JPS6138181B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a method for producing polyester di(meth)acrylate with low skin irritation and low viscosity. Synthesis methods for producing polyester diacrylate from dicarboxylic acid, diol, and acrylic acid include a one-step method in which dicarboxylic acid, diol, and acrylic acid are reacted all at once, or a method in which dicarboxylic acid and diol are reacted, and the resulting polyester diol is converted into acrylic acid. A two-step method of reacting with an acid is generally adopted (Special Publication No. 1973-36956). The products obtained by these methods are by no means a single compound, but several types of diacrylate compounds with different molecular weights each exist in a certain composition ratio, as shown by the following general formula [] It is a mixture. A-G(-B-G-) _o A [] A: Acrylic acid residue B: Dicarboxylic acid residue G: Diol residue n: Degree of condensation of polyester diol skeleton. 0, 1, 2, 3... The average molecular weight of the product can be adjusted by the molar ratio of dicarboxylic acid and diol charged during synthesis, and the average molecular weight affects the viscosity of the product, so
Adjustment of the charging molar ratio is an important factor in producing polyester diacrylate. What kind of effect does such a difference in synthesis method or raw material molar ratio have on the product? An example of this relationship is a system using phthalic acid as the dicarboxylic acid and diethylene glycol as the diol.
Specific details are shown in Table 1.

[Table] The products obtained in this way are highly reactive, high boiling point, and low volatile compounds that have a wide range of uses, including solvent-free paints, inks, adhesives, crosslinking agents, and molding materials. Although this is expected and can be used, it cannot be said that the products produced by the conventional manufacturing methods mentioned above are free from skin irritation, not only those with low viscosity but also those with relatively high viscosity. It is said that the process of handling it in practice may cause health problems such as skin irritation. The inventors of the present invention conducted extensive studies to improve this drawback, and found that there is a relatively good correlation between the molecular weight of the product and the skin irritation, as shown in Table 2.
It was found that as the molecular weight decreases, the irritation level increases significantly.

【table】

[Table] Therefore, Product A in Table 1 was subjected to high-performance liquid chromatography and fractionated into fractions 1 to 3 shown in Figure 1, and the skin irritation of each fraction and Product ABC itself was investigated. As a result, it was found that fraction 3 of low molecular weight diacrylates (n=0) had skin irritation comparable to or higher than the product itself, while fractions of higher molecular weight diacrylates (n≧1) and 3 I realized that it was very mild, and I came to know that Fraction 3, a low molecular weight diacrylate, is a determining factor in skin irritation. The above product A was fractionated using a high performance liquid chromatograph [Toyo Soda Kogyo Co., Ltd.
Uses "HLC-807" manufactured by Co., Ltd. Column; TSK-GeI
G3000HG+G2000HG, solvent: chloroform]. Fraction 1 is a mixture of all components with n=2 or more,
Fraction 2 shows the component with n=1, and fraction 3 shows the component with n=0. According to NMR analysis, component a in the pattern is a non-acrylate compound and is an impurity that does not cause skin irritation. FIG. 2 shows the skin irritation of organisms A, B, and C listed in Table 1 and fractions 1, 2, and 3 of product A. The above skin irritation test was conducted by The Consumer
Product Safety Commitment of
The U.S. in the Code of Federal Regulations. Title 16, Section 1500.41 (The Consumer Product Safety
Commission of the USA in the Code of
Federal Regulations, Title 16,
Section 1500.41), and the primary skin irritation index used in the present invention is the primary irritation index obtained by this test method.
This is the primary irritation index (abbreviated as PII). Details of this test method are as follows. That is, use 6 or more white rabbits in a group whose hair has been sheared with clippers, and apply 0.5 ml of the sample to one spot. The rabbit is immobilized, a patch is applied to the specimen locally (on the paradorsal region of the back), and the body, including the patch, is immediately covered with an impermeable material such as rubber cloth for 24 hours. After 24 hours, the patch is removed and the reaction of the locally appearing skin follicle is scored according to Table 1. Leave the rabbit alone and rescore the skin reaction 72 hours later. Apply the same amount to abraded skin as to Jiankang skin. Care should be taken to limit skin abrasions to exfoliation of the stratum corneum and not to extend to the dermis and cause bleeding. 24 and 72 hour determinations are also made on abraded skin. The 24- and 72-hour redness and crusting values and the total blister formation values for healthy skin and abraded skin (total of 8 values) are added, and the value is further divided by 4 to obtain the skin primary irritation index ( PII), and when PII is 2 or less, the primary skin irritation effect of the sample is judged to be mild.
A score of 2 to 5 is considered to be moderate, and a score of 6 or more is considered to indicate strong local irritation.

[Table] The present inventors have thus learned that the skin irritation of the reaction product is most significantly controlled by the n=0 component among the various diacrylate components that make up the reaction product. As a means to achieve the goal of making the product less irritating, we began to consider the establishment of a production method that would ideally contain less of this substance. By the way, if the conventional one-stage or two-stage synthesis methods described above are employed, it is impossible to produce a polyester diacrylate that is low in skin irritation and also has a low viscosity. In other words, in order to reduce the content of the n=0 component in the product, there is a method of synthesis using a raw material molar ratio that increases the theoretical degree of condensation of the product.
In this case, the viscosity of the product will be high, and if it is synthesized with a raw material molar ratio that reduces the theoretical degree of condensation,
Although the viscosity is lowered, the content of n=0 components increases, increasing skin irritation. The relationship between the theoretical degree of condensation and the raw material molar ratio is N moles of dicarboxylic acid (anhydride): N moles of diol (N+1), where N is the theoretical degree of condensation. The present invention thus provides an improved production process which overcomes the above-mentioned drawbacks, the basis of which is the esterification of the initial dicarboxylic acid and/or its anhydride in an excess of diol, followed by the esterification of the remaining diol. A polyester diol is produced by removing the polyester diol, which is then acrylated in the coexistence of a reaction solvent. In the present invention, in order to reduce the viscosity of the product, it is intended that the polyester diacrylate in the product is concentrated at n=1,
For this reason, the molecular weight distribution of the polyester diol is first adjusted to n=1 by esterifying the diol and dicarboxylic acid and/or its anhydride in an excess of raw material diol, that is, under conditions such that the molar ratio of the former/latter is >2. diol diacrylate (n=0 component) in the acrylation step by concentrating and then removing the remaining diol.
The purpose of this is to suppress the production of and significantly reduce the content in the product, achieving the objectives of low viscosity and low skin irritation. Although polyester diacrylate has been described in detail above, polyester dimethacrylate has similar problems, although not as bad as diacrylate, and the present invention can solve these problems. The dicarboxylic acids and their anhydrides used in the present invention include succinic acid, adipic acid, sebacic acid, 1,12-dodecanedioic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid,
Muconic acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, hymic acid, endo acid,
Het's acid and the like and their anhydrides are preferably used. In addition, diols include ethylene glycol, diethylene glycol, triethylene glycol,
Tetraethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,6-hexanediol, 1,4-butanediol, 1,5
-Pentanediol etc. are preferably used. The following method is preferably used as the reaction method of the present invention. Pre-stage reaction: dicarboxylic acid and/or its anhydride, in a reactor equipped with a stirrer, thermometer and condenser
Charge diol and catalyst and heat. Esterification is carried out under normal pressure in a nitrogen stream, and the water produced in the reaction is cooled and removed using a condenser. The reaction end point is when almost no water is distilled out, particularly when the esterification rate is 90% or more. After the reaction, the remaining diol is distilled off under reduced pressure to obtain a polyester diol in which almost no raw material diol remains. Note that this reaction can also be carried out in the presence of a reaction solvent that also serves as a dehydration entrainer, which will be described later. Regarding the charging ratio of raw materials in this reaction, it is necessary to use an excessive amount of diol, that is, it is necessary to charge more than 2 mol of diol per 1 mol of dicarboxylic acid and/or its anhydride, and the preferred molar ratio of both is The ratio is dicarboxylic acid and/or its anhydride: diol = 1:3 or more,
The ratio is more preferably 1:3 to 10, even more preferably 1:3.5 to 4.5. If the amount of diol used is smaller than this, the molecular weight of the polyester diol and eventually the polyester di(meth)acrylate will increase, leading to an increase in viscosity.
Moreover, even if the amount is increased excessively, the effect on lowering the molecular weight will be weak, and the dealcoholization operation will be burdensome. The reaction temperature can be the esterification temperature normally used in polyester production, for example in the range of 150 to 250°C, preferably below the boiling point of the raw material diol, more preferably about 20 to 70°C lower than the boiling point. Catalysts can be the customary esterification, transesterification and polycondensation catalysts, which are described in the literature [eg City of Berlin, Akademie Verlag, 1975
“Polyester Fibers” by H. Ludewig, published in 2007.
(Polyeterfasern) see pages 104 and 113-121]
preferred are Lewis acid catalysts such as zinc chloride, tin chloride, aluminum chloride, ferric chloride, and boron trifluoride. The temperature for distilling off the diol under reduced pressure is preferably lower than the esterification temperature, preferably about 10°C to 30°C lower than the esterification temperature, in order to prevent the polyester diol to be obtained from having a high molecular weight. Post-stage reaction: In a reactor equipped with a stirrer, a thermometer, and a water separator with a condenser, the polyester diol produced in the first-stage reaction, (meth)acrylic acid, a reaction solvent that usually preferably also serves as a dehydration entrainer, and an acidic A catalyst and a polymerization inhibitor are charged and heated to effect acrylation. Acrylation is carried out in the presence of molecular oxygen, if necessary, and water produced in the reaction is removed from the system as an azeotrope with the reaction solvent. The reaction end point is when almost no water is distilled out, preferably at an esterification rate of 95% or more. The resulting reaction solution is neutralized and further washed with water to recover a solvent layer free of impurities.
The reaction solution that has been neutralized and washed with water is stripped at a low temperature under reduced pressure to remove the solvent, thereby producing and obtaining polyester di(meth)acrylate with low viscosity and low irritation. The charging ratio of raw materials in this reaction is (meth)acrylic acid per mol of polyester diol.
It is 1.8-2.8 mol. If the amount of (meth)acrylic acid used is smaller than this, the molecular weight of the polyester di(meth)acrylate will increase and the viscosity will increase. On the other hand, if the amount is too large, the amount of unreacted (meth)acrylic acid increases and the loss increases. The molecular weight of the polyester diol can be calculated from the hydroxyl value determined by the acetic anhydride/pyridine method using the following formula. Molecular weight of polyester diol=1000×2/hydroxyl value of polyester diol (mep/g) The reaction temperature is preferably about 80 to 150°C, and the reaction can be carried out under normal pressure, reduced pressure, or increased pressure. Reaction solvents include benzene, toluene, xylene, n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, octane, methyl isobutyl ketone, diisopropyl ether, and other organic solvents that form an azeotrope with water and are substantially separated from water. Or used as a mixture of two or more. The amount of reaction solvent used varies depending on the type, reaction temperature, etc., but as a general rule, it is used in the range of 10 to 80% by weight of the reaction solution. Examples of acidic catalysts include sulfuric acid, P-toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, ion exchange resins, or mixtures thereof, especially sulfonic acid catalysts, especially P-toluenesulfonic acid.
-Toluenesulfonic acid is preferred. The amount used is preferably in the range of 4 to 20 mol % based on the raw material polyester diol. Various copper salts such as hydroquinone, methoxyhydroquinone, P-benzoquinone, t-butylcatechol, phenothymazine, or copper chloride are used as polymerization inhibitors, and the amount used is 0.005 to 1 per (meth)acrylic acid used. % by weight, preferably in the range 0.01-0.2% by weight. If the molecular oxygen to be blown into the reaction solution is finely dispersed, it will be easily dissolved and the polymerization prevention effect will be improved. When injecting into the reaction solution, oxygen gas itself may be used, but dangers such as explosions can be avoided by using a diluent gas such as air, an air-nitrogen mixture, or an air-carbon dioxide mixture. NaOH, KOH,
Alkali metals such as Na ₂ CO ₃ , K ₂ CO ₃ , Na ₂ SO ₄ ,
A 1-10% aqueous solution of alkaline earth metal hydroxide, carbonate or sulfate is used. By mixing and stirring the reaction solution with such an aqueous alkaline solution, the acidic catalyst and unreacted (meth)acrylic acid are neutralized and extracted and removed into the aqueous phase. For washing, use water or NaCI, NaSO ₄ , NH ₄ CI,
An aqueous solution of a neutral salt such as (NH ₄ ) ₂ SO ₄ is used, which extracts most of the impurities into the aqueous phase. Solvent removal is carried out under reduced pressure at a low temperature of 90°C or lower, preferably 70°C or lower. The polyester di(meth)acrylate produced by the present invention is a highly polymerizable compound with a high boiling point and low volatility, and like the polyester di(meth)acrylate obtained by the conventional esterification method, it is free from radical It can be easily and quickly polymerized to give a cured product with excellent physical properties by using a polymerization catalyst or by irradiating active light such as ultraviolet rays using a photoinitiator, or by irradiating radiation such as electron beam. Yes, solvent-free paint,
It is used as a polymerizable material in a wide range of fields such as inks, adhesives, crosslinking agents, molding materials, and others. However, the polyester di(meth)acrylate produced by the present invention has the characteristics of low viscosity and low skin irritation, and has extremely large industrial applications. The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto. In the present invention, the esterification rate can be determined from the amount of dehydration at that time in each dehydration reaction of "dicarboxylic acid and diol (first stage reaction)" or "polyester diol and (meth)acrylic acid (second stage reaction)". It is calculated from the following formula. Esterification rate (%) = Water produced by reaction (g) / Theoretical amount of water produced (g
)×100 Although acrylic acid is used in the examples, similar results can be obtained using other methacrylic acids. Example 1 First stage reaction: Production of polyester diol. Phthalic anhydride 222 in a four-necked flask equipped with a stirrer, thermometer, condenser and gas inlet tube.
g, 1.5-pentanediol 624 g (molar ratio of 1.5-pentanediol to phthalic anhydride 4.0)
) and 0.8 g of zinc chloride were added and dissolved at elevated temperatures, then stirred while ventilating nitrogen gas to bring the liquid temperature to 168-179.
The reaction was carried out at ℃. Water produced by the reaction was taken out of the reaction system in a condenser section. The reaction was stopped when water (25.5 g) containing 94.5% of the theoretical value was distilled off (after 7 hours). The 1.5-pentanediol remaining in the reaction solution was distilled off under the conditions of 150°C and 3 mmHg, and a pale yellow polyester diol was obtained.
Obtained 480g. 1.5 in this polyester diol
- Pentanediol content was 1.6% [High performance liquid chromatograph "HLC" manufactured by Toyo Soda Kogyo Co., Ltd.]
801A”. Column: HSK Gel G3000H
+G2000H, solvent: tetrahydrofuran]. The average molecular weight was 416 (calculated from the hydroxyl value determined by the acetic anhydride/pyridine method). Post-stage reaction: Production of polyester diacrylate. In a four-necked flask equipped with a stirrer, a thermometer, a water separator with a condenser, and a gas blowing tube, add 416 g of polyester diol produced in the previous step and 144 g of acrylic acid.
(equivalent to a charging molar ratio of acrylic acid to polyester diol of 2.0), 840 g of toluene, 17 g of para-toluenesulfonic acid, and 0.042 g of phenothiazine.
g and air/nitrogen mixed gas (volume ratio 1/3).
The reaction mixture was stirred while aerating the mixture at a rate of 200 ml/min, and the reaction was carried out at a liquid temperature of 97 to 108°C. The toluene-water azeotrope produced and distilled during the reaction was separated into water and toluene in a water separator, the water was taken out of the reaction system, and the toluene was returned to the reaction system.
The reaction was stopped when water (35.5 g) containing 98.5% of the theoretical value was distilled off (after 2 hours). After cooling the reaction solution, add 250g of 5% caustic soda solution.
It was then washed with 430 g of an aqueous solution containing 7% sodium sulfate. 0.25 g of hydroquinone monomethyl ether was added to the toluene layer obtained after washing, and the mixture was heated to 3 mm at 50 to 55°C.
Toluene was distilled off under Hg conditions to obtain 470 g of pale orange polyester diacrylate. The first and second reactions were carried out in the same manner except that the molar ratio of 1.5-pentanediol to phthalic anhydride was changed to obtain a total of four types of polyester diacrylates. The content ratio of the constituent components of each polyester diacrylate was determined (methods are *4 and *5 in Table 1).
), and skin irritation was also investigated using the method described above. The physical properties of the obtained polyester diol (first stage reaction product) and polyester diacrylate (second stage reaction product) were as summarized in Table 4. According to this, it is understood that although all of the polyester diacrylates are hypoallergenic, an appropriate charging ratio of phthalic anhydride and 1.5 pentanediol is required in order to lower the viscosity.

[Table] Examples 2 to 5 The first stage reaction was carried out in the same manner as in Example 1 except that the combination of dicarboxylic acid and diol was changed (however, in Examples 2 and 4, the air/room nitrogen mixed gas was not vented). Subsequent reactions and tests were conducted to obtain polyester diacrylates with low viscosity and low skin irritation shown in Table 5. The molar ratio of raw materials in the first reaction was dicarboxylic acid:diol=1:4.

【table】 [Brief explanation of the drawing]

Figure 1 is a diagram showing the elution pattern when product A listed in Table 1 was fractionated by high performance liquid chromatography, and Figure 2 is a diagram showing the elution pattern of product A listed in Table 1,
FIG. 3 is a diagram showing the skin irritation of each category separated from B, C and product A.

Claims (1)

[Claims] 1. After esterifying a diol and a dicarboxylic acid and/or its anhydride under conditions such that the molar ratio of the former/latter is >2, a polyester diol is obtained by removing unreacted diol, and then the polyester diol is 1.8-2.8 per mole
1. A method for producing polyester di(meth)acrylate, which comprises reacting a molar amount of acrylic acid and/or methacrylic acid in the presence of a solvent.