JPH06248044A - Production of polyamide resin, polyamide resin and coating using the same - Google Patents

Abstract

PURPOSE:To obtain the subject resin, soluble in low-boiling general-purpose solvents, excellent in heat resistance and suitable as coatings, etc., by blocking the terminal isocyanate groups of a specific polyamide with a compound having hydroxyl group, etc. CONSTITUTION:The objective resin is obtained by blocking terminal isocyanate groups in a polyamide prepared by reacting (A) a diisocyanate comprising tetramethylxylene diisocyanate of the formula as an essential component with (B) a dicarboxylic acid such as an aliphatic dicarboxylic acid at a molar ratio of the components (A)/(B) substantially within the range of 1<= components (A)/(B)<=2 with a compound having any of hydroxyl, amino and imino groups such as an alkanolamine. Furthermore, this coating is prepared by using this resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyamide resin, a polyamide resin and a paint using the same.

[0002]

2. Description of the Related Art Conventionally, a polyamide resin has a high polarity and a strong hydrogen bond between the nitrogen atom and the carbon atom of its amide bond and has a large bond energy.
Although it has excellent heat resistance, it has a low solubility in organic solvents, and for example, most of it is soluble only in a special high boiling point polar solvent having a large dissolving power such as N-methyl-2-pyrrolidone.

Therefore, for example, when it is applied to a coating resin, heat treatment such as drying and curing at a boiling point of a solvent having a high boiling point or less, that is, when low temperature baking is required, is used in a coating film obtained after baking. However, there is a problem that not only the original coating film performance of the polyamide resin cannot be fully exhibited, but also various adverse effects are caused by the residual solvent, and high-temperature baking that can completely evaporate and volatilize the high boiling point solvent It could only be used for limited purposes.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides a method for producing a polyamide resin soluble in a low boiling point general-purpose solvent, a polyamide resin, and a coating material using the same.

[0005]

Means for Solving the Problems If the present inventor uses a diisocyanate having a bulky alkyl group at a carbon atom adjacent to an isocyanate group, the obtained polyamide resin will have an amide bond due to the steric hindrance effect of the alkyl group. It is thought that the solubility in organic solvents will be dramatically improved by suppressing intermolecular hydrogen bonds, and as a result of extensive studies, a specific polyamide resin obtained from tetramethylxylene diisocyanate is They have found that they are soluble in low boiling point general-purpose solvents and are extremely useful as coating resins.

That is, in the present invention, the molar ratio of diisocyanate (A) containing tetramethylxylene diisocyanate represented by the general formula (I) as an essential component and dicarboxylic acid (B) is substantially 1 ≦. (A) / (B) ≦ 2 The polyamide obtained by the reaction is blocked with a compound (C) having a terminal isocyanate group of any one of a hydroxyl group, an amino group and an imino group. The present invention relates to a method for producing a polyamide resin, a polyamide resin produced by this production method, and a paint using the same.

[Chemical 2]

Diisocyanate (A) in the present invention
In addition to the essential component tetramethylxylene diisocyanate, other diisocyanates can be used. Other diisocyanates are not particularly limited,
For example, diphenylmethane diisocyanate and its water additive, xylene diisocyanate and its water additive,
Tolylene diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, trimethyl hexamethylene diisocyanate, isophorone diisocyanate and transcyclohexane-
1,4-diisocyanate and the like can be mentioned, and these may be used alone or in combination of two or more kinds.

The blending ratio of tetramethyl xylene diisocyanate and other diisocyanate is not particularly limited as long as the obtained polyamide resin composition is soluble in a general solvent having a low boiling point. Tetramethyl xylene diisocyanate is 50 mol% or more in the internal ratio of diisocyanate (A), and other diisocyanate is 5
It is preferred to use less than 0 mol%.

The dicarboxylic acid (B) used in the present invention is not particularly limited, but an aliphatic dicarboxylic acid is most preferable. Examples of the aliphatic dicarboxylic acid include, for example, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and the like, in addition to general aliphatic dicarboxylic acids whose main chain is composed of a methylene chain, ethylene glycol, diethylene glycol, and triethylene. A half-esterified product represented by the general formula (II) obtained by reacting a polyethylene glycol such as glycol with a cycloaliphatic dicarboxylic acid anhydride such as succinic anhydride, or a poly (represented by the general formula (III) of Kawaken Fine Chemical Co., Ltd. Oxyethylene) diglycolic acid and the like can be used, and these can be used alone or in combination.

[Chemical 3] (N represents an integer of 1 to 100)

[Chemical 4] (N represents an integer of 1 to 100)

The diisocyanate (A) and the dicarboxylic acid (B) are reacted in a molar ratio of substantially 1 ≦ (A) / (B) ≦ 2 to form a polyamide having an isocyanate group at the terminal. To do. Molar ratio of (A) and (B) (A) /
When (B) is less than 1, both end groups of the obtained polyamide become carboxyl groups. On the other hand, when (A) / (B) exceeds 2, diisocyanate (A) remains as an unreacted material, which is not preferable.

The carbon dioxide desorption polymerization reaction for producing polyamide from diisocyanate (A) and dicarboxylic acid (B) is a catalyst because tetramethyl xylene diisocyanate has a tertiary isocyanate group and low reactivity. In the temperature range of 80 to 250 ° C., preferably 100 to 200 ° C., in a substantially anhydrous state.

Examples of the catalyst include tertiary amines such as triethylamine, triethylenediamine and N-methylmorpholine, and metal organic acid salts such as dibutyltin dilaurate and 1,3-diacetoxytetrabutylstannoxane. Especially, a tertiary amine is preferable.

As the solvent for the reaction, a solvent which does not inhibit the carbon dioxide desorption polymerization reaction between the diisocyanate (A) and the dicarboxylic acid (B) may be selected and used as necessary.
Considering the ease of completion of the reaction, it is preferable that the reaction system is solvent-free and is kept in a molten and uniform state.

The compound (C) having any one of a hydroxyl group, an amino group and an imino group used in the present invention is a terminal isocyanate group of a polyamide obtained from diisocyanate (A) and dicarboxylic acid (B). There is no particular limitation as long as it can block the alkanol, but alkanolamine is most preferable.

Examples of alkanolamines include:
N, N-dimethylethanolamine, N-methylethanolamine, ethanolamine, diethanolamine,
Examples thereof include triethanolamine, and these may be used alone or in combination of two or more kinds.

The amount of the compound (C) having any one of a hydroxyl group, an amino group and an imino group to be used should be at least twice the molar amount of the diisocyanate (A) with respect to the dicarboxylic acid (B). Is preferred. If the amount of the compound (C) used is less than twice the molar amount, it is impossible to completely block all the terminal isocyanate groups of the polyamide. On the other hand, since the amount of the compound (C) that greatly exceeds the 2-fold molar amount remains as an unreacted product, the upper limit of the amount of the compound (C) used is the excess of the diisocyanate (A) with respect to the dicarboxylic acid (B). The amount is preferably 2.2 times the molar amount.

The reaction of blocking the terminal isocyanate group of the polyamide obtained from diisocyanate (A) and dicarboxylic acid (B) with compound (C) having any one of hydroxyl group, amino group and imino group is substantially carried out. It is carried out in an anhydrous state at a temperature range of 0 to 200 ° C. or lower, preferably 50 ° C. to the boiling point of the compound (C) used. A solvent and a catalyst for the reaction may be used, but the reactivity between the terminal isocyanate group of the polyamide and the compound (C) is relatively high, and the reaction is completed rapidly, so that it is not particularly necessary.

In the present invention, it is most preferable to carry out the synthesis reaction in a uniform state in which the reaction system is melted throughout all steps, and after blocking the terminal isocyanate group, a general solvent having a desired low boiling point is used. It can be dissolved into a predetermined concentration to form a coating material.

A low boiling point general-purpose solvent has a boiling point of 150.
There is no particular limitation as long as it dissolves the polyamide resin composition of the present invention at a temperature of not higher than ° C. Examples of applicable low-boiling general-purpose solvents include aliphatic lower alcohols such as n-propanol, isopropanol, and n-butanol; aliphatic esters such as ethyl acetate and n-butyl acetate; and aliphatic esters such as methyl ethyl ketone and methyl isobutyl ketone. Ketone,
Examples thereof include those commonly used in the field of coating materials such as aromatic hydrocarbons such as toluene and xylene, and these may be used alone or in combination of two or more kinds.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 226.9 g (0.929 mol) of m-tetramethylxylene diisocyanate in a 1 liter separable flask equipped with a stirrer, a thermometer, a cooling condenser and a nitrogen gas introducing tube under a nitrogen atmosphere. Sebacic acid 94.0
g (0.465 mol) and triethylenediamine 0.5
7 g (0.005 mol) was added and the temperature was raised to 130 ° C. During the temperature rising process, the reaction system became molten and became a uniform state, and generation of carbon dioxide was observed. After raising the temperature, at the same temperature for 2 hours,
Then, the reaction was allowed to proceed at 170 ° C. for 2 hours to obtain a polyamide having isocyanate groups at both ends. When the infrared absorption spectrum of this polyamide was measured, the appearance of carbonyl absorption due to an amide bond at 1658 cm ^-1 was 228.
Absorption based on an isocyanate group was observed at 0 cm ^-1 .
Then, while keeping this polyamide at 130 ° C,
86.9 g of N, N-dimethylethanolamine
(0.975 mol) was added dropwise over 10 minutes, and the reaction was allowed to proceed at the same temperature for 1 hour to obtain a polyamide resin. The infrared absorption spectrum of this polyamide resin was measured and found to be 16
58cm ^-1 absorption of a carbonyl based amide bond was observed, the disappearance of the absorption due to the isocyanate groups of the appearance and 2280 cm ^-1 absorption of a carbonyl-based ester bond of the urethane bond to 1715 cm ^-1 were observed. This product was dissolved in n-butanol by 50% by weight or more.

Example 2 In a synthesizer similar to that described in Example 1, 14.5 g (0.234 g) of ethylene glycol was added under a nitrogen atmosphere.
Mol), diethylene glycol 24.9 g (0.235
Mol), succinic anhydride 93.8 g (0.937 mol) and triethylenediamine 0.57 g (0.005 mol)
Was charged and the temperature was raised to 100 ° C. During the temperature rising process, the reaction system became molten and became a uniform state. After the temperature was raised, the reaction was allowed to proceed for 2 hours at the same temperature to obtain a liquid mixture of dicarboxylic acid represented by the following general formula (II). The infrared absorption spectrum of this dicarboxylic acid was measured to find that at 1740 cm ^-1 the broad absorption of the carbonyl based on the ester bond of the terminal carboxyl group and the carbonyl based on this and the ester bond located through the two methylene chains was observed. Appearance and 1785 cm ^-1
And disappearance of carbonyl absorption based on the anhydride group of succinic anhydride at 1870 cm ^-1 .

[Chemical 5] (N = 1 is 50 mol%, n = 2 is 50 mol%) Next, this dicarboxylic acid was cooled to room temperature, and then m-tetramethylxylene diisocyanate 229.
0 g (0.937 mol) was added, and a polyamide having an isocyanate group at both ends was obtained by the same synthetic procedure as in Example 1. Then, this polyamide is heated to 130 ° C.
While keeping the temperature at 1, 87.7 g (0.984 mol) of N, N-dimethylethanolamine was added dropwise thereto over 10 minutes, and the reaction was allowed to proceed at the same temperature for 1 hour to obtain a polyamide resin of the present invention. In the infrared absorption spectrum of this polyamide resin, absorption of carbonyl based on amide bond and urethane bond was observed, and absorption based on isocyanate group was not observed at all, as in Example 1. This one is
As in Example 1, 50% by weight or more was dissolved in n-butanol.

Example 3 186.0 g of poly (oxyethylene) diglycolic acid represented by the following general formula (III) was used as the dicarboxylic acid.
A polyamide resin of the present invention was obtained in exactly the same manner as in Example 1 except that (0.465 mol) was used. In the infrared absorption spectrum of this polyamide resin, absorption of carbonyl based on amide bond and urethane bond was observed, and absorption based on isocyanate group was not observed at all, as in Example 1. This was dissolved in n-butanol at 60 wt% or more, and in methyl ethyl ketone and n-butyl acetate at 30 wt% or more.

[Chemical 6] (N = 6)

Comparative Example 188.0 g of m-xylene diisocyanate was added to a synthesizer similar to that described in Example 1 under a nitrogen atmosphere.
(1.000 mol), and 200.0 g (0.500 mol) of poly (oxyethylene) diglycolic acid used in Example 3 were added, and both groups of isocyanate groups were added by the same synthetic procedure as in Example 1. A polyamide having terminals was obtained. Then, while keeping the polyamide at 130 ° C., N, N-dimethylethanolamine 93.6 was added thereto.
g (1.050 mol) was added dropwise over 10 minutes and the reaction was allowed to proceed at the same temperature for 1 hour to obtain a polyamide resin for comparison with the present invention. In the infrared absorption spectrum of this polyamide resin, absorption of carbonyl based on amide bond and urethane bond was observed, and absorption based on isocyanate group was not observed at all, as in Example 1. This one is N
-Soluble in methyl-2-pyrrolidone, but n-
It was insoluble in low boiling point general-purpose solvents such as butanol, methyl ethyl ketone and n-butyl acetate.

[0024]

The polyamide resin obtained by the method for producing a polyamide resin of the present invention is soluble in a general solvent having a low boiling point, and thus can be applied to a wide range of applications and is extremely useful as a resin for paints.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C09D 177/00 PLS 9286-4J

Claims (5)

[Claims] 1. A diisocyanate (A) containing tetramethylxylene diisocyanate represented by the general formula (I) as an essential component and a dicarboxylic acid (B) in a molar ratio of substantially 1 ≦ (A) / (B) Production of a polyamide resin characterized in that the terminal isocyanate group of the polyamide obtained by reacting within the range of ≦ 2 is blocked with a compound (C) having any one of a hydroxyl group, an amino group and an imino group. Law. [Chemical 1] 2. The method for producing a polyamide resin according to claim 1, wherein the dicarboxylic acid (B) is an aliphatic dicarboxylic acid. 3. The method for producing a polyamide resin according to claim 1, wherein the compound (C) having any one of a hydroxyl group, an amino group and an imino group is an alkanolamine. 4. A polyamide resin produced by the method for producing a polyamide resin according to claim 1, 2. 5. A paint using the polyamide resin according to claim 4.