The new micronized talcs: new functions for extrusion and molding applications.The new micronized talcs provide compounders with a unique combination of characteristics in the field of semi-reinforcing mineral fillers for extruded and molded parts. Their lamellar structure Lamellar structures or microstructures are composed of fine, alternating layers of different materials in the form of lamellae. They are often observed in cases where a phase transformation front moves quickly, leaving behind two solid products, as in rapid cooling of acts as an internal lubricant Lubricant A gas, liquid, or solid used to prevent contact of parts in relative motion, and thereby reduce friction and wear. In many machines, cooling by the lubricant is equally important. and enables relatively low viscosities to be attained even at high loading levels and with low plasticizer plas·ti·ciz·er n. Any of various substances added to plastics or other materials to make or keep them soft or pliable. plasticizer or -ciser Noun content. The processability of micronized products is perfectly suited to the extrusion of profiles and molding of components, in that they give high outputs combined with very little wear of metal parts due to their non abrasivity. The level of reinforcement obtained with these new talcs attests to the excellent chemical compatibility between filler fill·er 1 n. One that fills, as: a. Something added to augment weight or size or fill space. b. A composition, especially a semisolid that hardens on drying, used to fill pores, cracks, or holes in wood, plaster, and elastomer elastomer (ĭlăs`təmər), substance having to some extent the elastic properties of natural rubber. The term is sometimes used technically to distinguish synthetic rubbers and rubberlike plastics from natural rubber. . Moreover, with an appropriate surface treatment, very high levels of compression and elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. resistance can be obtained. Lastly, the combination of high loading, low plasticizer content and the outstanding impermeability im·per·me·a·ble adj. Impossible to permeate: an impermeable membrane; an impermeable border. im·per of these micronized talcs stops the plasticizer and the vulcanization vulcanization (vŭl'kənəzā`shən), treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold. by-products from migrating to the surface of the parts, thereby reducing iridescent ir·i·des·cent adj. 1. Producing a display of lustrous, rainbowlike colors: an iridescent oil slick; iridescent plumage. 2. bloom of seals in car bodywork bodywork /body·work/ (-wurk?) a general term for therapeutic methods that center on the body for the promotion of physical health and emotional and spiritual well-being, including massage, various systems of touch and manipulation, caused by weathering. Micronized talcs: Excellent internal lubricants lubricants preparations for the lubrication of passages to reduce frictional injury, e.g. oily preparations, including petroleum jelly, lanolin or water-soluble preparations such as methyl cellulose. The main characteristics of talc are softness, lamellarity, inertness in·ert adj. 1. Unable to move or act. 2. Sluggish in action or motion; lethargic. See Synonyms at inactive. 3. Chemistry Not readily reactive with other elements; forming few or no chemical compounds. and hydrophobicity hy·dro·pho·bic adj. 1. Repelling, tending not to combine with, or incapable of dissolving in water. 2. Of or exhibiting hydrophobia. hy . It is the lamellar lamellar /la·mel·lar/ (lah-mel´ar) 1. pertaining to or resembling lamellae. 2. lamellated (1). lamellar pertaining to or emanating from lamella. crystalline Like a crystal. It implies a uniform structure of molecules in all dimensions. For example, phase change technology, widely used for rewritable optical discs, uses crystalline spots (bits) to reflect the laser beam. Amorphous, non-crystalline bits do not reflect light. structure which provides the distinctive rheological rhe·ol·o·gy n. The study of the deformation and flow of matter. rhe  o·log properties of rubber
compounds containing talc.The viscosity of these compounds is appreciably ap·pre·cia·ble adj. Possible to estimate, measure, or perceive: appreciable changes in temperature. See Synonyms at perceptible. lower than that obtained with other mineral fillers. Figure 2 shows the different Mooney viscosities of EPDM EPDM Ethylene-Propylene-Diene-Monomer EPDM Enterprise Product Data Management EPDM Ethylene Propylene Dimonomer (industrial/commercial piping/plumbing components) EPDM Engineering Product Data Management compounds containing only mineral fillers at equivalent loading levels. Viscosity may be reduced by 35% with this micronized talc compared with other mineral fillers. Excellent filler-elastomer compatibility The chemical nature of talc gives it an organophilic character which makes it highly compatible with polymers. The reinforcement obtained with micronized talc can, therefore, be explained in terms of better cohesion between the filler and the elastomer compared with more polar fillers such as silicas, china clays china clay, one of the purest of the clays, composed chiefly of the mineral kaolinite usually formed when granite is changed by hydrothermal metamorphism. Usage of the terms china clay and kaolin , etc., having an identical particle size distribution The particle size distribution[1] ("PSD") of a powder, or granular material, or particles dispersed in fluid, is a list of values or a mathematical function that defines the relative amounts of particles present, sorted according to size. . Figure 3 shows the differences in reinforcement through modulus See modulo. measurements of 20% to 200%. Micronized talcs exhibit systematically better strength, at constant elongation, than products in the quartz-kaolinite range at equivalent loading levels and for the same category of hardness. For elongations of less than 50%, modulus values are even higher than those obtained with a compound containing only carbon black N550. This shows the excellent "wettability" of talc by the elastomer. [FIGURE 3 OMITTED] Tensile strength tensile strength Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its and tear resistances obtained with these products are particularly good (tables 1 and 2) even at high mineral loading levels and a low polymer content (table 1). Silane silane or silicon hydride Any of a series of inorganic compounds of silicon and hydrogen with covalent bonds and the general chemical formula SinH(2n + 2). treated micronized talc: Good levels of compression and elongation resistance The weak point of mineral fillers in rubber components is the compression (CS) or elongation set (ES). To eliminate this deficiency, we have developed a surface treated talc. The treatment couples the talc to the elastomer matrix via strong chemical bonds. This increases crosslinking density and improves the elasticity of the material. Figures 4 and 5 demonstrate the effect of the mineral filler concentration on the CS at 100 [degrees] C and 70 [degrees] C. [FIGURE 4 OMITTED] The effect of treatment on micronized talc is especially evident at high loading levels and heavy polymer dilution. The results obtained with this silane treated talc are in accordance with the specifications for EPDM profiles, as in the case of DIN standard 7863 relating to relating to relate prep → concernant relating to relate prep → bezüglich +gen, mit Bezug auf +acc profiles in the building industry (22 hrs. at 100 [degrees] C: <35%). The effect of the surface treatment of micronized talc on compression and elongation characteristics has also been studied in color EPDM profiles. The results are compared to fine kaolinitic quartz and hard clay in figure 6. Traditional mechanical properties are presented in table 3. [FIGURE 6 OMITTED] Micronized talcs: Easier processing Because of their lamellar structure, micronized talcs act as an internal lubricant in rubber material. Less plasticizer is absorbed by these talcs due to relatively low surface area. This is then free in the network to perform its function to the full. This is why micronized talc based rubber materials have such excellent flow. During extrusion, the talc lamellae lamellae (l  mel´ē),n the nearly parallel layers of bone tissue found in compact bone. position themselves in the direction of extrusion flow, thus providing improved hot strength, low die swelling and good outputs (figure 7). [FIGURE 7 OMITTED] Talc also has the lowest Mohs hardness Mohs hardness Rough measure of the resistance of a smooth surface to scratching or abrasion, expressed in terms of a scale devised by German mineralogist Friedrich Mohs in 1812. on the mineral hardness scale and is therefore relatively non-abrasive. This reduces wear in metal fittings such as screws, dies, etc. Another analysis conducted on EPDM compounds with 12%, 22% and 33% mineral filler shows the effect of talcs on extrusion speeds (figure 8). The effect is appreciable ap·pre·cia·ble adj. Possible to estimate, measure, or perceive: appreciable changes in temperature. See Synonyms at perceptible. when there is a high concentration of talc in the compound. As far as injection molding injection molding n. A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold. is concerned, the flow improvement of compounds containing micronized talcs has been demonstrated. Two tests have been chosen (figure 9): [FIGURE 9 OMITTED] * Measurement of injected lengths at constant pressure; * measurement of injection pressures at the end of filling at constant injection rate. It showed that the presence of talc allows injected lengths to be increased by more than 65% and injection pressures to be reduced at the end of filling by 17% (figures 10 and 11). [FIGURE 11 OMITTED] An aid against thermal aging Talc's structure only begins to break down above 920 [degrees] C. It is also chemically inert inert /in·ert/ (in-ert´) inactive. in·ert adj. 1. Sluggish in action or motion; lethargic. 2. , which gives micronized talcs good resistance to acid or basic attacks. The thermal stability of talc-based compounds is shown in figure 12 in which EPDM compounds containing 10% mineral fillers by volume have been subjected to 14 days aging at 100 [degrees] C. These compounds are also compared with a compound containing only carbon black (25% by volume). The mechanical properties are comparable to the pure carbon black compound (table 4), but the flow properties are clearly better in compounds with micronized talc (table 5). [FIGURE 12 OMITTED] In sensitive applications where the use of plasticizer is restricted (food contact or heavy extraction conditions), the use of talcs allows the plasticizer content to be reduced while retaining ease of processing. Moreover, the compounds are less brittle after aging, a phenomenon often linked to significant evaporation evaporation, change of a liquid into vapor at any temperature below its boiling point. For example, water, when placed in a shallow open container exposed to air, gradually disappears, evaporating at a rate that depends on the amount of surface exposed, the humidity of plasticizer. Excellent weathering stability The special properties of micronized talcs open up new application possibilities. An analysis has shown that by optimizing the talc/plasticizer ratio, it was possible for the surface condition after weathering to be almost unchanged from its original condition. After 500 hours of weathering on the Weather-o-meter, the rating on the gray scale reaches 4 to 4/5 depending on the compounds with a maximum of 5. The [DELTA] b values express the degree of yellowing. The lower the value the less significant the degree of yellowing on the surface of the parts. The lamellar structure of talc stops the surface migration of vulcanization by-products and plasticizer, thereby restricting or eliminating problems of iridescence iridescence (ĭr'ədĕs`əns), exhibition of rainbowlike colors on a surface. It usually results from interference when light composed of different wavelengths is reflected from the superficial layers of organic or inorganic substances, . This is important in applications such as external car parts. Conclusions The new micronized talcs: * Improve flow in molding and extrusion; * improve extrusion output and quality; * improve tensile tensile, adj having a degree of elasticity; having the ability to be extended or stretched. and tear properties; * lower compression set and elongation with silane treatment; and * impart excellent weathering stability.
Figure 2 - Mooney viscosity as a function of
mineral filter type
Mooney viscosity: ML 1+4 @ 10 [degrees] C
Fine kaolinitic quartz 55
Hard clay 65
Micronized silane treated talc 42
Note: Table made from bar graph.
Table 1 - mechanical characteristics of black EDPM compounds
containing different mineral fillers
Kaolinitic Untreated Silane treated
quartz/N550 talc/N550 talc/N550
Hardness durometer A, pts. 61 65 65
Tensile strength, MPa 7.5 8.5 8.7
Elongation at break, % 563 516 533
Modulus at 100%, MPa 1.6 2 2.5
Energy at break, J 3.4 3.2 3.6
Tear resistance die C, kN/m 26 29 30
Tear resistance Delft, kN/m 14 16 16
Compression set 22 h. @ 70
[degrees] C, % 19 25 15
Compression set 22 h. @ 100
[degrees] C, % 46 46 34
Elongation set 22 h. @ 100
[degrees] C, % 55 65 48
% elastomer by volume 33 33 33
% carbon black by volume 13 13 13
% mineral filler by volume 16.5 15.5 15.5
Table 2 - mechanical characteristics of a gray NBR containing
different mineral fillers
Calcined Calcined Untreated Treated
clay 1 clay 2 talc talc
Hardness durometer A, pts. 63 62 66 67
Tensile strength, MPa 6.4 5.2 8 8.8
Elongation at break, % 825 797 837 817
Modulus at 100%, MPa 1.6 1.5 2.1 2.4
Tear resistance die C,
kN/m @ 23 [degrees] C 23 22 29 37
Tear resistance die C,
kN/m @ 150 [degrees] C 6 6 8 9
Compression set 70 h. @
100 [degrees] C, % 42 40 50 36
% mineral filler by volume 16.5 16.5 15.7 15.7
% elastomer by volume 79.4 79.4 80 80
Figure 5 - effect of different mineral filler
loading levels on the compression set at 70 [degrees] C
Compression set 22 h. @ 70 [degrees] C
Carbon black N550 10
Fine kaolinitic quartz/N550 19
Kaolinitic quarts/N550 19
Silane treated talc/N550 15
Untreated talc/N550 25
Pure carbon 40% elastomer by volume
16% mineral filler by volume
33% elastomer by volume
Note: Table made from bar graph.
Table 3 - mechanical properties of white EPDM
compounds containing different types of mineral filler
Fine kaolinitic Hard Silane
quartz clay treated talc
Hardness durometer A, pts. 50 54 51
Tensile strength, MPa 6.7 8.1 7.3
Elongation at break, % 630 585 615
Modulus at 100%, MPa 1 1.3 2.3
Energy at break, J 2.4 2.7 3.3
Tear resistance die C, kN/m 23 26.4 25.1
Tear resistance Delft, kN/m 7.4 8.8 8.2
Compression set 22 h. @ 70
[degrees] C, % 19 24 15
Compression set 22 h. @ 100
[degrees] C, % 34 40 27
Elongation set 22 h. @ 100
[degrees] C, % 28 32 23
% above mineral filler by volume 12 12 12
% elastomer by volume 55 55 55
Figure 8 - effect of different filler loading levels
on extrusion speed
Extrusion rates @ 12 pm
12% 22% 33%
Carbon black N550 100
Fine kaolinitic quartz 99 96 99.5
Kaolinitic quartz 86.5 96 98.5
Silane treated talc 96 93 126
Note: Table made from bar graph.
Figure 10 - flow values observed with different
mineral fillers
NBR elastomer
Length in mm at
constant pressure
Calcined clay 1 146
Calcined clay 2 130
Non-treated talc 217
Treated talc 202
Note: Table made from bar graph.
Table 4 - mechanical properties of black EPDMs for molded parts
containing different fillers
Carbon Non
black Kaolinitic treated Treated
Black EPDM for molding N550 quartz talc talc
Hardness duormater A, pts. 75 75 75 77
Tensile strength, MPa 12.9 11.6 14 12.5
Elongation at break, % 280 313 375 340
Modulus at 100%, MPa 5.4 4.2 4.2 5.1
Tear resistance die C @
23 [degrees] C, kN/m 35 26 30 35
Tear resistance die C @
120 [degrees] C 16 12 12 15
Tear resistance die C @
150 [degrees] C 10 10 10 12
Compression set 22 h. @
100 [degrees] C, % 32 44 60 43
% mineral filler by volume 0 10 10 10
% carbon black by volume 25 18 18 18
% elastomer by volume 65 62 62 62
Table 5 - flow properties of black EPDMs for molded parts
containing different filler
Carbon Kaolinitic Non Treated
Black EPDM for molding black quartz treated talc
N550 talc
Injected at constant
pressure, mm 157 144 238 2,174
Pressure at constant
injection rate, bars 592 591 487 511
Mooney viscosity ML (1+4)
@ 100 [degrees] C 71.2 72 55 60
Mooney scorch t5 @ 125
[degrees] C 6 min. 6 min. 7 min. 7 min.
46s 50s 10s 20s
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