JP2009167570A - Reinforced ground fabric for expansion molding of urethane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforced fabric for expansion molding, good in compatibility with mold, resin infiltrativeness and resin leak-proofness, and to provide an expansion molded form excellent in mechanical strength and cushionability and emitting no abnormal sound, obtained using the same. <P>SOLUTION: The reinforced fabric consists of a polypropylene-based spunbonded nonwoven fabric made of crimped filaments, wherein the nonwoven fabric is 3-30% in thermocompression bonded area percentage, 0.3-10 mm<SP>2</SP>in one fused area of the thercompression bonded parts and 0.5-10 mm in the spacing between the adjoining fused areas, and 50-200 g/m<SP>2</SP>in basis weight and 0.1-2 N in tear strength determined by the pendulum method in accordance with JIS-L-1906. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cushioning material for a formable polyurethane seat that is excellent in tearing strength and hardly broken as a reinforcing base fabric for urethane foam molding, and has an excellent reinforcing effect.

As a cushioning material for vehicles and the like, a soft polyurethane foam type foamed molded body is mainly used.
The polyurethane foam is obtained, for example, by injecting a polyurethane resin stock solution into a molding concavo-convex mold and foam-molding it. The obtained cushion body is used by being mounted on a mounting steel material such as a spring, a frame, and a pipe, but an abnormal noise such as a scratching sound is generated when the vehicle is vibrated or seated.
In order to prevent the occurrence of such abnormal noise, proposals have been made to use a nonwoven fabric as a reinforcing fabric for urethane foam.
Patent Document 1 proposes a reinforcing fabric using a crimped long-fiber nonwoven fabric. By using the crimped long-fiber, it is a bulky constituent fiber and has excellent urethane resin permeability. The reinforcing cloth is easily torn by contact with the mounting steel material, and the tension at the time of mounting causes cracks, tears, perforations, etc. in the fused portion, causing problems such as resin leakage.

JP 2000-62061 A

  An object of the present invention is to provide a reinforcing cloth for urethane foam molding having a bulkiness and a high tearing strength in order to solve the above problems.

As a result of intensive studies, the present inventors have used a crimpable polypropylene-based long-fiber nonwoven fabric, the content of titanium oxide in the fiber is not more than a specific range, the porosity of the nonwoven fabric is high, and the thermocompression bonding conditions are By making mild, it is possible to adjust the degree of thermocompression bonding of the partial thermocompression bonding part, and as a result, it has been found that the tearing strength is improved and the practical handling properties such as urethane foam moldability can be improved. Reached. The invention claimed in the present application is as follows.
(1) a thermocompression bonding area ratio is 3% to 30%, one of the fused area of the thermocompression bonded portions is 0.3 to 10 mm ^2, the interval is 0.5 to 10 mm, crimped continuous fiber Is a reinforcing fabric composed of a polypropylene-based spunbonded nonwoven fabric, wherein the nonwoven fabric has a basis weight of 50 to 200 g / m ² , and has a pendulum tear strength of 1.0 N per unit basis weight as measured by JIS-L-1906. A reinforcing base fabric for urethane foam molding characterized by the above.
(2) The urethane foam-reinforced reinforcing base fabric according to (1) above, wherein the number of crimps of the crimpable long fibers is 2 to 40 pieces / 25 mm.
(3) The reinforcing base fabric for urethane foam molding as described in (1) or (2) above, wherein the crimpable long fibers have a fiber diameter of 1 to 30 μm.
(4) Reinforcement base fabric for urethane foam molding as described in any one of (1) to (3) above, wherein the thermocompression bonding temperature is 100 to 145 ° C. and the pressure is 10 to 700 kPa / cm. .
(5) The reinforcing foam for urethane foam molding according to any one of (1) to (4) above, wherein the continuous fiber nonwoven fabric has a pore volume ratio of 80 to 95%.
(6) The urethane foam-reinforced reinforcing base fabric according to any one of (1) to (5) above, wherein the titanium oxide contained in the long fibers is 0.3 wt% or less.
(7) Using the urethane foam molding reinforcing base fabric described in (1) to (6) above, the urethane resin liquid is infiltrated into the base fabric and foamed to reinforce and integrate the polyurethane foam. Characteristic foam molded article.

The urethane foam molding reinforcing base fabric of the present invention is composed of a spunbonded nonwoven fabric made of crimped polypropylene long fibers, and the amount of titanium oxide fine particles added to the raw material is reduced for the purpose of whitening the fibers. However, the strength such as practical tear strength can be improved by using mild thermocompression bonding conditions.
Therefore, this is a urethane foam molding reinforcing cloth excellent in workability, which is excellent in bulkiness, excellent in tensile strength and tearing strength, has no problems such as breakage of the foamed molded product and perforation, etc. Furthermore, it is possible to produce an excellent urethane foam molded article having no cushioning property and no abnormal noise.

The present invention is described in detail below.
The urethane foam molding reinforcing base fabric of the present invention is a long fiber nonwoven fabric obtained by a spunbond method comprising crimped polypropylene long fibers.
As a first feature, the crimpable polypropylene long fiber used in the nonwoven fabric of the present invention is a bulky, coarsely structured nonwoven fabric composed of long fibers having 2 to 40 crimps / 25 mm, and has a pore volume. It is a nonwoven fabric with a high rate. Therefore, it is a non-woven fabric with high porosity, and the urethane resin can easily permeate, and after foaming, the adhesive can be satisfactorily bonded to the extent that the urethane foam and the reinforcing fabric are integrated.
As a second feature, by reducing the content of titanium oxide fine particles in the fiber, in the thermocompression treatment, the thermocompression bonding property between the fibers is improved, and by selecting mild thermocompression bonding conditions, The breaking elongation is improved, and as a result, the practical strength such as tear strength can be improved.
Therefore, even if the polyurethane foam molded product is in contact with a seat steel material such as a spring or a frame, the tearing property of the base fabric is good. Excellent durability such as frictional strength.

As the crimpable polypropylene-based long fiber of the present invention, it has a bulky property in which a urethane resin is soaked in a rough configuration, has excellent conformability to a mold, and is excellent in tensile strength, tear strength, etc. A fiber having a fiber diameter of 1 to 30 μm, preferably 3 to 25 μm, or a combination of a thin fiber diameter and a thick fiber diameter can be used, and the number of crimps is 2 to 40 times / 25 mm, preferably 5 to 35 times / 25 mm.
When the fiber diameter is less than 1 μm and the number of crimps is less than 2, a dense fiber structure is formed, and the resin penetration and strength are reduced. On the other hand, when the fiber diameter exceeds 30 μm, crimping is difficult and fiber dispersibility is lowered, and bulky fibers having a crimp number of more than 40 times / 25 mm are reduced in spreadability and are uniform in fiber dispersion. Problems such as lowering.

  The polypropylene fiber of the present invention is not particularly limited except that it has crimpability. For example, a fiber in which a resin such as polyethylene is mixed with polypropylene, a copolymer polypropylene fiber, a core-sheath type composite fiber in which the core is polyethylene and the sheath is polypropylene, a side-by-side type composite fiber, or the like is used.

Furthermore, as a configuration satisfying the bulky nonwoven fabric of the present invention, at least one layer is required to have a crimpable polypropylene fiber layer, but the other layer is a non-crimpable polypropylene fiber layer having a fiber diameter of 10 to 25 μm. A multilayer laminated structure with a fine fiber layer having a fiber diameter of 1 to 7 μm such as a melt blow method is used.
Specifically, a laminate of a crimpable polypropylene fiber layer having a fiber diameter of 15 to 30 μm and a non-crimpable polypropylene fiber layer having a fiber diameter of 10 to 25 μm, and a crimpable polypropylene fiber having a fiber diameter of 15 to 30 μm A multi-layered fiber layer of a non-crimped polypropylene fiber having a fiber diameter of 10 to 25 μm, an ultrafine fiber having a fiber diameter of 1 to 7 μm, and a non-crimped polypropylene fiber having a fiber diameter of 10 to 25 μm Is used.

Generally, in a thermoplastic synthetic fiber nonwoven fabric, inorganic fine particles such as titanium oxide are added as a matting agent in a raw material to whiten the fiber. However, the titanium oxide fine particles in the fiber have an action of reducing the adhesion due to thermocompression bonding between the fibers. The particle diameter of titanium oxide is preferably 0.1 to 1 μm, and more preferably 0.1 to 0.5 μm.
Therefore, as in the present application, in order to obtain a sufficient adhesive force by mild thermocompression bonding, it is preferable to reduce the amount of inorganic fine particles added. For example, the addition amount is 0.3 wt% or less, preferably 0.2 wt% or less, more preferably 0.1 wt% or less, and particularly preferably 0 wt%. If the added amount of inorganic fine particles exceeds 0.3 wt%, the adhesive strength between fibers decreases.
In the present invention, in particular, by reducing the content of titanium oxide in the crimped polypropylene long fiber, the fiber shape in the spinning process is suppressed in crystallinity, and the thermocompression bonding in the heat embossing process. It is possible to improve the thermocompression bonding conditions that are milder than usual. Specifically, the temperature, pressure, thermocompression rate, embossed area per piece, etc. can be reduced, and the integrity, form stability, and practical strength as a nonwoven fabric can be achieved without applying strong thermocompression bonding. Can have.

In the thermocompression bonding of the long-fiber web of the present invention, the embossed concavo-convex roll and the metallic smooth roll are bonded partially by softening or fusing under a specific temperature and pressure. The properties of the nonwoven fabric vary greatly depending on the thermocompression bonding conditions, for example, the size, spacing, depth, shape, etc. of each embossing roll protrusion.
Therefore, in order to obtain bulkiness and strength that satisfy the object of the present invention, it is necessary to limit the thermocompression bonding conditions to a specific range.
The roll temperature is 20 to 65 ° C. lower than the melting point (165 ° C.) of the polypropylene resin, preferably 35 to 55 ° C., and the thermocompression pressure is 10 to 700 kPa / cm, preferably 50 to 500 kPa / cm.
When the thermocompression bonding temperature is close to the melting point, the fibers are firmly bonded to each other by fusion, the fibers are fixed, and the tear strength is reduced.
Therefore, the fibers can be bonded to each other by crimping at a temperature 20 to 65 ° C. lower than the melting point, and even if a force such as tension is applied, no hole or the like is generated around the crimping portion. Further, by reducing the temperature and pressure, the bulkiness and tear strength can be kept high.

Next, the embossing pattern of the embossing roll is round, oval, rhombus, columnar, square, etc., and a uniform arrangement such as a parallel uniform arrangement or a staggered arrangement is preferable. Thermocompression bonded portions one of area, 0.3 to 10 mm ^2, preferably a 0.5 to 6 mm ^2, the depth of the embossed pattern is, 0.5 to 2 mm, preferably 0.7~1.7mm Yes, the thermocompression bonding interval is preferably 0.5 to 10 mm, preferably 0.8 to 6 mm.

  The area ratio of thermocompression bonding of the long-fiber nonwoven fabric of the present invention is preferably 3 to 30%, more preferably 5 to 25%, which keeps both tensile strength and tear strength high, and is bulky and flexible. For this purpose, the above-described thermocompression bonding area ratio is required. When the pressure-bonding area ratio is less than 3%, the bonding area decreases, and the tensile strength and wear strength decrease. On the other hand, if it exceeds 30%, the tensile strength and the wear strength increase, but the texture becomes paper-like, the tear strength decreases, and the compatibility with a mold or the like decreases.

The basis weight of the long-fiber nonwoven fabric of the present invention is 50 to 200 g / m ² , preferably 70 to 160 g / m ² .
When the basis weight is less than 50 g / m ² , the bulkiness is lowered, and the tensile strength and tear strength are lowered. On the other hand, when it exceeds 200 g / m ² , bulkiness, tensile strength, and tearing strength can be increased, but flexibility is lowered.

The pore volume ratio P of the long-fiber nonwoven fabric of the present invention is calculated from A: apparent specific gravity (weight per unit area) / 1000 (thickness) and B: specific gravity of fiber (polypropylene 0.91).
Pore volume ratio P = (B−A) / B × 100 (%)
The pore volume ratio P of the long fiber nonwoven fabric of the present invention is 80 to 95%, preferably 83 to 93%.
When the pore volume ratio P is less than 80%, a dense structure is obtained, there are few voids, and the integration of the urethane foam and the base fabric tends to be lowered, and the rigidity of the fiber is increased. Thus, flexibility is obtained but strength is reduced.

The long-fiber nonwoven fabric of the present invention is not firmly fixed to each other by thermocompression bonding, and is thermocompression bonded to such an extent that an appropriate tensile strength can be obtained, and has excellent elongation at break and high tear strength.
Therefore, the pendulum method tear strength per unit weight measured by JIS-L-1906 of the long fiber nonwoven fabric is 1.0 N or more, more preferably 1.2 N or more and 3.0 N or less.
If the tear strength converted to per unit weight is less than 1.0 N, it will be easy to cause a hole around the crimping part or tear due to the mounting tension of the mold or the like.

Regarding the tensile strength of the long-fiber nonwoven fabric of the present invention, the value obtained by converting the value in the (vertical + horizontal) direction by weight per unit area is 1 N / 5 cm or more, preferably 1.5 N / 5 cm or more and 5 N / 5 cm or less.
When the value obtained by converting the value in the (vertical + horizontal) direction is less than 1 N / 5 cm, the tensile strength of the fibers constituting the nonwoven fabric is weakly bonded to each other, and the fuzzing is liable to occur, resulting in poor handling.

  The urethane foam molding process using the reinforcing cloth of the present invention is performed by attaching a reinforcing cloth into a foam molding die, injecting a foamable urethane resin, and foaming polyurethane under heat and pressure, thereby forming a flexible polyurethane foam. To obtain a foamed molded article. Examples of the foaming method include a cold cold foaming method and a hot foaming method. What is required at the time of foam molding is that the urethane foam and the reinforcing cloth are bonded and integrated, and the urethane resin does not bleed out.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, it is not restrict | limited to the following Example.
〔Measuring method〕
1. Weight per unit (g / m ² )
According to the method specified in JIS-L1906, three test pieces measuring 20 cm × 25 cm in length are sampled per 1 m width of the sample, the mass is measured, and the average value is calculated by converting it into the mass per unit area.
2. Thickness (mm)
In accordance with the method defined in JIS-L1906, 10 points were measured in the width direction at a contact pressure load of 100 g / cm ² , and the average value was taken as the thickness. The thickness gauge is a PEACOCK NO. 207 was used.
3. Fiber diameter (μm)
Except for 10 cm at both ends of the sample such as fiber web and non-woven fabric, 1 cm square test pieces were cut out from the sections of every 20 cm width of the fabric to prepare samples. For each test piece, the fiber diameter was measured at 30 points with a microscope, and the average value of the measured values was calculated as the fiber diameter.
4). Tearing strength (N): Measured according to JIS-L-1906 pendulum method
Measure the vertical direction and convert the obtained value to unit weight 1g / m ²
Show.

5. Tensile strength (N / 5cm): Measured according to JIS-L-1906
The value obtained in the (vertical + horizontal) direction is set to a unit basis weight of 1 g / m ²
Shown in terms of conversion.
6). Pore volume fraction (%): Conforms to JIS-L-1096. (Polypropylene 0.91)
Apparent specific gravity A is weight per unit area (g / m ² ) / thickness (mm) × 1000
Pore volume ratio (%) = (fiber specific gravity−sample apparent specific gravity) / fiber specific gravity × 100

[Examples 1 to 3]
Using the spunbond method, titanium oxide in the raw material (polypropylene resin with a different particle size of 0.2 μm added) is used for melt spinning from a V-shaped profile cross-section nozzle, and cold air at a temperature of 60 ° C. is sent from the cooling device to the yarn. The crimp is expressed from the side surface of the sheet and stretched by a traction device to obtain a crimped continuous filament having an irregular cross section, and then the web is opened and collected on a conveyor net, and heated between a pair of concave and convex rolls. The thermocompression bonding conditions are such that the crimping part does not become a strong bond by fusion bonding, and the temperature is 125 ° C. to 145 ° C. (from the melting point of polypropylene resin (165 ° C.) to 20 to 40 ° C.) ℃ lower temperature), the pressure is 400 kPa / cm to 700 kPa / cm, and the embossed roll pattern has a diamond-shaped area of 1.8 mm ² , a depth of 1.2 mm, and a minimum interval of 3 Table 1 shows crimped polypropylene long fiber spunbond nonwoven fabrics of the present invention obtained by crimping in a staggered arrangement of 5 mm and partially thermocompressing the obtained web at a thermocompression rate of 12%.
Next, molding was performed using a two-component urethane resin in a foam molding apparatus. When the crimped polypropylene long fiber spunbonded nonwoven fabric was attached to the seat mold so as to conform to the concavo-convex portion, it was flexible and could conform to the shape of the mold. Subsequently, foam molding was performed by a cold molding method at 60 ° C. using a two-component urethane resin, and a urethane foam foam molding was obtained. The resulting molded body has resin penetration into the nonwoven fabric, good adhesion between the reinforcing fabric and the urethane resin, and no resin leakage, so there is no generation of scratching noises with springs, frames, etc. It was.

[Comparative Example 1]
A web was obtained in the same manner as in Example 1 except that the amount of titanium oxide added in the raw material was 1.0 wt%, and the thermocompression bonding conditions were performed so that the embossed portion was firmly bonded in the fused state. The obtained non-woven fabric had high tensile strength and rigidity, and the familiarity of the molding die was poor. Next, foam molding was performed, but a resin leak occurred from the thermocompression bonding peripheral part, and a rubbing sound of a spring, a frame, etc. was generated at the resin leak part, and the effect of the reinforcing cloth intended for the present application was not obtained. .
[Comparative Example 2]
A web was obtained in the same manner as in Example 1 except that the amount of titanium oxide added in the raw material was 1.0 wt%, and the thermocompression bonding conditions were mild. The characteristics of the obtained nonwoven fabric were that the resin leakage disappeared, but the adhesive strength of the thermocompression bonding part was insufficient, or the tear strength and tensile strength were low, and the intended strength of the present application was not obtained.

[Example 4]
Using the spunbond method, melt spinning is performed from a V-shaped profile cross-section spout using polypropylene resin with 0 wt% of the added amount of titanium oxide in the raw material, and cold air at a temperature of 60 ° C is blown from the side of the yarn from the cooling device. Crimp is developed and stretched by a traction device, and a crimped continuous filament having an irregular cross section, a web having a basis weight of 40 g / m ² (fiber diameter 25 μm, number of crimps 20/25 mm) is used as an upper layer, and an inorganic filler (oxidation) Using a polypropylene resin with an addition amount of titanium) of 0 wt%, melt spinning is performed from a round nozzle, and a laminated web is formed with a non-crimped continuous filament and a web having a basis weight of 40 g / m ² (fiber diameter 16 μm) as a lower layer. , Collected on a conveyor net, and thermocompression bonded between a pair of concave and convex rolls. The thermocompression bonding condition is mild, and the temperature is 130 ° C.
The pressure is 400 kPa / cm, the embossed roll pattern is crimped in a staggered arrangement with a diamond-shaped area of 2.5 mm ² , a depth of 1.0 mm, and a minimum spacing of 5.5 mm, and the resulting web is heated. Table 1 shows crimped polypropylene long fiber spunbonded nonwoven fabrics of the present invention obtained by partial thermocompression bonding at a compression rate of 8%.
Subsequently, foam molding was performed using a two-component urethane resin in a foam molding apparatus. When the crimped polypropylene long fiber spunbonded nonwoven fabric was attached to the seat mold so as to conform to the concavo-convex portion, it was flexible and could conform to the shape of the mold. Subsequently, foam molding was performed by a cold molding method at 60 ° C. using a two-component urethane resin, and a urethane foam foam molding was obtained. The resulting molded body has resin penetration into the nonwoven fabric, good adhesion between the reinforcing fabric and the urethane resin, and no resin leakage, so there is no generation of scratching noises with springs, frames, etc. It was.

  The reinforcing foam fabric for urethane foam molding of the present invention is excellent in bulkiness due to being made of crimped fibers, excellent in tensile strength and tearing strength, flexible, familiar to molds, etc., and excellent in workability. This is a urethane foam reinforcing fabric. The foamed molded product has no problems such as resin leakage, and does not break, perforate, etc. due to contact with steel materials for seats such as springs and frames, etc. Etc. does not occur. Therefore, it can be widely used for seats of vehicles and the like.

Claims (7)

A thermocompression bonding area ratio is 3% to 30%, one of the fused area of the thermocompression bonded portions is 0.3 to 10 mm ^2, the interval is 0.5 to 10 mm, polypropylene consisting crimped long fibers This is a reinforcing fabric composed of a spunbonded nonwoven fabric, the basis weight of the nonwoven fabric is 50 to 200 g / m ² , and the pendulum method tear strength per unit basis weight is 1.0 N or more as measured by JIS-L-1906 A reinforcing base fabric for urethane foam molding, characterized in that.   The reinforcing base fabric for urethane foam molding according to claim 1, wherein the number of crimps of the crimpable long fibers is 2 to 40 pieces / 25 mm.   The urethane foam-reinforced reinforcing base fabric according to claim 1 or 2, wherein the crimpable long fibers have a fiber diameter of 1 to 30 µm.   The reinforcing base fabric for urethane foam molding according to any one of claims 1 to 3, wherein the thermocompression bonding temperature is 100 to 145 ° C and the pressure is 10 to 700 kPa / cm.   The urethane foam reinforcing base fabric according to any one of claims 1 to 4, wherein the continuous fiber nonwoven fabric has a pore volume ratio of 80 to 95%.   The reinforcing base fabric for urethane foam molding according to any one of claims 1 to 5, wherein titanium oxide contained in the long fibers is 0.3 wt% or less.   A foamed molded article obtained by using the reinforcing foam fabric for urethane foam molding according to claim 1, infiltrating a urethane resin liquid into the base fabric, foaming, and reinforcing and integrating the polyurethane foam. .