Process for the production of liquid soaps

Abstract

To provide a method for producing a liquid soap, by which the liquid soap can simply be produced in a short time at a low cost without heating.SOLUTION: The method for producing a liquid soap of the present invention includes a step (1) of adding an ethyl alcohol (B) and a water (C) base (D) to an oil (A), a step (2) of stirring the mixture in the step (1) to cause a saponification reaction, a step (3) of diluting the mixture after the saponification reaction by adding either or both of an ethyl alcohol (B1) and water (C1), a step (4) of adding an acid (E) to neutralize the mixture, and a step (5) of allowing the mixture to stand and defoam. The oil (A) may be a waste oil and the ethyl alcohol (B) may be a denatured alcohol or an alcohol preparation having <60 wt.% ethyl alcohol content.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing liquid soap, and more particularly to a method for easily producing liquid soap without heating, in a short time, at low cost. [Background technology]

[0002] Vegetable oil used for frying in ordinary households is usually solidified with absorbent paper or the like and incinerated as waste oil. In the food industry, for example, in restaurants and hotels, vegetable oil is used in large quantities for frying and is then disposed of as waste oil.

[0003] The main component of such waste oil is triglyceride, a compound of plant-derived fatty acids and glycerin. In waste oil, some of the triglycerides are hydrolyzed by the water contained in fried vegetables, etc., resulting in the release of free fatty acids as a secondary component. These free fatty acids contribute to saponification. It is also known that waste oil can be used as biofuel for diesel or jet engines.

[0004] While waste oil is a global resource and has become a marketable product, in Japan this trend has been slow, and most of the waste oil generated in households is incinerated. In recent years, soap production using waste oil at home has been proposed as an effective way to utilize this waste oil.

[0005] Non-Patent Document 1 states that soap has an affinity with the skin, is highly biodegradable even when released into the natural environment such as rivers, is not ecotoxic to aquatic organisms, and does not contain nitrogen or phosphorus that pollute marine areas. It also states that although the use of soap has decreased significantly in recent years due to the widespread use of synthetic detergents, soap still accounts for about 40% of body washes, and is particularly popular in Japan, a country with soft water.

[0006] For example, Non-Patent Document 2 introduces a method for easily making handmade soaps in the kitchen, such as olive soap. This method requires heating to initiate the saponification reaction required for soap formation.

[0007] Also, Non-Patent Document 3 describes how to make handmade CP (cold process) soap. Non-Patent Document 4 explains how to make soap using the cold process method, and states that it takes about 45 days to complete because it needs to be aged for about 40 days.

[0008] Such conventional methods entailed dangers, such as the need to first dissolve in water the strong alkaline components caustic soda and caustic potash, which required careful handling, before use. They also required several different containers, including one for measuring the raw materials, one for the saponification reaction (such as the simplest milk carton), and one for liquefying the solidified material.

[0009] In addition, conventional methods have the problem of high raw material costs due to the use of purified water and high-concentration ethyl alcohol as a saponification accelerator, and require a significant amount of time, taking at least one or two days, or more than one month if a cold process method is used. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] "Soap Science Recommendations: Innocence Given by an Angel (Hobby)" by Kland, ASIN: B08RF1J551, released on January 1, 2021 [Non-patent document 2] Kyoko Maeda, "Making Olive Soap and Marseille Soap - The Pleasure of Bathing" Textbook, Asuka Shinsha, released March 28, 2001 [Non-patent document 3] "Handmade soap that moisturizes the mind and body and is gentle on the skin" by Kazumi Kinoshita, published by Oizumi Shoten, on sale March 31, 2021 [Non-patent document 4] COCOON, "How to Make Soap ~Cold Process Method~", [online], posted on January 12, 2021, [Retrieved April 19, 2024], Internet<URL:https: / / cocoon-soap.com / readpost / 00039 / > Summary of the Invention [Problem to be solved by the invention]

[0011] As mentioned above, most conventional soap manufacturing methods require heating to accelerate the saponification reaction. Furthermore, these methods require a significant amount of time to produce soap. Furthermore, the process is complicated, requiring multiple containers, and expensive raw materials, making it difficult to produce soap at home.

[0012] Therefore, an object of the present invention is to provide a method for easily producing liquid soap without heating, in a short time, at low cost. [Means for solving the problem]

[0013] In order to solve the above problems, the present inventors discovered that by blending ethyl alcohol and potassium hydroxide with oil, the saponification reaction can be accelerated even without heating, making it possible to produce liquid soap in a short time without the need for aging, etc. They also discovered that liquid soap can be produced using inexpensive alcohol preparations in addition to ethyl alcohol. Furthermore, they discovered that liquid soap can be produced in a single container, making it easy to produce liquid soap at home, and thus completed the present invention.

[0014] The present invention provides a method for producing liquid soap, which comprises step (1) of adding ethyl alcohol (B), water (C) and a base (D) to oil (A), step (2) of stirring the mixture of step (1) to cause a saponification reaction, step (3) of diluting the mixture after the saponification reaction by adding either or both of ethyl alcohol (B1) or water (C1), step (4) of neutralizing by adding an acid (E), and step (5) of defoaming.

[0015] The present invention also provides the above-mentioned method for producing liquid soap, wherein the oil (A) is waste oil.

[0016] The present invention also provides the above-mentioned method for producing liquid soap, wherein the ethyl alcohol (B) is a denatured alcohol or an alcohol preparation having an ethyl alcohol content of less than 60% by weight.

[0017] The present invention also provides a method for producing a liquid soap, wherein in the above-mentioned production method, the saponification reaction is carried out without heating in step (2).

[0018] The present invention also provides the above-mentioned method for producing liquid soap, wherein the base (D) is potassium hydroxide and the acid (E) is citric acid.

[0019] The present invention also provides a kit for producing liquid soap, comprising ethyl alcohol (B), a base (D), and an acid (E).

[0020] The present invention also provides a kit for producing liquid soap, wherein the ethyl alcohol (B) is denatured alcohol or an alcohol preparation having an ethyl alcohol content of less than 60% by weight, and the base (D) is potassium hydroxide. [Effects of the Invention]

[0021] By using the present invention, liquid soap can be produced in a short time even without heating. Furthermore, the present invention allows the use of inexpensive raw materials, making it possible to produce liquid soap at low cost. Furthermore, since it can be produced in a single container, liquid soap can be easily produced at home. [Brief explanation of the drawings]

[0022] [Figure 1] Graph showing the evaluation results of a liquid soap according to one embodiment of the present invention. [Figure 2] FIG. 1 shows a questionnaire used to evaluate the quality of the liquid soap of an embodiment of the present invention. [Figure 3] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] The method for producing liquid soap of the present invention includes the following steps (1) to (5).

[0024] [Process (1)] Step (1) is a step of adding ethyl alcohol (B), water (C), and a base (D) to oil (A). Ethyl alcohol (B), water (C), and base (D) are not particularly limited, but for example, they can each be added separately to oil (A). The order of addition of ethyl alcohol (B) and water (C) does not matter. The base (D) can be added after the addition of ethyl alcohol (B) and water (C). The method of addition is not particularly limited, but for example, oil (A), ethyl alcohol (B), water (C), and base (D) can be added in this order to a container to be stirred in step (2), or oil (A), water (C), ethyl alcohol (B), and base (D).

[0025] The amount of ethyl alcohol (B) added in step (1) is not particularly limited, but for example, if the liquid soap to be produced is taken as 100% by weight, it may be 5 to 25% by weight as 100% ethyl alcohol, and preferably 7.5 to 15% by weight.

[0026] The amount of water (C) added in step (1) can be adjusted so that the concentration of the base (D) dissolved in the water contained in the mixture (aqueous solution concentration) becomes a concentration (25 to 35%) that can make the saponification reaction extremely fast. The aqueous solution concentration of the base (D) can be calculated using the following formula. (weight of base / (weight of base + weight of water in the mixture)) x 100 When an alcohol preparation containing water is used as ethyl alcohol (B), "water contained in the mixture" refers to the combination of water contained in the preparation used as ethyl alcohol (B) and water (C) added separately. In step (1), water (C) is added separately from the water contained in the preparation used as ethyl alcohol (B) to adjust the concentration of the base (D) dissolved in the water contained in the mixture.

[0027] The amount of base (D) added in step (1) is preferably an amount such that the concentration of the aqueous solution of base (D) in the water contained in the mixture obtained in step (1) is 25 to 35%, in order to accelerate the saponification reaction.

[0028] [Process (2)] Step (2) is a step of stirring the mixture of step (1) to cause a saponification reaction.

[0029] In step (2), saponification can be completed by contacting oil such as waste oil with a highly concentrated aqueous solution of base in the presence of a certain amount of ethyl alcohol. The time required for the saponification reaction in step (2) can be the time required for the saponification reaction to be completed, and can be, for example, 30 minutes or more, or 1 hour or more. The time required for the saponification reaction in step (2) can be approximately 1 hour, for example, 30 minutes to 3 hours, depending on the stirring means. The saponification reaction can be shortened by allowing it to proceed while mixing with a mixer. For example, using a whisk-type stirring blade shaped like a whisk allows the reaction to proceed efficiently, and the saponification reaction can proceed sufficiently even in about 1 hour.

[0030] The saponification reaction is a reaction in which glycerin esters (triglycerides) of medium-chain to higher fatty acids contained in fats and oils are reacted with a base to hydrolyze them into salts of fatty acids (soap) and polyhydric alcohols (glycerin).

[0031] Any mixer can be used to mix the mixture. Because the viscosity of the mixture increases dramatically during the saponification process, mixers such as stand mixers that combine mixing and kneading functions are more suitable than mixers that use rotating blades. There are many models of stand mixers, from industrial to home use. Mechanically, mixers that mix using a double spiral are preferred, and for home use, a tabletop stand mixer with a capacity of approximately 5 to 10 L is suitable. In the examples described below, an 8 L mixer was used. Note that saponification requires high-speed mixing, so hand mixers are not suitable.

[0032] From an eco-friendly perspective, step (2) is preferably carried out without heating. In the present invention, the incorporation of ethyl alcohol promotes the saponification reaction even without heating, allowing liquid soap to be produced in a short time. However, when handling oils and fats that have a freezing point near room temperature and can become solid depending on the temperature, heating may be performed to liquefy them.

[0033] In this specification, "under no heating" means that no intentional heating is performed, and includes not only the case where the mixture being stirred is at room temperature, but also the case where the temperature of the mixture naturally rises due to heat generated by a chemical reaction, etc. In this specification, "room temperature" means 15 to 30°C.

[0034] [Process (3)] The method for producing liquid soap of the present invention employs a step (3) after step (2) and before step (4), in which the mixture after the saponification reaction is diluted by adding either ethyl alcohol (B1) or water (C1), or both. In step (3), the high-concentration liquid soap obtained by the saponification reaction can be stabilized by diluting it with either ethyl alcohol (B1) or water (C1), or both. When both ethyl alcohol (B1) and water (C1) are added, ethyl alcohol (B1) can be added first. The addition of ethyl alcohol helps to liquefy the paste state of the high-concentration potash soap after saponification. On the other hand, adding water (C1) first may excessively promote gelation of the system during the process, potentially hindering the rapid production of liquid soap. It is preferable to add water (C1) all at once after adding ethyl alcohol (B1). If water (C1) is added gradually, the system that has been liquefied by the addition of ethyl alcohol (B1) may suddenly gel, which may hinder the dilution effect of adding water (C1). It is preferable to add ethyl alcohol (B1) and water (C1) separately, rather than mixing them in advance. If they are mixed in advance and then added, the system that has become a paste after saponification may suddenly gel. The ethyl alcohol (B1) and water (C1) may be the same as the ethyl alcohol (B) and water (C) used in step (1), respectively, or different ones may be used.

[0035] When ethyl alcohol (B1) is added in step (3), the amount of ethyl alcohol (B1) added is not particularly limited, but may be 1 to 10% by weight, and preferably 2 to 5% by weight, as 100% ethyl alcohol, assuming that the liquid soap to be produced is 100% by weight.

[0036] [Process (4)] Step (4) is a step of adding an acid (E) to neutralize the excess base. In step (4), the acid is added to the diluted mixture obtained in step (3). The method for adding the acid is not particularly limited, and known methods can be used.

[0037] Although there is no particular limitation, the acid is added so as to adjust the pH to a predetermined value. The pH adjusted by adding the acid is preferably a weak alkali of about 9.5 to 11.0.

[0038] [Process (5)] Step (5) is a step of defoaming the neutralized mixture obtained in step (4). The neutralized mixture obtained in step (4) may contain bubbles generated by stirring or the like. In step (5), this mixture is defoamed to obtain liquid soap. For example, the time for defoaming by leaving it to stand can be appropriately selected depending on the viscosity of the liquid soap. For example, in the case of liquid soap with the formulation shown in the examples, it can be defoamed by leaving it to stand for one hour or more. Furthermore, any means can be used to defoam the liquid soap.

[0039] (Oil (A)) The oil used in the present invention is not particularly limited, and may be derived from, for example, plants or animals. The oil used in the present invention may contain, for example, a triglyceride (triacylglycerol), which is a compound of fatty acid and glycerin, and may be, for example, a fat or oil. The oil used in the present invention may be composed of a single triglyceride or a mixture of multiple types of triglycerides.

[0040] Examples of oils and fats that can be used include edible oils and fats and industrial oils and fats. The oils and fats may be derived from either plants or animals. Liquid fats or solid fats with a freezing point near room temperature are preferred, and combinations of these may also be used. Examples of plant-derived oils and fats include salad oil, canola oil, corn oil, soybean oil, sesame oil, rapeseed oil, perilla oil, olive oil, linseed oil, camellia oil, rice bran oil, safflower oil, palm oil, palm kernel oil, sunflower oil, grape oil, cottonseed oil, coconut oil, peanut oil, castor oil, and tall oil. Animal-derived oils and fats are often solid fats with high freezing points and often do not blend well with liquid soap when used alone. Therefore, they are preferably combined with plant-derived oils and fats. Furthermore, fish oil, a liquid fat, may be unsuitable for liquid soap because it contains a large amount of highly unsaturated fatty acids and unsaponifiable matter, which are prone to spoilage.

[0041] The oil used in the present invention may be one of the above-mentioned fats and oils, or may contain two or more of them. From the viewpoint of producing liquid soap, the oil is preferably a liquid fat alone or a combination of two or more fats and oils including at least a liquid fat.

[0042] The oil used in the present invention may contain a fatty acid. The fatty acid may be, for example, a fatty acid produced by the decomposition of fats and oils. The fatty acid is not particularly limited, but may be, for example, saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid; unsaturated fatty acids such as palmitoleic acid, oleic acid, icosenoic acid, linoleic acid, α-linolenic acid, and γ-linolenic acid; etc. Of these, saturated fatty acids that are solid fats at room temperature are preferably used in combination with other liquid fats (for example, unsaturated fatty acids) from the perspective of producing liquid soap. Unsaturated fatty acids that are liquid fats at room temperature may be used alone or in combination of two or more types.

[0043] The oil used in the present invention may be new oil (new oil) or used oil. The oil used in the present invention may also be waste oil, for example. By using waste oil in the present invention, it is possible to effectively utilize waste oil that has previously been incinerated or disposed of.

[0044] Waste oil may be, for example, oil used in ordinary households, or oil generated during business activities, such as industrial waste. Examples of waste oil include waste cooking oil and industrial waste oil. Waste cooking oil includes commercial waste cooking oils used in restaurants and food factories, as well as waste cooking oils used in ordinary households. Industrial waste oil includes kerosene, light oil, and heavy oil that has been used or deteriorated due to long-term storage. However, these non-glyceride hydrocarbon waste oils are not used because they cannot be made into soap. A mixture of waste oil and new oil is also acceptable.

[0045] The amount of oil in the liquid soap produced is not particularly limited, but for example, if the liquid soap produced is taken as 100% by weight, it can be 10 to 50% by weight, preferably 15 to 40% by weight, and more preferably 20 to 35% by weight.

[0046] (Ethyl alcohol (B, B1)) Ethyl alcohol can also be called ethanol. The use of ethyl alcohol can accelerate the saponification reaction in step (2). Therefore, in the present invention, liquid soap can be produced in a short time even if step (2) is carried out without heating.

[0047] The ethyl alcohol used in the present invention may be 100% ethyl alcohol or a composition containing ethyl alcohol and other components. The ethyl alcohol may be, for example, a fermented alcohol obtained by fermenting a carbohydrate material or a starchy material, or a synthetic alcohol.

[0048] The composition containing ethyl alcohol and other ingredients may be, for example, an alcoholic preparation containing ethyl alcohol as the main ingredient. Alcoholic preparations are classified into pharmaceuticals, quasi-drugs, cosmetics, alcoholic beverages, food additives, miscellaneous goods, etc. depending on the ingredients other than ethyl alcohol and their intended use. The ethyl alcohol used in the present invention may be an alcoholic preparation classified into any of these categories.

[0049] The alcohol preparation used in the present invention may be, for example, a disinfectant alcohol for sterilizing or disinfecting skin such as the hands, instruments, or objects, or an alcohol preparation (food additive) for sterilizing or disinfecting food, cooking utensils, cooking equipment, etc.

[0050] The alcoholic preparation may contain water and additives as components other than ethyl alcohol. These other components include, but are not limited to, adipic acid, citric acid, trisodium citrate, phosphoric acid, phosphates, glycine, glycerin fatty acid esters, gluconodeltalactone, gluconic acid, sodium gluconate, acetic acid, sodium acetate, carbon dioxide, lactic acid, sodium lactate, succinic acid, monosodium succinate, disodium succinate, DL-tartaric acid, L-tartaric acid, sodium DL-tartrate, sodium L-tartrate, carbonates, fumaric acid, monosodium fumarate, lysozyme, DL-malic acid, sodium DL-malate, itaconic acid, and phytic acid. The alcoholic preparation may contain only one of these components or a combination of two or more of them.

[0051] The ethyl alcohol used in the present invention may be denatured alcohol. Denatured alcohol is ethanol to which a denaturant has been added to prevent its diversion into food and beverages. The use of denatured alcohol allows for cost reduction because it is exempt from alcohol tax. The denaturant may be any component that can prevent its diversion into food and beverages, and is not particularly limited. Examples of the denaturant include various fragrances such as geraniol, which smells like rose, and linalyl acetate, which smells like lavender.

[0052] Furthermore, the ethyl alcohol used in the present invention is not limited to those mentioned above, but may also be, for example, alcoholic beverages for food use.

[0053] As the ethyl alcohol used in the present invention, two or more of the above-mentioned compositions may be used in combination.

[0054] When the ethyl alcohol used in the present invention is a composition with other components, the content of ethyl alcohol in the composition is not particularly limited, but may be, for example, 99% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, or less than 60% by weight, and is preferably less than 60% by weight. If the ethyl alcohol content in the composition is less than 60% by weight, it does not fall under the hazardous material defined by the Fire Service Act and is easy to obtain and store. In addition, the lower limit of the ethyl alcohol content in the composition is not particularly limited, but may be, for example, 30% by weight or more, 50% by weight or more, or 55% by weight or more.

[0055] The amount of ethyl alcohol in the liquid soap produced is not particularly limited, but for example, if the liquid soap produced is taken as 100% by weight, the amount of ethyl alcohol in 100% may be 5 to 35% by weight, preferably 8 to 30% by weight, and more preferably 10 to 25% by weight.

[0056] (Water (C, C1)) The water used in the present invention is not particularly limited, and can be, for example, purified water, distilled water, ion-exchanged water, tap water, or natural water such as well water. However, tap water and natural water with a high hardness (hard water = hardness of 120 or more) should not be used because they contain large amounts of calcium and magnesium, which inhibit the detergency of soap.

[0057] The amount of water in the liquid soap to be produced is not particularly limited, but may be 35 to 85% by weight, and preferably 40 to 70% by weight, assuming that the liquid soap to be produced is 100% by weight. The water referred to here includes not only water (C, C1) but also water that may be contained in other components such as ethyl alcohol (B, B1).

[0058] (Base (D)) A base can also be called an alkali, and is a substance that exhibits basicity with a pH greater than 7 when dissolved in water, and is capable of saponifying fats and oils.

[0059] As the base, an inorganic base or an organic base can be used, preferably an inorganic base, more preferably potassium hydroxide, which is an alkali metal hydroxide.

[0060] The base may be used after being dissolved in water or the like, or may be added directly without being dissolved. When the base is added directly without being dissolved, a container for dissolving the base is not required.

[0061] The amount of base to be blended in the liquid soap to be produced is not particularly limited as long as it is an amount that can sufficiently saponify the oils and fats, but for example, it can be approximately 2 to 15% by weight, where the liquid soap to be produced is 100% by weight.

[0062] (acid(E)) The acid is not particularly limited as long as it can neutralize the base (D), but examples thereof include acetic acid, citric acid, malic acid, glycolic acid, succinic acid, fumaric acid, and lactic acid. Citric acid is preferred for use in the present invention because it is inexpensive and easily available. The acid is preferably an organic acid. When using inorganic acids such as hydrochloric acid, the salts produced by neutralizing the base may impair the stability of the liquid soap.

[0063] The amount of acid to be blended in the liquid soap to be produced can be set appropriately depending on the amount of excess base, and is not particularly limited, but for example, when the liquid soap to be produced is taken as 100% by weight, it can be 0.01 to 5% by weight, preferably 0.05 to 3% by weight, and more preferably 0.1 to 2% by weight.

[0064] (Other ingredients) The method for producing liquid soap of the present invention may include a step of adding other components in addition to components (A) to (E), provided that the effects of the invention are not impaired. Examples of such other components include, but are not limited to, anionic surfactants, amphoteric surfactants, nonionic surfactants, humectants, preservatives, colorants, moisturizers, chelating agents, UV absorbers, medicinal agents, and fragrances. These may be used alone or in combination of two or more.

[0065] The step of adding other components can be carried out after step (4), and the other components can be added alone.

[0066] In the manufacturing method of the present invention, although not particularly limited, liquid soap can be manufactured using only one container. For example, in step (1), oil, ethyl alcohol, and a base are added to a container, the mixture is stirred in the container in step (2) to cause a saponification reaction, the mixture is mixed and diluted in step (3), an acid is added to the container in step (4) to neutralize, and the mixture is left to stand and degassed in step (5). The container may be, for example, a container that can be used in a mixer.

[0067] [Liquid soap] The liquid soap obtained by the production method of the present invention is in a liquid form. In this specification, "liquid form" includes gel, jelly, slime, foam, etc.

[0068] The liquid soap obtained by the production method of the present invention is not particularly limited, but can contain 10 to 40% by weight, preferably 15 to 35% by weight, of fatty acid salt as the main component.

[0069] Liquid soap obtained by the production method of the present invention, for example, waste oil liquid soap produced using waste oil, can be laundry soap, kitchen soap, industrial soap, etc. Liquid soap produced using unused new oil can be used for cosmetics, quasi-drugs, pharmaceuticals, etc. that are applied directly to the skin. Liquid soap produced using the present invention may not be for sale and may be produced and used at home, for example.

[0070] [kit] The present invention also provides a kit for producing liquid soap. The kit of the present invention comprises ethyl alcohol (B), a base (D), and an acid (E). The kit of the present invention may further comprise ethyl alcohol (B1). The kit of the present invention can be used to carry out the above-described method for producing liquid soap.

[0071] The ethyl alcohol may be one of the above-described embodiments. In the kit of the present invention, the ethyl alcohol may be, for example, denatured alcohol or an alcohol preparation containing less than 60% by weight of ethyl alcohol. Denatured alcohol is exempt from liquor tax, thereby reducing costs. Furthermore, if the ethyl alcohol content is less than 60% by weight, it is not considered a hazardous material under the Fire Service Act and is easy to obtain and store.

[0072] The base may be one of the above-described embodiments. In the kit of the present invention, the base may be, for example, a hydroxide salt of an alkali metal or alkaline earth metal, preferably potassium hydroxide. The base may be a simple base or may be in the form of an aqueous solution. The base may further contain other components.

[0073] The acid may be any of the above-described embodiments. In the kit of the present invention, the acid may be, for example, acetic acid, citric acid, malic acid, glycolic acid, succinic acid, fumaric acid, lactic acid, etc., and is preferably citric acid. The acid may be a simple acid or may be in the form of an aqueous solution. The acid may further contain other components.

[0074] The kit of the present invention may further include substances other than ethyl alcohol (B, B1), base (D), and acid (E), such as a container for mixing and stirring, a stirrer, pH test paper for measuring pH, and instructions for use.

[0075] The kit of the present invention may be a kit for producing liquid soap using waste oil. The kit of the present invention may be a kit for producing liquid soap using, for example, used cooking oil at home. By using the kit of the present invention, liquid soap can be produced easily at home in a short time and at low cost. [Example]

[0076] The present invention will be further described below using examples, but the present invention is not limited to these. Unless otherwise specified, "%" means "% by weight."

[0077] Example 1 Liquid soap was prepared by the following method.

[0078] A tabletop mixer (8 L large capacity; Xverycan) was used for the production. The blending amounts of each raw material are shown in Table 1.

[0079] The waste oil (component (A)) used was edible blended oil (edible rapeseed oil, edible soybean oil) sold by Taisei Bussan Co., Ltd. and manufactured by J-Oil Mills. The alcohol preparation (component (B, B1)) used was Mayall (W65n 20L; 65% by volume (less than 60% by weight) of rubbing alcohol; manufactured by Mitsubishi Corporation Life Sciences Co., Ltd.). Tap water was used for water (component (C, C1)). Commercially available potassium hydroxide (component (D)) and citric acid (component (E)) were used.

[0080] First, 1. waste oil, 2. alcohol preparation, 3. tap water, and 4. potassium hydroxide were added to the container of a tabletop mixer in this order (step (1)). At this time, the concentration of the potassium hydroxide solution was 30%.

[0081] Next, the container was placed in a tabletop mixer, the lid was closed, and the opening was covered with plastic wrap. Mixing was started using the whipper-type mixing blade shown in Figure 3, with speed adjustment set to No. 3 of the six speed settings. Mixing was continued for approximately 1 hour without heating, allowing the saponification reaction to occur (Step (2)). During this time, heat of dissolution of potassium hydroxide in water was generated, and the temperature rose to approximately 50-60°C 5 minutes after the start of mixing.

[0082] Next, the viscosity of the soap increased during the saponification process, and to reduce the viscosity and dilute the soap, which had become paste-like or creamy, 5. Alcohol preparation and 6. Tap water were added (step (3)). 5. Alcohol preparation was added at normal speed and stirred at speed No. 3 for approximately 5 to 7 minutes. Next, 6. Tap water was added all at once and stirred at speed No. 3 for 3 minutes to dilute, after which the rotation speed was reduced to No. 2 and the stirring was continued for 5 minutes. Care was taken when adding the tap water gradually, as the mixture would suddenly change from a paste-like state to a hard gel-like state, making stirring impossible. The stirring time after adding the tap water was approximately 8 to 10 minutes. Care was taken, as stirring beyond this time would increase the amount of soap foam and prolong the defoaming time.

[0083] Then, while measuring the pH, citric acid (a food additive) was added to neutralize the excess alkali and adjust the pH to about 9.5 to 11.0 (step (4)), and finally the mixture was left to stand and degassed (step (5)). Through these steps, a liquid soap was produced.

[0084] The concentration of the produced liquid soap was about 30%, and the alcohol concentration was about 15%. The liquid soap was a flowable, brown, transparent liquid.

[0085] [Table 1]

[0086] Example 2 Next, liquid soap was produced using waste oil containing oils that are difficult to make transparent, such as rice bran oil or sesame oil. For production, the same tabletop mixer as in Example 1 was used. The blending amounts of each raw material are shown in Table 2.

[0087] Waste rice bran oil obtained from the Shibuya Fureai Botanical Center was used as the waste oil (component (A)). The alcohol preparation, potassium hydroxide, and citric acid used were the same as those used in Example 1.

[0088] First, 1. waste oil, 2. alcohol preparation, 3. tap water, and 4. potassium hydroxide were added to the container of a tabletop mixer in this order (step (1)). At this time, the concentration of the potassium hydroxide solution was 30%.

[0089] Next, the container was placed in a tabletop mixer and mixed and stirred for about 1 hour without heating to cause a saponification reaction (step (2)). During this time, heat of dissolution of potassium hydroxide in water was generated, and the temperature rose to approximately 50-60°C 5 minutes after the start of stirring.

[0090] Next, 5. the alcohol preparation and 6. tap water were added and stirred in the same manner as in Example 1 to dilute the mixture (step (3)).

[0091] Then, while measuring the pH, citric acid (a food additive) was added to neutralize the excess alkali and adjust the pH to about 9.5 to 11.0 (step (4)), and finally the mixture was left to stand and degassed (step (5)). Through these steps, a liquid soap was produced.

[0092] The concentration of the produced liquid soap was about 25%, and the alcohol concentration was about 12.5%. The liquid soap was a brown, transparent liquid.

[0093] [Table 2]

[0094] (Quality evaluation) The quality of the liquid soap of Example 2 was evaluated by eight panelists at the Shibuya Fureai Botanical Center. Specifically, using the questionnaire shown in Figure 2, the liquid soap was evaluated for its "cleaning power," "cleaning stamina," "oil residue," "skin moisturizing," and "skin irritation."

[0095] (Each evaluation method) For "cleaning power," the higher the cleansing power, the better the rating. For "cleaning stamina," the longer the cleansing power lasted, the better the rating. For "oil residue," a poor rating was given if oil remained after washing away oily stains, and a good rating was given if no oil remained. For "skin moisturization," a good rating was given if the skin felt very moist after using the liquid soap. For "skin irritation," a poor rating was given if the liquid soap was too irritating to the skin during or after use, and a good rating was given if the irritation was mild.

[0096] For the relative evaluation, the liquid soap was used as a kitchen soap and its "cleaning power," "cleaning stamina," "leakage of oil," "moisturizing effect on skin," and "irritation to skin" were evaluated on a five-point scale: good (+2), somewhat better (+1), the same (0), somewhat bad (-1), and bad (-2) compared to the detergent they normally use, and the average of each panel's evaluation results was calculated.

[0097] For the absolute evaluation, the liquid soap was used as a kitchen soap and its "cleaning power," "cleaning stamina," "leakage," "moisturizing effect on skin," and "irritation to skin" were evaluated on a five-point scale: good (+2), somewhat good (+1), the same (0), somewhat bad (-1), and bad (-2) in comparison with their ideal detergent. The average of each panel's evaluation results was then calculated.

[0098] The results of the relative and absolute evaluations of the liquid soap of Example 2 are shown in Figure 1. The liquid soap of Example 2 received high ratings in all categories, including "cleaning power," "cleaning power stamina," "oil residue," "difference in moisturizing effect on skin," and "skin irritation," with both the relative and absolute ratings of 0 or higher. Furthermore, the rating for "skin irritation" was particularly high, and the rating for "difference in moisturizing effect on skin" was also excellent, indicating that the liquid soap of Example 2 is gentle on the skin. The relative rating for "oil residue" was also excellent. [Industrial Applicability]

[0099] The present invention can be suitably used in the production of liquid soap.

Claims

1. Step (1) of adding ethyl alcohol (B), water (C) and a base (D) to oil (A); Step (2) of stirring the mixture of step (1) to cause a saponification reaction; (3) diluting the mixture after the saponification reaction by adding either or both of ethyl alcohol (B1) and water (C1); Step (4) of neutralizing by adding an acid (E); A degassing step (5); A method for producing liquid soap comprising the steps of:

2. A method for producing liquid soap according to claim 1, wherein the oil (A) is waste oil.

3. A method for producing liquid soap according to claim 1 or 2, wherein the ethyl alcohol (B) is a denatured alcohol or an alcohol preparation containing less than 60% by weight of ethyl alcohol.

4. 3. A method for producing liquid soap according to claim 1 or 2, wherein the saponification reaction is carried out without heating in step (2).

5. the base (D) is potassium hydroxide, and A method for producing liquid soap according to claim 1 or 2, wherein the acid (E) is citric acid.

6. A kit for producing liquid soap, comprising ethyl alcohol (B), a base (D), and an acid (E).

7. The ethyl alcohol (B) is a denatured alcohol or an alcohol preparation containing less than 60% by weight of ethyl alcohol, 7. The kit of claim 6, wherein the base (D) is potassium hydroxide.

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