JP2003183481A - Pigment-containing polyester resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment-containing polyester resin composition which is prevented from edge waving and excess neck-in when formed into a film and gives a film having a flat part with an increased width and a thickness varying little and improved in yield and adhesion to a substrate. <P>SOLUTION: This resin composition is prepared by dispersing an inorganic pigment in a thermoplastic polyester resin and comprises 100 pts.wt. thermoplastic polyester resin, 0.5-150 pts.wt. ethylene polymer, and 250 pts.wt. or lower inorganic pigment. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pigment-containing polyester resin composition, and more specifically, it prevents swaying and excessive neck-in during film formation, increases the film width of a flat portion, and The present invention relates to a pigment-containing polyester resin composition having improved yield and improved adhesion to a substrate. The present invention further relates to a pigment-containing film formed from the above resin composition, a laminated plate in which the film is coated on a metal plate, and a can body and a can lid formed from the laminated plate.

[0002]

2. Description of the Related Art Heretofore, as a means for imparting corrosion resistance to a metal material, it has been widely practiced to coat a metal surface with a resin layer, and as a coating method used in such a technique,
Epoxy resin, phenolic resin, acrylic resin, polyester resin, etc. A thermosetting resin dispersed in a solvent is applied to a metal surface, or a preformed film such as polyester, olefin resin, polyamide There is known a method of laminating a film of a type or the like with a metal base material via an adhesive of an isocyanate type, an epoxy type, a phenol type or the like.

It is also widely known to utilize the heat-sealing property of a thermoplastic resin for laminating a metal substrate and a thermoplastic resin. In this method, a preformed film of a thermoplastic polyester resin or the like is used. There is known a method of bonding a metal sheet to a metal plate by thermal bonding, and a method of bonding a molten thin film of extruded thermoplastic polyester resin or the like to the metal plate.

[0004] US Pat. No. 5,407,702 (Japanese Patent Publication No. 11-503378) describes a method of coating resin on both sides of a metal strip by extrusion while forming a film, such as a metal such as an aluminum alloy. Strip the strip into a preconditioner, two extrusion dies,
It is described to be moved through a post-heater and cooling system and coated on both sides of the strip with a thin coating of polyester material.

The resin film used for coating the outer surface of the metal substrate may be preliminarily incorporated with a pigment to color the resin film,
It is already known to provide concealment power. For example, the titanium dioxide-containing polyester film layer present on the outer surface of a seamless can hides the chromium surface treatment layer to make the printing ink layer stand out and to improve the transmission of wrinkle holding force during the drawing and redrawing process. It has been found that although it has desirable effects such as preventing the generation of wrinkles and assisting the rust preventive power, the following problems still exist.

[0006]

That is, when the blending amount of an inorganic pigment such as titanium dioxide in the film is increased in order to improve the hiding property, the melt viscosity of the resin composition decreases,
There is a problem that whirling occurs during film formation, the neck-in amount becomes excessive, the film width of the flat part is reduced, and the product yield is reduced. In particular, when wobbling occurs, not only is the film width of the flat portion reduced, but also film thickness fluctuations occur in the longitudinal direction of the film, making it unsuitable as a product.

When a resin having a low intrinsic viscosity (IV) is used for the purpose of reducing the cost of the resin coating layer, the melt viscosity of the resin composition is further lowered,
The film-forming property becomes extremely poor, which makes industrialization difficult.
Similarly, when a recycled product recovered from a PET bottle is used, the melt viscosity of the molten resin composition also decreases due to the decrease in the molecular weight, which makes film formation difficult.

Therefore, the object of the present invention is to prevent swaying and excessive neck-in at the time of film formation, increase the film width of the flat part, reduce the film thickness variation, improve the product yield, and Another object of the present invention is to provide a pigment-containing polyester resin composition having improved adhesion to a material. Another object of the present invention is to form a pigment-containing film formed from the above resin composition and having a uniform thickness and physical properties, a laminated plate obtained by coating the film on a metal plate, and a can body and a can formed from the laminated plate. To provide a lid.

[0009]

According to the present invention, a resin composition prepared by dispersing an inorganic pigment in a thermoplastic polyester resin is used in an amount of 0.5 to 150 parts by weight per 100 parts by weight of the thermoplastic polyester resin. Provided is a pigment-containing polyester resin composition comprising an ethylene polymer and 250 parts by weight or less of an inorganic pigment. In the pigment-containing polyester resin composition of the present invention, 1. 1. The ethylene polymer contains an ionomer, 2. The inorganic pigment is titanium dioxide, Ethylene polymer is thermoplastic polyester resin 10
It is preferably present in an amount of 0.5 to 10 parts by weight per 0 parts by weight. According to the present invention, there is also provided a pigment-blended film comprising the above-mentioned inorganic pigment-blended polyester resin composition. The pigment-containing film is preferably formed by forming a resin composition through a slit die. According to the present invention, there is further provided a laminate plate characterized in that at least one surface of a metal plate is coated with the pigment-containing film. This laminated plate is useful for manufacturing can bodies and can lids.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION [Function] According to the present invention, by blending an ethylene-based polymer with an inorganic pigment-blended polyester, the melting characteristics of the resin composition are improved, and whirling during film formation is suppressed. Further, it is possible to suppress the neck-in amount, improve the productivity of the pigment-containing polyester film, and further improve the uniformity of the film thickness.

In FIG. 1 for explaining the occurrence of neck-in during the film formation of the polyester resin composition, the molten film 2 of the polyester resin composition is extruded from the T die 1, and at this time, the edge of the molten resin film 2 is extruded. (Ear) 3 is T
It is formed in a state of being recessed inward from the edge of the slit of the die 1 or its extension line 4. The occurrence of neck-in is due to the shape memory property of the molten resin, and the degree of neck-in becomes large in the case of low melt viscosity, low melt tension, and low extensional viscosity. Further, as the film forming speed increases, the degree of neck-in tends to increase. Degree of neck-in during film formation, that is, neck-in amount (A
n) is defined as the distance from the edge extension line 4 of the T-die slit to the edge 3 of the molten resin film. The neck-in amount (An) increases as the distance from the T die in the extrusion direction increases, but tends to saturate at a certain value.

In FIG. 2 for explaining the occurrence of wobbling at the time of film formation of the polyester resin composition, T-die 1
The molten resin film 2 extruded from the not only causes the neck-in described with reference to FIG. 1, but may also cause whirling that the edges (ears) of the molten resin film 2 meander inward and outward. The degree of wobbling tends to increase with a low melt viscosity, a low melt tension, and a low elongation viscosity, and tends to increase with an increase in the film forming speed. Regarding the degree of swaying noise, by comparing the same molten resin film with the largest neck-in amount (Anma) and the smallest neck-in amount (Anmi),
Can be evaluated.

See the example below. The neck-in amount (Anmi-Anma) when a resin composition obtained by mixing 30% by weight of TiO2 with modified polyethylene terephthalate (PET / IA5) containing 5% by weight of isophthalic acid unit was extruded from a 400 mm wide T-die was as shown in the table. 1, the film-forming speed was 20 m / min, 60-65 mm, and the film-forming speed was 50 m / min, 45-105 mm. In the case of blending 5% by weight of ionomer, the neck-in amount is 40 mm at a film forming speed of 20 m / min,
Further, the film-forming speed is 50 mm at 50 m / min, and thus the neck-in amount is suppressed to be small and the occurrence of whistling is suppressed.

Further, in FIG. 3 showing the relationship between the film forming rate and the film thickness in this example, the plot (●) in the figure shows the resin composition containing the ionomer, and the plot (■) shows the resin containing no ionomer. The composition, the bars above and below show the fluctuation range, in the resin composition of the ionomer blend, as compared with the resin composition of the ionomer unblended, as a result of suppressing the neck-in amount small, the film It becomes clear that the thickness is small and the fluctuation of the film thickness is also suppressed as a result of suppressing the occurrence of whirling.

As already pointed out, when the amount of the inorganic pigment such as titanium dioxide added to the polyester resin is increased,
The neck-in amount of this resin composition increases, and the tendency of tinnitus to occur also increases. In FIG. 4 of the accompanying drawings, the amount of titanium dioxide mixed with the polyester resin is plotted on the horizontal axis, and the weight average molecular weight (Mw) of the polyester resin blended with titanium dioxide is plotted on the vertical axis. In this figure, the right side of the horizontal axis shows the direction in which the hiding property of the resin film increases due to the increase in the pigment concentration, and the lower direction of the vertical axis shows the direction in which the molecular weight decreases and the film-forming property decreases. From the results of FIG. 4, in the titanium dioxide-containing polyester resin composition, the improvement of the hiding property and the improvement of the film forming property are opposite to each other,
It is clear that an attempt to improve the hiding property results in a decrease in film forming property.

Generally, thermoplastic resins are classified into radical decomposition type and radical crosslinking type, but it is known that the thermoplastic polyester resin is a typical radical decomposition type resin. The results in FIG. 4 show that increasing the amount of titanium dioxide compounded promotes thermal degradation of the polyester resin during melt-kneading.

In the present invention, a polyester resin composition containing an inorganic pigment is blended with an ethylene polymer such as an ionomer to prepare a resin composition even when the amount of a pigment such as titanium dioxide is large. The film property can be maintained at an excellent level. Thus, according to the invention,
By adding an ethylene polymer to the pigment-blended resin composition, the hiding power of the film is improved by increasing the pigment concentration in the film covering the substrate such as metal without lowering the film-forming property of the film. Can be made. It is possible to use a low-cost polyester resin having a low intrinsic viscosity (IV) in the production of a pigment-containing film without lowering the film-forming property of the film, thereby reducing the production cost of the laminate. It will be possible. Further, similarly, it is possible to use the recycled polyester resin having a lowered degree of polymerization without deteriorating the film forming property of the film, which can be useful for environmental protection.

In the present invention, the effect of improving the film-forming property of the polyester resin composition containing an inorganic pigment by adding an ethylene polymer such as an ionomer has been found as a phenomenon as a result of many experiments. Yes,
The reason for this is not completely clear, but the sea-island structure is formed by blending the polyester resin with the ethylene polymer, and this structure makes the stress of the film uniform during the extensional flow of the resin film exiting the T-die. It is considered that the film-forming property is improved due to the effect that the film is made uniform and the film is uniformly stretched.

[Polyester Resin] In the present invention, as the base polyester resin, all the polyester resins used in the production of this type of pigment-containing polyester film can be used. Among these, a polyester mainly composed of ethylene terephthalate, that is, a polyester in which 50 mol% or more of the dicarboxylic acid component is composed of a terephthalic acid component and 50% or more of an alcohol component mainly composed of an aliphatic diol is composed of an ethylene glycol component, preferable. As long as the above conditions are satisfied, the polyester resin may be a homopolyester, a copolyester, or a blend of two or more of these.

As the carboxylic acid component other than the terephthalic acid component, isophthalic acid, naphthalenedicarboxylic acid, p-
β-oxyethoxybenzoic acid, biphenyl-4,4′-
Examples thereof include dicarboxylic acid, diphenoxyethane-4,4′-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, trimellitic acid and pyromellitic acid.

On the other hand, alcohol components other than ethylene glycol include propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, and bisphenol A ethylene oxide. Examples thereof include adducts, alcohol components such as glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitan.

A preferred polyester resin is mainly composed of ethylene terephthalate units and 0.1 to 50% by weight, particularly 0.5 to 30% by weight of ethylene isophthalate units.
It is an isophthalate-modified polyethylene terephthalate contained in an amount of 10%, which gives excellent film-forming properties in combination with an inorganic pigment and an ethylene-based polymer.

The polyester resin used should have a molecular weight sufficient to form a film, for which the intrinsic viscosity (IV) is 0.55 to 1.9 dl / g, especially 0.65 to 1.4 d.
Those in the l / g range are desirable. That is, the intrinsic viscosity (I
V) within this range is preferable in terms of film forming properties, film physical properties such as barrier properties against corrosive components and mechanical properties.

[Inorganic Pigment] The above polyester resin includes
An inorganic pigment is contained for the purpose of hiding a substrate such as a metal plate. This inorganic pigment is 100 when measured by a laser scattering method.
From the viewpoint of dispersibility in the resin, it is desirable to have an average particle diameter (volume-based median diameter, D50) of not more than μm. In particular, in the case of titanium dioxide, it is desirable that it has an average particle size of 1.0 μm or less from the viewpoint of dispersibility in the resin.

Examples of the inorganic pigments or fillers include inorganic white pigments such as rutile or anatase type titanium dioxide, zinc white, and gloss white; barite, precipitated barium sulfate, calcium carbonate, gypsum, precipitated silica, aerosil, talc. , Calcined or uncalcined clay, barium carbonate,
Alumina white, white pigments such as synthetic or natural mica, synthetic calcium silicate, magnesium carbonate; black pigments such as carbon black and magnetite; red pigments such as red iron oxide; yellow pigments such as Siena; blue pigments such as ultramarine blue and cobalt blue. Mention may be made of pigments. Among these pigments, titanium dioxide is particularly preferable in terms of hiding the surface of the metal plate and obtaining a white color that makes the printing ink layer stand out,
In terms of dispersibility in polyester resin and suppression of molecular weight reduction,
It is more preferable that it is a rutile type and has been subjected to a surface treatment such as a polyol type, amine type, siloxane type or silane type.

[Ethylene-based Polymer] In the present invention, the ethylene-based polymer which is a modifier component of the polyester resin is a polymer whose main constituent monomer is ethylene, for example, low-, medium-, or High-density polyethylene, linear low-density polyethylene, linear ultra-low density polyethylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer,
Examples thereof include ethylene-vinyl acetate copolymers, acid-modified ethylene-based polymers, ion-crosslinked ethylene copolymers (ionomers), and ethylene-acrylic acid ester copolymers.

It is preferable that at least 10% by weight, preferably 50% by weight or more of the constituent monomers of these ethylene polymers are composed of ethylene.
Melt flow rate (MF at 2160g load)
R) is 0.05 to 20 g / 10 minutes, especially 0.1 to 10 g
It is preferable to use / 10 minutes.

Suitable ethylene-based polymers are those containing an unsaturated carboxylic acid unit which may be neutralized, and as the unsaturated carboxylic acid, acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, Examples thereof include fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, monomethyl maleate, monoethyl maleate and the like. Especially preferred is acrylic acid or methacrylic acid.

Other preferred ethylene-based polymers are those containing units of polar group-containing monomers other than unsaturated carboxylic acids, and such other monomers include vinyl acetate,
Vinyl esters such as vinyl propionate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, methacryl Unsaturated carboxylic acid esters such as isobutyl acid, dimethyl maleate, diethyl maleate, carbon monoxide,
Sulfur dioxide etc. can be illustrated.

Among these, an ion in which a part or all of the carboxyl groups in the copolymer of ethylene and unsaturated carboxylic acid or further unsaturated carboxylic acid ester is neutralized with a metal and / or organic cation. Ionomer, which is a natural salt, can be preferably used. The metal ion for neutralizing the carboxyl group in the copolymer is Na
+, K +, Li +, Zn +, Z2 +, Mg2 +, Ca2
+, Co2 +, Ni2 +, Mn2 +, Pb2 +, Cu2
+ Etc. can be mentioned. As an organic cation,
Examples include primary, secondary or tertiary amines.

[Resin Composition] In the resin composition of the present invention, 0.5 to 150 parts by weight, and particularly preferably 0.5 to 10 parts by weight of the ethylene polymer is used per 100 parts by weight of the thermoplastic polyester resin. It is recommended to be present in an amount. When the blending amount of the ethylene-based polymer is less than the above range, the effect of improving the film-forming property becomes insufficient, while when the blending amount of the ethylene-based polymer exceeds the above-described range, spots derived from the ethylene-based polymer are generated. Or, the dispersibility with the polyester resin or the inorganic pigment is deteriorated, and the physical properties of the film are impaired.

The inorganic pigment is preferably contained in an amount of 250 parts by weight or less, particularly 150 parts by weight or less, based on the thermoplastic polyester resin. When the content of the inorganic pigment exceeds the above range, the dispersibility with the polyester resin or the ethylene polymer cannot be formed, and a homogeneous film cannot be formed, or the physical properties of the film after forming become brittle, and a laminate material It is easy to cause problems such as difficult machining.

The pigment-containing polyester composition of the present invention contains a compounding agent known per se, for example, an anti-blocking agent such as amorphous silica, various antistatic agents, lubricants, antioxidants, ultraviolet absorbers, and light-absorbing agents. Stabilizers, heat stabilizers and the like can be blended according to a formulation known per se.

The polyester resin, the ionomer resin, and the inorganic pigment can be blended by dry blending or melt blending depending on the amount of the components to be blended. In the former case, the resin is blender, Henschel mixer, super mixer, etc. And the mixture may be directly fed to the hopper of the extruder, and in the latter case, it may be kneaded with a single-screw or twin-screw extruder, a kneader, a Banbury mixer, or the like. In any of these cases, the polyester resin, the ionomer resin, and the inorganic pigment are finally blended at a temperature equal to or higher than the melting temperature of the polyester resin. It is also possible to produce a masterbatch containing an inorganic pigment or the like in a relatively high concentration and blend the masterbatch with a polyester resin.

[Film Forming] According to the present invention, the above polyester resin composition containing an inorganic pigment is treated with a T-die (slit die).
And melt-extruded to form a film. The film formation can be performed by any means known per se, and for example, an unstretched film can be formed by a so-called T-die method in which an extruded molten resin film is rapidly cooled. Further, this unstretched film can be biaxially stretched simultaneously or successively to obtain a biaxially stretched film. Alternatively, the laminate plate can be manufactured by an extrusion coating method in which the extruded molten resin film is directly coated on a substrate such as a metal plate.

The pigment-containing polyester film used in the present invention has a total thickness of 2 to 50 μm, particularly 5 to 50 μm.
It is preferably in the range of μm. When the thickness of the film is smaller than the above range, the hiding property and corrosion resistance to the substrate are not sufficient, while when it is larger than the above range, the workability of the laminate material, for example, drawing and ironing property, tends to decrease.

[Laminated Plate] The laminated plate of the present invention can be produced by thermally adhering a molten resin film or film of the pigment-containing polyester resin composition to a metal substrate. In FIG. 5, the concealing layer 1 was formed by forming the inorganic pigment-containing polyester resin composition of the present invention as a single layer film.
1 is an example in which it is laminated on the substrate 10. When problems such as the inorganic pigment obstructing the adhesion with the substrate 10 and the abrasion of the molding tool when the laminated plate is processed into a can body or the like occur, the inorganic pigment-containing polyester resin of the present invention is used as a multilayer film. Compositions can also be used. For example, FIG. 6 shows an example in which a concealing layer 11 composed of the polyester resin composition containing an inorganic pigment of the present invention, a concealing layer 12, and a three-layer film having a polyester resin containing no inorganic pigment as a protective layer 13 are laminated on a substrate 10. is there. Concealing layer 11
Is a polyester resin composition containing an inorganic pigment containing sufficient inorganic pigment to conceal the substrate 10.
2 is made of an inorganic pigment-containing polyester resin composition in which only a small amount of an inorganic pigment is added to attach importance to the adhesiveness to the substrate 10, and the protective layer 13 is a polyester containing no inorganic pigment in order to suppress abrasion of the molding tool. It consists of a single resin. By forming multiple layers in this way, adhesion with the substrate,
It is possible to obtain a film which has no problem in terms of wear of the molding tool and has excellent concealing properties and film forming properties. The layer structure of the multilayer film is not limited to the examples described above.

As the metal plate used in the present invention, various surface-treated steel plates and light metal plates such as aluminum are used. As the surface-treated steel sheet, a cold-rolled steel sheet is annealed and then secondary cold-rolled, and one or more surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment are performed. Can be used. Further, an aluminum-coated steel plate that has been subjected to aluminum plating, aluminum rolling, etc. is used. Further, as the light metal plate, an aluminum alloy plate is used in addition to the so-called pure aluminum plate. The original plate thickness of the metal plate varies depending on the type of metal, the use or size of the container, but it is generally preferable to have a thickness of 0.10 to 0.50 mm. Thickness of 10 to 0.30 mm,
In the case of a light metal plate, it should have a thickness of 0.15 to 0.40 mm.

In the present invention, the pigmented polyester coating layer can be formed on the metal substrate by any means, for example, extrusion coating method, cast film heat bonding method, biaxially stretched film heat bonding method and the like. be able to. In the case of the extrusion coating method, the number of extruders corresponding to the type of resin is used to extrude the pigment-containing polyester resin composition through a die, and this is extruded on a metal substrate in a molten state and heat-bonded. .

In FIG. 57 for explaining the production of a laminated plate by the extrusion coating method, this device is a T-die 120 for extruding the pigment-containing resin composition 221 into a film and a heating device 623 for heating the metal base material 522. And warm laminating rolls 6a, 6b 24a, 24 for heat-sealing the extruded film 221 and the metal base material 522 at the nip position.
b and cooling devices 8, 926 and 27 for quenching the formed laminate material 725.

On the other hand, when a preformed pigment-containing polyester film is used, a film formed by the T-die method or the inflation film forming method is used. As the film, an extruded film may be rapidly cooled, and an unstretched film by a cast molding method may be used.Also, the film may be biaxially stretched sequentially or simultaneously at a stretching temperature, and the film after stretching may be heat-fixed. The biaxially stretched film produced by can also be used.

In the present invention, various constitutions other than those described above can be adopted, and a conventionally known adhesive primer can be provided between the metal substrate and the pigment-containing polyester layer. This adhesive primer exhibits excellent adhesiveness to both a metal material and a film. As a primer coating having excellent adhesion and corrosion resistance, there is a phenol-epoxy type coating composed of a resol-type phenol aldehyde resin derived from various phenols and formaldehyde and a bisphenol-type epoxy resin. It is a coating material containing a resin in a weight ratio of 50:50 to 1:99, particularly 40:60 to 5:95. Generally, the adhesive primer layer should be provided in a thickness of 0.01 to 10 μm. The adhesive primer layer may be provided on the metal material in advance, or may be provided on the polyester film.

[Metal Can and Manufacturing Method Thereof] The metal can made of the pigment-containing resin-coated metal plate of the present invention may be produced by any can manufacturing method as long as it is formed from the resin-coated metal plate described above. The metal can can be a three-piece can having a side seam, but is generally preferably a seamless can (two-piece can). This seamless can
Squeezing, re-squeezing, drawing, so that the coated surface of the polyester composition of the resin-coated metal plate described above is the inner surface of the can.
It is manufactured by subjecting it to a conventionally known means such as bending and stretching (stretching) by redrawing, bending and stretching / ironing by drawing / redrawing, or drawing / ironing. The metal can of the present invention is manufactured by the above means, but it is preferable to perform bending and stretching by redrawing and / or ironing to reduce the thickness of the side wall portion. The thinning is performed by bending and stretching the side wall portion and / or ironing the bottom wall portion so that the side wall portion has a thickness of 20 to 95%, particularly 30 to 85% of the thickness of the base metal sheet of the resin-coated metal plate. It is preferable that they are

For example, according to bending and stretching by drawing and redrawing, a drawing ratio of 1.1 to 3.
A pre-drawing cup is formed by drawing in the range of 0, and this cup is re-drawn by a re-drawing punch and a re-drawing die in a drawing ratio range of 1.5 to 5.0, and the action of the re-drawing die is performed. Corner radius of curvature (Rd)
Is 1 to 2.9 times the metal base plate thickness (tB), especially 1.5
The thickness can be effectively reduced by bending and stretching with a dimension of 2.9 to 2.9 times, the variation in thickness between the lower portion and the upper portion of the side wall portion is eliminated, and uniform thinning is achieved over the entire side wall portion. It will be possible. In general, the side wall portion of the can body can be thinned to a thickness of 80% or less, and up to 45%, particularly up to 40%, based on the base plate thickness (tB).
In the redrawing process, the ironing process can be performed on the side wall by disposing the ironing process behind the bending and stretching process part of the redrawing die.

By bending and stretching and ironing, the following equation (2) RI = {(tB-tW) / tB} × 100 (2) In the equation, tB is the thickness of the blank and tW is the thickness of the side wall. Is. It is preferable to reduce the thickness so that the thickness reduction ratio RI defined by is 20 to 95%, particularly 30 to 85%.

The obtained can is subjected to at least one heat treatment to remove residual strain of the film caused by processing,
The lubricant used during processing is volatilized from the surface, and the printing ink printed on the surface is dried and cured. After the heat treatment, the container is rapidly cooled or left to cool, and if desired, subjected to one-step or multi-step neck-in processing and flange processing to obtain a can for tightening.

[Can Lid and Manufacturing Method Thereof] As long as the can lid made of the pigment-containing resin-coated metal plate of the present invention is formed from the above-mentioned resin-coated metal plate, any conventionally known lid manufacturing method such as press molding can be used. It may be by law. Generally, it is applied to stay-on-tab type easy-open lids and full-open type easy-open lids.

[0048]

The present invention will be further described in the following examples. [Production of Film] In Examples and Comparative Examples, the raw materials were premixed so as to have the compositions shown in Table 2, and the extrusion amount was 10
It is charged into a twin-screw extruder at kg / h, melt-kneaded, and the die width is 4
The web extruded through a 00 mm T-die was cooled by a cooling roll, and the obtained film was wound to obtain a cast film. At this time, the film was formed by setting the distance air gap between the lip of the T-die and the cooling roll to 40 mm. A film was formed without using auxiliary devices (pinning device, air clip, etc.) for suppressing neck-in.

The evaluation method is as follows: [IV (intrinsic viscosity)] After measuring 200 ± 0.2 mg of PET raw material chips vacuum dried for at least 24 hours, phenol: 1,1,2,2- Tetrachloroethane = 1:
The mixture is added to 20 ml of a mixed solvent of 1 (weight ratio), dissolved in an oil bath at 130 ° C. with stirring for about 30 minutes, and allowed to cool to room temperature. Then, the solution at room temperature is filled with a Ubbelohde viscometer fixed in a constant temperature water bath of 30 ± 0.1 ° C. through a glass filter, and when the temperature is stable, the dropping time is measured 3 times. The result measured by the above method was substituted into the following formula, and the calculated result was defined as IV (intrinsic viscosity).

[Formula 1]

[Neck-in Amount] The neck-in amount An was calculated by substituting _T -die width W _T and the width of the formed film W _{f into} the following formula.

[Formula 2] An = (W _T −W _f ) / 2 where W _T = 400 mm

[Average Film Thickness] The film thickness at several flat portions excluding the film edge was measured with a film pressure gauge to obtain the average film thickness. Depending on the material composition and the film forming speed, the neck-in amount may fluctuate during the film formation (waviness), and the film thickness may fluctuate in the longitudinal direction of the film. When the neck-in amount fluctuates in this way, the film thickness of the portion excluding the edge portion of the portion where the neck-in amount is the center value of the fluctuation is measured,
An average value was calculated and evaluated as a film thickness average value.

[Film Thickness Variation Value] The film thickness of the film portion where the variation in the neck-in amount is maximum and minimum is measured excluding the edge portion, and the average value of each is measured to obtain the maximum film thickness value (maximum neck-in amount). Time) and the minimum value of the film thickness (when the neck-in amount is minimum), and the difference between them is evaluated as the film thickness variation value.

[Film Thickness Accuracy] The ratio of the film thickness variation value to the film thickness average value was calculated and evaluated.

[Determination] The film-forming property was evaluated according to the following criteria and summarized in Table 2. Judgment criteria of film formability evaluation ○ (good): Film thickness accuracy of less than 5% × (poor): Film thickness accuracy of 5% or more If film thickness accuracy of 5% or more, can processability after lamination to a metal plate Further, there are problems that the lid-making processability is inferior and that the color tone of the product varies.

[Examples 1 to 3] When a film was formed using the composition A of Table 2 at the film forming rate shown in Table 3, the neck-in amount was stable as shown in Table 3, and the film thickness accuracy was shown. Was good and the film forming property was good.

Example 4 As in Table 1, as shown in Table 2, except that a mixture of an ionomer and an ethylene / butene copolymer as an ethylene-based polymer was added at a mixing ratio of 1: 1 in a total amount of 7.7 parts by weight. When film molding was performed in the same manner, the neck-in amount was stable as shown in Table 3, the film thickness accuracy was good, and the film forming property was good.

[Examples 5 to 13] Film formation was carried out using the composition A of Table 2 at the film forming speed shown in Table 3, and the neck-in amount was stable or varied slightly as shown in Table 3. The film thickness accuracy was good, and the film forming property was good.

[Comparative Examples 1 to 9] Using the compositions shown in Table 2 and performing film forming at the film forming rates shown in Table 3, the neck-in amount fluctuates as shown in Table 3 and the film thickness accuracy is shown. Is 5.
It was 0% or more, and the film forming property was poor.

[Comparative Example 10] [Table 3]
When the film was formed at the film-forming speed shown in (1), the dispersion was likely to be caused by the excess of the ethylene polymer, and the film could not be formed.

Comparative Example 11 The composition of Table 2 was used, and Table 3 was used.
When the film was formed at the film-forming speed shown in (1), it was impossible to form a film due to defective dispersion probably caused by excess inorganic pigment.

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

According to the present invention, in a resin composition prepared by dispersing an inorganic pigment in a thermoplastic polyester, 0.5 to 150 parts by weight of an ethylene polymer is added per 100 parts by weight of the thermoplastic polyester resin. By containing 250 parts by weight or less of an inorganic pigment, whilst imparting sufficient concealing property to the formed film, whirling and excessive neck-in are prevented during film formation, and the film width of the flat part is increased. In addition, the film thickness variation is small, and the product yield can be improved. According to the present invention, there is provided a pigment-containing film formed from the above resin composition and having a uniform thickness and physical properties, and a laminated plate obtained by coating the film on a metal plate can be used for manufacturing a can body and a can lid. it can.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining the occurrence of neck-in during film formation of a polyester resin composition.

FIG. 2 is an explanatory diagram for explaining the occurrence of tinnitus during film formation of a polyester resin composition.

FIG. 3 is a graph showing the relationship between the film formation speed and the film thickness of a pigment-containing polyester resin composition.

FIG. 4 is a graph in which the abscissa represents the blending amount of titanium dioxide with respect to the polyester resin and the ordinate plots the weight average molecular weight (Mw) of the polyester resin blended with titanium dioxide.

FIG. 5 is a reference diagram in which a pigment-containing polyester resin composition is formed as a single-layer film and laminated on a substrate as a concealing layer.

FIG. 6 is a reference diagram in which a pigment-containing polyester resin composition is formed into a multilayer film and laminated as a hiding layer on a substrate.

FIG. 7 is an explanatory diagram for explaining the production of a laminated plate by an extrusion coating method.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C23C 26/00 C23C 26/00 ZF term (reference) 3E061 AA16 AB13 BA01 BA02 BB01 DA02 4F071 AA46 AA78 AB18 AE09 AH05 BB06 BC01 BC12 BC17 4J002 BB232 CF001 DE136 FD096 GF00 GG02 GH00 4K044 AA02 AA06 AB02 AB03 BA02 BA06 BA10 BA21 BB01 BB03 BB04 BC05 CA11 CA16 CA53

Claims (9)

[Claims] 1. A resin composition in which an inorganic pigment is dispersed in a thermoplastic polyester resin, wherein 0.5 to 150 parts by weight of an ethylene polymer and 250 parts by weight or less per 100 parts by weight of the thermoplastic polyester resin. 2. A pigment-blended polyester resin composition comprising the above-mentioned inorganic pigment. 2. The polyester resin composition according to claim 1, wherein the ethylene polymer contains an ionomer. 3. The resin composition according to claim 1 or 2, wherein the inorganic pigment is titanium dioxide. 4. The resin composition according to claim 1, wherein the ethylene polymer is present in an amount of 0.5 to 10 parts by weight per 100 parts by weight of the thermoplastic polyester resin. 5. A pigment-containing film comprising the resin composition according to any one of claims 1 to 4. 6. The pigment-containing film according to claim 5, wherein the resin composition is formed into a film through a slit die. 7. The method according to claim 5, wherein the metal plate is provided on at least one surface thereof.
Alternatively, a laminated plate coated with the pigment-containing film according to item 6. 8. A can body formed from the laminate plate according to claim 7. 9. A can lid, which is formed from the laminate plate according to claim 7.