JP2686824B2 - Process for producing dipentaerythritol hexaester compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a process for producing hexaacrylate or hexamethacrylate of dipentaerythritol.

Hexaacrylate or hexamethacrylate of dipentaerythritol (hereinafter these are collectively referred to as dipentaerythritol hexa (meth) acrylate)
Is easily polymerized by thermal decomposition of radical initiators such as peroxides, persulfates or azobis compounds, or by irradiation with ultraviolet rays or radiation to produce polymers with excellent heat resistance, light resistance, and oxidation resistance. . In addition, since it can be easily copolymerized with various vinyl compounds, the physical properties of the polymer can be adjusted according to the application, and it can be widely used as a raw material for resins, rubbers, adhesives, adhesives, inks, paints, coatings, etc. It's being used.

(Prior Art and Problems to be Solved) It is disclosed in JP-A-56-79637 that a perfluorosulfonic acid resin exhibits catalytic activity in the esterification reaction of general alcohols and carboxylic acids similarly to ordinary acid catalysts. Although already known from the description, the reaction rate is very slow in the method described therein, and particularly in the case of dipentaerythritol, which is hardly soluble, no esterification proceeds, and dipentaerythritol hexaacrylate is industrially produced. Cannot be realized as a general synthetic method. Further, as a method for producing a dipentaerythritol ester mixture, a method obtained by reacting dipentaerythritol with a small excess of acrylic acid or methacrylic acid (hereinafter, both are collectively referred to as (meth) acrylic acid) in the presence of an ordinary acid catalyst. JP-A-56-5143
As disclosed in JP-A No. 3 and JP-A-57-82343, since the amount of carboxylic acid used is in a small excess, the reaction temperature may be increased or the reaction time may be increased in order to allow the reaction to proceed smoothly. When it is made longer, oligomers and polymers of (meth) acrylic acid and dipentaerythritol hexa (meth) acrylate are by-produced, so problems such as low purity of the obtained product, high viscosity and remarkable coloring occur, Further, there is a drawback that the use of a large amount of acid catalyst increases the risk of corrosion of the reactor and the operational risk.

(Means for Solving the Problem) As a result of intensive studies aimed at improving the above-mentioned drawbacks, the present inventors have found that a strong acidic cation exchange resin is used as an acid catalyst and an azeotropic solvent is used. It has been found that the above object can be achieved by carrying out an esterification reaction in a solvent amount of (meth) acrylic acid while removing generated water out of the reaction system.

That is, the present invention, when producing a dipentaerythritol hexaester compound from dipentaerythritol and acrylic acid or methacrylic acid, in the presence of a strong acid cation exchange resin catalyst, dipentaerythritol and acrylic acid or methacrylic acid Equivalence ratio 1: 2 to 2
A method for producing a dipentaerythritol hexaester compound, which is characterized in that the reaction is carried out while water is separated by an azeotropic solvent at a ratio of 0.

As the strongly acidic cation exchange resin catalyst used in the present invention, a polyperfluoroalkylsulfonic acid resin,
Polystyrene sulfonic acid resins and the like can be mentioned, but perfluoroalkyl sulfonic acid resins are superior in terms of heat resistance and chemical resistance. The resin catalyst which is a heterogeneous catalyst is characterized in that it can be easily recovered from the reaction solution by filtration or the like and can be reused for the next reaction without regeneration treatment. The perfluoroalkylsulfonic acid resin, which is one of the heterogeneous catalysts of the present invention, may contain a carboxyl residue in the molecule. Also, the shape of the catalyst is a sheet,
Granular, etc. can be used. The amount of catalyst used is EW (equi
valent weight) value, but for example, EW value is 1
In case of 100 relative to the weight of dipentaerythritol
0.1 to 10 times, preferably 0.5 to 5 times is suitable.

The dipentaerythritol used in the present invention is produced by condensation of formaldehyde and acetaldehyde in the presence of alkali. Although commercially available products contain monopentaerythritol, tripentaerythritol, tetrapentaerythritol and the like in a proportion of several percent, the commercially available products can be used as they are in the present invention.

In the present invention, (meth) acrylic acid is equivalent to dipentaerythritol in an amount of 2 to 20 times, preferably 5 to
Used with 10 times the amount of solvent. If the amount of (meth) acrylic acid used is less than twice the equivalent amount, the physical properties of the product obtained will be problematic, and if it exceeds 20 times the yield per batch will be poor. A polymerization inhibitor is usually added to (meth) acrylic acid, but a polymerization inhibitor is further added in the reaction of the present invention. Polymerization inhibitors include p-methoxyphenol, hydroquinone, p-benzoquinone, p-
tert-Butylcatechol, nitrosobenzene, picric acid, dithiobenzoyl disulfide, cupric chloride, diphenylpicrylhydrazyl, tri-P-nitrophenylmethyl, N- (3-N-oxyanilino-1,3-dimethylbutylidene ) Aniline oxide and the like are used, and the amount thereof used is in the range of 0.01 to 1% by weight, preferably 0.1 to 0.5% by weight, based on (meth) acrylic acid. It is known that oxygen gas in the air also has a polymerization inhibiting effect, and it can be used in combination with the above-mentioned polymerization inhibitor.

The esterification reaction is carried out in the temperature range of 70 to 130 ° C., preferably 80 to 120 ° C. while preferably blowing air in order to prevent the polymerization of (meth) acrylic acid. The by-product water is
It is separated and removed from the reaction system while azeotroping with an aromatic hydrocarbon solvent such as benzene, toluene, xylene. The amount of azeotropic solvent used is 0.1 with respect to the weight of (meth) acrylic acid.
˜2 times, preferably 0.2˜equal amount. By controlling the pressure of the reaction system and keeping it slightly depressurized,
It is possible to carry out the reaction at a low temperature of ° C. In this case, it is advantageous that the amount of heat supplied to the reaction system is small and at the same time it is not necessary to forcibly feed air to prevent polymerization.

After the esterification reaction, the reaction solution is filtered to remove the catalyst, and the filtrate is a product only by removing excess (meth) acrylic acid and the azeotropic solvent under reduced pressure. The recovered catalyst, (meth) acrylic acid, and solvent can be subjected to the reaction again.

(Example) Example 1 50 g of dipentaerythritol was placed in one reactor equipped with a stirrer, a thermometer, an air inlet tube, a water separator, and a reflux condenser.
(0.2 mol), 170 g (2.4 mol) of acrylic acid, 0.17 g of p-methoxyphenol, 200 ml of toluene, 50 g of perfluoroalkyl sulfonic acid resin (Nafion 390, FW = 1100, made by DuPont), put in an oil bath while blowing air. The reaction was carried out while controlling the reaction temperature to 110 to 120 ° C. The produced water was removed by azeotropic distillation with toluene, and the reaction was terminated when the acid value of the reaction liquid became almost constant without distilling off the water. The reaction time was 4 hours. The catalyst was filtered off from the reaction solution, excess acrylic acid and an azeotropic solvent were distilled off under reduced pressure, the residue was dissolved in 2000 ml of toluene, then neutralized with a 20% aqueous sodium hydroxide solution, and washed with saturated brine. . Anhydrous magnesium sulfate was added to this and dried, and then toluene was distilled off under reduced pressure to obtain 108 g of dipentaerythritol hexaacrylate viscous liquid.

 The properties of the above product were as follows:

Bromine number 147 Saponification number 548 Hydroxyl number 47 Acid number 0.2 Viscosity (25 ° C) 3400 cp Refractive index (25 ° C) 1.4868 Also, dipentaerythritol hexaacrylate was prepared in the same manner as above using the recovered perfluoroalkylsulfonic acid resin. Although it was synthesized, there was no decrease in reaction rate and no abnormalities in the quality of the product were observed. Further, when the resin catalyst recovered from this reaction was used again to perform the same synthesis, the same result as above was obtained.

Example 2 Dipentaerythritol 50 g as in Example 1.
(0.2 mol), acrylic acid 850 g (12 mol), p-methoxyphenol 0.85 g, toluene 200 ml, and the reaction was carried out under the conditions of 250 g of the same perfluoroalkylsulfonic acid resin as in Example 1, dipentaerythritol hexaacrylate.
110 g were obtained.

 The properties of the above product were as follows:

Bromine number 140 Saponification number 555 Hydroxyl number 7 Acid number 0.2 Viscosity (25 ° C) 2500 cp Refractive index (25 ° C) 1.4901 Comparative Example 1 Dipentaerythritol 50 g in the same manner as in Example 1
(0.2 mol), 94 g (1.3 mol) of acrylic acid, 0.10 g of p-methoxyphenol, 100 ml of toluene, and 5 g of concentrated sulfuric acid were reacted to obtain 82 g of dipentaerythritol hexaacrylate.

 The properties of the above product were as follows:

Bromine number 115 Saponification number 509 Hydroxyl number 53 Acid number 0.2 Viscosity (25 ° C) 29200 cp Refractive index (25 ° C) 1.4925 Comparative Example 2 Dipentaerythritol 50 g as in Example 1
(0.2 mol), 94 g (1.3 mol) of acrylic acid, 0.10 g of p-methoxyphenol, and 50 g of the same perfluoroalkylsulfonic acid resin as in Example 1, the reaction was carried out under the conditions of no dehydration with an azeotropic solvent. No esterification reaction was performed.

(Effects of the Invention) Since the present invention uses a resin catalyst, there is no problem such as corrosion of the reactor, and the obtained product is excellent in quality. In addition, the used catalyst can be easily recovered and can be used successively.

Claims (1)

(57) [Claims] 1. When producing a dipentaerythritol hexaester compound from dipentaerythritol and acrylic acid or methacrylic acid, the equivalent amount of dipentaerythritol and acrylic acid or methacrylic acid in the presence of a strongly acidic cation exchange resin catalyst. A method for producing a dipentaerythritol hexaester compound, characterized in that the reaction is carried out while separating water by an azeotropic solvent using a ratio of 1: 2 to 20.