JP3831149B2 - Process for producing polyurethane reaction injection molded foam - Google Patents

Description

【００３５】
実施例１〜３
参考例１と同様に調製し、３０℃に加温したそれぞれのポリオール混合物（炭酸ガス１８時間供給：実施例１（圧力１ｋｇ／ｃｍ²）、実施例２（圧力２ｋｇ／ｃｍ²）、実施例３（圧力３ｋｇ／ｃｍ²））１００部と、イソシアネート（スミジュールＰＣ（住友バイエルウレタン社製：変性ピュアーMDI））４４．２部を高圧ポリウレタン発泡機（Ｈｅｎｎｅｃｋｅ社製：ＨＫ−１６５）のタンクに入れ、ＮＣＯインデックス１０５、吐出量２００ｇ／秒、混合圧力１６０ｋｇ／ｃｍ²で、６０℃に加温したハンドル形状のスチール製型に、ポリウレタン原料を注入した。型に原料を注入してから３０秒後に脱型し、ハンドル成形品を得た。成形条件を表２に示す。得られた成形品の物性を表３に示す。
【００３６】
実施例４〜５
参考例１に示したポリオール混合物１００部に、炭酸ガスを溶解させることなく、３気圧の乾燥空気でタンクシールし、３０℃に加温し、参考例２のそれぞれのイソシアネート（炭素ガス１８時間供給：実施例４（圧力２ｋｇ／ｃｍ²）、実施例５（圧力３ｋｇ／ｃｍ²））４４．２部を実施例１と同様にハンドル成形品を得た。成形条件を表２に示す。得られた成形品の評価結果を表３に示す。
【００３７】
【表２】

¹⁾ＣＯ₂溶解量は、反応混合物（イソシアネート＋ポリオール混合物の合計）の重量に基づく。
【００３８】
【表３】

【００３９】
比較例１
参考例１と同様のポリオール混合物に、炭酸ガスを溶解させることなく、代わりに水を０．５部添加した。実施例１と同様のイソシアネート（スミジュールＰＣ）に炭酸ガスを溶解させることなく、ポリオール混合物と反応させ、実施例１と同様にハンドル成形品を得た。成形条件は表４に示す。成形品の評価結果を表５に示す。
【００４０】
比較例２
参考例１と同様のポリオール混合物を高圧ポリウレタン発泡機のタンクに入れ、減圧弁のついた液化炭酸ガスボンベをつなぎ、攪拌をしながら５気圧に調圧した炭酸ガスを供給した。４時間後にポリオール混合物を抜き取り密度を測定すると０．０９g/cm³で、炭酸ガスの溶解量はポリオール混合物の重量に基づいて２．０％であった。このポリオール混合物と、実施例１と同様のイソシアネート（スミジュールＰＣ）に炭酸ガスを溶解させることなく、反応させ、実施例１と同様にハンドル成形品を得た。成形条件を表４に示す。成形品の評価結果を表５に示す。
【００４１】
【表４】

【００４２】
【表５】

【００４３】
【発明の効果】
本発明の製造法にしたがって得られたインテグラルスキン構造を有するポリウレタン発泡体は、短時間で脱型しても、成形品の膨れが非常に小さい。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a polyurethane foam having an integral skin structure and a density of 0.2 to 0.8 g / cm ³ . The polyurethane foam having an integral skin structure has excellent tactile sensation and elasticity, and is used for automobile interior parts such as armrests, steering wheels, change knobs and the like.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, chlorofluorocarbon, especially trichlorofluoromethane (CFC-11) has been mainly used as a foaming agent, but it is known that it destroys the ozone layer in the atmosphere, and its use is prohibited. In recent years, from the viewpoint of cost and environment, water foaming, which is foamed using water, has been mainly used.
[0003]
However, when a polyurethane foam having a density of 0.2 to 0.8 g / cm ³ is formed by water foaming, it is very difficult to form an integral skin (Urethane Technology p32: Oct./Nov. 1994). ). In order to control the reaction between water and isocyanate, a technique for adding water in the form of a hydrated salt (Japanese Patent Laid-Open No. 6-1820), using a large amount of a catalyst and a crosslinking agent after increasing the viscosity of the reaction raw material, A technique for improving reactivity (Japanese Patent Laid-Open No. 5-59146, etc.) has been reported. However, by increasing the reactivity, the flowability is lowered, the density becomes too high, or the thick part is blistered and it is necessary to lengthen the demolding time.
[0004]
Conventionally, skin formation of integral skin foam is considered to be performed due to the difference in foaming reaction due to the temperature difference between the surface layer in contact with the mold during molding of the molded product and the inner core (Plastics: Vol.24 , No8, P-118), froth foaming injecting foamy liquid was considered disadvantageous for skin formation.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve this problem, carbon dioxide gas is not compared with the conventional carbon dioxide gas generated from the reaction of water and isocyanate (JP-A-5-339338, etc.), but carbon dioxide gas is compared with polyisocyanate or polyol mixture in advance. By using the dissolved carbon dioxide gas as a foaming agent, it is possible to obtain a molded product with a skin layer in one molding, so-called integral skin molding is possible. I found something. In the present invention, when the reaction mixture is discharged into a mold from a so-called high-pressure polyurethane foaming machine, the carbon dioxide gas is released from the reaction mixture and the reaction mixture is discharged in the form of foam.
[0006]
As a result of the present invention, by using dissolved carbon dioxide gas as a foaming agent, a molded product having a skin layer can be obtained by one molding, and a polyurethane foam having an integral skin structure can be obtained for 60 seconds. Even if the mold is removed in a very short period of time, the molded product is less likely to swell compared to conventional water foaming, and the productivity of this type of molded product can be greatly improved.
[0007]
Carbon dioxide gas has the same effect when applied to either an isocyanate or a polyol mixture. In the present invention for injecting a foam-like liquid, dissolving a large amount of carbon dioxide gas exceeding 1% by weight in the raw material results in injecting an unstable unreacted foam of the reaction mixture into the mold. Bubble collapse occurs, and as a result, void troubles that lead to molding defects occur. In order to avoid this trouble and to ensure skin formation, the reaction mixture reacts relatively fast so that the reaction rise time of the foam ends, that is, the so-called rise time is 40 seconds or less. It must be adjusted to have sex.
[0008]
The present invention relates to an integral by a reaction injection molding process from a polyol mixture comprising (i) a polyisocyanate and (ii) a polyol, a catalyst, and optionally a chain extender, a reinforcing material and other auxiliaries. A method for producing a polyurethane foam having a skin structure and a density of 0.2 to 0.8 g / cm ³ , comprising:
a) At least one of the polyisocyanate and polyol mixture comprises a foaming agent, the foaming agent comprising 0.05 to 1.0% by weight of carbon dioxide gas based on the total weight of the polyisocyanate and polyol mixture. Become
b) Provided is a method for producing a polyurethane foam, wherein the reactivity of a polyisocyanate and a polyol mixture is adjusted so that the time for completion of the reaction start of the foam is 40 seconds or less.
[0009]
As polyisocyanate used in the present invention, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, these polyisocyanates were urethane-modified, allophanate-modified, carbodiimide-modified, isocyanurate-modified. There are modified polyisocyanates and mixtures thereof.
[0010]
Examples of polyols include hydroxyl group-containing compounds such as propylene glycol, diethylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, and sucrose, amino group and hydroxyl group compounds such as triethanolamine and diethanolamine, or ethylenediamine and diaminotoluene. Polyether polyol having 2 to 6 hydroxyl groups in a molecule obtained by adding an alkylene oxide such as ethylene oxide or propylene oxide to an amino group-containing compound, and having an average hydroxyl equivalent weight of 100 to 3000, or a vinyl compound in these polyether polyols Polymer polyols obtained by addition polymerization of are used.
[0011]
Also, polyester polyols obtained from polycarboxylic acids and low molecular weight hydroxyl group-containing compounds, polycarbonate polyols obtained by ring-opening polymerization of caprolactone, amination of hydroxyl groups in polyether polyols, or hydrolysis of isocyanate polyol prepolymers of polyether polyols It is also possible to use a polyether polyamine having an average active hydrogen equivalent of 100 to 3000.
[0012]
The hydroxyl value of the polyol may be 561-22 mg KOH / g, for example 112-28 mg KOH / g.
[0013]
Examples of the catalyst include triethylenediamine, pentamethyldiethylenetriamine, 1,8diazabicyclo-5,4,0-undecene-7, dimethylaminoethanol, tetramethylethylenediamine, dimethylbenzylamine, tetramethylhexamethylenediamine, bis (2-dimethylamino). Tertiary amines such as ethyl) ether and organometallic compounds such as dibutyltin dilaurate, tin octoate, and dibutyltin diacetate are used.
[0014]
By changing the amount of catalyst and the type of catalyst, the reactivity of the polyisocyanate and polyol mixture is adjusted so that the rise time of the foam finishes, that is, the rise time is 40 seconds or less, for example, 10 to 40 seconds. It is necessary to be.
[0015]
The blowing agent dissolves carbon dioxide gas (for example, liquefied carbon dioxide gas) in the polyisocyanate and / or polyol mixture, and the dissolved amount is 0.05 to 1.0% by weight based on the total weight of the polyisocyanate and polyol mixture. It is. When the amount is less than 0.05%, foaming is insufficient. When the amount is more than 1%, voids increase due to excess carbon dioxide gas, and the foam surface is affected. Also, an amine compound carbonate or an organic acid such as formic acid may be used in combination as an auxiliary foaming agent. To dissolve carbon dioxide gas in the polyisocyanate and / or polyol mixture, stirred 1-5 kg / cm ^2, for example 2 to 50 hours under a carbon dioxide pressure of 2~5kg / cm ^2, for example 5 to 20 hours starting material You can save it.
[0016]
It is also possible to put liquid carbon dioxide gas directly into the high pressure line of the molding machine while measuring with a pump. It is not desirable in the present invention for the purpose of skin formation to use water which is frequently used in this type of molding as a foaming agent. If the water content in the polyol mixture exceeds 0.3%, the degree of skin formation is significantly impaired. It is preferable that water is not substantially contained in the polyol mixture.
[0017]
As the chain extender, a dihydric alcohol having a molecular weight of 62 to 300, such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, Divalent amines such as diethyltoluenediamine, t-butyltoluenediamine, diethyldiaminobenzene, triethyldiaminobenzene, tetraethyldiaminodiphenylmethane and the like are used as necessary, and polyether polyols obtained by adding alkylene oxide to these are also used. Examples of the chain extender are described in JP-B-54-17359, JP-A-57-74325, JP-B-63-47726, JP-B-1-34527 and the like.
The amount of the chain extender may be 3 to 10 parts by weight, for example 4 to 7 parts by weight, based on 100 parts by weight of the polyol.
[0018]
Examples of the reinforcing material include glassy, inorganic, mineral and other fibers such as milled glass fiber, wollastonite fiber, processed mineral fiber or flakes such as mica and glass flakes, which are used as necessary. It is also possible to set a glass mat, glass cloth or the like in a mold in advance and then inject a polyurethane raw material to obtain a foam.
The amount of the reinforcing material may be 20 parts by weight or less, for example, 5 to 10 parts by weight with respect to 100 parts by weight of the polyol.
[0019]
Other aids include cell stabilizers such as silicone foam stabilizers, surfactants, weathering agents such as antioxidants, UV absorbers, stabilizers such as 2,6-di-t-butyl-4-methyl. Phenol, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4-hydroxyphenyl) propionate] methane, a colorant, and the like are used as necessary. In the present invention, it is desirable to use a bubble stabilizer in order to keep the initial bubbles of the reaction mixture stable.
The amount of the other auxiliary agent may be 15 parts by weight or less, for example, 2 to 10 parts by weight with respect to 100 parts by weight of the polyol.
[0020]
For the production of polyurethane foam by the reaction injection molding method (RIM method), a reaction injection molding machine such as a high pressure polyurethane foaming machine manufactured by Hennecke or a high pressure polyurethane foaming machine for R-RIM manufactured by Polyurethane Engineering is used.
[0021]
In the present invention, the isocyanate index [(ratio of the equivalent of isocyanate group of polyisocyanate to the equivalent of active hydrogen in polyol mixture) × 100] may be 90 to 120, particularly 100 to 110.
[0022]
The present invention, without using a chlorofluorocarbon as a blowing agent, density 0.2 to 0.8 g / cm ³ with integral skin structure, for example, to produce a 0.4 to 0.8 g / cm ³ Polyurethane foam Can do.
[0023]
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. Parts and% are parts by weight and% by weight.
[0024]
The physical properties were measured as follows.
Rise time (time when form rise ends)
From the injection head of the high-pressure polyurethane foaming machine, the mixed liquid discharged at 200 g / s for 1 second is put out into a 1 L polyethylene cup, and the rise time is measured.
[0025]
Swelling at the time of demolding for 30 seconds The inter-arm dimension after one day of the demolded product for 30 seconds is measured and evaluated in comparison with the standard dimension (mold cavity dimension).
5: More than -1% from the reference dimension 4: -0.5 to 1% from the reference dimension
3: 0 to -0.5% from the standard dimension
2: +0.5 to 0% from standard dimension
1: More than + 0.5% from the standard dimension.
It injected 2 seconds flowability <br/> discharge rate 200 g / s, but to obtain a molded article of 400 g, to evaluate the presence or absence and burr amount of underfill terminals of the molded article.
5: No missing meat, burr amount exceeds 100 g 4: No missing meat, burr amount 50-100 g
3: No lack of meat, burr amount is 20-50g
2: The terminal has a small cutout (1-5 mm) and the burr amount is less than 20 g. 1: The terminal has a large cutout (5 mm or more) and the burr amount is less than 20 g.
Void Evaluation is based on the presence and diameter of voids.
5: None at all 4: None on the surface 3: There are voids with a diameter of less than 1 mm 2: There are voids with a diameter of 1 to 3 mm 1: There are voids with a diameter of more than 3 mm
Pinhole Evaluation is based on the presence and area of pinholes.
5: None at all 4: not seen with the naked eye 3: specific part (1 cm ² or less) slightly occurs 2: 1 slightly occurs in a specific portion (1 to 4 cm ^2): occurs several locations over a wide area [0029]
W line of the PL portion When the molded product tends to expand when the mold is opened, the edge of the mold may come into contact with the handle molded product along the parting line (PL). Evaluate the presence and extent of this line.
5: W-line does not occur even if the mold is removed in 20 to 25 seconds. W-line does not occur even if the mold is removed in 4:30 seconds. When the line is removed at 2:30 seconds, the W line is generated at less than half of the handle circumference. When the mold is removed at 1:30 seconds, the W line is generated at more than half of the handle circumference.
Skin formation The thickness of the non-foamed integral skin layer is measured and evaluated.
5: Thickness over 0.5 mm 4: Thickness 0.3-0.5 mm
3: Thickness 0.1-0.3mm
2: Less than 0.1 mm thick 1: Less than 0.1 mm thick skin layer is foamed.
Reference example 1
90 parts of a polyether polyol having a hydroxyl value of 28 mg KOH / g obtained by adding propylene oxide and ethylene oxide (weight ratio of propylene oxide and ethylene oxide 82:18) to glycerin and 6 parts of ethylene glycol, 1.2 parts of a 33% ethylene glycol solution of triethylenediamine Then, 0.02 part of dibutyltin dilaurate, 0.2 part of silicone foam stabilizer, 1.0 part of weathering agent and 1.8 parts of colorant were mixed to obtain 10 kg of a polyol mixture.
[0032]
This polyol mixture was placed in a tank of a high-pressure polyurethane foaming machine (Henecke Co., Ltd .: HK-165), connected to a liquefied carbon dioxide cylinder equipped with a pressure reducing valve, and carbon dioxide adjusted to 1 to 3 atm with stirring was supplied. . After 4 hours, 8 hours and 18 hours, the polyol mixture was withdrawn and the specific gravity was measured to examine the amount of carbon dioxide dissolved (%) based on the weight of the polyol mixture. The results are shown in Table 1.
[0033]
Reference example 2
Modified diphenylmethane diisocyanate (Sumijoule PC (manufactured by Sumitomo Bayer Urethane Co., Ltd .: Modified Pure MDI)) is placed in a tank of a high pressure polyurethane foaming machine, connected to a liquefied carbon dioxide gas cylinder with a pressure reducing valve, and stirred at 1 to 3 atm. The carbon dioxide gas decompressed was supplied. The amount of CO ₂ dissolved (%) based on the weight of isocyanate was examined. The results are shown in Table 1.
[0034]
[Table 1]

[0035]
Examples 1-3
Each polyol mixture prepared in the same manner as in Reference Example 1 and heated to 30 ° C. (supplied with carbon dioxide gas for 18 hours: Example 1 (pressure 1 kg / cm ² ), Example 2 (pressure 2 kg / cm ² ), Example 3 (pressure 3 kg / cm ² )) and 44.2 parts of isocyanate (Sumijoule PC (manufactured by Sumitomo Bayer Urethane Co., Ltd .: modified pure MDI)) tank of high pressure polyurethane foaming machine (manufactured by Hennecke: HK-165) The polyurethane raw material was poured into a handle-shaped steel mold heated to 60 ° C. with an NCO index of 105, a discharge rate of 200 g / sec, and a mixing pressure of 160 kg / cm ² . 30 seconds after injecting the raw material into the mold, the mold was removed to obtain a handle molded product. Table 2 shows the molding conditions. Table 3 shows the physical properties of the obtained molded article.
[0036]
Examples 4-5
Without dissolving carbon dioxide in 100 parts of the polyol mixture shown in Reference Example 1, the tank was sealed with 3 atmospheres of dry air, heated to 30 ° C., and each isocyanate of Reference Example 2 (carbon gas supplied for 18 hours) : Example 4 (pressure 2 kg / cm ² ), Example 5 (pressure 3 kg / cm ² )) 44.2 parts were obtained in the same manner as in Example 1 to obtain a handle molded product. Table 2 shows the molding conditions. Table 3 shows the evaluation results of the obtained molded product.
[0037]
[Table 2]

^{1) The} amount of CO ₂ dissolved is based on the weight of the reaction mixture (total of isocyanate + polyol mixture).
[0038]
[Table 3]

[0039]
Comparative Example 1
Instead of dissolving carbon dioxide in the same polyol mixture as in Reference Example 1, 0.5 parts of water was added instead. A handle molding was obtained in the same manner as in Example 1 by reacting with the polyol mixture without dissolving carbon dioxide in the same isocyanate (Sumidule PC) as in Example 1. The molding conditions are shown in Table 4. Table 5 shows the evaluation results of the molded products.
[0040]
Comparative Example 2
The same polyol mixture as in Reference Example 1 was placed in a tank of a high-pressure polyurethane foaming machine, connected to a liquefied carbon dioxide cylinder equipped with a pressure reducing valve, and carbon dioxide adjusted to 5 atm with stirring was supplied. The polyol mixture was withdrawn after 4 hours and the density was measured to be 0.09 g / cm ³ , and the amount of carbon dioxide dissolved was 2.0% based on the weight of the polyol mixture. This polyol mixture was reacted with the same isocyanate (Sumidule PC) as in Example 1 without dissolving carbon dioxide, and a handle molded product was obtained in the same manner as in Example 1. Table 4 shows the molding conditions. Table 5 shows the evaluation results of the molded products.
[0041]
[Table 4]

[0042]
[Table 5]

[0043]
【The invention's effect】
Even if the polyurethane foam having an integral skin structure obtained according to the production method of the present invention is demolded in a short time, the swelling of the molded product is very small.

Claims (1)

It has an integral skin structure by a reaction injection molding method from a polyol mixture comprising (i) a polyisocyanate and (ii) a polyol, a catalyst, and optionally a chain extender, a reinforcing material and other auxiliary agents. A method for producing a polyurethane foam having a density of 0.2 to 0.8 g / cm ³ , comprising:
a) At least one of the polyisocyanate and polyol mixture comprises a foaming agent, the foaming agent comprising 0.05 to 1.0% by weight of carbon dioxide gas based on the total weight of the polyisocyanate and polyol mixture. Carbon dioxide gas is dissolved in the polyisocyanate and / or polyol mixture,
b) A process for producing a polyurethane foam, characterized in that the reactivity of the polyisocyanate and polyol mixture is adjusted so that the time to complete the reaction rise of the foam is 40 seconds or less.