CA1308211C - Noise reduction and damping compositions - Google Patents

Abstract

TITLE
NOISE REDUCTION AND DAMPING COMPOSITIONS
ABSTRACT OF THE DISCLOSURE
A blend of a copolymer of ethylene and at least one other organic monomer X capable of being polymerized to a homopolymer having a glass transition temperature of less than about -20°C with a homopolymer or copolymer of vinyl chloride, filled with mica, which constitutes about 20-90% of the total weight of the composition, is suitable for the manufacture of noise reduction or vibration damping articles. These compositions are especially suitable for continuous use under harsh environmental conditions, for example, at high temperatures as well as at subzero °C temperatures.

Description

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TITLE
NOISE REDUCTION AND DAMPING COMPOSITIONS
BACKGROUND OF THE INVENTION
This invention relates to noise reduction and vibration damping compositions based on blends of certain ethylene pol~mers with a vinyl chloride polymer and with mica.
Noise reduction and vibration damping compositions based on various polymers or polymer blends with inorganic fillers such as, for example, barium sulfate, calcium carbonate, lead salts, and even mica are known. Especially see Japanese patent applications tKokai) 58-141230 (published August 22, 1983), 58-124923 (published August 25, 1983) both of Dainihon Ink Chemical Company, and 5~-206660 (published December ~, 1983) of Sumitomo Chemical Company, as representative of such art. They can be used in numerous applications, including automobile carpets, plant motor enclosures, building soundproofing panels, etc. Depending on their intended use, such compositions may have to meet certain special performance requirements, such as e.g., fabricability into sheets or panels and flexibility of such fabricated articles within particular temperature ranges, in addition to providing satis~actory noise reduction and vibration damping. For example, soundproofing mats for automotive use, which are placed in the engine compartment or under the hood of an automobile must be able to withstand high temperatures for prolonged periods without suffering heat-caused deterioration.
They also must be able to withstand temperatures such as may be encountered in winter in cold climate when the automobile is parked outdoors for a prolonged period. While some of the currently used commercial products provide adequate performance within reasonable temperature ranges, they are not suitable 2 ~3~8~1 for application in continuous use under harsh ~nvironmental conditions. New, improved compositions are therefore sought for such use.
SllM~RY OF THE INVENTION
According to the pre~ent invention, there is now provided a composition suitable for the manufacture of noise reduction or vibration damping articles, said composition consisting essentially of a blend of a) ab~ut 10-90% of a copolymer of ethylene with at least one organic monomer X capable of heing polymerized to a homopolymer having a glass transition temperatuxe, Tgl of less than about -20C and selected from the group consisting of es~ers of unsaturated C3-C2o mono- and dicarboxylic a~ids, vinyl esters of ! saturated C2-Cl~ carboxylic acids, and vinyl alkyl I ethers wherein the alkyl group has 1-18 carbon atoms, and an additional monomer Y 6elected from the group I consisting of ethylenically unsaturated C3-C20 carboxylic acids, carbon monoxide, and sulfur dioxide;
b) about 90-10~ of a vinyl chloride homopolymer or a copolymer of vinyl chloride with :~ another ethylenically unsaturated comonomer selected :~ from the group consisting of C2-Cs hydrocarbons, vinyl esters, acrylonitrile, acrylic esters, vinylidene chloride, esters of unsaturated carboxylic acids, and vinyl ethers;
I both percenta~es being based on the total weight of the polymers in the blend, which is about 10-~0% of the total weight of the composition; ~nd c) about 20-90% of mica, based on the total weight o~ the composition.
DETAILED DESCRIPTl:ON OF T~IE INVENTION
Generally ~peaking, the ethylene copolymer ~hould have such proportions of its comonomers that it 3 ~3~82ll can form an optically transparent blend with the vinyl chloride polymer. In such optically transparent blends, the blend polymers are compatible and form a solution in each other. The range of comonomer X thus normally will be about 1-60% of the weight of the ethylene copolymer, preferably 5-60~, and especially 5-50%. The range of comonomer Y will be within a range of about 1-30% of the weight of the ethylene pol~mer, preferably 3-30%, and especially 3-10~.
The comonomer X usually is referred to as the ~oftening comonomer. Representative ~o~tening comonomers in~lude n-butyl acrylate, sec-butyl acrylate, ethyl ~c~ylate, hexyl acrylate, pentyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-mPthoxyethyl acrylate, vinyl acetate, vinyl propionate, vinyl hexanoate, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, 2-ethylhexyl vinyl ether, and methoxyethyl vinyl ether. The preferred ~oftening comonomers are n-butyl acrylate, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate, butyl vînyl ether, and hexyl vinyl ether, but especially n-butyl acrylate.
Representative C3-C~o unsaturated carhoxylic acids that may constitute ~onomer Y which can be copolymerized with ethylene are acrylic, methacrylic, monoes~erified maleic, pre~erably methacrylic and acrylic acids.
The vinyl chloride polymer usually will be the homopolymer of vinyl chloride ~often referred to as PVC). When it i5 a copolymer o~ vinyl chloride with another comonomer, ~uitable such other comonomers include, for exampl~ ethylene, propylene, vinyl acekate, methyl acrylate, methyl methacrylate, vinyl ethyl ether, etc.

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All such monomers which can be copolymerized with ethylene to form ropolymer a) or with vinyl chloride to give polymer b) are well known and either are available commercially or can be made by known methods from readily available ~tarting material6.
Further, suitable copolymers of ethylene with comonomers X and Y and copolymers of vinyl chloride with other comonomers are known, for example, from U.S. Patent ~,613,533 to Statz et al. PVC itself is a well known commer~ial material.
The preferred amount of copolymer a) in the blend i~ 40-90%, and especially 50-75~, based on the 'T ~otal polymex content. The preferred ~mounts of I polymer b~ obviously will be complementary to 100~.
! 15 Mica, the third required component of the compositions of the present invention, i6 not a îngle chemical compound but rather a ~ember of a group of ~1 ~ilicates of varying chemical composition but having J ~imîlar physical properties and atomic ~truc~ure.
This class of compounds i~ described in various treatises of inoxganic chemîstry and is briefly defined in chemical dictionaries, such, e.g., as The Condensed Chemical Dictionary, 7th Edition, Reinhold 800k Corporation, New York, 1968. All the members of the mica family have an excellent cleavage and can be I split into very thin flexible ~heets. All contain hydroxyl, an aluminum silicate group, and an alkali~
¦ The usual varieties of mica axe muscovite, phlogopite, biotite, lepidolite, and vermiculite. Ths ch~mical formula of muscovite corresponds to 2K2.3A1203.6SiO2.2H20; that of phlogopite corresponds to ~g3Alsi3olo n In addition to mica, other inorganic filler~, such as, for example, calcium carbonate and aluminum oxide, also can be present, provided the 2~

total amount of fillers (including mica) does not exceed about 90 w~ight percent o~ the composition.
This invention is now illustrated by the following examples of certain preferred embodiments thereof, wherein all parts, proportions, and percentages are by weight unless otherwi e indicated.

Examples 1-5 ~eDaration of blended compositions Unless otherwise indicat~d, ~tabilized PVC
is a stabilized composition consisting of lO0 parts of PVC (from Conoco), 10 parts of epoxidized soybean oil 1 tParaplex [TM] G68, Rohm ~ Haas), 3 parts of a -'' barium-cadmium laurate ~tabilizer (Mark [TM] WS, lS Witco), 1 part of an alkyl aryl phosphite stabilizer (Mark [TM] 517, Witco~, 0.3 part of dilauryl thiodipropionate (DLTDP from Evans), and 0.1 part of a phenolic antioxidant (Irganox tTM] 1010 from Ciba-Geigyl-About 60 g of a ctabilized PVC was fluxed on a 76 mm roll mill at l90~C. To this was added 140 g of an ethylene/n-butyl acrylate/carbon monoxide (E/nBA/C0) 60:30:10 copolymer having a melt index of 7-10 g/10 min, as determined according to ASTM D-1238 with a weight of 2160 g. The material was milled until the blend was homogeneous and all the PVC dissolved in the copolymer. The material was removed from the mill, cooled, and cut into small porti~ns~
This polymer blend (40 g~ was again placed on the mill, and 60 g of phlogopite mica (Suzorite, Marietta Resources IntO~ Ltd.) was added ~t l90-C. The material ~a~ ~illed until homogeneous, removed from the mill, and compression molded into sheet~ for tensile strength and Rheo~ibron tests. The tensile tests were carried out according to AS~M D-638, D-412.
A general description of Rheo~ibron test~ can be found 6 ~30~
in Experiments in Pol~mer Science, E. A. Collins, J.
Bare~, and F. W. Billmeyer, Jr., Wiley-Interscience, New York (1973), pp. ~65-470. ~he measurements include elastic ~odulus E', viscous modulus E~, and loss tangent (tan ~, which is the ratio E"/E'. En is the measure of the amount of vibrational energy that is absorbed and converted to heat. Thus, the higher value vf E~ or tan ~, the greater the absorption of ~ound or of vibration will be. The experi~ental details as well as the result~ obtained ar~ given in Table I later in this text.
Comparative Example_1 The same polymer blend was prepared in the ~ame manner as in Example~ 1-5. This was ~urther blended with talc under the conditions employ~d for blending the polymers with mica in Examples 1-5. This composition was subjected to the ~ame tests, and the results are reported in Table I.
Example 6 A polymer blend of 2727 g ~tabilized PVC and 6364 g of the 6ame E/nBA/CO copQlymer as used in Examples 1-5 was prepared on ~ bilobal twin screw extruder under the following conditions:

Temp., C
Vacuum Barrel Zones Rate Pressure RPM ~kPa) 1 _~_ 1 4 Die Melt ka/hr (kPa) ` 100 91.9 143 192 190 191 175 183 7.62 869 The resulting blend (3632 g) was extrusion compounded with 4249 g of phlogopite mica (Suzorite ~TM] HK60, Marietta), 2497 g of phlogopite mica ~HK200, Suzorite ~TM~, ~arietta), and 552 g of aromatic processing oil (Sundex tTM~ r 7303, Sun Oil Co.) under the following conditions:

130~Zll Temp., C
Vacuum Barrel Zones Rate Pressure RPM ~kPal1 2 3 4 Die Melt kq/hr (kPa) _ lOO None 154191 189 192 176 184 5.08 917 The resulting composition was te~ted in the same manner as before. The results are given in Table I.
Exam~le 7 Another blend was prepared in the same - ~o manner as in Example 6 ~rom 3632 g of polymer hlend (same as in Example 6), 2497 g of HK200 mica, 3133 g of HK60 mica, and 454 g of processing oil (Sundex [TM]
790, Sun Oil Co,). This ~omposition also was tested in the same manner, and the results are reported in Table ! 15 I.
Examples 8 and 9 E/n~A/CO copolymer of the 6ame grade as in , Examples 1-5 (41.3 kg) and 19.8 kg of stabilized PVC
were mixed together in a Banbury mixer at 177~C until fluxed (about lO minutes). The material was placed on a roll mill and made into a sheet. A portion of this j sheeted blend (28~6 kg) was placed in $he Banbury mixer again along with #l-K mica (dry ground muscovite mica from English Mica Co.) and trioctyl trimellitate (TOTM, Monsanto) in the ratios indicated in Table I.
The material was then roll milled into a sheet and granulated. Its properties are given in Table I, below.

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~ 9 It can be seen from a comparison of Example 1 with Example C3 ~Comparative Example 3) that a blend of PVC with an E/nBA/CO copolymer gives at all test temperatures a hiqher En and tan ~ than a ystem based on ~n E/~A copol~mer. The cDmposition ~f the present invention is useful also at much higher temperatures than 140C.
Comparison of Examples 2 and 3 with Example Cl shows that mica gives superior results than talc in the same polymer ~ystem.
romparison of Exa~ple 2 with Example C2, representative of currently used commercial compositions, shows superior E~, ~an ~, and tensile l strength and improved upper use temperature for the ¦ 15 material of the present invention.
¦ Examples 4-9 further illustrate the ¦ invention, including the use o~ various optional ¦ additives and preparation by different processes.
~I Noise Reduction Measurements Noise reduction measurements were made on samples using a random noise generator. This random noise was directed through a duct having a square cross-section of 305x305 mm, terminated by an acoustic absorber. The noise reduction is expressed as ; 25 NR=L1-L2, where Ll and L2, expressed in dB, are the noise levels on opposite ~ides of the samples. The values of Ll and L2 were ~easured in eight octaYe bands from 63 to 8000 Hz by means of two Octave Band Analyzers (General Radio, Type 1933).
_ 30 The effectiveness of noi~e reduction is a function of both NR and the 6urface density ~f the sample, thin, light ~amples absorbing less sound than thicker, heavier samples ~f the same c~mpositi~n.
Sheets of the ~aterial were prepared and tested as shown in Table II, below. Table II gives the ~0 11 ~3~8;~1 values of noise reduction (decibels) as a function of frequency for the following examples.

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~ ~ 12 13 3082~1 It can be seen that the compositisns of the present invention containing about 57 to 62% of mica were as effective in ~ound deadening as a prior art composition (C4, Comparative Example 4) containing 72.5% of calcium carbonate. Based on the weight of filler, the compositions of the present invention thus have better sound deadening properties.
Low Temperature Properties Exam~le 12 and Comparative Examples 6 and Z
Compositions containing PVC, ethylene copolymer, and mica in the respective ratios of 10:40:50 were prepared by the above-described techniques. The ethylene copolymer had the following compositions:
~xample Ethylene Copolymer !~ 12 E~nBA/C0, 60:30:io Il C6 E/VA/C0, 62:28/10 li C7 E/VA, 32:68 PVC was a formulation containing 100 parts of PVC, 10 parts of epoxidized ~oybean oil (Paraplex [TM] G68, Rohm & Haas), 3 part~ of Ba-Cd laurate ~tabilizer (Mark [TM] WS, Witco), 1 part of an alkyl aryl phosphite ~tabilizer (Mark [TM] 517, Witco), 1.8 parts of dilauryl thiodipropionate, and 0.7 parts of an antioxidant ~Irganox ~TM] 1010, Ciba-Geigy). Mica was the HK200 type.
The torsion modulus o~ each one of these samples was measured at room temperature and at a low temperature (-10C and/or 0C), according to ASTM
D-1043. The results o~ these measurements ar~ given in Table III, below.

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TABLE III
TORSION MODULUS (MPa! AS A FUNCTION OF TEMPERATURE
Exam~le 23C 0C -10C

C~ 33 108 --The table 6hows that the composition of the present invention (Example 12) has far superior low temperature properties when compared to materials made from E/VA copolymer ha~ing high vinyl acetate content.
The compositions of the present invention remain much more flexible at low temperatures and would thus be expected to be able to retain to a higher degreP the ability to dampen vibration and absorb ~ound at low temperatures.
Examples 13 and 14 and ComparativE Examples C8 - Cll The following polymer composition was prepared. First, PVC was compounded as follows:
., Pts.
. Geon 30 (TM) PVC (B.F. Goodrich) 100 Drapex 6.~ (T~) epoxidized soybean oil (Witco) 15 Phosphite PVC stabilizer Ca/Zn PVC ætabilizer 3 Stearic acid 0.25 Antioxidant ! (Irganox ~TM] 1010 Ciba-Geigy) 1 This composition, 35 g, was melt-blended ~ with 65 g of an E/nBA/CO 60:30:10 ~vpolymer to give a compatible blend, which then was used in the tests.
The test compositions as well as the Rheo Vibron data are given below in Table IV.

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~ccordingly, the mica-containing compositions can be expected to provide much better ~ound ~bsorption.

Claims (20)

1. A composition suitable for the manufacture of noise reduction or vibration damping articles, said composition consisting essentially of a blend of a) about 10-90% of a copolymer of ethylene with at least one organic monomer X capable of being polymerized to a homopolymer having a glass transition temperature, Tg, of less than about -20°C and selected from the group consisting of esters of unsaturated C3-C20 mono- and dicarboxylic acids, vinyl esters of saturated C2-C18 carboxylic acids, and vinyl alkyl ethers wherein the alkyl group has 1-18 carbon atoms, and an additional monomer Y selected from the group consisting of ethylenically unsaturated C3-C20 carboxylic acids, carbon monoxide, and sulfur dioxide;
b) about 90-10% of a vinyl chloride homopolymer or a copolymer of vinyl chloride with another ethylenically unsaturated comonomer selected from the group consisting of C2-C5 hydrocarbons, vinyl esters, acrylonitrile, acrylic esters, vinylidene chloride, esters of unsaturated carboxylic acids, and vinyl ethers:
both percentages being based on the total weight of the polymers in the blend, which is about 10-80% of the total weight of the composition; and c) about 20-90% of mica, based on the total weight of the composition

2. A composition of Claim 1 wherein monomer X is an acrylate ester.

3. A composition of Claim 2 wherein monomer Y is carbon monoxide.

4. A composition of Claim 1 wherein monomer X is n-butyl acrylate, and monomer Y is carbon monoxide.

5. A composition of Claim 1 wherein the range of monomer X in the ethylene copolymer is about 1-60 weight %.

6. A composition of Claim 5 wherein the range of monomer X in the ethylene copolymer is 5-60 weight %.

7. A composition of Claim 6 wherein the range of monomer X is 5-50 weight %.

8. A composition of Claim 1 wherein the range of monomer Y is about 1-30 weight %.

9. A composition of Claim 8 wherein the range of monomer Y is 3-30 weight%.

10. A composition of Claim 9 wherein the range of monomer Y is 3-10 weight %.

11. A composition of Claim 1 wherein mica is phlogopite.

12. A composition of Claim 1 wherein polymer b) is polyvinyl chloride.

13. A composition of Claim 1 wherein, in addition to mica, there also is present in the composition at least one other inorganic filler, the total amount of mica plus the other organic filler material being at most 90 weight % of the composition.

14. A composition of Claim 1 wherein the amount of copolymer of ethylene copolymer a) in the blend is 40-90%, and the amount of vinyl chloride homopolymer or copolymer (b) is 60-10%, both being based on the total weight of polymers in the blend.

15. A composition of Claim 14, wherein the amount of copolymer of ethylene a) is 50-75%, and the amount of vinyl chloride homopolymer or copolymer b) is 50-25%, both being based on the total weight of the polymers in the blend.

16. A composition of Claim 15 wherein monomer X is an acrylate ester.

17. A composition of Claim 16 wherein monomer Y is carbon monoxide.

18. A composition of Claim 17 wherein monomer 15 wherein monomer X is n-butyl acrylate.

19. A composition of Claim 18 wherein monomer Y is carbon monoxide.

20. A composition of Claim 15 wherein polymer b) is polyvinyl chloride.