JP3343424B2 - Resin-coated metal sheet for drawn ironing can and drawn iron can - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated metal plate for a drawn and ironed can and a drawn and ironed can made of the resin-coated metal plate, and more particularly to a resin-coated metal plate for a drawn and ironed can formed by laminating a specific resin layer. And a drawn ironing can made of the resin-coated metal plate.

[0002]

BACKGROUND OF THE INVENTION Conventionally, a drawn ironing can (hereinafter referred to as a DI can) obtained by drawing and ironing a steel plate such as a tin plate or an aluminum plate or by drawing is seamless and has excellent physical properties. Widely used.

[0003] In such a DI can, a resin layer is provided on the inner surface side of the can in order to prevent a decrease in taste due to metal elution from a metal plate, a decrease in flavor, deterioration of contents and generation of pinholes. Sometimes. Examples of such a can having a resin layer provided on the inner surface side thereof and a resin-coated metal plate capable of forming such a can include, for example, JP-A-51-130.
No. 647 proposes a steel sheet coated with a saturated polyester layer and a container obtained therefrom. JP-A-1-180336 proposes a steel sheet coated with a polybutylene terephthalate layer, which is disclosed in JP-A-1-192545, JP-A-2-57339, and JP-A-3-10835. Has proposed a steel sheet coated with a specific saturated copolyester layer and a container obtained therefrom.

By the way, a coating resin used for a steel plate for drawing and ironing is required to have excellent formability capable of following the drawing and ironing process, and also to have excellent adhesion so as not to peel off from the steel plate. . Further, this resin is required to have excellent impact resistance so that it can withstand impacts during canning, canning and transportation. In addition, it is required that there be no pinholes that cause corrosion during storage, and that properties such as not affecting the taste of the beverage, that is, being excellent in flavor, are provided.

[0005] However, the resin coated on the conventional steel plate for cans does not always satisfy such a requirement. For example, pinholes were sometimes formed in the resin film during drawing and ironing. Further, after the can was made, the can heated in the steps of drying, printing, baking and the like sometimes had a reduced impact resistance.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has excellent drawability and ironing formability, excellent adhesion to a metal plate, excellent impact resistance, and pinholes. It is an object of the present invention to provide a resin-coated metal plate for a drawn and ironed can, on which a resin layer having characteristics such as excellent flavor property is laminated, and a drawn and ironed can made of such a resin-coated metal plate.

[0007]

SUMMARY OF THE INVENTION A resin-coated metal plate for a drawn and ironed can according to the present invention comprises a metal plate and a resin film provided on one or both surfaces of the metal plate. When the dicarboxylic acid component is derived from an acid and a dihydroxy compound and the dicarboxylic acid component is 100 mol%, the dicarboxylic acid component is a crystalline saturated polyester resin layer composed of 99 to 85 mol% of terephthalic acid and 1 to 15 mol% of isophthalic acid. [B] derived from a dicarboxylic acid and a dihydroxy compound, wherein the dicarboxylic acid component is composed of terephthalic acid, and the dihydroxy component is 99 to 70 mol% of ethylene glycol, 1 to 30 mol% of cyclohexanedimethanol and 0 to 5 mol of diethylene glycol. % And an amorphous saturated polyester resin layer of [B]
An amorphous saturated polyester resin layer is laminated so as to be in contact with the metal plate , and the [A] layer provided on the metal plate
And the resin film consisting of the layer [B] are substantially unoriented.
And an amorphous state .

[A] a crystalline saturated polyester resin layer,
[B] The amorphous saturated polyester resin layer preferably has a thickness ratio of [A] layer: [B] layer = 3: 1 to 1: 3.

[0009] The drawn and ironed can according to the present invention is formed from the above resin-coated metal plate.

[0010]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, a resin-coated metal plate for a drawn and ironed can according to the present invention and a drawn and ironed can made of the resin-coated metal plate will be described.

The resin-coated metal plate for a drawn and ironed can according to the present invention comprises a metal plate and a resin film provided on one surface of the metal plate. In the present invention, conventionally known metals generally used for cans are widely used as the metal plate. Specifically, a steel plate (tin) whose surface is plated with Sn (tin) by a known method, tin An uncoated steel sheet (tin-free steel, electrolytic chromic acid-treated steel sheet) or an aluminum sheet is used.

The metal plate has a thickness of usually 0.01 to 5
mm, preferably 0.1 to 2 mm. On one side or both sides of this metal plate, two types of [A] crystalline saturated polyester resin layer and [B] amorphous saturated polyester resin layer
A resin coating consisting of a layer is formed by laminating an amorphous saturated polyester resin layer [B] so as to be in contact with the metal plate.

The [A] and [B] saturated polyester resins used in the present invention are formed from structural units derived from a dicarboxylic acid and a dihydroxy compound. [A] The dicarboxylic acid component forming the crystalline saturated polyester resin used in the present invention is 99 to 85 mol%, preferably 97 to 87 mol% of terephthalic acid when the dicarboxylic acid component is 100 mol%. And isophthalic acid 1
~ 15 mol%, preferably 3 ~ 13 mol%.

[A] Examples of the dihydroxy component forming the crystalline saturated polyester resin include ethylene glycol, trimethylene glycol (propylene glycol), tetramethylene glycol, pentamethylene glycol, diethylene glycol, and triethylene glycol. And other aliphatic dihydroxy compounds.

The [A] crystalline saturated polyester resin used in the present invention has a glass transition temperature (Tg) of usually 50.
To 120 ° C., preferably 60 to 100 ° C., the low-temperature crystallization temperature (Tc) is usually 130 to 210 ° C., preferably 140 to 200 ° C., and the crystal melting temperature (Tm) is
It is usually from 210 to 265 ° C, preferably from 220 to 260 ° C.

The [A] crystalline saturated polyester resin used in the present invention preferably has a crystallinity of 5 to 75%, preferably 10 to 60%, as measured by an X-ray diffraction method.

The film formed from such a crystalline saturated polyester resin (A) hardly adsorbs terpene odor. The amorphous saturated polyester resin [B] used in the present invention is a resin having a crystallinity of 20% or less, preferably 15% or less as measured by an X-ray diffraction method.

[B] In the amorphous saturated polyester resin used in the present invention, the dicarboxylic acid component is terephthalic acid, and the dihydroxy component is ethylene glycol 9
9-70 mol%, cyclohexanedimethanol 1-30
Mol% and 0-5 mol% of diethylene glycol. The dihydroxy component is preferably from 93 to 70 mol% of ethylene glycol and from 7 to 70% of cyclohexanedimethanol.
30 mol% and 0-5 mol% of diethylene glycol,
More preferably, it is composed of 85 to 70 mol% of ethylene glycol, 15 to 30 mol% of cyclohexanedimethanol and 0 to 5 mol% of diethylene glycol.

The amorphous saturated polyester resin [B] used in the present invention has a glass transition temperature (Tg) of usually 50.
To 120 ° C, preferably 60 to 100 ° C.

The saturated polyesters [A] and [B] used in the present invention as described above may be trimesic acid, pyromellitic acid, trimethylolethane, trimethylolpropane, trimethylolmethane as long as the object of the invention is not impaired. And a small amount of a structural unit derived from a polyfunctional compound such as pentaerythritol, for example, 2 mol% or less.

The saturated polyesters [A] and [B] used in the present invention are substantially linear, which is confirmed by the dissolution of the saturated polyester in o-chlorophenol.

[0022] The saturated polyesters [A] and [B] used in the present invention are prepared in o-chlorophenol at 25 ° C.
The intrinsic viscosity [η] measured in the above is usually 0.5 to
It is 1.4 dl / g, preferably 0.5 to 1.0 dl / g, more preferably 0.6 to 1.0 dl / g.

A saturated polyester having such an intrinsic viscosity [η] is preferable because it has excellent melt moldability and drawability, and has excellent mechanical strength such as impact resistance.

In the present invention, the resin film laminated on the metal plate is composed of two types of the above [A] crystalline saturated polyester resin layer and [B] amorphous saturated polyester resin layer.
The [B] amorphous saturated polyester resin layer is laminated so as to be in contact with the metal plate.

The thickness of the resin layer thus laminated is 2
The total of the layers is usually 5 to 500 μm, preferably 10 to 1 μm.
00 μm, particularly preferably 20 to 60 μm. The thickness ratio of the two layers [A] crystalline saturated polyester resin layer and [B] amorphous saturated polyester resin layer is [A]
Layer: [B] layer = 3: 1 to 1: 3 is preferred.

It is preferable that the resin coating composed of the layer [A] and the layer [B] provided on the metal plate be substantially unoriented and in an amorphous state. As described above, the resin-coated metal plate for drawn and ironed cans according to the present invention is formed from the specific polyester layers [A] and [B], and is excellent in drawn and ironed workability.

The above resin coating [A],
[B] If any one of the layers is oriented by stretching or the like, it may not follow the drawing and ironing process, and the resin layer may be broken, and these layers [A] and [B] may be other than the above. If it is formed from a resin, it may not be possible to obtain a good drawn and ironed can. For example, when the layer [A] is formed from homopolyethylene terephthalate, a large number of blisters may be generated in the obtained drawn and ironed can (can bottom), and the flavor may have poor adsorption characteristics.
Further, when this [A] layer is formed from a copolymerized polyester containing an isophthalic acid component in an amount exceeding 15 mol, the punch is inferior in punching during drawing and ironing, and a good drawn iron can cannot be obtained. is there. Further, when the layer [B] is formed from a copolymerized polyester containing an isophthalic acid component in an amount of 20 mol%, and when the layer [A] is homopolyethylene terephthalate, the adhesion between the resin film and the can is poor. Blisters may be formed at the bottom, and this [A] layer contains 10% by mole of isophthalic acid component.
When the copolymerized polyester is contained in the above amount, the adhesiveness is excellent, but blisters are easily generated.

In the present invention, the resin layers [A] and [B] as described above contain additives such as weather-resistant stabilizers, lubricants, heat stabilizers, and impact modifiers, if necessary. Is also good. When forming the resin layers [A] and [B] as described below, these additives may be used after forming a master batch from these additives and the resin [A] or [B] in advance. it can.

The above-described resin-coated metal plate for a drawn and ironed can according to the present invention is manufactured, for example, as follows. (1) [A] A crystalline saturated polyester resin and [B] an amorphous saturated polyester resin are formed on a metal plate by a two-layer extrusion T-die so that the [B] amorphous saturated polyester resin layer is in contact with the metal plate. Extrude simultaneously.

(2) Once a film composed of [A] a crystalline saturated polyester resin layer and [B] an amorphous saturated polyester resin layer is formed, this film and a metal plate are bonded to [B].
The amorphous saturated polyester resin layer is bonded so as to be in contact with the metal plate.

(3) It is also possible to form a [B] amorphous saturated polyester resin layer on a metal plate and then form an [A] crystalline saturated polyester resin layer on the [B] layer.
When coating the resin layer on the metal plate as described above,
It is preferable that the resin film extruded in a molten state from the extruder and coated on the metal plate be rapidly cooled.

Of these methods, the method (1), which is simultaneously extruded by a two-layer extrusion T-die, is excellent in terms of production cost, and the resin-coated metal plate obtained by this method has a high quality such as no pinholes. This is preferable because ironing cans are easily obtained.

It should be noted that the film is once formed and then laminated.
The method of (2) increases the manufacturing cost as compared with the method of (1) and the obtained resin-coated metal plate may be inferior to the result of the pinhole test, and the method of (3) requires a specific film thickness ratio. May not be able to obtain a uniform two-layer coating having
The adhesion between the layer [A] and the layer [B] may be poor or foreign matter (dust) may be mixed.

The resin-coated metal plate according to the present invention comprises, as described above, a metal plate and, on one surface thereof, [A] a crystalline saturated polyester resin layer and [B] an amorphous saturated polyester resin layer. A film having a thickness ratio as described above and [B] an amorphous saturated polyester resin layer laminated on a metal plate so as to be in contact with the metal plate, and having excellent impact resistance and formability, especially draw ironing. It is excellent in properties and can be processed uniformly without forming pinholes in the coating during molding. In addition, this resin film has excellent adhesion to a metal plate and excellent workability during molding, so that a can with excellent appearance can be obtained.

The resin-coated metal plate according to the present invention exhibits excellent characteristics such as drawability and ironing workability by being formed of the specific two-layer resin layer as described above. The drawn and ironed can according to the present invention is obtained by drawing and ironing such a resin-coated metal plate.

At this time, when a resin-coated metal plate in which a resin coating is provided on only one side of the metal plate is used, it is drawn and ironed so that the resin-coated surface is on the inner side of the can. When manufacturing a drawn ironing can from the above resin-coated metal plate, using a resin-coated metal plate provided with a resin coating on both sides, a drawn ironing can coated not only on the inner surface of the can but also on the outer surface of the can with resin. As a result, it is possible to omit the step of coating the outer surface of the can which is usually performed after the can is made, so that there is no problem at the time of coating such as scattering of the solvent, and the equipment after the can can be significantly reduced.

As a method for producing a drawn ironing can (DI can), various known methods can be employed. As the most general method, it can be manufactured by a method of ironing one or several steps using an ironing punch.

For example, drawing and ironing can be performed under the following conditions. Plank diameter: 100 to 200 mm Aperture condition: 1-stage drawing ratio 1.1 to 2.4 2-stage drawing ratio 1.1 to 1.6 Draw ironing diameter: 3-stage ironing 20 to 100 mmφ Total ironing rate: 20 to 80% The draw-ironing can according to the present invention comprises a metal plate on which a two-layer coating of [A] a crystalline saturated polyester resin layer and [B] an amorphous saturated polyester resin layer, and [A] a crystalline saturated polyester resin layer. It is formed so as to be in contact with the contents of the can, and has extremely low adsorption of terpene-based odors in particular, and has excellent flavor properties (perfume retention properties). Excellent in nature.

[0039]

The resin-coated metal sheet for drawn and ironed cans according to the present invention has excellent adhesion between the resin and the metal sheet, has excellent draw and iron formability, and has excellent resin conformability during molding. And can form a can with excellent appearance.

Further, the drawn and ironed can according to the present invention comprises a punched can,
It has excellent impact resistance that can withstand the impact during the canning process and transportation, and maintains excellent impact resistance even when heated in processes such as drying, printing, and baking after can production.

The drawn and ironed can according to the present invention has no pinholes, is excellent in the long-term storage of the contents, and is also excellent in the preservability such as the scent of the contents and the flavor (flavor retention).

[0042]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

[0043]

Examples 1 to 11 [A] A crystalline saturated polyester resin and [B] an amorphous saturated polyester resin as shown in Table 1 were subjected to Sn plating of 2.8 g / m ² per side on both sides. Steel plate (plate thickness 0.245mm, hardness T-4 equivalent)
On the Sn plating layer on one side of the above, a total of 30 μm in total using a two-type two-layer extrusion T-die so that the amorphous saturated polyester resin layer is in contact with the steel sheet at a film thickness ratio as shown in Table 1 Coated with film thickness. The coated steel sheet was heated, and the steel sheet coated with the resin by the T-die was rapidly cooled to 100 ° C. or less within 10 seconds.

Table 1 shows the intrinsic viscosities [dl / g], Tg (glass transition temperature), and Tm of [A] the crystalline saturated polyester resin and [B] the amorphous saturated polyester resin, respectively.
(Melting point) and Tc (low temperature crystallization temperature).

Tg observed at the time of temperature rise was the temperature at the intersection of the tangent to the peak, and Tc and Tm were the temperatures at the peak of the peak.

Tg, Tm, and Tc are measured at a rate of 10 ° C./min by using a differential thermal analyzer (Perkin Elmer-7 type). Room temperature resin-coated steel sheet obtained in this way,
Drawing and ironing were performed under the following molding conditions so that the resin-coated surface became the inner surface of the can, and a drawn and ironed can was manufactured.

<Molding Conditions> 1. Resin temperature just before drawing and ironing: normal temperature Plank diameter: 137mm 3. Aperture conditions: 1-stage aperture ratio 1.6 2-stage aperture ratio 1.3 4. Ironing punch diameter: 3-stage ironing 65.8mmφ5. Total ironing rate: 67% (i) Evaluation of adhesion of resin coated on inner surface of can The inner surface of the can obtained by squeezing and ironing as described above is washed and canned at 210 ° C. for 10 minutes in an oven. The degree of peeling of the resin at the tip of was observed and evaluated. Table 2 shows the evaluation criteria and Table 3 shows the evaluation results.

(Ii) Evaluation of blister after washing and drying of the can After drawing and ironing, the inner surface of the can is washed, and
After baking at 10 ° C. for 10 minutes, blisters (blisters) formed on the bottom of the can were observed and evaluated. Table 2 shows the evaluation criteria
Table 3 shows the results.

(Iii) Evaluation of flavor adsorption The inner surface of the can obtained as described above was washed,
In an oven for about 2 minutes. Further, the outer surface of the can was painted and baked. 20 in the can thus obtained
Fill with 5% ethanol solution containing ppm limonene,
It was left at 20 ° C. for 10 days. The amount of limonene adsorbed on the film was compared with that of the can (obtained using homo-PET on the innermost surface) obtained in Comparative Example 1 as 100. Table 3 shows the results.

[0050]

Comparative Example 1 A resin-coated metal plate was obtained in the same manner as in Example 1, except that a film (single layer) composed of a crystalline saturated polyester resin as shown in Table 1 was formed to a thickness of 30 μm.

This resin-coated metal plate was made in the same manner as in the example. About the obtained can, the test evaluation was carried out similarly to the Example. Table 3 shows the results.

Table 1 shows the intrinsic viscosity [dl / g], Tg, Tm and Tc of the crystalline saturated polyester resin.

[0053]

Comparative Example 2 A resin-coated metal plate was obtained in the same manner as in Example 1, except that a film (single layer) made of a saturated polyester resin as shown in Table 1 was formed to a thickness of 30 μm.

This resin-coated metal plate was made in the same manner as in the example. About the obtained can, the test evaluation was carried out similarly to the Example. Table 3 shows the results.

Table 1 shows the intrinsic viscosity [dl / g], Tg, Tm and Tc of this saturated polyester resin.

[0056]

Comparative Example 3 A resin-coated metal plate was prepared in the same manner as in Example 1, except that a resin film having a thickness of 30 μm was formed instead of the saturated polyester resin shown in Table 1 for each resin layer. Obtained.

This resin-coated metal plate was made in the same manner as in the example. Table 3 shows the results of test evaluation of the obtained cans in the same manner as in the examples.

[0058]

Comparative Example 4 A saturated polyester resin [A] and a saturated polyester resin [B] as shown in Table 1 were simultaneously biaxially stretched to form a biaxially oriented film having a thickness of 20 μm. A resin-coated metal plate was obtained by laminating on the same metal plate as in Example 1.

This resin-coated metal plate was made in the same manner as in the example. Table 3 shows the results of test evaluation of the obtained cans in the same manner as in the examples.

[0060]

Comparative Example 5 A copolymerized polyester containing 5% by mole of isophthalic acid as a dicarboxylic acid component as shown in Table 1 (IV
= 0.69) by melt extrusion in a conventional manner, and then 3.5
Biaxially stretched by a factor of 3.times.3.7 times, and heat-set at 235.degree. C. to form a biaxially oriented film having a thickness of 16 .mu.m. The [B] layer shown in Table 1 was extruded to a thickness of 14 μm.
A two-layer film was made. A resin-coated metal plate was obtained by bonding such that the layer [B] was in contact with the same steel plate as in Example 1.

The resin-coated metal plate was made in the same manner as in the example. Table 3 shows the results of test evaluation of the obtained cans in the same manner as in the examples.

[0062]

Comparative Examples 6 to 11 Squeezed and ironed cans were obtained in the same manner as in the Example except that the resin layers shown in Table 1 were used. Table 3 shows the results of test evaluation of the obtained cans in the same manner as in the examples.

[0063]

[Table 1]

[0064]

[Table 2]

* 1) The dicarboxylic acid component of the crystalline polyester resin is 100 mol%.

The dicarboxylic acid components other than isophthalic acid include:
Terephthalic acid. * 2) The dihydroxy component of the polyester resin is 100 mol%. The dihydroxy component other than CHDM is ethylene glycol.

* 3) CHDM: cyclohexane dimethanol * 4) Homo PET: crystalline polyester manufactured by Mitsui Pet Resin Co., Ltd. * 5) Biaxially stretched film

[0068]

[Table 3]

[0069]

[Table 4]

Continued on the front page (72) Inventor Takayuki Hiraoka 1-2-1, Waki, Waki-cho, Kuga-gun, Yamaguchi Prefecture Inside Mitsui Petrochemical Industry Co., Ltd. No. 6 1-2 Ki, Mitsui Petrochemical Industry Co., Ltd. (56) References JP-A-5-42643 (JP, A) JP-A-5-338103 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 15/08

Claims (4)

(57) [Claims] 1. A metal plate and a resin film provided on one surface or both surfaces of the metal plate. The resin film is derived from [A] a dicarboxylic acid and a dihydroxy compound, and has a dicarboxylic acid component of 100%. When the molar% is used, the dicarboxylic acid component is derived from a crystalline saturated polyester resin layer composed of 99 to 85 mol% of terephthalic acid and 1 to 15 mol% of isophthalic acid, and [B] a dicarboxylic acid and a dihydroxy compound, The dicarboxylic acid component is composed of terephthalic acid, and the dihydroxy component is two layers of an amorphous saturated polyester resin layer composed of 99 to 70 mol% of ethylene glycol, 1 to 30 mol% of cyclohexanedimethanol and 0 to 5 mol% of diethylene glycol. And [B] such that the amorphous saturated polyester resin layer is in contact with the metal plate. Are layers consisting provided on the metal plate [A] layer and [B] layer with
The resin coating is substantially unoriented and in an amorphous state.
Drawing and ironing a resin-coated metal sheet for cans, characterized in that that. 2. [A] a crystalline saturated polyester resin layer,
[B] The amorphous saturated polyester resin layer has a thickness ratio of [A] layer: [B] layer = 3: 1 to 1: 3, and the drawn and ironed can according to claim 1, wherein For resin coated metal plate. 3. The resin-coated metal plate for a drawn and ironed can according to claim 1, wherein the metal plate is a steel plate or an aluminum plate. 4. The resin-coated metal sheet according to any one of claims 1 to 3 drawing and ironing molding formed by drawn and ironed can.