JPS6274917A - Manufacturing method of rigid polyurethane foam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing rigid polyurethane foam, particularly void and shear 2/long rigid polyurethane foam produced by casting foaming.

(Prior art) Rigid polyurethane foam has excellent insulation properties, and is used not only to keep homes and warehouses warm and cold, but also as the core material of sandwich panels and outer boxes of electric refrigerators. In addition, it is used in various fields as a casing material for furniture and equipment with a textured pattern on its outer surface.

When manufacturing rigid polyurethane foam, a method is generally used in which a stock solution is injected into the cavity of a female mold or a target object, and then foamed and cured. Recently, these construction targets have become larger, and the voids have become increasingly complex in shape with many obstacles such as piping. In addition, complex and elaborate uneven patterns on the outer surfaces of furniture, casings, etc. are now required. Furthermore, the demand for products with high surface smoothness has become extremely high.

In addition to the increasing size and complexity of the injection target, there is also a need to shorten the rotation time of the mold and increase work efficiency.As a result, the foaming and curing speed of the polyurethane stock solution has been accelerated, while the injection equipment has also been changed from the conventional one. The low-pressure method used in the invention has been switched to a high-pressure injection foaming machine, and it has become possible to quickly inject large amounts of stock solution.(Problem that the invention seeks to solve) When curing is carried out rapidly, a method is generally used in which crude diphenylmethane diisocyanate and a polyol are reacted in the presence of a catalyst in a one-shot method.

At this time, the stock solution in the middle of foaming causes air to be drawn in, cells to meet,
Alternatively, gas retention occurs due to cell collapse, resulting in voids.

The stock solution in the middle of foaming causes an abnormal flow at the tip of its expansion due to friction with the wall surface of the cavity, and the bubbles become coarse and form a so-called shear line. The presence of such voids or shear lines poses a serious problem because they significantly reduce the properties and commercial value of rigid polyurethane foams.

(Means for Solving the Problem) As a result of various studies to eliminate voids and shear lines, the inventors of the present invention found that 4.2'
- 5 to 50% by weight of diphenylmethane diisocyanate
The present invention was achieved by discovering that it is effective to use the crude diphenylmethane diincyanate contained therein.

△ That is, the present invention is as follows.

In a method for producing a rigid polyurethane foam by reacting a polyisocyanate, a polyol, a catalyst, a foam stabilizer, and other additives as necessary, 4,2'-diphenylmethane diisocyanate is used as a polyinsyanate in 5 to
Rigid polyurethane foam O characterized by using crude diphenylmethane diincyanate containing 50% by weight
Manufacturing method.

The crude diphenylmethane diisocyanate used to produce the rigid foam is usually 35 to 65% by weight of 4.4'-diphenylmethane diisocyanate, 0 to 5% by weight of 4.2'-diphenylmethane diisocyanate, and a methylene-crosslinked polyphenyl polyester having a functional group number of 3 or more. It consists of 65 to 35% by weight of isocyanate (hereinafter abbreviated as polynuclear substance).

The crude diphenylmethane diisocyanate in the present invention is 4,2'-diphenylmethane diisonoanate 5-
A polyisocyanate consisting of 50% by weight, 60 to 30% by weight of 4.4-diphenylmethane diisocyanate, and 65 to 35% by weight of polynuclear bodies is used. Particularly suitable 4.
The content of 2'-diphenylmethane diisocyanate is 1
0 to 30 weight 2.

In injection foaming of polyurethane, in order to prevent the raw solution from entering every corner of the void and voids from occurring, it is necessary to suppress the increase in viscosity as much as possible until the final stage of foaming1. It is necessary to suppress the increase in viscosity in order to reduce the friction with the stock solution and narrow the range of shear line formation. Furthermore, in order to perform foaming uniformly, it is necessary to increase the compatibility between the crude diphenylmethane diincyanate and the polyol.

When 4.2'-diphenylmethane diisocyanate is added and mixed with crude diphenylmethane diisocyanate, it is possible to suppress the increase in the viscosity of the stock solution during foaming and to increase the compatibility between the crude diphenylmethane diisocyanate and the polyol. -Diphenylmethane diisocyanate has an excellent effect, but no effect is observed if the content in the polyisocyanate is less than 5% by weight, and if it exceeds 50% by weight, it becomes difficult to control the foaming conditions. Examples of polyols include ethylene glycol, fluoropylene gelylcol, diethylene glycol,
Triethylene glycol, cyfropyrene glycol, glycerin, trimethylolpropane, 1,3,6-hexandriol, pentaerythritol, sorbitol, sucrose, bisphenol A1 novolac, hydroxyl 1,2-polybutadiene, hydroxylated 1
．． Hydroxyl number 200-800 obtained by addition polymerizing alkylene oxide to polyhydric alcohols such as 4-polybutadiene and/or these polyhydroxy compounds
mfKOH/SF polyether polyol. Also, compounds containing two or more active hydrogens such as alkanolamines such as jetanolamine and triethanolamine, ethylenediamine, diethylenetriamine, ammonia, aniline, tolylenediamine, quinolylenediamine, and diaminodiphenylmethane, and/or these amines. Classes include ethylene oxide, propylene oxide,
Hydroxyl value 200-800mfKOH/ obtained by addition polymerization of butylene oxide, styrene oxide, etc.
Polyether polyols and polytetramethylene ether glycols of f can also be used.

In addition to the above, high-grade fatty acid ester polyols, polyester polyols obtained by reacting polycarboxylic acids with low molecular weight polyols, polyester polyols obtained by polymerizing caprolactone, high-grade polymers containing OH groups such as castor oil, dehydrated castor oil, etc. Fatty acid esters can also be used.

Catalysts useful for the present invention include, for example, N;

N', N'-tetramethyl-hexamethylenediamine, pentamethyldiethylenetriamine (PMDETA)
, dimethylpalmitylamine, trimethylaminoethylpiperazine, triethylamine, triethylenediamine, N, N, N/, N/-tetramethyl pronodiamine, N, N, N', N'-tetramethyl hexamethylene diamine ( TMHD), N, N,
N', N'-tetramethyl-1,3-butanediamine, N,N-dimethylφcyclohexylamine, bis(
2-dimethylaminoethyl)ether, N, N-N'
-) Lis(dimethylaminoethyl)hexahydrotriazine, N, N7 N'-<diethylaminepropyl)
Hexahydrotriazine, 2,4-bis(dimethylaminomethyl)phenol, 2,4. G-) Lis(diethylaminemethyl)phenol, amines such as tetramethyl guanidine, tin octoate, tin oleate, diptyltin dilaurate, lead naphthenate, cobalt 2-ethylhexanoate, potassium acetate, sodium propionate, Organometallic compounds such as potassium octoate.

In the present invention, a foaming agent and a foam stabilizer are used to form a foam. Examples of the foaming agent include water, trichloromonofluoromethane,
Dichlorodifluoromethane, methylene chloride, trichlorotrifluoroethane, dibromotetrafluoroethane, trichloroethane.

One or more types of pentane, hexane, etc. are used.

The foam stabilizer in the present invention is a conventionally known organosilicon surfactant, such as L-501 manufactured by Nippon Unicar Co., Ltd.
L-520, L-532, L-540, L-544, L
-3550, L-5302, L-5305, L-532
0, L-5340, L-5350, L-5410, L-
5420, L-5421, L-5710, L-5720
5R-190°SH-192, SH-193, 5I (-194, SH-
195, 5H-200, 5RX-253, etc., and F-114, F-121, F-12 manufactured by Shin-Etsu Silicone Co., Ltd.
2, F-220% F-230, F-258, F-260
B%F-305, F-306, F-317, F-341
, F-601, F-606, X-20-200, X-2
0-201, etc., and TFA manufactured by Toshiba Silicone Co., Ltd.
-4200, TFA-4202, etc.

In addition, as a flame retardant, for example, tris(2-chloroethyl)
Phosphate, tris (dichloroglovir) phosphate, tris (dibromopropyl) phosphate, CR-505 and CR-507 manufactured by Inuhe Kagaku Co., Ltd., Phoogard 2XC-20 and C-22-R manufactured by Monsando Chemical Co., Ltd.
, Fyro16 manufactured by Stoffer Chemical Co., Ltd., etc. can be used.

Plasticizers, fillers, stabilizers, colorants, etc. can be added as necessary.

To carry out the present invention, a polyurethane foaming machine is used to mix predetermined amounts of polyol, catalyst, blowing agent, foam stabilizer, flame retardant, and other auxiliary agents to form a resin liquid. Polyisocyanate is continuously and rapidly mixed at a constant ratio. The resulting rigid polyurethane foam stock solution is injected into the cavity or mold. At this time, the flow rate ratio of the resin liquid and the polyisocyanate is adjusted so that the equivalent ratio of the organic polyisocyanate and the active hydrogen-containing compound is 0.8 to 3.0. After injection, the rigid polyurethane foam will expand and harden within a few minutes.

(Example) The present invention will be specifically described below with reference to Examples.

The raw materials used in the examples are as follows.

In addition, parts indicate parts by weight. Polyether A: Hydroxyl value 400 mfKOH obtained by addition polymerizing propylene oxide to sucrose.
/S' polyol.

・Polyether B: Obtained by addition polymerization of propylene oxide to tolylene diamine.
00 mfKOH/r polyol.

・Polyincyanate C: 4.2'-diphenylmethane diisocyanate 3% by weight, 4.4'-diphenylmethane diisocyanate 43.4% by weight, polynuclear body 53.6
NCO group concentration 30.8% by weight, viscosity 170
Crude diphenylmethane diisocyanate at cps/25°C.

・Polyisocyanate) D: 4.2'-diphenylmethane diisocyanate 10% by weight, 4.4'-diphenylmethane diisocyanate 47.1% by weight, polynuclear body 4
Crude diphenylmethane diisocyanate with an NCO group concentration of 31.3 wt.%, containing 2.9 wt.%, and a viscosity of 81 cps/25°C.

・Polyisocyanate E: 4.2'-diphenylmethane diisocyanate 20% by weight 414'-diphenylmethane diisocyanate 47.8% by weight, polynuclear body 33
・NCO group concentration 31.9% by weight, including 2% by weight, viscosity 4
4 CpS/25°C crude diphenylmethane diisocyanate Foam stabilizer: L-5421 Catalyst: TMHD and PMDETA Foaming agent;
Trichloromonofluoromethane (F-11) Example 1 60 parts of polyol A and 40 parts of polyol B were uniformly mixed.

100 parts of this polyol mixture was added to
, D and 100 parts of each were mixed, and the time required for the mixture to become transparent was measured, and the results were as shown in Table 1.

(hereinafter referred to as Ni) Table 1 That is, 4.2 in crude diphenylmethane diisocyanate
It is clear that as the content of '-diphenylmethane diisocyanate increases, its compatibility with the polyol increases, and thus the clearing time as the reaction progresses is shortened.

Example 2 A resin solution having the composition shown in Table 2 was prepared, and this was rapidly mixed with polyincyanee) C, D, or E, respectively, and immediately poured into a vertical test aluminum panel with dimensions of 400 x 400 x 5 (1 mm).

The amount of injection was adjusted so that 10 to 20% of the filler was left unfinished at the top after foaming was completed.

After heating the panel to 60°C for 10 minutes, remove the hardened rigid foam. The expanded height of the rigid foam was taken as 100%, and the ratio between the height of the generated shear line and the height of the foam was measured.

In addition, the state of occurrence of voids was observed.

As is clear from Table 2 (as the content of 4,2'-diphenylmethane diisocyanate increases, the position of the shear line moves upwards. Therefore, when the shear line is completely filled, the adjacent shear line collides with the wall surface and becomes more likely to collapse and disappear. .The occurrence of voids is also reduced.

<,'-: ,:,-,,+ Table 2 (Note) Acceptable, ○Good, ◎Excellent Example 3 Using a high-pressure foaming machine, the flow rate ratio of resin liquid and polyisocyanate was as shown in Table 2. The mixture was adjusted to match and injected into the outer box of a large refrigerator. After leaving it for a few days, the outer box was disassembled and investigated. As a result, voids and shear lines were observed in some parts of the formulation of Table 2, Ku 1, but these were not observed in the formulations of Kaku 2 and N13.

(Effects of the invention) - By carrying out the present invention, the viscosity increase rate is slower than the foaming rate of the raw solution, and the compatibility between polyisocyanate and polyol is increased, so that voids and shear lines are formed in rigid polyurethane foam. It is possible to obtain a homogeneous form without any occurrence of

Claims (1)

[Claims] In a method for producing a rigid polyurethane foam by reacting a polyisocyanate, a polyol, a catalyst, a foam stabilizer, and other additives as necessary, 4,2'-diphenylmethane diisocyanate is used as the polyisocyanate for 5 to 50 minutes.
A method for producing a rigid polyurethane foam, characterized by using crude diphenylmethane diisocyanate containing 50% by weight.