972 results about "Polyamic acid" patented technology

The invention belongs to the technical field of gel materials, and particularly relates to aerogel powder for polyolefin modification and a preparation method and application thereof. The preparation method of the aerogel powder comprises the following steps: (1) preparing aramid nanofiber dispersion liquid; (2) preparing a polypyrrole coated aramid nanofiber dispersion liquid; (3) mixing polyamide acid and the polypyrrole coated aramid nanofiber dispersion liquid, and then carrying out partial imidization and solvent exchange to prepare hydrogel; and (4) carrying out freeze drying, thermal imidization and crushing to obtain the aerogel powder for polyolefin modification. The aerogel powder is a porous solid material formed by forming one-dimensional composite fibers from aramid nanofibers and polypyrrole and combining the one-dimensional composite fibers with polyimide resin. The aerogel powder and polyolefin resin are compounded to obtain the polyolefin resin composite material with high strength and antistatic property, and the polyolefin resin composite material can be widely applied to the fields of pipes, plates, grouting equipment parts, grouting bags and the like.

The invention discloses a preparation method and application of a water-based polyamide acid sizing agent, and belongs to the technical field of sizing agents. The method comprises the following steps: synthesizing polyamic acid in an organic solvent by adopting dianhydride and diamine in a polymerization manner, after the reaction is finished, cooling a polyamic acid solution to room temperature, transferring into a dropping funnel, dropwise adding into a solvent of which the volume is 10-25 times that of the solution, separating, completely dropwise adding, collecting a precipitate, and drying to obtain solid polyamic acid; and adding a low-grade ester or low-grade ketone solvent into the deionized water, adding the polyamide acid powder into the mixed solvent according to the solid content of 1-20wt.%, stirring at room temperature until the solid disappears, and standing for liquid separation to obtain a lower layer which is the polyamide acid water-based sizing agent. The sizing agent disclosed by the invention shows excellent dispersity and long-term stability. After sizing, polyamide acid on the surface of the carbon fiber is converted into polyimide through a thermal imidization reaction, so that the carbon fiber has high thermal stability and excellent compatibility.

The invention provides a preparation method of an h-BN / PI high-temperature-resistant anticorrosive coating, and relates to the technical field of polymer composites.The preparation method of the h-BN / PI high-temperature-resistant anticorrosive coating comprises the steps that under the protection of inert atmosphere, aromatic diamine containing impurity element five-membered rings and aromatic dianhydride containing ether bonds are taken and subjected to a polymerization reaction in a polar aprotic solvent, and the h-BN / PI high-temperature-resistant anticorrosive coating is obtained. A polyamide acid solution is obtained; performing ultrasonic-assisted liquid phase stripping on the micron-sized hexagonal boron nitride to obtain single-layer hexagonal boron nitride; adding the single-layer hexagonal boron nitride into the polyamide acid solution for multiple times, and uniformly stirring to obtain a hexagonal boron nitride / polyimide composite solution; and coating the hexagonal boron nitride / polyimide composite liquid on a to-be-coated surface, and carrying out gradient heating curing to obtain the h-BN / PI high-temperature-resistant anticorrosive coating. The h-BN / PI high-temperature-resistant anticorrosive coating based on interaction of multiple hydrogen bonds has relatively good high temperature resistance, relatively good resistance mechanical property and excellent corrosion resistance.

The invention discloses CPVC (Chlorinated Polyvinyl Chloride) modification-based high-wear-resistance antistatic plastic and a preparation method thereof, belongs to the technical field of composite CPVC preparation, and aims to solve the technical problem that the wear resistance and the antistatic property of CPVC-based plastic in the prior art need to be further improved. The high-wear-resistant antistatic plastic based on CPVC modification comprises the following raw materials in parts by weight: 80-100 parts of modified CPVC, 6-8 parts of a modified heat stabilizer and 8-16 parts of an auxiliary material, the amino group on the surface of the prepared antistatic filler participates in the ammoniation process of the prepared CPVC, a large number of amino groups hybridize the chain segment structure of the CPVC and introduce tertiary amino groups, and an ion structure is introduced into the hybridized CPVC through quaternary ammonium salinization to obtain the modified CPVC. The CPVC-based plastic is obtained by mixing, melting and extruding the CPVC-based plastic, the prepared polyamide acid-based modified heat stabilizer and auxiliary materials.

The invention relates to a fluoride-free polyimide-based film and a preparation method thereof. The method comprises the following steps: S1, preparing a polyamide acid solution; s2, fluorine-free organic silicon serving as a modifier is added into the polyamide acid solution and dispersed, a blended spinning solution is formed, and the solubility parameter difference value of the fluorine-free organic silicon and polyamide acid is 2.0 (MPa) 1 / 2 or below; s3, carrying out electrostatic spinning on the blended spinning solution to form a polyamide acid-based nanofiber layer; and S4, carrying out thermal imidization on the polyamide acid-based nanofiber layer to obtain the fluoride-free polyimide-based film. The film has a structure formed by three-dimensional cross-linking and winding of polyimide-based nanofibers, and the polyimide-based nanofibers are composed of a polyimide base material and fluorine-free organic silicon dispersed in the polyimide base material. The method does not involve fluorine-containing raw materials, and is environment-friendly and high in process compatibility. The film provided by the invention has excellent waterproofness, air permeability and mechanical properties at the same time.

The invention belongs to the technical field of aerogel, and particularly relates to high-conductivity aerogel powder as well as a preparation method and application thereof. The preparation method comprises the following steps: firstly preparing a graphene / polypyrrole nanosheet composite material with a three-dimensional structure, and then preparing the polyimide / graphene / polypyrrole ternary hybrid conductive aerogel by taking a polyamide acid solution as a precursor through a solution dipping and freeze drying process. Polyimide is used as a framework of high-conductivity aerogel powder, excellent mechanical strength and structural integrity are provided, the common brittleness problem of a pure graphene carbon material or polypyrrole conductive polymer aerogel is solved, and the three-dimensional graphene / polypyrrole nanosheet composite material has excellent elasticity and toughness and can be used for preparing a composite material with high conductivity. The polyimide aerogel prepared by the method can be dispersed in a polyimide matrix as a nano reinforcement, can effectively transfer stress and prevent crack propagation, and endows the aerogel with higher mechanical properties.

The invention relates to a preparation method of a porous polyimide low-dielectric material. The method comprises the following specific steps: preparing a polyamide acid solution with a certain solid content under an ice-water bath condition; after the solution is recovered to normal temperature, adding a certain amount of sodium alginate, and after the solution is homogenized, adding a catalyst and a dehydrating agent for chemical imidization; the method comprises the following steps: coating a substrate medium with a solution after a certain time of reaction, standing in air for a certain time, sequentially and respectively placing the substrate medium in ethanol and a hot water bath for replacement for a certain time, airing at normal temperature, and transferring to a high-temperature oven for gradient cyclization to realize complete imidization. According to the method, conditions are mild and easy to control, and the low-dielectric film material which is flat in appearance and ordered in structure is prepared only through a normal-pressure drying method.

The invention provides a polyimide multilayer composite membrane material as well as a preparation method and application thereof, and belongs to the technical field of gas separation. According to the method, through collaborative design of a functional support layer, a gradient MOF layer and an ultrathin selection layer structure, the problems of support layer pore seepage, MOF agglomeration, weak interface bonding and the like in an existing composite membrane material are solved. The preparation method comprises the following steps: firstly, carrying out electrostatic spinning on a polyamide acid glue solution, and synchronously introducing dopamine by adopting a chemical imidization method to prepare a functionalized polyimide fiber membrane containing hydroxyl and amino on the surface, so that the mechanical property of a supporting layer and the MOF anchoring capability are remarkably improved; growing MOF layers with different particle sizes on the surface of the fiber membrane by regulating and controlling the concentration gradient of ligand / metal salt and the reaction time, and passivating through a silane coupling agent after each step of growth so as to avoid heterogeneous nucleation and construct a gradient structure; after the MOF gradient layer is subjected to Ar plasma pretreatment to introduce hydroxyl, the ultrathin polyamide selection layer is formed by utilizing interfacial polymerization of fluorine-containing acyl chloride and a macrocyclic amine monomer, and the ultrathin polyamide selection layer is suitable for gas separation work.

The present application relates to the technical field of polyimides and relates to a preparation method for a high-performance polyimide and an application thereof, aiming to solve the problems in the prior art such as numerous side reactions and severe impact on transparency caused by an excessively high imidization reaction temperature during the use of a high-temperature thermal imidization method for the preparation of polyimides. The preparation method comprises: (1) preparing a polyamic acid solution; (2) adding a chemical catalyst and a polyamic acid solution to partially complete an imidization reaction; (3) adding an end group auxiliary agent, performing coating with the solution, heating, and maintaining the heat to complete the imidization reaction; and (4) carrying out high-temperature treatment to obtain a high-performance polyimide. The present application can significantly reduce numerous side reactions present in a traditional imidization reaction, eliminate an adverse effect of high-temperature imidization on the optical performance, greatly improve the mechanical properties, heat resistance, optical performance, etc. of a material, and also achieve both high heat resistance and high transparency.

The invention belongs to the technical field of lithium ion batteries, and discloses a carboxyl-containing copolyimide binder, a lithium ion battery silicon negative electrode, a lithium ion battery and a preparation method, and polyamide acid is prepared by using a carboxyl-containing diamine monomer, an amino-terminated long aliphatic chain diamine monomer and an anhydride monomer as raw materials; and carrying out chemical imidization, precipitation and washing on the polyamide acid to obtain the carboxyl-containing copolyimide binder. The prepared carboxyl-containing copolyimide binder has good solubility in a conventional electrode manufacturing solvent, and the solution system of the obtained carboxyl-containing copolyimide binder is uniform and stable. When the carboxyl-containing copolyimide binder is applied to preparation of a silicon negative electrode of a lithium ion battery, the carboxyl-containing copolyimide binder can generate dual covalent interface interaction with silicon active material particles and conductive material particles, so that the migration efficiency of lithium ions in an electrode system is remarkably improved, the transmission dynamics performance is enhanced, and the high-rate charge-discharge capacity of the battery is effectively improved.

The invention discloses a kind of preparation method of amino hyperbranched siloxane and its modified polyimide aerogel material.First, alkoxysilane X with amino active functional group, alkoxysilane Y of inactive functional group and water are carried out autocatalytic controlled hydrolysis condensation under sub-stoichiometric ratio, obtain multifunctional group (such as other active groups, alkoxyl group, amino) amino hyperbranched siloxane liquid (HPSi NH2) with controllable amino content, then using HPSi NH2 as cross-linking agent and anhydride-terminated polyamic acid solution reaction to obtain functionalized polyamic acid, which is stirred with tertiary amine and deionized water to obtain functionalized polyamic acid wet gel, which is passed through freeze drying, high temperature imidization treatment to obtain amino hyperbranched siloxane modified polyimide aerogel material. This material has excellent flexibility, resilience, heat resistance and flame retardancy, and can be applied to aerospace, communication, catalysis and filtration fields.

The invention relates to the field of polyimide materials, in particular to a positive photosensitive polyimide photoresist, a polyimide film and application of the positive photosensitive polyimide photoresist and the polyimide film. The positive photosensitive polyimide photoresist with excellent performance can be prepared by taking novel water-soluble polyamic acid ester with good dielectric property, low water absorption, heat resistance and the like as film-forming resin and combining the film-forming resin with the quinonediazide compound photosensitive component, the silane coupling agent and the organic solvent; the main film-forming component polyamic acid ester is a corresponding water-soluble polyimide precursor synthesized by using a series of simple and easily available polymeric monomers, and the realization of the water solubility is not limited to specific groups such as hydroxyl, carboxyl and the like in molecules. The photoresist has the advantages of high light sensitivity, high resolution, good thermal stability and chemical resistance, good heat and humidity resistance, good adhesion to various substrates and the like, an alkaline aqueous solution can be used as a developing solution, the loss of a film in a non-exposure area in the developing process is low due to low water absorption of the alkaline aqueous solution, and the developing time is short.

The invention discloses a wide-temperature energy storage aerogel / polymer composite material and a preparation method thereof.The preparation method comprises the steps that oxide aerogel with a three-dimensional skeleton structure is subjected to silanization treatment to obtain hydrophobic oxide aerogel, then the hydrophobic oxide aerogel is dispersed into a solvent to obtain dispersion liquid, and then the dispersion liquid is subjected to ultrasonic treatment to obtain the wide-temperature energy storage aerogel / polymer composite material. The preparation method comprises the following steps: sequentially adding a diamine monomer and an anhydride monomer into a dispersion liquid, reacting under stirring to obtain a polyamide acid precursor solution dispersed with hydrophobic oxide aerogel, carrying out film casting on the polyamide acid precursor solution to obtain a dry film, and carrying out imidization treatment on the dry film to obtain the aerogel / polymer composite material. The obtained aerogel / polymer composite material can still maintain high energy storage performance and stability even at extreme ambient temperature.

The invention discloses a bending-resistant and low-dielectric transparent polyimide film for a flexible electronic device as well as a preparation method and application of the bending-resistant and low-dielectric transparent polyimide film. The surfaces of glass beads are subjected to grafting modification treatment by adopting alkali liquor and a coupling agent; performing ultrasonic dispersion to uniformly disperse the grafted and modified glass beads in a solvent; the preparation method comprises the following steps: dissolving a fluorine-containing diamine monomer in a solvent containing graft modified glass beads under a nitrogen protection atmosphere, after the fluorine-containing diamine monomer is completely dissolved, slowly adding a fluorine-containing dianhydride monomer in batches under a continuous stirring condition, and preparing a transparent polyamide acid solution containing glass beads through a condensation polymerization reaction; and uniformly coating the polyamide acid solution containing the glass beads on a glass substrate through a blade coating machine, and then carrying out gradient heating to obtain the glass bead compounded transparent polyimide film. Fluorine atoms are introduced into molecular structures of dianhydride and diamine, and grafting modified glass beads are doped to serve as filler, so that the transparent polyimide film with bending resistance and low dielectric constant characteristics is successfully prepared.

The invention discloses a low-dielectric polyimide film material and a preparation method and application thereof, and relates to the technical field of film material preparation, and the molecular structure of a polyimide copolymer in the polyimide film material comprises structural units shown in general formulas (1) and (2), the polyimide copolymer comprises aromatic ether, fluorine atoms or fluorine-containing groups and siloxane units, at least one of C and D in the structural units contains fluorine atoms or fluorine-containing groups, and the molar ratio of the content of the copolymerization components x: y: z is (1-90%): (1-50%): (1-30%). According to the preparation method, a batch feeding synthesis mode is adopted, molecular chain growth of polyamide acid is controlled through the feeding ratio, the salt forming effect of silicon-containing diamine and polyamide acid is avoided, and high-molecular-weight polyimide is obtained. The polyimide film prepared by the method has the characteristics of low dielectric constant and dielectric loss, low water absorption, good adhesion and the like, and can be applied to the fields of high-frequency and high-speed integrated circuits and the like.

The invention discloses a high-temperature-resistant and corrosion-resistant coating for an aluminum alloy heat exchange tube and a preparation method thereof, and relates to the technical field of coating materials. The method comprises the following steps that the aluminum alloy heat exchange tube is cleaned and deoiled, then a treating agent is sprayed, composite coating slurry is sprayed to the surface of the aluminum alloy heat exchange tube after curing, and the high-temperature-resistant and corrosion-resistant coating for the aluminum alloy heat exchange tube is obtained after curing treatment. Wherein the treating agent is prepared from NS-30 silica sol, deionized water and methyltrimethoxysilane; the composite coating slurry is prepared from a polyamide acid solution, a synergist, functionalized boron nitride nanosheets, modified hexagonal boron nitride, a flatting agent and a defoaming agent. The silane film introduced into the treating agent and the synergist, the functionalized boron nitride nanosheet and the modified hexagonal boron nitride introduced into the composite coating slurry effectively improve the high temperature resistance, the corrosion resistance, the adhesive force, the thermal conductivity, the aging resistance and the toughness of the coating. Therefore, the method has a wider application prospect.

The invention relates to the technical field of vacuum bag films for aeronautical manufacturing, and discloses an eleven-layer co-extruded film for aeronautical use and a preparation process thereof, and the preparation process specifically comprises the following steps: carrying out grafting modification treatment on polyamide acid by using a monoalkenyl diepoxy composite flexible compound through a carboxyl-epoxy ring-opening reaction to prepare alkenyl functionalized processable polyimide; the preparation method comprises the following steps: carrying out modification treatment on nylon 6 resin by using 3-mercaptopropionic acid through an amino-carboxyl condensation reaction to prepare mercapto functionalized nylon; under the hot melting condition, alkenyl functionalized processable polyimide and sulfydryl functionalized nylon are induced to be subjected to reactive compounding through a free radical initiator, PA-PI alloy master batch is prepared, the master batch serves as a functional modification component of copolymerized polyamide 6 / 66 resin, an eleven-layer co-extrusion film is prepared through an eleven-layer co-extrusion blow molding process, and the eleven-layer co-extrusion film is used as a functional modification component of the copolymerized polyamide 6 / 66 resin. The film product has excellent comprehensive performance and can be used as a high-temperature-resistant vacuum bag film for curing aviation composite materials.

The invention belongs to the technical field of aerogel, and particularly relates to polyimide aerogel for 3D printing as well as a preparation method and application of the polyimide aerogel. According to the preparation method disclosed by the invention, the polyaniline with a curved surface structure is prepared by taking ice micro powder as a synthesis template of an aniline monomer, and the polyaniline / polyimide composite aerogel is prepared by adopting a polyamide acid in-situ compounding method. The polyaniline with the curved surface structure is a three-dimensional conductive unit, and when the polyaniline is dispersed in a polyimide matrix, the curved surface structures can be in contact with one another, so that an efficient three-dimensional conductive network is constructed in the composite material. The curved surface structure has a relatively large specific surface area, so that a relatively large contact area is formed between polyaniline and a polyimide matrix, stress is favorably transferred from the matrix to a filler, the polyaniline with the curved surface structure is favorably prevented from being agglomerated in the matrix, the polyaniline is more uniformly distributed, and the flexibility of the polyimide aerogel is improved.

This invention relates to a method for synthesizing iron-cobalt alloy-doped carbon nanofibers for electrocatalysis using zinc oxide etching, belonging to the technical field of electrode materials and catalysts. The preparation method includes the following steps: 1) mixing DMF (dimethylformamide), PMDA (pyromellitic dianhydride), and ODA (4,4-diaminodiphenyl ether) in a certain proportion to prepare a PAA (polyamic acid) spinning solution; 2) preparing PAA nanofibers from the PAA spinning solution using an electrostatic melt-blowing device; 3) imidizing the PAA nanofibers using a programmed temperature rise method to obtain PI nanofibers; 4) impregnating the PI nanofibers in a salt solution; 5) carbonizing the impregnated PI nanofibers with a large number of metal ions on their surface in an inert atmosphere using a certain temperature rise program to obtain iron-cobalt alloy-doped carbon nanofibers. The iron-cobalt alloy-doped carbon nanofibers prepared by this method exhibit excellent performance as an ORR / OER bifunctional electrocatalyst and have wide applications.

Provided are: a liquid crystal aligning agent which contains two or more polyamic acids and in which deterioration in liquid crystal aligning properties when stored at room temperature is suppressed; a liquid crystal alignment film obtained from the liquid crystal aligning agent; and a liquid crystal display element. The liquid crystal aligning agent is characterized by containing the following polymer (A) and polymer (B). Polymer (A): a polyamic acid (A) having a structural unit derived from a tetracarboxylic acid derivative and a structural unit derived from a diamine, the polyamic acid containing, as the structural unit derived from the tetracarboxylic acid derivative, a structural unit (a-1Ta) represented by formula (1Ta), and containing, as the structural unit derived from the diamine, a structural unit (a-1Da) represented by formula (1Da), at least a part of the terminal of the polyamic acid (A) contains a non-amino group, the non-amino group is a functional group represented by structural formula (E), and the presence rate of the terminal amino group in the polyamic acid (A) is 60% or less based on the total terminal of the polyamic acid (A). Polymer (B): a polyamic acid (B) having a structural unit derived from a tetracarboxylic acid derivative and a structural unit derived from a diamine, the polyamic acid including a structural unit (b-1Tb) represented by formula (1Tb) as the structural unit derived from the tetracarboxylic acid derivative, and including a structural unit (b-1Db) represented by formula (1Db) as the structural unit derived from the diamine. (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification)

The invention relates to the technical field of polyimide fibers, in particular to a method for preparing polyimide fibers of different color systems based on in-situ coloring, which comprises the following steps: carrying out condensation polymerization on perylene tetracarboxylic dianhydride compounds or perylene diimide, diamine monomers and dianhydride monomers to obtain a polyamide acid solution; adding acetic anhydride and pyridine into the polyamide acid solution for chemical ring-closure reaction to obtain a polyimide solution; and carrying out wet spinning on the obtained polyimide solution to obtain the colored polyimide fiber. The method for preparing the polyimide fibers of different color systems based on in-situ coloring is simple in process and environmentally friendly, and the prepared polyimide fibers of different color systems are high in color fastness and excellent in mechanical property.

The invention discloses warm-keeping polyimide aerogel and a preparation method thereof, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: 1, synthesizing a polyamide acid solution; 2, adding amino-containing organic silicon into the polyamide acid solution, mixing, and defoaming to form a spinning solution; step 3, preparing a nanofiber membrane by electrostatic spinning of the spinning solution; 4, crushing the nanofiber membrane, dispersing the crushed nanofiber membrane in a solvent, standing for 24-48 hours, and freeze-drying to obtain aerogel; and step 5, carrying out stepped heating thermal imidization treatment to obtain the polyimide aerogel. Amino-containing organic silicon is used as a cross-linking agent of polyamide acid, chemical connection is added for a three-dimensional network structure of the gel, and the structural stability of the aerogel is improved. In the thermal imidization process, organic silicon generates a silicon oxide and Si-O-Si network through staged pyrolysis, the silicon oxide exists in fiber gaps and forms an organic-inorganic hybrid interface with PI fibers, and the structural stability is further improved.

The invention belongs to the technical field of carbon fiber composite materials, and particularly relates to a carbon fiber reinforced composite material for an aerospace low-temperature storage tank and a preparation method of the carbon fiber reinforced composite material. The preparation method of the carbon fiber reinforced composite material for the aerospace low-temperature storage tank comprises the following steps: (1) preparing a polyamide acid prepolymer solution; (2) adding the polyamide acid prepolymer solution, a phosphorus-containing flame-retardant monomer and nano nitrile rubber into a solvent for reaction to prepare a sizing agent; (3) carbon fibers are soaked in the sizing agent, taken out and dried, and sized carbon fibers are obtained; and (4) mixing nano nitrile rubber with a resin matrix, and then carrying out prepolymerization and thermal imidization curing molding on the mixture and the sized carbon fibers to obtain the carbon fiber composite material. The carbon fiber reinforced composite material obtained by the invention not only has excellent liquid oxygen compatibility, but also can maintain excellent leakage resistance and mechanical properties in an extremely high and low temperature cycle environment, and provides technical support for application of aerospace low-temperature storage tanks.

The invention discloses a binder and a preparation method thereof, a negative pole piece and a battery, and belongs to the technical field of batteries. The binder provided by the invention is a copolymer of linear polyamide acid and a diamino-containing aromatic compound; wherein the linear polyamide acid is a copolymer of a dianhydride monomer and a diamine monomer. The binder can alleviate the problem of volume expansion of the silicon-carbon negative electrode so as to alleviate the problem of capacity fading, and also can alleviate the capacity deterioration caused by the falling of active substances in the circulation process of the pole piece; and the conductivity of the pole piece is improved to a certain extent, and the dynamic performance of the battery is facilitated.

The invention discloses a polyimide aerogel fiber as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: 1, synthesizing a polyamide acid solution; 2, adding acrylic acid, polyethylene glycol, a photoinitiator and a cationic surfactant into the polyamide acid solution, and mixing to form a spinning solution; step 3, carrying out wet spinning on the spinning solution, and then entering a coagulating bath to form initial gel fibers; step 4, performing ultraviolet light curing on the initial gel fibers to form gel fibers; and 5, carrying out chemical imidization treatment on the gel fiber, then carrying out stretching treatment, and carrying out supercritical CO2 drying after solvent replacement so as to obtain the polyimide aerogel fiber. Under the synergistic effect of multiple components of the spinning solution, the polyimide aerogel fiber is endowed with excellent mechanical properties and high porosity in cooperation with gelation and ultraviolet curing in a coagulating bath, and the polyimide aerogel fiber can be applied to preparation of heat insulation materials.

To provide polyimide which is excellent in dimensional accuracy at high temperature while securing transparency, a method for producing a polyimide film, and a method for manufacturing a metal-clad laminate.SOLUTION: When a polyimide film is obtained by preparing a mixed solution containing a tetracarboxylic acid anhydride component, a diamine component, and an organic solvent, reacting the mixture and obtaining a solution of a polyamide acid, coating the solution onto a base material, drying the solution and obtaining a resin film, heat treating the resin film and imidizing the resin film, when the polyimide film is obtained by using a solvent containing a predetermined aprotic polar solvent and a predetermined amount of water as the organic solvent contained in the mixed solution, total light transmittance is 85% or more, polyimide having a thermal decomposition temperature (Td0.5) showing decrease in a weight of 0.5% of 460°C or higher is obtained.SELECTED DRAWING: None

The invention belongs to the technical field of liquid crystal alignment agents, and particularly relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element. The liquid crystal alignment agent comprises polyamic acid, a main chain of the liquid crystal alignment agent contains short side chain diamine and carbonate bonds, the short side chain diamine can slow down direct collision between film surfaces, carbonyl on a short side chain enhances absorption of ultraviolet light, and the compressive strength of a liquid crystal alignment film and the cracking alignment performance of the liquid crystal alignment film are improved; the carbonic ester bond can improve the voltage holding rate thermal stability of the liquid crystal alignment film and can improve the anchoring force of the liquid crystal alignment film and liquid crystals, the liquid crystal alignment agent with high compressive strength, voltage holding rate, high thermal stability and low linear polarization ultraviolet exposure is finally obtained, the stability of the high voltage holding rate improves the residual image of a display device, and the display effect is improved. And due to high compressive strength, the undesirable phenomenon of ZARA of the liquid crystal display device can be reduced.

Provided is a resin composition comprising a resin and a polymerization initiator, wherein the resin is a polyamic acid ester having an imidization rate of 3-45% and an absorbance of 0.62 or less at a wavelength of 365 nm in a 0.050 mass % solution. Also provided are a cured product, a laminate, a method for producing a cured product, a method for producing a laminate, a method for producing a semiconductor device, a semiconductor device, and a method for producing a polyamic acid ester.

The application relates to the technical field of aerogel fiber preparation, and discloses a polyimide aerogel fiber and a preparation method and application thereof. The preparation method comprises the following steps: preparing a polyamide acid precursor spinning solution; spinning the polyamide acid precursor spinning solution through a wet spinning method, winding and standing in a coagulation bath to obtain a polyimide wet gel fiber; and performing solvent replacement on the polyimide wet gel fiber and rapidly drying the polyimide wet gel fiber under normal pressure to obtain a polyimide aerogel fiber. The preparation method is simple, avoids the use of a lengthy drying process and expensive drying equipment, and successfully realizes continuous molding preparation, and has a good large-scale preparation prospect. The aerogel fiber prepared by the application has excellent tensile strength, which can reach 20.5 MPa; and has low density (0.34-0.53 g.cm ‑3 -3), high porosity (63-76%) and excellent heat insulation performance, and the thermal conductivity can be as low as 36.9 W.m ‑1 -1.K ‑1 -1; and has good heat preservation effect in various complex occasions.

The invention provides a black insulating polyimide material and a preparation method thereof, and particularly provides a polyamide acid solution which comprises a diamine monomer, a dianhydride monomer and a simple substance phosphorus-containing mixture, and the simple substance phosphorus-containing mixture is a mixture obtained by ball-milling simple substance phosphorus and boron nitride or porous silicon and a solvent. The black insulating polyimide material can be prepared from the polyamide acid solution, the influence of a carbon-based material on the insulating property of the polyimide material is avoided due to the adoption of the mixture containing the elemental phosphorus, and the elemental phosphorus material does not need to be added with a plasticizer and other materials. More importantly, the simple substance phosphorus and the boron nitride or the porous silicon can enable the polyimide to be black, meanwhile, the insulating property of the polyimide is improved, the heat-conducting property is improved, and the comprehensive performance of the black polyimide material is remarkably improved.