阅读说明：本技术 一种两步正向悬浮聚合法制备的酚醛树脂微球及其制备方法 (Phenolic resin microsphere prepared by two-step forward suspension polymerization method and preparation method thereof ) 是由 王春红 鲍天舒 姜海涛 于 2021-08-17 设计创作，主要内容包括：本发明属于酚醛树脂材料领域,本发明公开了一种两步正向悬浮聚合法制备的酚醛树脂微球及其制备方法,该制备方法包括以下步骤：将交联用酚类、功能基化酚类、醛类、质子酸溶于短链酯类中,混合均匀,得到油相；然后将油相加热预聚直至快要有固体析出,得到预聚物；再将预聚物在水相中进行悬浮聚合,得到的产品再进行清洗,筛分,得到球形酚醛树脂。本发明提供的方法制备的酚醛树脂球形良好无粘连,粒径可控,强度很高,且在合格的粒径范围内成球率大于70％。(The invention belongs to the field of phenolic resin materials, and discloses a phenolic resin microsphere prepared by a two-step forward suspension polymerization method and a preparation method thereof, wherein the preparation method comprises the following steps: dissolving crosslinking phenols, functionalized phenols, aldehydes and protonic acid in short-chain esters, and uniformly mixing to obtain an oil phase; heating the oil phase for prepolymerization until solids are separated out soon to obtain a prepolymer; and carrying out suspension polymerization on the prepolymer in a water phase, and cleaning and screening the obtained product to obtain the spherical phenolic resin. The phenolic resin prepared by the method provided by the invention has the advantages of good sphericity, no adhesion, controllable particle size, high strength and a balling rate of more than 70% in a qualified particle size range.)

1. A method for preparing phenolic resin microspheres by a two-step forward suspension polymerization method is characterized by comprising the following steps:

dissolving crosslinking phenols, functionalized phenols, aldehydes and protonic acid in short-chain esters, and uniformly mixing to obtain an oil phase; heating the oil phase for prepolymerization until solids are separated out soon to obtain a prepolymer; and carrying out suspension polymerization on the prepolymer in a water phase, and cleaning and screening the obtained product to obtain the spherical phenolic resin.

2. The method for preparing phenolic resin microspheres by the two-step forward suspension polymerization method as claimed in claim 1, wherein the aqueous phase is sodium chloride aqueous solution, and the mass concentration of sodium chloride is 2-10%.

3. The method for preparing phenolic resin microspheres by the two-step forward suspension polymerization method according to claim 1, wherein in the oil phase, the molar ratio of the functionalized phenols to the crosslinking phenols is 0-1: 1, the molar ratio of the total phenols to the aldehydes is 3: 1-4, the mass ratio of the total phenols to the esters is 1: 2-3.5, and the use amount of the protonic acid is 10% -20% of the total mass of the reactants.

4. The method for preparing phenolic resin microspheres by the two-step forward suspension polymerization method according to claim 3, wherein the phenol for crosslinking is one of phenols having at least 3 reaction sites at the ortho-position of hydroxyl group, the functionalized phenol is one of phenols having two reaction sites at the ortho-position, the aldehyde is trioxane or paraformaldehyde, the protonic acid is hydrochloric acid or sulfuric acid, and the short-chain ester is ethyl acetate or butyl acetate.

5. The method for preparing phenolic resin microspheres by the two-step forward suspension polymerization method according to claim 1, wherein the prepolymerization temperature is 50-60 ℃, the electromagnetic stirring speed is 150-400 r/min, and the prepolymerization time is 4-40 min.

6. The method for preparing phenolic resin microspheres by the two-step forward suspension polymerization method according to claim 1, wherein the volume ratio of the oil phase to the water phase is 1:4, the suspension polymerization temperature is 60-80 ℃, the suspension polymerization stirring speed is 200-400 r/min, and the suspension polymerization time is 5-8 h.

7. The method for preparing phenolic resin microspheres by the two-step forward suspension polymerization method according to claim 1, wherein the cleaning is sequentially cleaning with pure water and ethanol, naturally drying, and then cleaning with petroleum ether.

8. The method for preparing phenolic resin microspheres according to claim 7, wherein the pure water washing end point is no protonic acid residue, the ethanol washing end point is no moisture residue, the natural drying time is 6-7 h, and the petroleum ether washing time is 5-8 h.

9. The method for preparing phenolic resin microspheres by the two-step forward suspension polymerization method as claimed in claim 1, wherein the particle size of the finally obtained microspheres is 100-500 μm.

10. The phenolic resin microspheres prepared by the method for preparing phenolic resin microspheres by the two-step forward suspension polymerization method as claimed in claims 1-9.

Technical Field

The invention relates to the field of resin materials, in particular to phenolic resin microspheres prepared by a two-step forward suspension polymerization method and a preparation method thereof.

Background

The phenolic resin is a resin used in bulk, and has the advantages of excellent mechanical property, high temperature resistance and acid and alkali resistance. The phenolic hydroxyl group introduced by the phenols as monomers has weak acidity, so that the phenols can become good weak acid resin, and different functional groups (such as catechol, salicylic acid and derivatives thereof) introduced by different phenols can make the phenols have wide application prospects in metal ion chelation, so that high requirements are provided for a phenolic resin balling process. The traditional ball grinding method has high cost, complex operation and poor final product spherical shape, can only be generally used for preparing spherical active carbon, and mostly adopts a suspension polymerization method when the spherical active carbon is used as the research and production of the adsorption resin.

However, in the prior art, the method for synthesizing spherical phenolic resin generally uses reversed phase suspension polymerization because aldehydes and phenols are reactants with strong polarity, and the used solvents are only water, alcohols and ethers, and are dispersed in the dispersed phase of liquid wax, dichloroethane and the like. The problems with this inverse suspension polymerization are mainly three: firstly, reactants are dissolved in a polar solvent with higher density, the bottom is very easy to sink in the reaction process, and a water-in-oil system has thermodynamic instability and is very difficult to disperse; secondly, micromolecular byproducts (such as water, methanol and the like) are generated in the phenolic aldehyde condensation process, if the micromolecular byproducts cannot be removed, the polymerization degree is difficult to improve, most micromolecular substances are dissolved in a polar solvent used in the reversed phase suspension polymerization, and the micromolecular substances are evaporated out at a higher reaction temperature in the synthesis process; thirdly, a large amount of organic solvent is used, which is not very environment-friendly.

The normal phase suspension polymerization is a more common and mature suspension polymerization method, an oil-in-water system is a thermodynamically stable system, the protection is easier, the density of a water phase is higher, the product is not easy to sink, and the adhesion after molding can be avoided at a lower stirring speed. Meanwhile, the method is more environment-friendly in mass production, is a more advantageous suspension polymerization method, but hinders the difficulty of synthesis control, and has no mature theoretical research and practical application so far.

Therefore, how to apply the more advantageous forward suspension polymerization method to the synthesis of spherical phenolic resin becomes a problem that needs to be solved urgently by those skilled in the art.

Disclosure of Invention

In view of the above, the present invention provides a phenolic resin microsphere prepared by a two-step forward suspension polymerization method and a preparation method thereof, wherein an aqueous solution is used to replace an organic solvent as a continuous phase, and a short-chain ester is used to replace a strong polar solvent. The yield of the prepared phenolic resin balls is more than 70%, the particle size can be controlled to be 100-500 mu m, and the balls are good and have no adhesion.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for preparing phenolic resin microspheres by a two-step forward suspension polymerization method, which specifically comprises the following steps:

s1, dissolving sodium chloride in water to obtain a water phase which is a dispersed phase of suspension polymerization;

s2, dissolving crosslinking phenols, functionalized phenols, aldehydes and protonic acid in short-chain esters to obtain an oil phase which is a suspension polymerization reaction phase, uniformly mixing the oil phase, performing electromagnetic stirring, and simultaneously heating for prepolymerization to obtain a prepolymer;

s3, adding the prepolymer obtained in the step S2 into the water phase obtained in the step S1 for suspension polymerization to obtain a crude product;

s4, washing the crude product obtained in the step S3 with pure water and ethanol in sequence, naturally drying the crude product, and then washing the crude product with petroleum ether to obtain spherical phenolic acid resin;

and S5, screening the spherical phenolic resin obtained in the step S4, and removing microspheres with unqualified particle sizes to obtain a final product.

Preferably, in the aqueous phase of step S1, the mass concentration of sodium chloride is 2% to 10%, more preferably, the mass concentration of sodium chloride is 2% to 5%;

preferably, in the oil phase of the step S2, the molar ratio of the functionalized phenols to the crosslinking phenols is 0-1: 1; the molar ratio of the total phenols to the aldehydes is 3: 1-4; the mass ratio of the total phenols to the esters is 1: 2-3.5; the dosage of the protonic acid is 10 to 20 percent of the total mass of the reactants, and the dosage of the protonic acid is more preferably 12 to 16 percent of the total mass of the reactants;

preferably, the crosslinking phenol is one of phenols having at least 3 reaction sites in the hydroxyl group ortho-para position, and is more preferably phenol or hydroquinone; the functionalized phenol is one of phenols with two reaction sites at ortho-para positions, and is more preferably one of catechol, salicylic acid and derivatives thereof; the aldehyde is trioxymethylene or paraformaldehyde; the protonic acid is hydrochloric acid or sulfuric acid, and hydrochloric acid is further preferable; the short-chain ester is ethyl acetate or butyl acetate, and ethyl acetate is further preferable;

preferably, in step S2, the prepolymerization temperature is 50-60 ℃, the electromagnetic stirring speed is 150-400 r/min, and the prepolymerization time is 4-40 min; further preferably, the prepolymerization temperature is 50-55 ℃, the electromagnetic stirring speed is 200-300 r/min, and the prepolymerization time is 10-40 min; further preferably, the prepolymerization temperature is 50 ℃, the electromagnetic stirring speed is 250r/min, and the prepolymerization time is 10-25 min;

preferably, in the step S3, the volume ratio of the oil phase to the water phase is 1:4, the suspension polymerization temperature is 60-80 ℃, the suspension polymerization stirring speed is 200-400 r/min, and the suspension polymerization time is 5-8 h; further preferably, the suspension polymerization temperature is 60-70 ℃, and the suspension polymerization time is 6-7 h; more preferably, the suspension polymerization time is 6 h;

preferably, in step S4, the pure water washing is finished by using aprotic acid residue, the ethanol washing is finished by using no water residue, the natural drying time is 6-7 h, and after drying, the soxhlet extractor is used for washing for 5-8 h by using petroleum ether; further preferably, the natural drying time is 6 hours, and the Soxhlet extractor is washed by petroleum ether for 6-7 hours; more preferably, the dried product is washed with petroleum ether in a Soxhlet extractor for 6 hours;

preferably, in step S5, microspheres having particle diameters of 100 to 500 μm are removed.

The invention also provides the phenolic resin microspheres prepared by the preparation method.

Preferably, the particle size of the phenolic resin microspheres prepared by the preparation method is 100-500 μm, and the water content is 51-65 wt%.

According to the technical scheme, compared with the prior art, the invention has the following beneficial effects:

in the invention, the homoionic effect of sodium chloride can reduce the dissolution of protonic acid in the water phase and can also adjust the density of the water phase; trioxymethylene and paraformaldehyde have different structural formulas, but the two aldehydes have consistent effects in synthesis.

According to the phenolic resin microspheres prepared by the method for preparing the phenolic resin microspheres by the two-step forward suspension polymerization method, different functionalized products do not need to change the process greatly, the prepared phenolic resin microspheres are non-adhesive spherical in appearance, the adjustable range of the particle size is 100-500 mu m, the water content is 51-65 wt%, and the balling rate after sieving is floated according to different phenols, but is all more than 70%.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Dissolving 5g of sodium chloride in 200mL of water, stirring in a 500mL three-neck flask, heating to 60 ℃ to obtain a water phase, weighing 13.44g of phenol, 6.31g of trioxymethylene and 50mL of ethyl acetate respectively, uniformly mixing, then dropwise adding 6mL of 37% concentrated hydrochloric acid to obtain an oil phase, heating in a water bath to 50 ℃ under the stirring of a magneton at 250r/min, and reacting for 15min to obtain a prepolymer. Adding the prepolymer into the water phase, adjusting the stirring speed to 200r/min to obtain sol with the particle size of about 500 mu m, and reacting for 6 hours at 60 ℃. Washing the obtained product with water until the pH value is unchanged, washing off excessive water with ethanol, naturally drying for 6 hours, performing soxhlet extraction for 6 hours with petroleum ether to obtain phenolic resin microspheres, and sieving with standard sieves of 450 and 550 mu m to obtain the final product.

The appearance characteristics and parameters of the phenolic resin microspheres obtained in this example are: the prepolymer is light pink liquid, the final product is milky non-adhesive spherical, the particle size is preferably 450-550 mu m, the water content is preferably 58.1 wt%, and the balling rate after sieving is 81%.

Example 2

Dissolving 15g of sodium chloride in 500mL of water, stirring in a 1L three-neck flask, heating to 70 ℃ to obtain a water phase, respectively weighing 16.76g of salicylic acid, 19.20g of phenol, 12.62g of trioxymethylene and 120mL of ethyl acetate, uniformly mixing, then dropwise adding 14mL of 37% concentrated hydrochloric acid to obtain an oil phase, heating in a water bath to 50 ℃ under the stirring of 250r/min magnetons, and reacting for 25min to obtain a prepolymer. Adding the prepolymer into the water phase, adjusting the stirring speed to 300r/min to obtain sol with the particle size of about 400 mu m, and reacting for 6 hours at 70 ℃. Washing the obtained product with water until the pH value is unchanged, washing off excessive water with ethanol, naturally drying for 6 hours, performing soxhlet extraction for 6 hours with petroleum ether to obtain phenolic resin microspheres, and sieving with 350-micrometer and 450-micrometer standard sieves to obtain the final product.

The appearance characteristics and parameters of the phenolic resin microspheres obtained in this example are: the prepolymer is light pink liquid, the final product is milky non-adhesive spherical, the particle size is preferably 350-450 mu m, the water content is preferably 53.6 wt%, and the balling rate after sieving is 72%.

Example 3

Dissolving 8g of sodium chloride in 200mL of water, stirring in a 500mL three-neck flask, heating to 60 ℃ to obtain a water phase, respectively weighing 10.01g of hydroquinone, 5.20g of catechol, 5.40g of trioxymethylene and 50mL of butyl acetate, uniformly mixing, then dropwise adding 6mL of 37% concentrated hydrochloric acid to obtain an oil phase, heating in a water bath to 50 ℃ under the stirring of 250r/min magnetons, and reacting for 4min to obtain a prepolymer. Adding the prepolymer into the water phase, adjusting the stirring speed to 300r/min to obtain sol with the particle size of about 200 mu m, and reacting for 6 hours at 60 ℃. Washing the obtained product with water until the pH value is unchanged, washing off excessive water with ethanol, naturally drying for 6 hours, performing soxhlet extraction for 6 hours with petroleum ether to obtain phenolic resin microspheres, and sieving with standard sieves of 150 micrometers and 250 micrometers to obtain the final product.

The appearance characteristics and parameters of the phenolic resin microspheres obtained in this example are: the prepolymer is light green liquid, the final product is black non-adhesive spherical, the particle size is preferably 150-250 mu m, the water content is preferably 56.9 wt%, and the balling rate after sieving is 88%.

Example 4

Dissolving 10g of sodium chloride in 250mL of water, stirring in a 500mL three-neck flask, heating to 60 ℃ to obtain a water phase, respectively weighing 8.37g of hydroquinone, 8.34g of salicylic acid, 6.31g of trioxymethylene and 60mL of butyl acetate, uniformly mixing, then dropwise adding 7mL of 37% concentrated hydrochloric acid to obtain an oil phase, heating in a water bath to 50 ℃ under the stirring of 250r/min magnetons, and reacting for 8min to obtain a prepolymer. Adding the prepolymer into the water phase, adjusting the stirring speed to 200r/min to obtain sol with the particle size of about 400 mu m, and reacting for 6 hours at 60 ℃. Washing the obtained product with water until the pH value is unchanged, washing off excessive water with ethanol, naturally drying for 6 hours, performing soxhlet extraction for 6 hours with petroleum ether to obtain phenolic resin microspheres, and sieving with 350-micrometer and 450-micrometer standard sieves to obtain the final product.

The appearance characteristics and parameters of the phenolic resin microspheres obtained in this example are: the prepolymer is light green liquid, the final product is black non-adhesion spherical, the particle size is preferably 350-450 mu m, the water content is preferably 57.5 wt%, and the balling rate after sieving is 75%.

Example 5

Dissolving 5g of sodium chloride in 200mL of water, stirring in a 500mL three-neck flask, heating to 60 ℃ to obtain a water phase, weighing 13.44g of phenol, 6.31g of trioxymethylene and 50mL of ethyl acetate respectively, uniformly mixing, then dropwise adding 3mL of 70% dilute sulfuric acid to obtain an oil phase, heating in a water bath to 50 ℃ under the stirring of a magnetic particle at the speed of 250r/min, and reacting for 15min to obtain a prepolymer. Adding the prepolymer into the water phase, adjusting the stirring speed to 200r/min to obtain sol with the particle size of about 500 mu m, and reacting for 6 hours at 60 ℃. Washing the obtained product with water until the pH value is unchanged, washing off excessive water with ethanol, naturally drying for 6 hours, performing soxhlet extraction for 6 hours with petroleum ether to obtain phenolic resin microspheres, and sieving with standard sieves of 450 and 550 mu m to obtain the final product.

The appearance characteristics and parameters of the phenolic resin microspheres obtained in this example are: the prepolymer is light pink liquid, the final product is milky non-adhesive spherical, the particle size is preferably 450-550 mu m, the water content is preferably 55.4 wt%, and the balling rate after sieving is 76%.

Comparative example 1

Dissolving 8g of sodium chloride in 300mL of water, stirring in a 500mL three-neck flask, heating to 60 ℃ to obtain a water phase, respectively weighing 5.01g of hydroquinone, 12.56g of salicylic acid, 5.41g of trioxymethylene and 50mL of ethyl acetate, uniformly mixing, then dropwise adding 7mL of 37% concentrated hydrochloric acid to obtain an oil phase, heating in a water bath to 50 ℃ under the stirring of a magneton at a speed of 250r/min, and reacting for 10min to obtain a prepolymer. Adding the prepolymer into the water phase, adjusting the stirring speed to 300r/min to obtain sol with the particle size of about 200 mu m, and reacting for 6 hours at 60 ℃. Washing the obtained product with water until the pH value is unchanged, washing off excessive water with ethanol, naturally drying for 6 hours, performing soxhlet extraction for 6 hours with petroleum ether to obtain phenolic resin microspheres, and sieving with standard sieves of 150 micrometers and 250 micrometers to obtain the final product.

The appearance characteristics and parameters of the phenolic resin microspheres obtained in the comparative example are as follows: the prepolymer is light green liquid, the final product is black non-adhesive spherical, the particle size is preferably 150-250 mu m, the water content is preferably 60.3 wt%, and the balling rate after sieving is 48%.

In this comparative example, since the molar ratio of the functionalized phenol to the crosslinking phenol used exceeds the above-mentioned preferable range, most of the functionalized phenol is not reacted on the resin skeleton, and thus the degree of balling is low.

Comparative example 2

Dissolving 9g of sodium chloride in 300mL of water, stirring in a 500mL three-neck flask, heating to 60 ℃ to obtain a water phase, weighing 13.44g of phenol, 6.31g of trioxymethylene and 60mL of ethyl acetate respectively, uniformly mixing, then dropwise adding 7mL of 37% concentrated hydrochloric acid to obtain an oil phase, heating in a water bath to 50 ℃ under the stirring of a magneton at 250r/min, and reacting for 25min to obtain a prepolymer. Adding the prepolymer into the water phase, adjusting the stirring speed to 400r/min, so that a spherical sol cannot be obtained, stirring the whole oil phase into a belt-shaped oligomer, and reacting for 6 hours at 70 ℃. Only a viscous solid of poor strength is obtained.

This comparative example failed because the amount of esters exceeded the preferences, and the reaction rate was too slow after dispersion to cure rapidly into spheres.

As can be seen from the above examples and comparative examples, the phenolic resin microspheres synthesized by the method provided by the invention have good sphericity, no adhesion, controllable particle size, high strength and a balling rate of more than 70% after sieving.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.