JPS63264676A - Cement pipe coated with solvent-free two-component urethane paint composition - Google Patents

Abstract

PURPOSE:To obtain a coated cement pipe excellent in impact resistance, chemical resistance, salt water resistance and corrosion resistance, by coating a cement pipe with a solventless two-component urethane coating composition essentially consisting of a specified polyol and a polyisocyanate. CONSTITUTION:A cement pipe coated with a solventless two-component urethane coating composition essentially consisting of a polyol (A), number-average MW <=1,000 and hydroxyl number of 150-350, obtained by reacting 100pts.wt. polyol obtained by reacting 50-95wt.% castor oil (a) with 1-30wt.% dihydric alcohol (b) and 3-30wt.% at least trihydric alcohol (c) in amount to give a total of 100wt.% with 3-30pts.wt. epsilon-caprolactone (d) and a polyisocyanate (B) and having an (NCO/OH) ratio of (0.6-1.6)/1.0. Said coated cement pipe has a film thickness of 0.1 to several mm and excels in impact resistance, chemical resistance, salt water resistance and corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cement pipe coated with a solvent-free two-component urethane coating composition for impact resistance, chemical resistance, salt water resistance and corrosion resistance.

[Prior Art] The inner surfaces of cement I pipes used for water and sewage pipes and industrial water pipes are generally not anticorrosive. In recent years, corrosion due to acids caused by hydrogen sulfide has become a problem, especially in gravity-flow cement pipes used for sewer pipes. As a countermeasure, coating with anticorrosive paint such as coal tar, asphalt, tar epoxy resin paint, tar urethane resin paint, etc. is considered. However, many of these coating materials contain organic solvents, which pose a risk of ignition and explosion, and the organic solvents scatter into the atmosphere during the drying process, thus becoming a source of air pollution.

Coal tar-based substances are specified as Class 2 controlled substances for specialized use, and solvents containing solvents are specified in the Organic Solvent Poisoning Prevention Regulations of the Industrial Safety and Health Act. There is a problem above.

Moreover, these paints generally dry slowly and take a long time to handle.

In recent years, solvent-free two-component urethane resin paints have been developed to improve these drawbacks. The simplest urethane resin composition is a two-component system of castor oil and polyisocyanate, but in this case, the hardness of the cured coating is low;
It also has poor corrosion resistance and is not practical. A system that uses castor oil in combination with polyether polyol has been developed and put into practical use as a urethane resin paint that compensates for this drawback and has physical properties and corrosion resistance equivalent to those of the previously known paints, and can be sprayed ( Japanese Unexamined Patent Publication No. 1974-197466, 60-
13855, 60-32857.60-47074.6
1-26675).

[Problems to be Solved by the Invention] By the way, urethane resin coatings containing polyether polyols generally tend to foam when thickly coated due to the high hygroscopicity of the polyether polyols, and the cured coating film cannot be immersed in water. If it does, it will easily absorb water, cause deterioration of adhesion to the cement base, and corrosion, resulting in unsatisfactory performance. On the other hand, it has also been proposed to use polybutadiene diol instead of polyether (Japanese Patent Laid-Open No. 59-19
7467-9) Since polybutadiene diol is difunctional, it has the drawbacks that the resulting coating film has a low crosslinking density, is easily swollen by water, and has a high resin viscosity, making spray coating difficult.

In order to solve the above-mentioned problems, the present invention provides a solvent-free two-component urethane coating composition that has impact resistance, chemical resistance, water resistance, and corrosion resistance that are equivalent to or higher than conventionally known coatings, and that is difficult to foam during coating. The object of the present invention is to provide a cement pipe coated with (A) (a) 50 to 95% castor oil.
, (b) 1 to 30% by weight of dihydric alcohol, and (c) 3 to 30% by weight of polyhydric alcohol of trihydric or higher valence, 100% by weight of a polyol obtained by reacting such that the total of each component is 100% by weight. 3 to 30 parts by weight of (d) ε-caprolactone with a number average molecular weight of 1
000 or less, a polyol with a hydroxyl value of 150 to 350, and (B) polyisocyanate as essential components, and the equivalent ratio of the isocyanate group to the hydroxyl group of the polyol (NCO/OH
) is (0.6 to 1.6)/1.0, and is summarized as a cement pipe coated with a solvent-free two-component urethane coating composition, which does not cause the above-mentioned safety and health problems.
In addition, it is possible to provide a cement pipe with a strong anti-corrosion coating that does not cause foaming.

Used in the present invention (A>constituent component of polyol (
The dihydric alcohol of component b) includes ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1.
4-butanediol, neopentyl glycol, 1.6
-Hexanediol.

Examples include octanediol, 1,2-hydroxystearyl alcohol, hydrogenated bisphenol A, and cyclohexane dimetatool. (c) Component trihydric or higher polyhydric alcohol includes glycerin.

Trimethylol ethane, trimethylol propane.

Examples include pentaerythritol, diglycerin, dipentaerythritol, and sorbyl.

Further, oxycarboxylic acids such as dimethylolpropionic acid and yalactic acid can also be used as appropriate.

The polyisocyanate that is the component (B) constituting the present invention is a curing agent for the polyol of the component (A>), and aliphatic, alicyclic, and aromatic polyisocyanates or a mixture thereof can be used. .

Aliphatic systems are generally hexamethylene diisocyanate (H
MDI>, the alicyclic system is isophorone diisocyanate (I
PDI), the aromatic type is tolylene diisocyanate (TD
I>, diphenylmethane diisocyanate (MD
I>, polyphenylmethane polyisocyanate (
Typical examples include crude MD I), xylylene diisocyanate (XD I), trimeric compounds having a buret or isocyanurate structure, and addition reaction compounds of these polyisocyanates and polyols. From the viewpoint of painting workability and physical properties of a cured coating film, aromatic polyisocyanates such as crude MDI and TDI are preferred.

The polyol (A>component) of the present invention includes component (a),
(b) and (c) were transesterified at 200 to 250°C using a basic catalyst if necessary.
It is obtained by subjecting component (d) to a ring-opening addition reaction.

(a) Ingredient castor oil is (a), (b), (c)
50-95% of the total of each component, preferably 70-9%
If it is less than 50% by weight, the viscosity of the paint increases and the smoothness of the coating film is lost. On the other hand, if it exceeds 95% by weight, the properties approach those of castor oil alone, and the coating film hardness is low and corrosion resistance is poor.

The dihydric alcohol of component (b) is 1 to 30% by weight, preferably 2 to 10% by weight. If it is less than 1% by weight, the impact resistance of the coating film will be poor, and if it exceeds 30% by weight, the coating film will be deteriorated. hardness is extremely reduced.

(c) Component trihydric or higher alcohol has 3 to 30! m%
If the amount is less than 3% by weight, the crosslinking density of the coating film will decrease, the hardness of the coating will decrease, and it will easily swell when immersed in water, and if it exceeds 30% by weight, the coating film will deteriorate. becomes brittle, and impact resistance and adhesion are significantly reduced.

(d) component ε-caprolactone is (a), (b)
, for 100 parts by weight of the polyol consisting of (c),
It is used in a proportion of 3 to 30 parts by weight and imparts compatibility and flexibility to the resin, but if it is less than 3 parts by weight, the effect is small, and if it exceeds 30 parts by weight, the hardness of the coating film decreases.

Further, the number average molecular weight of the polyol is suitably 1000 or less, and the hydroxyl value is suitably 150 to 350. If the number average molecular weight exceeds 1000, the workability during coating and painting operations will be poor, and if the hydroxyl value is less than 150, the crosslinking density will be low, resulting in a decrease in coating film hardness and poor corrosion resistance. On the other hand, if it exceeds 350, physical properties such as impact resistance and flexibility deteriorate.

The polyisocyanate of component (B) has an equivalent ratio (NCO/OH> of the hydroxyl group of the polyol that is the component and the isocyanate group of the polyisocyanate) of (0.6 to 1.6).
/1.0 is used, but the equivalence ratio is 0.6
If it is less than 1.6, the curing will be insufficient, and if it exceeds 1.6, the physical properties will be significantly deteriorated, and both will have a negative effect on corrosion resistance.

In addition to the constituent parts of the urethane coating composition, if necessary, dibutyltin dilaurate, dibutyltin diacetate-1.
Organic metal compounds and various amines such as titanium oxide and Bengara are added as reaction catalysts.

Organic or inorganic coloring pigments such as yellow lead, zinc white, carbon black, phthalocyanine blue, red lead.

Rust preventive pigments such as calcium leadate, zinc chromate, basic lead chromate, zinc molybdate, condensed zinc phosphate, silica,
Palite, calcium carbonate, clay.

It is also possible to mix extender pigments such as talc and mica, and use various smoothing agents, moisture absorbers, silanes, titanium coupling agents, etc. as auxiliary agents. The solvent-free two-component urethane paint of the present invention is applied while rotating the pipe treated with a wire brush or the like, but a primer may also be used at this time.

The solvent-free two-component ``rutan paint'' of the present invention can be used at room temperature or at
Although spraying or centrifugal spraying at a temperature of 90 DEG C. has been used, two-gun airless spraying is particularly preferred. In order to improve painting workability and prevent damage to the paint film, it is desirable to heat the cement pipe to 30 to 90°C before painting. The film thickness is aimed at one position on the inner surface, but the film thickness can be adjusted as desired.

[effect] According to the present invention, the film is 0.1 to several meters thick and has impact resistance.

It is possible to obtain a cement pipe coated with a urethane paint that has excellent chemical resistance, water resistance, and corrosion resistance.

[Example] The present invention will be explained below with reference to Examples.

■ Example of urethane resin composition (Example 1) (A> Polyol +!! 88 parts by weight of castor oil, 9 parts by weight of pentaerythritol,
1.3 M parts of 4-butanediol were added to 0.0% of lithium hydroxide.
After carrying out the transesterification reaction at 250'C for 1 hour in the presence of 2 parts by weight of ε-caprolactone, the
After 3 hours of reaction, the hydroxyl value was 298. A polyol with a viscosity of 11°/voice (25°C) is 19.

(Examples 2 to 9) In the same manner as in Example 1, castor oil and polyhydric alcohol were transesterified and ε-caprolactone was added to obtain a series of polyols.

Table 1 shows the components and characteristic values of each polyol.

(Comparative Examples 10 to 16) In the same manner as in Example 1, castor oil and polyhydric alcohol were transesterified, and ε-caprolactone was added to the grains to obtain polyols as comparative examples. However, Comparative Example 15
Only the transesterification of castor oil with 1,4-butanediol and pentaerythritol was carried out without addition of ε-caprolactone.

Table 1 shows the components and characteristic values of each polyol.

■ Example of coating a cement pipe (Example 17) After polishing the inner surface of a cement pipe with a nominal diameter of 250φ and a length of 2400 mm to remove surface laitance, coat it with epoxy using polyamide resin as a hardening agent. Apply resin clear and heat to 50℃ in a soaking oven.
A tube was coated with urethane resin paint having the composition shown in Example 1.
When the coating was applied to a thickness of approximately 1 m using the hot airless centrifugal projection method using a Nippon Gray Hydracat while rotating at rpm, it cured to a handleable state in approximately 2 minutes after application, and the coating was made using urethane with mirror-like smoothness. A resin paint coated cement pipe was obtained.

After leaving this coated cement pipe at room temperature for one week,
It was cut to a size of x200m, and the unpainted part was painted with tar epoxy paint, and after the cool epoxy paint had hardened, it was immersed in a sulfur RLI solution containing 5% molecule for 6 months, but the urethane resin paint part did not blister. It was proven that the cement pipe was sufficiently protected without cracking or cracking. In the case of unpainted pipes tested at the same time, surface disintegration was observed within 3 days.

(Example 18) After polishing the inner surface of a cement pipe with a nominal diameter of 800 φ and a length of 2000 m with a whetstone, the surface was further polished with a wire brassier to make it smooth, and the pipe was heated to 35°C in a soaking furnace.
A tube was coated with urethane resin paint having the composition shown in Example 1.
When the paint was applied to a thickness of approximately 1Mri by hot airless spray painting using Nippon Gray's Hydracat while rotating at RL)m, it hardened to a handleable level in approximately 5 minutes after application, and the painted surface had a mirror-like smoothness. A cement pipe coated with urethane resin paint was obtained.

(Example 19) After polishing the inner surface of a cement pipe with a nominal diameter of 800φ and a length of 200αm using a wire brush shear to remove surface laitance, epoxy clear using polyamide resin as a hardening agent was applied, and the tube was heated in a soaking furnace. When the urethane resin paint having the composition shown in Example 1 was heated to 40°C and hot airless spray painting was performed while rotating the tube in the same manner as in Example 18, it showed a hardening that could be handled in about 3 minutes. A cement pipe coated with urethane resin paint with a mirror-like smooth coating surface was obtained.

Table 1 summarizes the polyol resin composition, paint formulation, and performance test results. The resin composition and paint composition are expressed in units of 1,000 years.

When making a paint, the main ingredient is the polyol resin mixed with each pigment and certified to JIS 5400 B, 2B at Lumil today.
The particles were dispersed until the particle size was 25 to 30 μm as determined by .

In addition, the test plates used for the performance test were airless coated using an Asahi Ohsumi variable type two-component hot airless coater to a thickness of 0.7 to 1.0 mm, and then dried and cured indoors for 7 days. I used something.

Note 1. As the synthetic zeolite, Zeolum A4 manufactured by Toyo Soda was used.

The main rule was added at the time when pigment dispersion of the main ingredient was completed due to its functionality.

Note 2. Triethylenediamine is used as a catalyst for promoting the reaction, and its amount was determined so that the flow time of the mixture of the base agent and curing agent would be 2 to 3 minutes.

Note 3. Crude Ml] is Mitsubishi Kasei Corporation's PA
PI-135 (N00% 31.3>) was used.

Note 4. As the modified MDI, Coronate 2Q61 (N0022%) manufactured by Nippon Polyurethane Co., Ltd. was used.

Note 5. Rubber hardness test is polyethylene seams]・4~ on top
5In! Apply airless coating to a thickness of n and cure 1
1 Peel off the paint film from the polyethylene sheet 50x50m
The pieces were cut into pieces of size and measured using a Shore hardness tester.

Note 6. *The impact test was performed by airless painting on a 1.6X70X15ONrX sandblasted steel plate and applying JIS 5400.
6.138 method. Test conditions are radius 6.35±
The shooting die and receiver of 0.03m++ are sandwiched between the stand with the coating surface facing upward, and there is damage such as cracking and peeling due to the deformation of the coating that occurs when a weight of mass 'IKy is dropped from a height of 50cm. If there was no damage, continuous impact was applied until further damage occurred.

Note 7. The bending test was based on the bending test of JIS G3492, which was applied to a 1.6 x 100 x 300 sI sandblast plate, and the extrusion distance until cracking occurred on the coating surface was tested.

Note 8. The salt spray test was carried out on a 1.6 x 70 x 150 m sandblasted board, and after making scratches that reached the base, JI
After testing for 3000 hours using S K 54007.8, an NT cutter was inserted into the uneven part and the distance until the film could no longer be peeled off from the uneven part was tested.

Note 9. In the water absorption test, a 50 x 50 m test piece prepared in the same manner as Note 5 rubber hardness test was immersed in running water, and the weight increase after immersion was expressed as the produced water absorption rate (%) using the following formula.

(Wo-W / W) xloo W = weight before immersion Wo-Important information after soaking

Claims (1)

[Scope of Claims] (A) (a) 50 to 95% by weight of castor oil, (b) 1 to 30% by weight of dihydric alcohol, (c) 3 to 30% by weight of polyhydric alcohol of trihydric or higher valence, each component With respect to 100 parts by weight of the polyol obtained by reacting so that the total sum is 100% by weight, 3 to 30 parts by weight of (d) ε-caprolactone is further reacted with a number average molecular weight of 1000 or less and a hydroxyl value of 150 to 100. 350 polyol and (B) polyisocyanate as essential components, and the equivalent ratio of isocyanate groups to hydroxyl groups of the polyol (NCO/OH
) is (0.6-1.6)/1.0. A cement pipe coated with a solvent-free two-component urethane coating composition.