JP5500519B2 - Method for producing foamed urethane composite molded product and foamed urethane composite molded product - Google Patents

Description

The present invention relates to a method for producing a urethane foam composite molded article and a urethane foam composite molded article.

Conventionally, foamed urethane molded products having a high-density surface layer have been used for various purposes such as building materials, furniture, and household electrical appliance cabinets. This foamed urethane molded article is usually subjected to urethane foaming in a mold made of silicon resin, and finished to correct pinholes, voids and the like on the surface after taking out (for example, Patent Documents 1 to 4).

JP 59-13723 A Japanese Patent Publication No. 63-30923 JP 59-168020 A Japanese Examined Patent Publication No. 4-21690

However, in the above-mentioned conventional manufacturing method, when urethane foaming is performed in a silicon rubber mold, a barrier coat is applied to the silicon rubber mold and a strong solvent is used. Work often needs to be done. When urethane foaming is performed in a mold other than silicon rubber, a release agent is applied. As described above, there is a problem that the work is troublesome and the life of the mold is shortened, which is not economical. In addition, there is also a problem that it takes a lot of work to finish the molded product, requiring skillful work such as pinholes on the surface of the foam, putty repair of voids, sandpaper polishing, etc.
Further, the quality of the foamed urethane molded product produced in this way still has a problem that the surface thereof is damaged or damaged due to a light impact.

The object of the present invention is to provide a production method for improving various process problems when a conventional mold is used, and to be used in place of a conventional urethane foam molded article having a high-density surface layer. It is to provide a foamed urethane composite molded article having improved scratch resistance.

  As a result of earnest research, the present inventors set a mold formed by vacuum molding of a specific resin in a mold, foamed urethane in the mold, and demolded after completion of foaming. Then, the present inventors have found that the above problems can be solved, and have reached the present invention.

That is, the invention of claim 1 is to manufacture a skin mold by vacuum molding a sheet of thermoplastic hard resin, set the skin mold in a mold of the same type as the skin mold, in demolding each epidermis formwork from the mold after the urethane foam, the method for producing a skin mold and the foamed urethane composite molded foamed urethane are integrated, thermoplastic hard resin is an acrylic modified vinyl chloride resin And the urethane foam has a foaming ratio of 30 to 50 times .

According to the invention of claim 1, urethane foaming is performed in a hard skin mold that has been vacuum-formed in advance, and the hard skin mold is taken out as it is, so that it is not necessary to apply a barrier coat to the mold, and a strong solvent or a release agent is used. It is unnecessary to use, and the process is simplified and economical. Further, since the surface of the urethane foam composite molded product is not a urethane foam but a surface of a thermoplastic hard resin, there are no pinholes, voids, etc., and there is no need for skilled work such as repair and sandpaper polishing.
In addition, since it is a foamed urethane composite molded product with good adhesion between the hard skin and foamed urethane, and the skin and foamed urethane integrated, it should be used in place of the conventional foamed urethane molded product with a high-density surface layer. And a urethane foam composite molded article having improved surface scratch resistance.

The surface of the skin mold form obtained by vacuum-molding a thermoplastic hard resin sheet is hard and the shape is maintained only by the skin. Therefore, the shape of the molded product should be maintained even if the foamed urethane is expanded 30 to 50 times. Can do. When the expansion ratio is 30 times or more, there is an economic merit than conventional foamed urethane molded products having a high-density surface, and general use is possible. There is no problem as a skin and the performance of urethane foam such as heat insulation can be secured. In addition, the foaming ratio of the conventional urethane foam molded article having a high-density surface layer is 10 to 20 times, but can be increased to 30 to 50 times in the method of the present invention. 3 can be reduced in weight.

Since the thermoplastic hard resin is fat acrylic modified vinyl chloride tree, with adhesion to the inside of the urethane foam is further excellent, moldings having a small radius of curvature pinholes even at bent portions of, such as cracks were excellent not occur The surface finish. Moreover, it has good impact resistance, toughness, and weather resistance, and can be used for a long time even when used for exteriors.

The invention of claim 2 is manufactured by the method of claim 1 wherein the urethane foam molded composite article according, the front surface is urethane foam composite molded article formed is covered with the skin of the acrylic modified vinyl chloride resins.

According to the invention of claim 2, the foamed urethane composite molded product produced by the method for producing the foamed urethane composite molded product of claim 1 is obtained by integrating the hard skin of the thermoplastic hard resin and the foamed urethane inside. It is used in place of a conventional urethane foam molded article having a high-density surface layer, and the surface scratch resistance is further improved. When the thermoplastic hard resin is an acrylic-modified vinyl chloride resin, in addition to improved adhesion to foamed urethane and scratch resistance, the finish of the bent portion and weather resistance are also good.

The method for producing a foamed urethane composite molded product of the present invention and the obtained foamed urethane composite molded product have the following effects.
(1) It is not necessary to apply a barrier coat to the mold, and it is not necessary to use a strong solvent or a release agent, and the process is simplified and economical.
(2) There are no pinholes, voids, etc. on the surface of the urethane foam molded article, and there is no need for skilled work such as repair and sandpaper polishing.
(3) Adhesiveness between the hard skin and urethane foam is good, and it becomes a urethane foam composite molded product in which the skin and urethane foam are integrated, and it can be used in place of a conventional urethane foam molded product having a high-density surface layer. At the same time, the scratch resistance of the surface is improved.
(4) When the foaming urethane is expanded by 30 to 50 times, the weight can be reduced to 1/2 to 1/3 of the conventional one.
(5) When the thermoplastic rigid resin is fat acrylic modified vinyl chloride trees, adhesion to the urethane foam, in addition to abrasion resistance is improved, further bent portion of the finish, is good weatherability .

Embodiments of the present invention will be described below. Note that the present invention is not limited to the following embodiments. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

The thermoplastic hard resin used in the present invention is not limited as long as it is a thermoplastic hard resin having crystallinity, but is an acrylic / styrene / acrylonitrile solution, acrylonitrile / butadiene / styrene copolymer (ABS). , Acrylonitrile / ethylene-propylene-diene / styrene copolymer (AES), methacryl / styrene copolymer, acrylic resin, acrylic modified vinyl chloride resin, nylon resin, butylene terephthalate resin, ethylene terephthalate resin, styrene resin, styrene -A resin selected from an acrylonitrile solution and a carbonate resin is preferred. In the present invention, the term “hard” means that the surface is hard at 50 ° C. or less and has scratch resistance, and that even a thin layer molded product maintains its shape. When foaming conventional polyurethane in a mold, soft polyurethane has been used as the skin. If the skin was not polyurethane, the adhesion with the internal urethane foam was poor, and pinholes, voids, and cracks occurred in the bent portions of the skin. In other words, the bent portion is stretched more than other portions during vacuum forming, so that the thickness of the bent portion becomes thin, and cracks are likely to occur due to the foaming pressure of urethane foam. However, surprisingly, it has been found that when a hard resin, particularly the resin exemplified above is used, pinholes and cracks are hardly generated even at the bent portion. That is, even if the curvature radius of the bent portion of the epidermis is about 1 mm, pinholes and cracks are not seen in the bent portion. This means that when these resins are used, in addition to the toughness of the resin, the affinity between the polar group on the top surface of the new resin and the NCO group of the urethane resin, which is generated when the resin is thinned, It is also presumed that one of the reasons is that the adhesion with the resin is improved by the reaction between the active hydrogen of the resin and the unreacted NCO group.

Of these, acrylonitrile / ethylene / propylene / diene / styrene copolymer (AES) and acrylic modified vinyl chloride resin, which have good weather resistance and toughness as the skin, are particularly preferable. Further, even if the radius of curvature of the bent portion is about 0.2 mm, pinholes and cracks are not seen, and the finish is excellent in detail. It can be estimated that these resins are particularly excellent because they have excellent impact resistance and toughness in addition to adhesion to urethane. As the acrylic-modified vinyl chloride resin, a commercially available product “KAIDAC” (registered trademark, manufactured by Sumitomo Bakelite Co., Ltd.) can be suitably used.

In the present invention, the thermoplastic hard resin sheet used for vacuum forming as a skin mold is well stretched at a vacuum forming temperature (preferably 170 to 200 ° C.) and formed into a three-dimensional three-dimensional curved surface. In addition, it is required as a characteristic that the stretched portion does not contract. If there is a plasticizer in the sheet, the smaller the amount of plasticizer, the smaller the shrinkage of the sheet, but the elongation during vacuum forming becomes worse and the hardness decreases. A sheet having no plasticizer is preferred. The thickness of the sheet used is preferably 1 mm or more and 3 mm or less. When the thickness is 1 mm or more, the bent portion after vacuum forming becomes thin and no pinholes or cracks are generated. At the same time, the shape retention is good. The time does not increase, the moldability is good, it is not necessary to make it thicker, and it becomes economical.

The thermoplastic hard resin used in the present invention includes other inorganic fillers such as talc and mica as required, and known antioxidants, neutralizers, lubricants and antistatic agents used in general thermoplastic resins. , Pigments and the like can be added.

As the raw material of the foamed urethane foamed in the skin mold, those usually used in the urethane foam can be used, and the foam raw material containing polyol, polyisocyanate, crosslinking agent, foaming agent, catalyst, foam stabilizer, etc. Reaction and foaming.
As the polyol, those usually used for polyurethane are used, and examples thereof include polyether polyols, polyester polyols, castor oil, and polymer polyols obtained by polymerizing vinyl monomers in these polyols. Although the valence and molecular weight of the polyol are not particularly limited, those described as the crosslinking agent described later are excluded.

As polyisocyanate, what can be normally used for polyurethane is used. For example, an aromatic polyisocyanate having 6 to 20 carbon atoms (excluding the carbon number in the NCO group) [2,4-, 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4′-, 4, 4′-diphenylmethane diisocyanate (MDI), crude MDI, polyaryl polyisocyanate (PAPI), etc.]; aliphatic polyisocyanate having 2 to 18 carbon atoms [hexamethylene diisocyanate, lysine diisocyanate, etc.]; alicyclic ring having 4 to 15 carbon atoms Formula polyisocyanates [isophorone diisocyanate, dicyclohexyl diisocyanate, etc.]; aromatic aliphatic polyisocyanates having 8 to 15 carbon atoms [xylylene diisocyanate, etc.]; modified products of these polyisocyanates [urethane group, carbodiimide group, allophanate group, urea group , Bi Uretto, uretdione, uretonimine groups, isocyanurate groups, and oxazolidone group-containing modified products, etc.] and combinations of two or more of these. Among these, preferred are TDI, MDI, crude MDI, carbodiimide group-containing modified MDI, and combinations of two or more thereof.

Examples of the crosslinking agent include polyhydric alcohols, polyhydric phenols, alkanolamines, polyamines such as polyhydric alcohols such as ethylene glycol and diethylene glycol; alkanolamines such as triethanolamine and diethanolamine, and these crosslinking agents may be used alone or in combination. Can be used.
Examples of the foaming agent include known ones such as pentane, cyclopentane, hexane, cyclohexane, dichloromethane, and carbon dioxide in addition to water.

The catalyst is for accelerating the urethanation reaction between a polyol and a polyisocyanate. For example, a tertiary amine such as N, N ′, N′-trimethylaminoethylpiperazine, triethylenediamine, dimethylethanolamine, octylic acid Organic metal compounds such as tin (tin octoate), acetates, alkali metal alcoholates and the like can be used.
Examples of the foam stabilizer include anionic surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, polyether siloxane, and phenolic compounds. In addition, flame retardants can be used as necessary.

The urethane foam in the present invention may be soft, semi-rigid, or hard, and can be changed depending on the application. It can be obtained by changing.

The urethane foam composite molded article of the present invention is a vacuum-molded sheet of a thermoplastic hard resin to produce a skin mold, and the skin mold is set in a mold of the same type as the skin mold. After urethane foaming is performed, the entire skin mold is removed from the mold.

First, a thermoplastic hard resin sheet is set in a vacuum forming apparatus, and a thin layer molded product to be a skin mold is produced under a normal vacuum press condition at a temperature of 170 to 200 ° C., for example. The skin mold must have a recess that allows urethane foaming. The layer thickness of the skin mold is preferably 0.3 to 0.8 mm. If it is 0.3 mm or more, the bent portion is not too thin and pinholes, voids, and cracks are less likely to occur in the bent portion. When the thickness is 0.8 mm or less, the molding is finished satisfactorily, and it is not necessary to make it thicker, which is economical. Moreover, it is preferable that a curvature radius is 1 mm or more in the bending part of an outer_skin | epidermis. If it is 1 mm or more, pinholes and cracks are unlikely to occur in the bent portion. A commercial product can be used for the vacuum forming apparatus.

Next, in order to perform urethane foaming, it is set in a mold having the same type as the skin mold. The mold is preferably a silicon mold. If it is a silicon rubber mold, it is easy to remove after urethane foaming. However, since each skin mold is removed, it is not necessary to apply a barrier coat or a release agent to the silicon mold. The reason why it is set in the same mold is that an excessive load due to urethane foaming is applied to the local part of the skin mold and no cracks are generated.
When the setting is completed, it is sealed in the skin mold and the inside is set to a predetermined temperature. Next, the raw material mixture of urethane foam is poured into the skin mold.
The method for injecting the polyurethane foam raw material into the closed mold is not particularly limited, and the polyurethane foam raw material is injected under conditions usually used.

For urethane foaming, a one-shot method or a prepolymer method is usually employed. The one-shot method is a method in which a polyol and polyisocyanate are directly reacted. The prepolymer method is a method in which a part of a polyol and a polyisocyanate is reacted in advance to obtain a prepolymer having an isocyanate group or a hydroxyl group at a terminal, and the polyol or polyisocyanate is reacted therewith. The one-shot method is a preferable method because the manufacturing process is one step compared to the prepolymer method, and there are few restrictions on the manufacturing conditions, and the manufacturing cost can be reduced.

As a method for suppressing urethane foam, a press method or a clamp method can be applied, but a clamp method in which a mold angle can be freely set is preferable.

As for the expansion ratio, low foaming to high foaming is possible, but even if the internal foamed urethane is expanded to 30-50 times, the skin is hard and the shape of the molded product can be maintained, and the foamed urethane such as heat insulation can be maintained. Since a molded product having characteristics is obtained, an expansion ratio of 30 to 50 times is preferable. When the expansion ratio is 30 times or more, an economical merit can be obtained as compared with a conventional urethane foam molded article having a high-density surface layer, and it can be generalized. When it is 50 times or less, it is possible to foam urethane inside, and to ensure the performance of urethane foam such as heat insulation. Moreover, although the foaming ratio of the conventional urethane foam is 10 to 20 times, it can be reduced to 30 to 50 times in the method of the present invention, so the weight can be reduced to 1/2 to 1/3 of the conventional one. When the foaming ratio of urethane foam is high, the foaming pressure increases accordingly, and cracks occur in the bent portion where the film thickness is thin, and the urethane tends to leak. However, in the production method of the present invention, cracks do not occur in the bent portion even at an expansion ratio of 30 to 50 times. This is unthinkable for conventional urethane foam products.

Cool out after foaming urethane. Then deburr and finish. Conventionally, work that required skill such as pinholes on the surface of urethane foam, putty repair such as voids, sandpaper polishing, etc. was performed, but in the manufacturing method of the present invention, such work is not necessary and the process Can be simplified.

Example 1
Set a sheet of thermoplastic hard resin of “Kydak # 3000” (registered trademark, acrylic modified vinyl chloride resin, Sumitomo Bakelite Co., Ltd.) with a thickness of 2 mm in a vacuum molding machine (“CUPF-1015-PWB” manufactured by Fuse Vacuum Co., Ltd.) Then, vacuum molding was performed for 2 minutes at 180 ° C. and a pressure of 3.0 kg / cm ² to prepare a layered molded product having a recess. No pinholes or cracks occurred even when the radius of curvature of the bent portion was 0.2 mm. The film thickness of the planar portion was 0.5 mm. Next, it was set in the same type of silicon mold (not coated with a barrier coat) and sealed, and a foaming raw material mainly composed of polyether polyol and TDI was injected by the one-shot method to foam urethane. The injection conditions were a liquid temperature of 25 ° C., a circulation pressure of 3.5 kg / cm ² , a discharge pressure of 3.5 kg / cm ² , and an injection amount of 200 g / second. Foaming magnification was 40 times. After 20 minutes, the mold was removed and taken out, deburred and finished to obtain a foamed urethane composite molded product A. The surface was not damaged by the nails. Further, the gloss retention after 1000 hours of the sunshine weatherometer was 95%, and the initial surface state was almost retained.

(Example 2)
In Example 1, urethane foam composite molding was performed in the same manner as in Example 1 except that “Dialac XE60” (registered trademark, AES resin, manufactured by Mitsubishi Chemical Corporation) was used instead of the acrylic-modified vinyl chloride resin as the thermoplastic hard resin. Product B was obtained. The surface was not damaged by the nails. Further, the gloss retention after 1000 hours of the sunshine weatherometer was 93%, and the initial surface state was substantially retained.

(Comparative Example 1)
The silicon mold was heated to 30 to 40 ° C., the barrier coat was applied to the silicon mold, and after 3 to 5 minutes, the same urethane raw material as used in Example 1 was injected to perform foaming. After 20 minutes, it was demolded to produce a urethane foam product having a high-density surface layer. The expansion ratio was 15 times . We repaired pinholes and voids on the foam-resistant surface and polished the surface with sandpaper. The surface was scratched with nails. In addition, cracks occurred on the surface after 500 hours of the sunshine weatherometer.

(Comparative Example 2)
In Example 1, a urethane foam composite molded article C was obtained in the same manner as in Example 1 except that a polypropylene sheet (manufactured by Nippon Polypro Co., Ltd.) was used instead of the acrylic-modified vinyl chloride resin as the thermoplastic hard resin. When removing from the mold, the urethane foam peeled off from the skin mold and was not integrated.

The urethane foam composite molded article of the present invention can be suitably used as an alternative to a polyurethane foam molded article having a high-density surface layer. For example, it is used for applications such as automobile parts, furniture parts, exterior building materials.

Claims (2)

A sheet of thermoplastic hard resin is vacuum molded to produce a skin mold, the skin mold is set in the same mold as the skin mold, and urethane foaming is performed in the skin mold after the mold. In a method for producing a foamed urethane composite molded product in which a skin mold and an urethane foam are integrated, the entire surface mold is removed from the mold, the thermoplastic hard resin is an acrylic-modified vinyl chloride resin, and the foaming ratio of the urethane foam Is 30-50 times, The manufacturing method of the urethane foam composite molded product characterized by the above-mentioned. Claim 1 is prepared in urethane foam composite molded process according urethane foam composite molded article front surface is covered with the skin of the acrylic modified vinyl chloride resins.