JPS6112726A - Preparation of polyester - Google Patents

Abstract

PURPOSE:To produce a polyester to be processed into fibers, films, etc. of extremely wide use, having improved mechanical properties such as strength, Young's modulus, etc., by adding an oxygenzoic acid oligomer during a production process of a polyester. CONSTITUTION:In production of a polyester by reacting a bifunctional carboxylic acid consisting essentially of terephthalic acid or its ester-forming derivative with at least one glycol or its ester-forming derivative to give a bifunctional carboxylic acid glycol ester and/or its low polymer, followed by subjecting the reaction product to polycondensation, >=0.01wt%, preferably 0.5-6 wt% compound shown by the formula (X is H, or acetyl; Y is H, or alkyl; n is average polymerization degree, >=2, preferably 4-12) is added to the polymerization system before the polycondensation reaction is finished.

Description

Detailed Description of the Invention (Technical Field) The present invention provides fibers with excellent mechanical properties such as strength and Young's modulus;
The present invention relates to a method for producing polyester that can produce films and the like.

(Technical background) Polyester in general, and polyethylene terephthalate in particular, has excellent mechanical, physical, and chemical properties;
It is widely used for clothing, industrial textiles, magnetic tape, photographic films, and other molded products.

However, in the field of textiles, polyester
With the improvement of productivity in post-processing and spinning processes, and the diversification of processes related to imparting oiliness to both long fibers and short m-fibers,
There is a growing demand for high quality, especially improved mechanical properties such as strength and Young's modulus.

In particular, there is a so-called direct spinning method that attempts to obtain a practical polyester IM using only the spinning process, which has been attracting particular attention in recent years, but in order to obtain the desired fiber with this method, at least the winding speed must be increased. It is necessary to achieve high speeds of 5,000 m/min or more, and even then,
Mechanical properties such as Young's modulus are still lower than those of ordinary drawn yarns, and improvements in this point are needed.

In addition, in the field of film, polyester is widely used as a base film for magnetic tapes due to its high strength and high Young's modulus as a biaxially stretched film. A thin base film is desired, and a film with high strength and high Young's modulus is also desired.

One of the inventors previously filed Japanese Patent Application No. 55-107753.

In Japanese Patent Application No. 55-116978, a manufacturing method was proposed in which a p-oxybenzoic acid monomer was added at the beginning of the polycondensation reaction of polyester.

However, polyester obtained by such a manufacturing method,
When subjected to high-speed spinning at a winding speed of 2,000 m/min or more,
The oriented crystallization that occurs during high-speed spinning can be suppressed, increasing the strength of the resulting spun yarn.

Young's modulus can be improved.

However, the strength and Young's modulus of the spun yarn obtained by subjecting such polyester to high-speed spinning, particularly at a winding speed of s, 000 m/min or more, are improved compared to those using conventional polyester. However, it is still not at a sufficient level and further improvements are desired.

(Object of the invention) The present invention has been made against the background of the above circumstances,
The object is to provide a highly versatile method for producing polyester that can produce fibers, films, etc. having improved mechanical properties such as strength and A7 rate.

(Structure of the Invention) As a result of studies to achieve the above object, the inventors found that p-
If a polyester obtained by adding oxybenzoic acid oligomer in the polyester manufacturing process is used, the strength and Young's modulus of the resulting spun yarn will be improved as shown in the examples below. The present invention was achieved by discovering that the polyester can be improved over polyester obtained by adding it in the process.

That is, the present invention provides a bifunctional carboxylic acid mainly consisting of terephthalic acid, or an ester-forming derivative thereof,
When producing a polyester by reacting at least one glycol or an ester-forming derivative thereof to produce a glycol ester of a difunctional carboxylic acid and/or a low polymer thereof, and then polycondensing the product, the following steps are performed: This is a method for producing polyester, characterized in that 0.01 wt% or more of the compound represented by the general formula [I] is added at any stage before the completion of the polycondensation reaction.

The polyester referred to in the present invention mainly refers to polyether consisting of a terephthalic acid component and a glycol component, particularly polyethylene terephthalate, but includes a portion of the terephthalic acid component (usually 15 mol% or less, preferably 10 mol%).
Even if it is a polyester in which a part of the glycol component (usually 1
It may also be a polyester in which 5 mol % or less, preferably 10 mol % or less) is replaced with other diol components. Furthermore, the polyester may be copolymerized or mixed with various additives such as an easy-to-dye agent, a flame retardant, an antistatic agent, a hydrophilic agent, a colorant, etc., if necessary.

Such polyesters are usually produced by subjecting terephthalic acid and glycol to an esterification reaction, or by subjecting a lower alkyl ester of terephthalic acid such as dimethyl terephthalate to a transesterification reaction with a glycol, or by reacting terephthalic acid and ethylene oxide. A first stage reaction to obtain a glycol ester of terephthalic acid and/or a low polymer thereof, followed by a second stage reaction to perform a deglycol reaction from a glycol ester of dicarboxylic acid or a low condensate thereof to obtain a high molecular weight polyester. reaction (polycondensation reaction).

In the present invention, it is important to add the compound represented by the general formula at any stage of the first and second stage reactions.

Examples of the compound include p-oxybenzoic acid oligomer and methyl p-oxybenzoic acid oligomer.

Examples include ethyl p-oxybenzoate oligomer, p-acetoxybenzoic acid oligomer, methyl p-acetoxybenzoate oligomer, and ethyl p-acetoxybenzoate oligomer.

If the average degree of polymerization n of these oligomers is 2 or more, the desired effects of the present invention can be achieved, and in particular, those with an average degree of polymerization n of 4 to 12 are preferable because they dissolve in the polymer and easily react with the polyester molecular chain. . If the average degree of polymerization n of such oligomers is too high, exceeding 12, it will not dissolve in the polymer, and the reactivity with the polyester molecular chain will be poor, resulting in little improvement in the strength and A7 rate of the resulting fibers and films. Moreover, it is likely to cause clogging of pack filters and the like during post-processing stages such as spinning and film forming.

As described in the examples below, p-
It is preferable to use oxybenzoic acid or methyl p-oxybenzoate, or p-acetoxybenzoic acid or methyl p-acetyl-oxybenzoate.

When p-oxybenzoic acid or methyl p-oxybenzoate is used as a starting material, water generated while heating under a xylene catalyst using a catalyst and p-1 toluenesulfonic acid is removed. Perform the reaction while Next, the precipitate separated out is washed with water and recrystallized with hot methanol to obtain the compound used in the present invention.

In addition, when p-acetoxybenzoic acid or methyl p-acetoxybenzoate is used as a starting material, the starting material is heated and dissolved under nitrogen pressure, and then the pressure is gradually reduced to remove the acetic acid generated. The compound used in the present invention can be obtained by carrying out the reaction.

In order to obtain a compound with a desired average degree of polymerization by such a method, there is a correlation between the amount of water or acetic acid distilled out by the reaction and the average degree of polymerization. If the relationship with the average degree of polymerization is investigated, the desired average degree of polymerization can be easily obtained by stopping the reaction when an amount of water or acetic acid has been distilled out to reach the desired average degree of polymerization.

In addition, the compound used in the present invention has an infrared spectroscopic analysis of 1
Since there are absorption peaks specific to 070 and 660cffl-1, it can be easily confirmed whether the compound obtained by the above method is the compound used in the present invention.

Furthermore, the average degree of polymerization of the obtained compound can also be confirmed by the amount of distilled water or acetic acid and the melting point, as described above.

It may be added at any stage during the polyester manufacturing process, but especially during the esterification reaction,
Alternatively, it is preferable to add the compound from the end of the transesterification reaction to the beginning of the polycondensation reaction in order to bond the compound into the polyester molecular chain and/or to the end of the molecular chain.

The amount of the compound added is 0.01 wt% or more, preferably 0.01 wt% or more.
．． The desired effect can be obtained at a content of 5 to 10 W[%, particularly preferably 0.5 to 5 wt%.

Then, when adding such an oligomer, p-A xybenzoic acid monomer and/or p-acetoxybenzoic acid monomer may be added together with the oligomer.

The polyester obtained by the production method of the present invention can be molded into fibers, films, and other molded products by conventional methods.

(Function) A p-oxybenzoic acid oligomer has a terminal group that easily reacts with a polyester molecular chain at one end thereof, and a terminal group that does not easily react with a polyester molecular chain at the other end. Moreover, such p-oxybenzoic acid oligomers also have good compatibility with polyesters.

In the production method of the present invention in which such a p-oxybenzoic acid oligomer is added during the polycondensation reaction, the reactivity between the p-oxybenzoic acid oligomer and the polyester molecular chain is considered to be good, and the resulting polyester It is presumed that p-oxybenzoic acid oligomer exists at the end of the polyester molecular chain.

For this reason, if such a polyester is used, crystallization due to rapid orientation of polyester molecular chains will occur during high-speed spinning where high shear forces are applied, as well as when using normal polyester. As a result, the strength and Young's modulus of the resulting fibers can be improved, as the strength and Young's modulus of the resulting fibers are suppressed more than when polyester obtained by adding only acid monomers is used.

Further, in a film using polyester obtained by the production method of the present invention, both strength and Young's modulus can be improved as in the case of fibers.

(Effect of the invention) When using the polyester obtained by the production method of the present invention,
Strength when molded into uA fiber, film, etc.

The effect of increasing Young's modulus can be obtained. Especially 5.0
When melt-spun at a high speed of 00 m/minute, it is possible to obtain fibers with high strength and Young's modulus comparable to fibers obtained by conventional spinning and drawing methods, without the need for a drawing process.

(Example) The present invention will be explained in more detail with examples.

Examples 1 to 7 (Synthesis of aromatic ester) A: p-oxybenzoic acid oligomer p-oxybenzoic acid I! t 276SF, a mixture of 138 g of ph luenesulfonic acid and 4000 g of xylene
The mixture was heated to 40° C. under reflux and the reaction proceeded while removing the generated water. After reacting for 5 hours, the precipitate was collected, washed with water, and recrystallized from hot methanol. Infrared spectroscopic analysis of the obtained oligomers revealed that 1070 and 660α-1
There was a characteristic absorption peak, and the average degree of polymerization was 6 based on the amount of distilled water and the melting point.

B: p-acetoxybenzoic acid oligomer 111,000 g of p-acetoxybenzoic acid was charged into a reactor and heated under nitrogen for 200 g.
Heat and dissolve at ℃. Then gradually reduce the pressure 60. H
Make it g. The reaction was carried out while gradually raising the reaction temperature while distilling off acetic acid. Infrared spectroscopic analysis of the obtained oligomer showed unique absorption peaks at 1070 and 660 cm-', and the average degree of polymerization was 2 based on the distilled amount of acetic acid and the melting point.

C: p-oxybenzoic acid methyl oligomer p-oxybenzoic acid monomer 304 g, p-1-luenesulfonic acid 13
8! A mixture of iF and 4000 g of xylene was heated under reflux at 140° C., and the reaction proceeded while removing the generated water. After reacting for 5 hours, the precipitate was collected, washed with water, and recrystallized from hot methanol. Infrared spectroscopic analysis of the obtained oligomer showed characteristic absorption peaks at 1070 and 660 cm-1, and the average degree of polymerization was 4 based on the amount of distilled water and the melting point.

D:])-Methyl aletoxybenzoate oligomer 1)-
1000 g of methyl acetoxybenzoate was charged into a reactor and dissolved by heating at 200° C. under nitrogen. The pressure is then gradually reduced to 60MnH9. The reaction was carried out while gradually raising the reaction temperature while distilling off acetic acid. Infrared spectroscopic analysis of the obtained oligomer showed 1070 and 660 cm-'
There was a characteristic absorption peak, and the average degree of polymerization was 12 based on the distilled amount of acetic acid and the melting point.

(Production of polymer) 970 parts of dimethyl terephthalate, 6 parts of ethylene glycol
40 parts and 0.3 manganese acetate as transesterification catalyst
One part (25 mmol % of dimemithi terephthalate) was charged into a reactor equipped with a stirrer, a rectification column, and a methanol distillation condenser, and heated from 140°C to 230°C, and the methanol produced as a result of the reaction was distilled out of the system. The transesterification reaction was carried out while allowing the reaction to proceed. Three hours after the start of the reaction, the temperature reached 230°C, and 320 parts of methanol was distilled out. At this time, 0.22 parts of tolumethyl phosphate (30 mmol% After adding dimethyl terephthalate) and reacting for 10 minutes, 0.44 part of antimony trioxide (dimethyl terephthalate) was added as a polycondensation catalyst.
The transesterification reaction was completed by adding 30 mmol % of dimethyl terephthalate) and the synthesized aromatic esters A to D in the amounts shown in Table 1.

Next, the obtained reaction product was transferred to a polycondensation reactor equipped with a stirrer and a glycol condenser, and heated from 230°C to 2°C.
While gradually raising the temperature to 85° C. and lowering the pressure from normal pressure to a high vacuum of 1 a Hg, a polycondensation reaction was carried out to obtain a polymer.

(Stretched Yarn) This polymer was spun at a spinning temperature of 285° C. and was discharged in an amount of 40 g per minute from a spinneret having 36 g of spinning holes with a diameter of 0.3 mm.

The undrawn yarn obtained by spinning at a winding speed of 800 TrL/min,
Stretching temperature: 83°C, stretching ratio: 3.5 times, stretching speed: 1000
A stretched system was obtained by stretching at m/min. Table 1 shows the Young's modulus 1 strength of this drawn yarn.

(High-speed spun yarn) Next, the same polymer was spun at a temperature of 290℃ and a diameter of 0.3mm.
The yarn is discharged from a spinneret having 36 spinning holes, and the linear velocity is 1.
Cooled with 3 TrL/min of cooling air (26°C, relative humidity 65%) and taken off at a spinning take-off speed of 6000 m/min.
I got a denier thread. Young's modulus of the obtained yarn.

The strength was as shown in Table 1.

(Film) Furthermore, using the same polymer, an unstretched original film was made at an extrusion temperature of 285°C, and a biaxially stretched film was made at a longitudinal stretch ratio of 3.5 times, a transverse stretch ratio of 4.0 times, and a film forming speed of 150 m/min. Created. The Young's modulus 1 strength of the obtained film was measured. The results are shown in Table 1.

Comparative Example 1 In Example 1, a polymer was obtained by performing a transesterification type 1 condensation reaction without adding an aromatic ester. Other conditions were the same as in Example 1. The results are shown in Table 1.

(Left below) Comparative Example 2 6.9 parts of p-oxybenzoic acid (instead of aromatic ester)
The same procedure as in Example 1 was carried out except that 1.0 mmol % of dimethic acid terephthalate) was added, and the results are shown in Table 2.

(The following is a blank space) Comparative Example 3 The same procedure as in Example 6 was carried out except that aromatic ester A was added after the polycondensation reaction was completed and the pressure was returned to normal pressure. The results are shown in Table 3.

(Margin below)

Claims (1)

[Claims] (1) A difunctional carboxylic acid consisting mainly of terephthalic acid, or its ester-forming derivative, and at least one glycol or its ester-forming derivative are reacted to produce a glycol ester of the difunctional carboxylic acid and/or its low-carbon derivative. When producing a polyester by forming a polymer and then polycondensing the product, the following general formula [
A method for producing a polyester, characterized in that 0.01 wt% or more of a compound represented by I] is added at any stage before the completion of a polycondensation reaction. ▲There are mathematical formulas, chemical formulas, tables, etc.▼Y...[I] [: Hydrogen atom or acetyl group Y: Hydrogen atom or alkyl group n: Indicates the average degree of polymerization, where n is 2 or more. ] (2) The average degree of polymerization n of the compound represented by the general formula [I] is 4 to
12. The method for producing polyester according to claim (1).