JP2003128989A - High-solid coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new high-solid coating composition using a curing agent composition including a low-viscosity polyisocyanate composition with high crosslinking ability. SOLUTION: This high-solid coating composition comprises a main agent polyol comprising a low-molecular weight acrylic polyol or polyester polyol and the polyisocyanate composition which is obtained from an aliphatic diisocyanate and/or alicyclic diisocyanate and has the content of component(s) <=700 in molecular weight of 20-60 mass%, the ratio: weight-average molecular weight/number-average molecular weight of 1.2-5.0, and the ratio: viscosity (mPa.s)/the average number of isocyanate functional groups of <=240.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high solid coating composition using a specific low-molecular-weight base polyol composition and a curing agent composition containing a low-viscosity, high-functionality polyisocyanate composition, and particularly for automobiles. The present invention relates to a high solid coating composition used for applications.

[0002]

2. Description of the Related Art Coating compositions using aliphatic and alicyclic polyisocyanate compositions are excellent in flexibility and weather resistance, particularly acid rain resistance. Widely used as a paint for home appliances. However, in the paint field as well, there is an urgent need to reduce the amount of organic solvents used from the viewpoint of environmental protection against air pollution and resource saving, and paint manufacturers, automobile manufacturers, home appliance manufacturers, etc. are also developing paints that support this. proceeding. As a method of reducing the organic solvent of the coating composition, mainly water-based,
It is known to make powder and high solid. Among them, a dense cross-linked coating film is used for automobiles, especially top coats for automobile exterior parts, and interior / exterior applications where high quality appearance and excellent weather resistance and durability are required. There is a high possibility that a high solid type two-component polyurethane coating material that can form a resin and has a good finished appearance will be widely used.

As the base polyol used in such a high solid coating composition, it has been proposed to use an acrylic polyol or polyester polyol having excellent weather resistance and durability, which has a low molecular weight. For example, Japanese Unexamined Patent Publication (Kokai) No. 5-59326 proposes a top clear paint using a urethane-modified acrylic resin whose molecular weight is suppressed to a low level, and Japanese Patent Laid-Open No. 9-508174 discloses a top clear paint made from a specific polyol and carboxylic acid. An automobile repair paint using a high solid polyester polyol has been proposed. On the other hand, the polyisocyanate composition used for the high solid coating composition is required to have not only a low viscosity but also a high crosslinking ability. Therefore, when a conventionally known low-viscosity polyisocyanate composition using an allophanate body in which two molecules of diisocyanate such as monoalcohol and hexamethylene diisocyanate (hereinafter, HDI) are added, or a uretdione body in which diisocyanate is dimerized is used, Poor curability may occur due to low crosslinking ability.

On the other hand, the conventionally known polyisocyanate composition obtained by converting HDI or the like into an isocyanurate is at least trifunctional, and therefore has a relatively high crosslinking ability, but has a high viscosity, so that it is used for high solids. It is difficult to use as a paint. Japanese Unexamined Patent Publication (Kokai) No. 9-12660 discloses a polyisocyanate composition which is easily dissolved in a low-polarity organic solvent, and an isocyanurate having an allophanate group, which uses a monoalcohol having 6 to 20 carbon atoms and a diol having 4 to 40 carbon atoms as raw materials. A type of polyisocyanate composition has been proposed. However, in a polyisocyanate composition having an isocyanurate structure as a basic structure, it is difficult to obtain a polyisocyanate composition having a high number of functional groups and a low viscosity, because the higher the number of functional groups is, the higher the molecular weight is.

Further, the polyisocyanate compositions obtained by combining an allophanate form of monoalcohol and an isocyanurate form disclosed in JP-A-4-306218, Japanese Patent No. 2610530 and Japanese Patent No. 2670934 have a low viscosity. If this is attempted, the number of functional groups inevitably decreases, and the curability may be insufficient. JP-A-9
No. 216930 discloses a low-viscosity polyisocyanate having a viscosity of 700 mPa.s. polyisocyanate exceeding s and aliphatic (alicyclic) having a viscosity of less than 200 mPas
Triisocyanate mixtures are disclosed. But,
Compared with general polyisocyanates using HDI,
Problems remain in that the aliphatic (alicyclic) triisocyanate is very expensive and that the coating film tends to be hard and brittle.

[0006]

SUMMARY OF THE INVENTION In view of the above situation, the present invention contains a main component polyol having a relatively low molecular weight,
An object of the present invention is to provide a high solid type two-component polyurethane coating composition using a curing agent composition containing a polyisocyanate composition having a low viscosity and an excellent crosslinking ability.

[0007]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have identified a base polyol containing an acrylic polyol or polyester polyol having a relatively low molecular weight, an isocyanate group functional group number, and a molecular weight distribution. It was found that a high solid coating composition using a curing agent composition containing a polyisocyanate composition having an allophanate group set in the conditions can achieve the above object, and based on this, the present invention has been completed. .

That is, the present invention includes 1) (a) a base polyol composition containing an acrylic polyol having a number average molecular weight of 500 to 10,000 or a polyester polyol, and (b) at least an aliphatic diisocyanate or an alicyclic diisocyanate. Using one kind of diisocyanate as a raw material, the content of components having a molecular weight of 700 or less is 20 to 60% by mass, the ratio of the weight average molecular weight to the number average molecular weight is 1.2 to 5.0, and the viscosity of the polyisocyanate composition at 25 ° C. The ratio (unit mPa.s) to the number average functional group number of isocyanate groups is a curing agent composition viscosity (mPa.s) / number average functional group number containing a polyisocyanate composition having an allophanate group represented by the following formula. ≦ 240, 2) High solid coating composition, 2) Non-volatile content at the time of coating is 65 mass% or less In it the above high-solid coating composition, 3) the base resin polyol composition has a number average molecular weight of from 500 to 8
High solid coating composition of 000, 4) the high solid coating composition, wherein the polyisocyanate composition has a molar ratio of allophanate groups to isocyanurate groups of 100/0 to 75/25, 5) poly The isocyanate composition is at least one diisocyanate selected from an aliphatic diisocyanate and an alicyclic diisocyanate, and a high solid coating composition using the monohydric alcohol and polyhydric alcohol as raw materials, 6) the high solid coating A car body or a plastic part for a car coated with the composition, 7) The high solid coating composition relates to the car body or a plastic part for a car, which is a top clear paint.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The high-solids coating composition of the present invention comprises a curing agent composition containing (a) a base polyol composition and (b) a polyisocyanate composition. First, (a)
The base polyol composition will be described in detail. In the present invention, a base polyol composition containing an acrylic polyol having a number average molecular weight of 500 to 10,000 or a polyester polyol is used.

The acrylic polyol can be obtained, for example, by copolymerizing a polymerizable monomer having one or more active hydrogens in one molecule with another monomer copolymerizable therewith. For example, acrylic acid esters having active hydrogen such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate, or 2-hydroxyethyl methacrylate, 2-methacrylic acid-2- Methacrylic acid esters having active hydrogen such as hydroxypropyl, 2-hydroxybutyl methacrylate, 3-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate,

Alternatively, (meth) acrylic acid esters having polyvalent active hydrogen such as acrylic acid monoesters or methacrylic acid monoesters of triols such as glycerin and trimethylolpropane, polyglycols such as polyethylene glycol, polypropylene glycol and polybutylene glycol. A monoether of an ether polyol and a (meth) acrylic acid ester having the above active hydrogen,
An adduct of glycidyl (meth) acrylate with a monobasic acid such as acetic acid, propionic acid, p-tert-butylbenzoic acid, or ε-caprolactam in the active hydrogen of the (meth) acrylic acid ester having the above active hydrogen, γ
-Methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylic acid, if necessary, alone or as a mixture selected from the group of adducts obtained by ring-opening polymerization of lactones such as valerolactone. -N-butyl, acrylic acid esters such as 2-ethylhexyl acrylate,

Alternatively, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, methacrylic acid-n
-Butyl, isobutyl methacrylate, methacrylic acid-n
Methacrylic acid esters such as hexyl, cyclohexyl methacrylate, lauryl methacrylate, glycidyl methacrylate, acrylic acid, methacrylic acid, maleic acid,
Unsaturated carboxylic acids such as itaconic acid, acrylamide,
Unsaturated amides such as N-methylol acrylamide and diacetone acrylamide, or vinyl monomers having a hydrolyzable silyl group such as vinyltrimethoxysilane, vinylmethyldimethoxysilane and γ- (meth) acrylopropyltrimethoxysilane, A single selected from the group of other polymerizable monomers such as styrene, vinyltoluene, vinyl acetate, acrylonitrile, and dibutyl fumarate.
Alternatively, the mixture can be obtained by copolymerization by a conventional method. For example, it can be obtained by solution polymerization of the above-mentioned monomer component in the presence of a radical polymerization initiator such as a known peroxide or azo compound.

Polyester polyols include, for example, dibasic acids such as succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, and carboxylic acids such as 1,4-cyclohexanedicarboxylic acid alone. Or a mixture with ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, trimethylolpropane, glycerin, pentaerythritol, 2-methylolpropane Diol,
It can be obtained by performing a known condensation reaction with a polyhydric alcohol such as ethoxylated trimethylolpropane alone or in a mixture. This can be done, for example, by combining the above components and heating at about 160-220 ° C. Furthermore, for example, polycaprolactones obtained by ring-opening polymerization of lactones such as ε-caprolactone using a polyhydric alcohol can also be used as the polyester polyol.

In the base polyol composition used in the present invention, the above acrylic polyol or polyester polyol may be used alone or in combination.
Furthermore, the acrylic polyol or the polyester polyol may be mixed with another resin and used. Examples of other resins include polyether polyols, fluorine-containing polyols, aliphatic hydrocarbon polyols, silicon-containing polyols, polycarbonate polyols, epoxy resins, and alkyd polyols.
Further, the main component polyol composition of the present invention, the above acrylic polyol or polyester polyol is modified with an aliphatic diisocyanate, an alicyclic diisocyanate or a polyisocyanate obtained therefrom, a urethane modified acrylic polyol or a urethane modified polyester polyol, etc. Can be used.

The number average molecular weight of the base polyol composition used in the present invention is 500 to 10,000, preferably 500.
˜8,000, more preferably 500 to 5,000.
When the number average molecular weight is 500 or more, it becomes possible to design a high solid paint having a sufficient crosslink density.
When the number average molecular weight is 10,000 or less, the viscosity can be suppressed low. The number average molecular weight can be measured by gel filtration chromatography (hereinafter, GPC). GPC has, for example, a molecular weight of 1,000 to 1,000.
It can be adjusted by preparing a calibration curve using the molecular weight of polystyrene of about 00 as a standard.

The method of measuring GPC will be described below.
The measured values for the molecular weights of the base polyol composition and the polyisocyanate composition used in the present invention are all measured by the following measuring methods. Equipment used: HLC-812
0 (manufactured by Tosoh Corporation), column used: TSK GEL
Super H1000, TSK GEL Super
H2000, TSK GEL Super H3000
(All manufactured by Tosoh Corporation), sample concentration: 5 wt / vo
1%, carrier: THF, detection method: parallax refractometer, outflow rate 0.6 ml / min. , Column temperature 30 ° C.).

The calibration curve of GPC has a molecular weight of 50,000 to 2
050 polystyrene (GL Science Co., Ltd. PSS-06 (Mw 50000), BK13007 (M
p = 20000, Mw / Mn = 1.03), PSS-0
8 (Mw = 9000), PSS-09 (Mw = 400)
0), 5040-35125 (Mp = 2050, Mw /
Mn = 1.05) and hexamethylene diisocyanate-based polyisocyanate composition (duranate TPA-1)
00, manufactured by Asahi Kasei Corporation, isocyanurate trimer to heptamer (isocyanurate trimer molecular weight = 504,
Isocyanurate pentamer molecular weight = 840, isocyanurate heptamer molecular weight = 1176) and HDI (molecular weight = 1
68) as a standard. The base polyol used in the present invention is 5 to 300 mgKOH / g, preferably 10
-200 mgKOH / g, more preferably 20-150
It preferably has a hydroxyl group of mgKOH / g. When the hydroxyl value is 5 mgKOH / g or more, a tough coating film can be obtained. If 300 mgKOH / g or less,
It becomes possible to obtain a smooth coating film.

The curing agent composition containing the (b) polyisocyanate composition will be described below. In the present invention,
A curing agent composition containing a polyisocyanate composition is used. The polyisocyanate composition used in the present invention is a raw material of at least one diisocyanate selected from aliphatic diisocyanates and alicyclic diisocyanates, and the content of components having a molecular weight of 700 or less is 2 or less.
0 to 60% by mass, the ratio of the weight average molecular weight to the number average molecular weight is 1.2 to 5.0, and the ratio of the viscosity (unit mPa.s) of the polyisocyanate composition at 25 ° C. to the number average functional group number of the isocyanate group. Is expressed by the following equation. Viscosity (mPa.s) / number average number of functional groups ≦ 240

The polyisocyanate composition used in the present invention contains an aliphatic diisocyanate and an alicyclic diisocyanate as raw materials. Examples of such diisocyanates include, as aliphatic diisocyanates, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (hereinafter, HD
I), trimethylhexamethylene diisocyanate, lysine diisocyanate, and alicyclic diisocyanate include isophorone diisocyanate (hereinafter, IPDI),
Hydrogenated xylylene diisocyanate (hereinafter, hydrogenated XD
I), hydrogenated diphenylmethane diisocyanate (hereinafter,
Hydrogenated MDI), 1,4-diisocyanate cyclohexane and the like can be mentioned. HDI, IPDI, hydrogenated XDI, and hydrogenated MDI are preferable because they are relatively inexpensive and easily industrially available. Among them, HDI is most preferable because the viscosity of the obtained polyisocyanate composition tends to be low. Hereinafter, the aliphatic diisocyanate and the alicyclic diisocyanate are collectively referred to as diisocyanate.

The polyisocyanate composition used in the present invention has allophanate groups. A compound having an allophanate group is hereinafter referred to as an allophanate body,
It is mainly composed of monoallophanate and polyallophanate. Monoallophanate body is 2
It is a polyisocyanate produced from one diisocyanate molecule and one monohydric alcohol molecule, and has one allophanate group and two isocyanate groups in the molecule. Further, the polyallophanate body is a polyisocyanate produced from diisocyanate and polyhydric alcohol, and has two or more allophanate groups and four or more isocyanate groups in the molecule. The monoallophanate body is important as a component for lowering the viscosity of polyisocyanate, and the polyallophanate body is important as a component for improving curability. The polyisocyanate composition used in the present invention is a combination of a monoallophanate body and a polyallophanate body under specific conditions, and its characteristics are characterized by parameters such as molecular weight, average number of functional groups, and viscosity.

The polyisocyanate composition used in the present invention has a content of a component having a molecular weight of 700 or less in an amount of 20 with respect to the entire polyisocyanate composition in a state in which the organic solvent and the diisocyanate used as a raw material are substantially not contained. -60 mass%, preferably 23-55 mass%,
More preferably, it is 25 to 50 mass%. Molecular weight 70
The component of 0 or less is mainly composed of a monoallophanate body and has an effect of lowering the viscosity of the polyisocyanate composition. However, the number of functional groups in the monoallophanate body is 2, and the curability is low. When the content of the component having a molecular weight of 700 or less is 20% by mass or more, the viscosity is sufficiently low, and when the content is 60% by mass or less, sufficient curability is obtained.

The organic solvent referred to in the present invention is an organic solvent used for the purpose of diluting the polyisocyanate composition. Therefore, compounds having low solubility in the polyisocyanate composition and compounds that react with the polyisocyanate composition are not preferred. Specific examples of the organic solvent include, for example, aliphatic hydrocarbon solvents such as mineral spirit, aromatic hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, ethers such as dialkyl glycol. It is possible to use solvents of the system. In addition, commercially available petroleum hydrocarbon solvents such as HAWS, LAWS (manufactured by Shell Chemical Co., Ltd.), Solvesso 100 and 150 (manufactured by Exxon Chemical Chemical Co., Ltd.), which are a mixture of aromatic and aliphatic hydrocarbons, may be used.

As a component having a molecular weight of 700 or less, in addition to the monoallophanate form, depending on the reaction conditions, an isocyanurate trimer in which three molecules of diisocyanate are subjected to isocyanurate reaction, a uretdione form in which two molecules of diisocyanate are reacted to form uretdione, and a monoalcohol In some cases, a monourethane body in which one molecule of diisocyanate has undergone a urethane reaction, a diurethane body in which two molecules of a diisocyanate have undergone a urethane reaction, or a compound in which only one molecule of diisocyanate has undergone an allophanatization reaction is contained in the diurethane body. The number of functional groups of these compounds is at most 3, the curability is not so high, and the effect of lowering the viscosity of the polyisocyanate composition is not high. These compounds may be included as long as the balance between the curability and the viscosity of the polyisocyanate composition is not disturbed, that is, within the range of the specific numerical values of the polyisocyanate composition used in the present invention.

In the present invention, the content of the component having a molecular weight of 700 or less is defined as the ratio of the areas of the peaks having a molecular weight of 700 or less obtained by a GPC differential refractometer. The term "substantially free from" as used in the present invention means the viscosity of the polyisocyanate composition and the isocyanate group content (hereinafter referred to as NC
O%) does not change significantly due to the inclusion of the solvent and the raw material diisocyanate. As a rule of thumb, the content of the solvent and diisocyanate is less than 1% by mass based on the polyisocyanate composition. In the present invention, all of the characteristic requirement values described below are values in a state in which the solvent and the raw material diisocyanate composition are not substantially contained.

The polyisocyanate composition used in the present invention has a weight average molecular weight (Mw) and a number average molecular weight (Mn).
Ratio (Mw / Mn) is 1.2 to 5.0, preferably 1.2 to 4.0, and more preferably 1.2 to 4.0.
It is 3.0. Mw / Mn indicates in what proportion the monoallophanate body and the polyallophanate body exist, and is one of the indexes showing the balance between viscosity and curability. If Mw / Mn is 1.2 or more, sufficient curability can be achieved. When it is 5.0 or less, low viscosity can be achieved. Note that Mn and M
w can be measured by GPC.

The Mn of the polyisocyanate composition used in the present invention is 450 to 1200, preferably 500 to 1.
000, more preferably 550 to 900, and Mw is 540 to 6000, preferably 600 to 5000, and more preferably 660 to 4500. Sufficient curability can be achieved when Mn is 500 or more and Mw is 540 or more. When Mn is 1200 or less and Mw is 6000 or less, low viscosity can be achieved. The isocyanate group content of the polyisocyanate composition used in the present invention is 8 to 2 relative to the polyisocyanate composition.
It is 5% by mass, preferably 10 to 23% by mass, more preferably 12 to 22% by mass. In the case of 8% by mass to 25% by mass, sufficient curability and low viscosity can be achieved. N
The CO% can be determined, for example, by reacting the isocyanate group of the polyisocyanate composition with an excess of an amine (such as dibutylamine) and back titrating the remaining amine with an acid such as hydrochloric acid.

The number average functional group number of isocyanate groups of the polyisocyanate composition used in the present invention (hereinafter referred to as fn)
Is 2.6 to 5.0, preferably 2.8 to 4.5, and more preferably 3.0 to 4.0. If it is 2.6 or more, sufficient curability can be achieved. When it is 5.0 or less, low viscosity can be achieved. The weight average functional group number is originally suitable as an index of curability.
In the case of a polyisocyanate composition, since there is no clear proportional relationship between the molecular weight and the number of functional groups, it is difficult to obtain the number of weight average functional groups from the weight average molecular weight. Therefore, in the present invention, the number average number of functional groups is used as one of the indices showing curability. fn can be calculated by the following equation. fn = Mn × NCO% / 4200

The viscosity of the polyisocyanate composition used in the present invention at 25 ° C. is 100 to 1000 mPa.s.
s, preferably 150 to 900 mPa.s. s, more preferably 200 to 800 mPa.s. s. When it is 100 or more, sufficient curability can be achieved. 1000m
Pa. With a viscosity of s or less, high solidification of an automobile coating composition can be achieved. The polyisocyanate composition used in the present invention has a viscosity at 25 ° C. and a f
The ratio of n satisfies the following condition. Viscosity (mPa.s) / fn ≦ 240 This ratio is suitably 240 or less, preferably 220 or less, and more preferably 200 or less. When this ratio is 240 or less, a polyisocyanate composition having low viscosity and high curability can be obtained. In the present invention, the polyisocyanate composition having an allophanate group has a content of the above-mentioned component having a molecular weight of 700 or less, Mw.
When the conditions of / Mn and viscosity / fn are satisfied, low viscosity and excellent curability can be exhibited.

The polyisocyanate composition used in the present invention may contain a component other than the allophanate form, if necessary, as long as it falls within the range of these conditions. Examples of such a component include an isocyanurate body, a biuret body, a uretdione body, and a urethane adduct body. Among these, the isocyanurate body inevitably contains a polymer component, and therefore it is not preferable that the content is large. The polyisocyanate composition of the present invention contains the isocyanurate group in such a range that the molar ratio of allophanate groups to isocyanurate groups is 100/0 to 75/25, preferably 100/0.
80/20, more preferably 100/0 to 85/15,
Most preferably, 100/0 to 90/10 is suitable.
The molar ratio of allophanate groups to isocyanurate groups is 1
Low viscosities can be achieved in the case of 00/0 to 75/25.

The molar ratio of the allophanate group to the isocyanurate group can be determined by NMR. A method for measuring a polyisocyanate composition using hexamethylene diisocyanate and an isocyanate prepolymer obtained therefrom as a raw material by ¹ H-NMR is shown below. In the present invention, the molar ratio of allophanate group: isocyanurate group is measured under the following conditions. ¹ H-NMR measurement method: A polyisocyanate composition is dissolved in deuterium chloroform at a concentration of 10% by mass (0.03% by mass of tetramethylsilane is added to the polyisocyanate composition). As a chemical shift standard, the hydrogen signal of tetramethylsilane was set to 0 ppm. ¹ H-N
The signal of a hydrogen atom bonded to the nitrogen of the allophanate group around 8.5 ppm (1 mol of hydrogen atom to 1 mol of the allophanate group) and 3.8 measured by MR.
A hydrogen atom of a methylene group adjacent to an isocyanurate group of about 5 ppm (6 moles per 1 mole of isocyanurate group)
The area ratio of the signal (mol hydrogen atom) is measured.

Allophanate group: isocyanurate group =
(Signal area near 8.5 ppm): (3.85 pp
In addition, the uretdione compound, which is bifunctional, not only lowers the cross-linking ability but also dissociates due to heat or the like to generate HDI.
Is easy to generate. It is suitable for safety that the uretdione compound is contained in an amount of 10% by mass or less, preferably 7.5% by mass or less, and more preferably 5% by mass or less. Measurements of uretdione amount using FT-IR, and the height of the peak of the uretdione group of about 1770 cm ^-1, a ratio of the height of the peak of the isocyanurate group of about 1690 cm ^-1, quantitated using an internal standard Good.

Next, a method for producing the polyisocyanate composition used in the present invention will be described. The polyisocyanate composition used in the present invention is obtained by allophanating a compound obtained by reacting at least one diisocyanate selected from an aliphatic diisocyanate and an alicyclic diisocyanate with a monohydric alcohol and a polyhydric alcohol. You can As monohydric alcohol,
Those having 20 or less carbon atoms, preferably 15 or less carbon atoms, and more preferably 13 or less carbon atoms are suitable. Examples of such monohydric alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, i-butanol, 1-pentanol, 2-pentanol, isoamyl alcohol,
Saturated aliphatic alcohols such as 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, 3,3,5-trimethyl-1-hexanol, tridecanol and pentadecanol, cyclopenes Saturated cycloaliphatic alcohols such as tanol, cyclohexanol, methylcyclohexanol and trimethylcyclohexanol, unsaturated fatty alcohols such as propenol, butenol, hexenol and 2-hydroxyethyl acrylate, ethylene glycol monoalkyl ether, propylene glycol monoalkyl Examples thereof include alcohols having an ether bond such as ether and alcohols having an ester bond. Only one of these may be used, or two or more may be used. A compound having a so-called phenolic hydroxyl group can also be used as the monohydric alcohol. Among these, saturated aliphatic alcohols and saturated cyclic aliphatic alcohols have good weather resistance and are more preferable.

The polyhydric alcohol is a compound having two or more hydroxyl groups. The number of hydroxyl groups is suitably 2 to 8, preferably 2 to 6, and more preferably 2 to 4. When the number of hydroxyl groups is 2 or more, the polyisocyanate composition can have sufficient curability. When the number of hydroxyl groups is 8 or less, a low viscosity polyisocyanate composition can be produced. The molecular weight of the polyhydric alcohol is 62 to 50.
00, preferably 62 to 3000, more preferably 62.
~ 2000 is suitable. There are no polyhydric alcohols with a molecular weight below 62. If the molecular weight is 5000 or less,
The viscosity of the polyisocyanate composition can be lowered. A compound having a phenolic hydroxyl group may be used as the polyhydric alcohol.

Examples of polyhydric alcohols are as follows. Examples of the compound having two hydroxyl groups include ethylene glycol, 1,2-propanediol,
1,3-propanediol, 1,4-butanediol,
1,3-butanediol, 1,2-butanediol,
1,5-pentanediol, 1,6-hexanediol, methylpentanediol, cyclohexanedimethanol, methylpentanediol, neopentyl glycol, aliphatic diols such as hydrogenated bisphenol A, diethylene glycol, triethylene glycol, polyethylene glycol, Polyether polyols such as polypropylene glycol, polyester polyols,
Examples thereof include compounds having a phenolic hydroxyl group such as bisphenol A. Of these, aliphatic diols are preferable because they have excellent weather resistance. Since polyester polyols and polyether polyols have the characteristic that the coating film obtained can be softened,
preferable.

Examples of the compound having three hydroxyl groups include glycerin and 2-methyl-2-hydroxymethyl-
1,3-propanediol, 2,4-hydroxy-3-
Examples thereof include aliphatic triols such as hydroxymethylpentane and 1,2,6-hexanetriol, polyester polyols and polyether polyols. Examples of the compound having 4 or more hydroxyl groups include tetritol such as erythrose, pentitol such as xylitol, and sugar alcohol such as hexitol such as sorbitol. 1 as polyhydric alcohol
Only one species may be used, or two or more species may be used in combination.

As a method for producing the polyisocyanate composition used in the present invention, a monoallophanate body and a polyallophanate body are independently prepared by separately subjecting a monohydric alcohol and a polyhydric alcohol to a urethanization reaction and an allophanatization reaction. After that, a method of mixing them can be adopted. In this case, the molar ratio of the diisocyanate to the isocyanate group of the monohydric alcohol and the hydroxyl group is 4 /
1 to 100/1, preferably 5/1 to 50/1, more preferably 6/1 to 30/1 are suitable. If the isocyanate content is 4/1 or more, the viscosity can be kept low. When the hydroxyl group is present at 100/1 or more, sufficient production efficiency can be maintained. The molar ratio of the diisocyanate to the isocyanate group of the polyhydric alcohol and the hydroxyl group is 6
/ 1 to 100/1, preferably 8/1 to 40/1, more preferably 10/1 to 20/1. When the isocyanate group is excessively 6/1 or more, a low-viscosity polyisocyanate can be produced. If the hydroxyl group is present at 100/1 or more, the production efficiency can be maintained.

The obtained monoallophanate form and polyallophanate form are mixed in a mass ratio of 10/90 to 65/35, preferably 10/90 to 60/40, 15/85 to 55/45. The polyisocyanate composition used in the invention can be obtained. By adding monoallophanate in an amount of 10/90 or more, a low-viscosity polyisocyanate composition can be obtained. 65
A polyisocyanate composition having high curability can be obtained by incorporating polyallophanate in an amount of / 35 or more. Of course, as described above, if necessary, an isocyanurate body or the like may be contained.
The isocyanurate-forming reaction or the like may be carried out before, simultaneously with, or after the urethanization reaction or the allophanate-forming reaction.
You may mix an isocyanurate body etc. with the mixture of a polyallophanate body.

The polyisocyanate composition used in the present invention can also be obtained by a method of carrying out a urethanization reaction and an allophanate reaction together with a monohydric alcohol and a polyhydric alcohol. In this case, the molar ratio of the hydroxyl groups of the monohydric alcohol and the polyhydric alcohol is 10/90 to 65.
/ 35, preferably 10/90 to 60/40, more preferably 15/75 to 85/45. By adding a monohydric alcohol to 10/90 or more, a low viscosity can be achieved. 65/3
By adding a polyhydric alcohol to 5 or more, a polyisocyanate composition having high curability can be obtained. The molar ratio of the isocyanate group of the diisocyanate to the total of the hydroxyl groups of the monohydric alcohol and the polyhydric alcohol is 5/1 to 100/1, preferably 8/1 to 60 /.
1, more preferably 10/1 to 30/1 is suitable.
When the isocyanate is present in excess of 5/1 or more, a low-viscosity polyisocyanate can be produced. The production efficiency can be maintained due to the presence of the hydroxyl group in 100/1 or more.

Considering the ease of production, it is more preferable to use a monohydric alcohol and a polyhydric alcohol together with, if necessary, a urethanization reaction and then an allophanate reaction. The urethanization reaction is 0 to 200 ° C, preferably 20 to 150 ° C, more preferably 40 to 120 ° C.
It is carried out at 0 ° C. for 10 minutes to 24 hours, preferably 15 minutes to 15 hours, more preferably 20 minutes to 10 hours. If it is 0 ° C. or higher, an appropriate reaction rate can be achieved. When the temperature is 200 ° C. or lower, suppression of side reactions can be achieved at the same time.
When the reaction time is 10 minutes or more, the reaction can be completed. Within 24 hours, side reactions can be suppressed. The urethanization reaction can be performed without a catalyst or in the presence of a tin-based catalyst, an amine-based catalyst, or the like.

The allophanatization reaction must be carried out under the following specific conditions. Generally, when an allophanate-forming reaction is carried out, an isocyanurate-forming reaction is often accompanied as a side reaction. However, the isocyanurate-forming reaction tends to form a multimer, and the resulting polyisocyanate composition tends to have a high viscosity. Therefore, in the present invention, the allophanatization is carried out under the condition that the isocyanurate-forming reaction is suppressed as much as possible. The conditions for the allophanatization reaction for producing the polyisocyanate composition used in the present invention are as follows: the product obtained by the allophanatization reaction has a molar ratio of allophanate groups to isocyanurate groups of 1
00/0 to 75/25, preferably 100/0 to 85 /
15, more preferably 100/0 to 90/10. When the ratio of allophanate is 75/25 or more, it becomes possible to increase the number of functional groups while keeping the viscosity of the polyisocyanate composition low.

In order to carry out the allophanatization reaction under such conditions, it is preferable to use an allophanatization catalyst. Examples of preferred catalysts include lead-containing compounds, zinc-containing compounds, tin-containing compounds, zirconium-containing compounds,
A compound containing bismuth, a compound containing calcium, a compound containing magnesium, and a compound containing lithium.
One or more of these compounds can be used. Among these catalysts, more preferred are compounds containing zinc, compounds containing lead, compounds containing tin, compounds containing zirconium, compounds containing bismuth, and more preferable compounds containing zirconium and bismuth. Compounds containing, most preferably compounds containing zirconium.

The compound containing zinc is a compound containing zinc in the molecule, and zinc organic carboxylates such as zinc 2-ethylhexanoate and zinc naphthenate are preferable. The compound containing lead is a compound containing lead in its molecule, and organic lead carboxylates such as lead 2-ethylhexanoate, lead octanoate, and lead naphthenate are preferable. The compound containing tin is a compound containing tin in the molecule, and examples thereof include tin (II) salts and organic tin salts of organic acids. Examples of preferable tin compounds are tin (II) chloride, bromide, iodide, tin (II) carboxylate and dialkyltin dicarboxylate. Of these, tin (II) carboxylate is preferable.

The compound containing zirconium is a compound containing zirconium in the molecule. As the zirconium compound, for example, tetraalkoxyzirconium, zirconium carboxylate, etc., zirconyl carboxylate,
Examples include zirconyl compounds such as zirconyl alcoholate, dialkyl zirconyl, and zirconyl carbonate. In particular, zirconyl carboxylate and tetraalkoxy zirconium are preferable in view of reactivity and allophanate formation ratio, and among them, zirconyl carboxylate is most preferable because the allophanate formation ratio is very high. The molecular formula of the zirconyl compound is shown below.

[0044]

[Chemical 1] In the formula, R ₁ and R ₂ represent an alkylcarboxyoxy group, an alkoxy group, an alkyl group, a halogen group, and an inorganic acid mark.
That is, when R ₁ and R ₂ in the above chemical formula are alkylcarboniumoxy groups, the zirconyl compound is a zirconyl carboxylate. Examples of the organic carboxylic acid include aliphatic carboxylic acid, alicyclic carboxylic acid, unsaturated carboxylic acid, hydroxyl group-containing carboxylic acid, halogenated alkyl carboxylic acid and the like, and polybasic carboxylic acid such as dicarboxylic acid and tricarboxylic acid. . The compound containing bismuth is a compound containing bismuth in the molecule. Examples of the compound containing bismuth include bismuth carboxylate and bismuth carbonate. Bismuth carboxylate is particularly preferable.

Lead carboxylate, tin (II) carboxylate,
Dialkyl tin dicarboxylate, zirconium carboxylate, zirconyl carboxylate, bismuth carboxylate,
Examples of the carboxylic acid as a raw material of tin carboxylate and lead carboxylate include formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, caproic acid, octanoic acid, 2-ethylhexanoic acid, decanoic acid. , Saturated aliphatic carboxylic acids such as dodecanoic acid, tetradecanoic acid and pentadecanoic acid, saturated cyclic carboxylic acids such as cyclohexanecarboxylic acid and cyclopentanecarboxylic acid, mixtures of the above carboxylic acids such as naphthenic acid, oleic acid, linoleic acid and linolenic acid And unsaturated carboxylic acids such as benzoic acid, toluic acid, and diphenylacetic acid. Among these compounds, zirconyl naphthenate, zirconyl 2-ethylhexanoate, bismuth naphthenate, bismuth 2-ethylhexanoate, tin 2-ethylhexanoate, tin naphthenate, lead 2-ethylhexanoate, lead naphthenate Is preferable because it is relatively inexpensive, industrially available, and has a high selectivity for the allophanatization reaction. Zirconyl naphthenate and 2-ethylhexane zirconyl are particularly preferred because of their high safety.

The amount of the allophanatization catalyst used is 0.001 to 2.0% by mass, preferably 0.01 to 0.5% by mass, based on the total mass of the reactants.
When it is 0.001% by mass to 2% by mass, the allophanate-forming reaction can be carried out at an appropriate reaction rate. In the present invention, the method of adding the allophanatization catalyst is not limited. For example, it may be added before the production of the compound containing a urethane group, that is, before the reaction of the diisocyanate and the alcohol, during the reaction of the diisocyanate and the alcohol, or after the production of the compound containing a urethane group. You may. Further, as a method of addition, a required amount of allophanatization catalyst may be added all at once,
It may be added in several divided portions. Also, a method of continuously adding at a constant addition rate can be adopted.

The allophanatization reaction is generally carried out in the range of 20 to 2
It is carried out at a temperature of 00 ° C. Preferably 30-180 ° C
And more preferably 60 to 160 ° C. 20 ° C
If it is above, an allophanate-ized reaction can be advanced at an appropriate reaction rate, without causing a side reaction. 20
If it is 0 ° C. or lower, it is possible to prevent side reactions and coloring. In the allophanate-forming reaction in producing the polyisocyanate composition used in the present invention, it is preferable that the conversion rate from urethane groups to allophanate groups is as high as possible. By converting the urethane group into the allophanate group, it becomes possible to increase the number of functional groups in the isocyanate group while maintaining the low viscosity.

The urethanization reaction and allophanate reaction proceed in the absence of solvent, but if necessary, butyl acetate,
An organic solvent having no reactivity with an isocyanate group such as methyl ethyl ketone, toluene, xylene, a hydrocarbon-based solvent, or an aromatic solvent can be used as a solvent. The process of the reaction in the present invention is performed by using the NCO of the reaction mixture.
It can be tracked by measuring% or by measuring the refractive index. The allophanate reaction can be stopped by cooling to room temperature or by adding a reaction terminator, but when an allophanate-forming catalyst is used, it is preferably stopped by adding a reaction terminator. By stopping the reaction, a long-term stable polyisocyanate composition can be obtained. The amount of the reaction terminator added is 0.2 to 100 times, preferably 0.5 to 50 times, and more preferably 1.0 to 100 times the molar amount of the allophanatization catalyst.
~ 20 times the molar amount. If the molar amount is 0.2 times or more, the catalyst can be completely deactivated. 100
When the amount is less than the double molar amount, it becomes possible to obtain a polyisocyanate composition free from turbidity. As a reaction terminator,
Any material may be used as long as it deactivates the allophanatization catalyst.

Examples of the reaction terminator are phosphoric acid, pyrophosphoric acid, metaphosphoric acid, compounds showing phosphoric acidity such as polyphosphoric acid, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, monoalkyl or dialkyl esters of polyphosphoric acid, and monochloro acid. Halogenated acetic acid such as acetic acid, benzoyl chloride, sulfonic acid ester, sulfuric acid, sulfuric acid ester, ion exchange resin,
Examples include chelating agents. From an industrial point of view, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, phosphoric acid monoalkyl ester and phosphoric acid dialkyl ester are preferable because they are unlikely to corrode stainless steel. Examples of phosphoric acid monoesters and phosphoric acid diesters include phosphoric acid monoethyl ester, phosphoric acid diethyl ester, phosphoric acid monobutyl ester and phosphoric acid dibutyl ester, phosphoric acid mono (2-ethylhexyl) ester, and phosphoric acid diester. (2-ethylhexyl) ester and the like can be mentioned.

Furthermore, phosphoric acid, pyrophosphoric acid, metaphosphoric acid and polyphosphoric acid which do not substantially contain water are more preferable as the terminating agent. When used in a state of not containing water, the reaction product of the terminating agent and the catalyst is likely to precipitate, and thus the reaction product of the terminating agent and the catalyst is less likely to remain in the polyisocyanate composition. . Furthermore, when used in a state of not containing water, the reaction product of water and isocyanate does not mix into the polyisocyanate, so that the viscosity of the polyisocyanate does not increase and the dilutability with respect to the organic solvent does not decrease. There is also. The term “substantially free of water” as used in the present invention means that water may be included as long as the above effects are exhibited. Less than 0.0% by weight, preferably less than 2.0% by weight, more preferably less than 0.0%.
It is less than 50% by mass.

After completion of the reaction, the polyisocyanate composition needs to be separated from unreacted diisocyanate and solvent. Examples of the method for separating unreacted diisocyanate and solvent include thin film distillation method and solvent extraction method. The reaction in the present invention can carry out a urethane-forming reaction and an allophanate-forming reaction in one reactor. Alternatively, the two reactors may be connected to carry out the urethanization reaction step and the allophanate reaction step separately. Alternatively, it can be continuously carried out by arranging several reactors vertically.

The high solid coating composition of the present invention using the curing agent composition containing the base polyol composition and the polyisocyanate composition will be described in detail below.
The nonvolatile content of the high solid coating composition of the present invention during coating is preferably 65% by mass or more, more preferably 70% by mass or more. If the nonvolatile content at the time of coating is 65% or more, the amount of organic solvent released into the atmosphere can be reduced. The nonvolatile content is measured, for example, by coating a coating composition at 110 ° C
It can be measured by drying for 1 hour and comparing the heating residue with the mass before heating. The equivalent ratio of the isocyanate group to the hydroxyl group (NCO / OH) of the base polyol composition and the polyisocyanate composition used in the present invention
Ratio) is 0.2 to 5.0, preferably 0.4 to 3.0,
More preferably, 0.5 to 2.0 is suitable. When it is 0.2 or more, a tough coating film can be obtained. 5.
If it is 0 or less, a smooth coating film can be obtained.

The main component polyol composition and the curing agent composition containing the polyisocyanate composition used in the present invention can be used as a mixture with an organic solvent. In this case, the organic solvent preferably does not have a functional group that reacts with a hydroxyl group and an isocyanate group. Further, the organic solvent is preferably compatible with the curing agent composition containing the polyisocyanate composition used in the present invention and the base polyol composition. As such organic solvents, ester compounds, ether compounds, ketone compounds, aromatic compounds, ethylene glycol dialkyl ether compounds, polyethylene glycol dicarboxylate compounds, hydrocarbon solvents generally used as coating solvents Alternatively, an aromatic solvent or the like may be used.

In the high solid coating composition of the present invention,
Depending on the purpose and application, it is used in the technical field such as a catalyst, a pigment, a leveling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, and a surfactant within a range that does not impair the effects of the present invention. It is also possible to mix and use various additives described above. These may be contained in any of the main component polyol composition and the curing agent composition containing the polyisocyanate composition. Examples of the catalyst for accelerating curing are dibutyltin dilaurate, tin 2-ethylhexanoate, 2-
Zinc ethylhexanoate, metal salts such as cobalt salt, triethylamine, pyridine, methylpyridine, benzyldimethylamine, N, N-dimethylcyclohexylamine, N-methylpiperidine, pentamethyldiethylenetriamine, N, N′-endoethylenepiperazine, And tertiary amines such as N, N′-dimethylpiperazine.

The high-solids coating composition of the present invention uses a base polyol containing a low molecular weight acrylic polyol or polyester polyol and a low-viscosity, high-functionality polyisocyanate composition. The solid content of the composition can be increased and the amount of organic solvent used can be reduced. The obtained coating film is
In addition to a good appearance and excellent weather resistance, it is also characterized by excellent scratch resistance. Therefore, the high-solid coating composition of the present invention is a high-solid coating composition that can be used for automobiles, constructions, home appliances, and information devices such as personal computers and mobile phones. In particular, it is suitable for coating exterior parts of automobiles, which are required to have excellent appearance, weather resistance and scratch resistance. Among them, it is suitable as a paint for new car top coating on the body, plastic parts such as door mirrors and wheels, or paint for automobile repair. Furthermore, among them, it is suitable for top clear applications where weather resistance and surface smoothness are required at a very high level.

Examples of the method for synthesizing the polyisocyanate composition used in the present invention and the high solid coating composition of the present invention will be described below. For the number average molecular weight and the weight average molecular weight, GPC (apparatus used: HLC-8120
(Tosoh Corporation), column used: TSK GEL
SuperH1000, TSK GEL SuperH
2000, TSK GEL Super H3000 (all manufactured by Tosoh Corporation), sample concentration: 5 wt / vol
%, Carrier: THF, detection method: parallax refractometer, outflow rate 0.6 ml / min. , Column temperature 30 ° C.). The calibration curve of GPC has a molecular weight of 50,000 to 205.
0 polystyrene (PS manufactured by GL Sciences Inc.
S-06 (Mw 50000), BK13007 (Mp =
20000, Mw / Mn = 1.03), PSS-08
(Mw = 9000), PSS-09 (Mw = 400)
0), 5040-35125 (Mp = 2050, Mw /
Mn = 1.05) and an HDI-based polyisocyanate composition (Duranate TPA-100, manufactured by Asahi Kasei Corporation)
To isomer of the isocyanurate (7) (isocyanurate trimer molecular weight = 504, isocyanurate pentamer molecular weight = 840, isocyanurate heptamer molecular weight = 117
6) and HDI (molecular weight = 168) were prepared as standards.

The ratio of allophanate groups to isocyanurate groups was determined by ¹ H-NMR (FT-NMR manufactured by Bruker).
DPX-400) and a hydrogen signal on the nitrogen atom of the allophanate group near 8.5 ppm and 3.8 p
It was determined from the area ratio of the hydrogen signal of the methylene group adjacent to the nitrogen atom of the isocyanurate ring of the isocyanurate group near pm. The NCO content was determined by back titration with 1N hydrochloric acid after neutralizing the isocyanate groups with an excess of 2N amine. The viscosity was measured at 25 ° C. using an E-type viscometer (Tokimec Co., Ltd.). A standard rotor (1 ° 34 ′ × R24) is used for the measurement, and the rotation speed is as follows. 100r. p. m. (When less than 128 mPa.s) 50r. p. m. (128 mPa.s-256 mP
a. s) 20r. p. m. (256 mPa.s-640 mP
a. s) 10r. p. m. (640 mPa.s to 1280 m
Pa. s) 5r. p. m. (1280 mPa.s to 2560 mP
a. s)

The gel fraction was determined by immersing about 0.1 g of the coating film in acetone at 20 ° C. for 24 hours, taking out the coating film, and then at 80 ° C. 1
It was determined from the mass of the coating film dried for a period of time. The scratch resistance test was performed by the following method using a rubbing tester. The 20 ° gloss of the coated surface was measured beforehand. A cleanser (trade name Marzen Cleanser, manufactured by Marzen Cleanser Co., Ltd.) and water were mixed in a ratio of 3: 2 to prepare an abrasive. About 1 g of the abrasive was attached to a sponge of a rubbing tester (manufactured by Taihei Rika Kogyo Co., Ltd.), a load of 200 g was applied, and the coating film of the test plate was rubbed 20 times back and forth. Then, the coated surface was washed with running water and naturally dried, and then the 20 ° gloss of the coated surface was measured. 2 according to the following formula
The 0 ° gloss retention rate is calculated, and the value is used as the evaluation value of scratch resistance. 20 ° gloss retention = (20 ° gloss after test / 2 before test)
0 ° gloss) x 100

[0059]

[Synthesis Example 1] (Synthesis Example of Base Polyol Composition) Solvesso # 150 (solvent manufactured by Exxon Chemical Co., Ltd.) 1 was placed in a four-necked flask equipped with a stirrer, a thermometer, and a cooling tube.
After charging 20.0 g and xylene 60.0 g, replacing the inside with nitrogen, and heating to 120 ° C., the following (meta) is described.
Acrylic monomer and benzoyl peroxide 8.0
g was added dropwise over 2 hours and reacted with stirring. After the dropping was completed, the reaction was further continued at 120 ° C. for 4 hours to obtain a base polyol composition. (Meth) acrylic monomer used as a raw material Methyl methacrylate 128.8 g n-Butyl acrylate 84.8 g Cyclohexane methacrylate 80.0 g 2-Hydroxyethyl methacrylate 74.4 g Styrene 32.0 g The obtained main component polyol composition has a nonvolatile content. 70%, hydroxyl value = 80.0 mg KOH / g (based on resin content),
It had a Tg of 40.1 ° C. and a number average molecular weight of 1,700.

[0060]

[Synthesis example 2] (Synthesis example of curing agent composition) The inside of a four-necked flask equipped with a stirrer, a thermometer, and a cooling tube was replaced with nitrogen, and HDI: 1211 g and isobutanol 15.8.
Then, 22.9 g of 1,4-butanediol was charged and a urethanization reaction was carried out at 90 ° C. for 1 hour with stirring. 130 ° C
Then, 0.43 g of a 20% solid content mineral spirit solution of zirconyl 2-ethylhexanoate as a catalyst for allophanatization (manufactured by Nippon Kagaku Sangyo Co., Ltd., product name "Nikka Octix Zirconium 12%" diluted with mineral spirits) added. After 40 minutes, when the refractive index of the reaction solution reached 0.0055, the solid content of pyrophosphoric acid was 3
The reaction was stopped by adding 0.80 g of a 9% ethanol solution (8 moles to the allophanatization catalyst). Using the falling film distillation apparatus, the first time 160 ° C (0.2 Tor),
Unreacted HDI was removed at 150 ° C. (0.1 Tor) for the second time. The obtained polyisocyanate composition was a transparent liquid and had a yield of 280 g and a viscosity of 550 mPa.s. s, NC
The O content was 20.3%. When NMR was measured, the allophanate / isocyanurate molar ratio was 97/3. Data such as molecular weight are shown in Table 1.

[0061]

[Synthesis example 3] (Synthesis example of curing agent composition) HDI: 1409 g and isobutanol 9.2 in the same apparatus as in Synthesis example 2.
g and 1,2.2-butanediol (32.2 g) were charged, and a urethanization reaction was carried out at 90 ° C. for 1 hour with stirring. 130 ° C
Then, 0.50 g of a 20% solid content mineral spirit solution of zirconyl 2-ethylhexanoate was added as an allophanate formation catalyst. After 30 minutes, when the refractive index of the reaction solution reached 0.0055, the solid content of pyrophosphoric acid was 39%.
The reaction was stopped by adding 0.92 g of an ethanol solution (8 times mol to the allophanatization catalyst). Unreacted HDI was removed under the same conditions as in Synthesis Example 2. The resulting polyisocyanate composition is a clear liquid and has a yield of 334
g, viscosity 710 mPa.s. The s and NCO content was 20.6%. When NMR was measured, the allophanate / isocyanurate molar ratio was 97/3. Data such as molecular weight are shown in Table 1.

[0062]

[Synthesis Example 4] (Synthesis example of curing agent composition) HDI: 862.0 g and isobutanol 3 were placed in the same apparatus as in Synthesis Example 2.
8.0 g was charged and the urethanization reaction was carried out at 90 ° C. for 1 hour under stirring. At 130 ° C., 0.30 g of a 20% solid content mineral spirit solution of zirconyl 2-ethylhexanoate was added as an allophanatization catalyst. After 30 minutes, when the refractive index of the reaction solution increased to 0.0055, 0.56 g of a solution of pyrophosphoric acid in a solid content of 39% in ethanol (8 moles relative to the allophanatization catalyst) was added to stop the reaction. Under the same conditions as in Synthesis 1 of Polyisocyanate Composition, unreacted HDI was removed. The obtained polyisocyanate composition is designated as a-1.

Then, in the same manner as in Synthesis 1 of polyisocyanate composition, HDI: 872.3 g and 1,9-nonanediol 27.7 g were charged in an apparatus and stirred at 130 ° C. for 1 hour.
The urethane reaction was carried out for an hour. At 130 ° C., 0.31 g of a zirconyl 2-ethylhexanoate solid content 20% mineral spirit solution was added as an allophanatization catalyst. After 30 minutes, when the increase in the refractive index of the reaction solution reached 0.0035, 0.57 g of a solid solution of pyrophosphoric acid in a 39% ethanol solution (8 times the molar amount of the allophanatization catalyst)
Was added to stop the reaction. Unreacted HDI was removed under the same conditions as in Synthesis Example 2. The polyisocyanate composition obtained was designated as a-2. a-1 and a-2 and mass ratio 30/7
When mixed at a viscosity of 450 mPa.s. s, NCO%
A 19.5% polyisocyanate composition was obtained. NMR
Was measured, the molar ratio of allophanate / isocyanurate was 97/3.

[0064]

[Synthesis example 5] (Synthesis example of curing agent composition) In the same manner as in synthesis example 2, HDI: 881.8 g and neopentyl glycol 18.2 g were charged in an apparatus, and urethanization reaction was carried out at 130 ° C for 1 hour under stirring. It was Solid content of zirconyl 2-ethylhexanoate 20 at 130 ° C. as an allophanatization catalyst
0.31 g of a% mineral spirits solution was added. After 25 minutes, when the refractive index of the reaction solution reached 0.0035, 0.57 g of a 39% solid solution of pyrophosphoric acid in ethanol
The reaction was stopped by adding (8 times mol to the allophanatization catalyst). Unreacted HDI under the same conditions as in Synthesis Example 2
Was removed. The obtained polyisocyanate is designated as a-3. Polyisocyanates a-1 and a-3 obtained in Synthesis Example 5
When mixed with a mass ratio of 30/70, the viscosity is 580 mP
a. A polyisocyanate composition having an s and NCO% of 20.4% was obtained. When NMR was measured, allophanate /
The isocyanurate molar ratio was 97/3.

[0065]

[Synthesis example 6] (Synthesis example of curing agent composition used in comparative example)
HDI (1000 g) and 2-ethylhexanol (30 g) were charged in the same apparatus as in Synthesis Example 2, and a urethanization reaction was carried out at 80 ° C. for 1 hour under stirring. At 80 ° C., 0.05 g of tetramethylammonium caprate as an isocyanurate-forming catalyst was added. 2 hours later, when the refractive index of the reaction solution increased to 0.011, 85% phosphorus aqueous solution 0.10 g
(4 times mol relative to the catalyst) was added to stop the reaction. When the NMR of the reaction solution was measured, the production ratio of allophanate groups and isocyanurate groups was 40:60. Then, HDI was removed in the same manner as in Synthesis Example 2. The resulting polyisocyanate composition is a transparent liquid,
Yield 288 g, viscosity 450 mPa.s. s, NCO content 2
It was 0.6%. Data such as molecular weight are shown in Table 1.

[0066]

[Synthesis Example 7] (Synthesis example of curing agent composition used in Comparative Example)
HDI: 600 g was charged in the same apparatus as in Synthesis Example 2, and a urethanization reaction was carried out at 60 ° C. for 1 hour under stirring. 60 ° C
Then, 0.07 g of tetramethylammonium caprate as an isocyanurate forming catalyst was added. Two hours later, when the increase in the refractive index of the reaction solution reached 0.010, 0.20 g of an 85% phosphorous aqueous solution (6 times mol relative to the catalyst) was added to stop the reaction. When the NMR of the reaction solution was measured, the production ratio of allophanate groups and isocyanurate groups was 0:
It was 100. Then, in the same manner as in Synthesis Example 2, H
The DI was removed. The obtained polyisocyanate composition was a transparent liquid and had a yield of 115 g and a viscosity of 1300 mP.
a. The s and NCO content was 23.2%. Data such as molecular weight are shown in Table 1.

[0067]

Examples 1 to 4 and Comparative Examples 1 to 2 Using the base polyol composition obtained in Synthesis Example 1 and the curing agent composition obtained in Synthesis Examples 2 to 7, the molar ratio of isocyanate group / hydroxyl group was 1 /. 1
Was adjusted so that Solvesso 100 as a solvent
(Axon Chemical Co., Ltd. aromatic solvent, aromatic content 99.0%) was used to adjust the solid content to 70%, and the viscosity of the paint was measured as an index of high solidification. The results are shown in Table 2. In Table 2, the viscosity is 400
mPa. s or less is ⊚, 400 to 500 mPa. s is ○,
500-600 mPa. s is Δ, 600 mPa.s. When it exceeds s, it is indicated by a symbol x.

As an index of curability, the gel fraction at the initial stage of curing was measured. After coating with air spray to a film thickness of about 50 μm, the gel fraction was measured when dried at 20 ° C. for 1 day. The results are shown in Table 2. In Table 2, the gel fraction of 40% or more is ◎, and 30 to 40%.
Is indicated by O, 30-20% by Δ, and less than 20% by X. Apply air spray to a white painted aluminum plate to a film thickness of about 50 microns, and then at 20 ℃
After drying for one day, a scratch resistance test was conducted. The results are shown in Table 2. When the gloss retention rate is 70% or more, it is ◯, 70
.About.60% was designated as .DELTA.

[0069]

Examples 5 to 8 and Comparative Examples 3 to 4 The curing agent compositions obtained in Synthesis Examples 2 to 7 and automotive acrylic polyol (trade name: Setalux 1767VV-65, manufactured by Akzo Nobel, Inc., number average molecular weight = 2500, hydroxyl value = 150 mgKOH / g (relative to resin content) was prepared so that the molar ratio of isocyanate group / hydroxyl group would be 1/1. Solvesso 100 was added as a solvent, and the solid content was 6
The viscosity was adjusted to 7.5%, and the viscosity of the paint was measured as an index of high solidification. The results are shown in Table 3. In Table 3, the viscosity is 750 mPa.s. s or less is ⊚, 750 to 900 mPa.s.
s is ○, 900 to 1050 mPa.s. s is △, 1050m
Pa. When it exceeds s, it is indicated by a symbol x.

As an index of curability, the gel fraction at the initial stage of curing was measured. After coating with air spray to a film thickness of about 50 μm, the gel fraction was measured when dried at 20 ° C. for 1 day. The results are shown in Table 3. In Table 3, the gel fraction of 85% or more is ◎, and 80 to 85%.
Is marked with ◯, and less than 80% is marked with x. A white-painted aluminum plate was coated with air spray to a film thickness of about 50 μm, dried at 20 ° C. for 7 days, and then subjected to a scratch resistance test. The results are shown in Table 3. When the gloss retention rate is 90% or more, it is O, 70 to 90% is Δ, and 70% or less is X.

[0071]

[Table 1]

[0072]

[Table 2]

[0073]

[Table 3]

[0074]

The high solid coating composition of the present invention uses a base polyol containing a low molecular weight acrylic polyol or polyester polyol and a low-viscosity, high-functional polyisocyanate composition. Moreover, the solid content of the coating composition can be increased, and the amount of the organic solvent used can be reduced. The obtained coating film has the features of not only good appearance and excellent weather resistance but also excellent scratch resistance. Therefore, the high-solid coating composition of the present invention is a high-solid coating composition that can be used for automobiles, constructions, home appliances, and information devices such as personal computers and mobile phones. In particular, it is suitable for coating exterior parts of automobiles, which are required to have excellent appearance, weather resistance and scratch resistance. Among them, it is suitable as a paint for new car top coating on the body, plastic parts such as door mirrors and wheels, or paint for automobile repair. Furthermore, among them, it is suitable for top clear applications where weather resistance and surface smoothness are required at a very high level.

Continued front page    F-term (reference) 4J038 CG001 CG002 CG141 CG142                       CH121 CH122 DD001 DD002                       DD041 DD042 DG111 DG112                       DG191 DG192 DG271 DG272                       DG291 DG292 GA03 KA06                       MA14 NA01 NA11 PC02 PC08

Claims (7)

[Claims] 1. (a) Number average molecular weight of 500 to 10,000
Of the main component polyol composition containing the acrylic polyol or the polyester polyol, and (b) at least one kind of diisocyanate selected from aliphatic diisocyanate and alicyclic diisocyanate as raw materials, and the content of components having a molecular weight of 700 or less is 20 to 60 mass%, the ratio of the weight average molecular weight to the number average molecular weight is 1.2 to 5.0, 25
Viscosity of polyisocyanate composition at ° C (unit: mP
a. s) and the number average functional group number of isocyanate groups represented by the following formula: a curing agent composition containing a polyisocyanate composition having an allophanate group, a viscosity (mPa.
s) / Number average functional group number ≦ 240. 2. The high solid coating composition according to claim 1, wherein the nonvolatile content at the time of coating is 65% by mass or more. 3. The high solid coating composition according to claim 1, wherein the number average molecular weight of the base polyol composition is 500 to 8000. 4. A polyisocyanate composition having a molar ratio of allophanate groups to isocyanurate groups of 100/0 to 7
The high solid coating composition according to any one of claims 1 to 3, which is in a range of 5/25. 5. The polyisocyanate composition, wherein at least one diisocyanate selected from an aliphatic diisocyanate and an alicyclic diisocyanate, and a monohydric alcohol and a polyhydric alcohol are used as raw materials. The high-solids coating composition described. 6. A car body or a plastic part for a car coated with the high solid coating composition according to any one of claims 1 to 5. 7. The automobile body or plastic parts for automobiles according to claim 6, wherein the high-solid coating composition is a top clear coating composition.