Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a high heat-resistant insulating film for an oil-immersed transformer, which has excellent heat resistance, strong voltage breakdown resistance and longer service life.
In order to achieve the above purpose, the technical scheme of the invention is summarized as follows:
a high heat-resistant insulating film for an oil-immersed transformer is provided with a first insulating coating, a reinforcing layer, a first adhesive layer, a base material layer, a fiber layer, a second adhesive layer and a second insulating coating from top to bottom in sequence;
the first insulating coating and the second insulating coating respectively comprise the following raw materials in parts by weight:
the plasma-treated polyimide resin is added in the insulating layer, and due to the introduction of polar groups and the generation of a compact cross-linking layer, the plasma-treated polyimide resin maintains the excellent high-temperature resistance of the polyimide and increases the breakdown field strength of the material, thereby improving the high-temperature resistance and the electric breakdown resistance of the insulating film. The inorganic filler increases the compatibility and the binding force of inorganic molecules and organic molecules, promotes the dispersibility of the film, improves the strength of the film, and the polybenzoxazole resin has good insulating property, high temperature resistance, high strength, high modulus, excellent electrical insulating property and mechanical property, and the polyethylene terephthalate has excellent electrical insulating property and dimensional stability, and enhances the insulating property of the insulating layer while giving consideration to the excellent properties of all the components.
Preferably, the insulating resin comprises one or more of polyetherimide resin, polysulfone resin, polybenzimidazole resin and polyphenylene sulfide resin.
Preferably, the emulsion paint also comprises 1-2 parts of emulsified polyethylene wax.
Preferably, the boron nitride powder further comprises 1-3 parts of boron nitride.
Preferably, the polyethylene composition also comprises 1-3 parts of low-density polyethylene.
Preferably, among them, the low density polyethylene has a density of 0.92 to 0.94g/cm3。
The low-density polyethylene is a non-polar thermoplastic resin with high crystallinity, has good heat resistance and cold resistance, and has high chemical stability;
optionally, the inorganic filler is modified nano silica.
Preferably, the preparation method of the modified nano-silica comprises the following steps: preparing the nano silicon dioxide into suspension with a certain concentration by using deionized water, dispersing the suspension in an emulsifying machine at the rotating speed of 4500-.
Preferably, the mass ratio of the silane coupling agent to the absolute ethyl alcohol is 10-15: 1.
preferably, the plasma comprises an oxygen plasma or a fluorine plasma, among others.
Preferably, the first adhesive layer and the second adhesive layer are polyamide films, the base material layer is an epoxy resin layer, and the fiber layer is a glass fiber layer.
The invention at least comprises the following beneficial effects: (1) the insulating layer prepared by the invention is added with the polyimide resin treated by the plasma, and the plasma treated polyimide resin can increase the breakdown field strength of the material while keeping the excellent high temperature resistance of the polyimide due to the introduction of polar groups and the generation of a compact cross-linking layer, thereby improving the high temperature resistance and the electric breakdown resistance of the insulating film; (2) after the nano silicon dioxide is modified by the silane coupling agent, the compatibility and the bonding force of inorganic molecules and organic molecules are increased, the dispersibility of the silicon dioxide in the film is promoted, and the strength of the film is further improved; (3) the insulating film prepared by the invention has the advantages of excellent high-temperature resistance, excellent insulating property, large peeling strength of the film, simple preparation method, low manufacturing cost and suitability for large-scale popularization.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Detailed Description
The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.
It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.
Example 1
The high-heat-resistance insulating film for the oil-immersed transformer is sequentially provided with a first insulating coating, a reinforcing layer, a first adhesive layer, a base material layer, a fiber layer, a second adhesive layer and a second insulating coating from top to bottom;
the first adhesive layer and the second adhesive layer are polyamide films, the base material layer is an epoxy resin layer, and the fiber layer is a glass fiber layer.
The first insulating coating and the second insulating coating respectively comprise the following raw materials in parts by weight:
100 parts of insulating resin;
20-24 parts of polybenzoxazole resin;
16-19 parts of polyimide resin subjected to plasma treatment;
3-8 parts of polyethylene glycol terephthalate;
2-4 parts of inorganic filler.
Wherein the insulating resin is polyetherimide resin, and the density of low density polyethylene is 0.92-0.94g/cm3The inorganic filler is modified nano silicon dioxide.
The preparation method of the modified nano silicon dioxide comprises the following steps: preparing the nano silicon dioxide into suspension with a certain concentration by using deionized water, dispersing the suspension in an emulsifying machine at the rotating speed of 4500-.
Wherein the mass ratio of the silane coupling agent to the absolute ethyl alcohol is 10-15: 1.
wherein the plasma comprises oxygen plasma or fluorine plasma.
Example 2
The high-heat-resistance insulating film for the oil-immersed transformer is sequentially provided with a first insulating coating, a reinforcing layer, a first adhesive layer, a base material layer, a fiber layer, a second adhesive layer and a second insulating coating from top to bottom;
the first adhesive layer and the second adhesive layer are polyamide films, the base material layer is an epoxy resin layer, and the fiber layer is a glass fiber layer.
The first insulating coating and the second insulating coating respectively comprise the following raw materials in parts by weight:
wherein the insulating resin is polyetherimide resin, and the density of low density polyethylene is 0.92-0.94g/cm3The inorganic filler is modified nano silicon dioxide.
The preparation method of the modified nano silicon dioxide comprises the following steps: preparing the nano silicon dioxide into suspension with a certain concentration by using deionized water, dispersing the suspension in an emulsifying machine at the rotating speed of 4500-.
Wherein the mass ratio of the silane coupling agent to the absolute ethyl alcohol is 10-15: 1.
preferably, the plasma comprises an oxygen plasma or a fluorine plasma, among others.
Example 3
The high-heat-resistance insulating film for the oil-immersed transformer is sequentially provided with a first insulating coating, a reinforcing layer, a first adhesive layer, a base material layer, a fiber layer, a second adhesive layer and a second insulating coating from top to bottom;
the first adhesive layer and the second adhesive layer are polyamide films, the base material layer is an epoxy resin layer, and the fiber layer is a glass fiber layer.
The first insulating coating and the second insulating coating respectively comprise the following raw materials in parts by weight:
the insulating resin is polyetherimide resin, wherein the density of low density polyethylene is 0.92-0.94g/cm3The inorganic filler is modified nano silicon dioxide.
The preparation method of the modified nano silicon dioxide comprises the following steps: preparing the nano silicon dioxide into suspension with a certain concentration by using deionized water, dispersing the suspension in an emulsifying machine at the rotating speed of 4500-.
Wherein the mass ratio of the silane coupling agent to the absolute ethyl alcohol is 10-15: 1.
preferably, the plasma comprises an oxygen plasma or a fluorine plasma, among others.
Example 4
The high-heat-resistance insulating film for the oil-immersed transformer is sequentially provided with a first insulating coating, a reinforcing layer, a first adhesive layer, a base material layer, a fiber layer, a second adhesive layer and a second insulating coating from top to bottom;
the first adhesive layer and the second adhesive layer are polyamide films, the base material layer is an epoxy resin layer, and the fiber layer is a glass fiber layer.
The first insulating coating and the second insulating coating respectively comprise the following raw materials in parts by weight:
wherein the insulating resin is polybenzimidazole resin, and the density of the low-density polyethylene is 0.92-0.94g/cm3The inorganic filler is modified nano silicon dioxide.
The preparation method of the modified nano silicon dioxide comprises the following steps: preparing the nano silicon dioxide into suspension with a certain concentration by using deionized water, dispersing the suspension in an emulsifying machine at the rotating speed of 4500-.
Wherein the mass ratio of the silane coupling agent to the absolute ethyl alcohol is 10-15: 1.
preferably, the plasma comprises an oxygen plasma or a fluorine plasma, among others.
To illustrate the effects of the present invention, the inventors provide comparative experiments as follows:
comparative example 1
The modified silica was not added, the remaining parameters were exactly the same as in example 2, and the process was also exactly the same.
Comparative example 2
The plasma-treated polyimide resin was not added, and the remaining parameters were exactly the same as in example 3, and the process was also exactly the same.
Comparative example 3
The plasma-treated polyimide resin was changed to a polyimide resin, and the remaining parameters were exactly the same as in example 3, and the process was also exactly the same.
The results of the performance tests of examples 1-4 and comparative examples 1-3 are shown in the following table:
compared with the comparative example 1, the tensile strength of the nano-silica is increased from 81N/10mm to 98N/10mm compared with the comparative example 1, which shows that after the nano-silica is modified by the silane coupling agent, the silane coupling agent can enable the bonding interface of the polymer/silica to become chemical bond bonding, the reinforcing performance of the silica is obviously improved, and organic groups in the silane coupling agent and active hydroxyl groups on the surface of the silica are condensed to form siloxane bonds, so that the compatibility and the bonding force of inorganic molecules and organic molecules are increased, the Mooney viscosity and the rolling resistance of materials are reduced, the dispersibility of the silica in a film is promoted, and the wear resistance and the strength of the film are further improved.
Compared with the comparative example 2, the resistivity, the endurance temperature and the breakdown voltage of the example 3 are respectively from 339 ℃ to 11.3x1012Omega m rises to 379 deg.C, 14.9x1012Omega m, the polyimide resin has excellent high temperature resistance which can reach more than 400 ℃, and the polyimide also has good dielectric property and corona resistance, so the addition of the polyimide resin obviously improves the insulativity and the high temperature resistance of the material.
Compared with the comparative example 3, the breakdown voltage of the polyimide is increased from 9kV to 13kV compared with the comparative example 3, when the oxygen plasma is used for treating the surface of the polyimide, high-energy electrons can break chemical bonds at the surface of the material, the broken chemical bonds are crosslinked on the surface of the material to form a crosslinked layer, the dielectric constant of the material is correspondingly increased due to the increase of the crosslinked layer, a dense crosslinked layer with a large dielectric constant is formed on the surface of the polyimide, the intervention of charges is prevented, and the breakdown field strength of the polyimide is improved.
Therefore, the modified silicon dioxide and the polyimide resin subjected to plasma surface treatment have the beneficial effects of improving the high-temperature resistance, the electric breakdown performance and the mechanical property of the insulating film.
While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the embodiments, which are fully applicable in all kinds of fields of application of the invention, and further modifications may readily be effected by those skilled in the art, so that the invention is not limited to the specific details without departing from the general concept defined by the claims and the scope of equivalents.