JPH08283336A - Method of stabilizing hydroxylated polymer - Google Patents

Abstract

PURPOSE: To solve the problem that a hydroxylated polymer obtained by reacting a carboxylated vinyl polymer with an epoxy compound increases in molecular weight with the lapse of time during storage. CONSTITUTION: A hydroxylated polymer obtained by reacting a carboxylated vinyl polymer with an epoxy compound is mixed with an acidic compound of a pKa of 3-10 to stabilize the polymer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a problem peculiar to a hydroxyl group-containing polymer obtained by reacting a polymer having a carboxyl group with an epoxy compound, that is, the molecular weight of the polymer increases with time during storage. It relates to a method of suppressing the.

[0002]

2. Description of the Related Art The introduction of a desired functional group into a polymer by reacting a polymer having a carboxyl group with an epoxy compound having an epoxy group and other groups is widely used industrially. It has been implemented.
For example, a macromonomer having a methacryloyl group as a polymerizable group, which is useful as a raw material for a graft copolymer, has been produced by reacting a vinyl polymer having a carboxyl group only at one end of a molecular chain with an epoxy compound such as glycidyl methacrylate.

However, a hydroxyl group-containing polymer and a hydroxyl group-containing macromonomer obtained by reacting a polymer having a carboxyl group with an epoxy compound as described above have a problem in storage stability and are stored at room temperature. There was a problem that the molecular weight gradually increased during the period. With respect to the above problem, the present inventors have further confirmed the following facts. That is, the hydroxyl group-containing polymer,
In addition to the hydroxyl group generated by the addition reaction of a carboxyl group and an epoxy group, it may contain a hydroxyl group-containing monomer unit as a polymer constitutional unit, but the storage stability decreases as the amount of hydroxyl group contained increases. Is.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a solution of a hydroxyl group-containing polymer obtained by reacting a polymer having a carboxyl group with an epoxy compound is added. The inventors have found that the addition of an acidic compound having a specific pka value does not cause an increase in the molecular weight of the polymer even when it is stored at room temperature for a long time, and have completed the present invention. That is, the present invention is characterized in that an acidic compound having a pka of 3 to 10 is added to a hydroxyl group-containing polymer obtained by reacting a vinyl polymer having a carboxyl group with an epoxy compound to stabilize the hydroxyl group-containing polymer. The method further, wherein the hydroxyl group-containing polymer is a radical-polymerizable macromonomer obtained by reacting a vinyl polymer having a carboxyl group only at one end of the molecule with an epoxy compound having an ethylenically unsaturated bond It is a method of conversion.

The present invention will be described in more detail below. First, a polymer obtained by reacting a vinyl polymer having a carboxyl group with an epoxy compound, that is, a polymer having a hydroxyl group generated by an addition reaction of a carboxyl group and an epoxy group (hereinafter referred to as a hydroxyl group-containing polymer) will be described. The vinyl polymer having a carboxyl group (hereinafter referred to as a carboxyl group-containing polymer), which is a starting material of the hydroxyl group-containing polymer in the present invention, is a vinyl polymer obtained by polymerizing a radical polymerizable monomer as described below. Coalescence is preferable, and a vinyl polymer having a polystyrene-equivalent number average molecular weight of 1,000 to 50,000 by gel permeation chromatography is more preferable. Unsaturated carboxylic acids such as (meth) acrylic acid, maleic anhydride and itaconic acid; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) acrylics such as stearyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and perfluoroalkyl (meth) acrylate Acid ester; (meth) acrylonitrile, vinyl acetate, vinyl propionate, styrene and the like.

The method of introducing the carboxyl group into the carboxyl group-containing polymer is not particularly limited. Specifically, for example, a method of polymerizing acrylic acid or methacrylic acid, or a chain transfer agent having a carboxyl group or 4,4′-azobis- (4-cyanovaleric acid)
There is a method by radical polymerization using a polymerization initiator having a carboxyl group such as The preferable amount of the carboxyl group in the carboxyl group-containing polymer is 0.02 to 2.0 mmol / g per unit weight of the polymer.

Examples of the chain transfer agent having a carboxyl group include mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid and thiosalicylic acid. By using a chain transfer agent having a carboxyl group and radically polymerizing a monomer having no carboxyl group in the presence of the chain transfer agent, a vinyl polymer having a carboxyl group only at one terminal of the molecule can be obtained. . The vinyl polymer serves as a starting material for a radical-polymerizable macromonomer.

Epoxy compounds having ethylenically unsaturated bonds such as glycidyl methacrylate, glycidyl acrylate and allyl glycidyl ether, as the epoxy compound to be reacted with the above carboxyl group-containing polymer, have hydroxyl groups such as glycidol and sec-butylphenol glycidyl ether. Epoxy compound; 3
-Glycidoxypropyltrimethoxysilane and 1-
Epoxy compounds having a silyl group such as [2- (trimethoxysilyl) ethyl] cyclohexane-3,4-epoxide; and butylglycidyl ether, phenylglycidyl ether, 2-methyloctylglycidyl ether, trimethylolpropane polyglycidyl ether, ethylene Examples thereof include glycol diglycidyl ether, neopentyl glycol diglycidyl ether, polyphenol type epoxy resin, ester type epoxy resin, and alicyclic epoxy resin. The epoxy compound is appropriately selected and used according to the purpose. For example, if an epoxy compound having an ethylenically unsaturated bond is used,
A radically polymerizable group can be added to the carboxyl group-containing polymer.

The reaction between the carboxyl group-containing polymer and the epoxy compound is usually carried out in a solution at a temperature of 70 to 70 ° C. in the presence of a catalyst.
It can be performed under the conditions of 140 ° C. and a reaction time of 1 to 20 hours. When an epoxy compound having an ethylenically unsaturated bond is used as the epoxy compound, it is desirable to add a polymerization inhibitor such as hydroquinone monomethyl ether to the reaction system. Since the reaction between the carboxyl group-containing polymer and the epoxy compound proceeds quantitatively by an equimolar reaction between the carboxyl group and the epoxy group, the amount of the carboxyl group in the polymer is equimolar or a slight excess of the epoxy compound is charged. It is preferable. In the above reaction, the epoxy compound is added to the carboxyl group-containing polymer while forming an ester bond, but at the same time a hydroxyl group is also generated by ring opening of the epoxy group.
A polymer having at least one hydroxyl group in the molecule, that is, a hydroxyl group-containing polymer is obtained. Furthermore, according to the present invention, as the hydroxyl group-containing polymer, a macromonomer having a radically polymerizable group at one end of the molecule can be obtained. Preferred organic solvents that can be used in the above reaction include tetrahydrofuran, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethyl acetate,
Butyl acetate, hexane, petroleum ether, mineral spirits and the like can be mentioned.

In the present invention, the acidic compound added to the hydroxyl group-containing polymer or radical-polymerizable macromonomer obtained by the above reaction is pka3 related to the acid dissociation constant.
Acidic compounds of 10 to 10, and examples of such acidic compounds include organic carboxylic acids such as acetic acid, propionic acid, acrylic acid, methacrylic acid and citric acid. In addition,
The pka in the present invention is a value based on the dissociation constant of an acid in an aqueous solution at 25 ° C. When an acidic compound having a pka of less than 3 is added, the hydroxyl group-containing polymer to be added causes a deterioration reaction. On the other hand, an acidic compound having a pka of more than 10 cannot suppress the increase in the molecular weight of the hydroxyl group-containing polymer during storage. The preferable addition amount of the acidic compound to the hydroxyl group-containing polymer is 0.001 to 0.5 mmol per 1 g of the polymer.
Is. If the addition amount of the acidic compound is less than 0.001 mmol / g, it is difficult to prevent the molecular weight from increasing with time.
If it exceeds 0.5 mmol / g, deterioration reaction of the polymer is likely to occur.

The present invention will be described more specifically below with reference to Examples and Comparative Examples.

Example 1 A flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube was charged with 200 g of toluene and 100 g of methyl ethyl ketone (hereinafter referred to as MEK), and the temperature was raised to 80 ° C. after purging with nitrogen. Then, in the flask, butyl acrylate 800 g, hydroxyethyl acrylate 200 g, toluene 300 g, MEK 200 g,
4 g of a mixed solution of 20 g of mercaptopropionic acid and 3 g of azobisisobutyronitrile (hereinafter referred to as AIBN)
It dripped over time. Subsequently, toluene 100g, M
A mixed solution of 100 g of EK and 3 g of AIBN was added dropwise over 2 hours and then aged at 80 ° C. for 2 hours to obtain a butyl acrylate / hydroxyethyl acrylate (80/20) copolymer having a carboxyl group at one end. To the obtained polymer solution, 29.5 g of glycidyl methacrylate, 1 g of hydroquinone monomethyl ether, and 5 g of tetraethylene ammonium chloride were added, and the mixture was heated at 80 ° C for 15 hours while bubbling air, and butyl acrylate / hydroxyethyl acrylate was added. A (80/20) copolymer macromonomer solution was obtained. The acid value of the solution is 0.02mgKOH /
It was less than or equal to g. The molecular weight of the macromonomer was 5,100 in terms of polystyrene equivalent and 11,000 in terms of weight average molecular weight. 2 g of acrylic acid was added to the obtained macromonomer solution. This is macromonomer 1
The ratio is 0.032 mmol per g. Table 1 shows the results of measuring the molecular weight of the macromonomer solution again after leaving it at 60 ° C. for 3 weeks.

[0012]

Example 2 Obtained by the same method as in Example 1,
2-ethylhexyl methacrylate / hydroxyethyl acrylate (86/14) having a carboxyl group at one end
(Weight ratio) A toluene solution of the copolymer is reacted with glycidyl methacrylate using tetrabutylphosphonium bromide as a catalyst to obtain a 2-ethylhexyl methacrylate / hydroxyethyl acrylate (86/14) copolymer macromonomer solution. It was The acid value of the obtained macromonomer solution was 0.02 mgKOH / g or less. The molecular weight of the macromonomer was 7,500 in terms of polystyrene equivalent and 16500 in terms of weight average molecular weight. 0.8 g of acetic acid was added to the obtained macromonomer solution. This is a ratio of 0.013 mmol per 1 g of macromonomer. The acetic acid-containing macromonomer solution was allowed to stand at 60 ° C. for 3 weeks, and as a result, the molecular weight of the macromonomer was as shown in Table 1.

[0013]

Example 3 A flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen introducing tube was charged with 500 g of ethyl acetate,
After purging with nitrogen, the temperature is raised to 80 ° C. 750 g of stearyl methacrylate, 150 g of styrene, 10 acrylic acids
A mixed solution of 0 g, 500 g of ethyl acetate, 10 g of AIBN and 5 g of mercaptoethanol was added dropwise over 3 hours. Subsequently, a mixed solution of 400 g of ethyl acetate and 10 g of AIBN was added dropwise over 3 hours, and the mixture was kept at 80 ° C for 2 hours.
After aging for a time, a stearyl methacrylate / styrene / acrylic acid copolymer was obtained. To this solution, 220 g of glycidyl methacrylate, hydroquinone monomethyl ether 1
g, tetrabutylammonium bromide (50 g), and heated at 90 ° C. for 10 hours while bubbling air, and a solution of a polyfunctional stearyl methacrylate / styrene copolymer in which all the carboxyl groups in the polymer have been converted to methacryloyl groups. Got The acid value of the above solution is 0.02 m
It was less than or equal to gKOH / g. The molecular weight of this polyfunctional copolymer was number average molecular weight; 15,000 and weight average molecular weight; 35,000. 10 g of propionic acid was added to the obtained polyfunctional copolymer solution. This is a ratio of 0.11 mmol / g of polyfunctional copolymer.

[0014]

Example 4 A flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen introducing tube was charged with 1000 g of toluene,
After purging with nitrogen, the temperature is raised to 90 ° C. Acrylic acid 2-
A mixed solution of 850 g of ethylhexyl, 100 g of hydroxyethyl methacrylate, 50 g of acrylic acid, 10 g of AIBN, and 5 g of mercaptoethanol was added dropwise over 3 hours. Subsequently, a mixed solution of 400 g of toluene and 10 g of AIBN was added dropwise over 3 hours, and the mixture was aged for 2 hours at 90 ° C. to obtain 2-ethylhexyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer. 3-glycidoxypropyltrimethoxysilane 180 was added to this solution.
g, triethylbenzyl chloride 30 g,
By heating at 0 ° C. for 10 hours, a solution of a polyfunctional 2-ethylhexyl acrylate / hydroxyethyl methacrylate copolymer in which all the carboxyl groups in the polymer were converted into trimethoxysilyl groups was obtained. The acid value of the above solution is 0.02 mg
It was KOH / g or less. The polyfunctional copolymer has a number average molecular weight of 16,000 and a weight average molecular weight of 3,420.
It was 0. Acetic acid was added to the resulting polyfunctional copolymer solution in an amount of 5
g was added. This is 0.07mm per multifunctional copolymer
Corresponds to ol / g.

[0015]

[Comparative Examples 1 to 4] A liquid obtained by not adding 2 g of acrylic acid in Example 1 is referred to as Comparative Example 1. The liquid obtained in Example 2 in which 0.8 g of acetic acid was not added was designated as Comparative Example 2. A liquid obtained by not adding 10 g of propionic acid in Example 3 is referred to as Comparative Example 3. A liquid obtained by not adding 5 g of acetic acid in Example 4 is referred to as Comparative Example 4.

[0016]

[Table 1]

[0017]

According to the present invention, it is possible to suppress an increase in the molecular weight of a hydroxyl group-containing polymer during storage, which is obtained by reacting a vinyl polymer having a carboxyl group with an epoxy compound. When the radical-polymerizable macromonomer stabilized by this method is copolymerized with another radical-polymerizable monomer, it becomes easy to control the molecular chain length of the branch component in the obtained graft copolymer.

Claims (3)

[Claims] 1. A method for stabilizing a hydroxyl group-containing polymer, which comprises adding an acidic compound having a pka of 3 to 10 to a hydroxyl group-containing polymer obtained by reacting a vinyl polymer having a carboxyl group with an epoxy compound. . 2. The hydroxyl group-containing polymer is a radical-polymerizable macromonomer obtained by reacting a vinyl polymer having a carboxyl group only at one end of the molecule with an epoxy compound having an ethylenically unsaturated bond. Stabilization method described. 3. The stabilizing method according to claim 1, wherein the amount of the acidic compound added is 0.001 to 0.5 mmol per 1 g of the hydroxyl group-containing polymer.