JPH04372625A - Process for molding aromatic ether copolymer - Google Patents

Abstract

PURPOSE:To mold an aromatic ether copolymer without encountering unstable extrusion and poor intermeshing resulting in the poor quality of the molding by thermoforming pellets consisting of a specified aromatic ether copolymer and having a specified degree of crystallinity. CONSTITUTION:Pellets prepared from an aromatic ether polymer having repeating units of formulas I and II, a content of the repeating units of formula I (in terms of a molar ratio based on the total repeating units) of 0.2-0.4, a melt viscosity of 3000-100000P at 400 deg.C and a degree of crystallinity of 5% or above are thermoformed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding aromatic ether copolymers.

0002

[Prior art] Aromatic ether copolymers have heat resistance,
Not only does it have excellent flame retardancy and chemical resistance, but it is also thermoplastic and can be melt-molded by heating. For this reason, extrusion molding can produce filaments, films, sheets, tubes,
It is possible to obtain various molded products such as pipes and round bars. Various molded products such as flat plates and gears can also be obtained by injection molding.

[0003] This aromatic ether copolymer is produced by reacting dihalogenobenzonitrile, 4,4'-dichlorobenzophenone, and 4,4'-biphenol, as described in JP-A-2-255833, for example. A powder is obtained by washing and drying the obtained polymer. The obtained powder is in a crystalline state, but becomes amorphous by melt extrusion, cutting, and rapid cooling to pelletize. When these amorphous pellets are subjected to extrusion molding, plasticization rapidly progresses in the feeding section and/or compression section of the screw, changing the resin fluidity, causing instability in extrusion such as fluctuations in the extrusion amount, and molding. In addition to causing poor appearance and internal structural defects, in some cases the polymer can also stick to the screw, causing blockage and making extrusion impossible.

[0004] On the other hand, in injection molding of aromatic ether copolymers, amorphous pellets may melt and wrap around the screw when raw materials are supplied, resulting in so-called biting failure.

[0005]

OBJECTS OF THE INVENTION Therefore, it is an object of the present invention to provide a method by which an aromatic ether copolymer can be molded without causing extrusion instability or poor biting.

[0006]

[Structure of the Invention] The method for molding the aromatic ether copolymer of the present invention to achieve the above object is based on the general formula

[0007]

[Chemical formula 3]

and the formula

[0009]

[C4]

[0010]The content of the repeating unit represented by the formula [I] is 0.2 to 0.2 to the total amount of the repeating units represented by the above formulas [I] and [II]. 0.4, the melt viscosity at 400°C is 3,000 to 100,000 poise, and the crystallinity is 5%.
It is characterized by thermoforming the above pellets.

The present invention will be explained in detail below. The pellets used in the present invention are made of an aromatic ether copolymer. This aromatic ether copolymer has the general formula

0012

[C5]

and the formula

[0014]

[C6]

[I]/([I] ]+[II]) ] is 0.2 to 0.4 in molar ratio. As described in JP-A-2-255833, such an aromatic ether copolymer can be obtained by, for example, dihalogenobenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-biphenol. of the aromatic ether copolymer [
I]/([I]+[II]) is obtained by reacting at a ratio such that the above ratio is 0.2 to 0.4. The reason why [I]/([I]+[II]) is limited to 0.2 to 0.4 is that if it is less than 0.2, the melting point will be 400°C or higher, making molding difficult. If it exceeds 0.2 to 0.4, it becomes amorphous and the heat resistance decreases, whereas if it is in the range of 0.2 to 0.4, the heat resistance is excellent and the moldability is also good.

The aromatic ether copolymer has a plurality of repeating units [I] and a plurality of repeating units [II]
A block copolymer in which each block is a block copolymer,
A random copolymer in which repeating units [I] and repeating units [II] are randomly bonded, repeating units [I]
] and the repeating unit [II] may be alternately bonded to form an alternating copolymer.

400°C of this aromatic ether copolymer
The melt viscosity at is 3,000 to 100,000 poise. The reason is that when the melt viscosity is less than 3,000 poise, the heat resistance and mechanical strength are insufficient;
If it exceeds 00 poise, the moldability will deteriorate, whereas if it exceeds 3
,000 to 100,000 poise, the above problem does not occur.

In the present invention, the pellets made of the aromatic ether copolymer to be subjected to thermoforming are required to have a degree of crystallinity of 5% or more. The reason is the crystallinity of 5%.
If it is less than 100%, the polymer will undergo rapid plasticization in the feeding section and/or compression section of the screw in the extruder during extrusion molding, resulting in changes in resin fluidity, resulting in unstable extrusion and poor biting, which will affect the appearance of the molded product. This is because, whereas defects and internal defects are caused, when the amount is 5% or more, such problems do not occur. Particularly preferred is a crystallinity of 5 to 30%.

[0019] Such pellets having a crystallinity of 5% or more can be obtained by the following method. (i) After polymerization, the washed and dried aromatic ether copolymer powder is melt extruded into strands using an extruder at 350 to 420°C, the extruded strands are cut with a hot strand cutter, and slowly cooled. to obtain pellets with a crystallinity of 5% or more. (ii) After polymerization, the washed and dried aromatic ether copolymer powder is melt-extruded into strands using an extruder at 350 to 420°C, the extruded strands are slowly cooled and cut with a strand cutter to crystallize them. Obtain pellets with a degree of oxidation of 5% or more. (iii) After polymerization, the washed and dried aromatic ether copolymer powder is melt-extruded into a strand using an extruder at 350 to 420°C, and (a) the extruded strand is rapidly cooled using water or air. After solidification, the extruded strand is cut with a strand cutter, or (b) the extruded strand is cut at the exit of the die without being cooled (hot cut), and then the extruded strand is rapidly cooled and solidified with water or air. 0%) were obtained, and then the temperature was 220%.
After heat treatment at ~330°C for 1 minute to 10 hours, it is slowly cooled to obtain pellets with a crystallinity of 5% or more. The diameter of the pellet is not particularly limited, but is generally 1 to 5 mm. In addition, in the methods (i), (ii) and (iii) above,
Any type of extruder can be used, but in order to prevent oxidation of the resin during molding and to prevent the inclusion of air bubbles, it is preferable to use a nitrogen purge hopper, a vacuum hopper, or a vent type extruder.

In the present invention, the above-mentioned pellets having a crystallinity of 5% or more are thermoformed to obtain a molded article. Means of thermoforming include extrusion molding and injection molding. Extrusion molding is preferably carried out at a temperature of 350 to 420°C,
Molded products such as sheets, films, tubes, filaments, pipes, and round bars can be obtained by extrusion molding. Wire coating is also possible. In addition, injection molding is performed at a cylinder temperature of 350
It is preferable to carry out the injection molding at a temperature of ~420°C and a mold temperature of 180~240°C, and molded products such as flat plates and gears can be obtained by injection molding.

According to the present invention, by thermoforming aromatic ether copolymer pellets with a crystallinity of 5% or more, smooth extrusion can be achieved without causing instability of extrusion or poor biting due to fluctuations in extrusion amount. can be formed into
Furthermore, a molded product with excellent appearance and no internal structural defects can be obtained.

In the present invention, an amorphous molded product can also be obtained by rapidly cooling the molded product obtained after thermoforming. Moreover, it is also possible to make a molded product by heat-treating (annealing) and crystallizing the molded product once formed.

[0023]

[Example] The present invention will be further explained by the following example.
The present invention is not limited to these examples. Example 1 An aromatic ether-based random copolymer obtained by reacting 2,6-dichlorobenzonitrile with 4,4'-dichlorobenzophenone and 4,4'-biphenol was used. This aromatic ether copolymer has a repeating unit represented by the following formula:

[0024]

[C7]

The melt viscosity at 400° C. was 12,000 poise. This copolymer was supplied to a single screw extruder, and after melt extrusion at 400° C., the extruded strand was rapidly solidified in water, and cut with a strand cutter to form pellets. Then, the obtained amorphous pellet (
1.5 mm in diameter) was heat-treated at 270° C. for 2 hours to give a copolymer crystallinity of 25%. Next, the crystallized pellets were dried at 120°C for 24 hours, then fed to a single screw extruder, extruded at 400°C through a 200mm wide slit die (lip opening 0.5mm), and guided onto a cooling roll. By cooling and solidifying, an amorphous sheet with a thickness of 2 mm was obtained. The rotational speed of the screw during extrusion molding was 20 rpm, and the variation in the extrusion amount at this time was as small as 4%. Moreover, no defect in the appearance of the sheet was observed.

Comparative Example 1 A sheet was extruded in the same manner as in Example 1, except that the amorphous pellets in Example 1 were not crystallized by heat treatment at 270°C. In this case, the variation in the amount of extrusion from the slit die was as high as 10%. In addition, poor appearance of the sheet was also observed.

Example 2 Pellets of the same aromatic ether copolymer as in Example 1 were heat-treated at 230° C. for 10 minutes to obtain pellets with a copolymer crystallinity of 9%. A sheet was extrusion molded in the same manner as in Example 1 except that this crystallized pellet was used. In this case, the variation in the extrusion amount during sheet extrusion was as small as 5%. Moreover, no defect in the appearance of the sheet was observed.

Example 3 The same aromatic ether copolymer powder as in Example 1 was fed into a single screw extruder and extruded at 400°C, and the semi-molten strand extruded from the die was passed between pulleys. While being transported, it was slowly cooled in the air, taken out, and cut with a strand cutter to form pellets. The diameter of the obtained pellets was 2 mm, and the crystallinity was 17%. This pellet was molded into a sheet in the same manner as in Example 1. The variation in the amount of resin extruded during sheet molding was as small as 5%. Moreover, no defect in the appearance of the sheet was observed.

[0029]

[Effects of the Invention] As described above, the present invention provides a method for molding an aromatic ether copolymer without causing quality defects in molded products due to extrusion instability and poor biting. offered.

Claims (1)

[Claims] Claim 1: Consisting of repeating units represented by the general formula [Formula 1] and the formula [Formula 2], and the above formula [I]
The molar ratio of the repeating unit represented by formula [I] to the total amount of repeating units represented by [II] is 0.2 to 0.4, and the melt viscosity at 400°C is 3,000 to 100. A method for molding an aromatic ether copolymer, which comprises thermoforming pellets made of an aromatic ether polymer having a crystallinity of 5% or more and having a crystallinity of 5% or more.