JPS6213371B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to ethylene copolymers. More specifically, the present invention provides ethylene, carbon monoxide, a flexibilizing monomer,
Concerning copolymers with a fourth monomer containing pendant epoxy groups. Ethylene polymers are characterized by low polarity and low reactivity. They are similar to waxes in this respect and therefore have low dielectric constants and are soluble in hot oils, hot waxes and hot hydrocarbons. They are also known to be very inert. For some applications, ethylene polymers can be modified to make them flexible,
It is desirable to impart greater polarity to the ethylene polymers and make them available for reaction with other resins. The incorporation of unsaturated organic esters such as vinyl acetate or acrylates into the ethylene polymer can impart a lower degree of polarity and some flexibility to the ethylene polymer.
However, to provide a high degree of polarity, high levels of ester are required, which adversely affects the advantages of long ethylene chains, such as low cost, good low temperature behavior, etc. Therefore, it is desirable to increase the polarity of ethylene copolymers while retaining the hydrocarbon chain as the primary characteristic of ethylene copolymers. However, ethylene copolymers modified to be more flexible and more polar can still be relatively unreactive. Consider now the technology related to thermosets and especially blends with other polymers. Commercially available thermosetting resins such as phenolic resins, epoxy resins, etc. have been found to be useful because they retain their performance at elevated temperatures. This retention of performance is related to the crosslinking or curing effect present in the structure of the thermosetting resin used. However, this retention of high temperature performance is accompanied by high stiffness and brittleness, which makes it desirable to reduce the stiffness, or if some stiffness is desired, to increase the stiffness. It is desirable to reduce the stiffness by imparting toughness. The obvious solution of blending flexible polymers into thermosetting resins has not been successful to our knowledge. Molecular compatibility is never achieved; desirable properties of thermosets are lost. According to the invention, substantially (a) 40 ethylene units
~90% by weight; (b) 2-20% by weight of carbon monoxide units; (c)
selected from the group consisting of esters of unsaturated monocarboxylic or dicarboxylic acids with 3 to 20 carbon atoms and vinyl esters of saturated carboxylic acids with acid groups having 1 to 18 carbon atoms; and and (d) monomer units selected from the group consisting of glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether. A new copolymer comprising 0.2-15% by weight is provided. Preferred new copolymers contain, in addition to (a) ethylene and (b) carbon monoxide, (c) vinyl alkanoates, such as vinyl acetate, vinyl propionate, vinyl butyrate; Alkyl acrylate and alkyl methacrylate having;
A monomer copolymerizable with the above (a) and (b) selected from the group consisting of: and the above epoxy-containing monomer. Certain preferred copolymers are made from (a) ethylene, (b) carbon monoxide, (c) vinyl acetate, and (d) glycidyl acrylate or methacrylate. The above preferred copolymer has the following weight % unit (a)
Contains ~(d): (a) 45-90, more preferably 50-70, (b) 5-20, more preferably 7-18, (c) 10-33, even more preferably 20 -30, (d) 0.4-9, more preferably 1.5-6. The copolymer usually has a melt index in the range 0.1-3000, preferably 5-500. Since the copolymer is a simple addition copolymer produced from the above monomers in the presence of a free radical polymerization catalyst as described below, its main chain is composed of carbon-carbon covalent bonds. is clear. In preparing the copolymers of the present invention, commercially available ethylene, carbon monoxide, and 100% pure unsaturated monomers (c) and (d) are first used and a continuous configuration for polymerization (make-- A feed stream is used to supply the The reaction vessel used is capable of withstanding high pressures and temperatures and is equipped with a high speed motor-driven stirrer and a pressure relief valve as well as jacketed walls for circulating heating or cooling fluids to control temperature. The carbon monoxide and other monomers are pumped into the ethylene monomer feed stream at reactor pressure and then the mixture of monomers, together or separately, is pumped into the reactor at reactor pressure. Catalyst is optionally pumped into the reactor through separate feed lines. The mixture of copolymer and monomer exits the reactor;
The pressure then decreases as the mixture flows into the separator. The monomer leaves the separator and is either decomposed or pumped for recycling to the reactor with the constituent monomers. The molten copolymer leaves the separator in a stream, is cooled, and is further processed, eg, the copolymer can be cut into appropriately sized particles and placed into suitable containers for shipping. . Ethylene, carbon monoxide, monomer (c) to reactor
and (d) and the catalyst flows are carefully controlled so that they enter the reactor in a constant continuous molar ratio and at the same rate as product and unreacted monomers are removed from the reactor. The speed and molar ratio are
The product copolymer contains 40-90% by weight of ethylene units, 2-20% by weight of carbon monoxide units, and 5-5% of monomer (c) units.
40% by weight and 0.2-15% by weight of monomer (d) units. To maintain the reacting monomers in an intimate mix throughout the reactor, at least
Effective agitation is provided at a rate of 0.25 horsepower. Reactor temperature should be at least 140°C. The reactor temperature is about 155-300°C, most preferably 155-225°C.
Keeping the reactor pressure within 5000 °C
-60,000 psi, preferably within the range of about 20,000-35,000 psi. The copolymer of the present invention is characterized in that the contents of the reactor are kept homogeneous in terms of weight ratios of ethylene, carbon monoxide and monomers (c) and (d) such that a solid copolymer of the present invention is produced. is important in the production of
None of the monomers should be depleted so that no less than all the monomers are reacting. Since different monomers react at different rates, more reactive monomers will react at a greater percentage within a given period of time. As a result, the ratio of monomer feed rates will be different from the desired ratio of these monomers in the resulting copolymer. For example, carbon monoxide reacts about five times faster than ethylene, so that when 10% ethylene is incorporated into the polymer, about 50% carbon monoxide is present in the polymer. The conditions required to make a particular copolymer will vary depending on the reactivity of monomers (c) and (d); for example, vinyl acetate reacts at about the same rate as ethylene, whereas Other monomers such as methyl methacrylate react at about the same rate as carbon monoxide or faster. The epoxy-containing monomer (d) can react at various rates between the reaction rate of ethylene and the reaction rate of carbon monoxide. The free radical polymerization catalyst used in this method is:
It can be any of the catalysts commonly used in the polymerization of ethylene, such as peroxides, peresters, azo compounds, or percarbonates. Selected compounds within these groups are dilauroyl peroxide, di-t-butyl peroxide, t-butyl perisobutyrate, t-butyl peracetate,
α,α′-azobisisobutyronitrile and other compounds with corresponding free radical activity. Typically, the catalyst is dissolved in a suitable inert organic liquid solvent or mixture of solvents such as benzene, kerosene, mineral oil. Typical catalyst levels i.e. about 25 to 2500 ppm based on the weight of monomer fed to the reactor;
Preferably about 75-500 ppm is used. For purposes of this invention, it is desirable to understand the nature of thermoset resins and the molecular properties of blends of high polymers. Thermosetting resins such as phenolic resins are manufactured as low molecular weight polymers for processing into the desired form prior to the curing step. (These resins cannot be molded after curing). The low molecular weight resins may be liquids, or if solid at room temperature they become fluids when melted. This is in contrast to conventional thermoplastics, which have very high molecular weights and high melt viscosities. When attempting to disperse a high molecular weight thermoplastic into the low viscosity curable resin, blending can only be achieved if the thermoplastic is truly soluble in the low molecular weight liquid. Otherwise, the thermoplastic resin remains in the liquid as relatively large particles. Therefore, the first requirement of the present invention is to find a molecular structure that provides a thermoplastic resin that is soluble in the liquid thermosetting resin. Curing of a thermosetting resin occurs when thermosetting molecules are chemically bonded through sites that are present on average at more than two sites per molecule. When non-reactive thermoplastic polymers are dissolved in the thermoset, these thermoset molecules quickly move around and displace the thermoset during curing. The thermoplastic polymer is thereby forced out of the solidifying thermosetting composition. As a result, a two-phase system is formed. One phase is a hard, brittle thermoset matrix. The second phase consists of previously melted thermoplastic resin. Therefore, the second requirement of the present invention is
The goal is to introduce reactive epoxy groups into the thermoplastic copolymer that provide sites for the thermoplastic copolymer to participate in the curing process. The thermoplastic copolymer thereby tightly bonds into the cured thermoset resin matrix. In summary, thermoplastic resins are intended to serve as useful modifiers to thermoset resins. To be effective, it must be dispersed on a molecular scale, i.e., it must be dissolved in the thermoset resin before curing; and it must remain substantially dispersed in the thermoset resin after curing. Must. Another point that must be recognized is that there are two useful degrees of variance from the points discussed above. One is when the thermoplastic resin is sufficiently dispersed that the resulting blend is transparent after curing. Films molded and cured from such blends are more flexible than unmodified thermosets. It has a moderate and useful degree of elongation before the sample fails, but when the sample fails, it fails brittle without much energy absorption. However, it is well known in the art that rubbery impact modifiers for rigid thermoplastics should be finely dispersed as a separate phase tightly bound to the rigid phase. On the other hand, it is much more difficult to make thermosetting resins tough. The present invention is based on the discovery that the structure of copolymers can be adjusted to achieve a similar effect; that is, the copolymers of the present invention are designed such that they are only partially soluble in uncured thermosets. It also includes the discovery that it can be regulated. In this case, after curing, the small agglomerates of the thermoplastic resin of the invention can absorb impact energy, but in reality they are bonded via reactive sites to the cured thermoset matrix. That's why it works that way. The copolymers of the present invention may be used to make curable blends with an effective amount of a solid organic thermoset resin selected from the group consisting of phenolic resins, such as phenol formaldehyde resins; epoxy resins, and melamine formaldehyde resins. I can do it. The term "phenolic resin" refers to thermosetting phenolic-aldehyde resins, such as those prepared from phenols, cresols, e.g. m-p-cresol mixtures, p-cresol or cresylic acid, resorcinols and aldehydes such as formaldehyde and furfural. It is meant to include them. One-step (Resol) or two-step (Novolak) versions are useful (US Pat. No. 3,438,931). Also useful are phenol-formaldehyde resins modified with alkylphenols (eg, cresol), polyhydric phenols (eg, resorcinol, hydroquinone, etc.), or polyphenols (eg, bisphenol A). These curable blends contain the copolymer 1
99% and 1 to 99% thermosetting resin. Copolymer is 5-95% in the blend
present and thermosetting resin in the blend from 5 to 95
% is preferred. Particularly preferred ranges are 10-50% copolymer and 90-50% thermosetting resin. Before curing the curable blend,
It can be formed into sheets, blocks for molding purposes, or fibers. The curable blend can be in solid form that can be ground to a powder and then formed into molded or shaped articles, films, coatings or fibers before being cured. The cured composition in the form described above can be obtained by heating the curable composition, for example, in an oven, mold, or the like. The curable blends described herein can be filled with conventional fillers used in thermosetting systems. These fillers may be wood flour, asbestos, silica, glass fibers, cotton flock, mica, cloth flour and cord, rags, carbon black, or metals such as iron, lead, copper, and the like. The curable blends can be used to make flexible, semi-rigid or rigid films, coatings, fibers, moldings, foams and adhesives. The invention is further illustrated by the following examples. Percentages are by weight unless otherwise specified. Examples 1-4 Ethylene, carbon monoxide, vinyl acetate, and the fourth monomer listed in the table are mixed at the feed ratios listed in the table, and the resulting mixture is then mixed with catalyst of the type and amount listed in the table. A copolymer of the above monomers was prepared by feeding the above monomers into a highly stirred reaction vessel of 700 c.c. Reactor pressure and temperature and conversion of monomer to polymer are also shown in the table. Reactor residence time was 4.5 minutes. The melt index of the polymers reported in the table was determined according to ASTM D1238-65T, Condition E.

[Table] Example 15 Novolac phenol resin (Hooker
Durez 14000, a powdered two-step phenol containing approximately 7% hexamethylenetetramine, supplied by Durez Division of Chemical Company.
A blend containing 15% of the copolymer of Example 2 (formaldehyde resin) was made by dissolving both polymers in tetrahydrofuran.
The blend was dried on a hot platen and then pressed into a 2 mil film. Pressing film
Cured at 165° C. for 15 minutes at 20,000 psi pressure.
The cured film from this blend is clear, indicating good compatibility, and can be bent almost 180 degrees before breaking. This result is in contrast to the behavior of films from unmodified cured novolac phenolic resins, which are very brittle and break under very small strains. The compatibility properties of this blend contrast with those obtained using ethylene/vinyl acetate/glycidyl methacrylate copolymers without copolymerizing carbon monoxide. When this second copolymer is used, an opaque, incompatible blend is obtained, indicating that a carbon monoxide component is essential. The ratio of monomer units in this copolymer is 71/
It was 22/7. Example 16 A solution blend containing 35% of the polymer of Example 2 and the novolac phenolic resin of Example 15 was made. This blend was pressed into 3″ x 3″ x 1/8″ bars and cured at 150°C for 10 minutes. The bars were cut to 2 1/2″ x 1/2″ x 1/8″. It was made into a bar. The Izot impact strength of these bars is compared to 0.25 t.lb/inch for unmodified phenolic resin.
It was 0.39t.lb./inch. Example 17 A 50/50 blend was made from solution using the copolymer of Example 3 and the novolac resin of Example 15. The uncured film, ie, the cast from the solution, is clear, indicating compatibility. This film was cured in an air oven at 110° C. for 20 minutes to obtain a transparent and flexible film. This film can be folded and creased without cracking. The cured film was placed in a beaker containing boiling acetone. This sample remained a film after stirring for 30 minutes, indicating complete curing. Example 18 A 50/50 blend was made on a two roll mill at a temperature of 75°C. 15 g of the polymer of Example 3 was added to Durez
Blend with 15 g of powdered one-step phenolic resin (Resol) supplied as 26164. A 10 mil film was melt pressed from this blend and found to be hazy. This indicates only partial compatibility. This blend was pressed into a bar and the bar had an Izot impact strength of 2.5. This is a very high value for a cured polymer. Example 19 15 g of the polymer of Example 3 was added to a powdered two-step phenolic resin (novolac) Durez 22091, sold by Hooker Chemical Co., containing no curing agent.
I kneaded it with 15g. The blend was pressed into a 10 mil film and then held in the press at 150°C for 1 hour to cure. The film was transparent, indicating compatibility, and insoluble in boiling tetrahydrofuran, indicating cure. Example 20 A 50/50 solution blend was made from the polymer of Example 3 and the novolac phenolic resin described in Example 15 containing 8% hexamethylenetetramine. Press a 10 mil film at 100℃ and adjust the temperature to
Raised to 150°C for 30 minutes. The film was transparent. The tensile properties of this film are tensile strength
2150 psi; elongation 60%; tensile modulus 18000 psi. When the fractured specimen was returned to its original position, the above elongation was found to be >95% elastic (ASTM D-1708-66 [0.2″/min, crossbed speed]). Example 21 With 0.5 g of the polymer of Example 1, an epoxy equivalent weight of about 190 and at 25°C.
1.5 g liquid diglycidyl ether of bisphenol A with a viscosity of 13000 psi (Epon, sold by Shell)
(828) was used to create a solution blend in tetrahydrofuran. 0.15 g of the curing agent triethylenetetramine was added. The solution was evaporated to dryness to form a film. The film was cured by heating on a steam bath for 1 hour. The film was transparent and could be folded without exhibiting brittleness. This behavior was in contrast to the brittle behavior of a control film made similarly without the addition of the Example 1 polymer. Example 22 50% of the polymer of Example 2 and 50% of a melamine-formaldehyde resin, hexamethoxymethylmelamine (Cymel 301) sold by American Cyanamid.
A solution blend was made in tetrahydrofuran of As a curing catalyst, p-toluenesulfonic acid was added at a concentration of 0.25% by weight excluding the solvent. This solution was coated onto aluminum, dried and cured at 150°C for 1 hour. The resulting film was very slightly hazy, flexible, and could be folded without cracking. A similar film containing only melamine formaldehyde resin and catalyst was also coated onto aluminum and cured. In contrast, this film was very brittle and cracked when the aluminum was bent. Examples 23-29 A series of tetrapolymers were prepared according to Examples 1-14. Polymer composition and reaction conditions are summarized in the table.

[Table] Comparative Example 1 and Examples 30 and 31 Wood flour and two-step (novolac) phenolic resin
Created a blend of phenolic resins based on a 50/50 blend. 8 parts of hexamethylenetetramine was added during the blending step to act as a curing catalyst. All blends contain 40% wood flour for comparison purposes. The inventive polymer was added to replace a portion of the phenol, except in Control Example 1, where an additional amount of novolak phenolic resin was used in place of the inventive tetrapolymer. Bar 1/8″×1/
2" x 5" molded at 100°C and cured at 160°C for 10 minutes. The results shown in the table show that higher flexural strengths and higher flexural strains at failure can be obtained with only a slight reduction in the elastic modulus (Example 30); It can be found that a significant increase in the bending strain at failure, accompanied by a decrease in the bending strength, and a large decrease in the elastic modulus can be obtained (Example 31).

[Table] Mar
31 Example 26 20 320 10 4.5
Tetrapolymer
Comparative Example 2 and Examples 32 and 33 Blends of phenolic resin containing wood flour similar to Examples 30 and 31 were molded into 1/8" thick blacks and cured as described above. The black was tested by dropping a spear with a weight of 1/4 pound (Gardner Test) to determine the height at which the crack appears on the back side of the black. It has been shown that a 2-3 fold increase can be achieved depending on the structure of the conjugate.

[Table] Lapolymer
33 Tet of Example 26 25 3.2
Lapolymer
Comparative Example 3 and Examples 34 and 35 A commercial grade phenolic resin is compounded with medium length glass fiber filler and various additives for electrical applications, among others. This formulation is coded Durez23570. The two tetrapolymers of the invention were added at 20% of the total composition. For comparison, 20% pure novolac resin was added to obtain a control with the same amount of fillers and additives. Samples were molded, cured, and tested for electrical properties. In the table it is shown that the electrical properties are not impaired to a significant extent. However, the volume resistivity is improved by at least 5 times.

Table: Example 36 When the phenolic resin is less than 50% of the blend, an elastic cured product can be created.
Examples of such behavior are shown in the table. Note that the percent elongation to the point of failure is 100-200%, and the elastic recovery of this elongation after failure is approximately 90%.

Table: Comparative Example 4 and Examples 39-41 A commercially available epoxy resin was filled with glass fibers and pelletized for use in injection molding (Fiberite E2748). Blends were made and evaluated as shown in the table.

【table】

Claims (1)

[Claims] 1 (a) 40 to 90% by weight of ethylene units; (b) 2 to 20% by weight of carbon monoxide units; (c) esters of unsaturated monocarboxylic or dicarboxylic acids of 3 to 20 carbon atoms and acid groups selected from the group consisting of vinyl esters of saturated carboxylic acids having from 1 to 18 carbon atoms;
5 to 40% by weight of monomer units copolymerizable with (a) and (b); and (d) 0.2 to 15% by weight of monomer units selected from the group consisting of glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether; An ethylene copolymer having a melt index of ~3000 and having a carbon-carbon covalent bond in its main chain.