KR20000002378A - Step by step condensing, dynamic sulfuring process for producing substantially unplasticized plastic/rubber compound - Google Patents

Abstract

PURPOSE: A process for preparing soft compound comprises three steps in which discharged gas during condensation is removed. CONSTITUTION: The process comprises three steps. Thus, i)first vulcanized product is prepared by vulcanizing first hardening acrylate rubber with first hardening agent followed by removing discharging gas in first condensation in presence of second hardening acrylate rubber which does not react with first hardening agent, ii)dense hard compound having hardness of above 40 Shore D is prepared by vulcanizing second rubber with second hardening agent followed by removing discharging gas in second condensation in presence of the plastic and the first vulcanized product, and iii) final soft compound having hardness of below 30 Shore D is prepared by vulcanizing added hardening acrylate rubber with added hardening agent followed by removing discharging gas in first condensation in presence of dense hard compound,

Description

Step-by-Step Condensation, Dynamic Vulcanization Method for Manufacturing Substantially Unplasticized Plastic / Rubber Blends

REFERENCE TO RELATED APPLICATION This application is partly a pending application of Ser. Nos. 08 / 686,782 and 08 / 686,798, filed July 26, 1996.

Polymer formulations with both elastic and thermoplastic, referred to as "thermoplastic vulcanizates" or "TPVs" (formerly referred to as "thermoplastic elastomers" or "TPEs"), are prepared by dynamic vulcanization to give the desired hardness / It provides flue, oil resistance and heat resistance, acid resistance and especially processability. For thermoplastic elastomers that are not physical blends, the properties are dependent on the properties of the respective components and the relative amounts of "hard" and "soft" phases provided by each component. To impart industrial value, hard phases can be provided in readily available industrial thermoplastic polymer resins, generally referred to simply as " plastic ". Most commonly the plastic is selected from polyesters, polyamides and polyolefins in which regions of the "soft" phase of the elastomer are dispersed in the continuous phase of the hard phase. TPVs containing polyolefins are not the object of the present invention, and the object of the present invention is a combination of vulcanizable (hereinafter simply referred to as "curable") rubbers to produce a relatively "soft" formulation controlled to a hardness of less than 30 Shore D Other “plastic” TPVs provided. The formulations are exceptionally resistant to oil swelling, residual compression.

The “rubber” phase is present in a relatively large weight ratio than the “plastic” phase, with low oil swellability and 30 Shore A-30 Shore D; In particular, there is a need in the market for blends of polar industrial thermoplastics containing dispersed "polar rubber" phases and continuous "plastic" phases having a hardness of 60-90 Shore A. These "polar rubber / plastic" blends of polyamide and acrylate rubbers, or polyester and acrylate rubbers are so viscous that they cannot be processed with conventional equipment, but when the substantial blends are made they are actually plasticized. That is, they cannot be used if they contain 30 parts by weight of plasticizer. By "unusable" it is meant that the plasticizer can flow out of the formulation at processing temperatures, generally 250 ° C, and can also flow out even at room temperature. The pellets that can be used should have a specific gravity of 0.9-1.2, in particular without the porosity (ie spongy) as proved to be a high moisture content even though the pellets took considerable time to dry. In particular, blends with polyolefins can be plasticized a lot, but not so large. However, vulcanized blends of acrylate rubbers containing nylon, PBT, and many other non-polyolefins do not produce the desired products unless they are substantially excluded from plasticizers or compatibilizers. "Substantially excluded" means that the blend contains up to 30 parts of plasticizer per 100 parts of rubber. If curable acrylate rubber is present in a large weight ratio (ie, "rubber rich"), the prior art methods can produce the desired porous blend. Acrylate rubbers, such as ethylene methyl acrylate copolymers, which contain repeating units derived from unsaturated monomers such as monoolefins having no curable functional groups (ie reaction sites), It is not "curable rubber". The aim is to provide a method of making a fully dense, preferably not a soft rubber-rich blend having a small weight ratio of "plastic phase" and a large weight ratio of "cured rubber phase", which blends Excellent tensile strength, residual compressibility, and oil swelling resistance. "Fully dense" means having a porosity that is inherently unmeasurable; In the form of pellets, the specific gravity of the pellets is equal to the specific gravity of the molded product from the pellets.

Polar formulations have been prepared by dynamic vulcanization using condensation reactions with the release of small molecules, but this reaction is relatively slow compared to the addition dynamic vulcanization of olefin rubber and polyolefin thermoplastics. The condensation reaction cannot be carried out in the presence of a plasticizer sufficient to promote the blending of the components under low temperatures that will adversely affect the physical properties of the blend. If the released small molecules are not treated, they become trapped in the formulation, resulting in a spongy substance. Therefore, it is impractical to adequately seal a batch mixer such as Banbury in order to add ingredients step by step and remove the products of the reaction, while these formulations are operated under the intended temperature of about 200 ° C-275 ° C, and the pellets It is common to pellet the dynamically vulcanized formulation in each step before introducing it into the next step and to prepare the mixture in separate, separate steps using a relatively short extended mixing-reaction zone. They are so expensive that they are produced in a continuous process with substantially adequate emissions.

Some barrels of a continuous mixer or mixer-extruder may be used in different lengths, but industrially available barrels should have a ratio of length (L) to diameter (D) of 80 or less, which is generally about 20 −. Is set in the range of 80. Thus, for all practical purposes, the continuous process for preparing the blend should be completed in a barrel with only 80 L / D, and if the barrel has an L / D of nearly 20, the process will be continuous. Since a condensation reaction is provided, it must be carried out in two or more separate steps to remove small molecules released.

Methods for preparing formulations containing non-polyolefin "plastics" are described in US Pat. Nos. 5,589,544 and 08 / 686,782 and 08 / 686,798, filed pending July 26, 1996, to Horrion. . By "non-polyolefin" plastics is meant that the plastic is substantially free from polyolefin chains. The term "plastic" refers to polyamides, polycarbonates, polyesters, polysulfones, polylactones, polyacetals. Acrylonitrile-butadiene-styrene (ABS), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), styrene-acrylonitrile (SAN), polyimide, styrene-maleic anhydride (SMA), and Refers to a resin selected from the group consisting of aromatic polyketones, of which the seedlings can be used on their own or in combination with others. Most preferred industrial thermoplastics are polyimides and polyesters.

In the Horrion '544 patent, the first step is to prepare a cured rubber concentrate (CRC) and the second step is to substantially combine the industrial thermoplastic material optionally with a compatiblizer. The CRC is made from a mixture of a curable elastic acrylic copolymer (“rubber”) and an acrylic “polymeric carrier” that does not react with the curing agent for rubber, and the rubber does not mix with the polymeric carrier.

1 diagrammatically illustrates a barrel (with outlet) for mixing of an extruder, in which two steps of the '554 patent are carried out continuously. In addition to the curing agent for the first curable rubber into the extruder of the first stage, the first curable rubber and the second curable rubber (called "carrier"), optionally a compatibilizer, and a dynamic vulcanized mixture (column 7 line 51 and column 8, text '544 over 11'). The CRC (compound A) is prepared by curing with only the first curable rubber. In a second step, the CRC is combined with plastics and addition additives and compatibilizers (see columns 9, lines 57-67, if necessary); The carrier may be crosslinked during mixing with the plastic using a different curing agent than that used to cure the curable rubber (column 9, lines 1-5). However, the plastic blend (Formula H) prepared directly in the second step as described by Horrion is sensitive to porosity. Porous (spongy) pellets of Formulation H suck water in the pellet forming step and are difficult to handle subsequent process steps. Prior to subsequent processing, it is impractical to dry the wet pellets. The pellets become pellets that are inadequate for injection molding by soaking in water, and when the blend is made with a desired plastic to rubber ratio, it is made of relatively soft TPVs using an extruder.

The '798 application states that when the first curable acrylic rubber and curable terpolymer are vulcanized in the presence of a curing agent and a plastic, they are formed into a blend having a single low temperature embrittlement point (LTB). The '798 application states that at least the first and second acrylic curable rubbers, each having a different functional group, are substantially crosslinked in plastic without the aid of a curing agent. Curable rubbers do not chemically react with each other, nor do they chemically react with industrial plastics. "Compatibility" means that the rubbers form a mixture comprising a second phase which can coexist with the continuous phase without the use of a compatibilizer or surfactant. Typical acrylic rubbers have C ₁ -C ₁₀ combined with one or more groups selected from C ₂ -C ₃ olefins, carboxyl, hydroxyl, epoxy, halogen, and the like.

A method using a three-step process comprising continuous first and second condensation reactions, wherein a final blend having a hardness of less than 30 Shore D, preferably less than 90 Shore A, is used substantially without the use of plasticizers. Wherein the first step is to form a hard blend that is an intermediate with the first curable acrylic rubber, and the second step is known to form a second curable blend of other curable acrylic rubber in the intermediate hard blend. not. The first curable rubber has a functional group different from that of the second curable rubber.

As can be seen in the Comparative Illustrated Examples provided herein below, the formulations made in the two-step process indicated by Horrion of '544 are in the same relative amounts as the formulations made by the three-step method of the present invention. Despite having the same components present, they have significantly different properties.

The compositions indicated in the above-mentioned '544 and' 798 invention, comprising two or more curable rubbers in combination with a polar industrial thermoplastic (abbreviated as "plastic"), are physically processed in a three-step process including an intermediate product process step. The properties can be controlled and made completely compact. An important intermediate step is curing with only the first curable rubber to produce an intermediate, fully dense hard blend that is at least 40 Shore D. In the third step, when the second curable rubber is cured, the intermediate hard blend is in a microstructure that is further sensitive to controlled modification.

The three-step process has a functional group that can be cured by different curing agents (ie, each curing agent) having repeating units derived from unsaturated crosslinking monomers such as two or more respective monoolefins. Effective in one functional group, but not the other). This repeating unit of the crosslinking monomer may crosslink the chain of the polymer containing the acrylate repeating unit and the repeating units (if present) of the monomer for the non-acrylate copolymerization. Each rubber is cured by a continuous condensation reaction in which small molecules are released. Thus, the small molecules are simultaneously removed from the reaction zone while the rubbers are cured.

The three-step process requires step vulcanization via a continuous condensation reaction, and in a first step, a sufficient amount of the second rubber is used to obtain a dynamically vulcanized formulation in which the rubbers are present as a separated phase. . If only two rubbers are used in the final formulation, only a portion of the total amount of the second curable rubber to be mixed in the final formulation is used in the first step. In the first step in which no plastic is present, a first condensation reaction occurs during compounding the first curable rubber with the second curable rubber, but only the first curable rubber cures with the first hardener. Other rubbers with functional groups sensitive to the same first hardener may also be cured.

Thereafter, in the second step, in the presence of the plastic, a second condensation reaction takes place with the second hardener, whereby the second curable rubber present and any other rubber with functional groups sensitive to the same second hardener, if present )). The hard formulation, the intermediate thus produced, is completely dense, has a hardness of at least 40 Shore D, and may be as high as Shore D 80.

The third step is preferably introduced by combining sufficient additional curable rubber (“third rubber”) and additional curing agent (“third curing agent”) and preferably a cured first rubber and an uncured second rubber. To provide a completely compact final formulation. The third rubber does not necessarily have a functional group different from that of the first or second curable rubber. The functional group of the third rubber may be the same as the functional group of the first or second curable rubber, or may be different from both. When the functional group of the third rubber is the same as the second functional group, the second and third curing agents may have the same effect, and may be the same. The third rubber may be a mixture of first and second rubbers, the amount of the curing agent for each selected being based on what is desirable for the final nature of the vulcanizate.

Preferably, if only the first and second curable rubbers have been cured by the first and second curatives, the process is operated continuously in separate distinct steps or in steps within a single extended reaction zone, An additional amount of curing agent and second curable rubber and optionally combined with the first rubber are introduced into the third stage to produce an essentially essentially completely compact final formulation.

The blending is preferably in a reaction zone extending axially, in a single continuous passage, if the zone is long enough to simultaneously remove (small molecule) gases from the zone; Or where the available zone is relatively short, it is carried out in two separate passages which simultaneously remove gases generated in the respective passages. Typical reaction zones have an L / D ratio in the range of about 20-80 and control substantially about 30 Shore A-30 Shore D, preferably 40 Shore A-90 Shore A, in the substantially absence of plasticizer (generally processed oil). To produce a new final formulation with a given hardness. The L / D ratio and the choice of final formulation generally determine whether the process for producing the formulation should be continuous or performed in separate steps.

More specifically, the three-stage vulcanizate is prepared by the first condensation reaction of the first rubber affected by the first hardener in the presence of an initial amount of second rubber not affected by the first hardener ( Preferably the relative amounts of the first and second rubbers are in the range of first stage condensation of 1: 2-2: 1). The first condensation generates a first small molecule, such as HCl or water, and causes the production of the first stage vulcanizate. In a second step, the second rubber is cured by two curing agents in the presence of plastic in a second condensation reaction to release the second small molecule, intermediate having a hardness of at least 40 Shore D, preferably at least 40-80 Shore D It produces a hard blend that is water and a completely dense blend. The plastic is the small weight ratio of the total amount of the first and second rubbers used in the hard formulation as an intermediate, and in the second step, the ratio (weight ratio) of the first and second rubbers to the plastic is less than 5 in total , Most preferably less than 4 and at least 1.5. In the third step, the intermediate hard formulation provides a medium, in which an additional, controlled amount of additional curable rubber is further condensed with additional hardener to cure and produce the desired final "soft" formulation; Preferably, in the third step, the ratio of all further rubbers which may be the same as or different from the first rubber, the second rubber and the second rubber to the plastic may be at least 2, more preferably 3-5.

Most preferably, the first, second and third stages are carried out continuously in a mixer-extruder long enough to facilitate completion of these three stages to discharge the final formulation, but the length of the extruder is a continuous process In case of insufficient restriction for the vulcanization treatment, the vulcanization treatment comprises: a first step of recovering the vulcanizate, preferably in pellet form; A second step of feeding the pellets into an extruder with plastics to produce an intermediate, hard formulation; Thereafter, the intermediate hard formulation may be carried out in a separate step, by a third step of combining the additional amount of additional curable acrylate rubber and additional curing agent. If the further rubber, ie the third rubber, has a functional group that can be cured with a third hardener different from the first and second hardeners, all the rubbers are preferably selected and compatible with each other. As additional (third) rubber it is most suitable to use an additional amount of said second rubber, an additional amount of said second curing agent together with the first rubber preferably cured. Since it is desirable to control and maintain the continuous curing of the rubber, it is not desirable to use rubbers with functional groups that react with one another and self-cure.

It is therefore a general object of the present invention to provide a three-step process for producing a vulcanized formulation that is substantially plastic in plastic and at least two (first and second) curable acrylate rubbers, wherein the process (I) preparing a blend of cured first rubber and uncured second rubber; (Ii) preparing an intermediate hard and fully dense blend, wherein when the hardness of the blend is present in the total amount of curable rubber, ie the second rubber is vulcanized with the second curing agent in the second condensation reaction, Controlled by the amounts of the first and second curable rubbers in the mixture; (Iii) then the first and second rubber and the other further curable rubber or the same as either the first or the second, or the second rubber, or combinations thereof and further curing agents, first and second curing agents The additional curing agent, which is different from either or both, is added to the hard formulation, which is the intermediate, continuing the reaction to the third condensation reaction or the second condensation reaction to produce the final formulation. The continuous condensation reaction is achieved in particular in the same extended reaction zone. The nature of the first stage vulcanizate is controlled by the relative amounts of the first and second rubbers and the reaction conditions of the first stage; The nature of the hard formulation is controlled by the reaction conditions in the second stage and the relative amounts of plastic and second rubber relative to the first curable rubber; The properties of the final formulation are finely controlled by adjusting the reaction conditions in the third step and by adding additional curable rubber and additional curing agent.

Specific objects of the present invention generally include a hardness of less than shore D 30 as measured by ASTM test D-471; Oil swelling resistance of less than 10; Nylon 6 or its copolymeramides without substantial use of conventional plasticizers or compatibilizers conventionally used to plasticize the prior art formulations, having a residual compressibility of at least 85 after 70 hours at 150 ° C. Relatively soft blends of the same polyamides and acrylate rubbers; And polybutylene terephthalate (PBT) or copolymers thereof and relatively soft blends of acrylate rubbers.

The above-mentioned additional objects and advantages of the present invention will be best understood with reference to the following detailed description and prior art and schematic illustrations of preferred embodiments of the present invention.

1 diagrammatically illustrates the prior art Horrion '544 process in two successive steps in an extruder in which the final blend is recovered.

2A schematically illustrates the process of the present invention in two successive stages in an extruder in which an intermediate, fully dense hard blend is recovered.

Figure 2B schematically illustrates a third step of the process of the present invention, which is carried out by re-extruding a fully dense hard formulation which is an intermediate with additional curable rubber and curing agent for all uncured rubber.

Suitable thermoplastic polyamide resins are crystalline or amorphous high molecular weight solid polymers including homopolymers, copolymers and terpolymers having repeating amide units in the polymer chain. Commercial polyamides having a Tg or melting point (Tm) of at least 100 ° C may be used but those having a Tm of 160-about 280 ° C are generally preferred for use in fiber production or molding operations. Examples of suitable polyamides include polylactams such as nylon 6, polypropiolactam (nylon 3), polyenantholactam (nylon 7), polycapryllactam (nylon 8), polylauryllactam (nylon 12) and the like; Amino acid homopolymers such as polyaminoundecanoic acid (nylon 11); Polypyrrolidinone (nylon 4); Copolyamides of dicarboxylic acids and diamines such as nylon 6,6; Polytetramethylene adipamide (nylon 4,6); Polytetramethylene oxalamide (nylon 4,2); Polyhexamethylene azelamide (nylon 6,9); Polyhexamethylene sebacamide (nylon 6,10); Polyhexamethylene isophthalamide (nylon 6,1); Polyhexamethylene dodecanoic acid (nylon 6,12), etc .; Aromatic and partially aromatic polyamides; High polyamides or terpolyamides such as caprolactam and hexamethyleneadipamide (nylon 6 / 6,6) (eg nylon 6 / 6,6 / 6,10); Block copolymers such as polyether polyamide; Or mixtures thereof. Further examples of suitable polyamides, described in Kirk & Othmer's Encyclopedia of Polymer Science and Technology, 2nd edition, Vol. 11, pp. 315-476, are incorporated herein by reference. Preferred polyamides for use in the present invention are nylon 6, nylon 11, nylon 12, nylon 6,6, nylon 6,9, nylon 6,10 and nylon 6 / 6,6. Most preferred are nylon 6, nylon 6,6, nylon 11, nylon 12 and mixtures or copolymers thereof. Polyamides generally have a number average molecular weight of about 10,000-50,000, preferably about 30,000-40,000. The amount of polyamide in the blend is generally about 25-100, preferably about 30-90, preferably about 35-75 parts by weight per 100 parts by weight of total acrylic rubber.

Suitable thermoplastic polyesters include various ester polymers such as polyesters, copolyesters or polycarbonates, such as monofunctional epoxy endcapped derivatives and mixtures thereof. The various polyesters may be aromatic or aliphatic or combinations thereof and generally diols such as glycols having a total of C _2-6 , preferably about C _2-4 , in total C _2-20 , preferably about C ₃ Direct or indirect induction by reaction with aliphatic having _-15 or aromatic acid having a total of about C _8-15 . Generally, aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene isophthalate, polynaphthalene terephthalate, and the like, and end-capped epoxy derivatives thereof (for example, monofunctional epoxy polybutylene terephthalate) are preferred. . Various polycarbonates may also be used and carboxylic acid esters may also be used. Suitable polycarbonates are those based on bisphenol A, ie poly (carbonyldioxy-1,4-phenyleneisopropylidene-1,4-phenylene).

The various ester polymers also contain one or more polyester blocks and one or more rubbery blocks such as glycols with C _2-6 (eg polyethylene glycol) or polyethers derived from alkylene oxides with C _2-6 Block polyesters, such as the like. Preferred block polyesters are polybutyleneterephthalate-b-polyethylene glycols sold by the company DuPont as Hytrel.

Rather than a plurality of plastics, preferably only one plastic (eg polyamide or polyester) from a single general class is used, which is used in small amounts based on the total weight of the rubber in the formulation. The plastic is preferably less than about 10-50 parts by weight, more preferably about 20-40 parts by weight per 100 parts by weight of acrylic rubber. A high proportion of plastics in the formulation results in a formulation with too high hardness (ie 30 Shore D).

2A diagrammatically illustrates an extruder in which the first two steps are carried out continuously. In a first step, a rubber masterbatch (compound A) is prepared by combining the curable rubber 1 with less than the total amount of curable rubber 2 (used) using a curing agent 1 that cures only the first rubber. When using a plurality of first rubbers (called as they can be cured by the same first curing agent), the first rubber has a functional group to be condensed with reactive sites on adjacent chains of the same rubber, the condensation reaction being one of the rubbers. Or both (plural first) chains.

One or more functionalized first and second acrylic rubbers are generally compatible with each other and also with plastics, especially when it is a polyamide or polyester.

In a second step, the rubber masterbatch (Formulation A) is combined with the selected plastic and cured with a second curing agent (curing agent 2). Initiating a second condensation reaction with the functional group on the rubber and the reactive site on the adjacent chain of the same rubber with the second curing agent to obtain a completely dense hard blend as an intermediate and a plurality of second rubbers which can be cured by the same second curing agent. Condensation reaction proceeds with one and both (or all the plurality of second) rubber chains.

Figure 2B schematically illustrates an extruder in which the available extruder barrel is insufficient to perform all three stages, so that the third stage is performed separately instead of being run continuously in the same extruder. The hard blend (compound B), which is the intermediate recovered in the second step (FIG. 2A), is mixed with an additional third rubber (curable rubber 3) and a hardener for the third rubber. In this particular embodiment in which only two rubbers are used and part of the curable rubber 2 is already used in the first step, the formulation B is mixed with the curable rubber 2 and the curing agent 2 and dynamically vulcanized to obtain the final formulation. As mentioned above, in another embodiment Formulation B may be admixed with the blend of curable rubbers 1 and 2 and additional curing agents for each of them. In another embodiment, as shown, Formulation B is mixed with curable rubber 3 and curing agent 3 (for rubber 3) different from rubbers 1 and 2. A final blend with the desired properties is then obtained.

Preferred curable rubbers are copolymers of two or more monomers such as alkyl acrylates, lower olefins and acrylates having functional groups provided that at least one monomer has a curable functional group in the condensation reaction.

In alkyl acrylates, alkyl has C _1-10 , generally C _1-3 . Curable rubbers generally comprise a repeating unit having a functional group and another repeating unit selected from ethyl acrylate, butyl acrylate, ethylhexyl acrylate and the like.

When selecting repeating units derived from olefins the olefins preferably have C _2-6 and typical curable rubbers may contain ethylene, propylene or butylene repeating units and the molar ratio of such olefins to acrylate repeating units is generally Less than 2, preferably 0.5-1.5.

Preferred functional groups of each of the two or more acrylic rubbers are selected from halogen, carbonyl, epoxy, hydroxy.

Suitable comonomers which provide pendant carboxylic acid groups include C _2-15 , preferably C _2-10 unsaturated acids. Examples of acid functionalized acrylic rubbers include terpolymers of ethylene-acrylate-carboxylic acids such as Vamac G from DuPont, and various carboxyl functional acrylates in particular sold by Nippon-Zeon. The proportion of rubber having repeating units having functional groups that can be cured in the condensation reaction (by weight) is less than about 10 mol%, preferably about 0.5-4% by weight, based on the total weight of the repeating units.

Suitable comonomers which provide pendant epoxy groups are oxirane acrylics in which the oxirane group is alkyl having 3 to about 10 carbon atoms and the ester group of the alkylate has C _1-10 (specific example is glycidyl acrylate) Unsaturated oxiranes such as rate. Another group of unsaturated oxiranes are various oxirane alkenyl ethers in which the oxirane group has 3 to about 10 carbon atoms and the alkenyl group has 3 to about 10 carbon atoms, a specific example being allyl glycidyl ether. Examples of epoxy functionalized acrylic rubbers include, in particular, acrylate AR-53 and acrylate AR-31 from Nippon-Zeon.

Suitable comonomers which provide hydroxyl groups include C _2-20 , preferably C _2-10 unsaturated alcohols. A specific example of a hydroxy functionalized acrylic rubber is Hytemp 4404 from Nippon-Zeon.

Preferred rubbers with functional groups are C _2-3 -olefins, C _1-4 -acrylates and terpolymers of acrylic acid or methacrylic acid. The olefin is present at about 35-80 mole percent, preferably about 45-55 mole percent, the acrylate is present at about 10-60 mole percent, preferably about 37-50 mole percent and the carboxylic acid is about 0.5-10 mole %, Preferably about 2-8 mole%. Representative commercial copolymers are Vamac G, Vamac LS, Vamac GLS or Vamac 6796 manufactured by DuPont.

The rubber is cured at each stage in the presence of an effective amount of at least one curing agent present in an amount sufficient to reach substantially complete curing of the rubber (ie, at least 90%, although a lower degree of curing of about 80% may be acceptable). Curing degree is easily measured by the amount of acrylic rubber which does not dissolve in toluene at 20 ° C. Suitable crosslinkers cure each rubber to covalently bond reactive groups. Preference is given to using compounds containing nitrogen-containing crosslinkers such as amines and preferably two nitrogen crosslinkers such as diamines. Examples of suitable crosslinkers include various maleimides, various diisocyanates such as toluene diisocyanate, various isocyanate terminated polyester prepolymers and various polyamines such as methylene dianiline. Moreover, various epoxides, such as diglycidyl ether of bisphenol A, can be used.

Very preferred curing agents are amine terminated polyethers exemplified by the Jeffamine ED-series polymers available from Texaco. Another class of curing agents are diamine carbamates exemplified by hexamethylenediamine carbamates such as Diak # 1 sold by DuPont.

The amount of curing agent used is generally about 0.5-12 parts by weight, preferably about 1-5 parts by weight per 100 parts by weight of the particular rubber to be vulcanized.

Optionally, with regard to the curing agent, accelerators may be used to reduce the curing time of two or more functionalized acrylic rubbers. Suitable accelerators include various fatty acid salts that do not crosslink the functionalized rubber compound. Often these compounds also act as lubricants. Fatty acid salts generally have 12 or 14 to 20 or 25 carbon atoms. Suitable cations include alkali and alkaline earth metals (ie, groups 1 and 2 of the periodic table) and various transition metals (eg, groups 11 and 12 of the periodic table). Specific examples of accelerators include salts of sodium, potassium, magnesium, calcium, zinc and the like and mixtures of fatty acids such as palmitic acid, stearic acid, oleic acid and the like, with potassium stearate and magnesium stearate being preferred. The amount of accelerator used is 10 parts by weight or less, preferably about 0.1-4 or 5 parts by weight, most typically about 0.5-1.5 parts by weight, per 100 parts by weight of rubber to be cured.

Preferred first rubbers are Vamac terpolymers having repeating units having carboxyl reactive curing sites and preferred second rubbers are acrylate rubbers having repeating units having chloroacetate reactive curing sites. Thus, in the first step, only the carboxyl group is cured to obtain a vulcanizate in which the chloroacetate group is not cured. Although the first stage blend may have two Tg, it may or may not have a single low temperature embrittlement point (LTB) depending on the specific reaction group of each rubber and the relative amounts of each.

In the second step a hard formulation is obtained in which the plastic is in continuous phase upon addition of the hardener for the plastic and the second rubber.

In the final step, the final blend prepared upon the addition of a greater amount of rubber to be cured and the curing agent for the rubber is completely dense and soft.

In the following exemplary examples, everything shown in parts is parts by weight.

EXAMPLE

Example 1

Rubber with a carboxy group, specifically about 52: 45: 5 weight ratio of ethylene, methyl acrylate, and acrylic acid, Vamac VMR-6796, a polymer of the same weight ratio with chloroacetate groups, specifically, about It is blended with Hytemp 4051CG, a copolymer of 95: 5 weight ratio of ethyl acrylate and lower alkyl (C ₁ -C ₄ ) vinyl chloroacetate. The mixture is combined with adducts of inert inorganic or organic fillers to remove Formula 2 which is released during curing in a Banbury mixer with Diak # 1 (hexamethylenediamine carbamate), a curing agent for Vamac, to form Formulation A. Examples of inorganic fillers include calcined clay, titanium dioxide, silica and talc; Examples of organic fillers include crushed peanuts, cashew husks, coconut charcoal, saturated hydrocarbons and fluorocarbon polymers.

67.5 parts of Formulation A are mixed with 40 parts of nylon 6 Utramid B3 and dynamically vulcanized in the presence of tertiary amine curing agent (ACM curing agent Hytemp SC-75), lubricants, processing aids and antioxidants, in a drying hopper-dryer. After 4 hours of drying at 230 ° F., Hard Formulation B, made into pellets, is prepared.

Thereafter, 50 parts of Formulation B are mixed with 50 parts of Formulation A, which are dynamically vulcanized in the presence of a tertiary amine curing agent (ACM curing agent Hytemp SC-75), lubricants / fillers, processing aids and antioxidants in a double-screw extruder. To produce the soft formulation C. Formulation C gives a plastic / rubber ratio of 20/80 which gives completely dense pellets with unexpectedly good oil swellability and residual compressibility. Residual compressibility shown here below is based on compression molded plague.

The components in Formulation A, and the relative amounts of each, are illustrated as follows:

Vamac, VMR-6796 50 Hytemp 4051CG 50 Vamac Curing Agent, Diak # 1 0.5 Inert organic fillers 12 Sum 112.5

The components in Formulation B, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 Nylon 6, Ultramid B3 66.7 ACM Curing Agent, Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Sum 190.7

The nature of Formulation B is illustrated as follows:

Ultimate tensile strength (psi) 3113 (21.5 Mpa) Elongation at Break (%) 125 100% modulus (psi) 3022 (20.8 Mpa) Residual elongation (%) 66 Hardness (Shore A / D) 59D Oil Swelling Rate (%) 70 hours @ 125 ℃ 1.4 Residual Compression Ratio (%) 70 hours @ 150 ℃ 95.6

The components in Formulation C, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 Nylon 6, Ultramid B3 25. ACM Curing Agent Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Santicizer 79TM 10. Sum 159.

The nature of Formulation C is illustrated as follows:

Ultimate tensile strength (psi) 1168 (8.1 Mpa) Elongation at Break (%) 155 100% modulus (psi) 953 (6.6 Mpa) Residual elongation (%) 26 Hardness (Shore A / D) 82A Oil Swelling Rate (%) 70 hours @ 125 ℃ 4.6 Residual Compression Ratio (%) 70 hours @ 150 ℃ 83.3

Example 2

In a similar manner as described in Example 1 above, the same components as above are blended into the final soft formulation in the same relative amount as above (plastic: rubber = 20: 80). However, using a lower relative amount of polyamide in a polyamide / rubber mixture of 30/70 to obtain an intermediate hard blend in step 2 results in a harder blend of softer intermediates resulting in only slightly more rigid final blends. And the above properties were proved to be virtually the same.

The components in Formulation A, and the relative amounts of each, are illustrated as follows:

Vamac, VMR-6796 50 Hytemp 4051CG 50 Vamac Curing Agent, Diak # 1 0.5 Inert organic fillers 12 Sum 112.5

The components in Formulation B, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 Nylon 6, Ultramid B3 42.9 ACM Curing Agent, Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Sum 190.7

The nature of Formulation B is illustrated as follows:

Ultimate tensile strength (psi) 1962 (13.5 Mpa) Elongation at Break (%) 140 100% modulus (psi) 1781 (12.3 Mpa) Residual elongation (%) - Hardness (Shore A / D) 45D Oil Swelling Rate (%) 70 hours @ 125 ℃ 5.3 Residual Compression Ratio (%) 70 hours @ 150 ℃ 91.5

The components in Formulation C, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 Nylon 6, Ultramid B3 25. ACM Curing Agent, Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Santicizer 79TM 10. Sum 159.

The nature of Formulation C is illustrated as follows:

Ultimate tensile strength (psi) 1170 (8.1 Mpa) Elongation at Break (%) 138 100% modulus (psi) 1010 (7.0 Mpa) Residual elongation (%) 27 Hardness (Shore A / D) 85 A Oil Swelling Rate (%) 70 hours @ 125 ℃ 5.2 Residual Compression Ratio (%) 70 hours @ 150 ℃ 75.5

Example 3

In a similar manner as described in Example 1 above, the same rubber components are combined with polyester to obtain the final soft blend. The relative amounts of all components are maintained as described above except that the plastic is polyester instead of nylon.

The components in Formulation A, and the relative amounts of each, are illustrated as follows:

Vamac, VMR-6796 50 Hytemp 4051CG 50 Vamac Curing Agent, Diak # 1 0.5 Inert organic fillers 12 Sum 112.5

The components in Formulation B, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 Nylon 6, Ultramid B3 66.7 ACM Curing Agent, Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Sum 190.7

The nature of Formulation B is illustrated as follows:

Ultimate tensile strength (psi) 985 (6.8 Mpa) Elongation at Break (%) 73 100% modulus (psi) - Residual elongation (%) - Hardness (Shore A / D) 43D Oil Swelling Rate (%) 70 hours @ 125 ℃ 7.1 Residual Compression Ratio (%) 70 hours @ 150 ℃ 79.7

The components in Formulation C, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 Nylon 6, Ultramid B3 25. ACM Curing Agent, Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Sum 149.

The nature of Formulation C is illustrated as follows:

Ultimate tensile strength (psi) 608 (4.2 Mpa) Elongation at Break (%) 200 100% modulus (psi) 486 (3.4 Mpa) Residual elongation (%) 12 Hardness (Shore A / D) 73A Oil Swelling Rate (%) 70 hours @ 125 ℃ 9.5 Residual Compression Ratio (%) 70 hours @ 150 ℃ 53.9

Example 4

In a similar manner as described in Example 3 above, the same components as above are combined with the final soft formulation in the same relative amounts (plastic: rubber = 20: 80). However, using a lower relative amount of polyester in the polyester / rubber mixture of 30/70 to obtain the hard blend as an intermediate in step 2, a soft blend as a soft intermediate is produced, yielding only a slightly harder final formulation. And the above properties were proved to be virtually the same.

The components in Formulation A, and the relative amounts of each, are illustrated as follows:

Vamac, VMR-6796 50 Hytemp 4051CG 50 Vamac Curing Agent, Diak # 1 0.5 Inert organic fillers 12 Sum 112.5

The components in Formulation B, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 Nylon 6, Ultramid B3 42.9 ACM Curing Agent, Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Sum 166.9

The nature of Formulation B is illustrated as follows:

Ultimate tensile strength (psi) 697 (Mpa) Elongation at Break (%) 166 100% modulus (psi) 657 (4.5 Mpa) Residual elongation (%) 15 Hardness (Shore A / D) 86A Oil Swelling Rate (%) 70 hours @ 125 ℃ 11.6 Residual Compression Ratio (%) 70 hours @ 150 ℃ 70.8

The components in Formulation C, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 PBT, Celenex 2002 25. ACM Curing Agent, Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Sum 149.

The nature of Formulation C is illustrated as follows:

Ultimate tensile strength (psi) 625 (4.3 Mpa) Elongation at Break (%) 194 100% modulus (psi) 469 (3.2 Mpa) Residual elongation (%) 10.3 Hardness (Shore A / D) 63A Oil Swelling Rate (%) 70 hours @ 125 ℃ 11 Residual Compression Ratio (%) 70 hours @ 150 ℃ 69.6

Example 5

Comparison of the formulations prepared by Horrion's two-step method and three-step method:

In the following two methods for making the final blend of two curable rubbers and nylons, each is properly discharged and made in an extruder except that the Horrion blend is produced in two steps (as shown in FIG. 1), The formulations of the invention are prepared in an additional three steps that provide for re-extrusion of the hard formulation, a two-stage intermediate, so that an additional cured rubber concentrate is added (as shown in FIGS. 2A and 2B).

In a method similar to that described in Example 1 above, Vamac GLS, a copolymer of about 50 mol% ethylene, 45 mol% methyl acrylate, and about 5 mol% acrylic acid, was prepared using Hytemp 4051CG (copolymer of ethylene acrylate / vinyl chloroacetate). (Weight ratio of about 95: 5) in the same weight ratio. The mixture is cured in a Banbury mixer with Diak # 1 and an inert organic filler and the vented gas is removed to yield Formulation A.

Formulation A was dynamically blended with Ultramide B3 nylon 6 in a two-step Horrion process (compound A: ratio of Ultramide B3 = 4.5) to yield Formulation H. Formulation A is also used during the three step process where more than twice the amount of nylon 6 relative to the amount of Formulation A used (Formulation A: Ultramid B3 = 1.69) to produce Formulation B, without adding plasticizer As a result, a completely dense hard blend is produced.

The components of Formulation H and Formulation B are as follows:

Formulation H Formula B Formula A 112.5 112.5 Nylon 6, Ultramid B3 25. 66.7 Hytemp SC-75 3.5 3.5 Inert organic fillers 4. 4. Naugard 445 2. 2. Kemamide S221 2. 2. Santicizer 79TM 10. 0. Sum 159. 190.7

Formulation H is vulcanized in the presence of a tertiary amine curing agent (ACM curing agent, Hytemp SC-75), lubricants / fillers, processing aids and antioxidants in a double-screw extruder to obtain a plastic / rubber ratio of 20/80. The pellets of Formulation B (produced in step 2) are completely compacted and have a hardness of at least 40 Shore D. When Formulation H is in pellet form for use in an injection molding machine, the pellets are spongy and generally wet, so that they are about 5 times less than the time required for the dry pellets of Formulation B or C (see below) under the same drying conditions. It needs 10 times longer time.

In a manner similar to that described in Example 1, the intermediate hard formulation B was dynamically vulcanized in the presence of an ACM curing agent Hytemp SC-75, a lubricant / filler, a processing aid and an antioxidant in a double-screw extruder to produce a soft formulation. Get C Formulation C gives a 20/80 plastic / rubber ratio which gives a completely dense pellet.

The components in Formulation C, and the relative amounts of each, are illustrated as follows:

Formula A 112.5 Nylon 6, Ultramid B3 25. Hytemp SC-75 3.5 Inert organic fillers 4. Naugard 445 2. Kemamide S221 2. Santicizer 79TM 10. Sum 159.

The properties of Formulation H and Formulation C are illustrated as follows:

Formula C Formulation H Ultimate tensile strength (psi) 972 (6.7 MPa) 856 (5.9 MPa) Elongation at Break (%) 184 248 100% modulus (psi) 682 (4.7 MPa) 595 (4.17 MPa) Pellet properties Fully compact Porosity Shore A 76 61 Oil Swelling Rate (%) 70 hours @ 125 ℃ 7 6.7 Residual Compression Ratio (%) 70 hours @ 150 ℃ 70 63

The effect of the present invention is generally: hardness less than shore D 30 as measured by ASTM test D-471; Oil swelling resistance of less than 10; Nylon 6 or its copolymeramides without substantial use of conventional plasticizers or compatibilizers conventionally used to plasticize the prior art formulations, having a residual compressibility of at least 85 after 70 hours at 150 ° C. Relatively soft blends of the same polyamides and acrylate rubbers; And relatively soft blends of polybutylene terephthalate (PBT) or their copolymer esters and acrylate rubbers.

Claims (14)

(i) curing the first curable acrylate rubber with the first curing agent in the first condensation reaction in the presence of a second curable acrylate rubber that does not react with the first curing agent to remove the released gas and simultaneously release the first vulcanizate. Getting steps (ii) curing the second rubber with a second curing agent in a second condensation reaction in the presence of the plastic and the first vulcanizate while simultaneously removing the released gas to form a completely dense hard formulation which is an intermediate having a hardness of at least 40 Shore D. Steps to and After (iii) additional amount of curable rubber is cured with additional curing agent in the condensation reaction in the subsequent condensation reaction in the presence of the intermediate, completely dense hard formulation, with substantially no plasticizer and a hardness of less than 30 Shore D. Obtaining the Final "Soft" Blend In a continuous step comprising a process for producing a vulcanized blend of an industrial thermoplastic (“plastic”) and two or more first and second curable acrylate rubbers. The intermediate according to claim 1, wherein the amount of plastic is sufficient to provide a continuous phase in which the vulcanizate is dispersed, and the intermediate amount is determined by the relative amount of the plastic present when the second rubber and the second rubber are vulcanized. Hardness How to control the hardness of a formulation. The method of claim 1. In said third step, said additional curable rubber is a blend of said first and second curable rubbers and said additional hardener comprises a curing agent for both said first and second rubbers. The method of claim 1, wherein in the third step, the additional curable rubber is the same as the second curable rubber and the additional curing agent is the second curing agent. The method of claim 1, wherein in the third step, the additional curable rubber is a third rubber different from the first and second curable rubbers and the additional curing agent is for the third rubber. 3. The method of claim 2, wherein the second rubber of the first step accounts for a small weight ratio relative to the total amount of rubber in the final blend. (i) curing the first curable acrylate rubber with the first curing agent in the first condensation reaction in the presence of a second curable acrylate rubber that does not react with the first curing agent to remove the released gas and simultaneously release the first vulcanizate. Getting steps (ii) curing the second rubber with a second curing agent in a second condensation reaction in the presence of the plastic and the first vulcanizate while simultaneously removing the released gas to form a completely dense hard formulation which is an intermediate having a hardness of at least 40 Shore D. Steps to and After (iii) additional amount of curable rubber is cured with additional curing agent in the condensation reaction in the subsequent condensation reaction in the presence of the intermediate, completely dense hard formulation, with substantially no plasticizer and a hardness of less than 30 Shore D. Obtaining the Final "Soft" Blend A vulcanized blend of industrial thermoplastics (“plastics”) and two or more first and second curable acrylate rubbers produced in three steps by: 8. The formulation of claim 7 having a hardness of about 30 Shore A to 30 Shore D. 9. The method of claim 8, wherein the amount of plastic is sufficient to provide a continuous phase in which the vulcanizate is dispersed, and the intermediate amount is determined by the relative amount of the plastic present when the second rubber and the second rubber are vulcanized. A method of controlling the hardness of a hard formulation that is water. The method of claim 8, wherein in the third step. Wherein said additional curable rubber is a blend of said first and second curable rubbers and said additional curing agent comprises a curing agent for said first and second rubbers. The blend of claim 8, wherein in the third step, the additional curable rubber is the same as the second curable rubber and the additional curing agent is the second curing agent. The formulation of claim 8, wherein in the third step, the additional curable rubber is a third rubber different from the first and second curable rubbers and the additional curing agent is for the third rubber. The blend of claim 9 wherein said second rubber of said first step comprises a small weight ratio relative to the total amount of rubber in said final blend. The formulation of claim 8, wherein the formulation has a hardness of about 60 Shore A to 90 Shore A.