JPH05245919A - Thermoformed product of polyphenyleneether resin sheet - Google Patents

Abstract

PURPOSE:To enable more beautiful appearance to be obtained by raising stability to heat of a thermoformed product by a method wherein the thermoformed product of a specific value in relative specific gravity is formed from polyphenyleneether resin sheet having respective specific contents in volatile component and water content. CONSTITUTION:Polyphenyleneether resin wherein a volatile component content of a sheet is 300-2000ppm and a moisture content is 250ppm or under is used, and a required sheet thermoformed product is obtained by thermoforming such as vacuum forming, air-pressure forming, etc. Inferiority of appearance such as generation of irregularities on a surface of the thermoformed product caused by foaming materials in a heating process of polyphenyleneether or the like is prevented from occurring thereby, and beautiful appearance is enabled to be obtained. The polyethyleneether resin is a polymer expressed by the general formula rightmentioned, which is obtained by, for example, making phenol as raw materials react with oxygen under presence of a complex of copper or manganese. In the formula, R1, R2 respectively represent a monovalent residual group of an alkyl group, an aryl group, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet molded product made of polyphenylene ether resin such as a vacuum molded product, a pressure molded product and a press molded product. More specifically, it relates to a thermoformed polyphenylene ether resin sheet having a beautiful appearance.

[0002]

2. Description of the Related Art Polyphenylene ether resin has heat resistance,
It is a resin with excellent electrical properties and has stable mechanical properties over a wide temperature range.
Most of them are used by injection molding in a wide range of fields, such as A machine field and automobile field. Among them, in recent years, attention has been paid to the automobile field, and the heat resistance of polyphenylene ether resin is
Application to exterior parts is being developed as an application that takes advantage of mechanical properties, especially impact resistance.

However, most of the exterior parts of automobiles are large, and large equipment is required for shaping by injection molding, which is not economical. Once the resin material has been processed into a sheet, vacuum molding is performed using an inexpensive die.
Alternatively, it is more economical to shape by a method such as pressure molding,
Suitable for high-mix low-volume production of diversified automobiles. Therefore, there is an increasing need for sheet extrusion molding of polyphenylene ether resin in place of conventional injection molding.

However, while the modified polyphenylene ether resin has excellent heat resistance, it requires high-temperature molding, so that
Therefore, there is a problem that deterioration is likely to occur. In the sheet extrusion molding, the heat deterioration of the resin has a particularly large influence on the appearance of the sheet. For example, gel and carbide caused by the heat deterioration are retained in the die lip and cause a poor appearance such as a die line or a lump.

Further, since a scrap material is generated in the sheet extrusion molding, it is necessary to recycle the resin material at a relatively high rate, and the physical property may be deteriorated due to heat deterioration of the resin during the recycle. Therefore, improvement of the thermal stability of the polyphenylene ether resin has become an essential subject for sheet extrusion molding, and various studies have been made.

[0006]

Under the circumstances as described above, the present invention conducts research on sheet thermoforming such as vacuum forming and pressure forming of a polyphenylene ether resin sheet,
An object of the present invention is to provide a thermoformed polyphenylene ether resin sheet having a beautiful appearance.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have made various improvements in thermal stability of polyphenylene ether resin to obtain a sheet having a beautiful appearance. Thermoforming of polyphenylene ether resin sheet for automobile exterior parts etc. The body began to be used. However, when the sheet was subjected to a detailed study of thermoforming such as vacuum forming and pressure forming, the polyphenylene ether resin was a resin with a low water absorption rate, but the foaming of the material in the heating process caused the surface It was found that the appearance defects such as unevenness frequently occur on the surface.

Therefore, as a result of intensive studies on the appearance defect of the polyphenylene ether resin sheet thermoformed product due to foaming of the material, the defective appearance of the molded product due to foaming is closely related to the amount of volatile components and the amount of water contained in the material. In the critical moisture content region (150 to 250 ppm) in which material foaming occurs or does not occur, a sheet having a volatile component content within a specific range is a sheet below the range. In comparison with the above, the present inventors have obtained the knowledge that appearance defects due to foaming of materials are unlikely to occur, which has never been obtained.

That is, in the critical water content region, if the content of the volatile component of the sheet exceeds 2000 ppm, material foaming is likely to occur in the heating step, and the degree of foaming is large, so that the appearance defect due to material foaming is likely to occur. Conversely, if the volatile component content of the sheet is less than 300 ppm, 300
The present invention has been completed by discovering the fact that the size of bubbles when a material is foamed is larger than that of a sheet of 2000 ppm to 2000 ppm, so that it has a large influence on the appearance of a molded body and is likely to cause defective appearance.

That is, the present invention has a volatile component content of 3
0 to 2000 ppm, water content is 250 pp
It is a thermoformed product having a relative specific gravity of 1.0 to 0.95, which is made of a polyphenylene ether resin sheet having a size of m or less, and provides a polyphenylene ether resin sheet thermoformed product having a beautiful appearance.

The volatile component content of the polyphenylene ether resin sheet used in the thermoformed polyphenylene ether resin sheet of the present invention is set to 2000 ppm or less because the water content is 250 ppm or less when the volatile component content exceeds 2000 ppm. This is because the material is likely to foam even if it is suppressed to, and a defective appearance of the molded product easily occurs due to foaming.
In addition, the volatile component content of 300 ppm or more,
When the content of the volatile component is less than 300 ppm, when the material is foamed, the size of the bubbles becomes large, so that the influence on the appearance of the molded body becomes large, and the appearance of the molded body such as unevenness is likely to occur.

The water content is set to 250 ppm or less when the content of the volatile component is in the range of 300 to 2000 ppm and the water content of 150 to 250 ppm is the critical region where the material foaming starts and the material foaming occurs. Even in this case, the cell size is small, the degree of foaming is also small, and there is almost no effect on the appearance. The presence or absence of foaming inside the molded body and the degree of foaming are determined by cutting the specific gravity of the molded body itself and cutting a small piece from the molded body, and pressing the small piece under warm conditions (30 to 5 depending on the glass transition temperature of the material forming the molded body).
It is expressed by the ratio of specific gravities (hereinafter referred to as relative specific gravities) when measured with a state where no bubbles are present inside the material by press treatment at a temperature higher by 0 ° C.).

The relative specific gravity of the sheet thermoformed body of the present invention is 0.
The reason why it is set to 95 to 1.0 is that if the relative specific gravity is less than 0.95, the degree of foaming is too large and the appearance is poor. Even if the water content is 250 ppm or less, if the volatile component content is less than 300 ppm, when the material foams,
The bubble size becomes large, resulting in poor appearance. It may be particularly noted that there is a phenomenon that a defective appearance is likely to occur due to foaming in a region where both the volatile component content and the water content are low. The polyphenylene ether resin referred to in the present invention has the general formula

[0014]

[Chemical 1] (In the formula, R ₁ and R ₂ represent monovalent residues such as the same or different alkyl groups, aryl groups, halogen, hydrogen, etc., and n represents the degree of polymerization), for example, copper, Alternatively, it can be obtained by reacting the starting phenol with oxygen in the presence of a manganese complex.

Specific examples include poly (2,6-dimethyl-1,4-phenylene) ether, poly (2,6-diethyl-1,4-phenylene) ether, poly (2,6-).
Dichloro-1,4-phenylene) ether, poly (2,2
6-dibromo-1,4-phenylene) ether, poly (2-methyl-6-ethyl-1,4-phenylene) ether, poly (2-chloro-6-methyl-1,4-phenylene) ether, poly ( 2-Methyl-6-isopropyl-1,4-phenylene) ether, poly (2,6-di-
n-propyl-1,4-phenylene) ether, poly (2-chloro-6-bromo-1,4-phenylene) ether, poly (2-chloro-6-ethyl-1,4-phenylene) ether, poly ( 2-Methyl-1,4-phenylene) ether, poly (2-chloro-1,4-phenylene) ether, poly (2-phenyl-1,4-phenylene) ether, poly (2-methyl-6-phenyl-) 1,
4-phenylene) ether, poly (2-bromo-6-phenyl-1,4-phenylene) ether and the like. Further, these polymers may be treated with maleic anhydride, a styrene compound or the like. Further, these polyphenylene ether and rubber-reinforced polystyrene, and / or polyamide, polypropylene, PET, PBT, PPS
It may be a polymer alloy composed of the like.

The rubber-reinforced polystyrene referred to in the present invention is
It is a resin containing a styrene-based polymer as a reinforcing component and a conjugated gen-based rubber dispersed in an island shape. Examples of the conjugated gen-based rubber include polybutadiene (including low-cis polybutadiene and high-cis polybutadiene) styrene-butadiene copolymer polyisoprene, butadiene-isoprene copolymer, natural rubber, and the like. It is polybutadiene.

A particularly preferred rubber-reinforced polystyrene of the present invention is a rubber-reinforced polystyrene containing a conjugated gen-based rubber in which 10% or more of double bonds having excellent thermal stability are hydrogenated. A compatibilizing agent is added to an incompatible polymer alloy such as polyphenylene ether or a styrene compound of polyphenylene ether and polyamide, polyolefin, PET, PBT, PPS resin, etc., for example, maleic anhydride is introduced as a functional group. A styrene resin or a graft polymer composed of a polymer in which the trunk and the branches are compatible with each other is used.

For the purpose of improving the impact properties of the above resin composition, for example, a block copolymer of a conjugated gen, preferably a conjugated gen in which 20% or more of double bonds are hydrogenated, and a styrene compound, And / or it is possible to add a thermoplastic elamatomer of a modified block copolymer having a molecular unit containing a carboxylic acid or a derivative group thereof having improved compatibility bonded thereto, and various additives such as a flame retardant depending on the purpose. Glass fiber, carbon fiber, asbestos, carbon calcium, talc, mica, zinc oxide and the like can also be added as a plasticizer, a stabilizer or a reinforcing filler.

As the flame retardant, phosphorus compounds such as triphenyl phosphate, oligo-organic phosphates,
Halogen compounds such as decabromodiphenyl oxide are used. As the stabilizer, phosphite-based antioxidants, hindered phenol-based antioxidants and the like are used.

The sheet referred to in the present invention has a thickness of 0.3 mm.
The above-mentioned plate-shaped molded product is meant and is usually obtained by extrusion molding. A sheet having a thickness of 2 to 5 mm is mainly used as a base plate for thermoforming such as vacuum forming. The sheet thermoformed body according to the present invention means a molded product obtained by applying some external force in a state where the sheet is heated and softened, while being deformed, and cooled, for example, a vacuum molded product, a pressure molded product, Refers to pressed products and bent products.

The heating temperature of the sheet for obtaining the thermoformed polyphenylene ether resin sheet of the present invention varies depending on the composition of the resin. For example, in the case of a styrene type polyphenylene resin sheet, the heat distortion temperature (ASTM-D64) of the sheet.
8 It is preferable to set the temperature 40 to 90 ° C. higher than the bending stress applied to the test piece (18.5 kgf / cm), which is about 160 to 210 ° C.

In order to obtain a polyphenylene ether resin sheet molded product having a beautiful appearance (no defective appearance due to foaming of the material) in the above temperature range, the volatile component content is slightly different depending on the heating form and heating conditions. 300 ~
It is in the range of 2000 ppm and has a water content of 250.
Sheets below ppm, preferably with a water content of 200 p
It is necessary to use a sheet of pm or less, more preferably 150 ppm or less. It is particularly noticeable that there is a critical point of water content in such a low region which does not cause a defective appearance due to foaming.

The volatile components contained in the polyphenylene ether resin sheet used in the present invention include a polymerization solvent contained in the polyphenylene ether, residual monomers and oligomers, rubber-reinforced polystyrene polymer and polyamide. And residual monomers and oligomers contained in the polyolefin, the polymerization solvent, especially volatile components produced by thermal decomposition of styrene-based polymerization, specifically, styrene monomer, ethylbenzene, toluene, xylene, tetrahydrofuran, Examples include pyridine, styrene dimer, and styrene trimer. Among these, volatile components that are likely to remain in the resin sheet of the present invention include styrene monomer, ethylbenzene, xylene, and styrene dimer.

More specifically, the volatile components referred to in the present invention are those measured by gas chromatography (detector FID) using a solution in which a resin component is dissolved in chloroform, such as styrene monomer, xylene, A component such as ethylbenzene is PEG-20M 25 as a column packing material.
% Of styrene dimer and styrene trimer can be measured at 190 ° C. and 260 ° C., respectively, using 3% of silicon OV-17 as a column packing material.

The components of the retention time before the styrene trimer are summed to obtain the total volatile components in the resin sheet. The molecular weight of these volatile components is usually 320 or less. The water content of the polyphenylene ether resin sheet used in the present invention can be measured by a Karl Fischer method moisture meter. When measuring moisture, it is necessary to perform the measurement promptly, taking care that moisture does not adhere to the sample during measurement work and that the sample does not absorb moisture as much as possible.

Specifically, the sheet is finely cut into pellets using a nipper and a polyethylene resin experimental bag in a constant temperature and humidity chamber at 23 ° C. and 50% RH so that moisture on the hands does not adhere to the sheet. Then, a sample of about 1 to 3 g is rapidly prepared, and then the sample is inserted into a cell purged with nitrogen, heated, and the water content of the sample is extracted using meta-cresol or the like.

In the present invention, the relative specific gravity is the specific gravity of the molded article itself (when the molded article is coated, excluding the coating layer, the specific gravity measured without any influence of the coating) as a molecule, and the molded article A small piece (about 5 cm square) is cut from the above, and the small piece is pressed at a temperature of 100 to 300 at a temperature 40 to 70 ° C. higher than the glass transition temperature of the material forming the molded body.
Pressing is performed by applying a resin pressure of kg / cm. If there is a coating layer, the coating layer should be scraped off before processing to show the value with the specific gravity as the denominator when measured with no air bubbles inside the material and the degree of foaming of the molded product. ..

For example, a value of 1.0 indicates that the molded body is not foamed, and the smaller the value, the greater the degree of foaming of the molded body. The specific gravities of the molded product and the melt-processed molded product are obtained by measurement using ordinary buoyancy. The method for producing the sheet of the present invention is not subject to any limitation, but a preferred method is a method of reducing the pressure of the vent portion by using a vented extruder when producing the sheet. More preferably, an extruder having two or three vent portions is used.

The depressurized state of the vent portion is preferably-
A reduced pressure state higher than 600 mmHg, and more preferably higher than -700 mmHg is good. It should be noted that if the reduced pressure level in the vent portion is low, the content of volatile components may exceed the range of the present invention. Since the volatile component content may be lower than the present invention when reclaiming scraps and mill ends of a sheet formed by a vented extruder, the volatile component content of the sheet to be formed is less than that of the present invention. It is necessary to determine the reproduction rate and the number of times of reproduction so that they fall within the range.

Since the water content of the sheet is small immediately after plate making, it is preferable to perform thermoforming as soon as possible after plate making. If the water content of the sheet exceeds the range of the present invention during storage, it is necessary to pretreat the sheet so that the water content of the sheet falls within the range of the present invention before thermoforming the sheet.

The treatment method is, for example, 20 to 3 depending on the heat deformation temperature of the sheet (18.5 kgf / cm of bending stress applied to the ASTM-D648 test piece) before thermoforming.
A method of pre-drying with hot air for 12 hours or more at a low temperature of 0 ° C or a thermoforming machine having a function of heating a sheet stepwise is a method of performing preheating once near the heat distortion temperature of the sheet and then performing main heating. Etc.

[0032]

EXAMPLES Hereinafter, the thermoformed polyphenylene ether resin sheet of the present invention will be specifically described with reference to Examples and Comparative Examples.

Examples 1 to 3 and Comparative Examples 1 to 7 (1) Trademark Cylon X9653 (alloy of PPE and styrene resin; heat distortion temperature 120 ° C., Asahi Kasei Kogyo KK)
Made by melt compression molding at a temperature of 260 ° C and a thickness of 3 m
An m, 400 mm square polyphenylene ether resin flat plate was prepared. (2) Similarly, using Zylon X9653 in an extruder with a 45 mm vent, a width of 500 mm and a thickness of 3 at a temperature of 270 ° C.
mm polyphenylene ether resin sheet was molded.

The vent section of the extruder was operated under a reduced pressure of -700 mmHg. Then, the flat plate obtained by compression molding is not heat treated, and the sheet obtained by extrusion molding is 400 mm.
Cut into square original size for vacuum forming, one is not heat treated, the other is vacuum dried at 150 ° C for 6 hours and 8 hours, and then is left as it is without attaching a masking film (protective paper). Then, the original plate was allowed to stand in a constant temperature and humidity chamber at 23 ° C. and 50% RH, and aged samples having different volatile component content and water content were taken.

Then, the volatile component content and the water content of the aged sample were measured and a vacuum forming machine was used to measure 35
Double-sided radiant heating with a far infrared heater set at 0 ° C,
When the surface temperature of the sample reached 180 ° C., the sample was quickly vacuum-molded to obtain the molded body of FIG. Then, after measuring the specific gravity of the obtained molded body, the presence or absence of internal foaming of the molded body and the sheet appearance were examined.

The heating temperature of the sample was detected by attaching Thermolabel-H (manufactured by NOF Giken Industry Co., Ltd.) to the original plate. The heating temperature of 180 ° C. is a temperature at which the material has a viscosity that allows good vacuum forming. The volatile component content of the sample was calculated by dissolving the resin component in chloroform and then measuring the volatile component using gas chromatography.
The water content of the sample was measured using a Kyoto Electronics ADP351 Karl Fischer water content meter, Method 1 (185 ° C.).
Temperature conditions).

The relative specific gravity was determined by A / B. A: Specific gravity of the molded body B: Cut a small piece of about 5 cm square from the molded body, sandwich the small piece with a polyimide film having a thickness of 50 μ, and press at a temperature of 200 ° C. with a resin pressure of 200 kg / cm for 5 minutes. After that, the specific gravity of the measured small piece was measured by a method utilizing buoyancy.

The results are shown in Tables 1 to 4. In particular, Examples 2 and 3
And as shown in Comparative Examples 2 and 6, the content of volatile components,
It can be seen that the sheet thermoformed article comprising the polyphenylene ether resin sheet having a water content within the range of the present invention has a good appearance.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

INDUSTRIAL APPLICABILITY The present invention expands the use of the polyphenylene ether resin in the field of thermoforming of sheets, and has a great effect of improving the foaming defect on the surface particularly in vacuum forming.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a molded body obtained by vacuum molding in an example.

Claims (1)

[Claims] 1. A volatile component content of 300 to 2000 p.
A thermoformed product, which is made of a polyphenylene ether resin sheet having a water content of 250 ppm or less and a relative specific gravity of 1 to 0.95.