JPH0216939B2 - - Google Patents

Description

[Detailed description of the invention]

Air pollution has become a problem in recent years, and reducing the amount of organic solvents used in paints has become an important issue. Therefore, powder coatings, solvent-free coatings, water-soluble coatings, high-solids coatings, etc., have been developed to eliminate pollution. However, in the case of high solids paints, it is difficult to simultaneously satisfy high solids content, low viscosity, and coating film performance. In the case of alkyd resins, the methods for achieving high solidity differentiation and low viscosity can be roughly divided into: (1) using a solvent with strong solubility, (2) reducing the molecular weight of the resin, and (3) reducing the molecular weight of the resin. Possible methods include chaining the molecular structure. However, for method (1), there is currently no solvent suitable for use in paints that dry at room temperature. In other words, the use of highly soluble solvents damages the underlying paint film and causes a lifting phenomenon when the paint film is repainted. In method (2), drying is slow and the molecular weight of the cured coating film is not sufficiently large, so it is difficult to obtain good coating performance in terms of hardness, solvent resistance, chemical resistance, water resistance, physical properties, etc. As for method (3), it is possible to lower the viscosity by using many raw materials such as adipic acid and ethylene glycol and making the molecular structure of the alkyd resin a linear structure, but the secondary transition temperature of the resin There are disadvantages in that drying is slow due to extremely low hardness, and the hardness, stain resistance, solvent resistance, etc. of the cured coating film are not sufficiently improved. Conventionally, as room-temperature drying resins, boiled oil, urethanized oil, drying oil, etc. have been used, such as linseed oil-modified alkyd resin with an oil length of 40 to 80%, safflower oil-modified alkyd resin, soybean oil-modified alkyd resin, and dehydrated castor oil-modified resin. Alkyd resins, tung oil-modified alkyd resins, etc. are known, and there are also modified alkyd resins made by copolymerizing these alkyd resins with vinyl monomers, or modified with phenolic resins, epoxy resins, petroleum resins, rosins, etc. Known as a paint vehicle. Furthermore, it is also known that alkyd resins modified with maleated oil, which is a combination of polybutadiene made from the _C4 fraction of petroleum and maleic acid, have improved corrosion resistance. However, it is generally difficult for these paint vehicles to balance drying properties, coating film performance, high solids content, and low viscosity as resins that dry at room temperature. That is, as the resin becomes more solid and has a lower viscosity, the drying properties and performance of the coating film tend to decrease significantly. The present invention provides an oxidatively polymerizable modified alkyd resin composition for paints which has improved these drawbacks. In the present invention, (A) an oxidatively polymerizable oil component with an iodine value of 40 or more is made to have an oil length of 25 to 80%, and a viscosity of 0.5 to 13.0 poise (25°C, diluted to 60% by weight with xylene). (measured by Gardner method), acid value 3~
97 to 50 parts by weight of oil-modified alkyd resin of 30, (B)
The total amount of (A) and (B) is in the range of 3 to 50 parts by weight of the aryl alkoxy compound of hexamethylolmelamine.
The present invention relates to an oxidatively polymerizable modified alkyd resin composition for paints, which contains an amount of 100 parts by weight, and optionally contains (C) a diluting solvent. The oil-modified alkyd resin in the present invention is produced by an ester conversion method, a fatty acid method, or the like. An example of the former method is to convert polyhydric alcohol in an amount equivalent to or more than the oil component in the presence of a transesterification catalyst such as lithium hydroxide, lithium naphthenate, lead oxide, etc.
After reacting for about 0.5 to 2 hours at ℃, polybasic acid, remaining polyhydric alcohol, and modifying components such as epoxy resin and phenol resin are added as necessary, and half esterification is carried out at a temperature of about 180℃ for about 1 hour. 200
Raise the temperature to ~240°C and carry out the reaction to the end point. An example of the latter method involves reacting oil components, polyhydric alcohols, polybasic acids, and optionally modified components at a temperature of around 180°C for about 1 hour, and then raising the temperature to 200 to 240°C to complete the reaction. . As the oil component having an iodine value of 40 or more and having oxidative polymerizability used in the present invention, soybean oil, safflower oil, tall oil, dehydrated castor oil, cottonseed oil, tung oil, castor oil, rice bran oil, etc. are used. These fatty acids and the like are used. In addition, these coconut oils with an iodine value of 40 or less, palm oil, versatile acid (synthetic saturated fatty acid, trade name of Schiel Chemical Co., Ltd.), Cardiula E (synthetic saturated fatty acid glycidyl ester, trade name of Schiel Chemical Co., Ltd.), AOE (trade name, Daicel Chemical Co., Ltd.) , α-olefin glycidyl ester), etc. may be combined as necessary. The oil-modified alkyd resin in the present invention has an oil length of
It is said to be 25 to 80%, and other components include polybasic acids, polyhydric alcohols, and other modifying components as necessary. Polybasic acids include maleic anhydride, fumaric acid, itaconic acid, malonic acid, phthalic anhydride, isophthalic acid, terephthalic acid, dimethylol terephthalic acid, tetrahydrophthalic anhydride, trimellitic acid, pyromellitic acid, 3,6-
Endomethylenetetrahydrophthalic anhydride, glutaric acid, adipic acid, sebacic acid, etc. are used. Polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, neopentyl glycol, 1,6-hexane glycol, 1,3-butanediol, 1,
4-cyclohexanediol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, hydrogenated bisphenol A, polybutadiene glycol, and the like are used. Other modifying components that may be used as necessary include, for example, epoxy resins, phenolic resins, ketone resins, petroleum resins, benzoic acid, and monobasic acids such as paratertiary butylbenzoic acid. There are no particular limitations on the method for producing the oil-modified alkyd resin. The allyl-alkoxy compound of hexamethylolmelamine used in the present invention is a known compound, for example, hexamethylolmelamine is mixed with allyl alcohol having 1 to 4 carbon atoms in the presence of an acid catalyst.
After obtaining a hexamethylolmelamine resin by simultaneously reacting with a monohydric alcohol or alkoxylating a part or all of the methylol groups of hexamethylolmelamine with a monohydric alcohol having 1 to 4 carbon atoms, the resin is further reacted with an acid. It can be obtained by substituting a part of an alkoxy group with allyl alcohol in the presence of a catalyst. After the above reaction is completed, it is preferable to neutralize the acid catalyst with caustic soda and further distill off unreacted allyl alcohol and alcohol components generated by substitution to obtain a transparent, slightly viscous resin. . The allyl-alkoxy compound of hexamethylolmelamine must have at least one allyl group. The allyl group of the allyl-alkoxy compound of hexamethylol melamine, when mixed with the above oil-modified alkyd resin, plays the role of absorbing oxygen and performing oxidative polymerization similarly to the oil-modified alkyd resin, and the alkoxy group also acts as It improves the compatibility of oil-modified alkyd resins, and at the same time improves the dispersibility of pigments in paint systems that use pigment components such as talc, titanium white, carbon black, and cyanine blue. Gloss is noticeably improved. In addition, hexamethylolmelamine in which all the methylol groups are replaced with allyl groups has increased oxygen absorption (oxidative polymerizability) when mixed with oil-modified alkyd resin, but its compatibility with oil-modified alkyd resin is The dry paint film tends to lose its transparency and gloss, and the surface of the paint film tends to take on an orange peel appearance. The above oil-modified alkyd resin is adjusted to have an oil length of 25 to 80%. If it is less than 25%, the paint film after adding a metal dryer tends to become dry to the touch, but because the crosslinking density of the paint film due to the oxidative polymerization reaction is low, the base paint film may be damaged especially when repainting the paint film. It exhibits a lifting phenomenon, and also tends to have poor solvent resistance, alkali resistance, etc. In addition, in order to reduce the viscosity when the oil length is less than 25%, it is necessary to use many raw materials that give a linear molecular structure, such as adipic acid and ethylene glycol. The balance of the oxidative polymerization reaction due to the double bond becomes unbalanced, and the performance of the coating film when dried at room temperature is completely reduced. In addition, when the oil length exceeds 80%, the molecular structure of the alkyd resin is mostly occupied by the oil component, so the molecular weight of the alkyd resin does not increase, and the secondary transition temperature of the resin becomes low, making it slow to dry to the touch. Furthermore, due to the imbalance between surface hardening and internal hardening of the coating film, water resistance, chemical resistance, etc. are reduced, and hardness, stain resistance, etc. are also poor. In addition, for the above-mentioned oil-modified alkyd resin, an oil having oxidative polymerizability with an iodine value of 40 or more is used in order to impart oxidative polymerizability.
If it is less than this, the oxidative polymerizability of the resulting resin composition will be low and a sufficiently cured coating film will not be obtained, so that the lifting phenomenon, solvent resistance, and chemical resistance will tend to be particularly poor during repainting. Further, the oil-modified alkyd resin has a viscosity of 0.5 to 13.0 poise (at 25°C) measured by the Gardner method when diluted with xylene to a solid content of 60% by weight.
If it is less than 0.5 poise, the molecular weight of the alkyd resin is small and drying is slow, resulting in poor water resistance and adhesion of the cured coating film. On the other hand, if it exceeds 13.0 poise, the drying properties and the water resistance and adhesion of the coating film will be improved, but it will be difficult to obtain a coating with a high solid content and low viscosity. In addition, the acid value of the above oil-modified alkyd resin is 3 to 30.
It is. A coating film using an alkyd resin with an acid value of less than 3 has poor adhesion to the material. If the acid value exceeds 30, the coating film performance after curing will be particularly poor in water resistance. The above oil-modified alkyd resin is in the range of 97 to 50 parts by weight, preferably 95 to 70 parts by weight, and the allyl-alkoxy compound of hexamethylolmelamine is in the range of 3 to 50 parts by weight.
Parts by weight, preferably in the range from 5 to 30 parts by weight, are used in amounts such that the total amount is 100 parts by weight. The amount used is appropriately selected within this range depending on the allyl group content of the allyl-alkoxy compound of hexamethylolmelamine and the constituent components of the oil-modified alkyd resin. If the amount of the allyl-alkoxy compound of hexamethylolmelamine used exceeds the above range, the pigment dispersibility will be good and a coating with high solids content and low viscosity will be obtained, but the coating film after curing will have a relatively low molecular weight. , water resistance and chemical resistance are reduced. Conversely, if the amount used is less than the above range, the pigment dispersibility effect will be significantly reduced, making it difficult to obtain a paint with a high solids content. As the diluting solvent used as necessary in the present invention, solvents such as aliphatics, esters, mineral oils, aromatics, alcohols, and ketones are used. Solvents such as aliphatic, aromatic, and mineral oils are preferred from the viewpoint of painting workability such as repaintability and brushability when drying at room temperature.
200 and 310 (manufactured by Maruzen Sekiyu Co., Ltd.) Single or mixed solvents such as xylol, triol, and mineral spirits are used. Furthermore, when the purpose is to lower the viscosity, it is also possible to use ketones and ester solvents such as methyl ethyl ketone and ethyl acetate. When using the oxidatively polymerizable modified alkyd resin composition of the present invention, naphthenate or octenate of metals such as cobalt, manganese, zirconium, calcium, lead, and zinc is added as a catalyst to promote the oxidative polymerization reaction in the coating film. used. Cobalt, manganese, zirconium, etc. in these catalysts promote oxidative polymerization on the surface of the coating film, and cause calcium,
Lead, zinc, etc. are used as promoters and contribute to internal hardening of the coating film. Generally, these metals are used in combination with those that have a large surface hardening effect on the coating film and those that contribute to internal hardening. Further, even if these metals are used in large amounts, they do not necessarily promote the oxidative polymerization reaction. A stronger coating can be obtained by ensuring that the surface and interior of the coating are cured as uniformly and in a well-balanced manner. Therefore, the type and amount of these metals added vary depending on the use and the properties of the resin, but a practical amount of metal is 0.01 to 5.0% by weight based on the solid content of the resin. If it is less than 0.01% by weight, it will take a long time to dry, so coating workability will not be improved, and if it exceeds 5.0% by weight, the oxidative polymerization reaction will not be particularly promoted, and the uneven drying of the coating will result in poor water resistance and adhesion. Sexuality decreases,
Furthermore, it tends to worsen the storage stability of the paint. Furthermore, as a treatment method for further improving the coating film performance of the oxidatively polymerizable modified alkyd resin composition for paints of the present invention, the coating film is further strengthened by combining it with a urethane prepolymer or with nitrified cotton, salt rubber, etc. Drying performance can be improved. The oxidatively polymerizable modified alkyd resin composition for paints according to the present invention can be made to have high solidity and low viscosity, and the performance of the resulting coating film is also excellent. This will be explained below using Examples and Comparative Examples. Parts refer to parts by weight. 1 Production example of oil-modified alkyd resin 1 Cardilla E (trade name of Ciel Chemical Co., Ltd., glycidyl ester of synthetic saturated fatty acids) 120 parts, linseed oil fatty acid (iodine value 172) 461.6 parts, paratertiary butylbenzoic acid 333.8 parts, anhydrous 375.8 parts of phthalic acid,
226.5 parts of pentaerythritol, 88.5 parts of ethylene glycol, and a small amount of xylene for circulation
Place in a four-necked flask and pass inert gas through it.
The mixture was heated at 180°C for 1 hour, then raised to 200°C, and heated at the same temperature until the viscosity according to the Gardner method reached 3.5 poise (25°C) when diluted with xylene to a solid content of 60% by weight. After the reaction is complete, dissolve in xylol,
The xylol content was adjusted to 40% by weight. The obtained oil-modified alkyd resin (1) had a solid content of 60.8% by weight, a viscosity of 3.7 poise (25°C) by the Gardner method,
It showed an acid value of 8.4 and a color number (Gardna) of 4. Production example 2 Cardilla E 150 parts, soybean oil fatty acid (iodine value
125) 576.9 parts, paratersiabutylbenzoic acid
170.0 parts of phthalic anhydride, 418.4 parts of phthalic anhydride, 252.0 parts of pentaerythritol, 40.5 parts of ethylene glycol, and a small amount of circulating xylol were placed in a four-necked flask, and the esterification reaction was carried out according to the same heating schedule as in Example 1. . The end point was when the viscosity reached 2.1 poise (25°C) according to the Gardner method when diluted with xylol to a solid content of 60% by weight. After the reaction was completed, it was dissolved in xylene and the xylene content was adjusted to 30% by weight. The obtained oil-modified alkyd resin (2) had a heating residue of 69.8% by weight, a viscosity of 6.3 poise,
It showed an acid value of 7.9 and a color number (Gardna) of 3. Production example 3 Cardilla E 195 parts, soybean oil fatty acid 750 parts, paratersia butylbenzoic acid 83.4 parts, phthalic anhydride
336.5 parts of pentaerythritol, 232.5 parts of pentaerythritol, and a small amount of circulating xylene were placed in a four-necked flask (No. 2) and heated at 180°C for 1 hour while passing inert gas, then heated to 200°C for 1 hour, and further heated to 220°C. At the same temperature, the viscosity according to the Gardner method when diluted with xylene to a solid content of 60% by weight was 0.85 poise (25
The point at which the temperature reached ℃) was defined as the end point. After the reaction is completed, dissolve in mineral spirits and make 30% of mineral spirits.
It was adjusted to be % by weight. The obtained oil-modified alkyd resin (3) had a heating residue of 70.6% by weight, a viscosity of 7.2 poise (25°C) according to the Gardner method, an acid value of 10.2, and a color number (Gardner) of 3. 2 Production of allyl-alkoxy compound of hexamethylolmelamine 378 parts of melamine, 114 parts of paraformaldehyde with a purity of 80%, and 960 parts of methanol were placed in a four-necked flask from 2, heated to 60°C, and after uniformly dissolving, a small amount of caustic soda was added. was added to adjust the pH to 8.5, and then heated to 30% at the same temperature.
When the mixture was kept warm for several minutes and immediately cooled to below 40°C, hexamethylolmelamine crystallized and precipitated. Remove the crystals and add 960 parts of fresh methanol again.
The temperature was raised to 60°C, a small amount of hydrochloric acid was added to adjust the pH to 3.2, and after keeping at the same temperature for 3 hours, the pressure inside the flask was reduced and methanol was distilled to obtain a semi-solid solution of hexamethoxymelamine resin. . Place 800 parts of hexamethoxymelamine resin and 2000 parts of allyl alcohol in a four-necked flask,
A small amount of nitric acid was added to adjust the pH to 1.5. 2 at 60℃
After keeping warm for an hour, cool and add a small amount of caustic soda to pH.
Adjusted to 7.5. The temperature was raised to 100°C again, and free allyl alcohol was removed under reduced pressure. The obtained resin had a solid content of 99.8% by weight, a viscosity of 8.7 poise (25°C) according to the Gardner method, and a color number of 1 to 2 (Gardner). Next, Table 1 shows the coating film performance of the coating material in which the oil-modified alkyd resin obtained above was combined with the allyl-methoxy compound of hexamethylolmelamine. The paint was prepared according to the formulation shown below, kneaded four times with a triple roll, and then diluted with xylol or mineral spirits in a #4 food cup for 30 seconds (25°C). This was tested as a sample. 1 Oxidation-polymerizable modified alkyd resin composition (converted to solid content of 100% by weight) in paint 100 parts Titanium white (rutile) (manufactured by Sakai Chemical Co., Ltd.) 100 parts 5% Co-naphthenate (manufactured by Dainippon Ink Chemical Co., Ltd.) 1.0 part 15% Pb-Naphthenate (manufactured by Dainippon Ink Chemical Co., Ltd.) 3.3 Part 2 Paint film test method (1) Drying property Even if you apply the paint on a glass plate with a bar coater #40 and press it with your finger, the paint will not stick to your finger. The time it takes to feel dry to the touch is defined as the time it takes to dry to the touch. Similarly, the time taken to harden the adhesive with a finger until it no longer felt sticky was defined as semi-curing and drying. Drying conditions were a constant temperature room at 20°C and 65% relative humidity. (2) Repaintability (recoatability) Paint is applied onto a tin plate using a bar coater #40, and after being left at room temperature (20°C, relative humidity 65%), the same paint is flow-coated at predetermined intervals to coat the base plate. The time until the paint film was no longer damaged was measured. (3) General coating performance Paint is applied to ponderite treated steel plate (0.8t×70mm×
150mm), spray paint (film thickness 40-60μ),
After being left at room temperature (20°C, relative humidity 65%) for 5 days, it was subjected to the following test. Gloss: Reflectance at 60° was measured using a specular reflection photometer. Painted surface condition: The painted surface condition was visually observed. Pencil hardness: Using a Mitsubishi Uni-Pencil, the hardness was measured when the painted surface was strongly pressed at 45 degrees and the paint film broke. Erichsen: Using an Erichsen measuring machine, the length (mm) of extrusion from the back of the paint film until the paint film breaks was measured. Impact strength: using Dupont impact machine, 1/2 inch,
Weights with loads of 500 g and 1000 g were dropped from predetermined heights, and the height at which the coating film was torn was measured. Water resistance: 10 at room temperature (18-22℃) using city tap water
After soaking for a day, the whitening of the coating film and the state of blisters were observed. Hot water resistance: It was immersed in city tap water at 40°C for 5 days and the whitening of the coating film and the state of blisters were observed. Moisture resistance: The condition of blisters on the coating film was observed after being placed in a blister box at 50°C and 98% relative humidity for 3 days. Boiling water resistance: The paint was immersed in boiling city tap water for 30 minutes and the state of whitening of the paint film was observed. NaOH resistance: Approximately 1 c.c. of 5% NaOH aqueous solution is applied to the coating film.
Drop it and leave it at room temperature (18-22
℃) for one day, and then wiped with absorbent cotton to observe yellowing, glossiness, and blistering of the coating film. H ₂ SO ₄ resistance: Approximately 1 c.c. of 5% H ₂ SO ₄ aqueous solution is applied to the coating film.
Drop it and leave it at room temperature (18-22
℃) for one day, and then wiped with absorbent cotton to observe yellowing, glossiness, and blistering of the coating film. Gasoline resistance: manufactured by Idemitsu Chemical Co., Ltd., immersed in gasoline (regular type) for one day and observed for softening of the coating film and the state of blisters. Magic contamination: A red magic marker made by Uchida Yoko was applied to the paint film and left at room temperature for 1 hour, then wiped off with absorbent cotton soaked in butanol and observed for magic stains. Corrosion resistance: Make diagonal cuts in the coating film with a knife and spray with 5% NaCl in a salt water sprayer at 35°C.
After leaving it for a day, the water droplets on the paint film were wiped off with absorbent cotton, and Sellotape was placed on top of the cut, which was then removed and the peeling of the cut part was examined. The width (mm) of the paint film peeled off by cellophane tape was shown as the rust width. In the table, ◎ indicates no abnormality, 〇 indicates almost no abnormality,
△ indicates that there is a slight abnormality, and × indicates that there is an abnormality.

【table】

[Table] As is clear from the above experimental results, the paint using the oxidation-polymerizable modified alkyd resin composition for painting according to the present invention has a high solid content, low viscosity, and has good film performance, especially drying properties. , water resistance, alkali resistance and corrosion resistance are significantly improved. The resin composition of the present invention has great practical effects in terms of countermeasures regarding organic solvent regulations, efficiency of painting workability, and coating film performance.

Claims (1)

[Scope of Claims] 1 (A) An oil component having an iodine value of 40 or more and having oxidative polymerizability is made to have an oil length of 25 to 80%, and a viscosity of 0.5 to 13.0 poise (25°C, 60% by weight in xylol). % and measured by Gardner method), acid value 3
-30 oil-modified alkyd resin in the range of 97 to 50 parts by weight and (B) the allyl-alkoxy compound of hexamethylolmelamine in the range of 3 to 50 parts by weight, so that the total amount of (A) and (B) is 100 parts by weight. (C) an oxidatively polymerizable modified alkyd resin composition for paint, which optionally contains a diluting solvent;