410 results about "Dielectric loss factor" patented technology

The invention relates to a halogen-less high frequency resin composition, and a prepreg and a laminate manufactured by using the same. The halogen-less high frequency resin composition comprises the following components based on weight part of the organic solids: (A) 10 to 50 parts of styrene-maleic anhydride oligomer; (B) 10 to 50 parts of at least one compound containing dihydro-benzoxazine ring; (C) 10 to 50 parts of at least one polyepoxide; and (D) 5 to 30 parts of at least one phosphorus-containing flame retardant. The prepreg and the laminate manufactured by using the halogen-less highfrequency resin composition has low dielectric constant, low dielectric loss factor, high glass transition temperature, good heat resistance, low water absorbance, and simple and convenient technological operation.

The invention provides a GPS clock signal-based high voltage capacitive equipment insulation online monitoring system, including an on-site monitoring unit comprising a CPU, a wireless communication module which is 2.4GHz wireless communication module, a GPS clock receiving module, and a on-site monitoring current unit and a on-site monitoring voltage unit installed on the same bus line, and a station terminal control computer. An insulation online monitoring method includes that: the station terminal control computer sends synchronous remotely collection order to each on-site monitoring unit via 2.4GHz wireless network; each on-site monitoring unit receives GPS clock signal and realizes synchronous remotely collection of each on-site monitoring unit on the booking time, comparing the uploaded information, calculates equivalent capacitor, end screen current and dielectric loss factor of high voltage capacitive equipment after the each on-site monitoring unit obtains end screen current signal with clock signal or sequence number and PT secondary side voltage signal.

A magnetic toner having magnetic toner particles containing at least a binder resin and a magnetic material, wherein, in the test of dissolution level of the magnetic material, the dissolution percentages S3 (% by mass), S15 (% by mass) and S30 (% by mass), and the dissolution level proportion Sc satisfy the following expressions: 0.5≦S3≦10, 40≦S15≦80, 1.2≦Sc[=(S15−S3) / (S30−S15)]≦10; and the magnetic toner has a dielectric loss factor (tan δ) at 25° C. and at a frequency 1.0×104 Hz, within the range of from 2.0×10−3 or more to 1.5×10−2 or less.

The invention discloses a method for evaluating ageing state of paper oil insulation. The method is characterized by comprising the following steps of: 1, measuring a relative dielectric constant and a dielectric loss factor of a paper oil insulation test product by adopting a frequency domain dielectric spectroscopy method; 2, establishing a composite exponential function relational expression of the relative dielectric constant and insulation paper polymerization of the paper oil insulation test product, and a composite exponential function relational expression of the dielectric loss factor and the insulation paper polymerization of the paper oil insulation test product; and 3, evaluating the ageing state of a paper oil insulation system by using the relational expressions. A device provided by the invention is simple in structure, is easily implemented, and is greatly improved in accuracy.

The present invention discloses a halogen-free resin composition and a method for manufacturing a prepreg and a laminated board by using the halogen-free resin composition. The halogen-free resin composition is prepared by dispersing the following components in an organic solvent, wherein the components comprise, by weight, 10-100 parts of a halogen-free epoxy resin, 10-80 parts of cyanate, 10-70 parts of an anhydride curing agent, 10-100 parts of a benzoxazine resin, 0.01-1.0 part of a curing accelerator, 1-15 parts of a toughening agent, 0-50 parts of a fire retardation agent, and 0-100 parts of an inorganic filler, and the solid content of the halogen-free resin composition is 30-70 wt%. The prepared prepreg and the copper foil-clad laminated board have characteristics of good heat resistance, high glass-transition temperature, low water absorption rate, excellent fire retardation, low dielectric constant and low dielectric loss factor.

The invention relates to a glass fiber with a low dielectric constant for a high frequency high-density circuit board, which is characterized in that: the glass fiber comprises the following components in percentage by weight: 50 to 60 percent of SiO2, 12 to 18 percent of Al2O3, 0 to 1.8 percent of CaO, 0.5 to 3.2 percent of MgO, 0.5 to 3.2 percent of ZnO, 21 to 27 percent of B2O3, 0 to 0.25 percent of Li2O, 0 to 0.25 percent of Na2O, 0.4 to 4 percent of TiO2, 0.5 to 3 percent of CaF2, and 0.2 to 0.6 percent of CeO2. The glass fiber disclosed by the invention has the advantages of excellent water resistance, excellent adhesion with the resin and easy follow-up processing. At room temperature, when the frequency is 1MHz, the dielectric constant is between 4.2 and 4.6 and the dielectric loss factor is between 10*10<-4> and 12*10<-4>. The glass fiber is particularly suitable to be used as a reinforcing material of the high frequency high-density multilayer interconnection printed circuit board.

The invention discloses a large-scale generator stator winding major insulation aging state test method based on frequency domain spectroscopy. The method includes the steps: making a generator stop running and be reliably disconnected from a circuit, and cooling the generator to an ambient temperature; testing wiring: connecting a stator winding of the generator with a high-voltage end of a test cable of a dielectric spectrum tester, and connecting a grounding end of a housing of a generator with a grounding end of the test cable of the dielectric spectrum tester; setting a parameter and starting a test; testing a frequency characteristic curve [epsilon]-f of a major insulation complex dielectric constant of the stator winding of the generator, and obtaining the dielectric loss factor increment [delta]tan[delta]N of the current major insulation through calculation by a formula; and evaluating the aging state of the major insulation of the stator winding of the generator according to the obtained dielectric loss factor increment [delta]tan[delta]N. The method is a non-destructive test method, has simple test principles, enables convenient wiring, can accurately determine the dielectric loss factor increment [delta]tan[delta]N of the stator winding of the generator, and thus can effectively evaluate the aging state of the generator.

Curable functionalized imide-linked polyimides compounds have been synthesized that have been found to possess very low dielectric constant and extremely low dissipation factor. These compounds also have a range of high to low modulus, extremely low moisture uptake and are very thermally stable. The combination of these materials in formulation along with functionalized polyethylene, polypropylene, polybutadiens have been found to be ideal for forming films and coatings for the microelectronic applications, multiplayer capacitors and interconnects, and high power cables and wire coatings. The addition of perfluorinated hydrocarbons, and POSS nanoparticles to the formulations have decreased the dielectric constant and dielectric dissipation factor further, and have also improved the flammability of the compositions.

The invention discloses a halogen-free resin composition, a prepreg prepared from the halogen-free resin composition and a laminated board prepared from the halogen-free resin composition and used for a printed circuit. The halogen-free resin composition comprises alkylphenol epoxy resin, benzoxazine resin, an alkylphenol aldehyde curing agent and a phosphorus-contained flame retardant. The molecular structure of alkylphenol epoxy resin adopted in the halogen-free resin composition contains more branched alkyls, so that the halogen-free resin composition is relatively high in glass transition temperature, low in water absorption rate, favorable in heat resistance and excellent in dielectric performance; benzoxazine resin is mixed, so that the dielectric constant, dielectric loss value and water absorption rate of a solid can be further reduced; alkylphenol aldehyde is used as a curing agent, so that the advantages of excellent dielectric performance and low water absorption rate generated by more alkyls in the structure are sufficiently exerted. The prepreg prepared from the halogen-free resin composition and the laminated board prepared from the halogen-free resin composition and used for the printed circuit have the advantages of low dielectric constant, low dielectric loss factor, low water absorption rate, high size stability, high heat resistance, and favorable flame retardance, processability and chemical resistance.

The invention discloses a preparation method of PTFE (Polytetrafluoroethylene) copper clad laminate. The method comprises the following steps: 1, uniformly mixing raw material components of ceramic powder, silane coupling agents, deionized water and PTFE emulsion to form a PTFE glue solution; 2, soaking glass fiber cloth in the PTFE glue solution at a constant speed, and drying to obtain pretreated cloth; 3, superimposing the obtained pretreated cloth and a fluorine resin membrane into a raw substrate with specified thickness, covering the two sides of the raw substrate with copper foil, thenperforming sintering, maintaining pressure and then cooling to room temperature to prepare the PTFE copper clad laminate. The preparation method disclosed by the invention is simple, easy to operate,good in filler dispersion effect, uniform in mixing and good in product size stability. Through reasonable proportion, the prepared PTFE copper clad laminate has different dielectric constants within2.6-8.6 MHz; the dielectric loss factor is smaller than or equal to 0.003; the peeling strength is greater than or equal to 2.2 kN / m, and the comprehensive property meets use requirements and industrialized mass production requirements.

The invention relates to a thermosetting resin composition, a prepreg prepared from the composition, and a laminated board prepared from the composition and used for a printed circuit board. The thermosetting resin composition comprises phosphorus-containing low molecular weight polyphenyl ether resin, epoxy resin, cyanate resin and an accelerator. The prepreg prepared from the resin composition comprises a base material and the thermosetting resin composition which is impregnated and dried and attached to the base material. The laminated board prepared from the resin composition and used for the printed circuit board comprises a plurality of superposed prepregs and metal foils laminated on one side or two sides of the superposed prepregs, wherein each prepreg comprises the base material and the thermosetting resin composition which is impregnated and dried and attached to the base material. The thermosetting resin composition has low dielectric constant and dielectric loss factor and high heat resistance, glass transition temperature, flame retardance and the like; and the laminated board prepared from the composition and used for the printed circuit board has high metal foil peeling strength, heat resistance and dielectric property and is suitable for a high-frequency high-speed electronic circuit board.

A device for producing high power microwave plasmas. The device comprises at least one microwave feed that is surrounded by at least one dielectric tube. A dielectric fluid flows through the space between the microwave feed and the outer dielectric tube. The dielectric fluid has a small dielectric loss factor tan δ in the region of between 10−2 to 10−7. A fluid cools at least the outer dielectric tube.

The invention relates to a thermosetting resin composition and a prepreg and a laminate for printed circuits thereby. The thermosetting resin composition comprises at least an epoxy resin with a component being the structural formula (I) and a curing agent. The molecular structure of the epoxy resin composition of the invention contains the low-polarity styrene structure, therefore, the dielectricproperty of the resin is optimized. The dielectric constant and the dielectric loss angle tangent are reduced compared with those of the common epoxy resins. The prepreg obtained by coating the resincomposition on the substrates and the laminate manufactured by laminating the prepreg simultaneously have the characteristics of low dielectric constant, low dielectric dissipation factors, good heatresistance, good dip soldering resistance, good moisture resistance, good humidity resistance and good cohesiveness with copper foils. The resin composition of the invention can be also used for manufacturing the resin sheets, resin composition copper foils, the laminate and the printed circuit boards. R is (a), and n and m are natural numbers.

Provided is a magnetic toner capable of preventing electrostatic offset while attaining a high image quality by a high speed machine. The magnetic toner comprises magnetic toner particles, each of which contains a binder resin and a magnetic material, and a fine inorganic powder, in which the binder resin contains a polyester unit, and the magnetic toner has a dielectric loss factor at 40° C. and 100 kHz of 0.40 pF / m or more but 1.00 pF / m or less and a dielectric loss factor at 150° C. and 100 kHz of 0.50 pF / m or more but 4.00 pF / m or less.

The invention relates to a method for assessing an insulation state of oil paper based on characteristic quantity of frequency domain dielectric spectroscopy. The method comprises following steps: utilizing a linear medium response equivalent circuit to simulate polarization characteristics of the insulation state of oil paper for a transformer and setting up the relationship between linear medium response equivalent circuit parameters, frequency-domain characterization complex capacitance and dielectric loss factors; then, utilizing complex capacitances with high frequency bands and a parametric equivalent circuit model for dielectric loss characteristic quantity and finally, integrating dielectric loss curves with low frequency bands at prediction sections, wherein the range of frequency bands in a dielectric loss frequency domain is equally divided into n frequency points (n larger than or equal to 1), n frequency points correspond to n dielectric loss integral value and n frequencies and corresponding dielectric loss integral value are fitted to a function curve. The method for assessing an insulation state of oil paper based on characteristic quantity of frequency domain dielectric spectroscopy has following beneficial effects: in order to obtain much more insulation information carried by dielectric loss factors within the limited measurement frequency domain, integrals of dielectric loss factors are utilized in the predicted low-frequency section as characteristic parameters for assessment of insulation state; and dielectric loss integral value within the low-frequency stage obtained by calculations is utilized for determining the insulation aging state of oil paper.

Provided is a magnetic toner capable of providing a stable image by suppressing sleeve contamination even under a high-temperature and high-humidity environment and under a normal-temperature and low-humidity environment and further suppressing large-particle fogging caused after the toner is left alone for a week. The magnetic toner contains toner particles, each of which contains a binder resin and a magnetic iron oxide particle, in which the binder resin has a polyester unit, the toner has i) a dielectric loss factor at 40° C. and 100 kHz of 0.50 pF / m or more but 0.90 pF / m or less, and ii) a true specific gravity of 1.50 g / cm3 or more but 1.85 g / cm3 or less.

The invention provides a non-fermented dipped seasoned preserved vegetable production method and belongs to the technical field of food processing. The non-fermented dipped seasoned preserved vegetable production method comprises the steps of selecting and slicing specific leaf mustards, then performing pickling and desalination, meanwhile preparing seasoning liquid to enable relative dielectric constant, dielectric loss factor and conductivity of the seasoning liquid at the1Hz frequency to be within a certain range, charging the sliced leaf mustards into a glass jar, dipping the sliced leaf mustards in the seasoning liquid, arranging the whole glass jar in two square parallel plates, connecting the parallel plates to two poles of a power function signal generator, performing processing at room temperature, then taking out and draining the leaf mustards, instantly performing vacuum package with bags, adding sesame oil into the bags, and finally processing products in an ultraviolet radiation sterilization device to obtain finished seasoned preserved vegetable products. The non-fermented dipped seasoned preserved vegetable production method is suitable for production of high-quality non-fermented instant seasoned preserved vegetable and is short in period and standard compared with a traditional process, and due to the fact that materials are carefully selected, the finished products produced by means of the production method are fine and smooth in taste and completely integrate flavored, peppery and salty taste.

The invention provides a low dielectric PBT / PETG alloy nanometer injection molding composite material as well as a preparation method and application thereof. The preparation raw materials of the PBT / PETG alloy nanometer injection molding composite material comprise the following components in parts by weight: 30 to 50 parts of PBT resin, 30 to 50 parts of PETG resin, 30 to 40 parts of glass fiber, 0.2 to 0.8 part of an antioxidant, 1 to 2 parts of a lubricating agent, 0.3 to 0.5 part of an anti-UV agent and 3 to 8 parts of a compatilizer. The PBT / PETG alloy nanometer injection molding composite material has high mechanical performance, heat resistance, chemical resistance and machinability, has relatively low dielectric constant and relatively low dielectric dissipation factor, and is applicable to the preparation of low dielectric materials or electric equipment products.

The invention discloses a method for measuring dielectric loss factor and insulation resistance of a power transformer. The method aims at resolving the problem that the existing manual mode for disassembling and assembling connection wires costs time and labor and can easily cause measurement errors even safety hazards due to error wire connection. The method includes high voltage relays, a switching switch, a dielectric loss measurement inverse connection module, a dielectric loss measurement face connection module and an insulation resistance measurement module. The method includes that connecting windings on the same side of the transformer and in short circuit with the corresponding high voltage relays with the number of the high voltage relays corresponding to the turn number of the windings of the transformer, switching the high voltage relays of corresponding windings according to the national power industry standard and the test regulation requirement, switching the high voltage relays that the windings to be measured correspond to to high voltage, switching the high voltage relays that the windings not to be measured correspond to to the ground end and utilizing the switching switch to select corresponding modules. The method is capable of achieving automatic measurement, reducing measurement errors, reducing working intensity and improving working efficiency.

The invention provides a resin composition of an insulating layer which has excellent dielectric loss factor, excellent thermal expansion coefficient, excellent elongation at break, surface roughness and peeling strength. The resin composition comprises the components of (A) epoxy resin, (B) active ester compound, (C) carbodiimide compound, (D) thermoplastic resin and (E) inorganic filling material, wherein when the nonvolatile component in the resin composition is set to 100% by mass, the content of the component (E) is above 40%.

The invention discloses an insulation diagnostic method for high-voltage equipment in a charged operating state. According to the method, by means of the electromagnetic induction principle, impact sweep frequency pulse signals output by a frequency conversion power signal source are coupled into the high-voltage equipment through a secondary loop of detected high-voltage equipment, then inductive coupling is carried out on leakage currents after the impact sweep frequency pulse signals are coupled into the detected high-voltage equipment through the loop, and equivalent earth impedance or dielectric loss factors of the high-voltage equipment operating with electricity are calculated by detecting release features of energy generated when the impact sweep frequency pulse signals are coupled and injected to an equivalent electrical loop of the high-voltage equipment, so that whether insulation breakdown discharge to the ground from the high-voltage equipment exists is analyzed. In comparison with the prior art, operating personnel do not need to be close to the primary high-voltage end of the equipment, synchronous transmitting and collecting are carried out by means of a frequency conversion test signal transmitting source and a corresponding receiver, the capacity of resisting disturbance is high, and the insulation state of the high-voltage equipment can be detected with high sensitivity on the condition of not cutting off the electricity.

A local coil unit for a magnetic resonance apparatus, which radiates a radio-frequency field into an examination subject, has a housing and at least a part of the housing is formed of an insulating dielectric material that passively compensates for an inhomogeneity in the high-frequency field in the subject. The material has a relative dielectric value εr of greater than 50, preferably greater than 100, and a dielectric loss factor tan δ of less than 2.5×10−2, preferably less than 1×10−3. In the dielectric material displacement currents are generated which create an additional magnetic field that compensates for the minima in the B1 field as a result of the eddy currents arising in the patient due to the radio-frequency radiation.

The present invention relates to a thermosetting low dielectric resin composition, a laminate for use in printed wiring, a laminate for a circuit, and the like. The present invention's thermosetting low dielectric resin composition contains a specific siloxane denatured polyimide, a compound having two or more allyl or methylallyl groups, and a compound having two or more maleimide groups. This resin composition adheres extremely well to metals with a low dielectric constant and low dielectric dissipation factor, and demonstrates very little scattering of the resin during operational processes like punching or cutting. By using laminates or laminates for circuits that employ this resin composition, electrical signals can be propagated more quickly, enabling signals to be processed at faster speeds. In addition, the present invention can be applied to the formation of miniaturized circuit wiring, and is suitably employed in electronic devices employed in the high frequency region, and, in particular, in electronic devices that must be made smaller and lighter in weight.

The invention discloses a method for estimating the low-frequency dielectric loss of a paper oil insulation system based on parameter identification. Firstly, an XY model is used for simulating the polar characteristics of the transformer paper oil insulation system, a paper oil insulation system XY model equivalent circuit is established, and a relation expression among the circuit parameter, the characteristic quantity complex capacitance and the dielectric loss factor of the XY model equivalent circuit is established; a frequency domain dielectric spectrum method is used for measuring the complex capacitance and the dielectric loss factor of the paper oil insulation system of a field transformer; parameterization is conducted on the equivalent circuit model through the measured complex capacitance of the high-frequency section and the dielectric loss characteristic quantity, and a mathematical optimization model of parameter estimation is established; an improved particle swarm optimization algorithm is used for distinguishing the parameter value of the XY model equivalent circuit with four polar branch circuits; finally, the distinguished parameter value of the XY model equivalent circuit is used for calculating the complex capacitance and the dielectric value of the low-frequency section of the paper oil insulation system, and a frequency domain dielectric spectrum in a wide range is obtained. According to the method for estimating the low-frequency dielectric loss of the paper oil insulation system based on parameter identification, the paper oil insulation state of the large power transformer can be rapidly estimated based on the frequency domain dielectric spectrum method.

The invention discloses a method and a device for monitoring main insulation of three phases of cables under intersection and interconnection of metal protective layers on line, relates to a method and a device for monitoring the main insulation of the three phases of cables on line, and aims to solve the problem that the conventional method and the conventional device cannot be used for monitoring the insulation performance of the three phases of cables under intersection and interconnection of the metal protective layers on line. Current flowing through wire cores at two ends of each phase of cable is measured by using two current transformers; a difference value is calculated, so that a current value flowing through the main insulation of the cable is obtained; due to measurement for three phases of voltage by a voltage transformer, a dielectric loss factor of the main insulation of each phase of cable can be monitored on line; and therefore, the main insulation of the three phases of cables can be monitored on line. A plurality of paths of synchronous analog / digital conversion chips at two ends are controlled to perform synchronous sampling through a global positioning system (GPS) satellite synchronous signal, and calculation is performed in a computer, so that the main insulation of the three phases of cables under intersection and interconnection of the metal protective layers can be monitored on line. The method and the device are suitable for on-line monitoring of the insulation performance of the three phases of cables under intersection and interconnection of the metal protective layers.

The invention discloses a polymer modified graphene / polyvinylidene fluoride high-dielectric composite material and a preparation method thereof. The composite material is prepared by taking polyvinylidene fluoride as a matrix and taking graphene subjected to graft modification by aminosilane and polymer sequentially as dielectric enhancement functional filler through solution blending, electrostatic spinning and laminar hot-press molding sequentially. On the basis of dual regulation of interface and spatial microstructures, uniform dispersion of high-filling-volume graphene filler in the polyvinylidene fluoride matrix is effectively realized according to a graphene surface polymer grafting modification and electrostatic spinning combined method, and the dielectric constant of the obtainedgraphene / polyvinylidene fluoride composite material is evidently increased while a small dielectric dissipation factor is achieved, so that the polymer modified graphene / polyvinylidene fluoride high-dielectric composite material is applicable to fields of embedded capacitors, high-energy-density energy accumulators and the like.

A class of ceramic compositions according to the formula Pb(1-z)Mz(Mn1 / 3Sb2 / 3)x(ZryTi1-y)1-xO3 where M is selected to be either Sr or Ba, x is selected to be between 0.01 and 0.1, y is selected to be between 0.35 and 0.55, and z is selected to be between 0.01 and 0.10. In some embodiments of the above composition, one or more dopants is added to the compositions. The dopant(s) may be selected from the group comprising: PbO, CeO2, SnO2, Sm2O3, TeO2, MoO3, Nb2O5, SiO2, CuO, CdO, HfO2, Pr2O3, and mixtures thereof. The dopants can be added to the ceramic composition in individual amounts ranging from 0.01 wt % to up to 5.0 wt %. The preferred ceramic compositions exhibit one or more of the following electromechanical properties: a relative dielectric constant (ε) of between 1200 and 2000, a mechanical quality factor (Qm) of between 1500 and 2800; a piezoelectric strain constant (d33) of between 250-450 pC / N, a dielectric loss factor (tan δ) of between 0.002-0.008 and a thickness electromechanical coupling coefficient (kt) of between 0.45 and 0.7.

The invention discloses a preparation method of a polytetrafluoroethylene copper-clad plate. The preparation method comprises the following steps: 1, evenly mixing raw material ingredients of polytetrafluoroethylene powder, a lubricating agent, ceramic powder and short glass fiber and curing; 2, moulding pressing to prepare a preform; 3, calendering to obtain a raw substrate and then drying; 4, covering the two sides of the raw substrate by copper foils, sintering, maintaining pressure and then cooling to the room temperature to obtain the polytetrafluoroethylene copper-clad plate. The preparation method replaces a preparation mode applying PTFE dispersion liquid to coating and impregnating and avoids harm of toxic fluoride, nitric oxide and the like; a good filler dispersing effect, evenness in mixing and good dimensional stability of a product are achieved. By means of reasonable matching, the prepared PTFE copper-clad plate has different dielectric constants from 2.6 to 8.6 MHz, a dielectric loss factor is smaller than or equal to 0.003, the peel strength is greater than or equal to 1.7 kN / m, and overall performance can meet the use requirement. The preparation method disclosedby the invention has the advantages of simple technological process and ability in meeting the requirement of industrial batch product.