JP2019089915A - Polyisocyanate composition and two-liquid coating composition including the same - Google Patents

Abstract

To provide a polyisocyanate composition having excellent metallic glossiness (flip-flop property) when used for a top coat of a multilayer coat while maintaining thermal stability and weather resistance irrespective of low viscosity, and a coating composition prepared with the same as a curing agent.SOLUTION: The present invention provides a polyisocyanate composition containing allophanate modified polyisocyanate obtained from hexamethylene diisocyanate and monoalcohol, where the allophanate modified polyisocyanate has an average degree of polymerization of 1.5 or less.SELECTED DRAWING: None

Description

  The present invention relates to a low viscosity polyisocyanate composition useful as a curing agent for obtaining a polyurethane resin and the like, and a two-component coating composition using the same as a curing agent.

  Conventionally, in the field of paints, coatings and adhesives, non-yellowing polyisocyanates derived from aliphatic isocyanates such as 1,6-hexamethylenediisonate (hereinafter referred to as HDI) are excellent in weatherability, but Among them, polyisocyanate type containing an isocyanurate bond is widely used depending on the application because it is high in chemical and thermal stability and is particularly excellent in weather resistance, heat resistance and durability. Deployment is expected.

  When this type having an isocyanurate bond is used as a curing agent, its handling is poor because of its high viscosity, and it may be used after being diluted with an organic solvent or the like. In recent years, awareness of environmental load reduction has increased, and in order to reduce the amount of organic solvent used, it is required to lower the viscosity of polyisocyanate used as a curing agent. By lowering the viscosity of the polyisocyanate, the handleability at the time of coating is improved, and the amount of use of the organic solvent used in the coating composition can be reduced.

  As a technique for reducing the viscosity of polyisocyanate, polyisocyanate having a uretdione bond has been proposed. Polyisocyanate having a uretdione bond can realize low viscosity, but there is a problem that the thermal stability and the weather resistance are poor (Patent Documents 1 and 2).

  In addition, polyisocyanates having allophanate bonds obtained by reacting HDI with aliphatic monoalcohols have also been proposed (Patent Document 3). The allophanate group is superior to the uretdione group in thermal stability and weatherability. However, polyisocyanates containing allophanate bonds also have problems such as poor chemical and thermal stability and poor weather resistance as compared to the aforementioned isocyanurate bonds.

  In addition, polyisocyanates containing allophanate bonds and isocyanurate bonds obtained by reacting HDI with monools having 11 to 20 carbon atoms are disclosed (Patent Document 4). However, the amount of isocyanate groups contained in one molecule (hereinafter, the isocyanate content) was low. The higher the isocyanate content, the higher the concentration of urethane bonds obtained by reaction with the hydroxyl groups in the polyol of the overall coating composition in the coating composition comprising the combination with the polyol. Since this leads to the improvement of the mechanical properties of the urethane coating, a polyisocyanate having a high isocyanate content is desired.

Unexamined-Japanese-Patent No. 5-32759 JP, 2013-224350, A JP 2003-137966 A JP 2012-255101 A

  The present invention has been made in view of the above-described background art, and its object is to provide a metallic gloss when used as a top coat of a multilayer coating while maintaining thermal stability and weather resistance while having low viscosity. An object of the present invention is to provide a polyisocyanate composition having excellent properties (flip flop properties) and a coating composition using the same as a curing agent.

  As a result of repeated studies, the present inventors have found that the above-mentioned problems can be solved by aliphatic polyisocyanate obtained by causing allophanate reaction of HDI and monoalcohol at a certain degree of polymerization or less, and reached the present invention .

  That is, the present invention includes the following embodiments.

  [1] A polyisocyanate composition comprising an allophanate-modified polyisocyanate obtained from hexamethylene diisocyanate and a monoalcohol, wherein the average degree of polymerization of the allophanate-modified polyisocyanate is 1.5 or less. Polyisocyanate composition.

  [2] The polyisocyanate composition as described in [1] above, wherein the carbon number of the monoalcohol is 1 to 3.

  [3] The polyisocyanate composition according to the above [1] or [2], which comprises a polyisocyanurate.

  [4] In the polyisocyanate composition according to any one of the above [1] to [3], the number of moles of allophanate group / the total number of moles of isocyanurate group and uretdione group = 100/0 to 10/90 Polyisocyanate composition characterized by the above.

  [5] The polyisocyanate composition as described in any one of [1] to [4] above, wherein the concentration of uretdione group in the polyisocyanate composition is 5 mol% or less.

  [6] A two-part coating composition comprising the polyisocyanate composition according to any one of the above [1] to [5] and a polyol.

  The polyisocyanate composition of the present invention maintains high thermal stability and weather resistance while maintaining low viscosity, secures a high isocyanate content, and is excellent in substrate adhesion and flip-flop properties, and the polyisocyanate composition Can be obtained as a curing agent.

  In addition, because of the characteristics of low viscosity, it is possible to impart permeability to the lower layer coating film such as the intermediate coating and the base layer, and to improve physical properties as a multilayer coating film.

  Hereinafter, the present invention will be described in detail.

  The polyisocyanate composition of the present invention comprises an allophanate-modified polyisocyanate obtained by the allophanate reaction of HDI with a monoalcohol at a certain degree of polymerization or less.

  The isocyanate component used in obtaining the allophanate-modified polyisocyanate of the present invention is HDI, which is an aliphatic isocyanate. As aliphatic isocyanates, in addition to HDI, tetramethylene diisocyanate, pentamethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate Etc. can be mentioned. In the present invention, HDI is used for weather resistance and easiness of industrial availability, but other aliphatic isocyanates mentioned above, alicyclic isocyanates represented by isophorone diisocyanate, norbornene diisocyanate, etc., diphenylmethane diisocyanate, toluene diisocyanate, etc. And aromatic aliphatic isocyanates represented by Xylene diisocyanate may be used in combination without departing from the scope of the present invention.

  Examples of monoalcohols used for obtaining the allophanate-modified polyisocyanate of the present invention include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pen Tanol, isoamyl alcohol, 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, 3,3,5-trimethyl-1-hexanol, 1-tridecanol, 2-tridecanol, 2 -Octyldodecanol, pentadecanol, palmityl alcohol, stearyl alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, trimethylcyclohexanol and the like. Although these monools are not particularly limited, it is preferable to use methanol, ethanol, 1-propanol and 2-propanol which are monoalcohols having 1 to 3 carbon atoms. It is preferable to use a monoalcohol having 1 to 3 carbon atoms because the isocyanate content of the polyisocyanate can be increased.

  The allophanate group generated by the allophanate reaction is obtained by the reaction of another isocyanate group with the urethane group after the hydroxyl group of the monoalcohol and the isocyanate group of HDI react to form a urethane bond, It is shown in the formula. The average degree of polymerization of the allophanate reaction product can be adjusted by the ratio of HDI to monoalcohol.

[In the Formula, R represents a hexamethylene group. R 'represents an alkyl group. ].

The average degree of polymerization of the allophanate-modified polyisocyanate in the present invention is 1.5 or less. The average degree of polymerization in the present invention can be calculated by the following formula based on the result of GPC (gel permeation chromatography).
Average degree of polymerization = (proportion of monomer (mass%) + proportion of dimer (mass%) × 2 + proportion of trimer (mass%) × 3 + proportion of tetramer (mass%) × 4 + polymer Ratio (mass%) x 5) / 100.

  In addition, the ratio of the monomer etc. in this invention used the area of each peak area obtained by GPC, and handled the area and mass of a peak area equally.

  When the average degree of polymerization is set to 1.5 or less, when used as a top coat curing agent for a multilayer coating, the permeability to the primer primer is improved, and the interlayer adhesion when forming a coating is improved. It is possible to obtain a coating film which can be improved and which is also excellent in metallic gloss (flip flop property).

  In order to set the average degree of polymerization to 1.5 or less, the ratio of HDI to monoalcohol may be adjusted, and a special synthesis method is not required.

  Further, the isocyanurate group in the present invention is obtained by cyclopolymerization of hexamethylene diisocyanate monomers with each other, and is represented by the following formula. These are polyisocyanates having trimerized or pentamerized, multimerized isocyanurate groups.

[In the Formula, R represents a hexamethylene group. ].

  Further, the uretdione group in the present invention is a linear polymerization of isocyanate groups and is represented by the following formula. The uretdione body of the present invention refers to a diisocyanate dimer having a uretdione group consisting of two molecules of hexamethylene diisocyanate monomer.

[In the Formula, R represents a hexamethylene group. ].

  The molar ratio of allophanate group, isocyanurate group and uretdione group contained in the polyisocyanate composition of the present invention is in the range of allophanate group / (isocyanurate group + uretdione group) = 100/0 to 10/90. Is preferred. If the molar ratio of allophanate groups is less than the lower limit value, the permeability of the curing agent may be reduced and the adhesion may be impaired.

  The polyisocyanate composition of the present invention preferably contains 5% by mole or less of the uretdione body contained in the total composition of the polyisocyanate. If it is 5 mol% or less, the thermal stability and the weather resistance of the coating film are excellent, and if the amount of uretdione body exceeds 5 mol%, the thermal stability and the weather resistance of the coating film may be deteriorated.

In addition, mol% of uret dione body in this invention is computed from the signal area ratio of < ¹ > H-NMR.

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

  In the first step, an organic diisocyanate and a monoalcohol are charged with an amount such that the isocyanate group is in excess with respect to the hydroxyl group, and the urethane reaction is carried out at 20 to 60 ° C. in the presence or absence of an organic solvent to end isocyanate group. Prepolymer I is prepared. Here, as a standard of the urethanation reaction, the presence or absence of completion is judged by the isocyanate group content by the neutralization titration method and the refractive index increase value.

  In the second step, an allophanatization catalyst is added to the isocyanate group-terminated prepolymer I, and allophanatization is performed at 50 to 150 ° C. until the desired isocyanate group content and molecular weight are reached to obtain an isocyanate group-terminated prepolymer II. Manufacture.

  In the third step, the reaction is terminated by adding a reaction terminator to the isocyanate group-terminated prepolymer II.

  In these first to third steps, the reaction is allowed to proceed under nitrogen gas or a stream of dry air.

  In the fourth step, the isocyanate group-terminated prepolymer II is removed by thin film distillation or solvent extraction until the content of free organic diisocyanate is less than 1% by mass.

  Here, “the amount of the isocyanate group becoming excessive” 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 15 to 75 when R = isocyanate group / hydroxyl group when the raw materials are charged. It is preferable to charge so that it may become and it is further more preferable to charge so that it may be set to R = 20-70. If it is less than the lower limit, the degree of polymerization of the allophanate reaction product becomes high, and there is a possibility that the flip-flop property in forming a coating film may be deteriorated. If the upper limit is exceeded, the product yield may be lowered and productivity may be reduced.

  Here, the flip-flop property in the present invention represents the degree of change in lightness depending on the angle of observation when the coating film is observed at different angles, and the larger the change, the more the flip-flop property. It is a coating film that is high and has high designability.

  Moreover, 20-70 degreeC is preferable and, as for the reaction temperature of the urethanation reaction of this invention, 30-60 degreeC is more preferable. In the urethanization reaction, a known urethanization catalyst can be used. 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.

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

  As the allophanatization catalyst in the second step, the following catalysts may be mentioned.

  Generally as an allophanatization catalyst, what has basicity is preferable, for example, metal salts, such as tin, zinc, lead, bismuth, a zirconium, etc. of alkylcarboxylic acids, such as acetic acid, caproic acid, octylic acid, myristic acid, etc. are mentioned. . Among these, tin and alkyl carboxylic acid are preferable from the viewpoint of reactivity.

  0.001-1.0 mass% is preferable with respect to the total mass of organic diisocyanate and monoalcohol, and, as for the usage-amount of allophanatization catalyst, 0.005-0.1 mass% is more preferable.

  If it is less than the lower limit, the allophanatization reaction does not proceed sufficiently, the amount of urethane group-containing polyisocyanate which is a precursor of polyisocyanate is increased, and the physical properties of the coating film decrease with the decrease of the average number of functional groups, There is a risk that productivity and yield may be reduced. When the content exceeds the upper limit, the amount of polyisocyanate having a molecular weight higher than that of the desired product is increased, which may increase the viscosity and lower the reactivity control.

  Moreover, 50-150 degreeC is preferable and, as for the reaction temperature of allophanatization reaction, 80-120 degreeC is more preferable.

  Further, in the production of polyisocyanate, a method of carrying out the reaction without containing an organic solvent or the like or a method of carrying out the reaction in the presence of an organic solvent may be appropriately selected.

  When the reaction is carried out in the presence of an organic solvent, an organic solvent which does not affect the reaction can be used. Specific 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, Glycol ether esters such as ethylene glycol ethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl 3-ethoxy propionate, ethers such as dioxane, methylene iodide, monochlorobenzene, etc. And a polar aprotic solvent such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphonylamide 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 the free organic diisocyanate in the fourth step.

  The reaction stopping agent in the third step has an action of deactivating the activity of the catalyst, and specifically, an organic acid having an inorganic acid such as phosphoric acid or hydrochloric acid, a sulfonic acid group, a sulfamic acid group, etc. Known compounds such as acids and their esters, acyl halides and the like are used. These reaction terminators can be used alone or in combination of two or more. In addition, addition time is preferable after completion | finish of reaction.

  The addition amount of the reaction terminator varies depending on the type of the reaction terminator and the catalyst used, but it is preferably 0.5 to 10 equivalents of the catalyst, and particularly preferably 0.8 to 5.0 equivalents. When the amount of the reaction terminator is small, the storage stability of the obtained polyisocyanate composition tends to be deteriorated, and when it is too large, the polyisocyanate composition may be colored.

  In the purification step of the fourth step, the free unreacted organic diisocyanate present in the reaction mixture is removed, for example, by thin film distillation at 120 to 150 ° C. under high vacuum of 10 to 100 Pa or extraction with an organic solvent According to the method, the free unreacted organic diisocyanate residual content is made to be 1.0% by mass or less. In addition, when the residual content rate of organic diisocyanate exceeds an upper limit, there exists a possibility of causing generation | occurrence | production of an odor, or the fall of storage stability.

  The polyisocyanate composition obtained by the purification can also be made into a blocked isocyanate using a known blocking agent for the purpose of prolonging the pot life and making the coating composition liquefaction. As a result, the blocked polyisocyanate is inactive at normal temperature, but the heating causes the blocking agent to dissociate and the isocyanate group to be activated again 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, and examples thereof include alcohols, alkylphenols, phenols, active methylenes, mercaptans, acid amides, acid imides, There are imidazole type, urea type, oxime type, amine type, imide type, pyrazole type compounds and the like.

  The polyisocyanate composition obtained by the series of reactions can be mixed with the polyisocyanurate and used. The mixing ratio of polyisocyanate composition to polyisocyanurate (molar ratio of allophanate group / isocyanurate group) is preferably 100/0 to 10/90, more preferably 70/30 to 10/90, and 50/50. 50 to 10/90 is most preferred. If the mixing ratio of allophanate groups is less than 10, adhesion may be reduced.

  Furthermore, the polyisocyanate liquid mixture obtained above can obtain the two-part coating composition of the present invention by blending a polyol.

  Here, the polyol used in the two-pack type paint composition of the present invention is not particularly limited, but it is a compound containing an active hydrogen group as a reactive group with an isocyanate group, and polyester polyol, poly Ether polyols, polycarbonate polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil based polyols, fluorine based polyols, ester-exchanged products of two or more types of polyols, and hydroxyl terminated prepolymers which are urethane-reacted with polyisocyanate etc. They can also be used as a mixture of one or more types.

<Polyester polyol>
Examples of polyester polyols 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 and sebacic acid 1,4-cyclohexyl dicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethyl glutaric acid, α, β-diethyl succinic acid, dicarboxylic acids such as maleic acid and fumaric acid or the like 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 Acid diol, ethylene oxide or propylene oxide adduct of bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol etc. and one or more kinds of low molecular weight polyols having a molecular weight of 500 or less And the like obtained from the condensation polymerization reaction of Other examples include lactone polyesterpolyols 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. Furthermore, polyester-amide polyols obtained by replacing a part of the low molecular weight polyol with a low molecular weight polyamine such as hexamethylene diamine, isophorone diamine, monoethanolamine or the like or a low molecular weight amino alcohol can also be used.

<Polyether polyol>
Moreover, as polyether polyols, for example, 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 Compounds having two or more, preferably two to three, active hydrogen groups such as low molecular weight polyamines such as ethylene glycol, ethylene diamine, propylene diamine, toluene diamine, metaphenylene diamine, diphenylmethane diamine, xylylene diamine, etc. Polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide, or alkyl glycidyl ethers such as methyl glycidyl ether, aryl glycidyl ethers such as phenyl glycidyl ether, cyclic such as tetrahydrofuran The polyether polyol obtained by ring-opening-polymerizing an ether monomer can be mentioned.

<Polycarbonate polyol>
In addition, examples of polycarbonate polyols 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 of low molecular weight polyols such as tyrololpropane 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, What is obtained from the dealcoholization reaction or dephenolation reaction with diaryl carbonates such as phenanthryl carbonate, diindanyl carbonate, tetrahydronaphthyl carbonate and the like can be mentioned.

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

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

<Acryl polyol>
As an acrylic polyol, acrylic acid ester and / or methacrylic acid ester [hereinafter referred to as (meth) acrylic acid ester] and acrylic acid hydroxy compound and / or methacrylic acid having at least one hydroxyl group in the molecule which can be a reaction point A hydroxy compound [hereinafter referred to as (meth) acrylic acid hydroxy compound] and a polymerization initiator may be copolymerized with acrylic monomers using thermal energy, light energy such as ultraviolet light or electron beam, and the like.

<(Meth) acrylic acid ester>
As a (meth) acrylic acid ester, a C1-C20 alkyl ester can be mentioned. Specific examples of such (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (Meth) acrylic acids such as hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate Acid alkyl ester; ester of (meth) acrylic acid with alicyclic alcohol such as cyclohexyl (meth) acrylate; phenyl (meth) acrylate, (meth) acrylic acid aryl ester such as benzyl (meth) acrylate Can. Such (meth) acrylic acid esters may be used alone or in combination of two or more.

<(Meth) acrylic acid hydroxy compound>
The (meth) acrylic acid hydroxy compound has one or more hydroxyl groups in at least the molecule that can be a reaction point with polyisocyanate, and specifically, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, Acrylic acid hydroxy compounds such as 4-hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, pentaerythritol triacrylate and the like can be mentioned. In addition, methacrylic acid hydroxy 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 mentioned. As these (meth) acrylic acid hydroxy compounds, those obtained by combining one or more kinds can be mentioned.

<Silicone polyol>
As silicone polyols, vinyl group-containing silicone compounds obtained by polymerizing γ-methacryloxypropyltrimethoxysilane or the like, and α, ω-dihydroxypolydimethylsiloxanes having at least one terminal hydroxyl group in the molecule, α, ω-dihydroxy Mention may be made of polysiloxanes such as polydiphenylsiloxane.

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

<Fluorinated polyol>
As a fluorine-type polyol, the linear or branched polyol obtained by the copolymerization reaction can be mentioned, for example by using a fluorine-containing monomer and the monomer which has a hydroxyl group as an essential component. Here, as the fluorine-containing monomer, a fluoroolefin is preferable. For example, tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, trifluoromethyltrifluoroethylene Can be mentioned. Further, as a monomer having a hydroxyl group, for example, hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, cyclohexanediol monovinyl ether and the like, hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether, vinyl hydroxyalkyl crotonate And monomers having a hydroxyl group such as hydroxyl group-containing carboxylic acid vinyl 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. If the number of active hydrogen groups is less than the lower limit value, the physical properties of the coating may be degraded. When the content exceeds the upper limit value, the adhesion may be reduced.

  Further, the number average molecular weight of the polyol is preferably in the range of 750 to 50000. If it is less than the lower limit value, the adhesion may be reduced, and if it exceeds the upper limit value, the solubility in the low polar organic solvent may be reduced or the adhesion may be reduced.

  Further, the blending ratio 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 and the hydroxyl group in the polyol is R = isocyanate It is preferable to mix | blend so that it may be set to 0.5-2.5 by group / hydroxyl group. If it is less than the lower limit value, the hydroxyl groups become excessive, which may cause a decrease in adhesion. In addition, the crosslink density may be reduced to reduce the durability and the mechanical strength of the coating. When the content exceeds the upper limit value, the isocyanate group becomes excessive, which may react with moisture in the air, resulting in a swelling of the coating film and a decrease in adhesion accompanying this.

  Moreover, as an organic solvent used as a dilution solvent, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate, n-butyl acetate and cellosolve acetate, alcohols such as butanol and isopropyl alcohol, toluene From the group consisting of hydrocarbons such as xylene, cyclohexane, mineral spirits, naphtha, etc., they 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, as the two-component coating composition, a known urethanization catalyst can be appropriately used in consideration of the pot life, the curing conditions, the 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.

  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. Is preferred.

  In the two-pack type paint composition obtained by the present invention, as required, for example, an antioxidant such as 2,6-di-tert-butyl-4-methylphenol, an ultraviolet light absorber, a pigment, a dye, Additives such as solvents, flame retardants, hydrolysis inhibitors, lubricants, plasticizers, fillers, antistatic agents, dispersants, catalysts, storage stabilizers, surfactants, leveling agents and the like can be appropriately blended.

  In addition, the two-component coating composition obtained by the present invention is applied on the surface of an adherend by a known method such as spray, brush, dip, coater or the like to form a coating.

  Here, the adherend is not particularly limited, and stainless steel, phosphate treated 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, polyetheretherketone resin, polyphenylene sulfide resin, NBR resin, chloroprene resin, SBR resin, SEB An adherend molded from a material such as a resin, an olefin resin such as polyethylene or polypropylene which has been subjected to corona discharge treatment or other surface treatment, or an adherend having a coating layer which can be formed on the surface of the adherend. A garment can be used.

  The film thickness of the coating film formed on the surface of the adherend is excellent in recoatability and durability, so 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 may be broken due to the impact.

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

  In addition, the polyisocyanate composition of the present invention and the two-pack paint composition can be 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
Hexamethylene diisocyanate (Tosoh Corporation, NSO content: 49.9 mass%, hereinafter referred to as HDI) 990 g in a 1-liter four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet pipe 10 g of methanol was charged, and the mixture was heated to 40 ° C. while stirring, and the urethanation reaction was performed for 1 hour. Thereafter, the temperature is raised to 60 ° C., 0.1 g of zirconyl octylate (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.), which is an allophanate conversion catalyst, is added to this reaction liquid, and a predetermined reaction conversion rate is reached at 110 ° C. After the reaction, 0.11 g of acidic phosphoric acid ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) as a reaction terminator was added, and termination reaction was performed at 60 ° C. for 1 hour. Here, excess HDI is removed from the reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa), NCO content 22.4% by mass, viscosity (25 ° C.) 110 mPa · s, free HDI content 0. 112 g of 2% by mass of polyisocyanate C-1 was obtained. The polyisocyanate C-1 was subjected to ¹ H-NMR measurement, and the molar ratio of allophanate group / isocyanurate group / uretdione group was 99/0/1. Further, when measured by GPC, the peaks shown in Table 2 were obtained, and the average degree of polymerization calculated from the area of each peak area by the following formula was 1.47.

<Calculation method>
Average degree of polymerization = (proportion of monomer (71 mass%) + proportion of dimer (18.8 mass%) x proportion of 2 + trimer (4.1 mass%) x 3 + proportion of tetramer 1.2 mass%) × 4 + proportion of multimer (4.2 mass%) × 5) / 100 = 1.47.

100 g of the polyisocyanate C-1 obtained by the above operation and 900 g of Coronate HXR (polyisocyanurate, manufactured by Tosoh Corporation, NCO content: 21.8 mass%, hereinafter referred to as C-HXR) are mixed, 1000 g of polyisocyanate mixed solution P-1 was obtained. The polyisocyanate mixture liquid P-1 was subjected to ¹ H-NMR measurement, and the molar ratio of allophanate group / isocyanurate group / uretdione group was 14/84/2.

<NMR: Measurement of molar ratio of allophanate group, isocyanurate group, uretdione group>
(1) Measuring device: ECX400M (manufactured by JEOL, ¹ H-NMR)
(2) Measurement temperature: 23 ° C
(3) Sample concentration: 0.1 g / 1 ml
(4) Number of integrations: 16
(5) Relaxation time: 5 seconds (6) Solvent: deuterium dimethyl sulfoxide (7) Chemical shift standard: hydrogen atom signal of methyl group in deuterium dimethyl sulfoxide (2.5 ppm)
(8) Evaluation method: signal of hydrogen atom bonded to nitrogen atom of allophanate group around 8.5 ppm, signal of hydrogen atom of methylene group adjacent to nitrogen atom of nurate group around 3.7 ppm, 3.9 ppm The content of the bonding group was determined from the area ratio of the hydrogen atom signal of the methylene group adjacent to the nitrogen atom of the nearby uretdione group.

<GPC: Measurement of Molecular Weight>
(1) Measuring instrument: HLC-8220 (made by Tosoh Corporation)
(2) Column: TSKgel (made by Tosoh Corporation)
・ G3000H-XL
・ G2500H-XL
・ G2000H-XL, G1000H-XL
(3) Carrier: THF (tetrahydrofuran)
(4) Detector: RI (refractive index) detector (5) Temperature: 40 ° C
(6) Flow rate: 1.000 ml / min
(7) Calibration curve: Standard polystyrene (made by Tosoh Corporation)
F-80 (molecular weight: 7.06 × 105, molecular weight distribution: 1.05)
F-20 (molecular weight: 1.90 × 105, molecular weight distribution: 1.05)
F-10 (molecular weight: 9.64 × 104, molecular weight distribution: 1.01)
F-2 (molecular weight: 1.81 × 10 4, molecular weight distribution: 1.01)
F-1 (molecular weight: 1.02 × 10 4, molecular weight distribution: 1.02)
A-5000 (molecular weight: 5.97 × 103, molecular weight distribution: 1.02)
A-2500 (molecular weight: 2.63 × 103, molecular weight distribution: 1.05)
A-500 (molecular weight: 5.0 × 102, molecular weight distribution: 1.14)
(8) Sample solution concentration: 0.5% THF solution.
(9) Assignment of each peak of the GPC chart:
-Allophanate multimer: peak-allophanate tetramer around retention time = 19.9 minutes: peak-allophanate trimer around retention time = 20.4 minutes-peak-allophanate 2 around retention time = 21.1 minutes Mer: peak allophanate monomer around retention time = 22.0 minutes; peak around retention time = 23.2 minutes.

Examples 2-3
C-1 and C-HXR were mixed under the conditions shown in Table 3 to obtain polyisocyanate mixed liquids P-2 and P-3.

Examples 4 and 5
Polyisocyanates C-2 and C-3 were obtained in the same manner as in Example 1 under the conditions shown in Table 1. Under the conditions shown in Table 3, the obtained polyisocyanates C-2 and C-3 and C-HXR were mixed to obtain polyisocyanate mixed solutions P-4 to P-5.

<Comparative Examples 1 to 6>
Under the conditions shown in Table 1, polyisocyanates C-4 and C-5 were obtained in the same manner as in Example 1. Under the conditions shown in Table 3, the obtained polyisocyanates C-4 and C-5 and C-HXR were mixed to obtain polyisocyanate mixed liquids P-6 to P-11.

Comparative Example 7
A commercially available Tosoh polyisocyanurate C-HXR was used.

<Preparation of Two-component Coating Composition>
As shown in Table 4, the compounding amount is such that R (isocyanate group / hydroxyl group molar ratio) = 1.2 is used as the polyol and polyisocyanate mixture, and the solid content becomes 50% by mass with the organic solvent. Thus, a two-component paint composition (S-1 to S-11) was prepared (the unit of the amount is g). Here, as the polyol, acrylic polyol (trade name: Acrydic A-801, hydroxyl value: 50 mg KOH / g, solid content: 50 mass%, manufactured by DIC) is used, and as the organic solvent, butyl acetate is used Prepared.

<Coating method and preparation of test pieces>
Using an applicator, steel plates (JIS G 3141, trade name: SPCC-SB, treatment method: PF-1077, manufactured by Paltec Co., Ltd.) degreased with the methyl ethyl ketone degreased the prepared two-component paint composition so as to give an arbitrary film thickness It applied. Thereafter, heat treatment was performed in a dryer at a temperature of 60 ° C. for 1 hour, followed by aging for 7 days under an environment of a temperature of 23 ° C. and a relative humidity of 50% to obtain coating films S-1 to S-11.

<Weatherability>
The coating film produced from the paint obtained by the composition shown in Table 4 was subjected to an accelerated weathering test under the following conditions.
・ Test device: QUV (made 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.)]
・ Testing time: 864 hours <Evaluation criteria>
According to JIS Z8741, the gloss at 60 ° was measured with a gloss meter (product name: Micro-Gloss, manufactured by BYK) to calculate the gloss retention. The gloss retention was determined by the following equation.
Gloss retention (%) = 100 x gloss after weathering ÷ initial gloss (formula)
・ 50% or more: (Evaluation) A
-Less than 49%: (Evaluation) B.

<Permeability>
An aqueous acrylic polyol (product name: Burnock WE-303, manufactured by DIC Corporation) is applied as a primer to a PP plate using an applicator, and after predrying for 40 minutes at ordinary temperature, in a dryer at 60 ° C. Heat treatment was performed for 20 minutes. Furthermore, the two-component coating composition prepared in Table 3 was applied from above the primer using an applicator, pre-dried at ambient temperature for 15 minutes, and then heat-treated in a dryer at 90 ° C. for 30 minutes. Thereafter, the coated film was peeled off from the PP plate, and the coated surface on the primer side was measured by IR.
<Evaluation criteria>
The absorbance of the peak of wave number 2270 was measured based on the peak absorbance of wave number 700 of the measured IR spectrum, and the absorbance ratio was calculated by the following equation.
(Absorbance of wave number 2270 peak / Absorbance of wave number 700 peak) × 1000 (formula)
・ 1.5 or more: A
-1.0 or more and less than 1.5: B
-Less than 1.0: C.

Preparation of metallic base paint for evaluation of adhesion and flip-flop properties
Rheology control agent (Product name: BYK-425, BYK company) 0.5 g and 2 antifoam agent (Product name: BYK-012) to 25.0 g of aqueous acrylic polyol (Product name: Burnock WE-303, manufactured by DIC) Add 0.5 g of BYK, 1.0 g of wetting dispersant (product name: DISPERBYK-192, manufactured by BYK), and add 2.0 g of aluminum paste (product name: Al paste WXM 5660, manufactured by Toyo Aluminum Co., Ltd.) The viscosity was adjusted by blending and further adding 15.0 g of methanol.

<Adhesiveness / flip-flop property>
The prepared metallic base paint is applied to a steel plate degreased with methyl ethyl ketone (JIS G3141, trade name: SPCC-SB, treatment method: PF-1077, Paltec Co., Ltd.) by spraying so that the film thickness after drying becomes about 30 μm. did. Thereafter, it was aged for 30 minutes under an environment of a temperature of 23 ° C. and a relative humidity of 50%, and was subjected to heat treatment under a condition of 60 ° C. for 30 minutes. Furthermore, the two-component paint composition prepared in Table 3 is applied from above the steel plate coated with metallic base using an applicator, pre-dried for 10 minutes at normal temperature, and heat-treated for 30 minutes in a dryer at 90 ° C. Then, heat treatment was performed at 80 ° C. for 10 hours to obtain a coating film.

<Evaluation criteria of adhesion>
The adhesion test by the cross cut method was implemented according to JISK5600-5-6 of the obtained coating film.
・ Class 0-1: A
-Classification 2-5: B.

<Flip-flop evaluation criteria>
Measure the five-angle color (15 ° / 25 ° / 45 ° / 75 ° / 110 °) with a colorimeter for metallic colors (Product name: BYK-maci 23 mm, BYK company) for the obtained coating film And the flip-flop value was calculated. The flip flop value (FF value) was determined by the following equation.

FF value ^{= 2.69 × (L * 15 °} -L * 110 °) 1.11 / (L * 45 °) 0.86 ( expression)
・ 8.5 or more: A
-Less than 8.5: B

Claims (6)

A polyisocyanate composition comprising an allophanate-modified polyisocyanate obtained from hexamethylene diisocyanate and a monoalcohol, wherein the average degree of polymerization of the allophanate-modified polyisocyanate is 1.5 or less. object. The carbon number of monoalcohol is 1-3, The polyisocyanate composition of Claim 1 characterized by the above-mentioned. The polyisocyanate composition according to claim 1 or 2, comprising a polyisocyanurate. The polyisocyanate composition according to any one of claims 1 to 3, wherein the number of moles of allophanate group / the total number of moles of isocyanurate group and uretdione group = 100/0 to 10/90. Composition. The polyisocyanate composition according to any one of claims 1 to 4, wherein the concentration of uretdione group in the polyisocyanate composition is 5 mol% or less. A two-part paint composition comprising the polyisocyanate composition according to any one of claims 1 to 5 and a polyol.