JPS6041714B2 - Co-low polymer rust inhibitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rust preventive agent comprising a polymer having a repeating unit consisting of a maleic acid derivative and an alkyl vinyl ether and having an extremely low degree of polymerization and a narrow distribution.

Conventionally, various rust preventives have been proposed, but
There are few low-toxicity compounds that can be used over a wide range of applications, and there are almost no known ones that can simultaneously prevent the rust of many types of metals. For example, this type of rust inhibitor includes petroleum sulfonates, sorbitan monooleate, metal soaps, etc. as oil-soluble ones, and inorganic as chromates, phosphates, nitrites, etc. as water-soluble ones. Salt, water/oil soluble ones such as ethanolamine, benzotriazole,
There are alkyl phosphate surfactants, long-chain quaternary ammonium halides, and higher amine salts, but these have low solubility in specific solvents or are only effective for specific metals, and chromate, etc. More and more things are becoming a source of pollution and are becoming unusable.
Furthermore, even if they are mixed, it is not always possible to obtain a rust preventive agent that combines the advantages of both components; they may not dissolve each other, or the disadvantages of each component may appear, or the sustainability of the effect may be lost. In addition, nitrites can react with lower amines to form carcinogenic nitrosamines. The present inventors previously discovered that certain types of maleic acid copolymer-type oligosoaps have excellent general surface activities such as surface tension, emulsifying power, and dispersing power even if they do not have long-chain aliphatic groups. However, as a result of further research, we discovered that it not only has practical advantages such as low toxicity and stability, but also has excellent rust prevention properties against various metals. Based on these findings, the present invention has been completed.

i That is, the present invention is based on the general formula (in which R is a butyl group, X and Y represent a hydrogen atom, an alkali metal, an ammonium ion, an amino group, or an alkyl group, Or, if at least one of the maleic acid derivatives is a bulky monomer, the average number n of repeating units is 3 to 10, and if neither component is a bulky monomer, the average number n is 11 or more and several tens or less. The present invention provides a rust preventive agent comprising an alkyl vinyl ether-maleic acid derivative co-low polymer having a narrow polymerization degree distribution width expressed by:

In the present invention, the bulky monomer means a p-Tert octyl group or an isobutyl group in the case of an alkyl vinyl ether, and in the case of a maleic acid derivative, a maleic acid derivative other than maleic anhydride, such as diethyl maleate. etc.

Therefore, non-bulky monomers mean alkyl vinyl ethers or maleic acid derivatives other than those mentioned above. The alkyl vinyl ether-maleic acid derivative co-low polymer with a narrow polymerization degree distribution width used in the present invention is produced by a bulk polymerization method in which a maleic acid derivative and an alkyl vinyl ether are polymerized without using a chain transfer agent or a solvent. Proceed rapidly according to It can be prepared by

Generally, maleic acid derivatives are copolymerized with various vinyl monomers to give alternating copolymers.

However, alternating copolymers of maleic acid derivatives and alkyl vinyl ethers obtained by conventional methods have a high degree of polymerization, and the average number of repeating units ranges from several tens to thousands. Since the distribution width is wide, ranging from 2 to several thousand, its uses have been limited. Therefore, in order to obtain an oligomer with an extremely low degree of polymerization, it was necessary to carry out a fractional precipitation treatment of the obtained copolymer. 4 On the other hand, by allowing the polymerization reaction to proceed rapidly without using a chain transfer agent or solvent as described above, the number of repeating units increases due to the steric hindrance effect of bulky monomers such as maleic esters. However, oligomers with a low polymerization degree of 3 to 10 on average and a narrow distribution width can be obtained. Furthermore, even when using monomers that are not bulky, such as maleic anhydride or n-butyl vinyl ether, n is much smaller with this method than with conventional telomerization reactions; Although a low polymerization reaction is not effective, oligomers with an average n of 11 or more and several tens or less, including oligomers with a degree of polymerization of 10 or less, can be obtained. As maleic acid derivatives, maleic acid and similar unsaturated acids, their anhydrides, salts, esters, amides, etc. can also be used.

These are represented by the following general formula, where and each R'' are selected from hydrogen, methyl and ethyl groups, and Z
is selected from hydrogen, an alkyl group having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, and an alkali metal.

Examples include maleic acid, maleic anhydride, fumaric acid,
Methyl maleic acid, dimethyl maleic acid, ethyl maleic acid, diethyl maleic acid, dimethyl maleate, diethyl-dimethyl maleate, monomethyl-monomethyl maleate, dibutyl-diethyl fumarate, di-n-propyl-monomethyl fumarate, methyl-ethyl maleate Examples include rum maleate, monomethyl maleic anhydride, diethyl maleic anhydride, methyl ethyl maleic anhydride, sodium dimethyl maleate, potassium diethyl fumarate, and mixtures of these substances may also be used. Moreover, butyl is preferable as the alkyl group of the alkyl vinyl ether, which is the other component of the alternating copolymer.

Examples include n-butyl vinyl ether, i-butyl vinyl ether, etc. The copolymer thus obtained is saponified or esterified with an alkali or alcohol, and then purified by a conventional method. Examples of alkalis used in this case include ammonia, lithium hydroxide, sodium hydroxide, potassium hydroxide, and organic monoamines such as aniline, toluidine, pyridine, ethylamine, and monoethanolamine.Also, examples of alcohols include: Examples include methanol, ethanol, butanol, diethylene glycol, and glycerin.
These can be reacted alone or in combination of two or more. The rust inhibitor of the present invention usually contains the alkyl vinyl ether-maleic acid derivative co-low polymer at a concentration of 0.05 to
Used as a 3.0% aqueous solution.

The rust inhibitor of the present invention has low toxicity, stability, and rust prevention effect.
L-2 Rust prevention power (rust prevention power) test method Pour approximately 4 ml of sample aqueous solution into a test tube with a cap (10 mL), and add 4 to 1 unique test metal pieces (
Simultaneously soak 3 x 20
15°C) The change in the metal piece after standing for a predetermined number of days at a relative humidity of 93% is evaluated by visually observing the change.

The evaluation criteria are as follows.

Evaluation Surface condition 5 No change at all 4 Slight decrease in gloss, pitting formed in a very small part, slight contamination in solution 34 Change slightly increased 2 Significant change, rust on about half of the surface (The fruit is excellent.

Especially for a wide variety of metals, such as soft iron, steel, aluminum,
It has excellent rust prevention properties against brass, copper, lead, tin, galvanized iron, solder, etc. Next, the present invention will be explained in more detail based on Examples and Reference Examples.

The alkyl vinyl ether-maleic acid derivative co-low polymer used in the Examples (prepared according to the method of Reference Examples described later) and the test method for rust prevention ability are as follows.

1 Alkyl vinyl ether maleic acid derivative co-low polymer 1 Very changed, completely covered with rust, solution
There is no significant discoloration and formation of precipitate Reference example n-butyl vinyl ether 60.1g (0.60 mol)
, diethyl maleate 103.3V (0.60 mol) and AIBN 3.3f (0.02 mol) were placed in a 1e capacity three-way separable flask and heated to 70°C at normal pressure while stirring in a nitrogen stream. Even when heating is stopped, the temperature rises rapidly, and after reaching 145°C, the temperature drops.

The reaction time during this period is a short time of 6 gin or less. The mixture was returned to room temperature and the evaporated components were evaporated under reduced pressure. The yield of the residue was 131q (yield 80%), and the number of repeating units of the alternating copolymer measured by the boiling point increase method was 4 on average. Also,
Gel permeation chromatography (GPC) confirmed that it had a degree of polymerization of mostly 3, 4, and 5, which is consistent with the results obtained by the boiling point elevation method. A part of the alternating copolymer thus obtained was dissolved in ethanol, and an aqueous solution containing sodium hydroxide in an amount equivalent to 1.1 times the ester group content or O city times the content in a minimum amount of water was added. After heating under reflux for 2 hours, the resulting precipitate was separated, dissolved in warm water, and then poured into ethanol for precipitation, which were repeated for purification. In this way, a copolymer with a saponification degree of 100% or 45% (respectively calculated from the molecular model structure and Na analysis value) was obtained depending on the amount of sodium hydroxide added. All of these were water-soluble. Example 1 C4D-NalOO, C4D-Na43, C4M-N as alkyl vinyl ether-maleic acid derivative co-low polymer
The antirust ability was tested using alOO, C4M-Na5O, as a 1% aqueous solution. The results are shown in Table 2. From this result, the rust preventive of the present invention has excellent rust preventive power overall, but especially the alkyl vinyl ether-maleic acid co-low polymer in which R in the above general formula is a butyl group can be used with various metals. It can be seen that it has anti-rust power (rust-preventing power).

Example 2 Steel B was immersed in C4DNa-43 aqueous solution (1%),
After being left at room temperature for two years, no changes were observed in either the metal pieces or the solution.

Example 3 Steel A was immersed in a C4DNa-43 aqueous solution (1%), and 3
As a result of standing at 0°C for 10 days, no change was observed in the appearance of the metal piece, and there was no change in weight at all (a). 001q/1
0d1 reference: soft iron, distilled water; -54.0y/10d).

Claims (1)

[Claims] 1 General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (R in the formula is a butyl group, X and Y are hydrogen atoms,
When it represents an alkali metal, ammonium ion, amino group, or alkyl group, and at least one of the component alkyl vinyl ether or maleic acid derivative in the above repeating unit is a bulky monomer, the average number of repeating units n is 3 to 10.
, in the case of monomers in which neither component is bulky, the average n
is 11 or more and several dozen or less).