JPH01161043A - Production of polyester resin composition - Google Patents

Abstract

PURPOSE:To obtain easily the present resin which can give a molding excellent in heat resistance and impact resistance and high in intrinsic viscosity, by melt- kneading polyethylene terephhalate with a specified (modified) PE and subjecting the resulting mixture to solid state polymerization. CONSTITUTION:100 pts.wt. polyethylene terephthalate of an intrinsic viscosity of 0.4-0.9 as measured in phenol/tetrachloroethane (50/50 by weight) at 25 deg.C is kneaded in a molten state with at least one member selected from PE (a) of a density <= 0.935 g/cm<3> and a modified PE (b) having 0.01-5 mol/kg of at least one kind of side chains, of formulas I-III, preferably, 0.1-20 pts.wt. mixture formed by mixing component (a) with component (b) at a weight ratio of 90-0/10-100, and the resulting mixture is subjected to solid state polymerization in a high vacuum or a stream of an inert gas.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention involves melt-kneading polyethylene and/or specific modified polyethylene into polyethylene terephthalate, and then
The present invention relates to a method for producing a polyester resin composition by solid phase polymerization.

[Prior Art and Problems to be Solved by the Present Invention] Polyethylene terephthalate is widely used in the fields of fiber, film, and plastic molding because of its excellent heat resistance, toughness, and chemical resistance. Furthermore, for molding applications, polyethylene terephthalate B is used as glass! a fiber, talc,
Attempts have also been made to further enhance these properties by melt-kneading inorganic fillers such as metal powders and different polymers such as polyolefins. In this case, it is known that the higher the intrinsic viscosity of the raw material polyethylene terephthalate, the better the mechanical strength, heat resistance, etc. of the molded product.

Therefore, conventionally, it has been common to melt-knead polyethylene terephthalate, which has a high intrinsic viscosity, with additives such as polyolefins, inorganic fillers, and stabilizers using a screw extruder. However, with this method, the melt viscosity of the polymer is high and the kneading action is difficult to work with, and hydrolysis and thermal decomposition occur during melting, so even if polyethylene terephthalate with a high intrinsic viscosity is used as a raw material, the intrinsic viscosity of the molded product obtained is quite low. There were problems such as a decrease in the performance. In order to prevent this, it is necessary to completely dry each raw material and knead it while shutting out outside air, which requires complicated and costly equipment. Furthermore, in order to prevent the intrinsic viscosity from decreasing, it is possible to set the melt viscosity low or shorten the residence time in the extruder, but this is not preferable because it weakens the kneading effect.

In this way, when producing a polyester resin composition by kneading polyolefin etc. with polyethylene terephthalate, a simple and rational method for producing a polyester resin composition that can obtain a molded product with a substantially high intrinsic viscosity has yet to be found. It was closed.

[Means for Solving the Problems] In view of the current situation, the present inventors conducted extensive studies and arrived at the present invention.

In other words, the gist of the present invention is that the intrinsic viscosity is 0.4.
Polyethylene with a density of 0.935 g/cm 3 or less and at least one type of side chain represented by formula (1) to formula (3) are added to the ioo weight part of polyethylene terephthalate of 0.9 or less. 0.1 to 20 parts by weight of at least one kind of polymer selected from the group consisting of modified polyethylene having a molecular weight of 0.01 to 5 moles/kg is kneaded in a molten state, and then solid phase polymerization is further carried out. This is a method for producing a polyester resin composition.

-C-OH-- (3) The object of the present invention is to perform a melt-kneading operation using polyethylene terephthalate, which has a low intrinsic viscosity, as a raw material when melt-kneading polyethylene, etc. to polyethylene terephthalate. The object of the present invention is to provide a polyester resin composition that is subsequently subjected to solid phase polymerization to increase the intrinsic viscosity that has been reduced by melt-kneading, thereby exhibiting desired mechanical strength, heat resistance, etc. Therefore, there is no need to strictly dry each material and shut off the outside air during melt-kneading. This is because, in the method of the present invention, even if the intrinsic viscosity of polyethylene terephthalate decreases during melt-kneading, it is possible to obtain a resin composition having the desired intrinsic viscosity by performing solid phase polymerization immediately before molding. It is.

The polyethylene terephthalate used in the present invention refers to a homopolymer of linear polyethylene terephthalate having ethylene terephthalate as a constituent unit - a copolymer of a small amount of other components that can be copolymerized with the unit component: a mixed resin of these homopolymers and copolymers. etc., but are not particularly limited to these. As other components that can be copolymerized here, conventionally known acid components and glycol components can be used, and specifically, for example, phthalic acid, isophthalic acid, adipic acid, sebacic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, diphenyl ether-4
, 4°-dicarboxylic acid; glycol components such as propylene glycol, butylene glycol, neopentyl glycol, cyclohexane dimetatool, 2,2-bis(4-hydroxyphenyl)propane; p-oxybenzoic acid, p Examples include oxyacids such as -hydroxybenzoic acid and p-hydroxyethoxybenzoic acid. The polyethylene terephthalate used in the present invention can be prepared by ordinary polymerization methods, such as polycondensation of terephthalic acid and ethylene glycol, and if desired, a small amount of other copolymer components by transesterification or direct esterification. You can get it.

In addition, since the reaction efficiency of solid phase polymerization is lower than that of melt polymerization, it is preferable that the intrinsic viscosity of the raw material polyethylene terephthalate is high, but if it is too high, the kneading effect will decrease, so 0.4
It is preferably 0.9 or less. In addition, the intrinsic viscosity mentioned here is phenol/tetrachloroethane = 50150 (
This is a value determined from the viscosity of a solution measured at 25° C. in a solvent (weight ratio).

0.01 mol/kg to 5 mol/kg of polyethylene with a density of 0.935 g/cm' or less used in the present invention and at least one type of side chain represented by formula (1) to formula (3)
The modified polyethylene containing g is added as a crystallization accelerator and impact resistance improver for polyethylene terephthalate.

If the density of polyethylene is greater than 0.935 g/cm', the elasticity will be lowered and the effect of improving impact resistance will be reduced, and the volumetric expansion upon heating will also be lowered and the effect of promoting crystallization will be reduced, which is not preferable.

In addition, modified polyethylene is effective as a crystallization accelerator and impact resistance improver for polyethylene terephthalate, and also improves the compatibility and affinity between polyethylene terephthalate and polyethylene, improving the dispersion of polyethylene particles and interfacial adhesion, resulting in higher It is preferably used because it has the effect of providing a sense of urban melancholy. These polyethylenes and modified polyethylenes can be used alone or in combination. The modified polyethylene mentioned here has at least one type of side chain represented by formulas (1) to (3) in the main chain of polyethylene. This side chain, carboxyl group or acid anhydride group, exhibits chemical affinity with polyethylene terephthalate and contributes to improved compatibility.

The larger the amount of side chains, the better the chemical affinity with polyethylene terephthalate, but at the same time it causes a decrease in thermal stability, so it is preferably 5 mol/kg or less. Furthermore, if the amount of side chains is extremely small, the affinity will be low and effects such as improving compatibility and interfacial adhesion cannot be obtained, so 0.01 mol/k
g or more is preferable.

In carrying out the present invention, it is preferable to use polyethylene and modified polyethylene in combination from the viewpoint of impact resistance and thermal stability. /10～O
/100 is preferable, and more preferably 80/20 to 20/80
is more preferable. The amount of polyethylene and/or modified polyethylene to be blended is preferably 0.1 to 20 parts by weight per 100 parts by weight of polyethylene terephthalate.

If it is less than 0.1 part by weight, the impact resistance effect will be small;
If it exceeds 0 parts by weight, it becomes thermally unstable and is not preferred.

Kneading of the resins blended at the above blending ratios is not particularly limited as long as it has a high shear force, but a screw extruder is generally used. Further, the mixing method may be a method in which all the materials are mixed at the same time, or a method in which a masterbatch is prepared from polyethylene and modified polyethylene and then kneaded with polyethylene terephthalate.

Solid phase polymerization as referred to in the present invention is a method in which a pellet-shaped or powdered polymer is polymerized under a high vacuum or under a flow of inert gas such as nitrogen at a temperature that does not cause fusion of polymer particles. .

The most significant feature of the present invention is the process of melt-kneading the polyethylene and/or modified polyethylene into polyethylene terephthalate and then performing solid phase polymerization. If the composition is prepared by the method described above, it can be subjected to solid phase polymerization in the same manner as in the case of polyethylene terephthalate alone.

In particular, it is preferable to add modified polyethylene because the reaction between the side chains and polyethylene terephthalate progresses through solid phase polymerization, improving compatibility.

The polyester resin composition obtained as described above can be made into a resin molded article having excellent heat resistance, impact resistance, etc. by a normal molding method, such as injection blow molding. Of course, the processing steps of the polyester resin composition obtained by the present invention, such as drying, molding, etc., are not limited.

Further, when carrying out the present invention, various additives such as inorganic fillers such as talc, stabilizers such as antioxidants, and mold release agents such as stearate may be added.

[Example] The present invention will be described in detail below with reference to Examples.

Examples 1 to 4 and Comparative Examples 1 to 4 Modified polyethylene having 2 mol/kg of side chains represented by the above formula (2) and density for 100 parts by weight of polyethylene terephthalate having an intrinsic viscosity [η] of 0.68 0.92
g/Cm3 of polyethylene was mixed in the amount shown in the table,
Eight types of pellets were produced by melt-kneading in a 40 mmφ-glaze extruder set at 280°C. After pre-crystallizing these pellets, they were placed in a solid phase polymerization machine set at 230°C and polymerized under a vacuum of 0.1 mmHg until the intrinsic viscosity [η] reached 1.1. Furthermore, these berets are 28
Eight types of sheets with a thickness of 0.5 mm were produced by melt extrusion from a T-die attached to the tip of an extruder set at 5°C.

Cut out a 5 cm square test piece from a part with uniform wall thickness,
A with a DuPont impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd.
50% fracture energy E, according to S T MD 2794-69. was measured (measurement temperature 23℃ and -30℃,
Load 100g or 200g, punch tip diameter 1/2 inch,
(1/2 inch inner diameter of pedestal).

Furthermore, the fractured surface of the test piece destroyed in the measurement at -30°C was observed with a scanning electron microscope to evaluate the adhesion state of the interface between polyethylene and polyethylene terephthalate. The display contents are ◎: R is also good, O: good, Δ: slightly poor, ×: poor. In addition, the same test piece used for the impact test was
The heat resistance was evaluated by holding the sample in a nitrogen stream for 10 hours and visually determining the presence or absence of discoloration.

These results indicate that heat resistance or impact resistance decreases outside the composition range effective in the present invention.

Comparative Example 5 Polyethylene and modified polyethylene in the amounts shown in the table were melt-kneaded in the same manner as in Example 3 to 100 parts by weight of solid-phase polymerized polyethylene terephthalate having an intrinsic viscosity [η] of 1.1 obtained in Comparative Example 1. and conducted the same evaluation. The results are shown in the table.

The results show that although the time required for solid phase polymerization was approximately the same and the compositions were the same, the impact resistance and heat resistance of this comparative example were deteriorated. This is because the intrinsic viscosity [η] of the polyester resin composition subjected to sheet extrusion was substantially 1.1 in Example 3, but in this comparative example, [η] decreased to 0.88 by melt-kneading. This is because.

This result proves the rationality of the process of the present invention.

Examples 5 and 6 Instead of the side chain represented by formula (2), modified polyethylene having 2.2 mol/kg of the side chain represented by formula (1) or 3 side chains represented by formula (3) was used. Bulleting, solid phase polymerization, and test pieces were prepared and evaluated in the same manner as in Example 3 except that modified polyethylene having a concentration of .0 mol/kg was used. These results are shown in the table.

As is clear from the results of Kowara, equations (1) to (3)
It can be seen that all of the side chains shown have similar effects.

Comparative Example 6 Bulleting, solid state polymerization, and sheet production were carried out in the same manner as in Example 3, except that polyethylene terephthalate with an intrinsic viscosity [η] of 0.98 was used instead of the polyethylene terephthalate used in Example 3. I performed the evaluation in the same way as before. As a result, a sufficient kneading effect due to the increase in melt viscosity could not be obtained, and when observed with an electron microscope, a large number of coarse particles were present. In addition, a decrease in heat resistance and impact resistance was observed, which seems to be due to poor dispersibility.

[Effects of the Invention] The present invention provides a method for producing a resin composition having excellent heat resistance and impact resistance by melt-kneading polyethylene and/or modified polyethylene with polyethylene terephthalate and then solid-phase polymerizing the mixture. be. This manufacturing method is extremely rational and has remarkable effects, such as simplifying the process and saving energy.

Claims (1)

[Claims] For 100 parts by weight of polyethylene terephthalate with an intrinsic viscosity of 0.4 or more and 0.9 or less, the density is 0.935 g/
Polyethylene of cm^3 or less and formulas (1) to (3)
0.1 to 20 parts by weight of at least one type of polymer selected from the group consisting of modified polyethylene having at least one type of side chain shown in 0.01 mol/kg to 5 mol/kg in a molten state. A method for producing a polyester resin composition, which comprises kneading and then solid-phase polymerization. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ --- (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ --- (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ --- (3)