JPS5856575B2 - Method for producing thermoplastic elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a thermoplastic elastomer composition.

More specifically, the present invention relates to a method for producing a partially crosslinked olefinic thermoplastic elastomer composition, which is particularly suitable for extrusion molding or injection molding of large, thick-walled products.

When injection molding regular rubber, additives are added to the rubber,
Since it is necessary to knead it, supply it into a mold, and then vulcanize it, there are problems in that a special molding machine is required, the cycle time is long, and the process is complicated.

A similar problem exists in extrusion molding, which has been a bottleneck in the mass production of rubber products.

Therefore, alternatives to rubber are being considered using materials that can be molded without vulcanization and have properties similar to rubber.

Among materials with such performance, soft plastics such as soft vinyl chloride resin, ethylene-vinyl acetate copolymer, and low-density polyethylene have the advantages of good moldability and high flexibility. On the other hand, its uses are severely limited due to drawbacks such as poor heat resistance and rebound resilience.

Attempts have been made to improve heat resistance and mechanical strength by mixing soft plastics with plastics with high melting points, such as high-density polyethylene and polypropylene, but this results in loss of flexibility and the need for thick products. When molding, whiskers occur and a good product cannot be obtained.

Therefore, recently, so-called thermoplastic elastomers have begun to attract attention as having performance intermediate between vulcanized rubber and soft plastics.

Olefinic thermoplastic elastomers are also already known,
For example, a graft copolymer of polyethylene-butyl rubber,
Alternatively, several materials have been proposed that contain ethylene-propylene non-co-containing diene rubber as a main component.

As one type of olefin-based thermoplastic elastomer, a composition comprising a polyolefin plastic and partially crosslinked rubber is also known from JP-A-48-26838.

According to additional tests conducted by the present inventors, this composition has excellent performance as a thermoplastic elastomer, but its fluidity is significantly inferior to that of general-purpose plastics, and it is difficult to injection mold thick or large products. It has become clear that, in this case, noticeable flow marks occur and a product with good appearance cannot be obtained.

As a method for improving the fluidity of a composition consisting of a polyolefin plastic and partially crosslinked rubber, (
Possible methods include (a) using polyolefin plastics and/or raw material rubber with low molecular weight, (b) lowering the degree of crosslinking of rubber, and ()) increasing the blending ratio of polyolefin plastics, but method (10) The method (b) results in a decrease in the tensile properties of the composition. The method (b) results in a decrease in the heat resistance, tensile properties, and rebound resilience of the composition. The method ←→ results in a loss of flexibility of the composition and results in a thick product. In some cases, this resulted in disadvantages such as the tendency to form whiskers.

An object of the present invention is to provide a method for producing a thermoplastic elastomer composition having good heat resistance, tensile properties, weather resistance, flexibility, and rebound resilience.

Another object of the present invention is to provide a method for producing a thermoplastic elastomer composition that has good flow properties and can be easily formed into large, thick-walled products without whiskers or flow marks by extrusion or injection molding. There is a particular thing.

Still another object of the present invention is to improve the fluidity of the thermoplastic elastomer composition disclosed in JP-A-4826838 without substantially impairing the heat resistance, tensile properties, flexibility, and impact resilience. Therefore, it is an object of the present invention to provide a method for producing an improved composition in order to obtain a product with good appearance.

That is, the present invention provides (a) 90 to 40 parts by weight of peroxide crosslinked olefin copolymer rubber, and (b) 10 to 60 parts by weight of peroxide decomposition type olefin plastic (herein a) + (b) is 100 parts by weight. (c) a mixture of 5 to 100 parts by weight of peroxide non-crosslinked hydrocarbon rubber (excluding polyisobutylene and imbutylene-isoprene copolymer rubber); The present invention relates to a method for producing a partially crosslinked thermoplastic elastomer composition, characterized by dynamic heat treatment in the presence of a thermoplastic elastomer composition.

In the present invention, (a) peroxide crosslinked olefin copolymer rubber includes olefin as a main component, such as ethylene-propylene copolymer rubber, ethylene-propylene-non-copolymer rubber, and ethylene-butadiene copolymer rubber. An amorphous random elastic copolymer having
Rubber that is crosslinked by mixing with peroxide and kneading under heating, resulting in decreased fluidity or no longer flowing.

Among these, ethylene-propylene copolymer rubber,
Ethylene-propylene-non-component diene rubber (here, non-component diene refers to dicyclopentadiene, 4-hexadiene, cyclooctadiene, methylene norbornene, ethylythene norbornene, etc.) is preferable, especially ethylene Among the propylene-non-cocondensed diene copolymer rubbers, ethylene-propylene-ethyritene norbornene copolymer rubber is particularly preferred since it provides a composition with excellent heat resistance, tensile properties, and rebound properties.

Mooney viscosity ML of copolymer rubber, +4 (100°C)
The Mooney viscosity is preferably from 10 to 1201, particularly from 40 to 80; if the Mooney viscosity is less than 10, a composition with poor tensile properties will be obtained, while if it exceeds 120, the fluidity of the composition will be poor. Undesirable.

Further, the iodine value (degree of unsaturation) of the rubber is preferably 16 or less, and within this range, a partially crosslinked composition with well-balanced fluidity and rubbery properties can be obtained.

In the present invention, (b) peroxide-decomposable olefin-based plastic refers to an olefin-based plastic that is mixed with peroxide and kneaded under heat to thermally decompose, reduce the molecular weight, and increase the fluidity of the resin. Isotactic polypropylene and copolymers of propylene and small amounts of other α-olefins, such as propylene-ethylene copolymers, propylene-1-butene copolymers, propylene-1-hexene copolymers, propylene-4-
Examples include methyl-1-pentene copolymer.

The melt index (ASTM-D-1238-65T, 230°C) of the olefin plastic to be mixed is 0.1 to 50. Particularly preferred are those in the range of 5 to 20.

In the present invention, the olefin plastic has the role of improving the fluidity and heat resistance of the composition.

The amount of olefin plastic (b) based on 100 parts by weight of component (a) + component (b) in the composition is 10 parts by weight.
It should be in the range from 20 to 60 parts by weight, preferably from 20 to 50 parts by weight; more than 60 parts by weight will impair the flexibility and rebound properties of the composition and will result in the formation of baldness in the product.

On the other hand, if the amount of olefin plastic is less than 10 parts by weight, the heat resistance and fluidity of the composition will be impaired, making it unsuitable for the purpose of the present invention.

Next, (e) peroxide non-crosslinked hydrocarbon rubber material in the present invention is, for example, propylene-ethylene copolymer rubber containing 70 mol% or more of propylene, propylene-ethylene copolymer rubber, etc.
Refers to hydrocarbon-based rubber-like substances such as 1-butene copolymer rubber and atactic polypropylene that do not crosslink or lose fluidity even when mixed with peroxide and kneaded under heat.

In addition, in the present invention, crosslinking refers to a competitive reaction between a crosslinking reaction and a repellent decomposition reaction in which a polymer is thermally reacted with a peroxide, and as a result, the apparent molecular weight of the polymer increases. Decomposition refers to a phenomenon in which the apparent molecular weight of a polymer decreases as a result of many decomposition reactions.

The Mooney viscosity of the hydrocarbon rubbery substance (e) is 60
The following is preferable from the viewpoint of improving the fluidity of the composition.

The blending amount of the rubbery substance (e) is the above component (a) + (b)
) 5 to 100 parts by weight, preferably 5 to 40 parts by weight, particularly preferably 5 to 20 parts by weight, based on 100 parts by weight of the component.If the amount exceeds the above range, the heat resistance and tensile properties of the composition may deteriorate. The same disadvantages arise when the degree of crosslinking of the treated (aJ) rubber is too low.

A feature of the present invention is that (C) a peroxide non-crosslinked hydrocarbon rubber-like substance is blended into the composition consisting of the above <a.> peroxide crosslinked olefin copolymer rubber and (b) peroxide decomposed olefin plastic. By partially peroxide crosslinking, rubber-like properties such as heat resistance, tensile properties, flexibility, and rebound properties are substantially improved compared to a composition similarly produced without incorporating the above component (c). It is possible to obtain a composition with improved flowability without any loss in quality, and as a result, it is possible to mold large and thick products with excellent appearance and no whiskers.

In the present invention, examples of organic peroxides used for crosslinking or decomposing rubber and plastics include dicumyl peroxide, di-tert-butyl peroxide,
・5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane,
t-butylperoxy)hexyne-3,1,3-bis(
tert-butylperoxyisopropyl)benzene,
1,1-bis(tert-butylperoxy)-3,3
・5-trimethylcyclohexane, n-7” thyl-4・
4-bis(tert-butylperoxy)valerate,
pensoylperoxide, p-chlorobenzoylperoxide, 2,4-dichlorobenzoylperoxy)s,
tert-butyl peroxybenzoate, tert-
Butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tert
-butylcumyl peroxide and the like.

Among these, in terms of odor and scorch stability,
5-dimethyl-2,5-di(ter't-butylperoxy)hexane, 2,5-dimethyl-2,5-di(te
rt-7"tylperoxy)hexyne-3,1,3-bis(tert-7"tylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-
3,3,5-trimethylcyclohexane and n-butyl-4,4-bis(tert-butylperoxy)valerate are preferred, especially 1,3-bis(tert-7
"Tylperoxyisopropyl)benzene is most preferred.

The amount of organic peroxide to be blended should be selected so as to be preferably in the range of 0.05 to 1.0% by weight, particularly 0.1 to 0.5% by weight, based on the entire material to be treated.

If the blending amount is less than 0.05% by weight, the degree of crosslinking of the crosslinked rubber (a) will be too low, resulting in the composition not having sufficient rubber properties such as heat resistance, tensile properties, elastic recovery, and rebound resilience. On the other hand, if it exceeds 1.0% by weight (aJ), the degree of crosslinking of the peroxide crosslinked rubber increases, resulting in a decrease in the fluidity of the entire composition.

In the method for producing a composition of the present invention, in the partial crosslinking treatment with the organic peroxide, sulfur, p-quinonedioxime, p-p'-dibenzoylquinonedioxime,
Peroxy crosslinking coagents such as N-methyl-N.4-dinitronaniline, nitrobenzene, diphenylguanidine, trimethylolpropane-N-N'-m-phenylene dimaleimide, or divinylbenzene, triallyl cyanurate, ethylene glycol di methacrylate,
Polyfunctional methacrylate monomers such as diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, allyl methacrylate, and monofunctional vinyl monomers such as vinyl butyrad or vinyl stearate can be incorporated.

With such a compound, a uniform and mild crosslinking reaction can be expected.

In particular, in the present invention, when divinylbenzene is used, it is easy to handle, has good compatibility with olefin rubber and olefin plastic, which are the main components of the treated material, and has an organic peroxide solubilizing effect. ,
Since it acts as a peroxide dispersion aid, the crosslinking effect by heat treatment is homogeneous, and a composition with well-balanced fluidity and physical properties can be obtained, which is the most preferable.

In the present invention, the blending amount of such a crosslinking aid or polyfunctional to monofunctional vinyl monomer is in the range of 0.1 to 2% by weight, particularly 0.3 to 1% by weight, based on the entire object to be treated. is preferable, and when it is blended in an amount exceeding 2% by weight, when the blending amount of organic peroxide is large, the crosslinking reaction progresses, resulting in poor fluidity of the composition, while on the other hand, when the blending amount of organic peroxide is small, unreacted monomers Excessive blending should be avoided, since it is present in the composition and may cause changes in physical properties due to thermal history during processing and molding of the composition.

In the present invention, in order to promote the decomposition of organic peroxides, triethylamine, tributylamine, 2.4.
Tertiary amines such as 6-tris(dimethylamino)phenol, aluminum, cobalt, vanadium, copper, calcium, zirconium, manganese, magnesium, lead,
Decomposition accelerators such as naphthenates such as mercury and organometallic carboxylates such as octanoates can also be used.

The composition produced by the method of the present invention may contain fillers such as calcium carbonate, calcium silicate, clay, kaolin, talc, etc., to the extent that fluidity and rubbery properties are not impaired.
Silica, diatomaceous earth, mica powder, asbestos, alumina,
Barium sulfate, aluminum sulfate, calcium sulfate, basic magnesium carbonate, molybdenum disulfide, graphite, glass fiber, glass bulbs, shirasu balloons, carbon fiber, etc., or colorants such as carbon black, titanium oxide, zinc white, red iron, ultramarine , dark blue, azo pigment,
Nitroso pigments, lake pigments, phthalocyanine pigments, etc. can be blended.

The present invention also uses known heat stabilizers such as phenolic, sulfide, phenylalkane, phosphite or amine stabilizers, anti-aging agents, weather stabilizers, antistatic agents, lubricants such as metal soaps and waxes. etc.,
It can be blended to the extent used in olefin plastics or olefin copolymer rubbers.

In the manufacturing method of the present invention, the components described above are mixed and dynamically heat treated, that is, melted and kneaded.

As the kneading device, conventionally known devices such as an open mixigroll, a closed Banbury mixer 1 extruder, and a kneader 1 continuous mixer can be used.

Among these, it is preferable to use a closed type apparatus, and it is preferable to knead in an atmosphere of an inert gas such as nitrogen or carbon gas.

The kneading is carried out at a temperature such that the half-life of the organic peroxide used is less than 1 minute, usually 150 to 280°C, preferably 1 minute.
at 70 to 240°C for 20 minutes, preferably 3
You can do this for 10 minutes.

In the present invention, preferred methods for mixing and kneading each component include (1) daJ peroxide crosslinking olefin copolymer rubber, (b) peroxide decomposed olefin plastic, (CJ peroxide non-crosslinking hydrocarbon rubber) A lubricant is mixed in advance and, if necessary, a lubricant, and after uniformly kneading, an organic peroxide and, if necessary, a crosslinking aid, a decomposition accelerator, or a polyfunctional or monofunctional vinyl monomer are further blended, It is preferable to employ a method of kneading under the above-mentioned predetermined conditions.

Weather stabilizers, heat stabilizers, anti-aging agents, colorants, etc. may be added at any stage of the process.

When used, the thermoplastic elastomer composition obtained by the production method of the present invention may further contain a small amount of olefin rubber and/or olefin plastic, for example, up to 10% by weight based on the composition.

Even if such a polymer is contained, the fluidity of the composition
Physical properties remain essentially unchanged.

The composition obtained by the production method of the present invention can be molded using equipment commonly used for thermoplastics, and is suitable for extrusion molding, calendar molding, and especially injection molding.

The composition obtained by the production method of the present invention also has excellent rubber properties such as heat resistance, weather resistance, tensile properties, flexibility, and rebound resilience because component (a) is partially crosslinked.
It also has good fluidity, so when making large thick products,
A product with a good appearance without flow marks or whiskers can be obtained.

The thermoplastic elastomer produced by the method of the present invention can be used for body panels, bumper parts, sight shields, automobile parts such as steering wheels, footwear such as shoe soles and sandals, electric wire coverings, connectors, camping plugs, etc. Possible items include electrical parts, golf club grips, baseball bat grips, swimming fins, leisure goods such as underwater glasses, and miscellaneous goods such as gaskets, waterproof cloth, garden hoses, and belts.

The compositions produced by the method of the invention are particularly suitable for use in large, thick-walled products such as bumper parts.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples in any way unless it exceeds the gist thereof.

The moldability and basic physical properties of the compositions in Examples were evaluated by the following methods.

〔Test method〕

(1) Injection moldability (8. Molding conditions Injection molding was performed using the following equipment and conditions.

Molding machine 2-dynamelter (manufactured by Keine Seisakusho) Molding temperature: 2
00℃ Injection pressure crab - Next pressure 1300kg/cm Secondary pressure 700kg/So-called injection pressure crab Maximum molding speed 290 seconds/1 cycle Gate: Direct gate (land length 1゜rttra
, width 10mrn, thickness 3mm) Molded products: 3 types of square plates (length 300mrn, width 180mrn)
/111L1 Thickness 3.8.15□0 (B) Appearance judgment criteria for molded products (1) Flow mark rating: Judgment criteria 1: Significantly large number of flow marks 2: Significantly visible on the entire surface of the molded product 3: Full surface 4: Slightly visible only on the opposite side of the gate 5: No flow marks at all (2) Sink rating 2 criteria ○: No whiskers at all △: On the gate Appearing only on the opposite side ×: Appearing over the entire surface (3) Surface gloss Measured at an incident angle of 60° according to the method of ASTM-D-523.

Grade 2 criteria ○: Nigelos 25% or more △10-25% Nigelos × Less than 10% Nigelos (4) Extrusion moldability (A) Molding conditions Extrude the tube using the following equipment and conditions. Shaped.

Molding machine: 40mm diameter extruder (manufactured by Toshiba Machine) Molding temperature: 2
10°C Die: Straight die (Die/Core 12.5mm/1'0.0mm) Take-up speed: 10m/Standard (B) Appearance evaluation criteria for molded product The unevenness of the surface of the tube is evaluated on the following five scales.

Score 2 Judgment Criteria 5: Skin is extremely smooth and shiny 4: Skin is smooth but not shiny 3: Slightly rough skin 2: Severely rough skin with large wavy rough skin (5) By injection molding using the method of basic physical properties (1) A test piece was cut from the obtained square plate with a thickness of 3 um and measured by the following method.

Tensile properties: Measured by the method of JIS K-6301.

Spring hardness: JIS as described in JIS K-6301
Measured by A type method.

Permanent elongation: Measured by JIS-6301 method.

Heat-resistant temperature: Place the test piece in a constant temperature bath and set the temperature of the bath to 20℃.
/mat, and a diameter of 0.5 mm was heated under a load of 49 g.
The temperature was expressed as the temperature at which an 8-meter needle applied 0.1 mw to the sample.

Example 1 An ethylene-phlohylene-ethylidene norbornene copolymer rubber (hereinafter referred to as EPDM
1)) 70 weight tone L melt index (AST
M-D-1238-65T, 230°C) 13, density 0.
91? /crtt, Polyglopy☆☆Ren (hereafter PP
) 30 parts by weight and propylene content 71 mol%
, reduced specific viscosity (135°C, in decalin) 1.3 dll?
30 parts by weight of propylene-ethylene copolymer rubber (hereinafter abbreviated as PER) was kneaded in a Banbury mixer at 180°C for 5 minutes in a nitrogen atmosphere, passed through a roll, and pellets were produced using a sheet cutter.

Next, the pellets and 0.3 parts by weight of 1,3-bis(tert-butylperoxyisoglobil)benzene (hereinafter abbreviated as peroxide A) were dissolved and dispersed in 0.5 part by weight of divinylbenzene (hereinafter abbreviated as DVB). The solution was mixed with a tumbler blender to uniformly adhere the solution to the pellet surface.

Next, the pellets were heated in an extruder under a nitrogen atmosphere at 210
Pellets of the desired composition were obtained by extrusion at °C.

Example 2 In Example 1, the propylene-ethylene copolymer rubber had an intrinsic viscosity (135°C, in decalin) of 1.2 dll? The same procedure as in Example 1 was carried out except that the active polypropylene (hereinafter abbreviated as APP) was used.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the non-crosslinked rubbery substance was not blended.

Comparative Example 2 The same procedure as Comparative Example 1 was conducted except that the amount of peroxide (A) was 0.2 parts by weight.

The evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table ■)~
Shown in 4.

Claims (1)

[Scope of Claims] 1 (a) 90 to 40 parts by weight of peroxide crosslinked olefin copolymer rubber, (b) 10 to 60 parts by weight of peroxide decomposable olefin plastic (wherein 19 parts by weight)
a) + (b) selected to be 100 parts by weight) and (C) peroxide non-crosslinked hydrocarbon rubbery material (
A partially crosslinked thermoplastic elastomer characterized by dynamically heat-treating a mixture of 5 to 100 parts by weight (excluding polyimbutylene and imbutylene-isoprene copolymer rubber) in the presence of an organic peroxide. Method for manufacturing the composition. 2. The manufacturing method according to claim 1, wherein the peroxide crosslinked olefin copolymer rubber (2(a)) is an ethylene-propylene copolymer rubber or an ethylene-propylene-non-co-linked diene copolymer rubber. 3. The manufacturing method according to claim 2, wherein the ethylene-propylene-non-coterminous diene copolymer rubber is an ethylene-propylene-ethylidene norbornene copolymer rubber. 4(a) The production method according to claim 1 or 3, wherein the peroxide crosslinked olefin copolymer rubber has a Mooney viscosity ML1 +4 (100° C.) in the range of 10 to 120. s (b) The production method according to claim 1, wherein the peroxide decomposable olefin plastic is tactical polypropylene or a propylene-α-olefin copolymer. 6(b) Melt index of peroxide-degradable olefin plastics (ASTM-D1238-65T
1230°C) is 0.1 to 50. 7. The manufacturing method according to claim 1, wherein the organic peroxide is 1,3-bis(tert-butylperoxyisopropyl)benzene. 8. The manufacturing method according to claim 1, wherein the organic peroxide is blended in an amount of 0.05 to 1.0% by weight based on the material to be treated. 9(c) Peroxide non-crosslinked hydrocarbon rubbery substance is blended in an amount of 5 to 40 parts by weight based on a total of 100 parts by weight of components (a) and (b). Production method. IQ: The manufacturing method according to claim 1, wherein heat treatment is performed at a temperature of 150°C to 280°C.