GB1583892A

GB1583892A - Sound deadener

Info

Publication number: GB1583892A
Application number: GB2534877A
Authority: GB
Original assignee: Bostik Ltd
Current assignee: Bostik Ltd
Priority date: 1976-06-18
Filing date: 1977-06-17
Publication date: 1981-02-04
Also published as: AU2618677A; CA1089606A; AU511196B2

Description

(54) IMPROVEMENTS IN OR RELATING TO SOUND DEADENER (71) We BOSTIK LIMITED, a British Company of Ulverscroft Works, Ulverscroft Road, in the City of Leicester, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention is concerned with improvements in or relating to sound deadener and is especially concerned with a sound deadener sheet softenable by heat to wilt into conformity and adhesive engagement with a contoured metal surface but resistant to running and flow at temperatures higher than the temperature at which the sheet wilts into adhesive engagement with the contoured metal surface, comprising a mineral-filled bitumen composition containing a small amount of vulcanized vegetable oil.

Damping of vibration in thin sheet material for example sheet metal floor pans of automobiles is important to reduce noise levels. It has been proposed to adhere a composition sheet to a metal panel for vibration damping purposes by placing the composition sheet on the metal panel before the automobile body goes through heating ovens employed in finishing the body. According to this proposal heat of these ovens softens the composition sheet so that it wilts into conformity with the panel and adheres to the metal surface. A variety of heat softenable compositions, for example mixtures of bitumen, fillers and/ or fibres, and a natural or synthetic hydrocarbon rubber, ie.g. a butadiene styrene copolymer synthetic rubber, have been proposed for this use.

Tests established for acceptance of materials for vibration damping of metal floor pans by automobile manufacturers require that the sheet material wilt into conformity with and adhere to the metal of the floor pans at temperatures at least as low as temperatures reached in the heating ovens during finishing of the body, but that flowing or running of the material at sub stantially higher temperatures shall not exceed a limited value. These tests can be met by using substantial proportions of a hydrocarbon rubber in the composition. However, use of such proportions of rubber, which is much more expensive than bitumen, markedly increases the cost of the sheet material and is believed to reduce the vibration damping efficiency.

It is an object of the present invention to provide an improved sound deadening sheet material of comparatively low cost.

It has now been found that a sheet composition having improved resistance to undesired high temperature flow together with good conformability and adhesion properties may be based on a sound deadener composition comprising bitumen, filler and a limited amount of a vulcanized vegetable oil with the bitumen. It has been found that a filled bituminous sound deadener sheet according to the present invention lìas an unexpected combination of characteristics in heated condition particularly fitting it for union with shaped metal, such as in use of the sheet material as a sound deadener for automobile floor pans.

The present invention provides in one of its aspects a sound deadener sheet softenable by heat to wilt into conformity and adhesive engagement with a contoured metal surface but resistant to running and flow at temperatures higher than the temperature at which the sheet surface, said sheet being formed of a mixture of mineral filler and a binder, said binder comprising bituminous material and an amount of vulcanized vegetable oil of from 1.5% to 3.5% by weight of the binder.

The present invention provides in another of its aspects a sound deadener composition comprising from 60 to 85 % by weight of finely divided inorganic filler, from 40 to 15% by weight of a binder comprising by weight of the binder from 45 to 70 % bituminous material having a penetration value less than 300 and a softening point in the range 60"F to 110 F, from 5 to 20 % of elastomeric modifier, from 15 to 25% of uintaite and from 1.5 to 3.5% of a reaction product of unsaturated vegetable oil with sulphur or sulphur derivative.

The accompanying drawing is an angular elevational view of a contoured metal sheet used for testing thermal properties of sound deadener sheet material.

The term "vulcanized vegetable oil" where used herein refers to a solid nonthermoplastic product of reacting vegetable unsaturated oil such as linseed oil, cottonseed oil, soybean oil or others with sulphur or with sulphur derivatives such as sulphur monochloride, and sulphur dichloride.

These materials are commercially available for example under the Trade Mark "FAC TICE" from the American Cyanid Company. The product from reaction of the vegetable oil with sulphur is preferred for the present use. These vulcanised oils are most commonly used as extenders, processing aids or plasticisers for natural and synthetic rubbers. However, in the present case, the vulcanised oil coacts with the bitumen to provide, in a sheet of the minmineral filled bitumen sound deadner composition of the present invention, a unique combination of good characteristics for wilting and conforming and bonding to a ribbed and/or curved metal plate when heated, and of resistance to running or flow at high temperatures.

The binder preferably also includes, in addition to bituminous material and vulcanised vegetable oil, an elastomeric modifier to reduce brittleness and improve elasticity and resistance to tearing. Elastomeric modifiers for inclusion in the compositions of the present invention may be hydrocarbon elastomers or copolymers of ethylene with non-hydrocarbon monomers which may be known for inclusion in bituminous compositions.

Hydrocarbon rubbers or elastomers which may be used as elastomeric modifier for combination with bitumen and vulcanised vegetable oil in the binder for the sound deadener composition include natural rubber, synthetic polymer or copolymer rubbers including so-called thermo-plastic rubbers, and reclaim rubber. Suitable synthetic ruDDers include styrene-butadiene copolymer synthetic rubber, butadiene styrene block copolymers, e.g. "Kraton" 1107 manufactured by the Shell Chemical Co., butyl rubber, polyisobutylene, ethylenepropylene copolymers (EPM), ethylenepropylene-diene terpolymers (EPDM) and mixtures of these. A preferred range of Mooney values is from 20 to 35. Preferred ethylene copolymers for use as elastomeric modifiers include bitumen-soluble copolymers containing from 40% to 98% preferably at least 50% and more preferably from 60% to 90% by weight of ethylene with from 60% to 2% preferably from 40% to 10% by weight of a mono-unsaturated polymerisable compound such as a lower alkyl ester of acrylic or methacrylic acid in which the alkyl radical has from 1 to 6 carbon atoms.

Bituminous materials employed in the binder in the compositions of the present invention are preferably asphaltic bitumens and may be either natural asphalt or residue from the distilation of petroleum.

The asphaltic bitumens are commercially available in penetration values up to about 300 as determined by ASTM method D-573 at 77"F. The softening points (Ball and Ring), as determined by ASTM method D36-70 of the bitumens preferably employed in the binder are in the range of from 60"F to 1100F, preferably from 60"F to 80"F.

With the preferred bitumens uintaite, a natural hard thermoplastic asphalt, is also preferably included in the binder; it has been found that addition of uintaite to the composition materially improves the breaking strength and tear strength of the sound deadener sheet. As uintaite one may use material supplied under the Registered Trade Mark Gilsonite having a melting point of from 270"F to 280"F and a penetration value at 77"F of less than 1.

A preferred formulation of binder of the present sound deadener, involves combining in balanced ranges of proportions, bitumen, elastomeric modifier and uintaite together with a small but effective amount of vulcanised vegetable oil to control the softening and flow properties together with good sound deadening efficiency and low cost.

Based on the total weight of the binder, useful proportions in terms of weight percentages will include from 45% to 70% preferably 50% to 60% by weight of bitumen, from 5% to 20% of elastomeric modifier, from 15% to 25% of uintaite, and from 1.5% to 3.5% preferably from 2% to 2.5% of vulcanised vegetable oil.

In a sound deadener according to the invention, mineral filler for combination with the binder may be any of a variety of finely divided inorganic materials such as ground limestone, suitably a dolomitic limestone, whiting, barytes, calcium carbonate, clay, slate, and mica. Preferably, the particle size should be such that 80% will pass a 200 mesh screen (U.S. Standard Sieve) and none will be held on a 35 mesh screen.

The filler content of the sound deadener sheet of the present invention may be between 60% to 85% preferably from 75% to 85% by weight and tbe binder correspondingly from 40% to 15% preferably from 25% to 150/, by weight based on the weight of the sheet.

A sound deadener sheet according to the invention may be formed in any conventional manner, for example by mixing to gether the bitumen, elastomeric modifier, uintaite and vulcanized vegetable oil in a heated vessel and then adding the mineral filler to the hot mixture and mixing to uniformity. The mixture is then formed into a sheet by calendar rolls or other suitable device. For use as a sound deadener for sheet metal floor pans for automobiles, sheets are preferably from 0.05 inch to 0.1 inch in thickness.

A sound deadener sheet for use with an automobile floor pan is merely laid on the upper surface of the floor pan and is required to soften and wilt into conformity with the contour of the floor pan during the heating used in finishing the automobile body, but must also not be softened to a condition in which it runs excessively so as to lose its uniformity and to run or flow past the areas where it is desired. Tests for acoeptance of sound deadener sheet material involve laying a 2 x 10 inch strip 10 of the sound deadener sheet across a metal sheet 12 contoured as shown in the drawing and heating the assembly to 275"F for one-half hour. As shown in the drawing, the metal sheet 12 has a flat, horizontally disposed first section 14, a section 16 extending downward at right angles to the first section and a further horizontally disposed section 18. The section 18 is formed with small grooves 20. It is required that after the heating, the strip 10 has sagged or wilted from its original position and flat shape shown in broken lines in the drawing into conformity not only with the downwardly angled section 16 but also with the small grooves 20 so that there is not more than 1/16 inch gap between the strip 10 and the contoured metal section 12 at any point.

A further test to establish that the sheet does not flow or run excessively involves disposing a 2 x 6 inch strip 22 on the flat portion 14 of the contoured metal surface with a portion 30 of the strip, as shown in broken lines in the Figure, extending beyond the edge of the flat portion 14 by an amount which would bring the edge 26 of the portion 30 against an upper score mark 28, on the downwardly extending section 16 when the strip 22 has bent downwardly into engagement with the vertical portion 16 of the metal sheet 12. It is required that on heating the sample to 4000F the downwardly bent portion 30 of the strip 22 must not flow more than 3/8 of an inch in one hour, i.e. must not have flowed down to the lower score mark 32 on the vertical portion 16 of the metal surface. Additional requirements are that the sheet have a breaking tensile strength of at least 0.1 pound per mil thickness and inch width.

There now follows a description of three examples of sound deadener compositions in sheet form which are illustrative of the invention. It is to be understood that these examples have been selected for description to illustrate the invention by way of example only and not by way of limitation thereof.

Example 1 The following is a formula of a sound deadener composition for use in connection with an automobile floor pan: - Parts by Component weight Finely divided dolomitic lime stone 80 CaO 0.6 Butadiene styrene copolymer rubber (Mooney viscosity 27 to 35) 3.2 Gilsonite 4.5 Low melting point bitumen 11.2 Vulcanized vegetable oil (Factice No. 11 Brown) 0.5 The bitumen was a commercial product known as 22L, obtained from Pioneer Division of Witco Chemicals Company having a Ball and Ring melting point of about 80"F and a nominal penetration value of 300 at 77"F by ASTM method of D-5-73.

The finely divided dolomite limestone had a particle size such that about 80% will pass a 200 mesh screen and none will be retained on a 35 mesh screen, the screens being U.S. Standard Sieve.

The butadiene styrene copolymer rubber, Gilsonite and vulcanized vegetable oil were introduced into an internal mixer sold under the Trade Mark BANBURY and worked together at 320"F. At this point, half of the bitumen and half of the finely divided dolomitic limestone were added and when they had been thoroughly mixed in, the remainder of the components were added and thoroughly mixed in. The mixture was discharged from the mixer and sheleted out between the rolls of a calender to a thickness of 0.070 of an inch + 0.005 of an inch.

The sheet material was subjected to the conformity and flow tests described above in the specification and successfully passed these tests.

By way of comparison, a composition identical with the formula given above except that it did not include vulcanized vegetable oil was prepared and formed into a sheet. When the sheet was subjected to conformity and flow tests, it was found that the material flowed badly during the 400"F portion of the test.

Example 2 The following composition was prepared for use as a sound deadener sheet for an automobile floor pan.

Parts by Component weight Finely divided dolomitic lime stone 79.7 CaO 0.6 Ethylene propylene diene ter polymer (EPDM) 1.0 Gilsonite 3.0 Intermediate melting point bitumen 15.2 Vulcanized vegetable oil 0.5 The composition was mixed and formed into a sheet following the procedure of Example 1. The resulting sheet material was subjected to the conformity and flow tests described above in the specification and successfully passed these tests.

Example 3 The following composition was prepared for use as a sound deadener sheet material.

Component weight Parts by Finely divided dolomitic lime stone (200 mesh) 80.5 CaO 0.6 Ethylene-propylene copolymer 3.2 Vulcanized vegetable oil 0.5 Low melting point bitumen 11.2 Gilsonite 4.0 The ethylene-propylene copolymer was the commercial product known as Vistalon 404 ('Vistalon' is a Registered Trade Mark), a product of Enjay Chemical Company having an ethylene content of about 40%, a propylene content of about 60% and a Mooney value of 35 to 45 and the bitumen was the same bitumen material used in Example 1.

The composition was mixed and formed into a sheet following the procedure of Example 1. The resulting sheet was subjected to the conformity and flow tests described above in the specification and successfully passed these tests.

WHAT WE CLAIM IS: 1. A sound deadener sheet softenable by heat to wilt into conformity and adhesive engagement with a contoured metal surface but resistant to running and flow at temperatures higher than the temperature at which the sheet wilts into adhesive engagement with the contoured metal surface, said sheet being formed of a mixture of mineral filler and a binder, said binder comprising bituminous material and an amount of vulcanised vegetable oil of from 1.5% to 3.5% by weight of the binder.

2. A sound deadener sheet according to claim I in which said mixture comprises from 60% to 85% by weight of mineral filler and from 40% to 15% by weight of said binder.

3. A sound deadener sheet according to either one of claims 1 and 2 in which the binder also includes an elastomeric modifier.

4. A sound deadener sheet according to claim 3 in which the elastomeric modifier is a hydrocarbon elastomer.

5. A sound deadener sheet according to claim 4 in which said elastomeric modifier is a copolymer of ethylene and propylene.

6. A sound deadener sheet according to claim 4 in which said elastomeric modifier is a terpolymer of ethylene, propylene and a diene.

7. A sound deadener sheet according to claim 4 in which said elastomeric modifier is a butadiene styrene copolymer rubber.

8. A sound deadener sheet according to claim 3 in which said elastomeric modifier is a copolymer of ethylene and an alkyl ester of acrylic or methacrylic acid in which the alkyl radical has from 1 to 6 carbon atoms and in which the ethylene is at least 506/o of the copolymer.

9. A sound deadener sheet according to any one of claims 3 to 8 in which the binder comprises from 5% to 20% by weight of binder, of elastomeric modifier.

10. A sound deadener sheet according to any one of claims 3 to 9 in which said binder comprises from 15% to 25% by weight of uintaite and 45 to 70% by weight of a bitumen having a softening point (Ball and Ring) of from 60"F to 1l00F.

11. A sound deadener sheet according to claim 2 in which said mixture comprises from 75% to 85% by weight of mineral filler, the particles of mineral filler being of a size less than that which will pass a 325 mesh screen (U.S. Standard Sieve) and from 25% to 15% by weight qf a binder and, said binder comprising from 50% to 60% Ojo by weight of bitumen having a softening point between 60"F and 80"F, from 5% to 20% by weight of an elastomeric modifier, from 15% to 25% by weight of uintaite, and from 2% to 2.5% by weight of a vulcanized vegetable oil.

12. A sound deadener composition comprising from 60 to 85% by weight of finely divided inorganic filler, from 40 to 15% by weight of a binder comprising by weight of the binder from 45 to 70% bituminous material having a penetration value less than 300 and a softening point in the range 60"F to llO"F, from 5 to 20% of elastomeric modifier, from 15 to 25% of uintaite and from 1.5 to 3.5% of a reaction product of unsaturated vegetable oil with sulphur or sulphur derivative.

13. A sound deadener sheet substantially as hereinbefore described with reference to Example 1 or Example 2.

14. A sound deadener sheet substan

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Parts by Component weight Finely divided dolomitic lime stone 79.7 CaO 0.6 Ethylene propylene diene ter polymer (EPDM) 1.0 Gilsonite 3.0 Intermediate melting point bitumen 15.2 Vulcanized vegetable oil 0.5 The composition was mixed and formed into a sheet following the procedure of Example 1. The resulting sheet material was subjected to the conformity and flow tests described above in the specification and successfully passed these tests. Example 3 The following composition was prepared for use as a sound deadener sheet material. Component weight Parts by Finely divided dolomitic lime stone (200 mesh) 80.5 CaO 0.6 Ethylene-propylene copolymer 3.2 Vulcanized vegetable oil 0.5 Low melting point bitumen 11.2 Gilsonite 4.0 The ethylene-propylene copolymer was the commercial product known as Vistalon 404 ('Vistalon' is a Registered Trade Mark), a product of Enjay Chemical Company having an ethylene content of about 40%, a propylene content of about 60% and a Mooney value of 35 to 45 and the bitumen was the same bitumen material used in Example 1. The composition was mixed and formed into a sheet following the procedure of Example 1. The resulting sheet was subjected to the conformity and flow tests described above in the specification and successfully passed these tests. WHAT WE CLAIM IS:

1. A sound deadener sheet softenable by heat to wilt into conformity and adhesive engagement with a contoured metal surface but resistant to running and flow at temperatures higher than the temperature at which the sheet wilts into adhesive engagement with the contoured metal surface, said sheet being formed of a mixture of mineral filler and a binder, said binder comprising bituminous material and an amount of vulcanised vegetable oil of from 1.5% to 3.5% by weight of the binder.

14. A sound deadener sheet substan

tially as hereinbefore described with reference to Example 3.

15. A composition according to claim 12 substantially as hereinbefore described with reference to Example 1 or Example 2.

16. A composition according to claim 12 substantially as hereinbefore described with reference to Example 3.