JP2001353814A - Resin-coated metal plate, can and can lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-coated metal plate which satisfies can performance and quality such as an improvement of coating film forming properties, superb working properties and high impact resistance (dent resistance), adhesion and flavor upkeep with such other advantages that a general-purpose polyester resin can be used and adhesive properties can be retained without the use of a primer and cost can be cut as well as a resin-coated metal can and a metal lid. SOLUTION: In the resin-coated metal plate consisting of a metal plate and a coating layer of an ionomer-blended thermoplastic polyester formed on the surface of the metal plate, the molten viscosity at a temperature of 260 deg.C and a shear rate of 122 sec-1 is 200-10,000 cP. and the intrinsic viscosity(IV) of the thermoplastic polyester of the coating layer is within the range of 0.6-1.5 and further, the average particle diameter of the ionomer resin of the coating layer is 5 μm or less in the form of a disperse phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin-coated metal plate,
For cans and lids, more specifically, a resin-coated metal plate having excellent impact resistance (particularly dent resistance) and film forming property, and excellent in workability and impact resistance and corrosion resistance after retort treatment,
And a can and a can lid formed from the resin-coated metal plate.

[0002]

2. Description of the Related Art Side seamless cans (seamless cans) are drawn from a resin-coated metal plate that has been previously coated with an organic coating on a metal material.
It is formed by bending and stretching (stretching) or ironing. However, the inner organic coating is susceptible to damage by the tool in the above-mentioned processing step. Metal exposure and metal elution and corrosion from this part. In the production of seamless cans, plastic flow occurs in which dimensions increase in the height direction of the can and decreases in the circumferential direction of the can. As the force decreases, the adhesion between the two also tends to decrease over time due to residual strain in the organic coating, etc., and this tendency is caused by hot-filling the contents for canning or changing the canning temperature from low to high. This is particularly noticeable when sterilizing by heating.

[0003] As practical impact resistance required for actual canned products, there is what is called dent resistance. This means that even if the canned product falls or collides with each other and a dent called a dent occurs on the canned product, the adhesion and coverage of the coating can be completely maintained. Is required. That is, if the coating peels off or pinholes or cracks enter the coating in the dent test, metal elution or leakage due to pitting corrosion occurs from this portion, causing a problem of losing the preservability of the contents. . In general, polyesters having excellent content resistance are generally lacking in the property of absorbing or mitigating impact during a dent test, and the provision of these properties is an important issue.

A seamless can using a laminated material in which a polyethylene terephthalate or polyethylene terephthalate / isophthalate film is laminated as an organic coating has excellent barrier properties against corrosive components and excellent workability. When the contents are filled in a container and aged, there is a problem that the impact resistance of the can-coated film is significantly reduced.

[0005] To solve such a problem, Japanese Patent Application Laid-Open No. 7-195617 discloses a method in which a dicarboxylic acid and a dihydroxy compound are used on both sides or one side of a metal plate and a dicarboxylic acid component is 100 mol%. A saturated polyester resin 75 to 9 in which the dicarboxylic acid component is composed of 50 to 95 mol% of terephthalic acid and 50 to 5 mol% of isophthalic acid and / or orthophthalic acid, and the dihydroxy component is a compound containing ethylene glycol as a main component.
A resin-coated metal plate provided with a coating of a resin composition comprising 5 parts by weight and 1 to 25 parts by weight of an ionomer resin is described.

[0006]

The above-mentioned resin-coated metal plate has a good flavor while maintaining a certain degree of impact resistance and adhesion. However, in the above-mentioned prior art, a specific polyester resin must be prepared, and in particular, since isophthalic acid is relatively expensive, even when a low-cost general-purpose polyester resin is used, high impact resistance and adhesion, and It is desired to have flavor properties. In addition, when an ionomer resin is blended with a general-purpose polyester resin, there is a new technical problem that bumps occur due to aggregation of the ionomer resin.

[0007] Further, there is a demand for further improvement of the adhesion of the resin coating layer to the metal substrate and further improvement of the workability for high-speed can making. Furthermore, even if the contents are strongly acidic and corrosive, the retort sterilization and the improvement of the high humidity and heat resistance to withstand the aging over time, the improvement of the impact resistance after the retort sterilization, the retort sterilization and after impact Improvement of corrosion resistance is also an important technical issue.

Accordingly, an object of the present invention is to improve the film forming property of a resin-coated metal sheet, to be excellent in workability, and to satisfy the can performance such as impact resistance (dent resistance), adhesion and flavor. By providing a resin-coated metal plate, a resin-coated metal can, and a metal lid, which can use a general-purpose polyester resin and have an adhesive property without using a primer, thereby enabling cost reduction. is there.
Another object of the present invention is to provide a resin-coated metal sheet having excellent workability for high-speed production, and excellent impact resistance and corrosion resistance after retort sterilization. Still another object of the present invention is to provide a metal can and a can lid having these characteristics.

[0009]

According to the present invention, there is provided a resin-coated metal plate comprising a metal plate and a coating layer of an ionomer-blended thermoplastic polyester applied to the surface of the metal plate. Shear rate 122se
The melt viscosity at c- ¹ is 2,000 to 10,000 centipoise, the intrinsic viscosity (IV) of the thermoplastic polyester in the coating layer is in the range of 0.6 to 1.5, and the average of the ionomer resin in the coating layer is A resin-coated metal sheet is provided, which is present as a dispersed phase having a particle size of 5 μm or less. According to the present invention, there is also provided a resin-coated metal can formed by drawing or drawing, bending and stretching or ironing the resin-coated metal plate such that the coating layer is on the inner side of the can. According to the present invention, there is further provided a resin-coated metal can lid formed by molding the resin-coated metal plate such that the coating layer faces the inner surface of the can.

In the resin-coated plate of the present invention, (1) the ionomer resin in the coating layer is an ionomer resin containing zinc as a metal species; and (2) the thermoplastic polyester (A) and the ionomer in the coating layer. The resin (B) is contained in a weight ratio of A: B = 99: 1 to 75:25. (3) A novolak resin of bifunctional phenol, or tocopherol and a derivative thereof are blended in the coating layer. Is preferred.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a resin coating layer is formed at a temperature of 2 ° C.
The melt viscosity at 60 ° C. and a shear rate of 122 sec ⁻¹ is 2,000 to 10,000 centipoise, and the intrinsic viscosity (IV) of the thermoplastic polyester in the coating layer is 0.6 to 10,000.
It is an important feature that the ratio is 1.5 and the ionomer resin is present as a dispersed phase having an average particle size of 5 μm or less in the coating layer.

The ionomer resin is not compatible with the thermoplastic polyester resin and agglomerates in the polyester resin, and exists as a dispersed phase having an average particle size of 5 μm or less.
The excellent characteristics of the ionomer resin such as toughness and abrasion resistance are exhibited in the coating resin without being impaired. Therefore, even when a general-purpose polyester resin is combined as a matrix, impact resistance (particularly, dent resistance), adhesion, and corrosion resistance can be imparted to the general-purpose polyester resin as a matrix. In the present invention, the particle diameter of the dispersed phase of the ionomer resin is involved in the dent resistance, the present inventors have found through experiments and the like, the reason is not clear, but from the results of the examples described below. it is obvious. That is, when the average particle size of the dispersed phase is smaller than 5 μm (Examples 1 to 14), the average current value of a flat dent exhibiting dent resistance is about 0.3 mA, whereas the average particle size is 5 μm. In the case of larger values (Comparative Examples 1 and 2), it is clear that the dent resistance is remarkably inferior when the average current value is about 3.0 mA.

In order to reduce the average particle size of the dispersed phase of the ionomer resin to 5 μm or less, the intrinsic viscosity (IV) of the thermoplastic polyester in the coating layer is in the range of 0.6 to 1.5, especially 0.1 to 0.1. It is important to be in the range of 65-1.2. That is, when the intrinsic viscosity is smaller than the above range, the ionomer resin is not uniformly dispersed in the polyester, and the dispersed particle size is larger than the above range. When the intrinsic viscosity is larger than the above range, the ionomer resin is contained in the coating layer. The effects and dent resistance obtained by dispersing the resin are not sufficiently obtained. In addition, it is important that the intrinsic viscosity is in the above range, particularly for improving the corrosion resistance after retort sterilization. That is, the cause of degradation of polyesters such as polyethylene terephthalate by high-temperature and high-temperature heat treatment after retorting is that a degradation reaction occurs by hydrolysis of the polyester under these conditions, and that thermal crystallization is promoted by a decrease in molecular weight. However, by setting the intrinsic viscosity of the thermoplastic polyester resin in the coating layer to the above range, the barrier property against corrosive components after retort and the mechanical properties are improved, and the corrosion resistance (retort resistance) after retort is improved. It becomes possible.

Further, in order to reduce the average particle size of the dispersed phase of the ionomer resin to 5 μm or less, the temperature of the coating layer must be 260 ° C.
And the melt viscosity at a shear rate of 122 sec ^-1 is 20.
00 to 10000 centipoise, especially 3000 to 800
It is also important to be in the 0 centipoise range. That is, when the melt viscosity is smaller than the above range, the kneading of the resin is insufficient, the ionomer resin is not uniformly dispersed, the dispersion particle size is too large, and the melt viscosity is larger than the above range. In some cases, the extrusion characteristics are inferior. The fact that the melt viscosity is in the above range is also important in terms of processability and dent resistance, and film formability, particularly in preventing occurrence of bumps. That is, when the melt viscosity is smaller than the above range, the film forming property becomes inferior due to the occurrence of bumps, furthermore, it is not possible to obtain sufficient dent resistance, and when the melt viscosity is larger than the above range, Becomes inferior in workability.

(Ionomer resin) An ionomer resin is an ionic salt in which a part or all of the carboxyl groups in a copolymer of ethylene and an α, β-unsaturated carboxylic acid is neutralized with a metal cation. The degree of neutralization, i.e., the ion concentration, affects its physical properties. Generally, the melt flow rate (hereinafter simply referred to as MFR) of an ionomer resin depends on the ion concentration. The higher the ion concentration, the lower the MFR, and the higher the carboxyl group concentration. The higher the carboxyl group concentration, the lower the melting point. Become. Therefore, the ionomer resin used in the present invention is, of course, not limited to this,
FR of 15 g / 10 min or less, especially 5 g / 10 min
0.5 g / 10 min and the melting point is 1
It is desirable that the temperature is not higher than 00 ° C, particularly in the range of 97 ° C to 80 ° C.

Α, β-unsaturated constituents of the ionomer resin
Examples of the carboxylic acid include unsaturated carboxylic acids having 3 to 8 carbon atoms.
Acids, specifically acrylic acid, methacrylic acid, maleic
Acid, itaconic acid, maleic anhydride, maleic acid monomethyi
Esters, monomethyl maleate, etc.
be able to. In particular, suitable base polymers include
Ethylene- (meth) acrylic acid copolymer or ethylene-
(Meth) acrylic acid ester- (meth) acrylic acid copolymer
Coalescence can be mentioned. Also, such ethylene
In copolymers of α and β, β-unsaturated carboxylic acids
Examples of metal ions that neutralize the sil group include Na⁺, K⁺,
Li⁺, Zn⁺, Z ²⁺, Mg²⁺, Ca²⁺, Co
²⁺, Ni²⁺, Mn²⁺, Pb²⁺, Cu^{2 +}Etc.
In the present invention, zinc is particularly preferred.
Is highly neutralized, has a high degree of crosslinking,
Since it has low sensitivity, it can be suitably used. Ma
Residual carboxyls not neutralized by metal ions
Some of the groups may be esterified with lower alcohols
No.

As described above, in the present invention, an ionomer resin is used in a polyester resin as a matrix.
It is an important feature that the ionomer resin is present as a dispersed phase having an average particle size of not more than 0.1 μm, particularly 0.1 to 3.0 μm. When the resin is dissolved in a solvent such as xylene, traces after elution of the ionomer can be observed with a microscope. By measuring the diameter of the trace, the particle size of the dispersed phase of the ionomer resin can be measured.

The ionomer resin (B) is preferably blended with the thermoplastic polyester (A) in a weight ratio of A: B = 99: 1 to 75:25, particularly 90:10 to 80:20. If the amount of the ionomer resin is less than the above range, the impact resistance (dent resistance) and the adhesion cannot be sufficiently improved. Holes may be formed, resulting in poor film forming properties. Also the workability of the polyester resin,
Excellent properties such as corrosion resistance are inferior to those in the above range.

The ionomer resin used in the present invention contains 80 to 99 mol%, preferably 85 to 96 mol%, of a constitutional unit derived from ethylene, 1 to 20 mol% of a constitutional unit derived from an unsaturated carboxylic acid, Preferably, it is contained in an amount of 4 to 15 mol%.

(Polyester Resin) The polyester resin used in the present invention has an intrinsic viscosity in the range of 0.6 to 1.5 in the coating layer, and has a temperature of 260 ° C. in the state of the coating layer blended with the ionomer resin. And a shear rate of 122 sec.
^{As long as} the melt viscosity at ^-1 falls within the range of 2,000 to 10,000 centipoise, a conventionally known general-purpose ethylene-based polyester can be used. Specifically, 50% or more, especially 80% or more of the dicarboxylic acid component is terephthalic acid, and 50% or more, especially 80% of the diol component.
% Is preferably ethylene terephthalate-based polyester having ethylene glycol. The polyester may be a homopolyester, a copolyester, or a blend of two or more thereof.

The carboxylic acid components other than terephthalic acid include isophthalic acid, naphthalenedicarboxylic acid, p-β-
Oxyethoxybenzoic acid, biphenyl-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, trimellitic acid, pyro Merritic acid and the like can be mentioned.

Diol components other than ethylene glycol include 1,4-butanediol, propylene glycol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, and ethylene oxide addition of bisphenol A. Glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitan and the like.

This thermoplastic polyester resin has an intrinsic viscosity of 0.7 to 1.5 in a pellet state measured using a phenol / tetrachloroethane mixed solvent.
, Particularly preferably in the range of 0.8 to 1.2. Furthermore, the glass transition point is 50 ° C. or higher, particularly 60 ° C.
The temperature is preferably in the range of 90 ° C. in order to prevent the elution of the oligomer component into the contents. The intrinsic viscosity of the polyester resin decreases during the process of manufacturing the resin-coated metal sheet. In the present invention, the e-viscosity of the resin coated metal plate is changed from 0.6 to 0.6.
It is necessary to keep in the range of 1.5. After the thermoplastic polyester resin was formed as a coating layer on the metal plate, the intrinsic viscosity of the polyester resin was determined by peeling the coating layer from the resin-coated metal plate, and removing the polyester layer with a solvent such as a phenol / tetrachloroethane mixed solvent. After dissolving the resin component, filtration is performed, and the intrinsic viscosity of the polyester resin in the coating layer can be measured by measuring the intrinsic viscosity of the filtrate.

In the present invention, it is particularly preferable that a novolak resin of a bifunctional phenol, or tocophenol or a derivative thereof is blended in the coating layer.
As described below, the bifunctional phenol novolak resin or tocopherol or a derivative thereof as a polyester resin modifier maintains excellent film adhesion and corrosion resistance even after being subjected to severe mechanical processing and heat treatment. Also, it is excellent in high-temperature, high-humidity and heat resistance, which can withstand aging at high temperature and high humidity after retort sterilization.

(Novolak resin of bifunctional phenol)
In the present invention, a bifunctional phenol novolak resin (novolak phenol resin) is used as a resin modifier.
Is particularly preferred. A polyester film containing a novolak type phenol resin maintains excellent film adhesion and corrosion resistance even after being subjected to severe mechanical processing and heat treatment. In addition, it has excellent resistance to high temperature, humidity and heat, which can withstand aging at high temperature and high humidity after retort sterilization. As described above, polyesters such as polyethylene terephthalate are deteriorated by high-temperature and high-humidity heat treatment after retorting. As described above, degradation reactions due to hydrolysis of polyesters occur under these conditions, and thermal crystallization is promoted by a decrease in molecular weight. However, by blending a small amount of a phenol resin into the polyester, degradation due to hydrolysis of the polyester is suppressed, and the tendency of the resin coating layer to deteriorate is significantly suppressed.

The novolak type phenol resin used in the present invention can be obtained by a method known per se, that is, by reacting a phenol with formaldehyde or a functional derivative thereof in the presence of an acid catalyst and water. The phenol used is not particularly limited, but is preferably a monocyclic monohydric phenol, particularly the following formula (1)

Embedded image In the formula, R1 is a hydrogen atom or an alkyl group or an alkoxy group having 4 or less carbon atoms, two of the three R1s are a hydrogen atom, and one is an alkyl group or an alkoxy group. , R is a hydrogen atom or an alkyl group having 4 or less carbon atoms. A bifunctional phenol such as o
-Mainly one or more of bifunctional phenols such as cresol, p-cresol, p-tertbutylphenol, p-phenylphenol, p-ethylphenol, 2,3-xylenol, 2,5-xylenol, etc. Those are preferred.

On the other hand, the formaldehyde used in the reaction is generally available as a formalin solution.
On the other hand, examples of the functional derivative of formaldehyde include paraformaldehyde and trioxane.

As the acid catalyst, hydrochloric acid, sulfuric acid, phosphoric acid, toluenesulfonic acid, oxalic acid, lactic acid and the like are used.
The amount of formaldehyde to be used relative to the phenol is not particularly limited, and it can be used in the amount ratio conventionally used in the production of novolak resins. For example, the amount ratio is 0.8 to 1 mol per 1 mol of phenol. Good. The reaction is generally performed by heating the reaction system under reflux, and the generated resin is subjected to treatments such as dehydration, neutralization, washing, and purification, and is recovered as a solid resin component. In the present invention, the phenolic resin is used in an amount of 0.05 to 25% by weight, particularly 0.1 to 15% by weight, based on 100% by weight of the polyester.
It is preferable to blend them in a ratio that results in weight%. If the blend ratio of the phenolic resin is below the above range, the improvement in high-temperature wet heat resistance and impact resistance is insufficient compared to the case where the phenolic resin is within the above range, while if it exceeds the above range, the flavor property decreases. Tend.

(Tocopherol or derivative thereof) Tocopherol (vitamin E) used in the present invention is represented by the following general formula (2)

Embedded image In the above formula (2), R1 = R2 = R3 =
Α-Tocopherol of CH3, R1 = R3 = CH3, R
2 = β-tocopherol of H, R2 = R3 = CH3, R
1 = γ-tocopherol of H, R3 = CH3, R1 = R
Δ-tocopherol where 2 = H can be mentioned.

In the present invention, tocopherol or a derivative thereof is used in an amount of 0.05 to 100% by weight of polyester.
To 3% by weight, particularly preferably 0.1 to 2% by weight. When the amount is less than the above range, the adhesiveness obtained by tocopherol or a derivative thereof, corrosion resistance, high temperature wet heat resistance and the like cannot be sufficiently exhibited, and when the amount is more than the above range, gelation of the polyester may occur. As a result, the smoothness of the coating film is lost, and it tends to be difficult to form a can or a can lid.

In the coating layer of the present invention, a compounding agent for a film known per se, for example, an antiblocking agent such as amorphous silica, a pigment such as titanium dioxide, various antistatic agents, a lubricant, an antioxidant, etc. Can be blended by a known formulation.

The blending of a polyester resin with an ionomer resin or a modifier component such as a phenol resin or a tocopherol can be carried out by dry blending or melt blending depending on the properties of the ionomer resin and the like. The resin may be mixed by a blender, a Henschel mixer, a super mixer, or the like, and supplied directly to the hopper of the extruder. In the latter case, the resin may be kneaded by a single-screw or twin-screw extruder, a kneader, a Banbury mixer, or the like. In any of these cases, the polyester and the ionomer resin are finally blended at a temperature higher than the melting temperature of the polyester. It is also possible to produce a masterbatch containing a relatively high concentration of an ionomer resin or the like, and blend this masterbatch with polyester.

A coating layer in which a polyester resin and an ionomer resin are blended has a temperature of 260 ° C. and a shear rate of 122 seconds.
It is necessary to be kneaded by the above method so that the melt viscosity at ec ^{-1 is} in the range of 2000 to 10000 centipoise, particularly 3000 to 8000 centipoise. In the thermoplastic polyester resin, the more the kneading, the remarkable decrease in viscosity due to thermal decomposition, the intrinsic viscosity of the thermoplastic polyester resin in the coating layer is 0.6 to
1.5 and the ionomer resin is 5 μm
In order to uniformly disperse the thermoplastic polyester resin having the following average particle size in the thermoplastic polyester resin as a matrix, it is particularly important to blend the coating layer so that the melt viscosity of the coating layer is within the above range.

(Metal Plate) As the metal plate used in the present invention, various surface-treated steel plates and light metal plates such as aluminum are used. As a surface-treated steel sheet, a cold-rolled steel sheet is annealed and then subjected to secondary cold rolling, and is subjected to one or more surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment. Can be used. Further, an aluminum-coated steel sheet subjected to aluminum plating, aluminum rolling, or the like is used. As a light metal plate, an aluminum alloy plate is used in addition to a so-called pure aluminum plate. The original 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. The thickness is preferably 10 to 0.30 mm, and in the case of a light metal plate, 0.15 to 0.40 mm.

(Resin-Coated Metal Plate and Production Thereof) The polyester coating layer can be formed on the metal plate by any means, such as extrusion coating, cast film heat bonding, and biaxially stretched film heat bonding. And the like. In the case of the extrusion coating method, a polyester is extruded through a die using an extruder corresponding to the type of the resin layer, and the polyester is extrusion-coated in a molten state on a metal substrate, followed by heat bonding. The thermal adhesion of the polyester composition to the metal substrate is performed by the amount of heat of the molten polyester layer and the amount of heat of the metal plate. A suitable heating temperature for the metal plate is generally 90 to 290 ° C, particularly 100 to 280 ° C.

In the case of a production method using a polyester film, it can be obtained by molding into a film by a T-die method or an inflation film forming method. As the film, an unstretched film formed by a cast molding method in which an extruded film is quenched can be used, and the film is stretched at a stretching temperature, sequentially or simultaneously biaxially stretched, and the stretched film is heat-set to produce a film. A biaxially stretched film can also be used. In the resin-coated metal plate of the present invention, it is possible to adhere the polyester film to the metal material without providing a primer layer between the polyester film and the metal material, but of course excludes providing the primer layer. Instead, an adhesive primer layer such as a phenol-epoxy paint can be provided if desired.

The resin-coated metal plate of the present invention comprises a metal plate surface,
In particular, it is an important feature that the above-mentioned ionomer blend polyester resin layer is provided on the metal surface on the inner surface side of the container, and the thickness of the ionomer blend polyester resin layer is 3 to 40 μm, particularly 5 to 35 μm. It is preferably formed on the surface.

FIG. 1 shows an example of a cross-sectional structure of a resin-coated metal plate of the present invention.
It comprises a metal substrate 2 and an ionomer blend polyester resin layer 3 provided on the inner side when the container is formed. The coating layer 4 is also formed on the outer surface side of the container of the metal base 2, and the coating layer 4 on the outer surface side may be made of an ionomer blend polyester resin, or may be made of another polyester resin. FIG.
Shows another example of the cross-sectional structure of the resin-coated metal plate of the present invention. An ionomer-blend polyester resin layer 3 is provided on the side to be in contact with the metal substrate on the side serving as the inner surface of the container, and a polyester surface layer 5 is provided on the upper surface thereof. Fig. 1
Is the same as

[Resin-Coated Metal Can] The resin-coated metal can of the present invention is manufactured by a conventionally known molding method such that the ionomer-blend polyester resin-coated surface faces the inside of the can. However, since it is preferable to use a seamless can with no side seam, drawing, drawing / deep drawing, drawing / ironing,
It is manufactured by means such as drawing, bending and stretching, and ironing. The side wall portion is stretched by drawing and redrawing of the resin-coated metal plate or is further ironed, thereby forming 20 to 95% of the original thickness of the resin-coated metal plate, particularly 30 to 8%.
It is preferable that the thickness be reduced to 5%.

[Resin-Coated Metal Lid] The resin-coated can lid of the present invention is a conventionally known can lid except that the above-mentioned resin-coated metal plate is formed so that the ionomer-blend polyester resin-coated surface is on the inner side of the can lid. Can be formed by the following method. The shape of the can lid can also adopt a conventionally known shape such as an easy open end provided with a score for forming an opening for discharging contents and a tab for opening.

[0041]

The present invention will be described with reference to the following examples.

[Preparation of Resin-Coated Metal Plate] Examples 2-1
4, With respect to Comparative Examples 1 to 5, the polyester resin shown in Table 1 as a first component and the ionomer resin shown in Table 2 as a second component were put into a twin-screw extruder so as to have the composition shown in Table 3. And melt-knead it through a T-die to a thickness of 30μ.
m was cooled by a cooling roll to obtain a film, which was taken up as a cast film. At this time, the optimum temperature condition suitable for each resin was selected. However, in Example 2, 1 wt% of tocopherol was added as the third component, and in Example 3, 1 wt% of novolak phenol was added as the third component. In Example 5, two twin-screw extruders and a two-layer T-die were used, and the resin shown in Table 3 was used for the lower layer. The polyester resin used for the lower layer was used for the lower layer.
A 6-μm two-layer cast film was prepared.

In Examples 2 to 12 and Comparative Examples 1 to 3, the cast films thus produced were used as TFS steel plates (sheet thickness 0.18 mm, metal chromium amount 120 mg / m ² ,
A chromium hydrated oxide amount of 15 mg / m ² ) was heat-laminated on both sides and immediately cooled with water to obtain a resin-coated metal plate. At this time, the temperature of the metal plate before lamination was set at 15 ° C. higher than the melting point of the polyester resin. The laminating roll temperature is 150 ° C., and the passing speed is 40 m / mi.
n. Was used for lamination.

In Example 13, the thickness was 0.24 mm.
A resin-coated metal plate was obtained in the same manner as in Examples 2 to 12 and Comparative Examples 1 to 3, except that the aluminum alloy plate (A3004H39 material) was used. For Example 14, the plate thickness was 0.25.
A resin-coated metal plate was obtained in the same manner as in Examples 2 to 12 and Comparative Examples 1 to 3, except that an aluminum alloy (A5052H38 material) of mm was used. In Example 1, a TFS steel sheet heated to 250 ° C. (sheet thickness 0.18 mm, metal chromium amount 1
20 mg / m ² , hydrated chromium oxide amount 15 mg / m ² )
Above, a resin having the composition shown in Table 3 was dry-blended and supplied to a φ65 mm extruder equipped with an extrusion coater, and melt-extruded to a thickness of 20 μm on the outer surface side to perform T extrusion.
The FS was coated on one side. Next, as the inner surface side, the same resin component was extruded to a diameter of 65 mm equipped with an extrusion coater.
After being supplied to the extruder, the plate was heated to a temperature 30 ° C. lower than the melting point of the resin, melt-extruded to a thickness of 30 μm, and coated on the other surface to obtain a resin-coated metal plate.

The evaluation method is as follows. [Melt Viscosity] A film was isolated by dissolving metal from a resin-coated metal plate, and then vacuum dried for at least 24 hours to obtain a sample. The melt viscosity was measured at 260 ° C. and 122 sec ⁻¹ using a Capillograph (manufactured by Toyo Seiki Co., Ltd.).

[IV (intrinsic viscosity)] A film is isolated by dissolving a metal from a resin-coated metal plate,
200 ± 0.2 mg of the sample dried under vacuum for 4 hours
After weighing, the mixture was added to 20 ml of a mixed solvent of phenol: 1,1,2,2-tetrachloroethane = 1: 1 (weight ratio), dissolved in an oil bath at 130 ° C. with stirring for about 30 minutes, and cooled to room temperature. Allow to cool. Thereafter, the solution which has reached room temperature is filled into an Ubbelohde viscometer fixed in a constant temperature water bath at 30 ± 0.1 ° C. through a glass filter, and the fall time is measured three times when the temperature is stabilized. The result measured by the above method was substituted into the following equation, and the calculated result was defined as IV (intrinsic viscosity).

(Equation 1)

[Dispersion Particle Size] A sample obtained by dissolving a metal from a resin-coated metal plate to isolate a film, followed by vacuum drying for at least 24 hours is immersed in xylene (temperature 60 ° C.) for 1 minute, Was observed with a scanning electron microscope. The particle size is determined by measuring the area of the particles in the photograph and determining the equivalent circle diameter of the area to at least 100.
The results calculated for the above-mentioned arbitrary grains were averaged.

[Film-forming property] The number of bumps and kogation on the film (15 cm square) after the cast film was formed was measured to evaluate the film-forming property. The evaluation results are shown as follows: 数: Number of lumps and kogation <100 ×: Number of lumps and kogation> 100, and summarized in Table 3.

[Flat Dent ERV] A resin-coated metal plate is
The coated surface to be evaluated is brought into contact with a silicon rubber having a thickness of 3 mm and a hardness of 50 ° in a wet condition at 5 ° C., a steel ball having a diameter of 5/8 inch is placed on the opposite side of the metal plate, and a weight of 1 kg is placed. Was dropped from 40 mm to perform impact overhang processing. Thereafter, the degree of cracking of the resin coating in the impact-processed portion was evaluated by a current value when a voltage of 6.00 V was applied to the processed portion.

[Retort corrosion resistance] After filling with distilled water at 95 ° C, a retort treatment was performed at 135 ° C for 30 minutes, the temperature was returned to room temperature, and distilled water was removed.
In the case of a lid, the corrosion state of the inner surface of the lid was observed. The evaluation results were as follows: ：: No corrosion was observed at all. ×: Abnormality such as corrosion was observed.

[Can Dent Test] After a retort treatment was performed in the same procedure as the retort corrosion resistance test, a 1 / 8-inch diameter steel can The ball was placed, and a 1 kg weight was dropped from 40 mm to perform impact overhang. After processing, distilled water was extracted, and then the degree of cracking of the resin coating on the impact-processed portion was evaluated by a current value when a voltage of 6.00 V was applied to the processed portion.

<Examples 1 to 12> The prepared resin-coated metal plates were subjected to a flat plate dent ERV test. Table 3 summarizes the results. Each of the resin-coated metal sheets had excellent dent resistance. A wax-based lubricant was applied to these resin-coated metal plates, and a disk having a diameter of 140 mm was punched out and drawn to obtain a drawn cup. Next, the drawn cup was bent and stretched twice and ironed to obtain a seamless cup. The characteristics of this seamless cup were as follows. Cup diameter: 52 mm Cup height: 141 mm Thickness of the can wall part 37% of the base plate thickness 69% of the thickness of the part corresponding to the flange part with respect to the base plate thickness
After heat treatment at 20 ° C., the cup is allowed to cool, then trimming of the opening edge, curved surface printing and baking drying,
Neck processing, flange processing, and content 250m
1 was obtained. There was no problem on molding.
Next, it was subjected to a retort treatment test by filling with distilled water and a can dent test. As shown in Table 3, no corrosion was observed in the retort test, and the result of the can dent test was also good. From these results, the seamless cans obtained here were evaluated as being excellent for storing beverages.

Example 13 The prepared resin-coated metal plate was subjected to a flat plate dent ERV test. Table 3 summarizes the results. The dent resistance was excellent. A wax-based lubricant was applied to the resin-coated metal plate, a disk having a diameter of 154 mm was punched out, and a drawing process was performed to obtain a drawn cup. Next, the drawn cup was bent and stretched twice and ironed to obtain a seamless cup. The characteristics of this seamless cup were as follows. Cup diameter: 66 mm Cup height: 127 mm Thickness of the can wall 45% with respect to the base plate thickness 77% of the thickness corresponding to the flange portion with respect to the base plate thickness
After heat treatment at 20 ° C, the cub is allowed to cool, then trimming of the opening edge, curved surface printing and baking drying,
Neck processing, flange processing, 350ml content
A seamless can was obtained. There was no problem on molding. Next, it was subjected to a retort treatment test by filling with distilled water and a can dent test. As shown in Table 3, no corrosion was observed in the retort test, and the result of the can dent test was also good. From these results, the seamless cans obtained here were evaluated as being excellent for storing beverages.

Example 14 The prepared resin-coated metal plate was subjected to a flat plate dent ERV test. Table 3 summarizes the results. The dent resistance was excellent. Next, a lid having a diameter of 68.7 mm was punched out of the resin-coated metal plate so that the resin-coated surface was on the inner surface side of the lid, and then a partial opening type score processing was performed on the outer surface side of the lid (width 22 mm, score remaining thickness 110 μm, A score width of 20 μm), rivet processing, and attachment of an opening tab were performed, and a SOT lid was manufactured. There was no problem on molding. Next, the prepared SOT
Using a lid, a retort treatment test by filling with distilled water was performed. No corrosion was observed in the retort test, and it was evaluated to be excellent as a lid for a metal can.

<Comparative Examples 1 to 3> The prepared resin-coated metal plates were subjected to a flat plate dent ERV test and an adhesion test. Table 3 summarizes the results. The dent resistance was inferior to those of the examples. Also, using this resin-coated metal plate,
Under the same conditions as in Examples 1 to 12, seamless cans were produced. There was no problem on molding. Next, it was subjected to a retort treatment test by filling with distilled water and a can dent test. Table 3
As shown in Table 2, corrosion was observed in the retort test, and the result of the can dent test was also inferior. From these results, it was evaluated that the seamless can obtained here was not suitable for storing beverages.

<Comparative Example 4> When an attempt was made to form a resin as shown in Table 3, many holes were formed in the film, and no subsequent evaluation was performed.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

[Table 3]

[0060]

According to the present invention, the resin-coated metal sheet comprising a coating layer of ionomer blend thermoplastic polyester subjected to the metal plate and the metal plate surface, the temperature of 260 ° C. of the coating layer and a shear rate of 122 sec ^{- 1} has a melt viscosity of 2000 to 10000 centipoise,
The intrinsic viscosity (IV) of the thermoplastic polyester in the coating layer is in the range of 0.6 to 1.5, and the ionomer resin is present as a dispersed phase having an average particle size of 5 μm or less in the coating layer. , Impact resistance (especially dent resistance),
A resin-coated metal plate, a resin-coated metal can, and a metal lid capable of satisfying can performance such as adhesion and flavor, and capable of reducing costs by using a general-purpose polyester resin, can be provided. Further, the resin-coated metal plate of the present invention is excellent in workability and film-forming property capable of coping with high-speed production, and is also excellent in impact resistance and corrosion resistance after retort sterilization.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a cross-sectional structure of a resin-coated metal plate of the present invention.

FIG. 2 is a view showing another example of the cross-sectional structure of the resin-coated metal plate of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 61:10) C08L 61:10) (72) Inventor Akihiko Moroto 1638 Imajuku-Higashicho, Asahi-ku, Yokohama-shi, Kanagawa Prefecture -1 F term (reference) 4F100 AA22 AB01A AB03 AB10 AB31 AH07B AH07C AK33B AK33C AK41B AK41C AK42 AK42J AK70B AK70C AL01 AL05B AL05C BA02 BA03 BA04 BA06 BA07 BA10B BA10C BA13 J01 EGB GBB J01E01B DEB GB JL02 YY00B YY00C 4J002 BB232 CC043 CF061 EL096 GJ00

Claims (7)

[Claims] 1. A resin-coated metal plate comprising a metal plate and a coating layer of an ionomer-blended thermoplastic polyester applied to the surface of the metal plate, wherein the coating layer has a temperature of 260 ° C. and a shear rate of 122 seconds.
^-1 is 2000 to 10,000 centipoise, the intrinsic viscosity (IV) of the thermoplastic polyester in the coating layer is in the range of 0.6 to 1.5, and the average particle size of the ionomer resin in the coating layer is A resin-coated metal plate which is present as a dispersed phase having a diameter of 5 μm or less. 2. The resin-coated metal sheet according to claim 1, wherein the ionomer resin in the coating layer is an ionomer resin containing zinc as a metal species. 3. The thermoplastic polyester (A) in the coating layer
3. The resin-coated metal plate according to claim 1, wherein the ionomer resin (B) is contained in a weight ratio of A: B = 99: 1 to 75:25. 4. 4. The resin-coated metal sheet according to claim 1, wherein a novolak resin of a bifunctional phenol is blended in the coating layer. 5. The resin-coated metal plate according to claim 1, wherein tocopherol or a derivative thereof is blended in the coating layer. 6. The resin-coated metal according to claim 1, wherein the resin-coated plate is formed by drawing, bending or stretching, or ironing so that the coating layer becomes the inner surface of the can. can. 7. A resin-coated metal can lid formed by molding the resin-coated metal plate according to claim 1 such that the coating layer faces the inner surface of the can.