565 results about "Softening point" patented technology

The invention discloses copper-containing slurry suitable for high-temperature sintering and a preparation method thereof, and the copper-containing slurry comprises the following components in percentage by mass: 10-80% of copper powder, 0-80% of silver powder, 0.2-1% of low-softening-point glass powder, 0-3% of high-softening-point glass, 15-20% of an organic carrier and 0.5-3% of an organic auxiliary agent, the low-softening-point glass powder is of a Pb-Te-Li system, the softening temperature ranges from 250 DEG C to 350 DEG C, and the softening temperature is lower than the decomposition temperature of the organic coating agent on the surface of the copper powder. The preparation method comprises the following steps: adding the components according to the ratio, stirring until the components are uniformly dispersed, grinding and sieving to obtain the copper-containing slurry suitable for high-temperature sintering. According to the prepared copper-containing slurry, the low-softening-point glass powder is adopted as a key component, a liquid-phase protection layer is formed in the high-temperature sintering process, oxidation and diffusion of copper are effectively inhibited, and the oxidation resistance and the conductive stability of the copper-containing slurry are improved. Meanwhile, the slurry has good flowability and printing performance, and can meet the requirements of the photovoltaic industry for efficient and low-cost conductive materials.

The invention relates to the technical field of ceramics, and discloses an aluminum oxide ceramic glaze based on domestic waste ceramics, and a preparation method and application thereof. The aluminum oxide ceramic glaze comprises the following raw materials in parts by weight: 28-42 parts of domestic waste ceramic, 25-30 parts of kaolin, 6-12 parts of calcined talc, 3-7 parts of borax, 6-14 parts of aluminum oxide, 3-5 parts of zirconium oxide, 1-3 parts of lanthanum oxide and 3-6 parts of self-repairing particles. The self-repairing particles comprise mesoporous alumina doped with Si and Zr, and V2O5-B2O3-TeO2 series glass which is filled in pores of the mesoporous alumina and has a softening point of 200-300 DEG C. After the glaze is applied to the surface of the aluminum oxide ceramic to form a glaze layer, the insulativity of the aluminum oxide ceramic can be effectively improved, meanwhile, the high bonding stability between the glaze layer and the aluminum oxide ceramic can be achieved, and the problems that the insulativity is greatly reduced and the glaze layer cracks during heat circulation are solved.

To provide a lead with an insulating resin film with which, when applied to a battery, it is possible to eject a gas generated in a region sealed by the outer packaging of the battery to the outside of the region sealed by the outer packaging.SOLUTION: Provided is a lead with an insulating resin film comprising a conductor and an insulating resin film, wherein, when an axis extending along two sides facing each other is defined as an axis X and an axis crossing the axis X is defined as an axis Y with the conductor viewed from above, the insulating resin film is disposed so as to cover the conductor crossing it along the axis X and not to cover both ends of the conductor that are along the axis Y so as to extend off both ends of the conductor and overlap. The insulating resin film has a first layer being in contact with the conductor, and a second layer. The second layer includes a base resin composed primarily of polypropylene, and one or more kinds of additive component selected from a rubber component and an elastomer component. The melting point of the base resin is 110°C to 130°C inclusive, and the softening point of the additive component is 130°C or below. The second layer contains 10 mass% to 40 mass% inclusive of the additive component.SELECTED DRAWING: Figure 3A

A glass material with low refractive index and radiation resistance, method for preparing the same, and applications thereof. The glass material consists of the following components by mole percent: 60-80% SiO2, 2-10% B2O3, 0.1-1% CeO2, 5-10% Na2O, 2-10% K2O, 1-8% Al2O3, 0-2% CaF2, 0-1% As2O3, and 1-5% alkaline earth metal oxides, wherein the alkaline earth metal oxides are selected from at least one of BaO, SrO, CaO, and MgO. The glass material has a refractive index of ≤1.47, a glass transition temperature of ≤550° C., a yield point temperature of 645° C., a softening point temperature of ≤748° C., and a coefficient of thermal expansion of (82-87)×10−7 / ° C. After exposure to a 4700 Gy dose of X-ray radiation, the transmittance decreases by ≤2%. The glass material can be used as cladding glass material for the preparation of optical glass fibers and fiber panels, capable of meeting the requirements for radiation environment applications.

A preparation method of high-strength and high-density isostatic pressing graphite comprises the following steps: firstly, starting from raw materials, modifying aggregate to increase the specific surface area of the aggregate; secondly, starting from a core process mixing and kneading technical mechanism, asphalt with a higher softening point is adopted as a binder to ensure that the binder asphalt is in contact with the aggregate in a molten state, so that the binder asphalt can be more and more uniformly combined with the aggregate, and therefore, the volume density of the isostatic pressing graphite is improved, the resistivity is reduced, and the strength is improved; the volume density of the obtained isostatic pressing graphite is larger than or equal to 1.5 g / cm < 3 >, the compressive strength is larger than or equal to 80 MPa, the breaking strength is larger than or equal to 40 MPa, and the resistivity is 25-46 omega.m. Compared with the traditional process, the process provided by the invention has the advantages that multiple dipping and roasting processes are reduced, the production period is shortened, and the production efficiency is higher.

The present invention relates to the field of carbon-carbon composite materials, and discloses a carbon-carbon composite material, a carbon-ceramic composite material, an anti-oxidation coating, and an aircraft brake disc. The anti-oxidation coating comprises components by weight: 150 parts of an aqueous solution of aluminum dihydrogen phosphate with a content of 37-43%, 70-130 parts of tin powder, 60-120 parts of silicon carbide powder, 15-60 parts of glass powder with a softening point of 600°C-900°C, 15-50 parts of kaolin, and 10-30 parts of boron carbide powder. The anti-oxidation coating can form a coating with good thermal stability and chemical stability by accurately proportioning and mixing a plurality of materials, and can protect the carbon-carbon composite material from oxidation under a high temperature environment.

To provide an ultra-low temperature vitrified bond capable of having relatively high porosity and maintaining completeness of a tissue structure of pores by keeping a satisfactory mechanical strength, decreasing a sinter temperature to 400°C at a minimum, decreasing a softening point temperature of a bond to 320°C at a minimum and keeping actions of binding and fixing of a vitrified bond before burning down a polymer pore-forming agent and a polymer temporary binding agent.SOLUTION: An ultra-low temperature vitrified bond contains as components in mass percentage: Bi2O3 in 40 to 80%; B2O3 in 5 to 15%; ZnO in 10 to 35%; SiO2 in 0 to 5%; Li2O in 0.5 to 3%; TiO2 in 0 to 5%; CaF2 in 2 to 10%; and Y2O3 in 0 to 5%.SELECTED DRAWING: None

The invention provides a thermoplastic hot melt adhesive for bonding cover plates of household appliances and a preparation method of the thermoplastic hot melt adhesive. The thermoplastic hot melt adhesive for bonding cover plates of household appliances comprises the following components in parts by mass: 40-70 parts of a high-polarity thermoplastic elastomer; 5 to 10 parts of a copolymer containing amorphous alpha-olefin; 10 to 50 parts of tackifying resin with a high softening point; 0.5 to 2 parts of an antioxidant; 0.5 to 2 parts of a light stabilizer; 0.2 to 0.5 part of a silane coupling agent; wherein the high-polarity thermoplastic elastomer is at least one of TPU, EAA, TPEE, ACM and PA. The bonding performance is improved through the high-polarity thermoplastic elastomer; the copolymer containing the amorphous alpha-olefin promotes wetting and permeation on the surface of an adhered object, so that the adhesion is improved, and the toughness of the high-temperature-resistant hot melt adhesive is improved; physical cross-linking curing is carried out through temperature reduction, the curing process is not directly influenced by humidity, and the sealing requirement of sizing equipment for water vapor is reduced.

Non-amorphous hard carbons are produced by treating a hydrocarbon feedstock comprising asphaltenes to increase its softening point and producing an asphaltenes-based precursor material, purifying asphaltenes from the precursor material, treating the asphaltenes to increase its softening point, and oxidizing and pyrolyzing the asphaltenes. The asphaltenes can be powdered or spun into fibers prior to oxidation and pyrolysis. The non-amorphous hard carbons can have an d002-spacing larger than 0.35 nm and a ratio of ID / IG in their Raman spectra greater than 1.0.

The invention provides a dimer acid type polyamide hot melt adhesive and a preparation method thereof. The polyamide hot melt adhesive comprises the following components in parts by weight: 50-90 parts of dimer acid, 5-40 parts of dicarboxylic acid, 45-130 parts of diamine, 1-10 parts of a catalyst and 5-20 parts of an antioxidant. The polyamide hot melt adhesive disclosed by the invention has relatively high softening point and melt viscosity, the adhesive property of the polyamide hot melt adhesive can be improved, and the polyamide hot melt adhesive has relatively high tensile strength and elongation at break, so that the polyamide hot melt adhesive is excellent in mechanical property and relatively wide in application range.

The invention relates to the technical field of optical element machining, in particular to an HUD free-form surface mirror machining method which comprises the following steps of S1, substrate selection and cutting, S2, edge treatment, S3, first-stage hot bending forming, S4, second-stage hot bending forming and S5, grinding. According to the machining method disclosed by the invention, through cooperative use of the first-stage hot bending forming and the second-stage hot bending forming, machining operation of the free-form surface mirror with the large size, the large curvature and the small thickness can be achieved; meanwhile, through the two-stage hot bending forming process, primary forming is conducted through first-stage hot bending forming, pressure maintaining is conducted near a softening point through second-stage hot bending forming, the glass is evenly heated and stressed, residual stress is effectively released, the surface type is promoted to present an ideal gradual change trend, edge distortion is greatly reduced, and the high-precision surface type of the final curved mirror is ensured.

The present invention relates to a tread of a tyre having a tread pattern with a longtotal index (As) equal to or less than 17; said tread being characterized in that it is made up of a rubber composition comprising: (a) a crosslinkable unsaturated chain polymer base comprising from 10 to 50 phr of a modified styrene-butadiene copolymer rubber having a glass-transition temperature (Tg), measured by differential scanning calorimetry, of −50° C. or less; (b) a filler comprising 40 to 100 phr of silica; (c) a plasticizer system comprising a hydrocarbon resin and from 8 to 25 phr of octyloleate; and (d) a vulcanization system; said hydrocarbon resin having a softening point of 110° C. or higher, and an average molecular weight comprised between 700 and 1500 g / mol.

The invention provides a prebaked anode with high compressive strength. The prebaked anode comprises the following raw materials: 68-85 parts by mass of calcined petroleum coke particles; 12-25 parts by mass of a modified coal pitch binder, wherein the softening point of the modified coal pitch binder is 105-115 DEG C; and 0.3-0.8 part by mass of a whisker reinforcing agent. The production process comprises the following steps: calcining, crushing and grading, modifying fine powder, preparing a binder, mixing and kneading, forming and roasting. The prebaked anode has the advantages that through multi-stage material collaboration and process innovation, under the condition that an existing production line is not changed at all, the core contradictions that the prebaked anode is insufficient in strength, poor in conductivity and poor in high-temperature stability are synchronously solved.

The invention relates to a low-softening-point spinnable mesophase pitch and a continuous production process thereof, and belongs to the technical field of pitch-based carbon materials. The technical problems of low purity, high softening point, non-uniform structural composition, high production cost and the like of the mesophase pitch prepared by a process for producing the mesophase pitch from aromatic hydrocarbon-rich heavy oil in the prior art are solved. According to the continuous production process disclosed by the invention, coal-based or petroleum-based aromatic hydrocarbon-rich heavy oil is taken as a raw material, raw oil refining is realized through a continuous solvent extraction process, and shallow polycondensed asphalt is prepared by adopting a multi-section heating tubular reactor through a thermal polycondensation process; then the pitch is subjected to a supercritical or subcritical extraction process at a certain temperature and pressure to obtain the mesophase pitch with enriched polycyclic aromatic hydrocarbon molecules with low softening point, narrow molecular weight distribution and uniform structural composition, and the mesophase pitch has excellent spinning performance, so that the prepared carbon fiber has excellent mechanical properties and is suitable for industrial production. The high-value utilization of the aromatic hydrocarbon-rich heavy oil is realized.

The invention relates to an electronic component material technology, and aims to provide an LTCC (Low Temperature Co-Fired Ceramic) material with low dielectric constant and low dielectric loss and a preparation method thereof. The LTCC material is prepared from zinc borosilicate glass and zinc borosilicate microcrystalline glass with different softening point ranges, a ceramic filler, silicate and a metal oxide through ball milling, mixing, modeling and sintering, and the material contains Zn2SiO4 with a devitrified phase. According to the invention, two kinds of zinc borosilicate glass with different softening points are adopted as cooling assistants, and a devitrified phase Zn2SiO4 is generated through reaction in the sintering process, so that the problem of large dielectric loss of a composite system caused by more glass phases can be effectively improved; by flexibly regulating and controlling the content of each component and the components of the auxiliary materials, the sintering characteristics of the glass internal component regulation and control material are optimized, and the success rate of matching and co-firing of the material and silver is further improved; meanwhile, the sintering window is relatively wide, so that good quality stability of the product is favorably kept; the dielectric loss of the composite system is reduced by doping the nucleating agent, and the volume shrinkage process of the material is regulated and controlled.

The invention relates to the technical field of coiled materials, in particular to an asphalt waterproof coiled material and a preparation method thereof. The preparation method comprises the following steps: firstly, coating a boron nitride nanosheet with porous alkenyl organic silicon constructed by adopting phenyltrimethoxysilane, 1, 4-bis (triethoxysilyl) benzene and vinyltrimethoxysilane as a framework, adding the boron nitride nanosheet and SBS into asphalt to obtain modified asphalt, then coating the modified asphalt on the surface of a polyester base, and finally coating the modified asphalt on the surface of the polyester base. And flattening and cooling to obtain the waterproof coiled material. The porous alkenyl organosilicone-coated boron nitride nanosheets adopted in the invention significantly improve the penetration, softening point and ductility of asphalt, and improve the tensile property, heat resistance and waterproofness of the waterproof coiled material prepared from the asphalt, and the waterproof coiled material is suitable for long-term use in a complex environment.

To provide a hot-melt adhesive composition which exhibits a low reactivation temperature, and superior thermal resistance and workability.SOLUTION: The hot-melt adhesive composition comprises: polyolefin component A with a melting point of 120 to 150°C and a melting enthalpy of 60 to 100 J / g; polyolefin component B having a melting point of 80 to 120°C and a melting enthalpy of less than 60 J / g, polymerized by a single-site catalyst; and tackifying resin component C having a softening point in the range of 130 to 150°C.SELECTED DRAWING: None

The invention provides a preparation method of chlorinated paraffin 70 with a high softening point, and belongs to the technical field of chlorinated paraffins.The preparation method comprises the steps that S1, mixed wax is provided, and raw materials of the mixed wax are Fischer-Tropsch wax and petrochemical wax; s2, feeding the mixed wax into a reactor, then turning on an ultraviolet lamp in the reactor for irradiation, after liquid chlorine is gasified to form chlorine, feeding chlorine into the reactor, heating and carrying out segmented control reaction; s3, after the reaction is finished, blowing air into the reactor, then washing a reaction product with water, and then adding a compound stabilizer into a crude product obtained by washing with water, so as to obtain chlorinated paraffin 70; the chlorine content of the chlorinated paraffin 70 is not less than 69.5%, the softening point is not less than 98 DEG C, and the acid value is not more than 0.1 mgKOH / g. According to the method, hot chlorination and photo-initiation are combined, so that the chlorine content and the softening point of the product are controllable, the production efficiency is high, the reaction speed is high, the reaction temperature is reduced, the production period is shortened, and the product quality is stable.

The invention provides aluminum paste overprinted on a BC battery silver grid line, a preparation method of the aluminum paste and the BC battery grid line, and belongs to the technical field of BC batteries. The aluminum paste comprises 65-90 parts by mass of aluminum powder; 2-10 parts by mass of glass powder; 2-5 parts by mass of an organic resin; 10-20 parts by mass of a solvent; 0-2 parts by mass of an additive; wherein the glass powder adopts bismuth-boron glass powder with the softening point of 400-500 DEG C. By adopting the bismuth-boron glass powder with low softening point temperature, silver-aluminum alloy is reduced during sintering at the medium-high temperature of 580-630 DEG C, the silver-aluminum lap resistance is reduced, the low composite level of the grid line is ensured, the electrical property of the grid line is improved, the replacement of silver paste by aluminum paste in a BC battery is realized while the light conversion efficiency is high, and the cost is reduced.

The invention relates to the technical field of hot-melt pressure-sensitive adhesives, in particular to a hot-melt pressure-sensitive adhesive special for instillation type coating and a preparation method of the hot-melt pressure-sensitive adhesive. The hot-melt pressure-sensitive adhesive is prepared from the following raw materials in parts by mass: 25 to 35 parts of styrene block copolymer, 40 to 50 parts of tackifying resin, 20 to 30 parts of plasticizer and 0.1 to 0.5 part of antioxidant. Wherein the styrene block copolymer is preferably compounded from S-1528, 4411ND and 6241A, the tackifying resin is preferably hydrogenated rosin glyceride with the softening point of 85-90 DEG C, and the plasticizer is medical white oil. The 180-degree peel strength of the prepared product is larger than 5.0 N / 25 mm, the 180-degree viscosity is 2000-6500 cps, the instillation precision can reach + / -8 microns, and the product has excellent adhesive performance and process adaptability and is suitable for instillation type coating scenes.

The present invention relates to an expansion adhesive sheet comprising: a base material; two thermal expansion adhesive layers respectively disposed on both sides of the substrate; the expansion bonding sheet is characterized in that the expansion bonding sheet further comprises a release paper layer which is arranged on the surface of one thermal expansion bonding agent layer; and the release paper is double-sided release paper. The invention has the following beneficial effects: during winding, only one layer of release paper (the upper layer or the lower layer) is peeled off, so that the molding equipment is simplified, the winding can be carried out at a higher temperature without using measures for reducing the product performance, and the adhesion is avoided during winding; compared with a five-layer structure attached with non-woven fabric or sprayed with a release agent, the operation convenience is improved, and the requirements of instruments and equipment are simplified; according to the scheme, the degree of freedom of adhesive formula design can be improved at the same time, and the softening point of the expansion bonding layer can be reduced on the premise of ensuring that the expansion bonding layer is non-viscous at room temperature.

The invention relates to a preparation method of homogeneous graphite and the homogeneous graphite, and belongs to the technical field of graphite material preparation. The preparation method comprises the following steps: taking raw material fine powder of calcined pitch coke or petroleum coke as aggregate; the raw material fine powder is divided into n parts of fine powder with different weights, the n parts of fine powder are respectively mixed and kneaded with asphalt with different softening points and different amounts to obtain n parts of paste, one part of the paste with the largest weight part of the raw material fine powder is ground into paste fine powder with the average particle size of 10-100 microns, and the other n-1 parts of the paste are subjected to heat preservation; forming the paste fine powder to obtain a pre-pressed green body, sequentially coating (n-1) layers of paste on the surface of the pre-pressed green body, and performing isostatic pressing to obtain a primary green body; and carrying out secondary forming, and carrying out post-treatment to obtain a homogeneous graphite product. According to the method, the surfaces of the pre-pressed blanks are coated with different types of paste materials in a coating mode, so that the green bodies have certain differences from inside to outside, the inside and outside differences caused by follow-up processing to the green bodies are counteracted, and the whole graphite product has the characteristic of uniformity.

To provide a busbar electric wire that allows insulation to be maintained for a certain period of time or longer even under high-temperature conditions and enables reduction of breakage risk during forming processing while retaining manufacturability.SOLUTION: A busbar electric wire 1 includes: a metal busbar 10 formed in a flat shape from pure copper; and an insulator 20 covering the metal busbar 10. The insulator 20 has: a silicone resin 21 serving as a main component; and a fire-resistant filler 22 composed of a substance having a second softening point higher than a first softening point, the first softening point being a softening point of the silicone resin 21. The tear-strength / density is 11.5 kN cm3 / m g or more and 23.0 kN cm3 / m g or less, and a residual amount after combustion in heating exceeding the first softening point and below the second softening point is 36 wt.% or more relative to before combustion.SELECTED DRAWING: Figure 2

A method of manufacturing a bonded body includes: a preparation step of interposing a sealing material (6) containing glass between a highly thermal conductive substrate (2) and a glass substrate (3); and a bonding step of forming a sealing layer (4) by irradiating the sealing material (6) with laser light (L). The bonding step includes: a first heating step of preheating the sealing material (6) at a temperature lower than a softening point of the sealing material (6) or a temperature at which the sealing material (6) is prevented from softening and flowing by irradiation with the laser light (L); and a second heating step of heating, after the second heating step, the sealing material (6) at a temperature equal to or higher than the softening point of the sealing material (6) or a temperature at which the sealing material (6) softens and flows by irradiation with the laser light (L).

The invention relates to the field of adhesive preparation, in particular to a preparation method of modified C5 petroleum resin and application of the modified C5 petroleum resin in a hot melt adhesive. According to the method, high-quality synthesis of the C5 petroleum resin under mild conditions is realized by adopting the eutectic solvent catalyst containing AlCl3, so that the softening point of the synthesized petroleum resin is relatively high, and the chromaticity is relatively low; by combining the use of an isoamylene / maleic anhydride combined modifier system, the performance of the C5 resin can be comprehensively improved, and the C5 resin can be more easily matched with the requirements of application scenes, especially the application in hot melt adhesives.

The invention discloses alkali-free glass with low reheat shrinkage rate as well as a preparation method and application thereof, and the glass is prepared from the following raw materials in percentage by mass: 60 to 65 percent of SiO2, 17 to 21 percent of Al2O3, 0 to 2 percent of B2O3, 4 to 8 percent of SrO, 3 to 5 percent of CaO, 4 to 7 percent of MgO, 0 to 3 percent of BaO and 0 to 2 percent of SnO. The alkali-free glass which is high in strain point, low in softening point and high in ultraviolet transmittance and meets the requirement of a polycrystalline silicon process is prepared by adopting an overflow down-draw method process under a conventional annealing condition according to a raw material ratio, on one hand, by increasing the content of SiO2, the strain point of the glass is increased, and the reheat shrinkage rate is reduced at the same time; on the other hand, BaO is introduced to regulate the density of the glass and improve the strain point temperature of the glass, the reheat shrinkage rate (600 DEG C / 1h) of the prepared alkali-free glass is below 35ppm, the strain point reaches above 707 DEG C, the softening point temperature is about 820 DEG C, the thermal expansion coefficient is 3.4 * 10 <-6 >-4.0 * 10 <-6 > / DEG C, the density is 2.52-2.57 g / cm < 3 >, the hardness is 685-712kgf / mm < 2 >, and the transmittance reaches above 74% when the visible light wavelength lambda is 308nm.

This inorganic composition article is characterized by: being obtained by tempering a crystallized glass which contains, as the main crystal phase thereof, at least one selected from α-cristobalite and an α-cristobalite solid solution, and in which, when expressed as mass % of respective oxides, the contained amount of component SiO2 is not less than 45.0% but less than 68.0%, the contained amount of component Al2O3 is 3.0-15.0%, the contained amount of the component Li2O is 3.0-10.0%, the contained amount of component B2O3 is more than 0% but not more than 10.0%, the contained amount of component P2O5 is more than 0% but not more than 10.0%, the contained amount of the component ZrO2 is more than 0% but not more than 10.0%; and the mass ratio of SiO2 / (B2O3+Li2O) is 3.0-10.0; having a compressive stress layer on the surface thereof; and having a softening point (SP) of lower than 795° C.

The invention discloses a method for improving molecular weight uniformity of polycarbosilane, and relates to the field of materials and chemical engineering. A packed distillation tower is additionally arranged in a polycarbosilane (PCS) reaction kettle, low-boiling-point small molecules in the reaction kettle in the synthesis process are distilled and separated out through the packed distillation tower, precise separation of the small molecules is achieved in combination with three-stage heating and a corresponding distillation mode, and the low-medium-boiling-point small molecules are removed in real time through rectification separation. The content of low-boiling-point components easily causing molecular weight fluctuation in the PCS is reduced, the randomness of the softening point of the PCS product is remarkably reduced, and the quality stability of the PCS is improved. And the temperature uniformity is improved, a reaction kettle with a larger volume is adapted, the problems of random molecular weight distribution, unstable softening point and the like of the existing PCS are effectively solved, and a reliable process is provided for preparing the high-quality PCS.

The present invention relates to a polyester film with low shrinkage, good adhesion and wear resistance and a preparation method thereof. The polyester film comprises two surface layers and a core layer located between the two surface layers; the material of the surface layer is mainly composed of polybutylene terephthalate and a wear-resistant agent; the material of the core layer is mainly composed of a mixture of polycarbonate and polyethylene terephthalate-1,4-cyclohexanedimethanol. Preparation method: manufacturing surface layer pellets; manufacturing core layer pellets; extruding the melts separately and compounding them in a die head, and then subjecting them to shaping, cooling, pulling and annealing to obtain a polyester film. In the present invention, a core layer structure is introduced by a multi-layer co-extrusion method, and the film has wear-resistant and scratch-resistant functions after film formation, and no coating treatment is required; the core layer structure can achieve a low shrinkage rate and is easy to heat-seal; at the same time, the softening point of the introduced core layer is very low, so that the overall adhesion of the film is strong, and it has good adhesion performance to irregular concave and convex surfaces; the preparation method has a simple process and strong practicality.

To provide a silicone rubber composition capable of forming a silicone heat-shrinkable tube showing excellent shrinkability even under low-temperature heating and having conventional shape retention during storage at room temperature.SOLUTION: A silicone rubber composition for forming a silicone heat-shrinkable tube, comprises: (A) 100 pts.mass of a linear organopolysiloxane having two or more vinyl groups bonded to silicon atoms per molecule, an average degree of polymerization of 3,000 to 50,000, at least 50 mol.% of all substituents being methyl groups, and 0.05 to 5.0 mol.% being vinyl groups; (B) 10 to 100 pts.mass of an organopolysiloxane resin different from the component (A) having a softening point of 100 to 200°C, and an endothermic peak of 50°C to 80°C in differential scanning calorimetry; (C) 5 to 50 pts.mass of powdered silica having a BET specific surface area of 100 m2 / g or more; and (D) an effective amount of a curing agent.SELECTED DRAWING: Figure 1