DE2533579A1 - PROCEDURE FOR DAMPING SHOCK - Google Patents

Description

Method for drying buttocks

The present invention relates to an improvement in a method of cushioning impact. More specifically concerns they provide an assembly that includes a movable part within an enclosing chamber and a rubber seal includes and the filling of the assembly with a vibration or shock-absorbing amount of a liquid composition, which comprises a silicone oil, a swelling agent for the rubber and a lubricity additive for the oil.

U.S. Patent 2,398,187 discloses compositions for use as damping fluids in hydraulic machines for absorption of impact energy disclosed, such as "shock absorbers, artillery return impact mechanisms, Door buffers, railroad car couplings, support struts for aircraft and the like. These liquids that mainly comprised of silicone fluids, with the remainder of the

609808/0731

2 ς 1 τ ^ 7 Q

liquid medium is an organic lubricant, should according to this US-PS have various essential characteristics, one of which is essential, that it is not a substantial source of the rubber parts.

Almost all conventional shock absorbers / are based on the same principle > ie they use a structural unit that is a movable one

one

Part within / enclosing chamber and they have at least a rubber seal, the assembly with a predetermined amount of a hydraulic damping fluid composition is filled, which meets certain requirements, such as a wide range of use under extremely variable Operating conditions. In such systems the rubber seals are the weak points and it has long been believed that it is essential to use a liquid that does not cause the rubber parts to swell to an essential extent, as in the aforementioned US patent.

While the present invention is not limited to use in any vehicle, it has a broad scope Applicability in this area. For example, in racing motorcycles in particular, and in normal motorcycles in general, the front fork is a shock absorber or hydraulic damper. The "stiffness" of this shock absorber affects the control of the wheel and determines the hardness or softness of the ride. For many years the hydraulic damper was incorporated into the front forks of motorcycles a mineral oil based liquid with a relatively low viscosity. It was found that under harsh racing conditions and / or under the influence of large changes in temperature, the motorcycle forks, which have been filled with such liquids, become more unpredictable Acting wisely by being sluggish at low temperatures and so against the ground at high temperatures suggested that the free handling was impaired. To overcome these problems, certain motorcycle manufacturers have applied the teachings of US Pat. No. 2,398,187 and doing so in general obtained good results, but occasionally also

8/0731

sager had to deal with, for the most part, the loss of fluid from the assembly or the wear and tear between the moving ones Parts in it were to be attributed.

It has been found in the present invention that improved Liquids for such purposes can be compiled and that such fluids in a variety of machines can be used usefully. It was surprisingly found that, in contrast to the teachings of the aforementioned U.S. Patent on the addition of an additive to a liquid polyorganosiloxane that causes significant swelling of the used in the seals Gums has the effect of reducing the number of failures that can be attributed to the fluid itself to almost zero can be. In addition, a considerable improvement in the function as a hydraulic damping fluid can be achieved, when a small but effective amount of a compound is added to the composition that enhances exercise capacity of a film formed from the polysiloxaa is increased. Since also in many areas vehicles drive over rough terrain, with water, salt water or the like on top of that and a protective plating has sometimes been rubbed off the shock absorbers under these conditions, in some embodiments it is it is desirable to add a corrosion inhibitor to protect metallic parts from corrosion.

According to the present invention, joints are made by means of a structural unit damped, which comprises a movable part within an enclosing chamber and has at least one rubber seal, by applying shock pressures by means of a hydraulically damping amount of a composition present in the chamber the moving part transmits, the composition comprising:

(i) a major amount of a liquid organopolysiloxane which the organic radicals are selected from optionally halogen-substituted monovalent hydrocarbon radicals, cyanoalkyl radicals and mixtures thereof, the radicals having 1 to 8 carbon atoms have and at least some of the groups are alkyl groups with up to 3 carbon atoms,

6Ώ98Ώ8 / 0731

(ii) a minor amount of a compound or a mixture of compounds which are compatible with component (i) and which can cause significant swelling of the rubber seal

(iii) a small but effective amount of up to 15 wt .- /? from the total amount of the composition of a compound which increases the load-bearing capacity of a film made from component (i).

The most suitable structural unit for the method according to the invention will comprise a shock absorber with an elongated metallic cylindrical pressure chamber and a metallic one Piston which is arranged in this chamber in a returnable manner and which is connected to a piston rod which extends out of the chamber extends outward and wherein the rubber seal comprises a natural rubber or a synthetic diene rubber such as polyisoprene, polybutadiene or a copolymer of butadiene with a comonomer such as styrene or acrylonitrile and the like. In the most useful Embodiments of the present invention, the shock absorber is an element in a vehicle, particularly in a motorcycle and especially the front fork of a motorcycle and especially the front fork of a racing motorcycle.

In preferred compositions for use in the present Invention encompass the organic radicals of component (i), the organopolysiloxane, monovalent hydrocarbon radicals with 1 to 8 carbon atoms and preferably they are selected from alkyl radicals with 1 to 3 carbon atoms and phenyl radicals, alkyl radicals having 1 to 3 carbon atoms are particularly preferred. Most preferred are methyl radicals.

The organopolysiloxanes can generally be any of the liquid Organosilicon polymers described in U.S. Patent No. 2,938,187 are described as useful as hydraulic fluids. Exemplary of the organic radicals in such compounds are Methyl, ethyl, propyl, isopropyl, butyl, amyl, hexyl, heptyl and Octyl, both straight and branched, cyclopentyl, cyclohexyl etc., aryl and alkaryl, such as phenyl, mono- and dialkylphenyl,

609 ^ 08/0731

such as tolyl and xyIyI, ethylphenyl etc., arylalkyl, such as eenzyl, Phenylethyl and the like, alkenyl, such as methallyl, allyl and the like, as well as all such radicals that carry halogen substituents, such as chlorine, bromine etc., e.g. chloroethyl, bromophenyl, chlorobenzyl etc., as well as cyanoalkyl radicals, e.g. cyanoethyl, cyanopropyl and similar. These liquid polymers are made by methods known to those skilled in the art, such as hydrolysis of organohalosilanes, by condensation of the hydrolysis products obtained or by hydrolysis of a mixture of cyclic Siloxanes, etc. These known methods are described, for example, in the aforementioned U.S. Patent 2,398,187 and in the book by Noll "Chemistry and Technology of Silicones ", Academic Press, New York (1968) and in the publications cited therein.

Particularly preferred as the polysiloxane component (i) is in that according to the invention Process a compound of the following formula

(CHjSi-O 4- si- 0-4-Si (CH,),
3 Ii 3 3

where η is a number large enough to represent the liquid to impart a viscosity in the range of 5 to 4000 centistokes at 25 ° C. These materials can be manufactured by processes described in the aforementioned references and they are also available in a variety of Viscosity ranges from a number of manufacturers, e.g., General Electric Company of Waterford, New York.

In the compositions of the present invention, the rubber swelling component (ii) comprises a compound or mixture of compounds that is compatible with the organopolysiloxane and a considerable swelling of the rubber seal, which in the Sxiss damping assembly is used to cause. The type of connection is not particularly critical and the person skilled in the art knows many connections that are suitable for this "purpose.

€ 09808/0731

in addition to the compatibility with the silicone and the swelling Effect on the rubber used in the individual case, the component (ii) should not have a corrosive effect and it should with normal Temperatures are essentially non-volatile. The suitability of a connection is easily determined by having produces a compatible mixture of it with the polysiloxane and immerses the rubber to be used in it for 24 hours and then determines whether the external dimensions of the rubber have increased.

The use of is particularly useful as component (ii)

(A) a liquid organic phosphate, in which the organic radicals are selected from monovalent monovalent ones that are optionally halogen-substituted Hydrocarbon radicals and their mixtures, where the Have radicals 1 to 8 carbon atoms,

(b) a liquid diester which is an alcohol component having a hydrocarbon radical having 1 to 12 carbon atoms and has a dicarboxylic acid moiety with 4 to 12 carbon atoms as

(c) Mixtures of (a) and (b).

Examples of organic phosphates are those in which the monovalent hydrocarbon radicals, alkyl, alkenyl, cycloalkyl, Cycloalkenyl, aryl, alkaryl, aralkyl and their halogen-substituted derivatives are as described above in connection with of component (i) were mentioned in detail. Suitable organic phosphates are therefore triethyl phosphate and triisopropyl phosphate Tributyl phosphate, trioctyl phosphate, triphenyl phosphate, Tricresyl phosphate, tribromophenyl phosphate and the like. A special one the preferred phosphate is tributyl phosphate.

Also as component (ii) is a liquid diester of an alcohol having 1 to 12 carbon atoms and a dicarboxylic acid having 4 to 12 carbon atoms, either alone or in a mixture, suitable as a swelling agent for the rubber seals. The alcohol component can be aliphatic, cycloaliphatic, unsaturated, straight-chain or branched, further aryl, alkaryl, aralkyl etc. and the di-

609808/0731

Likewise, carboxylic acid can be alkyl, cycloalkyl, unsaturated, aryl, alkaryl, and the like. Alcohol and acid units in the diester can be substituted by halogen, for example by chlorine or bromine. Suitable components (b) of this type can be, for example, the following: dimethyl sebazate, dioctyl succinate, dibenzy azelate, diisooctyl sebazate, dioctyl azelate. Preferably component (b) will be dioctyl azelate. The amount of the rubber-swelling component (ii) may be within the broad scope of a small but effective amount, for example 0.1 wt -.% To 10 wt -.% Or more vary depending upon the weight of the total composition. If component (ii) comprises a mixture of two compounds, for example a phosphate and a diester, then it is preferred that each of the mixture ingredients be present in approximately the same amount.

The lubricity additive (iii) serves to increase the load-bearing capacity a film of the siloxane liquid component (i). This property is measured according to known methods, e.g. by measuring the weight required to cause seizure of moving bearings that are involved with a film of the liquid to be measured. One such measurement method is in the above book Described by Noil on page 469. Another measurement method is known from ASTM method 2266, in which the load capacity of a liquid is given as the diameter of a scar or scratch that occurs under constant load and Speed forms when bearings are lubricated with the liquid to be analyzed and rotate against each other. Lubricity Additives reduce the scar diameter in such a test.

Suitable additives to increase the load capacity of the Liquid in the context of the present invention can in general comprise any material that interacts with the silicone liquid is compatible and that increases the load-bearing capacity. Many additives are known for this purpose. For example can be used for this: methylchlorophenylsilane, Diels-Alder-

Addition products of vinylsilanes and hexachlorocyclopentadiene, chlorinated diphenyls and organic disulfides, chlorinated and fluorinated aliphatic hydrocarbons, chlorinated and bro- tertiary fatty acids with 1 to 12 carbon atoms, esters of lower chlorinated fatty acids and thioglycol esters, esters of phosphoric acids, Copper, magnesium and lead salts of aliphatic carboxylic acids having 4 to 9 carbon atoms and the like. These additives are in the above-mentioned book by Noil on page 470 and the in the publications cited in the book.

The amount of the lubricity additive (iii) is in the range of a small but effective amount, for example from 0.1 wt -.% To 15 wt .- $ or more of the total weight of the composition. Component (iii) preferably comprises a metal salt of a phosphoric acid partial ester or a partial thioester. A copper, manganese, lead or zinc salt thereof is preferably used. A zinc dialkyldithiophosphate is particularly preferred as component (iii) and zinc diisopropyldithiophosphate is very particularly preferred. The latter compound can be prepared by known processes and it is also available from Lubrizol Corp., USA under the product name LUBRIZOL 1060.

In certain embodiments, for example when the shock absorber includes metallic elements which can corrode on contact with mass, and in particular on contact with salt water, it is preferred to use an additional corrosion-inhibiting component (iv) in the composition, which in a small but effective manner amount for example from 0.1 up to 10 wt -.% or more of the total weight of the composition ^ may be present. Such compounds can vary widely in their chemical nature and are part of a family of compounds known to those skilled in the art. They should form a homogeneous solution with the other components of the composition. However, such compounds will preferably comprise copper, magnesium, lead or zinc salts of organocarboxylic acids having k to 16 carbon atoms and are particularly preferred as component (iv)

609808/0731

Zinc naphthenate. This connection can be made by known methods and is also commercially available.

Preferred compositions for use in the invention Procedures include:

(i) a dimethylpolysiloxane liquid with a viscosity of 5 to 1000 centistokes at 25 ⁰ C,

(ii) 0.5 to 5 wt. ϊ tributyl phosphate and 0.5 to 5 wt. Ϊ di-acetyl azelate,

(iii) 0.5 to 15 wt -.% zinc diisopropyl dithiophosphate and (iv) 0 to 5 wt -.% zinc naphthenate, wherein all percentages are based on the total weight of the composition.

Tests have shown that particularly preferred compositions for use in the method of the invention are as follows Components include:

(i) 90 to 95 Ge \ i .-% of a Dimethylpo ^ siloxane Plüssigkeit having a viscosity of 50 to 150 centistokes at 25 C, (ii) 2 to 4 wt -.% of dibutyl phosphate and 2 to 4 wt -.% dioctyl azelate ,

(iii) 0.5 to 10 wt. # zinc diisopropyl dithiophosphate and (iv) 0.1 to 2.5 wt. # zinc naphthenate, all percentages being based on the total weight of the composition.

The invention is explained in more detail below with the aid of examples .

example 1

The following composition was made:

Components parts by weight

(i) silicone fluid

Trimethylsilyl-terminated Polydimethylsiloxane with a viscosity

of 100 centistokes at 25 ° C 92.5

£ 09808/0731

Components parts by weight

(ii) Rubber Swell Additive

(a) tributyl phosphate 3.0

(b) dioctyl azelate - 3.0

(iii) Stress additive

Zinc diisopropyl dithiophosphate 1.0

(iv) corrosion inhibitor

Zinc naphthenate 0.5

The properties of this composition have been determined and are summarized below:

Lubricity according to ASTM 2266

40 kg load, 1200 revolutions / min., 75 ° C 1.8 mm scar

Rubber swelling

Styrene butadiene copolymer + 3%

Butadiene / acrylonitrile copolymer (Buna N) + 0.5 %

Corrosion test with a drop of water (polished steel specimen with indentations, immersed in the liquid) passed

A certain amount of the liquid composition was placed in the cylindrical chamber of the front fork of a racing motorcycle. The motorcycle was driven over rough terrain for 6 days. The composition worked well and was effective at damping Shocks and there was no failure in the shock absorber due to leaks in the rubber seal, wear of brushes, and corrosion on any parts of which the protective chrome coating had been withdrawn.

8/0731

Example 2

The procedure of Example 1 was repeated, increasing the strength of zinc diisopropyldithiophosphate to 10 wt% based on the total weight of the composition. The Yersehlei beet diameter gauge (ASTM 2266) has been further reduced to 1.2 mm.

Comparative example IA

The procedure of Example 1 was repeated with the exception that the shock absorber chamber is only filled with the siloxane component (i) which is the ilomponenten in comparison to example 1 (ii), (iii) and (iv) not included. Even with this composition a test has been carried out and the properties determined are summarized below:

Lubricity according to ASIM U-2266

at 40 kg load, 1200 revolutions / round, 75 ⁰ C 2.3 mm barbel

G ummique1lung

Styrene butadiene copolymer - 3 %

Butadiene Acrylonitrile Copolymer - 10 %

The corrosion test with the water droplet failed.

This shows that this composition, which only consists of the Component (i) of Example 1, which is a preferred embodiment of US Pat. No. 2,398,187, is actually one Reducing the dimension of the rubber parts causes no protection against corrosion and in terms of its resilience is inferior to the composition according to Example 1,

The composition of the comparative example IA was also used in the front fork of a racing motorcycle and errors occurred, especially in the rubber seals and with regard to the abrasion of the upper brushes. In addition, corrosion occurs when water comes into contact with parts whose Chrome plating has been damaged.

«Π9808 / 0731

as part of

Other modifications / of the present invention include the substitution of dimethylpolysiloxane fluids having viscosities of 60 and 140 centistokes in place of the 100 centistokes of Example 1. A methylphenyl silicone oil having a viscosity of 200 centistokes and low in phenyl groups can also be used. A methylphenyl silicone oil with a viscosity of 300 centistokes and a high phenyl group content can also be used. Branched methyl silicone oils, branched methylphenyl silicone oils, branched chlorophenylmethyl silicone oils, fluorosilicone oils and nitrile silicone oils are also suitable.

Instead of the mixture of tributyl phosphate and dioctyl azelate as component (ii), each of the two compounds can also be used alone can be used. Tri (2-ethylhexyl) phosphate or triphenyl phosphate can also be used instead of tributyl phosphate will. Instead of dioctyl azelate, diisooctyl sebacate or dibenzyl succinate can be used.

In component (iii) can instead of the zinc diisopropyldithiophosphate Manganese diisopropyl dithiophosphate, zinc diisopropyl phosphate and zinc dimethyldithiophosphate can be used.

In component (iv), substituted zinc naphthenate can be used Copper naphthenate and magnesium octoate are used.

In addition to shock absorbers for motorcycles, the method according to the invention can also be used to dampen shocks in other systems, such as mechanisms that work with hydraulic pressure, Brake cylinders (called "dash pots" in English), vibration dampers, Artillery recoil mechanisms, door buffers and the like in which a liquid is used to control the relative To cause movement of a piston in an enclosing chamber,

Claims (23)

Claims Method of damping impacts caused by an assembly which comprises a movable part within an enclosing chamber and at least one rubber seal includes wherein pressures are imparted to the movable part by means of a hydraulically damping amount of a composition contained in the chamber, the composition being characterized by the following components: (i) a major portion of a liquid organopolysiloxane in which the organic radicals are selected from optionally halogen-substituted ones monovalent hydrocarbon radicals, cyanoalkyl radicals or mixtures of the aforementioned radicals which are 1 to 8 Contain carbon atoms and where at least some of the radicals are alkyl radicals with up to 3 carbon atoms, (ii) a minor proportion of a compound or a mixture of compounds which are compatible with component (i) and cause the rubber seal to swell considerably can and (iii) a small, effective amount of up to 15 wt -.% of the total weight of the composition of a compound which can increase the load capacity of a film formed from the component (i). 2. The method according to claim I _3, characterized in that the structural unit is a shock absorber which comprises an elongated metallic cylindrical pressure chamber and a metallic piston which is arranged movable to and fro therein and is connected to a piston rod which extends out of the chamber extends and wherein the rubber seal consists of natural rubber or synthetic diene rubber. <5O98O8 / G73 1 3. The method according to claim 2, characterized that the shock absorber is an element in a vehicle or motorcycle. 4. The method according to claim 2 or 3, characterized j that the shock absorber is an element in the front fork of a motorcycle or in the front fork of a Racing motorcycle is. 5. Process according to claims 1 to 4, characterized in that * the organic radicals of the Organopolysiloxane are monovalent hydrocarbon radicals having 1 to 8 carbon atoms. 6. The method according to claim 5, characterized in that the monovalent hydrocarbon radicals comprise alkyl radicals having 1 to 3 carbon atoms or phenyl radicals. 7. The method according to claims 1 to 6, characterized in that the organopolysiloxane the has the following formula: (CH) Si Si 0 -J-Si (CH where η is a number sufficient to give the liquid a Viscose Rent. Viscosity between 5 and 4000 centistokes at 25 ° C can be 8. The method according to claims 1 to 7, characterized in that component (ii) a small effective amount of up to 10 wt .- /? the overall composition which is selected from (a) a liquid organic phosphate in which the organic 609808/0731 2533879 see radicals are selected from optionally halogen-substituted monovalent ones Hydrocarbon radicals or mixtures thereof and the radicals contain 1 to 8 carbon atoms, (b) a liquid diester of an alcohol having 1 to 12 carbon atoms and a dicarboxylic acid having 4 to 12 carbon atoms or (c) Mixtures of (a) and (b). 9. The method according to claim 8, characterized in that component (a) is a trialkyl phosphate or is tributyl phosphate. 10. The method according to claim 8, characterized that component (b) is a dialkyl ester of a saturated aliphatic dicarboxylic acid. 11. The method according to claim 8, characterized that component (b) is dioctyl azelate. 12. The method according to claim 8, characterized in that it is marked that component (c) in essentially equal proportions by weight of tributyl phosphate and dioctyl azelate includes. 13. The method according to claims 1 to 12, characterized in that component (iii) is a Metal salt of phosphoric acid ester or thioester. 14. The method according to claim 13, characterized in that component (iii) is a copper, Magnesium, manganese, lead or zinc salt includes. 15. The method according to claim 14, characterized in that component (iii) zinc dialkyldithiophosphate is. 6098 ^ 8/0731 16. The method according to claim 15 , characterized in that component (iii) is zinc diisopropyldithiophosphate. 17. The method according to claim 2, characterized in that at least one of the metallic elements is prone to corrosion and the composition additionally contains a minor effective amount up to 10 wt -% of the total composition containing a corrosion inhibitor.. 18. The method according to claim 17 , characterized in that the component (iv) comprises a copper, magnesium, lead or zinc salt of an organic carboxylic acid having 4 to 16 carbon atoms. 19. The method according to claim 18, characterized that component (iv) comprises zinc naphthenate. 20. A method of damping shocks transmitted through an assembly that includes a moving part within a enclosing chamber and enclosing at least one rubber seal, the transmission of the prints to the movable Part takes place by means of a hydraulically damping amount of a composition contained in the chamber, characterized in that the composition comprises the following ingredients: (i) a liquid dimethylpolysiloxane Plüssigkeit having a viscosity of about 5 to about 1,000 centistokes at 25 ⁰ C, (ii) 0.5 to 5 wt .- # tributyl phosphate and 0.5 to 5 wt .- # dioctyl azelate, (iii) 0.5 to 15 wt. # zinc diisopropyl dithiophosphate and (iv) 0 to 5% by weight zinc naphthenate, all percentages being based on the total weight of the composition. 609808/0731 21. The method according to claim 2, characterized in that the composition has the following ingredients includes: (i) from 90 to 95 wt .- # a dimethylpolysiloxane fluid having a viscosity of 50 to 150 centistokes at 25 C, (ii) 2 to 5 wt .- $ of dibutyl phosphate and 2 to 5 wt -.% dioctyl azelate · j (iii) 0.5 to 10 wt. $ zinc diisopropyl dithiophosphate and (iv) 0.1 to 2.5 wt. $ zinc naphthenate, all percentages based on the total weight of the composition. 22. Composition, characterized by the following components: (i) a liquid dimethylpolysiloxane Plüssigkeit having a viscosity of about 5 to about 1,000 centistokes at 25 C, (ii) 0.5 to 5 wt -.% tributyl phosphate and 0.5 to 5 wt .- # dioctyl azelate, (iii) 0.5 to 15 wt -.% zinc diisopropyl dithiophosphate and (iv) 0 to 5 wt .-% zinc naphthenate, all percentages being based on the total weight of the composition. 23. Composition, characterized by the following components: (i) from 90 to 95 wt -.% of a DimethyIpοIysiIoxan fluid having a viscosity of 50 to 150 centistokes at 25 C, (ii) 2 to 5 wt .-% dibutyl and 2 to 5 wt .- / 2 dioctyl azelate, (iii) 0.5 to 10 wt -.% zinc diisopropyl dithiophosphate and (iv) 0.1 to 2.5 wt -.% zinc naphthenate, all percentages being based on the total weight of the composition is based. 60980 8/0731