Abstract:
Foamable compositions based on epoxy resins which exhibit good shelf life are obtained through the use of specific blowing agent and curing accelerator systems. The blowing agent system contains azodicarbonamide, while the curative system contains an amine-epoxy adduct such as an imidazole-epoxy adduct. The compositions are capable of providing structural foams which are useful in the manufacture of reinforced structural members and the like.

Description:
The application claims priority from provisional application Serial No. 60/098,110, filed Aug. 27, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention pertains to storage-stable foamable compositions based on epoxy resins. More specifically, specific combinations of blowing agents and curing accelerators are utilized to obtain resins which exhibit improved stability at room temperature over prolonged periods of time, yet can be heated and cured to provide foams capable of strengthening and stiffening hollow metal parts and the like. 
     2. Discussion of the Related Art 
     It is known that a number of industries, e.g., the automobile industry, require parts that are both strong and light-weight. One attempt to achieve this balance between strength and minimal weight provides for hollow metal parts. However, hollow metal parts are easily distorted. Accordingly, it is also known that the presence of structural foam in the cavities of the hollow parts can improve the strength and stiffness of such parts. 
     Generally, such foams comprise a thermosettable resin such as an epoxy resin, a blowing agent and a filler. Preferably, these foams have a density of about 20-40 lb/ft 3  (about 0.30-0.65 g/cc) and are able to withstand heat in excess of 175° C., more preferably in excess of 200° C. Optional ingredients include accelerators, curing, agents, processing aids, stabilizers, colorants, and UV absorbers. 
     Specific formulas for structural foam can vary widely. For example, U.S. Pat. No. 5,575,526 teaches several resin-based structural foams including Formula 2, which contains 54.5% EPON 828 epoxy resin, 7.5% HALOXY 62 epoxy diluent, 6.1% DER 732 flexible epoxy, 2.0% EXPANCEL 551DU blowing agent, 8.8% MICROS microspheres, 17.7% 3M K20 microspheres and 3.4% DI-CY dicyandiamide curing agent. U.S. Pat. No. 5,755,486 discloses thermally expandable resin-based materials containing, for example, epoxy resin, acrylonitrile-butadiene rubber, calcium carbonate, carbon black, fumed silica, glass spheres, curing agent, accelerator, and blowing agent. Modified ureas and blocked boron trichloride complexes are taught to be suitable for use as accelerators. Structural foams such as, e.g., TEROCORE® (a product of Henkel Surface Technologies), are now used in a variety of industries. 
     One recurrent problem with many of the structural foam formulations of this type that have been developed to date, particularly the one part formulations, has been their relatively short shelf-life. 
     Ideally, the components of such formulations once combined together should remain stable and unreacted under the conditions normally encountered during storage and shipment. It would be highly desirable for the properties of the formulations to be unchanged when stored at temperatures at or somewhat above room temperature over a several week or several month period. Unfortunately, certain of the presently available structural foam products tend to partially expand and cure at a temperature of 130° F. (a temperature which storage facilities and transportation means frequently exceed during the summer months or in warm climates) within 24 hours. Merely lowering the amount of curative is not the solution to the problem, since this will typically adversely affect the ability to cure and foam the resin when desired within commercially acceptable temperature and time limits. 
     SUMMARY OF THE INVENTION 
     It has now been surprisingly discovered that the shelf-life problems inherent in previously known structural foam formulations based on epoxy resins may be effectively alleviated through the use of amine-epoxy adduct curatives and an azodicarbonamide blowing agent. Storage-stable foamable compositions thus are provided which are comprised of one or more epoxy resins, one or more blowing agents (at least one of which must be an azodicarbonamide), and one or more curatives (at least one of which must be an amine-epoxy adduct). In one especially advantageous aspect of the invention, the foamable composition is in the form of a pliable dough which additionally contains one or more fillers, particularly hollow glass microspheres. Such compositions when foamed and cured furnish reduced density foams having excellent physical properties, including high strength and stiffness. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Any of the thermosettable resins having an average of more than one (preferably, two or more) epoxy groups per molecule known or referred to in the art may be utilized as the epoxy resin component of the present invention. 
     Epoxy resins are described, for example, in the chapter entitled “Epoxy Resins” in the Second Edition of the  Encyclopedia of Polymer Science and Engineering , Volume 6, pp. 322-382 (1986). Exemplary epoxy resins include polyglycidyl ethers obtained by reacting polyhydric phenols such as bisphenol A, bisphenol F, bisphenol AD, catechol, resorcinol, or polyhydric alcohols such as glycerin and polyethylene glycol with haloepoxides such as epichlorohydrin; glycidylether esters obtained by reacting hydroxycarboxylic acids such as p-hydroxybenzoic acid or beta-hydroxy naphthoic acid with epichlorohydrin or the like; polyglycidyl esters obtained by reacting polycarboxylic acids such as phthalic acid, tetrahydrophthalic acid or terephthalic acid with epichlorohydrin or the like; epoxidated phenolic-novolac resins (sometimes also referred to as polyglycidyl ethers of phenolic novolac compounds); epoxidated polyolefins; glycidylated aminoalcohol compounds and aminophenol compounds, hydantoin diepoxides and urethane-modified epoxy resins. Mixtures of epoxy resins may be used if so desired; for example, mixtures of liquid (at room temperature), semi-solid, and/or solid epoxy resins can be employed. Any of the epoxy resins available from commercial sources are suitable for use in the present invention. Preferably, the epoxy resin has an epoxide equivalent molecular weight of from about 150 to 1000. The use of epoxy resins based on glycidyl ethers of bisphenol A is especially advantageous. The epoxy resin(s) preferably have an average of about 2 epoxy groups per molecule. The epoxy resin or resins should be selected so as to provide the desired combination of properties in both the foamable dough and the final cured foam. 
     Selection of the blowing agent system to be employed is critical to the attainment of a storage-stable foamable composition. Azodicarbonamide (also sometimes referred to as 1,1′-azobisformamide, AZDC, or ADC) must comprise at least part of the blowing agent system. Preferably, the blowing agent system is predominantly (i.e. &gt;50% by weight) azodicarbonamide. Even more preferably, at least 80% by weight of the total amount of the blowing agent system is azodicarbonamide. Blowing agents such as sulfonyl hydrazides may be used as minor components of the blowing agent system. In one embodiment, however, azodicarbonamide is essentially the only blowing agent present in the foamable composition. Azodicarbonamide is available from a number of commercial sources; for example, it is sold under the trademark UNICELL by Dong Jin Chemical of South Korea and under the CELOGEN trademark by Uniroyal Chemical. The particle size of the azodicarbonamide may be adjusted so as to provide the desired foaming characteristics in the foamable composition. For example, it has been found that relatively small particle size azodicarbonamides tend to produce foams having more uniform cell structure than coarser grade azodicarbonamides. “Activated” or “modified” forms of azodicarbonamide may be used to advantage in the present invention. 
     In some formulations, it may be desirable to also utilize a blowing agent activator or accelerator so as to lower the temperature at which release of the gas from the blowing agent takes or to increase the rate at which gas is released at a given cure temperature. Typically, from about 0.1% to about 2% blowing agent accelerator/activator based on the weight of the foamable composition is employed, although the optimum amount will of course vary depending upon the activator/accelerator selected, the amount of blowing agent, cure temperature and other variables. Excess activator/accelerator should not be present in the foamable composition, however, since the storage stability may be undesirably compromised. Suitable blowing agent activators/accelerators include, but are not limited to, ureas (such as the surface-coated oil-treated urea sold by Uniroyal Chemical under the trademark BIK OT), polyols, organic acids, amines, and lead, zinc, tin, calcium and cadmium oxides and salts (including carboxylic acid salts). 
     Also critical in the operation of the present invention is the type of curative system used. Although more than one type of curative may be present, at least one curative must be an amine-epoxy adduct. Amine-epoxy adducts are well-known in the art and are described, for example, in U.S. Pat. Nos. 3,756,984, 4,066,625, 4,268,656, 4,360,649, 4,542,202, 4,546,155, 5,134,239, 5,407,978, 5,543,486, 5,548,058, 5,430,112, 5,464,910, 5,439,977, 5,717,011, 5,733,954, 5,789,498, 5,798,399 and 5,801,218, each of which is incorporated herein by reference in its entirety. Such amine-epoxy adducts are the products of the reaction between one or more amine compounds and one or more epoxy compounds. Carboxylic acid anhydrides, carboxylic acids, phenolic novolac resins, water, metal salts and the like may also be utilized as additional reactants in the preparation of the amine-epoxy adduct or to further modify the adduct once the amine and epoxy have been reacted. Preferably, the adduct is a solid which is insoluble in the epoxy resin component of the present invention at room temperature, but which becomes soluble and functions as an accelerator to increase the cure rate upon heating. While any type of amine could be used (with heterocyclic amines and/or amines containing at least one secondary nitrogen atom being preferred), imidazole compounds are particularly preferred. Illustrative imidazoles include 2-methyl imidazole, 2,4-dimethyl imidazole, 2-ethyl-4-methyl imidazole, 2-phenyl imidazole and the like. Other suitable amines include, but are not limited to, piperazines, piperidines, pyrazoles, purines, and triazoles. Any kind of epoxy compound can be employed as the other starting material for the adduct, including monofunctional, bifunctional, and polyfunctional epoxy compounds such as those described previously with regard to the epoxy resin component. Suitable amine-epoxy adducts are available from commercial sources such as Ajinomoto, Inc., Shell, Pacific Anchor Chemical Company, and the Asahi Chemical Industry Company Limited. The products sold by Ajinomoto under the trademarks AJICURE PN-23 and AJICURE PN-40 and by Air Products under the trademark ANCAMINE 2441 are especially preferred for use in the present invention. 
     The curing of the epoxy resin(s) utilized in the present invention may be additionally assisted by the incorporation of other substances capable of promoting the desired hardening upon heating. Such materials are referred to herein as “curatives”, but also include the materials referred to by workers in the field as curing agents, hardeners, accelerators, activators, and catalysts. While certain curatives promote epoxy resin curing by catalytic action, others participate directly in the reaction of the resin and become incorporated into the thermoset polymeric network which is formed. Although any of the curatives (curing agents) known in the epoxy resin field (see the chapter in the  Encyclopedia of Polymer Science and Engineering  referenced hereinabove) may be used in the present invention in addition to the amine-epoxy adduct, the use of one or more nitrogen-containing compounds such as imidazoles, substituted ureas, amino compounds, amine salts, and quaternary ammonium compounds as the auxiliary curative(s) is desirable (provided that such compounds which cause an unacceptably high degree of epoxy resin reaction under normal storage conditions are avoided). Dicyandiamide (sold commercially by Air Products under the trademark “DICY”) is a particularly preferred auxiliary curative, although other guanidine compounds may also be utilized. In one desirable embodiment of the invention, dicyandiamide (preferably, about 0.5-8 wt. % based on the total weight of the foamable composition) is used in combination with an amine-epoxy adduct (preferably, about 0.1-5 wt. %) in the curative system. The curative system must, however, be selected such that it does not catalyze curing of the foamable composition to any significant extent under typical storage conditions over an extended period. Preferably, the amounts and identities of the components of the curative system are selected such that the foamable composition retains a workable consistency (in one embodiment of the invention, a consistency resembling that of a pliable dough or puffy) for at least two weeks in storage at 130° F. (54° C.) without a significant loss in cured foam properties and does not expand in volume or decrease in specific gravity to an unacceptable extent under such conditions, but foams and cures within about 10 minutes upon being heated at about 150° C. 
     It will be especially desirable to include one or more glass fillers in the foamable composition, as such fillers have been found to impart useful characteristics to the resulting foam (especially where it is to be used to reinforce a structural member). For example, hollow glass microspheres may be added to reduce the density of the foam, and thus the overall weight of the reinforced structural member, while maintaining good stiffness and strength. Commercially available hollow glass microspheres (sometimes also referred to as glass microballoons or microbubbles) include the materials sold by Minnesota Mining and Manufacturing under the trademark SCOTCHLITE, with suitable grades including those sold under the designations B38, C15, K20 and VS 5500. The glass microspheres preferably have diameters in the range of from about 5 to about 200 micrometers (more preferably, less than about 70 micrometers). The crush strength of the hollow glass microspheres may be selected in accordance with the desired characteristics of the cured thermoset foam or reinforced structural member containing said foam. Microsperes having a crush strength in excess of 500 psi are typically employed, however. In a particularly desirable embodiment, hollow glass microspheres comprise from about 5 to about 50 percent by weight of the thermosettable composition. Glass fiber is another preferred type of glass filler, since it helps increase the strength and stiffness of the resulting foam. The glass fiber may be chopped, milled or in other physical forms. 
     Other types of fillers may also be optionally present in the foamable composition. Any of the conventional inorganic or organic fillers known in the thermosettable resin art may be used including, for example, silica (including fumed or pyrogenic silica, which may also function as a thixotropic or rheological control agent), calcium carbonate (including coated and/or precipitated calcium carbonate, which may also act as as thixotropic or rheological control agent, especially when it is in the form of fine particles), fibers other than glass fibers (e.g., wollastonite fibers, carbon fibers, ceramic fibers, aramid fibers), alumina, clays, sand, metals (e.g., aluminum powder), microspheres other than glass microspheres (including thermoplastic resin, ceramic and carbon microspheres, which may be solid or hollow, expanded or expandable), and any of the other organic or inorganic fillers known in the epoxy resin field. Other optional components include diluents (reactive or non-reactive) such as glycidyl ethers, glycidyl esters, acrylics, solvents, and plasticizers, toughening agents and flexibilizers (e.g., aliphatic diepoxides, polyaminoamides, liquid polysulfide polymers, rubbers including liquid nitrile rubbers such as butadiene-acrylonitrile copolymers, which may be functionalized with carboxy groups, amine groups or the like), adhesion promoters (also known as wetting or coupling agents; e.g., silanes, titanates, zirconates), colorants (e.g., dyes and pigments such as carbon black), stabilizers (e.g., antioxidants, UV stabilizers), and the like. 
     The formulations of the present invention preferably contain the above-discussed components in the following amounts (expressed as a percentage of the total weight of the foamable composition). 
     
       
         
               
               
               
             
           
               
                   
               
               
                 Component 
                 Preferred 
                 More Preferred 
               
               
                   
               
             
             
               
                 Epoxy Resin(s) 
                 about 35-85 
                 about 40-70 
               
               
                 Blowing Agent(s) 
                 about 0.1-5 
                 about 0.5-3 
               
               
                 Amine-Epoxy Adduct Curative(s) 
                 about 0.1-5 
                 about 0.25-3 
               
               
                 Other Curative(s) 
                 up to about 10 
                 about 1-8 
               
               
                 Filler(s) 
                 about 5-60 
                 about 20-45 
               
               
                 Adhesion Promoter(s) 
                 up to about 2 
                 about 0.001-0.5 
               
               
                 Colorant(s) 
                 up to about 2 
                 about 0.01-1 
               
               
                 Toughening/Flexibilizing Agent(s) 
                 up to about 15 
                 about 0.5-10 
               
               
                 Blowing Agent Accelerator(s) 
                 up to about 3 
                 about 0.05-2 
               
               
                 Stabilizer(s) 
                 up to about 2 
                 about 0.01-1 
               
               
                   
               
             
          
         
       
     
     Preferably, epoxy resin is present in an amount which is greater than the amount of any of the other components in the foamable composition. 
     The above-described ingredients may simply be combined and mixed to form the foamable composition using any of the conventional processing methods known in the epoxy resin art. 
     The preferred finished product preferably has the consistency of dough for easier handling. The dough may be shaped by extrusion or by hand or other means into any desired configuration. For example, the dough may be conformed to follow the contours of an irregular surface. The dough can then be cured and foamed by heating, preferably at a temperature of at least about 250° F. (about 120° C.), more preferably, at least about 300° F. (about 150° C.). Preferably, it is placed on or near the surface of a solid article comprised of, for example, metal or a thermoset or thermoplastic polymer such that a composite of the structural foam adhered to said surface is created upon foaming and curing. Alternatively, of course, the dough can be placed in a suitable container or vessel for storage until the use of the foamable composition is desired. 
     The foamable compositions of the present invention may be utilized in any end-use application where a relatively light-weight, yet strong, thermoset foam is needed. However, the foamable compositions are especially useful in the production of automobiles and other vehicles to maintain or increase the strength of structural members such as rockers, pillars, radiator support beams, doors, reinforcing beams, and the like. The use of structural foams in such applications is described, for example, in U.S. Pat. Nos. 4,901,500; 4,908,930; 4,751,249; 4,978,562; 4,995,545; 5,124,186; 5,575,526; 5,755,486; 4,923,902; 4,922,596; 4,861,097; 4,732,806; 4,695,343; and 4,610,836 (each of which is incorporated herein by reference in its entirety). 
    
    
     EXAMPLES 
     Examples 1-6 
     Foamable compositions in accordance with the invention were prepared using the following components and varying amounts of two different amine-epoxy adduct curatives: 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Identity 
                 Supplier 
                 Wt., g 
                 phr 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Component 
                   
                   
                   
                   
               
               
                 Epoxy Resin 
                 PEP6134 
                 Peninsula Polymer 
                 561.8 
                 100 
               
               
                 Dicyandiamide 
                 DICY CGNA 
                 Air Products 
                 42.8 
                 7.6 
               
               
                 Azodicarbonamide 
                 CELOGEN AZ120 
                 Uniroyal 
                 19.2 
                 3.4 
               
               
                 Fillers 
               
               
                 Fumed Silica 
                 CAB-O-SIL TS-720 
                 Cabot 
                 3.3 
                 0.6 
               
               
                 Glass Microspheres 
                 SCITCHLIZE 
                 3M 
                 236.6 
                 42.1 
               
               
                   
                 B38/4000 
               
               
                 Calcium Carbonate 
                 WINNOFIL SPT 
                 Zeneca 
                 55.6 
                 9.9 
               
               
                 Wollastonite 
                 NYAD G 
                 Nyco 
                 17.9 
                 3.2 
               
               
                 Other Additives 
               
               
                 Liquid Nitrile Rubber 
                 NIPOL 1312 
                 Zeon 
                 48.3 
                 8.6 
               
               
                 Urea Accelerator 
                 BIK OT 
                 Uniroyal 
                 2.5 
                 0.4 
               
               
                 Carbon Black Colorant 
                 MONARCH 120 
                 Cabot 
                 1.4 
                 0.2 
               
               
                 Silane Adhesion Promoter 
                 A1120 
                 Union Carbide 
                 0.4 
                 0.1 
               
               
                   
               
             
          
         
       
     
     Example 1 used 10.2 g. (1.0 wt.%, 1.8 phr) AJICURE PN-23 amine-epoxy adduct curative (a product of Ajinomoto Company Limited), while Example 2 used the same amount of AJICURE PN-40 amine-epoxy curative (also a product of Ajinomoto Company Limited). In Examples 3-6, the amounts of AJICURE PN-40 were varied as shown in Table 1. Each of the examples exhibited improved storage stability at ambient temperatures, yet foamed and cured when heated to provide a reinforcing foam having good physical properties. 
     
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE I 
               
               
                   
               
               
                 Example 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
             
               
                 Amine-Epoxy 
                 AJICURE 
                 AJICURE 
                 AJICURE 
                 AJICURE 
                 AJICURE 
                 AJICURE 
               
               
                 Adduct 
                 PN-23 
                 PN-40 
                 PN-40 
                 PN-40 
                 PN-40 
                 PN-4- 
               
               
                 Weight (g) 
                 10.2 
                 10.2 
                 8.0 
                 9.0 
                 12.0 
                 14.0 
               
               
                 (%) 
                 1.0 
                 1.0 
                 0.8 
                 0.9 
                 1.2 
                 1.4 
               
               
                 (phr) 
                 1.8 
                 1.8 
                 1.4 
                 1.6 
                 2.1 
                 2.5 
               
               
                 Expansion(%) 
                 63 
                 93 
                 113 
                 120 
                 not run 
                 86 
               
               
                 Compressive 
                 7000 
                 6333 
                 6167 
                 5833 
                 8367 
                 8033 
               
               
                 Strength, psi 
               
               
                 Lap Shear, psi 
                 90 
                 146 
                 64 
                 — 
                 97.6 
                 122 
               
               
                   
               
             
          
         
       
     
     Examples 7-12 
     Examples 1-6 were repeated using higher amounts of the fumed silica and lower amounts of the blowing agent: 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Component 
                 Wt., g 
                 phr 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Epoxy Resin 
                 528.7 
                 100 
               
               
                   
                 Dicyandiamide Curative 
                 40.4 
                 7.6 
               
               
                   
                 Azodicarbonamide Blowing Agent 
                 8.7 
                 1.7 
               
               
                   
                 Fillers 
               
               
                   
                 Fumed Silica 
                 20.2 
                 3.8 
               
               
                   
                 Glass Microspheres 
                 223.3 
                 42.2 
               
               
                   
                 Calcium Carbonate 
                 52.5 
                 9.9 
               
               
                   
                 wollastinite 
                 16.8 
                 3.2 
               
               
                   
                 Other Additives 
               
               
                   
                 Liquid Nitrile Rubber 
                 45.7 
                 8.7 
               
               
                   
                 Urea Accelerator 
                 2.4 
                 0.5 
               
               
                   
                 Carbon Black Colorant 
                 1.4 
                 0.3 
               
               
                   
                 Silane Adhesion Promoter 
                 0.4 
                 0.1 
               
               
                   
                   
               
             
          
         
       
     
     The effects of varying the type and relative amount of amine-epoxy adduct curative used are shown in Table II. 
     
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE II 
               
               
                   
               
               
                 Example 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                   
               
             
             
               
                 Amine-Epoxy 
                 AJICURE 
                 AJICURE 
                 AJICURE 
                 AJICURE 
                 AJICURE 
                 AJICURE 
               
               
                 Adduct 
                 PN-23 
                 PN-40 
                 PN-40 
                 PN-40 
                 PN-40 
                 PN-40 
               
               
                 Weight (g) 
                 12.6 
                 12.6 
                 10.0 
                 8.0 
                 14.0 
                 16.0 
               
               
                 (%) 
                 1.3 
                 1.3 
                 1.1 
                 0.8 
                 1.5 
                 1.7 
               
               
                 (phr) 
                 2.4 
                 2.4 
                 1.9 
                 1.5 
                 2.6 
                 3.0 
               
               
                 Expansion(%) 
                 37 
                 37 
                 46 
                 42 
                 — 
                 45 
               
               
                 Uncured Specific 
                 0.78 
                 0.75 
                 0.75 
                 0.77 
                 — 
                 0.81 
               
               
                 Gravity 
               
               
                 Tensile Strength, 
                 152 
                 149 
                 154 
                 N/A 
                 N/A 
                 118 
               
               
                 psi 
               
               
                   
               
             
          
         
       
     
     Examples 13-18 
     Foamable compositions in accordance with the invention were prepared using the following components and varying amounts and types of other additives: 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Identity 
                 Supplier 
                 Wt., g 
                 phr 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Component 
                   
                   
                   
                   
               
               
                 Epoxy Resin 
                 PEP 6134 
                 Peninsula Polymer 
                 528.7 
                 100 
               
               
                 Dicyandiamide Curative 
                 DICYANEX 200 
                 Air Products 
                 40.4 
                 7.6 
               
               
                 Azodicarbonamide Blowing 
               
               
                 Agent 
                 UNICELL D-200 
                 Dong Jin Chemical 
                 14.0 
                 2.6 
               
               
                 Amine-Epoxy Adduct 
                 AJICURE PN-40 
                 Ajinomoto 
                 10.0 
                 1.9 
               
               
                 Fillers 
               
               
                 Fumed Silica 
                 CAB-O-SIL TS-720 
                 Cabot 
                 20.2 
                 3.8 
               
               
                 Calcium Carbonate 
                 ULTRA-PFLEX 
                 Pfizer 
                 52.5 
                 9.9 
               
               
                 Other Additives 
               
               
                 Liquid Nitrile Rubber 
                 NIPOL 1312 
                 Zeon 
                 45.7 
                 8.7 
               
               
                 Urea Accelerator 
                 BIK OT 
                 Uniroyal 
                 2.4 
                 0.5 
               
               
                 Carbon Black Colorant 
                 MONARCH 280 
                 Cabot 
                 1.4 
                 0.3 
               
               
                   
               
             
          
         
       
     
     Table III shows the results obtained by the use of different fillers and other additives in combination with the above-listed ingredients. 
     
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE III 
               
               
                   
               
               
                 Example 
                 13 
                 14 
                 15 
                 16 
                 17 
                 18 
               
               
                   
               
             
             
               
                 Additional Component 
                 phr 
                 phr 
                 phr 
                 phr 
                 phr 
                 phr 
               
               
                 Scatch L276 
                 42.2 
                 42.2 
                 42.2 
                 42.2 
                 47.3 
                 51.1 
               
               
                 microspheres 1   
               
               
                 KR-55 titanate 2   
                 — 
                 0.6 
                 0.6 
                 0.6 
                 0.6 
                 0.3 
               
               
                 NZ-37 zirconate 3   
                 — 
                 0.4 
                 0.4 
                 0.4 
                 0.4 
                 0.4 
               
               
                 KR-238M titanate 4   
                 — 
                 0.4 
                 0.4 
                 0.4 
                 0.4 
                 0.4 
               
               
                 Z-6020 silane 5   
                 0.1 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                 NYAD G Wollastonite 
                 3.2 
                 3.2 
                 — 
                 — 
                 — 
                 — 
               
               
                 glass fiber 
                 — 
                 — 
                 3.2 
                 6.4 
                 6.4 
                 6.4 
               
               
                 Lap Shear, psi 
                 275 
                 296 
                 288 
                 277 
                 276 
                 249 
               
               
                 Expansion (%) 
                 53 
                 59 
                 64 
                 74 
                 61 
                 42 
               
               
                 Uncured Specific Gravity 
                 0.80 
                 0.79 
                 0.80 
                 0.84 
                 0.76 
                 0.77 
               
               
                 Compressive Strength, psi 
                 10,000 
                 8333 
                 7833 
                 8500 
                 9767 
                 9333 
               
               
                   
               
               
                   1 product of Minnesota Mining &amp; Manufacturing  
               
               
                   2 product of Kenrich Petrochemicals  
               
               
                   3 product of Kenrich Petrochemicals  
               
               
                   4 product of Kenrich Petrochemicals  
               
               
                   5 product of Dow Corning Corporation  
               
               
                   6 product of Nyco  
               
             
          
         
       
     
     Examples 19-25 
     A series of foamable compositions containing the components listed in Table IV was prepared and evaluated for use in the preparation of structural foams as described in the previous examples. The amounts of the listed components are given as a weight percent of the total foamable composition. 
     
       
         
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE IV 
               
               
                   
                   
               
               
                   
                 Identity 
                 Supplier 
                 Ex. 19 
                 Ex. 20 
                 Ex. 21 
                 Ex. 22 
                 Ex. 23 
                 Ex. 24 
                 Ex. 25 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Component 
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Epoxy Resin 
                 PEP 6134 
                 Peninsula Polymer 
                 56.2 
                 54.9 
                 55.3 
                 51.2 
                 52.3 
                 53.6 
                 56.1 
               
               
                 Dicyandiamide Curative 
                 DICY CGNA 
                 Air Products 
                 4.3 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                 DICY 200 
                 Air Products 
                 — 
                 4.2 
                 4.2 
                 3.9 
                 4.0 
                 4.1 
                 43.1 
               
               
                 Azodicarbonamide 
                 CELOGEN AZ120 
                 Uniroyal 
                 1.92 
                 1.45 
                 1.46 
                 1.55 
                 1.58 
                 1.62 
                 1.92 
               
               
                 Blowing Agent 
               
               
                 Amine-Epoxy Adduct 
                 AJICURE PN-23 
                 Ajinomoto 
                 1.02 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                 AJICURE PN-40 
                 Ajinomoto 
                 — 
                 1.04 
                 1.05 
                 1.00 
                 1.00 
                 1.01 
                 1.02 
               
               
                 Fillers 
               
               
                 Fumed silica 
                 CAB-O-SIL TS-720 
                 Cabot 
                 0.33 
                 2.10 
                 2.11 
                 1.96 
                 2.00 
                 2.05 
                 0.33 
               
               
                 Glass microspheres 
                 B38 
                 3M 
                 23.7 
                 23.2 
                 23.4 
                 21.6 
                 22.1 
                 22.65 
                 23.7 
               
               
                 Calcium carbonate 
                 ULTRA-PFLEX 
                 Pfizer 
                 5.6 
                 5.45 
                 5.5 
                 5.1 
                 5.2 
                 5.3 
                 5.6 
               
               
                 Wollastonite 
                 NYAD G 
                 Nyco 
                 1.8 
                 1.8 
                 1.8 
                 — 
                 — 
                 — 
                 1.8 
               
               
                 Glass fiber 
                   
                   
                 — 
                 — 
                 — 
                 7.8 
                 5.9 
                 3.4 
                 — 
               
               
                 Other Additives 
               
               
                 Liquid nitrile rubber 
                 NIPOL 1312 
                 Zeon 
                 4.8 
                 4.8 
                 4.8 
                 4.9 
                 4.9 
                 5.1 
                 4.8 
               
               
                 Urea accelerator 
                 BIK OT 
                 Uniroyal 
                 0.25 
                 0.25 
                 0.25 
                 0.23 
                 0.24 
                 0.25 
                 0.25 
               
               
                 Carbon black colorant 
                 MONARCH 120 
                 Cabot 
                 0.14 
                 0.14 
                 0.14 
                 0.13 
                 0.13 
                 0.14 
                 0.14 
               
               
                 Silane adhesion promotor 
                 A1120 
                 Union Carbide 
                 0.04 
                 — 
                 0.04 
                 — 
                 — 
                 — 
                 0.04 
               
               
                 Titanate 
                 KR 238M 
                 Kenrich Petrochemicals 
                 — 
                 0.21 
                 — 
                 0.19 
                 0.2 
                 0.2 
                 — 
               
               
                 Titanate 
                 KR-55 
                 Kenrich Petrochemicals 
                 — 
                 0.31 
                 — 
                 0.29 
                 0.3 
                 0.3 
                 — 
               
               
                 Zirconate 
                 NZ-37 
                 Kenrich Petrochemicals 
                 — 
                 0.21 
                 — 
                 0.19 
                 0.2 
                 0.2 
                 — 
               
               
                 Expansion % 
                   
                   
                 80 
                 35 
                 44 
                 44 
                 44 
                 44 
                 71 
               
               
                 Lap Shear, psi 
                   
                   
                 157 
                 313 
                 324 
                 318 
                 349 
                 289 
                 142 
               
               
                 Modulus, psi 
                   
                   
                 71.4 
                 90.5 
                 82.0 
                 97.6 
                 92.7 
                 89.1 
                 71.7 
               
               
                 Crush Strength, psi 
                   
                   
                 3639 
                 4306 
                 4986 
                 4882 
                 4515 
                 3930 
                 3503 
               
               
                   
               
             
          
         
       
     
     Examples 26-31 
     Foamable compositions containing the following ingredients, together with varying amounts of glass fiber, were prepared and evaluated for use as structural foams in accordance with the procedures described in the previous examples. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                   
                   
                   
                 Wt., 
                   
               
               
                 Component 
                 Identity 
                 Supplier 
                 g 
                 phr 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Epoxy Resin 
                 PEP 6134 
                 Peninsula 
                 528.7 
                 100 
               
               
                   
                   
                 Polymer 
               
               
                 Dicyandiamide 
                 DICYANEX 200 
                 American 
                 40.4 
                 7.6 
               
               
                 Curative 
                   
                 Cyanamide 
               
               
                 Amine-Epoxy 
                 AJICURE PN-40 
                 Ajinomoto 
                 10.0 
                 1.9 
               
               
                 Adduct 
               
               
                 Azodicarbonamide 
                 UNICELL D-200 
                 Dong Jin 
                 16.0 
                 3.0 
               
               
                 Blowing Agent 
                   
                 Chemical 
               
               
                 Fillers 
               
               
                 Fumed Silica 
                 CAB-O-SILT5720 
                 Cabot 
                 20.2 
                 3.8 
               
               
                 Glass Microspheres 
                 SCOTCNLITE 
                 3M 
                 223.3 
                 42.2 
               
               
                 Calcium Carbonate 
                 ULTRA-PFLEX 
                 Pfizer 
                 52.5 
                 9.9 
               
               
                 Other Additives 
               
               
                 Liquid Nitrile 
                 NIPOL 1312 
                 Zeon 
                 50 
                 9.5 
               
               
                 Rubber 
               
               
                 Urea Accelerator 
                 BIK TO 
                 Uniroyal 
                 2.4 
                 0.5 
               
               
                 Carbon Black 
                 MONARCH 280 
                 Cabot 
                 1.4 
                 0.3 
               
               
                 Colorant 
               
               
                 Titanate 
                 KR-55 
                 Kenrich 
                 3.0 
                 0.6 
               
               
                   
                   
                 Petrochemical 
               
               
                 Zirconate 
                 NZ-37 
                 Kenrich 
                 2.0 
                 0.4 
               
               
                   
                   
                 Petrochemical 
               
               
                 Titanate 
                 KR-238M 
                 Kenrich 
                 2.0 
                 0.4 
               
               
                   
                   
                 Petrochemical 
               
               
                   
               
             
          
         
       
     
     The effect of varying the glass fiber content of such formulations is shown in Table V. 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE V 
               
               
                   
               
               
                 Example 
                 26 
                 27 
                 28 
                 29 
                 30 
                 31 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Glass Fiber 
                   
                   
                   
                   
                   
                   
               
               
                 Weight 
               
               
                 (g) 
                 34.0 
                 40.0 
                 50.0 
                 60.0 
                 70.0 
                 80.0 
               
               
                 (%) 
                 3.4 
                 4.0 
                 5.0 
                 5.9 
                 6.9 
                 7.8 
               
               
                 (phr) 
                 6.4 
                 7.6 
                 9.5 
                 11.3 
                 13.2 
                 15.1 
               
               
                 Lap Shear, 
                 288 
                 321 
                 298 
                 284 
                 293 
                 279 
               
               
                 psi 
               
               
                 Specific 
                 0.78 
                 0.78 
                 0.80 
                 0.82 
                 78 
                 80 
               
               
                 Gravity 
               
               
                 Expansion (%) 
                 59 
                 53 
                 57 
                 62 
                 63 
                 70 
               
               
                   
               
             
          
         
       
     
     While lap shear values were optimized at a glass fiber of about 4 wt. %, maximum expansion was attained at a glass fiber content of about 7.8 wt. %.