JP2682638B2 - Method for producing polyester resin molded article - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a crystalline polyester resin composition having improved impact strength and the like and a method for producing the polyester resin molded product.

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS THEREOF Molded articles made of polyester resin are widely used for various containers because of their excellent properties such as transparency and gas barrier property. Further, when crystallized, transparency is lost, but excellent heat resistance is obtained.

It is desirable that the polyester resin molded body used for such an application has a certain degree of crystallinity and excellent impact strength.

As a method of improving the crystallization rate of a polyester resin, a method of adding an inorganic powder such as talc, gypsum, silica, calcium carbonate, alumina and titanium dioxide to the polyester resin as a crystallization accelerator is known.
The addition of these crystallization accelerators improves the crystallization rate of the polyester resin molded body to some extent, but the addition of the crystallization accelerators does not show a marked improvement in impact strength.

On the other hand, U.S. Pat. Nos. 3,960,807, 4,571,952 and JP-A-59-62660 disclose that polyolefins are effective as impact strength improvers for polyester resins.

However, according to the study of the present inventor, the impact strength of the polyester resin is often not sufficiently improved even when the polyolefin is added to the polyester resin, and the crystallization rate of the polyester resin is not improved even when the polyolefin is added to the polyester resin. It has been found that it is not sufficiently improved and it is difficult to control the crystallization rate by the addition amount.

OBJECT OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and the present invention provides a method for producing a polyester resin molded article which has improved impact strength and is sufficiently crystallized. Is intended to provide.

SUMMARY OF THE INVENTION A method for producing a polyester resin molded body according to the present invention,
Polyethylene terephthalate, and a modified polyolefin graft-modified with an unsaturated polycarboxylic acid or an anhydride thereof, comprising a polyester resin composition having a graft modified polyolefin content of 1 to 15% by weight, and having a thickness of Within the range of 0.2 to 2.0 mm, the crystallinity is 10%
The following sheet is formed, and then the sheet is heat-molded to obtain a molded body, and the molded body obtained is maintained at a temperature of 140 to 190 ° C. for 3 to 30 seconds so that the crystallinity of the molded body is 20. It is characterized by making it more than%.

A molded product obtained by using a polyester resin composition in which a specific amount of the specific modified polyolefin as described above is blended with a polyester resin, the modified polyolefin acts as an impact strength improver, and thus the impact strength is significantly improved. . Furthermore, since this modified polyolefin also acts as a crystallization accelerator, addition of the modified polyolefin accelerates the crystallization rate of the polyester resin,
The crystallization rate can be easily controlled by adjusting the addition amount of the modified polyolefin.

DETAILED DESCRIPTION OF THE INVENTION The method for producing a polyester resin molded product according to the present invention will be specifically described below.

The polyester resin composition used in the present invention, polyethylene terephthalate as a polyester resin,
Including modified polyolefin.

The polyethylene resin used in the present invention is polyethylene terephthalate composed of a repeating unit derived from terephthalic acid which is a dicarboxylic acid and a repeating unit derived from ethylene glycol which is a dihydroxy compound.

In the present invention, of the repeating units derived from the dicarboxylic acid constituting the polyethylene terephthalate which is the polyester resin, it is preferable that 50 mol% or more is the repeating units derived from terephthalic acid, and further 80
It is particularly preferable that the mol% or more is a repeating unit derived from terephthalic acid.

When the polyethylene terephthalate, which is the polyester resin, contains a dicarboxylic acid repeating unit other than a repeating unit derived from terephthalic acid, examples of preferred dicarboxylic acid repeating units include isophthalic acid and diphenyl ether-4,4-dicarboxylic acid. , Naphthalene
Aromatic dicarboxylic acids such as 1,4-dicarboxylic acid and naphthalene-2,6-dicarboxylic acid, aliphatic carboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid and undecadicarboxylic acid, hexahydroterephthalic acid, etc. The repeating unit derived from the alicyclic dicarboxylic acid and the like can be mentioned.

In the present invention, of the repeating units derived from the dihydroxy compound constituting the polyethylene terephthalate, which is a polyester resin, preferably 50 mol% or more is a repeating unit derived from ethylene glycol, and further 80 mol% or more is ethylene. Particularly preferred are repeating units derived from glycol.

When the polyethylene terephthalator contains a dihydroxy compound repeating unit other than a repeating unit derived from ethylene glycol, examples of the preferred dihydroxy compound repeating unit include fats such as propylene glycol, 1,4-butanediol and neopentyl glycol. Examples thereof include repeating units derived from group glycols, alicyclic glycols such as cyclohexanedimethanol, aromatic dihydroxy compounds such as bisphenol A, and the like.

In the present invention, as the polyethylene terephthalate, polyethylene terephthalate composed of a repeating unit derived from terephthalic acid and an ethylene glycol repeating unit is used. Further, the polyethylene terephthalate may be a copolymer, or may be a polyethylene terephthalate. It may be a mixture with other polyesters.

The molecular weight of polyethylene terephthalate used in the present invention is not particularly limited, but the intrinsic viscosity [η] of polyethylene terephthalate measured in o-chlorophenol at 25 ° C. is usually 0.6 dl / g or more, preferably 0.8 to 1.2d
Within the l / g range.

The modified polyolefin used in the present invention is a polyolefin graft-modified with an unsaturated polycarboxylic acid or an anhydride thereof (hereinafter sometimes simply referred to as “graft monomer”).

In the present invention, the unsaturated polycarboxylic acid used for modification of the polyolefin is a compound having a group having a graft-polymerizable unsaturated bond and a group consisting of a plurality of carboxylic acids or an anhydride of a plurality of carboxylic acids, Specific examples of such unsaturated polycarboxylic acid include maleic acid, maleic anhydride, itaconic acid and itaconic anhydride. The above grafting monomers can be used alone or in combination.

Examples of the polyolefin modified with such a graft monomer include homopolymers such as ethylene, propylene, butene, and 4-methylpentene, copolymers of these monomers, and hexene, octene and Examples thereof include a copolymer with an α-olefin having 6 or more carbon atoms such as decene. When the polyolefin is a copolymer, it may be a secondary copolymer or a three-dimensional or higher-dimensional copolymer.

Further, the modified polyolefin may be used in combination of two or more kinds.

As such a polyolefin, for example, when polyethylene is used, a melt flow rate at 190 ° C. of 0.02 g / 10 minutes or more polyethylene or a polyethylene copolymer is preferable, and when polypropylene is used, 23
Polypropylene or polypropylene copolymer having a melt flow rate at 0 ° C. of 0.05 g / 10 minutes or more is preferable.

There is no particular limitation on the method of grafting the above-mentioned polyolefin with the graft monomer, and a method usually employed for modifying the polyolefin can be used.
For example, a method in which a polyolefin, a graft monomer and a catalyst are mixed and melted to react, or a method in which the polyolefin is suspended or dissolved in a suitable solvent and the graft monomer and the catalyst are added to this suspension or solution to react Method etc. can be used.

In the present invention, the graft ratio of the above graft monomer in the modified polyolefin is preferably in the range of 10 ^{−4 to} 3% by weight, preferably 0.05 to 1% by weight.

The method for adjusting the grafting ratio of the modified polyolefin within the above range is to dilute the modified polyolefin graft-modified to a high concentration with the unmodified polyolefin to the above grafting ratio, or the grafting ratio within the above range. It is possible to employ a method such as a method of adjusting the blending amount of the grafting monomer so as to perform grafting.

The polyester resin composition used in the present invention requires that the content of the modified polyolefin in the polyester resin composition is within a specific range, and the content of the modified polyolefin in the polyester resin composition of the present invention is , 1 to 15% by weight.

That is, the modified polyolefin contained in the polyester resin composition of the present invention acts as an impact resistance improver and a crystallization accelerator in the polyester resin molded product of the present invention. Therefore, by setting the content of the modified polyolefin in the polyester resin composition within the range of 1 to 15% by weight, the impact resistance of the obtained molded article, particularly the impact resistance at low temperature, is greatly improved. At the same time, the crystallization speed is significantly improved. Further, by setting the content of the modified polyolefin within the above range, the excellent properties of the polyester resin can be effectively utilized. In particular, in the present invention, the content of the modified polyolefin in the polyester resin composition is 2
It is preferably in the range of up to 10% by weight.

The polyester resin composition of the present invention can also be produced by adding a modified polyolefin during the production of polyethylene terephthalate, or can be produced by mixing polyethylene terephthalate and a modified polyolefin according to a usual method and kneading. . Further, a polyester resin composition can be produced while mixing polyethylene terephthalate and a modified polyolefin, and the composition can be extruded into a sheet at once.

In the present invention, polyethylene terephthalate is preferably used after drying.

In the present invention, when a polyester resin composition is prepared by mixing polyethylene terephthalate and a modified polyolefin, when a modified polyolefin having a lower melting point than the drying temperature (140 to 160 ° C.) of polyethylene terephthalate is used, the drying is performed. The obtained polyethylene terephthalate is cooled once, or dry high temperature polyethylene terephthalate is put into an extruder under heat insulation and mixed with a modified polyolefin. A method of preparing a crude mixture (MB) of the above and adjusting the melting point of the modified polyolefin, blending this MB with dry polyethylene terephthalate, and a method of mixing the above MB with polyethylene terephthalate and then drying are adopted. Door can be.

The polyester resin composition used in the present invention contains heat-resistant stabilizers, weather-resistant stabilizers, antistatic agents, lubricants, lubricants, dispersants, pigments, and other additives commonly used in polyester resins. You can also do it.

To produce the polyester resin molded product of the present invention, first, a polyester resin containing the above polyethylene terephthalate and a graft-modified polyolefin, and optionally other components, and the content of the graft-modified polyolefin is 1 to 15% by weight. It consists of a composition and has a thickness of 0.
A sheet having a crystallinity of 10% or less is formed within a range of 2 to 2.0 mm.

 Next, the sheet is heat-molded to form a molded body.

Then, the obtained molded body is heated at a temperature of 140 to 190 ° C for 3 to 30
The polyester resin molded product of the present invention can be produced by maintaining the crystallinity of the molded product for 20 seconds or more by maintaining it for a second. As described above, particularly in the present invention, a sheet-like material (in the present invention, without being particularly limited, a sheet and a film include both a sheet and a film) is prepared using the above polyester resin composition. Can be manufactured by thermoforming this sheet.

Hereinafter, the method for producing the polyester resin molded article of the present invention will be described in detail along with the steps.

First, the sheet-like material used for producing such a polyester resin molded body may be a single layer, but 2
Different layers or more or the same layer may be laminated.

That is, the sheet-like material of the present invention comprises, for example, a polyethylene terephthalate layer containing the above modified polyolefin, a dicarboxylic acid such as terephthalic acid or isophthalic acid, and a hydroxy compound such as bis (2-hydroxyethoxy) benzene. Multi-layer sheet consisting of polyester layer, polyethylene terephthalate layer containing modified polyolefin, copolyester composed of dicarboxylic acid such as terephthalic acid or isophthalic acid and hydroxy compound such as bis (2-hydroxyethoxy) benzene, and polyethylene terephthalate It may be a multi-layer sheet formed by a layer composed of. Further, a sheet made of a resin such as polyolefin may be laminated on the above single layer sheet or multilayer sheet. Such a multilayer sheet is
For example, it can be manufactured by providing a passage of a plurality of nodes in a die and combining it with a plurality of extruders for coextrusion.

The thickness of the sheet thus obtained can be appropriately set in consideration of the use of the molded product, etc., but is usually in the range of 0.2 to 2.0 mm, preferably 0.3 to 1.0 mm.
Within the range. Such sheets have a very low degree of crystallinity, typically less than 10% and are substantially amorphous.

In the method for producing a polyester resin molded article of the present invention, for example, the sheet-like article produced as described above is heated so that the temperature of its surface is 100 to 170 ° C., and is drawn down to some extent, then, The draw-down sheet-like material is set in a mold heated to 140 to 190 ° C, and the air between the draw-down sheet-like material and the mold is vacuum degassed to shape the material. A sheet-like material is pressed against a mold by using air, or is shaped by a method of combining the above-mentioned vacuum deaeration and pressurized air. The polyester resin molded product of the present invention can be manufactured by pressing the product while hot.

In particular, in the present invention, the temperature of the molded product shaped by heat molding is set within the range of 140 to 190 ° C.
Hold for ~ 30 seconds. By carrying out the heat molding in this manner, a molded product having a high crystallinity can be produced from a sheet material having a low crystallinity.

The shape of the formed body obtained as described above is not particularly limited, and may be a desired shape such as a toilet shape, a cup shape, or a bottle shape.

During such thermoforming, the modified polyolefin acts as a crystallization accelerator, the crystallization rate of polyethylene terephthalate is improved, the semi-crystallization time is significantly shortened, and the crystallinity of the molded body is increased. It becomes 20% or more, and the gas barrier property and heat resistance are improved. further,
Since the modified polyolefin acts as an impact resistance improver, the impact resistance is improved.

Therefore, the molded product of the present invention can be suitably used as a molded product such as a container requiring high impact strength, particularly high impact strength at low temperature, and also suitable as a molded product for use requiring gas barrier properties. Can be used for. Further, since the heat resistance is improved as the crystallinity is improved, the molded product of the present invention can be used as, for example, a container for a microwave oven or an electric oven.

EFFECTS OF THE INVENTION Polyethylene terephthalate is obtained by further maintaining a molded body obtained by heat-molding a polyester resin composition containing a specific amount of the specific modified polyolefin as described above at 140 to 190 ° C. for 3 to 30 seconds. In the body, the modified polyolefin acts as an impact strength improver, so that the impact strength of the molded body is greatly improved. Furthermore, since the modified polyolefin acts as a crystallization accelerator, the crystallization rate of the molded article is increased, and the crystallization rate can be easily controlled by adjusting the addition amount of the modified polyolefin.

Furthermore, after heat-molding a sheet-like material prepared using this polyester resin composition into a desired shape, the obtained molded body is further maintained at 140 to 190 ° C. for 3 to 30 seconds to obtain a crystallinity of 20%. By the above, a crystalline polyester resin molded product having the above-mentioned excellent properties can be easily manufactured.

Next, the present invention will be described with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these Examples and the like.

Example 1 The intrinsic viscosity measured in o-chlorophenol at 25 ° C. is 0.
95 polyethylene terephthalate was dried at 150 ° C. under reduced pressure overnight.

In this polyethylene terephthalate, 100 mol% of the dicarboxylic acid repeating unit is a repeating unit derived from terephthalic acid, and 97 mol% of the glycol repeating unit is a repeating unit derived from ethylene glycol.

Separately, MFR (190 ° C) 0.3 g / 10 min, low density polyethylene with a density of 0.92 and maleic anhydride as a graft monomer were prepared, and the graft ratio of this graft monomer was 0.3.
The low-density polyethylene was modified so that the weight percentage would be.

A polyester resin composition was prepared by blending modified low-density polyethylene with polyethylene terephthalate so that the content of the modified low-density polyethylene was 3% by weight.

The obtained polyester resin composition was molded using an extrusion molding machine equipped with a casting roll having a screw diameter of 5 mm to obtain a 0.5 mm-thick non-crystalline sheet.

Then, using a vacuum forming machine (manufactured by Asano Laboratory Co., Ltd.), the obtained sheet is heated to 130 to 140 ° C.
A box-shaped container was manufactured by setting the temperature to 160 ° C. and holding it under a reduced pressure of 700 mmHg for 20 seconds to perform thermoforming and crystallization.

The obtained molded body was subjected to an impact test at -20 ° C using a film impact tester (manufactured by Toyo Seiki Co., Ltd.). Further, the half-crystallization time (t _1/2 ) was determined (measuring device: Perkin-Elmer Co., Ltd.). Here, the above-mentioned semi-crystallization time means that the sample is 120
The temperature is raised to ℃ in a short time (within 30 seconds), the sample is maintained at this temperature to promote crystallization, and the exothermic peak accompanying the increase in crystallinity is measured. Is the elapsed time to reach half.

 The results are as follows.

-Impact impact strength (-20 ° C) ... 450 kgcm / cm-Semi-crystallization time (t _1/2 ) ... 120 seconds In the examples and comparative examples shown below, impact impact strength (-20 ° C) and The half-crystallization time (t _1/2 ) was measured by the above method.

Comparative Example 1 A sheet was prepared in the same manner as in Example 1 except that unmodified polyethylene was used instead of modified polyethylene, and a molded body was produced using this sheet.

The impact impact strength and semi-crystallization time (t _1/2 ) of the obtained molded product are shown below: -Impact impact strength (-20 ° C) ... 300 kg-cm / cm-Semi-crystallization time (t _1/2 ) ... 140 seconds The impact impact strength of the molded body obtained in Example 1 is
It is higher than the impact impact strength of the molded body obtained in Comparative Example 1, and the half-crystallization time is also shortened by using the modified polyethylene.

Example 2 Instead of the modified polyolefin of Example 1, MFR (190
Modified polyethylene obtained by grafting 0.3% by weight of maleic anhydride to low-density polyethylene having a density of 0.92 and an ethylene / propylene random copolymer having an MFR (190 ° C) of 0.4 and a density of 0.87 (ethylene content 80%). Mol%) to 0.
A modified ethylene / propylene random copolymer grafted with 4% by weight of maleic anhydride was used, and the content of the modified low density polyolefin was 3% by weight and the content of the modified ethylene / propylene random copolymer was 2%. A polyester resin composition was prepared by mixing so as to have a weight percentage, and a sheet was prepared in the same manner except that this resin composition was used, and a molded body was produced using this.

The impact impact strength and the semi-crystallization time (t _1/2 ) of the obtained molded product are shown below: -Impact impact strength (-20 ° C) ... 700 kg-cm / cm-Semi-crystallization time (t _1/2 ) 125 seconds Comparative Example 2 A sheet was prepared in the same manner as in Example 2 except that unmodified polyethylene and unmodified ethylene / propylene random copolymer were used instead of modified polyethylene and modified ethylene / propylene random copolymer. Was prepared, and a molded body was manufactured using this.

The impact impact strength and the half-crystallization time (t _1/2 ) of the obtained molded product are shown below.

-Impact impact strength (-20 ° C) ... 400 kg-cm / cm-Semi-crystallization time (t1 _{/ 2} ) ... 145 seconds The impact impact strength of the molded body obtained in Example 2 is
It is higher than the impact impact strength of the molded body obtained in Comparative Example 2, and the half-crystallization time is also shortened by using the modified polyethylene.

Example 3 In Example 1, instead of the modified polyolefin,
A polyester resin composition was prepared by using a modified homotype propylene in which MFR (230 ° C.) 1.5 g / 10 minutes and density 0.91 was modified with 0.3% by weight of maleic anhydride, and this resin composition was used. Except for the above, a sheet was prepared in the same manner, and a molded body was produced using the sheet.

The impact impact strength and semi-crystallization time (t _1/2 ) of the obtained molded product are shown below: -Impact impact strength (-20 ° C) ... 400 kg-cm / cm-Semi-crystallization time (t _1/2 ) ... 125 seconds Comparative Example 3 In Example 1, instead of the modified polyolefin,
A sheet was prepared in the same manner except that 1% by weight of talc was used with respect to polyethylene terephthalate, and a molded body was produced using this sheet.

The impact impact strength and semi-crystallization time (t _1/2 ) of the obtained molded product are shown below: -Impact impact strength (-20 ° C) ... 300 kg-cm / cm-Semi-crystallization time (t _1/2 ) 145 seconds As described above, according to the present invention, the impact strength of the obtained molded article is improved. Further, the addition of the modified polyolefin increases the crystallization rate, and the crystallization rate can be controlled by adjusting the addition amount.

Claims (1)

(57) [Claims] 1. A polyester resin composition comprising polyethylene terephthalate and a modified polyolefin graft-modified with an unsaturated polycarboxylic acid or an anhydride thereof, wherein the content of the graft-modified polyolefin is 1 to 15% by weight. And a thickness within the range of 0.2 to 2.0 mm, and a crystallinity of 10% or less is formed into a sheet, and then the sheet is heat-formed into a formed body, and the obtained formed body is A method for producing a polyester resin molded product, which comprises maintaining the temperature of 190 ° C. for 3 to 30 seconds so that the crystallinity of the molded product is 20% or more.