JP2001131476A - Polyurethane composition for cast coating of steel - Google Patents

Abstract

(57) [Summary] [Problem] To provide a resin composition for cast coating of a steel material having excellent properties such as corrosion protection, waterproofness, rust prevention, impact resistance, electric insulation, etc. of the coating and good workability of cast coating. I do. (A) 30 to 70 parts by weight of a castor oil-modified polyol having four or more hydroxyl groups in a molecule and mainly composed of a polyester-polyether covalent bond; (b) two or more hydroxyl groups and / or amino groups 6 to 15 parts by weight of a compound having a hydroxyl group and / or an amine value having a hydroxyl group and / or an amine value of more than 225 mgKOH / g; and (c) 10 to 30 parts by weight of a castor oil polyol or a castor oil-modified polyol having 2 to 3 hydroxyl groups. A liquid comprising components A and (d) a liquid B which is an organic polyisocyanate compound, and NCO / (OH + N
A polyurethane composition for casting and coating a two-component reaction type steel material having a molar ratio of H ₂ ) of 0.9 to 1.2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane composition for casting and coating a steel material, and more particularly, to a method in which a thick coating is applied to the surface of a steel material for the purpose of corrosion protection, waterproofing, rust prevention, impact resistance, electrical insulation, and the like. The present invention relates to a polyurethane composition for casting and coating a steel material for forming a mold.

[0002]

2. Description of the Related Art Steel materials such as steel pipes and section steels are often buried in soil or erected and laid in the sea or rivers. To improve their corrosion resistance, polyethylene, epoxy resin, polyester, etc. A coated steel material coated with a resin-based material or the like is used.

[0003] The main body of the coated steel material can be coated at a factory, but the area around the joint must be coated at the installation site. In addition, there are few cases where it is necessary to locally coat an existing iron structure with a resin. In such field coating,
It is difficult to form a uniform thick film by brush-coating or spray-coating a resin paint, and it is also difficult to secure long-term corrosion resistance due to defects such as pin poles.

[0004] Therefore, the present inventors have previously proposed a coating method and a coating apparatus for coating a coated steel material using a split mold (for example, in Japanese Patent Application Laid-Open No. 9-327834). According to such means, a sound film having an arbitrary thickness can be formed on the surface of the steel material at the installation site.

Conventionally, various resin compositions such as urethane-based, epoxy-based and polyester-based resins have been proposed as cast coating resin coatings. However, these are components designed to suit each coating object and purpose of use, and as a coating for casting coating of steel as described above,
A resin composition having various necessary properties has not been obtained.

[0006]

SUMMARY OF THE INVENTION A coating made of a high corrosion-resistant steel material has a strength, an impact resistance and a weather resistance, as well as a water resistance capable of withstanding use in soil and water and preventing electrochemical corrosion. Electrical insulation is required. In addition, in the above-mentioned casting coating, in order to improve the workability, a resin coating material having appropriate viscosity and curing speed and capable of forming a thick film without defects is desired.

Therefore, the present invention can form a coating film having excellent properties such as corrosion protection, waterproofing, rust prevention, impact resistance, and electrical insulation, has good workability of casting coating, and is uniform and free from defects. An object of the present invention is to provide a resin composition for casting and coating a steel material capable of forming a thick film.

[0008]

The gist of the present invention for solving the above-mentioned problems is as follows: (a) Castor oil-modified polyol mainly containing a polyester-polyether covalent bond having four or more hydroxyl groups in the molecule. And (b) a hydroxyl value of 225 mgK
Polyol higher than OH / g, amine value 225mgK
A polyamine higher than OH / g or one or more of each having a hydroxyl group and an amino group, wherein the sum of the hydroxyl value and the amine value is 225 mgK
A compound higher than OH / g, and (c) castor oil polyol,
Castor oil-modified diol, Castor oil-modified triol or a liquid A having a mixture of two or more of them as a main component, and (d) a liquid B which is an organic polyisocyanate compound; (a) 30 to 70 parts by weight of polyol, (b) 6 to 15 parts by weight of compound, and (c) polyol 1
0 to 30 parts by weight, (a) the polyol in the solution A,
The average hydroxyl value or the sum of the average hydroxyl value and the average amine value in the compound (b) and the polyol (c) is 140 to 200 mgK.
OH / g, and (a) the polyol in the solution A,
(b) a two-liquid reaction type in which the molar ratio NCO / (OH + NH ₂ ) between the hydroxyl group and amino group contained in the compound and the polyol and the isocyanate group contained in the solution B is 0.9 to 1.2. Is a polyurethane composition for cast coating of steel materials.

The polyurethane composition for casting coating of the present invention comprises, as the polyol in the solution A, a castor oil-modified polyol ((a) polyol) mainly composed of polyester-polyether covalent bonds and a castor oil or its modified polyol ( (c) polyol) to improve water resistance and electrical insulation.

In order to obtain various properties such as high hardness, high elasticity and corrosion resistance, and to obtain an appropriate viscosity for the work of casting coating, a polyol having a relatively low hydroxyl value (a) polyol and hydroxyl value are used. It is a mixture of a moderate (c) polyol and a (b) compound having a high hydroxyl value and / or a high min value.

Further, the compound (b) is necessary for increasing the hardness, but if the compound (b) is used for hard segmentation, elongation and elasticity are insufficient, and the corrosion resistance (volume resistivity) is reduced. Therefore, a suitable amount of the polyol (a) having a certain degree of hard segmenting effect is also blended so as to combine high hardness, rust prevention effect and elongation.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each compound in the polyurethane composition of the present invention and its compounding ratio will be described. (a) the polyol has four or more hydroxyl groups in the molecule,
Castor oil-modified polyol having an average molecular weight of about 1,800 and having a copolymer of polyester and polyether as a skeleton, such as DESMOPHEN-1150 (manufactured by Bayer), URIC-KS-10D (manufactured by Ito Oil Co., Ltd.), etc. Is a polyol commercially available under the trade name

The blending ratio of the polyol (a) in the solution A must be 30 to 70 parts by weight with respect to 100 of the solution A. If the amount exceeds 70 parts by weight, the elongation of the coating becomes insufficient, and if it is less than 30 parts by weight, the amount of the polyol (c) relatively increases, and the hardness and strength of the coating decrease. In addition, a more preferable mixing ratio of the (a) polyol,
It is 30 to 60 parts, more preferably 40 to 50 parts by weight.

The compound (b) has a hydroxyl value of 225 mg KO
Polyol higher than H / g, amine value 225 mg KO
Polyamine higher than H / g or each having at least one hydroxyl group and an amino group, the sum of the hydroxyl value and the amine value being 225 mg KO
The compound is higher than H / g.

For example, compounds such as polyoxyalkylene polyol, polytetramethylene ether glycol, polyester polyol, bis (2-hydroxypropyl) aniline, dianodiphenylmethane, methylenebis (octochloroaniline), phenylenediamine, tolylenediamine, ethylenediamine, etc. Is raised.

It is necessary that the compounding ratio of the compound (b) in the liquid A is 6 to 15 parts by weight. If the amount exceeds 15 parts by weight, the polyurethane film becomes high in hardness, the elongation decreases, cracks occur in the flat test, and as a result, the insulation resistance also decreases. If the amount is less than 6 parts by weight, the strength and hardness of the coating become insufficient. The more preferred compounding ratio of the compound (b) is 6 to 10 parts by weight.

The polyol (c) in the solution A is a modified castor oil polyol derived from castor oil and having two or three hydroxyl groups in a molecule. The castor oil polyol and the castor oil-modified diol (for example, castor oil Modified with ethylene glycol or the like to make two hydroxyl groups in one molecule), castor oil-modified triol, or a mixture of two or more of these.

The compounding ratio of the polyol (c) in the solution A is 10 to
It must be 30 parts by weight. If the amount exceeds 30 parts by weight, the hardness of the coating film decreases, and the mechanical strength becomes insufficient. If this is less than 10 parts by weight,
This is because the amount of the polyol (a) is relatively large, and the elongation of the film is reduced. In addition, a more preferable mixing ratio of the (c) polyol is 10 to 20 parts by weight.

In the polyurethane composition according to the present invention, (a) a polyol, (b) a compound and (c)
The sum of the average hydroxyl value (the hydroxyl value of a mixture of these three compounds at a predetermined mixing ratio) in the polyol or the average amine value (the meaning of the average is the same as described above) is 1
It is necessary to be in the range of 40 to 200 mgKOH / g. If this value is less than 140, the hardness will be insufficient and the strength will decrease. On the other hand, if it exceeds 200, elongation and elasticity become insufficient, and cracks and cracks may occur at the time of vibration and impact.

The (d) isocyanate in the liquid B includes:
Crude diphenylmethane diisocyanate (crude MDI), liquid diphenylmethane diisocyanate (liquid MDI),
MDI-based NCO-terminated prepolymers, such as pure MDI
NCO-terminated prepolymer, crude MDINCO-terminated prepolymer, liquid MDI (containing carbodiimide group) NCO-terminated prepolymer, and the like. In particular, crude MDI is preferred from the viewpoint of properties such as viscosity and curability and price.

(D) The isocyanate is reacted with NCO / (OH + N) with respect to the hydroxyl group and amino group contained in (a) polyol, (b) compound and (c) polyol in solution A.
It is necessary to mix them so that the molar ratio of H ₂ ) is in the range of 0.9 to 1.2. When this ratio is less than 0.9, the hardness becomes insufficient and the tackiness remains, while the ratio becomes less than 1.2.
When the ratio is more than 1, free isocyanate groups react with moisture in the air to easily cause blisters on the coating layer.

The polyurethane composition of the present invention may further comprise, if necessary, an extender, a flame retardant plasticizer, a flame retardant, a catalyst and other auxiliaries (hereinafter collectively referred to as (e) additives).
Can be included.

(E) As a catalyst for the additive, a plurality of nitrogen-containing linear or cyclic tertiary amines and quaternary ammonium salts which are amine catalysts are used. For example, triethylenediamine, a double salt of triethylenediamine, dimethyltriethylenediamine, a triethylenediaminedipropylene glycol solution, and the like.

Dibutyltin dilaurate, stannas octoate, dibutyltin diacetate, lead octylate,
Organometallic compounds such as lead naphthenate are not preferred because they have a hydrolysis promoting effect.

Examples of the extender include calcium carbonate, magnesium carbonate, talc, clay, silica sand kaolin, diatomaceous earth and the like. From the viewpoint of water resistance, seawater resistance, chemical resistance and the like, it is preferable to use talc or clay as a main component.

The flame-retardant plasticizer is effective for lowering the flammability, raising the ignition temperature, delaying the ignition time, etc .; it has good compatibility with the polyol and does not deteriorate the coating film properties; Is not required. Examples thereof include bromine-based, chlorine-based, iodine-based, and fluorine-based ones. In the present invention, phosphoric acid esters and phosphorus compounds, among which tris (monochloropropyl) phosphate and triarylisopropylated phosphate, are used. preferable.

Like the flame retardant plasticizer, the flame retardant is effective in lowering the flammability, increasing the ignition temperature and delaying the ignition time, and does not reduce the compatibility with the polyol and the properties of the coating film. A requirement that no toxic gas is generated during combustion is given as a necessary requirement. To meet these requirements,
Examples include antimony trioxide, chlorinated paraffin compounds, mixtures of antimony trioxide and bromine compounds (composite flame retardants), aluminum hydroxide, and the like. Examples of the auxiliary include an antifoaming agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, a coloring agent and an antioxidant.

The amount of the additive catalyst is appropriately adjusted depending on the desired injection time. As shown in Example 2 below, it has been confirmed that the film characteristics do not change much even when the amount of the catalyst added is changed. Preferably, the extender is 10 to 25 parts by weight. If the amount exceeds 25 parts by weight, the injection viscosity becomes high and workability becomes difficult.

The flame retardant plasticizer is preferably used in an amount of 10 to 20 parts by weight. If the amount exceeds 20 parts by weight, the compatibility becomes poor and the reaction is slowed down. Become. The amount of the flame retardant is preferably 5 to 15 parts by weight, and if it exceeds 15 parts by weight, it may cause a delay in hardness development time and a bleeding phenomenon.

The cast coating of a steel material using the polyurethane composition of the present invention may be carried out, for example, by the following method. (a) polyol, (b) compound, (c) polyol and
(e) A predetermined amount of the additive is uniformly dissolved and mixed, and heated and dehydrated in a vacuum (water content: 0.05% or less). Keep in storage.

On the other hand, a preheated mold is set on the steel coating portion so that a desired coating thickness can be obtained. The two liquids in the tank are heated to a predetermined temperature by flowing through the heater hose, and are injected from the injection port of the mold using a two-liquid mixing / injection machine to perform coating. At this time, the injection time, the curing time, and the mold release time can be adjusted by the addition amount of the catalyst, the liquid temperature, the mold temperature, and the discharge amount of the injection machine.

Solution A dissolved and mixed in the same manner as described above, and heated and dehydrated under vacuum, and (d) B containing isocyanate as a main component
The liquid is mixed and stirred with an electric mixer at a predetermined mixing ratio,
Inject from the injection port of the mold set in the same manner as above and apply coating. In this case, the injection time depends on the amount of catalyst added,
Adjust the curing time and release time.

By such a cast coating method, it is possible to coat the steel material locally at an arbitrary thickness on the surface of the steel material, and no pinholes or internal pinholes are generated, and the film thickness is uniform. A polyurethane resin film having excellent properties such as impact resistance, insulation resistance and seawater resistance can be obtained.

[0034]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” refers to parts by weight based on the A liquid 100.

Example 1 (a) DESMOPHEN-1150 was used as a polyol.
(Hydroxyl value 160 mgKOH / g) 35 to 56 parts, (b)
6-10 parts of bis (2-hydroxypropyl) aniline (hydroxyl value 582 mgKOH / g) as a compound, (c)
As a polyol, 10-17 parts of a modified castor oil polyol (hydroxyl value: 270 mgKOH / g), 10 parts of (e) a flame retardant plasticizer Reophos R-35 (triaryl isopropyl phosphate) as an additive, and 10 parts of a flame retardant Combined flame retardant (mixed with antimony trioxide and bromine compound)
12 parts, 8 to 17 parts of talc as a bulking agent, 0.01 part of a double salt of DABCO DC-1 (manufactured by San Apro) triethylenediamine as a catalyst, a coloring agent and an antifoaming agent are added, and they are mixed uniformly. Then, the solution A was dehydrated by heating under vacuum.

[0036]

[Table 1]

The mixing ratio of the polyols (a) and (c) and the compound (b) is varied in several steps within the above-mentioned range, and a liquid A is prepared respectively, and this and the (d) isocyanate are crude MDI. Solution B is mixed so that the molar ratio of NCO / (OH + NH ₂ ) becomes 1.05 (weight ratio of solution A / solution B ≒ 3/1), and this mixture is poured into a mold on the surface of steel material. And film thickness 3
mm of coating was formed. The coating was measured for hardness, tensile strength, elongation, tear strength, water absorption and insulation resistance, and was also evaluated for self-extinguishing properties and an impact test. Table 1 shows the results.

As a comparative example, the case where (a) polyol was not blended in solution A and only (c) polyol and (b) compound were used (Comparative Example 1) and (c) polyether was used in place of (c) polyol Polyol (hydroxyl value 280mgKOH / g)
(E) in solution A in the case of using (Comparative Examples 2 to 5)
The mixing ratio of the additive, the weight ratio with the solution B, and the method of forming the coating film were the same as those described above, and the same measurement as above was performed. Table 2 shows the results of these comparative examples.

[0039]

[Table 2]

In Comparative Examples 2 and 3, MOCA (4,4'-diamino-3,3'-dichlorodiphenylmethane, amine value 420 mgKOH / g) was used as the compound (b). As shown in Table 1, in each of Inventive Examples 1 to 6 in which each component in the solution A was within the range of the present invention, the insulation resistance of the coating was large, the mechanical properties were also appropriate values, The test did not crack. On the other hand, in Comparative Examples 1 to 5 in Table 2, the mechanical properties were not particularly problematic, but it was determined that the volume resistivity was small and the corrosion protection performance was insufficient.

Example 2 The compositions of Solution A and Solution B and the weight ratio of the two are shown in Table 1 of Example 6 of the present invention.
(E) By changing the type and amount of the catalyst as an additive, the effects of the amount of catalyst added on the pot life and the properties of the coating were investigated. The method of forming the coating and the method of measuring various characteristics were the same as in Example 1. Table 3 shows the survey results.

[0042]

[Table 3]

As can be seen from Table 3, the pot life can be arbitrarily adjusted in the range of 2 to 13 minutes by changing the amount of catalyst added, and in each case, the properties of the coating are good. Was confirmed.

[0044]

According to the present invention, it is possible to form a coating film having excellent properties such as corrosion protection, waterproofing, rust prevention, impact resistance, and electrical insulation. It has become possible to provide a resin composition for casting and coating a steel material capable of forming a thick film having no thickness.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masami Ishida 2-6-3 Otemachi, Chiyoda-ku, Tokyo New Nippon Steel Corporation (72) Inventor Keita Suzumura 2-6-Otemachi, Chiyoda-ku, Tokyo No. 3 Inside Nippon Steel Corporation (72) Inventor Kotaro Yoshida 2--11-9 Iwamotocho, Chiyoda-ku, Tokyo Japan Inside Iron Corrosion Protection Corporation (72) Inventor Toyo Ando 2-chome, Iwamotocho, Chiyoda-ku, Tokyo No. 9 Day Inside Steel Corrosion Protection Co., Ltd. (72) Yoshiyuki Kawase, Inventor 2-11-9, Iwamotocho, Chiyoda-ku, Tokyo Japan Inside Steel Corrosion Protection Co., Ltd. No. 4 Urethane Giken Kogyo Co., Ltd. F term (reference) 4J034 BA07 BA08 CA01 CA04 CA15 CB03 CB07 CC03 CC12 CC22 CC26 CC45 CC52 CC61 CC65 CC67 CD13 DA01 DB04 DB05 DB07 DC50 DF01 D F20 DG01 DG02 DG06 HA01 HA07 HC12 HC22 HC46 HC64 HC71 KA01 KB04 KC17 KC18 KD02 QA02 QA03 QC06 RA07 4J038 DG051 DG061 DG111 DG131 DG271 DG281 NA01 NA03 NA04 NA11 NA21 NA23 PA01 PC02 4K0612 AB13 BC06

Claims (1)

[Claims] 1. A castor oil-modified polyol having (a) a polyester-polyether covalent bond having at least 4 hydroxyl groups in the molecule, and (b) a hydroxyl value of 225 mg KOH.
/ G higher polyol / amine value 225 mg KOH
/ G having a hydroxyl value and an amine value of at least 225 mgKOH
/ G, and (c) a liquid A containing a castor oil polyol, a castor oil-modified diol, a castor oil-modified triol or a mixture of two or more of these compounds as main components;
(d) liquid B, which is an organic polyisocyanate compound, in the liquid A, (a) 30 to 70 parts by weight of a polyol,
(b) 6 to 15 parts by weight of compound and (c) polyol 10
30 parts by weight, (a) the polyol in the solution A, (b)
The average hydroxyl value of the compound and the polyol (c) or the sum of the average hydroxyl value and the average amine value is 140 to 200 mg KOH.
/ G, and the molar ratio NCO / (OH + NH) of the hydroxyl group and the amino group contained in the (a) polyol, the (b) compound and the (c) polyol in the solution A, and the isocyanate group contained in the solution B. ₂ ) is 0.9 to 1.2 2
A polyurethane composition for cast coating of a liquid reaction type steel material.