JPH07333B2 - Method and apparatus for producing thermoplastic resin sheet - Google Patents

Description

The present invention relates to a method and an apparatus for producing a thermoplastic resin sheet used as a support for a photographic film such as an X-ray film.

[Background of technology]

For example, a thermoplastic resin sheet used as a support for a photographic film such as an X-ray film is usually manufactured by drying a thermoplastic resin chip, extrusion-molding it, and then biaxially stretching it.

As a chip of the thermoplastic resin, a powder of a small piece having a square shape of several mm or a cylindrical shape of several mm is usually used.

However, in the production of a thermoplastic resin sheet, usually, sheet waste is generated after extrusion molding or after biaxial stretching, that is, after vertical axis stretching and horizontal axis stretching. If the sheet scraps generated from such a manufacturing process can be reused, the yield is high and the thermoplastic resin sheet can be economically manufactured.

In addition, in order to obtain a thermoplastic resin sheet with uniform characteristics, it is necessary to keep the mixing ratio of recycled chips and thermoplastic resin chips, which is obtained by collecting sheet waste generated from the manufacturing process, constant. To be done. This is because the recycled chips already have the experience of being heated during extrusion molding, so the physical properties, such as the intrinsic viscosity during melting, are slightly different from those of the newly used thermoplastic resin chips, so the mixing ratio is constant. This is because a thermoplastic resin sheet having uniform properties cannot be obtained unless the above is adopted. Further, in the case of producing a colored thermoplastic resin sheet, since the reused chip has a specified concentration, the mixing ratio of the reused chip and the thermoplastic resin chip is to prevent coloring unevenness. Must be constant.

[Problems to be solved by the invention]

From this point of view, when the recycled chips are added to the new thermoplastic resin chips, it is necessary to weigh each before mixing them. In the process of manufacturing the thermoplastic resin sheet, it is economical to supply the raw material in a flow that is particularly adapted to the capacity of the extrusion molding mechanism.

However, when the extrusion mechanism has a large capacity,
Since the amount of thermoplastic resin chips and recycled chips to be weighed in the weighing process is correspondingly large, a considerable amount of time is required for this weighing, and accordingly, waiting time is increased in the next step of drying, which results in the production. There is a problem that the process cannot be efficiently performed and energy for heating is wastefully consumed in the extrusion molding process at the start.

[Object of the Invention]

The present invention has been made based on the above circumstances, and an object thereof is to measure raw materials with high accuracy and to quickly measure the raw materials without waiting time in each manufacturing process. It is an object of the present invention to provide a manufacturing method and a device capable of efficiently supplying a thermoplastic resin sheet having uniform characteristics to the above.

[Means for solving problems]

The method for producing a thermoplastic resin sheet of the present invention, after drying a mixture of thermoplastic resin chips and recycled chips obtained by collecting sheet waste generated from the manufacturing process,
The step of extruding and then biaxially stretching is performed, and the thermoplastic resin chips and the reusable chips are weighed so as to have a certain ratio, and then supplied and stored in a common intermediate storage tank. From the thermoplastic resin chips and recycled chips are supplied to the subsequent manufacturing process including the drying process from
The thermoplastic resin chips and the recycled chips to be next supplied to the intermediate storage tank are weighed while the thermoplastic resin chips and the recycled chips are stored in the intermediate storage tank. And

Further, the manufacturing apparatus of the present invention, after drying the mixture of the chips of the thermoplastic resin and the reusable chips obtained by collecting the sheet waste generated from the manufacturing process, extruded, then biaxially stretched and heat-treated. An apparatus for producing a sheet made of a thermoplastic resin, comprising: a reservoir for the chips of the thermoplastic resin, a first measuring mechanism for measuring the amount of chips of the thermoplastic resin supplied from the reservoir, a reservoir for the reused chips, and A second weighing mechanism that measures the amount of recycled chips supplied from this storage tank, an intermediate storage tank, chips of the thermoplastic resin that are weighed by the first weighing mechanism, and a recycle weight that is weighed by the second weighing mechanism. A transport mechanism for transporting the used chips to the intermediate storage tank, and a supply mechanism for supplying the chips of the thermoplastic resin and the reused chips from the intermediate storage tank to subsequent steps including a drying step, While the thermoplastic resin chips and the recycled chips are stored in the intermediate storage tank, the thermoplastic resin chips to be next supplied to the intermediate storage tank by the first measuring mechanism and the second measuring mechanism. And controlling each of the reusable chips to be weighed. According to such a method, the chips of the thermoplastic resin and the reusable chips are not supplied to the subsequent steps immediately after being weighed, but they are once stored in the intermediate storage tank, so that this intermediate storage tank functions as a buffer. Therefore, the weighed thermoplastic resin chips and the reusable chips can be rapidly supplied to the subsequent process without waiting time, and the already weighed thermoplastic resin chips and the reusable chips can be supplied. While each is stored in the intermediate storage tank, each of the thermoplastic resin chips and the recycled chips to be supplied next is measured,
This metering and the supply of thermoplastic resin chips and recycled chips from the intermediate storage tank to the subsequent process can be carried out in parallel, so that even if the quantity to be measured is large, it follows the intermediate storage tank. Without interrupting the manufacturing process, sufficient time can be taken for the weighing, and weighing can be performed with high accuracy. As a result, a thermoplastic resin sheet with uniform characteristics can be manufactured with high efficiency. be able to.

Further, according to the manufacturing apparatus of the present invention, an intermediate storage tank for storing the amount of the thermoplastic resin chips weighed by the first weighing mechanism and the amount of recycled chips weighed by the second weighing mechanism is provided. The thermoplastic to be supplied to the intermediate storage tank by the first and second weighing mechanisms while the thermoplastic resin chips and the recycled chips that have been weighed prior to the intermediate storage tank are stored. Since the resin chips and the reusable chips are controlled so as to be weighed individually, for example, by using an intermediate storage tank having a capacity larger than that of the extrusion molding mechanism, the extrusion molding mechanism can be efficiently used. It is possible to manufacture a thermoplastic resin sheet having uniform properties while operating at a high production rate with a high production rate, and it is possible to obtain a production apparatus suitable for mass production in particular.

Hereinafter, the present invention will be described in detail.

In the manufacturing method of the present invention, the weighed thermoplastic resin chips and the reusable chips weighed at a fixed ratio with the chips are first stored in a common intermediate storage tank.

Then, the thermoplastic resin chips and the reused chips stored in the intermediate storage tank are subjected to a subsequent step, for example, a drying step to be dried, and then, if necessary, subjected to a mixing step to mix the both, and after dry mixing The thermoplastic resin chips and reusable chips are subjected to an extrusion molding step to be extruded, and then biaxially stretched, that is, longitudinally stretched and transversely stretched, thereby producing a thermoplastic resin sheet.

During this period, for example, when the supply of the measured amount of the thermoplastic resin chips and the reused chips to the intermediate storage tank is finished, the measurement of the next thermoplastic resin chips and the recycled chips is immediately started. Therefore, the weighing of the thermoplastic resin chips and the recycled chips is performed while the preceding thermoplastic resin chips and the recycled chips are stored, and the heat to be supplied next is obtained. In parallel with the weighing of the plastic resin chips and the recycled chips, the supply of the thermoplastic resin chips and the recycled chips to the subsequent process can be carried out from the intermediate reservoir.
When the thermoplastic resin chips and reused chips stored in the intermediate storage tank are supplied to the subsequent process and become empty, promptly weigh a quantity of the thermoplastic resin chips and reused chips into the intermediate storage tank. Supply to and store here.

For example, when performing the manufacturing process in a batch system, it is necessary to measure thermoplastic resin chips and recycled chips in an amount corresponding to one batch, so that the capacity of the intermediate storage tank is one batch. It is preferable to use an amount slightly larger than the amount corresponding to the amount. By doing this, during the drying period of the thermoplastic resin chips and the reused chips, it is necessary to take sufficient time to weigh the thermoplastic resin chips and the sheet waste pulverized product required for one batch, respectively. Therefore, the weighing accuracy can be improved. Then, after the drying is completed and the dried thermoplastic resin chips and the reused chips are subjected to the extrusion molding process, immediately one batch of the thermoplastic resin chips and the reused chips stored in the intermediate storage tank are obtained. Can be attached to the subsequent step by means of, for example, pneumatic transportation, so that it is possible to perform the rapid step without waiting time in the subsequent step.

As reusable chips, sheet scraps generated from the manufacturing process, that is, sheet scraps generated after extrusion molding or after vertical axis stretching and horizontal axis stretching, are collected, crushed, and further classified by a screen or the like as necessary. It is possible to use a pulverized product of about several mm obtained in this way, or a so-called granulated product, which is obtained by pulverizing the collected sheet scraps and then further semi-melting and processing into a size of about several mm.

As the thermoplastic resin chip, for example, a powder of a few mm square or a few mm cylindrical small piece is used, and as the thermoplastic resin, generally a polyester resin or the like can be preferably used. It is not limited to. Particularly suitable polyester resins are those in which the acid component is mainly terephthalic acid and the alcohol component is mainly ethylene glycol, but other acid components and / or
Alternatively, it may contain an alcohol component. Examples of such other acid component include isophthalic acid, one or more of naphthalenedicarboxylic acid, β-hydroxyethoxybenzoic acid, p-hydroxybenzoic acid, adipic acid, sebacic acid, and the like. Other alcohol components include trimethylene glycol, tetramethylene glycol, hexamethylene glycol, 1,4
Examples thereof include one or more fatty acid or alicyclic or aromatic dioxy compounds such as cyclohexanedimethanol, and polyalkylene glycols such as polyethylene glycol. Preferred polyester resins have at least 80 mol% of repeating structural units
Is an ethylene terephthalate unit.

By using such a polyester resin, a tough thin sheet can be easily produced, but on the other hand, hydrolysis is likely to occur, and therefore it is important to sufficiently dry the sheet in the drying step.

According to the above manufacturing method, the thermoplastic resin chips and the reused chips are once stored in the intermediate storage tank instead of being immediately subjected to the subsequent steps after being weighed, so that the intermediate storage tank functions as a buffer. Therefore, the weighed thermoplastic resin chips and the reusable chips can be rapidly supplied to the subsequent process without waiting time, and the already weighed thermoplastic resin chips and the reusable chips can be obtained. Since the next thermoplastic resin chip and recycled chip are weighed in the state of being stored in the intermediate storage tank, this measurement and supply of the thermoplastic resin chip and recycled chip from the intermediate storage tank to the subsequent process are performed. Can be carried out in parallel, thus allowing sufficient time for the weighing without interrupting the subsequent steps. Thus the amount to be metered is able to perform weighing with high accuracy even in a large amount, a uniform thermoplastic resin sheet of this result characteristics can this be produced with high efficiency.

FIG. 1 is an explanatory view showing the outline of an example of the manufacturing apparatus of the present invention. 1 is a tank for storing thermoplastic resin chips, 2 is a weighing mechanism for weighing thermoplastic resin chips (first weighing mechanism),
3 is a storage tank for reused chips, 4 is a measuring mechanism for measuring reused chips (second measuring mechanism), 5 is a chip storage tank for storing the measured amount of thermoplastic resin chips and reused chips together , 6 is a drying mechanism, 7 is a mixing mechanism, 8 is an extrusion molding mechanism, 9 is a vertical axis stretching mechanism, 10 is a horizontal axis stretching mechanism,
11 is a transport mechanism, 12 is a supply mechanism, and 13, 14 and 15 are crushing and classifying mechanisms for crushing and classifying sheet scraps to be formed after extrusion molding, vertical axis stretching, and horizontal axis stretching to obtain reused chips. is there.

By configuring the intermediate storage tank 5 to have a capacity larger than the capacity of the extrusion molding mechanism 8, for example, it becomes possible to mass-produce thermoplastic resin sheets in high efficiency.

In the measuring mechanisms 2 and 4, the thermoplastic resin chips and the reusable chips in an amount corresponding to, for example, one batch are weighed, and the measured amount of the thermoplastic resin chips and the reusable chips are, for example, air. First, it is transported to the intermediate storage tank 5 by the transportation mechanism 11 including transportation means and is temporarily stored therein.

Immediately after the weighed thermoplastic resin chips and the reused chips have been transported to the intermediate storage tank 5 in this manner, the amount of the thermoplastic resin chips and the amount of the thermoplastic resin chips corresponding to the next one batch in the weighing mechanisms 2 and 4 Weighing of recycled chips is started. Therefore, the weighing of the thermoplastic resin chips and the recycled chips is performed while the preceding thermoplastic resin chips and the recycled chips are stored, and the heat to be supplied next is obtained. In parallel with the weighing of the plastic resin chips and the recycled chips, the supply of the thermoplastic resin chips and the recycled chips to the subsequent process can be carried out from the intermediate reservoir. When the thermoplastic resin chips and the reuse chips in the intermediate storage tank 5 are supplied to the subsequent drying mechanism 6 by the supply mechanism 12, the measured thermoplastic resin chips and the reuse chips are immediately emptied by the transport mechanism 11. It is transported to the intermediate storage tank 5 which has been stored, is temporarily stored there, and the same operation is repeated thereafter.

In the drying mechanism 6, chips of the thermoplastic resin and recycled chips are supplied from the intermediate storage tank 5 in an amount corresponding to one batch, and these chips are dried.

The dried thermoplastic resin chips and reused chips are then supplied to a mixing mechanism 7, where they are sufficiently mixed and then supplied to an extrusion molding mechanism 8 where they are extruded while being heated and melted. Then, the vertical axis stretching mechanism 9 performs vertical axis stretching, and the horizontal axis stretching mechanism 10 performs horizontal axis stretching, whereby a thermoplastic resin sheet having a thickness of about 75 to 175 μm is usually obtained.

During the execution of the manufacturing process, the sheet waste generated after the extrusion molding is crushed and classified by the crushing and classifying mechanism 13 to be reused chips and then transported to the storage tank 3, and the sheet waste generated after the vertical axis stretching is crushing and classifying mechanism. After being crushed and classified by 14 and reused chips are transported to the storage tank 3, the sheet waste generated after the horizontal axis stretching is crushed and classified by the crushing and classification mechanism 15 to be reused chips and then stored in the storage tank 3. They are transported and reused.

According to the above manufacturing apparatus, the intermediate storage tank 5 for storing together the thermoplastic resin chips and the reused chips measured by the measuring mechanisms 2 and 4 is provided, and the thermoplastic resin chips are stored in the intermediate storage tank 5. While the reusable chips are stored, the weighing mechanisms 2 and 4 are controlled so that the thermoplastic resin chips and the reusable chips to be next supplied are weighed. By using, for example, a capacity larger than that of the extrusion molding mechanism 8 as the intermediate storage tank 5, a thermoplastic resin sheet having uniform characteristics can be manufactured at a high production rate while operating the extrusion molding mechanism 8 efficiently. It is possible to obtain a manufacturing apparatus suitable for mass production.

The above description is based on an example of the manufacturing apparatus, but various embodiments are possible in the present invention.

For example, when it is used as a support for an X-ray film or the like, a thermoplastic resin sheet colored with, for example, blue dye fine powder may be required in order to make the image easy to see during diagnosis by the X-ray film. In the case of an apparatus capable of producing such a colored thermoplastic resin sheet, the apparatus is configured by further adding necessary components such as a dye fine powder storage tank. Such dye fine powder usually has an average particle size of 15
A fine powder of about 30 μm is used. In the case of obtaining a colored thermoplastic resin sheet, the coloring concentration is not necessarily limited to an appropriate value as necessary in relation to the application, but is generally 200 to 200 in a colored thermoplastic resin sheet. It is preferable to select the content ratio of the dye fine powder so as to be an appropriate value within the range of 300 ppm (weight). As the dye fine powder, generally, anthraquinone dye fine powder can be used, but the dye fine powder is not limited thereto.

[Effects of the Invention] As described above, according to the method for producing a thermoplastic resin sheet of the present invention, the thermoplastic resin chips and the reused chips are not immediately subjected to the subsequent step immediately after being weighed. Once stored in the intermediate storage tank, this intermediate storage tank functions as if it were a buffer, so that the weighed thermoplastic resin chips and recycled chips can be quickly supplied to the subsequent process without waiting time. As long as the thermoplastic resin chips and the recycled chips that have already been weighed are stored in the intermediate storage tank, each of the thermoplastic resin chips and the recycled chips to be supplied next is measured. This metering and the feeding of thermoplastic chips and recycled chips from the intermediate storage tank to the subsequent process can be carried out in parallel, and Even if there is a large amount of power, it is possible to take sufficient time for the relevant weighing without interrupting the manufacturing process subsequent to the intermediate storage tank and to perform the weighing with high accuracy. It is possible to manufacture a thermoplastic resin sheet having a uniform structure with high efficiency.

Further, according to the manufacturing apparatus of the present invention, an intermediate storage tank for storing the amount of the thermoplastic resin chips weighed by the first weighing mechanism and the amount of recycled chips weighed by the second weighing mechanism is provided. The thermoplastic to be supplied to the intermediate storage tank by the first and second weighing mechanisms while the thermoplastic resin chips and the recycled chips that have been weighed prior to the intermediate storage tank are stored. Since the resin chips and the recycled chips are controlled to be weighed individually, the extrusion molding mechanism can be efficiently used by using an intermediate storage tank having a capacity larger than that of the extrusion molding mechanism, for example. It becomes possible to manufacture a thermoplastic resin sheet having uniform characteristics while operating, with a high production rate, and it is possible to obtain a manufacturing apparatus suitable for mass production in particular.

[Brief description of drawings]

 FIG. 1 is an explanatory diagram showing an example of a manufacturing apparatus. 1 ... Thermoplastic resin chip storage tank 2 ... Thermoplastic resin chip weighing mechanism 3 ... Reused chip storage tank 4 ... Reused chip weighing mechanism 5 ... Intermediate storage tank, 6 ... Drying mechanism 7 …… Mixing mechanism, 8 extrusion molding mechanism 9 …… Vertical axis stretching mechanism, 10 …… Horizontal axis stretching mechanism 11 …… Transport mechanism, 12 …… Supply mechanism 13,14,15 …… Grinding and classification mechanism

Front page continued (72) Inventor Tomio Shioda 1 Sakura Sakura-cho, Hino-shi, Tokyo Within Roku Konishi Photo Industry Co., Ltd. (56) References JP 57-93118 (JP, A) JP 59-136228 (JP, A) JP 59-29204 (JP, U)

Claims (2)

[Claims] 1. A method comprising the steps of drying a mixture of thermoplastic resin chips and reusable chips obtained by collecting sheet waste produced from a manufacturing process, and then extruding and then biaxially stretching the thermoplastic resin chips. The resin chips and the recycled chips are weighed so as to have a certain ratio, and then supplied and stored in a common intermediate storage tank. From the intermediate storage tank, the thermoplastic resin chips and the thermoplastic resin chips are supplied to the subsequent manufacturing process including the drying process. Recycled chips are supplied, and while the thermoplastic resin chips and the recycled chips are stored in the intermediate storage tank, the thermoplastic resin chips and the recycled chips to be next supplied to the intermediate storage tank, respectively. The method for producing a thermoplastic resin sheet, comprising: 2. A thermoplastic resin sheet obtained by drying a mixture of thermoplastic resin chips and recycled chips obtained by collecting sheet waste generated from a manufacturing process, extrusion-molding the mixture, and then biaxially stretching it. An apparatus for manufacturing a thermoplastic resin chip, a first measuring mechanism for measuring a chip amount of the thermoplastic resin and a chip amount of the thermoplastic resin supplied from the tank, a reservoir for the recycled chip and the supply from the tank. A second weighing mechanism for weighing the amount of recycled chips to be used,
An intermediate storage tank, a transport mechanism for transporting the thermoplastic resin chips weighed by the first weighing mechanism and the recycled chips weighed by the second weighing mechanism to the intermediate storage tank, and a thermoplastic resin from the intermediate storage tank. A supply mechanism for supplying chips and reused chips to subsequent steps including a drying step, wherein the first weighing mechanism is provided while the thermoplastic resin chips and the recycled chips are stored in the intermediate storage tank. And a second measuring mechanism is controlled to measure each of the thermoplastic resin chips and the recycled chips to be supplied next to the intermediate storage tank. Manufacturing equipment.