JP3617735B2 - Polyester film for laminating metal plates - Google Patents

Description

【００３１】
【表２】

【００３２】
上記実施例および比較例で得られた計１１種類のフィルムを２６５℃に加熱した板厚０.２５ｍｍのニッケルめっき鋼板の片面に貼合せ、水冷した後６０ｍｍ径の円板状に切り取り、絞りダイスとポンチを用いて６段階で深絞り加工し、１４ｍｍ径の乾電池正極缶を作成した。
【００３３】
この正極缶について以下の観察および試験を行い、各々下記の基準で評価した。
（１）深絞り加工性
◎：乾電池正極缶が異常なく成形加工され、缶内面のフィルムに剥離、クラックや破断が全く認められない。
○：缶内面のフィルムに剥離、クラック、破断等の大きな欠陥は認められない。
×：缶内面のフィルムの一部にフィルム剥離、クラック、破断等の大きな欠陥が認められる。
この評価の結果を表３に示す。
【００３４】
次に、実施例１〜７、および比較例１〜４で作成したフィルムを使用した正極缶を真空中（０.２torr）において、５００℃で１０分間保持した。
以上の作成した１１種の正極缶を使用しアルカリマンガン電池を作成し以下の試験を行い、下記の基準で評価した。
【００３５】
（２）乾電池内部抵抗
作成したアルカリマンガン乾電池の内部抵抗を測定し下記の基準で評価した。
◎：１５０ｍΩ未満
○：１５０ｍΩ以上、２００ｍΩ未満
×：２００ｍΩ以上
この評価の結果を表３に示す。
【００３６】
表３の結果から実施例のフィルムは、深絞り加工性、導電性、電池内部抵抗の低減に対して優れていることがわかる。
【００３７】
【表３】

【００３８】
【発明の効果】
本発明の金属板貼合せ加工用ポリエステルフィルムは、金属板と貼合せた後、深絞り加工して、例えば乾電池の正極缶等に深絞り成形するに当り、深絞り加工性、導電性、電池内部抵抗の低減に優れたものであり、例えば乾電池正極缶として極めて有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polyester film for laminating a metal plate. More specifically, it exhibits excellent molding processability when forming such as drawing so that it becomes the inner surface after being bonded to a metal plate, and is useful for, for example, reducing the contact resistance with the positive electrode mixture of a dry battery. The present invention relates to a polyester film for metal plate laminating processing that exhibits excellent electrical conductivity.
[0002]
[Prior art]
Carbon is coated on the inner surface of a positive electrode can (hereinafter referred to as a can) of an alkaline manganese dry battery in order to reduce the contact resistance with the positive electrode mixture. Such a positive electrode can is manufactured by applying carbon to a metal plate to form a conductive film, and then performing molding processing so that the coated surface becomes the inner surface side.
[0003]
[Problems to be solved by the invention]
Therefore, there is a problem that the inside of the process is contaminated by the scattering and scraping of the carbon particles in the carbon coating process on the metal plate and the positive electrode can molding process.
Furthermore, since an organic solvent is used for carbon coating, development of a method that does not use these is required for the purpose of improving hygiene and preventing pollution.
[0004]
[Means for Solving the Problems]
As a result of intensive research to solve the above-mentioned problems, the inventors of the present invention have achieved extremely high contact resistance with a positive electrode mixture of a dry battery, for example, by attaching a conductive film in which carbon is added to a polyester film to a metal plate. The present inventors have found that it can be made small and have completed the present invention.
[0005]
That is, according to the present invention, first, (a) a polyester having an intrinsic viscosity of 0.45 to 0.8 dl / g and a melting point of 205 to 260 ° C. (hereinafter referred to as a first polyester) and (b ) Carbon black and / or artificial graphite dispersed and contained in the first polyester, the content of which is 2 to 30 weight based on the total weight of the first polyester and carbon black and / or artificial graphite % and is, contain-than and X-ray diffraction intensity ratio is represented by the following formula (1)
0. 15 ≦ f (1-10) / f (100) (1)
Here, f (1-10) is the X-ray diffraction intensity by the (1-10) plane parallel to the film surface, and f (100) is the X-ray diffraction intensity by the (100) plane parallel to the film surface. ,
The polyester film for metal plate bonding processing characterized by satisfying the above is provided.
[0006]
The first polyester in the present invention is a polyester having dibasic acid and glycol as main components. Examples of the dibasic acid include aromatic dibasic acids such as terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid; aliphatic dibasic acids such as adipic acid, azelaic acid, sebacic acid and decanedicarboxylic acid; cyclohexanedicarboxylic acid Examples thereof include alicyclic dibasic acids such as acids. Examples of the glycol component include ethylene glycol, propylene glycol, butylene glycol, and cyclohexanedimethanol. Of course, it may be a copolymer comprising a plurality of dibasic acids and / or a plurality of glycols. Moreover, the blend type | system | group of 2 or more types of polyester may be sufficient.
[0007]
The first polyester in the present invention is preferably a homopolymer or copolymer using aromatic dicarboxylic acid as the main dicarboxylic acid component and ethylene glycol as the main glycol component among the above polyesters. Among these polyesters, a polyethylene terephthalate homopolymer or copolymer is particularly preferable.
[0008]
Moreover, melting | fusing point of the 1st polyester in this invention is 205-260 degreeC , Preferably it is 215-250 degreeC. If the melting point of the first polyester is lower than 205 ° C. and less than 180 ° C., the film is fused due to heat generated during deep drawing, making it difficult to mold. On the other hand, if the melting point exceeds 270 ° C., which is higher than 260 ° C. , the crystallinity of the polymer is too high and the moldability is impaired.
Here, the melting point of the polyester is measured by a method of obtaining a melting peak using Du Pont Instruments 910 DSC at a heating rate of 20 ° C./min. The sample amount is 20 mg.
[0009]
The 1st polyester in this invention is not limited by the manufacturing method. Among them, for example, a method in which terephthalic acid, ethylene glycol and a copolymer component are esterified and then a reaction product obtained is polycondensed to obtain a copolymer polyester, or dimethyl terephthalate, ethylene glycol and a copolymer component are transesterified. A method in which the reaction product obtained by the reaction is subjected to a polycondensation reaction to obtain a copolyester is preferably used. In the production of polyester, other additives such as an antioxidant, a heat stabilizer, an antistatic agent and the like can be added as necessary.
[0010]
The intrinsic viscosity of the first polyester in the present invention is 0.45 to 0.8 dl / g, preferably 0.48 to 0.75 dl / g, and more preferably 0.50 to 0.7 dl / g. When the intrinsic viscosity is less than 0.45 dl / g, film breakage during film stretching increases, and breakage tends to occur when deep drawing is performed after the obtained film is bonded to a metal plate. On the other hand, if the intrinsic viscosity exceeds 0.8 dl / g, the quality is excessive and the productivity of the raw material polymer is lowered, which is uneconomical.
Here, the intrinsic viscosity of the first polyester in the film was obtained by dissolving the film in o-chlorophenol, removing carbon particles by a stretching separator and filtration, and measuring at a temperature of 35 ° C.
[0011]
The addition concentration of carbon black and / or artificial graphite in the present invention is 2 to 30% by weight, preferably 3 to 25% by weight, more preferably 5 to 20% by weight, based on the total weight with the first polyester. It is. If it is less than 2% by weight, for example, conductivity sufficient to reduce the contact resistance between the dry cell positive electrode can and the positive electrode mixture cannot be obtained. On the other hand, when it exceeds 30% by weight, it becomes difficult to add and disperse the polyester.
[0012]
The average particle diameter of primary particles of carbon black or artificial graphite added to the first polyester in the present invention is preferably 0.01 to 0.2 μm. The average particle size is more preferably 0.01 to 0.15 μm, and still more preferably 0.015 to 0.100 μm. If the average particle size of the primary particles is less than 0.01 μm, the specific surface area tends to increase, so it tends to be difficult to add to a high concentration. If the average particle size exceeds 0.2 μm, higher-order aggregated particles in the polyester film Since the diameter tends to increase, the film tends to break during stretching, and the productivity tends to decrease.
[0013]
The average particle size of the aggregated particles of carbon black and artificial graphite contained in the polyester film is preferably 10 μm or less, more preferably 5 μm or less. When the particle diameter of the aggregated particles exceeds 10 μm, breakage during film stretching tends to occur and productivity is lowered.
[0014]
Various methods can be used to incorporate polyester into carbon black or artificial graphite. The following method can be mentioned as the typical method.
(A) A method of adding before transesterification or esterification reaction at the time of polyester synthesis or adding before the start of polycondensation reaction.
(A) A method of adding to polyester and melt-kneading.
(C) In the above methods (a) and (b), a master pellet to which a large amount of carbon black or artificial graphite is added is produced, kneaded with carbon black or polyester not containing artificial graphite, and a predetermined amount of carbon black or A method for adjusting artificial graphite to be contained.
[0015]
The thickness of the polyester film of the present invention is preferably 5 to 100 μm, more preferably 8 to 75 μm, and particularly preferably 10 to 50 μm. If the thickness is less than 5 μm, cracks and the like are likely to occur during processing, while those exceeding 100 μm are not economical compared to the carbon coating method, and the amount of filler such as a positive electrode mixture that can be filled in the battery is small. It is not preferable.
[0016]
Polyester film of the present invention, X-rays diffraction intensity ratio of the full Irumu satisfies the following formula (1). When this X-ray diffraction intensity ratio is less than 0.15, the orientation of the film becomes too high, and cracks and breaks are likely to occur during molding.
0.15 ≦ f (1-10) / f (100) (1)
Here, the X-ray diffraction intensity ratio is measured using CuK-α as an X-ray source, divergence slit 1/2 °, scattering slit 1/2 °, light receiving slit 0.15 mm, scan speed 1.000 ° / X-ray diffraction intensity by the (100) plane parallel to the film surface: f (100), parallel to the film surface (1-10) by the multiple peel separation method using the Pseudo Voight peel model. The ratio f (1-10) / f (100) of the diffraction intensity by the surface: f (1-10) is measured. However, X-ray diffraction intensity determined the area of the diffraction peak of each crystal plane, and this area was defined as X-ray diffraction intensity.
[0017]
The polyester film in the present invention is a method in which the polyester is melted and extruded from a die and immediately quenched to obtain a substantially amorphous unstretched polyester film, or the polyester is melted and extruded from a die and immediately quenched and substantially cooled. In particular, an amorphous unstretched polyester film can be produced by a method of biaxially stretching and heat setting to obtain a biaxially stretched polyester film.
[0018]
According to the present invention, by using the polyester film of the present invention as a laminated film, it is possible to further improve the film formability and deep drawability during biaxial stretching. Such a laminated film has the following configuration.
[0019]
That is, according to the present invention, secondly, the first polyester film of the present invention containing 10 to 30% by weight of carbon black and / or artificial graphite, and (a ′) the intrinsic viscosity is 0.52 dl / a polyester having a melting point of 180 to 270 ° C. and carbon black and / or artificial graphite dispersed and contained in the polyester (a ′), the content of which is polyester (a ′ And a second polyester film containing 10% by weight or less based on the total weight of carbon black and / or artificial graphite (b ′) A polyester film for laminating is also provided.
[0020]
In the laminated polyester film, the first polyester film has a carbon black and / or artificial graphite content of 10 to 30% by weight. Regarding the first polyester film, it should be understood that the other matters not described here are applied as they are for the polyester film of the present invention.
[0021]
In the second polyester film, the polyester film has an intrinsic viscosity of 0.52 dl / g or more, preferably 0.54 to 0.8 dl / g. Carbon black and / or artificial graphite is 10% by weight or less, preferably 2 to 6% by weight, based on the total weight with the polyester. Regarding the second polyester film, it should be understood that the other matters not described here are applied as they are to the description of the polyester film of the present invention.
[0022]
In the laminated film, the thickness (Xb) of the second polyester film (B layer) is 0.05 (Xb / Xa) with the thickness (Xa) of the first polyester film (A layer). About -1.0 is desirable, and further 0.1-0.7 is desirable.
[0023]
The laminated film is prepared by melting the polyester constituting the A layer and the B layer separately, co-extruding from a die, laminating and fusing before solidification, and immediately quenching to form a substantially amorphous laminated unstretched polyester film and Or a method of forming a biaxially stretched laminated polyester film by biaxially stretching and heat-setting the laminated unstretched polyester film.
[0024]
The metal plate to which the polyester film (including laminated film) of the present invention is bonded, particularly as a metal plate for can manufacturing, is a nickel-plated steel plate, galvanized steel plate, chrome-plated steel plate, copper-plated steel plate, tin-plated steel plate, nickel-tin. Plates of plated steel, tin-free steel, aluminum, etc. are appropriate. The polyester film is bonded to the metal plate by, for example, heating the metal plate above the melting point of the film, bonding the film and then cooling, and the surface layer portion (thin layer portion) of the film in contact with the metal plate is amorphous. It can carry out by the method of making and adhering.
Moreover, since the film after dry battery positive electrode can shaping | molding reduces contact resistance with a positive mix, it can heat-process to 350 degreeC or more.
[0025]
【Example】
Hereinafter, the present invention will be further described with reference to examples.
Examples 1 to 3 and Comparative Examples 1 and 2
After melting the polyester shown in the table to which carbon black or artificial graphite having the concentration shown in Table 1 was added, it was extruded from a die and rapidly solidified to prepare an unstretched film.
Next, the unstretched film was longitudinally stretched 3.0 times at 110 ° C., then stretched 3.0 times at 120 ° C., and heat-set at 180 ° C. to prepare a biaxially oriented film having a thickness of 4 to 25 μm. . The properties of this film are shown in Table 1.
[0026]
Example 4
Two types of polyester added with carbon black or artificial graphite having the concentrations shown in Table 2 were melted separately, then co-extruded from a die, laminated and fused before solidification, and then rapidly solidified to create a laminated unstretched film. .
Next, the unstretched film was longitudinally stretched 3.0 times at 110 ° C., then stretched 3.0 times at 120 ° C., and heat-set at 180 ° C. to prepare a biaxially oriented film having a thickness of 25 μm. The properties of this film are shown in Table 2.
[0028]
Examples 5 and 6 and Comparative Examples 3 and 4
After melting the polyester shown in Table 1 to which carbon black or artificial graphite having the concentration shown in Table 1 was added, it was extruded from a die and rapidly cooled and solidified to prepare an unstretched film having a thickness of 15 to 25 μm. The properties of this film are shown in Table 1.
[0029]
Example 7
After melting the polyester to which the carbon black or artificial graphite having the concentration shown in Table 1 was added, it was extruded from a die and then rapidly cooled and solidified to prepare an unstretched film. Next, an attempt was made to biaxially stretch the unstretched film. However, since it was difficult to form a film due to film breakage, a 25 μm unstretched polyester film was evaluated. The properties of this film are shown in Table 1.
[0030]
[Table 1]

[0031]
[Table 2]

[0032]
A total of 11 types of films obtained in the above examples and comparative examples were bonded to one side of a 0.25 mm thick nickel-plated steel sheet heated to 265 ° C., water-cooled, then cut into a disk shape with a diameter of 60 mm, and a drawing die And a deep punching process in 6 stages using a punch and a 14 mm diameter dry cell positive electrode can.
[0033]
The positive electrode can was observed and tested as follows, and evaluated according to the following criteria.
(1) Deep-drawing workability: A dry cell positive electrode can is molded without abnormality, and no peeling, cracking or breakage is observed on the film on the inner surface of the can.
○: No major defects such as peeling, cracking or breaking are observed in the film on the inner surface of the can.
X: A big defect, such as film peeling, a crack, and a fracture | rupture, is recognized in a part of film of a can inner surface.
The results of this evaluation are shown in Table 3.
[0034]
Next, in a vacuum (0.2 torr) and cathode can using the film prepared in Example 1-7, and Comparative Examples 1 to 4 were held at 500 ° C. 10 min.
Using the 11 types of positive electrode cans prepared above, an alkaline manganese battery was prepared and subjected to the following tests, and evaluated according to the following criteria.
[0035]
(2) Internal resistance of dry cell The internal resistance of the prepared alkaline manganese battery was measured and evaluated according to the following criteria.
A: Less than 150 mΩ ○: 150 mΩ or more, less than 200 mΩ ×: 200 mΩ or more The results of this evaluation are shown in Table 3.
[0036]
From the results in Table 3, it can be seen that the films of the examples are excellent in deep drawing processability, conductivity, and reduction in battery internal resistance.
[0037]
[Table 3]

[0038]
【The invention's effect】
The polyester film for laminating a metal plate of the present invention is bonded to a metal plate, and then deep-drawn, for example, when deep-drawing into a positive electrode can of a dry battery, deep drawing workability, conductivity, battery It is excellent in reducing internal resistance and is extremely useful, for example, as a dry battery positive electrode can.

Claims (5)

(A) a polyester having an intrinsic viscosity of 0.45 to 0.8 dl / g and a melting point of 205 to 260 ° C., and (b) carbon black and / or artificial graphite dispersed and contained in the polyester, Its content is 2 to 30% by weight based on the total weight of polyester and carbon black and / or artificial graphite.
Contain-than and X-ray diffraction intensity ratio is represented by the following formula (1)
0. 15 ≦ f (1-10) / f (100) (1)
Here, f (1-10) is the X-ray diffraction intensity by the (1-10) plane parallel to the film plane, and f (100) is the X-ray diffraction intensity by the (100) plane parallel to the film plane. ,
A polyester film for metal plate laminating processing, characterized by satisfying The film according to claim 1, wherein the average particle size of primary particles of carbon black and artificial graphite is 0.01 to 0.2 µm, and the average particle size of aggregated particles is less than 10 µm. The film according to claim 1, wherein the film is laminated on a metal plate, formed into a dry cell positive electrode can by deep drawing, and then heated to 350 ° C or higher. The first polyester film according to any one of claims 1 to 3 , which contains carbon black and / or artificial graphite in an amount of 10 to 30% by weight; and (a '). The intrinsic viscosity is 0.52 dl / g or more. Polyester having a melting point of 180 to 270 ° C. and (b ′) carbon black and / or artificial graphite dispersed and contained in the polyester (a ′), the content of which is polyester (a ′) and carbon black And / or 10 wt% or less based on the total weight of artificial graphite (b '),
A polyester film for laminating a metal plate, comprising a laminated film with a second polyester film containing The film according to claim 4 , which is used by being bonded to a metal plate, formed into a dry cell positive electrode can by deep drawing, and then heated to 350 ° C or higher.