JP2009275203A - Rubber composition and vulcanized rubber belt for oa equipment using the rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition free of halogens and phosphorus, good in processability while exhibiting excellent flame retardancy, and a vulcanized rubber belt for an OA device, manufactured by using the composition. <P>SOLUTION: This rubber composition comprises rubber components containing EPDM as a main constituent, and 90-300 pts.wt. of aluminum hydroxide and 2-10 pts.wt. of a higher fatty acid metal salt and/or a higher fatty acid ester, each to 100 pts.wt. of rubber component, and preferably further comprises 3-30 wt.% magnesium hydroxide to aluminum hydroxide, and not including halogens or phosphorus. The vulcanized rubber belt for an OA device is produced by using the rubber composition, molding and vulcanizing it. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber composition that exhibits excellent flame retardancy, has good processability and does not contain halogen or phosphorus, and a vulcanized rubber belt for OA equipment manufactured by using the composition. Is.

  In so-called OA equipment such as plain paper copiers, color copiers, laser beam printers, facsimiles, etc. that use black toner or multiple types of color toner using the basic principle of electrophotography, the power is turned on regardless of day or night. Many products are used in the state, and the safety of the OA equipment as a whole is regulated from the viewpoint of fire prevention. In addition to resin products such as housings, the parts used inside are also compliant with the specified flame retardant standards. It is required to pass.

  Therefore, excellent flame retardancy, specifically, evaluation by the UL94 VTM method is also applied to a vulcanized rubber belt which is a seamless belt base material such as an intermediate transfer belt and a transfer conveyance belt used in such OA equipment. It may be required to have flame retardancy that can be achieved.

  For the purpose of achieving such flame retardancy, for example, in Patent Document 1 below, chloroprene rubber and EPDM (ethylene propylene rubber) are the main components, and aluminum hydroxide is 1 to 100 parts by weight of the rubber component. A rubber belt produced by molding and vulcanizing a rubber composition containing 100 parts by weight is described. Vulcanized rubber using such a rubber composition exhibits excellent flame retardancy mainly due to the halogen contained in the chloroprene rubber.

  However, vulcanized rubber containing halogen may generate harmful gases such as dioxins during combustion. From the viewpoints of safety and environmental impact during disposal / incineration, halogenated substances However, it is not preferable to use a rubber composition containing halogen.

  In the following Patent Document 2, a rubber composition containing 60 to 120 parts by weight of aluminum hydroxide surface-treated with a fatty acid or a silane coupling agent and 4 to 15 parts by weight of red phosphorus is molded and vulcanized to 100 parts by weight of EPDM. A rubber belt produced by this is described. However, a rubber composition containing a phosphorus compound such as red phosphorus is insufficient in safety and environmental harmony, and in addition, there is a risk of mold corrosion, gas generation, etc. during molding processing. For this reason, development of a rubber composition that does not contain halogen or phosphorus and can cope with environmental problems is required.

As a rubber composition containing no halogen or phosphorus, Patent Document 3 below describes a rubber belt produced using a rubber composition containing 10 to 50 parts by weight of expansive graphite with respect to 100 parts by weight of EPDM. . In such a rubber belt, although it exhibits excellent flame retardancy due to the expandable graphite, the graphite may remain in a lump in the vulcanized rubber and the smoothness of the belt surface may be insufficient.
JP 2000-110891 A JP 2005-97493 A JP 2005-154567 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber composition that exhibits excellent flame retardancy, has good processability, and does not contain halogen or phosphorus, and the composition. An object of the present invention is to provide a vulcanized rubber belt for OA equipment produced by use.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by a rubber composition shown below and a vulcanized rubber belt for OA equipment produced by using the composition, The present invention has been completed.

  That is, the rubber composition according to the present invention is a rubber composition containing a rubber component containing EPDM as a main component, and 90 to 300 parts by weight of aluminum hydroxide and higher fatty acid metal salt with respect to 100 parts by weight of the rubber component. Alternatively, it is characterized in that it contains 2 to 10 parts by weight of at least one of higher fatty acid esters and does not contain halogen or phosphorus.

  In general, in OA equipment, in which an image is formed by a so-called electrophotographic method, charging is performed by corona discharge using a high voltage as a means for charging a photoreceptor, and the ozone concentration in the OA equipment is increased. The rubber composition exhibits excellent ozone resistance by containing a rubber component mainly composed of EPDM. Moreover, by containing 90 to 300 parts by weight of aluminum hydroxide with respect to 100 parts by weight of the rubber component, the vulcanized rubber of the rubber composition exhibits excellent flame retardancy, and specifically, evaluation by the UL94VTM method is possible. The flame retardance which can achieve VTM-0 is shown. On the other hand, when the rubber composition contains a large amount of aluminum hydroxide, the viscosity in the rubber composition is remarkably increased. For example, when the rubber composition is extruded, the processability deteriorates. By containing 2 to 10 parts by weight of at least one of higher fatty acid esters, the vulcanized rubber exhibits excellent flame retardancy while improving the processability of the rubber composition. Furthermore, since the rubber composition according to the present invention does not contain halogen or phosphorus, it can cope with environmental problems.

  The rubber composition according to the present invention is a rubber composition containing a rubber component containing EPDM as a main component, and 90 to 300 parts by weight of aluminum hydroxide with respect to 100 parts by weight of the rubber component, and the aluminum hydroxide. 3 to 30% by weight of magnesium hydroxide and no halogen or phosphorus.

  Generally, in a rubber composition containing a rubber component containing EPDM as a main component and containing a large amount of aluminum hydroxide, for example, when the rubber composition is roll-molded or extruded, the rubber composition has high adhesiveness. Due to this, the releasability between the rubber composition and the roll may be remarkably impaired by being wound around the roll, or the rubber composition may be retained in the extruder to cause rubber burn or the like. However, in a rubber composition containing a rubber component whose main component is EPDM, when a predetermined amount of aluminum hydroxide and 3 to 30% by weight of magnesium hydroxide with respect to aluminum hydroxide are contained, the rubber composition The above-described problems during roll molding and extrusion molding are effectively prevented.

  The rubber composition preferably further contains 2 to 10 parts by weight of at least one of a higher fatty acid metal salt or a higher fatty acid ester. In such a rubber composition, the flame retardance of the vulcanized rubber can be improved while further improving the workability by effectively suppressing the increase in viscosity and the increase in adhesiveness.

  Another vulcanized rubber belt for OA equipment according to the present invention is obtained by molding and vulcanizing using the above rubber composition. The vulcanized rubber belt for OA equipment contains a predetermined amount of aluminum hydroxide and a predetermined amount of at least one of a higher fatty acid metal salt or a higher fatty acid ester, so that excellent rubber elasticity is maintained and excellent difficulty is maintained. Since it has flammability, it is extremely useful as a vulcanized rubber belt for OA equipment which is a seamless belt substrate such as an intermediate transfer belt and a transfer conveyance belt.

  In the rubber composition according to the present invention, the content of EPDM as a main component, that is, the content of EPDM in the rubber component is 80% by weight or more, preferably 90% by weight or more. When the content of EPDM in the rubber component is less than 80% by weight, the ozone resistance of the vulcanized rubber is deteriorated, which is not preferable. Examples of rubber that can be blended as a rubber component in addition to EPDM include polyisoprene rubber, polystyrene butadiene rubber, polybutyl rubber, and polyacrylonitrile butadiene rubber. Such rubber may be used alone or in combination of two or more.

  The rubber composition according to the present invention contains 90 to 300 parts by weight of aluminum hydroxide as a flame retardant with respect to 100 parts by weight of the rubber component. When the content of aluminum hydroxide in the rubber composition is less than 90 parts by weight with respect to 100 parts by weight of the rubber component, the flame retardancy of the vulcanized rubber is not sufficiently improved, and when it exceeds 300 parts by weight, the rubber composition The workability of the object deteriorates. Here, as the content of aluminum hydroxide in the rubber composition increases, the flame retardancy of the vulcanized rubber is improved, but the processability of the rubber composition deteriorates, but will be described later in the rubber composition. By containing a predetermined amount of at least one of a higher fatty acid metal salt or a higher fatty acid ester, the processability of the rubber composition can be satisfactorily maintained even if the rubber composition contains a large amount of aluminum hydroxide. . When considering the processability of the rubber composition and the flame retardancy of the vulcanized rubber, the content of aluminum hydroxide in the rubber composition is preferably 130 to 300 parts by weight with respect to 100 parts by weight of the rubber component, 180 -300 weight part is more preferable.

  The rubber composition according to the present invention preferably contains 3 to 30% by weight of magnesium hydroxide with respect to aluminum hydroxide. If the content of magnesium hydroxide relative to aluminum hydroxide is less than 3% by weight, the tackiness of the rubber composition during processing may not be reduced effectively. If the content exceeds 30% by weight, deformation of the vulcanized rubber may occur. As a result, the rubber elasticity required for a vulcanized rubber belt becomes difficult to maintain. In order to effectively reduce the tackiness of the rubber composition during processing while reducing the permanent set resistance to deformation of the vulcanized rubber, the content of magnesium hydroxide relative to aluminum hydroxide is 5 to 20% by weight. It is preferable that it is 10 to 15% by weight.

  The rubber composition according to the present invention contains 2 to 10 parts by weight of at least one of a higher fatty acid metal salt or a higher fatty acid ester as a processing aid with respect to 100 parts by weight of the rubber component. When the content of at least one of the higher fatty acid metal salt or higher fatty acid ester in the rubber component is less than 2 parts by weight relative to 100 parts by weight of the rubber component, the processability of the rubber composition, particularly the extrudability, is sufficiently improved. Without exceeding 10 parts by weight, the permanent set resistance to deformation of the vulcanized rubber is increased, and it is difficult to maintain the rubber elasticity required for the vulcanized rubber belt.

  The higher fatty acid metal salt or higher fatty acid ester is an alkali metal salt or alkaline earth metal salt of higher fatty acid, or an ester substitution product of higher fatty acid. Examples of higher fatty acids include oleic acid, palmitic acid, stearic acid, lauric acid, linoleic acid, abietic acid, erucic acid, myristic acid, arachidic acid, lignoceric acid, and the like, and one or more of these may be mixed. Can be used. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid, but is preferably composed mainly of an unsaturated fatty acid. Examples of the alkali metal include lithium, potassium, and sodium. Examples of the alkaline earth metal include barium, calcium, magnesium, aluminum, iron, and zinc. Among these, a zinc salt is preferable. The ester substituent in the higher fatty acid ester is not particularly limited.

  In the rubber composition according to the present invention, in addition to the rubber component, aluminum hydroxide, magnesium hydroxide, and higher fatty acid metal salt or higher fatty acid ester, sulfur, carbon black, vulcanization accelerator, anti-aging agent, vulcanization Additives usually used in the rubber industry such as accelerator aids, vulcanization retarders, silica, silane coupling agents, zinc oxide, stearic acid, plasticizers, softeners such as wax and oil, processing aids, etc. It can mix | blend suitably and can be used in the range which does not impair the effect of invention.

  Sulfur should just be normal sulfur for rubber | gum, For example, powder sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur etc. can be used. The sulfur content in the rubber composition according to the present invention is 0.5 to 3 parts by weight with respect to 100 parts by weight of the rubber component. If the sulfur content is less than 0.5 parts by weight, the crosslinking density of the vulcanized rubber will be insufficient and the rubber strength will be reduced. If it exceeds 3 parts by weight, the heat resistance of the vulcanized rubber will deteriorate. In order to ensure good rubber strength of the vulcanized rubber and further improve heat resistance, the sulfur content is preferably 0.5 to 2 parts by weight with respect to 100 parts by weight of the rubber component. More preferably, it is 1.5 parts by weight.

  As carbon black, for example, conductive carbon black such as acetylene black and ketjen black is used in addition to carbon black used in normal rubber industry such as SAF, ISAF, HAF, FEF, and GPF. The amount of carbon black in the rubber composition according to the present invention is 10 to 10 parts by weight with respect to 100 parts by weight of the rubber component in consideration of rubber properties such as conductivity, hardness, reinforcement, and low heat build-up of the vulcanized rubber. The range is 60 parts by weight, preferably 20 to 40 parts by weight.

  As the vulcanization accelerator, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization, which are usually used for rubber vulcanization. Vulcanization accelerators such as accelerators and dithiocarbamate vulcanization accelerators may be used alone or in admixture as appropriate.

  As an anti-aging agent, an aromatic amine-based anti-aging agent, an amine-ketone-based anti-aging agent, a monophenol-based anti-aging agent, a bisphenol-based anti-aging agent, a polyphenol-based anti-aging agent, dithiocarbamic acid, which are usually used for rubber You may use antiaging agents, such as a salt type anti-aging agent and a thiourea type anti-aging agent, individually or in mixture as appropriate.

  The rubber composition according to the present invention includes a rubber component, aluminum hydroxide, magnesium hydroxide, and a higher fatty acid metal salt or higher fatty acid ester, sulfur, carbon black, a vulcanization accelerator, an anti-aging agent, a vulcanization acceleration aid, Vulcanization retarders, silica, silane coupling agents, zinc oxide, stearic acid, plasticizers, softeners such as wax and oil, processing aids, etc. are used in the normal rubber industry such as Banbury mixers, kneaders, rolls, etc. It can be obtained by kneading using a kneader.

  Further, the blending method of each component in the rubber composition is not particularly limited, and a blending component other than the vulcanization system component such as sulfur and a vulcanization accelerator is kneaded in advance to obtain a master batch, and the remaining components are added. Further, a kneading method, a method of adding and kneading each component in an arbitrary order, a method of adding all components simultaneously and kneading may be used.

  By using the rubber composition according to the present invention, molding and vulcanization, a vulcanized rubber belt for OA equipment can be produced. Such a vulcanized rubber belt for OA equipment can be produced by a known method. The production method includes a kneading step for kneading a rubber raw material and its compounding material by a conventional method to produce a heat-crosslinkable unvulcanized rubber composition, and a molding step for molding the unvulcanized rubber composition into an endless belt shape. Have. The molding process uses a known method such as an injection molding method or an extrusion molding method.

  The injection molding method preferably uses a double cylindrical mold having a cylindrical or columnar middle mold and a cylindrical outer mold, and is formed by a belt-shaped cavity formed by the outer surface of the middle mold and the inner surface of the outer mold. This is performed by injecting an unvulcanized rubber composition. The temperature of the mold is 100 to 200 ° C, preferably 140 to 180 ° C, and the preheat temperature of the unvulcanized rubber composition is 60 to 120 ° C, preferably 70 to 110 ° C.

  The extrusion molding method is preferably performed by using an extruder equipped with a crosshead, supplying a cylindrical or columnar mandrel to the crosshead, and forming an unvulcanized rubber composition layer around the mandrel. Let it be done. The preheating temperature of the unvulcanized rubber composition is 60 to 120 ° C, preferably 70 to 110 ° C. The extrusion speed is appropriately set in consideration of the discharge capacity of the extruder and the size of the belt.

  In addition, when manufacturing a vulcanized rubber belt by the said extrusion method, it is good also as a laminated belt of rubber | gum and high-rigidity resin by carrying out lamination | extrusion extrusion with high-rigidity resin. Examples of high-rigidity resin materials that can be laminated with rubber include polyester resins such as polyimide resin, PBT, PET, and PEN, polycarbonate, PBT / polycarbonate blend resin, polyethersulfone (PES), polyetheretherketone (PEEK), PES / PEEK blend resin etc. are mentioned. When a laminated belt of rubber and high-rigidity resin is used, a belt having a rubber layer on the outer surface of the high-rigidity resin layer can be manufactured by providing a mandrel with a high-rigidity resin layer in advance and supplying the crosshead. it can.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the evaluation item in an Example etc. measured as follows.

<Flame retardance>
A vulcanized rubber sheet sample (200 mm x 50 mm) is subjected to flame contact for 3 seconds-2 times using a burner, and evaluated according to the UL94VTM method based on the combustion time and sample state after each flame contact. went. Those corresponding to UL94VTM-0 were marked with ◯, and those not applicable with x.

<Processability>
If the rubber composition is extruded by an extrusion device such as an extruder, and the belt-shaped rubber can be extruded without the occurrence of rubber burn, etc., the rubber belt after extrusion by rubber burn etc. The case where deterioration of the surface smoothness in was observed visually was set as x.

<Ozone resistance>
A vulcanized rubber sample stretched 20% in a constant temperature room with an ozone concentration of 5 ppm to 40 ° C. is taken out after standing for 240 hours, and the vulcanized rubber sample is visually observed. X.

<Permanent strain>
A vulcanized rubber sample stretched 50% in a constant temperature room at 70 ° C. is taken out after 24 hours and left at room temperature. If the vulcanized rubber sample has an elongation of 30% or less, it is evaluated as ◯. When the elongation of the wire exceeded 30%, it was evaluated as x.

(Preparation of rubber composition)
According to the formulation of Table 1, the rubber compositions of Examples 1 and 2 and Comparative Examples 1 to 4 were blended and kneaded using a normal Banbury mixer to prepare a rubber composition. Each compounding agent described in Table 1 is shown below.
a) Rubber component
(A) EPDM (“Esplen 505”, manufactured by Sumitomo Chemical Co., Ltd.)
(B) SBR ("JSR1500", manufactured by JSR Corporation)
b) Aluminum hydroxide (A) 1 μm aluminum hydroxide (“Hijilite H-42”, manufactured by Showa Denko KK)
(B) 8 μm aluminum hydroxide (“Hijilite H-32”, Showa Denko)
c) Higher fatty acid metal salt ("Stractol A60", manufactured by Shill Seilacher)
d) Zinc oxide No. 3 zinc white

e) Stearic acid Industrial stearic acid f) Carbon black Acetylene black ("Electrical black", manufactured by Denki Kagaku Kogyo)
g) Plasticizer ("PW-90", manufactured by Idemitsu Kosan Co., Ltd.)
h) Sulfur 5% oil-treated sulfur i) Vulcanization accelerator N-Cyclohexyl 2-benzothiazolylsulfenamide ("Noxeller CZ-G (CZ)", manufactured by Ouchi Shinsei Chemical Co., Ltd.)
j) Magnesium hydroxide ("Kisuma 5A", manufactured by Kyowa Chemical Co., Ltd.)

(Examples and comparative examples)
Each rubber composition was vulcanized and molded to a predetermined thickness (vulcanization time 160 ° C., vulcanization temperature 40 minutes) to produce each vulcanized rubber and evaluated the characteristics. The results are shown in Table 1.

  From the results of Table 1, the rubber compositions of Examples 1-2 are excellent in processability, and the vulcanized rubbers of the rubber compositions of Examples 1-2 are any of flame retardancy, ozone resistance, and permanent strain. It turns out that it is excellent also in the characteristic. On the other hand, since the vulcanized rubber of the rubber composition of Comparative Example 1 has a low aluminum hydroxide content, the vulcanized rubber has poor flame retardancy, and the vulcanized rubber of the rubber composition of Comparative Example 2 is (higher fatty acid). It can be seen that since the content of at least one of the metal salt or the higher fatty acid ester) is large, the permanent strain of the vulcanized rubber is large and the rubber elasticity of the vulcanized rubber cannot be maintained. Further, the rubber composition of Comparative Example 3 has poor processability due to the high content of aluminum hydroxide, and the rubber composition of Comparative Example 4 does not contain (at least one of higher fatty acid metal salt or higher fatty acid ester). It turns out that workability is still bad.

  From the results of Table 2, the rubber compositions of Examples 5 to 7 are excellent in processability, and the vulcanized rubbers of the rubber compositions of Examples 5 to 7 are any of flame retardancy, ozone resistance and permanent strain. It turns out that it is excellent also in the characteristic. On the other hand, since the vulcanized rubber of the rubber composition of Comparative Example 6 has a low aluminum hydroxide content, the flame retardancy of the vulcanized rubber is poor, and the rubber composition of Comparative Example 7 is hydroxylated against aluminum hydroxide. It can be seen that since the magnesium content is large, the permanent set of the vulcanized rubber is large and the rubber elasticity of the vulcanized rubber cannot be maintained. It can also be seen that the rubber compositions of Comparative Example 8 and Comparative Example 9 both have poor processability, and in addition, the vulcanized rubber of the rubber composition of Comparative Example 9 has a large permanent strain and cannot maintain rubber elasticity.

Claims (4)

In a rubber composition containing a rubber component mainly composed of EPDM,
90 to 300 parts by weight of aluminum hydroxide and 2 to 10 parts by weight of at least one of a higher fatty acid metal salt or a higher fatty acid ester and 100% by weight of the rubber component and not containing halogen or phosphorus A rubber composition. In a rubber composition containing a rubber component mainly composed of EPDM,
It contains 90 to 300 parts by weight of aluminum hydroxide with respect to 100 parts by weight of the rubber component, 3 to 30% by weight of magnesium hydroxide with respect to the aluminum hydroxide, and does not contain halogen or phosphorus. A rubber composition.   The rubber composition according to claim 2, further comprising 2 to 10 parts by weight of at least one of a higher fatty acid metal salt or a higher fatty acid ester.   A vulcanized rubber belt for OA equipment obtained by molding and vulcanizing using the rubber composition according to claim 1.