Acidic cleaning solution for aluminum-based metal materials

Abstract

To provide an acidic cleaning solution for aluminum-based metal materials that can achieve desirable cleaning properties while suppressing foaming. [Solution] An acidic cleaning solution for aluminum-based metal materials comprising: 0.01 g / L to 25 g / L of at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid, nitrite, and phosphoric acid; 0.05 g / L to 4.0 g / L of trivalent iron ions; and 0.1 g / L to 10 g / L of a surfactant, wherein the surfactant comprises: surfactant A: a polyoxyalkylene alkyl ether with a cloud point of 80°C or higher; surfactant B: a polyoxyalkylene alkyl ether with a cloud point of 50°C to 60°C; and surfactant C: a polyoxyalkylene alkyl ether with a cloud point of 40°C or lower.

Description

[Technical Field]

[0001] This disclosure relates to an acidic cleaning solution for aluminum-based metal materials. [Background technology]

[0002] Aluminum-based metal materials, manufactured from aluminum or aluminum alloys, generally have aluminum oxides and oils on their surface. Furthermore, aluminum cans, such as beverage cans, manufactured by a drawing and ironing process (hereinafter referred to as DI), have aluminum powder (hereinafter referred to as smut) and lubricating oil adhering to their surface, which are generated when the material is scraped off during the drawing process.

[0003] Typically, aluminum cans, such as beverage cans, are treated with a chemical conversion coating, followed by a paint coating before being put into practical use. To form a strong chemical conversion coating and paint coating, it is necessary to thoroughly remove and clean any aluminum oxides, oils, and smut present on the surface.

[0004] As a method for cleaning the surface of aluminum-based metal materials, for example, Patent Document 1 discloses an invention relating to an acidic cleaning agent for aluminum-based metal materials containing phosphate ions, sulfate ions, and ferric ions. The acidic cleaning agent for aluminum-based metal materials according to Patent Document 1 is described as having good desmutting properties even when cleaning at low temperatures.

[0005] As mentioned above, aluminum cans, such as beverage cans, may have oily substances such as lubricants adhering to them during the manufacturing process. To remove these oily substances, it is effective to include surfactants in the cleaning agent (cleaning solution). A technique has been disclosed for incorporating multiple types of surfactants into a cleaning solution for metal surfaces (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-107576 [Patent Document 2] Special Publication No. 2020-525624 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, when a cleaning solution contains a surfactant, there is a problem that the cleaning solution foams, making the cleaning process difficult. In particular, if foaming of the cleaning solution can be suppressed when performing cleaning treatment at low temperatures, it is desirable because it can reduce the effort and cost when applying the cleaning solution to processes such as manufacturing lines. The technology disclosed in Reference Document 2 is described as having low foaming, but the target of treatment is listed as printed circuit boards (PCBs), and good cleaning performance at high temperatures is a challenge. Therefore, there has been a need for the development of a cleaning solution that can suppress foaming while obtaining desirable cleaning performance when cleaning aluminum-based metal materials at low temperatures.

[0008] The present invention has been made in view of the above, and aims to provide an acidic cleaning solution for aluminum-based metal materials that can achieve desirable cleaning properties while suppressing foaming. [Means for solving the problem]

[0009] (1) This disclosure relates to an acidic cleaning solution for aluminum-based metal materials, comprising: 0.01 g / L to 25 g / L of at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid, nitrite, and phosphoric acid; 0.05 g / L to 4.0 g / L of trivalent iron ions; and 0.1 g / L to 10 g / L of a surfactant, wherein the surfactant comprises: surfactant A: a polyoxyalkylene alkyl ether with a cloud point of 80°C or higher; surfactant B: a polyoxyalkylene alkyl ether with a cloud point of 50°C or higher or 60°C or lower; and surfactant C: a polyoxyalkylene alkyl ether with a cloud point of 40°C or lower.

[0010] (2) The acidic cleaning solution for aluminum-based metal materials according to (1), wherein the surfactant B is poly(oxyethylene oxypropylene) alkyl ether.

[0011] (3) The acidic cleaning solution for aluminum-based metal materials according to (1) or (2), wherein the ratio (MA:MB) of the mass concentration (MA) of surfactant A to the mass concentration (MB) of surfactant B in the acidic cleaning solution for aluminum-based metal materials is 5:1 to 1:6.

[0012] (4) The acidic cleaning solution for aluminum-based metal materials according to any one of (1) to (3), wherein the ratio of the mass of surfactant C (MC) to the sum of the mass of surfactant A (MA) and the mass of surfactant B (MB) (MA+MB) in the acidic cleaning solution for aluminum-based metal materials (MC / (MA+MB)) is 1 / 3 or more.

[0013] (5) The acidic cleaning solution for aluminum-based metal materials according to any one of (1) to (4), wherein the ratio of the mass of surfactant C (MC) to the sum of the mass of surfactant A (MA) and the mass of surfactant B (MB) (MA+MB) in the acidic cleaning solution for aluminum-based metal materials (MC / (MA+MB)) is 1 / 3 or more and 1 or less.

[0014] (6) The acidic cleaning solution for aluminum-based metal materials according to any one of (1) to (5), wherein the inorganic acid contains the phosphoric acid, and the concentration ratio (phosphoric acid:trivalent iron ions) of the mass concentration (g / L) of the phosphoric acid to the mass concentration (g / L) of the trivalent iron ions in the acidic cleaning solution for aluminum-based metal materials is 35:1 to 180:1. [Effects of the Invention]

[0015] According to this disclosure, it is possible to provide an acidic cleaning solution for aluminum-based metal materials that can achieve desirable cleaning performance while suppressing foaming. [Modes for carrying out the invention]

[0016] Hereinafter, embodiments of the present disclosure will be described. The present disclosure is not limited to the description of the following embodiments.

[0017] <Acidic cleaning solution for aluminum-based metal materials> The acidic cleaning solution for aluminum-based metal materials according to the present disclosure (hereinafter, may be referred to as "cleaning solution") contains an inorganic acid, trivalent iron ions, and a surfactant. The inorganic acid and trivalent iron ions are components that promote etching of the aluminum-based metal material to be treated (hereinafter, may be referred to as "metal material"). The surfactant is a component that cleans the oil adhered to the surface of the aluminum-based metal material.

[0018] (Inorganic acid) The inorganic acid is at least one selected from the group consisting of sulfuric acid, nitric acid, nitrous acid, and phosphoric acid. It is preferable that the inorganic acid contains sulfuric acid or phosphoric acid. Sulfuric acid is a strong acid and completely dissociates in water, so it is easy to control the free acid contributing to etching. In addition, it is inexpensive and economically advantageous. In addition, from the perspective of environmental impact, sulfuric acid, which is an inorganic acid containing no phosphorus or nitrogen, is preferable. Phosphoric acid can form a phosphorus-based film on the surface of the metal material in addition to promoting etching of the surface of the metal material. Thereby, since the exposure of aluminum is suppressed, brown spots generated by the reaction between the rinsing water and aluminum can be suppressed. In addition, the chemical conversion treatment step after cleaning the metal material with the cleaning solution can be omitted. In addition to the above, since phosphoric acid is widely applied industrially and is also used as a food additive, it can be preferably used when the metal material is used for food-related applications such as beverage cans.

[0019] In the present disclosure, the concept of phosphoric acid includes acidic substances other than phosphates that ionize in the cleaning solution to generate phosphate ions (PO4 3- ). Examples of the above substances include phosphonic acid, pyrophosphoric acid, metaphosphoric acid, etc. The above phosphoric acid and substances that generate phosphate ions may be used alone or in combination of two or more.

[0020] The content (mass concentration) of the inorganic acid in the cleaning solution is 0.01 g / L or more and 25 g / L or less. When the content of the inorganic acid is less than 0.01 g / L, the etching rate decreases, and the removal effect of aluminum oxide and smut becomes insufficient. On the other hand, when the content of the inorganic acid exceeds 25 g / L, no further effect on etching is recognized, which is economically disadvantageous. The content of the inorganic acid is preferably 10 g / L or more. Note that the content of the inorganic acid defined in this application does not include inorganic acids derived from salts (including salts of trivalent iron ions).

[0021] (Trivalent iron ion) Trivalent iron ion (Fe 3+ ) has a function as an etching accelerator. The etching reaction of aluminum-based metals in an acidic cleaning solution consists of an anodic reaction in which aluminum becomes aluminum ions (Al 3+ ) and a cathodic reaction in which H + in the acidic cleaning solution is reduced to 1 / 2H2. Therefore, when trivalent iron ions (Fe 3+ ), which are oxidized metal ions, are present in the acidic cleaning solution, an anodic reaction in which this Fe 3+ is reduced to Fe 2+ occurs simultaneously with the reduction of the above H + , and the etching reaction of aluminum is promoted.

[0022] The source of trivalent iron ions is not particularly limited as long as it can ionize in the cleaning solution to generate trivalent iron ions. The source of trivalent iron ions is preferably a water-soluble salt such as a sulfate or a nitrate. For example, ferric sulfate or ferric nitrate can be used as the above source. As the source of trivalent iron ions, one substance may be used, or two or more substances may be used in combination.

[0023] The content (mass concentration) of trivalent iron ions in the cleaning solution is between 0.05 g / L and 4.0 g / L. If the concentration of trivalent iron ions is less than 0.05 g / L, the etching rate decreases, and the smut removal effect becomes insufficient. On the other hand, if the concentration of trivalent iron ions exceeds 4.0 g / L, no further effect on etching is observed, making it economically disadvantageous. It is preferable that the content of trivalent iron ions be 0.1 g / L or more.

[0024] (Surfactants) The cleaning solution according to this embodiment includes, as surfactants: Surfactant A: a polyoxyalkylene alkyl ether with a cloud point of 80°C or higher; Surfactant B: a polyoxyalkylene alkyl ether with a cloud point of 50°C or higher and 60°C or lower; and Surfactant C: a polyoxyalkylene alkyl ether with a cloud point of 40°C or lower. In this specification, the term "polyoxyalkylene" means that the compound contains a structure in which one or more oxyalkylene groups (e.g., oxyethylene group: -CH2CH2O-, oxypropylene group: -CH2CH2CH2O-, etc.) having any number of carbon atoms are polymerized or copolymerized. Surfactant A has excellent cleaning properties but significantly poor foaming properties. Surfactant B does not have a major problem with foaming properties, but its cleaning properties are inferior to those of surfactant A. By combining these two surfactants with surfactant C, which suppresses foaming, three surfactants having different cloud point ranges, it is possible to achieve both desirable cleaning properties and the effect of suppressing foaming. Furthermore, since the theoretical cloud point can be controlled, for example, the processing temperature can be set to a lower temperature near the theoretical cloud point. The theoretical cloud point can be calculated from the content ratio and cloud point of each surfactant.

[0025] In this specification, "cloud point" refers to the cloud point defined in JIS K 3211:1990. The cloud point is a physical property specific to aqueous solutions of surfactants to which alkylene oxide is attached as a hydrophilic group. At temperatures above the cloud point, the aqueous solution undergoes phase separation and sufficient cleaning power cannot be obtained; therefore, cleaning treatment at temperatures around the cloud point is generally considered to have the highest cleaning effect. The cloud point can vary depending on the structure of the surfactant (type and ratio of alkylene oxide, length of alkyl group, presence or absence of branched structure, etc.).

[0026] Surfactants A and B, when included in the cleaning solution, improve the removal (cleaning) of oils such as lubricating oil. Surfactant C, when included in the cleaning solution, has the effect of suppressing foaming. The above surfactants suppress the suspension of removed oils such as lubricating oil in the cleaning solution. If oils such as lubricating oil are suspended in the cleaning solution, there is a risk of re-adsorption to the surface of aluminum-based metal materials, but the above surfactants can suppress re-adsorption. These surfactants are not particularly limited as long as they are within the respective cloud point ranges, and commercially available products can be used.

[0027] The surfactant content (mass concentration) in the cleaning solution is between 0.1 g / L and 10 g / L. The above content refers to the total content of surfactants A, B, and C. If the surfactant concentration is less than 0.1 g / L, the cleaning performance, especially the degreasing performance, will decrease. On the other hand, if the surfactant concentration exceeds 10 g / L, foaming will occur in the cleaning solution, making the cleaning process difficult and placing a burden on wastewater treatment. Preferably, the surfactant content is between 0.2 g / L and 5 g / L.

[0028] The surfactant B is preferably a poly(oxyethylene oxypropylene) alkyl ether. This makes it easier to obtain desirable cleaning properties.

[0029] In the cleaning solution, the ratio (MA:MB) of the mass concentration (MA) of surfactant A to the mass concentration (MB) of surfactant B is preferably 5:1 to 1:6. Thereby, it is possible to achieve both suppression of the amount of foam while maintaining preferable detergency.

[0030] In the cleaning solution, the ratio (MC / (MA + MB)) of the mass (MC) of surfactant C to the total (MA + MB) of the mass (MA) of surfactant A and the mass (MB) of surfactant B is preferably 1 / 3 or more. The above ratio (MC / (MA + MB)) is preferably 1 / 3 or more and 1 or less. When the ratio of MC is small, foaming occurs in the cleaning solution and the cleaning process becomes difficult, and when it is large, the detergency decreases.

[0031] (Other components) In the cleaning solution according to the present embodiment, other components may be arbitrarily blended in addition to the above. For example, water which is a solvent for each component, surfactants other than the above, oxidizing agents, organic sulfonic acids, etc. can be mentioned.

[0032] As surfactants other than the above, within a range not impairing the effects of the present disclosure, known surfactants of nonionic, cationic, anionic, and zwitterionic types can be further added.

[0033] The oxidizing agent oxidizes divalent iron ions to trivalent iron ions. As the etching reaction of the metal material by the cleaning solution proceeds, the concentration of divalent iron ions (Fe 2+ ) increases. Thereby, the oxidation-reduction potential (hereinafter referred to as ORP: oxidation-reduction potential) decreases (also referred to as aging of the cleaning solution), and the effect of promoting etching on the aluminum surface disappears. Therefore, it is preferable to add an oxidizing agent for controlling ORP to the cleaning solution. The oxidizing agent may be contained in the cleaning solution in advance, or may be added to the cleaning solution at any time as the cleaning process (progress of the etching reaction) proceeds. The oxidizing agent is not particularly limited, but for example, hydrogen peroxide (H2O2), persulfate (for example, NaS2O8 2-Examples include ozone (O3), cerium compounds (e.g., cerium ammonium sulfate: (NH4)4Ce(SO4)4), and nitrites (e.g., NaNO2, KNO2).

[0034] Organic sulfonic acids can be added to cleaning solutions primarily to ensure sufficient etching effect even under low-temperature conditions. Organic sulfonic acids have a structure represented by the following formula (1). R-SO3H ···(1) (In formula (1), R represents a methyl group or a substituted alkyl group having 1 to 9 carbon atoms and at least one hydroxyl group.)

[0035] The substituted alkyl group in formula (1) above is not limited to a straight chain, but may also be a branched chain. Specific examples of the above organic sulfonic acid include HSO3-CH3, as well as HSO3-CH2OH, HSO3-CH2CH2OH, HSO3-CH2CH2CH2OH, HSO3-CH2CH(OH)CH2OH, etc. Organic sulfonic acid may be used alone or in combination of two or more types.

[0036] The organic sulfonic acid content is preferably between 0.01 g / L and 0.2 g / L. If the content is less than 0.01 g / L, the effect will be insufficient, and if it exceeds 0.2 g / L, no further effect will be observed, making it economically disadvantageous.

[0037] [Aluminum-based metal materials] The aluminum-based metal material to be treated with the cleaning solution according to this embodiment is not particularly limited as long as it mainly contains aluminum, and examples include aluminum or aluminum alloys. The aluminum-based metal material mainly containing aluminum may, for example, contain 50% by mass or more of aluminum. The aluminum-based metal material is preferably used for aluminum cans such as beverage cans manufactured by a drawing process called DI processing.

[0038] <Cleaning method for aluminum-based metal materials> The cleaning method for aluminum-based metal materials according to this embodiment includes a cleaning step of bringing the cleaning solution described above to a predetermined liquid temperature and bringing it into contact with the surface of the metal material for cleaning. While the cleaning step is included, other steps may be optionally included. For example, a water rinsing step or a drying step may be included.

[0039] The method for bringing the cleaning solution into contact with the metal material is not particularly limited, and any method known in the art can be appropriately selected. Examples include spraying and immersion methods. In particular, since the cleaning solution according to this embodiment can effectively suppress foaming, efficient cleaning can be performed even when the spraying method is applied.

[0040] In this embodiment, the liquid temperature of the cleaning solution in the cleaning process is preferably 40°C to 75°C. More preferably, the liquid temperature of the cleaning solution is 55°C to 70°C. This reduces the cost required for the cleaning process.

[0041] The contact time with the metal material in the cleaning solution is not particularly limited, as long as sufficient etching is possible and, if the cleaning solution contains phosphoric acid, a uniform phosphorus-based film can be formed on the surface of the metal material. The above time can be set appropriately according to the processing temperature. For example, when using a cleaning solution with a liquid temperature of 40°C to 70°C, the contact time is preferably 25 seconds to 60 seconds. [Examples]

[0042] The contents of this disclosure will be described in more detail below based on the following examples. The contents of this disclosure are not limited to the following examples.

[0043] [Preparation of cleaning solution] The cleaning solutions for each example and comparative example were prepared to have the component types and concentrations listed in Table 1 below. For the trivalent iron ions, ferric sulfate (manufactured by Jujo Synthetic Chemical Research Institute, trade name: Ferric Sulfate Solution) was used. In addition to the components listed in Table 1, each cleaning solution contained water as a solvent. The concentrations (g / L) listed in Table 1 refer to mass concentrations.

[0044] [Table 1]

[0045] Details of the abbreviations listed in Table 1 are shown below. The cloud points of surfactants A, B, and C were measured by the following method: A 1% by mass aqueous solution of the surfactant was slowly heated while gently stirring, and the temperature at which the clear solution became cloudy was measured and defined as the cloud point.

[0046] (Surfactant A) A1: Emulgen 120 (manufactured by Kao Corporation, polyoxyethylene alkyl ether, cloud point 98°C) A2: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene alkyl ether, cloud point 83°C) A3: Adekatol LA-975 (manufactured by ADEKA Corporation, polyoxyethylene alkyl ether, cloud point 80°C) A4: Brownon EL1512P (manufactured by Aoki Oil & Fat Industry Co., Ltd., polyoxyethylene alkyl ether, cloud point 86℃) A5: Brownon EL1521 (manufactured by Aoki Oil & Fat Industry Co., Ltd., polyoxyethylene alkyl ether, cloud point 80°C or higher)

[0047] (Surfactant B) B1: Emulgen LS-110 (manufactured by Kao Corporation, poly(oxyethylene oxypropylene) alkyl ether, cloud point 55℃) B2: Adekanol BO-901 (manufactured by ADEKA Corporation, poly(oxyethylene oxypropylene) alkyl ether, cloud point 54℃) B3: Neugen TDX-80D (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., poly(oxyethylene oxypropylene) alkyl ether, cloud point 56℃) B4: FineSurf TDE-1055 (manufactured by Aoki Oil & Fat Industry Co., Ltd., poly(oxyethylene oxypropylene) alkyl ether, cloud point 55℃) B5: Brownon EL1507 (manufactured by Aoki Oil & Fat Industry Co., Ltd., polyoxyethylene lauryl ether, cloud point 57℃)

[0048] (Surfactant C) C1: Emulgen 707 (manufactured by Kao Corporation, polyoxyethylene alkyl ether, cloud point 33°C) C2: Neugen LF-40X (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., poly(oxyethylene oxypropylene) alkyl ether, cloud point 20℃) C3: Neugen LF-41X (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., poly(oxyethylene oxypropylene) alkyl ether, cloud point 28℃)

[0049] [Effervescence Test] The cleaning solutions for each example and comparative example were sprayed continuously for 5 minutes at the processing temperature shown in Table 2 and a spray pressure of 0.34 MPa onto aluminum cans manufactured by DI processing, which are aluminum-based metal materials. After spraying onto the cans, the foam height (cm) from the liquid surface of the cleaning solution that accumulated in a bathtub placed at the bottom was evaluated according to the following evaluation criteria, with a rating of 3 or higher being considered a pass. The results are shown in Table 2.

[0050] (Evaluation Criteria) 5.0cm or more, less than 2cm 4.2cm to less than 4cm 3-4cm to less than 6cm 2.6cm to less than 8cm 1.8cm or more

[0051] [Cleaning process] Aluminum cans manufactured by DI processing, which are aluminum-based metal materials, were cleaned by spraying using the cleaning solutions described in each example and comparative example. The cleaning temperature and treatment time are as shown in Table 2. The cleaning temperatures in Table 2 were set to be near the theoretical cloud point, determined from the content ratio and cloud point of each surfactant.

[0052] [Exterior evaluation] After cleaning with the cleaning solution described in each example and comparative example, the aluminum cans were dried, and their whiteness was visually evaluated according to the following criteria. A good result was given when degreasing and desmudging were complete and the cans had a sufficiently etched white appearance, and the degree of whitening was evaluated accordingly. A rating of 4 or higher was considered acceptable. The results are shown in Table 2.

[0053] (Evaluation Criteria) 5. The entire surface is white. 4. It has many white areas, with some light gray areas. 3. It is light gray overall. 2. There are many light gray areas, and some parts are gray. 1. The entire surface is gray.

[0054] [Water wettability] After cleaning each aluminum can with the cleaning solution described in the examples and comparative examples, the can was further spray-washed. Immediately afterward, the container was shaken three times to remove excess water, and the container was left upright for 30 seconds. The water-covered area (%) of the outer surface of the container was visually measured. 100% was considered a pass. The results are shown in Table 2.

[0055] [Table 2]

[0056] The above appearance evaluation indicates the evaluation of degreasing and desmutting properties, i.e., cleaning performance. The above water wettability also indicates the evaluation of degreasing properties, i.e., cleaning performance. From the results shown in Table 2, it is clear that the cleaning solutions in each example can achieve both desirable cleaning performance and the effect of suppressing foaming compared to the cleaning solutions in the comparative examples.

Claims

1. At least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid, nitrite, and phosphoric acid is added in a concentration of 0.01 g / L to 25 g / L. The concentration of trivalent iron ions is 0.05 g / L or more and 4.0 g / L or less. It contains a surfactant in a concentration of 0.1 g / L or more and 10 g / L or less. The surfactant is Surfactant A: A polyoxyalkylene alkyl ether having a cloud point of 80°C or higher, Surfactant B: A polyoxyalkylene alkyl ether having a cloud point of 50°C or higher and 60°C or lower, Surfactant C: Contains a polyoxyalkylene alkyl ether having a cloud point of 40°C or lower. Acidic cleaning solution for aluminum-based metal materials.

2. The acidic cleaning solution for aluminum-based metal materials according to claim 1, wherein the surfactant B is poly(oxyethyleneoxypropylene) alkyl ether.

3. The acidic cleaning solution for aluminum-based metal materials according to claim 1, wherein the ratio (MA:MB) of the mass concentration (MA) of surfactant A to the mass concentration (MB) of surfactant B in the acidic cleaning solution for aluminum-based metal materials is 5:1 to 1:

6.

4. The acidic cleaning solution for aluminum-based metal materials according to claim 1, wherein the ratio of the mass of surfactant C (MC) to the sum of the mass of surfactant A (MA) and the mass of surfactant B (MB) (MA + MB) in the acidic cleaning solution for aluminum-based metal materials (MC / (MA + MB)) is 1 / 3 or more.

5. The acidic cleaning solution for aluminum-based metal materials according to claim 1, wherein the ratio of the mass of surfactant C (MC) to the sum of the mass of surfactant A (MA) and the mass of surfactant B (MB) (MA + MB) in the acidic cleaning solution for aluminum-based metal materials (MC / (MA + MB)) is 1 / 3 or more and 1 or less.

6. The acidic cleaning solution for aluminum-based metal materials according to claim 1, wherein the inorganic acid contains the phosphoric acid, and the concentration ratio (phosphoric acid:trivalent iron ions) of the mass concentration (g / L) of the phosphoric acid to the mass concentration (g / L) of the trivalent iron ions in the acidic cleaning solution for aluminum-based metal materials is 35:1 to 180:1.

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