JPH0678396B2 - Method for producing water-soluble acrylic copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing a water-soluble acrylic copolymer, specifically, various materials used for a paste, a latex, a raw material for ceramics molding, cosmetics, pharmaceuticals and the like. As a thickener for aqueous solutions,
Also, sanitary products, water retention materials for agricultural and horticultural use, or wall materials for breathing water that absorbs indoor moisture when the humidity is high and expels the absorbed moisture when the room is dry, fire during a fire. The present invention relates to a method for producing a water-soluble acrylic copolymer used as a water-absorbing agent or a water-retaining agent, which is useful for preventing the diffusion of the above.

[Conventional technology]

Among the homopolymers of acrylic acid and methacrylic acid and their salts, particularly high-polymerization products or high-molecular compounds obtained by crosslinking them are highly repellent in water due to repulsion by high-density anions. For the purpose of showing, these polymers are widely used as thickeners or water-absorbing polymers by utilizing such properties.

However, this polymer has a drawback that when it encounters an counterion, it loses electrical repulsion and causes an extreme decrease in viscosity.

That is, for example, a salt of polyacrylic acid such as sodium polyacrylate, a salt of polymethacrylic acid such as sodium polymethacrylate, etc. can be an excellent thickener by being dissolved in water, but sensitivity to a specific electrolyte And has a tendency to drastically reduce its viscosity when it comes into contact with an electrolyte such as sodium chloride in water solubility.

The sodium ion (cation) in the electrolyte such as sodium chloride is opposed to the carboxyl anion (anion) of sodium polyacrylate, and the presence of this counterion causes the ion to be electrically neutralized and repelled. It is presumed that the above-mentioned decrease in viscosity occurs, and thus the above-mentioned decrease in viscosity occurs.

As a method of solving this problem, US Pat.
No. 4,509,949 proposes copolymerizing an ester of acrylic acid or methacrylic acid having an alkyl group having 10 to 30 carbon atoms.

[Problems to be solved by the invention]

However, the higher fatty acid ester copolymer in the above-mentioned US patent has a drawback that it takes a long time to dissolve the powder product in water, and when the content of the copolymer increases, a transparent liquid is not obtained. Since it has a property of becoming a milky white liquid, its use is naturally limited.

In view of such a current situation, an object of the present invention is to prepare a water-soluble copolymer by combining at least two different kinds of copolymerization components, thereby increasing the aqueous solution which is colorless and transparent and has excellent salt resistance. It is intended to provide a method for producing an acrylic copolymer that can be used as a salt agent, a water absorbing agent, a water retaining agent, and the like.

[Means for solving problems]

In order to achieve the above object, the method for producing a water-soluble acrylic copolymer of the present invention is characterized by copolymerizing at least the compounds shown in the following (a) and (b).

A method for producing a water-soluble acrylic copolymer, which comprises copolymerizing at least the compounds shown in the following (a) and (b).

(A) 90.0 to 98.5% by weight of acrylic acid and / or methacrylic acid (b) 10.0 to 1.5% by weight of higher fatty acid ester or higher aliphatic alkyl ether of polyhedral alcohol having at least 3 carbons and 3 hydroxyl groups And an ester or allyl ether compound of acrylic acid or methacrylic acid of a compound having at least one hydroxyl group at the terminal,
Alternatively, a higher fatty acid ester of a polyhydric alcohol having at least 3 carbons and 3 hydroxyl groups or a higher aliphatic alkyl ether to which ethylene oxide or / and propylene oxide is added, and at least 1 hydroxyl group is added to the terminal. Acrylic acid or methacrylic acid ester or allyl ether compound of the compound having the main component of the compound used in the method for producing the water-soluble acrylic copolymer of the present invention is acrylic acid represented by the compound (a) or / and Methacrylic acid, the compound (b)
90.0-98.5% as a blending ratio with (% by weight; the same applies below)
Used in the range of.

If the amount is less than 90.0%, the original performance as a thickener or water absorbing agent, or a water retention agent decreases,
If it exceeds 98.5%, the compounding amount of the compound (b) that substantially exhibits a salt resistance function decreases, and as a result, the salt resistance of the copolymer decreases and it is not possible to obtain a copolymer having desired performance.

Such a compound (a) has at least a part of its carboxyl group, for example, sodium hydroxide, potassium hydroxide,
It may be a neutralizing monomer neutralized with a neutralizing agent such as an alkali metal hydroxide such as lithium hydroxide or ammonia, or a volatile amine such as triethylamine or triethanolamine.

The higher fatty acid of polyhydric alcohol having at least 3 carbons and 3 hydroxyl groups in the compound (b) shown as one of the copolymerization components for acrylic acid and / or methacrylic acid in (a) above. Esters or higher aliphatic alkyl ethers with at least 1 at the end
Acrylic acid or methacrylic acid ester of a compound having one hydroxyl group or an allyl ether compound [hereinafter referred to as compound (i)] is a condensate of a compound having a polyhydric alcohol structure such as sorbit, for example, Sorbitan with lauric acid, palmitic acid, stearic acid, higher fatty acids such as oleic acid or lauryl alcohol,
It reacts with higher aliphatic alcohols such as palmityl alcohol, stearyl alcohol, and euler alcohol to condense and dehydrate a portion of the OH groups, which are hydrophilic groups in the polyhydric alcohol structure, to make it lipophilic, and other OH groups. An acrylic acid group or a methacrylic acid group is introduced into the portion to cause esterification, or an allyl group is introduced to form an ether bond.

On the other hand, higher fatty acid ester of polyhydric alcohol having at least 3 carbons and 3 hydroxyl groups, or a compound obtained by adding ethylene oxide and / or propylene oxide to higher aliphatic alkyl ether and having at least 1 hydroxyl group at the terminal The acrylic acid or methacrylic acid ester or allyl ether compound (hereinafter referred to as compound (ii)) is a higher fatty acid ester of the polyhydric alcohol obtained above, or a higher aliphatic alkyl ether, etc. It is a compound in which an acrylic acid group, a methacrylic acid group or an allyl group is bonded to at least one OH group at the terminal by condensing with either or both of propylene to increase hydrophilicity by an oxyethylene group.

The ester or allyl ether compound of the compound (i) in the compound (b) is more specifically a compound obtained by the second step obtained through the following first step.

Further, the ester or allyl ether compound of the compound (ii) in the compound (b) is more specifically a compound according to the third step obtained through the following first step and second step.

In any of the above formulas, the line portion is represented by omitting the main chain of the polyhydric alcohol structure, and each symbol has the following meaning.

R ₁ ; fatty acid group having 6 to 30 carbon atoms or aliphatic alkyl group R ₂ ; hydrogen or methyl group R ₃ ; hydrogen or alkyl group Y; allyl group, acrylic acid group or methacrylic acid group, and 2 <m + n < Is 100.

In these compounds (i) and (ii), the compound (i)
The practical examples of sorbitan monolaurate monoacrylate: sorbitan monostearate
Monoacrylate: Examples include sorbitan, monooleate, monoacrylate, and the like.

In addition, as a practical compound (ii), polyoxyethylene sorbitan monostearate monoacrylate, polyoxyethylene sorbitan monostearate monoacrylate, polyoxyethylene sorbitan monooleate monoacrylate , Polyoxyethylene / sorbitan / monooleate / monoacrylate and mixtures thereof.

The amount of the compound (b) used is such that both the compounds (i) and (ii) are used in the range of 10.5 to 1.5% based on the monomer composition.

If the amount of the compound (b) used is less than 1.5%, the salt resistance of the copolymer is lowered, the viscosity is lowered by the counterions, and the transparency of the liquid is hindered by the use.

On the other hand, if it exceeds 10%, various functions such as thickening, water absorption and water retention are deteriorated and desired excellent performance cannot be obtained.

In the present invention, the compounds described below may be copolymerized with the compounds (a) and (b) as a crosslinking agent.

That is, a compound that is polymerizable with the compounds (a) and (b) and has two or more alkenyl ether groups per molecule of the base polyhydric alcohol containing two or more carbon atoms and two or more hydroxyl groups, respectively. A polyalkenyl poiether of a polyhydric alcohol, specifically, allyl pentaerythritol, trimethylolpropane diallyl ether, allyl saccharose and the like.

The compound added as the cross-linking agent is added in an amount of 5.0% or less with respect to all the constituents of the monomer.

Further, in the present invention, the compounds (a) and (b)
Further, other vinyl-based monomer having copolymerizability with these compounds may be added as a fourth component to the above-mentioned crosslinking agent added as necessary.

As the fourth component, the alkyl group has 1 to 4 carbon atoms.
There are alkyl acrylates or alkyl methacrylates, and specifically, ethyl acrylate,
Examples include butyl acrylate and methyl methacrylate.

The monomer as the fourth component is almost equal to the total amount of the monomer.
Use within the range of 10% or less.

The water-soluble acrylic copolymer of the present invention can be easily obtained by copolymerizing each of the above-mentioned monomers by an ordinary precipitation polymerization method or solution polymerization method.

The catalyst used is preferably a radical polymerization initiator of azo type, peroxide type, redox type or the like.

[Work]

The method for producing the water-soluble acrylic copolymer of the present invention,
For acrylic acid and / or methacrylic acid of (a),
(B) By copolymerizing a predetermined amount of the compound, a very high viscosity can be imparted at a predetermined concentration level, and the stability is maintained even in a thickened aqueous medium without being influenced by the salt therein. Keep

Therefore, when used as a viscoelasticity improver in a latex coating composition such as a water-based coating composition, excellent fluidity and homogeneity can be imparted.

When used for thickening textile printing pastes,
The performance can be remarkably improved in terms of easiness of preparation, compatibility with the pigment dispersion, gloss of the printed matter, and the like.

Further, in the present invention, a copolymer obtained by copolymerizing any amount of polyhydric alcohol effective for crosslinking with polyalkenyl polyether in an amount of 5% or less with (a) and (b) is obtained. It can be in the form of an appropriate three-dimensional network structure, and the copolymer thus obtained swells in an aqueous system to form a fine gel, and exhibits a more excellent effect in thickening, water absorption, water retention, etc. .

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to examples.

Examples 1 to 5 Acrylic acid was compounded as the compound (a) and polyoxyethylene sorbitan monolaurate monoacrylate was compounded as the compound (b) at a compounding ratio shown in Table 1 below (50 g). Then, nitrogen substitution was carried out with 450 g of benzene in a flask equipped with a condenser while stirring, 3 g of benzoyl peroxide was added as a catalyst, and the reaction was carried out at a temperature of 70 ° C. for 15 hours.

After cooling this, the precipitated copolymer powder was separated by a centrifuge and dried at a temperature of 55 ° C. to obtain a copolymer.
(Example 1) Similarly, as shown in Table 1, acrylic acid as the compound (a), polyoxyethylene sorbitan monostearate monoacrylate as the compound (b), and polyoxyethylene as the crosslinking agent (c). -Sorbitan monostearate diacrylate was copolymerized to obtain a copolymer. (Example 2) Further, methacrylic acid as the compound (a), polyoxyethylene sorbitan monooelate monoacrylate as the compound (b), and tetraallyloxyethane and polyoxyethylene sorbitan monooelate as the crosslinking agent (c). In addition to diacrylate, ethyl acrylate was blended as another copolymerizable monomer (d) that was the fourth component to obtain a copolymer. (Example 3) Further, methacrylic acid as the compound (a), the compound (b)
Was mixed with sorbitan monolaurate monoacrylate to obtain a copolymer. (Example 4) Further, sorbitan monostearate monoacrylate was compounded as the compound (a), and polyoxyethylene sorbitan monostearate monoacrylate was compounded as the compound (c) to obtain a copolymer. (Example 5) 1.0 g of the copolymer of each of the examples was put into 200 ml of distilled water, 1 ml of 10N NaO was added and dissolved, and the appearance of the solution was observed, and then salt was added to this. Then, the viscosity was measured.

The results are shown in Table 1, and the performance of polyacrylic acid and cross-linked polyacrylic acid, which are generally used as a thickener in the past, is also shown in Table 1 as a control.

[Effect of the Invention] In the method for producing a water-soluble acrylic copolymer of the present invention, at least acrylic acid or / and methacrylic acid, which are the compound (a), is the main component, and this and the compound (b) are in a predetermined quantitative ratio. It is possible to easily, easily and economically obtain a colorless transparent water-soluble acrylic copolymer excellent in salt resistance and ion resistance by copolymerizing with. Acrylic copolymers have applications across the other side.

That is, it can be used as a printing paste having an excellent thickening effect by blending it in a water-dispersed state or in an aqueous system to be thickened in a dry form, or as a latex for adhesives and paints.

In addition, for modification of cement and mortar, modification of ceramics such as ceramics and glazes, modification of cosmetics such as lotions and hair creams, modification of pharmaceuticals such as ointments and poultices, and addition to detergents. Therefore, its usefulness is fully demonstrated.

Further, the obtained water-soluble acrylic copolymer having good salt resistance is a water absorbent, a water retention agent, as a water retention agent for sanitary products such as paper diapers and napkins, a water retention agent for horticultural use, and as a retention agent for agricultural chemicals and fertilizers for agriculture, It can be used for a wide range of purposes, such as water-breathing wall material for construction, fire protection for fires, water leakage downstairs during fire extinguishing, and forest fire spread.

Claims (4)

[Claims] 1. A method for producing a water-soluble acrylic copolymer, which comprises copolymerizing at least the compounds shown in the following (a) and (b). (A) 90.0 to 98.5% by weight of acrylic acid and / or methacrylic acid (b) 10.0 to 1.5% by weight of higher fatty acid ester or higher aliphatic alkyl ether of polyhydric alcohol having at least 3 carbons and 3 hydroxyl groups And an ester or allyl ether compound of acrylic acid or methacrylic acid of a compound having at least one hydroxyl group at the terminal,
Alternatively, a higher fatty acid ester of a polyhydric alcohol having at least 3 carbons and 3 hydroxyl groups or a higher aliphatic alkyl ether to which ethylene oxide or / and propylene oxide is added, and at least 1 hydroxyl group is added to the terminal. Acrylic acid or methacrylic acid ester or allyl ether compound of the compound having 2. The compound (a) is neutralized with one or more compounds selected from alkali metal hydroxides, ammonia and amines. A method for producing a water-soluble acrylic copolymer according to item 1. 3. Copolymerization with the compound (a) and the compound (b) is carried out by using two or more alkenyl ethers per molecule of a mother polyhydric alcohol containing two or more carbon atoms and two or more hydroxyl groups as a crosslinking agent. A polyalkenyl polyether of a polyhydric alcohol having a group is added to each of the monomers in an amount of 5
The method for producing a water-soluble acrylic copolymer according to claim 1, characterized in that the components are blended in a proportion of not more than wt% and copolymerized. 4. A copolymerization component comprising the compound (a), the compound (b), and a cross-linking agent added if necessary,
The method for producing a water-soluble acrylic copolymer according to claim 1 or 3, wherein another monomer copolymerizable with these is blended and copolymerized.