US3907063A - Non-flammable paper for speaker cones - Google Patents

Abstract

A non-flammable paper for speaker cones is prepared by adding (1) chlorinated polyolefin having a molecular weight of from 500 to 40,000 and a chlorine content of from 40 to 75 weight percent, or (1)'' bromine-containing chlorinated polyolefin having a molecular weight of from 500 to 40,000, a chlorine content of from 10 to 30 percent by weight and a bromine content of from 60 to 80 percent by weight and (2) antimony trioxide into paper pulp. The paper for speaker cones thereby produced has a good non-flammable property, without losing good sound-reproducing characteristics because it has reduced hygroscopicity and increased metal protecting properties.

Description

limited Statee ?ater1t Nakazawa et al.

[ Sept. 23, 1975 [54] NON-FLAMMABLE PAPER FOR SPEAKER 3,436,494 4/1969 Bozak 181/171 CONES 3,560,441 2/1971 Schwarcz et al 252 81 3,624,028 11 1971 252/81 Inventors: Masahiko Nakalawa; Shizuo 3,738,958 6/1973 Paul 252/81 Nakamura; Mutumi Nakayama, all of Tokyo Japan Primary Examiner stephen J. Tomsky Assignee; Asahi Denka Kogyo K K', Tokyo Attorney, Agent, or FirmWoodhams, Blanchard and Japan Flynn 22] Filed: July 17, 1974 [57] ABSTRACT [21] Appl. No.1 489,156

A non-flammable paper for speaker cones is prepared by adding (1) chlorinated polyolefin having a molecu- [3O] Forelgn Apphcaton Pnonty Data lar weight of from 500 to 40,000 and a chlorine con- July 19, 1973 Japan 48-81162 tent of from 40 to 75 weight percent, or (1) brominecontaining chlorinated polyolefin having a molecular US s 6 weight of from 500 to 40,000, a chlorine content of [51] Int. Cl. .1 610K 13/00; H04R 7/00 from 10 to 30 percent by weight and a bromine con- Field Of Search 52/81; 1 s tent of from 60 to 80 percent by weight and (2) anti- 18l/l70, 6 mony trioxide into paper pulp. The paper for speaker v cones thereby produced has a good non-flammable [56] References Cited property, without losing good sound-reproducing UNITED STATES PATENTS characteristics because it has reduced hygroscopicity 1,759,387 5/1930 BatehOlIS 181/170 and increased metal Protecting Properties- 2,4l6,447 2/1947 Lau hlin et al.. 162/159 3,092,537 6 1963 Bra dts 162/159 9 Clams 2 Drawmg Flgures PQlOlQ I H- AQT US atent Sept. 23.,1975

EXAMPLE 1 COM PAPATIVE EXAMPLE 1 SOUND PPESSURE (ab) I00 Z00 500 I000 2000 500010000 FREQUENCY (CYCLES PER SECOND) i PEIOQ 1 NON-FLAMMABLE PAPER FOR SPEAKER CONES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a loudspeaker having a diaphragm or speaker cone made of a special non-flammale paper. Particularly, this invention relates to a paper for speaker cones having a good non-flammable property and good sound-reproducing characteristics.

This invention also Description of the Prior Art speaker cones which is capable of maintaining its strength for a long period of time because it possesses extremely reduced hygroscopic and increased metal protecting properties.

2. Description of the Prior Art In the past, paper made of cellulosic fibers has been used as the material for making speaker cones because of its advantages such as its relatively low density, high Youngs modulus, high propagation velocity of longitudinal waves, moderate vibration loss, etc.

However, such conventional paper is flammable and therefore speaker cones made of such paper without using additives, such as fireretardants, are insufficient as non-flammable speaker cones now required in the world, especially in the United States.

Furthermore, since paper is hygroscopic and low in metal protecting property, changes of the humidity of the ambient air, etc. cause decreases in strength and deformation of speaker cones, thereby injuring their sound-reproducing characteristics.

In order to minimize or eliminate the above-mentioned disadvantages, much work has been done. For example, fire-retardants such as the following organic phosphorous compounds, halogenated organic compounds and inorganic compounds have been used as additives for imparting to paper a non-flammable property. Such organic phosphorous compounds include tricresyl phosphate, diphenylcresyl phosphate, diphenyloctyl phosphate, trichloroethyl phosphate, tributyl phosphate, triphenyl phosphate, tris(dichloropropyl) phosphate, tris(dibromopropyl) phosphate, chlorophosphonate, bromophosphonate, phosphorus-containing polyols and phosphonitrile chloride. Representative halogenated organic compounds are chlorendic acid, perbrominated polyols, tetrabrominated phthalic anhydride, tetrabrominated bisphenol A, tetrachlorinated phthalic anhydride, decachlorobiphenyl, chlorinated paraffin, polyvinyl chloride, polyvinylidene chloride, etc. Further, representative inorganic compounds are alkali metal or alkali earth metal salts of phosphoric acid and boric acid, etc.

However, the addition of the above-mentioned fireretardants cannot impart a sufficient non-flammable property to paper. Moreover, these fire-retardants are hygroscopic and therefore cause variations of sound reproduction caused by the decrease in strength and the deformation of the speaker cones due to variations in ambient humidity. Similar phenomena are caused by heat applied during processing. Further, above-mentioned halogenated organic compounds are corrosive to metals and therefore cause the corrosion of the parts of speaker cones made from metals due to dehydrohalogenation.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a graph showing the relationship between the frequency and the sound intensity of speaker cones.

2 FIG. 2 is a sectional view of a typical conventional loudspeaker, the cone of which can be made of the special paper in accordance with this invention.

SUMMARY OF THE INVENTION We have discovered a non-flammable speaker cone capable of overcoming the above-mentioned disadvantages.

The speaker cone of this invention has a good nonflammable property; and it possesses good soundreproducing characteristics.

It is an object of this invention to provide a speaker cone having a good fire-retardant property, as well as good sound-reproducing characteristics.

Another object of this invention is to provide a speaker cone capable of maintaining its strength for a long period of time because of its extremely reduced hygroscopicity and increased metal protecting properties.

The physical shape and size of the speaker cone is not critical, according to this invention. The speaker cone can be of any suitable shape and size in accordance with conventional practices in the loudspeaker art for the use of paper speaker cones or diaphragms, and the invention does not pertain to any improvement in such physical features.

In order to make clear the overall construction of a typical loudspeaker, there is illustrated in FIG. 2, a prior art loudspeaker construction (US. Pat. No. 3 436 494) and illustrating the shape of one representative speaker cone. The loudspeaker comprises a housing 2 having a permanently magnetized pole piece 4 and a core 6 with a space for receiving a voice coil 8 of a cone-shaped diaphragm or speaker cone 10. The voice coil 8 has electrically conductive wires 12 wound around the exterior surface thereof. The pole piece 4 and the core 6 provide a magnetic flux in the voice coil aperture 14 and AC electric signals conducted through wires 12 generate a second magnetic flux. The interaction of the two magnetic fluxes induces axial movement of the voice coil to which the speaker cone 10 is attached. Speaker cone 10 is supported by a compliant annulus 13 at the top and bottom.

The speaker cone 10 can be made of the special paper in accordance with this invention.

It will be understood, however, that the invention is not limited to the speaker cone of the shape illustrated in FIG. 2 and that the invention can be incorporated into speaker cones of various shapes and sizes in accordance with the conventional practice in the art of loudspeakers using paper speaker cones and diaphragms.

The speaker cone of this invention is made of cellulosic fiber paper. The paper contains as essential additive constituents uniformly distributed in the cellulosic fibers, (1) chlorinated polyolefin powder or (1) bromine-containing chlorinated polyolefin powder and (2) antimony trioxide.

The preferred examples of chlorinated polyolefins are chlorinated polyethylene, chlorinated polypropylene and chlorinated rubber, wherein rubber means natural or synthetic rubber. Such synthetic rubber includes polyisoprene rubber, polyisobutene rubber, butyl rubber, SB rubber, polybutadiene rubber, neoprene rubber and nitrile rubber, and the most prefera ble is polyisoprene rubber. These chlorinated polyolefin materials such as chlorinated polyethylene, chlorinated polypropylene and chlorinated rubber are conventionally produced as follows.

A starting material of polyethylene, polypropylene or natural or synthetic rubber is dissolved in one or a mix ture of two or more halogenated hydrocarbon solvents and then it it is chlorinated by introducing a gas containing at least 80volume percent of chlorine, and which can contain more than 0.1 volume percent of oxygen and/or ozone, at l7070 C, preferably 4060C, in the presence of mineral acids containing water and radical initiators, whereby to form a reaction mixture containing chlorinated polyolefin having a chlorine content of from 40 to 75 weight percent. The chlorinated polyolefin powder having a molecular weight of 500 to 40,000 and preferably, a particle size of more than 300 mesh and less than 80 mesh, is obtained by steam distillation of the reaction mixture or precipitation in water. If the need arises, pulverization can be carried out after steam distillation or precipitation in order to adjust the particle size of the chlorinated polyolefin powder.

The halogenated hydrocarbon solvents used for dissolving said starting polyolefin must be inert during the chlorination step. Examples of the preferred solvents are halogenated lower aliphatic hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, trichloroethylene and tetrachloroethylene, and halogenated aromatic hydrocarbons such as monochlorobenzene and dichlorobenzene. The most preferred and practical solvent is carbon tetrachloride because of the solubility of the polyolefins therein, the ease of solvent removal after chlorination, and the closeness of its boiling point to that of the reaction temperature.

The amount of polyolefin dissolved in the halogenated hydrocarbon solvent is in the range of l to 20, preferably 3 to 10, percent by weight.

The preferred mineral acids are phosphoric acid, sulfuric acid, hydrochloric acid, etc. The concentration thereof in the aqueous acid solution is usually more than 0.1 N. The amount of aqueous mineral acid solution added to the solution of polyolefin in the halogenated hydrocarbon solvent is from 0.5 to 3.1, preferably l to 2, parts by weight, per one part by weight of polyolefin.

The addition of mineral acid to the chlorination reaction system is not always essential during the initial stage of the chlorination reaction, because the hydrogen chloride gas by-produced during the chlorination becomes dissolved in the water added at the initial stage to form aqueous hydrochloric acid solution. However, the concentration of the mineral acid aqueous solution must be more than 0.1 N during the final stage of the chlorination reaction.

Further, the radical initiators used in this reaction are nitrogen-containing compounds (azo compounds) having the following formula:

R I R" R C N N C R'" l X X wherein R, R, R" and R, which can be the same or different, are alkyls having one to four carbon atoms, and X is CN or C0 R, wherein R' is alkyl having one to four carbon atoms.

Examples of preferred initiators are shown in the following formulas.

4 (fH C|IH CH c| N r: cs

CN CN 3 $3 CH (I N N (I: CH

c0 CH 00 cm The amount of these azo compounds such as azobisisobutyronitrile, added to the reaction system is from 0.01 to 1.0, preferably 0.1 to 0.5, percent by weight, based on the weight of said polyolefin. Furthermore, the chlorine gas used for chlorinating the polyolefins in the halogenated hydrocarbon solvents can be supplied in admixture together with oxygen and/or ozone. Howex er, the gas mixture must contain at least volume percent of chlorine. The oxygen employed can be the oxygen gas industrially produced by air fractionation of gaseous mixtures of oxygen together with inert gases such as nitrogen and carbon dioxide, or air. Ozone, produced industrially for example by corona discharge, can also be used together with the chlorine gas.

The presence of oxygen and/or ozone in the gas remarkably stabilizes the chlorinated polyolefins produced in the co-presence of said mineral acids and azo compounds in the reaction system.

When the oxygen and/or ozone content of the chlorinecontaining gas is less than 0.1 volume percent, the stabilizing effect of oxygen on the chlorinated polyolefin cannot be observed. However, the upper limit of the oxygen and/or ozone content of the chlorine-containing gas is 20 volume percent in order to maintain the chlorine content of the gas high enough to highly chlorinate polyolefins from the economical point of view.

The preferred range of oxygen and/or ozone content is 0.1 to 10 volume percent.

The oxygen can also be supplied in the form of air. Thus, the reaction gas can contain nitrogen as a nonreactive diluent, provided that the chlorine content of the gas is at least 80 volume percent.

In the case of mixing oxygen and/or ozone and/or air into chlorine, either of the following two methods can be adopted. One is to introduce into the reaction system a gas mixture obtained by introducing oxygen and- /or ozone and/or air into the chlorine stream and mixing them uniformly therein. Another method is to introduce the chlorine gas, oxygen and/or ozone and/or air separately and then mix them in the reaction system.

Bromine-containing chlorinated polyolefins are also effective for the purpose of this invention. These brominecontaining chlorinated polyolefins are produced in such a way as disclosed in the Japanese Patent Publication No. 49-8952. The water suspension of the polyolefins listed above is reacted with a brominating agent and chlorine gas to give a bromine-containing chlorinated polyolefins.

The preferred example is a bromine-containing polyolefin having a chlorine content of from 10 to 30 percent by weight and a bromine content of from 60 to 80 percentv In the past, powders of chlorinated polymers have been obtained by either direct pulverization of the solid polymers or the removal of solvent from solvent solutions of the polymers by steam distilling, precipitating or spraying the reaction solution. The powder of chlorinated polyolefins used in this invention is obtained most preferably by removing the solvent from the reac- 6 The amount of chlorinated polyolefins added to the pulp is from 10 to 50, preferably 20 to 40, parts by weight, per 100 parts by weight of fibers. The preferred fixing agents are polyacryl amides, modified epoxy restion solution by means of steam distillation or precipi- 5 ins, starches, polyethylene imines, polyethylene oxides, tation into water. If necessary, pulverization can be carpolyvinyl alcohol, ethylene-vinyl acetate copolymer, ried out after said solvent removal to adjust the particle and carboxymethyl cellulose, the amount of antimony size. Chlorinated polyolefins obtained by steam distillatrioxide added to the pulp is from 5 to 40, preferably 10 tion are macroscopically thin leaf or scale-like powders to 30 parts by weight, per 100 parts by weight of fibers. of low bulk density. 10 Further, the amount of fixing agent added is from 1 to Chlorinated polyolefin powders obtained by precipi- 5, preferably 3 to 5, parts by weight, per 100 parts by tation in non-solvents, for example water, are macroweight of fibers. scopically globular or ellipsoidal powders. These latter The preferred coagulating agents are polyacrylpowders have more uniform particle sizes, compared amide, aluminum sulfate, polyaluminium chloride, with powders obtained by the other methods, and are, polyethylene imine, modified polyamide-epichlorohytherefore, more preferable for use in this invention. drin resin, natural gum and the amount added to the The particle size of chlorinated polyolefins in this inpulp is from 0.01 to 0.1, preferably 0.05 to 0.08, parts vention is preferably more than 300 mesh size and less by weight, per 100 parts by weight of fibers. than 80 mesh size. This invention provides a non-flammable speaker Another essential constituent present in the paper of come capable of maintaining its strength for a long perthe speaker cone, namely, (2) antimony trioxide is also iod of time because of its extremely reduced hygroemployed in the form of a powder of preferably more scopicity and its improved metal protecting property. than 300 mesh size and less than 80 mesh size. The In order to obtain the above-mentioned effects, the speaker cone of this invention is prepared in the'followmolecular weight and the chlorine content of chlori ing way. nated polyolefins must be from 500 to 40,000 and from The preparation of the paper pulp fibers can be car- 40 to 75 weight percent, respectively. When these fearied out in accordance with conventional techniques. tures deviate from the above-stated limited values, the These fibers are beaten with water to form a pulp, also objects ofthis invention cannot be achieved. For examin accordance with conventional papermaking techple, the addition of chlorinated polyolefins having niques. The beaten pulp is thoroughly mixed with dyes, lower molecular weights and chlorine contents than the pigments and paper strengthening agents, and with the above-mentioned ranges does not impart sufficient chlorinated polyolefins and antimony trioxide in a non-flammability to the speaker cones, it causes stickibeater, in the same manner as is conventional for sizing ness of the speaker cones and a decrease of the sizing paper. These additives are precipitated on the fibers by degree. adding a precipitating and fixing agent such as alumi- A preferred example of the preparation of chlorinum sulfate, as is conventional. Further, the use of nated polyolefins, an essential constituent of this invenother additives such as coagulating agents is extremely tion, is as follows: effective. Into a reaction vessel equipped with a stirrer, a chlo- The pulp-water suspension is poured into a porous rine introducing tube, a thermometer and a condenser, mold to form a paper product in the form of a speaker are charged 60 parts (the term parts employed cone. Then, the speaker-cone-type paper product is therein refers to parts by weight) of polyethylene dried to give a speaker cone. In some cases, the speaker (Trademark Sumikathene G 801 melt index 20) and cone can be shaped by compression molding. 1140 parts of carbon tetrachloride. After they are The preferred cellulosic fiber pulps used for the prostirred at reflux temperature for 2-3 hours to dissolve duction of the speaker cone in this invention are said polyethylene, 0.3 part of azobisisobutyronitrile bleached sulfate pulps of soft woods and hard woods (AIBN, 0.5 weight percent, based on polyethylene) is and bleached or non-bleached sulfate pulps of mixtures added and an oxygencontaining chlorine gas is introof soft and hard woods. duced. When 256 parts of chlorine is introduced over a The fiber concentration in the beaten pulp (water period of 7 hours, the reaction is stopped and the reacsuspension of fibers) is from 0.01 to 0.1, preferably tion mixture is steam distilled to give chlorinated poly- 0.03 to 0.07, percent by weight. Further, as paper ethylene powder (CPE-l having a chlorine content strengthening agents there can be used known conven- 69.0 weight percent, a molecular weight of 3,000 and a tional agents, such as starch, natural gum, synthetic particle size of 200 to 220 mesh. CPE-Z, CPP 1 CPP-2, paste, polyacrylamide, ureaformaldehyde resins, epoxy CR-l and CR-2 are produced in a similar way as in the resins, polyethylene imine, polyethylene oxide and mixproduction of CPE1. Their chlorine content, molecutures thereof. The amount of paper strengthening agent lar weight and particle size are shown in Table 1. added to the pulp is from 0.1 to 5 parts by weight, per 100 parts by weight of fibers.

TABLE 1 CPE-l CPE-2 CPP-l CPP-2 CR-l CR-2 chlorinated polyethylene chlorinated polypropylene chlorinated rubber Chlorine content 69.0 45.8 71.0 59.5 68.5 55.3 Molecular weight 3,000 21.000 5,000 12,000 5,000 25.000 Particle size (mesh) 200-220 -100 280-300 -120 -135 85-105 7 The following examples further illustrate this invention. The invention is not limited to the subjects matter of these examples.

EXAMPLES I TO 6 AND COMPARATIVE 8 The pulp-water suspension is poured into a porous speaker cone mold to form a cone-shaped wet paper product. Then, the paper is dried to give a speaker cone.

EXAMPLES 1 O 3 Table 2 shows the amount of each ingredient added and the non-flammability and sound-reproducing char- Speaker cones are produced in the following way. acteristics of the speaker cones produced.

After 100 parts of bleached sulfate fibers of soft As clearly shown in Table 2, speaker cones of this inwood is beaten, the following ingredients are added vention have good non-flammable property and exthereto to make a fiber-water suspension (fiber content tremely low propagation velocity, thereby contributing 0.05 weight percent). good directivity of the sound.

Further, FIG. 1 shows the relationship between the frequency and the sound pressure level of speaker Pans cones in this invention. As clearly shown in FIG. 1, direct black dye 3 speaker cones of this invention have improved sound Paper Strengthcnmg characteristics in the high frequency region and give a (urea-formaldehyde resin) 3 chlorinated polymer", 30 substantially flat sound pressure level in the middle freantimony trioxide quency regi n aluminum sulfate 5 coagulating agent (Trademark Aquoflock) 008 TABLE 2 Addition amount (parts) fibers dye paper fire fixing agent coagulating strengthening retardant agent agent N.B.K,, direct urea- CPE-l/ aluminum Aquoflock (20SR) black fonnaldehyde pans sulfate 305 Example l 100 dye resin SbgOu/ O 5 parts 0.08 parts parts 3 parts 3 parts parts H H H CPEZ H H Example 2 3O/Sb O 20, parts H H H CPRl H H Example 3 3(J/Sb O; 20, parts H H H CPP 2 H H Example 4 3O/Sb O; 20, parts H H H CR4 H H Example 5 3O/Sb O 20, parts H H H CR4 H H Example 6 3O/Sb O 20, parts fiber content weight/area oxygen index propagation frequency in water velocity charactersuspension istics Example 1 0.05% 30 g/m 32 200 m/sec solid line in FIG. 1

Example 2 31 250 Example 3 33 210 Example 4 3] 250 Example 5 32 200 Example 6 30 240 Addition amount (parts) fiber dye paper fire fixing coagulating strengthening retardant agent agent agent N.B.K,, direct ureaphosphoaluminum Aquoflock Comparative (20SR) black formaldehyde nitrile sulfate 305 Example 1 100 dye resin chloride 5 parts 0.08 parts parts 3 parts 3 parts parts Comparative polyvinyl Example 2 chloride 50 parts Comparative none Example 3 fiber content weight/area oxygen index propagation frequency in water velocity character suspension istics Comparative 0.05% 30 g/m 23 900 m/sec dotted line Example 1 in FIG. 1 Comparative 21 950 Example 2 Comparative 18 I000 TABLE 2 Continued Addition amount (parts) fixing agent coagulating agent Example 3 Note: N.B.K,, bleached sulfate pulp of soft wood SR drainage rate The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a loudspeaker of the type which comprises a speaker diaphragm or cone adapted to generate sonic and/or subsonic vibrations in response to an electrical signal, the improvement which comprises: said diaphragm or speaker cone is made of cellulose fiber paper containing uniformly distributed therein l from 10 to 50 parts by weight of particles of chlorinated polyolefin having a molecular weight of from 500 to 40,000 and a chlorine content of from 40 to 75 percent by weight and (2) from 5 and 40 parts by weight of particles of antimony trioxide, the amounts of (l) and (2) each being based on 100 parts by weight of cellulosic fibers, whereby said diaphragm or speaker cone is non-flammable.

2. A loudspeaker as claimed in claim 1, in which the particles of (1) and (2) each having a particle size in the range of from 80 mesh to 300 mesh.

3. A loudspeaker as claimed in claim 2, in which the amount of (l is to 40 parts by weight and the amount of (2) is 10 to parts by weight, each per 100 parts by weight of fibers.

4. A loudspeaker as claimed in claim 1, in which the paper also contains (3) 0.1 to 5 parts by weight of paper strengthening agent, (4) l to 5 parts by weight of fixing agent, and (5) 0.01 to 0.1 part by weight of coagulating agent, each per 100 parts by weight of fibers.

5. A loudspeaker according to claim 1 wherein said chlorinated polyolefin is chlorinated polypropylene.

6. A loudspeaker according to claim 1 wherein said chlorinated polyolefin is chlorinated polyethylene.

7. A loudspeaker according to claim 1 wherein said chlorinated polyolefin is chlorinated natural or synthetic rubber.

8. A loudspeaker according to claim 1 wherein said chlorinated polyolefin is a mixture comprising at least two components selected from the group consisting of chlorinated polyethylene, chlorinated polypropylene and chlorinated natural or synthetic rubber.

9. In a loudspeaker of the type which comprises a speaker diaphragm or cone adapted to generate sonic and/or subsonic vibrations in response to an electrical signal, the improvement which comprises: said diaphragm or speaker cone is made of cellulose fiber paper containing uniformly distributed therein 1) from 10 to 50 parts by weight of particles of bromine containing chlorinated polyolefin having a molecular weight of from 500 to 40,000, a chlorine content of from 10 to 30 percent by weight and a bromine content of from 60 to percent by weight, and (2) from 5 to 40 parts by weight of particles of antimony trioxide, the amounts of (l) and (2) each being based on parts by weight of cellulosic fibers, whereby said diaphragm or speaker cone is nonflammable.

* l l l UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 907 0 3 DATED September 23, 1975 |NV ENTOR(S) Masahiko Nakazawa et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 23; change "5 and 40" to 5 to 40.

Signed ahcl Sealed this twentieth D y of January 1976 [SEAL] Attest.

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner uj'latents and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 907 0 3 DATED September 23, 1975 lN\/ ENTOR(S) Masahiko Nakazawa et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 23; change "5 and 40" to 5 to 40.

Signed ahd Sealed this twentieth D y f Jan ary 1976 [SEAL] Arrest:

RUTH C. MASON Alresn'ng Officer C. MARSHALL DANN Commissioner oj'Patents and Trademarks

Claims (9)

1. IN A LOUDSPEAKER OF THE TYPE WHICH COMPRISES A SPEAKER DIAPHRAGM OR CONE ADAPTED TO GENERATE SONIC AND/OR SUBSONIC VIBRATIONS IN RESPONSE TO AN ELECTRICAL SIGNAL, THE IMPROVEMENT WHICH COMPRISES: SAID DIAPHRAGM OR SPEAKER CONE IS MADE OF CELLULOSE FIBER PAPER CONTAINING UNIFORMLY DISTRIBUTED THEREIN (1) FROM 10 TO 50 PARTS BY WEIGHT OF PARTICLES OF CHLORINATED POLYOLEFIN HAVING A MOLECULAR WEIGHT OF FROM 500 TO 40,000 AND A CHLORINE CONTENT OF FROM 40 TO 75 PERCENT BY WEIGHT AND (2) FROM 5 AND 40 PARTS BY WEIGHT OF PARTICLES OF ANTIMONY TRIOXIDE, THE AMOUNTS OF (1) AND (2) EACH BEING BASED ON 100 PARTS BY WEIGHT OF CELLULOSIC FIBERS, WHEREBY SAID DIAPHRAGM OR SPEAKER CONE IS NON-FLAMMABLE.

2. A loudspeaker as claimed in claim 1, in which the particles of (1) and (2) each having a particle size in the range of from 80 mesh to 300 mesh.

3. A loudspeaker as claimed in claim 2, in which the amount of (1) is 20 to 40 parts by weight and the amount of (2) is 10 to 30 parts by weight, each per 100 parts by weight of fibers.

4. A loudspeaker as claimed in claim 1, in which the paper also contains (3) 0.1 to 5 parts by weight of paper strengthening agent, (4) 1 to 5 parts by weight of fixing agent, and (5) 0.01 to 0.1 part by weight of coagulating agent, each per 100 parts by weight of fibers.

5. A loudspeaker according to claim 1 wherein said chlorinated polyolefin is chlorinated polypropylene.

6. A loudspeaker according to claim 1 wherein said chlorinated polyolefin is chlorinated polyethylene.

7. A loudspeaker according to claim 1 wherein said chlorinated polyolefin is chlorinated natural or synthetic rubber.

8. A loudspeaker according to claim 1 wherein said chlorinated polyolefin is a mixture comprising at least two components selected from the group consisting of chlorinated polyethylene, chlorinated polypropylene and chlorinated natural or synthetic rubber.

9. In a loudspeaker of the type which comprises a speaker diaphragm or cone adapted to generate sonic and/or subsonic vibrations in response to an electrical signal, the improvement which comprises: said diaphragm or speaker cone is made of cellulose fiber paper containing uniformly distributed therein (1) from 10 to 50 parts by weight of particles of bromine containing chlorinated polyolefin having a molecular weight of from 500 to 40,000, a chlorine content of from 10 to 30 percent by weight and a bromine content of from 60 to 80 percent by weight, and (2) from 5 to 40 parts by weiGht of particles of antimony trioxide, the amounts of (1) and (2) each being based on 100 parts by weight of cellulosic fibers, whereby said diaphragm or speaker cone is nonflammable.

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