JPH02255710A - Heat-resistant molded polymer product and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject molded product improved in heat resistance and dimensional stability by exposing a molded product consisting of a graft copolymer containing a polyester component as a backbone chain and a polyolefin component as branched chains to radiation and crosslinking the polyolefin component. CONSTITUTION:The objective molded product obtained by exposing a molded product consisting of a graft copolymer containing a polyester component (e.g. polyethylene terephthalate) as a backbone chain and a polyolefin component (e.g. polymethylene chain or polypropylene chain) as branched chains is exposed to radiation (preferably electron rays at 5-80Mrad irradiation dose) and at least partially crosslinking the polyolefin component.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyester polymer molded article with improved heat resistance and dimensional stability, and a method for producing the same.

(Prior art) Polyesters such as polyethylene terephthalate and polybutylene terephthalate, as well as various copolyesters based on these polyesters, have excellent physical and chemical properties, so they are often used as molded products such as fibers, films, and containers. It is used in the field of

However, in recent years, with the development of the electric/electronic equipment industry, the automobile industry, the aircraft industry, etc., there has been a demand for materials with better heat resistance and dimensional stability.

One of the effective means for improving the heat resistance and dimensional stability of polyester polymer molded articles is a method of crosslinking polyester, as described below.

■Isocyanate and epoxy on polyester.

A compound having a reactive group such as methylol is blended in advance, and these groups are reacted with the hydroxyl group or carboxyl group at the end of the polyester to cause crosslinking. ■An unsaturated group (double bond) is introduced into the molecule in advance, and the unsaturated group is subjected to bulk polymerization using heat, light, catalyst, radiation, etc. at any stage after molding. (Published by Kobunshi Publishing Association: “
Adhesion, Vol. 31, pp. 538-548, Vol. 32, pp. 11-20, Vol. 32, pp. 61-69.

Special Publication No. Sho 61-57850, Special Publication No. Sho 61-5785
Publication No. 1.

Special Publication No. 6i-57852, Special Publication No. 62-434
No. 59 Public II).

However, when the methods ① and ② above are adopted.

Thermoplastic polyesters that are useful as fibers and films and have high melting points (softening points) and crystallinity have the following problems.

That is, in the case of ■, generally isocyanate.

Compounds (crosslinking agents) with groups such as epoxy and methylol are added when polyester is melt-molded, but these groups are highly reactive, so when processing them into fibers, films, etc., the molding temperature is high. A cross-linking reaction occurs in the molding machine, resulting in gelation or difficulty in fluidizing, which significantly reduces molding processability. Polycondensation) is carried out at a high temperature of 250°C or higher, so addition polymerization of unsaturated groups occurs during this polycondensation stage, and in this case as well, it gels or becomes difficult to flow, making it difficult to form and process. Significantly reduce sexual performance.Also,
In both cases of ■ and ■.

It makes it difficult to stretch, which is an important step in the production of fibers and films.

In order to avoid such problems, it is possible to adopt a solution polycondensation method or a solution molding method that can be carried out at low temperatures, but problems such as complication of the process and increase in manufacturing costs arise.

(Problems to be Solved by the Invention) In reality, the method that utilizes intermolecular crosslinking as described above can only be applied to polyesters with low melting points, and is useful for polyesters that are useful as fibers, films, and other molded products. The reality is that it cannot be applied to polyesters with high melting points or high crystallinity.

Therefore, the main object of the present invention is to provide a high melting point or highly crystalline polyester polymer molded product with improved heat resistance and two-dimensional stability, and a method for easily producing the molded product. This is an issue to be addressed.

(Means for Solving the Problems) The present inventors have discovered that polyesters, especially polyesters with high melting points or high crystallinity, also have heat resistance.

Various studies were conducted to obtain a molded product with improved dimensional stability. As a result, when a molded article made of a graft copolymer having a polyester component as a main chain and a polyolefin component as a branched chain is irradiated with one radiation to crosslink at least a portion of the polyolefin component, the polyolefin component becomes polyester polycondensed. The present inventors have discovered that molded articles meeting the above objectives can be obtained with good productivity because they can withstand high temperatures during the process and are crosslinked relatively easily by radiation, leading to the present invention.

That is, the gist of the present invention is as follows.

(1) Consists of a graft copolymer with a polyester component as the main chain and a polyolefin component as a branched chain.

A heat-resistant polymer molded article characterized in that at least a portion of the polyolefin component is crosslinked.

(2) A molded article made of a graft copolymer having a polyester component as a main chain and a polyolefin component as a branched chain is irradiated with radiation to crosslink at least a portion of the polyolefin component. Method for manufacturing molecular molded products.

Hereinafter, one aspect of the present invention will be explained in detail.

In the present invention, the polyester of the "polyester component" means a thermoplastic polyester that can be melt-molded, and such polyesters include terephthalic acid, ymphthalic acid, adipic acid, and glutaric acid.

azelaic acid, sebacic acid, naphthalene dicarboxylic acid,
Dicarboxylic acid components such as cyclohexanedicarboxylic acid and diphenylsulfonedicarboxylic acid and ethylene glycol,
Diethylene glycol, polyethylene glycol, trimethylene glycol.

Propylene glycol, 1,4-butanediol, 1°5-bentanediol, 1,6-hexanediol.

Neopentyl glycol, xylylene glycol.

It is obtained from glycol components such as cyclohexane dimetatool, bis(β-hydroxyethoxyphenyl)propane, and bis(β-hydroxyethoxyphenyl)sulfone, and in addition to the above-mentioned dicarboxylic acid components and glycol components.

Hydroxycarboxylic acid components such as ε-hydroxycaproic acid, β-hydroxyethoxybenzoic acid, hydroxybenzoic acid, and in some cases trimellitic acid, trimesic acid,
It is obtained by appropriately combining components having three or more functional groups such as romellitic acid, trimethylolpropane, and pentaerythritol. Preferred specific polyesters include polyethylene terephthalate, polybutylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene-2゜6-naphthalate poly-p-ethyleneoxybenzoate, and polyesters containing these as main components. can be mentioned. These are polyesters with relatively high melting points and high crystallinity, and the purpose of the present invention is particularly useful. Needless to say,
The present invention is also applicable to polyesters with a relatively low melting point, for example, polyesters containing a large amount of fatty acid dicarboxylic acid components such as the above-mentioned adipic acid and sebacic acid.
It has a similar effect.

Polyolefin, which is a "polyolefin component," is a general term for polymers consisting of structural units represented by saturated hydrocarbon polymer chains, such as polymethylene chains and polypropylene chains. −
Refers to substances that have virtually no carbon double bonds or triple bonds,
Therefore, there is no problem even if some of them have a stable group such as a benzene ring or a naphthalene ring as a substituent. This polyolefin chain may be either linear or branched. The number of carbon atoms in the polyolefin chain is generally 5.
~200. Preferably it is 8-100.

The polymer constituting the molded article of the present invention is a graft copolymer having the above-mentioned polyester component as the main chain and the polyolefin component as a branched chain, and the polyolefin component is formed into an ester at any stage during the production of the polyester. It can be produced by adding a polyolefin having a specific functional group and copolymerizing it with a polyester.

Ester-forming functional groups in the polyolefin component include hydroxyl groups and carboxyl groups.

Examples include monofunctional groups such as alkoxycarbonyl groups and difunctional groups such as epoxy groups, and difunctional polyolefins are preferred.

The ratio of the polyester component to the polyolefin component is 99-70:1-30. More preferably 98~
A ratio of 80:2 to 20 is preferable in terms of moldability (processability) and crosslinking effect due to radiation irradiation.

The polymer molded article of the present invention only needs to have a structure in which at least a portion of the polyolefin component is crosslinked, and the polymer does not necessarily need to be crosslinked to an insoluble and infusible state so that the polymer has a network structure. In other words, if at least a portion of the polyolefin component of the polymer that makes up the film or fiber is crosslinked.

This is because the resulting molded product has improved heat resistance and dimensional stability.

The polymer molded article of the present invention can be easily produced by a method of irradiating a molded article made of a graft copolymer of a polyester component and a polyolefin component with radiation.

Examples of radiation include electron beams, alpha rays, gamma rays, etc., and electron beams are particularly preferably used.

The irradiation dose of these radiations is 3 to 100 Mrad.
.

Particularly preferred is 5 to 80 Mrad. If the irradiation dose is too large, the physical properties of the molded article may deteriorate, which is not preferable. Also, especially when using an electron beam.

Since the depth that the electron beam reaches increases linearly in proportion to the accelerating voltage, it is preferable to adjust the accelerating voltage according to the thickness and thickness of the molded product. The voltage is preferably between 10 and 10,000 KV, preferably between 50 and 5,000 KV. The temperature at the time of irradiation varies depending on the glass transition temperature of the polymer constituting the molded article, but is preferably carried out in the range from about 20° C. lower than the glass transition temperature to about 60° C. higher than the glass transition temperature. Practical temperatures are 30-150°C. The higher the temperature, the shorter the time required for irradiation, but if the temperature is too high, dimensional changes may occur in the molded product before crosslinking has sufficiently progressed, or crystallization may proceed too much, which is not preferable.

Irradiation can be performed in air, in an inert gas such as nitrogen or argon, or in vacuum, but it is practical to perform it in air.

(Example) The present invention will be explained in more detail below using two examples.

Examples 1 to 4 and Comparative Examples 1 to 5 1,2-tetradecanediol was first added to an oligomer (number average degree of polymerization of 5) of bis(β-hydroxyethyl) terephthalate obtained by esterifying terephthalic acid and ethylene glycol. The mixtures were blended in the proportions shown in the table, and 2XIO-' mol of antimony trioxide dissolved in ethylene glycol was added per 1 mol of the terephthalic acid component, and the mixture was charged into a batch reactor for polyester polycondensation. Next, while maintaining the internal temperature at 275 ° C., at normal pressure for 0.5 hours, and while reducing the pressure from normal pressure to a maximum vacuum of 0.1 Torr, for 0.5 hours,
Furthermore, a polycondensation reaction was carried out for 3 hours under this maximum reduced pressure.

The almost white polyester chips obtained were fed to an extruder-type melt extruder and heated to lip rj+ at 280°C.
It was extruded from a T die of 200 mm, lip spacing Q, and 3 ni, and the extruded molten film was cooled and solidified using a casting roller kept at 20° C. to obtain an unstretched film. Next, using a tenter-type simultaneous biaxial stretching device, 95
Stretched 3.1 times lengthwise and horizontally at ℃, then further stretched at 235℃
After heat treatment with a relaxation rate of 3% both lengthwise and horizontally, it was trimmed and wound at a speed of 20m/min to a thickness of lOIIm.
+ A stretched film with a width of 300 mm was obtained.

There were no cutting problems in these film forming and stretching operations, and the operability was good. Moreover, the stretched film showed good appearance.

Next, the obtained stretched film was irradiated at a temperature of 120°C.
It was irradiated with an electron beam with an accelerating voltage of 750 KV (absorbed dose per second was I Mrad). Table 1 shows the relationship between the irradiation dose and the dry heat shrinkage rate in the longitudinal direction of the film (processed at 160° C. for 15 minutes). Note that 9 samples other than those regulated by the present invention were used as comparative examples.

As is clear from Table 1, the molded articles of the present invention have a low dry heat shrinkage rate and are excellent in heat resistance and dimensional stability.

(Effects of the Invention) According to the present invention, a polyester polymer molded article having excellent heat resistance and good one-dimensional stability is provided.

Furthermore, according to the method of the present invention, the above-mentioned molded product can be easily obtained with good productivity.

Claims (2)

[Claims] (1) A heat-resistant polymer molded article comprising a graft copolymer having a polyester component as a main chain and a polyolefin component as a branched chain, wherein at least a portion of the polyolefin component is crosslinked. (2) A molded product made of a graft copolymer with a polyester component as the main chain and a polyolefin component as a branch chain,
A method for producing a heat-resistant polymer molded article, which comprises crosslinking at least a portion of a polyolefin component by irradiating it with radiation.