Abstract:
Saturated and ethylenically unsaturated compounds containing carboxylic, amino or alcohol groups are reacted under mild conditions and in short process times with polycarbodiimides containing free isocyanate units to provide polymers with excellent properties. The unsaturated groups bonded to the polymers are particularly important because these groups provide reactive centers that can be crosslinked, either thermally or in the presence of catalysts that initiate polymerization or by radiation. The polymers can also be crosslinked either alone or by copolymerization with various unsaturated monomers. The resulting crosslinked or cured resins provide excellent properties such as hardness, high elongation, excellent toughness, high heat distortion temperatures and good corrosion resistance.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns the preparation of novel curable, ethylenically unsaturated polymers formed by reacting a polycarbodiimide having free isocyanate groups with compounds having active hydrogens and copolymerizable ethylenic unsaturation. The ethylenically unsaturated, active hydrogen compounds can be partially replaced with saturated compounds. 
     2. Description of the Prior Art 
     Vinyl copolymerizable thermosetting resins are in widespread commercial use. Of special interest are those resins, which are capable of rapid cure, and which have outstanding physical and thermal properties. 
     Most commercially available resins are products of polyester or epoxy chemistry. In general, the preparation of these resins requires high temperatures, several process steps, and long processing time. 
     U.S. Pat. No. 4,148,844 to von Bonin et al, discloses casting resins consisting of a mixture of polycarbodiimides in vinyl monomers which cure by heating to a temperature above 40° C. The polycarbodiimides are prepared by reacting polyfunctional or monofunctional isocyanates with a phospholane oxide catalyst. The unreacted or free terminal isocyanate groups of the resulting polycarbodiimides can be eliminated by reaction with an amine or alcohol. 
     U.S. Pat. No. 4,463,158 to O&#39;Connor et al discloses a liquid polymer composition which comprises a modified polyurethane oligomer containing ethylenic unsaturation and a free radical generating catalyst. The polyurethane oligomer is prepared by reacting an organic polyisocyanate with an isocyanate reactive group containing unsaturated monomer to obtain an isocyanate-terminated prepolymer of controlled molecular weight having a free isocyanate content of from about 0.5% to about 30%. The isocyanate-terminated prepolymer is then reacted with a polyol to produce a polyurethane oligomer of controlled molecular weight with terminal reactive unsaturation. 
     U.S. Pat. No. 4,367,302 to Le Roy et al discloses crosslinkable thermoplastic polyurethanes having isocyanate end groups and containing ethylenic side groups. These polyurethanes are obtained by reacting an organic diisocyanate with a saturated diol and an unsaturated diol. The ethylenic side groups in the polyurethane product are branched over the entire whole length of the linear skeleton of the polyurethane molecule. 
     U.S. Pat. No. 4,758,625 to Boyack et al discloses urethane crosslinked acrylic coatings. The polymer backbone exhibits the basic characteristics of acrylic polymers and contains at least 50% by weight of acrylic monomer. 
     U.S. Pat. No. 4,028,310 to Shafer et al relates to the preparation of polyisocyanate containing acylurea groups and, optionally, carbodiimide groups in the polyisocyanate polyaddition reaction carried out in the presence of diamine chain extenders. 
     U.S. Pat. No. 4,077,989 to Shafer et al relates to the production of modified isocyanates wherein compounds containing isocyanate and carbodiimide groups are reacted with carboxylic acids. 
     U.S. Pat. No. 4,174,433 and U.S. Pat. No. 4,192,925, both to Shafer et al, relate to polyols modified by guanidine groups, which are used as starting components for the preparation of polyurethane plastics. 
     U.S. Pat. No. 4,192,926 to Shafer et al relates to polyols modified by acylurea groups used as starting components in the preparation of foamed polyurethane plastics. 
     U.S. Pat. No. 4,192,927 to Shafer et al relates to polyols modified by phosphonoformamidine groups, for use as a starting component in the preparation of foamed polyurethane plastics. 
     U.S. Pat. No. 4,321,394 to Shafer et al relates to a process for producing addition compounds of compounds containing hydroxyl groups and carbodiimides substantially free from isocyanate groups, by reacting the components in the presence of an inorganic or organic tin compound used as the catalyst. 
     Ulrich et al, Journal of Cellular Plastics, September-October 1985, pages 350 to 357 reviews the chemistry and properties of low density polycarbodiimide foams and discloses suitable formulations, processing conditions, physical properties and small scale flame test results of the resultant polymers. 
     Williams et al, &#34;Carbodiimide Chemistry: Recent Advances&#34;, Chem. Rev., Vol. 81, pages 589 to 636 (American Chemical Society 1981) is a comprehensive literature review of carbodiimide chemistry covering synthesis, structure and physical properties, chemical properties, metal insertion reactions, formation of heterocycles, carbodiimides in biological and polymer chemistry, and their application in photography, dyeing and related subjects, and analysis. 
     Kurzer et al, &#34;Advances in the Chemistry of Carbodiimides&#34;, Chemical Reviews, Vol. 67, No. 2, pages 107 to 152 (Mar. 27, 1967) reviews carbodiimide chemistry including synthesis, physical properties, structure, chemical properties and various carbodiimide compositions. 
     Wagner et al, &#34;Alpha, Omega-Diisocyanatocarbodiimides, Polycarbodiimides, and Their Derivatives&#34;, Angewandte Chemie (International edition in English), Vol. 20, No. 10, pages 819-898 (October 1981) discusses the synthesis and properties of these carbodiimides and various reactions particularly the in situ production of polycarbodiimides via matrix reactions in flexible polyurethane foams. 
     Khorana, &#34;The Chemistry of Carbodiimides&#34;, Chemical Reviews, Vol. 53, pages 145 to 166 (1953) is a review article covering the preparation and properties of carbodiimides, as well as base catalyzed addition reactions and comparison of carbodiimides with similar systems. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, saturated and ethylenically unsaturated compounds containing carboxylic, amino or alcohol groups are reacted under mild conditions and in short process times with polycarbodiimides containing free isocyanate units to provide polymers with excellent properties. The unsaturated groups bonded to the polymers are particularly important because these groups provide reactive centers that can be crosslinked, either thermally or in the presence of catalysts that initiate polymerization or by radiation. The polymers can also be crosslinked either alone or by copolymerization with various unsaturated monomers. The resulting crosslinked or cured resins provide excellent properties such as hardness, high elongation, excellent toughness, high heat distortion temperatures and good corrosion resistance. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The polymers of this invention, containing isocyanate and carbodiimide, can also be partially branched or crosslinked by reacting the isocyanate groups with the carbodiimide segments, and also by dimerization of the carbodiimide groups. 
     The combination of polycarbodiimides containing free isocyanate groups and their reaction products with carboxylic acids, amines and alcohols can lead to polymers with segments corresponding to the following general formulae: ##STR1## wherein, X represents a hydrogen, chlorine, bromine, an aliphatic, cycloaliphatic, aromatic, or araliphatic radical containing from about 1 to 12 carbon atoms; 
     R represents a difunctional aliphatic, cycloaliphatic, aromatic, or araliphatic radical having from about 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms, and free of any group which can react with isocyanate groups; 
     R 1  represents a hydrogen, an aliphatic, cycloaliphatic, aromatic, araliphatic radical having from about 1 to 12 carbon atoms; 
     R 2  represents a hydrogen or a monovalent radical that can be aliphatic, cycloaliphatic, araliphatic, aromatic, alkyl substituted aromatic, alkyl substituted cycloaliphatic, which can contain one or two double bonds, and which can contain any one or a combination of halogen, phosphorus, silicon, or oxygen groups in any form that does not react with NCO; 
     R 3  represents a divalent radical that can be aliphatic, cycloaliphatic, araliphatic, aromatic, alkyl substituted aromatic, alkyl substituted cycloaliphatic, and can contain any one or a combination of halogen, phosphorus, silicon, or oxygen in any form that does not react with NCO. These groups impart flame retardancy and improve physical and thermal properties. R 3  can be derived from various sources including polyether diols, saturated polyester diols, hydroxy terminated polyurethanes and other hydroxy terminated polymers such as polythioethers, polycarbonates, polyacetals, polybutadiene, polybutadiene copolymers and the like. 
     A represents a divalent group such as: ##STR2## wherein, R 4  is a divalent hydrocarbon radical that can be aliphatic or alicyclic; y is an integer from 1 to 8, preferably from 2 to 5, and most preferably 2 or 3. 
     The aforementioned definitions of R, R 1 , R 2 , R 3 , R 4 , R 5 , X and A are consistent with all subsequent formulations represented herein. 
     The synthesis of these resins can be carried out in the presence or absence of a suitable inert solvent and in general is completed in relatively short times varying from 2 to 10 hours. 
     Suitable inert solvents include hexane, cyclohexane, benzene, toluene, xylene, chlorobenzene, chloroform, methylene chloride, tetrahydrofuran, ethyl acetate, acetone, styrene, alpha-methyl styrene, divinyl benzene, 4-methyl styrene, 4-ethyl styrene, 4-n-butyl styrene, 4-isopropyl styrene, tert-butyl styrene, 4-chlorostyrene, 3,4-dichlorostyrene, methyl methacrylate, methyl acrylate, n-butyl acrylate, n-butyl methacrylate, allyl methacrylate, isopropyl methacrylate, and solvent mixtures. 
     The synthesis can be performed in solution, at low temperatures on the order of about 30° C. to 190° C. and preferably about 50° to 80° C. This is particularly advantageous when using ethylenically unsaturated monomers such as styrene, or methyl methacrylate as solvents or copolymerizable monomers. 
     In one aspect of the invention, these resins can be prepared with pendant and terminal vinyl groups. The first step in preparing resins with terminal vinyl groups is the formation of a polycarbodiimide intermediate with free isocyanate groups starting from a diisocyanate or a mixture of diisocyanates in the presence of a catalyst such as ring or linear pentavalent phosphorus compounds, aluminum alkoxides, arsenic oxides, antimony oxides, sodium alkoxides, naphthenates of Mn, Fe, Co and Cu, and acetyl acetonates of Be, Al, Zn, and Cr, and preferably substituted phospholene oxide or dioxo-oxa-phospholane. Alternatively, ionizing radiation or photochemical initiation, such as ultraviolet light can also be used to effect crosslinking. 
     The diisocyanates which can be used include aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic diisocyanates of the type described, for example, by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, (1949) for example, those corresponding to the following formula: 
     
         OCN--R--NCO                                                (XI) 
    
     wherein, R is as already defined. 
     Suitable diisocyanates include 1,4-tetramethylene diisocyanate; 1,4 and/or 1,6-hexamethylene diisocyanate; 1,12-dodecane diisocyante; cyclobutane-1,3-diisocyanate; cyclohexane-1,3- and 1,4-diisocyanate and mixtures of these isomers; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane; 2,4- and 2,6-hexahydrotolylene diisocyanate and mixtures of these isomers; hexahydro-1,3- and/or 1,4-phenylene diisocyanate; perhydro-2,4&#39;- and/or 4,4&#39;-diphenyl methane diisocyanate; 1,3- and 1,4-phenylene diisocyanate; 2,4- and 2,6-tolylene diisocyanate and mixtures of these isomers; diphenyl methane-2,4&#39;- and/or 4,4&#39;-diisocyanate; naphthalene-1,5-diisocyanate; 1,3- and 1,4-xylylene diisocyanates, 4,4&#39;-methylene-bis(cyclohexyl isocyanate), 4,4&#39;-isopropyl-bis-(cyclohexyl isocyanate), 1,4-cyclohexyl diisocyanate and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI); 1-methyoxy-2,4-phenylene diisocyanate; 1-chloropyhenyl-2,4-diisocyante; p-(1-isocyanatoethyl)-phenyl isocyanate; m-(3-isocyanatobutyl)-phenyl isocyanate, and 4-(2-isocyanate-cyclohexyl-methyl)-phenyl isocyanate, and mixtures thereof. 
     It is also possible in principle to use aliphatic or aromatic diisocyanates of the type which are obtained by reacting excess diisocyanate with difunctional compounds containing hydroxyl or amine groups and which, in practical polyurethane chemistry, are referred to either as &#34;modified isocyanates&#34; or as &#34;isocyanate prepolymers&#34;. 
     In the formation of the polycarbodiimide intermediate, once the polymer has reached a desired molecular weight on the order of about 800 to 40,000 the isocyanate groups and the carbodiimide segments are reacted with saturated or unsaturated monomers having active hydrogens such as carboxylic, amino, alcohol or thio groups. 
     Examples of these materials include acrylic acid, methacrylic acid, acetic acid, phenylacetic acid, phenoxyacetic acid, propionic acid, hydrocynnamic acid, lauric acid, oleic acid, 4-pentynoic acid, propyolic acid, 2-butynoic acid, acrylamide, methacrylamide, phenethyl amine, propargylamine, diethylamine, dipropylamine, piperazine, n-butylamine, propargyl alcohol, 2-phenoxy ethanol, phenethyl alcohol, 2-butyne-1-ol, 3-butyne-1-ol, 2-pentyne-1-ol, 3-pentyne-1-ol, 4-pentyne-1-ol, and hydroxyalkyl acrylates or methacrylates, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, and the like, and mixtures thereof. 
     The saturated or unsaturated monomers can include any one or a combination of halogen, phosphorus or silicon groups. 
     The use of ethylenically unsaturated compounds bonded to the polymer is of particular importance because they provide reactive centers that can be crosslinked. However, the unsaturation can be partially replaced with saturated compounds depending on the desired properties of the resulting resin. Such properties can be tailored in a way that the degree of hardness, elongation, toughness, heat distortion temperatures and corrosion resistance will be dependent on the amount of crosslinking and the percentage of saturated compounds added. This is important for applications such as in bulk molding compounding, sheet molding compounding, resin transfer molding, pultrusion and printed wiring boards. 
     The polycarbodiimide can then be represented as follows: 
     
         OCN--R--N═C═N--R].sub.n NCO                        (XII) 
    
     wherein n=1 to 25, preferably 1 to 15, and wherein R is as previously defined. 
     The polycarbodiimide intermediate is then further reacted with saturated or unsaturated monomers having active hydrogens as already described. This further reaction can be conducted in the presence of an organotin catalyst such as dibutyl tin diacetate, or dibutyl tin di-2-ethylhexoate, dibutyl tin dilaurate, dibutyl tin oxide or tertiary amines, such as triethylamine, tributylamine, triethylanediamine tripropylamine, and the like, to form an acrylic derivative of a carbodiimide which is a copolymerizable thermosetting resin with pendant and terminal vinyl groups and which can be represented by the following structural formulae: ##STR3## wherein n and m independently=0 to 25, preferably 0 to 15, and m+n are always at least 1. ##STR4## wherein, n, m and s independently=0 to 25, preferably 0 to 15 and m+n+s are always at least 1. X, R, R 1 , R 2 , and A, are as already defined. 
     Another aspect of this invention is the preparation of resins with terminal vinyl groups containing urethane and carbodiimide segments along the polymer backbone. The process begins with prepolymers containing isocyanate terminal groups. These isocyanate prepolymers are prepared from diisocyanates or diisocyanate mixtures with any diol or triol ordinarily used as chain extender to make urethanes corresponding to the following general formula: 
     
         R.sub.3 (OH)p 
    
     wherein R 3  is as already defined and p is 2 or 3, which includes polyhydric alcohols having a molecular weight of from about 60 to 250 and also polyester and polyether polyols having a molecular weight of about 150 to 6000, preferably from about 500 to 5000, and most preferably from about 1000 to 4000, of the type known for the preparation of homogeneous and cellular polyurethane plastics. 
     Examples of such compounds include: ethylene glycol, 1,2-and 1,3-propylene glycol; 1,4 and 2,3-butylene glycol; 1,5-pentane diol; 1,6-hexane diol; 1,8 octane diol; neopentyl glycol; 1,4-bis-hydroxymethyl cyclohexane; 2-methyl-1,3-propane diol; glycerol; trimethylol propane; 1,2,6-hexane triol; trimethylol ethane; pentaerythritol; quinitol; mannitol; sorbitol; diethylene glycol; triethylene glycol; tetraethylene glycol; 1,4-butanediol; polyethylene glycols having a molecular weight of up to 400; dipropylene glycol; ethoxylated and propoxylated bisphenol A; polybutylene glycols having a molecular weight of up to 400; methyl glycoside; diethanolamino-N-methyl phosphonic acid ester; castor oil; diethanolamine; N-methyl ethanolamine; and triethanolamine. 
     The diols or triols can also include any one or a combination of halogens, such as chlorine, fluorine, bromine, or iodine; or phosphorus, or silicon groups. 
     The diisocyanates or diisocyanate mixtures are in excess of the diol or trihydric alcohol and react in accordance with the following general equation to form a prepolymer that contains urethane segments and terminal isocyanate groups which can be represented in the following structure: ##STR5## wherein p=2 or 3. 
     The prepolymer that is formed is then further reacted with the excess diisocyanate remaining from the initial reaction step in the presence of a catalyst such as substituted phospholene oxide or dioxo-oxa-phospholane to form a polycarbodiimide having carbodiimide segments and urethane segments with isocyanate terminal groups in accordance with the following structure: ##STR6## wherein q=1 to 40, preferably 1 to 25. 
     The polycarbodiimide is then further reacted with a hydroxyalkyl methacrylate wherein the alkyl is ethyl, propyl or butyl in the presence of an organotin catalyst as above mentioned, to form the resin containing the terminal vinyl groups in accordance with the following structure: ##STR7## wherein, q=1 to 40, preferably 1 to 25. 
     The synthesis of these resins is illustrated by the following examples 1 to 11 which show resins containing pendant and terminal unsaturated groups. Example 12 shows preparation of a resin with only terminal vinyl groups. All parts and percentages are by weight unless otherwise noted. 
    
    
     EXAMPLE 1 
     In a 500 ml three neck flask, 100 grams (0.4498 mole) of isophorone diisocyanate were mixed at room temperature with 0.092 grams (47.87 millimoles) of 3-methyl-1-phenyl-2-phospholene-1-oxide. The temperature was increased to 185° C. and maintained for two hours to form the polycarbodiimide intermediate. Cooling was then applied with a water bath. At 85° C., 80 grams of methyl methacrylate were added, allowing the mixture to cool to 60° C. At this temperature, 25 grams of methacrylic acid were added. Cooling was continued using a water bath to control the exotherm of reaction below 90° C. The temperature was allowed to decrease slowly to 75° C. using a water bath and 71.5 grams (0.4959 mole) of hydroxypropyl methacrylate and two drops (approx. 0.032 grams) of dibutyl tin dilaurate were added. The reaction was continued at 70° C. for 2 hours. 4.0 milligrams of toluhydroquinone (THQ) were added and the mixture was cooled to room temperature. 
     The resulting resin had a light yellow color and was free of NCO or NCN groups as determined by an infrared spectrophotometer model 1310 from Perkin Elmer. Viscosity was measured with a Brookfield viscometer model RVF. Average number and weight number molecular weights were determined by HPLC model 510 from Waters connected to a wisp model 712, a differential difractometer model 410, a Digital computer model 350 and a printer model LA 50. During times were measured by a modified SPI gel test at 180° F. using 1%, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane (USP 245 from Witco). Perkin Elmer DSC-4 differential scanning calorimeter was used to determine the thermal transitions, using heating rates of 20° C./min. The data is summarized in Table 1. 
     This reaction can also be carried out in the presence of an inert solvent. The advantage of using an inert solvent such as styrene or methyl methacrylate, is that the extent of side reactions is reduced, and a greater yield of linear polymer rather than branched polymer is obtained. After preparation of the acrylic derivative of carbodiimide resin is completed, it is already in the presence of unsaturated monomers and is ready to be catalyzed for end use applications. In addition, the reaction in solution can occur at low temperatures on the order of 80° C. 
     EXAMPLE 2 
     In a two liter reactor, 400 grams (1.6 mole) of diphenylmethane diisocyanate (MDI) was dissolved in 320 milliliters of styrene. At 75° C., 0.328 grams (1.707 millimole) of 3-methyl-1-phenyl-2-phospholene-1-oxide catalyst was added. Evolution of CO 2  began immediately. The reaction was continued for two hours at 75° C. 312 grams (2.39 mole) of hydroxyethyl methacrylate (HEMA) was added allowing the mixture to cool to 45° C. Two drops (approx. 0.032 grams) of dibutyl tin dilaurate were added. Cooling was applied with a water bath to control the exotherm at 75° C. to 80° C. At 55° C., 80 grams (0.93 mole) of methacrylic acid was added. The temperature was allowed to rise to 65° C. The reaction was continued at 60° C. for 1 hour. Heat was removed, and 1 part per million (ppm) of Cu naphthenate was added and mixed for 20 minutes. The mixture was then cooled to ambient temperature. 
     The resulting resin had a clear to light yellow color and was free of NCO or NCN groups as determined by infrared spectroscopy by the disappearance of IR bands at 2270 and 2120 cm -1 , corresponding respectively to these groups. Curing behavior for resins of this type is presented in Table 1. 
     EXAMPLES 3-8 
     The procedure of Example 2 was followed with the exception that different ratios of hydroxyethyl or hydroxypropyl methacrylate, methacrylic acid, styrene and methyl methacrylate were used. A mixture of diphenylmethane diisocyanate:toluene diisocyanate in a 50:50 molar ratio was used instead of only diphenylmethane diisocyanate. The results of these experiments are summarized in Table 1. 
     EXAMPLES 9-10 
     The procedure of Example 2 was followed with the exception that different ratios between a mixture of 50:50 molar ratio of diphenylmethane diisocyanate:toluene diisocyanate, and acetic acid instead of methacrylic acid were used. The results of these experiments are summarized in Table 1. 
     EXAMPLE 11 
     The procedure of Example 2 was followed, with the following modifications. A mixture of a 50:50 molar ratio of diphenylmethane diisocyanate:toluene diisocyanate was used in this example. Methacrylic acid was not included in the reaction. Instead, only hydroxyethyl methacrylate was used to react the isocyanate groups and to partially react the carbodiimide segments. The resin had about 15% unreacted carbodiimide segments, as determined by infrared spectroscopy. The results of this experiment are summarized in Table 1. 
     EXAMPLE 12 
     Resins containing carbodiimide segments and ethylenically unsaturated terminal groups are shown in this example. 
     In a three liter reactor 214.4 grams (0.8576 mole) of diphenylmethane diisocyanate (MDI) and 149.35 grams of 2,6 and 2,4-toluene diisocyanate (80:20 mixture, TDI) were dissolved at 45° C. with 500 ml of styrene. To this mixture was added 62.5 grams (0.60 mole) of neopentyl glycol (NPG). The temperature slowly increased to 82° C. due to the exotherm of reaction between the isocyanate and hydroxy groups. The exotherm was allowed to subside and the temperature stabilized at 60° C. At this temperature, two drops of dibutyl tin dilaurate (approximately 0.032 grams) were added and the reaction allowed to exotherm to approximately 65°-70° C. The temperature was set at 75° C. and 0.30 grams (1.56 millimole) of 3-methyl-1-phenyl-2-phospholene-1-oxide was added. Evolution of CO 2  began immediately. The reaction was continued for 3 hours. 230 grams (1.767 mole) of hydroxyethyl methacrylate were added and the temperature was allowed to decrease to 48°-50° C., after which two drops of dibutyl tin dilaurate were added. The exotherm was then controlled between 65° to 70° C. Once the exotherm subsided, the reaction was continued for 30 minutes at 60° C., then, 92.7 milligrams of toluhydroquinone and 0.93 milligrams of Cu naphthenate 6% solution were added. Mixing was continued for 20 more minutes and the mixture was cooled to room temperature. 
     The resin had a clear to light yellow color and contained NCN groups as determined by infrared spectroscopy. Curing behavior for this type of resin is presented in Table 1. 
     Clear castings were prepared by curing the resins with 1% USP 245 (Witco Chemical Co.) at 150° F. for one hour and then post-cured at 250° F. for one more hour. Studies of these castings showed excellent mechanical and physical properties. Some representative results are presented in Table 2 together with properties of commercially available resins for comparison. A general comparison of these properties, showed that the polymers derived from polycarbodiimides can provide materials with higher tensile and flexural strength. In addition, the elongation can be modified according to the amount of crosslinking groups present in the polymer backbone. Table 2 summarizes all important physical properties and characteristics of resins from this invention as well as thermal properties including heat distortion temperature (HDT) and glass transition temperature (Tg). Values for commercial resins have also been included in the upper part of Table 2 for comparison. 
     
                                           TABLE 1__________________________________________________________________________COMPOSITION AND PROPERTIES OF RESINS        EXAMPLES*        1  2   3  4   5   6  7  8  9  10  11  12__________________________________________________________________________DIPHENYLMETHANE        -- 1.60                2.80                  3.43                       3.43                           3.43                              3.43                                 3.43                                    3.43                                       0.86                                          0.86                                               0.86DIISOCYANATE (MDI)2,4 &amp; 2,6-TOLUENE        -- --   2.80                  3.43                       3.43                           3.43                              3.43                                 3.43                                    3.43                                       0.86                                          0.86                                               0.86DIISOCYANATE (TDI)ISOPHORONE    0.45           --  -- --  --  -- -- -- -- --  --  --DIISOCYANATE (IPDI)HYDROXYETHYL -- 2.39                7.53                  7.30                       5.38                           5.38                             -- --  9.99                                       1.50                                          2.11                                               1.77METHACRYLATEHYDROXYPROPYL         0.42           --  -- --  --  --  6.94                                 7.30                                   -- --  --  --METHACRYLATEMETHACRYLIC ACID         0.29           0.93                3.66                  3.02                       2.44                           3.02                              2.56                                 3.02                                   -- --  --  --ACETIC ACID  -- --  -- --  --  -- -- --  0.83                                       0.80                                          --  --NEOPENTYL GLYCOL        -- --  -- --  --  -- -- -- -- --  --   0.60WT. % STYRENE        -- 29.7               31.4                  30.1                      37.5                          34.7                             31.4                                -- 32.8                                      39.2                                          39.9                                              43.6WT. % METHYL 31.1           --  -- --  --  -- -- 29.6                                   -- --  --  --METHACRYLATEVISCOSITY (POISE)         4.00           4.30                2.30                  9.00                      102.0                          13.0                             12.5                                7.2                                   4.6                                      2.7 2.6 6.5Mn           1,050           2,100               1,080                  1,286                      2,056                          1,576                             1,413                                1,369                                   1,605                                      1,260                                          1,300                                              2,600Mw/Mn        1.2           2.2 1.2                  1.5 7.7 2.0                             1.9                                1.9                                   2.8                                      1.5 1.9 3.0180° F. SPI GEL TEST.CATALYST 1% USP-245GEL TIME, MIN.        2.2           --  6.1                  3.2 4.4 3.6                             3.4                                3.3                                   1.9                                      3.2 1.5 2.8GEL TO PEAK, MIN.        1.8           --  3.3                  2.8 3.2 4.2                             4.0                                2.0                                   1.1                                      2.0 1.6 1.2PEAK TIME, MIN.        4.0           --  9.4                  6.0 7.6 7.8                             7.4                                5.3                                   3.0                                      5.2 3.10                                              4.0PEAK EXOTHERM, °C.          180           --  225                  220 2.3 213                             2.5                                191                                   250                                      224 242 239__________________________________________________________________________ *AMOUNTS IN MOLES/GRAM 
    
     
                                           TABLE 2__________________________________________________________________________          PHYSICAL PROPERTIES OF RESINS.          KOPPERS                DION FR                      ATLAC                           VER  VER  ATLAC                                          DION CR                                                ATLAC          3700-25                6695  797  9400 9420 382  6694  570__________________________________________________________________________HDT, °F.           338  277   239   250 266  231  277   302(°C.)   (170) (136) (115)                           (120)                                (130)                                     (110)                                          (136) (150)Tg, °F. *     305   273   298 316  277  340   311(°C.)   *     (152) (134)                           (148)                                (158)                                     (136)                                          (171) (156)FLEX STRENGTH, PSI          10600 14800 11500                           18300                                13400                                     16500                                          10000 20200FLEX MODULUS,  0.57  0.52  0.56 0.52 0.53 0.46 0.48  0.5310.sup.6 PSITENSILE STRENGTH, PSI           5400 7000  7000 10900                                8300 11300                                          6600  10500TENSILE MODULUS,          0.53  0.51  0.52 0.51 0.49 0.46 0.49  0.4910.sup.6 PSITENSILE ELON., %          1.07  1.59  1.48 2.63 1.98 3.6  1.55  2.70TOUGHNESS (FLEX.)          11.52 29.4  13.4 46.6 20.9 44.4 12.1   63(in-lb/in.sup.3)TOUGHNESS (TENSILE)          34.3  64.2  63.2 171.6                                93.9 260.6                                          59.8  164(in-lb/in.sup.3)__________________________________________________________________________                  PHYSICAL PROPERTIES                  OF RESINS.                  ATLAC                       ATLAC                            ATLAC                                 EXAMPLES OF INVENTION                  1041 1070 M-1070                                 3    10   11   12__________________________________________________________________________   HDT, °F.                  293  311  273  250  250  259  273   (°C.)   (145)                       (155)                            (134)                                 (121)                                      (121)                                           (126)                                                (134)   Tg, °F. 302  320  320  295  342  329  302   (°C.)   (150)                       (160)                            (160)                                 (146)                                      (172)                                           (165)                                                (150)   FLEX STRENGTH, PSI                  19100                       17400                            20000                                 22600                                      20000                                           19900                                                22100   FLEX MODULUS,  0.56 0.56 0.49 0.53 0.58 0.53 0.53   10.sup.6 PSI   TENSILE STRENGTH, PSI                  8600 7900 10200                                 9750 8500 10990                                                12500   TENSILE MODULUS,                  0.55 0.56 0.50 0.56 0.59 0.51 0.50   10.sup.6 PSI   TENSILE ELON., %                  1.80 1.60 2.6  2.00 1.62 2.56 3.5   TOUGHNESS (FLEX.)                   49   35  72.8  87  43.5  59  117   (in-lb/in.sup.3)   TOUGHNESS (TENSILE)                   88   68  174.6                                 105   76  167  316   (in-lb/in.sup.3)__________________________________________________________________________ 
    
     Each of the comparative resin products included in the heading of Table 2 and identified by trademark designations were dissolved in styrene and are further identified as follows: 
     Koppers™ 3700-25 (Reichhold Chemicals, Inc.) is a propylene glycol maleate polyester resin. 
     Dion™ FR 6695 (Diamond Alkali Co.) is a brominated bisphenol A-fumarate polyester resin. 
     Atlac™ 797 (Atlas Chemical Industries, Inc.) is a neopentyl glycol-chlorendic polyester resin. 
     VER™ 9400 and VER™ 9420 (Reichhold Chemicals, Inc.) are highly cross-linked vinyl ester resins. 
     Atlac™ 382 (Atlas Chemical Industries, Inc.) is a bisphenol-fumarate polyester resin. 
     Dion™ CR 6694 (Diamond Alkali Co.) is a bisphenol-fumarate polyester resin. 
     Atlac™ 570 (Atlas Chemical Industries, Inc.) is an epoxy novalac vinyl ester resin. 
     Atlac™ 1041, Atlac™ 1070 and Atlac™ M-1070 (Atlas Chemical Industries, Inc.) are acrylic isocyanurate resins.