JPS5887353A - Production of moldable nonwoven fabric - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention is applicable to automatic military ceiling materials, door trims, rear shells,
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 seat backs, trunk parts, etc.

Conventionally, the above-mentioned interior materials include resin felt made of phenol-aldehyde condensation resin filled with fibers, foamed synthetic resin,
Materials that can withstand temperatures of 100°C or higher are used, such as polypropylene composites and polypropylene cardboard. Among these materials, resin felt has excellent rigidity, heat-resistant shape retention, and dimensional stability, but it also has poor moldability, impact resistance,
It has the disadvantage of poor breathability and lightness. Furthermore, polypropylene cardboard has excellent rigidity and light weight, but on the other hand, it has poor 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 drawbacks of poor heat resistance, shape retention stability, and bending resistance. No material has been obtained that satisfies all of the properties of elasticity, dimensional stability, heat-resistant shape retention, and moldability ◎ On the other hand, polyethylene and polypropylene, low 111 points (14
0°C) Using fibers such as polyester as a fiber binder, a fiber mat made of synthetic fibers is needled to temporarily bind the fibers in the upper and lower layers of the web, and then heated to melt the fiber binder and use other synthetic fibers. Methods for producing highly elastic nonwoven fabrics by bonding 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 is not useful as an interior material for areas with complex shapes.

In addition, after coating or impregnating an aqueous emulsion of thermoplastic resin with a softening point of 100 to 130°C into the needle punch hole, heat and dry it to remove water to obtain a moldable cloth, which is further heated. Automotive interior materials obtained by compression molding are known.

This interior material has the advantage that it can be installed in places with complex shapes. However, since the fibers of the nonwoven fabric are fixed by bonding the fibers together through needle punching and by adhering the emulsion resin to the fibers, the dimensional stability against external stress is inferior to that of resin felt. The apparent density of the nonwoven fabric to be applied and impregnated is O, OS ~
Since it is bulky at 0.13 f/-, the filling effect with the emulsion resin is poor and the rigidity is also poor.

The present invention aims to improve the dimensional stability of the latter formable nonwoven fabric,
- To provide a method for producing a nine-dimensional nonwoven fabric by improving its poor properties without reducing its lightness, heat-resistant shape retention, and air permeability. In addition to adhering fibers to each other to improve dimensional stability, the fiber mat is compressed to expel some of the air before applying or impregnating the emulsion, increasing the filling rate of the emulsion resin into the mat. The major feature is that it is possible to increase the rigidity of the nonwoven fabric by increasing it.

That is, in the present invention, after needling a fiber mat consisting of 15 to t% by weight of thermoplastic resin fibers, the skeleton mat is heated to a temperature at which the thermoplastic resin fibers melt but synthetic fibers or natural fibers do not melt. Heat it to make it thermoplastic! The M@-made rutted fibers are melted, and then the fiber mat is compressed while the nuclear thermoplastic resin AM is kept in a molten state to adjust the apparent density of the mat to 0.15 to 0.50 f/-. The temperature range at which this compressed fiber mat can be molded is 80~180℃.
℃ The resin solid content of the emulsion is 15 to 3% of the weight of the forged fibers of the cough fiber mat.
After coating or impregnating it to 00% by weight, 60%
This invention provides a method for producing a moldable nonwoven fabric, which is characterized by obtaining a nonwoven fabric by heating and drying at ~250°C to remove moisture.In the practice of the present invention, the fiber mat before needling is It is manufactured using a known nonwoven fabric manufacturing method. That is, 1.2-300 denier, fiber length 25-1
501 thermoplastic resin** fiber 15 to 50% by weight; 1.
Synthetic fibers of 2 to 300 denier and fiber length of 25 to 150 mm and/or natural fibers of 85 to 50 percent by weight were thoroughly mixed and processed into a web forming device, and the mixed fibers were formed. Cards are manufactured by stacking them to achieve the desired fiber weight.

The melting point of the thermoplastic resin fiber material is 90-17.
0° C. resins such as polyethylene, polypropylene, low melting point polyesters, low melting point polyamides, etc., and mixtures thereof are exemplified.

Among these, polypropylene fibers are preferable in order to impart rigidity to the moldable nonwoven fabric obtained. Such polypropylene, even if it is a propylene homopolymer, has propylene as its main component and contains olefins such as ethylene and butene. It may be a copolymer of It was,
Up to 50% by weight of the polypropylene fibers may be replaced with fibers having a melting point lower than that of the polypropylene fibers, such as polyethylene fibers.

As raw materials for the synthetic fibers, which are the other fibers that substantially constitute the fiber mat, #1 town having a melting point higher than the melting point of the thermoplastic resin, such as polyethylene terephthalate or polyamide, is 40°C or higher, preferably 70°C or higher. Plastic resin is used. Further, as natural fibers, cotton, linen, wool, etc. are used.

Are all these 1? (Reused items) may also be used.

The thermoplastic resin fibers such as polypropylene fibers as the fiber binder are used in an amount of 15 to 50, preferably 20 to 40, of the weight of the fiber mat. If it is less than 15% by weight, the contribution to improving the rigidity and dimensional stability of the resulting nonwoven fabric will be small.On the other hand, if it exceeds 50% by weight, it will become like resin felt, hard and brittle with impaired fiber texture. Become something.

Cards made of the above-mentioned fiber mixture are stacked and nine webs (
*The fiber mat) is poked vertically with a needle, and the fibers are crossed in the vertical direction to temporarily secure each card (
(so-called needling).

This needled fiber mat has a temperature at which the thermoplastic resin fibers of the fiber binder dissolve, but synthetic fibers and natural fibers having a melting point higher than the melting point of the thermoplastic resin by 40℃ or more do not dissolve, for example, 130℃ or more. The fiber binder of the polypropylene fibers 1 is melted by heating to 250°C, preferably Fi190-230°C using hot air, and then, while the fiber binder is in a molten state, the apparent density of the fiber mat is 0.15~0.50 f/m
, preferably 0.1720.30 f/-, and the molten fiber binder is cooled, and the fiber binder allows the paper-synthetic abrasives or natural fibers to become entangled in a three-dimensional structure. Obtain a combined mat.

Rather than melting the fiber binder when shaping the nonwoven fabric after impregnation with the resin emulsion, it is better to melt the fiber binder before such compression while the fiber mat has a low density (i.e., is bulky) so that heat can pass between the fibers more easily. This is because melting can be carried out in a short time.

Further, the purpose of compressing the fiber mat is to increase the filling rate of the fiber mat of the emulsion resin and improve the rigidity of the obtained nonwoven fabric.

An aqueous emulsion of thermoplastic resin is applied to this compressed fiber mat so that the resin solid content of the emulsion is 5 to 300 wt%, preferably 30 to 150% by weight based on the weight of the fiber mat.
Coating or impregnating to give 60-2%
A moldable nonwoven fabric is produced by drying in a hot oven at 50°C to remove moisture.

The thermoplastic resin of the emulsion impregnated into the fiber mat has a moldable temperature range of 80°C or higher, preferably 120°C or higher.
The particle size at 180°C is 0.01 to 5': chron. Specifically, styrene/acrylic acid lower ester (ester has 2 to 6 carbon atoms) copolymer, methacrylate/
Examples include thermoplastic resins such as lower ester copolymers of acrylic acid, vinylidene chloride copolymers (vinylidene chloride content is 85% by weight or more), and styrene-diene copolymers.

Some of these are Achronal YJ-1100D, 8393D, and 708 from Yuka Verdice ■.
It is sold under product names such as 2D and Deiofan 192D.

Examples of means for applying or impregnating the fiber mat with the emulsion include a litter roll, a squeeze roll, a spray gun, and dipping. Generally, in order to completely impregnate the fiber mat with the emulsion, the applied emulsion is squeezed by squeezing or rolling.

The emulsion can be applied from one or both sides of the fiber mat. Further, 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 non-impregnated 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 blended into this emulsion to give the obtained nonwoven fabric a sense of weight, and fillers such as low-density polyethylene, styrene, and It is also possible to blend a powder of a low melting point resin containing ethylene/vinyl acetate copolymer.

The fiber mat coated and impregnated with the emulsion is heated to 60 to 250°C to remove moisture, producing a moldable nonwoven fabric. 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 skins, which strengthen the bonds between the fibers and make the fiber mat moldable. and imparts rigidity.

F5, which has been given moldability in this way, is heated on its own to a temperature of 11 degrees above the melting point of the emulsion resin and the resin that made up the fiber binder, and then compression molded into the desired shape and stiffened. A molded product with high quality can be obtained. At this time, by layering decorative paper, polypropylene sheet, ABS leather sheet, polyvinyl chloride leather sheet, and nonwoven fabric and compression molding, it is possible to obtain a molded product whose surface is decorated with these sheets. If a me material such as a plywood board, resin felt, or cardboard s is used instead of these sheets, it is also possible to obtain a composite body in which the nonwoven fabric and these reinforcing materials are integrated.

The moldable nonwoven fabric obtained according to 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 a fastening material attached to the surface of a pallet deck board. The present invention will be explained in more detail with reference to Examples. Note that parts and numbers in the examples are based on the limited weight of paper that does not invert.

Example 1 20% recycled polypropylene (melting point 164°C) fibers of 15 denier, fiber length 100 cm and 15 denier, fiber length 7
A fiber mat (6sor/m') randomly stacked with 80% mixed fiber waste of recovered polyethylene terephthalate (melting point 2°64°C) fibers of 15-125s
Needling was performed using 32-3 RBO needles at a rate of 50 needles per square inch (approximately 6.21111 thick).

The apparent density of this needled web is 0.11f/
-, and the bending strength, tensile strength, and tensile elongation were as follows.

*One end of the sample piece (vertical 120 fins, width 30 cm) was fixed and deformed perpendicularly to the string piece at a rate of 50 degrees/min using an Instron type testing machine at a point 4C100wm in the longitudinal direction from the fixed point. The flexural resistance value was measured when a load was applied.

This needled web was heated with hot air at 200° C. for 3 minutes to melt the polypropylene fibers, and while the polypropylene was still in a molten state, the web was compressed using a cooling roll to a thickness of about 3.5 m. It was made into a web.

The compressed web had an apparent density of 0.19 t/-, and a bending strength of Of/3 ex width in both the longitudinal and transverse directions.

This compressed web was coated with acrylic ester/styrene copolymer aqueous emulsion 1-1 Acronal 7082D (trade name, resin softening point: 120°C) manufactured by Yuka Verdice.
, resin particle size 0.1 to 0.3 microns, solid content 50%) #, resin content 350f/W? After coating, the web was impregnated with the emulsion using a nip roll. Next, the moisture in the emulsion was removed using a cylinder dryer (150°C), and the emulsion resin was melted to ensure fiber bonding. did.

The bending strength of the moldable nonwoven fabric produced in this way is 220 f / 3 in the longitudinal direction, 19 in the transverse direction
It was 0f/36R width.

Example 2, Comparative Example 1 In Example 1, the degree of compression of the web before emulsion impregnation was determined by determining whether the thickness of the web was 3 mm (Example 2) or 5 mm (Example 2).
A moldable nonwoven fabric was obtained in the same manner as Comparative Example 1) except for the following changes. The longitudinal bending strength of this nonwoven fabric was as shown in the following table.

Examples 3 to 6, Comparative Examples 2 to 4 Polypropylene fiber 22 used in Example 1 as the web
% and polyethylene terephthalate fiber with a thickness of approximately 8 mm and an apparent density of 0.11 f/i.
Using a web of 860 f/- weight, this was needled, heated to melt the polypropylene fibers, and then compressed to the thickness shown in the following table.
Similarly, the emulsion was made to have a solid content of 300 s'/m'.
A moldable nonwoven fabric was obtained by coating, impregnating, and heating and drying.

The air permeability and longitudinal bending strength of this nonwoven fabric were as shown in the table below.

*After heating the nonwoven fabric to 190°C, compression molding was performed under the conditions of 0.35 Kf/iG to give a length and width of 200cm and a depth of 20cm.
When a tray-shaped container is molded and water is inserted into the container, water leaks immediately and continuously from the container. If water drips discontinuously, the air permeability is fair (Δ), and if water does not pass through at all, the air permeability is poor (x).

Example 7 In Example 6, acrylic copolymer emulsion 1
A moldable nonwoven fabric having excellent air permeability and flame retardancy was obtained in the same manner except that vinylidene chloride copolymer emulsion "Diofan 192 (trade name, manufactured by Yuka Verdeinocie Co., Ltd.) 1 was used instead of Acronal 70820'.

Comparative Example 5.6 Needled web K of Example 1 with a wall thickness of about 6.2-1 weight 680 f/m' and an apparent density of about 1 ff/or 900 f/d, and then dried in the same manner as in Example 1 to produce a moldable nonwoven fabric having the physical properties shown in the following table.

(Margins below) Frn,t,'27#ovshii As can be seen from the above table, the nonwoven fabric obtained by implementing the present invention has a weight of about 2.5% compared to conventional interior decoration materials even if it has the same weight. It exhibits ~3 times as high rigidity and also has excellent heat-resistant shape retention.

*Evaluation method for heat-resistant shape retention When a nonwoven fabric formed into a tray is stored in a room blowing hot air at 110°C for 20 minutes, those that retain their original shape are rated as good (○), and those that retain their original shape are rated as good (○). The item was marked as defective (x).

Claims (1)

Scope of Claims: After needling a fiber mat consisting of 85 to 50% by weight Ii of fibers or natural fibers, the thermoplastic resin fibers are melted, but synthetic fibers or natural II1.
The thermoplastic resin fibers are heated at a temperature that does not melt the fibers, and then the fiber mat is compressed while the thermoplastic resin fibers remain in a molten state to reduce the apparent density of the mat to 0.
15-0. sof/j, and added to this compressed fiber mat an aqueous emulsion of a thermoplastic resin having a moldable temperature range of 80 to 180°C, with a resin solid content of 15% based on the fiber weight of the fiber mat. After coating or impregnating it to 300% by weight, 60 to 250%
1. A method for producing a moldable nonwoven fabric, which comprises obtaining a nonwoven fabric by heating and drying at ℃ to remove moisture. (2) The manufacturing method according to claim 1, wherein the thermoplastic resin fiber is polypropylene fiber.