JP2012251661A - Damping sheet for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight damping sheet for an automobile which exhibits excellent damping properties in a low frequency band of 1,000 Hz or lower at ordinary temperatures.SOLUTION: The damping sheet for an automobile is formed by laminating and integrating a fiber sheet containing a glass fiber or a carbon fiber on one surface of a foamed sheet which contains a conjugated diene-based polymer in which a temperature indicating the maximum value of loss tangent to be obtained by a dynamic viscoelastic measurement is -30 to 40°C, and has an expansion ratio of 2 to 30 times and thickness of 1 to 6 mm. The sheet has basis weight of not more than 1,000 g/mto exhibit excellent lightweight properties and excellent damping properties in the low frequency band of not higher than 1,000 Hz at ordinary temperatures.

Description

  The present invention relates to a vibration damping sheet for automobiles that is excellent in light weight and has excellent vibration damping properties in a low frequency band of 1000 Hz or less at room temperature.

  In recent years, in the fields of home appliances, buildings, automobiles, and the like, much attention has been paid to vibration control and sound insulation from the viewpoint of comfort. As such vibration and noise in the field, for example, the vibration of a driving device such as a motor in the household appliance field, the rain sound on a folded-plate roof in the construction field, and the roof or door slightly vibrated due to vibration during driving in the automobile field. The generated vibration sound and the vibration of a drive system such as an engine can be mentioned, and a damping material is used for the purpose of reducing such vibration and noise.

  Damping materials made of sound-absorbing materials and polymer materials have the characteristic that the vibration damping effect increases as the frequency of the vibration wave increases, so vibration and noise can be easily reduced in the high frequency range, but low frequency The soundproofing effect was insufficient in the area.

  In addition, since vibration during driving is mainly due to vibration waves in a frequency band of 1000 Hz or less (hereinafter referred to as “low frequency band”), an excellent vibration damping property in the low frequency band is required. Yes. For this reason, when vibration-proof and sound-proof materials made of conventional polymer materials are used as vibration-damping materials for automobiles, vibration during automobile running cannot be sufficiently suppressed, and noise is generated by vibration. The problem arises that the comfort of the time is impaired.

  Therefore, as a vibration and sound insulation material having excellent vibration damping properties in a low frequency band, Patent Document 1 discloses that one or more resin components selected from the group consisting of thermoplastic resin, rubber and thermoplastic elastomer, and inorganic A base sheet formed of a filler and having one surface formed on a bonding surface on which the vibration member is bonded, and a metal sheet laminated and integrated on the other surface of the base sheet. A vibration material has been proposed.

  However, since the vibration damping material contains an inorganic filler and a metal sheet, there is a problem that it lacks lightness. Further, the vibration damping material in which metal sheets are laminated has a problem that it is difficult to separate at the time of recycling.

Japanese Patent Laying-Open No. 2005-3019

  The present invention provides an automobile vibration damping sheet that is excellent in light weight and has excellent vibration damping properties in a low frequency band of 1000 Hz or less at room temperature.

The heat-resistant foamed sheet of the present invention contains a conjugated diene polymer having a maximum loss loss tangent obtained by dynamic viscoelasticity measurement of −30 to 40 ° C. and a foaming ratio of 2 to 30 times. A fiber sheet containing glass fibers or carbon fibers is laminated and integrated on one surface of a foamed sheet having a thickness of 0.1 to 6 mm, and the basis weight is 1000 g / m ² or less.

  Conjugated diene polymers constituting the foam sheet include conjugated diene monomer homopolymers, copolymers of conjugated diene monomers, and copolymerization of conjugated diene monomers and monomers copolymerizable with the conjugated diene monomers. Any of them may be combined. Conjugated diene polymers may be used alone or in combination of two or more.

  The conjugated diene monomer is not particularly limited, and examples thereof include conjugated diene having 4 to 12 carbon atoms such as butadiene, isoprene, piperylene, and dimethylbutadiene.

  The monomer copolymerizable with the conjugated diene monomer is not particularly limited, and examples thereof include an aromatic vinyl monomer. Examples of the aromatic vinyl monomer include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, and 4-tert-butyl. Examples thereof include styrene and tert-butoxystyrene.

  The copolymer of the conjugated diene monomer and the monomer copolymerizable with the conjugated diene monomer is preferably a copolymer containing a block obtained by polymerizing the conjugated diene monomer, and the block obtained by polymerizing the conjugated diene monomer and the aromatic vinyl monomer. A block copolymer having a block obtained by polymerizing a styrene block is more preferable, and a block copolymer having a styrene block and a vinyl isoprene block shown in Chemical Formula 1 is particularly preferable. In the vinyl isoprene block shown in Chemical formula 1, n represents the degree of polymerization of the vinyl isoprene block.

  Examples of the copolymer of a conjugated diene monomer and a monomer copolymerizable with the conjugated diene monomer include, for example, styrene-isoprene-styrene triblock copolymer (SIS) and hydrogenated products thereof, styrene-ethylene-butylene-styrene. Hydrogenated diene block copolymer or random copolymer such as copolymer (SEBS), butadiene-styrene copolymer, styrene-butadiene-styrene block copolymer, styrene-butadiene-styrene radial teleblock copolymer A triblock copolymer composed of a styrene block and a vinyl isoprene block is preferable because the resulting heat-resistant foamed sheet is excellent in buffering properties and shock absorption.

  And the temperature which shows the maximum value of the loss tangent obtained by the dynamic viscoelasticity measurement in a conjugated diene polymer is limited to -30-40 degreeC, and 0-35 degreeC is preferable. This is because the vibration damping performance of the automotive vibration damping sheet is deteriorated when the temperature indicating the maximum value of the loss tangent obtained by dynamic viscoelasticity measurement is outside the range of -30 to 40 ° C.

  In addition, the temperature which shows the maximum value of the loss tangent obtained by the dynamic viscoelasticity measurement in a conjugated diene polymer means what was measured in the following way. First, a test sheet (width 5 mm × length 24 mm × thickness 0.3 mm) made of a conjugated diene polymer was prepared, and the dynamic viscoelasticity of this test sheet was measured under the conditions of a strain amount of 0.1% and a frequency of 10 Hz. The temperature indicating the maximum value of the loss tangent obtained by measuring the temperature dispersion of dynamic viscoelasticity at a heating rate of 3 ° C./min. In addition, the temperature which shows the maximum value of the loss tangent obtained by the dynamic viscoelasticity measurement in a conjugated diene polymer can be measured using a measuring apparatus commercially available from Rheometrics under the trade name “RSA”. .

  Further, the temperature indicating the maximum value of the loss tangent obtained by dynamic viscoelasticity measurement in the conjugated diene polymer is a method of adding a plasticizer to the conjugated diene polymer, a method of adjusting the ratio of copolymer components, It can adjust by the method of selecting a monomer, the method of adjusting the ratio of a monomer component, etc.

  The foamed sheet may contain a polyolefin resin in addition to the conjugated diene polymer. The crystalline resin is not particularly limited, for example, a polyethylene resin such as high density polyethylene, an olefin resin such as a polypropylene resin such as random polypropylene, homopolypropylene or block polypropylene, a polyester resin such as polylactic acid, Polyvinyl alcohol, polyacetal, polyamide, polyvinyl chloride, polyvinylidene chloride, etc. are mentioned, but since the resulting heat-resistant foamed sheet is excellent in heat resistance and workability, polyolefin resins and polyester resins are preferred, polyethylene-based Resins, polypropylene resins and polylactic acid are preferred. In addition, crystalline resin may be used independently or 2 or more types may be used together.

  If the content of the crystalline resin in the foamed sheet is small, the heat resistance of the foamed sheet may decrease. If the content is large, the vibration damping performance of the vibration damping sheet for automobiles may decrease. 10-70 weight part is preferable with respect to 100 weight part of polymers.

  If the foaming ratio of the foam sheet is low, the lightness of the foam sheet is reduced, or the foam sheet has a high elastic modulus, and it is necessary to reduce the thickness of the foam sheet in order to maintain the light weight. The vibration damping performance in the low frequency band of the vibration damping sheet may be reduced. If the vibration damping sheet is high, the vibration damping performance in the low frequency band of the automobile vibration damping sheet is lowered, so that the vibration damping sheet is limited to 2 to 30 times. Double is preferred. In addition, the expansion ratio of a foam sheet means what was measured based on JISK7222.

  If the thickness of the foam sheet is thin, the amount of resin responsible for loss is reduced and the distribution of low-frequency vibrations to the loss layer is reduced. If the vibration performance is reduced and thick, the lightness of the vibration damping sheet for automobiles is reduced, or the installation space for the vibration damping sheet for automobiles is increased, so the thickness is limited to 0.1 to 6 mm. In addition, what is necessary is just to measure the thickness of a foam sheet using a caliper.

  In the foamed sheet, an antioxidant, a filler, a stabilizer, an ultraviolet absorber, a pigment, a flame retardant, an antistatic agent, and a plasticizer are added as necessary as long as the effects of the present invention are not impaired. The conventionally well-known additive, such as, may be added.

  A fiber sheet containing one or both of glass fiber and carbon fiber is laminated and integrated on one surface of the foam sheet. In addition, as a form of a fiber sheet, a nonwoven fabric, a woven fabric, a woven fabric, a knitted fabric, etc. are mentioned. The fiber sheet plays a role of efficiently transmitting the externally applied vibration to the foam sheet by restraining the foam sheet responsible for vibration absorption. When the fiber sheet is not laminated on the foam sheet, in the low frequency region Vibration is not easily transmitted to the foam sheet, and the vibration damping performance of the automobile vibration damping sheet may be reduced.

  The higher the rigidity expressed by the tensile modulus, etc., the more efficiently the fiber sheet transmits vibrations to the foamed sheet. Therefore, the fibers constituting the fiber sheet are bound with a thermoplastic resin or a thermosetting resin. It is preferable to wear it.

  Furthermore, the thermoplastic resin or thermosetting resin that binds the glass fiber or carbon fiber that constitutes the fiber sheet improves the heat-fusability to the foam sheet, so the conjugate that constitutes the foam sheet. It is preferably compatible with the diene polymer.

  In addition, examples of the thermoplastic resin that binds the fibers constituting the fiber sheet include polyolefin resins such as polyethylene resins and polypropylene resins, and examples of thermosetting resins include epoxy resins. Is mentioned.

Also, the basis weight of the automotive vibration damping sheet, when large, the light weight of the car for vibration damping sheet is reduced, limited to 1000 g / m ² or less, 500 g / m ² or less.

  Next, the manufacturing method of the vibration damping sheet | seat for motor vehicles is demonstrated. As a method for producing a foamed sheet, for example, a resin composition containing a conjugated diene polymer, a foaming agent and a crosslinking agent added as necessary is continuously used using an extruder, a conveyor belt casting, a plastmill, or the like. After kneading, the kneaded resin composition is molded into a sheet or rod shape to form a foamable molded product. If this foamable molded product contains a crosslinking agent, it is heated or foamed molded. When the product does not contain a crosslinking agent, the foamable molded product is crosslinked by irradiating ionizing radiation. And the foamable molded article obtained is supplied to a foaming furnace, heated and foamed to produce a foamed sheet, and the foamed sheet is cut as necessary. In addition, when a crosslinking agent is contained in the foamable molded article, the foamable molded article may be further crosslinked by irradiation with ionizing radiation.

  Another method for producing the foamed sheet is a batch type method in which the resin composition is kneaded with a mixing roll or the like, and then the kneaded resin composition is supplied into the mold and crosslinked and foamed in the mold. Also mentioned.

  The foaming agent contained in the resin composition is not particularly limited. For example, azodicarbonamide, benzenesulfonyl hydrazide, dinitrosopentamethylenetetramine, toluenesulfonyl hydrazide, 4,4-oxybis (benzenesulfonyl hydrazide) And may be used alone or in combination of two or more.

  Further, if the content of the foaming agent in the resin composition is small, the foamed sheet may not be sufficiently foamed. On the other hand, if the content is large, bubbles formed by foaming are not stable, and the foam structure of the foam is not stable. 1 to 30 parts by weight with respect to 100 parts by weight of a conjugated diene polymer having a maximum loss loss tangent obtained by dynamic viscoelasticity measurement of −30 to 40 ° C. preferable.

  Furthermore, the crosslinking agent is not particularly limited, but when a foamed sheet is produced by performing chemical crosslinking, a known organic peroxide such as dicumyl peroxide is used, and foaming is performed by sulfur crosslinking. When manufacturing a sheet, sulfur or sulfur compounds are used.

  If the content of the cross-linking agent in the resin composition is small, the resin composition may not be sufficiently cross-linked. If the content is high, the cross-linking of the resin composition proceeds so much that the elongational viscosity increases and foaming occurs. The temperature indicating the maximum value of the loss tangent obtained by dynamic viscoelasticity measurement is 0.1 to 3.0 with respect to 100 parts by weight of the conjugated diene polymer having a temperature of -30 to 40 ° C. Part by weight is preferred.

  In the above resin composition, if necessary, the foaming aid, the crosslinking aid, the antioxidant, the filler, the stabilizer, the ultraviolet absorber, as long as the effects of the present invention are not impaired. Conventionally known additives such as pigments, flame retardants, antistatic agents and plasticizers may be added.

  Examples of the method for laminating and integrating the fiber sheet on one side of the foam sheet include, for example, a method for laminating and integrating the fiber sheet on one side of the foam sheet via an adhesive or a pressure sensitive adhesive, and the fibers constituting the fiber sheet In the case of being bound by a thermoplastic resin, the fiber sheet is thermally fused and integrated on one side of the foamed sheet by melting the thermoplastic resin, and the fiber is provided on one side of the foamed sheet via a double-sided adhesive tape. For example, a method of stacking and integrating sheets may be used.

  The automotive vibration damping sheet obtained as described above can be used by laminating and integrating an adhesive layer on the other surface of the foamed sheet in a general manner, and this automotive vibration damping sheet is an excellent vibration damping sheet. Demonstrate vibration performance. In addition, it does not specifically limit as an adhesive which comprises an adhesive layer, An acrylic adhesive and a urethane type adhesive are preferable.

  The vibration damping sheet for automobiles exhibits excellent vibration damping performance by being adhered to the surface of the vibrating body by the adhesive layer, and can suppress vibration of the vibrating body and reduce vibration noise.

The automotive vibration damping sheet of the present invention contains a conjugated diene polymer having a temperature of −30 to 40 ° C., which shows the maximum loss tangent obtained by dynamic viscoelasticity measurement, and a foaming ratio of 2 to 30 times. A fiber sheet containing glass fiber or carbon fiber is laminated and integrated on one surface of a foam sheet having a thickness of 0.1 to 6 mm, and has a basis weight of 1000 g / m ² or less. And has excellent vibration damping properties in a low frequency band of 1000 Hz or less at room temperature.

  Moreover, since the vibration damping sheet for automobiles of the present invention is formed by laminating and integrating a fiber sheet containing glass fiber or carbon fiber on one surface of a predetermined foam sheet, the vibration damping sheet for automobiles is used after use. By cutting, it can be supplied to an extruder and melt-kneaded, so that it is excellent in recyclability.

  Furthermore, the automobile vibration damping sheet of the present invention can be incinerated although fibers remain as a residue, so that thermal recycling is also possible.

Example 1
Styrene-vinylisoprene-styrene triblock copolymer having a styrene block and a vinylisoprene block (trade name “HIBLER 5127”, manufactured by Kuraray Co., Ltd.), temperature indicating the maximum value of loss tangent obtained by dynamic viscoelasticity measurement: 28 ° C. ) 100 parts by weight, 12.5 parts by weight of 2-ethylhexyl phthalate (manufactured by Wako Chemical), 2.0 parts by weight of phenolic antioxidant (“Irganox 1010”, manufactured by Ciba Specialty Chemicals) and azodicarbon A resin composition comprising 4.5 parts by weight of an amide (trade name “SO-20” manufactured by Otsuka Chemical Co., Ltd.) is melt-kneaded at 120 ° C. with a plast mill, and then press-treated at 120 ° C. for 5 minutes to obtain a thickness of 1 A 4 mm foamable resin sheet was obtained.

  The resulting foamable resin sheet was irradiated with an electron beam with an irradiation dose of 3.0 Mrad at an acceleration voltage of 500 KeV, and the foamable resin sheet was subjected to a crosslinking treatment. Subsequently, the foamable resin sheet was supplied into a foaming furnace and heated at 230 ° C. to obtain a foamed sheet having a thickness of 3.0 mm and an expansion ratio of 10.1 times.

A nonwoven fabric containing carbon fibers is laminated and integrated on one side of the obtained foam sheet via a double-sided adhesive tape (trade name “Sekisui Tape # 5761” manufactured by Sekisui Chemical Co., Ltd.), and the basis weight is 386 g / m ² . A vibration damping sheet for automobiles was obtained.

The nonwoven fabric containing carbon fiber was produced using the normal card machine used when producing a nonwoven fabric. That is, a carbon fiber having a length of 64 mm and a thickness of 7 μm and a polypropylene fiber having a length of 70 mm were supplied to a card machine to obtain a kneaded nonwoven fabric. In the kneaded nonwoven fabric, the basis weights of the carbon fiber and the polypropylene fiber were adjusted to 21 g / m ² , respectively.

  The obtained kneaded nonwoven fabric was superposed on a polypropylene film having a thickness of 40 μm and needle punched to integrate the kneaded nonwoven fabric and the polypropylene film to produce a laminated sheet.

After that, the laminated sheet is sandwiched between both sides by a polytetrafluoroethylene belt, heated to 200 ° C. and subjected to room temperature pressing to melt the polypropylene film and the polypropylene fiber, and the melted polypropylene binds the carbon fibers together. A fiber sheet containing carbon fibers having a thickness of 120 μm and a basis weight of 78 g / m ² was obtained.

(Example 2)
A lightweight vibration damping material for automobile having a basis weight of 375 g / m ² is obtained in the same manner as in Example 1 except that glass fiber having a thickness of 13 μm and a length of 64 mm is used instead of carbon fiber. It was.

(Comparative Example 1)
Only the foam sheet obtained in Example 1 was used as a vibration damping sheet for automobiles.

(Comparative Example 2)
An automotive vibration damping sheet having a basis weight of 435 g / m ² is obtained in the same manner as in Example 1 except that a hard aluminum plate having a thickness of 50 μm is used in place of the carbon fiber-containing sheet described in Example 1. It was. In addition, since the obtained vibration damping sheet for automobile contains a hard aluminum plate, it cannot be supplied to the extruder after use, and further, since the hard aluminum plate is nonflammable, it includes thermal recycling. It lacks recyclability.

  The loss factor of the obtained automobile vibration damping sheet was measured in the following manner, and the result is shown in FIG.

(Loss factor)
A vibration damping material for automobiles was stuck on a SPCC steel plate having a thickness of 1.0 mm, a width of 15.0 mm, and a length of 250 mm using a double-sided tape so that the foamed sheet was on the SPCC steel plate side. Thereafter, the loss factor of the vibration damping sheet for automobiles was measured by a central vibration method at 25 ° C. using a measuring device commercially available from Rion under the trade name “SA-01”.

It is the graph which showed the measurement result of the loss factor of the damping sheet for cars obtained by the example and the comparative example.

The heat resistant foamed sheet of the present invention contains a block copolymer having a temperature at which the maximum value of loss tangent obtained by dynamic viscoelasticity measurement is −30 to 40 ° C. and having a styrene block and a vinylisoprene block. containing conjugated diene polymer, and on one side of the foam sheet thickness of 0.1~6mm expansion ratio is 2 to 30 times, made by laminating and integrating a fibrous sheet containing glass fibers or carbon fibers, The basis weight is 1000 g / m ² or less.

The conjugated diene polymer constituting the foam sheet, a copolymer of Conjugate diene monomer and the conjugated diene monomer copolymerizable with the monomers used.

As the copolymer of a conjugated diene monomer and the conjugated diene monomer and a copolymerizable monomer, block copolymer having a vinyl isoprene block shown in scan switch Ren block and of 1 is used. In the vinyl isoprene block shown in Chemical formula 1, n represents the degree of polymerization of the vinyl isoprene block.

As a copolymer of a conjugated diene monomer and a monomer copolymerizable with this conjugated diene monomer , the resulting heat-resistant foamed sheet is excellent in buffering and shock absorbing properties, so that a styrene block and a vinyl isoprene block are used. A triblock copolymer is used .

The automotive vibration damping sheet of the present invention contains a block copolymer having a temperature showing a maximum loss tangent obtained by dynamic viscoelasticity measurement of −30 to 40 ° C. and having a styrene block and a vinylisoprene block. to contain a conjugated diene polymer, and on one side of the foam sheet thickness of 0.1~6mm expansion ratio is 2 to 30 times, made by laminating and integrating a fibrous sheet containing glass or carbon fibers Since the basis weight is 1000 g / m ² or less, it is excellent in light weight and has excellent vibration damping properties in a low frequency band of 1000 Hz or less at room temperature.

Claims (6)

It contains a conjugated diene polymer having a maximum loss tangent obtained by dynamic viscoelasticity measurement of −30 to 40 ° C., a foaming ratio of 2 to 30 times, and a thickness of 0.1 to 6 mm. A vibration-damping sheet for automobiles, wherein a fiber sheet containing glass fibers or carbon fibers is laminated and integrated on one surface of a foamed sheet, and the basis weight is 1000 g / m ² or less.   The vibration-damping sheet for an automobile according to claim 1, wherein the conjugated diene polymer is a copolymer containing a block obtained by polymerizing a conjugated diene monomer.   The vibration-damping sheet for an automobile according to claim 1, wherein the conjugated diene polymer contains a block copolymer having a styrene block and a vinyl isoprene block.   The automobile sheet according to claim 1, wherein the fiber sheet is formed by binding fibers with a thermoplastic resin or a thermosetting resin.   The automotive vibration damping sheet according to claim 1, wherein the foamed sheet contains a polyolefin-based resin.   The automotive vibration damping sheet according to claim 1, wherein a pressure-sensitive adhesive layer is laminated and integrated on the other surface of the foamed sheet.

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