Method for obtaining an insulating coating composition, coating composition, and conductive material containing the same

Abstract

The present invention relates to a method for obtaining an insulating coating material, a coating composition, and a conductive material containing the same. In particular, the present invention discloses a method for obtaining a coating material containing a polyester and a polyesterimide without using cresol or its derivatives as a solvent. The formation of the polyesterimide is carried out in two steps: the formation of the polyester followed by the formation of the imide moiety. The coating composition obtained by this method and the conductive material containing the composition are also claimed.

Description

Detailed Description of the Invention

[0001] FIELD OF THE INVENTION The present invention relates to a method for obtaining an insulating coating material, a coating composition, and a conductive material containing the same. In particular, the present invention discloses a method for obtaining a coating material containing a polyester and a polyesterimide without using cresol or its derivatives as a solvent. The formation of the polyesterimide is carried out in two steps: the formation of the polyester followed by the formation of the imide moiety. The coating composition obtained by this method and the conductive material containing the composition are also claimed.

[0002] These process conditions resulted in compositions containing the unique properties of high solids content and low polydispersity in addition to providing a substantially uniform surface coating.

[0003] BACKGROUND OF THE INVENTION Typically, enameled wire consists of a solid conductor, typically made of copper or aluminum, covered with an electrically insulating film formed by a thermosetting polymer material. Adjacent wires may be subjected to high voltages and / or pulse loads. Therefore, it is desirable for such a film or coating to have high resistance to partial discharges. In this context, resins based on polymer materials are widely known for forming insulating coatings.

[0004] The resins used in the manufacture of enameled wire are dissolved in a specific solvent (the system is called an enamel). These consist of approximately 20-50% solids and 50-80% solvents and diluents. Commonly used solvents and diluents are cresol compounds (phenol, cresol, xylenol, and alkylphenols), xylene derivatives, alkylbenzenes, and alcohols, respectively. The presence of diluents facilitates solvent evaporation, reduces the viscosity of the enamel, and consequently improves the quality of the coating.

[0005] Common polymeric materials include polyester, polyurethane, polyimide, polyamideimide, epoxy, vinyl formaldehyde, and polyesterimide because they can withstand high temperatures during continuous processing.

[0006] Polyester is known for its low cost and ease of handling. Despite its widespread use, polyester has some stability issues. It can develop surface defects and, as a result, electrical leakage. This often requires a larger amount of resin to prevent scratches and cracks from forming during or after the curing process.

[0007] An alternative to overcome these limitations involves the use of special monomers and polyester-modifying groups for polymer formation, such as hydantoins. Another approach is to employ polyesterimide-based resins, which offer greater stability than polyester-based resins (BHANU, VA Polyester Wire Enamels - Reliable Coatings in the Wire Industry from the Beginning to Today. Macromolecular Materials and Engineering, volume 293, pages 340 to 249, 2008). However, the use of polyesterimides still faces limitations related to cost and high toxicity, making large-scale applications difficult to implement.

[0008] In particular, the solvent systems used in polyesterimide resin solutions increase packaging, shipping, and storage costs. Mixed solvents containing phenol and its derivatives (e.g., cresol, xylenol), and aromatic hydrocarbons are commonly used.

[0009] In some methodologies, cresol is used as a solvent to promote the formation of polyesters and polyesteroids. The ability of cresol to solubilize polymers is particularly desirable, and cresol can be incorporated into resins at the end or during the production process. Such methodologies are described, non-exhaustively, in patent documents U.S. Pat. Nos. 4,384,946, 6,211,326, 3,919,144, 3,859,284, and CA1103,841. However, cresol and its derivatives are highly toxic and therefore contrary to the principles of green chemistry.

[0010] Several efforts have been made to reduce the use of these solvents: reducing the amount of cresol-based solvents using excess amounts of polyols (EP 0009653), aqueous reaction systems (US 4116941), or cresol and derivative-free systems (DE 4133161 and US 7521498).

[0011] Meanwhile, US 4,117,032 discloses a process using excess polyol in the presence of cresylic acid to disperse the catalyst. This reference details a two-step reaction for forming polyesterimide resins. First, a polyester is formed by reacting a mixture of glycol and triol with an organic diacid, followed by the in situ addition of imide-forming reagents trimellitic anhydride and an aromatic diamine. To ensure stable solubility in aqueous solvent systems, the product is then reacted with additional trimellitic anhydride. In the second reaction, a more random polymer is created by simultaneously generating imide and polyester segments by reacting a mixture of glycol and triol, a mixture of organic diacid and trimellitic anhydride, and a diamine.

[0012] EP0009653 describes a process that includes mixing an excess of a polyol component, a polyfunctional carboxylic acid compound, a diethylene glycol monoalkyl ether acetate, and a catalyst. Preferably, a fatty acid is also included in the composition.

[0013] On the other hand, DE 4133161 reports a process for preparing cresol-free resins: the absence of any kind of phenolic solvent strongly influences the solubility of the polymer in the resin, thereby resulting in greater polymer heterogeneity (residue) and a reduced solids content of the final composition.

[0014] US 7,521,498 describes cresol-free enamels in which at least 50% by weight of the solvent / diluent consists of an aromatic monocyclic alkyl carboxylic acid ester, or 3,5,5-trimethyl-2-cyclohexen-1-one, or a mixture of methyl benzoate and 3,5,5-trimethyl-2-cyclohexen-1-one. This reference is said to overcome the drawbacks of the solids content identified in DE 4,133,161 (which describes obtaining compositions containing 20-60% by weight).

[0015] In this regard, it is worth emphasizing that none of the examples in US 7521498 result in compositions with a solids content of more than 40%. Furthermore, it can be observed that in all embodiments, a catalyst (e.g., zinc acetate) is required at various stages of the process.

[0016] Such catalysts affect the linearity of the polymer by increasing the polydispersity and, consequently, the homogeneity of the polymer, a behavior exacerbated by the lack of selectivity (the lack of directionality towards the production of specific groups of polyesterimide polymer).

[0017] As a result, the process described in US 7,521,498 results in enamels with a high degree of surface imperfections, which affect the insulating efficiency of the material and necessitate the addition of larger amounts of product to fill the surface scratches and cracks. Furthermore, the process of US 7,521,498 involves the generation of methanol, a substance that is considered highly toxic, as a by-product of the reaction. In contrast, in the present invention, only water is generated and / or released during the process.

[0018] It is clear that the process for obtaining the coatings has some limitations related to the low solids content of the resins obtained and the high heterogeneity of the residual monomers.

[0019] Therefore, there is a need for a more effective method that provides resins that are more uniform in content and have sufficient solids content without complex processes that are economically unfeasible for production on an industrial scale.

[0020] [Object of the Invention] The process described by this invention overcomes the drawbacks of the prior art by providing a method for obtaining coating materials containing polyesters and polyesterimides without using cresols and derivatives as solvents. The formation of polyesterimides is carried out in two steps: formation of the polyester followed by the formation of the imide moiety. Also claimed are coating compositions obtained by this method and conductive materials containing the compositions.

[0021] The formation of polyesters and polyesterimides in separate steps in solid media, in conjunction with the use of catalysts and directing solvents, has resulted in polymers with more uniform molar mass and lower polydispersity, leading to polyester- and polyesterimide-based resins with high coating uniformity.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a flow chart of the manufacturing process steps.

[0023] FIG. 2 shows the delta tangent analysis of a commercial polyesterimide containing cresol.

[0024] FIG. 3 shows the delta tangent analysis of the resin obtained according to the present invention.

[0025] Detailed Description of the Invention The present invention includes a method for obtaining an insulating coating composition, said method comprising the steps of: i) polyester formation reaction by in situ formation of isolated polyester in a solid medium, by adding at least one acid component monomer in a concentration range of 5% to 10%, at least one alcohol component monomer in a concentration range of 3% to 25%, and at least one catalyst in a concentration range of 0.01% to 1.0% to the reaction medium, and heating the reaction medium to 180 to 260°C until the acid value is less than 5 mg KOH / g; ii) a) forming imide moieties in situ in a solid medium by adding at least one acidic monomer in the range of 8% to 18% and at least one amine monomer in the range of 2% to 10% to the reaction medium and heating to 180°C to 260°C for 1 hour to 8 hours; b) cooling the medium to a temperature range of 120°C to 180°C and adding at least one acidic monomer in the range of 8% to 18% and at least one amine monomer in the range of 2% to 10% to the reaction medium until the medium reaches a kinematic viscosity in the range of 50 seconds to 80 seconds. polycondensation reactions, including; iii) dissolving the material resulting from step ii) using at least one organic solvent, preferably selected from phenol, glycol ether, dimethyl glycol, ethyl glycol, isopropyl glycol, butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, 3,5,5-trimethyl-2-cyclohexen-1-one, alkyl benzene, phenyl glycol, glycol ether ester, methyl glycol acetate, butyl glycol acetate, methoxypropyl acetate; iv) Additive treatment, preferably by incorporating at least one additive selected from hardening additives, chain extension additives, and antioxidant additives at a temperature below 100°C; v) Adjustment of viscosity by adding organic solvents, diluents, or combinations thereof at temperatures below 100°C.

[0026] The following terms are defined for the purposes of clarity. It should be understood that these terms should not be construed as limiting, but rather as a means to place the presented invention in context.

[0027] The term "wire enamel" should be understood as a composition containing polymer macromolecules dissolved in a suitable solvent, which, when applied to the surface of a material, forms a film or coating layer that provides electrical insulation, high thermal and mechanical stability, flexibility, and moisture resistance.

[0028] In the present invention, the term "acidic component" should be understood as an organic acid and / or acid anhydride, and should be interpreted as a compound having two acyl groups attached to the same oxygen atom according to the IUPAC definition. The acidic component according to the present invention may include terephthalic acid, tricarboxylic acid anhydrides (e.g., trimellitic anhydride (TMA), 3,4,4'-benzophenonetricarboxylic acid anhydride, or 3,4,4'-biphenyltricarboxylic acid anhydride).

[0029] Further components include tetracarboxylic dianhydrides in combination with tricarboxylic anhydrides. Among the tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides (e.g., pyromellitic dianhydride (PMDA), 3,3'4,4'-benzophenone-tetracarboxylic dianhydride (BTDA), boxylic dianhydride (DSDA), 4,4'-oxydiphalic dianhydride (ODPA), and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride) can be used. Additionally, alicyclic tetracarboxylic dianhydrides, such as butane tetracarboxylic dianhydride, or oralicyclic tetracarboxylic dianhydride, which is a hydrogenated aromatic tetracarboxylic dianhydride, can be used in combination with the carboxylic ester anhydride.

[0030] According to the present invention, the term "alcohol component" is to be interpreted as a polyhydric alcohol.

[0031] The alcohol component includes, but is not limited to, the following alcohols: dihydric alcohols (ethylene glycol (EG)), neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, or 1,6-cyclohexanedimethanol; (trihydric alcohols, such as glycerin, trimethylolpropane, or pentaerythritol), and alcohols having an isocyanurate ring (tris(hydroxymethyl)isocyanurate; tris(2-hydroxyethyl)isocyanurate (THEIC); tris(3-hydroxypropyl)isocyanurate, etc.).

[0032] The term "catalyst" should be interpreted according to its literary definition, i.e., as an element that increases the reaction rate without being consumed. Non-exhaustive examples of catalysts that can be used in the present invention include heavy metal salts, organic titanates, cerium compounds, and organic acids. Other possible catalysts include tin catalysts or other metal catalysts; amine catalysts (e.g., diazabicyclo-undecene catalysts, diazabicyclo-octane catalysts); or other amines known to those skilled in the art. These can be used alone or in mixtures.

[0033] Examples of heavy metal salts include lead acetate and zinc acetate. The coating composition obtained by the process of the present invention does not contain heavy metals because the raw materials used in the dissolution process do not contain heavy metals.

[0034] Examples of titanates that can be employed include tetramethyl titanate, tetraethyl titanate, tetraisopropyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetraamyl titanate, tetrahexyl titanate, diisopropyl titanate, dibutyl titanate, or amyl titanates such as tetraphenyl titanate, tetracresyl titanate, tetrahexyl titanate, triethanolamine titanate, etc. An example of an organic acid that can be preferentially used is p-toluenesulfonic acid.

[0035] The term "amine component" is to be understood as an amine that can be used in the process. In this regard, the use of aromatic diamines having three or more aromatic rings is preferred.

[0036] However, other amines can be used in the amidation process, such as primary aliphatic diamines (ethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, cycloaliphatic diamines (e.g., 4,4'-dicyclohexylmethanediamine), and triamines); secondary amines; aromatic amines (diaminodiphenylmethane, phenylenediamine, polynuclear aromatic amines, or toluenediamine); functionalized amines (amino alcohols, monoethanolamine, monopropanolamine), amino acids (e.g., glycine), aminocaproic acid, or aminobenzoic acid, and their esters; and amides of C-carboxy-3-oxocycloalkylcarboxylic acid groups, which can also be directly incorporated into the component.

[0037] Furthermore, to reduce the dielectric constant of the insulating material in dry and hygroscopic states while maintaining heat resistance, a diamine component containing an aromatic diamine having three or more aromatic rings can be used. Non-exhaustive examples of such aromatic diamines having three or more aromatic rings include the following: 2,2-bis(4-(4-aminophenoxy)phenylpropane (BAPP); bis4-(4-aminophenoxy)phenylsulfone (BAPS), bis4-(4-aminophenoxy)phenylether (BAPE), fluorenediamine (FDA), 4,4'-bis(4-aminophenoxy)bisphenyl (BAPB), and 1,4-bis(4-aminophenoxy)benzene, their isomers, and combinations of these amines.

[0038] Furthermore, as the diamine component, an aromatic diamine (e.g., 4,4'-diaminodiphenylmethane (DAM) or 4,4'-diaminodiphenyl ether (DDE)) can be used in combination with an aromatic diamine having three or more aromatic rings. However, this process should not be limited to these specific examples.

[0039] The term "organic solvent" refers to a group of compounds whose molecules are essentially formed by carbon and hydrogen and which have certain physicochemical properties. In the context of the present invention, the interest in these organic solvents is directed to their ability to dissolve the polymers obtained in the process, which are important components of the wire resins and enamels.

[0040] Compounds such as phenol, glycol ethers, dimethyl glycol, ethyl glycol, isopropyl glycol, butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, 3,5,5-trimethyl-2-cyclohexen-1-one, alkyl benzenes, phenyl glycol, esters of glycol ethers (e.g., methyl glycol acetate, butyl glycol acetate, methoxypropyl acetate), etc. are considered organic solvents according to the present invention.

[0041] Other examples of organic solvents are cyclic carbonates (eg, polypropylene carbonate), phenyl polyglycol ethers, cyclic esters (eg, γ-butyrolactone), dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0042] Additionally, aromatic solvents (eg, benzyl alcohol) can be used alone or in combination with the other solvents mentioned.

[0043] Furthermore, part of the organic solvent can be replaced by a cosolvent. It is preferred to use pure solvents or pure solvent mixtures, or solvents containing up to 40% by weight of cosolvent, based on the total weight.

[0044] These organic solvents can also be used with diluents. This approach is very common in processes for preparing enamels based on polyesters and polyesterimides. In this case, the solvent is suitable for promoting complete dissolution of the enamel, while the diluent is not used for this purpose.

[0045] According to the present invention, the term "thinner" should be understood as a substance suitable for diluting the already formed resin, such as an organic solvent or a mixture of organic solvents. These have the advantage of adjusting the viscosity of the resin solution and are usually added at the end of the process. The reason for their addition is to reduce production costs by replacing expensive special solvents and to ensure a uniform evaporation behavior during the hardening of the enamel.

[0046] Non-exhaustive examples of diluents are glycol ethers, isopropyl glycol, butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, 3,5,5-trimethyl-2-cyclohexen-1-one, alkyl benzenes.

[0047] In the context of the present invention, the term "additive" is used as any component that can modify the interactions between components to help induce the formation of more specific polymers of interest in the process. In the present case, the use of additives is very important to increase the stability and reduce the variation in molecular weight of the polymer, in addition to modifying and improving the rheology and line coating aspects.

[0048] The preferred additives that can be used in the present invention are curing additives, chain extension additives, and antioxidant additives. The preferred curing additive is tetrabutyl titanate. The prepolymer additive for providing chain extension is preferably made based on toluene diisocyanate. The preferred antioxidant additive is a phenolic resin.

[0049] In addition, other types of additives may be used, selected from antifoaming agents, dispersants, leveling agents, acidity regulators, stabilizers, and the like.

[0050] In the context of the present invention, the term "curing" should be interpreted as a chemical process that converts a prepolymer or polymer into a polymer with greater molar mass and connectivity, and ultimately into a network.

[0051] The term "polydispersity index" should be understood as a description of the distribution of molecular weights of a polymer. In this context, a high polydispersity necessarily means that the molecular weight distribution of the polymer is large. It is important to emphasize that in polymer synthesis processes, it is important that this index is not high; a high index strongly indicates the presence of significant heterogeneity between molecules. This suggests that the synthesis process is poorly directed and inefficient, resulting in the formation of non-specific molecules through undirected reactions.

[0052] The present invention relates to a process for producing polyester and polyesterimide based wire enamels, which does not use cresols at any stage of the process. The synthesis is carried out in two stages: complete formation of the polyester and formation of the imide moiety.

[0053] A brief description of the steps in this process includes: formation of the discrete polyester; formation of the imide moiety; final polymer dissolution; addition processing; and viscosity adjustment.

[0054] The polymer is produced through an in situ reaction in a solid medium without adding a solvent to the reaction medium. Furthermore, the polymer exhibits only water as a by-product of the reaction, with no residual organic solvent produced.

[0055] Another very important feature of this process is that the formation of polyesterimides occurs in two stages without the need for solvents. Dissolution and / or dilution only occur after the polymer conformation is complete. Therefore, the molecular weight depends only on the polymer obtained in the initial stage. As a result, at the end of the process, the evaporation of the solvent and diluent occurs linearly, thereby resulting in a defect-free cured coating and improved electrical properties.

[0056] In the context of the present invention, all amounts should be understood to be by weight unless otherwise specified. The initial reactants include an alcohol monomer, an acidic component, and a catalyst. These can be added to any suitable reaction medium (e.g., glass vessel, stainless steel, or any other metal used in the synthesis of polyesters, polyimides, and polyesterimides). Specific conditions for the above steps are detailed below in conjunction with Figure 1.

[0057] (i. Polyester Formation Reaction) The polyester is formed by adding to the reaction medium at least one acidic monomer in a concentration range of 5% to 10%, at least one alcoholic monomer in a concentration range of 3% to 25%, and at least one catalyst in a concentration range of 0.01% to 1.0%.

[0058] Once added to the reaction medium, heating is carried out in the temperature range of 180-260°C until the acid number is below 5 mg KOH / g. Carrying out this step separately and without the use of solvents is important to ensure sufficient directionality in the synthesis of the polyester chains. As a result, the polyester formed has greater homogeneity and linearity. This in turn leads to a reduction in polydispersity.

[0059] (ii. Polycondensation Reaction) After obtaining the polyester from step i, a new addition of materials is carried out in the same reaction medium, for the formation of imide moieties, the added materials being at least one acidic monomer in the range of 8% to 18% and at least one amine monomer in the range of 2% to 10%.

[0060] The reaction medium is then heated to a temperature of 160 to 220° C. for 1 to 8 hours.

[0061] The medium is then cooled and maintained at a temperature in the range of 120-180°C. Subsequently, the materials, namely at least one acidic monomer in a concentration range of 8%-18% and at least one amine monomer in a concentration range of 2%-10%, are added. The medium must be maintained under these conditions until it reaches a kinematic viscosity in the range of 50-80 seconds.

[0062] The content of imide groups should preferably be 0.02 to 0.8 mol.

[0063] The addition of materials at this stage of the process must be done in two phases and in the absence of solvent, and these conditions are important because, like step i, there is sufficient directionality for the synthesis of the polymer chain of interest.

[0064] As a result, the polyesterimide formed has greater material homogeneity and linearity, which in turn leads to a reduction in polydispersity, and, given that the polymer is formed in a solid medium, the content of homogeneous polymer is significantly higher.

[0065] The homogeneity of the polymer offers several advantages, one of the main being the high quality of the enamel after the curing process.

[0066] (iii.dissolution) The material resulting from step ii is solubilized using at least one of the solvents mentioned above, with the exception of cresol and its derivatives. It is important to emphasize that the dissolution is carried out after the polymerization process is complete and the polyesterimide is formed, i.e., after steps i and ii have been carried out in a solid medium.

[0067] The correct selection of the organic solvent or mixture of organic solvents is crucial at this stage, as it results in a very clear evaporation curve and a more harmonious evaporation process of the constantly changing azeotrope. As a result, the appearance of surface defects in the cured enamel film due to sudden changes is strongly suppressed.

[0068] (iv. Additive Treatment) In this process, at least one additive is incorporated at a temperature below 100°C.

[0069] These additives are introduced to block free hydroxyl and other reactive groups, thereby providing greater stability to the polyester and polyesterimide polymers formed by the time the enamel cures.

[0070] Finally, the viscosity is adjusted by adding at least one organic solvent, diluent, or combination thereof at a temperature below 100° C. to achieve a specific viscosity.

[0071] The present invention further includes an insulating coating composition obtainable by the described method, which comprises a polyester and a polyesterimide, wherein the ratio of polyester groups to imide groups ranges from 60:40 to 80:20, respectively.

[0072] Preferably, products of such compositions have a molecular weight (Mn) greater than 5000.

[0073] Preferably, products comprising such compositions have a polydispersity greater than 1.10.

[0074] Preferably, products comprising such compositions have a solids content of 34.0 to 40.0%.

[0075] Furthermore, the present invention further comprises a conductive material, preferably in cylindrical form, comprising a coating of the composition defined above, said conductive material having an enameled wire as its primary form of presentation.

[0076] The material resulting from this production process has the formulation set out in Table 1.

[0077] [Table 1]

[0078] Figures 2 and 3 show a comparison between commercially available polyesters and polyesters obtained from the process described above. The polyester and polyesterimide based enamels are suitable for application to wire, preferably using an enameling machine, resulting in enameled wire with superior electrical properties compared to those available in the art.

[0079] Example 1 The ingredients shown in Table 1 below were added to the reaction medium:

[0080] [Table 2]

[0081] The ingredients were then heated to 240°C and maintained until the acid number was less than 5 mg KOH / g.

[0082] After this step, the materials for the synthesis of the imide moiety shown in Table 2 were added to the medium containing the polyester.

[0083] [Table 3]

[0084] The medium was heated to a temperature of 200°C and maintained for 30 minutes. The medium was then cooled to 160°C, and a new addition of material was made using the same compounds and amounts as in the first phase of this stage to complete the process of imide moiety formation. These conditions were maintained until a kinematic viscosity of 60-65 seconds at 30°C was reached. This kinematic viscosity was measured by diluting a 10 gram aliquot of the product with 15 grams of n-methylpyrrolidone.

[0085] After the formation of the imide moiety was complete, the resulting polymeric material was dissolved in phenyl polyglycol ether.

[0086] At the end of the dissolution, the additives shown in Table 3 were added:

[0087] [Table 4]

[0088] After the loading step was completed, the resin was diluted with the solvents shown in Table 4.

[0089] [Table 5]

[0090] The resulting products were characterized based on the evaluation of the weight average molecular weight (Mw) and number average molecular weight (Mn), as well as the polydispersity index (Mw / Mn), the values ​​of which are shown in Table 5 below.

[0091] [Table 6]

[0092] (Measurement of dynamic viscoelasticity of resin) The results of dynamo-mechanical analysis (DMA) are shown in Figure 3. This test was performed according to ASTM D7028 and ASTM D4065 standards and provides the relationship between loss modulus and storage modulus (delta tangent). The maximum value of delta tangent characterizes the glass transition temperature (Tg).

[0093] The superiority of the polyester produced by this method can be confirmed by comparing the tests in Figures 2 and 3. The difference between the two samples is relatively low in terms of loss factor (delta tangent). However, it is noteworthy that it achieves thermal properties very similar to those of the cresol material.

[0094] Other results from tests with the resulting product were as follows: Kinematic viscosity: 60~63 seconds; Rotational viscosity: 600~700cPs; Solid content: 36-37%.

[0095] Example 2 The ingredients shown in Table 6 below were added to the reaction medium:

[0096] [Table 7]

[0097] These components were heated to 240°C and maintained until the acid value was less than 5 mg KOH / g. After this step, the materials for the synthesis of the imide moiety shown in Table 7 were added to the medium with the polyester.

[0098] [Table 8]

[0099] The medium was heated to 200°C and maintained for 30 minutes. The medium was then cooled to 160°C and a new addition of material was made using the same compounds and amounts as in the first phase of this stage to complete the process of imide moiety formation. Conditions were maintained until a kinematic viscosity of 60-65 seconds was reached.

[0100] After the formation of the imide moiety was complete, the resulting polymeric material was dissolved in phenyl polyglycol ether.

[0101] At the end of the dissolution, the additives shown in Table 8 were added:

[0102] [Table 9]

[0103] After the loading step was completed, the resin was diluted with the solvents shown in Table 9.

[0104] [Table 10]

[0105] The results obtained from tests with the resulting product were as follows: Kinematic viscosity: 60~63 seconds; Rotational viscosity: 600~700cPs; Solid content: 36~37%; Copper plate appearance: no craters and spots; Glass transition temperature: 176.4°C.

[0106] Example 3 The following ingredients shown in Table 10 were added to the reaction medium:

[0107] [Table 11]

[0108] These components were heated to 240°C and maintained until the acid value was less than 5 mg KOH / g. After this step, the materials for the synthesis of the imide moiety shown in Table 11 were added to the medium with the polyester.

[0109] [Table 12]

[0110] The medium was heated to 200°C and maintained for 30 minutes. The medium was then cooled to 160°C and a new addition of material was made using the same compounds and amounts as in the first phase of this stage to complete the process of imide moiety formation. These conditions were maintained until the kinematic viscosity at 30°C reached 60-65 seconds.

[0111] After the formation of the imide moiety was complete, the resulting polymeric material was dissolved in phenyl polyglycol ether.

[0112] At the end of dissolution, the additives shown in Table 12 were added:

[0113] [Table 13]

[0114] After the loading step was completed, the resin was diluted with the solvents shown in Table 13:

[0115] [Table 14]

[0116] The results obtained from tests with the resulting product were as follows: Kinematic viscosity: 60~63 seconds; Rotational viscosity: 600~700cPs; Solid content: 36~37%; Copper plate appearance: No craters or spots. [Brief explanation of the drawings]

[0117] [Figure 1] 1 shows a flowchart of the manufacturing process. [Figure 2] 1 shows the delta tangent analysis of commercial polyesterimides containing cresol. [Figure 3] 1 shows the delta tangent analysis of the resin obtained according to the present invention.

Claims

1. 1. A method for obtaining an insulating coating composition, characterized in that it comprises the steps of: i) polyester formation reaction by in situ formation of isolated polyester in a solid medium, by adding at least one acid component monomer in a concentration range of 5% to 10%, at least one alcohol component monomer in a concentration range of 3% to 25%, and at least one catalyst in a concentration range of 0.01% to 1.0% to the reaction medium, and heating at 180 to 260°C until the acid number is less than 5 mg KOH / g; ii) a) forming imide moieties in situ in a solid medium by adding at least one acidic component monomer in the range of 8% to 18% and at least one amine component monomer in the range of 2% to 10% to the reaction medium and heating to 180°C to 260°C for 1 hour to 8 hours; b) cooling the medium to a temperature range of 120°C to 180°C and adding to the reaction medium at least one monomer of the acid component in the range of 8% to 18% and at least one monomer of the amine component in the range of 2% to 10% until the medium reaches a kinematic viscosity in the range of 50 seconds to 80 seconds. a polycondensation reaction comprising: iii) dissolving the material resulting from step ii) using at least one organic solvent, preferably selected from phenol, glycol ether, dimethyl glycol, ethyl glycol, isopropyl glycol, butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, 3,5,5-trimethyl-2-cyclohexen-1-one, alkyl benzene, phenyl glycol, glycol ether ester, methyl glycol acetate, butyl glycol acetate, methoxypropyl acetate; iv) Addition treatment by incorporating at least one additive, preferably selected from hardening additives, chain extension additives, and antioxidant additives, at a temperature below 100°C; v) Adjusting viscosity by adding organic solvents, diluents, or combinations thereof at temperatures below 100°C.

2. 2. The method of claim 1, characterized in that the acidic component is preferably selected from terephthalic acid, a tricarboxylic acid anhydride, trimellitic anhydride (TMA), 3,4,4'-benzophenonetricarboxylic acid anhydride, or 3,4,4'-biphenyltricarboxylic acid anhydride, a tetracarboxylic acid dianhydride in combination with a tricarboxylic acid anhydride, or a combination thereof.

3. 3. The method of claim 2, wherein the tetracarboxylic dianhydride is selected from the group consisting of pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenone-tetracarboxylic dianhydride (BTDA), boxyl dianhydride (DSDA), 4,4'-oxydiphthalic dianhydride (ODPA), and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride.

4. 3. The method of claim 2, wherein the tetracarboxylic dianhydride, when combined with a carboxylic ester anhydride, can be selected from butane tetracarboxylic dianhydride or oralicyclic tetracarboxylic dianhydride.

5. 2. The method according to claim 1, wherein the alcohol component is preferably a polyhydric alcohol selected from dihydric alcohols (ethylene glycol, EG), neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, or 1,6-cyclohexanedimethanol; (trihydric alcohols, for example: glycerin; trimethylolpropane; or pentaerythritol), and alcohols having an isocyanurate ring (tris(hydroxymethyl)isocyanurate; tris(2-hydroxyethyl)isocyanurate (THEIC); tris(3-hydroxypropyl)isocyanurate).

6. 10. The method of claim 1, wherein the catalyst is selected from organic titanates, cerium compounds, and organic acids.

7. 7. The method according to claim 6, characterized in that the catalyst consisting of an organic titanate is selected from tetramethyl titanate, tetraethyl titanate, tetraisopropyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetraamyl titanate, tetrahexyl titanate, diisopropyl titanate, dibutyl titanate, or amyl titanates such as tetraphenyl titanate, tetracresyl titanate, tetrahexyl titanate, triethanolamine titanate.

8. 7. The method according to claim 6, characterized in that the catalyst consisting of an organic acid is preferably p-toluenesulfonic acid.

9. 2. The method of claim 1, wherein the amine component is selected from primary aliphatic diamines (ethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, cycloaliphatic diamines, 4,4'-dicyclohexylmethanediamine, and triamines); secondary amines; aromatic amines (diaminodiphenylmethane, phenylenediamine, polynuclear aromatic amines, or toluenediamine); functionalized amines (amino alcohols, monoethanolamine, monopropanolamine), amino acids (glycine), aminocaproic acid, or aminobenzoic acid, and esters thereof; and amides of C-carboxy-3-oxocycloalkylcarboxylic acid groups with aromatic diamines having three or more aromatic rings.

10. 2. The method of claim 1, wherein the amine component is an aromatic diamine having three or more aromatic rings, preferably selected from 2,2-bis(4-(4-aminophenoxy)phenylpropane (BAPP); bis-4-(4-aminophenoxy)phenyl sulfone (BAPS), bis-4-(4-aminophenoxy)phenyl ether (BAPE), fluorenediamine (FDA), 4,4′-bis(4-aminophenoxy)bisphenyl (BAPB), and 1,4-bis(4-aminophenoxy)benzene, isomers thereof, and combinations thereof.

11. Optionally, the amine component is 4,4'-diaminodiphenylmethane (DAM) or 4,4'-diaminodiphenylether (DDE) in combination with an aromatic diamine having three or more aromatic rings.

12. Optionally, the organic solvent is selected from the group consisting of polypropylene carbonate, phenyl polyglycol ether, cyclic esters (e.g., gamma-butyrolactone), dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

13. Optionally, the organic solvent is benzyl alcohol alone or in combination with phenol, glycol ether, dimethyl glycol, ethyl glycol, isopropyl glycol, butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, 3,5,5-trimethyl-2-cyclohexen-1-one, alkyl benzene, phenyl glycol, glycol ether ester, methyl glycol acetate, butyl glycol acetate, methoxypropyl acetate.

14. 10. The method of claim 1, wherein optionally, the organic solvent is replaced by up to 40% by a co-solvent.

15. 10. The method of claim 1, wherein the preferred hardening additive is tetrabutyl titanate.

16. 2. The method according to claim 1, characterized in that the preferred chain-extending additive is preferably made on the basis of toluene diisocyanate.

17. 2. The method of claim 1, wherein the preferred hardening additive is a phenolic resin.

18. 10. The method of claim 1, wherein optionally, the other additives may be selected from antifoaming agents, dispersants, leveling agents, acidity regulators, and stabilizers.

19. 2. The method according to claim 1, characterized in that the diluent is preferably selected from glycol ethers, isopropyl glycol, butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, 3,5,5-trimethyl-2-cyclohexen-1-one, alkyl benzenes.

20. 20. An insulating coating composition obtainable by the method according to any one of claims 1 to 19, characterized in that it comprises polyester and polyesterimide, and the ratio of polyester groups to imide groups is in the range of 60:40 to 80:20, respectively.

21. 21. The composition according to claim 20, characterized in that it is preferably obtained from a formulation of 2-30% by weight of acid, 5-50% by weight of alcohol, 3-35% by weight of amine, 0.01-2.5% by weight of catalyst, 15-75% by weight of solvent, and 1-10% by weight of additive.

22. 21. A composition according to claim 20, characterized in that the product of said composition preferably has a multi-molar mass (Mn) greater than 5000.

23. 21. A composition according to claim 20, characterized in that the product of said composition has a polydispersity greater than 1.

10.

24. A composition according to claim 20, characterized in that the product comprising such composition preferably has a solids content of 34.0 to 40.0%.

25. A conductive material, preferably in cylindrical form, characterized in that it comprises a coating composition according to claim 20.

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