DE1420304A1 - Process for the production of oil-modified alkyd resins - Google Patents

Description

\ JuH! 958

Our No. 6562

California Research Corporation San Francisco, CaI., V.St.A.

Process for the production of oil-modified

Alkyd resins

The invention relates to a process for the production of oil-modified alkyd resins from a triglyceride higher fatty acid, a phthalic acid whose carboxyl groups are separated from one another by at least 3 carbon atoms, e.g. isophthalic acid or terephthalic acid, and a polyhydric alcohol, with the triglyceride and phthalic acid under Acidolysis react with each other.

The term "oil-modified alkyd resin" refers to all_ common to polymeric polyesters from polyhydric, preferably trihydric alcohols, e.g. glycerine and phthalic acids, in which the carboxyl groups are separated from one another by at least three carbon atoms, wherein in the polyester some of the polycarboxylic acid residues are replaced by the remainder of a fatty acid from vegetable or fish oils. As is well known oil-modified alkyd resins can be mixed with drying, semi-dry

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or non-drying oils.

One way of making oil-modified alkyd resins is the so-called "alcoholysis" process. In this procedure the first stage consists in heating the oil, which contains monocarboxylic fatty acid in the form of triglycerides, in the presence a catalyst, e.g. black lead or other metal oxides and hydroxides, with a polyhydric alcohol, whereby a mixture of partial esters of polyhydric alcohol and monocarboxylic fatty acids is formed. In a second stage this mixture of partial esters with a polycarboxylic acid or its anhydride, e.g. phthalic anhydride, becomes an im ) essential fully esterified alkyd resin with a low acid number condensed. Resins with different oil content, i.e. small, medium, large and very large proportions can be produced as triglyceride, depending on the relative oil content is calculated in percent by weight, based on the finished resin.

With the described preparation of alkyd resins according to the alcoholysis process, certain problems are connected, although they are a hindrance, but are accepted for lack of a remedy "For example, in the preparation of oil-modified Glycerylphthalatharze after the alcoholysis dee triglyceride with the polyhydric alcohol, the phthalic W anhydride can be added in two different ways. Either the reaction kettle is opened and the anhydride is added directly to the contents or the anhydride is pumped into the closed kettle in a molten state. The first possibility leads to the creation of undesirable vapors of water, acrolein and anhydride, which are regarded as industrial poisons and are also flammable. The second option requires the use of expensive corrosion-resistant devices.

Using isophthalic or terephthalic acid in the solid state instead of phthalic anhydride would be an expensive one System required to minimize the dangers that arise when the hot boiler is opened · Es

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It has therefore been proposed to change the sequence of the esterification stages by first reacting the triglyceride with the polybasic acid - a process known as "acidolysis" - and then adding the glycerol. While alcoholysis leads to the formation of a mixture of partial esters from polyhydric alcohols and monocarboxylic acids, "acidolysis" produces fatty acids and esters from the glyceride oil and the dibasic acid. However, it was fetsgestellt that certain of a successful acidolysis, unpredictable conditions of the starting materials must be respected and the process measures both in terms of, example, it has been observed * that simply changing the order of addition of reactants to the reaction kettle, heating together ie Phthalic anhydride and triglyceride oil with subsequent addition of glycerine does not lead to the desired results, since the acidolysis reaction of the phthalic anhydride with the oil does not take place and gelation disrupts the course of the reaction. If, instead of phthalic anhydride or o-phthalic acid, another phthalic acid, for example isophthalic acid, which reacts with triglyceride oil, is used, then it is desirable that the existing apparatus for alkyd production can be used for the acidolysis process without significant change. The devices usually used, however, are mostly exposed to restrictions with regard to the permissible temperatures, and often cannot be used at temperatures which are significantly above 280 °.

While, as stated above, the acidolysis reaction of phthalic anhydride with triglyceride oil could not be carried out independently of the temperature, the acidolysis reaction of phthalic acids of the isophthalic acid type with triglyceride oil can be carried out within a few minutes, provided that high temperatures of about 300 ° are used. The aci _do i _y g _e proceeds more slowly as the temperature is lowered. For example, if the

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forces the existing device to work at 260-280 °, too long a time is required to achieve the desired To achieve degree of acidolysis. Successful acidolysis at 300 ° cannot therefore be carried out in a conventional system.

An object of the present invention is therefore a process for the acidolysis of phthalic acids of the isophthalic acid type, which can be carried out successfully at temperatures of 280 ° or below and thus in a conventional system can be carried out.

Another that occurs in the acidolysis process for making alkyd resins from isophthalic or terephthalic acids The problem is that in the acidolysis reaction carried out at about 300 ° the polyhydric alcohol, e.g. the glycerine, at a much lower temperature, e.g. at 205 - 233 °, preferably 215 ° or below, must be added, which as a result of waiting for cooling There is a loss of time in the reaction mixture, which varies depending on the performance of the boiler cooling devices is big. This cooling is necessary because the introduction of glycerine or another polyhydric alcohol if the temperature is too high an explosive development of water takes place.

A further aim of the invention is therefore to eliminate the previously required cooling and to save the time lost by the cooling process.

In general terms, the invention is based on the finding that alkyd resins can be prepared from glycerol, a triglyceride oil and isophthalic acid by acidolysis at temperatures which can be used in conventional plants, namely at temperatures between about 260 and 280 °. The new process exists that a mixture of a triglyceride of a higher fatty acid and a phthalic acid, whose carboxyl groups are separated by at least three carbon atoms, at a temperature of about 260 to 280 ⁰ C.

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heated until the acidolysis ao between the mixed components that the acid number of the acidolysis product has progressed far is at least 100, then the reaction mixture while maintaining the reaction temperature polyhydric, preferably trihydric alcohol is added and heating is continued until complete esterification. Since the esterification with the release of water is endothermic, it must be avoided that the rate of addition of the glycerol affects the reaction temperature and causes the temperature to drop so that acidolysis is prevented. After adding the glycerine if the gas is heated further, the esterification proceeds and a light-colored resin with the desired acid number, generally below 25 and preferably below 10 is obtained. During the final heat treatment The temperature used depends on the degree of acidolysis reached during the addition of glycerine, with the temperature the higher the degree of acidolysis achieved, the lower it can be, but is high enough to cause the esterification to effect and prevent gel formation.

Experience this ^, wherein the acidolysis occurs simultaneously with the esterification and the transesterification, which avoids gel formation because the isophthalic acid acidolysierte oil and react rodukten the vacant fatty acids with glycerol to form acceptable ^x, while in contrast, the mixture of ' ^ glyceride oil and the gellable glycerine isophthalate is incompatible.

Obviously, acidolysis temperatures up to 280 ° are applicable in many alkyd resin cooking systems, while their practical Use above this temperature is not possible. The regulated addition of glycerin to achieve a rapid and complete acidolysis can be carried out successfully at any temperature of 260 ° or above. at At temperatures below 260 ° the acidolysis reaction becomes slower, so that, for example, at 249 ° a completely homogeneous and light-colored alkyd resin cannot be produced without reducing the time at which the glycerol is added to a practically unacceptable level Way is expanded.

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When producing light-colored alkyd resins that are free from cloudiness, veils or other signs of a gel structure, the regulated addition of glycerine or polyol to the heated mixture of isophthalic acid and glyceride oil is based on the aoidolysis reaction. While it was previously assumed that before the addition of the glycerol or polyol a complete acidolysis first had to be effected, either by using high temperatures or by using lower temperatures with reaction times that were practically too long, it has now been found that the aoidolysis before the introduction of the glycerol does not needs to be accomplished. Accordingly, when carrying out the acidolysis above a certain critical minimum, the glycerol can then be added all at once and the esterification can be carried out in the usual way. The degree of acidolysis can be determined by determining the amount of free fatty acid formed or by measuring the acid number of the acidolysis product. If the acidolysis product has an acid number of at least 100, the acidolysis has generally progressed to a sufficient extent that all of the glycerol can then be added in the usual way and the esterification can be carried out.

The acid numbers of the acidolysis products can be determined in the usual way, for example as follows: A hot sample is diluted with about 5 parts by volume of toluene and the unreacted isophthalic acid, which is insoluble in the hot toluene solution (94 ° above), is filtered off. The piltrate The oil thus obtained, which is a mixture of fatty acid isophthalic acid half-ester and unreacted triglyceride oil, is then titrated with 0.1N KOH in ethanol, the acid number being that for the neutralization of 1 g of oil The amount required is mg ¹ KOH.

It was found that the degree of acidolysis was lower than corresponding the above acid number can be if the

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Aoidolyae dea TriglyceridUls in the presence of a fatty acid is carried out. Ζ, Β, gives the heating of a mixture a reaction product from isophthalic acid and iriglyceride oil in the presence of a mola 'fatty acid per half of triglyceride oil with an acid number of 75 »the whole after adding de3 Glycerine leads to a light-colored, gel-free resin. In this Connection should be read that as a result of the presence of fatty acid in the specified amount at the beginning of the reaction, the acid number resulting from the acidolysis is only about 27, while using oil alone results in an acid number of about 100.

If one proceeds as described, gelation occurs during the reaction; or prevented, so that the simultaneous acidolysis and rasterization reactions can proceed smoothly and completely in a very short time. In the case of the alcoholic Lysee experience, the resin solutions are caused by the presence of catalysts ^. en cloudy or veiled and require a ^ ruckf iltrieru / ■ · -. ,. ι ν Generation of bright and clear solutions, Tm contrast here / -;? ■ ·. <V ^ xHi method according to the invention, no filtration required ..

example 1

A mixture of 1375 g (1.55 mol) of saffron oil and 915 g of isophthalic acid (5.51 mol) is heated to 260 °. Then the heated ^and emic are added during 1 hour and 19 Hinuten 4HG (4.50 mol) v / asaerfreles glycerol, wherein one bon at the temperature of the mixture is kept constantly 260 °. After adding the total glycerine, the mixture is heated for a further 41 minutes at 260 °, so that the total cooking time is 2 hours. The resulting resin is clear and light and has an acid number of 10,

In the procedure of this example we use the reaction temperature not kept at 260 ° all the time, but before or after

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If the glycerine is only added to e.g. 249 °, the resins become cloudy obtained, which indicates that the acidolysis has not proceeded to the required extent.

Example 2

A mixture of 1375 g (1.55 moles) alkali refined soybean oil and 915 g (5.51 moles) isophthalic acid is found Heated to 270 °, it is cooled slowly to 260 ° 414 g (4.50 moles) of anhydrous glycerin were added over 59 minutes. At this point, the degree of acidolysis is satisfactory reached, because lowering the temperature to 249 ° and further cooking for an hour lead to a bright and clear arz with an acid number of 10.

Example 3

A mixture of 1375 g (1.55 mol) of saffron oil and 915 g (5.51 mol) of terephthalic acid is heated to 260 °. Thereafter, 414 g (4.5 mol) of glycerol are added evenly to the heated mixture over 1 hour and 54 minutes and the whole is further heated at 260, so that the total heating time is 4 hours at 260 °. E ₃ produces a clear and light-colored resin with an acid number of 10.

Example 4

A mixture of 1375 g of saffron oil and 915 g of isophthalic acid is heated to 270 ° and kept at this temperature for 3 hours. Thereafter, a small Trobe is taken, diluted with toluene and he iss filtered to separate the oil from the unreacted ¹ Sοphthalsäure. It was found that the filtrate has an acid number of 108 after removal of the toluene. After cooling to 205 °, 414 g of anhydrous glycerol, reduced by the small amount required for the reaction with the removed sample, are added, and heating is continued to a final temperature of 249 ° until the acid number of the Resin 10 is. A clear and pale resin is obtained.

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In the procedure of this example, acidolysis is only used If carried out for half an hour or an hour, the acidolysis products show acid numbers of 36 and 58, respectively and do not give satisfactory resins.

■ "example 5

Example 4 is repeated, but in this case soybean oil is used used and the acidolysis carried out for one hour at 280, whereby an acidolysis product with an acid number of 101 is created. The resin is light-colored and shows no signs of a structure.

Example 6

A mixture of 1375 g of saffron oil and 915 g of isophthalic acid is heated to 300 °, whereupon the supply of heat is interrupted. Once the temperature has fallen to 288 °, Wä _r me is fed back, and 4HG anhydrous glycerine are then added for 21 minutes, after which the temperature is 229 °. The heating is continued at 249 ° until the total boiling time (except for the warm-up time) is 2 1/4 hours. The resin is light and does not have a gel structure.

Example 7

A mixture of 1043 g (1.18 mol) of linseed oil, 915 g (5.50 mol) of isophthalic acid and 338 g (1.18 mol) of fractionated tallow oil fatty acids is heated to 27 °, kept at this temperature for 30 minutes and then to 210 ° cooled down. A -frobe the product was diluted with toluene, filtered and showed the acid number of 80. Since the acid value of Gl-- ^d 'ettsäuregemischs was before heating at 48, had effected by the acidolysis of the acid number ^w ert 32, 451 g of glycerol ( 4.90 mol), reduced by the Heaktion with the extracted - ^ robe required amount, then added all at once whereupon the ^IJ - 'p _{e em} temperature of the reaction mass

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is about 182 °. It is then heated again and the Esterification carried out within 2 1/2 hours. The resulting resin is pure and bright.

Example 8

Example 7 is repeated with the change that the time of heating to 270 ° is reduced to 15 minutes, the acid number of the oleic acid product being about 75. The resulting resin is light.

In the method of this example, the ^ eit of heating to 270 ° reduced to 2 minutes, with an acid number of the oil ettsäure- ^ ^ roductS yields of 60, so an inappropriate _{RESIN w} ith gel ropes is obtained.

Example 9

A mixture of 1043 g (1.18 moles) saffron oil, 338 g (1.18 moles) fractionated tallow oil fatty acids and 915 g isophthalic acid is heated to 241 °, then 451 g (4.90 mol) of anhydrous Glycerin was added to the emiach at 241 ° for 86 minutes and heating is continued for an additional 1 1/3 hours at. The resulting resin is pure and light.

Example 10

Example 9 is made using '-i-'erephthalic acid instead of isophthalic acid repeated, but with the change that the temperature is 260 ° and the time for the addition of the Glycerin is 72 minutes. After another 1 2/3-hour heating at 260 ° the resin is pure and light.

In the preparation of the inventive resins, it is von'Vorteil when using an excess of glycerol, which is 10 to 25 i "over the stoichiometrically required for the reaction with the isophthalic acid amount. It is therefore expedient for each equivalent of isophthalic

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acid 1.1 Ms 1.25 equivalents of glycerin used. By changing the amount of triglyceride used in the acidolysis, the oil content of the resin, defined as percent by weight of the glyceride content based on the total resin weight, can be regulated as desired, but preferably within the range from 20 to 90 fo. The inventive method for producing the '-i ^'eilester with subsequent esterification can be in usual cooking vessels or carry ize boilers suitably ^u. These suitably contain heating and stirring devices, openings for feeding in the chemicals and for taking samples and, if oxidation by the air is to be avoided, inlets and outlets for an inert gas. After adding the glycerine, cooking is continued until a resin

is obtained with the desired acid number. In general a resin with a low acid number is preferred, e.g. resins with acid numbers below 25 and preferably below 10.

In the inventive method except terephthalic acid and isophthalic acid may also be mixtures of these · acids are used, and also substituted "isophthalic and I'erephthalsäuren containing among ^ eakticrusbedingungen inert substituents, such as" ethylterephthalic acid 5-tertiary butyl isophthalic acid or 2- ^{i i.}

The glycerol can be up to 25 fo by glycols such as ethylene glycol, diethylene glycol, ¹ 'riäthylenglyeol or propylene glycol replace%. Instead of Glycez-in, other polyols such as trimethylolpropane, pentaerythritol, mannitol or sorbitol can be used.

The glyceride used for acidolysis can come from a variety of sources, including those from fish. and plant origin, ^ s can be non-drying, semi-drying or desiccant ^ Ie can be used. Instead of the saffron oil used in the examples, others can be used Oils such as castor oil, corn oil, coconut oil, cottonseed oil, linseed oil, citicica oil, perilla oil, rapeseed oil, poppy seed oil, suntan

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"flower oil, tallow oil, tüngöl or the fish oils of herring, Menhaden and sardines, can be used.

If a fatty acid is additionally used in the acidolysis, any of the hydrolysis or saponification can be used for this purpose fatty acid derived from the glycerides used These include, for example, Capron-, Capryl-, Caprine-, Laurin-, Myristin-, Palmitin-, Stearin-, Arachidin-, Behen-, Oleic, castoroleic acid and tallow oil fatty acids, linseed oil, linolenic and licanic acids,

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Claims (2)

PATENT CLAIMS: 1. A process for the preparation of oil-modified alkyd resins, characterized in that heating a Gemiach of a triglyceride of a higher fatty acid and a phthalic acid, whose carboxyl groups are separated by at least three carbon atoms, to 260 to 28O ⁰ C, to between the mixing components, the acidolysis It has progressed so far that the acid number of the acidolysis product is at least 100, then a polyhydric, preferably trihydric alcohol is added to the reaction mixture while maintaining the reaction temperature, and heating continues until complete esterification. 2. The method according to claim 1, characterized in that the acidolysis is carried out by adding a fatty acid to the starting mixture is facilitated. For California Research Corporation San Francisco, CaI., V.St.A. 909818/1037 'Jeue documents in. 7 π down «. 2 No. ι s «te 3 * · XndenflHwoM. * 4.9. «Ι»;