JPH0454692B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical field The present invention relates to fibers, films, and fibers with excellent physical properties.
The present invention relates to a method for producing high molecular weight polyester useful as a raw material for other molded products. More specifically, the present invention relates to a method for producing a high molecular weight polyester having an intrinsic viscosity of 1.0 or more by a melt polymerization method. (b) Prior Art It is well known that polyester, represented by polyethylene terephthalate, is used as a raw material for manufacturing fibers, films, and other molded products. Molecular weight is a major factor that affects the physical properties such as strength of these molded products, and increasing the molecular weight is desired in order to improve these physical properties. However, in the commonly performed deglycol-type polycondensation reaction, (1) since it is an equilibrium reaction, the molecular weight can only be raised to a molecular weight corresponding to the glycol partial pressure; and (2) in high-temperature polycondensation reactions, Because decomposition reactions also occur, it was thought to be difficult to obtain by the usual method of melt polymerization of high molecular weight polyesters. In order to solve these problems, a solid phase polymerization method in which a polymerization reaction is carried out at a low temperature is generally used. However, the solid phase polymerization method not only has problems such as the reaction taking a long time and the resulting polymer being difficult to dissolve, but also the intrinsic viscosity of the resulting polymer being approximately 1.4 at most. Conventionally, various studies have been made to obtain high molecular weight polyesters by improving the melt polymerization method, and a typical example thereof is the use of a chain extender. However, this method not only requires an expensive chain extender, but also the parts connected by the chain extender are thermally unstable, and compounds produced as by-products from the chain extender remain in the polymer. This has the disadvantage that it mixes into the by-produced ethylene glycol, making it difficult to recover the ethylene glycol. Further, even if this method is applied, it is difficult to obtain a high molecular weight polyester having an intrinsic viscosity of 1.8 or more. (c) Object of the Invention The object of the present invention is to provide a method for producing an unprecedented high molecular weight polyester using a melt polymerization method. (d) Solution The present inventor investigated the melt polymerization reaction of polyester in a high molecular weight region with an intrinsic viscosity of 0.8 or more, and found that the degree of polymerization of polyester reaches an equilibrium state with the reaction time at a temperature where the decomposition reaction can be ignored. As the speed approaches d(1/p)/dt=-k(1/p-1/p∞)...(1
) (where p indicates the degree of polymerization at reaction time t, and p∞ indicates the degree of polymerization in the equilibrium state),
It was found that 1/p∞ ² is proportional to the depth of the liquid.
This shows that the ultimate degree of polymerization changes depending on the hydraulic pressure, and we focused on the fact that if the effect of this hydraulic pressure can be reduced, the ultimate degree of polymerization can be increased. In other words, if we consider that in normal polyester polymerization, the liquid pressure is the same as the pressure of reaction byproducts such as glycol, the equilibrium reaction We focused on the fact that the square of the concentration of end groups (that is, the amount proportional to 1/p∞) is proportional to the depth of the liquid. If we consider this point further and make sure that the liquid pressure and the pressure of reaction by-products (glycol, etc.) are not equal,
That is, we have come to the conclusion that if the sum of the partial pressures of other gases and reaction by-products is made equal to the liquid pressure, the equilibrium in equation (2) will shift to the right and a high molecular weight polyester will be obtained. According to this way of thinking, we came to the conclusion that a high molecular weight polyester can be obtained if a substance that continuously generates gas during the reaction coexists. As a result of attempting to lower the partial pressure of reaction by-products by utilizing a reaction that produces a cyclic ester from polyester, it was confirmed that it was possible to obtain an unprecedented high molecular weight polyester, and the present invention was achieved. It is something. (e) Structure of the Invention The present invention is a method of melt polymerizing dicarboxylic acids, mainly aromatic dicarboxylic acids, and/or their ester-forming derivatives, and glycols, mainly ethylene glycol, and/or their ester-forming derivatives under reduced pressure. When producing polyester with an intrinsic viscosity of 1.0 or more by the method of
This is a method for producing a high molecular weight polyester, characterized by the presence of a compound (A) that generates a substance that is a gas and does not substantially reduce the molecular weight of the polyester under polymerization conditions at a stage of 0.8 or more. The polyester targeted in the present invention has an aromatic dicarboxylic acid as a main component and ethylene glycol as a main glycol component. Here, "mainly" means more than 50 mol%. Therefore, less than 50 mol% of other components may be contained. In the present invention, "aromatic dicarboxylic acid" refers to
These are compounds in which a carboxylic acid is directly bonded to an aromatic group, such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, and terephthalic acid is particularly preferred. In the present invention, the third component that can be copolymerized includes aromatic dicarboxylic acids other than the main constituent components of the polyester, aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, and decanedicarboxylic acid. ; Alicyclic dicarboxylic acids such as hexahydroterephthalic acid, decalindicarboxylic acid, and tetralindicarboxylic acid; glycolic acid, p
-Oxybenzoic acid; trimethylene glycol, propylene glycol, 1,4 butanediol,
Aliphatic diols other than the main constituent components of the polyester such as 1,3-butanediol, neopentyl glycol, and 1,6-hexanediol; alicyclic diols such as cyclohexane dimethylol and tricyclodecane dimethylol; bisphenol A, Aromatic diols such as bisphenol S, bishydroxyethoxybisphenol A, and tetrabromobisphenol A are exemplified. In addition, the ester-forming derivative refers to a derivative that can form an ester group when reacted with a dicarboxylic acid or glycol, such as lower alkyl esters of acids, aryl esters, and esters of diols. The aromatic dicarboxylic acid and/or its ester-forming derivative and ethylene glycol and/or its ester-forming derivative are melt-polymerized by adding the above-mentioned copolymerization components as necessary to produce a high molecular weight polyester having an intrinsic viscosity of 1.0 or more. In this invention, at least the intrinsic viscosity is
It is characterized in that the following compound (A) is present in the stage of 0.8 or higher. This compound (A) is
It is a compound that continuously generates a gaseous substance that does not substantially reduce the molecular weight of polyester under the polymerization conditions (temperature and pressure) when increasing the molecular weight of a polymer with an intrinsic viscosity of approximately 0.8. . Although it is preferable that this compound (A) is not a substance that lowers the molecular weight of the polyester, it is possible to use a compound that shows the effects of the present invention even if the molecular weight is temporarily lowered at the time of addition. The compound (A) having such properties may be copolymerized or mixed into the polyester. One specific example is a polyester obtained from an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and an aliphatic diol such as ethylene glycol. These aliphatic polyesters produce cyclic esters, which become gases under polymerization conditions and contribute to high molecular weight. This aliphatic polyester may be synthesized separately, or
It may be included in the target polyester as a copolymerization component. In this case, it is preferable to use a common glycol component in order to prevent a decrease in melting point. When using such a copolymerizable compound (A), one method is to add it from the beginning of the polymerization reaction. Specific aliphatic dicarboxylic acids include adipic acid, pimelic acid, superric acid, azelaic acid, sebacic acid, α,ω-nonanedicarboxylic acid,
Examples include α,ω-decanedicarboxylic acid and brassylic acid, and particularly preferred are suberic acid, azelaic acid, sebacic acid, α,ω-decanedicarboxylic acid and the like having 8 to 12 carbon atoms. A specific example is caprolactone, which has 5 carbon atoms.
-12 oxycarboxylic acids, polymers that gradually decompose at the polymerization temperature of the polyester of the present application, such as polystyrene polyoxymethyl, and the like. The oxycarboxylic acid may be added in the form of a polymer, or may be one of the copolymer components of the polyester of the present application. The amount of the compound (A) that continuously generates a gaseous substance that does not substantially reduce the molecular weight of the polyester under such polymerization conditions is 1 to 50% by weight, preferably 2 to 20% by weight. If it is added in too large a quantity, the effect will not be large and the desired physical properties of the polyester will be deteriorated, which is not preferable. Also, if the amount is too small, the effect will be low. The polymerization method of the present invention can be carried out in the same manner as a conventional polycondensation method. That is, so-called esters in which dicarboxylic acids and/or ester-forming derivatives thereof are reacted with aliphatic and/or alicyclic diols and/or ester-forming derivatives thereof in the presence or absence of a catalyst at normal pressure or under pressure. This is a method in which a polymerization reaction is carried out in which the degree of polymerization is increased under reduced pressure in the presence of a catalyst after carrying out a transesterification or transesterification reaction. In this polymerization method, the polymerization reaction is preferably carried out at as low a temperature as possible, preferably between 240 and 270°C. At too high a temperature, side reactions other than the exchange reaction of ester groups occur, resulting in a decrease in molecular weight. Further, it goes without saying that a higher degree of pressure reduction is preferable, and it is preferable that the degree of pressure reduction is 200 Pa or less, preferably 100 Pa or less. The reaction time varies depending on the catalyst, reaction apparatus, etc., but is generally 10 minutes to 20 hours. The catalyst used here can be any catalyst that is generally used for polyester polymerization, but
In particular, titanium compounds and tin compounds are preferably used. The titanium compound used in the present invention has the general formula

[Formula] , M[HTi(OR) ₆ ] ₂ (where R, R ₁ , R ₂ , R ₃ , R ₄ are alkyl groups,
aryl group, hydrogen and M represents an alkaline earth metal), such as tetrabutyl titanate, tetraisopropyl titanate,
Tetra(2-ethylhexyl) titanate, tetrastearyl titanate, diisoproboxybis(acetylacetonato)titanium, di-n-butoxybis(triethanolaminate)titanium,
Dihydroxybis(lactate) titanium, titanium isopropoxyoctylene glycolate, isopropoxytitanium triisostearate, titanate tetrabenzoate; magnesium titanium methylate, magnesium titanium butyrate, magnesium titanium octylate, calcium titanium butyrate, titanium ethyl In addition to strontium chloride, etc., these hydrolysates (including partial hydrolysates), transesterified products, those in which hydrolysis and transesterification are performed simultaneously, and the general formula Ti ₂ (C ₂ O ₄ ) ₂ , (M)nTi(C ₂ O ₄ ) ₂ , (M)n(C ₂ O ₄ ) ₂ , (
M)
nOTi(C ₂ O ₄ ) ₂ (here M represents a metal atom, H, NH ₄ , n is 1 when M is a divalent metal, M is H,
For NH ₄ and monovalent metals, compounds represented by 2), such as titanium oxalate, potassium dioxalate titanate (), ammonium dioxalate titanate (), hydrogen oxodioxalate titanate (), Examples include, but are not limited to, sodium dioxalate titanate (), barium oxodioxalate titanate (), calcium trioxalate (), and their hydrates. Among these, tetrabutyl titanate and tetraisopropyl titanate are particularly preferred. The tin compound used in the present invention has the general formula

[expression] or

[Formula] (R is an alkyl group, an aryl group, _{X 1 to} ), specifically, methylphenyltin oxide, tetraethyltin, dibutyltin oxide, didodecyltin oxide, triethyltin hydroxide, triphenyltin hydroxide, triisobutyltin acetate, dibutyltin diacetate, diphenyltin oxide, Examples include enyltin dilaurylate, monobutyltin trichloride, dibutyltin dichloride, tributyltin chloride, dibutyltin sulfite, and butyl hydroxytin oxide. Among these, dibutyltin oxide and butylhydroxytin oxide are particularly preferred. The apparatus for carrying out the present invention is preferably an apparatus that can handle highly viscous materials. For example, a kneader-like shape in which the space can be reduced in pressure, or an extruder-like shape (particularly a twin-screw type) in which the space can be reduced in pressure are preferably used. However, even if it is a simple stirring tank or a stationary type, it can be used satisfactorily as long as uniformity is not an issue and the method of taking out the liquid is devised. As mentioned above, since the depth of the liquid affects the distance, it is desirable that the distance from the external space to the center of the polymer mass be as small as possible, for example, 20 cm or less, preferably 10 cm or less. It goes without saying that pigments, dyes, stabilizers, crystallizing agents, lubricants, mold release agents, plasticizers, and other modifiers may be included in the present invention. (f) Examples The present invention will be explained in detail with reference to Examples below. Example 1 87.4 g of dimethyl terephthalate, 11.5 g (10 mol%) of α,ω-decanedicarboxylic acid, and 90 g of ethylene glycol were mixed with 68 g of titanium tetrabutoxide.
mg and reacted until the distillate amounted to 41 ml. The reaction product was placed in a 300 ml distillation column with stirring, and reacted in a bath at 260°C for 30 minutes under a nitrogen atmosphere. After distilling off the distillate mainly consisting of ethylene glycol, the pressure was gradually reduced and the pressure was gradually reduced for 30 minutes. After 200Pa or less, 1
After a period of time, the pressure was reduced to 50 Pa or less, and the distillate was distilled off to continue the reaction for increasing the degree of polymerization. The stirring speed was lowered as the internal viscosity increased, and was finally set at 0.5 rpm.
The intrinsic viscosity of the polymer taken out after carrying out the reaction under reduced pressure for 10 hours was 2.35 as measured with orthochlorophenol at 35°C. It was observed that the distillate was continuously distilled during the high vacuum reaction, and more than 50% of this distillate was analyzed by gas chromatography and was found to be a condensate of α,ω-decanedicarboxylic acid and ethylene glycol. It was confirmed that it was a cyclic ester. Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that 9.7 g (10 mol %) of isophthalic acid was used instead of α,ω-decanedicarboxylic acid. The intrinsic viscosity of the polymer after 10 hours was 1.72. Also,
Almost no distillate was observed 4 hours after the start of decompression. Example 2 and Comparative Example 2 The polymer obtained by reacting for 2 hours after the start of depressurization in Example 1 and Comparative Example 1 was placed in a molten state in a test tube with a diameter of about 2 cm, and the depth of the liquid was 1 cm, 2 cm, 3 cm, and 5 cm.
260℃ under reduced pressure of 50Pa or less.
The reaction was carried out without stirring. The degree of polymerization (P) is calculated from the intrinsic viscosity corresponding to each reaction time, and P∞ in the equilibrium state is calculated.
_Assuming ^that
Shown in the figure. It is clear from FIG. 1 that the α,ω-decanedicarboxylic acid copolymer reduces the effect of decreasing the degree of polymerization due to the depth of the liquid in an equilibrium state. Examples 3 to 5 A reduced pressure reaction was carried out for 10 hours in the same manner as in Example 1 except that equal moles of suberic acid, azelaic acid, and sebacic acid were used instead of α,ω-decanedicarboxylic acid. As a result, the intrinsic viscosity was 1.89 for suberic acid copolymerization, 1.98 for azelaic acid copolymerization, and 2.04 for sebacic acid copolymerization. Furthermore, in all cases, it was confirmed that distillates were present, albeit in small amounts, until the end of the polymerization reaction, and these distillates were found to contain large amounts of cyclic esters. Examples 6 to 8 and Comparative Examples 3 to 5 Example 1 when changing the dicarboxylic acid component and changing the amount of α,ω-decanedicarboxylic acid added
Polymerization results similar to those shown in Table 1 are shown in Table 1.

[Table] Examples 9-10 After reacting for 2 hours in Comparative Example 1, polystyrene or polycabrolactone (molecular weight approximately 2000)
After adding 10g of
Allowed time to react. The intrinsic viscosity of this material is 1.92 for polystyrene and 1.97 for polycabrolactone.
It was hot. ) Effects of the Invention As is clear from the comparison between Examples and Comparative Examples, by carrying out the present invention, it has become possible to produce high molecular weight polyesters by melt polymerization, which was previously thought to be impossible.

[Brief explanation of drawings]

When the degree of polymerization at melt polymerization reaction time t is P and the degree of polymerization at equilibrium is P∞, Figure 1 shows the relationship between (1/P ² _∞ ×10 ² ) and liquid depth (cm), and Figure 2 The figure shows the relationship between (1/P-1/P∞)×10 ⁶ and reaction time (hr). Line A in the figure is for isophthalic acid copolymerization, B is for α,ω-decanedicarboxylic acid copolymerization, C is isophthalic acid copolymerization at a liquid depth of 3 cm, and D is isophthalic acid copolymerization at a liquid depth of 1 cm. In the case, Ho is α, ω−
When the liquid depth is 3 cm for decane dicarboxylic acid copolymerization, the liquid depth is 1 cm for α, ω-decane dicarboxylic acid copolymerization.
This is the case.

Claims (1)

[Claims] 1. An intrinsic viscosity of 1.0 is obtained by melt polymerizing dicarboxylic acids, mainly aromatic dicarboxylic acids, and/or ester-forming derivatives thereof, and glycols, mainly ethylene glycol, and/or ester-forming derivatives thereof under reduced pressure. When producing the above polyester, a compound (A) that continuously generates a gaseous substance that does not substantially reduce the molecular weight of the polyester under polymerization conditions of 240 to 270°C is used at least at the stage where the intrinsic viscosity is 0.8 or more. A method for producing a high molecular weight polyester, characterized in that the polyester is present in a high molecular weight polyester.