JP5154748B2 - Processing method for continuous organic peroxide crosslinked rubber molded body and crosslinked rubber molded body - Google Patents

Description

  The present invention relates to a method for processing a crosslinked rubber molded article obtained from an ethylene / α-olefin copolymer rubber composition that can be crosslinked in hot air. More specifically, the present invention relates to a method for processing a crosslinked rubber molded article obtained from an ethylene / α-olefin copolymer rubber composition, in which an organic peroxide crosslinked composition can be crosslinked in air. The present invention also relates to a crosslinked rubber molded product obtained by the processing method.

  Since ethylene / propylene / diene copolymer rubber (EPDM) has no unsaturated groups in the main chain, it has superior heat resistance and weather resistance compared to general-purpose diene rubber. It is often used for strips and hoses.

  EPDM often uses sulfur as a crosslinking agent, but PO-crosslinked EPDM rubber material using organic peroxide (PO) as a crosslinking agent exhibits excellent heat resistance and compression set, and the required performance is It is an indispensable material for strict automotive applications. For example, the water-based rubber hose is produced by a method of cross-linking in a batch manner in the presence of pressurized steam after extrusion molding. Weather strips have been commercialized by a method of continuous crosslinking under hot air.

  By the way, in the sulfur vulcanization, the product surface is not sticky, and the generation of voids seen when crosslinking is insufficient is not observed. However, in cross-linking using a PO cross-linking agent, if the vulcanization method involving air (oxygen) as described above is used, severe surface adhesion occurs and the product does not become a product. It was applied and its application range was limited.

  On the other hand, as a technique for improving the tackiness of the crosslinked surface in the continuous crosslinking of EPDM, a) a method of blending a silicone rubber and a bismaleimide compound, b) a method of using EPDM having a very high ethylene content, c) a diene A method using DCDP-EPDM copolymerized with DCDP as a component, and d) a method of blending a large amount of liquid polybutadiene are proposed.

  However, when these techniques are applied, the physical properties of rubber products may be adversely affected, and the degree of freedom in material design is extremely limited, which is insufficient for industrial application. Therefore, for the continuous production of PO cross-linked material, a method is adopted in which oxygen does not touch the rubber surface. For example, electric wires are produced in large continuous cross-linking devices in which oxygen is replaced with nitrogen. Moreover, although it is difficult to handle and includes environmental problems, a method using LCM (Liquid Curing Medium) crosslinking using molten nitrate as a medium is applied.

  When a material using a PO crosslinker is cross-linked in the presence of air, polymer radicals generated by hydrogen abstraction by the PO crosslinker are combined with oxygen in the air, causing the rubber molecules on the surface of the product to be cut, resulting in significant adhesion to the surface. Cause it to occur. Moreover, the inside is accompanied by the generation of voids seen during the crosslinking reaction. Therefore, with the exception of some silicone rubbers, crosslinking under hot air with a PO crosslinking agent has been considered impossible.

As a result of intensive studies, the inventors have been able to continuously crosslink under hot air by a new processing method in which a sulfur suspension is sprayed before the crosslinking step of applying temperature, and then heat is applied to obtain a crosslinked rubber continuously. Technology was developed (Patent Documents 1 to 3). However, as a result of subsequent studies, it has been found that the crosslinking density tends to be lower than that of the molded crosslinked rubber, and a material having a high crosslinking density is required in the extrusion process. In particular, in order to obtain the target product hardness, it has been found that there is a problem that a large amount of PO cross-linking agent is required or EPDM having a higher molecular weight than necessary is applied, and that it is difficult to process.
JP 2001 213973 A Japanese Patent Laid-Open No. 2005-133090 JP 2005 139293 A

  The object of the present invention is a continuous organic peroxide having good extrusion processability, good mechanical strength, no tackiness on the surface of the cross-linked product, no problem at all, and high cross-linking density It is to provide a method for processing a crosslinked rubber molded body and a crosslinked rubber molded body obtained by the processing method.

The processing method of the crosslinked rubber molded product of the present invention and the crosslinked rubber molded product obtained by the processing method are provided by the matters described in [1] to [5] below.
[1] (A) 100 parts by weight of ethylene / α-olefin / non-conjugated diene copolymer rubber (B) Intrinsic viscosity [η] (measured with a 135 ° C. decalin solution) is 0.15 to 0.8 dL / g (AB) 100 parts by weight of ethylene / α-olefin copolymer rubber obtained by mixing 20 to 120 parts by weight of a certain liquid ethylene / α-olefin copolymer rubber,
(C) 1 to 20 parts by weight of an organic peroxide,
(D) Compound viscosity of (G) ethylene / α-olefin copolymer rubber composition containing 20 to 350 parts by weight of carbon black and / or white filler, and (E) 0.01 to 200 parts by weight of softener. In a processing method for a crosslinked rubber molded product obtained from the composition having a Mooney viscosity ML1 + 4 @ (100 ° C.) of 15 to 180, the crosslinking density M1 of the crosslinked rubber molded product obtained from the rubber composition (G) And the ratio (M1 / M2) of the crosslinked rubber molded body obtained from the ethylene / α-olefin copolymer rubber composition (B) having the same compound viscosity and not containing the copolymer rubber (M1 / M2). and 120% or more, and uncrosslinked composition surface sulfur suspension was applied to a continuous crosslinked rubber molded, characterized in that the organic peroxide crosslinking in the presence air prior to crosslinking Processing method to.
[2] The processing method according to [1], wherein the ethylene content of the (B) ethylene / α-olefin copolymer rubber according to [1] is 30 to 79 mol%.
[3] The processing method according to [1] or [2], wherein the ethylene content of the (A) ethylene / α-olefin / non-conjugated diene copolymer rubber described in [1] is 30 to 79 mol% .
[4] The (A) ethylene / α-olefin / non-conjugated diene copolymer rubber and the (B) ethylene / α-olefin copolymer rubber described in [1] are both polymerized using a metallocene catalyst. The processing method according to any one of [1] to [3].
[5] A crosslinked rubber molded article obtained by the processing method according to any one of [1] to [4].

  According to the present invention, a continuous organic peroxide having good extrudability, good mechanical strength, no tackiness on the surface of the cross-linked product, no problem at all, and high cross-linking density A method for processing a crosslinked rubber molded body and a crosslinked rubber molded body obtained by the processing method are obtained.

1) (A) Copolymer rubber (A) (A) Ethylene / α-olefin / non-conjugated diene copolymer rubber (hereinafter abbreviated as (A) copolymer) used in the present invention is composed of ethylene and carbon atoms. It is a copolymer of a 3 to 20 α-olefin and a non-conjugated polyene.

  The α-olefin having 3 to 20 carbon atoms is not particularly limited, and for example, α-olefin having 3 to 10 carbon atoms such as propylene, 1-butene, 1-hexene, 1-octene is preferable, and most preferably Propylene.

  The non-conjugated polyene is a non-conjugated polyene having 2 or more, preferably 2 carbon-carbon double bonds in one molecule. Specific examples of the double bond include a double bond existing at the end of a chain hydrocarbon, such as a double bond existing in a vinyl group or an allyl group, and a double bond existing in an alicyclic hydrocarbon ring. Examples thereof include a double bond that is not conjugated. Such non-conjugated polyenes do not include chain polyenes whose both ends are vinyl groups. When one of the two or more vinyl groups is a terminal vinyl group, the other vinyl group is preferably not an end but an internal olefin structure.

  Examples of the non-conjugated polyene include aliphatic polyene and alicyclic polyene. As the alicyclic polyene, a polyene composed of an alicyclic portion having one unsaturated bond and a chain portion containing a carbon-carbon double bond is preferable. Specifically, dicyclopentadiene, 5 -Ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5-methylene-2-norbornene and the like, and particularly preferred is a norbornene compound having a substituent containing a carbon-carbon double bond. Non-conjugated polyenes can be used singly or in combination of two or more.

  The upper limit of intrinsic viscosity [η] (measured with a 135 ° C. decalin solution) is not particularly limited, but is 10 dL / g from the viewpoint of workability, and the lower limit is 0.9 dL / g. From the workability, it is preferably in the range of 1.0 to 6.0 dL / g.

  The ethylene content is preferably 30 to 79 mol%, and most preferably in the range of 40 to 78 mol%. If it is less than 30 mol%, the heat aging resistance is poor, and if it exceeds 79 mol%, the low-temperature flexibility tends to deteriorate, such being undesirable.

  The content of the non-conjugated polyene is 1 wt% to 20 wt% in view of workability and the characteristics of the crosslinked rubber molded product. When it is smaller than the range, the crosslinking density is lowered, and when it is larger, the heat aging resistance tends to deteriorate.

2) (B) Copolymer rubber (B) Liquid ethylene / α- used in the present invention having an intrinsic viscosity [η] (measured with a decalin solution at 135 ° C., the same applies hereinafter) of 0.15 to 0.8 dL / g The olefin copolymer rubber (hereinafter abbreviated as (B) copolymer) is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.

  The α-olefin having 3 to 20 carbon atoms is the same as the (A) copolymer rubber. The ethylene content is preferably 30 to 79 mol%, more preferably 30 to 75 mol%, and most preferably 40 to 70 mol% within the range. When it is less than 30 mol%, the heat aging resistance is deteriorated, and when it is higher than 79 mol%, a high crosslinking density may not be obtained.

  The intrinsic viscosity [η] (measured with a 135 ° C. decalin solution) is in the range of 0.15 to 0.8 dL / g. If it is less than that, it is difficult to increase the crosslink density, which is an effect of the invention. A more preferable range is 0.20 to 0.60 dL / g.

  The amount of the (B) copolymer rubber is 20 to 120 parts by weight, preferably 30 to 100 parts by weight, based on 100 parts by weight of the (A) copolymer rubber. When the amount is less than 20 parts by weight, an improvement in the crosslinking density cannot be expected. If it exceeds 120 parts by weight, the crosslinked rubber may become sticky.

3) Polymerization catalyst and polymerization conditions In the production of (A) copolymer rubber and (B) copolymer rubber used in the present invention, there are no particular limitations on the polymerization catalyst and polymerization conditions. As the polymerization catalyst, various conventionally known catalysts such as a Ziegler-Natta catalyst, a metallocene catalyst, an imine catalyst, and a phenoxyimine catalyst can be used. Most preferably, it is a metallocene catalyst. As for the polymerization method, for example, conventionally known polymerization methods such as solution polymerization, slurry polymerization, and bulk polymerization can be employed. Specifically, for example, each monomer is continuously supplied into the reactor, the copolymerization reaction is allowed to proceed at a predetermined temperature in the presence of a catalyst, the obtained copolymer rubber is separated and dried, and then ( G) It uses for adjustment of a copolymer rubber composition.

4) (G) Composition The (G) ethylene / α-olefin copolymer rubber composition (hereinafter abbreviated as (G) rubber composition) used in the present invention is composed of (A) copolymer rubber and (B) copolymer. (AB) 1 to 20 parts by weight of an organic peroxide, (D) carbon black, based on 100 parts by weight of (AB) ethylene / α-olefin copolymer rubber obtained by mixing polymer rubbers as main components And / or 20 to 350 parts by weight of a white filler and (E) 0.01 to 200 parts by weight of a softener.

  (G) The compound viscosity (Mooney viscosity; ML1 + 4 @ (100 ° C.)) of the rubber composition is 15 to 180. If it is less than that, it will be difficult to produce a product because the extruded shape is greatly deformed. Exceeding that makes extrusion difficult. A more preferable range is 30 to 130.

  (C) Although there is no restriction | limiting in particular in the kind of organic peroxide, As a specific example, di-t-butyl peroxide, di-t-amyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butyl) Dialkyl peroxides such as peroxy) hexyne-3; 2,2-bis (t-butylperoxy) octane, n-butyl-4,4-di-t-butylvalerate, 1,1-bis (t -Peroxyketals such as butylperoxy) cyclohexane and 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, and the like One or more in can be used. In particular, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 1,3-bis ( Dialkyl peroxides such as t-butylperoxyisopropyl) benzene, t-butylcumyl peroxide and dicumyl peroxide are preferably used.

  (D) Carbon black is not particularly limited in its type, but specific examples include those belonging to IISAF-HS, HAF-HS, MAF and part of FEF in international classification, and the product name is Seast 3H. Diamond Black SH, Seast 116, Niteron # 10, Asahi # 60H, Asahi # F200, and the like.

  The white filler used together with the carbon black or alone is not particularly limited in its type, but specific examples include various silicates such as wet and dry silica, clay, talc, wollastonite, calcium carbonate, Examples of the surface treatment filler include carbonates such as magnesium carbonate, metal oxides such as zinc oxide, aluminum oxide, and titanium oxide, and coupling agents thereof, and clay, talc, silica, and silicate are particularly preferable.

  (E) There are no particular restrictions on the type of softener, but specific examples include synthetic polymer systems such as paraffinic process oil, naphthenic process oil, lubricating oil, paraffins, liquid paraffin, silicone oil, and liquid polybutene. Examples include softeners and ester plasticizers such as phthalic acid, adipic acid, and sebacic acid. Of these, paraffinic process oil is preferred.

  The compound viscosity (Mooney viscosity ML1 + 4 @ (100 ° C.)) of the composition (G) used in the present invention is 15 to 180. If it is less than that, excellent processability is not obtained, and it is difficult to obtain a crosslinked rubber molded product.

  (G) Crosslink density M1 of the crosslinked rubber molded product obtained from the copolymer rubber composition and the same compound viscosity, for example, (B) all or one of the copolymer rubbers added to the G copolymer rubber composition The ratio (M1 / M2) of the crosslinked rubber molded body in which the part is replaced with paraffin oil or the like with the crosslinking density M2 is 120 or more. A continuous organic peroxide crosslinkable composition that satisfies it is obtained. In addition, a molded product having physical properties of a crosslinked rubber molded product obtained by molding and inferior crosslinked rubber can be obtained. Accordingly, it is not necessary to add a large amount of PO crosslinking agent in order to increase the crosslinking density, and it is not necessary to use a higher molecular weight polymer than necessary.

  The (G) copolymer rubber composition used in the present invention is a kneading known from the copolymer rubber of the present invention and other components, such as a Banbury mixer, kneader, roll, uniaxial or biaxial extruder. It can be prepared by kneading at a predetermined temperature using a machine.

  The rubber composition (G) used in the present invention contains (A) copolymer rubber and (B) copolymer rubber described above as main components. The other components are not particularly limited, and various conventionally known additive components such as rubber reinforcing agents, fillers, anti-aging agents, processing aids, vulcanizing agents, vulcanization accelerators, vulcanizing aids, flame retardants. Etc. can be blended within a range not impairing the object of the present invention. Further, commercially available rubbers other than (A) copolymer rubber and (B) copolymer rubber may be added.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. The physical property measuring methods in the examples and comparative examples are as follows. In addition, unless otherwise indicated, the part and% in an Example are a basis of weight.

[1] Evaluation method 1) Mooney viscosity (compound viscosity is the same)
The Mooney viscosity (ML1 + 4, 100 ° C.) of the compounded rubber was measured according to JISK6300.
2) Evaluation of surface adhesion After taking out the crosslinked rubber from the HAV vulcanizing tank using a take-up machine, after confirming that the surface temperature reached 170 ° C. with a surface thermometer, it was strongly scratched with a soft iron needle (tip diameter 100 μm) about 5 cm, The states were classified and evaluated as follows.
E: No scratches and no traces. There are no voids. There is no adhesion.
G: There is a slight scratch mark. There are no voids. There is no sticking F; there is a slight scratch mark. There are many voids. Slightly sticky.
P: There are some scratches. There are many voids. Slightly sticky.
VP; There is a deep wound. There are countless voids. There is terrible adhesion.
3) Crosslink density measurement The sample was swollen in a toluene solvent at 37 ° C for 72 hours to obtain an equilibrium swollen state, and then the change in weight was determined. The number of crosslinks per cubic meter was determined according to the Flory-Rehner equation.
4) Tensile test, hardness test The obtained crosslinked sheet was measured according to JIS K6301.

[2] Preparation of Sulfur Suspension A sulfur suspension was prepared by the method described in Japanese Patent Application Laid-Open No. 2005-139293 of Patent Document 3. Specifically, distearyldimethylammonium chloride, which is a cationic surfactant, was used as a dispersant. A 500 mL four-flask equipped with a nitrogen inlet, a thermometer, and a propeller type worship machine was placed on a water bath, nitrogen was introduced into the flask, and 262.5 g of purified water and As the dispersant, 6 g of polyoxyethylene lactyl ether, which is a nonionic surfactant, was added, and the disperser was dissolved by turning the chapel machine. When the dispersant is dissolved, 30 g of colloidal sulfur (which can pass through a 300-mesh node) and 1.5 g of a 10% by weight aqueous solution of polyvinyl alcohol (fully saponified type, degree of polymerization 1700) as a stabilizer are contained in the flask. Added to. While keeping the temperature in the flask at 30 ° C. or lower, the mixture was continuously aged for 5 hours with a worship machine to sufficiently disperse the colloidal sulfur to obtain a sulfur suspension for rubber crosslinking.

[3] Continuous cross-linking molding line processing The equipment of the continuous cross-linking molding line used was arranged in series in the order of a φ60 mm rubber extruder, a sulfur spraying device, a UHF vulcanizing tank, and a HAV vulcanizing tank. The take-up was performed at a speed of 3.5 m / min and the molding was performed for 5 minutes. The UHF vulcanization tank temperature was 230 ° C., the output was 2 kW, and the HAV vulcanization tank temperature was 250 ° C. A sulfur spraying device manufactured by Spraying Co., Ltd. is installed between the rubber extruder and the UHF vulcanizing tank, and the sulfur suspension is uniformly distributed over the entire surface of the extruded unvulcanized rubber (thickness 2mm, width 25mm). Applied. The spray amount of the sulfur suspension was 5 × 10 −5 m 3 / min, and 0.6 g / m 2 was applied on the surface of the extruded rubber. The method of use is the same as that described in Japanese Patent Laid-Open No. 2005-133090 of Patent Document 2.

[Examples 1 to 5 and Comparative Examples 1 to 10]
Table 1 shows various ethylene / propylene rubbers obtained by known methods. Table 2 shows various liquid ethylene / propylene rubbers obtained by known methods. Add zinc oxide, stearic acid, filler, etc. to them, knead for 6 minutes with a 16 liter internal mixer, add organic peroxide, carbon black, and softener and knead with a 14-inch roll. The compounded rubber sheet was dispensed. After that, it was continuously crosslinked at 250 ° C. for 5 minutes in a UHF and HAV continuous crosslinking tank to obtain a continuous crosslinked sheet having a thickness of 2 mm. The results are shown in Tables 3 and 4.

  The new and useful processing method according to the present invention can be widely used as a processing method for various rubber products. The crosslinked rubber molded product obtained by the processing method of the present invention has good extrudability, exhibits good mechanical strength, has no tack on the surface of the crosslinked product, has no problem at all, and has high crosslinking. Because of its density, automotive water hoses, window frames, door seal sponges, trunk lids, laminated extruded rubber products of solid rubber and sponge rubber, glass run channels, various other weather strips, building material gaskets, waterproof sheets, Used for rubber products manufactured by extrusion molding of EPDM such as roofing and electric wires.

Claims (5)

(A) 100 parts by weight of ethylene / α-olefin / non-conjugated diene copolymer rubber (B) liquid having an intrinsic viscosity [η] (measured with a 135 ° C. decalin solution) of 0.15 to 0.8 dL / g (AB) 100 parts by weight of ethylene / α-olefin copolymer rubber obtained by mixing ethylene / α-olefin copolymer rubber in a weight ratio of 20 to 120,
(C) 1 to 20 parts by weight of an organic peroxide,
(D) Compound viscosity of (G) ethylene / α-olefin copolymer rubber composition containing 20 to 350 parts by weight of carbon black and / or white filler, and (E) 0.01 to 200 parts by weight of softener. In the method of processing a crosslinked rubber molded product obtained from the composition having a Mooney viscosity ML1 + 4 @ (100 ° C.) of 15 to 180, the crosslinking density M1 of the crosslinked rubber molded product obtained from the (G) rubber composition And the ratio (M1 / M2) of the crosslinked rubber molded body obtained from the ethylene / α-olefin copolymer rubber composition (B) having the same compound viscosity and not containing the copolymer rubber (M1 / M2). and 120% or more, and uncrosslinked composition surface sulfur suspension was applied to a continuous crosslinked rubber molded, characterized in that the organic peroxide crosslinking in the presence air prior to crosslinking Processing method to.   2. The processing method according to claim 1, wherein the ethylene content of the (B) ethylene / α-olefin copolymer rubber is 30 to 79 mol%.   3. The processing method according to claim 1 or 2, wherein the ethylene content of the (A) ethylene / α-olefin / non-conjugated diene copolymer rubber is 30 to 79 mol%.   The (A) ethylene / α-olefin / non-conjugated diene copolymer rubber and the (B) ethylene / α-olefin copolymer rubber according to claim 1 are both polymerized using a metallocene catalyst. 4. The processing method according to any one of 3.   A crosslinked rubber molded product obtained by the processing method according to claim 1.