JPS5932501B2 - paint composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to a coating composition.

More specifically, it is produced using a vinyl-substituted aromatic hydrocarbon containing a polar group at the polymer end and a polymer of conjugated dienes as one component, and is mainly used for concrete, ships, bridges, steel plates, road markings, The present invention relates to coating compositions used for building materials and the like. Conventionally, styrene-butadiene-based polymers have been used as part of resins for paints that require water resistance, chemical resistance, etc. for concrete, ships, etc. However, since these styrene-butadiene-based polymers are manufactured by radical polymerization, they have a wide molecular weight distribution and therefore contain a considerable amount of low molecular weight polymers.
Moreover, it was a random copolymer in which styrene and butadiene were uniformly distributed on the polymer chain. In addition, since these polymers are usually polymerized by emulsion polymerization, the presence of trace amounts of emulsifiers cannot be avoided. Therefore, when a coating composition is manufactured using these polymers as a vehicle binder, the resulting coating film is It had drawbacks such as insufficient water resistance, weather resistance, and coating strength. Therefore, the present inventors produced a polymer having a narrow molecular weight distribution and a low content of low molecular weight polymers by an anionic living polymerization method using a polymerization method that does not use any emulsifier. Attempts were made to improve the disadvantages of polymers.

However, a coating composition manufactured by blending an inorganic pigment with a styrene-butadiene polymer as a main component manufactured by an anionic living polymerization method using an organic alkali metal compound as a polymerization initiator cannot be manufactured by using this polymer. The dispersibility of the pigment in the vehicle binder is poor, and the coating film obtained when blending at a practical pigment concentration is obtained by using a polymer produced by emulsion polymerization method as the vehicle binder. It has been found that although it has superior weather resistance compared to paint films, it has inferior gloss and water resistance. On the other hand, the anionic living polymerization method has the characteristic that the composition, molecular weight, molecular weight distribution, molecular structure, etc. of the polymer can be changed relatively freely. Styrene-butadiene polymers are used as thermoplastic elastomers for shoe soles, hot melt adhesives, plastic blends, etc. when the styrene to butadiene composition ratio is approximately 30:70 to 40:60; is about 5
Polymers with a ratio of 0:50 to 70:30 are used as transparent soft resins as materials for stretch films, toys, etc. In addition, the styrene to butadiene composition ratio is approximately 75 to 25.
A 90:10 polymer is a transparent resin with excellent cold resistance and impact resistance, and is used in the form of films and sheets for food packaging materials. Furthermore, these polymers can be used as binders in coating materials, such as ink binders,
It is also used as a surface treatment agent for seaweed. Therefore, if the dispersibility of pigments etc. in the polymer vehicle of vinyl-substituted aromatic hydrocarbons and conjugated dienes polymerized by anionic lipping polymerization method is improved, and inorganic pigments of practical agricultural grade are blended into this polymer, If the coating film obtained from the produced coating composition has excellent physical properties such as gloss, water resistance, and weather resistance, it will be of industrial value.

Therefore, the present inventors have conducted extensive research to improve the dispersibility of pigments in polymers produced by solution polymerization that do not contain any emulsifiers and have few low molecular weight components, and to improve the physical properties of coating films. As a result, when a polymer containing a terminal polar group obtained by polymerizing by an anion lipping polymerization method and introducing a polar group such as a carboxyl group or a hydroxyl group at the terminal end of the polymer is blended with an inorganic pigment, Although the amount of polar groups introduced was very small, a surprisingly significant effect was observed in improving the dispersibility of the inorganic pigment in the polymer, and a paint composition containing a practical concentration of pigment was found. The present inventors have discovered that the present invention is highly effective in improving the water resistance and gloss of coating films obtained from objects, and have completed the present invention.

Conventionally, radical polymers produced by emulsion polymerization using a large amount of chain transfer agent have shown good pigment dispersibility to some extent, even without intentionally introducing carboxyl groups through copolymerization or the like.The reason for this is chain transfer. This is thought to be due to the polar functional groups introduced by agents, initiators, etc. The present invention is based on the fact that a polymer vehicle of non-polar monomers that is polymerized by anionic lipping polymerization and has no functional groups does not exhibit good pigment dispersibility, and that the pigment dispersibility has been dramatically improved. This is the first study to disclose that the introduction of a polar group at the end of a polymer is effective for achieving this goal. That is, the present invention provides at least one monomer selected from the group of vinyl-substituted aromatic hydrocarbons and conjugated dienes, which is polymerized using an alkali metal or organic alkali metal polymerization initiator under polymerization conditions. Oxygen, nitrogen, sulfur or This coating composition contains a polymer containing a chlorine-containing polar group as one component, and contains at least one type of inorganic pigment. Figure 1 shows the relationship between pigment concentration and paint film gloss for polystyrene, Figure 2 shows the relationship between pigment concentration and paint film gloss for styrene-butadiene block copolymer, and Figure 3 shows the relationship between pigment concentration and paint film gloss for styrene-butadiene block copolymer. Figure 4 shows the relationship between pigment concentration and paint film gloss for styrene-butadiene random copolymers produced by anionic lipping polymerization method, and Figure 4 shows the relationship between pigment concentration and paint film for styrene-butadiene block copolymers with different molecular weights. The relationship with gloss,
This is a comparison between those with and without terminal polar groups, respectively.

Furthermore, FIG. 5 shows the relationship between pigment concentration and coating gloss for styrene-butadiene block copolymers having various terminal polar groups. Furthermore, Figure 6 shows a microscopic photograph of titanium oxide (rutile type) used as a pigment, Figure 7 shows a microscopic photograph of a coating film prepared by blending titanium oxide with a polymer that does not have terminal polar groups, and Figure 8 shows a microscopic photograph of titanium oxide (rutile type) used as a pigment. A photomicrograph of a coating film prepared by blending titanium oxide with a polymer having terminal carboxyl groups is shown. Vinyl-substituted aromatic hydrocarbons in the present invention include, for example, styrene,
There are various alkylstyrenes such as alpha methylstyrene, vinyltoluene and the like.

Examples of conjugated dienes include 1,3-butadiene,
Examples include isoprene and piperylene. Furthermore, the polymer referred to in the present invention not only includes homopolymers and copolymers of the above substances, but also includes block copolymers.

The alkali metals used as polymerization initiators in the present invention include lithium, sodium, and potassium, and the organic alkali metal compounds include naphthalene complex compounds such as lithium, sodium, and potassium, or alkyl or aryl alkali metal compounds such as butyllithium. Can be used.

Furthermore, it is also possible to use organic dilithium compounds and organic polylithium compounds as polymerization initiators, and when an organic dilithium compound is used as a polymerization initiator, the effects of the present invention can be obtained by using an organic monolithium compound as a polymerization initiator. It becomes even more noticeable than when it is used. In the present invention, the polar reactants that react with the polymer containing terminal alkali metals include carbon dioxide gas, oxygen, ethylene oxide, phthalic anhydride, sulfur, nitrogen-containing or chlorine-containing compounds such as phosgene, and mixtures thereof. , anything that reacts with the terminal alkali metal may be used.

Alternatively, it may be a product obtained by polymerizing several molecules of a polymerizable polar monomer such as methyl methacrylate (MMA) or vinyl pyridine (VP). Furthermore, salts or hydrolysates thereof and mixtures thereof may also be used.
In the reaction between the polar reactant and the polymer-terminated alkali metal, some reactions involve a coupling reaction, but there is no problem even if the coupling reaction occurs partially.
The polar groups that can be attached to the end of the polymer are oxygen,
A group containing nitrogen, sulfur, or chlorine, examples of which are -COOM, -0M, -SM, -SO3M (where M represents hydrogen or a monovalent metal, 1C-C6H4-C-0M1
-(MMA)n and its hydrolyzate (however, the number of n is not particularly limited here, but is usually used in the range of n=l to 10), -(P)n and its hydrochloride, etc. However, the number of n is not particularly limited here, but is usually used in the range of n=1 to 10).

The term "terminal" as used in the present invention means one or more terminals of a polymer molecular chain, and the number of terminals that can be present in a polymer molecule varies depending on the type of polymerization initiator used.

For example, when an organic monolithium compound is used as a polymerization initiator, a chain polymer is obtained, and it is possible to have a polar group only at one end of this polymer. A chain polymer can also be obtained when a system polymerization initiator is used, but it is possible to have polar groups present at both ends of this polymer.

In addition, in a star-shaped polymer obtained by crosslinking a chain polymer containing an alkali metal at the end using a crosslinking agent such as divinylbenzene, the central and It is also possible to have a polar group present at the end. A star-shaped polymer in which a polar group is present in this manner is also included in the term "polymer containing a polar group at the polymer end" as used in the present invention. In addition, in the present invention, when a polymer is metallated using an organic alkali metal compound or the like to add an alkali metal to the main chain of the polymer, the carbon bonded to the alkali metal introduced by metalation is It is considered to be the end of one molecule.

Therefore, a polymer in which a polar group is introduced by reacting the alkali metal bonded to such a polymer with a polar reactant is also included in the polymer containing a polar group at the polymer terminal in the present invention. Polymers containing these terminal polar groups can be produced by various methods.

For example, by polymerizing styrene and butadiene in a xylene solvent in a nitrogen atmosphere using an alkyldilithium polymerization initiator and treating the resulting polymer with carbon dioxide gas, a polymer containing carboxylic acid lithium salt at both ends can be produced. can be manufactured. The polymer containing carboxylic acid lithium salt at both ends of the polymer produced in this way is blended with pigments, etc. in the state of a polymer solution containing the polymerization solvent used in the solution polymerization method, and then used as a coating material. It is possible to produce compositions for use.

However, before blending, water, alcohol, or other additives that are equimolar or slightly more than equimolar to the alkali metal atom capable of initiating polymerization in the alkali metal or organic alkali metal compound used as a polymerization initiator are added to the polymerization solution. It is preferable to add a Lewis acid or the like to remove the alkali metal present at the terminal end of the polymer from the polymer, thereby reducing the viscosity of the polymer solution. Further, the polymer thus produced can be precipitated or gram-ized by a methanol precipitation method, a steam stripping method, etc., and then made into a dry powder and then blended to produce a coating composition.

Furthermore, it is also possible to manufacture a coating composition by evaporating a portion of the polymerization solvent from the polymerization solution obtained in this way and concentrating it, followed by blending. The reason for the improved dispersibility of the inorganic pigment in the polymer produced by the anionic lipping polymerization method in the coating composition of the present invention is that the polar group at the end of the polymer is oriented and adsorbed on the surface of the inorganic pigment particle, and the pigment particle This is thought to be because the surface is coated with the polymer, which prevents aggregation of pigment particles and improves the dispersibility of the pigment particles in the vehicle containing the polymer.

Furthermore, the reason for the remarkable improvement in the gloss and water resistance of coating films obtained from coating compositions prepared by blending inorganic pigments at practical concentrations is due to the improvement in the dispersibility of pigment particles in the polymer. Because the terminal polar groups of the polymer are oriented and adsorbed on the surface of the pigment particles, the adhesion between the pigment and the vehicle containing the polymer as a component is extremely good. This is thought to be due to the fact that the number of micropores present in the polymer is significantly reduced compared to when a polymer without terminal polar groups is used. Next, the present invention will be explained in more detail with reference to Examples. Example 1 A styrene polymer with a number average molecular weight of 50,000, which does not contain terminal polar groups and which is manufactured by an anionic lipping polymerization method, and a styrene polymer containing a carboxyl group at the terminal end of a polymer with the same molecular weight are mixed with an inorganic pigment (titanium ryltyl oxide). mold) and a diluent (xylene) by ball milling.
The mixture obtained by time mixing was applied to a thoroughly cleaned mild steel plate using a film applicator, and the 600 specular reflectance (gloss) of the coating was dried at room temperature. The results are shown in Figure 1. It turned out to be a good idea.

Figure 1 shows that the coating film gloss of polymers containing terminal carboxyl groups is almost the same at low pigment concentrations, but significantly superior at high pigment concentrations, compared to polymers containing no terminal polar groups. That is clear. Example 2 A polymer with a molecular weight of 50,000, containing no terminal polar groups, produced by an anionic lipping polymerization method, and containing 85% by weight of styrene and 1% by weight of butadiene.
A styrene-butadiene tapered block copolymer with a composition of 5% by weight (styrene block ratio 700f), and a tapered block copolymer containing a carboxyl group at one end and both ends of a polymer having the same molecular weight and composition. (styrene block rate 70%), pigment titanium oxide (rutile type) and diluent (xylene) were added, and blends with different pigment concentrations were made using a ball mill in the same manner as in Example 1. The results of examining the relationship between gloss are shown in Figure 2.

The figure shows that when comparing the coating film gloss of a polymer that does not contain a polar group at the polymer end, a polymer that contains a carboxyl group at one end of the polymer, and a polymer that contains carboxyl groups at both ends of the polymer, it is found that the film gloss is low. Although the gloss at different pigment concentrations is the same, at high pigment concentrations, a polymer containing one terminal carboxyl group has higher gloss than a polymer containing no terminal polar group, and a polymer containing both terminal carboxyl groups has even higher gloss. It is clear that the gloss is high. Example 3 A styrene-butadiene random copolymer with a composition of 85% by weight of styrene and 15% by weight of butadiene, which does not contain a polar group at the terminal and is produced by an anionic lipping polymerization method, and a polymer with the same composition containing a carboxyl group at one end. Pigment titanium oxide (rutile type) and diluent (xylene) were added to the random copolymer, and blends with different pigment concentrations were performed using a ball mill in the same manner as in Example 1, and the relationship between pigment concentration and coating gloss was investigated. The results are shown in Figure 3.

The figure shows that when comparing the coating gloss of a random copolymer that does not contain a polar group at the polymer end and a random copolymer that contains a carboxyl group at one end of the polymer, the gloss is the same at a low pigment concentration, but the gloss is high. It is clear that in terms of pigment concentration, a polymer containing one terminal carboxyl group has higher gloss than a polymer containing no terminal polar group. Example
4 Tapered block copolymers with number average molecular weights of 30,000, 50,000, and 100,000 that do not contain terminal polar groups and have a composition of 85% by weight styrene and 15% by weight butadiene, produced by anionic lipping polymerization method, and polymers with the same composition. Pigment titanium oxide (rutile type) and diluent (xylene) were added to tapered block copolymers with molecular weights of 30,000, 50,000, and 100,000 containing a carboxyl group at one end, respectively, and the same was used in Example 1 using a ball mill. Figure 4 shows the results of examining the relationship between pigment concentration and coating gloss by mixing different pigment concentrations using the method described above.

The figure shows that for all copolymers with different molecular weights, those containing carboxyl groups at one end of the polymer have better coating gloss at the same pigment concentration than those containing no polar groups.

Example 5 Styrene containing no terminal polar group 85% by weight produced by anionic lipping polymerization method, butadiene 1
Example 1 Using a styrene-butadiene copolymer with a composition of 5% by weight and a number average molecular weight of 50,000 and a polymer containing carboxyl groups at both ends of the polymer having the same composition, the formulations shown in Table 1 were prepared using a Bournon mill. was carried out under the same conditions.

The mixture obtained from the formulation shown in Table 1 above was applied to a thoroughly cleaned mild steel plate using a film applicator,
Microscopic photographs of the coating film after drying at room temperature and the pigment titanium oxide (rutile type) are shown in FIGS. 6 to 8.

In addition, the respective gloss levels were as shown in Table 2. In addition, FIG. 7 shows the case where a polymer having no terminal polar group is used, and FIG. 8 shows the case where a polymer having a terminal carboxyl group is used. Table 2 and Figures 7 to 8 show that the gloss of the coating film obtained from the polymer that does not contain polar groups is low, and that the pigment particles are aggregated in this coating film, while the pigment particles contain terminal carboxyl groups. The gloss of the coating obtained from the polymer is high, and it is clear that the pigment particles are uniformly dispersed in the coating.

This result shows that the pigment particles aggregate in the low-gloss coating, but are uniformly dispersed in the high-gloss coating. Example 6 A polymer with a composition of 85% by weight of styrene and 15% by weight of butadiene and a molecular weight of 50,000, produced by an anionic lipping polymerization method and containing no terminal polar groups, and a polymer with the same composition and the same molecular weight containing carboxyl groups at both ends. Polymers, and polymers with the same composition and the same molecular weight.Polymers containing hydroxyl groups at both ends, and polymers with the same composition and the same molecular weight.Polymers containing sulfur at both ends, and polymers with the same composition and the same molecular weight. Pigment titanium oxide (rutile type) and diluent (xylene) were added to a polymer containing an average of 5 molecules of vinylpyridine hydrochloride at both ends, and the pigment concentration and coating film were mixed in the same manner as in Example 1. The results of examining the relationship between glossiness are shown in FIG.

The figure shows that at low pigment concentrations, the coating film gloss at the same pigment concentration is approximately the same for polymers containing polar groups such as carboxyl groups, hydroxyl groups, sulfur, and vinylpyridine hydrochloride at both ends of the polymer, compared to polymers that do not contain terminal polar groups. Although identical, it is clear that at high pigment concentrations, the film gloss of a polymer formulation containing polar groups at both ends of the polymer is significantly superior to that of a polymer formulation containing no terminal polar groups. . That is,
It can be said that the pigment dispersibility in a polymer containing a polar group at the polymer end is clearly superior to the pigment dispersibility in a polymer not containing a polar group at the end. Example
7 Polymer manufactured by anionic lipping polymerization method Contains a carboxyl group at the end, number average molecular weight 60,000, styrene 8
5% by weight of a polymer with a composition of 15% by weight of butadiene, and a 30% xylene solution viscosity of a polymer with the same composition (25°C
) and a polymer containing no terminal polar group produced by the same anionic lipping polymerization method, and a polymer produced by the radical polymerization method having the same composition and the same 30% chymilene solution viscosity (25°C) of the polymer. make use of,
The formulations shown in Table 3 were prepared.

The formulations shown in Table 3 above were mixed using a ball mill for about 10 hours. A formulation (white enamel) containing each of the obtained polymers as one component was applied to a thoroughly cleaned mild steel plate using a film applicator and dried at room temperature, after which various coating film performance tests were conducted. The results are shown in Table-4. Formulation A in the above table is a coating film containing a polymer containing terminal polar groups,
B is a coating film composed of a polymer that does not contain terminal polar groups;
C is a coating film containing a polymer produced by radical emulsion polymerization.

Adhesion to the substrate was determined by the cross method of the cross-cut test. The impact resistance was determined by dropping a steel ball of 6.35H11φ onto the test coating from a height of 50c7rL and visualizing changes in the coating. Salt water resistance, salt water spray resistance, and accelerated weather resistance are all determined by visually inspecting the surface of the coating film. The judgment was based on the following criteria. As is clear from Table 4 above, the coating film of the present invention has better gloss and adhesion to the substrate than the coating film produced by anionic lipping polymerization method and composed of a styrene-butadiene copolymer that does not contain terminal polar groups. It also shows excellent performance in terms of hardness, salt water resistance, and salt spray resistance, and also has excellent impact resistance and accelerated weather resistance compared to coatings made from styrene-butadiene copolymers produced by radical emulsion polymerization. It is clear that it shows excellent performance and also shows excellent performance in salt water resistance and salt water spray resistance.

[Brief explanation of the drawing]

Figures 1 to 5 show the relationship between pigment concentration and coating gloss for various polymers, Figure 6 shows microscopic photographs of pigmented titanium oxide, and Figures 7 to 8 show microscopic photographs of pigmented coatings. show.

Claims (1)

[Claims] 1 At least one terminal obtained by polymerizing at least one monomer selected from the group of vinyl-substituted aromatic hydrocarbons and conjugated dienes using an alkali metal or organic alkali metal polymerization initiator under polymerization conditions. Polar polymers containing oxygen, nitrogen, sulfur, or chlorine at the terminals obtained by treating a polymer containing an alkali metal with a polar reactant containing oxygen, nitrogen, sulfur, or chlorine that reacts with the alkali metal at the polymer terminals. A coating composition comprising a group-containing polymer as one component and at least one type of inorganic pigment mixed therein.