CN115260389B - Anionic crosslinked polymer and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of polymers, and discloses a preparation method of an anionic crosslinked polymer, which comprises the following steps: step 1: dispersing the monomer in an alcohol solvent, and adjusting the pH to be more than 5; step 2: adding a cross-linking agent, and heating under the protection of inert gas atmosphere; step 3: adding an initiator to initiate a reaction; step 4: separating and drying after the reaction is completed to obtain an anionic crosslinked polymer; the monomer consists of 2-acrylamide-2-methylpropanesulfonic acid and a nonionic monomer; the weight of the 2-acrylamide-2-methylpropanesulfonic acid is more than 90wt% of the weight of the monomer. The crosslinked polymer can be directly added into water for thickening without neutralization, the viscosity of a 1% aqueous solution of the crosslinked polymer can reach more than 50000 mPa.s, and the light transmittance of the crosslinked polymer can reach more than 86%, and the preparation method of the crosslinked polymer is also disclosed.

Description

Anionic crosslinked polymer and preparation method thereof

Technical Field

The invention relates to the field of polymers, in particular to an anionic crosslinked polymer and a preparation method thereof.

Background

In the field of polymeric thickeners, the most common are thickeners of natural origin and thickeners of chemical synthesis. Although natural thickeners have the advantages of degradability, they have the problems of unstable performance, insufficient product sources, unstable product supply, etc., so most of the thickeners used in various industries are chemically synthesized. Chemically synthesized thickeners can be classified into anionic thickeners, nonionic thickeners, and cationic thickeners, depending on the charge of the monomers used. The range of application of thickeners of different ionic types varies. Anionic thickeners are useful in anionic as well as nonionic systems, but are not suitable for use with cationic systems. Nonionic thickeners, while useful in both anionic, nonionic and cationic systems, have an incomparable thickening ability to ionic thickeners. Cationic thickeners, in contrast to anionic thickeners, can be used in cationic systems as well as nonionic systems. In the published patent and literature, anionic thickeners are mainly used.

The anionic powder thickeners which are relatively common in the market are mainly crosslinked polyacrylic acid, such as Lu Bo wetting company

A series. The components of the composition are mainly polyacrylic acid or a copolymer of acrylic acid and other monomers. Such polymers require the addition of an organic or inorganic base for neutralization to achieve the desired viscosity when used. Such polymers generally have a relatively good thickening ability under neutral or alkaline conditions and do not perform well in acidic environments.

The invention relates to an anionically crosslinked polymer with sulfonate groups. The polymer is neutralized before the reaction, so that no organic or inorganic base is added for neutralization. Since the polymer is a sulfonate type strong anionic group, a desired viscosity can be achieved in the pH range of 3-11. Such sulfonate-based crosslinked polymers have also found a place in the market in recent years as various gelling and thickening agents in cosmetic, dermatological and pharmaceutical compositions.

EP0816403 and WO98/00094 describe crosslinked homopolymers of 2-acrylamido-2-methylpropanesulfonates and their use as thickeners. EP0510246 describes in particular crosslinked copolymers of N-vinylformamide and of unsaturated alkylamides substituted by sulfonic acid groups, which are likewise suitable for thickeners.

US6355752B1 describes a crosslinked polymer consisting of 2-acrylamido-2-methylpropanesulfonate and nonionic acrylamide derivative monomers, the crosslinking agent being a polyfunctional allyl ether or polyfunctional (meth) acrylate. The polymer can be used as a thickener in the cosmetic or pharmaceutical fields.

Patent CN103492438B describes a water-soluble or water-swellable polymer. The polymer is copolymerized with a specific cross-linking agent of at least 3 polymerizable double bonds, which is 2-acrylamido-2-methylpropanesulfonic acid or salts thereof, which provides advantageous organoleptic properties and is particularly suitable as a thickener even in salt-containing compositions. It is also advantageously suitable for preparing cosmetic, dermatological or pharmaceutical compositions.

W02010/108634 discloses a crosslinked polymer comprising structural units derived from 2-acrylamido-2-methylpropanesulfonic acid or salts thereof and ethyl acrylate. The polymers are particularly suitable as thickeners and stabilizers in surfactant-containing compositions due to the formation of yield points.

CN201380066345.0 discloses a method for preparing comb copolymers, the backbone of which contains for 0 mole-%: -50-100 mole% of monomer units derived from 2-acrylamido-2-methylpropanesulfonic acid and up to 50 mole% of optional backbone monomer units, onto which a poly (N-alkylacrylamide) or poly (N, N-dialkylacrylamide) side segment is grafted, comprising the following successive steps: -step (a): bringing the formula (II): ch2=c (R2) -C (=o) -N (R3) (R4) compound with formula (IIIa): HS-R1-NH2 or of formula (IIIb): the limited chain compounds of HS-R1-C (=o) -OH react to give poly (N-alkylacrylamide) or poly (N, N-dialkylacrylamide) telomers of formula (Ia) or (Ib): H2N-R1-S- { CH2-C (R2) [ C (=o) N (R3) (R4) ] -N-H (Ia), or HO-C (=o) -R1-S- { CH2-C (R2) [ C (=o) N (R3) (R4) ] -N-H (Ib), wherein N is an integer greater than or equal to 2 and less than or equal to 100. -step (c): reacting a telomer of formula (Ia) or (Ib) with glycidyl methacrylate (IV) in t-butanol to give a solution of a macromer of formula (Va) or (Vb): ch2=c (R5) -C (=o) -NH-R1-Z- { CH2-C (R2) [ C (=o) N (R3) (R4) ] -N-H (Va); ch2=c (R5) -C (=o) -O- (c=o) -R1-Z- { CH2-C (R2) [ C (=o) N (R3) (R4) ] -N-H (Vb); -step (e): copolymerizing a macromer of formula (Va) or formula (Vb) in t-butanol with an ammonium salt of 2-acrylamido-2-methylpropanesulfonic acid and, if desired, one or more optional monomers in the desired molar ratio; also relates to novel comb copolymers.

The above-mentioned patent technology discloses the use of an anionic polymer related to 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof as a thickener, which, although having a good thickening ability, cannot satisfy both excellent thickening ability and transparency, limiting the range of use.

Disclosure of Invention

The invention aims to provide an anionic crosslinked polymer which can be directly added into water for thickening without neutralization, wherein the viscosity of a 1% aqueous solution of the anionic crosslinked polymer can reach more than 50000 mPas, and the light transmittance of the anionic crosslinked polymer can reach more than 86 percent.

In order to achieve the above purpose, the present invention provides the following technical solutions: a method for preparing an anionically crosslinked polymer comprising the steps of:

step 1: dispersing the monomer in an alcohol solvent, and adjusting the pH to be more than 5;

step 2: adding a cross-linking agent, and heating under the protection of inert gas atmosphere;

step 3: adding an initiator to initiate a reaction;

step 4: separating and drying after the reaction is completed to obtain an anionic crosslinked polymer;

the monomer consists of 2-acrylamide-2-methylpropanesulfonic acid and a nonionic monomer; the weight of the 2-acrylamide-2-methylpropanesulfonic acid is more than 90wt% of the weight of the monomer;

the dosage of the monomer is 10% -18% of the weight of the alcohol solvent;

the initiator is glycerol trimethylolpropane triacrylate, triethoxylated trimethylolpropane triacrylate, nonaethoxylated trimethylolpropane triacrylate, triethoxylated trimethylolpropane trimethacrylate or nonaethoxylated trimethylolpropane trimethacrylate;

the crosslinking agent is 2-3.5% of the monomer weight.

In the preparation method of the anionic crosslinked polymer, the dosage of the monomer is 12-14.5% of the weight of the alcohol solvent; the alcohol solvent is tertiary butanol.

In the preparation method of the anionic crosslinked polymer, the nonionic monomer is one or more of N-methyl methacrylamide, N-ethyl methacrylamide, N-propyl methacrylamide, N-isopropyl methacrylamide, N- (2-hydroxyethyl) methacrylamide, N-methoxy ethyl acrylamide, N-methoxy propyl acrylamide, N-dimethyl methacrylamide, N-diethyl methacrylamide, N-methyl acrylamide, N-ethyl acrylamide, N-propyl acrylamide, (N-isopropyl acrylamide, N- (2-hydroxyethyl) acrylamide, N-dimethyl acrylamide, N-diethyl acrylamide, vinyl pyrrolidone, hydroxyethyl acrylate and hydroxypropyl acrylate.

In the preparation method of the anionic crosslinked polymer, the nonionic monomer is a combination of at least two of N- (2-hydroxyethyl) methacrylamide, N-methoxymethacrylamide, N-methoxyethyl acrylamide, N-methoxypropyl acrylamide, N- (2-hydroxyethyl) acrylamide, vinylpyrrolidone, hydroxyethyl acrylate and hydroxypropyl acrylate.

In the preparation method of the anionic crosslinked polymer, the nonionic monomer is a combination of N-methoxy methacrylamide and hydroxyethyl acrylate or hydroxypropyl acrylate;

the ratio of the N-methoxymethacrylamide to the hydroxyethyl acrylate or the hydroxypropyl acrylate is 1:0.5-2.

In the preparation method of the anionic crosslinked polymer, the initiator is a peroxide initiator or an azo initiator; the initiator is equivalent to 0.02-1.5% of the weight of the monomer.

In the preparation method of the anionic crosslinked polymer, the initiator is one of di (2-ethylhexyl) peroxydicarbonate, dilauroyl peroxide, azobisisobutyronitrile and azobisisoheptonitrile.

In the preparation method of the anionic crosslinked polymer, the reaction temperature in the step 3 is 60-80 ℃; the reaction time of the step 3 is 4-8h.

Meanwhile, the invention also discloses an anionic crosslinked polymer, which is prepared by adopting any one of the methods.

Compared with the prior art, the invention has the beneficial effects that:

compared with similar commercial products, the anionic crosslinked polymer prepared by the invention has the advantages that the 1% hydrogel adhesiveness can reach more than 50000 mPa.s, and the 1% hydrogel transmittance can reach more than 86%.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Process for preparing polymers

40g of 2-acrylamido-2-methylpropanesulfonic Acid (AMPS), nonionic monomer and tert-butanol were introduced into a 500ml round-bottomed flask equipped with stirrer, thermometer, nitrogen inlet and reflux condenser, and the dispersion was carried out with stirring. And (3) introducing ammonia gas into the dispersion liquid to neutralize until the pH value of the dispersion liquid reaches 6-7, and stopping introducing the ammonia gas. Adding a cross-linking agent into the dispersion liquid, starting to introduce nitrogen, and starting to heat after introducing nitrogen for 30 min; the initiator is added after the temperature is raised to 65-75 ℃. After 5 hours of reaction, the reaction mixture was cooled to room temperature and filtered. And drying the filter cake to obtain polymer powder.

The related raw materials related to the invention are shown in the following table 1 for short:

TABLE 1

HEA	Hydroxy ethyl acrylate
		HEAA	N- (2-hydroxyethyl) acrylamide
NVP	Vinyl pyrrolidone
		AIBN	Azobisisobutyronitrile
ABVN	Azo diisoheptonitrile
		PO3-GPTA	Trihydroxypropyl glycerol ether triacrylate
TMPTA	Trimethylolpropane triacrylate
		EO3-TMPTA	Triethoxylation trimethylol propane triacrylate
EO9-TMPTA	Nonaethoxylated trimethylolpropane triacrylate
		EO3-TMPTMA	Triethoxylation trimethylol propane trimethacrylate
EO9-TMPTMA	Nine-ethoxylation trimethylol propane trimethyl acrylate

The relevant formulations for the examples of the invention are given in table 2 below (the weight units of the substances in table 2 are g):

TABLE 2

The examples and comparative examples described in Table 2 were each synthesized with reference to the preparation method of the polymer.

The light transmittance and viscosity test methods were as follows:

1% hydrogel viscosity test:

297g deionized water was weighed out and stirring was started. 3g of polymer powder is weighed and added into the weighed deionized water, after continuous stirring and dissolution are carried out for 15min, the obtained hydrogel is centrifugally defoamed, and then the viscosity of a sample is tested by adopting a BROOKFEIELD-RVT viscometer with the rotating speed of 20 rpm.

1% hydrogel viscosity test:

a1% hydrogel was also prepared and tested for light transmittance using an ultraviolet-visible spectrophotometer at a test wavelength of 420nm.

The results of the light transmittance and viscosity tests are shown in Table 3 below.

	viscosity/mPa.s	Transmittance/%
			Example 1	51000	94
Example 2	68000	89
			Example 3	63500	87
Example 4	71000	86
			Example 5	66000	91
Example 6	52600	92
			Example 7	63000	87
Example 8	51500	88
			Example 9	53000	95
Example 10	66500	94
			Example 11	69200	95
Example 12	54100	93
			Example 13	61000	90
Comparative example 1	45300	88
			Comparative example 2	57000	65
Comparative example 3	23300	72
			Comparative example 4	67000	83

From the above analysis of the results, it can be seen that:

PO3-GPTA, EO3 (9) -TMPTA, EO3 (9) -TMPTMA, which more easily achieved a balance of viscosity and light transmittance than TMPTA.

2. The neutralized AMPS, in combination with nonionic comonomers, can increase polymer viscosity while maintaining light transmittance at a high level in most cases.

3. Most nonionic comonomers have similar light transmittance and viscosity when used alone, and the characteristics of the nonionic comonomers are different in terms of viscosity and light transmittance according to the choice of monomer, but the nonionic comonomers are balanced.

4. Slightly higher reaction temperatures are helpful for the limited improvement of the thickening properties of certain comonomers with self-crosslinking functionality.

5. The compounding of the methoxyl-containing acrylamide and the hydroxyalkyl acrylate has certain advantages in the aspects of improving the viscosity and the light transmittance, the methoxyl-containing acrylamide and the hydroxyalkyl acrylate have certain self-crosslinking activity, the viscosity increase caused by the self-crosslinking activity is not obvious when the similar nonionic comonomer is singly used, when the two types of monomers with the self-crosslinking activity are compounded, the viscosity increase is relatively obvious, and meanwhile, the monomers have larger activity under the high temperature condition (more than 100 ℃), and the self-crosslinking activity is not strong in the reaction under the lower temperature, so that the self-crosslinking activity does not only have negative influence on the light transmittance, but also can improve the light transmittance by 2-4% under the proper synthesis condition.

Claims (2)

1. A process for preparing an anionically crosslinked polymer comprising the steps of:

step 1: dispersing the monomer in tertiary butanol, and adjusting the pH to be more than 5;

step 2: adding a cross-linking agent, and heating to 75 ℃ under the protection of inert gas atmosphere;

step 3: adding an initiator to initiate a reaction for 5 hours;

step 4: separating and drying after the reaction is completed to obtain an anionic crosslinked polymer;

the monomer consists of 2-acrylamide-2-methylpropanesulfonic acid and a nonionic monomer; the nonionic monomer is N-methoxymethylPropyleneAmide, hydroxyethyl acrylate;

the weight ratio of the tertiary butanol to the 2-acrylamide-2-methylpropanesulfonic acid to the N-methoxymethacrylamide to the hydroxyethyl acrylate is as follows: 333:38:1:1;

the cross-linking agent is nonaethoxylated trimethylolpropane triacrylate or nonaethoxylated trimethylolpropane trimethacrylate;

the weight ratio of the cross-linking agent to the 2-acrylamide-2-methylpropanesulfonic acid is 38:1.34;

the initiator is azodiisobutyronitrile;

the weight ratio of the initiator to the 2-acrylamide-2-methylpropanesulfonic acid is 38:0.15.

2. An anionically crosslinked polymer prepared by the process of claim 1.