JPH04309520A - Production of copolyester - Google Patents

Abstract

PURPOSE:To produce a copolyester improved in strengths, breaking strength, heat resistance, etc., by reacting two specified compounds with a dicarboxylic acid and acetic anhydride and polycondensing the reaction product in a molten state. CONSTITUTION:A compound of formula I is made to react with a dicarboxylic acid of formula II and compounds of formulas III and/or IV and acetic anhydride, and the product is polycondensed at 280 deg.C or below in a molten state to obtain a liquid crystal copolyester comprising dicarboxylic acid units of formula V (wherein R<1> is a 6-18C bivalent aromatic hydrocarbon group), diol units of the formula: OCH2CH2O, and oxybenzoic acid units of formula V1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing liquid crystalline polyester in which the sequence is controlled more alternately. The liquid crystalline polyester of the present invention is
It has a high modulus of elasticity, high tensile strength, bending strength, impact strength, etc., and has high elongation, so it has toughness, and with the same composition and composition ratio, it not only has better mechanical properties than conventional products. It also has excellent heat resistance.

The liquid crystalline polyester of the present invention can exhibit these characteristics because it forms thermotropic liquid crystals during molding and the sequence is more alternatingly controlled. It also has the characteristic of exhibiting high fluidity even at lower temperatures than conventional products with the same composition and composition ratio. Therefore, it is very useful as products such as molding materials, films, and fibers.

[0003] In particular, it is suitable as a molding material for automobile parts, electric and electronic parts, thin molded products, and precision molded products. Furthermore, since the difference between the solid heat resistance temperature and the temperature at which it can be sufficiently melted is small, it has the advantage in terms of polymerization that it can be polymerized at a low temperature despite its high heat resistance.

0004

BACKGROUND OF THE INVENTION In recent years, there has been an increasing demand for materials with excellent rigidity, strength, elongation, and heat resistance, regardless of whether they are fibers, films, or molded products. Polyester has come to be widely accepted for use in general molded products, but many polyesters have poor flexural modulus and bending strength, so they are not suitable for applications that require high modulus of elasticity and high strength. In recent years, liquid crystalline polyester has attracted attention as a polyester suitable for applications requiring high elastic modulus and high strength. The Journal of Polymer Science Polymer Chemistry Edition Vol. 14 (1976) 2043 has attracted particular attention.
Page, USP 3,778,410, USP 3,804,8
05 and Japanese Patent Publication No. 56-18016. J. This was after Jackson et al. announced a thermal liquid crystal polymer consisting of polyethylene terephthalate and acetoxybenzoic acid. Jackson et al. found that this liquid crystal polymer has more than five times the rigidity and four times the strength of polyethylene terephthalate.
It was reported that the impact strength was 25 times higher, demonstrating new possibilities for high-performance resins.

However, the polymer proposed by Jackson et al. had the disadvantage of being extremely brittle and having low strength and elongation. This is thought to be mainly due to the extremely large proportion of chains of p-oxybenzoic acid residues represented by the following formula (13).

[C5]

[0006] Furthermore, it is thought that the melting point, softening point, etc. vary depending on the ratio of (13). On the other hand, there are many reports examining molding processing conditions using this Jackson et al. polymer. (For example, J.A. Cuculo et al., Jou
rnal of Polymer Science
e. Physical Edition 26
179 (1988)) According to this report, the higher the molding temperature, the higher the elastic modulus, and the reason for this is that unmelted materials exist at low temperatures and cause defects in the higher-order structure of the molded product. It is said that (This shows that it is only partially in a liquid crystal state.)

[0007] This is considered to be because the sequences and their distribution as well as the composition distribution are distributed over a wide range, that is, they are highly heterogeneous. This means that unless the molding temperature is high compared to the heat resistance of the solid, it will not be possible to develop high-performance physical properties. In other words, the fluidity deteriorates near the melting start point and a temperature slightly higher than that point, and it becomes impossible to form thin objects, which is a characteristic of liquid crystalline polymers.

The present applicants had previously discovered a copolymerized polyester that improved the elongation at break of the polyester developed by Jackson et al.
. The idea here is to reduce the above (13), which is a chain of p-oxybenzoic acid units, and this is the origin of the attempt to reduce (13). however,
The manufacturing method in JP-A-60-186527 and JP-A-60-1
According to the manufacturing method of No. 86525, although efforts were made to prevent p-oxybenzoic acid from being linked at the beginning, only a random polymer was produced, and the elongation at break was much lower.
In addition, there was a large difference between the temperature at which it could maintain heat resistance when solid and the temperature at which it could flow sufficiently.

According to JP-A No. 64-26632, the liquid crystalline polyester obtained by the method of Jackson et al. is a highly blocky polymer ((( Since the formation of a high fraction of 13) deteriorates the physical properties and other properties, randomization was carried out using a two-step polymerization method, thereby improving the physical properties.

[0010] However, additional testing of the polyester produced by this method revealed that although it had high heat resistance, it had a high melt viscosity, had considerably poor fluidity, and had poor mechanical properties such as strength and elongation. As mentioned above, this is p-
This is probably due to the fact that oxybenzoic acid is polymerized only randomly.

Furthermore, although JP-A-2-45524 attempts to improve the process by adding p-hydroxybenzoic acid and acetic anhydride or p-acetoxybenzoic acid continuously or in portions,

When the ratio of [Chemical 6] is 80:20 (molar ratio), HDT is 150
℃ only, and the melt viscosity at 318° C. was 770 poise, which was inferior to the method according to JP-A-64-26632. (Refer to the description of Example 1 in JP-A-2-45524)

Furthermore, we have discovered a copolyester that suppresses the formation of insoluble and infusible particles. (Unexamined Japanese Patent Publication No. 62-41
(No. 221) However, this polyester sometimes has poor heat resistance and is sometimes unsuitable for engineering plastics. Also, USP 3,890
, 256 discloses a polyester that improves abrasion resistance, but this polyester was also published in Japanese Patent Publication No. 56-1801.
Due to the same method as No. 6,

A chain of [Chemical 7] was likely to be formed. Therefore, insoluble/infusible particles are likely to be formed, and the resulting polymer tends to have a lower elongation at break and become brittle.

[0013] Furthermore, because the copolymerization component is too large, the heat resistance is often poor. Furthermore, according to the above-mentioned patent USP 3,804,805 by Jackson et al.

There is an example of using [Chemical formula 8], but additional tests show that the heat resistance is poor and the mechanical properties are not sufficient.

Furthermore, Japanese Patent Application Laid-open No. 62-267323, 62-
285916, 63-099227 etc.

[Chemical 9] Although there is a description of a method containing components, this method also essentially contains U.
Only a polymer similar to the polymer of SP3, 804, 805 is obtained, and the heat resistance and mechanical properties are not sufficient. JP-A-52-121095 describes a method using diphenyl carbonate, but this method can only produce products with properties equivalent to those described above, and the heat resistance and mechanical properties are not sufficient.

Furthermore, in JP-A No. 63-317524, a method of improving elongation and anisotropy of physical properties is considered using a system using an aliphatic diol other than ethylene glycol. No method has been proposed for further improving the above effects (particularly improvement in elongation) by using only ethylene glycol as the group glycol. Therefore, the present inventors

A liquid crystalline polyester consisting of the structural unit of [Chemical formula 10], which has high tensile strength, bending strength, impact strength, etc., high elongation at break, and excellent heat resistance.Although it has excellent heat resistance in solid form, it starts to flow. Then, by raising it to a slightly higher temperature, it has very good fluidity (in order to do this, it is in a solid state and exhibits heat resistance up to a certain temperature T1, and it shows very good fluidity at a temperature of T2. , T1 is as high as possible, T2 −T
1 should be made as small as possible. ), and therefore it has excellent moldability, and even if it is a copolymer, it shows as high crystallinity as possible in the solid state to improve mechanical properties, improve hydrolysis resistance, and fillers, etc. We believe that there are systems in which it is possible to significantly improve mechanical and thermal properties when mixed, and this is possible by controlling the sequence and composition distribution, and specifically by increasing the alternating We thought that it would be a good idea to create a unique sequence, and we thought about it carefully. As a result, we discovered a method for producing liquid crystalline polyester having the above characteristics. (Japanese Patent Application No. 2-91640) However, the above-mentioned Patent Application No. 2-91640
The production method of No. 1 causes problems such as sublimation and side reactions during production. Furthermore, since a strong esterification catalyst or a strong transesterification catalyst is used during the synthesis of the compound of formula (6-1), a trace amount of the catalyst remains in the compound of formula (6-1), resulting in a liquid crystalline product. It tends to have a negative effect on the physical properties of polyester.

[0016]

[Means for Solving the Problems] The present inventors have intensively studied the method for producing copolyester of Japanese Patent Application No. 2-91640 that does not cause the above-mentioned problems.

It was discovered that this can be achieved by using the compound represented by the following formula, and the present invention was achieved. That is, the present invention was achieved by discovering a method for producing liquid crystalline polyester that does not have the problem of sublimation and in which trace amounts of strong esterification catalysts derived from raw materials and strong transesterification catalysts are not present in the produced polyester.

The present invention will be explained in detail below. The liquid crystalline polyester of the present invention is characterized by high strength and high elongation at break, making it a tough polymer.Furthermore, it has excellent solid heat resistance within the same composition and composition ratio.
Furthermore, since the T2 - T1 mentioned above is extremely small, it has the characteristic that it can be molded at a low temperature, and furthermore, it has the characteristic that mechanical properties are generally better when molded at a lower temperature, that is, a temperature slightly higher than the melting point. have

Furthermore, since these liquid crystalline polyesters exhibit high liquid crystallinity in the solid state, their hydrolysis resistance is improved,
It has the characteristic that mechanical properties and thermal properties can be improved when a filler or the like is mixed therein. The reason why we were able to develop such a liquid crystalline polyester is that we arrived at the present invention based on the ideas shown below.

That is, the following structural units (1) and (2) are mainly used.
), (4)

It was thought that this could be achieved by reducing [Image Omitted] as much as possible.

[0020] JP-A-60-186527 and JP-A-64 which are improvements on the conventional crystalline polyester of Jackson et al.
-26632 and JP-A-2-45524 improve heat resistance and mechanical properties, but these are just

[
[Image Omitted] The components were present in blocks in the polymer, but were merely made random, and the randomness was qualitative, and the measure of the randomness was not quantified.

The present inventors have discovered that it is not possible to satisfy all of the above-mentioned physical properties if the above-mentioned components are present randomly in the polymer, but that this can be achieved by making them exist alternately. . (Japanese Patent Application No. 2-91640) The present invention is an improved method for producing liquid crystalline polyester having a more alternately controlled sequence as described in Japanese Patent Application No. 2-91640. That is, the liquid crystalline polyester obtained by the production method of the present invention has the following formula (
Dicarboxylic acid unit represented by 1)

Diol unit -OCH2 CH2 O- represented by the following formula (2) (wherein R1 is as described above)
...(2) Benzoic acid unit represented by the following formula (4)

A liquid crystalline polyester consisting of [Chemical formula 15], in which each mole number is

[Formula 2] The oxybenzoic acid unit in which a diol unit is present on the carbonyl group side of the oxybenzoic acid unit is (4-4)

[Chemical formula 16] Then, r3 defined by the following formula is

The range is [Equation 3]. The characteristics of the liquid crystalline polyester produced by the production method of the present invention are as follows: 1. It has high tensile strength and bending strength. 2. Has high impact strength. 3. Has high elongation at break. 4. Heat resistance is high with the same composition and composition ratio. 5. Since T2 - T1 is small, the molding temperature can be lowered. 6. Molded products at lower temperatures have better mechanical properties. 7. The apparent activation energy of melt viscosity is small. 8. Highly crystalline. 9. Good hydrolysis resistance. 10. The effect of mixing fillers and the like becomes noticeable. etc. The physical properties of the polymer produced by the production method of the present invention are much better in balance between mechanical properties and thermal properties than those of conventional polymers, but individual physical properties may be inferior in some cases.

Furthermore, the fact that the molding temperature can be lowered despite its high heat resistance means that the polymerization temperature during production can be lowered, making it possible to produce polymers with good heat resistance using conventional production equipment. It means that. R1 of the dicarboxylic acid unit represented by formula (1) has 6 to 6 carbon atoms.
18 divalent aromatic hydrocarbon groups, specifically

[Image Omitted] and the like. These may be used alone or may be mixed to form a copolymer. Of these

Preferably, one is selected from one of the following, and the total molar ratio of R1 is preferably 50% or more, more preferably 66% or more.

[0023] A preferable mixture system is

[Image Omitted] [Image Omitted] Of course, three or more types of these may be used, but up to two types are preferable.

The manufacturing method of the present invention will be explained below. First, as a raw material

Acetylation etc. are carried out at 100 to 170°C by adding acetic anhydride to [Chemical Formula 20]. This ranges from 5 minutes to 3 hours, preferably from 20 minutes to 1.5 hours.
It's time. The amount of acetic anhydride is

[Math 4]

Before acetyl (8), (9), (10),
(11) may be reacted in advance, or (11) may be reacted in advance.
11), (9), and (10) may be reacted in advance. In that case

[Math 5] It is preferable to carry out within the range of

[Math 6] is preferred.

[0026] This reaction may be carried out using a solvent, but
Considering subsequent removal, etc., it is preferable to carry out the reaction without a solvent. When (11) is reacted with (9) and/or (8), it is preferable to add (9) and/or (8) to a place where (11) is melted. However, if the temperature gets too high, (11) and (9)

[C21] This is not desirable because it creates a structure.

[0027] Therefore, the temperature is 145°C to 220°C.
Preferably, it is carried out at °C. In particular, 170°C to 210°C is more preferable. In the case of (11), (10) and/or (8)

[Image Omitted] Since the structure is difficult to form, it may be possible to raise the temperature a little, but if the temperature is too high, the structure (13) will be formed at the initial stage of the reaction, which is not preferable.

[0028] Specifically, it is preferable to conduct the reaction at a temperature of 145°C to 230°C. The ratio of (11) and (8) is determined from the viewpoint of the degree of polymerization.

[Math 7]

In the case of [Equation 8], the heat resistance is lowered and the liquid crystallinity is also lowered, resulting in poor fluidity, which is not preferable.

All or part of (8) and all or part of (10) may be added during or after acetylation. After the acetylation is completed, the temperature is raised and polymerization begins. Polymerization is carried out at 220 to 340°C, especially at 26°C.
Preferably, the temperature is 0 to 320°C. Especially 265-30
Preferably it is carried out at 0°C. In particular, the temperature is preferably 265 to 290°C, most preferably 265 to 280°C. 260
If it is less than 320°C, the polymerization rate will be very slow, and if it exceeds 320°C, the physical properties of the resulting polymer will deteriorate, which is not preferable. It is preferable that the polymerization temperature is lower because transesterification reaction is less likely to occur.

The production method of the present invention has the advantage that it can be polymerized at a low temperature in spite of the heat resistance of solids. Also, 760
The time required to gradually reduce the pressure from mmHg to 1 mmHg is 30 minutes or more, preferably 60 minutes or more, and it is particularly important to gradually reduce the pressure from 30 mmHg to 1 mmHg. Although it is possible to carry out the polymerization without a catalyst, it is carried out in the presence of a catalyst if necessary. The catalysts used include transesterification catalysts, polycondensation catalysts, acylation catalysts, and decarboxylic acid catalysts, and these may be used in combination. A preferred catalyst is S
n(OAc)2, Sb2O3, Fe(acac)
3, Co(OAc)2, NaOAc, KOAc, and the like. The amount used is 5 to 50% of the polymer.
000 ppm, preferably 10 to 5,000 ppm. More preferably, it is 20 to 500 ppm.

Manufacturing method of the present invention and JP-A-63-3175
Regarding the difference from the method described in No. 24, JP-A No. 6
As mentioned above, the inventors of No. 3-317524 did not believe that the physical properties of aliphatic glycols could be improved by using ethylene glycol alone, and they said that they improved the aliphatic glycol because transesterification and acidolysis reactions are difficult to proceed with C3 and above. Ru. In addition, they are based on the inventors' earlier application (Japanese Patent Laid-Open No. 60-18
6525) and believes that acidolysis can be carried out sufficiently if ethylene glycol is used in this method.
From the beginning, we did not consider improving the physical properties by using only ethylene glycol.

As mentioned above, the present inventors found that even in the case of ethylene glycol, transesterification and acidolysis are not sufficient, and therefore, there are problems in production.

The inventors of JP-A No. 63-317524 believed that transesterification and acidolysis would be sufficiently carried out in the case of ethylene glycol. This is very different from what you are used to.

Furthermore, the liquid crystalline polyester produced by the production method of the present invention exhibits optical anisotropy in the molten phase. In particular, once melting begins, by simply raising the temperature a little above the melting start temperature, almost all of the solid portion disappears, and almost all of it can take a liquid crystal state, so it has a characteristic that its fluidity is much better than conventional polyester in terms of ηinh. Therefore, it has good moldability and can be subjected to general melt molding such as extrusion molding, injection molding, and compression molding, and can be processed into molded products, films, fibers, etc.

[0034] It is particularly suitable for precision molded products because of its high fluidity. For example, automobile parts, information material parts such as compact disks and floppy disks, connectors,
It can be used for electronic material parts such as IC sockets. Furthermore, during molding, fibers such as glass fibers and carbon fibers, talc,
Fillers such as mica and calcium carbonate, nucleating agents, pigments,
It is also possible to add desired properties to the molded article by adding fillers and additives such as antioxidants, lubricants, other stabilizers, flame retardants, thermoplastic resins, and the like. It is also possible to create a composition that combines the characteristics of other polymers and the advantages of the copolyester of the present invention by blending or alloying with other polymers.

[0035]

[Example] Next, the present invention will be explained in more detail.
The present invention is not limited to the following examples unless it exceeds the gist thereof. In addition, a Shimadzu flow tester was used to measure the melt viscosity in the examples, and a shear rate of 1000 s was used.
ec -1, cylinder nozzle length/diameter = 20 was used. Optical anisotropy (liquid crystallinity) was observed using a polarizing microscope with a hot stage.

[0036] Molding was performed using a 0.1 oz injection molding machine manufactured by Nippon Steel Corporation to produce a molded piece. The tensile properties (tensile modulus, tensile strength, elongation at break) of the above 0.1 oz molded product were TENSILON/UT manufactured by Toyo Baldwin Co., Ltd.
Measured using M-III L. Regarding the tensile elongation at break, a 0.1 oz molded piece (dumbbell piece) has lower elongation and considerably lower strength than an ASTM molded piece. Therefore, if this molded piece has an elongation of 3.2% or more, it can be said that the polymer is quite tough. Moreover, if it is less than 3.0%, it can be said that the polymer is quite brittle.

Reference example

embedded image 138 parts by weight of p-hydroxybenzoic acid, Na2 CO3
1 part by weight and 300 parts by weight of isopropanol were placed in an autoclave, and 66 parts by weight of ethylene oxide was added at 90°C to carry out a reaction. After the reaction, cool, filter the precipitate, and recrystallize twice from water to obtain a product with a melting point of 141°C.

[C25
] was obtained in an amount of 55 parts by weight. The structure was confirmed by 1H-NMR.

Example 1 Glass polymerization tube equipped with stirring blades, nitrogen inlet, and pressure reduction port

[
[Chemical Formula 26]] was charged, and the mixture was replaced with N2 under reduced pressure.The system was then turned into a N2 flow and the temperature was raised while stirring the system. Becomes transparent at 170℃ and becomes 180℃
When the temperature reached 200°C, the temperature was held for 2 hours, and then the temperature was raised to 200°C and held for 1 hour. As the reaction proceeded, the system became opaque and finally solidified. next,

[Chemical Formula 27] was added, and acylation was carried out for 1 hour while maintaining the temperature at 140°C with stirring. Thereafter, the temperature was increased to 275° C. over 1.5 hours, and pressure reduction was started. The pressure was reduced to 10 mmHg in the first hour, and then from 10 mmHg to 0.3 mmH over the next 1.5 hours.
I made it g. After 1 hour of polymerization at 0.3 mmHg, the torque was sufficiently increased and the polymerization was terminated. Almost no sublimation was observed. Thereafter, the tube was allowed to stand, and the pressure was restored to extract the polymer from the bottom of the tube. The extractability was very good. After being made into chips, it was dried at 120°C overnight. This polymer had an ηinh of 1.00 dl/g and a melt viscosity of 730 poise at 275°C. Next, a dumbbell piece was molded using a 0.1 oz injection molding machine and its mechanical properties were measured; the elongation at break was 3.3%, the strength was 2,000 kg/cm2,
The elastic modulus was 9.0 x 104 kg/cm2.

Example 2 Glass polymerization tube equipped with stirring blades, nitrogen inlet, and pressure reduction port

[
After charging the mixture with N2 and reducing the pressure, the system was turned into a N2 flow and the temperature was raised while stirring the system. It became transparent at 200°C and was kept for 2 hours to react. next,

embedded image was added, and when the temperature reached 140° C., the temperature was maintained for 1 hour while stirring. Thereafter, the temperature was increased to 275° C. over 1.5 hours, and pressure reduction was started. The pressure was reduced to 10 mmHg in the first hour, and then from 10 mmHg to 0.3 mm over the next 1.5 hours.
I changed it to Hg. After 3 hours of polymerization at 0.3 mmHg, the torque was sufficiently increased and the polymerization was terminated. Almost no sublimation was observed. Thereafter, the tube was allowed to stand, and the pressure was restored to extract the polymer from the bottom of the tube. The extractability was very good. After being made into chips, it was dried at 120°C overnight. This polymer had an ηinh of 1.03 dl/g and a melt viscosity of 700 poise at 275°C. Next, a dumbbell piece was molded using a 0.1 oz injection molding machine and its mechanical properties were measured, and the elongation at break was 3.4% and the strength was 2,020 kg/cm2.
, the elastic modulus was 9.5 x 104 kg/cm2.

Example 3 Glass polymerization tube equipped with stirring blades, nitrogen inlet, and pressure reduction port

[
After charging and purging with N2 under reduced pressure, the system was heated to 200° C. with stirring, and the system was heated to 200° C. and reacted for 2 hours. Next, 20.5 g (0.201 mol) of acetic anhydride was added, and the same procedure as in Example 1 was carried out. However, the total polymerization time was 3 hours. Almost no sublimation was observed. The extractability of the polymer was good, with ηinh =1.13. The strength of this polymer is 2040 kg/cm2,
Elastic modulus 9.5×104 kg/cm2, elongation at break 3
．． It was 6%.

[0041]

[Effect of the invention] The production method of the present invention uses

[C31
] Since it is inexpensive, manufacturing costs can be reduced. In addition, since a strong esterification catalyst or a strong transesterification catalyst is not used in the raw materials, there are few side reactions such as transesterification, making it very useful industrially.

Claims (4)

[Claims] [Claim 1] A dicarboxylic acid unit represented by the following formula (1), [Formula 1] (In the formula (1), R1 represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.) The following formula: Diol unit represented by (2), -OCH2 CH2 O-...
(2) Oxybenzoic acid unit represented by the following formula (4) [
A liquid crystalline polyester characterized by reacting a compound represented by the following formula (11) with acetic anhydride and polycondensing it in a molten state as a starting material for producing a copolymerized polyester consisting of the following formula (11): Production method. [Claim 2] The compound of formula (9) is [Formula 4], and (9-1), (9-2), (10-1), (1
The number of moles of 0-2) is [9-1], [9-2], [10-
1] and [10-2], the following formula is satisfied: 1) The method for producing a liquid crystalline polyester according to claim 1, wherein the following formula is satisfied. 3. The method for producing a liquid crystalline polyester according to claim 1, wherein the melt polymerization is carried out at 280° C. or lower. 4. A compound of formula (11) and part or all of formula (9) and/or formula (10) and/or formula (
The reaction temperature for charging and reacting the compound in 8) was 230°C.
2. The method for producing a liquid crystalline polyester according to claim 1, which is carried out in the following steps.