Abstract:
The invention discloses a fire resistant composite material comprising inorganic particles well dispersed in a polymer having reactive functional groups. The inorganic particles also contain reactive functional groups, originally or after surface modification, that can react with the corresponding reactive functional groups of the polymer to form organic/inorganic composite materials. When the composite material is burned or under fire exposure, the polymer forms a char layer and the inorganic particles radiate absorbed heat. The inorganic particles also strengthen the mechanical properties of the structure through the reaction between inorganic and organic materials, so that the formed char layer is firm and can maintain its structural integrity without peeling off or cracks, effectively preventing direct heat transferring into the interior parts. The fire resistant material is not only flame retardant but also protective toward the interior materials. As a result, the duration of fire resistant ability is tremendously improved.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an organic polymer/inorganic particles composite material showing excellent fire resistant performance under flame sources or fire exposure. Within this composite system, both of the organic polymer and the inorganic particles contain reactive functional groups.  
         [0003]     2. Description of the Related Art  
         [0004]     Fire resistant or fire retardant materials can be used as the architecture or decorative materials. Architecture materials disclosed in TW 583,078 and TW 397,885 primarily comprise a stacked layer, serving as a fire resistant layer, made of nonflammable inorganic materials such as pearlite (or perlite), MgCl 2 , MgO, CaCO 3  or cement. In addition, a stiff fire resistant laminate can be obtained from flexible substrates made of fibers or nonwovens blended with flame retardants, foaming agents and 50˜80? inorganic materials by weight.  
         [0005]     Fire resistant coatings, serving as decorative materials, disclosed in TW 442,549, TW 499,469 and TW 419,514 comprise a combination of foaming and intumescent agents, carbonization agents, flame retardants, and adhesives which foam and intumesce under fire exposure. U.S. Pat. No. 5,723,515 discloses a fire-retardant coating material including a fluid intumescent base material having a foaming agent, a blowing agent, a charring agent, a binding agent, a solvent, and a pigment, increasing resistance to cracking and shrinking. A compound disclosed by U.S. Pat. No. 5,218,027 is manufactured from a composition of a copolymer or terpolymer, a low modulus polymer, and a synthetic hydrocarbon elastomer. The fire retardant additive comprising a group I, group II or group III metal hydroxide with the proviso that at least 1% by weight of the composition is in the form of an organopolysiloxane. U.S. Pat. No. 6,262,161 relates to filled interpolymer compositions of ethylene and/or alpha-olefin/vinyl or vinylidene monomers, showing improved performance under exposure to flame or ignition sources, and fabricated articles thereof. The articles are often in the form of a film, sheet, a multilayered structure, a floor, wall, or ceiling covering, foams, fibers, electrical devices, or wire and cable assemblies.  
         [0006]     Specifically, as shown in  FIGS. 1   a ˜ 1   b , the heated area of a the conventional fire resistant material can be carbonized rapidly and expand to 8˜10 times in volume greater than original due to the foaming, intumescent, and carbonization agents contained. However, as shown in  FIGS. 1   c ˜ 1   d , after long term heating, the intumescent carbonization layer (or the heated part) will slightly crack and peel off, therefore the flame and heat can directly transfer to the interior materials and the fire resistant ability will vanish. Accordingly, an improved fire resistant material is desirable.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     In view of the problems in the related art, the invention utilizes a fire resistant composite material comprising various inorganic particles well dispersed in a polymer having reactive functional groups. The inorganic particles also contain reactive functional groups, originally or after surface modification, so that can react with the corresponding reactive functional groups of the polymer to form organic/inorganic composite materials. Through the reaction between organic and inorganic components, the mechanical and fire resistant properties of the organic polymer are strengthened and enhanced. The organic polymer with reactive functional groups can be polyacid, polyurethane, epoxy, polyolefin, polyamine, polyimide, or derivatives thereof. The reactive functional group can be epoxy group, —COOH, —NH 3 , or —NCO. The preferred inorganic particles comprise hydroxide, nitride, oxide, or metal salt which can react with the functional groups of the organic polymer.  
         [0008]     When the composite material is burned or under fire exposure, the polymer forms a char layer and the inorganic particles radiate the absorbed heat. The inorganic particles also strengthen the mechanical properties of the structure through the reaction between inorganic and organic materials, so that the formed char layer on the surface is firm and can maintain its structural integrity without peeling off or cracks, effectively preventing direct heat transferring into interior parts. The fire resistant material is not only flame retardant but also protective toward the interior materials. As a result, the duration of fire resistant ability is tremendously improved.  
         [0009]      FIG. 3  is a flowchart demonstrating the processes of the organic polymer/inorganic particles composite material. As shown in  FIG. 3 , a detailed description is given in the following embodiments with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
         [0011]      FIGS. 1   a ˜ 1   d  are pictures showing conventional intumescent fire resistant materials subjected to a flame test;  
         [0012]      FIG. 2  is a picture showing an organic polymer/inorganic particles composite material of the invention which is subjected to a flame test;  
         [0013]      FIG. 3  is a flowchart demonstrating the synthesis processes of the organic polymer/inorganic particles composite material; and  
         [0014]      FIG. 4  is a schematic figure demonstrating the flame test for a sample of the organic polymer/inorganic particles composite material.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.  
         [0016]     The organic polymer containing reactive functional groups (such as R—COOH) on main chains is mixed with solvents (such as water, alcohol, or MEK). Subsequently, inorganic particles with corresponding reactive functional groups (such as M-OH) are added to the polymer solution, and the mixture is stirred at 70˜90? for 20 minutes to several hours till the reaction has completed. The slurry of R—COO − M +  is produced by means of the reaction between R—COOH of the polymer and M-OH of the inorganic particles, where R represents carbon chains and M represents metal. A composite sample layer is obtained by coating the slurry on a teflon sheet followed by drying and molding the slurry layer at elevated temperature. The sample layer can be rigid or flexible depending on the organic/inorganic system of the composite. Each sample layer of the following embodiments and comparative examples is prepared according to the processes illustrated in  FIG. 3 . Finally, the sample layer is placed on a piece of A4 size paper and subjected to a flame test. Table 1 shows the results of the flame test in different organic/inorganic systems.  
       First Embodiment  
       [0017]     Poly(ethylene-co-acrylic acid) containing R—COOH was dissolved or dispersed in water. Subsequently, inorganic particles Al(OH) 3  with reactive functional groups M-OH were added to the polymer solution, and the mixture was stirred at 70˜90 for 20 minutes. 1 mm-thick mixture slurry was coated on a teflon sheet, and then placed in an oven, dried at 60? for 60 minutes, 80? for 60 minutes, 100? for 60 minutes, 120? for 30 minutes, 140? for 30 minutes, 160? for 30 minutes, 180? for 30 minutes, and finally, molded at 200? for 240 minutes.  
         [0018]     As shown in  FIG. 4 , the sample layer  20  was removed from the teflon sheet (not shown), and placed on a piece of A4 size paper  10 . A flame test was conducted on the surface of the sample layer  20  by butane gas torch  30  with flame temperature of 1000˜1200? (flame  40 ) for 30 seconds˜3 minutes. The result of the burning phenomenon of the piece of A4 size paper was summarized in table 1. There was no scorch observed on the piece of A4 size paper after heating for 30, 60 and 120 seconds while it became slightly scorched after heating for 180 seconds.  
         [0019]     According to this embodiment, the duration of fire resistant ability was 3 minutes due to the strengthened sample layer, i.e. R—COOH of poly(ethylene-co-acrylic acid) reacted with M-OH of Al(OH) 3  to form chemical bonds instead of physical blending.  
       Second Embodiment  
       [0020]     Poly(ethylene-co-acrylic acid) containing R—COOH was dissolved or dispersed in water. Subsequently, inorganic particles Mg(OH) 2  with reactive functional groups M-OH were added to the polymer solution, and the mixture was stirred at 70˜90 for 20 minutes. 1 mm-thick mixture slurry was coated on a teflon sheet, and then placed in an oven, dried at 60? for 60 minutes, 80? for 60 minutes, 100? for 60 minutes, 120? for 30 minutes, 140? for 30 minutes, 160? for 30 minutes, 180? for 30 minutes, and finally, molded at 200? for 240 minutes.  
         [0021]     As shown in  FIG. 4 , the sample layer  20  was removed from the teflon sheet (not shown), and placed on a piece of A4 size paper  10 . A flame test was conducted on the surface of the sample layer  20  by butane gas torch  30  with flame temperature of 1000˜1200? (flame  40 ) for 30 seconds˜3 minutes. The result of the burning phenomenon of the piece of A4 size paper was summarized in table 1. There was no scorch observed on the piece of A4 size paper after heating for 30, 60 and 120 seconds while it became slightly scorched after heating for 180 seconds.  
         [0022]     According to this embodiment, the duration of fire resistant ability was 3 minutes due to the strengthened sample layer, i.e. R—COOH of poly(ethylene-co-acrylic acid) reacted with M-OH of Mg(OH) 2  to form chemical bonds instead of physical blending.  
       Third Embodiment  
       [0023]     Poly(acrylic acid-co-maleic acid) containing R—COOH was dissolved or dispersed in water. Subsequently, inorganic particles Al(OH) 3  with reactive functional groups M-OH were added to the polymer solution, and the mixture was stirred at 70˜90 for 20 minutes. 1 mm-thick mixture slurry was coated on a teflon sheet, and then placed in an oven, dried at 60? for 60 minutes, 80? for 60 minutes, 100? for 60 minutes, 120? for 30 minutes, 140? for 30 minutes, 160? for 30 minutes, 180? for 30 minutes, and finally, molded at 200? for 240 minutes.  
         [0024]     As shown in  FIG. 4 , the sample layer  20  was removed from the teflon sheet (not shown), and placed on a piece of A4 size paper  10 . A flame test was conducted on the surface of the sample layer  20  by butane gas torch  30  with flame temperature of 1000˜1200? (flame  40 ) for 30 seconds˜3 minutes. The result of the burning phenomenon of the piece of A4 size paper was summarized in table 1. There was no scorch observed on the piece of A4 size paper after heating for 30, 60 and 120 seconds while it became slightly scorched after heating for 180 seconds.  
         [0025]     According to this embodiment, the duration if fire resistant ability was 3 minutes due to the strengthened sample layer, i.e. R—COOH of poly(acrylic acid-co-maleic acid) reacted with M-OH of Al(OH) 3  to form chemical bonds instead of physical blending.  
       Fourth Embodiment  
       [0026]     Polyurethane containing R—NCO was dissolved or dispersed in hexane. Subsequently, inorganic particles Al(OH) 3  with reactive functional groups M-OH were added to the polymer solution, and the mixture was stirred at room temperature for 20 minutes. 1 mm-thick mixture slurry was coated on a teflon sheet, and then placed in an oven, molded at 60? for 120 minutes.  
         [0027]     As shown in  FIG. 4 , the sample layer  20  was removed from the teflon sheet (not shown), and placed on a piece of A4 size paper  10 . A flame test was conducted on the surface of the sample layer  20  by butane gas torch  30  with flame temperature of 1000˜1200? (flame  40 ) for 30 seconds˜3 minutes. The result of the burning phenomenon of the piece of A4 size paper was summarized in table 1. There was no scorch observed on the piece of A4 size paper after heating for 30, 60 and 120 seconds while it became slightly scorched after heating for 180 seconds.  
         [0028]     According to this embodiment, the duration of fire resistant ability was 3 minutes due to the strengthened sample layer, i.e. R—NCO of polyurethane reacted with M-OH of Al(OH) 3  to form chemical bonds instead of physical blending.  
       FIRST COMPARATIVE EXAMPLE  
       [0029]     Poly(ethylene-co-acrylic acid) containing R—COOH was dissolved or dispersed in water. Subsequently, inorganic particles SiO 2  were added to the polymer solution, and the mixture was stirred at 70˜90 for 20 minutes. 1 mm-thick mixture slurry was coated on a teflon sheet, and then placed in an oven, dried at 60? for 60 minutes, 80? for 60 minutes, 100? for 60 minutes, 120? for 30 minutes, 140? for 30 minutes, 160? for 30 minutes, 180? for 30 minutes, and finally, molded at 200? for 240 minutes.  
         [0030]     As shown in  FIG. 4 , the sample layer  20  was removed from the teflon sheet (not shown), and placed on a piece of A4 size paper  10 . A flame test was conducted on the surface of the sample layer  20  by butane gas torch  30  with flame temperature of 1000˜1200? (flame  40 ) for 30 seconds˜3 minutes. The result of the burning phenomenon of the piece of A4 size paper was summarized in table 1. When the flame contacted the surface of the sample layer, the composite rapidly melted within several seconds and then charred irregularly in 30 seconds. The nonuniform char had lost its structural integrity due to the formation of cracks. A piece of A4 size paper became slightly scorched after heating for 30 seconds; scorched after heating for 60 seconds. Finally, the paper substrate burned after heating for 120 seconds because of the majority of cracks.  
         [0031]     According to this comparative example, the duration of fire resistant ability is less than 2 minutes because that R—COOH of poly(ethylene-co-acrylic acid) did not react with SiO 2  to form a well-structured composite by the formation of chemical bonds.  
       SECOND COMPARATIVE EXAMPLE  
       [0032]     Poly(acrylic acid-co-maleic acid) containing R—COOH was dissolved or dispersed in water. Subsequently, inorganic particles Al 2 O 3  were added to the polymer solution, and the mixture was stirred at 70˜90 for 20 minutes. 1 mm-thick mixture slurry was coated on a teflon sheet, and then placed in an oven, dried at 60? for 60 minutes, 80? for 60 minutes, 100? for 60 minutes, 120? for 30 minutes, 140? for 30 minutes, 160? for 30 minutes, 180? for 30 minutes, and finally, molded at 200? for 240 minutes.  
         [0033]     As shown in  FIG. 4 , the sample layer  20  was removed from the teflon sheet (not shown), and placed on a piece of A4 size paper  10 . A flame test was conducted on the surface of the sample layer  20  by butane gas torch  30  with flame temperature of 1000˜1200? (flame  40 ) for 30 seconds˜3 minutes. The result of the burning phenomenon of the piece of A4 size paper was summarized in table 1. When the flame contacted the surface of the sample layer, the composite rapidly melted within several seconds and then charred irregularly in 30 seconds. The nonuniform char had lost its structural integrity due to the formation of cracks. A piece of A4 size paper became slightly scorched after heating for 30 seconds; scorched after heating for 60 seconds. Finally, the paper substrate burned after heating for 120 seconds because of the majority of cracks.  
         [0034]     According to this comparative example, the duration of fire resistant ability is less than 2 minutes because that R—COOH of poly(acrylic acid-co-maleic acid) did not react with Al 2 O 3  to form a well-structured composite by the formation of chemical bonds.  
       THIRD COMPARATIVE EXAMPLE  
       [0035]     Polyurethane containing R—NCO was dissolved or dispersed in hexane. Subsequently, inorganic particles SiO 2  were added to the polymer solution, and the mixture was stirred at room temperature for 20 minutes. 1 mm-thick mixture slurry was coated on a teflon sheet, and then placed in an oven, molded at 60? for 120 minutes.  
         [0036]     As shown in  FIG. 4 , the sample layer  20  was removed from the teflon sheet (not shown), and placed on a piece of A4 size paper  10 . A flame test was conducted on the surface of the sample layer  20  by butane gas torch  30  with flame temperature of 1000˜1200? (flame  40 ) for 30 seconds˜3 minutes. The result of the burning phenomenon of the piece of A4 size paper was summarized in table 1. When the flame contacted the surface of the sample layer, the composite rapidly melted within several seconds and then charred irregularly in 30 seconds. The nonuniform char had lost its structural integrity due to the formation of cracks. A piece of A4 size paper became slightly scorched after heating for 30 to 60 seconds; scorched after heating for 120 seconds. Finally, the paper substrate burned after heating for 180 seconds because of the majority of cracks.  
         [0037]     According to this comparative example, the duration of fire resistant ability is about 2 minutes because that R—NCO of polyurethane did not react with SiO 2  to form a well-structured composite by the formation of chemical bonds.  
       FOURTH COMPARATIVE EXAMPLE  
       [0038]     Poly(vinyl alcohol) containing R—OH was dissolved or dispersed in water. Subsequently, inorganic particles Al(OH) 3  were added to the polymer solution, and the mixture was stirred at 70˜90 for 20 minutes. 1 mm-thick mixture slurry was coated on a teflon sheet, and then placed in an oven, dried at 60? for 60 minutes, 80? for 60 minutes, 100? for 60 minutes, 120? for 30 minutes, 140? for 30 minutes, 160? for 30 minutes, 180? for 30 minutes, and finally, molded at 200? for 240 minutes.  
         [0039]     As shown in  FIG. 4 , the sample layer  20  was removed from the teflon sheet (not shown), and placed on a piece of A4 size paper  10 . A flame test was conducted on the surface of the sample layer  20  by butane gas torch  30  with flame temperature of 1000˜1200? (flame  40 ) for 30 seconds˜3 minutes. The result of the burning phenomenon of the piece of A4 size paper was summarized in table 1. When the flame contacted the surface of the sample layer, the composite rapidly melted within several seconds and then charred irregularly in 30 seconds. The nonuniform char had lost its structural integrity due to the formation of cracks. A piece of A4 size paper became slightly scorched after heating for 30 seconds; scorched after heating for 60 seconds. Finally, the paper substrate burned after heating for 120 seconds because of the majority of cracks.  
         [0040]     According to this comparative example, the duration of fire resistant ability is less than 2 minutes because that R—OH of poly(vinyl alcohol) did not react with the M-OH of Al(OH) 3  to form a well-structured composite by the formation of chemical bonds.  
         [0041]     Due to the chemical bonding between the corresponding reactive functional groups of the organic polymer and the inorganic particles, the formed char layer on the surface is firm with excellent structural integrity and does not easily crack and peel off, effectively preventing direct heat transferring into interior parts. The fire resistant material is not only flame retardant but also protective toward the interior materials. As a result, the duration of fire resistant ability is tremendously improved.  
         [0042]     While the invention has been described by ways of examples and in terms of the preferred embodiments, it can be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.  
                                                       TABLE 1                           Results of the flame test of the organic polymer/inorganic       particles composite materials                    Paper states after direct heating       Organic   Inorganic   at 1000-1200° C. for            polymer   particles   30 secs.   1 min.   2 mins.   3 mins.               poly   Al(OH) 3     unchanged   unchanged   unchanged   Slightly       (ethylene-                   scorched       co-acrylic       acid)       poly   Mg(OH) 2     unchanged   unchanged   unchanged   Slightly       (ethylene-                   scorched       co-acrylic       acid)       poly   SiO 2     Slightly   Scorched   burning   —       (ethylene-       scorched       co-acrylic       acid)       poly   Al(OH) 3     unchanged   unchanged   unchanged   Slightly       (acrylic                   scorched       acid-co-       maleic       acid)       poly   Al 2 O 3     Slightly   Scorched   burning   —       (acrylic       scorched       acid-co-       maleic       acid)       polyure-   Al(OH) 3     unchanged   unchanged   unchanged   Slightly       thane                   scorched       polyure-   SiO 2     Slightly   Slightly   Scorched   burning       thane       scorched   scorched       poly   Al(OH) 3     Slightly   Scorched   burning   —       vinyl       scorched       alcohol