JPS6151038A - Sponge rubber composition - Google Patents

Abstract

PURPOSE:The titled compsn. excellent in workability during preparation, sealing properties, and door-opening and closing properties and having little temp.-dependence of sponge, which is prepd. by incorporating a copolymer rubber obtd. by copolymerizing ethylene, alpha-olefin and a specified diolefin. CONSTITUTION:70-40wt% ethylene, 30-60% 3-12C alpha-olefin and diolefin consisting of ethylidenenorbornene and dicyclopentadiene in a ratio of 1:1-6:1 (in iodine value) and giving iodine value of 15-45 to the copolymer rubber to be prepd. are copolymerized in a polymn. solvent in the presence of a catalyst to obtain ethylene/alpha-olefin/diolefin copolymer rubber with mooney viscosity of 55- 110 ML1+8 (120 deg.C) and a weight-average ML/number-average ML ratio of 2-10 contg. 3-15wt% cyclohexane insolubles at 30 deg.C. Then 100pts.wt. said copolymer rubber, 50-200pts.wt. filler, 30pts.wt. or more softening agent, 0.5-20pts.wt. blowing agent (or auxiliary), 0.5-10pts.wt. crosslinking agent, etc. are compounded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a sponge rubber composition containing an ethylene-α-olefin-diolefin copolymer rubber as an essential component, which has excellent processability, sealability, and low-temperature properties.

Traditional technology Much of the demand for sponge rubber is used in automotive applications,
Specifically, it is used around doors, trunks, etc.
Used to seal against water, sound, etc.

Conventionally, natural rubber, chloroprene rubber, styrene-butadiene copolymer rubber, etc. have been used as base materials for such sponge rubber, but ethylene-α-olefin has been used because of its excellent weather resistance, heat resistance, and light weight. -Diolefin copolymer rubber (hereinafter sometimes referred to as rEPDMJ for cars)
has attracted attention, and is now being almost completely replaced by EP-DM.

Problems to be solved by the invention - However, the demands on automobiles are becoming more sophisticated.

Along with this, the requirements for the sponge rubber used therein are also becoming more sophisticated, and it is becoming difficult to provide sufficiently satisfactory sponge rubber using conventional technology.

In particular, as expressway networks have been developed not only in Europe and the United States, but also in Japan, and opportunities for automobiles to travel at high speeds for long periods of time have increased, demand for lightweight sponge rubber with excellent sealing properties against noise and water has already increased. It can even be said to be a social need.

Further, the characteristics of the sponge rubber must be maintained under various temperature conditions from low to high temperatures, and the sponge rubber must also be soft so that the door can be opened and closed smoothly.

On the other hand, various requirements must be met in the process of manufacturing such sponge rubber.

That is, it is required to have excellent processability in a Banbury mixer, roll mill, extruder, etc., to not lose its shape during vulcanization, and to be inexpensive to manufacture.

Conventionally, for example, in Japanese Patent Publication No. 5B-57450, the ethylene content was 55 to 73 mol%, the product of the maximum tensile stress and the elongation at break of the copolymer rubber was 7 x 103 or more, and the Mooney viscosity was 4,121℃) is 65~
120 has been shown to have excellent processability and shape deformability, but even if this copolymer rubber is used, the balance between processability, cold resistance, and sealability, especially in terms of cold resistance, is insufficient. Sponge rubber is not available.

In addition, a sponge rubber with excellent foaming properties and processability has been proposed, which is made of an ethylene-α-olefin-ethylidenenorbornene-synchropentadiene quaternary copolymer.
Generally, the molecular weight distribution is set widely, so there is no material that is fully satisfactory in terms of low-temperature properties and sponge strength.

The present invention consists of 1. This product was developed in response to the above-mentioned conventional technical problems, and uses ethylene-α-olefin-diolefin copolymer rubber, which has excellent processability during manufacturing, is lightweight, has excellent sealing properties, and door opening/closing properties. Another object of the present invention is to provide a composition capable of obtaining a sponge rubber whose sponge properties are less dependent on temperature.

A means for solving the problems, that is, the present invention is a sponge rubber composition characterized by using an ethylene-α-olefin-diolefin copolymer rubber that satisfies the following conditions (a) to (e). be.

(a) α-olefin has 3 to 12 carbon atoms, ethylene/
α-olefin is 70-40/30-60° (b) Diolefin is composed of ethylidene norbornene and synchropentadiene, the amount of unsaturation in the copolymer rubber is 15-45 in terms of iodine value, and ethylidene The iodine side ratio of norbornene and synchropentadiene is 1:1 to 6:
1゜(c) Mooney viscosity of copolymer rubber (MLl.6.120
°C) is 55 to 110 °C. (d) When the copolymer rubber is dissolved in cyclohexane at 30 °C, the undissolved amount is 3 to 15% by weight.

(e) Weight average molecular weight it (Mw) and number average molecular weight (Mn
) ratio (M w / M n) of 2 to 10°. ) must satisfy the conditions (a) to (e) above.

(a) α- used as monomer for copolymerization of copolymer rubber
The olefin is an α-olefin having 3 to 12 carbon atoms, and specific examples include propylene, butene-1,4-methylpentene-1, hexene-1, and octene-1. Preferred is propylene. These α-olefins can be used alone or in combination of two or more.

The weight ratio of ethylene/α-olefin in the copolymer rubber is 70 to 40/30 to 60, preferably 65 to 45.
/35 to 55.

If the ethylene content in the copolymerized rubber exceeds 70% by weight, the fluidity deteriorates, resulting in wasted energy being required during cross-crossing, and processability problems such as worsening of the raw rubber being bitten into rolls and extruders. This also causes a decrease in the cold resistance of the sponge rubber. On the other hand, the ethylene content is 40% by weight.
If it is less than that, the filler will not be sufficiently dispersed, the surface of the sponge rubber will become rough, the sealing properties will deteriorate, and the strength of the sponge rubber will fall below the practical range.

(b) The diolefin component of the copolymer rubber of the present invention includes ethylidenenorbornene (hereinafter sometimes simply referred to as rENBJ) and synchropentadiene (hereinafter simply referred to as rENBJ).
(sometimes referred to as DcPDJ) must be used in combination.

In either case of using ENB alone or DCPD alone as the diolefin, the balance between vulcanization and foaming is lost, making it impossible to obtain a highly foamed and soft sponge rubber. The copolymer rubber used in the present invention has excellent cold resistance, probably because the ethylene sequence distribution is different from that of a single system by using ENB and DCPD in combination to form a quaternary EPDM.

Furthermore, blend systems of ENB-based EPDM and DCPD-based EPDM have the problem of complicated quality control during the manufacturing process, and are more difficult to vulcanize than quaternary EPDM, in which ENB and DCPD exist in the same polymer chain. Perhaps because the foaming conditions are different, problems arise with the surface texture and feel of the sponge rubber.

The amount of unsaturation of the diolefin in the copolymer rubber is 15 to 45, preferably 20 to 40 in terms of iodine value, and EN
The iodine side ratio of B and DCPD is 1:1 to 6:1, preferably 2:1 to 5:1.

If the total amount of unsaturation is less than 15 in terms of iodine value, the obtained sponge rubber will not be highly foamed, and the rubber will not have sufficient mechanical strength and cold resistance. On the other hand, when the iodine value exceeds 45, high foaming cannot be achieved and the desired sponge rubber cannot be obtained.

Furthermore, if the ratio of iodine between ENB and DCPD is less than 1:1 or greater than 6:1, the balance between vulcanization and foaming is lost, and the desired sponge rubber cannot be obtained.

(c) Mooney viscosity of copolymer rubber (MLl+6, 120
C) is 55-110, preferably 70-95.

If the Mooney viscosity is less than 55, the sponge strength will be insufficient, while if it exceeds 110, the kneading properties will deteriorate.

(d) When the copolymer rubber is dissolved in cyclohexane at 30°C, the amount of insoluble matter must be 3 to 15% by weight.

If the cyclohexane insoluble content is less than 3% by weight, it will lead to deterioration of kneading properties, roll workability, and extrusion surface texture, and if it exceeds 15% by weight, the cold resistance of the resulting sponge rubber will deteriorate. The problem arises.

These phenomena occur because the cyclohexane insoluble amount is mainly composed of crystalline components based on long chain length components of ethylene.

(e) The ratio of the 1Rffi average molecular weight (M w ) of the copolymer rubber to the number average molecular weight ii (Mn) determined from gel permeation chromatography (GPC) measured at 120°C in orthodichlorobenzene (M w /Mn)
must be between 2 and 10, preferably between 3.5 and 8.5.

When Mw/Mn is less than 2, processing problems such as kneading properties in a Banbury mixer and winding properties in a roll mill occur.

On the other hand, when M w /M n is greater than 10, there is no problem in processing, but the centrifugal properties and strength of the sponge rubber deteriorate mainly due to the influence of low molecular weight components.

The sponge rubber composition of the present invention contains a copolymer rubber satisfying the conditions (a) to (e) above as an essential component, and contains various additives and other rubbers described below. The content ratio is at least 20% by weight in the composition,
Preferably it is 20 to 60% by weight.

If the amount of copolymer rubber is less than 20% by weight based on the composition, the obtained sponge rubber will not have the above-mentioned properties aimed at by the present invention.

The copolymer rubber that satisfies the conditions (a) to (e) above is composed of at least one organometallic compound selected from groups ■ to ■ of the periodic table, and at least one type of organometallic compound selected from groups It is produced using a catalyst consisting of a combination of at least one selected transition metal compound.

As such an organometallic compound, an organoaluminum compound is suitable, and specifically, triethylaluminum,
At least one member may be selected from triisobutylaluminum, diethylaluminium chloride, diisobutylaluminum chloride, sesquiethylaluminum chloride, ethylaluminum dichloride, isobutylaluminum dichloride, n-octylaluminum dichloride, etc., and trialkylaluminum is preferably selected. and sesquialkyl aluminum.

Further, as the transition metal compound, vanadium compounds and titanium compounds are suitable, and specifically vanadium oxytrichloride, alkoxyvanadate, mixtures of vanadium oxytrichloride and saturated aliphatic alcohols having 1 to 12 carbon atoms, Xa--T i (OR) I, l (wherein X: halogen, OR: alkoxy group having 1 to 12 carbon atoms, m:.

At least 1 from the titanium compounds represented by
It is sufficient to select one or more types, and preferably a mixture of a vanadium compound and a titanium compound.

Using the catalyst as described above, for example, normal hexane is used as the polymerization solvent, the polymerization temperature is -10 to 50 °C, and the pressure is 0 to 10 k.
Ethylene, alpha-olefin, ethylidene norbornene and synchlopentadiene are contacted in a range of g/caf. Molecular weight can be adjusted using hydrogen gas.

If the Mooney viscosity is high, it can also be finished as an oil-extended rubber.

Ethylene-α-olefin used in the present invention
Diolefin copolymer rubber is manufactured into sponge rubber by blending fillers, softeners, blowing agents, crosslinking agents, etc. as necessary to make a sponge rubber composition, and then foaming and crosslinking according to commonly used methods. Ru.

Fillers that can be mixed include inorganic fillers such as carbon black, particulate silicic acid, calcium carbonate, magnesium carbonate, clay, and talc, and organic fillers such as fiber flock, but inorganic fillers are generally preferred. used.

The amount of filler added is 5 parts by weight per 100 parts by weight of the copolymer rubber.
It is often used in a range of 0 to 200 parts by weight.

Examples of softeners include aromatic oils commonly used in rubber, so-called process oils such as naphthenic oil and paraffin oil, and vegetable oils such as coconut oil. Preferably, process oil is preferred (among which paraffin oil is particularly preferred).

Addition of the softener (2) is used in an amount of 30 parts by weight or more based on 100 ifi parts of the copolymer rubber.

As blowing agents, inorganic blowing agents such as ammonium carbonate, sodium bicarbonate, anhydrous sodium nitrate, dinitrosopentamethylenetetramine, N,N'dimethyl-N,N'
-Dinitrosoterephthalamide, benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, p+
p'-oxybis(benzenesulfonylhydrazide),
3.3'-disulfone hydrazide diphenyl sulfone,
Organic blowing agents include azobisisobutyronitrile and azobisformamide.

Also, along with foaming agents, urea-based, organic acid-based, and metal salts are used.

Foaming aids of various types can be used.

The foaming aid is used together with a foaming agent having a high decomposition temperature, such as dinitrosopentamethylenetetramine or azodicarbonamide, and is added for the purpose of appropriately lowering and adjusting the foaming temperature. Specific examples include Selton N (Sankyo Kasei Q !!!), Cellbase M3 (manufactured by Hydration Kasei ■)
and so on.

The amount of the foaming agent and foaming aid added is 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, and 0 to 20 parts by weight of the foaming aid to 100 parts by weight of the copolymer rubber. range.

As a crosslinking agent, powdered sulfur, precipitated sulfur, colloidal sulfur,
Sulfur such as insoluble sulfur, sulfur chloride, selenium, tellurium, thiuram disulfides, dithiodimorpholine,
1.1-di-tert-butylperoxy-3,3,
5-) Limethylcyclohexane, di-tert-butyl peroxide, dicumyl peroxide tert-butylcumyl peroxide, 2゜5-dimethyl-2
, 5-di(butylperoxy)hexane,
Peroxides such as 1,3-bis-(tert-butylperoxy-isopropyl)benzene, preferably sulfur, peroxides, especially sulfur, 1,1-di-tert-butylperoxy-3 , 3,5-trimethylcyclohexane, di-tert-butyl peroxide, and dicumyl peroxide.

When sulfur is used as a crosslinking agent, aldehyde ammonias such as hexamethylenetetramine, guanidines such as diphenylguanidine, di-ortho-tolylguanidine, ortholyrubiguanidine, di-ortho-tolylguanidine, dicaracol boron salt, thio Thioureas such as carbamide, di-ortho-tolylthiourea, N,N'-diethylthiourea, tetramethylthiourea, 2-mercaptoimidacillin, trimethylthiourea, mercaptobenzothiazole, N-tert-butyl-2-
Benzothiazole sulfenamide, N,N'-dicyclohexyl-2-benzothiazoyl sulfenamide, dibenzothiazyl disulfide, 2-(4-morpholinodithio)benzothiazole, 2-(2゜4-dinitro phenyl)-mercaptobenzothiazole, N,N'-diethylthiocarbamoyl-2-benzothiazoyl alphide, N,N'-diisopropyl-2-benzothiazolesulfenamide, N-cyclohexyl-2-benzothiazole Thiazoles such as azilsulfenamide, N-oxydiethylene-2-benzothiazolesulfenamide, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc di-n-butyldithiocarbamate,
Dithiocarbamates such as zinc ethylphenyldithiocarbamate, lead ethylphenyldithiocarbamate, sodium dimethyldithiocarbamate, diethylthiocarbamoyl, diethyldithiocarbamate, selenium rubamate, tellurium diethyldithiocarbamate, piperazine-bis-(0゜0'-di xanthates such as stearyl dithiophosphate), thiurams such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide, etc., or a combination of two or more. It can be used as a crosslinking accelerator.

In addition, in crosslinking with peroxides, sulfur, p-quinonedioxime, p,p'-dibenzoylquinonedioxime, lauryl methaflerate, ethylene glycol acrylate, trimethylolpropene trimethacrylate, diaryl phthalate, triallyl cyanurate It is also possible to add crosslinking aids such as. Other crosslinking accelerators, such as zinc white, magnesium oxide, litharge, red lead, white lead, stearic acid, oleic acid, zinc stearate, organic amines such as Acting (manufactured by Yoshitomi Pharmaceutical), and phthalic anhydride. m-acid: 6L A nitroso compound such as N,N'-nitrodiphenylamine can be added.

- The amount of the bridging agent added is 0.00 parts by weight per 100 parts by weight of ethylene-α-olefin-diolefin copolymer rubber.
It is used in a range of 5 to 10 parts by weight.

The crosslinking accelerator may be used in an amount of 0.1 to 10 parts by weight, and an anti-aging agent and other additives commonly used in rubber may be added in any proportion.

We also use other types of rubbers such as butyl rubber, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, and different types of rubber such as Mooney viscosity, copolymer composition, molecular weight distribution, etc. It can also be used in combination with ethylene-α-olefin copolymer rubber.

Other rubbers that are mixed into the copolymer rubber in the production of sponge rubber in the present invention: 1. The blending ratio, blending method, and blending order of fillers, softeners, foaming agents, and crosslinking agents are not particularly limited, but the copolymer rubber, other rubbers, fillers, softeners, etc. may be mixed using a Banbury mixer or the like. After mixing, a blowing agent, blowing aid, crosslinking agent, etc. are added using a roll or the like.

Next, foaming and crosslinking is performed by placing it in a mold and increasing the temperature using the method used for normal sponge rubber manufacturing, or it is molded into an arbitrary shape using an extrusion molding machine and heated in a crosslinking tank. Sponge rubber can be produced by foaming and crosslinking.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the Examples unless it exceeds the scope of the claims.

In the Examples, various analysis methods and physical property measurement methods were conducted in accordance with the following methods.

(i) Propylene content measured by infrared absorption spectrum (ii) Iodine value measured by infrared absorption spectrum (iii) Mooney viscosity (ML+-s, 120°C)
Preheat for 1 minute, measure for 8 minutes, and measure at a temperature of 120°C (iv)
250 cm of raw rubber containing no cyclohexane-insoluble compounding agent was cut into pieces with a side length of 1 fi or less, immersed in 100 ml of cyclohexane, and kept in a constant temperature bath at 30° C. for 48 hours. Thereafter, it is filtered through an 80-mesh stainless steel wire mesh, and the undissolved bone is vacuum-dried at 105° C. for 1 hour, and then weighed. The value obtained by dividing this insoluble amount by the weight of the raw rubber is defined as the cyclohexane insoluble amount (wt%).

In the case of oil-extended rubber, it is corrected to the weight % based on the rubber component excluding oil.

(v) The processability of the compounded rubber in a Banbury mixer was evaluated by visually evaluating the state of the composition after being discharged from the Banbury in terms of filler mixing state, texture, and cohesion. The result is excellent.
Indicated as good, fair, poor, or poor.

(vi) The roll processability of the compounded rubber was determined by rolling the unvulcanized compound with a 10-inch roll at a roll temperature of 50°C ± 5°C.
It was wound around a roll with a nip width of 2 u, and evaluated based on the length of time required to tightly wrap it and whether it was wound tightly or not. Result is,
Indicated as excellent, good, fair, poor, or poor.

(vii) Regarding the sheet texture, after the roll processability test, the surface condition of the sheet sample was evaluated based on the smoothness, gloss, etc. of the surface texture. The results were shown as excellent, good, fair, poor, or poor.

(vii) Sponge Properties The samples used for measuring the following sponge properties were the sponge rubbers shown in Examples.

■Specific gravity Measured according to the Japan Rubber Association standard and physical test method for expanded rubber.

■Skin and feel of the skin were evaluated based on the smoothness, gloss, and non-stickiness of the sponge rubber surface.

The feel was evaluated based on the elasticity and softness when the sponge rubber was bent.

All results were shown as excellent, good, fair, poor, or poor.
' ■Tensile strength TB) Punch out a No. 3 dumbbell-shaped test piece from sponge rubber, and
Measured according to IS K6301.

■ Compression set according to JIS K6301, 5 in the direction of Figure 1 a-b.
Apply 0% compressive strain, -20℃×22 hours, +70℃×
Compression set after 22 hours was measured.

(ix) Mw/Mn Takeuchi, Gel Permeation Chromatograph, Maruzen 0
It was measured as follows according to Kikukan.

■Standard polystyrene with known molecular weight (manufactured by Toyo Soda 01,
Using monodisperse polystyrene), the molecule IM and its G
P C (Gel Permeation Chroma)
-tograph) counts, molecular weight M and EV
(Elution Volume) Plot a correlation diagram calibration curve. The concentration at this time is 0.02% by weight.

The standard polystyrene calibration curve is corrected to the EPDM calibration curve using the universal method.

■Take the GPC pattern of the sample using the GPC measurement method,
Know M from the above ■. The sample preparation conditions and GPC measurement conditions at that time are as follows.

Sample preparation (a) Antioxidant 2,6- in O-dichlorobenzene solvent
Add and dissolve 0.08% of tert-butyl-p-cresol.

(b) Separate the sample into an Erlenmeyer flask together with 0-dichlorobenzene solvent to a concentration of 0.1% by weight.
□ (C) Warm the Erlenmeyer flask to 120°C and stir for about 60 minutes.1. Dissolve.

(d) Subject the solution to GPC. Note that it is automatically filtered using a 0.5μ sintered filter within the GPC device.

GPC measurement conditions (a) Equipment Waters 150C type (b) Column Toyo Soda side H type (c) Sample amount 500μ
2 (d) Temperature: 120°C (e) Flow rate: 1 m lt /m1n (f) Total number of theoretical plates in column IXIQ' to 2X10' (measured value using acetone) Examples 1 to 4, Comparative Examples 1 to 9 Shown in Table 1 A rubber compound was prepared using the copolymer rubber according to the compounding recipe shown in Table 2.

The preparation method is to knead the ingredients CI) in Table 2 using a BR type Banbury mixer at a rotor rotation speed of 60 rpm and a temperature of 50°C for 5 minutes, and then mix the ingredients in Table 2 with a 10-inch roll maintained at 50°C. (n) was kneaded for 5 minutes.

The roll rotation speed is 22/28r for the front and rear rolls respectively.
It was pm.

The obtained rubber compound was formed into a molded product using a 50Φ1 extruder (guinea temperature: 80°C), and passed through a 200°C hot air tank for 5 minutes to obtain a sponge rubber.

The nozzle attached to the extruder is shown in Figure 1.

The properties of the obtained sponge rubber are shown in Table 3.

Table 1 *l ENB-based EP'DM and DCPD-based EPDM1:
1 blend (same properties except for iodine value) 2nd
Table *1 Mercaptobenzothiazole $2 2n-di-n-butyldithiocarbame-*32-
Mercaptoimidacillin *4 Dipentamethylene lentithuram tetrasulfide *5 Teryllium diethyldithiocarbamate *6p,
p'-oxybis(benzenesulfonylhydrazide) Effects of the Invention The sponge rubber composition of the present invention has excellent processability during production, is lightweight, has excellent sealing properties and door opening/closing properties, and has low temperature dependence of sponge properties. It is possible to provide sponge rubber, and its industrial significance is extremely large.

[Brief explanation of the drawing]

FIG. 1 shows the shape of a mouthpiece to be attached to an extruder used for molding unvulcanized rubber. Patent Applicant Japan Synthetic Rubber Co., Ltd. Agent Patent Attorney Shige Takashi Shirai Figure 1 (S position myzm)

Claims (1)

[Claims] 1. Ethylene-α that satisfies the following conditions (a) to (e):
- A sponge rubber composition characterized by using an olefin-diolefin copolymer rubber. (a) α-olefin has 3 to 12 carbon atoms, ethylene/
The weight ratio of α-olefin is 70-40/30-60. (b) The diolefin consists of ethylidene norbornene and synchropentadiene, the amount of unsaturation in the copolymer rubber is 15 to 45 in terms of iodine value, and the iodine value ratio of ethylidene norbornene to synchropentadiene is 1:1 to 6:1.
. (c) Mooney viscosity of copolymer rubber (ML_l_+_6,
120°C) is 55-110. (d) The amount of insoluble matter when the copolymer rubber is dissolved in cyclohexane at 30°C is 3 to 15% by weight. (e) Weight average molecular weight (Mw) and number average molecular weight (Mn)
The ratio (Mw/Mn) is 2 to 10.