JP5561101B2 - Method for producing polyurethane foam molded article - Google Patents

Description

  The present invention relates to a method for producing a polyurethane foam molded article, and in particular, two or more polyurethane foam molded parts having different physical properties or characteristics by injecting two or more kinds of urethane stock solution into a foam molding mold and foaming. The present invention relates to a method for producing a polyurethane foam molded product, in which a polyurethane foam molded product having the above is integrally molded.

  A vehicle seat pad attached to a seat of an automobile or the like is generally made of a flexible polyurethane foam or a semi-rigid polyurethane foam.

  In a vehicle seat pad, the weight of the occupant is the most under the seat bottom, and the material of this portion is closely related to the seating comfort and riding comfort. Therefore, the constituent material of the lower part of the hip is important from the viewpoint of sitting comfort and riding comfort, but the other parts have a small weight load and are relatively low in importance.

  As a vehicle seat pad that achieves weight reduction and cost reduction without impairing sitting comfort, riding comfort, and durability, a part or all of the seat surface other than the bottom part of the seat is lower than the material constituting the bottom part. Japanese Patent Application Laid-Open No. 2002-353102 discloses a vehicle seat pad made of a material having a density and a hardness substantially equal to each other. As mentioned above, from the viewpoint of sitting comfort, riding comfort, and durability, there is no heavy load on the parts other than the bottom of the bottom, and therefore the hardness of the material constituting the bottom of the bottom is almost the same. For example, a sufficiently good performance can be obtained even if an inexpensive material having a low density is used for a portion other than the bottom portion.

  As a method for forming a polyurethane foam, a method in which two or more kinds of urethane stock solutions are injected into a mold simultaneously or at a time difference and integrally molded is conventionally performed. In Table 2004/058473, the polyurethane foam is prepared by setting the injection amount of the urethane stock solution so that a predetermined molding pressure (maximum internal pressure reached in the foam molding die during foam molding) is set in any molding part. One-piece molding is described. In this way, by setting the injection amount of the urethane stock solution so that a predetermined molding pressure is obtained at any molding part, each molded part has a desired physical property or characteristic more reliably. Can be manufactured.

  In addition, when injecting the first urethane undiluted solution to one half side of the mold and injecting another type of second urethane undiluted solution to the other half side, when simultaneously injecting the first urethane undiluted solution and the second urethane undiluted solution, The first urethane stock solution and the second urethane stock solution are mixed near the center of the mold. On the other hand, when the second urethane stock solution is injected after a predetermined time delay from the injection of the first urethane stock solution, the second foam is cured after the first foam that is foaming from the first urethane stock solution is cured to some extent. Since the second foam from the stock solution contacts the first foam, the first foam and the second foam are not so mixed. As a result, a molded body composed of the first molded part foam-molded from the first urethane stock solution and the second molded part foam-molded from the second urethane stock solution has a relatively clear boundary between them. Molded to have a part.

  According to such a time difference injection method, for example, a polyurethane foam seat pad in which a low-density thigh lower part and a high-density bottom part are clearly separated is manufactured. Of course, this seat pad is integrated in a series from the lower thigh to the lower buttocks, but has a density distribution in which the density clearly changes from the lower thigh to the lower buttocks near the boundary between the lower thigh and the lower buttocks.

JP 2002-353102 A Table 2004/058473

  In manufacturing polyurethane foam molded products by integrally molding two or more molded parts with different physical properties or characteristics, the urethane stock solution for molding each molded part is injected into the foam molding mold with a time lag. In the case of foaming, the previously injected urethane stock solution (hereinafter referred to as the first urethane stock solution) starts foaming earlier than the later injected urethane stock solution (hereinafter referred to as the second urethane stock solution). Therefore, a molded part foam-molded from the first urethane stock solution (hereinafter referred to as the first molded part) and a molded part foam-molded from the second urethane stock solution (hereinafter referred to as the second molded part). The first urethane undiluted solution first reaches the planned boundary position (the boundary between the first molded part and the second molded part on the design), and the second molding is performed beyond the planned boundary position. It expands to the part side.

  In this case, the second urethane stock solution that has started to foam later expands so as to push back the first urethane stock solution. However, the first urethane stock solution that has started foaming earlier is prior to the second urethane stock solution. Since the resin is made (cured) and the viscosity is increased, the second urethane stock solution may not be able to push the first urethane stock solution back to the planned boundary position.

  In particular, the larger the time difference Δt from the injection of the first urethane stock solution to the injection of the second urethane stock solution, the greater the first molding part exceeds the planned boundary position, and the first molding part And the second molding part are separated from the planned boundary position.

  According to the present invention, in a method for producing a polyurethane foam molded article in which two or more polyurethane foam molded parts having different physical properties or characteristics are integrally formed, the boundary between the molded parts can be arranged at a design position with higher accuracy. It is an object of the present invention to provide a method for producing a possible polyurethane foam molded article.

According to the method for producing a polyurethane foam molded article of the present invention (claim 1), two or more kinds of urethane stock solutions capable of molding polyurethane foams having different physical properties or characteristics are injected into a foaming mold and foamed. A method for producing a polyurethane foam molded product, in which a polyurethane foam molded product having two or more polyurethane foam molded parts having different physical properties or characteristics is integrally molded, wherein each urethane stock solution is placed in a foam molding mold with a predetermined time difference. In the method of manufacturing a polyurethane foam molded article that is injected into a foam and assuming that each urethane stock solution is injected into the foam molding mold at the same time, the same predetermined molding is performed in any polyurethane foam molded part at the time of molding. Determine the amount of each urethane stock solution to be used as a pressure, and use this amount for each urethane stock solution. A quasi injection volume, the greater the difference the predetermined time,
a) The injection amount of the urethane stock solution to be injected later is made larger than the reference injection amount.
b) The injection amount of the urethane stock solution injected first is less than the reference injection amount.
In addition to correcting the injection amount consisting of at least one of the above, each urethane stock solution was molded into the foam molding mold with a predetermined time difference and foamed, and was molded with the urethane stock solution previously injected. Each urethane raw material that makes it possible to push back the boundary between the molded part and the molded part molded with the urethane stock solution injected later to the designed boundary position by the expansion force of the urethane stock solution injected later. The molding pressure of
The injection amount correction is performed based on the difference between the determined molding pressure and the predetermined molding pressure .

  The method for producing a polyurethane foam molded article according to claim 2 is the method according to claim 1, wherein two or more types of urethane stock solutions capable of molding polyurethane foams having the same hardness and different densities at the predetermined molding pressure are used as the foam molding metal. A polyurethane foam molded article having two or more polyurethane foam molded parts having the same hardness and different densities is integrally molded by being injected into a mold and foamed.

  A method for producing a polyurethane foam molded article according to claim 3 is based on the density of polyurethane foam molded by each urethane stock solution at the predetermined molding pressure and the design volume of each polyurethane foam molded part in claim 2. Then, the reference injection amount of each urethane stock solution is set.

  In the method for producing a polyurethane foam molded article according to the present invention (Claim 1), when it is assumed that each urethane stock solution is simultaneously injected into a foam molding die, it is predetermined in any polyurethane foam molded part during molding. The injection amount of each urethane undiluted solution is determined so that the molding pressure becomes the same, and this injection amount is set as the reference injection amount of each urethane undiluted solution. And at the time of manufacturing polyurethane foam molded products, based on the time difference of injection of each urethane stock solution, the injection amount of the urethane stock solution to be injected later is made larger than the reference injection amount or the injection of the urethane stock solution to be injected first. The amount is made smaller than the reference injection amount, or both are performed to correct the urethane stock solution injection amount.

  In this way, by correcting the injection amount of the urethane stock solution, it is possible to arrange the boundary portion between the molded portions at the design position with higher accuracy.

  The present invention is suitable for producing a polyurethane foam molded article having two or more polyurethane foam molded parts having the same hardness and different densities as described in claim 2. In this case, at a predetermined molding pressure, two or more types of urethane stock solutions capable of forming polyurethane foams having the same hardness and different densities are injected into a foaming mold to cause foaming more reliably. It is possible to integrally form a polyurethane foam molded product in which the foam molded portion has a desired hardness and density.

  In this case, as in claim 3, based on the density of the polyurethane foam molded with each urethane stock solution at the predetermined molding pressure and the design volume of the polyurethane foam molded part molded with each urethane stock solution, It is preferable to set the reference injection amount of the urethane stock solution. By doing in this way, it becomes possible to easily set the reference injection amount of each urethane stock solution.

  As in claim 4, when each urethane stock solution is injected into the foaming mold with the predetermined time difference and foamed, a molded part molded with the urethane stock solution injected earlier, and later Obtaining the molding pressure of each urethane raw material that allows the boundary part with the molded part molded by the injected urethane stock solution to be pushed back to the designed boundary position by the expansion force of the urethane stock solution injected thereafter, By correcting the injection amount of the urethane stock solution based on the difference between the determined molding pressure and the predetermined molding pressure, the optimal injection amount of each urethane stock solution can be easily set according to the time difference of each urethane stock solution injection. In addition, it can be obtained with high accuracy.

  In the present invention, the density of the polyurethane foam means “OA density (overall density; total density)”. OA density is measured by dividing the weight of the polyurethane foam by the volume (foam weight / volume). The hardness is “25% hardness”. This 25% hardness is obtained by compressing polyurethane foam with a pressure plate having a diameter of 200 mm until the thickness reaches 25% before pressing, and measuring the load at that time.

It is explanatory drawing of the manufacturing method of the polyurethane foam molded article which concerns on embodiment. It is explanatory drawing at the time of inject | pouring a 1st urethane undiluted | stock solution and a 2nd urethane undiluted | stock into a foaming metal mold | die, without correct | amending injection amount, and manufacturing a polyurethane foam molded article. It is explanatory drawing of how to obtain | require the reference | standard injection amount of the 1st urethane stock solution and the 2nd urethane stock solution in the manufacturing method of the polyurethane foam molded article of FIG. It is a graph which shows the relationship between the injection time difference in a reference example, and the density of each shaping | molding part. It is a graph which shows the relationship between the injection time difference in a reference example, and correction | amendment molding pressure.

  Hereinafter, embodiments will be described with reference to the drawings. In each of the following embodiments, a method for producing a polyurethane foam molded article in which two parts of a polyurethane foam molded part having different physical properties or characteristics are integrally formed is illustrated, but the present invention has physical properties or characteristics. The present invention can also be applied to a method for producing a polyurethane foam molded product in which three or more different polyurethane foam molded parts are integrally molded.

  FIG. 1 is a schematic cross-sectional view of a foam molding die for explaining a method for producing a polyurethane foam molded article according to an embodiment, and FIG. 2 shows a first urethane stock solution and a second urethane stock solution. FIG. 2 is a schematic cross-sectional view of a foam molding die for explaining a case where a polyurethane foam molded article is manufactured by injecting the above into a foam molding die without correcting each injection amount. 1 and 2, respectively, (a) shows the time when the first urethane undiluted solution is injected into the first molding space of the foam molding die, and (b) shows the foam molding die. The second urethane stock solution is injected into the second molding space, (c) the figure shows the middle of foaming of the first urethane stock solution and the second urethane stock solution, and (d) the figure shows the second The time of completion of foaming of the first urethane stock solution and the second urethane stock solution is shown. FIG. 3 is an explanatory view of how to obtain the reference injection amount of the first urethane undiluted solution and the second urethane undiluted solution in the manufacturing method of this polyurethane foam molded article, and FIG. 3 (a) shows the molding pressure of the urethane undiluted solution, It is a graph which shows the relationship with the OA density of the shape | molded polyurethane foam, (b) figure is a graph which shows the relationship between 25% hardness of this polyurethane foam, and OA density.

  Hereinafter, a method for producing a polyurethane foam molded article 1 formed by integrally molding two parts of polyurethane foam molded parts (hereinafter sometimes simply referred to as molded parts) 2 and 3 having different physical properties and characteristics will be described. In FIG. 1 (explanation), the polyurethane foam molded article 1 is illustrated as a rectangular parallelepiped shape, but the shape of the polyurethane foam molded article 1 is not limited to this. In this embodiment, the polyurethane foam molded article 1 has a first molding portion 2 on one half side in the longitudinal direction (left and right direction in FIG. 1 (d)) and a second molding portion 3 on the other half side. It has become. In addition, the shape and arrangement | positioning of each shaping | molding part 2 and 3 are not limited to this.

The first molding part 2 and the second molding part 3 are made of polyurethane foam having a hardness H ₁ and a density D ₁ at a predetermined molding pressure P (maximum internal pressure reached in the foam molding die during foam molding) P. A first polyurethane undiluted solution U ₁ that can be molded and a _second polyurethane foam that can be molded with a hardness H ₂ and a density D ₂ with this predetermined forming pressure (that is, the same forming pressure as the _first urethane undiluted solution U ₁ ). urethane stock solution U ₂ and the foam mold is integrally molded by respectively be foamed by a predetermined amount injected (hereinafter, simply. may be abbreviated as mold) 10. The polyurethane foam first urethane stock solution U ₁ is foamed molded first molded portion 2, a second molding part 3 is formed by polyurethane foams second urethane stock solution U ₂ is formed by foaming .

In this embodiment, the hardnesses H ₁ and H ₂ are substantially the same, and the densities D ₁ and D ₂ are different. When the polyurethane foam molded article 1 is a vehicle seat pad, the hardness being substantially the same means that the hardness difference is 20 N or less, particularly 0 to 4.9 N. The different densities, the density difference is 3 kg / ^{m 3} or more, in particular 10 to 50 kg / ^{m 3} refers to the extent different. As described above, the density is OA density and the hardness is 25% hardness.

  The mold 10 has a lower mold 11 and an upper mold 12. The inside of the mold 10 sandwiches a planned boundary position BL between the first molding part 2 and the second molding part 3 (a boundary part between the first molding part 2 and the second molding part 3 in design). One half side is a first molding space 13 for molding the first molding part 2, and the other half side is a second molding space 14 for molding the second molding part 3. . In this embodiment, the molding spaces 13 and 14 are horizontally continuous. In this embodiment, the planned boundary position BL is arranged in the middle in the longitudinal direction of the polyurethane foam molded article 1 so that the first molded portion 2 and the second molded portion 3 have substantially the same shape and volume. However, the arrangement of the planned boundary position BL is not limited to this.

The upper mold 12 is injected with a first injection section 15 for injecting the _first urethane stock solution U ₁ into the first molding space 13 and the second urethane stock solution U ₂ into the second molding space 14. A second injection part 16 is provided. The first injection part 15 is arranged above the central part of the first molding space 13, and the second injection part 16 is arranged above the central part of the second molding space 14, so that the first injection The distance from the part 15 to the planned boundary position BL is equal to the distance from the second injection part 16 to the planned boundary position BL.

In producing the polyurethane foam molded article 1, first, as shown in FIG. 1 (a) or 2 (a), the first injection portion 15 enters the first molding space 13 at the time t ₁ as shown in FIG. injecting urethane stock solution _{U 1.} Urethane stock U ₁ starts foaming immediately after the injection. If this time t ₁ from the predetermined time Δt becomes time t ₂ has elapsed, the from the street of FIG. 1 (b) or FIG. 2 (b) the second injection unit 16 into the second molding space 14 2 of the urethane stock solution _{U 2} is injected. Urethane stock solution U ₂ starts foaming immediately after the injection.

Since the first of the urethane stock solution U ₁ starts the fast foaming only Δt than the second urethane stock solution U _2, the first of urethane stock solution U ₁ is inflated until the planned boundary position BL earlier. At this time, since the second urethane stock solution U ₂ is not inflated by the scheduled boundary position BL, urethane stock solution U ₁ wherein the first, then, as FIG. 1 (c) or FIG. 2 (c), It expands beyond the planned boundary position BL to the second molding space 14 side. Thereafter, the second urethane stock solution U ₂ that has started to foam later expands so as to push back the first urethane stock solution U ₁ to the planned boundary position BL, but the first urethane stock solution U ₁ that has started foaming _first is Since the resin is made (cured) prior to the second urethane stock solution U ₂ and the viscosity is increased, the second urethane stock solution U ₂ sufficiently passes the first urethane stock solution U ₁ to the planned boundary position BL. It may not be possible to push back. In this case, as shown in FIG. 2 (d), the boundary portion between the molded portions 2 ′ and 3 ′ of the molded polyurethane foam molded product 1 ′ is located closer to the second molding space 14 than the planned boundary position BL. It will be a thing.

The first and the injection time t ₁ urethane stock solution U ₁ as the second time difference Δt between the injection time t ₂ of urethane stock solution U ₂ is large (long), the first mold part 2 and the second molding space 14 The boundary between the molded parts 2 and 3 in the molded product 1 is located closer to the second molding space 14 than the planned boundary position BL.

The injection amount of the first urethane undiluted solution U ₁ is decreased, the injection amount of the second urethane undiluted solution U ₂ is increased, or the injection amount of the first urethane undiluted solution U ₁ is decreased and the second urethane undiluted solution is added. by increasing the injection amount of U _2, for the second molding pressure of urethane stock solution U ₂ is increased, that the second mold part 3 pushes back strongly first mold part 2 at the scheduled boundary position BL side Therefore, the boundary between the molding parts 2 and 3 matches or approaches the planned boundary position BL.

Therefore, in the present invention, the larger the time difference Δt (= t ₁ −t ₂ ), the smaller the injection amount of the first urethane stock solution U ₁ compared to the reference injection amount of the urethane stock solutions U ₁ and U ₂ . The injection amount of the second urethane stock solution U ₂ is increased, or the injection amount of the first urethane stock solution U ₁ is decreased and the injection amount of the second urethane stock solution U ₂ is increased. In particular, if the relationship between the injection time difference Δt and the molding pressure of each of the urethane stock solutions U ₁ , U ₂ is determined at that time, the molding part 2, ₂ is expanded by the expansion force of the _second urethane stock solution U _{2 at} the injection time difference Δt. to push back 3 of the boundary portion to the expected boundary position BL whether the molding pressure of the urethane stock solution U ₂ of the second it is sufficient to what extent elevated from the predetermined molding pressure P (hereinafter, the second urethane stock solution U a correction amount from the predetermined molding pressure P ₂ of the molding pressure that correction molding pressure [Delta] P _2.), or the first molding pressure urethane stock solution U ₁ it is sufficient to degree reduced from the predetermined molding pressure P (Hereinafter, the correction amount of the molding pressure of the first urethane stock solution U ₁ from the predetermined molding pressure P is referred to as a correction molding pressure ΔP ₁ ), and the injection amount of the urethane stock solutions U ₁ and U ₂ is thereby determined. How accurate it is to correct It can be determined. A method for obtaining the corrected molding pressures ΔP ₁ and ΔP ₂ will be described later.

Since the reference injection amount of this urethane stock solution varies depending on the blending of the urethane stock solution, the method for determining the blending of the urethane stock solution will be described first. In this embodiment, each urethane stock solution U ₁ , U ₂ is prepared as follows.

  The density of the polyurethane foam to be molded is determined mainly by the amount of water as a foaming agent contained in the polyol compounded liquid of the urethane stock solution.

Therefore, in preparing the urethane stock solution, the amount of water in the polyol blend solution is adjusted, and as shown in Example 1 described later, the relationship between the molding pressure and the OA density of the polyurethane foam molded from the two types of urethane stock solution ( FIG. 3 (a)) is examined. And, at the same molding pressure, two types of urethane stock solutions having different OA densities and a desired OA density difference, that is, a urethane stock solution for molding a higher density polyurethane foam (hereinafter referred to as “high density urethane stock solution”). And a composition of a urethane stock solution for molding a lower density polyurethane foam (hereinafter referred to as “low density urethane stock solution”). At this time, in the same molding pressure, the density of the high density polyurethane foam to be molded by a high-density urethane stock solution and D _H, the density of the low density polyurethane foam which is formed by the low-density urethane stock solution and D _L ( D _H > D _L ).

Next, for this high density polyurethane foam and low density polyurethane foam, as shown in Example 1 described later, the relationship between OA density and 25% hardness (FIG. 3 (b)) was examined. when the density of the foam is D _H, the density of the low density polyurethane foam as 25% hardness equivalent to the hardness when the D _L is obtained, adjusting the isocyanate index of the high density urethane stock solution. For this adjustment, for example, it is only necessary to finely adjust the blending of the isocyanate component and the polyol blending liquid. By making such adjustments, the relationship between the density and the molding pressure of the polyurethane foam molded with the high-density urethane stock solution hardly changes. Therefore, at the same molding pressure, the same hardness and different density. The composition of the high-density urethane stock solution and the low-density urethane stock solution that can form a polyurethane foam can be set. Thus using high density urethane stock solution and low density urethane stock solution was prepared as the first urethane stock solution U ₁ and second urethane stock solution U _2. In this embodiment, the high-density urethane stock solution first urethane stock solution U _1, the low-density urethane stock solution and the second urethane stock solution U _2. Incidentally, on the contrary, the low-density urethane stock solution first urethane stock solution U _1, may high density urethane stock solution as a second urethane stock solution U _2.

Adjustment of the isocyanate index, when the density of the low density polyurethane foam of D _L, as the density of the high density polyurethane foam is obtained 25% hardness equivalent to the hardness when the D _H, low density urethane It may be performed on the stock solution.

  The method for preparing the above urethane stock solution is the same as in the above-mentioned Table 2004/058473.

  The above preparation method is an example of a method for preparing two types of urethane stock solutions capable of forming polyurethane foams having the same hardness and different densities at the same molding pressure, and the method for preparing a urethane stock solution in the present invention is as follows. The method is not limited to the above method.

Thus the first reference injection amount of the urethane stock solution U ₁ and second urethane stock solution U ₂ which is prepared is determined in the following manner.

First, the density D _H, the D _L, in assuming that the first urethane stock solution U ₁ and second urethane stock solution U ₂ simultaneously injection, a predetermined same molding pressure P in the molding spaces 13 and 14 The injection amounts of the obtained _first urethane undiluted solution U ₁ and second urethane undiluted solution U ₂ are determined, and the injection amounts at this time are used as the first urethane undiluted solution U ₁ in actually producing the polyurethane foam molded article _1. And the reference injection amounts G ₁ and G _{2 of} the second urethane stock solution U ₂ . Specifically, the reference injection amount G ₁ of the first urethane undiluted solution U ₁ is obtained from the product of the volume V _{1 of} the first molding space 13 and the density _DH (G ₁ = V ₁ × D _H ). The reference injection amount _{G 2} of the second urethane stock solution _{U 2} is determined from the product of the volume _{V 2} of the second molding space 14 the density _{D L (G 2 = V 2} × D L).

Next, regarding the first urethane stock solution U ₁ and the second urethane stock solution U _{2, the} relationship between the injection time difference Δt and the corrected molding pressures ΔP ₁ and ΔP ₂ as shown in FIG. Based on the corrected molding pressures ΔP ₁ and ΔP ₂ at the injection time difference Δt, the reference injection amounts G ₁ and G ₂ are corrected, and the first urethane undiluted solution U ₁ when the polyurethane foam molded article 1 is actually manufactured (mass produced) and setting a second injection amount of the urethane stock solution U _2.

That is, as the time difference Δt increases, the injection amount of the first urethane stock solution U ₁ is decreased or the injection amount of the second urethane stock solution U ₂ is increased as compared with the reference injection amounts G ₁ and G ₂ . or to reduce the first injection amount of the urethane stock solution U ₁ and to increase the second injection amount of the urethane stock solution U _2.

The relationship between the injection time difference Δt and the corrected molding pressures ΔP ₁ and ΔP ₂ is obtained based on the trial production as follows. At this time, it is preferable to perform a trial production using a test piece molding die instead of a trial production using a die that is actually used for manufacturing (mass production) the polyurethane foam molded article 1. In general, this test piece molding die is formed by foaming a urethane stock solution into a rectangular parallelepiped shape of a predetermined size, and its foaming characteristics (molding pressure, etc.) and the physical properties (density, etc.) of the polyurethane foam after molding. It is used to investigate. In this embodiment, each of the test piece molding dies has a rectangular parallelepiped shape (the lengths of the sides in the two orthogonal directions of the bottom are 400 mm and 200 mm, and the height is 100 mm, respectively) and the second molding space 13. The molding space 14 is connected horizontally, and an injection part for injecting the urethane stock solution is provided at the center of the ceiling part of each molding space. In the test piece molding die, pressure sensors for measuring molding pressures in the first molding space 13 and the second molding space 14 are provided. By the first of the first urethane stock solution U ₁ was injected into the molding space, thereby foaming by injecting the second urethane stock solution U ₂ in the second molding space with a predetermined time difference Delta] t, the first the first portion 2 which is formed by urethane stock solution U ₁ test piece having a 'and a second portion 3 which is formed by the second urethane stock solution U _2' (prototype) 1 'is obtained. FIG. 2 shows the test piece manufacturing process.

The relationship between the injection time difference Δt and the corrected molding pressure ΔP _{1 of} the first urethane stock solution U ₁ can be obtained as follows. When a certain injection time difference Delta] t, the preform 1 with a reduced first injection amount of the urethane stock solution U ₁ from the reference injection amount G ₁ gradually 'a plurality prototype, the prototype 1' in the first mold The density D ₁ ′ of the part 2 ′ is measured respectively. As a result, the difference between the density D 1 ′ of the first molded part 2 ′ in each prototype ₁ ′ and the set density D ₁ of the first molded part 2 in the mass-produced product can be understood. From the density difference (D ₁ ′ −D ₁ ), a correction molding pressure ΔP ₁ necessary to eliminate this density difference is calculated. The corrected molding pressure ΔP ₁ is substantially proportional to the density difference (for example, when D ₁ ′ −D ₁ = ΔD ₁ kg / m ³ , the corrected molding pressure ΔP ₁ from the predetermined molding pressure P is set. Is approximately pΔD ₁ (p is a proportional constant, specifically, p = 0.047) kgf / cm ² ). For example, if a prototype 1 ′ is obtained in which the boundary between the molded parts 2 ′ and 3 ′ substantially matches the planned position while a plurality of prototypes 1 ′ are prototyped. Calculates the corrected molding pressure ΔP ₁ from the difference between the density D 1 ′ of the prototype ₁ ′ and the set density D ₁ of the mass-produced product. Alternatively, even if the boundary between the molded parts 2 ′ and 3 ′ of each prototype 1 ′ does not match the planned position in the design, the interpolation is performed from the value of the density D ₁ ′ of the plurality of molded products 1 ′. Thus, the density D ₁ ′ when the boundary between the molded parts 2 ′ and 3 ′ substantially matches the planned position on the design is predicted, and the interpolation value of this density D ₁ ′ and the set density D _{1 of the} mass-produced product are predicted. The correction molding pressure ΔP ₁ can also be calculated from the difference between the two. By repeating this several times while changing the injection time difference Δt, a graph showing the relationship between the injection time difference Δt and the corrected molding pressure ΔP _{1 of} the first urethane stock solution U ₁ as shown in FIG. 5 is obtained.

The relationship between the injection time difference Δt and the corrected molding pressure ΔP _{2 of} the second urethane stock solution U ₂ is obtained as follows. At a certain injection time difference Δt, a plurality of prototypes 1 ′, in which the injection amount of the second urethane undiluted solution U ₂ is gradually increased from the reference injection amount G ₂ , are prototyped, and the second molding is performed on each prototype 1 ′. The density D ₂ ′ of the part 3 ′ is measured. Thus, the density D _{2 'of} the' second mold part 3 in the 'each preform 1, since whether the difference between a degree of the set density D ₂ of the second molding part 3 of the mass production is seen, From the density difference (D ₂ ′ −D ₂ ), a correction molding pressure ΔP ₂ necessary to eliminate the density difference is calculated. The corrected molding pressure ΔP ₂ is substantially proportional to the density difference (for example, when D ₂ ′ −D ₂ = ΔD ₂ kg / m ³ , the corrected molding pressure ΔP ₂ from the predetermined molding pressure P is set. Is approximately pΔD ₂ (p is a proportional constant, specifically, p = 0.052) kgf / cm ² ). For example, if a prototype 1 ′ is obtained in which the boundary between the molded parts 2 ′ and 3 ′ substantially matches the planned position while a plurality of prototypes 1 ′ are prototyped. calculates a correction molding pressure [Delta] P ₂ from the difference between the set density D ₂ of the mass-produced 'density D _2' in this prototype 1. Alternatively, even if the boundary between the molded parts 2 ′ and 3 ′ of each prototype 1 ′ does not match the planned position on the design, the interpolation is performed from the value of the density D ₂ ′ of the plurality of molded products 1 ′. Thus, the density D ₂ ′ when the boundary between the molded parts 2 ′ and 3 ′ substantially matches the planned position on the design is predicted, and the interpolation value of this density D ₂ ′ and the set density D _{2 of the} mass-produced product are predicted. The correction molding pressure ΔP ₂ can also be calculated from the difference between the _two . By repeating this several times while changing the injection time difference Δt, a graph showing the relationship between the injection time difference Δt and the corrected molding pressure ΔP _{2 of} the second urethane stock solution U ₂ as shown in FIG. 5 is obtained.

The corrected molding pressure [Delta] P _1, on the basis of the [Delta] P _2, or the second injection amount of the urethane stock solution U ₂ it is sufficient to what extent increases from the reference injection amount G ₂ (hereinafter, the second urethane stock solution U ₂ correction amount from the reference injection amount G ₂ injection amount of correction injection amount ΔG _2.), or a first injection amount of the urethane stock solution U ₁ it is sufficient to degree reduced from the reference injection amount G ₁ (hereinafter, the correction amount from the reference injection amount G ₁ of the first injection amount of the urethane stock solution U ₁ that correction injection amount .DELTA.G _1.) is obtained. Specifically, when the correction injection amount ΔG ₂ is obtained, the correction molding pressure ΔP ₂ at the injection time difference Δt is obtained from the graph of the injection time difference Δt and the correction molding pressure ΔP ₂ . Then, in order to increase the molding pressure of the second urethane raw solution U _{2 by} the corrected molding pressure ΔP ₂ , how much the injection amount of the second urethane raw solution U ₂ should be increased from the reference injection amount G _2. Or calculate. The calculated value is the correction injection amount .DELTA.G _2. Further, when the correction injection amount ΔG ₁ is obtained, the correction molding pressure ΔP ₁ at the injection time difference Δt is obtained from the graph of the injection time difference Δt and the correction molding pressure ΔP ₁ . Then, in order to lower the molding pressure of the first urethane stock solution U ₁ by this corrected molding pressure ΔP ₁ , how much the injection amount of the first urethane stock solution U ₁ should be reduced from the reference injection amount G _1. Or calculate. The calculated value is the correction injection amount .DELTA.G _1.

As described above, when the corrected molding pressures ΔP ₁ and ΔP ₂ for the injection time difference Δt are calculated, the urethane is accurately determined regardless of the change in the formulation of the urethane stock solutions U ₁ and U ₂ or the change in the combination of the formulations. Correction injection amounts ΔG ₁ and ΔG ₂ of the stock solutions U ₁ and U ₂ can be obtained.

In the present invention, the determination of the specific urethane stock solution U _1, U ₂ injection volume increase or decrease the amount, do one of the following injection amount correction method 1-3.

[Injection amount correction method 1]
Obtain correction molding pressure [Delta] P ₂ of the polyurethane foam molded article 1 from the actual injection time difference Δt during manufacture in the above procedure of the second urethane stock solution U _2, the correction injection amount .DELTA.G ₂ on the basis of the corrected molding pressure [Delta] P ₂ And the injection amount of the second urethane undiluted solution U ₂ is increased by the correction injection amount ΔG ₂ from the reference injection amount G ₂ .

By correcting in this way, the second urethane stock solution U ₂ tends to expand more greatly, so that the second urethane stock solution U ₂ can push back the _first urethane stock solution U ₁ more strongly. As shown in FIG. 4 (d), in the polyurethane foam molded article 1 after molding, the boundary between the molding parts 2 and 3 matches or approaches the planned boundary position BL (the boundary between the molding parts 2 and 3 and the schedule). The separation distance from the boundary position BL is preferably 50 mm or less, particularly preferably 20 mm or less. The boundary between the first molding part 2 and the second molding part 3 often enters a convex curved surface toward the second molding part 3 as shown in FIG. , 3 is the separation distance between the boundary between the three and the planned boundary position BL. The separation distance from the planned boundary position BL when the convex curved surface is viewed on average (the average separation between the convex curved surface and the planned boundary position BL). Distance).

[Injection amount correction method 2]
The calculated correction molding pressure [Delta] P ₁ of the polyurethane foam molded article 1 from the actual injection time difference Δt during manufacture by the above procedure first urethane stock solution U _1, the correction injection amount .DELTA.G ₁ on the basis of the corrected molding pressure [Delta] P ₁ And the injection amount of the first urethane undiluted solution U ₁ is made smaller than the reference injection amount G ₁ by this correction injection amount ΔG ₁ .

By correcting in this way, the force of the first urethane undiluted solution U ₁ to expand toward the second molding space 14 against the second urethane undiluted solution U ₂ becomes weak, and therefore the second urethane undiluted solution U ₂ can sufficiently push back the first urethane undiluted solution U _1, and in the polyurethane foam molded article 1 after molding, the boundary between the molded parts 2 and 3 matches or approaches the planned boundary position BL. It becomes like this.

[Injection amount correction method 3]
Determined correction molding pressure [Delta] P ₁ of the polyurethane foam molded article 1 from the actual injection time difference Δt during manufacture first urethane stock solution U _1, the second urethane stock solution U ₂ and a correction molding pressure [Delta] P _2, this correction molding Based on the pressures ΔP ₁ and ΔP ₂ , the injection amount of the first urethane raw solution U ₁ is made smaller than the reference injection amount G ₁ and the injection amount of the _second urethane raw solution U ₂ is changed to the reference injection amount G _2. More than that.

In this case, for example, correction molding pressure [Delta] P _1, the correction injection amount .DELTA.G ₁ of the urethane stock solution _U 1, _{U 2} obtained based on [Delta] P _2, adding or subtracting .DELTA.G ₂ to each of the reference injection amount _G 1, _{G 2} Instead, the injection amount of the second urethane stock solution U ₂ is increased by ΔG ₂ / m from the reference injection amount G ₂ , and the injection amount of the _first urethane stock solution U ₁ is set by ΔG ₁ / n. It is less than the reference injection amount G _1. Note that m and n are preferably m = n, and particularly preferably m = n = 2. By correcting in this way, the second urethane undiluted solution U ₂ tends to expand more, the first urethane undiluted solution U ₁ is pushed back more strongly, and the first urethane undiluted solution U ₁ becomes the second urethane undiluted. Since the force to expand toward the second molding space 14 against the stock solution U ₂ becomes weak, the second urethane stock solution U ₂ can sufficiently push back the _first urethane stock solution U _1. In the subsequent polyurethane foam molded article 1, the boundary between the molded portions 2 and 3 matches or approaches the planned boundary position BL.

The above correction method is an example, the correction method of the first urethane stock solution U ₁ and second injection amount of the urethane stock solution U ₂ in the present invention is not limited thereto. For example, the injection amount of the urethane stock solutions U ₁ and U ₂ may be corrected based on the trial production of the polyurethane foam molded article 1. The correction amounts of the urethane stock solutions U ₁ and U ₂ may be determined based on empirical rules. Further, according to the time difference Δt from when the first urethane undiluted solution U ₁ is poured into the mold 10 to when the second urethane undiluted solution U ₂ is poured into the mold 10, how much the first urethane undiluted solution U _{1 is.} and / or the second or the injection amount of the urethane stock solution U ₂ may be corrected in advance by clarifying the index in advance by experiment or the like, the first urethane stock solution U ₁ and / or the second urethane on the basis of the index the injection volume of the stock solution U ₂ may be corrected.

In this way, after correcting the injection amount of the first urethane stock solution U ₁ and / or the second urethane stock solution U _{2 from} the reference injection amounts G ₁ and G ₂ , respectively, the corrected injection amount is used at the time of mass production. A polyurethane foam molded article 1 is produced as an injection amount.

Hereinafter, the present invention will be described more specifically with reference to examples.

<Example 1>
A urethane stock solution A and a urethane stock solution B having the following composition were prepared. The urethane stock solution A has an isocyanate index of 36, and the urethane stock solution B has an isocyanate index of 41.

Regarding the urethane stock solution A and the urethane stock solution B, the relationship between the OA density and the molding pressure was examined, and the results are shown in FIG. 3 (a). From FIG. 3 (a), at the molding pressure P = 0.647 kgf / cm ² (63.4 kPa), the OA density of the polyurethane foam molded with the urethane stock solution A is 45.8 kg / m ³ , and the urethane stock solution B It can be seen that the OA density of the polyurethane foam molded by is 40 kg / m ³ and the density is different.

With respect to this urethane stock solution A and urethane stock solution B, the relationship between OA density and 25% hardness was examined, and the results are shown in FIG. 3 (b). As is apparent from FIG. 3 (b), when the OA density of the polyurethane foam molded from the urethane stock solution B is 40 kg / m ³ , the 25% hardness is 25.8 kgf, whereas the polyurethane foam is molded from the urethane stock solution A. When the polyurethane foam has an OA density of 45.8 kg / m ³ , the 25% hardness is 18 kgf, which is considerably lower than 25.8 kgf of the urethane stock solution B.

Then, about the urethane stock solution A, the mixing ratio of a polyol compound liquid and an isocyanate component was changed gradually, and the relationship between the OA density and 25% hardness in that case was investigated. As a result, as shown in FIG. 3 (b), the polyurethane foam molded from the urethane stock solution A ′ having an isocyanate index of 37.5 has 25% hardness when the OA density is 45.8 kg / m ^3. It was found to be the same 25.8 kgf. The relationship between the OA density and the maximum internal pressure of the polyurethane foam molded from the urethane stock solution A ′ is almost the same as the relationship between the OA density and the maximum internal pressure of the polyurethane foam molded from the urethane stock solution A. The maximum internal pressure at 45.8 kg / m ³ was 0.647 kgf / cm ² .

Based on the above circumstances, the polyurethane foam molded article 1 was molded using the following urethane stock solution A ′ and urethane stock solution B. The urethane stock solution A ′ is a first urethane stock solution U ₁ for molding the first molding part 2, and the urethane stock solution B is a second urethane stock solution U ₂ for molding the second molding part 3. did. In Example 1, P = 0.647 kgf / cm ² , D _H = 45.8 kg / m ³ , and D _L = 40 kg / m ³ . The volumes of the first molding space 13 and the second molding space 14 of the mold 10 were both 8000 cm ³ . The cavity volume of the mold 10 is 16000 cm ³ .

When this maximum pressure during molding in the cavity is to determine the reference injection amount _G 1, _{G 2} of the urethane stock solution so that the 0.647kgf / cm ² at any location in the cavity _U 1, _{U 2} G ₁ = 366.4 g and G ₂ = 320 g.

A prototype 1 ′ was manufactured using the reference injection amounts G ₁ and G ₂ as the injection amounts of the urethane stock solutions U ₁ and U ₂ , respectively. The time difference Δt from when the _first urethane stock solution U ₁ was injected into the mold 10 to when the second urethane stock solution U ₂ was injected into the mold 10 was 15 seconds. After the molding was completed, the densities D ₁ ′ and D ₂ ′ of the molded parts 2 ′ and 3 ′ of the prototype 1 ′ were measured. D ₁ 'is 0.3 kg / ^{m 3} smaller than _{D H, D 2'} became as large 0.3 kg / ^{m 3} than _{D L.} Therefore, from the graph showing the relationship between the correction molding pressure [Delta] P ₂ pre injection had been created time difference Delta] t and urethane stock solution U _2, was determined correction molding pressure [Delta] P ₂ urethane stock solution U ₂ in the case of Delta] t = 15 seconds However, since ΔP ₂ = 0.12 kgf / cm ² , the injection amount of the urethane stock solution U ₂ is set to ΔG ₂ = 18.5 g (that is, the molding pressure of the urethane stock solution U ₂ is set to 0 than the reference injection amount G _2). The amount of increase required to increase the amount by about 12 kgf / cm ² ) was corrected to 338.5 g, and the urethane stock solutions U ₁ and U ₂ were injected into the mold 10 with the corrected injection amount. Except for the above, a polyurethane foam molded article 1 was produced in the same manner as in the prototype 1 ′.

  When this polyurethane foam molded article 1 was cut in the longitudinal direction and the cross section was confirmed by visual observation, the boundary between the molded part 2 and the molded part 3 was located almost in the middle of the polyurethane foam molded article 1 in the longitudinal direction. It was.

  As described above in detail, according to the present invention, when producing a polyurethane foam molded product in which two or more polyurethane foam molded parts having different physical properties or characteristics are integrally molded, the boundary between the molded parts is more accurately detected. It is possible to arrange in the design position well.

<Reference example>
A urethane stock solution having the same composition (a urethane stock solution capable of forming a polyurethane foam of the same density at the same molding pressure P) is used as the first urethane stock solution U ₁ and the second urethane stock solution U ₂ , and this urethane stock solution is used in Example 1. A polyurethane foam molded article 1 was manufactured by injecting into the same mold 10 with a time difference Δt. At this time, the second urethane undiluted solution U ₂ is colored in blue so that the boundary (joint) between the first molded part 2 and the second molded part 3 after molding can be easily confirmed visually. I made it. The injection time difference Δt is changed to 6 seconds, 15 seconds, 20 seconds, and 25 seconds to produce polyurethane foam molded products 1 respectively. For each, the density of the molded parts 2 and 3 and the density of the molded parts 2 and 3 are The difference was measured. The results are shown in Table 4 and FIG. FIG. 4 is a graph of Table 4. From Table 4 and FIG. 4, it can be seen that the greater the injection time difference Δt, the greater the density difference (volume difference) between the molded parts 2 and 3 and the greater the degree.

The injection time difference Δt is fixed to 6 seconds, 15 seconds, 20 seconds, and 25 seconds, respectively, and a plurality of polyurethane foam molded products 1 are manufactured by trial production while gradually increasing the injection amount of the second urethane stock solution U _2. A search was made for a corrected molding pressure ΔP _{2 at} which the boundary between the molding parts 2 and 3 substantially matches the planned boundary position BL at the time difference Δt. The results are shown in FIG.

In this reference example, the correction molding pressure [Delta] P ₂ is determined as follows. When a certain injection time difference Delta] t, prototype 1 with increased second injection amount of the urethane stock solution U ₂ than portionwise reference injection amount G ₂ 'the plurality trial, the preform 1' in the molded part 2 ', The 3 ′ densities D ₁ ′ and D ₂ ′ are measured. Thereby, since the density D ₁ ′, D ₂ ′ of the molded parts 2 ′, 3 ′ in each prototype 1 ′ and the set density D ₁ , D ₂ in the mass-produced product can be seen, From the density difference (D ₂ ′ −D ₂ ), a correction molding pressure ΔP ₂ necessary to eliminate the density difference is calculated. As described above, the correction molding pressure ΔP ₂ is substantially proportional to the density difference. If a prototype 1 ′ is obtained in which the boundary between the molded parts 2 ′ and 3 ′ substantially matches the planned position while a plurality of prototypes 1 ′ are prototyped, from the difference between the set density D ₂ of the mass-produced 'density D _2' in prototype 1 calculates a correction molding pressure [Delta] P _2. Alternatively, even if the boundary between the molded parts 2 ′ and 3 ′ of each prototype 1 ′ does not match the planned position on the design, the interpolation is performed from the value of the density D ₂ ′ of the plurality of molded products 1 ′. Thus, the density D ₂ ′ when the boundary between the molded parts 2 ′ and 3 ′ substantially matches the planned position on the design is predicted, and the interpolation value of this density D ₂ ′ and the set density D _{2 of the} mass-produced product are predicted. The correction molding pressure ΔP ₂ can also be calculated from the difference between the _two . The reason why the correction injection amount is not calculated directly from the density difference (D ₂ ′ −D ₂ ) is that the relationship between density and molding pressure differs depending on the blending of urethane raw materials. That is, by calculating the corrected molding pressure ΔP ₂ at the injection time difference Δt from the density difference (D ₂ ′ −D ₂ ), any type of urethane stock solution is used as the second urethane stock solution U _2. (Ie, even if the polyurethane foam molded product 1 is manufactured using a urethane stock solution having a different composition from the urethane stock solution used to produce the prototype 1 ', for example), this corrected molding pressure ΔP ₂ Therefore, it becomes possible to obtain the corrected injection amount of the _second urethane stock solution U2.

With respect to several injection time differences Δt (6 seconds, 15 seconds, 20 seconds and 25 seconds in the reference example), the correction molding pressure ΔP ₂ is obtained by the above procedure, respectively, and the injection time difference Δt and the correction molding as shown in FIG. A graph showing the relationship with the pressure ΔP ₂ is obtained.

[Discussion]
This experiment according to the injection time difference Delta] t, the correction molding pressure [Delta] P ₂ was found to be determined.

DESCRIPTION OF SYMBOLS 1 Polyurethane foam molded product 2 1st polyurethane foam molded part 3 2nd polyurethane foam molded part 10 Foam mold 11 Lower mold 12 Upper mold 13 1st molding space 14 2nd molding space 15 1st injection | pouring Part 16 2nd injection | pouring part U ₁ 1st urethane undiluted solution U ₂ 1st urethane undiluted solution BL Planned boundary position of the 1st forming part and the 2nd forming part

Claims (3)

Polyurethane foam having two or more polyurethane foam molding parts having different physical properties or characteristics by injecting two or more types of urethane stock solutions capable of molding polyurethane foams having different physical properties or characteristics into a foaming mold and foaming. A method for producing a polyurethane foam molded product for integrally molding a molded product,
In the method for producing a polyurethane foam molded product, each urethane stock solution is injected into a foam molding die with a predetermined time difference and foamed.
When it is assumed that each urethane stock solution is injected into the foam molding die at the same time, the injection amount of each urethane stock solution having the same predetermined molding pressure is obtained in any polyurethane foam molding part at the time of molding. Is the reference injection amount of each urethane stock solution,
The larger the predetermined time difference is,
a) The injection amount of the urethane stock solution to be injected later is made larger than the reference injection amount.
b) The injection amount of the urethane stock solution injected first is less than the reference injection amount.
In addition to correcting the injection amount consisting of at least one of the above, each urethane stock solution was molded into the foam molding mold with a predetermined time difference and foamed, and was molded with the urethane stock solution previously injected. Each urethane raw material that makes it possible to push back the boundary between the molded part and the molded part molded with the urethane stock solution injected later to the designed boundary position by the expansion force of the urethane stock solution injected later. The molding pressure of
A method for producing a polyurethane foam molded article , wherein the injection amount correction is performed based on a difference between the molding pressure thus determined and the predetermined molding pressure .   In Claim 1, in the said predetermined | prescribed molding pressure, hardness is inject | poured by inject | pouring into the said foaming metal mold | die two or more types of urethane stock solutions which can shape | mold the polyurethane foam with the same hardness and different densities. A method for producing a polyurethane foam molded article, comprising integrally molding a polyurethane foam molded article having two or more polyurethane foam molded parts having the same density and different densities.   3. The reference injection amount of each urethane stock solution is set based on the density of the polyurethane foam molded by each urethane stock solution at the predetermined molding pressure and the design volume of each polyurethane foam molding part. A method for producing a polyurethane foam molded article.

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