JPS606346B2 - Manufacturing method of oligoester acrylates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing oligoester acrylates that have an extremely low content of vinyl polymers and are hardly colored.

Oligoester acrylates have important uses as reactive diluents in producing thermosetting resins that are flexible at low temperatures.

Conventionally, it has been known to produce oligoester acrylates by dehydrating and condensing dicarboxylic acids or their acid anhydrides, glycols, and acrylic acids in the presence of an esterification catalyst and a polymerization inhibitor.

However, when conventional oligoester acrylates are used as reactive diluents in the production of thermosetting resins, the presence of vinyl polymers in oligoester acrylates and the coloring of oligoester acrylates vary. was causing the problem.

In other words, when producing oligoester acrylates, the presence of vinyl polymers resulting from the polymerization of acrylic acids may cause the thermosetting resin obtained by using oligoester acrylates as a reactive diluent to be coated into a film. This has the drawback of causing cloudiness on the surface of the coating film or reducing the abrasion resistance and scratch strength of the coating film.

Furthermore, when producing oligoester acrylates, the polymerization inhibitor forms various complex and difficult-to-remove colored substances with the esterification catalyst and trace amounts of oxygen in the reaction system. There was a drawback that the thermosetting resin obtained using the above-described method did not become colorless and transparent, or that even if an attempt was made to color the thermosetting resin obtained in this way into a desired color, the color did not develop clearly. When the amount of polymerization inhibitor used is reduced to prevent coloration when producing oligoester acrylates, a large amount of vinyl polymer is produced, and sometimes a gelled product with a three-dimensional network structure is produced. On the other hand, if a large amount of polymerization inhibitor is used to suppress the formation of vinyl polymers,
Although the amount of vinyl polymer produced was reduced, the coloring of the oligoester acrylates was so severe that it was impossible to put the oligoester acrylates into practical use.

In other words, depending on the method for producing oligoester acrylates, it has not been possible to simultaneously suppress the production of vinyl polymers in oligoester acrylates and the coloring of oligoester acrylates. Therefore, the inventors conducted intensive research on a method for producing oligoester acrylates that have an extremely low content of vinyl polymers and are hardly colored, and as a result, they arrived at the present invention.

That is, the present invention provides a method for dehydrating and condensing dicarboxylic acids or their acid anhydrides, glycols, and acrylic acids in the presence of p-toluenesulfonic acid or benzenesulfonic acid as an esterification catalyst and a polymerization inhibitor. The present invention relates to a method for producing oligoester acrylates, which is characterized by adding phosphoric acid or hypophosphite.

Examples of dicarboxylic acids and acid anhydrides used in the method of this invention include phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid, 4-methylhexahydrophthalic acid, and 3-methylhexahydrophthalic acid.
-tetrahydrophthalic acid, 4-methyl-△4-tetrahydrophthalic acid, 4-methyl-△3-tetrahydrophthalic acid to 4-methyl-△1-tetrahydrophthalic acid, 3'6
- Endomethylene - △4 - Tetrahydrophthalic acid, 3
・6-endomethylene hexahydrophthalic acid, 3.4.
5060707-hexachloro-3,6-endomethylenetetrahydrophthalic acid, hexahydro-isophthalic acid,
Hexahydroterephthalic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, maleic acid, fumaric acid, itaconic acid, etc., and their acid anhydrides Things can be mentioned. Examples of glycols include ethylene glycol, 1,2-pro/gundiol, 1,
3-pro/gundiol, 1,4-butanediol, 1
q5-bentanediol, 1,6-hexanediol,
1,5-hexanediol, 1,7-hebutanediol, 1,8-octanediol, 1,9nonanediol, 1,10-decanediol, 1,12-dodecanediol, neobentyl glycol, 1,4-dihydroxycyclohexane , cyclohexane-1,4-dimethylol, 212-bis(4-hydroxycyclohexyl)propane, bis(4-hydroxycyclohexyl)methane, 4-hydroxycyclohexyl-2-hydroxycyclohexylmethane, m-xylylene glycol, diethylene glycol, triethylene glycol , polyethylene glycol, dibropylene glycol, polypropylene glycol, bisphenol A dioxyethyl ether, bisphenol A dioxypropyl ether, bisphenol F dioxyethyl ether, pisphenol F dioxypropyl ether, dipromoneobentyl glycol, etc. can be mentioned.

Acrylic acids are acrylic acid and methacrylic acid.

The oligoester acrylates used in the method of the present invention are produced by dehydration condensation from dicarboxylic acids or their acid anhydrides (A), glycols (B), and acrylic acids (C), and have the formula: C-B It is represented by A-B-nC (where n is 1 to 20).

In order to produce such oligoester acrylates, A:B:C=1:1.3-2.231.3-2.2
It is preferable to use a molar ratio in the range of . As the esterification catalyst, P-toluenesulfonic acid, benzenesulfonic acid, chlorobenzenesulfonic acid, naphthalenesulfonic acid, etc. can be used.

The amount of the esterification catalyst used is preferably 0.1 to 10% by weight, particularly preferably 0.5 to 5% by weight, based on the total amount of dicarboxylic acids or their acid anhydrides, glycols, and acrylic acids.

If the amount of esterification catalyst used is less than the above range, the dehydration condensation reaction rate will progress slowly, and if it is more than the above range, it will be difficult to control the dehydration condensation reaction rate and remove the esterification catalyst from oligoester acrylates. becomes difficult.
Known polymerization inhibitors can be used, such as hydroquinone, hydroquinone monomethyl ether, 2,5-di-tem-butylhydroquinone, p
Examples include butylcatechol and phenothiazine.

The amount of polymerization inhibitor used is preferably 5 to 10,000, particularly preferably 10 to 300, based on the total amount of dicarboxylic acids or their acid anhydrides, glycols, and acrylic acids.

If the amount of polymerization inhibitor used is less than the above range, the amount of vinyl polymer produced will increase, and if it is more than the above range, the oligoester acrylates will be colored. In the method of the present invention, the oligoester acrylates obtained as described above are treated with hypophosphorous acid, or with the following compounds, such as sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, magnesium hypophosphite, etc. Phosphite or mixtures thereof are added.

Hypophosphorous acid and hypophosphites may be used as they are or as an aqueous solution oThe amount of hypophosphorous acid or hypophosphites used is: dicarboxylic acids or their acid anhydrides, glycols, and acrylic acid. It is preferably 0.005 to 3%, particularly preferably 0.02 to 1% by weight, based on the total amount used with acids.

If the amount of hypophosphorous acid or hypophosphite used is less than the above range, the effect of preventing discoloration and suppressing the amount of vinyl polymerization will decrease, and even if it is more than the above range, there will be no particular effect. . In addition, in order to further enhance the effect of preventing coloration of oligoester acrylates, phosphorous acid or phosphite may be used in combination with hypophosphoric acid or hypophosphite as an adjuvant.

The amount of phosphorous acid or phosphite used is preferably 0.01 to 5% by weight based on the total amount of dicarboxylic acids or their anhydrides, glycols, and acrylic acids, and 0.0% by weight.
Particularly preferred is 5 to 1% by weight.

In the method of this invention, oligoester acrylates can be produced without using a solvent, but in order to efficiently remove the produced water as the dehydration condensation reaction progresses, it is recommended to use a solvent that coexists with water. preferable. Examples of the solvent include benzene, toluene, xylene, cyclohexane, n-hexane, and isopropyl ether.

As the solvent, one type of solvent or two or more types of solvents may be used. In particular, when a mixed solvent of 13 to 60% by weight of benzene and 87 to 3% by weight of toluene is used, the content of vinyl polymer in oligoester acrylates can be reduced compared to when a single solvent is used. I can do it.
The amount of the solvent used is preferably 50 to 30% by weight based on the total amount of dicarboxylic acids or their acid anhydrides, glycols, and acrylic acids.

When producing oligoester acrylates according to the method of the present invention, the operations include hypophosphorous acid, dicarboxylic acids or anhydrides, glycols, acrylic acids, esterification catalysts, and polymerization inhibitors. or any operation in which hypophosphite is added;
For example, the following operations are applied. That is, a predetermined amount of dicarboxylic acid or its acid anhydride, glycols, acrylic acids, esterification catalyst, polymerization inhibitor, and sub-phosphoric acid (salt) are added to the reactor, and if necessary, phosphorous acid (salt) is added to the reactor. ), add the solvent and heat while stirring. When the temperature inside the reactor reaches around 100 pm, the produced water comes out of the system. When a solvent is used, the produced water is mixed with the solvent and distilled out of the system. Changes over time in the amount of water released and the acid value of the reaction solution are measured, and the reaction is terminated when water distillation is completed and the shark value becomes constant. After cooling the reaction solution to room temperature, the reaction solution is thoroughly washed with water, a polymerization inhibitor is added to the obtained oil layer as necessary, and the reaction solution is heated under reduced pressure at a temperature below which double bonds do not react and gel. Volatile components are removed to obtain oligoester acrylates as a residue. The oligoester acrylates obtained by the method of the present invention have an extremely low content of vinyl polymers, exhibit almost no coloration, and show almost no change in colorless transparency over time. Nakatsuta.

Next, examples and comparative examples of the method of this invention will be shown.

In addition, the color of oligoester acrylates is JISK
6901 (1977) as Hazen color number.

Examples 1-9 In a 500° glass flask equipped with a reflux condenser, a water separator, a thermometer and a fly tube, as shown in the following table:
0.50 mol of carboxylic acids or carboxylic acid anhydrides, 1.06 mol of glycols, 1.08 mol of acrylic acids, a predetermined amount of esterification catalyst, a polymerization inhibitor, a solvent, and a 30% aqueous hypophosphorous acid solution or Phosphite was charged, and in Examples 8 and 9, phosphorous acid was further charged, and the mixture was heated and refluxed while stirring.

The water produced by the dehydration condensation reaction was co-extracted with the solvent and removed using a water colander. Changes over time in the amount of water released and the acid value of the reaction solution were followed, and the reaction was terminated when the water stopped producing crabs and the acid value became constant. After the reaction product solution was cooled to room temperature, it was washed several times with the same volume of water as the reaction solution using a separating funnel.

The solvent was removed by distilling the obtained oil layer under reduced pressure of 55 to 60 qo and 2 Hg to obtain oligoester acrylates as a residue. Comparative Example The same procedure as in Example 1 was carried out except that the 30% hypophosphorous acid solution was not used.

The results of the above Examples 1 to 9 and Comparative Examples are shown in the following table.

Table 1) Evil. ■, relative to the total usage of Obi■.

2) Evil.

(Total usage of 0.3) Toluene:
The weight ratio of benzene is 15:8Table continued 1) ■.

Claims (1)

[Claims] 1 When dehydrating and condensing dicarboxylic acids or their acid anhydrides, glycols, and acrylic acids in the presence of P-toluenesulfonic acid or benzenesulfonic acid and a polymerization inhibitor as an esterification catalyst, hypophosphorous acid or hypophosphorous A method for producing oligoester acrylates, which comprises adding an acid salt.