JPS5823219B2 - coated metal container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to containers, coated metal containers such as cans, bags, etc. made of metal coated with a resin mainly composed of polyester resin, and container lids (hereinafter, "containers" also include lids). ).

More specifically, the present invention provides a container formed from a material that has excellent corrosion resistance of a metal substrate, adhesion of a resin coating layer to a metal substrate, a balance of rust prevention and surface properties, and excellent workability, particularly preferably a side surface. This invention relates to a seamless container.

Techniques for coating the surface of metal substrates with resin to prevent the substrate from rusting are well known, but the resins used in these techniques are mainly heat-resistant resins such as epoxy resins, unsaturated polyester resins, and phenolic resins. Curable resins are common.

It is also known to coat a metal substrate with a film of thermoplastic resin such as polyester, polyvinyl chloride, or polyolefin, but these thermoplastic resins have poor adhesion or adhesion to the metal substrate. Currently, a thermosetting compound such as a polyfunctional isocyanate or an epoxy compound is interposed between the metal substrate and the thermoplastic resin as an adhesive or primer.

Among thermoplastic resins, polyester has excellent adhesive strength, heat resistance,
Since polyester resins have many advantages over other resins in terms of flexibility, many proposals have been made regarding polyester resins and compositions thereof.

Examples are (1) polyethylene terephthalate copolymer, (2) polybutylene terephthalate copolymer, (3) polyester and ethylene/vinyl acetate copolymer composition, (4) polyester and polystyrene copolymer. Coalescent compositions and the like are known.

Conventionally, these resins and resins; compositions are made of aluminum, iron,
It has been proposed to directly coat metals such as copper without adhesive or primer coating, but actually coating metals and using them as containers has the following drawbacks.

(1) Adhesive strength to metal is insufficient; increase adhesive strength;
If an attempt is made to remove the resin, the melting point or softening point of the resin decreases and the resin becomes flexible and sticky, so it can be used as an adhesive but cannot be used as a metal coating material.

(2) Even if the adhesive strength with metal is within the practical range for a flat plate,
If it is bent, drawn, or made into a can, the adhesive strength will be insufficient and it will peel off from the metal.

Therefore, a container that can withstand use cannot be made.

(3) Even if the composition has a well-balanced adhesive strength with metal and moldability, if it is made into a container, filled with contents, and subjected to hot water treatment or retort treatment, it will not have heat resistance, so the adhesive strength will be is lowered from metal.

It may peel off, the surface may soften and the contents may adhere to it, or the surface condition may deteriorate.

(4) Barrier properties (property that makes it difficult for gases and liquids to pass through)
, Rust resistance (gas and liquids can pass through it, but corrosive substances are trapped or difficult to pass through).

There is a problem that moisture and chemicals permeate through the resin layer and reach the metal surface, making it easy to rust.

On the other hand, containers with seamless sides, which are typical of metal containers, have conventionally been made by subjecting a metal material such as an aluminum plate or a tin plate to at least one drawing process between a drawing die and a punch, and forming a body with a seamless side surface. The body is formed into a cup with a seamless, integral bottom, and then, if desired, the body is ironed between an ironing die and a punch to stretch and thin the container body! Meat is widely used.

The seamless metal container formed by such drawing or drawing and ironing is then subjected to doming, neck-in or flanging to form a can body that can be secured to a can lid.

A protective coating is then applied to the inner and outer surfaces of the can body and cured.

However, it is generally difficult to apply such a paint to a metal material prior to drawing or ironing because the paint film may be damaged or peeled off during the process.

In particular, in containers for storing liquid materials, even if there is one defect in the coating on the inner surface of the J can, corrosion will progress from this area, resulting in a decrease in flavor and shelf life of the contents.

Therefore, as mentioned above, it is painted after molding.
This method has a significantly lower coating efficiency than the case where paint is applied to a flat plate or coiled metal material.

In addition, in the case of metals that are susceptible to rust due to the influence of oxygen and moisture in the air, such as black plate or various chemically treated steel plates, rust may occur before the protective coating is applied, especially during processing. However, the application of these metal materials to seamless containers is severely limited.

Such limitations in workability are often observed not only in seamless containers but also in bag containers and container lids.

Therefore, metal substrates used as container materials are directly coated with thermoplastic resins that have high adhesion, moldability, and rust prevention properties, and metal containers obtained by processing the same can improve productivity and use. It was highly requested due to the diversification of metals and its non-polluting properties.

The inventors of the present invention have conducted intensive studies on coated metal containers that satisfy these requirements, and have found that if the container is made from a metal substrate coated with a composite resin layer mainly composed of a specific thermoplastic polyester resin, The inventors have discovered that this material has excellent adhesion, moldability, rust prevention, etc., and have arrived at the present invention.

That is, the present invention contains 75 to 100 mol% of A.terephthalic acid (preferably 8
1 to 40 wt%, preferably 5 to 35 wt%) of a polyethylene terecrate resin (0 to 100 mol%),
Terephthalic acid 60-100 mol% (preferably 65-9
30 to 85 wt% (preferably 35 to 80 wt%) of polybutylene terephthalate resin (0 mol%), 10 to 30 wt% (preferably 15 to 25 wt%) of ionomer
t%) (layer A), and B. terephthalic acid 90 to 100 mol% (preferably 95
~100 mol%) polyethylene terephthalate-based or polybutylene terephthalate-based resin 75~
100wt% (preferably 80-100wt%) and ionomer 0-25wt% (preferably 0-20wt%)
and (layer B), and a metal container made of a material in which a foil-like or sheet-like metal substrate is coated with a composite resin layer formed by laminating and.

There are two methods for coating a metal substrate with a composite resin layer: (1) forming a composite film in advance and laminating it directly onto the metal substrate by heat fusion; (2) directly onto the metal substrate;
There are methods such as extrusion lamination of composite film layers, and (3) a method in which powdered resin is coated in multiple layers by electrostatic coating or fluidized dipping.

Furthermore, if necessary, a composite resin layer can be provided on the anchor-coated surface of the metal substrate.

In the present invention, from the viewpoint of productivity and manufacturing cost, (1)
Methods (2) and (2) are preferred.

Therefore, the detailed description of the present invention will be given using the coating method (1) as a representative example, but the present invention is not necessarily limited to the method (1).

The first feature of the present invention lies in the coating resin composition and the structure of the composite layer.

That is, the polyethylene terephthalate resin used for layer A of the present invention is 75 to 100 mol% of the dicarboxylic acid component.
is terephthalic acid.

As the remaining dicarboxylic acid of terephthalic acid, aromatic and aliphatic dicarboxylic acids such as isophthalic acid, sebacic acid, adipic acid, and azelaic acid are used in an amount of 0 to 25 mol%, preferably 0 to 20 mol%.

Isophthalic acid is particularly preferred in terms of heat sealability, adhesiveness, and film stiffness.

Ethylene glycol is used as the diol component, but
Other diols, such as diethylene glycol, butanediol, 1,4-cyclohexane dimetatool,
The amount of 6-hexanediol etc. is within the range (preferably from 0 to
20 mol%) can also be used.

Specific examples of these polyethylene terephthalate resins include polyethylene terephthalate (PET) and polyethylene terephthalate isophthalate (PET/I).
, polyethylene terephthalate sebacate (PET/
/S), polyethylene terephthalate adipate (P
ET/A).

If the terephthalic acid content is less than 75 mol%, the composite film has no stiffness and is easily softened, resulting in wrinkles when laminated to a metal substrate, a decrease in the film width during lamination, and problems with adhesive bonding. This causes a decrease in barrier properties and rust prevention properties.

60 to 100 mol % of the dicarboxylic acid component of the polybutylene ethylene terephthalate-1 type resin used in layer A is terephthal.

The remaining dicarboxylic acid of terephthalic acid is 0 to 40 mol% of dicarboxylic acids such as isophthalic acid, sebacic acid, adipic acid, and azelaic acid, especially isophthalic acid 10 to 3% by mole.
A content of 5 mol % is preferable in terms of film flexibility, adhesive strength, and film formability.

1,4-butanediol is used as the diol component, but other diol components such as ethylene glycol, diethylene glycol, neopentyl glycol, It is also possible to use copolymerized products within a range (preferably 0 to 20 mol%) that does not impair the properties of the resin. ), polybutylene terephthalate sebacate (PBT/S), polybutylene terephthalate adipate (PBT/A), polybutylene ethylene terephthalate, polybutylene ethylene terephthalate isophthalate, and the like.

If the terephthalic acid content is less than 60 mol %, the resin will have a low melting point, which will cause chips to fuse together when the resin is dried, causing trouble during melt extrusion.

In addition, since the slipperiness of the surface of the A layer deteriorates, wrinkles occur when the film is wound up, and the winding becomes tight, resulting in a significant loss of flatness.

Furthermore, there is a drawback that blocking occurs when coated metal substrates are piled up.

The ionomer used for the A layer and B layer of the present invention is an ionomer containing an α-olefin and a monovalent or divalent metal ion.

It is a copolymer with an ionic salt of β-unsaturated carboxylic acid.

Specific examples include the carboxyl group of a copolymer of ethylene and an α,β-unsaturated carboxylic acid such as acrylic acid or methacrylic acid, or a copolymer of ethylene and an unsaturated dicarboxylic acid such as maleic acid or itaconic acid. It is a polymer in which part or all of is neutralized with a mono- or divalent metal such as sodium, potassium, lithium, zinc, magnesium, or calcium.

Furthermore, a product obtained by esterifying a portion of the remaining carboxyl groups with a lower alcohol can also be used.

As the metal, zinc is particularly preferred in terms of the slipperiness, scratch resistance, barrier properties, and rust prevention properties of the resin layer.

The content of the copolymer component having a carboxyl group in the ionomer before neutralization with metal is 1 to 20 mol%, preferably 2 to 15 mol%.

The degree of neutralization of carboxyl groups is 15 to 100%, preferably 20 to 80%, more preferably 30 to 70% in view of the melt extrudability of the composition.

Typical examples of these ionomers include copolymers of ethylene and acrylic acid or methacrylic acid (2 to 15 mol% of the copolymerized component having carboxyl groups), and metals such as sodium and zinc that account for 30 to 70% of carboxyl groups. can be neutralized.

The content of the copolymer component having a carboxyl group and the degree of neutralization are closely related to the film-forming properties, flexibility, and rust prevention properties of the composition.

If the content of the copolymer component having a carboxyl group is less than 1 mol %, the flexibility and rust prevention properties will be poor, and if it exceeds 20 mol %, the heat resistance and film forming properties will be poor.

If the degree of neutralization is less than 15%, the rust prevention properties will be poor.

Further, even if the degree of neutralization is 80% or more, there will be no problem with rust prevention, but it is necessary to increase the melt extrusion temperature of the composition.

Therefore, there is less substantial hindrance, but the extrusion temperature range is narrowed.

As these ionomers, those commercially available under the trade name "Surlyn" (manufactured by DuPont) can be used.

The composition constituting layer A needs to be blended in a predetermined amount in order to achieve all of the sliding properties, lamination, adhesion, moldability, and rust prevention properties of the composite film.

If the amount of polyethylene terephthalate resin is less than 1 wt %, the film will have poor slipperiness and insufficient adhesive strength.

When it exceeds 40 wt%, adhesive strength decreases, and moldability and rust prevention properties are impaired.

If the content of the polybutylene terephthalate resin is less than 30 wt%, the adhesive strength will decrease, and the moldability and rust prevention properties will deteriorate.

If it exceeds 85 wt%, the slipperiness of the film will deteriorate and the rust prevention properties will deteriorate.

If the ionomer content is less than 10 wt%, slipperiness and rust prevention properties will be reduced.

If it exceeds 30 wt%, the dispersion state of the composition becomes unstable and it is very easy to tear, which impairs molding processability, and also causes deterioration in blocking, lamination properties, and heat resistance.

The polyester forming layer B has a terephthalic acid content of 90 to 90%.
Polyethylene terephthalate system consisting of 100 mol%,
Alternatively, it is a polybutylene lenticulate resin.

The reason why the terephthalic acid content is required to be 90 mol % or more is from the viewpoint of film stiffness, lamination properties, barrier properties, and rust prevention properties.

All of the diol components that can be used other than the remaining dicarboxylic acid and ethylene glycol are the same as those of the polyethylene terrecrate resin of layer A.

The blending ratio is preferably within the range of 75 to 100 wt% from the viewpoints of slipperiness, blocking, barrier properties, rust prevention, and heat resistance.

The polybutylene terephthalic acid used in layer B preferably has a terephthalic acid content of 95 mol % or more, particularly 100 mol %, from the viewpoints of stiffness, lamination properties, barrier properties, and rust prevention properties of the composite film.

All of the diol components that can be used other than the remaining dicarboxylic acid and ethylene glycol are the same as those of the polybutylene ethylene reflex resin of layer A.

The blending ratio ranges from 90 to 100 wt%, which has barrier properties.
Especially excellent in terms of rust prevention and heat resistance.

The blending ratio of the ionomer in layer B is 0 to 25 wt%.

In the case of a container that undergoes relatively little deformation during molding, 0wt% ionomer is preferable in terms of rust prevention.

However, in the case of containers with a large drawing ratio, the addition of an ionomer improves the drawing processability and also improves the rust prevention properties.

However, if the blending ratio exceeds 25 wt%, the surface of layer B will become rough, which is not preferable from the standpoint of rust prevention.

The polyester of layer B is composed of polyethylene terrescrate resin or polybutylene terephrate resin as described above, but the other polyester resin may be mixed within the range that does not impede the function of layer B. I can't hold back.

In addition, layers A and B may contain antioxidants, heat stabilizers, ultraviolet absorbers, viscosity modifiers, plasticizers, nucleating agents, inorganic fine particles, organic lubricants, metal powders such as aluminum and zinc, pigments, etc., as necessary. Additives can be dispersed and blended.

As the inorganic fine particles, fine particles of silicon dioxide, aluminum silicate, magnesium silicate, etc., zinc oxide, titanium oxide, etc. can be used.

Further, for the same purpose as the above-mentioned additives, a known resin may be added within a range not exceeding 20 wt % based on the total amount of the composition.

The structure of the composite resin layer of the present invention is usually a two-layer film of A/B.

Both the A layer and the B layer have adhesiveness and antirust properties, but the A layer has superior adhesiveness to metal.

Furthermore, the B layer is superior to the A layer in terms of moldability, barrier properties, and rust prevention properties.

In addition, when considering rust prevention in particular, B/A/B/A...
It can also be used in the form of a B/A multilayer composite film.

Therefore, in the coated metal plate of the present invention, it is preferable that the A layer has a metal surface as in the configuration (B/A/metal).

The thickness of the composite resin layer of the present invention and the thickness ratio of A:B vary depending on the purpose of use of the container, but the thickness is generally 5μ to 5μ.
17 nm1, preferably 10 to 500 microns, and particularly preferably 20 to 60 microns for containers with seamless sides.

The thickness ratio of layer A and layer B can be appropriately selected depending on the purpose of use of the container, but it is A:B layer 1:0.1-20, preferably 1:0.5-10.

Regarding the use of the composite resin layer in the present invention, in the case of the combination (B layer/metal), the adhesive strength is insufficient and the moldability is poor.

In particular, when a container is made by deep drawing, the B layer is likely to peel off, resulting in a decrease in rust prevention.

Although the combination of (A layer/metal) has a fairly good molding process, there are still some shortcomings.

For example, if the drawing speed is increased during deep drawing, the material will tend to stick to the mold or the surface will become rough.

The rust prevention properties of containers may be able to withstand for a short period of time if they are less corrosive, but if acidic foods or boiled fish meat are canned, the rust prevention properties may be insufficient and the cans may deteriorate. It will rust.

However, with the combination of the present invention, moldability is good, deep drawing can be performed at high speed, and there is no peeling of the resin layer.

Furthermore, when used in cans, it can withstand acidic foods, boiled fish, etc., and has excellent rust prevention properties.

The metal substrates used in the present invention include various chemically treated steel sheets such as phosphate-treated steel sheets and chromic acid-treated steel sheets, electrolytic chromic acid-treated steel sheets, black plates (raw steel sheets) without surface treatment, tin, zinc, etc. Examples include plated steel, aluminum, and copper.

In particular, when various steel plates are used, raw steel plates, chemical conversion treated steel plates, and electrolytic chromic acid treated steel plates are particularly preferred in terms of adhesive strength and workability.

The second feature of the present invention is that the coated metal substrate has excellent drawing and ironing workability, and a container with seamless sides can be easily made by a conventionally known method, and is better than conventional containers with seamless sides. It has excellent adhesive strength and rust prevention properties.

An example of the method for manufacturing the product of the present invention will be described below.

When punching discs, circles, rectangles, squares, etc. into arbitrary shapes from coated metal substrates, in the case of polygonal plates, cut corners to prevent the material from breaking.

You can add an R to the part.

Next, drawing is performed using a drawing die and a punch to form a shallowly drawn cup-shaped product.

Usually the aperture ratio is 1.1 to 3.0, preferably 1.2 to 2.8
be taken in.

Therefore, this cup-shaped molded product can be used as a shallow-drawn container with seamless sides.

However, deep-drawn containers with high side walls compared to the bottom are
The cup obtained in the stage drawing process is redrawn again between a redrawing die with a smaller diameter and a redrawing punch to produce a deep drawn cup-shaped container.

At this time, you can also add a slight squeeze by adjusting the clearance between the drawing die and punch.

The deep-drawn cup is further ironed between an ironing punch and an ironing die.

The ironing rate in this case can be changed by adjusting the clearance between the punch and die, but it is usually 10 to 50%.
It is desirable that it be within the range of .

The metal substrate used in such a method typically has a thickness of 3.
Plates or foils with a thickness of μ to 1 mm, especially 5 μ to 0.5 mm, are used.

In addition, the container lid is manufactured by punching the coated metal substrate into a shape such as a disk, and then drawing, pressing, beading, rolling, scoring, etc. to produce a screw cap, paper vacuum cap, etc. It is formed into the shape of a container lid known per se, such as an anchor cap, a honeycomb cap, a crown cap, a beer-proof cap, a beer-off cap, or a can end.

A third feature of the invention is that if the coated metal container requires heat sealing or adhesive sections, these can be formed from the same resin composite layer as the surface coating material.

In other words, since the coating resin layer used in the present invention itself has excellent heat-sealability when heated, for example, after forming the main body of a can from a coated metal substrate and forming this main body into a roll shape, the end portion is Overlap and heat seal,
The can container can then be easily manufactured by rolling or heat sealing the lid.

Similarly, it is also possible to manufacture bag-like containers, so-called flexible pouches, by taking advantage of the heat-sealing properties. An alternative method of stacking two flexible sheets facing each other and thermally bonding their peripheral portions is to fold one sheet back and thermally bonding the opposing peripheral portions.

Note that during heat sealing, a thermosetting adhesive such as another epoxy resin or isocyanate may be applied to the bonded portion.

The fourth feature of the present invention is that, as already mentioned in the resin composition and composite layer, the metal container manufactured by such intense molding or heat sealing can withstand hot water treatment and retort treatment, and can hold the contents. The advantage is that rust does not occur on the metal substrate.

In the metal container of the present invention, surface treatments such as top coating and printing can be performed on the composite resin layer at any stage before or after molding.

The coated metal containers of the present invention are food cans, beverage cans, miscellaneous cans such as oil cans, confectionery cans, coffee cans, cosmetic cans such as tea cans,
It has excellent properties and is extremely useful for applications such as moisture-proof vacuum packs for packaging sweets, coffee, etc., retort pouch containers for processed foods such as curry and beef stew, lids for containers, and pressure-resistant containers for aerosols, etc. .

The physical property measurement method and evaluation method in the present invention are as follows.

(1) Can manufacturing method A low carbon twice cold rolled raw steel plate with a thickness of 0.17 mm degreased with trichlorethylene and a coating film are laminated 130
Temporary bonding of the laminate is carried out using a roll press at ~150°C.

Next, main adhesion is performed by heating in an oven at 240 to 280°C for 90 seconds, and cooling with water to obtain a steel plate coated on one or both sides.

This coated steel plate was punched to a diameter of 112 mm and drawn (
Aperture ratio 2.1), diameter 53mm, height 40mm
Make a can.

Further, a low carbon double cold rolled raw steel plate having a thickness of 0.21 m7IL was coated in the same manner and molded to make a can lid.

The evaluation of can-making workability is that there are no defects such as wrinkles on the steel sheet or scratches on the film.

△: Partial wrinkles on the steel plate or roughness on the film surface.

×: The steel plate has many wrinkles and peeling of the film is observed.

(2) Tort processing and actual can test The canned container is trimmed and flanged, filled with foods such as tuna soy sauce seasoned and boiled salmon, and the can lid is double-sealed and heated at 120℃ and 90℃. Canned food was made by retort processing.

Immediately after retorting and after storage at 50° C. for 6 months, the cans were opened and the state of rusting and adhesive strength of the resin layer were evaluated as follows.

Rust prevention ◎: No gold metal discoloration or rusting observed.

○: Slight discoloration, pinhole-like discoloration, and a few rust spots were observed at the interface between the liquid phase and gas phase of the contents.

△: Some pinhole-like rust is observed. ×: Rust occurs on the entire surface.

Adhesive strength ◎: Strong adhesion even after cross-cutting.

■ = No peeling, but adhesive strength slightly decreased due to cross-cutting.

△: The film peels off when a cross cut is made.

×: Separation of the film is observed.

Example 1 Intrinsic viscosity 0 measured in 0-chlorophenol at 25°C
．． 65 PET, 1.0 PBT/I (terephthalic acid/isophthalic acid molar ratio 65/35), and "Surlyn" (type 1706, melt index o, 7 g
The A-layer and B-layer resins were each pelletized at 270° C. using a Berequiser with a diameter of 40 mm at the compounding ratio shown in Table 1.

The B-layer resin was then transferred to a 40mm extruder at 275°C.
The A-layer resins were each supplied to a 40zm$ extruder at 270°C, laminated to A/B with a nozzle (270°C), extruded so that the B layer was on the cast drum surface (surface temperature 55°C), and the thickness was adjusted. A film with a thickness of 50μ was made.

The thickness ratio was A:13=1:1.5.

For comparison, 50μ films containing only the A layer and only the B layer were formed at 270°C.

The composite film /f61-8 used in the present invention has good film stiffness and slipperiness, and was coated on both sides of a 0.17 mm thick low carbon twice cold rolled raw steel plate so that the A layer was in contact with it.

During the coating process, we were able to create a film with no wrinkles or air bubbles, and no surface defects.

When the coated steel plate was used to make cans (drawing ratio: 2.1), clean cans were made without any trouble.

Boiled salmon was filled into these cans, sealed and retorted.

The product of the present invention exhibited good rust prevention, properties, and adhesive strength, not only immediately after retorting, but also in an accelerated storage test at 50° C. for 6 months, and showed good results with no deterioration in flavor.

On the other hand, //69 to 13, which are not covered by the present invention, had the following drawbacks.

In No. 49, the surface of the B layer was noticeably rough, the barrier properties of the B layer were greatly reduced during can making, and the inner surface of the can was blackened.

/l610 has insufficient adhesive strength in the A layer, so the adhesive strength decreases significantly during severe drawing processing, and the film partially peels off during retort processing.

//6.11 also has a low adhesive strength like /l610 because the A layer contains a lot of PET.

/16], 2 is a can made of only A layer,
Cans can be made, but since there is no B layer, the barrier properties and rust prevention properties (the inner surface of the can turned black) are poor, so it is unsuitable for use in can containers.

Since 413 did not have the A layer, the adhesive strength was insufficient, and partial peeling of the film was observed during drawing.

Example 2 PET1 and PET/I with intrinsic viscosity 0.63 (terephthalic acid 95.90.80 mol%, intrinsic viscosity 0.65
, 0.66.0.66), ``Sarlin'' 1706, PB
T/I (terephthalic acid 80.65 mol%, intrinsic viscosity 1
．． 20, 1.30), PBT (intrinsic viscosity 1.00)
The compositions of each layer A and B were pelletized using a compounding ratio shown in Table 2.

Next, a film was formed in the same manner as in Example 1 to form a film having a thickness of 30 μm and having an A/B composition and an A:B ratio of 3.

This composite film is coated on both sides of a mildly treated electrolytic chromic acid treated steel plate with a thickness of 0.171 m (temporary adhesion 13
(0°C, main adhesion 270°C), and deep drawing was performed in the same manner as in Example 1 to produce a can with a drawing ratio of 1.8.

Can lids were also made from the same material, filled with tuna and soy sauce flavoring, and retorted using conventional methods to produce canned goods.

/1614-18 according to the present invention also showed good results in the canned storage acceleration test.

On the other hand, since the PET/I and PBT/I used for the B layer are not suitable for Al1°20, which is outside the scope of the present invention, the surface becomes rough during can manufacturing, and the steel plate wrinkles in the upper part of the can.

Furthermore, when canned, the barrier properties were insufficient and rusting was observed.

Example 3 The polyester resin used in Example 1 was used, the A layer had the composition shown in Table 3, and the B layer had the composition of PET/"Surlyn" 85/15, thickness 50μ, A:B=1:1. A composite film with an A/B configuration was made.

However, as 'Sasan', 1652 (Tart index 5 g/10 mm, Zn type) and 17
06 was used at a ratio of 1:1.

Cans and can lids were made in the same manner as in Example 1, and the cans were filled with boiled salmon.

As is clear from Table 3, the product of the present invention showed good results in the actual can test.

/1624 does not contain Surlyn in the A layer, so wrinkles may occur on the steel plate during can manufacturing, and when used for canning,
Black rust occurred.

A625 could not be used as a container because peeling of the film was observed on the top of the can, which had a large degree of deformation.

Example 4 PET (intrinsic viscosity 0.63), PET/I (terefucuric acid 85.70 mol%, intrinsic viscosity 0.67, 0.66
), PBT/I (terephthalic acid copolymerization ratio is 5, respectively)
5°60.65.85 mol%, intrinsic viscosity 1.10,1.
15゜1.28, 1.27), ゛ゞSasan''17
The composition of layer A in Table 4 was pelletized using each of the polymers shown in Table 4.

B layer is PET@viscosity 0.68, titanium oxide 30
A composition containing Surlyn 1706 at a ratio of 9515 was prepared.

The compositions of layer A and layer B are each supplied to two extruders,
A two-layer film with a thickness of 40μ was produced in the same manner as in Example 1 (
A:B layer 1:1.5) was formed into a film.

The A layer side of this composite film is thermally bonded (temporary adhesion 1
A coated steel plate was prepared by bonding at 40°C and 280°C for main adhesion.

Next, a can was made in the same manner as in Example 1 so that the composite film surface was on the inside, and a can with a drawing ratio of 2.0 and a can lid were made.

Cans were made by filling with boiled salmon and performing retort processing.

A and Nos. 26 to 28 of the present invention were highly evaluated for their good can-manufacturing properties, rust prevention properties, and adhesive strength.

On the other hand, /4629.30 is the PET used * */1. + Because the copolymerization ratio of PBT/I was not appropriate, wrinkles tended to appear at the top of the can during can manufacturing.

Accelerated storage tests revealed that black rust had formed on the inner surface, reducing adhesive strength.

Example 5 The composition of the composite film of Experimental Form 2 of Example 1 was /162 except that 1.8 wt% of aluminum fine powder was added to the A layer.
The same composite film //631 was formed.

Side A of this film was coated on both sides of the electrolytic chromic acid treated steel plate used in Example 2 to produce a can with a drawing ratio of 2.1 and a can lid.

The can making property was good (◎), and the cans were filled with tuna seasoned with tomato dressing mainly consisting of tomato puree and vinegar and subjected to retort processing.

Despite being a highly acidic food, no rust was observed even after 6 months in a real can test at 50°C.
◎), there was good adhesion (◎), and there was no deterioration in flavor.

For comparison, 1. O0m9/d m
When compared with cans made in the same way by applying 2 coats and baking and drawing, it was found that rust occurred (×) 1 after 6 months in actual can test at 50°C.
It was so intense that it even put a hole in the can.

Thus, the product of the present invention was found to be a container with excellent acid resistance.

Example 6 The composite film of layer A 2, 7.9 of Example 1 was made to have a thickness of 0.2
Both sides of a 4 mm raw steel plate were coated with layer A so as to be in contact with each other (temporary adhesion at 150°C, final adhesion at 280°C).

Furthermore, for comparison, epoxy/urea paint was applied to both sides of a raw steel plate and baked to give a coating strength of 55 Tvdm.

Using this material, a scree cap with a diameter of 73 mm and a height of 18 mm was molded.

Fill each cap with mayonnaise and tomato puree, cover the surface with a glass plate, and
After storage for 2 weeks at °C, the state of rust was observed (Table 5).

It was found that the product of the present invention did not cause the film to peel off from the metal during molding, had good moldability, and had sufficient rust prevention properties.

On the other hand, in layer A, 9, rust was observed on the helical part, and the conventional paint cap had rust on the entire surface.

Claims (1)

[Claims] 1 polyethylene terephthalic acid resin consisting of 75 to 100 mol% of A. terephthalic acid 1 to 4.0 wt%,
A layer consisting of 30 to 85 wt% of a polybutylene terephthalic acid resin consisting of 60 to 100 mol% of terephthalic acid, and 10 to 30 wt% of an ionomer, and a polyethylene terephthalate type resin consisting of 90 to 100 mol% of B.terephthalic acid, or Polybutylene terephthalate resin 75
A metal container made of a material in which a foil-like or sheet-like metal substrate is coated with a composite resin layer formed by laminating a layer consisting of ~100wt% of ionomer and 0~25wt% of an ionomer.