JPH0139450B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing aromatic polyester. Fully aromatic polyester has excellent properties based on its structure, but it stands out among all resins in terms of heat resistance. Among these, wholly aromatic polyesters produced from terephthalic acid, isophthalic acid, parahydroxybenzoic acid or its derivatives, and 4,4'-dihydroxyphenyl or its derivatives can be injection molded and have various physical properties, such as mechanical properties and electrical properties. In addition to having excellent physical properties and thermal stability, it also has high heat resistance, chemical resistance, oil resistance,
It has many excellent properties such as radiation resistance and dimensional stability, and is suitable for mechanical parts, electrical/electronic parts,
It is used in various fields such as automobile parts. However, such wholly aromatic polyesters have the drawbacks of high melt viscosity and poor moldability due to their high softening temperatures. Furthermore, since high molding temperatures are required, there are problems such as thermal deterioration and coloring of the polymer during molding, and from these points of view as well, improvements in moldability have been desired. A conventionally known method for solving this problem is to blend it with a resin that has better fluidity (good moldability). For example, it is blended with polyethylene phthalate polycarbonate and molded. However, when mixing, granulating, and molding the fully aromatic polyester obtained from terephthalic acid, isophthalic acid, parahydroxybenzoic acid, 4,4'-dihydroxydiphenyl, etc., and polyethylene phthalate or polycarbonate, If each process is carried out in the temperature range where aromatic polyester is homogenized, polyethylene phthalate and polycarbonate, which have poor thermal stability at this temperature, tend to thermally decompose, and these resins are processed in a temperature range where they can be stabilized and homogenized. In this case, the entire composition system does not become a uniform dispersion because the temperature is insufficient for the flow of the wholly aromatic polyester. Although it is possible to lengthen the residence time of the resin in each process such as mixing, granulation, and molding in order to homogenize the entire system, it is far from uniformly dispersed, and it takes a lot of time to achieve that state. That's not realistic. Alternatively, in order to lower the molding temperature of wholly aromatic polyester, a wholly aromatic polyester with a low molecular weight is mixed, granulated, and molded with a resin having excellent moldability, as described above. Although it is possible to do so, the various excellent properties of wholly aromatic polyesters will be degraded. A blending method using a solution is also considered, but
In the case of wholly aromatic polyester, a solvent that can uniformly dissolve it without decomposition has not yet been found, and it can be said that it is extremely difficult. If the dispersibility is insufficient, parts of the resin or molded product may deteriorate when exposed to solvents or reagents, variations may occur from shot to shot during molding, or the strength of the molded product may be non-uniform. As mentioned above, from the normal blending method,
It can be said that it is difficult to improve the moldability of the above-mentioned wholly aromatic polyester. In view of the current situation, the present inventors have conducted extensive studies to improve the moldability of wholly aromatic polyester without the deterioration of physical properties or inconveniences caused by poor dispersion that occur in conventional blending methods. As a result, during the production of fully aromatic polyester, aromatic polysulfone is present in a certain proportion in the polymerization reaction system, and the polymerization is carried out using a bulk polymerization method in which substantially no solvent is present. It has been found that the moldability of wholly aromatic polyester can be improved without reducing its excellent performance. The aromatic polysulfone must be present during the polymerization of the fully aromatic polyester. It has been difficult to improve moldability by simply blending aromatic polysulfone with wholly aromatic polyester. This is thought to be due to poor uniform dispersibility. In the case of blends, non-uniform patterns were observed on the surface of the molded product. Further, the polymerization must be carried out by a bulk polymerization method in which substantially no solvent is present. Methods for producing aromatic polyester include solution polymerization, in which the produced polymer is dissolved in an organic solvent as the polymerization solvent, suspension polymerization, in which the produced polymer is precipitated from the solvent used for polymerization, and bulk polymerization, in which no solvent is used. Polymerization methods are known. In the case of fully aromatic polyesters produced from terephthalic acid, isophthalic acid, parahydroxybenzoic acid, and 4,4'-dihydroxydiphenyl, no solvent has been found to date that can dissolve them, so the solution polymerization method is used. is difficult to employ. High-boiling point solvents such as hydrogenated terphenyl, diphenyl ether, and diphenyl mixtures are used in the suspension polymerization method, but the process is complicated, including removal and recovery of these solvents, and washing of the polymer. It has the economic disadvantage of low polymer production. Bulk polymerization is the most economically advantageous polymerization method, but it has not been widely applied to the production of aromatic polyesters. The reason for this is that aromatic polyesters have a higher melting point than aliphatic polyesters such as polyethylene terephthalate, and require high temperatures to maintain their molten state, which can significantly reduce the value of the polymer as a product. This is because it will be done. If this problem of color deterioration can be solved, it will have great industrial significance as a process that can satisfy both polymer quality and economic efficiency. The present inventors have found that when producing the above fully aromatic polyester, aromatic polysulfone is present in the polymerization reaction system and polymerization is carried out by a bulk polymerization method in which substantially no solvent is present. In addition to fully aromatic polyester obtained by polymerization without the presence of aromatic polysulfone, or even if aromatic polysulfone is present, other methods (e.g. suspension polymerization) can be used.
The present inventors have discovered that the polyester has better moldability and superior physical properties than the aromatic polyester obtained in the above-mentioned aromatic polyester. That is, the present invention provides the following repeating units [],
When producing a wholly aromatic polyester composed of [] and [] (hereinafter referred to as a wholly aromatic polyester represented by the general formula A), an aromatic polysulfone represented by the repeating unit [] is finally produced in the polymerization reaction system. The present invention relates to a method for producing an aromatic polyester, characterized in that the aromatic polyester is present in a proportion of 5 to 40% by weight of the polymer, and the polymerization is carried out by a fracture polymerization method substantially in the absence of a solvent. (In the above formula, X is a C ₁ to C ₄ alkyl group, -O-, -
SO ₂ -, -S- or -CO-, m and n are 0
or 1. []: [] ratio is from 1:1
It is in the range of 10:1, and the ratio of []:[] is 9:10
and 10:9. Furthermore, the substituents on the aromatic ring in the above formula are in para or meta positions with respect to each other. ) (In the above formula, Y is -O-, -S-,

[expression] or

One or more are selected from [expression]. ) The aromatic polyester obtained in the presence of aromatic polysulfone has improved moldability compared to polymerization in the absence of aromatic polysulfone, and has improved moldability compared to a simple blend of aromatic polysulfone. The surface and interior of the molded product are uniform and well dispersed. Furthermore, results were obtained in which there was less deterioration in various physical properties, especially in thermal stability and mechanical strength, as seen in blended products. In addition, by polymerizing in the presence of aromatic polysulfone, an aromatic polyester with little color deterioration can be obtained even when bulk polymerization is used, and the moldability is improved, resulting in an aromatic polyester that is satisfactory in both economical efficiency and polymer quality. A method for producing family polyesters has been discovered. The reduction in color deterioration during bulk polymerization is thought to be due to the reduction in melt viscosity due to the aromatic polysulfone. Examples of the components of the wholly aromatic polyester used in the present invention include parahydroxybenzoic acid, metahydroxybenzoic acid, terephthalic acid, isophthalic acid, hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, and 4,4'-dihydroxydiphenyl. enyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylmethane, etc. and their derivatives. Can be used. Among these combinations, combinations of parahydroxybenzoic acid or its ester, terephthalic acid or its ester, and 4,4'-dihydroxydiphenyl or its ester are particularly preferred. The aromatic polysulfone used in the polymerization of the fully aromatic polyester of the present invention has the general formula

[Formula] (In the above formula, Y is -O-, -S-,

[expression] or

One or more are selected from [expression]. ) It has a structural unit represented by . As an example

"Victrex" by Imperial Chemical Industries, which has a repeating unit of [formula] Examples include UCC's "Udel," which has a repeating unit of The amount of aromatic polysulfone used during the polymerization of fully aromatic polyester is 5 to 50% of the final product polymer.
Must be 40% by weight. Below this range, the effect will not be sufficient, and above this range, the resulting aromatic polyester will not have sufficient thermal and mechanical properties. As the polymerization method, a bulk polymerization method is used.
Any generally known bulk polymerization method may be used. One example is a method in which a compound for forming a wholly aromatic polyester represented by the general formula A and an aromatic polysulfone are simultaneously charged into a reaction tank. The polymerization reaction is then heated to carry out the polymerization reaction at approximately 200 to 400°C.
Preferably, the reaction is carried out at 250 to 350° C. under normal pressure or reduced pressure in an inert gas atmosphere. It is also possible to proceed with the polymerization using a catalyst whose residue does not adversely affect the physical properties of the polymer or whose activity can be rendered inactive by simple treatment. A more preferable bulk polymerization method is to proceed with the polymerization by constantly applying a shearing force to the polymer produced by polymerization at the polymerization temperature so as not to solidify the polymer, and to form a solid polydisperse system without solidifying the polymer. This is a method in which polymerization is carried out until substantially all of the solid phase is obtained in the same state, and the maximum temperature that can be used depends on the monomers used,
This temperature limit, which depends in part on the boiling point and decomposition point of the oligomer or polymer, is such that the condensation is initially carried out at a relatively low temperature and the temperature is increased as the condensation progresses. Polymerization is carried out initially at a temperature of 180-250°C, then at an increased temperature of 250-380°C, preferably at 300-360°C, under normal pressure or reduced pressure. Once it becomes a solid polydispersion, it is possible to raise the temperature while taking into account its fusion temperature and decomposition temperature, and it is possible to raise the temperature to 300 to 400 °C, preferably 310 to 370 °C, but even if it is below the decomposition temperature and below the fusion temperature. For example, the higher the value, the faster the reaction rate. Alternatively, a compound for forming a wholly aromatic polyester represented by the general formula A and an aromatic polysulfone are simultaneously charged into a first reaction tank, a prepolymer is produced by polycondensation, and a prepolymer is produced by polycondensation.
A method of transferring to a reaction tank and increasing the molecular weight is also used. The prepolymer produced in the first reaction tank may be taken out in a molten state, pulverized and homogenized, and then made to have a high molecular weight in the second reaction tank. The molecular weight may be increased in a reaction tank. Alternatively, as yet another method, there is a method in which the aromatic polysulfone is not added from the beginning, but is added sequentially during the polymerization reaction of the wholly aromatic polyester represented by the general formula A. If this method is carried out in two-stage polymerization using a first and second reaction tank, it is more preferable to add it sequentially during polymerization in the first reaction tank. The aromatic polyester thus obtained is a polymer with little coloration, excellent moldability, and excellent heat resistance and mechanical properties. The aromatic polyester obtained according to the present invention can contain additives commonly used in plastics, such as stabilizers, colorants, fillers, etc., to the extent that they do not impair the properties of the polymer. Fillers include, for example, silica, powdered quartz or sand, fumed silica, silicon carbide, aluminum oxide, glass fibers, tin oxide, iron oxide, zinc oxide, carbon, graphite, and as pigments titanium dioxide and other inorganic materials and heat-resistant materials. Organic pigments can be used. The polymer obtained by the present invention can be press-molded,
Using methods such as injection molding and extrusion molding, molded products, films, and sheets are used in a wide range of fields that require high performance as engineering plastics, such as mechanical parts, electrical and electronic parts, automobile parts, various containers, and packaging materials. used. The present invention will be explained below with reference to Examples and Comparative Examples, but these are illustrative and not limiting. Example 1 756 g (5.48 mol) of parahydroxybenzoic acid and terephthalic acid were placed in a polymerization tank that had an anchor-type stirring blade and had a small clearance between the tank wall and the stirring blade.
453 g (2.73 moles), 508 g (2.73 moles) of 4,4'-dihydroxydiphenyl, 169 g of polyether sulfone (Victrex 100P manufactured by Imperial Chemical Industries) (of the final polymer
10% by weight) and 1337 g of acetic anhydride (13.1
mole) was added. The repeating unit of Victrex 100P is

[Formula], and the reduced viscosity of a 1% W/V dimethylformamide solution at 25°C is 0.53 dl/g. 150 in 1 hour while stirring under nitrogen gas atmosphere
The mixture was heated to 0.degree. C. and refluxed at that temperature for 3 hours. Thereafter, the acetic acid produced as a result of the reaction was distilled off while raising the temperature, and the temperature was raised to 330°C under high shear. Polymerization was further continued for 2 hours with strong stirring, then gradually cooled down to 200°C, and strong stirring was continued, after which the polymerized product was taken out of the tank. The recovered amount was 1570g (theoretical amount)
93.1%). After pulverizing this, it was transferred to an aluminum rotary oven, and the entire system was rotated under a nitrogen stream to thoroughly stir the powder and heated to 320℃.
The temperature was gradually increased over a period of time and the mixture was treated at 320°C for 3 hours, then cooled and the powder was taken out at 200°C. The powder obtained weighed 1540 g. This polymer was granulated using a single-screw extruder VS-30-28 (screw diameter 30 mm, L/D ~ 28) manufactured by Tanabe Plastic Machinery at a cylinder temperature of 320°C and screw rotation speed of 50 rpm, and then injection molded by Sumitomo Heavy Industries. Injection molding was performed using a molding machine Neomats N47/28. Barflow flow length was measured using various molds, and dumbbell-shaped test pieces and Izot impact strength test pieces were molded, and the physical properties of each were measured. The results are shown in Table 1. Comparative Examples 1 to 3 described below
It can be seen that the molding temperature range is wider and molding can be performed at a relatively low temperature compared to the above. In addition, the appearance of the molded product is smooth, and the dependence of physical properties on molding temperature is small. Comparative Example 1 Polymerization and post-treatment were carried out in the same manner as in Example 1 except that the polyether sulfone was not used at all.
1412 g (93.0% of theory) was obtained. This product was granulated and injection molded in the same manner as in Example 1. Table 1 shows the results.
Shown below. Compared to Example 1, the molding temperature range is narrower and a higher temperature is required. Orientation was observed in the molded product, and the physical property values were generally high or the molding temperature dependence was greater than in Example 1. Comparative Example 2 Fully aromatic polyester 900 obtained in Comparative Example 1
g is polyether sulfone 100 used in Example 1.
g were mixed and stirred using a super mixer. The obtained polymer was granulated and injection molded in the same manner as in Example 1. The results are shown in Table 1. Although the molding temperature range is slightly wider than that of Comparative Example 1, it is narrower than that of Example 1, and the molded product is non-uniform, with some burns observed during high-temperature molding. In addition, the physical property values are generally low. Comparative Example 3 900 g (5.0 mol) of paraacetoxybenzoic acid, 415 g (2.5 mol) of terephthalic acid, 675 g (2.5 mol) of 4,4'-dihydroxydiphenyl diacetylated product, polyether sulfone (Victrex 100P manufactured by Imperial Chemical Industries)
154g (equivalent to 10% by weight of the final polymer)
and 1400 g of Santotherm 66 (manufactured by Mitsubishi Monsanto Chemical Co., Ltd.) as a high boiling point solvent were placed in a reactor, and the mixture was heated to 180°C in 1 hour with constant stirring in a nitrogen gas atmosphere, and then heated for another 10 hours. The temperature was raised to 320℃. Continue stirring at 320℃
A slurry was formed by heating for 16 hours followed by 3 hours at 340°C. The reaction mixture was allowed to cool, and 1000g of Santotherm 66 was added, and the mixture was heated to 7°C.
And so. 1920 g of acetone was added, the slurry was filtered, and the powder was Soxhlet extracted with acetone to remove Santotherm 66. This powder was dried under reduced pressure at 110℃ for 5 hours to give 1340g of polymer (theoretical amount of 86.8g).
%) was obtained. This powder was transferred to an aluminum rotary oven and kept at 200℃ for 10 hours while rotating the entire system under nitrogen flow and thoroughly stirring the powder, then heated to 300℃.
The temperature was gradually increased until 6 hours, and at this temperature 2
After keeping it for a while, it was cooled to 200°C and the powder was taken out. This polymer was granulated and injection molded in the same manner as in Example 1. The results are shown in Table 1. The molding temperature range is almost the same as Comparative Example 2 and narrower than Example 1. Also, the molded product is uneven and burns can be seen when molded at high temperatures. Moreover, the physical property values are also lower than those of Example 1.

[Table] Example 2 In the same manner as in Example 1, the polyether sulfone used in Example 1 was added to 10% of the final polymer,
Polymers were obtained by polymerization in proportions of 20%, 30%, and 40%. These were granulated in the same manner as in Example 1 to obtain pellets. Dumbbell-shaped test pieces, Izot impact strength test pieces, weld strength test pieces, and heat distortion temperature measurement test pieces were injection molded using various molds, and the physical properties of each were measured. The results are shown in Table 2. For comparison, a case where polyether sulfone was 0.50% is also shown.

【table】

[Table] It can be seen that polyether sulfone improves the appearance of the molded product and also significantly improves various physical properties, especially the strength of the weld part. Furthermore, the dependence of physical properties on molding temperature is also becoming smaller. 50wt polyether sulfone is the final polymer
%, the appearance is good, but the physical property values are generally low. Example 3 Into the same apparatus as in Example 1, 1122 g (8.13 mol) of parahydroxybenzoic acid and 450 g (2.71 mol) of terephthalic acid were added.
mole), 4,4'-dihydroxydiphenyl 504g
(2.71 mol) Polysulfone (UCC/P-
1700) 458.7 g (corresponding to 20% by weight of the final polymer produced) and 1659 g of acetic anhydride were charged. Furthermore, P
The repeating unit of −1700 is 0.2% W/V chloroform solution, 25°C
The reduced viscosity at is 0.48 dl/g. The subsequent operations were carried out in the same manner as in Example 1 to obtain 2112 g of polymer (92.1% of theory). Example 1
It was granulated and injection molded in the same manner as above, and the physical properties were measured.
The results are shown in Table 3.

[Table] Example 4 756 g (5.48 mol) of parahydroxybenzoic acid and 453 g (2.73 mol) of terephthalic acid were placed in the same apparatus as in Example 1.
mole), 4,4'-dihydroxydiphenyl 410g
(2.20 mol), hydroquinone 59.4g (0.54 mol),
(Victrex 200P manufactured by Imperial Chemical Industries) 369g (of the final polymer
This corresponds to 20% by weight. ) 1337 g (13.1 mol) of acetic anhydride was charged. The repeating unit of Victrex 200P is

[Formula], 1% W/V dimethylformamide solution,
The reduced viscosity at 25°C is 0.41 dl/g. Example 1
The subsequent operations were carried out in the same manner as above to obtain a polymer. Mix 400g of glass fiber with 600g of this polymer,
After being almost uniformly dispersed, it was granulated and injection molded.
The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. When producing a wholly aromatic polyester composed of the following repeating units [], [] and [], the aromatic polysulfone represented by the repeating units [] is added to the final product polymer in the polymerization reaction system. present in a proportion of 5 to 40% by weight,
A method for producing an aromatic polyester, characterized in that the polymerization is carried out by a bulk polymerization method in the absence of substantially any solvent. (In the above formula, X is a C ₁ to C ₄ alkyl group, -O-, -
SO ₂ -, -S- or -CO-, m and n are 0
or 1. []: [] ratio is from 1:1
It is in the range of 10:1, and the ratio of []:[] is 9:10
and 10:9. Furthermore, the substituents on the aromatic ring in the above formula are in para or meta positions with respect to each other. ) (In the above formula, Y is -O-, -S-,
One or more are selected from [Formula] or [Formula]. )