ASPHALT COMPOSITIONS AND A VIBRATION-DAMPING SHEET FORMED BY THE SAME

Abstract: An asphalt composition comprising (A) 100 parts by weight of straight asphalt; (B) 0.1 to 20 parts by weight of a diene liquid rubber having at least one carboxyl group, epoxy group or amino group in the molecule; and (C) 2 to 350 parts by weight of (i) a fibrous filler or (ii) at least one filler selected from the group consisting of wood flour, talc, calcium carbonate, clay, carbon black and white carbon, having a grain size of 200 microns or less. The composition may also contain (D) 1 to 50 parts by weight of a resinous tackifier. The invention also provides a vibration damping sheet comprising said composition.

Description: ASPHALT COPOSITIONS AND A VIBRATION-DAMPING SHEET FORI4ED BY THE SEE BACKGROUND OF THE INVEN TI ON The present invention relates to an asphalt composition. The present invention also relates to a vibration-damping sheas formed by the asphalt composition. It relates more particularly to an asphalt composition comprising a straight asphalt, a specific liquid rubber, a filler and, if necessary, a resinous tackifier, which has excellent physical properties, particularly heat-resistance, cold-resistance and anti-corrosion characteristics. Heretofore, elastomers have been incorporated into straight asphalt for the modification thereof. These elastomers, however, general have high viscosit es and poor miscibility with asphalt. It is difficult to uniformly disperse such elastomers into asphalt. In the conventional method, liquid rubber having hydroxy groups at the molecule terminals is reacted with straight asphalt by the use of'a cross-linking agent, such as diisocyanate. This method, however, has disadvantages in that diisocyanate has high toxicity and poor stability, and thus inconveniences are involved in handling. In order to prevent vibration of floors of cars and of other substrates, it is effective to heat-bond a vibration-damping sheet formed by molding an asphalt composition, on such substrates. Conventional vibration-damping sheets, however, suffer from the disadvantages of the narrow temperature range in which a satisfactory vibration-preventing effect can be maintained and of their poor quality particularly with regard to reproducibility. SUMMARY OF THE INVENTION It has now been discovered that straight asphalt can be sufficiently modified by incorporating thereinto a specific liquid rubber, a filler and, optionally, a resinous tacificr, without the use of a cross-linking agent. An object of the present invention is to provide an asphalt composition having excellent physical properties, such as heat-resistance, cold-resistance, tackiness, adhesion, weather-resistance, and anticorrosion. Another object of the present invention is to provide an asphalt composition which is suitable for use in the production of an asphalt vibration-damping sheet having improved properties. A further object of the present invention is to provide a vibration-damping sheet formed by said asphalt composition. The present invention, therefore, provides an asphalt composition comprising, (A) 100 parts by weight of an asphalt, preferably a straight as- phalt; (B) 0.1 to 20 parts by weight of a dienetbase liquid rubber containing a carboxyl group, an epoxy group, or an amino group; (CO 2 to 350 parts by weight of a fibrous filler, or at least one filler having a grain size of 260 microns or less and selected from the group consisting of wood flour, talc, calcium carbonate, clay, carbon black and white carbon. The invention also provides a composition comprising: (A), (B), (C) as described above, and ( 1 to 50 parts by weight of a resinous tackifier. The present invention also provides a vibration-damping sheet formed by said composition. DETAILED DESCRIPTION OF TXE INVENTION Component (A) of the present asphalt composition, straight asphalt, is obtained by recovering bitumen present in crude oil by vacuum-distillation or steam-distillation or by a combination thereof. The straight asphalt as used herein usually has a penetration of 10 to 200 and preferably a penetration of 40 to 100.- Although the present invention is intended to improve the physical properties of straight asphalt, the physical properties of blown asphalt can also be improved by the addition of Components (B), (C) and, if necessary, tD) Since straight asphalt generally has inferior physical properties-to blown asphalt, the foregoing objects of the present invention can be attained by using blown asphalt in place of straight asphalt. Thus, the use of such blown asphalt is included within the scope of the present invention. The straight asphalt as used herein may contain about 50X by weight or less of other asphalt components, sudh as natural asphalt, asphaltite, semi-blown asphalt, and blown asphalt-. Component-(B) of the present asphalt composition, liquid libber, is composed mainly of diene monomers. It has a number average molecular weight of 500 to 8,000, and has a viscosity of 2,000 poises or less, preferably 500 poises or less at 300C, thereby exhibiting fluidity at room temperature. It is essential that the liquid rubber have functional groups, such as a carboxyl group, an epoxy group, or an amino group, at the terminals of the molecule, or in the molecule. Liquid rubber having functional groups in the molecule is known in the art. A liquid rubber having a carboxyl group in the molecule is prepared by reacting a liquid rubber having a hydroxyl group in the molecule with maleic anhydride. A liquid rubber having an epoxy group in the molecule is prepared by reacting a liquid rubber having a hydroxyl group in the molecule with a peracetic acid. Those liquid rubbers having a hydroxy group, a cyano group, a mercapto group, a halogen atom, or an aziridino group are somewhat inferior in their heat-stabilization properties when compared to the foregoing liquid rubbers. Example of such liquid rubbers which can be used in the prevent invention include polybutadiene liquid rubbers, such as butadiene homopolymers, e.g., 1,2-polybutadiene and 1,4-polybutadiene, and butaGlene copolymers, e.g., a styrene-butadiene copolymer, an acrylonitrile-- butadiene copolymer, a butadiene-isoprene copolymer, and a butadiene@ pentadiene copolymer, which all contain therein the foregoing func@ tional groups, i.e., a carboxyl group, an epoxy group, or an amiss group In addition, polyisoprene, polychloroprene, etc. containing therein the foregoing function groups can be used. The liqud rubber as used herein acts to increase the heat-stab il- ity of the resulting asphalt composition The amount of the liquid rubber added is from 0.1 to 20 parts by weight, preferably from 0.5 to 10 parts by weight, per 100 parts by weightqof the asphalt, Com- ponent (A) of the present asphalt composition. When the amount of the liquid rubber is less than 0.1 parts by weight, the heat-stabilization effect is small, and when the amount thereof is greater than 20 parts by weight, the softening point of the asphalt composition is undesir- ably lowered Component (C) of the present asphalt composition, the filler, reacts chemically with the functional groups of the liquid rubber tb some extent to form a weak bond, thereby curing the liquid rubber, increasing the softening point of the asphalt composition, and im-- proving the heat-stability of the asphalt composition. The filler used in this invention includes a fibrous filler such as asbestos, and/or at least one filler -selected from the group con sisting of wood flour, talc, calcium carbonate, clay, carbon black, and white carbon which have a grain size of 200 microns or less. Of these fillers, wood flour, talc, and calcium carbonate are partial larly preferred. ExampLes of such fibrous fillers include asbestos, insoluble anhydrous gypsum crystal fiber or its modified product, and a fiber opening-processed product of waste paper or its modified product. Of these fibrous fillers, asbestos is particularly preferred. It is to be noted that the physical properties of such an asphalt composition cannot be improved by adding sand, gravel, etc. thereto. The grain size of the filler is generally preferred to be as small as possible although it varies depending on the type of the filler. It is usually 200 microns or less, preferably 150 microns or less, and more preferably 100 microns or less. When the filler has a grain size of more than 200 microns, its reactivity is- lowered because of its reduced specific surface area, and thus it cannot sufficiently contriD- ute to the improvement in the physical properties of the composition. In greater detail, it is preferred that wood flour has a grain size of 150 microns or less (passing through 100 mesh screen), talc has a grain size of 50 microns or less, and calcium carbonate has a grain size of 2 microns or less. Fibrous fillers such as asbestos and a fiber opening-processed product of aste paper can be used irrespective of their length, because they have large specific surface areas. The amount of the filler added is from 2 to 350 parts by weight, preferably from 5 to 200 parts by weight, per 100 parts by weight of the asphalt, Component (A) of the asphalt composition. When the amount of the filler added is less than 2 parts by weight, an increase in the softening point of the asphalt composition is small, and when it is more than 350 parts by weight, a uniform dispersion of the filler in the composition cannot be attained. When molding the vibration-damping sheet from the present asphalt composition, the filler acts in combination with the liquid rubber, thereby increasing the softening point of the vibration-damping sheet and controlling the heat fluidity of the sheet to an appropriate range. This improvement in the heat fluidity permits bringing the sheet into close contact with an uneven substrate without changing the uniform thickness thereof. The composite action of the liquid rubber and the filler, 4,e., Components (B) and (C) of the present asphalt composition, can be obtained more effectively by mixing them in advance than by mixing them directly with the other components. The asphalt composition of the present invention comprising Components (A),. (B) and (C) as described hereinbefore has s greatly increased softening point, markedly improved heat stability, without a lowering of the rust-prevention ability of the straight asphalt. At. the same time, the asphalt composition of the present invention has improved cold-resistance, stickness, adhesion, weather resistance, etc., as- compared with conventional straight asphalt compositions. Further more, the asphalt composition of the present invention has the advantage that since the Components (A), (B), and (C) are not toxic and have- high stability, they can be mixed or handled with ease in the pro duction of the asphalt composition. In another embodiment of the present invention, the asphalt composition of the present invention comprises (A), (B) and (C) as described hereinbefore and 1 to 50 parts by weight of Component (D), resinous tackifier. Examples of such resinous tackifiers which can be used include a natural resin, such as rosin and dammer; a modified rosin, such as polymerized rosin and partially hydrolized rosin; derivatives of rosin or modified rosin, such as glycerol ester rosin and pentaerythritol ester rosin; a polyterpene resin, such as a ss-pinene polymer; a modified terpene product, such as terpene phenol; an aliphatic hydrocarbon resin, such as an olefinic polymer, and its modified product; a cyclopentadiene resin; an aromatic petroleum resin; a phenol resin and an alkylphenol-acetylene resin; a styrene resin; a xylene resin; a cuma- rone-indene resin; and a vinyl toluene-a-methyl-styrene- copolymer. These tackifiers can be used alone or in combination with each other. Of these tackifiers, those having a softening point of about from 70 to about 1500C are preferably used In particular, it is preferred to use petroleum resins or to use such petroleum resins in combination with other resins. The amount of the resinous tackifier added is within the range of from. 1 to 50 parts by weight per 1.00 parts by weight of the straight asphalt. When the amount of the resinous tackifier added is less than 1 part by weight, the stiffness required for the vibration-damping sheet, which is to be molded from the asphalt compositiDn of the present invention3 is insufficient, and when the amount is greater than 50 parts by weight, the elasticity of-the vibration-damping sheet is adversely affected and thus its vibration-preventing properties are deteriorated. The asphalt vibration-damping sheet can be obtained by molding the asphalt composition of the present invention in a sheet-like form. In particular, a preferred sheet can be obtained from an asphalt corn- position having the following formulation: (A) 100 parts by weight of straight asphalt; (B) about 1 to about 50 parts by weight of the resinous tackifier; and a mixture of about 0.1 to about 10 parts by weight of the diene-based liquid rubber; and (c) about 100 to about 300 parts by weight of the filler. In accordance with the foregoing formulation, the diene-base liquid rubber (Component (B) ) and the filler (Component (C) ) act in combination with each other, and the resulting composite action increases the softening point of the vibration-damping sheet to a suitable level and controls the heat fluidity (attachment to substrates) of the sheet within the range that is suitable for use as a vibrationdamping material. It is preferred to bring Component (B) in direct contact with Component (C) or to mix Components (B) and (C) in such a manner that they frequently come in contact with each other. For example, in accordance with one embodiment, Components (A) and (3) are not brought in contact with each other in advance, and Components (A), (B), (C) and CD) are separately heated to about 100 to 2000C and then mixed at the same time. It is more preferred to prepare a mixture of Components (B) and (C); Component (A) and Component (D) are mixed in any desired order or mixed at the same time. - It is preferred to admix a mixture of Components (B) and (C) and a mixture of Components (A) and (D). In particular, those embodiments wherein a mixture of Components (B) and (C) is utilized are preferred. In mixing these components, it is preferred that Component (A) or a mixture of Components (A) and (D) is heated to the range of about from iOO to 2000C as describe$ above,. When the temperature of Component (A) or the mixture of Components (A) and (D) is lower than 1000 C, undesired difficulties are involved, often leading to insufficient mixing. On the other hand, when the temperature is higher than 200 cm, thre may be deterioration in the quality of Component (3). The production of an asphalt vibration-damping sheet from the asphalt composition of the present invention will be explained in detail. Component (A) (straight asphalt) is placed in a pot and heated to about from ]60 to 1700C, and,Component (D) (tackifier) was added thereto The resulting mixture is further heated with stirring to form a molten mixture of Components (A) and (D). The thus-obtained molten mixture is introduced into, for example, a heat-insulation type kneader. An example of such heat-insulation type kneaders is a kneader provided with a ribbon feeder wherein kneading and feeding of a kneaded product can be performed at the same time in a cylindrical kneading zone equipped with a heat-insulation means. A material to be kneaded is introduced therein to through one end of the kneading zone, successively moved to the other end while being heated and kneaded, and then is discharged. Along the heat-insulation type kneader between the inlet for the introduction of the material to be kneaded to the outlet through which the kneaded material is discharged, an inlet for introduction of Component (B) and an inlet for introduction of Component (C) are provided in any desired order. An inlet for introduction of the molten mixture of Components (k) and (D) is provided. Thus, a mixture of Components (A), (B), (C) and (D) is obtained, which is then formed in a sheet-like form having-a desired thickness. Alternatively, Components (B) and (C) may be kneaded in advance by the use of a suit- able- kneader and introduced in the form of a molten mixture through the same introduction inlet. The molding of the molten mixture in the sheet-like form can be performed by utilizing, for example, a calender roll. Thereafter, if desired, the thus-obtained sheet-like molding is subjected to usual working, for example, is cut to a desired form or bored by the use of a press or cutter. In accordance with the foregoing method, a vibration-damping sheet having good vibration-preventing properties over a wide temper ature range and having excellent cold-resistance can be produced in high yield- even when there is slight variation in the ratio of the straight asphalt to the fibrous filler. The asphalt compositions of the present invention, comprising Components (A), (B), and (C), and comprising Components (A), (B), (C) and (D) can be widely used as a coating material, an asphalt paint, or the like. In particular, they can be suitably used in production of an asphalt vibration-damping sheet. EXAMPLES This invention will be explained in greater detail by reference to the following examples and comparative examples. Examples 1 to 18 To a straight asphalt having a penetration m from 60 to 80 was added a predetermined liquid rubber end an asbestos having a fiber length of 1 millimeter Qr less, or a filler having a predeter@ mined grain size, in predetermined amount and the resulting mixture was uniformly kneaded to obtain an asphalt composition. The softening point of the thus-obtained asphalt composition is shown in'. Table 1, The softening point was measured in accordance with JIS K2531. petroleum asphalt softening point testing method (ring and bail method) (in glycerol bath) The "penetration" value form the. asphalt is measured in accordance with JIS K2530 (Penetration Standard) Table 1 Straight Filler Asphalt Liquid Rubber Softening Example Amount Point No. (parts by (parts by Type Grain Size (parts by weight) weight) (microns) weight) ( C.) 1 100 8 *1 wood flour less than 74*5 50 more than 175 2 " 4.5*1 " " 50 165.0 3 " 8 *1 asbestos less than 1 millimeter*6 32 153.0 4 " 3.6*1, " 32 127.0 5 " 8 *1 talc 10.0 160 165.0 6 " 7.3*1 " " 140 110.0 7 " 8 *1 calcium carbonate 0.04 100 123.0 8 " 6 *1 " " 100 110.0 9 " 8 *2 wood flour less than 74*5 50 163.0 10 " 4.5*2 " " 50 142.0 11 " 8 *2 asbestos less than l millimeter*6 32 145.0 12 " 3.6*2 " " 32 123.0 13 " 8 *2 talc 10.0 160 130.0 14 " 7.3*2 " " 140 107.0 15 " 8 *2 calcium carbonate 0.04 100 117.0 16 " 6 *2 " " 100 101.0 17 " 8 *3 talc 10.0 160 144.5 18 " 8 *4 " " 160 155.5 *1): Butadiene homopolymer having carboxyl group at the terminal, number average molecular weight: 2,800 Viscosity: 150. poises (300 C) *2): Butadiene homopolymer having epoxy group in the molecular, number average molecular weight: 2,800 Viscosity: 200 poises (250C) *3): Butadiena-acrylonitrile copolymer having amino group at the terminal, number average molecular weight: 3,400 Viscosity: 1,900 poises (300C) *4): Butadiene-acrylonitrile copolymer having carboxyl group at the terminal, number average molecular weight:. 3,400 Viscosity: 1,200 poises (30 C) Passing through 200 mesh screen *6): Fiber length Comparative Examples 1 to 19 The procedure of Example l was repeated using a straight asphalt having a degree of penetration of 60 to 80. The results are shown in Table 2. Example 19 The procedure of Example 13 was repeated using a straight asphalt (softening point, 46.0 C). The thus-obtained asphalt composition had a softening point of l25.0 C. Table 2 Compar- Straight ative Asphalt Liquid Rubber Filler Sofening Example Amount Point No. (parts by (parts by Type Grain Size (parts by weight) weight) microns) weight ( C.) 1 100 - - - - 50.0 2 " 8 *1 - - - 44.0 3 " " *2 - - - 48.0 4 " " *3 - - - 47.0 5 " " *4 - - - 47.0 6 " - wood flour less than 74*5 50 117.0 7 " - asbestos less than 1 millimeter*6 32 76.5 8 " - talc 10.0 160 97.5 9 " - calcium carbonate 0.04 100 81.0 10 " 2.5*1 talc 10.0 160 83.0 11 " 2.5*2 " " 160 85.0 12 " 8 *1 " " 400 - *9 13 " " " " 400 - *9 14 " 8 *2 " " 400 - *9 15 " " " " 400 - *9 16 " 8 *7 - - - 40.0 17 " " talc 10.0 160 63.0 18 " 8 *8 - - - 49.5 19 " " talc 10.0 160 92.0 *1)-*6): the same meaning as described for Table 1. *7): Butadiene homopolymer having hydroxy group at the terminal, number average molecular weight: 2,800 Viscosity: 50 poises (300C) *8): Kaliflex TR-1l02: Styrene-butadiene-styrene block terpolymer *9): Measurement was impossible because no uniform dispersion could be attained. Hereinafter, a method of molding a vibration-damping sheet from the asphalt composition of the present invention will be explained. Vibration-preventing properties, cold impact resistance, sur face stickness, heat fluidity and apply suitability were evaluated or tested as follows: 1 Vibration-preventing Properties Vibration-preventing properties are evaluated by the resonance method (as described in page 438 of Souon Taisaku handbook (Handbook for noise prevention), published by Japan Sound Material Association in 1966). A vibration-damping sheet 2 millimeters thick is placed on a steel plate (0.8 x 20 x 200 mm), baked at 150 + 20C for 30 minutes, and allowed to cool. Thereafter, sheet portions protruding from the steel plate were cut off with a knife to provide a test specimen. In accord ance with the foregoing resonance method, the resonance frequency and half width are measured at 2O0C, 40"C, 60"C and 80"C, and a loss co efficiency n at each temperature is calculated. Greater values of the loss coefficiency 9 indicate higher vibra tion-preventing properties. Wnen the loss coefficient is less than 0.05, no practical vibration-preventing effect can be obtained (i.e., the practical lower limit is 0.05). 2. Cold Impact Resistance A vibration-damping sheet (90 x 150 millimeter) is placed on a coated steel plate (200 x 150 x 1 millimeter), bonded thereto by heating 150 + 2"C for 30 minutes, and then allowed to cool down to room temperature to provide a test specimen. On two trigonal prism-like supports which are placed in parallel with each other with a distance of 180 millimeters therebetween is mounted the vibration-damping sheetbonded steel plate in such a manner that the vibrationing sheet surface faces downward, and it is held in that state at -20 + 20 for 30 minutes. Thereafter, a 50 grams steel ball is dropped on the test specimen at the central portion thereof and the height (centimeter) at which cracking and peeling begin to occur is measured. Great-er values of the height indicate higher cold impact resistance. 3. Surface Stickness A vibration-damping sheet (about 80 millimeters square) is placed on a coated steel plate (100 x 100 x 1 millimeter), bonded thereto by heating at 150 t 20C'for 30 minutes, and then allowed to cool down to room temperature to provide a test specimen. On the thus-obtained test specimen are placed two sheets. of 70 millimeters square gauze and furthermore a 500 grams weight having a bottom of 40 millimeters in diameter in that sequence. After they are heated at 1000C for 2 hours and then allowed to cool down to room temperature, the weight is removed and then the gauzes are removed. The state in which the gauze sticks and is. stained is examined. Evaluation of stickness and stain: O negative X positive 4. Heat Fluidity On a coated steel plate (200 x 200 x 1 millimeter) with a bore (60 millimeters in diameter) in the center thereof is mounted a vibration-damping sheet (150 x 150 millimeter) at the central portion thereof to provide a test specimen. The test specimen is placed horizontally at a location of 15 centimeters from the floor in a forced air ventillation type drier maintained at 150 + 2 C. After the test specimen is heated at that temperature for 30 minutes. The depth (millimeter) to which the sheet sags through the bore, and the sags or runs are examined. Evaluation: EMI16.1 Sagging 10 m/m or less, no runaway Sagging 15 m/m or more, no runaway (Runaway), coming off the sagged part Sagging 10 m/m or less, (insufficient sagging) 5. Apply Suitability (Suitability of Application) A vibration-damping sheet is cut to 30 millimeters (width) x 300 millimeters (length) to provide a test specimen. The test specimen is placed on a base having a 45" slant at the front thereof and having a smooth surface, and it is pushed toward the slant slowly (at a rate such that the top of the test specimen reaches the slant surface in about 8 seconds). When the. top of the test specimen sags and reaches the slant surface, a location at which the other end of the test specimen is positioned is measured with a scale. Thus, the distance (centimeter) for which the test specimen is pushed is determined. When the distance is too small, the stiffness of the vibrationdamping sheet is poor and problems occur in applying it in the summer season. On the other hand, when the distance is too large, the vibration-damping sheet is tpo hard and similarly, problems occur in applying it in the winter season. Evaluation: EMI16.2 Too soft: 11 centimeters or less 11 centimeters to 13 centimeters 13 centimeters to 16 centimeters 16 centimeters to 18 centimeters Too hard: 18 centimeters- or more Examples 20 to 26 To 100 parts by weight of a straight asphalt (60 to 80) was added 10 parts by weight of a petroleum resin (Nisseki Neopolymer, softening point: 1200C), and the resulting mixture was then melted by heating at 17000 to obtain an asphalt mixture. A liquid rubber (1 part by weight) was heated to 500 and dropwise added to and dispersed in an asbestos 7T-5/filler mixture having the formulation shown in Table 3. The thus-obtained dispersion and the above-obtained asphalt mixture were kneaded in a heating or heat-insulation type knead-extruder (Step A indicated in the footnotes of Table 3) and extruded onto an endless belt rotating at a constant speed. The thus-extruded material was rolled into a sheet of 2 millimeters thick by the use of calender rolls while cooling, e.g., by air circulation or water spraying, to obtain the vibration-damping sheet of the present invention. The formulation of each example and the results are shown in Table. 3. Comparative Examples 20 to 22 In accordance with the formulation and mixing order indicated in Table 3, a' vibration-damping sheet was produced using a straight asphalt (60 to 80). The results are shown in Table 3. Table 3 Comparative Example Example Example 20 21 22 20 21 22 23 24 25 26 Straight Asphalt 100 100 100 110 110 110 100 100 100 100 Asphalt (60 to 80) Mix@ure Petroleum Resin 10 10 10 10 10 10 10 Binder Component Composition Liquid Rubber A 1 1 1 1 1 Modifier B 1 (parts by C 1 weight) Fibrous Asbestos 7T-5 12 17 22 12 17 22 17 17 17 Filler Ground waste paper 20 Filler Component Talc 210 200 185 210 200 185 200 200 200 Filler Calcium Carbonate 200 Binder/Fibrous Filler 9.3 6.5 5.0 9.3 6.5 5.0 5.5 6.5 6.5 6.5 Production Steps (mixing order) (I) (I) (I) (II) (II) (II) (I) (I) (I) (I) Yield (%) 95 95 95 14 65 18 94 96 95 97 Performance Vibration-preventing Temperature 20 C 0.13 0.14 0.14 0.08 0.07 0.08 0.12 0.14 0.14 0.13 Properties 40 C 0.12 0.14 0.15 0.07 0.06 0.06 0.10 0.12 0.12 0.11 Cold Impact Resistance (centimeter) 65 75 80 30 35 40 60 60 50 60 Surface Stickness O O O X X X O O O O Heat Fluidity @ @ @ X O @ @ @ @ @ Apply Suitability @ @ @ X X @ @ @ @ @ Note: Liquid Rubber A: Butadiene homopolymer having carboxyl group at the terminal *1 Liquid Rubber B; Butadiene homopolymer having epoxy group in the molecule *2 Liquid Rubber C: butadiene-acrylonitrile copolymer having carboxyl group at the terminal *3 Production Step I: A filler in which a liquid rubber is pre viously dispersed, and an asphalt mixture are mixed. Production Step II: A filler and an asphalt are mixed. *1): Butadiene homopolymer having carboxyl group at the terminal, number average molecular weight: 2,800 Viscosity: 150 poises (300C) *2): Butadiene homopolymer having epoxy group in the molecule, number average molecular weight: 2,800 Viscosity: 200 poises (25"C) *3): Butadiene-acrylonitrile copolymer having carbqxyl group at the terminal, number average molecular weight: 3,400 Viscosity:- 1,200 poises (300C) In the vibration-damping sheet produced from the asphalt composition of the present invention, the vibration-preventing properties are markedly increased over a wide temperature range by the composite action of the resinous tackifier and the liquid rubber even though the amount of the liquid rubber added is significantly small, and furthermore it has improved cold impact resistance and surface stickness characteristics. Additionally, in the vibration-damping sheet of the present invention, the heat fluidity is not lowered even if the ratio of binder to fibrous filler is changed, and thus a large volume of sheets can be produced while maintaining high quality, whereas in the conventional product wherein no liquid rubber is added, the heat fluidity is abruptly' lowered by a change in the ratio of binder to fibrous filler, and as a result, the quality of product is poor and the yield is lowered greatly. Furthermore, the vibration-damping sheet is excellent in the so-called stiffness, and even if its surface area is large, it can be easily mounted on a plate member. Thus, it is excellent workability.

Claims: WHAT IS CLAIMED IS: 1. An asphalt composition comprising (A) 100 parts by weight of asphalt; (B) 0.1 to 20 parts by weight of a diene liquid rubber having at least one carboxyl group, epoxy group or amino group ill the molecule; and (C) 2 to 350 parts by weight of (i) a fibrous-filler; or (ii) at least one filler selected from the group consisting of wood flour, talc, calcium carbonate, clay, carbon black, and white carbon, having a grain size of 200 microns or less. 2* The composition of claim 1., wherein said asphalt is a straight asphalt. 3. The composition of claim 2, wherein the diene liquid rubber is a butadiene homopolymer having a carboxyl group in the molecule. 4. The composition of claim 2, wherein the diene liquid rubber Is a butadiene homopolymer having an epoxy group in the molecule. 5. The composition as claimed in claim 2, wherein the straight asphalt has a penetration of 40 to 100. 6. The composition of claim l or 2 or 3 or 4, wherein the-diene liquid rubber has a number average molecular weight of 500 to 8,000 and a viscosity of 2,000 poises or less at 300C. 7. The composition of claim 1, wherein the filler is asbestos, 8. An asphalt composition comprising (A) 100 parts by weight of asphalt; (B) 0.1 to 20 parts by weight of a diene liquid rubber having at least one carboxyl group, epoxy group or amino group in the molecule; (C) 2 to 350 parts by weight of (i) a fibrous filler or (il) at least one filler selected from the group consisting of wood flour, talc, calcium carbonate, clay, carbon black and white carbon, having a grain size of 200 microns or less; and (D) @ to 50 parts by weight of a resinous tackifier. 9. The composition of claim 8, wherein the asphalt is- a straight asphalt. 10. The composition of claim 9, wherein the diene liquid rubber is a butadiene homopolymer having a carboxyl group in the molecule. 11 The composition of claim 9, wherein the diene liquid rubber is a butadiene homopolymer having an epoxy group in the molecule. 12. The composition of claim 9, wherein the straight asphalt has a penetration of 40 to 100. 13. The composition of claim 9, wherein the diene liquid rubber has a number average molecular weight of 500 to 8,00Q and a viscosity of 2,000 poises or less at 300C. 14. The composition of claim 9, wherein the filler is asbestos. 15. The composition of any one of claims 9, 10, I1, 12, 13 or 14, wherein the resinous tackifier is a petroleum resin having a softening point of from 70 to 1500C. 16. A vibration-damping sheet formed from asphalt composition comprising: (A) 100 parts by weight of a straight asphalt; (B) 0.1 to 20 parts by weight of a diene liquid rubber having a carboxyl group, an epoxy group or an amino group in the molecule; and (C) 2 to 350 parts by weight (i) a fibrous filler or (ii) at least one filler selected from the group consisting of wood flour, talc, calcium carbonate, clay, carbon black, and white carbon, having a grain size of 200, microns or less.

Inventors: KIMURA, TSUTOMU, KURASHIGE, TOMOZO, OHNAKA, KIYOSHI, SHIMADA, HIDETOSHI
Applicants: IDEMITSU KOSAN COMPANY LIMITED
Application year: 1981
Main classification: C08L95
IPC codes: C08L95