JPH08225970A - Alkaline liquid degreasing agent for aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE: To obtain the liquid degreasing agent which has excellent degreasing power and contains no phosphorus by using an alkali metal silicate that functions as an inorganic builder, a specific nonionic surfactant and water as the major components of the agent. CONSTITUTION: This degreasing agent contains as the major components, 1.5 to 5.0wt.% (expressed in terms of SiO2 ) of an alkali metal silicate as an inorganic builder, 10 to 25wt.% of at least one compound selected from trialkylamine oxide or dihydroxyethylmonoalkylamine oxide represented by the formula as a surfactant and water. In the formula, R1 is a C10 to C22 alkyl group and R2 is a methyl, ethyl or hydroxyethyl group. The agent is applied for cleaning the surface of Al or an Al alloy and shows durable excellent degreasing power even at the time of continuously using it for removing a large amount of oil and also, contains no phosphorus that may cause eutrophication of river or lake water. Further, the COD of waste water from a degreasing process, that may become a problem at the time of treating the waste water, can be controlled at or below a low value by using this agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an alkaline liquid degreasing agent for aluminum and aluminum alloys. More specifically, the present invention is sufficient for removing oil and dirt adhering to the surface of aluminum and aluminum alloys, and is three times as much as the degreasing agent pure content (total weight of inorganic builder and surfactant). Alkaline liquid degreasing with low COD (chemical oxygen demand), which has good degreasing properties even when mixed with a large amount of oil, does not contain phosphorus that causes eutrophication of rivers and lakes, and has good wastewater treatment. It is related to agents.

[0002]

2. Description of the Related Art Generally, a degreasing agent for aluminum and aluminum alloys contains an inorganic builder having a phosphate or a condensed phosphate as a main component from the viewpoint of detergency, and further contains a chelating agent and a surfactant. There is. Further, as a phosphorus-free alkaline degreasing agent containing no phosphate or condensed phosphate, JP-A-6-116768 discloses (A) 0.0.
5 to 0.30% by weight (SiO ₂ conversion) of silicate, and
An inorganic builder consisting of 4 to 3.0% by weight of at least one selected from sodium hydroxide, sodium carbonate and sodium hydrogen carbonate, and (B) 0.01 to 0.5% by weight of ethylenediaminetetraacetic acid salt and nitrilotri At least one selected from acetate and 0.1 to 0.5% by weight of polyacrylic acid salt, cyclopentane tetracarboxylic acid salt, polycarboxylic acid salt, hydroxycarboxylic acid salt and urethanized polyvinyl alcohol. An organic builder comprising at least one kind, and (C) 0.2-
A phosphorus-free alkaline degreaser for low temperature metal cleaning is shown containing 0.6% by weight of a surfactant. It has been disclosed that the phosphorus-free alkaline degreasing agent exhibits an excellent cleaning effect on the metal surface even when continuously used at a low temperature of 35 to 45 ° C. and can impart a surface having good chemical conversion treatment property to the metal material. However, in order to impart excellent detergency, it was necessary to use a surfactant having a high COD.

Further, in recent years, with increasing awareness of environmental protection on a global scale, regulations regarding waste water from factories and the like to rivers, lakes and marshes in the fields of chemistry, electrical machinery, machinery and the like have become strict. Therefore, degreasing agents for aluminum, such as dephosphorization and low COD, have been required to suppress eutrophication of rivers and lakes. Further, in order to reduce the cost in the processing line, there is a demand for a degreasing agent having a long life, which minimizes the renewal of the degreasing solution, that is, maintains good detergency even when a large amount of oil is mixed. There is. From the viewpoint of workability, liquid degreasing agents are preferable to powder degreasing agents.

However, up to now, while satisfying the above-mentioned requirements, in particular, oil content resistance and low COD, and
At present, liquid degreasing agents for aluminum and aluminum alloys which satisfy excellent cleaning performance have not yet been obtained.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the above-mentioned prior art, and is applied to the cleaning of aluminum and aluminum alloy surfaces and continuously used in large amounts. Oil content, eg pure degreaser (total weight of inorganic builder and nonionic surfactant)
For aluminum and aluminum alloys, which retains excellent degreasing ability even when mixed with 3 times the amount of oil, does not contain phosphorus, and at the same time can reduce COD value, which is a problem during wastewater treatment. It is intended to provide an alkaline liquid degreasing agent.

[0006]

Means for Solving the Problems As a result of intensive studies on the means for solving the above problems, the present inventors have used a specific amount of an alkali metal silicate as an inorganic builder, and have a surfactant having a specific structure. It has been newly found that the above problems can be solved by using an alkaline liquid degreasing agent containing water and water, and the present invention has been completed.

That is, the present invention provides (A) an inorganic builder
Alkali metal silicate as 1.5 to 5.0% by weight
(SiO₂(Conversion), (B) as nonionic surfactant
A trialkylamine oxide represented by the following formula (1) or
Selected from dihydroxyethyl monoalkylamine oxide
10-25% by weight of at least one type (However, R in the above formula₁Is an alkyl having 10 to 22 carbon atoms
Represents a radical, R₂Is methyl, ethyl or hydroxy
(Represents an ethyl group) and (C) water as a main component
Aluminum and aluminum alloys characterized by
An alkaline liquid degreaser for use.

The present invention will be described in detail below. The aluminum and aluminum alloys targeted by the present invention are metal materials containing aluminum and aluminum alloys as main components, such as aluminum plates, aluminum alloy plates and aluminum die cast materials.

The alkali metal silicate used as the inorganic builder of the present invention is blended for the purpose of improving degreasing property, and its action is to prevent redeposition of stains on the article to be cleaned and to remove acidic substances. For example, saponification to make the oily substance easily soluble. As the silicate builder, for example, commercially available sodium metasilicate, sodium orthosilicate, etc., as well as potassium salts and lithium salts thereof can be used. Commercially available sodium silicate is in the form of an anhydrous salt or various hydrated salts, but its compounding concentration is defined by the amount converted to SiO _{2 in} sodium silicate, and the appropriate range of the silicate is alkaline liquid degreasing in terms of SiO _2. 1.5 to 5.0% by weight, more preferably 2.0, based on the total weight of the agent.
~ 3.0 wt%. When this concentration is less than 1.5% by weight, the degreasing property of the obtained alkaline liquid degreasing agent becomes insufficient, and when it exceeds 5.0% by weight, the degreasing property can be sufficiently secured, but the effect of increasing the concentration is It is saturated and economically wasteful.

Next, the nonionic surfactant used in the present invention is at least one selected from trialkylamine oxides and dihydroxyethylmonoalkylamine oxides represented by the following general formula (1). (However, R ₁ in the above formula represents an alkyl group having 10 to 22 carbon atoms, and R ₂ represents a methyl group, an ethyl group or a hydroxyethyl group).

The number of carbon atoms of R _{1 in} the above formula (1) is 10
If it is less than or exceeds 22, the degreasing property tends to be poor, such being undesirable. Further, if the number of carbon atoms exceeds 22, COD tends to be high. It should be noted that R ₂ is preferably a methyl group, an ethyl group or a hydroxyethyl group, and other than that, a low COD and a good degreasing property cannot be obtained.

The nonionic surfactant having the above structure has a significantly lower COD value than that of a general type of nonionic surfactant such as polyoxyethylene nonylphenol ether. It has little impact on the environment. Examples of the amine oxide that can be used in the present invention include dimethylcaproylamine oxide, dimethyllaurylamine oxide, dimethylmyristylamine oxide, dimethylpalmitylamine oxide, dimethylstearylamine oxide, dimethylbehenylamine oxide, diethyllaurylamine oxide and diethyl. Stearylamine oxide, dihydroxyethyllaurylamine oxide, dihydroxyethylmyristylamine oxide and the like can be mentioned. In addition, other than the above, as long as R has 10 to 22 carbon atoms, those having a branched structure can also be used. Among these nonionic surfactants, dimethyllaurylamine oxide having 12 carbon atoms of R ₁ ,
Particular preference is given to using diethyllaurylamine oxide, dihydroxyethyllaurylamine oxide.

In the present invention, the proper concentration range of these nonionic surfactants is 10 to 10% of the total amount of the surfactant.
It is 25% by weight. It is more preferably 15 to 20% by weight. If this concentration is less than 10% by weight, the degreasing property is poor, and especially when oil is mixed, the degreasing property is deteriorated. on the other hand,
When it exceeds 25% by weight, the degreasing property is good even when oil is mixed, but it is not preferable because it increases the COD value of the degreasing agent. Further, if it is added in an amount of more than 25% by weight, the storage stability of the degreasing agent becomes poor, which is not preferable.

The reason why the degreasing property is good when a specific nonionic surfactant used in the present invention is mixed with a large amount of oil is not clear, but it is considered as follows. That is, the nonionic surfactant of the present invention is
Although it is non-ionic in the degreasing liquid, it has a strongly polarized portion in the molecule, so in the micelle state surrounding oil, the surface of the micelle is slightly charged with anions. for that reason,
It is considered that the oil particles are prevented from redepositing on the surface of the object to be treated, which is charged with anions, and exhibit good degreasing properties.

An antifoaming agent may be added to the alkaline liquid degreasing agent of the present invention in order to suppress the adverse effects of foaming during washing work. This defoaming agent can be appropriately selected and used from those usually used.

The alkaline liquid degreasing agent of the present invention is
It is preferable to use a solution that is appropriately diluted 10 to 100 times with water according to the surface condition of the object to be cleaned (amount of oil, dust, etc.), and more preferably 20 to 50 times. .

The treatment temperature, treatment time and treatment method of the alkaline liquid degreasing agent for aluminum and aluminum alloys of the present invention are not particularly limited because the conditions vary depending on the surface condition (oil, dust adhesion condition) of the object to be cleaned. However, due to foaming, the temperature is usually 60 to 80 ° C,
Immersion treatment is performed for 20 to 120 seconds.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. Examples 1 to 8 and Comparative Examples 1 to 5 [Preparation of sample alkaline liquid degreasing agent] Inorganic builders and nonionics having the compositions shown in Table 1 for each of Examples 1 to 8 and Comparative Examples 1 to 5 The alkaline liquid degreasing agent was prepared by mixing the surface active agent and water. The prepared degreasing agent was diluted with water to a concentration of 50 g / 1 to obtain a test alkaline liquid degreasing agent.

[Sample Material] (a) Aluminum alloy (JIS A 5052 material): Dimension 50 mm × 100 mm Plate thickness 1.0 mm (b) Fin material (JIS A 3000 series): Dimension 50 mm × 100 mm Plate thickness 0.3 mm

[Method of measuring COD value] The COD value (ppm) of the above-mentioned test alkaline liquid degreasing solution is determined according to JIS-K-010.
It measured according to the method of 2-17.

[Degreasing Test Method] The above-mentioned test material (a),
After the surface of (b) was washed with 1,1,1-trichloroethane by steam, press oil (G-634B, Nippon Machine Oil Co., Ltd.)
Machine oil (No. 1 spindle oil, Nippon Oil Co., Ltd.)
A mixture of 1: 1 by volume) was applied by a roll coater to a coating amount of about 2 g / m ^2, and
It was left for a day and used as a test material. In the degreasing test, the above mixed oil was added to the test degreasing liquid at 10,000 ppm, 20,
000ppm and 50,000ppm added,
If not added, each degreaser should be 60 ± 2 ℃
The test material (a) and (b) are soaked for 60 seconds so that they do not contact each other, and then spray-washed for 30 seconds to make the test material vertical.
The sample was left to stand indoors for seconds, and immediately the water-wetted area (%) of the two test materials was measured. The test results are shown in Table 2.

The following can be said from Examples 1 to 8 and Comparative Examples 1 to 5. Examples 1 to 8 using the alkaline liquid degreasing agent of the present invention
Has a low COD value and excellent degreasing property. Comparative Example 1 in which the addition amount of the inorganic builder (SiO ₂ conversion amount) is small, and Comparative Examples 2 and 3 in which the addition amount of the nonionic surfactant of the present invention is small, have a degreasing property even when oil is not mixed. It was not sufficient, and the decrease in degreasing property when oil was mixed was remarkable. In addition, Comparative Example 4 using a nonionic surfactant other than the present invention and Comparative Example 5 containing both an inorganic builder other than the present invention and a nonionic surfactant are degreased when oil is not mixed. Is almost the same as the product of the present invention, but the oil content is 2
The degreasing property was drastically lowered when the amount was over 10,000 ppm. Furthermore, since the COD value is quite high, it seems that wastewater treatment is difficult.

[0023]

As described above, when the alkaline liquid degreasing agent of the present invention is applied for degreasing aluminum and aluminum alloy surfaces, it is continuously used and the degreasing agent pure component (inorganic builder and surfactant is used). (3) Total amount of oil), excellent degreasing ability can be maintained even when oil content is mixed, liquid life can be extended, phosphorus is not contained, and COD value, which is a problem during wastewater treatment, can be kept low. Because it is also possible, it has great industrial value.

[0024]

[Table 1]

[0025]

[Table 2]

Claims (1)

[Claims] 1. The following components: (A) an alkali metal silicate as an inorganic builder;
5 to 5.0% by weight (SiO₂Conversion), (B) non-ionic
As a surfactant, a trialkyl group represented by the following formula (1)
Minoxide or dihydroxyethyl monoalkylami
At least one selected from the oxides of 10 to 2
5% by weight, (However, R in the above formula₁Is an alkyl having 10 to 22 carbon atoms
Represents a radical, R₂Is methyl, ethyl or hydroxy
(Represents an ethyl group) and (C) water as a main component
Aluminum and aluminum alloys characterized by
Alkaline liquid degreaser for use.