JPH05194694A - Polyurethane polyol and polyurethane coating composition using the same - Google Patents

Abstract

PURPOSE:To obtain a quick-drying polyurethane coating composition having high modulus of elasticity and high strength. CONSTITUTION:HO-R-OH (R is 7-20C straight-chain or branched chain alkylene group) is reacted with isophorone diisocyanate to give a polyurethane polyol having 500-20,000 molecular weight. 1,9-Nonanediol or 1,12-dodecanediol may be cited as the preferable diol.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an aliphatic polyurethane polyol containing no polar bond other than urethane bond, which is obtained by reacting a hydrocarbon diol with isophorone diisocyanate, and the use of the same. The present invention relates to a polyurethane coating composition capable of obtaining a coating film which is quick-drying and has a high elastic modulus and strength.

[0002]

2. Description of the Related Art Conventionally, polyurethane is polyester,
A long-chain polyol such as a polyether is synthesized by reacting a short-chain polyol or a diamine with an isocyanate compound, and by optimizing the balance between the soft segment and the hard segment, We have created materials with various desirable mechanical properties. When polyurethane is used as a paint, various properties are required depending on its application. Among them, performances such as quick drying, non-yellowing, mechanical strength, and hydrolysis resistance are strongly desired regardless of the application. It is a thing. In order to improve the drying property, it is well known that a glass transition temperature of the paint is preferably high, and as such a purpose, there are already various acrylic polyols and polyester polyols containing an aromatic ring. Being developed.

[0003]

However, paints using these polyols having a high glass transition point generally have the drawbacks of low elongation at break and brittleness, and are required to satisfy various requirements as described above in a well-balanced manner. Was difficult.

[0004]

[Means for Solving the Problems] In view of the above circumstances, as a result of earnest studies, aiming at development of a polyurethane coating which can be used in various fields where quick drying and high strength are required, a specific aliphatic polyol was found. It has been found that a polyurethane obtained by curing an aliphatic polyurethane polyol composed of and a diisocyanate compound with an appropriate curing agent satisfies the initial target.

That is, the gist of the present invention is that the hydrocarbon diol represented by the general formula (A) is HO-R-OH (A) (wherein R is a linear or branched alkylene group having 7 to 20 carbon atoms). And a number average molecular weight of 500 to 20, obtained by reacting isophorone diisocyanate with
And a coating composition using the same.

[0006] The present invention provides a novel polyol which replaces high molecular weight polyols such as ordinary polyester polyol, polyether polyol and acrylic polyol, and a polyurethane coating composition comprising the same. The novel polyol according to the present invention is a polyurethane polyol synthesized by the reaction of a specific diol and diisocyanate, and has no polar bond other than urethane bond. A polyurethane coating composition containing this polyurethane polyol as a main component is quick-drying, does not have a sticky feeling on the surface, has a high elastic modulus, and does not contain any soft segment composed of high-molecular-weight ether or ester. , 100% or more,
It preferably has a high elongation at break of 200% or more.

The specific diol used in the present invention is an aliphatic hydrocarbon diol represented by the following general formula (A). HO- (R) -OH (A) (In the formula, R represents a linear or branched alkylene group having 7 to 20 carbon atoms.) Specific examples include 1,8-octanediol as a linear diol and 1 , 9-nonanediol,
As branched diols such as 1,12-dodecanediol, 3,3-dimethylolheptane, 2-methyl-1,8-
Octanediol, 2,2,4-trimethyl-1,3-
Examples include pentanediol and 2-ethyl-1,3-hexanediol. Here, when a diol having a carbon number of less than 7 is used, the viscosity of the solution is high, it is difficult to handle, and the breaking elongation of the coating film after curing is small, and only a brittle product is obtained.

On the other hand, when the carbon number is more than 20, the quick-drying and hard urethane which is the object of the present invention cannot be obtained. These diols can be used alone or in admixture of two or more. Of these, linear diols are preferable from the viewpoint of mechanical strength, and those having 8 to 13 carbon atoms are preferable from the viewpoint of availability of raw materials. further,
The diisocyanate compound used in the production of the polyurethane polyol of the present invention is isophorone diisocyanate. Diphenylmethane diisocyanate,
When another isocyanate compound such as hexamethylene diisocyanate is used, the resulting polyurethane polyol is inferior in solubility and insoluble in general organic solvents, which is not preferable.

The reaction of the diol with isophorone diisocyanate can be suitably carried out in the presence or absence of a catalyst at room temperature to 150 ° C. The catalyst may be either a metal-based catalyst such as dibutyltin dilaurate used in the general urethane industry or an amine-based catalyst, and usually 10 to 1,000 per resin solid content.
About ppm is used.

The synthesis of this polyurethane polyol is usually carried out in the presence of a polar solvent such as a ketone type or an ester type. As the solvent, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, butyl acetate, tetrahydrofuran and the like are preferably used.
The number average molecular weight (calculated from the hydroxyl value) of the polyurethane polyol thus obtained is preferably 500 to 20,000, more preferably 1,0.
It is from 00 to 10,000. If the molecular weight is less than 500, the mechanical properties of the cured product will be poor, and if it exceeds 20,000, the viscosity of the solution will be too high, making handling difficult. The range of 1000 to 5000 is most preferable in terms of mechanical strength and handleability.

The aliphatic polyurethane polyol thus produced can be reacted with an appropriate isocyanate compound to form a tough coating film. As the isocyanate compound that can be used here,
It is selected from aliphatic or alicyclic isocyanates. Hexamethylene diisocyanate or isophorone diisocyanate and their derivatives are preferable. Examples of the derivative include an isocyanurate compound, a water adduct, and a polyfunctional polyol to which the isocyanate compound is added to the terminal. Among them, isocyanurate compounds are used for applications requiring high heat resistance, and for applications requiring high elongation at break,
Hexamethylene diisocyanate adducts of polypropylene polyols are preferred. The mixing equivalent ratio when reacting the polyurethane polyol and the isocyanate compound is
Expressed by the molar ratio of the isocyanate group and the hydroxyl group of the polyol, NCO / OH = 0.8 to 1.2, preferably 0.
It is 9 to 1.1.

In the polyurethane coating composition of the present invention, known additives generally used in the urethane industry such as urethane curing catalysts, antioxidants, various disperse dyes, pigments and leveling agents may be added, if necessary. May be added. Thus obtained, the polyurethane coating composition containing an aliphatic polyurethane polyol as a main component is fast-drying because the main component has a high glass transition point, and is a hard and stretchy tough coating film. Become. Furthermore, it satisfies the desirable properties as a coating such as hydrolysis resistance, yellowing resistance, and abrasion resistance, and can be used in a wide range of applications where high mechanical strength is required.

[0013]

EXAMPLES The present invention will be described in detail below with reference to examples, but the invention is not limited to these examples as long as the gist of the invention is not exceeded. The glass transition point was defined as the peak temperature of E "in the dynamic viscoelasticity test at 110 Hz by Rheovibron manufactured by Orientec. For the mechanical strength, a sample was cut into a strip with a width of 1 cm, and the tensile speed was 50 mm / min. At 23 ° C. and a relative humidity of 60%.

The number average molecular weight was measured by the following method since the polyurethane polyol of the present invention has two terminal functional groups and all of them are hydroxyl groups. That is, an excess amount of acetic acid was reacted with an organic solvent solution of the obtained polymer, the amount of unreacted acetic acid was titrated with KOH to determine the amount of reacted acetic acid, and the amount of hydroxyl group was calculated from this. However, in addition to such measurement method,
It can also be theoretically calculated from the charged amount of raw materials.
In the following examples, the hydroxyl value means 1 kg of polymer solution.
This is the weight of KOH required for the titration. Further, in the following, simply having “molecular weight” means the number average molecular weight.

Example 1 A flask was charged with 405 g of 1,9-nonanediol, 495 g of isophorone diisocyanate, and methyl ethyl ketone.
600 g was charged and stirred at 50 ° C. to obtain a uniform solution. Dibutyltin dilaurate 100m as catalyst
g was added, and the reaction was continued for 3 hours. Furthermore, the same amount of catalyst was added, the reaction was continued at 70 ° C for 1 hour, and IR was adjusted to -N.
It was confirmed that CO absorption had disappeared. The thus obtained solution of the aliphatic polyurethane polyol having a molecular weight of about 3,000 is colorless and transparent and has a viscosity of 25 ° C.
It was 2,300 cps and the hydroxyl value was 22.6.

Example 2 A polyurethane polyol solution was prepared in the same manner as in Example 1, except that 280 g of 1,9-nonanediol, 374 g of isophorone diisocyanate and 800 g of ethyl acetate were charged into a flask. The solution of the aliphatic polyurethane polyol having a molecular weight of about 10,000 thus obtained has a viscosity of 3,200 cps at 25 ° C. and a hydroxyl value of 5.
It was 08.

Example 3 450 g of 1,12-dodecanediol, 429 g of isophorone diisocyanate, 58 of methyl ethyl ketone
6 g was placed in a flask and an aliphatic polyurethane polyol solution having a molecular weight of about 3,000 was produced in the same manner as in Example 1. The viscosity of this solution is 1,900 cp at 25 ° C.
s and the hydroxyl value were 22.7.

COMPARATIVE EXAMPLE 1 3-Methyl-1,5-pentanediol was used as the diol, and 3-methyl-1,5-pentanediol was used so that the molecular weight as a polyurethane polyol and the resin solid content concentration were the same as in Example 1.
1,5-Pentanediol 350 g, isophorone diisocyanate 589 g, methyl ethyl ketone 626
g was charged into a flask and a polyurethane polyol having a number average molecular weight of about 3,000 was produced in the same manner as in Example 1. The viscosity of this solution was 8,200 cps at 25 ° C., and the hydroxyl value was 22.3.

Comparative Example 2 Except that the diol was replaced with 1,6-hexanediol,
A polyurethane polyol having a number average molecular weight of about 3,000 was produced in the same manner as in Comparative Example 1. The viscosity of this solution is
It was 6,600 cps at 25 ° C. and the hydroxyl value was 22.4.

Comparative Example 3 Dipropylene glycol 42 was used instead of diol instead of dipropylene glycol so that the molecular weight as a polyurethane polyol and the resin solid content concentration were the same as in Example 1.
2 g, isophorone diisocyanate 478 g, and methyl ethyl ketone 600 g were charged into a flask, and a polyurethane polyol having a number average molecular weight of about 3,000 was produced in the same manner as in Example 1. The viscosity of this solution was 1,900 cps at 25 ° C., and the hydroxyl value was 22.5.

Comparative Example 4 A diol was used as BPX-11 (bisphenol A-propylene oxide adduct manufactured by Asahi Denka Co., Ltd., hydroxyl value 31).
In place of 2), the BPX- was added so that the molecular weight of the polyurethane polyol and the resin solid content concentration were the same as in Example 1.
11 598 g, isophorone diisocyanate 302
and 600 g of methyl ethyl ketone were placed in a flask, and the number average molecular weight was about 3,000 in the same manner as in Example 1.
Was produced. This solution has a viscosity of 2200 cps at 25 ° C. and a hydroxyl value of 22.3.
Met.

Comparative Example 5 The isocyanate compound was replaced with hexamethylene diisocyanate, and 1,9-nonanediol (464 g) and hexamethylene diisocyanate were used so that the molecular weight as a polyurethane polyol and the resin solid content concentration were the same as in Example 1. A flask was charged with 436 g of nato and 600 g of methyl ethyl ketone, and the reaction was carried out in the same manner as in Example 1.
As the reaction proceeded, the inside of the system became cloudy and finally became a waxy solid, which made it unusable as a paint.

Reference Example 1 250 g of G-400 (polypropylene polyol manufactured by Sanyo Kasei Co., Ltd., glycerin-propylene oxide adduct, molecular weight 400, hydroxyl value 420.8) was added to a flask.
Hexamethylene diisocyanate (315 g) and methyl ethyl ketone (141 g) were charged, dibutyltin dilaurate (70 mg) was added as a catalyst, and the mixture was reacted at 50 ° C. for 6 hours to give an isocyanate group content of 2.65 meq / g.
Hardener 1 of was produced.

Reference Example 2 Polypropylene polyol was added to G-600 (molecular weight 60
0, hydroxyl value 280.5), G-600 307
g, hexamethylene diisocyanate 258 g, and methyl ethyl ketone 141 g, and a curing agent 2 having an isocyanate group content of 2.17 meq / g was synthesized in the same manner as in Reference Example 1.

Reference Example 3 400 g of Coronate EH (isocyanurate of hexamethylene diisocyanate) manufactured by Nippon Polyurethane Co., Ltd.
Was dissolved in 100 g of methyl ethyl ketone to prepare a curing agent 3 having an isocyanate group content of 3.29 meq / g.

Examples 4 to 8 and Comparative Examples 6 to 9 The polyols obtained in the above Examples 1 to 3 and Comparative Examples 1 to 4 had an NCO / OH equivalent ratio of 1/1 with the curing agent of Reference Example.
The mixture was mixed so that the film thickness was about 200 μm on a polyethylene plate using a roll coater. The coating film was cured at 80 ° C. for 4 hours and dried to obtain a colorless and transparent film. A strip of test piece was cut out from this film, and a tensile test and dynamic viscoelasticity were measured. The results are shown in Table 1. The films of Comparative Examples 1 and 2 had a small elongation and did not show a falling shape. Further, the films of Comparative Examples 3 and 4 were very brittle, and the test pieces could not be cut out.

[0027]

[Table 1]

[0028]

EFFECTS OF THE INVENTION A polyurethane composition containing an aliphatic polyurethane polyol obtained as a main component according to the present invention is shown in Table 1.
As shown in (1), it has a glass transition point at room temperature or higher, and has a high yield point strength, but also has a high elongation and a tough coating film, and is therefore extremely useful as a coating material.

Claims (2)

[Claims] 1. A hydrocarbon diol HO-R-OH (A) represented by the general formula (A) (wherein R represents a linear or branched alkylene group having 7 to 20 carbon atoms). Number average molecular weight 500 to 20, obtained by reacting isophorone diisocyanate,
Polyurethane polyol characterized by being 000. 2. A polyurethane coating composition comprising the polyurethane polyol of claim 1.