Garbelotto, Paulo Roberto (Rua Geraldo Trefíglio, 38 Jardim Aruã, -309 Campinas, 13085, BR)
De Paiva, Ana Antonia (Rua Barata Ribeiro, 186 - aptº 14 Jardim Guanabara, -030 Campinas, 13023, BR)
Garbelotto, Paulo Roberto (Rua Geraldo Trefíglio, 38 Jardim Aruã, -309 Campinas, 13085, BR)
|1.||PRECIPITATED SILICA REINFORCED EPDM RUBBER FORMULATION, wherein it comprises: (a) one or more EPDM polymers; (b) at least one high dissipating precipitated silica as reinforcing filler; (c) nonreinforcing filler; (d) antioxidant; (e) interface agent and/or coupling agent; (f) desiccating; (g) accelerating activator; (h) vulcanization additives.|
|2.||FORMULATION, according to claim 1 , characterized in that the proportion of one or more EPDM polymers is of about 100 phr.|
|3.||FORMULATION, according to claim 1 , characterized in that one or more EPDM polymers present contents of about 0.1 to 15% of double coupling in their structural formula.|
|4.||FORMULATION, according to claim 1 , characterized in that said silica presents a superficial area between about 30 to about 100 m2/g.|
|5.||FORMULATION, according to claim 4, characterized in that said silica presents a low superficial area of about 50 m2/g.|
|6.||FORMULATION, according to claim 1 , characterized in that the silica amount is of about 50 to 250 phr.|
|7.||FORMULATION, according to claim 6, characterized in that the silica amount is of about 100 to about 200 phr.|
|8.||FORMULATION, according to claim 7, characterized in that the silica amount is of about 150 to about 175 phr.|
|9.||FORMULATION, according to claim 1 , characterized in that the interface agent is polyethylene glycol (PEG) and/or triethanolamine (TEA).|
|10.||FORMULATION, according to claim 9, characterized in that the PEG interface agent varies from about 0 to about 10 phr.|
|11.||FORMULATION, according to claim 10, characterized in that the PEG interface agent varies from about 3 to about 6 phr.|
|12.||FORMULATION, according to claim 11 , characterized in that the PEG interface agent varies from about 4 to about 4.5 phr.|
|13.||FORMULATION, according to claim 9, characterized in that the TEA interface agent varies from about 0.5 to about 5 phr. 14.|
|14.||FORMULATION, according to claim 13, characterized in that the TEA interface agent varies from about 1 to about 4 phr.|
|15.||FORMULATION, according to claim 14, characterized in that the TEA interface agent varies from about 1.5 to about 3 phr.|
|16.||FORMULATION, according to claim 1 , characterized in that the coupling agent is a silane.|
|17.||FORMULATION, according to claim 16, characterized in that the coupling agent is organosilane.|
|18.||FORMULATION, according to claim 17, characterized in that the organosilane amount is of about 0 to about 11 phr.|
|19.||FORMULATION, according to claim 18, characterized in that the organosilane amount is of about 3 to about 9 phr.|
|20.||FORMULATION, according to claim 19, characterized in that the organosilane amount is of about 7.5 to about 8.5 phr.|
|21.||FORMULATION, according to claim 1 , characterized in that the desiccating is calcium oxide.|
|22.||FORMULATION, according to claim 21 , characterized in that the calcium oxide amount is from about 5 to about 50 phr.|
|23.||FORMULATION, according to claim 22, characterized in that the calcium oxide amount is from about 8 to about 30 phr.|
|24.||FORMULATION, according to claim 23, characterized in that the calcium oxide amount is from about 22 to about 26 phr.|
|25.||FORMULATION, according to claim 1 , characterized in that the acceleration activator is zinc oxide.|
|26.||FORMULATION, according to claim 25, characterized in that the zinc oxide amount is from about 15 to about 30 phr.|
|27.||FORMULATION, according to claim 26, characterized in that the zinc oxide amount is of about 25 phr.|
|28.||FORMULATION, according to claim 1 , characterized in that it comprises one or more excipients like antioxidant, process oil, sulphur, stearic acid and pigment.|
|29.||FORMULATION, according to claim 28, characterized in that said pigments are chosen among titanium dioxide, iron oxide, black carbon, and organic pigments.|
|30.||PROCESS FOR THE MANUFACTURING OF REINFORCED EPDM RUBBER FORMULATION, characterized in that it comprises the following steps: (a) mixing EPDM, antioxidant, reinforcing filler, interface agent, coupling agent, process oil, and desiccating in an internal mixer up to the temperature of 14O0C to 190°C and keeping the mass in such temperature for about 3 to 10 minutes; (a1) adding remaining ingredients according to formulation; (b) putting the obtained mass between opening mixer rolls, adding pigments, vulcanization accelerators and sulphur, and then homogenizing said components.|
|31.||PROCESS, according to claim 30, characterized in that the mixing of the ingredients is made in an ordered way.|
|32.||PROCESS, according to claims 30 and 31 , characterized in that the temperature of the internal mixer reaches about 15O0C.|
|33.||PROCESS, according to claim 32, characterized in that the temperature of the internal mixer is kept for at least 3 minutes.|
|34.||PROCESS, according to one of claims 30 to 33, characterized in that the formulation process oil is inserted in distinct phases in the mixing process.|
|35.||PROCESS, according to claim 34, characterized in that the amount of the process oil inserted in the step (a) is of 60%.|
|36.||PROCESS, according to claim 34, characterized in that the amount of the process oil inserted in the step (a1) is of 40%.|
|37.||PROCESS FOR THE OBTAINMENT OF A REINFORCED RUBBER PROFILE, characterized in that a formulation obtained as described in claim 30 is: (i) extruded, particularly in a monoscrew extruder; and (ii) the profile obtained by extrusion is vulcanized in a trotter treadmill, in a warm tunnel, in a temperature between about 1500C to about 280°C.|
|38.||PROCESS, according to claim 37, characterized in that the temperature of the step (ii) is from about 2400C to about 2500C.|
|39.||COLORED EXTRUDED RUBBER PROFILE, characterized in that it is obtained by the process described in claim 30.|
|40.||USE OF A REINFORCED RUBBER FORMULATION, as described in one of claims 1 to 29, characterized in that it is for the obtainment of a join element and/or part seal, specifically an extruded profile.|
|41.||USE, according to claim 40, characterized in that said profile is colored.|
MANUFACTURING PROCESS, PROCESS FOR THE OBTAINMENT OF A
REINFORCED RUBBER PROFILE, COLORED EXTRUDED RUBBER
PROFILE AND USE" FIELD OF THE INVENTION
The present invention refers to a high dissipating precipitated silica reinforced EPDM (monomer of ethylene-propylene-diene) rubber formulation and a colored extruded polymeric profile comprising said formulation, particularly intended for using in building and automobile industry. The invention also refers to a manufacturing process of said formulation.
BACKGROUND OF THE INVENTION
It is known several kinds of polymers for production of profiles, such as polyvinyl chloride (PVC), monomer of ethylene-propylene-diene (EPDM) and silicone rubber, specifically useful for building and automobile industry.
French patent FR 0.272.361 discloses a process for the manufacturing of a PVC article, particularly with addition of EPDM. PVC profiles present a relatively low cost, but however, have inferior mechanic properties, more particularly low resistance to intemperate weather. EPDM is a material that presents excellent resistance to intemperate weather, to ozone and to temperatures variations. EPDM has a performance superior than PVC (polyvinyl chloride), SBR (Copolymer of Butadiene and Styrene) and others, which are little compatible to continuous thermal changes. EPDMs are amorphous polymers except for high ethylene grades when develop crystallization in the drawing, and consequently, they must be reinforced in order to achieve better properties.
US Patent 6.279.633 discloses a composition of precipitated silica
reinforced EPDM rubber (with superficial area of about 110 to 130m 2 /g) mixed with organosilane disulfide, optionally using black carbon in its composition.
The use of silica as reinforce filler in formulations for rubber articles formulations has depicted a good market alternative due to it is possibility to substitute black carbon by introducing a new option of coloring in rubber profiles with similar characteristics, since black carbon reinforce filler is limited to the black color.
Recently, the company Rhodia has developed a silicone rubber profile (Rhodiastic ® ) that is highly hydrophobic and self-regenerative, having superior resistance under severe and demanding conditions of assembly and usage, climate and pollution. This profile may be colored, presenting excellent electric and mechanic properties, however it has a cost related to market premium sectors. Due to previous technology, it was needed to develop a colored profile improved with mechanic properties similar to the ones obtained with black carbon, presenting resistance to intemperate weather, but with a lower cost in relation to silicone rubber profile, as developed by the Applicant. It refers to an improved reinforced EPDM rubber formulation with high dissipating precipitated silica to the manufacture of colored profiles and with suitable mechanic properties.
DESCRIPTION OF THE INVENTION
The present invention refers, as a first object, to a formulation for reinforced EPDM rubber, wherein it comprises: (a) one or more EPDM polymers;
(b) at least one high dissipating precipitated silica as reinforcing filler;
(c) non-reinforcing filler;
(Θ) interface agent and/or coupling agent;
(g) accelerating activator; (h) vulcanization additives.
The formulation of the invention allows obtaining colored profiles highly resistant to intemperate weather, being characterized by having in its EPDM rubber formulation a high dissipating precipitated silica (HDS prepared silica) that presents as an important physic-chemical characteristic a low superficial area, between about 30 to 100 m 2 /g, particularly of about 50 m 2 /g. As to the amount of precipitated silica, the formulation comprises about 50 to 250 phr (parts by one hundred of rubber), particularly about 100 to 200 phr and, more specifically, about 150 to 175 phr.
The concentration of EPDM in the formulation of the invention may vary according to mechanic and structural properties desired for the final product, as a person skilled in the art knows to determine it. Particularly, the proportion of one or more polymers of EPDM used in the present invention is of 100 phr.
Polymers of EPDM useful in the present invention preferably present (without excluding any alternatives) contents of about 0.1 to 15% of double coupling in their structural formula, an useful characteristic to control vulcanization process.
The use of non-reinforcing filler in the formulation of the present invention, as calcinated clay, provides a better aspect for an EPDM profile. Interface agents, such as polyethylene glycol (PEG) or triethanolamine (TEA) improve the compatibility between HDS precipitated silica and the EPDM polymer. According to the present invention, the interface agents may vary in amounts of about 0 to 10 phr, particularly from about 3 to 6 phr. In
case of PEG, preferably from about 4 to 4.5 phr. In case of TEA, from about 0.5 to 5 phr, particularly from 1 to 4 phr, preferably about 1.5 to 3 phr.
Coupling agents, such as organosilane, proportionate compatibility between silica and the polymer, generating compounds with good mechanic properties. The amount of coupling agent in the present invention may vary from about 0 to 11 phr, particularly from about 3 to 9 phr, preferably about 7.5 to
The amounts of interface and coupling agents are significantly proportional to the amount of silica used in the present invention. The formulation of the present invention still uses a desiccating, for instance calcium oxide (CaO), in an amount particularly from about 5 to 50 phr, more particularly from about 8 to 30 phr and even more particularly from about 22 to 26 phr. The presence of high dissipating precipitated silica in the present formulation suggests the use of superior amounts of the desiccating with the property of reducing the humidity rate.
One of the accelerating activators used in the present invention is zinc oxide employed in high concentration, for instance, between about 15 and 30 phr, particularly about 25 phr.
Other components, such as antioxidant, process oil, stearic acid, vulcanization accelerators, sulphur, and chemically acceptable excipients are employed in the formulation of the present invention according to practices known in the art.
One excipient specific for the formulation of the present invention is one or more pigments to provide color to the mass obtained by the process mentioned below. Without any limitation, some of the pigments suitable are: titanium dioxide, iron oxide, black carbon, or organic pigments.
Process oil useful to the formulation acts in the process and in the final properties of the product. An example of process oil is paraffinic oil.
Comparative examples of formulations having known black carbon
NF550 and HDS precipitated silica (exemplified in the case by silica ZS40, sold by
Rhodia Brasil Ltda) are described below. These examples show that by substituting black carbon by HDS silica in a formulation is necessary to make some changes in the formulation so that the rheologic, rheometric and mechanic properties are similar:
• To use more accelerators, or to adjust the vulcanization system;
• To adjust the dose of oil process; and
• To include interface agents and/or coupling agents.
(1) Perkacit MBTS, sold by Flexsys;
(2) Perkacit TMTD, sold by Flexsys;
(3) Perkacit ZDBC, sold by Flexsys;
(4) Perkacit ZDMC 1 sold by Plexsys; EXAMPLE Il
(5) Perkacit MBT 1 sold by Plexsys;
(6) Perkacit TMTM, sold by Plexsys;
(7) Perkacit DTDM, sold by Plexsys;
COMPARATIVE TABLE OF THE RHEOMETRIC, RHEOLOGIC AND MECHANICAL
(8) Fast maturing in incubator; exposition for 70 hours, at 70 0 C.
(9) Exposition for 22 hours at 7O 0 C.
(10) Exposition for 70 hours at 40 0 C, 50 ppcm over mandrill.
In another aspect, the present invention refers to a manufacturing process of said formulation with stages suitable to the desired properties, as well as its extruded colored profile. The process of the present invention comprises the basic stages of:
(a) Mixing; and
(b) Extrusion and vulcanization PROCESS MIXING STAGE
EPDM rubber, antioxidant, HDS precipitated silica, interface agent, coupling agent, 60% of the amount of process oil, for instance, paraffinic and desiccating are mixed in an internal mixer, for instance, Banbury type or with rotating sigma bladders, for obtaining a mass. When the temperature of the mass achieves about 140 to 190 0 C, preferably 150 0 C, the process of mixing must be kept for about 3 minutes. It is important that the achieved temperature is high, preferably about 150 0 C, so that the free water presented in the silica evaporates during the process of mixing, and does not provoke the formation of bubbles inside the profile during the extrusion and vulcanization stage.
In the following, the rest of the ingredients, according to the formulation is added, for instance 40% of the amount of the oil process, non-
reinforcing fillers (calcined kaolin, calcium carbonate), zinc oxide, stearic acid, and flow agent, unload the homogenized pasty.
It is necessary to add to the formulation an efficient desiccating like CaO in amounts superiors than the commonly used in order to react with free water presented in silica, forming calcium hydroxide stable in temperatures of vulcanization and then avoiding the formation of bubbles inside the profile.
The obtained mass is then placed between the cylinder rolls of an opening mixer by adding pigments, vulcanization accelerators and sulphur (responsible for the occurring of vulcanization process). The mass is totally homogenized.
EXTRUSION AND VULCANIZATION STAGE
The profile is obtained by an extruder, usually monoscrew. Immediately after its extrusion, the rubber profile is placed in a vehicle, for instance, a treadmill trailer that enters in a warmed tunnel to vulcanize in a temperature of about 150 0 C to 280 0 C, preferably between about 240 and 250, about 21O 0 C. The speed of the treadmill roller is regulated in order to guarantee the rubber to be inside the tunnel for enough time to complete the vulcanization reaction.
It is important to make the vulcanization reaction to happen fast, as another way to minimize the bubbles formation caused by the free water present in the HDS precipitated silica. For this purpose, the dosages of the accelerators must be raised and of ZnO in bigger proportion than the ones used in the art must be added because zinc oxide is also favorable for a better thermal conductivity of the material and makes the vulcanization in the center of the profile to begin fast.
In a third aspect, the present invention refers to the use of the reinforced EPDM with high dissipating precipitated silica formulation previously depicted, characterized for being in the obtainment of a join element and/or part
sealing, particularly an extruded profile, useful in the industry, for instance, building and automotive industry.
From the teachings mentioned herein, a person skilled in the art will know how to propose several equivalent embodiments not specifically mentioned, but that are guaranteed by the attached claims.