JPS603295B2 - Method for producing low skin irritation oligomer - Google Patents

Description

[Detailed Description of the Invention] In recent years, with the aim of preventing pollution, preserving the environment, and saving labor, the development of solvent-free resins that can be cured by radiation energy such as light and electron beams has been actively carried out, and the practical application of these resins has been actively pursued. It is reaching a stage.

These curable resins have excellent storage stability and harden quickly once activated by energy irradiation, etc. A typical example of this type of resin is Q. , compounds that contain 3-unsaturated groups in the molecule, or compounds that have a vinyl group at the end of the molecule, especially those that have one or more acryloyl groups in the molecule, such as trimethylolpropane triacrylate and bentaerythritol triacrylate. Among them, the latter has excellent self-crosslinking properties.

However, these relatively low molecular weight polyol polyacrylates or coesterification reaction products containing these in high concentrations as production products (e.g. coesterification of trimethylolpropane, phthalic acid and acrylic acid) The resulting reaction product contains significant amounts of the by-product trimethylolpropane triacrylate)
In the process of handling them, health problems such as skin inflammation may occur, and it is desirable to take precautions to prevent such problems.

As a result of our intensive study to solve these problems, we found that
It reduces skin irritation to below a certain level and fully retains the excellent hardening properties that are the original characteristics of parentheses-type compounds.
In addition, they obtained knowledge of a method for producing oligomers that yields cured products with excellent physical properties, leading to the completion of the present invention.

The findings obtained by the present inventors are based on the analysis of the results of primary skin irritation tests conducted on various compounds having an acryloyl group. This is a widely practiced method and is subject to the Consumer Product Safety Commission of the U.S.A. in the Code of Federal Regulations, Title 1.
6, Section 1500.41 (The Consume
rProdMtSafetyCommlslonoft
heU. S. A. intheCodeofFedera
lRegulation. Title 16, Section
on1500.41), and the primary skin irritation index used in the present invention is the Primer Irritation Index (P
rima irritation index) - Abbreviation P
．． 1.1. − is. Details of this test method are as follows.

That is, a group of 6 or more white rabbits whose fur has been scaled with clippers is used, and 0.5' of the sample is applied to one location. The rabbit is immobilized, and the specimen is applied locally (paradorsal area on the back) using a patch method, and the body, including the patch area, is immediately covered with an impermeable material such as rubber or cloth for 2 hours. After 2 hours, the batch is removed and the local skin reactions are detected according to Table 1.

The rabbits were left as they were, and the skin reactions were scored again after 7 hours. Apply the same amount to abraded skin as to healthy 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 Skin peel 7 Judging time is also performed on skin with 0 abrasions.

Values for redness, arm skin formation, and water sore formation at 24 and 7 hours for healthy skin and scratched skin layers (total of 8 values)
is added and further divided by 4 to obtain the primary skin irritation index (P.
1.1. ) and P. 1.1. When the value is 2 or less, the primary skin irritation effect of the sample is judged to be mild, when it is between 2 and 5, it is judged to be moderate, and when it is 6 or more, it is judged to be a strong local irritation effect.

Table 1 As is already known to those skilled in the art, the co-esterification reaction products of polybasic acids, polyhydric alcohols and acrylic acids that were subjected to the primary skin irritation test are generally co-esterified with the by-product polyol polyacrylate. , a mixture of polyester polyacrylates with a degree of condensation of 1 or more, and as revealed in Table 2, this reaction product has a large P. 1.1. shows.

However, surprisingly, polyester polyacrylate with a degree of condensation of 1 or more, which has been separated and removed from polyol polyacrylate, has a small P.I. 1.1. I found out the facts that show that. For example, the reaction product obtained by coesterifying phthalic acid, diethylene glycol, and acrylic acid in a molar ratio of 1:2:2 has a compound represented by the following formula as the main component,
This compound has the structure of a polyol polyacrylate (in this case, diethylene glycol diacrylate) with a degree of condensation n of 0, and a polyester polyacrylate (n= In the case of No. 1, it is a mixture with pisjethylene glycol phthalate diacrylate), but the coesterification reaction product itself is shown in Table 2.
As shown in the wind, it has a large P. of 5.4. 1.1. shows.

On the other hand, in the polyester polyacrylate product after removing the by-product diethylene glycol diacrylate by preparative gel permeation chromatography (hereinafter abbreviated as G.P.C.), P. 1.1. decreases to 1.5. Similarly, the reaction product obtained by co-esterifying tetrahydrophthalic acid, trimethylolpropane and acrylic acid in a molar ratio of 1:2:4 has P. 1.1. is 2.7, but in polyester polyacrylate with a degree of condensation of 1 or more from which trimethylolpropane triacrylate is removed, P. 1.1. decreases to 1.0 or less.

Table 2 (Note n≧0; coesterification reaction product itself n≧1; polyester polyacrylate consisting of a component with a condensation degree of 1 or more obtained by removing boriol polyacrylate with a condensation degree of 0 from the coesterification reaction product) .

n≧2; polyester polyacrylate consisting of a component with a condensation degree of 2 or more, obtained by removing a component with a condensation degree of 0 and a component with a condensation degree of 1 from a coesterification reaction product.

Therefore, the present inventors have developed various acrylate F. 1.1. I thought that there might be a correlation between P.
1.1. I learned that there is a close correlation between molecular weight and molecular weight.

That is, as is clear from Table 3, the molecular weight of the acrylate is P. 1.1. is 2.0, and when the molecular weight is 450 or more, P. 1.1. is 1.5 or less, and most of them have a P. 1.1. is less than or equal to 1. Then, with molecular weight 350 as Sakai, P due to increase in molecular weight. 1.1. Therefore, the reduction effect of Table 3*1: Addition reaction product of 2 moles of bisphenol AI malt propylene oxide.

*2; Bisphenol AI mol and ethylene oxide 4
mole of addition reaction product. Based on the above knowledge, the present inventors
．． By co-esterifying polybasic acid, polyhydric alcohol and acrylic acid, P. 1.1. In order to produce oligomers with excellent properties and low skin irritation of 2 or less,
■Molecular weight of polyol polyacrylate to be created is 35
0 or more, and ■ Even if low molecular weight polyol polyacrylate with a molecular weight of less than 350 is produced as a by-product, it is essential to keep the amount sufficiently small. be.

The present invention provides a method for producing an oligomer by co-esterifying four components: a polyhydric alcohol consisting of a trivalent or higher polyhydric alcohol and a dihydric alcohol, a polybasic acid, and acrylic acid.

In this method, [a] a polyol polyacrylate produced from a trivalent or higher polyhydric alcohol and {b} 2
Diol diacrylate may be created from a dihydric alcohol, but as for {b}, dihydric alcohol has a specific structure. For example, dihydric alcohol with one ethylene oxide added to each hydroxyl group of bisphenol A ( It is limited to alcohols with a relatively high molecular weight, such as a molecular weight of 316), that is, a molecular weight of 245 or more. Therefore, the created polyol polyacrylate has a molecular weight of 350 or more and satisfies the above condition (2). Also, regarding 'a', there are some whose molecular weight is less than 35 degrees, so their P. 1.1 is likely to be high, but by using dihydric alcohol of polymer weir as mentioned above as polyhydric alcohol as raw material polyhydric alcohol, its content can be lowered, and the above condition ① I am also satisfied.

Examples of trihydric or higher polyhydric alcohols preferably used in the present invention include glycerin, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, triethanolamine, tris(2-hydroxyethyl)isocyanurate, These include glycerin tri(ethylene glycol) ether, bentaerythritol, diglycerin, triglycerin, xylitol, mannitol, sorbitol, and diventaerythritol.

In addition, polybasic acids and their anhydrides include succinic acid, adipic acid, sebacic acid, 1,12-dodecanedioic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, muconic acid, phthalic acid, and tetrahydrochloric acid. Phthalic acid, himic acid, endo acid, het acid, trimellitic acid, pyromellitic acid, etc., and anhydrides thereof are preferably used.

Furthermore, 2 represented by the above general formula having a molecular weight of 245 or more
Examples of the alcohol include divalent aromatic alcohols, that is, divalent phenols such as bisphenol A, bisphenol F, bisphenol PA, bisphenol S,
For hydroquinone, hydrogenated products thereof, and divalent aliphatic alcohols such as trimethylene glycol, tetramethylene glycol, hexamethylene glycol, etc., ethylene oxide, propylene oxide, or butylene oxa Some oxides are produced by reacting oxides, and the values of m' and n' in the general formula are determined depending on the number of moles of the oxides reacted. One specific example of two alcohols that are preferably used is (m'+n
') There is a product obtained by reacting moles of ethylene oxide, which is shown by the following formula.

m' and n' are integers, and the total value of m' and n' is 2-10. As a method for producing the oligomer according to the present invention, for example, the following method is preferably used.

That is, in a reactor equipped with a flywheel, a thermometer, and a moisture porcelain,
A raw material consisting of a polybasic acid or/and its anhydride, a trivalent or higher polyhydric alcohol, a dihydric alcohol represented by the above general formula, and acrylic acid, a reaction solvent that usually preferably serves as a dehydration entrainer, and esterification. A catalyst is charged, and water produced in the reaction is removed from the system as an aeotropic mixture with a dehydration azeotropic agent.

The end point of the reaction is determined by the amount of water produced as a by-product, etc. The reaction solution is washed with an alkaline aqueous solution and water, and after separating the aqueous layer,
Remove the dehydration entrainer under reduced pressure. By doing this, oligomers are obtained. In this case, in order to adjust the viscosity of the oligomer obtained as a product, after mixing other low-viscosity monomers and/or oligomers as a diluent into the reaction solution after washing, the dehydration entrainer is removed under reduced pressure. It is also possible to manufacture by a method. Further, this reaction can also be carried out by a two-stage reaction method in which raw materials are supplied in portions or by a sequential reaction method in which raw materials are added sequentially.

The charging ratio of each raw material in the present invention is determined based on the assumption that the oligomer produced by the method of the present invention has the structure shown by the following formula (model compound), and its theoretical value is shown in the table below. As shown in 4.

[Model compound]

Here, L is the residue of a polybasic acid (the number of carpoxyl groups is 1, but 2 or more), M is the residue of a trihydric or higher polyhydric alcohol (the number of hydroxyl groups is m, but 3 or more), and D is the residue The *residue of the dihydric alcohol represented by the above general formula, A is the residue of acrylic acid, and n, , n2 represent the degree of condensation (however, each is 0 or more).

Table 4 The theoretical amount of water produced when the above required number of moles of each raw material is reacted is calculated using the following formula. White*ru.

Amount of water produced = (lm-11m+2)n, ten (lm-2h-
114) n20 (lm--m+4)...Formula {5'
It is desirable that the specific charging ratio of each raw material satisfies the following conditions at the same time: Condition 1: The molecular weight of the model compound is 600 or more, preferably loo0 to 4000.
shall be.

Condition 2: Acryloyl group in model compound (C ratio =
CH-CO-...Molecular weight 55) Content is 5% or more of the model molecular weight, preferably 10% to 35% Condition 3: The acid and alcohol are preferably equivalent.

When calculating the raw material charging ratio, first the raw material polybasic acid and 3
Determine the type of polyhydric alcohol with a higher value (this results in 1
, m are determined), then the molecular weight formula of the model compound is established under condition 3 using the above formulas {1' to '5' (variables in this formula are n, , n2).

Furthermore, two equations are derived from this molecular weight formula, conditions 1 and 2, and by solving these, n, , n2 are determined (provided that n, ≧0, and the peak ZO).

The charging ratio of raw materials is determined by calculating the number n,. In Condition 3, the ratio of acid and alcohol to be charged was basically equivalent, but it is permissible for the equivalent ratio to vary within the range of 0.9 to 1.2.

Furthermore, as raw material acrylic acid, in addition to acrylic acid itself, lower alkyl esters of acrylic acid and acrylic acid halides can undergo reactions similar to esterification through transesterification and addition reactions. Various derivatives of acrylic acid may also be used.

In addition, there are many examples where the coesterification reaction of polybasic acid, polyhydric alcohol, and acrylic acid is described as if a single compound is obtained, but as in many other documents, Also, the product G. P. C. As revealed from the analysis, it is by no means a single compound, but generally consists of a mixture of polyol polyacrylate and polyester acrylate with different degrees of condensation and therefore with various structures and molecular weights.

Therefore, the oligomer obtained as a product of the coesterification reaction in the present invention is actually a mixture containing a polyester polyacrylate having a degree of condensation of 1 or more as a main component and a polyol polyacrylate as a minor component.

The heating temperature in the coesterification reaction is preferably about 50 to 150°C, and the reaction can be carried out at normal pressure, reduced pressure, or increased pressure.

As the dehydration entrainer, n-hexane, n-pentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, trichloroethylene, tetrachloroethylene, methylchloroform, diisopropyl ether, etc. are preferably used.

Further, as the esterification catalyst, common esterification catalysts such as sulfuric acid, hydrochloric acid, phosphoric acid, boron fluoride, P-toluenesulfonic acid, benzenesulfonic acid, and cationic exchange resins can be used as appropriate.

This reaction is preferably carried out in the presence of a polymerization inhibitor, and hydroquinone, methoxyhydroquinone, P-benzoquinone, t-phthylcatechol, phenothiazine, steel chloride and the like are preferably used as the polymerization inhibitor.

The oligomer obtained by the present invention has been confirmed to have extremely little skin irritation such as skin irritation in a primary skin irritation test, and provides a cured product that is fast-curing and has good physical properties.

Each oligomer is rapidly cured at room temperature to elevated temperature in the presence of a radical polymerization initiator, by irradiation with actinic light such as ultraviolet rays in the presence of a photoinitiator, or by irradiation with ionizing radiation. It has the properties of It is useful for applications such as coating agents and Katsura-type molding materials, and is particularly prized in the fields of ultraviolet curable paints and electron beam curable paints.

The present invention will be specifically explained below with reference to Examples.

Example 1 Tetrahydrophthalic anhydride, trimethylolpropane
2.2-bis{4-(2-hydroxyethoxy)phenyl}propane (a diol in which 1 mole of ethylene oxide was added to each hydroxyl group at both ends of bisphenol A) and acrylic acid were used as raw materials, the molecular weight of the model compound was 1000, and the model Coesterification was carried out using a raw material composition that complied with the condition that the acryloyl group content in the compound was 16.8%.

That is, 240 g of tetrahydrophthalic anhydride was added to a glass reactor of 3 capacity equipped with a Nadazusa reactor, a thermometer, and a water separator.
Trimethylolpropane 142, 2.2-bis {
4-(2-hydroxyethoxy)phenyl}propane 4
80 days, acrylic acid 220 days, toluene 1,500 days, para-toluenesulfonic acid 26 days, and phenothiazine 0.1 days.
I prepared 3 evenings.

It was heated while blowing air (840 cc'mjn).

When the overflow reached 100 CO, the water produced in the reaction began to distill out as an azeotrope with toluene. The azeotropic mixture was cooled and separated into a toluene layer and an aqueous layer, the toluene layer was returned to the reaction system, and the aqueous layer was extracted from the system. As the reaction progresses, the internal temperature rises, and after 6 hours, the internal temperature goes from 11 to 0.
The water yielded 81.7# crabs. The reaction solution was then cooled and washed with 250 g of a 10% aqueous sodium hydroxide solution, followed by 1240 g of a 7% aqueous sodium sulfate solution. After washing, 0.5 liters of methoxy/hydroquinone was added to the reaction solution, and toluene was distilled off under conditions of 40 to 5 0,2 side Hg to obtain a pale yellow oligomer 1103 as a residue. Toluene content was 9.3%. G. P. C.
The actual molecular weight was 1170 in number average molecular weight (hereinafter referred to as MN) and 283 in weight average molecular weight (hereinafter referred to as MW).
It was 0. Also, G. P. C. According to analysis, the peak height percentage (hereinafter referred to as HI) of low molecular weight polyol polyacrylate such as trimethylolpropane triacrylate in this oligomer was 0.85%.

Penzyl or penzoin ether as a photoinitiator was dissolved in this oligomer for several hours, and cold-rolled steel sheet (JIS
-G-3141, Bt#144 treated) in a 25 micron layer and dried in a dryer to evaporate residual toluene from manufacturing. After drying, the oligomer was irradiated with ultraviolet light and the curing properties of the oligomer were examined. The ultraviolet irradiation device was an ozone-type 2KW high-pressure mercury lamp [HiCureLampHI-20N manufactured by Nippon Battery ■ (input per unit arc length = 80W/arc) condensing device] was used. Ultraviolet curability is measured by the number of times a coated plate is exposed to ultraviolet light after being placed on a conveyor until the surface loses its tackiness. The adhesion and hardness of the cured coating were also investigated. Furthermore, the degree of influence of this oligomer on the skin was determined by a primary skin irritation test. These results are shown in Table 5 below, and an oligomer with low irritation and good curability was obtained. Example 2 Using the same raw materials and reactor as Example 1 and in the same manner,
Coesterification was carried out using a raw material composition that complied with the condition that the molecular weight of the model compound was 200 or more, and the acryloyl group content in the model compound was 16.8%.

284 g of tetrahydrophthalic anhydride in a glass reactor;
Trimethylolpropane 220 min, 2.2 bis {4-
(2-hydroxyethoxy)phenyl}propane 197
After that, 176 tons of acrylic acid, 1600 tons of toluene, 25 tons of para-tolesulfonic acid, and 0.12 tons of phenothiazine were charged.

When the internal temperature reached 103 qo, water produced by the reaction began to distill out as an azeotrope with toluene.

As the reaction progresses, the internal temperature rises and after 5 hours, the internal temperature reaches 1
At 0900 the water came out with 72.8 crabs. The reaction solution was cooled and washed with 280 g of a 10% aqueous solution of caustic soda, followed by 1200 g of a 7% aqueous solution of sodium sulfate.
I washed it in the evening. Add 0.4 methoxy/methoxy to the reaction solution after washing.
- Hydroquinone was added, and toluene was distilled off under conditions of 40 to 5000 Hg on both sides to obtain a pale yellow oligomer 1070 as a residue.

Toluene content was 25.3%. G. P. C. The actual molecular weight of the oligomer is MN=1280MW=3
It was 830.

Also, G. P. C. According to analysis, m of low molecular weight polyol polyacrylate such as trimethylolpropane triacrylate in this oligomer was 1.5%.

Furthermore, the results of the UV curability, paint film adhesion, hardness, and primary skin irritation tests of the oligomer conducted in the same manner as in Example 1 are shown in Table 5, indicating that the oligomer has low irritation and good curability. An oligomer was obtained.

Example 3 Using the same raw materials and reactor as Example 1 and in the same manner,
A co-esterification reaction was carried out using a raw material composition that complied with the following conditions: the molecular weight of the model compound was 3000, and the acryloyl group content in the model compound was 8.4%.

241 g of tetrahydrophthalic anhydride in a glass reactor;
Trimethylolpropane 73, 2,2-bis{41(
408 tons of 2-hydroxyethoxy)phenylpropane, 76 tons of acrylic acid, 1500 tons of toluene, 23 tons of para-toluenesulfonic acid, and 0.12 tons of phenothiazine were charged.

When the internal temperature reached 103 qo, water produced by the reaction began to form an azeotropic mixture with toluene.

As the reaction progresses, the internal temperature rises and after 4 hours, the internal temperature reaches 1
The volume reached 10 qo and 41 ta of water was distilled out. Cool the reaction solution,
It was washed with 390 g of a 10% strength aqueous solution of caustic soda, followed by washing with 1090 g of a 7% strength aqueous sodium sulfate solution. After washing, 0.37g of methoxynohydroquinone was added to the reaction solution, and the toluene was removed under the conditions of 40 to 50qo and 2 Hg, leaving pale yellow oligomer 12 as a residue in the pot.
I got 50 evenings.

The toluene content was 41%. G. P. C. The actual molecular weight of the oligomer is MN=161 and MW=426.
It was 0. Also G. P. C. According to analysis, the HI of low molecular weight polyol polyacrylate such as trimethylolpropane triacrylate in this oligomer was 0.57%.

Furthermore, the results of the UV curability, paint film adhesion, hardness, and primary skin irritation tests of the oligomer conducted in the same manner as in Example 1 are shown in Table 5, indicating that the oligomer has low irritation and good curability. An oligomer was obtained.

Table 5 *1 Tetrahydrophthalic acid, trimethylolpropane,
The molar ratios of acrylic acid and 2.2''pis{4-(2[hydroxyethoxy)phenyl}propane in this order are shown.

*2 Indicates the number of irradiations until tack-free. *3 Adhesion of cured coating film was determined by cross-cut tape peeling test. It becomes 100% when peelability is 0. *4 For convenience, H
I was taken as the polyol-borea acrylate content in the oligomer.

Examples 4 to 9 Using the polybasic acid, trivalent or higher polyhydric alcohol, acrylic acid, and dihydric alcohol shown in Table 6 as raw materials,
The molecular weight of the model compound is 2000, and the acryloyl group content in the model compound is 16.8% (however, only in Example 8 is 2000%).
5%), the co-esterification reaction and various tests were conducted in the same manner as in Example 2, resulting in low skin irritation and good hardening properties as shown in Table 7. Obtained oligomers.

Table 6 Table 7 *1 The raw material molar ratios are shown in the order corresponding to the raw materials listed in Table 6.

Claims (1)

[Claims] 1. It is characterized by co-esterifying a polybasic acid or/and its anhydride, a trihydric or higher polyhydric alcohol, a dihydric alcohol having a molecular weight of 245 or more represented by the following formula, and acrylic acid. A method for producing a low skin irritation oligomer. H-(OR')_m'-O-Ar-O-(R″O)_n
'-H In the above formula, R' and R'' have 2 to 2 carbon atoms.
4 alkylene groups, m' and n' are integers m' and n'
The total value of is 2 to 10, and Ar is a divalent organic group selected from hydrogenated or not hydrogenated aromatic groups, alicyclic hydrocarbons, and aliphatic hydrocarbon groups.