JP2008189934A - Chipping-resistant coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chipping-resistant coating composition having various advantages such as absence of hydrogen chloride generation by incineration of a used vehicle owing to absence of a vinyl chloride resin and little load to the environment owing to a little amount of solvent generation at the time of spray operation. <P>SOLUTION: The chipping-resistant coating composition comprises a blocked urethane compound (A), which reproduces an isocyanate by heating, a compound (B) containing a hydroxy group and/or an amino group reactive with the compound (A), and a filler (C). The equivalent ratio of the compound (A) and the compound (B) is 0.5-2.0. The compound (A) is a blocked urethane of a 4,4'-diisocyanate diphenyl methane as a fine powder of a particle size of 0.01-50 μm and a melting point of 100-160°C, obtained by reaction with a blocking agent with a dissociation temperature of 100-140°C. The heating temperature for reproducing the isocyanate in the compound (A) is 100°C or higher. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a chipping resistant coating applied to automobiles for the purpose of rust prevention and soundproofing, and more particularly to a chipping resistant coating composition that does not cause a pollution problem due to generation of hydrogen chloride at the time of incineration of used vehicles.

  Chipping-resistant paint is applied to the underside of automobiles, side sills, whale tanks, front apron, tire houses, etc. for the purpose of rust prevention and soundproofing, but this paint has conventionally been a so-called vinyl chloride sol containing a vinyl chloride resin. Mainly paint.

  In recent years, pollution problems caused by the generation of hydrogen chloride at the time of incineration of used vehicles have been highlighted, and the development of anti-chipping coatings that do not contain vinyl chloride resin has been urgently required.

  As one means, water-based anti-chipping paints as seen in Patent Documents 1 and 2 and acrylic sol-type anti-chipping paints based on acrylic resin as shown in Patent Documents 3 and 4 were developed. It was done.

  However, for water-based paints, all of the painting equipment used to introduce them must be replaced with rust-free equipment such as stainless steel, which requires a great investment. On the other hand, the acrylic sol paint has already been put into practical use, but the strength of the cured film is low and it is difficult to make it thin.

In addition, a one-pack type chipping-resistant paint mainly composed of a urethane resin has been developed. However, a large amount of solvent is contained for spray coating, which is not preferable for safety and hygiene.
JP-A-5-163462 JP-A-6-157938 JP-A-7-233299 JP-A-8-295850

  The present invention has been made in view of the above-mentioned problems, and the present inventors have conducted intensive research in order to provide a paint that can reduce pollution problems and safety and health problems and that can use conventional coating equipment as it is. As a result, by using fine powder blocked urethane, the present inventors have completed the present invention by finding a paint that can be easily applied by spraying even with a small amount of solvent and that does not generate hydrogen chloride during incineration.

  The present invention eliminates the generation of hydrogen chloride due to incineration of used vehicles because it does not contain vinyl chloride resin, and has a variety of advantages such as less environmental load due to less solvent generation during spraying. An object of the present invention is to provide a paint composition.

  The chipping-resistant coating composition of the present invention includes a blocked urethane compound (A) that regenerates isocyanate by heating, a compound (B) containing a hydroxyl group and / or an amino group that reacts with the compound (A), and a filler. A coating composition for chipping resistance containing (C), wherein the equivalent ratio of the compound (A) to the compound (B) is 0.5 to 2.0, and the compound (A) is a blocking agent. Is a blocked urethane of diphenylmethane 4,4′-diisocyanate obtained by reacting with the compound, wherein the dissociation temperature of the blocking agent is 100 ° C. to 140 ° C., and heating for regenerating isocyanate in the compound (A) The temperature is 100 ° C. or higher, and the compound (A) is a fine powder having a melting point of 100 ° C. to 160 ° C. and a particle size of 0.01 μm to 50 μm, and the compound (B) Is a hydroxyl group-containing polyether polyol having a molecular weight of 300 to 3000 and having 2 or more functional groups, and / or a 1 to 3 functional group-containing polyamine having a molecular weight of 200 to 6000.

  The coating composition for chipping resistance of the present invention does not contain vinyl chloride resin, so that generation of hydrogen chloride due to incineration of used vehicles is eliminated, and the amount of solvent generated during spraying is small, so the burden on the environment is small. Has various advantages.

  The chipping-resistant coating composition of the present invention comprises a blocked urethane compound (A) that regenerates isocyanate by heating, a compound (B) containing a hydroxyl group and / or amino group that reacts with the compound (A), and a filler ( C) and a coating composition for chipping resistance, wherein the equivalent ratio of the compound (A) to the compound (B) is 0.5 to 2.0. The equivalent ratio is more preferably 0.8 to 1.2. When the equivalent ratio is less than 0.5, curing is poor. Moreover, when an equivalent ratio exceeds 2.0, a compound (B) becomes excess and the physical property of hardened | cured material falls.

  The heating temperature for regenerating isocyanate in the compound (A) is preferably 100 ° C. or higher, and the compound (A) is preferably a fine powder having a melting point of 100 ° C. to 160 ° C. and a particle size of 50 μm or less. If the melting point of the compound (A) does not reach 100 ° C., defects such as fusion occur during coating production and dispersion failure occurs, or fusion occurs during storage of the finished coating, resulting in a viscosity increase. Further, when the melting point of the compound (A) exceeds 160 ° C., it is melted when baked in a normal intermediate coating furnace (130 to 150 ° C., 15 to 40 minutes) or a top coating furnace (130 to 150 ° C., 15 to 40 minutes). Defects occur such as poor reaction and insufficient surface of the cured film.

  Further, when the particle diameter of the compound (A) exceeds 50 μm, problems such as chip clogging occur when the finished paint is sprayed with airless spray. Furthermore, when this particle size exceeds 50 μm, melting failure occurs when baked in a normal intermediate coating furnace (130 to 150 ° C., 15 to 40 minutes) or top coating furnace (130 to 150 ° C., 15 to 40 minutes). As a result, problems such as insufficient reaction and uneven surface of the cured film occur. The lower limit of the particle size of the compound (A) is not particularly limited, but for example, a particle size of about 0.01 μm can be used.

  Suitable starting components of the heat-regenerated blocked urethane compound (A) used in the present invention are di- or polyisocyanates and mixtures thereof. However, these components require that the blocked urethane compound (A) obtained by reacting with the blocking agent is solid at room temperature.

  Suitable di- or polyisocyanates include aliphatic, cycloaliphatic, araliphatic and preferably heterocyclic polyisocyanates such as those found in JP-A-7-278257, such as aniline / formaldehyde condensation followed by phosgene. And polymethylene polyisocyanate obtained by conversion. Polyisocyanates containing carbodiimide groups, polyisocyanates containing allophanate groups, polyisocyanates containing isocyanurate groups, polyisocyanates containing urethane and / or urea groups, polyisocyanates containing acylated urea groups, polyisocyanates containing biuret groups, Polyisocyanates produced by polymerization reactions, polyisocyanates containing ester groups, preferably diisocyanates containing uretdione groups and diisocyanates containing urea groups are also suitable.

  Specific examples include the following. p-xylylene diisocyanate, 1,5-diisocyanatomethylnaphthalene, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methylbenzene 2,5-diisocyanate, 1,3 dimethylbenzene 4,6-diisocyanate 1,4-dimethylbenzene 2,5-diisocyanate, 1-nitrobenzene 2,5-diisocyanate, 1-methoxybenzene 2,4-diisocyanate, 1-methoxybenzene 2,5-diisocyanate, 1,3-dimethoxybenzene 4,6 -Diisocyanate, azobenzene 4,4'-diisocyanate, diphenyl ether 4,4'-diisocyanate, diphenylmethane 4,4'-diisocyanate, diphenyldimethylmethane 4,4'-diisocyanate, naphthalene 1 5-diisocyanate, 3,3′-dimethylbiphenyl 4,4′-diisocyanate, diphenyl disulfide 4,4′-diisocyanate, diphenylsulfone 4,4′-diisocyanate, 1-methylbenzene 2,4,6-triisocyanate, 1 , 3,5-trimethylbenzene 2,4,6-triisocyanate, triphenylmethane 4,4 ′, 4 ″ -triisocyanate, 4,4′-diisocyanato- (1,2) -diphenylethane, dimer 1 -Methyl-2,4-phenylene diisocyanate, dimer 1-isopropyl-2,4-phenylene diisocyanate, dimer 2,4'-diisocyanatodiphenyl sulfide, 3,3'-diisocyanato-4,4'- Dimethyl-N, N′-diphenylurea, 3,3′-diisocyanato-2,2 -Dimethyl-N, N'-diphenylurea, 3,3'-diisocyanato-2,4'-dimethyl-N, N'-diphenylurea, N, N'-bis [4 (4-isocyanatophenylmethyl) phenyl ] Urea, N, N′-bis [4 (2-isocyanatophenylmethyl) phenyl] urea.

  Examples of the blocking agent used to obtain the blocked urethane compound (A) include oxime compounds (acetooxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, etc.), lactams (ε-caprolactam, etc.), active methylene compounds ( Diethyl malonate, acetylacetone, ethyl acetoacetate, etc.), phenols (phenol, m-cresol, etc.), alcohols (methanol, ethanol, n-butanol, etc.), hydroxyl group-containing ethers (methylcellsolve, butylcellsolve, etc.), Hydroxyl-containing esters (such as methyl lactate and amyl lactate), mercaptans (such as butyl mercaptan and hexyl mercaptan), acid amides (such as acetanilide, acrylic amide, and dimer amide), imidazoles (imida) Lumpur, such as 2-ethyl imidazole), imides (succinimide, phthalic acid imide), amines (such as dicyclohexylamine), and mixtures of two or more thereof.

  Of these, oxime compounds, phenols and amines are preferred, and methyl ethyl ketoxime, phenol and dicyclohexylamine are particularly preferred. Since these dissociation temperatures are relatively low at 100 ° C. to 140 ° C., the reaction proceeds sufficiently even when applied to automobiles as anti-chipping paints.

  As the compound (B), it is preferable to use a hydroxyl group-containing polyether polyol or polyester polyol having a molecular weight of 300 to 3000 and having 2 or more functional groups, and / or a 1-3 functional group-containing polyamine having a molecular weight of 200 to 6000. When the molecular weight of the compound (B) of a hydroxyl group-containing polyether polyol or polyester polyol having two or more functional groups does not reach 300, the physical properties of the cured product are lowered. On the other hand, when the molecular weight exceeds 3000, the viscosity becomes high, which hinders the spraying workability by airless spray. Similarly, the physical property of hardened | cured material falls that the molecular weight of the compound (B) of 1-3 functional group containing polyamine is less than 200. On the other hand, when the molecular weight exceeds 6000, the viscosity becomes high, which impairs the spraying workability by airless spray.

  The polyether polyol used in the present invention is selected from known ones having 2 or more, preferably 2 to 6 hydroxyl groups.

  These polyether polyols include ethylene glycol, propylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, hexanetriol, polytetramethylene ether glycol, pentaerythritol, sorbitol, shoecloth, polyethylene glycol, polypropylene glycol, Examples include polytetramethylene glycol and tertiary nitrogen-containing polyol.

  Among these, a tertiary nitrogen-containing polyol is preferable, and a molecular weight of 300 to 3000 is preferable. When this molecular weight does not reach 300, the physical properties of the cured product are lowered. On the other hand, when the molecular weight exceeds 3000, the viscosity becomes high, which hinders workability.

  Examples of polyester polyols include polycarboxylic acids (for example, aliphatic polycarboxylic acids such as adipic acid, maleic acid, and dimerized linoleic acid, and aromatic polycarboxylic acids such as phthalic acid) as disclosed in JP-B-64-11232. Terminal hydroxyl group-containing polyester polyol with low molecular polyol or polyether polyol, polycaprolactone polyol such as initiator [glycol (ethylene glycol etc.), triol etc.) as a base and caprolactone (ε-caprolactone, α-methyl-ε-) And a polyol obtained by addition polymerization of caprolactone and the like in the presence of a catalyst such as an organometallic compound.

  Examples of the polyamine that can be used in the present invention include known polyalkylene polyamines and polyoxyalkylene amines.

  Specific examples include the following. Polyethylenetetramine (diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, decaethyleneundecamine, etc.), polypropylene polyamine (dipropylenetriamine, tripropylenetetramine, nonapropylenedecamine, etc.), polybutylene polyamine (dibutylene) Triamine etc.), poly (pentamethylene) polyamine [bis (pentamethylene) triamine etc.], poly (hexamethylene) polyamine [bis (hexamethylene) triamine etc.], polyoxyethyleneamine, polyoxypropyleneamine.

  Of these, polyether polyamine is preferred, and has a molecular weight of about 200 to 6000, preferably 400 to 5000, and more preferably 1000 to 5000. If the molecular weight is less than 200, the physical properties of the cured product are lowered. On the other hand, when the molecular weight exceeds 6000, the viscosity becomes high and the workability is hindered.

  The chipping-resistant coating composition of the present invention contains the filler (C) as an essential component and is used in an amount of 5 to 50% by weight, preferably 10 to 30% by weight, based on the total weight of the coating. If the amount used exceeds 50% by weight, the coating strength after the coating is cured is weak and the antirust function as a chipping resistant coating cannot be performed. On the other hand, if it is less than 5% by weight, workability, in particular, sagging property is deteriorated, and the prescribed coating thickness cannot be obtained.

  Generally, examples of the filler include talc, clay, kaolin, heavy calcium carbonate, light calcium carbonate, barium sulfate, silica, titanium oxide, aluminum silicate, magnesium oxide, and zinc oxide. Can be used in combination.

  The composition of the present invention is optionally composed of known acrylic resins, such as polymethyl methacrylate having a molecular weight of 5 to 2 million and methyl methacrylate, ethyl methacrylate, normal butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, cyclohexyl methacrylate, ethyl hexyl methacrylate. Two or more kinds of copolymers and the like that are selected can be appropriately used alone or in combination of two or more.

  The compositions of the present invention optionally have aliphatic or aromatic bonds with known plasticizers such as phthalic acid, trimellitic acid, adipic acid, sebacic acid, azelaic acid, phosphoric acid, sulfonic acid, oleic acid and stearic acid. A compound containing an OH group, for example, an ester with an alcohol or phenol can be appropriately used alone or in combination of two or more.

  Specific examples of suitable esters include benzyl butyl phthalate, bis- (2-ethylhexyl) phthalate, di-isononyl phthalate, tris- (2-ethylhexyl) trimellitate, bis- (2-ethylhexyl) adipate, tricresyl phosphate , Diphenyloctyl phosphate, tris- (2-ethylhexyl) phosphate, alkyl-sulfonic acid phenyl ester, and the like.

  The composition of the present invention may optionally contain known additives such as inorganic flame retardants (aluminum hydroxide, magnesium hydroxide), hygroscopic agents (calcium oxide, zeolite, silane), colorants (dyes, pigments), lightening materials. (Glass balloon, ceramic balloon, shirasu balloon, resin balloon), organic foaming agent (azodicarbonamide, 4,4′-oxbisbenzenesulfonylhydrazide, N, N′-dinitrosopentamethylenetetramine, hydrazinecarbonamide, azo Bisisobutyronitrile), heat-expandable microballoons, viscosity modifiers (surfactants, coupling agents, aliphatic hydrocarbons) can be used.

  The composition of this invention can be manufactured by a well-known method. For example, it can be obtained by using a normal mixing apparatus, a vertical biaxial mixer, a planetary mixer, a ball mill, a roll mill, a biaxial blender, a kneader, a vertical high-speed stirrer, and the like to obtain a mixed paint.

  The chipping-resistant coating composition of the present invention can be used as it is without any change in the conventional coating apparatus and coating conditions of an automobile coating line. Subsequent baking is also possible under the same conditions as before. That is, it is applied to a predetermined film thickness (0.2 mm to 2 mm) with a normal airless spray apparatus, and then the intermediate coating furnace (130 to 150 ° C., 15 to 40 minutes), the top coating furnace (130 to 150 ° C., 15 A cured coating film that is heated by passing through (about 40 minutes) and does not impair the appearance quality such as dripping, cracking, swelling and shrinkage can be obtained.

  The present invention will be described more specifically with reference to the following examples. However, it is needless to say that these examples are shown by way of illustration and should not be construed in a limited manner. In addition, the part in the Example and comparative example which are mentioned below shows a weight part.

(Example 1)
Blocked urethane of diphenylmethane 4,4'-diisocyanate obtained by reaction with methyl ethyl ketoxime 10 parts Polyoxypropylene triamine (molecular weight: 5000) 50 parts Methyl methacrylate-butyl methacrylate copolymer resin (molecular weight: 800,000) 20 parts carbonic acid Calcium 50 parts Calcium oxide 10 parts Diisononyl phthalate (DINP) 45 parts Aliphatic hydrocarbon (boiling range: 180-230 ° C.) 15 parts were uniformly stirred and dispersed to prepare a chipping resistant coating composition.

  This coating composition was sprayed onto an electrodeposited steel plate using an airless spray pump so that the thickness became 0.4 mm. The sprayability was good, the pattern width was wide enough, and there was little mist, allowing uniform application. When the coated electrodeposition coated steel sheet was held in a thermostatic bath at 130 ° C. for 20 minutes and baked, a surface film having a good appearance was obtained.

  Next, the performance of this coating composition was tested for the items shown in Table 1, and the results are shown in Table 1. As shown in Table 1, the viscosity is 70 Pa · s, sprayability is good, solid content is 93%, sagging property is 0 mm, adhesion is good, and chipping resistance is 50 kg / 0.4 mm. It was found that the coating composition had excellent chipping resistance.

(Example 2)
The polyoxypropylene triamine of Example 1 was replaced with 20 parts of polyoxyethylene-added tertiary nitrogen-containing polyfunctional polyol ("EDP-450" manufactured by Asahi Denka Kogyo Co., Ltd.), 55 parts of DINP, aliphatic hydrocarbon (boiling point) (Range: 180-230 ° C.) was 20 parts. Otherwise, the same procedure as in Example 1 was conducted to obtain a chipping resistant coating composition. The performance was also evaluated in the same manner as in Example 1 and shown in Table 1. As is apparent from Table 1, although it was slightly lower in performance than the coating composition of Example 1, it was confirmed that the coating composition had good chipping resistance as a comprehensive evaluation.

(Example 3)
A chipping-resistant coating composition was obtained in the same manner as in Example 1 except that the polyoxypropylene triamine of Example 1 was replaced with polyoxypropylene diamine (molecular weight: 2000). The performance was also evaluated in the same manner as in Example 1 and shown in Table 1. As is clear from Table 1, it was found that the coating composition had good chipping resistance as a comprehensive evaluation, although the performance was slightly lower than that of the coating composition of Example 1.

(Comparative Example 1)
Instead of the blocked urethane obtained in Example 1 by reacting the adduct of tolylene diisocyanate of polyoxypropylene glycol with methyl ethyl ketoxime, 25 aliphatic hydrocarbons (boiling range: 180 to 230 ° C.) were used. To the department. Otherwise, the same procedure as in Example 1 was conducted to obtain a chipping resistant coating composition. The performance was also evaluated in the same manner as in Example 1 and shown in Table 1. As shown in Table 1, although performances other than sprayability were good, the sprayability was extremely poor, and thus it was found that the chipping-resistant coating composition was poor as a comprehensive evaluation.

(Comparative Example 2)
The chipping-resistant coating composition was obtained in the same manner as in Example 1 except that the blocked urethane of Example 1 was replaced with a blocked urethane of diphenylmethane 4,4′-diisocyanate obtained by reacting ε-caprolactam. . The performance was also evaluated in the same manner as in Example 1 and shown in Table 1. As shown in Table 1, although the performance other than the chipping resistance is good, the chipping resistance is extremely poor. Therefore, it was found that the overall evaluation is a poor chipping resistance coating composition.

The test methods in Table 1 are as follows.
1. Viscosity BH viscometer, rotor no. 7, 20 rpm.

2. Spraying When using an airless pump (King type) manufactured by Nippon Gray Co., Ltd. with a pre-gun pressure of 9.8 MPa and applying with nozzle # 527, a good pattern width is obtained, and there is little tail or mist, and there is no uneven coating.

The evaluation of sprayability is as follows.
○: Good pattern width, no tail, no mist, no coating unevenness.
Δ: Pattern width is slightly narrow, tail, mist is slightly present.
X: The pattern does not widen, and the coating unevenness cannot be applied uniformly.

3. The mass of an aluminum sheet having a solid content of 40 × 40 × 0.2 mm is measured, and a sample is applied 30 × 30 × 0.4 mm and weighed. Next, it is heated at 140 ° C. for 30 minutes in a thermostatic bath, and the mass is measured after cooling in a desiccator. The solid content is calculated by the following formula (1).
Solid content (%) = 100 × (W ₃ −W ₁ ) / (W ₂ −W ₁ ) (1)
In formula (1), W ₁ : mass (mg) of aluminum sheet, W ₂ : mass before heating aluminum sheet and sample (mg), W ₃ : mass after heating aluminum sheet and sample (mg).

4). Sagging property The sample was applied to a 150 x 70 x 0.8 mm electrodeposition coated steel sheet in a semicircular bead shape with a radius of 4 mm x length of 100 mm, left standing at room temperature for 30 minutes, and then placed in a constant temperature bath at 95 ° C. After 8 minutes of heating, take out and measure sagging (mm).

5. Adhesion A sample is applied to the end of an electrodeposited steel sheet of 100 × 25 × 0.8 mm, and a spacer is sandwiched, bonded and fixed so that the thickness of the bonded portion is 3 mm, and baked at 130 ° C. for 20 minutes. After removal, the spacer is removed and the shear adhesive strength is measured at a pulling speed of 50 mm / min.

The evaluation of adhesiveness is as follows.
○: The destruction state is cohesive failure.
Δ: Partially fractured interface.
X: The destruction state is a complete destruction.

6). Chipping resistance A sample is applied to an electrodeposited steel sheet of 150 × 70 × 0.8 mm so as to be 0.4 mm and baked at 130 ° C. for 20 minutes. When the temperature returns to room temperature, the M4 brass nut is dropped from a height of 2 m through a PVC pipe having an inner diameter of 2 cm, and the hole reaching the base of the coating film is continuously dropped. The angle of the test piece is 60 °.

7). Comprehensive evaluation The comprehensive evaluation as a coating composition for chipping resistance is shown. Judgment of comprehensive evaluation is as follows.
○: Excellent.
○ △: Good.
Δ: Can be used.
X: Defect.

Claims (1)

Blocked urethane compound (A) that regenerates isocyanate by heating,
A chipping-resistant coating composition comprising a compound (B) containing a hydroxyl group and / or an amino group that reacts with the compound (A), and a filler (C),
The equivalent ratio of the compound (A) to the compound (B) is 0.5 to 2.0,
The compound (A) is a blocked urethane of diphenylmethane 4,4′-diisocyanate obtained by reacting with a blocking agent, and the dissociation temperature of the blocking agent is 100 ° C. to 140 ° C. The heating temperature for regenerating isocyanate in A) is 100 ° C. or higher, and the compound (A) is a fine powder having a melting point of 100 ° C. to 160 ° C. and a particle size of 0.01 μm to 50 μm,
The compound (B) is a hydroxyl group-containing polyether polyol having a molecular weight of 300 to 3000 and having 2 or more functional groups and / or a 1 to 3 functional group-containing polyamine having a molecular weight of 200 to 6000. object.