U.S. patent application number 10/124463 was filed with the patent office on 2003-03-06 for hydraulic or pneumatic device comprising tube comprising polyamide resin.
This patent application is currently assigned to UBE Industries, Ltd.. Invention is credited to Iwata, Yoshiro, Matsuda, Shinya.
Application Number | 20030045639 10/124463 |
Document ID | / |
Family ID | 18969390 |
Filed Date | 2003-03-06 |
United States Patent
Application |
20030045639 |
Kind Code |
A1 |
Iwata, Yoshiro ; et
al. |
March 6, 2003 |
Hydraulic or pneumatic device comprising tube comprising polyamide
resin
Abstract
A hydraulic or pneumatic device is described, which comprises a
tube comprising a polyamide resin composition comprising (A) from
70 to 97% by weight, based on the weight of the polyamide resin
composition, of a polyamide resin and (B) from 3 to 30% by weight,
based on the weight of the polyamide resin composition, of a
plasticizer comprising an ester of p- and/or o-hydroxybenzoic acid
with a C.sub.12-C.sub.22 aliphatic alcohol having a branched chain
and a component comprising a rubber compound comprising a polar
rubber as a main component, and which exhibits a high reliability
over an extended period of time.
Inventors: |
Iwata, Yoshiro; (Yamaguchi,
JP) ; Matsuda, Shinya; (Yamaguchi, JP) |
Correspondence
Address: |
AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.
Suite 2200
One Commerce Square
2005 Market Street
Philadelphia
PA
19103
US
|
Assignee: |
UBE Industries, Ltd.
|
Family ID: |
18969390 |
Appl. No.: |
10/124463 |
Filed: |
April 17, 2002 |
Current U.S.
Class: |
525/178 ;
428/36.9 |
Current CPC
Class: |
C08L 9/00 20130101; C08L
77/06 20130101; Y10T 428/1352 20150115; C08L 77/02 20130101; C08K
5/1345 20130101; F16L 2011/047 20130101; C08L 77/06 20130101; Y10T
428/139 20150115; C08L 77/00 20130101; F16L 11/125 20130101; C08K
5/1345 20130101; C08L 2666/08 20130101; C08L 77/00 20130101; C08L
77/02 20130101; C08L 2666/08 20130101; C08L 77/00 20130101; C08L
2666/08 20130101 |
Class at
Publication: |
525/178 ;
428/36.9 |
International
Class: |
F16L 001/00; C08L
077/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2001 |
JP |
P.2001-119122 |
Claims
What is claimed is:
1. A hydraulic or pneumatic device comprising: a tube comprising a
polyamide resin composition comprising: (A) from 70 to 97% by
weight, based on the weight of the polyamide resin composition, of
a polyamide resin and (B) from 3 to 30% by weight, based on the
weight of the polyamide resin composition, of a plasticizer
comprising an ester of at least one of p-hydroxybenzoic acid and
o-hydroxybenzoic acid with a C.sub.12-C.sub.22 aliphatic alcohol
having a branched chain and a component comprising a rubber
compound comprising a polar rubber as a main component.
2. A hydraulic or pneumatic device comprising: a tube comprising a
polyamide resin composition comprising: (A) from 50 to 96% by
weight, based on the weight of the polyamide resin composition, of
a polyamide resin, (B) from 3 to 30% by weight, based on the weight
of the polyamide resin composition, of a plasticizer comprising an
ester of at least one of p-hydroxybenzoic acid and o-hydroxybenzoic
acid with a C.sub.12-C.sub.22 aliphatic alcohol having a branched
chain and (C) from 1 to 20% by weight, based on the weight of the
polyamide resin composition, of an impact-resistant material and a
component comprising a rubber compound comprising a polar rubber as
a main component.
3. The hydraulic or pneumatic device according to claim 1, wherein
said polyamide resin is polyamide 6, polyamide 11, polyamide 12,
polyamide 66, polyamide 610, polyamide 612 or copolymer
thereof.
4. The hydraulic or pneumatic device according to claim 2, wherein
said polyamide resin is polyamide 6, polyamide 11, polyamide 12,
polyamide 66, polyamide 610, polyamide 612 or copolymer
thereof.
5. The hydraulic or pneumatic device according to claim 1, wherein
said polar rubber comprises NBR as a main component.
6. The hydraulic or pneumatic device according to claim 2, wherein
said polar rubber comprises NBR as a main component.
7. The hydraulic or pneumatic device according to claim 1, wherein
said component comprising a rubber compound comprises a clamping
part used as a sealing material at least at one point.
8. The hydraulic or pneumatic device according to claim 2, wherein
said component comprising a rubber compound comprises a clamping
part used as a sealing material at least at one point.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a hydraulic or pneumatic
device which exhibits a high reliability over an extended period of
time.
BACKGROUND OF THE INVENTION
[0002] The hydraulic tube for power transmission for general
industrial use and the pneumatic tube for automobile air brake have
heretofore been made of a material such as metal, rubber and resin.
However, a tube made of a resin having a lighter weight and a good
workability (mountability) has recently been used more and
more.
[0003] As the material of resin tube there has been widely used a
plasticized flexible material such as nylon 6, nylon 11, nylon 12
and copolymer comprising these nylons as main components from the
standpoint of low temperature impact resistance, stress cracking
resistance by metal chloride and flexibility.
[0004] A handbook of nylon resins describes that nylon 11 and nylon
12 comprise a higher alcohol, hydroxybenzoic acid ester, aromatic
sulfonamide, etc. incorporated therein as a plasticizer. Among
these nylons, nylons plasticized with an aromatic sulfonamide are
normally used.
[0005] However, a pneumatic or hydraulic tube made of such an
ordinary commercial flexible nylon plasticized by an aromatic
sulfonamide-based plasticizer can have an impaired airtightness
after a prolonged use. This is because when the tube is exposed to
a relatively high temperature, the plasticizer bleeds out to reduce
the thickness of the tube, giving an adverse effect, or when an
O-ring or the like mainly composed of a polar rubber, in particular
NBR, which is normally used, is used as a seal, the plasticizer
which then bleeds therefrom and is entrained by air or is extracted
with an oil is then absorbed by the sealing material to swell the
rubber, deteriorating the sealing properties thereof and hence the
airtightness of the tube.
SUMMARY OF THE INVENTION
[0006] An object of the invention is to provide a hydraulic or
pneumatic device which exhibits a high reliability over an extended
period of time.
[0007] In the invention, it was found that the combined use of a
tube comprising a polyamide resin composition comprising (A) a
polyamide resin and (B) a plasticizer comprising a specific benzoic
acid ester and a component comprising a rubber compound comprising
a polar rubber as a main component can provide a hydraulic or
pneumatic device with a remarkable improvement in long-term
reliability such as airtightness.
[0008] In other words, the invention relates to a hydraulic or
pneumatic device comprising a tube comprising a polyamide resin
composition comprising (A) from 70 to 97% by weight, based on the
weight of the polyamide resin composition, of a polyamide resin and
(B) from 3 to 30% by weight, based on the weight of the polyamide
resin composition, of a plasticizer comprising an ester of at least
one of p-hydroxybenzoic acid and o-hydroxybenzoic acid with a
C.sub.12-C.sub.22 aliphatic alcohol having a branched chain and a
component comprising a rubber compound comprising a polar rubber as
a main component.
[0009] The invention also relates to a hydraulic or pneumatic
device comprising a tube comprising a polyamide resin composition
comprising (A) from 50 to 96% by weight, based on the weight of the
polyamide resin composition, of a polyamide resin, (B) from 3 to
30% by weight, based on the weight of the polyamide resin
composition, of a plasticizer comprising an ester of at least one
of p-hydroxybenzoic acid and o-hydroxybenzoic acid with a
C.sub.12-C.sub.22 aliphatic alcohol having a branched chain and (C)
from 1 to 20% by weight, based on the weight of the polyamide resin
composition, of an impact-resistant material and a component
comprising a rubber compound comprising a polar rubber as a main
component.
DETAILED DESCRIPTION OF THE INVENTION
[0010] The invention will be further described hereinafter.
[0011] The polyamide resin (A) to be used in the invention is made
from a diamine and a dibasic acid or made from a lactam or an
aminocarboxylic acid or is a copolymer of two or more of these
components.
[0012] Examples of the diamine include aliphatic diamines such as
tetramethylenediamine, hexamethylenediamine, octamethylenediamine,
nonamethylenediamine, undecamethylene diamine and
dodecamethylenediamine, and diamines having aromatic cyclic
structure such as methaxylylenediamine.
[0013] Examples of the dicarboxylic acid include aliphatic diamines
such as adipic acid, heptanedicarboxylic acid, octanedicarboxylic
acid, nonanedicarboxylic acid, undecanedicarboxylic acid and
dodecanedicarboxylic acid, and dicarboxylic acids having aromatic
cyclic structure such as terephthalic acid and isophthalic
acid.
[0014] The lactam is a C.sub.6-C.sub.12 lactam. The aminocarboxylic
acid is a C.sub.6-C.sub.12 aminocarboxylic acid. Examples of the
C.sub.6-C.sub.12 lactam or the C.sub.6-C.sub.12 aminocarboxylic
acid include 6-aminocaproic acid, 7-aminoheptanoic acid,
11-aminoundecanoic acid, 12-aminododecanoic acid,
.alpha.-pyrrolidone, .epsilon.-caprolactam, .omega.-laurolactam,
and .epsilon.-enantholactam.
[0015] The tube is preferably made of a material having a wide
working temperature range, a high thermal stability and an
excellent extrudability. As such a material there is preferably
used a homopolymer having a relatively low melting point such as
polyamide 6, polyamide 11, polyamide 12, polyamide 610 and
polyamide 612 or a copolymer such as polyamide 6/66, polyamide 6/12
and polyamide 11/12.
[0016] The component (A) to be used in the invention may be a
mixture with the other polyamide resin or other polymer. The
content of the polyamide resin in the mixture is preferably not
lower than 50% by weight based on the weight of the mixture.
[0017] Examples of the polyamide resin to be incorporated in the
mixture include polyamide 6, polyamide 66, polyamide 11, polyamide
12, polyamide 912, polyamide 1010, polyamide 610, polyamide 612,
polyamide 1212, polyamide 6/66 copolymer, polyamide 11/12
copolymer, and polyamide 6/12 copolymer. Examples of the other
polymer include polypropylene, ABS resin, polyphenylene oxide,
polycarbonate, polyethylene terephthalate, and polybutylene
terephthalate.
[0018] The polyamide resin to be used as the component (A) in the
invention may comprise a function-providing agent such as
heat-resisting agent, weathering agent, crystal nucleating agent,
crystallization accelerator, release agent, lubricant, antistatic
agent, flame retardant, auxiliary flame retardant and colorant
incorporated therein.
[0019] Specific examples of the heat-resisting agent include
hindered phenols, phosphites, thioethers, and copper halide. These
compounds may be used singly or in combination.
[0020] Examples of the weathering agent include hindered amines,
and salicylates. These compounds may be used singly or in
combination.
[0021] Examples of the crystal nucleating agent include inorganic
fillers such as talc and clay, and organic crystal nucleating
agents such as fatty acid metal salt. These compounds may be used
singly or in combination.
[0022] Examples of the crystallization accelerator include low
molecular polyamides, higher fatty acids, higher fatty acid esters,
and higher aliphatic alcohols. These compounds may be used singly
or in combination.
[0023] Examples of the release agent include fatty acid metal
salts, fatty acid amides, and various waxes. These compounds may be
used singly or in combination.
[0024] Examples of the antistatic agent include aliphatic alcohols,
aliphatic alcohol esters, and higher fatty acid esters. These
compounds may be used singly or in combination.
[0025] Examples of the flame retardant include metal hydroxides
such as magnesium hydroxide, phosphorus, ammonium phosphate,
ammonium polyphosphate, melamine cyanurate, ethylenedimelamine
dicyanurate, potassium nitrate, brominated epoxy compound, bromated
polycarbonate compound, brominated polystyrene compound,
tetrabromobenzyl polyacrylate, tribromophenol polycondensate,
polybromobiphenyl ethers, and chlorine-based flame retardants.
These compounds may be used singly or in combination.
[0026] The plasticizer (B) to be used in the invention is made from
an ester of p-hydroxybenzoic acid and/or o-hydroxybenzoic acid with
a C.sub.12-C.sub.22 aliphatic alcohol having a branched chain. The
alcohol from which the ester is produced needs to have branched
chains and from 12 to 22 carbon atoms. Any saturated or unsaturated
alcohols may be used so far as they satisfy these requirements.
[0027] An ester of such an alcohol with hydroxybenzoic acid
exhibits a good compatibility with the polyamide resin, renders the
surface of the resin little sticky, has a low volatility and exerts
a sufficient plasticizing effect.
[0028] On the contrary, an ester comprising an alcohol having 11 or
less carbon atoms as a starting material is disadvantageous in that
it has a high volatility. An ester comprising an alcohol having 23
or more carbon atoms as a starting material has a low volatility
but exerts an insufficient plasticizing effect.
[0029] Further, an ester comprising an alcohol free of branched
chain as a starting material cannot attain both low volatility and
plasticizing effect.
[0030] As the alcohol from which the ester is produced there may be
used 2-octyl octanol, 2-octyldodecyl alcohol, 2-hexyl decanol,
2-decyl decanol, 2-decyldodecyl alcohol, 2-ethyldodecyl alcohol,
2-octyl-3-octenol or the like.
[0031] The amount of the plasticizer to be incorporated is from 3
to 30% by weight, preferably from 5 to 15% by weight, based on 100%
by weight of the polyamide resin composition. When the amount of
the plasticizer to be incorporated exceeds 30% by weight, the
resulting tube exhibits a lowered burst pressure and undergoes
bleedout to disadvantage.
[0032] Examples of the impact-resistant material (C) to be used in
the invention include ionomer, ethylene-.alpha.-olefin copolymer,
ethylene-.alpha.-olefin terpolymer,
polystyrene-polyethylene-butylene block copolymer,
polystyrene-hydrogenated polyisoprene block copolymer, rubber such
as ethylene octene rubber, elastomer, modification product thereof,
mixture thereof or the like.
[0033] The amount of the impact-resistant material to be
incorporated is from 1 to 20% by weight, preferably from 2 to 10%
by weight, based on 100% by weight of the polyamide resin
composition. When the amount of the impact-resistant material to be
incorporated exceeds 20% by weight, the resulting tube exhibits a
lowered burst pressure and has a weathering problem to
disadvantage.
[0034] On the other hand, examples of the polar rubber to be used
in the invention include NBR (acrylonitrile-butadiene rubber), CHR
(halobutyl rubber), CSM (chlorosulfonated polyethylene), CLPE
(chlorinated polyethylene), urethane, and fluoro rubber.
[0035] A hydraulic or pneumatic device is much likely to come in
contact with a nonpolar oil such as mineral oil and thus preferably
comprises a polar rubber, in particular an NBR-based rubber as a
component from the standpoint of oil resistance and price.
[0036] Further, these polar rubbers may be used in the form of
mixture with other polar or nonpolar rubbers or a flexible resin
such as PVC (polyvinyl chloride). Moreover, the polar rubber of the
invention may comprise additives which are normally incorporated in
rubbers. Examples of the additives employable herein include
vulcanizing agent, vulcanization accelerator, vulcanization
promoter, scorch retarder, antioxidant, peptizer, tackfier, rubber
softener, reinforcing agent/filler, flame retardant, colorant, and
foaming agent.
[0037] The polyamide resin composition of the invention is formed
into a tube form which is then used as hydraulic/pneumatic line. As
necessary, a multi-layer tube comprising at least one layer of
polyamide resin composition tube of the invention, too, may be used
in the hydraulic or pneumatic device of the invention. Further, a
hose having a high pressure resistance obtained by intertwining a
reinforcing yarn or the like on the periphery of the polyamide
resin composition tube of the invention, and then further covering
the tube by an elastomer or rubber may be used in the hydraulic or
pneumatic device of the invention. The composition of the invention
has an adaptability as a polyamide material for automobile and thus
can be used also for automobile air brake. For parts which need to
expand and contract, the composition of the invention may be used
as a coil tube formed by coiling the composition.
[0038] Referring to the process for the production of the tube of
the invention, a molten resin which has been extruded from an
extruder can be extruded through a die into a cylindrical form
which is then solidified by cooling sizing to obtain a desired
tubular product.
[0039] Examples of the process for the production of a multi-layer
tube include a process which comprises introducing a molten resin
extruded from extruders in a number corresponding to the number of
layers constituting the tube or the number of materials used into
one die for multi-layer tube, allowing various layers to be bonded
to each other while being inside the die or shortly after being
extruded from the die, and then processing the material in the same
manner as in ordinary tube forming, and a process which comprises
forming a single-layer tube, and then coating the tube with other
layers.
[0040] Further, a pressure-resistant hose can be obtained by a
process which comprises extruding a molten resin onto a mandrel so
that it is coated, subjecting the material to braiding, knitting,
spiral, wrapping; insert, etc. to form a reinforcing layer thereon,
coating the material with an elastomer or rubber, and then
subjecting the material to crosslinking.
[0041] The polar rubber composition of the invention can be worked
into an oil seal, O-ring or the like which is then used as a
component of hydraulic or pneumatic device.
[0042] In the hydraulic or pneumatic device of the invention, the
component formed by a polar rubber compound contains a clamping
part used as a sealing material at least at one point.
[0043] Examples of other constituents of the hydraulic or pneumatic
device of the invention include those which are normally
incorporated in hydraulic or pneumatic devices such as pump,
connector, controller, valve and cylinder.
[0044] Specific examples of the hydraulic or pneumatic device of
the invention include pneumatic brake, hydraulic brake, door
switch, locking device, air suspension device, hydraulic steering,
trailer brake, hoist controller, industrial machine hydraulic
device, and lubricant supplier.
[0045] The reason why the hydraulic or pneumatic device comprising
a polyamide resin composition tube of the invention and a polar
rubber component has a high long-term reliability is presumed as
follows.
[0046] The polyamide resin composition of the invention comprises a
plasticizer which can difficultly undergo bleeding (volatilization)
or extraction as compared with the conventional benzenesulfonic
acid-based plasticizer and thus has an enhanced dimensional
stability that stabilizes the clamping portion or reduces the
movement toward the rubber layer, giving little absolute effect.
The plasticizer to be incorporated in the polyamide resin
composition has a lower polarity (SP value) than the conventional
benzenesulfonic acid-based plasticizer. The resulting polar rubber
has a low swelling. The term "SP value" as used herein means a
solubility parameter. The solubility parameter has been defined as
the square root of the cohesive energy density and describes the
attractive strength between molecules of the material. (see Polymer
Handbook VII, pp. 519-557) The closer the SP values of molecules,
the higher the compatibility thereof.
[0047] Further, the combined use of a tube made of a plastic nylon
resin composition having both a relatively excellent pressure
resistance and a high flexibility giving a good handleability and a
rubber component gives a degree of freedom at which various
requirements can be met by various combinations of resin tube and
rubber component and thus has a high value of industrial
utilization.
[0048] The invention will be explained below in more detail by
reference to the following Examples and Comparative Examples, but
the invention should not be construed as being limited thereto.
[0049] The measurement of physical properties in the Examples and
Comparative Examples were conducted as follows.
[0050] Tube Properties
[0051] The tube was subjected to burst pressure (and hoop stress)
and low temperature impact tests in accordance with the method
defined in DIN73378. For the evaluation of the low temperature
impact strength, the tube which had been cooled to a temperature of
-40.degree. C. was given an impact by a hammer in a Charpy impact
tester, and then observed for break.
[0052] Dimensional Stability
[0053] A test piece having a size of 30 mm.times.100 mm.times.3 mm
thick was formed. The test piece thus formed was treated in a
100.degree. C. oven with internal air circulation for 72 hours, and
then evaluated for change of dimension and weight. The test piece
was also dipped in a 100.degree. C. JIS 3 oil for 72 hours, and
then similarly evaluated for change of dimension and weight. For
the determination of change of dimension, longitudinal and
crosswise changes were averaged.
[0054] Test of Dipping of O-Ring in Plasticizer
[0055] In order to evaluate the effect of the plasticizer bled or
evaporated from the tube on an O-ring in the form of mixture with a
lubricant, the O-ring was measured for change after dipped in a
mixture of the lubricant and the plasticizer. As the lubricant
there was used DEXRON III. The concentration of the plasticizer was
from 0% to 10% by volume based on the total volume of the lublicant
and the plasticizer. The dipping temperature was 100.degree. C.
After a predetermined period of time of dipping, the O-ring was
withdrawn from the mixture, and then evaluated by the measurement
of weight and outermost diameter and by tensile test. In order to
determine the reference value of weight and dimension of outermost
diameter of the O-ring, the values of 10 undipped samples were
averaged.
EXAMPLE 1
[0056] A polyamide resin composition containing 90% by weight,
based on the weight of the polyamide resin composition, of
polyamide 12 (UBESTA3030U, produced by Ube Industries, Ltd.) and
10% by weight, based on the weight of the polyamide resin
composition, of p-hydroxybenzoic acid-2-hexyldecylester
(hereinafter referred to as "benzoic acid ester plasticizer A") was
melt-kneaded through a twin-screw extruder to form pellets which
were then processed in a 70.degree. C. vacuum dryer for 48 hours to
prepare a sample.
EXAMPLE 2
[0057] A polyamide resin composition containing 85% by weight,
based on the weight of the polyamide resin composition, of
polyamide 12 (UBESTA3030U, produced by Ube Industries, Ltd.), 5% by
weight, based on the weight of the polyamide resin composition, of
a modified EPR (T7712SP, produced by JSR) and 10% by weight, based
on the weight of the polyamide resin composition, of
p-hydroxybenzoic acid-2-hexyldecylester (hereinafter referred to as
"benzoic acid ester plasticizer A") was melt-kneaded through a
twin-screw extruder to form pellets which were then processed in a
70.degree. C. vacuum dryer for 48 hours to prepare a sample.
COMPARATIVE EXAMPLE 1
[0058] A polyamide resin composition containing 90% by weight,
based on the weight of the polyamide resin composition, of
polyamide 12 (UBESTA3030U, produced by Ube Industries, Ltd.) and
10% by weight, based on the weight of the polyamide resin
composition, of benzenesulfonbutylamide (hereinafter referred to as
"benzenesulfonic acid plasticizer A") was melt-kneaded through a
twin-screw extruder to form pellets which were then processed in a
70.degree. C. vacuum dryer for 48 hours to prepare a sample.
COMPARATIVE EXAMPLE 2
[0059] A polyamide resin composition containing 85% by weight,
based on the weight of the polyamide resin composition, of
polyamide 12 (UBESTA3030U, produced by Ube Industries, Ltd.), 5% by
weight, based on the weight of the polyamide resin composition, of
a modified EPR (T7712SP, produced by JSR) and 10% by weight, based
on the weight of the polyamide resin composition, of
benzenesulfonbutylamide (hereinafter referred to as
"benzenesulfonic acid plasticizer A") was melt-kneaded through a
twin-screw extruder to form pellets which were then processed in a
70.degree. C. vacuum dryer for 48 hours to prepare a sample.
[0060] These pelletized samples were each plasticized by a
full-flighted screw extruder to give a molten resin which was then
extruded from a die through a head adapter to form a cylinder. The
cylinder was then solidified by a sizing die in a vacuum cooling
water bath. The cylinder thus solidified was then withdrawn by a
pulling device to form a tube. Using this device, a tube having an
outer diameter of 12 mm and a thickness of 1.5 mm was prepared.
[0061] The tube thus formed was then evaluated for burst pressure
(hoop stress) and low temperature impact resistance each according
to DIN73378. The results are set forth in Table 2.
[0062] These pelletized samples were each subjected to injection
molding. The molten resin was injected through a film gate to form
a test piece having a size of 30 mm (transverse
direction).times.100 mm (machine direction).times.3 mm (thickness)
which was then evaluated for change of dimension and weight at
100.degree. C.
1 TABLE 1 Plasticizer Impact- Polyamide Benzene- resistant resin
Benzoic sulfonic material Polyamide acid ester acid Modified 12
plasticizer plasticizer EPR % by A A % by weight % by weight % by
weight weight Example 1 90 10 Example 2 85 10 5 Comparative 90 10
Example 1 Comparative 85 10 5 Example 2
[0063]
2 TABLE 2 Low temperature impact resistance Burst Hoop Number of
units pressure stress broken/number of units MPa MPa tested Example
1 6.9 24.2 2/10 Example 2 6.4 22.5 0/10 Comparative 6.6 23.1 1/10
Example 1 Comparative 6.3 22.1 0/10 Example 2
[0064]
3 TABLE 3 100.degree. C. JIS 3 oil 100.degree. C. heat treatment
treatment Change of Change of Change of Change of dimension weight
dimension weight Example 1 -0.8% -1.0% -0.5% -0.2% Example 2 -0.6%
-0.9% -0.1% -0.1% Comparative -2.9% -5.1% -2.5% -6.1% Example 1
Comparative -2.6% -4.8% -1.8% -5.5% Example 2
EXAMPLE 3
[0065] An 0-ring made of NBR was dipped in an automatic oil (DEXRON
III) having 5% by volume, based on the total volume of the
automatic oil and benzoic acid ester A, of benzoic acid ester A
added thereto at a temperature of 100.degree. C. for 1,000 hours.
The O-ring was then evaluated for change of dimension, change of
weight, tensile strength at break when hooked and elongation at
break. The results are set forth in Table 4.
EXAMPLE 4
[0066] The test procedure of Example 3 was followed except that an
automatic oil having 10% by volume of benzoic acid ester A added
thereto was used. The results are set forth in Table 4.
COMPARATIVE EXAMPLE 3
[0067] The test procedure of Example 3 was followed except that an
automatic oil having 5% by volume of benzenesulfonic acid ester A
added thereto was used. The results are set forth in Table 4.
COMPARATIVE EXAMPLE 4
[0068] The test procedure of Example 3 was followed except that an
automatic oil having 10% by volume of benzenesulfonic acid ester A
added thereto was used. The results are set forth in Table 4.
COMPARATIVE EXAMPLE 5
[0069] The test procedure of Example 3 was followed except that
only an automatic oil was used. The results are set forth in Table
4.
4 TABLE 4 Treating conditions Concen- Physical properties tration
of Dimen- Elonga- plasti- sional Weight Strength tion at Plasti-
cizer increase.sup.*1 increase.sup.*1 at break break.sup.*2 cizer
(vol %) Time (hr) (%) (%) (N) (mm) Untreated Untreated Untreated --
-- 272 109 Comparative None 0 260 0 -1 279 105 Example 5 500 0 -2
242 72 1,000 0 -2 225 46 Example 3 Benzoic 5 260 2 7 278 117 acid
ester 500 3 6 271 111 plasti- 1,000 4 7 222 71 cizer A Example 4
Benzoic 10 260 6 15 271 119 acid ester 500 6 16 231 113 plasti-
1,000 5 17 204 94 cizer A Comparative Benzene- 5 260 6 20 235 112
Example 3 sulfonic 500 6 16 175 96 acid 1,000 5 13 161 61 plasti-
cizer A Comparative Benzene- 10 260 31 145 52 74 Example 4 sulfonic
500 38 172 36 94 acid 1,000 39 177 12 147 plasti- cizer A
.sup.*1The values of 10 untreated samples were averaged to
determine the reference value. .sup.*2Elongation of the entire
sample when loaded
[0070] The hydraulic or pneumatic device of the invention can be
used as a hydraulic or pneumatic device with a high reliability
over an extended period of time because the tube made of polyamide
resin composition incorporated therein has an excellent dimensional
stability, is not subject to troubles such as thickness reduction
and gives extremely little effect on rubber mainly composed of
butadiene, in particular NBR, for use in sealing.
[0071] The hydraulic or pneumatic device of the invention has
mechanical properties good enough for automobile use and thus has
an excellent total performance.
[0072] While the invention has been described in detail and with
reference to specific embodiments thereof, it will be apparent to
one skilled in the art that various changes and modifications can
be made therein without departing from the spirit and scope
thereof.
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