JPS6249289B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to polyurethane resins useful in the manufacture of polyurethane products such as films, coatings, hardeners, adhesives, and in particular in the manufacture of polyurethane resin coatings. The isocyanate compound used in the present invention belongs to a non-yellowing type, which is one of the major features of the present invention. These non-yellowing isocyanate compounds exhibit their properties in the field of polyurethane paints, and are used in vehicles such as automobiles, railway cars, and containers, aircraft, seamless floors, coil coatings, ships, as well as woodworking, plywood, aluminum sash, etc. It is used in a variety of fields, including building materials and plastics, and is well received. Isocyanate compounds are extremely reactive chemical substances, so it is extremely dangerous for people with allergies or weak respiratory systems to use them. For example, the ultimate atmospheric concentration of monomers such as toluene diisocyanate and diphenylmethane diisocyanate is
The level was decided at 0.02 ppm by a committee of the U.S. government-affiliated Council of Industrial Hygiene Experts. For these reasons,
In polyurethane paints, the above-mentioned isocyanate monomers are rarely used as they are, except in special cases, and are usually modified into prepolymers (adducts) added to trimethylolpropane, ethylene glycol, etc. This modification has the effect of lowering the vapor pressure, thereby reducing toxicity and odor, as well as adjusting reactivity and making coatings more diverse. Although these prepolymer adducts have extremely low vapor pressures at room temperature, it is industrially extremely difficult to completely remove the isocyanate monomer from the prepolymer adducts, and the monomer concentration in commercially available polyisocyanates is usually within a range of 0.7% or less. It is contained in. However, on the other hand, highly toxic diisocyanates are present in commercially available isocyanate prepolymers, albeit in trace amounts, and a strong irritating odor can be felt during paint formulation and painting operations, leading to respiratory illnesses specific to isocyanates. Many people complain of symptoms, and as the uses of polyurethane products increase, this issue has come under scrutiny. In particular, isocyanate compounds are said to release diisocyanates, so-called highly toxic monomers, depending on the storage conditions during storage, which is a cause for concern for engineers and workers. Under these circumstances, work environments are being improved by providing sufficient ventilation to prevent workers from directly inhaling isocyanate compounds, but the current situation is that this is still not sufficient. In view of these circumstances, the present inventors have made earnest efforts to develop a polyurethane resin using a trifunctional isocyanate compound that does not contain any highly toxic volatile monomers and has no irritating odor, and has thus arrived at the present invention. That is, the present invention provides: (1) a polyol and a 1.8- represented by the formula ();
A polyurethane resin produced by reacting diisocyanate-4-isocyanate with methyloctane. and (2) polyol and 1.8 represented by the above formula ()
- A coating composition containing as a main component a polyurethane resin obtained by reacting diisocyanate-4-isocyanate with methyloctane. It is. 1,8-Diisocyanate-4-isocyanate methyloctane, which is a trifunctional isocyanate compound used in the present invention, is a new compound having a chemical structure represented by the formula (). This compound has a linear hydrocarbon chain as its molecular skeleton, one isocyanate group is bonded to each of the primary carbon atoms at both ends, and
It is a compound with an isocyanate methyl group bonded to the position thereof, and its boiling point is 129-132°C/0.1 mmHg, and it is a colorless liquid substance with extremely good fluidity at around room temperature. This compound has the advantageous property that it has a vapor pressure close to room temperature, is not irritating to the human body, and can be safely handled. Moreover, this triisocyanate has a high isocyanate content of 50%. This value is a high value that cannot be obtained with conventionally known polyisocyanates that are odorless and have low vapor pressure at around room temperature. Furthermore, this compound has an extremely low viscosity at room temperature, so there is no need to lower the viscosity with a diluent as with existing products, so it can be used practically as a triisocyanate with a high isocyanate content. It is. On the other hand, the term polyol as used in the present invention includes compounds or polymers containing two or more hydroxyl groups per molecule. For example, diols, triols, tetraols, pentols, hexitols and mixtures thereof, as well as polyesters, polyethers, polyester polyols, polymer polyols containing two or more hydroxyl groups per molecule; You can also use Specifically, the following compounds can be mentioned. Diol ethylene glycol, propylene glycol,
β・β′-dihydroxydiethyl ether (diethylene glycol), dipropylene glycol,
1,4-butylene glycol, 1,3-butylene glycol, polyethylene glycol, polypropylene glycol, polypropylene-polyethylene glycol, polybutylene glycol polyol Glycerin, trimethylolpropane, pentaerythritol, sorbitol, 2-methylglucoside, 1,2, Compound polyether polyol having two or more hydroxyl groups in one molecule such as 6-hexanetriol It is prepared by adding propylene oxide, ethylene oxide, etc. to a polyhydric alcohol such as glycerin or propylene glycol. It also includes polyether polyols rich in hydroxyl groups, which are made by reacting ethylene oxide or propylene oxide with a polyfunctional compound such as ethylenediamine or ethanolamine. Polyester polyols Synthesized by the condensation reaction of carboxylic acids such as adipic acid, dimer acid, phthalic anhydride, and isophthalic acid with diols and triols such as ethylene glycol, diethylene glycol, propylene glycol, trimethylolpropane, and glycerin. Polymer polyol It can be prepared by copolymerizing a polymerizable monomer having one or more hydroxyl groups in one molecule and another monomer that can be copolymerized therewith. A polymerizable monomer having one or more hydroxyl groups in one molecule is represented by the following general formula. (In this formula, n = 1, 2 or 3 R ₁ : Hydrogen or methyl R ₂ : Substituted or unsubstituted hydrocarbon residue having 2 to 12 carbon atoms) For example, 2-hydroxyethyl acrylate,
2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-methacrylate
Hydroxyethyl, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxypentyl methacrylate, methacrylic acid monoester of glycerin, acrylic acid monoester of trimethylolpropane These include esters, methacrylic acid monoesters, 2-hydroxy-3-chloropropyl acrylate, 2-hydroxy-3-chloropropyl methacrylate, and the like. Among the various monomers, the most preferable ones are:
Hydroxyalkyl (meth)acrylates include 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl methacrylate, and other monomers include methyl acrylate, ethyl acrylate, and acrylic acid. Examples include butyl acid, methyl methacrylate, butyl methacrylate, lauryl methacrylate, acrylic acid, methacrylic acid, styrene, acrylamide, and vinyl acetate. Further, in order to prepare a suitable polymer polyol, it is preferable to select the amount of each monomer to be used as follows. A Hydroxyalkyl (meth)acrylate
5-30% by weight B Acrylic acid alkyl ester or (and) methacrylic acid alkyl ester
50 to 95% by weight C Other monomers as necessary 0 to 50% by weight D Acrylic acid or methacrylic acid 0 to 10% by weight In the above, if the amount of hydroxyalkyl (meth)acrylate is less than 5% by weight, it may be difficult to combine with the isocyanate compound. The degree of crosslinking caused by the reaction becomes too small, making it impossible to obtain a film with the expected performance. A polymer polyol obtained by copolymerizing the monomers described above can be produced by known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization, but solution polymerization is usually carried out. Although various polyols have been specifically exemplified above, the polyol of the present invention is not limited to these, and any polyol that can react with the trifunctional isocyanate compound used in the present invention to form a urethane bond can be used. can be used, and various combinations can also be selected. The preferred hydroxyl value for the above various polyols is
The range is from 20 to 1000, particularly preferably from 20 to 500. In addition, especially for high solids type compositions,
The 1000 range is excellent. If the hydroxyl value is 20 or less, the degree of crosslinking due to the reaction with the isocyanate compound will be small, and the various performances required for non-yellowing polyurethane applications, particularly solvent resistance, water resistance, and weather resistance, will not be satisfied. On the other hand, the hydroxyl value
On the other hand, when it is more than 1000, the degree of crosslinking becomes excessive, and the mechanical properties of the crosslinked film are significantly reduced, making it brittle and having poor impact resistance, which is not preferable. The polyurethane resin of the present invention is synthesized from the various polyols described above and the trifunctional isocyanate compound described above, and is used to form films, coatings, elastomers,
It can be used to make a variety of polyurethane products including foams, hardeners, adhesives, and the like. By adjusting the type of polyol and the NCO/OH ratio in the composition, various performance and physical properties such as film strength, flexibility, chemical resistance, and solvent resistance can be changed over a wide range. It can be used for different purposes. The NCO/OH ratio (molar ratio) in the composition of the present invention is
Compositions in the range 0.5 to 2.0 are suitable for the production of films and coatings. NCO/OH ratios of 0.5 to 1.2 are particularly suitable for polyurethane paints.
NCO/OH ratios of 0.5 to 1.0 are useful in the electrical insulation field, encapsulation field, and cast products. In addition, when the NCO/OH ratio is 0.1 to 0.7, it is preferable for producing advanced adhesives or hardeners;
If the NCO/OH ratio is large, it is suitable for foam production. Foaming can be carried out by introducing an amount of water or a blowing agent into the reaction product by known foaming techniques. The polyurethane resin of the present invention is particularly useful for polyurethane resin coatings. Polyurethane paints generally have excellent adhesion to various objects, balance of hardness and flexibility, crack resistance, water resistance, chemical resistance, gloss, etc., and the polyurethane resin paint obtained by the present invention also has excellent properties. In addition to having excellent performance, it also has superior features compared to commercially available polyurethane resin paints, which will be described later. All of these features depend on the trifunctional isocyanate compound used in the present invention, and are features not found in commercially available non-yellowing polyisocyanates (prepolymers or adducts). Comparing the performance of polyurethane resin paints with the same polyol (constant NCO/OH ratio) using commercially available non-yellowing polyisocyanates, the characteristics of the paints of the present invention are as follows. (1) Low toxicity (2) Easily improves the appearance of the paint film. (3) The coating film has particularly excellent acid resistance and water resistance. (4) It can contribute to high solidity. The polyurethane resin paint obtained by the present invention can be used in a two-pack type, a one-pack type, etc. by a commonly used method. Incidentally, the solvent used in the polyurethane resin coating must naturally have no active hydrogen atoms, and the same applies to the composition of the present invention. Therefore, solvents that react with isocyanate groups cannot be used as solvents for dissolving polyols. For example, those with basic nitrogen atoms such as alcohols, dimethylformamide, and pyridine should be avoided. Examples of solvents that can be used in the present invention include the following. Hydrocarbon solvents Benzene, toluene, xylene, aromatic naphtha ester solvents Ethyl acetate, butyl acetate, cellosolve, hexyl acetate, amyl acetate, ethyl propionate, butyl propionate, Ketone solvents Acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl Isobutyl ketone, diethyl ketone, cyclohexanone glycol ester solvent Ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate In the above solution, the non-polar hydrocarbon solvent is used as a solvent for the polyol component or isocyanate compound. In some cases, it may result in a non-uniform or opaque solution, making it unsuitable for use alone. In addition, esters are the most commonly used in terms of their solubility, but care must be taken as impurities such as alcohol, acid, and water are likely to be mixed in. The coating composition of the present invention can be applied to an object by a conventional method such as spray coating, brush coating, dip coating, or roller coating. Additionally, commonly used pigments, plasticizers, and small amounts of additives added during coating and painting can also be used within their customary amounts. Similar to solvents, when selecting pigments, it is necessary to pay attention not only to various properties but also to water content, and extender pigments in particular have a high water adsorption capacity. Catalysts can also be used to accelerate drying and curing. For example, tertiary amines such as dimethylethanolamine and triethylenediamine, and organic tin salts such as stannath octoate and dibutyltin dilaurate can be used. The reaction temperature for producing polyurethane products is preferably in the range of 20 to 160°C. The preferred reaction is between isocyanate groups and hydroxyl groups to form urethane bonds. However, reactions between isocyanate groups and active hydrogen atoms other than hydroxyl groups can also be carried out. Examples of such active hydrogen donors include amines, acids, substituted ureas, urethanes, amides, and the like. Specifically, the isocyanate group further reacts at a relatively high temperature with the -NH group of the urethane bond formed by the reaction with the hydroxyl group to form an allophanate bond.
Similarly, a biuret bond is formed from a urea bond and an isocyanate group, and an acylurea bond is formed from an amide bond and an isocyanate group. In this way a wide variety of reactions are possible,
These can be used depending on the intended use. If necessary, antioxidants, pigments, plasticizers,
Adjuvants commonly used in the art, such as catalysts, surfactants, etc., can be added to the reactants. Next, the present invention will be specifically explained using Examples and Comparative Examples. Parts used herein refer to parts by weight. Example 1 A reaction vessel equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet tube was sealed with nitrogen, and then xylol was added.
50 parts and 50 parts of butyl acetate were added, and the temperature was raised to 90-95°C. A mixture consisting of 34.0 parts of styrene, 38.0 parts of n-butyl acrylate, 23.4 parts of 2-hydroxyethyl methacrylate, 0.4 parts of acrylic acid, and 1.2 parts of azobisisobutyronitrile was continuously dropped into the reaction vessel over 3 hours. A polymerization reaction was carried out. After the monomer mixture was added dropwise, the mixture was heated and stirred for 1 hour, and then 0.7 part of azobisisobutyronitrile was added every 30 minutes a total of 4 times, and the reaction was further stirred for 1 hour to complete the reaction. The resin solution (acrylic polyol) thus prepared was colorless and transparent, had a Gardner bubble viscosity (at 25° C.) of T to U, and a nonvolatile content of 50%. The molecular weight (n) was 14,500, the hydroxyl value was 50, and the calculated average number of hydroxyl groups in one molecule was 12.9. This resin solution and 1,8-diisocyanate-4
-Isocyanate methyl octane was uniformly mixed so that hydroxyl groups and isocyanate groups were equal in amount. A mixed thinner of equal amounts of toluene and cellosolve acetate was added to this mixture, and the mixture was adjusted to 18 seconds using a #4 food cup. This diluted paint was spray-painted onto a polished steel plate coated with Primer Surf Acer No. 114 (manufactured by Kaisai Paint Co., Ltd.) so that the film thickness after drying was approximately 40μ, and cured at room temperature (23℃) for 7 days. I let it happen. As shown in Table 1, the resulting coating film is tough and has excellent acid resistance and hot water resistance. Comparative Example 1 Paints and coatings compared to Example 1, in which "Desmodur N-75" (hexamethylene diisocyanate biuret type manufactured by Bayer) was used instead of 1,8-diisocyanate-4-isocyanate methyloctane. The performance is shown in Table 1. The paint was made by adding titanium oxide R-930 (manufactured by Ishihara Sangyo Co., Ltd.) to the acrylic polyol prepared in Example 1.
A white enamel paint was prepared by thoroughly stirring and pulverizing the mixture using a paint conditioner. The resulting enamel was blended with equal amounts of hydroxyl groups and isocyanate groups, and a paint was diluted for 18 seconds using a #4 food cup in the same manner as in Example 1, and spray-painted onto a mild steel plate. The paint made from the composition of the present invention has a high solids content when applied, so it is suitable for saving resources, and it is also suitable for “Desmodur
It has practical performance on the same level as N-75'' type coatings, and has particularly excellent acid resistance.

【table】

[Table] Example 2 A polyester polyol is produced as follows. Neopentyl glycol 126.9 parts Trimethylolpropane 22.1 parts Adipic acid 72.3 parts Isophthalic acid 123.2 parts This mixture is placed in a reaction vessel and heated and stirred at 200°C for 30 minutes. Next, heating and stirring were continued while distilling water at a temperature of 220°C until reaching a foam viscosity F (solid content in methyl ethyl ketone: 60%), an acid value of approximately 10, and a hydroxyl value of approximately 100 (approximately 15 hours). . Methyl ethyl ketone was added to the reactant while cooling it to adjust the solid content to 60%, thereby preparing a polyester polyol solution. Next, 1,8-diisocyanate-4-isocyanate methyloctane is added to this polyol solution so that the hydroxyl groups and isocyanate groups are equal in amount, and mixed uniformly. The film obtained by coating and curing this mixture has excellent gloss and extremely good mechanical properties.

Claims (1)

[Claims] 1. Polyol and 1,8-diisocyanate-4
- A polyurethane resin produced by reacting isocyanate with methyloctane. 2 Polyol and 1,8-diisocyanate-4
- A coating composition whose main component is a polyurethane resin produced by reacting isocyanate with methyloctane.