JP2006045542A - Coating for coating metal can cover, metal can cover coated with the coating and method for manufacturing them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating for coating a metal can cover which can easily form a coating film in a short time when it is applied on a metal can cover material, wherein the coating film hardly forms enamel hair when the cover is processed or opened, is more easily handled than conventional resin films, is thinner than laminated materials, and has properties such as processability, corrosion resistance, elution resistance and adhesiveness to metal plates, and to provide a method for manufacturing the same. <P>SOLUTION: The coating for coating a metal can cover comprises thermoplastic resin particles having an average primary particle size of 10-1,000 nm obtained by cooling a solution of the thermoplastic resin. The method for manufacturing a coating for coating a metal can cover comprises the steps of (a) dissolving a thermoplastic resin in an organic solvent to obtain a solution, (b) cooling the solution to obtain a suspension of particles of the thermoplastic resin having an average primary particle size of 10-1,000 nm, (c) separating the particles from the suspension and (d) dispersing the separated particles in a solvent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal can lid covering paint, a metal can lid coated with the paint, and a method for producing the same. Specifically, when applied to a metal can lid material, enamel hair is less likely to occur during lid forming and can opening, and is easier to handle than conventional resin films, compared to laminate materials. The present invention relates to a metal can lid coating and a method for producing the same, which can easily form a coating film having a thin film and having processability, corrosion resistance, dissolution property, adhesion to a metal plate and the like in a short time. The present invention also relates to a metal can lid coated with the paint and a method for producing the same.

  2. Description of the Related Art Conventionally, the surface of a can lid used for a metal container such as a food can or a beverage can for storing food has been generally painted or printed in order to impart corrosion resistance, decorativeness, and the like. As the paint, an epoxy thermosetting resin paint or a phenol thermosetting resin paint produced using bisphenol A as a phenol component has been used. In these paints, a small amount of bisphenol A is said to elute into the canned liquid from the coating film obtained by drying and curing the paint during canned storage, and bisphenol A is an environmental hormone substance, which is a problem. It was. In addition, since the coating film made of the paint is obtained by adding a curing agent to a low molecular weight resin and crosslinking it, an unreacted low molecular weight component may remain in the coating film. There was a problem that the molecular weight component adsorbs the taste and scent components of the canned content liquid and impairs the flavor of the canned content liquid.

  In order to solve such problems, paints made of thermoplastic resins such as polyester resins and polyolefin resins have been developed. For example, Patent Document 1 discloses that at least an inner surface side of a metal plate is covered with a thermoplastic resin film such as a polyolefin resin via an epoxy, polyester, or urethane adhesive. However, in this method, since it is necessary to form two layers of an adhesive layer and a thermoplastic resin film layer, labor and manufacturing cost are required, which is not economical. Furthermore, when the can body is double-rolled onto the can body after molding, the can lid is processed into a shape along a processing tool called a seaming roll (winding roll), but with a film made of a thermoplastic resin as described above, The surface of the can lid (outer side film surface) during this processing is subjected to the peeling (peeling) action by contacting the surface of the processing tool, and the film on the surface of the tightening part is scraped off, resulting in a problem of rust resistance. Not only occurs, but also has a problem that the appearance is unsightly.

  Further, as a method for solving the above problem, Patent Document 2 discloses that a thermoplastic resin film layer having an amorphization rate of 60% or more is provided on the outer surface of the can lid, and the metal surface side is low on the inner surface of the can lid. There is disclosed a method of providing a thermoplastic film layer having a biaxially oriented two-layer structure which is made of a resin having a melting point and a side having a high melting point on the side away from the metal surface. In this method, surface scraping or the like does not occur in the can lid manufacturing process, but the film thickness is as thick as about 10 μm, and it is not sufficiently satisfactory not only in the physical properties of the coating film but also economically.

  In addition, when a laminate material to which an oriented polyester resin film is bonded is used, hair-like (skin-like) resin strips called enamel hair (angel hair) are generated during lid forming and can opening. There was a bug. This is because the strength of the polyester resin film is high and the film is thick, and as a method for suppressing the generation of enamel hair, a method such as lowering the draw ratio at the time of resin film preparation has been tried, but technically It was difficult.

Japanese Patent Laid-Open No. 48-49589 JP 2002-193256 A

  Therefore, the present invention, when applied to a metal can lid material, enamel hair is less likely to occur during the molding and opening of the lid, is easier to handle than conventional resin films, laminate material Compared to the above, there are provided a metal can lid covering coating material and a method for producing the same, which can easily form a coating film having a thin film and having processability, corrosion resistance, dissolution property, adhesion to a metal plate and the like in a short time.

  That is, the present invention relates to a metal can lid coating composition containing particles of the thermoplastic resin having an average primary particle diameter of 10 to 1000 nm obtained by cooling a solution of the thermoplastic resin.

  It is preferable that the metal can lid coating paint further contains a thermosetting resin.

  The present invention also relates to a method for producing a metal can lid coating, comprising: (a) a step of obtaining a solution in which a thermoplastic resin is dissolved in an organic solvent; and (b) an average primary particle by cooling the solution. A step of obtaining a suspension of particles of the thermoplastic resin having a diameter of 10 to 1000 nm, (c) a step of separating the particles from the suspension, and (d) a step of dispersing the separated particles in a solvent. It relates to a manufacturing method.

  It is preferable that the manufacturing method further includes a step (e) of adding a thermosetting resin to the paint obtained in the step (d).

  Furthermore, this invention relates to the metal can lid which apply | coated the said metal can lid coating material.

  The present invention is also a method for producing the metal can lid, wherein (f) a step of applying the metal can lid covering paint to a metal plate, and (g) heating the applied paint to form particles The present invention relates to a production method comprising a step of melting the slag.

  The thermoplastic resin contained in the metal can cover coating paint of the present invention is a thermoplastic resin particle that is inherently difficult to dissolve in an organic solvent at room temperature, has high viscosity even if dissolved, and cannot be directly converted into a paint, By cooling the solution of the thermoplastic resin, the average primary particle size can be adjusted to 10 to 1000 nm, so that the physical properties of the coating film are affected like particles obtained by using various known polymerization reactions. Particles obtained without using a polymerization initiator, an emulsifier, a dispersant and the like. Therefore, the coating material for covering a metal can lid of the present invention containing particles of the thermoplastic resin is less likely to generate enamel hair when the lid is molded or opened when applied to a metal can lid material. It is easy to handle compared to conventional resin films, and it can be easily formed in a short time with a thin film compared to a laminate, which has processability, corrosion resistance, elution, and adhesion to a metal plate. Can do.

  The metal can lid coating paint of the present invention includes particles of the thermoplastic resin having an average primary particle diameter of 10 to 1000 nm obtained by cooling a solution of the thermoplastic resin.

  The metal material to be applied with the metal can lid covering paint of the present invention may be any metal plate used as a normal can-making material, for example, aluminum, steel, copper, stainless steel plate, and These are surface-treated metal plates such as ultra-thin tin-plated steel plates, tin-plated steel plates (tinplate), nickel-plated steel plates, galvanized steel plates, electrolytic chromic acid-treated steel plates (tin-free steel), chrome-plated steel plates, aluminum-plated steel plates, Examples thereof include a phosphoric acid-treated steel plate, an aluminum plate, and an aluminum alloy plate, but the present invention is not limited to such examples. The metal-plated steel sheet is preferably subjected to surface treatment from the viewpoint of corrosion resistance and adhesion to a thermoplastic resin, such as chromate treatment, phosphoric acid treatment, and organic-inorganic composite treatment.

  Furthermore, clad materials can be used regardless of the type, such as two-layer clad, partial clad, multi-layer clad, and fully clad clad, such as nickel / stainless steel clad material, monel / stainless steel clad material, copper / stainless steel clad material, Stainless steel / iron / stainless steel clad, tantalum / copper / stainless steel clad, titanium / stainless steel / nickel clad, aluminum / stainless steel clad, iron / copper clad, aluminum / niobium clad, aluminum / titanium / Stainless steel cladding material, copper / aluminum cladding material, copper / nickel cladding material, nickel / iron cladding material, and the like.

  In general, the plate thickness is preferably 0.20 to 0.50 mm, more preferably 0.23 to 0.30 mm.

  As thermoplastic resins, aromatic polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; polylactic acid, polyglycolic acid, polyethylene alkanoate, polybutylene alkanoate, polyhydroxyalkanoate And aliphatic polyester resins such as polycaprolactone; polyamide resins such as nylon 6, nylon 6,6, nylon 12, and MXD6 nylon; and polycarbonate resins. Of these, polyethylene terephthalate and polybutylene terephthalate are preferable in terms of barrier properties, transparency, physical properties, and safety. In addition, as the thermoplastic resin, a recycled resin typified by recycled PET resin or the like can be used, and it may be crystalline or non-crystalline. However, it is not limited to these.

  As the aromatic polyester resin, those obtained by copolymerizing 1 to 15 mol% of isophthalic acid are preferable in view of excellent physical properties such as processability.

  Solvents for dissolving the thermoplastic resin include ester solvents such as ethyl acetate, butyl acetate, propylene carbonate and 4-butyrolactone, dibasic acid ester solvents such as dimethyl adipate, dimethyl glutarate and dimethyl succinate, cyclohexanone, Ketone solvents such as isophorone and methyl isobutyl ketone, hydrocarbon solvents such as cyclohexane, toluene and xylene, alcohol solvents such as benzyl alcohol and cyclohexanol, ethylene glycol monobutyl ether, dipropylene glycol butyl ether, 2- (2-methoxy Ether solvents such as ethoxy) ethanol and bis (2-methoxyethyl) ether, amide solvents such as formamide, dimethylformamide and dimethylacetamide, N-methyl-2-pyro Although pyrrolidone solvent and water and mixtures thereof, such as Don and the like, but is not limited thereto. In particular, the liquid after separating the particles from the obtained suspension can be used repeatedly as a solvent for further dissolving the thermoplastic resin. Mixed ester solvent consisting of dimethyl, dimethyl glutarate and dimethyl succinate, dimethylacetamide, propylene carbonate, 4-butyrolactone, 2- (2-methoxyethoxy) ethanol, when nylon is used as the thermoplastic resin, benzyl alcohol , Dimethylacetamide and N-methyl-2-pyrrolidone are preferred.

  It is preferable that the temperature of the solvent at the time of melt | dissolving a thermoplastic resin is 70-200 degreeC. When the thermoplastic resin is polyethylene terephthalate or polybutylene terephthalate, the temperature is more preferably 130 to 190 ° C, and further preferably 140 to 185 ° C. When a thermoplastic resin is polylactic acid, it is more preferable that it is 70-150 degreeC, and it is further more preferable that it is 100-140 degreeC. When a thermoplastic resin is polyglycolic acid, 130-170 degreeC is preferable and 140-160 degreeC is more preferable. When a thermoplastic resin is MXD6 nylon, it is more preferable that it is 130-180 degreeC, and it is further more preferable that it is 150-170 degreeC. Moreover, when a thermoplastic resin is nylon 6, it is more preferable that it is 120-180 degreeC, and it is further more preferable that it is 130-170 degreeC. When the thermoplastic resin is nylon 6,6, the temperature is more preferably 150 to 190 ° C, and further preferably 170 to 180 ° C. When the thermoplastic resin is nylon 12, it is more preferably 120 to 150 ° C, and further preferably 130 to 140 ° C. When the thermoplastic resin is polycarbonate, it is more preferably 130 to 180 ° C, and further preferably 140 to 170 ° C. If the temperature of the solvent is less than 70 ° C., the thermoplastic resin does not dissolve, so there is a tendency that desired particles having an average primary particle diameter of 1000 nm or less are not obtained. If the temperature exceeds 200 ° C., the thermoplastic resin or the solvent There is a tendency to decompose and turn yellow.

  The blending amount of the thermoplastic resin in the solvent is preferably 1 to 30 parts by weight, more preferably 1 to 20 parts by weight, and still more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the solvent. If the blending amount is less than 1 part by weight, there is a problem in terms of productivity. Moreover, when it exceeds 30 weight part, there exists a tendency for it to become difficult to obtain the particle | grains with a target average primary particle diameter of 1000 nm or less.

  As a means for cooling the thermoplastic resin solution, a cooling device such as a heat exchanger can be cited. The cooling means is preferably used to cool the thermoplastic resin solution at 70 to 200 ° C. to 50 ° C. or lower, more preferably 45 ° C. or lower. When the temperature of the solution after cooling exceeds 50 ° C., both the primary particle diameter and the secondary particle diameter of the obtained particles tend to increase.

  As a cooling method, a thermoplastic resin solution itself is cooled using a heat exchanger, and a solvent cooled to 20 to -90 ° C using a heat exchanger is mixed with the thermoplastic resin solution. The method of cooling is raised by doing. From the viewpoint of cooling efficiency, a method of mixing with a cooled solvent is preferable.

  The cooling rate is preferably 20 ° C./s or more, more preferably 50 ° C./s or more, and further preferably 100 ° C./s or more. There exists a tendency for the primary particle diameter of the particle | grains obtained to be less than 20 degrees C / s to exceed 1000 nm.

  The average primary particle diameter of the thermoplastic resin particles obtained by cooling is 10 to 1000 nm, preferably 10 to 800 nm, more preferably 30 to 500 nm, and still more preferably 50 to 300 nm. When the average primary particle diameter exceeds 1000 nm, there is a tendency that the film thickness of the coating film becomes large or that when it is made into a thin film, it does not become a continuous film. On the other hand, when the average primary particle size is smaller than 10 nm, the viscosity of the obtained suspension tends to be high and the separation operation tends to be difficult.

  The average secondary particle diameter of the particles is preferably 30 μm or less, and more preferably 1 to 10 μm. When the average secondary particle diameter exceeds 30 μm, the film thickness tends to increase when applied, and the desired coating film tends not to be obtained.

  Here, the primary particles refer to particles that cannot be dispersed any more. Secondary particles refer to particles in which primary particles are aggregated.

  Examples of a method for separating particles from a suspension containing particles include filtration and centrifugation, but are not limited thereto. Examples of the filter for filtering include a ceramic filter.

  Moreover, it is preferable to dry the particles after separating the particles. The drying method is not particularly limited, such as vacuum drying, natural drying, drying with a dryer or oven. However, when drying with a dryer or oven, it is necessary to set the temperature so that the particles do not melt.

  The metal can lid coating paint of the present invention is made of thermoplastic resin particles having an average primary particle size of 10 to 1000 nm. However, it may be composed of a mixture of the thermoplastic resin particles, or an additive such as a curing agent or a thermosetting resin may be added to the thermoplastic resin particles. Especially, it is preferable to add a thermosetting resin at the point which can form the coating film excellent with the adhesiveness of a coating film, scratch resistance, and the fracture | rupture property of a coating film.

  Examples of the thermosetting resin include unsaturated polyester resins, acrylic resins, epoxy resins, urethane resins, melamine resins, phenol resins, urea resins, etc. A resin is preferred.

  As addition amount of a thermosetting resin, 1-20 weight part is preferable with respect to 100 weight part of thermoplastic resin particles, and 5-15 weight part is more preferable. If the blending amount is less than 1 part by weight, there is a tendency that sufficient effects cannot be obtained for scratch resistance and ruptureability of the coating film, and if it exceeds 20 parts by weight, physical properties such as workability tend to decrease. .

  Further, the thermoplastic resin particles may be used by adding to other paints. The method of adding the thermoplastic resin particles to other paints is preferable because a tougher coating film can be formed.

  The paint is not particularly limited as long as it is generally used as a paint, but it is a thermoset made of polyester resin, acrylic resin, epoxy resin, urethane resin, melamine resin, phenol resin, urea resin, or the like. Mold paints.

  Solvents for dispersing the obtained particles include ester solvents such as ethyl acetate, butyl acetate, propylene carbonate and 4-butyrolactone, dibasic acid ester solvents such as dimethyl adipate, dimethyl glutarate and dimethyl succinate, cyclohexanone , Ketone solvents such as isophorone and methyl isobutyl ketone, hydrocarbon solvents such as cyclohexane, toluene and xylene, alcohol solvents such as benzyl alcohol and cyclohexanol, ethylene glycol monobutyl ether, dipropylene glycol butyl ether, 2- (2- Ether solvents such as methoxyethoxy) ethanol and bis (2-methoxyethyl) ether, amide solvents such as formamide, dimethylformamide and dimethylacetamide, N-methyl-2-pyro Pyrrolidone-based solvent and water and mixtures thereof, such as Don and the like, but is not limited thereto, it is possible to use any solvent suitable for paint seeking.

  When the thermoplastic resin is polyethylene terephthalate, a mixed solvent of cyclohexanone and xylene, dimethylacetamide, dimethyl adipate, dimethyl glutarate and dimethyl succinate, propylene carbonate, 4-butyrolactone, 2- (2 -Methoxyethoxy) ethanol, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, ethyl acetate, water are preferred, and when the thermoplastic resin is MXD6 nylon, dimethylacetamide is preferred, and when the thermoplastic resin is nylon 12, Dimethylacetamide and benzyl alcohol are preferred. When the thermoplastic resin is nylon 6,6, benzyl alcohol is preferred. When the thermoplastic resin is nylon 6, Tylacetamide and benzyl alcohol are preferred. When the thermoplastic resin is polylactic acid, dimethylacetamide, butyl acetate, dimethyl succinate, and methyl isobutyl ketone are preferred. When the thermoplastic resin is polyglycolic acid, bis (2 -Methoxyethyl) ether is preferred, and when the thermoplastic resin is polycarbonate, a mixed ester solvent comprising dimethylacetamide, cyclohexanone, dimethyl adipate, dimethyl glutarate and dimethyl succinate is preferred. When dispersing, a commonly used dispersant may be used. The amount of the dispersant used is not particularly limited, and can be used as long as the desired performance of the coating film is not impaired.

  If necessary, for example, acid catalysts such as sulfonic acids such as p-toluenesulfonic acid and dodecylbenzenesulfonic acid, phosphoric acids such as alkylphosphoric acid, curing aids such as amine block of the acid catalyst, leveling agents, Additives such as antifoaming agents and lubricants, and coloring agents such as pigments may be blended.

  The addition amount of the thermoplastic resin particles is preferably 5% by weight or more, more preferably 10% by weight or more, further preferably 15% by weight or more, based on the total resin contained in the paint. It is particularly preferable that the amount be at least% by weight. When the added amount of the thermoplastic resin is less than 5% by weight, pinholes tend to be generated in the obtained coating film.

  Further, the ratio of the thermoplastic resin particles and the solvent is not particularly limited, and may be appropriately adjusted according to the desired coating film.

  Examples of the method for dispersing the thermoplastic resin particles include dispersion using ultrasonic waves and dispersion using a stirrer. Examples thereof include a homogenizer, a homomixer, a roll mill, a bead mill, and a high-pressure wet pulverization apparatus.

  When secondary particles are dispersed in a solvent, it is preferable to select a solvent and a dispersion method to atomize, and it is more preferable to finally make primary particles. By atomizing, it becomes possible to control the coating thickness to a desired thickness, and it is possible to finish a smoother coating.

  The paint of the present invention can be applied by a known method such as a roll coating method, a spray coating method, a brush coating method, a spatula coating method, a dip coating method, an electrodeposition coating method, or an electrostatic coating method.

Paint coating amount in the case of forming a coating film using the coating composition of the present invention, the weight after drying the paint is a 0.1 to 50 g / m ^2, preferably from 1 to 50 g / m ^2, More preferably, it is adjusted to be 3 to 10 g / m ² .

  The coating film is formed from the paint of the present invention by applying the paint, evaporating the solvent by heating, and then melting the particles. Thereby, there is no pinhole, a uniform coating film is formed, and a coating film excellent in solvent resistance and the like is obtained.

  The heating temperature is preferably from 100 to 300 ° C, more preferably from 150 to 280 ° C. Further, the heating time is preferably 10 to 60 seconds, and more preferably 15 to 30 seconds. Furthermore, it is preferable to cool with water after heating. This is because water-cooling further improves various physical properties such as the appearance and workability of the coating film.

  The metal can lid of the present invention can be obtained by molding using a metal plate coated with the paint of the present invention. It can also be obtained by coating an unpainted can lid with the paint of the present invention. The manufacturing method and shape of the metal can lid may be any method and shape used for general can lids, and are not particularly limited. Examples of the metal can lid include lids and seals of beverage cans, food cans, art cans, aerosol cans, 18L cans, dry battery outer cans, battery cans, and the like.

  When applied to a metal can lid material, the paint of the present invention is less susceptible to enamel hair during lid forming and opening, and is easier to handle than conventional resin films. It is a metal can lid coating material that can be easily formed in a short time with a thin film compared to the material and having processability, corrosion resistance, dissolution property, adhesion to a metal plate, and the like.

  Next, the paint of the present invention will be described based on examples, but the present invention is not limited thereto.

<Average primary particle size>
The measurement was performed using a scanning electron microscope (JEM-6301F, manufactured by JEOL Ltd.) and a dynamic light scattering particle size distribution measuring device (LB-550, manufactured by Horiba, Ltd.).

<Film thickness>
Measurement was performed using an electromagnetic induction / overcurrent film thickness meter (LZ-200W, manufactured by Kett Scientific Laboratory).

<Rivet workability>
The state when the coated plate was rivet-hole processed was visually observed and evaluated based on the following evaluation criteria.
A: No peeling at all.
B: Partial peeling is observed.
C: Peeling is observed as a whole.

<Adhesion>
In accordance with the method described in JIS K-5400 (1990), the painted plate after baking was cut with 1 mm intervals so as to penetrate the coating film and reach the substrate with a cutter knife, and 100 grids (10 × 10). Nichiban Co., Ltd. cello tape (registered trademark) is completely adhered to this, and it peels off suddenly in the direction of 90 ° with respect to the coating surface, visually observes the state of the coating film, and based on the following evaluation criteria evaluated.
A: No peeling at all.
B: 1 to 5 squares are peeled off.
C: Six or more cells are peeled off.

<Energization amount>
The baked coated plate 100 cm ² is immersed in 1% saline containing 0.3% of a surfactant, a voltage of 6 V is applied, and the energization amount after 4 seconds is displayed in milliamperes (mA). The smaller this value, the fewer the coating film defects and the better the coating.

<Appearance of tightening part>
After the coated and manufactured can lid was wound around the welded can body, the tightened portion was visually evaluated.
A: The shaving of the coating film is not seen.
B: The coating film is partially cut away.
C: The coating film is scraped as a whole.

<Corrosion resistance>
Painted and manufactured can lids were packed with 5% mixed solutions of malic acid, citric acid and salt, stored in a constant temperature bath at 55 ° C. for 4 days with the lid down, and the degree of corrosion was visually evaluated. .
A: No discoloration is seen at all.
B: A faint discoloration is observed.
C: Strong discoloration is observed.

<Total organic carbon content>
Coated plate subjected to 130 ° C. × 30 minutes retort extracted with distilled water 600cc against 600 cm ^2, total organic carbon meter (TOC-V CHS / CSN, manufactured by Shimadzu Corporation) total organic carbon eluted amount using the (TOC elution amount) was measured.

<Enamel hair>
Using the metal plates obtained in Examples 1 to 4, the occurrence rate of enamel hair when 100 can lids were produced with a can lid punching machine (manufactured by Kato Kiko Co., Ltd.) was visually evaluated.

Production Example 1 (Production of polyethylene terephthalate resin particles)
30 g of polyethylene terephthalate (MA-1340P, manufactured by Unitika Co., Ltd.) obtained by copolymerizing 8 mol% of isophthalic acid as a thermoplastic resin in a 1 L four-necked flask equipped with a thermometer and a stirrer, and adipine as a solvent 570 g of a mixture of dimethyl acid, dimethyl glutarate, and dimethyl succinate (DBE (registered trademark), manufactured by DuPont) was weighed. Thereafter, the temperature of the liquid was adjusted to 180 ° C. while ventilating nitrogen, and the thermoplastic resin was dissolved in the solvent. The obtained solution was mixed with a DBE solvent cooled to −35 ° C. by a heat exchanger (manufactured by M Technique Co., Ltd.) to obtain a suspension containing thermoplastic resin particles. The temperature of the suspension after 1 second from the time of mixing was 45 ° C.

  Particles were separated from the obtained suspension using a sharp press centrifuge (manufactured by Sakai Kogyo Co., Ltd.) to obtain a filter cake. The obtained cake had a solvent content of 75%.

  Moreover, from the SEM image (FIG. 1) and particle size distribution (FIG. 2) of the obtained particles, the average primary particle size was 200 nm or less.

Production Example 2 (Production of polybutylene terephthalate resin particles)
Polybutylene terephthalate (Novaduran 5008, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) is used as the thermoplastic resin, and dimethylacetamide (Mitsubishi Gas Chemical Co., Ltd.) is used as the solvent. The melting temperature is 160 ° C. and the cooling temperature is −20 ° C. As a result, a suspension containing thermoplastic resin particles was obtained in the same manner as in Production Example 1. The temperature of the suspension after 1 second from the time of mixing was 45 ° C.

  Similar to Production Example 1, particles were separated from the obtained suspension using a sharp press centrifuge to obtain a filter cake. The obtained cake had a solvent content of 90%.

  Moreover, from the obtained particle size distribution (FIG. 3), the average primary particle size was 200 nm or less.

Production Example 3 (Production of polylactic acid resin particles)
Using a polylactic acid as a thermoplastic resin, DBE as a solvent, a dissolution temperature of 140 ° C., a cooling temperature of −35 ° C., and a suspension containing thermoplastic resin particles in the same manner as in Production Example 1, and A filter cake was obtained.

  The obtained cake had a solvent content of 71%. Moreover, the average primary particle diameter of the obtained particles was 250 nm or less from the particle size distribution (FIG. 4).

Production Example 4 (Production of polyglycolic acid resin particles)
Using Polyglycolic acid (PGA-P Mitsui Chemical Co., Ltd.) as the thermoplastic resin, bis (2-methoxyethyl) ether as the solvent, the dissolution temperature being 150 ° C., and the cooling temperature being −35 ° C. As a result, a suspension and a filter cake containing thermoplastic resin particles were obtained.

  The obtained cake had a solvent content of 73%. Moreover, the average primary particle diameter of the obtained particles was 150 nm or less from the particle size distribution (FIG. 5).

Production Example 5 (Production of MXD6 nylon resin particles)
MXD6 nylon (metaxylylenediamine adipamide, 6007, manufactured by Mitsubishi Gas Chemical Co., Ltd.) as the thermoplastic resin, dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as the solvent, a melting temperature of 160 ° C., and a cooling temperature of A suspension and a filter cake containing thermoplastic resin particles were obtained at −20 ° C. in the same manner as in Production Example 1.

  The obtained cake had a solvent content of 80%. Moreover, the average primary particle diameter of the obtained particles was 350 nm or less from the particle size distribution (FIG. 6).

Production Example 6 (Production of nylon 6 resin particles)
Nylon 6 (Novamid 1010J, manufactured by Mitsubishi Engineering Plastics) is used as the thermoplastic resin, N-methyl-2-pyrrolidone (manufactured by Mitsubishi Chemical Corporation) is used as the solvent, the dissolution temperature is 170 ° C., and the cooling temperature is −20 ° C. As a result, a suspension containing thermoplastic resin particles and a filter cake were obtained in the same manner as in Production Example 1.

  The obtained cake had a solvent content of 79%. Moreover, the average primary particle diameter of the obtained particles was 350 nm or less from the particle size distribution (FIG. 7).

Production Example 7 (Production of nylon 6,6 resin particles)
Nylon 6,6 (Novamid 3010, manufactured by Mitsubishi Engineering Plastics) as a thermoplastic resin, benzyl alcohol (manufactured by Tohoku Tohso Chemical Co., Ltd.) as a solvent, a melting temperature of 170 ° C., and a cooling temperature of −15 ° C. By the same operation as in Production Example 1, a suspension containing thermoplastic resin particles and a filter cake were obtained.

  The obtained cake had a solvent content of 77%. Moreover, the average primary particle diameter of the obtained particles was 200 nm or less from the particle size distribution (FIG. 8).

Production Example 8 (Production of polycarbonate resin particles)
By using polycarbonate (Iupilon S-2000R, manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a thermoplastic resin, DBE as a solvent, a dissolution temperature of 170 ° C., a cooling temperature of −20 ° C., and the same operation as in Production Example 1, A suspension and a filter cake containing plastic resin particles were obtained.

  The obtained cake had a solvent content of 64%. Moreover, the average primary particle diameter of the obtained particles was 300 nm or less from the particle size distribution (FIG. 9).

Example 1
150.0 g of polyethylene terephthalate resin cake obtained in Production Example 1 and carnauba wax dispersion (SL506 (dispersion in dipropylene glycol-n-monobutyl ether, solid content 18.5%) manufactured by San Nopco Co., Ltd.) 2.0 g , DBE 98.0g and 2mmφ glass beads 125.0g were weighed into a 450ml mayonnaise bottle, well closed, then dispersed for 2 hours with a paint shaker (manufactured by Asada Steel Corporation), and separated from the glass beads using gauze. A metal coating was obtained. The obtained coating material had a solid content of 15.0% and a viscosity of 44 seconds (Ford Cup No. 4).

The resulting coating is applied to the inner and outer surfaces of an aluminum plate (A5182, phosphate chromate (CP) treated, plate thickness 0.300 mm, manufactured by Sumitomo Light Metal Industries, Ltd.) using a bar coater, and the film thickness after drying is 3 μm. The coating was performed in such a manner (coating amount after drying: 4.2 g / m ² ), and the mixture was placed in a hot air circulation oven (manufactured by Shoei Seisakusho Co., Ltd.) set at 260 ° C. and a wind speed of 20 m / second, and then cooled with water.

  The results of the performance test of the obtained coating film are shown in Table 1 (inner surface side) and Table 2 (outer surface side). Regarding the results of the performance tests of the coating films obtained in the following examples, Table 1 shows the results on the inner surface side and Table 2 shows the results on the outer surface side.

Example 2
200.0 g of polybutylene terephthalate resin cake obtained in Production Example 2, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol-n-monobutyl ether, solid content 18.5%) manufactured by San Nopco Co., Ltd.) Weigh 1 g, 48.9 g of dimethylacetamide and 125.0 g of 2 mmφ glass beads in a 450 ml mayonnaise bottle, close the lid well, and disperse with a paint shaker (manufactured by Asada Steel Corporation) for 2 hours. To obtain a coating material for metal coating. The obtained coating material had a solid content of 8.0% and a viscosity of 58 seconds (Ford Cup No. 4).

The resulting coating is applied to the inner and outer surfaces of an aluminum plate (A5182, phosphate chromate (CP) treated, plate thickness 0.300 mm, manufactured by Sumitomo Light Metal Industries, Ltd.) using a bar coater, and the film thickness after drying is 3 μm. The coating was performed in such a manner (coating amount after drying: 3.9 g / m ² ), put in a hot air circulation oven (manufactured by Shoei Seisakusho Co., Ltd.) set at 260 ° C. and a wind speed of 20 m / second, and then cooled with water.

  The results of the performance test of the obtained coating film are shown in Tables 1 and 2.

Example 3
As a coating on the inner surface side, 60.8 g of epoxy resin (Epicoat 1009 made by Japan Epoxy Resin Co., Ltd.) 60.8 g of ethylene glycol monobutyl ether, 43.6 g of Swazol 1000, in a 500 ml four-necked flask equipped with a thermometer and a stirrer, Hard lanolin (manufactured by Nippon Seika Co., Ltd.) dissolved in propylene glycol monomethyl acetate 20.6 g at 130-140 ° C. and dissolved in diethylene glycol monobutyl ether 72.7 g, arcosolv PM 14.2 g, methyl isobutyl ketone 27.0 g 5 g was added, and 6.4 g of a phenol resin (Hitanol 4010 butanol solution, solid content 50%, manufactured by Hitachi Chemical Polymer Co., Ltd.) and 5.2 g of ethylene glycol monobutyl ether were added. After stirring, a paint was obtained. The obtained coating material had a solid content of 24.0% and a viscosity of 30 seconds (Ford Cup No. 4).

The resulting coating is applied to the inner surface of an aluminum plate (A5182, phosphoric acid chromate (CP) treated, plate thickness 0.300 mm, manufactured by Sumitomo Light Metal Industries, Ltd.) using a bar coater, and the film thickness after drying is 3 μm. (Applied amount after drying: 3.3 g / m ² ), put in a hot air circulation oven (manufactured by Shoei Seisakusho Co., Ltd.) set at 260 ° C. and a wind speed of 20 m / second for 20 seconds, and the inner surface side is coated with resin An aluminum plate was obtained. The obtained inner surface-coated aluminum plate was used for outer surface side coating in Examples 4 to 8 including Example 3.

  155.2 g of polylactic acid resin cake obtained in Production Example 3 as a coating on the outer surface, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol mono-n-butyl ether, solid content 18.5%) San Nopco stock 2.4g, 92.4g of DBE, and 125.0g of 2mmφ glass beads were weighed into a 450ml mayonnaise bottle, well closed, and then dispersed in a paint shaker for 2 hours. Separately, a paint for metal coating was obtained. The obtained coating material had a solid content of 18.0% and a viscosity of 40 seconds (Ford Cup No. 4).

Using a bar coater, the obtained paint was applied to the outer surface side of the inner surface coated aluminum plate so that the film thickness after drying was 3 μm (coating amount after drying: 3.9 g / m ² ), 200 ° C., It put into the hot air circulation type oven (made by Shoei Seisakusho Co., Ltd.) set to the wind speed of 20 m / sec for 20 seconds, and then water-cooled.

  The results of the performance test of the obtained coating film are shown in Table 2.

Example 4
1. 162.0 g of polyglycolic acid resin cake obtained in Production Example 4, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol mono-n-butyl ether, solid content 18.5%) manufactured by San Nopco Co., Ltd.) Weigh 4 g, 85.6 g of bis (2-methoxyethyl) ether, and 125.0 g of 2 mmφ glass beads in a 450 ml mayonnaise bottle, close well, disperse with a paint shaker for 2 hours, and use glass beads with gauze. To obtain a coating material for metal coating. The obtained coating material had a solid content of 17.5% and a viscosity of 43 seconds (Ford Cup No. 4).

In the same manner as in Example 3, the obtained paint was applied to the outer surface side of the inner surface-coated aluminum plate of Example 3 using a bar coater so that the film thickness after drying was 3 μm (coating amount after drying: 4 8 g / m ² ), 230 ° C., and hot air circulation oven set at 20 m / sec (20 m / sec), and then cooled in water for 20 seconds.

  The results of the performance test of the obtained coating film are shown in Table 2.

Example 5
MXD6 nylon resin cake 175.0 g obtained in Production Example 5, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol mono-n-butyl ether, solid content 18.5%) manufactured by San Nopco Co., Ltd.) 1.9 g , 73.1 g of dimethylacetamide, and 125.0 g of 2 mmφ glass beads were weighed into a 450 ml mayonnaise bottle, well closed, then dispersed in a paint shaker for 2 hours, separated from the glass beads using gauze, and coated for metal coating Got. The obtained coating material had a solid content of 14.0% and a viscosity of 50 seconds (Ford Cup No. 4).

In the same manner as in Example 3, the obtained paint was applied to the outer surface side of the inner surface-coated aluminum plate of Example 3 using a bar coater so that the film thickness after drying was 3 μm (coating amount after drying: 3 6 g / m ² ), 260 ° C., and a wind speed of 20 m / sec.

  The results of the performance test of the obtained coating film are shown in Table 2.

Example 6
Nylon 6 resin cake 166.7 g obtained in Production Example 6, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol mono-n-butyl ether, solid content 18.5%) manufactured by San Nopco Co., Ltd.) 1.9 g Weigh 81.4 g of N-methyl-2-pyrrolidone and 125.0 g of 2 mmφ glass beads in a 450 ml mayonnaise bottle, close well, disperse in a paint shaker for 2 hours, filter with glass beads using gauze. Separately, a paint for metal coating was obtained. The obtained coating material had a solid content of 14.0% and a viscosity of 54 seconds (Ford Cup No. 4).

In the same manner as in Example 3, the obtained paint was applied to the outer surface side of the inner surface-coated aluminum plate of Example 3 using a bar coater so that the film thickness after drying was 3 μm (coating amount after drying: 3 4 g / m ² ), 250 ° C., and hot air circulation oven (made by Shoei Seisakusho Co., Ltd.) set at 20 m / sec.

  The results of the performance test of the obtained coating film are shown in Table 2.

Example 7
157.6 g of nylon 6,6 resin cake obtained in Production Example 7, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol mono-n-butyl ether, solid content 18.5%) manufactured by San Nopco) 2 0.0 g, 90.4 g of benzyl alcohol, and 125.0 g of 2 mmφ glass beads were weighed into a 450 ml mayonnaise bottle, well closed, then dispersed in a paint shaker for 2 hours, separated from the glass beads with gauze and coated with metal A paint was obtained. The obtained coating material had a solid content of 14.5% and a viscosity of 58 seconds (Ford Cup No. 4).

In the same manner as in Example 3, the obtained paint was applied to the outer surface side of the inner surface-coated aluminum plate of Example 3 using a bar coater so that the film thickness after drying was 3 μm (coating amount after drying: 3 .4 g / m ² ) was placed in a hot air circulation oven (manufactured by Shoei Seisakusho Co., Ltd.) set at 280 ° C. and a wind speed of 20 m / sec for 20 seconds, and then cooled with water.

  The results of the performance test of the obtained coating film are shown in Table 2.

Example 8
156.3 g of polycarbonate resin cake obtained in Production Example 8, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol mono-n-butyl ether, solid content 18.5%) manufactured by San Nopco Co., Ltd.), 3.0 g, Weigh 90.7g of DBE and 125.0g of 2mmφ glass beads in a 450ml mayonnaise bottle, close the lid well, disperse with a paint shaker for 2 hours, and filter with glass beads using gauze to obtain a metal coating paint. It was. The obtained coating material had a solid content of 22.5% and a viscosity of 60 seconds (Ford Cup No. 4).

In the same manner as in Example 3, the obtained paint was applied to the outer surface side of the inner surface-coated aluminum plate of Example 3 using a bar coater so that the film thickness after drying was 3 μm (coating amount after drying: 3 0.6 g / m ² ), 250 ° C., and hot air circulation oven (made by Shoei Seisakusho Co., Ltd.) set at a wind speed of 20 m / sec.

  The results of the performance test of the obtained coating film are shown in Table 2.

Example 9
135.0 g of polyethylene terephthalate resin cake obtained in Production Example 1 and carnauba wax dispersion (SL506 (dispersion in dipropylene glycol-n-monobutyl ether, solid content 18.5%) manufactured by San Nopco Co., Ltd.) 2.0 g After weighing 7.5 g of phenolic resin (Hitanol 4010 (butanol solution, solid content 50%) manufactured by Hitachi Chemical Co., Ltd.), 105.5 g of DBE and 125.0 g of 2 mmφ glass beads into a 450 ml mayonnaise bottle, the lid was well closed The mixture was dispersed with a paint shaker (manufactured by Asada Steel Corporation) for 2 hours, and separated from glass beads using gauze to obtain a coating material for metal coating. The obtained coating material had a solid content of 15.0% and a viscosity of 40 seconds (Ford Cup No. 4).

  A test plate was prepared in the same manner as in Example 1 using the obtained paint.

  The results of the performance test of the obtained coating film are shown in Tables 1 and 2.

Example 10
180.0 g of polybutylene terephthalate resin cake obtained in Production Example 2, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol-n-monobutyl ether, solid content 18.5%) manufactured by San Nopco Co., Ltd.) 1 g, phenolic resin (Hitanol 4010 (butanol solution, solid content 50%) manufactured by Hitachi Chemical Co., Ltd.) 4.0 g, 64.9 g of dimethylacetamide and 125.0 g of 2 mmφ glass beads are weighed into a 450 ml mayonnaise bottle and well covered. After closing, the mixture was dispersed with a paint shaker (manufactured by Asada Steel Corporation) for 2 hours, and separated from glass beads using gauze to obtain a coating material for metal coating. The obtained coating material had a solid content of 8.0% and a viscosity of 52 seconds (Ford Cup No. 4).

  A test plate was prepared in the same manner as in Example 2 using the obtained paint.

  The results of the performance test of the obtained coating film are shown in Tables 1 and 2.

Comparative Example 1
As a paint on the inner surface, 60.8 g of epoxy resin (Epicoat 1009 made by Japan Epoxy Resin Co., Ltd.) 60.8 g of ethylene glycol monobutyl ether, 43.6 g of Swazole 1000, propylene, in a 500 ml four-necked flask equipped with a thermometer and a stirrer Hard Lanolin (manufactured by Nippon Seika Co., Ltd.) 0.5 g dissolved in 20.6 g of glycol monomethyl acetate and dissolved in 72.7 g of diethylene glycol monobutyl ether, 14.2 g of Arcosolve PM, 27.0 g of methyl isobutyl ketone 6.4 g of a phenolic resin (Hitanol 4010 butanol solution, solid content 50%, manufactured by Hitachi Chemical Polymer Co., Ltd.) and 5.2 g of ethylene glycol mono-butyl ether were added, and a paint was obtained after stirring. The obtained coating material had a solid content of 24.0% and a viscosity of 30 seconds (Ford Cup No. 4).

  As an exterior coating, 261.3 g of polyester resin (Byron GK880 (cyclohexanone / xylene 1: 1 solution, solid content 30%) manufactured by Toyobo Co., Ltd.), melamine resin (Cymel 303, solid content 100%, Mitsui Cytec Co., Ltd.) 5.6 g, carnauba wax dispersion (SL506 (dispersion in dipropylene glycol mono-n-butyl ether, solid content 18.5%) manufactured by San Nopco) 1.1 g, cyclohexanone / xylene 1: 1 mixed solvent 89 .4 g was weighed into a 1 L stainless beaker and stirred for 10 minutes with a disper (Agitator manufactured by Asada Steel Corporation) to obtain a paint. The obtained coating material had a solid content of 23.5% and a viscosity of 25 seconds (Ford Cup No. 4).

The obtained paint is applied to an aluminum plate (A5182, phosphate chromate (CP) treated, plate thickness 0.300 mm, manufactured by Sumitomo Light Metal Industry Co., Ltd.) using a bar coater so that the film thickness after drying becomes 3 μm. It was painted (applied amount after drying: 3.3 g / m ² ), placed in a hot air circulation oven (manufactured by Shoei Seisakusho Co., Ltd.) set at 260 ° C. and a wind speed of 20 m / sec, and then air-cooled.

  The results of the performance test of the obtained coating film are shown in Tables 1 and 2.

Comparative Example 2
Biaxially stretched polyester film 11.5 μm (Lumirror S10 # 12 manufactured by Toray Industries, Inc.) on the inner and outer surfaces of an aluminum plate (A5182, plate thickness 0.300 mm, manufactured by Sumitomo Light Metal Industry Co., Ltd.), plate temperature 250 ° C., laminating roll temperature The laminate was heat-laminated at 160 ° C. and a plate passing speed of 30 m / min, and immediately cooled with water to obtain a resin-coated plate by lamination.

Tables 1 and 2 show the results of performance tests of the obtained coating films.
Comparative Example 2
Biaxially stretched polyester film 11.5 μm (Lumirror S10 # 12, manufactured by Toray Industries, Inc.) is heat-laminated at a plate temperature of 250 ° C., a laminating roll temperature of 160 ° C. and a plate-passing speed of 30 m / min, and immediately cooled with water to provide a resin coating by lamination. A steel plate was obtained.

2 is an SEM image (× 35000 times) of primary particles of a thermoplastic resin obtained in Production Example 1. FIG. 2 is a particle size distribution of thermoplastic resin particles obtained in Production Example 1. FIG. 3 is a particle size distribution of thermoplastic resin particles obtained in Production Example 2. FIG. 4 is a particle size distribution of thermoplastic resin particles obtained in Production Example 3. 4 is a particle size distribution of thermoplastic resin particles obtained in Production Example 4. 4 is a particle size distribution of thermoplastic resin particles obtained in Production Example 5. It is a particle size distribution of the thermoplastic resin particles obtained in Production Example 6. 4 is a particle size distribution of thermoplastic resin particles obtained in Production Example 7. 4 is a particle size distribution of thermoplastic resin particles obtained in Production Example 8.

Explanation of symbols

  1 Primary particles

Claims (6)

A metal can lid coating composition comprising particles of the thermoplastic resin having an average primary particle size of 10 to 1000 nm obtained by cooling a solution of the thermoplastic resin. The metal can lid coating composition according to claim 1, further comprising a thermosetting resin. A method for producing a metal can lid coating,
(A) obtaining a solution obtained by dissolving a thermoplastic resin in an organic solvent;
(B) cooling the solution to obtain a suspension of particles of the thermoplastic resin having an average primary particle size of 10 to 1000 nm;
(C) separating the particles from the suspension; and (d) dispersing the separated particles in a solvent.
A manufacturing method comprising: Furthermore, the manufacturing method of Claim 3 including the process of adding a thermosetting resin to the coating material obtained by (e) process (d). A metal can lid coated with the metal can lid coating composition according to claim 1. A method of manufacturing a metal can lid,
(F) a step of applying the metal can lid covering paint according to claim 1 or 2 to a metal plate, and (g) a step of melting the particles by heating the applied paint.
A manufacturing method comprising:

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