JP4792736B2 - Organic polyisocyanate composition, method for producing organic polyisocyanate, adhesive composition, and coating composition - Google Patents

Description

  The present invention relates to an organic polyisocyanate composition excellent in storage stability, which is less susceptible to viscosity increase and coloring over time, and a purification method, an adhesive composition and a coating composition for obtaining the same.

  Since polyisocyanate compounds have very high reactivity of isocyanate groups, they easily react with compounds containing active hydrogen groups such as polyols and amines (hereinafter referred to as active hydrogen group-containing compounds) even at room temperature. The obtained polyurethane compound has excellent performance such as adhesiveness, abrasion resistance, chemical resistance and flexibility even at room temperature curing, not only foaming fields such as hard and flexible polyurethane foam, but also elastomers, synthetic It is also widely used in non-foaming fields such as leather, spandex, adhesives and paints.

  Two-component polyurethane adhesives and paints are composed of active hydrogen group-containing compounds as main ingredients, generally polyester polyols, oil-modified polyester polyols, acrylic polyols, etc., and polyisocyanate compounds having isocyanate groups as curing agents. Become. Curing agents include diphenylmethane diisocyanate (hereinafter referred to as MDI) having two benzene rings and two isocyanate groups in one molecule, and MDI polynuclear condensation having three or more benzene rings and isocyanate groups in one molecule. MDI-based mixtures (hereinafter referred to as polymeric MDI), urethane-modified products such as tolylene diisocyanate (hereinafter referred to as TDI) and hexamethylene diisocyanate (hereinafter referred to as HDI), and isocyanates An isocyanurate modified product (hereinafter referred to as trimer form) obtained by nurate ring formation polymerization (hereinafter referred to as trimerization) is used. Furthermore, isocyanate group-terminated urethane prepolymers using these are widely used. Aromatic diisocyanates such as MDI and TDI are widely used from the viewpoint of economy when it is not necessary to place importance on the weather resistance of the adhesive layer or coating film.

  Generally, an organic polyisocyanate composition is obtained by reacting an amino compound with phosgene (phosgenation) to convert an amino group into an isocyanate group. For example, in the case of an MDI organic polyisocyanate composition, aniline and formaldehyde are generally condensed to obtain polyamine condensation mixtures having different degrees of polymerization, and then reacted with phosgene (phosgenation) to form amino groups. It is converted into an isocyanate group and then obtained by distillation separation if necessary.

  Industrial production equipment for organic polyisocyanate compositions generally uses metal equipment mainly composed of iron or stainless steel in terms of cost and maintenance, and due to corrosion and / or erosion of equipment during the production process. The metal component may elute into the polyisocyanate compound. Among them, especially the mixing of iron often leads to an increase in viscosity and an increase in coloring of the organic polyisocyanate composition, and often causes deterioration in storage stability.

  On the other hand, for example, in the case of an MDI organic polyisocyanate composition, the acidity caused by chlorine compounds such as amine hydrochloride, carbamic acid chloride, benzyl chloride, etc. generated in the phosgenation step of the polyamine condensation mixture is not limited to the isocyanate group itself. In addition, it is a factor that suppresses or delays the reaction even in the combination with the active hydrogen group-containing compound, but it is also a factor that causes an increase in coloring and corrosion of equipment and containers. In order to suppress an increase in the viscosity of the organic polyisocyanate composition over time, it is preferable that the content of acidity is high. However, if the content is high, the activity of the organic polyisocyanate and the active agent in two-component polyurethane paints and adhesives The curing reaction with the hydrogen group-containing compound becomes too slow, resulting in poor curing, and it is difficult to obtain performance as a paint or an adhesive. Furthermore, since it causes the coloring increase and the corrosion of facilities and containers, it is preferable that the acidity is as low as possible.

In order to improve these points, various techniques have been disclosed. For example, in Patent Document 1, as a method of reducing the iron content in diphenylmethane diisocyanate or diphenylmethane diisocyanate-based polyisocyanate mixture, treatment with one or more microporous adsorbents having an internal surface area of at least 100 m ² / g A method is disclosed. Patent Document 2 discloses a method for purifying an organic isocyanate compound that does not contain impurities, and includes a method for distillation by heating in the presence of a Lewis acid such as ferrous chloride, ferric chloride, or zinc chloride. In Patent Document 3, in the production process of polymethylene polyphenyl polyisocyanate, after phosgenation, excess phosgene is removed, and then a hydrazine compound is added in any step prior to the step of removing the inert solvent. Has been proposed. Patent Document 4 proposes a method of adding a low molecular weight alkanol or a polyhydric alcohol after phosgenation. Patent Document 5 proposes a method of adding water and a monovalent or polyvalent polyoxyalkylene alcohol after phosgenation.

  However, the technique of Patent Document 1 is a technique related to the reduction of only the iron content, and the technique of achieving reduction in acidity caused by chlorine compounds that cause color increase and corrosion of equipment and containers in parallel. is not. On the other hand, the technique of Patent Document 2 is intended to remove hydrolyzable chlorine, and there is no problem with distillate. However, the metal residue in the distillation residue is rather increased, and it can withstand actual use. It's not good. In the technique of Patent Document 3, the hydrazine compound used is present in the obtained polyisocyanate, and there is a possibility that the viscosity will increase with time. In Patent Document 4 and Patent Document 5, although the distillation residue is reduced in color due to the presence of a reaction product with alcohol, the distillate does not lead to color reduction because the reaction product does not exist.

Japanese Patent Application Laid-Open No. 08-99946 JP 2003-55333 A Japanese Patent Laid-Open No. 11-240858 Japanese Patent Laid-Open No. 04-211641 JP 09-1000026 A

  In order to obtain an organic polyisocyanate composition with excellent storage stability, the present invention solves the above problems, i.e., there is little change in viscosity increase and coloring increase over time. The object is to provide a purified organic polyisocyanate composition and purification method, and an adhesive composition and a coating composition using the organic polyisocyanate composition. .

  In solving the above-mentioned problems, the present inventors have conducted extensive studies, and as a result, not only the iron content that causes an increase in viscosity and coloration over time of the organic polyisocyanate composition, but also the acidity in parallel. As a refining method for reducing the amount, it has been found that it is effective to use a filter medium or adsorbent having a specific quality, and the present invention has been achieved.

That is, according to the present invention,
(A) 20 to 70% by mass of diphenylmethane diisocyanate each having two benzene rings and two isocyanate groups in one molecule, and
(B) Containing 80 to 30% by mass of diphenylmethane diisocyanate polynuclear condensate containing a benzene ring and an isocyanate group in one molecule and having an NCO content in the range of 5 to 32% by mass in terms of solid content, and containing iron A crude polyisocyanate having an acidity of more than 60 ppm and an acidity of more than 200 ppm ,
(C) The activated iron or diatomaceous earth having a pH of 7.5 to 11.5 and an average particle size of 10 to 200 μm is adsorbed with a suspended iron element and a chlorine compound dissolved in the polyisocyanate, and contains iron. the 60ppm or less, and the acidity and 200ppm or less,
A polyisocyanate composition can be provided.

Moreover, according to the present invention,
(A) 20 to 70% by mass of diphenylmethane diisocyanate each having two benzene rings and two isocyanate groups in one molecule, and
(B) containing a benzene ring and isocyanate groups in one molecule, a diphenylmethane diisocyanate Natick preparative polynuclear condensates range of 5 to 32 wt% NCO content as solid matter containing 80 to 30 wt%, iron An isocyanate group-terminated urethane prepolymer obtained by reacting a crude polyisocyanate having a content exceeding 60 ppm and an acidity exceeding 200 ppm with a polyol selected from polypropylene glycol or polyethylene glycol methyl ether,
(C) The activated iron or diatomaceous earth having a pH of 7.5 to 11.5 and an average particle size of 10 to 200 μm is adsorbed with a suspended iron element and a chlorine compound dissolved in the polyisocyanate, and contains iron. Can be provided, and a polyisocyanate composition having an acidity of 200 ppm or less can be provided.

Furthermore, according to the present invention,
(A) 20 to 70% by mass of diphenylmethane diisocyanate each having two benzene rings and two isocyanate groups in one molecule, benzene rings and isocyanate groups in one molecule, and NCO content of 5 to 32% in terms of solid content Crude polyisocyanate containing 80-30% by mass of diphenylmethane diisocyanate polynuclear condensate in the range of%, iron content exceeding 60 ppm and acidity exceeding 200 ppm ,
(B) Adsorbing a suspended iron element and a chlorine compound dissolved in the polyisocyanate with activated carbon or diatomaceous earth having a pH of 7.5 to 11.5 and an average particle diameter of 10 to 200 μm,
(C) A method for purifying a polyisocyanate composition can be provided, wherein the iron content is 60 ppm or less and the acidity is 200 ppm or less .

Moreover, according to the present invention,
(A) 20 to 70% by mass of diphenylmethane diisocyanate each having two benzene rings and two isocyanate groups in one molecule, benzene rings and isocyanate groups in one molecule, and NCO content of 5 to 32% in terms of solid content % Diphenylmethane diisocyanate polynuclear condensate in an amount of 80% to 30% by mass, an iron content exceeding 60 ppm, and an isocyanate group-terminated urethane prepolymer obtained by reacting a crude polyisocyanate with an acidity exceeding 200 ppm and a polyol. Polymer,
(B) Adsorbing a suspended iron element and a chlorine compound dissolved in the polyisocyanate with activated carbon or diatomaceous earth having a pH of 7.5 to 11.5 and an average particle diameter of 10 to 200 μm,
(C) A method for purifying a polyisocyanate composition can be provided, wherein the iron content is 60 ppm or less and the acidity is 200 ppm or less.

  The present invention further provides an adhesive composition containing any one of the above organic polyisocyanate compositions.

  The present invention further provides a coating composition containing any of the organic polyisocyanate compositions described above.

  According to the purification method of the present invention, in an organic polyisocyanate composition and an NCO group-terminated urethane prepolymer obtained therefrom, the content and acidity of iron elements that cause an increase in viscosity over time and an increase in coloration are effectively reduced. It can be made.

  Hereinafter, the purification method of the organic polyisocyanate composition of the present invention, the organic polyisocyanate composition, and the adhesive composition and coating composition using the organic polyisocyanate composition will be described.

  The organic polyisocyanate composition obtained by the purification method of the present invention has an iron element content of 60 ppm or less, more preferably 50 ppm or less, and an acidity of 200 ppm or less, more preferably 150 ppm or less. When the content of the iron element is higher than 60 ppm, the viscosity increases due to reaction between isocyanate groups or reaction with slight active hydrogen group-containing compounds in the system such as moisture due to coloring or catalytic effect, and storage stability is poor. Become. On the other hand, when the acidity is higher than 200 ppm, increase in coloration and corrosion of production equipment / filled containers are likely to occur.

  Here, “the content of iron element” is obtained based on the measured value by an atomic absorption photometer. “Acidity” is liberated by reacting with alcohol as defined in ISO-14898 (1998), Plastics-Aromatic isocyanates for use in the production of polyurethane-Determination of acidity (TC 61 / SC 12). The acid component is titrated with alkali and expressed in terms of hydrochloric acid.

  Various methods such as filtration, adsorption, distillation, aeration and the like can be cited as methods for reducing the content and acidity of the iron element, but the purification method according to the present invention is a method based on filtration or adsorption. Examples include activated carbon, diatomaceous earth, hollow fiber, metal filter, ion exchange resin, silica gel, and ceramic filter.

  Among them, activated carbon and diatomaceous earth are preferable in the present invention. The moisture content is preferably as low as possible from the viewpoint of treating the organic polyisocyanate composition, preferably 3.0% or less, more preferably 0.1% or less.

  The iron element content is suspended and dissolved in the organic polyisocyanate composition due to corrosion and / or erosion of the production equipment as described above, while the chlorine compound, which is a substance that expresses as acidity, also dissolves. In order to reduce both of them, the average particle diameter of the filter medium and the adsorbent is preferably 10 to 200 μm, more preferably 10 to 180 μm, and still more preferably 20 to 150 μm. This average particle diameter is a value measured by a laser method. When the average particle diameter is smaller than 10 μm, the filter medium or the adsorbent is clogged and the processing efficiency is lowered. On the other hand, if the average particle size is larger than 200 μm, the specific surface area of the filter medium or adsorbent becomes small, so it is difficult to reduce the content of iron element and the chlorine compound.

  For reducing the acidity of the organic polyisocyanate composition, in general, optimization of phosgenation conditions, distillation purification, inert gas aeration, and the like are efficient. In the adsorption operation, the acidity can be reduced simultaneously with the reduction of the iron element content as described above. That is, regarding the reduction of acidity, the use of a basic filter material or adsorbent makes it possible to effectively reduce chlorine compounds that cause acidity components by utilizing an acid-base reaction.

  The pH of the filter medium or adsorbent in the present invention is preferably 7.5 to 11.5, more preferably 7.8 to 11.2. If pH is less than 7.5, the efficiency by the acid-base reaction in a contact with a filter medium or an adsorbent will fall.

  As described above, the present invention should be characterized by not only the content of iron element but also the acidity by regulating the average particle size of the filter material and adsorbent to 10 to 200 μm and the pH to 7.5 to 11.5. It can be reduced simultaneously.

As conditions for filtration or adsorption, 1 to 20,000 tons, preferably 10 to 18,000 tons of an organic polyisocyanate composition is treated per 1 m ³ of the filtration material or adsorbent, and the filtration or adsorption temperature is 20 to 150 ° C. More preferably, it is 20-120 degreeC, and the pressure of filtration or adsorption | suction is 0.05-5 MPa, More preferably, it is 0.1-3 MPa.

  The organic polyisocyanate composition used in the present invention is a compound having two or more isocyanate groups in one molecule, such as MDI, TDI, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenyl ether diisocyanate, 3,3'-dimethyldiphenylmethane. -4,4'-diisocyanate, phenylene diisocyanate, aromatic diisocyanate such as naphthalene diisocyanate, and aromatic polyisocyanate such as polymeric MDI, crude TDI, and tetramethylene diisocyanate, HDI, 3-methyl-1,5-pentane diisocyanate , Aliphatic diisocyanates such as lysine diisocyanate, further isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated Siri diisocyanate, hydrogenated diphenylmethane diisocyanate, also alicyclic diisocyanates such as hydrogenated tetramethylxylylene diisocyanate can be used.

  Modified products such as bullets, allophanates, isocyanurates (trimers, trimers), uretdiones (dimers), carbodiimides, uretonimines, oxazolidones, amides, etc., in which some of these isocyanate groups (hereinafter referred to as NCO groups) are modified Those modified with imide or the like can also be used.

  These compounds and modified products can be used alone or as a mixture of two or more.

  Furthermore, NCO group-terminated urethane prepolymers obtained from these organic polyisocyanate compositions and active hydrogen hydroxyl group-containing compounds are also organic polyisocyanate compositions that can be used in the present invention.

  The NCO content of the organic polyisocyanate composition and the NCO group-terminated urethane prepolymer of the present invention is preferably 5 to 32% by mass, more preferably 8 to 32% by mass, and 9 to 32% by mass in terms of solid content of 100% by mass. Most preferred. If the isocyanate content is too low or too high, the adhesive strength and adhesion are insufficient.

  When obtaining an NCO group-terminated urethane prepolymer, an active hydrogen group-containing compound having a number average molecular weight of 30 to 10,000 is preferable. If the number average molecular weight is less than 30, the urethane group concentration increases, and metal, wood, paper Adhesive strength with cellulosic aggregates such as plastic, crushed stone, sand, rubber chips, wood chips, rice husks, etc. is manifested, but the viscosity of the NCO group-terminated urethane prepolymer becomes high and the mixing properties at the time of work deteriorate.

  On the other hand, if the number average molecular weight is greater than 10,000, the urethane group concentration is low, which is not preferable because of insufficient adhesive strength and durability with the adherend. The number of functional groups is preferably 1 to 5. At that time, the compounding ratio of the organic polyisocyanate composition and the active hydrogen group-containing compound is equivalent to the NCO group of the organic polyisocyanate composition / hydroxyl group of the active hydrogen group-containing compound = 1.5 to 100. It is necessary to react.

  As the active hydrogen group-containing compound, specifically, methanol, ethanol, propanol, butanol, octanol, lauryl alcohol and other monools, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, Diols such as 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, polyols such as glycerin, trimethylolpropane, pentaerythritol, and other monoethanolamine, diethanolamine, triethanolamine, ethylene glycol mono Start these compounds as well as single or mixture of butyl ether, diethylene glycol monobutyl ether, diglycerin, sorbitol, sucrose, etc. Polyether mono or polyol obtained by addition polymerization of monomers such as ethylene oxide, propylene oxide, glycidyl ether, methyl glycidyl ether or two or more of them by a known method, amine mono or polyol, amino Dehydration of alcohol mono or polyol, polyoxyethylene monoalkyl ethers blocked at one end with an alkyl group, dibasic acids such as adipic acid and phthalic anhydride, and glycols and triols such as ethylene glycol, diethylene glycol and trimethylolpropane Various polyester polyols obtained by condensation reaction, lactone-type polyol obtained by ring-opening polymerization of ε-caprolactam, polycarbonate-type di- or polyol, acrylic polyol, polybutadiene Type polyols, phenolic polyols such as novolak resins and resol resins, and types obtained by radical polymerization of vinyl monomers such as acrylonitrile and styrene in polyols, polymer polyols obtained by dispersing and dissolving these polymers in polyols, tetrahydrofuran The polytetramethylene-type polyol obtained by cationic polymerization of these can be mentioned, It can use individually or in mixture of 2 or more types.

  When using an MDI organic polyisocyanate composition (ie, MDI or polymeric MDI) in terms of cost, workability, toxicity, strength, etc., the above-mentioned aliphatic diisocyanate and alicyclic diisocyanate are also used together if the amount is small The NCO content is preferably 5 to 32% by mass in terms of a solid content of 100% by mass (as a form not including various additives such as the above-mentioned catalyst, surfactant, diluent, plasticizer, flame retardant). 8 to 32 mass% is more preferable, and 9 to 32 mass% is most preferable.

  When using an MDI organic polyisocyanate composition, diphenylmethane diisocyanate (A1) having two benzene rings and two isocyanate groups in one molecule, and diphenylmethane having three or more benzene rings and isocyanate groups in one molecule, respectively. Mass composition ratio with a diisocyanate type polynuclear condensate (A2) is (A1) :( A2) = 20-70: 80-30.

  When there is too little MDI, the viscosity of an MDI type organic polyisocyanate composition tends to become high. Moreover, when there is too much MDI, at the time of the low temperature storage of an MDI type organic polyisocyanate composition, a precipitate will occur easily by crystallization of MDI.

  There are three isomers of MDI in the MDI-based organic polyisocyanate composition of the present invention: 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI. MDI and polymeric MDI can contain not only 4,4'-MDI but also 2,2'-MDI and / or 2,4'-MDI. By including 2,2′-MDI and / or 2,4′-MDI, it is possible to achieve improvement in low-temperature storage stability and further reduction in viscosity.

  The solid content of the organic polyisocyanate composition and the NCO group-terminated urethane prepolymer of the present invention is preferably 10% by mass or more, particularly preferably 20% by mass or more.

  The organic solvent used in this case is preferably a solvent inert to the isocyanate group, which is commonly used in the polyurethane industry. For example, aromatic solvents such as toluene and xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. Ketone solvents, ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate, etc. And glycol ether ester solvents, and ether solvents such as tetrahydrofuran and dioxane. These can be used alone or in combination. These solvents can also be used to increase the effect of filtration or adsorption.

  The adhesive composition and coating composition of the present invention are characterized by using the above-mentioned organic polyisocyanate composition as a curing agent. For example, the adhesive composition and the coating composition are roughly classified into a one-component type and a two-component type. The one-pack type is a type in which the isocyanate group in the organic polyisocyanate composition is further blocked with a blocking agent as a latent curing agent, and is pre-blended with a polyhydric hydroxyl compound as a main component, and is used alone for moisture curing. There is a type to let you. In the two-pack type, this organic polyisocyanate composition is used as a curing agent and a polyhydric hydroxyl compound as a main component is blended and used immediately before use.

  The polyvalent hydroxyl compound containing an active hydrogen group used as the main agent is preferably not only the above-mentioned active hydrogen group-containing compound but also a compound having a number average molecular weight of 500 to 100,000 having two or more hydroxyl groups in the molecule. Specifically, saturated or unsaturated polyester polyol, polycaprolactone polyol, saturated or unsaturated oil-modified or fatty acid-modified alkyd polyol, amino alkyd polyol, polycarbonate polyol, acrylic polyol, polyether polyol, epoxy polyol, fluorine-containing polyol, Furthermore, saturated or unsaturated polyester resin, polycaprolactone resin, saturated or unsaturated oil-modified or fatty acid-modified alkyd resin, amino alkyd resin, polycarbonate resin, acrylic resin, polyether resin, epoxy resin, polyurethane resin, cellulose acetate butyrate Examples thereof include resins and fluorine-containing resins.

  In the adhesive composition and coating composition of the present invention, the equivalent ratio of the (latent) isocyanate group in the organic polyisocyanate composition to the hydroxyl group in the polyvalent hydroxyl compound is 9: 1 to 1: 9, preferably It is in the range of 7: 3 to 3: 7. The composition of the present invention may contain various pigments and various additives commonly used in the lacquer industry in addition to the above-mentioned solvents. Furthermore, the composition of the present invention can be applied by a conventional coating method conventionally used. For coating, an airless spray machine, an air spray machine, an electrostatic coating machine, dipping, a roll coater, a knife coater, a brush. Etc. can be used.

  Furthermore, the organic polyisocyanate composition and the NCO-terminated urethane prepolymer of the present invention, or the adhesive composition and the coating composition may include cement, blast furnace slag, gypsum, calcium carbonate, clay, aluminum hydroxide, Inorganic fillers such as antimony trioxide, quicklime, slaked lime, bentonite, diluents, leveling agents, flame retardants, silicone foam stabilizers, anti-aging agents, heat resistance imparting agents, antioxidants, UV absorbers, catalysts, etc. Can be blended by appropriately adjusting the blending amount.

  Next, the organic polyisocyanate composition of the present invention and the adhesive composition and coating composition using the NCO group-terminated urethane prepolymer obtained therefrom will be described in more detail based on examples. It is not limited to only the examples.

[Synthesis of organic polyisocyanate composition]

[Examples 1-3, Comparative Examples 1-3]
Predetermined amounts of various raw materials other than the organic solvents shown in Tables 1 and 2 were charged into a reactor having a capacity of 2,000 ml equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube. This was heated to 70-80 ° C. with stirring, and the urethanization reaction was advanced until the target NCO content was reached. Thereafter, unreacted TDI in the reaction solution was removed by thin-film distillation at 120 to 140 ° C. and 1 to 5 Pa so that the residual free TDI content was 0.5% by mass or less.

And after adding and diluting an organic solvent, filtration operation was performed using the activated carbon and diatomaceous earth of Table 1, 2, and polyisocyanate solution P-1 to P3 and P-9 to 11 were obtained. In Comparative Example 3 (P-11), since the pH of diatomaceous earth was too high, the isocyanate was gelled and a uniform liquid was not obtained. Tables 1 and 2 show the iron element content (Fe amount), acidity, and various analysis results.
[Example 4, Comparative Example 4]
In the same manner as described above, predetermined amounts of various raw materials shown in Tables 1 and 2 were charged into a reactor having a capacity of 2,000 ml equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube. This was heated to 70-80 ° C. with stirring, and the urethanization reaction was advanced until the target NCO content was reached. Then, unreacted HDI in the reaction solution was removed by thin-film distillation at 120 to 140 ° C. and 1 to 5 Pa so that the residual free HDI content was 0.5% by mass or less.

And filtration operation was performed using the activated carbon of Table 1, 2, and polyisocyanate solution P-4 and P-12 were obtained. Tables 1 and 2 show the iron element content (Fe amount), acidity, and various analysis results.
[Examples 5-7, Comparative Examples 5-7, 9]
In the same manner as described above, predetermined amounts of various raw materials shown in Tables 1 and 2 were charged into a reactor having a capacity of 2,000 ml equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube. This was heated to 70-80 ° C. with stirring, and the urethanization reaction was advanced until the target NCO content was reached.

And filtration operation was performed using the activated carbon and diatomaceous earth of Table 1, 2, and polyisocyanate solution P-5-7 and P-13-15, 17 were obtained. In Comparative Example 6 (P-14), since the pH of the activated carbon was too high, the isocyanate gelled and a uniform liquid was not obtained. Tables 1 and 2 show the iron element content (Fe amount), acidity, and various analysis results.
[Example 8, Comparative Examples 8, 10, 11]
Filtration operation was performed on PMDI-2 of polymeric MDI shown in Tables 1 and 2 using diatomaceous earth shown in Tables 1 and 2 to obtain polyisocyanate solutions P-8 and P-16, 18, and 19. In Comparative Examples 10 and 11 (P-18 and 19), since the pH of diatomaceous earth was too high, the isocyanate gelled and a uniform liquid was not obtained. Tables 1 and 2 show the iron element content (Fe amount), acidity, and various analysis results.
[Measurement of iron element content (Fe content) and acidity]
The content of iron element (Fe content) is measured with an atomic absorption photometer, and the acidity is obtained by titrating with acid an acid component that is liberated by reacting with alcohol as defined in ISO 14898 (1998). Indicated.
[Conditions for filtration operation]
The filtration operation was performed at a pressure of 0.3 MPa and a temperature of 50 ± 3 ° C. using activated carbon or diatomaceous earth having a capacity of 10 cm ³ .

[Isocyanate group-containing raw material]
TDI-1: Tolylene diisocyanate (2,4-TDI only)
Iron element content (Fe content) = 130ppm
Acidity = 210ppm
NCO content = 48.3%
TDI-2: Tolylene diisocyanate isomer mixture
2,4-TDI / 2,6-TDI = 80/20 (mass
ratio)
Iron element content (Fe content) = 120ppm
Acidity = 290ppm
NCO content = 48.3%
TDI-3: Tolylene diisocyanate isomer mixture
2,4-TDI / 2,6-TDI = 65/35 (mass
ratio)
Iron element content (Fe content) = 120ppm
Acidity = 220ppm
NCO content = 48.3%
HDI: Hexamethylene diisocyanate
Iron element content (Fe content) = 210 ppm
Acidity = 400ppm
NCO content = 50.0%
MDI-1: Diphenylmethane diisocyanate
Total content of 2,2'-MDI and 2,4'-MDI
= 0.1%
Iron element content (Fe content) = 80ppm
Acidity = 210ppm
NCO content = 33.6%
MDI-2: Diphenylmethane diisocyanate
Total content of 2,2'-MDI and 2,4'-MDI
= 28%
Iron element content (Fe content) = 90ppm
Acidity = 220ppm
NCO content = 33.6%
PMDI-1: Polymeric MDI
MDI content in polymeric MDI = 42%
2,2'-MDI and 2,4'-MDI in MDI components
Total content = 0.1%
Iron element content (Fe content) = 140 ppm
Acidity = 380ppm
NCO content = 31.1%
PMDI-2: Polymeric MDI
MDI content in polymeric MDI = 36%
2,2'-MDI and 2,4'-MDI in MDI components
Total content = 17%
Iron element content (Fe content) = 130ppm
Acidity = 620ppm
NCO content = 31.3%
[Active hydrogen-containing raw materials]
TMP: trimethylolpropane, functional group number = 3
Glycerin: Glycerin, number of functional groups = 3
1,3-BD: 1,3-butanediol, functional group number = 2
PG: propylene glycol, functional group number = 2
PP-1000: poly (oxypropylene) polyol
Number average molecular weight = 1,000
Average number of functional groups = 2
Oxypropylene group content = 100%
PP-2000: Poly (oxypropylene) polyol
Number average molecular weight = 2,000
Average number of functional groups = 2
Oxypropylene group content = 100%
MPEG-700: Mono (oxyethylene) polyol
Number average molecular weight = 700
Number of functional groups = 1
Oxyethylene group content = 100%

[Storage stability test method]
(1) Viscosity The viscosity immediately after the synthesis of each polyisocyanate solution (measured value at 25 ° C.) was compared with the viscosity after standing at 50 ° C. for 30 days (measured value at 25 ° C.). .
(2) Coloring For each polyisocyanate solution, the coloration immediately after the synthesis was compared with the coloration after standing at 50 ° C. for 30 days. Coloring was performed according to the number of Hazen units by a method based on JIS K0071-1. The MDI-based organic polyisocyanate composition was colored by a 200-fold (mass / mass) dilution with acetone according to the number of Hazen units.

[Compatibility test with other resins]
Examples 9-13, Comparative Examples 12-16
Immediately synthesized products of the polyisocyanate solutions P-2, 4, 6-8, 10, 12, 15-17 obtained in Examples 2, 4, 6-8 and Comparative Examples 2, 4, 7-9, For each of the untreated items at 50 ° C. for 30 days, it was mixed with various resins described in Table 3 and Table 4 at a mass ratio of 1/1, and the obtained mixed solution was applied to a glass plate. The appearance of the coating film after the solvent was completely dispersed at 120 ° C. for 1 hour was judged according to the following evaluation criteria.
○: Transparent, △: Slightly cloudy, ×: Opaque

  From Tables 1 to 4, the polyisocyanate solution having an iron content of 60 ppm or less and an acidity of 200 ppm or less shows a result of good compatibility with other resins because the degree of coloring is low over time and the viscosity increase is also low. It was. Comparative Examples 12 and 15 had good compatibility with other resins, but as shown in Table 2, the degree of coloring over time was large.

[Adhesive evaluation]
Examples 14-18, Comparative Examples 17-21
Each polyisocyanate solution P-2, 4, 6-8, 10, 12, 15-17 obtained in Examples 2, 4, 6-8 and Comparative Examples 2, 4, 7-9 was used as a curing agent. Evaluation of the two-component type adhesive was performed on each of the product immediately after the synthesis of the polyisocyanate solution and the product left under the condition of 30 days at 50 ° C. NIPPOLAN 3016 (ethyl acetate solution, hydroxyl group content = 0.04 mmol / g, manufactured by Nippon Polyurethane Industry, solid content = 22%), which is a polyurethane resin solution for adhesives, was used as the main agent. The mixing ratio of the main agent and the curing agent was such that the hydroxyl group in the main agent and the isocyanate group in the curing agent were equivalent.

  Length 100mm, width 25mm, thickness 1mm polyurethane RIM (reactive injection molding) molded product, FRP, ABS, steel plate (JIS G3141 <3141-SB>, specifications: PF-1077, manufactured by Nippon Test Panel Industry, the following: Bonded steel sheet) was degreased with trichlorethylene, and an adhesive containing the above main agent / curing agent was applied thereon so that the dry film thickness was 40 to 50 μm and the application area was 25 mm × 25 mm. Then, it is pre-dried at 50 ° C. for 5 minutes to evaporate the solvent in the adhesive, and the above-mentioned plates of the same type are stacked so as not to contain air bubbles, and pressure-bonded at 2.5 MPa. And left in a 65% RH atmosphere for 1 week to obtain an adhesive sample. Thereafter, the adhesive shear strength was measured under the conditions of tensile rate = 100 mm / min and measurement atmosphere = 23 ° C. × 50% RH. The results are shown in Tables 5 and 6.

  As shown in Tables 5 and 6, the adhesive using the organic polyisocyanate solution of the present invention as a curing agent showed no significant difference in the adhesive strength between the examples and the comparative examples in the comparison immediately after synthesis. As a result after 30 days at 50 ° C., Comparative Examples 18, 19, and 21 showed lower adhesive strength than the Examples, and Comparative Examples 17 and 20 showed adhesive strengths almost the same as those of the Examples except for the bonded steel plates. . In the case of the bonded steel plate, rust was observed in all the comparative examples as a result of 30 days after 50 ° C.

[Paint evaluation]
Examples 19 to 23, Comparative Examples 22 to 26
Each polyisocyanate solution P-2, 4, 6-8, 10, 12, 15-17 obtained in Examples 2, 4, 6-8 and Comparative Examples 2, 4, 7-9 was used as a curing agent. A paint was prepared by blending and kneading each paint raw material with the blends shown in Tables 7 to 10 for each of the product immediately after the synthesis of the polyisocyanate solution and the product left to stand at 50 ° C. for 30 days. The blended paint was applied to a bonded steel plate previously degreased with trichlorethylene and allowed to stand for 1 week in an environment of 20 ° C. × 65% RH to form a coating film having a dry film thickness of 40 to 50 μm. And the physical property of the formed coating film was measured according to prescription of JIS K5400. The results are shown in Tables 7-10.

In Tables 7-10, Hitaroid 3088: Acrylic polyol
Made by Hitachi Chemical
Hydroxyl value = 50 mgKOH / g
Solid content = 50%
Nippon Runan 800: Polyester polyol
Made by Nippon Polyurethane Industry
Hydroxyl value = 290 mgKOH / g
Solid content = 100%
Nippon Run 1100: Polyester polyol
Made by Nippon Polyurethane Industry
Hydroxyl value = 213 mgKOH / g
Solid content = 100%
In the description of the above-mentioned compounds, “Hitaroid” is a registered trademark of Hitachi Chemical Co., Ltd., and “Nipporan” is a registered trademark of Nippon Polyurethane Industry Co., Ltd.

  As shown in Tables 7 to 10, the paint using the polyisocyanate composition of the present invention as a curing agent has a low gloss increase over time of the organic polyisocyanate composition, and therefore better gloss and adhesion than the comparative examples. Retained sex. Furthermore, in the comparative example, generation | occurrence | production of the rust of the bonde steel plate was seen.

  The organic polyisocyanate composition obtained by the purification method of the present invention and the NCO group-terminated urethane prepolymer obtained therefrom have little change in viscosity and increase in color over time, so that the storage stability is improved, and further with other resins. Therefore, an adhesive and a paint excellent in adhesive strength, adhesion, appearance and the like can be obtained.

Claims (6)

(A) 20 to 70% by mass of diphenylmethane diisocyanate each having two benzene rings and two isocyanate groups in one molecule, and
(B) One molecule contains a benzene ring and an isocyanate group , the NCO content is in the range of 5 to 32% by mass in terms of solid content, and the diphenylmethane diisocyanate polynuclear condensate is contained in 80 to 30% by mass , and the iron content A crude polyisocyanate having an acidity of more than 60 ppm and an acidity of more than 200 ppm,
(C) The activated iron or diatomaceous earth having a pH of 7.5 to 11.5 and an average particle size of 10 to 200 μm is adsorbed with a suspended iron element and a chlorine compound dissolved in the polyisocyanate, and contains iron. 60 ppm or less, acidity was 200 ppm or less ,
Polyisocyanate composition. (A) 20 to 70% by mass of diphenylmethane diisocyanate each having two benzene rings and two isocyanate groups in one molecule, and
(B) One molecule contains a benzene ring and an isocyanate group , the NCO content is in the range of 5 to 32% by mass in terms of solid content, 80 to 30% by mass of diphenylmethane diisocyanate polynuclear condensate, and the iron content is An isocyanate group-terminated urethane prepolymer obtained by reacting a crude polyisocyanate with a acidity exceeding 60 ppm and an acidity exceeding 200 ppm with a polyol selected from polypropylene glycol or polyethylene glycol methyl ether ,
(C) The activated iron or diatomaceous earth having a pH of 7.5 to 11.5 and an average particle size of 10 to 200 μm is adsorbed with a suspended iron element and a chlorine compound dissolved in the polyisocyanate, and contains iron. Is a polyisocyanate composition having an acidity of 200 ppm or less. (A) 20 to 70% by mass of diphenylmethane diisocyanate each having two benzene rings and two isocyanate groups in one molecule, benzene rings and isocyanate groups in one molecule, and NCO content of 5 to 32% in terms of solid content Crude polyisocyanate containing 80-30% by mass of diphenylmethane diisocyanate polynuclear condensate in the range of %, iron content exceeding 60 ppm and acidity exceeding 200 ppm,
(B) Adsorbing a suspended iron element and a chlorine compound dissolved in the polyisocyanate with activated carbon or diatomaceous earth having a pH of 7.5 to 11.5 and an average particle diameter of 10 to 200 μm,
(C) 60 ppm or less content of iron, characterized in that the acidity and 200ppm or less, the purification method of the polyisocyanate composition. (A) 20 to 70% by mass of diphenylmethane diisocyanate each having two benzene rings and two isocyanate groups in one molecule, benzene rings and isocyanate groups in one molecule, and NCO content of 5 to 32% in terms of solid content % Diphenylmethane diisocyanate polynuclear condensate in an amount of 80% to 30% by mass, an iron content exceeding 60 ppm, and an isocyanate group-terminated urethane prepolymer obtained by reacting a crude polyisocyanate with an acidity exceeding 200 ppm and a polyol. Polymer,
(B) Adsorbing a suspended iron element and a chlorine compound dissolved in the polyisocyanate with activated carbon or diatomaceous earth having a pH of 7.5 to 11.5 and an average particle diameter of 10 to 200 μm,
(C) 60 ppm or less content of iron, characterized in that the acidity and 200ppm or less, the purification method of the polyisocyanate composition. The adhesive composition containing a polyisocyanate group composition as claimed in claim 1 or claim 2. Coating compositions containing the polyisocyanates set composition as claimed in claim 1 or claim 2.