JPH0699362B2 - Method for producing ether carboxylic acid metal salt - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improved method for producing an ether carboxylic acid metal salt, particularly an ether carboxylic acid alkali metal salt, which is useful as an organic chelating agent, and more particularly to maleic acid. The present invention relates to a method for producing a metal ethercarboxylic acid metal salt of high purity by suppressing the formation of fumaric acid in the production of an ethercarboxylic acid metal salt obtained by an addition reaction of carboxylic acid with oxycarboxylic acid.

Ether carboxylic acid metal salts have strong chelating ability and can be used for the purpose of sequestering effect. Among them, monosuccinic acid tartaric acid tetrasodium salt (I) and disuccinic acid hexasodium tartrate salt are reaction products of maleic acid and tartaric acid. Salt (II) is known to be useful as a builder for soaps and synthetic detergents.

[Prior Art] A large number of documents have been published on a method for producing an ethercarboxylic acid metal salt. For example, JP-B-51-30049, JP-B-54-7773, JP-B-56-14096, JP-B-57-61799 and the like disclose production examples of carboxymethyloxysuccinate. In addition, JP-A-62-252743 discloses a method for producing oxydisuccinate, and JP-A-62-253693.
JP-A-63-130554 and JP-A-63-130554 disclose a method for producing a monosuccinic acid tartrate salt and a disuccinic acid tartrate salt from maleic acid and tartaric acid, and application to a detergent builder.

According to these descriptions, oxycarboxylic acids such as glycolic acid, malic acid, tartaric acid and tartronic acid and maleic acid are added, and alkali metal hydroxides are added in the presence of an alkaline earth metal such as zinc and / or calcium. To PH10-13, organic acid salt concentration 20-60% by weight, reaction temperature 50-120 ℃
In many cases, the ether carboxylic acid metal salt is obtained by reacting for 0.5 to 10 hours. Further after this, by adding an alkali metal carbonate and removing zinc or alkaline earth metal as zinc carbonate or alkaline earth metal carbonate, an alkali metal salt of ether carboxylic acid is obtained, which is used for a detergent builder. ing.

[Problems to be Solved by the Invention] In such an addition reaction of maleic acid and oxycarboxylic acid, an insoluble organic acid salt is formed between the organic acid as a raw material and the above-mentioned metals. The higher the acid salt concentration, the higher the equilibrium arrival yield of the ethercarboxylic acid metal salt, which is preferable in terms of yield. However, on an industrial scale, it is necessary to carry out all the steps from the raw material charging to the addition reaction at a high concentration because the insoluble salt as described above is generated and the viscosity of the mixture is increased. Since a large amount of heat for neutralization must be removed by the neutralization reaction of, the stirring and heat removal are difficult. Therefore, it is preferable to charge the raw materials, neutralize, and carry out the addition reaction at a concentration as high as possible within the limit that stirring and heat removal are not hindered.

Therefore, commercially available malic acid, glycolic acid, oxycarboxylic acids such as tartaric acid are generally solid products, but when these solid products are used as raw materials, they are appropriately diluted with water in the addition reaction. There is a need to. On the other hand, industrially produced oxycarboxylic acids such as malic acid, glycolic acid and tartaric acid are generally obtained once as an aqueous solution of oxycarboxylic acid or a salt thereof in the production process. It is convenient to use this as a raw material because the step of concentrating and drying the oxycarboxylic acid or its salt can be omitted at the stage of producing them.

Therefore, it is preferable that the raw materials are charged in a slightly diluted aqueous slurry state, and the addition reaction is performed after concentrating to a concentration that does not hinder stirring or heat removal. However, according to various studies conducted by the present inventors, fumaric acid is by-produced during the concentration step, and fumaric acid by-produced is less likely to undergo an addition reaction with oxycarboxylic acid.
It was found that the yield of the ether carboxylic acid metal salt is lowered, and the purity of the ether carboxylic acid metal salt is further deteriorated. Fumaric acid is a byproduct of maleic acid undergoing cis-trans rearrangement during the concentration step to be converted to fumaric acid, and the addition reaction between maleic acid and oxycarboxylic acid is an equilibrium reaction. It is considered that this is because in the process of reversibly decomposing the produced metal salt of ether carboxylic acid into oxycarboxylic acid and maleic acid, decomposition into oxycarboxylic acid and fumaric acid occurs with a probability of about 50%.

Furthermore, zinc or alkaline earth metal is generally used in the addition reaction of maleic acid and oxycarboxylic acid, and a zinc ethercarboxylic acid salt or an alkaline earth metal salt is obtained. These are useful as chelating agents for collecting heavy metals. However, it is the ether carboxylic acid alkali metal salt that is useful for the detergent builder, and the ether carboxylic acid zinc salt or alkaline earth metal salt is not useful for the detergent builder. Therefore, the ether carboxylate zinc salt or alkaline earth metal salt produced by the addition reaction is contacted with an alkali metal carbonate or bicarbonate, and the zinc carbonate or alkaline earth metal carbonate deposited here is decanted, for example. Removed,
A step of obtaining an alkali metal salt of ether carboxylic acid is required. However, in the step, not only zinc carbonate or alkaline earth metal carbonate, but also a considerable amount of ethercarboxylic acid is discharged as waste in the form of some metal salt, which causes a decrease in the yield of ethercarboxylic acid itself. However, there are problems in terms of pollution, economics, and effective use of resources.

The object of the present invention is to overcome the above-mentioned problems, to prevent the fumarization of maleic acid to produce a high-purity ethercarboxylic acid metal salt in a high yield, and to perform a difficult operation or a complicated process from the viewpoint of industrial scale. An object of the present invention is to provide a method for producing an ethercarboxylic acid metal salt without requiring a large number of steps. Furthermore, in the step of obtaining an ether carboxylic acid alkali metal salt useful as a detergent builder, etc., a system for not only effectively recovering zinc or alkaline earth metal but also reusing it repeatedly in the manufacturing process is established. The purpose of the present invention is to improve the yield of the alkali metal salt of ether carboxylic acid and to establish a production method capable of significantly reducing waste.

[Means for Solving the Problems] The present inventors have found that when the addition reaction of maleic acid and / or maleic anhydride and oxycarboxylic acid is carried out in the presence of zinc and / or alkaline earth metal, the yield is high and The present invention has been completed as a result of intensive studies on a method for producing a metal ethercarboxylic acid salt with high purity. That is, the present invention contains (a) maleic acid and / or maleic anhydride, (b) oxycarboxylic acid, (c) alkali metal, (d) zinc and / or alkaline earth metal, and (a), (b) The ratio of the total base equivalent of the metals shown in (c) and (d) above to the total acid equivalent of the organic acid shown in (b) (hereinafter referred to as "base equivalent / acid equivalent").
Is concentrated in the range of 0.93 to 1.04, and then alkali metal is added to adjust the base equivalent / acid equivalent to 1.05 to 2.
It is characterized in that the maleic acid and the oxycarboxylic acid are subjected to the addition reaction by adjusting to the range of 0.

The maleic acid used as a raw material in the present invention is not limited to a free acid form, and may be a salt form with an alkali metal, zinc, alkaline earth metal or the like, and of course, maleic anhydride. But you can use it exactly the same. Further, the maleic acid, its salt or maleic anhydride may be in any form such as solid, slurry or aqueous solution, and may be in the form of circulating what is recovered by the method described below.

Examples of the oxycarboxylic acid include glycolic acid, tartaric acid, malic acid, tartronic acid, glyceric acid, lactic acid and oxypropionic acid. These oxycarboxylic acids may be alkali metal salts or zinc or alkaline earth metal salts obtained in the industrially produced process.
The shape of these raw material acids may be solid, slurry, aqueous solution, or the like. Further, it may be in a form in which the material collected by the method described later is circulated. Among the oxycarboxylic acids exemplified above, the above-mentioned monosuccinic acid tartaric acid tetrasodium salt (I) and disuccinic acid tartaric acid hexasodium salt (II) obtained especially when tartaric acid is used are particularly useful compounds as a detergent builder. is there.

Examples of the alkali metal include sodium and potassium, and preferably used as hydroxides such as sodium hydroxide and potassium hydroxide.

Calcium is particularly preferably used as the alkaline earth metal, but magnesium, strontium, barium and the like can also be used. Zinc and alkaline earth metals may be used alone or in combination of two or more, and may be used as various inorganic acid salts such as hydroxides, oxides and carbonates. It may also be recovered by the method described below.

In the present invention, first, (a) maleic acid and / or maleic anhydride, (b) oxycarboxylic acid, (c) alkali metal and (d) zinc and / or alkaline earth metal are added in a base equivalent / acid equivalent of 0.93 to An aqueous mixture is prepared by mixing so as to be within the range of 1.04, preferably 0.96 to 1.02. As an example of the basic procedure, maleic acid is added to an industrially obtained aqueous solution of an oxycarboxylic acid salt, and an alkali metal (for example, sodium hydroxide) and zinc and / or an alkaline earth metal (for example, hydroxide). Calcium) is mixed so that the base equivalent / acid equivalent is within the above range.

If the base equivalent / acid equivalent is less than 0.93, fumarization occurs by cis-trans rearrangement of maleic acid in the next concentration step, while if the base equivalent / acid equivalent is more than 1.04, the concentration step of the concentration step is increased. Since the addition reaction between maleic acid and oxycarboxylic acid progresses during this process, and this reaction is an equilibrium reaction, the ether carboxylic acid metal salt once produced reversibly reacts with oxycarboxylic acid and unsaturated acid (maleic acid and maleic acid). Fumaric acid decomposes in a ratio of about 1: 1).
The fumaric acid thus produced does not proceed with the addition reaction with the oxycarboxylic acid or is very slow even if it proceeds. Therefore, the longer the time required for concentration, the longer the heating is, so that the amount of fumaric acid produced as a by-product increases and the purity and yield of the ethercarboxylic acid metal salt decrease. However, when the base equivalent / acid equivalent is concentrated within the range of 0.93 to 1.04, the fumarization rate of maleic acid is very slow, and the addition reaction between maleic acid and oxycarboxylic acid, and thus its reversible decomposition Since the reaction also proceeds only moderately, a wide range of temperature and time is allowed for concentration.

The molar ratio of the total amount of maleic acid and / or maleic anhydride, oxycarboxylic acid, and zinc and / or alkaline earth metal charged is maleic acid and / or maleic anhydride: oxycarboxylic acid: zinc and / or alkali. Earth metal = 0.2 to 10: 1: 0.1 to 5 and zinc and /
Alternatively, it is preferable that the molar amount of the alkaline earth metal does not exceed the total molar amount of maleic acid and / or maleic anhydride and oxycarboxylic acid.

Then the aqueous mixture is concentrated. Concentration is preferably carried out under reduced pressure, preferably at 20 to 120 ° C., more preferably at 40 to 90 ° C. for about 0.5 to 48 hours. As to the degree of concentration, as described above, in the addition reaction of maleic acid and oxycarboxylic acid, the higher the concentration of these organic acid salts, the higher the equilibrium arrival yield of the ethercarboxylic acid metal salt formation reaction becomes. It is necessary to concentrate to a high concentration that does not hinder stirring, heat removal, etc. Specifically, the alkali metal salt concentration (hereinafter referred to as "organic acid salt concentration") calculated as assuming that all the carboxyl groups of the organic acid in the aqueous mixture are alkali metal salts is 20% by weight or more, preferably Is preferably performed up to 45% by weight or more.

After concentration, add alkali metal and adjust the base equivalent / acid equivalent to 1.
The reaction is carried out within the range of 05 to 2.0, preferably 1.10 to 1.50. When the base equivalent / acid equivalent is less than 1.05, the addition reaction between maleic acid and oxycarboxylic acid does not proceed,
On the other hand, when the base equivalent / acid equivalent is greater than 2.0, as described above, the decomposition of the produced ether carboxylic acid metal salt into oxycarboxylic acid and unsaturated acid (maleic acid and fumaric acid) increases, and the by-product fumaric acid is generated. As the amount increases, the purity and yield of the metal salt of ether carboxylic acid decrease.

As the alkali metal to be added, as described above, sodium, potassium and the like can be mentioned as an example, and preferably used as a hydroxide such as sodium hydroxide or potassium hydroxide.

During the addition reaction, the viscosity of the liquid decreases as the reaction progresses, and stirring becomes easier. Therefore, it is preferable to increase the equilibrium arrival yield of the metal ethercarboxylic acid salt by performing concentration while the reaction. The reaction temperature is preferably 20 to 120 ° C, more preferably 40 to 90 ° C, and the reaction time is suitably 0.5 to 20 hours.

Thus, the ether carboxylic acid metal salt which is the object of the present invention is produced. Further after this, an inorganic acid (for example, hydrochloric acid,
Sulfuric acid, carbonic acid, etc.) or organic acid (eg, oxalic acid, acetic acid, tartaric acid, etc.) is added, or the reaction mixture is diluted with water and then cooled to cool unreacted oxycarboxylic acid metal salt (alkali metal salt, alkaline earth metal). It is preferable to precipitate and separate (including metal salts and zinc salts) because the purity of the product can be increased.

Here, the obtained metal salt of ether carboxylic acid is a mixed salt of alkali metal and zinc or alkaline earth metal. Any metal salt is used as a chelating agent for the purpose of capturing heavy metals. However, what is useful as a detergent builder is an ether carboxylic acid alkali metal salt,
Zinc ether carboxylic acid salts or alkaline earth metal salts are not useful. Therefore, by contacting these mixed salts with carbonates and / or bicarbonates of alkali metals to precipitate zinc and alkaline earth metals as carbonates and removing them, alkali metal ether carboxylates useful for detergent builders, etc. The salt is produced in high purity. As described above, the zinc carbonate or the alkaline earth metal carbonate discharged here also contains the alkali metal salt of ether carboxylic acid, the zinc salt or the alkaline earth metal salt. In the method of the present invention, zinc or alkaline earth metal is recovered and reused as described below to improve the yield of the alkali metal ethercarboxylic acid salt and significantly reduce waste.

Next, this method will be described in detail. The reaction product containing various metal salts of ethercarboxylic acid obtained as described above is contacted with an alkali metal carbonate or bicarbonate to remove the precipitated zinc carbonate or alkaline earth metal carbonate. A mixture obtained by recovering the removed zinc carbonate or alkaline earth metal carbonate while obtaining an alkali metal salt of ether carboxylic acid and reacting the recovered carbonate with maleic acid and / or maleic anhydride in an aqueous medium Is reused as the first addition reaction raw material.

First, a reaction product containing various metal salts of ethercarboxylic acid and an alkali metal carbonate or bicarbonate are usually contacted at 60 to 100 ° C to remove precipitated zinc carbonate or alkaline earth metal carbonate. To obtain an ether carboxylic acid alkali metal salt. The reaction product is preferably treated in advance as described above to separate and remove unreacted oxycarboxylic acid. As the alkali metal, as described above, sodium, potassium and the like can be mentioned as examples. The contact is carried out by adding a carbonate and / or bicarbonate of an alkali metal while stirring a reaction product containing various metal salts of ether carboxylic acid, or conversely, a carbonate and / or bicarbonate of an alkali metal. You may add the reaction product containing various metal salts of ethercarboxylic acid, stirring an aqueous solution containing a salt. By bringing them into contact, zinc or alkaline earth metal in the reaction product containing various metal salts of ethercarboxylic acid is precipitated as carbonate, and ethercarboxylic acid exists as an alkali metal salt in the aqueous liquid. . The deposited zinc carbonate or alkaline earth metal carbonate is separated and removed by a decanter, a filter or the like to obtain an alkali metal ethercarboxylic acid salt as an aqueous liquid.

The removed zinc carbonate or alkaline earth metal carbonate may be recovered, and the recovered carbonate may be reacted with maleic acid and / or maleic anhydride in an aqueous medium for recycling. As the reaction conditions, it is preferable to heat at room temperature or higher, preferably 50 to 90 ° C., and maintain at pH 7 or lower at low viscosity for several hours. Further, it is preferable that the stirring is performed sufficiently so that the carbonate particles can be diffused. It is also possible to absorb the carbon dioxide gas generated by this reaction in an aqueous solution of an alkali metal hydroxide or the like and recover it, and use it as a raw material for the above-mentioned alkali metal carbonate and / or bicarbonate. Thus, the recovered carbonate generates carbon dioxide gas to become a zinc or alkaline earth metal salt of maleic acid, and is reused in the first step as a raw material for the addition reaction. Thus, in the present invention, zinc and alkaline earth metals are recovered using maleic acid and / or maleic anhydride, which are raw materials for addition reaction, so that a large amount of useful substances are not discarded, and therefore environmental pollution is also prevented. it can. In addition, various metal salts of ethercarboxylic acid discharged along with the slurry of zinc carbonate or alkaline earth metal carbonate are also circulated in the first step together with zinc or alkaline earth metal salt of maleic acid by such an operation. , Can be effectively recovered with almost no deterioration.

[Examples] Hereinafter, the method of the present invention will be described in more detail with reference to Examples.

Example 1 DL-disodium tartrate 28% by weight aqueous solution 34 in a 500-liter reaction kettle
Charge 6kg (500mol), then maleic anhydride 46.6Kg
(475 mol) were added, and further, 83.4 kg (450 mol) of 40 wt% calcium hydroxide slurry and 4.2 kg (50 mol) of 48 wt% sodium hydroxide aqueous solution were added. Therefore, the base equivalent / acid equivalent of this content is 1.00. The pH at this time is
The organic acid salt concentration was 8.7, and the result of analysis by high performance liquid chromatography was 36.0% by weight.

The resulting slurry was concentrated under reduced pressure at 70 ° C. to 279.0 kg. The time required for concentration was about 3 hours. Further, 22.8 kg (273 mol) of 48% by weight sodium hydroxide aqueous solution was added to adjust the base equivalent / acid equivalent to 1.14, and then the reaction was carried out while concentrating at 75 ° C. for 8 hours. The organic acid salt concentration after the reaction was 61.6% by weight.

In order to separate the unreacted tartaric acid from the reaction product, 103.4 kg of water and 3.8 kg (25 mol) of DL-tartaric acid were added to the reaction solution, stirred, and allowed to stand at 30 ° C for 24 hours, and the precipitated calcium tartrate was filtered off. (Note that this calcium tartrate was used in the following Example 2), and a filtrate was obtained.

In another 500-liter reaction kettle, water 99.1 kg, sodium carbonate 14.1 kg (13
3 mol) and 24.4 kg (291 mol) of sodium bicarbonate were charged and heated to 60 ° C., and the above filtrate was heated to 60 ° C. and gradually added dropwise for about 2 hours. After the dropping was completed, the mixture was aged at 80 ° C. for about 3 hours, and the precipitated calcium carbonate was filtered off (this calcium carbonate was used in the following Example 2). Monosuccinic acid tartaric acid sodium salt (hereinafter referred to as TMS) and disuccinic acid tartaric acid sodium salt (hereinafter referred to as TD) in the obtained filtrate.
The purity of the mixture (referred to as S) was 88.4% by weight (vs total organic acid sodium salt). The composition of the organic acid salt in the filtrate is shown in Table 1.

Example 2 43.6 kg of calcium carbonate filtered off in Example 1 in a 500 l reactor
(305 mol: 4.2 kg of organic acid sodium salt) and water
Charge 78.4 kg and heat to 80 ° C, then add maleic anhydride 4
6.6 kg (475 mol) was gradually added dropwise in about 2 hours. Calcium tartrate obtained in Example 1 after aging at 80 ° C. for 3 hours 5
Add 1.9 kg (120 mol: 8.8 kg of organic acid sodium salt) and 23.3 kg of water, and further add 263.3 kg (380 mol) of DL-disodium tartrate 28% by weight aqueous solution and calcium hydroxide.
4.6 kg (25 mol) of a 40 wt% slurry was added. Further, 48 wt% sodium hydroxide aqueous solution was added to adjust the content of base equivalent / acid equivalent to 1.01. At this time, the pH was 9.8, and the organic acid salt concentration was 35.8% by weight as a result of analysis using high performance liquid chromatography.

The obtained slurry was concentrated under reduced pressure at 70 ° C for about 3 hours to 300 kg, and further 48% by weight sodium hydroxide aqueous solution 22.8 kg.
(273 mol) was added to adjust the base equivalent / acid equivalent to 1.14, and then the reaction was carried out while concentrating at 75 ° C. for 8 hours. Thereafter, the same operation as in Example 1 was performed, and the results shown in Table 1 were obtained.

Example 3 A flask was charged with 380 g of water, 150 g (1.0 mol) of DL-tartaric acid and 93 g (0.95 mol) of maleic anhydride, then 167 g (0.9 mol) of 40 wt% calcium hydroxide slurry and 48 wt% sodium hydroxide. Aqueous solution 165g (1.983mol)
Was added to prepare a slurry having a base equivalent / acid equivalent of 0.97 and an organic acid salt concentration of about 36% by weight. The slurry was concentrated at 70 ° C. for 3 hours to 558 g, then the base equivalent / acid equivalent was 1.
55 g of 48% by weight sodium hydroxide aqueous solution so as to be 14
(0.663 mol) was added, and the reaction was carried out while further concentrating at 75 ° C. for 8 hours. The organic acid salt concentration after the reaction was 60.5% by weight. Thereafter, the same operation as in Example 1 was performed, and the results shown in Table 1 were obtained.

Comparative Examples 1 to 3 In Example 3, the base equivalent / acid equivalent before concentration was changed, and the reaction was analyzed by high performance liquid chromatography until the reaction reached equilibrium and the total yield of TMS and TDS reached the maximum. The same operations as in Example 3 were carried out except for the above, and the results shown in Table 1 were obtained.

Example 4 In the raw material charging, the amount of the 48 wt% sodium hydroxide aqueous solution was increased to set the base equivalent / acid equivalent to 1.03, and after concentration
The same operation as in Example 3 was conducted except that the amount of the 48 wt% sodium hydroxide aqueous solution was also increased to set the base equivalent / acid equivalent to 1.20, and the results shown in Table 1 were obtained.

Example 5 A 2 liter flask was charged with 1100 g of water, 134 g (1.0 mol) of malic acid and 118 g (1.2 mol) of maleic anhydride, then 185 g (1.0 mol) and 40 of a 40% by weight calcium hydroxide slurry.
Add 203 g (2.44 mol) of aqueous solution of sodium hydroxide by weight, base equivalent / acid equivalent is 1.01, organic acid salt concentration is about 21% by weight.
Was prepared. This slurry was concentrated to about 700 g over 4 hours at 70 ° C (organic acid salt concentration about 53% by weight), and then 33 g (0.40 mol) of 48% by weight aqueous sodium hydroxide solution so that the base equivalent / acid equivalent was 1.10. And then add 75
The reaction was carried out while concentrating at 5 ° C for 5 hours. The organic acid salt concentration after the reaction was 55% by weight.

By a method similar to that in Example 1, sodium carbonate and sodium bicarbonate were added to precipitate calcium in the reaction mixture as calcium carbonate and then separated to obtain a filtrate containing tetrasodium oxydisuccinate. The purity of tetrasodium oxydi-succinate in the filtrate was 71% by weight (vs. total organic acid sodium salt).

Comparative Example 4 In Example 5, the 48 wt% sodium hydroxide aqueous solution was not added stepwise, and 236 g (2.84 g
Molar: Therefore, the base equivalent / acid equivalent at the time of charging was added 1.10), and the reaction was carried out while concentrating over 8 hours so that the concentration of the organic acid salt after the reaction finally became about 55% by weight. 5
It carried out similarly to. The purity of the obtained tetrasodium oxydi-succinate was 65% by weight (based on the total organic acid sodium salt).

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Akio Fukui, Inventor Akio Fukui, 992, Okihama, Aki-ku, Himeji-shi, Hyogo Prefecture, Himeji Research Laboratories, Nippon Catalytic Chemical Industry Co., Ltd. No. 1 Shuji Sasaki, Examiner, Himeji Laboratory, Nippon Catalysis Chemical Co., Ltd.

Claims (9)

[Claims] 1. A maleic acid and / or maleic anhydride, (b) an oxycarboxylic acid, (c) an alkali metal, (d) zinc and / or an alkaline earth metal, and (b) a maleic acid and The ratio of the total base equivalent of (c) alkali metal and (d) zinc and / or alkaline earth metal to the total acid equivalent of maleic anhydride and (b) oxycarboxylic acid is within the range of 0.93 to 1.04. Preparation of an ether carboxylic acid metal salt characterized by concentrating an aqueous mixture, and then adding an alkali metal to adjust the above equivalent ratio to a range of 1.05 to 2.0 to carry out an addition reaction of maleic acid and oxycarboxylic acid. Method. 2. The molar ratio of (a) maleic acid and / or maleic anhydride, (b) oxycarboxylic acid, (d) zinc and / or alkaline earth metal in the aqueous mixture is 0.2.
-10: 10: 0.1-5, and the molar amount of (d) zinc and / or alkaline earth metal exceeds the total molar amount of (b) maleic acid and / or maleic anhydride and (b) oxycarboxylic acid. The manufacturing method according to claim 1, wherein the manufacturing is performed so as not to exist. 3. The production method according to claim 1, wherein after completion of the addition reaction, an organic acid or an inorganic acid or water is added to precipitate and separate unreacted oxycarboxylic acid as a metal salt. 4. A reaction product containing an ether carboxylic acid metal salt obtained by the method according to claim 1 is contacted with an alkali metal carbonate and / or an alkali metal bicarbonate to give zinc carbonate and / or The production method according to claim 1, wherein the alkaline earth metal carbonate is deposited and separated. 5. Zinc maleate and / or maleic acid obtained by contacting zinc carbonate and / or alkaline earth metal carbonate separated in claim 4 with maleic acid and / or maleic anhydride in an aqueous medium. The production method according to claim 1, wherein an alkaline earth metal salt is formed and is reused as a raw material for producing an ethercarboxylic acid metal salt. 6. The method according to claim 1, wherein the oxycarboxylic acid is tartaric acid. 7. The concentration of the aqueous mixture is such that the concentration of the alkali metal salt is 45% by weight or more when calculated assuming that all the carboxyl groups of maleic acid and oxycarboxylic acid are alkali metal salts in the aqueous mixture. The manufacturing method according to claim 6, wherein the manufacturing method is carried out until the above. 8. The method according to claim 6, wherein the ether carboxylic acid is tartaric acid monosuccinate and / or tartaric acid disuccinate. 9. The method according to claim 1, wherein the metal salt of ethercarboxylic acid is an alkali metal salt of ethercarboxylic acid.