KR830000062B1 - Thermoplastic Elastic Mixture of Olefin Rubber with Polyolefin Resin - Google Patents

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Description

Thermoplastic Elastic Mixture of Olefin Rubber with Polyolefin Resin

The present invention relates to a thermoplastic elastic composition composed of a mixture of a polyolefin resin and a cured olefin rubber.

It is well known that Hoffmann points out that EPDM rubbers cured with phenolic curing agents have good mechanical properties, but curing EPDM rubbers with phenolic curing agents has not been used commercially.

BACKGROUND OF THE INVENTION Thermoplastic elastomeric (clastoplastic) compositions consisting of a mixture of polyolefin resins and cured EPDM rubbers and exhibiting excellent physical properties with improved tensile strength are well known. [Reference: Belgian Patent No. 844,318, filed January 20, 1977 and United States Patent Application No. S / N No. 679,812, filed April 30, 1976. The improved composition described above is economical because it is an oil or carbon for extender. It can be extended with black, which adds cost and improves processability and oil resistance. However, compositions having better oil resistance have been desired to be able to work at high temperatures when exposed to organic solvents or oils. It has surprisingly been found that mixtures of polyolefin resins with rubbers cured with phenolic curing agents are superior in oil resistance compared to mixed compositions of EPDM rubbers cured with other curing agents.

According to the present invention, an elastic composition composed of a polyolefin resin and an EPDM rubber cured with a phenolic curing agent is a tough and strong elastic composition that can be processed into a thermoplastic material, and other similar compositions where the rubber is cured with a curing agent such as sulfur or peroxides. Compared with the improved characteristics. The composition of the present invention has improved oil resistance, and the compression set and the product made with the composition have a smooth surface and do not exhibit bloom phenomenon. The use of phenolic hardeners reduces many of the bad odors in production and processing and produces a fragrant product.

The composition of the invention is particularly easy to extrude and has excellent paintablilty, ie paint adheres well to the surface. Besides these advantages, other advantages are shown in the following description.

The elastic composition of the present invention comprises a phenolic curing agent such that (a) an amount of crystalline thermoplastic polyolefin resin sufficient to impart thermoplasticity to the composition and (b) about 5% or less of rubber can be extracted in boiling xylene. It consists of an amount of EPDM rubber sufficient to impart rubbery elasticity to the composition which cured the rubber. The relative component ratios of polyolefin resin and EPDM rubber are not absolute because they depend on factors such as shape, molecular weight, or molecular weight distribution of polyolefin resin or EPDM rubber and depend on the presence of other components in the composition. For example, inert fillers, such as carbon black or silica, reduce the operating range, while extender oils or plasticizers increase the range of operating rates. In general, the present invention is composed of a mixture of polyolefin resin, which is the present composition, and EPDM rubber of (a) 25 to 75 parts by weight of crystalline thermoplastic polyolefin resin and (b) 75 to 25 parts by weight per 100 parts by weight of rubber. Preferred compositions contain such that the polyolefin resin does not exceed 50% by weight of the total composition.

EPDM rubber in the composition of the present invention is fully cured. A convenient way to assess the state of cure is to measure the amount of rubber dissolved in cyclohexane. When less than 3% of the gum is extracted in cyclohexane at 23 ° C, the rubber is considered to be fully cured. Soluble components with rubber are mentioned in the following detailed description. Another method of assessing the degree of curing of rubber is to measure the amount of rubber dissolved in boiling xylene.

The rubber is considered to be fully cured when extracted from xylene boiling up to 5%, preferably up to 3%, more preferably up to 1% of the rubber in the mixture.

The composition of the present invention mainly consists of polyolefin resin and cured EPDM rubber and contains a negligible (if present) polyolefin resin and a graft copolymer of EPDM rubber. Thus, the compositions of the present invention should not be confused with the graft copolymers described in Hartman, US Pat. Nos. 3,862,056 and 3,909,463.

It was confirmed that there is no graft copolymer in the composition of the present invention, because the hardened EPDM rubber is hardly soluble in boiling xylene and can be separated from the polyolefin resin in the mixture, whereas the Hartmann graft copolymer is boiling. This is because it is almost completely soluble in xylene. In a preferred composition of the present invention, the polyolefin resin is almost all dissolved in boiling xylene and less than about 3% of the rubber is extracted. Infrared analysis of the free polyolefin resin fraction (soluble in boiling xylene but insoluble in xylene at room temperature) reveals little or no grafted EPDM rubber as 2 wt% or less.

Vulcanizable rubbers are classified as thermosets even if they are thermoplastic in the uncured state, because they become unprocessable through an irreversible thermosetting process. The products of the present invention, although further processed, contain irreversible thermoset rubbers (although they have very small particle sizes) because they are phenolic in terms of the time, temperature and amount to obtain a fully cured product. This is because it is made from a mixture of a rubber treated with a curing agent and a polyolefin resin, and in fact, the rubber is gelled (insoluble in organic solvents) to have properties in a hardened state. The thermoset state of the bulk composition can be prevented in the composition of the present invention by simultaneously kneading and curing the mixture.

Therefore, the thermoplastic elastomeric composition of the present invention is a temperature at which the EPDM rubber, softened or molten polyolefin resin and the mixture and the phenolol curing agent are mixed and then the mixture can be kept in application and promotes curing until it is fully cured. It can be prepared by grinding in a conventional grinding device such as Banbury mixer, Brabender mixer and mixing extruder.

The components other than the curing agent are mixed at a temperature sufficient to soften the polyolefin resin, and more typically at a temperature above the melting point of the resin when the resin is crystalline at normal temperatures. After the molten resin and the EPDM rubber are well mixed, phenolic curing agent (ie, phenolic curing agent and curing activator) is added. Generally, the cross linking reaction is heated and comminuted at the curing temperature to complete in minutes. The time required for the completion of the crosslinking reaction depends on the curing temperature and the type of EPDM rubber or the curing agent system used. Suitable temperatures for curing are the melting point of the polyolefin resin (about 120 ° C. for polyethylene, 175 ° C. for polypropylene) to 250 ° C., typically 225 ° C. within 150 ° C. Preferred curing temperatures are between 170 ° C. and 200 ° C. To obtain the thermoplastic composition, it is important to continue mixing without interruption until curing occurs. Curing after stopping the mixing yields a thermosetting composition that cannot be further processed.

The particular result obtained in the dynamic curing process described above is due to the action of the selected rubber curing system. Phenolic curing agent systems make it possible to obtain improved compositions that have not been obtained conventionally. It is essential to select a phenolic curing agent system capable of fully aging rubber using a curing activator in combination with a phenolic curing resin. Similarly, a process using a phenolic hardener system is typically a “EPDM rubber” consisting of a rubber consisting of two monoolefins and at least one olefin, ie ethylene, propylene and a non-conjugated diene containing residual unsaturated groups in the side chains. It can only be used in polyolefin terpolymer rubber and the like. Gumumu having few unsaturated groups is not suitable because it is not sufficiently crosslinked by a phenolic hardener. Moreover, at least 25% by weight of polyolefin resin in the mixture is required to produce a processable thermoplastic elastomer. Thus, even before fully gelling, a dynamically cured, non-processable composition can be obtained and the tensile strength can be slightly improved by bran. However, nobody wants unnecessary results and tries to incompletely understand the interactions of the factors that influence the results.

To determine if they are useful in preparing the products of the present invention, it can be seen by doing some simple experiments using the rubber and phenolic economies available.

All new products can be processed into continuous sheets by moving to a rolling roll of a rubber mill at temperatures above the softening point or crystallization point of the vesim phase in an internal mixer. The sheet can be reprocessed back into a plastic state (molten melt state) in the internal mixer when the temperature reaches the softening point or melting point of the polyolefin resin, but when the molten product is passed through the roll of the rubber grinder it is again a continuous sheet. Form. Moreover, the thermoplastic composition sheet of the present invention can be cut into pieces, and compression molded into a single smooth plate in which the pieces are fully knit or fused. Thereby, the above-mentioned "thermoplastic" may be referred to below. In addition, the elastic composition of the present invention can be further processed to produce a product by extrusion, injection molding, blow molding, thermoforming and the like.

The amount of rubber that can be extracted from the mixture is used to determine the degree of curing. The improved elastomeric composition of the present invention comprises a mixture of compounds, such that up to about 3% by weight of rubber in the cured composition is extracted in cyclohexane at 23 ° C., or up to about 5% by weight of rubber in boiling xylene. It is prepared by curing. In general, the smaller the amount extracted, the better the properties, and most preferably the rubber is not extracted in the organic solvent (1% by weight or less). The percentage of soluble rubber in the cured composition is usually immersed in cyclohexane at 23 ° C. for 48 hours in 2 mm thick specimens, or refluxed and dried for half an hour in xylene boiling film specimens. However, it measures by modifying suitably based on knowledge of a composition. The modified initial and final weights are used by subtracting the weight of components soluble in solvents, such as extender oils, plasticizers, low molecular weight polymers and polyolefin resins soluble in cyclohexane, in addition to the curable rubber at the initial weight. Insoluble pigments, fillers, etc. are subtracted from both the initial and final weights.

Materials present in uncured rubber that are not soluble in acetone are considered non-crosslinkable components of the rubber and this amount is reduced in the rubber when calculating the percentage of soluble rubber in the cured composition. EPDM rubber is up to 5% by weight, typically 0.5 to 2.0% by weight, dissolved in acetone.

Of course, a sufficient amount of phenolic hardener should be used to completely cure the rubber. The minimum amount of phenolic curing agent required to cure the rubber depends on the type of rubber, the type of phenolic breakthrough agent, the type of curing accelerator and the curing conditions (temperature, etc.). Typically, the amount of phenolic curing agent required to fully cure the rubber is 5 to 20 parts by weight per 100 parts by weight of EPDM rubber and preferably 7 to 12 parts by weight per 100 parts by weight of EPDM rubber. In addition, an appropriate amount of curing activator is used to completely cure the rubber. The preferred amount of curing agent is about 0.01 to 10 parts by weight per 100 parts by weight of EPDM rubber, and more may be used if necessary. "Phenolic curing agents" include phenolic curing agents (resins) and curing surfactants. However, from the fact that the amount of phenolic curing agent is used based on the content of EPDM rubber in the mixture, it should not be construed that the phenolic curing agent does not react with the polyolefin resin and no reaction occurs between the polyolefin resin and the EPDM rubber. Very important reactions may occur, but only to a limited extent. That is, almost no graph is formed between the polyolefin resin and the EPDM rubber. Almost all cured EPDM rubbers and polyolefin resins can be separated, separated from the mixture by hot solvent extraction (extracted with boiling xylene), and the infrared fractions of the separated fractions are graft copolymers between the EPDM rubber and polyolefin resins. Is slightly (if present, it is formed.

Any EPDM rubber that can be fully cured (crosslinked) with a phenolic curing agent is suitable for practicing the present invention. Suitable monoolefin terpolymer rubbers are amorphous rubbery terpolymers copolymerized with two or more alpha monoolefins, preferably at least one polyene, usually nonconjugated dienes, and are referred to in the specification and claims as "EPDM rubber". It is called. Preferred EPDM rubbers are those produced by the polymerization of two monoolefins, generally ethylene, propylene and smaller amounts of non-conjugated dienes. The amount of nonconjugated diene is 2 to 10 weight percent of the rubber. EPDM rubbers usable in the present invention are all possible as long as they can be fully cured by having sufficient reactivity with the phenolic curing agent. The reactivity of EPDM rubbers depends on the degree of unsaturation and the unsaturated form in the polymer. For example, EPDM rubbers derived from ethylidene and norrenene are more reactive to phenolic curing agents than EPDM rubbers derived from dicyclopentadiene. EPDM rubbers derived from 1,4-hexadiene are dicyclopentadiene. Lower reactivity to phenolic curing agents than EPDM rubbers derived from However, the difference in reactivity can be overcome by polymerizing a large amount of diene with low activity on rubber molecules. For example 2.5% by weight of ethylidene norbornene or dicyclopentadiene gives sufficient reactivity to allow EPDM rubber to be fully cured by phenolic curing agents containing conventional curing activators. In the case of EPDM rubber derived from hexadiene, at least 3.0 weight percent is required to obtain sufficient reactivity.

Suitable alphamonoolefins can be represented by the general formula CH ₂ = CHR, where R represents hydrogen or C _1-12 alkyl, for example ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 2,4,4-trimethyl-1-pentene, 3-methyl -1-hexene, 1,4-ethyl-1-hexene and the like. Preferred non-conjugated dienes include straight chains such as 1,4-hexadiene, 2-methyl-1,4-pentadiene, 1,4,9-tecatriene and 11-ethyl-1,11-tridecadiene. Cyclic, acyclic) dienes; Monocyclic dienes such as 1,5-cyclooctadiene, 1,4-cycloheptadiene and 1-methyl-1,5-cyclooctadiene; 5-ethylidenenorbornene, 5-methylene-2-norbornene-5-isopropylidene-2-norbornene and 2-methylbicyclo- (2,2,1) -2,5-heptadiene Crosslinked cyclic bicyclic dienes such as; Bicyclo (4,3,0) -3-7-nonadiene; Fused alicyclic bicyclic materials such as 5,6-dimethyl-bicyclo (4,3,0) -3,7-nonadiene and bicyclo (3,2,0) -2,6-heptadiene; Monocyclic substances substituted with alkenyl such as 4-vinyl-cyclohexene, 1,2-divinylcyclobutane and 1,2,4-trivinylcyclohexane; And tricyclic materials such as dicyclopentadiene.

Examples of the Invention Suitable grades of EPDM rubber are commercially available. (See Rubber world Blue Book 1975 Edition, Materials and Compoundding Ingredients for Rubber, p40-410)

Suitable thermoplastic polyolefin resins are crystalline, high molecular weight solid products obtained by polymerizing one or more monoolefins in a high or low pressure process. Examples of such resins are commercially available as isotactic and syndiotactic monoolefin polymer resins. Preferred olefins are ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1- Hexene and mixtures thereof. Commercially available thermoplastic polyolefin resins, preferably polyethylene or polypropylene, are preferably used in the present invention, with polypropylene being more preferred.

Any phenolic curing agent system that completely cures EPDM rubber can be used in the present invention. The basic component of such a system is a phenolic curable resin made by condensing an unsubstituted or substituted phenol with an aldehyde in an alkaline medium or by condensing the functional phenoldialcohol. Halogenated phenol cured resins are particularly suitable. Particularly recommended are phenolic curing agent systems consisting of phenolic resins, halogen donors and metal compounds, details of which are described in Giller's U.S. Patent No. 3,287,440 and U.S. Patent No. 3,709,840. Usually halogenated, preferably brominated phenolic resins (comprising 2 to 10% by weight of bromine) do not require a halogen donor, but iron oxide, titanium oxide, magnesium oxide, magnesium silicate, silicon dioxide, preferably zinc oxide, etc. Used in conjunction with hydrogen halide removers such as metal oxides, their presence promotes the crosslinking action of phenolic resins.

However, in the case of rubber which is not easily cured with phenolic resin, it is preferable to use a halogen donor and zinc oxide together. Processes for the preparation of halogenated phenolic resins and their use in hardener systems are described in US Pat. Nos. 2,972,600 and 3,093,613 and are also described in the patents described above by Giller and Gustin. Halogen donors are suitable as halogen donors, such as stannous chloride, ferric chloride, or paraffin chloride, polyethylene chloride, chlorosulfonated polyethylene and polychlorobutadiene (neoprene rubber).

As used herein, the term "enhancer" means a material that increases the crosslinking efficacy of a phenolic curable resin, and includes both metal oxides and halogen donors. More detailed phenolic curing agent systems are described in the following literature. [See Dibble. "Vulcanizing and Vulcanizing Agents" published by Hoffmann Palmerton Publishing Company] Suitable phenolic curing and brominated phenolic curing resins are commercially available, for example the trademark SP-1045 from Schenectadi Chemicals Incorporate. , CRJ-352, SP-1055 and SP-1056. Similar phenolic resins, which are functionally equivalent, are supplied elsewhere. As described above, a sufficient amount of curing agent should be used to completely cure the rubber.

The plastic elastic composition of the present invention can be modified by adding a component commonly used to the rubber olefin resin and mixtures thereof before or after vulcanization. Examples of these components include carbon black, silica, titanium dioxide, pigmented pigments, clays, zinc oxide, stearic acid, stabilizers, antidegradants, flame retardants, processing aids, adhesives, plasticizers, tackifiers, waxes, wood, Discontinuous fibers such as cellulose fibers and extender oils. Carbon black, extender and the like is preferably added before the dynamic curing (dynamic curing). Carbon black improves tensile strength and promotes phenolic curing agent activity. Extender oils can improve the oil swelling resistance, heat stability, hysteresis, cost and permanent strain of the plastic elastic composition. Aromatic, naphthenic and paraffinic extender oils are preferred. Addition of extender oils may also improve processability.

Suitable extender oils are described in the following literature. [Rubber World Blue Book, pp 145 190].

The amount of extender oil added depends on the desired properties, the upper limit depends on the compatibility of the particular oil and mixture components, and if the excess oil is yielded, it will exceed the limit. Typically, 5 to 300 parts by weight of extender oil is added per 100 parts by weight of the olefin rubber and the polyolefin resin mixture. Usually, 70 to 200 parts by weight of a weight oil is added per 100 parts by weight of rubber present in the mixture, and preferably 30 to 250 parts by weight per 100 parts by weight of rubber. The amount of weight oil depends, in part, on the type of rubber.

High viscosity rubbers require large amounts of oil. When preparing colored compositions of the present invention, colorless or white pigments (fillers, extenders, or reinforcing pigments) are used instead of carbon black.

For this purpose, silica, aluminum silicate, magnesium silicate, titanium dioxide and the like are suitable. Typically 5 to 100 parts by weight of white pigment is added to 100 parts by weight of rubber in the mixture. When carbon black is used, 100 parts by weight of EPDM rubber is added 40 to 250 parts by weight of carbon black, and usually 20 to 100 parts by weight of carbon black is added per 100 parts by weight of EPDM rubber and extender oil. The amount of carbon black depends in part on the form of the carbon black and the amount of extender oil used.

The composition of the present invention may be prepared by a method other than the method of dynamically curing the mixture of rubber / polyolefin resins. For example, the rubber is fully cured and powdered in the absence of polyolefin resin, dynamic or static, and then mixed at a temperature above the softening point or melting point of the polyolefin resin and resin. When the crosslinked rubber particles are small and well dispersed at an appropriate concentration, the composition of the present invention is easily obtained by mixing the crosslinked rubber with the polyolefin resin. Thus, “blend” refers to a mixture of crosslinked rubber particles in which the particles are small and well dispersed.

Mixtures outside the scope of the present invention have poor dispersion or too large particles, which are preferably pulverized by cooling grinding (to reduce the particle size below 50μ), preferably 20μ or less, more preferably 5μ or less. I can make it. After sufficient grinding or grinding, the composition of the present invention is obtained. Poor dispersion or too large rubber particles can be observed with the naked eye, and can also be found in molding sheets. Virtually no pigments and fillers. In this case, when crushed and re-molded, aggregates or large particles of rubber particles are not visually observed, and sheets with greatly improved mechanical properties can be obtained.

The plastic elastomeric composition of the present invention is useful for making products such as tires, hoses, belts, gaskets, moldings and molded parts. They are particularly useful for making products by extrusion, injection molding and compression molding, and are also useful for modifying thermoplastics, in particular polyolefin resins. The composition is mixed with the thermoplastic resin using a conventional mixing device. The nature of the modified resin depends on the amount of plasticized composition mixed.

Generally, the amount of plastic elastic composition is such that the modified resin contains 5 to 25 parts by weight of EPDM rubber per 95 to 75 parts by weight of the total resin.

The strains strain property of the composition of the present invention is measured according to the methods of ASTM D 638 and ASTM D 1566. The term "elastic material" described in the present specification and claims is extended to twice the original length at room temperature and then stretched for a given time (1 or 10 minutes) and stretched within the same time (1 or 10 minutes). It refers to a composition with a tension set that cannot return to less than 160% of its original length.

The compression set is measured by ASTM-D-395, Method B, which compresses the specimen at 100 ° C. for 22 hours. Oil swelling (% change in weight) was measured by ASTM-D-471, where the specimen was immersed in ASTM # 3 oil at 121 ° C. for 3 days. Particularly preferred among the compositions of the present invention are those in which the tension set is 50% or less and can be defined for rubber by ASTM Standard V. 28, P.756 (D-1566). More preferred compositions have Shore D hardness of 60 or less, 100% modulus (10% modulus) of 180 kg / cm 2 or less, and young's modulus of 2500 kg / cm 2 or less.

The present invention is described in detail as follows.

A master batch containing EPDM rubber, paraffin extender oil, carbon black, zinc oxide, stearic acid and antidegradants (when present) in the specified proportions (all parts by weight) is polypropylene and a brabender mixer at 80 rpm. The mixture is melted for 2.5 minutes at an oil bath temperature of 180 ° C. in a molten polypropylene to obtain a uniform mixture. Thereafter, the temperature of the brabender mixer is regarded as the temperature of the oil bath. After adding the phenolic curing agent for another 4 minutes in succession, the maximum Brabender consistency is reached.

The composition is recovered and compression molded at 210 ° C. Cool the sample to 100 ° C or below under pressure before withdrawing the specimen. Measure and record the properties of the molded sheet.

The data for the various compositions are shown in Table I. Blends 1-3 and 4-6 each contain other EPDM rubber as reported. Mixed raw materials 1 and 4 are for control, which do not contain a curing agent. Mixed raw materials 2 and 5 are compositions of the present invention cured with a phenolic curing agent. Blends 3 and 6 are compositions cured with a curing agent system as a control.

73 wt% ethylene, 4.4 wt% ethylidene norbornene, polydisper sity 2. 1, SP. gr. 0.86, mooney viscosity, 55 (ML + 121 ° C.).

121℃).2. 55 wt% ethylene, 4.4% ethylidene norbornene, complexity 5.2, SP. gr. 0.86, Mooney viscosity, 40 (ML 1 + 8

121 ° C.).

3. Low flow rate, general purpose, Sp. g. 0.902. 11% elongation.

4. Polymerized 1,2-dihydro-2,2,4-trimethylquinoline.

5. Brominated Methanol Phenolic Curing Resins.

6. 17.2 parts of sulfur, 10.3 parts of zinc dimethyl dithiocarbamate, 10.3 parts of tetraethylthiuram disulfide, 34.5 parts of 2-bis (benzothiazolyl) disulfide and 27.7 parts of dipentamethylidene thiuram hexasulfide.

EPDM rubbers in the blends 2,3,5,6 are fully cured. That is, the weight of the rubber extracted in cyclohexane or breaking xylene at room temperature is 3% or less based on the weight of the total rubber. This cured composition is an elastomer and can be processed as a thermoplastic and can be reworked without the need for regeneration as compared to a thermoset, fixed curable composition that cannot be processed as a thermoplastic. The data show that compositions made from EPDM rubbers containing large amounts of ethylene have high hardness. It can be seen that the compositions cured with phenolic cured resins have almost the same strain, while the environmental system is more effective for compositions containing low complex dispersion EPDM rubber. Compositions cured with phenolic cured resins have two advantages over compositions cured with sulfur curatives: high oil resistance (low oil swelling) and excellent compression set.

100℃)이다.The composition consisting of a mixture containing EPDM rubber as the main component is shown in Table II. Mixed raw material 1 contains no curing agent. Mixed raw material 2 is the composition of this invention hardened | cured with phenolic hardening resin, and mixed raw materials 3 and 4 are control compositions, respectively, which were hardened with the hardening | curing agent system and the peroxide hardening | curing agent. Polypropylene is as shown in Table I. EPDM rubber is a terpolymer composed of 69% by weight of ethylene, 8.3% by weight of ethylidene norbornene and average propylene, with a complex dispersion of 2.2 and a Mooney viscosity of 51 (Mooney Visc. ML 8

100 ° C.).

Except in the case of Mixed Raw Material 2, all processes are as shown in Table I. After 1 minute of addition of phenolic curing resin, zinc oxide is added. In mixed raw material 4, 0.6 weight part of tris (nonylphenyl) phosphites which are free radical removers are added after a maximum brabender viscosity is obtained.

This data shows that the composition cured with phenolic curing resin is better in oil resistance and compression set.

Flexible compositions containing large amounts of rubber and weight oil are shown in Table III. This process is as in Table I, except that the mixing is continued for 5 minutes after adding the curing agent.

Mixed raw material 1 is the control which does not contain a hardening | curing agent. Control raw materials 2, 4 and 6 are compositions of the present invention cured with phenolic curable resins, and mixed raw materials 3, 5 and 7 are compositions cured with sulfur curing systems.

From this data, it can be seen that the composition cured with phenolic curing resin is excellent in compression set and oil resistance. In addition, compositions cured with phenolic curable resins have a smoother surface upon compression or injection molding.

The surface of the extrudate and the parts molded from the composition cured phenolic curable resin is free of bloom and not sticky. Mixed raw material 6 containing a large amount of rubber exhibits excellent elasticity, that is, a low tension set and a low compression set.

The effect of hardener concentration is shown in Table IV. Processes and components are as shown in Table II. From this data, it can be seen that when the concentration of the curing agent is increased, the effect on the stress strain in the sulfur curing system is smaller than in the phenolic curing resin system. Tensile strength hardly changes even if the concentration of the curing agent changes in both cases. As the concentration of phenolic curing resin increases, modulus increases and elongation decreases, while the modulus and elongation hardly change as the amount of sulfur curing agent changes. At all concentrations, the compositions cured with phenolic curable resins are excellent in compression sets and have high oil resistance.

1. 63 wt% ethylene, 3.7 wt% ethylidene sorbbornene, complex dispersity 2.6, sp. gr. 0.90, Mooney viscosity. (ML-4, 125 ° C.) 50 terpolymers extended with 100 phr unpolymerized naphthenic oil polymerized.

2. Polypropylene and hardeners are shown in Table I.

3. Polymerized 1,2-dihydro-2,2,4-trimethylquinoline.

1 is shown in Table III.

2 is shown in Table I.

The inventive compositions cured with non-halogenated phenolic curable resins are shown in Table V. This process is the same as above. Mixed raw material 1 is a control which does not contain a curing agent. Mixed raw material 2 is a control containing phenolic curable resin but no curable activator. Blend 5 is another control containing a curing agent. Mixed raw material 3 contains dimethyl-p-nonylphenol (commercial phenolic curing resin under the trade name sp-1045). Blends 3 and 4 contain halogenated tin and chloro sulfonated polyethylene as halogen donors, respectively. This data shows that the curing activator must be used with a non-halogenated phenolic curing agent to completely cure the rubber. The presence of halogen donors (curing activators) actually increases tensile strength and significantly improves compression set and oil resistance. The high oil swelling degree of Blend 2 indicates that the rubber is only partially cured. Also from this data, it can be seen that compositions cured with phenolic curing agent systems containing halogen donors have better compression set and oil resistance than similar compositions cured with sulfur curing agents. Mixed raw materials 3 and 4 have a high tensile strength retention after being swollen by oil.

The experiments shown in Table VI indicate that a curing activator (zinc oxide) must be present to completely cure the rubber. This process is as in Table I but no master batch was used since the composition contained no carbon black or extender oil. The compositions of the mixed raw materials 1 and 2 were the same, except that the mixed raw material 2 did not contain zinc oxide. The average of two experiments with mixed raw material 2 is reported in Table VI.

The composition was extracted with boiling xylene to measure the degree of cure (cured rubber is insoluble in boiling xylene). A thin (about 0.05 mm thick) specimen is placed in boiling xylene.

1. 69 wt% ethylene, 8.3 wt% ethylidene norbornene, complex dispersion 2.1, sp, gr. 0.86, Mooney viscosity 50 (ML-8, 100 ℃)

2. Table I is as follows.

3. Dimethyl -p-nonylphenol (not halogenated).

121℃), 황으로 가황 가능하며 매우 빨리 경화된다.1. 55 wt% ethylene, 4.4 wt% ethylidene norbornene, complex dispersion 2.5, sp. gr. 0.86 Mooney viscosity, 70 (ML 1 + 8

121 ° C.), vulcanizable with sulfur and cures very quickly.

2 is shown in Table I-1.

After about 30 minutes, the membrane usually degrades. The xylene suspension is then filtered through a glass fiber filter having a pore size of 0.3 microns. All components except polypropylene are considered part of the cured rubber. The filtrate is cooled to room temperature to precipitate polypropylene (or crystalline graft copolymer) which is recovered by filtration.

Evaporate the second filtrate to dissolve it in xylene at room temperature (atactic polypropylene, low molecular weight polypropylene, amorphous ethylene-propylene copolymer, uncured rubber or amorphous polypropylene-EPDM rubber graft copolymer). Recover. The weight percent of the various materials recovered are reported together with the calculated theoretical values (in parentheses) of the EPDM rubber and polypropylene. The calculated value of the cured rubber is corrected taking into account the amount of material present in the uncured rubber. This correction (1.6% by weight of rubber) is the sum of 0.9% by weight of acetone solubles in uncured rubber and 0.7% by weight of cyclohexane (room temperature) insoluble in uncured rubber. Substances soluble in acetone are considered not to be crosslinked. Materials that are insoluble in cyclohexane at room temperature are considered polyolefin homopolymers. For example, in Blend 1, the calculated value of insoluble rubber in parentheses is 39.3 weight percent, which would be 39.6 weight percent unless corrected as indicated above. Similar corrections apply to all calculations. (In parentheses in tables Ⅶ-Ⅸ)

As a result of this data, it can be seen that the mixed raw material 1, which is a composition containing zinc oxide, has excellent tension set and compression set, low oil swelling degree, and no rubber is extracted in boiling xylene. This indicates that the rubber is fully cured. This also indicates the absence of graft copolymers. On the other hand, in compositions that do not contain zinc oxide, 32 percent of the rubber is extracted from boiling xylene.

This indicates that the graft copolymer is present or the rubber is only partially cured. From this data, it can be seen that in order to obtain a composition of the present invention containing a fully cured rubber, a curing activator must be used to promote a complete reaction between the EPDM rubber and the phenolic curable resin.

The composition of the invention having high hardness, containing carbon black and a large amount of polypropylene, is shown in Table VII.

A master batch containing rubber, carbon black, zinc oxide and stearic acid is mixed with polypropylene until the polypropylene is dissolved in a brabender mixer at 80 rpm, 180 ° C. to obtain a homogeneous mixture. Add phenolic cured resin and mix until the maximum Brabender hardness is reached, then mix for 3 more minutes. After recovering the composition into a sheet and put back into the brabender mixer, it is mixed for 2 minutes at 180 ℃. From this data, it can be seen that this composition is harder and harder than the composition of the above-mentioned table, which contains a large amount of rubber. The tension set point indicates that the elasticity of the composition is reduced. As solubility data, it can be seen that the rubber is completely cured given that the rubber is not dissolved in boiling xylene.

The order in which each component is added, in particular the order in which cure activators such as zinc oxide are added, is important. This is especially important when large amounts of zinc oxide are added without filler. This is shown in Table VII. The procedure is as in Table I but no master batch was used as there was no carbon black or extender oil. Each component was added in the order described.

1 is shown in Table VI.

In mixed raw material 1-5, zinc oxide is added before adding the phenolic cured resin, while in mixed raw material 6-9, zinc oxide is added after adding the phenolic cured resin. This data shows that when the zinc oxide is added to the phenolic resin earlier, the stress strain decreases as the amount of zinc oxide increases, and when the zinc oxide is added later, the amount of zinc oxide does not significantly affect the stress strain. It can also be seen that better compositions are obtained when zinc oxide is added later. Such compositions have a high degree of stress strain, excellent tensile and compression sets, and high oil resistance. As solubility data, it can be seen that the order of addition of zinc oxide has a marked effect on the degree of curing of the rubber. When zinc oxide is added before the phenolic curing resin, the amount of rubber dissolved in boiling xylene varies from 0 to 23 percent depending on the amount of zinc oxide in the composition (mixture 1-5), while zinc oxide is added later. The amount of rubber soluble in boiling xylene when boiling is less than 1% by weight of the rubber in the composition (mixture 6-9). In addition, as solubility data for cyclohexane at room temperature, it can be seen that the addition of zinc oxide prior to addition of the phenolic curable resin dissolves much of the rubber in the composition. The weight percentage of rubber dissolved in cyclohexane is corrected taking into account 0.9% by weight of the component dissolved in acetone of the uncured rubber. This correction is even greater considering the stearic acid which can be extracted in cyclohexane.

The study of the component ratios of EPDM rubber and polypropylene is shown in the following table. This composition contains only rubber, polypropylene, phenolic cured resin and zinc oxide.

It is shown in Table VI.

The amount of zinc oxide and phenolic curing agent is changed so that the ratio of the light breaker and the rubber is kept constant at the ratio of 2 parts by weight of zinc oxide and 10 parts by weight of phenolic cured resin per 100 parts by weight of rubber.

Rubber and polypropylene are filled in a brabender mixer at 180 ° C. and mixed at 100 rpm. The polypropylene is melted and after 3 minutes phenolic cured resin is added and mixing is continued for 1 minute. Zinc oxide is then added and mixing is continued for 4 minutes. The composition is recovered, put into a sheet, placed back into the brabender mixer and mixed for another 2 minutes. The composition is recovered from the mixer again into a sheet and compression molded at 220 ° C. All compositions are thermoplastics and mixed materials 1-4 are elastomers.

Mixed raw materials 5 and 6, which contain a large amount of polypropylene, are inelastic and necking occurs when samples are taken. In other words, the specimen is difficult to be in its original form. Over the entire range, the rubber is fully cured when the amount of rubber that is soluble in boiling xylene is less than or equal to 1% by weight of the rubber in the composition.

Colorable inventive compositions containing white pigment (magnesium silicate) and inventive compositions containing polyethylene are described in Table VII. Blend 1 contains 50 parts by weight of polypropylene, 40 parts by weight of magnesium silicate (filler grade), 0.5 parts by weight of stearic acid and 5.6 parts by weight of phenolic curing agent SP-1056. The preparation method is the same as in Table V, except that the magnesium silicate is completely dispersed before adding the phenolic curing agent. Zinc oxide is not needed when using magnesium silicate.

1. Table VI.

2. Uniform molecular weight fraction polyethylene, ASTM D 1248-72, type III, class A, class 5, melt index 0.3g / 10min, density 0.950g / cm 3.

Solubility data for cyclohexane shows that the rubber is fully cured. The composition of Mixed Raw Material 2 contained 40 parts by weight of EPDM rubber and 60 parts by weight of phenolic curing resin SP-1056. Rubber and polyethylene are charged to a Brabender mixer at 180 ° C. and then ground at 80 rpm until the polyethylene melts. Stearic acid and phenolic curing agent are added while mixing until a homogeneous mass is obtained. After addition of zinc oxide, the mixing is continued for another 2 minutes besides the time to reach the maximum defect degree (about 3 to 4 minutes). The composition obtained is thermoplastic and elastic. The solubility data shows that the rubber is fully cured.

The compositions of the present invention using various other curing activators are shown in Table II. EPDM rubber contains 50 wt% ethylene, 40.6 wt% propylene and 4.4 wt% dicyclopentadiene and has a complex dispersity of 6.0. Polypropylene is shown in Table I. Phenolic cured resin is added last. The control mixed raw material did not contain a curing activator. The nature of the composition indicates that the rubber is incompletely cured (or graft copolymer obtained). This is confirmed by cyclohexane solubility data. Mixed raw materials 2, 3 and 4 contain zinc oxide, zinc stearate and stannous chloride, respectively, as curing activators. The data shows that the rubber in the mixture is almost completely cured. The percentage of rubber dissolved in cyclohexane is corrected taking into account the fact that 1.38% by weight of uncured rubber is dissolved in acetone. The correction value is indicated by an asterisk. As mixed raw materials 4 and 5, it can be seen that when stannous chloride is used as an activator, non-halogenated phenolic curable resins can be used instead of halogenated phenolic curable resins, and the resultant plastic elastic compositions exhibit almost the same properties.

1. Halogenated Phenolic Curing Resin as in Table I

2. Non-halogenated phenolic cured resin as shown in Table IV.

It is important to use a curing activator (S) and to use it at an appropriate concentration. If no curing activator is used or used at an inappropriate concentration, the rubber will not fully cure. Uncured hardening deteriorates the properties of the mixture. At high concentrations of the activator, the curable resin reacts within itself (homopolymerization), especially when added before the phenolic curable resin, thereby depleting the curing agent system. Suitable activator concentrations depend on the type of activator, phenolic curable resin or rubber, the order of addition of the phenolic curable resin and activator, and the process temperature, but the degree of suitability can be readily determined by experiment.

The composition of the present invention in which the EPDM rubber contains different monomers is described in Table XII. Blends 1 and 2 are compositions containing EPDM rubbers containing rubbers which are unsaturated derived from ethylene norbornene (ENB). Mixed raw material 3-6 is a composition containing EPDM rubber having an unsaturated value derived from 1,4-hexadiene (1,4HD).

Mixed Raw Material 7 is a composition containing EPDM rubber derived from unsaturated unsaturated dicyclopentadiene (DCPD). These compositions are prepared by the same process as in Table I, but Blend 7 has a Brabender temperature of 170 ° C. In mixed raw materials 1-6, the curing activator is finally added. In mixed raw material 7, tin oxide is added, phenolic curing agent is added, and zinc oxide is added. Uncorrected calculation of insoluble rubber; The calculations inferred that all components were insoluble except polypropylene upon curing are given in parentheses. Starred values were corrected as follows. 4,13 and 1.38% by weight of unmatured rubber in blends 4 and 7 are soluble in acetone, respectively.

The uncured EPDM rubber used in Blend 6 does not contain acetone soluble components, but 2.52% by weight of the uncured rubber is insoluble in cyclohexane at 50 ° C., which means that a large amount of non-crosslinkable polyolefin polymer is present. From this data, it can be seen that all the compositions have excellent stress strains, and the complex dispersion of rubber does not have a significant effect on the degree of curing. All compositions exhibit the desired oil swellability and compression set. As solubility data, it can be seen that the rubber in all compositions is fully cured.

This can be explained by comparing the extrusion properties of the mixture cured with the improved soluble phenolic curing agent and the mixture aged with the curing agent of the present composition. For example, extrusion compositions similar to Mixtures 2 and 3 of Table I were 381 cm / s using a Davis-Standard extruder with a diameter of 3.81 cm equipped with a general purpose screw of 1 L / D running at 70 rpm. A tube with an outer diameter of 12.7 mm was produced by extruding through a die (20: 1 L / D) having an outer diameter of 12.7 mm × 9.53 mm inner diameter at a take off speed of minutes.

The size of the tube is maintained by weak internal air pressure and quenching with water. The temperature of the barrel is between 193 ° C. and excessive 232 ° C., which is sufficient to dissolve the polypropylene completely. It is performed at an intermediate temperature of about 216 ° C. Draw down ratio was also studied by measuring the integrity of the extensible composition under process temperature. The level drop rate is the ratio of the annular area of the die to the cross sectional area of the tube whose diameter has been reduced by not gradually increasing the take off rate. The results are summarized in Table III.

* Machine limit-not broken

From this data, it can be seen that a composition prepared by curing with a phenolic curing agent is higher in processability than a composition using a curing agent. Particularly with this data, it can be seen that compositions cured with phenolic resins can be extruded at a wide range of temperatures, and as shown in area ratios, tubes of a wide range of sizes can be produced.

The improved processability of the compositions of the present invention can be explained by comparing the extrudability of compositions similar to Mixed Raw Materials 6 and 7 in Table III. For example, the composition is fabricated 5 mm rods through a 5.08 mm rod die using a 2.54 cm diameter NRM extruder equipped with a 16: 1 L / D general purpose screw operated at 60 rpm.

The barrel temperature is 180 to 190 ° C to 210 ° to 220 ° C. The results are shown in Table IV. From the data, it can be seen that a composition with a phenolic curing agent can be extruded at higher speeds than a composition with a curing agent and a tube with a smoother surface can be produced.

The composition of the present invention consists of a mixture of polyolefin resins and small particles of dispersed crosslinked rubber, resulting in a strong composition that can be processed into a thermoplastic. The rubber particles preferably have a number average size of 50 mu and a weight average size of 50 mu. More preferably, the number average rubber particle size is 5 mu or less.

Although typical examples of the present invention have been described above, the present invention is not limited thereto, and modifications and variations may be made without departing from the spirit and scope of the present invention.

Claims (1)

A plastic elastomeric composition consisting of a mixture of a thermoplastic crystalline polyolefin resin and a cured EPDM rubber, wherein the EPDM rubber is cured with a phenolic curing agent.