JPH05247405A - Curing agent for coating agent - Google Patents

Abstract

PURPOSE: To obtain a coating agent composition which has storage stability and forms a thermosetting film with good properties by making the composition contain an N,N'-dialkylalkylene diamine in an amount sufficient to cure the composition into a blocked isocyanate.

CONSTITUTION: The coating agent composition is obtained by incorporating (B) an N,N'-dialkylalkylene diamine of a formula, where X represents 2-6, R and R' separately represent an alkyl group, such as N,N'-diisopropyl ethylene diamine, in an amount sufficient to cure the composition into (A) a blocked isocyanate. Although it is known that N,N'-di-tert-butyl ethylene diamine is effective as an epoxy curing agent, the diamine is not suitable as a curing agent for isocyanate compounds. The compound B is useful as a curing agent for the compound A, forming a thermosetting film, which exhibits superior storage stability to products cured by other amines.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to hardeners for coatings. More specifically, the present invention relates to certain N,
It relates to the use of N'-dialkylalkylenediamines as hardeners for blocked isocyanate coatings. The coatings made from the products of the invention have better storage stability than those with other hardeners. In addition, thermoset films made from these coatings have excellent properties.

[0002]

It is known in the art to combine various compounds with isocyanates to obtain coating compositions having various desired properties.

US Pat. No. 4,590,254 discloses non-aqueous poly (urethane-ureas). It is prepared by back-adding an isocyanate group-terminated prepolymer to an organic medium containing an alcohol solvent and a chain extender containing at least two isocyanate group-reactive active hydrogen groups.

In US Pat. No. 4,490,520, a reaction product of (1) an alkali catalyst and (2) a polyfunctional co-catalyst with a polyoxyalkyleneamine is contacted with an ω-lactam. Disclosed is a method for producing an impact-resistant polyamide, which comprises polymerizing. Polyamides made by this process are particularly useful for making tough molded or cast products.

Wolf et al., US Pat. No. 4,495,229
U.S. Pat. No. 6,968,961 discloses a one-component thermosetting coating for polyurethanes made from a polyol compound having a low glass transition temperature and a blocked polyisocyanate, which cures above 120 ° C. and is storage stable. Where the blocked isocyanate is the reaction product of a polyisocyanate compound and a secondary amine.

As illustrated in US Pat. No. 4,761,465, the novel difunctional isocyanate prepolymers are synthesized from polyoxyalkylene diamines and diisocyanates. This new product is
It contains at least two urea and two active isocyanate groups linked by a polyoxyalkylene moiety.

It is known that some drugs reduce side reactions of isocyanates during storage. U.S. Pat. No. 4,590,009 describes the addition of 50 to 5,000 ppm of hydrazine hydrate to a compound having a free isocyanate group, based on the amine reacted with a polyisocyanate group. Methods for reducing side reactions during manufacture and storage are disclosed.

A good overview of blocked isocyanates can be found in Water-Borne and Highye, February 5-7, 1986, New Orleans, Louisiana.
Mobay Chem presented at r-Solids Conference
found in Mobay's publication entitled "Blocked Isocyanates in Coatings" by ical. Background, properties of blocked polyisocyanates and blocking agents,
Many aspects of isocyanate chemistry, including raw materials and advantages, are described.

Partially alkoxylated polyoxyalkylene amines have been used as hardeners. U.S. Pat. No. 4,767,836 discloses a storage stable polyurethane coating composition that can be heat cured under relatively mild conditions. It contains a hardener consisting of chemically blocked isocyanates and partially alkoxylated polyoxyalkylene amines.

In US Pat. No. 2,151,643 of USM Corporation, (a) a polyurethane prepolymer formed by the reaction of a polyisocyanate and a polyol, (b) a blocking agent, and ( c)
Disclosed is a thermosetting composition containing a curing agent composed of amine-terminated polyoxypropylene polyether triol.

A one-container polyurethane system which has the advantage of being easy to handle is described in US Pat. No. 4,624,9.
No. 96. This system comprises an isocyanate group terminated polyurethane prepolymer whose isocyanate groups are blocked by reaction with an oxime and a curing agent having at least two active hydrogen atoms per molecule.

US Pat. No. 4,906,774 describes a series of new diamines prepared by the reaction of polyoxyalkylene diamines with diisocyanates.

Virginia Chemi, Portsmouth, Virginia
The Cal Company product description "Amines" provides a great deal of knowledge about the properties of various amines.

[0014]

It is always of interest in the art to identify compounds that are useful as hardeners for coatings, especially those that impart improved storage stability to the product.

It is known that N, N'-di-tert-butylethylenediamine can be used as an epoxy curing agent (Virginia Chemical Company, Technical Data,
Bulletin 1100, 95). However, it has been discovered in the present invention that the amine is not suitable for use as a curing agent for blocked isocyanates. Amazingly,
It has been discovered that N, N'-dialkylalkylenediamines having certain definable structures are useful as hardeners for blocked isocyanates. N, N'-
Diisopropylethylenediamine and N, N'-diisobutylethylenediamine are alkylenediamines that can be defined that provide a more stable cured blocked isocyanate product than products obtained from other amine cured blocked isocyanates. ..

[0016]

The N, N'-dialkylalkylenediamines used as curing agents for uncured blocked isocyanates have the general formula:

[0017]

[Chemical 2]

(Wherein x is 2 to 6 and R and R'are alkyl groups), which is one of a group of N, N'-dialkylalkylenediamines. In the present invention, it has been discovered that certain N, N'-dialkylalkylenediamines having the structure shown above possess properties that make them particularly valuable as curing agents.
N, N'-diisopropylethylenediamine and N,
N'-diisobutylethylenediamine is particularly preferred for such applications.

When the N, N'-dialkylalkylenediamine is combined with a blocked isocyanate, it results in a coating composition with the following desirable properties: Improved storage stability 1. Improved properties of thermoset films made from the coatings. (The composition, film properties and storage stability data are shown in Tables I and II).

Products having such desirable properties are useful in many applications such as thermoset isocyanate coatings. Blocked isocyanates
Used when a one-component system is required, the presence of free isocyanate must be ruled out and heat curing is possible. Specific applications would include powder coating, magnet wire coatings and appliance coatings.

Blocked isocyanate coatings which are cured by the method of the present invention are generally isocyanate-terminated prepolymers based on polyester or polyether polyols and aromatic or aliphatic diisocyanates. Good. Phenol, cresol, nonylphenol, caprolactam, oxime, malonate,
Acetoacetate and sodium disulfide blocked isocyanate terminated prepolymers are blocked isocyanates suitable for use in the present invention.

The isocyanate-terminated prepolymer used in the examples contains 10-11% free isocyanate and is an isocyanate-terminated prepolymer from Mobay Chemical Co. blocked with methyl ethyl ketone oxime. Includes Mondur CB-601PMA.

Usually, in the production of blocked isocyanate, the isocyanate prepolymer is charged into a four-neck flask, the blocking agent is added dropwise, and the reaction time is about 30 minutes to 2 minutes.
Allow the temperature to rise gently over time. The material is subsequently diluted with a solvent such as ethylene glycol monoethyl ether acetate.

The novel hardener must be present in the blocked isocyanate in an amount sufficient to react on a stoichiometric basis with the available isocyanate groups of the blocked isocyanate.

Curing must be done under mildly elevated temperatures. Temperatures of 50-150 ° C are used. A preferable temperature range is 100 to 125 ° C.

In the examples, curing is done for 0.5-4 hours or longer. The optimum physical property value is 0.5 to 1.
Obtained using a cure time of 0 hours and a moderately elevated temperature.

The implementation of the novel method according to the invention is apparent from the methods illustrated in Examples 1 and 2. The blocked isocyanates described herein can be converted to N, N'-
The method of curing with dialkylalkylenediamines allows the production of compositions having improved properties over the composition of the art with other curing agents.

The present invention is illustrated by the following non-limiting examples.

Example 1 This example illustrates the preparation of a methyl ethyl ketone oxime blocked isocyanate prepolymer. 1,000 g of Mondur in a 2 liter 4-neck flask equipped with stirrer, thermometer, water condenser, dropping funnel and nitrogen inlet.
CB-601PMA (10-11 of Mobay Chemical Co.
% Isocyanate-terminated prepolymer) containing 100% free isocyanate. Next, methyl ethyl ketone oxime (222.2 g) was added dropwise over 1.1 hours or longer. The temperature rose to a maximum of 68 ° C during that period. After an aging period of 1 hour, this material was added to 135.
Dilute with 9 g of ethylene glycol monoethyl ether acetate. The product had an equivalent weight of 543.6 based on the available isocyanate groups.

Example 2 This example demonstrates the use of N, N'-diisopropylethylenediamine as a curing agent for blocked isocyanate coatings. Also, the improved storage stability and properties of thermoset films produced using the present curing agents are demonstrated to be those produced from JEFFAMINEDR-148 and DER-192 amines (triethylene glycol diamine and tetraethylene glycol diamine). Compared and shown. JEFFAMINE is a trademark name. The composition, film properties and storage stability are shown in Table 1.

[0031]

[Table 1]

Example 3 This example illustrates the use of N, N'-diisobutylethylenediamine as a hardener for the blocked isocyanate coating described in Example 1. In addition, the improved properties of thermoset films made from this material are shown in comparison to those made with JEFFANIN D-400 amine. The composition, film properties and storage stability are shown in Table 2.

[0033]

[Table 2]

Comparative Example This is not suitable as a hardener for blocked isocyanate coatings of N, N'-di-tert-butylethylenediamine (not within the scope claimed by the present invention). Is shown. The composition, details of production and results are shown in Table 3.

[0035]

[Table 3]

In addition, a 5 mil film was placed at 103 ° C. for 6 hours.
Allowed to cure for hours. As a result, this film discolored (yellowed) and cracked when cooled.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor George Philippe Spanza USA, Texas 78757, Austin, Silverleaf Circle 2800 (72) Inventor Wei-Yan Sue United States, Texas 78759, Austin, Knights Bridge 11814

Claims (3)

[Claims] 1. A blocked isocyanate and a compound of formula I: (Wherein x = 2 to 6 and R and R ′ are alkyl groups), N, N′-dialkylalkylenediamine
A coating composition, characterized in that it comprises an amount sufficient to cure the composition. 2. The coating of claim 1, wherein the N, N'-dialkylalkylenediamine is present in an amount sufficient to react on a stoichiometric basis with the available isocyanate groups of the blocked isocyanate coating. Composition. 3. The coating composition according to claim 1, wherein the N, N′-dialkylalkylenediamine is N, N′-diisopropylethylenediamine or N, N′-diisobutylethylenediamine.