JP2005088600A - Manufacturing process for resin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing process for a resin film with good design characteristics, which is excellent in mechanical properties and does not undergo whitening despite its high crystallinity as an independent film or a metal sheet laminated film, when treated with a heat near or above its fusing point. <P>SOLUTION: The manufacturing process for the resin film is characterized as follows. Two different resin materials A and B selected from polypropylene, polyethylene, polystyrene, polymethyl pentene, cycloolefin resin, acrylic resin, polycarbonate, polyphenylene sulfide, vinyl resin, polylactic resin and nylon resin are melted separately. They are delivered in the molten state into one of mixing devices selected from a single screw extruder, a twin screw extruder, a dynamic mixer and a static mixer; mixed, extruded and made into the film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention mixes and extrudes two different types of resin raw materials, and is suitable for various food packaging, general industrial use, optical use, electrical material use, molding process use, etc. The present invention relates to a method for producing a useful film.

  Metal cans, which are one form of food and beverage packaging containers, are excellent in mechanical strength, so the contents can be stored for a long period of time. Since it can be easily sterilized, it is highly reliable for safety and hygiene as a packaging container. In addition, the contents can be stored in a warmed state, and cans can be separated and recovered after use. In recent years, various contents are filled and used in large quantities.

  The inner and outer surfaces of metal cans for food and drink have thermosetting resins as the main component for the purpose of maintaining the flavor of the contents and preventing corrosion of the metal cans, or improving the cosmetics of the outer surface of the cans and protecting the printed surface. Coatings that apply have been used on metal cans. However, since such metal cans use a large amount of solvent at the time of manufacture, the effects on the environment due to solvent removal during manufacture, sanitary problems due to residual solvent in the coating film, and poor reaction during heat curing. There are problems such as a decrease in flavor due to the remaining oligomer.

  In order to overcome these problems, a method of laminating a plastic film to metal has been proposed. As a metal plate obtained by laminating a polyester resin film on a metal plate, a so-called three-piece can (hereinafter abbreviated as 3P can) and a two-piece can (hereinafter abbreviated as 2P can) have been proposed. In view of making cans seamless, the spread of 2P cans is desired.

  As a general method for producing a 2P can, a method of punching a metal plate laminated with a plastic film with a can making machine and making it a seamless can by a drawing and ironing process is common. In this can making process, the film is required to follow the extension of the metal plate while being subjected to squeezing and ironing shear.

  For these required properties, a film excellent in canability when blended with a polyethylene terephthalate (PET) polyester resin having a specific intrinsic viscosity and a polybutylene terephthalate (PBT) polyester resin having a specific intrinsic viscosity Has been proposed (see, for example, Patent Documents 1, 2, and 3).

  In making a film made of two kinds of polyester, the film follows in the deformation of the metal at the time of can molding and the flavor property of the can contents are compatible. For that purpose, it is necessary to have appropriate crystallinity. For that purpose, it is necessary to prevent copolymerization of different polyesters by transesterification. For this reason, for example, a device is devised to reduce the amount of heat applied to the film in the melting time of the resin, the subsequent stretching, and the heat treatment process. However, in both cases where the film is applied to a metal or when the film is processed as it is, if the film is processed at or near the melting point of the film, the film is whitened with cooling, which is inferior in design. There wasn't. Moreover, it was a problem that the film on a metal plate was easily damaged by the viscosity fall of a film.

The cause is expected as follows. In order to mix resins having different melting points such as PET and PBT, it is necessary to melt them at a temperature higher than the melting point of PET having a high melting point (about 255 ° C.). Therefore, for PBT having a low melting point (about 225 ° C.), the temperature becomes higher than the optimum extrusion temperature, so that the quality deteriorates due to the deterioration of the resin and the reduction of the viscosity. In addition, the crystallization speed of PET and PBT seems to change in the mixed state of both, but it seems to cause whitening because the crystallization speed decreases even if the mixing is insufficient or sufficient.
Japanese Patent No. 2882985 Japanese Patent No. 3020731 JP-A-10-195210 Japanese Patent Laid-Open No. 10-110046

  In the present invention, it relates to a method of preparing a film by mixing and extruding two kinds of resin raw materials having different structures, and preferably has excellent mechanical properties and high crystallinity, and the film alone or a metal plate It is related with the manufacturing method of the resin film which is excellent in the design property which is not whitened even if it heat-processes to the melting | fusing point vicinity or more than melting | fusing point of a film, Preferably it is for metal lamination and the manufacturing method of the resin film for shaping | molding processes.

  The present invention is a method of mixing and extruding two kinds of resin raw materials having different configurations, and making a film by feeding raw material A and raw material B into separate extruders, respectively, and after melting, It is related with the manufacturing method of the resin film obtained by supplying to a mixing apparatus, mixing, and extruding.

According to the method for producing a resin film of the present invention, it has excellent mechanical properties, has a high crystallinity, is bonded to a film alone or a metal plate, and is whitened even when heat-treated near or above the melting point of the film. The resin film which is excellent in the design property which does not do can be manufactured.
The resin film production method of the present invention is for general packaging, antistatic properties, gas barrier properties, metal laminating, heat sealing, anti-fogging, metal deposition, easy tearing, easy opening, bag making packaging, retort packaging For boil packaging, medicine packaging, easy adhesion, magnetic recording, capacitor, ink ribbon, transfer, adhesive label, stamping foil, gold and silver thread, tracing material, mold release, shrink film It became the most suitable manufacturing method that can be used for various purposes.

  The resin used in the present invention is not limited, and examples thereof include polypropylene, polyethylene, polystyrene, polymethylpentene, cyclic olefin resin, acrylic resin, polycarbonate, polyphenylene sulfide, vinyl resin, and polylactic acid. Nylon resin.

  In the present invention, the film production method used is a method of mixing and extruding two types of resin raw materials having different configurations, and producing a film by putting the raw material A and the raw material B into separate extruders, and after melting, It is characterized in that it is obtained by supplying it to one mixing device in the molten state, mixing and extruding. When a film is produced using two types of different resins, it is necessary to control the mixed state of the two.

  In the production of a normal polyester film, materials constituting a single layer are put into a single extruder, melted and extruded to form a film. The patents exemplified in the prior art section also use two or more different materials, but the extruder uses a single extruder. This is presumed to be the result of considering the stability and economical efficiency during film formation according to the conventional technique. Therefore, it seems that higher quality films were difficult. However, it was found that by adopting the method described later, a film with improved quality can be obtained while maintaining the stability of film formation.

  The reason why this method is good for quality and productivity is presumed as follows. For example, when making a blend film of PET (melting point 255 ° C) and PBT (melting point 220 ° C) using only a single extruder with a single or twin screw, which is a commonly used method, both Since the difference in melting point is 30 ° C. or more, when both are blended from the resin chip stage, the temperature of the extruder must be set to be equal to or higher than the melting point of PET. In general, the temperature is set to 280 ° C or higher in consideration of production stability. PBT is 260 ° C. or higher, and further, the decomposition rate becomes higher from around 280 ° C., so the molecular weight is reduced by the heat of the extruder. As a result, compatibility with PET is improved and the process proceeds in a more uniform direction, so that copolymerization is facilitated, and both polyesters are not copolymerized and have crystallinity suggested to be close to being independent. However, because of the mutual influence, the independence of the crystallinity at a higher level is not maintained, so that the crystallization speed cannot be improved, and as a result, the whitening at a higher level is prevented. It is inferred that this was not possible.

  Especially when a slow compression type extruder is used, when an extruder with a large compression ratio is used, and when the L / D is large (inferred to be 35 or more), the apparent set temperature can be set low, but the compression section of the extruder It seems that PTT, PBT, PHT, etc. having a low melting point are easily decomposed because the amount of self-heating in the (compression zone) increases and the temperature of the resin becomes higher than the set temperature.

  Examples of the machine base for mixing the melted polyester include a normal single screw extruder, a twin screw extruder, a dynamic mixer, a static mixer (manufactured by Noritake Company, etc.), and the like. Especially when mixing separately melted resins, so that they are not evenly mixed and compatible, when using a normal single-screw or twin-screw extruder, the one with a small compression ratio, the entire extruder screw and A compressor with a small L / D is required.

  From the above points, in the present invention, the method of mixing the respective resins after individually melting the respective raw materials is preferable. Therefore, it is preferable to use two or more extruders in parallel, but to achieve this application using a single extruder, the screw compression section (compression zone) in the single-screw extruder has a double flight type. This can be achieved by using a rapid compression type and a small compression ratio (2.0 or less). In addition, although the extruder which has a double flight type screw includes Mitsubishi Heavy Industries' UB series, it is not achieved by all of them, and it seems that the above-mentioned conditions must be satisfied. The reason is presumed as follows. The PBT where the compression part of the screw started melting because of the double flight and the PET that maintains solids at that time are separated by the first flight of the compression part, so the contact time between PET and PBT is shortened Therefore, it is guessed that it is effective. However, since this method has a narrow allowable range of conditions, a method of using two or more extruders in parallel is preferable.

  In consideration of these, in a method of preparing a film by mixing and extruding two types of resin raw materials having different configurations, the raw material A and the raw material B are respectively put into separate extruders, melted, and then in a molten state. It is necessary to feed to one mixing device, mix and extrude, preferably at least uniaxially oriented.

  As the extruder for melting and extruding the raw materials A and B, a normal single screw extruder, a twin screw extruder, or the like can be used. In addition, as a mixing apparatus for supplying the resin supplied from each extruder in a molten state, a single screw extruder, a twin screw extruder, a dynamic mixer, a static mixer, or the like can be used.

  In the present invention, the raw materials A and B may be a single raw material or a mixture. Silicon dioxide, kaolin, clay, calcium carbonate, calcium terephthalate, aluminum oxide, titanium oxide, calcium phosphate, silicone particles, stabilizers, colorants, antioxidants, antifoaming agents, antistatic agents, etc. as necessary Additives can be included. Even in the case of a mixture, preferably, the main component of each raw material is 60% or more, more preferably 80% or more, and still more preferably 90% or more is a single raw material. In the present invention, an effective production method is used when the difference between the melting points of the raw materials A and B is preferably 15 ° C. or higher, more preferably 20 ° C. or higher, and further preferably 25 ° C. or higher.

  For general packaging, antistatic property, gas barrier property, metal laminate, heat seal, anti-fogging, metal deposition, easy tear, easy opening, bag making packaging, retort packaging, boil packaging, medicine packaging, easy It can be used as a production method for adhesiveness, magnetic recording, capacitor, ink ribbon, transfer, adhesive label, stamping foil, gold and silver thread, tracing material, mold release, shrink film and the like.

  Hereinafter, specific examples will be described. In addition, each characteristic value of the polyester in an Example was measured as follows.

1. Reduced viscosity Reduced viscosity (ηsp / C)
0.125 g of polymer was dissolved in 25 ml of phenol / tetrachloroethane = 6/4 (weight ratio) and measured at 25 ° C. using an Ubbelohde viscosity tube. The unit is dl / g.

2. Melting point (TmL, TmH) of film, crystallization temperature (Tc2), and half width of crystallization peak Using DSC3100S manufactured by Rigaku Electric Co., Ltd., putting the film into a sample pan, capping the pan, and under nitrogen atmosphere Measured at a temperature increase rate of 20 ° C./min from room temperature to 280 ° C., and the peak top temperatures of the melting peaks of the melting points derived from the resin raw material A and the resin raw material B were TmH and TmL, respectively. Hold the sample as it is for 1 minute, then cool it down to room temperature at a rate of 20 ° C./min, and measure the peak top temperature of the crystallization peak as Tc2, and set the peak height h from the baseline. The half width was defined as 1 / h divided by the temperature width l at a height of 0.5 h.
(Lamination condition)
Lamination temperature 220 ℃
Linear pressure 10N / cm

3. The whitened film is laminated on an aluminum plate under the following conditions and left in a gear oven at 280 ° C. for 1 minute. After that, what was cooled by applying air at 25 ° C. to the film surface of the laminate at a wind speed of 20 m / min was judged visually.
◎ ・ ・ ・ No whitening before and after heat treatment ○ ・ ・ ・ ・ Substantially △ ・ ・ ・ ・ Whitening is observed × ・ ・ ・ Whitening is remarkable

4). Hardness 3. Sharpen the tip of the pencil lead with the film surface of the laminate processed in step 1. It is expressed by the highest pencil hardness that was not scratched at that time.

5). Can-making film 2. After being processed at 240 ° C. under the conditions described above, after processing at 240 ° C., the presence or absence of damage such as peeling, cutting, and cracking of the film after forming the can body was observed visually and with a fluorescence microscope (magnification 80 times). Evaluation based on the criteria.
◎ ... 95 out of 100 cans are not damaged.
○ ... No damage to 80-94 out of 100 cans.
Δ: ... 70 to 79 out of 100 cans were not damaged.
X: Some 31 or more out of 100 cans have some damage In the present invention, Δ is preferably obtained, and o is more preferred.

(Example 1)
6,6-nylon resin was charged into a 60 mmφ extruder (I) (L / D = 29 compression ratio 4.2) and melted at 275 ° C. 6-nylon resin was put into another 60 mmφ extruder (II) (L / D = 29 compression ratio 4.2) and melted at 240 ° C. After that, the raw materials I and II of I and II were respectively led to a 90 mmφ extruder (III) (L / D = 25 compression ratio 1.5) in the molten state so as to be 4/6 (weight ratio). Then, it was melted and extruded from a T-die to obtain an unstretched sheet having a thickness of 200 μm. At this time, the temperature of the cylinder part and the filter part (200 mesh) of the extruder III is 260 ° C., the temperature from the screw tip of the extruder to the T-die is 255 ° C., and the temperature of the resin discharged from the T-die is 257 ° C. It was made to become. The pressure of the resin immediately before entering the T-die was set to 8.8 MPa (90 kgf / cm ² ). This unstretched sheet is guided to a roll stretching machine, stretched 3.3 times at 60 ° C in the longitudinal direction, and further stretched 3.5 times at 80 ° C in the transverse direction with a tenter, and then transversely within the tenter. The film was heat-fixed at 220 ° C. while relaxing 3% to obtain a film having a thickness of 17 μm. The characteristic values are shown in Table 1.

(Comparative Example 1)
Polyester resin A (polyethylene terephthalate resin (reduced viscosity 0.75, catalyst is germanium dioxide, melting point of resin 255 ° C.) in which silicon dioxide (D) (Silicia 310 manufactured by Fuji Silysia) was added at the time of 2000 ppm polymerization, and polyester resin B (polyethylene Butylene terephthalate resin (Toray 1200S, reduced viscosity 1.30, resin melting point 225 ° C.) and organophosphorus compound (C) (Adekastab PEP-45: Asahi Denka Kogyo Co., Ltd. 300 ppm) were mixed in a weight ratio (polyester A / The polyester B) was fed into the extruder III (L / D = 25, compression ratio 4.0) as pellets so as to be 4/6, extruded under the same temperature conditions as in Example 1, and the longitudinal stretching temperature was 70 ° C. Biaxial stretching was performed in the same manner as in Example 1 except that the stretching temperature was 95 ° C. and the heat setting temperature was 150 ° C. A film was obtained during extrusion. Degrees conditions were set the same as in Example 1, but the temperature of the resin exiting from the T- die was 265 ° C..

How to find the half width of Tc2

Explanation of symbols

1 Line measured with DSC 2 Baseline 3 Peak height from baseline h
4 Height from baseline 0.5
5 Temperature range l at 0.5h above baseline

Claims (7)

  A resin raw material selected from polypropylene, polyethylene, polystyrene, polymethylpentene, cyclic olefin resin, acrylic resin, polycarbonate, polyphenylene sulfide, vinyl resin, polylactic acid and nylon resin, and resin raw materials A having two different configurations, B is melted individually, and these are fed in a molten state to any one mixing device selected from a single screw extruder, twin screw extruder, dynamic mixer and static mixer, mixed and extruded to form a film. A method for producing a resin film, comprising: The method according to claim 1, wherein the difference in melting point between the two types of resin raw materials A and B having different structures is 15 ° C. or more. The method according to claim 1 or 2, wherein the mixing device is a static mixer. The method according to claim 1, wherein the film is stretched in at least one axial direction. The method according to claim 1, wherein the film is for metal lamination or molding. For general packaging, heat sealing, bag making packaging, retort packaging, boil packaging, medicine packaging, magnetic recording, capacitor, ink ribbon, transfer, adhesive label, stamping foil, gold and silver thread The method according to any one of claims 1 to 4, wherein the method is for a tracing material, a mold release or a shrink film. At least one of the resin raw materials A and B having two different configurations contains silicon dioxide, kaolin, clay, calcium carbonate, calcium terephthalate, aluminum oxide, titanium oxide, calcium phosphate, or silicone particles, or these The method according to any one of claims 1 to 6, further comprising a stabilizer, a colorant, an antioxidant, an antifoaming agent or an antistatic agent as necessary. .

Images