JP2000211008A - Preparation of pearl lustrous synthetic paper of biaxially orientated polypropylene(bopp) with thickness of 25-250 micron obtained by three-layer coextrusion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily prepare a pearl lustrous synthetic paper by a method wherein extrusions extruded from a screw main extruder with a feeder and screw sub-extruders with two feeders are mixed together to obtain a three-layer sheet through a T-die head and cooling molding, biaxially drawing and corona treatment are applied. SOLUTION: An extruder apparatus 1 consisting of a twin-screw main extruder and two twin-screw sub-extruders respectively with a side feeder is provided and extrusions of a polypropylene resin and an inorg. substance are mixed together and are guided into a T-die head, where they are co-extruded at a temp. of 180-280 deg.C to obtain a three-layer sheet and after this is then cooled and molded by means of a cooling molding roll device 2, it is guided into a longitudinal direction drawing device 3 and it is drawn at two steps at a low speed and a high speed to give a longitudinal strength to a synthetic paper. In addition, after the paper sheet is drawn in the transverse direction by means of a transverse drawing device 4, corona treatment is performed thereon by means of a corona treatment device 5 and a pearl lustrous synthetic paper obtd. is wound by means of a winding device 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a biaxially stretched polypropylene pearl glossy synthetic paper having a thickness of 25 to 250 μm obtained by a three-layer coextrusion method, and in particular, has a feeder by the three-layer coextrusion method. The mixed extrudate of the polypropylene resin and the inorganic material extruded from one twin screw main extruder and two twin screw sub-extruders having a feeder is combined, and one T
After passing through a die head, it is made into a three-layer sheet of a paper-like layer or a resin layer / foamed intermediate layer / a paper-like layer or a resin layer, and further cooled and formed.
After steps such as biaxial stretching, corona treatment and winding,
Three layers of paper-like layer / foamed intermediate layer / paper-like layer having a thickness of 25 to 250 microns Coextruded double-sided paper-like surface Pearl gloss synthetic paper, three-layer coextruded single-sided paper-like layer / foamed intermediate layer / resin layer Paper-like pearly glossy synthetic paper, refers to the production of a three-layer coextruded double-sided glossy pearly glossy synthetic paper of resin layer / foaming intermediate layer / resin layer, which is used as a synthetic paper for application.

[0002]

2. Description of the Related Art Polyolefin synthetic paper is currently replacing natural pulp paper. A biaxially-stretched polypropylene film is used as the base layer (intermediate layer).
A synthetic paper having a paper-like layer of a uniaxially stretched polypropylene film containing 65% by weight of inorganic fine powder has been filed and put to practical use. Oji Yuka Synthetic Paper Co., Ltd.
794, JP-A-56-141339, JP-A-56-141339
No. 118437 and Japanese Patent Application Laid-Open No. 3-87255 have been filed.

[0004]

In these production methods, a base material layer is placed between a longitudinal stretching device and a transverse stretching device, and two extruders are used to form upper and lower films, and a paper-like layer is formed. It is completed. The paper-like layer can be stretched only in the transverse direction, and the strength of the paper-like layer is low. Since the inorganic fine powder added to enhance the printability of the paper-like layer falls off in the printing process, it is necessary to clean the printing device. In addition, the paper-like layer obtained by uniaxial stretching and the base layer obtained by biaxial stretching have different total stretching ratios. Therefore, when heated, the shrinkage ratios of the paper-like layer and the base material layer also differ, and It deforms into a wave shape. Furthermore, in order to enhance the stability of the manufacturing process and product quality, the production speed of the paper-like layer, in which the upper and lower films are completed by two extruders, is limited, and the width of the finished product after stretching is only up to 6 meters. Absent. Since the thickness of a single paper layer needs to be at least 10 microns (typically 30 microns), the thickness of the product will always be 60 microns or more. Otherwise, the thickness of the product will be uneven, which will affect the printing process. As a whole, the manufacturing process is difficult and the production cost is high, making it difficult for products to spread and its application to be difficult.

[0005]

In order to solve the above-mentioned problems, the present applicant proposes a new method for producing a three-layer synthetic paper. The synthetic paper is composed of a paper-like layer or a resin layer / a foamed intermediate layer / a paper-like layer or a resin layer, and the polypropylene resin mixture of the foamed intermediate layer is formed from a twin screw main extruder having one feeder into a paper-like layer. Alternatively, the resin mixture of the resin layer is respectively extruded from a twin screw sub-extruder having two feeders, these extrudates are merged, formed into a three-layer sheet via one T-die head, and further cooled, biaxially stretched, Through steps such as corona treatment and winding, a three-layer coextruded single / double-sided paper-like surface and a double-sided glossy pearl glossy synthetic paper having a thickness of 25 to 250 microns are obtained. The production method of the present invention employs a three-layer coextrusion method. The combined paper obtained by co-extrusion after extruding the extrudates of each layer and further biaxially rolling is obtained by attaching a uniaxially stretched paper-like surface to a biaxially stretched intermediate layer by a conventional method. It differs from paper in both structure and manufacturing method. At the same time, the raw material extruded from the sub-extruder is selected from a paper-like layer using an inorganic filler and a resin layer to which no inorganic filler is added, so that the three layers of paper-like layer / foamed intermediate layer / paper-like layer can be used. Extruded double-sided paper-like surface pearl glossy synthetic paper, three-layer coextruded paper-like layer / foamed intermediate layer / resin layer Single-sided paper-shaped surface pearly glossy synthetic paper, three-layer coextruded resin layer / foamed intermediate layer / resin layer A glossy pearly glossy synthetic paper can be manufactured and used as a coated paper for synthetic paper for application.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In order to clearly show the technical contents of the present invention, a polypropylene resin mixture and production steps (extrusion, three-layer coextrusion, cooling, biaxial stretching, corona treatment, winding) will be described below. The biaxially oriented polypropylene pearl glossy synthetic paper of the present invention has a three-layer structure. The foamed intermediate layer is extruded in a twin screw main extruder with one side feeder. 39 to 95% by weight of a highly crystalline polypropylene having an isotacticity of 97% or more and 1 to 5% by weight of an antistatic agent are uniformly stirred by a hopper in front of the main extruder, and put into the main extruder. Further, 0 to 40% by weight of calcium carbonate powder and 0 to 20% by weight of titanium dioxide powder are weighed and then put into the main extruder by one or two side feeders. After uniformly kneading with the twin screw of the main extruder, the mixture of the resin and the inorganic powder is pushed into the intermediate runner of the T-die head. The paper layer is extruded by two twin screw main extruders having side feeders. 20 to 99.5% by weight of polypropylene, 0 to 12% by weight of polyethylene, 0 to 3% by weight of antistatic agent, 0.5 to 3% by weight of antiblocking agent, 0 to 2% by weight of ultraviolet absorber
Is uniformly stirred with a hopper in front of the sub-extruder, and then put into the sub-extruder. Further, 0 to 40% by weight of calcium carbonate powder and 0 to 20% by weight of titanium dioxide powder are weighed, and then put into a sub-extruder by one or two side feeders. After uniformly kneading with the twin screw of the auxiliary extruder, the mixture of the resin and the inorganic powder is pushed into both sides of the T-die head. The extrudates from the three extruders described above are combined and co-extruded with a T-die head to form a resin layer or paper-like layer / foamed intermediate layer / resin layer or paper-like sheet. Biaxial stretching,
Through the steps of corona treatment and winding, the thickness is 20 to 250
Produces micron double / single sided pearly glossy paper. The synthetic paper produced by the production method of the present invention is suitable for culture paper, and uses highly crystalline polypropylene as a main raw material. The polypropylene resin used in the present invention has a melt index (MFI) of 0.5 to 8 (230 ° C./2.16 kg A).
According to STM D1238), the polymer is mostly isotactic and homogeneous. In this type of polymer structure, the molecules are bonded to each other in the correct sequence. The uniformity of the mechanical strength and quality of the pearl glossy synthetic paper can be controlled by the molecular weight of the raw material and its distribution. The pearl glossy synthetic paper obtained by the production method of the present invention has a three-layer structure. As shown in FIG. 1, in order to enhance the paper imitation effect of the paper-like layer, polyethylene,
The inorganic powder is blended, and the glossiness, writing property, and printability can be adjusted by the amount of the inorganic powder. The MFI of polyethylene is 0.
1 to 7 are adopted. The strength of the paper-like surface can be adjusted by MFI of polyethylene. The inorganic powder used in the present invention can lower the density of the foamed intermediate layer (utilize the generation of micropores in the stretching step) and can provide the paper-like layer with excellent writing and printing properties different from plastic paper. . One or more inorganic powders are used by selecting one or more from the group of calcium carbonate, diatomaceous earth, clay, calcium oxide, barium sulfate, titanium dioxide and the like. Its particle size is 0.
It is between 1 and 10 microns and the dose is determined by the demand of the product. The invention is manufactured in a twin screw extruder that feeds the compound from the side. The inorganic powder is put into an extruder from a side feeder. The mixture can be uniformly kneaded with an extruder using a twin screw. In addition, the composite particles obtained by first kneading the inorganic powder and the resin can be put in the forefront hopper, mixed with various resins, and then put into an extruder. In the present invention, titanium dioxide powder is used to adjust the opacity, whiteness, and anti-ultraviolet property of the product. As the antistatic agent of the present invention, all the antistatic agents used in ordinary biaxially oriented polypropylene (BOPP) can be used. Tertiary amines are mainly used. Since tertiary amines have charge transfer properties, they can remove static electricity generated by processing friction. In the present invention, it is necessary to add an anti-adhesion agent because the synthetic papers stick to each other when they are wound up. Silica, clay, used in ordinary biaxially oriented polypropylene,
One type can be selected from polymethylacrylic acid methyl ester (PMMA), glass beads, and the like. The specific gravity of the polypropylene pearl glossy synthetic paper obtained in the present invention is 0.75 or less, and can be adjusted by the composition ratio of the mixture. This is equivalent to the synthetic paper of JP-A-3-87255.
As compared with 79, it is possible to manufacture a synthetic paper having a larger area with the same weight, and thus the economic efficiency is high. The biaxially stretched polypropylene pearl glossy synthetic paper obtained in the present invention has a three-layer structure of paper-like layer / foamed intermediate layer / paper-like layer or resin layer. There is a deep relationship. The usual biaxially stretched product of polypropylene film is
Most are clear products with no added filler. In the present invention, in order to imitate paper, it is necessary to add a large amount of an inorganic filler in the production process, and the problems concerning productivity, production capacity, and quality stability of the biaxial stretching production process must be overcome. FIG. 4 shows the apparatus and steps of the manufacturing process used for the polypropylene pearl glossy synthetic paper (25 to 250 microns) of the present invention. Extruder device ((1) in FIG. 4): One twin-screw main extruder with side feeders and two twin-screw sub-extruders with side feeders. The temperature setting conditions vary depending on the composition of the resin mixture, MFI, crystallinity, viscosity, production line speed, and product thickness,
Usually, the temperature is 180 to 280 ° C. If the temperature is lower than 180 ° C., plasticization of the resin does not proceed, and the resin cannot be extruded with a T-die head. Above 280 ° C., the resin is excessively plasticized and cracks occur. In the present invention, a three-layer synthetic paper (paper-like layer or resin layer / foamed intermediate layer / paper-like layer or resin layer) is manufactured by a three-layer coextrusion method. The extrudates of three layers are merged by the flow path design of the T-die head, and the three layers are co-extruded with the T-die head. Cooling roll device ((2) in FIG. 4): A water-cooled or gas-cooled cooling device. The three-layer coextruded molten coextrudate at 180-280 ° C is cooled and molded. The control of the cooling temperature has a great influence on whether the subsequent steps go smoothly. The cooling temperature is usually set at 15 to 60 ° C, and can be adjusted within this range by the thickness of the synthetic paper board and the speed of the production line. Longitudinal stretching device ((3) in FIG. 4): The paper sheet that has been subjected to cooling molding is placed in a longitudinal stretching device. First, heat to 115-150 ° C (choose according to the thickness of the paperboard and the speed of the production line) to soften the paperboard and stretch it in two steps, low speed and high speed.
Gives synthetic paper longitudinal strength. Also, it is formed by annealing. The stretching ratio in the machine direction is usually set to 3 to 6 times. Lateral stretching device ((4) in FIG. 4): The paper board thinned by the longitudinal stretching process is heated to 140 to 195 ° C. (select according to the thickness of the paper board and the speed of the production line) to be softened, It is stretched and further formed by annealing, and the size stability is enhanced by the partial shrinkage of the pearl synthetic paper. Usually, the transverse stretching ratio is set to 5 to 12 times. It can be selected according to the characteristics of the product. Corona treatment device ((5) in FIG. 4): Corona treatment is performed to improve the physical properties of the polypropylene pearl glossy synthetic paper, and processing such as printing, coating, and coating is facilitated. Corona treatment is performed with a high-frequency discharge device (adjusted according to the speed of the production line) with a treatment efficiency of 20 to 120 KW.
This results in a surface wet tension of 36-48 dynes / cm. Winding device ((6) in FIG. 4): The finished pearly glossy synthetic paper is wound up using an iron pipe to obtain a finished product having a width of 8 meters. If necessary, it is cut lengthwise or widthwise and packaged to obtain a roll or sheet product having a thickness of 25 to 250 microns. 25-250 thickness obtained by the production method of the present invention
Table 1 shows the thickness of the three layers of the micron biaxially stretched polypropylene pearl glossy synthetic paper. The thickness of the paper-like layer and the resin layer can be adjusted in the range of 1 to 30 microns.

To clearly explain the technical contents of the present invention,
Examples of the present invention in which synthetic papers for writing, printing, packaging and various uses are manufactured are shown below. However, the patent scope of the present invention is not limited to this. Example 1 Single-sided paper-like surface pearly glossy synthetic paper having a thickness of 250 microns or less After mixing 67% by weight of polypropylene (MFI: 2.4) and 3% by weight of an antistatic agent, a twin with a side feeder from a hopper. Put into a screw main extruder, and further add 20% by weight of calcium carbonate powder and titanium dioxide 1
After weighing out 0% by weight, they are fed into a twin screw main extruder, each with a feeder. Also, 62% by weight of polypropylene (MFI: 5) and polyethylene (MFI:
1) 12% by weight, 2% by weight of antistatic agent, 3 anti-sticking agents
% By weight and 1% by weight of an ultraviolet absorber were mixed by a mixer, and then put into a twin screw # 1 sub-extruder having a side feeder from a hopper. Further, after measuring 10% by weight of calcium carbonate powder and 10% by weight of titanium dioxide,
Twin screw # from two feeders each
Put into 2 extruders. Separately, polypropylene (MFI:
2.4) 97% by weight and 3% by weight of an antiblocking agent are mixed by a mixer, and then put into a twin screw # 2 sub-extruder having a side feeder from a hopper. The temperature of the extruder was set at 200 to 280 ° C, and T
Extrude from die head. Via a cooling roll set at 15 to 60 ° C., the polypropylene pearl glossy synthetic paper board is cooled and formed. The formed paper board is placed in a longitudinal stretching device, heated to 120 to 150 ° C., and then stretched 5 times in the longitudinal direction. After stretching, annealing is performed. After cooling, it is again placed in a transverse stretching device, heated to 150 to 185 ° C, and stretched 9 times in the transverse direction again. After stretching, annealing is performed to control the shrinkage of the synthetic paper. After exiting the transverse stretching device, put it in a corona treatment device to improve the printability of synthetic paper,
Finally, it is wound by a winding device. The single-sided paper-like surface pearl glossy synthetic paper having a thickness of 250 microns or less obtained by the above method,
It can be widely used for writing, printing, packaging and other uses. The thickness selected in this example is 60 microns, 100
Table 2 shows the physical properties of the single-sided paper-like surface pearly glossy synthetic paper of 120 μm and 120 μm. Example 2 Double-sided paper-like surface pearly glossy synthetic paper having a thickness of 250 microns or less After mixing 68% by weight of polypropylene (MFI: 2.4) and 2% by weight of an antistatic agent, a twin screw having a side feeder from a hopper. Put into the main extruder, further add 15% by weight of calcium carbonate powder and titanium dioxide 1
After weighing out 5% by weight, each is fed into the twin screw main extruder from two feeders. Further, 58% by weight of polypropylene (MFI: 5) and polyethylene (MFF)
I: 1) 12% by weight, 2% by weight of an antistatic agent, 3% by weight of an anti-blocking agent, and 1% by weight of an ultraviolet absorber were mixed by a mixer, and then twins having # 1 and # 2 side feeders from a hopper, respectively. Put in two screw sub-extruders. Further, after weighing 12% by weight of calcium carbonate powder and 12% by weight of titanium dioxide, they are fed into a # 1, # 2 twin screw sub-extruder from two side feeders, respectively. The temperature of the extruder is set at 200 to 280 ° C., and the extruder is extruded from a T-die head by a three-layer coextrusion method. 25-60
Via a cooling roll set to ° C., the polypropylene pearl glossy synthetic paper board is cooled and formed. The formed paper board is placed in a longitudinal stretching apparatus, heated to 120 to 150 ° C., and then stretched 4.5 times in the longitudinal direction. After stretching, annealing is performed. After cooling, it is put into the transverse stretching device again and 155
Heat to ~ 190 ° C and stretch again 8.5 times in the transverse direction. After stretching, annealing is performed to control the shrinkage of the synthetic paper. After exiting the transverse stretching device, it is put into a corona treatment device to improve the printability of the synthetic paper, and finally wound up by a winding device. The double-sided paper-like surface pearl glossy synthetic paper having a thickness of 250 μm or less obtained by the above method can be widely used for writing, printing, packaging and other uses. Table 3 shows the physical properties of the double-sided paper-like pearly glossy synthetic paper having a thickness of 60 microns, 100 microns, and 150 microns selected in this example. Example 3 Double-sided glossy pearly glossy synthetic paper having a thickness of 250 microns or less After mixing 62% by weight of polypropylene (MFI: 2.4) and 3% by weight of an antistatic agent, a twin screw main unit having a side feeder from a hopper Put into an extruder, and further add 20% by weight of calcium carbonate powder and titanium dioxide 1
After weighing out 5% by weight, each is fed into the twin screw main extruder from two feeders. Also, after mixing 96% by weight of polypropylene (MFI: 3.0), 2% by weight of an antistatic agent and 2% by weight of an anti-adhesive agent by a mixer, a twin / # 2 side feeder having # 1 and # 2 side feeders, respectively.
Put in screw co-extruder. Extruder temperature 200 ~
The temperature is set to 280 ° C., and extruded from the T-die head by a three-layer coextrusion method. Via a cooling roll set at 15 to 60 ° C., the polypropylene pearl glossy synthetic paper board is cooled and formed. The formed paper board is placed in a longitudinal stretching device, and the
After heating to ~ 150 ° C, the film is stretched 5 times in the machine direction. After stretching, annealing is performed. After cooling, it is again placed in a transverse stretching apparatus, heated to 150 to 185 ° C.,
Perform double stretching. After stretching, annealing is performed to control the shrinkage of the synthetic paper. After exiting the transverse stretching device, it is put into a corona treatment device to improve the printability of the synthetic paper, and finally wound up by a winding device. The double-sided glossy pearly glossy synthetic paper having a thickness of 250 microns or less obtained by the above method is written, printed,
Can be widely used for packaging and other uses. The thickness selected in this example is 70 microns, 110 microns, 1
Table 4 shows the physical properties of a 40-micron double-sided glossy pearly glossy synthetic paper.

[0008]

The synthetic paper obtained by the production method of the present invention is
A conventional product in which a paper-like layer is stretched in the longitudinal direction, but a film that has not been stretched in the transverse direction, is used as a uniaxially stretched layer.
There is a great difference in the composition of the raw materials used. This allows
It can replace natural paper and expand its applications, and has the following advantages. The raw material of the paper-like layer is mainly composed of polypropylene, polyethylene, titanium dioxide, and inorganic powder, has a mad luster, and has higher whiteness and shielding degree than conventional paper. The biaxially stretched paper-like layer has excellent rigidity and good fixability of the inorganic powder, and the powder does not fall off during the printing process.
Since the paper-like layer, the resin layer, and the foamed intermediate layer have the same stretching ratio and the paper shrinks uniformly, the heated surface is unlikely to be deformed into a wave shape. Further, the paper-like layer and the foamed intermediate layer having the same stretching ratio are not easily separated. The thickness of the paper-like layer and the resin layer is 1 to 30
It can be controlled in the micron range by the output from the co-extruder (the thickness of the product can be varied according to demand and application). The production speed of the manufacturing process is fast, reaching up to 3.5 tons / hour. The maximum width is 8 meters and the thickness is 25-250 microns, giving you a wide choice. Paper-like layer,
The resin layer and the foamed intermediate layer are extruded from a twin screw extruder having a feeder on the side surface, and since the kneading of the raw materials is uniform, the thickness of the product can be controlled within ± 2%. Since the extruder can put the powdered inorganic powder into the side feeder, it is not necessary to use only composite particles (master batch) of the inorganic powder, and the raw material cost can be greatly reduced. In addition, composite grains of inorganic powder can be produced by a single screw extruder. However, it is necessary to increase the L / D ratio (length / diameter) of the threaded rod of the extruder to make the kneading of the raw materials uniform. Low production cost and market competitiveness.

[Brief description of the drawings]

FIG. 1 shows a three-layer structure of a biaxially stretched polypropylene pearl glossy synthetic paper having a thickness of 25 to 250 μm obtained by a three-layer coextrusion method (paper layer / foamed intermediate layer / paper layer).

FIG. 2 shows a three-layer structure of a biaxially stretched polypropylene pearl glossy synthetic paper having a thickness of 25 to 250 μm obtained by a three-layer coextrusion method (paper-like layer / foaming intermediate layer / resin layer).

FIG. 3 shows a three-layer structure of a biaxially stretched polypropylene pearl glossy synthetic paper having a thickness of 25 to 250 μm obtained by a three-layer coextrusion method (resin layer / foaming intermediate layer / resin layer).

FIG. 4 is an explanatory view of a manufacturing apparatus according to the present invention.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

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Claims (1)

[Claims] A thickness of 25 to 25 obtained by a three-layer coextrusion method.
In a method for producing a 0-micron biaxially oriented polypropylene (BOPP) pearl glossy synthetic paper, an isotacticity of 9
Highly crystalline polypropylene of 7% or more (MFI: 0.5 to
8) 39-95% by weight and calcium carbonate powder 0-40
Weight%, titanium dioxide 0-20 weight%, antistatic agent 1
-5% by weight of a polypropylene resin mixture, and 22-99.5% by weight of polypropylene and 0% of a polyethylene resin.
-12% by weight, titanium dioxide powder 0-20% by weight, calcium carbonate powder 0-40% by weight, antistatic agent 0
A resin mixture consisting of 3% by weight, 0.5 to 3% by weight of an antiblocking agent, and 0 to 2% by weight of an ultraviolet absorber was mixed with one twin screw main extruder having a side feeder and a twin The screw sub-extruder was put in from two hoppers and feeders, the extruder temperature was set to 180 to 280 ° C, and after merging, it was extruded from a T-die head to form a pearl glossy synthetic paper sheet,
After cooling and forming with a cooling roll at 60 ° C., and then biaxially stretching the paper sheet, the sheet is heated to 150 to 150 ° C., and then stretched.
Annealing, stretching 3 to 6 times in the machine direction, further heating to 140 to 195 ° C, stretching, annealing, stretching in the transverse direction 5 to 12 times, and then 20 to 120 KW
Efficient high-frequency corona treatment, winding by winding device,
Three types of three layers: a paper layer having a thickness of 25 to 250 microns / foaming intermediate layer / the paper layer, the paper layer / the foaming intermediate layer / the resin layer, the resin layer / the foaming intermediate layer / the resin layer. Co-extruded polypropylene pearl glossy synthetic paper and coated paper of coating synthetic paper, characterized in that the thickness obtained by the three-layer co-extrusion method is 2
A method for producing 5-250 micron biaxially oriented polypropylene pearl glossy synthetic paper.