JP2012144818A - Heat-resistant flame-retardant sound absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly flame-retardant, heat-resistant and sound-absorbable sound absorber without heat shrinkage or wear even if it is repeatedly exposed to high temperatures for long hours in an automobile engine room.SOLUTION: A heat-resistant flame-retardant sound absorber includes a nonwoven cloth of 5-50 mm in thickness provided with a binder of 30-200 dry g/m. The binder is made by blending a phosphorus-based flame retardant into a nonwoven cloth with a weight of 200-2000 g/m, which is made from polyester fiber in 80-50 weight% and polyphenylene sulfide fiber in 20-50 weight% which are subjected to a processing of cotton blending-carding-wrapping-needle punching. The nonwoven cloth has 50% or more of tensile strength and elongation and 5% or less of thermal shrinkage in the condition where the cloth is cooled down to room temperature after being left under atmosphere of 200°C×500 hours.

Description

  The present invention relates to a heat-resistant and flame-retardant sound-absorbing material, and more particularly to the above-mentioned heat-resistant and flame-retardant sound-absorbing material which is suitable for the purpose of sound absorption, sound insulation and heat insulation around an automobile engine.

  In the engine room of automobiles, various soundproofing materials are installed on the back of the hood, under the engine, between the engine and the cabin, or on the muffler to prevent the sound generated from the engine from resonating. Is used. These engines, mufflers, etc. reach over 300 ° C during normal use, but more recently, due to the narrowing of the engine room, the engine cover parts are downsized and the temperature rise in the engine room becomes noticeable. Heat resistance and flame retardancy are essential for this.

  However, conventional sound-absorbing materials using 100% polyester fiber do not have sufficient heat resistance, and improvements are required. In the past, many of these heat-resistant flame retardant and soundproofing materials used were made of cheap rock wool or glass fiber. Organic fibers have come to be used.

Therefore, recently, especially heat-resistant organic fibers with a melting temperature of 350 ° C or higher such as aramid fibers are used, and silicate minerals, alumina particles, mica particles, etc. are combined as flame retardant and heat-resistant components to further give heat resistance. Nonwoven fabric is introduced as a heat-resistant sound-absorbing material. (For example, see Patent Documents 1, 2, and 3)
In addition, a stitch bond nonwoven fabric using flame-resistant fibers obtained by oxidizing acrylic synthetic fibers is also introduced. (For example, see Patent Document 4)

JP 2006-138935 A JP 2006-321053 A JP-A-6-212593 JP 2006-195104 A

  However, the former method has a difficulty that inserting and adhering heat-resistant inorganic particles between heat-resistant organic fibers requires a complicated process, and the latter method uses extremely fragile flame-resistant fibers. In addition to the problem that the method of making a nonwoven fabric is limited to stitch bonding and it is difficult to obtain a high-density nonwoven fabric, there is also a problem that it becomes very expensive in terms of price.

  In view of the actual situation as described above, the present invention is a general-purpose fiber, focusing on how to combine a general-purpose fiber and a heat-resistant organic fiber, and how to provide a flame retardant. It is intended to provide a nonwoven fabric having a desired function by blending a relatively inexpensive polyphenylene sulfide fiber (hereinafter abbreviated as PPS) into a polyester fiber, carding, wrapping, needle punching, and flame-retardant resin processing. is there.

That is, the feature of the present invention that meets the above-mentioned purpose is that a non-woven fabric having a basis weight of 200 to 2000 g / m ² obtained by blending 80 to 50% by weight of polyester fiber and 20 to 50% by weight of polyphenylene sulfide fiber with a blended cotton-card-wrapping-needle punch process. A non-woven fabric having a thickness of 5 to 50 mm formed by applying a binder containing a phosphorus-based flame retardant at 30 to 200 dry g / m ² , and in particular in a state cooled to room temperature after being left in an atmosphere of 200 ° C. for 500 hours. The heat-resistant flame retardant sound absorbing material has a low decrease in sound absorbing performance and has a tensile strength and elongation retention rate of 50% or more and a heat shrinkage rate of 5% or less.

  According to the present invention, after being left in an atmosphere at a temperature of 200 ° C. × 500 hours, the tensile strength and elongation in a state cooled to room temperature have a retention of 50% or more, and the thermal shrinkage is 5%. It is possible to provide a flame-retardant type sound-absorbing material that has no thickness and has good sound-absorbing performance, and it can be used as a sound-absorbing cover or binder sheet for automobile engines, which significantly reduces outside noise. It has a remarkable effect that can.

It is the graph which contrasted and showed each normal incidence sound absorption coefficient of the nonwoven fabric which concerns on this invention, and a comparative nonwoven fabric, (A) is the nonwoven fabric which concerns on Example 3 of this invention, (B) is the nonwoven fabric which concerns on the comparative example 1, ( C) shows the normal incident sound absorption coefficient of the nonwoven fabric according to Comparative Example 2, and (d) shows the respective normal incidence sound absorption coefficient of the nonwoven fabric according to Comparative Example 3.

  Hereinafter, specific embodiments of the present invention will be described in detail. In the present invention, as described above, a polyester fiber, which is a general-purpose fiber, and a polyphenylene sulfide fiber are used as a sound-absorbing material. These two fibers are mixed and formed into a nonwoven fabric by carding, wrapping, and needle punching. It is configured as a sound absorbing material. Here, the former general-purpose polyester fiber is effective in improving sound absorption performance and reducing the total cost, and the latter polyphenylene sulfide fiber is effective in improving heat resistance. Can be obtained.

  Here, as a polyester fiber, it is desirable that it is the range of fiber diameters 1.3-6.6 dtex, and 1.3-2.2 dtex is more suitable. As the fiber cross section, round (hollow), round (solid), and irregular cross sections such as triangles can be used. Especially, fibers with hollow cross section and irregular cross section have much sound scattering and greatly improved sound absorption performance. . On the other hand, the polyphenylene sulfide fiber desirably has a fiber diameter in the range of 1.3 to 6.6 dtex, and more preferably 1.3 to 2.2 dtex.

  The blending ratio of these polyester fibers and polyphenylene sulfide fibers is preferably in the range of 80 to 50% by weight to 20 to 50% by weight, more preferably 75 to 60% by weight to 25 to 40% by weight. When the ratio of polyphenylene sulfide fiber is 20% by weight or less, the tensile strength and the elongation retention rate are not more than 50% in the heat resistance test at 200 ° C. × 500 hours. However, it is not preferable because the total cost increases.

The polyester fiber and polyphenylene sulfide fiber are blended and blended at a required ratio and formed into a non-woven fabric by carding, lapping and needle punching. The mixed cotton-card-wrapping-needle punching non-woven fabric absorbs sound. the can ensure performance basis weight 200 to 2000 g / m ^2, it is necessary thickness 5 to 50 mm, preferably a basis weight 400~1000g / m ^2, thickness 10 to 25 mm. When the weight per unit area is 400 g / m ² and the thickness is 10 mm or less, the sound absorption performance in the low frequency region is lowered, and when the basis weight is 1000 g / m ² and the thickness is 25 mm or more, the sound absorption property in the high frequency region is gradually decreased.

  The mixed cotton-card-wrapped web is then subjected to needle punching in order to entangle the fibers. The conditions for needle punching are not particularly limited, and needle punching is performed under normal nonwoven fabric production conditions. Processing is sufficient. However, if excessive punching is performed, the porosity becomes small, the density between fibers increases and sound is easily transmitted, which is not preferable, and poor resin impregnation occurs during the subsequent resin processing, and the sound absorption performance is reduced. It causes variation and is not preferable. Therefore, needle punching is not performed once when the lapped web has a large basis weight, but the web is divided into a plurality of times, and the needle punching is performed by changing the needle depth while sequentially laminating. It is preferred to do so.

  In this way, dividing the web into a plurality of parts and performing the needle punching in a plurality of times is problematic in that the web is too bulky for needle punching at one time, and the needle depth is divided into a plurality of times. The reason why the needle punching is performed with the depth gradually reduced is to increase the porosity as much as possible and to obtain sound absorption performance. Note that it is preferable to perform needle punching by decreasing the needle depth one after another by dividing it into about 3 to 4 times according to the basis weight of the web.

  Moreover, since the shape stability of the nonwoven fabric is insufficient only by needle punching and various mechanical strengths are not sufficient, resin processing with a binder is required. In that case, it is necessary to use a flame retardant in order to impart flame retardancy, but in view of recent environmental measures, it is necessary to use a halogen-based flame retardant that may emit harmful substances such as dioxin. Although it is not preferable, even if it is somewhat expensive, it is preferable to use a phosphorus-based flame retardant.

  Phosphorus flame retardants include phosphoric acid esters such as resorcinol bisdiphenyl phosphate, guanidine phosphates with 1 to 2 moles of guanidine, or ammonium polyphosphate salts that are powders. The phosphoric acid ester system, which is preferably emulsified in a liquid form, is suitable because of its relatively good compatibility with the binder.

  As binders that can be used, polyacrylate copolymers, water-based polyester resins, water-based polyurethane resins, styrene-butadiene-based latex, etc. can be used, but water-based polyester resins and water-based resins with little flame retardance inhibition. A urethane resin is preferred.

As the dry coating weight of the binder containing a flame retardant, it requires 30 to 200 g / m ² to nonwoven, mechanical strength and flame retardancy, such as sufficient tensile strength in 30 g / m ² or less obtained In addition, if it is applied at 200 g / m ² or more, the space between the fibers is filled with a binder, and a decrease in sound absorption performance is recognized, which is not preferable. The ratio of the flame retardant and the binder is not generally determined by the required flame retardant performance and the type of flame retardant and the type of binder, but in the case of a typical phosphate ester flame retardant and aqueous polyester resin, In the active ingredient ratio, the flame retardant / binder resin is in the range of 1: 0.3 to 6, preferably in the range of 1: 0.5 to 3, the dry adhesion amount is 5 to 35% by weight of the fiber basis weight, 10 to 25% by weight is preferred.

  Thus, since the obtained non-woven fabric is used as a heat-resistant flame retardant and sound-absorbing material and exhibits its effectiveness, the tensile strength and elongation are maintained particularly after being left in an atmosphere of 200 ° C. for 500 hours and then cooled to room temperature. It is preferable that the rate is 50% or more and the heat shrinkage rate is 5% or less. If the retention rate is 50% or less and the shrinkage rate is 5% or more, the morphological change increases and the soundproofing effect is hindered.

  Hereinafter, the present invention will be described with reference to examples. However, it goes without saying that the present invention is not limited to these examples. In the examples and comparative examples, “%” is based on weight unless otherwise specified.

After weighing 30% by weight of polyphenylene sulfide fiber (manufactured by Toyobo) with a fineness of 2.2 decitex and a fiber length of 60 mm and 70% by weight of regular polyester fiber (manufactured by Toray) with a fineness of 2.2 decitex and a fiber length of 51 mm, mixed cotton, carding, after a lapping step, the needle count No. 40 basis weight 250 g / m by ² with a (organ made FPD1-40), sequentially laminated while needle depth 9 mm, penetrometer number 60n / cm ^2, needle depth 8 mm, penetrometer number 60n / Cm ² , needle depth 6 mm, penetrating number 60 n / cm ² , needle depth 4 mm, penetrating number 60 n / cm ^2, needle punching was performed to obtain a nonwoven fabric having a basis weight of 1000 g / m ² . Next, the nonwoven fabric was impregnated and squeezed into a liquid prepared by mixing 6% by weight of a phosphoric ester flame retardant (concentration 80%) and 3% by weight of a water-based polyester resin (concentration 42%), and kept at a hot air temperature of 150 ° C. A heat-resistant and flame-retardant nonwoven fabric having a dry adhesion amount of 120 g / m ² , a total product basis weight of 1120 g / m ² , and a thickness of 20 mm was obtained by drying and heat treatment for 5 minutes in a continuous heat treatment machine.

Cotton blended after weighing 25% by weight of polyphenylene sulfide fiber (manufactured by Toyobo) with a fineness of 2.2 decitex and fiber length of 60 mm and 75% by weight of regular polyester fiber (manufactured by Toray) with a fineness of 2.2 decitex and fiber length of 51 mm. After passing through the carding and wrapping steps, the needle depth is 250 g / m ² with a needle count of 40 (organ FPD1-40), and the needle depth is 9 mm, the number of pens is 60 n / cm ² , the needle depth is 8 mm while being sequentially laminated. Needle punching was performed at a penetrating number of 60 n / cm ² , a needle depth of 6 mm, a penetrating number of 60 n / cm ² , a needle depth of 4 mm, and a penetrating number of 60 n / cm ² to obtain a nonwoven fabric having a basis weight of 1000 g / m ² . Next, the nonwoven fabric was impregnated and squeezed into a liquid prepared by mixing 6% by weight of a phosphoric ester flame retardant (concentration 80%) and 3% by weight of a water-based polyester resin (concentration 42%), and kept at a hot air temperature of 150 ° C. A heat-resistant and flame-retardant nonwoven fabric having a dry adhesion amount of 120 g / m ² , a total product basis weight of 1120 g / m ² , and a thickness of 20 mm was obtained by drying and heat treatment for 5 minutes with a continuous processing machine.

A coarse layer is composed of 20% by weight of polyphenylene sulfide fiber (manufactured by Toyobo) having a fineness of 2.2 decitex and a fiber length of 60 mm, and 80% by weight of regular polyester fiber (manufactured by Toray) having a fineness of 2.2 decitex and a fiber length of 51 mm. 2 decitex, polyphenylene sulfide fiber (manufactured by Toyobo) with a fiber length of 60 mm, 20% by weight and regular polyester fiber (manufactured by Teijin) with a fineness of 1.3 decitex and a fiber length of 38 mm, made into a dense layer. After passing through the wrapping and wrapping steps, needle punching was performed at a needle depth of 14 mm and a penetrating number of 60 n / cm ² with a needle count of 40 (organ FPD1-40) to obtain a nonwoven fabric having a basis weight of 500 g / m ² . Next, the nonwoven fabric was impregnated and squeezed into a liquid prepared by mixing 6% by weight of a phosphoric ester flame retardant (concentration 80%) and 3% by weight of a water-based polyester resin (concentration 42%), and kept at a hot air temperature of 150 ° C. Drying and heat treatment were performed for 5 minutes in a continuous heat treatment machine to obtain a heat-resistant and flame-retardant nonwoven fabric having a dry adhesion amount of 60 g / m ² , a total product basis weight of 560 g / m ² and a thickness of 10 mm.
(Comparative Example 1)
After weighing 10% by weight of polyphenylene sulfide fiber (manufactured by Toyobo) with a fineness of 2.2 decitex and a fiber length of 76 mm and 90% by weight of regular polyester fiber (manufactured by Unitika) with a fineness of 2.2 decitex and a fiber length of 51 mm, mixed cotton, carding, after a lapping step, the needle count No. 40 basis weight 250 g / m by ² with a (organ made FPD1-40), sequentially laminated while needle depth 9 mm, penetrometer number 60n / cm ^2, needle depth 8 mm, penetrometer number 60n / Cm ² , needle depth 6 mm, penetrating number 60 n / cm ² , needle depth 4 mm, penetrating number 60 n / cm ^2, needle punching was performed to obtain a nonwoven fabric having a basis weight of 1000 g / m ² . Next, the nonwoven fabric was impregnated and squeezed into a liquid prepared by mixing 6% by weight of a phosphate ester flame retardant (concentration 80%) and 3% by weight of a water-based polyester resin (concentration 42%), and kept at a hot air temperature of 150 ° C. Drying and heat treatment were carried out for 5 minutes by a conveyor type continuous heat treatment machine to obtain a heat-resistant and flame-retardant nonwoven fabric having a dry adhesion amount of 120 g / m ² , a total product of 1120 g / m ² and a thickness of 20 mm.
(Comparative Example 2)
After weighing 100% by weight of regular polyester fiber (Unitika) with a fineness of 2.2 decitex and a fiber length of 51 mm, after passing through blending, carding and wrapping processes, weighs 250 g with needle number 40 (Organic FPD1-40). / M ² , while sequentially laminating, needle depth 9 mm, penetrating number 60 n / cm ² , needle depth 8 mm, penetrating number 60 n / cm ² , needle depth 6 mm, penetrating number 60 n / cm ² , needle depth 4 mm, Needle punching was successively performed at a penetrating number of 60 n / cm ² to obtain a nonwoven fabric having a basis weight of 1000 g / m ² . Next, the nonwoven fabric was impregnated with a solution prepared by mixing 6% by weight of a phosphoric ester-based flame retardant (concentration 80%) and 3% by weight of a water-based polyester resin (concentration 42%), and a conveyor maintaining the temperature of hot air at 150 ° C. A heat-resistant and flame-retardant nonwoven fabric having a dry adhesion amount of 120 g / m ² , a total product basis weight of 1120 g / m ² , and a thickness of 20 mm was obtained by drying and heat treatment for 5 minutes in a continuous heat treatment machine.
(Comparative Example 3)
Mixing cotton, carding, after weighing 30% by weight of polyphenylene sulfide fiber (made by Toyobo) with a fineness of 2.2 decitex, fiber length of 60 mm, and 70% by weight of flame retardant polyester fiber (made by Toyobo) with a fineness of 3.3 dtex and a fiber length of 51 mm After passing through the lapping process, needle weight of No. 40 (organized FPD1-40) with a basis weight of 250 g / m ² , while successively laminating, needle depth 9 mm, penetrating number 60 n / cm ² , penetrating depth 8 mm, penetrating number 60 n / Needle punching was performed at a needle depth of 4 mm and a penet number of 60 n / cm ² on a cm ² , needle depth of 6 mm, and a penet number of 60 n / cm ² to obtain a nonwoven fabric having a basis weight of 1000 g / m ² . Next, the nonwoven fabric was impregnated and squeezed into a liquid prepared by mixing 6% by weight of a phosphoric ester flame retardant (concentration 80%) and 3% by weight of a water-based polyester resin (concentration 42%), and kept at a hot air temperature of 150 ° C. A heat-resistant and flame-retardant nonwoven fabric having a dry adhesion amount of 120 g / m ² , a total product basis weight of 1120 g / m ² , and a thickness of 20 mm was obtained by drying and heat treatment for 5 minutes in a continuous heat treatment machine.

Next, the characteristics of the nonwoven fabric and the nonwoven fabric for sound absorbing material obtained from the above Examples and Comparative Examples were evaluated based on the following property evaluation method.
(Characteristic evaluation method)
Length: Measured based on JIS L1913 6.1 method Weight: Measured based on JIS L1913 6.2 method Heat resistance: Measured thermal shrinkage and tensile strength after 200 ° C. × 500 hours
Measuring machine Tensilon type tensile tester, test piece width 20mm, tensile speed 40mm / min.
Flame retardancy: According to the combustion test method UL94 V-0. However, the combustion drop was regarded as acceptable.

Sound absorption: In accordance with JIS A1405-2, a normal incident sound absorption test after 200 ° C. × 500 hours was performed. The evaluation results are shown in Table 1 below. In addition, the normal incident sound absorption coefficient of the example compared with each comparative example is shown in FIGS. From Table 1 and FIGS. 1 (a) to (d), it is understood that the heat-resistant and flame-retardant sound absorbing material according to the present invention has an excellent performance as compared with the comparative sound absorbing material.

  The sound-absorbing material of the present invention is particularly effective as a sound-absorbing material having heat resistance and flame retardancy, which is used in a cover material that can prevent and reduce the temperature increase in the engine room due to heat generation of the engine due to the recent narrowing of the engine room of automobiles. is there.

Claims (2)

30 to 50% by weight binder of 20 to 50% by weight of polyester fiber and 20 to 50% by weight of polyphenylene sulfide fiber are mixed with cotton, card, wrapping and needle punching, and a non-woven fabric with a basis weight of 200 to 2000 g / m ² is mixed with a phosphorus flame retardant. It consists of a non-woven fabric having a thickness of 5 to 50 mm provided with 200 dry g / m ^2, and after holding it in an atmosphere of 200 ° C. for 500 hours and then cooling it to room temperature, the retention rate of tensile strength and elongation is 50% or more. A heat-resistant flame-retardant sound-absorbing material characterized by having a heat shrinkage rate of 5% or less.   The heat-resistant and flame-retardant sound-absorbing material according to claim 1, wherein the web is divided into a plurality of pieces, and needle punching is performed by sequentially decreasing the needle depth while laminating.

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