Mold and foam manufacturing method

Abstract

To provide: a molding die capable of reducing penetration into ventilation members, collapse of cells in a flexible foam, and occurrence of lack of a thickness in the flexible foam when a raw material liquid of the flexible foam reacts and foams; and a manufacturing method for a foam body composed of the flexible foam.SOLUTION: A molding die comprises: a gas vent hole passing through the molding die in a thickness direction; and a ventilation member closing the gas vent hole. The ventilation member includes: an air permeability measured at a pressure of 125 Pa is 0.05 cm3 / cm2 s or more and 1.2 cm3 / cm2 s or less; and an air permeability measured at a pressure of 1 kPa is 0.2 cm3 / cm2 s or more and 2.4 cm3 / cm2 s or less, in accordance with an A method specified in JIS L1096:2010.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mold and a method for producing a foam. [Background technology]

[0002] There is a technology in which a mold for molding a foamed body made of a soft foam is provided with a gas vent hole, a ventilation member is placed in the gas vent hole, and gas generated during molding and air in the cavity are discharged from the gas vent hole through the ventilation member (Patent Document 1). In the technology disclosed in Patent Document 1, the ventilation member has an air permeability of 0.7 cm 3 / cm 2 ·s or less. This is to prevent gas and air from escaping suddenly during molding, and to prevent the soft urethane foam from penetrating the ventilation material and the foam bubbles from collapsing. The breathability is a value measured at a pressure of 125 Pa in accordance with Method A specified in JIS L1096:2010. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-75426 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the prior art, if the breathability is low, the gas remaining in the cavity may cause the material to not reach the corners or parting line of the mold, resulting in chipping at the edges of the foam (hereinafter referred to as "underfill"), or the material may fill the corners or parting line of the mold first, resulting in underfill near the center of the foam, or the bubbles in the foam may be crushed and collapsed.

[0005] The present invention has been made to solve this problem, and has an object to provide a molding die and a method for manufacturing a foam that can reduce the intrusion of soft foam into the ventilation member, the collapse of bubbles in the foam, and the occurrence of underfill. [Means for solving the problem]

[0006] To achieve this object, the mold of the present invention is provided with a gas vent hole penetrating the mold in the thickness direction and a ventilation member that closes the gas vent hole. The ventilation member has an air permeability of 0.05 cm when measured at a pressure of 125 Pa in accordance with the A method specified in JIS L1096:2010. 3 / cm 2 ·s or more 1.2cm 3 / cm 2 s or less, and the air permeability measured at a pressure of 1 kPa is 0.2 cm 3 / cm 2 ·s or more 2.4cm 3 / cm 2 ·s or less.

[0007] The method for producing a foam of the present invention includes a molding step of foaming a raw material liquid of a flexible foam in a cavity formed by a molding die to form a foam, and a demolding step of releasing the foam from the molding die. The ventilation member that closes the gas vent hole penetrating the molding die in the thickness direction has an air permeability of 0.05 cm when measured at a pressure of 125 Pa in accordance with Method A specified in JIS L1096:2010. 3 / cm 2 ·s or more 1.2cm 3 / cm 2 s or less, and the air permeability measured at a pressure of 1 kPa is 0.2 cm 3 / cm 2 ·s or more 2.4cm 3 / cm 2 s or less. Effect of the Invention

[0008] According to the mold of claim 1, the ventilation member has an air permeability of 0.05 cm when measured at a pressure of 125 Pa in accordance with the A method defined in JIS L1096:2010. 3 / cm 2 ·s or more 1.2cm 3 / cm 2 s or less, and the air permeability measured at a pressure of 1 kPa is 0.2 cm 3 / cm 2·s or more 2.4cm 3 / cm 2 ·s or less. As a result, the higher the pressure inside the mold, the more gas passes through the ventilation member, and even when the pressure inside the mold drops, the gas passes through the ventilation member little by little. Because an appropriate amount of gas passes through the ventilation member whether the pressure inside the mold is high or low, it is possible to reduce the intrusion of the soft foam into the ventilation member, the underfill of the foam, and the collapse of the bubbles.

[0009] moreover The ventilation member is fixed to the mold after the foam is released from the mold. Teto The air element can be reused.

[0010] Claim 2 According to the method for producing the foam described above, the ventilation member has an air permeability of 0.05 cm2 measured at a pressure of 125 Pa in accordance with the A method defined in JIS L1096:2010. 3 / cm 2 ·s or more 1.2cm 3 / cm 2 s or less, and the air permeability measured at a pressure of 1 kPa is 0.2 cm 3 / cm 2 ·s or more 2.4cm 3 / cm 2 Therefore, it has the same effect as claim 1. 。 [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view of a molding die according to one embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a foam molded using a mold. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a cross-sectional view of a mold 10 in one embodiment. Fig. 2 is a cross-sectional view of a foam 40 molded using the mold 10. In Fig. 1, part of the mold 10 is omitted, and the thickness of a ventilation member 20 (described later) is greatly emphasized.

[0013] As shown in Fig. 1, the molding die 10 is made of metal or synthetic resin and is selected depending on the material of the flexible foam. The molding die 10 has a first die 11, which is an upper die, and a second die 12, which is a lower die, closed to form a cavity 13 between a cavity surface 15 of the first die 11 and a cavity surface 16 of the second die 12. A raw material liquid for the flexible foam is mixed and foamed in the cavity 13 to form a foam 40.

[0014] The mold 10 is provided with a gas vent hole 14 penetrating the mold 10. In this embodiment, the gas vent hole 14 penetrates from the outer surface 17 opposite the cavity surface 15 of the first mold 11 to the cavity surface 15. The cross-sectional area of ​​the gas vent hole 14 near the opening 14a that opens into the cavity surface 15 is smaller than the cross-sectional area near the outer surface 17. The shape of the gas vent hole 14 is not limited to this, and the cross-sectional area near the opening 14a and the cross-sectional area near the outer surface 17 may be approximately equal. The diameter of the gas vent hole 14 at the portion with the smallest cross-sectional area is, for example, 1-5 mm, more preferably 1-3 mm.

[0015] The molding die 10 is provided with a ventilation member 20 that closes the gas vent hole 14. In this embodiment, the ventilation member 20 includes, in order from the outer surface 17 side toward the cavity 13 side, a first layer 21 and a second layer 22. Examples of materials for the first layer 21 and the second layer 22 include sheets such as nonwoven fabric, paper, felt, and synthetic resin, films, and combinations of these.

[0016] In this embodiment, the first layer 21 and the second layer 22 are bonded to each other. An adhesive layer 23 is provided on the surface of the first layer 21 opposite to the surface to which the second layer 22 is bonded. The ventilation member 20 is fixed to the cavity surface 15 by the adhesive layer 23, and covers the entire openings 14a of the gas vent holes 14.

[0017] The ventilation member 20 has a permeability (hereinafter referred to as "first permeability") of 0.05 cm or less as measured at a pressure of 125 Pa in accordance with the A method (Fragile method) specified in JIS L1096:2010. 3 / cm 2 ·s or more 1.2cm 3 / cm 2 s or less. JIS L1096:2010 specifies that the average value of five air permeability measurements should be rounded off to the first decimal place, but in this embodiment, when the average value of the five measurements is less than 0.1, the average value is rounded off to the third decimal place.

[0018] The ventilation member 20 has a breathability (hereinafter referred to as the "second breathability") of 0.2 cm when measured at a pressure of 1 kPa instead of the pressure of 125 Pa according to the A method defined in JIS L1096:2010. 3 / cm 2 ·s or more 2.4cm 3 / cm 2 ·s or less. The air permeability is the air permeability of the entire ventilation member 20 including the first layer 21, the second layer 22, and the adhesive layer 23. In this embodiment, the first air permeability and the second air permeability of the first layer 21 are smaller than the first air permeability and the second air permeability of the second layer 22.

[0019] The foam 40 is made of soft polyurethane foam. A surface 41 of the foam 40 is formed by the cavity surface 16 of the second mold 12. A back surface 42 of the foam 40 is formed by the cavity surface 15 of the first mold 11. A back surface material 30 is disposed on the back surface 42. The material of the back surface material 30 is, for example, a nonwoven fabric.

[0020] The manufacturing method of the foam 40 will be described. First, the first mold 11 is opened, and the backing material 30 is attached to the cavity surface 15. Next, in the molding process, a raw material liquid containing liquid A, in which polyols, crosslinking agents, foam stabilizers, foaming agents, and catalysts are premixed, and liquid B, which is polyisocyanates, is supplied to the second mold 12, and then the first mold 11 is closed. The raw material liquid reacts in the cavity 13 to generate reactants and generate carbon dioxide gas. The volume increases due to the competitive reactions of resinification and gasification. As the volume of the reactants increases, the space in the cavity 13 gradually narrows. Carbon dioxide gas generated by the reaction and air in the cavity 13 (hereinafter, carbon dioxide gas and air are referred to as "gas") are discharged to the outside of the molding die 10 through the gas vent hole 14 through the ventilation member 20 as the reactants expand. Since the increase in the volume of the reactants per unit time is greater than the amount of gas passing through the gas vent hole 14 per unit time, the pressure in the space in the cavity 13 gradually increases.

[0021] The ventilation member 20 that closes the gas vent hole 14 has a first air permeability of 0.05 cm 3 / cm 2 ·s or more 1.2cm 3 / cm 2 ·s or less, and the second breathability is 0.2cm 3 / cm 2 ·s or more 2.4cm 3 / cm 2 ·s or less, it is possible to prevent the gas in the cavity 13 from suddenly escaping through the gas vent hole 14. This makes it possible to prevent the reactants from entering the ventilation member 20 and the bubbles (cells) of the foam 40 from collapsing.

[0022] The higher the pressure in the cavity 13, the more gas passes through the ventilation member 20. The ventilation member 20 can prevent the pressure in the cavity 13 from becoming so high that the reactants do not reach the corners or parting line of the mold 10 or reach the corners or parting line of the mold 10 first, so that the reactants spread to the cavity surfaces 15, 16. This reduces the occurrence of underfill in the foam 40. Furthermore, it reduces the occurrence of cell collapse caused by the bubbles (cells) of the foam 40 being crushed. It also reduces burrs that occur in the foam 40 due to the reactants penetrating the parting surface between the first mold 11 and the second mold 12.

[0023] Even if a large amount of the gas in the cavity 13 passes through the ventilation member 20 and the pressure in the cavity 13 decreases, the gas in the cavity 13 passes through the ventilation member 20 little by little and is discharged to the outside of the molding die 10. When the reactants reach the cavity surface 15, some of the reactants penetrate between the fibers of the backing material 30 and harden as they are, integrating the backing material 30 and the flexible foam. Because the backing material 30 is interposed between the flexible foam (the reactants) and the ventilation member 20, it becomes difficult for the flexible foam to penetrate the ventilation member 20.

[0024] The gas in the cavity 13 passes through the second layer 22 of the ventilation member 20, and then through the first layer 21. The reactants that have entered the back surface material 30 reach the second layer 22, which has high breathability, before reaching the first layer 21, which has low breathability. Since the reactants and release agent are less likely to reach the first layer 21, the reactants and release agent are less likely to clog the pores of the first layer 21, which has lower breathability than the second layer 22. This makes it easier to maintain the breathability of the first layer 21.

[0025] Next, in a demolding step, the mold 10 is opened and the foam 40 is removed from the mold 10. The backing material 30 is integrated with the foam 40 as a part of the foam 40. The ventilation member 20 is fixed to the cavity surface 15 by the adhesive layer 23. Therefore, when the foam 40 is repeatedly molded using the mold 10, the ventilation member 20 can be used as it is. As a result, the work of arranging the ventilation member 20 in the mold 10 can be reduced. EXAMPLES

[0026] The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0027] A test was conducted to manufacture foams using molds No. 1-7, which differ in the air permeability of the ventilation member and the diameter (hole size) of the smallest cross-sectional area of ​​the gas vent hole. Air permeability was measured five times at a pressure of 125 Pa (first air permeability) and at a pressure of 1 kPa (second air permeability) in accordance with Method A of JIS L1096:2010, and the average value of the five measurements was rounded off to the nearest tenth. However, when the average value of the five measurements was less than 0.1, the average value was rounded off to the nearest tenth.

[0028] The raw material liquid for flexible polyurethane foam was supplied to molds No. 1-7, and the moldability of the foam produced by the reaction of the raw material liquid and the penetration of the reactants of the raw material liquid into the ventilation members were evaluated. All the dimensions of molds No. 1-7 were constant except for the diameter of the gas vent holes, and the thickness of the ventilation members was constant. The material and amount of the raw material liquid, and the temperature of the molds during the test were also constant.

[0029] Moldability was rated as A when there was no underfill or cell collapse in the foam, and C when either underfill or cell collapse occurred in the foam. Reactant penetration was rated as A when no reactants penetrated into the ventilation member at all, B when reactants penetrated the surface of the ventilation member (the surface in contact with the cavity) but did not reach the back surface of the ventilation member, and C when reactants reached the back surface of the ventilation member. The results are shown in Table 1.

[0030] [Table 1] As shown in Table 1, mold No. 1-5 was rated A in moldability, but mold No. 6 was rated C because of underfilling of the foam. 3 / cm 2 ·s or more 1.2cm 3 / cm 2·s or less, and the second breathability is 0.2cm 3 / cm 2 ·s or more 2.4cm 3 / cm 2 Although the conditions below are met, the air permeability of No. 6 was lower than that of No. 1-5 in both the first and second air permeability, and did not meet these conditions. It is presumed that the internal pressure of the mold for No. 6 was high, which prevented the reactants from reaching the corners and parting line of the mold, resulting in underfill in the foam.

[0031] In terms of the infiltration of reactants, mold No. 1-5 were rated A or B, while mold No. 7 was rated C. The first air permeability of mold No. 7 was 0.05 cm 3 / cm 2 ·s or more 1.2cm 3 / cm 2 Although the condition below was met, the second permeability was higher than that of No. 1-5, so the condition was not met. Since the flow rate of gas passing through the ventilation member of No. 7 was high, it is presumed that the reactants entered the ventilation member.

[0032] In particular, the infiltration of reactants into the ventilation member of mold No. 1-4 was rated A. Therefore, a gas vent hole diameter of 3 mm or less was suitable. It became clear that the ventilation member of mold No. 1-4 can be repeatedly used when producing foams.

[0033] The present invention has been described above based on the embodiments and examples, but the present invention is not limited to these in any way, and it can be easily imagined that various improvements and modifications are possible within the scope of the present invention without departing from the spirit and scope of the present invention.

[0034] In the embodiment, a case has been described in which one gas vent hole 14 is provided in molding die 10, but this is not necessarily limited to this. It is of course possible to provide a plurality of gas vent holes 14 in molding die 10. The plurality of gas vent holes 14 may be of the same size or different sizes.

[0035] In the embodiment, the molding die 10 is composed of the first die 11 and the second die 12, but the present invention is not limited to this. It is of course possible to provide a core die in addition to the first die 11 and the second die 12.

[0036] In the embodiment, the case where the back surface material 30 is disposed on the first mold 11 and integrated with the foam 40 has been described, but the present invention is not necessarily limited to this. Naturally, the back surface material 30 can be omitted.

[0037] In the embodiment, the gas vent hole 14 is provided in the first die 11, but this is not necessarily limited to this. It is of course possible to provide the gas vent hole 14 in the second die 12, or to provide the gas vent hole 14 in both the first die 11 and the second die 12.

[0038] In the embodiment, the ventilation member 20 is disposed on the surface of the molding die 10 that contacts the cavity 13, but this is not necessarily limited to this. It is of course possible to dispose the ventilation member 20 on the outer surface 17 of the molding die 10 or inside the gas vent hole 14.

[0039] In the embodiment, the ventilation member 20 including the first layer 21 and the second layer 22 has been described, but is not necessarily limited to this. It is of course possible to make the ventilation member 20 consisting of a single layer or three or more layers. In a ventilation member including multiple layers, the layers do not necessarily have to be bonded together.

[0040] In the embodiment, the case where the ventilation member 20 is adhered to the molding die 10 has been described, but this is not necessarily limited to this. It is of course possible to fix the ventilation member 20 to the molding die 10 by means other than adhesion. An example of a means other than adhesion is fixing the ventilation member 20 to the molding die 10 by fastening or clamping it with a fastener. [Explanation of symbols]

[0041] 10 mold 13 Cavity 14 Gas vent hole 20 Ventilation material 40 Foam

Claims

1. A mold for molding a foamed product made of a flexible foam, a gas vent hole penetrating the molding die in a thickness direction, and a ventilation member closing the gas vent hole, The ventilation member has an air permeability of 0.05 cm when measured at a pressure of 125 Pa in accordance with the A method defined in JIS L1096:2010. ３ / cm ２ ・S or more 1.2cm ３ / cm ２ s or less, and the air permeability measured at a pressure of 1 kPa is 0.2 cm ３ / cm ２ ・S or more 2.4cm ３ / cm ２ A molding die having a foaming rate of s or less, the foam being fixed to the molding die when the foam molded with the molding die is released from the die.

2. A method for producing a foam using a mold for molding a foam made of a flexible foam, comprising the steps of: a gas vent hole penetrating the molding die in a thickness direction, and a ventilation member closing the gas vent hole, a molding step of foaming the raw material liquid of the flexible foam in a cavity formed by the molding die to form the foam; A demolding step of releasing the foam from the mold, The ventilation member has an air permeability of 0.05 cm when measured at a pressure of 125 Pa in accordance with the A method defined in JIS L1096:2010. ３ / cm ２ ・S or more 1.2cm ３ / cm ２ s or less, and the air permeability measured at a pressure of 1 kPa is 0.2 cm ３ / cm ２ ・S or more 2.4cm ３ / cm ２ s or less, and the foam is fixed to the mold even after the demolding step.

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