U.S. patent application number 10/244032 was filed with the patent office on 2003-04-03 for polyester resin and resin composition for molding, and formed product thereof.
This patent application is currently assigned to TOYO BOSEKI KABUSHIKI KAISHA. Invention is credited to Iritani, Osamu, Nishida, Mitsuo.
Application Number | 20030065070 10/244032 |
Document ID | / |
Family ID | 19107306 |
Filed Date | 2003-04-03 |
United States Patent
Application |
20030065070 |
Kind Code |
A1 |
Nishida, Mitsuo ; et
al. |
April 3, 2003 |
Polyester resin and resin composition for molding, and formed
product thereof
Abstract
In a saturated polyester resin or a composition with the
saturated polyester resin as the main component for molding, the
melt viscosity at 200.degree. C. is at least 5 dPa.multidot.s and
not more than 1000 dPa.multidot.s, and the product a.times.b is at
least 500 where a (N/cm.sup.2) is the tensile breaking strength and
b (%) is the tensile breaking elongation of a film shape formed
product. Preferably, the polyester resin has a glass transition
temperature of not more than -10.degree. C., a melting point of at
least 70.degree. C. and not more than 200.degree. C., and an ester
group concentration of at least 1000 equivalents/10.sup.6 g and not
more than 8000 equivalents/10.sup.6 g. A material superior in water
resistance, electrical insulation, durability, working environment
and productivity as a molding material for an electric electronic
component having a sophisticated configuration is provided.
Inventors: |
Nishida, Mitsuo; (Ohtsu-shi,
JP) ; Iritani, Osamu; (Ohtsu-shi, JP) |
Correspondence
Address: |
Barry E. Bretschneider
Morrison & Foerster LLP
Suite 300
1650 Tysons Boulevard
McLean
VA
22102
US
|
Assignee: |
TOYO BOSEKI KABUSHIKI
KAISHA
Osaka-shi
JP
|
Family ID: |
19107306 |
Appl. No.: |
10/244032 |
Filed: |
September 16, 2002 |
Current U.S.
Class: |
524/121 ;
524/222; 528/272 |
Current CPC
Class: |
C08G 63/16 20130101;
C08G 63/189 20130101; C08G 63/672 20130101; C08G 63/183
20130101 |
Class at
Publication: |
524/121 ;
524/222; 528/272 |
International
Class: |
C08K 005/20; C08K
005/48; C08G 063/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 2001 |
JP |
2001-283880 |
Claims
What is claimed is:
1. A saturated polyester resin for molding, wherein a melt
viscosity at 200.degree. C. is at least 5 dPa.multidot.s and not
more than 1000 dPa.multidot.s, and a product a.times.b is at least
500 where a (N/cm.sup.2) is a tensile breaking strength and b (%)
is a tensile breaking elongation of a film shaped formed
product
2. A saturated polyester resin for molding, wherein a glass
transition temperature is not more than -10.degree. C. and a
melting point is at least 70.degree. C. and not more than
200.degree. C.
3. A saturated polyester resin for molding, wherein an ester group
concentration of a polyester is at least 1000 equivalents/10.sup.6
g and not more than 8000 equivalents/10.sup.6 g.
4. A saturated polyester resin for molding, wherein at least 2 mole
% of a diol component of a polyester is a polyalkylene glycol when
total amounts of a diol component of the polyester is 100 mole
%.
5. The saturated polyester resin for molding according to claim 4,
wherein said polyalkylene glycol is a polytetramethylene glycol
having a number-average molecular weight of at least 400 and not
more than 10000.
6. A saturated polyester resin for molding, wherein at least 2 mole
% of a diol component of a polyester is an aliphatic and/or
alicyclic diol having at least 10 carbon atoms when total amounts
of a diol component of the polyester is 100 mole %.
7. A saturated polyester resin for molding, wherein at least 2 mole
% of a dicarboxylic acid component of a polyester is an aliphatic
and/or alicyclic dicarboxylic acid having at least 10 carbon atoms
when total amounts of a dicarboxylic acid component of the
polyester is 100 mole %.
8. The saturated polyester resin for molding according to any of
claims 1-7 wherein at least 60 mole % of a dicarboxylic acid
component is terephthalic acid and/or naphthalene dicarboxylic
acid, and at least 40 mole % of a diol component is 1,4-butanediol
and/or ethylene glycol when respective total amounts of a
dicarboxylic acid component and a diol component of the polyester
are 100 mole %.
9. A polyester resin composition for molding, including at least
50% by weight of a saturated polyester resin defined in any of
claims 1-7 with respect to the entire composition.
10. A polyester resin composition for molding, including a
saturated polyester resin defined in any of claims 1-7 and an
antioxidant.
11. A polyester resin composition for molding, wherein a retention
of a melt viscosity after a heat treatment test at 121.degree. C.
and 0.2 MPa for 100 hours is at least 70% to the melt viscosity
before being subjected to the heat treatment test.
12. A polyester resin composition for molding, wherein a melt
viscosity at 200.degree. C. is 5 to 1000 dPa.multidot.s, and a
product a x b is at least 500 where a (N/cm.sup.2) is a tensile
breaking strength and b (%) is a tensile breaking elongation of a
film shaped formed product.
13. A formed product using a saturated polyester resin for molding
defined in any of claims 1-7.
14. A formed product using a polyester resin composition for
molding defined in claim 9.
15. A formed product using a polyester resin composition for
molding defined in claim 10.
16. A formed product using a polyester resin composition for
molding defined in claim 11 or 12.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to polyester resins and resin
compositions directed to molding, and a formed product using the
same. The polyester resins and resin compositions of the present
invention are particularly suitable for low pressure molding
applications to secure electrical electronic components in a
waterproof manner.
[0003] 2. Description of the Background Art
[0004] Electrical electronic components widely used in the field of
vehicles and electrical appliances must be electrically insulated
in order to achieve the usage objective. For example, electric
wires are covered with a resin that has electrical insulation.
Reflecting the growing demand for incorporating many more
sophisticated electrical components in a restricted small region
such as cellular phones during the past several years, various
approaches for electrical insulation thereof have been employed.
Particularly in the case where resins and the like corresponding to
an electrical insulator are to be molded for a product that has a
complicated configuration such as a circuit board, a technique to
be consistent with the critical configuration is required. For this
purpose, the technique of reducing the viscosity of the resin
during covering is generally employed. One known method of reducing
the viscosity is to impregnate the electrical electronic component
with a resin that is dissolved in a solvent to take a liquid form,
and then vaporizing the solvent. However, this method had various
problems such as bubbles remaining when the solvent is vaporized as
well as degrading the working environment if an organic solution is
used as the solvent.
[0005] Conventionally, a two-part epoxy resin has been used in view
of also the durability after molding, as disclosed in various
publications such as Japanese Patent Laying-Open No.2000-239349 and
EP 0 307 665 A2. Specifically, a base resin and a curing agent are
mixed immediately before the molding process at a predetermined
ratio, molded at low viscosity, warmed and then left for several
days to promote cure reaction and be completely solidified.
However, it is known that this method imposes various problems such
as the adverse effect of the epoxy towards the environment,
requiring accurate adjustment of the mixing ratio of the two
liquids, and the short available period of time prior to mixing
being restricted to only one to two months. Low productivity is
also noted due to the requirement of a cure period of several days
for hardening. Furthermore, there was a problem of the stress
caused by contraction in the resin after curing being concentrated
at an area where the physical strength is relatively weak such as
at the solder portion bonding an electrical electronic component
and the wiring to cause delamination thereat.
[0006] As a substitute for the two-part epoxy resin that has been
conventionally used despite the above-described problems, the hot
melt type resin can be cited as the resin for molding. The problems
associated with the working environment based on the usage of the
solvent containing type and epoxy based type are overcome in the
hot melt adhesive that requires only the resin to be heated and
melted in order to reduce the viscosity for molding. Since the hot
melt type resin is solidified by just being cooled after molding to
express its capability, the productivity is increased. Because it
is noted that a thermoplastic resin is generally employed,
recycling of the material when ended as a product is allowed by
heating and removing the resin by melting. The reason why a hot
metal type resin having high potentiality as a resin for molding
has not become the material to replace the conventionally-used
two-part epoxy resin is due to the fact that a base material
suitable therefor has not been proposed.
[0007] For example, the relatively economic EVA (Ethylene Vinyl
Acetate) which is known as a hot melt type has insufficient heat
resistance and durability in the environment where an electrical
electronic component is used. The inclusion of various additives to
express adhesion may contaminate the electrical electronic
component to reduce the electrical performance. Thus, EVA is not
suitable. Polyamide that is another hot melt type has high adhesion
towards various substrates as a resin without any additives, and is
suitable as a resin material for low-pressure molding by virtue of
its low melt viscosity and high cohesive force, as disclosed in,
for example, EP 1 052 595 B1. However it is known that polyamide is
basically highly hygroscopic and will gradually absorb moisture.
Electrical insulation which is one of the most important property
is often degraded over time.
[0008] Polyester that has high electrical insulation and water
resistance can be thought of as an extremely useful material for
the present application. However, the melt viscosity is generally
high. During the molding process for a sophisticated component, an
injection molding step at a high pressure of at least several
thousand N/cm.sup.2 will be required. There is a possibility of the
electrical electronic components being fractured during the molding
process.
[0009] Thus, a base material that meets the requirements of various
capabilities as a resin for molding directed to electrical
electronic components having complicated configurations was not
conventionally proposed.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a base
material that meets the requirements of various capabilities such
as waterproof, electrically insulation, working environment,
productivity, durability and the like for a polyester resin or a
resin composition for molding directed to an electrical electronic
component having a sophisticated configuration.
[0011] To achieve the above object, the present invention includes
a polyester resin for molding, a resin composition for molding, and
a formed product using the same.
[0012] According to an aspect, the present invention is a saturated
polyester resin for molding, wherein the melt viscosity at
200.degree. C. is at least 5 dPa.multidot.s and not more than 1000
dPa.multidot.s, and the product of a x b is at least 500, where a
(N/mm.sup.2) is the tensile breaking strength and b (%) is the
tensile breaking elongation of a film-shape formed product.
[0013] According to another aspect, the present invention is a
saturated polyester resin for molding, wherein the glass transition
temperature is not more than -10.degree. C., and the melting point
is at least 70.degree. C. and not more than 200.degree. C.
[0014] According to a further aspect, the present invention is a
saturated polyester resin for molding, wherein the ester group
concentration of polyester is at least 1000 equivalents/10 g and
not more than 8000 equivalents/10.sup.6 g.
[0015] According to still another aspect, the present invention is
a saturated polyester resin for molding, wherein at least 2 mole %
of a diol component of polyester is a polyalkylene glycol when
total amounts of a diol component of the polyester is 100 mole %.
Preferably, the polyalkylene glycol is a polytetramethylene glycol
having a number-average molecular weight of at least 400 and not
more than 10000.
[0016] According to a still further aspect, the present invention
is a saturated polyester resin for molding, wherein at least 2 mole
% of a diol component of polyester is an aliphatic and/or alicyclic
diol having at least 10 carbon atoms when total amounts of a diol
component of the polyester is 100 mole %.
[0017] According to yet a further aspect, the present invention is
a saturated polyester resin for molding, wherein at least 2 mole %
of a dicarboxylic acid of polyester is an aliphatic and/or
alicyclic dicarboxylic acid having at least 10 carbon atoms when
total amounts of a dicarboxylic acid component of the polyester is
100 mole %.
[0018] Preferably in the above aspect, at least 60 mole % of the
dicarboxylic acid is a terephthalic acid and/or naphthalene
dicarboxylic acid, and at least 40 mole % of the diol component is
a 1,4-butanediol and/or ethylene glycol when respective total
amounts of the dicarboxylic acid component and the diol component
of the polyester are 100 mole %.
[0019] In the above aspect, the present invention is preferably a
polyester resin composition for molding, including at least 50% by
weight of a saturated polyester resin among the entire amount.
Also, the present invention is preferably a polyester resin
composition for molding, including the above saturated polyester
resin and an anti-oxidant.
[0020] According to yet another aspect, the present invention is a
polyester resin composition for molding, wherein the retention of
the melt viscosity after a heat treatment test for 100 hours at
121.degree. C. and 0.2 MPa is at least 70% to the melt viscosity
prior to being subjected to the heat treatment test.
[0021] According to yet a still further aspect, the present
invention is a polyester resin composition for molding, wherein the
melt viscosity at 200.degree. C. is at least 5 dPa.multidot.s and
not more than 1000 dPa.multidot.s, and the product of a.times.b is
at least 500 where a (N/mm.sup.2) is the tensile breaking strength
and b (%) is a tensile breaking elongation of a film-shape formed
product.
[0022] Also, the present invention is preferably a formed product
using a saturated polyester resin or a polyester resin composition
for molding of the above respective aspects.
[0023] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] "Molding" in the present specification refers to molding
injected at the low pressure of 10 N/cm.sup.2 to 800 N/cm.sup.2.
The molding process is carried out at an extremely low pressure as
compared to injection molding carried out at a high pressure of the
average of approximately 4000 N/cm.sup.2 conventionally employed
for general plastic molding. The principle is similar to that of
general injection molding, wherein a melted resin is injected to a
mold cavity in which an electrical electronic component is set to
encapsulate the component. Over molding can be effected without
fracturing the delicate component.
[0025] The polyester resin for molding of the present invention has
a melt viscosity of at least 5 dPa.multidot.s and not more than
1000 dPa.multidot.s at 200.degree. C. These values of the melt
viscosity at 200.degree. C. have been measured as set forth below.
A sample dried to 0.1% or below in moisture was used. The viscosity
when a polyester resin heated and stabilized at 200.degree. C. was
passed through a die having a hole diameter of 1.0 mm and a
thickness of 10 mm under the pressure of 98N/cm.sup.2 with a flow
tester available from Shimadzu Corporation (Part No. CFT-500C).
Although high resin cohesive force and durability can be achieved
when the melt viscosity becomes as high as 1000 dPa.multidot.s or
above, there is a possibility of the component being fractured
since injection molding of high pressure is required for molding of
a sophisticated configuration. By using a polyester for molding
having a melt viscosity of not more than 1000 dPa.multidot.s,
preferably not more than 500 dPa.multidot.s, a molded component
superior in electrical insulation can be obtained at a relatively
low injection pressure of several hundred N/cm.sup.2. The property
of the electrical electronic component is not degraded. Although a
lower value of melt viscosity at 200.degree. C. is preferable, the
lower limit is at least 5 dPa.multidot.s, preferably at least 10
dPa.multidot.s, more preferably at least 50 dPa.multidot.s, and
most preferably at least 100 dPa.multidot.s taking into
consideration the adhesion and cohesive force of the resin.
[0026] In order to conduct molding while minimizing thermal
degradation of the polyester, rapid melting from 210.degree. C. to
220.degree. C. is required. Therefore, it is desirable that the
upper limit of the melting point is 200.degree. C. The upper limit
is preferably 190.degree. C., and more preferably 180.degree. C.
The lower limit is to be set to 5.degree. C. to 10.degree. C.
higher than the heat resistant temperature required in the
corresponding application. Taking into consideration the ease in
handling at ordinary temperature and the normal heat resistance,
the lower limit is at least 70.degree. C., further preferably at
least 100.degree. C., more preferably at least 120.degree. C.,
particularly preferably at least 140.degree. C., and most
preferably at least 150.degree. C.
[0027] The tensile breaking strength and elongation of the
polyester of the present invention were measured at 50% RH
atmosphere at 23.degree. C., based on a film formed product under
thermal pressing. Specifically, a polyester resin dried to 0.1% or
below in moisture was sandwiched between two polyethylene fluoride
sheets and pressed for 10 seconds at 200.degree. C., and then
rapidly cooled down to ordinary temperature to obtain a polyester
film. At this stage, it is desirable that a spacer, if necessary,
is used to adjust the thickness to 0.2 mm. A sample 50 mm in length
and 15 mm in width was cut out from such a film. The tensile
breaking strength and elongation of the present invention were
measured by subjecting this sample under the conditions of distance
of 30 mm between the chucks and the tensile rate of 50 mm/min. in a
50% RH atmosphere at 23.degree. C. Here, the product a.times.b is
at least 500 where a (N/cm.sup.2) is the tensile breaking strength
and b (%) is the tensile breaking elongation. Preferably, the
product a.times.b is at least 1000, further preferably at least
2000, and most preferably at least 2500. If the product a.times.b
is less than 500, sufficient durability may not be achieved with
respect to various impacts that will be received in various use
conditions. Although the upper limit is not particularly limited,
the upper limit is preferably not more than 20000, more preferably
not more than 15000, and most preferably not more than 12000 taking
into consideration the resin distortion towards the interior
electronic component.
[0028] If the tensile breaking strength is too low, the electrical
electronic component may not be held at the sufficient strength,
inducing the possibility of being detached or the like. Preferably,
the tensile breaking strength a is at least 2 (N/cm.sup.2). Also,
if the tensile breaking elongation is too low, the resin may be
brittle and not capable of withstanding the mechanical load on the
electrical electronic component, inducing the possibility of a
crack or the like in the resin. Therefore, the tensile breaking
elongation b is preferably at least 200 (%).
[0029] In order to express low melt viscosity that is absent in the
general polyester such as PET and PBT in engineering plastics, as
well as heat resistance and durability of a level equal to that of
two-part epoxy resins, the aliphatic based and/or alicyclic and
aromatic based compositions must be adjusted. For example, in order
to retain high heat resistance of at least 150.degree. C., a
polyester copolymer based on terephthalic acid and ethylene glycol,
terephthalic acid and 1,4-butanediol, naphthalene dicarboxylic acid
and ethylene glycol, or naphthalene dicarboxylic acid and
1,4-butanediol is suitable. Since mold releasability due to rapid
crystal solidification after molding is particularly desirable from
the standpoint of productivity, the polyester copolymer is
preferably based on terephthalic acid and 1,4-butanediol, or
naphthalene dicarboxylic acid and 1,4-butanediol, both of rapid
crystallization.
[0030] As to the terephthalic acid and naphthalene dicarboxylic
acid, the sum of either one or both thereof is preferably at least
60 mole %, more preferably at least 70 mole %, and further
preferably at least 80 mole % in the dicarboxylic acid component.
Also, as to the ethylene glycol and 1,4-butanediol, the sum of
either one or both is preferably at least 40 mole %, more
preferably at least 45 mole %, further preferably at least 50 mole
%, and most preferably at least 55 mole % in the diol
component.
[0031] When the total sum of the entire dicarboxylic acid component
and entire diol component is 200 mole %, the total amount of the
terephthalic acid and 1,4-butanediol or the naphthalene
dicarboxylic acid and 1,4-butanediol is preferably at least 120
mole %, more preferably at least 130 mole %, further preferably at
least 140 mole %, and most preferably at least 150 mole %. If the
total amount is less than 120 mole %, the crystallization rate is
reduced, whereby the mold releasability will be degraded. Also, the
total amount of the terephthalic acid and 1,4-butanediol or the
naphthalene dicarboxylic acid and 1,4-butanediol is preferably not
more than 180 mole %, and more preferably not more than 170 mole %.
If the total amount thereof exceeds 180 mole %, the crystallization
rate becomes so high that distortion during contraction easily
occurs to reduce the adherence towards the electrical electronic
component.
[0032] As a copolymer component applying adhesion to the base
composition that achieves the above-described high heat resistance,
an aliphatic or alicyclic dicarboxylic acid such as adipic acid,
azelaic acid, sebacic acid, 1,4-cyclohexane dicarboxylic acid, 1,
3-cyclohexane dicarboxylic acid, 1, 2-cyclohexane dicarboxylic
acid, 4-methyl-1,2-cyclohexane dicarboxylic acid, or an aliphatic
or alicyclic diol such as 1,2-propanediol, 1,3-propanediol,
1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol,
1,5-pentane diol, 1,6-hexane diol, 3-methyl-1,5-pentane diol,
neopentyl glycol, diethylene glycol, dipropylene glycol,
2,2,4-trimethyl-1,3-pentane diol, cyclohexane dimethanol,
tricyclodecane dimethanol, hydroxy pivalic acid neopentyl glycol
ester, 1,9-nonane diol, 2-methyl octane diol, 1,10-dodecane diol,
2-butyl-2-ethyl-1,3-propane diol, and polyoxy methylene glycol can
be enumerated.
[0033] By achieving copolymerization of an aliphatic or alicyclic
dicarboxylic acid having at least 10 carbon atoms such as a dimer
acid or hydrogenated dimer acid and a derivative thereof, or an
aliphatic or alicyclic diol having at least 10 carbon atoms such as
a dimer diol or hydrogenated dimer diol, the glass transition
temperature can be lowered while maintaining the high melting
point. Therefore, from the standpoint of achieving both heat
resistance of the polyester resin and adherence towards the
electrical electronic component, it is preferable that these are
included as the dicarboxylic acid component or diol component in
copolymerization. A derivative of the aliphatic or alicyclic
dicarboxylic acid refers to a derivative of carboxylic acid and
that can be a copolymer component, such as ester, acid chloride or
the like.
[0034] In the present specification, a dimer acid refers to an
aliphatic or alicyclic dicarboxylic acid generated by an
unsaturated fatty acid being converted into a dimer by
polymerization or Diels-Alder reaction and the like (in addition to
most dimers, many include several mole % of a trimer, a monomer, or
the like). A hydrogenated dimer acid refers to hydrogen added to
the unsaturated bonding portion of the above dimer acid. A dimer
diol or hydrogenated dimer diol refers to a reduction of the two
carboxylic acids of the relevant dimer acid or hydrogenated dimer
acid to hydroxyl groups. As a dimer acid or dimer diol, EMPOL or
SOVERMOL from Cognis Corporation or PRIPOL from Uniqema can be
enumerated.
[0035] A small amount of aromatic based copolymer component may
also be used if the melt viscosity is maintained at a low range.
For example, an aromatic dicarboxylic acid such as isophthalic acid
and orthophthalic acid, and an aromatic based glycol such as
ethylene oxide additions and propylene oxide additions of bisphenol
A can be enumerated. From the standpoint of mold releasability, it
is particularly preferable to introduce in blocks an aliphatic
based component of relatively high molecular weight such as
polytetramethylene glycol that exhibits rapid crystal
solidification after molding. Also, copolymerization of a monomer
that has a high molecule weight is preferable from the standpoint
of facilitating rapid crystal solidification. Specifically, the
above cited dimer acid, hydrogenated dimer acid, a derivative
thereof, dimer diol, hydrogenated dimer diol and the like are
suitable.
[0036] Introduction of such polymers in blocks improves the heat
cycle durability due to reduction in the glass transition
temperature as well as the hydrolyzable resistance due to reduction
in the ester group concentration. Therefore, this approach is
particularly preferable when durability after molding is important.
In the present specification, "heat cycle durability" refers to the
capability to be absent of resin delamination and resin cracks at
the interface region with an electronic component or the like that
differs in the coefficient of linear expansion when repeatedly
subjected to temperature change between a high temperature and a
low temperature. Delamination and generation of cracks will easily
occur if the modulus of elasticity of the resin is increased during
cooling. In order to provide a base material that can withstand the
heat cycle, the glass transition temperature is preferably not more
than -10.degree. C., more preferably not more than -20.degree. C.,
further preferably not more than -40.degree. C., and most
preferably not more than -50.degree. C. Although the lower limit is
not particularly cited, at least -100.degree. C. can be cited for
practical usage taking into consideration adhesion and the
anti-blocking capability.
[0037] In order to achieve hydrolyzable resistance that can
withstand the vapor of high temperature in view of the achievement
of durability over a long period of time, it is desirable that the
upper limit of the ester group concentration is not more than 8000
equivalents/10.sup.6 g. The upper limit of the ester group
concentration is preferably not more than 7500 equivalents/10.sup.6
g, and more preferably not more than 7000 equivalents/10.sup.6 g.
In order to ensure the chemical resistance (gasoline, engine oil,
alcohol, general purpose solvent and the like) as a polyester, it
is desirable that the lower limit is at least 1000
equivalents/10.sup.6 g. The lower limit is preferably at least 1500
equivalents/10.sup.6 g, and more preferably at least 2000
equivalents/10.sup.6 g. In the present specification, the ester
group concentration is a value calculated from the composition and
the copolymer ratio of the polyester resin represented in
equivalent mole per 1000 kg of resin.
[0038] For the introduction of polymers in blocks, the dimer acid,
hydrogenated dimer acid, dimer diol, hydrogenated dimer diol,
polytetramethylene glycol and the like are preferably at least 2
mole %, more preferably at least 5 mole %, further preferably at
least 10 mole %, and most preferably at least 20 mole %. The upper
limit is not more than 70 mole %, preferably not more than 60 mole
%, and more preferably not more than 50 mole % taking into
consideration the heat resistance and handleability of blocking.
The number-average molecular weight of the polytetramethylene
glycol is preferably at least 400, more preferably at least 500,
further preferably at least 600, and particularly preferably at
least 700. The upper limit is preferably not more than 10000, more
preferably not more than 6000, further preferably not more than
4000, and most preferably not more than 3000. If the number-average
molecular weight of the polytetramethylene glycol is below 400, the
heat cycle durability and hydrolyzable resistance may be degraded.
In contrast, if the number-average molecular weight exceeds 10000,
the compatibility with the polyester portion will be degraded to
render copolymerization in blocks difficult.
[0039] The number-average molecular weight of polyester is
preferably at least 3000, more preferably at least 5000, and
further preferably at least 7000. The upper limit of the
number-average molecular weight is preferably not more than 50000,
more preferably not more than 40000, and further preferably not
more than 30000. If the number-average molecular weight is below
3000, the product of a.times.b cannot easily satisfy the defined
value. If the number-average molecular weight exceeds 50000, the
melt viscosity at 200.degree. C. may become higher.
[0040] The polyester resin for molding of the present invention is
a saturated polyester resin that does not contain an unsaturated
group. In the case of an unsaturated polyester, there is a
possibility of crosslinking or the like occurring during melting to
degrade the melt stability during molding.
[0041] As a method of determining the composition and composition
ratio of the polyester resin of the present invention, .sup.1H-NMR
and .sup.13C-NMR measuring a polyester resin dissolved in a solvent
such as chloroform deuteride, an assay by gas chromatography that
measures after methanolysis of the polyester resin and the like can
be cited. Particularly, .sup.1H-NMR is simple and convenient.
[0042] The well known methods can be employed for the preparation
of the polyester resin of the present invention. For example, the
polyester of interest can be obtained by subjecting the above
dicarboxylic acid and diol component to an esterification reaction
at 150.degree. C. to 250.degree. C., and then effecting
polycondensation at 230.degree. C. to 300.degree. C. while reducing
the pressure. Alternatively, the polyester of interest can be
obtained by subjecting the above-described derivative of dimethyl
ester of the dicarboxylic acid and the diol component to
transesterification at 150.degree. C. to 250.degree. C., and then
effecting polycondensation at 230.degree. C. to 300.degree. C.
while reducing the pressure.
[0043] For the purpose of improving the adhesion, flexibility,
durability and the like, the polyester resin for molding of the
present invention can be blended with a polyester of another
composition, another resin such as polyamide, polyolefine, epoxy,
polycarbonate, acryl, ethylene vinyl acetate, phenol and the like,
a curing agent such as an isocyanate compound, melamine, or the
like, a filler such as talc and mica, a pigment such as carbon
black, titanium oxide or the like, and a flame retardant such as
antimony trioxide, polystyrene bromide or the like to be used in
the application of molding as a resin composition. In this case,
the polyester resin is included at least 50% by weight, more
preferably at least 60% by weight, further preferably at least 70%
by weight, and particularly preferably at least 90% by weight with
respect to the entire composition. If the amount of the polyester
is below 50% by weight, the fastening adhesion, various durability,
water resistance for a good electrical electronic component,
inherent to the polyester resin, may be degraded.
[0044] In the case where the polyester resin or resin composition
of the present invention is exposed to high temperature for a long
period of time for molding, it is preferable to add an antioxidant.
For example, as a hindered phenol type, 1,3,5-tris
(3,5-di-t-butyl-4-hydroxybenzyl) isocyanrate, 1,1,3-tri
(4-hydroxy-2-methyl-5-t-butylphenyl) butane, 1,1-bis
(3-t-butyl-6-methyl-4-hydroxyphenyl) butane, 3,5-bis (1,1-dimethyl
ethyl)-4-hydroxy benzene propanoic acid, penta erytrityl tetrakis
(3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3-(1,1-dimethyl
ethyl)-4-hydroxy-5-methyl-benzene propanoic acid, 3,9-bis
[1,1-dimethyl-2-[(3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy]
ethyl]-2,4,8,10-tetraoxaspiro [5.5] undecane,
1,3,5-trimethyl-2,4,6-tris (3',5'-di-t-butyl-4'-hydroxybenzyl)
benzene, as a phosphorus type, 3,9-bis (p-nonyl
phenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane,
3,9-bis (octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5]
undecane, tri (monononylphenyl) phosphite, triphenoxy phosphine,
isodecyl phosphite, isodecyl phenyl phosphite, diphenyl
2-ethylhexyl phosphite, dinonyl phenyl bis (nonylphenyl) ester
phosphorus acid, 1,1,3-tris (2-methyl-4-ditridecyl
phosphite-5-t-butylphenyl) butane, tris (2,4-di-t-butylphenyl)
phosphite, pentaerythritol bis (2,4-di-t-butylphenyl phosphite),
2,2'-methylene bis (4,6-di-t-butylphenyl) 2-ethylhexyl phosphite,
bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite,
and as a thioether type, 4,4'-thiobis [2-t-butyl-5-methylphenol]
bis [3-(dodecylthio) propionate], thiobis
[2-(1,1-dimethylethyl)-5-methyl-4,1- -phenylene] bis
[3-(tetradecylthio)-propionate], pentaerythritol tetrakis
(3-n-dodecylthio propionate), bis (tridecyl) thiodipropionate can
be enumerated, all which can be used singularly, or in composite.
The added amount thereof is preferably at least 0.1% and not more
than 5%. If the added amount is less than 0.1%, the effect of
preventing thermal degradation will be inferior. If the added
amount exceeds 5%, the adhesion or the like may be adversely
affected.
[0045] It is desirable that the retention of the melt viscosity of
the polyester resin composition of the present invention after a
heat treatment test for 100 hours at 121.degree. C. and 0.2 MPa is
at least 70% to the melt viscosity prior to being subjected to the
heat treatment test. In the heat treatment test of the present
invention, a resin or a composition thereof for molding is cut to a
dimension of 1 cm.times.1 cm.times.1 cm, and processed under the
condition of 121.degree. C..times.0.2 MPa.times.100 hours. The melt
viscosity retention thereof is preferably at least 75%, more
preferably at least 80%, and most preferably at least 90%. There is
no restriction in the upper limit, and a value closer to 100% is
favorable. If the retention of the melt viscosity is below 70%, the
durability when used at high temperature may be degraded.
[0046] The polyester resin or resin composition for molding of the
present invention is poured into a die in which an electrical
electronic component is set and then molded. More specifically, the
polyester resin or resin composition of the present invention is
heated in a heat tank at approximately 130-220.degree. C. to melt,
poured into a die through an injection nozzle, cooled down for a
predetermined period of time, and then taken out from the die as a
formed product.
[0047] Although the equipment for molding is not particularly
limited, Mold-man 8000 available from The Cavist Corporation of
USA, WS102/MX3006 available from Nordson Corporation of Germany,
and DYNAMELT series available from ITW Dynatec of USA can be
cited.
[0048] The present invention will be described in further detail
based on examples. Respective measurements in the examples have
been obtained as set forth below. The ester group concentration is
a value calculated from the composition and copolymer ratio of the
polyester resin represented in equivalent mole per 1000 kg of
resin.
[0049] MELTING POINT, GLASS TRANSITION TEMPERATURE: Using a
differential scanning calorimeter "DSC220 Type" available from
Seiko Instruments Inc., an under-measurement specimen 5 mg was
placed in an aluminum pan and sealed with the lid pressed. The
specimen was held for five minutes at 250.degree. C. to be
completely melted, and then rapidly cooled with liquid nitrogen,
followed by an increase in temperature from -150.degree. C. to
250.degree. C. at the rate of 20.degree. C./min. for measurement.
The inflection point of the obtained curve was taken as the glass
transition temperature, and the endothermic peak was taken as the
melting point.
[0050] MELT VISCOSITY: Using a flow tester (CFT-500C type)
available from Shimadzu Corporation, a cylinder located at the
center of a heating unit set to 200.degree. C. was filled with a
resin specimen dried to 0.1% or below in moisture. At an elapse of
one minute after the filling, a load (98N) was applied on the
specimen by means of a plunger, whereby the melted specimen is
extruded from the die at the bottom of the cylinder (hole diameter:
1.0 mm; thickness: 10 mm). The dropping distance and dropping time
of the plunger were recorded to calculate the melt viscosity.
[0051] TENSILE BREAKING STRENGTH, TENSILE BREAKING ELONGATION: A
polyester sheet (width 15 mm, thickness 0.2 mm, length 50 mm) was
prepared. The tensile breaking strength and tensile breaking
elongation at 23.degree. C. and 50% RH were measured using a
tensile tester under the conditions of distance of 30 mm between
the chucks and a tensile rate of 50 mm/min.
[0052] NUMBER-AVERAGE MOLECULAR WEIGHT: Using a gel permeation
chromatography (GPC) 150c from Waters Corporation with a chloroform
as an eluate, GPC measurement was conducted at the column
temperature of 35.degree. C. and flow rate of 1 cm.sup.3/min. Based
on calculation from the results, the measured value converted in
polystyrene was obtained.
[0053] Preparation of Polyester Resin
[0054] A polyester resin (A) was obtained as set forth below. In a
reactor equipped with an agitator, a thermometer and a cooler for
distillation, 166 weight parts of terephthalic acid, 180 weight
parts of 1,4-butanediol, and 0.25 weight parts of tetrabutyl
titanate were added and subjected to esterification for 2 hours at
170-220.degree. C. After esterification is completed, 300 weight
parts of polytetramethylene glycol "PTMG1000" (product of
Mitsubishi Chemical) with a number-average molecular weight of 1000
and 0.5 weight parts of a hindered phenol based antioxidant
"Irganox1330" (Ciba-Geigy Ltd.) were introduced. The temperature
was raised up to 255.degree. C. while the interior was gradually
reduced in pressure to achieve 665 Pa at 255.degree. C. in 60
minutes. Then, a polycondensation reaction was effected for 30
minutes at 133 Pa or below. This obtained polyester resin (A) had a
melting point of 165.degree. C. and a melt viscosity of 250
dPa.multidot.s.
[0055] Polyester resins (B) to (K) were synthesized in a manner
similar to that of the above polyester resin (A). Respective
compositions and values of physical properties are shown in Table
1.
[0056] Polyester resins (A) to (H) satisfy the requirements of the
claims. Polyester resin (I), polyester resin (J), and polyester
resin (K) do not satisfy the requirements of the claims in the melt
viscosity at 200.degree. C., the product of the tensile breaking
strength and tensile breaking elongation, and the melt viscosity at
200.degree. C. as well as the product of the tensile breaking
strength and tensile breaking elongation, respectively. Polyester
resin (K) was used as the material to fabricate a polyester resin
composition that will be described afterwards.
1TABLE 1 Polyester Resin A B C D E F G H I J K Composition (mole %)
Dicarboxylic acid component TPA 100 70 70 75 100 80 75 65 50 NDCA
100 100 IPA 30 30 25 10 50 AA 25 DIA 25 DDA 20 Diol component BD 70
60 60 90 100 75 100 100 100 EG 90 50 PTG1000 30 40 10 10 PTG2000 40
DID 25 NPG 50 Resin Physical Properties Melt viscosity (dPa
.multidot. s, 200.degree. C.) 250 500 500 600 800 500 400 700 1500
300 3.5 Melting point (.degree. C.) 160 160 159 154 164 174 173 194
185 165 none (amorphous) Glass transition temperature (.degree. C.)
-65 -70 -75 -60 -50 -45 -45 -24 25 -5 55 Ester group concentration
4000 3100 1900 6400 7000 6300 5900 8600 9000 9300 9400
(equivalent/10.sup.6g) Tensile breaking strength (N/mm.sup.2) 7 4 6
10 20 6 6 20 35 15 30 *1) Tensile breaking elongation (%) 400 1000
1100 500 500 300 450 55 50 26 5 *1) Product a .times. b 2800 4000
6600 5000 10000 1800 2700 1100 1750 390 150 Number-average
molecular weight 20000 25000 35000 28000 35000 30000 27000 26000
30000 7000 2200 *1) measured using sample of 2 mm in thickness
[0057] The abbreviations in Table 1 are as follows:
[0058] TPA: Terephthalic acid; NDCA: naphthalene dicarboxylic acid;
IPA: isophthalic acid; AA: adipic acid; DIA: hydrogenated dimer
acid; DDA: dodecane dicarboxylic acid; BD: 1,4-butanediol; EG:
ethylene glycol; PTG1000: polytetramethylene glycol (number-average
molecular weight of 1000); PTG2000: polytetramethylene glycol
(number-average molecular weight of 2000); DID: hydrogenated
dimerdiol; NPG: neopentyl glycol.
[0059] Preparation of Polyester Resin Composition
[0060] A polyester resin composition (M) was prepared as set forth
below. 76 weight parts of polyester resin (A), 6 weight parts of
antimony trioxide and 18 weight parts of poly styrene dibromide as
a flame retardant were mixed uniformly, and then melted and kneaded
at a die temperature of 170.degree. C. using a two-shaft
extruder.
[0061] Polyester resin compositions (N) to (S) were prepared in a
manner similar to that of the above polyester resin composition
(M). Respective compositions and values of physical properties are
shown in Table 2.
[0062] Polyester resin compositions (M) to (Q) satisfy the
requirements of the claims. Polyester resin composition (R) does
not satisfy the requirements of the claims in the type of the
polyester resin and the product of the tensile breaking strength
and tensile breaking elongation. Polyester resin composition (S)
does not satisfy the requirements of the claims in the polyester
resin ingredient ratio and the product of the tensile breaking
strength and tensile breaking elongation.
2TABLE 2 Polyester Resin Composition M N O P Q R S Composition (wt
%) Polyester resin A 76 98.5 95 64 66 26 J 40 62 K 36 32.5 Epoxy
resin 5 Epikote 1004 *2) Flame-retardant Antimony trioxide 6 15 3
(Pyroguard *3) Poly styrene 18 45 9 dibromide (PDBS-80 *4)
Anti-oxidant ADK Stab 1.0 1.0 AO-60 *5) ADK Stab 0.5 0.5 AO-412S
*6) Resin Physical Properties Melt viscosity 400 250 220 200 200
500 270 (dPa .multidot. s, 200.degree. C.) Tensile breaking 7 7 7 6
6 9 10 strength (N/mm.sup.2) Tensile breaking 250 400 400 200 220
15 40 elongation (%) Product a .times. b 1750 2800 2800 1200 1320
135 400 *2) Yuka Shell Epoxy KK *3) Dai-Ichi Kogyo Seiyaku
Pyroguard AN-800 *4) Great Lakes Chemical Corp. *5) Asahi Denka
Kogyo <pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-
-hydroxyphenyl)propionate)> *6) Asahi Denka Kogyo
<2,2-bis[[3-(dodecylthio)-1-oxopropoxy]methyl]propane-1,3-diyl
bis[3-(dodecylthio)propionate]>
[0063] Then, ten types of the resins for molding, namely polyester
resins (A) to (J) and a dimer acid based polyamide resin were
melted at 200.degree. C., and subjected to injection molding using
an applicator "WS102/MX3006" available from Nordson Corporation for
low pressure (up to 300 N/cm.sup.2) injection molding. The material
to be molded was molded over a circuit board of 20 mm.times.15 mm
with two lead wires of polyvinyl chloride in an aluminum die having
an inside dimension of 25 mm.times.20 mm.times.50 mm. The period of
time of release from the die without any defect in the shape of the
formed product (mold release time) and the formed state
corresponding to the circuit board were observed. The circuit board
was left for 100 hours at 80.degree. C..times.95% RH. The retention
of the circuit resistance was measured. A higher retention
indicates its higher suitability for the insulation material of an
electrical electronic component. Also, each resin sample was
subjected to a pressure cooker test (121.degree. C., 0.2 MPa, 100
hours), and the retention of melt viscosity was obtained. The
hydrolyzable resistance of the polyester resin became lower in
proportion to a lower retention, having the tendency of degradation
in the durability over a long period of time. Furthermore, the
appearance of the formed product after a heat cycle test (twenty
times from -40.degree. C. to 80.degree. C. was observed). The
results are shown in Table 3.
[0064] The retention of the melt viscosity before and after the
heat treatment test was obtained as set forth below. A sample of 1
cm.times.1 cm.times.1 cm was cut out and processed by a pressure
cooker tester TTC-411 Type available from TABAI ESPEC Corporation.
The retention was obtained comparing the melt viscosity before and
after the heat treatment test. Measurement of the melt viscosity
was carried out as described above.
3 TABLE 3 Mold release Forming Appearance of Retention of Retention
of Appearance after Mold Material time (second) workability formed
product circuit resistance melt viscosity heat cycle Example 1
Polyester resin A 3 good good 98% 99% good Example 2 Polyester
resin B 7 good good 98% 99% good Example 3 Polyester resin C 10
good good 98% 100% good Example 4 Polyester resin D 5 good good 98%
98% good Example 5 Polyester resin E 15 good good 98% 97% good
Example 6 Polyester resin F 10 good good 95% 98% good Example 7
Polyester resin G 10 good good 99% 98% good Example 8 Polyester
resin H 3 good good 72% 75% small crack Comparative Polyester resin
I 4 nozzle defect in 99% 65% crack Example 1 clogging in formed
product forming line Comparative Polyester resin J 5 good crack
after 0% 20% crack Example 2 cooling Comparative Polyamide resin 15
good good 10% 98% coloring Example 3 (black)
[0065] A formed product was produced in a manner as described above
for each of polyester resin compositions (M) to (S). The mold
release time, forming workability, appearance of the formed
product, retention of the circuit resistance, retention of the melt
viscosity, and the appearance after the heat cycle were observed.
The results are shown in Table 4.
4 TABLE 4 Mold release Forming Appearance of Retention of Retention
of Appearance after Mold Material time (second) workability formed
product circuit resistance melt viscosity heat cycle Example 9
Polyester resin M 4 good good 98% 99% good Example 10 Polyester
resin N 3 good good 99% 100% good Example 11 Polyester resin O 5
good good 99% 100% good Example 12 Polyester resin P 8 good good
97% 97% good Example 13 Polyester resin Q 8 good good 98% 99% good
Comparative Polyester resin R 4 good crack after 0% 10% crack
Example 4 cooling Comparative Polyester resin S 4 good good 0% 10%
crack Example 5
[0066] It is appreciated from Tables 1 and 3 that the properties of
the formed products using polyester resins (A) to (H) satisfying
the requirements of the claims were all favorable. However, the
characteristics of the formed products using polyester resins (I)
and (J) and a polyamide resin that do not satisfy the requirements
of the claims exhibited great degradation.
[0067] Furthermore, it is appreciated from Tables 2 and 4 that the
properties of formed products using polyester resin compositions
(M) to (Q) satisfying the requirements of the claims were all
favorable. However, the properties of formed products using
polyester resin compositions (R) and (S) that do not satisfy the
requirements of the claims exhibited considerable degradation.
[0068] Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example only and is not to be taken by way
of limitation, the spirit and scope of the present invention being
limited only by the terms of the appended claims.
* * * * *