JP2011012220A - Low-temperature curing low-elastic modulus polyamideimide resin, polyamideimide resin composition, coating, and coating for coating sliding part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamideimide resin, a polyamideimide resin composition, and a coating, which can be cured at a low temperature, whose elastic modulus is made low, and whose adhesion to a substrate is hardly reduced by a large deformation of the substrate, so that these are used as a coating for a very flexible substrate such as a rubber.SOLUTION: The polyamideimide resin is obtained by reacting a mixture containing (a) a tricarboxylic acid derivative having an acid anhydride group, (b) a dicarboxylic acid represented by formula (I) wherein a+b+c is a real number of 1 to 80; Ris hydrogen or a methyl group; Ris a cyano group, a carboxyl group or the like, and (c) an aromatic polyisocyanate, wherein the component (a) and the component (b) are contained in such a blend proportion that the ratio (a)/(b) of the total number of the carboxyl group and the acid anhydride group in the component (a) and the total number of the carboxyl group in the component (b) is 0.45/0.55 to 0.80/0.20.

Description

  The present invention relates to a low-temperature curing low elastic modulus polyamideimide resin, a polyamideimide resin composition using the same, a paint, and a sliding part coating paint.

  Polyamideimide resins are excellent in heat resistance, chemical resistance and solvent resistance, and are therefore widely used as coating agents for various substrates, for example, enameled wire varnishes and heat resistant paints. However, curing of a paint using a polyamideimide resin usually requires heating at a high temperature of 250 ° C. or higher, and may cause a side reaction when an additive is blended. In addition, since general-purpose polyamideimide resin is hard, when applied to a base material such as a flexible resin such as rubber, there is a problem that the adhesiveness decreases due to deformation of the base material during processing or use. It was difficult. As a means to increase the flexibility of the polyamideimide resin, it has been proposed to introduce a polybutadiene or polyacrylonitrile structure into the polyamideimide resin skeleton, but it can also be used for a flexible resin such as rubber. Is not obtained (for example, refer to Patent Document 1).

JP 2006-348135 A

  The present invention retains the properties such as heat resistance of the polyamideimide resin and can be cured at a low temperature and has a low elastic modulus so that it can be used as a coating material for extremely flexible substrates such as rubber. It is an object of the present invention to provide a polyamide-imide resin, a polyamide-imide resin composition, a paint, and a sliding part coating paint that are less likely to deteriorate in adhesiveness even during large deformation during processing or use.

［式中、ａ、ｂ及びｃは各々独立に０〜８０の実数であり、ａ／ｂの比は１／０〜０／１であり、（ａ＋ｂ）／ｃの比は１／０〜０／１であり、ａ＋ｂ＋ｃは１〜８０の実数であり、Ｒ¹は水素又はメチル基を表し、Ｒ²はシアノ基、カルボキシル基、アミノ基、ヒドロキシル基、エポキシ基又はフェニル基を表し、Ｒ¹及びＲ²は、各々、１分子中に２種以上含まれていてもよい。］
で表されるジカルボン酸及び（ｃ）芳香族ポリイソシアネートの混合物であって、（ａ）成分と（ｂ）成分を、（ａ）成分のカルボキシル基及び酸無水物基の総数と（ｂ）成分のカルボキシル基の総数との比（ａ）／（ｂ）が０．４５／０．５５〜０．８０／０．２０である配合割合で含有する混合物を反応させて得られたポリアミドイミド樹脂に関する。 The present invention relates to (a) a derivative of a trivalent carboxylic acid having an acid anhydride group, (b) a general formula (I)

[Wherein, a, b and c are each independently a real number of 0 to 80, the ratio of a / b is 1/0 to 0/1, and the ratio of (a + b) / c is 1/0 to 0 /, A + b + c is a real number of 1 to 80, R ¹ represents hydrogen or a methyl group, R ² represents a cyano group, a carboxyl group, an amino group, a hydroxyl group, an epoxy group or a phenyl group, R ¹ And R ² may be contained in one molecule in two or more. ]
A mixture of a dicarboxylic acid represented by the formula (c) and an aromatic polyisocyanate, wherein the component (a) and the component (b) are combined with the total number of carboxyl groups and acid anhydride groups of the component (a) and the component (b). Relates to a polyamideimide resin obtained by reacting a mixture containing a mixture ratio of (a) / (b) to the total number of carboxyl groups of 0.45 / 0.55 to 0.80 / 0.20 .

In addition, the present invention provides the components (a), (b) and (c) as a ratio of the total number of carboxyl groups and acid anhydride groups of the component (a) to the total number of carboxyl groups of the component (b) ( a) / (b) is 0.5 / 0.5 to 0.8 / 0.2, the total number of carboxyl groups and acid anhydride groups of component (a) and component (b) and component (c) The ratio of the total number of isocyanate groups ((a) + (b)) / (c) is 1.0 / 0.9 to 1.0 / 1.3, and the component (b) The present invention relates to the above polyamideimide resin obtained by reacting a mixture in which R ¹ is H in the formula (I) and R ² is a cyano group or a carboxyl group.

  The present invention also relates to the above polyamideimide resin having a number average molecular weight of 9,000 to 90,000.

  Further, the present invention provides a polyamideimide resin composition containing 1 to 40 parts by weight of at least one selected from the group consisting of a polyfunctional epoxy resin, a polyisocyanate compound and a melamine compound with respect to 100 parts by weight of the above polyamideimide resin. Related to things.

  Moreover, this invention relates to the coating material containing said polyamideimide resin as a coating-film component.

  Moreover, this invention relates to the sliding part coating coating material which contains said polyamideimide resin as a coating-film component.

  Moreover, this invention relates to the coating material containing said polyamideimide resin composition as a coating-film component.

  Moreover, this invention relates to the sliding part coating coating material which contains said polyamideimide resin composition as a coating-film component.

  The polyamide-imide resin and the polyamide-imide resin composition of the present invention can be cured at a low temperature, have a low elastic modulus compared to conventional polyamide-imide resins and have excellent flexibility, and can be used when processing a substrate. Since the adhesiveness is not easily lowered by deformation at the time, it is suitably used as a coating material for a substrate having a large deformation, such as rubber or a soft resin, or a sliding coating material.

  Examples of the derivative of the trivalent carboxylic acid having an acid anhydride group used in the production of the polyamideimide resin of the present invention include trivalent carboxylic acid having an acid anhydride group that reacts with an isocyanate group or an amino group. There is no particular limitation as long as it is a derivative, but an aromatic tricarboxylic acid anhydride is preferable. For example, compounds represented by the general formulas (II) and (III) can be suitably used. In view of heat resistance, cost, etc., trimellitic anhydride is particularly preferable. These trivalent carboxylic acid derivatives having an acid anhydride group may be used alone or in admixture of two or more according to the purpose.

（ただし、両式中、Ｒ及びＲ′は水素、炭素数１〜１０のアルキル基又はフェニル基を示し、Ｙは−ＣＨ₂−、−ＣＯ−、−ＳＯ₂−、又は−Ｏ−を示す。）

(However, in both formulas, R and R ′ represent hydrogen, an alkyl group having 1 to 10 carbon atoms, or a phenyl group, and Y represents —CH ₂ —, —CO—, —SO ₂ —, or —O—. .)

  In addition to these, if necessary, tetracarboxylic dianhydride (pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4, 4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, 1,4,5,8 -Naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, m-terphenyl-3,3 ', 4 4'-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis (2,3- or 3,4 -Dicarboxyphenyl) propane dianhydride, 2,2 Bis (2,3- or 3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1 , 1,1,3,3,3-hexafluoro-2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1,3-bis (3 , 4-Dicarboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride, butanetetracarboxylic dianhydride, bicyclo- [2,2,2] -oct-7-ene-2: 3: 5: 6-tetracarboxylic dianhydride, etc.), aliphatic dicarboxylic acids (succinic acid, glutaric acid, adipic acid, azelaic acid, suberic acid, sebacic acid, decanedioic acid, dodecanedioic acid, dimer acid, etc.) , Aromatic dicarboxylic acids (I Phthalic acid, terephthalic acid, phthalic acid, naphthalene dicarboxylic acid, and oxydiphthalic acid) and the like, can be used together as part of component (a).

  In this invention, as dicarboxylic acid of (b) component, only 1 type of dicarboxylic acid represented by general formula (I) may be used independently, and 2 or more types may be used together.

  Examples of the dicarboxylic acid represented by the general formula (I) of the component (b) in the present invention include, for example, Nippon Soda Co., Ltd., Nisso-PB series, Ube Industries, Ltd. Hycar-RLP series (CTBN1300X9, etc.), Examples include the HC-polymer series manufactured by Thiokol, the Telagen series manufactured by General Tire, and the Butaretz series manufactured by Phillips Petroleum. These may be used alone or in combination depending on the purpose.

  In general formula (I), a + b + c is a real number of 1-80, preferably a real number of 5-70, more preferably a real number of 10-65. When a + b + c is 0, flexibility and softness are lowered. When a + b + c is more than 80, heat resistance and reactivity tend to be lowered. In the general formula (I), a / b is 1/0 to 0/1, preferably 1/0 to 0.2 / 0.8, and more preferably 1/0 to 0.4 / 0. 6. When a / b is 0/1, heat resistance tends to decrease. In general formula (I), (a + b) / c is 1/0 to 0/1, preferably 0.95 / 0.05 to 0.2 / 0.8, more preferably 0.9 / 0.1 to 0.4 / 0.6. When (a + b) / c is 0/1, heat resistance tends to decrease, and when 1/0, solubility and adhesion tend to decrease.

In the general formula (I), R ¹ and R ² are preferably R ¹ is hydrogen and R ² is a cyano group or a carboxyl group in consideration of the balance of adhesion, solubility, workability and cost. , R ¹ is hydrogen, and R ² is a cyano group (however, it may contain, for example, 0.1 equivalent% or less of a carboxyl group with respect to the total of the cyano group and the carboxyl group). More preferred.

  Examples of the aromatic polyisocyanate (c) in the present invention include 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 '-[2,2-bis (4-Phenoxyphenyl) propane] diisocyanate, biphenyl-4,4'-diisocyanate, biphenyl-3,3'-diisocyanate, biphenyl-3,4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'- Diisocyanate, 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'-diethylbiphenyl-4,4'-diisocyanate, 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3 '-Dimethoxybiphenyl 4,4'-diisocyanate, 2,2'-dimethoxy-biphenyl-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, can be used 2,6-diisocyanate. These can be used alone or in combination. Hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, transcyclohexane-1,4-diisocyanate, hydrogenated m-xylylene diene as part of this if necessary Aliphatic such as isocyanate and lysine diisocyanate, alicyclic isocyanate and trifunctional or higher polyisocyanate can also be used.

  Moreover, you may use what stabilized the isocyanate group with the blocking agent as needed in order to avoid a change over time. The blocking agent includes alcohol, phenol, oxime, etc., but there is no particular limitation.

  Considering the balance of heat resistance, solubility, mechanical properties, cost, etc., 4,4′-diphenylmethane diisocyanate is particularly preferable.

  Considering the solvent resistance of the film, toluene diisocyanate and 3,3′-dimethylbiphenyl-4,4′-diisocyanate are particularly preferable.

  The blending ratio (equivalent ratio) of the trivalent carboxylic acid derivative having an acid anhydride group of the component (a) and the dicarboxylic acid represented by the general formula (I) of the component (b) in the present invention, that is, ( The ratio (a) / (b) of the total number of carboxyl groups and acid anhydride groups in the component a) to the total number of carboxyl groups in the component (b) is 0.45 / 0.55-0.8 / 0.2. And preferably 0.5 / 0.5 to 0.8 / 0.2, more preferably 0.55 / 0.45 to 0.8 / 0.2, and 0.6 / It is especially preferable to set it as 0.4-0.7 / 0.3. If it exceeds 0.8 / 0.2, the elastic modulus does not decrease, and if it is less than 0.5 / 0.5, the reactivity of the resin synthesis may decrease, and it is less than 0.45 / 0.55. And the reactivity of resin synthesis is significantly reduced.

  The blending ratio of the aromatic polyisocyanate of component (c) is the ratio of the total number of carboxyl groups and acid anhydride groups of component (a) and component (b) to the total number of isocyanate groups of component (d), ((a ) + (B)) / (c) is preferably 1.0 / 0.9 to 1.0 / 1.3, 1.0 / 0.95 to 1.0 / 1. 2 is more preferable, 1.0 / 1.0 to 1.0 / 1.1 is still more preferable, and 1.0 / 1.02 to 1.0 / 1. It is particularly preferable that the value be 05. When the ratio of the isocyanate is slightly high, foaming occurs by absorbing moisture in the air at the time of curing, so that it is cured and becomes a sponge-like structure, and the rebound resilience is improved when the film is pushed.

  In order to further reduce the elastic modulus, a urethane bond can be introduced using a dihydric or higher alcohol or carbonate diol as a reaction raw material to obtain a more flexible resin. Examples of the carbonate diol include CD220 and CD220PL manufactured by Daicel Chemical Industries, Ltd., and examples of the alcohol include ethylene glycol.

The polyamideimide resin of the present invention is produced by reacting a mixture of the component (a), the component (b) and the component (c). The reaction method includes, for example, the following methods, but there is a particular limitation. Absent.
(1) A method in which all of the components (a), (b) and (c) are mixed at a time and reacted to obtain a polyamideimide resin.
(2) After reacting the component (b) with an excess amount of the component (c) to synthesize an amide-imide oligomer having an isocyanate group at the end, the component (a) and the remaining component (c) are added and reacted. To obtain a polyamide-imide resin.
(3) After an excess amount of the component (a) is reacted with a part of the component (c) to synthesize an amide-imide oligomer having an acid or acid anhydride group at the terminal, the component (b) and the remaining ( c) A method of adding a component and reacting to obtain a polyamideimide resin.
From the viewpoint of easy synthesis and high molecular weight, the method (1) is preferred.

  Reaction includes polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, γ-butyrolactone, aromatic hydrocarbon solvents such as xylene and toluene, methyl ethyl ketone, methyl isobutyl ketone, etc. It is carried out in a solvent such as ketones. Although there is no restriction | limiting in particular in the usage-amount of a solvent, It is preferable to set it as 50-500 weight part with respect to 100 weight part of total amounts of (a) component, (b) component, and (c) component. Although the reaction conditions cannot be generally specified, it is usually performed at a temperature of 80 to 150 ° C., and it is preferably performed under an inert atmosphere such as nitrogen in order to reduce the influence of moisture in the air.

  The polyamideimide resin thus obtained preferably has a number average molecular weight of 9,000 to 90,000. If the number average molecular weight is less than 9,000, the film-forming property tends to be poor when used as a paint, and if it exceeds 90,000, the viscosity increases when dissolved in a solvent at an appropriate concentration as a paint. The workability during painting tends to be inferior. From this, the number average molecular weight of the polyamideimide resin is more preferably 9,000 to 70,000, further preferably 12,000 to 40,000, and particularly preferably 16,000 to 27,000.

  The number average molecular weight of the polyamideimide resin is sampled at the time of resin synthesis, measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve, and the synthesis is continued until the target number average molecular weight is reached. By doing so, it is managed within the above range.

  The heat resistant resin composition which is the polyamideimide resin composition of the present invention contains at least one selected from the group consisting of a polyfunctional epoxy resin compound, a polyisocyanate compound and a melamine compound together with the polyamideimide resin. By blending these, it becomes difficult to foam when heated and cured, and curing in a shorter time becomes possible. The compounding amount of the polyfunctional epoxy resin compound is preferably 1 to 40 parts by weight with respect to 100 parts by weight of the polyamideimide resin, and the compounding amount of the polyisocyanate compound is 1 to 100 parts by weight of the polyamideimide resin. It is preferable to set it as 10 weight part, and it is preferable that the compounding quantity of a melamine compound shall be 0.5-20 weight part with respect to 100 weight part of polyamideimide resins. When the compounding amount of these compounds is less than the above preferable range, the effect of improving adhesion is reduced, and when the above preferable range is exceeded, the heat resistance of the coating film tends to be remarkably reduced, and the coating film strength is further reduced. There is a tendency to show.

  The polyfunctional epoxy compound is not particularly limited, such as bisphenol A type, bisphenol F type, novolac type, amine type, alcohol type, biphenyl type, ester type, etc., and generally known ones can be used. A plurality of compounds may be used at the same time, but the use of a bisphenol A type epoxy compound is particularly preferred from the viewpoint of reactivity with the polyamideimide resin of the present invention and storage stability of the paint.

  Examples of the polyisocyanate compound include Duranate TKA-100 (trade name, manufactured by Asahi Kasei Chemicals Corporation), Dismodule TT (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), and Dismodule IL (Sumitomo Bayer Urethane Co., Ltd.). Product, trade name), polyisocyanate obtained by reacting diaminodiphenylmethane with an alcohol such as glycerin, etc. There is no particular limitation, and generally known ones can be used. You may use together.

  The melamine compound is not particularly limited, for example, Cymel 303, 325, 327, 350, 370 (trade name, manufactured by Mitsui Cytec Co., Ltd.), and generally known ones can be used. Alternatively, a plurality of things may be used in combination.

  The polyamide-imide resin and resin composition of the present invention include polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, and γ-butyrolactone, and aromatic carbonization such as xylene and toluene. It can be dissolved in a solvent such as hydrogen solvent, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and adjusted to an appropriate viscosity to obtain a coating material. In the case of a paint, the solid content is generally 10 to 50% by weight. The viscosity of the paint is preferably 1 to 30 Pa · s at 25 ° C., more preferably 2 to 20 Pa · s.

  Moreover, the coating material of this invention may contain additives, such as a coloring agent, in addition to the polyamideimide resin or polyamideimide resin composition and solvent of this invention. Examples of the colorant include indigo carmine, acid red, tartrazine, anthocyanin dye, caramel dye, anato dye, amaranth, erythromine, flavonoid dye, brilliant blue FCF, and the like.

  The sliding part coating film component of the present invention contains the polyamideimide resin or the polyamideimide resin composition of the present invention as a coating film component, and in addition to the solvent, if necessary, the above-mentioned additives for paints It is preferable to contain a solid lubricant. Examples of solid lubricants include sulfides, fluorine compounds, graphite, and the like, and these can be used alone or in combination of two or more, and are preferably used as fine powders.

  Examples of the sulfide used as the solid lubricant include molybdenum disulfide and tungsten disulfide. Examples of the fluorine compound include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexa. Examples include fluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, polyvinylidene fluoride, and trichlorotrifluoroethylene.

  The blending amount of the solid lubricant is preferably 1 to 100 parts by weight and more preferably 10 to 50 parts by weight with respect to 100 parts by weight of the polyamideimide resin or the polyamideimide resin composition of the present invention.

  Moreover, you may mix | blend an antiwear material with the sliding part coating-film component of this invention as needed. Examples of the wear-resistant material include silicon nitride, silicon carbide, boron nitride, alumina, silica, silicate glass, diamond and the like, and these are preferably used as fine powders.

  When blending the wear-resistant material, the blending amount of the wear-resistant material is preferably 1 to 100 parts by weight, and 10 to 50 parts by weight with respect to 100 parts by weight of the polyamide-imide resin or the polyamide-imide resin composition of the present invention. More preferably.

  The paint containing the polyamideimide resin or the polyamideimide resin composition of the present invention as a coating film component and the sliding part coating film component form a coating film on the surface of the object to be coated by applying and curing the object. . A paint containing a normal polyamide-imide resin or a polyamide-imide resin composition as a coating film component is heat-treated for drying and curing and needs to be heated at least at 230 ° C. for 20 minutes. This is because, when cured at a low temperature, the solvent remains, and the coating properties that protect the substrate may be inferior. In addition, a coating material containing a normal polyamideimide resin or a polyamideimide resin composition as a coating film component is not sufficiently cured when cured at a temperature of less than 230 ° C. and is dissolved or swollen in a polar solvent. there's a possibility that. The coating material containing the polyamideimide resin or the polyamideimide resin composition of the present invention as a coating film component can be dried and cured by heating at 160 to 220 ° C. for 20 to 60 minutes. If the heating time is less than 20 minutes, the residual solvent may remain on the coating film, and the properties of the coating film applied to the substrate may be inferior. If the heating time exceeds 60 minutes, a solid lubricant is applied by applying heat for a long time. In the case of a paint to which etc. are added, a side reaction may occur and the properties of the coating film may be deteriorated.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

[Example 1]
A 2 liter four-necked flask equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer was added 134.5 g (0.70 mol) trimellitic anhydride, CTBN1300X13 [trade name, general formula (I A + b + c = 63, a / b = 1/0, (a + b) /c=0.83/0.17, R ¹ = H, R ² = -CN (slightly -COOH is bonded. 0.06 equivalent% of carboxyl groups)]] 1050 g (0.30 mol), 4,4'-diphenylmethane diisocyanate 255.8 g (1.023 mol), N-methyl-2- Pyrrolidone (2152.2 g) was charged, heated to 120 ° C., and reacted for about 5 hours to obtain a polyamideimide resin solution having a viscosity of 3.5 Pa · s (viscosity was measured with a B-type viscometer at 25 ° C. It was. Hereinafter the same). The number average molecular weight of the polyamideimide resin was 18000.

[Example 2]
In a 2 liter four-necked flask equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 96.1 g (0.50 mol) of trimellitic anhydride, 1750 g (0.50 mol) of CTBN1300X13, 4,4′- Diphenylmethane diisocyanate 262.8 g (1.05 mol) and N-methyl-2-pyrrolidone 3144.6 g were charged and reacted at 130 ° C. for 5 hours to obtain a polyamideimide resin solution having a viscosity of 2.8 Pa · s. The number average molecular weight of the polyamideimide resin was 17000.

[Example 3]
In a 3 liter four-necked flask equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 111.3 g (0.58 mol) of trimellitic anhydride, 1400 g (0.40 mol) of CTBN1300X13, 4,4′- 125.2 g (0.5 mol) of diphenylmethane diisocyanate, 86.1 g (0.49 mol) of a mixture of 2,6-toluene diisocyanate and 2,4-toluene diisocyanate (TDI), N-methyl-2-pyrrolidone 2589. 3 g was charged and reacted at 130 ° C. for 4 hours to obtain a polyamideimide solution having a viscosity of 6.4 Pa · s. The number average molecular weight of the polyamideimide resin was 18000.

[Example 4]
In a 3 liter four-necked flask equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 111.3 g (0.58 mol) of trimellitic anhydride, 1400 g (0.40 mol) of CTBN1300X13, 4,4′- 175.1 g (0.70 mol) of diphenylmethane diisocyanate, 57.5 g (0.33 mol) of a mixture of 2,6-toluene diisocyanate and 2,4-toluene diisocyanate (TDI), N-methyl-2-pyrrolidone 2589. 3 g was charged and reacted at 130 ° C. for 4 hours to obtain a polyamideimide solution having a viscosity of 4.9 Pa · s. The number average molecular weight of the polyamideimide resin was 18000.

Comparative Example 1
In a 2 liter four-necked flask equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 192.1 g of trimellitic anhydride, 250.3 g of 4,4′-diphenylmethane diisocyanate and 663.6 g of N-methyl-2-pyrrolidone Was heated to 130 ° C. and reacted for 4 hours to obtain a polyamideimide resin solution having a viscosity of 2.9 Pa · s. The number average molecular weight of the polyamideimide resin was 18000.

Comparative Example 2
In a 2 liter four-necked flask equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 134.5 g of trimellitic anhydride, 60.7 g of sebacic acid, 250.3 of 4,4'-diphenylmethane diisocyanate and N-methyl- 2-Pyrrolidone 668.3 g was charged, heated to 130 ° C., and reacted for 5 hours to obtain a polyamideimide resin solution having a viscosity of 3.1 Pa · s. The number average molecular weight of the polyamideimide resin was 18,700.

The evaluation shown in the examples was measured by the following method.
(1) Appearance: A polyamideimide resin solution was applied on a glass plate to a thickness of 20 ± 5 μm, then heat-treated at 200 ° C. for 30 minutes, and visually checked for turbidity of the coating film and surface roughness.
(2) Mechanical properties: A film obtained by applying a polyamideimide resin solution to a glass plate and heating is adjusted to a film thickness of 20 μm, a width of 10 mm, and a distance between chucks of 20 mm. Tensile tests were performed, and tensile strength, elastic modulus, and elongation were measured.
(3) Adhesion (cross-cut test): After applying a polyamideimide resin solution on an aluminum plate (A1050P) to a thickness of 20 μm, heat treatment was performed at 200 ° C. for 30 minutes, and the obtained coating film was subjected to JIS D0202. The test was carried out accordingly.
(4) Pencil hardness: A polyamideimide resin solution was applied on an aluminum plate (A1050P) to a thickness of 20 μm, then heat-treated at 200 ° C. for 30 minutes, and the obtained coating film was tested according to JIS K5600. It was.
(5) Curability: The polyamideimide resin solution was applied on a 20 × 50 mm steel plate so as to have a film thickness of 20 μm, and then heat treated at 200 ° C. for 30 minutes. After immersing this in N-methyl-2-pyrrolidone for 1 hour, the extraction rate was calculated from the following formula. In addition, drying after immersion of the coating film was performed by heat treatment at 100 ° C. for 5 minutes.
Extraction rate = [1- (weight of dried coating film after immersion / weight of dried coating film before immersion)] × 100%

  From the results shown in Table 1, it can be seen that the polyamideimide resin compositions obtained in the examples of the present invention have excellent adhesion even when cured at low temperature, and have a low extraction rate and excellent low temperature curability. . Although the examples are inferior to Comparative Examples 1 and 2 in the hardness and tensile strength of the coating film, the polyamideimide resins obtained in Examples 1, 2, and 3 are more than the polyamideimide resins obtained in Comparative Examples 1 and 2. Since the elastic modulus is low and the elongation is large, it can be seen that the film has excellent flexibility.

Claims (8)

(A) a derivative of a trivalent carboxylic acid having an acid anhydride group, (b) a general formula (I)

[Wherein, a, b and c are each independently a real number of 0 to 80, the ratio of a / b is 1/0 to 0/1, and the ratio of (a + b) / c is 1/0 to 0 /, A + b + c is a real number from 1 to 80, R ¹ represents hydrogen or a methyl group, R ² represents a cyano group, a carboxyl group, an amino group, a hydroxyl group, an epoxy group or a phenyl group, R ¹ And R ² may be contained in one molecule in two or more. ]
A mixture of a dicarboxylic acid represented by the formula (c) and an aromatic polyisocyanate, wherein the component (a) and the component (b) are combined with the total number of carboxyl groups and acid anhydride groups of the component (a) and the component (b). A polyamide-imide resin obtained by reacting a mixture containing a ratio of (a) / (b) to the total number of carboxyl groups of 0.45 / 0.55 to 0.80 / 0.20. Component (a), Component (b) and Component (c) are the ratio of the total number of carboxyl groups and anhydride groups in component (a) to the total number of carboxyl groups in component (b) (a) / (b) 0.5 / 0.5 to 0.8 / 0.2, and the total number of carboxyl groups and acid anhydride groups of component (a) and component (b) and the total number of isocyanate groups of component (c) The ratio ((a) + (b)) / (c) is contained at a blending ratio of 1.0 / 0.9 to 1.0 / 1.3, and the formula (I) of the component (b) The polyamide-imide resin according to claim 1 obtained by reacting a mixture in which R ¹ is H and R ² is a cyano group or a carboxyl group.   The polyamideimide resin according to claim 1 or 2, which has a number average molecular weight of 9,000 to 90,000.   Polyamideimide containing 1 to 40 parts by weight of at least one selected from the group consisting of a polyfunctional epoxy resin, a polyisocyanate compound and a melamine compound with respect to 100 parts by weight of the polyamideimide resin according to any one of claims 1 to 3. Resin composition.   The coating material which contains the polyamide-imide resin in any one of Claims 1-3 as a coating-film component.   The sliding part coating coating material which contains the polyamideimide resin in any one of Claims 1-3 as a coating-film component.   A paint containing the polyamideimide resin composition according to claim 4 as a coating film component.   The sliding part coating coating material which contains the polyamide-imide resin composition of Claim 4 as a coating-film component.