JP2625833B2 - Polyester production method - Google Patents

Description

The present invention relates to a method for producing a polyester. More specifically, the present invention relates to a method for producing a polyester obtained by adding a large amount of calcium carbonate. The present invention relates to a method for producing a polyester, which is suitable as the above.

[Conventional technology]

Polyesters represented by polyethylene terephthalate have excellent physical and chemical properties and are widely used as fibers, films and other molded products. In particular, among these uses, white films are used as substrates for cards, labels, display boards, white boards, and the like.

Conventionally, it is well known that a large amount of white inorganic particles is added to polyethylene terephthalate to obtain a white film. For example, there is an example in which titanium oxide and barium sulfate are added in large amounts (Japanese Patent Publication No. 56-4901) and an example in which barium sulfate is added in large amounts (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 technique, the addition of barium sulfate is inferior in the dispersibility of the particles, and a film having sufficient whiteness and hiding power cannot be obtained when a film is formed using the obtained polyester. . On the other hand, a film to which titanium oxide is added has a high hiding power due to a high refractive index of the particles, but a film having a sufficient whiteness cannot be obtained.

Further, for example, when a large amount of calcium carbonate as exemplified in Japanese Patent Publication No. 43-12013 is added to a polyester reaction system, aggregation of particles occurs, or a strong yellowish polymer is obtained, which is not preferable. It is difficult to combine sufficient whiteness and hiding power. In addition, when adding inorganic particles such as calcium carbonate to the polyester reaction system, it is common to use a slurry prepared with an organic solvent such as glycol beforehand. The addition of the particle slurry is not preferable because the particles settle and agglomerate in the reaction system. Further, there is a drawback that a decrease in the temperature of the reaction system caused during the addition of the slurry causes a decrease in productivity.

[Problems to be solved by the invention]

An object of the present invention is to improve the sedimentation, aggregation, and deterioration of the polymer color tone of the resulting particles when a large amount of calcium carbonate is added to the polyester reaction system, and to further improve the particle dispersibility in the obtained polyester, the whiteness of the film, and the hiding. In order to improve the properties, a calcium carbonate-containing ethylene glycol slurry heated at a specific temperature, and a polyester production method of adding a specific amount of a phosphorus compound to the calcium carbonate to the polyester reaction system, It is to solve the above-mentioned conventional disadvantages.

[Means for solving the problem]

An object of the present invention is to produce a polyester by reacting a dicarboxylic acid or an ester-forming derivative thereof with ethylene glycol, at any stage of the polyester production step, in the state of ethylene glycol slurry at 50 ° C to boiling point. 5 to 60% by weight with respect to the polyester from which calcium carbonate having an average particle size of 0.05 to 5 µ obtained by heating at a temperature of less than 5%,
And a phosphorus compound having a molar ratio of 0.0005 to 0.2 with respect to calcium carbonate is added to the reaction system.

The polyester of the present invention is produced by a transesterification or esterification reaction of a dicarboxylic acid or an ester-forming derivative thereof with ethylene glycol and a polycondensation reaction. The type of polyester is not particularly limited as long as it can be formed into fibers, films, and other molded products. Suitable polyesters that can be formed into fibers, films, and other molded articles include those in which the dicarboxylic acid component is an aromatic dicarboxylic acid, such as polyethylene terephthalate, polyethylene-p-oxybenzoate, and polyethylene-1,2-bis. (2-chlorophenoxy) ethane-4,4'-dicarboxylate, polyethylene-1,2-bis (phenoxy) ethane-
Examples thereof include 4,4'-dicarboxylate and polyethylene-2,6-naphthalene dicarboxylate, and among them, polyethylene terephthalate is preferable. Of course, these polyesters may be homopolyesters or copolyesters, and the copolymerizable components include, for example, diethylene glycol, neopentyl glycol,
Polyalkylene glycol having an average molecular weight of 150 to 20,000, p
Diol components such as -xylene glycol, 1,4-cyclohexanedimethanol, 5-sodium sulforesorcin, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 5-sodium sulfoisophthalic acid, etc. Examples thereof include a polycarboxylic acid component such as a dicarboxylic acid component, trimellitic acid and pyromellitic acid, and an oxycarboxylic acid component 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 crystalline form is calcite,
Examples include aragonite and vaterite, but are not particularly limited.

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

The average particle size of the calcium carbonate needs to be 0.05 to 5μ, preferably 0.1 to 3μ, more preferably 0.2 to 3μ.
２2μ. If the average particle size is less than 0.05μ, the particle dispersibility in the polyester is inferior, and if the average particle size exceeds 5μ, when a film is formed, the film which is a target of the present invention such as poor hiding power cannot be obtained. .

The calcium carbonate-containing ethylene glycol slurry in the present invention must be heated at 50 ° C. to less than the boiling point and added to the polyester reaction system, preferably at 60 to 180 ° C., more preferably at 70 to 150 ° C. If the heating temperature of the slurry is less than 50 ℃, settling in the polyester reaction system,
When the film is formed due to agglomeration, the film intended for the present invention cannot be obtained, such as poor concealing power. When the heating temperature exceeds the boiling point, agglomeration of particles occurs in the slurry,
Poor particle dispersibility in the resulting polyester.

The heating time of the calcium carbonate-containing ethylene glycol slurry is not particularly limited, but is preferably 5 minutes or more, more preferably 30 minutes or more.

Further, the addition amount of calcium carbonate in the present invention is 5 to 5.
Should be 60% by weight, preferably 7-50% by weight,
More preferably, it is 10 to 40% by weight.

When the amount of the added polyester is less than 5% by weight, and the obtained polyester is formed into a film, the whiteness of the intended film can be improved.
Inadequate hiding power. If the amount exceeds 60% by weight, the dispersibility of the particles in the polyester may be poor, or the film strength may not be sufficient.

The concentration of calcium carbonate in the calcium carbonate-containing ethylene glycol slurry of the present invention is not particularly limited, but is preferably 10 to 80% by weight, and more preferably 20 to 60% by weight. If it is too low, the by-product diethylene glycol in the polyester will increase, while if it is too high, the particle dispersibility in the polyester will tend to be poor.

The present invention is to improve the dispersibility of a large amount of calcium carbonate particles in polyester, whiteness of the film, etc.
It is necessary to add a phosphorus compound.

The phosphorus compound in the present invention refers to a compound containing a phosphorus atom in the compound and soluble in glycol.

Examples include phosphoric acid, phosphorous acid, phosphonic acid and derivatives thereof, and specifically, phosphoric acid, phosphorous acid, trimethyl phosphate, tributyl phosphate, triphenyl phosphate, monophosphate phosphate, Dimethyl ester, phosphite trimethyl ester, methylphosphonic acid, methylphosphonic acid dimethyl ester,
Examples thereof include phenylphosphonic acid dimethyl ester and phenylphosphonic acid diethyl ester. Of these, the use of phosphoric acid, phosphorous acid and their ester-forming derivatives is particularly preferred.

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

The addition amount of the phosphorus compound of the present invention must be 0.0005 to 0.2 in molar ratio to calcium carbonate, and is preferably
0.0015 to 0.1. When the molar ratio of the phosphorus compound to calcium carbonate is less than 0.0005, the dispersibility of calcium carbonate in the polyester becomes poor, or the color tone of the obtained polyester deteriorates, and when the film is formed, sufficient whiteness and opacity are obtained. I can't get the power.

On the other hand, the molar ratio of the phosphorus compound to calcium carbonate is
If it exceeds 0.2, the polymerization reactivity during the production of the polyester will decrease, or diethylene glycol as a by-product will increase.

The calcium carbonate-containing ethylene glycol slurry of the present invention and the phosphorus compound may be added to the polyester reaction system at any time, preferably during the initial period of polycondensation from before the esterification or transesterification reaction during polyester production, More preferably, it is between the end of the esterification or transesterification reaction and the beginning of the polycondensation reaction.

The method of adding the calcium carbonate-containing ethylene glycol slurry to the polyester reaction system is not particularly limited, and may be continuous or may be added in portions.

Further, the addition of the calcium carbonate-containing ethylene glycol slurry heated at 50 ° C. to less than the boiling point to the reaction system may be performed after cooling, but the heating temperature is maintained to prevent problems such as a decrease in the productivity of the polyester. The method of adding in a state in which it was added is more preferable.

As described above, the present invention improves the dispersibility of a large amount of calcium carbonate particles by adding a specific amount of a phosphorus compound to a calcium carbonate-containing ethylene glycol slurry and calcium carbonate heated at a specific temperature to a polyester reaction system. It can be measured, and when the resulting polyester is formed into a film, a white film excellent in whiteness and hiding power can be obtained.

Further, the polyester of the present invention is usually used in the production of lithium, sodium, calcium, magnesium, manganese, zinc, cobalt, antimony, germanium,
A metal compound catalyst such as titanium, an antioxidant, a pigment, a fluorescent brightener, a surfactant, an antistatic agent, and inorganic particles other than calcium carbonate can be appropriately added as necessary.

In the case of producing a film from the polyester to which the calcium carbonate of the present invention is added, the polyester is formed into a sheet by a usual method, stretched biaxially by 2.5 to 4.0 times in a usual manner, and then drawn at 150 ° C. It is manufactured by heat setting at the above temperature.

The preferred density of the biaxially stretched film using the polyester obtained by the production method of the present invention is 0.90 to 1.38 g / cm.
³ , more preferably 0.95 to 1.35 g / cm ³ . 0.90 density
When it is less than 1, the productivity and mechanical properties of the film are inferior. When the density exceeds 1.38, favorable film whiteness 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, for example, fibers.

〔Example〕

 Hereinafter, 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. Softening point of polymer Put the polymer chip in a heating bath and heat it at 6 ° C for 5 minutes.
The temperature at which the tip of the load penetrated 5 mm or more into the chip was measured.

C. Particle dispersibility in polymer 20 mg of polymer is sandwiched between two cover glasses, 280 ° C
After cooling with a melt press, it was determined by microscopic observation. The criteria are as follows.

；: Almost no aggregated particles are observed. (It is within the object of the present invention.) Δ: Slightly aggregated particles are observed. (The object of the present invention is not achieved.) ×: Many aggregated particles are observed. (The object of the present invention is not attained.) D. Polymer color tone Calculated from the hunter value (L, a, b) of a polymer chip color machine (manufactured by Toyo Rika) based on the method of JIS L1073.

A: Whiteness of 70 degrees or more (particularly preferable within the object range of the present invention) O: Whiteness of 55 or more and less than 70 (within the object range of the invention) Δ: Whiteness of 53 or more and less than 55 (book) ×: Whiteness less than 53 (does not achieve the object of the present invention) E. Film hiding power Visible light transmission density of a 150 μm thick film using a transmission density meter TD-504 manufactured by Macbeth. Was measured to determine the hiding power.

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

D = -log (T / 100) F. Film Whiteness The reflectance was determined from the reflectances R ₄₅₀ and R _{550 of a} 150 μm thick film of 450 nm and 550 nm measured with a tungsten light source using a Hitachi autograph spectrophotometer EPE-2 according to the following equation.

Whiteness (%) = 4R ₄₅₀ −3R ₅₅₀ ;; 95% or more (particularly preferable within the object of the present invention) ○: 90% or more and less than 95% (within the object of the present invention) Δ; 85% or more and less than 90% (not attain the object of the present invention) ×; less than 85% (not attain the object of the present invention) Example 1 80 parts by weight of dimethyl phthalate, ethylene glycol 60
And a transesterification reaction using 0.09 parts by weight of calcium acetate as a catalyst in accordance with a conventional method. Then, trimethyl phosphate was added as a phosphorus compound in an amount of 0.1% by weight based on the polymer (0.0036 molar ratio based on calcium carbonate).
Weight% ethylene glycol solution was added, and 10 minutes later, heated to 100 ° C., calcium carbonate having an average particle size of 0.5 μm was added.
50 parts by weight were added while maintaining the heating temperature of the ethylene glycol slurry containing 40% by weight. The temperature drop in the reaction system was small, and no sedimentation of particles at the bottom of the reaction vessel was observed. Next, 0.03 parts by weight of antimony trioxide was added as a polymerization catalyst.

Thereafter, a polycondensation reaction was carried out under a high temperature and reduced pressure according to a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity of 0.586 and a softening point of 259.9 ° C. As a result of observing the dispersion state of the polymer calcium carbonate particles, no aggregated particles were observed. The color tone of the obtained polymer was very high with a whiteness of 65.9, and the yellowish color was extremely small and good.

To 100 parts by weight of the obtained polyester, 0.03 parts by weight of a fluorescent brightener "OB-1" (manufactured by Eastman Co.) was blended, and biaxially stretched 3.2 times in length and 3.2 times in width according to a conventional method, and a 150 μm thick film. I got The resulting film had a density of 1.30, no defects such as air bubbles, and was excellent in whiteness and hiding power.

Comparative Example 1 Polyethylene terephthalate was obtained in the same manner as in Example 1 except that a calcium carbonate-containing ethylene glycol slurry at a temperature of 20 ° C. was used. When the ethylene glycol slurry containing calcium carbonate was added to the reaction system, the temperature in the system decreased significantly, and sedimentation of particles was observed at the bottom of the reactor. As a result of observing the dispersion state of calcium carbonate particles in the polymer, aggregated particles were observed in the polymer. Further, a film was produced from the polyester in the same manner as in Example 1. On the surface of the film, coarse projections appeared due to the aggregated particles, and the concealing power of the film was somewhat poor.

Examples 2 to 8, Comparative Examples 2 to 5 Example 1 except that the average particle size and amount of calcium carbonate added as described in Table 1, the heating temperature of the calcium carbonate-containing ethylene glycol slurry and the phosphorus compound were changed. A polyester and a film were produced in the same manner as in the above. Table 1 shows the results.

Examples 2 to 8 were within the scope of the present invention, and were excellent in both particle dispersibility and color tone, and the film obtained from the polyester was good in both whiteness and hiding power.

On the other hand, in Comparative Example 2, the heating temperature of the calcium carbonate-containing ethylene glycol slurry was out of the range of the present invention,
The film produced from the obtained polyester has poor concealing power and large film surface projections.

In Comparative Examples 3 and 4, the average particle size of calcium carbonate was out of the range of the present invention, and many agglomerated particles were observed in the obtained polyester, and the whiteness was low and the polymer was strongly yellowish. Films produced from the obtained polyester have disadvantages such as poor hiding power. In Comparative Example 5, the amount of calcium carbonate added was out of the range of the present invention, and the hiding power of the film was poor.

[Effect of the Invention] As described above, the present invention adds a specific amount of a phosphorus compound to a calcium carbonate-containing ethylene glycol slurry having an average particle size of 0.05 to 5 μ and a calcium carbonate heated at a specific temperature in a polyester reaction system. As a result, it is possible to obtain a large amount of a calcium carbonate-containing polyester containing no agglomerated particles and having high whiteness and little yellowish color, which has not been obtained conventionally, without impairing the productivity of the polyester.

When the polyester obtained by the production method of the present invention is formed into a film, reduction of clogging in a melt film forming step, prevention of bubbles during melt extrusion, and elimination of film breakage are, of course, excellent in whiteness and hiding power. White film can be manufactured, and is preferably used as a base material for photographic paper, X-ray intensifying screen, card, label, display board, white board, decorative use and the like.

Claims (1)

(57) [Claims] 1. A process for producing a polyester by reacting a dicarboxylic acid or an ester-forming derivative thereof with ethylene glycol at an optional stage of the polyester production process, wherein the ethylene glycol slurry is heated at a temperature of from 50 ° C. to less than the boiling point. 5 to 60% by weight based on the polyester from which calcium carbonate having an average particle size of 0.05 to 5 μ is obtained,
And a method for producing a polyester, comprising adding a phosphorus compound having a molar ratio to calcium carbonate of 0.0005 to 0.2 to the reaction system.