KR102533436B1 - Urethane-modified polyimide-based resin solution - Google Patents

Abstract

An object of the present invention is to provide a novel urethane-modified polyimide-based resin solution that does not use any polar solvent having a high boiling point and high hygroscopicity.
When the total constituents of the urethane-modified polyimide-based resin (A) are 100 mol%, 30 to 90 mol% of the amideimide unit (i) composed of trimellitic acid derivatives and aromatic diisocyanate components, a compound having a specific structure A urethane-modified polyimide-based resin (A) containing 10 to 70 mol% of a urethane unit (ii) composed of an aromatic diisocyanate component, and at least one organic solvent selected from the group consisting of cyclohexanone and cyclopentanone (B ) Urethane-modified polyimide-based resin solution containing.

Description

Urethane-modified polyimide-based resin solution

The present invention maintains the inherent heat resistance, mechanical properties, metal adhesion, and chemical resistance of polyamide-imide resin, and is excellent in low-temperature drying property, moisture absorption stability, and storage stability, and is soluble in non-amide-based solvents and forms a flexible film. It relates to a urethane-modified polyimide-based resin and a method for producing the same. In particular, it relates to a urethane-modified polyimide-based resin useful as an inner surface paint for aerosol cans having excellent heat resistance, chemical resistance, and bending workability, or as a binder for screen printing inks for electronic materials, and a method for producing the same.

Conventionally, since polyamideimide resins are excellent in heat resistance, chemical resistance, and solvent resistance, they are widely used as coating agents for various substrates, such as varnishes for enamel wires, heat-resistant paints, and the like. However, since conventional polyamideimide resins have a hard coating due to their structure, application to applications requiring flexibility and limited drying temperature, such as paints and adhesives requiring bending and the like, has been difficult. In addition, conventional polyamideimide resins are solvents with high boiling points and high hygroscopicity, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), and γ-butyrolactone (GBL). Since it is dissolved in, special environmental maintenance is required, or it is necessary to heat to a high temperature of 250 ° C. or higher in order to express the above characteristics, so processing facilities and base materials are limited, and there are problems such as high cost.

First, regarding the problem of flexibility, copolymerization of long-chain monomers or oligomers has conventionally been studied in order to improve the flexibility of polyimide-based resins. For example, studies on polysiloxane-modified polyimide-based resins (Patent Documents 1 and 2) and studies on dimer acid copolymerized polyamideimide resins (Patent Document 3) have been proposed, but polysiloxanes are expensive and dimer acids have a low molecular weight. In order to obtain sufficient flexibility, a large amount of copolymerization is required, and there has been a problem that the inherent heat resistance of the polyimide-based resin is impaired.

On the other hand, since the conventional polyamideimide resin is polymerized with a solvent with a high boiling point and high hygroscopicity such as NMP or DMAc, when the polymerization solution is used as it is for paints or adhesives, it is necessary to dry at a high temperature of 250 ° C. or higher. Regarding problems such as poor productivity or inapplicability to applications other than metals, a technique of dissolving polyamide-imide resin in a low-boiling solvent has also been studied, for example, a solution obtained by polymerizing polyamide-imide resin in NMP or GBL. A method (Patent Document 4) has been proposed in which a coagulated polymer obtained by injecting into a poor solvent such as water is dried and then dissolved again in a low boiling point solvent such as alcohol or ether, but it is expensive due to many manufacturing steps.

In addition, attempts have been made to improve productivity and workability by polymerization in a cyclic ketone solvent as a non-amide-based low-boiling solvent (Patent Document 5), but in most cases, polymerization is performed in combination with NMP, so sufficient effect is not seen, and NMP Even if it is not used, it becomes a polyamide-imide resin with many aromatic constituents in order to maintain heat resistance. As a result, the solubility is unstable, the storage stability is poor, and since a high molecular weight body cannot be obtained, the film becomes brittle.

On the other hand, conventionally, epoxy resins, phenol resins, and the like are mainly used as a paint for the inner surface of a metal can, which is one of the objects of the present invention. Due to the diversification of contents in recent years, polyamide-imide resins have been partially employed due to the demand for acid resistance, alkali resistance, and durability to various organic solvents. However, conventional polyamideimide resins cannot meet the requirements for bending workability, workability, environmental performance and productivity in the can manufacturing process for the reasons described above, and thus their applications have been limited.

Patent Document 1: Japanese Unexamined Patent Publication No. Heisei 5-25452 Patent Document 2: Japanese Unexamined Patent Publication No. Heisei 7-304950 Patent Document 3: Japanese Patent Publication No. 3-54690 Patent Document 4: Japanese Patent No. 3446845 Patent Document 5: Japanese Unexamined Patent Publication No. 2011-187262

As can be seen from these examples, in the prior art so far, polyimide-based resins that are synthesized in low-boiling non-amide-based solvents, have excellent low-temperature drying properties, workability, and productivity, and form flexible, heat-resistant coatings. There was no The present invention solves the problems of the prior art and develops a urethane-modified polyimide-based resin that does not use a polar solvent with a high boiling point and high hygroscopicity at all, and is excellent in low-temperature drying property, workability, productivity, and polyimide It is an object to provide a novel urethane-modified polyimide-based resin solution that is flexible and has excellent flexibility while maintaining the original heat resistance, adhesion, and chemical resistance of the base resin.

The present inventors came to complete this invention as a result of earnest research to solve the said subject. That is, this invention consists of the following structures.

When the total components of the urethane-modified polyimide-based resin (A) are 100 mol%, 30 to 90 mol% of the amideimide unit (i) composed of a trimellitic acid derivative and an aromatic diisocyanate component, the general formula (1 ) and a urethane-modified polyimide-based resin (A) containing 10 to 70 mol% of a urethane unit (ii) composed of an aromatic diisocyanate component, cyclohexanone, and cyclopentanone selected from the group consisting of A urethane-modified polyimide-based resin solution containing the above organic solvent (B).

(In general formula (1), m and n are integers greater than or equal to 1, and may be the same or different.)

It is preferable that the urethane-modified polyimide-based resin (A) further contains an imide unit (iii) composed of a tetravalent polycarboxylic acid derivative and an aromatic diisocyanate component.

It is preferable that the tetravalent polycarboxylic acid derivative is an alkylene glycol bisanhydrotrimellitate.

It is preferable that the tetravalent polycarboxylic acid derivative is ethylene glycol bisanhydrotrimellitate.

It is preferable to further contain a urethane unit (iv) composed of a polyalkylene glycol component and an aromatic diisocyanate component in the urethane-modified polyimide-based resin (A).

It is preferable that the polyalkylene glycol component is polytetramethylene glycol and/or polypropylene glycol.

A composition for painting the inner surface of a metal can or a screen printing ink containing at least one compound selected from the group consisting of polyfunctional epoxy compounds, amino resins, polyfunctional isocyanate compounds and polyfunctional phenol resins in the urethane-modified polyamideimide resin solution. composition for.

A paint for the inner surface of a metal can or an ink for screen printing, characterized in that the composition is mixed with inorganic and/or organic fine particles.

A trimellitic acid derivative and an aromatic compound obtained by polymerizing a trimellitic acid derivative, a compound represented by formula (1) and an aromatic diisocyanate in at least one organic solvent (B) selected from the group consisting of cyclohexanone and cyclopentanone A urethane-modified polyi containing 30 to 90 mol% of an amideimide unit (i) composed of diisocyanate and 10 to 70 mol% of a urethane unit (ii) composed of a compound represented by the general formula (1) and an aromatic diisocyanate Method for producing mead-based resin (A).

(In general formula (1), m and n are integers greater than or equal to 1, and may be the same or different.)

Since the urethane-modified polyimide-based resin solution of the present invention does not use any polar solvent with a high boiling point and high hygroscopicity and dissolves in a non-amide-based solvent with a low boiling point, it is excellent in drying property, workability, and productivity, and also polyimide It is flexible and has excellent flexibility while maintaining the original heat resistance, adhesiveness, and chemical resistance of the resin.

Hereinafter, the present invention will be described in detail.

<Urethane-modified polyimide-based resin (A)>

The urethane-modified polyimide-based resin (A) used in the present invention comprises an amideimide unit (i) composed of a trimellitic acid derivative and an aromatic diisocyanate component "hereinafter also referred to as an amideimide unit (i)", and a general formula ( It is a resin containing a urethane unit (ii) composed of the compound represented by 1) and an aromatic diisocyanate component "hereinafter also referred to as urethane unit (ii)". Preferably it is a urethane-modified polyamideimide resin.

In the general formula (1), m and n are each an integer greater than or equal to 1, and may be the same or different. The upper limits of m and n are not particularly limited, but are preferably 3 or less industrially, more preferably 2 or less, still more preferably 1.

When all constituents (all units) of the urethane-modified polyimide-based resin (A) are 100 mol%, the content of the amideimide unit (i) is required to be 30 mol% or more, preferably 35 mol% or more , More preferably, it is 40 mol% or more. Moreover, it is necessary that it is 90 mol% or less, Preferably it is 85 mol% or less, More preferably, it is 80 mol% or less. When the amideimide unit (i) is less than 30 mol%, the solubility and flexibility of the film are excellent, but the polymerization reaction becomes difficult to proceed, and the heat resistance, chemical resistance, and mechanical properties of the obtained urethane-modified polyimide-based resin may decrease. . When the amideimide unit (i) exceeds 90 mol%, the solubility of the urethane-modified polyimide-based resin decreases, so that the resin precipitates during polymerization, or the storage stability of the obtained resin solution is poor, and there is a risk that the resin precipitates over time. . Also, the obtained polyimide-based resin is brittle and lacks flexibility in some cases.

When all constituents (all units) of the urethane-modified polyimide-based resin (A) are 100 mol%, the content of the urethane unit (ii) is required to be 10 mol% or more, preferably 15 mol% or more, More preferably, it is 20 mol% or more. Moreover, it is necessary that it is 70 mol% or less, Preferably it is 65 mol% or less, More preferably, it is 60 mol% or less. If the content of the urethane unit (ii) is less than 10 mol%, the solubility of the polyimide-based resin is lowered, so there is a risk that the resin precipitates during polymerization or the storage stability of the obtained resin solution is poor, and the resin precipitates over time. Also, the obtained urethane-modified polyimide-based resin is brittle and lacks flexibility in some cases. When the urethane unit (ii) exceeds 70 mol%, the solubility in the solvent and the flexibility of the film are improved, but the polymerization reaction becomes difficult to proceed, and the heat resistance, chemical resistance, and mechanical properties of the obtained urethane-modified polyimide-based resin are lowered. there is

By satisfying the above range, the solubility of the urethane-modified polyimide-based resin (A) in cyclohexanone or cyclopentanone is improved, and it can be copolymerized as a component imparting flexibility without impairing heat resistance.

The greatest feature of the urethane-modified polyimide-based resin (A) is that it can be produced in at least one organic solvent selected from the group consisting of cyclohexanone and cyclopentanone having a low boiling point and low hygroscopicity. In addition, the prepared urethane-modified polyimide-based resin (A) has excellent heat resistance and mechanical properties and excellent chemical resistance while forming a flexible film, so it is suitably used as a paint for the inner surface of a pharmaceutical can or ink for screen printing.

The method for producing the urethane-modified polyimide-based resin (A) is not particularly limited, but a trimellitic acid derivative constituting the amideimide unit (i), an aromatic diisocyanate component, and a general constituting urethane unit (ii) described later. The compound represented by formula (1), an aromatic diisocyanate component, and optionally a tetravalent polycarboxylic acid derivative constituting the imide unit (iii), an aromatic diisocyanate component, and a polyalkyl constituting the urethane unit (iv) A method of dissolving len glycol and aromatic diisocyanate components in cyclohexanone and/or cyclopentanone alone or in a mixed solvent, heating and stirring at 60 ° C to 150 ° C, and polymerizing while removing carbon dioxide gas generated by the reaction can be heard In this case, each component may be added collectively from the beginning, or a polyamideimide prepolymer may be synthesized from a polycarboxylic acid component and a diisocyanate component, and then a glycol component may be introduced to introduce a urethane bond. Conversely, after forming the urethane prepolymer, you may form polyamideimide. However, in order to suppress the side reaction between polycarboxylic acid and glycol, which is a concern when synthesizing the urethane-modified polyimide-based resin (A) of the present invention, and to produce the target urethane-modified polyimide-based resin (A) with good reproducibility, It is preferable to initially form polyurethane by reacting some or all of the diisocyanate component with the glycol component, and then add the polycarboxylic acid component and react with the remaining diisocyanate component to form polyamideimide.

The molar ratio of the diisocyanate component at the time of synthesizing the urethane-modified polyimide-based resin (A) is preferably 0.8 to 1.1 with respect to the total of the acid component and glycol component reacting therewith. This is because when the molar ratio of the diisocyanate component is less than 0.8, the attained molecular weight is low and the film formed may become brittle.

As a solvent in synthesizing the urethane-modified polyimide-based resin (A), it is necessary to use at least one selected from the group consisting of cyclohexanone and cyclopentanone. It is preferable that at least one selected from the group consisting of cyclohexanone and cyclopentanone is contained in an amount of 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, in all solvents. , particularly preferably 100% by mass.

In the present invention, other solvents may be mixed and used within a range not impairing the object of the present invention. For example, hydrocarbon solvents such as xylene and toluene, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ether solvents such as tetrahydrofuran and dioxane, methanol, ethanol, isopropyl alcohol, butyl alcohol, etc. alcohol-based solvents, and the like, and these solvents may be added at any time at the beginning of polymerization, in the middle, or after completion of polymerization, all at once or in divided portions.

The amount of solvent used is preferably 0.8 to 5.0 times (mass ratio), more preferably 0.9 to 3.0 times the amount of the urethane-modified polyimide resin (A) to be produced. When it is less than 0.8 times, the viscosity at the time of synthesis is too high and synthesis tends to be difficult due to inability to stir, and when it exceeds 5.0 times, the reaction rate tends to decrease.

In the present invention, triethylamine, lutidine, picoline, undecene, triethylenediamine (1,4-diazabicyclo [2.2.2] octane), DBU (1,8-diazabicyclo amines such as [5.4.0]-7-undecene), alkali metals and alkaline earth metal compounds such as lithium methylate, sodium methylate, sodium ethylate, potassium butoxide, potassium fluoride and sodium fluoride, or titanium, cobalt, It may be carried out in the presence of a catalyst such as a metal such as tin, zinc, or aluminum, or a semimetal compound.

Further, the structural unit having a bisphenol skeleton is preferably 5 mol% or less, more preferably 1 mol% or less, when all constituents (all units) of the urethane-modified polyimide-based resin (A) are 100 mol%. and more preferably 0 mol%.

<Amidimide unit (i)>

The amideimide unit (i) used in the present invention is a unit composed of a trimellitic acid derivative and an aromatic diisocyanate component. Preferably, it is a polyamideimide unit synthesized by a conventional isocyanate method using a trimellitic acid derivative and an aromatic diisocyanate component as main constituents.

The trimellitic acid derivative is a trimellitic acid derivative, and specifically includes trimellitic acid and trimellitic acid anhydride. Preferred is trimellitic anhydride.

Although it does not specifically limit as an aromatic diisocyanate component, Specifically, as a polyisocyanate, for example, diphenylmethane 2,4'- diisocyanate, 3,2'- or 3,3'-, or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3, 3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-diethyldiphenylmethane-2,4'- Diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'- Dimethoxydiphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, Diphenyl ether-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2, 6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-[2,2bis(4-phenoxyphenyl)propane]diisocyanate, 3,3' or 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'- or 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3' -Dimethoxybiphenyl-4,4'-diisocyanate, 3,3'-diethoxybiphenyl-4,4'-diisocyanate, etc. are mentioned. Considering heat resistance, solubility, cost, etc., diphenylmethane-4,4'-diisocyanate, tolylene-2,4-diisocyanate, m-xylylenediisocyanate, 3,3' or 2,2'- Dimethylbiphenyl-4,4'-diisocyanate is preferable, and diphenylmethane-4,4'-diisocyanate and tolylene-2,4-diisocyanate are more preferable. These can be used individually or in combination of 2 or more types.

In the present invention, in addition to aromatic diisocyanates, aliphatic diisocyanates and alicyclic diisocyanates can be used, but in order to achieve the object of the present invention, it is preferable to use aromatic diisocyanates as a main component, and it is more preferable to use only aromatic diisocyanates. do.

Examples of the aliphatic diisocyanate component include hexamethylene diisocyanate and lysine diisocyanate, and examples of the alicyclic diisocyanate component include isophorone diisocyanate, dicyclohexylmethane diisocyanate, and transcyclohexane 1,4-diisocyanate.

<Urethane unit (ii)>

The urethane unit (ii) used in the present invention is a unit composed of a compound represented by general formula (1) and an aromatic diisocyanate component. Preferably, it is a polyurethane unit synthesized by a normal urethane reaction using a compound represented by the general formula (1) and an aromatic diisocyanate component as main constituents.

m and n in General formula (1) are synonymous with the above.

The compound represented by the general formula (1) is preferably tricyclodecane dimethanol (hereinafter also referred to as TCD-DM). By using tricyclodecane dimethanol, the solubility of the urethane-modified polyimide-based resin in cyclohexanone or cyclopentanone is improved, and flexibility can be imparted without impairing heat resistance. Among them, from the viewpoint of availability, tricyclo[5.2.1.0(2,6)]decane dimethanol is more preferable.

The aromatic diisocyanate component is preferably the same as the aromatic diisocyanate used in the amideimide unit (i). Further, in addition to aromatic diisocyanates, aliphatic diisocyanates and alicyclic diisocyanates can be used, but in order to achieve the object of the present invention, it is preferable to use aromatic diisocyanates mainly, and it is more preferable to use only aromatic diisocyanates.

Examples of the aliphatic diisocyanate component include hexamethylene diisocyanate and lysine diisocyanate, and examples of the alicyclic diisocyanate component include isophorone diisocyanate, dicyclohexylmethane diisocyanate, and transcyclohexane 1,4-diisocyanate.

<Imide unit (iii)>

The urethane-modified polyimide-based resin (A) used in the present invention may further contain an imide unit (iii) as needed. The imide unit (iii) is an imide unit composed of a tetravalent polycarboxylic acid derivative and an aromatic diisocyanate component.

The tetravalent polycarboxylic acid derivative is not particularly limited, but includes tetravalent aromatic polycarboxylic acids, tetravalent aliphatic polycarboxylic acids, tetravalent alicyclic polycarboxylic acids, and acid anhydrides or acid dianhydrides thereof. .

Aromatic polycarboxylic acid derivatives such as pyromellitic dianhydride, ethylene glycol bisanhydrotrimellitate, propylene glycol bisanhydrotrimellitate, 1,4-butanediol bisanhydrotrimellitate, hexamethylene glycol bis Alkylene glycol bisanhydrotrimellitate such as anhydrotrimellitate, polyethylene glycol bisanhydrotrimellitate, polypropylene glycol bisanhydrotrimellitate, 3,3',4,4'-benzophenonetetracar Boxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid Anhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfotetracarboxylic acid Anhydride, 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]propanedianhydride, 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, etc. can be heard

As the aliphatic polycarboxylic acid derivative or alicyclic polycarboxylic acid derivative, for example, butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, Cyclobutanetetracarboxylic dianhydride, hexahydropyromellitic dianhydride, cyclohexa-1-ene-2,3,5,6-tetracarboxylic dianhydride, 3-ethylcyclohexa-1-en-3-( 1,2),5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3-(1,2),5,6-tetracarboxylic dianhydride, 1-methyl-3-ethyl Cyclohexa-1-ene-3-(1,2),5,6-tetracarboxylic dianhydride, 1-ethylcyclohexane-1-(1,2),3,4-tetracarboxylic dianhydride, 1 -Propylcyclohexane-1-(2,3),3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane-1-(2,3),3-(2,3)-tetracar boxylic acid dianhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propyl Cyclohexane-1-(2,3),3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane-1-(2,3),3-(2,3)-tetracarboxylic acid Anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2. 2]octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]oct--7-ene-2,3,5,6-tetracarboxylic dianhydride, hexahydrotrimelli Tric acid anhydride etc. are mentioned.

These tetravalent polycarboxylic acid derivatives may be used alone or in combination of two or more. Considering heat resistance, adhesion to metal, solubility in cyclohexanone or cyclopentanone, cost, etc., pyromellitic dianhydride, ethylene glycol bisanhydrotrimellitate, 3,3',4,4'- Benzophenone tetracarboxylic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride are preferable, and among these, ethylene glycol bisanhydrotrimellitate is more preferable.

The aromatic diisocyanate component is preferably the same as the aromatic diisocyanate used in the amideimide unit (i). Further, in addition to aromatic diisocyanates, aliphatic diisocyanates and alicyclic diisocyanates can be used, but in order to achieve the object of the present invention, it is preferable to use aromatic diisocyanates mainly, and it is more preferable to use only aromatic diisocyanates.

Examples of the aliphatic diisocyanate component include hexamethylene diisocyanate and lysine diisocyanate, and examples of the alicyclic diisocyanate component include isophorone diisocyanate, dicyclohexylmethane diisocyanate, and transcyclohexane 1,4-diisocyanate. .

The content in the case of containing the imide unit (iii) is preferably 10 mol% or more, more preferably 10 mol% or more based on 100 mol% of all constituent components (all units) of the urethane-modified polyimide-based resin (A). is 20 mol% or more and preferably 60 mol% or less, more preferably 50 mol% or less, still more preferably 40 mol% or less. If it exceeds 60 mol%, the solvent solubility of the urethane-modified polyimide-based resin decreases, so that the resin precipitates during polymerization, or the storage stability of the obtained urethane-modified polyimide-based resin solution is poor, and there is a risk that the resin may precipitate over time. . Also, the obtained urethane-modified polyimide-based resin is brittle and lacks flexibility in some cases.

<Urethane unit (iv)>

The urethane-modified polyimide-based resin (A) used in the present invention may further contain a urethane unit (iv) as required. The urethane unit (iv) is a unit of urethane composed of a polyalkylene glycol component and an aromatic diisocyanate component.

Although it does not specifically limit as a polyalkylene glycol component, For example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly(neopentyl glycol/tetramethylene glycol) etc. are mentioned. The polyalkylene glycol component is copolymerized as a flexible component that imparts flexibility, bending characteristics, solubility and the like to the urethane-modified polyimide-based resin. Copolymerization of the polyalkylene glycol component can be expected to reduce the elastic modulus of the resin, improve the solubility in cyclohexanone or cyclopentanone solvents used as polymerization solvents, and increase the storage stability of the varnish.

As the polyalkylene glycol component, polytetramethylene glycol having a number average molecular weight of 500 or more and 3000 or less is preferably used, and more preferably 800 or more and 2000 or less polytetramethylene glycol. If the molecular weight is less than 500, heat resistance, flexibility and bending properties may be reduced, and if it is larger than 3000, the polymerization reaction is difficult to proceed and the solubility may be reduced.

The aromatic diisocyanate component is preferably the same as the aromatic diisocyanate used for the amideimide unit (i). Further, in addition to aromatic diisocyanates, aliphatic diisocyanates and alicyclic diisocyanates can be used, but in order to achieve the object of the present invention, it is preferable to use aromatic diisocyanates mainly, and it is more preferable to use only aromatic diisocyanates.

Examples of the aliphatic diisocyanate component include hexamethylene diisocyanate and lysine diisocyanate, and examples of the alicyclic diisocyanate component include isophorone diisocyanate, dicyclohexylmethane diisocyanate, and transcyclohexane 1,4-diisocyanate. .

The content in the case of containing the urethane unit (iv) is preferably 50 mol% or less, more preferably 50 mol% or less, based on 100 mol% of all constituent components (all units) of the urethane-modified polyimide-based resin (A). It is 40 mol% or less, More preferably, it is 30 mol% or less. The urethane unit (iv) contributes to improving the solubility in solvents and the flexibility of the film, but when it is too large, the progress of the polymerization is delayed, and the heat resistance, chemical resistance, and mechanical properties of the obtained urethane-modified polyimide-based resin may be lowered.

<Other ingredients>

Further, in the urethane-modified polyimide-based resin used in the present invention, aliphatic, alicyclic, or aromatic polycarboxylic acids may be further copolymerized as necessary within a range not impairing the target performance. Examples of aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, dodecanedioic acid, eicosandioic acid, 2-methylsuccinic acid, 2-methyladipic acid , 3-methyladipic acid, 3-methylpentanedicarboxylic acid, 2-methyloctanedicarboxylic acid, 3,8-dimethyldecanedicarboxylic acid, 3,7-dimethyldecanedicarboxylic acid, 9, 12-dimethyleicosanoic acid, fumaric acid, maleic acid, dimer acid, hydrogenated dimer acid, and the like. Examples of the alicyclic dicarboxylic acid include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 4,4'-dicyclohexyl. Dicarboxylic acid etc. are mentioned. Examples of aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, oxydianbenzoic acid, and stilbendicarboxylic acid. These dicarboxylic acids may be used alone or in combination of two or more. Considering heat resistance, adhesion, solubility, cost, etc., 1,4-cyclohexanedicarboxylic acid and isophthalic acid are preferred.

In addition, in the present invention, in addition to polyoxyalkylene glycols, other flexible components may be further copolymerized as needed within a range not impairing the target performance. For example, aliphatic/aromatic polyester diols (manufactured by Toyobo Co., Ltd., trade name VYLON (registered trademark) 220), aliphatic/aromatic polycarbonate diols (manufactured by Daisel Kagaku Kogyo Co., Ltd., trade name PLACCEL (registered trademark)- CD220, manufactured by Kuraray Co., Ltd., trade name C-2015N, etc.), polycaprolactonediols (manufactured by Daicel Kagaku Kogyo Co., Ltd., trade name PLACCEL (registered trademark)-220, etc.), carboxy-modified acrylonitrile butadiene rubber ( Ube Kosan Co., Ltd. product name HyproCTBN1300x13, etc.), polydimethylsiloxane diol, polymethylphenylsiloxane diol, and polysiloxane derivatives such as carboxy-modified polydimethylsiloxanes.

The urethane-modified polyimide-based resin is preferably composed of only four units of amide-imide unit (i), urethane unit (ii), imide unit (iii) or urethane unit (iv).

One of the characteristics of the urethane-modified polyimide-based resin of the present invention is that it has excellent heat resistance and chemical resistance, and at the same time forms a flexible film with excellent bendability. As a standard, it is preferable that the modulus of elasticity is 2500 MPa or less. When the elastic modulus exceeds 2500 MPa, the resin becomes brittle, and when applied to, for example, a paint for the inner surface of a metal can, the coating film may crack during bending or drawing in the can manufacturing process.

The logarithmic viscosity of the urethane-modified polyimide-based resin used in the present invention is preferably 0.1 dl/g or more and 2.0 dl/g or less, more preferably 0.2 dl/g or more and 1.5 dl/g or less. When the logarithmic viscosity is less than 0.1 dl/g, the heat resistance may decrease or the coating film may become brittle.

The glass transition temperature of the urethane-modified polyimide-based resin used in the present invention is preferably 80°C or higher, more preferably 100°C or higher.

<Organic solvent (B)>

The organic solvent used in the present invention is at least one selected from the group consisting of cyclohexanone and cyclopentanone. By not using commonly used polar solvents with high boiling point and high hygroscopicity such as NMP, DMAc, or GBL at all, drying, workability, and productivity are excellent, and polyimide-based resins have inherent heat resistance and mechanical properties, It is possible to obtain a resin that is flexible and has excellent flexibility while maintaining chemical resistance.

<Urethane-modified polyimide-based resin solution>

The urethane-modified polyimide-based resin solution of the present invention is a resin solution obtained by dissolving the urethane-modified polyimide-based resin (A) in an organic solvent (B).

The urethane-modified polyimide-based resin of the present invention does not need to be mixed with a polar solvent having a high boiling point and high hygroscopicity such as NMP, DMAc, or GBL in order to dissolve in a non-amide-based solvent such as cyclohexanone and/or cyclopentanone. does not exist. As a result, a urethane-modified polyimide-based resin solution having excellent drying properties, workability, and productivity, and being flexible and excellent in flexibility while maintaining the inherent heat resistance, mechanical properties, and chemical resistance of the polyimide-based resin can be obtained.

When the urethane-modified polyimide-based resin solution of the present invention is applied to a paint for the inner surface of a metal can or an ink for screen printing, a single solution of the urethane-modified polyimide-based resin may be used, but the heat resistance of the urethane-modified polyimide-based resin of the present invention However, a curing agent may be incorporated to further improve mechanical properties, flexibility during bending, and chemical resistance.

As the curing agent, polyfunctional epoxy compounds, amino resins, and isocyanate compounds are preferably used.

Examples of the polyfunctional epoxy compound include, but are not particularly limited to, bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol novolak type epoxy resins, amine type epoxy resins, alicyclic epoxy resins, and brominated epoxy resins. and the like, preferably JER (registered trademark) 828, JER 1001, and JER 1004 of Mitsubishi Chemical Corporation as the bisphenol A type, JER 152 of Mitsubishi Chemical Corporation as the phenol novolak type, JER 154 and Dainippon Ink Co., Ltd.'s N-730A, N-740, N-770, N-775, etc. are used.

As the amino resin, polyfunctional melamine compounds are preferable, and specifically, melamine resins such as trimethylolmelamine, hexamethylolmelamine, and alkoxyether compounds thereof, benzos such as methylated benzoguanamine resins and butylated benzoguanamine resins. and guanamine resin.

In addition, as the polyfunctional isocyanate compound, as the bifunctional diisocyanate compound and trifunctional isocyanate compound used in the synthesis of the urethane-modified polyimide-based resin of the present invention, 2,4-tolylene diisocyanate adduct of trimethylolpropane or hexamethylene and cyclic trimers such as diisocyanate, diphenylmethane-4,4'-diisocyanate, and isophorone diisocyanate, and block bodies obtained by protecting these with phenol or alcohol.

The compounding amount of these curing agents depends on the purpose, but is used in the range of 1 to 50 parts by weight, preferably 3 to 30 parts by weight, based on 100 parts by weight of the solid content of the urethane-modified polyimide-based resin. If the blending amount of the curing agent is less than 1 part by weight, there is little effect on improving heat resistance or chemical resistance, and if it exceeds 50 parts by weight, the coating film becomes brittle, and there is a risk that the coating film is cracked during bending.

In the urethane-modified polyimide-based resin solution of the present invention, in addition to the curing agent, other resins as necessary, for example, polyamide-imide resins other than the urethane-modified polyimide-based resins of the present invention, polyimide resins, polyamide resins, polyester resins, Acrylic resins, polyurethane resins, polyethersulfone resins, polyetherimide resins and the like can be blended within a range not impairing the object of the present invention.

In addition, a colorant, an antistatic agent, and a flame retardant may be blended with the urethane-modified polyimide-based resin solution of the present invention, if necessary.

As an application of the urethane-modified polyimide-based resin of the present invention, ink for screen printing is promising. In particular, acrylic resins, epoxy resins, polyester resins, and combinations thereof have conventionally been used for insulating coating agents and interlayer adhesives for printed circuit boards, but they have problems in heat resistance and chemical resistance. On the other hand, polyimide-based resins are excellent in heat resistance and chemical resistance as described above, but since solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide with high hygroscopic properties are used, There was a drawback that the resin precipitated and solidified during printing, causing clogging of the screen board.

Since cyclohexanone or cyclopentanone used in the urethane-modified polyimide-based resin of the present invention has low hygroscopicity and appropriate volatility, it is possible to suppress clogging of screen plates and provide ink with excellent continuous printing properties.

For that purpose, it is preferable to impart thixotropic properties (thixotropy) by blending organic or inorganic fine particles into the urethane-modified polyimide-based resin solution of the present invention to improve plate separation during printing.

The fine particles used may be those commonly used and are not particularly limited. Specifically, examples of the inorganic fine particles include silica, alumina, titania, zirconia, silicon nitride, barium titanate, barium sulfate, barium carbonate, carbon, and the like.

Examples of organic particulates include epoxy resin particulates, polyimide resin particulates, and benzoguanamine resin particulates. These inorganic particulates and organic particulates may be used alone or in combination of two or more.

Further, in the case of application to ink for screen printing, a leveling agent or the like for preventing the occurrence of pinholes can be appropriately blended as needed.

In this way, the urethane-modified polyimide-based resin of the present invention was synthesized and dissolved in a low-boiling solvent such as cyclohexanone or cyclopentanone, which could not be achieved in the prior art by having a specific configuration, and completed a urethane-modified polyimide-based resin. As a result, a novel urethane-modified polyimide-based resin with excellent drying properties, workability, and productivity, and flexibility and excellent flexibility while maintaining the heat resistance, mechanical properties, and chemical resistance inherent in polyamideimide resin, and the inner surface of a metal can using the same It has become possible to provide useful screen printing inks for paints and circuit boards.

Example

Hereinafter, examples are shown to explain the present invention more specifically, but the present invention is not limited in any way by these examples. Unless otherwise specified, in the examples, simply "part" indicates weight part, and "%" indicates weight%.

In addition, the measured value described in the Example is measured by the following method.

<logarithmic viscosity>

A urethane-modified polyimide-based resin was dissolved in N-methyl-2-pyrrolidone to a polymer concentration of 0.5 g/dL, and the solution viscosity was measured at 30°C with an Uberode viscometer. The logarithmic viscosity was defined with the following formula.

(logarithmic viscosity)=(lnηrel)/C

ln: natural logarithm

ηrel: viscosity ratio of the solution to the pure solvent by measuring the solvent fall time (-)

C: concentration of solution (g/dl)

<Preparation of paint>

(combination)

Urethane-modified polyimide-based resin solution (30% by weight): 100 parts

B890 (blocked isocyanate manufactured by Mitsui Chemicals): 10 parts

BYK (registered trademark) 358 (Big Chemistry leveling agent): 1 copy

Aerosil (registered trademark) #300 (hydrophilic silica particles manufactured by Japan Aerosil Co., Ltd.): 3 parts

Floren AC326F (foaming agent manufactured by Kyoeisha Chemical Co., Ltd.): 1.5 parts

(kneading)

After stirring and mixing the solution with a disper, it was kneaded twice with a 3-roll mill. Cyclohexanone was added to this solution so that the solution viscosity under 25 degreeC might be 200 dPa.s, and the target paint was obtained.

Evaluation as a paint was conducted according to the following. The results are shown in Table 2.

<Adhesion>

The coating material was applied to a 0.3 mm thick aluminum plate manufactured by Daiyukizai Co., Ltd. to a dry film thickness of about 5 μm, and dried at 200° C. for 30 minutes to obtain a coated sample. Thereafter, 100 lattice patterns of 1 mm were made on the coating film surface of the paint according to JIS-K5600-5-6:1999, and a peeling test was conducted using cellophane tape to observe the peeling state of the lattice pattern.

(Judgment)

○: No peeling at 100/100

△: 70 to 99/100

×: 0 to 69/100

<Bendability>

When the coating sample was bent with the coated surface facing outward, the aluminum plate used for coating was sandwiched between the bent portions, and the number of sheets sandwiched when cracks occurred at the bent portions was evaluated.

(Judgment)

○: 0 sheets

△: 1 to 2 sheets

×: 3 or more

<Acid Resistance>

The sample, in which the uncoated surface of the coated sample was protected with cellophane tape, was immersed in a 5% sulfuric acid solution, and the state of the coated film after being allowed to stand at room temperature for 1 week was visually observed.

(Judgment)

○: no change

△: Blisters are seen

×: coating peeling off

<Alkali resistance>

The sample used for evaluation of acid resistance was immersed in 5% sodium hydroxide solution, and the state of the coating film after leaving it still at room temperature for 1 week was visually observed.

(Judgment)

○: no change

△: Blisters are seen

×: coating peeling off

<Preparation of ink>

(combination)

Urethane-modified polyimide-based resin solution (30% by weight): 100 parts

TETRAD (registered trademark) -X (epoxy compound manufactured by Mitsubishi Chemical Corporation): 4 parts

BYK 358 (Big Chemisa leveling agent): 1 copy

Aerosil #300 (hydrophilic silica particles manufactured by Nihon Aerosil Co., Ltd.): 3 parts

Floren AC326F (foaming agent manufactured by Kyoeisha Chemical Co., Ltd.): 1.5 parts

(kneading)

After stirring and mixing the ink with a disper, it was kneaded twice with a 3-roll mill. Cyclohexanone was added to this solution so that the solution viscosity under 25 degreeC might be 200 dPa.s, and the target ink was obtained.

Evaluation as an ink was conducted according to the following. The results are shown in Table 3.

<Thixotropy (tic ratio)>

Using a Brookfield BH rotational viscometer, the measurement was performed in the following procedure. The coating liquid obtained by preparing the coating liquid was put into a wide-sphere light-shielding bottle (100 ml), and the liquid temperature was adjusted to 25°C ± 0.5°C using a constant temperature water bath. Next, after stirring 40 times over 12 to 15 seconds using a glass rod, a predetermined rotor was installed, and after standing still for 5 minutes, the scale when rotated at 20 rpm for 3 minutes was read. The viscosity was calculated by multiplying this scale by the coefficient of the conversion table. Similarly, it was calculated by the following formula from the value of the viscosity measured at 25°C and 2 rpm.

Thixotropy = Viscosity (2 rpm) / Viscosity (20 rpm)

<Adhesion>

The coating solution obtained by preparing the above ink was applied to the copper foil surface of SPANEX M manufactured by Nippon Steel Chemical Co., Ltd. by screen printing, respectively, so that the dry film thickness was 15 μm, dried at 150 ° C. for 30 minutes, and heat treated. This was done to obtain a print sample. In accordance with JIS-K5600-5-6:1999, 100 1 mm lattice patterns were made on the ink coating surface, and a peeling test was conducted using cellophane tape to observe the lattice-like peeling state. The same was done for the case where a polyimide film having a thickness of 25 µm was used as the base material.

(Judgment)

○: No peeling at 100/100

△: 70 to 99/100

×: 0 to 69/100

<flexibility>

The ink obtained by preparing the above ink was thin-printed on the copper foil surface of SPANEX M manufactured by Shin-Nitte Tsukagaku Co., Ltd. by screen printing so that the dry film thickness was 15 μm, and then dried at 150 ° C. for 3 hours. The processing was performed to obtain a print sample. The flexibility evaluation of this print sample was evaluated according to JIS-K5400:1990. The diameter of the mandrel was set to 2 mm, and the presence or absence of cracks was confirmed.

(Judgment)

○: no cracks

×: with cracks

<Continuous printability>

When 500 sheets of continuous screen printing were performed by the method described below using the ink obtained by preparing the above ink, resin precipitation from the ink and clogging of the screen plate due to an increase in viscosity were observed.

[Print Conditions]

SUS screen plate (Murakami Co., Ltd. 150 mesh, oil agent 30 μm) was used so that the dry film thickness was 15 μm on the copper foil surface of SPANEX M manufactured by Nippon Steel Co., Ltd., and the line width was 1 cm. , 500 sheets of patterns were continuously printed with a line length of 5 cm and an interval of 3 cm between lines.

(Judgment)

○: The clogging of the screen plate is suppressed, and the continuous printability is excellent.

x: Clogging of the screen plate is not suppressed, and continuous printability is poor.

[Synthesis Example 1] PAI-A (TMA/TMEG/TCD-DM//MDI=35/35/30//100)

0.35 mol of trimellitic anhydride (TMA), 0.35 mol of ethylene glycol bisanhydrotrimellitate (TMEG TMEG 200 manufactured by New Japan Chemical), Tricyclodecane dimethanol (TCD-DM): 0.3 mol, diphenylmethane-4,4'-diisocyanate (MDI): 1 mol and 1,8-diazabicyclo[5,4,0]-7 as catalyst -Undecene (DBU): 0.01 mol was injected together with cyclohexanone so that the solid content concentration was 50%, and the reaction was heated to 80 ° C. for about 1 hour while stirring, and after the exotherm subsided, the temperature was raised to 120 ° C. for 5 more hours. reacted Subsequently, while cooling, it was diluted with cyclohexanone so that the solid content concentration would be 30%, and a urethane-modified polyimide-based resin solution (PAI-A) was synthesized.

[Synthesis Example 2] PAI-B solvent CPN change

Using the same equipment as in Synthesis Example 1, a urethane-modified polyimide-based resin solution (PAI-B) was synthesized under the same conditions as in Synthesis Example 1, except that cyclohexanone used in Synthesis Example 1 was replaced with cyclopentanone.

[Synthesis Example 3] PAI-C (TMA/TMEG/TCD-DM/PTMG850//MDI=35/30/30/5//100)

Using the same apparatus as in Synthesis Example 1, the raw materials were injected: TMA: 0.35 mol, TMEG: 0.3 mol, TCD-DM: 0.3 mol, polytetramethylene glycol (Sunnix (registered trademark) PTMG #850 manufactured by Sanyo Kasei Kogyo Co., Ltd.) molecular weight 850): 0.05 mol, diphenylmethane-4,4'-diisocyanate (MDI): 1 mol, DBU: 0.01 mol were injected together with cyclohexanone so that the solid content concentration was 50%, and the same conditions as Synthesis Example 1 A urethane-modified polyimide-based resin solution (PAI-C) was synthesized.

[Synthesis Example 4] PAI-D (TMA/TMEG/TCD-DM/PPG1000///MDI=35/35/25/5//100)

Using the same apparatus as Synthesis Example 1, as raw materials, TMA: 0.35 mol, TMEG: 0.35 mol, TCD-DM: 0.25 mol, polypropylene glycol (Sanyo Kasei Kogyo Co., Ltd. Sunix (registered trademark) PPG# 1000 molecular weight 1000) : 0.05 mol, MDI: 1 mol, DBU: 0.01 mol were injected together with cyclohexanone so that the solid content concentration was 50%, and a urethane-modified polyimide-based resin solution (PAI-D) was synthesized under the same conditions as in Synthesis Example 1. .

[Synthesis Example 5] PAI-E two-stage polymerization (TMA/TMEG/TCD-DM//MDI=30/30/40//100)

Using the same apparatus as in Synthesis Example 1, 0.4 mol of TCD-DM and 0.8 mol of MDI were injected together with cyclohexanone so that the solid content concentration was 50%, the temperature was raised to 80°C, reacted for 1 hour, and then heated to 60°C or less. After cooling, 0.3 mol of TMA, 0.3 mol of TMEG, 0.2 mol of MDI, and 0.01 mol of DBU were injected together with cyclohexanone so that the solid concentration was 50%. This solution was heated again to 80 ° C. and reacted for about 1 hour, heated to 120 ° C. and reacted for 5 hours, and then diluted with cyclohexanone so that the solid content concentration was 30% while cooling, and a urethane-modified polyimide-based resin solution (PAI -E) was synthesized.

[Synthesis Example 6] PAI-F (TMA//MDI=100//100)

Using the same apparatus as in Synthesis Example 1, 1 mol of TMA and 1 mol of MDI were injected together with a mixed solvent of cyclohexanone/NMP = 4/1 so that the solid content concentration was 30%, and the same conditions as in Synthesis Example 1 was synthesized to prepare a urethane-modified polyimide-based resin solution (PAI-F). However, as the polymerization progressed, the solution became opaque and the molecular weight did not rise sufficiently.

[Synthesis Example 7] PAI-G (TMA/TMEG/TCD-DM//MDI=5/5/90//100)

Using the same apparatus as in Synthesis Example 1, 0.05 mol of TMA, 0.05 mol of TMEG, 0.9 mol of TCD-DM, 1 mol of MDI, and 0.01 mol of DBU were added as raw materials together with cyclohexanone so that the solid concentration was 50%. and a urethane-modified polyimide-based resin solution (PAI-G) having a urethane group concentration outside the scope of the claims was synthesized under the same conditions as in Synthesis Example 1.

[Synthesis Example 8] PAI-H (TMA/TCD-DM//MDI=60/40//100)

0.6 mol of trimellitic anhydride (TMA), 0.4 mol of tricyclodecanedimethanol (TCD-DM), diphenylmethane-4, 4'-diisocyanate (MDI): 1 mole and 1,8-diazabicyclo[5,4,0]-7-undecene (DBU): 0.01 mole as a catalyst were mixed with cyclohexanone to a solid content concentration of 50%. Injected together, heated to 80 ° C. while stirring and reacted for about 1 hour, and after the exotherm subsided, heated to 120 ° C. and reacted for another 5 hours. Then, while cooling, it diluted with cyclohexanone so that the solid content concentration might be 30%, and the urethane-modified polyimide-type resin solution (PAI-H) was synthesize|combined.

[Synthesis Example 9] PAI-I (TMA/TMEG/TCD-DM//MDI=35/5/60//100)

0.35 mol of trimellitic acid anhydride (TMA), 0.05 mol of ethylene glycol bisanhydrotrimellitate (TMEG TMEG 200 manufactured by New Japan Chemical), Tricyclodecane dimethanol (TCD-DM): 0.6 mol, diphenylmethane-4,4'-diisocyanate (MDI): 1 mol and 1,8-diazabicyclo[5,4,0]-7 as catalyst -Undecene (DBU): 0.01 mol was injected together with cyclohexanone so that the solid content concentration was 50%, the reaction was heated to 80 ° C. for about 1 hour while stirring, and after the exotherm subsided, the temperature was raised to 120 ° C. for 5 more hours. reacted Subsequently, while cooling, it was diluted with cyclohexanone so that the solid content concentration would be 30%, and a urethane-modified polyimide-based resin solution (PAI-I) was synthesized.

Table 1 shows the contents of the urethane-modified polyimide-based resin solutions (PAI-A to PAI-I) of Synthesis Examples 1 to 9. Using PAI-A to PAI-I, paints 1 to 6 (Examples 1 to 6), comparative paints 1 to 2 (Comparative Examples 1 to 2), inks 1 to 2 (Examples 7 to 8) and comparative inks 1 and 2 (Comparative Examples 3 and 4) were prepared and evaluated as paints and inks. The results are shown in Tables 2 and 3.

Since the urethane-modified polyimide-based resin solution of the present invention dissolves in cyclohexanone and/or cyclopentanone as an organic solvent, there is no need to use a polar solvent with a high boiling point and high hygroscopicity such as NMP, DMAc or GBL. . Therefore, it is possible to provide a urethane-modified polyimide-based resin solution that is excellent in low-temperature drying properties, workability, and productivity, and is flexible and excellent in flexibility while maintaining the inherent heat resistance, mechanical properties, and chemical resistance of polyimide-based resins. .

Claims (11)

When the total components of the urethane-modified polyimide-based resin (A) are 100 mol%, 30 to 90 mol% of the amideimide unit (i) composed of a trimellitic acid derivative and an aromatic diisocyanate component, the general formula (1 ) and a urethane-modified polyimide-based resin (A) containing 10 to 70 mol% of a urethane unit (ii) composed of an aromatic diisocyanate component, cyclohexanone and cyclopentanone selected from the group consisting of A urethane-modified polyimide-based resin solution containing the above organic solvent (B).

(In general formula (1), m and n are integers greater than or equal to 1, and may be the same or different.) The urethane-modified polyimide-based resin solution according to claim 1, wherein the urethane-modified polyimide-based resin (A) further contains an imide unit (iii) composed of a tetravalent polycarboxylic acid derivative and an aromatic diisocyanate component. The urethane-modified polyimide-based resin solution according to claim 2, wherein the tetravalent polycarboxylic acid derivative is alkylene glycol bisanhydrotrimellitate. The urethane-modified polyimide-based resin solution according to claim 2, wherein the tetravalent polycarboxylic acid derivative is ethylene glycol bisanhydrotrimellitate. The urethane-modified polyimide according to any one of claims 1 to 4, wherein the urethane-modified polyimide-based resin (A) further contains a urethane unit (iv) composed of a polyalkylene glycol component and an aromatic diisocyanate component. based resin solution. The urethane-modified polyimide-based resin solution according to claim 5, wherein the polyalkylene glycol component is at least one of polytetramethylene glycol and polypropylene glycol. At least one compound selected from the group consisting of a polyfunctional epoxy compound, an amino resin, a polyfunctional isocyanate compound, and a polyfunctional phenol resin is added to the urethane-modified polyimide-based resin solution according to any one of claims 1 to 4 A composition for painting the inner surface of a metal can. A paint for the inner surface of a metal can, characterized in that the composition for a paint for the inner surface of a metal can according to claim 7 is blended with at least one of inorganic fine particles and organic fine particles. At least one compound selected from the group consisting of a polyfunctional epoxy compound, an amino resin, a polyfunctional isocyanate compound, and a polyfunctional phenol resin is added to the urethane-modified polyimide-based resin solution according to any one of claims 1 to 4 A composition for screen printing ink containing An ink for screen printing characterized in that the composition for screen printing ink according to claim 9 is blended with at least one of inorganic fine particles and organic fine particles. A trimellitic acid derivative and an aromatic compound obtained by polymerizing a trimellitic acid derivative, a compound represented by formula (1), and an aromatic diisocyanate in at least one organic solvent (B) selected from the group consisting of cyclohexanone and cyclopentanone A urethane-modified polyi containing 30 to 90 mol% of an amideimide unit (i) composed of diisocyanate and 10 to 70 mol% of a urethane unit (ii) composed of a compound represented by the general formula (1) and an aromatic diisocyanate Method for producing mead-based resin (A).

(In general formula (1), m and n are integers greater than or equal to 1, and may be the same or different.)