CA1296474C - Vibration dampers - Google Patents

Abstract

ABSTRACT
A first vibration damper of the present invention is obtained by reacting (a) an epoxy resin comprising polyglycidyl ether of polyol or its polymer with (b) a curing agent followed by curing. Because of its specific characteristics, the first vibration damper has excellent vibration damping capacity and is excellent in mechanical strength, service durability and moldability and, moreover, is excellent in stability even when used under the circumstances of high temperature or high vacuum.
Furthermore, a second vibration damper of the invention is obtained by reacting (a) an epoxy resin as mentioned above with (b) a curing agent in the presence of (c) a compound having a softening point of less than 25°C followed by curing. The compound (c) is a polymer containing as a principal component aromatic hydrocarbons, phenols or polymers comprising at least one member selected from among them. This second vibration damper of the invention has excellent vibration damping capacity and is excellent in mechanical strength, service durability and moldability.

Description

TITLE
VIBRATION DAMPERS

FIELD OF THE I NVENTION
This invention relates to epoxy resin based vibration dampers and more particularly to vibration dampers excellent in vibration damping capacity as well as in mechanical strength.

BACKGROUND OF THE INV~NTION
In order that vibration from a source of vibration will not be transfe~red to other portions, it has been widely practiced to allow an antivibration rubber or air spring to stand at the contacting surface between the source of vibration and other portions. In these procedures, however, no attenuation of the vibration ~; itself of the source of vibration can be expected, even though the transfer of the vibration can be inhlbited.
: ~ ~
On that account, there has been adopted a procedure wherein a vibration damper is allowed to adhere to a vibrating body so as to attenuate the vibration itself of the vibrating body. In the case of using such a vibration damper, attenuation o$ the vibration is aimed at by converting vibrational energy into heat.
~ In inhibiting vibration of a vibrating body using ': ~: ~ :
:

1296f.~. 4 a vibration damper, when amplitudes of adjacent vibrations in an attenuation sine wave are taken as X1 and X2, respectively, there is obtained an excellent vibration inhibitory effect if a logarithmic decrement represented by the following equation (1) becomes larger.

~S = ln(Xl/X2) ...(1) The logarithmic decrement ~ itself is represented by the following equation (2), using dissipation factor 7.

~ = ni~ --(2) Accordingly, it can be said that a vibration damper having a larger dissipation factor ~ has excellent characteristics.
In using such a vibration da~per in practice, there are a case wherein the vibration damper is used by simply pasting it on a source of vibration (non-constraint type) and a case wherein the vibration da~per is used by inserting it between a~source of vibration and a constraint plate (constraint type).
In the constraint type vibration damper wh.ich is used by inserting it between the vibrating body and the constraint plate, a dissipation factor~is represented ~364~4 approximately by the following equation (3).
E3 h3 ~ h31 E1 h3 ~ h1 /
~2 (3) 1 + 2g + ( 1+ 2 )g2 wherein El is Young's modulus of the vibrating body and E3 is Young's modulus of the constraint plate, hl is a thickness of the vibrating body and h3 is a thickness of the constraint plate, h3l is equal to h2 ~ (hl ~ h3)/2, h2 is a thickness of the vibration damper, 2 is dissipation factor of the vibration damper itself, g is a share parameter represented by the followiny equations (4) and (5).

f ... (4) G2 h1 / El fs 1 ... (5) 47jE3h3h2 ~ 3p 1 wherein G2 is a modulus of rigidity of the vibration damper and p1 is a density of t.he vibrating body.

It is understood from the above-mentioned iZ96~s74 ` `

equations that preferable as the vibration dampers are those having a large dissipation factor ~2 and a small modulus of rigidity.
The vibration dampers are required to have excellent moldability, mechanical strength, water resistance and chemical resistance in addition to the above-mentioned vibration damping capacity and, moreover, to be usable even under the circumstances of high temperature and high vacuum.
As vibration damping compositions used for forming such vibration dampers as mentioned above, there have heretofore been used polyamide type resins, polyvinyl chloride type resins or resins consisting essentially of epoxy resins.
However, vibration dampers formed from the vibration damping compositions comprising polyamide type resins as their principal components had such problems that the conditions under which the vibration dampers are used are limited since they are poor in water resistance as well as in chemical resistance and, moreover, they are low in mechanical strength. The vibration dampin~
compositions consisting essentially of polyvinyl chloride type resins had such problems that they are difficult to be formed into vibration dampers having complicated shapes and further that the production of vibration dampers of ~29~

many species but in small quantity requires a high cost of production. Vibration dampers formed from the vibration damping compositions consisting essentially of epoxy type resins had such problems that when the vibration dampers high in mechanical strength and excellent in service durability as well as in moldability are intended to obtain, the vibration dampers obtained are found poor in vibration damping capacity and, on one hand, when the vibration dampers excellent in vibration damping capacity are intended to obtain, the vibration dampers obtained are found low in mechanical strength and poor in service durability as well as moldability.

OBJECT OF THX INVENTION
The present invention is intended to solve such problems associated with the prior art as mentioned above, and an object oP the invention is to provide vibration dampers having excellent vibration damping capacity and being excellent in mechanical strength, service durabil.ity and moldability.

SUMMARY OF TH~ INVENTION

The Pirst vibration damper of the present invention is obtained by reacting (a) an epoxy resin comprising polyglycidyl ether of polyol or its polymer i296~74 Witll (b) a curing agent followed by curing, and characterized in that said vibration damper has a maximum value of a dissipation factor ~ being at least 1.3, a tensile strength at rupture, elongation and elastic modulu~ in tensile according to JIS K~113 being 0.05-3.0 kgf/mm2, 20-300% and 0.1-6.0 kgf/mm2, respectively, a compression ~trength according to JIS R6911 being 0.5 kgf/mm , and Izod impact strength according to JIS K6911 being at least 5 kgf cm/cm or being not ruptured.
The second vibration damper of the invention is characterized in that said vibration damper is obtained by reacting (a) an epoxy resin comprising polyglycidyl ether of polyol or it~ polymer with (b) a curing agent in the presence of (c) a compound having a softening point of less than 25C followed by curing, said compound being a polymer containing as a principal component aromatic hydrocarbons, phenols or polymers comprising at least one member selected from among them.
The vibration dampers of the invention have excellent vibration damping capacity and are excellent in mechanical strength, service durability and moldability.
In particular, the first vibration dampers of the invention have excellent vibration damping capacity and, moreover, they are excellent in mechanical strength, service durability and moldability and, in addition ~Z964 4 thereto, they are free of v~latile components and stable even when used under the circumstances of high temperature or high vacuum.

DETAILED DESCRIPTION OF THE INVENTION
The vibration dampers of the present invention are illustrated below in detail.
Fig. 1 is a diagram to show the relation between phase difference ~ , dynamic storage elastic modulus E', dynamic loss elastic Modulus E" and complex elastic modulus E of vibration damper.
The first vibration damper of the present invention is obtained by reacting (a) an epoxy resin comprising polyglycidyl ether of polyol or its polymer with (b) a curing agent, and has specific physical properties as will be mentioned later.
The epoxy resin (a), as mentioned above, is a polyglycidyl ether of polyol or its polymer, and typical examples of usable polyglycidyl ethers are such compounds as enumerated below.
(a) Diglycidyl ethers of polyols having 2 to 15 carbon atoms such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,2-butylene glycol, 1,3-lZ9~4 - a -butylene glycol, 1,4-butylene glycol, di(1,4-butylene glycol), poly(1,4-butylene glycol), neopentyl glycol, 1,6-hexanediol, di~6-hydroxyhexyl)ether, 1,8-octanediol, di(8-hydroxyoctyl)ether, 1,10-decanediol, di(10-hydroxydecyl)ether, phenylethylene glycol, di~phenylethylene glycol), etc.
~ b) Glycerol triglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane diglycidyl ether, etc.
(c) Triglycidyl ether of propylene oxide adduct of trimethylolpropane, triglycidyl ether of propylene oxide adduct of pentaeryt~ritol, etc.
Usable as the curing agent (b) are amines, acid anhydrides, polyamides, dicyandiamide, etc. Examples of useful amine~ are N-aminoethyl piperazine, diethylenetriamine, triethylenetetraamine, trimethylhexamethylenediamine, isophoronediamine, metaxylylenediamine, metaphenylenediamine, diaminodiphenylmethane, etc. Examples of useful acid anhydrides are phthalic anhydride, trimellitic anhydride, methyl tetrahydrophthalic anhydride, dodecenyl succinic anhydride, ethylene glycol bis(anhydrotrimmelitate), maleic anhydride, etc.
Such curing agent (b) as illustrated above is used in such an amount that the functional group reacting with 1296~74 the epoxy group in the curing agent becomes 0.6-1.4 equivalents, preferably 0.8-1.2 equivalents based on one equivalent of the epoxy group contained in the afQre-mentioned epoxy resin.
The first vibration damper of the invention obtained in the manner now described has a maximum value of dissipation factor ~ being at least 1.3, a tensile strength at rupture, elongation and elastic modulus in tensile according to JIS K7113 being 0.05-3.0 kgf/mm2, 20-300% and 0.1-5.0 kgf/mm2, respectively, a compression strength according to JIS K6911 being at least 0.5 kgf/mm , and Izod impact strength according to JIS K6911 being at least 5 kgf cm/cm.
The second vibration damper of the invention is obtained by reacting (a) the aforesaid epoxy resin with (b) the aforesaid curing agent in the presence of (c) a compound having a softening point of less than 25C
followed by curing, said compound (c) being a polymer containing as a principal component aromatic hydrocarbons, phenols or polymers comprising at least one member selected from among them.
The compound (c) used in the process for obtaining the second vibration damper of the invention includes such compounds as enumerated below.
(i) Aromatic hydrocarbons having a softening point of 12g~

less than 25 C, such as toluene, xylene, styrene, ~-methylstyrene, divinylbenzene, ethylbenzene, etc. or mixtures thereof.
(ii) Phenols having a softening point of less than 25C, such as cresols, vinylphenols, propylphenols, butylphenols, octylphenols, nonylphenols, dinonylphenols, dimethoxy-4-methylphenol, etc. or mixtures thereaf.
(iii) Condensates of the above-mentioned aromatic hydrocarbons, phenols of mixtures containing as a principal component at least one compound selected from among them with formaldehyde, said condensates having a softening point of less than 25C.
(iv) Polymers of the above-mentioned aromatic hydrocarbons, phenols of mixtures containing as a principal component at least compound selected from among them, said polymers having a softening point of less than The compounds ~c) as illustrated above are used in an amount of 30 - 700 parts by weight, preferably 50 500 parts by weight based on 100 parts by weight of the sum total of the epoxy resin (a) and the curing agent ~b)-In order to improve their mechanical strength, thevibration dampers of the present invention may be incorporated, if necessary, with inorganic or organic i~g6~Y4 fillers. Examples of useful inorganic fillers include mica, glass flake, scaly iron oxide, asbestos, etc., and those of useful organic fillers include synthetic pulp, polyamide flber, carbon fiber r polyester fiber, etc.
The vibration dampers of the present invention are produced by an ordinary molding process wherein a vibration damping composition is first prepared according to the usual method by thoroughly mixing the aforesaid epoxy resin (a) with the aforesaid curing agent ~b) and, according to circumstances, together with the above-mentioned compound tc) and further, optionally, together with plasticizers or fillers, and after defoaming, this vibration damping composition is cured at a temperature up to 200C to a desired form.

EFFECT OF THE INVENTION
The vibration dampers of the present invention have excellent vibration damping capacity and, moreover, they are excellent in mechanical strength, service durability and moldability. In particular, the first vibration dampers of the invention have excellent vibration damping capacity and, moreover, the~ are excellent in mechanical ~trength, service durability and moldability and, in addition thereto, they are free from volatile components and excellent in stability even when ~;~g~4 used under the circumstances of high temperature or high vacuum.
The present invention is illustrated below with reference to examples, but it should be construed that the invention is in no way limited to those examples.

~xample 1 -To lO0 g of 1,6-hexanediol diglycidyl ether having epoxy equivalent 150 g/equivalent was added 100 g of a curing agent obtained by adding 1 part by weight of 2,4,6-tris(dimethylaminomethyl)phenol to 100 parts by weight of 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, followed by thorough mixing at room temperature. There was prepared a vibration damping composition.
Thè thus obtained vibration damping composition was cured under the curing conditions of 120C x 3 hr, and a vibration damper obtained thereby was measured in the following manner for dissipation factor r~, volatile component, tensile strength at rupture, tensional elongation at rupture, elastic modulus in tension , compression strength, Izod impact strength and resistance to chipping on bending.
Methods of measurement employed are as follows:
Conditions under which dissipation factor ~ of vibration damper itself is measured) ~29~

Instrument: High-frequency viscoelasticity spectrometer, manufactured and sold by Iwamoto Seisakusho K.K.
Temperature: -50 to 200C; sample, 2 mm width x 1 mm thick x 5 mm length Frequency: 400 Hz Method of measurement and Principle: In the case where one end of a sample is fixed and the other end is intended to vibrate in the lengthwise direction o~ the sample, no measurement can be conducted in the direction toward which the sample shrinks because the sample sags.
Therefore, at the outset, the sample is stretched to a given extent, and the measurement is conducted while applying dynamic displacement centering around the stretched point of the sample. This stretch given at the outset is called an initial strain (Ls) and a tension produced when the initial strain is given is called an ~nitial tension (Fs).
When an amplitude ~Eo p) f the dynamic displacement becomes larger than the initial strain, the sample sags and the measurement comes to become inoperable, and hence thi~ should be brought to attention at the time when the mea~urement i9 conducted.
Complex elastlc modulus (Young's modulus): E*

~2964~ ~

(dyne/cm2) is calculated ac:cordin(3 to the following equation using dynamic displacement : d L _ (cm), dynamic force produced by applying the dynamic displacement to the sample: ~ Fo p (dyne), length of the sample natural length L (cm) prior to fixing the initial strain to the sample, cross-sectional area of the sample : A (cm2), phase differ-ence (Deg) between the dynamic displacement and dynamic force, and frequency of vibration ~Hz).

E* - Vibrating stress (~ Fo_p / A ) e i(~ t+~
Vibrating strain (~Lo_p / L ) e w = (aFo_p /~ Lo_p ) (L/A) ( cos~+ isin~) Assuming E = ( Fo_p / Lo p ) ( L/A) ( cos ~ + isin~), ~mic storage E = E cos ~ (dyne/cm2 ) elastic modulus D~mic loss elastic E = E sin ~ (dyne/cm2 ) modulus ~mic viscosity ~ = E / ~ (poise) coefficient Dissipation factor tan~= E / E =

= 2/~f f = frequency ( Hz ~

As can be seen from the foregoing, the initial strain and initial tension do not participate in the 1296'~4 calculation as illustrated above. The relation between E', E", E* and ~ becomes as shown in Fig. 1.
A maximum value of the dissipation factor is shown as ~ , and a temperature at which ~ is obtained is ~ max max shown by (T~)max (Method of measuring volatile component) In accordance with the procedure as stipulated in ASTM E595-77, there were obtained TML (Total Mass Loss) at 125C x 10 torr x 24 hours and CVCM (Collected Volatile Condensable Materials).
(Method of measuring tensile strength at rupture, tensile elongation at rupture and elastic modulus in tension) The measurement was conducted in accordance with JIS K~113 at a temperature of 25 + 0.2 C and a rate of pulling of 10 mm/min, using No. 2 specimen.
(Method of measuring compression strength) The measurement was conducted in accordance with JIS K69111-5.19.1 at a temperature of 25 + 0.2C and a rate of compressing of 1 mm/min.
(Method of measuring Izod impact strength) The measurement was conducted in accordance with JIS K6911-5.21 at a temperature of 25 ~ 0.2 C.
(Method of measuring resistance to chipping on bending) The resistance to chipping on bending was determined by bending a square column of the sample, 1/2 x 12~k~

1/2 x 5 inches, until the angles of both ends of the sample becomes 90 to examine occurrence of fracture.
When no fructure occurred, the tested sample was determined to come up to standard.
Vibration damping capacity of a vibration damper when it was assembled as a constraint type vibration damper to a vibrating body was measured by the following procedure. That is, a sample of the constraint type vibration damper of a sandwich structure was prepared by fitting to an aluminum vibrating plate of 300 mm length, 30 mm width and 5 mm thick a vibration damper of 3 mm thick having the same area as in the vibrating plate and an aluminum constraint plate of 2 mm thick having the same area as in the vibrating plate, and ~ of the constraint type vibration damper thus prepared was measured at a vibration frequency of 400 Hz. The maximum value of obtained was taken as ~s The results obtained are shown in Table 1.

Examples 2-7 Example 1 was repeated except that such epoxy resins as shown in Table 1 were used, respectively, in place of 1,6-hexanediol diglycidyl ether used in Example ~ The results obtained are shown in Ta~le 1.

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Example 8 Example 1 was repeated except that in place of the curing agent used in Example 1, there was used 140 g of a curing agent obtained by adding 1 part by weight of 2,4,6-tris(dimethylaminomethyl)phenol to 100 parts by weight of dodecenylsuccinic anhydride.
The results obtained are shown in Table 2.

Example 9 Example 8 was repeated except that in place of the epoxy resin used in Example 1, there were used a mixture of 50 g of dipropylene glycol diglycidyl ether and 50 g of tripropylene glycol diglycidyl ether, and the curing agent used in Rxample ~ but changing the amount thereof to 136 g~
The results obtained are shown in Table 2.

Example 10 Example 9 was repeated except that there was used the curing agent used in Example 8 but changing the amount thereof to 106 g.
The results obtained are shown in Table 2.

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4~4 Examples 11-12 The present examples illustrate the use of curing agent~ other than acid anhydrides. Example 1 was repeated except that as shown in Table 3, the kind and amount of curing agents used were changed from those of the curing agent used in Example 1, The results obtained are shown in Table 3.

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Example 13 To 100 g of 1,6-hexanediol diglycidyl ether having an epoxy equivalent 150 g/e~uivalent were added 100 g of condensate of xylene and formaldehyde (an average molecular weight 400, liquid at 25C, a viscosity 750 cps/50C) and 100 g of a curing agent obtained by adding 1 part by weight of 2,4,6-tris(dimethylaminomethyl)phenol to 100 parts by weight of 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, and the resulting mixture was thoroughly mixed to prepare a vibration damping composition.
The vibration damping composition obtained was cured under the curing conditions of 120C x 3 hr, and the vibration damper obtained was measured in the same manner as in Bxample 1 for dissipation factor ~, Izod impact strength and resistance to chipping on bending.
The results obtained are shown in Table 4.

~xamples 14-19 Example 1 wa.q repeated except that in place of the 1,6-hexanediol diglycidyl ether used in Example 13, there were used such epoxy resins as shown in Table 4 were used, respectively.
~ The results obtained are ~hown in Table 4.

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Example 20 ~ xample 15 was repeated except that in place of the curing agent used in Example 15, there was used 140 g of a curing agent obtained by adding 1 part by weight of 2,4,6-tris(dimethylaminomethyl)phenol to 100 parts by weight of dodecenylsuccinic anhydride.
The results obtained are shown in Table 5 Example 21 ~ xample 20 was repeated except that in place of the eposy resin used in Example 20, there was used a mixture of 50 g of dipropylene glycol diglycidyl ether and 50 g of tripropylene glycol diglycidyl ether, and the amount of the curing agent used was changed to 136 g.
The results obtained are shown in Table 5.

Example 22 Example 21 was repeated except that the amount of the curing agent u~ed was changed to 106 g.
The results obtained are shown in Table 5.

Examples 23-24 The present examples illustrate the use of curing agents other than acid anhydrides. ~xamples 16 was repeated except that the kind and amount of the curing ~296~4 agents used were changed as shown in Table 6.
The results obtained are shown in Table 6.

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Examples 25-29 Example 15 was repeated except that in place of the condensate of xylene and formaldehyde used as the compound (c) in Example 15, there were used other compounds, respectively, as shown in Table 7.
The results obtained are shown in Table 7.

~2~ 4 Comparative Example 1 The present example shows an instance wherein the use of the compound (c) was omitted. Example 15 was repeated except that the condensate of xylene and formaldehyde was not used.
The results obtained are shown in Table ~.

Comparative Example 2 The present example demonstrates that a vibration damper obtained by the use as the compound (c) of a compound other than those specifically defined in the present invention is found poor in vibration damping.
capacity.
~ xample 13 was repeated except that in place of the condensate of xylene and formaldehyde used in Example 13, there was used dioctyl phthalate.
The results obtained are shown in Table 8.
It is understood from this example that a vibration damper obtained in the example is rather inferior in vibration damping capacity to the vibration damper obtained in Comparative Example 1 by using no compound (c).

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Claims (7)

1. A vibration damper obtained by reacting (a) an epoxy resin comprising polyglicidyl ether of polyol or its polymer with (b) a curing agent followed by curing, characterized in that said vibration damper has a maximum value of a dissipation factor ? being at least 1.3, a tensile strength at rupture, elongation and elastic modulus in tensile according to JIS K7113 being 0.05-3.0 kgf/mm2, 20-300% and 0.1-5.0 kgf/mm2, respectively, a compression strength according to JIS K6911 being 0.5 kgf/mm2, and Izod impact strength according to JIS K6911 being at least 5 kgf cm/cm or being not ruptured.

2. The vibration damper as claimed in claim 1 wherein the epoxy resin (a) is ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether or polytetramethylene glycol glycidyl ether.

3. The vibration damper as claimed in claim 1 wherein the curing agent (b) is amines, acid anhydrides, polyamides or dicyandiamide.

4. A vibration damper, characterized in that said vibration damper is obtained by reacting (a) an epoxy resin comprising polyglycidyl ether of polyol or its polymer with (b) a curing agent in the presence of (c) a compound having a softening point of less than 25°C
followed by curing, said compound being a polymer containing as a principal component aromatic hydrocarbons, phenols or polymers comprising at least one member selected from among them.

5. The vibration damper as claimed in claim 4 wherein the epoxy resin (a) is ethylene glycol diglycidyl ether, diethylene glycol glycidyl ether, dipropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol polyglycidyl ether, diglycerol diglycidyl ether or polytetramethylene glycol diglycidyl ether.

6. The vibration damper as claimed in claim 4 wherein the curing agent (b) is amine 5, acid anhydrides, polyamides or dicyandiamide.

7. The vibration damper as claimed in claim 4 wherein the compound (c) is a condensate of xylene and formaldehyde having a softening point of less than 25°C, a polymer of isopropenyl toluene, a phenol-modified aromatic polymerized oil, a tricyclodedecene/toluene polymer or nonylphenol.