Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
  • C09D167/08—Polyesters modified with higher fatty oils or their acids, or with natural resins or resin acids

Definitions

• the present invention relates to packaging coating compositions, especially food and beverage packaging coating compositions.
• the packaging coating compositions comprise a solvent borne alkyd resin, and a crosslinker, wherein the solvent borne alkyd resin comprises an aromatic dicarboxlic acid, an aliphatic diol, a fatty acid and bis(hydroxyalkyl) bisphenol A.
• coil coating and/or sheet coating are usually used to apply the coating on the metal container or the material from which the container will be fabricated.
• the coil coating and/or sheet coating refer to a process for coating coil or sheet substrates including stainless steel, tin plated steel, or aluminum substrates with an appropriate composition. Then, the coated substrate can be manufactured into can body, bottom, lid, and/or cover.
• the coating composition also can be applied onto an already formed can body, bottom, lid and/or cover such as by spray coating and/or dip coating the part, and then curing.
• the coating for food and beverage packages usually can be applied on the substrate at high speed, while also providing necessary performance to meet the needs of end users, for example, the formed coating layer should be safe for contacting with food and beverage, and/or have excellent adhesion to the substrate.
• Solvent borne polyester coating is commonly used for packaging coatings because of its excellent mechanical properties, stain resistance and outdoor durability performance.
• the solvent borne polyester coating has a disadvantage in its high VOC content.
• the solvent evaporation during can coating not only causes great energy consumption, but also may be unfriendly to the environment. Therefore, high solid content polyester coatings, which are more environmentally friendly because of their low solvent content, are highly desired.
• the present invention provide a solvent borne alkyd resin, comprising the reaction product of a mixture comprising an aromatic dicarboxylic acid, an aliphatic diol, a fatty acid and bis(hydroxyalkyl) bisphenol A.
• the present invention provides methods for preparing such a solvent borne alkyd resin comprising: mixing an aromatic dicarboxylic acid, an aliphatic diol, a fatty acid, bis(hydroxyalkyl) bisphenol A, and optional solvent, with rapid stirring, and heating the mixture to at least 150°C; heating under reflux, and gradually raising the temperature to at least 240°C, until the reaction mixture becomes transparent; cooling to at least 140°C; and filtering the solid product.
• the present invention provides a solvent borne coating composition, comprising the solvent borne alkyd resin of the present invention, and a crosslinker.
• the present invention provides a package coated with the solvent borne coating composition of the present invention, and a process for coating a package at least in part with the solvent borne coating composition of the present invention.
• the present invention provides a solvent borne alkyd resin, which comprises the reaction product of a mixture comprising an aromatic dicarboxylic acid, an aliphatic diol, a fatty acid and bis(hydroxyalkyl) bisphenol A.
• the present invention also provides a coating composition, which comprises: the solvent borne alkyd resin of the present invention and a crosslinker.
• the aromatic dicarboxylic acid refers to aromatic compounds containing 8-16 carbon atoms and two carboxylic acid functional groups, wherein the aromatic moieties include, but are not limited to, an aromatic moiety derived from benzene, naphthalene, anthracene, and/or xenene.
• the aromatic dicarboxylic acids comprise phthalic acid, isophthalic acid and/or terephthalic acid.
• Embodiments wherein the aromatic dicarboxylic acids comprise isophthalic acid and/or terephthalic acid are particularly suitable.
• the aliphatic diol refers to aliphatic compounds containing 2-10 carbon atoms and two hydroxyl functional group.
• the aliphatic diol comprises propyl glycol, butyl glycol, pentyl glycol, neopentyl glycol and/or hexyl glycol.
• the aliphatic diol comprises propyl glycol, butyl glycol, pentyl glycol and/or neopentyl glycol, such as butyl glycol and/or neopentyl glycol.
• the fatty acid refers to saturated or unsaturated aliphatic compounds containing 6-20 carbon atoms with a terminal carboxy group.
• the fatty acid can be a mixture of several acid compounds with different length of carbon chains.
• the fatty acid comprises soyabean fatty acid, coconut fatty acid, and/or lauric acid.
• the fatty acid comprises soyabean fatty acid.
• the bis(hydroxyalkyl) bisphenol A is a bisphenol A derivative obtained by substituting both of the hydrogen atoms on the hydroxyl groups of bisphenol A with two hydroxyalkyls having 1-6 carbon atoms.
• the two hydroxyalkyl substitutions can be the same or different.
• the two hydroxyalkyls substitutions are the same.
• the bis(hydroxyalkyl) bisphenol A comprises bis(hydroxyethyl) bisphenol A, bis(hydroxypropyl) bisphenol and/or bis(hydroxybutyl) bisphenol A.
• the bis(hydroxyalkyl) bisphenol A comprises bis(hydroxyethyl) bisphenol A, and/or bis(hydroxypropyl) bisphenol, such as bis(hydroxyethyl) bisphenol A.
• the solvent borne alkyd resin based on its total weight, comprises 10-60 wt%, such as 15-50 wt%, or 20-40 wt% of an aromatic dicarboxylic acid.
• the solvent borne alkyd resin based on its total weight, comprises 1-40 wt%, such as 3-30 wt%, or 5-20% of an aliphatic diol.
• the solvent borne alkyd resin based on its total weight, comprises 5-55 wt%, such as 5-45 wt%, 5-35 wt%, or 10-20 wt% of bis(hydroxyalkyl) bisphenol A.
• the solvent borne alkyd resin further comprises a solvent.
• the solvent comprises aromatic hydrocarbons.
• the solvent comprises high boiling point aromatic hydrocarbons.
• the solvent borne alkyd resin based on its total weight, comprises 1-30 wt%, such as 5-25 wt%, 10-20 wt%, or 10-15 wt% of solvent.
• the solvent borne alkyd resin may, in certain embodiments, further comprise a catalyst, which can be any suitable catalyst, such as an organotin compound.
• a catalyst which can be any suitable catalyst, such as an organotin compound.
• the solvent borne alkyd resin based on its total weight, comprises 0-1 wt%, such as 0-0.5 wt%, 0.1-0.3 wt%, or 0.1 wt% of the catalyst.
• the alkyd resin can be prepared in accordance with the following steps:
• the present invention provides a solvent borne coating composition, which comprises a solvent borne alkyd resin of the present invention and a crosslinker.
• the crosslinker can be any crosslinker that reacts with the alkyd.
• the crosslinker comprises an amino resin and/or a blocked isocyanate.
• the amino resin used may be a complex mixture containing different functional groups and molecule types obtained by the condensation between formaldehyde and an amine, and followed by alkylation of the obtained hydroxymethyl with alcohol.
• the amino resin can be butylated amino resin such as cymel 1156, and/or butylated benzene substituted amino resin such as cymel 659.
• the blocked isocyanate is a polyurethane obtained by reacting terminal isocyanate groups with a compound having an active hydrogen atom, and then blocking the -NCO reactive functionality of the product that wil become unblocked during cure.
• the blocked isocyanate can be for example blocked isocyanate Desmodur BL4265.
• the solvent borne coating compositions of present invention can comprise 20-80 wt%, such as 30-70 wt%, or 40-60 wt% of the solvent borne alkyd of the present invention.
• the solvent borne coating composition of the present invention may, in certain embodiments, further comprise a polyester resin.
• the additional polyester may be crosslinked by the same crosslinker as the solvent borne alkyd, while in other embodiments an additional crosslinker may be used; such crosslinker can be selected by one skilled in the art based on the polyester being used.
• the polyester resin used in the present invention can be any suitable polyester resin.
• the polyeseter resin comprises an aromatic dicarboxylic acid and/or anhydride thereof, an aliphatic alcohol, and optionally a catalyst, and/or a solvent.
• the aromatic dicarboxylic acid and/or anhydride thereof can comprise, for example, phthalic acid, isophthalic acid, terephthalic acid and/or anhydride thereof.
• the aromatic dicarboxylic acid and/or anhydride thereof comprises phthalic anhydride.
• the aliphatic alcohol can comprise, for example, monobasic alcohols, diols and triols, such as isooctanol, isononanol, isodecanol, butyl glycol, pentyl glycol, neopentyl glycol, trimethylolpropane, and/or triethylolethane.
• the catalyst if used, can be any suitable catalyst used in the preparation of a polyester, for example, organotin catalyst, such as FASCAT 4201 catalyst from Newtop Chemical Materials Co. Ltd, Shanghai. Any other polyester suitable for use in a packaging coating can also be used.
• the solvent borne coating composition of the present invention may, in certain embodiments, further comprise an epoxy resin suitable for use in packaging coatings, such as those commercially available from Momentive, an example of which is EPON860.
• the epoxy may be crosslinked by the same crosslinker as the solvent borne alkyd, while in other embodiments an additional crosslinker may be used; such crosslinker can be selected by one skilled in the art based on the epoxy being used.
• the solvent borne coating composition of the present invention may, in certain embodiments, further comprises optional ingredients.
• the coating compositions of the present invention comprise a solvent, such as an organic solvent, or a mixture of water and an organic solvent.
• suitable organic solvents include aliphatic hydrocarbons such as solvent oil and a high flash point VM & P Naphtha; aromatic hydrocarbons such as benzene, toluene, xylene, high boiling point aromatic hydrocarbons including S-100A, S-100B, S-100C, S-150, S-180, S-200 available from HUALUN Chemical Industry Co., Ltd, SolvessoTM 100, SolvessoTM 150, SolvessoTM 200 available from ExxonMobil Chemical; alcohols, such as ethanol, n-propanol, isopropanol, n-butanol and the like; ketones, such as acetone, cyclohexanone, methyl isobutyl ketone and the
• the solvent borne coating composition of the present invention comprises aromatic hydrocarbons such as SolvessoTM 100, SolvessoTM 150, and/or alcohols such as propanol and butanol.
• aromatic hydrocarbons such as SolvessoTM 100, SolvessoTM 150, and/or alcohols such as propanol and butanol.
• the solvent used in the coatings of the present invention based on total coating weight, comprises 5-30 wt%, such as 10-25 wt%, or 12-20 wt% of solvent.
• Another optional ingredient is a catalyst to increase the curing or crosslinking rate of the coating composition.
• a catalyst to increase the curing or crosslinking rate of the coating composition.
• an acid catalyst can be used.
• the solvent borne coating composition of the present invention based on its total weight, comprises 0.05 to 1 wt%, such as 0.1 to 0.5 wt% of a catalyst.
• suitable catalysts include dodecylbenzenesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, dinonyl naphthalene disulfonic acid and phenyl phosphonic acid.
• a leveling agent or surfactant is added to a coating composition to decrease surface tension gradients, thereby improve the leveling property of the coating composition.
• Suitable surfactants include, but are not limited to, polydimethylsiloxane, polyether-polyester-modified organic silicone and alkyl-modified organosiloxane.
• the solvent borne coating composition of the present invention based on its total weight, comprises 0.05 to 1 wt%, such as 0.1 to 0.5 wt% of a leveling agent.
• levelling agents useful in the solvent borne coating compositions of the present invention include BYK 358 leveling agent, and/or BYK 300 organosiloxane levelling agent.
• the solvent borne coating composition of the present invention may also include additives commonly used in the coating industry, including, for example colorants, plasticizers, abrasion resistant particles, membrane strengthening particles, flow control agents, thixotropic agents, rheology modifiers, antioxidants, biocides, defoamers, wetting agents, dispersing agents, adhesion promoters, clay, hindered amine light stabilizers, UV light absorbing stabilizers, stabilizers, fillers, grinding vehicle agents and other common additives, or combinations thereof.
• additives commonly used in the coating industry including, for example colorants, plasticizers, abrasion resistant particles, membrane strengthening particles, flow control agents, thixotropic agents, rheology modifiers, antioxidants, biocides, defoamers, wetting agents, dispersing agents, adhesion promoters, clay, hindered amine light stabilizers, UV light absorbing stabilizers, stabilizers, fillers, grinding vehicle agents and other common additives, or combinations thereof.
• solvent borne resin and/or “solvent borne coating composition” refer to resin and/or coating composition which can be dissolved or dispersed in solvent prior to use to form a solution, a dispersion, an emulsion, a suspension and any other suitable forms, wherein the solvent can be an organic solvent and/or a mixture of water and an organic solvent, thereby dissolving or dispersing the resin and/or coating composition components.
• the solvent may be reactive, non-reactive or a mixture thereof.
• the organic solvent is selected to be volatile enough to be substantially completely removed from the coating composition in the curing process by evaporation, for example, such as heating to 150-180 °C for 5-15 minutes.
• the solvent borne alkyd resin and/or coating comprising the same may be substantially free, may be essentially free and/or may be completely free of bisphenol A and derivatives or residues thereof, including bisphenol A and bisphenol A diglycidyl ether ("BADGE").
• a solvent borne alkyd resin and/or coating that is substantially bisphenol A free is sometimes referred to as "BPA non intent" because BPA, including derivatives or residues thereof, are not intentionally added but may be present in trace amounts such as because of impurities or unavoidable contamination from the environment.
• the solvent borne alkyd resin and/or coatings of the present invention can also be substantially free, essentially free and/or completely free of bisphenol F and derivatives or residues thereof, including bisphenol F and bisphenol F diglycidyl ether ("BPFDG").
• BPFDG bisphenol F and bisphenol F diglycidyl ether
• substantially free as used in this context means the solvent borne alkyd resin and/or coating compositions contain less than 1000 parts per million (ppm), "essentially free” means less than 100 ppm and “completely free” means less than 20 parts per billion (ppb) of any of the above compounds or derivatives or residues thereof.
• the solvent borne coating composition of the present invention may be applied to any of the substrates known in the art, for example, automotive substrates, industrial substrates, packaging substrate, floors and furniture.
• the substrate may be metallic or non-metallic.
• the metal substrates include, for example, steel, tin-plated steel, galvanized steel, aluminum, aluminum foil.
• Non-metallic substrates include polymers, plastics, polyester, polyolefm, polyamide, cellulose, polystyrene, polyacrylic acid, poly (ethylene naphthalate ester), polypropylene, polyethylene, nylon, EVOH, polylactic acid, poly (ethylene terephthalate) (PET), polycarbonate, polycarbonate, acrylonitrile butadiene styrene (PC/ABS), polyamide , wood, wood composite panels, cement, stone, glass, paper, cardboard, textiles, leather, including synthetic and natural leathers, as well as other non-metallic substrates.
• the solvent borne coating composition may be applied to steel, tin-plated steel, galvanized steel, aluminum substrates.
• the solvent borne coating composition is applied to food and beverage packages. Accordingly, the present invention is further directed to a substrate coated at least in part with the coating of the present invention, wherein the substrate comprises a package or any part thereof, such as a crown cap.
• the coating composition of the present invention through any standard technique in the art for coating methods, such as electric coating, spraying, electrostatic spraying, dip coating, roll coating, brush coating methods.
• the coating has a dry film thickness of 2-10 ⁇ , such as 3-8um, or 4-6 um.
• the coating composition of the present invention may be used alone or in combination with one or more other coating compositions.
• the coating composition of the present invention may either contain a colorant or not, and can be used as a primer, base coat and/or topcoat.
• the coating composition of the present invention is suitable for package coatings, especially food and beverage package coatings.
• the coating can be applied on metal substrates to delay or prevent corrosion, to provide decorative coatings, and/or to make the metal substrate easier to handle during the manufacturing process.
• the coating can be applied to the inside of the package to prevent the contents of the package from coming into contact with the metal.
• the contact of metal substrate with food or beverages may cause corrosion of the metal subtrate, thereby contaminating the food or beverage, especially when the food or beverage is acidic.
• the coating may also be applied on the outside of the package.
• the solvent borne coating composition of the present invention is suitable for metal sheet material, for example, the metal sheet material for the manufacture of cans, can end, including the can lid, cap and/or bottom.
• the coating is generally applied on the metal substrate before cutting and punching, therefore it generally has good flexibility and scalability.
• the metal substrate is coated with the coating composition on both sides, and then then stamped and formed cans, can lids, bottoms or caps.
• the coating also can be applied after the cans, can lids, bottoms and caps are formed.
• the coating may be resistant to borehole, corrosion, haze and/or blistering.
• Certain coatings of the present invention are particularly applicable for use with coiled metal stock, such as the coiled metal stock from which the ends of cans are made (“can end stock”), and end caps and closures are made (“cap/closure stock").
• coatings designed for use on can end stock and cap/closure stock are typically applied prior to the piece being cut and stamped out of the coiled metal stock, they are typically flexible and extensible. For example, such stock is typically coated on both sides. Thereafter, the coated metal stock is punched. For can ends, the metal is then scored for the "pop-top” opening and the pop-top ring is then attached with a pin that is separately fabricated. The end is then attached to the can body by an edge rolling process. A similar procedure is done for "easy open” can ends. For easy open can ends, a score substantially around the perimeter of the lid allows for easy opening or removing of the lid from the can, typically by means of a pull tab.
• the cap/closure stock is typically coated, such as by roll coating, and the cap or closure stamped out of the stock; it is possible, however, to coat the cap/closure after formation. Coatings for cans subjected to relatively stringent temperature and/or pressure requirements should also be resistant to cracking, popping, corrosion, blushing and/or blistering.
• the present invention also relates to a package, wherein at least a portion of the package is coated with the solvent borne coating composition of the present invention.
• the package is a metal can.
• the term "metal can" includes any type of cans and containers which can accommodate contents. Examples of metal cans include food cans and beverage cans.
• the food cans and/or beverage cans refer to any type of cans and containers accommodating food and/or beverage.
• the metal cans also specifically include a metal can cover, for examples caps including crown caps, and lids including screw down lids.
• the metal can may also be used to accommodate other items, including, but not limited to personal care products, insect sprays, paint, and any other suitable packing contents.
• the term "metal cans" also specifically includes metal caps and/or closures such as bottle caps, screw top caps and lids of any size, lug caps, and the like.
• the metal cans can be used to hold other items as well, including, but not limited to, personal care products, bug spray, spray paint, and any other compound suitable for packaging in an aerosol can.
• the cans can include "two-piece cans" and "three-piece cans” as well as drawn and ironed one-piece cans; such one-piece cans often find application with aerosol products.
• Packages coated according to the present invention can also include plastic bottles, plastic tubes, laminates and flexible packaging, such as those made from PE, PP, PET and the like. Such packaging could hold, for example, food, toothpaste, personal care products and the like.
• the solvent borne coating composition of the present invention may be applied to interior and/or exterior of the package.
• the coating is applied by rolling on sheet or coil substrate, then cured and punched to obtain can end including lid, or cap.
• the solvent borne coating composition of the present invention may be applied on the ink, varnish and/or color decoration layer pre-formed on the can body, top, bottom, lid and/or cap.
• the solvent borne coating composition of the present invention may be wet-on-wet applied on the ink, varnish and/or color decoration layer.
• the alkyd resin and coating comprising the same as described herein, may offer physical properties desirable for packaging coatings, for example low viscosity and/or good levelling, hardness, abrasion resistance and/or flexibility.
• the coating compositions of the present invention also have a lower curing temperature than many packaging coatings used in the art.
• the coating compositions of the present invention cure at a temperature of 150-180°C, such as 155-175°C, such as 160-170°C.
• the ability of the coating compositions of the present invention to be wet-on-wet applied on an ink layer simplifies the coating procedure and saves cost.
• a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
• Example 1 Preparation of a solvent borne alkyd resin
• the alkyd resin was prepared in accordance with the following steps:
• a. isophthalic acid, terephthalic acid, soyabean fatty acid, neopentylglycol, glycerol, hydroxyethyl bisphenol A, butyl glycol, organic tin catalyst, and SolvessoTM 100 were mixed with rapid stirring at 400rpm, and heated to at least 150°C;
• alkyd resin SP0004 hereafter
• Example 2 Preparation of a polyester resin
• the formulation is as below, based on the total weight of the polyester resin:
• the polyester resin was prepared in accordance with the following steps: a. pthalic anhydride, isooctanol, trimethylolpropane, FC 4201 catalyst, xylene, SolvessoTM 150, and ethylene glycol butyl ether were mixed with rapid stirring at 400rpm, and heated to at least 150°C;
• polyester resin SP0001 the polyester resin referred to as polyester resin SP0001 hereafter.
• Example 3 Preparation of an solvent borne coating composition
• the formulation is as below, based on the total weight of the solvent borne coating composition:
• Polyester resin SP0001 10.0%
• the coating composition was prepared in accordance with the following steps:
• auxiliaries including BYK 358 levelling agent, BYK 300 organosilicone leveling agent, lauryl benzenesulfonic acid, and ethylene glycol butyl ether were pre-dissolved in a solvent mixture of SolvessoTM 100, SolvessoTM 150 and butanol; d. the pre-dissolved auxiliaries were added into the mixed resin while stirring; e. the speed was increased to 1000 rep/min, and the mixture stirred for 30 minutes;
• Example 4 Preparation of a solvent borne coating composition
• the formulation is as below, based on the total weight of the solvent borne coating composition:
• Example 3 The coating composition prepared in Example 3 was applied and cured in accordance with the following steps to form an coating layer:
• Step 1 A solvent borne ink composition were applied on tin plated steel sheet substrates by roll coating;
• Step 2 The coating composition prepared in Example 3 was wet-on- wet applied on the ink layer by roll coating in amounts of about 15 grams of the coating composition per square meter;
• Step 3 The coated substrate was then placed in an oven at a temperature of about 170 degrees Celsius for 15 minutes, to obtain a dried coating layer of about 9 grams per square meters.
• Coating Example 2 Application of a coating composition
• Example 4 The coating composition prepared in Example 4 was applied and cured in accordance with the steps described in Coating Example 1 except using the coating composition of Example 4 instead of the coating composition of Example 3 to form a coating layer.
• Viscosity Test A Ford cup #4 was used to test the viscosity at a temperature of 25 degrees Celsius. The cup was filled the coating composition of the present invention, and measure the time required for emptying the cup. The viscosity of the coating composition is desirably in the range of about 60s to about 160s.
• coated substrate plates prepared in Coating Examples 1 and 2, falling ball impact tester, 5% copper sulfate solution, and stopwatch;
• the falling ball impact tester was used to impact the coated substrate plates at a rate of lkg/50cm. After impact, the coated substrate plates were soaked in the copper sulphate solution soak for 2 minutes and then inspected for any corrosion areas.
• the 75 coated substrate plates were divided into three groups, 25 plates in each group.
• the mass of each plate was measured with an analytical balance to an accuracy of 0.1 mg, and the total mass of 25 plates in a group were calculated and recorded.
• a group of 25 plates was placed in the abrasion tester at the same time, rotated at a speed of 20 rep/min for 50 min.
• the group of 25 plates were taken out and the surfaces were cleaned with a soft brush to remove crumbles.
• the mass of each plates were again measured and the total mass of 25 plates in a group were calculated and recorded.
• the difference between the total mass before and after the abrasion was the abrasion value.
• the other two groups of 25 plates were tested following the same procedure.
• the average abrasion value of the three groups of coated substrate plates was the abrasion value for the coating. An abrasion value of less than 16 mg is desired.
• the coating composition of the present invention has appropriate viscosity, and high solid content which is desired in food and beverage package coating process.

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Citations (7)

• 2013
  • 2013-11-18 WO PCT/CN2013/087335 patent/WO2015070459A1/en active Application Filing
  • 2013-11-18 CN CN201380009934.5A patent/CN104169324B/zh not_active Expired - Fee Related
• 2015
  • 2015-01-23 HK HK15100741.5A patent/HK1200473A1/zh unknown

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