JP3753061B2 - Production method of copolyester - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a copolyester used for molding materials, adhesives, paints, coating agents and the like, and in particular, in a batch system, a divalent carboxylic acid or a lower ester thereof, a dihydric alcohol and a trivalent or higher valence. The present invention relates to a method for producing a copolyester having a broad molecular weight distribution and a high hydroxyl value from a polyhydric alcohol.
[0002]
[Prior art]
Copolyester has many excellent properties compared to polyester composed of a single component, and thus has been put to practical use in molding materials, adhesives, paints, coating agents and the like. In order to industrially produce such a copolyester by a batch method, a glycol ester of a polyfunctional carboxylic acid and / or a low polymer thereof is usually obtained from an ester former of a polyfunctional carboxylic acid and a glycol. A method in which a polyfunctional carboxylic acid is esterified with an unreacted glycol and then a polycondensation reaction is carried out by heating the resulting product under reduced pressure. A method is employed in which an ester and / or a low polymer thereof is obtained, and the resulting product is heated under reduced pressure to cause a polycondensation reaction.
[0003]
When the copolyester obtained as described above is used for adhesives, etc., it is necessary to have a wider molecular weight distribution than the polyester molecular weight distribution obtained by the conventional reaction method in order to improve the adhesion performance. There is.
In addition, as shown in JP 2000-8018 A, when an isocyanate compound is reacted after synthesis of a polyester resin in order to improve the adhesion performance of the polyester resin, the hydroxyl value falls within a predetermined range. It will be necessary to make adjustments. However, since the conventional production method cannot be controlled to increase the hydroxyl value of the polyester, the hydroxyl value may be so low that it cannot be used as a raw material for the adhesive.
[0004]
[Problems to be solved by the invention]
The present invention provides a production method capable of broadening the molecular weight distribution of the resulting copolymerized polyester resin and increasing the hydroxyl value of the copolymerized polyester as compared with conventional methods for producing a copolymerized polyester. To do.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have obtained a copolymer polyester having a wide molecular weight distribution and a high hydroxyl value by changing the method of charging the trifunctional or higher polyhydric alcohol used. The present inventors have found out that it is possible to complete the present invention.
That is, the present invention condenses a polyvalent carboxylic acid or a lower ester thereof, a dihydric alcohol and a trihydric or higher polyhydric alcohol to convert the trihydric or higher polyhydric alcohol to 0.1 to 5 with respect to the dihydric alcohol. When producing a copolyester having reacted by mol%, trihydric or higher polyhydric alcohol is divided into two or more steps and subjected to esterification reaction or transesterification reaction. In the process, polycarboxylic acid or its lower ester, dihydric alcohol, and a part of trihydric or higher polyhydric alcohol are reacted, and the esterification reaction or transesterification reaction in each process is advanced by 60% or more, and the final process In the above, the remainder of the trihydric or higher polyhydric alcohol is added to cause esterification reaction or transesterification reaction. Exchange reaction is the preparation of copolyester and performing polycondensation in advanced stages of 70% or more.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The raw material of the copolyester in the present invention is a polyvalent carboxylic acid or a lower ester thereof, a dihydric alcohol, and a trihydric or higher polyhydric alcohol.
○ Polyvalent carboxylic acid and its lower ester Preferred polyvalent carboxylic acids are aromatic dicarboxylic acids having 2 to 15 carbon atoms, alicyclic dicarboxylic acids, aliphatic dicarboxylic acids and the like. Similarly to the above, it can be used as a raw material in the present invention.
Preferred aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic anhydride, α-naphthalenedicarboxylic acid, β-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, and 5-potassium sulfoisophthalic acid, and preferred alicyclic dicarboxylic acids. Examples of the acid include 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and preferable aliphatic dicarboxylic acids include oxalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecylenic acid, There is dodecanedioic acid.
Also, polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid can be used in combination as long as gelation does not occur during polyester production.
[0007]
Dihydric alcohol Preferred dihydric alcohols are C2-C15 aliphatic glycols, alicyclic glycols and aromatic glycols.
Preferred aliphatic glycols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol. 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methylpentanediol, 2,2,3-trimethylpentanediol, diethylene glycol, triethylene glycol, dipropylene glycol, etc. There are 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol as preferable alicyclic glycols, and bisphenol A and the like as preferable aromatic glycols.
[0008]
O Trivalent or higher polyhydric alcohol In the present invention, the trifunctional or higher polyhydric alcohol used as a part of the polyhydric alcohol is a polyester cross-linking agent, and a preferred polyhydric alcohol is a fatty acid having 3 to 15 carbon atoms. Is a polyhydric alcohol. Preferable specific examples include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like.
The reaction ratio of the trihydric or higher polyhydric alcohol in the present invention is 0.1 to 5 mol% with respect to the dihydric alcohol. When it exceeds 5 mol%, there is a problem that gelation occurs during the production of the copolyester, and when it is less than 0.1 mol%, the effect of widening the molecular weight distribution of the copolyester cannot be exhibited.
[0009]
O Esterification reaction or transesterification reaction The production method of the present invention is characterized in that a trihydric or higher polyhydric alcohol is divided and reacted.
That is, a trihydric or higher polyhydric alcohol is divided into two or more steps to undergo esterification reaction or transesterification, and in each step immediately before the first step to the last step, the polyvalent carboxylic acid or its lower ester , Dihydric alcohol, and a part of trihydric or higher polyhydric alcohol are reacted, and the esterification reaction or transesterification reaction in each step is allowed to proceed by 60% or more. Is added to cause esterification reaction or transesterification reaction, and polycondensation is performed when the esterification reaction or transesterification reaction in the final step has progressed by 70% or more.
The preferable total amount of the trihydric or higher polyhydric alcohol reacted in the steps from the first step to the final step is 30 to 90% by weight of the total amount of the trihydric or higher polyhydric alcohol.
In the case where the reaction charge of polyhydric alcohol having a valence of 3 or more is less than 30% by weight or more than 90% by weight, the molecular weight distribution of the copolyester is adjusted in order to approach a normal reaction method in which raw materials are charged all at once. There is a possibility that the effect of increasing the hydroxyl value of the copolyester cannot be obtained.
[0010]
When the polyhydric alcohol is divided and charged, it is desirable to move to the next step and charge the polyhydric alcohol when the esterification reaction rate or transesterification reaction rate in the previous step becomes 60% or more.
If the esterification reaction rate and / or the transesterification reaction rate is less than 60%, there is a possibility that the effect of broadening the molecular weight distribution of the copolymerized polyester or increasing the hydroxyl value cannot be obtained.
[0011]
In the production method of the present invention, a preferable charge ratio of polyhydric alcohol (including dihydric alcohol) to polycarboxylic acid is 1.05 to 4 equivalents of polyhydric alcohol per equivalent of polycarboxylic acid. When this ratio is less than 1.05, the acid value of the reaction solution becomes high due to the influence of the residual carboxylic acid, and the polycondensation reaction time becomes long, or the production problem that the polymerization does not proceed to a predetermined degree of polymerization occurs. . On the other hand, if it is larger than 4, the excess glycol must be removed in the polycondensation reaction step, which may make it difficult to produce the polyester economically.
[0012]
This esterification and / or transesterification reaction can be performed by employing conditions generally used in polyester production. That is, while removing water and / or alcohol at 150 to 270 ° C. in the presence of no catalyst or esterification catalyst and / or transesterification catalyst such as metal compounds such as organic titanium compounds, organic tin compounds, and organic zinc compounds. Esterification reaction or transesterification reaction is performed.
[0013]
Next, the obtained polyvalent carboxylic acid ester and / or its low polymer is subjected to a polycondensation reaction to obtain a copolyester. The polycondensation reaction is carried out when the esterification reaction or transesterification reaction has progressed 70% or more. When the esterification reaction rate or the transesterification reaction rate is less than 70%, problems such as a long polycondensation reaction and a tendency for polymerization not to reach a predetermined degree of polymerization are likely to occur.
This polycondensation reaction can be carried out by employing conditions generally used in the production of polyester. That is, a method of polymerizing while removing excess glycol under reduced pressure (generally 1.3 kPa or less) at 230 to 270 ° C. in the presence of a polycondensation reaction catalyst such as an organic titanium compound, an organic tin compound, and an antimony compound. Can be adopted.
[0014]
In carrying out the method of the present invention, stabilizers, modifiers, colorants and the like can be arbitrarily used as necessary.
[0015]
[Action]
Although the detailed mechanism by which the molecular weight distribution of the copolyester is widened by the method of the present invention is unknown, the inventor presumes as follows.
That is, by dividing and reacting a trihydric or higher polyhydric alcohol, the reaction proceeds between the polyhydric alcohol and a polyester oligomer having a high molecular weight, resulting in a decrease in the intermediate molecular weight region in the molecular weight distribution of the copolymer polyester. The proportion of the high molecular weight region increased.
Moreover, as a result of increasing the degree of branching, the residual ratio of terminal hydroxyl groups increased, and the hydroxyl value of the copolyester increased.
[0016]
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
【Example】
[Example 1]
A 2 L flask was charged with 162.0 g of dimethyl terephthalic acid, 67.2 g of ethylene glycol, 109.0 g of neopentyl glycol, 0.71 g of trimethylolpropane (60% by weight of the total amount used), and 0.18 g of zinc acetate, The ester exchange reaction was carried out while distilling off the methanol generated by heating at a normal pressure of 150 to 210 ° C. over a period of 2.5 hours while stirring with a stirrer and a packed rectification column attached. Since the reaction rate based on the generated methanol was 92%, 155.7 g of isophthalic acid and a residual amount of trimethylolpropane of 0.48 g were added and the temperature was raised to 210 to 240 ° C. over 2.0 hours under normal pressure. The esterification reaction was carried out while distilling off water generated by heating with warm. Since the reaction rate based on the generated water was 88%, the esterification reaction was terminated.
Next, 0.1 g of antimony trioxide was added and subjected to a polycondensation reaction at 265 ° C. under a reduced pressure of 130 Pa, and the melt flow rate (measured at 190 ° C. according to JIS-K-6760-1977 was measured in g / A copolyester having a value expressed in 10 minutes) of 7 g / 10 min was obtained.
The molar composition ratio of polyvalent carboxylic acid by H ¹ -NMR analysis of this resin was terephthalic acid / isophthalic acid = 47/53, and the molar composition ratio of polyhydric alcohol was ethylene glycol / neopentyl glycol / trimethylolpropane = 43.0. /56.5/0.5, measured by GPC (gel permeation chromatography), and converted to standard polystyrene, the number average molecular weight Mn is 22,901, and the weight average molecular weight Mw is 64, Since it was 958, molecular weight distribution Mw / Mn was 2.84. Moreover, the hydroxyl value of this copolyester was 6.1 mgKOH / g.
[0017]
[Comparative Example 1]
Except that trimethylolpropane was charged all at once, an esterification reaction was carried out under the same reaction conditions as in Example 1 to obtain a resin having the same analysis result and melt flow rate by H ¹ -NMR analysis. The molecular weight measured by GPC (gel permeation chromatography) of this copolymerized polyester and calculated in terms of standard polystyrene was a number average molecular weight Mn of 23,000 and a weight average molecular weight Mw of 62,259. The molecular weight distribution Mw / Mn was 2.71. Moreover, the hydroxyl value of this copolyester was 4.9 mgKOH / g.
[0018]
[Example 2]
A 2 L flask was charged with 179.0 g of terephthalic acid, 66.0 g of ethylene glycol, 151.3 g of neopentyl glycol, and 4.27 g of trimethylolpropane (88% by weight of the total amount used), and a stirrer and a packed rectification column The esterification reaction was carried out while distilling off the water generated by heating at 170 to 250 ° C. under normal pressure over 5.0 hours while stirring. Since the reaction rate based on the generated water was 81%, 109.7 g of isophthalic acid, 78.6 g of sebacic acid, and 0.58 g of the remaining amount of trimethylolpropane were added, and the generated water was taken over 2.0 hours. The esterification reaction was carried out while distilling off. Since the reaction rate based on the generated water was 92%, the esterification reaction was terminated.
Next, 0.2 g of antimony trioxide was added and subjected to a polycondensation reaction at 245 ° C. under a reduced pressure of 130 Pa to obtain a melt flow rate (measured according to JIS-K-6760-1977 at a measurement temperature of 190 ° C. in g / A copolyester having a value expressed in 10 minutes) of 10 g / 10 min was obtained.
The molar composition ratio of the acid component of this resin by H ¹ -NMR analysis was terephthalic acid / isophthalic acid / sebacic acid = 51/31/18, and the molar composition ratio of the glycol component was ethylene glycol / neopentyl glycol / trimethylolpropane = 35. /63.5/1.5, measured by GPC (gel permeation chromatography), and converted to standard polystyrene, the number average molecular weight Mn was 22,160, and the weight average molecular weight Mw was 168. Since it was 650, molecular weight distribution Mw / Mn was 7.61. Moreover, the hydroxyl value of this copolyester was 7.4 mgKOH / g.
[0019]
[Comparative Example 2]
Except that trimethylolpropane was charged all at once, an esterification reaction was carried out under the same reaction conditions as in Example 1 to obtain a resin having the same analysis result and melt flow rate by H ¹ -NMR analysis. The molecular weight measured by GPC (gel permeation chromatography) of this copolymerized polyester and calculated in terms of standard polystyrene was 22,130 for the number average molecular weight Mn and 164,881 for the weight average molecular weight Mw. The molecular weight distribution Mw / Mn was 7.45. Moreover, the hydroxyl value of this copolyester was 6.9 mgKOH / g.
[0020]
【The invention's effect】
By the production method of the present invention, the molecular weight distribution of the obtained copolymer polyester resin can be broadened and the hydroxyl value of the copolymer polyester can be increased as compared with the conventional method for producing a copolymer polyester.

Claims (2)

 Copolymer obtained by condensing polyhydric carboxylic acid or its lower ester, dihydric alcohol and trihydric or higher polyhydric alcohol to react the trihydric or polyhydric alcohol with 0.1 to 5 mol% with respect to dihydric alcohol. In the production of the polymerized polyester, trivalent or higher polyhydric alcohols are divided into two or more steps and subjected to esterification reaction or transesterification reaction. The acid or its lower ester, a dihydric alcohol, and a part of a trihydric or higher polyhydric alcohol are reacted, and the esterification reaction or transesterification reaction in each step proceeds by 60% or more. The remainder of the polyhydric alcohol is added to cause esterification or transesterification, and the esterification or transesterification in the final step is 70. Preparation of copolyester and performing polycondensation in advanced stages or more. The total amount of the polyhydric alcohol of trivalent or more is reacted in a step before the final step from the first step, according to claim 1, characterized in that 30 to 90% by weight of the trihydric or higher polyhydric alcohols total amount A process for producing a copolyester.