, and the content is 2 wt%.
Steam was introduced to maintain the atmospheric still at 74℃and the stirring unit was turned on in the atmospheric still at 800rpm, and the crude latex was added to the atmospheric still at 40L/h. In the atmospheric distillation kettle, the inactive gas sprayed to the upper part of the liquid level of the crude latex is N 2 The temperature of the ejected gas was 15 ℃, the gas ejection pressure was 0.4MPa, and the flow rate was 60L/h. The crude latex was left in the atmospheric distillation still until, after atmospheric distillation, the solvent remaining in the mass was 6% by volume of the total amount of solvent in the crude latex, at which time the residence time of the crude latex in the atmospheric distillation still was6.5 hours, the gel loss ratio of the material after atmospheric distillation is 4%.
The material flowing out of the atmospheric distillation kettle was introduced into a reduced pressure distillation kettle at a rate of 21.8L/h. The temperature in the reduced pressure distillation still was maintained at 76℃by steam, the pressure in the still was controlled at 0.005MPa, and the rotational speed was 1000rpm. The crude latex remained in the reduced pressure distillation kettle until the residual solvent in the material accounts for 0.4 volume percent of the total solvent in the crude latex after reduced pressure distillation, the retention time of the material in the reduced pressure distillation kettle is 1.4h, and the gel loss ratio after reduced pressure distillation is 0.1 percent.
Example 2
Coarse latex: contains 50% by volume of n-hexane (boiling point of n-hexane is 69 ℃); the polyisoprene content was 6 wt%, the number average molecular weight was 31 ten thousand g/mol; the emulsifier is nonionic emulsifier polyoxyethylene alcohol series (purchased from national drug group) with a content of 1.5 wt%.
Steam was introduced to maintain the atmospheric still at 77℃and the stirring unit was turned on in the atmospheric still at 1000rpm, and the crude latex was added to the atmospheric still at 44L/h. In the atmospheric distillation kettle, the inactive gas sprayed to the upper part of the liquid level of the crude latex is N 2 The temperature of the ejected gas was 10 ℃, the gas ejection pressure was 0.3MPa, and the flow rate was 88L/h. The crude latex remained in the atmospheric distillation kettle until the residual solvent in the material accounts for 7% of the total solvent in the crude latex after atmospheric distillation, the residence time of the crude latex in the atmospheric distillation kettle is 6h, and the gel loss ratio of the material after atmospheric distillation is 4.5% according to the test.
The material flowing out of the atmospheric distillation kettle was introduced into a reduced pressure distillation kettle at a rate of 22.1L/h. The temperature in the reduced pressure distillation still was maintained at 74℃by steam, the pressure in the still was controlled at 0.004MPa, and the rotational speed was 600rpm. The crude latex remained in the reduced pressure distillation kettle until the residual solvent in the material accounts for 0.4 volume percent of the total solvent in the crude latex after reduced pressure distillation, the retention time of the material in the reduced pressure distillation kettle is 1.4h, and the gel loss ratio after reduced pressure distillation is 0.1 percent.
Example 3
Coarse latex: contains 42% by volume of n-hexane (boiling point of n-hexane is 69 ℃); the polyisoprene content was 4 wt%, the number average molecular weight was 35 ten thousand g/mol; the emulsifier is a mixture of anionic emulsifier disproportionated potassium abietate and nonionic emulsifier SPAN80, and the total content of the emulsifier is 3 wt%.
Steam was introduced to maintain the atmospheric still at 75℃and the stirring unit was turned on in the atmospheric still at 1200rpm, and the crude latex was added to the atmospheric still at 32L/h. In the atmospheric distillation kettle, the inactive gas sprayed to the upper part of the liquid level of the crude latex is N 2 The temperature of the ejected gas was 20 ℃, the gas ejection pressure was 0.5MPa, and the flow rate was 32L/h. The crude latex remained in the atmospheric distillation kettle until the residual solvent in the material accounts for 4.5 volume percent of the total solvent in the crude latex after atmospheric distillation, the residence time of the crude latex in the atmospheric distillation kettle is 8 hours, and the gel loss ratio of the material after atmospheric distillation is 5 percent.
And (3) introducing the materials flowing out of the atmospheric distillation kettle into a reduced pressure distillation kettle, wherein the introducing speed is 18L/h. The temperature in the reduced pressure distillation kettle is maintained at 72 ℃ by steam, the pressure in the kettle is controlled at 0.003MPa, and the rotating speed is 1200rpm. The crude latex remained in the reduced pressure distillation kettle until the residual solvent in the material accounts for 0.5 volume percent of the total solvent in the crude latex after reduced pressure distillation, the retention time of the material in the reduced pressure distillation kettle is 1.7h, and the gel loss ratio after reduced pressure distillation is 0.2 percent.
Example 4
Coarse latex: contains 48 volume% of n-hexane (boiling point of n-hexane is 69 ℃); the polyisoprene content was 5 wt%, the number average molecular weight was 25 ten thousand g/mol; the emulsifier is anionic emulsifier sodium benzenesulfonate series (purchased from national drug group) with content of 4wt%.
Steam was introduced to maintain the atmospheric still at 75℃and the stirring unit was turned on in the atmospheric still at 600rpm, and the crude latex was added to the atmospheric still at a rate of 35L/h. In the atmospheric distillation kettle, the inactive gas sprayed to the upper part of the liquid level of the crude latex is N 2 The temperature of the sprayed gas is 12 ℃, and the gas is sprayedThe pressure was 0.6MPa and the flow rate was 50L/h. The crude latex remained in the atmospheric distillation kettle until, after atmospheric distillation, the residual solvent in the material accounted for 5% by volume of the total solvent in the crude latex, at this time, the residence time of the crude latex in the atmospheric distillation kettle was 7.6h, and the gel loss ratio of the material after atmospheric distillation was found to be 4.8%.
The material flowing out of the atmospheric distillation kettle was introduced into a reduced pressure distillation kettle at a rate of 17.8L/h. The temperature in the reduced pressure distillation still was maintained at 79℃by steam, the pressure in the still was controlled at 0.008MPa, and the rotational speed was 800rpm. The crude latex remained in the reduced pressure distillation kettle until the residual solvent in the material accounts for 0.2 volume percent of the total solvent in the crude latex after reduced pressure distillation, the retention time of the material in the reduced pressure distillation kettle is 1.8h, and the gel loss ratio after reduced pressure distillation is 0.2 percent.
Example 5
Coarse latex: contains 55% by volume of n-hexane (boiling point of n-hexane is 69 ℃); the polyisoprene content was 3 wt%, the number average molecular weight was 10 ten thousand g/mol; the emulsifier is anionic emulsifier potassium oleate and disproportionated potassium abietate, and the content is 3.5 wt%.
Steam was introduced to maintain the atmospheric still at 72℃and the stirring unit was turned on in the atmospheric still at 300rpm, and the crude latex was added to the atmospheric still at a rate of 35L/h. In the atmospheric distillation kettle, the inactive gas sprayed to the upper part of the liquid level of the crude latex is N 2 The temperature of the ejected gas was 30 ℃, the gas ejection pressure was 0.2MPa, and the flow rate was 17.5L/h. The crude latex remained in the atmospheric distillation kettle until, after atmospheric distillation, the residual solvent in the material accounted for 10% by volume of the total solvent in the crude latex, at this time, the residence time of the crude latex in the atmospheric distillation kettle was 7h, and the gel loss ratio of the material after atmospheric distillation was found to be 4.9%.
And (3) introducing the materials flowing out of the atmospheric distillation kettle into a reduced pressure distillation kettle, wherein the introducing speed is 16L/h. The temperature in the reduced pressure distillation still is maintained at 71 ℃ by steam, the pressure in the still is controlled at 0.01MPa, and the rotating speed is 1600rpm. The crude latex remained in the reduced pressure distillation kettle until the residual solvent in the material accounts for 7.5 volume percent of the total solvent in the crude latex after reduced pressure distillation, the retention time of the material in the reduced pressure distillation kettle is 1.5h, and the gel loss ratio after reduced pressure distillation is 0.5 percent.
Example 6
Coarse latex: contains 40% by volume of n-hexane (boiling point of n-hexane is 69 ℃); the polyisoprene content was 8 wt%, the number average molecular weight was 50 ten thousand g/mol; the emulsifier is an anionic emulsifier benzenesulfonic acid series (purchased from national drug group) with a content of 2.5 wt%.
Steam was introduced to maintain the atmospheric still at 84℃and the stirring unit was turned on in the atmospheric still at 1600rpm, and the crude latex was added to the atmospheric still at a rate of 35L/h. In the atmospheric distillation kettle, the inactive gas sprayed to the upper part of the liquid level of the crude latex is N 2 The temperature of the ejected gas was 5 ℃, the gas ejection pressure was 0.8MPa, and the flow rate was 175L/h. The crude latex remained in the atmospheric distillation kettle until the residual solvent in the material accounts for 3 volume percent of the total solvent in the crude latex after the atmospheric distillation, the residence time of the crude latex in the atmospheric distillation kettle is 8 hours, and the gel loss ratio of the material after the atmospheric distillation is 4.4 percent.
And (3) introducing the materials flowing out of the atmospheric distillation kettle into a reduced pressure distillation kettle, wherein the introducing speed is 16L/h. The temperature in the reduced pressure distillation still was maintained at 84℃by steam, the pressure in the still was controlled at 0.001MPa, and the rotational speed was 300rpm. The crude latex remained in the reduced pressure distillation kettle until the residual solvent in the material accounts for 0.2 volume percent of the total solvent in the crude latex after reduced pressure distillation, the retention time of the material in the reduced pressure distillation kettle is 1h, and the gel loss ratio after reduced pressure distillation is 0.7 percent.
Example 7
The organic solvent was removed as in example 3, except that the amount of inactive gas sprayed per liter of the crude rubber latex was 0.1L, the temperature of the inactive gas was 0℃and the pressure of the inactive gas sprayed was 0.1MPa. After the crude latex stays in the atmospheric distillation kettle for 8 hours, a sample in the atmospheric distillation kettle is taken, and the test shows that the residual solvent in the material accounts for 5.2 volume percent of the total solvent in the crude latex, and the gel loss ratio is 6 percent.
And (3) introducing the material which is left in the normal pressure distillation kettle for 6 hours into a reduced pressure distillation kettle, stopping reduced pressure distillation after the material is left in the reduced pressure distillation kettle for 1.7 hours, sampling, and testing to find that the residual solvent in the material accounts for 1 volume percent of the total solvent in the crude latex, and the gel loss ratio is 0.5 percent.
Example 8
The organic solvent was removed as in example 3, except that instead of spraying the inert gas through a cylindrical tube with fine holes, an air inlet was opened above the atmospheric distillation still, through which the inert gas was sprayed.
After the crude latex stays in the atmospheric distillation kettle for 8 hours, a sample in the atmospheric distillation kettle is taken, and the test shows that the residual solvent in the material accounts for 6 volume percent of the total solvent in the crude latex, and the gel loss ratio is 7 percent.
The material after 6h of stay in the atmospheric distillation kettle is introduced into a reduced pressure distillation kettle, the reduced pressure distillation is stopped after the material stays in the reduced pressure distillation kettle for 1.7h, and the sample is sampled, and the test shows that the residual solvent in the material accounts for 1.5 volume percent of the total solvent in the crude latex, and the gel loss ratio is 1%.
Comparative example 1
The organic solvent was removed as in example 1, except that no N was present in the atmospheric distillation kettle 2 And (5) spraying. After the crude latex stays in the atmospheric distillation kettle for 6.5 hours, a sample in the atmospheric distillation kettle is taken, and the test shows that the residual solvent in the material accounts for 23 volume percent of the total solvent in the crude latex, and the gel loss ratio is 8 percent.
The material which remained in the atmospheric distillation kettle for 6.5 hours was introduced into the vacuum distillation kettle, and after the material remained in the vacuum distillation kettle for 1.4 hours, the sample was sampled, and the test found that the residual solvent in the material was 4.4% by volume of the total amount of the solvent in the crude latex, and the gel loss ratio was 1%.
Comparative example 2
The organic solvent was removed as in example 2, except that no N was present in the atmospheric distillation kettle 2 And (5) spraying. After the crude latex stays in the atmospheric distillation kettle for 6 hours, a sample in the atmospheric distillation kettle is taken, and the test shows that the residual solvent in the materials accounts for the total solvent in the crude latex25% by volume of the amount and the gel loss ratio was 8%.
The material after 6h of stay in the atmospheric distillation kettle is introduced into a reduced pressure distillation kettle, and after 1.4h of stay in the reduced pressure distillation kettle, the sample is sampled, and the test shows that the residual solvent in the material accounts for 4.5 volume percent of the total solvent in the crude latex, and the gel loss ratio is 1 percent.
Comparative example 3
The organic solvent was removed as in example 3, except that no N was present in the atmospheric distillation kettle 2 And (5) spraying. After the crude latex stays in the atmospheric distillation kettle for 8 hours, a sample in the atmospheric distillation kettle is taken, and the test shows that the residual solvent in the material accounts for 15 volume percent of the total solvent in the crude latex, and the gel loss ratio is 12 percent.
The material after 8h of stay in the atmospheric distillation kettle is introduced into a reduced pressure distillation kettle, and after 1.7h of stay in the reduced pressure distillation kettle, the sample is sampled, and the test shows that the residual solvent in the material accounts for 2 volume percent of the total solvent in the crude latex, and the gel loss ratio is 1.5 percent.
Comparative example 4
The organic solvent was removed as in example 4, except that no N was present in the atmospheric distillation kettle 2 And (5) spraying. After the crude latex stays in the atmospheric distillation kettle for 7.6 hours, a sample in the atmospheric distillation kettle is taken, and the test shows that the residual solvent in the material accounts for 17 percent by volume of the total solvent in the crude latex, and the gel loss ratio is 10 percent.
The materials which remained in the atmospheric distillation kettle for 7.6 hours are introduced into a reduced pressure distillation kettle, the materials are sampled after staying in the reduced pressure distillation kettle for 1.8 hours, and the test shows that the residual solvent in the materials accounts for 2 volume percent of the total solvent in the crude latex, and the gel loss ratio is 1.5 percent.
As can be seen from the above examples and comparative examples, the examples 1 to 8 adopting the technical scheme of the present invention can obtain better solvent removal effect in a shorter time, shorten solvent removal time, and have lower gel loss ratio, i.e. obviously reduce demulsification. Wherein examples 1-4 are more effective.
In the following examples of the present invention,
SPAN-80 containing sorbitan monooleate;
tween-61 comprises polyoxyethylene sorbitan monostearate;
the Mooney 70 rubber comprises polyisoprene, wherein the content of cis-1, 4-polyisoprene structure is not less than 95 mass percent, and the number average molecular weight is 22 ten thousand g/mol;
the latex molecular weight test method comprises the following steps: oven drying the latex and measuring by gel permeation liquid chromatography (GPC);
the latex particle size test adopts a Malvern nanometer particle size and Zeta potential analyzer;
the emulsifier pH value test adopts a multifunctional pH meter of S475-LRF;
the mass concentration test of polyisoprene in the polyisoprene latex adopts a thermogravimetric method;
the tensile strength of the adhesive film is tested by GB/T528-1998;
the test method of the elongation at break of the adhesive film is GB/T528-1998;
the latex placement stability was tested by standing and observing that the longer the latex placement stability time, the better the mechanical stability.
Example 9
500g of n-hexane solvent was pressed into a 2L jacketed glass kettle, and 0.75g of the nonionic emulsifier SPAN-80 was added to the glass kettle and stirred until completely dissolved, i.e., the solution appeared to be uniformly transparent to the naked eye. 56g of Mooney 70 rubber is weighed and cut into small blocks, then added into the glass kettle, pre-emulsified is carried out, the stirring speed of the pre-emulsification is 800rpm, the temperature of the pre-emulsification is 60 ℃ by heating a jacket water bath of the glass kettle, and the substances in the kettle form uniform transparent glue solution after stirring for 3 hours.
550g of deionized water is added into a beaker, 11g of sodium dodecyl benzene sulfonate is weighed and added into the beaker, the beaker is placed on a flat plate heater to be heated, a glass rod is used for continuously stirring to enable the emulsifier to be completely dissolved, and a little KOH is added to adjust the pH value to 11.2. The temperature of the solution is controlled to be 50 ℃, the emulsifier solution is slowly added into the glass kettle for premixing, the adding time is 20min, and the stirring rotation speed is controlled to be 500rpm during the adding. After all the addition is completed, the stirring speed is increased to 5000rpm for emulsification, and the polyisoprene coarse latex is obtained after stirring for 10min at 50 ℃. The crude latex in the tank was desolventized and concentrated to give a stable polyisoprene latex at a concentration of 60 wt%.
Example 10
500g of n-hexane solvent was pressed into a 2L jacketed glass kettle, and 1g of non-ionic emulsifier Tween-61 was added into the glass kettle, and stirred until completely dissolved, i.e., the solution appeared to be uniform and transparent to the naked eye. 68g of Mooney 70 rubber is weighed and cut into small blocks, then the small blocks are added into the glass kettle, pre-emulsification is carried out, the stirring speed of the pre-emulsification is 700rpm, the temperature of the pre-emulsification is 30 ℃ by heating a jacket water bath of the glass kettle, and after stirring for 8 hours, the substances in the kettle form uniform transparent glue solution.
660g of deionized water is added into a beaker, 20.4g of disproportionated potassium abietate is weighed and added into the beaker, the beaker is placed on a flat plate heater for heating, a glass rod is used for continuously stirring to enable the emulsifier to be completely dissolved, and a little KOH is added to adjust the pH value to be 12.3. The temperature of the solution is controlled to be 30 ℃, the emulsifier solution is slowly added into the glass kettle for premixing, the adding time is 33min, and the stirring rotation speed is controlled to be 700rpm during the adding. After all the raw materials are added, the stirring speed is increased to 3500rpm for emulsification, the raw materials are stirred at 30 ℃ for 12min to obtain polyisoprene coarse latex, the coarse latex in the kettle is concentrated after the solvent of the coarse latex is removed, and the stable polyisoprene latex with the concentration of 55wt percent is obtained.
Example 11
500g of n-hexane solvent was pressed into a 2L jacketed glass kettle, and 1.5g of the nonionic emulsifier SPAN-80 was added to the glass kettle and stirred until completely dissolved, i.e., the solution appeared to be uniformly transparent to the naked eye. 75g of Mooney 70 rubber is weighed and cut into small blocks, then added into the glass kettle, pre-emulsified is carried out, the stirring speed of the pre-emulsification is 1000rpm, the temperature of the pre-emulsification is 40 ℃ by heating a jacket water bath of the glass kettle, and after stirring for 10 hours, the substances in the kettle form uniform transparent glue solution.
435g of deionized water was added to a beaker, 18.2g of potassium disproportionated rosin was weighed and added to the beaker, the beaker was placed on a flat plate heater and heated, and the emulsifier was completely dissolved by continuous stirring with a glass rod, and a little KOH was added to adjust the pH to 13. The temperature of the solution is controlled to be 40 ℃, the emulsifier solution is slowly added into the glass kettle for 10min, and the stirring rotation speed is controlled to be 1000rpm during the addition. After all the addition is completed, the stirring speed is increased to 7000rpm for emulsification, the mixture is stirred for 15min at 40 ℃ to obtain polyisoprene coarse latex, the coarse latex in the kettle is desolventized and then concentrated to obtain the stable polyisoprene latex with the concentration of 65 wt%.
Example 12
500g of n-hexane solvent was pressed into a 2L jacketed glass kettle, and 2g of non-ionic emulsifier Tween-61 was added into the glass kettle, and stirred until completely dissolved, i.e., the solution appeared to be uniform and transparent to the naked eye. 88g of Mooney 70 rubber is weighed and cut into small blocks, then the small blocks are added into the glass kettle, pre-emulsification is carried out, the stirring speed of the pre-emulsification is 900rpm, the temperature of the pre-emulsification is 45 ℃ by heating a jacket water bath of the glass kettle, and after stirring for 5 hours, the substances in the kettle form uniform transparent glue solution.
Adding 580g of deionized water into a beaker, weighing 21g of sodium dodecyl benzene sulfonate, adding into the beaker, heating the beaker on a flat plate heater, continuously stirring the mixture by using a glass rod to completely dissolve the emulsifier, and adding a little KOH to adjust the pH value to 12.5. The temperature of the solution is 60 ℃ in a thermometer test, the emulsifier solution is slowly added into the glass kettle for premixing, the adding time is 15min, and the stirring rotating speed is controlled at 800rpm during adding. After all the raw materials are added, the stirring speed is increased to 6000rpm for emulsification, the mixture is stirred for 7min at 50 ℃ to obtain polyisoprene coarse latex, the coarse latex in the kettle is concentrated after the solvent of the coarse latex is removed, and the stable polyisoprene latex with the concentration of 63wt percent is obtained.
Example 13
500g of n-hexane solvent was pressed into a 2L jacketed glass kettle, and 0.5g of the nonionic emulsifier SPAN-80 was added to the glass kettle and stirred until completely dissolved, i.e., the solution appeared to be uniformly transparent to the naked eye. 56g of Mooney 70 rubber is weighed and cut into small blocks, then added into the glass kettle, pre-emulsified is carried out, the stirring speed of the pre-emulsification is 500rpm, the jacket of the glass kettle is heated in a water bath to lead the pre-emulsification temperature to be 20 ℃, and after stirring for 15 hours, the substances in the kettle form uniform transparent glue solution.
550g of deionized water is added into a beaker, 8.4g of sodium dodecyl benzene sulfonate is weighed and added into the beaker, the beaker is placed on a flat plate heater for heating, a glass rod is used for continuously stirring to enable the emulsifier to be completely dissolved, and a little KOH is added to adjust the pH value to 10. The temperature of the solution is controlled to be 20 ℃, the emulsifier solution is slowly added into the glass kettle for premixing, the adding time is 50min, and the stirring rotating speed is controlled to be 300rpm during the adding. After all the addition is completed, the stirring speed is increased to 2500rpm for emulsification, and the polyisoprene coarse latex is obtained after stirring for 5min at 20 ℃. The crude latex in the kettle was desolventized and concentrated to give a 62wt% strength stable polyisoprene latex.
Example 14
500g of n-hexane solvent was pressed into a 2L jacketed glass kettle, and 1.68g of the nonionic emulsifier SPAN-80 was added to the glass kettle and stirred until completely dissolved, i.e., the solution appeared to be uniformly transparent to the naked eye. 56g of Mooney 70 rubber is weighed and cut into small blocks, then added into the glass kettle, pre-emulsified is carried out, the stirring speed of the pre-emulsification is 1500rpm, the jacket of the glass kettle is heated in a water bath to lead the pre-emulsification temperature to be 70 ℃, and after stirring for 2 hours, the substances in the kettle form uniform transparent glue solution.
550g of deionized water is added into a beaker, 22.4g of sodium dodecyl benzene sulfonate is weighed and added into the beaker, the beaker is placed on a flat plate heater for heating, a glass rod is used for continuously stirring to enable the emulsifier to be completely dissolved, and a little KOH is added to adjust the pH value to be 14. The temperature of the solution is controlled to be 70 ℃, the emulsifier solution is slowly added into the glass kettle for premixing, the adding time is 5min, and the stirring rotating speed is controlled to be 2000rpm during the adding. After all the addition is completed, the stirring speed is increased to 8000rpm for emulsification, and the polyisoprene coarse latex is obtained after stirring for 20min at 55 ℃. The crude latex in the tank was desolventized and concentrated to give a stable polyisoprene latex at a concentration of 61 wt%.
Example 15
A polyisoprene latex was prepared as in example 9, except that instead of directly adding the nonionic emulsifier SPAN-80 to the n-hexane solvent, 0.75g of nonionic emulsifier SPAN-80 was also added at the same time as adding sodium dodecylbenzenesulfonate to deionized water.
Example 16
A polyisoprene latex was prepared as in example 10, except that the nonionic emulsifier Tween-61 was not directly added to the n-hexane solvent, but 1g of the nonionic emulsifier Tween-61 was also added at the same time when potassium disproportionated rosin acid was added to deionized water.
Example 17
A polyisoprene latex was prepared as in example 11, except that instead of directly adding the nonionic emulsifier SPAN-8 to the n-hexane solvent, 1.5g of nonionic emulsifier SPAN-8 was also added at the same time as adding potassium disproportionated rosin acid to deionized water.
Example 18
A polyisoprene latex was prepared as in example 12, except that the non-ionic emulsifier Tween-61 was not directly added to the n-hexane solvent, but 2g of non-ionic emulsifier Tween-61 was also added at the same time when sodium dodecylbenzenesulfonate was added to deionized water.
Test case
The latices prepared in examples 9 to 18 were tested for latex particle size, film tensile strength, molecular weight and latex placement stability, and the results are shown in Table 1.
TABLE 1
From the results, the polyisoprene latex prepared in examples 9-18 adopting the technical scheme of the invention has higher molecular weight, higher elongation at break of the adhesive film and tensile strength of the adhesive film, higher mechanical property, better film forming property and higher mechanical stability.
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 (10)
1. A method for removing an organic solvent from a crude polyisoprene latex, comprising: performing atmospheric distillation on the polyisoprene coarse latex without the solvent; then, the concentrated latex obtained by atmospheric distillation is subjected to optional reduced pressure distillation;
The method further comprises the steps of: during atmospheric distillation, inert gas is sprayed above the liquid level of the crude latex.
2. The method according to claim 1, wherein the amount of inactive gas sprayed per liter of raw latex is 0.1-10L, preferably 0.5-5L, most preferably 1-2L;
and/or the inactive gas is nitrogen, inert gas, air and CO 2 At least one of (a) and (b);
and/or the temperature of the inactive gas is from 0 ℃ to 50 ℃, preferably from 5 ℃ to 30 ℃, most preferably from 10 ℃ to 20 ℃;
and/or the pressure of the inactive gas spraying is 0.1MPa-1MPa, preferably 0.2MPa-0.8MPa, and most preferably 0.3MPa-0.6MPa;
and/or the inert gas is sprayed through a cylindrical tube with fine pores having a density of 50-2000 mesh, preferably 100-1000 mesh, most preferably 200-600 mesh.
3. A process according to claim 1, wherein the conditions of the atmospheric distillation are such that the solvent removed by the atmospheric distillation is 80% to 99% by volume, preferably 90% to 97% by volume, most preferably 93% to 96% by volume of the total amount of solvent in the crude latex;
and/or, the conditions of the reduced pressure distillation are such that the solvent removed by the reduced pressure distillation is from 1% to 20% by volume, preferably from 3% to 10% by volume, and most preferably from 4% to 7% by volume of the total amount of solvent in the crude latex.
4. A process according to claim 1, wherein the difference between the temperature of atmospheric distillation and the boiling point of the solvent in the crude latex is from 0 ℃ to 20 ℃, preferably from 3 ℃ to 15 ℃, most preferably from 5 ℃ to 8 ℃;
and/or the reduced pressure distillation is at a pressure of 0.05MPa to 0.0001MPa, preferably 0.01MPa to 0.001MPa, most preferably 0.008MPa to 0.003MPa;
and/or the difference between the temperature of the reduced pressure distillation and the boiling point of the solvent in the coarse latex is from 0 ℃ to 20 ℃, preferably from 2 ℃ to 15 ℃, most preferably from 3 ℃ to 10 ℃;
and/or the stirring speeds of the atmospheric distillation and the vacuum distillation are each independently 100rpm to 2000rpm, preferably 300rpm to 1600rpm, and most preferably 600rpm to 1200rpm.
5. A process according to claim 1, wherein the solvent content by volume in the crude latex is 30-70%, preferably 40-55%, most preferably 42-50%;
and/or the weight content of polyisoprene in the crude latex is 2% -10%, preferably 3% -8%, most preferably 4% -6%;
and/or the weight content of the emulsifier in the coarse latex is 0.5% -10%, preferably 1% -5%, most preferably 1.5% -4%.
6. The method according to claim 1, wherein the solvent in the crude latex is a saturated aliphatic hydrocarbon and/or an alicyclic hydrocarbon, preferably at least one of n-hexane, cyclohexane, methylcyclopentane, n-heptane, n-pentane and cyclopentane;
And/or the polyisoprene in the coarse latex has a number average molecular weight of 1 to 100 thousand g/mol, preferably 10 to 50 thousand g/mol, most preferably 20 to 35 thousand g/mol;
and/or the emulsifier in the crude latex is an anionic emulsifier and/or a nonionic emulsifier.
7. The method according to claim 1, wherein the atmospheric distillation is performed in an atmospheric distillation still and the reduced pressure distillation is performed in a reduced pressure distillation still, the atmospheric distillation still and the reduced pressure distillation still each being provided with a feed port, a solvent outlet and a discharge port, the discharge port of the atmospheric distillation still being connected to the feed port of the reduced pressure distillation still.
8. The process according to claim 7, wherein the volume ratio of the atmospheric to vacuum stills is 1-20, preferably 3-15, most preferably 5-8;
and/or the normal pressure distillation kettle and the reduced pressure distillation kettle are respectively provided with a heat exchange jacket, a heat exchange medium inlet of the heat exchange jacket is arranged at the bottom of the heat exchange jacket, and a heat exchange medium outlet is arranged at the top of the heat exchange jacket;
and/or, the feed inlet of the atmospheric distillation kettle is positioned at the bottom of the kettle body, the solvent outlet is positioned at the top of the kettle body, the discharge outlet is positioned at the middle upper part of the kettle body, and the ratio between the height of the discharge outlet and the height of the kettle body is 0.5-1, preferably 0.6-0.9, and most preferably 0.7-0.8.
9. The process according to claim 7, wherein the feed inlet of the reduced pressure distillation still is located at the bottom of the still body, the solvent outlet is located at the top of the still body, the discharge outlet is located at the middle upper part of the still body, and the ratio between the height of the discharge outlet and the height of the still body is 0.5-1, preferably 0.6-0.9, most preferably 0.7-0.8.
10. The method according to claim 7, wherein each of the atmospheric and vacuum stills is provided with a stirring unit comprising a stirring shaft and at least one stirring paddle vertically arranged and fixed on the stirring shaft, the number of stirring paddles being preferably 1-10, more preferably 2-8, most preferably 3-5.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116891543A (en) * | 2023-09-11 | 2023-10-17 | 新疆天利石化股份有限公司 | Method for preparing artificial latex by adopting parallel-serial continuous kettle type distillation method |
| CN116891543B (en) * | 2023-09-11 | 2023-12-19 | 新疆天利石化股份有限公司 | Method for preparing artificial latex by adopting parallel-serial continuous kettle type distillation method |
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