CN100457801C - Polybutylene terephthalate film and sheet and method for producing them - Google Patents

Abstract

Disclosed is a film or sheet made of a polybutylene terephthalate which is excellent in color tone, hydrolysis resistance, thermal stability, transparency, and formability. Extraneous substances included in such a film or sheet are reduced, and the polybutylene terephthalate contains not more than 100 ppm of a titanium compound as titanium atoms.

Description

Film and sheet made of polybutylene terephthalate and method for producing the same

technical field

The present invention relates to a film and a sheet containing polybutylene terephthalate whose color tone, hydrolysis resistance, thermal stability, transparency properties, formability and reduced impurities; more specifically, the present invention relates to a film and sheet containing polybutylene terephthalate capable of suppressing deterioration in quality even when subjected to a severe heating process.

Background technique

Among thermoplastic polyester resins, polybutylene terephthalate, as a representative engineering plastic, is easy to form and process, and its mechanical properties, heat resistance, chemical resistance, fragrance retention and other physical and chemical properties are relatively good. Excellent, so it is widely used in injection molded products such as automobile parts, electronic and electrical parts, and precision instrument parts. In recent years, taking advantage of its excellent properties, it has also begun to be widely used in fields such as films and sheets.

It is worth noting that, for films and sheets containing polybutylene terephthalate, during their manufacture, polybutylene terephthalate as a raw material is melted separately, or polybutylene terephthalate is used as a raw material Polybutylene terephthalate is produced by mixing it with other resins and melting it, and sometimes it is produced by melting it together with a colorant, a release agent, and a heat stabilizer. At this time, due to the influence of the heat process, the following problems occur, such as coloring, a decrease in mechanical strength with a decrease in molecular weight, generation of impurities (fish eyes), and an increase in the concentration of terminal carboxyl groups due to decomposition, etc., thereby reducing the commercial value.

In particular, when polybutylene terephthalate is mixed with polyester such as polyethylene terephthalate having a higher melting point than polybutylene terephthalate, polyamide, polyphenylene sulfide (polyphenylenesulphide) When mixing resins such as polycarbonate and polyphenylene ether with high melt viscosity to form films or sheets, higher temperature molding conditions have to be selected, and the above problems are even more severe.

Furthermore, when polybutylene terephthalate is used as a raw material to produce a film or sheet, in consideration of the requirements for reducing waste and reducing costs, it is sometimes necessary to cut the film or sheet to make the shape of the film or sheet. Parts (so-called "flabs") and defective parts of the product are recycled and used. At this time, since the heating process is further increased, the damage to the quality of the product becomes greater.

In addition, when producing polybutylene terephthalate, in many cases, a titanium compound is used as a catalyst, and the titanium compound remaining in the finally obtained polybutylene terephthalate will cause coloring and fish eye formation. , Increased terminal carboxyl groups and other issues.

On the other hand, the titanium catalyst added in the production of polybutylene terephthalate may be deactivated in the production of polybutylene terephthalate depending on the situation, although the deactivated titanium catalyst will not The increase in the terminal carboxyl group concentration of polybutylene terephthalate is promoted in the molding of films and sheets, but causes impurities and deterioration of transparency.

In order to overcome the above-mentioned problems, there is a proposal to use a filter installed during the polymerization process to remove the causative substance causing the fish eyes, thereby maintaining the fish eyes in the film at a certain amount or less (for example, refer to Patent Document 1).

However, even if the titanium catalyst and its residue used in the manufacture of polybutylene terephthalate are passed through a filter, most of it cannot be removed and directly enters the product. method cannot solve the above problems.

Patent Document 1: JP-A-2003-73488

Contents of the invention

The present invention is proposed in view of the above actual conditions, and its purpose is to provide a film or sheet containing polybutylene terephthalate, the color tone, hydrolysis resistance of the polybutylene terephthalate , Thermal stability, transparency, formability are excellent and impurities are reduced. In addition, it is still another object of the present invention to provide a method for producing a film or sheet containing polybutylene terephthalate which is stable even when subjected to a severe heating process. Quality reduction can be suppressed.

In order to solve the above-mentioned problems, the inventors of the present invention have made intensive studies and found that, by controlling the content of the titanium catalyst in polybutylene terephthalate and the activity of the titanium catalyst within a specific range, the problem can be easily solved. The above problems have been solved, and the present invention has been accomplished.

The present invention was accomplished based on the above findings, and its gist is that it is a film or sheet containing polybutylene terephthalate containing titanium and the titanium content is expressed as titanium The atomic basis is 100 ppm or less, and the activity parameter of the polybutylene terephthalate defined by the following formula (1) is 60 or less.

[mathematical formula 1]

d[COOH]/dt=k×[OH]×X (1)

In the formula (1), d[COOH]/dt represents the variation of the terminal carboxyl group concentration relative to time except for the hydrolysis reaction when the polybutylene terephthalate is kept at a certain temperature (T) under a nitrogen atmosphere, t For time (minutes), [COOH] is the terminal carboxyl concentration (μeq/g) of polybutylene terephthalate, [OH] represents the terminal hydroxyl concentration of polybutylene terephthalate (μeq/g ), k is a constant given by the following formula (2) as a function of temperature (T).

[mathematical formula 2]

log(k)＝log(A)-(ΔE/R)×(1/T) (2)

In formula (2), log is natural logarithm, A is a constant, log(A)=17.792, ΔE and R are constants, ΔE/R=13623.5, and T represents absolute temperature (K).

Another aspect of the present invention is that it is a film or sheet containing mixed polyester, in which polybutylene terephthalate and polyethylene terephthalate have a weight ratio of 1 :19 to 19:1 range for mixing.

Another aspect of the present invention is to provide a method for producing a film or sheet, the method is characterized in that it uses the above-mentioned recycled polyester as a raw material.

According to the present invention, there can be provided a film and sheet containing polybutylene terephthalate whose color tone, hydrolysis resistance, thermal stability, transparency, molding properties are excellent and impurities are reduced, and also, a method for producing a film or sheet containing polybutylene terephthalate that is stable even during severe heating can be provided. Quality reduction can be suppressed.

Description of drawings

FIG. 1 is an explanatory diagram of an example of an esterification reaction step or a transesterification reaction step used in the present invention.

Fig. 2 is an explanatory diagram of an example of a polycondensation step employed in the present invention.

FIG. 3 is an explanatory diagram of an esterification reaction step employed in Comparative Example 1. FIG.

Symbol Description:

1: Raw material supply line

2: Recycling line

3: Titanium catalyst supply line

4: Take out the line

5: Distillation line

6: Take out the line

7: Loop line

8: Take out the line

9: Gas take-out line

10: Condensate line

11: Take out the line

12: Loop line

13: Take out the line

14: Snorkel

15: Recycling line

A: Reaction tank

B: Take out the pump

C: Distillation tower

D, E: pump

F: tank

G: Condenser

L1, L3, L5: take out the line

L2, L4, L6: Vent lines

a: The first polycondensation reaction tank

d: The second polycondensation reaction tank

k: The third polycondensation reaction tank

c, e, m: gear pump for taking out

g: die head

h: rotary cutter

k: The third polycondensation reaction tank

Detailed ways

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below is a representative example of the embodiment of the present invention, but the present invention is not limited to these contents.

Polybutylene terephthalate (hereinafter referred to as PBT) in the present invention refers to the following polymer: it has a terephthalic acid unit and a 1,4-butanediol unit formed by an ester bond. structure; 50 mol% or more of dicarboxylic acid units are formed by terephthalic acid units; 50 mol% or more of diol units are formed by 1,4-butanediol units. The proportion of terephthalic acid units in all dicarboxylic acid units is preferably 70 mol% or more, more preferably 80 mol% or more, particularly preferably 95 mol% or more; 1,4-butanediol in all diol units The ratio of the unit is preferably 70 mol% or more, more preferably 80 mol% or more, particularly preferably 95 mol% or more. When the terephthalic acid unit or the 1,4-butanediol unit is less than 50 mol%, the crystallization rate of PBT will fall, and moldability will deteriorate.

In the present invention, dicarboxylic acid components other than terephthalic acid are not particularly limited, and examples thereof include phthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-diphenyl Ether dicarboxylic acid, 4,4'-benzophenone dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, 2,6-naphthalene Aromatic dicarboxylic acids such as dicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; Aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, etc. These dicarboxylic acid components can be introduced into the polymer skeleton in the form of dicarboxylic acid or in the form of dicarboxylic acid derivatives such as dicarboxylic acid esters and dicarboxylic acid halides as raw materials.

In the present invention, diol components other than 1,4-butanediol are not particularly limited. Examples include ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, polypropylene glycol, polytetramethylene glycol, dibutylene glycol, and 1,5-pentanediol , neopentyl glycol, 1,6-hexanediol, 1,8-octanediol and other aliphatic diols; 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanediol Alicyclic diols such as hexanedimethanol and 1,4-cyclohexanedimethanol, xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl) Propane, aromatic diols such as bis(4-hydroxyphenyl)sulfone, and the like.

In the present invention, the following components can be further used as copolymerization components: lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, p-β-hydroxyethoxybenzoic acid, etc. Hydroxy carboxylic acid, and alkoxy carboxylic acid, stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, tert-butyl benzoic acid, benzoyl benzoic acid and other monofunctional components; tricarboxylic acid, trimellitic acid , trimellitic acid, pyromellitic acid, gallic acid, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and other multifunctional components with more than three functional groups.

The PBT in the present invention is obtained by using 1,4-butanediol and terephthalic acid (or dialkyl terephthalate) as raw materials and using a titanium compound as a catalyst.

Specific examples of titanium catalysts include inorganic titanium compounds such as titanium oxide and titanium tetrachloride, titanium alkoxides such as tetramethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetraphenyl base titanate and other titanium phenoxides, etc. Among them, tetraalkyl titanate is preferable, and tetrabutyl titanate is preferable among tetraalkyl titanates.

Besides titanium, tin can also be used as catalyst. Tin is usually used as a tin compound, and specific examples of the tin compound can be enumerated such as: dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethyltin dioxide, cyclohexyltin dioxide, Dilauryl tin oxide, triethyl tin hydroxide, triphenyl tin hydroxide, triisobutyl tin acetate, dibutyl tin diacetate, diphenyl tin dilaurate, monobutyl tin trichloride, Tributyltin chloride, dibutyltin sulfide, butyltin oxyhydroxide, methylstannoic acid, ethylstannoic acid, butylstannoic acid, etc.

Since tin deteriorates the color tone of PBT, its addition amount is usually 200 ppm or less, preferably 100 ppm or less, and more preferably 10 ppm or less in terms of tin atoms, and it is preferable not to add it.

Moreover, in addition to titanium, the following substances can also be used: magnesium compounds such as magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, magnesium hydrogen phosphate; calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide, Calcium compounds such as calcium alkoxide and calcium hydrogen phosphate; antimony compounds such as antimony trioxide, germanium compounds such as germanium dioxide and germanium tetroxide, manganese compounds, zinc compounds, zirconium compounds, cobalt compounds, orthophosphoric acid, phosphorous acid , hypophosphorous acid, polyphosphoric acid, their esters or metal salts and other phosphorus compounds; sodium hydroxide, sodium benzoate and other reaction aids.

One of the characteristics of PBT in the present invention is that it contains titanium and the content of titanium is 100 ppm or less in terms of titanium atoms. The above numerical values are weight ratios of atoms to PBT. In addition, in the following description, ppm means weight basis.

In the present invention, the lower limit of the above-mentioned titanium content is usually 10ppm, preferably 15ppm, more preferably 20ppm, particularly preferably 25ppm; the upper limit is preferably 80ppm, more preferably 70ppm, further preferably 50ppm, particularly preferably 40ppm; wherein 33ppm is suitable. When the titanium content is too much, due to the heat experienced during the manufacture of films and sheets, it will lead to deterioration of the color tone and the deterioration of the hydrolysis resistance caused by the increase in the concentration of terminal carboxyl groups; and when the titanium content is too small, due to the polymerization of PBT As a result, the polymerization temperature needs to be increased, which leads to the deterioration of the color tone and the deterioration of the hydrolysis resistance.

The content of titanium atoms and the like can be measured by methods such as atomic emission, atomic absorption, and ICP (inductively coupled plasma) after recovering metals in the polymer by methods such as wet ashing.

Another feature of the PBT of the present invention is that the activity parameter X defined by the following formula (1) is 60 or less.

[mathematical formula 3]

d[COOH]/dt=k×[OH]×X (1)

In the formula (1), d[COOH]/dt represents the variation of the terminal carboxyl group concentration relative to time except for the hydrolysis reaction when PBT is kept at a certain temperature (T) under a nitrogen atmosphere, and t is time (minutes), [COOH ] is the terminal carboxyl group concentration (µeq/g) of PBT, and [OH] represents the terminal hydroxyl group concentration (µeq/g) of PBT. k is a constant given by the following formula (2) as a function of temperature (T).

[mathematical formula 4]

log(k)＝log(A)-(ΔE/R)×(1/T) (2)

In formula (2), log is natural logarithm, A is a constant, log(A)=17.792, ΔE and R are constants, ΔE/R=13623.5, and T represents absolute temperature (K).

In the present invention, the lower limit of the above-mentioned activity parameter X is usually 1, preferably 5, more preferably 10, especially preferably 15; the upper limit is preferably 50, more preferably 40, and particularly preferably 33. When the active parameter X is too large, due to the heat process during the manufacture of films and sheets, the color tone will deteriorate, and the hydrolysis resistance will deteriorate due to the increase in the concentration of terminal carboxyl groups; while the parameter is too small, due to the polymerization of PBT As a result, the polymerization temperature needs to be increased, which leads to the deterioration of the color tone and the deterioration of the hydrolysis resistance.

In the PBT of the present invention, α defined by the following formula (3) is preferably 0.80 or more.

[mathematical formula 5]

α＝X/[Ti]          (3)

In the formula (3), [Ti] is the titanium concentration (ppm) in the PBT, and X represents the activity parameter shown in the formula (1).

In the present invention, α is an index indicating the proportion of active titanium among titanium contained in PBT, and the higher the value of α, the less deactivation of the titanium catalyst. When the α value is less than 0.80, the haze of the film or sheet increases (transparency deteriorates), impurities increase, and the color tone deteriorates. The α value is preferably 0.85 or more, more preferably 0.90 or more, particularly preferably 0.95 or more.

In order to prevent the influence caused by oxygen, the evaluation of the terminal carboxyl group concentration relative to time is carried out under a nitrogen atmosphere; and if the water concentration in the evaluated PBT is high, hydrolysis reactions often occur, and it is difficult to accurately grasp the relationship between catalyst activity and Decomposition behavior unrelated to hydrolysis, therefore, is preferably carried out at a relatively low water concentration, usually 300 ppm or less. Furthermore, if the evaluation temperature (T) is too high, the increase rate of the terminal carboxyl group concentration is too large, and side reactions other than the terminal carboxyl group will occur concurrently, and the evaluation tends to become incorrect; on the contrary, if the evaluation temperature is too low, the terminal If the increase rate of the carboxyl group concentration is too small, the evaluation tends to be incorrect; therefore, an evaluation temperature of 503K to 523K (230°C to 250°C) is appropriate. In addition, if the evaluation time (heat treatment time) is too long or too short, the value may tend to be incorrect, so the upper limit of the evaluation time is generally 30 to 60 minutes, and it is recommended to acquire a large number of data over time. In this heat treatment condition, since the reduction in the number average molecular weight caused by reactions other than the hydrolysis reaction caused by the moisture contained in PBT can be ignored, it can be considered that the increase in the concentration of terminal carboxyl groups caused by the hydrolysis reaction is approximately Equal to the rising fraction of the terminal hydroxyl group concentration before and after heat treatment, therefore, the rising fraction of the terminal carboxyl group concentration caused by the thermal decomposition reaction other than the hydrolysis reaction can be obtained by the following formula (4):

[mathematical formula 6]

ΔAV(deg)=ΔAV(overall)-ΔAV(hyd)=ΔAV(overall)-ΔOH (4)

In the formula, ΔAV(deg) represents the change amount of terminal carboxyl group concentration caused by thermal decomposition reaction, ΔAV(overall) represents the overall change amount of terminal carboxyl group concentration before and after heat treatment, and ΔAV(hyd) represents the change amount of terminal carboxyl group concentration caused by hydrolysis reaction The amount of change, ΔOH represents the amount of change in the concentration of terminal hydroxyl groups before and after heat treatment.

The terminal carboxyl group concentration of PBT can be obtained by dissolving PBT in an organic solvent or the like and titrating with an alkaline solution such as sodium hydroxide to obtain the terminal carboxyl group concentration. In addition, the terminal hydroxyl group concentration can also be quantified by ¹ H-NMR.

The terminal carboxyl group concentration of PBT used in the film or sheet of the present invention is usually 0.1 μeq/g to 50 μeq/g, preferably 1 μeq/g to 40 μeq/g, more preferably 1 μeq/g to 30 μeq/g, particularly preferably 1μeq/g～25μeq/g. When the terminal carboxyl group concentration is too high, hydrolysis resistance will deteriorate.

Moreover, due to the heat process during film and sheet molding, the carboxyl end of PBT may tend to increase; on the other hand, if PBT is mixed with other resins with less carboxyl end, the film per unit weight , The terminal carboxyl group in the sheet may also decrease, and the terminal carboxyl group concentration of the film or sheet as the final product is usually 0.1μeq/g to 0.1μeq/g with respect to the film or sheet per unit weight including the weight of other resins 50 μeq/g, preferably 1 μeq/g to 40 μeq/g, more preferably 1 μeq/g to 30 μeq/g, particularly preferably 1 μeq/g to 25 μeq/g.

In addition, the terminal vinyl group concentration of the PBT of the present invention is usually 0.1 μeq/g to 15 μeq/g, preferably 0.5 μeq/g to 10 μeq/g, more preferably 1 μeq/g to 8 μeq/g. An excessively high concentration of terminal vinyl groups may cause color tone deterioration. Due to the heating process during molding, the concentration of terminal vinyl groups may have a tendency to further increase. In the case of high molding temperature, and in the case of manufacturing methods with recycling procedures, the deterioration of color tone will be more significant.

At the end of PBT, in addition to the hydroxyl group, carboxyl group, and vinyl group, the methoxycarbonyl group derived from the raw material remains. Especially when dimethyl terephthalate is used as the raw material, the methoxycarbonyl group may remain more. Methanol, formaldehyde, and formic acid are generated at the end of the methoxycarbonyl group due to heat during film and sheet molding, and the toxicity of these substances becomes a problem especially when used in food applications. Also, formic acid can cause damage to metal forming machines and vacuum-related machines attached to the machines. Therefore, the concentration of the terminal methoxycarbonyl group in the present invention is preferably 0.5 μeq/g or less, more preferably 0.3 μeq/g or less, particularly preferably 0.2 μeq/g or less, and the optimum value is 0.1 μeq/g or less.

The concentration of each of the above-mentioned terminal groups can be quantified by dissolving PBT in a mixed solvent of deuterated chloroform/hexafluoroisopropanol=7:3 (volume ratio), and measuring the concentration of each terminal group by ¹ H-NMR. groups were quantified. At this time, in order to prevent signal overlap with the solvent, a very small amount of basic components such as deuterated pyridine may be added.

In the present invention, the intrinsic viscosity of PBT is usually 0.6dL/g-2.5dL/g, preferably 0.8dL/g-2.0dL/g, more preferably 1.1dL/g-2.0dL/g, particularly preferably 1.2dL /g～1.5dL/g. When the intrinsic viscosity is less than 0.6dL/g, the mechanical strength of the molded product will be insufficient; if it exceeds 2.5dL/g, the melt viscosity will increase, the fluidity will deteriorate, and the moldability and surface properties of the product will tend to deteriorate. The above intrinsic viscosity is a value measured at 30° C. using a mixed solution of phenol/tetrachloroethane (weight ratio 1/1) as a solvent.

Among the present invention, the solution turbidity of PBT is not particularly limited, when 2.7 gram of PBT is dissolved in the mixed solution of the phenol/tetrachloroethane (weight ratio 3/2) of 20ml and measure, as its solution turbidity, Usually 10% or less, preferably 5% or less, more preferably 3% or less, particularly preferably 1% or less. When the turbidity of the solution is high, the transparency deteriorates and the impurities tend to increase, so that the transparency of the film or sheet deteriorates and the commercial value significantly decreases. In cases where the titanium catalyst is largely deactivated, the solution turbidity tends to increase.

Next, the manufacturing method of the PBT of this invention is demonstrated. The production method of PBT is roughly divided into a so-called direct polymerization method using a dicarboxylic acid as a main raw material and a transesterification method using a dicarboxylic acid dialkyl ester as a main raw material in terms of raw materials. The difference is that the former generates water in the initial esterification reaction, and the latter generates alcohol in the initial transesterification reaction.

In addition, the production method of PBT is roughly divided into a batch method (batch method) and a continuous method from the point of view of raw material supply or polymer take-out method. Some methods carry out the initial esterification reaction or transesterification reaction in a continuous operation mode, followed by polycondensation in a batch operation mode; on the contrary, there are also methods to perform the initial esterification reaction or transesterification reaction in a batch operation mode, Then polycondensation is carried out in a continuous operation mode.

In the present invention, the direct polymerization method is preferred from the viewpoints of raw material acquisition stability, ease of distillate treatment, high production efficiency, and the improvement effect of the present invention. In addition, in the present invention, it is preferable to adopt a method of continuously supplying raw materials and continuously performing esterification reaction or transesterification reaction from the viewpoints of productivity, stability of product quality, and improvement effect of the present invention. Therefore, in the present invention, a so-called continuous method in which the polycondensation reaction is carried out continuously after the esterification reaction or the transesterification reaction is preferable.

In the present invention, the following steps are preferably adopted: in the esterification reaction tank (or transesterification reaction tank), in the presence of a titanium catalyst, at least a part of 1,4-butanediol and terephthalic acid (or Dialkyl terephthalate) is independently supplied to the esterification reaction tank (or transesterification tank), while making terephthalic acid (or dialkyl terephthalate) and 1,4-butanedi Alcohols undergo esterification reaction (or transesterification) continuously.

That is to say, in the present invention, in order to reduce the turbidity and impurities caused by the catalyst without reducing the activity of the catalyst, as the raw material slurry or solution, in addition to being mixed with terephthalic acid or dialkyl terephthalate In addition to the supplied 1,4-butanediol, 1,4-butanediol and terephthalic acid or dialkyl terephthalate are separately supplied to an esterification reaction tank or a transesterification reaction tank. Hereinafter, this 1,4-butanediol may be referred to as "1,4-butanediol supplied separately".

The above-mentioned "1,4-butanediol to be supplied separately" may be fresh 1,4-butanediol regardless of the process. In addition, "1,4-butanediol supplied separately" may be supplied as 1,4-butanediol in the form of distilling 1,4-butanediol from an esterification reaction tank or a transesterification reaction tank Alcohol is collected by a condenser or the like and supplied as it is, or temporarily held in a tank and refluxed into a reaction tank to separate and purify impurities and supply it as 1,4-butanediol with increased purity. Hereinafter, "1,4-butanediol supplied separately" consisting of 1,4-butanediol collected by a condenser or the like may be referred to as "recycled 1,4-butanediol". From the viewpoint of efficient use of resources and simplicity of equipment, it is preferable to use "recycled 1,4-butanediol" as "1,4-butanediol to be supplied separately".

Usually, 1,4-butanediol distilled from an esterification reaction tank or a transesterification reaction tank contains components such as water, alcohol, THF, and dihydrofuran in addition to the 1,4-butanediol component. . Therefore, for the above-mentioned distilled 1,4-butanediol, it is preferable to separate it from water, alcohol, tetrahydrofuran and other components after being collected by the condenser, or while collecting it, and return it to the reaction after purification. groove.

In addition, in the present invention, it is preferable to directly return 10% by weight or more of the "1,4-butanediol supplied separately" to the reaction liquid liquid phase part. Here, the so-called "reaction liquid liquid phase part" means the liquid phase side of the gas-liquid interface in the esterification reaction tank or the transesterification reaction tank; 1,4-Butanediol" is directly supplied to the liquid phase part without passing through the gas phase part. The ratio of directly returning to the liquid phase of the reaction liquid is preferably 30% or more, more preferably 50% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more. When there is little "1,4-butanediol supplied separately" that is directly returned to the liquid phase of the reaction liquid, the titanium catalyst tends to be deactivated.

The temperature of "1,4-butanediol supplied separately" when returning to the reactor is usually 50°C to 220°C, preferably 100°C to 200°C, more preferably 150°C to 190°C. When the temperature of "1,4-butanediol supplied separately" is too high, the amount of THF by-products tends to increase; when the temperature is too low, energy loss may be incurred due to an increase in heat load.

In the present invention, in order to prevent deactivation of the catalyst, in the titanium catalyst used in the esterification reaction (or transesterification reaction), preferably 10% by weight or more of it is mixed with terephthalic acid (or dialkyl terephthalate) It is independently and directly supplied to the reaction liquid liquid phase part. Here, the "reaction liquid liquid phase part" means the liquid phase side of the gas-liquid interface in the esterification reaction tank or the transesterification reaction tank; The gas phase part of the reactor was directly fed to the liquid phase part. The proportion of the titanium catalyst directly added to the liquid phase portion of the reaction solution is preferably 30% by weight or more, more preferably 50% by weight or more, particularly preferably 80% by weight or more, most preferably 90% by weight or more.

The above-mentioned titanium catalyst may be dissolved in a solvent or the like, or directly supplied to the reaction liquid phase part of the esterification reaction tank or the transesterification reaction tank without dissolving it, but in order to stabilize the supply amount and reduce the amount caused by the reaction In order to avoid adverse effects such as denaturation caused by the heat of the heating medium sleeve of the device, it is preferable to dilute the titanium catalyst with a solvent such as 1,4-butanediol. The concentration of the titanium catalyst relative to the entire solution is usually 0.01% by weight to 20% by weight, preferably 0.05% by weight to 10% by weight, more preferably 0.08% by weight to 8% by weight. In addition, from the viewpoint of reducing impurities, the water concentration in the solution is usually 0.05% by weight to 1.0% by weight. From the viewpoint of preventing deactivation or aggregation, the temperature at the time of solution preparation is usually 20°C to 150°C, preferably 30°C to 100°C, more preferably 40°C to 80°C. In addition, the catalyst solution is preferably supplied to an esterification reaction tank or a transesterification reaction tank after being mixed with separately supplied 1,4-butanediol through piping or the like in consideration of prevention of deterioration, prevention of precipitation, and prevention of deactivation.

An example of the continuous method using the direct polymerization method is as follows. That is, the aforementioned dicarboxylic acid component mainly composed of terephthalic acid and the aforementioned diol component mainly composed of 1,4-butanediol are mixed in a raw material mixing tank to form a slurry; In an esterification reaction tank, in the presence of a titanium catalyst, at a temperature of usually 180°C to 260°C, preferably 200°C to 245°C, more preferably 210°C to 235°C, and at a temperature of usually 10kPa to 133kPa, preferably Under the pressure (absolute pressure, the same below) of 13kPa～101kPa, more preferably 60kPa～90kPa, carry out esterification reaction continuously in usually 0.5 hour～10 hours, preferably within the time of 1 hour～6 hours, obtain as The oligomer of the esterification reaction product is transferred to a polycondensation reaction tank, and in the presence of a polycondensation catalyst in one or more polycondensation reaction tanks, it is preferably at a temperature of usually 210°C to 280°C, preferably 220°C to 265°C, The polycondensation reaction is carried out continuously for usually 2 hours to 15 hours, preferably 3 hours to 10 hours, under a reduced pressure of usually 27 kPa or less, preferably 20 kPa or less, more preferably 13 kPa, with stirring. Usually, the polymer obtained by the polycondensation reaction is transferred from the bottom of the polycondensation reaction tank to the polymer take-out die, and made into a fiber (strand), which is cut with a cutter while water cooling or after water cooling, and made into pellets ( pellet), flakes (chip) and other granular bodies.

In the case of using the direct polymerization method, the molar ratio of terephthalic acid to 1,4-butanediol preferably satisfies the following formula (5):

[mathematical formula 7]

B/TPA＝1.1～5.0(mol/mol)        (5)

In the above formula, B is the number of moles of 1,4-butanediol supplied to the esterification reaction tank from the outside per unit time, and TPA is the number of moles of terephthalic acid supplied to the esterification reaction tank from the outside per unit time .

The above-mentioned "1,4-butanediol supplied from the outside to the esterification reaction tank" refers to 1,4-butanediol supplied simultaneously with terephthalic acid or dialkyl terephthalate as a raw material slurry or solution. -Butanediol and 1,4-butanediol supplied separately from these phases, 1,4-butanediol used as a solvent for the catalyst, etc. are added from the outside of the reaction tank to the 1,4-butanediol inside the reaction tank sum of alcohol.

When the above-mentioned B/TPA value is less than 1.1, the conversion rate decreases and the catalyst is deactivated; when the above-mentioned value exceeds 5.0, not only the thermal efficiency decreases, but also by-products such as tetrahydrofuran tend to increase in some cases. The value of B/TPA is preferably 1.5 to 4.5, more preferably 2.5 to 4.0, particularly preferably 3.1 to 3.8.

An example of the continuous method using the transesterification method is as follows. That is, in one or more transesterification reaction tanks, in the presence of a titanium catalyst, at a temperature of usually 110°C to 260°C, preferably 140°C to 245°C, more preferably 180°C to 220°C, and usually Under the pressure of 10kPa～133kPa, preferably 13kPa～120kPa, more preferably 60kPa～101kPa, carry out continuously the transesterification reaction that is usually 0.5 hour～5 hours, preferably 1 hour～3 hours, and the obtained product is produced as a transesterification reaction. The oligomer of the product is transferred to the polycondensation reaction tank, in one or more polycondensation reaction tanks, in the presence of a polycondensation reaction catalyst, preferably at a temperature of usually 210°C to 280°C, preferably 220°C to 265°C, usually 27kPa Below, preferably 20 kPa or less, more preferably 13 kPa, the polycondensation reaction is continuously carried out for usually 2 hours to 15 hours, preferably 3 hours to 10 hours, with stirring.

In the case of using the transesterification method, the molar ratio of dialkyl terephthalate to 1,4-butanediol preferably satisfies the following formula (6):

[mathematical formula 8]

B/DAT＝1.1～2.5(mol/mol)   (6)

In the above formula, B is the number of moles of 1,4-butanediol supplied to the transesterification tank from the outside per unit time, and DAT is the dialkyl terephthalic acid supplied to the transesterification tank from the outside per unit time. moles of ester.

When the above-mentioned B/DAT value is less than 1.1, the conversion rate decreases and the catalyst activity decreases; when the value exceeds 2.5, not only the thermal efficiency decreases, but also by-products such as tetrahydrofuran tend to increase in some cases. The value of B/DAT is preferably 1.1 to 1.8, more preferably 1.2 to 1.5.

In the present invention, in order to shorten the reaction time, the esterification reaction or the transesterification reaction is preferably carried out at a temperature equal to or higher than the boiling point of 1,4-butanediol. The boiling point of 1,4-butanediol varies with the reaction pressure, and is 230°C at 101.1kPa (atmospheric pressure), and 205°C at 50kPa.

As the esterification reaction tank or the transesterification reaction tank, known reaction tanks can be used, and any type such as a vertical stirring complete mixing tank, a vertical heat convection mixing tank, and a tower continuous reaction tank can be used. Moreover, it may be a single tank, or may be multiple tanks in which tanks of the same type or different types are connected in series or in parallel. Among them, a reaction tank with a stirring device is preferred; as the stirring device, in addition to the usual type composed of a power part, a bearing, a shaft, and a stirring blade, a turbine guide vane type high-speed rotating type mixer, a disc mixer, a rotor, etc. can also be used. High-speed rotary mixers such as rotor mill mixers.

The form of stirring is not particularly limited. In addition to the usual stirring method in which the reaction liquid in the reaction tank is directly stirred from the upper part, the lower part, and the horizontal part of the reaction tank, the following method can also be used: a part of the reaction liquid is mixed with a pipe or the like. It draws out to the exterior of a reactor, stirs with a linear stirrer etc., and circulates a reaction liquid.

The kind of agitating wing can be selected known kind, specifically, can enumerate such as propulsion propulsion wing, screw wing (screw), turbine wing, turbofan wing, turbine disk wing, three-blade backward curved (Pfaudler) wing, full area wing , Max Mixed Wing (Macksubrend) and so on.

In the manufacture of PBT, usually a plurality of reaction tanks are used, preferably 2 to 5 reaction tanks are used, and the molecular weight is increased sequentially. Usually, the polycondensation reaction is carried out after the initial esterification reaction or transesterification reaction.

In the polycondensation reaction step of PBT, a single reaction tank may be used, or a plurality of reaction tanks may be used. It is preferred to use a plurality of reaction tanks. The form of the reaction tank can be any form such as a vertical stirring complete mixing tank, a vertical heat convection mixing tank, a tower continuous reaction tank, or a combination of the above reaction tanks. Among them, a reaction tank with a stirring device is preferred. As the stirring device, in addition to the usual type composed of a power part, a bearing, a shaft, and a stirring blade, a turbine guide vane type high-speed rotating type mixer, a disc mixer, a rotor, etc. can also be used. High-speed rotary mixers such as grinding mixers.

The form of stirring is not particularly limited. In addition to the usual stirring method in which the reaction liquid in the reaction tank is directly stirred from the upper part, the lower part, and the horizontal part of the reaction tank, the following method can also be used: a part of the reaction liquid is mixed with a pipe or the like. It draws out to the exterior of a reactor, stirs with a linear stirrer etc., and circulates a reaction liquid. Among them, at least one of the polycondensation reaction tanks is recommended to use a horizontal reactor that has a rotation axis in the horizontal direction and is excellent in surface renewal and self-cleaning performance.

In order to suppress coloring, deterioration, and the increase of terminals such as vinyl groups, the reaction in at least one reaction tank is usually under a high vacuum of 1.3 kPa or less, preferably 0.5 kPa or less, and more preferably 0.3 kPa or less. 255°C, preferably 230°C to 250°C, more preferably 233°C to 245°C.

Furthermore, in the polycondensation reaction process of PBT, once PBT with a relatively small molecular weight, for example, an intrinsic viscosity of about 0.1 dL/g to 1.0 dL/g is produced by melt polycondensation, it can be made below the melting point of PBT. Solid state polycondensation (solid state polymerization) is carried out at a certain temperature.

In the PBT of the present invention, since the impurity derived from the catalyst has been significantly reduced, it is not necessary to remove the impurity; but by setting a filter on the polymer precursor or on the path of the polymer, the obtained polymer quality is even better. In the present invention, for the above reasons, in the case where a filter is used having the same pore size as that used in a manufacturing facility using PBT in the prior art, its life until exchange can be extended. In addition, if the lifetime until replacement is set to be the same, the pore diameter of the filter can be set to be smaller.

If the filter is installed at a position that is too upstream in the manufacturing process, the impurities generated on the downstream side cannot be removed; and if it is installed at a place with high viscosity on the downstream side, the pressure loss of the filter will increase. In order to maintain the flow rate, it is necessary to Increase the pore size of the filter or increase the filter area of the filter, piping and other equipment; moreover, due to the high shear force when the fluid flows through, the shear heat will inevitably deteriorate the PBT. Therefore, the installation position of the filter is selected so that the intrinsic viscosity of PBT or its precursor is usually 0.1dL/g～1.2dL/g, preferably 0.2dL/g～1.0dL/g, more preferably 0.5dL/g～ 0.9dL/g position.

Any of metal wire, laminated metal mesh, metal non-woven fabric, porous metal plate and the like may be used as the filter material constituting the filter. In consideration of filtration accuracy, laminated metal screens or metal non-woven fabrics are preferred, and it is particularly preferred to fix the pore size by sintering. As for the shape of the filter, any of basket type, disc type, vane type disc type, tube type, flat cylindrical type, folded cylindrical type, etc. may be used. Moreover, in order not to have an impact on the operation of the equipment, it is preferable to set a plurality of filters, which are configured to be switchable, or to set an automatic screen change device (auto screen change).

The absolute filtration accuracy of the filter is not particularly limited, and is usually 0.5 μm to 200 μm, preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, and particularly preferably 10 μm to 30 μm. If the absolute filtration precision is too large, the impurity reduction effect on the product will disappear; if it is too small, the production performance will decrease and the frequency of filter exchange will increase. The so-called absolute filtration accuracy refers to the minimum particle size that can be completely filtered out when using standard particle size products such as glass beads with known particle size and uniform particle size for filtration testing.

Next, preferred embodiments of the PBT manufacturing method will be described with reference to the drawings.

FIG. 1 is an explanatory diagram of an example of an esterification reaction step or a transesterification reaction step used in the present invention, and FIG. 2 is an explanatory diagram of an example of a polycondensation reaction step used in the present invention.

In Fig. 1, the raw material terephthalic acid is usually mixed with 1,4-butanediol in the raw material mixing tank (not shown in the figure), and supplied to the reaction tank in the form of slurry or liquid from the raw material supply line (1) (A). In addition, the titanium catalyst is preferably prepared as a 1,4-butanediol solution in a catalyst adjustment tank (not shown in the figure), and then supplied from the catalyst supply line (3). In FIG. 1 , the catalyst supply line ( 3 ) is connected to the recycling line ( 2 ) for recycling 1,4-butanediol, and after the two are mixed, they are supplied to the liquid phase portion of the reaction tank (A).

The gas distilled from the reaction tank (A) is separated into high boiling point components and low boiling point components in the rectification column (C) through the distillation line (5). Usually, the main component of the high-boiling point component is 1,4-butanediol, and the main components of the low-boiling point component are water and THF in the case of the direct polymerization method.

The high-boiling components separated in the rectification column (C) are taken out from the take-out line (6), and after passing through the pump (D), a part is recycled to the reaction tank (A) from the recirculation line (2), and a part is recycled from the recirculation line to the reaction tank (A). (7) Return to the rectification column (C). The remainder is taken out to the outside by the take-out line (8). In addition, the light boiling components separated by the rectification tower (C) are taken out from the gas extraction line (9), condensed in the condenser (G), and temporarily stored in the tank (F) through the condensate line (10). A part of the light boiling components collected in the tank (F) is returned to the rectification column (C) through the take-off line (11), the pump (E), and the circulation line (12), and the remaining material is taken out to the outside through the take-off line (13). The condenser (G) is connected with the exhaust device (not shown in the figure) through the ventilation line (14). The oligomers generated in the reaction tank (A) are taken out through the take-out pump (B) and the take-out line (4).

In the process shown in Figure 1, the catalyst supply line (3) is connected to the recirculation line (2), but the two can also be independent of each other. Furthermore, the raw material supply line (1) may be connected to the liquid phase part of the reaction tank (A).

In Figure 2, the oligomer supplied from the take-out line (4) shown in Figure 1 is polycondensed into a prepolymer in the first polycondensation reaction tank (a) under reduced pressure, and then the oligomer is taken out by the gear pump (c) And the take-out line (11) is supplied to the 2nd polycondensation reaction tank (d). In the second polycondensation reaction tank (d), further polycondensation is generally performed at a pressure lower than that in the first polycondensation reaction tank (a) to obtain a polymer. The obtained polymer was supplied to the 3rd polycondensation reaction tank (k) via the gear pump (e) for taking out and the taking out line (L3). The third polycondensation reaction tank (k) is composed of a plurality of blocks, and is a horizontal reaction tank having a biaxial self-cleaning stirring blade. After the polymer introduced from the second polycondensation reaction tank (d) to the third polycondensation reaction tank (k) through the take-out line (L3) is further polycondensed here, it is taken out through the gear pump (m) and the take-out line (15), It is taken out from the die (g) in the form of molten fibers. After cooling with water etc., cut with a rotary cutter (h) into pellets. Symbols ( L2 ), ( L4 ), and ( L6 ) represent ventilation lines of the first polycondensation reaction tank (a), the second polycondensation reaction tank (d), and the third polycondensation reaction tank (k), respectively.

In the PBT of the present invention, the following substances may also be added: 2,6-di-tert-butyl-4-octylphenol, pentaerythritol-tetra-[3-(3', 5'-tert-butyl-4' -Hydroxyphenyl)propionate] and other phenolic compounds; dilauryl-3,3'-thiodipropionate, pentaerythritol-tetrakis-(3-laurylthiodipropionate) and other thioethers Compounds; antioxidants such as triphenyl phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite and other phosphorus compounds; paraffin, microcrystalline paraffin, Polyethylene wax, long-chain fatty acids represented by montanic acid and montanic acid esters and their esters, silicone oil and other release agents.

A flame retardant may be added to the PBT of the present invention to impart flame retardancy. The flame retardant is not particularly limited, and examples thereof include organic halogen compounds, antimony compounds, phosphorus compounds, other organic flame retardants, and inorganic flame retardants. Examples of organic halogen compounds include brominated polycarbonate, brominated epoxy resin, brominated phenoxy resin, brominated polyphenylene ether resin, brominated polystyrene resin, brominated bisphenol A, polypentabromobenzyl Acrylic etc. Examples of antimony compounds include antimony trioxide, antimony pentoxide, and sodium antimonate. As a phosphorus compound, phosphoric acid ester, polyphosphoric acid, ammonium polyphosphate, red phosphorus etc. are mentioned, for example. Examples of other organic flame retardants include nitrogen compounds such as melamine and cyanuric acid. Examples of other inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, silicon compounds, boron compounds, and the like.

In the PBT of the present invention, commonly used additives can be blended as necessary. These additives are not particularly limited, and include, for example, stabilizers such as antioxidants and heat-resistant stabilizers, as well as lubricants, mold release agents, catalyst deactivators, crystal nucleating agents, and crystallization accelerators. These additives can be added during or after polymerization. Further, in order to impart desired performance to PBT, stabilizers such as ultraviolet absorbers and weather resistance stabilizers, colorants such as dyes and pigments, antistatic agents, foaming agents, plasticizers, impact modifiers, etc. may be added.

In the PBT of the present invention, polyethylene, polypropylene, polystyrene, polyacrylonitrile, polymethacrylate, ABS resin, polycarbonate, polyamide, polyphenylene sulfide, polyterephthalene, etc. Thermoplastic resins such as ethylene glycol formate, liquid crystal polyester, polyacetal, and polyphenylene ether, and thermosetting resins such as phenolic resins, melamine resins, silicone resins, and epoxy resins. These thermoplastic resins and thermosetting resins may be used in combination of two or more.

Among them, if PBT is used in combination with a resin having a higher melting point than the PBT used or a resin whose melt viscosity is higher than the PBT used, it is necessary to increase the molding temperature, so the improvement effect of the present invention is large. Specific examples of these resins include polyesters such as polyethylene terephthalate and polycyclohexane dimethylene terephthalate; polyhexamethylene adipamide (nylon 66 ); aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; polyamides such as semi-aromatic nylon in which diamines having an aromatic ring such as m-xylenediamine are used as part of the raw material; polyphenylene sulfide; polyphenylene ether; polycarbonate, etc. Among these, polyesters and polycarbonates are preferable, and polyethylene terephthalate is particularly preferable from the viewpoint of compatibility and mechanical properties. The mixing ratio of these resins and PBT is not particularly limited, and is usually 1/99 to 99/1 in terms of weight ratio, preferably 1/49 to 49/1, more preferably 1/19 to 19/1, and particularly preferably 1/9 to 1/9. 9/1.

The compounding method of the above-mentioned various additives and resins is not particularly limited, for example, using a single-screw or twin-screw extruder with a device capable of devolatilizing from the vent as a kneader, in the molding of films and sheets The method of pre-kneading into a mixture before processing; the method of dry mixing during the molding of films and sheets, etc. Each component including an additional component may be supplied to a kneader or a molding machine collectively, or may be supplied sequentially.

The color tone, hydrolysis resistance, thermal stability, transparency, and moldability of the film and sheet of the present invention are excellent, especially when the molding temperature is high and a production method with a recycling process is used, the improvement effect is remarkable . In the present invention, film and sheet both refer to a two-dimensionally expanded molded body with a critical thickness of 1/100 inch (0.254 mm). In PBT, there are many cases where the application is different depending on this thickness.

The method itself for producing the film and sheet of the present invention is not particularly limited, and various known methods can be employed. For example, after the PBT resin is dried, it is heated and melted by an extruder, extruded into a flat shape, and continuously extracted by a roller to make a T-die casting method of a flat film; the molten resin is continuously extruded from a ring die. , while adjusting the internal air pressure to make it expand into a balloon shape, the air-cooled expansion method is cooled naturally in the air or cooled by cold wind; the same is continuously extruded from the ring die, and the outer ring is controlled by a regular ring made of metal, etc. Diameter and add water to cool the water-cooled expansion method; the calendering method using rollers; the polishing roller method, etc. Furthermore, a multilayer film can be obtained using a known multilayering device (for example, a multi-manifold T-die, a laminate die, a feed combination die, a multilayer blow die) or the like.

In addition, a stretched film can also be obtained by uniaxial stretching or biaxial stretching by using a known method as needed. Biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. Furthermore, the dimensional stabilization treatment of the thin film may also be performed through a heat treatment step.

The manufacturing method of this invention is characterized by using the above-mentioned recovered product of PBT. That is, in the production method of the present invention, from the perspective of waste reduction, cost reduction, and the improvement effect of the present invention, the portion cut out to make the shape of the film and sheet (so-called stub portion), Parts that have no commercial value, such as defective parts of the product, are collected. At this time, the films and sheets can be recycled as described above; however, if these recycled films and sheets are considered to have a bad influence on the corrosivity of the feeder of raw materials and the screws of the molding machine, etc., there will be disadvantages in production. If appropriate, it can also be processed by granulation, cutting, crushing, etc.

The ratio of the recovered product in the raw material is usually 1% by weight to 50% by weight, preferably 1% by weight to 40% by weight, more preferably 1% by weight to 30% by weight. Although the above-mentioned PBT in the present invention is suitable for a production method having a recycling process, if the ratio of recycled products is too high, it may tend to cause deterioration of color tone, increase of impurities, and increase of terminal carboxyl group concentration.

Example

The following examples illustrate the present invention in more detail, as long as the gist of the present invention is not exceeded, the present invention is not limited to the following examples. In addition, the physical properties and measurement methods of evaluation items used in the following examples are as follows.

(1) Esterification rate

Calculated from the acid value and the saponification value according to the following calculation formula (7). The acid value was obtained by dissolving the oligomer in dimethylformamide and performing titration using a 0.1N KOH/methanol solution. The saponification value was obtained by hydrolyzing the oligomer with a 0.5N KOH/ethanol solution, followed by titration with 0.5N hydrochloric acid.

[mathematical formula 9]

Esterification rate = ((saponification value-acid value)/saponification value)×100 (7)

(2) Terminal carboxyl concentration

0.5 g of PBT or the oligomer was dissolved in 25 mL of benzyl alcohol, and titrated with a 0.01 mol/L benzyl alcohol solution of sodium hydroxide.

(3) Intrinsic viscosity (IV)

Obtained by the following steps using an Uber-Luther viscometer. That is, using a mixture of phenol/tetrachloroethane (weight ratio 1/1) as a solvent, the number of seconds to drop a polymer solution with a concentration of 1.0 g/dL at 30°C and the drop rate in the case of only the solvent were measured. The number of falling seconds can be obtained according to the following formula (8):

[mathematical formula 10]

IV=((1+4K _H η _sp ) ^0.5 -1)/(2K _H C) (8)

In the above formula, η _sp =η/η ₀ -1, η is the dripping seconds of the polymer solution, η ₀ is the dripping seconds of the solvent, C is the polymer solution concentration (g/dL), K _H is Huggins constant, K _H was adopted as 0.33.

(4) Titanium concentration in PBT

PBT was wet-decomposed with high-purity sulfuric acid and nitric acid for the electronics industry, and measured using high-resolution ICP (inductively coupled plasma)-MS (mass spectrometry) (manufactured by Thermokuest Corporation).

(5) Terminal methoxycarbonyl concentration and terminal vinyl concentration

Dissolve about 100 mg of PBT in 1 mL of a mixed solvent of deuterated chloroform/hexafluoroisopropanol=7/3 (volume ratio), add 36 μL of deuterated pyridine, and measure ¹ H-NMR at 50° C. to obtain the concentration. For the NMR apparatus, "α-400" or "AL-400" manufactured by JEOL Ltd. was used.

(6) Film forming and number of fish eyes

The PBT and polyethylene terephthalate pellets were dried in a nitrogen atmosphere at 120° C. for 8 hours, and a film with a thickness of 50 μm was obtained using a film forming machine (model ME-20/26V2) manufactured by Optical Control Systems. When there is only PBT in the system, set the temperature of the cylinder and die head to 250°C; when the system is a mixed system of PBT and polyethylene terephthalate, set the above temperature to 280°C. The number of fish eyes exceeding 200 μm per 1 m ² in the obtained film was measured using a film quality inspection system (manufactured by Optical Control System Co., Ltd., model FS-5).

Table 1

○: Number of fish eyes <20

△: The number of fish eyes is 20 to 100

×: Number of fish eyes > 100

(7) Film properties:

Tensile properties of 50 micron films were evaluated according to ASTM D-882. In particular, the tensile elongation at break (%) was used as an evaluation criterion for deterioration.

(8) Turbidity of solution:

After dissolving 2.70 g of PBT in a mixture of 20 mL of phenol/tetrachloroethane=3/2 (weight ratio) at 100° C. for 30 minutes, cool in a constant temperature water tank at 30° C. for 15 minutes, and use Nippon Denshoku Co., Ltd. ) with a turbidity meter (NDH-300A) manufactured in , and measured with a test dish (cell) length of 10 mm. Lower numbers indicate better transparency.

(9) Calculation of catalyst activity parameter (X):

The PBT pellets were pulverized, dried, and filled into five capillary tubes with an inner diameter of 5 mm. Next, after the contents were sufficiently replaced with nitrogen, the capillary was immersed in an oil bath precisely controlled at 245° C., taken out over time with an upper limit of 60 minutes, and rapidly cooled in liquid nitrogen. Then, the contents were taken out, and the terminal carboxyl group concentration and the terminal hydroxyl group concentration were determined. Using these numerical values, X is obtained from the aforementioned formula (1) and formula (2).

(10) Grainy shades

Using a color difference meter (Z-300A type) manufactured by Nippon Denshoku Co., Ltd., the b value in the L, a, and b color system was calculated and evaluated. Lower values indicate less yellowing and a better tone.

(11) Film tint

Using a color difference meter (Z-300A) manufactured by Nippon Denshoku Co., Ltd., the b value in the L, a, and b color system was calculated and evaluated. A lower value indicates a better tone with less yellowing.

(12) Formaldehyde production

1 g of PBT and 5 mL of hydrochloric acid aqueous solution adjusted to pH 2.29 were put into a 10 mL headspace analysis bottle, and stirred and extracted at 120° C. for 1 hour. After cooling the solution, it was filtered through a chromatographic disc. Further accurately weigh about 3 g of this solution, add 0.2 mL of 0.25% 2,4-dinitrophenylhydrazine-6N hydrochloric acid solution and 1 mL of hexane, react at 50 ° C for 20 minutes, and use a gas spectrometer (manufactured by Shimadzu Corporation) The "GC2010" and the column "HP-5MS" were used to analyze the hexane phase.

Example 1

Through the esterification step shown in FIG. 1 and the polycondensation step shown in FIG. 2 , PBT was produced in the following manner. First, mix terephthalic acid and 1,4-butanediol at a ratio of 1.00 moles of terephthalic acid and 1.80 moles of 1,4-butanediol to form a slurry at 60°C, and prepare the slurry from Tank is continuously supplied to the reaction tank (A) that is used for esterification with the mode of 41kg/h by raw material supply line (1), and this reaction tank (A) is filled with the PBT oligomer of esterification rate 99% in advance, And has a screw mixer. At the same time, the bottom component of the rectification column (C) at 185° C. is supplied at 17.2 kg/h from the recirculation line (2), and tetrabutyl at 65° C. is supplied as a catalyst at 97 g/h from the catalyst supply line (3). 6.0% by weight titanate solution in 1,4-butanediol (relative to the theoretical polymer yield, the catalyst is 30 ppm in terms of titanium atoms). The water content in this solution was 0.20% by weight.

The internal temperature of reaction tank (A) is set as 230 ℃, pressure is set as 78kPa, the water and tetrahydrofuran (THF) and remaining 1,4-butanediol distilled from distillation line (5) of generation, in rectification tower ( C) Separation into high boiling point components and low boiling point components. After the system is stabilized, more than 98% by weight of the high boiling point components at the bottom of the column is 1,4-butanediol, and part of it is taken out through the take-off line (8) to keep the liquid level of the rectification column (C) constant. On the other hand, low boiling point components are taken out in a gaseous state at the top of the column, condensed in the condenser (G), and taken out from the takeout line (13) to the outside to keep the liquid level of the tank (F) constant.

A certain amount of oligomer produced in the reaction tank (A) was taken out from the take-out line (4) by using a pump (B), and the liquid level was controlled so that the average residence time of the liquid in the reaction tank (A) was 3.3 hr. The oligomer taken out from the take-out line 4 is continuously supplied to the first polycondensation reaction tank (a). After the system was stabilized, the esterification rate of the oligomer sampled at the outlet of the reaction tank (A) was 97.5%.

The internal temperature of the first polycondensation reaction tank (a) was set to 240° C., the pressure was set to 2.1 kPa, and the liquid level was controlled so that the residence time would be 120 minutes. The initial polycondensation reaction was carried out while taking out water, tetrahydrofuran, and 1,4-butanediol from a vent line (L2) connected to a pressure reducer (not shown in the figure). The reaction liquid taken out was continuously supplied to the 2nd polycondensation reaction tank (d).

The inner temperature of the 2nd polycondensation reaction tank (d) is set to 245° C., the pressure is set to 130 Pa, the liquid level is controlled so that the residence time is 90 minutes, and the depressurizer (not shown) is connected to it. Water, tetrahydrofuran, and 1,4-butanediol were taken out from the gas line (L4) of the gas flow line (L4), and the polycondensation reaction was further carried out. The obtained polymer was continuously supplied to the 3rd polycondensation reaction tank (k) via the take-out line (L3) by the gear pump (e) for take-out. The inner temperature of the third polycondensation reaction tank (k) was set to 240° C., the pressure was set to 130 Pa, and the residence time was set to 60 minutes. The obtained polymer was continuously taken out from the die (g) in the form of fibers via a gear pump (m) and a take-out line (L5), and cut by a rotary cutter.

The IV of the obtained PBT was 1.20 dL/g, the Ti content was 30 ppm, and the catalyst activity parameter was 30. Using this PBT, a film was molded by the method described above, and evaluated. A good film with a low concentration of terminal carboxyl groups, few fish eyes, and excellent mechanical properties and color tone was obtained after being formed into a film. The results are summarized in Table 2.

Example 2

Except that the supply rate of the catalyst solution in Example 1 is set to 130g/h, and the pressure of the third polycondensation reaction tank (k) is set to 150Pa, all the other operations are the same as in Example 1, and the obtained IV is 1.20dL /g, PBT particles with a Ti content of 40ppm and a catalyst activity parameter of 40. Using this PBT, a film was molded and evaluated by the method described above. A good film with a low concentration of terminal carboxyl groups, few fish eyes, and excellent mechanical properties and color tone was obtained after being formed into a film. The results are summarized in Table 2.

Example 3

Except that the internal temperature of the third polycondensation reaction tank (k) in Example 1 was set to 244°C and the residence time was set to 90 minutes, the rest were performed in the same manner as in Example 1, and an IV of 1.30 dL/g was obtained. , PBT particles with a Ti content of 30ppm and a catalyst activity parameter of 30. Using this PBT, a film was molded by the method described above, and evaluated. A good film with a low concentration of terminal carboxyl groups, few fish eyes, and excellent mechanical properties and color tone was obtained after being formed into a film. The results are summarized in Table 2.

Example 4

In addition to setting the supply rate of the catalyst solution in Example 1 to 245 g/h, the supply rate of the bottom component of the rectification column (C) to 10.0 kg/h, and the second polycondensation reaction tank (d) Temperature is set as 243 ℃, the pressure of the 3rd polycondensation reaction tank (k) is set as 140Pa except, all the other are all operated in the same way as Example 1, obtained IV is 1.20dL/g, Ti content is 75ppm, catalyst activity parameter is 45 PBT pellets. Using this PBT, a film was molded by the method described above, and evaluated. A good film with a low concentration of terminal carboxyl groups, few fish eyes, and excellent mechanical properties and color tone was obtained after being formed into a film. The results are summarized in Table 2.

Example 5

Using 70 parts by weight of the PBT of Example 1 and 30 parts by weight of polyethylene terephthalate ("Nobapex GS385" manufactured by Mitsubishi Chemical Corporation), a film was molded at 280° C. and evaluated. A good film with a low concentration of terminal carboxyl groups, few fish eyes, and excellent mechanical properties and color tone was obtained after being formed into a film at high temperature. The results are summarized in Table 2.

Comparative example 1

Using the esterification process shown in Figure 3, the bottom component of the rectification column (C) is supplied through the gas phase part of the esterification reaction tank (A) using the line (15), and is supplied from the catalyst that merges with the raw material supply line (1). The esterification reaction was carried out in the same manner as in Example 1 except that the catalyst solution was supplied at 357 g/h to the line (3). In the subsequent polycondensation step, in addition to setting the internal temperature of the second polycondensation reaction tank (d) to 243°C, the residence time to 60 minutes, the internal temperature of the third polycondensation reaction tank to 241°C, and the residence time The time was set to other than 60 minutes, and the polycondensation reaction was carried out in the same manner as in Example 1 for the rest. Next, the same operation as in Example 1 was carried out to obtain PBT particles with an IV of 1.20 dL/g, a Ti content of 110 ppm, and a catalyst activity parameter of 80. Using this PBT, a film was molded by the method described above, and evaluated. The concentration of terminal carboxyl groups increased greatly before and after film forming, resulting in many fish eyes and poor color tone. The results are summarized in Table 3.

Comparative example 2

In addition to setting the supply rate of the catalyst solution in Example 1 to 490 g/h, the supply rate of the bottom component of the rectification column (C) to 3.0 kg/h, and the residence time of the second polycondensation reaction tank to For 60 minutes, the pressure of the 3rd polycondensation reaction tank was set to 140Pa, all the others were operated in the same manner as in Example 1, and obtained IV was 1.20dL/g, Ti content was 150ppm, and the catalyst activity parameter was 55 PBT particles. Using the PBT pellets, a film was formed by the method described above, and evaluated. The concentration of terminal carboxyl groups increased greatly before and after film forming, resulting in many fish eyes and poor color tone. The results are summarized in Table 3.

Comparative example 3

Using 70 parts by weight of PBT of Comparative Example 1, a film was formed and evaluated in the same manner as in Example 5. Since it is formed into a film at high temperature, the concentration of terminal carboxyl groups increases greatly before and after film forming, resulting in many fish eyes and poor mechanical properties and color tone. The results are summarized in Table 3.

Comparative example 4

Add 272.9 mol dimethyl terephthalate (DMT), 327.5 mol 1,4-butanediol, 0.139 mol tetrabutyl titanate to a stainless steel reaction vessel with a turbine-type stirring blade and an inner volume of 200 L (The amount of titanium is 110 ppm relative to the theoretical yield of the polymer), and the nitrogen substitution was sufficiently performed. Next, the system was heated up, and after 60 minutes, at a temperature of 210° C., under a nitrogen atmosphere, methanol, 1,4-butanediol, and THF were distilled out of the system while carrying out a 2-hour transesterification reaction ( The reaction start time is the time when the predetermined temperature and predetermined pressure are reached).

The oligomer obtained above was transferred to a stainless steel reactor with an internal volume of 200 L having a vent tube and a double-helical stirring blade, and the temperature was raised to 245° C. and the pressure to 100 Pa over 60 minutes, and the process was carried out while maintaining this state. 1.5 hours of polycondensation reaction. After the reaction, the polymer was taken out in the form of fibers and cut into pellets. The thus-obtained PBT pellets were placed in a dual-core type sleeved solid-phase polymerization apparatus having an inner volume of 100 L, and depressurization/nitrogen replacement was repeated three times. Next, the pressure was controlled at 130 Pa, the temperature was raised to 200° C., samples were taken over time, and the IV value was measured. The solid phase polymerization was terminated when the IV value finally reached 1.20. The amount of formaldehyde generated from this PBT was 0.8 ppm. Evaluation was performed using the thus obtained PBT molded film having an average IV of 1.20 dL/g and a titanium content of 110 ppm. The obtained film had a large ΔAV (increase in terminal carboxyl group concentration before and after molding) during molding, a large number of fish eyes, and poor appearance. The results are summarized in Table 3.

Example 6

70 parts by weight of the PBT used in Example 1 was mixed with 30 parts by weight of the pulverized dry product of the film (R0) obtained in Example 1, and a film was formed in the same manner as in Example 1. Next, 30 parts by weight of the film (R1) of the recycled product added at one time was mixed with 70 parts by weight of the PBT used in Example 1, and a film (R2) was formed in the same manner as in Example 1. This operation was repeated to obtain a thin film (R4) in which recycled materials were added three times. Although the operation of mixing recovered products was repeated in this way, the increase in the terminal carboxyl group concentration was small, and a PBT film with good quality was obtained. The results are summarized in Table 4.

Comparative Example 5

Using the PBT of Comparative Example 1, a film (R4) in which recyclates were added three times was obtained in the same manner as in Example 6. The obtained film had a large increase in the terminal carboxyl group concentration, a large number of fish eyes, and poor color tone and strength. The results are summarized in Table 4.

Table 2

table 3

Table 4

Claims (13)

1, a kind of film or sheet material that contains polybutylene terephthalate, wherein, the content that described polybutylene terephthalate contains titanium and this titanium is counted below the 100ppm with titanium atom, the intrinsic viscosity of described polybutylene terephthalate is 1.1dL/g～2.0dL/g, and this polybutylene terephthalate is below 60 with the reactivity parameter X of following formula (1) defined:

d[COOH]/dt＝k×[OH]×X (1)

In the formula (1), d[COOH]/variable quantity of end carboxy concentration relative time when dt represents that polybutylene terephthalate remained in certain temperature T under nitrogen atmosphere except that the hydrolysis reaction, t is the time, its unit is minute, [COOH] is the end carboxy concentration of polybutylene terephthalate, and its unit is μ eq/g, the terminal hydroxyl concentration of [OH] expression polybutylene terephthalate, its unit is μ eq/g, the constant that k provides for the following formula (2) as the function of temperature T:

log(k)＝log(A)-(ΔE/R)×(1/T)(2)

In the formula (2), log is a natural logarithm, and A is a constant, and log (A)=17.792, Δ E and R are constant, Δ E/R=13623.5, and T represents absolute temperature, its unit is K.

2, film as claimed in claim 1 or sheet material, the titanium content of wherein said polybutylene terephthalate is counted below the 70ppm with titanium atom.

3, film as claimed in claim 1 or 2 or sheet material, the reactivity parameter X of wherein said polybutylene terephthalate is below 40.

4, film as claimed in claim 1 or 2 or sheet material, the terminal methoxycarbonyl concentration of wherein said polybutylene terephthalate is below the 0.5 μ eq/g.

5, film as claimed in claim 1 or 2 or sheet material, wherein said polybutylene terephthalate is more than 0.80 by the α value of following formula (3) defined:

α＝X/[Ti](3)

In the formula (3), [Ti] is the titanium concentration in the polybutylene terephthalate, and its unit is ppm, the defined reactivity parameter of X expression (1).

6, film as claimed in claim 1 or 2 or sheet material, the end carboxy concentration of wherein said polybutylene terephthalate are 1 μ eq/g～30 μ eq/g.

7, film as claimed in claim 1 or 2 or sheet material, the terminal ethylenyl groups concentration of wherein said polybutylene terephthalate are 0.5 μ eq/g～10 μ eq/g.

8, film as claimed in claim 1 or 2 or sheet material, wherein the polybutylene terephthalate of 2.7g is dissolved in when measuring in phenol/tetrachloroethane mixed solvent of 20mL, the solution turbidity of polybutylene terephthalate is below 10%, in described phenol/tetrachloroethane mixed solvent, the weight ratio of described phenol and tetrachloroethane is 3/2.

9, film as claimed in claim 1 or 2 or sheet material, wherein said polybutylene terephthalate are to obtain with the manufacture method that comprises the continuous esterification operation that adopts the direct polymerization method.

10, a kind of film or sheet material, it contains mixed polyester, and in the described mixed polyester, any described polybutylene terephthalate of claim 1～9 and polyethylene terephthalate are that 1: 19～19: 1 scope is mixed with weight ratio.

11, film as claimed in claim 10 or sheet material, wherein said polybutylene terephthalate are to obtain with the manufacture method that comprises the continuous esterification operation that adopts the direct polymerization method.

12, the manufacture method of a kind of film or sheet material is characterized in that, its recovery article that uses any described polyester of claim 1～11 is as raw material.

13, manufacture method as claimed in claim 12, wherein the ratio of recovery article is 1 weight %～50 weight %.

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