JP2555377B2 - Method for producing polyester resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has a relatively high glass transition temperature (hereinafter, referred to as “adhesive, paint, binder for ink, binder for thermal transfer image-receiving paper, etc.”) , Tg), and a method for industrially producing a high molecular weight polyester resin.

(Prior Art) A polyester resin containing aromatic dicarboxylic acid and dimer acid as main acid components, C _{2 to} C ₁₀ glycol as main glycol components, and polycaprolactone polyol and polycaprolactone diol has relatively low Tg. It is known from JP-B-58-47432 that it can be advantageously used as an adhesive or the like.

However, although such polyester resins have excellent properties at low temperatures, they are soft and often lack performance at high temperatures even when used together with a curing agent.

As described above, in particular, the copolyester resin in consideration of solvent solubility or solution fluidity often does not show a clear melting point. When an amorphous polyester resin having a low Tg and no melting point is used as an adhesive, the adhesive strength at high temperature is lacking. When used as a paint, the coating film shows tacking properties and when used as a binder for thermal transfer paper, Various problems such as lack of image stability after transfer occurred, and although the level varied depending on the application, there was often a demand for a polyester resin having a relatively high Tg.

(Problems to be Solved by the Invention) The present inventors have found that a polyester resin having a high Tg can be prepared by copolymerizing (A) or (B), and have previously proposed (special feature). No. 62-191268).

However, due to such a lot or copolymerization amount of (A) or (B), a high molecular weight polyester resin cannot be prepared, or even when it can be prepared, a relatively long polymerization reaction is required, and further, In some cases, the prepared polyester resin showed remarkable coloring.

An object of the present invention is to provide a method for stably preparing a polyester resin having a high molecular weight and a high Tg, which is obtained by copolymerizing (A) or (B).

(Means for Solving Problems) In view of the above situation, the present inventors have conducted extensive studies on a method for producing a polyester resin that does not have the above-mentioned problems, and as a result, are included in (A) or (B). The inventors have found that the above object can be achieved by controlling the amount of specific impurities introduced into the reaction system to be below a certain amount, and have reached the present invention.

That is, the present invention has an aromatic dicarboxylic acid as a main acid component and at least one selected from the group consisting of (A) represented by the following structural formula (I) and (B) represented by the following structural formula (II). (A) when producing a polyester resin whose main glycol component is
Alternatively, the amount of the phenolic hydroxyl group contained in (B) and brought into the reaction system is 1 equivalent% / total acid component or less, and a group formed by continuously adding two or more molecules of ethylene oxide to the phenolic hydroxyl group. (A) and / or (B) is selected and used so that the amount thereof is 10 equivalent% / total acid component or less, and is used as a gist.

In carrying out the method of the present invention, (A) and (B)
At least one selected from the group consisting of terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalene Aromatic dicarboxylic acids such as dicarboxylic acid and 5-tertiarybutylisophthalic acid are the main acid components, and ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol,
Polyester resin containing glycol component of 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, diethylene glycol, neopentyl glycol, cyclohexanedimethanol Copolymerize.

Usually, (A) and (B) are synthesized by adding ethylene oxide to bisphenol S or bisphenol A. In this reaction, depending on the reaction conditions, part of the phenol group of bisphenol S or bisphenol A may remain unreacted, or two or more molecules of ethylene oxide may be added to the phenol group. When a phenolic hydroxyl group is introduced into the reaction system,
Polycondensation reaction is inhibited.

Therefore, in the present invention, in order to prepare the target polyester resin, the amount of the phenolic hydroxyl group contained in (A) and (B) and introduced into the reaction system is 1 or less.
It should be controlled to be equal to or less than equivalent% / total acid component, preferably equal to or less than 0.5 equivalent% / total acid component.

Further, in the present invention, in order to prepare the target polyester resin, the amount of the group formed by continuously adding two or more molecules of ethylene oxide to the phenolic hydroxyl group exceeds 10 equivalent% / total acid component. Since it is not suitable for the purpose of copolymerizing (A) or (B) with (to improve the Tg of the polyester resin), it is necessary to keep it at 10 equivalent% / total acid component or less, preferably 5 equivalent% / total acid component or less. There is.

(A) or (B) is the target polyester resin
It is selected in the range of 5 to 95 mol% / total acid component depending on the required properties depending on the Tg and the use of the polyester resin.

The esterification reaction between an aromatic dicarboxylic acid and glycol is usually carried out under normal pressure or under pressure at 200 to 250 ° C, preferably 2
Perform at a temperature of 20-240 ° C. Even when a low polymerization polyester resin is prepared by transesterification using a lower alkyl ester of an aromatic dicarboxylic acid instead of an aromatic dicarboxylic acid, esters of n-butyl titanate, zinc acetate, calcium acetate, manganese acetate, etc. Although an exchange reaction catalyst is essential, the reaction takes place in a temperature range similar to the esterification reaction. Subsequent polycondensation reaction is performed under reduced pressure at 200-
At 300 ° C., preferably 220-280 ° C., a polycondensation catalyst such as n-butyl titanate, antimony trioxide, germanium oxide is used to prepare a polyester resin having a desired molecular weight.

In preparing the polyester resin by the method of the present invention, 1 part of the aromatic dicarboxylic acid is replaced with an aliphatic dicarboxylic acid such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, or p-oxybenzoic acid, 6
-Hydroxy-2-carboxynaphthalene and other oxy acids, or polyvalent carboxylic acids such as trimellitic acid, trimedic acid, and pyromellitic acid may be substituted, or a part of glycol may be replaced with trimethylolethane or trimethylol. It can be replaced with a polyhydric alcohol such as propane or pentaerythritol.

(Examples) Next, the present invention will be specifically described by showing Examples and Comparative Examples.

In the present invention, the molecular weight of the polyester resin is represented by the relative viscosity measured at 20 by dissolving in a concentration of 0.5 g / dl using a mixed solvent such as phenol / tetrachloroethane in a weight ratio.

The amount of phenolic hydroxyl group is (A) or (B)
Was dissolved in methanol and Varian VXR 300 type NMR was used to
The ¹ H-NMR spectrum was measured at a resonance frequency of 300 MHz, and the content thereof was calculated from the height of the peak [6.7 (or 7.6 PPM position in the case of (A)] at 6.7 and 7.6 PPM] attributed to the phenolic hydroxyl group, and the content thereof was calculated as (A) or ( The copolymerization amount of B) was converted into equivalent% with respect to all acid components.

Further, the amount of the group formed by continuously adding two or more molecules of ethylene oxide to the phenolic hydroxyl group is (cp) -8000 high performance liquid chromatograph manufactured by Toyo Soda Co., Ltd. by dissolving (A) or (B) in tetrahydrofuran. Using the graph, determine the content from the height of the peak attributed to the compound containing the group formed by consecutively adding two or more molecules of ethylene oxide to the phenolic hydroxyl group, and copolymerize (A) or (B). The amount is shown in terms of equivalent% to the total acid component.

The Tg of the polyester resin was measured at a temperature rising rate of 20 ° C./minute using a DSC II type differential lens scanning / calorimeter made by Perkin Elmer.

Example 1, Comparative Example 1 The raw materials shown in Table 1 were put in a stainless steel reaction can in the amounts shown in Table 1, and the esterification reaction was carried out at 230 ° C. for 3 hours under normal pressure.
Preparation of low-polymerization degree polyester, and then addition of antimony trioxide 2.0 × 10 ^-4 mol / mol of total acid component as polycondensation catalyst to prepare polyester resin with relative viscosity 1.40 at 275 ° C. under reduced pressure of 0.5 mmHg. Polycondensation reaction was carried out to prepare the polyester resins shown in Table 1.

 The abbreviations in Table 1 are as follows.

TPA: terephthalic acid IPA: isophthalic acid EG: ethylene glycol A: bisphenol S ethylene oxide (2 molecules) adduct …… 0.15 equivalent% phenolic hydroxyl group content B: bisphenol A ethylene oxide (2 molecules) adduct …… Content of phenolic hydroxyl group 0.2 equivalent% A ': Bisphenol S ethylene oxide (2 molecules)
Adduct: phenolic hydroxyl group content 2.5 equivalent% C: Bisphenol A ethylene oxide (4 molecules) adduct: phenolic hydroxyl group content 0.1 equivalent% Example 2 Same as No. 3 of Example 1, but The esterification reaction conditions were set as shown in Table 2 to prepare a low degree of polymerization polyester, and then polycondensation reaction was performed to obtain the results shown in Table 2.

Comparative Example 2 Similar to No. 1 of Comparative Example 1, except that esterification reaction conditions were set as shown in Table 3 to prepare a low-polymerization degree polyester, followed by polycondensation reaction, the results shown in Table 3 were obtained. Obtained.

From the comparison between Example 1 and Comparative Example 1, the amount of the phenolic hydroxyl group derived from (A) or (B) brought into the reaction system was 1 equivalent% / total acid component or less, preferably 0.5 equivalent% /
It is apparent that a high polymerization degree (high relative viscosity) polyester obtained by copolymerizing (A) or (B) can be easily produced by controlling the total acid component to be equal to or less than that. Furthermore, in copolymerizing (A) or (B) for the purpose of improving the Tg of polyester resin, when the group formed by continuously adding two or more molecules of ethylene oxide to the phenol hydroxyl group is copolymerized, the most ethylene oxide addition is obtained. Even in the case of a two-molecule adduct having a small amount, if the content is 10 equivalent% or more, the purpose of improving Tg will not be met.

From the comparison between Example 2 and Comparative Example 2, if the amount of the phenolic hydroxyl group present at the start of the reaction is 1 equivalent% / total acid component or less, the esterification reaction time for preparing the low degree of polymerization polyester is adjusted to the reaction temperature. It is clear that the Tg of the polyester resin can be shortened and the total reaction time can be shortened to prepare a polyester resin having a high degree of polymerization by prolonging according to the above.

(Effect of the Invention) According to the method of the present invention, it is possible to prepare a polyester resin having a high molecular weight and a high Tg in a relatively short time.

The obtained polyester resin is suitable for adhesives, paints, binders for inks, binders for thermal transfer paper, and the like.

Claims (1)

(57) [Claims] 1. An aromatic dicarboxylic acid as a main acid component,
At least one selected from the group consisting of an ethylene oxide adduct of bisphenol S represented by the following structural formula (I) (A) and an ethylene oxide adduct of bisphenol A represented by the following structural formula (II) (B) In producing a polyester resin containing a seed and an aliphatic glycol as a main glycol component, the amount of the phenolic hydroxyl group contained in (A) or (B) and brought into the reaction system is 1 equivalent% / total acid component or less. , And 2 for phenolic hydroxyl groups
Production of a polyester resin characterized in that (A) and / or (B) is selected and used so that the amount of groups formed by continuous addition of ethylene oxide of a molecule or more is 10 equivalent% / total acid component or less. Method.