JP4635508B2 - Modified polyester - Google Patents

Description

  The present invention relates to a method for producing a modified polyester obtained by copolymerizing an isophthalic acid component having a polyethylene glycol and a sulfonate group, and more specifically, excellent in color of a polymer, and further, an increase in filtration pressure during melt spinning. The present invention relates to a modified polyester composition capable of suppressing the above.

  Polyesters, especially polyesters based on polyethylene terephthalate, have excellent mechanical, mechanical and chemical properties, so that they are fibers for clothing, industrial use, films for magnetic tape, surface coating, etc., and tires. It is widely used for industrial purposes such as cords and nets, but it cannot be said that the dyeing property is necessarily good as a fiber for clothing, and since it is dyed with disperse dyes, only limited dyes can be used and dyed products Have the disadvantages of poor clarity.

  In order to compensate for these disadvantages, modified polyesters obtained by copolymerizing an isophthalic acid component having a sulfonate group represented by 5-sodium sulfoisophthalic acid (hereinafter referred to as SI component) are widely known (for example, patents). Reference 1). However, when melt spinning is carried out using polyester copolymerized with SI components, there has been a fundamental problem that the rate of increase in filtration pressure is large, heat resistance during melt spinning is poor, and stable production is difficult.

Various studies have been made so far in order to solve the above problems in modified polyesters mainly copolymerized with SI components (for example, Patent Document 2). There has been proposed a method for suppressing thermal degradation during melt spinning by limiting the amount and defining the material amount ratio between the lithium atom content and the SI component (for example, Patent Document 3). Although regulating the increase in filtration pressure by regulating the lithium atom content and the material amount ratio of the SI component, it has the disadvantage that the color tone of the resulting polymer tends to deteriorate. In addition, a method of defining the phosphorus atom content and including a hindered phenol compound has been proposed, but although the heat resistance is certainly improved, it has the disadvantage of a large increase in filtration pressure (for example, Patent Document 4). Moreover, although the method of prescribing | regulating the substance amount ratio of a lithium atom and SI component and the substance amount ratio of a lithium atom and a phosphorus atom is proposed, it was not enough at the point of suppression of a filtration pressure rise (for example, patent document 5). .
Japanese Patent Publication No.34-10497 Japanese Patent Laid-Open No. 11-5834 JP 2002-322247 A (first page, claim 1) JP 10-226923 discloses (page 1, claim 1) JP 58-138731 JP (page 1, claim 1)

  An object of the present invention is to produce a polymer color tone in the production of a modified polyester obtained by copolymerizing an isophthalic acid component having a polyethylene glycol and a sulfonate group using a direct heavy oligomer mainly composed of terephthalic acid and ethylene glycol. It is an object of the present invention to provide a modified polyester that is excellent in the above-described method, can suppress the increase in filtration pressure, and can be stably melt-spun.

A modified polyester obtained by copolymerizing an isophthalic acid component having a polyethylene glycol and a sulfonate group using a direct heavy oligomer mainly composed of terephthalic acid and ethylene glycol satisfies the following formulas 1, 2, and 3 simultaneously. It is to provide a modified polyester characterized in that.

0.01 ≦ Y / X ≦ 0.07 Formula 1
4.0 ≦ Y / Z ≦ 12.0 Formula 2
0.5 ≦ W ≦ 5.0 Formula 3
In the formula, X is the amount of the isophthalic acid component having a sulfonate group in the modified polyester (number of moles), Y is the amount of lithium atom (number of moles), and Z is the amount of phosphoric acid (number of moles).
W is the amount of polyethylene glycol copolymerized on the modified polyester (wt%)

By simultaneously satisfying these formulas 1, 2, and 3 , it is possible to provide a modified polyester composition excellent in polymer color tone by controlling the rate of increase in the filtration pressure during melt spinning.

As a result of intensive studies, the inventors of the present invention have found that the mass ratio of phosphoric acid and SI component and the mass ratio of lithium atom and phosphoric acid are the filtration pressure and polymer color tone during melt spinning. The present invention has been found.

  The present invention is described in detail below. The modified polyester in the present invention is intended for a modified polyester obtained by copolymerizing polyethylene glycol and SI using a direct heavy oligomer having terephthalic acid as a main acid component and ethylene glycol as a main glycol component. One of the characteristics of the present invention is that the ratio of the amount of lithium atoms to the SI component is defined within the range of the formula 1.

0.01 ≦ Y / X ≦ 0.07 Formula 1
In the formula, X is the amount of the isophthalic acid component having a sulfonate group in the modified polyester (number of moles), Y is the amount of lithium atom (number of moles), and Z is the amount of phosphoric acid (number of moles).
More preferably, 0.04 ≦ Y / X ≦ 0.07.

  If it is less than 0.010, it is satisfactory in terms of suppressing the increase in filtration pressure, but diethylene glycol as a by-product tends to increase, the amount of diethylene glycol produced is difficult to control, and a dyeing difference is likely to occur when dyeing. On the other hand, if it exceeds 0.07, the increase in filtration pressure tends to increase rapidly with the addition amount as the inflection point, and the polymer color tends to become yellowish.

Another feature of the present invention resides in defining the amount ratio of lithium atoms and phosphoric acid within the range of Formula 2.

4.0 ≦ Y / Z ≦ 12.0 Formula 2
More preferably, 7.0 ≦ Y / Z ≦ 12.0.

  If it is less than 4.0, it is satisfactory in terms of suppression of increase in filtration pressure and bluish polymer color, but diethylene glycol as a by-product is likely to increase, and the amount of diethylene glycol produced is difficult to control and dyes as fibers. It becomes easy to make a dyeing difference. If it exceeds 12.0, the amount of diethylene glycol produced decreases, but the increase in filtration pressure tends to increase.

  Such modified polyesters are used, for example, for aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid and diphenyldicarboxylic acid, and aliphatic dicarboxylic acids such as sebacic acid, adipic acid and 1,4-cyclohexanedicarboxylic acid. It may be contained to the extent that it is not impaired. Further, aliphatic diol compounds such as trimethylene glycol, tetramethylene glycol, cyclohexane-1,4-dimethanol, and neopentyl glycol, and aromatic diol compounds such as bisphenol A and bisphenol S may be contained to such an extent that the purpose is not impaired. good.

  Specific examples of the SI component in the present invention include 5-sodium sulfoisophthalic acid, 5-sodium sulfoisophthalic acid dimethyl ester, 5-sodium sulfoisophthalic acid diethyl ester, 5-sodium sulfoisophthalic acid glycol ester, and 5-lithium. Examples include sulfoisophthalic acid, 5-lithium sulfoisophthalic acid dimethyl ester, 5-lithium sulfoisophthalic acid diethyl ester, 5-lithium sulfoisophthalic acid diglycol ester, and the like. Sodium sulfoisophthalic acid glycol ester is preferred.

  The copolymerization amount of these SI components is preferably 0.5 to 5.5 mol% with respect to the produced polyester. When the content is 0.5 mol% to 5.5 mol%, sufficient dyeability can be obtained and the degree of color developability is also good. It is preferable because the spinning property is not improved, the S component is not thickened, the SI component content does not vary, and the yarn can be produced under stable conditions. In order to obtain better spinnability and dyeability, the amount is more preferably 1.5 to 4.5 mol%.

  In the present invention, the lithium atom content needs to satisfy the range of Formula 1. Examples of the lithium atom include acetates, hydroxides, formates and the like, and acetates are particularly preferable. When other alkali metal compounds are used in combination, the production of diethylene glycol as a by-product can be suppressed, and a higher quality polyester can be obtained. Specific examples of the alkali metal compound that can be used include sodium, potassium and lithium hydroxides, acetates and formates. In particular, lithium compounds are preferably used.

The phosphoric acid content needs to satisfy Formula 2.

  The molecular weight of polyethylene glycol to be copolymerized is preferably 600 to 4000. When the molecular weight is 600 to 4000, the effect of improving dyeability per unit weight is sufficiently obtained, and the oxidative degradation resistance is also satisfactory.

The amount of polyethylene glycol added is required to be 0.5 to 5.0% by weight with respect to the resulting modified polyester. When the content is 0.5 to 5.0% by weight, the effect of improving dyeability per unit weight can be sufficiently obtained, and the resistance to oxidative degradation is also satisfactory.

  As the antioxidant, a known hindered phenol-based antioxidant can be used. In particular, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (for example, IR1010 manufactured by Ciba Specialty Chemicals) is preferable. The addition amount is preferably 0.025 to 0.15% by weight based on the resulting modified polyester.

  As the polycondensation catalyst in the present invention, metal compounds such as antimony, germanium, and titanium generally used in the production of polyester can be used.

  Further, in the present invention, a light resistance imparting agent such as a manganese compound, a known additive such as a defoaming material such as a silicon compound, a matting agent such as titanium oxide, etc. You may use for.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Each characteristic described in the present invention was measured by the following method.
(1) Polymer color tone The color tone of the polyester molded product was measured with a color computer manufactured by Suga Test Instruments Co., Ltd. and indicated by b value. ◎: 10 or less, ○: more than 10 or less, 14: x 14 or more (2) Increase in filtration pressure 4 kg of polymer melted at 290 ° C. is passed through a pack provided with a 5 μm non-woven filter having an inner diameter of 25 mm, and at the start of passage and passage The pressure difference applied to the inside of the pack at the end was determined and judged in the following three stages. If it is 3.5 MPa or less, there is no practical problem, and 1.2 MPa or less is more preferable.

A: 1.2 MPa or less, O: 1.2 MPa to 3.5 MPa or less, X: 3.5 MPa or more Example 1
A slurry of terephthalic acid and ethylene glycol (the molar ratio of ethylene glycol / terephthalic acid is 1.2) was continuously fed for 3 hours to the esterification reactor in which bis (2-hydroxyethyl) terephthalate and its oligomer were present. During the supply of the slurry, a pressure of 0.2 MPa was applied to the esterification reaction apparatus, and an esterification reaction was performed at 250 ° C. to obtain a direct heavy oligomer having an esterification reaction rate of 97.5% in a reaction time of 4 hours. The charged esterification reaction product was transferred to a polycondensation reaction can. To the straight oligomer, 0.01 mol% of phosphoric acid is added to the resulting modified polyester. After 7 minutes, 0.04 wt% of antimony trioxide, 0.08 wt% of IR1010, and manganese acetate are added. 0.01 wt% and 0.11 mol% lithium acetate were added. Thereafter, 4.0% by weight of polyethylene glycol having a molecular weight of 1000 was added, and SI component was added so as to be 2.4 mol% (0.4% as S content). Thereafter, 0.1% by weight of titanium dioxide was added, the pressure was gradually reduced from normal pressure, the temperature was gradually raised from 230 ° C. to 290 ° C., and a high vacuum of 0.1 kPa or less was maintained for 3 hours. The polycondensation reaction was carried out until it reached 0.70. The properties of the resulting modified polyester are shown in Table 1.

Examples 2-7, Comparative Examples 1, 2, 4, 5
A modified polyester was produced in the same manner as in Example 1 except that the SI component, lithium atom, and phosphoric acid contents were the values shown in Table 1. The properties of the resulting modified polyester are shown in Table 1.

  As is apparent from Table 1, it can be seen that all of the examples according to the present invention have low filtration pressure and excellent polymer color tone, whereas the comparative examples have high filtration pressure or poor polymer color tone.

Claims (1)

A modified polyester obtained by copolymerizing an isophthalic acid component having a polyethylene glycol and a sulfonate group using a direct heavy oligomer mainly composed of terephthalic acid and ethylene glycol satisfies the following formulas 1, 2, and 3 simultaneously. A modified polyester characterized by that.
0.01 ≦ Y / X ≦ 0.07 Formula 1
4.0 ≦ Y / Z ≦ 12.0 Formula 2
0.5 ≦ W ≦ 5.0 Formula 3
In the formula, X is the amount of the isophthalic acid component having a sulfonate group in the modified polyester (number of moles), Y is the amount of lithium atom (number of moles), and Z is the amount of phosphoric acid (number of moles).
W is the amount of polyethylene glycol copolymerized on the modified polyester (wt%)