JP2003306695A - Method for producing weakly acidic transparent solid detergent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably producing a weakly acidic transparent solid detergent in high quality at a low cost by using an N-acyl acidic aminocarboxylic acid as a base while preventing the solidification of the base. <P>SOLUTION: The transparent solid detergent containing the N-acyl acidic aminocarboxylic acid, a polyhydric alcohol, a lower alcohol, a neutralizing agent and water is produced by condensing an acidic aminodicarboxylic acid with a long-chain fatty acid halide, adjusting the pH of the produced condensation reaction liquid to ≤5, washing the formed organic phase component with an aqueous solution of a lower alcohol/sulfuric acid, dehydrating and concentrating the obtained organic phase component to a concentration of 40-90 mass% without solidifying the component and using the product as a base. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a weakly acidic transparent solid detergent. More specifically, the present invention is based on an N-long chain acyl acidic amino carboxylic acid having an acidic amino carboxylic acid residue having one amino group or imino group and two carboxylic acid groups as a hydrophilic group. The present invention relates to a method for producing a weakly acidic transparent solid detergent contained as.

[0002]

Conventionally, a fatty acid soap has been used as a main component in a transparent solid detergent, but the fatty acid soap is composed of a lower fatty acid component blended for the purpose of improving solubility, foaming and detergency. Also, the skin may be irritated by free alkali in the fatty acid soap and by the increase in pH due to hydrolysis of the fatty acid soap during use. As a method for solving these drawbacks, a transparent solid detergent based on an N-acyl acidic amino acid salt having surface activity even in a weak acidic region has been proposed.

The compounding composition of a transparent solid detergent based on an N-acyl acidic amino acid salt is described in JP-A-55-25465, JP-A-4-1297 and JP-A-6-264092.
It is known from the newsletter. N-long chain acyl acidic amino acids used as a raw material for transparent solid detergents based on these N-acyl acidic amino acid salts are disclosed in JP-B-46-8.
No. 685 report, obtained by a condensation reaction of a fatty acid halide and an acidic amino acid, containing or not containing an organic solvent, containing an inorganic salt such as sodium chloride as a by-product, N-acyl acidic amino acid The salt content is 20 to 3
It is manufactured as a 0% aqueous solution. When the reaction conditions are changed so that the content of the produced N-acyl acidic amino acid salt in the reaction mixture obtained at this time is 30% or more,
Such reaction conditions are not generally adopted because the amount of residual unreacted material increases and gelation occurs to make the reaction difficult.

On the other hand, in the case of producing a transparent solid detergent based on an N-acyl acidic amino acid salt, it depends on the kind of the N-acyl acidic amino acid salt used as the starting material, but in the composition, N- Acyl acidic amino acid salt 30
%, It is difficult to use as a raw material an aqueous solution having an N-acyl acidic amino acid salt content of 20 to 30%. In addition, since inorganic salts such as sodium chloride produced as a by-product in the reaction solution impair the transparent stability of the target weakly acidic transparent solid detergent, the N-long-chain acyl produced by known techniques is generally used. It was usual to desalt the acidic amino acid salt solution, solidify the N-acyl acidic amino acid by a method such as recrystallization or spray drying, and use this as a raw material.

However, since a plurality of manufacturing apparatuses are required in order to carry out a drying step such as filtration separation of crystals and a vacuum heating in the manufacturing step, if this is done, the economical efficiency is remarkably lowered and the heating in each step is performed. However, there is a drawback such as deterioration of quality due to coloring or / and deterioration of odor, which makes it difficult to inexpensively and stably produce a weakly acidic transparent solid detergent containing an N-long-chain acyl acidic amino acid. there were.

In the case of isolating and solidifying N-acyl acidic aminocarboxylic acid, depending on the selection of the acyl group source and the acidic aminocarboxylic acid, it is possible to use a manufacturing method such as spray drying or recrystallization which has a relatively small thermal history. In some cases, it is difficult to pulverize the powder. Therefore, it is difficult to change the physical properties of the transparent solid detergent by freely blending the composition of the N-long-chain acyl acidic aminocarboxylic acid. Therefore, the transparent solid detergent has not been widely used despite its high safety. Therefore, it has been desired to develop a manufacturing method of a cheaper and higher quality transparent solid detergent. .

[0007]

DISCLOSURE OF THE INVENTION In the present invention, when a transparent solid detergent is prepared by using N-acyl acidic aminocarboxylic acid as a base, the N-acyl acidic aminocarboxylic acid used as the base is solidified. -Using the purified concentrated solution of the reaction mixture without drying, prevents deterioration of the base quality and cost increase that occur due to its solidification and drying,
An object of the present invention is to provide a method for stably and inexpensively producing a high-quality transparent solid detergent.

[0008]

Means for Solving the Problems As a result of intensive investigations by the present inventors in order to overcome the drawbacks of conventional weakly acidic transparent solid detergents, the production of N-long chain acyl acidic aminocarboxylic acid as a base The color of the weakly acidic transparent solid detergent resulting from the solidification of the N-long-chain acyl acidic aminocarboxylic acid is produced by using the purified concentrated solution of the reaction mixture obtained as described above as a raw material to produce a weakly acidic transparent solid detergent. In addition to the stabilization, it is also possible to manufacture a weak acidic transparent solid detergent containing a low melting point N-acyl acidic aminocarboxylic acid as a main component, which cannot be solidified by the conventional manufacturing method. The present invention has been completed and the present invention has been completed.

That is, the method for producing a weakly acidic transparent solid detergent of the present invention comprises a base comprising N-acyl acidic aminocarboxylic acid, a polyhydric alcohol having 3 to 6 carbon atoms per molecule, and a per molecule. An additive component containing a lower alcohol having 2 to 4 carbon atoms, the N-acyl acidic aminocarboxylic acid neutralizing agent, and water is mixed and heated to dissolve,
The N-acyl acidic aminocarboxylic acid-containing base comprises cooling the melt to solidify it into a desired shape and size, wherein the N-acyl acidic aminocarboxylic acid-containing base has one amino group or imino group and two carboxylic acid groups per molecule. An acidic aminodicarboxylic acid having and 6 to
A long-chain fatty acid halide containing 22 carbon atoms is subjected to a condensation reaction in an alkaline reaction medium to give a hydrophilic group consisting of the acidic aminodicarboxylic acid residue and a hydrophobic group consisting of the long-chain fatty acid halide residue. A N-acyl acidic aminodicarboxylic acid compound consisting of a group is produced, and the pH of the condensation reaction mixture containing this product is adjusted to 5 or less, whereby phase separation occurs in the product-containing condensation reaction mixture. The organic phase component thus formed is collected separately, and the organic phase component is washed with an aqueous solution containing a lower alcohol having 2 to 4 carbon atoms and sulfuric acid. As an aqueous liquid obtained by separating and collecting, dehydrating and concentrating the organic phase component without solidifying, and containing 40 to 90% by mass of N-acyl acidic aminocarboxylic acid,
It is characterized in that it is subjected to the mixing and heating dissolution step. In the method for producing a weakly acidic transparent solid detergent of the present invention, the lower alcohol used as the detergent component and the lower alcohol used for washing the organic phase component are, independently of each other, ethanol, n-propanol and It is preferably selected from isopropanol. In the method for producing a weakly acidic transparent solid detergent of the present invention, the acidic aminodicarboxylic acid is preferably selected from glutamic acid, iminodiacetic acid, and carboxyethylglycine. The method for producing a weakly acidic transparent solid detergent of the present invention may further include at least one selected from a hydrocarbon having 6 to 12 carbon atoms per molecule, thiourea, urea, and maltitol. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, a weakly acidic transparent solid detergent comprises a base consisting of N-acyl acidic aminocarboxylic acid, a polyhydric alcohol having 3 to 6 carbon atoms per molecule, and a molecule. An additive component containing a lower alcohol having 2 to 4 carbon atoms per unit, the N-acyl acidic aminocarboxylic acid neutralizing agent, and water is mixed and heated to dissolve,
It is obtained by cooling this melt and solidifying it to the desired shape and size.

In the method of the present invention, in the production of a substrate containing an N-acyl acidic aminocarboxylic acid, first, an acidic aminodicarboxylic acid having one amino group or imino group and two carboxylic acid groups per molecule. And a long-chain fatty acid halide containing 6 to 22 carbon atoms are subjected to a condensation reaction in an alkaline reaction medium to give a hydrophilic group consisting of the acidic aminodicarboxylic acid residue and the long-chain fatty acid halide residue. And an N-acyl acidic aminodicarboxylic acid compound consisting of a hydrophobic group consisting of

The fatty acid halide which can be used in the method of the present invention is an acyl group having 6 to 22 carbon atoms, preferably 8 to 20 carbon atoms, which is derived from a saturated or unsaturated fatty acid, such as lauric acid, myristic acid, palmitic acid, It can be selected from fatty acid halides of a single fatty acid containing an acyl group such as stearic acid and oleic acid, mixed fatty acid halides derived from mixed fatty acids such as coconut oil fatty acid, palm kernel oil fatty acid, palm fatty acid and tallow fatty acid. As described above, when a conventional N-acyl acidic aminocarboxylic acid is isolated as a solid and used as a base of a transparent solid detergent, depending on the kind of the raw material fatty acid halide, recrystallization, spray drying, or the like may be performed. In some cases, solidification may be difficult under conditions where the heat history during production is relatively mild, but in the method of the present invention, the reaction product is not isolated as a solid, so there are no restrictions on the selection of raw materials. It has the excellent advantage of

The acidic aminodicarboxylic acid in the present invention has one amino group or imino group and two carboxylic acid groups per molecule, and may be a natural product or a synthetic product. Glutamic acid, iminodiacetic acid, carboxyethylglycine and the like are preferably used.

For the preparation of the N-acyl acidic aminocarboxylic acid salt which is the base of the weakly acidic transparent solid detergent, the pH of an aqueous solvent containing a lower alcohol having 2 to 4 carbon atoms is used.
Is prepared to 10 to 13 using an aqueous solution of an alkali agent such as an alkali metal hydroxide, and an acidic aminocarboxylic acid is added thereto to have a concentration of 20 to 60%, preferably 30 to 50%.
An acidic aminocarboxylic acid aqueous solution is prepared. In this aqueous solution, a fatty acid halide was added with an alkali to pH 10-13.
The condensation reaction is carried out by adding dropwise at 30 ° C. or lower while adjusting so as to fall within the range. The ratio of lower alcohol to water used in the above reaction is 5:95 to 80:20.
And preferably 20:80 to 50:50. At this time, when the content of the lower alcohol is 5:95 or less, the content of the fatty acid salt as a by-product is increased, and the content is 50:50.
In the above cases, the ester with lower alcohol increases, and these by-products may hinder the formulation of the weakly acidic transparent solid detergent.

There is no particular difficulty in converting the N-long-chain acyl acidic aminocarboxylic acid salt obtained by the above condensation reaction into the N-long-chain acyl acidic aminocarboxylic acid, and the pH is adjusted to 5 with a mineral acid such as sulfuric acid or hydrochloric acid. Hereafter, it may be preferably 2 or less.
That is, the pH may be adjusted to 5 or lower by adding a mineral acid to an aqueous solution containing an N-long chain acyl acidic aminocarboxylic acid salt while stirring. The reaction mixture containing the N-long-chain acyl acidic aminocarboxylic acid oxidation product is mixed with an organic phase containing N-long-chain acyl acidic aminocarboxylic acid and water by adjusting pH with a mineral acid or by heating after adjusting the pH. Separate into phases. This separation temperature condition may be a temperature at which the N-long chain acylaminocarboxylic acid is melted, but is usually from room temperature to the boiling point of the lower alcohol. When the boiling point of the lower alcohol is exceeded, it is necessary to separate the layer under pressure, which requires a large amount of equipment cost, which is economically disadvantageous. The state in which the N-long-chain acylaminocarboxylic acid is melted means the state in which the reaction liquid mixture is fluid and is liquefied. If the mixture of the melt and water is allowed to stand, these can be easily separated.

The organic phase component obtained by the method of the present invention is
It includes an inorganic salt produced as a by-product during the preparation of the N-long chain acyl acidic aminocarboxylic acid salt. This inorganic salt precipitates on the surface of the transparent solid detergent over time after formulation and impairs its commercial value, so in the method of the present invention, this organic phase component is washed with an aqueous solution containing a lower alcohol and sulfuric acid. By doing so, the inorganic salt can be removed. At this time, the ratio of the lower alcohol to the 1% sulfuric acid water is set to 5:95 to 40:60, preferably, the inorganic salt is easily removed by washing with an aqueous solution in the ratio of 10:90 to 20:80. You can When the ratio of the lower alcohol to the 1% sulfuric acid water is 5:95 or less, the aqueous phase becomes the upper layer, and separate equipment is required to completely separate the organic phase containing the N-long-chain acyl acidic aminocarboxylic acid. , May be economically disadvantageous. When an acid other than sulfuric acid is used in this cleaning liquid, the aqueous phase may be the upper layer. When the ratio of the lower alcohol to the 1% sulfuric acid water is 40:60 or more, the N-long chain acyl acidic aminocarboxylic acid may be dissolved in the washing liquid, which may make the layer separation difficult.

The organic phase component obtained by the method of the present invention is
It is a mixed melt of N-long-chain acyl acidic aminocarboxylic acid containing water and lower alcohol, but the content of N-long-chain acyl acidic aminocarboxylic acid may be less than 40% by weight depending on the selection of reaction conditions. Therefore, the organic phase component is dealcoholated and dehydrated. Since the N-long-chain acyl acidic aminocarboxylic acid is an acid type, the depressurizing operation in this treatment can be performed smoothly without foaming. Further, since the lower alcohol is added as an essential component even when it is made into a transparent solid detergent, it is not necessary to completely distill them off, and it may be concentrated under ordinary heating and reduced pressure to an extent necessary for formulation. That is, the N-long chain acyl acidic aminocarboxylic acid content is 40 to 90% by weight,
Dealcoholize, dehydrate and concentrate. N obtained at this time
Since the long-chain acyl acidic aminocarboxylic acid-containing material contains water and a trace amount of a lower alcohol, it has a low melting temperature as compared with a highly pure N-long chain acidic acidic aminocarboxylic acid. Therefore, it is also possible to store the N-long chain acyl acidic aminocarboxylic acid-containing material, separately heat-dissolve it, and use it as a raw material for a transparent solid detergent.

The concentration can be easily known by measuring the content of the N-long chain acyl acidic aminocarboxylic acid by high performance liquid chromatography. At this time, N of the organic layer
-When the content of long-chain acyl acidic aminocarboxylic acid is less than 40% by weight, the weakly acidic transparent solid detergent produced is insufficient in hardness and easily deformed, and when it exceeds 90% by weight, it is concentrated. However, the viscosity is increased and it becomes difficult to mix other components, and it may not be possible to obtain a weakly acidic transparent solid detergent, which is not preferable. Concentration is preferably carried out when the content of the N-long chain acyl acidic aminocarboxylic acid is 60 to 70% by weight because the produced weakly acidic transparent solid detergent is hard and has good operability.

In the method of the present invention, examples of the polyhydric alcohol having 2 to 6 carbon atoms to be incorporated into the N-acyl acidic aminocarboxylic acid base include glycerin, sorbitol, and propylene glycol, and these are selected. You may use the mixture of at least 1 type or more mentioned.

Preferred examples of the neutralizing agent for N-long chain acyl acidic aminocarboxylic acid used in the present invention include basic compounds of alkali metals such as sodium, potassium and lithium, monoethanolamine, diethanolamine and triethanol. Basic organic amine compounds such as amines, ammonia and basic amino acid compounds such as arginine, lysine and ornithine are used, and these may be used alone or as a mixture of two or more kinds. In particular, when triethanolamine is used, a product having excellent transparency can be obtained.

In the method of the present invention, the lower alcohol used for cleaning and the lower alcohol contained in the cleaning agent each independently have 2 to 4 carbon atoms, and preferably, generally Lower alcohols used in cosmetics such as ethanol, n-propanol, isopropanol are used.

The optimum embodiment of the method of the present invention is N-
Using the reactor that produced a concentrated aqueous solution containing an acyl acidic aminocarboxylic acid, the concentrated aqueous solution contains other components necessary for preparing a weakly acidic transparent solid detergent: 2 to 6 carbon atoms Polyhydric alcohol, lower alcohol, water for neutralizing N-long-chain acyl acidic aminocarboxylic acid, water, and other additives are added and dissolved by heating, and then poured into a molding container, cooled and solidified, dried, and stamped. The form of producing a weakly acidic transparent solid detergent having a desired shape can be mentioned. At this time, the N-acyl acidic aminocarboxylic acid can be used as it is as a concentrated aqueous liquid without being solidified, so that the cost effect is remarkably high.

The transparent solid detergent of the present invention contains other components usually used in cosmetics for the purpose of adjusting the cleansing property and feeling of use, such as extracts derived from animals, plants, fish and shellfish, microorganisms, powders. Ingredients, liquid oils, solid oils, waxes, hydrocarbons,
Higher fatty acid, higher alcohol, ester, silicone, anionic surfactant other than N-acyl acidic amino acid type, cationic surfactant, amphoteric surfactant, nonionic surfactant, humectant, water-soluble polymer, thickening Agents, coating agents, ultraviolet absorbers, anti-inflammatory agents, sequestering agents, sugars, amino acids,
Organic amines, synthetic resin emulsions, pH adjusters, skin nutrients, vitamins, antioxidants, antioxidant aids, fragrances, water, etc., if necessary, one or two or more, which does not hinder transparent solidification. It is possible to add in a range. These can be used in an amount of 25% by mass or less based on the mass of the transparent solid detergent.

[0024]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Example 1 90.0 g of L-glutamic acid was dissolved in 150.0 g of a 20% aqueous solution of isopropanol, and 40.0 g of a 48% sodium hydroxide aqueous solution was added to this to prepare an L-glutamine sodium aqueous solution. While keeping this at 10 to 20 ° C or lower, add 90.0 g of coconut oil fatty acid chloride and 4
8% sodium hydroxide was simultaneously added dropwise while adjusting the pH to 10-14. After the dropping was completed, the mixture was further stirred at the above temperature for 1 hour to obtain 420.0 g of an aqueous sodium N-coconut oil fatty acid acyl-L-glutamate solution. 75 at 60 ° C
% Sulfuric acid aqueous solution was added to adjust the pH to 1.0, and this was allowed to stand at a temperature of 60 ° C. for 30 minutes, whereby an organic layer and an aqueous layer were separated. The separated organic phase component was washed at the above temperature with a mixed solution of 50.0 g of isopropanol and 400.0 g of 1% sulfuric acid water, and the obtained organic phase component was treated with water-containing N-
325.4 g of coconut oil fatty acid acyl-L-glutamic acid was collected. Then, this aqueous liquid is concentrated under reduced pressure to obtain a water-containing N-
199.0 g of coconut oil fatty acid acyl-L-glutamic acid was obtained. 40.0 g of isopropanol, 102.5 g of triethanolamine, 40.0 g of glycerin, and 40.0 g of urea were added to this, and it heated at 80-85 degreeC, and melt | dissolved uniformly. The melt was poured into a mold, cooled to room temperature and solidified to obtain a transparent solid detergent. The composition of the obtained transparent solid detergent formulation is as shown in Table 1.

[0025]

[Table 1]

Comparative Example 1 N-coconut oil fatty acid acyl-L-glutamic acid powder was prepared so that the final blending ratio of Example 1 was obtained, and a transparent solid detergent was manufactured by a conventional method.

Test In order to compare the conventional method with the method of the present invention, the method of Example 1 and Comparative Example 1 was repeated 5 times to prepare a transparent solid detergent. (1) Appearance Hue is a sample obtained by cutting a transparent solid detergent to a thickness of 10 mm and smoothing the surface.
It was judged by the value measurement. (2) The odor was judged by sensory evaluation by a monitor. Example 1 in each of tests (1) and (2)
The first three samples were evaluated as the following three levels. ○
Table 2 summarizes the evaluation of each sample, which is equivalent to the first sample of Example 1, Δ is slightly worse than the first sample of Example 1, and x is worse than the first sample of Example 1.

[0028]

[Table 2]

In the production experiment of the transparent solid detergent according to the method of the present invention, it was confirmed that no difference in appearance (hue) and odor was observed in all five times, but in the production by the conventional method, the hue, particularly the yellow tint was varied. It was recognized that the b value was not stable and that one of the 5 cases had a slightly different odor depending on the evaluator.

Example 2 58.1 g of iminodiacetic acid was dissolved in 205.8 g of a 30% aqueous solution of isopropanol, and 71.3 g of a 48% sodium hydroxide aqueous solution was added thereto to prepare a sodium iminodiacetic acid solution. Next, while maintaining this at 20 to 30 ° C. or lower, 90.0 g of lauric acid chloride and 48% sodium hydroxide were simultaneously added dropwise thereto while adjusting the pH to 10 to 14. After completion of the dropping, the mixture is further stirred at the above temperature for 1 hour to prepare an aqueous solution of sodium N-lauroyl iluminodiacetate 45
8.3 g was obtained. A 75% sulfuric acid aqueous solution was added at 60 ° C. to adjust the pH to 1, and this was allowed to stand at a temperature of 60 ° C. for 30 minutes, whereby an organic layer and an aqueous layer were separated. The separated organic phase component was washed with a mixed solution of 50.0 g of isopropanol and 400.0 g of 1% sulfuric acid water at a temperature of 60 ° C.
311.3 g of lauroyl iminodiacetic acid were collected. Next, this was concentrated under reduced pressure to obtain 205.1 g of water-containing N-lauroyl uiminodiacetic acid. Isopropanol 1
8.1 g, triethanolamine 104.7 g, glycerin 36.1 g, and urea 18.1 g were added, and the temperature was 80 to 85 ° C.
After being heated to 0 and melted uniformly, it was poured into a mold and cooled and solidified at room temperature to prepare a transparent solid detergent. The compounding composition of the obtained transparent solid detergent is shown in Table 3.

[0031]

[Table 3]

The method of Example 2 was repeated 5 times to prepare a transparent solid material. A product having excellent transparency and no difference in appearance (hue) and odor was obtained after all 5 times.

[0033]

Industrial Applicability According to the method of the present invention, a weakly acidic transparent solid detergent having excellent quality can be produced stably and at low cost without deterioration of quality.

Continued front page    F-term (reference) 4C083 AB051 AC011 AC101 AC102                       AC111 AC122 AC131 AC661                       AC662 AC681 AC682 AC761                       CC23 DD01 DD21 FF01 FF06                 4H003 AB09 BA01 DA02 EB02 EB04                       EB05 EB18 EB21 FA02 FA10                       FA28

Claims (4)

[Claims] 1. A base comprising an N-acyl acidic aminocarboxylic acid, a polyhydric alcohol having 2 to 6 carbon atoms per molecule, a lower alcohol having 2 to 4 carbon atoms per molecule, and Heating and dissolving a mixture containing an N-acyl acidic aminocarboxylic acid neutralizing agent and water, and cooling the dissolved material to solidify it into a desired shape and size. The carboxylic acid-containing base comprises an acidic aminodicarboxylic acid having one amino group or imino group and two carboxylic acid groups per molecule, and a long-chain fatty acid halide containing 6 to 22 carbon atoms, In an alkaline reaction medium, a condensation reaction is performed to form an N-acyl acidic aminodicarbohydrate comprising a hydrophilic group composed of the acidic aminodicarboxylic acid residue and a hydrophobic group composed of the long chain fatty acid halide residue. An acid compound is produced, and the pH of the condensation reaction mixture containing the product is adjusted to 5 or less, whereby the organic phase component formed by phase separation in the product-containing condensation reaction mixture is separated and collected. Collect the organic phase components from 2 to
It is obtained by washing with an aqueous solution containing a lower alcohol having 4 carbon atoms and sulfuric acid, separating and collecting the organic phase component of this washing mixture, and dehydrating and concentrating the organic phase component without solidifying. And a 40 to 90% by mass of an N-acyl acidic aminocarboxylic acid as an aqueous liquid, which is subjected to the above-mentioned mixing and heating dissolution step. 2. The lower alcohol used as the detergent component and the lower alcohol used for washing the organic phase component are independently ethanol and n-, respectively.
The method for producing a weakly acidic transparent solid detergent according to claim 1, which is selected from propanol and isopropanol. 3. The method for producing a weakly acidic transparent solid detergent according to claim 1, wherein the acidic aminodicarboxylic acid is selected from glutamic acid, iminodiacetic acid, and carboxyethylglycine. 4. The method according to claim 1, further comprising at least one selected from a hydrocarbon having 6 to 12 carbon atoms per molecule, thiourea, urea, and maltitol. 1. A method for producing a weakly acidic transparent solid detergent.