SK146895A3 - 3,9-bis(methylbicyclo/2,2,1/hept-5-en-2-yl)-2,4,8,10- -tetraoxaspiro-/5,5/undecan, preparation method thereof and antiozonant on its base - Google Patents

Abstract

3,9-Bis(3-methylbicyclo[2,2,1]hept-5-en-2-yl)-2,4,8,10- -tetraoxaspiro[5,5]undecane of the general formula (I) is prepared by reaction of pentaerythriotol with 3-methylbicyclo- -[2,2,1]hept-5-en-2-carbaldehyde having a mole ratio 1 : 2 in at least one inert organic solvent medium in the presence of an acidic dehydrating catalyst at the boiling point of the solvent to be used or a mixture of solvents. It can be used as a non-colouring antiozonant for natural and/or synthetic caoutchoucs, individually or in combination with wax on bases of the micro-crystalline paraffin.

Description

Technical field

The invention relates to 3,9-bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane which represents a novel cyclic pentaerythritol bis-acetal, a process for its preparation and its use for the protection of vulcanizates based on natural and / or synthetic rubbers against the destructive action of atmospheric ozone without affecting their color and their undesired contact coloring.

BACKGROUND OF THE INVENTION

The condensation products of alcohols with aldehydes, commonly called acetals, represent a wide range of chemical compounds with various uses, not only the acetal alcohols but also the polyols acetals with the most diverse aldehydes are known. A relatively new field of application for some acetals is the protection of natural and / or synthetic rubbers against the destructive effects of atmospheric ozone. It is well known that vulcanized rubber products deteriorate in the presence of ozone due to tensile, compressive or bending stress due to the formation of cracks in their surface layer. The shelf life of these products can be greatly extended by adding relatively small amounts of some of the commercially available p-phenylenediamine derivatives, such as N-phenyl-N'-isopropyl-p-phenylenediamine, to the rubber mixture prior to vulcanization. A common disadvantage of p-phenylenediamine derivative-based antiozonants is that they are colored by the light and are therefore only applicable to carbon black vulcanizates. One possible solution to this problem is the use of the cyclic acetals of polyols and in particular the cyclic bis-acetals of pentaerythritol of the general formula I:

Ο - ch ₂ ch ^ -o

CH C \ Z \

O- ^CH 2 CH 2 -O

(D wherein R has the same or different meanings and represents hydrogen or methyl and n represents the integer 0 or 1 described in DE 25 48 911 A1. The most effective of these appears to be a derivative in which R represents hydrogen and n represents 0 / 3,9- bis (cyclohex-3-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane] This cyclic bis-acetal of pentaerythritol has also found commercial application especially in products based on polychloroprene rubber and its metallulcanizates DE 25 48 911 A1 also discloses mixtures of compounds of the formula I with waxes based on microcrystalline paraffins, which are known to form a compact film on statically stressed products providing a certain degree of protection against the destructive action of ozone, which however, it rapidly disrupts under dynamic or intermittent static / dynamic stress. Not only non-staining cyclic acetal-type antiozonants but also other agents relatively narrow Its range of known non-staining antiozonants in efficacy significantly lags behind anti-zonates based on p-phenylenedamine derivatives, providing scope for finding new, more efficient structures.

SUMMARY OF THE INVENTION

We have now developed 3,9-bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane of the structural formula:

FROM

CH \

o — ch ₂ ch ^ -ocz \ o — ch ₂ ch ^ o

which represents the cyclic bis-acetal of pentaerythritol with 3-methylbicyclo [2.2.1] hept-5-ene-2-carbaldehyde.

3,9-Bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane is prepared by reacting pentaerythritol with 3-methylbicyclo [2,2,1] hept-5-ene-2-carbaldehyde in a molar ratio of 1: 2 in at least one inert organic solvent and in the presence of an acidic dehydration catalyst at the boiling point of the solvent or solvent mixture used. The process can be carried out under an inert gas atmosphere. Polar (e.g. methanol, ethanol, dioxane) and non-polar (e.g. petrol, toluene) solvents are suitable as inert organic solvents for the process of the invention. When used with a water-immiscible solvent, the reaction water can be removed from the reaction medium by azeotropic distillation.

The acid dehydration catalyst used in the process according to the invention may be, for example, hydrochloric acid, zinc chloride, sulfuric acid, benzenesulfonic acid, naphthalenesulfonic acid or p-toluenesulfonic acid in an amount of 0.05 to 5.0, preferably 0.1 to 1.0 % by weight based on the starting (3-methylbicyclo [2.2.1] hept-5-ene-2-carbaldehyde).

We have subsequently found that 3,9-bis (3-methylbicyclo [2 _/ 2,1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane is a highly potent non-staining antiozonant. When homogeneously incorporated into mixtures based on natural and / or synthetic rubbers, their vulcanizates acquire a high degree of long-term resistance to ozone crack formation without undesirable color changes and contact coloring.

3,9-bis (3-Methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane is useful for protecting these elastomers against destructive destruction atmospheric ozone: polychloroprene, natural polyisoprene, other synthetic rubbers based on butadiene, dimethylbutadiene, isoprene and their homologs, copolymers of conjugated diolefins with vinyl group-containing monomers such as styrene, alpha-methylstyrene, methacrylonitrile, acrylonitrile, acrylonitrile based on ethylene, propylene and at least one unconjugated diene, for example dicyclopentadiene, 5-ethylidene-2-norbornene or

1,4-hexadiene. It is particularly suitable for polychloroprene alone and for combinations thereof with the abovementioned metallizable natural or synthetic rubbers in which the proportion of polychloroprene constitutes at least 20% by weight, preferably 30% by weight.

3,9-bis (3-Methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane is added to the rubber mixtures in an amount ensuring protecting their vulcanizates against the destructive action of atmospheric ozone, which is 0.05 to 10.0, preferably 0.5 to 5.0% by weight, based on the weight of the elastomer to be protected. The rubber mixture may be incorporated as such as a solid masterbatch or other conventional application form using dedicated equipment such as a two-roll calender, a kneading machine and others, ensuring perfect homogeneity of the mixture before, at the same time as, or as the last ingredient. Further components of such rubber compositions are, in particular, components of vulcanization systems, fillers, plasticizers, non-coloring antioxidants, blowing agents, pigments, flame retardants, or others, provided that they are soluble in the system and do not antagonize the anotizonant effects of the invention.

Rubber mixtures containing 3,9-bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane can be vulcanized at conventional temperatures, preferably 130-180 ° C, but temperatures outside this range are also suitable.

We have also found that the protective effect of 3,9-bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane surprisingly, against the destructive effect of atmospheric ozone on vulcanizates based on natural and / or synthetic rubbers, it is surprisingly significantly increased by the addition of 0.25 to 3 parts by weight of a mixed wax based on microcrystalline paraffins per 1 part by weight of an antiozonant.

The rubber compositions containing the antiozonant according to the invention can be processed into semi-finished or finished products such as various profiles and seals, cable sheaths, light tire and bicycle sidewalls, sports equipment, footwear and other technical rubber products which, in addition to degradation resistance It also requires color stability and no contact coloring.

The 3,9-bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane antiozonant according to the invention is unexpectedly characterized high efficiency against destructive action of atmospheric ozone on vulcanizates based on natural and / or synthetic rubbers both under static and dynamic conditions, low volatility and elution from vulcanizates, excellent dispersibility and tolerability in rubber mixtures and in these parameters significantly exceeds the known known antioxidants.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

13.62 g (0.1 mol) of pentaerythritol, 27.24 g (0.2 mol) of 3-methylbicyclo [2.2.1] hept-5-ene were charged to a 500 ml three-necked flask with azeotropic adapter and mechanical stirrer. -2-carbaldehyde, 150 cm ^{3 of} toluene and 0.2 g of p-toluenesulfonic acid, the mixture was heated to reflux temperature and kept under stirring for 6 h. The reaction water was collected in an azeotropic cap. Then the reaction mixture was cooled to 40-45 ° C, neutralized with aqueous sodium carbonate solution, after the aqueous phase was separated off, toluene was distilled off and 100 cm ^{3 of} 95% ethanol were added to the residue. The resulting mixture was refluxed until the melt crystallized. The suspension was allowed to cool to 10-15 ° C, the ethanol was aspirated, the filter cake was washed with 50 cm ^{3 of} ethanol, and the crystalline product was air dried. 33.15 g of 3,9-bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane was obtained with a temperature of mp 165-170 ° C, which represents a yield of 89%.

^PreC 23 ^H 30 ° 4 MW 370.50

H, 7.89; O, 16.73

Found: C, 75.19; H, 8.01; O, 16.80

Mass spectrum identification by GC-MS cation detection (E1):

MS: 66; 240; 306; 372nd

The same resulting product was also obtained when petrol instead of toluene was used alone or in a mixture with methanol or condensation was carried out without distilling the reaction water in methanol or cyclohexane-methanol. The process may also be conducted under an inert gas atmosphere.

Examples 2-7 of the invention illustrate the efficacy of an antiozonant based

3.9-Bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane according to the invention (AO1) against destructive action atmospheric ozone to natural and / or synthetic rubbers compared to commercially available

3,9-bis (cyclohex-3-en-2-yl) -2,4,8,10-tetraoxaspiro [5,5] undecane (hereinafter AO 2), as the most effective of the structurally closest non-staining antiozonants described in DE 25 48 911 Al. The proportions of the individual components in the rubber mixtures are given in parts by weight per 100 parts by weight of rubber (dsk). The ozone concentration in the atmosphere in which the samples were exposed is reported in pphm (number of parts of ozone per 100 million parts of air). Samples of the test vulcanizates were first allowed to relax for at least 24 h at the set deformation value in an ozone-free atmosphere and then exposed to the ozone atmosphere under static conditions. In all evaluations, a threshold strain value (PD) was used as the criterion for the destructive action of ozone, which is the highest value of the static tensile strain in% which does not yet contain ozone cracks on the test specimens after the prescribed exposure time. The symbol x in Tables 1 to 6 indicates the burst of the specimen. The wax used in the tests described in Examples 4 and 6 represents a commercially available mixture of n-paraffins and isoparaffins having a melting point of 66-70 ° C, a viscosity at 100 ° C of 6.5-8 mm ² , s ^-1 and a refractive index at 100 ° C, 1.428-1.431.

Example 2

Rubber blends of the following composition were prepared on a laboratory kneading machine:

polychloroprene, type WRT silica, surface area 140 m ² .g ^-1 carbon black N 220, type ISAF stearic acid zinc oxide magnesium oxide di- (butoxyethoxyethyl) adipate

Ethylene thiourea N-cyclohexyl-2-benzothiazolylsulfenamide

4,4 ' -dicmyldiophenylamine antiozonant

100

0.5 according to Tables 1 and 2

Trapezoidal test specimens with dimensions of 50/100 xi00x1 mm were prepared from these mixtures by pressing to the optimum at 155 ° C, which were evaluated according to STN 63 15 27, resp. ISO 1431/1 based on the vulcanizate resistance to the destructive action of ozone.

Test specimens were exposed under the following static conditions:

A: ozone concentration 200 pphm, deformation 31%, temperature 40 ° C B: ozone concentration 400 pphm, deformation 31%, temperature 40 ° C

The threshold deflection values under conditions A are given in Table 1 and in conditions B in Table 2.

Table 1

antiozonant [dsk] PD [%] exposure time [h] íil'fflie liífillll IISKIIIJ; 188 without antiozonant 11.3 7.4 x x x A01 1,0 > 31.0 > 31,0 > 31.0 > 31.0 30 AO2 1,0 30.7 16,8 - 10.1 x x

Table 2

antiozonant [dsk] PD [%] exposure time [h] without antiozonant 9.8 7.9 x AO 1 1.0 25 22.3 16.1 AO 2 1.0 13.2 11.3 x

Example 3

Rubber mixtures of the following composition [dsk] were prepared on a two-roll calender:

polychloroprene, type WRT 100 kaolin 100 titanium dioxide 5 silica, surface area 140 m ² .g ' ¹ 20 zinc oxide 5 magnesium oxide 5 naphthenic mineral oil 20 ethylene thiourea 1,2 antiozonant according to table 3

Next, the procedure was as in Example 2. The threshold deflection values are shown in Table 3.

Table 3

antiozonant [dsk] PD [%] exposure time [h] conditions conditions B . 70 10 llOll 96 without antiozonant 12.2 6.4 x 18.9 10.1 x x AO 1 0.5 > 31.0 > 31.0 24.3 > 31.0 > 31.0 > 31.0 29.7 1.5 > 31.0 > 31.0 > 31.0 > 31.0 > 31.0 > 31.0 > 31.0 AO 2 0.5 24.7 16.9 x 25.3 19.8 10.4 x 1.5 > 31.0 23.2 x > 31,0 > 31,0 25.7 13.6

Example 4

Mixtures of the following composition [dsk] were prepared on a kneading machine:

butadiene-styrene rubber, type SBR 1500 100 carbon black N 330, type HAF 50 zinc oxide 3 stearic acid 1 sulfur 1,75

N-cyclohexyl-2-benzothiazolylsulfenamide 1 antiozonant according to Table 4 wax according to Table 4

Trapezoidal test specimens were prepared by vulcanizing the mixture by compression molding at a temperature of 150 ° C and exposed under the following conditions: ozone concentration of 100 pphm, deformation 31%, temperature of 32 ° C.

Table 4

antiozonant [dsk] PD [%] exposure time [h] 4 lllllWIBij-i 48 without antiozonant 17.3 9.8 4.1 x wax 2 > 31,0 22.5 15.3 9.5 AO 1 4 27.6 16.9 10.2 x AO 2 4 22.3 Π 7.8 x AO 1 + wax 4 + 2 > 31,0 > 31,0 25 21.5 AO 2 + wax 4 + 2 > 31,0 25.6 17.1 12

Example 5

Rubber blends of the following composition were prepared on a laboratory kneading machine:

natural rubber, type white crepe 100 zinc oxide 10 white filler, type blane - fix 60 titanium dioxide 10 stearic acid 1

N-cyclohexyl-2-benzothiazolylsulfenamide 0.5 antiozonant according to Table 5 wax according to Table 5

Trapezoidal test specimens were prepared by compression molding at 145 ° C and exposed to the following conditions:

C: ozone concentration 50 pphm, deformation 13%, temperature 32 ° C

D: ozone concentration 100 pphm, deformation 13%, temperature 32 ° C

The threshold deflection values are shown in Table 5.

Table 5 t-

antiozonant [dsk] exposure time [h] conditions C conditions D 48 • '-, 24:' ' 192 without antiozonant 5.2 4.6 4.6 3 x wax 4 > 13.0 > 13.0 > 13.0 9.3 x AO 1 4 > 13.0 11.1 12.4 8 x AO 1 + wax 4 + 4 > 13.0 > 13.0 > 13.0 > 13.0 > 13.0 AO 2 4 > 13.0 8.4 11.1 6.7 x AO 2 + wax 4 + 4 > 13.0 > 13.0 > 13.0 > 13.0 10.2

Example 6

Rubber blends of the following composition [dsk] were prepared on a kneading machine:

butadiene-styrene rubber, type SBR 1502 40 natural rubber, type SMR - 5L 60 silicon dioxide, surface area 210 mil ¹ 20 magnesium carbonate 30 titanium dioxide 15 zinc oxide 5 kaolin coumaronic resin stearic acid

Tributylthiourea sulfur 2,2'-dibenzothiazolyldisulfide

2,6-di-tert. b u ty l-4-methylphenol antiozonant wax

1.2

2.2

1.5 according to Table 6 according to Table 6

Test trapezoidal bodies were prepared by vulcanizing the mixture by compression at 150 ° C and exposed under the following conditions:

E: ozone concentration 50 pphm, deformation 31%, temperature 40 ° C F: ozone concentration 100 pphm, deformation 31%, temperature 27 ° C

The threshold deflection values are shown in Table 6.

Table 6

antiozonant [dsk] PD [%] exposure time [h] conditions Conditions F illlWieftll ijjiiiäSHiiiiiií llllSIIIl 24 without antiozonant 12.6 7.9 5.2 17.7 13.2 8.8 wax 2 24.1 19.6 12.2 30.3 26 17.4 AO 1 4 16.8 10.3 7.2 23.7 18 12 AO 2 4 15.2 9.5 7.2 20.2 16.6 10.5 AO 1 + wax 4 + 2 30 28.8 24 31 29.6 26.7 AO 2 + wax 4 + 2 27.2 23.1 17.1 31 28 22.9

The effect of the antiozonant of the invention (AO 1) on the coloring of the vulcanizate of the rubber composition of Example 6 compared to the known antiozonant (AO 2) was assessed based on its whiteness after exposure to UV radiation (source - silicon lamp) and evaluated using a MOMCOLOR color meter based on the parameter

E (total chromatographic change). The values are shown in Table 7.

Table 7

Example 7

oztíozozon d [dsk] E exposure time melt . '.', ¾ ^: 12  24 without antiozonant 0 8.89 10 AO 1 4 0 9.24 9.4 AO 2 4 0 9.34 9.65

The results summarized in Tables 1 to 7 demonstrate the high effectiveness of the inventive antiozonant (AO 1) against the destructive action of a wide range of concentrations (50-400 pphm) of ozone on various types of rubbers without undesirable contact coloring, not only at normal but also at elevated temperatures. the application of real deformations (13 to 31%) of the vulcanizate is significantly higher than the efficacy of the structurally closest known antioxidant (AO 2) even at low dosage levels where high relative molecular weight is a disadvantage. Thanks to this high efficiency, the surface of the vulcanizates remains virtually intact by ozone cracks even at long exposure times, while the efficacy of the known antiozonant (AO 2) is lost quite rapidly even at higher dosing levels, causing the vulcanizate to degrade gradually as ozone cracks develop. his destruction.

Claims (8)

PATENT CLAIMS 1) 3,9-bis (3-Methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5.5] formula: FROM \ The CH CH FROM CH-O 2) A process for the preparation of 3,9-bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10-tetraoxaspiro [5.5] iundecane as defined in claim 1 characterized in that pentaerythritol is reacted with 3-methylbicyclo [2.2.1] hept-5-ene-2-carbaldehyde in a molar ratio of 1: 2 in the environment of at least one inert organic solvent and in the presence of an acidic dehydration catalyst at a temperature boiling of the solvent or solvents used. ·% 3. The process of claim 1 wherein the acidic dehydration catalyst is selected from the group consisting of hydrochloric acid, zinc chloride, sulfuric acid, benzenesulfonic acid, naphthalenesulfonic acid, or p-toluenesulfonic acid, and is used in an amount of 0.05 to 0. 5% by weight, based on the starting 3-methylbicyclo [2.2.1] hept-5-ene-2-carbaldehyde, 4) Antiozonant for natural and / or synthetic rubbers characterized by satin consisting of 3,9-bis (3-methylbicyclo [2.2.1] hept-5-en-2-yl) -2,4,8,10 - Tetraoxaspiro [5,5] undecane as defined in claim 1. 5) A method for stabilizing natural and / or synthetic rubbers against the destructive action of ozone by adding an antiozonant, characterized in that the antiozonant according to claim 4 is used in an amount of 0.05 to 10.0% by weight, based on the weight of the elastomer to be protected. The process according to claim 5, characterized in that 0.25 to 3.0 parts by weight of wax are added per part by weight of the antiozonant. 7) Basis composition. natural and / or synthetic rubbers, characterized in that it comprises; The antiozonant of claim 4 in an amount of 0.05 to 10.0 wt.% based on the weight of the elastomer to be protected. . A composition according to claim 7, characterized in that it contains 0.25 to 3.0 parts by weight of wax per mono-mass part of the antiozonant.