CN116023677A - Polyisoprene latex and preparation method thereof - Google Patents
Polyisoprene latex and preparation method thereof Download PDFInfo
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- CN116023677A CN116023677A CN202111243382.7A CN202111243382A CN116023677A CN 116023677 A CN116023677 A CN 116023677A CN 202111243382 A CN202111243382 A CN 202111243382A CN 116023677 A CN116023677 A CN 116023677A
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Abstract
The invention relates to the field of high polymer materials and preparation, and discloses polyisoprene latex and a preparation method thereof. The method comprises the following steps: (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 method can exert the emulsifying capacity of the emulsifying agent as much as possible, reduce the viscosity of the latex mixture and the loss of the molecular weight of rubber, and the polyisoprene latex prepared by the method has higher mechanical property, higher mechanical stability and better film forming property.
Description
Technical Field
The invention relates to the field of high polymer materials and preparation, in particular to polyisoprene latex and a preparation method thereof.
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.
There are many studies reported on polyisoprene latex at home and abroad. CN102936346a discloses a method for directly preparing isoprene latex by adopting a glue solution, wherein the emulsification of the polyisoprene glue solution is that the polyisoprene glue solution prepared in the first step is directly emulsified with an emulsifier aqueous solution by a high-speed shearing method. US2009/0281211A1 discloses a method for preparing an artificial latex, which adopts a rosin acid soap emulsifier to obtain a latex product by adopting a high-speed shearing method.
However, the existing reported preparation method of the artificial latex has obvious defects that the film forming property of the latex and the mechanical property of a latex product are affected due to large loss of mechanical molecular weight in the emulsification process of the latex, and the latex particles are not wrapped by the emulsifier sufficiently to be 'tight' so that the latex is unstable in the storage and transportation processes.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a polyisoprene latex and a preparation method thereof, wherein the method can exert the emulsifying capacity of an emulsifying agent as much as possible, reduce the viscosity of a latex mixture, reduce the molecular weight loss of rubber, and the polyisoprene latex prepared by the method has higher molecular weight, higher mechanical property, higher mechanical stability and better film forming property.
In order to achieve the above object, the first aspect of the present invention provides a method for preparing a polyisoprene latex, the method comprising:
(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.
In a second aspect, the invention provides a polyisoprene latex prepared by the method described above.
The method can exert the emulsifying capacity of the emulsifying agent as much as possible, reduce the viscosity of the latex mixture and reduce the molecular weight loss of rubber, and the polyisoprene latex prepared by the method has higher mechanical property, higher mechanical stability and better film forming property, and is suitable for the high-end medical industry.
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.
In the present invention, "tensile strength of a film" means tensile strength of rubber obtained after emulsion breaking of latex, and "elongation at break of a film" means elongation at break of rubber obtained after emulsion breaking of latex. If the polyisoprene latex has higher mechanical properties, the polyisoprene latex generally has better film forming property.
In a first aspect, the present invention provides a process for preparing a polyisoprene latex, the process comprising:
(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.
In a second aspect, the present invention provides a polyisoprene latex prepared by the method described above.
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.
According to a particularly preferred embodiment of the invention, the polyisoprene latex is prepared as follows:
pressing n-hexane solvent into the jacketed glass kettle, adding a nonionic emulsifier Tween-61 into the glass kettle to ensure that the mass concentration of the nonionic emulsifier in the nonionic emulsifier solution is 0.35-0.4%, and stirring until the nonionic emulsifier is completely dissolved; weighing polyisoprene dry adhesive with the number average molecular weight of 20-23 ten thousand g/mol, cutting into small blocks, adding into the glass kettle, wherein the dosage of the polyisoprene dry adhesive is 2.1-2.4% of the weight of the polyisoprene dry adhesive in the nonionic emulsifier solution, pre-emulsifying, the stirring speed of pre-emulsifying is 850-950rpm, and heating a jacket water bath of the glass kettle to ensure that the pre-emulsifying temperature is 45-55 ℃ and stirring for 5-7h;
adding deionized water into a beaker, weighing sodium dodecyl benzene sulfonate, adding the sodium dodecyl benzene sulfonate into the beaker, heating the beaker, continuously stirring the beaker by using a glass rod to completely dissolve an emulsifier, adding a little KOH to adjust the pH value to be 12.5-12.8, and preparing a dodecyl benzene sulfonic acid solution with the mass concentration of 3.6-4%; the temperature of the solution is controlled to be 55-60 ℃, the emulsifier solution is slowly added into the glass kettle for premixing, the adding time is 14-16min, and the stirring rotating speed is controlled to be 800-900rpm during the adding. After all the raw materials are added, the stirring speed is increased to 5500-6000rpm for emulsification, the mixture is stirred for 7-9min at 45-50 ℃ to obtain polyisoprene coarse latex, the coarse latex in the kettle is desolventized and then concentrated to obtain the polyisoprene latex with the concentration of 61-64 wt%.
The present invention will be described in detail by examples. 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 1
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 2
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 3
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 4
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 5
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 6
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%.
Comparative example 1
A polyisoprene latex was prepared as in example 1, 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.
Comparative example 2
A polyisoprene latex was prepared as in example 2, 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.
Comparative example 3
A polyisoprene latex was prepared as in example 3, 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.
Comparative example 4
A polyisoprene latex was prepared as in example 4, 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 1 to 6 and comparative examples 1 to 4 were tested for latex particle diameter, film tensile strength, molecular weight and latex placement stability, and the results are shown in Table 1.
TABLE 1
As can be seen from the results, the polyisoprene latex prepared in examples 1-6 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 of preparing a polyisoprene latex, comprising:
(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.
2. The method according to claim 1, wherein the mass amount of nonionic emulsifier in the nonionic emulsifier solution is 0.5-5%, preferably 0.8-3%, most preferably 1-2.5% of the mass of the polyisoprene dry gel;
and/or the mass of the anionic emulsifier is 5% -50%, preferably 8% -40%, more preferably 10% -30% of the mass of the polyisoprene dry adhesive.
3. The method according to claim 1, wherein the polyisoprene in the polyisoprene dry gel has a cis 1, 4-polyisoprene structure content of not less than 95 mass%, and the polyisoprene in the polyisoprene dry gel has a number average molecular weight of 15 to 40 ten thousand g/mol, preferably 18 to 30 ten thousand g/mol, and most preferably 20 to 23 ten thousand g/mol.
4. A method according to any one of claims 1-3, wherein the mass concentration of nonionic emulsifier in the nonionic emulsifier solution is 0.01-1%, preferably 0.12-0.5%, most preferably 0.15-0.4%;
and/or the nonionic emulsifier is 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 and/or polyoxyethylene sorbitan ether monostearate.
5. The method according to claim 1, wherein the solvent in the non-ionic emulsifier solution is selected from saturated aliphatic and/or alicyclic hydrocarbons, preferably at least one of n-hexane, cyclohexane, methylcyclopentane, n-heptane, n-pentane and cyclopentane.
6. The method according to claim 1, wherein the pre-emulsification temperature is from 10 ℃ to 80 ℃, preferably from 20 ℃ to 70 ℃, more preferably from 30 ℃ to 60 ℃;
the pre-emulsification time is 1h-24h, preferably 2h-15h, most preferably 3-10h;
the pre-emulsification is carried out under stirring at a rotational speed of 100rpm to 2000rpm, preferably 500rpm to 1500rpm, more preferably 700rpm to 1000rpm.
7. The method according to claim 1 or 6, wherein the anionic emulsifier is used in the form of an aqueous anionic emulsifier solution in which the mass concentration of anionic emulsifier is 0.1-10%, preferably 1.2-5%, most preferably 1.5-4%;
preferably, the aqueous anionic emulsifier has a pH of 9 to 15, more preferably 10 to 14, most preferably 11 to 13;
and/or the anionic emulsifier is at least one of a fatty acid salt of C12-C30, an alkylbenzene sulfonate of C12-C30 and an alkylsulfate salt of C12-C30, preferably at least one of sodium alkylbenzenesulfonate, oleate, laurate, abietate and linolenate, more preferably at least one of sodium dodecylbenzenesulfonate and potassium disproportionated abietate;
preferably, the premixing method comprises: adding an anionic emulsifier aqueous solution to the mixture, wherein the adding speed of the anionic emulsifier aqueous solution is 1-50% by volume/min, preferably 2-20% by volume/min, most preferably 3-10% by volume/min; the premixing is carried out under stirring conditions at a rotation speed of 100rpm to 3000rpm, preferably 300rpm to 2000rpm, most preferably 500rpm to 1000rpm; the temperature of the premixing is from 10 ℃ to 80 ℃, preferably from 20 ℃ to 70 ℃, more preferably from 30 ℃ to 60 ℃.
8. A method according to claim 1, wherein the emulsification is by mechanical emulsification with stirring at a speed of 1000rpm-10000rpm, preferably 2500rpm-8000rpm, most preferably 3500rpm-7000rpm;
and/or emulsifying for 2min-30min, preferably 5min-20min, most preferably 7min-15min;
and/or the temperature of emulsification is from 10 ℃ to 60 ℃, preferably from 20 ℃ to 55 ℃, more preferably from 30 ℃ to 50 ℃.
9. A polyisoprene latex prepared by the method of any one of claims 1-8.
10. The polyisoprene emulsion according to claim 9, wherein the number average molecular weight of the polyisoprene latex is 15 to 40 ten thousand g/mol, preferably 18 to 30 ten thousand g/mol, most preferably 20 to 23 ten thousand g/mol;
and/or the particle size of the polyisoprene latex is 100nm to 2000nm, preferably 200 to 1500nm, most preferably 300 to 1200nm;
and/or the polyisoprene latex has a tensile strength of 15MPa to 30MPa, preferably 18MPa to 25MPa, most preferably 20MPa to 22MPa;
and/or the polyisoprene latex has an elongation at break of 700% to 1500%, preferably 900% to 1300%, most preferably 1000% to 1200%;
and/or the polyisoprene latex has a concentration by mass of polyisoprene of 40 to 80% by mass, preferably 50 to 70% by mass, more preferably 55 to 65% by mass.
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