JPS6148532B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polyester having a small amount of terminal carboxyl groups. More specifically, the present invention relates to a method for producing a polyester having a small amount of terminal carboxyl groups, which is characterized by reacting a substantially linear saturated polyester with a compound having a specific structure. Saturated linear polyesters, particularly polyethylene terephthalate, polytetramethylene terephthalate, etc., have excellent physical properties and are widely used as fibers, films, plastics, and the like. Among the physical properties of this polyester, it is known that the humidity and heat stability in particular depends on the amount of terminal carboxyl groups of the polyester, and the lower the amount of terminal carboxyl groups, the better the humidity and heat stability. For this reason, various methods for producing polyesters having a small amount of terminal carboxyl groups have been proposed. One method is to react the terminal carboxyl group of polyester with a specific compound, such as adding and reacting an epoxy compound such as phenyl glycidyl ether or N-glycidyl phthalimide; An example is a method of causing an addition reaction. However, the method using an epoxy compound has the disadvantage that the reactivity of the epoxy group with the terminal carboxyl group of the polyester is relatively low, and therefore a relatively long time is required for the reaction with the polyester, and the method using a carbodiimide has the problem of causing discoloration of the polymer. The present inventors have discovered that when a compound having a specific structure is reacted with a polyester, a polyester having fewer terminal carboxyl groups and less coloring can be obtained in an extremely short period of time, and has thus arrived at the present invention. That is, the present invention is characterized in that a substantially linear saturated polyester is reacted with a compound represented by the following general formula () in an amount of 0.1% to 5% by weight based on the saturated polyester. This invention relates to a method for producing polyester. [In the formula, R is a monovalent organic group, X is a divalent organic group,

The ring structure of the formula is a 5-membered ring or a 5-membered ring. ] As the acid component constituting the substantially linear saturated polyester referred to in the present invention, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, enyl ether dicarboxylic acid, methyl terephthalic acid,
Aromatic dicarboxylic acids such as methyl isophthalic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, etc.; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; ε-oxycaprone Examples include oxycarboxylic acids such as oxybenzoic acid and hydroxyethoxybenzoic acid, and among these, aromatic dicarboxylic acids, particularly terephthalic acid, are preferred. Moreover, in the above saturated polyester,
When the acid component is dicarboxylic acid, the glycol component includes ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol,
Examples include cyclohexane dimethylol, and among these, ethylene glycol and tetramethylene glycol are particularly preferred. It is also possible to use polyoxyalkylene glycol as part of the glycol component, such as polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, and copolymers thereof. When using polyoxyalkylene glycol, its average molecular weight is preferably from 500 to
5000, more preferably 600 to 4000, particularly preferably 800 to 3000, and the amount used is about 5 to 85% by weight in the copolyester, preferably 10
The amount to be copolymerized is about 80% by weight, more preferably about 15% to 75% by weight. The copolyester obtained by copolymerizing polyoxyalkylene glycol is preferably a block copolymer. In addition, the saturated polyester may be within a substantially linear range (for example, 1 mol % with respect to the total acid component).
(below), trifunctional or higher functional compounds such as trimethylolpropane, pentaerythritol, trimellitic acid, pyromellitic acid, etc., or monofunctional compounds such as benzoylbenzoic acid, diphenylcarboxylic acid, etc. may be copolymerized. . The degree of polymerization of the saturated polyester is such that the intrinsic viscosity of orthochlorophenol measured at 35° C. is preferably 0.4 or more, more preferably 0.45 or more, and particularly preferably 0.5 or more. In the present invention, the compound reacted with the above-mentioned saturated polyester is a compound represented by the following formula (). [In the formula, R is a monovalent organic group, X is a divalent organic group,

The ring structure of [Formula] is a 5-membered ring or a 6-membered ring. ] This compound has high reactivity with the terminal carboxyl groups of polyester, and in particular has the effect of reacting with the terminal carboxyl groups of the polyester under melting to reduce the concentration of the terminal carboxyl groups of the polyester in an extremely short period of time. . In the general formula (), R is a monovalent organic group, and this monovalent organic group has 1 to 10 carbon atoms.
Hydrocarbon groups such as alkyl groups having 5 to 12 carbon atoms, cycloalkyl groups having 5 to 12 carbon atoms, and aralkyl groups having 8 to 20 carbon atoms. Examples include an aliphatic unsaturated hydrocarbon group that does not cause oxidation, and an organic group having the aliphatic unsaturated hydrocarbon group. More specifically, alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, octyl, etc.; cycloalkyl groups include cyclopentyl,
Examples include cyclohexyl and the like. Examples of aliphatic unsaturated hydrocarbon groups that are stable at the melting temperature of polyester in an inert gas atmosphere include allyl groups and substituted allyl groups. Among these substituted allyl groups, metaallyl and crotyl groups are preferred. Furthermore, examples of the organic group having an aliphatic unsaturated group include those in which a portion of the hydrogen atoms of the above-mentioned hydrocarbon group is substituted with an unsaturated group such as an allyl group, a metaallyl group, or a crotyl group; , O, S, etc. (e.g., siasyl ring, isothiasyl ring, diphenyl ether residue, diphenyl sulfone residue, etc.), which have the above-mentioned unsaturated groups. can. In the general formula (), X is a divalent organic group, and

The ring structure of [Formula] can form a 5-membered ring or a 6-membered ring. Examples of such divalent organic groups include ethylene, substituted ethylene, trimethylene, and substituted trimethylene. In addition, the substituents of substituted ethylene and substituted trimethylene include alkyl groups having 1 to 10 carbon atoms, and 6 carbon atoms.
-12 aryl groups, C5-12 cycloalkyl groups, and C8-20 aralkyl groups. Among these X, ethylene and trimethylene are particularly preferred. Specific examples of the compound represented by the general formula () include 2-methoxy-2-oxazoline-2-
Ethoxy-2-oxazoline, 2-propoxy-
2-oxazoline, 2-butoxy-2-oxazoline, 2-pentyloxy-2-oxazoline,
2-hexyloxy-2-oxazoline, 2-heptyloxy-2-oxazoline, 2-octyloxy-2-oxazoline, 2-nonyloxy-
2-oxazoline, 2-decyloxy-2-oxazoline, 2-cyclopentyloxy-2-oxazoline, 2-cyclohexyloxy-2-oxazoline, 2-allyloxy-2-oxazoline, 2-methallyloxy-2-oxazoline,
Substituted oxyoxazoline compounds such as 2-crotyloxy-2-oxazoline; 2-methoxy-5,6-dihydro-4H,1,
3-Oxazine, 2-ethoxy-5,6-dihydro-4H, 1,3-oxazine, 2-propoxy-5,6-dihydro-4H, 1,3-oxazine, 2-butoxy-5,6-dihydro- 4H,
1,3-oxazine, 2-pentyloxy-5,
6-dihydro-4H,1,3-oxazine,2-
2-hexyloxy-5,6-dihydro-4H,
1,3-oxazine, 2-heptyloxy-5,
6-dihydro-4H, 1,3-oxazine, 2-
Octyloxy-5,6-dihydro-4H, 1,
3-Oxazine, 2-nonyloxy-5,6-dihydro-4H, 1,3-oxazine, 2-decyloxy-5,6-dihydro-4H, 1,3-oxazine, 2-cyclopentyloxy-5,6-dihydro -4H, 1,3-oxazine, 2-cyclohexyloxy-5,6-dihydro-4H, 1,
3-Oxazine, 2-allyloxy-5,6-dihydro-4H, 1,3-oxazine, 2-methallyloxy-5,6-dihydro-4H, 1,3-
Examples include substituted oxyoxazine compounds such as oxazine, 2-crotyloxy-5,6-dihydro-4H, and 1,3-oxazine. These compounds may be used alone or in combination with
You may use more than one species in combination. The compound represented by the general formula () is, for example, a compound represented by the following formula (). [In the formula, R' is a monovalent organic group, X' is a divalent organic group, and Y is C or Br. ] It can be easily synthesized by a ring-closing reaction accompanied by dehydrohalogenation using caustic soda or caustic potash. Moreover, as a synthesis method, not only the above-mentioned method but also other methods can be used as needed. In the general formula (), R' and X' correspond to R and X in the general formula (), respectively. The compound represented by the general formula () has high reactivity, reacts efficiently with the terminal carboxyl group of the saturated polyester, and can significantly reduce the concentration of the terminal carboxyl group. The amount of such compounds used is 0.1% to 5% by weight based on the saturated polyester. If the amount is less than 0.1% by weight, the desired effect of the present invention will not be noticeable, and if it exceeds 5% by weight, no further effects can be expected. The more preferred usage amount is 0.2
% to 4% by weight, particularly preferably 0.3% by weight
3% by weight. In the present invention, a saturated polyester and a predetermined amount of the compound represented by the above general formula () (hereinafter referred to as compound ()) are reacted, and the reaction method is to melt the saturated polyester and the compound (). A method in which a saturated polyester and a compound () are uniformly mixed while the polyester is melted, and after molding, the molded product is heat-treated to cause the unreacted compound () to react; Examples include a method in which the compound () is impregnated with the compound () and then heat-treated to cause the compound () to react, but the method described above is the most preferred. Further, the reaction temperature is preferably 150°C to 320°C, more preferably 200°C to 300°C, especially
240°C to 290°C is preferred. Furthermore, the reaction pressure may be increased pressure, but normal pressure or reduced pressure is preferred. The preferred reaction time varies depending on the reaction temperature, but
The time is about 30 seconds to 60 minutes, more preferably 1 minute to 30 minutes, particularly preferably 1 minute to 15 minutes. This reaction can be carried out not only by mixing and reacting the two in an ordinary polyester polymerization reactor with stirring, but also by mixing the two in an extruder, for example. For example, if they are mixed during yarn spinning, membrane formation, or plastic extrusion molding or injection molding, polyester fibers, films, and plastic molded products with a low carboxyl group content can be obtained. In the present invention, various additives such as an unexpected radiation absorber, a heat stabilizer, a flame retardant, Brighteners, lubricants, nucleating agents, mold release agents, pigments, fillers, etc. may be added. Hereinafter, the present invention will be explained in detail with reference to Examples. still,
All "parts" in the examples are "parts by weight."
means. In addition, the amount of terminal carboxyl groups is
A.Conix method (Makromol.Chem 26 226
(1958)). Examples 1 to 6 and Comparative Example 1 100 parts of polyethylene terephthalate with an intrinsic viscosity of 0.68 and a terminal carboxyl group weight of 38 equivalents/10 ⁶ g was melted at 280°C in a nitrogen stream, and a predetermined amount of the compound () shown in Table 1 was added. Made me react. Substantially no coloration of the polymer occurred during this reaction.
Table 1 shows the intrinsic viscosity and terminal carboxyl group equivalent of the polyester after 3 minutes. As a comparison, Table 1 also shows the case where the compound () is not added at all, but from Table 1, in the case of the present invention, the compound () reacts with the polyester under the melting condition of the polymer, and the terminal carboxyl of the polyester is It can be seen that the base amount is significantly reduced.

[Table] Examples 7 to 12 and Comparative Example 2 Intrinsic viscosity 0.74 and terminal carboxyl group equivalent 43 equivalents/10 ⁶ g of polytetramethylene terephthalate
A predetermined amount of the compound () shown in Table 2 was blended into 100 parts, and then heated to 240°C using an extruder.
A sheet was obtained by melt extrusion at a temperature of about 3 minutes at an average residence time of about 3 minutes. Table 2 shows the intrinsic viscosity and terminal carboxyl group equivalent of the obtained sheet. Table 2 also shows the case where compound () is not added at all, but Table 2 shows that the number of terminal carboxyl groups in this product increases, whereas when compound () is added and reacted as in the present invention. It can be seen that the terminal carboxyl group equivalent of the polyester is significantly reduced.

[Table] Example 13 and Comparative Example 3 Polyethylene terephthalate sheet approximately 500μ thick (intrinsic viscosity 0.64, terminal carboxyl group equivalent 32)
equivalent amount/10 ⁶ g) was immersed in a toluene solution in which about 2% by weight of 2-pentyloxy-2-oxazoline was dissolved at the reflux temperature of toluene for 30 minutes. Next, take out the sheet, dry it, and leave it in the air.
After heat treatment at 180℃ for 1 hour, the intrinsic viscosity was
0.61, terminal carboxyl group equivalent is 7 equivalents/10 ⁶ g
It became. As a comparison, when the sheet was heat-treated under the same conditions as above without being immersed in a toluene solution, the sheet had an intrinsic viscosity of 0.62 and a terminal carboxyl group equivalent of 36 equivalents/10 ⁶ .

Claims (1)

[Claims] 1. A substantially linear saturated polyester and a compound represented by the following general formula () in an amount of 0.1% to 5% by weight based on the saturated polyester. [In the formula, R is a monovalent organic group, X is a divalent organic group, and the ring structure of [Formula] is a 5-membered ring or a 6-membered ring. ] A method for producing a polyester with a small amount of terminal carboxyl groups, which is characterized by carrying out a reaction.