JP2023164367A - Method for producing colorful black lacquer - Google Patents

Abstract

To provide a method that can efficiently produce colorful black lacquer.SOLUTION: A method for producing colorful black lacquer includes a step for subjecting raw lacquer liquid to vacuum distillation, wherein a colorant is added to the raw lacquer liquid, or added to transparent black lacquer obtained after the vacuum distillation. Preferably, the vacuum distillation should be performed under these conditions: it should continue until the treated black lacquer has a moisture content of 3 wt.% or less; the pressure should be lowered by 25-60 hPa below the vapor pressure of the raw lacquer liquid; the process should last for at least 30 minutes; and it should be conducted at a temperature range of 20-35°C. The colorant preferably should be an inorganic pigment or an organic pigment, more preferably iron oxide, mercury sulfide, or a lake pigment.SELECTED DRAWING: None

Description

The present invention relates to a method for producing colorful Kurome lacquer.

Lacquer is a natural paint that has been used since ancient times. In general organic paints, a film is formed by a drying reaction of the paint film, whereas the film formation of lacquer involves its components, laccase and urushiol. That is, when lacquer is applied to a base material such as wood, laccase causes an oxidation reaction of urushiol using oxygen in the air, and further polymerizes urushiol in the presence of moisture to form a base material. A black film is formed on the material (Non-Patent Document 1). In this respect, lacquer can be said to be a so-called biological paint, different from general organic paints.
In the lacquer industry, colorful black-eyed lacquer is attracting attention both domestically and internationally. The current manufacturing process for colorful Kurome lacquer is carried out by adding and mixing pigments to transparent Kurome lacquer obtained by heating, stirring and refining raw lacquer. The production of colorful Kurome lacquer is said to be more difficult than the production of Transparent Kurome lacquer, as the viscosity increases rapidly when a large amount of pigment is added to Kurome lacquer, which has a low water content.

Kumanoya, T. (1991) Jasco Report, Vol. 33, No. 2, pp. 15-29.

When preparing transparent Kurome lacquer, the water content is adjusted. However, when pigments are mixed into Transparent Kurome lacquer as in the conventional method, the viscosity increases as mentioned above and the water content changes. It is very time consuming to uniformly mix the pigments and evaporate them until the water content is 3% by weight or less. Therefore, there is a problem in that the production cost of colorful Kurome lacquer is high. On the other hand, if pigments are added before heating and stirring the raw raw lacquer, the viscosity within the system will increase after the addition, and it is expected that it will take a long time to evaporate water by heating and stirring, making the work extremely difficult.

An object of the present invention is to provide a method that can efficiently produce colorful Kurome lacquer.

The present invention provides [1] to [9].
[1] A method for producing colorful Kurome lacquer, which includes a step of distilling raw raw lacquer containing raw lacquer under reduced pressure, and adding a coloring agent to the raw raw lacquer or to transparent Kurome lacquer obtained after vacuum distillation.
[2] The production method according to [1], wherein the vacuum distillation is performed until the water content after treatment becomes 3% by weight or less.
[3] The production method according to [1] or [2], wherein the vacuum distillation is performed by reducing the pressure by 25 to 60 hPa from the vapor pressure of the raw raw lacquer solution.
[4] The production method according to any one of [1] to [3], wherein the vacuum distillation is performed for 30 minutes or more.
[5] The production method according to any one of [1] to [4], wherein the vacuum distillation is carried out at 20 to 35°C.
[6] The manufacturing method according to any one of [1] to [5], wherein the colorant is an inorganic pigment or a synthetic pigment.
[7] The manufacturing method according to any one of [1] to [6], wherein the colorant is iron oxide, mercury sulfide, or lake pigment.
[8] Any one of [1] to [7], further comprising a soothing treatment step of stirring or grinding the raw raw lacquer liquid or raw lacquer under normal pressure at 35°C or lower, and/or a filtration treatment step. The manufacturing method described in.
[9] The coaxing process is carried out by at least one of the following methods: storing in a closed container and stirring the whole container, pulverizing using a mortar and pestle, and stirring and pulverizing using a crusher. The method described in [8].

The conventional method for producing colorful Kurome lacquer involves mixing pigments into clear Kurome lacquer obtained by refining raw lacquer, which has low production efficiency and makes it difficult to industrialize. On the other hand, according to the method of the present invention, a coloring agent can be mixed in advance with raw lacquer and the purification treatment can be performed by distillation under reduced pressure, so colorful black-eyed lacquer can be easily produced in a short time. Therefore, the present invention is expected to be a technology that can realize the mass production of colorful Kurome lacquer.

[Production method of colorful Kurome lacquer]
- Raw lacquer liquid -
The raw raw lacquer liquid contains raw lacquer and may further contain a coloring agent.

Raw lacquer is a substance that contains at least components derived from sumac sap, and is usually liquid. Raw lacquer may contain any of natural sap collected from sumac trees, synthetic products, and mixtures thereof.

The lacquer tree is a plant tree belonging to the Anacardiaceae family. The habitats of plants in the sumac family are generally Japan, Korea, China, and Southeast Asia, but the origin of the raw raw lacquer is not particularly limited. Examples of plants in the Anamondaceae family include plants containing urushiol as a main component (Toxicodendron vernicifera, production areas: China, Japan, Korea), plants containing lacquer as a main component (T. succedanea, production areas: Vietnam, Taiwan), and thithiol. There are three types of plants (Gluta usitata, produced in Myanmar, Cambodia, and Thailand) that contain it as a main ingredient.

The coloring agent may be any coloring agent other than the coloring components of lacquer, and may be either inorganic (for example, derived from minerals) or organic (for example, synthetic pigments or plant-extracted pigments). Examples of the inorganic colorant include inorganic pigments such as iron oxide (eg, Fe(OH) ₂ , Fe ₂ O ₃ ) and mercury sulfide (HgS). Examples of organic pigments include pigments containing dyes such as crocin and crocetin (for example, lake pigments).

Fe(OH) ₂ as iron oxide is preferably highly purified (substantially free of impurities). Examples of impurities include water-insoluble components (eg, water-insoluble iron oxide compounds). Such Fe(OH) ₂ can be obtained, for example, by the following method. Preferably, it is prepared by reacting iron sulfate (FeSO ₄ ) with sodium hydroxide (NaOH). For example, there is a method in which a sodium hydroxide aqueous solution is mixed with an aqueous iron sulfate solution to generate a black-green precipitate of iron sulfate, which is washed with water if necessary to remove the sodium sulfate (Na ₂ SO ₄ ) that is produced at the same time. Can be mentioned. Removal of sodium sulfate can be confirmed by addition of barium chloride (BaCl ₂ ) and no precipitation as barium sulfate (BaSO ₄ ). The iron oxide after the reaction (after washing and/or confirmation of removal of sodium sulfate) is further subjected to dehydration treatment (for example, by contacting with filter paper or centrifuging) to recover Fe(OH) ₂ precipitate. This makes it possible to reduce the amount of water, thereby making it possible to suppress aggregation reactions and improve the efficiency of vacuum distillation (shortening the time, etc.).

In this specification, Kurome lacquer prepared from additive-free raw raw lacquer is sometimes referred to as transparent Kurome lacquer, and may be distinguished from colorful Kurome lacquer containing colorants. The coloring agent may be included in the raw raw lacquer solution, or may be added to the transparent black-eye lacquer obtained after the vacuum distillation process of the raw raw lacquer liquor and the optional soothing process. Colorful Kurome lacquer has various hues depending on the type of colorant used. Depending on its hue and the type of coloring agent, it is sometimes called, for example, Bengara Kurome lacquer, Roiro Kurome lacquer, vermilion Kurome lacquer, Roki Kurome lacquer, Nashiji Kurome lacquer, or Botan Kurome lacquer.

The content of coloring agent in the raw raw lacquer solution varies depending on the type of colorant, and it is difficult to generalize, but to give an example, it is usually 5% by weight for 100% by weight of the lacquer to be added (raw lacquer or transparent black lacquer). % or more, preferably 6% by weight or more, more preferably 7% by weight or more. The upper limit is usually 150% by weight or less, 140% by weight or less, 130% by weight or less, 100% by weight or less, 70% by weight or less, 65% by weight or less, or 60% by weight or less. In the case of raw lacquer, the content is usually 5% by weight or more, preferably 6% by weight or more, and more preferably 7% by weight or more, based on 100% by weight of raw lacquer. The upper limit is 70% by weight or less, preferably 65% by weight or less, more preferably 60% by weight or less.

-Vacuum distillation-
By performing vacuum distillation treatment, it is possible to safely obtain high-quality colorful black-eye lacquer in a shorter time than with conventional methods, while suppressing the onset of rashes.

The conditions for vacuum distillation are not particularly limited, but an example is as follows. The pressure is preferably reduced by 25 hPa or more, more preferably 30 hPa or more, from the vapor pressure. The reduced pressure condition is preferably 25 to 60 hPa lower than the vapor pressure, more preferably 30 to 50 hPa lower than the vapor pressure. This makes it possible to sufficiently remove low-boiling point volatile terpenes, gas components, and moisture contained in the raw raw lacquer in a short time.

The temperature of vacuum distillation is usually below room temperature (eg, below 38°C, below 35°C, or below 30°C), preferably between 20 and 35°C, more preferably between 20 and 30°C. Thereby, deactivation due to denaturation of laccase contained in the raw raw lacquer can be suppressed.

The time for vacuum distillation is preferably 30 minutes or more, more preferably 40 minutes or more. The upper limit is not particularly limited, but is usually 200 minutes or less, 180 minutes or less, 120 minutes or less, preferably 80 minutes or less. This makes it possible to obtain colorful black-eyed lacquer with an appropriate moisture content.

The moisture content during vacuum distillation is measured and managed, and the desired moisture content (for example, 3.5% by weight or less, 3.2% by weight or less, or 3% by weight or less, preferably 2.5% by weight or less, or 2% by weight) (below), the vacuum distillation may be terminated and the product may be recovered. Methods for measuring moisture content include, for example, the loss on drying method, near-infrared spectroscopy, gas chromatography, and Karl Fischer method, and among these methods, accurate quantification is possible even with a small sample, and the sensitivity is good. The Karl Fischer method is preferred because of its excellent reproducibility. The Karl Fischer method utilizes the fact that the Karl Fischer reagent (an electrolyte containing iodide ions, sulfur dioxide, and alcohol as its main components) specifically reacts with water in the presence of methanol in a titration cell. This is a method to quantify the moisture content. The Karl Fischer method is classified into a volumetric titration method and a coulometric titration method depending on the titration procedure, with the volumetric titration method being preferred. In the volumetric titration method, a titration flask is filled with a dehydrated solvent suitable for the sample (e.g., anhydrous molecular sieves), the titration agent is used to make it anhydrous, the sample is added, and the titer (mgH ₂ O/mL) is standardized in advance. Titration is performed using the titrant that has been prepared in advance, and the water content in the sample is accurately determined as weight % from the titration (mL).

- Nayashi treatment (example of pre-treatment of raw lacquer) -
The raw lacquer solution or the raw lacquer before addition of the colorant may be subjected to pretreatment (calming treatment). By performing the soothing treatment, the micelle particles of different sizes (aqueous phase) containing water and water-soluble proteins that exist in raw lacquer are destroyed, and the micelles are uniformly dispersed in the oil phase containing urushiol. This can promote water recovery during vacuum distillation. Moreover, the gloss and/or viscosity of the obtained colorful black-eye lacquer can be increased.

Examples of methods for soothing treatment include stirring and pulverizing the raw raw lacquer; storing it in an airtight container and stirring the whole container (e.g., rotary stirring); or pulverizing it using a mortar and pestle. or a method of crushing using a grinder is preferred. In the case of a method using a closed container, the container provided in the apparatus used for vacuum distillation may be used as is. Temperature conditions for the tempering treatment are preferably lower than that of vacuum distillation, usually preferably 35°C or lower, more preferably 34°C or lower, or 33°C or lower, 32°C or lower, 31°C or lower, or 30°C. The following are more preferable. The lower limit is usually 20°C or higher, preferably 22°C or higher, or 23°C or higher, more preferably 24°C or higher, or 25°C or higher. The pressure is usually normal pressure (atmospheric pressure, usually 1 atm), and it is preferable that pressure reduction and pressure treatment are not performed. The treatment time is usually 15 minutes or more, preferably 20 minutes or more. The upper limit is 250 minutes or less, 200 minutes or less, 180 minutes or less, 100 minutes or less, preferably 90 minutes or less, more preferably 80 minutes or less.

The processing time for the processing using a mortar and pestle or the processing using a crusher is usually 10 minutes or more, preferably 15 minutes or more. There is no particular upper limit, but it is usually 60 minutes or less, 50 minutes or less, preferably 40 minutes or less.

As a crusher, an agitator crusher having a bowl and a plurality of rods (pestles) that rotate around and around the inside of the bowl and can press the contents of the bowl (for example, Japanese Patent Application Laid-Open No. 110756/1983, Ishikawa type stirring crusher) A crusher (manufactured by Ishikawa Factory Co., Ltd.) is preferred. Thereby, stirring and/or grinding (for example, grinding) can be carried out efficiently. When using a stirrer and crusher, the rotation speed is preferably 20 rpm or more, more preferably 25 rpm or more. The upper limit is preferably 30 rpm or less.

Nail treatment is either a process using a mortar and pestle or a process using a crusher; or a combination of a process using a closed container and a process using a mortar and pestle or a process using a crusher. is preferred.

The temperature condition for the soothing step is preferably 35° C. or lower. This allows water to be removed to about 3% or less in a short period of time (usually within 2 hours) at low temperatures, thereby avoiding laccase denaturation.

-Filtration (example of pre-treatment of raw lacquer)-
The raw lacquer solution or the raw lacquer before adding a colorant may be subjected to a filtration treatment. Filtration treatment can remove insoluble components contained in raw lacquer.

The filtration treatment may be performed at least once, or may be performed two or more times. The filtration can be performed before or after the depressurization treatment, and in the case of performing the decompression treatment, it is preferably performed before the decompression treatment. By the filtration treatment, impurities that may be contained in the raw raw lacquer can be removed, and in the case where a soothing treatment is performed, insoluble components such as insoluble melanin pigments that may be generated at that time can also be removed. Since these components that may cause light scattering can be removed, the gloss and/or luster of the resulting colorful Kurome lacquer can be further enhanced. Furthermore, by adjusting the conditions such as the time and type of soothing treatment, the gloss and/or luster of the resulting colorful Kurome lacquer can be adjusted as desired. In this specification, raw lacquer that has been filtered prior to vacuum distillation is referred to as lacquer-flavored raw lacquer, and may be distinguished from coarse-flavored raw lacquer, which is unfiltered raw lacquer.

The filter medium used for filtration is not particularly limited, and examples thereof include cloth such as cotton and gauze, paper such as filter paper (for example, Japanese paper, regenerated cellulose paper, and test filter paper), and metal such as wire mesh. The filter medium may be a combination of two or more filter mediums. Among these, cotton, filter paper, or a combination thereof is preferred. Cotton and filter paper are filter media that have traditionally been used in the production of lacquer-flavored raw lacquer, and are preferably used. The filtration method may be carried out under conditions suitable for the filter medium. When cotton is used, for example, a method of soaking an appropriate amount of cotton (for example, an amount corresponding to 5 to 20% by weight of the weight of the lacquer) in lacquer and leaving it to stand (for example, 10 to 20 minutes) can be mentioned. When using filter paper, for example, lacquer is poured onto the top surface of the filter paper, and the filtrate that seeps out from the bottom surface is squeezed and collected. When using a combination of cotton and filter paper, the order of filtration through cotton and filtration through filter paper is not particularly limited, but it is preferable to perform the former first. Thereby, the sample in which the cotton is soaked can be poured onto the filter paper, and the treated lacquer can be recovered as a liquid that has passed through the filter paper (the filter paper may be squeezed if necessary).

It is preferable that the raw lacquer has undergone either a filtration treatment or a soothing treatment, and more preferably both.

By the method of the present invention, colorful Kurome lacquer can be stably obtained in a short time. Colorful Kurome lacquer exhibits color development depending on the colorant used, and can exhibit good gloss, luster, and/or viscosity.

Example 1 (Sample 1: Bengara Kurome lacquer)
[Soothing treatment]
The amounts of Shiroguchi lacquer raw lacquer (manufactured by Tsujita Urushiten, refined on January 27, 2022, the same applies hereinafter) and Bengara pigment (Bura) shown in Table 1 were placed in a glass mortar (200ml, Sigma-Aldrich). After adding the mixture, grind it strongly with a glass pestle for 20 to 30 minutes at room temperature. ) and a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a water bath, the system was replaced with argon, and stirred at 35°C for 20 to 40 minutes at normal pressure. A palm-treated sample was obtained.

[Vacuum distillation]
The parched sample was maintained in the flask, the system was replaced with argon, the vapor pressure was reduced by approximately 40 hPa, and vacuum distillation was performed at 35°C until no bubbles were generated (distillation time: 70 minutes). ), Sample 1 (Begara Kurome lacquer) was collected (Table 1).

Using a Karl Fischer moisture meter (manufactured by Metrohm), the moisture content of each sample was measured before and after the vacuum distillation was started (n=3).
The measurement conditions were as follows.
Sample weight at the start of vacuum distillation: 50mg±5mg
Temperature: 180℃
Extraction time: 400 seconds Flow rate: 80 ml/min At the end of the reaction, the air flow was stopped, and after measuring the moisture content, the sample was taken out from the moisture meter.
Flow rate: 80ml/min

Example 2 (Sample 2: Roiro Kurome lacquer)
The same procedure as in Example 1 was carried out except that FeSO ₄ and NaOH in the amounts shown in Table 1 were used instead of the Bengara pigment, to obtain dark black Roiro Kurome lacquer (Sample 2).

Example 3 (Sample 3: Vermilion black lacquer)
In place of the Bengara pigment, the procedure was repeated in the same manner as in Example 1, except that Nikka shu (HgS, Yamamoto Scinnabar) was used in the amount shown in Table 1, to obtain vermilion Kurome lacquer (sample 3).

Example 4 (Sample 4: Pink black lacquer)
The same procedure as in Example 1 was carried out, except that instead of Bengara pigment, Botan pigment (Lake pigment, Permanent Color Kurobako Botan, Tsutsumi Asakichi Lacquer Store) was used in the amount shown in Table 1.

Reference examples 1 to 2 (Samples 5 to 6: Clear black lacquer)
The same procedure as in Example 1 was carried out except that no pigment was added.

Comparative Example 1 (Sample 7: Commercially available transparent black-eye lacquer)
The same procedure as in Example 1 was carried out except that no pigment was added.
Sample 7 was transparent Kurome lacquer (Tsujita Shoten).

(Glossiness)
The glossiness of Samples 1 to 7 was measured using the following procedure. A wooden board was prime coated with Shiroguchi Arami Nama Urushi and dried at 25°C and 75% humidity for 12 hours. Subsequently, an intermediate coating was applied with Shiroguchi rough raw lacquer and abrasive powder (rust) (raw lacquer: abrasive powder = 8:2 mixture) and dried at 25° C. and 75% humidity for 12 hours. Next, it was overcoated with Shiroguchiro Irokurome lacquer (Tsujita Urushiten, refined in September 2021) and dried at 25°C and 75% humidity for 12 hours. After that, the surface was polished with sandpaper. After coating and polishing, divide the wooden plate into sections with tape (approximately 5 cm x approximately 10 cm per section), drop one drop of Samples 1 to 7 into each section, coat uniformly, and heat at 25°C. It was dried for 12 hours at a humidity of 75%. Thereafter, the glossiness (measurement angle 60°, bulb 90) was measured three times using a handy glossmeter Gloss Checker IG-331 (manufactured by HORIBA), and the average value was taken as the glossiness (Table 1). Note that the control conditions were set to 90 at a measurement angle of 60°.

(viscosity)
One drop of each sample was placed on a glass plate and left at room temperature for 30 minutes. The distance from the spot to the end of the stream was measured to determine the viscosity (numbers are shown in Table 1 in descending order of viscosity).

Samples 1 to 4, which were colorful black-eyed lacquer, tended to have higher gloss than samples 5 and 6, which were transparent black-eyed lacquer. The viscosities of Samples 1 to 4 were higher than that of Sample 7, a commercially available product, and all were within the acceptable range (Table 1).

In Example 1, the same results as in Example 1 were also obtained when the pressure after reduced pressure in vacuum distillation was changed to about 25 hPa and the distillation time was adjusted to about 70 to 90 minutes.

Example 5 (Preparation of Roirokurome lacquer using purified Fe(OH) ₂ )
[Purification of _FeSO4 ]
500 ml of distilled water was added to 162 mmol (45 g) of FeSO ₄ (Sigma-Aldrich, Catalog No. 7782-63-0) and stirred. The resulting FeSO ₄ suspension was filtered using filter paper (ADVANTEC® filter paper 2) to remove iron oxide (not dissolved) and the liquid phase was separated. This liquid phase was put into a vacuum flask of a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a Diaphragm vacuum pump (NVP-2100, Tokyo Rikakikai Co., Ltd.) and a water bath, and the system was replaced with argon. The mixture was stirred at 35°C for 2 hours. The 42 g of green crystals recovered were purified _FeSO4 .

[Preparation of Fe(OH) ₂ ]
4.2 mmol (1.16 g) of purified FeSO ₄ obtained by the above procedure was dissolved in 100 ml of distilled water to prepare a FeSO ₄ solution. On the other hand, 8.4 mmol (0.336 g) of NaOH was dissolved in 100 ml of distilled water to prepare a NaOH solution, and this was added to the FeSO ₄ solution while stirring well to generate a uniform precipitate (black green color). It was left for 1 hour. After standing, a FeSO ₄ solution was added so that the pH of the supernatant was neutral to weakly acidic (approximately 5 to 6.5). After standing for another hour, the supernatant was removed, and the residue was washed with distilled water at least 5 times to remove the byproduct Na ₂ SO ₄ . The residue after washing was converted to Fe(OH) in the following step. It was used as ₂ . The removal of Na ₂ SO ₄ from the sample by washing was confirmed by the fact that no white precipitate (BaSO ₄ ) was generated when 0.1 M BaCl ₂ aqueous solution was mixed with the washing solution at a ratio of 1:1. The residue after washing was dehydrated by centrifugation at room temperature and 200 rpm.

[Preparation of Roirokurome lacquer]
1 g of Fe(OH) ₂ obtained by the above procedure was added to 50 g of the same lacquer-flavored raw lacquer as in Example 1 (2% by weight of Fe(OH) ₂ based on the lacquer-flavored raw lacquer). The same pulverization treatment as in Example 1 was carried out, except that the pulverization time was 15 minutes, and then the same vacuum distillation and water removal as in Example 1 were carried out, except that the treatment time was 2.5 hours. After confirmation, we obtained Roirokurome lacquer. The moisture content before vacuum distillation was 27.74%, the moisture content after vacuum distillation was 2.15%, and the gloss was 115, indicating that the gloss was significantly improved compared to Example 1. .

Examples 6-9 (Preparation of white lacquer)
The amount of Shiroguchi lacquer raw lacquer shown in Table 2 (manufactured by Tsujita Urushiten, refined on January 27, 2022, the same applies hereinafter) was added to an Ishikawa-type stirring and crushing machine (manufactured by Ishikawa Factory Co., Ltd., vertical type (pulley type) No. 22). External dimensions of the machine: length 610mm, width 610mm, height 1450mm; Equipped with a porcelain pot (inner diameter 305mm, depth 170mm, usable volume 4.0L), T-shaped porcelain pestle (2 pieces), and scraping board (wooden) ; Electric motor (motor single phase 100V 0.2kW); Pestle rotates in the same direction at a rate of about 2.4 revolutions per revolution) (The bowl can be pulled forward and tilted forward when pulled out. The mixture was poured into a pot (modified so that the contents of the pot could be easily taken out) and treated at room temperature with a pestle at 26 rpm for 15 minutes. In order to confirm that the vacuum in the evaporator was operating normally before starting vacuum distillation, an empty flask was attached to the evaporator and then vacuum treatment was performed at 25 hPa for 15 minutes. After confirming that the depressurization process has been successfully achieved, take out the crushed sample by pulling the crusher bowl forward and tilting it forward, placing it in a flask, attaching it to the evaporator, and lowering the temperature of the water bath. The temperature was adjusted to about 15° C., and the pressure was reduced to 25 hpa for 15 minutes to remove low-boiling substances such as terpenes. After 15 minutes (after reaching 25 hpa), water was removed by distillation under reduced pressure while gradually heating the water bath temperature to 35°C. It was estimated that the distillation was almost completed in 2 hours, but the temperature of the water bath was further adjusted to 38° C. and distillation was carried out under reduced pressure for 30 minutes (total evaporator treatment time; 2.5 to 3 hours). After confirming that the moisture content of the sample after processing is 3% or less by quantification using a Karl Fischer moisture meter (injecting the sample into a vial and quantifying it at 180 ° C. for 400 seconds and at a wind speed of 100 mL/min), The vacuum distillation was stopped and the purified Kurome lacquer was collected. Thereafter, it was filtered through a filter paper (made by Rayon, trade name: Miyoshino Paper (530 mm x 300 mm), manufactured by Otsuka Brush Manufacturing Co., Ltd.) to obtain transparent black-eye lacquer.

A white pigment (manufacturer name: Tsutsumi Asayoshi Urushiten, product name: Permanent Color) was added and mixed in the ratio shown in Table 2 to the obtained transparent black-eye lacquer to prepare white lacquer.

The obtained white lacquer had good gloss.

Example 10 (Production of Bengara Kurome Urushi 10)
The amounts of raw lacquer and Bengara pigment were adjusted to the amounts shown in Table 3, and the same pulverization treatment as in Example 6 was performed (however, the pulverization time was 30 minutes). Thereafter, the same vacuum distillation treatment as in Example 5 was performed except that the vacuum distillation time was changed to 3 hours (Table 3).

Example 11 (Production of Bengara Kurome lacquer)
Example 10 except that transparent black-eye lacquer (manufactured by Iwate Urushi Tech Co., Ltd.) was used instead of raw lacquer, the amounts of each raw material used were as shown in Table 3, and the distillation time was 2.5 hours. It was carried out in the same manner as (Table 3).

The obtained Bengara Kurome lacquer showed good gloss.

Examples 12 to 19 (manufacture of colorful lacquer)
Example 6 was carried out in the same manner as in Example 6, except that the amounts of pigment and transparent black-eye lacquer were changed to the types and amounts shown in Table 4 (Table 4). As a result, all colorful lacquers had low water content, exhibited good gloss, and had a high recovery rate.

Claims (9)

A method for producing colorful Kurome lacquer, which includes a step of distilling raw raw lacquer containing raw lacquer under reduced pressure, and adding a coloring agent to the raw raw lacquer or to transparent Kurome lacquer obtained after vacuum distillation. The manufacturing method according to claim 1, wherein the vacuum distillation is performed until the water content after treatment becomes 3% by weight or less. The production method according to claim 1 or 2, wherein the vacuum distillation is performed at a pressure of 25 to 60 hPa lower than the vapor pressure of the raw raw lacquer solution. The manufacturing method according to claim 1 or 2, wherein the vacuum distillation is performed for 30 minutes or more. The production method according to claim 1 or 2, wherein the vacuum distillation is carried out at 20 to 35°C. The manufacturing method according to claim 1 or 2, wherein the colorant is an inorganic pigment or an organic pigment. The manufacturing method according to claim 1 or 2, wherein the coloring agent is iron oxide, mercury sulfide, or lake pigment. The manufacturing method according to claim 1 or 2, further comprising a soothing treatment step of stirring or pulverizing the raw raw lacquer liquid or raw lacquer under normal pressure at 35° C. or lower, and/or a filtration treatment step. Claim 8, wherein the coaxing step is carried out by at least one of the following methods: storing in a closed container and stirring the whole container, pulverizing using a mortar and pestle, and stirring and pulverizing using a crusher. The method described in.