KR0180006B1 - Improved dry neutralization process for liquid organic phases - Google Patents

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Description

Modified Dry Neutralization Method for Organic Liquids

The present invention relates to an improved process for the purification of pure, generally neutral, low volatility organic components containing reactive olefinic double bonds that are susceptible to polymerization or gelling. More specifically, the present invention seeks to provide an improved process for the purification of pure and low volatility organic components of this kind which are difficult or impossible to purify by distillation.

The problems presented by the present invention are explained below with reference to examples of a group of selected compounds which can be produced particularly advantageously using the method proposed in the present invention. However, those skilled in the art will readily appreciate that the present invention is not limited to the scope of the compounds of this particular group. The novel methods proposed by the present invention are comparable, and can be applied in any field of application that must solve technically appearing or freely occurring problems.

Low volatility polyfunctional esters of acrylic acid and / or methacrylic acid with polyalcohols, also hereinafter referred to as (meth) acrylates or polyfunctional (meth) acrylates, are polymerization inhibitors in the reaction mixture in the presence of an acidic esterification catalyst. It can be prepared by reacting the reactants by adding. This kind of (meth) acrylate is becoming increasingly important as a highly reactive component of, for example, radiation-curing systems. Examples of the polyhydric alcohols based on these esters include divalent to tetravalent aliphatic saturated alcohols and / or alkoxylated products thereof. Multifunctional (meth) acrylates of this kind are, for example, in surface treatment compositions, molding or coating compounds, and especially in anaerobic adhesives in adhesives, as paint resins for curing with electron beams or with UV-curable printing inks or It can be used as a component of the corresponding coating composition. However, there are many problems with these productions. The required product needs to be odorless and colorless, above all, with low acid value and high storage stability. The (meth) acrylates of the present invention generally cannot be purified by distillation because of their high molecular weight and high reactivity. Solvent-containing or solvent-free mixtures obtained as crude reaction products may also contain acidic catalysts and possibly acid residues resulting from esterification reactions, thus necessitating neutralization and purification to obtain non-distillation products of the desired quality. There is.

The present invention is based on the concept of the above neutralization and purification steps, the so-called dry neutralization step. Dry neutralization refers to an acidic component (catalyst, residual acid, etc.) by adding a dry and basic neutralizing agent, at least in practically no water and preferably completely, to an organic crude reaction product in the form of a liquid paste. After the desired residual acid value is obtained, the added solid paste is separated from the liquid organic phase.

However, during the development of industrial processes based on the above concepts, the properties of the product (e.g., the color of the reaction product and / or Or stability) was found to be adversely affected and therefore difficult to meet the specified requirements for the properties of the final product.

The various problems found will be explained by the following examples: The highly reactive (meth) acrylate systems of the present invention tend to gel by anionic polymerization upon the addition of finely ground and solid basic neutralizing agents. If the reaction temperature is raised to high temperature, neutralizing the acidic components present in the reaction mixture as desired will be a preferred reaction for anionic gelling. However, the elevated temperature then adversely affects the residual brightness of the neutralized product.

The present invention originates from mutually complementing the properties of a product that meets the purpose. The present invention teaches how, in terms of overall properties, the final product with the desired high quality level can be obtained despite the above problems.

Accordingly, the present invention is pure, generally neutral, having a reactive olefin double bond from a starting material containing an organic compound component with a small amount of acidic reaction components and / or corresponding ancillaries in the liquid phase by neutralizing and separating the salts formed. And a method for purifying a low volatile organic compound. The process according to the invention uses solid, fine powdered oxides, carbonates and / or hydroxides of alkali and / or alkaline earth metals in order to obtain pure products with low residual acid values and low color standard values without distillation. The neutralization reaction is carried out by a dry neutralization method, and then the organic liquid phase is separated from the fine powder solid phase. Oxides and / or hydroxides of alkaline earth metals may be used in combination with other insoluble, basic metal oxides in one specific embodiment of the present invention, but may be used on their own for dry neutralization.

In order to carry out the dry neutralization reaction, it is particularly important to use oxides and / or hydroxides of finely ground and particularly finely divided calcium and / or magnesium. Of these two alkaline earth metals, the corresponding compounds of calcium are of particular importance. In one preferred embodiment of the present invention, a finely ground solid containing calcium compounds of the kind mentioned above at least partly is introduced into a dry neutralization step. A particularly important implementation is characterized by the use of calcium hydroxide Ca (OH) ₂ and / or quicklime CaO. Particularly finely ground calcium hydroxides often provide an optimal balance between process variables that influence each other, such as residual acid value, color standard, thermal stress, settling time, and the amount of dry neutralizer used.

Another key variable not yet discussed in the present specification is the possibility of interaction between the dry neutralizer used in this type of system and the polymerization inhibitors commonly used. Also in this case, there is a possibility that interaction occurs due to the specific structure of, but not necessarily, any inhibitor or inhibitor system present on the one hand and the solid neutralizer used on the other hand. Details on this can be found in the patent application pending with this application. (D 8929 Method of inhibitor exchange in radiation-reactive olefinically unsaturated systems). In applying the technical methods described in the specification of the present invention, the practitioner will sometimes have to consider how far to inhibit the dry-neutralization reaction product after separating the solid phase. The inhibitor content of the purified reaction product is preferably adjusted to the desired value by adding more inhibitors. Basically, inhibitors belonging to the representative group of compounds of the present invention for inhibiting the initiation of undesired radical polymerization can also interact with the dry neutralizing agent at a somewhat higher rate and typically be partially removed from the reaction mixture by the dry neutralizing agent. have. Depending on the need to meet the final product for the inhibitory action, the removed radical inhibitor portion is desired or necessary to be recovered.

Another important process variable for the optimization according to the invention is the choice of temperature range for the dry neutralization process. Even solid systems selected according to the invention on the basis of oxides and / or hydroxides of alkaline earth metals, in particular magnesium and / or calcium, initiate anionic polymerization in the case of relatively high reactive olefinically unsaturated systems at room temperature or even at elevated temperatures. So that the reaction product can be gelled. Therefore, according to the present invention, the dry neutralization reaction is preferably carried out at a temperature in the range of about 50 ° C. or higher, in the range of about 60 to 100 ° C. and above all in the range of about 70 to 90 kPa, which is particularly effective. Temperatures in this range promote salt-forming neutralization reactions during initiation of the anionic polymerization. However, this increase in temperature increases the risk of undesirably darkening the color of the final product.

On the other hand, the above problems are overcome by limiting the selection of the dry neutralizer produced by the present invention. The color of the reaction product may also be influenced by the choice of the neutralization period. The following facts are observed in this regard:

The dry neutralization reaction according to the present invention proceeds slowly compared to salts produced from the ionic solution. In addition, the delay of this neutralization reaction is facilitated by two factors considered here: Because of economics and optimal protection of the reaction mixture which is basically unstable, preferably, a solid basic neutralizing agent is used only in slight stoichiometric excess. Thus the residence time of the neutralizing agent suspended in the liquid starting material should suitably be long enough to properly contact the solid and liquid or somewhat dissolved reactants. Moreover, the outer surface of each solid particle is applied relatively quickly with the specific salts produced, preventing the acidic components to be neutralized from penetrating deeper into the nucleus of the solid particles.

The dry neutralization process according to the invention can be carried out over a period of several hours, for example 3 hours or less and preferably 1 or 2 hours or less. However, in order to obtain the optimal conditions to be provided by the process according to the present invention, a treatment time of less than 1 hour and, in particular, less than 45 minutes to meet the required low residual acid value is sufficient. It may be appropriate to mutually adopt them. In a particularly preferred embodiment, the operating conditions are mutually adopted in such a way that residual acid values of 1 mg KOH / g substrate or less can be obtained for a period of about 30 minutes or less and preferably about 5 to 30 minutes. When calcium hydroxide is used as the dry neutralizer, the optimum can be adjusted for a treatment time of about 5 to 60 minutes, typically at the indicated temperature of 80 ° C. Therefore, according to the present invention, it is possible to establish a low residual acid value, which is preferably required at about 0.5 mg KOH / g substrate or less, and at the same time, maintain the color standard value of the non-distilled material at 2 or less and preferably about 1. Color standard values are measured by the Gardner method.

The following parameters of the process according to the invention are particularly important for developing the color standard in the final product:

It has been found that water present in the reaction product to be treated can adversely affect the development of color standard values. The basic aqueous solution of the present invention exhibits a more severe decolorizing effect than the dry, neutralizing agent in solid form, even at relatively small amounts under other optimum process conditions. According to the invention it is therefore preferred that the material to be neutralized and used as a liquid phase is initially introduced at least substantially in the anhydride phase. Any residual water in the water present in the substance to be purified can be removed by a known method such as using a cosolvent by azeotropic distillation or simply taking a vacuum for a sufficient time.

However, in the specific practice of the present invention, the same concept develops as follows: It has proved to be suitable to carry out the neutralization reaction at least partially under reduced pressure even when the liquid to be neutralized is originally anhydrous. When the neutralization reaction is carried out under reduced pressure, the water produced during the neutralization reaction is also removed from the reaction mixture to prevent or at least limit the self-generation of the basic aqueous solution during the neutralization reaction. It is suitable for this to carry out the neutralization reaction at a pressure in the range from about 1 to about 150 mbar, for example in the range from about 20 to 150 bar, with a pressure in the range from about 20 to 100 mbar being particularly preferred. In this way, the residual moisture content in the final product can be controlled to about 0.1% by weight or less, whereas in the case of dry neutralization of the standard crude product, when the neutralization reaction is terminated in a non-vacuum state, since the free acid component is present in the crude product, The content may be present at about 0.7 to 0.9 weight percent. These relatively high residual moisture contents can substantially lower the color standard of the purified final product.

The amount of the fine powdery basic accessory added in the neutralization step is primarily determined by the total amount of free acid component to be neutralized in the crude product. It is preferable to add the fine powder type neutralizing agent at least in practically stoichiometric amounts. Usually, it is suitable to use a slight excess of solid neutralizing agent. Also based on the total amount of acid present, the amount will typically not exceed about 2.5 to 3 times the stoichiometric amount required. It may be advantageous to use a stoichiometrically necessary amount of about 1.3 to 2 times the base.

It has been found by the present invention that the components required for the neutralization reaction can harmonize their special influences to be disclosed. Powdered calcium hydroxide can very effectively lower the residual acid value and induce a low color standard value. However, the low color standard value is only guaranteed if the contact time of the reaction mixture with calcium hydroxide is kept relatively short. As already mentioned, optimum results can be obtained by carrying out this in a period of about 10 to 30 minutes at the indicated temperature of 80 ° C. If there is sufficient reactivity between the inhibitor and calcium hydroxide, calcium hydroxide also exhibits a relatively strong effect on the residue of polymerization inhibitor remaining in the reaction mixture. In contrast, quicklime is a good neutralizing agent that exhibits relatively weak interactions with essentially saltable inhibitors. The combination of magnesium and calcium compounds of the kind mentioned above can improve the color standard with a suitable neutralizing effect. It may also exhibit relatively weak interactions with possible salt inhibitors. The combination of magnesium and calcium compounds of the abovementioned kind can exhibit an improved color standard with a suitable neutralizing effect. It may also exhibit relatively weak interactions with possible salt inhibitors.

As mentioned initially, the alkaline earth metal oxides or hydroxides selected by the present invention can also be used in the form of mixtures with other basic metal oxides or metal oxides capable of salting. Detailed examples thereof may include hydrotalcite. The combination of hydrotalcite and the basic calcium compound of the kind mentioned above not only effectively lowers the residual acid value but also shows particularly good color value in the final product.

hnlichen schichtionen..., Chimia 24, 99 내지 108(1970) 등의 문헌에 수회 기재되어 있다. 상기 화합물의 대량 생산을 위한 각종 가능한 방법들이 DE-OS 20 61 156에 기재되어 있다. 상기 화합물군 중 가장 잘 특징 지워진 대표 화합물이 광물로서 자연중에 생성되고 또한 합성적으로 생산할 수 있는 히드로탈사이트이다. 히드로탈사이트는 예를 들어 R. Allmann 등 저 Die Struktur des Hydrotalkitsm N. Jahrb. Mineral. Monatsh. 1969, 544 내지 551에 기재된 조성물 Mg₆Al₂(OH)₁₆-CO₃x4H₂O를 함유하는 마그네슘-알루미늄 히드록소카르보네이트이다.Hydrotalcites are mixed hydroxides having an inorganic basic structure that can be finely ground, prepared in an insoluble state, and exhibit a two-dimensional inorganic polyvalent cation where the internal crystalline charge is equalized by unstable interlayer anions. It is also known as a bilayer hydroxide and is described by R. Allmann Doppelschichtstrukturen mit brucit

hnlichen schichtionen ..., Chimia 24, 99-108 (1970) and others. Various possible methods for mass production of such compounds are described in DE-OS 20 61 156. The best characterized representative compound of the above compound group is hydrotalcite, which can be produced in nature as a mineral and also produced synthetically. Hydrotalcites are described, for example, in R. Allmann et al. Low Die Struktur des Hydrotalkitsm N. Jahrb. Mineral. Monatsh. Magnesium-aluminum hydroxycarbonate containing the composition Mg ₆ Al ₂ (OH) ₁₆ -CO ₃ x4H ₂ O described in 1969, 544-551.

The following examples illustrate the effects of the various dry neutralizers according to the invention, the respective effects that occur as a result of fluctuations in process variables, and the optimal results for which the various factors that determine the process according to the invention are determined according to the instructions of the invention.

Example 1

One liter-flask is charged with 800 g of esterification crude product consisting of 28 g toluenesulfonic acid, 1.6 g 2,5-di-tert-butylhydroquinone, 30.8 g acrylic acid and 739.6 g trimethylol propane + 3 EO triacrylate. The crude product is neutralized by stirring at a temperature of 80-40 ° C. while passing air at 10 L / hr. Based on the acid value of the crude product (acid value: 40 mg KOH / g substrate), 2 times the equivalent amount of base is used for the neutralization reaction.

Approximately 200 g of neutralized product is removed after 1,2,3 and 24 hours and filtered by pressure filtration. Table 1 shows the results obtained for the acid value of the product.

The temperature is lowered to 60 ° C. using only a base having an acid value of 6 mg KOH / g or less at a neutralization temperature of 80 ° C. Thereafter, a base having an acid value of 6 mg KOH / g or less is also used for neutralization at 40 ° C.

Example 2

1.5 Kg of esterified crude product (52.5 g p-toluenesulfonic acid, 3.0 g 2,5-di-tert-butyl hydroquinone, 53,9 g acrylic acid and 1390.6 g trimethylol propane + 3 EO triacrylate, OH number: 34 mg KOH / g, acid value: 38 mg KOH / g, Gardner color standard value: 1, HO content: 0040 wt%) was charged to 2 l-reactor and neutralized with 48.9 g Ca (OH) at 80 ° C. while passing air at 2 l / hr. . After 1, 2 and 3 hours of neutralization, one third of the product is removed and filtered by pressure filtration. Thereafter, neutralization is carried out at atmospheric pressure on the one hand and residual water is removed on the other hand under vacuum at 50 mbar. The results are shown in Table 2.

Changes in product properties with respect to pressure taken during neutralization Starting material: trimethylol propane +3 EO triacrylate

Acid value: 38 mg KOH / g

Hydroxyl number: 34 mg KOH / g

Gardner Color Standard Price: 1

Moisture content: 0.40 weight%

Example 3

1.0 kg of esterified product (as in Example 2) is charged to a 2 L-reactor and neutralized at a temperature of 80 ° C. under a pressure of 50 mbar while passing air at 20 L / hr. The amount of neutralizing agent is as follows:

26.2 g of Ca (OH); 32.5 g; 34.5 g; 37.5 g; 39.9g; 49.9 g

CaO 28.4 g; 37.8 g

After 1, 2 and 3 hours of neutralization, one third of the product is removed and filtered by pressure filtration. Table 3 shows the results obtained for acid, OH and color standard values.

Change of product properties with respect to neutralizer amount

Starting material: trimethylol propane + 3 EO triacrylate

Acid value: 38 mg KOH / g

Hydroxyl number: 34mg KOH / g

Gardner Color Standard: 1

Moisture content: 0.40 weight%

Example 4

1.8 kg of esterification product (as in Example 2) was charged to a 2 L-reactor and neutralized with 90.3 g Ca (OH) at 80 ° C. under a pressure of 50 mbar while passing air at 20 L / hr. About 200 g of product are removed after 10, 20, 30, 40, 50, 60, 120, 180 and 1440 minutes and filtered by pressure filtration. Table 4 shows the results obtained for the acid value, hydroxyl value and color standard value.

Change of product properties with neutralization time

Starting product: trimethylol propane + 3 EOtriacrylate

Acid value: 38 mg KOH / g

Hydroxyl number: 34mg KOH / g

Gardner Color Standard: 1

Moisture Content 0.40 Weight%

Example 5

1.0 kg of esterification product (35 g P-toluene sulfonic acid, 2 g 2,5-di-tert-butylhydroquinone, 38.5 g acrylic acid, 94.5 g neopentyl glycol + 2 PO diacrylate, hydroxyl number: 20 mg KOH / g, acid value: 40 mg KOH / g Gardner Color standard value: 1) Charged into a 2 l-reactor and neutralized at 80 ° C. under a pressure of 50 mbar while passing air at 2 l / h. Neutralizers are mixtures or combinations of relatively weak basic and relatively strong basic materials.

Mixture (1: 1 equivalent)

After 60, 120 and 180 minutes, one third of the product is removed and filtered by pressure filtration. Table 5 shows the results obtained for the acid value, hydroxyl value and color standard value.

Changes in product properties when using mixtures and combinations of neutralizing materials

Starting product: neopentyl glycol + 2 PO diacrylate

Acid Value: 40mg KOH / g

Hydroxyl number: 20 mg KOH / g

Gardner Color Standard: 1

Example 6

1551.7 g of esterified product consisting of 43.4 g P-toluenesulfonic acid, 2.5 g 2,5-di-tert-butylhydroquinone, 36.5 g acrylic acid, 1119.1 g trimethylol propane + 3 EO triacrylate and 350.2 g toluene (acid value : 18.0 mg KOH / g, hydroxyl value: 25.3 mg KOH / g, Gardner color standard value: 1 or less).

The neutralization reaction is carried out at atmospheric pressure and 80 占 폚. 36.9 g Ca (OH) 2; 27.9 g CaO and 20.1 g MgO (60 min) + 28.9 g Ca (OH) (120 min) and 25.6 g Hydrotylsite (60 min) + 19.9 g Ca (OH) 2 (120 min) formulation is used as neutralizing agent. After 1, 2 and 3 hours, one third of the product is removed and filtered by pressure filtration. Table 6 shows the results obtained for the acid value, hydroxyl value and color standard value.

Change of product properties when using solvent

Starting product: trimethylol propane + 3 EO triacrylate

(Soluble in toluene)

Acid Value: 18 mg KOH / g

Hydroxyl number: 25 mg KOH / g

Gardner Color Standard: Below 1

Claims (10)

At least one solid and fine selected from the group consisting of oxides, carbonates and hydroxides of alkali metals and oxides, carbonates and hydroxides of alkaline earth metals to obtain pure products with low residual acid values and low color standard values without distillation A small amount of acidic reaction component in the liquid phase, through neutralization and separation of the resulting salt, is characterized in that the neutralization reaction is carried out by dry neutralization using a powdered compound, and then the organic liquid phase is separated from the fine powder solid phase. Pure, neutral and low volatility polyfunctional (meth) acrylates having reactive olefin double bonds from starting materials containing a polyfunctional ester component of (meth) acrylic acid and polyhydric alcohols together with the annex or both How to purify. The method of claim 1, wherein the neutralization reaction is carried out using at least one compound selected from the group consisting of calcium oxide, calcium hydroxide, magnesium oxide and magnesium hydroxide and at least partially using the corresponding calcium compound. Purification method. The purification method according to claim 1 or 2, wherein the neutralization reaction time is less than 1 hour. The purification method according to claim 1 or 2, wherein the neutralization reaction is performed at a temperature of 60 to 100 ° C for 5 to 60 minutes. The process according to claim 1 or 2, wherein the neutralization reaction is carried out at least partially under reduced pressure, while removing water produced during the neutralization reaction under a pressure of 1 to 150 mbar. The purification method according to claim 1 or 2, wherein calcium oxide, calcium hydroxide or both thereof in a mixture with hydrotalcite is used for dry neutralization. The process according to claim 1 or 2, wherein the fine powdered neutralizing agent is used in at least stoichiometric amounts. The purification method according to claim 3, wherein the neutralization reaction time is up to 45 minutes. The purification method according to claim 4, wherein the neutralization reaction is performed at a temperature of 70 to 90 ° C for 5 to 60 minutes. 8. The process according to claim 7, wherein the fine powdered neutralizing agent is used in an amount of 1.3 to 2.5 times the stoichiometric amount.