JPS5819717B2 - Road antifreeze agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a road surface antifreeze agent, and particularly to a road surface antifreeze agent that is less corrosive to metals.

In recent years, road antifreeze agents using ammonium sulfate, calcium chloride, magnesium chloride, urea, etc. have been proposed.

However, these ammonium sulfate, calcium chloride, magnesium chloride, urea, etc. (hereinafter, these may be collectively referred to as "metal corrosive compounds").

) has the disadvantage that it has a significant corrosive effect on metals, especially carbon steel, and has a significant corrosive effect on metal parts such as automobiles, road guardrails, and signs.

As a result of various studies conducted by the present inventors on the prevention of metal corrosion caused by the metal-corrosive compounds described above, the inventors have found that, in particular, ammonium sulfate and urea are mixed in a specific ratio, and the mixture is treated with ammonium salts of phosphoric acid, alkali metals, etc. salts,
alkaline earth metal salts and mixtures of two or more thereof;
In particular, we have found that by adding an appropriate amount of certain phosphates, it is possible to significantly reduce the corrosivity and obtain a road surface antifreeze agent with antifreeze effect, and have thus arrived at the present invention. It is something.

The present invention provides a method for adding at least one phosphate selected from ammonium phosphate, sodium phosphate, and sodium tripolyphosphate to a mixture consisting of 80 to 50% by weight of ammonium sulfate and 20 to 50% by weight of urea. It is a road surface antifreeze agent added in a proportion of 0.1 to 20% by weight.

Phosphates which are added to the mixture of ammonium sulfate and urea to obtain road antifreeze agents include ammonium phosphates, alkali metal phosphates and alkaline earth metal phosphates, such as ammonium phosphate, niummonium phosphate, urea phosphate, etc. Sodium, disodium phosphate, potassium phosphate, dipotassium phosphate, calcium hydrogen phosphate and magnesium hydrogen phosphate, etc., as well as sodium, potassium and ammonium salts of polyphosphoric acids such as pyrophosphoric acid, triphosphoric acid, tripolyphosphoric acid and tetrametaphosphoric acid. However, in the present invention, ammonium phosphate, sodium phosphate, and sodium tripolyphosphate are selected and used because they have particularly excellent effects.

These phosphates can be used alone or in an appropriate combination of two or more.

It may also be used in combination with known metal corrosion inhibitors.

The ratio of ammonium sulfate and urea in the road antifreeze agent of the present invention is 80 to 50% by weight of ammonium sulfate and 20 to 50% by weight of urea (see each example).

If the proportion of ammonium sulfate increases beyond this range, the corrosiveness to metals will increase, and if the proportion of urea increases, the antifreeze effect will decrease and the corrosivity to metals will increase (see Comparative Examples 1 and 2). ).

The proportion of phosphate is 0.1 to 2.0% by weight, preferably 0.0% by weight, based on the ammonium sulfate and urea mixture.
It is 5 to 8% by weight.

If the proportion of phosphate used is too small, a sufficient corrosion-proofing effect cannot be obtained, and if it is increased beyond the above range, even if some improvement in the corrosion-proofing effect is recognized, the degree of improvement is small; In fact, it is economically disadvantageous.

The addition of phosphate to the ammonium sulfate and urea mixture can be carried out in various ways.

For example, a method of uniformly mixing both powders and granules by tri-blending, a method of melting both or one of them and then mixing them, or a method of dissolving both or one of them in water and then mixing (a method of drying after mixing) include.

) etc. In addition, when adding and mixing the ammonium sulfate and urea mixture and the phosphate to obtain the road antifreeze agent of the present invention, other third components are added to one or both of them in advance, and then both are added. There is no problem even if they are mixed, or it is also possible to add another third component after mixing the two.

For example, using a compound that has good water solubility at low temperatures and lowers the freezing point of water as the third component, preferably a compound that is less corrosive to metals and generates heat when dissolved,
These can be appropriately mixed in various manners as described above.

The standard for the corrosion rate (rate of weight loss) for cold-rolled steel sheets that is normally accepted as a road surface antifreeze agent is 7 g/m,"·day, when tested using the test method described in Example 1. , for example, urea and ammonium sulfate in a weight ratio of 1=
The corrosion rate of a 3% aqueous solution mixed at a ratio of 1 is 21
Reaches 97m''.

However, when the above-mentioned various phosphates are added to this aqueous solution in a range of 0.1 to 20% by weight based on the metal corrosive compound, the corrosivity is significantly reduced, and the corrosion rate can be easily reduced to the above-mentioned standard corrosion rate. It is possible to reduce the amount to less than 7 g/m'/day.

Next, the present invention will be explained in more detail with reference to examples, but these examples are not intended to limit the present invention in any way.

In addition, the parts described in Examples represent parts by weight.

Example 1 15 parts of ammonium sulfate, 15 parts of urea and 0.3 parts of ammonium phosphate were mixed and molded under a pressure of 1 using a pressure molding machine.
70 kg, / crj, thickness 1 mm 1 width 100 mm
A road antifreeze agent was produced by molding the mixture into a sheet and crushing it into flakes using a hammer crusher.

When 100 g of this road surface antifreeze was mixed with 200 g of crushed ice, the lowest temperature reached was -17°C.

Apply 30 g of this road surface antifreeze to a road with a road surface temperature of -5℃.
When the material was evenly spread at a ratio of 1/m'', no freezing was observed even when there was snowfall on ■θ steel.

In addition, the following metal corrosion test was conducted on this road surface antifreeze agent.

That is, a metal test piece (JIS G3113 Class 1, Nippon Steel Corporation 5APH32, size 0.8 x 2.5 x 50
mm) was polished, sequentially washed with warm anhydrous solvent naphtha and warm methanol, dried, and then weighed.

Next, 3 obtained by dissolving the above road antifreeze agent in water.
Using a wt% aqueous solution as the test liquid, the above test piece was subjected to the dry-wet alternating test method (the test piece was immersed in the test liquid at 40°C for 1 minute, and then left in the air at 30°C for 2 minutes). A corrosion test was conducted for 5 days using a test method of sequentially and continuously repeated tests.

After the first corrosion test, the surface of the test piece was washed with water while being rubbed with a brush, washed with acetone, dried, and weighed.

The corrosion rate was calculated from the weight of the test piece before and after the first corrosion test, and was found to be 2 El/m·day.

For comparison, a 3% by weight aqueous solution of a road surface antifreeze prepared by mixing and molding 15 parts of ammonium sulfate and 15 parts of urea and pulverizing was used, except that ammonium phosphate was not used. When a similar corrosion test was conducted, the corrosion rate was 21 g/'m''·day.

Examples 2 to 4 Road antifreeze agents were produced by mixing the components in the composition and proportions shown below, and otherwise following the method described in Example 1.

When the metal corrosion test described in Example 1 was conducted using the 3% by weight aqueous solution of each of the obtained road surface antifreezes, the corrosion rates were as shown in the table below.

Comparative Examples 1-2 A road surface antifreeze agent was produced by mixing each component in the composition and proportions shown in the table below, and otherwise following the method described in Example 1.

1. When the metal corrosion test described in Example 1 was conducted using the obtained 3% by weight aqueous solution of each road antifreeze agent, the corrosion rate was 5 as shown in the table below.

As is clear from the comparison between Examples 2 to 4 and Comparative Examples 1 to 2, the antifreeze of the example in which phosphate was added to a mixture of ammonium sulfate and urea was different from the antifreeze in which phosphate was added to ammonium sulfate or urea. It is significantly less corrosive than .

Claims (1)

[Claims] 1 Ammonium sulfate 80-50% by weight and urea 20-50%
A road surface obtained by adding at least one phosphate selected from ammonium phosphate, sodium phosphate, and sodium tripolyphosphate to a mixture consisting of 50% by weight in an amount of 0.1 to 20% by weight relative to the above mixture. Antifreeze.