JPH0223341B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical Field> The present invention is a vibration damping sheet that is attached to a vibrating metal base such as a vehicle floor surface to attenuate the source of vibration, and the upper surface of the adhesive layer is coated with petroleum-based hydrocarbon resin, It relates to a constraining layer formed of a compound containing an inorganic filler and a plasticizer. <Background Art> In order to obtain a large vibration damping force, the material for the restraining layer in a vibration damping sheet is desired to have not only high rigidity but also good adhesion to the adhesive layer. Therefore, it is required to exhibit good fluidity when heated and melted, and furthermore, vibration damping sheets are often subjected to impact from flying stones etc. through the vehicle floor while driving on rough roads, so impact resistance is also required. . If a crack occurs in the restraining layer due to poor impact resistance, the vibration damping performance will be significantly reduced. In order to meet the above requirements, a patent application filed by the same person as the applicant (Japanese Patent Application No. 58-170109, filing date:
On September 15, 1980 (see Japanese Patent Application Laid-Open No. 60-65929), petroleum resin,
Formulations containing inorganic fillers and plasticizers have been proposed. When a restraining layer is formed with this compound, a large vibration damping force can be obtained and the impact resistance is also excellent, but even though it contains plasticizers, the fluidity of the compound is insufficient, making it difficult to work during molding etc. was not necessarily good. If a large amount of plasticizer is added to obtain sufficient fluidity, the above problem can be solved, but on the other hand, the rigidity of the constraining layer, that is, the vibration damping force is greatly reduced, which is not desirable. <Disclosure of the Invention> In view of the above, the present invention provides a vibration damping sheet in which a constraining layer is formed of a compound containing a petroleum resin, an inorganic filler, and a plasticizer, which hardly causes a decrease in damping force. The purpose is to improve the fluidity of the constrained layer material. The vibration damping sheet of the present invention achieves this object by making the resinous material contain an acid-modified hydrocarbon resin and/or a carboxylate thereof. <Description of each component> In the following description, the number of blended parts "parts" is a weight unit unless otherwise specified. As shown in FIG. 1, the damping sheet has a restraining layer 2 formed on the upper surface of an adhesive layer 1. The adhesive layer 1 is formed in the same manner as a conventional adhesive sheet. That is, it is made by kneading various rubber compounds or blending them with asphalt using a kneader or the like and extruding the mixture. As the rubber material here, various rubbers such as NBR, IIR, EPDM, and SBR, or recycled rubber thereof can be used. The thicker the adhesive layer 1, the greater the vibration damping effect.
From the standpoint of weight reduction, it is usually 0.05 to 5 mm (preferably
0.2~2mm). The constraining layer 2 is made of the following resinous material (A) with an inorganic filler.
(B) and plasticizers (C). (A) Resin-like substances...Acid-modified hydrocarbon resins (hereinafter referred to as "acid-modified resins") and/or their carboxylates (collectively, "acid-modified resins")
). Here, the acid-modified resin refers to a petroleum resin modified with oxidation or ethylenically unsaturated carboxylic acid (including anhydride). The acid value of this acid-modified resin is usually 3-60. The above carboxylate is obtained by esterifying an acid-modified resin with alcohol so that the acid value becomes 2/3 or less, or by reacting it with a metal hydroxide. The content of acid-modified resins in the resinous substance is usually 100%, but it may be mixed with unmodified petroleum resin. Examples of the petroleum resin include synthetic polyterpene, aliphatic, aromatic, cycloaliphatic, unsaturated hydrocarbon and hydrogenated products thereof, which are commercially available with a softening point of 60 to 130°C. Here, from the viewpoint of impact resistance (flexibility) of the constraining layer, it is desirable to use a material other than aromatic. Examples of ethylenically unsaturated dicarboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, citraconic acid, 1,2-diethylmaleic acid and their anhydrides; - A conjugated diene such as butadiene or isoprene may be added by Diels-Alder reaction. Examples of the metal hydroxide include KOH, NaOH, Ca(OH) ₂ and the like. (B) Inorganic filler: refers to one or a mixture of two or more selected from silicon compounds mainly composed of SiO ₂ and calcium carbonate (heavy/light) or barium sulfate (barite powder/sedimentable). . The form of the inorganic filler may be either powder (powder, flake, granule, etc.) or fiber, the former having a size of 0.5 to 500 μm, and the latter having a length of <25 mm. The group of silicon compounds mainly composed of SiO ₂ mentioned above includes powdered clay (hard clay).
soft), talc, milled glass, glass flakes, fibrous glass fibers, etc.
Furthermore, as special materials, inorganic foams such as white glass balloons, glass balloons, and foam stones with a bulk specific gravity of <0.6 can also be used. When this inorganic foam is used, the weight of the constraint layer can be reduced. The amount of inorganic filler blended is usually 100 parts of resinous material (A).
100 to 800 copies. (C) Plasticizers: In addition to various ester plasticizers, process oils, natural oils such as castor oil and linseed oil, polymer oils such as polybutene, liquid resins such as liquid hydrocarbon resins, alkyd resins, xylene resins, etc. including. Examples of ester plasticizers include dibutyl phthalate, di(2-ethylhexyl) phthalate (DOP), di-n-butyl adipate, dimethyl isophthalate, di-n-butyl sebacate, which generally have good compatibility with the above resinous substances. Preferred are di-n-butylnurate, di-n-butyl fumarate, di-n-butylstearate, and the like.As the process oil, paraffinic or naphthenic oils having good compatibility with the above-mentioned resinous substances are preferred. The constraining layer 2 can be easily formed by pouring, brushing, or rolling a mixture of heat-molten resinous substances, inorganic fillers, and the above-mentioned plasticizers onto the upper surface of the constraining layer 1. It is possible to form a product with a predetermined thickness. From the viewpoint of weight reduction, the thickness of the constraining layer 2 is desirably as thin as possible within a range that still provides a constraining effect, and is usually 0.05 to 10 mm (preferably 0.2 to 3 mm). As shown in Fig. 2, the vibration damping sheet having the above structure is set on the vehicle floor surface 3 and then heat-treated through a drying oven, whereupon it becomes thermally softened or fluidized and fully conforms to the vehicle floor surface, and is then cooled. Then, the restraint layer 2 becomes substantially rigid and is adhered to the vehicle floor surface 3 as shown in FIG. <Example> The adhesive layer was made by kneading the above composition in a kneader and then extruding it into a 1 mm thick sheet.
It was cut and formed into a 200mm opening. (Composition) Recycled butyl rubber 100 parts Tackifier (aromatic hydrocarbon resin; Softening point
100°C) 80 parts heavy calcium carbonate 300 parts polybutene 50 parts DOP 50 parts For the restraining layer, a composition for the restraining layer with the following composition using each resinous substance shown in Table 1 was melt-mixed at 180°C for 30 minutes. Then, it was poured onto the top surface of the adhesive layer to form a 2 mm thick layer. The comparative example uses unmodified synthetic polyterpene (softening point 97
°C) was used. (Blend composition) Resin-like material 100 parts DOP 10 parts Heavy calcium carbonate 350 parts After setting each of the above vibration damping sheets on a steel plate base (0.8 mm thick), thermal adhesion was performed at 140°C for 60 minutes.
This was used as a test piece for vibration damping force and impact resistance tests as a comparative example of each example. The damping effect was judged by the loss coefficient η calculated from the measurement results by the damping method in a room temperature atmosphere. Impact resistance is measured by dropping a steel ball (usually 50 g) onto the iron plate with the above test piece supported on a bridge with the iron plate side up, and measuring the weight x height (g cm) at which cracks occur in the restraining layer. )”. In addition, the fluidity of the constrained layer was determined by heating and melting 30 g of the compound of each example (comparative example) at 200°C and dropping it onto an aluminum plate from a height of 4.5 cm, and measuring the spread of the compound after dropping. The test results are shown in Table 2. <Effects of the Invention> In the vibration damping sheet of this invention, the constraining layer is made of a resin-like material mixed with an inorganic filler and a plasticizer. The fluidity of the constrained layer can be improved with almost no reduction in damping force by using the resinous material as containing an acid-modified resin and/or a carboxylate thereof. Therefore, the mixing workability of the inorganic filler, the molding workability of the constraining layer, and the workability of adhesion to the floor surface are improved. This is supported by the test results in Table 2 in the above examples. In all of the Examples, compared to the Comparative Example (unmodified petroleum resin), the damping force (loss coefficient) hardly decreases, and the impact resistance and fluidity are improved. In Examples 2 and 6, in which carboxylate modified with hydroxide was used as the resinous substance, the damping force was also improved.The reason for these is that the resinous substance has polar groups such as carboxyl groups, This is presumed to be due to better compatibility with the inorganic filler.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a partial sectional view of the vibration damping sheet of this invention.
FIG. 2 is a sectional view showing a state in which the vibration damping sheet of the present invention is adhered to the floor surface of a vehicle. 1...Adhesive layer, 2...Restriction layer, 3...Vehicle floor surface (metal base).

Claims (1)

[Scope of Claims] 1. A vibration damping sheet in which a restraining layer is formed on the upper surface of the adhesive layer, and the restraining layer is made of a resin-like material mixed with an inorganic filler and a plasticizer, wherein the resin-like material is A vibration damping sheet containing the following acid-modified hydrocarbon resin A and/or their carboxylates. (A) Acid-modified hydrocarbon resin obtained by modifying petroleum resin with oxidation or ethylenically unsaturated carboxylic acid (including anhydride).