JP2013075426A - Subsidiary material for flexible urethane mold foam, and method for manufacturing foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a subsidiary material for a flexible urethane mold foam which can discharge only gas from a mold die to outside and has excellent abnormal noise prevention performance without soaking of a raw material in venting through a vent hole, and to provide a method for manufacturing the subsidiary material for the flexible urethane mold foam.SOLUTION: The subsidiary material for the flexible urethane mold foam is used so that it is disposed to cover the vent hole the inside of an upper die of the mold die including the upper die and an lower die having the vent hole. The subsidiary material 4 for the flexible urethane mold foam includes a first sheet 7 into which vapor is penetrated but water is not permeated, and a second sheet 8 of water permeability which is attached to the first sheet 7.

Description

  The present invention relates to a secondary material for a flexible urethane mold foam used when manufacturing a cushion body used in automobiles, railway vehicles, furniture, and the like, and a method for manufacturing a flexible urethane mold foam.

  Conventionally, soft urethane mold foam having high cushioning properties has been used in various fields such as vehicle seats, headrests, and railcar seats. The cushion body made of the foam is obtained by discharging a foaming stock solution into a molding die, foaming and curing. By the way, the upper mold of the molding die is provided with a gas vent hole (vent hole) for discharging the reaction gas generated by the reaction of the foaming raw material in the foaming step to the outside of the molding die.

  However, the foaming raw material flows out of the vent hole at the same time as the gas is discharged, and there is a drawback that a lump of foaming raw material called a ball is formed and the number of steps for removing this lump increases. Therefore, conventionally, auxiliary materials are used in order to discharge only the gas from the vent holes and prevent the foaming raw material from flowing out (Patent Documents 1 and 2).

In Patent Document 1, a secondary material in which a non-breathable membrane is attached to the center of a breathable sheet is locked with a space between the mold and the non-breathable membrane, A technique is disclosed in which gas is discharged from a breathable sheet portion that is not in close contact, and the non-breathable membrane closes the vent hole after discharge.
Patent document 2 has a two-layer structure of a bulky nonwoven fabric and a dense nonwoven fabric, and discloses a technique for preventing impregnation of raw materials with the dense nonwoven fabric.

JP 2004-358910 A JP-A-6-171002

  However, in Patent Document 1, since there is a limit to the method of locking the secondary material, it cannot be used in a place where a space cannot be provided between the molds and a non-breathable membrane is attached to each vent. There is a problem that it is necessary to match the hole size. Therefore, there is a demand for a secondary material that is unsuitable for manufacturing various types of cushion bodies and that can handle any complex product.

Moreover, in the auxiliary material of patent document 1, since the part only of a breathable sheet exists, a raw material will impregnate a breathable sheet part. Accordingly, the breathable sheet portion impregnated with the raw material rubs against, for example, a metal spring member to generate abnormal noise, or the hardness of only the impregnated portion becomes hard. Furthermore, since the outgassing is not uniform in each product and the degree of impregnation is different, there is a problem that the formability and quality of the product vary.
On the other hand, in Patent Document 2, a dense nonwoven fabric is used, but impregnation is not completely prevented.

  The present invention has been made in consideration of the above, and it is possible to discharge only the gas from the inside of the molding die to the outside when venting the vent hole, and the soft urethane mold is excellent in preventing abnormal noise without being impregnated with the raw material. It aims at providing the manufacturing method of the auxiliary material for foams, and a flexible urethane mold foam.

  The auxiliary material for flexible urethane mold foam of the present invention is used by being disposed inside the upper mold of a molding mold having an upper mold having a vent hole and a lower mold so as to cover the vent hole. A secondary material for flexible urethane mold foam comprising: a first sheet that allows water vapor to pass but does not allow water to pass through; and a second sheet having water permeability that is bonded to the first sheet. And

  ADVANTAGE OF THE INVENTION According to this invention, while venting in a vent hole, only gas can be discharged | emitted from the inside of a shaping | molding die to the exterior, and the auxiliary material for flexible urethane mold foams excellent in noise prevention without being impregnated with a raw material is obtained. In addition, according to the present invention, a flexible urethane mold foam having good quality with no variation in physical properties of the product can be produced by integral foam molding using the auxiliary material.

Schematic of the molding die for manufacturing a flexible urethane mold foam using an auxiliary material. Explanatory drawing which expanded the principal part of FIG. 1 partially.

Hereinafter, the auxiliary material for flexible urethane mold foam according to the present invention and the method for producing the flexible urethane mold foam will be described.
In the present invention, the auxiliary material may be used by being disposed at least in the vicinity of the vent hole inside the upper mold and in the vicinity thereof, but may be disposed and used throughout the upper mold. As described above, the auxiliary material is a first sheet that allows water vapor to pass but does not allow water to pass (non-water-permeable), and a second sheet having water permeability that is bonded to the first sheet. It has.

Examples of the first sheet include a porous film made of polyethylene (trade name: KTF film manufactured by Mitsubishi Plastics, Inc.). Further, in the first sheet, “water impervious” means that the urethane foam stock solution does not pass other than normal water.
The second sheet is used to increase the strength of the auxiliary material, and may be anything as long as it has air permeability (does not block gas discharge) and water permeability. Examples of the second sheet include spunbonded nonwoven fabric (trade name: Elves manufactured by Unitika Ltd.), and felt may be used. In the second sheet, “water permeability” means that a urethane foam stock solution is passed in addition to normal water.

The air permeability of the auxiliary material is preferably 0.7 cc / cm ² / sec or less, more preferably 0.5 to 0.6 cc / cm ² / sec. The first sheet is provided with a large number of through holes penetrating vertically, and the average hole diameter of the through holes is preferably 0.05 to 0.12 μm, more preferably 0.08 to 0.10 μm. Here, if the average pore diameter is less than 0.05 μm, the air permeability is poor and it is difficult to remove the gas. On the other hand, if the average pore diameter exceeds 0.12 μm, the urethane foam undiluted solution passes through the first sheet and easily leaks out of the molding die. Air permeability is an important factor when the reaction gas generated by the reaction of the foaming raw material is discharged out of the molding die. When the air permeability of the auxiliary material and the numerical range of the diameter of the through hole are satisfied, the urethane foam raw material does not enter the first sheet, and only the gas can be discharged.
FIG. 1 is a schematic cross-sectional view of a case where a flexible urethane mold foam secondary material 4 is locked inside a top mold 1 of a molding mold 3 composed of an upper mold 1 and a lower mold 2 and integrally foamed. The figure is shown. 2 is an enlarged view of the main part of FIG. 1, FIG. 2 (A) is a partially enlarged cross-sectional view of the main part of FIG. 1, and FIG. 2 (B) is a lock of FIG. 2 (A). The side view of a pin part is shown.
The upper mold 1 is provided with a vent hole 5 for exhaust, and a plurality of locking pins 6 having flanges 6a are planted inside the upper mold 1 corresponding to the periphery of the vent hole 5. ing. The auxiliary material 4 is locked inside the upper mold 1 corresponding to the vent hole 5 and its periphery in a state of being stabbed by the locking pin 6. Here, as shown in FIG. 2, the auxiliary material 4 is composed of a porous film 7 as a first sheet and a non-woven fabric 8 as a second sheet bonded to the back surface of the porous film 7. ing. 1 and 2, reference numeral 9a denotes a female screw formed on the inner surface side of the upper mold 1, reference numeral 9b denotes a male screw of a locking pin 6 screwed to the female screw, and reference numeral 10 denotes a soft urethane mold that is foaming. Indicates a form. In FIG. 1, reference numeral 11 denotes a pipe for adjusting the temperature of the molding die 3 inserted into the upper die 1 and the lower die 2, and warm water flows through the pipe 11.

  However, in addition to locking the auxiliary material with the locking pin, a method of temporarily fixing with the spray paste can be used, and the auxiliary material can be performed without any particular limitation. In addition to arranging the secondary material inside the upper mold corresponding to the vent hole and its peripheral part, it may be attached to the entire inside of the upper mold, and the secondary material is attached to the vent hole and its peripheral part. This can be done in the same manner as in the case.

  In the present invention, the bonding of the first sheet and the second sheet can be performed by a known method such as thermal lamination, dry lamination, wet lamination, hot melt lamination, and extrusion lamination, and is not particularly limited. However, it is important to close the through hole of the first sheet and bond the first sheet so as not to impair the air permeability.

Next, specific examples and comparative examples of the present invention will be described.
Example 1
This will be described with reference to FIGS.
First, a spun pond non-woven fabric (trade name: Elves manufactured by Unitika Co., Ltd.) made of polyethylene terephthalate and polyethylene as the second sheet 8, and a porous film (made by Mitsubishi Plastics Co., Ltd.) made of polyethylene as the first sheet 7 (Trade name: KTF film) was bonded together by a hot melt laminating method to obtain a secondary material 4 for flexible urethane mold foam having a thickness of 0.16 mm. When the air permeability of the auxiliary material 4 was measured by the Frazier method, it was 0.59 cc / cm ² / sec even when the second sheet 8 was set on either the upper or lower side.

  Next, as shown in FIG. 2, the first sheet 4 is placed on the inner surface of the upper mold 1 on the inner side of the upper mold 1 and on the peripheral part including the vent hole 5 and its peripheral part. Then, the urethane foam stock solution was discharged into the lower mold 2, the upper mold 1 was closed, and the flexible urethane foam was integrally foamed to produce a flexible urethane mold foam. As a result, a good urethane mold foam having good quality in which gas escaped and the porous film was not impregnated with the urethane foam stock solution was obtained. Further, by arranging the first sheet 4 so as to be positioned inside the upper mold 1 and integrally foaming, the adhesive strength between the second sheet 8 facing the urethane foam stock solution side and the urethane foam stock solution can be increased. Can be raised.

(Comparative Example 1)
First, a dense non-woven sheet (made by DuPont, trade name: Tyvek) made of polyethylene having a breathability of 0.70 cc / cm ² / sec and a thickness of 0.15 mm was prepared as an auxiliary material. Next, as shown in FIG. 1, the auxiliary material was placed in the periphery of the upper mold 1 and including the vent hole 5, and then a flexible urethane mold foam was produced in the same manner as in Example 1. As a result, since the secondary material is not flexible, the followability to the upper mold 1 is poor, and the urethane foam undiluted solution wraps around between the secondary material and the upper mold 1, and the urethane foam is on the side in contact with the metal spring. It has been formed.

(Comparative Example 2)
First, as an auxiliary material, a melt-blown nonwoven fabric is sandwiched between two spunbonded nonwoven fabrics with air permeability of 27.0 cc / cm ² / sec and a thickness of 0.22 mm. (Trade name: PP-SMS) manufactured by the company was prepared. Subsequently, as shown in FIG. 1, the auxiliary material was disposed inside the upper mold 1 and in the peripheral portion including the vent hole 5, and then a flexible urethane mold foam was produced in the same manner as in Example 1. As a result, the urethane foam material was impregnated on the entire surface of the auxiliary material.

(Comparative Example 3)
First, as a secondary material, a secondary material (trade name: Borans, manufactured by Toyobo Co., Ltd.) having a breathability of 220 cc / cm ² / sec and a thickness of 1.2 mm was prepared. Next, as shown in FIG. 1, the auxiliary material was placed in the periphery of the upper mold 1 and including the vent hole 5, and then a flexible urethane mold foam was produced in the same manner as in Example 1. As a result, impregnation and outflow of the urethane foam raw material from the vent hole 5 were confirmed.

  Table 1 below shows the presence or absence of impregnation of raw materials, the presence or absence of outflow of raw materials, outgassing properties, moldability, and upper mold when producing flexible urethane mold foams according to Example 1 and Comparative Examples 1 to 3 above. The following property and the adhesiveness with the foaming raw material are compared.

  In Table 1 below, “presence / absence of impregnation of raw material” indicates whether or not the auxiliary material is impregnated with the urethane foam raw material. However, “None” in Example 1 means that the raw material is impregnated in the second sheet, but the raw material is not impregnated in the first sheet. In the comparative example, “none” means that the raw material is not impregnated into the auxiliary material having a single structure. In Comparative Examples 2 and 3, “Yes” means impregnation of the auxiliary material having a three-layer structure and the auxiliary material having a two-layer structure, respectively.

“Presence or absence of outflow of raw material” indicates whether or not the urethane foam raw material flows out of the upper mold through the auxiliary material. “Gas releasing property” indicates whether or not the reaction gas generated by the reaction of the urethane raw material escapes from the upper mold through the auxiliary material. “Formability” indicates whether or not defects such as lacking and voids have occurred in the product. “Followability to upper mold” indicates whether or not the auxiliary material follows the irregularities on the inner surface of the upper mold. “Adhesiveness with foaming raw material” indicates whether or not the secondary material adheres well to the urethane mold foam obtained when the foaming raw material is foamed.

  According to Table 1, in the case of Example 1, the presence or absence of the impregnation of the raw material, the presence or absence of the outflow of the raw material, the gas release property, the followability to the upper mold, and the adhesiveness with the foaming raw material are all good. It can confirm that it is excellent compared with Comparative Examples 1-3.

In the above embodiment, the case where a porous film is used as the first sheet and a spun pond nonwoven fabric is used as the second sheet is described, but the present invention is not limited to this, and water vapor passes through the first sheet. However, any material that does not allow water to pass therethrough may be used, and the second sheet may be any material that has water permeability. Moreover, in the said Example, although the case where air permeability was 0.59 cc / cm < ² > / sec was described, it is not restricted to this, The auxiliary material should just be 0.7 cc / cm < ² > / sec or less.

  DESCRIPTION OF SYMBOLS 1 ... Upper die, 2 ... Lower die, 3 ... Molding die, 4 ... Secondary material for soft urethane mold foam, 5 ... Vent hole, 6 ... Locking pin, 7 ... Porous film (1st sheet | seat) 8 ... Nonwoven fabric (second sheet), 9a ... female screw, 9b ... male screw, 10 ... soft urethane mold foam.

Claims (3)

In the auxiliary material for the flexible urethane mold foam used to be placed inside the upper mold of the molding mold having the upper mold and the lower mold with the vent hole so as to cover the vent hole,
A first sheet that allows water vapor to pass but not water;
A secondary material for flexible urethane mold foam, comprising: a second sheet having water permeability, which is bonded to the first sheet. Air permeability is 0.7 cc / cm < ² > / sec or less, The auxiliary material for flexible urethane mold foams of Claim 1 characterized by the above-mentioned. The step of disposing the auxiliary material for flexible urethane mold foam according to claim 1 or 2 so that the first sheet is located inside the upper mold and covers the vent hole;
A method for producing a flexible urethane mold foam, comprising: supplying a urethane foam stock solution into a lower mold, and then closing the upper mold and integrally foam-molding.

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