JPH0228457B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a material that has both rigidity and shielding properties that can be deep drawn and is useful as an interior material for automobile ceiling materials, door trims, rear shells, seat bags, trunk parts, etc. The present invention relates to a method for manufacturing nonwoven fabric. [Prior art] Conventionally, the above-mentioned interior materials include resin felt made of phenol-aldehyde condensation resin filled with fibers,
Materials that can withstand temperatures of over 100°C are used, such as foamed synthetic resin, polypropylene composites, and polypropylene cardboard. Among these materials, resin felt has excellent rigidity, heat-resistant shape retention, dimensional stability, and shielding properties, but has the drawbacks of poor moldability, impact resistance, and lightness. Furthermore, polypropylene cardboard has excellent rigidity and light weight, but on the other hand, it is poor in deep drawing, and because it uses a corrugated member, its strength is directional. Furthermore, foamed synthetic resins such as polystyrene are excellent in lightness, but have the drawbacks of poor moldability and bending resistance, and also have problems with appearance after molding.
No material has been obtained that satisfies all of the performance requirements for interior materials, namely, rigidity, appropriate flexibility, lightness, dimensional stability, heat-resistant shape retention, and moldability. On the other hand, fibers such as polyethylene, polypropylene, and low melting point (140°C) polyester are used as a fiber binder, and a fiber mat made of synthetic fibers is needled to temporarily bind the fibers of the upper and lower layers of the web, and then heated to Melt the fiber binder,
Methods for producing resilient nonwoven fabrics by bonding other synthetic fibers are known. Although this nonwoven fabric is lightweight and flexible, it lacks moldability and rigidity, so it is useful as an interior material for flat areas, but it is not useful as an interior material for areas with complex shapes. . In addition, needle punched cloth has a softening point of 100 to 130℃.
After coating or impregnating an aqueous emulsion of a thermoplastic resin, the nonwoven fabric is heat-dried to remove moisture, and the nonwoven fabric is further heated and press-molded to obtain an automobile interior material. be. This interior material has the advantage that it can be installed in places with complex shapes. The fixation of the fibers of this nonwoven fabric is due to the entanglement of the fibers by needle punching and the adhesion of the emulsion resin to the fibers, but the apparent density of the nonwoven fabric to which the emulsion is applied and impregnated is 0.08~
Since it is bulky at 0.13 g/cm ² , it has the disadvantage that the filling effect with water-based emulsion resin is poor. Furthermore, since the filling effect is insufficient, there is a drawback that the shielding performance is inferior. The present inventor first developed a method for producing a nonwoven fabric using thermoplastic resin to overcome the drawbacks of poor dimensional stability and rigidity of the latter moldable nonwoven fabric without reducing its lightness, heat-resistant shape retention, and air permeability. After needling a fiber mat consisting of 15 to 50% by weight of binder fibers and 85 to 50% by weight of synthetic fibers or natural fibers having a melting point 40°C or more higher than the melting point of the thermoplastic resin, the mat is The thermoplastic resin binder fibers are heated at a temperature that melts the thermoplastic resin binder fibers but not the synthetic fibers or the natural fibers, and then the thermoplastic resin binder fibers are heated while the thermoplastic resin binder fibers remain in the molten state. Compress the fiber mat to reduce the apparent density of the mat
An aqueous emulsion of thermoplastic resin with a moldable temperature range of 80 to 180°C is adjusted to 0.15 to 0.50 g/cm ² and added to the compressed fiber mat in a proportion of the resin hardness of the emulsion to the fiber weight of the fiber mat. The type is
Provided is a method for producing a moldable nonwoven fabric, characterized in that the nonwoven fabric is obtained by coating or impregnating it to a concentration of 15 to 300% by weight, and then heating and drying at 60 to 250°C to remove moisture. 1986-87353). This method uses a combination of a thermoplastic fiber binder and a resin emulsion to improve the rigidity of the nonwoven fabric, as well as bonding the fibers together to improve dimensional stability. A major feature of this method is that it compresses and expels a portion of the air, making it possible to increase the filling rate of the emulsion resin into the mat, thereby improving the rigidity of the nonwoven fabric. However, although this moldable nonwoven fabric has excellent moldability, dimensional stability, air permeability (sound absorption), and improved rigidity, it has poor water shielding properties due to the air permeability. Furthermore, depending on the application, higher rigidity,
Some require water impermeability. We previously proposed a carpet made of resin-backed nonwoven fabric with a foam sheet adhered to the back side as a material with excellent water impermeability and rigidity. Jitsukai Showa 59
Publication No. -75034, Publication No. 59-102331
(Refer to No. 170656 and No. 57-195731) However, this method requires a backing layer formation step and a foam sheet bonding step.
In order to prevent the foam sheet from breaking due to bending, it is necessary to further laminate a non-foam sheet to the foam sheet. Furthermore, since the resin layer directly forms the surface layer, there are problems in terms of appearance. [Specific means for solving the problems] The present invention was made with the aim of improving the performance of the laying material proposed above, that is, improving shielding performance, improving rigidity, and improving appearance. This problem has been solved by combining expandable resin particles such as expandable polystyrene resin particles, an aqueous resin emulsion, and a nonwoven fabric as a backing material. That is, in the present invention, foamable thermoplastic resin particles are sandwiched between an upper layer nonwoven fabric and a lower layer nonwoven fabric to form a laminate, and the upper and lower layers are entangled by needle punching.
This needle-punched nonwoven fabric laminate is then coated and impregnated with an aqueous resin emulsion, and then the coated surface is heated to foam the expandable thermoplastic resin particles and dry the aqueous resin emulsion. The present invention provides a method for manufacturing materials. (Nonwoven Fabric) As the nonwoven fabric as the rug material in the present invention, needle punch carpets made from natural and resin fibers such as wool, nylon, polyacrylonitrile, polyacetate, and polypropylene are used. This needle punch carpet is a web obtained by needling a fiber mat made of synthetic fibers and/or natural fibers, and is manufactured by a known nonwoven fabric manufacturing method. i.e. 1.2~300
Thoroughly mix fibers with denier and fiber length of 25 to 150 mm.
The opened fibers are fed to a web forming device, and the resulting web (fiber mat and/or this web) is stacked so that the cards formed from the mixed fibers have the desired fiber weight perpendicularly. It is temporarily fixed by needling and intertwining the fibers. If some of these fibers (15 to 50% by weight of fibers based on the weight of the pine) are replaced with a resin fiber binder with a low melting point of 80 to 200°C, the strength of the resulting laying material will be further improved. As such a fiber binder, short fibers (15 to 40 mm in length) of resin such as polyethylene, polypropylene, linear polyester, and low molecular weight co-condensed polyamide are used. The raw materials for the synthetic fibers constituting the fiber mat include polyethylene terephthalate, polyamide, etc. at a temperature 40°C higher than the melting point of the thermoplastic resin fiber binder.
or higher melting point, preferably 70℃ or higher (specifically,
A thermoplastic resin having a temperature of 200 to 280°C is used. Further, as natural fibers, cotton, linen, wool, etc. are used. By sandwiching the foamable resin particles described below between the upper nonwoven fabric and the lower nonwoven fabric and performing needling, the fibers of the upper and lower layers are entangled, and the foamable resin particles are stably fixed. (Expansible thermoplastic resin particles) Expandable thermoplastic resin particles include those with a particle size of approximately 0.1 to 3 mm such as expandable polystyrene, expandable α-methylene/styrene copolymer, expandable polyethylene, and expandable polypropylene. is used. Among these, expandable polystyrene particles having a particle size of 1.5 mm or less are preferred because they are inexpensive. The expandable resin particles 1 are preferably arranged in a layered manner as much as possible between the nonwoven fabrics 2 and 2', as shown in FIG. (Aqueous resin emulsion) As a backing material, an aqueous resin emulsion that functions as a anchor for fiber mats and an adhesive for foam particles is an aqueous emulsion of a resin with a glass transition point of -65°C to +150°C, such as polyvinyl acetate, Vinyl chloride/vinylidene chloride copolymer, styrene/
Butadiene copolymer rubber, styrene/methyl methacrylate copolymer, styrene/n-butyl acrylate copolymer, ethylene/vinyl acetate copolymer,
Latexes such as styrene/n-butyl acrylate/acrylic acid copolymer, vinylidene chloride/acrylonitrile/acrylic acid copolymer, and aqueous emulsions may be used alone or in mixtures. In terms of flexibility of the non-woven fabric layer of the laying material, aqueous resin emulsion or latex with a glass transition point of 20°C or lower is preferable; conversely, in order to impart rigidity and moldability to the non-woven fabric layer of the laying material, a glass transition point of 80°C is preferred. An aqueous resin emulsion having a temperature of 0.degree. C. or higher is preferred. Aqueous emulsions with a glass transition point of 80°C or higher include (a) polyn-propyl methacrylate (Tg81°C), polystyrene (100°C), polyacrylonitrile (100°C), polymethyl methacrylate (105°C), and Methacrylic acid (130℃), polyitaconic acid (130℃), polyacrylamide (153℃)
(b) 50 to 100% by weight, preferably 65 to 95% by weight of vinyl monomers, which are raw materials for these polymers, and other vinyl monomers, such as acrylic acid. 2-ethylhexyl (Tg
-85℃), n-butyl acrylate (-54℃), ethyl acrylate (-22℃), isopropyl acrylate (-5℃), 2-ethylhexyl methacrylate (-5℃), n-propyl acrylate (8°C), n-butyl methacrylate (20°C), vinyl acetate (30°C),
℃), ethyl methacrylate (65℃), vinyl chloride (79℃), etc. or vinylidene chloride (-18℃) 50
% by weight or less, preferably from 35 to 5% by weight [in this section (b), ( )
(c) 50 to 97% by weight of a resin aqueous emulsion with a Tg of +80 to 155°C, preferably 55 to 155°C. 95% by weight and
Examples include a mixture with 50 to 3% by weight, preferably 45 to 5% by weight of an aqueous resin emulsion having a Tg of -85°C to less than +80°C. The resin solid content concentration of aqueous emulsion is usually 20~
60% by weight, and the diameter of the dispersed resin particles is
It is 10μ (microns) or less, preferably 0.05 to 10μ. Examples of aqueous resin emulsions having a glass transition point of 20°C or lower include (i) 2-ethylhexyl acrylate, n-butyl acrylate, ethyl acrylate, isopropyl acrylate, 2-ethylhexyl methacrylate, n-propyl acrylate; , n-butyl methacrylate, vinylidene chloride, ethylene, butadiene 20-100% by weight (ii) Vinyl acetate, ethyl methacrylate, vinyl chloride, n-propyl methacrylate, styrene, acrylonitrile, methacrylic acid Monomer selected from methyl, acrylic acid, itaconic acid, acrylamide, methacrylamide 80% by weight or less (iii) Monomer selected from diacetone acrylamide, maleic anhydride, diethylene glycol diacrylate 0 to 5% by weight Examples include emulsion polymers. In order to impart a sense of weight to the resulting nonwoven fabric, inorganic fillers and pigments such as calcium carbonate, iron oxide, ferrite, and barium sulfate can also be blended into this emulsion. The aqueous resin emulsion can be applied to the needled laminate 3 by sandwiching foamable resin particles between nonwoven fabrics by spraying, dipping, brushing, a foam coating machine,
This is done using a roll or the like. The amount of bucking material applied is 30 to 1000 g/m ² (solid content), preferably 80 g/m 2 (solid content).
~300g/ ^m2 . Generally, the total weight of the aqueous resin emulsion is 20 to 100% by weight (solid weight) of the weight of the nonwoven fabric. Generally, in order to completely impregnate the fiber mat with the emulsion, the applied emulsion is squeezed using squeeze rolls. The emulsion can be applied from one or both sides of the fiber mat. The fiber mat coated and impregnated with the emulsion is heated to 60 to 250°C to remove moisture, producing a nonwoven fabric. During this heating and drying process, some of the expandable thermoplastic resin particles exist in the fiber mat in the form of foam particles, and some of them fuse together to form a foam sheet, giving the laying material moldability. Provides rigidity and shielding properties. Heat drying of the applied emulsion and foaming of the expandable resin particles can be carried out by any method. For example, heating cylinders, infrared heating machines,
Although a hot air dryer, a suction dryer, etc. can be used, it is preferable to use a hot air dryer. Further, drying can be carried out at 80 to 180°C, but it is preferably carried out with hot air at 100 to 140°C in order to prevent fiber deterioration and to ensure sufficient foaming. This heating causes the foamable resin particles to expand approximately 5 to 50 times, and become foam particles with a particle size of 0.5 to 4.5 mm or a foam sheet by fusing with each other, and the resin emulsion is installed in a fiber mat backed with a resin emulsion. Ru. Furthermore, when a fiber mat containing a fiber binder is used as the nonwoven fabric, the fiber binder is melted when the emulsion is heated and dried, and the intertwining of the fibers in the fiber mat becomes stronger. (Effects) The laying material of the present invention has significantly improved rigidity and shielding properties due to the presence of the foam. Further, by heating the laying material to a temperature at which the foam melts and press-molding the laying material, the laying material can be shaped into a desired shape. Hereinafter, the present invention will be explained in more detail with reference to Examples. Manufacturing example of needle punch carpet 1 Nonwoven fabric for upper layer Polyester fiber and polypropylene fiber 350
A plain type needle punch carpet (80% polyester fiber) made of g/m ² was used. Example 2 Non-woven fabric for lower layer A fiber mat (500 g/m ² ) made of randomly stacked 15 denier polyester fibers and polypropylene fibers (melting point 164°C) with a fiber length of approximately 100 mm,
A needle-punched carpet (polyester fibers are
80%). These needle-punch carpets were used as raw rug nonwoven fabrics in the following Examples and Comparative Examples. Example 1 Expandable polystyrene particles (butane
(containing 5.5% by weight) was sandwiched at a ratio of 170 g/m ² to form a laminate, and then needling was performed from the upper layer nonwoven fabric side to entangle the upper and lower nonwoven fabric fibers. Next, as a backing material, an acrylic water-based emulsion "Acronal YJ-1650D" manufactured by Mitsubishi Yuka Verdice Co., Ltd. (trade name, resin solid content 50%, particle size 0.2 microns, film forming temperature) was applied to the entire surface of this laminate. 7℃) in an amount of 250g/m ² (solid content),
The emulsion was then impregnated into the needle punch carpet using Niprol. Then, the emulsion-impregnated needle punch carpet was heated with hot air at 130°C for 15 minutes to remove moisture and foam the expandable polystyrene particles.
A paving material was produced comprising a layer of polystyrene foam particles having a bulk density of approximately 0.18 g/cm ³ and a particle size of less than 1.5 mm. Furthermore, this laying material was heated to 140°C to soften the resin film and polystyrene foam of the backing layer, and then molded using a cooling press mold by applying a pressure of 20 kg/cm ² for 1 minute to form the interior floor of an automobile. manufactured carpets for Comparative Example 1 A material was laid in the same manner as in Example 1, except that the expandable polystyrene particles were not sandwiched (not used) between the upper and lower nonwoven fabric layers (finished wall thickness was 6 mm).
The obtained product was further molded to obtain a carpet for an automobile interior floor. Example 2 Acronal as a resin aqueous emulsion
Instead of YJ-1650D, Mitsubishi Yuka Verdate Sheet
Co., Ltd. acrylic ester/styrene copolymer emulsion “Acronal YJ-7082D” (product name,
Resin Tg approximately 120℃, solid content 50%, resin particle size approximately 0.3
A laying material having the physical properties shown in Table 1 was obtained in the same manner, except that a material (micron) was used. In addition, this laying material was heated to 140°C to soften the resin film and polystyrene foam of the backing layer, and then molded using a cooling press mold by applying a pressure of 10 kg/cm ² for 1 minute to form the interior floor of an automobile. manufactured carpets for Comparative Example 2 A laying material having the physical properties shown in Table 1 was obtained in the same manner as in Example 2 except that the expandable polystyrene particles were not used. In addition, the evaluation of the carpet is based on the following method. Three-point bending strength: A sample piece (length 150 mm, width 50 mm) is supported with a span of 100 mm, and a deformation load is applied perpendicularly to the sample piece at a rate of 50 mm/min using an Instron type testing machine at the center point of the sample. The maximum bending resistance value was measured when a load was applied. Imperviousness: Conforms to JIS A-6910 water permeability test. The water head is set to 250 mm, and the judgment is made after 12 hours. ×: Water did not penetrate through the back surface and remain. △: Water bleeding is observed on the back side. ○: No water bleed is observed on the back side. 【table】

[Brief explanation of drawings]

FIG. 1 is a sectional view of a laying material obtained by implementing the present invention. In the figure, 1 is expandable polystyrene particles, 2 is a nonwoven fabric for the upper layer, and 2' is a nonwoven fabric for the lower layer.

Claims (1)

[Scope of Claims] 1. A laminate is formed by sandwiching foamable thermoplastic resin particles between an upper layer nonwoven fabric and a lower layer nonwoven fabric, the upper and lower layers are intertwined by needle punching, and then this needle punched nonwoven fabric laminate is formed. A method for producing a rigid laying material, which comprises applying and impregnating a body with an aqueous resin emulsion, then heating the applied surface to foam the expandable thermoplastic resin particles, and drying the aqueous resin emulsion. 2. The nonwoven fabric contains 15 to 50% by weight of a resin fiber binder having a melting point of 80 to 180°C, and more than the fiber binder.
The manufacturing method according to claim 1, characterized in that the fabric is a needle-punched nonwoven fabric comprising 85 to 50% by weight of resin fibers or natural fibers having a melting point higher than 40°C. 3. The manufacturing method according to claim 1, wherein the expandable thermoplastic resin particles are expandable polystyrene particles having a particle size of 1.5 mm or less. 4. The manufacturing method according to claim 1, wherein the expandable thermoplastic resin particles are used in an amount of 10 to 200 parts by weight per 100 parts by weight of the nonwoven fabric. 5. The manufacturing method according to claim 1, wherein the resin of the aqueous emulsion is applied to the nonwoven fabric at a solid content of 30 to 1000 g/m ² .