HU202896B - Process for producing soft and/or white or coloured and/or foamed rubber and polyolefin products by vulcanization in microwave field - Google Patents

Abstract

To 100 pts.wt. of rubber and polyolefin compsns., 1-100 pts.wt. conveniently 5-50, pref. 10-20 pts.wt. of a dielectric heating promoter is added for the microwave curing of soft (over 20 deg. shore) and/or white or coloured, or cellular (over 0.1 g ml density) rubber and polyolefin articles.

Description

The present invention provides a process for vulcanization in microwave space to soft and / or white and / or white. for the production of colored and / or foamed rubber and polyolefin products.

It is well known that in high frequency (20-100 MHz) and ultra high frequency (UHF) or microwave (100-10,000 MHz) fields, only materials with adequate dielectric loss due to their polarity heat up.

In the rubber and, more rarely, in the plastics industry, microwave space is used to mix or polish rubbers with suitable polarity-enhancing additives. to heat certain polyolefin mixtures to a temperature at which they cure or cure. This principle is also used for continuous operation extruder lines which cure in a microwave space, where the profile leaving the steam-driven extruder through a given pulley is heated in the microwave space at 2.45 GHz to the temperature of the vulcanization and then subjected to suitable heat retention and cooling.

The extremely disadvantage of this vulcanization technology is that it can only be applied to mixtures which have a significant heating effect. The requirement for microwave warming is that the product is the product of the permittivity (ε ') and the dielectric loss coefficient (tg 6), the so-called microspheres. loss number (ε '· tgó - ε') should be about 0.2 or greater. (Encyclopedia of Polymer Science and Technology, Vol. 5, Wiley-Interscience, N.Y. 1966, pp. 6-7.) Apolar rubbers such as e.g. natural rubber (NR), styrene / butadiene-based rubbers (SBR), ethylene / propylene co- or ethylene / propylene / diene terpolymer rubbers (EPM or EPR or EPDM), butyl rubbers (IIR), silicone rubbers (Si) and polyisoprene (IR) do not. There are basically three ways to help this:

- the introduction of polar fillers and reinforcing materials,

- by polar small-molecule mixing,

- by the addition of polar small molecule compounds.

The best known representatives of reinforcing and filler materials are various grades of carbon black and SiO2 (white carbon black). The heat generated by the various types of carbon black is reduced in the following order:

HAF> EPC> FEF> SRF> MT

Since apolar rubbers, respectively. warming of bulk mixtures of apolar rubber with high activity and relatively low carbon hardness products bound to the presence of relatively high amounts of carbon black. Of course, the same statement applies to perfectly apolar polyolefins. The addition of relatively high amounts of white fillers (kaolin, chalk, dolomite, S1O2) does not achieve the continuous heat of vulcanization.

The soft as well as white or white. Thus, formulations for the production of colored products necessarily contain polar polymers, oligomers and small molecule polar compounds. To the former group a

PVC, phenol / formaldehyde resin (PF), melamine / formaldehyde resin (MF), factic, ethylene / vinyl acetate (E / VAC), chlorinated polyethylene (CPE), poly (alkylene glycols) and their esters (3). (US Patent Publication No. 032 0228), while the latter deserves recognition as alkanolamines (Publication No. 3,032,028), small molecule nitrile compounds (European Patent Publication No. 23,675). Of course, formulas contain multiple polarity-enhancing ingredients at the same time. so e.g. No. 3,032,028. The disclosure document of the Federal Republic of Germany discloses poly (alkylene glycols) and their esters, alkanolamines, possibly S1O2, which results in a thermoplastic elastomeric product which is disclosed in U.S. Pat. and the Japanese disclosure discloses E / VAC, FeO, polyethylene glycol, triethanolamine and SiO2. In practice, very often, polar rubbers or other polar polymers are forced to be incorporated into the blend, which causes compatibility problems, significantly reducing the life of the product. If they do not use these polymeric additives, they will opt for the active S1O2 and / or other small molecule additives listed above, which will either result in an excessive hardness of the product or a worsening of the physical-mechanical properties of the mixture.

White or white for the production of colored and foamed rubber and polyolefin products, because of the proper sequentiality of the foaming and curing processes simultaneous operation, which is extremely difficult in microwave space. Foamed thermoplastic elastomeric products have been successfully prepared in UHF space using polar propellants (sulfohydrazides) in addition to standard polarity-enhancing additives (U.S. Pat. No. 4,352,854). For the introduction of the UHF space-heating and thus decomposing blowing agent, similar peroxy compounds (e.g., tert-butyl perbenzoate, GD 154 706; tert-butyl peroxy-γ-valerolactone, GD 3 018 321), are mainly used for crosslinking polyethylene (PE) in UHF space. White or white manufacture of colored and / or foamed UHF cross-linked products - especially for low-density foams

- unsolved.

Summarizing the current state of the art, it can be concluded that a filler with inactive properties which is not known

- mixtures of rubber or rubber; increase the dielectric heating of polyolefins without impairing the physical-mechanical properties of the vulcanized product,

- universally applicable in all apolar rubbers and polyolefins,

- favor the order of foaming and curing,

- white or white. colored products could also be produced.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above-mentioned drawbacks by

EN 202 896 Β spatially vulcanized soft and / or colored, respectively. suitable for the production of white and / or foamed rubber and polyolefin products.

It is a further object of the present invention to provide sufficient dielectric heating of rubber and / or polyolefin blends by introducing cheap, readily available domestic additives which do not impair the physical-mechanical properties of the product.

It has now been found that if the usual composition of non-polar rubbers for vulcanization in the microwave field is used. If zeolite and / or alumina are added to mixtures containing polyolefins, the mixture may be heated to the crosslinking temperature. Due to the high dielectric heating of these materials, the amount of carbon black required in the conventional formulation and other polarity-enhancing polymers, oligomers and small molecules can be reduced and thus soft and / or white or white. colored and / or foamed products can be manufactured.

A further basis of the invention is the discovery that the physical and mechanical properties of the rubber cured in the microwave space and of the crosslinked polyolefins are not altered when the above-mentioned residues are introduced, i.e. the additives act as inactive fillers.

Finally, the present invention is based on the discovery that dielectric heating additives improve the weather and heat resistance of polyolefins.

These findings are surprising to the person skilled in the art because the ε "value of the zeolite in the GHz frequency range is about 0.05 (D.W.Breck: Zeolite Molecular Sieves, Wiley-Interscience, 1974, pp. 392-397), so no heating effect is expected at all. There is no literature reference for such an effect of alumina.

It is also surprising that a well-vulcanized rubber is obtained even when using natural zeolite, which contains heavy metals which are known to be harmful (e.g., Mn, Co) and catalysts for the decomposition of plastic materials (eg, Cu).

A further surprising feature of the present invention is that the above dielectric heat-enhancing additives can be used in all rubber mixtures and, in their presence, reduce the risk of burns.

Finally, it is a surprising element of the present invention that the above additives do not adversely affect the foaming and curing processes and increase the heat resistance and weather resistance of the polyolefins. It would be expected that the decomposition of the blowing agent would be increased by the presence of the metal ions contained therein and, in the case of polyolefins, catalyzed by O2 absorption.

Accordingly, the present invention provides a process for the preparation of soft and / or white or colored and / or foamed rubber or polyolefin products by microwave vulcanization, characterized in that the rubber or polyolefin mixture of known composition is dielectric heated in addition to the usual constituents. as an excipient, zeolite and / or alumina is added in an amount of from 1 to 100, preferably from 5 to 50, preferably from 10 to 20, weight per unit weight of the polymer.

The process according to the invention is carried out by preparing the mixtures of rubber and polyolefin in a conventional manner, in which the above-mentioned dielectric heating additives are introduced together with the other powder additives. The finished mixture is then cured in the microwave space or continuously in the form of profile strips, or the preformed product is cured in a microwave oven in a batch mode.

The main advantages of the process according to the invention are as follows:

- it can produce soft (more than 20 Shore A hardness) and / or white and colored and / or foamed (greater than 0.1 g / cm ³ ) rubber and polyolefin products;

- dielectric heating enhancers are inexpensive, readily available;

- expensive dielectric fillers can be replaced or reduced by dielectric heating enhancers without compromising product quality;

- the addition of dielectric warming agents to form micellar vulcanizable mixtures of pure apolar rubbers;

- the process reduces the risk of burns to the blends, which is a necessary inherent of UHF blends containing polar polymer, oligomer and small molecule compounds, and can reduce the risk of vulcanization and control foaming;

- difficulties due to the presence of wet components due to the water-absorbing capacity of the dielectric heating additives;

- by the appropriate choice of additives, the decomposition of the blowing agent can be adjusted over a wide range of temperatures and thus the order of the process of foaming and curing can be ensured;

- Due to the light stabilizer and antioxidant effect of dielectric warming additives in polyolefin blends, a considerable amount of such additives can be saved.

The following examples illustrate the process of the invention in more detail.

Example 1

The black, very soft EPDM-based profile was manufactured on a UHF (2.45 GHz) UHF (2.45 GHz) machine with a 90 mm screw diameter, Troester, and was manufactured using the following conditions and formula. Processing Conditions: Each zone has a magnetron power of 60% and a temperature of 180-190-180 'C. And the recipe is as follows:

120 parts by weight (hereinafter te) EPDM (Dutral Square 537 / E2, manufactured by Montepolimeri) containing 50% by weight of oil te EPDM (Dutal Square 334, manufactured by Montepolimer)

HU 202 896 Β te ZnO te stearic acid poly (ethylene glycol)

100 you FEF carbon black you natural zeolite

100 te paraffin oil te CaO

0.75 te Tetramethylthiuram disulfide (TMTDS)

1.5 te 2-mercapto-benzothiazole (hereinafter MBT)

0.75 te tellur-diethyldithiocarbamate

0.75 te zinc dimethyldithiocarbamate (ZDMC)

0.75 te dipentamethylene thiuram tetrasulfide

1.5 te sulfur

The vulcanized rubber profile has the following characteristics, respectively: tensile strength> 10 MPa, elongation at break> 550%, EIO-1.1 MPa, E300-4.4 MPa, tensile strength 16.5 kN / m, Shore A hardness 30. mechanical properties without using zeolite, the formulation had to be modified as follows:

130 te FEF carbon black te CaCO3

125 te paraffin oil te CaO

Despite the above recipe change, the magnetron power had to be increased by 15-20% in each zone and the temperature in the middle section of the heat-retaining tunnel had to be raised to 200 ° C. The product obtained had the same physical-mechanical characteristics as Example 1, but had a hardness of 37 Shore A. Monsanto's rheometer data at 180 ° C for the mixture of Example 1 is t-2-1'18 ", t-90-3'05", and for the zeolite-free reference sample is t-2-1'09 ", t- 90-3'10 ".

Example 2

A white profile strip was prepared on the Troester apparatus mentioned in Example 1 according to the following formula:

125 te EPDM (Dutral Square 235 / E2, manufactured by Montepolimer) te low density polyethylene (Tipolen FA 2210, produced by the Tisza Chemical Plant) te ZnO te stearic acid teO2D-nitrile te NaA molecular sieve te γ-Αΐ2θ3 (K-10, Almásfüzitő

Aluminum Factory Product) te aluminum oxide hydroxide

120 te collagen surface treated colloidal S1O2 te poly (ethylene glycol) te make-up silane te perraffin oil te CaO water binder

1.5 te MBT

1.5 te ZDMC te dipentamethylene thiurane tetrasulfide

0.5 te ethylene thiourea (2-mecaptoimidazoline) 2 te sulfur

Mixture characteristics: ML (1 + 4) 100 'C - 32, Monsanto t-2-40 ", t- 90-2'56". Physical and mechanical properties of UFH vulcanized rubber: tensile strength>

7.5 MPa, elongation at break> 300% EIO-4.3 MPa, E200-5.9 MPa, residual deformation after compression (22 h, 70 'C) 10% and 100% elongation 5%, Shore Hardness 65. During vulcanization, the performance of the netrons was 60-60-50-50% and the temperature of the heat-holding section was 170-180170 ° C. If the above physico-mechanical properties were achieved without dielectric warming additives, the amount of colloidal S1O2 had to be increased to 240 te, resulting in an increase in hardness to 73 Shore A. In the latter comparative mixture, the power of the magnetrons in the first two zones had to be raised to 70-70% and the temperature of the heat-holding section was uniformly raised to 180 ° C.

Example 3

In each case, the procedure described in Example 2 was followed. However, only 1 te was used in the formulation, instead of 10 te Ti 2, and 5 te chromium oxide green pigment was added. The resulting green propfil had a hardness of 64 Shore A.

Example 4

A microcellular foam rubber profile was prepared on the Troester apparatus described in Example 1 using the following formula:

125 te EPDM (same as Example 2) te ZnO te stearic acid

120 te natural zeolite (clinoptilolite content 40% and mordenite content 20% by weight) te T1O2 te iron oxide red pigment 0.5 te organic red azo dye

1.5 te mercapto-silane te azodicarbonamide (Evipor, United Chemical Works)

1.9 Te ethylene thiourea (2 mercaptoimidazoline)

1.2 te dipentamethylene thiuram tetrasulfide te zinc dibutyl dithiocarbamate

2.5 te zinc diethyl dithiocarbamate

1.5 te TMTDS

1.3 te MBT te CaO

1,3 te sulfur

The mixture has the following characteristics: ML (l + 4) 100 'C-23, Monsanto t-2 200' C at 37 'and t-90 value Γ35'. The density of the foam material is 0.3 g / cm ^{2 3} and is completely closed cell since there is no water uptake. Its residual deformation is 70% after a heat treatment of 50% after compression (70 h, 70 'C), read 30'. If the formula contained the same colloidal silica gel S1O2 instead of 120 te zeolite and 4 te azodicarbonyl-41 as the propellant

EN 202 896 Β and 5 te more polar p, p'-oxybis (benzenesulfonyl) hydrazide, the mixture had the following characteristics: ML (1 + 4) 100 'C-27, Monsanto t-2 At 200 'C it was 33 "and t-90 was Γ40". The density of the foam produced was 0.32 g / cm, with a water uptake of 0.5% and a permanent deformation of 79%.

Example 5

A microcellular black foam material was prepared in Example 1 using the following formula:

te EPDM (same as Example 2) te IIR (BK-1045, Soviet type) te SBR (DSM ARKP / N, soviet type) te ZnO te stearic acid te SRF carbon black te γ-Αΐ2θ3 (Κ-330, product of the Apple Factory) you ZnY molecular sieve you Zn X molecular sieve

1.5 te mecapto-silane te paraffin oil te azodicarbonamide (identical to Example 4)

1.6 te ethylene thiourea (2-mercaptoimidazoline)

1.2 te dipentamethylene thiuram terosulfide te TMTDS

1.3 te MBT te CaO

1,3 te sulfur q

The resulting foam material had a density of 0.31 g / cm, a water uptake of 0 and a residual deformation of 40% under the conditions mentioned in Example 4. When producing foam material with similar properties without dielectric heating enhancers, half of the SRF carbon black had to be replaced by a more active FEF carbon black and 110 te colloidal silica gel was used instead of the same as described in Example 4. amount had to be increased to a total of 10 t, but half of it had to be given by a sulfohydrazide derivative. The reference sample thus prepared has the following characteristics: 0.36 g / cm ³ , 0.5% and 53% respectively.

Example 6

A microporous crosslinked polyolefin foam was prepared on the Troester apparatus described in Example 1 using the following formula:

you low density polyethylene (same as example 2) you polypropylene copolymer (Tipplen K 523,

Tisza Chemical Plant Product) te IR (Cárom 2200, Romanian type) te E / VAC (vinyl acetate content 28% by weight) te-y-AhO3 (K 330 type, product of Apple Tree Factory) te natural zeolite (same as Example 4) You are a paraffin oil

2.5 te 1,3-bis (tert-butyl peroxyisopropyl) benzene te ZnO te zinc stearate

3.5 te azodicarbonamide 'q

The resulting foam had a density of 0.12 g / cm, a tensile strength of> 1.4 MPa and a gel ratio of 62%. When CaC0 3 was used instead of dielectric warming additives, neither cross-linking nor significant foaming occurred; when using colloidal silica gel, the foam had a density of 0.25 g / cm ³ and a gel fraction below 10%. The density and cross-linking of the product of Example 6 could only be approached if the azodicarbonamide was replaced by a sulfohydrazide derivative and the peroxide was also replaced by butyl 4,4'-bis (tert-butyl peroxy) valerate. If the natural zeolite of Example 6 was mixed in an air-humid state instead of being leached, it would be able to reduce the amount of AI2O3 to 20 t by its excretion.

Example 7

On a UHF unit with 4 "6" magnetrons each equipped with a 120 mm worm diameter, Troester made a profile tape based on the following formula:

31.75% SBR (USSR 30 ARKM-15, Soviet type)

12.07% SBR (USSR 30 ARKP / N, Soviet type)

8.38% NR

1.30% TMTDS

1.55% N-cyclohexylbenzthiazole sulfenamide

0.15% sulfur

0.10% ethylene thiourea (2-mercaptoimidazoline)

4.60% CaO

0.50% β-phenyl-naphthylamine

0.70% N-isopropyl-N'-phenyl-p-phenylene diamine

0.50% stearic acid

1.50% ozone-depleting paraffin wax

1.50% bowing gum

4.90% extraction oil

0.40% N-cyclohexylthiophthalimide

20.70% FEF carbon black

7.01% (Na, Zn) type A molecular sieve

2.39% ZnO

During processing, the temperature of the 2x8 m long heat section had to be set to 180-190 'C and the 6 m cooling section could be operated. The product obtained complied with the requirements of DIN 4060 having a tensile strength> 10 MPa, a tensile elongation above 350% and a residual deformation below 15%. If FEF carbon black was used instead of the molecular sieve, during the processing the temperature of the heat-holding zone had to be raised to 200-220 ° C and the cooling section could not receive cooling water to ensure sufficient crosslinking. The residual deformation of the product (22 h, 70 'C) still did not meet the requirements, since its numerical value varied between 20 and 27%.

HU 202 896 Β

Example 8

Black 65 Shore A grade hardness EPDM-based profile strip was manufactured on a Troester UHF (similar to Example 7) using the following recipe:

100 te EPDM (Dutral Square 038 Ep, product of Montepolimeri) te accelerator mixture Deovulc EG3, product of DOG te diphenylguanidine

1.9 te sulfur te atactic polypropylene (Tipplen APP-C, product of the Tisza Chemical Plant) te stearic acid

100 te paraffin oil

14.5 te CaO paste (active ingredient content by weight)

138 you FEF soot you natural zeolite bag grits you ZnO

Physical-mechanical characteristics of the vulcanized profile strip: 65 Shore A hardness, 10 MPa tensile strength, 600% elongation at break. The extruder has a rotation speed of 50 min ' ¹ , a stripping speed of 6 m / min, magnetron power of 55-55-55-55%, and temperature of the heat sections 190 ° C.

When the zeolite was removed from the mixture, the power of the netron had to be increased to 65% and similarly the temperature of the heat-holding sections had to be raised to 210 ° C. These changes increase the risk of the profile tape becoming spongy and cause slight reversion and deburring on the surface.

Example 9

White Shore 70 Shore A Hard Based Ski Line Made on UFH Apparatus (Same as Example 1) with the following recipe:

100 te Ski Gum (Wacker R 411/60 Ci, Dicumyl Peroxide-containing Ski Gum Mixture, manufactured by Wacker) te Natural Zeolite Mill (identical to Example 4)

Physical-mechanical characteristics of the vulcanized cord: hardness 70 Shore A, tensile strength 5 MPa, elongation at break 270%. During processing, the extruder has a screw speed of 70 min ¹ and a pull-off speed of 4 m / min. The power of a megnetron is 70-70% 60-60%. The temperature of the heat-holding sections is 260'C. Significantly reduced by 40 wt. except for the zeolite from the mixture, the cord does not vulcanize.

Example 10

Black 50 Shore A hardness IR + SBR based profile strip was manufactured on the UHF apparatus of Example 1 according to the following formula:

te 1,4-cis-polyisoprene (SZKI-3, Soviet type) te SBR (product of Buna SB 152, Hüls) te sulfur

Thy 1.2 N-cyclohexyl benzothiazyl disulfide β-phenyl-naphthylamine te te stearic acid 0.6 N-cyclohexylthio-phthalimide 10 CaO paste you're you factice aromatic paraffin plasticizer you're you ZnO γ-Α1 ₂ 03 (same as with example 5) you SRF age you FEF age

Physical-mechanical properties of the vulcanized profile strip: 50 Shore A hardness, 7 MPa tensile strength, 400% elongation at break. The extruder has a rotation speed of 55 min- ¹ and a pull-out speed of 7 m / min. Magnetrons power: 70-70% -60-60%, temperature of the heat-holding sections 190 'C.

Excluding Al ₂ O _{3 from} the blend, the carbon black charge should be increased or the peeling rate slowed down, since raising the temperature of the heat-holding sections would cause degradation and reversal due to the presence of IR rubber.

Example 11

NBR + NBR / PVC-based Black 75 Shore A hardness profile strip was manufactured on the UHF apparatus of Example 1 according to the following formula:

te NBR / PVC (Buna NB 198, manufactured by Schkopau, GDR) te NBR (Buna NB 196, identical)

0.6 te tetramethylthiuram monosulfide

1.2 te sulfenamide type accelerator (Santocure MOR, product of Monsanto)

2.3 you sulfur

0.7 te N-cyclohexylthiophthalimide

0.4 te diphenyl guanidine

1,5 te stearic acid te diisoctyl phthalate (Eviplast 81, United Chemical Works) te dolomite te kaolin te dispersant active SiO ₂

1,5 te ethylene glycol te ZnO te instrument oil te SRF carbon black te natural zeolite mineral te faujazite type artificial molecular sieve

Physical-mechanical properties of the vulcanized profile strip: 75 Shore A hardness, 6 MPa tensile strength, 250% elongation at break. The extruder has a rotation speed of 45 min ' ¹ and a pull-off speed of 4 m / min. The power of a megnetron is 70-70-70-70%. The temperature of the heat-holding sections is 200'C.

Except for the zeolite in the mixture, the amount of carbon black should be increased to improve polarity, which is not a feasible option for this product due to the risk of carbon black extraction. Although its PVC content is fast-61

EN 202 896 Β requires warming up, rapid vulcanization as otherwise the PVC will soften under the influence of heat and thus the shape and frame retention essential for strip production will deteriorate.

If a mixture prepared from the above recipe is made by extrusion into a suitable preform - which may also be crosslinked and then cured or vulcanized. placed in the microwave to complete the vulcanization, the above physical-mechanical properties can be adjusted or adjusted depending on the degree of foreground curing. lightly spongy rubber products can be obtained from the non-crosslinked form.

All. Exemplary blend has improved aging and oil resistance, including acid oils, since its oil resistance is 100 K at 100 ° C according to ASTM D 2000-SAE J 200. Conversely, the reference sample not containing zeolite is classified in G.

Claims (3)

PATIENT INDIVIDUAL POINTS 1. A method of vulcanizing in a microwave space for the production of soft and / or white or colored and / or foamed rubber or polyolefin products, which is a dielectric warming additive for a mixture of rubber or polyolefin of known composition per 100 parts by weight of the polymer. Zeolite and / or aluminum oxide are added to 1-100, preferably 5-50, preferably 10-20. 2. The method of claim 1, wherein said zeolite is natural and / or artificial. Method according to claim 1 or 2, characterized in that a dielectric warming additive having a particle size of less than 150 μτη is used.