JPH0129901B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing a nonwoven fabric that has both rigidity and elasticity and can be deep drawn and is useful as an interior material for automobile ceiling materials, door trims, rear shells, seat bags, trunk parts, etc. . [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, and dimensional stability, but has the drawbacks of poor moldability, impact resistance, air permeability, and lightness. In addition, polypropylene cardboard has excellent rigidity and lightness, but
On the other hand, it lacks breathability. Furthermore, since a corrugated member is used, the strength is directional. Furthermore, foamed synthetic resins, such as cross-linked polystyrene, have excellent lightness, but have the disadvantage of poor heat resistance, shape retention stability, and bending resistance, and do not meet the required performance as interior materials, that is, rigidity, appropriate flexibility, lightness, and dimensional stability. No material has been obtained that satisfies all of the properties of elasticity, 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 ³ , it has the disadvantage that the filling effect with emulsion resin is poor. 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 ³ 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, which is characterized in that the nonwoven fabric is obtained by applying 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. Japanese Patent Publication No. 58-87353). 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, this method for producing a moldable nonwoven fabric requires an earlier heating step to melt the binder fibers and a later heating step to dry the resin emulsion, which is not a good idea in terms of thermal energy. [Specific means for solving the problem] In the present invention, by adjusting the amount of resin in the emulsion applied to the nonwoven fabric and the compression ratio of the mat, one heating step can be omitted, and a moldable nonwoven fabric with high elasticity can be obtained. It provides: That is, in the present invention, an aqueous emulsion of a thermoplastic resin having a moldable temperature of 80 to 180° C. is added to a nonwoven fabric mat so that the resin solid content of the emulsion is 15 to 300% by weight based on the fiber weight of the nonwoven fabric mat. After coating and impregnating the emulsion resin, the nonwoven fabric mat is heated and dried at a temperature higher than the melting point of the emulsion resin to remove moisture, and then the nonwoven fabric mat is compressed to give an apparent density of 0.15 to 0.5 g/cm ^{3 .} The present invention provides a method for manufacturing a moldable nonwoven fabric, which is characterized by adjusting the shape of the nonwoven fabric. Non-woven mats are 1.2-300 denier, fiber length
25 to 150 mm natural fibers and/or natural fibers sufficiently mixed and opened are supplied to a web forming device, and cards formed from the fibers are stacked to the desired fiber weight. Manufactured by Thermoplastic resins such as polyethylene terephthalate, polyamide, and polypropylene are used as raw materials for synthetic fibers. Further, as the natural fiber, cotton, linen, wool, etc. are used. All of these may be scraps (reused items). Among these, 15 to 50% by weight of thermoplastic resin fiber binder is used as a material for non-woven mats.
The use of a fiber mixture consisting of 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 is effective in adjusting the apparent density during compression. It is convenient for A web (fiber mat) in which cards made of the above-mentioned fibers are stacked is vertically poked with a needle, and the fibers are crossed in the vertical direction to temporarily hold each card together (so-called needling). An aqueous emulsion of thermoplastic resin is added to the fiber mat so that the resin solid content of the emulsion is 15 to 300% by weight, preferably 30 to 150% by weight based on the weight of the fiber mat.
% by weight, and then heated at a temperature higher than the melting point of the emulsion resin, for example 100~
A moldable nonwoven fabric is produced by heating and drying at 250°C to remove moisture. Particularly when the mat also contains a fiber binder, the resin is heated to a temperature that dissolves the fiber binder as well as the emulsion resin, making it easier to adjust the apparent density. The thermoplastic resin of the emulsion impregnated into the fiber mat has a moldable temperature range of 80 DEG C. or higher, preferably 120 DEG to 180 DEG C., and a particle size of 0.01 to 5 microns. Specifically, styrene/acrylic acid lower ester copolymers (ester has 2 to 6 carbon atoms), methacrylate/acrylic acid lower ester copolymers, vinylidene chloride copolymers (vinylidene chloride content is 85% by weight or more) ), thermoplastic resins such as styrene-diene copolymers. Some of these products are Acronal YJ-1100D, Acronal YJ-1100D, Acronal YJ-1100D, Acronal YJ-1100D, Acronal YJ-1100D,
It is sold under product names such as Deiofan 192D. Examples of means for applying or impregnating the fiber mat with the emulsion include a licker roll, a squeezing roll, a spray gun, and dipping. 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. Also,
It is possible to impregnate the entire fiber mat, to have a partially unimpregnated portion in the center, or to have a partially unimpregnated portion on one side. By allowing the unimpregnated portion to exist in the fiber mat, the cushioning properties of the resulting nonwoven fabric can be prevented from being extremely reduced. Fillers such as calcium carbonate, iron oxide, ferrite, barium sulfate, etc. may be added to this emulsion to give the obtained nonwoven fabric a sense of weight, and fillers such as low-density polyethylene, polystyrene, ethylene, etc. may be added to give moldability. - It is also possible to blend powder of low melting point resin such as vinyl acetate copolymer. The fiber mat coated and impregnated with emulsion is heated to a temperature above the melting point of the emulsion resin to remove moisture, and the apparent density that can be molded is 0.15~
A nonwoven fabric of 0.5 g/cm ³ , preferably 0.17 to 0.3 g/cm ³ is produced. During this heat-drying process, some of the resin particles in the emulsion exist in the fiber mat in a particulate state, and some form a film, which strengthens the entanglement of the fibers and makes the fiber mat moldable. and imparts rigidity. Here, the apparent density of the moldable nonwoven fabric is 0.15~
The apparent density of 0.5g/cm ³ is 0.15g/cm ³
If it is smaller than , the space-filling effect of the mat of a binder such as an emulsion resin or a fiber binder that binds fibers to each other will be low, and the bonding force between the fibers will be small and they will easily come off. On the other hand, if the apparent density exceeds 0.5 g/cm ³ , the fiber layer becomes dense and has poor elasticity like resin felt, and the air permeability also decreases. The nonwoven fabric that has been given moldability in this way is heated on its own to a temperature above the melting point of the emulsion resin, and then compression molded into the desired shape, resulting in a molded product with a good balance of rigidity and elasticity. It will be done. At this time, decorative paper, polypropylene sheet,
By layering ABS leather sheets, polyvinyl chloride leather sheets, tufted carpets, and nonwoven fabrics and compression molding them, it is possible to obtain molded products whose surfaces are decorated with these sheets. If a reinforcing material such as a plywood board, resin felt, or cardboard is used instead of these sheets, a composite molded article in which the nonwoven fabric and these reinforcing materials are integrated can be obtained. The moldable nonwoven fabric obtained by carrying out the present invention can be used not only as an interior material for automobiles, but also as a flooring material in a house, and as an anti-slip material attached to the surface of a pallet deck board. Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that parts and percentages in the examples are based on weight unless otherwise specified. Example 1 A mixed fiber layer of 20% recycled polypropylene (melting point 164°C) fiber binder with 15 denier and fiber length of about 100 mm and 80% recycled polyethylene terephthalate (melting point 264°C) fiber with 15 denier and fiber length 75 to 125 mm was randomly created. Fiber mats piled up (870g/
m ² ) was needled using 15-18-32-3RB needles at a rate of 50 needles per square inch (approximately 7.5 mm thick). The apparent density of this needled web is 0.12
g/cm ³ , and the bending strength ^* , tensile strength, and tensile elongation were as follows.

[Table] * Fix one end of the sample piece (length 120 mm, width 30 mm),
The bending resistance value was measured when a deformation load was applied perpendicularly to the sample piece at a rate of 50 cm/min using an Instron type testing machine at a location 100 mm vertically from the fixed location. This needled web was coated with an aqueous emulsion of acrylic acid ester and styrene copolymer “Acronal 7082D” (trade name, manufactured by Yuka Verdice Co., Ltd.).
After coating the web with a resin softening point of approximately 120°C and a resin particle size of 0.1 to 0.3 microns and a solid content of 50% to a resin content of 350 g/m ² , the emulsion was impregnated into the web using a Nipprol. The water content of the emulsion was removed using a cylinder dryer (190°C), the emulsion resin was melted, and the thickness was made 5.0 mm using a cooling roll to ensure the entanglement of the fibers. The bending strength of the nonwoven fabric was 254 g/3 cm width, and the apparent density of the nonwoven fabric itself was 0.17 g/cm ^3. In addition, this moldable nonwoven fabric had good air permeability. The following method was used to measure the nonwoven fabric: After heating the nonwoven fabric to 190°C, compression molding was performed under the condition of 0.35 kg/cm ² G to form a tray-shaped container with a length and width of 200 mm and a depth of 20 mm. When water is inserted, water leaks out from the container immediately and continuously, which means good ventilation (〇), and when water soaks into the container and forms a ooze, water drips discontinuously, which means good ventilation. (△), and those that did not allow water to pass through were classified as poor breathability (x). This moldable nonwoven fabric was heated to 200°C and then press-molded to obtain a molded product with a shape faithful to the mold. Examples 2 to 5, Comparative Examples 1 to 3 The resin solid content of the emulsion blended into the fiber mat was 250 g/ ^m2 , and the pressure of the cooling roll was changed to obtain a nonwoven fabric with the thickness shown in Table 1. Manufacturing and press molding were carried out in the same manner as in Example 1, except for the following changes, to obtain moldable nonwoven fabrics and molded products having the physical properties shown in the table.

【table】

Claims (1)

[Claims] 1. The temperature at which the nonwoven fabric mat can be molded is 80°C or higher.
After coating and impregnating an aqueous emulsion of thermoplastic resin at 180°C so that the resin solid content of the emulsion is 15 to 300% by weight based on the fiber weight of the nonwoven fabric mat, the temperature is higher than the melting point of the emulsion resin. The moisture is removed by heating and drying, and the non-woven mat is then compressed to reduce the apparent density of the mat.
A method for producing a moldable nonwoven fabric, characterized by adjusting the weight to 0.15 to 0.5 g/cm ³ . 2 A fiber mat and needles in which the nonwoven fabric mat is made of 15 to 50% by weight of a thermoplastic resin fiber binder 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 manufacturing method according to claim 1, wherein the manufacturing method is a ring.