JPH04214712A - Production of molded product of urethane foam - Google Patents

Abstract

PURPOSE:To obtain a molded product of an urethane foam suitable as interior trim parts, etc., of automobiles, etc., by forming a high-density surface layer on the surface based on a difference in gasifying reaction caused by chemical reaction of isocyanates with a foaming agent using a specific catalyst. CONSTITUTION:A reaction solution composed of (A) isocyanates, (B) polyols and (C) a catalyst composed of one or more selected from (C1) morpholine-based compounds [e.g. 4(N,N-dimethylaminopropyl)-2,6-dimethylmorpholine], (C2) piperazine-based compounds (e.g. methylhydroxypiperazine), (C3) imidazole-based compounds [e.g. 1,1'-(oxydiethylene)bis(2-methyl-imidazole)], (C4) triazone-based compounds and (C5) amidine-based compounds (organic acid salts) or optional combination of the components (C1) to (C5), (D) a foaming agent (e.g. water) and (E) a foaming assistant at 15-30 deg.C temperature is injected into a metallic mold at 15-40 deg.C in one shot to afford the objective molded product of urethane foam having a high-density surface layer on the surface.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a urethane foam molded product,
More specifically, the present invention relates to a method for manufacturing urethane foam molded products used as interior parts of automobiles, ships, etc., and components of furniture, etc., particularly urethane foam molded products having a high-density surface layer.

[Prior Art] Urethane foam molded products having a high-density surface layer have conventionally been made using low boiling point chlorofluorocarbons, such as CFC-1.
It has been produced using 1 or CFC-113 as a blowing agent and 1,4-diazabicyclo(2,2,2)octane, dibutyltin dilaurate, etc. as a catalyst.

Specifically, the reaction heat accompanying the foaming of the urethane foam transfers to the mold, causing a temperature difference within the foamed resin body, causing a non-contamination on the high-density surface layer and the mold surface, which are the parts that come into contact with the mold. In order to form the contact intermediate layer into foam, CFC-11 and C, which are low boiling point solvents (foaming agents) that have already been mixed into the urethane foam stock solution and are homogeneously compatible with each other, are used.
Due to the difference in vaporization rate of FC-113 and the further progress of the reaction,
When the foam is filled into the mold and the foaming pressure inside the mold increases, the gas that has already been gasified and captured as foam condenses again on the surface layer that is in contact with the mold, causing the resin layer to react. is absorbed (that is, re-compatible) into the mold, forming a thicker high-density layer in the surface layer that contacts the inner surface of the mold. In this state, the resin liquid rapidly gels (i.e., the polymerization reaction of the resin liquid progresses to increase the molecular weight, i.e., polymerization causes the viscosity to rapidly increase, and eventually loses its fluidity and solidifies, hereinafter simply referred to as "gelation"). ) to fix the high-density surface layer and the relatively low-density foam layer in the center, and form the foam core (core part) with the same stock solution in one injection foaming operation.
and a high-density surface layer at the same time. As described above, when producing a urethane foam molded product having a high-density surface layer, CFC-11, CFC-113, etc. have been used.

However, today, halogenated hydrocarbon blowing agents containing fluorine and chlorine, such as CFC-11, CFC-113, H.CFC-123 and H.CFC-141b, are destroying the ozone layer in the stratosphere. , more harmful ultraviolet rays that have been absorbed by the ozone layer reach the earth's surface, causing mutations, inactivation, and damage to genes and cells, leading to an increase in skin cancer, changes in the ecosystem, and atmospheric temperature. There are concerns that the rise in carbon dioxide emissions will have a serious negative impact on the greenhouse effect, etc. For this reason, CFC-11 and C are used as blowing agents.
There is a desire for a technology for manufacturing urethane foam molded products having a high-density surface layer while reducing or eliminating the use of FC-113 and the like. For example, possible technologies include: ■ Manufacturing technology using other low-boiling point solvents; ■ Technology that substitutes with a high-density surface layer by thickening the coating film using the in-mold coating method; ■ So-called gas using dry air or nitrogen gas Manufacturing technology that uses loading in combination is being researched with the premise of mass production.

From a manufacturing perspective, all of the above technologies require heat treatment or depressurization treatment to exhaust the gas in the resulting product foam, are toxic or rusty, and require a great deal of expense to modify equipment. There was a problem that it required On the other hand, from a product perspective, there are some drawbacks such as the resulting high-density surface layer not being sufficiently formed, so it is not a sufficient solution technology.

[Problem to be solved by the invention] Regarding the above technology, the present inventors used CFC as a blowing agent.
As a result of intensive research to develop a method for producing urethane foam molded products with a high-density surface layer, the amount of low-boiling solvents such as -11 and CFC-113 can be significantly reduced or even eliminated. By using a substance that generates gas when chemically reacting with isocyanates as a kind of catalyst and blowing agent, it is possible to produce CFC-11 and CFC-113, which physically generate gas due to the heat of chemical reaction. This led to the invention of a method for manufacturing urethane foam molded products that significantly reduces or does not use low-boiling solvents.

That is, an object of the present invention is to significantly reduce or eliminate the use of halogenated hydrocarbon foaming agents containing fluorine and chlorine in a method for manufacturing urethane foam molded articles having a high-density surface layer. The object of the present invention is to provide a manufacturing method that can be manufactured without the need for manufacturing. More specifically, by using a specified catalyst and a substance that generates gas when chemically reacted with isocyanates, halogenated hydrocarbon foaming agents containing fluorine and chlorine are not used. Another object of the present invention is to provide a method for producing a urethane foam molded article having a high-density surface layer by using a small amount of the material.

[Means for Solving the Problems] A method for manufacturing a urethane foam molded product according to the present invention is configured as follows. That is, a method for manufacturing a urethane foam molded product in which a resin liquid containing isocyanates, polyols, catalysts, blowing agents, auxiliary agents, etc. is injected into a mold using a one-shot machine to form a high-density surface layer on the surface. It can be produced using a predetermined catalyst without using a halogenated hydrocarbon blowing agent containing fluorine or chlorine, or with a small amount of blowing agent. The catalyst is at least one selected from (1) a morpholine compound, (2) a piperazine compound, (3) an imidazole compound, (4) a triazine compound, (5) an amidine compound or an organic acid salt of an amidine compound. using one, or (1), (2
), (3), (4), and (5) based on the difference in gas generation due to the difference in chemical reaction between the isocyanates and the blowing agent, that is, the difference in gasification reaction. , obtained by forming a high-density surface layer on the surface. At this time, water can be used as a foaming agent, or a water-absorbed resin can be used.

At this time, it is preferable that the temperature of the mold is in the range of 15°C to 40°C and the temperature of the resin liquid is in the range of 15°C to 30°C.

(1) Morpholine compounds include 4(N,N-dimethylaminopropyl)2,6-dimethylmorpholine, N-
Examples include methylmorpholine and N-ethylmorpholine, and commercially available products can be used. For example, U
-CAT2044 (manufactured by Sun-Apro Co., Ltd.), Kaolizer No. 21 and no. 22 (manufactured by Kao Corporation). These morpholine compounds can be used alone or in combination with triazine, imidazole, or amidine catalysts.

(2) Examples of piperazine compounds include methylhydroxypiperazine, trimethylinoethylpiperazine, bis[2-(4-methylpiperazinyl)ethyl]ether, and 1-methyl-4'-(dimethylaminoethyl)piperazine. , commercially available ones can be used. For example, To
yoCAT-HP, ToyoCAT-HPW, Toyo
CAT-NP (manufactured by Tosoh Corporation), U-CAT2050
(manufactured by Sun-Apro Co., Ltd.), Kaolizer No. 8 (manufactured by Kao Corporation). These piperazine compounds can be used alone or in combination with triazine, imidazole, or amidine catalysts.

(3) Among the above-mentioned catalysts used in the present invention, imidazole ether compounds which are imidazole-based catalysts are those described in Japanese Patent Application No. 158919/1988, 1,
Examples include 1'-(oxydiethylene)bis(2-methyl-imidazole) and 1,1'-(oxydiethylene)bis(imidazole). Further, as imidazole catalysts, 1-position substituted imidazole compounds include 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, 1,2-dimethylimidazole, 1-ethyl-2-methylimidazole, 1-propyl -2-methylimidazole, 1-aminoethyl-2-methylimidazole, and other imidazole compounds include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-ethylimidazole, and the like. Among these imidazole compounds, 1,
2-dimethylimidazole, 1,1'-(oxydiethylene)bis(2-methyl-imidazole), 2-ethyl-4-methylimidazole, 2-ethylimidazole,
2-methylimidazole, etc., and commercially available ones can be used except for 1,1'-(oxydiethylene)bis(2-methyl-imidazole). For example, U-CAT2026
, U-CAT2030 (manufactured by Sun-Apro Co., Ltd.), Curesol 2MZ, Curesol 2E4MZ, Curesol 2EZ (manufactured by Shikoku Kasei Kogyo Co., Ltd.), and the like. These imidazole compounds can be used alone, in combination of two or more, or in combination with triazine-based, amidine-based, organic acid salts of amidine-based compounds, morpholine-based, pyridine-based catalysts, and the like.

(4) As a triazine compound, N,N',N''-tris(dimethylaminopropyl)hexahydro-S-
Triazine, organic acid metal salt of N,N',N''-tris(dimethylaminopropyl)hexahydro-S-triazine, N,N',N''-tris(dimethylaminopropyl)hexahydro-S-triazine and N ,N′,N
It is preferable to use at least one selected from a mixture of "-tris(dimethylaminopropyl)hexahydro-S-triazine and an organic acid salt. As these triazine catalysts, commercially available ones can be used. For example, Pol
Examples include yCAT41 and PolyCAT42 (manufactured by Air Products, sold by Sun-Apro Co., Ltd.).

(5) Among the above catalysts, as an amidine compound, 1
, 8-diazabicyclo(5,4,0)undecene-7 and its organic acid salts can be commercially available. for example,
DBU, U-CAT SA1, U manufactured by Sun-Apro Co., Ltd.
-CAT SA102, U-CAT SA106, U-
CAT SA109, V-CAT SA506, U-C
AT SA603 is mentioned. In addition, 1-position substituted imidazole compounds and 1,8-diazabicyclo(5,4,
0) The ratio of Undensen-7 or its organic acid salt is usually 1:0.5 to 1:1.5, preferably 1:0.7
~1:1.2.

In the production of semi-rigid urethane foam having a high-density surface layer, the amount of the catalyst used in the present invention is usually 0.3 to 3.0 parts by weight, preferably 0.6 to 3.0 parts by weight, based on 100 parts by weight of the polyol component. It is 1.8 parts by weight.

Moreover, the above catalyst in the present invention can be used in combination with conventionally known catalysts.

As a known catalyst, (1) As an amine catalyst, 1,4 diazabicyclo(
2,2,2) Octane, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N-tris(dimethylaminopropyl)amine, N-methyl-N,N-
Bis(dimethylaminopropyl)amine and N-methyldicyclohexylamine(2)tin-based catalysts include dibutyltin diurate, stannath octate, and the like.

When a conventionally known catalyst is used in combination, the ratio of the catalyst of the present invention to the conventionally known catalyst is usually 1:0.1 to 1:1.5, preferably 1:1 in the case of an amine catalyst. 0.3~
1:0.7, and for tin-based catalysts, it is usually 1:0.7.
0.01-1:0.1, preferably 1:0.01-1
:0.05.

To describe the present invention in more detail, the above-mentioned catalyst and a substance that generates gas when chemically reacted with isocyanates are used, and the temperature setting of the mold used in combination is different from that of the conventional C.
Resin uniformly stirred and mixed at a temperature of 15-40°C, preferably 20°C ± 5°C, which is significantly lower than the 45-60°C in the production method using a low boiling point solvent such as FC-11. Inject the liquid into the mold. In addition, when forming a semi-rigid high-density surface layer as a urethane foam molded product, the temperature is 15°C.
A resin liquid whose temperature is controlled to 30° C. to 30° C., preferably 20° C.±3° C. and which is stirred and mixed uniformly is injected into a mold. In this way, foaming of the resin liquid is delayed in the surface layer that is in contact with the inner wall surface of the mold, and foaming and gelation are caused in the intermediate layer that is not in contact with the inner wall surface of the mold due to heat accumulation due to an exothermic reaction. This results in a so-called high overpack state (
In a state where foaming is further suppressed in the surface layer that contacts the inner wall surface of the mold where foaming is delayed,
Rapid gelation can occur to form a dense surface layer.

Moreover, when it is desired to make a high-density surface layer into a thin layer, the adjustment temperature of the resin liquid (urethane stock solution) used may be increased from 20°C±30°C to 30°C. Furthermore, in order to reduce the density of the high-density surface layer, the mold temperature may also be raised from 20°C ± 5°C to 40°C, and the conditions for obtaining the desired high-density surface layer may be selected through testing in advance. .

It goes without saying that these conditions and the amount of gas generating substance (foaming agent) added may also be changed.

The formation process of a urethane foam molded product that forms a high-density surface layer on the surface is explained theoretically based on FIG. 1. Between time A and B, as shown by a1 and b1 or a2 and b2 in the figure, Fill the mold with foam liquid in the area where there is a foaming degree difference (i.e. foaming ratio difference or density difference) between the middle layer and the surface layer (
gelation based on polymerization (the viscosity of the resin liquid increases rapidly due to polymerization, i.e., polymerization due to the progress of the polymerization reaction of the resin liquid), as shown in the example gelation curve G.
A state where liquidity eventually disappeared. (hereinafter simply referred to as "gelation based on polymerization"), at time B1, the densities of the intermediate layer and the surface layer are fixed at a2 and b2, and the surface layer has a density lower than that of the intermediate layer. A high integral layer is formed.

In this way, the density difference between a1 and b1 and a2 and b2 in Fig. 1 is maintained, and the inside of the mold is filled with foam liquid at any density difference within this time interval A1 to B1. later,
What is necessary is to complete gelation based on polymerization. To be more specific, the time when the inside of the mold is filled with foamy liquid (full filling) by the reactive resin liquid (urethane stock solution) is the foaming degree of foaming curves a and b at elapsed time A1. Between the volumes corresponding to a1 and b1 and the volume of the void in the mold, the volume corresponding to [a0+(a1-a0)+(b1-a0)]=volume of the void in the mold is established. from the point in time.

Furthermore, if the desired elapsed time An is the interval from elapsed time A1 to B1, then the foaming degrees of foaming curves a and b are an and bn [a0+(an-a0)+(
bn-a0)] = Resin liquid (urethane stock solution) used so that the volume of the void in the entire mold is satisfied.
It can be said that it is sufficient to determine the amount of injection into the mold.

On the other hand, the timing of gelation of the foam liquid filled in the mold (total filling) is determined by adjusting the reaction of the compounded liquid in advance so that gelation based on polymerization is completed at a desired arbitrary density difference within the time interval An to B1. Just adjust the gender.

The density difference after the resin liquid (urethane stock solution) is injected into the mold is a1-b1, where A1 is the point in time when the voids in the mold are filled with the initial foaming of the resin liquid. Even after the elapsed time A1, the foaming of the intermediate layer continues to progress more rapidly than that of the surface layer due to heat accumulation based on the exothermic reaction.
The foaming pressure inside the mold increases rapidly, and the surface layer also transfers heat to the mold, which is pre-adjusted to a low temperature, and the foaming is suppressed to an unfoamed or low foaming state. .

In this state, if gelation based on polymerization of the foam liquid is completed at point Am in the section An to B1 in Figure 1, the density difference will be a
It becomes m-bm. If Am=B1, the densities are a2 and b2, the intermediate layer and the surface layer are fixed, and an integral layer having a higher density than the intermediate layer is formed in the surface layer.

All known polyols can be used in the present invention. That is, for example, alkylene oxides (e.g. ethylene oxide, propylene oxide, etc.), low molecular weight polyols (e.g. ethylene glycol, propylene glycol, glycerin, trimethylolpropane, triethanolamine, pentaerystol, sorbitol, sucrose, etc.) and polyamines (e.g. Ethylenediamine, diethylenetriamine, tolylenediamine,
xylylene diamine, piperazine, N-aminoalkylpiperazine, N-N dimethylaminoalkylamine, cyclohexylene diamine, etc.), polyether polyol and ethylenically unsaturated monomer (e.g. acrylonitrile, styrene, methyl methacrylate, butadiene, etc.) (e.g., U.S. Pat. No. 3,383,3
51), polycarboxylic acids (e.g. succinic acid, maleic acid, sebacic acid, adipic acid, fumaric acid, phthalic acid, dimer acid, etc.) and the above-mentioned low-molecular-weight polyols. Examples include polyester polyols.

Among these polyols, preferred for molding a semi-rigid urethane foam molded product having a high-density surface layer are polypropylene polyols added with polypropylene oxide such as di- or tri-functional propylene glycol, glycerin, and trimethylolpropane. These are polyether polyols with ethylene oxide added to the ends, and polymer polyols with acrylonitrile or vinylbenzene. These polyols can be used alone or in combination of two or more. In general, for 100 parts by weight of polyol components, 25 to 80 parts by weight of isocyanates, 2 to 20 parts by weight of crosslinking agent, 0.5 to 10 parts by weight of blowing agent, and 0.3 to 0.3 parts by weight of catalyst. 3.0 parts by weight can be used.

All known isocyanates can be used in the present invention. That is, for example, aromatic polyisocyanates (e.g., tolylene diisocyanate, diphenylmethane diisocyanate, etc.), aliphatic polyisocyanates (e.g., hexamethylene diisocyanate, isophorone diisocyanate, etc.), modified products thereof (e.g., partially carbodiimide or nurate modification, etc.), and polyesters thereof. Examples include prepolymers containing free isocyanate by reaction with functionally active hydrogen compounds. These isocyanates can be used alone or in a mixture of two or more.

The amount of isocyanates used in the present invention varies depending on the type of polyol, the type and amount of crosslinking agent added, the amount of blowing agent (gas generating substance) added, and the type of isocyanate. Ingredients 100
Usually 25 to 80 parts by weight, preferably 4 parts by weight
It can be manufactured by adjusting the amount to 5 to 70 parts by weight.

In the present invention, there are no particular restrictions on the blowing agent, ie, the substance that generates gas when reacted with isocyanates, but it is preferable to use water, which is easily available anywhere and is negligible in price. In particular, when water is used, water-absorbing resins such as so-called isobutylene and maleic anhydride copolymers (for example, KI Gel 201K manufactured by Kuraray Co., Ltd.) may be used.
-F2), vinyl acrylate alcohol copolymers (e.g. SP-520 manufactured by Sumitomo Chemical Co., Ltd.), and sodium acrylate polymers (e.g. NP-101 manufactured by Sumitomo Chemical Co., Ltd.).
0.5 to 10 parts by weight, preferably 0.5 to 5 parts by weight of fine powder such as 0.0 bulk powder) as an active ingredient based on the polyol component.
When added within the range of parts by weight, these resins absorb and adsorb water to swell and retain water, which retards the reaction with isocyanates, making it easier to form urethane foam molded products with a high-density surface layer. becomes. This is presumed to be due to the following reason. In other words, these superabsorbent resins are polymer electrolytes that can absorb water tens to thousands of times their own weight. This is thought to be due to the rapid absorption of water and formation of a hydrogel based on the resulting osmotic pressure and the affinity between water and the polymer electrolyte. Taking acrylic acid vinyl alcohol copolymer as an example, the chains of an ionic, water-soluble electrolyte polymer are loosely cross-linked, so the mechanism by which water is absorbed is that of a polymer electrolyte. When the acrylate phase swells, the polyvinyl alcohol phase is stretched and undergoes so-called oriented crystallization. This is presumed to be due to the formation of a composite structure in which the crystallized polyvinyl alcohol part supports the polyacrylate part in a water-absorbing state. Therefore, when using a water-absorbing resin together, the catalyst system is diluted with polyols, etc. as an independent third component system, in which the first component is an isocyanate component, the second component is a polyol component, water/water-absorbing resin, When the mixed components of the foam stabilizer, pigment, and crosslinking agent are homogeneously mixed and stirred at the time of injection, it is preferable to perform the addition, mixing, and stirring instantaneously.

Examples of the crosslinking agent used as an auxiliary agent in the present invention include amine-based low-molecular polyols such as triethanolamine and diethanolamine, and low-molecular polyols such as ethylene glycol, diethylene glycol, butalidiol, trimethylolpropane, and glycerin. These low molecular weight polyols can be used alone or in combination of two or more. The amount of crosslinking agent used in the present invention is:
Although it varies depending on the type of crosslinking agent, in the case of semi-rigid urethane foam molded products with a high-density surface layer, ordinary polyol 1
2 to 20 parts by weight, preferably 3 to 1 parts by weight per 00 parts by weight
It can be manufactured by setting the amount to 0 parts by weight.

In addition, in the production of the urethane foam molded product of the present invention, auxiliary agents such as emulsifiers, stabilizers, surfactants as cell regulators, fillers, colorants, and oxidation stabilizers may be used as necessary. It is. It goes without saying that a low boiling point solvent can also be used as the blowing agent.

In addition, conventionally known methods for manufacturing urethane molded products with a high-density surface layer are available, such as the so-called open method in which the mixed urethane resin liquid is injected into the mold with the upper lid of the mold open, and then the lid is immediately closed.・Mold method and closed mold method, in which the mixed urethane resin liquid is injected into the mold using a film gate or injection hole with the lid closed in advance, and the so-called reaction injection molding method. It can be manufactured.

[Effect of the invention] As mentioned above, the urethane foam molded product having a high-density surface layer is made of CFC-11, CFC-113 or H
・Fluorine such as CFC-123 and H・CFC-141b,
Since the production can be carried out with a significant reduction in the amount of chlorine-containing halogenated hydrocarbon-based blowing agents used or even without the use, environmental damage caused by the blowing agents can be prevented. Furthermore, the method of the present invention does not require heat treatment or vacuum treatment of the urethane foam molded product, unlike other manufacturing methods. Furthermore, there is no need to worry about toxicity or rust caused by chlorinated low boiling point solvents, and conventional equipment can be used.

As described above, according to the present invention, by using the above catalyst and water that generates gas when chemically reacted with polyisocyanates, CFC-11 is used as a blowing agent.
It is possible to provide a method for manufacturing a urethane foam molded product having a high-density surface layer, while significantly reducing or not using CFC-113 or the like.

[Margins below] [Examples] In order to better understand the present invention, specific examples will be described below along with comparative examples.

(Example 1) Trifunctional polyether polyol (Sumifen-3063; O manufactured by Sumitomo Bayer Urethane Co., Ltd.) was used as the polyol.
HV=28mgK-OH/g) 94g, 6g of ethylene glycol (1st grade reagent), 0.3g of silicone foam stabilizer (Nippon Unicar Co., Ltd. L-5305) as a foam stabilizer, and 1.95g of distilled water as a foaming agent. , and as a catalyst (1) U-
0.6g of CAT2044 and 0 of U-CAT SA1
．． 6g, (2) Kaolizer No. A mixture of 0.7 g of No. 21 and 0.7 g of U-CAT2030 was added thereto, and the temperature was controlled at 20° C. to prepare two types of mixed liquids. Crude MDI (manufactured by Mitsui Toatsu Chemical Co., Ltd., MDI-CR-
Add 64.3 g of 200) and immediately stir for 6 seconds with a homomixer to obtain a homogeneous mixed state. Effective space size for injection: 10mm thick x 16mm wide
0 mm x length 120 mm), and the upper lid was closed and pressed with a clamp to create a state capable of withstanding foaming pressure. After leaving it for 10 minutes, the upper lid was opened, the molded product was taken out, cut in the thickness direction, and the cross section was checked. As a result, the high-density surface layer with an average thickness of 1.5 mm and 1.3 mm, respectively, was in good condition. Been formed. It was a semi-rigid urethane foam molded product with a homogeneous fine cell structure. The properties of the obtained urethane foam molded product having a high-density surface layer were as shown in Table-1.

The reactivity of the liquid mixture used for injection was as shown in Table 2.

The molded product obtained in this example was a semi-rigid urethane foam molded product having a good high-density layer on the surface layer.

(Comparative example) As a comparative example, a conventionally used low boiling point blowing agent C
Using FC-11, the temperature of the mold was set to 20°C (Comparative Example 1)
and the case where the temperature was 55°C (Comparative Example 2).

As polyols, trifunctional polyol 3063 (manufactured by Sumitomo Bayer Urethane Co., Ltd.; OHV = 28 mg K-O
H/g) 94g and ethylene glycol (1st grade reagent) 6g
, Silicone foam stabilizer (Nippon Unicar Co., Ltd.) as a foam stabilizer
L-5305) 0.5g, low boiling point solvent C as a blowing agent
FC-11 (Asahi Flon-11 manufactured by Asahi Glass Co., Ltd.) 15
g, and 0.6 g of Dabco-33LV (manufactured by Sankyo Air Products Co., Ltd.) and 0.02 g of U-100 (manufactured by Nitto Kasei Co., Ltd.) as catalysts were added to prepare a mixed solution whose temperature was controlled at 20°C. Crude MDI (MDI-CR manufactured by Mitsui Toatsu Chemical Co., Ltd.), which was temperature-controlled at 20°C, was added to this as an isocyanate.
-200) was added and immediately stirred for 6 seconds using a homomixer to obtain a homogeneous mixed state. And in advance 5
The mixture was immediately poured into molds similar to those in Example 1 whose temperatures were controlled at 5° C. and 20° C., and the upper lids were closed and pressed with clamps to create a state capable of withstanding foaming pressure. After leaving it for 10 minutes, the upper lid was opened, the molded product was taken out, cut in the thickness direction, and the cross section was checked. When the mold temperature was 20°C in Comparative Example 1, the surface layer was sticky. Moreover, it was a defective product with a column-shaped cavity containing coarse air bubbles in the surface layer, and could not be used as a product. Also, comparative example 2
When the mold temperature was 55°C, the results were as shown in Table 3.

The reactivity of each liquid mixture used for injection was as shown in Table 4 below.

The product obtained by molding the mold at a temperature of 55°C is a semi-rigid urethane foam molded product with a high-density layer, and is a urethane foam molded product having a high-density surface layer on the surface layer, similar to the product of Example 1 according to the present invention. It was a quality product.

(Example 2) In the same manner as in Example 1 above, trifunctional polyether polyol (Sumifen-3063 manufactured by Sumitomo Bayer Urethane Co., Ltd.; OHV = 28 mgK-OH/g) was used as the polyol.
94 g, 6 g of ethylene glycol (1st grade reagent), and a silicone foam stabilizer (L-5 manufactured by Nippon Unicar Co., Ltd.) as a foam stabilizer.
305) 0.3 g, distilled water 1.95 g as a blowing agent, (1) PolyCAT42 (manufactured by Air Products Co., Ltd., sold by Sun-Apro Co., Ltd.) 1.2 g as a catalyst, (2) U
-0.5g of CAT2030 and ToyoCAT-NP
1.0g, (3) 0.5g of U-CAT2044 and 1.0g of ToyoCAT-HPW, (4) U-CAT
0.7g of 2050 and 0.8g of U-CAT2030
were added to each to prepare four types of mixed liquids whose temperature was controlled at 20°C. The same operations as in Example 1 above were performed on each of these. That is, crude MDI (MDI-C manufactured by Mitsui Toatsu Chemical Co., Ltd.) whose temperature was controlled at 20°C was used as an isocyanate.
Add 64.3g of R-200), stir immediately with a homomixer for 6 seconds to obtain a homogeneous mixture, and preheat at 20°C.
Immediately inject into an aluminum mold with a clamp (effective space size for injection: 10 mm thick x 160 mm wide x 120 mm long) equipped with a 20 mm thick top lid whose temperature is controlled to 20 mm, close the top lid, and press with a clamp. The condition was such that it could withstand foaming pressure. After leaving it for 10 minutes, the upper lid was opened, the molded product was taken out, cut in the thickness direction, and the cross section was confirmed. It was a semi-rigid urethane foam molded product having a homogeneous fine cell structure in which a high-density surface layer with an average thickness of 1.2 mm to 1.5 mm was formed in good condition. The properties of the obtained urethane foam molded product having a high-density front side in the surface layer were as shown in Table-5.

The reactivity of the liquid mixture used for injection was as shown in Table 6.

The molded product obtained in this example was a semi-rigid urethane foam molded product having a good high-density layer on the surface layer.

(Example 3) In this example, a product was produced by changing the catalyst in Example 2 as shown in Table 7(a) below, and otherwise operating under the same conditions. Cut this molded product in the thickness direction,
When the cross section was confirmed, the high-density surface layer as the surface layer had an average thickness of 1.0 mm to 1.5 mm.
A semi-rigid urethane foam molded product having the same homogeneous cell structure as in Example 2 was obtained.

The properties of the obtained urethane foam molded product having a high density layer in the surface layer were as shown in Table 8 below.

(Comparative example) As a comparative example, low boiling point blowing agents CFC-11 and CFC-1
Dabco33LV, U-100, PolyC, which has been used in the prior art as a catalyst without using 13 etc.
AT9 (manufactured by Air Products, sold by Sun-Apro Co., Ltd.)
The mold temperature was set to 55° C. (Comparative Examples 3 and 4). Comparative Examples 3 and 4 are shown in Table 7(a) and Table 7(b) below, respectively, by comparing the formulation of this Comparative Example with the above Example 3.

Further, the characteristics of Comparative Example 3 and Comparative Example 4 are shown in Table 8 below in comparison with the characteristics of Example 3.

[Margins below] As is clear from Table 8 above, it was not possible to form a high-density surface layer with the conventionally used catalysts.

The reactivity of the mixed solution used for injection is shown in the table below.
9.

For reference, in (1), (2), and (3) of Example 3, when the overpack ratio was made extremely low and the resin liquid was injected to the extent that it could barely be filled into the mold, the result was that Also, the foaming of the surface layer was not sufficiently suppressed, and a high-density surface layer with a uniform thickness was not formed, resulting in a molded product with a foamed surface layer and a normal thin film skin. However, the difference from normal molded products is that when the cross section of the product is cut in the thickness direction, a line-like boundary exists between the surface layer and the intermediate foam layer.Low-density surface layer - Line boundary - Low-density intermediate foam It was layered.

(Example 4) Next, as a catalyst, 1,2-dimethylimidazole and U
- An example is shown using CAT SA1 and a resin in a water-absorbed state as a blowing agent.

In this example, the catalyst and water-absorbed resin are shown in Table 10.
Each liquid was added as shown in , and prepared by dividing it into three components, first, second, and third, and molded products were created under the same conditions and operating procedures as in Example 1. When this molded product was cut in the thickness direction and the cross-sectional shape was confirmed, it was found to be a homogeneous semi-hard material with a high-density surface layer having an average thickness of 1.0 to 1.2 mm, similar to Example 1. A urethane foam molded product was obtained.

The properties of the obtained urethane foam molded product having a high density layer in the surface layer were as shown in Table 11 below.

The reactivity of the liquid mixture used for injection was as shown in Table 12 below.

[Margin below] As is clear from Table 12 above, when a water-absorbing resin is used, the reaction delay can be increased.

(Example 5) Next, an example of a rigid urethane foam molded product having a high-density surface layer will be shown.

In this example, the polyols used are pentaerythol-based polyether polyol (PE-
450, OHV=450mεK-OH/g) and 90g of ethylenediamine-based polyether polyol (Takeda Pharmaceutical (
Actol GR-07 manufactured by Co., Ltd., OHV=760mεK
-OH/g) 10g, silicone foam stabilizer (
1.0 g of F-305 (manufactured by Shin-Etsu Chemical Co., Ltd.), 1.0 g of distilled water as a blowing agent, 0.6 g of 1,2-dimethylimidazole and 0.6 g of U-CAT SA1 as catalysts were added, and the mixture was heated to 20°C. A temperature-controlled mixed solution was prepared. MDI-CR200, which was temperature-controlled at 20°C, was added to this as isocyanates.
134g of the mixture was added, immediately stirred for 8 seconds with a homomixer, and immediately poured into an aluminum mold whose temperature was controlled at 20°C and 30°C similar to that used in Example 1. The upper lid was closed and pressed with a clamp. After leaving it for 10 minutes (for curing) to withstand the foaming pressure, the upper lid was opened and the molded product was taken out. When this molded product was cut in the thickness direction and the cross section was examined, it was found that a high-density surface layer with an average thickness of 1 mm was formed in good condition, and it was a rigid urethane foam molded product having a homogeneous cell structure.

The resulting rigid urethane foam molded product having a high-density surface layer was as shown in Table 13 below.

The reactivity of the mixed solution used for injection was as shown in Table 14 below.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the foaming degree and gelation degree and the elapsed time on the mold contact surface and non-contact surface for forming a high-density surface layer in a closed mold.

Claims (4)

[Claims] Claim 1: A urethane foam molded product in which a resin liquid containing isocyanates, polyols, catalysts, blowing agents, auxiliary agents, etc. is injected into a mold in one shot to form a high-density surface layer on the surface. In the method for producing, the catalyst is (1) a morpholine compound, (2) a piperazine compound, (3) an imidazole compound, (4) a triazine compound, (5) an amidine compound or an organic acid of an amidine compound. Using at least one selected from salt,
Or, by using a catalyst consisting of any combination of groups (1), (2), (3), (4), and (5), there is a difference in gas generation due to a difference in chemical reaction between the isocyanate and the blowing agent. That is, it is a method for producing a urethane foam molded product in which a high-density surface layer is formed on the surface based on the difference in gasification reaction. Morpholine, N-
At least one selected from methylmorpholine and N-ethylmorpholine; (2) piperazine compounds include methylhydroxypiperazine, trimethylaminoethylpiperazine, and bis[2-(4-methylpiperazinyl);
(3) At least one selected from the group consisting of 1-methyl-4'-(dimethylaminoethyl)piperazine, 1-methyl-4'-(dimethylaminoethyl)piperazine; -methyl-imidazole), 1,1'-(oxydiethylene)bis(imidazole) and/or 1-position-substituted imidazole compounds, i.e. 1-methylimidazole, 1
-ethylimitazole, 1-propylimidazole, 1
-butylimidazole, 1,2-dimethylimidazole, 1-ethyl-2-methylimidazole, and/or other imidazole compounds selected from 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-ethylimidazole; At least one (4) triazine compound is N,N',N''-tris(dimethylaminopropyl)hexahydro-S-triazine, N,
N',N''-Tris(dimethylaminopropyl)hexahydro-S-triazine organic acid salt, N,N',N''
-Tris(dimethylaminopropyl)hexahydro-
at least one selected from S-triazine and a mixture of N,N',N''-tris(dimethylaminopropyl)hexahydro-S-triazine with an organic acid salt; (5) the amidine compound is 1,8- Diazabicyclo (5
,4,0) at least one selected from organic acid salts of undecene-7 or 1,8-diazabicyclo(5,4,0)undecene-7, (6) the above (1), (2), ( 3),
(4), a mixture consisting of any combination of groups (5),
A method for producing a urethane foam molded article, characterized in that a high-density surface layer is formed on the surface based on the difference in gas generation due to the difference in chemical reaction between the isocyanate and the blowing agent, that is, the difference in gasification reaction. . 2. The method of manufacturing a urethane foam molded product according to claim 1, wherein the temperature of the mold is set in a range of 15°C to 40°C, and the temperature of the resin liquid is set in a range of 15°C to 30°C. 3. The method for producing a urethane foam molded article according to claim 1, wherein the blowing agent is water. 4. The method for producing a urethane foam molded article according to claim 1, wherein the blowing agent is in the form of a water-absorbed resin.