KR0170070B1 - Preparation process of copolymer polyester film for metal plate heat adhesion laminate - Google Patents

Abstract

In the present invention, 0.001 to 0.5% by weight of spherical silica particles (A) having an average particle diameter of 0.05 to 5.0 µm is added, and 0.01 to 2.0% by weight of inert inorganic particles having an MOS hardness of 6 or more and an average particle diameter of 0.01 to 0.1 µm. The present invention relates to a method for producing a co-polyester film for heat-bonded laminate of metal plate, the co-polyester film prepared in this way has excellent molding processability during the manufacturing process of manufacturing a beverage tube, food tube, etc. by heat-bonded laminate on a metal plate, After molding, it is used for metal plate heat bonding laminates with excellent adhesion, heat resistance, retort resistance, taste and fragrance preservation, low temperature impact resistance and scratch resistance.

Description

Manufacturing method of copolyester film for metal plate heat adhesion laminate

The present invention relates to a method for producing a polyester film for metal plate heat-bonded laminate molding processing, and more particularly, to excellent molding during manufacturing of a beverage tube, food tube, etc. by heat-coating the copolyester film according to the present invention on a metal plate. It relates to a process for producing a co-polyester film for a metal plate heat adhesive laminate having workability, excellent adhesion to the metal plate after molding, heat resistance, retort resistance, taste and fragrance preservation, low temperature impact resistance, scratch resistance.

Conventionally, a method of coating a metal surface by dissolving or dispersing various thermosetting resins such as epoxy or phenol in a solvent to prevent corrosion of inner and outer surfaces of a metal tube is widely used. However, since the method of coating the thermosetting resin requires a long time of 10 minutes to 20 minutes at 180 to 220 ° C. for drying the coated paint, the productivity is relatively low and carbon dioxide generated when using a large amount of organic solvent and drying It is not good because it is accompanied by environmental pollution caused by a large amount of waste water generated during washing.

In order to solve this problem, laminating a thermoplastic resin film such as polyolefin and polyamide on a steel plate, an aluminum plate or a metal plate which has been subjected to various surface treatments such as plating on the surface of each metal plate in recent years, and then making punching, draw, etc. Although a process has been proposed, polyolefin or polyamide does not fully satisfy the molding processability, heat resistance and impact resistance. On the other hand, thermoplastic polyesters, especially polyethylene terephthalate (PET), which are widely used in food containers such as beverages and cooking oils, have excellent moldability, heat resistance, retort resistance, and mechanical strength. Proposed. However, the biaxially oriented polyethylene terephthalate film is excellent in heat resistance, fragrance preservation, etc., but there is a problem that cracks are generated or scratches occur in the film making process, that is, draw process due to insufficient molding processability.

In addition, when laminating an amorphous or low-crystalline aromatic polyester film on a metal plate, the molding processability is excellent, but it is changed to a film that is fragile and damaged by impact on the outside of the tube after printing, heat treatment such as retort treatment, or long-term storage. There is a problem. On the other hand, when the low melting point polyester resin is laminated on the cross section of a PET film to improve adhesiveness, when the draw ratio becomes larger than a certain level by drawing such as draw during the manufacturing process, the strength and crystallinity of each layer may be increased. There is a problem that delamination or cracking occurs due to the decrease in the interfacial adhesion force due to the difference.

The present invention has been made in view of the above problems, and by using a single-layer co-polyester film having a certain degree of polymerization, melting point and crystallinity, proper fluidity is imparted during the tube making process to improve molding processability. In order to improve the cracks and scratches of the film caused by poor frictional characteristics, the inorganic particles that form the surface roughness of the film were changed to improve the frictional resistance, thereby improving the film surface shape characteristics that must be provided during the manufacturing process. . In addition, after molding, the properties of the juice and soft drink containers, which should have adhesion to the metal plate, heat resistance, retort resistance, and impact resistance, were improved.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. For the purposes of the present invention described above, 0.001 to 0.5% by weight of spherical silica particles (A) having an average particle diameter of 0.05 to 5.0 µm are added when preparing a copolyester with an intrinsic viscosity of 0.40 to 0.85 and a melting point of 200 to 235 ° C. After obtaining the copolymer polyester prepared by adding 0.01-2.0 weight% of inert inorganic particle (B) whose average particle diameter is smaller than particle | grains (A) and 0.01-1.0 micrometers and MOS hardness is 6 or more, the conventional biaxially-stretched manufacturing method The obtained film was thermally laminated on a metal plate heated to the melting point or higher of the copolyester to prepare a steel sheet for canning, and thus beverage and food pipes could be manufactured through a conventional canning process. On the other hand, as the metal plate used for thermal fusion, a surface-treated steel plate and an aluminum plate, which were plated with chromium or tin on steel or steel surfaces, were used.

The copolyester used in the present invention is polyethylene terephthalate or polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polycyclohexanedimethylene terephthalate and the like, and copolymerization for achieving the object of the present invention. Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid and maleic acid, among which terephthalic acid, Isophthalic acid, naphthalenedicarboxylic acid, etc. are good at heat resistance, retort resistance, impact resistance, etc.

Among the copolymerization components, diol components include aliphatic glycols such as ethylene glycol, diethylene glycol, butylene glycol, cyclohexane dimethanol, aromatic glycols such as hydroquinone and bisphenol A, and the like. The dicarboxylic acid and diol component enumerated above may be used individually or in combination of 2 or more in the range which does not carry out.

Copolyester used in the present invention is polyethylene terephthalate, polyethylene naphthalate and the like as its main chain and isophthalic acid as the copolymerization component is most suitable for the purpose of the present invention, molding processability, low temperature impact resistance, It is preferable at the point of retort resistance, heat resistance, etc. Moreover, it is good to use three-component glycols, such as diethylene glycol, as a copolymerization component of a diol component in the range which does not impair the characteristic of co-polyester, and is effective for this invention.

The degree of polymerization of the copolyester used in the present invention is intrinsic viscosity of 0.40 to 0.85, preferably 0.65 to 0,80, and more preferably 0.67 to 0.74 after liquid phase polymerization or solid phase polymerization. Preferred in terms of low temperature impact resistance. When the intrinsic viscosity is 0.60 or less, breakage or cracking of the film is likely to occur due to punching or draw during the tube making process, and in particular, low temperature impact resistance is lowered, which is not a preferred method. On the other hand, when the intrinsic viscosity exceeds 0.85, it is not preferable in terms of polymerization process and cost.

The melting point of the copolyester is in the range of 200 to 235 ° C., preferably 215 to 230 ° C., and the melting point is less than 200 ° C., while the workability is improved during the manufacturing process, but the heat resistance and the retort resistance deteriorate. This is not a preferred method. On the other hand, when it exceeds 235 ℃, the heat resistance and retort resistance are improved, but the crystallinity of the polymer is increased, so that the thermal adhesive strength is lowered and the film is peeled off during the manufacturing of the tube after lamination on the metal plate. It is not a preferred method. In addition, since preheating of the metal plate requires a high temperature consumption such as high temperature, the production cost increases.

The copolyester used in the present invention is a polycondensation reaction of terephthalic acid, ethylene glycol and isophthalic acid or a copolymerized component by esterification or exchange of esters to give isophthalic acid copolymerized polyester or copolymerized polyester polymer. Got it. Reaction catalysts used in the transesterification reaction include manganese acetate, magnesium acetate, calcium acetate, potassium acetate, and the like, and were added at the initial or arbitrary stage of the reaction. In the polycondensation reaction step, antimony trioxide or germanium compound was added at the beginning of the polycondensation reaction as a polycondensation catalyst.

On the other hand, if necessary, a lubricant, a fluorescent brightener, an antioxidant, a heat stabilizer, an ultraviolet absorber, an antistatic agent, or the like may be added.

The average particle diameter of the spherical silica particles (A) added in the preparation of the copolyester is 0.05 to 5.0 µm, preferably 0.1 to 1.0 µm, which is suitable for the purpose of the present invention, and the amount is 0.001 to 0.5% by weight, preferably 0.05. -0.2 weight% is favorable. In addition, the particles having an average particle diameter of 0.01 to 1.0 µm, preferably 0.05 to 0.5 µm, as the two-component particles and having a MOS hardness of 6 or more are inert inorganic materials such as titanium dioxide, alumina oxide and zirconia. The particle | grains were added in the range of 0.01-2.0 weight%, Preferably 0.1-1.0 weight% was achieved the objective of this invention.

The present invention will be described in more detail, the average particle size ratio (R) of the particles to be used satisfies the range of 1 to 10 and the added weight ratio (W) of the particles at the same time satisfying the range of 0.01 to 1.0 range of the average particle size ( If the value of R) is 1 or less, the film surface may be damaged by cracks, scratches, etc. by dies in the drawing process at the time of manufacturing. When the average particle size ratio (R) is 10 or more, the dispersibility of particles may be poor. Coarse protrusion occurs, and scratching by dies occurs during manufacturing. Where the average particle size ratio (R) And the added weight ratio (W) of the particles Indicates.

In addition, when the particle addition ratio (W) is 0.01 or less, the amount of particles added as the bottom reinforcing agent is low, so that the friction resistance at the time of steel making is poor, and when the particle addition ratio (W) is 1.0 or more, the surface of the film is poor when heat-bonded to the metal plate. As a result, the adhesive strength is weakened and damage to the surface of the film caused by the die during the pipe manufacturing cannot satisfy the object of the present invention.

The copolymerized polyester film used in the present invention may be prepared by melting the copolymerized polyester at a temperature higher than the melting point in an extruder, followed by extrusion, cooling, and solidifying through a die, followed by longitudinal stretching, transverse stretching, and heat setting. there was. 12-40 micrometers is preferable for the final aftercoat of the produced film, More preferably, 15-30 micrometers is advantageous for the objective of this invention. When the thickness of the film is 12 μm or less, breakage of the film is likely to occur during the steelmaking process. On the contrary, when the film thickness exceeds 40 μm, the film has excessive quality characteristics, which is uneconomic. In the present invention, as the metal plate for laminating the copolyester film, in particular, the metal plate for steel making, tin plated steel plate, chromium plated steel plate, chromium trioxide plated steel plate, aluminum plate and the like are suitable. The method of laminating a film to a metal plate is as follows.

First, the lubricant on the metal plate is washed and then heated to the melting point or higher of the film to be laminated, and then laminated using one or more of the metal plates using a compression ratio as necessary. After the lamination, in order to prevent crystallization of the film, it was rapidly cooled by using a cooling apparatus cooled to below the glass transition temperature of the film, thereby obtaining a metal plate for forming a steel sheet in which a co-polyester film was thermally laminated.

Hereinafter, Examples of the present invention will be described, and the properties of each copolyester and film were measured by the following method.

Unique viscosity

2.0 g of each copolyester was dissolved in a 1,1,2,2-tetrachloroethane / phenol (60/40 wt%) mixed solvent and measured at 25 ° C.

Glass transition temperature and melting point

A 6.0 mg sample of copolyester was obtained using a DuPont 9100 differential scanning calorimetry at a temperature increase rate of 20 ° C./min, and the melting point was taken as the peak temperature.

Acetaldehyde concentration

Each copolyester was pulverized using a freeze crusher, and then 2.0 g of the pulverized product was placed in a pressure-resistant container together with secondary distilled water, treated at 120 ° C. for 60 minutes, and quantified using high sensitivity gas chromatography.

Adhesion

Using a cupping tester, a laminate metal plate manufactured by pressing the co-polyester film according to the present invention to a metal plate heated at 200 to 240 ° C. at a pressure of 20 kg / cm 2 and then cooling it using cooling water cooled to a glass transition temperature or lower. 10 cups each, each cup was cupped to a depth of 8 mm, then peeled off with an adhesive tape, and the adhesive force was evaluated by the number of peeled samples.

(Circle): It has not peeled, (triangle | delta): It peels 3-5 pieces, and X: It peels six or more.

Friction resistance evaluation

The laminated metal plate was cut into a circular shape having a diameter of 150 mm, a monolithic tube having a diameter of 60 mm was made through a punching and a drawing process, and the scratch resistance and the peeling degree of the film surface were observed to evaluate the friction resistance.

○: No scratch or peeling phenomenon on the film surface

△: partial scratches and peeling

×: large amount of scratches or complete peeling

Low temperature impact resistance

After filling the tube made as described above with water and cooling to 10 ℃ 10 drops for each composition at 30 cm height, filled with 1% saline solution and left for 24 hours at 80 ℃ after generation on the inner surface It was evaluated by observing the rust development state.

○: no rust occurrence, △: less than 3 rust less than 1mm,

×: rust generation

Moldability

The metal sheet laminated with the copolyester film was evaluated for the degree of cracking or breaking of the film caused by poor drawability in the stretching step during the steelmaking and the uniformity of the cut surface in the punching step to evaluate the molding processability.

(Circle): The film is not cracked or broken and the cutting surface is uniform.

(Triangle | delta): The crack of some films generate | occur | produces and a cut surface peels partially.

×: breakage and cracking of the film occurs in a large amount of portions and the cutting surface is uneven

Example 1

5.34 kg of dimethyl terephthalate, 0.73 kg of dimethyl isophthalate and 3 liters of ethylene glycol were added to the reaction tube, and after the temperature of the reaction tube reached 145 ° C, 0.03 weight% of manganese acetate and 0.007 weight of potassium acetate based on 100 parts by weight of the resulting polymer. %, Tetramethylammonium hydroxide 0.01% by weight, 0.1% by weight of the spherical silica particles having an average particle diameter of 0.3㎛, 0.3% by weight of alumina oxide particles having an average particle diameter of 0.05㎛ mixed and added to the reaction temperature of 235 ℃ The transesterification reaction is carried out until it is reached.

When the temperature of the reaction reaches 235 ° C, 0.03% by weight of antimony trioxide and 0.03% by weight of trimethylphosphate are added, and then the temperature of the reaction is raised to 245 ° C to remove excess ethylene glycol in the reaction, and then slowly reacted for 45 minutes. Reduce the pressure to 0.5torr. At the same time as the pressure reduction, the temperature of the reaction tube is raised, the temperature of the reactant is raised to 285 ° C, and then the polycondensation reaction is performed.

The copolymer polyester having the intrinsic viscosity of 0.67 and the melting point of 222 ° C. was dried at 80 ° C./60 min, 120 ° C./280 min under reduced pressure, melt-extruded at a melting temperature of 275 ° C., and then cooled and solidified to obtain an unstretched film. Prepared. The unstretched film was stretched 3.1 times in the longitudinal direction at 3.2 ° C. and 3.2 times in the transverse direction at 105 ° C., and then heat-set at 190 ° C. to produce a biaxially stretched film having a final thickness of 25 μm. The biaxially oriented film prepared was chrome oxide plated metal plate preheated to 230 ° C., and then pressed on both sides using a squeeze roll, and then quenched in 50 ° C. cooling water to prepare a metal plate on which a copolyester film was laminated. The round tube was formed through a process such as punching and draw.

As shown in the following Table 1 and Table 2 showed excellent friction resistance and adhesion to the metal plate after molding, heat resistance, retort resistance, low temperature impact resistance, taste and fragrance preservation.

Example 2

In the same manner as in Example 1, 0.08% by weight of spherical silica particles having an average particle diameter of 0.5 μm and 0.2% by weight of alumina oxide particles having an average particle diameter of 0.1 μm were mixed to prepare a copolyester, which is then obtained by using the same. A biaxially oriented film was prepared and laminated on a metal plate plated with chromium and chromium oxide to compare properties. The results are shown in Tables 1 and 2 below.

Example 3

In the same manner as in Example 1, 0.15% by weight of spherical silica particles having an average particle diameter of 0.2 µm and 0.3% by weight of alumina oxide particles having an average particle diameter of 0.05 µm were mixed to prepare a copolyester, and then, the resultant was 25 A biaxially oriented film was prepared and laminated on a metal plate plated with chromium and chromium oxide to compare properties. The results are shown in Tables 1 and 2 below.

Example 4

In the same manner as in Example 1, 0.1 wt% of spherical silica particles having an average particle diameter of 0.3 μm and 0.25 wt% of titanium dioxide particles having an average particle diameter of 0.1 μm were mixed to prepare a copolyester, and then, the copolyester was used. A biaxially oriented film was prepared and laminated on a metal plate plated with chromium and chromium oxide to compare properties. The results are shown in Tables 1 and 2 below.

Comparative Example 1

Copolymerized polyethylene terephthalate obtained by adding 0.1% by weight of plate-shaped kaolin particles having an average particle diameter of 0.2 μm and 0.25% by weight of alumina oxide particles having an average particle diameter of 0.8 μm was mixed in the same reaction tube as in Example 1 and polycondensed in the same manner. After the treatment in the usual manner, a film having a thickness of 25 µm was obtained.

The prepared films were laminated on a chromium oxide plated metal plate preheated to 230 ° C. using a compression roll, and then the properties were compared. The results are shown in Tables 1 and 2 below.

Comparative Example 2

Copolymerized polyester obtained by adding 0.15% by weight of spherical silica particles having an average particle diameter of 0.3 μm and 0.3% by weight of calcium carbonate particles having an average particle diameter of 0.6 μm was added to a reaction tube, followed by polycondensation in the same manner as in Example 1. After using, the film of 25 micrometers was obtained.

The prepared films were laminated on a chromium oxide plated metal plate preheated to 230 ° C. using a compression roll, and then the properties were compared. The results are shown in Tables 1 and 2 below.

Comparative Example 3

0.05 wt% of spherical silica particles having an average particle diameter of 1.2 mu m and 0.15 wt% of alumina oxide particles having an average particle diameter of 0.05 mu m were added to the reaction tube, followed by polycondensation in the same manner as in Example 1 After using, the film of 25 micrometers was obtained.

The prepared film was laminated on a chromium oxide plated metal plate preheated to 230 ° C., and then its properties were compared. The results are shown in Tables 1 and 2 below.

Comparative Example 4

0.3 wt% of the spherical silica particles having an average particle diameter of 0.2 mu m and 0.2 wt% of the alumina oxide particles having an average particle diameter of 0.5 mu m were added to the reaction tube, followed by polycondensation in the same manner as in Example 1 After using, the film of 25 micrometers was obtained.

The prepared film was laminated on a chromium oxide plated metal plate preheated to 230 ° C., and then its properties were compared. The results are shown in Tables 1 and 2 below.

Claims (5)

Manufactured by co-condensation of dicarboxylic acid component composed of saturated fatty acid, dicarboxylic acid or derivatives thereof and three-component glycol mainly composed of ethylene glycol with copolyester having an intrinsic viscosity of 0.4 to 0.85 and melting point of 200 to 235 ° C. The manufacturing method of the co-polyester film for metal plate heat adhesion lamination characterized by the above-mentioned. The method according to claim 1, wherein 0.001 to 0.5% by weight of spherical silica particles (A) having an average particle diameter of 0.05 to 5.0 µm is added, and 0.01 to 2.0 inert inorganic particles having a MOS hardness of 6 or more and an average particle diameter of 0.01 to 0.1 µm. A method for producing a co-polyester film for metal plate thermal bonding laminate, characterized in that the addition by weight. The method of claim 2, wherein the inert inorganic particles are titanium dioxide, alumina oxide, or zirconia. The method of claim 2, wherein the average particle diameter (R) of the particles And the added weight ratio (W) of the particles The average particle diameter ratio (R) of a particle | grain is the range of 1-10, and the addition weight ratio (W) of particle | grains is a range of 0.01-1.0, The manufacturing method of the copolyester polyester film for metal plate heat bonding laminates of Claim 1 characterized by the above-mentioned. The thickness of the polyester film produced by copolymerization is 12-40 micrometers, The manufacturing method of the copolyester polyester film for metal plate heat-sealing laminate of any one of Claims 1-4 characterized by the above-mentioned.