JP2011105886A - Polyisocyanate composition and two-liquid type polyurethane composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyisocyanate composition which imparts both of good curability and spreadability, that are difficult to be made compatible, to a coating film, and to provide a two-liquid type polyurethane composition which is composed of a curing agent containing the polyisocyanate composition and a main agent containing a polyol, and which forms a coating film having good drying property and scratch resistance. <P>SOLUTION: The polyisocyanate composition is obtained from (A) at least one of diisocyanate selected from aliphatic diisocyanates and alicyclic diisocyanates and (B) a polyester-based polyol derived from a divalent or trivalent alcohol and ε-caprolactone and having a number-average molecular weight of 250-2,000, and substantially contains no isocyanurate group and contains an allophanate group. Further, the two-liquid type polyurethane composition is composed of a curing agent formed from the polyisocyanate composition and a main agent containing a polyol having a hydroxyl value of 5-200 mgKOH/g. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention comprises a polyisocyanate composition obtained from an aliphatic or alicyclic diisocyanate and a polyester polyol, a curing agent containing the polyisocyanate composition, and a main agent containing a polyol, and has excellent extensibility, And a two-component polyurethane composition from which a coating film having drying properties can be obtained.

A coating composition using a polyisocyanate composition is widely used as a coating material for buildings, automobiles, information appliances and the like because of its excellent appearance, weather resistance, and durability. In particular, in applications where high quality appearance and excellent weather resistance and durability are required, such as top coat applications for automobiles and information appliances, a dense cross-linked coating film can be formed and the finished appearance is good. Liquid polyurethane paints are highly appreciated.
For automotive and information appliance applications, in addition to high-quality appearance and excellent weather resistance and durability, a paint composition with even higher hardness while having good extensibility and scratch resistance is desired. ing. In addition, in order to improve work efficiency, a coating film having a quick drying property is also desired. Conventionally, when preparing such a coating composition, a polyol such as an acrylic polyol or a polyester polyol having a relatively high molecular weight is used as a main agent, and a hexamethylene diisocyanate described in Patent Document 1 is used as a curing agent. (Hereinafter referred to as “HDI”), a polyisocyanate composition having a higher number of functional groups by using isocyanurate using diisocyanate and polyhydric alcohol as raw materials, and HDI and isophorone diisocyanate (hereinafter referred to as “Patent Document 2”). , IPDI) and a polyisocyanate composition obtained by using isocyanurate using polyhydric alcohol as raw materials, and a method of imparting high hardness to the coating film has been used. However, since the isocyanuration reaction is a polymerization reaction, if the degree of polymerization is increased in order to increase the functional group, a large number of high molecular weight products are produced, resulting in a very high viscosity, which adversely affects on-site workability. In addition, since the isocyanurate body hardens the coating film, the flexibility is lowered, and the coating film may break due to failure to follow the expansion and contraction of the coating film due to temperature change.

As another method for producing a highly functional polyisocyanate composition, there is a method in which a diisocyanate such as HDI and an alcohol are used as raw materials to form allophanate. The allophanatization reaction is a method in which an isocyanate group is added to a urethane group. The urethane group, which is the raw material of the allophanate reaction, gradually decreases due to the reaction, so the reaction naturally converges, and is like an isocyanurate reaction. Therefore, a relatively low viscosity polyisocyanate composition can be obtained. Patent Documents 3, 4, and 5 are documents that describe a method for producing an isocyanate composition using an allophanatization reaction. In these documents, aliphatic and cycloaliphatic alcohols are listed as examples of usable raw material alcohols, but nothing is described about the influence of alcohol species on the drying and extensibility of the coating film. Absent.
There is Patent Document 6 as a document that describes a method for increasing the drying property. In this document, a polyol having 4 to 10 functional groups introduced into polyisocyanate is used to improve curability, but there is no description of extensibility.
Patent Document 7 is a document describing a method for imparting extensibility. In this document, a method of introducing an elastic component into polyisocyanate is used, but there is no description about the drying property of the coating film.

JP-A-6-312969 International Publication No. 2005/082966 Pamphlet Japanese Patent Laid-Open No. 8-188565 JP-A-7-304724 International Publication No. 2002/32979 Pamphlet Japanese Patent No. 3497610 Japanese Patent Publication No. 64-10023

  In view of the above-described present situation, the present invention provides a polyisocyanate composition having a specific structure and capable of imparting to a coating film properties that make it difficult to achieve both excellent curability and extensibility, and a polyisocyanate composition thereof. An object of the present invention is to provide a two-part polyurethane composition comprising a curing agent and a main ingredient containing a polyol, excellent in weather resistance and durability, and having excellent scratch resistance and drying properties.

As a result of intensive studies, the present inventors have found that a polyisocyanate composition having an allophanate group using a polyester-based polyol having a number average molecular weight of 250 to 2000 derived from a dihydric alcohol and ε-caprolactone as a raw material. And the use of a curing agent containing the polyisocyanate composition and a main agent containing a polyol, the inventors have found that the above object can be achieved, and based on this, the present invention has been completed.
That is, the present invention is as follows.
1) (A) at least one diisocyanate selected from aliphatic diisocyanate and alicyclic diisocyanate; and (B) a polyester system having a number average molecular weight of 250 to 2000 derived from a divalent alcohol and ε-caprolactone. A polyisocyanate composition obtained from a polyol and substantially free of isocyanurate groups and containing allophanate groups.

2) (a) a main agent containing a polyol having a hydroxyl value of 5 to 200 mg KOH / g;
(B) (A) at least one diisocyanate selected from aliphatic diisocyanate and alicyclic diisocyanate, and (B) a polyester having a number average molecular weight of 250 to 2000 derived from a divalent alcohol and ε-caprolactone. A two-component polyurethane composition comprising a curing agent obtained from a system polyol and containing a polyisocyanate composition substantially free of isocyanurate groups and containing allophanate groups.
3) A coating composition for metal or plastic, comprising the two-component polyurethane composition described in 2) above.
4) A paint comprising the two-component polyurethane composition as described in 2) above, which is used for top clear of an automobile body, an automobile metal part, an automobile plastic part, an information household appliance metal part, or an information household appliance plastic part. Composition.

  The polyisocyanate composition of the present invention can impart to the coating film properties that make it difficult to achieve both excellent curability and extensibility, and also from a two-component polyurethane composition using the polyisocyanate composition as a curing agent. The resulting coating film has the characteristics of excellent weather resistance and durability, and good scratch resistance and drying properties.

The present invention will be specifically described below.
The polyisocyanate composition of the present invention comprises (A) at least one diisocyanate selected from aliphatic diisocyanates and alicyclic diisocyanates, and (B) a number average molecular weight derived from a divalent alcohol and ε-caprolactone. Is obtained from a polyester-based polyol having a molecular weight of 250 to 2000, and is substantially free of isocyanurate groups and contains allophanate groups.

First, at least one diisocyanate selected from (A) aliphatic diisocyanate and alicyclic diisocyanate will be described.
An aliphatic diisocyanate is a compound having a saturated aliphatic group in the molecule. On the other hand, alicyclic diisocyanate is a compound having a cyclic aliphatic group in the molecule. Use of an aliphatic diisocyanate is more preferable because the resulting polyisocyanate composition has a low viscosity. Examples of the aliphatic diisocyanate include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane (hexamethylene diisocyanate, hereinafter referred to as HDI), 1,6-diisocyanato-2, Examples include 2,4-trimethylhexane, methyl 2,6-diisocyanatohexanoate (lysine diisocyanate), and the like. Examples of the alicyclic diisocyanate include 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane (isophorone diisocyanate, hereinafter referred to as IPDI), 1,3-bis (isocyanatomethyl) cyclohexane (hydrogenated xylylene). Range isocyanate), bis (4-isocyanatocyclohexyl) methane (hydrogenated diphenylmethane diisocyanate), 1,4-diisocyanatocyclohexane and the like. Among these, HDI, IPDI, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate are preferable because they are easily available industrially. Among them, HDI is most preferable because it has excellent weather resistance and flexibility of the coating film. Hereinafter, aliphatic diisocyanate and alicyclic diisocyanate are collectively referred to as diisocyanate.

  For the polyisocyanate composition, (B) a polyester polyol having a number average molecular weight of 250 to 2000 derived from a divalent alcohol and ε-caprolactone is used as a raw material. The upper limit of the number average molecular weight of the polyester polyol is preferably 1800, more preferably 1400, and still more preferably 1000. If the number average molecular weight is 250 to 2000, the extensibility of the coating film is sufficient and the viscosity of the coating liquid does not become too high. The polyester polyol may be used alone or in combination of two or more. The polyester polyol used in the present invention is derived from a divalent alcohol and ε-caprolactone. Examples of the divalent to trivalent alcohol include 1,2-propylene glycol, 1,3-butylene glycol, neopentyl glycol, hydroxypivalate ester of neopentyl glycol, 2-methyl-1,3-propanediol, 2, 3,5-trimethylpentanediol, ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butylenediol, 1,5-pentanediol, 1,6-hexanediol, trimethylolpropane, glycerin, 1, 1,7-trimethylol heptane, 1,2,7-trimethylol heptane and the like can be mentioned. These may be used alone or in combination of two or more.

The viscosity of the polyisocyanate composition is 500 to 15000 mPa.s in terms of the amount of organic solvent and the number of functional groups. s is preferred. 500 mPa.s. s or more, the number of functional groups can be sufficiently increased, and 15000 mPa.s. If it is s or less, the amount of organic solvent can be reduced. More preferably, 600-12000 mPa.s. s, and more preferably 700 to 10000 mPa.s. s. The viscosity was measured at 25 ° C. using an E-type viscometer (Tokimec Co., Ltd.).
The number average functional group number (hereinafter, fn) of the polyisocyanate composition is preferably 3.5 to 7.0 in terms of curability and viscosity. If fn is 3.5 or more, sufficient curability is obtained, and if it is 7.0 or less, the viscosity does not become too high. Preferably, it is 3.6-6.9, More preferably, it is 3.7-6.8.
The fn of the polyisocyanate composition was determined from the following formula. (Fn of polyisocyanate composition) = (number average molecular weight) × NCO% / 4200.

  The number average molecular weight is gel filtration chromatography (hereinafter referred to as GPC. Equipment used: HLC-8120 (manufactured by Tosoh Corporation), column used: TSK GEL SuperH1000, TSK GEL SuperH2000, TSK GEL SuperH3000 (all manufactured by Tosoh Corporation), Sample concentration: 5 wt / vol%, carrier: THF, detection method: differential refractometer, flow rate 0.6 ml / min, column temperature 30 ° C.). GPC calibration curves are polystyrene (molecular weight 50000-2050) (PSS-06 (Mw 50000), BK 13007 (Mp = 20000, Mw / Mn = 1.03), PSS-08 (Mw = 9000), PSS, manufactured by GL Sciences Inc.). -09 (Mw = 4000), 5040-35125 (Mp = 2050, Mw / Mn = 1.05) and 3 of isocyanurate bodies of HDI polyisocyanate composition (Duranate TPA-100, manufactured by Asahi Kasei Chemicals Corporation) A monomer to a 7-mer (isocyanurate trimer molecular weight = 504, isocyanurate pentamer molecular weight = 840, isocyanurate heptamer molecular weight = 1176) and HDI (molecular weight = 168) were prepared as standards. Invented polyisocyanate composition, polyol composition, etc. Molecular weight, all calculated by the above method.

The NCO% of the polyisocyanate composition is preferably 3.0% to 25.0% from the viewpoint of performance when formed into a coating film at a solid content of 100%. If it is 3.0% or more, the performance when formed into a coating film is good, and if it is 25.0% or less, the crosslinking density does not become too high, and a coating film that is hard to break is formed. More preferably, it is 3.2% to 24.0%, and still more preferably 3.4% to 23.0%. NCO% was determined by back titration with 1N hydrochloric acid after neutralizing the isocyanate group with excess 2N amine.
The polyisocyanate composition is substantially free of isocyanurate groups and contains allophanate groups. “Substantially” means that the molar ratio of allophanate group to isocyanurate group is 91/9 to 100/0. Preferably it is 93 / 7-100 / 0, More preferably, it is 95 / 5-100 / 0, More preferably, it is 97 / 3-100 / 0. It is surprising that if the molar ratio of allophanate group to isocyanurate group is in the range of 91/9 to 100/0, the viscosity of the polyisocyanate composition does not increase and a coating film with excellent extensibility can be formed. is there.

The molar ratio of allophanate groups to isocyanurate groups can be determined by 1H-NMR. An example of a method for measuring a polyisocyanate composition using HDI and an isocyanate prepolymer obtained therefrom as a raw material by 1H-NMR is shown below.
Example of 1H-NMR Measurement Method: A polyisocyanate composition is dissolved in deuterium chloroform at a concentration of 10% by mass (0.03% by mass tetramethylsilane is added to the polyisocyanate composition). As a chemical shift standard, a hydrogen signal of tetramethylsilane was set to 0 ppm. Measured by 1H-NMR, adjacent to a signal of a hydrogen atom bonded to nitrogen of an allophanate group near 8.5 ppm (1 mol of hydrogen atom per 1 mol of allophanate group) and an isocyanurate group near 3.85 ppm The signal area ratio of the hydrogen atom of the methylene group (6 mol of hydrogen atom relative to 1 mol of isocyanurate group) is measured.
Allophanate group / isocyanurate group = (signal area around 8.5 ppm) / (signal area around 3.85 ppm / 6)

  Moreover, since the uretdione body is easily dissociated by heat or the like to generate HDI, it is preferable to reduce the content. The content of the uretdione body is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 5% by mass or less with respect to the polyisocyanate composition. The content of the uretdione compound can be determined by measuring the ratio of the area of the peak having a molecular weight of about 336 in gel filtration chromatography (hereinafter referred to as GPC) with a differential refractometer. When there is a peak that hinders measurement near the peak of about 336, the peak height of the uretdione group of about 1770 cm −1 and the peak of the allophanate group of about 1720 cm −1 are measured using FT-IR. The ratio can also be obtained by a method of quantifying using an internal standard.

Since biuret bodies and other diisocyanate polymers may adversely affect the weather resistance and the like of the coating film, it is not preferable that the content is increased. The amount of biuret and other diisocyanate polymer contained in the polyisocyanate composition of the present invention is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 3% by mass or less. It is.
The urethane body may improve the adhesion to the substrate, but if it is too large, the number average functional group number may decrease and the crosslinkability may decrease. In the polyisocyanate composition used in the present invention, the range of the amount of urethane contained is represented by mol% of urethane groups with respect to the total number of moles of allophanate groups and isocyanurate groups, preferably less than 10 mol%, more It is preferably 8 mol% or less, and more preferably 6 mol% or less. The mol% of the urethane group can be determined using 1H-NMR. By the above method, the total number of moles of allophanate group and isocyanurate group was measured, and further, hydrogen atoms bonded to nitrogen of urethane group in the vicinity of 4 to 5 ppm (1 mol hydrogen atom per 1 mol urethane group). By measuring the number of moles of the urethane group from the area of the signal, the mole% of the urethane group can be measured.

Hereinafter, the manufacturing method of a polyisocyanate composition is demonstrated. The polyisocyanate composition can be obtained by an allophanatization reaction of a compound formed by urethanation reaction of diisocyanate and polyester polyol.
The molar ratio of the isocyanate group to the hydroxyl group of the diisocyanate and the polyester polyol is 6/1 to 100/1, preferably 8/1 to 80/1, more preferably 10/1 to 60/1. If the isocyanate group is excessive to 6/1 or more, a low-viscosity polyisocyanate composition can be produced. If a hydroxyl group is present at 100/1 or more, production efficiency can be maintained.

As the order of urethanization reaction and allophanate reaction, considering the ease of production, allophanate reaction is performed together with urethanization reaction of diisocyanate and polyester polyol, or after urethanation reaction if necessary A reaction method is more preferred.
The allophanatization reaction can be performed using a known allophanate catalyst. Examples of preferred catalysts are compounds containing lead, compounds containing zinc, compounds containing tin, compounds containing zirconium, compounds containing bismuth, and compounds containing lithium. One or two or more of these compounds can be used.

Among these catalysts, a compound containing zinc, a compound containing lead, a compound containing tin, a compound containing zirconium, and a compound containing zirconium are more preferable. Examples of the compound containing zirconium include zirconyl naphthenate and zirconyl 2-ethylhexanoate. These are particularly preferable because they are relatively inexpensive, easily available industrially, have high selectivity for the allophanatization reaction, and have high safety.
In the present invention, the method for adding the allophanatization catalyst is not limited. For example, it may be added before the production of a compound containing a urethane group, that is, prior to the reaction between the diisocyanate and the alcohol, or may be added during the reaction between the diisocyanate and the alcohol, or after the production of the urethane group-containing compound. May be.
In addition, as a method of addition, a required amount of the allophanatization catalyst may be added all at once, or may be added in several divided portions. Or the method of adding continuously at a fixed addition rate is also employable.

The allophanatization reaction is generally performed at a temperature of 20 to 200 ° C. Preferably, it is 30-180 degreeC, More preferably, it is 60-160 degreeC. If it is 20 degreeC or more, an allophanatization reaction can be advanced at a suitable reaction rate, without raising a side reaction. If it is 200 degrees C or less, it will become possible not to raise | generate a side reaction and coloring.
In the allophanatization reaction when producing the polyisocyanate composition, it is preferable that the conversion rate from the urethane group to the allophanate group is as high as possible. The conversion rate is preferably 91% or more, more preferably 92% or more. By converting from a urethane group to an allophanate group, it is possible to increase the fn of the isocyanate group while maintaining a relatively low viscosity.
The urethanization reaction and allophanatization reaction proceed in the absence of solvent, but have reactivity with isocyanate groups such as butyl acetate, methyl ethyl ketone, toluene, xylene, hydrocarbon solvents, aromatic solvents as necessary. Organic solvents that are not used can be used as the solvent.
The course of the reaction can be followed by measuring the NCO% of the reaction mixture or by measuring the refractive index.

  The allophanatization reaction can be stopped by cooling to room temperature or adding a reaction terminator, but when using an allophanate catalyst, it is more stable to add a reaction terminator to stop the stability of the polyisocyanate composition. Is preferable. The amount of the reaction terminator added is 0.2 to 100 times the molar amount, preferably 0.5 to 50 times the molar amount, more preferably 1.0 to 20 times the molar amount relative to the allophanatization catalyst. It is. If it is 0.2 times or more, the catalyst can be completely deactivated. In the case of 100 times or less, it becomes possible to obtain a polyisocyanate composition having no turbidity. Any reaction terminator may be used as long as it deactivates the allophanatization catalyst. Examples of reaction terminators include phosphoric acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid and other phosphoric acid compounds, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric monoalkyl or dialkyl esters, monochloroacetic acid, etc. Examples include halogenated acetic acid, benzoyl chloride, sulfonic acid ester, sulfuric acid, sulfuric acid ester, ion exchange resin, chelating agent and the like. From an industrial viewpoint, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, phosphoric acid monoalkyl ester, and phosphoric acid dialkyl ester are preferable because they hardly 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, 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 substantially not containing water are more preferable as a terminator. When used in a state that does not contain water, the reaction product of the terminator and the catalyst is likely to precipitate, so that the reaction product of the terminator and the catalyst is less likely to remain in the polyisocyanate composition. . Furthermore, when used in a state not containing water, the reaction product of water and isocyanate does not mix in the polyisocyanate composition, so there is no increase in viscosity of the polyisocyanate composition and the dilutability with respect to the organic solvent is reduced. There is also an effect that there is no. In the present invention, “substantially not containing water” means that water may be contained as long as the above-described effects are exhibited. Less than 0.0 mass%, preferably less than 2.0 mass%, more preferably less than 0.50 mass%.

As another preferable stopping method when using an allophanate catalyst, there is a method of stopping the reaction by adsorbing the catalyst with an adsorbent. It is also a preferable method to stop by combining the adsorbent and the above reaction terminator. Examples of the adsorbent include silica gel, activated carbon, and activated alumina. The amount of adsorbent added is preferably 0.05 to 10% by mass based on the diisocyanate used in the reaction.
After completion of the reaction, the polyisocyanate composition is preferably separated from unreacted diisocyanate and solvent. Examples of a method for separating unreacted diisocyanate and solvent include a thin film distillation method and a solvent extraction method.
In the reaction in the present invention, a urethanization reaction and an allophanatization reaction can be performed in one reactor. Moreover, two reactors can be connected, and the urethanization reaction step and the allophanatization reaction step can be carried out separately. Alternatively, it can be carried out continuously by arranging several reactors side by side.

Next, the main agent of the present invention will be described in detail.
The main agent of the present invention contains a polyol having a hydroxyl value of 5 to 200 mgKOH / g.
The hydroxyl value of the polyol is 5 to 200 mg KOH / g. The lower limit of the hydroxyl value is preferably 10 mgKOH / g, more preferably 15 mgKOH / g, and still more preferably 20 mgKOH / g. The upper limit is preferably 160 mgKOH / g, more preferably 120 mgKOH / g, and still more preferably 80 mgKOH / g. When the hydroxyl value is 5 to 200 mgKOH / g, a two-component polyurethane composition capable of obtaining a flexible and tough coating film can be obtained.

  Examples of the polyol used as the main agent include acrylic polyols, polyester polyols, polyether polyols, polyolefin polyols, silicon-containing polyols, fluorine-containing polyols, polycarbonate polyols, epoxy resins, and alkyd polyols. Or a mixture thereof. In addition, as the polyol, an urethane modified acrylic polyol, a urethane modified polyester polyol or a urethane obtained by modifying an acrylic polyol, a polyester polyol or a polyether polyol with an aliphatic diisocyanate, an alicyclic diisocyanate or a polyisocyanate composition obtained therefrom. Modified polyether polyols can also be used.

Polyols can be produced by a known technique. Hereinafter, typical methods for producing acrylic polyols, polyester polyols and polyether polyols will be described.
The acrylic polyol can be produced, for example, by copolymerizing a polymerizable monomer having one or more active hydrogens in one molecule and 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 and methacrylic acid-2- Methacrylic acid esters having active hydrogen such as hydroxypropyl, methacrylic acid-2-hydroxybutyl, methacrylic acid-3-hydroxypropyl, methacrylic acid-4-hydroxybutyl, or triol monoacrylate such as glycerin and trimethylolpropane (Meth) acrylic acid esters having polyvalent active hydrogen such as ester or methacrylic acid monoester, polyether polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol and the above active hydrogen Monoethers with (meth) acrylic acid esters, adducts of glycidyl (meth) acrylates with monobasic acids such as acetic acid, propionic acid, p-tert-butylbenzoic acid, or the above active hydrogens (meta ) As an essential component, a single or mixture selected from the group of adducts obtained by ring-opening polymerization of lactones such as ε-caprolactam and γ-valerolactone to active hydrogen of acrylic esters Acrylic esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, -n-butyl acrylate, 2-ethylhexyl acrylate, or methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, methacrylic acid -n- Butyl, isobutyl methacrylate, methacrylic acid-n-he Silyl, cyclohexyl methacrylate, lauryl methacrylate, methacrylic acid esters such as glycidyl methacrylate, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide, N-methylol acrylamide, diacetone acrylamide, etc. Unsaturated amides or vinyl monomers having hydrolyzable silyl groups such as vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ- (meth) acrylopropyltrimethoxysilane, styrene, vinyltoluene, vinyl acetate, acrylonitrile A single or a mixture selected from the group of other polymerizable monomers such as dibutyl fumarate can be copolymerized by a conventional method. For example, the monomer component can be obtained by solution polymerization in the presence of a known radical polymerization initiator such as a peroxide or an azo compound.

  Examples of the method for producing polyester polyol include succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, and 1,4-cyclohexanedicarboxylic acid alone or as a mixture. , Ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, 1,2-, 1,3- and 1,4-cyclohexanediol, trimethylol It can be obtained by performing a known condensation reaction with a single or mixture of polyhydric alcohols such as propane, glycerin, pentaerythritol, 2-methylolpropanediol and ethoxylated trimethylolpropane. For example, it can be done by combining the above ingredients and heating at about 160-220 ° C. Furthermore, polycaprolactones obtained by ring-opening polymerization of lactones such as ε-caprolactone using a polyhydric alcohol can also be used as the polyester polyol.

  As a manufacturing method of polyether polyol, polyhydric alcohol, polyhydric phenol, polyamine, alkanolamine, etc., specifically, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4- Dihydric alcohols such as butanediol, 1,6-hexanediol, and bisphenol A, trihydric alcohols such as glycerin and trimethylolpropane, and diamines such as ethylenediamine, alone or in a mixture, for example, hydroxides such as lithium, sodium, and potassium , Strongly basic catalysts such as alcoholates and alkylamines, metalloporphyrins, complex metal cyanide complexes, complexes of metals with tridentate or higher chelating agents, complex metal complexes such as zinc hexacyanocobaltate complexes Use, ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, obtained by adding, alone or mixtures of alkylene oxides such as styrene oxide.

Hereinafter, the two-component polyurethane composition of the present invention will be described.
The two-component polyurethane composition comprises (a) a main agent containing a polyol having a hydroxyl value of 5 to 200 mg KOH / g, and (b) at least one diisocyanate selected from (A) an aliphatic diisocyanate and an alicyclic diisocyanate. And (B) a poly-polyol obtained from a polyester-based polyol having a number average molecular weight of 250-2000 derived from a divalent alcohol and ε-caprolactone, substantially free of isocyanurate groups and containing allophanate groups. A curing agent containing an isocyanate composition.

In the two-component polyurethane composition, the mixing ratio of (A) the main agent and (B) the curing agent is a molar ratio of isocyanate group / hydroxyl group and is preferably in the range of 0.1 to 5.0. The lower limit of the molar ratio is more preferably 0.3, even more preferably 0.4, and most preferably 0.5. The upper limit of the molar ratio is more preferably 4.0, even more preferably 3.0, and most preferably 2.0. In the range of 0.1 to 5.0, a tough coating film can be formed.
The two-component polyurethane composition has a coloring pigment, a dye, a silane coupling agent for improving the adhesion of the coating film, an ultraviolet absorber, and a curing, as long as the effects of the present invention are not impaired, depending on the purpose and application. Various additives used in the technical field such as accelerators, light stabilizers, matting agents, coating surface hydrophilizing agents, catalysts, drying improvers, leveling agents, antioxidants, plasticizers, surfactants, etc. Can also be used in combination.

Examples of coloring pigments and dyes include inorganic pigments such as carbon black and titanium oxide having good weather resistance, organic pigments such as phthalocyanine blue, phthalocyanine green, quinacridone red, indanthrene orange, and isoindolinone yellow, and dyes. .
Examples of silane coupling agents include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, ureidopropyltriethoxysilane, and vinyltriethoxysilane. , Vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3 -Mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane and the like.

Examples of the ultraviolet absorber include benzophenone-based, benzotriazole-based, triazine-based, and cyanoacrylate-based ultraviolet absorbers.
Examples of the light stabilizer include hindered amine light stabilizers and the like. Ciba Specialty Chemicals), Sanol LS765 (trade name, manufactured by Sankyo Lifetech Co., Ltd.) and the like.
Examples of the matting agent include ultrafine powdered synthetic silica. When the matting agent is used, an elegant semi-gloss and matte finish coating film can be formed.
As the coating surface hydrophilic agent, a silicate compound is preferable. By containing a silicate compound, when a coating film is produced using a two-component polyurethane composition, the coating film surface is rendered hydrophilic and rain-stain stain resistance is exhibited. Since the silicate compound reacts with the hydroxyl group, it is preferable to add it to the (b) curing agent when mixing in advance. Alternatively, (b) the main agent and (b) the curing agent may be mixed at the same time.

Examples of the silicate compound include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetraisobutoxysilane, tetra-tert-butoxysilane, dimethoxydiethoxysilane, Examples thereof include tetraphenoxysilane and condensates thereof. Among these, the condensate of tetramethoxysilane and the condensate of tetraethoxysilane are preferable because the surface of the coating tends to be hydrophilic when a coating is prepared.
Examples of curing accelerator catalysts include dialkyltin dicarboxylates such as dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, tin oxide compounds such as dibutyltin oxide, tin 2-ethylhexanoate, zinc 2-ethylhexanoate , Metal carboxylates such as cobalt salts, triethylamine, pyridine, methylpyridine, benzyldimethylamine, N, N-dimethylcyclohexylamine, N-methylpiperidine, pentamethyldiethylenetriamine, N, N′-endoethylenepiperazine, and N, And tertiary amines such as N′-dimethylpiperazine.
Examples of the drying improver include CAB (cellulose acetate butrate), NC (nitrocellulose) and the like.

The two-pack type polyurethane composition is a two-pack type paint in which (a) the main agent and (b) the curing agent are mixed and used at the coating site, and additives can be mixed as necessary.
The mixing order is not particularly limited, and examples of use are given below.
・ Use method that mixes hardening agent in the painting site with main ingredient that mixed additive beforehand,
・ Use method that mixes main agent and hardening agent at the painting site, and then adds additive,
-The usage method which mixes the hardening | curing agent which mixed the additive beforehand with the main agent which mixed the additive previously at the painting site.
As a method of coating using the two-component polyurethane composition, any method such as spray coating, air spray coating, brush coating, dipping method, roll coater, flow coater and the like can be applied.

The coating composition using the two-component polyurethane composition of the present invention uses a highly functional polyisocyanate composition having a specific structure and a main component polyol, and the obtained coating film is good. The coating composition using the two-component polyurethane composition of the present invention can be used for automotive applications, information appliance applications, and information equipment applications such as personal computers and mobile phones.

Examples of the method for synthesizing the polyisocyanate composition of the present invention and the two-component polyurethane composition of the present invention are described below.
The mole fraction of allophanate groups was determined by using 1H-NMR (FT-NMR DPX-400 manufactured by Bruker), hydrogen signal on the nitrogen atom of allophanate groups near 8.5 ppm, and isocyanurate near 3.8 ppm. It was determined from the area of the hydrogen signal of the methylene group next to the nitrogen atom of the isocyanurate ring of the group.
NCO% was determined by back titration with 1N hydrochloric acid after neutralizing the isocyanate group with excess 2N amine.
The viscosity was measured at 25 ° C. using an E-type viscometer (manufactured by Tokimec Co., Ltd.).
A standard rotor (1 ° 34 ′ × R24) was used. The number of revolutions is as follows.
100r. p. m. (If less than 128 mPa.s)
50r. p. m. (In the case of 128 mPa.s to 256 mPa.s)
20r. p. m. (In the case of 256 mPa.s to 640 mPa.s)
10r. p. m. (In the case of 640 mPa.s to 1280 mPa.s)
5r. p. m. (In the case of 1280 mPa.s to 2560 mPa.s)
2.5r. p. m. (In the case of 2560 mPa.s to 5120 mPa.s)
1r. p. m. (In the case of 5120 mPa.s to 10240 mPa.s)
0.5r. p. m. (In the case of 10240 mPa.s to 20480 mPa.s)

The gel fraction was determined from the mass of a coating film obtained by immersing about 0.1 g of a coating film in acetone at 20 ° C. for 24 hours, taking out the coating film, and drying at 80 ° C. for 1 hour.
The elongation of the coating film was measured using a tensile tester (manufactured by Shimadzu Corp., AGS 500G) under the conditions of a temperature of 23 ° C. and a humidity of 50% RH at a pulling speed of 20 mm / min and a grip interval of 20 mm.
The scratch resistance test was performed by the following method using a rubbing tester (manufactured by Taihei Rika Kogyo Co., Ltd.). The 20 ° gloss of the coated surface was measured in advance. Cleanser (trade name Marzen Cleanser, manufactured by Marzen Cleanser Co., Ltd.) and water were mixed at 3: 2 to obtain an abrasive. About 1 g of the abrasive was adhered to the sponge of the rubbing tester, a 200 g load was applied, and the coating film of the test plate was rubbed back and forth 20 times. Thereafter, the coated surface was washed with running water, and after natural drying, the 20 ° gloss of the coated surface was measured. The 20 ° gloss retention is calculated according to the following formula, and the value is used as an evaluation value for scratch resistance.
20 ° gloss retention = (20 ° gloss after test / 20 ° gloss before test) × 100

[Synthesis Example 1]
The inside of a four-necked flask equipped with a stirrer, a thermometer, and a cooling tube is purged with nitrogen, and a polyester polyol “Placcel 305” derived from HDI 1200 g, trihydric alcohol and ε-caprolactone (trade name of Daicel Chemical Industries) Number average molecular weight 500) 130 g was charged, and urethanization reaction was performed at 130 ° C. for 1 hour with stirring. Thereafter, 0.42 g of a 20% octanol solution of zirconyl 2-ethylhexanoate was added as an allophanatization catalyst. When the increase in the refractive index of the reaction solution reached 0.0052, a 10% solid pyrophosphoric acid 2-ethyl-1-hexanol solution (trade name “phosphoric acid (105%)” manufactured by Taihei Chemical Industry Co., Ltd. 3.9 g of a solution diluted with ethyl-1-hexanol) was added to stop the reaction.
After filtering the reaction solution, unreacted HDI was removed at 160 ° C. (27 Pa) for the first time and 150 ° C. (13 Pa) for the second time using a flow-down type thin-film distillation apparatus.
The resulting polyisocyanate composition was a transparent liquid, yield 300 g, viscosity 8000 mPa.s. s, NCO content 15.0%, fn = 6.0. When NMR was measured, the molar ratio of allophanate group / isocyanurate group was 97/3. Let the obtained polyisocyanate composition be S-1.

[Synthesis Example 2]
In the same apparatus as in Synthesis Example 1, 1000 g of HDI, 170 g of polyester polyol “Placcel 308” (trade name number average molecular weight 800 of Daicel Chemical Co., Ltd.) derived from trihydric alcohol and ε-caprolactone were charged and stirred at 90 ° C. The urethanization reaction was carried out for 1 hour. After raising the temperature to 130 ° C., 0.36 g of a 20% mineral spirit solution of zirconyl 2-ethylhexanoate as an allophanatization catalyst was added. When the increase in the refractive index of the reaction solution reached 0.0043, a 10% solid pyrophosphoric acid 2-ethyl-1-hexanol solution (trade name “phosphoric acid (105%)” manufactured by Taihei Chemical Industry Co., Ltd. -Diluted with ethyl-1-hexanol) was added to stop the reaction.
After filtration of the reaction solution, unreacted HDI was removed in the same manner as in Synthesis Example 1.
The obtained polyisocyanate composition was a transparent liquid, yield 290 g, viscosity 6000 mPa.s. s, NCO content: 13.3%, fn = 5.8. When NMR was measured, the allophanate / isocyanurate molar ratio was 97/3. Let the obtained polyisocyanate composition be S-2.

[Synthesis Example 3]
In the same apparatus as in Synthesis Example 1, 600 g of HDI and 16 g of trimethylolpropane (number average molecular weight 134) were charged, and a urethanization reaction was performed at 90 ° C. for 1 hour with stirring. After raising the temperature to 130 ° C., 0.21 g of a 20% mineral spirit solution of zirconyl 2-ethylhexanoate as an allophanatization catalyst was added. When the increase in the refractive index of the reaction solution reached 0.0050, 0.12 g of 2-ethylhexyl phosphate (manufactured by Johoku Chemical Industry Co., Ltd., trade name “JP-508”) was added to stop the reaction.
After filtration of the reaction solution, unreacted HDI was removed in the same manner as in Synthesis Example 1.
The resulting polyisocyanate composition is a transparent liquid, yield 120 g, viscosity 7200 mPa.s. s, NCO content: 22.8%, fn = 6.0. When NMR was measured, the allophanate / isocyanurate molar ratio was 97/3. Let the obtained polyisocyanate composition be P-1.

[Synthesis Example 4]
In the same apparatus as in Synthesis Example 1, 600 g of HDI, 30 g of polyester polyol “Placcel 303” (trade name: number average molecular weight 300 of Daicel Chemical Co., Ltd.) derived from trihydric alcohol and ε-caprolactone were charged and stirred at 90 ° C. The urethanization reaction was carried out for 1 hour. After the temperature was lowered to 60 ° C., 0.10 g of tetramethylammonium capryate was added as an isocyanurate forming catalyst. When the conversion rate reached 54%, 0.21 g of phosphoric acid was added to stop the reaction.
After filtration of the reaction solution, unreacted HDI was removed in the same manner as in Synthesis Example 1.
The obtained polyisocyanate composition was a transparent liquid, yield 320 g, viscosity 10000 mPa.s. s, NCO content: 19.2%, fn = 5.4. When NMR was measured, the molar ratio of allophanate / isocyanurate was 28/72. Let the obtained polyisocyanate composition be P-2.

[Synthesis Example 5]
In the same apparatus as in Synthesis Example 1, 1000 g of HDI, 200 g of polyester polyol “Placcel 308” (trade name: number average molecular weight 800 of Daicel Chemical Co., Ltd.) derived from trihydric alcohol and ε-caprolactone were charged and stirred at 100 ° C. The urethanization reaction was carried out for 1 hour.
After filtration of the reaction solution, unreacted HDI was removed in the same manner as in Synthesis Example 1.
The obtained polyisocyanate composition was a transparent liquid, yield 320 g, viscosity 6000 mPa.s. s, NCO content: 9.0%, fn = 3.0. When NMR was measured, no allophanate was detected. Let the obtained polyisocyanate composition be P-3.

[Synthesis Example 6]
60 g of polyisocyanate composition S-1 and 440 g of Duranate ^TM TPA-100 (manufactured by Asahi Kasei Chemicals Corporation, isocyanurate type polyisocyanate, NCO content 23.0%) were blended to obtain a polyisocyanate composition.
The obtained polyisocyanate composition is a transparent liquid and has a viscosity of 6500 mPa.s. s, NCO content: 16.0%, fn = 3.7. When NMR was measured, the molar ratio of allophanate / isocyanurate was 85/15. Let the obtained polyisocyanate composition be P-4.

[Examples 1-2, Comparative Examples 1-4]
A two-component polyurethane composition was prepared as follows.
As the main agent, acrylic polyol (trade name “SETALUX1767” from Nuplex, resin concentration 65%, hydroxyl value 150 mg / g resin), and polyisocyanate compositions S-1 to S-2, P-1 as curing agents Using P-4, the molar ratio of isocyanate group / hydroxyl group was adjusted to 1/1. As a solvent, urethane thinner (toluene (manufactured by Wako Pure Chemical Industries, Ltd.): butyl acetate (manufactured by Wako Pure Chemical Industries, Ltd.): ethyl acetate (manufactured by Wako Pure Chemical Industries, Ltd.): xylene (manufactured by Wako Pure Chemical Industries, Ltd.) ): Propylene glycol methyl ether AC (mixed at a weight ratio of 30: 30: 20: 15: 5) was used to adjust the solid content to 50%.

As an index of curability, the gel fraction at the initial curing stage of the coating film was measured. The gel fraction was measured when the film was applied to a polypropylene plate with a bar coder so that the film thickness was about 50 microns and then dried at 23 ° C. for one day. The results are shown in Table 1. In Table 1, 80% or more is indicated by a symbol O, and less than 80% is indicated by a symbol X.
As an indicator of drying property, gauze drying property of the coating film was measured. After applying to a glass plate with a bar coder so that the film thickness was about 50 microns, it was dried at 23 ° C. for 16 hours. Five sheets of Japanese pharmacopoeia gauze were layered on the coating film, and 100 g of weight was placed on it for 60 seconds. Thereafter, the weight and gauze are removed, and the gauze trace remaining on the coating film is observed. The case where there was no trace was indicated by ◯, the case where a trace remained slightly, Δ, and the case where a trace clearly remained was indicated by X.

As an index for the elongation of the coating film, it was applied to a polypropylene plate with a bar coder so that the film thickness was about 50 microns, then cured for 14 days at 23 ° C. and 50% RH, and then pulled using the coating film. A test was conducted. The results are shown in Table 1. In Table 1, the coating film elongation of 50% or more is indicated by ◯, 50-30% is indicated by Δ, and 30% or less is indicated by ×.
A scratch resistance test of the coating film was performed as an index of scratch resistance. A bar coder was applied to a white-coated aluminum plate so as to have a film thickness of about 50 microns, followed by drying at 23 ° C. for 14 days, and then the scratch resistance test was performed. The results are shown in Table 1. In addition, the gloss retention was 80% or more, ○, 80 to 70% was Δ, and less than 70% was ×.

Since the polyisocyanate composition of the present invention has a high number of functional groups and a flexible structure, the coating film can be imparted with properties that are difficult to achieve both excellent curability and extensibility. Therefore, a coating film made of a two-component polyurethane composition in which a curing agent made of the polyisocyanate composition of the present invention and a main ingredient made of polyol are combined is excellent in weather resistance and durability, and further has good drying properties and good properties. It has the characteristic of having excellent scratch resistance.
Therefore, the two-component polyurethane composition of the present invention using the polyisocyanate composition of the present invention as a curing agent should be used as a raw material for paints, inks, adhesives, inks, casting materials, elastomers, foams, and plastic materials. Can do. Among them, it can be used for paints for buildings, paints for heavy anticorrosion, paints for automobiles, paints for information appliances, paints for information devices such as personal computers and mobile phones. In particular, it is suitable for paints for automobiles and paints for information appliances.

Claims (4)

  (A) From at least one diisocyanate selected from aliphatic diisocyanate and alicyclic diisocyanate, and (B) a polyester-based polyol having a number average molecular weight of 250 to 2000 derived from a divalent alcohol and ε-caprolactone. A polyisocyanate composition obtained which is substantially free of isocyanurate groups and contains allophanate groups. (A) a main agent containing a polyol having a hydroxyl value of 5 to 200 mgKOH / g;
(B) (A) at least one diisocyanate selected from aliphatic diisocyanate and alicyclic diisocyanate, and (B) a polyester having a number average molecular weight of 250 to 2000 derived from a divalent alcohol and ε-caprolactone. A curing agent obtained from a system polyol and substantially free of isocyanurate groups and containing a polyisocyanate composition containing allophanate groups,
A two-component polyurethane composition comprising:   A coating composition for metal or plastic, comprising the two-component polyurethane composition according to claim 2.   A coating composition comprising the two-component polyurethane composition according to claim 2 for top clear use of an automobile body, an automobile metal part, an automobile plastic part, an information household appliance metal part, or an information household appliance plastic part. .