JP2000136226A - Polyol mixture having low viscosity and two-pack polyurethane coating material comprising the same mixture and polyisocyanate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyurethane coating material excellent in coating properties without using any solvent and forming a coating film excellent in water resistance and low-viscosity polyol mixture suitable as a raw material for the coating material. SOLUTION: This polyol mixture comprises a diol represented by the formula: OH-(X-O)m-Z-O-(X-O)n-H [X is a 2-4C alkylene; Z is a dimer diol residue; (m) and (n) is an integer the same as or different from each other and 2<=(m+n)<=40] and other polyol and contains the diol of the formula in an amount of >=50 wt.% based on total amount of the whole polyol and has <=2,000 cps viscosity at 25 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyurethane paint which forms a coating film having excellent coatability and excellent water resistance even without a solvent, and a polyol mixture suitable as a raw material of the paint. The polyurethane paint of the present invention has water resistance,
It is excellent in flexibility, substrate followability, cold resistance, appearance, mechanical strength, etc., and can be used in various fields including protective paint for cement outer walls, protective paint for bridges and other buildings. .

[0002]

2. Description of the Related Art In the field of paints in recent years,
From the standpoints of environmental protection, human body safety, and resource saving, water-based paints and powder paints have been widely used in place of solvent-based paints conventionally used widely. However, in the case of a water-based paint, there is a problem that the water resistance of the coating film is inferior due to the combined use of an emulsifier and a dispersant and the hydrophilicity of the polymer. On the other hand, powder coatings generally have low gloss, are limited in the material of the coating from the viewpoint of adhesion, and have the disadvantage that a uniform coating film having a small thickness is difficult to form. As a paint that does not use a solvent or an aqueous medium, a solventless liquid polyurethane paint composed of polypropylene glycol and polyisocyanate is known. This paint is excellent in environmental protection, safety, resource saving and the like, but the water resistance and weather resistance of the coating film are insufficient. Also, because of its high viscosity, it cannot be spray painted,
It is difficult to paint on vertical parts such as walls, so it is not suitable as an outdoor paint. It has been proposed to use dimer diol as a part of the raw material for the purpose of improving the water resistance of the polyurethane coating (Japanese Patent Application Laid-Open No. 8-269158). However, in this polyurethane coating, since the compatibility between the dimer diol and other components is low, there are problems in curability and coating film appearance. On the other hand, it has been reported that use of dimer diol as a main component of a polyol component can provide a coating film having excellent water resistance and salt water shielding properties (Japanese Patent Application Nos. 9-113585 and 9-20519).
0). These coating compositions give a coating film having excellent water resistance, but have insufficient flexibility and substrate-following property, and the viscosity of the coating liquid is rather high, so that coating properties are difficult.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and exhibits a low-viscosity liquid at ordinary temperature, has excellent compatibility with a coating liquid, has a soft coating film, and is free from cracks on a substrate. An object of the present invention is to provide a solvent-free two-pack type urethane paint that can sufficiently follow. Furthermore, an object of the present invention is to provide a raw material component that can be suitably used in preparing the above-mentioned paint.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the above object, and found that a polyol mixture containing a diol compound obtained by adding an alkylene oxide to a dimer diol as a main component is: The present inventors have found that the object can be achieved by combining with a specific polyisocyanate compound, and completed the present invention. That is, the present invention comprises a diol represented by the following general formula (1) and another polyol, and contains 50% by weight or more of the diol represented by the general formula (1) based on the total amount of all polyols. And the viscosity at 25 ° C. is 2000 cp
s or lower viscosity polyol mixture. HO- (X-O) m-Z-O- (X-O) n-H (1) (wherein, X is an alkylene group having 2 to 4 carbon atoms, Z is a dimer diol residue, and m and n are The same or different integer of 0 or more is shown, and 2 ≦ m + n ≦ 40.) Hereinafter, the present invention will be described in more detail.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polyol mixture of the present invention contains at least 50% by weight of a diol compound represented by the above general formula (1) (hereinafter referred to as "diol compound (1)") as an essential component. And a viscosity at 25 ° C. of 2000
It is a composition of cps or less. When the amount of the diol compound (1) in the total polyol mixture is less than 50% by weight, the liquid viscosity increases, the coating property decreases, and the coating film tends to become cloudy due to poor compatibility. The preferred amount of the diol compound (1) is at least 65% by weight. The diol compound (1) used in the present invention is an alkylene oxide adduct of a dimer diol, wherein X in the above general formula (1) represents an ethylene group, a 1-methyl-ethylene group, or a 2-methyl-ethylene group. , N-propylene group, n-butylene group, isobutylene group and the like. Among them, it is preferable that X is an ethylene group and / or a propylene group, because it is effective for compatibility with other components and reduction in viscosity. Ethylene groups are more preferred because of their high reactivity with polyisocyanates. The addition amount of the oxyalkylene unit of the diol compound (1) is 2 or more and 40 or less on average of m + n. Preferably, the average value of m + n is 2 or more and 20 or less. If the added amount is less than 2, the liquid viscosity increases and poor compatibility is likely to occur, and if it exceeds 20, the water resistance decreases.

[0006] The production method of the diol compound (1) is not particularly limited, and any one produced by any method may be used. Specifically, it may be manufactured according to the method described in Japanese Patent Application No. 9-205190. The dimer diol used as a raw material of the diol compound (1) is a C36 fatty acid obtained by hydrogenating (preferably completely hydrogenating) a dimer acid obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms. Diol. It has the characteristic that it exhibits a liquid state at normal temperature due to the action of a long-chain branched alkyl group in the molecule, and becomes a coating film having excellent water resistance when polymerized. Dimer diol is commercially available, and is sold, for example, as Pespol HP-1000 (trade name) manufactured by Toagosei Co., Ltd.

In the polydiol mixture of the present invention, other polyfunctional alcohol components can be used as auxiliary components only in an amount of less than 50% by weight, and the viscosity at 25 ° C. of the polyol mixture is kept at 2000 cps or less. It can be used within the range of dripping. Specific examples of the polyfunctional alcohol include dimer diol, polyester diol having a dimer acid unit as a main component, polyester diol having an adipic acid unit as a main component, polycaprolactone diol, polyether diols including polytetramethylene diol, High molecular weight diols such as polycarbonate diol and polybutadiene diol, ethylene glycol, propylene glycol, 1,4-butanediol, 3-methylpentanediol, 1,6-hexanediol, cyclohexanedimethanol, neopentylglycol, 2,2,4 Trimethyl-1,3-pentanediol, 2-methyl-1,8-octanediol,
Examples thereof include aliphatic or alicyclic diols such as 1,9-nonanediol, and trifunctional or higher polyols such as trimethylolpropane, pentaerythritol, glycerin, and polycaprolactone triol. These polyols can be used alone or in combination of two or more.

[0008] In the polyol mixture of the present invention,
The total amount of the dimer diol residue and the dimer diol itself of the diol compound (1) is preferably from 40 to 85% by weight. If the dimer diol content is less than 40% by weight, the water resistance of the coating film will be insufficient, and if it exceeds 85% by weight, the viscosity of the coating material will increase and the coatability will decrease. When the above polyol mixture is used as a raw material for a polyurethane coating, the hydroxyl value of the polyol mixture is 50 to 300.
It is preferably in the range of mgKOH / g. More preferably, the hydroxyl value of the polyol mixture is 100 to 250 mg.
KOH / g. If the hydroxyl value is less than 50 mgKOH / g, the curability is low and tack tends to remain on the coating film. When the hydroxyl value exceeds 300 mgKOH / g, the flexibility is lowered and the followability to the base is lowered.

The polyisocyanate component used in the polyurethane coating of the present invention has a viscosity at 25.degree.
It is an aliphatic, alicyclic, or aromatic bifunctional and / or trifunctional or higher isocyanate of ps or less. Among them, polyisocyanates having a viscosity of 200 to 2000 cps at 25 ° C. are preferred, and 300 to 1500 cp, from the viewpoints of prevention of dripping during coating and compatibility with the polyol component.
The polyisocyanate of s is more preferred. When the polyurethane paint is required to have weather resistance, an aliphatic polyisocyanate and / or an alicyclic polyisocyanate can be preferably used. In addition, the polyisocyanate of the present invention can be used alone or in combination of two or more.
Specific examples of the polyisocyanate preferably used in the present invention include hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexyltan-4,4
'-Diisocyanate, such as aliphatic or alicyclic diisocyanate; isocyanurate ring-containing condensate or burette type condensate of the above diisocyanate compound, isocyanate-terminated urethane prepolymer obtained by reacting the above diisocyanate compound with alkylene diol, Examples thereof include isocyanate-terminated urethane prepolymers obtained by reacting the above-mentioned diisocyanate compound with polyether diol or polyester diol. These polyisocyanates can be used alone or in combination of two or more.

The mixing ratio of the polyol mixture and the polyisocyanate component in the polyurethane coating may be such that the polyurethane is smoothly formed by the reaction between the two. Generally, one equivalent of the hydroxyl group of the polyol mixture is mixed with the polyisocyanate component. The isocyanate groups of the components are mixed at a ratio of 0.9 to 1.2. Before the polyurethane paint of the present invention is used for coating, it is preferable to store the polyol mixture and the polyisocyanate component in a separated state, that is, in the form of a two-pack paint.
At the time of coating, both are mixed and used in the ratio described above.
The polyurethane paint of the present invention may use one or more catalysts for accelerating the urethanization reaction, if necessary. Preferred examples of the catalyst include metal-based catalysts such as dibutyltin dilaurate, dibutyltin acetate, tin octylate, lead octylate, and zirconium complex. The amount of the catalyst to be added is generally preferably 100 to 1200 ppm based on the polyurethane coating. It is preferable that the catalyst is previously mixed with the polyol mixture or added at the same time when the polyol mixture and the polyisocyanate component are mixed. The polyurethane paint which is a mixture of the above-mentioned polyol mixture and polyisocyanate component exhibits a low-viscosity liquid at ordinary temperature, so that it is easy to handle and has excellent coatability. Therefore, it is not usually necessary to dilute with a solvent, and it can be directly applied to a substrate as it is. Although an organic solvent can be used if necessary, it is preferable that the amount used is controlled to 10% or less based on the total amount of the polyol mixture and the polyisocyanate component. If the amount used exceeds 10%, safety during work is impaired and the environment is polluted.

Specific examples of the use of an organic solvent include metal ethyl ketone, ethyl acetate, butyl acetate, toluene, xylene, N-methylpyrrolidone, butyl carbitol acetate, a hydrocarbon solvent, and two or more of these solvents. Mixed solvents and the like can be mentioned. In addition, the polyurethane paint of the present invention may contain, if necessary, various known additives such as a leveling agent, an antifoaming agent, a desiccant, a matting agent, a filler, a pigment, a pigment dispersant, and an ultraviolet absorber.
Species or two or more species may be contained. In coating with the polyurethane paint of the present invention, a method is employed in which the above-mentioned polyol mixture, a polyisocyanate component and, if necessary, a catalyst and other additives are mixed, and the mixed solution is applied to a substrate. You. The coating operation is preferably performed within 2 hours after mixing the above-mentioned components. After coating on the substrate, it usually cures within one week at room temperature and is excellent in water resistance, salt water resistance, appearance, weather resistance, mechanical properties, adhesion to the substrate, and ability to follow the crack of the substrate. Is formed.

The polyurethane paint of the present invention can be effectively used as a paint for various substrates such as concrete, mortar, metal, wood, plastic and ceramics. In particular, the polyurethane paint of the present invention has excellent water resistance, weather resistance, flexibility, and mechanical properties, and is therefore often used for outdoor paints that are often exposed to weather, moisture, sunlight, and the like.
For example, it can be suitably used as a paint for concrete structures, bridges, metal plates, steel frames and the like. The polyurethane paint of the present invention may be applied directly to the substrate as it is, or may be applied after the substrate has been primer-coated. The coating method is not particularly limited, and for example, a coating method such as spray coating, roller coating, dip coating, or brush coating can be employed. Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. All parts of the components in each example are parts by weight.

Reference Example 1 Production of Diol Compound (1) (Production of Abbreviation "DDE-1") In a nitrogen-purged autoclave, dimer diol (hydroxyl value: 197 mg KOH / g, "PESPOL HP" manufactured by Toagosei Co., Ltd.) −1000 ”) 100.0 g (0.1
87 mol) and 52.4 g (0.4%) of 40% potassium hydroxide.
374 mol), and a dehydration reaction was carried out at a temperature of 100 ° C. and a pressure of 5 mmHg for 3 hours to obtain a reaction product having a water content of 100 ppm or less. The reaction is heated to a temperature of 110 DEG-120 DEG C. and 50.0 g (1.136 mol) of ethylene oxide are added under pressure (5 kg / cm @ 2) over 4 hours.
Was gradually added to react. Cooling the product to 60 ° C.
Unreacted ethylene oxide was removed under a reduced pressure of 10 mmHg. The obtained reaction product is neutralized with hydrochloric acid, then dehydrated and filtered to obtain a diol compound obtained by adding ethylene oxide to a liquid dimer diol (abbreviated as DDE-1).
144 g were obtained. (Hydroxyl value 137mgKOH / mg,
1H-NMR analysis revealed that this compound was a diol with 6 moles of ethylene oxide added per mole of dimer diol.

Reference Example 2 Production of Diol Compound (1) (Production of Abbreviation "DDE-2") The amount of ethylene oxide used was 100.0 g (2.2).
73 mol), and 192 g of a diol compound obtained by adding ethylene oxide to dimer diol (abbreviated as DDE-2) was obtained in the same manner as in Reference Example 1. (Hydroxyl value: 109 mgKOH / mg, number average molecular weight: about 1030) As a result of 1H-NMR analysis, it was found that 11 mol of ethylene oxide was added to 1 mol of dimer diol.

[0015]

Examples 1-4 and Comparative Examples 1-2 The polyol components (dimer diol, DDE-1, DDE-2 and 1,4-butanediol synthesized in Reference Examples) and polyisocyanate at the ratios shown in Table 1 The components [Duranate D-101 manufactured by Asahi Kasei Corporation, NC11 manufactured by Meiwa Yuka Kogyo Co., Ltd.] and dibutyltin dilaurate were mixed to prepare respective polyurethane paints. About 1 of this polyurethane paint
1 g was poured into a 10 cm × 10 cm formwork and left at room temperature for 7 days to form a polyurethane film having a thickness of about 1 mm. The appearance (transparency) of this film was visually evaluated. In addition, a tensile test was performed according to JIS A6021 (using a dumbbell-shaped No. 3 test piece at a tensile speed of 50%).
0 mm / min). The results are shown in Table 1. The viscosities in the table are the results obtained by separately preparing a mixed solution to which dibutyltin dilaurate was not added and measuring with a BM-type rotational viscometer (25 ° C., rotor No. 4).

[0016]

[Table 1]

The abbreviations in Table 1 indicate the following compounds, respectively. DDE-1: diol synthesized in Reference Example 1 DDE-2: diol synthesized in Reference Example 1 DD: Dimer diol [HP-1 manufactured by Toagosei Co., Ltd.
000] 1,4-BD: 1,4-butanediol DBTDL: Dibutyltin dilaurate D-101: Hexamethylene diisocyanate-based bifunctional fluoropolymer NC-11: Isophorone diisocyanate-based bifunctional fluoropolymer

[0018]

As can be seen from the results of Examples and Comparative Examples, the coating composition of the present invention usually has a liquid viscosity of 1000 cp.
s or less, a general-purpose coating machine such as an airless sprayer can be used, and coating on a vertical surface is easy. Further, the addition of ethylene oxide improves the compatibility with the isocyanate compound and the chain extender, and the cured coating film has excellent transparency. In terms of physical properties of the coating film, it has high elongation at break and excellent flexibility, so that it has excellent ability to follow the cracks of the base material and has optimal performance as a waterproof coating film. Further, the coating film formed from the polyurethane coating material of the present invention has excellent water resistance and weather resistance, and thus can be effectively used as an outdoor coating material.

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 4J034 BA08 CA01 CA03 CA04 CB03 CB04 CB05 CB07 CC01 CC03 CC23 CC26 CC45 CC52 CC62 CC65 DA01 DB03 DB04 DB05 DB07 DC12 DC35 DC37 DC43 DC50 DG01 DG02 DG03 DG04 DG05 DG14 HA01 HA02 HA06 HA13 HA14 HB07 HB11 HC01 HC02 HC03 HC11 HC17 HC46 HC52 HC61 HC63 HC64 HC68 HC70 HC71 HC73 QA05 QB13 QC05 RA07 4J038 DG051 GA03 LA03 MA15 NA01 NA04 NA12 NA13 NA23 PB05 PC04

Claims (3)

[Claims] 1. A diol represented by the following general formula (1) and another polyol, wherein the diol represented by the general formula (1) is contained in an amount of 50% by weight or more based on the total amount of all polyols. And the viscosity at 25 ° C is 2000c
A low viscosity polyol mixture that is less than or equal to ps. HO- (X-O) m-Z-O- (X-O) n-H (1) (wherein, X is an alkylene group having 2 to 4 carbon atoms, Z is a dimer diol residue, and m and n are It represents the same or different integer of 0 or more, and 2 ≦ m + n ≦ 40.) 2. The total amount of dimer diol and the dimer diol residue (-Z-) in the diol compound of the general formula (1) is 40 to 8 based on the total amount of all polyols.
The low viscosity polyol mixture according to claim 1, which is 5% by weight. 3. A two-pack polyurethane paint comprising the low-viscosity polyol mixture according to claim 1 or 2 and a polyisocyanate having a viscosity at 25 ° C. of 2000 cps or less.