JP2000017127A - Crosslinkable elastic copolymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition good in polyol curability and affording cured products of high resistance to heat and oil by including a specific copolymer, an organic quaternary phosphonium salt, an organic polyhydroxy compound, and a metal oxide and/or metal hydroxide. SOLUTION: This elastic copolymer composition comprises (A) 100 pts.wt. of an elastic copolymer composed of 35-65 mol.%, 20-50 mol.% and 0.5-15 mol.% of tetrafluoroethylene-based polymerization unit, propylene-based polymerization unit and vinylidene fluoride-based polymerization unit, respectively, (B) pref. 0.1-10 pts.wt. of a salt of a nitrogen-contg. heterocyclic compound and an organic quaternary phosphonium compound, (C) pref. 0.1-10 pts.wt. of one or more kinds of organic polyhydroxy compounds and derivatives thereof, and (D) pref. 1-50 pts.wt. of one or more kinds of metal oxide and metal hydroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinkable elastic copolymer composition having good vulcanizability of a polyol and obtaining a vulcanizate having good heat resistance and oil resistance.

[0002]

2. Description of the Related Art When an organic polyhydroxy compound is used as a vulcanizing agent, an elastic copolymer obtained by copolymerizing vinylidene fluoride (hereinafter referred to as VdF) exhibits good mold releasability and heat resistance. It is known to provide vulcanizates having excellent properties, oil resistance and compression set. The vulcanized product of this elastic copolymer is suitably used for automobile parts such as oil seals. However, with the improvement in engine oil performance, durability against engine oil containing a large amount of amine-based additives has been improved. Is an important issue. Particularly, a copolymer having a large content of polymerized units based on VdF, for example, a hexafluoropropylene (hereinafter, referred to as HFP) -VdF-based elastic copolymer, and an HFP-VdF-tetrafluoroethylene (hereinafter, referred to as TFE) -based elastic copolymer The vulcanized product of the composition containing the polymer has a problem that the degree of deterioration due to the reaction of the amine-based additive at the site of the polymerized unit based on VdF is large.

On the other hand, a vulcanized product of a composition containing a TFE-propylene (hereinafter referred to as “P”)-VdF-based elastic copolymer as a copolymer having a small content of polymerized units based on VdF is not resistant to engine oil. Excellent. By using organic quaternary ammonium hydrogen sulfate as a vulcanization accelerator, V
TF containing as little as 4 mol% of polymerized units based on dF
A good vulcanizate can be obtained even with an EP-VdF-based elastic copolymer (JP-A-6-157858). However, as can be seen in the examples, TF containing a large amount of polymerized units based on VdF can be obtained.
The vulcanization rate is lower than that of the EP-VdF-based elastic copolymer. If a relatively large amount of organic quaternary ammonium hydrogen sulfate is added to increase the vulcanization rate, the heat resistance and oil resistance of the vulcanized product may be adversely affected.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to provide Vd
TFE-P-VdF with low content of polymerized units based on F
An object of the present invention is to provide a crosslinkable elastic copolymer composition which contains a system elastic copolymer, has good polyol vulcanizability, and gives a vulcanizate having excellent heat resistance and oil resistance.

[0005]

The present invention provides (A) TFE
An elastic copolymer comprising 35 to 65 mol% of polymerized units based on P, 20 to 50 mol% of polymerized units based on P, and 0.5 to 15 mol% of polymerized units based on VdF,
(B) a salt of a nitrogen-containing heterocyclic compound and an organic quaternary phosphonium compound, (C) at least one selected from organic polyhydroxy compounds and derivatives thereof, and (D) selected from metal oxides and metal hydroxides. Provided is a crosslinkable elastic copolymer composition comprising at least one kind.

The Mooney viscosity ML which is an index of the molecular weight of the elastic copolymer of the component (A) in the composition of the present invention.
_{1 + 10} (121 ° C.) is not particularly limited, but is preferably in the range of 5 to 150, particularly 10 to 100 for kneading during the production of the composition.

TFE in elastic copolymer (A)
The proportion of the polymerized unit based on is preferably 35 to 65 mol% in order to provide good heat resistance and chemical resistance.
5 to 64 mol%. The proportion of polymerized units based on P is 2 to give a vulcanizate having good heat resistance and chemical resistance.
The content is 0 to 50 mol%, and more preferably 35 to 50 mol%. The proportion of polymerized units based on VdF is 0.5 to give a vulcanizate with very good engine oil resistance.
To 15 mol%, more preferably 0.5 to 10 mol%.

Accordingly, a preferred elastic copolymer in the present invention is such that the proportion of each polymerized unit of TFE, P and VdF is 45 to 64 mol%, 35 to 50 mol%,
The copolymer is 0.5 to 10 mol%.

The component (A) may or may not contain an unsaturated bond as an easily vulcanizable site in the copolymer. By simply heat-treating the component (A), or by heat-treating in the presence of a basic substance or an acidic substance,
HF can be removed from a polymerized unit based on dF to introduce a carbon-carbon unsaturated bond into the polymerized unit. An unsaturated bond can be similarly introduced by treating the aqueous dispersion of the component (A) obtained by polymerization with a basic substance such as potassium hydroxide. By introducing an unsaturated bond, (A)
It can improve the vulcanizability of the components.

For the production of the elastic copolymer (A), various polymerization systems such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization can be adopted. Catalytic polymerization using a radical polymerization initiator, ionization Radiation polymerization, redox polymerization, and the like can be appropriately employed.

The salt of the organic quaternary phosphonium compound (B) serving as a vulcanization accelerator and the nitrogen-containing heterocyclic compound is an organic quaternary phosphonium compound represented by the general formula R ¹ R ² R ³ R ⁴ P ^+. Including ions. Where R ¹ , R ² , R ³ ,
R ⁴ may be the same or different, and include an alkyl group such as a methyl group, an ethyl group, a butyl group, an ethylhexyl group and a dodecyl group; a cycloalkyl group such as a cyclohexyl group; an aralkyl group such as a benzyl group and a methylbenzyl group; A phenyl group, a naphthyl group, a hydrocarbon group having 1 to 20 carbon atoms such as a substituted or unsubstituted aryl group such as a butylphenyl group, a trifluoromethyl group, a linear chain having 1 to 20 carbon atoms such as a trifluoroethyl group, or Examples thereof include a halogenated hydrocarbon group having a branched structure.

Examples of the nitrogen-containing heterocyclic compound include pyrrolines, morpholines, pyrrolidines, pyrroles, pyrazoles, pyrazolines, imidazoles, imidazolines, benzotriazoles, benzimidazoles, indolines, and indoles. , Isoindoles,
Purines, carbazoles and the like can be mentioned. These nitrogen-containing heterocyclic compounds include a hydrocarbon group, a halogenated hydrocarbon group,
It may have a halogen atom, a hydroxyl group, or another substituent. Preferred nitrogen-containing heterocyclic compounds are imidazoles, benzimidazoles, benzotriazoles, imidazoles, and carbazoles which may have a substituent as described above. Preferred examples of the salt of the organic quaternary phosphonium compound and the nitrogen-containing heterocyclic compound include the following.

[0013] Tetrabutylphosphonium benzotriazolate, tetraoctylphosphonium benzotriazolate, methyltrioctylphosphonium benzotriazolate, butyltrioctylphosphonium benzotriazolate, phenyltributylphosphonium benzotriazolate, benzyltributylphosphonium benzotriazolate Azolate, benzyltricyclohexylphosphonium benzotriazolate, benzyltrioctylphosphonium benzotriazolate, butyltriphenylphosphonium benzotriazolate, octyltriphenylphosphonium benzotriazolate, benzyltriphenylphosphonium benzotriazolate, tetraphenyl Phosphonium benzotriazolate, 2,2,2-trifluoroethyl -Butyl phosphonium benzotriazolate, 2,2,3,3-tetrafluoropropyl trioctyl phosphonium benzotriazolate like benzotriazolate of. Benzimidazolates such as tetrabutylphosphonium benzimidazolate. Imidazolates such as tetrabutylphosphonium imidazolate; Carbazolates such as tetrabutylphosphonium carbazolate.

The above component (B) may be used alone or in combination of two or more. Component (B) is used in an amount of 0.1 to 10 parts by weight, particularly 0.1 to 10 parts by weight, per 100 parts by weight of the elastic copolymer.
-5 parts by weight is preferred. If the amount is less than 0.1 part by weight, it is difficult to obtain a sufficient vulcanization density and vulcanization properties, and if the amount exceeds 10 parts by weight, a scorch phenomenon or the like is caused, which adversely affects the molding process.
In addition, chemical resistance and the like are apt to decrease.

As the organic polyhydroxy compound of the component (C) acting as a vulcanizing agent, an aromatic polyhydroxy compound having two or more phenolic hydroxy groups is preferred because of its high vulcanizing activity. In some cases, a compound having an alcoholic hydroxy group can also be used. Particularly preferred organic polyhydroxy compounds are aromatic dihydroxy compounds having two phenolic hydroxy groups. The following are preferred examples of specific organic polyhydroxy compounds.

2,2-bis (4-hydroxyphenyl)
Propane, 2,2-bis (4-hydroxyphenyl) perfluoropropane [bisphenol AF], 1,3
5-trihydroxybenzene, 1,7-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-
Dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, catechol, 4,4′-dihydroxystilbene, 2,6-dihydroxyanthracene, hydroquinone, 2,2-bis (4-hydroxyphenyl) butane,
2,2-bis (4-hydroxyphenyl) tetrafluorodichloropropane, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylketone, tris (4-hydroxyphenyl) methane,
2,3,3,4,4-hexafluoropentane-1,5
-Diols, polyethylene glycols, ethylene glycol and the like.

As a derivative of the organic polyhydroxy compound of the component (C) acting as a vulcanizing agent, when the organic polyhydroxy compound is represented by D (OH) _n , D (OH)
Examples thereof include alcoholates, phenolates, and organic quaternary phosphonium salts represented by _nm (OM _{1 / p} ) _m . Here, n is the number of hydroxy groups in the organic polyhydroxy compound, M is an alkali metal such as Na or K, an alkaline earth metal such as Ca, or an organic quaternary phosphonium ion, p is an alkali metal, The valence of the alkaline earth metal or organic quaternary phosphonium ion, m is a positive integer of n or less.

As the component (C), one or more selected from organic polyhydroxy compounds and derivatives thereof can be used. The use amount of the component (C) (the total use amount in the case of using two or more kinds) is preferably 0.1 to 10 parts by weight, particularly preferably 0.5 to 5 parts by weight, per 100 parts by weight of the elastic copolymer. If the amount is too small, it is difficult to obtain a sufficient crosslink density, and if it is too large, the effect does not change.

As the metal oxide or hydroxide of the component (D) acting as an acid acceptor, oxides or hydroxides of divalent metals such as magnesium, calcium, lead and zinc are preferred. In addition, lithium hydroxide and the like can be used. Two or more types of component (D) may be used in combination. Component (D) is used in an amount of 1 to 50 parts by weight per 100 parts by weight of the elastic copolymer (particularly 2 parts).
-30 parts by weight are preferred.

The composition of the present invention may contain carbon black, fine silica,
Reinforcing agents such as clay and talc, other fillers, pigments,
Antioxidants, stabilizers, processing aids, internal mold release agents, and the like may be added and blended. In producing the composition of the present invention, it is desirable that the components (A), (B), (C), (D) and, if necessary, other additives are sufficiently mixed.

The mixing is carried out by using a kneading roll, a kneader, a Banbury mixer, an extruder, etc., which are conventionally ordinarily used. The working conditions at the time of mixing are not particularly limited, but the kneaded material is usually kneaded at about 30 to 130 ° C. for about 1 to 60 minutes at a temperature at which vulcanization hardly occurs, so that the additive compound can be dispersed in the elastic copolymer. Further, these additive compounds can be appropriately dissolved and dispersed in a solvent and mixed as a suspension solution.

Further, so-called wet mixing in which the mixing is performed in the medium from the beginning can also be performed. In this case, a solution or dispersion liquid composition can be obtained by using a mixer such as a roll, a ball mill, and a homogenizer. It is desirable that the operating conditions at the time of mixing be determined by selecting optimal conditions according to the types and purposes of the raw materials and the compounding agents used.

The composition of the present invention can be formed into a sheet, a pipe, a rod, a tube, an angle by continuous molding methods such as extrusion molding, transfer molding, roll coating, brushing and impregnation in addition to mold molding and injection molding. , Channel, tabi,
It can be formed into a molded product such as a coated plate. In addition, it can be formed into a deformed product or a specially formed product such as a sponge-like rubber by any of various other forming methods. The composition thus formed is vulcanized by the following vulcanizing means to obtain a vulcanized rubber product.

In the present invention, the vulcanizing operation may employ an operation conventionally used conventionally. For example, an operation of heating while applying pressure in a molding die may be employed, or an operation of heating in a heating furnace or the like after molding by extrusion molding or injection molding may be employed. The vulcanization temperature is usually 100
To 400 ° C., preferably about 150 to 200 ° C., and the vulcanization time ranges from about 30 seconds to several hours. The obtained vulcanized product may be subjected to secondary vulcanization. Physical properties may be improved by secondary vulcanization. The secondary vulcanization conditions are not particularly limited, and are appropriately selected depending on the shape and size of the molded product.
At 150-250 ° C, preferably 180-230 ° C, 2
It is about 25 hours.

[0025]

TFE with a small content of polymerized units based on VdF, TFE
The use of a specific organic quaternary phosphonium compound salt as a vulcanization accelerator in a -P-VdF-based elastic copolymer facilitates vulcanization of a polyol. Further, the obtained vulcanized product has a small amount of polymerized units based on VdF, and thus has excellent heat resistance and oil resistance.

[0026]

EXAMPLES Examples 1 to 7 are Examples and Examples 8 to 11 are Comparative Examples. Materials mixed with the compositions (units: parts by weight) shown in Tables 1 and 2 were uniformly mixed with two rolls to obtain a crosslinkable elastic copolymer composition. The vulcanization characteristics of this composition were measured using an oscillating disc rheometer (manufactured by Toyo Seiki) at 170 ° C. for 24 minutes at a minimum torque (M _L ), a maximum torque (M _H ) and a maximum torque of 90 ° C. The time until the% torque value was reached (t _c (90)) was measured. The composition was press-vulcanized at 170 ° C. for 20 minutes, and then heat-treated in an oven at 230 ° C. for 24 hours for secondary vulcanization.

The obtained vulcanized product was measured for normal physical properties, heat resistance (70 hours at 230 ° C.), and oil resistance (70 hours at 175 ° C.) in accordance with JIS-K6301. For the measurement of oil resistance, an SH class engine oil (Castle Motor Oil Clean SH manufactured by Toyota Motor Corporation) was used. The results are shown in Tables 3 and 4. “*” In the table indicates that a vulcanized sheet was not obtained.

Table 5 shows the abbreviations of Tables 1 and 2. The respective elastic copolymers used were produced by emulsion polymerization. The content ratio (mol%) of the polymerized units based on the respective monomers and Mooney viscosity ML _{1 + 10} (121 ° C.) are also shown in Table 5.
Shown in The composition of the polymerized unit based on each monomer of the component (A) was determined by ¹⁹ F-NMR and ¹ H-NMR. Further, unsaturated bonds of the elastic copolymer 5, the wave number 3120cm ^-1 in the infrared analysis, the presence than the absorption of 1722 cm ^-1 were observed.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

[0033]

[Table 5]

[0034]

The polymerized unit content based on VdF is small.
The composition containing the TFE-P-VdF elastic copolymer exhibits good polyol vulcanizability and gives a vulcanizate excellent in heat resistance and oil resistance. Furthermore, the vulcanized product has various excellent vulcanized physical properties, such as radiators of automobiles, O-rings around engines, gaskets, sealing materials, diaphragms, tubes, hoses, and similar parts such as food plants and chemical plants. It is very useful for a wide range of applications such as

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Claims (2)

[Claims] (A) 35-65 mol% of a polymerization unit based on tetrafluoroethylene, 20-50 mol% of a polymerization unit based on propylene, and 0.5-15 mol% of a polymerization unit based on vinylidene fluoride. (B) a salt of a nitrogen-containing heterocyclic compound and an organic quaternary phosphonium compound, (C) at least one selected from organic polyhydroxy compounds and derivatives thereof, and (D) metal oxidation. A cross-linkable elastic copolymer composition comprising at least one selected from a product and a metal hydroxide. 2. The crosslinkable elastic copolymer composition according to claim 1, wherein the nitrogen-containing heterocyclic compound is an imidazole, benzimidazole, benzotriazole or carbazole which may have a substituent. object.