JPH0751292B2 - Method for producing polyurethane foam molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides a polyurethane foam molded article which is lightweight and has excellent heat insulating effect, sound absorbing effect, vibration noise preventing effect, and rigidity capable of retaining a shape. To a method of manufacturing.

(Prior Art) Flexible polyurethane foam is mainly made of continuous ventilation holes, but has a part of independent pores. It has a sound absorbing effect, a vibration noise preventing effect, a heat insulating effect, and is lightweight, so various moldings are possible. It is used as a product.

Conventionally, such a flexible polyurethane foam molded article is manufactured by injecting a raw material into a foaming mold having a mold surface having a product shape and foaming it into a mold surface shape.

(Problems to be Solved by the Invention) By the way, in the production of flexible polyurethane foam, good foam cannot be obtained unless the foaming reaction and the curing reaction are balanced. However, in the foaming mold, the free foaming is hindered by the shape of the mold surface, so that the balance between the foaming and the curing reaction is easily lost, and this tendency is remarkable especially in the case of a complicated mold surface shape. Therefore, there has been a problem in the related art that only a molded product having a simple shape can be manufactured.

Further, the flexible polyurethane foam molded product obtained by the method has low rigidity and poor shape-retaining property, and therefore is not suitable for use in which self-shape retention is required. Therefore, if it is intended to obtain a shape-retaining one, it is necessary to install a metal insert in the foaming mold to carry out foaming, and the balance between foaming and curing reaction is more likely to be lost. Moreover, there is a problem that the obtained molded product becomes heavy and expensive due to the use of the metal insert.

The present invention has the problems that the prior art has, that is, a molded product having a complicated shape cannot be obtained, and a molded product that is lightweight and has a rigidity capable of retaining a shape cannot be obtained. It is a solution.

(Means for Solving Problems) The present invention relates to a first foam obtained by impregnating a flexible polyurethane foam with a moisture-curable liquid having an NCO group at a terminal, and a second foam comprising a flexible polyurethane foam. Are laminated via a reinforcing material and the laminate is placed in a molding die, or a hot melt film and a release paper are placed in this order on at least one of the upper and lower surfaces of the laminate, and then the laminate is molded. It is characterized in that the laminate is fixed in shape and bonded and integrated by hot pressing into a predetermined shape.

(Function) By compressing the laminate by hot pressing, the moisture-curable liquid having NCO groups at the ends, which has been impregnated in the first foam, exudes and adheres to the reinforcing material and the surface of the second foam. The moisture-curable liquid having an NCO group at its end has a property of being cured and reacted by the aqueous catalyst solution sprinkled on the first foam, and exhibiting adhesiveness at that time. Moreover, the curing rate increases with heating. Therefore, the laminate hot-pressed into a predetermined shape is fixed in shape and bonded and integrated by curing the moisture-curable liquid having NCO groups at the ends, and becomes a desired molded article. In addition, by sandwiching a release paper or the like together with a laminate in which a hot melt film is arranged on at least one of the upper and lower surfaces, the first or second or first
Also, a hot melt film is welded to the surface of the second foam, and a molded article whose surface is covered with a plastic film is obtained.

The molded product thus obtained is cured by the moisture-curable liquid having an NCO group at its end, whereby the first foam as a whole is cured into a highly rigid plate-like body. On the other hand, in the second foam, the moisture-curable liquid adheres and cures only on the laminated surface with the first foam, so that the pores of the second foam are maintained as they are without being substantially closed. Therefore the second
The pores of the foam exert a heat insulating, sound absorbing and vibration noise preventing mechanism, while the hardening of the first foam imparts rigidity capable of maintaining the shape.

Moreover, the rigidity of the molded product is further enhanced by the reinforcing material between the first foam and the second foam. When surface protection and moisture resistance are desired, the hardening is imparted by the hot melt films on the upper and lower surfaces.

Embodiments The present invention will be described below with reference to the drawings illustrating embodiments.

FIG. 1 is a cross-sectional view showing the process of manufacturing a polyurethane foam molded article according to an embodiment of the present invention. In the figure, 10 indicates a first form and 12 indicates a second form.

The first foam 10 is obtained by impregnating a flexible polyurethane foam with a moisture curing liquid having NCO groups at the ends. As the moisture curable liquid having an NCO group at the terminal, a polyurethane prepolymer having excess isocyanate, polyisocyanate or the like diluted with a solvent such as trichloroethane is used. Although the degree of dilution depends on the viscosity of the moisture-curable liquid and the like, it is usually selected in the range of 1.2 to 3 times. Further, as the flexible polyurethane foam, one having a high proportion of continuous ventilation holes is preferable for facilitating the impregnation with the moisture-curable liquid, and from this viewpoint, a polyether type is preferable. The flexible polyurethane foam that constitutes this first foam has a density of 15 to 26 kg / m ³ and a thickness of ³ to 12 mm.
(Thickness before hot pressing) is preferable.

For the impregnation of the moisture-curable liquid, after the flexible polyurethane foam is continuously dipped in the moisture-curable liquid filled in the impregnation tank, the flexible polyurethane foam is squeezed with a roll to force the moisture-curable liquid. In addition, the impregnation can be carried out easily and continuously by uniformly impregnating and simultaneously removing the excess moisture-curable liquid. The amount of impregnation varies depending on the thickness, density, etc. of the flexible polyurethane foam, or the type of moisture-curable liquid, but is as follows as an example.

First flexible polyurethane foam: polyether type, density 20 kg / m ³ , thickness 10 mm Moisture curable liquid: diphenylmethane-4,4'-diisocyanate (MD
I) is diluted 1.3 times with trichloromethane-Impregnation amount: 700 g / m ² (impregnation amount before hot pressing) The density of the soft polyurethane foam that constitutes the second foam 12 is 28-40 kg / m ³ and thickness Is preferably 4 to 15 mm (thickness before hot pressing). As the flexible polyurethane foam, either a polyether type or a polyester type may be used, but the moisture curable liquid in the first foam 10 may be impregnated into the second foam 12 during hot pressing. From the viewpoint of hindering as much as possible, it is preferable to use polyester foam having a relatively high proportion of independent pores. Also,
In order to enhance the sound absorption of the molded product, it is preferable to provide an uneven pattern on the outer surface of the flexible polyurethane foam. The unevenness is formed by forming a hot melt film on the surface of the flexible polyurethane foam by pressing a hot roll or a hot plate heated to about 30 ° C., and then using a press die having an uneven pattern on the mold surface, a mold temperature of 130 to 230. By pressing the melt film surface of the flexible polyurethane foam at 0 ° C.

The hardness of the flexible polyurethane foam constituting the first foam and the second foam is determined by the use of the molded product and the like. For example, the hardness of the flexible polyurethane foam forming the first foam may be harder than that of the second foam, or vice versa.

Reference numeral 14 is a reinforcing material arranged between the first foam 10 and the second foam 12. The reinforcing material 14 is for enhancing the strength and rigidity of the molded product. As a reinforcing material, 30-100m
A glass fiber having a length of m or a glass fiber having a mat shape, or a non-woven fabric made of nylon, polyester or the like is used.

16 is a hot melt film. This hot melt film is used especially when it is desired to protect the surface of a molded article or to increase moisture resistance. As the hot melt film, various types such as polyolefin type, polyamide type and ethylene vinyl acetate (EVA) are used.

The first form 10 and the second form thus formed
12 is sprinkled with the aqueous catalyst solution on the first foam, and then the reinforcing material 14
, A laminate having hot melt films 16 and 16 arranged on at least one of the upper and lower surfaces thereof, and a release paper or the like sandwiched therebetween, and a heat having a mold surface having a desired molded product shape and heating means. It is sandwiched between press dies 18 and 20 and hot pressed into a die surface shape to produce a molded product. As an example of the conditions at the time of hot pressing, the temperature of the upper mold 18 is 120 to 130 ° C., the lower mold 20 is
Temperature 100 ~ 120 ℃, press pressure 40 ~ 50kg / m ² , press time 3
0 to 40 seconds. As the catalyst aqueous solution, for example, an aqueous solution of triethylenediamine is used.

During the hot pressing, the first foam is compressed, and the moisture curable liquid impregnated in the first foam partially exudes to the laminated surface. The exuded moisture curable liquid adheres to the second foam surface and the reinforcement 14 with little impregnation in the second foam 12 due to its viscosity and the independent pores dispersed in the second foam surface. Then, the moisture-curable liquid in and out of the first foam 10 is cured by the water content of the catalyst aqueous solution and the heat retained in the hot press mold, and the desired shape is obtained by fixing the shape of the laminate and integrally bonding. Goods are formed.
In the case of a laminate in which the hot melt films 16 and 16 are arranged, the hot melt film is first
And the second foam surface is fused and formed into a molded article covered with a plastic film. At this time, it is necessary to sandwich release paper or the like so that the hot melt film does not adhere to the mold surface.

The obtained molded article has a highly rigid plate-like body formed by curing with a moisture-curing liquid in a state where the entire first foam 10 is compressed, and a pore structure before hot pressing is almost maintained. It consists of a laminated integral product with the foam of 2. Therefore, the molded product has excellent heat insulating function, sound absorbing function, and vibration and noise preventing function due to the cell structure of polyurethane foam, and the self-shape can be maintained by the highly rigid plate-shaped body made of the compression hardening of the first foam. It will be possible. In addition, the molded product is further enhanced in rigidity by using the reinforcing material 14, or is excellent in moisture resistance by using the hot melt film 16.

FIG. 2 is a perspective view of a duct 22 used in an automobile air conditioner obtained by implementing the present invention. This duct 22 is a duct half composed of the first foam 10, the second foam 12 and a reinforcing material (not shown).
An adhesive is applied to the peripheral flange portion 28 to bond the 24 and 26 together. 30 is the first form 10
The highly rigid plate-like member 32, which is formed by compression hardening, is composed of the second foam 12. Duct made in this way
The plate body 22 having high rigidity can maintain its own shape. Further, the sound of air passing through the duct 22, the opening / closing sound of the damper, or the vibration noise is reduced by the sound absorbing function and the vibration noise preventing function caused by the second foam. Particularly, when the surface of the second foam 32 is provided with an uneven pattern, the sound absorption curing becomes large. Further, the heat insulating function of the second foam 32 prevents the formation of dew condensation on the duct surface. In addition, the duct 22 is light in weight and is an improvement over all the drawbacks of the conventional duct made of plastic or the like.

(Effects of the Invention) The present invention comprises a first foam formed by impregnating a moisture-effective liquid into a flexible polyurethane foam, and a second foam formed of a flexible polyurethane foam, which are stacked with a reinforcing material, etc. The laminate is hot-pressed into a predetermined shape, and since the reaction in the foaming mold in which the reaction is difficult to balance is unnecessary, a molded product having a complicated shape can be satisfactorily manufactured.

Moreover, the molded product obtained by the practice of this invention is the first
Is a laminate of a highly rigid plate-like body obtained by curing a foam in a compressed state with a moisture-curable liquid, and a second foam in which the function of the reinforcing material and the flexible polyurethane foam is almost unchanged. Therefore, the molded product has a function of a flexible polyurethane foam, that is, a heat insulating function, a sound absorbing function, and a vibration noise preventing function, and has a rigidity and a high strength capable of holding a self-shape and is lightweight.

Thus, the present invention provides a problem that the prior art has, that is, a problem that a flexible polyurethane foam molded article having a complicated shape cannot be obtained, and a flexible polyurethane foam molded article that is lightweight and has a shape-retaining rigidity. It solves all the problems that cannot be solved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a manufacturing process in an embodiment of the present invention, and FIG. 2 is a perspective view of a duct obtained by carrying out the present invention. 10 …… First foam, 12 …… Second foam, 14 …… Reinforcing material, 16 …… Hot melt film, 18,20 …… Heat press type, 19 …… Release paper

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Claims (2)

[Claims] 1. A first foam (10) obtained by impregnating a flexible polyurethane foam with a moisture-curable liquid having an NCO group at its end, and a second foam (12) made of flexible polyurethane foam are reinforced. After stacking them through the material (14) and arranging the laminate in a molding die, or placing a hot melt film (16) and a release paper (19) on at least one of the upper and lower surfaces of the laminate in this order. A method for producing a polyurethane foam molded article, characterized in that the shape of the laminate is fixed and adhesive integration is performed by placing the laminate in a molding die and hot-pressing the laminate into a predetermined shape. 2. The method for producing a polyurethane foam molded article according to claim 1, wherein the second foam has a hot-melt film on one surface and has an uneven pattern on its surface.