JP5426227B2 - Method for producing polyurethane foam - Google Patents

Description

  The present invention relates to a method for producing a polyurethane foam, and more particularly, to a method for producing a polyurethane foam having high moldability and low shrinkage using timed pressure release (TPR).

In the production of a polyurethane foam using a reactive type, closed cells are more easily obtained than open cells, and high-temperature gas is contained in the bubbles. In the process of cooling the polyurethane foam, the pressure of the gas in the air bubbles may cause the polyurethane foam to shrink and become unusable as a product.
In order to prevent such shrinkage, it is necessary to perform manual compression or compression (crushing) by mechanical means such as a roller immediately after taking out from the mold.

However, manual compression requires time and labor, and the entire foam cannot be uniformly compressed, which may result in a product with a non-uniform structure. On the other hand, mechanical compression using rollers or the like is simpler than manual compression, but still requires a certain amount of work time, and cannot be applied to frame members such as seat pads for automobile seats. There was a case.
Therefore, as a method for solving these problems, a technique for releasing pressure by opening a mold in a polyurethane foam molding process has been proposed (see Patent Document 1), and releasing pressure by opening the mold and maintaining a constant pressure. The technique to hold | maintain is proposed (refer patent document 2).
The timed pressure release (hereinafter referred to as “TPR”) disclosed in Patent Documents 1 and 2 eliminates the need for compression (crushing) using a mechanical method such as a conventional roller, reduces shrinkage, and reduces dimensional change. It is an effective technique to suppress.

By the way, in the molding of urethane foam, in order to improve the moldability, it is important to use a composition that increases the ratio of closed cells. Specifically, a method of using a propylene glycol-ethylene glycol copolymer having a low molecular weight and a high content ratio of ethylene oxide (EO), or a method of increasing the amount of foaming agent used is employed.
However, when the composition is such that the closed cell ratio is high, there is a problem that the shrinkage becomes large in the production of the polyurethane foam.

JP 60-101010 A JP-A-8-258056

As described above, TPR is an effective method for producing a polyurethane foam, but the timing of depressurization, the degree of depressurization, the time of depressurization, etc. depend on the experience of a skilled worker, Moreover, it changes according to the foam material to be used, and it has been difficult to always manufacture under optimum conditions.
In particular, when using a polyurethane foam material blended so as to increase the closed cell ratio, it is important to determine the optimum production conditions for TPR.
Under such circumstances, an object of the present invention is to determine an optimum TPR condition according to the polyurethane foam material to be used and to provide a method for efficiently producing a polyurethane foam.

The present inventors set the optimum conditions for TPR by setting these within a specific range in relation to the gel time of the polyurethane foam material used, the elapsed time from the introduction of the polyurethane foam material, and the degree of depressurization. It has been found that the above problems can be solved easily. The present invention has been completed based on such findings.
That is, the present invention is a method for producing a polyurethane foam comprising a step of introducing a polyurethane foam material into a cavity formed in a mold and a step of foaming and molding the polyurethane foam material. In the molding step, the pressure in the mold is released so as to satisfy the following formulas (1) and (2).
(1) 0.005 ≦ Y <0.05
(2) 0.1X-0.15 <Y <0.18X-0.22
(X: Elapsed time (seconds) from introduction of polyurethane foam material divided by gel time (seconds), Y: Pressure drop in mold (MPa))

  ADVANTAGE OF THE INVENTION According to this invention, the optimal condition of TPR according to the polyurethane foam material to be used can be determined, and the method of manufacturing a polyurethane foam efficiently can be provided.

The production method of the present invention includes a step of introducing a polyurethane foam material into a cavity formed in a mold, and a step of foaming and molding the polyurethane foam material. The pressure is depressurized so as to satisfy the following expressions (1) and (2).
(1) 0.005 ≦ Y <0.05
(2) 0.1X-0.15 <Y <0.18X-0.22

In the above formulas (1) and (2), X represents the elapsed time (seconds) from the introduction of the polyurethane foam material (hereinafter sometimes simply referred to as “elapsed time (seconds)”) gel time (seconds). ), Ie, X = elapsed time (seconds) / gel time (seconds). Y represents the pressure drop (MPa) in the mold.
Here, the introduction of the polyurethane foam material is to introduce the polyurethane foam material into the cavity formed in the mold. Usually, at this time, the temperature of the mold is the temperature of the material. Is maintained at the temperature at which the material reacts and foams, meaning the same as at the beginning of foaming of the material. In addition, regarding gel time, in the present invention, after the start of stirring and mixing of the polyisocyanate component and the polyol component, which is a polyurethane foam material, the time when the stirred raw material turns white and foaming starts is cream time (foaming start time), foam The time for penetrating the needle and pulling the thread is defined as gel time (gelation time), and the time when foaming is finished in appearance is defined as rise time (foaming end time).

  In the present invention, in the step of foaming and molding the polyurethane foam material, part of the expansion gas in the mold is released from the mold to release the pressure. Specifically, the depressurization is performed by opening the mold, and the pressure drop in the mold at this time is Y, and the pressure after opening the mold from the pressure before opening the mold Is the difference (MPa).

In the above formula (1), if Y is less than 0.005, the effect of TPR cannot be obtained, and the resulting foam has a high shrinkage rate. On the other hand, if Y is 0.05 or more, the pressure in the mold is too low, and the foam is deformed.
Moreover, in said Formula (2), when Y is smaller than the value calculated by 0.1X-0.15, reaction will be inadequate and foam will collapse and a foam will not be obtained. On the other hand, when Y exceeds the value calculated by 0.18X−0.22, the shrinkage rate of the obtained foam becomes large.

  Next, the polyurethane foam material that can be used in the present invention will be described. In the present invention, materials usually used for producing polyurethane foam can be used. Specifically, (A) a polyisocyanate component, (B) a polyol component, (C) a blowing agent, and (D) a catalyst. And (E) obtained by foaming a compounded liquid containing a foam stabilizer. Hereinafter, each component will be described in detail.

((A) polyisocyanate component)
As the polyisocyanate component, various known polyfunctional aliphatic, alicyclic and aromatic isocyanates can be used. For example, tolylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, triphenyl diisocyanate, xylene diisocyanate, polymethylene polyphenylene polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, orthotoluidine diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, etc. These may be used alone or in combination of two or more.
Among them, in the present invention, it is preferable to contain tolylene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI) from the viewpoints of reactivity, physical properties, and safety.

  Here, although the compounding quantity of (A) component is not restrict | limited in particular, It is preferable that it is 90-120 mass parts with respect to 100 mass parts of all the polyol components. When the blending amount of the component (A) is 90 parts by mass or more, there is no problem of insufficient strength or poor foaming, and dimensional stability is also improved. On the other hand, when it is 120 parts by mass or less, a low-density polyurethane foam is obtained, and the brittleness at a low temperature becomes good. From the above viewpoint, the blending amount of the component (A) is more preferably in the range of 100 to 115 parts by mass with respect to 100 parts by mass of all polyol components.

  Further, the proportion of the component (A) in the blended liquid (when two or more isocyanates are used in combination, the ratio of the total amount in the blended liquid) is the isocyanate equivalent (active hydrogen in the blended liquid). When the amount (mole) is 100, the molar ratio of isocyanate groups in the blended solution is preferably in the range of 25 to 250. When the isocyanate equivalent is 25 or more, foaming and curing are performed, and when it is 250 or less, the density can be reduced. From the above viewpoint, the isocyanate equivalent is more preferably in the range of 50 to 120.

((B) polyol component)
Examples of the polyol component include polyether polyol, polymer polyol, and polyester polyol.
Although it does not specifically limit as a polyether polyol, The polyether polyol obtained by the ring-opening polymerization of alkylene oxide from a reactive viewpoint is suitable. Examples of such alkylene oxides include propylene oxide (PO) and ethylene oxide (EO). These may be used alone or in combination of two or more.
As the polyether polyol, the PO homopolymer, the EO homopolymer, and the polyether polyol obtained by copolymerization of PO and EO can be used. The copolymerization may be random copolymerization or block copolymerization.

In the present invention, from the standpoint of obtaining a polyurethane foam having good moldability, a blending with a high ratio of closed cells is preferably selected. For that purpose, it is preferable to use a polyether polyol. It is preferable to use a propylene glycol-ethylene glycol copolymer having a low molecular weight and a high ethylene oxide (EO) content ratio. More specifically, the number average molecular weight is preferably 6000 or less, more preferably 5000 or less, and particularly preferably 4500 or less. Further, the content ratio of EO is preferably 25 mol% or less, more preferably 20 mol% or less, and particularly preferably 10 to 18 mol%.
In the present invention, the number average molecular weight is a value calculated as a polystyrene conversion value by the GPC method, and the hydroxyl value is a value measured in accordance with JIS K1557.
Examples of the polymerization initiator include pentaerythritol, glycerin, ethylenediamine, Mannich, tolylenediamine, and sucrose. These polymerization initiators may be used alone or in combination of two or more.

  As a polyol component in this invention, the hydroxyl value in all the polyol components is 20-1000, Preferably it is 30-500 from the viewpoint of coexistence of the reaction rate of urethane foaming, and the dynamic characteristic of a foam.

Moreover, it is preferable to use a polymer polyol from the point which can suppress a dimensional change and the foam excellent in a moldability is obtained.
In this invention, it is preferable to contain 5 mass% or more of polymer polyol in a polyol component, and the foam which can suppress a dimensional change and was excellent in the moldability is obtained. From the above viewpoint, the content of the polymer polyol in the polyol component is preferably 10% by mass or more.
On the other hand, when the content of the polymer polyol in the polyol component is excessively large, the stability of the compounded liquid may be deteriorated or the reactivity may be lowered. Therefore, the content of the polymer polyol in the polyol component is The range of 10-70 mass% is preferable, and the range of 15-50 mass% is more preferable.

  Examples of the polymer polyol include a polymer polyol obtained by graft copolymerizing a polyether component with a polymer component such as polystyrene, polyacrylonitrile, or acrylonitrile-styrene copolymer. The alkylene oxide used as a raw material for the polyether polyol (polyalkylene oxide) used here preferably contains propylene oxide, and particularly preferably contains propylene oxide alone or contains both propylene oxide and ethylene oxide. The proportion of the graft polymer component as described above in the polymer polyol is usually 5 to 50% by mass.

Next, examples of the polyester polyol include aliphatic dicarboxylic acids having 4 to 20 carbon atoms such as adipic acid, suberic acid, sebacic acid, and brassic acid, terephthalic acid, and isophthalic acid as an acid component, and carbon such as ethylene glycol. The polyester polyol which uses ether glycols, such as the aliphatic diol of several 1-6, diethylene glycol, and a dipropylene glycol, etc. as a polyol component (alcohol component) can be mentioned. When it is desired to impart flame retardancy, it is preferable to add a polyester polyol.
In particular, phthalic acid polyesters based on phthalic acid other than phthalic anhydride (o-phthalic acid), that is, m-phthalic acid (isophthalic acid) and / or p-phthalic acid (terephthalic acid) and derivatives thereof. Use of a polyol is preferable from the viewpoint that flame retardancy can be improved. This is because a foam obtained from a polyol using phthalic acid (m, p-phthalic acid) having higher cohesive energy is difficult to burn.

  The hydroxyl value of such a phthalic acid-based polyester polyol, preferably m, p-phthalic acid-based polyester polyol, is 100 to 400 mgKOH / g, and the viscosity is 500 to 1500 mPa · s. The phthalic polyester polyol preferably has a p-phthalic acid content of 40 to 80% by mass. When the p-phthalic acid content in the phthalic polyester polyol is 40% by mass or more, sufficient flame retardancy is obtained, and when it is 80% by mass or less, sufficient pot life is obtained.

((C) foaming agent)
The foaming agent is not particularly limited, and chlorofluorocarbon foaming agents such as dichloromonofluoroethane and hydrofluorocarbon that have been used in the past can also be used. It is preferred to use water rather than these problematic foaming agents. Since water uses carbon dioxide gas produced by reaction with polyisocyanate, there is no environmental problem.
The blending amount of water as a foaming agent is not particularly limited as long as the effects of the present invention are achieved, but is usually in the range of 1 to 10 parts by weight, and 3 to 8 parts by weight with respect to 100 parts by weight of the polyol component. The range of is more preferable. When the water content is 1 part by mass or more, a sufficient foaming ratio is obtained, and when it is 10 parts by mass or less, sufficient dimensional stability of the polyurethane foam is obtained. A low boiling point compound such as methylene chloride or monofluorinated trichloromethane can be used in combination with water.

((D) Catalyst)
As the catalyst used in the present invention, an organic acid bismuth salt and / or an amine compound is preferably used. In the present invention, it is preferable not to use lead as a catalyst. By not using lead, hydrolysis of the polyester polyol can be prevented and the storage stability of the blended liquid can be improved.
Further, as other catalysts that can be used in combination with the organic acid bismuth salt and / or the amine compound, a potassium salt catalyst, a piperazine catalyst, or the like can be used. These catalyst components that can be used in combination can be used alone or in combination of two or more.

Examples of the organic acid bismuth salt include bismuth salts of alicyclic organic acids such as abietic acid, neoabietic acid, d-pimalic acid, iso-d-pimalic acid, podocarpic acid; benzoic acid, cinnamic acid, p -Bismuth salts of aromatic organic acids such as oxycinnamic acid; fatty acid bismuth salts of 8 to 20 carbon atoms such as octylic acid, 2-ethylhexylic acid, neodecanoic acid, neododecanoic acid, and the like. Of these, octylic acid, 2-ethylhexylic acid, and neodecanoic acid are preferably used from the viewpoint of maintaining reactivity. In addition, these organic acid bismuth salts may be used alone or in combination of two or more.
The compounding amount of the organic acid bismuth salt is not particularly limited, but is usually 0.1 to 5 parts by mass with respect to 100 parts by mass of the total polyol. When the amount is 0.1 parts by mass or more, there is sufficient reaction activity, and foaming is sufficiently performed. On the other hand, if it is 5 parts by mass or less, insufficient foaming due to the reaction being too early will not occur. From the above points, the blending amount of the organic acid bismuth salt with respect to 100 parts by mass of the total polyol is more preferably in the range of 0.5 to 3 parts by mass.

Next, examples of the amine compound include bis (3-dimethylaminopropyl) -N, N-dimethylpropanamine, tetramethylhexamethylenediamine, pentamethyldiethylenetriamine, dimethylcyclohexylamine, and bis- (dimethylaminoethyl) ether. , Tetramethylpropylenediamine, trimethylaminoethylpiperazine, tetramethylethylenediamine, dimethylbenzylamine, methylmorpholine, ethylmorpholine, triethylenediamine, 1-methylimidazole, 1-isobutyl-2-methylimidazole, 1,2-dimethylimidazole , N, N, N′-trimethylaminoethylethanolamine, and the like. Of these, tetramethylhexamethylenediamine, pentamethyldiethylenetriamine, bis (3-dimethylaminopropyl) -N, N-dimethylpropanamine and the like are preferably used from the viewpoint of reaction activity (balance between resinification and foaming). These amine compounds may be used alone or in combination of two or more.
As a compounding quantity of an amine compound, it is 0.5-5 mass parts normally with respect to 100 mass parts of all the polyols. When the amount is 0.5 parts by mass or more, a sufficient reaction rate is obtained, and foaming is sufficiently performed. On the other hand, if it is 5 parts by mass or less, insufficient foaming due to the reaction being too early will not occur. From the above points, the compounding amount of the amine compound with respect to 100 parts by mass of the total polyol is preferably 1 to 4 parts by mass, more preferably 3 to 4 parts by mass.

  Next, as the piperazine-based catalyst, piperazine, N, N, N-trimethylaminoethylpiperazine (TOYOCAT-NP, Caorizer No. 8) or the like can be used. As the potassium salt catalyst, potassium octylate, potassium acetate or the like can be used. These catalysts may be used individually by 1 type, and may mix and use 2 or more types.

((E) foam stabilizer)
The foam stabilizer used in the present invention is not particularly limited as long as it is usually used for polyurethane foam. That is, a general-purpose thing can be used as a thing for polyurethane foaming moldings, for example, silicone type foam stabilizers, such as various siloxane-polyether block copolymers, can be used.
As a compounding quantity of the foam stabilizer in a polyurethane foam undiluted | stock solution, it is 0.1-5 mass parts normally with respect to 100 mass parts of polyols of the said (A) component, It is preferable to set it as 0.3-3 mass parts especially. Even if it exceeds 5 parts by mass, there is no particular problem in performance, but the cost increases, and if it is less than 0.1 parts by mass, the stirrability of the polyol component and the isocyanate component decreases, and the intended urethane foam may not be obtained. Yes

The compounded liquid in the present invention can contain a flame retardant.
As the flame retardant, a general-purpose flame retardant can be used, and examples thereof include non-halogen phosphates, halogen-containing phosphates, non-halogen condensed phosphates, and halogen-containing condensed phosphates. Of these, the use of flame retardants mainly composed of non-halogen phosphate esters keeps the viscosity of the blended solution low, improves stirring efficiency, improves the homogeneity of the resulting molded product, and is applied to the spray method Is preferable from the standpoint of performing the process more easily.

Examples of the non-halogen phosphate include trimethyl phosphate, triethyl phosphate, tributyl phosphate, triisobutyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate. And cresyl di-2,6-xylenyl phosphate. Examples of the halogen-containing phosphate ester include tris (chloropropyl) phosphate, tris (dichloropropyl) phosphate, tris (tribromoneopentyl) phosphate, and the like. These may be used alone or in combination of two or more.
Moreover, as a compounding quantity of a flame retardant, it is 5-50 mass parts normally with respect to 100 mass parts of all the polyol components, Preferably it is 10-40 mass parts.

  In addition, the compounding liquid of the present invention appropriately contains a crosslinking agent, a colorant, a filler, an antioxidant, an ultraviolet absorber, a light stabilizer, a conductive material such as carbon black, an antibacterial agent, and the like as necessary. can do.

The solution viscosity of the compounded liquid of the present invention is usually 100 to 500 mPa · s, preferably 150 to 450 mPa · s, as the viscosity (liquid temperature 20 ° C.) measured in accordance with JIS K1557. If the solution viscosity deviates from the above range, the apparatus used when using the conventional polyurethane compounding liquid in the spray method may not be used as it is. On the other hand, an excessively high viscosity is not preferable because it tends to lead to deterioration in workability, deterioration in stirring efficiency, and consequently reduction in homogeneity of the obtained foamed molded article.
Moreover, in this invention, it is preferable to adjust pH immediately after the mixing | blending of a compounding liquid to 9 or less, Preferably it is 8-9. By setting the pH of the blended liquid to 9 or less, particularly 8 to 9, decomposition of the polyester polyol can be prevented, and the storage stability of the blended liquid can be improved.

Although it does not specifically limit as a compounding method of the compounding liquid in this invention, The polyol composition which consists of each component other than the said (A) polyisocyanate component is prepared, and it mixes with (A) component after that.
The polyol composition is prepared by blending the (D) catalyst with the (B) polyol component, and then (E) the foam stabilizer, difficult from the viewpoint of bringing water and the catalyst into contact as much as possible. It is preferable to blend a flame retardant and other components, and finally blend the water (C) which is a foaming component.

  The rigid polyurethane foam of the present invention preferably has a closed cell ratio of 10 to 65% by volume. When the closed cell ratio is 10% by volume or more, sufficient foam strength can be obtained, and the standard value shown in JIS A9526 can be satisfied. On the other hand, when it is 65% by volume or less, the dimensional stability of the foam is not impaired, and shrinkage is suppressed.

The rigid polyurethane foam of the present invention preferably has a settling rate of 4.5% or less. The settling rate correlates with the closed cell rate, and the smaller the value, the higher the closed cell rate. That is, blending with a low settling rate is preferable because of good moldability.
The lower limit of the settling rate is not particularly limited, but if the closed cell rate is too high, the foam tends to shrink. From the above viewpoint, the settling rate is preferably in the range of 1 to 4.5%.
Here, settling refers to a phenomenon in which the molded foam sinks after reaching the maximum height, and the settling rate is calculated from the following equation.
Settling rate (%) = [(MN) / M] × 100
However, in the formula, M means the maximum height (mm) of the foam, and N means the height (mm) when the foam is depressed.

  The rigid polyurethane foam of the present invention is useful as a vehicle seat pad, can suppress wobbling, and can suppress the inclination of the seat during cornering. In addition, it is possible to reduce car sickness and improve sitting comfort.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Production Examples 1 to 5 (Preparation of polyurethane foam material)
In accordance with the formulation shown in Table 1, a formulation liquid (polyurethane foam material) was prepared. In the preparation, a polyol composition comprising each component other than (A) the polyisocyanate component was prepared, and then (A) the polyisocyanate component was blended. The polyol composition was prepared by first mixing (B) the polyol component and (D) catalyst, then blending (E) the foam stabilizer, and finally (C) mixing water. In addition, as the polyisocyanate component (A), a mixture of 2,6-tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) (TDI: MDI = 80: 20, isocyanate equivalent 90) was used. The isocyanate equivalent was adjusted to 90.
Freely foam the compounded liquid obtained in each production example, foam height N (mm) at the time of 180 seconds after the start of the reaction, foam maximum height M (mm) between the start of the reaction and 180 seconds Measured and calculated by the above formula ([(MN) / M] × 100). The amount of the compounded solution used was 250 g in Production Examples 1 to 4 and 220 g in Production Example 5.

* 1 Polyol A: Polyether polyol (general-purpose polyol, “Sannik KC710” manufactured by Sanyo Chemical Industries, Ltd., weight average molecular weight 5000, hydroxyl value 34 mgKOH / g, ethylene oxide (EO) content 15 mol%, propylene oxide (PO ) Content 85 mol%)
* 2 Polyol B: Polyether polyol (highly active polyol, “Sannik KC725” manufactured by Sanyo Chemical Industries, Ltd., weight average molecular weight 5000, hydroxyl value 34 mgKOH / g, ethylene oxide (EO) content 20 mol%, propylene oxide ( PO) content 80 mol%),
* 3 Polyol C: Polyether polyol (low molecular weight polyol, “Sanix KC731” manufactured by Sanyo Chemical Industries, Ltd., weight average molecular weight 4000, hydroxyl value 42 mgKOH / g, ethylene oxide (EO) content 18 mol%, propylene oxide ( PO) content 82 mol%)
* 4 Polyol D: Polymer polyol (polystyrene / polyacrylonitrile copolymer (polyacrylonitrile; 34% by mass, “SANNICS KC855” manufactured by Sanyo Chemical Industries, Ltd.)

* 5 Catalyst A: Triethylenediamine (TEDA) (“L-33” manufactured by Tosoh Corporation)
* 6 Catalyst B: Amine-based catalyst (“TOYOCAT D-60” manufactured by Tosoh Corporation)
* 7 Catalyst C: Diethanolamine (Nippon Shokubai Co., Ltd.)
* 8 Foam stabilizer: “BY10-304” manufactured by Toray Dow Corning Co., Ltd.

Example 1
(Preparation of formulation liquid)
Using the blended liquid prepared in Production Example 4, three kinds of blended liquids having different gel times were prepared. The one with a gel time of 60 seconds was used as the mixture liquid A, the one with 65 seconds as the mixture liquid B, and the one with 70 seconds as the mixture liquid C.
(Manufacture of foam)
It was prepared by applying a wax release agent to a rectangular metal mold of 350 × 350 × 70 mm. The bottom of the movable mold, including the mold cavity, was placed over the airbag. The airbag is pressed against the movable mold to support the bottom of the mold, the mold is heated to 60 ° C., and about 250 g of the mixture liquids A to C (liquid temperature 25 ° C.) prepared in Production Example 4 are respectively applied to the mold. Then, the air bag was pressurized to 0.45 MPa and the mold was closed.
After a lapse of a certain time from the introduction of the blended solution, the pressure of the airbag was reduced to release the pressure. The amount of decrease in pressure in the mold (Y) is controlled by the degree of decrease in the pressure of the airbag. Specifically, the amount of decrease in pressure (Y) is in the range of 0.005 to 0.040 MPa. Data was taken at intervals of 0.005 MPa. Moreover, about the time to depressurize, the data of 5 second intervals were extract | collected according to each pressure fall part (Y) within the range after 75 second passage-125 second passage after introduction of a compounding liquid. Table 2 shows the results of arranging these data as values of Y, 0.1X−0.15, and 0.18X−0.22.
Here, the obtained foam was evaluated according to the following criteria.
(Evaluation criteria for foams)
a: a good foam was obtained b; a foam which was inferior to that of a but practically no problem was obtained c; a void was generated and the performance as a foam was not exhibited. d: There was a problem in dimensional stability due to large shrinkage

Reference Examples i to v , Comparative Examples 1 and 2 and Reference Examples 1 to 4
As shown in Table 3, a polyurethane foam is produced according to any of the following TPR conditions using the same method as described in Example 1 using the formulation liquids prepared in Production Examples 1 to 5. did. The gel time was adjusted to 65 seconds. The evaluation results and the physical properties of the produced foam are shown in Table 3. Moreover, as a reference example 1-4 , the result of having measured the physical-property value about the polyurethane foam manufactured by the conventional method which does not use TPR is described in Table 3. In addition, the evaluation criteria of a foam are the same as that of Example 1.
Condition I of TPR: 90 seconds after the introduction of the polyurethane foam material, the pressure of the airbag was reduced from 0.45 MPa to 0.30 MPa.
Condition II of TPR: 90 seconds after the introduction of the polyurethane foam material, the pressure of the airbag was reduced from 0.45 MPa to 0.20 MPa.
TPR condition III: 90 seconds after the introduction of the polyurethane foam material, the pressure of the airbag was reduced from 0.45 MPa to 0.10 MPa.
(Method for evaluating physical properties)
Closed cell property: Measured using a closed cell measuring device in accordance with ASTM D2856.
25% hardness: The load required for compressing 25% of the urethane foam was evaluated.

  According to the production method of the present invention, it is possible to determine the optimum TPR conditions according to the polyurethane foam material to be used, and to efficiently produce the polyurethane foam. In particular, in order to improve moldability, when using a polyurethane foam material blended so as to increase the closed cell ratio, there is a problem that shrinkage increases in the production of polyurethane foam, It is very useful to determine the optimum production conditions of TPR by the method.

Claims (3)

A method for producing a polyurethane foam, comprising a step of introducing a polyurethane foam material into a cavity formed in a mold and a step of foaming and molding the polyurethane foam material. the pressure of the inner and depressurization so as to satisfy the equation (1) and (2) below, polyurethane foams materials, (a) a polyisocyanate component, (B) a polyol component, (C) a blowing agent, (D) It comprises a compounded solution containing a catalyst and (E) a foam stabilizer. (B) The polyol component contains a polyether polyol of 50% by mass or more, and the polyether polyol is a propylene glycol-ethylene glycol co-polymer. It is made of a polymer, the ethylene glycol content ratio is 25 mol% or less, the number average molecular weight is 5000 or less, and (D) the catalyst is amine-based. Ones, and the and the production method of the polyurethane foam settling rate is not more than 4.5% of the amount thereof is characterized 0.5-5 parts by der Rukoto per 100 parts by weight of all the polyols.
(1) 0.005 ≦ Y <0.05
(2) 0.1X-0.15 <Y <0.18X-0.22
(X: Elapsed time (seconds) from introduction of polyurethane foam material divided by gel time (seconds), Y: Pressure drop in mold (MPa)) The method for producing a polyurethane foam according to claim 1 , wherein the (B) polyol component further contains 5% by mass or more of a polymer polyol. (C) The method for producing a polyurethane foam according to claim 1 or 2 , wherein the foaming agent is water.