CN115536773A

CN115536773A - Production method of high-temperature-resistant sodium polyacrylate

Info

Publication number: CN115536773A
Application number: CN202211358902.3A
Authority: CN
Inventors: 张文会
Original assignee: Jiangsu Pac & Cmc Manufacturing Co ltd
Current assignee: Jiangsu Pac & Cmc Manufacturing Co ltd
Priority date: 2022-11-01
Filing date: 2022-11-01
Publication date: 2022-12-30
Anticipated expiration: 2042-11-01
Also published as: CN115536773B

Abstract

The invention provides a method for producing high-temperature-resistant sodium polyacrylate. In order to solve the problem that the traditional sodium polyacrylate water-absorbing resin adopts an N, N' -methylene bisacryloyl cross-linking agent which does not resist high temperature, the invention adopts the combination of diethylene glycol diallyl ether and pentaerythritol diallyl ether as the cross-linking agent, produces the sodium polyacrylate by a solution polymerization method, and improves the high-temperature resistance performance under the condition of ensuring high liquid absorption rate, thereby obtaining the sodium polyacrylate with high liquid absorption rate at normal temperature and high temperature. The production method has simple process, is easy for large-scale application, and is an economical and efficient production method of the high-temperature-resistant sodium polyacrylate.

Description

Production method of high-temperature-resistant sodium polyacrylate

Technical Field

The invention relates to the field of chemical industry, in particular to a production method of high-temperature-resistant sodium polyacrylate.

Background

Sodium polyacrylate (Sodium polyacrylate), abbreviated as PAAS or PAA-Na, is a water-soluble high molecular compound, the relative molecular mass is as small as hundreds and as large as tens of millions, the Sodium polyacrylate is colorless dilute solution to transparent elastic colloid or even solid along with the increase of the relative molecular mass, and the property and the application are obviously different along with the difference of the relative molecular mass. The sodium polyacrylate can be used as dispersant, and can be used in water treatment, papermaking, textile printing and dyeing, ceramics and other industrial fields. The important application of the sodium polyacrylate is as a high water absorption resin, and the sodium polyacrylate is applied to various aspects such as sanitary products, agriculture, industry, construction, medicine, food, light industry and the like.

As the super absorbent resin, it must have three conditions: (1) The resin contains a large number of hydrophilic groups, and the hydrophilic groups can increase the adsorption force of the resin on water; (2) The water absorption capacity is influenced by the high or low crosslinking density due to the proper crosslinking degree; (3) Has a proper three-dimensional network structure, so that water molecules can drill into the network. Most of the existing sodium polyacrylate water-absorbing resins are synthesized by taking N, N' -methylene bisacrylamide as a cross-linking agent, but have the defects of easy hydrolysis, poor high-temperature resistance and easy water solubility at high temperature, and the application of sodium polyacrylate in the high-temperature field is limited.

Therefore, it is of great significance to develop a sodium polyacrylate with high water absorption capacity and high temperature resistance.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a production method of high-temperature-resistant sodium polyacrylate.

The production method of the invention comprises the following steps:

diluting a certain amount of monomer acrylic acid with a proper amount of water, neutralizing the monomer acrylic acid with a sodium hydroxide solution at 0-5 ℃ to a certain neutralization degree, and sequentially adding an initiator and a cross-linking agent 1 under stirring in an inert gas atmosphere: diethylene glycol diallyl ether and crosslinking agent 2: pentaerythritol diallyl ether forms reaction liquid, the content of monomer acrylic acid in the reaction liquid is 35-45%, the neutralization degree is 70-80%, the content of an initiator is 0.4-0.6%, the content of a cross-linking agent 1 is 0.03-0.08%, and the content of a cross-linking agent 2 is 0.05-0.2%; stirring uniformly, reacting for 5-30 min at 50-80 ℃, standing until a rubber-like elastic body appears, drying, crushing and sieving to obtain the sodium polyacrylate.

In one embodiment, the concentration of sodium hydroxide in the sodium hydroxide solution is between 20 and 35%, preferably 30%.

In one embodiment, the monomeric acrylic acid is present in an amount of 38 to 42% by mass, preferably 40% by mass. When the concentration of acrylic acid is too low, the polymerization reaction rate is slow, the resin conversion rate is low, the liquid absorption rate is low, and the high temperature resistance is deteriorated. When the concentration of acrylic acid is too high, neutralized sodium acrylate may precipitate out in solution, and the solubility of the initiator and the crosslinking agent becomes low, resulting in a decrease in the molecular weight of the resin, a decrease in the liquid absorption rate, and a deterioration in the high-temperature resistance to some extent.

In one embodiment, the degree of neutralization is from 73 to 77%, preferably 75%. When the neutralization degree is too low, the dissociation degree of carboxyl in the sodium polyacrylate network is small, molecular chains and the network are in a shrinkage state, and the liquid absorption rate is small; when the neutralization degree is too high, the polymerization rate is reduced, the concentration of sodium carboxyl in the sodium polyacrylate is too high, the water solubility of the sodium polyacrylate is increased, the network is reduced, the liquid absorption rate is reduced, and the high-temperature resistance is reduced.

In one embodiment, the initiator may be at least one of an azo-type initiator, a peroxide initiator, and a redox-type initiator. Preferably, the azo-type initiator includes water-soluble azobisisobutyramidine hydrochloride (AIBA), azobisisobutyrimidazoline hydrochloride (AIBI); the peroxide initiator comprises hydrogen peroxide, potassium persulfate and ammonium persulfate; the redox initiator comprises potassium persulfate/sodium bisulfite, ammonium persulfate/sodium bisulfite, hydrogen peroxide/ferrous sulfate, hydrogen peroxide/ferrous chloride, potassium persulfate/ferrous chloride, and potassium persulfate/ethylenediamine. The content of the initiator is 0.45 to 0.55%, preferably 0.5%. When the content of the initiator is too low, the chain initiation efficiency is insufficient, the crosslinking is incomplete, the molecular weight of the sodium polyacrylate is low, and the liquid absorption rate is low; when the content of the initiator is too high, implosion is easily caused to cause incomplete polymerization, and the liquid absorption rate is also low.

In one embodiment, the crosslinker 1 is present in an amount of 0.03 to 0.06%, preferably 0.06%; the content of the crosslinking agent 2 is 0.05 to 0.15%, preferably 0.15%. When the total amount of the cross-linking agent is too low, the cross-linking degree of the sodium polyacrylate is small, the network space is too large, the soluble part is more, the liquid absorption rate is low, and the high-temperature resistance is insufficient; when the total amount of the crosslinking agent is too large, the crosslinking degree is large, so that the network space is reduced, the amount of liquid which can be contained is also reduced, and the liquid absorption rate is reduced. The combination of the cross-linking agent 1 and the cross-linking agent 2 is used, the sodium polyacrylate has high liquid absorption rate and enhanced high-temperature resistance, and particularly, when the ratio of the cross-linking agent 1 to the cross-linking agent 2 is 1.5-3.0, preferably 2.0-2.5, the sodium polyacrylate has the best liquid absorption rate and high-temperature resistance.

In one embodiment, the temperature during the reaction is between 65 and 70 ℃. When the reaction temperature is too low, the polymerization reaction and the crosslinking reaction are faster, the crosslinking network structure is less, the liquid absorption rate is reduced, and the high-temperature resistance is deteriorated; when the reaction temperature is too high, more chain transfer occurs to cause the relative molecular mass of the product to be reduced, the soluble part of the sodium polyacrylate is increased, the liquid absorption rate is poor and the high temperature resistance is insufficient.

In the present invention, the parts, multiples and contents are based on mass unless otherwise specified.

In the present invention, the inert gas includes nitrogen and argon.

In another aspect of the present invention, the present invention also provides sodium polyacrylate produced according to the production method of the present invention.

The invention also provides application of the sodium polyacrylate as water-absorbent resin.

Advantageous effects

The invention provides a method for producing high-temperature-resistant sodium polyacrylate and sodium polyacrylate produced by the method. The invention adopts the combination of diethylene glycol diallyl ether and pentaerythritol diallyl ether as the cross-linking agent, and compared with the conventionally used N, N' -methylene diacryloyl cross-linking agent, the high-temperature resistance of the sodium polyacrylate is improved under the condition of ensuring the high liquid absorption rate of the sodium polyacrylate, so that the sodium polyacrylate with the high liquid absorption rate at both normal temperature and high temperature is obtained. The production method has simple process, is easy for large-scale application, and is an economical and efficient production method of the high-temperature resistant sodium polyacrylate.

Detailed Description

The following will clearly and completely describe the technical solutions of the embodiments of the present invention, 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 obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

The experimental procedures in the following examples are conventional unless otherwise specified. The examples do not show the specific techniques or conditions, according to the technical or conditions described in the literature in the field, or according to the product specifications.

The production method of the sodium polyacrylate comprises the following steps:

diluting a certain amount of acrylic acid with a proper amount of water, neutralizing the acrylic acid with a 30wt% sodium hydroxide solution in an ice water bath to a certain neutralization degree, introducing nitrogen for 30min, sequentially adding a certain amount of an initiator (potassium persulfate), a crosslinking agent 1 (diethylene glycol diallyl ether) and a crosslinking agent 2 (pentaerythritol diallyl ether) into the acrylic acid under magnetic stirring, uniformly stirring, placing the acrylic acid and the crosslinking agent at a certain temperature, stirring for 10min, standing until a rubber-like elastomer appears, drying, crushing and sieving the acrylic acid and the crosslinking agent in a 110 ℃ oven to obtain a sodium polyacrylate product.

The resulting sodium polyacrylate was tested for liquid absorption capacity according to the following method:

accurately weighing 0.3g of sample, putting the sample into a 1000mL beaker, adding sufficient deionized water, swelling for 12h at different temperatures, cooling to room temperature, leaching for 5min by using a 100-mesh nylon bag, weighing the mass of the gel after water absorption, and calculating the water absorption by the following formula:

Q＝(m–m ₀ )/m ₀

in the formula: q represents the liquid absorption rate of the sodium polyacrylate, and the unit is g/g; m represents the mass of the gel after water absorption and has a unit of g; m is a unit of ₀ Represents the mass of the dried sample in g.

In the same way, physiological saline is used to replace deionized water, and the saline absorption rate is obtained.

Example 1:

the fixed neutralization degree was 75%, the concentration of the crosslinking agent 1 was 0.06%, the concentration of the crosslinking agent 2 was 0.15%, the concentration of the initiator was 0.5%, the reaction temperature was 70 ℃, and the results are shown in table 1 below, with varying monomer concentrations.

Table 1:

monomer concentration	Water absorption rate at 25 DEG C	Water absorption rate at 180 DEG C
			30％	1340	1154
35％	1685	1569
			40％	2374	2357
45％	1765	1760
			50％	1162	1122

Example 2:

the fixing monomer concentration was 40%, the crosslinking agent 1 concentration was 0.06%, the crosslinking agent 2 concentration was 0.15%, the initiator concentration was 0.5%, the reaction temperature was 70 ℃, and the results are shown in table 2 below, with varying degrees of neutralization.

Table 2:

degree of neutralization	Water absorption rate at 25 DEG C	Water absorption rate at 180 DEG C
			65％	1088	854
70％	1785	1705
			75％	2367	2349
80％	1684	1597
			85％	1454	987

Example 3:

the fixed monomer concentration was 40%, the neutralization degree was 75%, the initiator concentration was 0.5%, the reaction temperature was 70 ℃, and the crosslinker concentration was varied, the results being shown in table 3 below.

Table 3:

cross-linker 1 concentration	Cross-linker 2 concentration	Water absorption rate at 25 DEG C	Water absorption rate at 180 DEG C
				-	0.21％	2036	1934
0.21％	-	1345	1338
				0.03％	0.05％	1537	1439
0.05％	0.03％	1214	1172
				0.06％	0.15％	2386	2371
0.15％	0.06％	1814	1804
				0.08％	0.20％	1876	1863

Example 4:

the fixing monomer concentration was 40%, the neutralization degree was 75%, the crosslinking agent 1 concentration was 0.06%, the crosslinking agent 2 concentration was 0.15%, the reaction temperature was 70 ℃, and the initiator concentration was varied, with the results shown in table 4 below.

Table 4:

initiator concentration	Water absorption rate at 25 DEG C	Water absorption rate at 180 DEG C
			0.30％	845	675
0.40％	1637	1528
			0.50％	2373	2356
0.55％	2140	2146
			0.60％	1739	1726

Example 5:

the reaction temperature was varied with a fixing monomer concentration of 40%, a neutralization degree of 75%, a crosslinking agent 1 concentration of 0.06%, a crosslinking agent 2 concentration of 0.15%, and an initiator concentration of 0.5%, and the results are shown in table 5 below.

Table 5:

reaction temperature	Water absorption rate at 25 DEG C	Water absorption rate at 180 DEG C
			40℃	651	325
50℃	1618	1592
			70℃	2384	2370
80℃	1932	1768

Example 6:

the fixed monomer concentration was 40%, the neutralization degree was 75%, the crosslinking agent 1 concentration was 0.06%, the crosslinking agent 2 concentration was 0.15%, the initiator concentration was 0.5%, the reaction temperature was 70 ℃, and the test conditions were changed, and the results are shown in table 6 below.

Table 6:

	25℃	60℃	120℃	180℃	240℃	300℃
							water absorption rate	2378	2382	2374	2365	2357	2340
Saline absorption rate	245	242	238	233	227	220

Comparative example 1:

the method of example 1 was used, wherein the crosslinker was replaced by 0.21% of N, N' -methylenebisacrylamide, the monomer concentration was 40%, the degree of neutralization was 75%, the initiator concentration was 0.5%, and the reaction temperature was 70 ℃. The water absorption and the salt water absorption of the resulting sodium polyacrylate at 25 ℃ and 180 ℃ were measured, and the results are shown in Table 7 below.

Table 7:

	25℃	180℃
			water absorption rate	2398	1452
Water absorption rate of salt	263	155

The foregoing describes preferred embodiments of the present invention, but is not intended to limit the invention thereto. Those skilled in the art may make modifications and variations to the embodiments disclosed herein without departing from the scope and spirit of the invention.

Claims

1. A method for producing high-temperature-resistant sodium polyacrylate comprises the following steps:

diluting a certain amount of monomer acrylic acid by using a proper amount of water, neutralizing the monomer acrylic acid by using a sodium hydroxide solution at the temperature of between 0 and 5 ℃ to a certain neutralization degree, and sequentially adding an initiator and a cross-linking agent 1: diethylene glycol diallyl ether and crosslinking agent 2: pentaerythritol diallyl ether forms reaction liquid, the content of monomer acrylic acid in the reaction liquid is 35-45%, the neutralization degree is 70-80%, the content of an initiator is 0.4-0.6%, the content of a cross-linking agent 1 is 0.03-0.08%, and the content of a cross-linking agent 2 is 0.05-0.2%; stirring uniformly, reacting for 5-30 min at 50-80 ℃, standing until rubber-like elastic bodies appear, drying, crushing and sieving to obtain the sodium polyacrylate.

2. The production method according to claim 1, wherein the concentration of sodium hydroxide in the sodium hydroxide solution is 20 to 35%.

3. The production process according to claim 1, wherein the monomer acrylic acid is contained in an amount of 38 to 42% by mass, preferably 40% by mass.

4. The production process according to claim 1, characterized in that the degree of neutralization is 73 to 77%, preferably 75%.

5. The production method according to claim 1, wherein the initiator is at least one of an azo-type initiator, a peroxide initiator, and a redox-type initiator.

6. The production method according to claim 1, wherein the azo-type initiator includes water-soluble azobisisobutyramidine hydrochloride (AIBA), azobisisobutyrimidazoline hydrochloride (AIBI); the peroxide initiator comprises hydrogen peroxide, potassium persulfate and ammonium persulfate; the redox initiator comprises potassium persulfate/sodium bisulfite, ammonium persulfate/sodium bisulfite, hydrogen peroxide/ferrous sulfate, hydrogen peroxide/ferrous chloride, potassium persulfate/ferrous chloride, and potassium persulfate/ethylenediamine.

7. The production method according to claim 1, wherein the content of the initiator is 0.45 to 0.55%.

8. The production method according to claim 1, wherein the content of the crosslinking agent 1 is 0.06 to 0.08%, the content of the crosslinking agent 2 is 0.15 to 0.20%, and the ratio of the crosslinking agent 1 to the crosslinking agent 2 is 1.5 to 3.0.

9. The production method according to claim 1, wherein the temperature at the time of the reaction is 65 to 70 ℃.

10. A sodium polyacrylate produced by the production method according to any one of claims 1 to 9.