JPS5825095B2 - Polyurethane material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously producing polyurethane foam reinforced with long fibers.

Conventionally, long fibers are impregnated with a resin liquid that provides polyurethane, and this is allowed to advance into a molding passage, and the resin liquid is foamed and cured within the molding passage to produce polyurethane foam reinforced with long fibers. It is known to manufacture bodies.

However, the polyurethane resin liquid used in the conventional method generally has a high viscosity, and it is difficult to uniformly impregnate the long fibers with the resin liquid (especially when the number of long fibers used is increased). When trying to obtain a product with a large cross-sectional area, the difficulty of uniform impregnation increases dramatically.

In addition, if the molded product foamed and hardened in the molding passage is not removed from the mold in a sufficiently cooled state, the product will break or crack, so it is necessary to make the residence time in the molding passage sufficiently long. , the molding path is therefore necessarily long.

Furthermore, the heat-resistant temperature of products obtained by conventional methods is too high (and it is desired to further increase the heat-resistant temperature).

In view of the drawbacks of the conventional method, the present invention aims to reduce the viscosity of the resin liquid, facilitate impregnation into long fibers, shorten the cooling time, and improve the heat resistance of the product. This was the result of various studies, and the gist is that polyol resins, vinyl monomers,
At least one vinyl group and at least 1 f[
While a large number of long fibers impregnated with a polyurethane resin liquid containing a compound having a hydroxyl group of ffi and a polyfunctional incyanate are advanced through a molding passage, the polyurethane resin liquid is foamed and cured within the molding passage. A method for producing a long fiber reinforced polyurethane foam is provided.

In the above, polyol resin is a general term for polyol resins that are generally used as raw materials for producing polyurethane and give polyurethane by reacting with polyfunctional incyanate, and those giving hard polyurethane are particularly preferred.

In addition, the vinyl monomer refers to a monomer that has one polymerizable vinyl group in the molecule and is usually used as a raw material for producing synthetic resins, and is preferably liquid at room temperature. .

Examples of vinyl monomers suitably used in the present invention include styrene, vinyl acetate, acrylonitrile, methyl methacrylate, various acrylic esters, etc. In particular, styrene, methyl methacrylate It is more preferable to use

Next, in the present invention, compounds having at least one vinyl group and at least one hydroxyl group in one molecule are used, and preferred examples of the compounds include 2-hydroxyethyl acrylate, 2- Examples include hydroxyethyl methacrylate, an esterified product of fumaric acid and a polyfunctional alcohol, and glycerol dimethacrylate.

Next, the polyfunctional isocyanate refers to an isocyanate compound that is generally used as a raw material in the production of polyurethane, and includes, for example, diphenylmethane diisocyanate, toluene diisocyanate, and the like.

In the present invention, the above-mentioned four types of substances are mixed to form a polyurethane resin liquid, but as for the amount of vinyl monomer used, if the amount used is too small, the viscosity of the polyurethane resin liquid The effect of lowering the temperature and improving the heat resistance of the resulting resin will be reduced, and if the amount is too high, the resulting foam will tend to have rough cells or take a long time to complete polymerization. resin 10
It is preferable to use 5 to 40 parts by weight relative to 0 parts by weight.

In addition, for compounds having at least one vinyl group and at least one hydroxyl group in one molecule, if the amount is too small, the rate at which the vinyl polymer mixed in the polyurethane resin produced will crosslink with the polyurethane resin will decrease. However, since this has an unfavorable effect on the physical properties of the resulting foam, it is preferable to use an amount having a vinyl equivalent equivalent to 10 or more of the total vinyl equivalents of the vinyl monomer used.

Note that even if the above-mentioned compound is used in a large amount, no problem arises in separate installation, but since it is generally expensive, it is preferable to use a small amount in terms of cost.

The amount of polyfunctional incyanate to be used is the total amount of the hydroxyl equivalent of the polyol resin and the hydroxyl equivalent of the compound having at least one vinyl group and at least one hydroxyl group in one molecule ([OH, Let it be l.

) and the incyanate equivalent of the polyfunctional incyanate (
[NGO]

) is CNC0)/[0H)=1.05 to 1.1
It is preferable to use an amount that satisfies the following.

Further, when water is added as a blowing agent for the polyurethane resin liquid, it is preferable to increase the amount of the isocyanate by the amount of incyanate equivalent corresponding to the active hydrogen equivalent.

However, in the present invention, the polyurethane resin liquid impregnated into the long fibers contains the above-mentioned polyol resin, vinyl monomer, 1
The resin liquid contains a compound having at least one vinyl group and at least one hydroxyl group and a polyfunctional incyanate in its molecule, and the resin liquid contains a vinyl monomer therein. , has a low viscosity and is therefore easily impregnated into long fibers.

] In addition to the above, other suitable substances may be added to the resin liquid as necessary.

For example, metal compounds such as tin that promote the reaction between isocyanate groups and hydroxyl groups, catalysts such as tertiary amines, peroxides that initiate polymerization of vinyl monomers, polymerization catalysts such as azobisisobutyronitrile, and trichloride. It is preferable to add an easily volatile substance such as fluoromethane or a foaming agent such as water, and in addition, a foam stabilizer such as a surfactant to make the bubbles fine or a coloring agent may be added.

Next, the long fibers used in the present invention may be thread-like fibers made by intertwining short fibers (or may be monofilaments).

In short, the long fibers may be continuous long fibers.

The long fibers may be glass fibers or carbon fibers, natural fibers such as cotton or linen, or synthetic fibers such as polyamide, polyester, or polyolefin.

However, it is preferable to use glass fibers for the purpose of reinforcing the molded object by integrating the long fibers with the resin.

Furthermore, the forming passage in the present invention refers to a cylindrical body having a cross-sectional space corresponding to the cross-sectional shape of the intended molded body, and the material thereof may be wood, metal, or other material that does not easily deform. Bye.

The inlet and outlet portions of the molding passage may be slightly tapered to facilitate removal of the molded product from the outlet.

However, the resin liquid impregnated into the long fibers in the molding passage foams and hardens to form a molded body having a shape corresponding to the cross section of the molding passage. should be determined by taking into consideration the curing and cooling rate of the resin liquid and the advancement speed of the long fibers. However, it is important to keep the erosion length as short as possible in order to reduce the resistance in the molding path of the molded product. Few (
It is preferable to do so.

Moreover, at least one wall surface of the molding passage may be constituted by an endless belt.

A device for heating or cooling the resin liquid-impregnated long fibers or the foamed and hardened molded product traveling in the passage may be provided at an appropriate outer peripheral portion of the molding passage.

Next, the method of the present invention will be explained step by step.

First, the long fibers are impregnated with the polyurethane resin liquid, and this impregnation is progressing with a large number of long fibers bundled together, and a fixed amount of the polyurethane resin liquid is sprinkled with a spraying device. This is done by, for example,

In this impregnation step, it is necessary to uniformly disperse the resin liquid in the long fiber bundle in order to obtain a molded article in which the long fibers are uniformly dispersed in the foam. The polyurethane resin liquid used for this purpose has a low viscosity because it contains vinyl monomers, and uniform impregnation can be easily achieved.

Further, in order to make impregnation with the resin liquid more uniform, the long fibers impregnated with the resin liquid can be rubbed or vibrated using an appropriate device.

Next, the long fibers impregnated with the polyurethane resin liquid as described above are passed through a molding passage, where the resin liquid is foamed and hardened.

The above-mentioned foaming may be carried out using commonly used blowing agents such as readily volatile substances or pyrolyzable blowing agents, or by using water and generating carbon dioxide gas by reaction with polyfunctional incyanate. You can go.

The resin liquid foamed in this way is then cured, and during this curing, the polyol resin and polyfunctional incyanate contained in the resin liquid are heated and reacted with hydroxyl groups and incyanate groups. In the presence of a catalyst to promote the reaction, the reaction becomes a polyurethane resin, and at this time, compounds containing at least one vinyl group and at least one hydroxyl group in one molecule contained in the resin liquid also have a hydroxyl group of the compound. By reacting with a polyfunctional incyanate, it is incorporated as a building block into the resulting polyurethane resin.

On the other hand, the vinyl monomer contained in the resin liquid does not react directly with the polyol resin or polyfunctional isocyanate, but does react with the vinyl group of the compound incorporated into the polyurethane resin as described above. It reacts with this and polymerizes, forming crosslinks between polyurethane resin molecules, making the polyurethane resin harder and imparting heat resistance.

The polymerization of the vinyl monomer is promoted by a polymerization catalyst or heat, and when the polymerization of the vinyl monomer is completed, curing in the present invention is completed.

As described above, in the present invention, the foamed polyurethane resin liquid first reacts with the polyol resin contained in the resin liquid and the polyfunctional isocyanate to produce a polyurethane resin, and at the same time, at the same time, at least A compound having one vinyl group and at least one hydroxyl group is incorporated, and then the vinyl group in the compound is contained in a polyurethane resin liquid and reacts with a ruhinyl monomer, so that the vinyl monomer is polymerized, This forms a crosslinked structure between polyurethane molecules in the polyurethane resin.

In this way, the polyurethane resin liquid is foamed and cured in the molding passage to obtain a long fiber-reinforced polyurethane foam in which the long fibers are uniformly dispersed. It is continuously manufactured by being pulled out from the molding path at a constant speed by the drive of the provided pulling device.

As described above, in the method for producing a long fiber-reinforced polyurethane foam of the present invention, the specific polyurethane resin liquid containing a vinyl monomer is used as the resin liquid to be foamed and cured in the molding passage. Because of this, the viscosity of the resin liquid can be lowered, so that long fibers can be easily impregnated (and can be impregnated more uniformly).

In addition, due to the crosslinked structure produced by the reaction of the vinyl monomer contained in the resin liquid and a compound having a small number (at least one vinyl group and at least one hydroxyl group in one molecule),
The resulting polyurethane resin is harder and has a higher degree of heat resistance, so even if the degree of cooling in the molding path of the resulting foam is lowered and the mold is demolded for a shorter cooling time, it will not crack. or does not cause cracks,
Therefore, the molding passage can be shortened by that much, and the resistance within the molding passage can be reduced, which is advantageous in terms of the manufacturing process.

Furthermore, the resulting product also has improved heat resistance, so it can be used for a wider range of purposes.

In addition, if a vinyl monomer is simply added to the resin solution that provides polyurethane in order to lower the viscosity of the resin solution, the vinyl monomer polymer will be unevenly distributed in the resulting resin, which will have an unfavorable effect on the physical properties. However, in the present invention, by using a compound having a vinyl group and a hydroxyl group in combination, uneven distribution of the vinyl monomer polymer will not occur.

r Examples of the present invention will be described below.

Note that in the following, parts mean parts by weight.

Example 1 and Comparative Example 1.2 A polyurethane resin liquid having the composition shown as Example 1 in Table 1 was used.

In the above table, polyol resin A is a sucrose-based polyether resin having a hydroxyl value of 4600 and a viscosity of 8000 centipoise, and polyol resin B is a pentaerythritol-based polyether resin having a hydroxyl value of 400 and a viscosity of 1850 centipoise.

On the other hand, as long fibers, 200 monofilaments with a thickness of 13 microns were collected to make one strand, and 240 of these strands were further collected to make 10-bing, and 300 glass fibers were collected and used at a traveling speed of 0.5 m/min. proceeded continuously.

The resin liquid shown in Table 1 is sprinkled on the progressing glass fibers at a rate of 2.7 kg/min from the nozzle of the resin liquid supply device, and then the glass fibers are rubbed between two plates to impregnate them with the resin liquid. I helped.

The resin liquid-impregnated long fibers thus obtained were introduced into the molding path at the above-mentioned speed.

The molding passage is composed of four endless bells, and has a length of 100 mm, a width of 150 mm, and a length of 12 m.
The passage has a cylindrical space, and an electric heater is installed in the area 4m to 8m from the entrance to heat the inside to 120°C, and a water tank for cooling is installed in the area 8m to 12m from the entrance. is provided.

Note that the long fibers were advanced by driving a take-up device provided at the front in the advancing direction.

The polyurethane resin liquid impregnated with the long fibers in the molding passage foams and hardens to obtain a foam in which the long fibers are uniformly dispersed, but when it comes out of the molding passage there are no cracks or cracks. There wasn't.

In this way, a long fiber-reinforced polyurethane foam body having a cross section of 100 mm x 150 mm was obtained.

When we measured the heat distortion temperature of this product, it was 103℃.
Met.

On the other hand, a long fiber-reinforced foam was produced in the same manner as above using the composition listed as Comparative Example 1 in Table 1, but in this case, the viscosity of the polyurethane resin liquid was high and impregnating the long fibers was difficult. was not uniform, and a good product could not be obtained.

Furthermore, when a long fiber reinforced foam was produced in the same manner as in Example 1 using the composition listed as Comparative Example 2 in Table 1, impregnation with the polyurethane resin liquid was somehow achieved; Cracks occurred at the point where the molded product exited the molding path due to insufficient cooling.

The heat distortion temperature of the obtained product was measured and was 87°C.

Claims (1)

[Claims] 1 A large number of long fibers impregnated with a polyurethane resin solution containing a polyol resin, a vinyl monomer, a compound having at least one vinyl group and at least one hydroxyl group in one molecule, and a polyfunctional isocyanate. A method for producing a long fiber-reinforced polyurethane foam, which comprises foaming and curing the polyurethane resin liquid in the molding passage while advancing the same in the molding passage.