JP5451143B2 - Production method of urethane foam - Google Patents

Description

  The present invention relates to a method for producing urethane foam, and more particularly to a method for producing urethane foam with high work efficiency.

As a method for producing a urethane foam having a predetermined product shape, a molding method for forming a urethane foam by injecting a urethane foam raw material into a mold and foaming it is frequently used.
In general, the higher the heating temperature, the more the reaction is promoted. For example, in Patent Document 1, a molding die is partitioned into a plurality of parts via a heat insulating material, and a temperature adjusting means is provided for each of the partitioned parts. A mold for adjusting the temperature has been proposed (see Patent Document 1 and Claim 4). It is said that by using this mold, it is possible to easily produce foams having different hardness at each part (see Patent Document 1, paragraph 0014).

  On the other hand, the higher the heating temperature is, the more the reaction is promoted. However, in view of demolding workability, it cannot be increased without limitation. For this reason, the temperature has been set so as to achieve both reactivity and workability. However, at the conventional set temperature, in terms of reactivity, the method of applying heat is not efficient and there is a loss in energy. At the same time, the initial resin strength of the urethane foam may be low. In addition, stickiness may occur on the molding surface, and there may be a case where a hand mark or tear occurs at the time of demolding, and the resin may be deformed by the roller at the time of crash. Furthermore, since the resin reaction of urethane is slow, there are disadvantages such as low productivity.

JP 2007-216441 A

  In view of the above-described problems, an object of the present invention is to provide a method for producing a urethane foam with improved resin moldability and strength and high work efficiency.

The present inventor has found that the above-described problems can be solved by performing specific temperature increase and temperature decrease in the urethane foam production method. The present invention has been completed based on such findings.
That is, the present invention
[1] In a method for producing urethane foam in which a urethane foam raw material is injected into a mold and heated to react to form a foamed molded article and demolded, the temperature of the mold at the time of raw material injection is 60. It is ± 5 ° C., the temperature is raised from this temperature, the temperature is lowered at 40 to 60% of the time from the start of the temperature rise to the end of the reaction , and the maximum temperature of the molding die is 10 to Urethane foam production method characterized by being 20 ° C higher ,
[2] The method for producing a urethane foam according to [1] above, wherein the temperature of the mold during demolding is 60 ± 5 ° C., and [3] the time until the temperature of the mold reaches the maximum temperature is increased. The method for producing a urethane foam according to the above [1] or [2] , which is after 30% of the time from the start of temperature to the end of the reaction,
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of urethane foam with high work efficiency and energy efficiency can be provided. Further, according to the production method of the present invention, the initial resin strength is improved, no hand marks are formed, and no blurring occurs. Also, deformation after a crash is reduced.

It is the schematic which shows a heating method.

In the method for producing a urethane foam of the present invention, a urethane foam raw material is injected into a mold and heated to cause a reaction to proceed to form a foamed molded product, which is then demolded. Here, the temperature of the molding die at the time of raw material injection is 60 ± 5 ° C., the temperature is raised from the temperature, and the temperature is lowered at 40 to 60% of the time from the temperature raising start to the reaction end. .
The demolding temperature is preferably 60 ± 5 ° C. At this temperature, the work efficiency of the demolding worker is high.

In the present invention, the maximum temperature of the mold is appropriately determined according to the raw material of the urethane foam to be used, but is preferably 10 to 20 ° C. higher than the temperature at the time of raw material injection. More specifically, it is preferably set in the range of 70 to 85 ° C. When the maximum temperature of the mold is within this range, the closed cell property is difficult to increase, and cell roughness on the resin surface due to melting of the release agent can be avoided.
Moreover, it is preferable that the time until the temperature of the mold reaches the maximum temperature is after 30% of the time from the start of the temperature rise to the end of the reaction. That is, for example, when the time from the start of temperature increase to the end of the reaction is 240 seconds, it is preferable to reach the maximum temperature after 72 seconds from the start of temperature increase. By controlling the time to reach the maximum temperature in this manner, cell roughness on the resin surface due to melting of the release agent can be avoided.

There is no restriction | limiting in particular about the heating method in this invention, There exist the method using a heat medium, such as water and oil, the method using an electric furnace, etc. Therefore, there are various methods for raising and lowering the temperature depending on the heating method.
Hereinafter, for example, a case where water is used as a heat medium will be described with reference to FIG.
FIG. 1 is a schematic view showing an example of raising and lowering the temperature of the mold 1 by switching between high-temperature water and low-temperature water. The high temperature water and the low temperature water are respectively controlled by the high temperature side temperature controller 4 and the low temperature side temperature controller 5, and in the example shown in FIG. 1, the high temperature water is controlled to 110 ° C. and the low temperature water is controlled to 60 ° C.

A heat medium flow path is provided in the mold, and when the urethane foam raw material is injected, low-temperature water (60 ° C.) is allowed to flow, and the mold temperature is controlled to 60 ± 5 ° C. More specifically, the low-temperature water coming out of the low-temperature side temperature controller 5 passes through the switching valve 6, is flowed to the mold 1, and is heated. The low temperature water coming out of the mold passes through the switching valve 7 and returns to the low temperature side temperature controller 5.
Next, when the raw material is injected, the switching valves 6 and 7 are switched, and the high-temperature water (110 ° C.) is mixed with the low-temperature water or completely switched to the high-temperature water, and the high-temperature water is allowed to flow. Thus, the temperature of a shaping | molding die is raised by distribute | circulating high temperature water. In addition, by adjusting the mixing ratio of the high temperature water and the low temperature water, the temperature of the heat medium can be controlled and the temperature of the mold can be controlled. Specifically, it is preferable that the maximum temperature of the mold and the time to reach the maximum temperature are controlled so as to be within the above-mentioned preferable range.

Next, the temperature is lowered at 40 to 60% of the time from the start of the temperature rise to the end of the reaction. For example, when the time from the start of temperature increase to the end of the reaction is 240 seconds, the temperature decrease is started between 96 seconds after the start of temperature increase and 144 seconds after the start of temperature increase. The method of lowering the temperature is because the switching valves 6 and 7 are switched again and low-temperature water is allowed to flow.
In this way, by controlling the temperature in the mold, the temperature is somewhat low during the raw material injection and demolding operations, so that the operation is easy, while the reaction temperature can be increased during the reaction. Therefore, good properties of the molded product can be obtained, energy efficiency can be increased, and manufacturing efficiency can be improved.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. In each example and comparative example, an experiment with 50 samples was performed and evaluated.

Reference example 1
(1) Preparation of foaming stock solution The foaming stock solution was prepared using the material shown below.
(A) Polyol component (A-1) Polyether polyol (Asahi Glass Urethane Co., Ltd. general purpose high elasticity polyol “Exenol EL828”, number of functional groups 3, number average molecular weight 5,000, hydroxyl value 34 mg KOH / g) 50 parts by mass (A-2) Polymer polyol (manufactured by Sanyo Chemical Industries, Ltd., polystyrene / polyacrylonitrile copolymer 34 mass% “Sanix KC855”)
(A-3) Crosslinker ("EL555" manufactured by Asahi Glass Urethane Co., Ltd., 6 functional groups, hydroxyl value 550 mg KOH / g) 5 parts by mass (B) polyisocyanate component (B-1) tolylene diisocyanate (TDI, Mitsui Chemicals) 28.2 parts by mass (B-2) diphenylmethane diisocyanate (MDI, “MR-200HR” manufactured by Nippon Polyurethane Co., Ltd.); 7.0 parts by mass (C) foaming agent 2.5 parts by weight of water (D) As catalyst, (D-1) 0.3 parts by weight of triethylenediamine (“L-33” manufactured by Tosoh Corporation), (D-2) bis (dimethylaminoethyl) ether (Tosoh Corporation “TOYOCAT-ET”) 0.3 parts by mass In addition to the above, as a foam stabilizer, a silicone-based foam stabilizer (Toray Dow Corning “SZ1325B” 0.5 In the preparation of the amount part, (B) a polyol mixture composed of each component other than the polyisocyanate component was prepared, and then (B) the polyisocyanate component was blended. The component and (D) catalyst were mixed, then a foam stabilizer and a crosslinking agent were blended, and finally (C) water was mixed to prepare the polyurethane foam stock solution at 30 ° C.

(2) Manufacture of urethane foam (vehicle seat pad) Using a device as shown in FIG. 1, low temperature water (58 ° C.) was circulated and the molding die was controlled at 60 ± 5 ° C. The stock solution prepared in (1) above was injected immediately under the atmospheric pressure. After the injection, the switching valves 6 and 7 were switched, a part of the high-temperature water (110 ° C.) was circulated, and the temperature increase was started immediately. The flow rate of the hot water was adjusted so that the maximum temperature of the mold reached 65 ° C. and the time required to reach 65 ° C. was 120 seconds.
Next, since the time from the start of temperature increase to the end of the reaction was 240 seconds, when 120 seconds had elapsed from the start of temperature increase, the switching valves 6 and 7 were switched again to distribute only low-temperature water. The temperature of the mold at the time when 240 seconds had elapsed from the start of the temperature increase (at the end of the reaction) was 58 ° C.
The urethane foam (vehicle seat pad) produced in this way was evaluated for the degree of burr stickiness (relative comparison), the presence or absence of hand marks on the product surface, and the presence or absence of product tearing. Moreover, the crush roller whose roller space | interval is 10 mm was passed, and the thickness after a crash was measured. The thickness before the crash was 66 mm. The results are shown in Table 1.

Example 1
In Reference Example 1, the flow rate of high-temperature water was adjusted in the same manner as in Reference Example 1 except that the time until the maximum temperature of the mold reached 70 ° C. and 70 ° C. was 120 seconds. Obtained. The results evaluated in the same manner as in Reference Example 1 are shown in Table 1. The thickness before the crash was 66 mm.

Comparative Example 1
In Reference Example 1, a urethane foam was obtained in the same manner as in Reference Example 1 except that the reaction was performed at a constant molding mold temperature of 58 ° C. The results evaluated in the same manner as in Reference Example 1 are shown in Table 1. The thickness before the crash was 66 mm.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of urethane foam with high work efficiency and energy efficiency can be provided. According to the production method of the present invention, the initial resin strength is improved, no hand marks are formed, and no blurring occurs. Also, deformation after a crash is reduced. The urethane foam obtained by this production method is used for various applications, and is particularly suitable for a vehicle seat pad.

1. Mold 2. Upper mold 3. Lower mold 4. 4. High temperature side temperature controller 6. Low temperature side temperature controller 6 and 7. Switching valve

Claims (3)

In a method for producing urethane foam in which a urethane foam raw material is injected into a mold and heated to react to form a foamed molded article and demolded, the temperature of the mold at the time of raw material injection is 60 ± 5 ° C. The temperature is raised from this temperature, the temperature is lowered at 40 to 60% of the time from the start of the temperature rise to the end of the reaction , and the maximum temperature of the mold is 10 to 20 ° C. higher than the temperature at the time of raw material injection A method for producing urethane foam, characterized in that:   The method for producing a urethane foam according to claim 1, wherein the temperature of the mold at the time of demolding is 60 ± 5 ° C. The method for producing a urethane foam according to claim 1 or 2 , wherein the time until the temperature of the mold reaches the maximum temperature is after 30% of the time from the start of the temperature rise to the end of the reaction.

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