JP6218306B2 - Polyurethane foam - Google Patents

Description

  The present invention relates to a polyurethane foam that can be manufactured without generating scorch inside a block in slabstock molding, and in particular, has low hardness, sufficient hardness, bending resistance (shape followability), shape memory property, Relates to a semi-rigid polyurethane foam having

While having high hardness, the one with the intermediate characteristics of “rigid polyurethane foam” and “soft polyurethane foam” having a certain degree of flexibility is also called “semi-rigid polyurethane foam”, and high hardness is required. It is suitably used as a member such as an automobile ceiling base material in which thermoforming (press molding) is essential.
Various semi-rigid polyurethane foams have been developed so far. For example, the polyurethane foam described in Patent Document 1 has a density that is too high and is not preferable in terms of weight reduction.

As a method for reducing the density of polyurethane foam, there is a method of increasing the amount of water added as a foaming agent, but water reacts with an isocyanate compound, so the amount of heat generated by the reaction increases, and the resulting foam has scorch. Likely to happen.
This phenomenon is particularly noticeable in the case of slabstock molding that produces large block polyurethane foams, and in the worst case there is even a fire hazard.

Thus, in order to mold a low-density polyurethane foam, suppression of scorch generation in the foam becomes a problem. Therefore, in Patent Document 2, by adding excess water, internal heat generated during foam formation can be reduced. It has been proposed to reduce the heat by removing excess water.
However, in Patent Document 2, only a low density is achieved by adding a large amount of water, and since it is inferior in flexibility (elongation), it must follow a curved surface such as the ceiling of an automobile. In the case of using for the above, there is a problem that cracks occur at the bent portion. In general, a base material for an automobile ceiling is formed by press-molding a semi-rigid polyurethane foam bonded with a skin material.

On the other hand, the present inventor has previously proposed a polyurethane foam having both low density and high hardness without generating scorch (Patent Document 3).
However, in the previously proposed polyurethane foam, there was a point to be improved that cracking may actually occur depending on the thickness of the foam and the shape of the bent surface when press-molding it on a bent surface such as an automobile ceiling. . As described above, the conventional semi-rigid polyurethane foam tends to be inferior in shape followability as the density and hardness are lowered.

Japanese Patent No. 3367091 Patent No. 4079254 JP 2012-46589 A

  The present invention is a polyurethane foam that can be produced without generating scorch inside the block, and has a low hardness and a high hardness, and is excellent in shape followability (bending resistance) and shape memory. It is an object to provide a rigid polyurethane foam.

In order to solve the above problems, the present inventor has conducted extensive studies,
By using at least four kinds of polytetramethylene ether glycol and derivatives thereof, polyether polyol, polyester polyol, polyhydric alcohol, and having an average hydroxyl value adjusted to a specific value as a polyol compound,
Although it is low density and high hardness, when it is processed into a plate shape, it can be bent at room temperature (about 25 ° C) at 90 ° or more, and even when it is bent 180 ° at room temperature, it cracks (cracks and cracks) Semi-rigid, with a shape memory property that it is difficult to enter, and its elongation characteristics (elongation and bending resistance) improve as the temperature rises, and when it is returned to room temperature again, it can retain its bent shape at high temperatures. It was found that a polyurethane foam was obtained.

That is, the polyurethane foam of the present invention is a polyurethane foam obtained by reacting a polyol component containing a polyol compound, a foaming agent, a foam stabilizer, and a catalyst with an isocyanate component,
The polyol compound has (i) a polytetramethylene ether glycol and / or a derivative thereof having a number average molecular weight of 1000 to 3000 and a hydroxyl value of 37 to 112 mgKOH / g, and (ii) a number average molecular weight of 300 to 1000 and a hydroxyl value of At least 4 of a polyether polyol of 156 to 560 mg KOH / g, (iii) a polyester polyol having a number average molecular weight of 500 to 1300 and a phthalic acid having a hydroxyl value of 100 to 200 mg KOH / g as an initiator, and (iv) a polyhydric alcohol. Including seeds, having an average hydroxyl value of 190 to 300 mg KOH / g, and
The isocyanate component is crude MDI having an NCO content of 28-33%.
It is characterized by being.
At this time, with respect to 100 parts by weight of the polyol compound, the (i) polytetramethylene ether glycol and / or a derivative thereof is 10 to 20 parts by weight, the (ii) the polyether polyol is 40 to 50 parts by weight, and the (iii) It is preferable that the polyester polyol is 25 to 35 parts by weight and the (iv) polyhydric alcohol is 5 to 15 parts by weight.

The polyurethane foam of the present invention can be produced without generating scorch inside the block even in slab stock molding, and has low hardness, high hardness, and excellent flexibility and shape followability (bending resistance). Since it is a thing, it can be preferably used as a base material for interiors such as a ceiling of automobiles, door trims, instrument panels, and the like and because of its shape memory property, it requires thermoforming.
In particular, the polyurethane foam of the present invention has a density of 25 to 35 kg / m ³ and a C hardness (hardness measured with an Asker rubber hardness meter C type) of 30 or more, which has not existed at room temperature. Excellent bending resistance that the foam does not crack even when it is bent 180 °.

In addition, the polyurethane foam of the present invention has improved elongation characteristics (elongation and bending resistance) as the temperature rises, and has very good shape following at high temperatures. Furthermore, it has an excellent shape memory property that a shape expressed by bending at a high temperature can be held when returned to room temperature.
It should be noted that the polyurethane foam of the present invention has low density and excellent properties such as hardness and bending resistance, regardless of whether it is produced by molding or sprayed on site. is there.

The polyurethane foam of the present invention is obtained by reacting a polyol component containing a polyol compound, a foaming agent, a foam stabilizer, and a catalyst with an isocyanate component,
The polyol compound includes (i) polytetramethylene ether glycol and / or a derivative thereof, (ii) polyether polyol, (iii) polyester polyol, and (iv) polyhydric alcohol, and has an average hydroxyl value of 190 to The one prepared to 300 mg KOH / g is used.
If the average hydroxyl value of this polyol compound is too low, the hardness of the resulting foam may be insufficient. If it is too high, scorch may be generated inside the block, or measured according to JIS K6400-5. The elongation is less than 12% and sufficient bending resistance is difficult to obtain, preferably 210 to 280 mgKOH / g. The average hydroxyl value can be prepared by appropriately selecting the hydroxyl value and blending ratio of each polyol.

The four kinds of blends in 100 parts by weight of a polyol compound are (i) 10 to 20 parts by weight of polytetramethylene ether glycol and / or a derivative thereof, (ii) 40 to 50 parts by weight of polyether polyol, (iii) ) polyester polyol 25 to 35 parts by weight, shall be the (iv) a polyhydric alcohol is from 5 to 15 parts by weight.

As the polyol compound (i) polytetramethylene ether glycol and / or derivative thereof, those having a number average molecular weight of 1000 to 3000 and a hydroxyl value of 37 to 112 mgKOH / g are used.
Polytetramethylene ether glycol having a number average molecular weight of less than 1000 and / or its derivative tends to shrink the foam at room temperature, so that it lacks dimensional stability and exceeds 3000 polytetramethylene ether glycol and / or In the derivative, the desired hardness cannot be expressed.
If the hydroxyl value is less than 37 mgKOH / g, the hardness of the resulting foam will be low, and if it exceeds 112 mgKOH / g, the foam tends to shrink at room temperature, resulting in lack of dimensional stability.
Thus, by blending (i) polytetramethylene ether glycol having a number average molecular weight of 1000 to 3000 and a hydroxyl value of 37 to 112 mgKOH / g and / or a derivative thereof, flexibility is improved and shape followability (resistance to resistance) A semi-rigid polyurethane foam having excellent bendability and shape memory is obtained.

(I) the proportion of polytetramethylene ether glycol and / or derivatives thereof, in the polyol compound based on 100 parts by weight of Ru is 10 to 20 parts by weight. If it is less than 10 parts by weight, it is difficult to obtain desired elongation and shape followability (bending resistance), and if it exceeds 20 parts by weight, the hardness tends to be insufficient.
As specific examples of (i), trade names “PTMG1000”, “PTMG1500”, “PTMG2000”, “PTMG3000” manufactured by Mitsubishi Chemical Corporation; trade names “PTG-L1000”, “PTG-L2000” manufactured by Hodogaya Chemical Co., Ltd. “PTG-L3000” and the like can be mentioned. Among them, a copolymer of tetrahydrofuran and neopentyl glycol is preferable, and one of these may be selected, or two or more may be used in combination.

As the polyol compound (ii) polyether polyol, those having a number average molecular weight of 300 to 1000 and a hydroxyl value of 156 to 560 mgKOH / g are used. The average functional group number should just be the range of 2-4, and a preferable average functional group number is 3.
In polyether polyols having a number average molecular weight of less than 300, the foam shrinks at room temperature or cell roughness cannot be suppressed. Therefore, the dimensional stability is lacking. Since it becomes impossible to express, it is preferably 400 to 800.
If the hydroxyl value is less than 156 mgKOH / g, the desired hardness cannot be achieved, and if it exceeds 560 mgKOH / g, the foam tends to shrink at room temperature.
As described above, (ii) by adding a polyether polyol having a number average molecular weight of 300 to 1000 and a hydroxyl value of 156 to 560 mgKOH / g, it is possible to improve hardness and rigidity.

The mixing ratio of (ii) a polyether polyol, a polyol compound in 100 parts by weight, Ru is 40 to 50 parts by weight. If it is less than 40 parts by weight, it is difficult to obtain desired hardness and rigidity, and if it exceeds 50 parts by weight, the foam may shrink.
Specific examples of (ii) include “Actol T-300”, “Actol T-400”, “Actol T-700”, “Actol T-1000”, etc., manufactured by Mitsui Chemicals. One of these may be selected, or two or more may be used in combination.

As a polyester polyol having a polyol compound (iii) phthalic acid (including terephthalic acid) as an initiator, those having a number average molecular weight of 500 to 1300 and a hydroxyl value of 100 to 200 mgKOH / g are used.
Polyester polyols having a number average molecular weight of less than 500 tend to shrink the foam at room temperature, so that the dimensional stability is lost. If the number average molecular weight exceeds 1,300, the desired hardness cannot be expressed. 1120.
When the hydroxyl value is less than 100 mgKOH / g, the desired hardness cannot be exhibited, and when it exceeds 200 mgKOH / g, the foam becomes brittle and the shape followability is lost.
Thus, (iii) by blending a polyester polyol having a number average molecular weight of 500 to 1300 and a hydroxyl value of 100 to 200 mg KOH / g as an initiator, phthalic acid can be made finer, and hardness and elongation can be improved. Improvement is possible. Incidentally, polyester polyols that use a carboxylic acid other than phthalic acid (for example, adipic acid, succinic acid, etc.) as an initiator have problems that the desired hardness cannot be exhibited and cell roughness cannot be suppressed.

The mixing ratio of (iii) a polyester polyol, polyol compounds in 100 parts by weight, Ru is 25 to 35 parts by weight. If it is less than 25 parts by weight, there is a risk that foam cell roughening or shrinkage will occur. If it exceeds 35 parts by weight, the viscosity of the entire polyol compound after mixing will increase and poor stirring will occur, so a good polyurethane foam can be obtained. It's hard to be done.
Specific examples of (iii) include trade names “Maximol RLK-035” and “Maximol RLK-085” manufactured by Kawasaki Kasei Kogyo Co., Ltd. Among them, polyester polyols using terephthalic acid as an initiator are preferable. Yes, one of these may be selected, or two or more may be used in combination.

The polyol compound (iv) polyhydric alcohol is not particularly limited as long as it is a dihydric or higher alcohol. For example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, diglycerin, trimethylolpropane, pentaerythritol. From these, one type may be selected, or two or more types may be used in combination. The number of functional groups is preferably in the range of 2 to 4, and the molecular weight is preferably about 50 to 200.
Such (iv) polyhydric alcohol acts as a crosslinking agent and realizes high hardness of the polyurethane foam in the present invention.
(Iv) For the mixing ratio of the polyhydric alcohol, a polyol compound in 100 parts by weight, Ru is 5 to 15 parts by weight. If it is less than 5 parts by weight, the action as a crosslinking agent becomes insufficient, the cell becomes rough or sufficient hardness and strength cannot be obtained, and if it exceeds 15 parts by weight, the foam tends to shrink and dimensional stability Become scarce.

  In addition, as the polyol compound in the present invention, in addition to the above (i) to (iv), it is possible to add a polyol and a crosslinking agent that are usually used in the production of urethane foam within a range not impairing the effects of the present invention. it can.

In the polyol component, as the blowing agent, at least one of water, methylene chloride, pentane, cyclopentane, hexane, cyclohexane, carbon dioxide gas, etc. is used, and in particular, water and methylene are used to alleviate the heat generated by the reaction. Use with chloride is desirable. As the “water” in the present application, for example, ion exchange water, tap water, distilled water, or the like may be used.
When water is used as the foaming agent, the amount is preferably 2.5 to 4.5 parts by weight with respect to 100 parts by weight of the polyol compound. If it exceeds 4.5 parts by weight, the amount of heat generated by the reaction with the isocyanate component increases, and scorch is generated inside the slab stock foam. If it is less than 2.5 parts by weight, the resulting foam has a high density (greater than 35 kg / m ³ ), which is not preferable from the viewpoint of cost and weight reduction.
Further, the foaming agent other than water has an effect of relaxing the reaction heat accumulated in the slab stock foam by the heat of vaporization, and the effect can be expected as the addition amount increases. 5 to 15 parts by weight is preferable with respect to parts. If it exceeds 15 parts by weight, the resulting urethane foam is softened and the cells become rough. When the amount is less than 5 parts by weight, the vaporization heat cooling effect is lowered, and scorch is likely to be generated inside the slab stock foam.

What is necessary is just to use what is generally marketed as an organosilicone type surfactant as a foam stabilizer in a polyol component.
Specifically, product names “SZ-1919”, “SH-190”, “SH-192”, “SH-193”, “SH-194”, “SF-2904”, “Toray Dow Corning” Product name “B4900”, “B8002”, “B8110”, “B8123”, “B8228”, “B8232”, “BF2370”, “BF2470”; manufactured by Momentive Performance Materials Product names “L-568”, “L-580”, “L-590”, “L-598”, “L-626”, “L-635”, “L-638”, “L-650”, “SC-155”: Shin-Etsu Silicone's product names “F-114”, “F-121”, “F-258”, etc. May be.
As for such a foam stabilizer, 1-5 weight part is preferable with respect to 100 weight part of polyol compounds. If it is less than 1 part by weight, sufficient foam regulating effect cannot be obtained, and cell roughening tends to occur in the foam. If it exceeds 5 parts by weight, the foam tends to shrink and the dimensional stability is poor.

In the polyol component, the catalyst is for accelerating the urethanization reaction between the polyol compound and the isocyanate component described later. The catalyst may be about 0.1 to 3 parts by weight with respect to 100 parts by weight of the polyol compound.
The catalyst may be any known one in foaming of urethane foam, and is not particularly limited, but a tertiary amine catalyst is suitable. Tertiary amine catalysts include triethylenediamine, triethylamine, tripropylamine, triisopropanolamine, tributylamine, trioctylamine, N-methylmorpholine, N-ethylmorpholine, bis (2-dimethylaminoethyl) ether, and the like. 1 type may be selected from these, and 2 or more types may be used together.
In the present invention, only the tertiary amine catalyst may be used as the catalyst, or a catalyst other than the tertiary amine catalyst may be used in combination depending on the application.

By using crude diphenylmethane diisocyanate (crude MDI) having an NCO content of 28 to 33% as the isocyanate component, it becomes possible to produce a slabstock foam with high hardness without generating scorch inside the block. . At this time, two or more types of MDI having different molecular weights or NCO contents may be mixed and adjusted to the NCO content range.
With a crude MDI having an NCO content of less than 28%, the desired hardness cannot be obtained. With a crude MDI of more than 33%, the amount of heat generated by the reaction with the polyol compound increases, and scorch tends to be generated in the urethane foam. By the way, when using pure MDI, if mixed with crude MDI so as to be within the range of the NCO content, the crosslink density when pure MDI is used alone becomes high and hard and cannot be bent. Trouble can be solved.
In addition, with TDI (tolylene diisocyanate), its NCO content is very high at 48.3%, the reactivity is too high to prevent the occurrence of scorch, and cell roughness or hardness There is also a problem that it drops.

  If the isocyanate index is too low, the desired hardness cannot be expressed. If the isocyanate index is too high, the amount of heat generated by the reaction with the polyol compound increases and scorch is easily generated in the urethane foam. Preferably, it is 110-140.

  As described above, the present invention provides a specific polytetramethylene ether glycol and / or a derivative thereof, a specific polyether polyol, a specific polyester polyol, and a polyhydric alcohol, as described above, from among a myriad of polyols. By using a polyol compound having an average hydroxyl value after mixing of 190 to 300 mgKOH / g, the foam can be bent at 180 ° at room temperature while having low density and high hardness. It is possible to obtain a semi-rigid polyurethane foam which is not easily cracked (cracked or cracked) and has excellent shape followability.

  In addition to the polyol compound, the foam stabilizer, the foam stabilizer, the polyol component containing the catalyst, and the isocyanate component, the raw materials for the polyurethane foam as described above include a compatibilizer, a flame retardant, a viscosity reducer, Additives commonly used in the production of polyurethane foams, such as fillers, colorants, stabilizers, antioxidants, and UV absorbers, may be used.

  When producing the polyurethane foam of the present invention, the one-shot method in which the polyol component containing the polyol compound, the foaming agent, the foam stabilizer, and the catalyst as described above and the isocyanate component are directly reacted, or the polyol component. Any of the prepolymer methods can be employed in which a prepolymer having an isocyanate group at the terminal is obtained by reacting with the isocyanate component in advance and a polyol component is reacted therewith.

In the polyurethane foam of the present invention, the exothermic temperature at the time of foam formation can be about 170 ° C. or less.
Conventionally, in order to produce a low density and high hardness polyurethane foam, it was necessary to increase the amount of water as a foaming agent and set the hydroxyl value of the polyol high, so when producing with the slabstock method, As a result, the scorch due to heat storage is likely to occur inside the block, and as a result, there is a concern about the risk of fire, making it extremely difficult to manufacture. Since the temperature is as low as about 170 ° C. or less, the risk of fire can be reduced, the slab stock method such as continuous slab foaming can be safely performed, and the occurrence of scorch and the like inside the block can be effectively prevented.

The polyurethane foam of the present invention preferably has a density measured according to JIS K7222 of 25 to 35 kg / m ³ and a C hardness of 30 to 40. When the C hardness is less than 30, it is difficult to use for applications such as automobile ceiling base materials where rigidity and hardness are important, and when it exceeds 40, bending resistance and shape followability are poor.
Further, in the polyurethane foam of the present invention, the bendable angle at room temperature is 90 ° or more when processed into a plate shape, and cracks (cracks and cracks) hardly occur even when it is bent 180 ° at room temperature. In the case of a conventional semi-rigid urethane foam, if the same test is performed, it can be bent only at about 60 ° or cracks at about 120 °, so the polyurethane foam of the present invention is very excellent in bending resistance. I understand.
Furthermore, in the polyurethane foam of the present invention, the elongation measured in accordance with JIS K6400-5 has a correlation with the temperature, and the elongation is improved as the temperature rises. Have. Moreover, when it returns to room temperature, there exists a characteristic (shape memory property) which can hold | maintain the shape expressed by bending at high temperature.

Examples 1-13, Comparative Examples 1-10
≪Raw materials used≫
○ Polyol compound (1) Polytetramethylene ether glycol (PTMG) or its derivative-PTMG having a number average molecular weight of 1800 and a hydroxyl value of 62 mgKOH / g (trade name “PTMG2000” manufactured by Mitsubishi Chemical Corporation)
-PTMG derivative having a number average molecular weight of 2000 and a hydroxyl value of 56 mgKOH / g (trade name “PTG-L2000” manufactured by Hodogaya Chemical Co., Ltd.)
-PTMG with a number average molecular weight of 3000 and a hydroxyl value of 37 mgKOH / g (trade name “PTMG3000” manufactured by Mitsubishi Chemical Corporation)
-PTMG with a number average molecular weight of 850 and a hydroxyl value of 132 mgKOH / g (trade name “PTMG850” manufactured by Mitsubishi Chemical Corporation)

(2) Polyether polyols: polyether polyols having a number average molecular weight of 700, an average number of functional groups of 3, and a hydroxyl value of 240 mgKOH / g (trade name “Actol T-700” manufactured by Mitsui Chemicals, Inc.)
-Polyether polyol having a number average molecular weight of 400, an average number of functional groups of 3, and a hydroxyl value of 400 mgKOH / g (trade name “Actol T-400” manufactured by Mitsui Chemicals, Inc.)
-Polyether polyol (trade name “ACTCOL D-2000” manufactured by Mitsui Chemicals, Inc.) having a number average molecular weight of 2000, an average number of functional groups of 2, and a hydroxyl value of 56 mg KOH / g
A polyether polyol having a number average molecular weight of 200, an average number of functional groups of 2, and a hydroxyl value of 560 mg KOH / g (product name “PEG # 200” manufactured by Lion Corporation)

(3) Polyester polyols ・ Polyester polyols with a phthalic acid having a number average molecular weight of 750 and a hydroxyl value of 150 mgKOH / g as an initiator (trade name “Maximol RLK-035” manufactured by Kawasaki Kasei Kogyo Co., Ltd.)
・ Polyester polyol using phthalic acid with a number average molecular weight of 560 and a hydroxyl value of 200 mgKOH / g as an initiator (trade name “Maximol RLK-085”, manufactured by Kawasaki Kasei Kogyo Co., Ltd.)
・ Polyester polyol using phthalic acid with a number average molecular weight of 450 and a hydroxyl value of 250 mgKOH / g as an initiator (trade name “Maximol RLK-065” manufactured by Kawasaki Kasei Kogyo Co., Ltd.)
・ Polyester polyols with adipic acid having a number average molecular weight of 1000 and a hydroxyl value of 115 mgKOH / g as an initiator (trade name “Teslac 2464” manufactured by Hitachi Chemical Co., Ltd.)

(4) Polyhydric alcohol / number average molecular weight 92, average functional group number 3, hydroxyl value 1827 mgKOH / g dipropylene glycol / number average molecular weight 134, average functional group number 2, hydroxyl value 836 mgKOH / g glycerin

○ Foaming agent, water (ion exchange water)
・ Methylene chloride

○ Foam stabilizers and organosilicone surfactants (trade name “SH-193” manufactured by Toray Dow Corning Co., Ltd.)

○ Catalyst / Catalyst A: Tertiary amine-based catalyst; Dipropylene glycol solution containing 33% triethylenediamine (trade name “Kao Riser No. 31” manufactured by Kao Corporation)
・ Catalyst B: Tertiary amine catalyst; Bisdimethylaminoethyl ether (trade name “TOYOCAT-ET” manufactured by Tosoh Corporation)

○ Isocyanate compound · Crude MDI with NCO content of 31.5% (trade name “COSMONATE M-200” manufactured by Mitsui Chemicals, Inc.)
・ Crude MDI with NCO content of 24.8% (trade name “COSMONATE MC-82” manufactured by Mitsui Chemicals, Inc.)
・ TDI with NCO content of 48.3% (trade name “COSMONATE T-80” manufactured by Mitsui Chemicals, Inc.)

The raw materials of the polyurethane foams of Examples and Comparative Examples shown in Tables 1 and 2 were mixed, stirred, and discharged onto a belt conveyor. While moving on the belt conveyor, the raw material naturally foamed at room temperature and atmospheric pressure, and reacted to produce a foam continuously.
Thereafter, it was cured (cured) in a drying furnace to obtain a polyurethane foam having a long block shape (width: about 1000 mm, height: about 50 mm).

About each obtained polyurethane foam, foam property, the presence or absence of a scorch, density (kg / m < ³ >), C hardness, elongation (%), bending resistance, and shape memory property were evaluated. The results are also shown in Tables 1 and 2.

Regarding the “foam properties” and “presence / absence of scorch”, the obtained block-like urethane foam was cut into a predetermined length, and the foam cut surface was visually evaluated.
・ As for the foam properties, normal foam is formed and the cell size is uniform and well-prepared as “good”, and the cell size is uneven and sparse as “cell rough”. In comparison, the foam was slightly shrunk with time but had no problem in use, and “slightly shrunk”.
・ For the presence or absence of scorch, “○” indicates that there was no scorch, and “×” indicates that the scorch occurred.

Regarding "density", "C hardness", "elongation", "bending resistance", and "shape memory", each of urethane foam samples cut to a size of 300 mm length x 300 mm width x thickness 8 mm. Measured according to the following method.
The density (kg / m ³ ) was measured based on JIS K7222.
-C hardness was measured with Asker rubber hardness meter C type.
-Elongation (%) was measured under 25 degreeC, 50 degreeC, and 80 degreeC based on JISK6400-5.

-Regarding the bending resistance, the behavior when each sample was bent 180 ° at room temperature was observed.
“○” indicates that no cracks (cracks or cracks) are generated even when bent 180 °, “△” indicates that there are no cracks (divided into two), and there is no problem in use. What was cracked (divided in two) during bending (about 60 to 120 ° C.) was designated as “x”.
-The shape memory property was tested only for the case where the evaluation of the bending resistance was "○" or "△";
Each sample was allowed to stand for 2 minutes in an atmosphere of 100 ° C., and then bent by 180 ° in the atmosphere. The temperature was lowered to room temperature (25 ° C.) while being pressed in the 180 ° folded state, and the press was released after standing at room temperature for 1 minute, and the state after standing for 1 minute after release was observed.
Those holding the bent angle of 150 ° or more and 180 ° or less were “折 り”, those holding a state of 120 ° or more and less than 150 ° were “◯”, and those holding a state of 60 ° or more and less than 120 ° were kept. The thing was "△", and the thing which returned to less than 60 degrees was set to "x".

  From Table 1, the polyurethane foams of Examples 1 to 13 in the invention of the present application were expressed at a high temperature without causing scorch and exhibiting good folding resistance while having a desired density and hardness (bending) It was found that the shape has excellent shape memory property that it can be maintained even after returning to room temperature.

On the other hand, as shown in Table 2, Comparative Examples 1 to 3 in which the average hydroxyl value of the polyol compound was too high and Comparative Example 4 using TDI could not suppress scorch, and the desired hardness was not obtained.
In Comparative Example 5, a good foam was obtained, but because of the use of crude MDI having an NCO content of 24.8%, the C hardness was low and the shape memory property was inferior.
In Comparative Example 6 using PTMG having a molecular weight of less than 1000 and a hydroxyl value exceeding 112 mgKOH / g, and Comparative Example 7 using a polyether polyol having a molecular weight of less than 300 and a hydroxyl value exceeding 560 mgKOH / g, the foam shrinks. As a result, scorch and density could not be evaluated.
In Comparative Example 8 in which the average hydroxyl value of the polyol compound is too low, a polyether polyol having a molecular weight of more than 1000 and a hydroxyl value of less than 156 mgKOH / g is used, cell roughness cannot be suppressed, and C hardness is low. The bending resistance was not expressed.
Comparative Example 9 in which the average hydroxyl value of the polyol compound is too high uses a polyester polyol having a molecular weight of less than 500 and a hydroxyl value of more than 200 mgKOH / g, cannot suppress scorch, has high C hardness, and has high bending resistance. Not expressed.
In Comparative Example 10, polyester polyol using adipic acid as an initiator was used, and cell roughness could not be suppressed, and although C hardness was low, elongation was poor and bending resistance was not expressed.

  The polyurethane foam of the present invention is lightweight (low density) and high hardness, and has both excellent shape followability (bending resistance) and shape memory. In particular, it is extremely useful in the field of molded products such as automobile ceiling substrates that are required.

Claims (1)

A polyurethane foam obtained by reacting a polyol component containing a polyol compound, a foaming agent, a foam stabilizer, and a catalyst with an isocyanate component,
The polyol compound has (i) a polytetramethylene ether glycol and / or a derivative thereof having a number average molecular weight of 1000 to 3000 and a hydroxyl value of 37 to 112 mgKOH / g, and (ii) a number average molecular weight of 300 to 1000 and a hydroxyl value of At least 4 of a polyether polyol of 156 to 560 mg KOH / g, (iii) a polyester polyol having a number average molecular weight of 500 to 1300 and a phthalic acid having a hydroxyl value of 100 to 200 mg KOH / g as an initiator, and (iv) a polyhydric alcohol. Including seeds and having an average hydroxyl value of 190-300 mg KOH / g,
The (i) polytetramethylene ether glycol and / or derivative thereof is 10 to 20 parts by weight, the (ii) polyether polyol is 40 to 50 parts by weight, and the (iii) polyester polyol with respect to 100 parts by weight of the polyol compound. Is 25 to 35 parts by weight, (iv) the polyhydric alcohol is 5 to 15 parts by weight, and
The isocyanate component is crude MDI having an NCO content of 28-33%.
Polyurethane foam characterized by being.