JPH0255779A - Coating resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give a coating film excelling in impact resistance, abrasion resistance, water resistance, corrosion resistance, etc., and having a high strength and a high elongation by mixing a specified polyol with a specified polyisocyanate. CONSTITUTION:This composition is prepared by mixing a polyol (A) having at least two, on the average, active hydrogen atoms in the molecule and an absolute viscosity at 25 deg.C <=100 P, which is preferably a compound of a number- average MW<=1000 and a hydroxyl value of 150-350, obtained by transesterifying 20-90 pts.wt. castor oil with 1-25 pts. wt. polyalcohol (e.g., trimethylolpropane) and reacting the product with 5-70 pts. wt. epsilon-caprolactone with a polyisocyanate (B) containing 50-95wt.% liquid diphenylmethane-4,4'-diisocyanate and 5-50wt.% polymethylenepolyphenyl polyisocyanate and having 1-8wt.% carbodiimide bonds and 0-10wt.% urethane bonds in the molecule as essential components in such a ratio that the equivalent ratio of the hydroxyl groups of component A to the isocyanate groups of component B (NCO/OH) is 0.7/1-1.3/1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a new and useful coating resin composition,
More specifically, a specific polyol and a specific liquid diphenylmethane-4,4'- having a carbodiimide bond are used.
A polyisocyanate containing diisocyanate and polymethylene I-riphenyl I-liisocyanate is an essential component, and these two components are contained in a specific ratio. The present invention relates to a resin composition capable of forming a highly thick film that has excellent abrasion resistance, low water absorption, and excellent water resistance and corrosion resistance.

[Prior art and problems to be solved by the invention] Coal tar, asphalt, tar epoxy resin, tar urethane resin, etc. have been used as coating compositions that have excellent corrosion resistance and can be coated thickly. ,
It has been used in tanks, bridges, ships, and other steel structures.

However, many of these coating compositions do not meet today's resource-saving requirements because they also contain organic solvents that are unnecessary for essential film formation, and furthermore, such solvents pose a risk of ignition and explosion. It also has various problems such as volatilization into the atmosphere during the drying process and becoming a source of air pollution. Furthermore, while coal tar is regulated as a Class 2 controlled substance as a specialty agent, the organic solvents mentioned above are stipulated in the Organic Solvent Poisoning Prevention Regulations of the Industrial Safety and Health Act, and their handling will eventually change. There are also safety and health law issues.

In addition, coating compositions such as those described above generally have the disadvantage of being slow to dry and therefore requiring time to handle.

In order to eliminate these various drawbacks, in recent years, efforts have been made to actively develop solvent-free two-component urethane resins.

The simplest form of this type of urethane coating composition is
Examples include two-component systems consisting of castor oil or butadiene polyol and I-lysocyanate, but their cured coatings are sticky and have low hardness, and in addition, they have poor corrosion resistance, so they are not practical. do not have.

As a urethane resin that compensates for such drawbacks, has physical properties and corrosion resistance comparable to those of the conventionally known coating compositions mentioned above, and can also be spray coated, for example, JP-A-57- No. 44678, No. 57-9206
No. 0, No. 59-197466-197469, No. 60
-13855, 60-32857, 60-47
No. 074 and No. 61-64441 and No. 61-
A combination system of castor oil or polybutadiene polyol and polyether polyol has been developed, as disclosed in Publications Nos. 26675 and 26676,
It has been put into practical use.

By the way, since urethane resins containing polyether polyols have a high hygroscopicity, they generally tend to foam when thickly coated, and the urethane resins are hard to cure. Since the coating is immersed in water and easily absorbs water, it tends to deteriorate its adhesion to the metal substrate and cause corrosion of the metal substrate, and in the end, it has satisfactory performance. The current situation is that this is not the case.

On the other hand, the polyisocyanate is generally Irimethylene Iriphenyl polyisocyanate (hereinafter referred to as Crude M
It is abbreviated as DI. ), but this product inevitably has poor compatibility with castor oil and polycitadiene 4-liol, and the resulting film also has an incomplete three-dimensional structure with locally completed molecular chains. It has become the property of

Therefore, urethane coating compositions that have such combinations have insufficient film properties, especially tensile strength, elongation, and tear strength, and, ninth, their compatibility with the various polyols mentioned above. However, calgediimide-modified MDI5i is better than crude MDI.
The reality is that there are even examples of it being used.

However, even this cardidiimide-modified MDI is easily crystallized at low temperatures, so it cannot be used in winter.
In particular, there is a problem with workability outdoors.

[Means for Solving the Problems] Therefore, the present inventors have solved the various problems in the prior art as described above, and as a result of intensive studies to eliminate various drawbacks, have developed a polyol containing an active hydrogen atom. , said 4
It consists of both essential components, polyisocyanate, which has good compatibility with lyol and is resistant to crystallization even at low temperatures, and by mixing and applying these two components, it is possible to achieve high strength and high elongation. To find out a new and useful coating resin composition capable of forming a highly thick film having excellent impact resistance and abrasion resistance, low moisture absorption, and excellent water resistance and corrosion resistance, The present invention has now been completed.

That is, the present invention has an average of 2
a polyol having at least one active hydrogen atom and having an absolute viscosity of 100/Is or less at 25°C; Urethane bond? Liquid diphenylmethane-4,4'-diisocyanate (b-i; hereinafter abbreviated as liquid MDI) containing within a range of 0 to 10% by weight.
and a polyisocyanate (B) containing 50 to 95% by weight of Crude German I (b-2), and a polyisocyanate (B) containing 50 to 95% by weight of Crude Germany I (b-2), and Equivalence ratio (NCO/
It is an object of the present invention to provide a coating resin composition having the above-mentioned properties and comprising OH) in a ratio of 0.7/I N1.3/1.

Here, the above-mentioned compound is one of the essential components constituting the coating resin composition of the present invention. Polyisocyanate (B) is one of the other essential constituents, polyol (A
) is used as a curing agent for liquids with a content of carbodiimide bonds of 1 to 8% by weight and a content of phletane bonds of 0 to 10% by weight, i.e. 50% of t(b-1).
~95 heavy i-tou and Crude MDI (b-2) 5~
50% by weight.

Among them, the above-mentioned liquid component Bb-1) is first processed to reduce the content of carbodiimide bonds by the 1-carbodiimidation method as disclosed in, for example, Japanese Patent Publication No. 7545/1983. A polyhydric alcohol of dihydric or higher valence is added to MDI which has been modified to fall within the range of 1 to 8% by weight, so that the urethane bond content in the resulting liquid is 0 to 10%.
It is obtained by urethanizing at a temperature of about 70°C so that the weight ratio falls within the range of 2 to 6 weight ratio, and is a typical example of such polyhydric alcohols having dihydric or higher valences. Includes ethylene glycol, diethylene glycol, clopylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, l,6-hexanediol, octanediol, hydrogenated bisphenols, cyclohexane dimeta In addition to low molecular weight polyols such as tool, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, diglycerin, diintererythritol or sorbitol, various polyester polyols, polyether polyols, polybutadienebriol, polycargenates Examples include polyols and high molecular polyols such as castor oil-based polyols.

Among these, it is desirable to use low-molecular diols and low-molecular-weight alcohols with dihydric or higher valences, and the dihydric or higher alcohols may be used alone or in combination of two or more types.

Next, the crude MDI (b-2) is represented by the formula, and a representative example of a commercially available product is "Parnock 9-409J (Dainippon Ink & Chemicals Product ■)"
and “Millione” MRJ (Japan Polyurethane Industry ■
products] etc.

The ratio of the above-mentioned components (b-1) and (b-2) is not uniform because it is determined by conditions such as the temperature and required film properties when using them. , generally (b-1)/(b-2) -50/9
5 to 5015, preferably this ratio is 70/
The range used is 30 to 90/10.
It is suitable because it can achieve a /4 ratio in terms of film properties and workability.

(b-1) When the proportion of the component increases, physical properties such as tensile strength and elongation of the film improve, but it tends to crystallize in the low temperature region of about 10℃ or less, and as a result, workability deteriorates. On the other hand, when the proportion of component (b-2) increases, it does not crystallize even at low temperatures of about 0°C and has excellent workability, but the physical properties of the film tend to deteriorate.
Therefore, neither is preferable.

In addition, the diimide bond content of component (b-i) is suitably within the range of 1 to 8% by weight, preferably 2 to 5% by weight, and if it is less than 1% by weight, it will become liquid at room temperature. On the other hand, if it exceeds 8 weight range, the viscosity will inevitably increase and it will be difficult to further convert it into urethane, which is not preferable.

Further, the urethane bond content of the component (b-x) is suitably within the range of 0 to 10% by weight, preferably 2 to 6% by weight. As the amount of urethane bonds increases, the compatibility with polyols and the physical properties of the film improve, but if it exceeds 10% by weight, the viscosity inevitably increases and workability deteriorates, which is undesirable.

The polyol (A), which is the other essential component constituting the composition of the present invention, may be any of various conventionally known compounds as long as it has an average of 2 or more active hydrogen atoms in the molecule. can be used without any problem, but the most typical ones include alkyds, polyesters, polyethers, acrylics, polybutadienes, and polyesters that have two or more active hydrogen atoms such as hydroxyl groups or amino groups in the molecule. In the ether, in it,
It is appropriate to use a polyol with an absolute viscosity of 100 poise or less at 25°C, preferably 20 to 90 parts by weight of castor oil (Melon-1) and 1 to 25 parts by weight of a dihydric or higher polyhydric alcohol ( a-2) and then transesterified with 5 to 70 parts by weight of C-caprolactone (a-2).
3) The number average molecular weight is 1, as obtained by reacting 2
000 or less, and the hydroxyl value is 150 to 350,
It is a relatively low molecular weight polyol.

Here, a polyhydric alcohol (a
-2) as mentioned above, liquid MDI (b-1
) are used in the preparation of
Used as is.

First, castor oil (a-1) and this polyhydric alcohol (a-2) are transesterified at 200 to 250°C in the presence of a basic catalyst, and then g-caprolactone is opened at about 200°C. A cycloaddition reaction may be performed.

At this time, the appropriate amount of castor oil to be used is 20 to 90 parts by weight, preferably 35 to 65 parts by weight, and 201i
If the amount is less than 901!, the viscosity and crystallinity of the resin will increase, resulting in decreased storage stability and loss of smoothness and uniformity of the cured film.On the other hand, 901! If the amount is exceeded, the properties will approach those of castor oil itself, resulting in a decrease in film hardness and corrosion resistance.

In addition, the amount of polyhydric alcohol (a-2) used is 1-
A suitable amount is 25 parts by weight, preferably 10 to 20 parts by weight. If it is less than 1 part by weight, the crosslinking density of the film will inevitably decrease, and the film hardness, water resistance, corrosion resistance, etc. On the other hand, if it exceeds 25 parts by weight, the molecular weight between crosslinks of the membrane decreases and the membrane becomes brittle, resulting in a decrease in impact resistance, adhesion, etc.

Furthermore, 6-caprolactone is used for the purpose of improving the compatibility of polyol (A) with polyisocyanate (B) and imparting flexibility to a cured film, but the amount of e-caprolactone used is 5 to 70 parts by weight,
Preferably, it is within the range of 15 to 55 parts by weight], 5
If it is less than 70 parts by weight, the effects that meet the above-mentioned intended use will be reduced, while if it exceeds 70 parts by weight, crystallization of the polyol obtained and a decrease in film hardness will inevitably occur.

In this way, when preparing a specific polyol by reacting ε-caprolactone with the transesterification product of castor oil and polyhydric alcohol, the ratio of each raw material is (a-1): (a -2) :(a-3)
-(20-90): (1-25): (5-70).

The number average molecular weight of the specific broken ol thus obtained is suitably within the range of 1,000 or less, preferably 500 to 800, and the hydroxyl value of the polyol is 150 to 350, preferably 200 to 300. It is appropriate to fall within the following range. If the number average molecular weight exceeds 1,000 and becomes excessively large, workability during coating and painting will deteriorate, and if the hydroxyl value is less than 150, the crosslinking density of the film will inevitably decrease. As the value becomes lower, the film strength also decreases, and the corrosion resistance tends to deteriorate.On the other hand, if it exceeds 350, the impact resistance and bending properties of the film decrease. , all of which become undesirable.

The equivalent ratio (NCO/OH) between the active hydrogen atoms of the polyol, especially the hydroxyl groups, and the isocyanate groups of the polyisocyanate (B) is 0.7/1~! ,
3/1. Preferably, it is within the range of 0.9/1 to 1.1/1; if it is less than 0□7, the curing will inevitably be insufficient, and if it exceeds 1.3, the obtained The coating is brittle and the physical properties are significantly deteriorated, and in either case, corrosion resistance is adversely affected, which is not preferable.

Moreover, the JI of the cured product obtained from the coating composition of the present invention
The water absorption rate according to S K 7209 is 1 weight or less, preferably 0.5! It is appropriate that the value is within the range of 1 weight or less, and if this value exceeds 1 weight factor, it is inevitable that
This becomes undesirable because the film swells, its adhesion to the material deteriorates, it corrodes, and it becomes flat.

The thus obtained coating resin composition of the present invention may further contain curing catalysts such as organometallic compounds such as digtyltin diocrate or dibutyltin diacetate and various amines; azo type, copper phthalocyanine type, and valve. Organic or inorganic coloring pigments such as yellow lead, titanium oxide, zinc white or carmen black; preventive agents such as lead red, lead white, basic chromate, basic sulfate, zinc chromate, zinc dust or MIO. Rust pigments: Precipitated calcium carbonate, precipitated palicum sulfate, clay silica, extender pigments such as talc or mica are appropriately blended, as well as leveling agents, moisture absorbers, or silane-based or titanate-based coupling agents. Various auxiliary agents such as the following may also be added as necessary.

Furthermore, plasticizer components such as dioctyl phthalate, asphalt, or tar; various resins such as xylene resins or vinyl resins;
It can be used as long as it does not cause any damage.

The composition of the present invention can be applied by brush application, or by spray application. Of course, when the viscosity is high, it is preferable to heat it to about 60°C to reduce the viscosity and spray paint it. [Effects of the Invention] The coating resin composition of the present invention has the following characteristics: As one,
An active hydrogen atom-containing polyol (A) and the polyol (
A) A special polyisocyanate which has good compatibility with K and excellent low temperature stability (B). By reaction with polyol,
It is said that it can form a thick film that has high strength and elongation, has excellent impact resistance and abrasion resistance, and has low moisture absorption and excellent water resistance and corrosion resistance. It is useful and therefore particularly suitable for corrosion protection, such as in concrete and steel structures.

〔Example〕

Next, the present invention will be specifically explained with reference to Reference Examples, Examples, and Comparative Examples. In the following, all parts and parts are based on weight unless otherwise specified.

Reference Example 1 (Example of preparation of active hydrogen atom-containing preol (A)) 42 parts of castor oil and 1 part of trimethylolgulonone
2 parts in the presence of 0.02 part of lithium hydroxide, 25
After carrying out the transesterification reaction at 0°C for 1 hour, further 8
- 46 parts of cabrocton was reacted in the presence of 50 ppm of tetrainoglovir titanate at 200°C for 5 hours to obtain a number average molecular weight of 740 and a hydroxyl value of 220.
A target product was obtained in which the absolute viscosity at 25° C. (the same applies hereinafter) was 9/Is.

Reference Example 2 (same as above) In the same manner as in Reference Example 1, 72 parts of castor oil and 11 parts of intererythritol were transesterified, and then 17 parts of C-caprolactone was also reacted, resulting in a number average molecular weight of 650. A target product having a hydroxyl value of 290 and a viscosity of 14 voids was obtained.

Reference Example 3 (same as above) In the same manner as in Reference Example 1, 42 parts of castor oil, 4 parts of 1,4-butanediol, and 6 parts of hyintererythritol were subjected to transesterification reaction, and then 48 parts of e-cablocktone was transesterified. A target product having a number average molecular weight of 740, a hydroxyl value of 215, and a viscosity of 9 poise was obtained.

Reference Example 4 (same as above) In the same manner as in Reference Example 1, 34 parts of castor oil, 2 parts of 1,4-butanediol, and 9 parts of hyintererythritol were transesterified, and then 55 parts of 8-cablocktone was transesterified. A target product having a number average molecular weight of 910, a hydroxyl value of 230, and a viscosity of 1573e was obtained by reacting 60 parts of castor oil in the same manner as in Reference Example 1. Oh hydrimethylol! 17 parts of Lonoyan was transesterified,
Next, 23 parts of I-cablocktone was also reacted to obtain a target product with a number average molecular weight of 510, a hydroxyl value of 300, and a viscosity of 1111e. Preparation example of diisocyanate (B)] 98 parts of diphenylmethane-4,4'-diisocyanate (MDI) was added to 1-ethyl-3-methyl-3-phosphine-
3 at 90°C in the presence of 0.003 part of 1-oxide.
After a time reaction, the carbodiimide bond content was 2% and the isocyanate group content (NCO content) was 28%.
Cal 96 obtained diimide modification immediately ■9. This one is 1
On the 4th day at a temperature of 0°C, a white sedimentation sound was produced.

Next, 2 parts of 1,4-butanediol was added to the diimide-modified MDI and reacted at 70°C for 1 hour to obtain a urethane bond content of 3- and an NCO content of 2-.
Six liquids immediately! I got it. Hereinafter, this will be referred to as liquid MDI (b
This product, abbreviated as -1-1), had been improved to the point where a white precipitate was produced for the first time after about one week at a temperature of 10°C.

After that, 80 parts of this liquid my(b-t-1) was cold blended with 20 parts of crude MDI0, and N
A target product with a GO content of about 27 was obtained. The one with
It showed stability for more than 7 days even at a temperature of 5°C.

Reference Example 7 (same as above) Immediately add crude to 60 parts of liquid mass r (b-1-1)! 04
By cold blending 0 parts, a target product with an NCO content of 28 was obtained. It was confirmed that this product was stable for 7 days or more even at a temperature of 0°C.

Reference example 8 (same as above) Nine cals obtained in reference example 6? Diimide modification immediately! 6 parts of diglopylene glycol were reacted with 94 parts of the liquid at 70°C to obtain a liquid MDI having a carbodiimide bond content of 7x2x, a urethane bond content of 5x, and an NCO content of 23x. Ta. Hereinafter, this will be referred to as liquid MDI (b-1
This product, abbreviated as -2), is stable at a temperature of 10°C, but a white precipitate formed in just one day at 5°C.

Next, 90 parts of this liquid Mo1 (b-x-2) was cold-blended with 10 parts of Klutoli (2) to obtain a target product with an NCO content of 24. This product was confirmed to be stable for 7 days or more even at 5°C.

Reference Example 9 (same as above) Add 60 parts of liquid instant I (b-1-2) to Klutoli! 4
0 parts were cold blended to obtain the desired product with an NCO content of 26%. It was confirmed that this product had stability for 7 days or more even at 0°C.Reference Example 10 (same as above) In the same manner as Reference Example 6, Cal had a diimide bond content of 4% and an NCO 98 parts of calzadiimide-modified MDI with a content of 261 was obtained. Then add 1.4-
A liquid MDI with a urethane bond content of 3 and an NGO content of 24 is produced by reacting 2 parts of f-tanediol.
(b-1-3) was obtained. This product formed a white precipitate after about one week at 10°C.

Thereafter, 30 parts of crude MDI was cold blended with 70 parts of this liquid sor(b-x-3), and NC
A target product with an O content of 26% was obtained. This one is 0℃
It was confirmed that it has stability for 7 days or more even at different temperatures.

Reference Example 11 (same as above) The carbodiimide bond obtained in the same manner as Reference Example 6 is 4
By reacting 2 parts of octanediol with 98 parts of carbodiimide-modified MDI having an NGO content of 26%, a liquid MDI having a urethane bond content of 3 parts and an NGO content of 24% (b -1-4) was obtained. This product was stable only at 10°C, but a white precipitate formed in just one day at 0°C. Next, 40 parts of crude MDI was cold blended with 60 parts of this liquid slurry, and N
A target product with a CO content of 27% was obtained. This one is 0
It was confirmed that it had stability for 7 days or more even at ℃.

Reference Example 12 (Preparation Example of Control Polyisocyanate) In the same manner as Reference Example 6, the carbodiimide bond content was 1.
1. I was disappointed with the carbodiimide-modified MDI for comparison, but this one has a high viscosity even at a high temperature of 70°C.
Furthermore, it was confirmed that it was difficult to convert it into urethane.

Reference Example 13 (same as above) In the same manner as Reference Example 6, a control carbodiimide-modified MDI 'i with a carbodiimide bond content of 0.5
However, this product exhibited white crystals at room temperature. Next, 3 parts of 1,4-butanediol was added to 97 parts of this control MDI to cause a urethanization reaction, and an O that exhibited white crystals at room temperature was obtained. Reference Example 14 (Same as above) Reference Example When 8 parts of 1,4-butanediol was added to 92 parts of the carbodiimide-modified MDI obtained in step 6 and a urethane reaction was performed, a control polyisocyanate with a urethane bond content of 12 was obtained. However, this product was solid at room temperature.

Reference Example 15 (same as above) 8 parts of crude MDI to 20 parts of liquid instant r(b-t-x)
0St - cold blended, NGO content is 30
An excellent control polyisocyanate was obtained. It was confirmed that this product is stable even at a low temperature of 0°C.

Examples 1 to 9 and Comparative Example 1.2 Polyols (A-1) to (A-
5) and various commercially available polyols, and I reinocyanates (B-1) to (B-1) obtained in Reference Examples 6 to 11 and 15.
B-6) and (B'-1) were blended at the composition ratio shown in Table 3, especially at the NGO10H ratio, and then film-formed and heated at a temperature of 23±2°C and a relative Humidity 50±
The physical properties and corrosion resistance of each film obtained by curing for 7 days under conditions of 5% f- Liver value review friend. The results are summarized in the same table.

Footnotes to Table 3 1) "Burnock D-220J Dainippon Ink & Chemicals @ Hibi's polyester polyol 2) rNicalite H-470J ... Acrylic polyol "R-45HT" manufactured by Nippon Carbide Industries ■ Idemitsu Oil Polybutadiene polyol manufactured by Kagaku ■ "Nukol BA-P3J Nobori ether polyol manufactured by Nippon Nyukazai ■ 5) Compliant with JIS K7113 6) On a sandblasted steel plate with a thickness of 1.6 mm,
Using a sample coated with a film thickness of 1 fl, JIS K5400
The film thickness is 1.6 fl on a sandblasted steel plate with a thickness of 1.6 fl.
JI8K 7 using a sample coated so that fi
209 compliant JIS K5664 compliant

Claims (1)

[Scope of Claims] 1. (A) a polyol having an average of two or more active hydrogen atoms in the molecule and having an absolute viscosity of 100 poise or less at 25°C, and (B) a carbodiimide bond in the molecule. Contains 1 to 8% by weight, and 0 to 10% by weight of urethane bonds
Liquid diphenylmethane-4,4' containing within the range
- 50 to 95% by weight of diisocyanate (b-1) and polymethylene polyphenyl polyisocyanate (b-2);
) is an essential component, and the equivalent ratio (NCO/OH) of the hydroxyl groups of the former polyol (A) and the isocyanate groups of the latter polyisocyanate (B) is 0.7/ A coating resin composition comprising a ratio of 1 to 1.3/1. 2. The polyol (A) is obtained by transesterifying 20 to 90 parts by weight of castor oil (a-1) and 1 to 25 parts by weight of a dihydric or higher polyhydric alcohol (a-2), and then transesterifying this. 5 to 70 parts by weight of ε-caprolactone (a-3)
2. The coating resin composition according to claim 1, which is a compound obtained by reacting a compound having a number average molecular weight of 1,000 or less and a hydroxyl value of 150 to 350. 3. JISK7 of the cured product obtained from the coating composition
2. The resin composition for coating according to claim 1, having a water absorption rate of 1% by weight or less according to 209.