JP2003073488A - Polybutylene terephthalate-based resin oriented film, multi-layered oriented film and bag-like packaging material with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oriented film excellent in appearance, inside visibility, designability or the like, including less fish-eyes with forming stability obtained by using a polybutylene terephthalate-based resin made by continuous polymerization method, and to provide a multi-layered oriented film and a bag-like packaging material with the same. SOLUTION: This oriented film is obtained by using a polybutylene terephthalate-based resin made by continuous polymerization method and contains <=20 pieces/100 cm<2> fish-eyes of >=20 μm size in a film of the resin with 50 μm thickness. The multi-layered oriented film is made by laminating the oriented film with other resin layer. The bag-like packaging material is made by heat-sealing the bottom and/or more than two sides of these oriented films.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a stretched polybutylene terephthalate resin film, a multilayer stretched film having the same, and a bag-like packaging material. For more details,
The present invention is formed by molding a polybutylene terephthalate-based resin obtained by a continuous polymerization method, has few foreign matters (fish eyes), is excellent in molding stability, particularly stretching stability, and has an external appearance, internal visibility, and designability. The present invention relates to a stretched polybutylene terephthalate-based resin film, a multilayer stretched film having the same, and a bag-like packaging material.

[0002]

2. Description of the Related Art Polybutylene terephthalate resins are
It has been widely used in the field of injection molding as an engineering plastic because it has a higher crystallization rate than polyethylene terephthalate resin and has excellent molding processability as well as mechanical properties and electrical properties. . Further, in recent years, the properties such as aroma retention and chemical resistance of polybutylene terephthalate resin have been recognized, and they have been attracting attention in the field of film molding and packaging materials. By the way, a method for producing a polybutylene terephthalate resin is a transesterification reaction between a dicarboxylic acid ester component containing an ester derivative of terephthalic acid such as dimethyl terephthalate as a main component and a diol component containing 1,4-butanediol as a main component. And a direct polymerization method through a direct esterification reaction between a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component. After the polymerization reaction (oligomerization), there are a batch polymerization process in which a polycondensation reaction for increasing the molecular weight is performed in a batch system, and a continuous polymerization process in which an esterification reaction to a polycondensation reaction are continuously performed. From the viewpoint of production cost, a continuous polymerization process using terephthalic acid and 1,4-butanediol is considered to be overwhelmingly advantageous. However, when the polymerization is carried out by a continuous polymerization process, since the polymerization plant is continuously operated for a long time (from several months to one year or more), the long-term residence in the system becomes extremely high in viscosity and the viscosity with the main product is increased. The difference becomes extremely large, and as a result, it becomes an unmelted substance during molding to become a foreign substance, or the esterification reaction catalyst deteriorates during the reaction to become insoluble in the polymer component and precipitates to form an agglomerate, and May be. These ultra-high-viscosity substances and precipitates become fine foreign substances called fish eyes that become apparent when formed into a particularly thin film, which leads to stretching breakage and extremely decreases the productivity of the film, or even forms it as a film. Even if possible, it causes undesired situations such as a decrease in mechanical strength due to the effect of foreign matter due to fish eyes, a poor appearance, a decrease in visibility of contents, and a decrease in designability due to ink splashing during printing. This has been a big problem in the field of film where printability is important.

[0003]

Under the above circumstances, the present invention has a small amount of foreign matters (fish eyes) and is stable in molding, which is obtained by molding a polybutylene terephthalate resin obtained by a continuous polymerization method. In particular, it was made for the purpose of providing a polybutylene terephthalate-based resin stretched film having excellent appearance, internal visibility, and designability, in addition to excellent stretching stability, a multilayer stretched film having the same, and a bag-like packaging material. It is a thing.

[0004]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventor has found that when a film having a predetermined thickness is used as a raw material, the number of fish eyes having a certain size or more is It has been found that the object can be achieved by using a polybutylene terephthalate-based resin having a specific value or less and less foreign matter, and the present invention has been completed based on this finding. That is, the present invention uses (1) a polybutylene terephthalate resin obtained by a continuous polymerization method, in which the number of fish eyes having a size of 20 μm or more in a film having a resin thickness of 50 μm is 20/100 cm ² or less. A polybutylene terephthalate-based resin stretched film obtained by
A multilayer stretched film obtained by laminating the stretched film according to item 1 with another resin layer, (3) A second aspect obtained by laminating at least one polybutylene terephthalate resin stretched film with a resin layer having adhesive properties The multilayer stretched film of (4), wherein the oxygen permeability in an environment with relative humidity of 0% is lower than that of the polybutylene terephthalate-based resin, and at least one layer is provided in the multi-layer. The present invention provides a stretched film, and (5) a bag-like packaging material obtained by heat-sealing the bottom and / or two or more sides of the film according to any one of items 1 to 4.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the polybutylene terephthalate resin stretched film of the present invention, a polybutylene terephthalate resin obtained by a continuous polymerization method is used as a raw material. Examples of the polybutylene terephthalate resin include a terephthalic acid and / or its ester derivative, for example, a dicarboxylic acid component containing methyl ester, ethyl ester, propyl ester and the like as a main component, and a diol containing 1,4-butanediol as a main component. The components are continuously esterified mainly in the presence of an esterification reaction catalyst,
Then, a polybutylene terephthalate resin obtained by continuously conducting a polycondensation reaction and then withdrawing it from a polymer withdrawing die can be mentioned. Here, the terephthalic acid and / or terephthalic acid ester derivative as the dicarboxylic acid component accounts for 50 mol% or more of the total dicarboxylic acid component, preferably 80 mol% or more, and 95 mol% or more. Is more preferable. In addition, 1,4-butanediol as a diol component is
It accounts for 50 mol% or more of all diol components,
It is preferably 80 mol% or more, and more preferably 95 mol% or more. In the present invention, examples of the dicarboxylic acid component other than terephthalic acid include phthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid,
Aroma such as 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl ketone dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid, and 2,6-naphthalenedicarboxylic acid Group dicarboxylic acids, 1,2-cyclohexanedicarboxylic acid,
Alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid,
Examples thereof include aliphatic dicarboxylic acids such as suberic acid, azelaic acid and sebacic acid, and their esters with methyl, ethyl, propyl alcohol and the like. They are,
You may use 1 type and may use it in combination of 2 or more type.

On the other hand, examples of diol components other than 1,4-butanediol include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, polytetramethylene ether glycol, and 1,5-pentanediol. ,
Neopentyl glycol, 1,6-hexanediol,
Aliphatic diols such as 1,8-octanediol, 1,2
-Cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-
Alicyclic diols such as cyclohexane dimethylol, xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis (4'-hydroxyphenyl) propane, aromatic diols such as bis (4-hydroxyphenyl) sulfone, etc. Is mentioned. These may be used alone or in combination of two or more. Further, for example, glycolic acid, m-hydroxybenzoic acid,
Hydroxycarboxylic acids and alkoxycarboxylic acids such as p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid and p-β-hydroxyethoxybenzoic acid,
And monofunctional components such as stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid and benzoylbenzoic acid, tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid,
One or more selected from trifunctional or higher polyfunctional components such as trimethylolethane, trimethylolpropane, glycerol and pentaerythritol and esters thereof may be used as a copolymerization component. The polybutylene terephthalate resin in the present invention is a resin obtained by continuously polymerizing a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component. A resin obtained by continuously polymerizing terephthalic acid and 1,4-butanediol as main raw materials is particularly preferable.

As the polybutylene terephthalate resin in the present invention, the intrinsic viscosity [η] measured in a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1) at a temperature of 30 ° C. is 0.6 to 3.0 dl / Those in the range of g are suitable because they are suitable for forming a film. When this [η] is less than 0.6 dl / g, the film formability is deteriorated to cause uneven thickness, and in the case of inflation molding, bubbles are not stable, which is not preferable. On the other hand, 3.0
Exceeding dl / g is not preferable because the extrusion torque becomes high, the load is applied to the equipment, and the resin leaks from the joint portion of the equipment. A more preferable intrinsic viscosity is 0.8-2.
0 dl / g, and more preferably 0.9 to 1.3 dl
/ G range. The polybutylene terephthalate resin in the present invention, the number of fish eyes of 20μm or more in size in the film of the resin thickness 50μm is resin is 20/100 cm ² or less, is 10/100 cm ² or less It is preferably a resin. If there are many fish eyes, not only the appearance of the film is bad, but also the stretching breakage frequently occurs in the stretching step in the film manufacturing process, the continuous stable productivity of the film is greatly reduced, or even if the film becomes lucky, When winding up the film, there are irregularities on the film surface,
When a bag is processed and the contents are filled with the contents, the contents do not look neat, or when printed on a film, ink bleeds to cause printing troubles, which causes problems.
The fish eye level of 20/100 cm ² or less is a level at which the above-mentioned trouble does not occur or is inconspicuous even if it occurs and there is substantially no problem. In particular, stretch break is 1
If it occurs a large number of times in a large molding apparatus, the raw material loss becomes several tens kg to several hundreds kg, and on the other hand, a double trouble that a product cannot be obtained during that time is caused, which is a serious problem from the viewpoint of productivity. If the number of fish eyes exceeds 20/100 cm ² , stretch break will occur extremely. The increase in stretch break at the number of fish eyes of 20/100 cm ² is considered to be due to the propagation of a slight stretch break in the foreign matter portion.

The method for producing the polybutylene terephthalate resin used in the present invention is basically based on the conventional continuous production method for the polybutylene terephthalate resin. That is, the dicarboxylic acid component containing terephthalic acid and / or its ester derivative as a main component and the diol component containing 1,4-butanediol as a main component are mixed at high temperature in a single or a plurality of esterification reaction tanks. Under pressure, esterification reaction under stirring, the resulting oligomer as an esterification reaction product is transferred to a polycondensation reaction tank,
It is a method in which a polycondensation reaction is continuously performed in a single or a plurality of polycondensation reaction tanks under reduced pressure and high temperature in the presence of a polycondensation reaction catalyst. As a method for producing the polybutylene terephthalate-based resin in the present invention, a method of continuously polymerizing directly using a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,4-butanediol as a main component is preferable. A method in which terephthalic acid and 1,4-butanediol are used as main raw materials and continuous direct polymerization is more preferable. The resin obtained by the polycondensation reaction is usually continuously transferred from the bottom of the polycondensation reaction tank to a polymer extraction die and extracted in a strand form, while being cooled with water or after water cooling, and then cut with a cutter to form pellets. , A chip-like granular body. Here, as the esterification reaction catalyst in the production method, for example, tetramethyl titanate, tetraisopropyl titanate,
Typical examples include titanium alcoholates such as tetrabutyl titanate, titanium phenolates such as tetraphenyl titanate, and the amount used is, for example, in the case of tetrabutyl titanate, titanium is used with respect to the theoretical yield of polybutylene terephthalate resin. The atom is usually selected in the range of 30 to 300 ppm, preferably 50 to 200 ppm.

As the esterification reaction catalyst, tin compounds, magnesium compounds, calcium compounds and the like can be used in addition to the titanium compounds. Further, as the polycondensation reaction catalyst, the esterification reaction catalyst added during the esterification reaction can be used subsequently as the polycondensation reaction catalyst. In this case, it is not necessary to add a new catalyst. The same catalyst as the esterification reaction catalyst added during the reaction may be further added. In the esterification reaction and / or polycondensation reaction, in addition to the catalyst, orthophosphoric acid, phosphorous acid, hypophosphorous acid,
Reaction aids such as phosphorus compounds such as polyphosphoric acid and their esters and metal salts, alkali metal or alkaline earth metal compounds such as sodium hydroxide, sodium benzoate, magnesium acetate and calcium acetate, 2,6-di- t-
Butyl-4-octylphenol, pentaerythrityl-tetrakis [3- (3 ', 5'-di-t-butyl-4'-
Compounds such as hydroxyphenyl) propionate], dilauryl-3,3′-thiodipropionate, thioether compounds such as pentaerythrityl-tetrakis (3-laurylthiodipropionate), triphenylphosphite, tris (nonylphenyl) ) Phosphite, tris (2,4-di-t-butylphenyl)
Other antioxidants such as phosphorus compounds such as phosphite, paraffin wax, microcrystalline wax, polyethylene wax, long-chain fatty acids and their esters represented by montanic acid and montanic acid esters, and mold release agents such as silicone oil. Additives may be present. In the case of a multi-stage continuous polymerization plant, the second-stage polycondensation tank is often a horizontal reaction tank equipped with a stirring device having a horizontal rotating shaft. In the reaction tank, the polycondensation reaction is further advanced under stirring at a temperature of usually 235 to 280 ° C., preferably 235 to 265 ° C. and a reduced pressure of usually 1333 Pa or less, preferably 667 Pa or less. In the present invention, in the continuous production method of the polybutylene terephthalate-based resin described above, in order to remove foreign matters and reduce fish eyes, the outlet of the polymer extraction die from the outlet of the first esterification reaction tank It is desirable to install a filter in the main product flow path between and to pass the main product through the filter.

Here, the filter medium constituting the filter may be any of metal wind, laminated metal mesh, metallic nonwoven fabric, porous metal plate, etc., but laminated metallic mesh or metallic nonwoven fabric is preferable from the viewpoint of filtration accuracy. Also,
The shape of the filter may be any type such as a basket type, a disc type, a leaf disc type, a tube type, a flat type cylindrical type, and a pleat type cylindrical type, but when filtering an oligomer having a low melt viscosity, Is preferably a tube type or a flat cylindrical type from the viewpoint of cleanability, etc., and when filtering a prepolymer or polymer having a high melt viscosity, from the viewpoint of pressure resistance and processing flow rate per unit area, leaf disk type Alternatively, a pleat type cylindrical type is preferable. Further, the absolute filtration accuracy of the filter is preferably in the range of 0.5 to 50 μm from the viewpoint of filtration efficiency and the like, and 0.5 to 30 μm when the oligomer having a low melt viscosity is filtered.
Is more preferable, and the range of 5 to 50 μm is more preferable when filtering a prepolymer or polymer having a high melt viscosity. Here, as the shape of the filter,
It may be any type such as a flat type, a cylinder type and a candle type. The absolute filtration accuracy is preferably in the range of 0.5 to 50 μm from the viewpoint of filtration efficiency and the like. FIG. 1 is a flow chart showing an example of the continuous production method of the polybutylene terephthalate resin according to the present invention, which contains terephthalic acid and / or its esters as main components in the raw material preparation tank 1. The raw material mixture containing the dicarboxylic acid component and the diol component containing 1,4-butanediol as a main component is supplied to the first stage esterification tank 2 and then to the second stage esterification tank 3 for esterification. React to form an oligomer. Next, this oligomer is transferred to a first-stage polycondensation tank (for example, a vertical reactor) 4 and then to a second-stage polycondensation tank (for example, a horizontal reactor) 5 to further advance the polycondensation reaction to obtain a polymer. After being generated, the polymer is transferred to a polymer extraction die 6 to extract the polymer, and a pelletizer 7 forms pellets, chips, or the like. Also,
The filter may be installed anywhere from the outlet of the first-stage esterification tank 2 to the outlet of the polymer extraction die 6, or may be installed at one place or a plurality of places. The second place is especially effective for removing foreign matter.
Polymer extraction die 6 from the outlet of the stage esterification tank 3
Of the second stage polycondensation tank 5 to the outlet of the polymer extraction die 6 is more preferable. In the present invention, the polymerization apparatus and the polymerization conditions are not limited to the above, and the point is to install foreign matter by installing a filter in the flow path of the main product of the polybutylene terephthalate resin that is continuously produced. It is important to obtain a polybutylene terephthalate resin that is removed to give a stretched film with a reduced fish eye number.

With respect to the polybutylene terephthalate resin by the continuous polycondensation method, resins having various intrinsic viscosities can be obtained mainly by changing the operating conditions of the second-stage polycondensation tank. Alternatively, when it is necessary to reduce the amount of tetrahydrofuran, which is a main side reaction product, the resin particles obtained by the continuous polymerization method are treated under an inert gas atmosphere and / or under a reduced pressure of about 13 to 1333 Pa. Usually, heating is carried out at a temperature of 5 to 50 ° C. lower than the melting point of the resin, preferably 10 to 40 ° C. lower than the melting point, while normally flowing for 5 to 20 hours while flowing so that the particles do not stick to each other. It is also possible to treat and carry out a solid-phase polycondensation reaction. In the polycondensation reaction of the polybutylene terephthalate-based resin in the present invention, even when solid phase polymerization is also used, the obtained polymer contains a lot of foreign substances unless a filter is installed in the production of the resin for solid phase polymerization, and thus the film form When it is molded into, it may cause a trouble called foreign substance mixing called a fish eye. The stretched film of the present invention can be obtained by forming the polybutylene terephthalate-based resin thus obtained into a film by a known method and further stretching the film. As a method of forming a film, for example, a molten resin is extruded into a flat plate shape and continuously drawn by a roll to form a flat plate-like film, a T die casting method, and a molten resin is continuously extruded from an annular die to adjust the internal air pressure. While inflating into a balloon shape and cooling with cold air, the air-cooled inflation method is also used, in which it is continuously extruded from an annular die and water is cooled while controlling the outer diameter with a restriction ring made of metal or the like. Although a calendar method and the like can be mentioned, a T-die casting method and an inflation method which can perform melt extrusion without contact with the outside air are preferable. In forming the multilayer film, a known multilayering device (multi-many hold T die, stack plate die, feed block, multilayer inflation die) or the like can be used to obtain the multilayer film.

When the film is formed, the resin temperature is 2
It is preferable to adjust the cylinder temperature and the die temperature so as to be about 30 to 290 ° C. The thickness of the obtained film varies depending on the purpose of use, but in the case of a monolayer film, it is usually 10 to 100 μm after stretching, and in the case of a multilayer film, it is usually 15 to 200 μm. The thickness of the film to be stretched depends on whether it is uniaxially stretched or biaxially stretched, and the stretching ratio. If the thickness of the stretched film is too thin, stretching breakage is likely to occur in the stretching process, and it becomes difficult to improve the thickness accuracy of the stretched film, resulting in large thickness unevenness of the product, which is not preferable. On the other hand, if the thickness of the stretched film is too large, there will be many problems such as the need to stretch with an excessive force in the stretching step, the load on the apparatus increases, and the stretching cannot be performed depending on the stretching method. The preferred range of thickness is 12 to 80 μm, more preferably 15 to 50 μm for the stretched monolayer film, and 20 to 120 μm for the multilayer stretched film.
m, more preferably 30 to 80 μm. The oxygen barrier property of polybutylene terephthalate resin is quite high, and even if it is as it is, it can highly prevent oxidative deterioration of the contents, but semi-raw products such as pastes and fresh raw foods that require a higher oxygen barrier property. For packaging foods and the like, resins having oxygen permeability lower than that of polybutylene terephthalate resins in an environment of 0% relative humidity, such as aliphatic nylon films such as 6-nylon and 66-nylon, aliphatic dicarboxylic acids and aromas. Group diamine chloride or a semi-aromatic nylon represented by a condensate of an aromatic dicarboxylic acid or a condensate of an aromatic dicarboxylic acid and an aliphatic diamine, a multi-layered structure with a partially saponified product of ethylene-vinyl acetate copolymer (commonly known as EVOH), and vinylidene chloride resin It is also possible to carry out processing such as a so-called K-coat coated with the above emulsion.

There is no particular restriction on the thickness of the resin having a higher oxygen barrier property than those of these polybutylene terephthalate resins when forming a multilayer, and after stretching, oxygen is provided so that the oxygen barrier property required for storage of the contents is obtained. The barrier resin and its thickness may be designed. For example, as a layer structure for packaging loin ham, polybutylene terephthalate resin (12.5%) / adhesive resin (6.3%) / 6 nylon (31.2%) / adhesive resin (6.3%) / Linear low-density polyethylene (43.7%) with an overall thickness of 40-80
μm is preferable. In addition,% in () shows the ratio of thickness. Examples of other multilayer structures include PBT / adhesive resin PBT / adhesive resin / polyethylene resin PBT / adhesive resin / polypropylene resin PBT / adhesive resin / polyamide resin / adhesive resin / polyethylene resin or polypropylene resin PBT / adhesive resin / EVOH resin / adhesive resin / polyethylene resin or polypropylene resin Polyethylene or polypropylene resin / adhesive resin /
Examples include PBT / adhesive resin. The PBT is a polybutylene terephthalate resin, and other specific examples of the resins are as follows. Polyethylene resin: Ultra low density polyethylene, low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc. Polypropylene resin: Homo PP, C4 copolymer PP, C
6 Copolymerized PP, C8 copolymerized PP, terpolymer, etc. Adhesive resin: Maleic anhydride-modified polyethylene resin, glycidyl methacrylate copolymerized polyethylene resin, glycidyl methacrylate-acrylic acid-copolymerized polyethylene resin, etc. Polyamide resin: the above-mentioned various Nylon, etc.

The stretching treatment is preferably carried out near the glass transition temperature of the polybutylene terephthalate resin to below the melting point, and the stretching ratio is 1.5 to 5 in the longitudinal and transverse directions, respectively.
A double range is preferable. If the stretching temperature is too low, stretching rupture or oriented crystallization does not occur, which is not preferable because the mechanical properties of the film are not improved. If the stretching temperature is too high, the film is whitened and strength is not exhibited, which is not preferable. If the stretching ratio is too low, stretching unevenness occurs, and a film having a uniform thickness cannot be obtained. If it is too high, stretching is broken and a film cannot be obtained. It is important to set the stretching temperature and the stretching rate within appropriate ranges. For example PBT
In the case of single layer uniaxial stretching, the stretching temperature is 50 to 75 ° C., the stretching ratio is 3 to 6 times, and in the case of single layer or multilayer simultaneous biaxial stretching, the stretching temperature is 5
It is desirable that the draw ratio is 0 to 70 ° C. and the draw ratio is 2.5 × 2.5 to 3.5 × 3.5. Usually, the stretched film is heat-set at a temperature not lower than the stretching temperature and not higher than the melting point in order to develop dimensional stability after the stretching treatment. In the case of stretching the PBT resin, the heat-setting temperature is about 200 ° C. in the case of a single layer film. In the case of a multi-layer film, the conditions are considerably different depending on the multi-layered resin, but it is advantageous to carry out in the range of 80 to 200 ° C.

When forming the film, known additives such as phenol-based, phosphorus-based, sulfur-based, amine-based and other antioxidants, silica, zeolite, talc and glass for exhibiting anti-blocking performance are used. Beads, inorganic particles such as silicone particles, crosslinked organic particles such as crosslinked PMMA and crosslinked polystyrene, calcium salts and sodium salts of fatty acids such as calcium stearate as a lubricant, polyethylene wax, esters of polyhydric alcohol, and the like. Various coloring agents and release agents may be added. These additives may be blended with the raw materials at the time of forming the film, or may be used by appropriately diluting a masterbatch adjusted to a high concentration in advance at the time of forming. Next, the bag-shaped packaging material of the present invention is obtained by heat-sealing the bottom and / or two or more sides of the thus obtained single-layer stretched film or multilayer stretched film. Specifically, when the single-layer stretched film or the multi-layer stretched film is used as a bag for packaging, it is usually a method such as heat-sealing or impulse-sealing, in which heat is applied to the laminated films to melt them and then the bags are joined together. To process. When a film is formed into a tube shape, it is possible to create a bag-like product by sealing only one direction, which is the bottom part, but when a film on a flat surface is prepared by the T-die method, it is formed into a bag. To do this, both sides of the film are sealed into a tube shape, and then the bottom is heat-sealed to form a bag, and the pillow packaging is used, or both ends and the bottom are heat-sealed to form a bag. can do. In addition, by making a bag into a long triangle, it can also serve as a squeezing bag when filled with paste or whipped cream, make a polygonal bag to give design, and collect waste liquid. It is also possible to attach a port. The polybutylene terephthalate-based resin can be heat-sealed as it is, but in order to heat-seal at a lower temperature and improve bag-making processing efficiency, the above-mentioned multilayer film (the innermost layer has a lower melting point than the outermost layer resin) Are laminated) or a single layer film is dry-laminated with a resin having a low melting point such as polyethylene using an adhesive. When these low melting point resins are used for the innermost layer, the outermost polybutylene terephthalate-based resin does not melt, so that stringing of the melted resin does not occur, and the finish of the heat-sealed portion becomes beautiful, which is desirable.

[0016]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 A terephthalic acid 1 was prepared by using the same manufacturing apparatus as that shown in FIG.
1.8 mol of 1,4-butanediol was supplied to the raw material preparation tank 1 at a temperature of 230 ° C. and a pressure of 0.101.
While being transferred to the first stage esterification tank 2 adjusted to 3 MPa, 3.14 parts by weight of tetrabutyl titanate was supplied to 100 parts by weight of the raw material, and the esterification reaction was carried out under stirring for a residence time of 2 hours, Esterification reaction rate 87.3%
The oligomer of was obtained. Subsequently, the oligomer was transferred to the second-stage esterification tank 3 adjusted to a temperature of 240 ° C. and a pressure of 0.1013 MPa, and the esterification reaction was further advanced under stirring for 1 hour to obtain an esterification reaction rate of 98.0. % Of oligomer, the oligomer was transferred to the first-stage polycondensation tank 4 adjusted to a temperature of 250 ° C. and a pressure of 6.65 kPa, and polycondensed for 2 hours to obtain an intrinsic viscosity of 0.24 dl / g.
Was obtained. Subsequently, the prepolymer was passed through a pleated cylindrical type filter having a laminated metal mesh having an absolute filtration accuracy of 20 μm as a filter medium in the middle of a pipe for transferring the prepolymer to the second-stage polycondensation tank 5, and the temperature was 260 ° C. The polymer was transferred to the second-stage polycondensation tank 5 adjusted to a pressure of 66.5 Pa, and the polycondensation reaction was further advanced under stirring for a residence time of 4 hours to obtain a polymer having an intrinsic viscosity of 1.20 dl / g. Of the polybutylene terephthalate resin pellets (PBT) by transferring them to a polymer extraction die 6 by a gear pump, extracting them in a strand shape, and cutting them with a pelletizer 7 into pellets.
-1) was produced. Here, the esterification reaction rate and the intrinsic viscosity were measured by the following methods.

Esterification reaction rate The obtained oligomer was dissolved in N, N-dimethylformamide, and the acid value was measured by conducting titration with an ethanolic aqueous solution of 0.1 mol% potassium hydroxide to determine the acid value. X
(Meq / g)] was calculated by the following formula. Esterification reaction rate = [(9.083-X) /9.083]
The viscosity of the solution was dissolved in a mixed solvent at a concentration of 1.0 g / dl of × 100 intrinsic viscosity resulting polymer phenol / tetrachloroethane (1/1 by weight) at 30 ° C. using an Ubbelohde viscometer It was determined by measuring. The obtained polybutylene terephthalate resin pellets were supplied to a single-screw extruder equipped with a T-die and having a cylinder temperature of 270 ° C., melt-extruded into a film, and then cooled to a temperature of 58 to 62 ° C. by metal cooling. By rapidly cooling with a roll, a film having a thickness of 50 μm was obtained. When the number of fish eyes was measured by the method shown below, 6.
3 pieces / 100 cm ² . Number of fish eyes About the obtained film, 10 cm square (100 cm ² )
The area of 5 was observed with a stereoscopic microscope at a magnification of 50 times, the number of fish eyes having nuclei with a size of 20 μm or more at each location was counted, and the average value was calculated. next,
This polyester resin (PBT-1) was used to supply a single-screw extruder equipped with a T-die and a cylinder temperature of 270 ° C., melt-extruded into a film, and then 25-2.
By rapidly cooling with a metal cooling roll kept at a temperature of 7 ° C., a film having a thickness of 150 μm was obtained.

This film was stretched at a stretching temperature of 50 ° C. and a stretching ratio of 4 times to obtain a T. M. A stretched film having a thickness of about 38 μm was obtained by stretching in the machine direction with a stretching machine manufactured by Long Co. The drawing success rate is shown in Table 1. Example 2 A pleated cylindrical type filter having a non-woven metal fabric having an absolute filtration accuracy of 30 μm as a filter medium was used, and the filter was provided in the middle of the piping between the second-stage polycondensation tank 5 and the polymer extraction die 6. A polybutylene terephthalate resin pellet was produced in the same manner as in Example 1 except that the second stage polycondensation tank 5 was installed and the operating conditions of the second stage polycondensation tank 5 were 255 ° C., 70 Pa, and a residence time of 2.5 hours. did. At that time, the esterification reaction rate of the oligomer at the outlet of the first stage esterification tank 2 was 87.0%, and the esterification reaction rate of the oligomer at the outlet of the second stage esterification tank 3 was 98.
1%, the intrinsic viscosity of the prepolymer at the outlet of the first-stage polycondensation tank 4 is 0.25 dl / g, and finally the intrinsic viscosity of the polymer is 0.85 dl / g and the number of fish eyes is 3.4. / 100 cm ² polybutylene terephthalate resin (P
BT-2) was obtained. PBT-2 was prepared under the same conditions as in Example 1
A film having a thickness of 35 μm was prepared, and T. M. Biaxially stretched with a long machine to obtain a thickness of 1
A stretched film of 5 μm was obtained. The drawing success rate is shown in Table 1.

Comparative Example 1 Polybutylene terephthalate resin pellets were produced in the same manner as in Example 1 except that no filter was used. At that time, the esterification reaction rate of the oligomer at the outlet of the first stage esterification tank 2 was 87.3%, and the esterification reaction rate of the oligomer at the outlet of the second stage esterification tank 3 was 98.2%. The intrinsic viscosity of the prepolymer at the outlet of the first-stage polycondensation tank 4 is 0.25 dl / g, and finally the polybutylene terephthalate resin (PBT-3) having an intrinsic viscosity of the polymer of 1.21 dl / g is obtained. It was The number of fish eyes in this resin film is 35.2 / 100 cm ²
It looked like a shark skin. Using PBT-3, film formation and stretching treatment were carried out in the same manner as in Example 1, and the stretching success rate is shown in Table 1. Examples 3 and 4 and Comparative Example 2 Using PBT-1 (Examples 3 and 4) and PBT-3 (Comparative Example 2), a 3 type 3-layer water-cooled inflation film molding apparatus (3S01 type) manufactured by Placo Co., Ltd. Layer thickness 50 μm ・ Adhesive resin layer [acid-modified polyethylene, density 0.90 g / c
m ³ , melt index (MI = 3.0 g / 10 minutes, “MODIC F534A” manufactured by Mitsubishi Chemical Co., Ltd.) Thickness 10 μm Polyolefin resin layer (density 0.924 g / cm ³ , MI
Low density polyethylene (0.7g / 10min) Thickness 40μm
A tubular three-kind three-layer water-cooled inflation film (total thickness 100 μm) was molded and stretched in the MD direction at a stretching temperature of 60 ° C. and a stretching ratio of 4 times (Example 3). Further, a stretching treatment was carried out at a stretching temperature of 60 ° C. at a stretching ratio of 3 × 3 (Example 4, Comparative Example 2). First of each drawing success rate
Shown in the table.

[0020]

[Table 1]

(Note) The drawing success rate indicates the drawing success rate when 20 sheets are drawn.

[0022]

EFFECTS OF THE INVENTION According to the present invention, by using a polybutylene terephthalate-based resin containing a small amount of foreign matter obtained by a continuous polymerization method as a raw material, fish eyes are small and molding stability, particularly stretching stability is excellent. It is possible to provide a polybutylene terephthalate-based resin stretched film having excellent appearance, internal visibility, and design.

[Brief description of drawings]

FIG. 1 is a flowchart showing an example of a continuous method for producing a polybutylene terephthalate resin according to the present invention.

[Explanation of symbols]

1 raw material preparation tank 2 1st stage esterification tank 3 2nd stage esterification tank 4 1st stage polycondensation tank 5 Second stage polycondensation tank 6 Polymer extraction die 7 pelletizer

Continued front page    F term (reference) 3E086 AB01 AB03 AC07 AC22 AD01                       BA04 BA15 BA33 BB05 BB21                       BB51 BB62 BB68 BB90 DA08                 4F071 AA45 AF08 AF27 AH04 BA01                       BB07 BC01 BC02                 4F100 AK01B AK01G AK03 AK04                       AK06 AK42A AL07 BA02                       BA07 BA10A BA10B BA15                       BA21 DA02 EJ37A GB16                       HB00 JD03B JD03G JN01                       YY00A

Claims (5)

[Claims] 1. A polybutylene terephthalate resin obtained by a continuous polymerization method, wherein the number of fish eyes having a size of 20 μm or more in a film having a resin thickness of 50 μm is 20/100 cm ² or less. A stretched film of polybutylene terephthalate resin, characterized in that 2. A multilayer stretched film obtained by laminating the stretched film according to claim 1 with another resin layer. 3. The multilayer stretched film according to claim 2, wherein a resin layer having an adhesive property is laminated on at least one side of the stretched polybutylene terephthalate resin film. 4. The multilayer stretched film according to claim 2, wherein at least one layer made of a resin having oxygen permeability lower than that of a polybutylene terephthalate resin in an environment of relative humidity of 0% is provided. 5. A bag-shaped packaging material obtained by heat-sealing the bottom and / or two or more sides of the film according to claim 1.