JPS5818375B2 - Method for modifying transparent polyester molded products - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for modifying transparent polyester molded articles.

The purpose is to provide a polyester molded product having excellent transparency, chemical resistance, dimensional stability, and mechanical strength.

Conventionally, polyesters, particularly polyethylene terephthalate, have been used for various purposes such as fibers, films, and molded products because of their excellent mechanical properties, chemical resistance, and dimensional stability.

However, the crystallization rate of the polyester is extremely slow;
When a thick molded product is molded, crystallization occurs, which has the disadvantage that only an opaque molded product can be obtained.

In order to reduce this crystallization rate, attempts have been made to copolymerize polyethylene terephthalate with various third components, such as acid components such as isophthalic acid and glycol components such as neopentylene gelicol.

These modified polyethylene terephthalates can be made into transparent molded products by extrusion molding, injection molding, etc., but the resulting molded products have relatively low heat resistance and mechanical strength, and may deform during use. There is a problem.

As a result of intensive research to solve these problems, the present inventor found that the heat resistance and mechanical strength of transparent polyester molded products can be significantly improved by heat-treating the molded products at a specific temperature, This has led to the present invention.

That is, the present invention has a parallel transmittance at a thickness of 3 mm (integrating sphere turbidimeter Polyester molded products with a polyester molded product having a glass transition temperature of 50% or more (measured by
℃), T is the heat treatment temperature (℃)] This is a method for modifying a transparent polyester molded product, which is characterized by heat treatment at a temperature (T) expressed as follows.

The polyester used in the present invention has a thickness of 3
It is a transparent polyester with a parallel transmittance in mm of 50% or more.

The acid component of such polyester is mainly terephthalic acid and/or naphthalene dicarboxylic acid, but a portion (usually less than 50 mol%, preferably less than 30 mol%) of other difunctional carboxylic acids, e.g. Aromatic dicarboxylic acids such as isophthalic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, etc.;
Aliphatic dicarboxylic acids such as adipic acid, sepatic acid, etc.;
It may be replaced with one or more oxyacids such as oxybenzoic acid and ε-oxycaproic acid.

The naphthalene dicarboxylic acid includes 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid,
1,5-naphthalene dicarboxylic acid and the like are preferably used.

The glycol component includes compounds having two alcoholic hydroxyl groups, such as aliphatic compounds such as ethylene glycol, propylene glycol, trimethylene glycol, butanediol, neopentylene gelcol, hexanediol, decal diol, diethylene gelcol, etc. Glycol, alicyclic glycol such as cyclohexane dimethylol, tricyclodecanediol, etc., 2.2
- Aromatic diols such as bis(4-β-hydroxyethoxyphenyl)propane, 1,1-bis(4-β-hydroxyethoxyphenyl)cyclohexane, 4,4′-bis(β-hydroxyethoxy)diphenylsulfone, etc. Use.

These may be used alone or in combination of two or more, and a small proportion of a compound having two phenolic hydroxyl groups such as bisphenol A, bisphenol Z, etc. may be used in combination.

You can also do that.

The combination of the acid component and the glycol component is selected such that the resulting polyester has a parallel transmittance of 50% or more at a thickness of 9 mm.

For example, terephthalic acid is the acid component, and ethylene glycol.

2 to 90 mol%, and hineopentylene glycol 98 to
Copolymerized polyester with 10 mol% glycol component, 2,6-naphthalene dicarboxylic acid as acid component, ethylene glycol 50-99.4 mol% and hineopentylene glycol 0.6-50 mol% glycol component Examples include copolymerized polyesters made of terephthalic acid and 4,4'-bis(β-hydroxyethoxy)diphenylsulfone, and the like.

In particular, copolymerized polyesters in which ethylene terephthalate repeating units account for 10 to 98%, preferably 20 to 95% of the total repeating units and ethylene-2,6-naphthalene dicarboxylate repeating units account for 1 of the total repeating units.
Preference is given to copolyesters having a content of 0 to 99.4%, preferably 20 to 98%.

Among the acid components and glycol components, terephthalic acid (the main component is
・6-naphthalene dicarboxylic acid), isophthalic acid, 2,6-naphthalene dicarboxylic acid (when the main component is terephthalic acid), neopentylene gellicol, 4,4'-
bis(β-hydroxyethoxy)diphenylsulfone,
Particularly preferred are 2,2-bis(β-hydroxyethoxyphenyl)furopane, diethylene glycol, cyclohexane dimethylol, and the like.

Such polyester can be manufactured according to conventionally known polyester manufacturing methods.

For example, terephthalic acid or its ester-forming derivatives (
For example, lower alkyl esters such as methyl esters, phenyl esters, etc.) are reacted with ethylene glycol and hineopentylene glycol or their ester-forming derivatives to form bisglycol esters and/or
Alternatively, a low polymer thereof is formed, and the biscricol ester and/or the low polymer are subjected to a polycondensation reaction to obtain a polyester having a predetermined degree of polymerization.

In the present invention, the parallel transmittance at a thickness of 3 mvt is determined as follows.

3 on the light source side of the integrating sphere on the parallel light beam path of an integrating sphere turbidity meter (“Poitzk integrating sphere ultrafine turbidity meter” manufactured by Nippon Seimitsu Kogaku KK)
A plate-shaped sample with a thickness of mm is placed in close contact with the integrating sphere.

First, a reflector (specific reflectance -i100
) to block the light exit and measure the total light transmittance (Tt) of the sample. Next, remove the reflector from the optical path and calculate the parallel transmittance of the total light transmittance (Tt). Rate (T
trap only p) and measure the diffuse transmittance (Td),
The parallel transmittance (Tp) is calculated by the following formula: Tp=Tt - Td (%) In the present invention, it is necessary that the Tp of the polyester is 50% or more.

When Tp is lower than 50%, the transparency of polyester is low;
This makes it difficult to achieve the object of the present invention.

In the present invention, the transparent polyester molded product is heat-treated to improve the heat distortion temperature and mechanical strength of the molded product.

Heat treatment is performed using the following formula (%) [However, Tg is the glass transition temperature of the polyester molded product (
℃), T is the heat treatment temperature (℃)] Preferably Tg-30℃≦T<Tg (However, Tg and T are the same as defined above) More preferably Tg-25℃≦T<Tg (However, Tg and T is the same as the above definition).

If the heat treatment is carried out at a temperature lower than the lower limit of the above temperature range, the effect of the present invention will not be fully expressed, and if the heat treatment is carried out at a temperature higher than the upper limit of the above temperature range, the effect will not be sufficiently expressed and the polymer will crystallize. Both are undesirable because they may cause opacity and shrinkage of the molded product.

Although a treatment time of several minutes has some effect, it is preferable to set the treatment time to 30 minutes or more, more preferably 60 minutes or more.

The longer the treatment time, the more pronounced the effect, but the effect reaches an equilibrium value if the heat treatment is carried out for more than 1 day.

Heat treatment is usually carried out in a medium that does not attack the molded product.

As such a medium, for example, a liquid medium such as water, silicone oil, etc., or a gaseous medium such as air, nitric acid gas, etc. can be used.

The polyester referred to in the present invention includes one or more trifunctional or higher functional compounds, such as trimethylolpropane, chrycerin, pentaerythritol, trimesic acid, etc., and/or monofunctional compounds, such as benzoic acid, methoxypolyoxyethylene glycol, etc. The polymer is substantially linear and the parallel transmittance at a thickness of 37ftr/L is 5.
Copolymerization may be carried out to an extent of 0% or more.

In addition, additives such as stabilizers, pigments, fluorescent whitening agents, and colorants that are commonly used in the production of polyester may be included as necessary.

Further, the polyester molded product of the present invention can be obtained by a molding method such as injection molding, extrusion molding, blow molding, compression molding, or the like.

The molded product according to the present invention has a uniform interior,
Physical properties such as thermal deformation temperature, tensile strength, and bending strength are significantly improved, and transparency is excellent.

The transparent polyester molded product of the present invention can be used as a transparent plastic molded product such as transparent containers, instrument covers, road vehicle parts, etc.
It is useful for applications such as

The present invention will be described in detail below with reference to Examples.

Note that in the examples ('4 limiting viscosity (η) is the value measured at 35°C in orcyclophenol, and the heat distortion temperature is AST
It was measured by the method described in MD-648.

Moreover, the tensile yield strength was measured by the method described in ASTM D-638, and the bending strength was measured by the method described in ASTM D-790.

Furthermore, the glass transition temperature was measured using a PerkinElmer DSCI model at a heating rate of 10°C/min.

Examples 1 to 4 and Comparative Example 1 After drying polyethylene terephthalate (intrinsic viscosity [η) -0.67) copolymerized with 10 mol% isophthalic acid at 120°C for 3 hours, the cylinder temperature was 250°C and the mold temperature was Injection molding was performed at 30°C to obtain test pieces for measuring tensile yield strength, bending strength, and heat distortion temperature.

The parallel transmittance of the test piece at a thickness of 3 mm was 87%, and the glass transition temperature was 67°C.

Next, this test piece was heat treated in a hot air dryer at 50°C or 60°C for the time shown in Table 1.

Each physical property of the obtained test piece was measured.

The results are shown in Table 1 in comparison with those before heat treatment.

Incidentally, during the above heat treatment, no shrinkage or crystallization of the molded product was observed, and no loss of transparency was observed.

As is clear from Table 1, it can be seen that the physical properties of the samples after heat treatment are significantly improved compared to those before treatment.

Examples 5 to 7 and Comparative Examples 2 to 4 Polyethylene terephthalate copolymerized with 10 mol% neopentylene gellicol (intrinsic viscosity [η] -〇, 68)
After drying at 120℃ for 3 hours, the cylinder temperature was 250℃.
℃, and injection molding at a mold temperature of 30℃ to obtain test pieces for measuring tensile yield strength, bending strength, and heat distortion temperature.

The parallel transmittance of the test piece at a thickness of 3 mm was 85%, and the glass transition temperature was 68°C.

Next, this test piece was heat treated under the conditions shown in Table 2.

Each physical property of the obtained test piece was measured. The results are shown in Table 2 in comparison with those before heat treatment.

Comparative Example 3 Polyethylene terephthalate ([η)-0,65)< was injection molded at an injection temperature of 280°C and a mold temperature of 30°C to obtain molded products similar to Examples 1 to 5. It was whitened (equilibrium transmittance 0%) and lacked transparency.

Example 8 Polyethylene-2,6-naphthalene dicarboxylate copolymerized with 30 mol% of 4,4'-bis(β-hydroxyethoxy)cyphethoxy)diphenylsulfone (
After drying the intrinsic viscosity [η) = 0.63), the cylinder temperature is 2.
Injection molded at 80℃, mold temperature 40℃, tensile yield strength,
Test pieces for measuring bending strength and heat deformation temperature were obtained.

The parallel transmittance of the test piece at a thickness of 3 mm was 82%, and the glass transition temperature was 128°C.

When this test piece was subjected to a bending stress of 10 kg/cyst and held in boiling water, the test piece immediately began to deform.

Next, the above test piece was heat treated in silicone oil at 105°C for 30 minutes.

During this period, no shrinkage of the molded product or any other change in appearance was observed.

When this heat-treated test piece was held in boiling water under a bending stress of 10 kg/crA in the same manner as above, the heat-treated test piece did not deform at all even after 1 hour had passed.

Further, the heat deformation temperature of the heat treated test piece was 115°C.

Further, the heat-treated test piece was heated to 9.5% in silicone oil at 105°C.
When heat treated for a period of time, the heat distortion temperature rose to 126°C.

Claims (1)

[Scope of Claims] 1. 3 my thick, containing terephthalic acid and/or naphthalene dicarboxylic acid as the main acid component and a compound having two alcoholic hydroxyl groups as the main glycol component.
Parallel transmittance at n (measured using an integrating sphere turbidity meter)
Polyester molded products with a polyester molded product of 50% or more are calculated using the following formula (%) [However, Tg is the glass transition temperature of the polyester molded product (
℃), T is the heat treatment temperature (℃).