JP2560685B2 - Method for producing polyester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polyester. More specifically, it relates to a method for producing a polyester by adding an organosol in which fine particles of silicon dioxide are present in a glycol-based dispersion medium.

[Prior art and its problems]

Polyester, represented by polyethylene terephthalate, has excellent physical and chemical properties,
Widely used as film and other molded products.
However, slippage is poor in terms of process passability in the molding process for obtaining these molded products, post-processing processes such as surface treatment or the handleability of the product itself, which deteriorates workability and reduces product value. There is no property. For this reason, it is usually practiced to incorporate fine particles into polyester to improve the surface smoothness of the molded product by giving appropriate irregularities to the surface of the molded product.

As such fine particles, inorganic compound particles insoluble in polyester such as talc, silica, kaolin, aluminum oxide, titanium dioxide and carbon are used. Among them, silica particles are various products having different average particle diameters. Is often used because it is commercially available.

As a method of adding silica particles to polyester, powdery silica is physically mixed in a dispersion medium such as water, methanol or glycol, or is further dispersed by using a surfactant and a dispersant in combination to produce a polyester in a slurry form. As disclosed in JP-A-59-108028, JP-A-56-47429, etc., glycol is added little by little to aqueous colloidal silica to remove water by distillation. A method of adding to the polyester reaction system, or a method of adding 1.0 mol% or less of alkali to the reaction system in terms of M ₂ O (M represents an alkali metal atom) with respect to glycol dispersion medium system colodal silica and silica. It has been known.

Such a method described above, compared with the method of adding powdery silica in a slurry form to the polyester reaction system, the silica particles in the dispersion medium before addition and the dispersion state of the silica particles in the obtained polyester are slightly good. Become.

However, in any of the methods, particles having relatively high surface activity such as silica particles, which tend to form secondary particles due to aggregation, are completely dissolved in the dispersion medium before being added to the polyester reaction system. It is difficult to disperse the particles into the polyester, and when added to the polyester manufacturing process, the particles aggregate.

When coarse secondary agglomerated particles are present in polyester,
In the fiber forming process, it may cause yarn breakage during high-speed spinning, and when formed into a film, the surface irregularities become uneven, reducing the value of film products, and reducing the magnetic properties of vapor-deposited tape, metal tape, etc. When applied to a tape support, it is not preferable because it causes a reduction in output and dropout.

[Object of the Invention]

The object of the present invention is to produce a polyester in which silica particles having an average particle diameter of 5 to 500 mμ are highly finely dispersed, and when a silica particle-containing polyester obtained by a conventional method is used, a molding process for fibers, films, etc. Another object is to improve the above-mentioned drawbacks found in molded articles.

[Structure of Invention]

The object of the present invention is to produce a polyester by reacting a dicarboxylic acid or its ester-forming derivative with ethylene glycol.
The water of the silicon dioxide water-dispersed sol having μ is replaced with ethylene glycol, and the replacement step or after replacement is 150 ° C. or higher 2
Heat treatment at a temperature below 00 ° C to increase the moisture content to silicon dioxide
Silicon dioxide organosol with 7.0 wt% or less,
This is accomplished by a method for producing a polyester, which comprises adding an alkali metal compound (2) and a phosphorus compound (3) so as to satisfy the following formula to a reaction system at any stage of the polyester production process.

0.005 ≤ M ₂ O / P ≤ 20 0.005 ≤ P ≤ 0.2 (where M ₂ O is mol% of the polyester when the alkali metal compound in the produced polyester is converted to an alkali metal oxide, P is a phosphorus compound relative to the produced polyester The polyester of the present invention is produced by transesterification or esterification reaction of dicarboxylic acid or ester derivative with ethylene glycol and polycondensation reaction. For the types of polyester, fibers, films,
There is no particular limitation as long as it can be molded into other molded products. Suitable polyesters that can be molded into fibers, films and other molded articles are those that use aromatic dicarboxylic acids as dicarboxylic acid components, 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'-dicarboxylate, polyethylene-2,6-naphthalene dicarboxylate Examples thereof include polyethylene terephthalate. Of course, these polyesters may be either homopolyesters or copolyesters, and as the components to be copolymerized, diethylene glycol, neopentyl glycol, average molecular weight 150 to 20000
Polyalkylene glycol, p-xylylene glycol, 1,4-cyclohexanedimethanol, diol components such as 5-sodium sulforesorcin, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 5 -Dicarboxylic acid components such as sodium sulfoisophthalic acid, polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid.

The average particle size of silicon dioxide in the silicon dioxide organosol is 5 to 500 mμ, and particularly preferably 10 to 250 mμ.
If the average particle size exceeds 500 mμ, in magnetic tape applications, defects such as output reduction and dropout due to the coarsening of the film surface protrusions occur. On the other hand, when the average particle size is less than 5 mμ, the viscosity increase of the molten polymer is large and the operability during the polymerization reaction and molding process is deteriorated, and the surface projections are insufficient in the film properties, and effective lubricity cannot be obtained.

The heat treatment in the present invention is to replace the water of the silicon dioxide aqueous dispersion sol with ethylene glycol under normal pressure or reduced pressure, and then heat at 150 ° C. or higher and 200 ° C. or lower.
Further, it is preferable to perform the heat treatment for at least 5 minutes before the end of the heat treatment without substantially removing water. If the heat treatment is less than 150 ° C., the particles added to the polyester reaction system undergo secondary agglomeration, resulting in clogging of the filter during film forming, film tearing, coarse projections, etc., and the object of the present invention cannot be achieved. Further, when the silicon dioxide organosol is subjected to a heat treatment in a pressurized state at a temperature exceeding 200 ° C., a diethylene glycol component or the like is produced in the organosol, which is not preferable in terms of the mechanical properties of the film. The heat treatment time for obtaining good dispersibility of particles is 5
Minutes or more is preferable.

Further, the water content of the silicon dioxide after the heat treatment in the present invention needs to be 7.0% by weight or less, preferably 6.0% by weight or less, and more preferably 5.0% by weight or less. If the water content with respect to silicon dioxide exceeds 7.0% by weight, secondary aggregation of silicon dioxide will occur when the organosol is added to the polyester reaction system even if the heat treatment of the present invention is performed, which is not preferable.

Further, the heat-treated silicon dioxide organosol of the present invention may be added to the polyester reaction system at any time, and preferably before transesterification or esterification reaction during polyester production and during the initial stage of polycondensation reaction.

The reason why the dispersibility of the particles in the produced polyester is particularly improved by heat-treating the silicon dioxide organosol is probably that silicon dioxide and ethylene glycol react at high temperature to modify the particle surface, which is inert to aggregation. It is thought that it was because it was done.

The alkali metal compound of the present invention is used for the purpose of preventing agglomeration of silicon dioxide in polyester, and the addition method thereof is to add it to the organosol before or after the heat treatment of the silicon dioxide organosol, and then carry out the polyester reaction. Examples thereof include a method of adding to the system or a method of adding to the polyester reaction system separately from the organosol. Further, it may be added to the polyester reaction system at any time, and preferably from before the transesterification or esterification reaction at the time of polyester production to the early stage of the polycondensation reaction.

Examples of the type of alkali metal include Li, Na, K and the like, and the type of compound is not particularly limited, but lithium acetate, sodium acetate, Glycol-soluble compounds such as potassium acetate are preferred. Further, the alkali metal compound contained in the production of the silicon dioxide aqueous dispersion sol can also be used as a part of the alkali metal compound added in the present invention.

The amount of the alkali metal compound added is M ₂ O (in terms of mol% relative to the polyester when the alkali metal compound in the produced polyester is converted to an alkali metal oxide,
M represents an alkali metal atom. ) Is preferably 0.2 mol% or less from the viewpoint of preventing secondary aggregation of silicon dioxide or formation of coarse particles due to an alkali metal compound.

The addition amount of the phosphorus compound in the present invention is required to be added to the reaction system in the polyester manufacturing process so as to satisfy the following formula, and 0.005 ≦ M ₂ O / P ≦ 20 0.005 ≦ P ≦ 0.2 preferably 0.01 ≦ M ₂ O / P ≦ 10 0.01 ≦ P ≦ 0.1.

(However, P represents the mol% of the phosphorus compound with respect to the produced polyester.) When M ₂ O / P exceeds 20 or P is less than 0.005, when the organosol is added to the polyester, secondary aggregation of silicon dioxide or Coarse particles are generated due to the alkali metal compound. Further, when M ₂ O / P is less than 0.005 or P exceeds 0.2, a large amount of phosphorus compound is added, so that silicon dioxide forms secondary aggregation in the polyester due to the phosphorus compound, Coarse particles are generated by the phosphorus compound, and the polymerization reactivity decreases.

Examples of the phosphorus compound in the present invention include compounds such as phosphoric acid, phosphorous acid, mono-, di- or triesters of phosphoric acid, phosphonic acid and phosphonate.

The addition method of the phosphorus compound of the present invention is preferably a method of adding to the polyester reaction system after being added to the organosol before or after the heat treatment of the silicon dioxide organosol, or a method of adding to the polyester reaction system separately from the organosol. . When the phosphorus compound is added separately from the organosol, the phosphorus compound may be added to the polyester reaction system at any time, preferably from before the transesterification or esterification reaction during the production of the polyester to the initial stage of the polycondensation reaction.

The amount of silicon dioxide added to the polyester in the present invention is not particularly limited, but from the viewpoint of increasing the viscosity of the molten polymer and dispersibility of the added particles, it is 10% by weight or less, especially 5% by weight.
Weight% or less is suitable.

In addition, metal compounds such as lithium, sodium, calcium, magnesium, manganese, zinc, antimony, germanium, and titanium, which are usually used in the production of polyester, catalysts, pigments, surfactants, and inorganic particles other than silicon dioxide are also used as necessary. Can be added.

〔The invention's effect〕

In the present invention, as described above, silicon dioxide having an average particle diameter of 5 to 500 mμ is present in an ethylene glycol dispersion medium,
And by adding an organosol and a specific amount of an alkali metal compound and a phosphorus compound which have been heat-treated into the polyester reaction system, secondary agglomerated particles and coarse particles that have not been obtained conventionally are not included, and uniform fine particles. A polyester containing a large number of is obtained.

The polyester obtained by the production method of the present invention can reduce clogging, yarn breakage, and film tear elimination in the production process of a molded article, and of course, can obtain a molded article having surface irregularities that are highly uniformly refined. Therefore, it can be preferably used in the field of fibers, films and other molded articles, particularly in the field of films where slipperiness and fineness of surface irregularities are strongly required.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The characteristics in the examples were measured as follows.

1) Intrinsic viscosity of polymer Measured at 25 ° C. using 0-chlorophenol as a solvent.

2) Softening point of polymer A polymer chip was placed in a heating bath and heated at a temperature rising rate of 6 ° C / 5 minutes, and the temperature at which the tip of the load penetrated into the chip by 5 mm or more was measured.

3) State of particle field in polymer A. Observation of particle dispersion state The polymer was cut into an ultrathin film of approximately 1000 Å using an ultrathin film preparation device, and then the state of particle dispersion in the polymer was observed by a transmission electron microscope. The judgment was made as follows.

◯: No secondary aggregated particles are observed.

Δ: The secondary agglomerated particles are slightly present and the purpose is not achieved.

×: Most of the particles are secondary aggregated particles.

B. Observation of Coarse Particles 1 mg of polymer was sandwiched between two cover glasses, melted at 290 ° C. to form a thin film, then rapidly cooled, and observed with a microscope.

 The judgment was made as follows.

◯: Coarse particles are not observed.

Δ: There are slightly coarse particles and the purpose is not achieved.

X: Many coarse particles are present.

4) Moisture content with respect to silicon dioxide in organosol About 50 mg of silicon dioxide organosol was sampled and measured with a digital trace moisture analyzer manufactured by Mitsubishi Kasei Co., Ltd. to calculate the water content with respect to silicon dioxide.

Example 1 Ethylene glycol was added to an aqueous sol of 40% by weight of silicon dioxide containing an average particle size of 30 mμ and 0.80% by weight of Na (relative to solid content), and ethylene glycol was added at 85 ° C. under reduced pressure to finally obtain 10
The substitution was completed at 0 ° C., and an organosol containing 20% by weight of silicon dioxide and containing 10% by weight of water relative to silicon dioxide was obtained. Next, the organosol was diluted with ethylene glycol so as to contain 5% by weight of silicon dioxide, transferred to a heating container equipped with a rectification column, gradually heated under stirring, and heated at normal temperature boiling point for 30 minutes. Then, the rectification column was switched to total reflux and heat treatment was carried out for 1 hour. The water content of the organosol after the heat treatment was 3.0% by weight based on silicon dioxide.
Next, 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol and 0.003 parts by weight of lithium acetate, 0.05 parts by weight of magnesium acetate as a catalyst according to a conventional method, after transesterification, 20 parts by weight of the heat-treated organosol. 0.042 part by weight of trimethyl phosphate was added, and then 0.02 part 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 0.618 and a softening point of 260,5 ° C.

Na in the obtained polymer, Li, respectively atomic absorption method quantification of P, Na ₂ O and Li ₂ O where was the line summer colorimetrically 0.03
At 3 mol% and 0.0028 mol%, P was 0.052 mol% and M ₂ O / P was 0.688. As a result of observing particles in the polymer, as shown in Table 1, neither secondary aggregated particles nor coarse particles were observed.

Blend the obtained polyester with polyethylene terephthalate that does not substantially contain particles,
A biaxially stretched film having a particle size of 12 μm and a particle content of 0.05% by weight was obtained. When the surface of the film was observed, no coarse protrusion was observed.

Comparative Example 1 In the same manner as in Example 1, the heat-treated organosol and 0.001 part by weight of trimethyl phosphate were added.

Na ₂ O and Li ₂ O in the obtained polymer were 0.033, respectively.
Mol%, 0.0028 mol%, P is 0.001 mol%, M ₂ O / P
Was 35.8.

As a result of observing the particles in the obtained polymer, slightly secondary agglomerated particles were present and a large number of coarse particles were observed. Coarse protrusions appeared on the surface of the biaxially stretched film obtained from this polymer.

Examples 2 to 6 and Comparative Examples 2 to 4 The silicon dioxide-containing polyethylene terephthalate shown in Table 1 was obtained in the same manner as in Example 1 except that the conditions shown in Table 1 were used.

Examples 2, 3, 4, 5, and 6 were within the scope of the present invention, and as a result of observing the particles in the polymer, neither secondary aggregation particles nor coarse particles were observed in any of the polymers.

On the other hand, Comparative Example 2 has a water content relative to silicon dioxide in the organosol after the heat treatment, Comparative Example 3 has a P content in the polyester within the range of the present invention, and Comparative Example 4 does not perform the organosol heat treatment. Is something
As a result of observing particles in the obtained polymers, secondary aggregation particles or coarse particles were recognized in all the polymers.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08K 5/524 KKD C08K 5/524 KKD C08L 67/02 KJS C08L 67/02 KJS // C08L 67: 02

Claims (1)

(57) [Claims] 1. When producing a polyester by reacting a dicarboxylic acid or an ester-forming derivative thereof with ethylene glycol, (1) water of a silicon dioxide aqueous dispersion sol having an average particle diameter of 5 to 500 mμ is converted into ethylene glycol. Substituting, 150 ℃ or more 200 ℃, or after the replacement step
Heat treated below to obtain a moisture content of 7.0
A silicon dioxide organosol in an amount of up to 50% by weight, (2) an alkali metal compound and (3) a phosphorus compound are added to the reaction system at any stage of the polyester production process so as to satisfy the following formula. Production method. 0.005 ≤ M ₂ O / P ≤ 20 0.005 ≤ P ≤ 0.2 (where M ₂ O is mol% of polyester when the alkali metal compound in the produced polyester is converted to alkali metal oxide, P is phosphorus compound relative to the produced polyester Mol% of.)