JPH089195B2 - Synthetic resin bag material manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mass-market store such as a supermarket, and other items such as clothing, bags, books, shoes, toys and everyday foods, which are used as a handbag for accommodating the purchased items. TECHNICAL FIELD The present invention relates to a method for manufacturing a bag material of a synthetic resin bag for use in a car.

[0002]

2. Description of the Related Art Heretofore, a bag for accommodating a purchased product as described above has been made of, for example, low-density polyethylene, and its manufacturing method is to extrude a melt of low-density polyethylene through a gap between dies of an appropriate size. The formed film is cut and welded to an appropriate length, and then a handle is provided on the top and a fold is provided on the bottom to form a bag.

[0003]

However, since the film of the above-mentioned low-density polyethylene bag is made to have a constant thickness, it is inevitable that the portion for storing the article and the portion for the handle have the same thickness. Absent.

However, when comparing the storage portion and the handle portion for suspending the storage portion, when the article is stored, the weight of the storage portion causes the handle portion to be weaker due to the presence of a hole for the handle and the like. There is a high possibility of breaking.

Therefore, in order to make the handle strong, it is inevitable that the bag itself having a large thickness must be used, and the storage portion becomes thicker than necessary.

[0006] This increase in thickness increases the weight and volume of each sheet, which in turn increases the cost per bag.
There is a drawback that it is difficult to handle because it is thick.

For this reason, as shown in an example in FIG. 8, there has been considered a method of integrally forming the tubular film c by thickening the portion b where the handle hole a is provided and thinning the other portions. In this method, when a die having an appropriate gap is fitted in the die body and the melt is extruded from the gap to form a tubular film, the die is preliminarily processed so that the peripheral portion has a large gap.

On the other hand, low-density polyethylene has the property of becoming thicker when the amount of the melt coming out from the gap between the die body and the die mandrel increases, and conversely, when the amount of high-density polyethylene is large, it becomes thin. In any case, in the above-mentioned conventional manufacturing method, since the thick portion is formed depending on the gap size of the die, the die is specialized and in order to obtain a desired thick wall, various different types are required. You need a die,
It was a problem in terms of cost.

In view of this, the present invention provides a tubular film, which is a raw material for a synthetic resin bag, in which the storage portion is thin as in the conventional case and only the portion where the handle is provided is thick, without the need for many steps and a die. It is an object of the present invention to provide a manufacturing method capable of rapidly manufacturing by adjusting a desired uneven thickness by utilizing a temperature difference of a melt with one die without dedicating the above.

[0010]

To achieve the above object, in the present invention, a bag resin material (for example, polyethylene) is provided in a gap between a die body forming an inflation die and a die mandrel installed in the die body. In the process of making a cylindrical film by injecting the above, the heating part around the die mandrel is divided into a high temperature region and a low temperature region by a plurality of heating means embedded in the outer periphery of the die, and the upper surface of the die body is located near the top surface. A cooling ring that blows cooling air around the entire circumference of the tubular film is provided at the position,
The gap of the cooling ring in the range corresponding to the low temperature region is made larger than the other regions to increase the amount of air blown out, and the cooling air jetted from this cooling ring is directed to the outer peripheral surface of the tubular film by an air guide. Flowing in an ascending direction along the outer peripheral surface of the tubular film, and at the same time as cooling the entire tubular film, forming a thicker portion of the film that comes out of the low temperature region and a thinner portion of the film that comes out of the high temperature region. Is characterized by.

[0011]

With this configuration, when a tubular resin film is made by injecting a resin material for bag (for example, polyethylene) from below into the gap between the die body of the inflation die and the die mandrel, it is embedded in the outer periphery of the upper die near the injection port on the upper surface The heating portion around the die mandrel is divided into a high temperature region and a low temperature region by the heating means, and the high temperature region is heated at a high temperature and the low temperature region is heated at a lower temperature.
As a result, the material melt in the high temperature region is quickly extruded from the die to form a thin film, while the material melt in the low temperature region is partially supercooled by the cooling means to cool early when extruding from the die. As a result, it becomes easier to harden and a partially thick tubular film is formed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings.

1 and 2 are a sectional view and a plan view of the inflation die 1, in which a die mandrel 3 is fitted inside a cylinder of an outer cylinder-shaped die body 2 with an appropriate gap 4.

The die mandrel 3 is provided with a plurality of spiral grooves 5 up to a predetermined height in order to reduce pressure loss inside the die mandrel 3, and the upper portion of the spiral groove 5 is formed on the die body 2. It is formed without a groove so as to have a proper gap 8 between the adjustment ring 6 provided on the upper part and the die land 7.

The bottom portion 9 of the die mandrel 3 is formed to have the same diameter as the outer diameter of the die body 2 and is fixed to the die body 2 by tightening means (not shown) such as bolts.

A resin inlet 10 is provided at the center of the bottom surface of the bottom portion 9.
The resin that has flowed into the spiral groove 5 of the die mandrel 3 from here rises in the gap 4 between the die body 2 and reaches the gap 8 between the upper die land 7 and the die mandrel 3 and from there It is designed to be released as a film.

In the lower part of the die body 2, the blow-out port 1 on the upper surface is passed from the outside through the center 11 of the die mandrel 3.
An expansion air introduction pipe 13 communicating with up to 2 is provided.

Further, a plurality of band heaters 14 are vertically provided on the outer periphery of the die body 2, and thermocouples 15 and the like are provided at appropriate positions between the band heaters 14, both of which are inside the die 1. It prevents the resin solution from flowing into the coagulation.

A recess 16 is formed at the lower end of the die land 7 together with the corresponding die mandrel 3 side, and the recess 16 extends to the upper portion of the die body 2.

The opposing ends of the adjusting ring 6 and the die body 2 are formed to have a smaller diameter than the outer diameter and to have inner and outer diameters in the circumferential direction so that the adjusting ring 6 side is fitted on the die body 2 side. It is provided in.

The adjusting ring 6 is for adjusting the uneven thickness at the time of processing in the gap 8 with the upper part of the die mandrel 3, and has an appropriate gap 17 between itself and the die body 12 to form an outer side. Is attached by a plurality of uneven thickness adjusting bolts 18.

Therefore, the uneven thickness is adjusted by adjusting the uneven thickness adjusting bolt 18 for the gap 17.

In the adjusting ring 6, a plurality of upper and lower thermocouples 19a and a cartridge heater 19b (or a partially notched band heater) serving as heating means are radially embedded from the outside toward the inside. Has been done. It is desirable that this position be buried as close to the recess 16 as possible.

The number of buried parts may be 4, 6, 8 or 10 depending on the size of the die, but if they are too close, it becomes difficult to control the temperature of each section.

In the present invention, in order to more easily form the thick portion to be obtained, the resin discharged from the die is partially cooled from the side surface by a cooling means such as a blower. When extruding, the cooled part is made thicker, for example, as shown in FIG.
By partially supercooling only the points “4” and “5” of the other part than the other part, the bag material extruded from this part can be easily made thick. For this cooling, if possible, it is desirable to control the cooling to be ON or OFF.

As a concrete example of the above cooling, FIG.
As shown in FIG. 6, an air passage 21 flowing from the side surface of the die 1 is provided on the upper surface of the die 1 so that a cooling ring 20 as a cooling means is formed by cooling air. In the figure, 22 is a cooling cover, 23 is an air guide, and 8 is a gap between the adjusting ring 6 and the die mandrel 3 described above.
As an example of the cooling effect, as shown in FIG. 7, when the cooling ring 20 shown in FIGS. 5 and 6 is used and the gap of the cooling ring is widened in the range of ⅛, the effect is still improved by 50%. can get.

That is, when the cooling ring is 150φ In the case of 140φ, it may be 54 m / m. In the above embodiment, the gap 24 is provided on one side, but it may be provided on both sides.

In any case, if the gap 24 is large, the air volume becomes large and the degree of cooling becomes high. Next, the operation will be described.

First, in the case of manufacturing a general cylindrical film of uniform thickness without uneven thickness, when the melt is poured into the inflation die 1 through the resin inlet 10, the melt enters the spiral groove 5.

Then, it is heated by the band heater 14 and the thermocouple 15, rises in the spiral groove 5, passes through the concave portion 16, and is passed through the gap 8 between the die land 7 and the die mandrel 3 to the die 1.
Although it is extruded to the outside, it is expanded by the air blown from the blowout port 12 of the air constantly sent from the inflating air introducing pipe 13, and becomes a tubular film to form a bag material having a uniform thickness.

If the bag material thus formed has an uneven thickness, the adjusting bolt 18 is adjusted to prevent the uneven thickness.

FIG. 3 shows an embodiment in which twelve places around the die mandrel 3 are heated using a cartridge heater 19a and a thermocouple 19b which are examples of heating means. In this case, 12 points are provided on the periphery, and the points are divided into a high temperature region A and a low temperature region B, and are divided into "4" and "5".
Point is 170 ° C., points “3” and “6” are two-stage low temperature regions B of 200 ° C., and “1” to “2” and “7” to “1”.
Heating is performed by providing two regions having a temperature difference, which is a high temperature region A in which all the points “2” are 240 ° C.

In this way, the film extruded from the gap in the high temperature region A is thin, and the film extruded from the gap in the low temperature region B is thick. At this time, the die in the low temperature area B is partially supercooled from the side surface by a cooling means such as a blower, so that the cooled portion is made thick at the time of extrusion, and “4” and “4” in FIG. By partially supercooling only the point "5" than the other part, the bag material extruded from this part can be made thicker.

That is, as seen in the cross section of the tubular film, as shown in FIG. 9, the region B is made thick by the primary thickening due to the temperature difference of the die body 2, and then the region C is made by the cooling air. A second thickening is performed by supercooling, whereby a part of the same tubular film is manufactured as a thick film.

In this embodiment, the production of a single-layer film was described with one resin inlet 10 as shown in FIG. 4, but as shown in FIG. 4, two layers of high density polyethylene on the inside and medium or low density polyethylene on the outside are used. In this case, the inner layer portion 25 is from the lower opening 26, and the outer layer portion 27 is from the side opening 28 (this side opening 28 may be provided at the bottom portion as shown by the dotted line in FIG. 4).
It is possible to manufacture a two-kind two-layer bag material having different wall thicknesses as in the case of one layer by inflowing the same from above and making a difference in heating temperature as shown in FIG.

Similarly, in the case of 2 layers 3 layers, 3 layers 3 layers, 3 layers 5 layers, 5 layers 5 layers, etc., a multilayer film can be prepared by providing a large number of resin inlets.

In the case of FIG. 4, structurally the same parts as those of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

[0038]

As described above, according to the present invention, the bag material can be manufactured in the same process as that of the conventional one, and moreover, various kinds of dedicated die mandrels due to the difference in wall thickness are required for manufacturing. Without using a single type of mandrel, it is possible to adjust the difference in wall thickness, the difference in parts, etc. by supercooling with high temperature heat difference and cooling means, and provide the bag material desired by users at low cost. can do. In particular, the present invention uses the difference in the gap of the cooling ring that blows the cooling air around the entire circumference of the tubular film immediately after leaving the die after performing the primary thickening due to the temperature difference of the die. At the same time as cooling the other portion of the tubular film, the secondary thickening is performed by supercooling, and the cooling air is cooled while rising along the outer peripheral surface of the tubular film to cool the desired thick portion. Since it is formed, the tubular film formed by the die is not deformed so as to bulge to the thin side, and a product having a uniform inner diameter can be reliably manufactured.

Further, it is possible to carry out any uneven thickness processing by controlling the temperature and the processing method of the cooling ring, and it is possible to easily and quickly manufacture a product having a desired partial wall thickness.

[Brief description of drawings]

FIG. 1 is a sectional view showing a die portion for carrying out the method of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a plan view showing a heated state of a melt applied to the method of the present invention.

FIG. 4 is a cross-sectional view of a die portion when manufacturing a multilayer material.

FIG. 5 is a plan view showing an example of a cooling unit according to the present invention.

FIG. 6 is a sectional view of the same.

FIG. 7 is an explanatory diagram of a single cooling ring.

FIG. 8 is an explanatory view showing an example of molding a bag.

FIG. 9 is an explanatory view showing a molding state of a thick portion of the film.

[Explanation of symbols]

 1 Inflation Die 2 Die Main Body 3 Die Mandrel 4 Gap 5 Spiral Groove 6 Adjustment Ring 7 Die Land 8 Gap 9 Bottom 10 Resin Inlet 12 Outlet 13 Air Inlet Pipe 14 Band Heater 15 Thermocouple 16 Recess 17 Gap 18 Eccentricity Adjusting Bolt 19a Thermocouple 19b Cartridge heater 20 Cooling ring 21 Air passage 22 Cooling cover 23 Air guide 24 Gap 26 Lower port 28 Side port

Continuation of the front page (31) Priority claim number Sho 62-145299 (32) Priority date Sho 62 (1987) June 12 (33) Country of priority claim Japan (JP) (31) Priority claim number Special Japanese Patent Application No. Sho 62-154499 (32) Priority Date Sho 62 (1987) June 23 (33) Priority Claiming Country Japan (JP) (56) Reference JP-A-56-164824 (JP, A) JP-A-54 -92474 (JP, A) Actual development Sho 58-3220 (JP, U) Japanese Patent Sho 49-31542 (JP, B1)

Claims (1)

[Claims] 1. In a process of making a tubular film by injecting a resin material for a bag into a gap between a die body forming an inflation die and a die mandrel installed in the die body, a plurality of pieces embedded in the outer periphery of the die upper part are formed. The heating ring around the die mandrel is divided into a high temperature region and a low temperature region by the heating means and a cooling ring that blows cooling air around the entire circumference of the tubular film at a position near the upper surface of the die body. Is provided, the gap of the cooling ring in the range corresponding to the low temperature region is made larger than the other regions to increase the blowing amount of air, and the cooling air jetted from this cooling ring is directed to the outer peripheral surface of the tubular film. It is made to flow in an ascending direction along the outer peripheral surface of the tubular film by an air guide, and at the same time when the entire tubular film is cooled, the thick portion of the film coming out of the low temperature region is removed. The thick-walled al, manufacturing method of the bag material of the synthetic resin bag and forming a film emanating from the high temperature region in the thin.