JPH0745567B2 - Method for producing polyester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing polyester.
More specifically, it relates to a method for producing a polyester by adding a specific amount ratio of calcium carbonate and a phosphorus compound, and more specifically, a polyester suitable for a white polyester film used as a substrate for cards, labels, display plates, white plates, etc. The present invention relates to a manufacturing method of.

[Prior Art] Polyester typified by polyethylene terephthalate has excellent physical and chemical properties and is widely used as fibers, films, and other molded articles. Among these applications, white films are used as substrates for cards, labels, display boards, white boards and the like.

Conventionally, it is well known to add a large amount of white inorganic particles to polyethylene terephthalate in order to obtain a white film. For example, there are an example in which a large amount of titanium oxide and barium sulfate are added (Japanese Patent Publication No. 56-4901) and an example in which a large amount of barium sulfate is added (Japanese Patent Publication No. 60-30930).

Further, Japanese Patent Publication No. 43-12013 discloses that a large amount of calcium carbonate is added.

However, in the above-mentioned conventional technology, it is difficult to disperse particles with barium sulfate added, and since titanium oxide absorbs visible light of 380 nm or less, it is sufficient when a film is formed using the obtained polyester. A film having whiteness and hiding power cannot be obtained.

Further, for example, when a large amount of calcium carbonate as exemplified in Japanese Patent Publication No. 43-12013 is simply added to the polyester reaction system, agglomeration of particles occurs and a yellowish polymer is obtained, which is preferable. Absent.

On the other hand, when a large amount of calcium carbonate is dry-blended with polyester during melt molding, bubbles are generated during melt extrusion, and a uniform film cannot be obtained.

[Problems to be Solved by the Invention] An object of the present invention is to add a specific amount of carbonic acid in order to improve the aggregation of particles and deterioration of polymer color tone which occur when a large amount of calcium carbonate is added to a polyester reaction system. By adopting a method for producing a polyester in which a phosphorus compound having a specific quantitative ratio to calcium is added to calcium carbonate in combination, the conventional drawbacks described above are solved.

[Means for Solving Problems] The above-mentioned object of the present invention is to produce a polyester by reacting a dicarboxylic acid or an ester-forming derivative thereof with ethylene glycol, and at any stage of the polyester production process (A ) More than 5% by weight and not more than 50% by weight based on the polyester capable of obtaining calcium carbonate having an average particle size of 0.05 to 5 μm, and (B) a phosphorus compound in a molar ratio of 0.0005 to 0.1 with respect to calcium carbonate. It can be achieved by a method for producing a polyester, which is characterized by adding 0.01 to 2% by weight.

The polyester of the present invention is produced by transesterification or esterification reaction of dicarboxylic acid or its ester-forming derivative with ethylene glycol, and polycondensation reaction. Fiber for the type of polyester,
There is no particular limitation as long as it can be formed into a film or other molded product. 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, with polyethylene terephthalate being preferred. Of course, these polyesters may be homopolyesters or copolyesters, and examples of components to be copolymerized include diethylene glycol, neopentyl glycol, polyalkylene glycol having an average molecular weight of 150 to 20000, p-xylene glycol, 1 , 4-cyclohexanedimethanol,
5-Sodium sulforesorcin and other diol components, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6
Examples include dicarboxylic acid components such as naphthalene dicarboxylic acid and 5-sodium sulfoisophthalic acid, polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid.

The calcium carbonate referred to in the present invention may be either a natural product or a synthetic product, and its crystal form includes, but is not limited to, calcite, aragonite, vaterite and the like.

The calcium carbonate may be surface-treated with stearic acid, polyacrylic acid, a silane coupling agent, a titanium coupling agent, or the like, and a surfactant such as sodium dodecylbenzenesulfonate may be used in combination.
Further, a metal oxide such as magnesium oxide, aluminum oxide, or silicon dioxide may be contained.

The average particle size of calcium carbonate must be 0.05 to 5μ, preferably 0.1 to 3μ, and more preferably 0.2 to
2μ. If the average particle size is less than 0.05 μ, the particle dispersibility in polyester is poor, and if the average particle size exceeds 5 μ, when a film is formed, the hiding power is inferior and the target film of the present invention cannot be obtained.

Further, the addition amount of calcium carbonate in the present invention must be more than 5% by weight and 50% by weight or less, preferably 7% by weight.
-40% by weight, more preferably 10-30% by weight.

When the added amount is 5% by weight or less, when the obtained polyester is film-formed, the whiteness and the hiding power of the target film are insufficient. If the amount added exceeds 50% by weight, the dispersibility of particles in the polyester may be poor, or the film strength may be insufficient.

The phosphorus compound as used in the present invention means a compound which contains a phosphorus atom and is soluble in glycol.

Examples thereof include phosphoric acid, phosphorous acid, phosphonic acid and derivatives thereof, and specifically, phosphoric acid, phosphorous acid,
Phosphoric acid trimethyl ester, phosphoric acid tributyl ester, phosphoric acid triphenyl ester, phosphoric acid mono or dimethyl ester, phosphorous acid trimethyl ester, methylphosphonic acid, methylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, etc. I can give you. Of these, the use of phosphoric acid, phosphorous acid and their ester-forming derivatives is particularly preferred.

Furthermore, these phosphorus compounds may be used alone or in combination of two or more kinds.

The addition amount of the phosphorus compound in the present invention is 0.01 to 2% by weight based on the obtained polyester, and the molar ratio of the phosphorus compound to calcium carbonate is in the range of 0.0005 to 0.1.

Further, the preferable addition amount of the phosphorus compound is 0.07 to 1.5% by weight based on the obtained polyester, and the molar ratio of the phosphorus compound to calcium carbonate is 0.0015 to 0.07, and the more preferable addition amount of the phosphorus compound is 0.1 to 1% by weight. And the molar ratio of phosphorus compound to calcium carbonate is 0.003
~ 0.05. When the molar ratio of the phosphorus compound to calcium carbonate is less than 0.0005 or the addition amount is less than 0.01% by weight with respect to the obtained polyester, the dispersibility of calcium carbonate in the polyester becomes poor, or the obtained polyester has Color tone deteriorates and sufficient whiteness and hiding power cannot be obtained when formed into a film.

On the other hand, the molar ratio of phosphorus compound to calcium carbonate is 0.
2 for polyester that exceeds 1 or can be added
If it exceeds 5% by weight, the polymerization reactivity during the production of polyester is lowered, or the by-product diethylene glycol is increased.

As described above, the present invention aims to improve the dispersibility and color tone of calcium carbonate particles in the obtained polyester by adding a phosphorus compound to the polyester reaction system within a specific amount ratio range relative to calcium carbonate,
When the obtained polyester is formed into a film, a white film excellent in whiteness and hiding power can be obtained.

The calcium carbonate and phosphorus compounds of the present invention may be added to the polyester reaction system at any time, preferably before the esterification or transesterification reaction during polyester production and during the initial polycondensation, and more preferably the ester. It is between the end of the polymerization or transesterification reaction and the beginning of the polycondensation reaction.

Further, the method of adding the calcium carbonate and the phosphorus compound to the polyester reaction system is not particularly limited, and the calcium carbonate and the phosphorus compound may be added simultaneously or as a mixture. As a preferable addition method for obtaining particularly good dispersibility of calcium carbonate, a phosphorus compound is added and then calcium carbonate is added, and the addition interval is within 1 hour, more preferably within 30 minutes.

The calcium carbonate and phosphorus compound added to the polyester reaction system may be added in the form of powder or liquid, or may be added in the form as it is, but from the viewpoint of dispersibility of calcium carbonate in polyester, an organic solvent such as glycol is appropriately used. The method of adding in a mixed slurry or liquid state is preferable. Further, these slurries and liquids may be added after heat treatment.

The polyester of the present invention is a metal compound catalyst such as lithium, sodium, calcium, magnesium, manganese, zinc, cobalt, antimony, germanium, and titanium, which is usually used during production, an antioxidant, a pigment, a fluorescent whitening agent, and a surface active agent. Agents, antistatic agents, and inorganic particles other than calcium carbonate can be appropriately added as necessary.

When a film is produced from the polyester to which the calcium carbonate and the phosphorus compound of the present invention are added, the polyester is molded into a sheet by a usual method and stretched 2.5 to 4.0 times in the biaxial direction by a conventional method. It is then manufactured by heat setting at a temperature of 150 ° C or higher.

The preferred density of the biaxially stretched film using the polyester obtained by the production method of the present invention is 1.10 to 1.38 g / c
m ³ , more preferably 1.15 to 1.35 g / cm ³ . Density is 1.1
When it is less than 0, the productivity and mechanical properties of the film are inferior, and when the density exceeds 1.38, preferable whiteness of the film cannot be obtained.

The polyester obtained by the method of the present invention can be preferably used in the field of molded articles other than films, such as fibers.

[Examples] The present invention will be described in more detail with reference to Examples.

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 Polymer chips were placed in a heating bath and heated at 6 ° C. for 5 minutes, and the temperature at which the tip of the load penetrated into the chips by 5 mm or more was measured.

C. Particle Dispersibility in Polymer 20 mg of the polymer was sandwiched between two cover glasses, cooled by melt press at 280 ° C., and then judged by microscopic observation.

The criteria for judgment are as follows.

◯: Aggregated particles are hardly observed. (It is within the target range of the present invention.) Δ: A few aggregated particles are observed. (It does not reach the object of the present invention.) X: Many aggregated particles are observed. (It does not reach the object of the present invention.) D. Polymer color tone It is calculated from Hunter values (L, a, b) of a polymer chip color machine (manufactured by Toyo Rika) based on the method of JIS L1073.

⊚: Whiteness 70 or more (particularly preferred within the scope of the present invention) ◯: Whiteness 55 or more and less than 70 (within scope of the present invention) Δ: Whiteness 53 or more, less than 55 (present invention The whiteness is less than 53 (the object of the present invention is not achieved.) E. Film concealment power The visible light transmission density of a film having a thickness of 150 μ was measured by a transmission density meter TD-504 manufactured by Macbeth. It was measured and the hiding power was judged.

Transmission density [−] ×; less than 0.4 (poor hiding power) △; 0.4 to less than 0.7 (slightly hiding power) ○; 0.7 to less than 1.0 (good hiding power) ◎; 1.0 or more (very good hiding power) where The so-called transmission density is calculated by the following equation.

D = -log (T / 100) Example 1 85 parts by weight of dimethyl terephthalate, ethylene glycol
After transesterifying 60 parts by weight with 0.09 parts by weight of calcium acetate as a catalyst according to a conventional method, 10% by weight of trimethyl phosphate was used as a phosphorus compound so that the amount was 0.273% by weight with respect to the polymer (molar ratio to calcium carbonate 0.0130). Add the containing ethylene glycol solution,
After 10 minutes, 37.5 parts by weight of an ethylene glycol slurry containing 40% by weight of calcium carbonate having an average particle diameter of 0.9μ was added, and then 0.03 parts by weight of antimony trioxide was added as a polymerization catalyst.

Then, polycondensation reaction was performed according to a conventional method under reduced pressure at high temperature to obtain polyethylene terephthalate having an intrinsic viscosity of 0.643 and a softening point of 259.7 ° C. As a result of observing the dispersed state of polymer calcium carbonate particles, no aggregated particles were observed. The color tone of the obtained polymer was very high with a whiteness of 71.1.

Fluorescent brightener "O" based on 100 parts by weight of the obtained polyester
B-1 "(manufactured by Eastman Co.) was blended in an amount of 0.03 parts by weight and biaxially stretched 3.2 times in the length direction and 3.2 times in the width direction to obtain a film having a thickness of 150 µ. The density of the obtained film was 1.30 and bubbles such as bubbles were formed. There were no defects, and the whiteness and hiding power were excellent.

Example 2 Polyethylene terephthalate was obtained in the same manner as in Example 1 except that calcium carbonate having an average particle diameter of 0.4 μm and a phosphorus compound were mixed in advance and then added to the polyester reaction system. The dispersibility of particles in the polymer and the color tone were excellent.

A film was produced in the same manner as in Example 1, but the film was excellent in whiteness and hiding power without defects such as bubbles.

Comparative Example 1 Polyethylene terephthalate was obtained in the same manner as in Example 1 except that calcium carbonate having an average particle diameter of 0.04 μ was used. As a result of observing the particle dispersion state of calcium carbonate in the polymer, many agglomerated particles were observed in the polymer. Further, a film was produced from the polyester in the same manner as in Example 1. Coarse projections appeared on the surface of the film due to agglomerated particles, and the hiding power of the film was somewhat poor.

Examples 3 to 9 and Comparative Examples 2 to 8 Polyesters and films were produced in the same manner as in Example 1 except that the calcium carbonate and phosphorus compounds added as described in Table 1 were changed. The results are shown in Table 1.

Examples 3 to 9 were within the scope of the present invention, and were excellent in particle dispersibility and color tone, and the films obtained from the polyester had good whiteness and hiding power without any bubble defects.

On the other hand, in Comparative Example 2, the average particle diameter of calcium carbonate is outside the range of the present invention, the film produced from the obtained polyester has a poor hiding power, and the film surface protrusion is large.

In Comparative Examples 3, 4, 5, and 6, the molar ratio of the phosphorus compound to calcium carbonate and the amount added were outside the scope of the present invention, and many agglomerated particles were observed in the obtained polyester, and the whiteness was low. However, there are drawbacks such as a polymer having a strong yellowish color, a decrease in polycondensation reactivity, and a decrease in softening point. In Comparative Examples 7 and 8, the amount of calcium carbonate added was outside the range of the present invention and the film hiding power was poor,
There were drawbacks such as poor particle dispersibility.

Example 10 85 parts by weight of dimethyl terephthalate, ethylene glycol
60 parts by weight and 0.09 parts by weight of calcium acetate as a catalyst were subjected to a transesterification reaction according to a conventional method, and then the average particle size was measured.
37.5 parts by weight of an ethylene glycol slurry containing 40% by weight of 0.9μ calcium carbonate was added. After 15 minutes, an ethylene glycol solution containing 10% by weight of trimethyl phosphate was added as a phosphorus compound in an amount of 0.273% by weight to the polymer (molar ratio to calcium carbonate 0.0130), and then 0.03 parts by weight of antimony trioxide was added as a polymerization catalyst. did.

After that, polycondensation reaction was carried out according to a conventional method under reduced pressure at high temperature to obtain polyethylene terephthalate having an intrinsic viscosity of 0.638 and a softening point of 259.6 ° C. As a result of observing the particle dispersion state of calcium carbonate of the polymer, almost no aggregated particles were observed.
Further, the color tone of the obtained polymer was 61.0, and it was preferable that the polymer also had little yellowness. Fluorescent whitening agent "OB-1" (Eastman) to 100 parts by weight of the obtained polyester
0.03 parts by weight were blended and biaxially stretched 3.2 times in the length direction and 3.2 times in the width direction according to a conventional method to obtain a film having a thickness of 150 μ. The obtained film had a density of 1.31 and had no defects such as bubbles, and was excellent in whiteness and hiding power.

[Effects of the Invention] The present invention, as described above, by adding calcium carbonate and phosphorus compounds having a specific amount and a specific amount ratio of average particle diameter of 0.05 to 5μ into the polyester reaction system, aggregation which has hitherto not been obtained. It does not contain particles and has high whiteness,
A polyester with less yellowness can be obtained.

When the polyester obtained by the production method of the present invention is molded into a film, clogging in the melt film-forming step is reduced, air bubbles are prevented from being generated during melt extrusion, and film breakage is eliminated, whiteness and hiding power are excellent. White film can be produced, printing paper, X-ray intensifying screen, card,
It is preferably used as a base material for labels, display boards, white boards, and decorative purposes.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 61-28522 (JP, A) JP-A 59-197424 (JP, A) JP-A 59-145214 (JP, A) JP-B 53- 21712 (JP, B2)

Claims (1)

[Claims] 1. When a polyester is produced by reacting a dicarboxylic acid or its ester-forming derivative with ethylene glycol, (A) calcium carbonate having an average particle diameter of 0.05 to 5 μm is obtained at any stage of the polyester production process. More than 5% by weight to polyester and 50% by weight
A method for producing a polyester comprising the following and (B) a phosphorus compound in a molar ratio to calcium carbonate in the range of 0.0005 to 0.1 and 0.01 to 2% by weight based on the obtained polyester.