JPH02677A - One-pack urethane coating - Google Patents

Abstract

PURPOSE:To obtain the subject coating prevented from undergoing thermal yellowing and cratering in a high film thickness, lowered in a curing temperature in baking and improved in storage stability by mixing a urethane prepolymer having blocked terminal NCO groups with a specified curing agent. CONSTITUTION:An NCO group-terminated prepolymer obtained by reacting an organic polyisocyanate with a polyhydroxy compound at 60-90 deg.C for 3-6hr is reacted with a blocking agent at 70-150 deg.C for 4-10hr in the presence of, optionally, a catalyst to obtain a urethane prepolymer (A) having blocked terminal NCO groups. Separately, an addition reaction of an alkylenediamine with an alkylene oxide is performed to obtain a curing agent (B) comprising a polyfunctional polyol of the formula (wherein n and m are each 1-6). Component A is mixed with component B in an equivalent ratio of component B to component A of (7-15)/10 to obtain the subject coating. Said coating is applied to a substrate such as a wire and baked at 90 deg.C, desirably, 100-170 deg.C for at most 120min, desirably, at most 60min.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molded urethane paint, and more specifically, a prepolymer in which terminal isocyanate groups are blocked and temporarily inactivated (hereinafter referred to as block prepolymer). Baking comprising hardeners is relevant to mold-liquid urethane based paints.

Conventionally, one-component polyurethane paints have been produced by, for example, reacting the raw material incyanate with a blocking agent, or reacting various polyols with an excess of in7anate to form a prepolymer of terminal isocyanates, which is then reacted with a blocking agent. A one-component coating composition that is stable at room temperature is formed by blending a polyol, polyamine, etc. as a curing agent with a curing agent. It is well known that this method is based on a method of regenerating the t group.

However, one-component paints made from blocked isocyanates have a coating limit of 1 good. The problem is that the thickness of the armpit is low.

On the other hand, liquid-type paints made from block prepolymers are superior to those made from block isocyanates in that it is possible to adjust the isocyanate content through polymerization, and the coating film can be made into any desired shape by selecting the partner polyol. Since then, baking has been widely used as a paint.

As a typical example of a prepolymer containing 1 mole of trimethylolpropane (hereinafter referred to as TMP) and 3 moles of tolylene diisocyanate (hereinafter referred to as TDI), 3 moles of phenol is added to a prepolymer of 1 mole of trimethylolpropane (hereinafter referred to as TMP). Stable (manufactured by Nippon Polyurethane Industries) is widely used as a coating material.

Recently, there has been a demand for blocking agents with less toxicity and odor, and for this purpose, block prepolymers using alcohols, lactams, etc. are being researched and developed. However, block prepolymers using these blocking agents have a high dissociation temperature of 170'O to 250°C.
If a grade or secondary amine is selected, it may cause skin damage to the human body9, be difficult to handle due to its hygroscopicity, have low heat resistance of the cured coating, and have poor flexibility, adhesion, etc. I haven't been able to get anything that I'm satisfied with either.

In the case of aromatic amines, they are often solid or viscous liquid at room temperature and are inconvenient to handle, have lower low-temperature M separation ability than aliphatic amines, and have drawbacks such as sometimes yellowing when baked.

In addition, acid amides synthesized by the reaction of fatty acids and aliphatic polyamines generally have low vapor pressure and, as a result, are low in toxicity, but on the other hand, the range of selectivity of the solvent used for dilution is narrow, Bath additives cannot be used, and the acid amide itself is colored, which limits its uses and has drawbacks such as poor storage stability.

In addition, as an example of cycloaliphatic polyamine, JP-A-48
-16949 as a curing agent 3-37-cymethyl-4-
Although the use of 4'-diamino-dicyclohexylmethane is disclosed, Comparative Example 4. As seen in the above, there are problems in terms of hardenability and the limit of the coating film, and furthermore, there are disadvantages such as baking tends to cause yellowing due to heat, and the coating film is hard and brittle. Not obtained.

Therefore, as a result of intensive research, the present inventors have found that by combining a specific amine-based curing agent with a block prepolymer, it has good storage stability, has a low curing temperature during baking, and is free from thermal yellowing and high film thickness. We have discovered a molded urethane paint that does not have wrinkles and have arrived at the present invention.

That is, the present invention has 11. A one-component urethane paint characterized by using a urethane prepolymer with blocked terminal incyanate groups and a curing agent as described in (1) below as raw materials for its production.

(1) A polyfunctional polyol represented by the following general formula, which is obtained by adding alkylene oxide to alkylene diamine.

CH, CH3 CH.

CH.

However, in the formula, n, m: = 1~6° It is related to.

The blocked prepolymer that can be used in the present invention can be obtained by reacting an organic polyisocyanate with a polyhydroxy compound to obtain an isocyanate group-terminated prepolymer, and reacting the prepolymer with a blocking agent.

Organic polyisocyanates that can be used in the present invention include:
Any aliphatic, aromatic, cycloaliphatic, araliphatic polyinsyanate may be used, such as hexamethylene diinocyanate, trimethylhexamethylene diinocyanate, isophoro/diisocyanate, lysine diisocyanate TDI, 4-4'- Examples include diphenylmethane diisocyanate (hereinafter referred to as MDI), polyphenylmethane polyisocyanate, quinrylene diisocyanate hydrogenated TDI, hydrogenated MDl, etc., and these polyincyanates and water, ethylene glycol, diethylene glycol,! -3-phthelene glycol (hereinafter 1-3-B
G), dipropylene glycol (hereinafter referred to as DPG), neopentyl glycol, glycerin, TMP,
Inphorondiamine is obtained by reaction with a low-molecular polyfunctional compound containing an active hydrogen atom (hereinafter referred to as a low-molecular polyfunctional substance) such as hexamethylene diamine.

Examples Eva, Coronate L (manufactured by Nippon Polyurethane Industries, trade name, NGO content 13.2%), Coronate) 1-IL (
Manufactured by Nippon Polyurethane Industries, trade name, NCO content 12.
8), HL-100 (manufactured by Nippon Polyurethane Industries, trade name, NCO content 17.1), etc.

Furthermore, polyisocyanates containing belet bonds, allophanate bonds, incyanurate bonds, carbodiimide bodies, etc. in the molecule are also included in this range, and in the present invention, one or a mixture of two or more of these organic polyisocyanates is included. can be used.

Examples of polyhydroxy compounds that can be used as partner substances for organic polyisocyanates for prepolymer preparation include polyester polyols and polyether polyols with a molecular weight of 150 to 150, o o o and a hydroxyl value of 3.
0 to 550, castor oil and its derivatives with a molecular weight of 9
00 to 2,000 and a hydroxyl value of 160 to 370, acrylic polyol with a molecular weight of 1,000 to 10,000 and a hydroxyl value of 15 to 100, polybutadiene polyol with a molecular weight of 1,000 to 3,000 and a hydroxyl value 40-1
10, butyral resin, epoxy resin, etc. may be mentioned, and one or a mixture of two or more of these resins can be used.

Examples of polyester polyols include ethylene glycol, diethylene glycol, tri-r-ethylene glycol, 1-2-propylene glycol, trimethylene glycol, 1-3 or 1-4 butylene glycol, hexamethylene glycol, decamethylene glycol, glycerin, 'rMP , a monomolecular compound having two or more hydroxyl groups such as pentaerythritol, sorbitol, etc.
seeds or 241 or more and adipic acid, succinic acid, malonic acid,
Monomolecular metals having two carboxyl groups such as maleic acid, tartaric acid, pimelic acid, sebacic acid, phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, etc., 01
Honya ε- obtained by condensation reaction with a species or two or more species
Lactone esters produced by ring-opening polymerization such as caprolactone and ε-valerolactone are used.

Examples of polyether polyols include ethylene glycol, globylene glycol, diethylene glycol, 1-
3-BG, TMP, glycerin, hexanetriol,
Those obtained by addition polymerization of one or more polyhydric alcohols such as pentaerythritol and sorbitol with alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide are used.

Furthermore, the above-mentioned low-molecular polyfunctional substance (used in the synthesis of isocyanate-terminated greborimer of organic polyinthate) was used as a chain extender during prepolymer preparation.
Furthermore, a low-molecular polyfunctional substance other than Mercury can be used in combination as a polyhydroxy compound.

These prepolymers terminated with isonic atom groups can be prepared by using an organic polyisocyanate and a polyhydroxy compound alone or in combination with a low-molecular polyfunctional substance other than Mercury, at a normal urethanization reaction temperature of 60 to 90°C. It can be produced by reacting for 6 hours.

At this time, the NCO of the isocyanate curtain-terminated gleborimer
It is preferable to set the preparation conditions so that the content is in the range of 3 to 10 inches. This is to keep the effective NCO content of the block prepolymer from 2 to 8%.If the effective NCO content of the block prepolymer is less than 2%, the viscosity will increase, workability, and compatibility with other resins will decrease. As a result, as the amount of blocking agent to be added increases as the amount exceeds 8%, it becomes difficult to obtain a high film thickness due to the lowering of the edge limit due to scattering of the blocking agent during baking. It is.

A catalyst can be added to these incyanate group-terminated prepolymer synthesis reactions as necessary.

The catalyst is usually dibutyltin dilaurate (DB
TDL), tin octenoate, naphthi/calcium acid, and other known materials are used in an amount of 0.001 to 1.0 weight relative to the resin content.

The block prepolymer used in the present invention can be produced by reacting an incyanate group-terminated prepolymer and a blocking agent at 70 to 150'C for 4 to 10 hours by a known method.

Blocking agents used in Flockfre polymers include known alcohols such as methanol, ethanol, and n-butanol, phenols such as phenol and cresol, hydroxyl-functional ethers such as methyl cellosolve and methyl cellosolve, ethyl lactate, and lactic acid. Hydroxyl group-containing esters such as amyl, active methylenes such as diethyl malonate, methyl acetoacetate, mercaptans such as butyl mercaptan, pequinlumercabutane, acid amides such as acetanilide, acrylamide, timer acid amide, imidazole, 2-ethyl imidazoles such as imidazole,
Oximes such as methyl ethyl ketoxime and acetoxime, acid imides such as succinimide and phthalic acid imide, 6-caprolactam dia-7ton alcohol, and the like can be used.

For this reaction, a catalyst of 0.001 to 1.0
The catalyst that can be used in a heavy ffi% range may be the catalyst used in the synthesis reaction of the isocyanate group-terminated prepolymer described above, or other known catalysts that are commonly used for this type of purpose.

In this case, the effective NGO content of the block prepolymer is
It is preferable to adjust the Vi to 2 to 8%, preferably 2.5 to 7%, based on the resin content.

In the synthesis of these isocyanate group-terminated prepolymers and blocks thereof, a bath agent may be used as necessary. Examples of preferred solvents include ester-based acetic acid ethyl ester (hereinafter referred to as acetic acid), methyl cellosolve acetate, acetic acid cellosolve acetate (hereinafter referred to as acetic acid), aromatic toluene and xylene, and ketone-based methyl in butyl ketone. Or mineral spirits etc. are mentioned.

As the specific amine curing agent in the present invention, the following (1) represented by the general formula described above can be used.

(As for 11, examples of polyfunctional polyols include N-N-N'/N'-tetrakis(2-hydroxinglovir)ethylenediamine (trade name: Quadrol) manufactured by Asahi City Kakogyo, EDP-450, BDP- There is 650 etc.

Further, the specific curing agent of the present invention and known glycols, hydroxyl group-containing polyols, etc. can be used in combination for this purpose.

The amount of the curing agent to be used is such that the equivalent ratio of curing agent to Flockfre polymer is 7/10 to 15/lo, particularly preferably 8/10 to 1.
2/10 is appropriate.

When the equivalent ratio is smaller than 7/10, the coating film tends to foam, and when it is larger than 15/10, the coating film tends to be difficult to cure.

In the one-component urethane paint according to the present invention, colorants, thickeners, bath agents, 'oJ plastics, etc. can all be applied, and various additives, thickeners, etc. can be mixed as necessary. Equipment (three-roll, bot mill, sand grind mill, etc.)
It can be made into a paint using.

The baking of the paint prepared by K as above is 90°.
It can be carried out at a relatively low temperature of C or above, preferably 100 to 170°C, and usually within 120 minutes, particularly preferably within 60 minutes.

In addition, it has characteristics such as not causing wrinkles even when it is applied to a high film thickness of 100μ or more in one coat and cured, and does not cause yellowing due to heating, making it suitable as a chipping prevention paint for other metals. It can be used in a wide range of applications, such as pre-coating, AM coatings, and plastic coatings.

The present invention will be explained below with reference to examples. In the examples, parts and parts are by weight unless otherwise specified.

Examples, 1-2 In a reactor equipped with a thermometer, a reflux condenser, a nitrogen seal tube, and a stirrer, the amounts of organic polyisomers shown in Table 1 were added, optionally in the presence of a solvent. The temperature was raised to 45°C without stirring, and at the same temperature, a predetermined amount of Polio-A/ was added dropwise to react under the conditions shown in Table 1 to form an incyanate curtain-terminated polymer. Next, a predetermined amount of blocking agent shown in Table 2 was added to the prepolymer and reacted under the conditions shown in the table to obtain a block prepolymer.

Next, a curing agent was added to the blocked isocyanate in the proportions shown in Table 2 and mixed to obtain a one-component paint.

Comparative Examples, 1, 2 The block prepolymer was synthesized and the molding paint was synthesized using the formulations shown in Table 3 and in the same manner as in the examples. Manufactured by Polyurethane Industries, product name: TDI2)
Product name Polymeric MD
I3) Manufactured by Sanyo Chemical Industries, Ltd. Product name Polyether molecular weight 6
00 4) Polyether molecular weight 1
000 5) Polyether diol table manufactured by Asahi Denka Kogyo.

5) Manufactured by Mitsui Toatsu Chemical Industry Co., Ltd. 6) Manufactured by Ube Industries, Ltd. Product name: Manufactured by Toagosei Chemical Industry Co., Ltd., product name: Methyl ethyl ketoxime 1) Has7 Company m (Product name) 3-amino-1-
Cyclohexylaminopropane storage stability test Examples 1 and 2, Comparative Examples 1 and 2 one-component paints were soomd
The mixture was placed in a glass bottle, sealed tightly, and stored at 45°C for 12 months, and tested for appearance, NCO content, viscosity, etc., and comprehensively judged. The results are shown in Table 4.

Testing of mold resistance and coating film underside limit The one-component paints of Examples 1 and 2 and Comparative Examples 1 and 2 had a solid content of 70
Dilute with seven drops of vinegar and spray with air (pressure 3.0 K).
y/crtt) and film thickness 100.150.200.25
Tin plate (100 tomo x 3oomx x o4mx) so that it is 0.300゜350.400.5oo (Jl)
K m cloth coat Nc + coat! ll [li did.

Also, tin plate (100m x 300m1+ x 0.4m
1c) was applied to the same film thickness as above and was left at room temperature for 5 minutes, then cured at 140°C for 30 minutes, and the edge limit of the coating was tested. The results are shown in Table 4.

JR-702 (manufactured by Hotarukuni Kako Co., Ltd.,
(trade name, titanium oxide) was added and mixed using Daysilver, and the particle size was 40 to 45 using a grind gauge using a three-roll roll.
Distributed so that μ.

These paints were prepared with a mixed solvent of vinegar: xylene = x: x (weight ratio) to an application solid of 65%,
450μ with air spray (pressure 2.5 Ky/cal)
(wet film thickness) on a tin plate (100mm x
300 rhymes x 0.4 dragons) and left at room temperature for 5 minutes.
A test piece was prepared by curing at 40"C for 130 minutes in an open setting.

The test results are shown in Table 4.

Margin below

Claims (1)

[Scope of Claims] 1. A one-component urethane paint, characterized in that a urethane prepolymer whose terminal isocyanate groups are blocked and a curing agent comprising the following (1) are used as raw materials for its production. (1) Multifunctional polyol represented by the general formula below, which is made by adding alkylene oxide to alkylene diamine ▲ There are numerical formulas, chemical formulas, tables, etc. ▼ However, in the formula, n and m = 1 to 6