JP2007169432A - Solventless polyurethane composition and its cured product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyurethane composition which has good storage stability and good adhesion, gives a cured product having good external appearance with reduced foaming without surface tack, and has no problem of environmental hygiene. <P>SOLUTION: The solventless polyurethane composition comprises a urethane prepolymer having an isocyanate group and a curing catalyst, and contains not less than 3 mass% isocyanate groups, and the curing catalyst comprises at least one kind of an iron organic carboxylate and iron acetylacetonate which is dissolved in a solvent having a boiling point of not lower than 150°C, and the composition contains not more than 1 mass% solvent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solvent-free polyurethane composition having an isocyanate group, and more particularly to a solvent-free polyurethane composition having an isocyanate group containing a low-toxic curing catalyst.

  In recent years, in the field of adhesives and the like, so-called solventless polyurethane compositions containing no solvent have attracted attention and are widely used as adhesives, sealing agents, flooring agents, waterproofing coatings, casting materials, and the like. In general, it is formulated as a one-component or two-component liquid composition, and is applied in the form of a thin film containing a reactive isocyanate group at the start of use, and the isocyanate group is reacted with an active hydrogen compound and cured. It is designed to exhibit various physical properties such as adhesiveness, sealability, rubber elasticity, and waterproofness.

  In the case of a prescription used in a one-pack type, it contains a prepolymer having an isocyanate group, an isocyanate monomer, a curing catalyst, and other additives, and is taken out from a storage container. It reacts with water in the air and hardens. In the case of a two-part formulation, the first liquid contains an active hydrogen compound such as polyol and / or polyamine, a curing catalyst, and other additives, and the second liquid consists of a prepolymer having an isocyanate group. The reaction starts immediately after the two liquids are mixed and applied in the form of a thin film, and finally cured.

Conventionally, organotin compounds, lead carboxylates, and bismuth carboxylates are well known as urethane curing catalysts. However, the use of these organometallic compounds has been a problem from the viewpoint of environment, health and safety, and alternative catalysts not containing harmful metal compounds have been studied.
Among them, organic iron compounds have been studied from the advantages such as little influence on the environment, relatively high catalytic activity, long pot life, low foaming and high adhesive strength. For example, a combination of ferric acetylacetonate and a copper compound or a tin compound has long been known (for example, see Patent Document 1).

  In addition, it has been proposed to produce a rotational molded body by heating using a urethane-based resin material using a mixed catalyst of metal acetylacetonate and acetylacetone (see, for example, Patent Document 2). However, it is a molded article obtained by using an equivalent amount of a polyol which is an active hydrogen compound with respect to an isocyanate group, has no adhesion performance, and has a problem that the pot life of the mixed urethane-based resin raw material liquid is short.

  In addition, a polyurethane composition for a sealing agent having improved catalytic activity using a mixture of bismuth organic carboxylate and another metal salt of organic carboxylate as a curing catalyst has been proposed (for example, see Patent Document 3). Organic bismuth compounds have been pointed out as environmental problems.

In addition, when all conventional iron-based catalysts are used in a solvent-free polyurethane composition, the curing rate is slow when used alone, and therefore the reaction start-up at a relatively low temperature such as room temperature is slow. In addition, there is a problem that tack remains on the surface of the cured product, resulting in insufficient adhesion of dust and adhesive force.Furthermore, foaming increases when the reaction is slow or when the humidity is high, causing a decrease in adhesive force. There was a problem that the strength of the cured product was lowered.
On the other hand, increasing the amount of catalyst added or adding a cocatalyst or activation aid is effective in shortening the curing time, but conversely, the storage stability of the polyurethane composition, the pot life, and the open time are shortened. There are problems such as non-uniform progression of reaction, reduced strength of cured products due to increased foaming, and poor appearance.
U.S. Patent No. 3314834 JP 2004-323680 A JP 2001-89549 A

  The present invention has a good storage stability of the polyurethane composition, has an appropriate pot life and an open time in the bonding process, has a good adhesive force, has less foaming, and has a good appearance with no surface tack. It is an object of the present invention to provide a polyurethane composition and a cured product which give a product and which are free from environmental health problems.

An object of the present invention is an organic iron carboxylate in which a polyurethane composition comprising a urethane prepolymer having an isocyanate group and a curing catalyst contains 3% by mass or more of an isocyanate group and the curing catalyst is dissolved in a solvent having a boiling point of 150 ° C. or higher. And a solvent-free polyurethane composition comprising at least one of iron acetylacetonate and having a solvent content of 1% by mass or less.
Further, in the above solvent-free polyurethane composition, the urethane prepolymer is a reaction product of an aromatic polyisocyanate compound and at least one of a polyoxyalkylene polyol and a polyester polyol.
The solvent-free polyurethane composition containing a polyalkyl vinyl ether compound.
The cured product obtained by curing the polyurethane composition is composed of at least one of organic carboxylate iron and iron acetylacetonate in which the isocyanate group concentration is 3% by mass or more and the curing catalyst is dissolved in a solvent having a boiling point of 150 ° C. or more. A cured product obtained by applying a solvent-free polyurethane composition having a solvent content of 1% by mass or less to an adherend and then curing it by heating to 70 ° C. or higher.

  The polyurethane composition of the present invention uses, as a curing catalyst, at least one of organic carboxylic acid iron and iron acetylacetonate dissolved in a solvent having a boiling point of 150 ° C. or higher, and the solvent is 1% by mass or less. Environmental hygiene that enables polyurethane compositions to have good storage stability, moderate pot life and open time, good adhesion, and good cured products with little foam and no surface tack A polyurethane composition without the above problems can be provided.

The polyurethane composition of the present invention is a solventless polyurethane composition comprising a prepolymer having an isocyanate group and a specific curing catalyst.
In the present invention, the urethane prepolymer having an isocyanate group is used as a curing component, and is reacted with an active hydrogen or a group having active hydrogen from an organic polyisocyanate and an active hydrogen-containing compound under an isocyanate group excess condition. It is obtained. Examples of the isocyanate compound used as the raw material for the urethane prepolymer include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric MDI, modified MDI such as liquid MDI, hydrogenated TDI, hydrogenated MDI, hexamethylene diisocyanate (HDI). ), Xylylene diisocyanate (XDI), naphthalene diisocyanate (NDI), triphenylmethane triisocyanate, isophorone diisocyanate (IPDI), and the like. Of these, aromatic diisocyanates and aliphatic diisocyanates are excellent in adhesiveness after curing. In the present invention, MDIs, TDIs, and polymeric MDI are particularly preferable, and polymeric MDI is more preferable.

As the urethane prepolymer, one synthesized by the reaction of the aforementioned isocyanate and polyol is used.
For example, the above two compounds are blended in such a ratio that the equivalent ratio (NCO / OH) of the isocyanate group (NCO) contained in the isocyanate compound to the hydroxyl group (OH) contained in the polyol is NCO / OH = 1.3-10. In the presence or absence of a catalyst, the reaction is performed at a temperature of 50 to 120 ° C. for about 3 to 10 hours.
As the polyol, those having two or more active hydrogen groups and capable of producing a terminal isocyanate group-type polyurethane prepolymer by reacting with an isocyanate compound can be used. 000 and an average functional group number (the number of active hydrogen groups) of 2 to 4.

For example, low molecular weight divalent or trihydric alcohols, polyether polyols, polyester polyols, polycarbonate polyols, polycaptolactone polyols, animal and plant polyols, polyacryl polyols, polyolefin polyols, amino alcohols, Polyamines can be used. These can be used alone or in combination of two or more.
Among these, by using at least one of polyoxyalkylene polyether and polyester polyol, it is possible to obtain a product having excellent adhesion and low workability.
The average molecular weight of the polyoxyalkylene polyols and polyester polyols is preferably about 300 to 8,000, particularly about 400 to 6,000, exhibiting a low viscosity liquid at normal temperature. These molecular weights are advantageous from the viewpoints of workability and physical properties when applied to and mixed with an adherend.

  Examples of the polyoxyalkylene polyol include polyoxyethylene polyol, polyoxypropylene polyol, polyoxybutylene polyol, polytetramethylene ether polyol, (polyoxyethylene)-(polyoxypropylene) random or block copolymer polyol, (poly And oxypropylene)-(polyoxybutylene) random or block copolymer polyol.

  Examples of the polyester polyol include succinic acid, adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, orthophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, hexahydroorthophthalic acid, naphthalenedicarboxylic acid, triphthalic acid, and the like. One or more of polycarboxylic acids such as merit acid, acid esters, or acid anhydrides, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9- Nonanediol, diethylene glycol, dipropylene glycol, , 4-cyclohexanedimethanol, ethylene oxide or propylene oxide adduct of bisphenol A, low molecular alcohols such as trimethylolpropane, glycerin and pentaerythritol, low molecular amines such as hexamethylenediamine, xylylenediamine and isophoronediamine Polyester polyols or polyester amide polyols obtained by a dehydration condensation reaction with one or more low molecular amino alcohols such as monoethanolamine and diethanolamine.

  Chain extenders can also be used as the active hydrogen-containing compound. Preferred examples of the chain extender include low molecular weight alcohols such as ethylene glycol, low molecular weight amines such as ethylene diamine, low molecular weight amino alcohols and the like having a molecular weight of less than 500, or a mixture of two or more thereof. The

The polyurethane composition in the present invention may contain an isocyanate compound that is a raw material for the urethane prepolymer. In particular, polymeric MDI is preferable from the viewpoint of safety that it is liquid and easy to handle and has a low vapor pressure.
In the present invention, the content of the isocyanate group in the polyurethane composition is usually about 3 to 20% by mass in the liquid at the time of coating use, whether it is one liquid or two liquids, and 5 to 15 weights. % Is preferably used. Especially preferably, it is 6-12 mass%.
When the isocyanate group content is less than 3% by mass, the molecular weight becomes too large, the viscosity increases, and the workability decreases. Moreover, not only does not contribute to the improvement of the activity of the curing catalyst, but also there are few crosslinking points in the prepolymer, so that sufficient adhesion cannot be obtained. When the isocyanate group content exceeds 20.0% by mass, foaming due to carbon dioxide gas becomes severe, which is not preferable.
Moreover, it is preferable that the liquid viscosity of a polyurethane composition is 500-20,000 mPa * s (25 degreeC), and if a viscosity is 500 mPa * s or less, a polyurethane composition cannot be hold | maintained uniformly on a to-be-adhered body surface. Moreover, workability is inferior at 20,000 mPa · s or more.

Examples of the curing catalyst to be blended in the polyurethane composition of the present invention include at least one of organic carboxylic acid iron and iron acetylacetonate dissolved in a solvent having a boiling point of 150 ° C. or higher.
The iron compound may be in any form of ferrous or ferric, and may be used alone or as a mixture. Examples of the organic carboxylic acid include octylic acid, neodecanoic acid, naphthenic acid, acetic acid, propionic acid, oleic acid, stearic acid and the like. Naphthenic acid and octylic acid are preferred because they have good compatibility with polyisocyanates.

  In the present invention, it is necessary that these catalysts are dissolved in a solvent and blended in the composition and sufficiently dissolved. If the dissolved state is insufficient, the curing reactivity as a catalyst is poor. For this purpose, the catalyst is dissolved in a solvent by heating to obtain a solution. The solution concentration of the catalyst is 3% by mass or more as iron, and the organic iron compound can be measured as a nonvolatile content, and the solution concentration is 20% by mass or more. If it is lower than this, when it is blended in the polyurethane composition, the amount of volatile components increases, making it difficult to say that it is a solventless type.

  In the present invention, a solvent having a boiling point of 150 ° C. or higher is used as the catalyst solvent. When the boiling point is less than 150 ° C., the volatility is high, and not only the handling and storage properties are problematic, but also a flammability problem occurs. Examples of such solvents include petroleum monobasic acid esters such as octyl propionate, lauryl octylate, hexyl oleate, glycerin monooleate, isoparaffins, olefins, naphthenes, and aromatic hydrocarbons. Mineral solvents, naphthenic acid, lauric acid, neodecanoic acid, octylic acid, oleic acid, linoleic acid and other monocarboxylic acids, phthalic acid esters such as dioctyl phthalate and dicyclohexyl phthalate, dibutyl adipate, adipine Dioctyl acid, dioctyl sebacate, dioctyl maleate, dimethyl malonate, aliphatic dibasic acid esters such as diethyl malonate, phosphoric acid esters such as tributyl phosphate, trioctyl phosphate, tricresyl phosphate, diethylene glycol dia Pies, dihydric alcohol esters such as triethylene glycol 2-ethyl butyrate, oxyacid esters such as acetyl triethyl citrate and the like. Particularly preferred are mineral spirits, phthalic acid esters, adipic acid esters, octylic acid and the like.

  The curing catalyst is preferably blended in an amount of 0.005 to 2 parts by weight, particularly 0.05 to 0.5 parts by weight as iron with respect to 100 parts by weight of the urethane prepolymer having an isocyanate group.

  When the polyurethane composition according to the present invention reacts with moisture or active hydrogen on the surface of the adherend and cures, a curing promoting co-catalyst can be further added to promote the effect. Examples of the curing acceleration co-catalyst that can be used include metal alkoxides such as tetra-n-butyl titanate and sodium methylate, metals such as zinc, zirconium, cobalt and nickel, and octylic acid, octenoic acid and naphthenic acid. Organic acid salts, organic chelate compounds such as acetylacetonate, triethylenediamine, tri-n-butylamine, tetramethyl-1,2-ethylenediamine, and organic acids of 1,8-diazabicyclo (5,4,0) -undecene-7 Examples thereof include organic amines such as salts, and these can be used alone or in combination of two or more. Of these, amine compounds are preferred because of their high effect of promoting curing.

  In the solution in which the curing catalyst is dissolved, carboxylic acid or acetylacetone is used as a catalyst stabilizer. Specific examples include aromatic carboxylic acids such as benzoic acid, phthalic acid, and toluenesulfonic acid, and aliphatic carboxylic acids such as 2-ethylhexyl acid, octylic acid, stearic acid, oleic acid, linoleic acid, montanic acid, and oxalic acid. Naphthenic acid such as 2-methylcyclopentane-1-carboxylic acid.

The polyurethane of the present invention is a solvent-free polyurethane composition. The solvent is introduced as a solvent for the curing catalyst or the like. However, if the organic solvent having a boiling point of 150 ° C. or higher is 1% by mass or less, it is effective as a measure against VOC.
Generally, an organic compound having a boiling point of 260 ° C. or lower is included as a solvent in VOC countermeasures. For example, a boiling point of 150 ° C. or higher in an organic liquid of 300 ° C. or higher such as MDI, polypropylene glycol, or polyester diol as a urethane prepolymer raw material. When the content of the organic solvent is 1% by mass or less, the boiling point of the mixed liquid is 260 ° C. or more, which is effective as a measure against VOC.

In the present invention, an antifoaming agent may be used for the purpose of suppressing foaming during the curing process. Examples of antifoaming agents include higher alcohols, nonionic soaps, and silicone oils. Among these, polyalkyl vinyl ether is preferable from the viewpoint of not inhibiting the adhesiveness. It is 0.01-0.5 weight part with respect to 100 weight part of polyurethane compositions. If the amount added is small, the effect of suppressing the generation of bubbles is small, and on the other hand, increasing the amount added is not preferable from an economical viewpoint.
The present antifoaming agent is particularly effective when the foamed product is often foamed when the polyurethane composition of the present invention is reacted / cured under mild reaction conditions such as room temperature or under humid conditions.

Further, the polyurethane composition of the present invention further includes a filler, a colorant, a diluent, a plasticizer, a storage stabilizer, a weathering stabilizer, an adhesion promoter, a thixotropic agent, a slip agent, a leveling agent, an increase agent. A sticking agent, a dispersing agent, a color separation preventing agent, an anti-settling agent, a stabilizer, and the like can be added.
As the filler, various artificial or natural fillers such as calcium carbonate, barium carbonate, barium sulfate, talc, anhydrous gypsum, magnesium carbonate, mica, zinc white, kaolin, zeolite, and diatomaceous earth can be used.

As the colorant, a part of the filler can be used as an extender, and titanium oxide, iron oxide, bengara, carbon black, iron black, an insoluble azo pigment, a phthalocyanine pigment, and the like are used.
As diluents, alkylbenzene, liquid paraffin, mineral spirits, high boiling point solvents such as solvents having a boiling point of 150 ° C. or higher can be used. When these are used, the total amount with the solvent used as the solvent for the curing catalyst Must be 1% by mass or less.

The storage stabilizer is used to increase the storage stability of the polyurethane composition. Specifically, for example, a phosphate ester compound such as 2-ethylhexyl acid phosphate, octagudecyl isocyanate, and the like. And organic monoisocyanates. The addition amount of the storage stabilizer is 0 to 2 parts by weight with respect to 100 parts by weight of the polyurethane composition.
The weather resistance stabilizer is used to prevent oxidation, light deterioration, and heat deterioration of the cured product and further improve not only the weather resistance but also the heat resistance. Specific examples of the weathering stabilizer include hindered amine-based and hindered phenol-based antioxidants, ultraviolet absorbers, and photocurable compounds.

The adhesiveness imparting agent is used for improving the adhesiveness after curing of the curable composition. For example, a coupling agent, an epoxy resin, a phenol resin, and an organic polyisocyanate similar to the above organic polyisocyanate. Etc.
Examples of the coupling agent include various coupling agents such as silane, aluminum, zircoaluminate, and titanium, and partial hydrolysis condensates thereof. Of these, the silane coupling agent and its partially hydrolyzed condensate have a high adhesion-imparting effect.

  The polyurethane composition of the present invention can be used as a one-pack type or a two-pack type depending on the application, but there is no need to mix the non-isocyanate component liquid and the isocyanate component liquid, and curing failure due to poor mixing, etc. Therefore, a one-component curable composition is preferable.

  In the case of using a two-component solution to improve the stability of storage liquids under harsh conditions and the physical properties of cured products, non-isocyanate component solutions may contain oligomers with active hydrogen, chain extenders, and fillers as necessary. You may mix | blend additives, such as an agent, anti-aging agent, a ultraviolet absorber, a light stabilizer, antioxidant, a pigment or a dye coloring agent, a dispersing agent, a plasticizer.

The polyurethane composition of the present invention is used for adhesives for construction or civil engineering, automobiles, paints, sealing materials, flooring agents, waterproofing coatings, casting materials and the like. Specifically, a rubber chip or sand and a polyurethane composition are mixed to obtain a mat-like cured product in a mold or on a molded plate.
Moreover, you may form an elastic sheet on the floor which consists of inorganic materials, such as mortar and concrete, natural stone materials, such as a marble, and ceramic materials, such as a siding and a tile, with the mixture of these rubber chips and a polyurethane composition. Alternatively, the rubber chip mat may be applied as a polyurethane composition as a primer for improving the adhesion between the floor surface and the sheet when directly forming the elastic sheet on the floor.

  It is also used as a polyurethane composition for sealing between glass and metal. In addition, various synthetic resins such as polyethylene, polyvinyl chloride, ABS resin, polyester, and expanded polystyrene sheets, plates, rain gutters, woody materials such as wood and plywood, metals such as steel plates and aluminum plates It is used as an adhesive between various materials such as system materials.

In the case of obtaining a cured product by molding a mixture of the adherend and the polyurethane composition of the present invention with a mold, in the curing process in order to increase production speed and suppress foaming to obtain a good appearance and adhesive strength. It is preferable to heat the temperature to 70 ° C. or higher, preferably 90 ° C. or higher.
The higher the heating temperature, the faster the reaction rate, but it is preferably 200 ° C. or lower from the viewpoint of preventing ignition and discoloration.
In addition, since the reaction rate is increased by increasing the reaction temperature, foaming can be suppressed and the strength of the cured product can be increased, and a molded product without foaming can be obtained without adding an antifoaming agent.
The heating time is 1 to 60 minutes, preferably 2 to 15 minutes.

  When using on the floor, etc., by applying the polyurethane composition taken out from the storage container with a brush, spatula, roll coater, spray gun, etc. There are various methods, such as a method of attaching to an extrusion gun and extruding and filling manually, electrically or pneumatically, and may be appropriately selected depending on the application.

As a container for storing the polyurethane composition of the present invention, it is necessary to use a container that ensures hermeticity. For example, various containers such as drum cans, metal or synthetic resin pail cans, square cans or bag-like containers, and paper or synthetic resin cartridge-like containers can be used. In particular, the isocyanate component liquid needs to be stored in a state where the polyurethane composition is packed in a container and sealed to block moisture in order to maintain storage stability.
Hereinafter, the present invention will be described with reference to examples and comparative examples.

  A glass reactor equipped with a heating device, a thermometer, a nitrogen seal, a stirrer, and a cooling condenser was charged with 22 parts by weight of polymeric diphenylmethane diisocyanate (BAPL Japan Luplanate M-20S, hereinafter referred to as p-MDI). 56 parts by weight of polypropylene glycol having a molecular weight of 2,000 (Asahi Glass Urethane Excenol 2020, hereinafter also referred to as PPG-1) and 2 parts by weight of polypropylene glycol having a molecular weight of 300 (hereinafter Exaenol 430 by Asahi Glass Urethane, also referred to as PPG-2) 3 parts by weight of a polyester diol having a molecular weight of 2,000 (Kuraray Kuraray Polyol P-2010) synthesized from adipic acid and 3-methyl-1,5-pentanediol is added and mixed. Thereafter, the temperature is heated to 80 ° C., and the reaction is performed for 10 hours, and then the temperature is set to room temperature to obtain a urethane prepolymer liquid having an isocyanate group.

A ferrous naphthenate solution (manufactured by Wako Pure Chemical Industries, Ltd.) containing 5.0% by mass (55% by mass as non-volatile content) of iron dissolved in mineral spirit in advance is 0.8% with respect to 100 parts by weight of the urethane prepolymer solution. The solvent-free polyurethane composition of Sample 1 was obtained by blending parts by weight.
In Table 1, since the urethane prepolymer liquid is 88 parts by weight, the amount of ferrous naphthenate is 0.37 parts by weight.
The content rate of the mineral spirit which is a solvent component is 0.4 mass%. The viscosity of the composition was 4,000 mPa · s (25 ° C.), and the isocyanate group concentration was 4.0% by mass. The composition was sealed in a glass bottle well substituted with nitrogen, and stored.

The obtained polyurethane composition was subjected to an evaluation test by the following evaluation test method, and the results are shown in Table 1. The storage stability of the liquid is excellent, the pot life when blended and molded with rubber chips is 100 minutes, the handling time after mixing is sufficiently secured, and the workability is good.
In addition, after 8 hours at room temperature, there is no tack and curing is fast. No foaming is observed in the cured product. Curing was performed under the curing conditions of 140 ° C. for 10 minutes, and a molded article having high strength was obtained.

(Evaluation test method)
(1) Storage stability of liquid: The appearance and viscosity when a sample stored in a sealed glass bottle was stored at 50 ° C. for 1 week were visually determined according to the following evaluation criteria.
Almost no change ………… Excellent Slightly increased viscosity ………… Good Coloring or viscosity increase is large Defective (2) Rubber chip molding: Ethylene propylene diene rubber is 2mm in size After blending 15 g of the polyurethane composition of the present invention with 100 g of EPR rubber chips crushed into chips and mixing them well, the one immediately after being applied on an aluminum foil with a thickness of 10 mm is subjected to the following test.
(A) Measurement of pot life: A part of the coated material is allowed to stand at a humidity of 60% and a temperature of 33 ° C., and is manually stirred using a metal spoon to make the pot life the pot life.
(B) Curing property at room temperature: The surface tackiness of the cured product after leaving a part of the coated material to stand for 5 hours at a humidity of 60% and a temperature of 33 ° C. was judged by touching the finger.
Those with no surface tack …………… Excellent with a little tack on the surface… Good With strong tack remaining …………… Bad (c) Room temperature curing foamability: Judgment is made by visual observation according to the following evaluation criteria.
Hardened product with no foaming ……… Excellent with little foaming ………………… Good With much foaming ……… Defective (d) Heat-curing property: Application on the aluminum foil A part of the product is left in an oven at 140 ° C. for 10 minutes immediately after application and then taken out, and the surface tackiness and foaming state are visually observed at room temperature according to the following evaluation criteria.
Good with no surface tack or foaming ………………………………… Slightly tacky or slightly foaming on the surface… Good Good tacky or very foamy …… ………… Defective (e) Tensile strength of molded product: A sample obtained by the above-described evaluation of heat curability was cut into a rectangular parallelepiped shape having a length of 100 mm, a width of 25 mm, and a thickness of 10 mm, and a tensile speed of 500 mm / min. Then, the tensile strength is measured at 23 ° C. and 65% RH with a tensile tester (manufactured by Ueshima Seisakusho).
(3) Property measurement of composition (a) Viscosity measurement of liquid: Measured with a B-type rotational viscometer (manufactured by Tokyo Keiki) at 25 ° C.
(B) Measurement of isocyanate group concentration in liquid By NCO amount measurement of JIS-K1556.

  Except for changing the amount of p-MDI charged as shown in Table 1, the polyurethane compositions of Samples 2 to 4 were prepared in the same manner as in Example 1, and cured products were obtained in the same manner as in Example 1, and the evaluation test was performed. The results are shown in Table 1.

When the isocyanate group concentration in the polyurethane composition is within the range of the present invention, good storage stability and curability and strength of the molded product can be obtained. The pot life is 30 minutes or more, and this value is preferably as long as possible. The room temperature curing property and room temperature curing foamability are all good at the isocyanate concentration within the range of the present invention, and this range is preferable.
In addition, although the molding temperature is evaluated under two conditions of room temperature or 140 ° C., both when there are few or many isocyanate groups, the tackiness remains at 140 ° C. and the heat curability deteriorates such as a lot of foaming. There was, and was not usable.

Comparative Example 1
A polyurethane composition of Comparative Sample 1-2 was prepared in the same manner as in Example 1 except that the amount of p-MDI charged was changed as shown in Table 1, and a cured product was obtained in the same manner as in Example 1. The performance evaluation results are shown in Table 1.

Other than using a mineral spirit solution of ferric octylate (manufactured by Wako Pharmaceutical Co., Ltd.) containing 6% by mass (52% by mass as non-volatile content) of iron instead of a mineral spirit solution of ferrous naphthenate as a curing catalyst Obtained a polyurethane composition of Sample 5 in the same manner as Sample 3.
When the evaluation test was done like Example 1, the viscosity of the obtained liquid was 2300 mPa * s and the isocyanate group density | concentration was 12.1 mass%.
The pot life was 90 minutes, and room temperature curability, room temperature cure foamability, and heat curability were all excellent, and the tensile strength of the molded product was 0.7 MPa.

Instead of a mineral spirit solution of ferrous naphthenate as the curing catalyst, ferrous acetylacetonate (manufactured by Wako Pure Chemical Industries) containing 5% by mass of iron (33% by mass as non-volatile content) diethyl malonate (boiling point 199) The polyurethane composition of Sample 6 was prepared in the same manner as Sample 3 except that the solution was used at 0 ° C., manufactured by Wako Pharmaceutical Co., Ltd.
When an evaluation test was conducted in the same manner as in Example 1, the viscosity of the obtained liquid was 2400 mPa · s, the isocyanate group concentration was 12.2% by mass, and the storage stability of the composition was excellent.
The pot life was 80 minutes, and room temperature curability, room temperature cure foamability, and heat curability were all excellent, and the tensile strength of the molded product was 0.8 MPa.

Comparative Example 2
Polyurethane compositions of Comparative Samples 3 to 5 were prepared in the same manner as in Example except that the catalyst solution and amount shown in Table 1 were used instead of the mineral catalyst solution of ferrous naphthenate as the curing catalyst.
The results are shown in Table 1. Tin compounds have problems in storage stability and pot life, and lead compounds have good liquidity and curability, but are not environmentally preferable. Bismuth compounds have slightly poor curability.
In addition, the catalyst used was the following.
Dibutyltin dilaurate: manufactured by Sansha Co., Ltd. Lead naphthenate: Nikka octix lead 20% (T), containing 20% by weight as lead, and 44% as non-volatile content dissolved in mineral spirit (manufactured by Nippon Kagaku Sangyo)
Bismuth octylate: Nikka Octix Bi 25%, 25% by mass as bismuth, 80% by mass as non-volatile content dissolved in octyl acid (manufactured by Nippon Kagaku Sangyo)

A urethane composition of Sample 7 was prepared by blending 0.2 parts by weight of an antifoaming agent (BYK-052 manufactured by BYK Japan) with 100 parts by weight of the polyurethane composition of Sample 3. The antifoaming agent is a 20% by mass solution of an alkyl vinyl ether copolymer using a mixture of white spirit, butyl glycolate, and ethylene glycol monobutyl ether as a solvent.
When the evaluation test was conducted in the same manner as in Example 1, the composition was excellent in storage stability, pot life was 50 minutes, room temperature curability was excellent, room temperature curing foaming was not observed at all, and an antifoaming agent. The foaming property was improved as compared with Sample 3 in which no was added. The tensile strength of the molded body was 0.7 MPa.

A cured product was obtained in the same manner as in Example 1 except that the oven temperature was set to 80 ° C. in the evaluation of the thermosetting property of the composition of Sample 3. The obtained cured product did not show foaming or tack, and had a good appearance. The tensile strength of the molded body is 0.9 MPa.
While the molded product obtained by the room temperature curability evaluation of Example 3 has some foaming, when the molding temperature is increased as in this example, foaming is not recognized and the molding state is good. The heating temperature is preferably 70 ° C. or higher.

  A polyurethane composition was obtained by blending 0.3 part by weight of an alkyl vinyl ether copolymer solution (manufactured by BYK Japan, trade name BYK-052) with 100 parts by weight of the polyurethane composition of Sample 3. Apply the composition and leave it for 2 days using a 2 mm thick test piece cut out from a polyvinyl chloride rain gutter (made by Takiron) so that the overlapping part is 12.5 mm × 12.5 mm. Prepare an adhesion test specimen sample. The tensile shear bond strength of this test piece was measured according to JIS K6850. The tensile shear bond strength was 3.5 MP, which was a practical bond strength.

Comparative Example 3
A polyurethane composition of Comparative Sample 6 was prepared in the same manner as in Example 1 except that p-MDI was replaced with hexamethylene diisocyanate (HDI) in Example 1 and the reaction time was changed to 20 hours.
When the obtained polyurethane composition was evaluated in the same manner as the evaluation test method described in Example 1, the isocyanate group concentration was 8.9% by mass and the viscosity was 2,000 mPa · s (25 ° C.).

Next, a cured product similar to that of Example 1 was produced using the obtained polyurethane composition. The storage stability of the liquid was excellent, and the pot life when blended with a rubber chip and molded was 200 minutes or more. Met.
On the other hand, it hardly cured at room temperature, and the room temperature curability was poor. The thermosetting property was also poor and the strength was so weak that the molded product could not be tested for tensile strength. This is because the reactivity is slowed down by using an aliphatic polyisocyanate, which is not practical.

  The polyurethane composition of the present invention is a polyurethane composition comprising a urethane prepolymer having an isocyanate group and a curing catalyst, containing 3% by mass or more of an isocyanate group, wherein the curing catalyst is dissolved in a solvent having a boiling point of 150 ° C. or higher. Made of at least one of iron acid and iron acetylacetonate, and the solvent content is 1% by mass or less, the polyurethane composition is excellent in storage stability and has a good appearance with less foaming and no surface tack. It is possible to provide a polyurethane composition free from environmental health problems.

Claims (4)

In a polyurethane composition comprising a urethane prepolymer having an isocyanate group and a curing catalyst, an organic carboxylate iron or iron acetylacetonate containing 3% by mass or more of an isocyanate group and dissolved in a solvent having a boiling point of 150 ° C. or higher. A solvent-free polyurethane composition comprising at least one of them and having a solvent content of 1% by mass or less. 2. The solventless polyurethane composition according to claim 1, wherein the urethane prepolymer is a reaction product of an aromatic polyisocyanate compound and at least one of a polyoxyalkylene polyol and a polyester polyol. The solvent-free polyurethane composition according to claim 1, comprising a polyalkyl vinyl ether compound. The cured product obtained by curing the polyurethane composition is composed of at least one of organic carboxylate iron and iron acetylacetonate in which the isocyanate group concentration is 3% by mass or more and the curing catalyst is dissolved in a solvent having a boiling point of 150 ° C. or more. A cured product obtained by applying a solvent-free polyurethane composition having a solvent content of 1% by mass or less to an adherend and then curing it by heating to 70 ° C. or higher.