JP2006264225A - Shaping mold for urethane and surface treating method of shaping mold for urethane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaping mold for urethane maintaining high mold releasability for a long term. <P>SOLUTION: The shaping mold 1 for urethane comprises a plated layer 4 containing at least one of nickel, chrom and zinc and a fluorine resin layer 6 provided on the plated layer 4, the fluorine resin layer being impregnated into the plated layer 4, on a shaping surface of a mold 2. The plated layer 4 gives the shaping surface of the mold 2 hardness big enough for the shaping surface not to be damaged by shaping and cleaning. Since the fluorine resin layer 6 is impregnated into the plated layer 4 and is firmly fixed in the plated layer 4, a crack or a peel hardly occurs. Accordingly the shaping surface of the mold 1 for urethane maintains high mold releasability due to the fluorine resin layer 6 for a long term. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a urethane mold used in the manufacture of vehicle seat pads and the like, preferably a mold suitable for urethane foam molding, and a surface treatment method for such a mold.

  A seat pad of a vehicle seat can be manufactured by foaming polyurethane foam. Conventionally, in such a manufacturing process, in order to prevent the obtained urethane molded product from sticking to the surface of the mold, a urethane-based release agent is spray-coated on the surface of the mold and dried, and then the urethane raw material is used. It is injected and molded. However, a mold release agent must be applied at each molding, and it must be cleaned frequently to prevent unevenness on the molding surface due to the remaining mold release agent and variations in mold temperature. It is not efficient because it requires complicated actions such as

As a method for improving the releasability without using a release agent, a method of coating the surface of such a mold with a fluororesin has been proposed (for example, see Patent Document 1). However, since the fluororesin coating is generally soft, it cannot withstand the use situation of repeated use and frequent cleaning as in industrial production. Therefore, as a mold that secures the hardness of the surface and does not require a mold release agent, the surface of the mold is used in Patent Document 2 using a plating solution of nickel and phosphorus in which particles of tetrafluoroethylene resin are suspended. The one plated with is disclosed.
Japanese Utility Model Publication No. 57-183137 JP 9-183129 A

  However, with this method, the amount of the tetrafluoroethylene resin that can be suspended in the plating solution is limited, and the desired release performance cannot always be obtained. Moreover, since the plating layer, that is, nickel and phosphorus are exposed and these have binding properties to urethane, it is difficult to obtain release properties equivalent to those when a release agent is applied.

Therefore, an object of the present invention is to provide a urethane mold that maintains a higher mold release performance over a long period of time.
In addition, another object of the present invention is to provide a surface treatment method for a molding die for urethane capable of forming a mold surface that maintains a higher mold release performance over a long period of time.

As a means for solving the above-mentioned problems, the first invention of the present invention is a plating layer containing at least one of nickel, chromium, and zinc on a molding surface of a mold, and plated in a state where the plating layer is impregnated. Provided is a urethane mold comprising a fluororesin layer provided on a layer.
In this mold, the plating layer imparts hardness to the mold surface so as not to be damaged during molding or cleaning. Further, since the fluororesin layer is provided in a state of being impregnated in the plating layer, it is well fixed to the plating layer, and cracks and peeling are not likely to occur. Therefore, good releasability by the fluororesin layer on the molding surface is kept longer.

  In a preferred embodiment of the molding die, the plating layer is thicker than 10 μm, and the surface treatment layer including the plating layer and the fluororesin layer is 15 μm or more. Such a mold exhibits good releasability in urethane foam molding, particularly molding urethane foam suitable for a seat pad such as a vehicle seat, and is not easily damaged and has good durability.

  Furthermore, in a preferable embodiment of the mold, the thickness from the surface of the plating layer to the surface of the fluororesin layer is 5 μm or more. Such a mold has better releasability.

  Further, the second invention of the present invention is a surface treatment method of a molding die for urethane, wherein the fluororesin particles are dispersed on the molding surface provided with a plating layer containing at least one of nickel, chromium and zinc. There is provided a surface treatment method for a molding die for urethane, comprising a dipping step of dipping in a fluororesin dispersion held in step 1 and a baking step of drying the molding surface after the dipping step at a high temperature.

  Further, in a preferred embodiment of the surface treatment method, a molding surface including a fluororesin layer impregnated in a plating layer through the baking step is immersed in a fluororesin dispersion in which fluororesin particles are held in a dispersed state, and after the immersion The fluororesin layer thickening step of drying the molding surface at a high temperature is performed once or more.

  In this method, a fine surface formed by irregularities on the porous surface is formed by immersing a molding surface, which is provided with a plating layer with a hardness that is not easily damaged and a porous surface that is easily impregnated with a fluororesin, in a fluororesin dispersion. The pores can be filled with the fluororesin layer and the molding surface can be uniformly applied with the fluororesin. After that, by drying at high temperature, the fluororesin is fixed on the surface of the plating layer in a state of being impregnated in the pores of the plating layer. Therefore, the surface of the plating layer can be stabilized by the three-dimensional structure of the fluororesin itself. . Therefore, according to this surface treatment method, it is possible to obtain a molding die in which a good mold release property is more stably imparted to the molding surface. In addition, by having the fluororesin layer thickening step one or more times, the fluororesin layer can be laminated uniformly and in a desired thickness, and the releasability and durability can be improved.

  According to the present invention, there is provided a urethane molding die in which higher mold release performance is maintained for a long time, and a surface treatment method for a urethane molding die capable of forming a mold surface in which higher mold release performance is maintained for a long time. By providing, it is possible to efficiently produce a urethane molded product by reducing molding defects due to releasability.

  The urethane mold according to the present invention can be applied to various molds for producing polyurethane molded products. It is a shaping | molding die provided with the structure which concerns on this invention in at least one part of the part which shape | molds urethane of the shaping | molding die for urethanes, Preferably the whole molding surface which contacts urethane has the structure which concerns on this invention. In the mold | die divided | segmented into 2 or more, at least 1 is a shaping | molding die for urethane which is a shaping | molding die provided with the said conditions. Preferably, a polyurethane foam molded article, for example, a foam molding die for various pad members including a seat pad for a vehicle seat is used. Typically, the mold includes a pair of molding surfaces, and the plating layer and the fluororesin layer are provided on either one or both of the pair of molding surfaces.

  First, an embodiment of a mold according to the present invention will be described. In FIG. 1, sectional drawing of the molding surface of the shaping | molding die for urethane which concerns on one Embodiment of this invention is shown. The mold 1 includes a mold 2, a plating layer 4 that coats the molding surface of the mold 2, and a fluororesin layer 6 that covers the plating layer 4. The mold 2 can be a known mold formed of a conventionally known metal material, for example, iron, aluminum, stainless steel or the like. Typically, an aluminum mold is suitable as the mold for the seat pad.

  The plating layer 4 is plating formed by a known plating process, and includes at least one of nickel, chromium, and zinc as its component. Specifically, for example, nickel plating, electroless nickel plating, hard chrome plating, zinc plating and the like. Although the thickness of the plating layer 4 is not limited, in the case of a urethane foam molded product for a seat pad, for example, when the thickness exceeds 10 μm, the filling amount of the fluororesin on the surface of the plating layer becomes appropriate. The releasability is good, which is preferable. More preferably, the thickness of the plating layer 4 is 15 μm or more. For example, when the thickness is 40 μm, good hardness and releasability can be obtained in a urethane mold for a seat pad, and the fluororesin layer 6 has good scratch resistance. Adhesiveness can be imparted.

  The fluororesin layer 6 is a film made of a fluororesin that is excellent in known releasability. The fluororesin constituting the fluororesin layer 6 is typically polytetrafluoroethylene (PTFE), and can be appropriately made of a PTFE copolymer. Examples of the PTFE copolymer include a tetrafluoroethylene hexafluoropropylene copolymer, a tetrafluoroethylene perfluoropropyl vinyl ether copolymer, and an ethylene tetrafluoroethylene polymer. These fluororesins are generally stable at high temperatures and have good releasability with respect to urethane. Although not shown, the fluororesin layer 6 penetrates or impregnates the irregularities on the surface of the plating layer 4, and is provided in a layered manner with a predetermined thickness on the upper surface of the plating layer 4. That is, the surface of the plating layer 4 obtained by a known plating process is a porous surface, but is in close contact with the porous surface and filled in the holes. The thickness of the fluororesin layer 6 from the upper surface of the plating layer 4 of the fluororesin layer 6 is not limited. However, for example, when the thickness is 5 μm or more, the release property of urethane, particularly foamed urethane, is improved. Can be preferred.

  The sum of the thickness of the plating layer 4 and the thickness of the fluororesin layer 6 is at least 15 μm or more, and at least the plating layer 4 preferably has a thickness exceeding 10 μm. In this case, good release properties can be secured by the fluororesin layer 6, good hardness can be imparted by the plating layer 4, and the scratch resistance of the fluororesin layer 6 can be improved satisfactorily. Preferably, the sum of the thickness of the plating layer 4 and the thickness of the fluororesin layer 6 is 45 μm or more, and the thickness of the plating layer 4 is 40 μm or more. The urethane molding die 1 satisfying this condition makes it possible to maintain an excellent release property for a longer period of time, particularly in the case of urethane foam molding of a vehicle seat pad, and to manufacture an efficient seat pad.

  The molding surface of the urethane mold 1 is given hardness by the plating layer 4 and good release properties by the fluororesin layer 6. The fluororesin layer 6 is impregnated on the porous surface of the plating layer 4, has a large contact area with the plating layer 4, and is fixed three-dimensionally. For this reason, compared with the case where the fluororesin layer 6 is directly provided on the mold 2, the adhesion strength between the plating layer 4 and the fluororesin layer 6 is high, and the problem is that the fluororesin layer 6 is soft. The cracks that were formed are difficult to form. As a result, good releasability is stably maintained over a long period. Therefore, the urethane mold 1 can maintain not only repeated molding but also good scratch resistance that can withstand friction when cleaning a urethane basket using a metal tool or the like. For this reason, it is possible to provide a mold that can repeatedly perform urethane molding, particularly urethane foam molding, without using a release agent.

  In the urethane mold 1, since the thickness and type of the plating layer 4 are set independently, desired hardness and the like can be imparted to the molding surface. Moreover, since the fluororesin layer 6 is a film formed with a thickness set independently, it can be laminated so as to have desired release properties and wear resistance. Therefore, it can be set as a shaping | molding die provided with the shaping | molding surface provided with preferable hardness, mold release property, and damage resistance according to the property of urethane.

Next, an embodiment of a surface treatment method for obtaining the urethane mold 1 will be described.
The molding surface of the mold 2 is appropriately subjected to known pretreatments such as polishing, degreasing, and acid treatment. Next, the molding surface of the mold 2 is plated by a known method using a plating solution containing at least one of nickel, chromium, or zinc. At this time, it is preferable that the thickness of the plating layer 4 exceeds 10 μm, and more preferably 40 μm or more.

  After laminating the plating layer 4 on the mold 2, an immersion process is performed. In the dipping process, at least a part of the molding surface on which the plating layer 4 of the mold 2 is laminated is dipped in a fluororesin dispersion containing a fluororesin in a dispersed state. Here, the fluororesin dispersion is a dispersion such as an emulsion or a dispersion in which the above-described fluororesin is dispersed or suspended in the form of particles. Such dispersions are known and can be prepared by known methods. As a dispersion medium of the dispersion, known organic solvents such as water, alcohols such as isopropanol, ethers such as dimethyl ether, hydrocarbons such as dichloromethane, paraffins, and the like may be used. By immersing the molding surface provided with the plating layer 4 in the fluororesin dispersion, the fluororesin dispersion is attached to the inside of the irregularities of the plating layer 4 and the upper surface of the plating layer 4 with a uniform thickness.

  After the dipping process, a baking process is performed. In the baking process, the surface of the mold 2 on which the fluororesin dispersion is adhered is dried at a high temperature. The temperature in the high temperature drying is a temperature at which the dispersion medium evaporates and the fluororesin forms a coating film, and is, for example, 200 ° C. or more and 300 ° C. or less. By high-temperature drying, the fluororesin can be fixed on the plated layer 4, that is, baked. Thereby, the fluororesin layer 6 can be formed on the molding surface.

  The thickness of the fluororesin layer 6 obtained by the dipping process is limited by characteristics such as the viscosity of the fluororesin dispersion. For example, a thicker fluororesin layer can be formed by increasing the concentration (solid content) of the fluororesin in the fluororesin dispersion. Moreover, in order to obtain the fluororesin layer 6 having a larger thickness, a fluororesin thickening process can be performed after the baking process. The fluororesin thickening step includes a step of immersing a molding surface provided with the fluororesin layer obtained by the baking step in a fluororesin dispersion in which fluororesin particles are held in a dispersed state, and drying the molded surface after immersion at a high temperature. . Moreover, the process of immersing the surface of a fluororesin layer in a fluororesin dispersion liquid, and drying at high temperature is repeated one or more times suitably after this process. The fluororesin dispersion used in the fluororesin thickening process is the same as that in the immersion process, and the conditions of the baking process are also the same. Typically, when performing the fluororesin thickening step, the same fluororesin dispersion as that used before is used, but different fluororesin dispersions such as the concentration and the type of fluororesin may be used. Similarly, the drying conditions such as the drying temperature in the high temperature drying may be the same as or different from those in the baking step.

In this surface treatment method, the molding surface on which the plating layer 4 is laminated is immersed in a fluororesin dispersion, so that the fluororesin can easily enter the pores of the plating layer 4, that is, formed by irregularities on the porous surface. The pores can be impregnated with a fluororesin. Further, the fluororesin can be applied with a uniform thickness on the upper surface of the plating layer 4. Therefore, the fluororesin layer 6 obtained through the baking step has a more uniform thickness and is more uniformly adhered to the plating layer 4 and has uniform strength and scratch resistance. In addition, the plating treatment can be performed so that various thicknesses of plating can be obtained by various methods regardless of the formation of the fluororesin layer 6, and therefore, plating having various surface hardness and surface roughness is performed. Can do. Moreover, the fluororesin layer 6 can also be formed in a desired thickness by performing the fluororesin layer thickening step a desired number of times, and can provide desired release performance and wear resistance.
This surface treatment method can be applied not only as a method for producing the urethane mold 1, but also after the fluororesin layer 6 is peeled off or plated for a mold that has been molded many times and the surface layer is consumed. It can also be applied to regenerate the surface film after the layer 4 is peeled off and the plated layer 4 is laminated again.

Example 1
Of the vehicle seat pad molding die produced by aluminum casting, the molding surface of the lower mold was polished, and then a nickel plating layer having a thickness of 40 μm was laminated on the molding surface by a known method. Next, the surface of the plating layer is immersed in a fluororesin dispersion (solid content: 20 to 30%) containing PTFE as a fluororesin, and then dried in a drying furnace at 280 ° C. for 120 minutes to obtain a fluororesin having a thickness of 5 μm. A layer was formed. The resulting mold was taken as Example 1.
(Example 2)
In the same manner as in Example 1, a nickel plating layer was laminated, and the surface of the plating layer was immersed in a fluororesin dispersion (solid content: 40 to 60%) containing PTFE as a fluororesin, and then the same as in Example 1 It dried on conditions, and the 65-micrometer-thick fluororesin layer was formed. The obtained mold was referred to as Example 2.

(Comparative Examples 1-4)
Comparative example 1 and example 1 that were not polished on the molding surface of the lower mold of the vehicle seat pad similar to the example 1 produced by aluminum casting were compared. Comparative Example 3 was obtained by applying a nickel plating layer having a thickness of 40 μm in the same manner as in Example 2 and Example 1. Further, as Comparative Example 4, the same as in Example 1, except that the molding surface of the lower mold of the vehicle seat pad produced by aluminum casting as in Example 1 is polished and the thickness is 10 μm. A plating layer was laminated. Next, the surface of the plating layer was immersed in a fluororesin dispersion (solid content: 10 to 20%) containing PTFE as a fluororesin, and then dried under the same conditions as in Example 1 to obtain a fluororesin having a thickness of 3 μm. A layer was formed. The obtained mold was set as Comparative Example 4.
Table 1 shows the surface treatment conditions of Examples 1 and 2, and Table 1 shows the surface treatment conditions of Comparative Examples 1 to 4, respectively.

(Evaluation of releasability)
About the shaping | molding die of Example 1, 2 and Comparative Examples 1-4, it heat-retains at 65 +/- 4 degreeC, A polyol component (TLB-213, Asahi Glass Urethane Co., Ltd. product) and tolylene diisocyanate type | system | group with a soft foaming urethane high pressure injection machine. And a mixture of methylene diisocyanate-based isocyanate (Coronate C-1021, manufactured by Nippon Polyurethane Industry Co., Ltd.) was poured into the lower mold. Thereafter, the upper mold was immediately closed, and urethane was foamed and cured at 65 ± 4 ° C. for 6 minutes. Then, after opening the upper mold, the end of the urethane foam molded product was held by hand and released from the lower mold. At this time, the degree of peeling was visually confirmed and evaluated. The results are shown in Tables 1 and 2. The evaluation criteria are as follows.
○: As in the case of using a known release agent, it was peeled off without tearing Δ: The surface of the portion formed into the deep convex portion was torn from the molded body and remained on the mold surface ×: over the entire surface of the molded product Breaking was observed, and the surface remained on the mold surface (material breakage state)

  From the results of Tables 1 and 2, in Examples 1 and 2 including a plating layer and a fluororesin layer laminated in a state impregnated in the plating layer, the release property equivalent to that when a release agent is used is obtained. It was obtained and it became clear that a urethane foam molded product can be shape | molded without using a mold release agent. Moreover, even if it provided with the plating layer and the fluororesin layer, in the comparative example 4 with a small whole thickness, sufficient mold release property was not obtained. From this, it became clear that a good release property can be obtained when the plating layer has a thickness exceeding 10 μm and the fluororesin layer has a thickness of 5 μm or more.

(Evaluation of scratch resistance)
For the molds of Example 1 and Example 2, the presence or absence of scratches was visually observed using a tool defined in JIS G4401 as a tool based on JIS H8504 “Keishi Test Method” and evaluated for scratch resistance. .
Further, as Comparative Example 5, scratch resistance was evaluated for PTFE blocks (lumps) by the same experiment. The results are shown in Table 3. In addition, the case where a scratch was observed visually was set to x, and the case where it was not observed was set to (circle).

  From Table 3, in Examples 1 and 2 including a plating layer and a fluororesin layer laminated in a state impregnated in the plating layer, better scratch resistance was shown compared to Comparative Example 5.

It is sectional drawing of the molding surface of one Embodiment of the shaping | molding die for urethanes of this invention.

Explanation of symbols

1 Mold for urethane 2 Mold 4 Plating layer 6 Fluororesin layer

Claims (5)

A plating layer containing at least one of nickel, chromium and zinc on the molding surface of the mold;
A molding die for urethane, comprising: a fluororesin layer provided on the plating layer in a state where the plating layer is impregnated.   2. The urethane molding die according to claim 1, wherein the plating layer is thicker than 10 μm, and the surface treatment layer including the plating layer and the fluororesin layer is 15 μm or more.   The urethane mold according to claim 1 or 2, wherein the thickness from the surface of the plating layer to the surface of the fluororesin layer is 5 µm or more. A surface treatment method for a urethane mold,
An immersion step of immersing a molding surface provided with a plating layer containing at least one of nickel, chromium and zinc in a fluororesin dispersion in which fluororesin particles are held in a dispersed state;
A surface treatment method for a molding die for urethane, comprising a baking step of drying the molding surface after the immersion step at a high temperature. Thickening the fluororesin layer by immersing the molding surface provided with the fluororesin layer impregnated in the plating layer through the baking step in a fluororesin dispersion in which fluororesin particles are held in a dispersed state, and drying the molding surface after immersion at a high temperature The molding die surface treatment method for urethane according to claim 4 which has a process 1 or more times.

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