JP4826243B2 - Manufacturing method of plastic film - Google Patents

Description

  The present invention relates to a method for producing a plastic film using two types of resin components having different chemical compositions as raw materials and using a static mixer in the production process.

  2. Description of the Related Art Conventionally, a method for producing a film in which two or more different types of resins are melted separately and the melted resins are combined and passed through a static mixer has been proposed (for example, Patent Document 1). . These films were manufactured at a relatively small scale tester level.

By the way, in production machines for industrially producing plastic films, production with a large discharge amount is required in order to improve productivity, so that the operating conditions performed at the testing machine level can be immediately applied to the production machines. is not. Usually, production machines are required to have stricter operating conditions than test machines. For example, the shear rate of the resin in the static mixer does not exceed 2 (1 / second) in the test machine (discharge amount less than 0.3 m ³ / hour), whereas the production machine (discharge amount 0.3 m ^3). / Hour or more) is 2 (1 / second) or more, and the technology that was completed in the testing machine is also incompatible with the production machine, resulting in the manifestation of various problems that were not recognized by the testing machine. .

When a film is produced industrially by blending two kinds of resins, since a film having a substantially uniform composition is produced by transesterification, there has been almost no problem with scale-up. In industrial production of the film to be used, it is considered difficult to scale up because a multilayer (non-uniform) film is produced. For example, when the present inventors carried out a plastic film manufacturing method using a static mixer in a production machine, the obtained unstretched film and stretched film had poor appearance with streaky irregularities inside. The unevenness causes defects when surface post-processing such as printing and vapor deposition is performed. In addition, foreign matter is also generated in the film, and this foreign matter causes defects in appearance and defects when surface post-processing such as printing and vapor deposition is performed.
JP 2003-266519 A

  In view of the above circumstances, the problem to be solved by the present invention is that there is no appearance defect such as streaky unevenness and foreign matter when a plastic film manufacturing method using a static mixer is industrially implemented by a production machine. The object is to provide a method by which a plastic film can be produced.

  As a result of intensive studies by the present inventors, the above-mentioned streaky unevenness is caused by the occurrence of turbulence at the interface between the two types of resin when the two types of molten resin are merged into the static mixer. In addition, it is assumed that the above-mentioned foreign matter is generated by the molten resin staying in the process for a long time and deteriorating, and the melt viscosity ratio of the two types of resins at the time of merging and the shear rate in the static mixer are predetermined. It has been found that defects in appearance such as streaky irregularities and foreign matters in the obtained film can be effectively reduced, and the present invention has been completed.

  That is, in the present invention, two types of resins A and B having different chemical compositions are put into separate extruders and melted, and the melted resins A and B are merged and passed through a static mixer. In the method of obtaining a plastic film by sticking to a cooling roll after extrusion from a melt, the ratio ηA / ηB of the melt viscosity ηA of the resin A just before joining and the melt viscosity ηB of the resin B just before joining is set to 0. 5 to 2.0, and the shear rate γ (1 / second) of the resin in the static mixer is set to 2 to 100 (1 / second). A preferred embodiment of the method of the present invention is that the static mixer has 3 to 18 elements.

  ADVANTAGE OF THE INVENTION According to this invention, when the manufacturing method of the plastic film using a static mixer is industrially implemented with a production machine, the plastic film without an external defect, such as a stripe-shaped nonuniformity and a foreign material, can be obtained. Such a plastic film is less prone to appearance defects even when printing or vapor deposition is performed.

  In the present invention, two types of resins A and B having different chemical compositions are put into separate extruders and melted, and the melted resins A and B are merged, passed through a static mixer, and extruded from a T-die. In the method of obtaining a plastic film by making it adhere to a cooling roll and then obtaining a plastic film, the ratio ηA / ηB of the melt viscosity ηA of the resin A just before joining and the melt viscosity ηB of the resin B just before joining is 0.5 to 2.0, and the shear rate γ (1 / second) of the resin in the static mixer is set to 2 to 100 (1 / second).

The object of the present invention is to produce a plastic film at the production machine level. Production of a plastic film at the production machine level means production in the case where the amount of resin discharged from the extruder per hour is 0.3 m ³ / hour or more. Considering production efficiency, the discharge rate is preferably 0.5 m ³ / hour or more, and more preferably 1 m ³ / hour or more.

  In the present invention, two types of resins A and B having different chemical compositions are used. This is because by using the resins A and B, they are agitated inside the static mixer, and a film having a multilayered laminated structure having the advantages of the resins A and B is obtained. Resins A and B may each be composed of a single type of resin, or may be a blend resin in which two or more types of resins are mixed. In addition, “different in chemical composition” of “two types of resins A and B having different chemical compositions” means that the composition of monomers constituting each resin is different. For example, i) resin A is a resin In the case where it is configured to include a monomer unit different from that of B, ii) the resin A and the resin B are composed of a copolymer composed of the same type of monomer unit, but the ratio between the copolymerized monomer units ( When the copolymerization composition ratio) is different, iii) the resin A and the resin B are both blended resins in which the same kind of resin is mixed, but the resin A and the resin B have different resin blend ratios.

  The types of the resin A and the resin B are not particularly limited as long as they can be melt-extruded and can be formed into a film by a cooling roll. The resin A and the resin B are preferably resins that are not compatible with each other. When resins that are incompatible with each other are used as raw materials, a multilayer structure in which the resin A and the resin B are alternately laminated can be formed in the obtained film without much disturbance.

  As an example of a resin that can be used, first, a polyester having a wide application range can be given. Examples of the polyester include crystalline polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polypentamethylene terephthalate, polyhexamethylene terephthalate, and polyethylene-2,6-naphthalate (PEN). Or a polyester having a relatively high crystallinity (highly crystalline polyester) obtained by copolymerizing an acid component and / or a glycol component, which will be described later, in an amount of 10 mol% or less in 100 mol% of the acid component and / or glycol component. Can be used. Furthermore, based on polyethylene terephthalate (PET), dimer acid is copolymerized to 10 mol% or less (PET-D), or polyethylene-2,6-naphthalate (PEN) is copolymerized to 10 mol% or less of isophthalic acid. It is also possible to use. More preferred are PBT, PTT and PET-D.

  When the highly crystalline polyester is the resin A, a polyester having relatively low crystallinity may be used as the resin B. For example, based on a polyester composed of terephthalic acid as the acid component and ethylene glycol as the glycol component, the dicarboxylic acid having a difference of 5 mol% or more, preferably 6 mol% or more and less than 40 mol%, in 100 mol% of the acid component and / or glycol component Examples thereof include polyesters obtained by copolymerizing components and / or glycol components. Specific monomer components include, for example, dicarboxylic acid components such as aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, and orthophthalic acid, and aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid. And alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid. Examples of the glycol component include aliphatic diols such as propanediol, butanediol, neopentylglycol, and hexanediol; alicyclic diols such as 1,4-cyclohexanedimethanol, and aromatic diols. Among them, preferred is a copolymer of 7 mol% or more and 35 mol% or less neopentyl glycol and / or 1,4-cyclohexanedimethanol based on a polyester composed of terephthalic acid as an acid component and ethylene glycol as a glycol component. Polyester.

  Polystyrene resins are also mentioned as preferable resins. The polystyrene-based resin is styrene as a monomer component; p-, m- or o-methylstyrene, 2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene, pt-butyl. Alkylstyrenes such as styrene; halogens such as p-, m- or o-chlorostyrene, p-, m- or o-bromostyrene, p-, m- or o-fluorostyrene, o-methyl-p-fluorostyrene Halogenated alkyl styrene such as p-, m- or o-chloromethyl styrene; alkoxy styrene such as p-, m- or o-methoxy styrene, p-, m- or o-ethoxy styrene; Carboxyalkylstyrenes such as m- or o-carboxymethylstyrene; alkyl ethers such as p-vinylbenzylpropyl ether Emissions; p-trimethylsilyl styrene alkylsilyl styrene; vinyl benzyl dimethoxyphosphinyl sulfide or the like using one or more, a polymer obtained by a known radical polymerization or the like. A copolymer of acrylonitrile and a styrene monomer, an ABS resin, or the like can also be used. These polystyrene resins can be used in any of a syndiotactic structure, an atactic structure, and an isotactic structure.

  Polyolefin resins can also be preferably used. The polyolefin-based resin is one kind of α-olefin having about 3 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methylpentene, 1-decene or the like. A polymer containing two or more monomer components. Moreover, you may use the cyclic olefin which has an ethylenically unsaturated bond and an alicyclic structure as 1 type of a monomer component. Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and a cycloalkane structure is preferable from the viewpoint of mechanical strength, heat resistance, and the like. The number of carbon atoms constituting the alicyclic structure is preferably 4 to 30, and the proportion of the repeating unit having the alicyclic structure is preferably 50% by mass or more. Specific examples of the alicyclic structure-containing polymer include, for example, (1) a norbornene polymer, (2) a monocyclic olefin polymer, (3) a cyclic conjugated diene polymer, and (4) a vinyl alicyclic ring. And a hydrocarbon-based polymer, and hydrogenated products thereof.

  Polyacrylic resins can also be used. Polyacrylic resins include acrylic acid, methacrylic acid, lower alkyl esters thereof (for example, esters such as methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, 2-ethylhexyl), hydroxymethyl (meth) acrylate In this case, the main component is a (meth) acryloyl group-containing monomer such as glycidyl (meth) acrylate, and radical polymerization is carried out with another vinyl monomer (such as the styrene monomer) as necessary.

  Further, nylons such as nylon 6, nylon 66, nylon 9, nylon 6-10, nylon 11, nylon 12, nylon 6T, nylon 6T / 6I and nylon 6I can also be used.

  In the production method of the present invention, first, two types of resins A and B having different chemical compositions are charged into separate extruders and melted. Prior to feeding into the extruder, the resin may be dried under heating and / or vacuum as necessary. In an extruder for melting, it is necessary to appropriately adjust the melting temperature of the resin according to the melting point, glass transition temperature, softening temperature, etc. of the resin, but the resin can be discharged from the extruder in a molten state. Therefore, it is necessary to determine the thermal degradation. As a guide, when the resin used is polyester, nylon, polystyrene resin, or polyacrylic resin, the viscosity as a molten resin at a shear rate of 20 (1 / second) is about 200 to 700 Pa · s, and the resin is polyolefin. In the case of a resin, the temperature may be set to about 300 to 1200 Pa · s. In the case of a crystalline resin, a temperature about 10 to 40 ° C. higher than the melting point of the resin may be used as a guide.

  Resins A and B melted by the extruder are joined together in the molten state. “Merging” means that resin A and resin B come into contact with each other in the same flow path. The merging may be performed before charging into the static mixer or may be performed at the moment when charging into the static mixer. Further, a feed block may be disposed immediately before the static mixer.

  FIG. 1 shows a schematic diagram of a typical apparatus for carrying out the method of the present invention. Gear pumps A and B are connected to the outlets of the extruder A for the resin A and the extruder B for the resin B, respectively, and the feed block is connected by piping. The feed block is connected to the inlet of the static mixer. In this apparatus, the joining of the resin A and the resin B is performed in the feed block. In addition, when not using a feed block, it is good to make it merge by static mixer inlet side piping.

  In the method of the present invention, the ratio ηA / ηB between the melt viscosity ηA of the resin A and the melt viscosity ηB of the resin B immediately before the merge (when reaching the feed block inlet) needs to be 0.5 to 2.0. . When a plastic film manufacturing method using a static mixer is industrially carried out by a production machine, streaky unevenness generated in the resulting film has a large difference in melt viscosity between separately melted resins. It is presumed that the disturbance occurs at the contact interface at the moment when the resins of the seeds join (contact). However, by setting the ratio ηA / ηB within the above range, the generation of the disturbance of the interface is reduced. As a result, it is possible to suppress the occurrence of streaky unevenness in the obtained film. The lower limit of ηA / ηB is more preferably 0.53, and the upper limit is 1.9. In addition, when blending 2 or more types of polymers as the resin A or B, a value obtained by measuring the melt viscosity of each polymer and arithmetically averaging the values may be used as the melt viscosity of the resin.

  The amount of the resin A and the resin B at the time of merging, that is, the ratio of the discharge amount of the extruder A and the extruder B may be appropriately selected according to the intended characteristics of the obtained film, but A / B = It is preferable to set it as 95 / 5-5 / 95, and 85 / 15-15 / 85 is a more preferable range.

The joined resins are laminated or mixed by a static mixer in a molten state. The static mixer is an element in which a rectangular plate is twisted 180 degrees alternately in a resin flow path, and the number of layers doubles each time one element passes through this element. Therefore, logically, when passing through n elements, it becomes a ²ⁿ layer or a ^{2n + 1} layer, but in reality, it may change depending on the relationship between the flow path diameter, the discharge amount, the viscosity and surface tension of each resin, etc. .

  The size of the element of the static mixer is preferably 1 to 3, and more preferably 1.5 in terms of L / D ratio (ratio represented by the length of one element / mixer inner diameter). Although the plate | board thickness of the part twisted is not specifically limited, About 2-6 mm is preferable. The number of elements inside the static mixer is preferably 3-18, and more preferably 6-14. If the amount is too small, the function as a multilayer film cannot be exhibited. If the amount is too large, the performance is not different from that of a film produced by simply blending.

In the present invention, it is important to set the shear rate γ (1 / second) of the merged molten resins A and B in the static mixer to 2 to 100 (1 / second). When a plastic film manufacturing method using a static mixer is industrially carried out by a production machine, it is assumed that the foreign matter generated in the resulting film is generated by the molten resin staying in the process for a long time and deteriorating. Is done. Therefore, the generation of this foreign matter can be suppressed by setting the shear rate in the static mixer to 2 or more. Further, if the shear rate exceeds 100 (1 / second), it becomes difficult to control the pressure in the extrusion process, or it is necessary to make the pressure resistant specification, which increases the cost of production equipment and is not economically preferable. . The lower limit of γ (1 / second) is preferably 3, more preferably 5, more preferably 8, and the upper limit of γ (1 / second) is preferably 90, more preferably 70, still more preferably 50. is there. The shear rate is defined as a velocity gradient when a viscous fluid passes between parallel plates. The pipe having a circular cross section, that is, the shear rate inside the static mixer is determined by the cross sectional area of the pipe of the mixer in which the element is disposed (the radius is r (mm)) and the amount of resin Q (mm ³ / mm) flowing in the mixer. Second). The amount of resin flowing in the mixer may be the sum of the discharge amounts of the extruder A and the extruder B. Since the shear rate γ (1 / second) in the mixer is 4Q / πr ³ , the discharge amounts of the extruders A and B and the inner diameter of the static mixer may be set so that this value falls within the above range. In order to make the discharge amounts of the extruders A and B constant, it is preferable to use a highly quantitative gear pump, and a pump having a helical type gear or a pump having two stages of gears in parallel is preferable. .

  The resin A and the resin B are usually at different temperatures in order to obtain an appropriate melt viscosity. In order to prevent thermal deterioration inside the static mixer, it is preferable to set the temperature below the temperature of the high temperature resin. The lower limit of the temperature is not particularly limited as long as there is no problem with the fluidity of the resin. When the number of elements of the static mixer is large (when the mixer is long), it is preferable to provide multiple temperature control units because precise control is possible. The total length of the static mixer may be the same, or the temperature may be reduced toward the downstream side. It may be controlled so as to go down. Lowering the temperature is effective in suppressing thermal degradation of the resin. The lowering temperature is preferably 10 ° C. or lower. In addition, the fluidity of the resin on the high temperature side is not substantially a problem as long as the residence time in the static mixer is about 10 minutes or less.

  The molten resin laminated or mixed by the static mixer is guided to a T-die, extruded from the T-die onto a cooling roll, and formed into a cast film. When extruding the molten resin onto the cooling roll, it is preferable that the molten resin is brought into close contact with the cooling roll by electrostatic force using electrodes such as a wire shape, a tape shape, a needle shape, or a knife shape and rapidly solidified. The surface temperature of the cooling roll may be selected according to the types of the resin A and the resin B to be used, which is usually adopted in the production of the resin film. Further, an air knife method may be adopted.

  In the resin path from the extruder to the T-die, it is necessary to prevent pressure loss. If a significant pressure loss occurs in the path, it is not preferable because a turbulent flow of resin occurs in that portion, and a deteriorated product is likely to be generated, or the laminated structure of the film is disturbed. In addition, temperature control in the extruder, gear pump, static mixer, T-die, and piping between these devices is PID control (proportional operation P, integral operation I) that can be controlled more precisely than normal on / off control. The differential operation D) is preferably performed. In addition, you may interpose a filter suitably between these apparatuses.

  The obtained cast film may be stretched uniaxially or biaxially as necessary. The stretching direction (longitudinal direction, lateral direction) for uniaxial stretching and the method (simultaneous stretching, sequential stretching) for biaxial stretching may be appropriately determined according to the characteristics required for the obtained film. Further, the stretched film may be subjected to heat treatment in order to impart flatness and dimensional stability.

  When the production method described above is employed and a film is produced under the same conditions, a film having a relatively uniform multilayer structure can be obtained even on an industrial scale. In addition, when obtaining a film, you may add a well-known additive.

  Films industrially obtained by the method of the present invention have no defects in appearance, have good finishes such as printing and vapor deposition, and are used for various food packaging, general industrial, optical, electrical materials, and molding processes. Used as a film. Specifically, for general packaging, antistatic, gas barrier, metal laminating, heat sealing, antifogging, metal deposition, easy tearing, easy opening, bag making packaging, retort packaging, boil packaging, medicine packaging It is suitable for application, easy adhesion, magnetic recording, capacitor, ink ribbon, transfer, adhesive label, stamping foil, gold and silver thread, tracing material, mold release, shrink film and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited to these Examples at all. First, the evaluation method of the film created in the Example and the comparative example is demonstrated.

(1) Melt Viscosity The melt viscosity at the resin temperature immediately before joining the static mixer was measured using a capillograph (manufactured by Toyo Seiki Co., Ltd .; model CAPILOGRAPH 1B). The shear rate γ at the time of viscosity measurement was 20 (1 / second), and measurement was performed using a capillary having an inner diameter of 1 mmφ and a length of 10 mm.

(2) Shear rate As described above, from the radius r (mm) of the static mixer and the amount of resin Q (mm ³ / sec) flowing through the mixer (the total discharge amount of the extruder A and the extruder B), The shear rate γ = 4Q / πr ³ was calculated.

(3) Appearance of the film The film is cut into a 15 cm square, placed on a black mount, and the film on the mount is held over a white fluorescent lamp ("FLR40S" manufactured by Toshiba; three-wavelength type; two are arranged in parallel). Considering the case where the fluorescent lamp and the film are parallel to each other as 0 degree, the film is tilted by 20 to 80 degrees, the fluorescent lamp is reflected on the film, and unevenness inside the film is visually observed. The case where a plurality of linear irregularities were seen inside the film was indicated as x, the case where it was slightly (about 1) visible, and the case where no irregularities were observed at all, as ○.

(4) Foreign matter A film having a length of 1000 m or more is manufactured, 10 observation points are provided for every 100 m in the length direction, and a 1 m ² film is cut out at each observation point. If one or more were recognized, it was marked as x.

Synthesis Example 1 (Synthesis of polyester)
In an esterification reactor, 57036 parts by mass of terephthalic acid (TPA), 33244 parts by mass of ethylene glycol (EG), 15733 parts by mass of neopentyl glycol (NPG), 23.2 parts by mass of antimony trioxide (polymerization catalyst) , 5.0 parts by weight of sodium acetate (alkali metal compound) and 46.1 parts by weight of trimethyl phosphate (phosphorus compound) were charged, the pressure was adjusted to 0.25 MPa, and the mixture was stirred at a temperature of 220 to 240 ° C. for 120 minutes. The reaction was carried out. The reaction vessel was restored to normal pressure, 3.0 parts by mass of cobalt acetate tetrahydrate and 124.1 parts by mass of magnesium acetate tetrahydrate (alkaline earth metal compound) were added, and the temperature was 240 ° C. for 10 minutes. After stirring, the pressure was reduced to 0.5 hPa over 75 minutes and the temperature was raised to 280 ° C. Stirring was continued until the melt viscosity reached 4500 poise at a temperature of 280 ° C. (about 70 minutes), and then discharged into water in the form of a strand. The discharged material was cut with a strand cutter to obtain a polyester chip a. The intrinsic viscosity of the polyester chip a was 0.75 dl / g.

  The intrinsic viscosity was precisely weighed with 0.1 g of a chip, dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane = 3/2 (mass ratio), and then measured with an Ostwald viscometer at 30 ± 0.1 ° C. . The intrinsic viscosity [η] is obtained by the following formula (Huggins formula).

Here, η _sp : specific viscosity, t ₀ : solvent dropping time using Ostwald viscometer, t: film solution dropping time using Ostwald viscometer, and C: film solution concentration. In the actual measurement, the intrinsic viscosity was calculated by the following approximate equation where k = 0.375 in the Huggins equation.

Here, η _{r is the} relative viscosity.

Synthesis example 2
Polyester raw material chips b to having the chip composition shown in Table 1 were obtained in the same manner as in Synthesis Example 1. In the table, NPG is neopentyl glycol, DEG is diethylene glycol, PD is 1,3-propanediol, CHDM is 1,4-cyclohexanedimethanol, and BD is 1,4-butanediol.

Example 1
The film was manufactured with the manufacturing apparatus shown in FIG. Each chip obtained in the above synthesis example is separately preliminarily dried, and chip a and chip b are placed at a ratio of 8: 2 (mass ratio) in a hopper (not shown) immediately above the extruder A and a fixed screw feeder (not shown). The mixture was mixed in the hopper and continuously melted and extruded with a single screw extruder A at 275 ° C. ± 2 ° C. (resin A). In this extruder A, the shaft was 200 mmφ, L / D = 25, and the discharge amount was 0.972 m ³ / hour (= 1268 kg / hour).

Separately, chip a and chip b are fed into the hopper (not shown) directly above the extruder B at a ratio of 2: 8 (mass ratio), separately and continuously with a fixed screw feeder (not shown). And melt extrusion with a single screw extruder B (resin B) at 255 ° C. ± 2 ° C. In this extruder B, the shaft was 100 mmφ, L / D = 25, and the discharge amount was 0.243 m ³ / hour (= 317 kg / hour).

  The resin melted by both extruders is led to a feed block at 265 ° C. ± 2 ° C. so that resin A / resin B = 8/2 (discharge amount ratio), and further, a static mixer (Noritake, 265 ° C. ± 2 ° C.) 12 elements) manufactured by the company were passed through a T-die at 265 ° C. ± 2 ° C. and melt extruded into a film. The gear pump used was a type in which helical gears having grooves cut diagonally were arranged in two stages in parallel. The static mixer element is a 180 mm twisted metal plate with a thickness of 4 mm, and has a length (equivalent to the inner diameter of the mixer) of 68.2 mm and a length of 102.3 mm (L / D = 1.5). Using. When connecting the elements, the nth end face and the (n + 1) th end face were connected so as to be orthogonal to each other at 90 degrees. The odd-numbered elements were twisted clockwise and the even-numbered elements were twisted counterclockwise. Temperature control in all apparatuses was performed by PID control.

The total extrusion amount of the resins A and B is 1.215 m ³ / hour (corresponding to 1580 kg / hour), and the inner diameter of the mixer is 68.2 mm (2r). Therefore, the shear rate γ in the mixer is 10.8. (1 / second).

  The extruded resin was electrostatically adhered onto a cooling roll having a surface temperature of 25 ° C. ± 2 ° C. to obtain an unstretched cast film. The unstretched cast film was preheated at 75 ° C. with a metal roll as it was, and then stretched 1.1 times at 80 ° C. with a silicone rubber roll. The longitudinally stretched sheet was preheated at 82 ° C. for 24 seconds in a tenter, and subsequently stretched 4.8 times at 77 ° C. in the transverse direction, followed by heat treatment at 70 ° C. for 24 seconds, resulting in a heat shrinkage of 45 μm in thickness. A conductive polyester film was obtained. Table 2 shows the appearance of the stretched film and the occurrence of foreign matter.

  Here, in Example 1, the fluctuation range of the temperature of the film surface when the film was continuously produced was as follows: average temperature ± 1.5 ° C. in the tenter preheating step, average temperature ± 2.5 ° C. in the stretching step, heat treatment The average temperature in the process range was ± 2.0 ° C.

Comparative Example 1
An unstretched cast film was obtained in the same manner as in Example 1, except that the total discharge amount of the resin in Example 1 was 0.213 m ³ / hour (277 kg / hour). The cast film was not stretched because the appearance was poor and many foreign substances were generated.

Comparative Example 2
An unstretched cast film was obtained in the same manner as in Example 1 except that the inner diameter of the static mixer was 120.0 mm. The cast film was not stretched because the appearance was poor and many foreign substances were generated.

Comparative Example 3
A stretched film was obtained in the same manner as in Example 1 except that the temperature of the resin A was 225 ° C. Table 2 shows the appearance of the stretched film and the occurrence of foreign matter.

Reference example (film formation experiment with an experimental machine)
A single screw extruder (60 mmφ, L / D = 25) having a small scale was used instead of the extruder A in Example 1, and a twin screw extruder (22.5 mmφ × 2, L / D) was used instead of the extruder B. Resins A and B were extruded and passed through a static mixer in the same manner as in Example 1 except that D = 25) was used. The total discharge amount was 0.03 m ³ / hour. In the static mixer, the number of elements was the same as that in Example 1 (12), but the length was 38.4 mm and L / D = 1.5. After passing through the static mixer, an unstretched cast film was obtained in the same manner as in Example 1, preheated, stretched and heat-set, and a heat-shrinkable polyester film having a thickness of 45 μm was obtained. Table 2 shows the appearance of the stretched film and the occurrence of foreign matter.

  In the experimental machine, since the discharge amount was smaller than that in the production machine, the shear rate in the mixer was low, but the appearance of the film was good and no foreign matter was observed.

Example 2
Using the chips c and b obtained in the above synthesis example, a film was produced using the same film production apparatus as used in Example 1. Chips c and b were separately preliminarily dried and melt-extruded with a single screw extruder A at 280 ° C. ± 2 ° C. while continuously feeding the chip c to the hopper directly above the extruder A with a quantitative screw feeder. (Resin A). The discharge rate of the extruder A was set to 1.004 m ³ / hour (= 1306 kg / hour).

Separately, the chips b were melt-extruded by a single screw extruder B at 255 ° C. ± 2 ° C. (resin B) while being continuously supplied to a hopper directly above the extruder B by a fixed screw feeder. The discharge amount of the extruder B was 0.251 m ³ / hour (= 326 kg / hour).

The resin melted by both extruders was made resin A / resin B = 8/2 (discharge amount ratio), and after passing through the feed block and the static mixer in the same manner as in Example 1, from the T-die It was melt extruded into a film. In this example, the total extrusion amount of the resins A and B was 1.255 m ³ / hour (corresponding to 1632 kg / hour), so the shear rate γ in the mixer was 11.2 (1 / second). It was.

  The extruded resin was electrostatically adhered onto a cooling roll having a surface temperature of 25 ° C. ± 2 ° C. to obtain an unstretched cast film. The unstretched cast film was preheated in a tenter at 82 ° C. for 24 seconds and subsequently stretched 4.8 times at 77 ° C. in the transverse direction, followed by heat treatment at 70 ° C. for 24 seconds to obtain a 45 μm thick heat. A shrinkable polyester film was obtained. Table 2 shows the appearance of the stretched film and the occurrence of foreign matter.

  In Example 2, when the film was continuously produced, the fluctuation range of the film surface temperature was the average temperature ± 1.0 ° C. in the tenter preheating step, the average temperature ± 1.0 ° C. in the stretching step, and the average in the heat treatment step. The temperature range was ± 1.5 ° C.

Example 3
Using the chips d and e obtained in the above synthesis example, a film was produced with the same film production apparatus as used in Example 1. Chips d and e were separately preliminarily dried, and melt-extruded with a single screw extruder A at 250 ° C. ± 2 ° C. while continuously feeding the chips d to the hopper directly above the extruder A with a fixed screw feeder ( Resin A). The discharge amount of the extruder A was 0.783 m ³ / hour (= 1065 kg / hour).

Separately, the chips e were melt-extruded by a single screw extruder B at 285 ° C. ± 2 ° C. (resin B) while being continuously supplied to a hopper directly above the extruder B by a fixed screw feeder. The discharge amount of the extruder B was 0.522 m ³ / hour (= 710 kg / hour).

The resin melted by both extruders was made resin A / resin B = 6/4 (discharge amount ratio), and after passing through the feed block and the static mixer in the same manner as in Example 1, from the T-die It was melt extruded into a film. In this example, since the total extrusion amount of the resins A and B was 1.305 m ³ / hour (corresponding to 1775 kg / hour), the shear rate γ in the mixer was 11.6 (1 / second). It was.

  The extruded resin was electrostatically adhered onto a cooling roll having a surface temperature of 25 ° C. ± 2 ° C. to obtain an unstretched cast film. The unstretched cast film was preheated at 60 ° C. with a metal roll as it was, and subsequently stretched longitudinally at 65 ° C. with a silicone rubber roll at 3.2 times. The longitudinally stretched sheet was preheated in a tenter at 82 ° C. for 24 seconds, subsequently stretched 3.8 times in the transverse direction at 90 ° C., then heat treated at 210 ° C. for 10 seconds, and biaxially stretched with a thickness of 20 μm. A polyester film was obtained. Table 2 shows the appearance of the stretched film and the occurrence of foreign matter.

  In Example 3, when the film was continuously produced, the fluctuation range of the film surface temperature was as follows: the average temperature ± 1.0 ° C. in the tenter preheating step, the average temperature ± 1.0 ° C. in the stretching step, and the heat treatment step. The average temperature was in the range of ± 1.5 ° C.

Example 4
A film was produced with the same film production apparatus used in Example 1. While the pre-dried nylon 6 resin (RV = 2.8: manufactured by Toyobo Co., Ltd.) is continuously fed to the hopper directly above the extruder A with a fixed screw feeder, the single screw extruder A at 245 ° C. ± 2 ° C. Melt extruded (Resin A). The discharge rate of the extruder A was 0.907 m ³ / hour (= 1042 kg / hour).

Separately, while preliminarily dried nylon 66 resin (RV = 3.2: manufactured by Toyobo Co., Ltd.) is continuously fed to the hopper directly above the extruder B with a quantitative screw feeder, a single-screw extruder at 275 ° C. ± 2 ° C. B was melt-extruded (resin B). The discharge amount of the extruder B was 0.389 m ³ / hour (= 447 kg / hour).

  The relative viscosity (RV) of nylon 6 resin and nylon 66 resin was measured according to Section 4.4 of JIS K6920-1 (2000 edition).

Resin melted by both extruders was made resin A / resin B = 7/3 (discharge amount ratio), and after passing through a feed block and a static mixer in the same manner as in Example 1, from the T-die It was melt extruded into a film. In this example, the total extrusion amount of the resins A and B was 1.295 m ³ / hour (corresponding to 1489 kg / hour), so the shear rate γ in the mixer was 11.6 (1 / second). It was.

  The extruded resin was electrostatically adhered onto a cooling roll having a surface temperature of 25 ° C. ± 2 ° C. to obtain an unstretched cast film. The unstretched cast film was preheated at 50 ° C. with a metal roll as it was, and then stretched longitudinally at a silicone rubber roll at 3.2 times at 55 ° C. The longitudinally stretched sheet was preheated in a tenter at 82 ° C. for 24 seconds, subsequently stretched 3.8 times in the transverse direction at 100 ° C., then heat treated at 210 ° C. for 10 seconds, and biaxially stretched with a thickness of 20 μm. A nylon film was obtained. Table 3 shows the appearance of the stretched film and the occurrence of foreign matter.

  In Example 4, when the film was continuously produced, the fluctuation range of the film surface temperature was as follows: the average temperature ± 1.0 ° C. in the tenter preheating step, the average temperature ± 1.0 ° C. in the stretching step, and the heat treatment step. The average temperature was in the range of ± 1.5 ° C.

Example 5
In the apparatus used in Example 1, a film was manufactured with the same film manufacturing apparatus except that the static mixer was replaced with one having an inner diameter (2r) of 41.2 mm. While supplying a pre-dried polypropylene resin (trade name “WF577-PG”; MFR = 3.3; manufactured by Sumitomo Chemical Co., Ltd .; abbreviated as PP in Table 3) continuously to the hopper directly above the extruder A with a quantitative screw feeder. Then, it was melt-extruded with a single screw extruder A at 260 ° C. ± 2 ° C. (Resin A). The discharge amount of the extruder A was 0.16 m ³ / hour (= 148 kg / hour).

Separately, the previously dried polypropylene resin “WF577-PG” and the low density polyethylene resin (trade name “F412” manufactured by Sumitomo Chemical Co., Ltd .; abbreviated as PE in Table 3) are 7: 3 (mass ratio). As described above, while continuously feeding separately to the hopper just above the extruder B with a fixed screw feeder, mixing in this hopper (abbreviated as PP + PE in the table), and at 275 ° C. ± 2 ° C. with a single screw extruder B Melt extruded (Resin B). The discharge amount of the extruder B was set to 0.16 m ³ / hour (= 148 kg / hour).

Except that a static mixer having an inner diameter (2r) of 41.2 mm was used, the resin melted in both extruders was made to be resin A / resin B = 5/5 (discharge amount ratio) in the same manner as in Example 1. After passing through a feed block and a static mixer, it was melt extruded from a T-die into a film. Since the total extrusion amount of the resins A and B was 0.32 m ³ / hour (corresponding to 295 kg / hour), the shear rate γ in the mixer having an inner diameter of 41.2 mm was 12.9 (1 / second). . The extruded resin was electrostatically adhered onto a cooling roll having a surface temperature of 25 ° C. ± 2 ° C. to obtain an unstretched polypropylene film. Table 3 shows the appearance of the unstretched film and the state of occurrence of foreign matter.

Example 6
A heat-shrinkable polyester film was obtained in the same manner as in Example 1 except that the gear pump was not used. No foreign matter was observed and the evaluation was good, but the appearance was △ because some unevenness was found.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a method for industrially implementing a plastic film manufacturing method using a static mixer by a production machine. The resulting plastic film has no defects in appearance and has a good finish such as printing and vapor deposition, so it can be used as a film for various food packaging, general industrial use, optical use, electrical material use and molding processing. .

It is a schematic diagram of the example of an apparatus for implementing this invention method.

Claims (2)

Two types of resins A and B having different chemical compositions are put into separate extruders, melted, and the melted resins A and B are merged, passed through a static mixer, extruded from a T-die, and then cooled rolls. In a method of obtaining a plastic film by making a cast film by closely adhering to
The ratio ηA / ηB of the melt viscosity ηA of the resin A just before joining and the melt viscosity ηB of the resin B just before joining is 0.5 to 2.0,
A method for producing a plastic film, wherein the shear rate γ (1 / second) of the resin in the static mixer is set to 2 to 100 (1 / second).   The method for producing a plastic film according to claim 1, wherein the number of elements of the static mixer is 3 to 18.

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