JP5630651B2 - Articles having a heat-resistant paint and a film formed by curing the heat-resistant paint. - Google Patents

Description

  The present invention relates to a paint having excellent heat resistance and an article having a film formed by curing the paint.

Metal materials exposed to a thermal environment of about 150-250 ° C, such as automobile parts, cooking utensils, boilers, heating equipment, chemical equipment, electric wire coating materials, and electronic boards, are more Opportunities to be exposed to high temperature environments are increasing. Such metal materials are often provided with a heat-resistant paint film on the surface in order to maintain corrosion resistance. The heat-resistant paint generally comprises a resin binder excellent in heat resistance and a rust preventive pigment excellent in corrosion resistance. Examples of the heat resistant paint include a silicone resin or an epoxy resin and a black pigment, the black pigment contains manganese and copper, and the manganese content in the black pigment is 25 to 45% by mass in terms of MnO. Further, a heat-resistant paint is known in which the content of copper in the black pigment is 5 to 25% by mass in terms of CuO and the content of silicon in the black pigment is 3% by mass or less in terms of SiO ₂ . (For example, refer to Patent Document 1).

  In recent years, there are cases where problems such as embrittlement of the coating film in a further high temperature environment and peeling due to internal stress due to thermal expansion occur, and there is an increasing demand for a coating agent exhibiting higher heat resistance. In response to this demand, the application of a polyamic acid type imide resin exhibiting low thermal decomposition and low thermal expansion properties as a resin binder for heat resistant paints is being studied.

  However, a cured coating film of a heat-resistant paint containing the polyamic acid type imide resin generally has poor metal adhesion. In addition, heat-resistant paints using a polyamic acid type imide resin must be applied to an object to be coated, and then heated at about 300 ° C. to form a imide ring by closing the polyamic acid to form a cured coating film. There is also a problem in that heat is applied to the object and the physical properties of the object to be coated are adversely affected. In particular, in a metal article surface-treated with a treatment agent such as zinc phosphate or a plated metal article as an object to be coated, there is a problem that the surface layer treated in the heating step for generating an imide ring is peeled off from the metal article.

JP 2010-155890 A

  An object of the present invention is to provide a heat-resistant paint that is hardly deteriorated by heat even when exposed to a high temperature for a long time and has good adhesion to an object to be coated such as metal, and a film obtained by curing the paint. It is to provide an article having.

  As a result of intensive studies, the present inventors have been exposed to high temperatures for a long time by using a polyimide resin containing a specific proportion of a biphenyl skeleton and a logarithmic viscosity of 0.2 to 0.8 dl / g as a binder resin. The present invention has been found that the thermal modification of the coating film hardly occurs even when left in an environment, the coating film has good adhesion to metal, and the dimensional stability of the coating film is good. It came to complete.

  That is, the present invention has a biphenyl skeleton directly linked to a 5-membered ring imide skeleton, the content of the biphenyl skeleton is 20 to 45% by mass, and the logarithmic viscosity is 0.2 to 0.8 dl / g. It provides a heat resistant paint characterized by containing a polyimide resin (A) and an epoxy resin (B).

  The present invention also provides an article characterized by having a film formed by curing the heat-resistant paint.

  The heat-resistant paint of the present invention is not easily heat denatured even when exposed to a high temperature for a long time, and is excellent in adhesion to a metal. Therefore, it should be used for mufflers of a cooking utensil, boiler, heating equipment, chemical device, electric wire coating material, electronic board, magnet, four wheels and internal combustion engine, or a saddle-ride type self-propelled vehicle, and a suction ring in the internal combustion engine. Can do.

  The polyimide resin (A) used in the present invention has a biphenyl skeleton directly linked to a five-membered ring imide skeleton, the content of the biphenyl skeleton is 20 to 45% by mass, and the relative viscosity is 0.2 to 0.00. 8 dl / g. When the content of the biphenyl skeleton is less than 20% by mass, it is not preferable because low linear expansion (dimensional stability) is hardly exhibited. When the content of the biphenyl skeleton is larger than 45% by mass, it is not preferable because solvent solubility and low-temperature meltability are hardly exhibited. The content of the biphenyl skeleton is preferably 25 to 40% by mass because a thermosetting resin composition having both low linear expansion and low temperature meltability is obtained, and more preferably 25 to 35% by mass.

  The content of the biphenyl structure is such that the molecular weight is 152 when the biphenyl structure is bonded to the polyimide resin main chain and the molecular weight is 150 when the biphenyl structure is bonded at 4 positions. It can be calculated from the ratio of the biphenyl structure to the weight.

  When the logarithmic viscosity of the polyimide resin (A) used in the present invention is less than 0.2 dl / g, it is not preferable because a cured product having sufficient strength cannot be obtained. If the logarithmic viscosity is greater than 0.8 dl / g, the resin solution stability is significantly impaired (increased viscosity), which is not preferable. The logarithmic viscosity of the polyimide resin (A) is preferably 0.2 to 0.7 dl / g because a cured product having sufficient strength can be obtained and the stability of the resin solution is exhibited. When calculating | requiring stability of a resin solution, logarithmic viscosity has preferable 0.2-0.5 dl / g. When low linear expansion is required, the logarithmic viscosity is preferably 0.3 to 0.7 dl / g.

  Therefore, the polyimide resin (A) used in the present invention is preferably a polyimide resin having a biphenyl skeleton content of 25 to 40% by mass and a logarithmic viscosity of 0.2 to 0.7 dl / g.

In the present invention, the logarithmic viscosity of the polyimide resin was determined under the following conditions.
A polyimide resin was dissolved in N-methyl-2-pyrrolidone so that the resin concentration was 0.5 g / dl to obtain a resin solution. The solution viscosity of the resin solution and the solvent viscosity (viscosity of N-methyl-2-pyrrolidone) were measured at 30 ° C. with an Ubbelohde type viscosity tube, and the obtained measured values were obtained by applying the following formulas. .

Logarithmic viscosity (dl / g) = [ln (V1 / V2)] / V3
In the above formula, V1 represents the solution viscosity measured with an Ubbelohde type viscosity tube, and V2 represents the solvent viscosity measured with an Ubbelohde type viscosity tube. Here, V1 and V2 were determined from the time required for the resin solution and the solvent (N-methyl-2-pyrrolidone) to pass through the capillary of the viscosity tube. V3 is the polymer concentration (g / dl).

  The polyimide resin (A) includes, for example, a polyisocyanate compound (a1) having a biphenyl structure and / or an acid anhydride (a2) having a biphenyl structure, and a polyisocyanate compound (a3) other than (a1) as necessary. It can be easily obtained by reacting an acid anhydride (a4) other than (a2).

  Examples of the polyisocyanate compound (a1) having a biphenyl structure include 4,4′-diisocyanate-3,3′-dimethyl-1,1′-biphenyl, 4,4′-diisocyanate-3,3′-diethyl. -1,1'-biphenyl, 4,4'-diisocyanate-2,2'-dimethyl-1,1'-biphenyl, 4,4'-diisocyanate-2,2'-diethyl-1,1'-biphenyl, 4,4'-diisocyanate-3,3'-ditrifluoromethyl-1,1'-biphenyl, 4,4'-diisocyanate-2,2'-ditrifluoromethyl-1,1'-biphenyl, tolidine diisocyanate or tolidine And polyisocyanates derived from diisocyanates.

  Examples of the acid anhydride (a2) having a biphenyl structure include biphenyl-3,3 ′, 4,4′-tetracarboxylic acid, biphenyl-2,3,3 ′, 4′-tetracarboxylic acid, and these Monoanhydrides, dianhydrides, and the like. These can be used alone or as a mixture of two or more.

  Examples of the polyisocyanate compound (a3) other than (a1) include aromatic polyisocyanates and aliphatic polyisocyanates other than (a1).

  Examples of the aromatic polyisocyanate other than (a1) include p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 2,4-tolylene diisocyanate, and 2,6-tolylene diisocyanate. 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 3,3'-diethyldiphenyl-4,4'-diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, , 3-bis (α, α-dimethylisocyanatomethyl) benzene, tetramethylxylylene diisocyanate, diphenylene ether-4,4′-diisocyanate and naphthalene diisocyanate.

  Examples of the aliphatic polyisocyanate compound include hexamethylene diisocyanate, lysine diisocyanate, trimethylhexamethylenemethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, hydrogenated xylene diisocyanate, and norbornene diisocyanate.

  As the polyisocyanate compound, it is also possible to use an isocyanate prepolymer obtained by reacting the polyisocyanate compound and various polyol components in advance with an excess of isocyanate groups.

  The polyimide resin used in the present invention may have a branched structure in order to improve solvent solubility and compatibility with other resins. As the branching method, as the polyisocyanate compound, for example, a tri- or higher functional polyisocyanate compound having an isocyanurate ring that is an isocyanurate body such as the diisocyanate compound, a burette body, an adduct body, an allohanate body of the diisocyanate, or Polymethylene polyphenyl polyisocyanate (crude MDI) or the like may be used.

  Examples of the acid anhydride (a4) other than (a2) include aromatic tricarboxylic acid anhydrides, alicyclic tricarboxylic acid anhydrides other than (a2), and tetracarboxylic acid anhydrides other than (a2). . Examples of aromatic tricarboxylic acid anhydrides other than (a2) include trimellitic anhydride and naphthalene-1,2,4-tricarboxylic acid anhydride.

  Examples of the alicyclic tricarboxylic acid anhydride include cyclohexane-1,3,4-tricarboxylic acid anhydride-3,4-anhydride, cyclohexane-1,3,5-tricarboxylic acid anhydride-3,5-anhydride, And cyclohexane-1,2,3-tricarboxylic acid anhydride-2,3-anhydride.

  Examples of tetracarboxylic acid anhydrides other than (a2) include pyromellitic dianhydride, benzophenone-3,3 ', 4,4'-tetracarboxylic dianhydride, diphenyl ether-3,3', 4. , 4'-tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2 , 4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, decahydronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 4, 8-Dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8- Tetracarboxylic dianhydride, , 7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthrene- 1,3,9,10-tetracarboxylic dianhydride, berylene-3,4,9,10-tetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3 , 4-dicarboxyphenyl) methane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,3-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone Anhydride Bis (3,4-carboxyphenyl) ether dianhydride,

Ethylene glycol bisanhydro trimellitate, propylene glycol bis anhydro trimellitate, butanediol bis anhydro trimellitate, hexamethylene glycol bis anhydro trimellitate, polyethylene glycol bis anhydro trimellitate, polypropylene lenglycol bis Anhydro trimellitate, other alkylene glycol bisan hydroxy trimellitate, etc. are mentioned.

  The polyimide (A) used in the present invention is preferable because a polyimide resin having a benzophenone structure further exhibits heat resistance and low linear expansion. A polyimide resin having a benzophenone structure can be obtained, for example, by using benzophenone tetracarboxylic acid anhydride as an essential component in the production method.

  The content of the benzophenone structure is preferably from 1 to 30% by mass based on the mass of the polyimide resin, since a cured product having excellent heat resistance is obtained, and more preferably from 5 to 20% by mass is excellent in synthetic stability.

  The content of the benzophenone structure can be calculated from the ratio of the benzophenone structure to the total weight of the polyimide resin, with the molecular weight of the benzophenone structure having 4 bonding points to the polyimide resin main chain being 178.

In addition, the polyimide (A) used in the present invention is preferable because a polyimide resin having a tolylene structure bonded to the main chain at the 2- and 4-positions easily exhibits melt adhesion and low linear expansion. A polyimide resin having a tolylene structure bonded to the main chain at positions 2 and 4 can be obtained, for example, by using toluene diisocyanate as an essential component in the production method.
The content of the tolylene structure bonded to the main chain at the 2nd and 4th positions is based on the ratio of the tolylene structure to the total weight of the polyimide resin, assuming that the molecular weight of the tolylene structure bonded at the 2nd and 4th positions to the polyimide resin main chain is 150. Can be calculated.

  The content of the tolylene structure bonded to the main chain at positions 2 and 4 in the polyimide resin is preferably 1 to 20% by mass because it is excellent in synthetic stability, and 2 to 14% by weight is low in linear expansion and synthetic stability. More preferable.

  In the said manufacturing method, a polyisocyanate compound and the compound which has an acid anhydride group react. The ratio (ma) / (mb) of the number of moles of isocyanate groups in the polyisocyanate compound (ma) and the total number of moles of non-hydroxyl groups and carboxyl groups in the compound having an acid anhydride group (mb) is expressed as the molecular weight. A ratio of 0.7 to 1.2 is preferable, and a ratio of 0.8 to 1.2 is more preferable because a polyimide resin from which a large polyimide resin can be easily obtained and a cured product having excellent mechanical properties is obtained. Moreover, since it is easy to obtain the polyimide resin which is excellent in storage stability, the (ma) / (mb) is more preferably in the range of 0.9 to 1.1. In addition, when using together carboxylic anhydrides, such as trimellitic anhydride, said (mb) is the total number of moles of a hydroxyl-free group and a carboxyl group in all the carboxylic anhydrides.

  In the case of producing in a one-step reaction in the production method, for example, a reaction vessel is charged with a polyisocyanate compound and a compound having an acid anhydride group, and the reaction is allowed to proceed while decarboxylation by heating while stirring. .

  The reaction temperature can be in the range of 50 ° C. to 250 ° C., and is preferably performed at a temperature of 70 ° C. to 180 ° C. in terms of reaction rate and prevention of side reactions.

  The reaction is preferable because the stability of the resulting polyimide resin is improved when the reaction is performed until almost all isocyanate groups have reacted. Moreover, you may make it react by adding an alcohol and a phenol compound with respect to the isocyanate group which remains a little.

  In producing the polyimide resin (A) used in the present invention, it is preferable to use an organic solvent because a uniform reaction can proceed. Here, the organic solvent may be present after being present in the system in advance or may be introduced in the middle. In order to maintain an appropriate reaction rate, the proportion of the organic solvent in the system is preferably 98% by mass or less of the reaction system, more preferably 10 to 90% by mass, and more preferably 40 to 90% by mass. % Is more preferable. As such an organic solvent, since a compound containing an isocyanate group is used as a raw material component, an aprotic polar organic solvent having no active proton such as a hydroxyl group or an amino group is preferable.

  As the aprotic polar organic solvent, for example, polar organic solvents such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, and γ-butyrolactone can be used. In addition to the above solvents, ether solvents, ester solvents, ketone solvents, petroleum solvents and the like may be used as long as they are soluble. Various solvents may be mixed and used.

  In particular, use of dimethylacetamide is preferred from the viewpoint of reducing the amount of residual solvent when the coating film is dried and cured, and the solubility of the polyimide resin.

  Examples of ether solvents that can be used in the method for producing a polyimide resin used in the present invention include ethylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and ethylene glycol dibutyl ether; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, Polyethylene glycol dialkyl ethers such as diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, and triethylene glycol dibutyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, etc. Polyethylene glycol monoalkyl ether acetates such as diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monomethyl ether acetate, triethylene glycol monoethyl ether acetate, triethylene glycol monobutyl ether acetate Alkyl ether acetates;

Propylene glycol dialkyl ethers such as propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether; dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dibutyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol Polypropylene glycol dialkyl ethers such as propylene glycol dibutyl ether; propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate; Polypropylene glycol monoalkyl ether acetate such as triglycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, tripropylene glycol monomethyl ether acetate, tripropylene glycol monoethyl ether acetate, tripropylene glycol monobutyl ether acetate Dialkyl ethers of copolymerized polyether glycols such as low molecular weight ethylene-propylene copolymers; monoacetate monoalkyl ethers of copolymerized polyether glycols; alkyl esters of copolymerized polyether glycols; Examples include ether glycol monoalkyl esters and monoalkyl ethers. It is.

  Examples of the ester solvent include ethyl acetate and butyl acetate. Examples of the ketone solvent include acetone, methyl ethyl ketone, and cyclohexanone. In addition, as the petroleum solvent, it is also possible to use toluene, xylene, other high-boiling aromatic solvents, and aliphatic and alicyclic solvents such as hexane and cyclohexane.

  Whether or not the polyimide resin (A) used in the present invention is dissolved in an organic solvent was determined by adding the polyimide resin concentration of the present invention to 10% by mass in the organic solvent and allowing to stand at 25 ° C. for 7 days. Then, it can carry out by observing an external appearance visually.

  The polyimide resin (A) used in the present invention may be a polyimide resin having a linear structure or a polyimide resin having a branched structure. Further, the copolymer component may have a polyester-modified polyesterimide or urethane-modified polyurethaneimide structure.

  Examples of the terminal structure of the polyimide resin (A) used in the present invention include structures such as carboxylic acid, carboxylic acid anhydride, isocyanate group, and amine group. As the terminal structure, the structure of the carboxylic acid or its anhydride is preferable because the stability of the polyimide resin itself of the present invention and the stability after blending with an organic solvent or another resin are good. When the terminal structure is a carboxylic acid or its anhydride structure, the acid value is a polyimide resin with a solid content acid value of 1 to 200, which makes it easy to handle, and a film or molded product with excellent mechanical strength and dimensional stability can be obtained. To preferred.

  The molecular weight of the polyimide resin (A) used in the present invention is preferably from 1,000 to 200,000, more preferably from 5,000 to 80,000 because a polyimide resin (A) that is easy to handle is obtained and a coating film having excellent mechanical strength and dimensional stability is obtained. The molecular weight can be measured by GPC or quantitative determination of the terminal functional group.

In the present invention, the weight average molecular weight (Mw) was measured using a gel permeation chromatograph (GPC) under the following conditions.
Measuring device: Tosoh Corporation HLC-8320GPC, UV8320
Column: Super AWM-H × 2 manufactured by Tosoh Corporation Detector: RI (differential refractometer) and UV (254 nm)
Data processing: Tosoh Corporation EcoSEC-WorkStation
Measurement conditions: Column temperature 40 ° C
Solvent DMF
Flow rate 0.35 ml / min Standard: Calibration curve prepared with polystyrene standard sample Sample: 0.2% by weight DMF solution in terms of resin solid content filtered through a microfilter (injection volume: 10 μl)

  Moreover, the polyimide resin (A) used by this invention has a preferable polyimide resin which does not have an alkylene structure.

  The epoxy resin (B) used in the present invention preferably has two or more epoxy groups in the molecule. Examples of such epoxy resins include bisphenol type epoxy resins such as bisphenol A type epoxy resins, bisphenol S type epoxy resins, and bisphenol F type epoxy resins; biphenyl type epoxy resins; naphthalene type epoxy resins; phenol novolac epoxy resins and cresol novolac types. Epoxy resins, novolak type epoxy resins such as bisphenol type novolacs; epoxidized products of various dicyclopentadiene modified phenolic resins obtained by reacting dicyclopentadiene with various phenols; epoxy resins having a fluorene skeleton; 10- (2,5 -Dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide and the like, and a phosphorus-containing epoxy resin; neopentyl glycol di Aliphatic epoxy resins such as ricidyl ether and 1,6-hexanediol diglycidyl ether; 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis- (3,4-epoxycyclohexyl) adipate, etc. And alicyclic epoxy resins; and heterocycle-containing epoxy resins such as triglycidyl isocyanurate. Among these, at least one epoxy resin selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, and naphthalene type epoxy resin is preferable, and naphthalene type epoxy resin is more preferable. preferable.

  Among the naphthalene type epoxy resins, an epoxy resin having a structure represented by the following formula is preferable.

（式中、Rは水素原子、メチル基、エチル基、フェニル基、ヒドロキシフェニル基である。）

(In the formula, R is a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or a hydroxyphenyl group.)

  Specific examples of the structure of the epoxy resin represented by the formula (1) include the following structural formulas (1-1) to (1-11).

  Among these epoxy resins, 1,1-bis (2,7-diglycidyloxy- represented by the structural formula (1-1) is preferable in terms of excellent fluidity, curability and heat resistance. 1-naphthyl) methane is preferred.

  The 1,1-bis (2,7-diglycidyloxy-1-naphthyl) alkane (a1) has an epoxy equivalent of 150 to 170 g / eq, an ICI viscosity at 150 ° C. of 2.0 to 6.0 poise, and water. It is preferable to use a degradable chlorine having a property value of 200 ppm or less because of excellent fluidity, curability and heat resistance.

  The 1,1-bis (2,7-diglycidyloxy-1-naphthyl) alkane (a1) is obtained by, for example, reacting 1,1-bis (2,7-dihydroxy-1-naphthyl) alkane with epihalohydrin. Can be obtained.

  Examples of the method for producing the 1,1-bis (2,7-dihydroxy-1-naphthyl) alkane include a method of reacting 2,7-dihydroxynaphthalene with aldehydes.

  Examples of the aldehydes include, but are not limited to, formaldehyde, acetaldehyde, propyl aldehyde, butyraldehyde, benzaldehyde, p-hydroxybenzaldehyde, and the like. It is preferable to use formaldehyde from the point of being excellent, in which case 1,1-bis (2,7-dihydroxy-1-naphthyl) alkane is 1,1-bis (2,7-dihydroxy-1). -Naphthyl) methane.

  The catalyst used in the reaction is not particularly limited, and may be either a basic catalyst or an acidic catalyst. Examples of the basic catalyst include sodium hydroxide, potassium hydroxide, lithium hydroxide, hydroxide Alkali metal hydroxides such as calcium or alkaline earth metal hydroxides, or alkali metal carbonates such as sodium carbonate and potassium carbonate can be used. Acidic catalysts include sulfuric acid, hydrochloric acid, nitric acid, hydrobromic acid, perchloric acid and other mineral acids, p-toluenesulfonic acid, benzenesulfonic acid and other sulfonic acids, oxalic acid, succinic acid, malonic acid, monochloroacetic acid, Carboxylic acids such as dichloroacetic acid are used. Usually, the amount of these catalysts used is preferably 0.01 to 0.1 mol with respect to 1 mol of 2,7-dihydroxynaphthalene. Although it may be used more than that, a large amount of acid or alkali and extra time are required for the neutralization step, so that it may be determined appropriately.

  More specifically, the method of reacting the 2,7-dihydroxynaphthalene and the aldehyde is described in detail. For example, in an aqueous dispersion, 1 mol of 2,7-dihydroxynaphthalene is added in the presence of a basic catalyst or an acidic catalyst. On the other hand, aldehydes are added in an amount of 0.5 to 1.0 mol, preferably 0.5 to 0.55 mol, and stirred at a temperature of 30 to 100 ° C., preferably 60 to 80 ° C. for 0.5 to 3 hours. Thereafter, after neutralization, the product is filtered off, washed with water, dried and then dried to obtain the target compound.

  The reaction product thus obtained is not a novolak product composed of a mixture of a dimerization product, a trimerization product, a tetramerization product, a pentamerization product, etc., but is a dimerization product with a production rate of substantially 100%. Only 1-bis (2,7-diglycidyloxy-1-naphthyl) alkane is obtained.

  In the present invention, the 2,7-dihydroxynaphthalene may be used alone, but other phenols and naphthols may be partially used together. At this time, as other phenols and naphthols to be used in combination, β-naphthol is preferable from the viewpoint that the dimerized product is formed at a substantially 100% component ratio.

  The reaction products when β-naphthol is used in combination are 1,1-bis (2,7-dihydroxy-1-naphthyl) alkane and 1- (2,7-dihydroxy-1-naphthyl) -1- (2 -Hydroxy-1-naphthyl) alkane and 1,1-bis (2-hydroxy-1-naphthyl) alkane are a mixture of three kinds of dimerization products.

  Subsequently, the 1,1-bis (2,7-dihydroxy-1-naphthyl) alkane thus obtained is reacted with epihalohydrone to give 1,1-bis (2,7-diglycidyloxy-1-naphthyl). ) The method for obtaining the alkane is not particularly limited. For example, the epihalohydrin is added in an amount of 1.5 to 20 with respect to 1 mol of the hydroxyl group of the 1,1-bis (2,7-dihydroxy-1-naphthyl) alkane. Mole, preferably 3.0 to 10.0 mol, can be easily produced by reacting at 20 to 120 ° C., preferably 50 to 80 ° C. for 2 to 7 hours in the presence of a base. (Hereinafter, the reaction of phenols with epihalohydrin is referred to as an epoxidation reaction.)

  The base used in the epoxidation reaction is not particularly limited, and examples thereof include potassium hydroxide, sodium hydroxide, barium hydroxide, magnesium oxide, sodium carbonate, and potassium carbonate. Sodium hydroxide is preferred.

  As epihalohydrin, epichlorohydrin, epibromohydrin, β-methylepichlorohydrin, and the like are used, and epichlorohydrin is preferable from the viewpoint of industrial availability.

  By adjusting the excess of the number of moles of epihalohydrin with respect to the number of moles of hydroxyl groups of the 1,1-bis (2,7-dihydroxy-1-naphthyl) alkane, the molecular weight, epoxy equivalent, and melt viscosity of the resulting epoxy resin are adjusted. Can be adjusted. Lowering the molar excess of epihalohydrin increases the molecular weight of the epoxy resin, and conversely increases the molecular weight. As the molecular weight increases, the epoxy equivalent and the melt viscosity also increase, and the heat resistance of the cured product tends to gradually decrease. However, generally, when the excess of the number of moles of epihalohydrin exceeds 10 times, the molecular weight, epoxy equivalent, and melt viscosity do not change so much, the range of 10 times or less is preferable from the viewpoint of economy.

  Depending on the conditions of the epoxidation reaction, the obtained epoxy equivalent, melt viscosity and purity differ, but the epoxy equivalent is 150 to 170 g / eq, the ICI viscosity at 150 ° C. is 2.0 to 6.0 poise, and hydrolyzable chlorine is It is preferable to adjust so as to have a property value of 200 ppm or less.

  The content of the epoxy resin (B) is 10 to 100% by mass with respect to 100 parts by mass of the polyimide resin (A), and the cured product has low linear expansion, and has excellent thermosetting properties at low temperatures. It is preferable from the resin composition obtained, 10-40 mass% is more preferable, 10-30 mass% is still more preferable.

  Moreover, since the viscosity of an epoxy resin (B) becomes a composition excellent in low temperature meltability, the epoxy resin whose viscosity in 150 degreeC is 12 Pa.s or less is preferable, and the epoxy resin of 10 Pa.s or less is more preferable.

  The heat-resistant paint of the present invention may further contain a sliding agent (C) as necessary. Examples of the sliding agent (C) include graphite (graphite), molybdenum disulfide, carbon, fluororesin, polyacetal, polyamide, polyphenylene sulfide, polyolefin resin, phenol resin, polyester, and the above-described solid lubricant material. Or a composite material obtained by subjecting the surface of the resin material to wear resistance treatment such as chromium plating. Among these, graphite (graphite) and molybdenum disulfide are preferable.

  When the heat-resistant paint of the present invention contains a pigment, the amount of the sliding agent (C) added is 0.5 to 50 parts by mass with respect to 100 parts by mass in total of the polyimide resin (A) and the epoxy resin (B). preferable.

  Moreover, the heat-resistant paint of the present invention can contain a pigment as required. As the pigment, for example, an anticorrosive pigment having corrosion resistance or the like is used, and the kind of the pigment is not particularly limited. As the anticorrosion pigment, for example, non-polluting pigments such as carbon black, zinc phosphate, aluminum phosphate, calcium phosphate, magnesium phosphate, zinc molybdate, and calcium molybdate are preferably used.

  As other pigments, scaly pigments are particularly preferably used in addition to ordinary extender pigments. The extender pigment can be appropriately selected from talc, kaolin, clay, precipitated barium sulfate, calcium carbonate and the like in consideration of heat resistance and in combination of one or more kinds. The scaly pigment can be appropriately selected from one or more kinds of glass flakes, mica, scaly iron oxide, scaly aluminum powder, and the like.

  The amount of the pigment added when the heat-resistant paint of the present invention contains the pigment is preferably 0.5 to 100 parts by mass with respect to 100 parts by mass in total of the polyimide resin (A) and the epoxy resin (B).

  In addition, various additives such as a reinforcing agent, a thickener, a curing agent, and a dispersing agent can be added to the heat-resistant coating material of the present invention as necessary.

  The article of the present invention has a film formed by curing a heat resistant paint. In order to form the film on the article, for example, there is a method of applying a heat-resistant paint to a substrate and performing a heat treatment. As a coating method, a known coating method (spray method, brush coating, etc.) may be used. The heat treatment conditions may be appropriately determined according to the type of resin or solvent, the solid content concentration of the paint, the thickness of the coating film, and the like. An undercoat layer containing a rust preventive pigment may be formed on the surface of the substrate in advance, and a blast treatment may be applied to improve the adhesion with the coating film.

  EXAMPLES Next, an Example is shown and this invention is demonstrated further in detail. Unless otherwise specified, “parts” and “%” are based on weight.

Synthesis Example 1 [Synthesis of Polyimide Resin (A)]
In a flask equipped with a stirrer, a thermometer and a condenser, 213.2 g of DMAC (dimethylacetamide), 6.29 g (0.036 mol) of TDI (tolylene diisocyanate), TODI (4,4′-diisocyanate-3,3 '-Dimethyl-1,1'-biphenyl) 37.8 g (0.143 mol), TMA (trimellitic anhydride) 29.0 g (0.151 mol), BTDA (benzophenone-3,3', 4,4) ′ -Tetracarboxylic dianhydride) and 12.2 g (0.038 mol) were added, the temperature was raised to 150 ° C. over 1 hour while paying attention to heat generation while stirring, and the reaction was carried out at this temperature for 5 hours. I let you. The reaction proceeded with the foaming of carbon dioxide, and the system became a brown transparent liquid. A polyimide resin solution (resin composition in which the polyimide resin was dissolved in DMAC) having a resin solid content of 20% with a viscosity of 2 Pa · s at 25 ° C. and a solution acid value of 12.8 (KOH mg / g) was obtained. This is abbreviated as polyimide resin (A1) solution. In addition, the solid content acid value of the resin calculated from the value was 64 (KOHmg / g). Moreover, it was the weight average molecular weight 10,000 as a result of the measurement of a gel permeation chromatography (GPC).

  The obtained polyimide resin (A1) solution was coated on a KBr plate, and the infrared absorption spectrum of the sample obtained by volatilizing the solvent was measured. As a result, 2270 cm-1 which is the characteristic absorption of the isocyanate group completely disappeared, and 725 cm- Characteristic absorption of the imide ring was confirmed at 1, 1780 cm <-1> and 1720 cm <-1>. The amount of carbon dioxide generated was 15.8 g (0.36 mol), which was monitored by the change in the flask content weight. From this, it is concluded that the total amount of 0.36 mol, which is the total amount of isocyanate groups, has been converted to imide bonds and amide bonds.

  Table 1 shows the blending amount of the raw material of the polyimide resin (A1), the content of the biphenyl skeleton, the logarithmic viscosity, the weight average molecular weight, and the solid content acid value.

Synthesis Examples 2, 4, 5, 6, 8, 9 [Synthesis of polyimide resin (A) and comparative polyimide resin (a)]
A solution of polyimide resins (A2), (A4) and a polyimide resin (A5), polyimide resins for comparison (a1), (a3) and ( A solution of a4) was obtained. As in Synthesis Example 1, the biphenyl skeleton content, logarithmic viscosity, weight average molecular weight and solid content acid value are shown in Table 1.

Synthesis Example 3 and Synthesis Example 7 [Synthesis of polyimide resin (A3) and comparative polyimide resin (a2)]
Polyimide resin in the same manner as in Synthesis Example 1 except that BPDA (BPDA: biphenyl-3,3 ′, 4,4′-tetracarboxylic anhydride) is used instead of BTDA and the blending ratio shown in Table 1 is used. A solution of (A3) was obtained. As in Synthesis Example 1, the biphenyl skeleton content, logarithmic viscosity, weight average molecular weight and solid content acid value are shown in Table 1.

Synthesis Example 10 [Synthesis of Comparative Control Polyimide (a5)]
To a flask equipped with a stirrer, thermometer and condenser, add 10.82 g of paraphenylenediamine, 0.9 g of water and 160.9 g of N-methyl-2-pyrrolidone, and dissolve at 50 ° C. under stirring and nitrogen flow. It was. While maintaining this temperature, 1.47 g (0.005 mol) of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride was added to this solution, and then 3,3 ′, 4,4′-biphenyl was added. Tetracarboxylic dianhydride was added slowly. Finally, the amount of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride used was 28.492 g. The viscosity of the obtained brownish brown transparent solution was 5 Pa · s, and a polyimide resin for comparison (a5) having a resin solid content of 18% was obtained.

Synthesis Example 11 [Synthesis of Epoxy Resin (B)]
To a stirrer, thermometer, and 4-neck flask, 320 g (2 mol) of 2,7-dihydroxynaphthalene and 320 g of isopropyl alcohol were added and mixed well. Thereafter, 3.3 g of 49% NaOH was added and the temperature was raised to 70 ° C. Next, 81 g of 37% formalin was added dropwise over 1 hour while maintaining the liquid temperature at 70 ° C. Thereafter, stirring was continued at 70 ° C. for 2 hours to complete the dimerization reaction. 1850 g (20 mol) of epichlorohydrin was added thereto, and 360 g (4.4 mol) of 49% NaOH was added dropwise at 50 ° C. over 3 hours. Thereafter, stirring was continued at 50 ° C. for 1 hour to complete the epoxidation reaction, stirring was stopped, and the lower layer was discarded. Next, after excess epichlorohydrin was recovered by distillation, 1000 g of MIBK was added to dissolve the crude resin. To this, 30 g of 10% NaOH was added and stirred at 80 ° C. for 3 hours, stirring was stopped and the lower layer was discarded. 300 g of water was added thereto and washed twice, followed by dehydration-filtration-desolvation to obtain 501 g of the desired epoxy resin (2). Epoxy resin (2) had an epoxy equivalent of 161 g / eq and an ICI viscosity at 150 ° C. of 3.8 poise.

Test Examples 1-9
The viscosity stability of the solutions of the polyimide resins (A1) to (A5) obtained in Synthesis Examples 1 to 9 and the solution of the polyimide resin for comparison (a1) to (a4) was evaluated according to the following method. The evaluation results are shown in Table 1.

<Method for evaluating viscosity stability of resin solution>
The initial viscosity immediately after synthesis and the viscosity after 25 ° C. × 7 days were measured with an E-type viscometer and evaluated according to the following criteria.
○: Viscosity after 7 days / initial viscosity = 1.0 to less than 1.5 Δ: Viscosity after 7 days / initial viscosity = 1.5 to less than 2.0 ×: Viscosity after 7 days / initial viscosity = 2.0 or more

Footnotes in Table 1 Inability to measure: Precipitates precipitated during synthesis and could not be obtained as a uniform solution, so measurement was not possible.
Not evaluated: Since a precipitate was precipitated in the resin solution and was not obtained as a uniform solution, it was not evaluated.

Examples 1-8 and Comparative Examples 1-10
The thermosetting resin compositions 1 to 8 of the present invention and the comparative thermosetting resin compositions 1 'to 10' were obtained with the formulations shown in Tables 2 to 4. Evaluation of the heat resistance of the hardened | cured material of the obtained composition, the adhesiveness to a base material, dimensional stability, a flame retardance, and a softness | flexibility was evaluated in accordance with the following method. The evaluation results are shown in Tables 2-5.

Evaluation of heat resistance of cured product Using thermogravimetric / suggested thermal analyzer (TG / DTA), thermogravimetric analysis up to 20-500 ° C under the conditions of 5 mg sample, heating rate 10 ° C / min, nitrogen atmosphere went. The weight loss results up to 500 ° C. were evaluated according to the following criteria.
×: Weight reduction of 75% or more Δ: Weight reduction of 50 to 75% ○: Weight reduction of 25 to 50% ◎: Weight reduction of 25% or less

Evaluation of Adhesiveness of Cured Product to Substrate Evaluation of adhesion of cured product to the substrate was performed by conducting a cross-cut tape peeling test and a high temperature slidability test of the cured coating film. The method of creating a coating film and the evaluation method in each evaluation are shown below.

<Cross-cut tape peeling test for cured coating>
-Method for creating cured coating film (Examples 1 to 8 and Comparative Examples 1 to 8)
The zinc phosphate-treated steel sheet was coated to a thickness of 20 μm after drying, preliminarily dried for 10 minutes in a 100 ° C. hot air drying path, and then dried for 60 minutes in a 200 ° C. hot air dryer.
-Method for creating cured coating film (Comparative Example 9 and Comparative Example 10)
The zinc phosphate chemical conversion steel sheet was dried and then coated to a thickness of 20 μm, pre-dried in a 100 ° C. hot air drying furnace for 10 minutes, and then dried in a 350 ° C. hot air drying furnace for 60 minutes.

<Evaluation method>
A grid-like cut reaching the substrate of the cured coating film was made using 11 cutter guides with an interval of 1 mm, the adhesive tape was peeled off, and evaluated according to the following criteria.
How about the following?
◎: Remaining number of coating films is 100 ○: Remaining number of coating films is 91-99 △: Remaining number of coating films is 0-90 ×: All coating films are peeled off from the substrate before peeling the adhesive tape

<High temperature slidability test of cured coating film>
-Preparation method of test pieces (Examples 1 to 8 and Comparative Examples 1 to 8)
The zinc phosphate-treated steel sheet was coated to a thickness of 20 μm after drying, preliminarily dried for 10 minutes in a 100 ° C. hot air drying path, and then dried for 60 minutes in a 200 ° C. hot air dryer.
-Preparation method of test piece (Comparative Example 9 and Comparative Example 10)
The zinc phosphate chemical conversion steel sheet was dried and then coated to a thickness of 20 μm, pre-dried in a 100 ° C. hot air drying furnace for 10 minutes, and then dried in a 350 ° C. hot air drying furnace for 60 minutes.

<Evaluation method>
After holding the test plate at a surface temperature of 200 ° C. with a hot plate and sliding the cured coating film surface with a stainless ball 1000 times with a load of 500 g, the cured coating film surface was observed, and the coating film was broken and peeled. Evaluation was performed according to the following criteria.

Destruction of the coating film A: The coating film is not broken after sliding 1000 times.
○: Breakage of the coating film can be confirmed after 500 to 999 times of sliding.
(Triangle | delta): The fracture | rupture of a coating film can be confirmed by 100 to 499 times of sliding.
X: Breakage of the coating film can be confirmed by sliding less than 100 times.

Peeling of coating film A: After sliding 1000 times, the coating film is not broken.
○: Breakage of the coating film can be confirmed after 500 to 999 times of sliding.
(Triangle | delta): The fracture | rupture of a coating film can be confirmed by 100 to 499 times of sliding.
X: Breakage of the coating film can be confirmed by sliding less than 100 times.

Evaluation of dimensional stability Dimensional stability was evaluated by measuring the linear expansion coefficient.
-Preparation of test piece The thermosetting resin composition was coated on a tinplate substrate so that the film thickness of the coating film obtained after curing was 30 µm. Next, this coated plate was dried with a dryer at 50 ° C. for 30 minutes, with a dryer at 100 ° C. for 30 minutes, and with a dryer at 200 ° C. for 60 minutes to form a coating film (film). After cooling to room temperature, the coating film (film) was cut into a predetermined size, isolated from the substrate, and used as a measurement sample.

・ Method of measuring linear expansion coefficient
Using a thermal analysis system TMA-SS6000 manufactured by Seiko Electronics Co., Ltd., measurement was performed by the TMA (Thermal Mechanical Analysis) method under the conditions of a sample length of 10 mm, a heating rate of 10 ° C./min, and a load of 30 mN.

Evaluation of flame retardancy-Preparation method of test pieces (Examples 1 to 8 and Comparative Examples 1 to 8)
After coating on a mirror-finished aluminum plate to a film thickness of 20 μm, pre-dry for 10 minutes in a 100 ° C. hot air drying path, and then dry for 60 minutes in a 200 ° C. hot air dryer, isolate the coating from the aluminum plate and test I got a piece.
-Preparation method of test piece (Comparative Example 9 and Comparative Example 10)
After coating on a zinc-formate-treated steel sheet with a thickness of 20 μm, it was pre-dried for 10 minutes in a hot air drying oven at 100 ° C. and then dried for 60 minutes in a hot air drying oven at 350 ° C. I got a piece.

Evaluation Method A test piece was cut out to 10 × 70 mm, ignited from one side, and the combustion state was observed.
○: Although it ignited, it was extinguished immediately.
(Triangle | delta): It ignited and spread to half of the test piece, and it extinguished after that.
X: The test piece was completely burned.

Evaluation of flexibility-Preparation method of test pieces (Examples 1 to 8 and Comparative Examples 1 to 8)
After coating on a mirror-finished aluminum plate to a film thickness of 20 μm, pre-drying for 10 minutes in a 100 ° C. hot air drying path, then drying for 60 minutes in a 200 ° C. hot air dryer, and peeling off the coating film from the mirror-like aluminum plate, A specimen was obtained.
-Preparation method of test piece (Comparative Example 9 and Comparative Example 10)
After coating on a mirror-finished aluminum plate to a film thickness of 20μm, pre-drying for 10 minutes in a 100 ° C hot-air drying oven and then drying for 60 minutes in a 350 ° C hot-air drying oven, peeling the coating film from the mirror-like aluminum plate, testing I got a piece.

<Evaluation method>
After the test piece was bent at 180 ° C., the coating surface was observed and evaluated according to the following criteria.
○: Cracks cannot be confirmed on the bent surface.
X: Cracks were confirmed on the bent surface.

Footnotes in Table 1 TDI: 2,4-tolylene diisocyanate TODI: 4,4'-diisocyanate-3,3'-dimethyl-1,1'-biphenyl TMA: trimellitic anhydride BTDA: benzophenone tetracarboxylic anhydride BPDA: biphenyl-3,3 ', 4,4'-tetracarboxylic anhydride HCA-HQ: 10- (2,5-dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide

Footnotes of Table 2 to Table 5 Epoxy resin (1): DIC phenol bisphenol A liquid epoxy resin Epicron 850-S (epoxy equivalent 188 g / eq)
Epoxy resin (2): The epoxy resin obtained in Synthesis Example 11.

Claims (13)

A polyimide resin (A) having a biphenyl skeleton directly connected to a five-membered ring imide skeleton, a content of the biphenyl skeleton of 20 to 45% by mass, and a logarithmic viscosity of 0.2 to 0.8 dl / g; , A heat resistant paint containing epoxy resin (B) ,
A heat resistant paint, wherein the polyimide resin (A) is a polyimide resin obtained by reacting a polyisocyanate having a biphenyl skeleton with an acid anhydride .   The heat-resistant coating material according to claim 1, wherein the polyimide resin (A) has a biphenyl skeleton content of 25 to 40% by mass and a logarithmic viscosity of 0.2 to 0.7 dl / g.   The heat-resistant paint according to claim 1, wherein the polyimide resin (A) is a polyimide resin having a weight average molecular weight of 5000 to 80000. The heat-resistant paint according to claim 1, wherein the epoxy resin (B) is an epoxy resin represented by the following formula.

In the formula, R is a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or a hydroxyphenyl group. )   The heat resistant paint according to claim 4, wherein R is a hydrogen atom.   Furthermore, the heat-resistant coating material of Claim 1 containing a sliding agent (C).   The heat-resistant paint according to claim 6, wherein the sliding agent (C) is graphite or molybdenum disulfide. Content of the said epoxy resin (B) is 10-100 mass parts with respect to 100 mass parts of said polyimide resins (A), and content of the said sliding agent (C) is a polyimide resin (A) and an epoxy resin. The heat-resistant paint according to claim 6, which is 0.5 to 50 parts by mass with respect to 100 parts by mass as a total of (B) . The heat-resistant paint according to claim 1, wherein the polyimide resin (A) is a polyimide resin further having a benzophenone structure. The heat-resistant paint according to claim 1 or 5, wherein the polyimide resin (A) is a polyimide resin further having a tolylene structure. The heat resistant paint according to claim 1, wherein the polyimide resin (A) is a polyimide resin having no alkylene structure. Claim 1, wherein the heat-resistant paint polyisocyanates are polyisocyanates derived from tolidine diisocyanate or tolidine diisocyanate having a biphenyl skeleton.   An article having a film formed by curing the heat-resistant paint according to any one of claims 1 to 12.