JP3166053B2 - Method for producing thermoplastic elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic elastomer composition, and more particularly, to a peroxide crosslinked olefin copolymer rubber, a peroxide decomposable olefin plastic, an organic peroxide and, if necessary, an organic peroxide. Automotive interior / exterior parts, civil engineering and construction materials, industrial machinery parts, medical equipment, housing, OA parts, and miscellaneous products obtained by dynamically heat-treating and partially cross-linking a composition comprising a mineral oil-based softener and a crosslinking aid. The present invention relates to a method for producing a thermoplastic elastomer composition having excellent thin film moldability which can be extruded or injection-molded.

[0002]

2. Description of the Related Art Injection molding of ordinary rubber requires a special molding machine because a vulcanization step is required after compounding and kneading an additive with the rubber, molding in a mold, and a cycle time. However, there is a problem that the process is long and the process is complicated, and there is a similar problem in the extrusion molding, which is an obstacle to mass production of rubber products. Therefore, a thermoplastic elastomer composition which can be molded without vulcanization and has rubber-like performance has been desired.

A composition comprising a crosslinking agent such as a peroxide-crosslinkable olefin copolymer rubber, a peroxide-decomposable olefin-based plastic, or an organic peroxide is thermally treated in a molten state to partially crosslink with an olefin-based resin. The composition comprising the obtained rubber is already known as an olefin-based thermoplastic elastomer composition.

However, the thermoplastic elastomer composition is prepared by introducing an organic peroxide-decomposable olefin-based plastic and an organic peroxide-crosslinked olefin-based copolymer rubber into a continuous or batch kneader almost simultaneously. It is manufactured by heat treatment in the presence of oxide, and although it has excellent performance as a thermoplastic elastomer, its flowability is remarkably inferior to general-purpose plastic, and it is remarkable when it is extruded or injection molded There is a drawback that a product having a good appearance cannot be obtained due to a flow mark or the like.

In order to improve the fluidity of a thermoplastic elastomer composition and the shaping property of a thin film at the time of sheet molding, (a)
There are methods such as increasing the melt flow ratio (MFR) of the olefin-based plastic used, (b) decreasing the degree of crosslinking of the rubber portion in the thermoplastic elastomer composition, and the like. There is a problem that the strength of the olefin-based plastic decreases due to the decrease in the molecular weight of the olefin-based plastic, and the adhesive strength between the olefin-based plastic and the rubber decreases, so that the strength of the thermoplastic elastomer composition decreases. In the method (2), there is a problem that the strength of the thermoplastic elastomer composition is reduced when the degree of crosslinking of the rubber portion is reduced.

[0006] In order to improve the fluidity of the thermoplastic elastomer compositions without substantially impairing the heat resistance, tensile properties, flexibility and rebound resilience, a mineral oil softener is added to these compositions. Thereafter, a heat treatment in the presence of an organic peroxide may be performed dynamically, for example, as described in JP-B-56-15-15.
It is publicly known as described in Japanese Patent No. 741.

[0007]

SUMMARY OF THE INVENTION Incidentally, the present inventors, when producing a thermoplastic elastomer composition,
As a result of studying peroxide-decomposable olefin-based plastics, a peroxide-decomposable olefin-based plastic was decomposed in the presence of organic peroxides or under heat and shear, and then immediately decomposed. A thermoplastic elastomer composition obtained by adding a peroxide-crosslinked olefin copolymer rubber to a plastic and subjecting it to a crosslinking reaction in the presence of an organic peroxide is a peroxide-decomposed type in which the MFR is previously decomposed to increase the MFR to the same extent. It has been found that the tensile strength is improved as compared with a thermoplastic elastomer composition obtained by simultaneously adding an olefin plastic and a peroxide crosslinked olefin copolymer rubber and crosslinking in the presence of an organic peroxide. The invention of claim 1 has been completed.

Further, the present inventors have studied the timing of adding the mineral oil-based softening agent when producing the thermoplastic elastomer composition. As a result, the mineral oil-based softening agent was found to be a peroxide-crosslinked olefin copolymer rubber and In the process of dissolving in a resin made of an oxide-decomposable olefin-based plastic, a large viscosity unevenness occurs in the resin (the part where the mineral oil-based softener is dissolved has a low viscosity, and the others have a high viscosity), and the mineral oil-based softener is dissolved in the resin When a crosslinking reaction occurs in the process,
The high-viscosity portion is not kneaded (the high-viscosity portion is hard to be kneaded) and cross-linking is performed, which causes the generation of coarse particles of the cross-linked rubber. The coarse particles of the cross-linked rubber are processed into a thermoplastic elastomer sheet or the like. In this case, it became a fisheye, which was found to have an adverse effect on the appearance, physical properties and secondary workability of the product, and the invention of claim 2 of the present application was completed.

The present inventors have prepared a peroxide-decomposable olefin plastic in the presence of an organic peroxide.
Alternatively, when a degradation treatment is performed to decompose under heat and shear force, a large number of radicals are present in the peroxide-decomposed olefin-based plastic, and a peroxide-crosslinked olefin-based copolymer rubber is added to the olefin-based plastic. When the crosslinking reaction is performed in the presence of an organic peroxide, the adhesion at the interface between the peroxide-decomposable olefin-based plastic and the peroxide-crosslinked olefin-based copolymer rubber is improved, thereby improving the tensile strength. It is estimated to be.

Further, it has been found that the thermoplastic elastomer composition thus obtained has an increased MFR of the whole composition and not only improves the fluidity but also the tensile strength.

[0011]

Means for Solving the Problems The first invention of the present application is:
A mixture of (a) 50 to 93 parts by weight of a peroxide cross-linked olefin copolymer rubber and (b) 7 to 50 parts by weight of a peroxide decomposable olefin plastic (c)
In producing a thermoplastic elastomer composition which is subjected to dynamic heat treatment in the presence of an organic peroxide and partially crosslinked, (a) and (c) are immediately added after (b) is subjected to a degeneration treatment in advance. And a dynamic heat treatment, wherein the second invention comprises (a) 50 to 93 parts by weight of a peroxide crosslinked olefin copolymer rubber, (B)
Peroxide-decomposable olefin plastics 7-5
0 parts by weight of the mixture is subjected to dynamic heat treatment in the presence of (c) an organic peroxide to produce a partially crosslinked thermoplastic elastomer composition. a) and (c) are added, and a dynamic heat treatment is performed. After the partial crosslinking reaction is completed, (d) a mineral oil softener 5
A method for producing a thermoplastic elastomer composition, characterized by adding about 300 parts by weight.

The (a) peroxide-crosslinked olefin copolymer rubber used in the present invention is an amorphous random elastic copolymer containing olefin as a main component, which is mixed with an organic peroxide and heated. A rubber that can be crosslinked by kneading underneath to reduce or lose its fluidity, for example, a rubber such as an ethylene-propylene copolymer rubber, an ethylene-propylene-nonconjugated diene rubber, or an ethylene-butadiene copolymer rubber. Among them, ethylene-propylene copolymer rubber and ethylene-propylene-non-conjugated diene rubber are preferable, and as the ethylene-propylene-non-conjugated diene copolymer rubber, a diene monomer having 5 to 20 carbon atoms is preferable. Conjugated dienes such as 1,4-pentadiene, 1,4- and 1,5-hexadiene, 2, Cyclic diene, such as 1,4-cyclohexadiene, cyclooctadiene, dicyclopentadiene, alkenylnorbornene, such as 5-dimethyl-1,5-hexadiene and 1,4-octadiene; Norbornene, 2-methallyl- and 2-isopropenyl-5-
Examples thereof include those using norbornene and the like, and among them, ethylene-propylene-ethylidene norbornene copolymer rubber is particularly preferable because a composition having excellent heat resistance, tensile properties, and rebound resilience can be obtained.

The (b) peroxide-decomposable olefin-based plastic used in the present invention contains a crystalline portion which is degraded in the presence of an organic peroxide or under heat and shear to increase the fluidity of the resin. Olefin-based plastics, including, for example, crystalline high molecular weight solid products obtained from the polymerization of one or more monoolefins, with preferred examples of olefins being propylene, 1-butene, 1- Pentene, 1-hexene, 2
-Methyl-1-propene, 3-methyl-1-pentene,
4-methyl-1-pentene and 5-methyl-1-hexene homopolymers and copolymers, and mixtures thereof, and particularly preferably polypropylene resins.

The polypropylene resin is isotactic polypropylene or a random or block copolymer of propylene with an α-olefin such as ethylene, butene-1, hexene-1 or the like, wherein the crystal part is polypropylene. It is.

In the present invention, it is necessary to adjust the melt flow rate of the peroxide-decomposable olefin-based plastic to 50 to 10,000 g / 10 minutes by a degeneration treatment. The degradation is performed in the presence of an organic peroxide or by heat and shear.

In the case of decomposition by an organic peroxide, it may be carried out by melt-kneading at 170 to 250 ° C. for 0.5 to 5 minutes in the presence of the organic peroxide. The amount of the organic peroxide to be used is 2 parts by weight or less based on 100 parts by weight of the peroxide-decomposable olefin-based plastic, and can be appropriately changed depending on the desired melt flow rate.

In the present invention, the decomposition of the peroxide-decomposable olefin-based plastic under heat and shear force is defined as:
29 peroxide-decomposable olefin plastics
A time sufficient to decompose in the range 0-480 ° C, preferably 320-450 ° C, typically 1-10 minutes,
It is preferably kneaded for 2 to 6 minutes to decompose.

In the present invention, the peroxide-decomposable olefin-based plastic contributes to improving the fluidity and heat resistance of the composition, and the amount of the peroxide-decomposable olefin-based plastic relative to 100 parts by weight of the total composition. Is in the range of 7 to 50 parts by weight, preferably 10 to 40 parts by weight, and if it exceeds 50 parts by weight, the flexibility and rebound resilience of the composition are impaired and the product becomes sinkage. If the amount of the oxide-decomposable olefin-based plastic is less than 7 parts by weight, the heat resistance and fluidity of the composition will be impaired, and the object of the present invention will not be achieved.

The mineral oil-based softener (d) used in the present invention usually weakens the intermolecular force of the rubber when the rubber is roll-processed, thereby facilitating the process, and at the same time, such as carbon black and white carbon. It is blended to assist dispersion and to improve the fluidity and flexibility of the thermoplastic elastomer.A paraffinic, naphthenic, aromatic or other softener can be used, and paraffinic and tephthenic are particularly preferred. .

In the present invention, the blending amount of the mineral oil-based softener is
Total amount of peroxide-crosslinked olefin copolymer rubber and peroxide-decomposed olefin plastic 1
5 to 300 parts by weight, preferably 10 to 2 parts by weight, per 100 parts by weight
When the amount is less than 5 parts by weight, there is no sufficient effect of improving the fluidity of the thermoplastic elastomer composition, and when it exceeds 300 parts by weight, the heat resistance of the composition is increased. And the softening agent exudes to impair the appearance.

The mineral oil-based softener may be present before the dynamic heat treatment, but is preferably added after melt-kneading after the dynamic heat treatment to complete the crosslinking reaction.

In the present invention, the organic peroxide used for crosslinking the peroxide-crosslinked olefin copolymer rubber or for decomposing the peroxide-decomposable olefin plastic includes, for example, dicumyl peroxide,
t-butyl peroxide, 2,5-dimethyl-2,5-
Di- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-
3,1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t-butylperoxy)
-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate,
Benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t
-Butylperoxybenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, t-butylcumyl peroxide and the like.
-Dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,1,3-bis (t-butylperoxyisopropyl) benzene , 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and n-butyl-4,4-bis (t-butylperoxy) valerate are preferred, and in particular, 2,5-dimethyl-2 , 5-di (t-butylperoxy) hexyne-
3, is most preferred.

When the peroxide-crosslinked olefin copolymer rubber undergoes a crosslinking reaction, it is preferably 0.05 to 2 parts by weight, particularly preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the total amount of the resin.
It should be selected so as to be in the range of 1 to 1 part by weight, and if the compounding amount is less than 0.05 part by weight, the degree of crosslinking of the peroxide-crosslinked olefin copolymer rubber is too small, and as a result, Insufficient rubber properties such as heat resistance, tensile properties, elastic recovery, and rebound resilience. On the other hand, if it exceeds 2 parts by weight, the degree of crosslinking of the peroxide-crosslinked olefin copolymer rubber increases, resulting in flow of the entire composition. Is reduced.

In the present invention, a crosslinking aid can be used together with these crosslinking agents, if necessary, at the time of dynamic heat treatment. As the crosslinking aid used in the present invention, a peroxide crosslinking type, polyfunctional Functional (meth) acrylate monomers, polyfunctional vinyls and metal salts of α, β-unsaturated carboxylic acids, such as sulfur, p-quinone oxime, p, p′-dibenzoylquinone dioxime, N-methyl- N, 4-dinitrosoaniline, nitrobenzene,
Organic peroxide crosslinking aids such as vinyl butyrate, vinyl stearate, zinc acrylate, zinc methacrylate, diphenylguanidine, trimethylolpropane, N, N'-m-phenylenedimaleimide, divinylbenzene (DVB), ethylene Glycol dimethacrylate, pentaerythritol triacrylate,
1,3-butylene glycol dimethacrylate, trimethylolpropane trimethacrylate (TMPT), triallyl cyanurate, triallyl isocyanurate,
Diallyl phthalate, diallyl terephthalate, polyethylene glycol dimethacrylate, 1,2-polybutadiene, maleic anhydride, neopentyl glycol diacrylate, and glycidyl methacrylate. Particularly, in the present invention, when trimethylolpropane trimethacrylate is used, it is easy to handle, and the phase to the peroxide-crosslinked olefin copolymer rubber and the peroxide-decomposed olefin plastic, which are the main components of the object to be treated, is improved. It has good solubility, has a solubilizing effect of organic peroxide, and acts as a peroxide dispersing agent, so that a cross-linking effect by heat treatment is uniform, and a composition with good balance between fluidity and physical properties can be obtained. Most preferred There.

The amount of the crosslinking aid is preferably in the range of 0.05 to 2% by weight, particularly 0.1 to 1% by weight, and more preferably in the range of 0.1 to 1% by weight, based on 100 parts by weight of the resin component. When the amount of peroxide is large, the crosslinking reaction proceeds, resulting in poor fluidity of the composition.On the other hand, when the amount of organic peroxide is small, as an unreacted monomer,
Excessive compounding should be avoided because it is present in the composition and may cause changes in physical properties due to heat history during processing and molding the composition.

In the present invention, tertiary amines such as triethylamine and tributylamine, and aluminum, cobalt, vanadium, copper, calcium, zirconium, manganese, magnesium, lead, mercury and the like are used to promote the decomposition of organic peroxides. Decomposition accelerators such as organic metal carboxylate such as naphthenate and octanoate can also be used.

In the production method of the present invention, the peroxide-decomposable olefin-based plastic of each of the above-mentioned components is decomposed in advance in the presence of an organic peroxide or under heat and shear, and is converted into a resin in a molten state. Add the remaining components and dynamically heat-treat to perform a partial cross-linking reaction, or add a component obtained by removing the mineral oil-based softener from the remaining components,
The partial cross-linking reaction is terminated, and thereafter, a mineral oil-based softening agent is added and kneaded and dissolved.

As the kneading apparatus, conventionally known ones such as an open-type mixol, a non-open-type Banbury mixer, an extruder, a kneader, and a continuous mixer can be used. Among these, it is preferable to use a non-opening type device, and it is preferable to knead under an inert gas atmosphere such as nitrogen or carbon dioxide gas when performing a crosslinking reaction.

The kneading is carried out at a temperature at which the half-life of the organic peroxide used is less than 1 minute, usually 150 to 280 ° C., preferably 170 to 240 ° C., for 1 to 20 minutes, preferably 3 to 10 minutes. I just need.

The composition obtained by the production method of the present invention can be molded by an apparatus used for ordinary thermoplastics, is suitable for extrusion molding, calender molding, and injection molding. Since the system copolymer rubber component is partially crosslinked, it has excellent rubber properties such as heat resistance, weather resistance, tensile properties, flexibility and rebound resilience, and has good flowability. Are better.

The thermoplastic elastomer composition produced by the method of the present invention contains fillers such as calcium carbonate, calcium silicate, clay, kaolin, talc, silica and diatom as long as the fluidity and rubber properties are not impaired. soil,
Mica powder, asbestos, alumina, barium sulfate, aluminum sulfate, calcium sulfate, basic magnesium carbonate, molybdenum disulfide, graphite, glass fiber, glass sphere, shirasu balloon, carbon fiber, etc. or coloring agent, for example, carbon black, titanium oxide , Zinc flower,
Bengal, ultramarine, navy blue, azo pigment, nitroso pigment, lake pigment, phthalocyanine pigment, etc.
Furthermore, if necessary, it is usually used in resins or rubbers such as antioxidants, ultraviolet absorbers, stabilizers such as metal deterioration inhibitors, lubricants, antistatic agents, electric property improvers, flame retardants, and processability improvers. The additives to be blended can be blended.

The thermoplastic elastomer composition produced by the method of the present invention may be used for interior and exterior parts of automobiles such as body panels, bumper parts, side shields and steering wheels, materials for civil engineering and construction, and industrial machine parts such as gaskets. OA parts such as medical equipment, housing, electric wire coating, connector, cap plug, leisure goods,
It can be used for miscellaneous goods such as garden hoses, belts and footwear.

[0033]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples unless it departs from the gist thereof.

In Examples and Comparative Examples of the present invention,
The following raw materials were used. 1. Peroxide-crosslinked olefin copolymer rubber EPDM: ethylene-propylene-ethylidene norbornene copolymer rubber [Mooney viscosity ML 1 + 4 (100
° C) = 88, iodine value 15.0, propylene content 28
% By weight] Peroxide-decomposable olefin plastic BPP-1: Propylene-ethylene block copolymer (BPP) [density 0.90 g / cm ³ , melt flow rate (MFR, 230 ° C, 2.16 kg load) 40 g /
10 minutes, ethylene content 7% by weight] BPP-2: BPP-1 is treated with an organic peroxide to obtain M
BPP with FR of 70 g / 10 minutes BPP-1: BPP-1 was treated with an organic peroxide to obtain M
2. BPP with FR of 200 g / 10 min. Mineral oil softener Oil: paraffin softener [15.degree.
0 g / cm ³ viscosity index 110] 4. 4. Organic peroxide POX: 2,5-dimethyl-2,5- (t-butylperoxy) hexyne-3, Crosslinking aid TMPT: trimethylolpropane trimethacrylate, (Example 1) BPP-1: 25 parts by weight in a first hopper of a co-rotating twin-screw kneader TEX54 (manufactured by Nippon Steel Works)
0.05 parts by weight of POX were charged and the cylinder temperature was 28
Decomposed in the decomposition zone at 0 ° C. The MFR of the obtained BPP was 210.

To the BPP decomposed in the decomposition zone, 75 parts by weight of EPDM, 0.12 parts by weight of POX, T
0.12 parts by weight of MPT was charged and subjected to dynamic heat treatment in a heat treatment zone at a cylinder temperature of 200 ° C. under a nitrogen atmosphere to terminate the cross-linking reaction.
A part by weight was injected, and oil was kneaded in a zone at a cylinder temperature of 200 ° C. to produce a thermoplastic elastomer composition.

The thermoplastic elastomer composition was formed into a sheet by a T-die using an extruder, and the thin film formed was evaluated. The results are shown in Table 1 together with the tensile strength.

Example 2 A thermoplastic elastomer composition was produced in the same manner as in Example 1, except that the amount of POX added in the decomposition zone was 0.2 parts by weight.

The evaluation results of the obtained composition are shown in Table 1.

(Example 3) Example 2 was repeated except that 25 parts by weight of BPP-1 was charged into the first hopper of the kneader without adding POX to the decomposition zone, and decomposed in the decomposition zone at a cylinder temperature of 400 ° C. In the same manner as in Example 1, a thermoplastic elastomer composition was produced.

The evaluation results of the obtained composition are shown in Table 1.

Comparative Example 1 BPP-1: 25 parts by weight, E
PDM: 75 parts by weight, POX: 0.12 parts by weight, TMP
T: A material composition consisting of 0.12 parts by weight was put into a hopper of a kneading machine, and a cylinder temperature of 200 ° C. under a nitrogen atmosphere.
In the heat treatment zone, a dynamic heat treatment is performed to terminate the crosslinking reaction, 37 parts by weight of Oil are injected from a nozzle provided at the position, and oil is kneaded in a cylinder temperature zone of 200 ° C.
A thermoplastic elastomer composition was produced.

The evaluation results of the obtained composition are shown in Table 1.

Comparative Example 2 BPP-2 instead of BPP-1
A thermoplastic elastomer composition was produced in the same manner as in Comparative Example 1 except for using.

Table 1 shows the evaluation results of the obtained compositions.

Comparative Example 3 BPP-3 instead of BPP-1
A thermoplastic elastomer composition was produced in the same manner as in Comparative Example 1 except for using.

The evaluation results of the obtained composition are shown in Table 1.

[0047]

[Table 1] From Table 1, BPP-1 is decomposed with organic peroxide,
The compositions of Examples 1 to 3 using those obtained by adding a residual component to a material still in a molten state, performing a dynamic heat treatment, and performing a partial crosslinking reaction, are undecomposed or previously decomposed BPP. Is excellent in the tensile strength and the moldability as compared with the compositions of Comparative Examples 1 to 3 using the same. Particularly, although the MFR is substantially the same between Example 1 and Comparative Example 3, there is a large difference in the tensile strength. You can see that there is.

[0048]

As described above, according to the production method of the present invention, the fluidity and the thin film moldability during sheet molding are improved, and a large amount of radicals are present in the peroxide-decomposable olefin plastic. , A cross-linking reaction with the olefin-based copolymer rubber was performed, so that the adhesiveness at the interface between the two was improved, and the thermoplastic elastomer composition obtained by the production method had significantly improved tensile strength.

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Claims (2)

(57) [Claims] 1. A mixture of (a) 50 to 93 parts by weight of a peroxide-crosslinked olefin-based copolymer rubber and (b) 7 to 50 parts by weight of a peroxide-decomposable olefin-based plastic, and (c) the presence of an organic peroxide. In order to produce a thermoplastic elastomer composition which is subjected to dynamic heat treatment below and partially crosslinked, dynamic heat treatment is performed by adding (a) and (c) immediately after (b) is subjected to a degradation treatment in advance. A method for producing a thermoplastic elastomer composition, comprising: 2. A mixture of (a) 50 to 93 parts by weight of a peroxide-crosslinked olefin-based copolymer rubber and (b) 7 to 50 parts by weight of a peroxide-decomposable olefin-based plastic, and (c) the presence of an organic peroxide. In order to produce a thermoplastic elastomer composition which is subjected to a dynamic heat treatment below and partially crosslinked, (a) and (c) are added immediately after the degradation treatment of (b) in advance, followed by a dynamic heat treatment. A method for producing a thermoplastic elastomer composition, which comprises adding (d) 5 to 300 parts by weight of a mineral oil-based softener after the completion of the partial crosslinking reaction.