JPH0223343B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vibration damping sheet for attenuating vibrations by attaching it to a metal substrate that generates vibrations, such as a vehicle floor surface, and which has a restraining layer formed on the upper surface of an adhesive layer. . Conventionally, vibration damping on vehicle floors, etc., has been done by setting adhesive sheets made by extruding various rubber compounds alone or by mixing them with asphalt and then heating and softening them, making them conform to the floor surface and fusing them. . However, in order to obtain a large damping force using only this adhesive sheet, the sheet must be made thicker, which is undesirable as it increases the weight of the vehicle. Therefore, an application for utility model registration (Utility Model No. 1983-35862, filing date: March 1982) filed by the same person as the applicant of the present application was filed.
(Refer to Utility Model Application Publication No. 59-141247)) proposed a vibration damping sheet with a restraining layer formed of petroleum resin or the like. Although this vibration damping sheet can provide a certain amount of damping force without increasing weight, it is not necessarily sufficient, and the impact resistance of the petroleum resin that forms the restraining layer is not good, so it is difficult to ride on rough roads. If the vehicle receives an impact from the floor due to a flying stone or the like while driving, the restraint layer may crack, which could significantly reduce vibration damping performance. Therefore, in a patent application filed by the same person as the applicant (Japanese Patent Application No. 58-142327, filing date: August 3, 1988 (see Japanese Patent Application Laid-open No. 60-32644)), it is specified that petroleum resins, etc. It has been proposed to form a constraining layer with a predetermined amount or more of an inorganic filler. This damping sheet has a large damping force,
Impact resistance is also improved to some extent. However, the impact resistance is not necessarily sufficient, and the melt viscosity of petroleum resin mixed with inorganic filler increases significantly, which means that it lacks fluidity, making it difficult to mix the inorganic filler and form the constraining layer. Furthermore, it had a negative effect on the workability of attaching the vibration damping sheet to the floor surface. In view of the above, the present invention provides a vibration damping sheet in which a constraining layer is formed of a mixture of petroleum resin and a specific inorganic filler, which improves the impact resistance and fluidity of the constraining layer without reducing the damping force. The purpose is to improve sexuality. The vibration damping sheet of the present invention achieves the above object of the present invention by forming a constraining layer of a petroleum resin mixed with predetermined amounts of a specific inorganic filler and a lubricant containing a polar atomic group. Hereinafter, the vibration damping sheet of the present invention will be explained in detail. In this specification, the compounding amount unit "part" and compounding ratio are weight units. As shown in FIG. 1, a restraining layer 2 is 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 viewpoint of weight reduction, it is usually 0.05 to 5 mm (preferably
0.2~2mm). The constraining layer 2 is made by pouring a mixture of the following petroleum resin A, inorganic filler B, and lubricant C by pouring it on the top surface of the adhesive layer 1, brushing it,
It is formed to a predetermined thickness by coating means such as roll coating. The thicker the restraint layer 2, the greater the damping force, but from the perspective of reducing the weight of the vehicle, it is desirable that its thickness be as thin as possible within the range that exerts the restraint effect;
The thickness is 0.05 to 10 mm (preferably 0.2 to 3 mm). (A) Petroleum resin...Any commercially available product with a softening point of 60 to 130°C may be used, such as synthetic polyterpene, aliphatic, aromatic, cycloaliphatic, unsaturated hydrocarbon, and hydrogenated products thereof. can be exemplified. From the viewpoint of impact resistance (flexibility) of the constraining layer, it is desirable to use a material other than aromatic. These petroleum resins serve as the base material of the restraining layer, and since they themselves have strong adhesive properties, they adhere well to the adhesive layer, reliably exert a restraining effect, and contribute to improving vibration damping properties. (B) Inorganic filler: 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, but the size of the former is 0.5 to 500 μm, and the length of the latter is <25 mm. The group of silicon compounds mainly composed of SiO ₂ mentioned above includes powdered clay (hard and soft), talc, milled glass, glass flakes, fibrous glass fiber, etc. Bulk specific gravity <
Inorganic foams such as 0.6 glass balloons, glass balloons, and foam stones can also be used. When this inorganic foam is used, the weight of the constraint layer can be reduced. These inorganic fillers increase the stiffness of the constraining layer and increase the damping force, and for unknown reasons - inorganic fillers generally tend to reduce the impact resistance of polymers - they also improve the impact resistance of resinous materials. improve sex. The blending amount of the inorganic filler should be at least 100 parts of petroleum resin from the viewpoint of achieving these effects and mixing workability.
10 copies or more, usually 100-800 copies (preferably 200-800 copies)
500 copies). (C) Lubricants...Among the lubricants for resins, fatty acids (-
Polar atoms as shown in parentheses (COOH), fatty acid amides (-CONH ₂ ), fatty acid esters (-COOR), fatty acid ketones (=CO), fatty alcohols (-OH), metal soaps (-COOM), etc. Use one that includes a group. Specifically, stearic acid, hydroxystearic acid, hydrogenated oil, etc., stearamide, hydroxysteramide, methylene bis stearamide, ethylene bis stearamide, ethylene bis hydroxy stearamide, erucic acid amide, methylol. Amides, etc., butyl stearate (n), methyl hydroxystearate, stearic acid monoglyceride, etc., ketone waxes, symmetrical aliphatic ketones derived from lauric acid, octyl alcohol, decyl alcohol,
Examples of lauryl alcohol, stearyl alcohol, etc. include magnesium stearate, zinc stearate, calcium stearate, and the like. This lubricant C containing a polar atomic group has the effect of improving the impact resistance and fluidity of the constraining layer with a small amount of blending, and the blending amount is (C)/(B)= 1/100 to 1/20 (preferably 1/70 to 1/3
0). If (C)/(B) is less than 1/100, the above impact resistance and fluidity cannot be improved, and if it exceeds 1/20, it will have a negative impact on impact resistance and the viscosity during heating and melting will decrease too much. On the contrary, it has a negative effect on workability. 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 restraining layer 2 becomes substantially rigid and is adhered to the vehicle floor surface 3 as shown in FIG. Next, the present invention will be explained in more detail based on examples. The adhesive layer was formed by kneading a compound having the composition shown below in a kneader, extruding it into a sheet with a thickness of 1 mm, and cutting the sheet into a 200 mm opening. Blending composition: 100 parts recycled butyl rubber 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 restraining layer formulation having the following composition using a lubricant containing a polar atomic group shown in Table 1 was prepared at 200°C.
After melt mixing for 30 minutes, it was poured onto the top of the adhesive layer to form a 2 mm thick layer. In addition, in the comparative example, the lubricant was added to 0 in the composition of the example. Blend composition: 100 parts of synthetic polyterpene (softening point 100°C) 350 parts of heavy calcium carbonate 8 parts of lubricant After setting each of the above vibration damping sheets on a steel plate base (0.8 mm thick), heat treatment was performed at 140°C for 60 minutes. ,
This was used as a test piece for vibration damping force and impact resistance tests for each of the Examples and Comparative Examples. The damping effect was determined by the loss coefficient η calculated from the measurement results using 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 checking the spread of the compound after falling. It was measured and expressed as the average value of the major axis and minor axis. The test results are shown in Table 1. The vibration damping sheet of this invention forms a restraining layer using petroleum resin mixed with a specific inorganic filler and a lubricant containing a polar atomic group in predetermined amounts. can improve the impact resistance and fluidity of Therefore, the mixing and coating workability of the composition for the constraining layer as well as the workability of adhering it to the floor surface are improved. This is supported by the test results in Table 1 for each of the above examples. In other words, compared to the comparative example (no lubricant added), all of the examples caused almost no decrease in damping force (loss coefficient) - in fact, they were not inferior to each other - and the impact resistance and fluidity were significantly improved. are doing. The reason for this is that the lubricant, which has a polar part (polar atomic group) and a non-polar part (higher alkyl), not only has the inherent fluidity-improving effect, but also the lubricant that has a polar part (polar atomic group) and a non-polar part (higher alkyl) has an inherent fluidity-improving effect. This is presumed to be due to the effect of intervening to improve the compatibility (compatibility) between the two.

【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. In a vibration damping sheet in which a restraining layer is formed on the upper surface of an adhesive layer, 10 parts by weight or more of the following inorganic filler A and a lubricant B containing a polar atomic group, based on 100 parts by weight of petroleum resin. A vibration damping sheet characterized in that the constraining layer is formed of a mixture of B/A = 1/100 to 1/20 (weight ratio). (A) An inorganic filler made of one or more selected from a silicon compound group mainly composed of SiO ₂ and calcium carbonate or barium sulfate.