1,3-butylene glycol product and method for producing 1,3-butylene glycol

Abstract

To provide a high-purity 1,3-butylene glycol product that is colorless and odorless and unlikely to cause generation of coloration or odor.SOLUTION: A 1,3-butylene glycol product, wherein at least one of the contents of the following compounds is less than 8 ppm: the content of methyl vinyl ketone, the content of acetone, the content of butyraldehyde, the content of acetaldol, the content of a compound of Formula (1), the content of a compound of Formula (2), the content of a compound of Formula (3), and the total content of a compound of Formula (4) and a compound of Formula (5).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a method for producing 1,3-butylene glycol, and a 1,3-butylene glycol product. This application claims priority to Japanese Patent Application Nos. 2019-239974, 2019-239975, 2019-239976, 2019-239977, 2019-239978, and 2019-239979, filed in Japan on December 28, 2019, Japanese Patent Application No. 2020-006660, filed in Japan on January 20, 2020, and Japanese Patent Application No. 2020-018910, filed in Japan on February 6, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] 1,3-Butylene glycol is a colorless, transparent, odorless liquid with properties such as low volatility, low toxicity, and high hygroscopicity, and has excellent chemical stability. Therefore, its uses are diverse, including as a raw material for various synthetic resins and surfactants, as well as cosmetics, moisture absorbents, high-boiling-point solvents, and antifreeze materials. In recent years, 1,3-butylene glycol has particularly attracted attention for its excellent properties as a moisturizer, and demand for it in the cosmetics industry is expanding.

[0003] 1,3-butylene glycol obtained by conventional manufacturing methods has a problem in that its acid concentration (acidity) increases when stored in an aqueous environment for a long period of time. The cause of this increase in acid concentration was unknown, but it was thought to be related to by-products contained in crude 1,3-butylene glycol. Cosmetics generally contain water, and a long period of time passes between production and actual use by consumers. Furthermore, the liquid properties of cosmetics are strictly controlled to ensure shelf stability. When 1,3-butylene glycol obtained by conventional methods is used in cosmetics, the increase in acid concentration can disrupt the liquid balance of the cosmetics, potentially resulting in a loss of the intended effects. Furthermore, the increase in acid concentration in cosmetics can cause skin irritation and other problems. Even in cosmetics that do not contain water, the acid concentration can increase due to moisture absorption during use or storage. Therefore, there was a need to remove by-products from crude 1,3-butylene glycol and obtain highly purified 1,3-butylene glycol.

[0004] Furthermore, 1,3-butylene glycol obtained by conventional manufacturing methods sometimes has an odor due to the influence of by-products. Even if the product is transparent immediately after production, it may develop coloration over time, posing a problem during long-term storage. For example, cosmetics are exposed to air when used and when stored after use. Furthermore, cosmetics are generally manufactured under an air atmosphere, and may also be heated for sterilization or other purposes. When 1,3-butylene glycol obtained by conventional methods is used in cosmetics, coloration can progress due to the presence of air or the influence of heat. To solve these problems, there has been a need to remove by-products from crude 1,3-butylene glycol and highly purify the resulting 1,3-butylene glycol.

[0005] As a method for obtaining high-purity 1,3-butylene glycol, a method has been proposed in which caustic soda is added to crude 1,3-butylene glycol obtained by hydrogen reduction of acetaldols and the mixture is distilled. Other methods have also been proposed, such as adding an alkali metal base to crude 1,3-butylene glycol from which high-boiling components have been removed, heat-treating the mixture, distilling the 1,3-butylene glycol, separating the alkali metal compounds and high-boiling components as residue, and then distilling the low-boiling components from the 1,3-butylene glycol fraction (Patent Documents 1 to 6). Thus, various methods for purifying 1,3-butylene glycol have been proposed to obtain high-purity 1,3-butylene glycol. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-258129 [Patent Document 2] International Publication No. 00 / 07969 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-213822 [Patent Document 4] Japanese Patent Application Laid-Open No. 2001-213824 [Patent Document 5] Japanese Patent Application Laid-Open No. 2001-213825 [Patent Document 6] Japanese Patent Application Laid-Open No. 2001-213828 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the 1,3-butylene glycol products obtained by these purification methods still contain by-products, and have problems such as an odor, an increase in acid concentration over time when water is added, and discoloration over time.

[0008] 1,3-Butylene glycol can be produced by methods such as (1) reduction (hydrogenation) of acetaldols, (2) hydrolysis of 1,3-butylene oxide, (3) selective hydrogenolysis of erythritol, (4) selective addition of water to butadiene, (5) hydrogenation of n-butanal-3-one, (6) hydrogenation of 1-butanol-3-one, (7) hydrogenation of 3-hydroxy-1-butanoic acid, (8) hydrogenation of β-butyrolactone, and (9) hydrogenation of diketene.

[0009] Among the above production methods, (1) the method of obtaining 1,3-butylene glycol by reduction (hydrogenation) of acetaldols is preferred. Among these, the method of reducing acetaldols in a liquid phase is preferred from the viewpoint of yield. The reasons for this include the fact that acetaldols have a high boiling point, are thermally unstable, and readily undergo dehydration at high temperatures to form crotonaldehyde and the like, and that the dehydration reaction and reduction (hydrogenation) reaction at high temperatures are faster than the reduction reaction. Specifically, when reducing acetaldols in a gas phase, the reaction system must be heated to a high temperature. However, subjecting acetaldols to a high temperature causes dehydration to form crotonaldehyde and the like, and the subsequent reduction reaction produces by-products such as butanol. This results in a relatively low yield of the target 1,3-butylene glycol. Therefore, to obtain a high-purity 1,3-butylene glycol product, liquid-phase reduction is preferred over gas-phase reduction.

[0010] When 1,3-butylene glycol is produced, by-products are generally produced during the production process. For example, when 1,3-butylene glycol is produced by hydrogen reduction of acetaldols, low-boiling substances (low-boiling compounds) having unsaturated bonds, such as acetaldehyde, butylaldehyde, crotonaldehyde, acetone, and methyl vinyl ketone, as well as condensates thereof (e.g., acetaldehyde trimer), hydrogenated products of the condensates, and condensates of 1,3-butylene glycol and the low-boiling substances (e.g., acetal compounds of 1,3-butylene glycol and acetaldol). Other by-products include acetals of crotonaldehyde and 1,3-butylene glycol, acetals of acetaldehyde and 1,3-butylene glycol, and acetals of acetaldol or acetaldehyde and the hydrogenated acetaldehyde trimer. In addition, other by-products include acetic acid contained as an impurity in the raw material acetaldols, and acetic acid used to neutralize the caustic soda used in the production of acetaldols, and a condensation product of 1,3-butylene glycol (an ester of acetic acid and 1,3-butylene glycol). These by-products can have properties of color-causing substances, odor-causing substances, and even acidic substances.

[0011] It is unclear whether the acetal compounds are color-causing substances, odor-causing substances, or acidic substances, and it is conceivable that they possess all of these properties, but they are believed to have strong odor-causing properties. Specifically, although the acetal compounds themselves are unlikely to be odor-causing substances, they may generate odor-causing substances over time or upon heating. Furthermore, the acetal compounds may generate acetaldol upon hydrolysis, which is an odor-causing substance and also has an oxidation (coloring) promoting effect, and therefore can also be considered a color-causing substance. Here, color-causing substances are defined to include not only substances that currently have a color, but also substances that change over time to have a color. Odor-causing substances are defined to include not only substances that currently emit an odor, but also substances that change over time to emit an odor. Acidic substances are defined to include substances whose acid concentration increases over time when they come into contact with water.

[0012] It is not clear whether the ester is a color-causing substance, an odor-causing substance, or an acidic substance, and it is possible that it has all of these properties, but it is believed to have the properties of both an odor-causing substance and an acidic substance strongly, because acetic acid is generated when the ester is hydrolyzed with water.

[0013] In addition, when 1,3-butylene glycol is produced, the by-products in the production process are thought to include a wide variety of by-products that correspond to color-causing substances, odor-causing substances, or acidity-causing substances in addition to the above-mentioned acetal derivatives and ester derivatives. For example, the above-mentioned hydrogenated acetaldehyde trimer is thought to potentially correspond to any of the color-causing substances, odor-causing substances, and acidity-causing substances.

[0014] It is difficult to completely remove the above-mentioned by-products even by using conventional purification methods such as distillation. This is thought to be because new by-products are produced when crude 1,3-butylene glycol is subjected to high-temperature conditions or alkali treatment during the purification stage of crude 1,3-butylene glycol. For these reasons, as mentioned above, the 1,3-butylene glycol products of Patent Documents 1 to 6 contain a wide variety of by-products, and therefore have an odor, become discolored over time, and furthermore, when they contain water, the acid concentration increases over time.

[0015] Therefore, an object of the present disclosure is to provide a high-purity 1,3-butylene glycol product that is colorless and odorless (or almost colorless and odorless), is resistant to coloration and odor generation over time, and is resistant to an increase in acid concentration over time even when containing water. Another object of the present disclosure is to provide a moisturizing agent and a cosmetic that have excellent moisturizing performance and can maintain high quality for a long period of time. Furthermore, another object of the present disclosure is to provide a method for industrially and efficiently producing high-purity 1,3-butylene glycol that is colorless and odorless (or almost colorless and odorless), does not easily become colored over time, and is also unlikely to experience an increase in acid concentration over time even when containing water. [Means for solving the problem]

[0016] The inventors of the present disclosure conducted extensive research to achieve the above-mentioned objectives and found that nine specific compounds, as well as acetaldehyde and crotonaldehyde, are the causative agents of coloration, odor, color increase over time, odor generation over time, and acid concentration increase. They then discovered a method for preventing these compounds from being mixed into 1,3-butylene glycol products. More specifically, they discovered that by adjusting the contents of specific impurities and the 1,3-butylene glycol concentration in the feed liquid of the product column and the high boiling column to fall within specific ranges, and by adjusting the reaction conditions in the reaction step (e.g., the hydrogenation step of acetaldols) (particularly by increasing the hydrogen partial pressure in the reactor), it is possible to obtain colorless and odorless (or nearly colorless and odorless) 1,3-butylene glycol that is resistant to coloration and odor generation over time and resistant to acid concentration increase over time even in a water-containing state. The present disclosure was completed based on these findings and further research.

[0017] That is, the present disclosure provides a 1,3-butylene glycol product in which the content of at least one of the following eight contents is less than 8 ppm: the content of methyl vinyl ketone, the content of acetone, the content of butyraldehyde, the content of acetaldol, the content of the compound represented by the following formula (1), the content of the compound represented by the following formula (2), the content of the compound represented by the following formula (3), and the total content of the compound represented by the following formula (4) and the compound represented by the following formula (5): [ka]

[0018] The 1,3-butylene glycol product may have a total content of methyl vinyl ketone, acetone, butyl aldehyde, acetaldol, the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (3), the compound represented by formula (4), and the compound represented by formula (5) of less than 71 ppm.

[0019] The 1,3-butylene glycol product preferably has an acetaldol content of less than 8 ppm.

[0020] The 1,3-butylene glycol product preferably contains less than 8 ppm of the compound represented by formula (3).

[0021] The 1,3-butylene glycol product preferably has a total content of methyl vinyl ketone, acetone, and butyraldehyde of 24 ppm or less.

[0022] The 1,3-butylene glycol product preferably has a total content of the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (4), and the compound represented by formula (5) of 24 ppm or less.

[0023] The 1,3-butylene glycol product preferably has an acetaldehyde content of less than 4 ppm and a crotonaldehyde content of less than 2 ppm.

[0024] Furthermore, the 1,3-butylene glycol product preferably has an acid concentration (as acetic acid) of less than 11 ppm, and an acid concentration (as acetic acid) of less than 23 ppm after a 90% by weight aqueous solution is kept at 100°C for one week.

[0025] The 1,3-butylene glycol product preferably has an APHA of 6 or less, and an APHA of 78 or less after being kept at 180° C. for 3 hours in an air atmosphere.

[0026] Furthermore, the 1,3-butylene glycol product preferably has an initial boiling point higher than 203°C and / or a dry point of 209°C or lower.

[0027] Furthermore, the 1,3-butylene glycol product preferably has a potassium permanganate test value of 30 minutes or more.

[0028] The present disclosure also provides a moisturizer comprising the 1,3-butylene glycol product.

[0029] The present disclosure further provides a cosmetic comprising the moisturizing agent.

[0030] The present disclosure also provides a method for producing 1,3-butylene glycol, which comprises obtaining purified 1,3-butylene glycol from a reaction crude liquid containing 1,3-butylene glycol, the method comprising the steps of: The process includes a dehydration process for removing water by distillation, a high boiling point removal process for removing high boiling point components by distillation, and a product distillation process for obtaining purified 1,3-butylene glycol. The present invention provides a method for producing 1,3-butylene glycol (hereinafter, may be referred to as "Production Method 1 of the present disclosure"), in which a 1,3-butylene glycol feed solution having an acetaldehyde content of 500 ppm or less, a crotonaldehyde content of 200 ppm or less, a water content of 0.7 wt% or less, and a 1,3-butylene glycol concentration of 97.6 area % or more as determined by gas chromatography analysis under the following conditions is subjected to distillation in a product column used in the product distillation step, at a reflux ratio of 0.3 or more. (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[0031] In the above production method, at least a portion of the distillate from the product column may be recycled to a dehydration step, a dealcoholization step, a low-boiling point removal step, or a step preceding these steps, which are steps preceding the product distillation step.

[0032] The present disclosure also provides a method for producing 1,3-butylene glycol, which comprises obtaining purified 1,3-butylene glycol from a reaction crude liquid containing 1,3-butylene glycol, the method comprising the steps of: The method includes a dehydration step for removing water by distillation and a high boiling point removal step for removing high boiling point components by distillation, Provided is a method for producing 1,3-butylene glycol (hereinafter, may be referred to as "Production Method 2 of the present disclosure"), in which a feed liquid containing 1,3-butylene glycol having an acetaldehyde content of 500 ppm or less, a crotonaldehyde content of 200 ppm or less, a water content of 3 wt% or less, and a 1,3-butylene glycol concentration of 96.7 area% or more as determined by gas chromatography analysis under the following conditions is subjected to distillation at a reflux ratio of 0.03 or more in a high boiling removal tower used in the high boiling removal step. (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[0033] In each of the above production methods, the reaction crude liquid containing 1,3-butylene glycol may be a reaction crude liquid obtained by hydrogen reduction of acetaldols.

[0034] Each of the above production methods may further include at least one step selected from an alkali treatment step of treating a process stream containing 1,3-butylene glycol with a base, a desalting step of removing salts in the process stream containing 1,3-butylene glycol, and a dealcoholization step of removing low boiling points including alcohol in the process stream containing 1,3-butylene glycol.

[0035] In the present disclosure, "1,3-butylene glycol product" refers to a composition in which 1,3-butylene glycol accounts for the majority of the constituent components (for example, the 1,3-butylene glycol content is 95% by weight or more, preferably 98% by weight or more). [Effects of the Invention]

[0036] According to the present disclosure, there is provided a high-purity 1,3-butylene glycol product that is colorless and odorless (or nearly colorless and odorless), does not easily develop coloration or odor over time, and is also not susceptible to an increase in acid concentration over time even when containing water. Furthermore, the present disclosure provides moisturizing agents and cosmetics that have excellent moisturizing performance and can maintain high quality for a long period of time. Furthermore, according to the method for producing 1,3-butylene glycol of the present disclosure, it is possible to industrially and efficiently produce high-purity 1,3-butylene glycol that is colorless and odorless (or almost colorless and odorless), is unlikely to develop coloration or odor over time, and is unlikely to experience an increase in acid concentration over time even when containing water. [Brief explanation of the drawings]

[0037] [Figure 1] 1 is a flowchart of a manufacturing method (purification method) for a 1,3-butylene glycol product of the present disclosure. [Figure 2] 1 is a chart of a gas chromatography analysis of a 1,3-butylene glycol product in Example 1. [Figure 3] 1 is a chart showing the gas chromatography analysis of the 1,3-butylene glycol product in Example 12. [Figure 4] 1 is a chart of a gas chromatography analysis of a 1,3-butylene glycol product in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0038] [1,3-butylene glycol products] The 1,3-butylene glycol product according to the present disclosure has a content of at least one of the following: methyl vinyl ketone content, acetone content, butyl aldehyde content, acetaldol content, content of a compound represented by the following formula (1), content of a compound represented by the following formula (2), content of a compound represented by the following formula (3), and the total content of a compound represented by the following formula (4) and a compound represented by the following formula (5) that is less than 8 ppm. [ka]

[0039] The content of each of the above-mentioned methyl vinyl ketone, acetone, butyl aldehyde, acetaldol, compound represented by formula (1), compound represented by formula (2), compound represented by formula (3), compound represented by formula (4), and compound represented by formula (5) can be quantified by GC-MS analysis under the following conditions. In GC-MS analysis, even very small peaks are subjected to mass spectrometry to quantify each component. Because analysis is performed for specific masses, substances with different masses will not be detected even if other impurities overlap the peak, resulting in higher sensitivity than the GC analysis described below. In this specification, the unit "ppm" for the content of each component in GC-MS analysis means "ppm by weight." (GC-MS analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Ion source temperature: EI 230℃, CI 250℃ Q pole temperature: 150℃ Sample: Ready for analysis

[0040] Under the above analytical conditions, the retention times of the peaks of methyl vinyl ketone, acetone, butyl aldehyde, acetaldol [CHCH(OH)CHCH(=O)], and the compound represented by the following formula (1) are usually shorter than the retention time of the peak of 1,3-butylene glycol. Under the above analytical conditions, the retention time of the peak of 1,3-butylene glycol is usually 5.5 to 7 minutes. Under the above analytical conditions, when the relative retention time of the peak of 1,3-butylene glycol is set to 1.0, the relative retention time of the peak of methyl vinyl ketone is 0.3 to 0.5, the relative retention time of the peak of acetone is 0.3 to 0.5, the relative retention time of the peak of butyl aldehyde is 0.3 to 0.5, the relative retention time of the peak of acetaldol is 0.4 to 0.6, and the relative retention time of the peak of the compound represented by the formula (1) is 0.6 to 0.8. The compound represented by the formula (1) is an acetal compound obtained by reacting acetaldehyde with 1,3-butylene glycol.

[0041] Under the above analytical conditions, the peak retention times of the compound represented by formula (2), the compound represented by formula (3), the compound represented by formula (4), and the compound represented by formula (5) are usually longer than the peak retention time of 1,3-butylene glycol. Under the above analytical conditions, when the relative retention time of the peak of 1,3-butylene glycol is set to 1.0, the relative retention time of the peak of the compound represented by formula (2) is 1.3 to 1.7, the relative retention time of the peak of the compound represented by formula (3) is 1.0 to 1.2, the relative retention time of the peak of the compound represented by formula (4) is 1.6 to 2.0, and the relative retention time of the peak of the compound represented by formula (5) is 1.3 to 1.7. The compound represented by formula (2) is an acetal compound obtained by reacting crotonaldehyde with 1,3-butylene glycol. The compound represented by formula (3) is 1,3-butanediol monoacetate obtained by reacting acetic acid with 1,3-butylene glycol. The compound represented by formula (4) and the compound represented by formula (5) are acetals of acetaldehyde polymers (the compound represented by formula (4) has a hydroxyl group, and the compound represented by formula (5) does not have a hydroxyl group).

[0042] The 1,3-butylene glycol product according to the present disclosure has a content of at least one of eight contents, namely, the content of methyl vinyl ketone, the content of acetone, the content of butyraldehyde, the content of acetaldol, the content of the compound represented by the following formula (1), the content of the compound represented by the following formula (2), the content of the compound represented by the following formula (3), and the total content of the compound represented by the following formula (4) and the compound represented by the following formula (5), of which the content is less than 8 ppm (for example, 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less).Therefore, of the eight contents, one content may be less than 8 ppm (for example, 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less), two contents may be less than 8 ppm (for example, 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less), three contents may be less than 8 ppm (for example, 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less), and four contents may be less than 8 ppm (for example, 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). five of the contents may be less than 8 ppm (e.g., 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less); six of the contents may be less than 8 ppm (e.g., 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less); seven of the contents may be less than 8 ppm (e.g., 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less); or all eight of the contents may be less than 8 ppm (e.g., 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less).

[0043] The 1,3-butylene glycol product preferably has at least four (four, five, six, seven, or eight) of the eight contents of methyl vinyl ketone, acetone, butyraldehyde, acetaldol, the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (3), and the total content of the compound represented by formula (4) and the compound represented by formula (5) below 8 ppm (e.g., 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). In particular, it is preferable that all of the eight contents are below 8 ppm (e.g., 7 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less).

[0044] The 1,3-butylene glycol product may contain the sum of two of the eight contents of the methyl vinyl ketone content, the acetone content, the butyl aldehyde content, the acetone content, the acetone aldol content, the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (3), and the total content of the compound represented by formula (4) and the compound represented by formula (5) (for example, the sum of the methyl vinyl ketone content and the acetone content, the sum of the methyl vinyl ketone content and the acetone content, the sum of the methyl vinyl ketone content and the acetone content, the sum of the methyl vinyl ketone content and the acetone content, the sum of the methyl vinyl ketone content and the compound represented by formula (1), the sum of the methyl vinyl ketone content and the acetone content, the sum of the methyl vinyl ketone content and the compound represented by formula (2)). At least one (e.g., one, two, three, four, ... or all) of the following may be less than 16 ppm (e.g., 15 ppm or less, preferably 14 ppm or less, more preferably 13 ppm or less, even more preferably 12 ppm or less, particularly preferably 11 ppm or less, 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less).

[0045] Furthermore, the 1,3-butylene glycol product contains the sum of three of the eight contents: the methyl vinyl ketone content, the acetone content, the butyl aldehyde content, the acetaldol content, the content of the compound represented by formula (1), the content of the compound represented by formula (2), the content of the compound represented by formula (3), and the total content of the compound represented by formula (4) and the compound represented by formula (5) (for example, the sum of the methyl vinyl ketone content, the acetone content, and the butyl aldehyde content, the methyl vinyl ketone content, the acetaldol content, and the compound represented by formula (1)). At least one (e.g., one, two, three, four, ... or all) of the following may be less than 24 ppm (e.g., 20 ppm or less, preferably 18 ppm or less, more preferably 16 ppm or less, even more preferably 14 ppm or less, particularly preferably 12 ppm or less, 11 ppm or less, 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less).

[0046] The 1,3-butylene glycol product may contain the sum of four of the following contents (for example, the sum of the methyl vinyl ketone content, the acetone content, the butyl aldehyde content, the acetaldol content, the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (3), and the total content of the compound represented by formula (4) and the compound represented by formula (5)) (for example, the sum of the methyl vinyl ketone content, the acetone content, the butyl aldehyde content, and the acetaldol content, or the sum of the acetone content and the butyl aldehyde content). At least one (e.g., one, two, ... or all) of the following may be less than 32 ppm (e.g., the sum of the content of acetaldol, the content of acetaldol, and the content of the compound represented by formula (1)) (e.g., 30 ppm or less, preferably 25 ppm or less, more preferably 20 ppm or less, even more preferably 18 ppm or less, particularly preferably 16 ppm or less, 14 ppm or less, 12 ppm or less, 10 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less).

[0047] Furthermore, the 1,3-butylene glycol product may have a total content of methyl vinyl ketone, acetone, butyraldehyde, acetaldol, compound represented by formula (1), compound represented by formula (2), compound represented by formula (3), compound represented by formula (4), and compound represented by formula (5) that is less than 71 ppm (e.g., 60 ppm or less, preferably 50 ppm or less, more preferably 40 ppm or less, even more preferably 30 ppm or less, particularly preferably 20 ppm or less, 18 ppm or less, 16 ppm or less, 14 ppm or less, 12 ppm or less, 10 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less).

[0048] In addition, the 1,3-butylene glycol product has a total content of impurities that generally have a shorter GC retention time than 1,3-butylene glycol, such as methyl vinyl ketone, acetone, butyl aldehyde, acetaldol, and the compound represented by formula (1), of less than 47 ppm (for example, 40 ppm or less, preferably 30 ppm or less, more preferably 25 ppm or less, even more preferably 20 ppm or less, particularly preferably 18 ppm or less, 16 ppm or less, 14 ppm or less, 12 ppm or less, 10 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). and the total content of the compound represented by formula (2), the compound represented by formula (3), the compound represented by formula (4), and the compound represented by formula (5), which are impurities generally having a longer GC retention time than 1,3-butylene glycol, is preferably less than 24 ppm (for example, 20 ppm or less, preferably 18 ppm or less, more preferably 16 ppm or less, even more preferably 14 ppm or less, particularly preferably 13 ppm or less, 12 ppm or less, 11 ppm or less, 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less).

[0049] Furthermore, the 1,3-butylene glycol product according to the present disclosure preferably has an acetaldol content of less than 8 ppm. Acetaldol generates crotonaldehyde when heated. Crotonaldehyde can be a color-causing substance, an odor-causing substance, or an acidic substance. The acetaldol content is more preferably 7 ppm or less, even more preferably 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less.

[0050] The 1,3-butylene glycol product according to the present disclosure preferably contains less than 8 ppm of the compound represented by formula (3). The compound represented by formula (3) generates acetic acid upon hydrolysis, which causes an acetic acid odor. This also increases the acid concentration (acid content) of the product. The content of the compound represented by formula (3) is more preferably 7 ppm or less, and even more preferably 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less.

[0051] The 1,3-butylene glycol product according to the present disclosure preferably has a total content of methyl vinyl ketone, acetone, and butyraldehyde of 24 ppm or less. These compounds all contain carbonyl groups and may be discoloring, odor, or acidic substances. The total content of methyl vinyl ketone, acetone, and butyraldehyde is more preferably 20 ppm or less, and even more preferably 18 ppm or less, 16 ppm or less, 14 ppm or less, 12 ppm or less, 11 ppm or less, 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less.

[0052] The 1,3-butylene glycol product according to the present disclosure preferably has a total content of the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (4), and the compound represented by formula (5) of 24 ppm or less. These compounds are all acetal compounds, and hydrolysis produces acetaldehyde. Acetaldehyde can be a substance that causes color, odor, or acidity.

[0053] In addition, in the 1,3-butylene glycol product according to the present disclosure, the acetaldehyde content is preferably less than 4 ppm (particularly, less than 2 ppm). Furthermore, the crotonaldehyde content is preferably less than 2 ppm (particularly, less than 1.2 ppm). As mentioned above, acetaldehyde and crotonaldehyde can be substances that cause coloration, odor, or acidity. Furthermore, they lower the potassium permanganate test value of the product. The acetaldehyde and crotonaldehyde contents in the 1,3-butylene glycol product can be quantified by the GC-MS analysis (gas mass spectrometry) described above.

[0054] Under the above GC-MS analysis conditions, when the relative retention time of the peak of 1,3-butylene glycol is taken as 1.0, the relative retention time of the peak of acetaldehyde is 0.3 to 0.5, and the relative retention time of the peak of crotonaldehyde is 0.3 to 0.5.

[0055] The acetaldehyde content in the 1,3-butylene glycol product is more preferably 1.8 ppm or less, even more preferably 1.7 ppm or less, 1.5 ppm or less, 1.4 ppm or less, 1.3 ppm or less, 1.2 ppm or less, 1.1 ppm or less, 1.0 ppm or less, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, or 0.5 ppm or less, and particularly preferably 0.3 ppm or less (e.g., 0.2 ppm or less).The crotonaldehyde content in the 1,3-butylene glycol product is more preferably 1.0 ppm or less, even more preferably 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.4 ppm or less, or 0.3 ppm or less, and particularly preferably 0.2 ppm or less (e.g., 0.1 ppm or less).

[0056] Furthermore, the 1,3-butylene glycol product preferably has an acid concentration (as acetic acid) of less than 11 ppm, and an acid concentration (as acetic acid) of less than 23 ppm after a 90% by weight aqueous solution is kept at 100°C for one week.

[0057] The 1,3-butylene glycol product according to the present disclosure desirably has an acid concentration (as acetic acid) of, for example, 10 ppm or less (preferably 9 ppm or less, more preferably 8 ppm or less, even more preferably 7 ppm or less, particularly preferably 6 ppm or less, and most preferably 5 ppm or less, 4 ppm or less, or 3 ppm or less), and the acid concentration (as acetic acid) after a 90 wt % aqueous solution is kept at 100°C for one week is, for example, 20 ppm or less (preferably 19 ppm or less, 18 ppm or less, 17 ppm or less, or 16 ppm or less, more preferably 15 ppm or less, even more preferably 14 ppm or less, 13 ppm or less, 12 ppm or less, or 11 ppm or less, and particularly preferably 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, or 2 ppm or less). The 90 wt % aqueous solution refers to an aqueous solution prepared by mixing a 1,3-butylene glycol product with water (for example, pure water) and adjusting the concentration of the 1,3-butylene glycol product to 90 wt %.

[0058] With regard to the acid concentration (as acetic acid) of a 90 wt % aqueous solution of the 1,3-butylene glycol product according to the present disclosure, the ratio of the acid concentration after being kept at 100°C for one week to the acid concentration before being kept [(acid concentration after being kept at 100°C for one week) / (acid concentration before being kept)×100(%)] is preferably 200% or less, more preferably 150% or less, and even more preferably 120% or less.

[0059] The 1,3-butylene glycol product according to the present disclosure desirably has an APHA (Hazen color scale) of, for example, 6 or less (preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and particularly preferably 2 or less), and an APHA after being maintained in an air atmosphere at 180°C for 3 hours of, for example, 78 or less (preferably 65 or less, more preferably 60 or less, even more preferably 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 20 or less, and particularly preferably 18 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, or 7 or less). Furthermore, the APHA after being kept in an air atmosphere at 100°C for 75 days is, for example, 42 or less (preferably 35 or less, 30 or less, 25 or less, 20 or less, 18 or less, 16 or less, 15 or less, 14 or less, or 13 or less; more preferably 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, or 6 or less; and even more preferably 5 or less, 4 or less, 3 or less, or 2 or less).

[0060] With regard to the APHA of the 1,3-butylene glycol product according to the present disclosure, the ratio of the APHA after 75 days at 100°C to the APHA before the holding [(APHA after 75 days at 100°C) / (APHA before the holding)] is not particularly limited, but is preferably 10 or less, more preferably 8 or less, even more preferably 7 or less, and particularly preferably 6 or less (for example, 5 or less, 4 or less, or 3 or less). The ratio may be 1 or more, and may be 2 or more.

[0061] Furthermore, the 1,3-butylene glycol product according to the present disclosure preferably has an initial boiling point of higher than 203° C. The initial boiling point is preferably 204° C. or higher, more preferably 205° C. or higher, even more preferably 206° C. or higher or 207° C. or higher, and particularly preferably 208° C. or higher.

[0062] Additionally, the 1,3-butylene glycol product according to the present disclosure preferably has a dry point of 209°C or less.

[0063] Furthermore, the 1,3-butylene glycol product according to the present disclosure preferably has a potassium permanganate test value (PMT) of 30 minutes or more, more preferably greater than 30 minutes (e.g., 32 minutes or more), even more preferably 35 minutes or more (e.g., 40 minutes or more), and particularly preferably 50 minutes or more (especially 60 minutes or more).

[0064] Furthermore, in the 1,3-butylene glycol product according to the present disclosure, the area ratio of the 1,3-butylene glycol peak (GC area ratio) is preferably higher than 98.7% in gas chromatography analysis (GC analysis) under the following conditions. Furthermore, the total area ratio of peaks with shorter retention times than the 1,3-butylene glycol peak is preferably lower than 0.3%. Furthermore, the total area ratio of peaks with longer retention times than the 1,3-butylene glycol peak is preferably lower than 1.2%. (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[0065] In the present disclosure, the "area ratio" of a peak refers to the ratio of the area of ​​a specific peak to the sum of the areas of all peaks appearing in a chart. Furthermore, "all peaks" refers to, for example, all peaks that appear when the analysis is continued until the relative retention time reaches 7.8, assuming that the relative retention time of the 1,3-butylene glycol peak is 1.0, and then stopped. When the area ratio of the peaks is within the above range, odor generation, an increase in acid concentration over time in a water-containing state, and coloration over time tend to be reduced.

[0066] The area ratio of the peak of the 1,3-butylene glycol is preferably 98.8% or more, more preferably 98.9% or more, even more preferably 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, 99.6% or more, or 99.7% or more, and particularly preferably 99.8% or more.

[0067] The total area ratio of peaks having retention times shorter than that of the 1,3-butylene glycol peak is preferably 0.28% or less, more preferably 0.25% or less, even more preferably 0.23% or less, 0.2% or less, 0.17% or less, 0.15% or less, 0.12% or less, 0.1% or less, 0.07% or less, 0.04% or less, 0.03% or less, 0.02% or less, 0.01% or less, or 0.007% or less, and particularly preferably 0.005% or less (e.g., 0.002% or less).

[0068] The total area ratio of peaks having a longer retention time than the peak of 1,3-butylene glycol is preferably 1% or less, more preferably 0.9% or less, even more preferably 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less, and particularly preferably 0.1% or less.

[0069] In the 1,3-butylene glycol product according to the present disclosure, the water content is preferably less than 0.4% by weight. The water content is preferably 0.3% by weight or less, more preferably 0.2% by weight or less, even more preferably 0.1% by weight or less, 0.07% by weight or less, 0.05% by weight or less, 0.03% by weight or less, 0.02% by weight or less, or 0.01% by weight or less, and particularly preferably 0.005% by weight or less. The water content can be quantified using a Karl Fischer moisture analyzer.

[0070] In addition to reducing the contents of the nine specific compounds, by having the acetaldehyde content and the crotonaldehyde content within the above ranges, by having the initial boiling point and the dry point within the above ranges, and by having the potassium permanganate test value, the area ratio of the 1,3-butylene glycol peak, the total area ratio of peaks having shorter retention times than the 1,3-butylene glycol peak, and the total area ratio of peaks having longer retention times than the 1,3-butylene glycol peak within the above ranges, a 1,3-butylene glycol product that is highly pure and high quality and that deteriorates little over time in quality is provided.

[0071] [Moisturizers and cosmetics] The moisturizing agent of the present disclosure contains the 1,3-butylene glycol product described above. Therefore, it has excellent moisturizing performance. The moisturizing agent of the present disclosure may contain components other than the 1,3-butylene glycol product described above, for example, moisturizing agent components other than the 1,3-butylene glycol product described above. The moisturizing agent of the present disclosure may contain, for example, 10% by weight or more of the 1,3-butylene glycol product, preferably 30% by weight or more, more preferably 50% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more. The moisturizing agent may be composed solely of the 1,3-butylene glycol product described above.

[0072] The cosmetic preparation of the present disclosure contains the moisturizing agent described above. The amount of the 1,3-butylene glycol product in the cosmetic preparation of the present disclosure may be any amount that can exhibit moisturizing properties, depending on the type and form of the cosmetic. The amount of the 1,3-butylene glycol product in the cosmetic preparation of the present disclosure is, for example, 0.01 to 40 wt %, preferably 0.1 to 30 wt %, more preferably 0.2 to 20 wt %, even more preferably 0.5 to 15 wt %, and particularly preferably 1 to 10 wt %.

[0073] In addition to the 1,3-butylene glycol product, the cosmetic composition of the present disclosure may contain, for example, other moisturizers; oils such as vegetable oils, hydrocarbon oils, higher fatty acids, higher alcohols, and silicones; surfactants such as anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants; preservatives, sequestering agents, thickeners, powders, UV absorbers, UV blockers, fragrances, pH adjusters; medicinal ingredients and physiologically active ingredients such as vitamins, skin activators, blood circulation promoters, whitening agents, antibacterial agents, and anti-inflammatory agents.

[0074] The cosmetic of the present disclosure may be a skin cosmetic such as a lotion, emulsion, cream, gel, pack, or mask, or a hair cosmetic such as a shampoo, rinse, or hair growth agent. It may also be a sunscreen cosmetic, a makeup cosmetic, or the like. It may also be a pharmaceutical or quasi-drug containing a medical ingredient.

[0075] The cosmetic composition of the present disclosure can be produced by utilizing a method known per se.

[0076] [Method of producing 1,3-butylene glycol] The 1,3-butylene glycol product according to the present disclosure can be produced by the production method according to the present disclosure. Production method 1 according to the present disclosure is a method for producing 1,3-butylene glycol from a crude reaction liquid containing 1,3-butylene glycol (1,3BG) (hereinafter, sometimes referred to as "crude 1,3-butylene glycol"), and includes a dehydration step for removing water by distillation, a high-boiling point removal step for removing high-boiling components by distillation, and a product distillation step for obtaining purified 1,3-butylene glycol. In the product column used in the product distillation step, a 1,3-butylene glycol feed solution having an acetaldehyde content of 500 ppm or less, a crotonaldehyde content of 200 ppm or less, a water content of 0.7 wt% or less, and a 1,3-butylene glycol concentration of 97.6 area% or more as determined by gas chromatography analysis under the conditions described below is subjected to distillation under conditions of a reflux ratio of 0.3 or more, and a liquid concentrated with low boiling point components is distilled from above the feed stage, and 1,3-butylene glycol is extracted from below the feed stage. The 1,3-butylene glycol obtained in this manner is colorless and odorless (or almost colorless and odorless), does not easily become discolored over time, and is also not susceptible to an increase in acid concentration over time even when containing water, and can therefore be used as a 1,3-butylene glycol product. (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[0077] Production method 2 of the present disclosure is a method for producing 1,3-butylene glycol from a reaction crude liquid containing 1,3-butylene glycol, and includes a dehydration step for removing water by distillation and a high-boiling component removal step for removing high-boiling components by distillation. In the high-boiling component removal tower used in the high-boiling component removal step, a feed liquid containing 1,3-butylene glycol having an acetaldehyde content of 500 ppm or less, a crotonaldehyde content of 200 ppm or less, a water content of 3 wt% or less, and a 1,3-butylene glycol concentration of 96.7 area % or more as determined by gas chromatography analysis under the conditions described below is subjected to distillation at a reflux ratio of 0.03 or more, and 1,3-butylene glycol with improved purity is distilled from above the feed stage, and a liquid in which the high-boiling components are concentrated is withdrawn from below the feed stage. The 1,3-butylene glycol obtained in this manner is colorless and odorless (or nearly colorless and odorless), does not easily become colored over time, and is also not susceptible to an increase in acid concentration over time even when containing water, making it suitable for use as a 1,3-butylene glycol product.

[0078] The "Manufacturing Method 1 of the Present Disclosure" and the "Manufacturing Method 2 of the Present Disclosure" may be collectively referred to as the "Manufacturing Method of the Present Disclosure."

[0079] [Crude 1,3-butylene glycol] Examples of crude 1,3-butylene glycol include (1) a reaction crude liquid obtained by the reduction (hydrogenation) of acetaldols, (2) a reaction crude liquid obtained by the hydrolysis of 1,3-butylene oxide, (3) a reaction crude liquid obtained by the selective hydrogenolysis of erythritol, (4) a reaction crude liquid obtained by the selective addition of water to butadiene, (5) a reaction crude liquid obtained by the hydrogenation of n-butanal-3-one, (6) a reaction crude liquid obtained by the hydrogenation of 1-butanol-3-one, (7) a reaction crude liquid obtained by the hydrogenation of 3-hydroxy-1-butanoic acid, (8) a reaction crude liquid obtained by the hydrogenation of β-butyrolactone, and (9) a reaction crude liquid obtained by the hydrogenation of diketene. In the present disclosure, crude 1,3-butylene glycol may be one or a mixture of two or more of the above (1) to (9). The crude 1,3-butylene glycol is preferably a crude reaction liquid obtained by the reduction (particularly, liquid phase reduction) of acetaldols in the above (1).

[0080] Hereinafter, a case where a crude reaction liquid obtained by reduction (hydrogenation) of acetaldols is used as crude 1,3-butylene glycol will be mainly described. The step of reducing (hydrogenating) acetaldols may also be referred to as the "hydrogenation step."

[0081] The acetaldol used as a raw material in the hydrogenation step is not particularly limited as long as it is a compound that can be converted to 1,3-butylene glycol by hydrogen reduction. Examples of the raw material acetaldol include acetaldol, its cyclized dimer, para-aldol, aldoxane, a cyclic trimer of acetaldehyde, and mixtures thereof.

[0082] The method for producing acetaldols (e.g., acetaldol and para-aldol) is not particularly limited, but may be, for example, those obtained by an aldol condensation reaction of acetaldehyde in the presence of a basic catalyst, or those obtained by thermal decomposition of aldoxane, etc. The process for producing acetaldols may be referred to as an "acetaldol production process" or an "acetaldehyde polymerization process."

[0083] The reaction crude liquid containing acetaldols obtained by the above reaction may be neutralized with an acid and used to produce 1,3-butylene glycol. In addition to acetaldols, such a reaction crude liquid may contain acetaldehyde (AD), crotonaldehyde (CR), other aldehyde components, low-boiling substances, high-boiling substances such as aldehyde dimers and trimers, water, salts, etc. In this specification, compounds having a boiling point lower than that of 1,3-butylene glycol may be referred to as "low-boiling substances" or "low-boiling products," and compounds having a boiling point higher than that of 1,3-butylene glycol may be referred to as "high-boiling substances" or "high-boiling products."

[0084] The reaction crude liquid containing the acetaldols may be subjected to pretreatment such as dealcoholization distillation, dehydration distillation, desalting, alkali treatment, dealkalization treatment, and impurity removal, as necessary, to remove by-products such as unreacted acetaldehyde and crotonaldehyde, and may be used after that. Pretreatment methods include distillation, adsorption, ion exchange, heating to convert to high boiling point substances, and decomposition. Various distillation methods can be used for distillation, such as reduced pressure, normal pressure, increased pressure, azeotropy, extraction, and reaction. In particular, it is preferred to subject the reaction crude liquid containing acetaldols to simple evaporation, distillation, or hydrogenation to remove aldehydes such as acetaldehyde and crotonaldehyde, and then subject the resulting product to a hydrogenation step.

[0085] The content of acetaldols in the hydrogenation raw material is not particularly limited, but is, for example, 30% by weight or more (e.g., 30 to 99% by weight), more preferably 40% by weight or more (e.g., 40 to 98% by weight), 50% by weight or more (e.g., 50 to 97% by weight), or 60% by weight or more (e.g., 60 to 95% by weight), even more preferably 65 to 90% by weight, particularly preferably 70 to 90% by weight, and most preferably 75 to 90% by weight. When the content of acetaldols is within the above range, impurities contained in the reaction crude liquid containing 1,3-butylene glycol (crude 1,3-butylene glycol) tend to be reduced.

[0086] The hydrogenation raw material may or may not contain water, but preferably does so from the viewpoint of the purity of the 1,3-butylene glycol product. The water content of the hydrogenation raw material is not particularly limited, but is preferably, for example, 2% by weight or more, more preferably 5% by weight or more, even more preferably 10% by weight or more, and particularly preferably 15% by weight or more. The upper limit may be, for example, 90% by weight, 80% by weight, 70% by weight, 60% by weight, 50% by weight, 40% by weight, 30% by weight, or 20% by weight. When the water content is within the above range, the amount of acetal compounds between 1,3-butylene glycol and acetaldol contained in the obtained crude 1,3-butylene glycol is reduced, and therefore the purity of the finally obtained 1,3-butylene glycol product tends to be higher. This is because the presence of a certain amount of water in the hydrogenation raw material causes the acetal compounds to be hydrolyzed to 1,3-butylene glycol, and the co-produced acetaldol is reduced to 1,3-butylene glycol.

[0087] Examples of hydrogenation catalysts include Raney nickel. The hydrogenation catalyst can be used in a suspended state or packed in a reaction vessel. The amount of hydrogenation catalyst used is not particularly limited, but is preferably 1 to 30 parts by weight, more preferably 4 to 25 parts by weight, even more preferably 8 to 20 parts by weight, and particularly preferably 12 to 18 parts by weight, per 100 parts by weight of the hydrogenation raw material. The amount of hydrogen used in the reduction reaction is not particularly limited, but is preferably 0.5 to 40 parts by weight, more preferably 1 to 30 parts by weight, even more preferably 4 to 20 parts by weight, and particularly preferably 8 to 12 parts by weight, per 100 parts by weight of the hydrogenation raw material. The pressure in the reaction system (total pressure; gauge pressure) in the reduction reaction is not particularly limited, but is, for example, 9 to 70 MPa, preferably 10 to 40 MPa. The hydrogen pressure (hydrogen partial pressure) in the reaction system is not particularly limited, but is, for example, 7 to 60 MPa, preferably 10 to 30 MPa. From the viewpoint of reducing reducing substances such as acetaldehyde and crotonaldehyde, it is advisable to increase the hydrogen pressure in the reaction system, preferably 10 MPa or more, and even 100 MPa. The reaction temperature in the reduction reaction is not particularly limited, but is, for example, 40 to 150°C, preferably 50 to 140°C, and more preferably 60 to 130°C. The reaction time (residence time) in the reduction reaction is not particularly limited, but is, for example, 10 to 500 minutes, preferably 20 to 400 minutes, more preferably 30 to 300 minutes, even more preferably 50 to 280 minutes, and particularly preferably 80 to 250 minutes. This reaction can be carried out in any of a batch system, a semi-batch system, and a continuous system.

[0088] The crude 1,3-butylene glycol thus obtained contains low-boiling substances (low-boiling compounds) having unsaturated bonds, such as acetaldehyde (AD), butylaldehyde, crotonaldehyde (CR), acetone, and methyl vinyl ketone, as well as condensates thereof, condensates of 1,3-butylene glycol with the above-mentioned low-boiling substances (for example, acetals formed from 1,3-butylene glycol and acetaldol), alcohols such as ethanol, isopropyl alcohol, and butanol, water (solvent), salts produced by neutralization treatment, and catalysts (when used in suspension). By removing these impurities in a purification step, a 1,3-butylene glycol product (purified 1,3-butylene glycol) can be obtained.

[0089] [Purification of crude 1,3-butylene glycol] Production method 1 of the present disclosure includes at least a dehydration step of removing water by distillation, a high boiling point removal step of removing high boiling point components by distillation (high boiling point removal distillation step), and a product distillation step for obtaining purified 1,3-butylene glycol. Production method 2 of the present disclosure includes at least a dehydration step of removing water by distillation and a high boiling point removal step of removing high boiling point components by distillation (high boiling point removal distillation step).

[0090] In the production method of the present disclosure, the order of the dehydration step and the high-boiling point removal step does not matter. In Production Method 1 of the present disclosure, both the dehydration step and the high-boiling point removal step are performed before the product distillation step. In addition to these steps, the production method of the present disclosure may also include a desalting step, an alkali reaction step (alkali treatment step), and a dealkalization step. Furthermore, a catalyst separation step, an alkali neutralization step, and a dealcoholization step (low-boiling point removal step) may also be performed before the dehydration step. The above steps may be performed in the order described above, but the order of the steps may be changed as appropriate, except that the dealcoholization step is performed after the alkali reaction step. For example, the dealcoholization step (low-boiling point removal step), desalting step, alkali reaction step, and dealkalization step may be performed at any appropriate location, but are typically performed after the hydrogenation step. Among the above steps, the catalyst separation step, alkali neutralization step, dealcoholization step (low-boiling point removal step), desalting step, alkali reaction step, and dealkalization step may be performed as needed, but are not necessarily required.

[0091] FIG. 1 is a flow sheet of an apparatus showing an example of an embodiment of the method for producing 1,3-butylene glycol of the present disclosure. A is a dehydrating tower and is related to the dehydration step. B is a demineralizing tower and is related to the demineralizing step. C is a high boiler removal distillation tower (high boiler removal tower) and is related to the high boiler removal distillation step (high boiler removal step). D is an alkali reactor and is related to the alkali reaction step. E is a dealkalizing tower and is related to the dealkalizing step. F is a product distillation tower (product tower) and is related to the product distillation step. A-1, B-1, C-1, E-1, and F-1 are condensers. A-2, C-2, and F-2 are reboilers. Hereinafter, an example of an embodiment of the method for producing 1,3-butylene glycol of the present disclosure will be described using this flow sheet.

[0092] Crude 1,3-butylene glycol (corresponding to "X-1") obtained by hydrogen reduction of the hydrogenated raw material is supplied to the dehydration tower A. The crude 1,3-butylene glycol (corresponding to "X-1") may be supplied to the dehydration tower A after undergoing a dealcoholization step (distillation step using a dealcoholization tower) for removing alcohols such as ethanol and low boiling points.

[0093] In the production method of the present disclosure, in the dehydration column A used in the dehydration step, for example, a feed liquid containing 1,3-butylene glycol and water is subjected to distillation, and a liquid concentrated with low-boiling components including water is distilled from above the feed stage (preferably the top of the column) (corresponding to "X-2" in FIG. 1). Also, a crude 1,3-butylene glycol stream containing 1,3-butylene glycol is obtained from below the feed stage (preferably the bottom of the column).

[0094] Dehydration column A and other distillation columns for separating 1,3-butylene glycol can be, for example, perforated plate columns or bubble cap columns. However, packed columns with low pressure loss, such as Sulzer Packing or Melapak (both trade names of Sumitomo Heavy Industries, Ltd.), are preferred. This is because 1,3-butylene glycol and trace impurities contained therein undergo thermal decomposition at high temperatures (e.g., 150°C or higher) to produce low-boiling substances that cause coloration, and therefore the distillation temperature must be low. Furthermore, a long thermal history (residence time) of 1,3-butylene glycol can have a similar effect. Therefore, the reboiler used should be one with a short residence time for the process fluid, such as a gravity-flow thin-film evaporator or a forced-agitation thin-film evaporator.

[0095] The number of theoretical plates in the dehydrating column A is, for example, 1 to 100, preferably 2 to 80, 3 to 80, 4 to 60, 5 to 40, 6 to 30, or 7 to 20, and more preferably 8 to 15. The feed position of the charge liquid is, for example, 10 to 90%, preferably 20 to 80%, more preferably 30 to 70%, and even more preferably 40 to 60% of the height of the column downward from the top of the column. In the distillation in the dehydrating column A, the pressure (absolute pressure) at the top of the column is, for example, 101 kPa or less, preferably 0.1 to 90 kPa, more preferably 0.5 to 70 kPa, even more preferably 1 to 50 kPa, 2 to 30 kPa, or 3 to 20 kPa, and particularly preferably 4 to 10 kPa. The distillation in the dehydration column A may be carried out under pressure, and in that case, the pressure (gauge pressure) at the top of the column may be, for example, 0.2 MPaG or less, or 0.1 MPaG or less.

[0096] The concentration of 1,3-butylene glycol in the liquid fed to dehydrating tower A is, for example, 9% by weight or more, preferably 10% by weight or more, more preferably 15% by weight or more, even more preferably 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or more, and particularly preferably 70% or more. The upper limit of the concentration of 1,3-butylene glycol in the liquid fed to dehydrating tower A is, for example, 90% by weight, 85% by weight, or 80% by weight. However, in consideration of the hydrogenation reaction in the step before the dehydration step, etc., a higher water concentration in the liquid fed to dehydrating tower A may be preferable. Taking all of this into consideration, the concentration of 1,3-butylene glycol in the feed liquid to dehydration column A may be, for example, 1% by weight or more, 5% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. In addition, the concentration of 1,3-butylene glycol in the feed liquid to dehydration column A may be, for example, 99% by weight or less, 95% by weight or more, 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, or 45% by weight or less. The concentration of 1,3-butylene glycol in the liquid charged to the dehydrating tower A can be adjusted to the above range by, for example, adjusting the reaction conditions in the hydrogenation step (e.g., the concentration of acetaldols used as a raw material) and the distillation conditions of a dealcoholization tower (low boiling point removal tower) that is installed as needed before the dehydrating tower.

[0097] The concentration (wt%) of 1,3-butylene glycol was determined by calculating the ratio of the area of ​​the 1,3-butylene glycol peak to the total peak area (GC area%) in gas chromatography analysis under the following conditions, and then calculating it using the following formula: The concentration (wt%) of water in the liquid charged to dehydration tower A was measured by the method described below (Karl Fischer method). Concentration of 1,3-butylene glycol in the feed liquid to dehydration tower A (wt%) = (1 - water concentration in the feed liquid to dehydration tower A (wt%) / 100) x GC area % of the above 1,3-butylene glycol (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[0098] In the production method of the present disclosure, the content of acetaldehyde in the feed liquid to dehydration tower A is, for example, 1000 ppm or less, preferably 900 ppm or less, more preferably 800 ppm or less, 700 ppm or less, 600 ppm or less, or 500 ppm or less, and even more preferably 400 ppm or less, 300 ppm or less, 200 ppm or less, 155 ppm or less, or 140 ppm or less, and may be 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or 1 ppm or less.

[0099] The content of crotonaldehyde in the feed liquid to dehydration tower A is, for example, 400 ppm or less, preferably 300 ppm or less, more preferably 200 ppm or less, even more preferably 150 ppm or less, 130 ppm or less, 117 ppm or less, or 100 ppm or less, and may be 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or 1 ppm or less.

[0100] The acetaldehyde and crotonaldehyde contents in the feed liquid to dehydrating tower A can be reduced, for example, by providing a dealcoholization tower (low boiling point removal tower) upstream of dehydrating tower A and adjusting the distillation conditions of the dealcoholization tower (low boiling point removal tower). For example, the acetaldehyde and crotonaldehyde contents in the feed liquid to dehydrating tower A can be reduced by increasing the reflux ratio, number of stages, and distillate yield of the dealcoholization tower (low boiling point removal tower). Furthermore, the acetaldehyde and crotonaldehyde contents can also be adjusted by the conditions of the hydrogenation reaction in the hydrogenation step. When hydrogenation is completed, the acetaldehyde and crotonaldehyde concentrations can be reduced to below the detection limit, but disadvantages such as an increase in reaction pressure and a larger reaction tank arise.

[0101] The acetaldehyde content and crotonaldehyde content in the liquid fed to the dehydration tower A can be determined quantitatively by GC-MS analysis (gas mass spectrometry).

[0102] In the production method of the present disclosure, the water content in the liquid fed to dehydration tower A is, for example, 90% by weight or less, 85% by weight or less, 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, or 40% by weight or less, preferably 35% by weight or less, more preferably 30% by weight or less, and even more preferably 25% by weight or less. The lower limit of the water content in the liquid fed to dehydration tower A is, for example, 15% by weight or 10% by weight. In addition, when considering the hydrogenation reaction in the hydrogenation step, a high water concentration and low viscosity are advantageous for the hydrogenation reaction because they increase the solubility and dispersibility of hydrogen in the liquid. The water content in the liquid fed to dehydration tower A can be reduced, for example, by providing a dealcoholization tower (low boiling point removal tower) upstream of dehydration tower A and adjusting the distillation conditions of the dealcoholization tower (low boiling point removal tower). For example, the water content in the liquid charged to the dehydrating tower A can be reduced by increasing the reflux ratio, number of stages, and distillate rate of the dealcoholization tower (low boiling point removal tower). The water content in the liquid charged to the dehydrating tower A can be quantified using a Karl Fischer water content meter.

[0103] In the production method of the present disclosure, the content of low-boiling components (excluding water) in the feed liquid to dehydrating tower A is, for example, 20% or less, preferably 10% or less, more preferably 8% or less, even more preferably 5% or less, particularly preferably 3% or less or 2% or less, and may be 1% or less, 0.5% or less, or 0.1% or less. The content of low-boiling components excluding water (also referred to as "low boilers" or "low boilers") in the feed liquid to dehydrating tower A is the ratio (area %) of the total area of ​​peaks having a shorter retention time than the peak of 1,3-butylene glycol to the total peak area in gas chromatography analysis under the above conditions. The content of low-boiling components (excluding water) in the feed liquid to dehydrating tower A can be reduced, for example, by providing a dealcoholization tower (low boiling tower) upstream of dehydrating tower A and adjusting the distillation conditions of the dealcoholization tower (low boiling tower). For example, by increasing the reflux ratio, number of stages, or distillate rate of the dealcoholization tower (low boiling point removal tower), it is possible to reduce the concentration of low boiling point components (excluding water) in the liquid fed to the dehydration tower A. In addition, the concentration of low boiling point components (excluding water) in the liquid fed to the dehydration tower A can also be reduced by, for example, the reaction conditions (e.g., reaction temperature) in the hydrogenation step.

[0104] The content of high-boiling components in the liquid fed to dehydrating column A is, for example, 20% or less, preferably 10% or less, more preferably 7% or less, 4% or less, 3% or less, or 2% or less, even more preferably 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, or 0.05% or less, and particularly preferably 0.01% or less. The content of high-boiling components in the liquid fed to dehydrating column A can be adjusted, for example, by the reaction conditions in the hydrogenation step (e.g., reaction temperature, etc.). The content of high-boiling components in the liquid fed to dehydrating column A is the ratio (area %) of the total area of ​​peaks having a longer retention time than the 1,3BG peak to the total peak area in gas chromatography analysis under the above conditions.

[0105] In the production method of the present disclosure, the reflux ratio in the dehydrating tower A [amount refluxed to the dehydrating tower / amount distilled out of the dehydrating tower (amount discharged outside the distillation tower)] is, from the viewpoint of reducing the content of low boilers (including water) in a crude 1,3-butylene glycol stream containing 1,3-butylene glycol taken out from below the feed tray of the dehydrating tower A (preferably from the bottom of the tower), for example, more than 0.3, preferably 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 15 or more, 20 or more, or 25 or more, and more preferably 30 or more (e.g., 40 or more). In particular, in Production Method 2 of the present disclosure, the reflux ratio in dehydrating tower A is preferably 10 or more, more preferably 20 or more, even more preferably 30 or more, and particularly preferably 50 or more. From the viewpoint of energy costs, the upper limit of the reflux ratio is, for example, 100, preferably 50. When the number of theoretical plates in dehydrating tower A is large, sufficient separation is possible even if the reflux ratio is 10 or 20 or less.

[0106] In the production method of the present disclosure, the distillation rate in dehydrating tower A can be appropriately set depending on the concentration of water in the feed liquid to dehydrating tower A. The distillation rate is desirably a rate sufficient to distill off all of the water in the feed liquid. For example, when the water concentration in the feed liquid to dehydrating tower A is X% by weight, the distillation rate in dehydrating tower A is preferably X% by weight or more. Therefore, the distillation rate in dehydrating tower A is, for example, 95% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, or 5% by weight or less. The distillate yield refers to the ratio (wt %) of the amount of liquid withdrawn from the dehydrating tower A above the feed tray (for example, the top of the tower) to the amount charged to the dehydrating tower A.

[0107] In the production method of the present disclosure, the 1,3BG recovery rate in the dehydration tower A is, for example, 99.3% or more. In this specification, the 1,3BG recovery rate in the dehydration tower A is a value (%) calculated by the following formula: {1 - [1,3BG concentration in distillate (wt%) x (distillate volume (parts) - recycled volume (parts))] / (1,3BG concentration in feed solution (wt%) x feed volume (parts))} x 100 Furthermore, low-boiling and high-boiling substances may be hydrolyzed with water to produce 1,3BG, while high-boiling substances may be produced by polymerization of 1,3BG. Furthermore, trace impurities may be produced or lost, so the material balance in the dehydration tower may not always be achieved. This also applies to other distillation towers, such as dealcoholization towers (low-boiling towers), high-boiling towers, and product towers.

[0108] Next, a crude 1,3-butylene glycol stream containing 1,3-butylene glycol withdrawn from the dehydrating tower A below the feed tray (preferably from the bottom) is supplied to a demineralizing tower B. In the demineralizing tower B, a crude 1,3-butylene glycol stream after desalting is obtained from the top of the tower by distillation, and salts, high boiling point substances, etc. are discharged as bottoms from the bottom of the tower. The bottoms rate (%) of the demineralizing tower B [(demineralizing tower bottoms amount (parts) / demineralizing tower charge amount (parts)) × 100] is, for example, 0.1 to 40 wt%, preferably 1 to 35 wt%, more preferably 2 to 30 wt%, even more preferably 3 to 25 wt%, particularly preferably 5 to 20 wt%, and may be 7 to 15 wt%. At least a portion of the bottoms from the demineralizing tower may be recycled to a process prior to the desalting step.

[0109] The crude 1,3-butylene glycol stream after the desalting is supplied to a high boiling removal column C. In the high boiling removal column C, high boiling components (high boilers) are discharged from below the feed tray (preferably from the bottom of the column). On the other hand, a crude 1,3-butylene glycol stream after the high boilers have been removed (1,3-butylene glycol with improved purity) is obtained from above the feed tray.

[0110] Although perforated plate columns, bubble cap columns, and the like can be used as the high-boiling column C, a packed column with low pressure loss, such as Sulzer Packing or Melapak (both trade names of Sumitomo Heavy Industries, Ltd.), is more preferred. This is because 1,3-butylene glycol and trace amounts of impurities contained therein undergo thermal decomposition at high temperatures (e.g., 150°C or higher), producing low-boiling substances that cause coloration, and therefore the distillation temperature must be low. Furthermore, a long thermal history (residence time) of 1,3-butylene glycol can have a similar effect. Therefore, the reboiler used is preferably one with a short residence time for the process fluid, such as a gravity-flow thin-film evaporator or a forced-agitation thin-film evaporator.

[0111] The number of theoretical plates in the high boiling removal column C is, for example, 1 to 100, preferably 2 to 90, more preferably 3 to 80, even more preferably 4 to 70, 5 to 60, 8 to 50, or 10 to 40, and particularly preferably 15 to 30. The feed position of the charge liquid is, from the top of the high boiling removal column downward, for example, 10 to 90%, preferably 20 to 80%, more preferably 30 to 70, and even more preferably 40 to 60% of the height of the column. In the distillation in the high boiling removal column C, the pressure (absolute pressure) at the top of the column is, for example, 0.01 to 50 kPa, preferably 0.1 to 30 kPa, more preferably 0.3 to 20 kPa, and even more preferably 0.5 to 10 kPa.

[0112] In Production Method 1 of the present disclosure, the concentration of 1,3BG in the feed liquid to high boiling desorption tower C is, for example, 95% or more, preferably 96% or more (e.g., 96.7% or more), more preferably 97% or more, even more preferably 98% or more, and particularly preferably 99% or more. In Production Method 2 of the present disclosure, the concentration of 1,3BG in the feed liquid to high boiling desorption tower C is 96.7% or more, preferably 97% or more, more preferably 98% or more, and even more preferably 99% or more. The concentration of 1,3BG in the feed liquid to high boiling desorption tower C can be improved by adjusting the distillation conditions of dehydrating tower A and demineralizing tower B. For example, the concentration of 1,3BG in the feed liquid to high boiling desorption tower C can be increased by increasing the reflux ratio of dehydrating tower A or increasing the bottoms rate of demineralizing tower B. The above concentration of 1,3BG is the ratio (area %) of the area of ​​the 1,3BG peak to the total peak area in gas chromatography analysis (GC analysis) under the following conditions. (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[0113] The content of high boiling point components in the feed liquid to high boiling desorption tower C is, for example, 4% or less, preferably 3% or less, more preferably 2% or less, even more preferably 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, or 0.05% or less, and particularly preferably 0.01% or less. In particular, in production method 2 of the present disclosure, the content of high boiling point components in the feed liquid to high boiling desorption tower C is preferably 3% or less, more preferably 2% or less, even more preferably 1.5% or less, 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, or 0.05% or less, and particularly preferably 0.01% or less. The content of high boiling point components in the feed liquid to high boiling desorption tower C can be reduced by adjusting the distillation conditions of the demineralization tower B. For example, the content of high boiling point components in the liquid fed to high boiling desorption column C can be reduced by increasing the bottoms rate of demineralization column B. The content of high boiling point components in the liquid fed to high boiling desorption column C is the ratio (area %) of the total area of ​​peaks with longer retention times than the peak of 1,3BG to the total peak area in gas chromatography analysis under the above conditions.

[0114] In the production method of the present disclosure, the content of acetaldehyde in the feed liquid to high boiling removal column C is, for example, 500 ppm or less, preferably 205 ppm or less (e.g., 200 ppm or less), more preferably 100 ppm or less, even more preferably 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, or 10 ppm or less, and particularly preferably 5 ppm or less, and may be less than 2 ppm or less than 1 ppm. The crotonaldehyde content in the feed liquid to high boiling desorption column C is, for example, 200 ppm or less, preferably 110 ppm or less, more preferably 100 ppm or less, even more preferably 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, or 3 ppm or less, and particularly preferably 2 ppm or less, and may even be less than 1 ppm. The acetaldehyde content and crotonaldehyde content in the feed liquid to high boiling desorption column C can be reduced, for example, by providing a dealcoholization column (low boiling desorption column) or a dehydration column upstream of high boiling desorption column C and adjusting the distillation conditions of the dealcoholization column (low boiling desorption column) or the dehydration column. For example, by increasing the reflux ratio, number of stages, and distillate yield of the dealcoholization tower (low boiling removal tower) and the dehydration tower, it is possible to reduce the acetaldehyde content and the crotonaldehyde content in the liquid fed to the high boiling removal tower C. The acetaldehyde content and the crotonaldehyde content in the liquid fed to the high boiling removal tower C can be quantified by GC-MS analysis (gas mass spectrometry).

[0115] In the production method of the present disclosure, the water content in the feed liquid to high boiling removal column C is, for example, 3% by weight or less, preferably 2% by weight or less, more preferably 1.2% by weight or less, even more preferably 1.1% by weight or less, 1.0% by weight or less, 0.95% by weight or less, 0.9% by weight or less, 0.8% by weight or less, 0.7% by weight or less, 0.6% by weight or less, 0.5% by weight or less, 0.4% by weight or less, 0.3% by weight or less, or 0.2% by weight or less, and particularly preferably 0.1% by weight or less. The water content in the feed liquid to high boiling removal column C can be reduced by adjusting the distillation conditions of the dehydrating column A. For example, the water concentration in the feed liquid to high boiling removal column C can be reduced by increasing the reflux ratio, number of stages, or distillate rate of the dehydrating column A. The water content in the feed liquid to high boiling removal column CF can be quantified using a Karl Fischer water content meter. In addition, in the production method 2 of the present disclosure, the water content in the liquid fed to the high boiling removal tower C is 3% by weight or less, preferably 2% by weight or less, 1.2% by weight or less, 0.4% by weight or less, 0.3% by weight or less, or 0.2% by weight or less, and particularly preferably 0.1% by weight or less, 0.05% by weight or less, or 0.03% by weight or less.

[0116] In the production method of the present disclosure, the content of low-boiling components (excluding water) in the liquid fed to high boiling removal column C is, for example, 1.8% or less, preferably 1.6% or less, more preferably 1.4% or less, even more preferably 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less, and particularly preferably 0.1% or less. The content of low-boiling components excluding water (also referred to as "low boilers" or "low boilers") in the liquid fed to high boiling removal column C is the ratio (area %) of the total area of ​​peaks having a shorter retention time than the peak of 1,3-butylene glycol to the total peak area in gas chromatography analysis under the above conditions. The content of low boiling point components (excluding water) in the liquid fed to the high boiling decoupling tower C can be reduced, for example, by providing a dealcoholization tower (low boiling decoupling tower) upstream of the high boiling decoupling tower C and adjusting the distillation conditions of the dealcoholization tower (low boiling decoupling tower). For example, the concentration of low boiling point components (excluding water) in the liquid fed to the high boiling decoupling tower C can be reduced by increasing the reflux ratio, number of stages, or distillate yield of the dealcoholization tower (low boiling decoupling tower).

[0117] In the production method of the present disclosure, the reflux ratio in high boiling removal column C [amount refluxed to high boiling removal column / amount distilled from high boiling removal column (amount discharged outside the distillation column)] is, from the viewpoint of lowering the dry point of the 1,3-butylene glycol product, 0.03 or more, preferably 0.05 or more, more preferably 0.1 or more, even more preferably 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 10 or more, and particularly preferably 20 or more. In particular, in Production Method 2 of the present disclosure, the reflux ratio in high boiling removal tower C is preferably 0.1 or more, more preferably 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 10 or more, and particularly preferably 20 or more. From the viewpoint of energy costs, the upper limit of the reflux ratio is, for example, 100, preferably 50. When the number of theoretical plates in high boiling removal tower C is large, sufficient separation is possible even if the reflux ratio in high boiling removal tower C is about 1 or less.

[0118] In the production method of the present disclosure, by setting the reflux ratio in high boiling point removal tower C within the above range, high-purity 1,3BG with an extremely low content of high-boiling point components and a low dry point can be produced at a high recovery rate.

[0119] In the production method of the present disclosure, the bottoms yield of the high boiling removal tower C is, for example, less than 30% by weight. However, this is not the case when the bottoms of the high boiling removal tower are distilled in an additional distillation tower to remove high boiling components and then commercialize the resulting 1,3BG. 1,3BG can be obtained in high yield by limiting the final amount of high boiling components withdrawn from the system to less than 30% by weight of the amount charged to the high boiling removal tower C. The bottoms yield refers to the ratio (by weight) of the amount of liquid withdrawn from below the feed tray of the high boiling removal tower C (for example, from the bottom of the tower) to the amount charged to the high boiling removal tower C (including the recycled amount if this liquid is recycled to the previous process described below). When this liquid is recycled to the previous process described below, the lower the outflow rate, the higher the recovery rate of 1,3BG.

[0120] The bottoms rate of the high boiling removal column C is preferably 25% by weight or less, more preferably 20% by weight or less, even more preferably 15% by weight or less, 10% by weight or less, 7% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, or 2% by weight or less, and can be 1% by weight or less, from the viewpoint of improving the recovery rate of 1,3BG. Furthermore, the bottoms rate of the high boiling removal column C is, for example, 0.01% by weight or more, preferably 0.1% by weight or more, 0.5% by weight or more, or 1% by weight or more, more preferably 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 6% by weight or more, 7% by weight or more, 8% by weight or more, 9% by weight or more, 10% by weight or more, or 15% by weight or more, and particularly preferably 20% by weight or more, from the viewpoint of lowering the dry point of the 1,3-butylene glycol product.

[0121] At least a portion of the liquid containing concentrated high-boiling components withdrawn from below the feed tray of high-boiling column C (hereinafter, sometimes referred to as "bottom liquid") may be recycled to a step preceding the high-boiling component removal step (dashed arrow shown below high-boiling column C in Figure 1). By recycling at least a portion of the bottom liquid to a step preceding the high-boiling component removal step, the recovery rate of 1,3BG can be improved. In this specification, the recovery rate of 1,3BG in high-boiling column C is a value (%) calculated by the following formula: {1 - [GC area % of 1,3BG in bottoms × (bottoms amount (parts) - recycled amount (parts))] / (GC area % of 1,3BG in feed solution × feed amount (parts))} × 100 Note that low-boiling and high-boiling substances may be hydrolyzed with water to produce 1,3BG, while high-boiling substances may be produced by polymerization of 1,3BG. Furthermore, trace impurities may be produced or lost, so that a material balance in the high-boiling removal tower may not always be obtained.

[0122] The recovery rate of 1,3BG in high boiler removal column C is, for example, more than 80%, preferably 85% or more, more preferably 90% or more, even more preferably 95% or more, and particularly preferably 99% or more.

[0123] Examples of processes preceding the high-boiling point removal process include an acetaldehyde polymerization process (an aldol condensation process of acetaldehyde), a reaction process (a hydrogenation process), a dealcoholization process (a low-boiling point removal process), a dehydration process, and a desalination process. Among these, since 1,3BG is produced by hydrolysis of high-boiling points, it is preferable to recycle the acetaldehyde to the acetaldehyde polymerization process (an aldol condensation process of acetaldehyde). Furthermore, 1,3BG may also be produced by hydrogenation reduction, and from this perspective, the acetaldehyde may be recycled to the hydrogenation process.

[0124] The amount of the bottoms recycled to the process prior to the high boiling point removal step can be appropriately selected within the range of the amount of the bottoms. The amount of the bottoms recycled to the process prior to the high boiling point removal step is, for example, less than 30% by weight, preferably 25% by weight or less, based on the amount charged to high boiling point removal column C. The recycled amount may be 20% by weight or less, 15% by weight or less, 10% by weight or less, 7% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, or 1% by weight or less, based on the amount charged to high boiling point removal column C. From the viewpoint of improving the 1,3BG recovery rate in the high boiling removal tower and the yield throughout the 1,3BG production process, the amount of the bottoms recycled to the steps preceding the high boiling removal tower is, for example, 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 7% by weight or more, or 10% by weight or more, and particularly preferably 20% by weight or more, relative to the amount charged to high boiling removal tower C. Note that when the amount of bottoms is minimized, 1,3BG can be recovered at a high yield without recycling to the preceding steps.

[0125] In Production Method 2 of the present disclosure, the crude 1,3-butylene glycol stream withdrawn from above the feed tray of the high boiling removal tower C can be used as a 1,3-butylene glycol product as is. Alternatively, the crude 1,3-butylene glycol stream withdrawn from above the feed tray of the high boiling removal tower C can be subjected to an alkali treatment in an alkali reactor D described below and evaporated (or distilled) in a dealkalizer E, and the overhead distillate of the dealkalizer E can be used as a 1,3-butylene glycol product.

[0126] According to Production Method 2 of the present disclosure, the acetaldehyde and crotonaldehyde contents in the high boiling removal tower feed liquid are set within specific ranges, and the reflux ratio of the high boiling removal tower is set within a specific range. This makes it possible to industrially efficiently produce high-purity 1,3-butylene glycol that is colorless and odorless (or almost colorless and odorless), is resistant to coloration and odor generation over time, and is resistant to an increase in acid concentration over time even when containing water.

[0127] In Production Method 1 of the present disclosure, the crude 1,3-butylene glycol stream withdrawn from the high boiler removal column C above the feed stage is supplied to, for example, an alkali reactor (e.g., a flow-type tubular reactor) D and subjected to a base treatment (alkali treatment). By base treatment, by-products contained in the crude 1,3-butylene glycol can be decomposed. The base is added to the alkali reactor D or to a pipe upstream thereof. The amount of base added is, for example, 0.05 to 10 wt %, preferably 0.1 to 1.0 wt %, based on the crude 1,3-butylene glycol stream to be subjected to the alkali treatment. If the amount of base added exceeds 10 wt %, the base may precipitate in the distillation column, pipes, etc., and cause blockage. Furthermore, a decomposition reaction of high-boiling compounds may occur, which may result in the generation of by-products. If the amount of base added is less than 0.05 wt %, the effect of decomposing by-products is small.

[0128] The base added to the alkaline reactor D or the piping upstream thereof is not particularly limited, but is preferably, for example, an alkali metal compound. Examples of alkali metal compounds include sodium hydroxide, potassium hydroxide, sodium (bi)carbonate, and potassium (bi)carbonate. A basic ion exchange resin can also be used as the base. From the viewpoint of reducing by-products contained in the finally obtained 1,3-butylene glycol product, sodium hydroxide and potassium hydroxide are preferred as the base. The base may be added as a solid as is, but is preferably added as an aqueous solution for operational reasons and to promote contact with the liquid to be treated. The above bases may be used alone or in combination of two or more.

[0129] The reaction temperature in the alkali reactor D is not particularly limited, but is preferably 90 to 140°C, more preferably 110 to 130°C, for example. If the reaction temperature is less than 90°C, a long reaction residence time is required, which increases the reactor capacity and is uneconomical. If the reaction temperature exceeds 140°C, the coloration of the final 1,3-butylene glycol product may increase. The reaction residence time is preferably 5 to 120 minutes, more preferably 10 to 30 minutes, for example. If the reaction residence time is less than 5 minutes, the reaction may be insufficient, and the quality of the final 1,3-butylene glycol product may deteriorate. If the reaction residence time exceeds 120 minutes, a large reactor is required, which increases the equipment cost and is therefore disadvantageous from an economic standpoint.

[0130] After leaving the alkali reactor D, the crude reaction liquid stream is optionally supplied to a dealkalizer (e.g., a thin-film evaporator) E, where the base and other components are removed from the bottom of the column by evaporation. Meanwhile, a crude 1,3-butylene glycol stream (which becomes the 1,3-butylene glycol product in Production Method 2 of the present disclosure) after debasing is obtained from the top of the dealkalizer E. The evaporator used in the dealkalizer E is preferably a gravity-flow thin-film evaporator or a forced-agitation thin-film evaporator with a short residence time, in order to minimize the thermal history of the process fluid. A demister may be installed in the space above the charge position of the dealkalizer (e.g., thin-film evaporator) E to remove droplets of the base and other components. This prevents the base and other components from being mixed into the 1,3-butylene glycol product.

[0131] In the evaporator used in the dealkalizer E, evaporation is carried out at the top of the column under a reduced pressure of, for example, 20 kPa absolute pressure or less, preferably 0.5 to 10 kPa absolute pressure. The temperature of the evaporator is preferably, for example, 90 to 120°C. The crude 1,3-butylene glycol stream containing low boiling point substances distilled from the top of the column is supplied to a product distillation column (product column) F. As described above, in Production Method 2 of the present disclosure, the distillate (corresponding to E-1) from the top of the dealkalizer E can be used as the 1,3-butylene glycol product.

[0132] The alkali reactor D and the dealkalizer E may be installed between the demineralizer B and the high boiling demineralizer C, between the demineralizer A and the demineralizer B (in this case, the demineralizer may also serve as the dealkalizer), or before the dehydrator A. Alternatively, the alkali treatment can be performed without installing the alkali reactor D and the dealkalizer E by feeding a base into the high boiling demineralizer feed line, feeding into the dehydrator feed line, or adding it to the reaction liquid after hydrogenation [and then feeding it into the dealcoholizer (low boiling demineralizer)].

[0133] In production method 1 of the present disclosure, in product column F used in the product distillation step, a feed liquid having a 1,3-butylene glycol concentration of, for example, 97.6 area % or more as determined by GC analysis is distilled, a liquid in which low-boiling point components are concentrated is distilled from above the feed stage (corresponding to "X-6" in FIG. 1), and 1,3-butylene glycol is withdrawn from below the feed stage (corresponding to "Y" in FIG. 1). The withdrawn 1,3-butylene glycol can be used as a 1,3-butylene glycol product.

[0134] For example, a perforated plate column or a bubble cap column can be used as product column F. However, a packed column with low pressure drop, such as Sulzer Packing or Melapak (both trade names of Sumitomo Heavy Industries, Ltd.), is more preferable. This is because 1,3-butylene glycol and trace amounts of impurities contained therein undergo thermal decomposition at high temperatures (e.g., 150°C or higher), producing low-boiling substances that cause coloration, and therefore the distillation temperature must be low. Furthermore, a long thermal history (residence time) of 1,3-butylene glycol can have a similar effect. Therefore, the reboiler used should be one with a short residence time for the process fluid, such as a gravity-flow thin-film evaporator or a forced-agitation thin-film evaporator.

[0135] The number of theoretical plates in product column F is, for example, 1 to 100, preferably 2 to 90, 3 to 80, 4 to 70, 5 to 60, 8 to 50, or 10 to 40, and more preferably 15 to 30. The feed position of the charge liquid is, for example, 10 to 90%, preferably 20 to 80%, more preferably 30 to 70%, and even more preferably 40 to 60% of the height of the column downward from the top of the column. In the distillation in product distillation column F, the pressure (absolute pressure) at the top of the column is, for example, 20 kPa or less, preferably 0.1 to 10 kPa, more preferably 0.3 to 8 kPa, and even more preferably 0.5 to 5 kPa.

[0136] In Figure 1, the feed to product tower F is the liquid obtained by condensing the top vapor of dealkalization tower E in condenser E-1, but the top vapor from dealkalization tower E may also be fed directly to product tower F.

[0137] The concentration of 1,3-butylene glycol in the feed liquid (1,3-butylene glycol feed liquid) to product column F is 97.6% or more, preferably 97.8% or more, more preferably 98% or more, even more preferably 98.2% or more (e.g., 98.4% or more, 98.6% or more, or 98.8% or more), and particularly preferably 99% or more (e.g., 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, 99.6% or more, 99.7% or more, 99.8% or more, or 99.9% or more).

[0138] The concentration of 1,3-butylene glycol in the liquid charged to product column F can be improved, for example, by adjusting the distillation conditions of dehydrating column A, by providing a dealcoholization column (low boiling column) upstream of dehydrating column A and adjusting the distillation conditions therefor, or by adjusting the distillation conditions of high boiling column C. For example, the purity of 1,3-butylene glycol in the liquid charged to product column F can be increased by increasing the reflux ratio of the dealcoholization column (low boiling column), dehydrating column A, and / or high boiling column C, or by increasing the number of plates.

[0139] The concentration of 1,3-butylene glycol in the liquid charged to the product column F is the ratio (area %) of the area of ​​the 1,3-butylene glycol peak to the total peak area in gas chromatography analysis under the following conditions. (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[0140] In the production method 1 of the present disclosure, the content of acetaldehyde in the feed liquid to product column F is 500 ppm or less, preferably 205 ppm or less (e.g., 200 ppm or less), more preferably 150 ppm or less, even more preferably 120 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, or 10 ppm or less, and particularly preferably 5 ppm or less, and may be less than 2 ppm. The crotonaldehyde content in the feed liquid to product column F is 200 ppm or less, preferably 150 ppm or less, more preferably 130 ppm or less, even more preferably 110 ppm or less, 100 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, or 3 ppm or less, and particularly preferably 2 ppm or less, and may even be less than 1 ppm. The acetaldehyde content and crotonaldehyde content in the feed liquid to product column F can be reduced, for example, by providing a dealcoholization column (low boiling point removal column) or a dehydration column upstream of product column F and adjusting the distillation conditions of the dealcoholization column (low boiling point removal column) or the dehydration column. For example, the acetaldehyde content and crotonaldehyde content in the feed liquid to product column F can be reduced by increasing the reflux ratio, number of stages, and distillate rate of the dealcoholization column (low boiling point removal column) and the dehydration column. The acetaldehyde content and crotonaldehyde content in the feed liquid to product column F can be reduced by increasing the reaction temperature, the residence time, or the amount of base added in the alkali reaction step. The acetaldehyde content and crotonaldehyde content in the feed liquid to product column F can be quantified by GC-MS analysis (gas mass spectrometry).

[0141] In Production Method 1 of the present disclosure, the water content in the feed liquid to product column F is 0.7% by weight or less, preferably 0.6% by weight or less, 0.5% by weight or less, 0.4% by weight or less, 0.3% by weight or less, or 0.2% by weight or less, and particularly preferably 0.1% by weight or less. The water content in the feed liquid to product column F can be reduced by adjusting the distillation conditions of the dehydrating column A. For example, the water concentration in the feed liquid to product column F can be reduced by increasing the reflux ratio, number of stages, or distillate rate of the dehydrating column A. The water content in the feed liquid to product column F can be quantified using a Karl Fischer moisture content meter.

[0142] The content of low-boiling components (excluding water) in the liquid fed to product column F is, for example, 1.8% or less, preferably 1.6% or less, more preferably 1.4% or less, even more preferably 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less, and particularly preferably 0.1% or less. The content of low-boiling components (excluding water) in the liquid fed to product column F is the ratio (area %) of the total area of ​​peaks having a shorter retention time than the peak of 1,3-butylene glycol to the total peak area in gas chromatography analysis under the above conditions. The content of low-boiling components (excluding water) in the liquid fed to product column F can be reduced, for example, by providing a dealcoholization column (low-boiling column) upstream of product column F and adjusting the distillation conditions of the dealcoholization column (low-boiling column). For example, by increasing the reflux ratio, number of stages, and distillate rate of the dealcoholization tower (low boiling point removal tower), the concentration of low boiling point components (excluding water) in the feed liquid to product tower F can be reduced.

[0143] The content of high-boiling components (excluding water) in the liquid fed to product column F is, for example, 1.8% or less, preferably 1.6% or less, more preferably 1.4% or less, even more preferably 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less, and particularly preferably 0.1% or less. The content of high-boiling components excluding water (also referred to as "high boilers" or "high boilers") in the liquid fed to product column F is the ratio (area %) of the total area of ​​peaks having a longer retention time than the peak of 1,3-butylene glycol to the total peak area in gas chromatography analysis under the above conditions. The content of high-boiling components (excluding water) in the liquid fed to product column F can be reduced, for example, by adjusting the distillation conditions of the high-boiling separation column. For example, the concentration of high boiling point components (excluding water) in the liquid fed to the product column F can be reduced by increasing the reflux ratio, number of stages, and bottoms rate of the high boiling separation column.

[0144] In Production Method 1 of the present disclosure, the reflux ratio in product column F [amount refluxed to product column / amount distilled from product column (amount discharged outside the distillation column)] is, from the viewpoint of increasing the initial boiling point of the 1,3-butylene glycol product, 0.3 or more, preferably 0.4 or more, more preferably 0.5 or more, 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 or more, or 50 or more, and particularly preferably 400 or more (e.g., 500 or more). The upper limit of the reflux ratio in product column F is, for example, 700 or 1000 from the viewpoint of energy costs.

[0145] In Production Method 1 of the present disclosure, the distillate rate from product column F is, for example, less than 30% by weight, preferably 29% by weight or less, more preferably 28% by weight or less, even more preferably 27% by weight or less, 26% by weight or less, 25% by weight or less, 24% by weight or less, 23% by weight or less, 22% by weight or less, 21% by weight or less, 20% by weight or less, 19% by weight or less, 18% by weight or less, 17% by weight or less, 16% by weight or less, 15% by weight or less, 12% by weight or less, 10% by weight or less, 8% by weight or less, 5% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, 0.8% by weight or less, or 0.6% by weight or less, and particularly preferably 0.4% by weight or less, from the viewpoint of improving the recovery rate of 1,3-butylene glycol. The distillate yield refers to the ratio (by weight) of the amount of liquid extracted from above the feed tray of product column F (e.g., from the top of the column) to the amount charged to product column F (including the recycled amount if recycled to the previous process described below).

[0146] At least a portion of the liquid (hereinafter sometimes referred to as "distillate") in which low boiling components are concentrated and which is withdrawn from above the feed tray of product column F may be recycled to a step preceding the product distillation step (the dashed arrow shown to the right of product column F in FIG. 1). By recycling at least a portion of the distillate to a step preceding the product distillation step, the recovery rate of 1,3-butylene glycol can be improved.

[0147] Examples of the process prior to the product distillation process include a dehydration process, a dealcoholization process (low boiling point removal process), etc. The dealcoholization process (low boiling point removal process) is preferably performed before the dehydration process.

[0148] The amount of the distillate recycled to the process prior to the product distillation step can be appropriately selected within the range of the amount of the distillate. The amount of the distillate recycled to the process prior to the product distillation step is, for example, less than 30% by weight relative to the amount charged to the product column F. From the viewpoint of improving the 1,3BG recovery rate in the product column and the yield throughout the process, the amount of the distillate recycled to the process prior to the product distillation step is, for example, 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 1.5% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 7% by weight or more, or 10% by weight or more, and particularly preferably 20% by weight or more.

[0149] In production method 1 of the present disclosure, by setting the contents of acetaldehyde and crotonaldehyde in the feed liquid to product column F to not more than specific values ​​and setting the reflux ratio in product column F within a specific range, it is possible to industrially efficiently produce high-purity 1,3-butylene glycol that is colorless and odorless (or almost colorless and odorless), is resistant to coloration and odor generation over time, and is resistant to an increase in acid concentration over time even when containing water.

[0150] The recovery rate of 1,3BG in product column F is, for example, more than 80%, preferably 85% or more, more preferably 90% or more, even more preferably 95% or more, and particularly preferably 99% or more.

[0151] In this specification, the recovery rate of 1,3BG in product tower F is a value (%) calculated by the following formula. {1 - [GC area % of 1,3BG in the distillate × (distillate amount (parts) - recycled amount (parts))] / (GC area % of 1,3BG in the feed solution × feed amount (parts))} × 100 As mentioned above, low-boiling and high-boiling substances may be hydrolyzed with water to produce 1,3BG, while high-boiling substances may be produced by polymerization of 1,3BG. Therefore, the material balance in the product column may not always be achieved.

[0152] Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, each configuration and their combinations in each embodiment are merely examples, and additions, omissions, and other modifications of configurations are possible as appropriate within the scope of the gist of this disclosure. The present disclosure is not limited by the embodiments, but is limited only by the scope of the claims. [Example]

[0153] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples. Note that "parts" used in the examples refer to "parts by weight" unless otherwise specified. Gas chromatography analysis (GC analysis), measurement of initial boiling point, and measurement of water content were performed by the methods described below.

[0154] [Example 1] The method for producing 1,3-butylene glycol will be described with reference to FIG. 100 parts of an acetaldol solution containing 30% by weight of water as a raw material (a mixed solution of 69 parts of acetaldol and 29 parts of water, containing a total of 2 parts of low-boiling and high-boiling impurities, and less than 0.1 parts of Na salt) were charged into a liquid-phase hydrogen reduction reactor with 10 parts of hydrogen, and 15 parts of Raney nickel were added as a catalyst. The reactor was maintained at 120°C and 10 MPa (gauge pressure) to carry out liquid-phase hydrogen reduction. After separating the catalyst from the liquid after the reaction, the liquid was neutralized with caustic soda to obtain crude 1,3-butylene glycol (1) containing low-boiling impurities and water.

[0155] The acetaldehyde solution containing 30% by weight of water used as a raw material was produced by stirring acetaldehyde and water in the presence of 100 ppm by weight of NaOH at 30°C for a residence time of 10 hours to dimerize acetaldehyde [acetaldehyde polymerization process (acetaldehyde aldol condensation process)].

[0156] Crude 1,3-butylene glycol (1) (corresponding to "X-1" in Figure 1) was charged to dehydration column A. The concentration of 1,3-butylene glycol in the charge to dehydration column A was 56 wt%, the concentration of water was 40 wt%, the content of acetaldehyde (AD) was 130 ppm, the content of crotonaldehyde (CR) was 89 ppm, and in the GC analysis described below, the total area ratio of impurity peaks with a shorter retention time (RT) than 1,3-butylene glycol was 3%, and the total area ratio of impurity peaks with a longer retention time than the 1,3-butylene glycol peak was 1%. In dehydration column A, distillation was performed under conditions of a column top pressure of 10 kPa (absolute pressure) and a reflux ratio of 1. Water was extracted from the top of the column, and 43 parts (distillate) per 100 parts of the charge was discharged and removed outside the system (corresponding to "X-2" in Figure 1). From the bottom of the column, crude 1,3-butylene glycol (2) was obtained, which had a 1,3-butylene glycol concentration of 96.9 GC area %, water of 0.9 wt %, a total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol of 0.8%, a total area ratio of peaks having longer retention times than 1,3-butylene glycol peaks of 2.3%, an acetaldehyde content of 18 ppm, and a crotonaldehyde content of 17 ppm in a GC analysis described below.

[0157] Next, crude 1,3-butylene glycol (2) was charged into demineralizer B. In demineralizer B, salts, high boiling point materials, and a portion of 1,3-butylene glycol were discharged as evaporation residue from the bottom of the column (corresponding to "X-3" in Figure 1). The amount of evaporation residue discharged was 5 parts per 100 parts of the charged liquid. Meanwhile, crude 1,3-butylene glycol (3) containing 1,3-butylene glycol, low boiling point materials, and a portion of the high boiling point materials was obtained from the top of the column.

[0158] Next, the crude 1,3-butylene glycol (3) was charged into high boiling separation column C. In high boiling separation column C, distillation was carried out under conditions of a column top pressure of 5 kPa (absolute pressure) and a reflux ratio of 0.05, and high boiling point materials and a portion of 1,3-butylene glycol were discharged from the column bottom (corresponding to "X-4" in Figure 1). The amount of the discharged material from the column bottom was 20 parts per 100 parts of the charged liquid. Meanwhile, 80 parts of crude 1,3-butylene glycol (4) containing low boiling point materials was obtained as a distillate from the column top.

[0159] Next, the crude 1,3-butylene glycol (4) was charged into an alkaline reactor D. At this time, a 20 wt % aqueous solution of caustic soda was added so that the concentration of caustic soda in the charged liquid was 0.1 wt %. The reaction temperature in the alkaline reactor D was maintained at 120°C, and the reaction was carried out for a residence time of 20 minutes.

[0160] Next, the crude reaction liquid discharged from the alkali reactor D was charged into a dealkalizer E. In the dealkalizer E, caustic soda, high boiling point substances, and a portion of 1,3-butylene glycol were discharged from the bottom of the column (corresponding to "X-5" in Figure 1). The amount of the liquid discharged from the bottom of the column was 10 parts per 100 parts of the charged liquid. Meanwhile, 90 parts of crude 1,3-butylene glycol (5) containing 1,3-butylene glycol and low boiling point substances was obtained from the top of the column. The crude 1,3-butylene glycol (5) containing 1,3-butylene glycol and low boiling point substances was subjected to water content measurement, GC analysis, and GC-MS analysis. As a result, the water concentration was 1 wt %, the area ratio of 1,3-butylene glycol was 99%, the total area ratio of impurity peaks having a shorter retention time than 1,3-butylene glycol was 0.4%, the total area ratio of impurity peaks having a longer retention time than 1,3-butylene glycol was 0.6%, the acetaldehyde content was 20 ppm, and the crotonaldehyde content was 9 ppm.

[0161] Next, crude 1,3-butylene glycol (5) was charged into product column F. In product column F, 10 parts of low boiling point materials and a portion of 1,3-butylene glycol were distilled from the top of the column relative to 100 parts of the charged liquid (corresponding to "X-6" in Figure 1), and the entire amount was discharged outside the system. The column was operated at a reflux ratio (reflux amount / distillate amount) of 0.5, and 90 parts of 1,3-butylene glycol product were obtained from the bottom of the column (distillate amount: 10 parts) (corresponding to "Y" in Figure 1).

[0162] The resulting 1,3-butylene glycol product was subjected to measurement of the initial boiling point, moisture content, GC analysis, and GC-MS analysis. The initial boiling point was 203.3°C, the dry point was 209°C, the moisture content was 0.2% by weight, the area ratio of 1,3-butylene glycol was 99.2%, the total area ratio of impurity peaks with shorter retention times than 1,3-butylene glycol was 0.08%, the total area ratio of impurity peaks with longer retention times than 1,3-butylene glycol was 0.7%, the acetaldehyde content was 1.5 ppm, and the crotonaldehyde content was 0.9 ppm. The potassium permanganate test value was 35 minutes. The recovery rate of 1,3-butylene glycol in product column F was 90%.

[0163] [Example 2] The same operation as in Example 1 was carried out, except that the reflux ratio of dehydrating tower A was changed to 50. 1,3-butylene glycol product was obtained from the bottom of product tower F. Note that, due to the change in the conditions of dehydrating tower A, the composition of the dehydrating tower bottoms changed, and the compositions of the charged liquids of high boiling removal tower C and product tower F each changed, resulting in a change in the quality of the product. The resulting 1,3-butylene glycol product was subjected to measurement of the initial boiling point, moisture content, GC analysis, and GC-MS analysis. The initial boiling point was 206.7°C, the dry point was 208.9°C, the moisture content was 0.1% by weight, the area ratio of 1,3-butylene glycol was 99.3%, the total area ratio of impurity peaks with shorter retention times than 1,3-butylene glycol was 0.05%, the total area ratio of impurity peaks with longer retention times than 1,3-butylene glycol was 0.7%, the acetaldehyde content was 0.7 ppm, and the crotonaldehyde content was 0.7 ppm. The potassium permanganate test value was 45 minutes. The recovery rate of 1,3-butylene glycol in product column F was 90%.

[0164] [Examples 3 to 27] Dehydration column A, high-boiling dehydration column C, and product column F were operated under the conditions shown in Tables 1 and 2. In Examples 4 to 22 and 24 to 27, the distillate from product column F was entirely recycled to the hydrogen reduction reactor. In Example 23, product column F was not used, and the overhead distillate from dealkalization column E (a demister was installed in the space above the charging position) was used as the 1,3-butylene glycol product. The concentration of the aqueous caustic soda solution in alkali reactor D was increased by 1.5 times, and the amount of aqueous caustic soda solution added was half that of Example 1, thereby minimizing the increase in moisture content due to the alkali treatment. If the alkali concentration of the aqueous caustic soda solution is too high, crystals will precipitate, so it is preferable to heat it to 40°C or higher. In Table 2, the column for "Product column F bottoms" for Example 23 lists the composition and physical properties of the overhead distillate from dealkalization column E. In Example 16, 8 parts of the 10 parts of the high boiling column bottoms were recycled to the hydrogenation step, and 2 parts were discharged outside the system. In Example 25, the pressure of the hydrogenation reaction was reduced to 7 MPaG (gauge pressure). As a result, the acetaldehyde and crotonaldehyde contents in the dehydrating column feed were high. In Example 26, the reflux ratio of the dehydrating column was reduced to 0.3, the purity of 1,3-butylene glycol in the product column feed was reduced, and the reflux ratio of the product column was increased to 20. In Example 27, the pressure of the hydrogenation reaction was increased to 40 MPaG (gauge pressure) (the remaining conditions were the same as in Example 18).

[0165] [Comparative Example 1] The reflux ratio of dehydration tower A was changed to 0.5, the distillate volume to 42 parts, the reflux ratio of high boiling tower C was changed to 0.02, the reflux ratio of product tower F was changed to 0.05, and the distillate volume to 20 parts. 80 parts of 1,3-butylene glycol product was obtained from the bottom of product tower F in the same manner as in Example 1. The initial boiling point of the obtained 1,3-butylene glycol product was 193.2 ° C, the dry point was 210.3 ° C, the water concentration was 0.6 wt%, the area ratio of 1,3-butylene glycol was 98.3%, the total area ratio of impurity peaks with shorter retention times than 1,3-butylene glycol was 0.2%, the total area ratio of impurity peaks with longer retention times than 1,3-butylene glycol was 1.5%, the acetaldehyde content was 5 ppm, and the crotonaldehyde content was 4 ppm. The potassium permanganate test value was 0 min. The recovery rate of 1,3-butylene glycol in product tower F was 80%.

[0166] Comparative Example 2 The feed composition of the dehydration tower A was changed, the reflux ratio was changed to 0.5, the distillate amount was changed to 32 parts, the reflux ratio of the high boiling tower C was changed to 0.02, the reflux ratio of the product tower F was changed to 0.05, and the distillate amount was changed to 20 parts. Except for this, 80 parts of 1,3-butylene glycol product was obtained from the bottom of the product tower F in the same manner as in Example 1. The initial boiling point of the obtained 1,3-butylene glycol product was 199.0 ° C., the dry point was 210.1 ° C., the water concentration was 0.4 wt%, the area ratio of 1,3-butylene glycol was 98.5%, the total area ratio of impurity peaks with shorter retention times than 1,3-butylene glycol was 0.1%, the total area ratio of impurity peaks with longer retention times than 1,3-butylene glycol was 1.4%, the acetaldehyde content was 4 ppm, and the crotonaldehyde content was 2 ppm. The potassium permanganate test value was 5 minutes. The recovery rate of 1,3-butylene glycol in product column F was 80%.

[0167] Comparative Example 3 The feed composition of the dehydration tower A was changed, the reflux ratio was changed to 0.5, the distillate amount was changed to 32 parts, the reflux ratio of the high boiling tower C was changed to 0.02, the reflux ratio of the product tower F was changed to 0.05, and the distillate amount was changed to 30 parts. Except for this, 70 parts of 1,3-butylene glycol product was obtained from the bottom of the product tower F in the same manner as in Example 1. The initial boiling point of the obtained 1,3-butylene glycol product was 203.0 ° C., the dry point was 210.2 ° C., the water concentration was 0.2 wt%, the area ratio of 1,3-butylene glycol was 98.4%, the total area ratio of impurity peaks with shorter retention times than 1,3-butylene glycol was 0.1%, the total area ratio of impurity peaks with longer retention times than 1,3-butylene glycol was 1.5%, the acetaldehyde content was 2 ppm, and the crotonaldehyde content was 1.3 ppm. The potassium permanganate test value was 30 minutes. The recovery rate of 1,3-butylene glycol in product column F was 70%.

[0168] Comparative Example 4 The feed composition of dehydration tower A was changed, the distillate volume was changed to 23 parts, the reflux ratio of high boiling tower C was changed to 0.02, the reflux ratio of product tower F was changed to 0.1, and the distillate volume was changed to 20 parts. 80 parts of 1,3-butylene glycol product was obtained from the bottom of product tower F in the same manner as in Example 1. The initial boiling point of the obtained 1,3-butylene glycol product was 203.1 ° C, the dry point was 209.5 ° C, the water concentration was 0.2 wt%, the area ratio of 1,3-butylene glycol was 98.8%, the total area ratio of impurity peaks with shorter retention times than 1,3-butylene glycol was 0.1%, the total area ratio of impurity peaks with longer retention times than 1,3-butylene glycol was 1.1%, the acetaldehyde content was 2 ppm, and the crotonaldehyde content was 1.3 ppm. The potassium permanganate test value was 30 minutes. The recovery rate of 1,3-butylene glycol in product tower F was 80%.

[0169] [Gas Chromatography Analysis] Gas chromatography analysis of the target 1,3-butylene glycol product was performed under the following conditions. A chart of the gas chromatography analysis of the 1,3-butylene glycol product in Example 12 is shown in Figure 2. A chart of the gas chromatography analysis of the 1,3-butylene glycol product in Comparative Example 2 is shown in Figure 3. (Gas chromatographic analysis conditions) Analytical equipment: Shimadzu GC2010 Analytical column: A column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) ("Agilent J&W GC Column - DB-1", manufactured by Agilent Technologies, Inc.) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction and temperature: Split sample introduction, 250°C Split gas flow rate and carrier gas: 23 mL / min, helium Column gas flow rate and carrier gas: 1 mL / min, helium Detector and temperature: Flame ionization detector (FID), 280°C Injected sample: 0.2 μL of 80 wt% 1,3-butylene glycol product aqueous solution

[0170] [Initial boiling point and dry point measurement] The test was carried out in accordance with the test method specified in the atmospheric distillation test method of JIS K2254 "Petroleum products - Distillation test method."

[0171] [Moisture measurement] The measurement was carried out using a Karl Fischer moisture content analyzer.

[0172] [GC-MS analysis] Analyzer: Agilent 6890A-GC / 5973A-MSD Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Ion source temperature: EI 230℃, CI 250℃ Q pole temperature: 150℃ Sample: Ready for analysis

[0173] [Potassium permanganate test] In this specification, the potassium permanganate test value (PMT) is a value measured in accordance with the procedure of the visual colorimetric method of JIS K1351 (1993).

[0174] [Temporal coloration test 1] The target 1,3-butylene glycol products were placed in wide-mouth bottles, sealed, and held in a thermostatic chamber set to 180°C for 3 hours. Using a colorimeter ("ZE6000" manufactured by Nippon Denshoku Industries Co., Ltd.) and a quartz cell with an optical path length of 10 mm, the Hazen color number (APHA) of the 1,3-butylene glycol products after holding at 180°C for 3 hours was measured. The Hazen color number (APHA) of the 1,3-butylene glycol products before the test was also measured in the same way.

[0175] [Temporal coloration test 2] The target 1,3-butylene glycol products were placed in wide-mouth bottles, which were then sealed and kept in a thermostatic chamber set to 100°C for 75 days. Using a colorimeter ("ZE6000" manufactured by Nippon Denshoku Industries Co., Ltd.) and a quartz cell with an optical path length of 10 mm, the Hazen color number (APHA) of the 1,3-butylene glycol products after 75 days of storage at 100°C was measured.

[0176] [Water addition heating test (acid concentration analysis)] The target 1,3-butylene glycol product was prepared into a 90 wt % aqueous solution, and after holding at 100°C for one week, the sample was subjected to acid concentration analysis using the following method. In addition, the acid concentration of the 1,3-butylene glycol product before the test was also analyzed using the following method. (Acid concentration analysis) Measurements were performed by potentiometric titration using an automatic potentiometric titrator (AT-510, manufactured by Kyoto Electronics Manufacturing Co., Ltd.). 50 g of sample was diluted with 50 g of distilled water, and while stirring, 0.01 N aqueous sodium hydroxide solution was titrated from a burette until the automatic end point stopped. The acid concentration (acid content) in terms of acetic acid was then calculated using the following formula: Acid concentration (wt%) = titration volume (ml) × F × A × (100 / sample volume (g)) F: 1.0 (factor of 0.01N sodium hydroxide solution) A: 0.0006 (the number of grams of acetic acid equivalent to 1 ml of sodium hydroxide solution)

[0177] [Odor test] The target 1,3-butylene glycol product (100 ml) was placed in a wide-mouth reagent bottle (internal volume: 100 ml), sealed, and left to stand at room temperature for a while (approximately 120 minutes), after which the stopper was opened and the bottle was transferred to a 300 ml wide-mouth beaker, and 100 ml of pure water was added to make a total of 200 ml. The bottle was then shaken by hand to mix, after which the odor was immediately smelled and scored according to the following evaluation criteria. Similar odor tests were also conducted on the samples after the above-mentioned Time-Dependent Coloration Test 1 and the samples after the above-mentioned Water-Added Heating Test. 1: No smell 2: Slight odor 3: You can clearly smell it

[0178] [Discussion of results] The results of the above comparative examples and examples are shown in Tables 1, 2 and 3.

[0179] [Table 1]

[0180] [Table 2]

[0181] [Table 3]

[0182] From Comparative Example 1, Comparative Example 2, Example 1, Example 5, and Example 7, it can be seen that the lower the contents of acetaldehyde, crotonaldehyde, and other impurities (quantitation limit 10 ppm) detected by gas chromatography analysis, and methyl vinyl ketone, acetone, butylaldehyde, acetaldol, the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (3), the compound represented by formula (4), and the compound represented by formula (5) detected by GC-MS analysis, the better the long-term storage stability in terms of coloration, acid concentration, and odor.

[0183] The same is true for Examples 7, 12, and 18. From Examples 12 and 18, it was found that reducing the content of methyl vinyl ketone, acetone, butyl aldehyde, acetaldol, and the compound represented by formula (1), which have lower boiling points than 1,3BG, as well as reducing the content of the compound represented by formula (2), formula (3), formula (4), and formula (5), which have higher boiling points than 1,3BG, is effective in improving long-term stability. However, reducing not only the content of these impurities but also the total content of acetaldehyde, crotonaldehyde, and other impurities (quantitation limit 10 ppm) detected by gas chromatography analysis is most effective for improving the long-term quality of 1,3BG products, and Example 7 significantly improved the stability of product quality. Overall, there is no clear correlation between the content of impurities (quantitation limit around 10 ppm) detected by gas chromatography analysis other than 1,3BG and the content of impurities less than 10 ppm detected by GC-MS analysis, from methyl vinyl ketone to the compound represented by formula (5). This is thought to be the result of subtle fluctuations in the concentration of each component depending on the reaction conditions and individual distillation conditions.

[0184] In Example 24, the water content of the dehydration tower feed liquid was very high, but the trends were the same as those described above. The relationship between the behavior of all impurities and the APHA and acid concentration (acid content) showed similar trends to those in Example 7.

[0185] In Example 26, the concentration of 1,3-butylene glycol in the product column feed liquid is reduced, but it is clear that the quality of the 1,3BG product can be maintained by maintaining a relatively high reflux ratio in the product column.

[0186] Examples 18 and 27 show that the quality of the 1,3BG product can be further improved by increasing the hydrogenation pressure, completely reacting unsaturated compounds such as aldehydes and olefins, and acetals in the reaction system, and further adjusting the distillation conditions in each distillation column.

[0187] In summary, the configuration of the present disclosure and its variations are noted below. [1] A 1,3-butylene glycol product in which the content of at least one of the following eight contents is less than 8 ppm (or 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less): the content of methyl vinyl ketone, the content of acetone, the content of butyraldehyde, the content of acetaldol, the content of a compound represented by the following formula (1), the content of a compound represented by the following formula (2), the content of a compound represented by the following formula (3), and the total content of a compound represented by the following formula (4) and a compound represented by the following formula (5): [ka] [2] The 1,3-butylene glycol product according to [1], wherein the contents of two (or three, four, five, six, seven, or eight) of the eight contents of methyl vinyl ketone, acetone, butyl aldehyde, acetaldol, the compound represented by the following formula (1), the compound represented by the following formula (2), the compound represented by the following formula (3), and the total content of the compound represented by the following formula (4) and the compound represented by the following formula (5) are each less than 8 ppm (or 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). [3] The 1,3-butylene glycol product according to [1] or [2], wherein the contents of at least four (four, five, six, seven, or eight) of the eight contents of methyl vinyl ketone, acetone, butyl aldehyde, acetaldol, the compound represented by the following formula (1), the compound represented by the following formula (2), the compound represented by the following formula (3), and the total content of the compound represented by the following formula (4) and the compound represented by the following formula (5) are each less than 8 ppm (or 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). [4] The 1,3-butylene glycol product according to any one of [1] to [3] above, in which the sum of the content of methyl vinyl ketone, the content of acetone, the content of butyraldehyde, the content of acetaldol, the content of the compound represented by formula (1), the content of the compound represented by formula (2), the content of the compound represented by formula (3), the content of the compound represented by formula (4), and the content of the compound represented by formula (5) is less than 71 ppm (or 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 18 ppm or less, 16 ppm or less, 14 ppm or less, 12 ppm or less, 10 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). [5] The sum of the content of methyl vinyl ketone, the content of acetone, the content of butyl aldehyde, the content of acetaldol, and the content of the compound represented by formula (1) is less than 47 ppm (or 40 ppm or less, 30 ppm or less, 25 ppm or less, 20 ppm or less, 18 ppm or less, 16 ppm or less, 14 ppm or less, 12 ppm or less, 10 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less), and the content of the compound represented by formula (2) is The 1,3-butylene glycol product according to any one of [1] to [4], wherein the total content of the compound represented by formula (3), the compound represented by formula (4), and the compound represented by formula (5) is less than 24 ppm (or 20 ppm or less, 18 ppm or less, 16 ppm or less, 14 ppm or less, 13 ppm or less, 12 ppm or less, 11 ppm or less, 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). [6] The 1,3-butylene glycol product according to any one of [1] to [5], having an acetaldol content of less than 8 ppm (or 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). [7] The 1,3-butylene glycol product according to any one of [1] to [6], wherein the content of at least the compound represented by formula (3) is less than 8 ppm (or 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). [8] The 1,3-butylene glycol product according to any one of [1] to [7] above, in which the total content of methyl vinyl ketone, acetone, and butyraldehyde is 24 ppm or less (or 20 ppm or less, 18 ppm or less, 16 ppm or less, 14 ppm or less, 12 ppm or less, 11 ppm or less, 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, or 0.5 ppm or less). [9] The 1,3-butylene glycol product according to any one of [1] to [8] above, wherein the total content of the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (4), and the compound represented by formula (5) is 24 ppm or less.

[10] The 1,3-butylene glycol product according to any one of [1] to [9], having an acetaldehyde content of less than 4 ppm (or less than 2 ppm, 1.8 ppm or less, 1.7 ppm or less, 1.5 ppm or less, 1.4 ppm or less, 1.3 ppm or less, 1.2 ppm or less, 1.1 ppm or less, 1.0 ppm or less, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.3 ppm or less, or 0.2 ppm or less).

[11] The 1,3-butylene glycol product according to any one of [1] to

[10] , having a crotonaldehyde content of less than 2 ppm (or less than 1.2 ppm, 1.0 ppm or less, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.4 ppm or less, 0.3 ppm or less, 0.2 ppm or less, or 0.1 ppm or less).

[12] The 1,3-butylene glycol product according to any one of [1] to

[11] above, having an acid concentration (acetic acid equivalent) of less than 11 ppm (or 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, or 3 ppm or less), and having an acid concentration (acetic acid equivalent) of less than 23 ppm (or 20 ppm or less, 19 ppm or less, 18 ppm or less, 17 ppm or less, 16 ppm or less, 15 ppm or less, 14 ppm or less, 13 ppm or less, 12 ppm or less, 11 ppm or less, 10 ppm or less, 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, or 2 ppm or less) after a 90 wt % aqueous solution is kept at 100°C for one week.

[13] The 1,3-butylene glycol product according to any one of [1] to

[12] above, having an APHA of 6 or less (or 5 or less, 4 or less, 3 or less, or 2 or less), and having an APHA of 78 or less (or 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 20 or less, 18 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, or 7 or less) after being kept in an air atmosphere at 180°C for 3 hours.

[14] The 1,3-butylene glycol product according to any one of [1] to

[13] above, having an APHA of 42 or less (or 35 or less, 30 or less, 25 or less, 20 or less, 18 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less) after being kept at 100°C for 75 days in an air atmosphere.

[15] The 1,3-butylene glycol product according to any one of [1] to

[14] above, having an initial boiling point higher than 203°C (or 204°C or higher, 205°C or higher, 206°C or higher, 207°C or higher, or 208°C or higher), and / or a dry point of 209°C or lower.

[16] The 1,3-butylene glycol product according to any one of [1] to

[15] above, having a potassium permanganate test value of 30 minutes or more (or more than 30 minutes, 32 minutes or more, 35 minutes or more, 40 minutes or more, 50 minutes or more, or 60 minutes or more).

[17] The 1,3-butylene glycol product according to any one of [1] to

[16] above, in which the area ratio (GC area ratio) of the 1,3-butylene glycol peak is higher than 98.7% (or 98.8% or more, 98.9% or more, 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, 99.6% or more, 99.7% or more, or 99.8% or more) in gas chromatography analysis (GC analysis) under the following conditions: (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[18] The 1,3-butylene glycol product according to any one of [1] to

[17] above, wherein in gas chromatography analysis (GC analysis) under the above conditions, the total area ratio of peaks having shorter retention times than the peak of 1,3-butylene glycol is less than 0.3% (or is 0.28% or less, 0.25% or less, 0.23% or less, 0.2% or less, 0.17% or less, 0.15% or less, 0.12% or less, 0.1% or less, 0.07% or less, 0.04% or less, 0.03% or less, 0.02% or less, 0.01% or less, 0.007% or less, 0.005% or less, or 0.002% or less).

[19] The 1,3-butylene glycol product according to any one of [1] to

[18] , wherein in gas chromatography analysis (GC analysis) under the above conditions, the total area ratio of peaks having longer retention times than the peak of 1,3-butylene glycol is less than 1.2% (or is 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, or 0.1% or less).

[20] The 1,3-butylene glycol product according to any one of [1] to

[19] , having a water content of less than 0.4% by weight (or 0.3% by weight or less, 0.2% by weight or less, 0.1% by weight or less, 0.07% by weight or less, 0.05% by weight or less, 0.03% by weight or less, 0.02% by weight or less, 0.01% by weight or less, or 0.005% by weight or less).

[21] A moisturizer containing the 1,3-butylene glycol product according to any one of [1] to

[20] above.

[22] The moisturizing agent according to

[21] , wherein the content of the 1,3-butylene glycol product according to any one of [1] to

[20] is 10% by weight or more (or 30% by weight or more, 50% by weight or more, 80% by weight or more, or 90% by weight or more).

[23] A cosmetic comprising the moisturizer according to

[21] or

[22] above.

[24] The cosmetic according to the above

[23] , wherein the content of the 1,3-butylene glycol product according to any one of the above [1] to

[20] is 0.01 to 40% by weight (or 0.1 to 30% by weight, 0.2 to 20% by weight, 0.5 to 15% by weight, or 1 to 10% by weight).

[25] The cosmetic according to

[23] or

[24] above, which is a skin cosmetic, a hair cosmetic, a sunscreen cosmetic, or a makeup cosmetic.

[26] A method for producing 1,3-butylene glycol, in which purified 1,3-butylene glycol is obtained from a reaction crude liquid containing 1,3-butylene glycol, The process includes a dehydration process for removing water by distillation, a high boiling point removal process for removing high boiling point components by distillation, and a product distillation process for obtaining purified 1,3-butylene glycol. In the product column used in the product distillation step, the acetaldehyde content is 500 ppm or less (or 205 ppm or less, 200 ppm or less, 150 ppm or less, 120 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, or less than 2 ppm), and the crotonaldehyde content is 500 ppm or less (or 205 ppm or less, 200 ppm or less, 150 ppm or less, 120 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, or less than 2 ppm). The content is 200 ppm or less (or 150 ppm or less, 130 ppm or less, 110 ppm or less, 100 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or less than 1 ppm), and the water content is 0.7% by weight or less (or 0.6% by weight or less, 0.5% by weight or less, 0.4% by weight or less). , 0.3% by weight or less, 0.2% by weight or less, or 0.1% by weight or less), and the 1,3-butylene glycol concentration as determined by gas chromatography analysis under the following conditions is 97.6 area% or more (or 97.8 area% or more, 98 area% or more, 98.2 area% or more, 98.4 area% or more, 98.6 area% or more, 98.8 area% or more, 99 area% or more, 99.1 area% or more, 99.2 area% or more, 99.3 area% or more, 99.4 area% or more, 99. 1,3-butylene glycol. 2,5-Dimethyl-2,5-diol. 3,5-Dimethyl-2,5-diol. 4,5-Dimethyl-2,5-diol. 5,5-Dimethyl-2,5-diol. 6,5-Dimethyl-2,5-diol. 7,5-Dimethyl-2,5-diol. 8,5-Dimethyl-2,5-diol. 9,5-Dimethyl-2,5-diol. 10,5-Dimethyl-2,5-diol. 11,5-Dimethyl-2,5-diol. 12,5-Dimethyl-2,5-diol. 13,5-Dimethyl-2,5-diol. 14,5-Dimethyl-2,5-diol. 15,5-Dimethyl-2,5-diol. 16,5-Dimethyl-2,5-diol. 17,5-Dimethyl-2,5-diol. 18,5-Dimethyl-2,5-diol. 19 ...9,5-Dimethyl-2,5-diol. 19,5-Dimethyl-2,5-di (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[27] The method for producing 1,3-butylene glycol according to

[26] , wherein the distillate rate in the product column is less than 30% by weight (or 29% by weight or less, 28% by weight or less, 27% by weight or less, 26% by weight or less, 25% by weight or less, 24% by weight or less, 23% by weight or less, 22% by weight or less, 21% by weight or less, 20% by weight or less, 19% by weight or less, 18% by weight or less, 17% by weight or less, 16% by weight or less, 15% by weight or less, 12% by weight or less, 10% by weight or less, 8% by weight or less, 5% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, 0.8% by weight or less, 0.6% by weight or less, or 0.4% by weight or less).

[28] The method for producing 1,3-butylene glycol according to

[26] or

[27] , wherein at least a portion of the distillate from the product column is recycled to a step preceding the product distillation step (for example, a dehydration step, a dealcoholization step, a low-boiling point removal step, or a step preceding these steps).

[29] The method for producing 1,3-butylene glycol according to

[28] , wherein the amount of the distillate from the product column recycled to a process prior to the product distillation process is 0.01% by weight or more (or 0.05% by weight or more, 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 1.5% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 7% by weight or more, 10% by weight or more, or 20% by weight or more) and less than 30% by weight, relative to the amount charged to the product column.

[30] The method for producing 1,3-butylene glycol according to any one of

[26] to

[29] , wherein the recovery rate of 1,3-butylene glycol in the product column is more than 80% (or 85% or more, 90% or more, 95% or more, or 99% or more).

[31] In the high boiling removal tower used in the high boiling removal step, the acetaldehyde content is 500 ppm or less (or 205 ppm or less, 200 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, less than 2 ppm, or less than 1 ppm), and the crotonaldehyde content is is 200 ppm or less (or 110 ppm or less, 100 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or less than 1 ppm), and the water content is 3% by weight or less (or 2% by weight or less, 1.2% by weight or less, 1.1% by weight or less, 1.0% by weight or less, 0.95% by weight or less). , 0.9% by weight or less, 0.8% by weight or less, 0.7% by weight or less, 0.6% by weight or less, 0.5% by weight or less, 0.4% by weight or less, 0.3% by weight or less, 0.2% by weight or less, or 0.1% by weight or less), and a 1,3-butylene glycol concentration of 95 area % or more (or 96 area % or more, 96.7 area % or more, 97 area % or more, 98 area % or more, or 99 area % or more) as determined by gas chromatography analysis under the above conditions. The method for producing 1,3-butylene glycol according to any one of the above

[26] to

[30] , wherein a feed solution containing butylene glycol is distilled under a reflux ratio of 0.03 or more (or 0.05 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, or 20 or more).

[32] The method for producing 1,3-butylene glycol according to any one of

[26] to

[31] , wherein the bottoms rate of the high boiling removal tower used in the high boiling removal step is less than 30% by weight (or 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, 7% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, or 1% by weight or less).

[33] The method for producing 1,3-butylene glycol according to any one of

[26] to

[32] , wherein the bottoms rate in the high boiling removal tower used in the high boiling removal step is 0.01% by weight or more (or 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 6% by weight or more, 7% by weight or more, 8% by weight or more, 9% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more).

[34] The method for producing 1,3-butylene glycol according to any one of

[26] to

[33] , wherein the recovery rate of 1,3-butylene glycol in the high boiling removal tower used in the high boiling removal step is more than 80% (or 85% or more, 90% or more, 95% or more, or 99% or more).

[35] The method for producing 1,3-butylene glycol according to any one of

[26] to

[34] , wherein at least a portion of the bottoms of the high boiling removal tower used in the high boiling removal step is recycled to a step preceding the high boiling removal step.

[36] The method for producing 1,3-butylene glycol according to

[35] , wherein the amount of the bottoms of the high boiling removal tower recycled to a step prior to the high boiling removal step is less than 30% by weight (or 25% by weight, 20% by weight or less, 15% by weight or less, 10% by weight or less, 7% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, or 1% by weight or less) of the amount charged to the high boiling removal tower.

[37] The method for producing 1,3-butylene glycol according to

[35] or

[36] , wherein the amount of the bottoms of the high boiling removal tower recycled to a step prior to the high boiling removal step is 0.01% by weight or more (or 0.1% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 7% by weight or more, 10% by weight or more, or 20% by weight or more) of the amount charged to the high boiling removal tower.

[38] A method for producing 1,3-butylene glycol, in which purified 1,3-butylene glycol is obtained from a reaction crude liquid containing 1,3-butylene glycol, The method includes a dehydration step for removing water by distillation and a high boiling point removal step for removing high boiling point components by distillation, In the high boiling removal tower used in the high boiling removal step, the acetaldehyde content is 500 ppm or less (or 205 ppm or less, 200 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, less than 2 ppm, or less than 1 ppm), the crotonaldehyde content is 200 ppm or less (or 110 ppm or less, 100 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or less than 1 ppm), and the water content is 3 wt. % or less (or 2% by weight or less, 1.2% by weight or less, 0.4% by weight or less, 0.3% by weight or less, 0.2% by weight or less, 0.1% by weight or less, 0.05% by weight or less, or 0.03% by weight or less), and a 1,3-butylene glycol concentration of 96.7 area % or more (or 97% or more, 98% or more, or 99% or more) as determined by gas chromatography analysis under the following conditions, is subjected to distillation under conditions of a reflux ratio of 0.03 or more (or 0.1 or more, 0.2 or more, 0.3 or more, 0.4% or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, or 20 or more). (Gas chromatographic analysis conditions) Analytical column: Column with a stationary phase of dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: Increase temperature from 80°C to 120°C at 5°C / min, then increase temperature to 160°C at 2°C / min and hold for 2 minutes. Further increase temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250℃ Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

[39] In the dehydration tower used in the dehydration step, the content of acetaldehyde is 1000 ppm or less (or 900 ppm or less, 800 ppm or less, 700 ppm or less, 600 ppm or less, 500 ppm or less, 400 ppm or less, 300 ppm or less, 200 ppm or less, 155 ppm or less, 140 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or 1 ppm or less), crotonaldehyde content 400 ppm or less (or 300 ppm or less, 200 ppm or less, 100 ppm or less, 150 ppm or less, 130 ppm or less, 117 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or 1 ppm or less), water a content of 1,3-butylene glycol of 90% by weight or less (or 85% by weight or less, 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 15% by weight or less, or 10% by weight or less), and a 1,3-butylene glycol concentration of 95% by area or more (or 96% by area or more, 96.7% by area or more, 97% by area or more, 98% by area or more, or 99% by area or more) as determined by gas chromatography analysis under the above conditions. The method for producing 1,3-butylene glycol according to any one of the above

[26] to

[38] , wherein the liquid is distilled under conditions of a reflux ratio of more than 0.3 (or 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, or 40 or more).

[40] The method for producing 1,3-butylene glycol according to any one of

[26] to

[39] , wherein the distillate rate in the dehydrating tower used in the dehydration step is 95% by weight or less (or 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, or 5% by weight or less).

[41] The method for producing 1,3-butylene glycol according to any one of

[26] to

[40] , wherein the recovery rate of 1,3-butylene glycol in the dehydration tower used in the dehydration step is 99.3% or more.

[42] The method for producing 1,3-butylene glycol according to any one of

[26] to

[41] , wherein the reaction crude liquid containing 1,3-butylene glycol is a reaction crude liquid obtained by hydrogen reduction of acetaldols.

[43] The method for producing 1,3-butylene glycol according to any one of

[26] to

[42] above, further comprising at least one step selected from an alkali treatment step of treating a process stream containing 1,3-butylene glycol with a base, a desalting step of removing salts in the process stream containing 1,3-butylene glycol, and a dealcoholization step of removing low-boiling substances including alcohol in the process stream containing 1,3-butylene glycol. [Industrial Applicability]

[0188] The 1,3-butylene glycol product according to the present disclosure is highly pure and colorless and odorless (or nearly colorless and odorless), and is resistant to coloration and odor development over time, and / or is resistant to an increase in acid concentration over time even when containing water. This 1,3-butylene glycol product has excellent moisturizing properties and can be used as a raw material for moisturizers and cosmetics that can maintain high quality for a long period of time. [Explanation of symbols]

[0189] A: Dehydration tower B: Desalination tower C: High boiling point removal distillation column (high boiling point removal column) D: Alkaline reactor E: Dealkalization tower F: Product distillation column (product column) A-1, B-1, C-1, E-1, F-1: Condenser A-2, C-2, F-2: Reboiler X-1: Crude 1,3-butylene glycol X-2: Water (drainage) X-3: Salt, high boiling point substances, and some 1,3-butylene glycol X-4: High boiling point substances and part of 1,3-butylene glycol X-5: Caustic soda, high boiling point substances, and some 1,3-butylene glycol X-6: Low boiling point substances and part of 1,3-butylene glycol Y: 1,3-butylene glycol products

Claims

1. A 1,3-butylene glycol product in which the content of at least one of eight contents, namely, the content of methyl vinyl ketone, the content of acetone, the content of butylaldehyde, the content of acetaldol, the content of a compound represented by the following formula (1), the content of a compound represented by the following formula (2), the content of a compound represented by the following formula (3), and the total content of a compound represented by the following formula (4) and a compound represented by the following formula (5), is less than 8 ppm. 【Chemical 1】

2. The 1,3-butylene glycol product according to claim 1, wherein the sum of the contents of methyl vinyl ketone, acetone, butyl aldehyde, acetaldol, the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (3), the compound represented by formula (4), and the compound represented by formula (5) is less than 71 ppm.

3. 3. The 1,3-butylene glycol product according to claim 1 or 2, wherein the acetaldol content is less than 8 ppm.

4. The 1,3-butylene glycol product according to any one of claims 1 to 3, wherein the content of at least the compound represented by formula (3) is less than 8 ppm.

5. The 1,3-butylene glycol product according to any one of claims 1 to 4, wherein the total content of methyl vinyl ketone, acetone, and butyraldehyde is 24 ppm or less.

6. The 1,3-butylene glycol product according to any one of claims 1 to 5, wherein the total content of the compound represented by formula (1), the compound represented by formula (2), the compound represented by formula (4), and the compound represented by formula (5) is 24 ppm or less.

7. 7. The 1,3-butylene glycol product according to any one of claims 1 to 6, having an acetaldehyde content of less than 4 ppm and a crotonaldehyde content of less than 2 ppm.

8. The 1,3-butylene glycol product according to any one of claims 1 to 7, having an acid concentration (as acetic acid) of less than 11 ppm, and having an acid concentration (as acetic acid) of less than 23 ppm after a 90 wt% aqueous solution is kept at 100°C for one week.

9. 9. The 1,3-butylene glycol product according to any one of claims 1 to 8, which has an APHA of 6 or less and an APHA of 78 or less after being kept in an air atmosphere at 180°C for 3 hours.

10. The 1,3-butylene glycol product according to any one of claims 1 to 9, which has an initial boiling point higher than 203°C and / or a dry point of 209°C or lower.

11. The 1,3-butylene glycol product according to any one of claims 1 to 10, which has a potassium permanganate test value of 30 minutes or more.

12. A moisturizer comprising the 1,3-butylene glycol product of any one of claims 1 to 11.

13. A cosmetic comprising the moisturizing agent according to claim 12.

14. A method for producing 1,3-butylene glycol, in which purified 1,3-butylene glycol is obtained from a reaction crude liquid containing 1,3-butylene glycol, comprising the steps of: The method includes a dehydration step for removing water by distillation, a high boiling point removal step for removing high boiling point components by distillation, and a product distillation step for obtaining purified 1,3-butylene glycol, In a product column used in the product distillation step, a 1,3-butylene glycol feed solution having an acetaldehyde content of 500 ppm or less, a crotonaldehyde content of 200 ppm or less, a water content of 0.7 wt% or less, and a 1,3-butylene glycol concentration of 97.6 area% or more as determined by gas chromatography analysis under the following conditions is subjected to distillation under conditions of a reflux ratio of 0.3 or more. (Gas Chromatography Analysis Conditions) Analytical column: a column whose stationary phase is dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: increase the temperature from 80°C to 120°C at 5°C / min, then increase the temperature to 160°C at 2°C / min and hold for 2 minutes, then increase the temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250°C Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

15. The method for producing 1,3-butylene glycol according to claim 14, wherein at least a portion of the distillate from the product column is recycled to a dehydration step, a dealcoholization step, a low-boiling point removal step, or a step preceding these steps, which are steps preceding the product distillation step.

16. A method for producing 1,3-butylene glycol, in which purified 1,3-butylene glycol is obtained from a reaction crude liquid containing 1,3-butylene glycol, comprising the steps of: The method includes a dehydration step for removing water by distillation and a high boiling point removal step for removing high boiling point components by distillation, In the high boiling removal tower used in the high boiling removal step, a feed solution containing 1,3-butylene glycol having an acetaldehyde content of 500 ppm or less, a crotonaldehyde content of 200 ppm or less, a water content of 3 wt% or less, and a 1,3-butylene glycol concentration of 96.7 area% or more as determined by gas chromatography analysis under the following conditions is subjected to distillation at a reflux ratio of 0.03 or more. (Gas Chromatography Analysis Conditions) Analytical column: a column whose stationary phase is dimethylpolysiloxane (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm) Temperature increase conditions: increase the temperature from 80°C to 120°C at 5°C / min, then increase the temperature to 160°C at 2°C / min and hold for 2 minutes, then increase the temperature to 230°C at 10°C / min and hold at 230°C for 18 minutes. Sample introduction temperature: 250°C Carrier gas: Helium Column gas flow rate: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280°C

17. The method for producing 1,3-butylene glycol according to any one of claims 14 to 16, wherein the reaction crude liquid containing 1,3-butylene glycol is a reaction crude liquid obtained by hydrogen reduction of acetaldols.

18. The method for producing 1,3-butylene glycol according to any one of claims 14 to 17, further comprising at least one step selected from the group consisting of an alkali treatment step of treating a process stream containing 1,3-butylene glycol with a base, a desalting step of removing salts in the process stream containing 1,3-butylene glycol, and a dealcoholization step of removing low boiling points including alcohol in the process stream containing 1,3-butylene glycol.

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