JPS6411075B2 - - Google Patents

Description

[Detailed description of the invention]

A. Industrial Application Fields The present invention is a chlorinated polyolefin paint that exhibits superior performance in terms of long-term weather resistance, adhesion to objects to be coated, and compatibility with other resins compared to conventional chlorinated polyolefin paints. Regarding. B. Prior Art Chlorinated polyolefins (hereinafter abbreviated as CPO), which are made by chlorinating polyolefins such as natural rubber, synthetic isoprene rubber, polypropylene, and polyethylene, to a chlorine content of 60 to 75% by weight, are produced using inexpensive organic solvents (e.g., xylene, It is easily soluble in toluene, etc.), easy to apply by brushing, spraying, dipping, etc., and dries quickly.The dried coating film has excellent acid resistance, alkali resistance, oil resistance, and chemical resistance. Because it has good properties such as being self-extinguishing and self-extinguishing, it is widely used as an extremely useful coating material in the fields of paints, printing inks, coating agents for film sheets, adhesives, etc. Particularly in the paint field, it is used not only for ships but also for land structures such as long bridges, giant tanks, and land containers. Recently, it has also begun to be used as a paint for plastics, and its uses are diverse, with performance requirements tailored to each use. C. Problems to be Solved by the Invention However, these CPOs almost universally have the following drawbacks, resulting in various difficulties and limitations in their use. The first drawback is that the addition of a low molecular weight plasticizer causes staining and cracking of the paint film. Since the CPO film alone is hard and brittle, a plasticizer is often required for practical use. However, since commonly used plasticizers have a low molecular weight, they migrate to the upper part of the coating film or escape from the coating film over time, resulting in staining and cracking of the coating film.
The second drawback is that it has poor affinity for polar substances and has difficulty adhering to objects to be coated, especially metal surfaces. Considering the application of CPO, adhesion to metal surfaces is an important factor in paint performance. The main reason for poor adhesion to metal surfaces is usually
Since CPO does not have functional groups containing nitrogen or oxygen,
This is thought to be due to the inability to form strong hydrogen bonds with hydroxyl groups on the metal surface. The third drawback is that it has poor compatibility with other resins. Usually CPO paint is
It is rare that CPO is the only resin component; petroleum resin, coumaron resin, alkyd resin, etc. are also used in combination. This may be used in combination for the purpose of improving the physical properties of the paint, but it may also be used in combination simply to reduce costs. For example, an alkyd resin is usually used in topcoat paints that use CPO as a binder for corrosion protection. This is added not only to improve weather resistance, photo selectivity, etc., but also to reduce costs. However, traditional
CPO has good compatibility with long-oil alkyds, but
It does not mix well with short oil length alkyds. If they are not mixed together, problems such as a decrease in gloss will naturally occur, which means that alkyds with short oil lengths cannot be used. To overcome the first drawback, that is, the reduction in long-term weather resistance due to the addition of low-molecular-weight plasticizers, the present inventors have already developed a single film and a flexible CPO (specially Gansho 58-
No. 236403). Countermeasures for the second and third drawbacks, namely adhesion to polar substances and compatibility with other resins, have already been reported (Tokkaicho 48-
No. 102892). By grafting a monomer containing oxygen, this improves adhesion to iron surfaces and at the same time
It is reported that the compatibility with other resins could be improved. However, an excellent CPO that simultaneously covers these three drawbacks has not yet been developed. Some of the conventionally known CPOs are compatible with other resins, but because they are not flexible, plasticizers must be added, resulting in stains in the short term and problems in the long term. The current situation is that there are problems with cracking. In addition, the inventors developed the previous patent application filed in 1983.
CPO No. 236403 is flexible and does not require a plasticizer, but it has a problem of poor adhesion to steel surfaces. D. Means and Effects for Solving the Problems Therefore, the present inventors conducted various studies to develop a CPO that overcomes these three drawbacks at the same time.As a result, the present inventors discovered that the polyolefin has a hydroxyl group, a carboxyl group, and an acid anhydride group. After grafting a reactive monomer, it was chlorinated to form an internally plastic CPO. It was discovered that this product had extremely excellent performance that had not been found before, and this led to the present invention. Modification with internal plasticity used in the present invention
CPO is produced by heating and melting an olefin or diolefin polymer such as natural rubber, synthetic isoprene rubber, polypropylene, or polyethylene, or by homogeneously dissolving it in an appropriate solvent (xylene, toluene, etc.). Alternatively, an oxygen-containing reactive monomer having an acid anhydride group and a radical generator are applied. The obtained grafted product is dissolved in a chlorine-resistant solvent such as carbon tetrachloride, trichloride, chloroform, etc., and then a peroxide such as benzoyl peroxide or ketone peroxide is used as a chlorination catalyst, or by a method such as ultraviolet irradiation. It is then chlorinated. After chlorination to a chlorine content of 50% by weight or more and less than 60% by weight, replacing the reaction solution with an aromatic, ester, or ketone solvent will result in modification with the desired internal plasticity.
You can get CPO. Examples of reactive monomers having hydroxyl groups, carboxyl groups, and acid anhydride groups used here include 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate,
-Hydroxyethyl methacrylate, acrylic acid, methacrylic acid, maleic anhydride, etc. In addition, examples of radical generators include hydroperoxide, dialkyl peroxide,
Examples include organic peroxides such as ketone peroxide, peroxy ester, and alkyl peroxide, and organic azo compounds such as azobisisobutyronitrile and azobisisopropylonitrile. E Example Next, typical examples of the present invention will be shown.
The invention is not limited to this example. The paint composition of the present invention is a simple formulation example to clarify the difference from the comparative example. Compatible resins such as petroleum resins, alkyd resins, phenolic resins, acrylic resins, vinyl chloride resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, bituminous materials, etc. used in [Example 1] 1 kg of polyethylene with an average molecular weight of 2800 and a density of 0.92 was placed in a reaction tank equipped with a stirrer and a condenser.
After melting at 175°C, the air in the reaction tank was sufficiently purged with nitrogen gas. Next, 200 g of maleic anhydride was added into the reaction tank, and while stirring, 20 g of benzoyl peroxide was added dropwise over 1 hour. After reacting for an additional hour, the reactants were transferred to another chlorination reaction tank, which was charged with carbon tetrachloride.
10 was added and uniformly dissolved under pressure at 90°C, and the air in the tank was sufficiently purged with nitrogen gas.
Next, gaseous chlorine was blown into the chlorination reaction tank while being irradiated with ultraviolet light, and the degree of chlorination was 52, 55, and 57, respectively.
When the concentration reached 68% by weight, samples were sequentially taken out from the bottom of the reaction tank. After thoroughly degassing each of these samples, they were transferred to a concentrating vessel, the reaction solvent was distilled off, xylene was added to these samples, the solvent was completely replaced with xylene, and each sample was made into a xylene solution with a solid content of 40% by weight. was prepared. Furthermore, Comparative Example 1 was prepared by using the same method as above to prepare polyethylene with a degree of chlorination of 57% without grafting maleic anhydride. For each sample of Example 1 above, the sample of Comparative Example 1, and the sample of Comparative Example 2 below, paints were prepared using a 40% by weight xylene solution with the formulations shown in Table 1, and their performance tests were conducted. Table 2 shows the results.
Further, Table 3 shows the compatibility test results.

[Table] After kneading each of the formulations in Table 1 for 3 hours in a sand mill, the paint viscosity was adjusted to a constant value (72 KU) and used as a sample for paint performance testing. In all tests except the adhesion test, the test piece used was a polished steel plate treated with a wash primer. The test piece for the adhesion test was painted directly onto a polished steel plate. In addition, the dry coating thickness is
It was set to 80μ.

【table】

[Table] Based on the remaining rate of the paint film.

[Example 2]

In a reaction tank similar to Example 1, an average molecular weight of 5800 was added.
After melting 1 kg of polypropylene with a density of 0.91 at 180°C, the air in the reaction tank was sufficiently purged with nitrogen gas. Then maleic anhydride is added to the tank.
250 g of benzoyl peroxide was added over 1 hour while stirring. After reacting for an additional hour, the reactant was transferred to another chlorination reaction tank, 10% of carbon tetrachloride was added thereto, and the mixture was uniformly dissolved under pressure at 100°C. After that, the air in the tank was thoroughly purged with nitrogen gas. did. Next, gaseous chlorine was blown into the tank while irradiating it with ultraviolet rays, and when the degree of chlorination reached 53% by weight, the reaction was stopped and degassed. Thereafter, the reaction product was transferred to a concentrator, the reaction solvent was distilled off, and xylene was added thereto to obtain a 40° C. xylene solution. Furthermore, the degree of chlorination of polypropylene that is not grafted with maleic anhydride by the same method as above.
Comparative Example 3 was prepared at 53%.

【table】

[Table] The formulation in Table 4 was kneaded in a sand mill in the same manner as in Example 1, prepared to 72 KU, and then applied to a polished steel plate coated with a wash primer to a film thickness of 80μ, and after drying was used for testing. did. However, for the adhesion test, the paint was applied directly to the polished steel plate without applying the wash primer.

[Table] was examined. The evaluation was based on the residual rate of the paint film.

[Example 3]

average molecular weight in a reaction tank similar to Example 1.
8000, add 200g of atactic polypropylene with a softening temperature of 90℃ and 1 xylene, and raise the liquid temperature to 100~
After completely melting while maintaining the temperature at 105°C, the air in the reaction tank was sufficiently purged with nitrogen gas. Next, while maintaining the liquid temperature at 100 to 105°C, 40 g of methacrylic acid in which 5 g of benzoyl peroxide was dissolved was added dropwise into the reaction tank over 1 hour.
After reacting for an additional hour, the reaction solution was cooled to room temperature and then taken out from the reaction tank. The reaction product was then precipitated into acetone, filtered off, washed, and dried under reduced pressure at room temperature. The obtained product was subjected to a chlorination reaction in the same manner as in Example 2 to obtain a 40% xylene solution of methacrylic acid-modified chlorinated atactic polypropylene with a degree of chlorination of 53% by weight. In addition, Comparative Example 5 was prepared using the same method as above to prepare atactic polypropylene with a degree of chlorination of 53% without grafting methacrylic acid. The formulations in Table 7 were kneaded in a sand mill in the same manner as in Example 1, prepared to 72 KU, and then applied to a polished steel plate coated with a wash primer to a film thickness of 80 μm, and after drying, the mixture was tested. However, for the adhesion test, no wash primer was applied.
Painted directly onto a polished steel plate was used.

【table】

【table】

【table】

Claims (1)

[Claims] 1 A chlorinated polyolefin with internal plasticity modified with a reactive monomer having a hydroxyl group, a carboxyl group, or an acid anhydride group and chlorinated to a chlorine content of 50% by weight or more and less than 60% by weight is used as the main coating film-forming element. A coating composition that does not use plasticizers.