Acidic CIP cleaning agent composition, method for using the acidic CIP cleaning agent composition, and method for cleaning inorganic stains

Abstract

Provided is a detergent composition that does not contain phosphorus and has excellent detergency for sparingly soluble calcium and for iron oxide. The acidic CIP cleaning agent composition according to the present disclosure is a phosphorus-free cleaning agent composition, and contains 10 to 40 parts by mass of nitric acid, 0.3 to 3 parts by mass of oxalic acid, and water.

Description

[Technical field]

[0001] The present disclosure relates to a cleaning agent composition that can be used for CIP cleaning of various production lines in dairy, beverage, and food processing plants. [Background technology]

[0002] In dairy and food and beverage factories, acidic cleaners are used to remove poorly soluble calcium stains that adhere to manufacturing equipment. The main components include nitric acid, phosphoric acid, and organic acids. Among them, mixed acid cleaners that combine nitric acid and phosphoric acid are widely used because they are excellent not only for poorly soluble calcium stains but also for iron oxide (so-called iron rust). For example, Patent Document 1 discloses a cleaner composition that contains nitric acid and phosphoric acid and has excellent cleaning properties for organic and inorganic stains, low foaming properties, rubber corrosion prevention properties, and storage stability at low and high temperatures (paragraph 0009).

[0003] Nitric acid is an inexpensive raw material that has excellent cleaning properties for poorly soluble calcium stains. However, it has poor cleaning properties for iron oxide. In addition, high concentrations of nitric acid are likely to generate toxic nitric acid gas, which is harmful to the human body. Phosphoric acid is effective at cleaning iron oxide, but is somewhat inferior at cleaning insoluble calcium stains. In addition, the price of phosphoric acid has risen sharply in recent years due to the influence of the global situation, and it has an impact on the environment, such as eutrophication, when discharged into rivers and oceans. Furthermore, as mentioned above, the mixed acid system of nitric acid and phosphoric acid has satisfactory cleaning performance for iron oxide and sparingly soluble calcium stains, but is economically undesirable because it contains phosphoric acid. Organic acids are sometimes used instead of phosphoric acid in places where phosphorus discharge regulations are in place, but their cleaning performance for iron oxide and sparingly soluble calcium stains is low. In addition, organic acids generally have high BOD (biochemical oxygen demand) and COD (chemical oxygen demand), so there is a problem that using large amounts of them increases the load on wastewater treatment facilities. Oxalic acid is known as an acid with high cleaning properties for iron oxide. However, the solubility of oxalic acid at 0°C is 3.416 g per 100 g of water (Non-Patent Document 1), and there is a problem in that the use of oxalic acid results in poor storage stability at low temperatures.

[0004] Furthermore, stainless steel is widely used as the metal material for manufacturing equipment in dairy and food and beverage factories, etc. Patent Document 2 discloses an odorless cleaner for stainless steel, but although the acid ammonium fluoride used in the cleaner is excellent at removing iron rust, it has a large effect on the human body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-074966 A [Patent Document 2] JP 2006-249488 A [Non-patent literature]

[0006] [Non-Patent Document 1] Iwanami Dictionary of Physics and Chemistry, 4th Edition, Iwanami Shoten Co., Ltd., page 582 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above circumstances, an object of the present disclosure is to provide a detergent composition that does not contain phosphorus and has excellent detergency for poorly soluble calcium and excellent detergency for iron oxide. [Means for solving the problem]

[0008] In order to solve the above problems, the inventors of the present application have conducted extensive research into a phosphorus-free detergent that is highly effective in cleaning iron oxide and poorly soluble calcium stains, and is also excellent in low-temperature storage stability, stainless steel corrosion prevention, safety, and economic efficiency. As a result, they have found that the above problems can be solved by combining nitric acid and oxalic acid in a specific ratio, and have completed the present invention.

[0009] The acidic CIP cleaning agent composition according to the first embodiment of the present disclosure is a phosphorus-free cleaning agent composition, and contains 10 to 40 parts by mass of nitric acid, 0.3 to 3 parts by mass of oxalic acid, and water. By configuring in this manner, it is possible to obtain a detergent composition having high detergency against iron oxide and sparingly soluble calcium stains.

[0010] The acidic CIP cleaning agent composition according to the second embodiment of the present disclosure is a phosphorus-free cleaning agent composition, and contains 10 to 40 mass % of nitric acid, 0.3 to 3 mass % of oxalic acid, and water in a total amount of 100 mass %. By configuring in this manner, a detergent composition having high detergency against iron oxide and sparingly soluble calcium stains can be obtained.

[0011] The acidic CIP cleaning composition according to the third aspect of the present disclosure is the acidic CIP cleaning composition according to the first or second aspect, and consists only of the nitric acid, the oxalic acid, and the water. By configuring in this manner, a detergent composition having high detergency against iron oxide and sparingly soluble calcium stains can be obtained.

[0012] The acidic CIP cleaning composition according to a fourth aspect of the present disclosure is a cleaning composition according to any one of the first to third aspects, in which the acidic CIP cleaning composition is diluted with water or hot water to a concentration of 0.1 to 50 mass %. By configuring in this way, it is possible to obtain a cleaning composition that is suited to the application, such as the degree of dirt.

[0013] A method for using the acidic CIP cleaning composition according to the fifth aspect of the present disclosure is a method in which the acidic CIP cleaning composition according to the fourth aspect is heated to 20 to 85°C and used. By configuring in this way, a more effective method of using the cleaning composition can be obtained.

[0014] A cleaning method for inorganic stains according to a sixth aspect of the present disclosure is a method for removing inorganic stains from a metal surface by using the acidic CIP cleaning agent composition according to any one of the first to fourth aspects. With this configuration, inorganic dirt can be removed without corroding the metal surface.

[0015] A method for cleaning inorganic soil according to a seventh aspect of the present disclosure is the method for cleaning inorganic soil according to the sixth aspect, wherein the inorganic soil contains sparingly soluble calcium or iron rust. With this configuration, poorly soluble calcium or iron rust can be effectively removed.

[0016] A method for cleaning inorganic soil according to an eighth aspect of the present disclosure is the method for cleaning inorganic soil according to the sixth or seventh aspect, wherein the metal constitutes production equipment of a dairy product and food and beverage production plant. With this configuration, inorganic dirt adhering to manufacturing equipment in dairy and food and beverage factories can be removed. Effect of the Invention

[0017] The present disclosure makes it possible to provide a detergent composition that does not contain phosphorus and has excellent detergency for poorly soluble calcium and excellent detergency for iron oxide. [Brief description of the drawings]

[0018] [Figure 1] 1 is a table showing the evaluation methods of various tests carried out in the examples. [Diagram 2] 1 is a table showing the compounding ratios and test results of Examples 1-8. [Diagram 3] 1 is a table showing the compounding ratios and test results of Comparative Examples 1-11. [Figure 4] 1 is a table showing the compounding ratios and test results of Comparative Examples 12-17. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiment.

[0020] In this specification, "CIP (Cleaning in Place)" refers to cleaning in place. Cleaning in place is a method of cleaning equipment while it remains in nearly the same condition as when it was in operation, without disassembling or moving it. "Phosphorus-free" means not containing phosphorus. "Inorganic soil" refers to soil caused by or formed from inorganic matter. "Slightly soluble calcium" refers to calcium that has combined with other ions to form a compound that is less soluble in water (e.g., calcium phosphate).

[0021] [Acid CIP cleaning agent composition] The present disclosure relates to a phosphorus-free cleaning composition for acidic CIP, which contains 10 to 40 parts by mass of nitric acid, 0.3 to 3 parts by mass of oxalic acid, and water. The cleaning composition for acidic CIP may be a cleaning composition consisting of only the nitric acid, the oxalic acid, and the water.

[0022] The amount of nitric acid contained in the acidic CIP cleaning composition is preferably 10 to 40 parts by mass, more preferably 15 to 38 parts by mass, 20 to 37 parts by mass, or 25 to 36 parts by mass, and particularly preferably 30 to 35 parts by mass. When the amount is 10 parts by mass or more, sufficient cleaning performance for poorly soluble calcium can be obtained. When the amount is 40 parts by mass or less, the amount of toxic nitric acid gas generated can be suppressed. Alternatively, when the total amount of nitric acid, oxalic acid, and water is 100% by mass, the amount of nitric acid contained in the acidic CIP cleaning agent composition is preferably 10 to 40% by mass, more preferably 15 to 38% by mass, 20 to 37% by mass, or 25 to 36% by mass, and particularly preferably 30 to 35% by mass.

[0023] The amount of oxalic acid (not including water molecules) contained in the acidic CIP cleaning agent composition is preferably 0.3 to 3 parts by mass, more preferably 0.5 to 2.5 parts by mass, and particularly preferably 1 to 2 parts by mass. When it is 0.3 parts by mass or more, sufficient cleaning properties for iron oxide can be obtained. When it is 3 parts by mass or less, a decrease in low-temperature storage stability can be avoided. The oxalic acid used may be a hydrate or an anhydride. Alternatively, when the total amount of nitric acid, oxalic acid, and water is 100% by mass, the amount of oxalic acid contained in the acidic CIP cleaning agent composition is preferably 0.3 to 3% by mass, more preferably 0.5 to 2.5% by mass, and particularly preferably 1 to 2% by mass.

[0024] The water contained in the acidic CIP cleaning agent composition is the water contained in oxalic acid when oxalic acid is a hydrate, or the water added together with nitric acid or oxalic acid when the acid is an aqueous solution, or the water added separately. The water may be ion-exchanged water, soft water, pure water, tap water, or the like, and is not particularly limited. The amount of water contained can be adjusted by dilution depending on the type and degree of dirt. For example, the acidic CIP cleaning agent composition may be diluted to 0.1 to 50 mass %.

[0025] Furthermore, other components commonly used in the art may be added to the composition as long as they do not impair the effects of the acidic CIP cleaning agent composition, such as other acid components (e.g., citric acid, sulfamic acid, sulfuric acid, etc.), metal corrosion inhibitors, surfactants, defoamers, hydrotropes, thickeners, fragrances, colorants, pH adjusters, etc.

[0026] The acidic CIP cleaning agent composition according to the present disclosure can be used for cleaning manufacturing equipment used in dairy and food and beverage factories, and can be used as a CIP cleaning agent when cleaning the inside of the manufacturing equipment without disassembling it. Stainless steel, titanium, etc. are used as metal materials for these manufacturing equipment. The acidic CIP cleaning agent composition according to the present disclosure contains oxalic acid, but can be used without corroding these metal materials.

[0027] The acidic CIP cleaning agent composition according to the present disclosure can effectively remove inorganic dirt. Inorganic dirt includes poorly soluble calcium and iron rust. Examples of poorly soluble calcium include calcium phosphate, calcium oxalate, and calcium sulfate.

[0028] [Manufacturing method] The acidic CIP cleaning agent composition according to the present disclosure can be obtained by measuring nitric acid and oxalic acid so that the amount of nitric acid is 10 to 40 parts by mass and the amount of oxalic acid is 0.3 to 3 parts by mass, diluting the mixture with water, and mixing the mixture.

[0029] The acidic CIP cleaning agent composition according to the present disclosure may be used at room temperature (20° C.) or after heating. When heated, the temperature is preferably 20 to 85° C., more preferably 60 to 75° C. The temperature may be adjusted to the above range by diluting with hot water (warm water).

[0030] As described above, by combining nitric acid and oxalic acid in the above-mentioned mixing ratio, an acidic CIP cleaning agent composition effective for cleaning iron oxide and sparingly soluble calcium stains can be obtained. Furthermore, by minimizing the amount of oxalic acid, a cleaning agent having excellent low-temperature storage stability and high corrosion prevention properties for stainless steel can be obtained. In addition, since it generates less nitric acid gas than conventional nitric acid-phosphoric acid mixed acid cleaning agents, it has been confirmed to be a cleaning agent with excellent safety during cleaning operations. EXAMPLES

[0031] The present disclosure will be specifically described below with reference to examples and comparative examples. However, the present disclosure is not limited to the contents described in the following examples.

[0032] The reagents and their concentration ranges used in the examples and comparative examples are shown below. Nitric acid: Nissan Chemical (active ingredient 67.5%) Oxalic acid dihydrate: manufactured by Hishio Chemical Co., Ltd. Phosphoric acid: Nippon Chemical Industry Co., Ltd. (active ingredient 75%) Anhydrous citric acid: Fuso Chemical Co., Ltd.

[0033] [Preparation of cleaning composition] Examples 1-8, Comparative Examples 1-17 For Examples 1 to 8, cleaning compositions were prepared based on the blending ratios shown in Table 2 in Figure 2. For Comparative Examples 1 to 11, cleaning compositions were prepared based on the blending ratios shown in Table 3 in Figure 3, and for Comparative Examples 12 to 17, cleaning compositions were prepared based on the blending ratios shown in Table 4 in Figure 4. Note that, in the blending ratios in Tables 2 to 4, nitric acid is expressed in terms of pure content, and oxalic acid is expressed in terms of mass% concentration of oxalic acid dihydrate.

[0034] [Iron oxide cleaning test] (Test Method) A cleaning test was carried out using iron (III) oxide (Kanto Chemical Co., Ltd.). In a 50 ml conical beaker, 50 ml of a 10% by mass aqueous solution of the cleaning composition of Examples 1-8 and Comparative Examples 1-17 was prepared with ion-exchanged water and heated to 70°C. 50 mg of iron (III) oxide was added thereto and immersed for 90 minutes (shaking and mixing was performed every 30 minutes). Thereafter, the mixture was filtered through a 0.45 μm syringe filter, and the concentration of iron ions in the filtrate was measured by ICP (inductively coupled plasma) emission spectroscopy, and the cleaning property of the iron oxide was evaluated according to the following criteria.

[0035] (Evaluation Criteria) ◎: Dissolution rate of 10 ppm or more ○: Dissolution rate between 5 ppm and 10 ppm △: Dissolution rate of 1 ppm or more but less than 5 ppm ×: Dissolution rate of less than 1 ppm Products with the evaluation criteria of ◎ and ◯ were judged to be practical.

[0036] [Washing test for poorly soluble calcium] (Test Method) A cleaning test was carried out using calcium phosphate (trade name: Apatite β-TCP, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as poorly soluble calcium stains. 300 ml of 1% by mass aqueous solutions of the detergent compositions of Examples 1-8 and Comparative Examples 1-17 were prepared with ion-exchanged water in a 300 ml glass beaker and heated to 70°C. 300 mg of calcium phosphate was added thereto and stirred for 20 minutes. The solution was filtered through a 0.45 μm syringe filter, and the concentration of calcium ions in the filtrate was measured by ion chromatography, and the cleaning ability of poorly soluble calcium stains was evaluated according to the following criteria.

[0037] The dissolution rate of calcium phosphate was calculated from the following formula. Dissolution rate (%)= {(amount of calcium phosphate added - amount of calcium phosphate remaining after washing) / (amount of calcium phosphate added)} x 100 (Evaluation Criteria) ◎: Dissolution rate of 95% or more 〇: Dissolution rate is 80% or more and less than 95% △: Dissolution rate is 60% or more and less than 80% ×: Dissolution rate less than 60% Products with the evaluation criteria of ◎ and ◯ were judged to be practical.

[0038] [Low temperature storage stability] (Test Method) 100 ml of a 100% by mass aqueous solution of the cleaning composition of each of Examples 1-8 and Comparative Examples 1-17 was placed in a 100 ml polyethylene container and stored in an incubator set at -5°C for 30 days. The presence or absence of precipitates and freezing was visually confirmed to evaluate the storage stability according to the following criteria.

[0039] (Evaluation Criteria) ◯: No precipitation or freezing was observed. △: A small amount of precipitate was generated. ×: A large amount of precipitate was generated or the mixture was frozen. Products with evaluation criteria of ◯ and △ were judged to be practical.

[0040] [Stainless steel corrosion prevention test] (How to make test pieces) A test piece (SUS304, 50 mm x 100 mm x 1 mm) was washed with a neutral detergent, rinsed with ion-exchanged water, and degreased with petroleum ether.

[0041] (Test Method) 300 ml of a 100% by mass aqueous solution of the cleaning composition of Examples 1-8 and Comparative Examples 1-17 was placed in a 300 ml glass beaker and heated to 50° C. The test piece was completely immersed in the solution for 72 hours. The test piece was taken out, rinsed with ion-exchanged water, and degreased with petroleum ether. The change in the appearance of the test piece was visually observed and evaluated according to the following criteria.

[0042] (Evaluation Criteria) ○: No discoloration ×: Discoloration Products that met the evaluation criteria of ◯ were judged to be practical.

[0043] [Nitric acid gas generation test] (Test Method) 100 ml of a 100% by mass aqueous solution of the cleaning composition of Example 1-8 or Comparative Example 1-17 was placed in a 1 L polyethylene container with a hole in the lid, and allowed to stand for 48 hours at 25° C. Thereafter, the lid of the container was opened, and the amount of nitric acid gas generated was measured using a detector tube (manufactured by Gastec, nitric acid 15 L, measurement range 0.1 to 40 ppm), and evaluated according to the following criteria.

[0044] (Evaluation Criteria) ◎: Less than 10 ppm ○: 10 ppm or more, less than 20 ppm △: 20 ppm or more, less than 30 ppm ×: 30ppm or more The evaluation criteria of ◎, ◯, and △ were judged to be practical.

[0045] Examples 1-8 are excellent not only in cleaning ability against iron oxide and poorly soluble calcium, but also in low-temperature storage stability and corrosion prevention against stainless steel, and furthermore, can suppress the generation of nitric acid gas and does not contain phosphorus. These characteristics are effective for CIP cleaning of various production lines in dairy, beverage, and food processing plants. Furthermore, Examples 1-8 are cleaning compositions containing nitric acid and oxalic acid. On the other hand, Comparative Example 12 is a cleaning composition containing conventional nitric acid and phosphoric acid. Comparing the test results of Examples 1-8 and Comparative Example 12, it can be seen that Examples 1-8 have the same effect as Comparative Example 12 or are superior to Comparative Example 12. For example, Examples 2, 5, and 8 have a higher number of ◎ than Comparative Example 12. Thus, Examples 1-8 show that a cleaning composition containing nitric acid and oxalic acid can be used as a cleaning composition that replaces a conventional cleaning composition containing nitric acid and phosphoric acid.

[0046] In Comparative Example 1-3, the cleaning performance of iron oxide is insufficient because of the small amount of oxalic acid. In addition, as the amount of nitric acid increases, the cleaning performance of poorly soluble calcium improves, but the amount of nitric acid gas generated also increases. Similarly, in Comparative Example 4-5, the cleaning performance of iron oxide is insufficient. Comparative Examples 6-11 have sufficient iron oxide cleaning ability, but insufficient cleaning ability for sparingly soluble calcium, insufficient low-temperature storage stability, and high generation of nitric acid gas. Comparative Example 14 uses only nitric acid, and therefore has poor cleaning performance for iron oxide. Comparative Example 15 uses only phosphoric acid, but shows sufficient effect. However, it contains phosphorus. Comparative Example 16 uses only oxalic acid, and therefore has excellent cleaning performance for iron oxide but poor cleaning performance for sparingly soluble calcium. Furthermore, it has poor corrosion prevention performance for stainless steel. As shown in Comparative Example 16, it is generally known that oxalic acid corrodes stainless steel (metal). However, this disclosure shows that oxalic acid can be used as a component of a cleaning agent composition by adjusting it to a specified amount. It is also possible that corrosiveness was suppressed by combining it with nitric acid. Comparative Example 17 uses citric acid as an example of an organic acid, but has poor cleaning performance for iron oxide.

Claims

1. 1. A phosphorus-free cleaning composition comprising: 10 to 40 parts by mass of nitric acid; 0.3 to 3 parts by mass of oxalic acid; Water, (but excluding hydrofluoric acid), Acidic CIP cleaning agent composition.

2. 1. A phosphorus-free cleaning composition comprising: 10 to 40% by mass of nitric acid; 0.3 to 3% by mass of oxalic acid; and water, which totals 100% by mass. Acidic CIP cleaning agent composition.

3. The nitric acid, The oxalic acid, and water, The acidic CIP cleaning agent composition according to claim 1 or 2.

4. The acidic CIP cleaning agent composition according to claim 1 or 2 is diluted with water or hot water to a concentration of 0.1 to 50 mass % for use. Method of using the acidic CIP cleaning agent composition.

5. The diluted acidic CIP cleaning agent composition is heated to 20 to 85°C and used. A method for using the acidic CIP cleaning agent composition according to claim 4.

6. The acidic CIP cleaning agent composition according to claim 1 or 2 is used to remove inorganic dirt from a metal surface. How to clean inorganic stains.

7. The inorganic dirt includes insoluble calcium or iron rust. The method for cleaning inorganic stains according to claim 6.

8. The metal constitutes the manufacturing equipment of dairy and food and beverage manufacturing plants; The method for cleaning inorganic stains according to claim 6.

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