JPH03275782A - Primer composition and resin-coated metal - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent heat-resistance and adhesivity to metals and especially high hot-water resistance and suitable for pipe, etc., by compounding a specific imide prepolymer, a specific alkyl silicate precondensate and a polyphenylene sulfide resin. CONSTITUTION:The objective composition is composed of (A) an imide prepolymer expressed by formula (R1 is aromatic tetracarboxylic acid residue; R2 is aromatic diamine residue; R3 is unsaturated acid anhydride residue; n is integer of 0-5), (B) an alkyl silicate precondensate having 1-4C alkyl group and (C) powder of a polyphenylene sulfide resin. The preferable weight ratio of A:B is 97:3 to 25:75 (especially 95:5 to 30:70) and the preferable ratio of (A+B):C is 95:5 to 40:60.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a primer composition for coating a metal body surface with a polyphenylene sulfide resin and a metal body coated with a polyphenylene sulfide resin.

(Prior art) Polyphenylene sulfide resin (hereinafter abbreviated as PPS resin) has excellent heat resistance, hot water resistance, chemical resistance, mechanical strength, etc., and has good fluidity during melt molding, making it suitable for forming into metal objects. It is used as a coating resin.

When coating the surface of a metal object with this PPS resin, in order to obtain excellent coating performance, it is necessary to
It is necessary to bake at a high temperature of about ~400°C to allow the curing reaction to proceed sufficiently. Furthermore, in order to strengthen the adhesion between the resin coating layer and the metal surface, it is necessary to use a primer with excellent heat resistance.

As a primer for PPS resin of this type, for example, Japanese Patent Laid-Open No. 63-251477 specifically discloses a primer composition comprising an imide prepolymer and PPS resin powder.

(Problem B to be Solved by the Invention) Although the PPS resin-coated metal body using the above primer composition has fairly good adhesion to both the PPS resin coating layer and the metal body, it is still insufficient. In particular, if used for a long time under hot water, the adhesion will decrease and the coating will become blistered.
blistering) or peeling may occur.

The present invention is intended to solve the above-mentioned conventional problems, and its purpose is to provide a primer composition and resin that have excellent heat resistance and excellent adhesion between both the PPS resin coating layer and the metal body. An object of the present invention is to provide a coated metal body.

(Means for Solving the Problems) The primer composition of the present invention is a primer m paraboloid for coating a PPS resin on a metal body surface, and comprises a doble polymer represented by the following formula and a carbon alkyl group. The number is l
It consists of an alkyl silicate initial condensate of ~4 and PPS resin powder.

Here, R is an aromatic tetracarboxylic acid residue, R2 is an aromatic diamine residue, R3 is an unsaturated acid anhydride residue, and n is 0.
It is an integer of ~5.

Further, the resin-coated metal body of the present invention has a primer layer formed on the surface of the metal body using the primer composition of the present invention,
It is coated with PPS resin.

Another resin-coated metal body of the present invention has a base primer layer formed on the surface of the metal body using a base primer composition comprising the imide prepolymer and an alkyl silicate initial condensate having an alkyl group of 1 to 4 carbon atoms. A primer layer made of the primer composition of the present invention is formed thereon, and a PPS resin is coated thereon.

With the above configuration, the object of the present invention is achieved.

The imide prepolymer of the above formula used in the present invention can be prepared by reacting an aromatic tetracarboxylic acid, an aromatic diamine, and an unsaturated acid anhydride, or It can be obtained by reacting an aromatic diamine with an unsaturated acid anhydride.

Examples of aromatic tetracarboxylic acids include 3.3', 4.4 benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 2,3.6.7-naphthalenetetracarboxylic dianhydride, 3.3', 4,4°-diphenyltetracarboxylic dianhydride, 2,2'', 3.3-diphenyltetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis (3,4-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, etc. are used.

Examples of aromatic diamines include 2,2゛-bis(4-aminophenoxydiphenyl)propane, 1.3bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, and 4,4゛-bis(4-aminophenoxydiphenyl)propane. -bis(4-aminophenoxy)diphenyl, p-phenylenediamine, m-phenylenediamine, 3,3''-diaminodiphenylmethane, 3,3''-oxydianiline, 4,4''-cyanodiphenylmethane, 3,3'' -cya-5nodiphenyl sulfide, 44'-diaminodiphenyl sulfide, 3,
3′-Diamino diphenyl sulfone, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 1
．． 5-diaminonaphthalene, 2,6-diaminonaphthalene, n-xylene diamine, n-) lylene diamine,
Tolidine base, n-aminobenzylamine, p-aminobenzylamine, etc. are used.

As the unsaturated acid anhydride, 5-norbornene-2,3-
Dicarboxylic anhydride, 3,6-nindomethylene-L2,
3.6-titrahydrophthalic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, maleic anhydride, 4-ethynyl phthalic anhydride, and alkyl-substituted and halogen-substituted products thereof, etc. used.

In the above imide prepolymer formula 0, if the number n is 6 or more, the cured film of this imide prepolymer will bow against heat, which is not preferable. All or part of the group may be an amic acid, which is a precursor of an imide.

The alkyl silicate initial condensate having 1 to 4 carbon atoms used in the present invention has the general formula 5i (OR') (OR2) (OR3
) (OR') (wherein R1, R2, R3 and R4 are each an alkyl group having 4 or less carbon atoms) in an organic solvent in the presence of a suitable catalyst such as hydrochloric acid, It can be obtained by adding the necessary amount of water for partial hydrolysis.

As the organic solvent, a solvent common to the above-mentioned imide prepolymer or a solvent compatible with the solvent is used. When the number of carbon atoms in the alkyl group is 5 or more, agglomerations occur when mixed with the imide prepolymer, reducing miscibility.
Furthermore, it takes a long time to cure, which is not practical.

Examples of the above alkyl silicate include tetraethyl silicate, tetramethyl silicate, triethyl monobutyl silicate, dimethyl diethyl silicate, trimethyl monopropyl silicate, trimethyl monobutyl silicate, monomethyl triethyl silicate, dimethyl dibutyl silicate, triethyl monobutyl silicate,
Triethyl monotert-butyl silicate, diethyl dibutyl silicate, diethyl tertiary butyl silicate, tetrapropyl silicate, tetraisopropyl silicate, monoethyl tributyl silicate,
Diisopropyl dibutyl silicate, monoisopropyl triisobutyl silicate, monoisopropyl tritert-butyl silicate, tri-butyl mono-tert-butyl silicate, tetra-butyl silicate, tetra-isobutyl silicate, tetra-secondary-butyl silicate, tetra-tert-butyl silicate etc. Among these alkyl silicates, tetraethyl silicate is most preferred.

The PPS resin used in the present invention is composed of alternating benzene-sulfur bonds, and may be partially oxidized, branched, or crosslinked. Examples of such PPS resins include Rydon V-1 manufactured by Fili Nobs Vetroleum and T-4 manufactured by Torbren. Such PPS resin is used as a powder, and its particle size is preferably 300 μm or less, more preferably 100 μm or less.

If the particle size is as large as 300 μm or more, good dispersion in the primer composition may not be obtained and adhesion may decrease.

Therefore, in the present invention, the above imide prepolymer, an alkyl silicate initial condensate having 1 to 4 carbon atoms, and PPS resin powder are blended. The blending ratio of the imide prepolymer and the alkyl silicate initial condensate having 1 to 4 carbon atoms is preferably in the range of 97:3 to 25 nia 5 by weight, more preferably 95:5 to 30 nia 0 in weight ratio. is within the range of

When the amount of imide prepolymer added increases, the cured product of this prepolymer has adhesive properties to metal bodies, but its water resistance against penetration of water vapor and water decreases, resulting in a decrease in adhesiveness to metal bodies. Conversely, when the amount of the alkyl silicate initial condensate compounded increases, the adhesion between the PPS resin coating layer and the primer layer decreases.

Furthermore, the blending ratio of the total amount of imide prepolymer and alkyl silicate initial condensate to the PPS resin powder is preferably in the range of 95=5 to 40:60 in terms of weight ratio. When the amount of the imide prepolymer and the alkyl silicate initial condensate increases and the PPS resin powder decreases, the adhesion between the PPS resin coating layer and the primer layer decreases. Conversely, when the amount of imide prepolymer and alkyl silicate initial condensate decreases and the amount of PPS resin powder increases,
Residual stress increases and the adhesion between the primer layer and the metal body decreases.

The primer composition made of the above-mentioned imide prepolymer, alkyl silicate initial condensate, and PPS resin powder is generally composed of an imide prepolymer and an alkyl silicate! tI
It is used by dissolving PPS resin powder in an organic solvent and dispersing PPS resin powder therein. Examples of organic solvents include dimethylacetamide, dimethylformamide, N-methylvitritone, and methylethylketone. There are ethanol, etc.

In addition, an inorganic filler may be added to the primer composition of the present invention, if necessary. This inorganic filler has the function of reducing residual stress in the primer layer and preventing the occurrence of cranks. Examples of such inorganic fillers include metals, metal oxides, glass, carbon, and ceramic inorganic salts.

Examples of metals include zinc, nickel alloy, stainless steel, and cast iron. Examples of metal oxides include Al≧S, iron oxide, titanium oxide, zirconium oxide, chromium oxide, nickel oxide, potassium titanate, talc, kaolin, clay, and mica. This includes potassium titanate. In addition to those included in metal oxides, ceramics include silicon nitride, titanium nitride, boron carbide, silicon carbide, and the like. Inorganic salts include barium sulfate.

These inorganic fillers are preferably contained in the form of fibrous, granular, or flake-like fine powder, and the average particle size is 1
The thickness is adjusted to 100 μm, preferably 5 to 30 μm.

This inorganic filler is preferably contained in an amount of 10 to 800 parts by weight per 1 part of 100ffi of the primer composition.
More preferably, it is 25 to 400 parts by weight. If it is less than 10 parts by weight, the effect of the inorganic filler will be small, and the
When the weight part is less than L, the binder ability of the primer composition decreases, and the adhesion to the metal object decreases.

In addition, a silane coupling agent having affinity with imide prepolymers and PPS resins may be blended as necessary. As such a silane coupling agent, one having an amino group, mercapto i, or chloromethyl aromatic group as a terminal group is preferable.

The primer composition of the present invention is applied to the surface (surface or inner surface) of metal bodies such as iron, aluminum, stainless steel, and various alloys. Next, baking is performed, the imide prepolymer in the primer composition is crosslinked and hardened by heat, the alkyl silicate initial condensate is crosslinked and hardened by moisture in the air, and the PPS resin powder is melted and hardened.
A primer layer is formed.

The metal body is previously subjected to appropriate pretreatment such as sandblasting, degreasing, and chemical conversion treatment. Baking temperature is usually 300″C
More preferably, it is 350-420. The thickness of the primer layer is 5-100 um, preferably 10-30 μm.
It is assumed that the range is m. If it is less than 5 μm, the primer layer will not be formed uniformly, and pinholes and cranks will likely occur. On the other hand, if the thickness exceeds 100 μm, the adhesion between the primer layer and the metal body decreases.

The metal body surface (surface or inner surface) on which the primer layer is formed is coated with PPS resin. As this PPS resin, the same PPS resin as used in the above primer composition is used.

As the coating method, an electrostatic powder coating method using PPS resin powder is suitably employed.

After powder coating, the painted surface is baked, and the PPS resin is melted and hardened to form a resin coating layer. Baking temperature is 3
00-450°C is preferred. The thickness of the resin coating layer is 50
~2000 μm, preferably 250-1000 pm
The range of If it is less than 50 μm, the resin coating layer will not be formed uniformly, and pinholes and cracks will easily occur. On the other hand, if it exceeds 2000 μm, it takes time to bake, etc., and foaming occurs, making it impossible to obtain a dense resin coating layer.

After baking, annealing treatment or rapid cooling may be performed.

In particular, in the present invention, before applying the above-mentioned primer composition to the metal surface, a base primer composition consisting of the above-mentioned imide prepolymer and an alkyl silicate initial condensate having an alkyl group of 1 to 4 carbon atoms is applied. It is preferable to form a base primer layer by applying the primer composition of the present invention thereon to form a primer layer. By forming the base primer layer on the surface of the metal body in this way, the base primer layer does not contain crystalline PPS resin, so the generation of residual stress is reduced and the adhesion with the metal body is improved. and the adhesion with the primer layer thereon also improves.

In this case, the blending ratio of the imide prepolymer and the alkyl silicate initial condensate whose alkyl group has 1 to 4 carbon atoms is as follows:
The weight ratio is preferably in the range of 98:2 to 60:40. Note that the above-mentioned inorganic filler and silane coupling agent may also be blended into this base primer composition.

(Function) The primer composition of the present invention is composed of an imide prepolymer, an alkyl silicate initial condensate whose alkyl group has 1 to 4 carbon atoms, and PPS resin powder. The function of the imide resin formed by curing the imide prepolymer increases the adhesion with the metal body, and the function of the PPS resin therein increases the adhesion with the same PPS resin to be coated.

In this case, the imide resin formed by curing the imide prepolymer has heat resistance, but is relatively weak against hot water, and residual stress caused by the crystalline PPS resin contained in the primer layer also increases. Therefore, adhesion tends to deteriorate under hot water.

However, the primer layer contains a cured product of an alkyl silicate initial condensate, and this cured product of an alkyl silicate initial condensate has strong adhesion to metal bodies and is resistant to hot water. Therefore, even if there is residual stress due to the PPS resin, the hardened product of the alkyl silicate initial condensate increases the adhesion to the metal body, especially the hot water resistance. The cured product of the imide resin and alkyl silicate initial condensate formed by curing the primer composition and the PPS resin both have excellent heat resistance and good miscibility.

(Example) Examples and comparative examples of the present invention are shown below.

1. 2.2"-bis(4-aminophenoxydiphenyl)propane 24.5 g, 3,3",4.4"-hensiphenonetetracarboxylic dianhydride 9.7 g, 5-norbornene-2 , 9.8 g of 3-dicarboxylic anhydride were sequentially dissolved in 130 g of dimethylacetamide.

This solution was stirred for 6 hours, left to stand for 18 hours, and poured into water to cause precipitation. The deposited precipitate was separated by filtration, and 110
After drying under vacuum for 8 hours at "C", the mixture was ground in a mortar to obtain an orange imide prepolymer.

Further, 100 parts by weight of tetraethyl silicate (content calculated as SiOz is 40% by weight) and 1 part by weight of 4 caps of ethanol were thoroughly mixed in a glass reactor, and 1 weight of 1N hydrochloric acid was added to this while stirring. 1 part and 9 parts by weight of water were continuously added dropwise over 2 hours. After stirring for 3 hours after the completion of the dropwise addition, the stirring was stopped, and the mixture was allowed to stand for 20 hours to obtain an ethanol solution of the initial condensate of tetraethyl silicate.

10 parts by weight of the above imide prepolymer, ethanol solution of tetraethylsilicate initial condensate (solid content 50% by weight), 5 parts by weight of PPS resin powder (particle size 90 μm or less) (Rydon v-1, manufactured by Phillips Vetroleum) ,
Kaolin (particle size 90 μm or less) 10 parts by weight, N, N'
- 40 parts by weight of dimethylacetamide was blended and mixed uniformly to prepare a primer composition.

After glysothoblasting an iron plate with a thickness of 3 mm x 100 mm x 100 am, it was cleaned by blowing compressed air, the above primer composition was applied with a brush to one side of the iron plate, and this was baked at 380°C for 30 minutes. . The thickness of the obtained primer layer was 25 μm on average. Electrostatic powder coating of PPS resin powder (T-4: L--Blen Co., Ltd.) was applied on this primer layer, and then this was coated at 380°C for 6 hours.
After baking for 0 minutes, the product was put into water and rapidly cooled to obtain a PPS resin-coated iron plate. The thickness of the obtained coating layer was approximately 900 μm.
Met.

Regarding the PPS resin-coated iron plate obtained in this way,
A normal adhesion test and a hot water resistance test were conducted using the following test methods. The results are shown in Table 1.

(1) Normal adhesion test The coating film on the PPS resin-coated iron plate is cut with a sharp knife in a 10-inch width so that the cut reaches the iron plate, one end is peeled off, and this is heated at room temperature (23°C). Peeling speed 10a
The peel strength was measured by pulling in a 90 degree direction for 1 minute. Note that the * mark in the table indicates that the PPS resin coating layer was broken.

(2) Hot water resistance test A PPS resin-coated iron plate was immersed in hot water with the coating layer side at 95°C and the iron plate side at 65°C for 100 hours. Ta.

The same procedure as in Example 1 was carried out except that the PPS resin powder (Rydon v-1) used in Example 1 was changed to 20 parts by weight.

The same procedure as in Example 1 was carried out except that the ethanol solution of the tetraethyl silicate initial condensate in Example 1 was changed to 2 parts by weight.

1 Example 1 The procedure was carried out in the same manner as in Example 1, except that the ethanol solution of the tetraethyl silicate initial condensate in Example 1 was changed to 2 parts by weight, and the PPS resin powder (Rydon v-1) was changed to 15 parts by weight. Ta.

Example 1 was carried out in the same manner as in Example 1, except that the ethanol solution of the tetraethyl silicate initial condensate in Example 1 was changed to 40 parts by weight.

Same as Example 1, except that the ethanol solution of the initial condensate of tetraethyl silicate in Example 1 was changed to 1 part by weight, and the PPS resin powder (Rydon v-1) was changed to 30 parts by weight. went.

10 parts by weight of the imide prepolymer of Example 1, 10 parts by weight of an ethanol solution of tetraethylsilicate initial condensate,
171,340 parts by weight of N,N'-dimethylacetate was blended and mixed uniformly to prepare a base primer U.

The same procedure as in Example 1 was carried out, except that before applying the primer composition of Example 1 to a grid-blasted iron plate, the above-mentioned base primer U acid was applied.

The comparison side was carried out in the same manner as in Example 1, except that the primer composition of Example 1 was not applied.

The same procedure as in Example 1 was carried out except that the PPS resin powder (Rydon Sea 1) of Example 1 was not blended.

The same procedure as in Example 1 was carried out except that the imide prepolymer of Example 1 was not blended.

The same procedure as in Example 1 was repeated except that the ethanol-Bii solution of the tetraethylsilicate initial condensate of Example 1 was not blended.

(The following is a blank space) A resin-coated metal body having excellent adhesion between the PPS resin and the metal body shown in Table 1 and particularly good hot water resistance can be obtained.

Therefore, the resin-coated metal body of the present invention can be suitably used for corrosion protection of metal surfaces that come into contact with hot water, such as pipes and joints for hot water supply, and vibrators and joints for chemical plants.

Claims (1)

[Claims] 1. A primer composition for coating a metal body surface with a polyphenylene sulfide resin, which comprises an imide prepolymer represented by the following formula and an alkyl group having 1 to 4 carbon atoms.
A primer composition comprising an alkyl silicate initial condensate and polyphenylene sulfide resin powder. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Here, R_1 is an aromatic tetracarboxylic acid residue, R_2
is an aromatic diamine residue, R_3 is an unsaturated acid anhydride residue,
n is an integer from 0 to 5. 2. A resin-coated metal body, in which a primer layer made of the primer composition according to claim 1 is formed on the surface of the metal body, and a polyphenylene sulfide resin is coated thereon. 3. A base primer layer of a base primer composition comprising the imide prepolymer and an alkyl silicate initial condensate having an alkyl group of 1 to 4 carbon atoms is formed on the surface of the metal body, and the primer composition according to claim 1 is formed thereon. A resin-coated metal body on which a primer layer is formed and a polyphenylene sulfide resin is coated on the primer layer.