JPS62201225A - Manufacture of thermoplastic resin sheet and device thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for producing a thermoplastic resin sheet used as a support for photographic film such as X-ray film.

[Technology background]

For example, a thermoplastic resin sort used as a support for a photographic film such as an X-ray film is usually produced by drying and extrusion molding of thermoplastic resin chips, followed by biaxial stretching.

As the thermoplastic resin chips, powder in the form of square or columnar pieces of several mm in size is usually used.

However, in the production of thermoplastic resin sheets, sheet waste is usually generated after extrusion molding or biaxial stretching, that is, after longitudinal and transverse stretching. If the sheet waste produced in such a manufacturing process can be reused, the yield will be high and thermoplastic resin sheets can be manufactured economically.

In addition, in order to obtain thermoplastic resin sheets with uniform properties, it is necessary to maintain a constant mixing ratio of recycled chips obtained by collecting sheet waste generated during the manufacturing process and thermoplastic resin chips. be done. This is because reused chips have already been heated during extrusion molding, so their physical properties, such as intrinsic viscosity when melted, are slightly different from newly used thermoplastic resin chips.
This is because unless the mixing ratio is constant, a thermoplastic resin sheet with uniform properties cannot be obtained. In addition, when manufacturing colored thermoplastic resin sheets, since the recycled chips have a specified concentration, the mixing ratio of the recycled chips and the thermoplastic resin chips should be adjusted to prevent uneven coloring. It is necessary to keep it constant.

[Problem that the invention seeks to solve]

From this point of view, when adding reprint chips to new thermoplastic resin chips, it is necessary to weigh each chip before mixing the two. In the process of manufacturing thermoplastic resin sheets, it is especially economical to supply raw materials in a flow that is adapted to the capacity of the extrusion molding mechanism.

However, when the capacity of the extrusion molding mechanism is large,
This increases the amount of thermoplastic resin chips and reused chips that must be weighed in the weighing process, which requires a considerable amount of time.Therefore, the waiting time for the next step, drying, is longer, which results in slower manufacturing times. There are problems in that the process cannot be carried out efficiently and energy for heating is wasted in the extrusion molding process at the start.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its purpose is to be able to measure raw materials with high precision, and to quickly transfer the weighed raw materials to each manufacturing process without requiring waiting time. It is an object of the present invention to provide a manufacturing method and apparatus that can efficiently manufacture thermoplastic resin sheets with uniform properties.

[Means for solving problems]

The method for manufacturing a thermoplastic resin sheet of the present invention includes drying a mixture of thermoplastic resin chips and recycled chips obtained by collecting sheet waste generated from the manufacturing process, and then drying the mixture.
The process includes extrusion molding and then biaxial stretching, in which weighed thermoplastic resin chips and recycled chips weighed at a certain ratio are stored in a common intermediate storage tank, and from this intermediate storage tank. It is characterized in that thermoplastic resin chips and recycled chips are supplied to subsequent manufacturing processes.

In addition, the manufacturing apparatus of the present invention dries a mixture of thermoplastic resin chips and recycled chips obtained by collecting sheet waste generated from the manufacturing process, extrudes the mixture, and then biaxially stretches the mixture to form thermoplastic resin chips. An apparatus for manufacturing a resin sheet, comprising: a storage tank for thermoplastic resin chips; a measuring mechanism for measuring the amount of thermoplastic resin chips supplied from the storage tank; and a storage tank for recycled chips and a measuring mechanism for measuring the amount of thermoplastic resin chips supplied from the storage tank. a measuring mechanism for measuring the amount of pulverized sheet waste, an intermediate storage tank, a transport mechanism for transporting the amount of thermoplastic resin chips and recycled chips measured by the respective measuring mechanisms to the intermediate storage tank, and from the intermediate storage tank. It is characterized by comprising a supply mechanism for supplying thermoplastic resin chips and recycled chips to subsequent processes.

According to this method, the thermoplastic resin chips and the recycled chips are not immediately subjected to the subsequent process after being weighed, but are temporarily stored in an intermediate storage tank, so that this intermediate storage tank functions as a buffer. Therefore, the weighed thermoplastic resin depth and reprint chip 7
It can be quickly supplied to the subsequent process without having to wait for the next process, and the next thermoplastic resin can be supplied to the next process while already weighed thermoplastic resin chips and recycled chips are stored in the intermediate storage tank. Since resin chips and recycled chips can be weighed, sufficient time can be taken for weighing and the weighing can be carried out with high precision, resulting in thermoplastic resin sheets with uniform properties. can be manufactured with high efficiency.

Further, according to the manufacturing apparatus of the present invention, since the intermediate storage tank is provided for storing the thermoplastic resin chips and the recycled chips in the amount measured by the measuring mechanism, the intermediate storage tank can be used for example by the capacity of the extrusion molding mechanism. By using a larger capacity, it is possible to manufacture thermoplastic resin sheets with uniform properties at a high production rate without operating the extrusion mechanism efficiently, making this manufacturing equipment particularly suitable for mass production. can be obtained.

The present invention will be explained in detail below.

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

Then, the thermoplastic resin chips and the reused chips stored in the intermediate storage tank are subjected to a subsequent process such as a drying process to dry them, and then, if necessary, to a mixing process to mix them together, and after dry mixing, The thermoplastic resin chips and recycled chips are subjected to an extrusion molding process to be extruded and then biaxially stretched, that is, longitudinally stretched and transversely stretched, thereby producing a thermoplastic resin sheet.

During this time, for example, once the metered amount of thermoplastic resin chips and reusable chips has been supplied to the intermediate storage tank, the next weighing of thermoplastic resin chips and reusable chips is immediately started. When the thermoplastic resin chips and recycled chips stored in the intermediate storage tank are supplied to the subsequent process and become empty, the measured amount of thermoplastic resin chips and recycled chips are immediately transferred to the intermediate storage tank. and store it here.

For example, when carrying out a batch-type manufacturing process, it is necessary to weigh the amount of thermoplastic resin chips and recycled chips equivalent to one batch, so the intermediate storage tank has a capacity of one batch. It is preferable to use an amount slightly larger than the amount equivalent to 1 minute. By doing this, during the drying period of thermoplastic resin chips and reused chips, it is possible to take sufficient time to weigh the thermoplastic resin chips and crushed sheet waste necessary for one batch. Therefore, the measurement accuracy can be increased. After the drying is completed and the dried thermoplastic resin chips and recycled chips are subjected to the extrusion molding process, the thermoplastic resin chips and recycled chips for one batch stored in the intermediate storage tank are immediately can be subjected to subsequent steps by means such as pneumatic transport, so that subsequent steps can be carried out quickly without waiting time.

Recycled chips are produced by collecting sheet scraps generated during the manufacturing process, that is, after extrusion molding, longitudinal stretching, and transverse stretching, pulverizing them, and classifying them using a screen, etc., as necessary. A pulverized product of several mm in size obtained by pulverizing the collected sheet waste or a granulated product obtained by further semi-melting and processing into a size of several mm can be used.

As the thermoplastic resin chips, for example, powder in the form of square pieces of several mm or cylindrical pieces of several mm is used, and as the thermoplastic resin, polyester resin can generally be suitably used. It is not limited. Particularly suitable polyester resins are those whose acid component is mainly terephthalic acid and whose alcohol component is mainly ethylene glycol, but may contain other acid components and/or alcohol components.

Such other acid components include isophthalic acid, naphthalene dicarboxylic acid with one or two -h groups, β-hydroxyethoxybenzoic acid, p-hydroxybenzoic acid, adipic acid, sepacic acid, etc. , and other alcohol components include trimethylene glycol,
One or more types of fatty acids or alicyclic or aromatic dioxy compounds such as tetramethylene glycol, hexamethylene glycol, 1,4-cyclohexane dimetatool, and polyalkylene glycols such as polyethylene glycol can be mentioned. can.

Preferred polyester resins are those in which at least 80 mole percent of the repeating structural units are ethylene terephthalate units.

By using such a polyester resin, a strong and thin sheet can be easily produced, but on the other hand, it is easily hydrolyzed, so it is important to dry it sufficiently in the drying process.

According to the above manufacturing method, after weighing the thermoplastic resin chips and the recycled chips, they are not immediately subjected to the subsequent process, but are temporarily stored in an intermediate storage tank, so that this intermediate storage tank functions as a buffer. It became like this,
Therefore, weighed thermoplastic resin chips and recycled chips can be quickly supplied to the subsequent process without waiting time, and the already weighed thermoplastic resin chips and recycled chips can be stored in an intermediate storage tank. Since the next thermoplastic resin chip and reusable chip can be weighed while they are stored in As a result, thermoplastic resin sheets with uniform properties can be manufactured with high efficiency.

FIG. 1 is an explanatory diagram schematically showing an example of a manufacturing apparatus of the present invention. 1 is a storage tank for thermoplastic resin chips, 2 is a measuring mechanism for weighing thermoplastic resin chips, 3 is a storage tank for recycled chips, 4 is a measuring mechanism for weighing recycled chips, and 5 is a measured amount of heat. An intermediate storage tank for storing plastic resin chips and recycled chips together; 6 is a drying mechanism; 7 is a mixing mechanism; 8 is an extrusion molding mechanism; 9 is a longitudinal stretching mechanism; 10 is a horizontal stretching mechanism; 11 is a transporting mechanism. mechanism, 12 is a supply mechanism, 13
, 14 and 15 are crushing and classifying mechanisms for obtaining reusable chips by crushing and classifying sheet waste generated after extrusion molding, longitudinal stretching, and horizontal stretching, respectively.

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

In the weighing mechanisms 2 and 4, an amount of thermoplastic resin chips and a reprint tray corresponding to, for example, one batch are weighed, respectively, and the measured amounts of thermoplastic resin chips and recycled chips are, for example, air-filled. First, it is transported to the intermediate storage tank 5 by a transport mechanism 11 equipped with a transport means, and is temporarily stored there.

After the weighed thermoplastic resin chips and recycled chips are transported to the intermediate storage tank 5 in this way, the weighing mechanisms 2 and 4 immediately produce thermoplastic resin chips and reused chips in an amount equivalent to the next batch. Weighing of reusable chips begins. Then, the thermoplastic resin chips and recycled chips in the intermediate storage tank 5 are transferred to the subsequent drying mechanism 6 by the supply mechanism 12.
Immediately after being supplied to the container, the weighed thermoplastic resin chips and reusable chips are transported by the transportation mechanism 11 to the empty intermediate storage tank 5, where they are temporarily stored, and the same operation is repeated thereafter.

In the drying mechanism 6, thermoplastic resin chips and recycled chips in an amount equivalent to one batch are supplied from the intermediate storage tank 5 and are subjected to a drying process.

The dried thermoplastic resin chips and the recycled chips are then supplied to a mixing mechanism 7, where they are thoroughly mixed, and then supplied to an extrusion molding mechanism 8, where they are heated and melted before being extruded. molded and then vertically stretched by a longitudinal stretching mechanism 9
The sheet is vertically stretched by a transverse stretching mechanism 10, and then horizontally stretched by a transverse stretching mechanism 10, thereby obtaining a thermoplastic resin sheet having a thickness of usually about 75 to 175 .mu.m.

During the manufacturing process, the sheet waste generated after extrusion molding is crushed and classified by the crushing and classification mechanism 13 to become reusable chips, and then transported to the storage tank 3, and the sheet scraps generated after longitudinal stretching are crushed and classified by the crushing and classification mechanism 13. The sheet waste produced after horizontal axis stretching is crushed and classified by a crushing/classifying mechanism 15 to become reusable chips, and then transported to the storage tank 3. transported and reused.

According to the above-described manufacturing apparatus, since the intermediate storage tank 5 is provided for storing together the thermoplastic resin chips and the reused chips in the amounts measured by the measuring mechanisms 2 and 4, the intermediate storage tank 5 may be, for example, By using a larger capacity than the extrusion molding mechanism 8, it becomes possible to manufacture thermoplastic resin sheets with uniform properties at a high production rate without operating the extrusion molding mechanism 8 efficiently. A manufacturing device suitable for mass production can be obtained.

Although the above description has been made based on an example of a manufacturing apparatus, various embodiments are possible in the present invention.

For example, when used as a support for an X-ray film, a thermoplastic resin sheet colored with, for example, fine powder of a blue dye may be required in order to make the image easier to see during diagnosis using the X-ray film. In order to construct an apparatus capable of producing colored thermoplastic resin sheets in this manner, the apparatus is constructed by adding necessary components such as a storage tank for fine dye powder. Such fine dye powder usually has an average particle size of 1
Fine particle powder of about 5 to 30 nanometers is used.

When obtaining a colored thermoplastic resin sheet, the coloring density is selected to be an appropriate value as necessary in relation to the application and is not necessarily limited, but generally, the coloring density is 200 to 200 for colored thermoplastic resin sheets. 300ppm
It is preferable to select the content ratio of the fine dye powder so as to have an appropriate value within the range of (weight). Further, as the fine dye powder, fine powder of anthraquinone dye can generally be used, but it is not limited thereto.

〔Effect of the invention〕

□ As described above, according to the method for manufacturing a thermoplastic resin sheet of the present invention, the thermoplastic resin chips and recycled chips are not directly subjected to the subsequent process after being weighed, but are stored in an intermediate storage tank. This intermediate storage tank then functions as a buffer, so that weighed thermoplastic resin chips and recycled chips can be quickly supplied to the subsequent process without any waiting time, and even if they are already The next thermoplastic resin chips and reusable chips can be weighed while the weighed thermoplastic resin chips and reused chips are stored in the intermediate storage tank, so there is sufficient time for weighing. As a result, thermoplastic resin sheets with uniform properties can be manufactured with high efficiency.

Further, according to the manufacturing apparatus of the present invention, since the structure includes an intermediate storage tank for storing together the thermoplastic resin chips and the recycled chips in the amounts measured by the measuring mechanism,
For example, by using a capacity larger than the capacity of the extrusion molding mechanism as this intermediate storage tank, it is possible to manufacture thermoplastic resin sheets with uniform properties at a high production rate without operating the extrusion molding mechanism efficiently. Therefore, it is possible to obtain a manufacturing apparatus particularly suitable for Ooki souvenirs.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a manufacturing apparatus. 1... Storage tank for thermoplastic resin chips 2... Measuring mechanism for thermoplastic resin chips 3... Storage tank for recycled chips

Claims (1)

[Claims] 1) The process includes the step of drying a mixture of thermoplastic resin chips and recycled chips obtained by collecting sheet waste generated from the manufacturing process, extrusion molding, and then biaxial stretching. , The weighed thermoplastic resin chips and the recycled chips weighed at a certain ratio are stored in a common intermediate storage tank, and the thermoplastic resin chips and recycled chips are transferred from this intermediate storage tank to the subsequent manufacturing process. A method for producing a thermoplastic resin sheet, the method comprising: supplying a used chip. 2) After drying a mixture of thermoplastic resin chips and recycled chips obtained by collecting sheet waste generated from the manufacturing process, the mixture is extruded and then biaxially stretched to produce a thermoplastic resin sheet. An apparatus comprising: a storage tank for thermoplastic resin chips; a measuring mechanism for measuring the amount of thermoplastic resin chips supplied from the storage tank; and a storage tank for recycled chips and an amount of pulverized sheet waste supplied from the storage tank. a weighing mechanism for weighing thermoplastic resin chips and recycled chips, an intermediate storage tank, a transport mechanism for transporting the thermoplastic resin chips and recycled chips in the amount measured by the respective weighing mechanisms to the intermediate storage tank; 1. An apparatus for manufacturing a thermoplastic resin sheet, comprising a supply mechanism for supplying recycled chips to a subsequent process.