JPH09278864A - Two-component curable polyurethane resin composition and method for producing the same - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a moisture-curable urethane composition which has no increase in initial viscosity, has a long pot life, and is excellent in strength appearance, and a method for producing the same. The present invention provides (I) a urethane prepolymer having two or more isocyanate groups at the terminal of the molecule, (II)
A two-component curable polyurethane resin composition comprising a reaction compound of an unreacted organic polyisocyanate compound and N-2-hydroxyalkyloxazolidine in the reaction of urethane prepolymer (I), (III) polyol and / or polyamine It is to provide things.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention includes a reaction product of an organic polyisocyanate compound and N-2-hydroxyalkyloxazolidine (hereinafter, abbreviated as hydroxyoxazolidine), and thus when mixed with a curing agent and cured. The thermosetting type suppresses an increase in the initial mixing viscosity and prolongs the pot life, and the room temperature curable type suppresses an increase in the initial mixing viscosity, prolongs the pot life and is capable of rapidly developing strength. TECHNICAL FIELD The present invention relates to a two-component curable polyurethane resin composition and a method for producing the same.

[0002]

2. Description of the Related Art Curable urethane resins are used in various fields. For example, there are two types of curable urethane that cures urethane prepolymers using polyamines and polyols alone or in combination as a cross-linking agent, that is, heat-curing type that cures by heat and room-temperature curing type that cures at room temperature. The curing type urethane resin is widely used for forming iron, paper feed rolls, transfer rolls for printing, solid tires for transportation equipment, and the like. Similarly, it is known that a combination of a polyisocyanate compound and a polymer solution containing active hydrogen is used as a thermosetting paint in automobiles, home appliances, industrial materials and the like. Further, the room temperature curing type is used in various fields such as the above-mentioned applications, molding, injection sealing, paints and coating materials.

In these two-component reaction type curable urethane resins, the balance between the pot life and the curing time is important except for special cases in use. It is required to mix an organic polyisocyanate compound and an active hydrogen compound and to take an appropriate working time required for casting, pouring, coating, etc., that is, a pot life. Then, it is required to cure as quickly as possible after finishing the operations such as casting, pouring and coating. Normally, if the curing is to be accelerated, the pot life needs to be shortened, and if the pot life is lengthened, the curing time also becomes longer accordingly. In this way, it is possible to adjust either one of the pot life and the curing time, but the most preferable pot life is long and the curing time does not change or can be shortened, that is, the working time is sufficient. Therefore, it is very difficult to design the one that has the same strength or does not change in speed.

Especially, the room temperature curing type has many applications to be used in the outdoor natural environment, and the reactivity of these curable urethanes is high in the high temperature in summer and the pot life becomes short, and in the low temperature in winter. Has a property that the reactivity is slow and the pot life is extended, but at the same time, the curing time is long and the strength development takes time, so that a good balance of long pot life and short curing time is maintained in all seasons. That is especially difficult.

Further, when the amount of unreacted organic polyisocyanate that has not reacted with the polyol is large in the urethane prepolymer obtained by the reaction of the polyols and the organic polyisocyanate, the initial viscosity when mixed with the curing agent is increased and the workability is improved. Deteriorate. For example, in the case of cast urethane, it is difficult to pour it into a small mold and it is difficult to obtain a complete molded product.
In the case of coating a room temperature curing type paint, a coated flooring material, a roof waterproofing material, etc., if the initial viscosity is likely to increase, the coating work becomes difficult and the surface finish tends to be poor.

In the prepolymerization reaction of the polyols and the organic polyisocyanate, the number of isocyanate group equivalents / the number of hydroxy group equivalents is 2.0 or less, the urethane prepolymer obtained does not react with the polyols. Free organic polyisocyanate is present. This is a combination of polyols and isocyanates having different reactivities, but the amount of residual free organic polyisocyanate is different, but about 0.3 to 7% remains, which causes various problems when combined with a curing agent. Generally, unreacted isocyanate monomer is highly toxic to human body, and therefore its concentration is strictly regulated from the viewpoint of legal regulation. For example, there are regulations on labeling and handling according to the Industrial Safety and Health Law, regulations on allowable concentrations by the Japan Society for Occupational Health, etc. By using the means of the present invention, it is possible to reduce toxicity and even to be out of the subject of regulation.

[0007]

DISCLOSURE OF THE INVENTION The present invention improves the above-mentioned drawbacks, that is, suppresses an increase in initial viscosity of mixing, prolongs pot life, and accelerates strength development. It is to provide a composition.

[0008]

As a result of earnest research to solve the above-mentioned problems, the present inventors have solved these problems by using a reaction product of a urethane prepolymer, hydroxyoxazolidine and an organic polyisocyanate. The inventors have found that they can be solved and completed the present invention.

That is, the present invention provides (I) a urethane prepolymer having two or more isocyanate groups at the terminal of the molecule, (I
I) A reaction compound of an organic polyisocyanate and N-2-hydroxyalkyloxazolidine, (III) a polyol and / or a polyamine, preferably a urethane prepolymer (I) having a primary or secondary hydroxyl group in the molecule. An unreacted organic polyisocyanate in the reaction of the urethane prepolymer (I), wherein the reactive compound (II) has two or more isocyanate groups at the terminal of the molecule obtained by the reaction of a polyol having two or more And a N-2-hydroxyalkyloxazolidine as a reaction compound, and an isocyanate group at the molecular end obtained by the reaction of a polyol having two or more primary or secondary hydroxyl groups in the molecule with an organic polyisocyanate is 2 A reaction step for obtaining a urethane prepolymer (I) having one or more A method for producing a two-component curing type polyurethane resin, which comprises reacting an unreacted organic polyisocyanate that has not reacted with a polyol in the synthesis reaction of the repolymer (I) and N-2-hydroxyalkyloxazolidine, preferably The reaction between the unreacted organic polyisocyanate and N-2-hydroxyalkyloxazolidine reacted more than half of the unreacted isocyanate groups, and for the thermosetting type, the increase in mixing initial viscosity was suppressed and the pot life was extended. In the room temperature curing type, a two-component curing type polyurethane resin composition capable of suppressing an increase in the initial viscosity of mixing, prolonging the pot life, speeding up the strength development, strongly reducing toxicity, and improving safety can be provided. It is provided.

The present invention will be further described below.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The urethane prepolymer (I) having two or more isocyanate groups at the terminal of the molecule of the present invention is preferably a polyol having two or more primary or secondary hydroxyl groups in the molecule and an organic compound. It is obtained by reaction with polyisocyanate. Its NCO / OH equivalent ratio is preferably 1.6 or more, particularly preferably 1.8.
４4.0. The residual NCO% is preferably 1 to 15
% By weight. The number of terminal isocyanate groups is preferably 2-3.

The polyols having two or more primary or secondary hydroxyl groups in the molecule used in the present invention include, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1.4 butanediol, trimethylolpropane and the like. Single chain polyols of
These single-chain polyols and alkylene oxides (for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, etc.) are polymerized alone or in combination to produce polyalkylene ether polyols or by esterification reaction of dibasic acid and single-chain glycol. The obtained polyester polyols, castor oil,
Examples thereof include polybutadiene polyol and polyols of a polyol type xylene formaldehyde resin as a simple substance or a mixture thereof. This polyol preferably has a number average molecular weight of 500 to 16000 and is preferably a polyether polyol. More preferred are polyether diols and / or polyether triols. Other,
Urethane polyols such as polycarbonate polyol and polybutadiene polyol can also be used.

The organic polyisocyanate to be reacted with these polyols is, for example, tolylene diisocyanate (80/80) having two or more free isocyanate groups in the molecule and having an isomer ratio of 2,4 / 2,6 = 80/20. 20TD
I), 65/35 TDI, 2,4-100 TDI, diphenylmethane 4,4'-diisocyanate (pure or monomeric MDI), polymeric MDI, crude MDI, hexamethylene diisocyanate (HD
I), trans-cyclohexa-1,4-diisocyanate (CHDI), isophorone diisocyanate (IPD
I), m-xylene diisocyanate (XDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), 4.4'-diphenylmethane triisocyanate (Desmodur RI) or a single substance or a mixture thereof can be used.

The organic polyisocyanate compound (II) may be not only the above-mentioned organic polyisocyanate but also a urethane prepolymer having an isocyanate group formed by reacting an organic polyisocyanate with a polyol. Preferred is a free organic polyisocyanate remaining in the urethane prepolymer (I).

The N-2-hydroxyalkyloxazolidine preferably blocks more than half of the unreacted organic polyisocyanate groups, for example 2-isopropyl-3-
(2-hydroxyethyl) -1,3 oxazolidine, 2
-Pentyl-3-oxazolidineethanol, 2- (1
-Methylbutyl) -3-oxazolidineethanol and the like can be used, and a single substance or a mixture thereof can be used.

These hydroxyoxazolidine compounds are obtained by the condensation reaction of aldehydes such as formaldehyde, acetaldehyde, propyl aldehyde, butyraldehyde, pentyl aldehyde, hexyl aldehyde, octyl aldehyde and benzaldehyde with di (hydroxyalkyl) amine. is there.

The polyols used as the curing agent for the urethane prepolymer (I) or the polyamines having an amino group are the polyols used for preparing the above-mentioned urethane prepolymer (I), and examples of the polyamines include 3 , 3'-dichloro-4,4'-diaminodiphenylmethane (hereinafter referred to as MOCA), 4,4'-diaminodiphenylmethane, diethyltoluenediamine (trade name: Etacure 100: manufactured by Ethyl Corporation),
Further, a mixed liquid of a condensation product of orthochloroaniline and formaldehyde, which is called MOCA, and a plasticizer or a polyether polyol (trade name: Iharacuamine ML-
150, ML-520, ML-530: all manufactured by Ihara Chemical Co., Ltd., or bisamine SL-5707: manufactured by Wakayama Seika Kogyo Co., Ltd.) and other known and commonly used aromatic polyamines are used. And these can be used individually or as a mixture.

In the urethane prepolymer (I) of the present invention, it is preferable that at least half of the unreacted organic polyisocyanate groups that have not reacted with the polyol be subjected to an addition reaction with hydroxyoxazolidine to obtain the compound (II). The amount of unreacted organic polyisocyanate in (I) and the amount of unreacted organic polyisocyanate of urethane prepolymer (I) in which hydroxyoxazolidine is added to the unreacted organic polyisocyanate group can be quantified by gas chromatography. When half of the unreacted organic polyisocyanate groups are blocked with hydroxyoxazolidine, it is necessary to add more than the theoretical amount of hydroxyoxazolidine in order to react with polyols to add a small amount of hydroxyoxazolidine to the polymer chain having an isocyanate group at the molecular end. There is. The excess amount is not constant because the reactivity of polyols and isocyanates are different.

When the urethane prepolymer (I) is used as a polyol, or a polyamine having an amino group, or a mixture thereof as a curing agent, the isocyanate group equivalent number and the hydroxyl group of the polyol, the active hydrogen group equivalent number of the amino group, That is, the NCO / H ⁺ equivalent ratio is preferably in the range of 0.5 to 2.0, and particularly preferably in the range of 0.7 to 1.5.

The urethane resin composition of the present invention contains a primary plasticizer such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate (DOA), chlorinated paraffin, or a phosphoric ester, if necessary depending on the application. Or flame retardant plasticizer, calcium carbonate,
Inorganic fillers or pigments such as clay, talc, titanium white, red iron oxide, etc., or solvents such as toluene, xylene, ethyl acetate, and terpenes alone or in combination for the purpose of reducing the viscosity and increasing the amount of urethane prepolymer (I) or a curing agent It may be added to either one in advance, or may be added directly when the two liquids are mixed. When these thickeners and extenders are added to the urethane prepolymer (I), they are dehydrated and dried by a known method because the isocyanate group and the hydroxyoxazolidine derivative blocking the isocyanate group are deteriorated when water acts. It is important to use it later.

When the urethane prepolymer (I) or the mixture of (I) and (II) is mixed with the curing agent, directly,
Even when the viscosity reducing agent and the bulking agent are added as the third component, it is desirable to dehydrate and dry as described above.
In order to eliminate such a difficult operation, it is preferable to add the dehydrated and dried viscosity reducer and extender to the curing agent in advance.

Further, when the urethane prepolymer (I) or the mixture of (I) and (II) is combined with a curing agent and cured, a known amine or organometallic compound, etc., which is known and commonly used for promoting the urethanization reaction, is used. A urethanization catalyst can be used. It is added to the curing agent side in advance, or is added directly when the urethane prepolymer (I) and the curing agent are mixed and used to adjust the pot life and the curing time. I can't control the balance of time.

As described above, the two-component curable polyurethane resin composition of the present invention thus obtained is a room temperature curable type, which suppresses an increase in the initial viscosity of mixing and prolongs the pot life of the thermosetting type. With regard to (2), it is possible to provide a two-part curable polyurethane resin composition that suppresses an increase in initial viscosity of mixing, prolongs the pot life, accelerates strength development, and is safer in handling.

The applications of the present invention include thermosetting paints for automobiles, home appliances, industrial materials, etc., and room-temperature curing types include molding, injection sealing, paints and civil construction materials in addition to the above-mentioned applications. Can be used.

[0025]

When the composition of the present invention is used, the curing time of the thermosetting type is not shortened as compared with the room temperature curing type, because the reaction product of the hydroxyoxazolidine and the isocyanate group contained in the compound (II) is the room temperature curing type. In the case of, the pot life is long, and since it is cured in the air, it also comes into contact with water, and the hydroxyoxazolidine reaction product hydrolyzes to form a secondary amino group, which acts as a cross-linking agent that reacts with other isocyanate groups. It is thought to be because.

On the contrary, the thermosetting type is considered to have a relatively short pot life, and since the curing and curing also immediately perform the heat treatment, there is no opportunity to come into contact with moisture during curing and the hydroxyoxazolidine reaction product does not hydrolyze. To be

[0027]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Also,
"Parts" and "%" in the examples represent parts by weight unless otherwise specified.

Examples 1 to 4 and Comparative Examples 1 to 2 I. <Production of Urethane Prepolymer (I)> A 2 L flask had a molecular weight of 1000 (hydroxyl value: 112.2).
KOHmg / g) polypropylene ether glycol (Dainippon Ink and Chemicals, Hyprox DP-10
00) 1000 parts, 80/20 tolylene diisocyanate 348 parts were added, and the reaction was continued at 80 ° C. for 6 hours in a nitrogen stream. The urethane prepolymer (I) thus obtained had a free isocyanate amount of 6.23% and a viscosity of 18000 cps at 25 ° C. Unreacted 80 in this urethane prepolymer by gas chromatography
The amount of / 20 tolylene diisocyanate was quantitatively analyzed by gas chromatography, and the result was 2.10%.
Met.

II. <Production of Reaction Product with Hydroxyoxazolidine> Next, 300 parts of this prepolymer was added with the types and amounts of hydroxyoxazolidine shown in Table 1, and the mixture was placed in a nitrogen stream.
In order to make the reaction milder, the reaction was continued at 50 ° C. for 6 hours to carry out the urethanization reaction between the active hydrogen group of hydroxyoxazolidine and the free isocyanate group to obtain a final urethane composition. Unreacted 80/20 reduced
The TDI amount was determined by gas chromatography quantitative analysis. The property values of the urethane prepolymer were as shown in Table 1.

[0030]

[Table 1] * Addition amount is based on 100 parts of urethane prepolymer (I) A: 2-isopropyl 3- (2-hydroxyethyl) -1,3 oxazolidine B: 2- (1-methylbutyl) -3-oxazolidine ethanol

<Production of thermosetting casting urethane> 300c
c In the flask, the urethane prepolymer 200 shown in Table 1 above is used.
MOCA dissolved in 120 ° C., which is a typical crosslinking agent for thermosetting casting urethane at 80 ° C., and 35.
After adding 7 parts and stirring and mixing uniformly by a known stirring and defoaming method, initial mixing viscosity and pot life were measured. Separately, the mixture is mixed between the glass plates with a thickness of 10 mm so that the thickness is 2 mm.
It was quickly cast into an aluminum dish having a size of mm, cured and cured in a dryer at 100 ° C., and the hardness appearance was observed. The results are shown in Table-2. The physical properties after curing are shown in Table-3.

[0032]

[Table 2]

[Test method] Initial mixing viscosity: 80 ° C Table-1 A predetermined amount of MOCA dissolved in 120 ° C, which is a crosslinking agent, was added to the urethane prepolymer and mixed, and then, using a BM type viscometer (manufactured by Tokyo Keiki). Measured. It refers to the viscosity (CPS) after 3 minutes of mixing.

Pot life: A predetermined amount of MOCA dissolved in 120 ° C., which is a crosslinking agent, was added to the urethane prepolymer shown in Table 1 at 80 ° C. and mixed, and then measured with a BM type viscometer. 10
It means the time (seconds) to reach 10,000 CPS.

Hardness appearance: After mixing the urethane prepolymer shown in Table 1 and MOCA by the above-mentioned operation, aluminum alloy
Then, place it in a dryer at 100 ° C and then JISK
6301 (Vulcanized rubber physical test method) is measured using a specified hardness meter, and it means the time until the hardness reaches 90 degrees.

<Physical Properties of Thermosetting Urethane> After curing the castings of Comparative Examples and Examples obtained in Table 2 in a dryer at 100 ° C. for 10 hours, JISK6301 (vulcanized rubber physical test method) A hardness test with a specified hardness meter and a tensile test with a No. 3 dumbbell were performed.

[0037]

[Table 3]

Examples 7 to 10 and Comparative Examples 3 to 4 (Production of urethane roof coating waterproofing material) I. <Production of urethane prepolymer (I-2)> Polypropylene ether glycol having a molecular weight of 2000 in a 2 L flask. 2,500 parts of Hi-Prox DP-2000 manufactured by Dainippon Ink and Chemicals, and 500 parts of polypropylene ether triol having a molecular weight of 3000 (Hi-Prox TG-3000 manufactured by Dainippon Ink and Chemicals)
174 parts of tolylene diisocyanate having an isomer ratio of 4 / 2,6 = 80/20 was added, and the reaction was continued at 80 ° C. for 6 hours. The viscosity of the obtained urethane prepolymer is 8700 cps at 25 ° C., and the amount of free isocyanate is
The amount of unreacted 80/20 TDI was 3.5% and 1.5%.

II. <Production of reaction product with hydroxyoxazolidine> To 300 parts of this prepolymer, hydroxyoxazolidine shown in Table 4 was added, and the reaction was continued at 50 ° C. for 6 hours to make the reaction milder in a nitrogen stream. A urethane formation reaction between the active hydrogen group of hydroxyoxazolidine and the isocyanate group was carried out to obtain a final urethane prepolymer. The property values of the urethane prepolymer were as shown in Table 4.

[0040]

[Table 4] * Addition amount is based on 100 parts of urethane prepolymer (II-2) A: 2-isopropyl 3- (2-hydroxyethyl) -1,3 oxazolidine C: 2-pentyl-3-oxazolidine ethanol

<Production of curing agent> MOCA was added to 40 parts of polypropylene ether glycol having a molecular weight of 3200 (manufactured by Dainippon Ink and Chemicals, Pandex OD-X-825).
Dioctyl phthalate 35 was added after 6 parts were heated and dissolved.
Part, calcium carbonate (Nitto Koka, NS-200) 10
A total of 200 parts of 9 parts, 5 parts of pigment chrome oxide green, 4 parts of 24% lead octylate solution, and 1 part of stabilizer were kneaded with a three-roll paint roll, and had a green color and a viscosity of 1400.
A curing agent of 0 cps was obtained.

<Production of cured coating film> 50 parts of the urethane prepolymer obtained in Table 4 and 100 parts of the curing agent were placed in a beaker and uniformly mixed with stirring. With this mixture, the initial viscosity, pot life and physical properties after curing were measured. To measure the physical properties, it was applied evenly on a horizontal plate treated with a release agent to a thickness of 2 mm, and cured and cured at room temperature for 7 days.
In 301 (vulcanized rubber physical test method), a hardness test with a specified hardness meter, a tensile test with a No. 3 dumbbell, and a B-type tear strength were measured. The properties are described in Table-5 and the physical properties are described in Table-6.

[0043]

[Table 5]

[Test Method] Initial Mixing Viscosity: A predetermined amount of a curing agent was added to the urethane prepolymer of Table 4 at 25 ° C. and mixed, and then measured with a BM type viscometer. It refers to the viscosity (CPS) after 3 minutes of mixing.

Pot life: A predetermined amount of a curing agent was added to the urethane prepolymer of Table 4 at 25 ° C. and mixed, and then measured with a BM type viscometer. It means the time (seconds) to reach 100,000 CPS.

Hardness appearance: After a predetermined amount of a curing agent was added to the urethane prepolymer shown in Table 4 and mixed by the above-mentioned operation,
Cast it on an aluminum dish and leave it in a room at 25 ° C.
It is the time required to reach a hardness of 30 degrees measured by using a specified hardness meter in SK6301 (vulcanized rubber physical test method).

[0047]

[Table 6] Table-6 Cured physical properties of urethane waterproof membrane

As shown in Comparative Examples 1, 2 and 1-1, 2-1, and Examples 1-5 and 1-1-5-1, the thermosetting type two-component urethane is the comparative example. The initial viscosity is low and the pot life is extended. The hardness appearance, which is a measure of strength appearance, is not delayed as compared with the comparative example. The physical properties of the final cured product were also superior to those of the comparative example.

Similarly, in the waterproof coating material for urethane roof, when comparing the comparative example with the example, the strength appearance becomes faster in comparison with the above-mentioned thermosetting type.

[0050]

According to the present invention, when a prepolymer and a curing agent are mixed and cured, a thermosetting type can suppress an increase in the initial viscosity of mixing and can extend the pot life. As for the room temperature curable type, it is possible to provide a two-part curable polyurethane resin composition capable of suppressing an increase in the initial viscosity of mixing, prolonging the pot life and speeding up the strength development.

Claims (4)

[Claims] 1. An isocyanate group at the molecular end of (I) 2
A two-component curable polyurethane resin composition comprising a urethane prepolymer having two or more thereof, (II) a reaction compound of an organic polyisocyanate compound and N-2-hydroxyalkyloxazolidine, and (III) a polyol and / or a polyamine. 2. The urethane prepolymer (I) has two or more isocyanate groups at a molecular end obtained by reacting a polyol having two or more primary or secondary hydroxyl groups in the molecule with an organic polyisocyanate. The two-component curing according to claim 1, wherein the reactive compound (II) is a reactive compound of an unreacted organic polyisocyanate and N-2-hydroxyalkyloxazolidine in the reaction of the urethane prepolymer (I). -Type polyurethane resin composition. 3. A urethane prepolymer (I) having two or more isocyanate groups at the molecular end obtained by the reaction of a polyol having two or more primary or secondary hydroxyl groups in the molecule with an organic polyisocyanate. In the reaction step, the unreacted organic polyisocyanate that did not react with the polyol in the synthesis reaction of the urethane prepolymer (I) and N-
A method for producing a two-component curing type polyurethane resin, which comprises reacting with 2-hydroxyalkyloxazolidine. 4. An unreacted organic polyisocyanate and N-2.
The two-part curable polyurethane resin composition according to claim 2, wherein the reaction with -hydroxyalkyloxazolidine reacts with more than half of the unreacted isocyanate groups.