JP2007031636A - Polyester-based resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester-based resin which can be used for molding a comparatively thick product and has shape retaining property and flexibility. <P>SOLUTION: The polyester-based resin composed of a polyolefin islands floating in a sea of a polyester is produced by mixing a softener for a polyester resin with a polyester-based resin composed of at least 3 components of a polyester, a polyolefin and a polyfunctionally modified vinyl polymer, followed by extrusion molding and then stretching up to 1.05-2.5 folds. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyester resin.

  The polyester resin is a polymer having an ester bond in the main chain. Polyethylene terephthalate (PET) is a representative example and is used in the largest amount. Since this polyester is excellent in various physical properties, it is currently used in various ways.

  However, this polyester generally has a low melt viscosity, and it has been difficult to mold a thick product. In other words, if the melt viscosity is low, a draw-down phenomenon occurs in which the melt hangs down from the die of the extrusion molding machine or the parison of the blow molding machine by its own weight, so that high-precision molding is difficult.

  For this reason, it is considered to improve the moldability by increasing the melt viscosity. For example, a modifier or a polymerizing agent having a thickening effect may be added. The modifier itself has a high viscosity and is mixed with polyester to increase the viscosity as a whole. For example, polyethylene, polypropylene, styrene-ethylene-butadiene copolymer, acrylic rubber and the like. There is also an example in which the melt tension is improved by fibrillating itself and having a fibrous network structure without melting itself.

  Further, as the polymerizing agent, a polymer modifier having a functional group capable of reacting with polyester or a polyfunctional acid anhydride represented by pyromellitic acid is used. This is to increase the viscosity by reacting with the alcohol group or carboxylic acid group of the polyester to form a polymer.

However, satisfactory results are not obtained with any conventional method.
Further, apart from this, there has been a demand for a metal substitute or one that can be freely changed in shape by giving the plastic itself shape retention.
There is no such thing in the past, and like a soft metal, the shape can be freely changed and there is no way to keep the shape.

  Accordingly, a polyester resin that can be molded even with a relatively thick thickness and has shape retention and flexibility is provided.

  In view of the above situation, the present inventor has completed the polyester resin of the present invention as a result of intensive studies, and is characterized by at least 3 of polyester, polyolefin, and polyfunctional modified vinyl polymer. A composition in which a polyester resin softener is mixed into a polyester resin having components, extruded, then stretched by 1.05 to 2.5 times, and a polyolefin island exists in the polyester sea It is in the point.

Here, the polyester is not only polyethylene terephthalate, but also polybutylene terephthalate (PBT), 1,4-cyclohexyldimethylene terephthalate (PCT), polyethylene naphthalate (PEN), polylactic acid, and other biodegradable polyesters. Furthermore, there are other aliphatic polyesters, aromatic polyesters and derivatives thereof, and in other words, what is necessary is just to have an ester bond in the main chain.
Moreover, the collect | recovered PET resin and the commercially available thing may be used.
A mixture of a plurality of the above may be used.

The polyolefin is typically polyethylene or polypropylene, but may be polybutadiene or methylpentene resin. In our experiments, polyethylene, also low density polyethylene, was preferred. A plurality of these may also be used.
The mixing amount of the polyolefin is preferably 1 to 30 parts by weight, and more preferably 1 to 8 parts by weight with respect to 100 parts by weight of the polyester. This is to provide an island structure for the polyester sea.

The polyfunctional modified vinyl polymer has a polyolefin portion and a functional group portion, and an elastomer is preferable. The functional group should just react with the carboxylic acid and alcohol of polyester. For example, acid anhydrides, carboxylic acids, alcohols, esters, salts, and the like.
Examples of the compound include maleic anhydride-containing styrene plastic elastomer, acid-modified saturated styrene thermoplastic elastomer, styrene-butadiene copolymer hydrogenated organic acid derivative adduct, and the like.
It suffices to have at least one functional group, and not two or more functional groups. This is because the purpose is different from that of a so-called crosslinking agent.

The mixing amount of the polyfunctional modified vinyl polymer is preferably 1 to 30 parts by weight, and more preferably 1 to 8 parts by weight with respect to 100 parts by weight of the polyester.
The viscosity can be freely adjusted by this amount.

Furthermore, in this invention, the softening agent for polyester resins is mixed here.
The softening agent for a polyester resin improves the flexibility when mixed with a polyester resin. In particular, not only those that are commercially available as softening agents, but also those that exhibit such properties. Examples thereof include plasticizers for vinyl chloride such as adipic acid derivatives, ethylene glycol derivatives, glycerin derivatives, vegetable oils, silicon compound derivatives (silicon powder, etc.), phthalate esters, and the like.
The mixing amount of the softening agent for polyester resin is preferably about 0.5 to 30 parts by weight with respect to 100 parts by weight of polyester.

  Furthermore, you may mix inorganic type microparticles | fine-particles with this invention polyester resin. Examples thereof include talc, charcoal cal, and silicon oxide ultrafine particles. Talc is an oxide of magnesium and silicon having crystal water. Moreover, although these magnitude | sizes are not specifically limited, tens of micrometers-several nm are suitable. These can be crystal nucleating agents, and the addition of this promotes crystallization and is considered to increase the heat-resistant temperature. The mixing amount is preferably 1 to 8 parts by weight with respect to 100 parts by weight of the polyester.

  Moreover, a part or all of this general inorganic fine particle (filler) can also be changed to a nanofiller. The nano filler is a fine powder having a size of 5 to 100 nm, and Aerosil (manufactured by Nippon Aerosil Co., Ltd.) is commercially available. Of course, other fine particles may be used.

In the present invention, an additive may be further added to the above-described components. For example, pigments, fragrances, ultraviolet absorbers, fillers and the like. Furthermore, it is also preferable to add an inorganic filler whose surface is treated with a polymerizing agent having a functional group that reacts with polyester.
In short, anything may be added as long as it is not contrary to the gist of the present invention.

In the present invention, the material as described above is extruded and further stretched. Extrusion may be a normal method and need not be a special method. A normal apparatus may be used under normal conditions. That is, the extrusion temperature, speed, thickness, etc. are also free. However, the thickness is preferably about 0.5 mm to 3 mm.
Moreover, although this is extended | stretched, the direction of extending | stretching may be a longitudinal direction or the perpendicular direction. Of course, other angles may be used.

  As a draw ratio, it is about 1.05-2.5 times. In particular, about 1.05 to 1.5 times was suitable. When stretching in the longitudinal direction, it may be held and pulled with a normal pinch roll. To stretch in the direction substantially perpendicular to the extrusion direction, a TD direction stretching device may be used. Alternatively, the sheet may be pulled after being cut into a predetermined length to form a sheet. Moreover, you may extend | stretch in directions other than one direction. That is, it is a biaxial stretching type. Also at this time, the draw ratio is 1.05 to 2.5 times as described above.

  The material of the present invention is also characterized in that a polyolefin island is present in the polyester sea. Instead of simply mixing, it is necessary to have such a structure. This can be achieved with the aforementioned mixing ratio. Further, the polyfunctional modified vinyl polymer seems to be covered like an egg shell around the polyolefin in the island state.

  When such a material is extruded, the island portion becomes an ellipse of about 1: 3 to 10 extending long in the extrusion direction. Further, when this is stretched in a direction substantially perpendicular to the extrusion direction, many cracks are formed in the stretch direction in the sea portion. It is thought that shape retention is born by the presence of these many cracks.

  In addition, the large number of cracks stop at the island and no further cracks extend. It is considered that the strength (breaking strength) is secured by preventing the extension of the cracks. In particular, it is considered that cracks are more reliably stopped by the polyfunctional modified vinyl polymer that is considered to exist around the island.

  As an application of the present invention, it can be used for a part that requires shape retention, a part that requires flexibility, and various other applications, and can be used for a metal substitute part and any other object. For example, there are a fastener for binding a document, a twisted string, and the like.

The polyester resin of the present invention has the following great advantages.
(1) Polyester, which was difficult to mold due to low viscosity, had high viscosity and good moldability. In particular, in the case of PET, the wall thickness is conventionally up to about 0.8 mm, but more than that is now possible.
(2) Foam molding, which has been difficult in the past, has become possible by increasing the viscosity.
(3) It is considered that direct blow molding, which has been difficult in the past, becomes possible by increasing the viscosity.
(4) In terms of physical properties, heat resistance is improved and impact resistance is expected to be improved.
(5) It becomes very flexible and stretched by stretching. The bent feeling is like a soft clay that bends easily and maintains its state. I don't think it's very plastic.
(6) It is excellent in tensile strength and can be used normally as a plastic molded product.

Hereinafter, based on an Example, this invention is demonstrated in detail.
First, each component was mixed to prepare Composition Examples 1 to 12 and Comparative Compositions 1 to 3.
Each component used the following.
Polyester resin: “Polylactic acid H-440” manufactured by Mitsui Chemicals, Inc.
Polyolefin: “Low-density polyethylene resin, Ultozex 3010F (trademark)” manufactured by Mitsui Chemicals, Inc.
Multifunctional modified vinyl polymer: “Acid-modified saturated styrenic thermoplastic elastomer, Tuftec M1913 (trademark)” manufactured by Asahi Kasei Corporation
Softener:
A: Dioctyl adipate (DOA): “DOA” manufactured by Daihachi Chemical Industry Co., Ltd.
B: Diisodecyl adipate (DIDA): “DIDA” manufactured by Daihachi Chemical Industry Co., Ltd.
C: Dioctyl phthalate (DOP): “DOP” manufactured by J Plus
D: Glyceryl triacetate: “Triacetin” manufactured by Daihachi Chemical Industry Co., Ltd.
E: Polyoxyethylene benzoate: “Rikaflow LA-100” manufactured by Shin Nippon Chemical Co., Ltd.
F: Rapeseed soybean mixed oil: “Salad oil” manufactured by Nisshin Oilio

These mixing ratios are shown in Table 1. Numerical values are parts by weight.

It molded using the composition example shown in Table 1, and a comparative composition, and shape | molded into the atypical flat plate and the sheet | seat. And we examined flexibility and shape retention. The results are shown in Table 2.
In Table 2, ◯ of flexibility indicates sufficiently soft and X indicates hard. ○ in shape retention (shape retention) keeps the bent state almost as it is,-indicates that the return is severe.
Further, MD in the stretching direction indicates the same direction as the extrusion direction, and TD indicates a direction substantially perpendicular to the extrusion direction.

From the examples in Table 2, it can be seen that the present invention is excellent in flexibility and shape retention.
Further, it can be seen from Comparative Example 1 that even if the components are the same, there is no effect unless they are stretched. From Comparative Examples 2 and 3, it is also clear that those having no softening agent such as Comparative Composition 1 have no effect. From Comparative Example 4, it was found that there was no effect even if the amount of polyolefin was too large.

Claims (3)

A polyester resin having at least three components of polyester, polyolefin, and polyfunctional modified vinyl polymer is mixed with a softener for polyester resin, extruded, and then stretched by 1.05 to 2.5 times. A polyester resin characterized in that a polyolefin island exists in the sea. The polyester resin according to claim 1, wherein 1 to 30 parts by weight of polyolefin and 1 to 30 parts by weight of polyfunctional modified vinyl polymer are mixed with 100 parts by weight of polyester. The polyester resin according to claim 2, wherein 1 to 8 parts by weight of inorganic fine particles are mixed with 100 parts by weight of polyester.