Method of manufacturing water-soluble paint or coating agent

Abstract

To solve the problems of aqueous Quatlon (registered trademark), including storage problems (quality degradation over long periods of time, at high temperatures, under oxidizing conditions, etc.), transportation problems (need for special containers, transportation difficulties due to weight, need to prevent liquid leakage, etc.), hazards associated with the water dispersion, which complicate customs procedures when importing and exporting.SOLUTION: While mixing the aqueous polyamic acid dispersion with the alkali solution, under reduced pressure, the mixture is heated to evaporate the water content and processed to a solid state to achieve an instant (ready-to-use) polyimide dispersion formulation.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a painting or coating method using an aqueous paint or coating agent containing three components: an aqueous polyamic acid (PIA) solution, a PTFE dispersion (aqueous), and a polar crystal powder. More specifically, the present invention relates to a painting or coating method using a raw material composition in a solid state, for example, in the form of a powder or granule, as a raw material composition for the aqueous paint or coating agent. The raw material composition of the present invention can be suitably used as a solid preparation for preparing the water-soluble paint or coating agent when used. [Background technology]

[0002] Polyimide resin is known as a functional material with excellent heat resistance, cold resistance, etc. Among them, a mixture of polyimide and fluororesin containing PTFE (polytetrafluoroethylene) is known as a product using polyimide resin. This resin mixture has a low friction coefficient and excellent properties such as non-stickiness, chemical resistance, and heat resistance, so it is widely used for surface treatment of food industry products, kitchen utensils such as frying pans and pots, household products such as irons, electrical industry products, mechanical industry products, etc.

[0003] For example, Patent Document 1 discloses a polyimide precursor liquid composition in which the dispersion state of a fluororesin is uniformly controlled, a polyimide obtained from the composition and having excellent heat resistance, mechanical properties, electrical properties such as low dielectric constant and low dielectric loss tangent, and processability, a polyimide film, a method for producing the polyimide film, and a circuit board and a coverlay film using the polyimide film. However, the composition of Patent Document 1 uses an organic solvent as a solvent to uniformly disperse the polyimide and the fluororesin, and therefore has problems with handleability (safety, environmental load, equipment costs, etc.).

[0004] Thereafter, the present inventors attempted to develop an aqueous polyimide-fluororesin mixed dispersion having excellent adhesive properties and heat resistance without using an organic solvent, and attempted to develop an aqueous polyimide-fluororesin mixed dispersion having excellent adhesive properties and heat resistance without using an organic solvent. As a result, the present inventors completed an aqueous mixed dispersion containing polyimide, fluororesin, alumina, and potassium persulfate as such a dispersion, in which polyimide and fluororesin are uniformly dispersed, and a mixed powder produced from this dispersion, as well as a method for producing the same (Patent Document 2). This dispersion has excellent adhesive properties and heat resistance, and has excellent coating properties, and furthermore, since this polyimide-fluororesin mixed aqueous dispersion does not contain an organic solvent, it has excellent handleability (safety, environmental load, equipment costs, etc.). However, although this polyimide-fluororesin mixed liquid was fully usable as a normal paint, it still had the non-sticky or non-adhesive properties peculiar to PTFE, and in the sense that it was unable to go beyond this property range, it was far from the high tackiness and adhesion that the inventors had envisioned. For this reason, this polyimide-fluororesin mixed liquid was not satisfactory as a high-performance paint that surpassed the conventional technology that the inventors had envisioned as their ideal.

[0005] Furthermore, the present inventors have reconsidered the composition of materials from every angle with the aim of improving the adhesive and bonding properties of the "polyimide-fluororesin mixture". As a result, they have made black tourmaline, pink tourmaline, hexagonal stones, etc., which are natural ores with electrical potential, into powders with a particle size of 3 μm or less, and then mixed them with a dispersion containing PI and PTFE to prepare a new polyimide-fluororesin mixture, and as a result, they have succeeded in developing a paint with (-)(+) electrical potential (Patent Document 3). As far as the present inventors know, this was the first time in the world that such a paint has been successfully developed. In an evaluation after baking at 380°C, this paint achieved a level of complete adhesion and bonding that far exceeded that of conventional paints. This paint is on the market under the trade name Quatlon (registered trademark). This paint exhibits excellent performance such as outstanding thermal conductivity, insulation, chemical resistance, and heat resistance, and its uses go beyond the scope of a simple paint, and it is attracting attention as a substitute material for all coating materials. For example, just a few examples of products in which Quattron (registered trademark) is used as a material include Teflon (registered trademark) coatings for frying pans, nuts and bolts for insulating parts, and air conditioner filters. All of these prototypes demonstrated outstanding performance far surpassing that of conventional products. Therefore, the applicants began to build a manufacturing system for mass production of Quattron (registered trademark) and its distribution system in order to further promote product development and mixing using Quattron (registered trademark).

[0006] However, the inventors discovered that there was room for improvement in the conventional manufacturing method of Quattron (registered trademark). As mentioned above, this paint / coating agent can form the strongest coating film once it is finally formed into a coating film, but a new problem was highlighted in that an aqueous dispersion is used as a raw material.

[0007] Quatlon® is a paint or coating raw material composition that contains three essential components: a polyimide precursor (polyamic acid (PIA)) or polyimide-containing dispersion, an aqueous PTFE dispersion, and a polar crystal powder (particle size 3 μm or less). This conventional Quatlon® formulation is referred to as "aqueous Quatlon®" in this specification. If aqueous Quatlon® is used in a relatively small amount (e.g., several liters), under relatively mild temperature conditions, and within a relatively short period of time (e.g., within two weeks), there is no problem and the invention described in Patent Document 3 can be easily implemented. However, it has become clear that there are the following problems when preparing an aqueous dispersion of polyamic acid as a raw material for mass production of Quatlon®.

[0008] 1. Settling of Dispersion Aqueous Quattron (registered trademark) is typically shipped in 18-liter plastic cans, similar to other industrial materials. Although this aqueous dispersion is a uniform dispersion at the time of production, precipitation of the components occurs over time (particularly polar crystalline components are prone to precipitation). Quattron (registered trademark) in which precipitation has occurred cannot be used as a raw material for paints / coatings. If a dispersion in which precipitation has occurred is used as is, the concentration will be lower than that at the time of production by the amount of precipitation, so the Quattron (registered trademark) formulation must be stirred again by a propeller stirring operation or the like. The expiration date of new Quattron (registered trademark) is about two months even when stored at a cool temperature (below 20°C). If the storage temperature is high, the problem of precipitation may occur even before two months. Thus, in the current situation, it is natural that aqueous Quattron (registered trademark) must be stirred before use, which is a huge burden for users. 2. Transportation issues Quattron (registered trademark), an aqueous dispersion, is disadvantageous in terms of mass transportation and has limitations. In particular, when shipping overseas, the use of refrigerated containers is essential to meet the above-mentioned storage conditions. If the shipping period is more than two months, differential mixing operations are unavoidable before use, making handling even more difficult. 3.Procedural issues Furthermore, when exporting Quattron (registered trademark), which is an aqueous dispersion, customs procedures tend to be complicated for products that involve the risk of alkaline solutions, although the circumstances vary depending on the situation in each country of export destination.

[0009] As such, Quattron (registered trademark), which is an aqueous dispersion, has problems such as storage stability (quality deterioration over long periods of time, at high temperatures, under oxidative conditions, etc.), transportability (the need for special containers, difficulty in transport due to its weight, the need to take measures against liquid leakage, etc.), and the risks associated with being an aqueous dispersion, which in turn requires measures to deal with the complex customs procedures required for import and export. These inconveniences in handling have been a major obstacle to mass-producing Quattron (registered trademark). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2016-210886 A [Patent Document 2] Patent No. 6704592 [Patent Document 3] Patent No. 6781442 Summary of the Invention [Problem to be solved by the invention]

[0011] The present inventors considered it problematic that the paint (aqueous raw material composition for paint / coating) marketed as Quattron (registered trademark), described in Patent Publication No. 6781442, is currently distributed only in the form of an aqueous dispersion, and conducted research and development to realize a solid composition that would enable the paint to be stored and distributed as a solid-based product and would exhibit performance equal to or better than that of conventional Quattron (registered trademark) paint. As a result, they produced Quattron (registered trademark) paint raw materials as solid (powder, granular) substances using a specific manufacturing method, and when these were reconstituted into an aqueous dispersion at the time of use, they succeeded in obtaining a paint with extremely excellent performance that exhibited performance equal to or better than that of conventional products. [Means for solving the problem]

[0012] That is, the inventors have found that by using an aqueous dispersion containing polyimide, a fluororesin, and polar crystalline fine particles, superior adhesive performance, heat resistance, insulating performance, and the like can be achieved compared to conventional coating agents using a mixture of polyimide and fluororesin, and have completed the present invention.

[0013] The present invention relates to a method for producing an aqueous feedstock composition for paints / coatings, the method comprising the steps of: a) preparing a solid-state polyamic acid-containing composition; b) preparing a solid state polar crystalline composition; and c) mixing the solid-state polyamic acid obtained in step a) and the solid-state polar crystalline composition obtained in step b) Includes.

[0014] In one embodiment, in the above method, the solid-state polyamic acid-containing composition contains 20 to 50% (w / w) of an amine compound.

[0015] In one embodiment, in the method, the amine compound is dimethyldiethanolamine (MDEA).

[0016] In one embodiment, the method includes the step of: d) preparing a fluororesin composition and adding it to the mixture obtained in step c). In one embodiment, in the above method, the fluororesin composition is a dispersion of fluororesin microparticles composed of a polymer or copolymer of a monomer selected from the group consisting of tetrafluoroethylene (PTFE), hexafluoropropylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), vinylidene fluoride and vinyl fluoride, and the polar crystal composition is a dispersion of pink tourmaline or black tourmaline.

[0017] In one embodiment, in the method, the solid state is a powder or granule.

[0018] In one embodiment, the method further comprises the step of: i) processing a solid material containing polyimide into an appropriate size; ii) a step of subjecting the chopped polyimide-containing solid material to an alkali treatment, in which the solid material is dissolved in a treatment liquid containing a basic substance, and the solution is heated for a certain period of time to subject the polyimide in the solution to a partial hydrolysis reaction, thereby producing a polyamic acid-containing aqueous suspension in which a portion of the polyimide is replaced with polyamic acid; iii) adding a pH adjusting liquid to the polyamic acid-containing aqueous suspension to neutralize the polyamic acid-containing aqueous suspension; and iv) subjecting the neutralized polyamic acid-containing aqueous suspension to at least one drying treatment to form polyamic acid-containing granules. The compound is produced by a method comprising the steps of:

[0019] In one embodiment, in the method, the polyimide-containing solid material is a recycled polyimide film, the basic substance is at least one selected from sodium hydroxide or potassium hydroxide, the pH adjusting liquid is at least one selected from hydrochloric acid, sulfuric acid, and citric acid, the drying treatment is selected from spraying, heat drying, and freeze drying, and the paint raw material composition is polyamic acid-containing granules.

[0020] In one embodiment, in the above method, the polyamic acid-containing granules have a specific gravity of 0.25 to 0.45 g / cm 3 and the average particle size is 20 to 25 μm.

[0021] In one embodiment, in the above method, the polar crystalline fine particles are one or more fine particles selected from the group consisting of pink tourmaline and black tourmaline.

[0022] In one embodiment, in the method, the polar crystalline fine particles have a particle size of 3 μm or less.

[0023] In one embodiment, in the above method, the weight ratio of the polyamic acid dispersion liquid / fluororesin is 45 / 55 to 15 / 85.

[0024] In one embodiment, in the above method, a weight ratio of the total of the polyamic acid dispersion and the fluororesin to the polar crystalline fine particles is 100 / 20 to 100 / 40.

[0025] In one embodiment, the method further comprises mixing alumina, or potassium persulfate, or both.

[0026] In one embodiment, the method further comprises mixing at least one component selected from the group consisting of titanium dioxide, epoxy resin, LCP, carbon black carbon fiber, phenoxy resin, PEI (polyethylimide), phenolic resin, lignin, and aggregate (chopped pieces).

[0027] In another aspect, the present invention relates to a method for producing an aqueous paint / coating feed composition, the method comprising: a) preparing a solid-state polyamic acid-containing composition; b) preparing a polar crystalline composition; c) preparing a fluororesin composition; d) storing / transporting the solid-state polyamic acid obtained in step a), the polar crystalline composition obtained in step b), and the fluororesin composition obtained in step c) for a certain time and at a certain temperature; e) after the storage / transportation for the fixed time and at the fixed temperature, adding distilled water to the solid-state polyamic acid in a ratio of the granular polyamic acid / water=1:99 to 50:50 to prepare an aqueous polyamic acid dispersion; f) A step of mixing the aqueous polyamic acid dispersion, the fluororesin composition, and the aqueous polar crystal dispersion and dispersing them homogeneously to obtain an aqueous raw material composition for paint / coating. Includes.

[0028] In one embodiment, in the above method, the solid-state polyamic acid-containing composition contains 20 to 50% (w / w) of an amine compound.

[0029] In one embodiment, in the method, the amine compound is dimethyldiethanolamine (MDEA).

[0030] In one embodiment, in the method, the polar crystalline composition is prepared in a solid state, and prior to step d), the polar crystalline composition is mixed with the solid state polyamic acid-containing composition.

[0031] In one embodiment, in the method, the polar crystalline composition is provided as a liquid dispersion and the fluororesin composition is provided as a liquid.

[0032] In one embodiment, the method further comprises adding an acidic solution in step f) to neutralize the aqueous polyamic acid dispersion, which is alkaline, and the pH of the aqueous polyamic acid dispersion is in the range between 7.5-9.0.

[0033] In one embodiment, in the above method, the acidic solution is at least one selected from hydrochloric acid, sulfuric acid, or citric acid.

[0034] In one embodiment, in the process, step a) is carried out in one stage in a fluid bed granulator dryer.

[0035] In one embodiment, the method wherein the period of storage / transport is two months or longer.

[0036] In one embodiment, in the above method, the fluororesin composition is a dispersion of fluororesin microparticles composed of a polymer or copolymer of a monomer selected from the group consisting of tetrafluoroethylene (PTFE), hexafluoropropylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), vinylidene fluoride and vinyl fluoride, and the polar crystal composition is a dispersion of pink tourmaline or black tourmaline.

[0037] In one embodiment, in the method, the solid state is a powder or granule.

[0038] In one embodiment, the method further comprises the step of: i) processing a solid material containing polyimide into an appropriate size; ii) a step of subjecting the chopped polyimide-containing solid material to an alkali treatment, in which the solid material is dissolved in a treatment liquid containing a basic substance, and the solution is heated for a certain period of time to subject the polyimide in the solution to a partial hydrolysis reaction, thereby producing a polyamic acid-containing aqueous suspension in which a portion of the polyimide is replaced with polyamic acid; iii) adding a pH adjusting liquid to the polyamic acid-containing aqueous suspension to neutralize the polyamic acid-containing aqueous suspension; and iv) subjecting the neutralized polyamic acid-containing aqueous suspension to at least one drying treatment to form polyamic acid-containing granules. The compound is produced by a method comprising the steps of:

[0039] In one embodiment, in the method, the polyimide-containing solid material is a recycled polyimide film, the basic substance is at least one selected from sodium hydroxide or potassium hydroxide, the pH adjusting liquid is at least one selected from hydrochloric acid, sulfuric acid, and citric acid, the drying treatment is selected from spraying, heat drying, and freeze drying, and the paint raw material composition is polyamic acid-containing granules.

[0040] In one embodiment, in the above method, the polyamic acid-containing granules have a specific gravity of 0.25 to 0.45 g / cm 3 and the average particle size is 20 to 25 μm.

[0041] In one embodiment, in the above method, the polar crystalline fine particles are one or more fine particles selected from the group consisting of pink tourmaline and black tourmaline.

[0042] In one embodiment, in the method, the polar crystalline fine particles have a particle size of 3 μm or less.

[0043] In one embodiment, in the above method, the weight ratio of the polyamic acid dispersion liquid / fluororesin is 45 / 55 to 15 / 85.

[0044] In one embodiment, in the above method, a weight ratio of the total of the polyamic acid dispersion and the fluororesin to the polar crystalline fine particles is 100 / 20 to 100 / 40.

[0045] In one embodiment, the method includes alumina, or potassium persulfate, or both.

[0046] In one embodiment, the method further comprises at least one component selected from the group consisting of titanium dioxide, epoxy resin, LCP, carbon black carbon fiber, and aggregate (chopped pieces).

[0047] The present invention also relates to a method for producing an aqueous paint / coating feedstock composition, the method comprising: a) a step of heating the aqueous polyamic acid dispersion under reduced pressure while mixing it with an alkaline solution to evaporate water and process it into a solid state; b) further drying the solid-state polyamic acid obtained in step a) to prepare a granular polyamic acid; c) separately preparing a fluororesin composition and a polar crystalline composition; d) storing / transporting the solid-state polyamic acid obtained in step a) and the fluororesin composition and aqueous polar crystalline composition obtained in step c) for a certain time and at a certain temperature; e) after the storage / transportation for the given time and at the given temperature, adding distilled water to the granular polyamic acid in a ratio of the granular polyamic acid / water=1:99 to 50:50 to prepare an aqueous polyamic acid dispersion; f) mixing the aqueous polyamic acid dispersion, the fluororesin composition, and the aqueous polar crystal dispersion, and dispersing them homogeneously to obtain an aqueous raw material composition for paint / coating.

[0048] In one embodiment, the method includes a step of further adding an acidic solution to neutralize the aqueous polyamic acid dispersion when mixing the alkaline solution in step a).

[0049] In one embodiment, in the method, steps a) and / or b) are carried out in one step in a fluid bed granulator dryer.

[0050] In one embodiment, the method wherein the period of storage / transport is two months or longer.

[0051] In one embodiment, in the method, the fluororesin composition is a PTFE dispersion and the polar crystalline composition is a tourmaline dispersion.

[0052] In one embodiment, the method further comprises, after step c), step c2), in which the PTFE dispersion is processed into a solid state by evaporating water, or the tourmaline dispersion is processed into a solid state by evaporating water.

[0053] In one aspect, the present invention provides a method for producing an aqueous paint / coating feedstock composition, comprising the steps of: a) separately preparing an aqueous polyimide precursor dispersion, an aqueous fluororesin dispersion, and an aqueous polar crystal dispersion; b) mixing the aqueous polyimide precursor dispersion obtained in the above step a), the aqueous PTFE dispersion, and the aqueous polar crystal dispersion to prepare an aqueous raw material composition; c) a step of heating the aqueous raw material composition obtained in the step b) under reduced pressure while mixing it with an alkaline solution to evaporate water and process it into a solid state; d) further drying the raw material composition processed into a solid state obtained in step c) to prepare a granular raw material composition; and e) storing / transporting the solid-state raw material composition obtained in step d) for a certain period of time at a certain temperature; f) after the storage / transportation for the certain period of time, distilled water is added to the solid-state raw material composition so that the paint raw material composition / water ratio is 1:99 to 50:50, and the solid-state raw material composition is further dispersed homogeneously to obtain an aqueous paint / coating raw material composition that has been converted from a solid state to an aqueous state.

[0054] In a preferred embodiment, the polyimide precursor dispersion contains polyimide and polyamic acid as the polyimide precursor, the fluororesin is PTFE, and the solid state is in a powder or granular form.

[0055] In another aspect, the present invention relates to a solid state composition made by the above-described method of manufacture. The solid state composition comprises: i) Polyimide precursor dispersion ii) fluororesin particles, and iii) Polar crystal fine particles It is characterized by containing a component derived from.

[0056] In one aspect, the present invention provides a method for producing an aqueous paint / coating feedstock composition, comprising the steps of: a) separately preparing an aqueous polyimide precursor dispersion, an aqueous fluororesin dispersion, and an aqueous polar crystal dispersion; b) mixing the aqueous polyamic acid dispersion and the aqueous polar crystal dispersion obtained in the above step a) to prepare an aqueous raw material composition; c) a step of heating the aqueous raw material composition obtained in the step b) under reduced pressure while mixing it with an alkaline solution to evaporate water and process it into a solid state; d) further drying the raw material composition processed into a solid state obtained in step c) to prepare a granular raw material composition; and e) storing / transporting the solid-state raw material composition obtained in step d) for a certain period of time at a certain temperature; f) after the storage / transportation for the certain period of time, distilled water is added to the solid-state raw material composition so that the paint raw material composition / water ratio is 1:99 to 50:50, and the solid-state raw material composition is further dispersed homogeneously to obtain an aqueous paint / coating raw material composition that has been converted from a solid state to an aqueous state.

[0057] In a preferred embodiment, the polyimide precursor dispersion contains polyimide and polyamic acid as the polyimide precursor, the fluororesin is PTFE, and the solid state is in a powder or granular form.

[0058] In another aspect, the present invention relates to a solid state composition made by the above-described method of manufacture. The solid state composition comprises: i) a polyimide precursor dispersion, and ii) Polar crystal fine particles It is characterized by containing a component derived from.

[0059] In another aspect, the present invention provides a method for producing an aqueous paint / coating feedstock composition, comprising the steps of: a) a step of heating the aqueous polyimide precursor dispersion under reduced pressure while mixing it with an alkaline solution to evaporate water and process it into a solid state; b) further drying the solid-state polyimide precursor composition obtained in step a) to prepare a final solid-state polyimide precursor composition; c) separately preparing an aqueous fluororesin dispersion and an aqueous polar crystal dispersion; d) storing / transporting the solid-state polyimide precursor obtained in the above step a) and the aqueous fluororesin dispersion and aqueous polar crystal dispersion obtained in the above step c) for a certain period of time at a certain temperature; e) after the storage / transportation for the certain period of time, adding distilled water to the solid-state polyimide precursor so that the ratio of the solid-state polyamic acid to water is 1:99 to 50:50, thereby reconstituting an aqueous polyamic acid dispersion; f) A step of mixing the aqueous polyamic acid dispersion, the aqueous fluororesin dispersion, and the aqueous polar crystal dispersion, and dispersing them homogeneously to obtain an aqueous raw material composition for paint / coating. The present invention relates to a method comprising the steps of:

[0060] In a preferred embodiment, the polyimide precursor dispersion contains polyimide and polyamic acid as the polyimide precursor, the fluororesin is PTFE, and the solid state is in a powder or granular form.

[0061] In a preferred embodiment, the method according to claim 1 further comprises the step of adding an acidic solution to neutralize the aqueous polyamic acid dispersion when mixing the alkaline solution in step a).

[0062] In one embodiment, the polar crystalline fine particles are one or more fine particles selected from the group consisting of pink tourmaline and black tourmaline.

[0063] In one embodiment, the polyimide precursor is a polyamic acid.

[0064] In one embodiment, the polar crystalline fine particles have a particle size of 3 μm or less.

[0065] In one embodiment, the weight ratio of the polyamic acid dispersion liquid to the fluororesin is 45 / 55 to 15 / 85.

[0066] In one embodiment, the weight ratio of the total of the polyamic acid dispersion and the fluororesin to the polar crystalline fine particles is 100 / 20 to 100 / 40.

[0067] In one embodiment, the fluororesin is a fluororesin fine particle made of a polymer or copolymer of a monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), vinylidene fluoride, and vinyl fluoride. Preferably, the fluororesin is polytetrafluoroethylene (PTFE). Effect of the Invention

[0068] According to the present invention, there is provided a solid-state raw material composition that can completely reproduce the performance of an aqueous dispersion as a paint or coating agent, which contains three components: a conventional polyimide precursor (e.g., polyamic acid), a fluororesin (e.g., PTFE), and an aqueous polar crystal (e.g., tourmaline). This solid state is in the form of powder or granules. The solid-state raw material composition of the present invention has the remarkable effects of (1) avoiding the problem of quality deterioration caused by precipitation of dispersion components, (2) eliminating the problems of cost and complexity of transportation caused by the large weight and bulk, which were problems associated with conventional aqueous raw material compositions, and (3) simplifying customs procedures for import and export in the case of aqueous solutions. [Brief description of the drawings]

[0069] [Figure 1] 1 is a chart showing a process outline of a method for producing Quattron® aqueous dispersion. [Diagram 2] 1 is a chart showing problems that may occur during storage and shipping of Quattron (registered trademark) aqueous dispersion. [Diagram 3] 1 is a chart showing the development strategy for an instant formulation of Quattron® aqueous dispersion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0070] Here, the characteristics of Quattron (registered trademark), current problems, and an overview of means for solving these problems will be described with reference to FIGS.

[0071] Figure 1 shows the structural characteristics of Quattron (registered trademark) and an overview of its use process. Quattron (registered trademark) is supplied as an aqueous dispersion containing three types of polyamide precursor, fluororesin, and polar crystals. The process from manufacturing to use of Quattron (registered trademark) is as follows: raw material preparation → aqueous dispersion preparation → storage and shipping → painting and coating work at the site (by the user) → high-temperature baking → coating film formation. Quattron used in this procedure can produce ultra-high performance films, but problems caused by supplying it in the form of an aqueous dispersion at the storage and shipping stages have become clear (Figure 2). First of all, since Quattron (registered trademark) is supplied as an alkaline solution, there is a risk that the liquid will leak during transportation due to damage to the container or improper management, which may cause problems during long-distance transportation and import / export. In addition, various procedures, including paperwork, may be complicated when importing and exporting due to the handling of hazardous materials. Furthermore, transporting a liquid formulation would involve an enormous weight, and therefore the handling of the liquid formulation would be very disadvantageous in terms of labor and cost.

[0072] However, the most problematic aspect of liquid preparations is the performance of the preparation, and Quattron (registered trademark) has problems with its performance as a dispersion liquid with long-term storage. That is, it has been found that the dispersion state becomes non-uniform after a certain period of time has passed since production, and polar crystalline components, in particular, precipitate. The expiration date of such Quattron (registered trademark) dispersion liquid is about two months after production. Even if the dispersion state of Quattron (registered trademark) dispersion liquid has deteriorated and components have precipitated after about two months from production, it is not difficult to restore the dispersion state by re-stirring. However, it is expected that this will be a very cumbersome task for users who perform painting / coating work on site, and in order to overcome this situation, we have attempted to solve such problems by supplying part or all of Quattron (registered trademark) in a solid state (powder or granules) rather than a dispersion liquid.

[0073] The present inventors considered that if at least the polyimide precursor (1) of the components of Quattron (registered trademark) could be supplied in a solid state (powder or granules), all of the above problems would be solved. The user simply needs to prepare a dispersion by adding water to the polyimide precursor (1) at the work site. In this specification, such a dispersion may be referred to as an "instant dispersion" or "immediately prepared dispersion". The immediately prepared dispersion may contain not only the polyimide precursor (1) but also, optionally, the fluororesin (2) and / or the polar crystal (3) in advance, or the fluororesin (2) and / or the polar crystal (3) may be provided as an individually prepared aqueous dispersion and stirred with the polyimide precursor (1) to provide a fresh dispersion. Alternatively, the polyimide precursor (1) may be provided as a solid, and a dispersion may be prepared by mixing and stirring immediately before use.

[0074] Production of polyamic acid-containing solid-state raw material composition The solid-state raw material-containing composition containing a polyimide precursor (polyamic acid (polyamic acid, polyamic acid)) of the present invention contains polyimide and polyamic acid. The solid-state raw material composition of the present invention contains a polyimide obtained by partially hydrolyzing a polyimide using a polyimide powder as a raw material to obtain a polyamic acid. The ratio of polyimide to polyamic acid in the solid-state raw material composition of the present invention is about 50:50 to about 10:90. The granules of the present invention have a particle size distribution of, for example, about 1 to 500 μm, and an average particle size of 100 μm or less, preferably 20 μm or less, and most preferably 10 μm or less. These particle size distributions and average particle sizes can be measured by a method known in the art, for example, a laser diffraction / scattering method using a particle size analyzer.

[0075] The polyamic acid-containing solid state raw material composition of the present invention is in a solid state, for example, in a powder or granular form, and does not substantially contain water. However, the solid state in the present invention does not mean that it does not contain any liquid components. For example, even if the polyamic acid coexists with diethylethanolamine (MDEA), which is included to dissolve the polyamic acid in a later process, it is clearly distinguished from the liquid state and is included in the solid state of the present invention. The polyamic acid-containing raw material composition of the present invention includes polyimide and polyamic acid, but may also include other additives. Examples of additives include polysaccharides or their derivatives or related substances, such as cellulose or lignin.

[0076] The polyamic acid-containing granules of the present invention are produced as follows. First, a solid polyimide is prepared as a raw material. This polyimide may be a recycled waste product or a newly synthesized polyimide film. Next, the raw polyimide is dissolved (hydrolyzed) in a treatment liquid containing a basic substance. The treatment liquid is a water-based solution, and at least one of an alkali metal or its salt can be used as the basic substance, for example, a strongly basic substance such as potassium hydroxide or sodium hydroxide can be used. In particular, the use of caustic soda (sodium hydroxide) is preferable in terms of ease of availability. In addition, it is also preferable to use potassium hydroxide in terms of being able to obtain polyimide powder with little discoloration from the raw polyimide. The treatment liquid can be prepared by dissolving a basic substance in water as a solvent. Here, the basic substance can be dissolved in an amount of 10 to 50 parts by weight, preferably 10 to 40 parts by weight, per 100 parts by weight of the solvent, and the pH of the treatment liquid can be set to 10 to 14. This allows the raw polyimide to be well dissolved. Furthermore, as the solvent for the treatment liquid, an organic solvent such as glycerin may be added as necessary to form a mixed solvent of water and glycerin.

[0077] The raw polyimide dissolved in the treatment liquid may be any polyimide containing an imide bond as a repeating unit in the main chain of the polymer, for example, an aromatic polyimide in which an aromatic compound is directly linked by an imide bond. The raw polyimide may be any polyimide-containing industrial waste such as cutting waste and defective products generated in the process of manufacturing a polyimide film, or waste polyimide products, but it is preferable to use cutting waste and defective products of polyimide films with few impurities. The raw polyimide is dissolved by immersing in the treatment liquid. In this case, the polyimide can be mixed in a ratio of 40 to 120 parts by weight, preferably 40 to 80 parts by weight, per 100 parts by weight of the solvent of the treatment liquid, and the temperature of the treatment liquid can be 70 to 100°C, preferably 70 to 90°C, and the treatment time can be 50 to 100 minutes. Stirring may be performed as necessary. This allows the raw polyimide to be dissolved well.

[0078] By such an operation, the imide ring part of the polyimide is attacked by alkali and hydrolyzed to a structure containing amine and carboxylic acid, and a polyamic acid-containing solution is generated. Since this polyamic acid is a raw material for the future production of polyimide again, the conditions of the alkali treatment should be adjusted so that the granules of the present invention contain as much polyamic acid as possible, but it is necessary to avoid the reaction proceeding excessively, which leads to low molecular weight.

[0079] Next, the obtained polyamic acid-containing solution is cooled as necessary (for about 10 minutes), and then an acidic substance is added to the polyamic acid-containing solution to perform neutralization treatment, and the dissolved polyamic acid fine particles are precipitated. Here, as the acidic substance, a strong acid such as hydrochloric acid or a weak acid such as phosphoric acid can be used. Preferably, acetic acid is preferably used. Also, an organic acid such as citric acid may be used. The amount of the acidic substance added can be 10 to 50 parts by weight, preferably 10 to 40 parts by weight, relative to 100 parts by weight of the solvent of the above-mentioned treatment liquid, and this ensures the precipitation of polyimide fine particles. Also, by adding the acidic substance, the pH of the treatment liquid in which the polyimide is dissolved can be made close to neutral, and for example, the pH of the solution after the addition of the acidic substance is 7 to 8. Also, the pH of the solution can be adjusted to an acidic range, for example, 4 to 6.

[0080] Next, the neutralized treatment liquid from which the polyamic acid fine particles have precipitated is filtered to separate a powder consisting of the solid polyamic acid fine particles. A filter press or the like can be used for the filtration. This filtration can separate the solid polyamic acid fine particles from the liquid portion containing the alkali metal derived from the basic substance. Next, the separated polyamic acid fine particle powder is washed with water. This water washing can remove (reduce) the alkali metal derived from the basic substance that remains in the polyimide powder by adhering to the polyamic acid fine particles. The water washing can be performed by repeating (e.g., 5 to 10 times) a process of putting the filtered solid into water and stirring it until the residual amount of the alkali metal becomes 1% or less. More specifically, for example, the water washing can be performed by mixing 50 parts by weight of the separated polyimide fine particle powder with 100 liters of water at a temperature of 60°C and stirring for 30 minutes, which is one process.

[0081] Thereafter, the mixture is dehydrated under reduced pressure and dried at a temperature of 70 to 80° C. for about 12 hours to obtain polyamic acid-containing granules having a moisture content of 0.5% or less. The polyamic acid-containing granules have an average particle size of 25 μm or less.

[0082] In the present invention, the polyamic acid-containing granules prepared as described above can be suitably used as a polyimide precursor. The polyamic acid-containing composition may be used in a solid state, or may be used in the form of a dispersion provided as a commercially available product, from which water is removed to form a solid state.

[0083] Polyimide (PI) is a resin made of a polymer that has imide bonds in its molecular structure. Polyimide can be synthesized, for example, by a general synthesis method shown in the following formula: In this synthesis method, equimolar amounts of tetracarboxylic dianhydride and diamine are polymerized as raw materials to obtain polyamic acid, which is a precursor of polyimide.

[0084] [ka] This polyamic acid is heated to 200°C or higher, or a catalyst is used to promote a dehydration and cyclization (imidization) reaction to obtain polyimide. When a catalyst is used, amine compounds are often used, and a carboxylic acid anhydride may also be used in combination as a dehydrating agent to quickly remove the water generated by the imidization.

[0085] [ka]

[0086] In this specification, a compound that can be a raw material for polyimide is referred to as a polyimide precursor. The polyimide precursor includes polyamic acid (polyamic acid, polyamic acid). The polyimide precursor may also include a substance described in FIG. 1 of International Publication No. 2012 / 096374 or in paragraph

[0024] of JP-A-2017-165990. The polyimide precursor is, for example, as shown below.

[0087] [ka]

[0088] [ka] (In the formula, the symbol X is an alkali metal (lithium / Li, sodium / Na, potassium / K, rubidium / Rb, or cesium / Ce), the subscripts n and l are symbols indicating the amount (number of moles) of polyamic acid structures present on both sides of the polyimide structure, and are usually values ​​within a range of 0.1 to 0.8, and the subscript m is a symbol indicating the amount (number of moles) of polyimide structures present, and are usually values ​​within a range of 0.2 to 0.9.)

[0089] The polyimide used in the mixed aqueous dispersion is not particularly limited, and may be, for example, a resin made of a high molecular weight polymer obtained by the reaction of an aromatic tetravalent carboxylic acid anhydride such as pyromellitic anhydride, and any polyimide that is obvious to a person skilled in the art may be used. The polyimide used in the mixed aqueous dispersion may be recycled by crushing used polyimide, or may be unused. The shape of the polyimide is not particularly limited, but from the viewpoint of easily maintaining a suspended and dispersed state in the mixed aqueous dispersion for a long period of time, it is preferable that the polyimide is a fine particle with a particle size in the range of 1 μm to 100 μm. The content of the polyimide is preferably 5% by weight to 40% by weight, more preferably 10% by weight to 30% by weight, or more preferably 10% by weight to 20% by weight, based on the mixed aqueous dispersion.

[0090] The mixed aqueous dispersion of the present invention preferably contains polyamic acid, which is a precursor of polyimide. Polyamic acid can be dehydrated and cyclized (imidized) by heating at 200° C. or higher. This imidization process allows the polyamic acid-containing mixed aqueous dispersion to form a stronger coating film or coating.

[0091] The mixed aqueous dispersion of the present invention may contain one or more polyimide analogues selected from polyamic acid (polyamic acid, polyamic acid), polyamideimide, or polyamide ester as a precursor of polyimide. These polyimide analogues have a positive effect on the adhesive performance of the mixed aqueous dispersion and are essential components for producing a coating film with high heat resistance and high strength. Preferably, the mixed aqueous dispersion of the present invention contains a polyimide dispersion containing polyamic acid.

[0092] Thus, it should be understood that the term polyimide is used in the broad sense of the present specification to include polyimides contained in the mixed aqueous dispersion as well as polyimide precursors and polyimide analogues.

[0093] Examples of preparations containing polyimide as a raw material that are preferably used in the present invention include W-20 manufactured by Nakada Coating Co., Ltd. and PIA Powder manufactured by PI Chemical Industry Co., Ltd., but are not limited thereto. Such formulations may also contain phosphoric acid, ethanol dispersions, amines, propylene glycol, nonionic components (neutral additives), carbon black as a coloring component, and the like.

[0094] In this specification, the polar crystal refers to a crystal having a positive electrode (+) on one side and a negative electrode (-) on the opposite side. The polar crystal is always in an unstable state (electric potential difference), and due to this electric potential difference, electrons are constantly emitted and flow from the negative electrode to the positive electrode. In this specification, the polar crystal fine particles are one or more selected from the group consisting of pink tourmaline, black tourmaline, and hexagonal stone, but are not limited to these.

[0095] One of the best known polar crystals is tourmaline, which has the chemical formula XY3Al6(BO3)3SiO 18 It is a crystal composed of (O,OH,F)4, of which dravite (magnesium oxide) NaMg3Al6(BO3)3Si6O18 (OH)4, elbaite (sphaerite) Na(Li,Al)3Al6(BO3)3Si6O 18 (OH)4, Schorl (iron tourmaline) NaFe3Al6(BO3)3Si6O 18 (OH)4, uviteCaMg3(Al5Mg)(BO3)3Si6O 18 (OH,F)4 is what is called tourmaline.

[0096] Tourmaline is said to have been excavated in Ceylon, Sri Lanka, in 1703 and brought to Europe. Later, in 1880, Pierre Curie, who was awarded the Nobel Prize in Physics, discovered that when tourmaline crystals are subjected to external pressure, an electric charge is generated on the crystal surface. It was also discovered that an electric charge is generated when thermal energy is applied to tourmaline. The phenomenon that occurs when pressure is applied to tourmaline is called piezoelectricity, and when heat is applied, electrons are separated at both poles of the crystal, generating positive and negative electricity, called pyroelectricity. When pressure or heat is applied to tourmaline, positive and negative electrodes are generated at both poles of the stone, generating electricity. The positive pole attracts electrons, and the negative pole releases electrons outside the crystal (in water, on the surface of the skin, and other places where electricity flows easily). The water generated and the moisture in the air are electrolyzed to generate hydroxyl ions (H3O 2- ) which releases negative ions.

[0097] The present invention uses polar crystals to obtain coating agents and paints with excellent coating properties, which is presumably due to the electrical properties of tourmaline as described above, but is not limited thereto. The polar crystals of the present invention can be prepared by pulverizing polar crystal ores into fine particles (e.g., particle size 10 μm or less, 5 μm or less, 3 μm or less, or 1 μm or less), which can be used as an aqueous dispersion. The aqueous dispersion of the polar crystals is, for example, a suspension with a concentration of 5% by weight to 40% by weight.

[0098] The fluororesin used in the mixed aqueous dispersion is not particularly limited, and may be, for example, resin fine particles made of a polymer or copolymer of a monomer selected from tetrafluoroethylene (polytetrafluoroethylene, PTFE), hexafluoropropylene, chlorotrifluoroethylene, perfluoro (alkyl vinyl ether), vinylidene fluoride, vinyl fluoride, polyether ether ketone (PEEK), and polyether ketone ketone (PEKK). Among these, those that disperse in water are used for preparing the mixed aqueous dispersion.

[0099] The shape of the fluororesin is not particularly limited, but from the viewpoint of being able to easily maintain a suspended and dispersed state in the mixed aqueous dispersion for a long period of time, it is preferable that the fluororesin be in the form of fine particles with an average molecular weight of 1×10 4 ~1×10 7 and the particle size is preferably in the range of 100 to 500 nm.

[0100] The content of the fluororesin (content of fluororesin solids) is preferably 20% by weight to 60% by weight, and more preferably 35% by weight to 45% by weight, based on the mixed aqueous dispersion.

[0101] As described above, the fluororesin used in the mixed aqueous dispersion is not particularly limited. For example, A-1: ​​Polyflon D-111 (PTFE solid content: 55 to 65% by weight, average molecular weight: 2 × 10 4 ~1×10 7 , particle size: 0.25 μm, pH: 9.7), A-2: Asahi Glass, AD911E (PTFE solid content: 60% by weight, average molecular weight: 2 × 10 4 ~1×10 7 , particle size: 0.25 μm, pH: 10), A-3: Mitsui Fluoro, 31-JR (PTFE solid content: 60% by weight, average molecular weight: 2 × 10 4 ~1×10 7 , particle size: 0.25 μm, pH: 10.5) etc. The particle size refers to the average particle diameter of the PTFE primary particles.

[0102] The fluororesin used in the mixed aqueous dispersion may be a PTFE dispersion (dispersion), and this PTFE dispersion may contain a neutral surfactant, a nonionic surfactant, an amine, a glycol, etc. As such a PTFE dispersion, PTFE-D (manufactured by Daikin Industries, Ltd.) and the like are preferably used.

[0103] The mixed aqueous dispersion may contain alumina. In the present invention, alumina includes fine particles of aluminum oxide such as aluminum oxide (compositional formula: Al2O3), amorphous aluminum hydroxide, gibbsite, bialite (compositional formula: Al(OH)3), and / or boehmite or diaspore (compositional formula: AlOOH).

[0104] From the viewpoint that alumina can easily maintain a suspended and dispersed state in the mixed aqueous dispersion for a long period of time, it is desirable that the particle size of the fine particles is in the range of 5 to 4500 nm.

[0105] The content of alumina is preferably 1 to 10% by weight, more preferably 3 to 7% by weight, relative to the mixed aqueous dispersion. This is because if the content of alumina is less than 1% by weight, the adhesive performance and heat resistance performance attributable to alumina cannot be sufficiently imparted to the mixed aqueous dispersion, and if the content exceeds 10% by weight, no further effects can be expected.

[0106] By including alumina in the mixed aqueous dispersion, the mixed aqueous dispersion can be provided with excellent adhesive properties and heat resistance.

[0107] The shape of the alumina in the alumina sol is not particularly limited, and may be any shape, such as plate-like, columnar, fibrous, or hexagonal plate-like. When the alumina sol is fibrous, the alumina is a fibrous crystal of alumina. More specifically, examples of the alumina include alumina fibers formed of anhydrous alumina, and alumina hydrate fibers formed of alumina containing hydrate.

[0108] The alumina used in the mixed aqueous dispersion is not particularly limited, and examples thereof include Aluminasol-10A (weight% in terms of Al2O3: 9.8 to 10.2, particle size in nm: 5 to 15, viscosity at 25°C, mPa / s: <50, pH: 3.4 to 4.2, manufactured by Kawaken Fine Chemicals), Aluminasol-A2 (weight% in terms of Al2O3: 9.8 to 10.2, particle size in nm: 10 to 20, viscosity at 25°C, mPa / s: <200, pH: 3.4 to 4.2, manufactured by Kawaken Fine Chemicals), Aluminasol-CSA-110AD (weight% in terms of Al2O3: 6.0 to 6.4, particle size in nm: 5 to 15, viscosity at 25°C, mPa / s: <200, pH: 3.4 to 4.2, manufactured by Kawaken Fine Chemicals), and Aluminasol-CSA-110AD (weight% in terms of Al2O3: 6.0 to 6.4, particle size in nm: 5 to 15, viscosity at 25°C, Examples of the alumina sol include Alumina Sol F1000 (weight % Al2O3 equivalent: 4.8-5.2, particle size nm: 1400, viscosity at 25°C, mPa / s: <1000, pH: 2.9-3.3, manufactured by Kawaken Fine Chemicals), Alumina Sol F3000 (weight % Al2O3 equivalent: 4.8-5.2, particle size nm: 2000-4500, viscosity at 25°C, mPa / s: <1000, pH: 2.7-3.3, manufactured by Kawaken Fine Chemicals), and any alumina sol that is obvious to a person skilled in the art can be used.

[0109] Although the alumina used in the mixed aqueous dispersion is not particularly limited as described above, it is preferable to use fine particles of alumina having a hydroxyl group (OH group). By using alumina having an OH group, the chemical bonding strength (adhesive strength) of the OH group of alumina is increased, so that the mixed aqueous dispersion can be provided with better adhesive performance.

[0110] Also, instead of or in addition to alumina, other metal oxide fine particles may be added. As the other metal oxide fine particles, there is no particular limitation, but titanium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, cerium oxide, tin oxide, etc. can be used. By adding these metal oxide fine particles instead of or in addition to alumina, it is possible to produce a polyimide-fluororesin-polar crystalline fine particle mixed aqueous dispersion having coating properties different from those when only alumina is added.

[0111] The mixed aqueous dispersion may contain potassium persulfate. Potassium persulfate is a compound containing OH groups, so it can increase the number of OH groups contained in the mixed aqueous dispersion, and the chemical bonding strength (adhesive strength) due to the OH groups increases, so that the mixed aqueous dispersion can be imparted with excellent adhesiveness. The content of potassium persulfate is preferably 0.1% by weight to 5% by weight, and more preferably 1% by weight to 3% by weight, relative to the mixed aqueous dispersion. This is because if the content of potassium persulfate is less than 0.1% by weight, the adhesive performance attributable to potassium persulfate cannot be sufficiently imparted to the mixed aqueous dispersion, and even if the content exceeds 5% by weight, no further effect can be expected.

[0112] Alternatively, instead of or in addition to potassium persulfate, other compounds containing OH groups may be added, such as, but not limited to, acetic acid, benzoic acid, phenylphosphonic acid, or benzoyl compounds.

[0113] The mixed aqueous dispersion may further contain PVA (polyvinyl alcohol). PVA has the structural formula shown below and contains many OH groups. Therefore, the number of OH groups contained in the mixed aqueous dispersion can be increased, and the chemical bonding strength (adhesive strength) due to the OH groups can be increased, thereby imparting excellent adhesiveness to the mixed aqueous dispersion. Furthermore, even after being blended into the mixed aqueous dispersion, PVA remains stable in the mixed aqueous dispersion, and there is little risk of the adhesiveness decreasing. Therefore, the excellent adhesiveness of the mixed aqueous dispersion can be stably maintained for a long period of time. The content of PVA is preferably 0.5% by weight to 10% by weight, more preferably 3% by weight to 6% by weight, based on the mixed aqueous dispersion. This is because if the content of PVA is less than 0.5% by weight, the adhesive performance attributable to PVA cannot be sufficiently imparted to the mixed aqueous dispersion, and if the content exceeds 10% by weight, no further effect can be expected.

[0114] [ka]

[0115] The mixed aqueous dispersion may further contain phosphoric acid. Since phosphoric acid is a compound containing OH groups, it can increase the number of OH groups contained in the mixed aqueous dispersion, which in turn increases the chemical bonding strength (adhesive strength) due to the OH groups, thereby imparting excellent adhesiveness to the mixed aqueous dispersion. The content of phosphoric acid is preferably 0.1% by weight to 5% by weight, more preferably 1% by weight to 3% by weight, based on the mixed aqueous dispersion. This is because if the content of phosphoric acid is less than 0.1% by weight, the adhesive performance attributable to phosphoric acid cannot be sufficiently imparted to the mixed aqueous dispersion, and if the content exceeds 5% by weight, no further effect can be expected.

[0116] Phosphoric acid may be used to pretreat the polyimide for use in the mixed aqueous dispersion. Polyimide is added to phosphoric acid-ethanol containing phosphoric acid, mixed, and then the ethanol is evaporated to obtain a polyimide-phosphoric acid mixed powder. The polyimide-phosphoric acid mixed powder can be dispersed more easily in an aqueous solvent than polyimide alone.

[0117] In addition to the above-mentioned components, the mixed aqueous dispersion may contain other additives to modify the mixed aqueous dispersion. Examples of additives include solvents, tackifiers, plasticizers, curing agents, crosslinking agents, diluents, fillers, thickeners, pigments, stabilizers, adhesion enhancers, flow agents, and defoamers, but are not limited to these. Any additives that are commonly used to modify the properties of the mixed aqueous dispersion and are obvious to those skilled in the art can be used. More specifically, such additives can include titanium oxide, epoxy resins, LCPs, carbon black carbon fibers, phenoxy resins, PEI (polyethylimide), phenolic resins, lignin, and aggregates (chopped pieces).

[0118] The polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion of the present invention may contain a colorant such as carbon black. It is important to maintain the pH of this mixed aqueous dispersion in the neutral range of 7.0 to 8.0. If the pH of this mixed aqueous dispersion is on the acidic side (for example, pH 6.0), heat shock may occur during the formation of a coating film, causing the coating film to crack or solid content to be generated.

[0119] A method for producing a mixed aqueous dispersion of polyimide precursor-fluororesin-polar crystalline fine particles will now be described.

[0120] The method for producing this mixed aqueous dispersion includes the steps of crushing and sieving polar crystalline fine particles to obtain polar crystalline fine particles having a particle size of 3 μm or less, preparing dispersion 1 containing the polar crystalline fine particles, preparing dispersion 2 containing a polyimide precursor or polyimide, preparing dispersion 3 containing a fluororesin, and mixing all of dispersions 1, 2, and 3.

[0121] The method for producing this mixed aqueous dispersion may further include a step of adding potassium persulfate to water to prepare an aqueous potassium persulfate solution, a step of preparing dispersion 4 containing alumina, and a step of mixing all of the above dispersions with the aqueous potassium persulfate solution.

[0122] In another embodiment, the method for producing the mixed aqueous dispersion includes the steps of adding potassium persulfate to water to prepare an aqueous potassium persulfate solution, and mixing a polyimide, a fluororesin, polar crystalline fine particles, alumina, and the aqueous potassium persulfate solution. The method for producing the mixed aqueous dispersion may also include, as a pretreatment step, a step of mixing a polyimide with an ethanol solution of phosphoric acid and then drying the mixture to prepare a polyimide-phosphoric acid mixed powder. In these steps, the mixing method, mixing temperature, and mixing time are not particularly limited, and any mixing method that can produce a mixed aqueous dispersion and has been conventionally used can be used.

[0123] The potassium persulfate aqueous solution is prepared by adding solid potassium persulfate to water. More specifically, potassium persulfate is added to water so that the amount of potassium persulfate is 1% by weight, and then the water is heated to a temperature not to boil to dissolve the potassium persulfate, thereby preparing the potassium persulfate aqueous solution.

[0124] Polyimide may be difficult to dissolve in an aqueous solvent. Therefore, in order to improve the aqueous dispersibility of polyimide, the polyimide may be pretreated before preparing the mixed aqueous dispersion. The pretreatment step includes mixing the polyimide with an ethanol solution of phosphoric acid, and then drying the mixed solution to evaporate water, thereby producing a polyimide-phosphoric acid mixed powder. By using the polyimide-phosphoric acid mixed powder, the aqueous dispersibility of the polyimide can be greatly improved compared to the case where polyimide alone is used, and the mixed aqueous dispersion according to the present invention can be produced more easily. It goes without saying that the mixed aqueous dispersion according to the present invention can be produced without performing this pretreatment step.

[0125] The present solid-state paint / coating raw material composition The aqueous raw material composition for paint / coating of the present invention contains a polyimide precursor (polyamic acid), a fluororesin, and a polar crystal. The aqueous raw material composition for paint / coating of the present invention contains an aqueous polyamic acid dispersion component, an aqueous fluororesin component, and a polar crystal dispersion component. The aqueous raw material composition for paint / coating of the present invention is characterized in that a part or the whole of the mixed aqueous dispersion is dried to a solid state to produce an aqueous raw material composition for paint / coating in a solid state. Preferably, the solid state is a powder or granule.

[0126] In one embodiment, in the aqueous paint / coating raw material composition of the present invention, at least the aqueous polyamic acid dispersion component is supplied in powder or granular form. In another embodiment, in the aqueous paint / coating raw material composition of the present invention, the aqueous polyamic acid dispersion and the aqueous fluororesin (e.g., aqueous PTFE dispersion) components are supplied in powder or granular form. In another embodiment, in the aqueous paint / coating raw material composition of the present invention, at least the aqueous polyamic acid dispersion component and the aqueous polar crystal dispersion component are supplied in powder or granular form. In another embodiment, in the aqueous paint / coating raw material composition of the present invention, the aqueous polyamic acid dispersion component, the aqueous fluororesin (e.g., aqueous PTFE dispersion) component, and the aqueous polar crystal dispersion are all supplied in powder or granular form.

[0127] In one embodiment, the aqueous raw material composition for paint / coating of the present invention is a composition containing an aqueous polyamic acid dispersion component, an aqueous fluororesin (e.g., aqueous PTFE dispersion) component, and / or an aqueous polar crystal dispersion component, and is supplied in powder or granular form. When used as a paint / coating agent, water can be added to the aqueous polyamic acid dispersion component, the aqueous fluororesin dispersion component, and / or the aqueous polar crystal dispersion component to prepare the paint / coating agent. Water is added so that the powder or granule component is 5% to 20%, preferably about 10%. As a specific operation, while stirring the water, powder or granule, which is a composition containing the aqueous polyamic acid dispersion component, the fluororesin dispersion component, and / or the aqueous polar crystal dispersion component of the present invention, is added. Care should be taken not to stir too vigorously to prevent air bubbles from being generated. Preferably, the stirring conditions for the aqueous solution may be, for example, at 5 to 600 rpm (average 240 rpm) using a homogenizer manufactured by Kansai Machinery Co., Ltd. (50 L scale), or at 10 rpm to 15,000 rpm (average 700 to 800 rpm) using a homogenizer manufactured by STM (small capacity, lab scale).

[0128] In one embodiment, the aqueous paint / coating raw material composition of the present invention is such that the aqueous polyamic acid dispersion component and the aqueous polar crystal dispersion component are supplied in powder or granular form, and the fluororesin is supplied as a liquid composition, and when used as a paint / coating agent, the aqueous polyamic acid dispersion component and the aqueous polar crystal dispersion component are prepared as an aqueous dispersion by adding water, and then mixed with the fluororesin supplied as a liquid composition to form the paint / coating agent.

[0129] In one embodiment, the aqueous raw material composition for paint / coating of the present invention is such that the components of the aqueous polyamic acid dispersion are supplied in powder or granular form, and when used as a paint / coating agent, the components of the aqueous polyamic acid dispersion are prepared as an aqueous dispersion by adding water, and then the fluororesin and polar crystals are mixed with this aqueous dispersion to form a paint / coating agent. In this case, the fluororesin and polar crystals may be supplied in a solid state (e.g., powder or granular form) or as a liquid composition (e.g., aqueous dispersion).

[0130] Preferably, the aqueous raw material composition for paint / coating of the present invention is shipped from a manufacturer (e.g., Japan Matex Co., Ltd.) as a powder or granular agent containing the components of the aqueous polyamic acid dispersion, delivered to a paint / coating company, and further prepared as an aqueous dispersion by the company. After that, a fluororesin and polar crystals obtained separately are mixed with this aqueous dispersion to complete the paint / coating agent, which can be used on the spot as a paint / coating agent.

[0131] Alternatively, the aqueous raw material composition for paint / coating of the present invention thus prepared may be shipped from a manufacturer (e.g., Japan Matex Co., Ltd.) as a powder or granular agent, delivered to a paint / coating company, and prepared as an aqueous dispersion by the company. After that, a fluororesin and polar crystals obtained separately are mixed with this aqueous dispersion to complete the paint / coating agent, which can be used on the spot as a paint / coating agent.

[0132] The aqueous paint / coating raw material composition of the present invention was originally prepared and supplied as a liquid in which the aqueous polyimide precursor (polyamic acid), fluororesin, and aqueous polar crystals were uniformly dispersed, but due to the nature of the dispersion liquid, it is difficult to maintain the dispersion state for a long period of time, and there is a possibility that the dispersion state will no longer be uniform. The time until the dispersion state becomes non-uniform varies depending on the storage conditions, but generally, if the dispersion liquid is prepared and thereafter is not stirred, polar crystals such as tourmaline tend to precipitate after a long period of storage in about two weeks. If the polar crystals precipitate, the paint / coating agent will no longer be able to perform as intended, so a uniform dispersion must be prepared again using a stirrer. Stirring may be performed by hand or machine, but it is preferable to use a stirrer to obtain reproducible results and / or to perform efficient work. Preferably, the stirring conditions for the aqueous solution may be, for example, at 5 to 600 rpm (average 240 rpm) using a homogenizer manufactured by Kansai Machinery Co., Ltd. (50 L scale), or at 10 rpm to 15,000 rpm (average 700 to 800 rpm) using a homogenizer manufactured by STM (small capacity, lab scale).

[0133] In preparing the aqueous paint / coating raw material composition of the present invention, in addition to the polyimide precursor, the fluororesin and / or polar crystalline fine particles can also be supplied in powder or granular form. Therefore, the compositions that can be supplied in powder or granular form in preparing the aqueous paint / coating raw material composition of the present invention can be supplied as any of (1) a composition containing a polyimide precursor, (2) a composition containing a polyimide precursor and polar crystalline fine particles, (3) a composition containing a polyimide precursor and a fluororesin, and (4) a composition containing a polyimide precursor, a fluororesin, and polar crystalline fine particles, but are not limited thereto. The polyimide precursor, the fluororesin, and the polar crystalline fine particles that are not included in the powder or granular composition can be added as a liquid or solid formulation when the user prepares the final aqueous paint / coating.

[0134] The mixed powder containing the polyimide precursor, fluororesin, and / or polar crystalline fine particles of the present invention may be produced by preparing the polyimide precursor-fluororesin-polar crystalline fine particles mixed aqueous dispersion according to the present invention in a conventional manner, and then drying the aqueous dispersion, i.e., evaporating the water in the aqueous dispersion. The drying method for producing the mixed powder containing the polyimide precursor, fluororesin, and / or polar crystalline fine particles of the present invention is not particularly limited, and any method may be used as long as it can evaporate the water in the polyimide precursor-fluororesin-polar crystalline fine particles mixed aqueous dispersion according to the present invention to make it into a solid state. For example, a rotary evaporator or a freeze-drying device can be used for such drying. It is preferable to use a freeze-drying device in that it can eliminate the possibility of quality deterioration due to heating.

[0135] The mixed powder containing the polyimide precursor of the present invention, the fluororesin, and / or the polar crystalline fine particles may be produced by preparing a mixed aqueous dispersion containing the polyimide precursor of the present invention and the polar crystalline fine particles according to a conventional method, drying the aqueous dispersion, i.e., evaporating the water in the aqueous dispersion to obtain a solid composition containing the polyimide precursor and the polar crystalline fine particles, and then mixing the solid fluororesin with the solid composition containing the polyimide precursor and the polar crystalline fine particles. The drying method for producing the mixed powder containing the polyimide precursor and the polar crystalline fine particles of the present invention is not particularly limited, and any method may be used as long as it can evaporate the water in the mixed aqueous dispersion of the polyimide precursor and the polar crystalline fine particles of the present invention to make it into a solid state. For example, a rotary evaporator or a freeze-drying device can be used for such drying. It is preferable to use a freeze-drying device in that it can eliminate the possibility of quality deterioration due to heating.

[0136] The mixed powder containing the polyimide precursor, fluororesin, and / or polar crystalline fine particles of the present invention may be produced by preparing a mixed aqueous dispersion containing the polyimide and fluororesin according to the present invention according to a conventional method, drying the aqueous dispersion, i.e., evaporating the water in the aqueous dispersion to obtain a solid composition containing the polyimide precursor and the fluororesin, and then mixing the solid polar crystalline fine particles with the solid composition containing the polyimide precursor and the fluororesin. The drying method for producing the mixed powder containing the polyimide precursor and fluororesin of the present invention is not particularly limited, and any method may be used as long as it can evaporate the water in the mixed aqueous dispersion of the polyimide and fluororesin according to the present invention to make it into a solid state. For example, a rotary evaporator or a freeze-drying device can be used for such drying. It is preferable to use a freeze-drying device in that it can eliminate the possibility of quality deterioration due to heating.

[0137] The mixed powder containing the polyimide precursor of the present invention, the fluororesin, and / or the polar crystalline fine particles may be produced by preparing the polyimide precursor aqueous dispersion of the present invention according to a conventional method, and then drying the aqueous dispersion, i.e., evaporating the water in the aqueous dispersion to obtain a solid composition containing the polyimide precursor, and then mixing the solid fluororesin and the polar crystalline fine particles with the solid composition containing the polyimide. The drying method for producing the powder containing the polyimide precursor of the present invention from the polyimide precursor aqueous dispersion of the present invention is not particularly limited, and any method may be used as long as it can evaporate the water in the polyimide aqueous dispersion of the present invention to make it into a solid state. For example, a rotary evaporator or a freeze-drying device can be used for such drying. It is preferable to use a freeze-drying device in that it can eliminate the possibility of quality deterioration due to heating.

[0138] Alternatively, the polyimide precursor-fluororesin-polar crystalline fine particle mixed powder of the present invention can be produced by directly mixing the polyimide precursor, fluororesin, and polar crystalline fine particle components in their solid state without going through the step of drying the polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion of the present invention. This production method has the advantage of being able to omit the drying step, thereby significantly reducing costs and time.

[0139] A solid preparation containing a polyimide precursor in a solid state (powder or granule) prepared as described above exists in a stable state at room temperature for at least 2 months, or at least 3 months, 4 months, 5 months, 6 months, 7 months, 8 months, 9 months, 10 months, 11 months, or 12 months or more. In this specification, the term "stable state" for a solid preparation containing a polyimide precursor means that the preparation is in a state in which it can exhibit a predetermined performance as a polyimide precursor dispersion when water is added to reconstitute the aqueous dispersion.

[0140] A solid preparation containing the polyimide precursor of the present invention in a solid state (powder or granule) can be stored at room temperature. Specifically, the preparation can be stored satisfactorily at a temperature of, for example, 15°C to 25°C, 10°C to 30°C, or 5°C to 35°C, but is not limited to this temperature range, and can also be stored in a range of up to -20°C to 45°C.

[0141] In the solid preparation containing the polyimide precursor in a solid state (powder or granules) of the present invention, it is essential that the polyimide precursor is in a solid state (powder or granules), but a fluororesin and / or a polar crystalline material can also be added in a solid state (powder or granules).

[0142] The solid preparation containing the polyimide precursor in a solid state (powder or granules) of the present invention may contain, as additional components, additives for modifying the mixed aqueous dispersion, in addition to the above-mentioned basic components.

[0143] Such additives include, for example, solvents, tackifiers, plasticizers, curing agents, crosslinking agents, diluents, fillers, thickeners, pigments, stabilizers, adhesion enhancers, flow agents, and defoamers, and any additives that are commonly used to modify the properties of the mixed aqueous dispersion and are obvious to those skilled in the art can be used. More specifically, such additives can include titanium oxide, epoxy resins, LCPs, carbon black carbon fibers, phenoxy resins, PEI (polyethylimide), phenolic resins, lignin, and aggregates (chopped pieces).

[0144] The polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion of the present invention can be reconstituted from the solid (powdered or granular) polyimide precursor prepared as described above by adding water and stirring thoroughly until a uniform dispersion is obtained. The reconstituted dispersion can be suitably used as a raw material for polyamide paints / coatings.

[0145] The coating method using the polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion of the present invention includes a step of applying the polyimide-fluororesin-polar crystalline fine particle mixed aqueous dispersion to a coating surface, and a step of heat-treating the surface at 350 to 400° C. The heat treatment is also called baking, and is a step necessary for producing the coating film or coating of the present invention, but the method of heat treatment is not particularly limited, and a typical heating device used in the field can be used.

[0146] In other words, the reconstituted polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion can be used in the same way as the conventional polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion, and the formed coating film can form a high-performance film similar to the conventional Quattron (registered trademark). EXAMPLES

[0147] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0148] (Example 1: Preparation of a mixed solid composition containing the polyimide precursor of the present invention, a fluororesin, and / or polar crystalline fine particles from a polyimide precursor-fluororesin-polar crystalline fine particles mixed aqueous dispersion) (1-1 Preparation of polyimide precursor aqueous dispersion) A conventional polyimide precursor aqueous dispersion was produced as follows: This polyimide precursor aqueous dispersion had a composition similar to that of a conventional product (Imitron PIW-20) from Nakada Coating Co., Ltd.

[0149] (1) 876.30 kg of ionized water (38.1%) was placed in a preparation tank, and while stirring, 243.80 kg of (2) MDEA (dimethyldiethanolamine) (10.6%) was added, and the temperature inside the tank was heated to 70°C. In a separate container, 680.80 kg of (3) ionized water (29.6%) (a portion of the water was left over) and 2.30 kg of (4) MDEA (0.1%) were mixed and stirred at 1000 rpm, while 460.00 kg of (5) polyimide acid (PIA) (20.0%) was added and stirred for about 30 minutes to form a uniform paste. Next, while stirring the preparation tank containing (1) and (2) at 1500 rpm, the paste of (3)-(5) was gradually added. At this time, a portion of (3) that had been left over was used to wash the paste container, and the operation was performed so that the entire amount of the paste was added. The mixture of (1)-(5) was stirred for 60 minutes until the contents were completely dissolved. Next, 23.00 kg of (6) trimethyl orthoformate (stabilizer, Tokyo Chemical Industry Co., Ltd.) (1.0), 4.60 kg of (7) KBM-603 (adhesion enhancer, Shin-Etsu Chemical Co., Ltd.) (0.2), 4.60 kg of (8) F444-10% PM (flow agent, DIC Co., Ltd.) (0.2%), and (9) D604-10% PM (antifoaming agent, Nissin Chemical Industry Co., Ltd.) were added while stirring at 500 rpm to homogenize the suspension.

[0150] The suspension thus obtained was subjected to process inspection. When the suspension was diluted to a 2.5% solution, it became transparent to the naked eye. The presence of particles was 0μ, whereas the standard was <10μ. Then, filtration was performed using Yoshino paper. The filtration speed was 39 seconds per kg.

[0151] The physical properties of the suspension after filtration were as follows: viscosity (20°C) 90±30 mPs·s, density (20°C) 1.10±0.02, solids content 20±2%, and pH 8.0±0.5.

[0152] Next, the performance of this polyimide as a paint / coating agent was measured using the suspension after filtration. A coated plate creation test was carried out using a PET substrate. The coating was carried out using a bar coater #14, and the coating was cured by hanging and baking at 120°C for 10 minutes. The solid content was measured using an aluminum petri dish, 0.1 x 100 cm 2 The evaluation was performed using the 150°C x 20 minutes method.

[0153] The results of the coating film creation test showed that the appearance of the coating film was equivalent to that of the sample.

[0154] (1-2 Preparation of polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion) Using the polyimide precursor aqueous dispersion prepared above, a polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion was prepared. The composition of this dispersion was as follows: Polyimide precursor dispersion (W-20; Nakada Coating Co., Ltd.): 30% by weight PTFE dispersion (PTFE-D; manufactured by Daikin Industries, Ltd.): 70% by weight Pink tourmaline dispersion: Prepared as a 30% dispersion of pink tourmaline (from Sri Lanka) with a particle size of 3 μm or less. Alumina sol (Al-L7; manufactured by Taki Chemical Industry Co., Ltd.): 5% by weight

[0155] The polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion was prepared as follows. 1. Pink tourmaline powder was crushed by a standard method, sieved through a 3 μm sieve to select fine particles with a particle size of 3 μm or less, and added to water to make a 5% suspension. 2. Potassium persulfate was added to pure water so that the concentration was 1% by weight, and the water was heated to 95°C to dissolve the potassium persulfate, preparing an aqueous solution of potassium persulfate. 3. A polyimide precursor dispersion, a PTFE dispersion, an alumina sol, an aqueous potassium persulfate solution, and a pink tourmaline dispersion were mixed to produce an example (a mixed aqueous dispersion of polyimide precursor-fluororesin-polar crystalline fine particles). The pH was confirmed to be 7.0 to 8.0.

[0156] (1-3 Preparation of solid (powder / granule) formulations from aqueous dispersions of polyimide precursor-fluororesin-polar crystalline particles) 100 mL of the polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion prepared as above was placed in a rotary evaporator and evaporated at 30 to 60° C. while rotating. Approximately 50 g of solid (powder / granules) was obtained, which corresponds to the solid content of the polyimide precursor-fluororesin-polar crystalline fine particle mixed aqueous dispersion (theoretical value is 51.6 g, which is the sum of polyamic acid solid content (20%×0.3×100 g=6 g), PTFE solid content 60%×0.7×100 g=42 g, and tourmaline = 3.6%×100 g=3.6 g).

[0157] (1-4 Reconstitution of aqueous dispersion from solid (powder / granule) formulation) Distilled water was added to the solid formulation obtained in (1-3) and 100 mL of aqueous dispersion was reconstituted with slow stirring. The reconstituted aqueous dispersion could be used as a paint / coating agent, just like the dispersion before it was solidified (powder / granules).

[0158] (Example 2: Preparation of solid (powder / granule) Quattron (registered trademark) (1)) In order to prepare a solid-state formulation for making a polyimide precursor-fluororesin-polar crystalline microparticle mixed aqueous dispersion, we considered preparing the formulation in a solid state from the beginning, rather than removing water from the aqueous dispersion. <Purpose> The purpose of this project is to prototype a powder type of Quattron (registered trademark), confirm the liquid properties and coating film, and determine the appropriateness of shipping samples. <Background> We would like to promote the expansion of Quattron (registered trademark) overseas. Because precipitation and trade regulations are obstacles in the liquid state, we are considering having potential overseas customers liquefy Quattron (registered trademark), and then sending them a mixed powder of PI and tourmaline (hereinafter, BT). We will prototype PI x BT powder with a composition that will result in Quattron (registered trademark), and confirm the liquid properties and coating film. <Main items used> ·PIA powder - PIA Chemical 25μm (compatible with polyamide precursors) BT-Eigado Co., Ltd., Seishin Enterprises Crushed Product (BT1-2) (for extremely small crystals) ·PTFE-D- JPEG2024108760000007.jpg961 SFN-2H Lot:2160124375 (Compatible with fluororesin) ·Amine-MDEA (Methyldiethanolamine) Water - Tap water

[0159] <Experimental Procedure> 1.Liquid formulation In this example, the objective is to develop an alternative formulation method that corresponds to the polyamide precursor described in Example 1. The composition of each agent is as shown in Table 1 below (Table 1). This time, the composition was designed to be 500 g in total when liquefied into Quattron (registered trademark).

[0160] [Table 1] The underlined parts of the recipe correspond to the amounts of PIA and BT used in solid state. First, this mixed powder was prototyped. About 70g was recovered, and 50g was taken from this to prototype a small-scale Quattron (registered trademark) (Table 2) for testing.

[0161] [Table 2]

[0162] This time, we assumed a mix that would weigh 500g when liquefied into Quattron (registered trademark). <Input procedure> 1. Add (2) to (3) 2. Heat in a 60℃ bath 3. Add the mixed powder ((1) x (4)) as is and mix for 1.5 hours using a bubbleless mixer (small). 4. Shake at room temperature for 2 hours 5. Add (5) and stir gently with a lab spoon. 6. Filter through 140 mesh Next, the liquid properties of this liquid were examined. For comparison, we used the liquid from our seventh scale-up trial run using Quattron (registered trademark) 1100. Solid content measurements were performed at 125°C for 60 minutes.

[0163] [Table 3]

[0164] Since the solid content was only 1% different from the comparison target, it was determined that the mixture itself was correct. The pH was a little high, but since PIA from PI Chemical Industry Co., Ltd. tends to have a higher pH than PIA from Nakata Coating Co., Ltd., it was determined that this was not a problem.

[0165] We also tried coating aluminum foil with a bar coater. We used 36 grit. Drying at 120℃ for 30 minutes, then baking at 380℃ for 15 minutes. Compared to the conventional product, the surface was rougher and the color was darker. More specifically, the coating film of this product was: -Poor surface slipperiness -Because the mesh used for filtration was coarse, a lot of particles remained. The color of this product is slightly browner. This product has a lot of liquid bubbles. The following points were identified as issues to be considered in the future: (1) Introduction of a filtration mechanism (customer needs a precision filtration mechanism → as a measure against particles) (2) Introducing a defoamer (to break down bubbles during coating) (3) Understanding the appropriate amount of amine for P.I. Chemical's PTA (reducing pH to the 8 range → extending liquid life with hydrolysis resistance) (4) Identifying the causes and solutions for the lack of slipperiness and color problems of the coating film It was decided.

[0166] (Example 3: Preparation of solid (powder / granule) Quattron (registered trademark) (2)) <Method> A formulation was prepared in the same manner as in Example 2, except that an antifoaming agent (D604-10% DM, manufactured by Nisshin Chemical Industry Co., Ltd.) and a flow agent (F444-10% PM, manufactured by DIC Co., Ltd.) were added at 0.2% each. <Result> Although little change was observed in the color, the slipperiness of the coating surface was observed to be comparable to that of a coating prepared using a conventional aqueous dispersion.

[0167] (Example 4: Prototype of PIA powder containing amine) <Purpose> To confirm whether or not amine-containing PIA powder can be produced. <Background> PI-W-20 (aqueous amic acid solution) is made water-soluble by adding PIA powder to water with added amine. For example, when exporting Quattron, tourmaline precipitates violently during transportation, making it difficult to handle. If a solid mixture of amine liquid and PIA powder is made, it can be shipped to the site, where it can be mixed with PTFE-D, tourmaline, and water on the spot and used as Quattron (registered trademark). The quality of the PIA powder with amine can be confirmed by the liquid properties (pH, solids, visual inspection) when it is made water-based, and the coating film properties (visual inspection, adhesion), but in this case, the liquid properties will be the evaluation item. <Main items used> ·Amine-MDEA (Dimethylethanolamine) Stock Solution PIA-PIA-25 (PIA Chemicals, 25μm, Lot unknown)

[0168] <Implementation details> [4-1] Small scale lab scale Put the PIA powder into a plastic bag, add the amine, and knead the bag with your hands to mix so that the amine is distributed throughout. This amine-containing PIA powder was prototyped with the following composition:

[0169] [Table 4]

[0170] The total amount prepared was 100g, but there was a loss and only 75.7g (☆) was recovered. A portion of the ☆ was used to make a water-based product based on the recipe below. When a prototype was made with this formulation, the actual solid content was measured to be between 19 and 22% when it was made water-based.

[0171] [Table 5] For the aqueous conversion, the mixture was stirred for 2.5 hours with a bubbleless mixer (air-driven type, air pressure 0.4 MPa), and the tap water in the mayonnaise bottle (225 mL) was heated to maintain the temperature at 60° C. After 2.5 hours, the aqueous conversion was confirmed.

[0172] The finished product was filtered through a 140 mesh filter, and the pH and solid content were measured after the liquid had cooled to room temperature. The solid content was measured by drying at 250°C for 30 minutes. As a comparison (reference), a PIW using PIA powder was also produced and tested.

[0173] [Table 6]

[0174] The amine-containing PIA prototyped in this example produced test values ​​that were almost the same as those of the control.

[0175] [4-2] Lab scale-up (Mazetaro) The same experiment was carried out using JM's own concrete mixer "Mazetaro" (electric concrete mixer Mazetaro, manufactured by Alumis Co., Ltd.) to confirm whether or not it would be possible to make the mixture water-based. The mix ratio is shown in Table 6. The important points in this trial were whether the test values ​​for the water-based liquid were plausible, and how to distribute the amine evenly across the large volume of PIA powder. A spray method was tried for adding the amine, but because the PIA powder sprayed out of the mixer, the method was changed and the amine was added in small portions into a plastic beaker.

[0176] [Table 7]

[0177] The amine was added to the PIA placed in the mixer and rotated (240 rpm) for 60 seconds. This counted as one set, and a total of six sets were performed. As the number of sets increased, it became clear that some areas had resin that formed into balls and others did not. In addition, the amine-rich resin layer tended to stick to the inner walls of the mixer. When recovering, this stuck material was also scraped off with a metal spoon. As the material was quite firmly stuck, it could not be completely recovered and some was lost. The recovered weight was 5.79 kg (yield: 89.9%).

[0178] [Table 8]

[0179] The aqueous solution was prepared based on Table 8. The test results were as follows:

[0180] [Table 9]

[0181] The pH was 0.25 higher than in Experiment 1. There was almost no difference in the solids content, and the results were as per the formula.

[0182] Next, the performance of the amine-containing PIA prepared as above as a paint / coating agent was investigated. The amine-containing PIA (part 2) prepared using Mazetaro as above was subjected to the water-based and coating procedures, and the coating film after baking was compared with that of a commercially available PIA suspension (PIW, Nakata Coating Co., Ltd., lot E22201) as a positive control. The results showed that the amine-containing PIA (part 2) of the present application had a large repelling effect and noticeable unevenness on the surface. This was thought to be the result of the amine-containing PIA (part 2) of the present invention not containing additives that reduce surface tension, and therefore the repelling effect, which is a weakness of water-based paints, being significantly reflected.

[0183] <Summary> When scaled up using a mixer, the pH and solid content are almost the same as the prototype PIW20 made from powder, and there are almost no problems with visual inspection. However, when considering the manufacturing process, the volume of PIA powder becomes huge as the scale is increased, and a method to mix the amine liquid uniformly is required. If this problem can be solved, it will be possible to make it water-based by following the formulation of this project. In actual coating films, the product in this project has strong repelling properties, so there are still issues to be addressed, such as selecting fluorine-based or silicone-based additives to increase wettability in the same way as Nakata Coating Co., Ltd. and having the customer add them.

[0184] Example 5: Storage of solid-state feed composition and reconstitution of aqueous dispersion The granular raw material composition obtained in Example 1-4 was stored at room temperature for 3 months (for example, from July to September, an average of about 28° C.), and then water was added thereto and the mixture was stirred to prepare an aqueous dispersion.

[0185] Example 6: Preparation of coatings from reconstituted aqueous dispersions The reconstituted aqueous dispersion in Example 5 was used to prepare a fluororesin coating by a conventional method.

[0186] The coating obtained from the reconstituted aqueous dispersion was able to form a coating similar to that obtained from a conventional aqueous dispersion (prepared from a solid state (powder / granules) when used).

[0187] A heat resistance test (TG-DTA test) was conducted on the coating film from the reconstituted aqueous dispersion, and it was found that even when the dispersion was reconstituted using the solid preparation for preparation at the time of use according to the present invention, it exhibited heat resistance up to about 450°C, similar to the case when the conventional aqueous dispersion was used as is.

[0188] Furthermore, even when the dispersion was reconstituted using the solid preparation for preparation immediately before use according to the present invention, it was found that the edges of the cuts were completely smooth and no peeling was observed in any of the lattice meshes, demonstrating high adhesion, just as in the case when the conventional aqueous dispersion was used as is. [Industrial Applicability]

[0189] The solid (powder / granular) polyamide precursor of the present invention can solve problems associated with Quattron (registered trademark), which is an aqueous dispersion, such as storage problems (quality deterioration over long periods of time, at high temperatures, under oxidative conditions, etc.), transport problems (need for dedicated containers, difficulty in transport due to weight, need for measures against liquid leakage, etc.), and the dangers associated with the aqueous dispersion, which in turn lead to cumbersome customs procedures during import and export. By significantly improving the inconvenience of handling the conventional Quattron (registered trademark), it is possible to expand the production of various industrial products that exhibit excellent performance such as excellent thermal conductivity, insulation, chemical resistance, heat resistance, etc., using the coating film having the excellent performance of Quattron (registered trademark), including, for example, Teflon (registered trademark) coatings for cooking utensils, nuts and bolts for insulating parts, air conditioner filters, etc., and contribute to the development of industrial society.

Claims

1. 1. A method for producing an aqueous paint / coating raw material composition, comprising: a) preparing a solid-state polyamic acid-containing composition; b) preparing a solid state polar crystalline composition; and c) mixing the solid polyamic acid obtained in step a) and the solid polar crystalline composition obtained in step b) A method comprising:

2. 2. The method of claim 1, wherein the solid-state polyamic acid-containing composition comprises 20 to 50% (w / w) of an amine compound.

3. 3. The method of claim 2, wherein the amine compound is dimethyldiethanolamine (MDEA).

4. The method according to claim 1, further comprising the step of: d) preparing a fluororesin composition and mixing it with the mixture obtained in step c).

5. The method according to claim 4, wherein the fluororesin composition is a dispersion of fluororesin fine particles made of a polymer or copolymer of a monomer selected from the group consisting of tetrafluoroethylene (PTFE), hexafluoropropylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), vinylidene fluoride, and vinyl fluoride, and the polar crystalline composition is a dispersion of pink tourmaline or black tourmaline.

6. The method of claim 1 , wherein the solid state is a powder or granule.

7. The solid-state polyamic acid-containing composition is i) processing a solid material containing polyimide into a suitable size; ii) a step of alkali treating the shredded polyimide-containing solid material, in which the solid material is dissolved in a treatment solution containing a basic substance, and the resulting solution is heated for a certain period of time to subject the polyimide in the solution to a partial hydrolysis reaction, thereby producing a polyamic acid-containing aqueous suspension in which a portion of the polyimide has been replaced with polyamic acid; iii) adding a pH adjusting liquid to the polyamic acid-containing aqueous suspension to neutralize the polyamic acid-containing aqueous suspension; and iv) subjecting the neutralized polyamic acid-containing aqueous suspension to at least one drying treatment to form polyamic acid-containing granules.

5. A method for producing the aqueous paint / coating raw material composition of claim 4, which is produced by a method comprising:

8. 8. The method for producing an aqueous raw material composition for paints / coatings according to claim 7, wherein the polyimide-containing solid material is a recycled polyimide film, the basic substance is at least one selected from sodium hydroxide and potassium hydroxide, the pH adjusting liquid is at least one selected from hydrochloric acid, sulfuric acid, and citric acid, and the drying treatment is selected from spraying, heat drying, and freeze drying.

9. The polyamic acid-containing granules have a specific gravity of 0.25 to 0.45 g / cm ３ and the average particle size is 20 to 25 μm.

10. 2. The method of claim 1, wherein the polar crystal composition is one or more fine particles selected from the group consisting of pink tourmaline and black tourmaline.

11. The method according to claim 10, wherein the polar crystalline fine particles have a particle size of 3 μm or less.

12. The method according to claim 7, wherein the weight ratio of the polyamic acid dispersion to the fluororesin composition is 45 / 55 to 15 / 85, and the polyamic acid dispersion is adjusted by adding water so that the weight ratio of the polyamic acid-containing granules to water is 1 / 99 to 50 / 50.

13. 13. The method according to claim 12, wherein the weight ratio of the total of the polyamic acid dispersion and the fluororesin composition to the polar crystalline fine particles is 100 / 20 to 100 / 40.

14. 10. The method of claim 1, further comprising mixing alumina, or potassium persulfate, or both.

15. 2. The method of claim 1, further comprising the step of mixing at least one component selected from the group consisting of titanium dioxide, epoxy resin, LCP, carbon black, carbon fiber, phenoxy resin, PEI (polyethylimide), phenolic resin, lignin, and aggregate (chopped pieces).

Images