JP2019163428A - Polyisocyanate composition and coating composition including the same - Google Patents

Abstract

To provide a polyurethane resin composition that can express scratch resistance even when using general acrylic polyols, and also has excellent weather resistance and adhesion, and a coating composition.SOLUTION: A polyisocyanate composition contains a polyisocyanate obtained by urethanization of a diol having a cyclic group with a molecular weight of 300 or less and HDI, and a nurate type polyisocyanate, in a specific mass ratio.SELECTED DRAWING: None

Description

  The present invention relates to a polyisocyanate composition useful as a curing agent for obtaining a polyurethane resin and a coating composition using the polyisocyanate composition as a curing agent.

  Conventionally, non-yellowing polyisocyanates derived from aliphatic isocyanates such as 1,6-hexamethylene diisocyanate (hereinafter referred to as HDI) are excellent in weather resistance, and are therefore often used in the paint / coating and adhesive fields. It has been. Among them, the polyisocyanate type containing an isocyanurate bond has high chemical and thermal stability, and is particularly excellent in weather resistance, heat resistance, and durability. Therefore, it is widely used depending on its application. Application expansion is expected.

  In recent years, plastic products such as mobile phone cases, personal computer cases, audio equipment, electronic material parts such as touch panels and liquid crystal screens, home appliances such as refrigerators, microwave ovens and washing machines, woodworking products such as furniture, golf clubs, In various fields, such as sports equipment such as tennis rackets, architectural interiors such as floors, sinks and doorknobs, and interiors and exteriors of automobiles, further scratch resistance of these surfaces is required.

  In response to the above requirements, a method of forming a coating film having self-healing performance using a two-component curable polyurethane paint and imparting scratch resistance is known (Patent Documents 1 to 3). Patent Document 1 proposes a coating composition containing a specific polyester polyol, a polyisocyanate, and a tin-based urethanization catalyst as essential components. In Patent Document 2, toughness is further imparted by a resin composition containing, as essential components, a polyisocyanate compound having a specific isocyanate group equivalent and a polyester polyol having a specific range of average Tg, average number of functional groups, and number average molecular weight. It has been proposed to do. Patent Document 3 proposes a coating composition comprising a curing agent mainly composed of an allophanate-modified polyisocyanate containing no isocyanurate group, obtained by reacting a specific polyester polyol with a specific diol compound and an organic diisocyanate. ing.

  However, when acrylic polyol or the like generally used in a field requiring weather resistance is used, there are many cases where the above-mentioned proposal is not sufficient for scratch resistance, and improvement has been demanded.

JP-A 63-86762 JP2012-121984 JP 2006-124610 A

  An object of the present invention is to provide a polyurethane resin composition and a coating composition which can exhibit scratch resistance even when a general acrylic polyol is used, and which are excellent in weather resistance and adhesion.

  As a result of repeated studies, the present inventors can solve the above problems by using a polyisocyanate composition containing a polyisocyanate obtained by urethanation of a specific diol and HDI and a nurate type polyisocyanate. And reached the present invention.

  That is, the present invention includes the following embodiments.

  [1] A urethane reaction product (A) of hexamethylene diisocyanate and a diol having a cyclic group having a molecular weight of 300 or less, and a nurate type polyisocyanate (B) obtained by nitrating hexamethylene diisocyanate (A) ) / (B) = 10/90 to 60/40 (mass ratio).

  [2] The polyisocyanate composition according to [1] above, wherein the diol having a cyclic group is a diol having a cyclohexane ring or a benzene ring.

  [3] The polyisocyanate composition according to the above [1] or [2], wherein the diol having a cyclic group is a diol having two or more cyclic groups.

  [4] A polyurethane resin composition comprising the polyisocyanate composition according to any one of [1] to [3] and a polyol.

  [5] A coating composition comprising the polyurethane resin composition according to [4].

  [6] A coating film obtained from the coating composition according to [5] above.

  According to the present invention, even when a general acrylic polyol is used, a polyisocyanate composition capable of exhibiting scratch resistance and being able to obtain a coating film excellent in weather resistance, and a coating composition using this as a curing agent You can get things.

  The present invention is described in detail below.

  The polyisocyanate composition of the present invention is a mixture containing a urethane reaction product (A) of HDI and a diol having a cyclic group having a molecular weight of less than 300, and a nurate polyisocyanate (B).

  HDI used in the polyisocyanate composition of the present invention is a kind of aliphatic diisocyanate monomer (hereinafter, also simply referred to as aliphatic diisocyanate), and is a diisocyanate compound that does not contain a benzene ring in its structure. Examples of aliphatic diisocyanates include HDI, tetramethylene diisocyanate, pentamethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate, and the like. Can be mentioned. HDI may be used alone or in combination with other aliphatic diisocyanates, or in combination with alicyclic diisocyanates represented by isophorone diisocyanate or norbornene diisocyanate.

  The urethane reaction product (A), which is one of the components of the polyisocyanate composition of the present invention, is obtained by urethanization of the hydroxyl group of diol and the isocyanate group of aliphatic diisocyanate. It is shown in the formula.

[Wherein R ₁ represents a hexamethylene group. R ₂ represents a diol residue containing a cyclic group. ].

  The diol having a cyclic group used in the urethane reaction product (A) of the present invention has a molecular weight of less than 300. A compound having a cyclic group such as a cyclohexyl ring, a benzene ring, or a naphthalene ring in the molecular skeleton is preferable.

  Examples of such a compound having a cyclic group include cyclohexanediol, cyclohexanedimethanol, bis (β-hydroxyethyl) benzene, naphthalenediethanol, etc. Examples of compounds containing a plurality of cyclic structures include 2,2 ′ -Bis (4-hydroxycyclohexyl) propane, isosorbide, etc. are mentioned. Especially, an alicyclic group is preferable from the surface of a weather resistance, and what contains multiple cyclic structures is more preferable.

  The nurate polyisocyanate (B), which is another constituent of the polyisocyanate composition of the present invention, contains an isocyanurate group in which diisocyanate monomers are cyclopolymerized with each other, and is represented by the following formula. This is a polyisocyanate having an isocyanurate group which is trimerized, trimerized or pentamerized.

[Wherein R ₁ represents a hexamethylene group. ].

  The mass ratio of the urethane reaction product (A) and the nurate polyisocyanate (B) contained in the polyisocyanate composition of the present invention is in the range of (A) / (B) = 10/90 to 60/40. It is. If the urethane reaction product is less than the lower limit value, sufficient scratch resistance may not be exhibited. If the urethane reaction product is more than the upper limit value, the weather resistance may be impaired.

  Next, the specific manufacturing method of a polyisocyanate composition is demonstrated.

  In the first step, an organic diisocyanate and a diol containing a cyclic group are charged in an amount in which the isocyanate group is excessive with respect to the hydroxyl group, and urethanized in the presence or absence of an organic solvent to produce an isocyanate group-terminated prepolymer. Polymer I is produced. Here, as a standard of the urethanization reaction, the presence or absence of completion is judged by the isocyanate group content and the refractive index increase value by the neutralization titration method.

  In the first step, the reaction proceeds under nitrogen gas or a dry air stream.

  Here, the “amount of excess isocyanate group” in the first step means that the molar ratio of the isocyanate group of the organic diisocyanate to the hydroxyl group of the monool is 3 to 70 in terms of R = isocyanate group / hydroxyl group when the raw materials are charged. It is preferable to charge so that it may become, and it is still more preferable to charge so that it may become R = 5-35. When the molecular weight is less than the lower limit, the molecular weight of the urethane reaction product becomes high, and handling may be deteriorated by increasing the viscosity. When the upper limit is exceeded, the product yield decreases, which may lead to a decrease in productivity.

  Moreover, 20-150 degreeC is preferable and, as for the reaction temperature of the urethanation reaction of this invention, 60-130 degreeC is more preferable. In the urethanization reaction, a known urethanization catalyst can be used. For example, organic metal compounds such as dibutyltin diacetate, dibutyltin dilaurate and dioctyltin dilaurate, organic amines such as triethylenediamine and triethylamine, and salts thereof Etc. These catalysts can be used alone or in combination of two or more.

  The reaction time of the urethanization reaction varies depending on the presence or absence of the catalyst, the type, and the temperature, but is generally within 10 hours, preferably 1 to 5 hours is sufficient.

  In the production of the urethane reaction product, a method of performing the reaction without including an organic solvent or a method of performing the reaction in the presence of the organic solvent is appropriately selected.

  When the reaction is performed in the presence of an organic solvent, an organic solvent that does not affect the reaction can be used. Examples of the organic solvent include aliphatic hydrocarbons such as octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, ketones such as methyl isobutyl ketone and cyclohexanone, esters such as butyl acetate and isobutyl acetate, ethylene glycol Ethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, glycol ether esters such as ethyl-3-ethoxypropionate, ethers such as dioxane, halogens such as methylene iodide and monochlorobenzene And polar aprotic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, hexamethylphosphonilamide and the like. These solvents can be used alone or in combination of two or more.

  The organic solvent used in the reaction is removed simultaneously with the removal of free organic diisocyanate in the next second step.

  In the purification step of the second step, free unreacted organic diisocyanate present in the reaction mixture is removed by thin film distillation or extraction with an organic solvent at 120 to 150 ° C., for example, under a high vacuum of 10 to 100 Pa. By the method, the residual unreacted organic diisocyanate residual content is adjusted to 1% by mass or less. In addition, when the residual content rate of organic diisocyanate exceeds an upper limit, there exists a possibility of causing the generation | occurrence | production of an odor and the fall of storage stability.

  The urethane reaction product (A) obtained by purification can be converted to a blocked isocyanate using a known blocking agent for the purpose of extending the pot life or making the coating composition one component. As a result, the blocked polyisocyanate is inactive at room temperature, but when heated, the blocking agent dissociates, and the isocyanate group is activated again, thereby causing a potential function to react with the active hydrogen group. Can be added.

  The blocking agent that can be used in the present invention is a compound having one active hydrogen in the molecule, for example, an alcohol, alkylphenol, phenol, active methylene, mercaptan, acid amide, acid imide, There are imidazole, urea, oxime, amine, imide, and pyrazole compounds.

  The urethane reaction product thus obtained has a number average molecular weight of preferably 400 to 2000, more preferably 500 to 1000, obtained from gel permeation chromatography measurement (hereinafter referred to as GPC measurement or simply GPC).

  The urethane reaction product (A) obtained by a series of reactions can be made into the polyisocyanate composition of the present invention by mixing with the nurate type polyisocyanate (B). The mass ratio of the urethane reaction product (A) and the nurate polyisocyanate (B) is (A) / (B) = 10/90 to 60/40, preferably 30/70 to 50/50.

  In addition, as a nurate type polyisocyanate (B), the commercial item containing a nurate type polyisocyanate can be used. Examples of such commercially available products include Coronate HX, Coronate HXR, Coronate HXLV (all manufactured by Tosoh Corporation) and the like.

  Furthermore, the polyisocyanate composition obtained above can obtain the coating composition of the present invention by blending a polyol.

  Here, the polyol used in the coating composition of the present invention is not particularly limited, but is a compound containing an active hydrogen group as a reactive group with an isocyanate group, such as a polyester polyol, a polyether polyol, Polycarbonate polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, fluorine-based polyols, transesterification products of two or more polyols, and hydroxyl-terminated prepolymers that have undergone a urethanization reaction with polyisocyanates are preferably used. These can also be used as one kind or a mixture of two or more kinds.

<Polyester polyol>
Examples of the polyester polyol include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, β-diethylsuccinic acid, maleic acid, fumaric acid and other dicarboxylic acids or these One or more anhydrides such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9 Nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer One or more kinds of low molecular weight polyols having a molecular weight of 500 or less such as acid diol, ethylene oxide or propylene oxide adduct of bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, and the like And those obtained from the polycondensation reaction. Also, lactone polyester polyols obtained from ring-opening polymerization of cyclic ester (so-called lactone) monomers such as ε-caprolactone, alkyl-substituted ε-caprolactone, δ-valerolactone, and alkyl-substituted δ-valerolactone can be exemplified. Furthermore, a polyester-amide polyol obtained by replacing a part of the low molecular polyol with a low molecular polyamine such as hexamethylene diamine, isophorone diamine, monoethanolamine, or a low molecular amino alcohol can also be used.

<Polyether polyol>
Examples of the polyether polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, Neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc. Low molecular weight All compounds or compounds having 2 or more, preferably 2 to 3 active hydrogen groups such as ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, low molecular weight polyamines such as xylylenediamine, etc. are started. As an agent, polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, etc., or alkyl glycidyl ethers such as methyl glycidyl ether, aryl glycidyl ethers such as phenyl glycidyl ether And polyether polyols obtained by ring-opening polymerization of cyclic ether monomers such as tetrahydrofuran.

<Polycarbonate polyol>
Examples of the polycarbonate polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neo Pentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide or propylene oxide adduct of bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, bird One or more kinds of low molecular polyols such as tyrolpropane and pentaerythritol, dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, diphenyl carbonate, dinaphthyl carbonate, dianthryl carbonate, di Examples thereof include those obtained from a dealcoholization reaction or a dephenol reaction with diaryl carbonates such as phenanthryl carbonate, diindanyl carbonate, and tetrahydronaphthyl carbonate.

  Moreover, the polyol obtained by transesterification of polycarbonate polyol, polyester polyol, and low molecular polyol can also be used suitably.

<Polyolefin polyol>
Examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene.

<Acrylic polyol>
Examples of the acrylic polyol include acrylic acid ester and / or methacrylic acid ester (hereinafter referred to as (meth) acrylic acid ester), acrylic acid hydroxy compound and / or methacrylic acid having at least one hydroxyl group in the molecule that can be a reaction point. Examples thereof include those obtained by copolymerizing an acrylic monomer using a thermal compound, a light energy such as an ultraviolet ray or an electron beam, and the like with a hydroxy compound (hereinafter referred to as a (meth) acrylic acid hydroxy compound) and a polymerization initiator.

<(Meth) acrylic acid ester>
Examples of (meth) acrylic acid esters include alkyl esters having 1 to 20 carbon atoms. Examples of such (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth Alkyl (meth) acrylates such as hexyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate Esters; esters of (meth) acrylic acid such as cyclohexyl (meth) acrylate with alicyclic alcohols; (meth) acrylic acid aryl esters such as phenyl (meth) acrylate and benzyl (meth) acrylate it can. Such (meth) acrylic acid esters may be used alone or in combination of two or more.

<(Meth) acrylic acid hydroxy compound>
As the (meth) acrylic acid hydroxy compound, for example, it has at least one hydroxyl group in the molecule which can be a reaction point with polyisocyanate. Specifically, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate And hydroxy hydroxy compounds such as 4-hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, and pentaerythritol triacrylate. Also, hydroxy methacrylate compounds such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethylpropyl methacrylate, pentaerythritol trimethacrylate, and the like can be given. These (meth) acrylic acid hydroxy compounds may be used alone or in combination of two or more.

<Silicone polyol>
Examples of the silicone polyol include a vinyl group-containing silicone compound obtained by polymerizing γ-methacryloxypropyltrimethoxysilane and the like, and α, ω-dihydroxypolydimethylsiloxane having at least one terminal hydroxyl group in the molecule, α, ω- Mention may be made of polysiloxanes such as dihydroxypolydiphenylsiloxane.

<Castor oil-based polyol>
Examples of the castor oil-based polyol include linear or branched polyester polyols obtained by a reaction between a castor oil fatty acid and a polyol. Dehydrated castor oil, partially dehydrated castor oil partially dehydrated, and hydrogenated castor oil added with hydrogen can also be used.

<Fluorine-based polyol>
As a fluorine-type polyol, the linear or branched polyol obtained by the copolymerization reaction of a fluorine-containing monomer and the monomer which has a hydroxyl group as an essential component can be mentioned, for example. Here, the fluorine-containing monomer is preferably a fluoroolefin, for example, tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, trifluoromethyl trifluoroethylene. Is mentioned. Examples of the monomer having a hydroxyl group include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and cyclohexanediol monovinyl ether, hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether, and hydroxyalkyl vinyl crotonates. Examples thereof include monomers having a hydroxyl group, such as hydroxyl group-containing vinyl carboxylate or allyl ester.

  The polyol preferably has an active hydrogen group number (average functional group number) in one molecule of 1.9 to 6.0. When the number of active hydrogen groups is less than the lower limit, the physical properties of the coating film may be reduced. Moreover, when exceeding an upper limit, there exists a possibility that adhesiveness may fall.

  Moreover, it is preferable that the number average molecular weight of a polyol exists in the range of 750-50000. If it is less than the lower limit, the adhesion may be reduced, and if it exceeds the upper limit, the solubility in a low-polar organic solvent may be lowered or the adhesion may be lowered.

  Further, the proportion of the polyisocyanate composition of the two-component coating composition and the polyol is not particularly limited, but the molar ratio of the isocyanate group in the isocyanate composition to the hydroxyl group in the polyol is R = It is preferable to mix so that it may become 0.5-2.5 by an isocyanate group / hydroxyl group. If it is less than the lower limit, the hydroxyl group becomes excessive, which may cause a decrease in adhesion. Moreover, there exists a possibility that a crosslinking density may fall and durability and the mechanical strength of a coating film may fall. When the upper limit is exceeded, the isocyanate group becomes excessive and reacts with moisture in the air, which may cause swelling of the coating film and a decrease in adhesion.

  Moreover, as an organic solvent used as a diluting solvent, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate, butyl acetate and cellosolve, alcohols such as butanol and isopropyl alcohol, toluene, xylene, From the group consisting of hydrocarbons such as cyclohexane, mineral spirits, naphtha and the like, it can be appropriately selected and used according to the purpose and application. These solvents may be used alone or in combination of two or more.

  In addition, the two-component coating composition can use a known urethanization catalyst as appropriate in consideration of pot life, curing conditions, working conditions, and the like. Specifically, organic metal compounds such as dibutyltin diacetate, dibutyltin dilaurate and dioctyltin dilaurate, organic amines such as triethylenediamine and triethylamine, and salts thereof are selected and used. These catalysts can be used alone or in combination of two or more.

  In addition, the curing conditions of the two-component coating composition are not particularly limited, but the curing temperature is -5 to 120 ° C, the humidity is 10 to 95% RH, and the curing time is 0.5 to 168 hours. Preferably there is.

  In the two-component coating composition obtained by the present invention, for example, an antioxidant such as 2,6-di-tert-butyl-4-methylphenol, an ultraviolet absorber, a pigment, a dye, Additives such as a solvent, a flame retardant, a hydrolysis inhibitor, a lubricant, a plasticizer, a filler, an antistatic agent, a dispersant, a catalyst, a storage stabilizer, a surfactant, and a leveling agent can be appropriately blended.

  In addition, the two-component coating composition obtained by the present invention is applied onto the surface of an adherend by a known method such as spraying, brushing, dipping, or coater to form a coating film.

  The adherend is not particularly limited, and is stainless steel, phosphated steel, zinc steel, iron, copper, aluminum, brass, glass, slate, acrylic resin, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin. , Polybutylene phthalate resin, polystyrene resin, AS resin, ABS resin, polycarbonate-ABS resin, 6-nylon resin, 6,6-nylon resin, MXD6 nylon resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyurethane resin, phenol resin , Melamine resin, polyacetal resin, chlorinated polyolefin resin, polyolefin resin, polyamide resin, polyether ether ketone resin, polyphenylene sulfide resin, NBR resin, chloroprene resin, SBR resin, SEB An adherend formed of a material such as a resin, an olefin resin such as polyethylene or polypropylene that has been subjected to corona discharge treatment or other surface treatment, or a coat layer that can be formed on the surface of the adherend. A kimono can be used.

  Since the film thickness of the coating film formed on the adherend surface layer is excellent in recoatability and durability, a film thickness of at least 10 μm may be formed on the adherend. When the film thickness is less than 10 μm, the durability is lowered, and there is a possibility that the coating film is torn by impact.

  Since the polyisocyanate composition of the present invention has a very low viscosity, when it is a two-component coating composition, high solid differentiation is possible, and organic solvents can be reduced.

  As described above, the polyisocyanate composition and the two-component paint composition of the present invention are suitably used for automotive paint applications.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

<Synthesis of polyisocyanate composition>
<Example 1>
In a 4-liter flask having a capacity of 1 liter equipped with a stirrer, a thermometer, a condenser tube, and a nitrogen gas introduction tube, 875 g of HDI (manufactured by Tosoh Corporation, NCO content: 49.9% by mass) and hydrogenated bisphenol A (Maruzen) 125 g (manufactured by Petrochemical Co., Ltd., hereinafter referred to as “HBPA”) were charged, and these were heated to 100 ° C. with stirring, and urethanated until reaching a predetermined reaction conversion rate. Here, excess HDI was removed from the reaction product by thin-film distillation (conditions: 140 ° C., 0.04 kPa) to obtain 290 g of polyisocyanate C-1.

  100 g of polyisocyanate C-1 obtained by the above operation was mixed with coronate HXLV (polyisocyanurate, manufactured by Tosoh Corporation, NCO content: 23.1% by mass, hereinafter referred to as C-HXLV) at a ratio of 900 g, 1000 g of polyisocyanate composition P-1 was obtained.

<Examples 2-3>
Under the conditions shown in Table 2, C-1 and C-HXLV were mixed to obtain polyisocyanate compositions P-2 and P-3.

<Comparative Examples 1-2>
Under the conditions shown in Table 3, C-1 and C-HXLV were mixed to obtain polyisocyanate compositions P-4 and P-5.

<Comparative Example 3>
In a 4-liter flask having a capacity of 1 liter equipped with a stirrer, a thermometer, a condenser tube, and a nitrogen gas inlet tube, 950 g of HDI and 50 g of 1,3-butylene glycol (KH Neochem, hereinafter referred to as 1,3-BG) Were heated to 100 ° C. with stirring, and urethanated until a predetermined reaction conversion rate was reached. Here, excess HDI was removed from the reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa) to obtain 230 g of polyisocyanate C-2.

  100 g of polyisocyanate C-2 obtained by the above operation was mixed with 900 g of C-HXLV to obtain 1000 g of polyisocyanate composition P-6.

<Comparative Examples 4-5>
Under the conditions shown in Table 3, C-2 and C-HXLV were mixed to obtain polyisocyanate compositions P-7 and P-8.

<Comparative Example 6>
HDI (940 g) and 1,4-cyclohexanedimethanol (manufactured by Nagase Sangyo Co., Ltd., hereinafter referred to as CHDM) are charged into a 1-liter four-necked flask equipped with a stirrer, thermometer, cooling pipe, and nitrogen gas introduction pipe, These were heated to 40 ° C. with stirring, and urethanization reaction was performed for 1 hour. Thereafter, the temperature is raised to 60 ° C., and 0.1 g of zirconyl octylate (Daiichi Rare Element Chemical Co., Ltd.), which is an allophanate catalyst, is added to the reaction solution until a predetermined reaction conversion rate is reached at 110 ° C. After the reaction, 0.11 g of acidic phosphate ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) as a reaction terminator was added, and a termination reaction was performed at 60 ° C. for 1 hour. Here, excess HDI was removed from the reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa) to obtain 320 g of polyisocyanate C-3.

  100 g of polyisocyanate C-3 obtained by the above operation was mixed with 900 g of C-HXLV to obtain 1000 g of polyisocyanate composition P-9.

<Comparative Examples 7-8>
Under the conditions shown in Table 3, C-3 and C-HXLV were mixed to obtain polyisocyanate compositions P-10 and P-11.

<Comparative Example 9>
Commercially available Tosoh polyisocyanurate C-HXLV was used.

<Preparation of two-component coating composition>
As shown in Tables 4 and 5, the paint blending liquid for scratch resistance evaluation is blended with a polyol and a polyisocyanate composition so that R (molar ratio of isocyanate group / hydroxyl group) = 1.0, and further an organic solvent. The two-component coating composition (S-1 to S-12) was prepared so that the solid content was 50% by mass (unit: g). Here, acrylic polyol (trade name: ACRYDIC 49-394-IM, hydroxyl value: 25 mg KOH / g, solid content: 50% by mass, manufactured by DIC) is used as the polyol, and butyl acetate is used as the organic solvent. And titanium oxide CR-90 (manufactured by Ishihara Sangyo) was used as the pigment.

<Preparation of two-component coating composition (weather resistance, adhesion)>
As shown in Tables 6 and 7, the paint blending solution for weather resistance and adhesion evaluation was blended with polyol and polyisocyanate composition so that R (isocyanate group / hydroxyl molar ratio) = 1.0, Further, a two-component coating composition (S-1 to S-12) was prepared so that the solid content was 50% by mass with an organic solvent (the unit of the blending amount was g). Here, acrylic polyol (trade name: Acrydic A-801, hydroxyl value: 50 mgKOH / g, solid content: 50% by mass, manufactured by DIC) is used as the polyol, and butyl acetate is used as the organic solvent. The pigment was prepared using titanium oxide CR-50 (Ishihara Sangyo).

<Coating method and test piece preparation>
The prepared two-component paint composition is defatted with methyl ethyl ketone (JIS G3141, trade name: SPCC-SB, treatment method: PF-1077, manufactured by Partec Co., Ltd.) using an applicator so as to have an arbitrary film thickness. Applied. Thereafter, heat treatment was performed in a dryer at a temperature of 60 ° C. for 1 hour, followed by curing for 7 days in an environment at a temperature of 23 ° C. and a relative humidity of 50% to obtain coating films S-1 to S-12.

<Scratch resistance evaluation>
The indentation hardness of a coating film (film thickness after drying of about 20 μm) prepared from the paint obtained by the formulation shown in Tables 4 and 5 was measured by a scratch resistance test under the following conditions. The results are shown in Tables 8 and 9. An evaluation A is good.
Test equipment: Fischer scope HM2000 (Fischer Instruments)
・ Indenter: Vickers diamond ・ Test temperature: 25 ℃
<Scratch resistance evaluation criteria>
The indentation hardness values were classified according to the following criteria.
・ 125 N / mm ² or more: (Evaluation) A
· 110N / mm ² or more ~125N / mm ² less than :( evaluation) B
-Less than 110 N / mm < ² >: (Evaluation) C.

<Weather resistance evaluation>
An accelerated weather resistance test was performed on the coating film (film thickness after drying of about 20 μm) prepared from the paints obtained with the formulations shown in Tables 6 and 7 under the following conditions.
・ Test equipment: QUV (manufactured by Q-LAB)
・ Lamp: EL-313
・ Illuminance: 0.59 w / m2
・ Λmax: 313 nm
1 cycle: 12 hours [UV irradiation: 8 hours (temperature 70 ° C.), condensation: 4 hours (temperature 50 ° C.)]
Test time: 576 hours <Weather resistance evaluation criteria>
According to JIS Z8741, the glossiness at 60 ° was measured with a gloss meter (product name: Micro-Gloss, manufactured by BYK), and the gloss retention was calculated. The gloss retention was determined by the following formula. The results are shown in Tables 8 and 9. An evaluation A is good.

Gloss retention (%) = 100 × Glossiness after weathering test ÷ Initial glossiness (Formula)
・ 80% or more: (Evaluation) A
・ 70% to less than 80%: (Evaluation) B
-Less than 70%: (Evaluation) C.

<Preparation of metallic base paint for adhesion evaluation>
Aqueous acrylic polyol (product name: Bernock WE-303, manufactured by DIC) 25.0 g, rheology control agent (product name: BYK-425, manufactured by BYK) 0.5 g, antifoaming agent (product name: BYK-012) 0.5 g of BYK), 1.0 g of a wetting and dispersing agent (product name: DISPERBYK-192, manufactured by BYK) and 2.0 g of aluminum paste (product name: Alpaste WXM5660, manufactured by Toyo Aluminum Co., Ltd.) The viscosity was adjusted by adding 15.0 g of methanol.

<Adhesion evaluation>
The prepared metallic base paint is applied to a steel plate (JIS G3141, trade name: SPCC-SB, treatment method: PF-1077, manufactured by Partec Co.) degreased with methyl ethyl ketone by spraying so that the film thickness after drying is about 30 μm. did. Thereafter, it was cured for 30 minutes in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and heat-treated for 30 minutes at 60 ° C. Further, the two-component coating composition prepared in Table 4 was applied on the steel plate coated with the metallic base using an applicator, pre-dried at room temperature for 10 minutes, and then heat-treated in a dryer at 90 ° C. for 30 minutes. Then, heat treatment was performed for 10 hours at 80 ° C. to obtain a coating film.
<Adhesion evaluation criteria>
The obtained coating film was subjected to an adhesion test by a cross-cut method according to JIS K5600-5-6. The results are shown in Tables 8 and 9. An evaluation A is good.
・ Classification 0 to 1: A
・ Classification 2 to 5: B

Claims (6)

  A urethane reaction product (A) of hexamethylene diisocyanate and a diol having a cyclic group having a molecular weight of 300 or less, and a nurate-type polyisocyanate (B) obtained by nucleating hexamethylene diisocyanate, (A) / ( B) = polyisocyanate composition characterized by containing in the range of 10/90 to 60/40 (mass ratio).   The polyisocyanate composition according to claim 1, wherein the diol having a cyclic group is a diol having a cyclohexane ring or a benzene ring.   The polyisocyanate composition according to claim 1 or 2, wherein the diol having a cyclic group is a diol having two or more cyclic groups.   A polyurethane resin composition comprising the polyisocyanate composition according to any one of claims 1 to 3 and a polyol.   A coating composition comprising the polyurethane resin composition according to claim 4.   A coating film obtained from the coating composition according to claim 5.