JPH07126364A - Low-permittivity polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester with a specified intrinsic viscosity and a stable low-permittivity by copolymerizing terephthalic acid or its deriv. with a diol component contg. a 2,2-dialkyl-1,3-propanediol. CONSTITUTION:A low-permittivity polyester with an intrinsic viscosity of 0.3-1.2dl/g is obtd. by copolymerizing an acid component contg. terephthalic acid and/or its deriv. with a diol component contg. a 2,2-dialkyl-1,3-propanediol (e.g. 2,2-diethyl-1,3-propanediol) pref. in an amt. of 3-50mol% of the diol component. Thus obtd. polyester has a stable low-relative permittivity, 3.1-2.4, in the frequncy range of 100-1GHz and exhibits changes in relative permittivity by moistening or water immersion for 1 week or longer and for less than 1 week of 0.2 or lower and 0.15 or lower, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low dielectric polyester used as a material for parts of electric equipment and electronic equipment. More specifically, it shows a stable low relative dielectric constant with no frequency dependence in daily conditions, and maintains a low relative dielectric constant even under high temperature and high humidity or after high temperature and high humidity treatment, and has a stable relative dielectric constant. A film having a dielectric constant,
The present invention relates to a low dielectric polyester useful for heat shrink films, heat fusion films, sheets and the like.

[0002]

2. Description of the Related Art Paper, cloth, mica, etc. have long been used as dielectric materials, but with the advent of various polymers, dielectric materials using polymer materials have been developed. Among these polymer materials, in addition to having excellent dielectric properties and electrical insulation, polyester that is relatively low in price, chemically stable, has high mechanical strength, and has excellent heat resistance and cold resistance is attracting attention. In recent years, this polyester has become the majority of dielectric materials. In addition to the polyester alone, which makes full use of the characteristics of polyester, there are many materials in which metals such as iron, copper, aluminum, and tin are laminated on the polyester film by vapor deposition or sputtering. It has been applied to capacitors when the rate is high, and mainly to films, printed wiring boards, and magnetic tapes when the rate is low.

Generally, for electric / electronic equipment materials, materials having a low relative dielectric constant have been favored as excellent materials. Generally, for expensive resins, a blending method of a fluorine-based compound, a fluorine-based polymer or the like has been widely used as a method for reducing the relative dielectric constant.

[0004]

However, conventional polyesters have a relatively high relative dielectric constant as a polymer, and as a measure for lowering the relative dielectric constant, polyesters have low dielectric constants such as fluorine compounds and plasticizers. A method of blending agents is possible, but the blended polyester is expensive,
Bleeds of low molecular weight blends are also a concern.

Further, conventional polyesters are easily hydrolyzed and deteriorated when they absorb moisture in water or in a hot and humid environment. As a result, the conventional polyester has impurities of hydrolyzate and water in the polyester resin after the water immersion treatment, under the high temperature and high humidity treatment or after the high temperature and high humidity treatment, and these impurities influence to significantly increase the relative dielectric constant. It was a problem.

The present invention provides a low dielectric polyester for which the above problems are solved.
To further describe, the low dielectric polyester provided is a single composition polyester for which blended products cannot be recognized, that is, a polyester composed of a certain composition ratio, and does not include a low dielectric additive (small molecule) and the like. Or, even if it contains, it is made of polyester whose additive is extremely difficult to qualitatively, has a stable low relative dielectric constant with no frequency dependence under ordinary conditions, and has high temperature and humidity or high temperature. It is an object of the present invention to provide a low-dielectric polyester having sufficiently stable dielectric properties, in which the relative permittivity hardly changes before and after the humid treatment.

[0007]

As a result of intensive studies by the present inventors, a polyester containing a specific 2,2-alkyl-substituted-1,3-propanediol as a copolymer component has excellent dielectric properties. After discovering this, we came to complete this discovery.

That is, the gist of the present invention is (1) a copolymerization reaction between an acid component containing terephthalic acid or / and a terephthalic acid derivative and a diol component containing 2,2-alkyl-substituted-1,3-propanediol. It is a low-dielectric polyester having an intrinsic viscosity of 0.3 to 1.2 dl / g, which is 2,2 in the diol component (2).
-Alkyl-substituted-1,3-propanediol 3-50
(3) 2,2-alkyl-substituted-1,3, which is a low dielectric polyester according to item (1), characterized in that it is mol%.
-A low dielectric polyester of the item (1), wherein the alkyl of propanediol is selected from ethyl, propyl, butyl, pentyl and hexyl, and (4) a low dielectric having stable low relative permittivity with little frequency dependence. Polyester, specifically, frequency 100 to 1 GHz
Has a low relative dielectric constant stable in the range of, preferably 10
It has a more stable low relative permittivity in the range of 0 to 1 MHz,
This low dielectric constant polyester is a low dielectric polyester according to item (1) having a low dielectric constant in the range of 3.1 to 2.4, and (5) a low dielectric polyester having a very small change in relative dielectric constant before and after humidification or water immersion treatment. Yes, specifically, in the frequency range of 100 to 1 MHz, the maximum change in relative permittivity does not exceed 0.2 in the case of humidification or water immersion treatment for 1 week or more, and the humidification or water immersion is performed for less than 1 week. The low dielectric polyester according to item (1), wherein the maximum change in relative permittivity is 0.15 or less in the case of treatment.

The diol component for obtaining the polyester of the present invention is a specific diol component and comprises a diol component containing 2,2-alkyl-substituted-1,3-propanediol. 2,2-alkyl-substituted-1, in the diol component
The molar ratio of 3-propanediol is preferably 3 to 50 mol%. That is, when the content of 2,2-alkyl-substituted-1,3-propanediol is less than 3 mol%, the viscosity decreasing effect of lowering the melt viscosity of the low dielectric polyester molded article is poor and stable production of the low dielectric polyester molded article is difficult. Moreover, the volume resistivity is remarkably decreased before and after the humidification or water immersion treatment, and the effect of the 2,2-alkyl-substituted-1,3-propanediol is difficult to be exhibited. Also, the molar ratio is 50 mol%
If it exceeds, the degree of polymerization of the polyester tends to be remarkably reduced and the strength as a molded article is lost.

2,2-Alkyl-substituted-1,3-propanediols are those whose alkyl is ethyl, propyl,
It is selected from the group of butyl, pentyl and hexyl. Specifically, 2,2-diethyl-1,3-propanediol (hereinafter referred to as DMP), 2-butyl-2-ethyl-
1,3-propanediol (hereinafter referred to as DMH), 2-
Pentyl-2-propyl-1,3-propanediol (hereinafter referred to as DMN), 2-butyl-2-hexyl-
An example is 1,3-propanediol (hereinafter referred to as DMU). These can be used alone or in any combination depending on the purpose of use.

2,2-Alkyl-substituted-1,3-propanediol is essential as the diol component for obtaining the polyester of the present invention, and ethylene glycol and the like are preferably used, but other components may be used as required. For example, polyols such as propylene glycol, butylene glycol, bisphenol A, neopentyl glycol, polyethylene glycol, polypropylene glycol, glycerin and pentaerythritol may be contained.

The acid component of the copolymerization for obtaining the polyester of the present invention is terephthalic acid or a terephthalic acid derivative such as terephthalic acid diester, terephthalic acid chloride or a mixture thereof, but as another component, the properties of polyester are used. Within a range that does not significantly change, for example, aromatic polycarboxylic acids such as isophthalic acid, orthophthalic acid, 1,2-bis (4-carbophenoxy) ethane, 2,6-naphthalenedicarboxylic acid, trimellitic acid, adipic acid, An aliphatic dicarboxylic acid such as sebacic acid or oxalic acid or a derivative such as an ester thereof may be contained as a copolymerization component.

As the copolymerization method for obtaining the polyester of the present invention, various ordinary methods can be used. For example,
A method of transesterifying dimethyl ester of dicarboxylic acid and diol to distill off methanol, and then gradually reducing the pressure to carry out polycondensation reaction under high vacuum, or an esterification reaction of dicarboxylic acid and diol to distill water. After giving out
A method in which the polycondensation reaction is carried out under a high vacuum by gradually reducing the pressure, or when a dimethyl ester of a dicarboxylic acid and a dicarboxylic acid are used together as a raw material, an ester exchange reaction between the dimethyl ester of a dicarboxylic acid and a diol is performed, and There is a method of performing an esterification reaction by adding an acid and then performing a polycondensation reaction at a high temperature. As the transesterification catalyst, manganese acetate, calcium acetate, zinc acetate or the like can be used, and as the polycondensation catalyst, known ones such as antimony trioxide, germanium oxide, dibutyltin oxide and titanium tetrabutoxide can be used.

Stabilizers can be added if desired. As the stabilizer, phosphoric acid compounds such as trimethyl phosphate and triphenyl phosphate, and hindered phenol compounds such as Irganox 1010 may be used.
Moreover, you may contain another additive.

Other additives can be added to the polyester, if desired, as long as the quality and properties are not changed. Examples of the additives include silicic acid compounds such as glass fibers for the purpose of improving mechanical strength, chloro compounds for aiming flame retardant effect, bromine compounds, and fluorine compounds for aiming at low dielectric constant and low absorption. Various conditions such as polymerization method, catalyst, stabilizer, etc. are not limited to the above examples.

The intrinsic viscosity of the polyester of the present invention is 0.
3 to 1.2 dl / g, preferably 0.5 to 0.8 dl /
g, particularly 0.55 to 0.75 dl / g is more preferable.
If the intrinsic viscosity exceeds 1.2 dl / g, the melt viscosity becomes too high and stains occur in the orifice, making stable production over a long period of time difficult. On the other hand, when it is less than 0.3 dl / g, the strength as a low dielectric polyester molded body is insufficient.

Surprisingly, the polyester of the present invention, despite having a water content of about 2000 ppm, heat-melts at 260 to 300 ° C. in the same manner as polyester dried to an extremely small amount of moisture of 50 to 200 ppm called absolutely dry. By extruding from a die and rapidly cooling and solidifying on a casting drum at 50 to 60 ° C., a low dielectric polyester molding can be processed into a sheet shape. After that, the sheet shape is heat-stretched into a film shape. As a stretching method, a tenter method of two-stage sequential biaxial stretching of longitudinal uniaxial stretching at 80 to 110 ° C., vertical and horizontal simultaneous or longitudinal stretching and lateral stretching is used. A tube method is possible as another stretching method. Further, the film shape is heat-treated at 110 to 200 ° C. These processing atmospheres may be under air, under an inert gas, under high vacuum, or under any combination of atmospheres.
The film-shaped film forming method is not limited to the above-mentioned method, and can be processed by a generally known calendering method or other film forming method. In this way, by using an arbitrary mold for polyester and selecting appropriate processing conditions, it is possible to obtain a low dielectric polyester molding suitable for the intended use without improving conventional processing machines. .

The low dielectric polyester thus obtained was transparent and had a small crystallinity, and its relative dielectric constant showed stable low dielectric properties in a wide frequency range. Further, the relative dielectric constant of this low dielectric polyester was stable after the water immersion treatment and after the high temperature and high humidity treatment or after the high temperature and high humidity treatment was almost unchanged from that before the treatment. By utilizing this excellent dielectric property, it is possible to provide a low dielectric polyester as a highly reliable component material for electric devices and electronic devices.

The reason why it has an excellent low relative dielectric constant is not clear, but the presence of the alkyl side chain contained in the 2,2-alkyl-substituted-1,3-propanediol, which is the copolymerization component of the polyester of the present invention. It can be inferred that the molecular structure became amorphous and the structure had a large free volume, and as a result, the charge was easily moved and the polyester exhibited a low relative dielectric constant.

Since this alkyl substitution is a side chain having so-called hydrophobicity, water in the resin reaches the ester bond in the main chain even after the water immersion treatment or under the high temperature humidification or after the high temperature humidification treatment. And prevent hydrolysis. Since the generation of impurities due to hydrolysis is small, it is considered that the increase in the relative permittivity can be extremely small after the water immersion treatment, under the high temperature humidification or after the high temperature humidification treatment.

[0021]

EXAMPLES Next, the present invention will be specifically described with reference to Examples. The physical property measurements shown in Examples and Comparative Examples were carried out as follows. (1) Molar ratio of diol component of polyester The molar ratio of diol component was determined by measurement of nuclear magnetic resonance spectrum. (2) Intrinsic viscosity Using a mixed solvent of phenol / tetrachloroethane (weight ratio 6/4), the drop time of the solution was measured and calculated at 30 ° C. (3) Moisture content The water content was measured by the Karl Fischer method using a trace water content measuring device.

(4) Crystallinity A flat panel camera was attached to the X-ray diffractometer, an X-ray transmission photograph was taken to examine the crystallinity, and the evaluation was performed as follows. A: Amorphous. B: Almost no crystallinity.
C: There is some crystallinity. (5) Relative permittivity: A tin foil main electrode with a diameter of 30 mm was made and 1
The film was measured after the following treatment at a frequency of 00 Hz, 1 kHz and 1 MHz. (A) Untreated (b) Immersion treatment Immersed in a water bath with a liquid temperature of 24 to 26 ° C. for 1, 7, and 14 days. (C) Constant Temperature and Humidity Treatment A constant temperature and constant humidity tank was used, and the temperature and humidity were kept at 50 ° C. and 90% relative humidity for 1 day, 7 days and 14 days. (6) Dielectric breakdown strength Measured in oil according to JIS C 2318.

Example 1 Dimethyl terephthalate (hereinafter referred to as DMT) 16.
1.8 mol of 2-butyl-2-ethyl-1,3-propanediol (hereinafter referred to as DMH) was mixed with 1 mol, and 0.01 mol of zinc acetate and 0.004 mol of antimony trioxide were used as catalysts. Use, under nitrogen stream, 200 ~ 205 ℃
After heating for 1 hour, 3.1 mol of methanol was distilled off. Next, ethylene glycol (hereinafter referred to as EG) 30.
After adding 4 mol, the mixture was heated for 6 hours to distill off 28.6 mol of methanol. Then, it is heated at 270 to 275 ° C. for 1 hour and further 280 under reduced pressure of about 0.3 to 0.5 Torr.
16 mol of excess diol was distilled off at ˜285 ° C., and polycondensation was carried out so that a predetermined intrinsic viscosity was obtained to obtain a polyester. The obtained polyester was made into pellets, and the diol component ratio, intrinsic viscosity and water content of the pellets were measured. Then, using an extruder in a vacuum atmosphere, the pellets are heated and melted at 270 to 285 ° C., extruded from a T-die into a sheet having a thickness of about 0.5 mm, and rapidly solidified by a casting drum at 60 ° C. to form a transparent sheet. Obtained. Using a biaxial stretching machine in a nitrogen gas atmosphere, this sheet is 90 to 1
The film was biaxially stretched at 10 ° C. at a stretching rate of 300% / min at a stretching ratio of 3 ×× 3 × simultaneously to obtain a low dielectric polyester film having a thickness of about 0.05 mm. About the obtained film,
After examining the crystallinity and measuring the intrinsic viscosity, the relative dielectric constant at each frequency and the strength of dielectric breakdown were measured. Next, after subjecting to water immersion treatment and constant temperature humidification treatment for a predetermined number of days, the relative dielectric constant was measured at each frequency. The measurement results are shown in Table 1.

Example 2 DMH was changed to 3.5 mol and EG was changed to 28.7 mol, and the amounts of alcohol distilled at this time were 6.1 mol and 25.6, respectively.
The procedure was carried out in accordance with Example 1 except that the amount was molar.

Example 3 DMH was replaced with 5.3 mol and EG was replaced with 26.9 mol, and the amounts of alcohol distilled at this time were 9.4 mol and 22.2, respectively.
The procedure was carried out in accordance with Example 1 except that the amount was molar.

Example 4 The procedure of Example 1 was repeated except that DMH was replaced with 2,2-diethyl-1,3-propanediol (hereinafter referred to as DMP).

Example 5 25.1 mol of EG and 7.1 mol of 2-pentyl-2-propyl-1,3-propanediol (hereinafter referred to as DMN) were used instead of DMH, and the amount of alcohol distilled off at this time was changed. Example 1 was repeated except that the amounts were 19.4 mol and 14.2 mol, respectively.

Comparative Example 1 DMH (16.1 mol) contains 32.2 mol of EG, 0.011 mol of zinc acetate as a catalyst, and 0.00 mol of antimony trioxide.
Heated at 200 to 205 ° C. under a nitrogen stream using 04 mol,
32.0 mol of methanol was distilled off. And 270
Heat at ~ 275 ° C for 1 hour, then about 0.3-0.5To
Under a reduced pressure of rr, 16 mol of excess diol was distilled off at 280 to 285 ° C., and polycondensation was carried out so that a predetermined intrinsic viscosity was obtained to obtain polyester and pelletized. Moisture content of pellet is 2
It was 100 ppm and the intrinsic viscosity was 0.78 dl / g.
The pellets were heat-melted by an extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C., and extrusion molding was attempted from a T die, but molding failure occurred, and the target film could not be obtained.

Comparative Example 2 The pellets obtained in Comparative Example 1 were dried to a water content of 150 ppm, and the target film was obtained according to Example 1.
The measured values of the obtained film are shown in Table 1.

Comparative Example 3 The procedure of Example 1 was repeated, except that neopentyl glycol (hereinafter referred to as NPG) was used instead of DMH.

The results are shown in Table 1. The viscosity change rate (* 1) in Table 1 was calculated by the following formula.

[Equation 1]

[0032]

[Table 1]

As can be seen from Table 1, the low dielectric polyester of the present invention has a higher electrical conductivity than the polyester of the comparative example.
It had a sufficient dielectric breakdown strength as an electronic material and exhibited a stable low relative permittivity even when the frequency was changed to 100 to 1 MHz in everyday conditions. Further, even after water immersion for 1 or 2 weeks or high temperature and high humidity treatment, the change in relative permittivity was small and stable. Further, in addition to the excellent dielectric properties, the decrease in the intrinsic viscosity, which is a measure of the molecular weight, is extremely small, so there is no concern about the decrease in the molecular weight after processing, and it is a transparent and good-feeling low-dielectric polyester film.

[0034]

In general, it is preferable that the electric and electronic materials have a low relative permittivity, but conventional polyesters have a relatively high relative permittivity as a polymer material. In addition, since conventional polyesters are easily hydrolyzed due to their chemical structure, an increase in the relative dielectric constant was observed after the water immersion treatment, or after the high temperature and high humidity treatment, and it was not stable.

On the other hand, the low-dielectric polyester of the present invention uses a polyester containing 2,2-alkyl-substituted-1,3-propanediol, so that it is stable and low in frequency in daily conditions. Allowed the appearance of polyester with dielectric properties. Further, surprisingly, the relative permittivity hardly changed even under the high temperature and high humidity condition or after the high temperature and high humidity condition, and the stable relative permittivity was exhibited. The excellent low dielectric polyester of the present invention is suitable for flexible printed circuit boards, magnetic tapes, capacitors and other molded articles.

Thus, the low dielectric polyester of the present invention has been found to have a stable low relative dielectric constant, which is not available in conventional polyesters, as a material useful for electric equipment, electronic equipment and the like. This low dielectric polyester is of great significance in the electric / electronic and communication fields as a new polyester material suitable for severe environments such as high temperature and high humidity.

Claims (5)

[Claims] 1. An acid component containing terephthalic acid or / and a terephthalic acid derivative and 2,2-alkyl-substituted-1,3.
A low dielectric polyester having an intrinsic viscosity of 0.3 to 1.2 dl / g, which is obtained by copolymerizing with a diol component containing propanediol. 2. The low dielectric polyester according to claim 1, wherein the 2,2-alkyl-substituted-1,3-propanediol in the diol component is 3 to 50 mol%. 3. The low dielectric polyester of claim 1, wherein the alkyl of the 2,2-alkyl-substituted-1,3-propanediol is selected from ethyl, propyl, butyl, pentyl and hexyl. 4. The low dielectric polyester according to claim 1, which has a stable low relative permittivity in a frequency range of 100 to 1 GHz, and has a relative permittivity of 3.1 to 2.4. 5. The maximum change in relative dielectric constant does not exceed 0.2 before and after humidification or water immersion treatment for one week or more, and the maximum change in relative dielectric constant does not exceed 0.2 after humidification or water immersion treatment for less than one week. The low dielectric polyester according to claim 1, which has a ratio of 15 or less.