JPH0826139B2 - Method for producing polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a polyester. More specifically, the present invention relates to a method for producing a polyester having a small decrease in softening point by adding a specific phosphorus compound, and having excellent hydrolysis resistance and flame retardancy. More specifically, it relates to a method for producing a polyester suitable as a flame-retardant polyester fiber, a film, and other molded articles.

[Prior Art] Polyester typified by polyethylene terephthalate has excellent physical and chemical properties and is used as a fiber, a film, and other molded articles. In particular, it is widely used in close contact with everyday life such as clothes, bedding, curtains, and jutan for fibers, and magnetic tapes, capacitors, and home appliances and electronic devices other than photography for films.

On the other hand, polyester is generally flammable, and it has been desired to impart flame retardancy to various processed polyester products from the viewpoint of fire prevention.

Conventional methods for imparting flame retardancy to polyester include (1) a method of chemically or physically adhering or impregnating the surface or inside of a molded article (post-processing method), (2) a flame retardant during molding Various methods such as a method of kneading (blending method), (3) a method of adding and copolymerizing a flame retardant at the time of polyester production (copolymerization method) have been proposed. Among these methods, (3) has a high industrial value without defects such as seepage of the modifier in the manufacturing process. Halogen compounds and phosphorus compounds are known as flame retardants capable of imparting flame retardancy by copolymerization, but phosphorus compounds are superior in terms of light resistance and coloring. Therefore, many methods of introducing a phosphorus compound into the polyester main chain for the purpose of imparting flame retardancy have been proposed. For example, Japanese Patent Publication Sho 49-22958
The publication discloses that a phosphoric acid ester is copolymerized with a polyester as a phosphorus compound, but a large amount of diethylene glycol is produced as a by-product during polyester production by blending the phosphorus compound to an amount that imparts flame retardancy to the polyester. However, there are drawbacks such that the characteristics of the polyester are remarkably deteriorated, the hydrolysis resistance of the polyester is lowered, and the molecular weight is lowered during molding. In JP-A-59-91122, phosphonic acid is used as the phosphorus compound, but the phosphorus compound is often scattered during the polyester manufacturing process.

Further, JP-B-36-20771, JP-B-53-13479, and JP-A-52-142796 disclose phosphorus compounds having a special ester-forming functional group. However, it is expensive because the synthesis is complicated and the purification is difficult, and it is industrially disadvantageous.

[Problems to be Solved by the Invention] An object of the present invention is to propose a method for producing a polyester by adding a specific phosphorus compound in order to solve the above-mentioned drawbacks of the prior art. It is possible to obtain a phosphorus-containing polyester which is excellent in hydrolysis resistance and flame retardancy, in which point reduction and scattering of phosphorus compounds are small.

[Means for Solving Problems] The above-mentioned object of the present invention is to produce a polyester by the reaction of dicarboxylic acid or its ester-forming derivative with ethylene glycol, and the phosphorus atom content in the polyester is 0.05 to 2.0% by weight. This can be achieved by a method for producing a polyester, which is characterized in that a phosphorus compound represented by the following formula is added so that the content becomes 10%.

The polyester of the present invention is produced by transesterification or esterification reaction of dicarboxylic acid or its ester derivative with ethylene glycol, and polycondensation reaction. The type of polyester is not particularly limited as long as it can be molded into a fiber, a film, or other molded products. Suitable polyesters that can be molded into fibers, films and other molded articles are those in which the dicarboxylic acid component is an aromatic dicarboxylic acid, such as polyethylene terephthalate, polyethylene-p-oxybenzoate, polyethylene-1,2- Bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate, polyethylene-1,2-bis (phenoxy) ethane-4,4'-
Examples thereof include dicarboxylate and polyethylene-2,6-naphthalene dicarboxylate. Among them, polyethylene terephthalate is preferable. Of course, these polyesters may be homopolyesters or copolyesters, and as the components to be copolymerized, for example, diethylene glycol, neopentyl glycol, polyalkylene glycol having an average molecular weight of 150 to 20000, p-xylylene glycol, 1,4-cyclohexanedimethanol, diol component such as 5-sodium sulforesorcin, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, dicarboxylic acid component such as 5-sodium sulfoisophthalic acid, Examples thereof include polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid.

Examples of the phosphorus compound in the present invention include, for example, tris (hydroxymethyl) phosphine oxide, tris (hydroxypropyl) phosphine oxide, tris (hydroxyoctyl) phosphine oxide and their tris (hydroxyalkyl) phosphine oxide derivatives, Tris (methoxypropyl) phosphine oxide, tris (ethoxybutyl) phosphine oxide and their tris (alkoxyalkyl) phosphine oxide derivatives, tris (carboxypropyl) phosphine oxide, tris (carboxyoctyl) phosphine oxide and their tris (carboxyalkyl) ) Phosphine oxide derivatives or alkylenes of tris (hydroxyalkyl) phosphine oxide derivatives Or the like can be mentioned Kisaido adduct.

The phosphorus compound of the present invention is added during the production of the polyester, but the phosphorus atom content in the obtained polyester is 0.
It is added so that it becomes 05 to 2.0% by weight. Preferably 0.0
7 to 1.5% by weight, more preferably 0.1 to 1.0% by weight
Is. When the addition amount of the phosphorus compound is less than this range, the flame retardancy of the molded article such as fiber and film is poor, and conversely when the addition amount of the phosphorus compound is more than the above range, the physical properties of the polyester obtained are deteriorated. It is not preferable because it becomes extremely large. Regarding the method of adding the phosphorus compound in the production process of polyester, it can be added at any stage of the production process of polyester, during the esterification or transesterification reaction, it may be any of the polycondensation reaction, preferably It is between the end of the esterification or transesterification reaction and the beginning of the polycondensation reaction. It is also a preferable method to add the phosphorus compound after mixing, dissolving or heat-condensing with a diol component such as ethylene glycol or another solvent in advance.

Further, the polyester of the present invention is sodium, lithium, calcium, magnesium, manganese, zinc, kovaruo, antimony, germanium, which are usually used in production.
Metal compound catalyst such as titanium, anti-coloring agent, antioxidant,
Pigments, fluorescent whitening agents, surfactants, antistatic agents, and further inorganic particles such as silica, calcium carbonate, titanium dioxide, aluminum oxide, talc, clay and calcium phosphate can be appropriately added if necessary.

When various molded articles are produced from the phosphorus atom-containing polyester of the present invention, the polyester may be used alone, or may be appropriately blended with another polyester for use.

In the case of producing a film from the phosphorus atom-containing polyester of the present invention, the polyester is molded into a sheet by a usual method and stretched in at least one direction.
It is manufactured by heat setting at a temperature of 0 ° C or higher.

[Examples] The present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

 The characteristics in the examples were measured as follows.

A. Intrinsic viscosity of polymer Measured at 25 ° C using o-chlorophenol as a solvent.

B. Polymer softening point Put polymer chips in a heating bath and heat at 6 ℃ / 5 minutes,
The temperature at which the tip of the load penetrates into the chip by 5 mm or more was measured.

C. Phosphorus content It was measured by a colorimetric method.

D. Hydrolysis resistance of polymer As a measure of hydrolysis resistance of polymer chips, the change in polymer intrinsic viscosity when polymer chips were vacuum-dried at 180 ° C. for 3 hours was used.

Decrease in intrinsic viscosity of polymer = Intrinsic viscosity of polymer before drying-Intrinsic viscosity of polymer after drying ◎: Intrinsic viscosity decrease of 0.02 or less (particularly preferred within the scope of the present invention) ○: Intrinsic viscosity decrease of more than 0.02 , 0.05 or less (within the object range of the present invention) Δ: Intrinsic viscosity decrease exceeds 0.05 and 0.10 or less (does not reach the object of the present invention) ×: Intrinsic viscosity decrease exceeds 0.10 (It does not reach the object of the present invention.) E. Flame retardancy of film UL94-HB was determined by the horizontal flame test method of UL94 flame retardancy test standard for plastic materials issued by Underwriter Laboratories.

⊚: Burning rate is 1.5 inches / min or less (particularly preferable within the object range of the present invention) ◯: Burning rate is 2.5 inches / min or less to over 1.5 inches (preferable within the object range of the present invention) Δ : Burning rate of 4.0 inches / min or less to over 2.5 inches (does not reach the object of the present invention) X: Burning rate exceeds 4.0 inches / min (does not reach the object of the present invention) Example 1 After transesterifying 100 parts by weight of dimethyl terephthalate and 70 parts by weight of ethylene glycol with 0.09 parts by weight of calcium acetate as a catalyst according to a conventional method, tris (hydroxypropyl) is added so that the phosphorus compound becomes 1.6% by weight (with respect to polymer). 20% by weight of phosphine oxide
The containing ethylene glycol solution was added and stirred for 5 minutes. Next, 0.03 parts by weight of antimony trioxide was added as a polymerization catalyst. Then, polycondensation reaction was carried out at a high temperature under reduced pressure according to a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity of 0.657, a softening point of 258.0 ° C. and a phosphorus content of 0.20%.

As a result of vacuum-drying the obtained polyester under the conditions of 180 ° C. for 3 hours, the intrinsic viscosity of the polymer was found to be as good as 0.014. Then, the dried polyester was melt-extruded into a film according to a conventional method to obtain a biaxially stretched film having a thickness of 75 μm.
The resulting film had good flame retardancy.

Comparative Example 1 The procedure of Example 1 was repeated except that the phosphorus compound was added in an amount of 0.3% by weight. The intrinsic viscosity was 0.655 and the softening point was 259.3.
C., polyethylene terephthalate having a phosphorus content of 0.04% was obtained.

Although the obtained polyester had good hydrolysis resistance, when a film was produced in the same manner as in Example 1 and flame retardancy was evaluated, it was poor.

Examples 2 to 6 and Comparative Examples 2 to 5 Polyethylene terephthalate shown in Table 1 was obtained in the same manner as in Example 1.

Examples 2 to 6 were within the scope of the present invention, and all polyesters had good properties, and phosphorus compounds were scarcely scattered. The films obtained from the polyester all had excellent flame retardancy.

On the other hand, in Comparative Example 2, the phosphorus atom content in the polyester is out of the range of the present invention, the softening point of the polyester is extremely lowered, or the hydrolysis resistance of the polyester is poor, resulting in low film strength. Had.

Further, Comparative Examples 3 to 5 use phosphorus compounds outside the scope of the present invention, and the softening point of the polyester is extremely lowered, or a large amount is used in order to make the phosphorus atom content in the polyester within the scope of the present invention. There are drawbacks such as the addition of a phosphorus compound or the poor hydrolysis resistance of any polyester, resulting in a decrease in film strength.

[Advantages of the Invention] In the present invention, by adding a specific phosphorus compound into the polyester reaction system as described above, there is no decrease in the softening point due to the by-product of diethylene glycol and scattering of the phosphorus compound, which has not been obtained conventionally. It is possible to obtain a phosphorus atom-containing polyester having a small amount and excellent polymer properties.

The polyester obtained by the production method of the present invention is of course a film, when producing fibers and other molded products, there is no deterioration of polymer physical properties in the molding processing step, and a molded product with excellent flame retardancy is manufactured. When the molded product is a film, it is preferably used as a member for electronic devices, home appliances and the like.

Claims (1)

[Claims] 1. A phosphorus compound represented by the following formula so that the phosphorus atom content in the polyester is 0.05 to 2.0% by weight when a polyester is produced by reacting a dicarboxylic acid or its ester-forming derivative with ethylene glycol. A method for producing a polyester, comprising adding [A, B: 1 to 1 carbon atoms not containing an ester-forming functional group
The 20 organic groups may be the same or different. R ₁ : ester-forming functional group n: 0 to 500]