JPH0637531B2 - Method for producing curable resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a resin which is curable and is useful in various fields such as casting materials, paints and laminates.

[Conventional technology and problems]

BACKGROUND ART Conventionally, unsaturated polyester resins and vinyl ester resins have been heavily used as radical curable resins for various purposes, and have shown practically sufficient performance. However, depending on the application, there are still some that cannot be sufficiently satisfied with these existing resins, and improvement is required.

One example is a large marble-like bath tub that is cast. The properties of the resin required for such a molded product are almost colorless and can be molded without cracks, and the resulting molded product has excellent boiling resistance and a good appearance. I won't.

As a result of conducting research on a resin suitable for such use, some of the inventors of the present invention have found that a polymer side chain obtained by ring-opening addition of an unsaturated alcohol to a polymer having at least one acid anhydride group. It was found that by using a polymer having an unsaturated bond in the chain as a casting resin, it is superior in appearance and crack resistance after casting to the conventionally used terephthalic acid type polyester resin. Proposed earlier (Japanese Patent Publication No. 47-25470).

However, in this type of unsaturated polymer having an unsaturated bond in the side chain, when an unsaturated alcohol in an equimolar amount to the acid anhydride group is used, the viscosity changes markedly with time, and about twice the amount of unsaturated alcohol is obtained. It turned out to be necessary. One of the reasons is that the reactivity of the acid anhydride group in the polymer is not sufficient,
It was estimated from the results of infrared analysis that the reaction of the acid anhydride group was stopped at about 50 to 60% in the catalysts such as organotin compounds and organotitanium compounds which have been used until now. .

Although tertiary amines are useful as catalysts, they tend to color the reaction resin and are undesirable.

[Means for Solving the Problems]

In order to solve this point, the present inventors have conducted a study on a catalyst that facilitates the reaction between the acid anhydride group in the polymer and the unsaturated alcohol, and as a result, the alkali metal alcoholate shows a good action. The present invention has been completed by knowing that the addition reaction between the acid anhydride group in the polymer and the unsaturated alcohol can be easily completed in a short reaction time.

That is, the present invention relates to the use of an alkali metal alcoholate as a reaction catalyst when a polymer having at least one acid anhydride group is reacted with an unsaturated alcohol to produce a polymer having an unsaturated bond in a side chain. The present invention provides a characteristic method for producing a curable resin.

Examples of the alkali metal alcoholate used in the present invention include lithium alcoholate, sodium alcoholate, and potassium alcoholate. However, in consideration of availability on the market, cost, etc., sodium alcoholate of a lower alcohol having 1 to 4 carbon atoms. Is preferred, and sodium methylate is typical.

The polybasic acid anhydride of the polymer raw material having an acid anhydride group is typically maleic anhydride, and other examples thereof include itaconic anhydride and citraconic anhydride.

These unsaturated acid anhydrides are copolymerized with copolymerizable monomers to synthesize a polymer having an acid anhydride group.

The copolymerizable monomer may be any liquid as long as it is liquid under the copolymerization conditions, and examples thereof include vinyl aromatics such as styrene, vinyltoluene and chlorostyrene, acrylic acid and methacrylic acid, and methyl, ethyl, butyl, hexyl or octyl thereof. In addition to esters with alcohol and the like, vinyl acetate, acrylonitrile, acrylamide and the like can be mentioned. It is also possible to use two or more of these in combination. The ratio of monomers to unsaturated acid anhydride groups is generally 99: 1 to 50:50, usually 95: 5 to 7
0:30 is suitable.

The copolymerization reaction can be carried out at 30 to 200 ° C. by adding an organic peroxide or azobisisobutyronitrile, which is usually used in a radical polymerization, to a thermal polymerization only by heating without a catalyst. It is more convenient to carry out since the polymerization inhibitor does not remain in the subsequent esterification step and the polymerization inhibitor acts effectively to prevent gelation.

The acid anhydride group-containing copolymer thus obtained has a uniform copolymerization composition and an appropriate degree of polymerization, and is used in the next esterification reaction step. Polymerization degree is 50-2,000
About 0 is suitable. If the degree of polymerization is lower than 50, the physical properties of the cured product of the curable resin are particularly low, and if the degree of polymerization is higher than 2,000, the reaction solution becomes highly viscous and inconvenient to handle, and gelation occurs. If it becomes easier.

As the unsaturated alcohol for reacting with the acid anhydride group in the polymer, a type having a (meth) acryloyl group, that is, 2-hydroxyethyl acrylate, 2-
Hydroxypropyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate are preferred, but allyl cellosolve and methylol acrylamide can also be used.

The reaction is carried out in the presence of a polymerization inhibitor and an esterification catalyst, 5
The reaction is performed at a temperature of 0 to 150 ° C. to produce a copolymer having a group having an unsaturated bond in the side chain and a carboxyl group. In addition, it is also possible to esterify the generated carboxyl group with an epoxy compound, if necessary.

The reaction ratio between the unsaturated alcohol and the acid anhydride group-containing copolymer is preferably such that the acid anhydride group in the copolymer and the hydroxyl group in the unsaturated alcohol are substantially in moles. If the saturated alcohol is excessive, the gelation is less likely. Practically, it is allowed to react in the range of 1.0 to 2.0 mol.

During the reaction, it is necessary to add a polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, phenothiazine and the like.

Further, the presence of a free carboxyl group is not preferable when the physical properties of the curable resin are required, for example, when the cured product is required to have alkali resistance. In such a case, esterification with an epoxy compound is required. Preferably. As the epoxy compound, an epoxy compound having a polymerizable unsaturated bond is preferable from the viewpoint of the curability of the curable resin. Typical examples thereof include glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, vinylcyclohexene monoepoxide and the like. When allyl glycidyl ether is used, the resin exhibits air-drying properties and is suitable as a room temperature to heat-curable coating material. Further, by using glycidyl methacrylate, it is possible to increase the crosslink density,
It is useful in the field of FRP where chemical resistance is required. Further, a saturated epoxy compound which easily reacts with a carboxyl group can be used together. As an example thereof, UNOX 201, 206, 207 and the like manufactured by UCC, Inc. in the United States can be mentioned.

The curable resin according to the present invention can also be cured by copolymerizing with a monomer as a monomer solution,
It is also possible to carry out the cross-linking by polymerizing unsaturated bonds of the polymer without using a monomer together.

The unsaturated polymer synthesized according to the present invention can be used in various fields such as casting, paint, lamination, and FRP. When applied to these applications, a reinforcing material, a filler, a coloring agent, a release agent, a heat It goes without saying that a plastic polymer or the like can be used in combination if necessary.

Next, the present invention will be further described with reference to examples.

Example 1 Production of Polymer Having Acid Anhydride Group (Styrene-Maleic Anhydride Copolymer) [I] A one-separable flask equipped with a stirrer, a reflux condenser, a heating dropping funnel, and a gas introduction tube was charged with 478 g of styrene.
Was charged, 40 g of maleic anhydride was added dropwise in a nitrogen gas stream at 125 to 130 ° C. over 3 hours, and then the temperature was maintained at the same temperature for 1 hour. Then, the temperature is lowered to 80 ° C. and 0.1 g of hydroquinone monomethyl ether is added to stop the reaction.

A colorless, low-viscosity styrene solution of copolymer [I] was obtained with a polymerization rate of about 43% by weight. A dimethylaniline addition test confirmed the absence of free maleic anhydride.

Synthesis of unsaturated polymer [A] having unsaturated bond (methacryloyl group) in side chain and evaluation of physical properties Polymer [I]
78 g of 2-hydroxyethyl methacrylate in 522 g
(About 1.5 mol per 1 mol of the acid anhydride group in [I]),
Add 3 g of sodium methylate and in air stream at 80 ℃
And reacted for 5 hours to effect esterification. Thus, a polymer having a Hazen color number of 30, a viscosity of 9.6 poise and having an unsaturated bond (methacryloyl group) in the side chain [A]
was gotten.

The infrared absorption spectrum of this polymer [A] is shown in FIG. As shown in FIG. 1, the absorption of the carbonyl group based on the acid anhydride that should exist at 1780 cm ⁻¹ is only shoulder, and instead, the absorption of carbonyl of carboxylic acid or ester at 1720 cm ⁻¹ appears largely, and the reaction is It was shown to be complete.

When the change in viscosity of the unsaturated polymer (A) was examined in a constant temperature bath at 40 ° C., it was stable with almost no change to 11.1 poise even after 2 weeks.

100 g of unsaturated polymer (A), Kayaku Nouri Co., Ltd.
System containing 2 parts of curing agent # 328E and 0.5 parts of cobalt naphthenate gelled after 25 minutes at 25 ° C, and the maximum exothermic temperature was 158
Reached ℃.

Comparative Example An unsaturated polymer [B] having a methacryloyl group in its side chain was produced in the same manner as in Example 1 except that the same weight of dibutyltin dilaurate was used instead of sodium methylate. The infrared absorption spectrum of this polymer is shown in FIG.

As shown in FIG. 2, the absorption at 1780 cm ⁻¹ is 1720.
It has almost the same absorption as cm ^-1 , and the reaction rate of acid anhydride group is about 50.
It was estimated to be about%.

The obtained unsaturated polymer [B] had a viscosity of 4.9 poise and a Hazen color number of 30.

In the storage test at 40 ° C., the viscosity increased to 38 poises about 10 times after 15 days.

Example 2 Methyl methacrylate 22 was placed in a one-separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a gas introduction tube.
5 g, 213 g of isobutyl methacrylate, 32 g of itaconic anhydride, 2.5 g of azobisisobutyronitrile, 370 g of methyl ethyl ketone were charged, and 75-80 in a nitrogen stream was charged.
2.5 g of azobisisobutyronitrile was added to the temperature at 0 ° C. and the mixture was polymerized for 11 hours to obtain a polymer having an acid anhydride group (methyl ethyl ketone solution). The polymerization rate is about 92 by gravimetric method.
%Met.

100 g of xylene, 0.1 g of hydroquinone monomethyl ether, 29 g of allyl cellosolve were added to this polymer solution.
(1 mol per 1 mol of acid anhydride group) and 3 g of lithium methylate were added, and the mixture was reacted under reflux of methyl ethyl ketone for 8 hours. As a result of infrared analysis, the reaction rate of acid anhydride groups was estimated to be about 81 mol%.

After the solvent was distilled off, an unsaturated polymer [C] having a Hazen color number of 50 and a viscosity of 5.9 poise was obtained.

To 100 g of this unsaturated polymer [C], 0.05 g of cobalt naphthenate was added, and after coating on a bonderite copper plate so as to have a thickness of 100 µ, it was cured at 80 ° C for 1 hour and 120 ° C for 2 hours.

When the physical properties of the obtained cured coating film were measured, the hardness was 2
H, the adhesiveness to the eyes was 100/100.

〔The invention's effect〕

Since the present invention is configured as described above, the esterification reaction of the acid anhydride group and the unsaturated alcohol proceeds smoothly,
Since it is possible to obtain a curable polymer with little change in viscosity with time and without coloring, it can be used in various fields such as casting materials, paints, and lamination.

[Brief description of drawings]

FIG. 1 shows the unsaturated polymer [A] obtained in Example 1.
Is an infrared absorption spectrum of. FIG. 2 is an infrared absorption spectrum of the unsaturated polymer [B] obtained in the comparative example.

Claims (1)

[Claims] 1. An alkali metal alcoholate is used as a reaction catalyst when a polymer having at least one acid anhydride group is reacted with an unsaturated alcohol to produce a polymer having an unsaturated bond in a side chain. A method for producing a curable resin, which is characterized.