JPH08157635A - Production of expansion molded thermoplastic polyurethane article - Google Patents

Abstract

PURPOSE: To easily produce the subject molded article having beautiful surface and high expansion ratio, containing uniform closed cells and useful for heat- insulation material, cushioning material, etc., in one stage by heating and melting a thermoplastic polyurethane resin, dispersing a specific foaming agent in the molten resin and extruding the mixture into atmosphere to effect the expansion molding of the resin. CONSTITUTION: This molded article is produced by heating and melting (A) a thermoplastic polyurethane resin, dispersing (B) a volatile foaming agent having a boiling point of <=20 deg.C (e.g. n-butane or dimethyl ether) in the molten resin under pressure and extruding the mixture through a die into atmosphere to effect the expansion molding of the resin. The amount of the component B is 0.5-20 pts.wt., especially 2-8 pts.wt. based on 100 pts.wt. of the component A. The ratio of the closed cell in the objective molded article is preferably >=60%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic polyurethane foam molding by extrusion foaming. More specifically, the mechanical properties of the thermoplastic polyurethane resin,
The present invention relates to a method for producing a thermoplastic polyurethane foamed molded product by extrusion foaming, which has excellent properties such as abrasion resistance and high impact resilience, has a beautiful surface, and is uniform and fine and has a high closed cell rate.
The foamed molded product of the present invention can be used, for example, as a lightweight molded product, a cushioning material, a vibration damping material, a heat insulating material and the like.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
The polyurethane foam molded article is a method of directly obtaining a foam molded article by subjecting a liquid isocyanate compound and a polyol compound to a urethane-forming reaction and simultaneously foaming them with a low boiling point liquid such as water, chlorofluorocarbon, and methylene chloride as a foaming agent. Was manufactured by. However, in the above method, it is necessary to keep the isocyanate compound, the polyol compound and the foaming agent constant at all times in the case of continuously producing a molded product, so that it is difficult to accurately control the production conditions.

Therefore, as a method for stably and continuously producing a molded body, Japanese Patent Laid-Open Nos. 1-263016 and 1
-230645 and JP-A-5-301988, a pyrolytic foaming agent is uniformly dispersed in advance in a thermoplastic polyurethane resin or a precursor thereof at a temperature at which the foaming agent does not decompose, and then another A method for producing a foamed molded article by melting and mixing the raw material and the foaming agent at a temperature equal to or higher than the decomposition temperature has been proposed. However, in the production methods described in these publications, it is difficult to reduce the production cost because it takes man-hours, the decomposition of the resin is likely to occur, and the obtained foam density is large up to 0.6 g / cc, There are problems such as difficulty in obtaining a low-density foam.

On the other hand, the inventors of the present invention have made diligent efforts to solve the above-mentioned problems, and as a result, the physical foaming agent is uniformly dispersed and kneaded under pressure to the molten thermoplastic polyurethane. After that, cool inside the extruder once within a temperature range that does not develop rubber elasticity, then introduce the molten mixture into the mold, and cool again to the temperature suitable for foaming for foaming near the exit of the mold. After that, it was discovered that a foam having a beautiful surface and uniform cells can be obtained by open-foaming in the air, and the present invention was completed. It is an object of the present invention to provide a method for producing a highly expanded foam having a beautiful surface and uniform cells in one step without preparing a raw material in which the agent is dispersed.

[0005]

Thus, according to the present invention, a thermoplastic polyurethane resin is heated and melted, and an easily volatile foaming agent having a boiling point of 20 ° C. or less is dispersed in the melted resin under pressure, and then the die is formed into a die. A method for producing a thermoplastic polyurethane foam-molded article is provided, which comprises extruding into the air through a foam to form the foam-molded article.

As the thermoplastic polyurethane resin usable in the present invention, any resin synthesized by subjecting an isocyanate compound and a polyol compound to a urethane reaction can be used. Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, and xylene diisocyanate.

Examples of the polyol compound include ester type, adipate type, ether type, lactone type and carbonate type polyol compounds. Examples of ester-type and adipate-type polyol compounds include polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, butenediol, hexanediol, pentanediol, neopentyldiol and pentanediol, adipic acid, sebacic acid and azelaic acid. , A compound obtained by a condensation reaction with a dibasic acid such as terephthalic acid, isophthalic acid, maleic acid, and aromatic carboxylic acid.

Examples of ether type polyol compounds include polyethylene glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol and the like. Furthermore, as the lactone-based polyol compound,
Examples thereof include polycaprolactone glycol, polypropiolactone glycol, polyvalerolactone glycol and the like.

As the carbonate-based polyol compound, a polyalcohol such as ethylene glycol, propylene glycol, butanediol, pentanediol, octanediol, nonanediol, etc. is dealcoholated with diethylene carbonate, dipropylene carbonate, etc. The compound obtained is mentioned. Further, the thermoplastic polyurethane resin may have a linear structure or a partially crosslinked structure. Preferred specific examples of the thermoplastic polyurethane resin used in the method of the present invention include milactolane E-180, E-185, E-19.
0, E-198, P-485 (adipate system), E-3
85 (ether type) (all manufactured by Nippon Miractolan Co., Ltd.), U803 and U803 modified (all manufactured by Nippon Mektron Co., Ltd.). These products are also commonly called thermoplastic polyurethane elastomers.

The thermoplastic polyurethane resin can be supplied to the extruder in any shape, but in general, a so-called pellet shape having a spherical shape, an elliptic shape, a cylindrical shape or the like of about 1 to 5 mm is preferable. The thermoplastic polyurethane resin is melted by heating. This heating and melting are usually performed by an extruder. The extruder used may be either a single-screw (single type, tandem type, etc.) or a twin-screw or more multi-screw extruder, etc., but from the viewpoint of preventing thermal deterioration of the thermoplastic polyurethane, a single-type extruder (L / D =
25-35) is preferable.

The foaming agent usable in the present invention is an easily volatile foaming agent having a boiling point of 20 ° C. or less. Specific examples of the foaming agent include aliphatic hydrocarbons such as n-butane, iso-butane and pentane, 1-chloro-1,1-difluoromethane,
Included are halogenated aliphatic hydrocarbons such as 1,1,1,2-tetrafluoroethane, dimethyl ether (DME), carbon dioxide and the like. These may be used alone or in combination. Of these foaming agents, n-butane and dimethyl ether (DME) are preferred. In addition, since an easily volatile foaming agent having a boiling point higher than 20 ° C. has a weak foaming power,
It is difficult to foam to a desired expansion ratio, and the foaming efficiency is also reduced, so a large amount of foaming agent is required, which is not industrially suitable, which is not preferable. The amount of the foaming agent used is usually 0.5 with respect to 100 parts by weight of the thermoplastic polyurethane resin.
-20 parts by weight, preferably 2-8 parts by weight. 0.5
When the amount is less than or equal to parts by weight, it is not possible to obtain a foamed molded product having a desired ratio, and when the amount is greater than or equal to 20 parts by weight, it is difficult to obtain a good foamed molded product having uniform bubbles due to bumping of the foaming agent from the resin. .

The blowing agent is dispersed in a molten resin containing any of the above additives. The method is not particularly limited, but it needs to be performed under pressure. In particular,
For example, the extruder in which the molten resin is present can be maintained in an airtight state, and a gas or liquid easily volatile foaming agent can be introduced into the extruder, and the operation can be performed under a pressure generated at that time. In the extruder, the above-mentioned molten resin is prepared, and the above-mentioned foaming agent is sufficiently mixed to uniformly disperse the foaming agent in the molten resin.

The additives optionally added to the above-mentioned thermoplastic polyurethane resin include antistatic agents, colorants, bubble control agents, heat deterioration inhibitors, ultraviolet absorbers, and other antioxidants. Lubricants, flame retardants, fillers, antibacterial / antifungal agents and the like can be mentioned. As the antistatic agent, fatty acid alkylolamide, di- (2-hydroxyethyl) alkylamine, polyoxyethylene alkylamine, fatty acid glycerin ester, polyoxyethylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, poly Nonionic surfactants such as oxyethylene alkyl phenyl ether and polyoxyethylene alkyl ether, anionic interfaces such as alkyl sulfonates, alkyl benzene sulfonates, alkyl sulfate ester salts, alkyl ethoxy sulfate ester salts, alkyl phosphate ester acids, etc. Activator, alkyl trimethyl ammonium salt, acyloylamido propyl trimethyl ammonium methosulfate, alkyl benzyl dimethyl ammonium salt, acyl chloride Cationic surfactants such as phosphorus, alkyl betaine type, imidazoline type, amphoteric surfactants alanine type and the like, inorganic salts, polyhydric alcohols, metal compounds, carbon, and the like.

Examples of the colorant include azo, phthalocyanine and perinone dyes, azo, condensed azo, phthalocyanine, anthraquinone, indigo, thioindigo, perinone, perylene, dioxazine and quinacridone. , Isoindolinone type, quinophthalone type,
Pyrrole-based organic pigments, oxides of various metals, sulfides,
Inorganic pigments such as ferrocyanide, chromate, sulfate, carbonate, silicate, carbon, and metal powder can be used.

Examples of the air bubble controlling agent include talc, a surfactant, silicone oil and the like. Examples of the ultraviolet absorber include benzotriazole type, hydroxybenzophenone type, hydroxybenzoate type, phenyl salicylate type, phenyl acrylate type and the like.

These additives are 0.1 to 2 parts by weight of an antistatic agent, 0.1 to 1.0 parts by weight of a colorant, and 0.1 to 1.0 part by weight of a foam control agent to 100 parts by weight of a thermoplastic polyurethane resin.
It is preferable that 1 to 2.0 parts by weight and the ultraviolet absorber are added at a ratio of 0.1 to 1.0 parts by weight. The thermoplastic polyurethane resin may contain these additives in advance, or may be added at the time of heating and melting.

The molten resin mixture obtained as described above is once cooled to a temperature suitable for foaming before being introduced into the die. For example, the melting temperature of the resin is cooled to 200 to 230 ° C. and 130 to 160. Such a molten resin mixture is supplied to the die and further cooled and extruded at the exit of the die. In particular, it is preferable to cool to a temperature suitable for foaming just before the exit of the die. The shape of the die is not particularly limited and is appropriately selected so as to give the desired shape of the foamed molded product.Furthermore, the foamed resin discharged from the die has a desired shape before the resin is completely cooled, For example, it is formed into a rod, tube, sheet, film, board or net. For example, when processed into a sheet, the extruded foam can be processed by a method of passing it between two or more rolls at desired intervals. The roll is preferably cooled in order to lower the temperature of the molded body.

The extruded foamed article obtained by the production method of the present invention has a uniform fineness of 60% or more and a closed cell ratio of 0.0.
The density is 5 to 0.7 g / cc. The polyurethane foam molded article of the present invention has excellent properties such as heat insulation, electrical insulation, mechanical properties, abrasion resistance, and high impact resilience, and is uniform, fine, and has a high closed cell rate. Is. Therefore,
Various sports equipment and daily products (sole, tennis racket,
Skis, sofas, beds, mattresses, cushions, etc., car interior and exterior parts (crash pads, handles, armrests, bumpers, fascias, etc.), packing materials (for rugs, carpets, etc.), heat insulating materials (for vehicles) , For ships, refrigeration equipment, electric refrigerators, showcases, vending machines, heavy oil tanks, pipes, etc.) and the like.

The closed cell ratio is JIS-A-9511.
It is measured according to the method.

[0020]

The method for producing a thermoplastic polyurethane foamed molded article of the present invention comprises heating and melting a thermoplastic polyurethane resin, dispersing an easily volatile foaming agent having a boiling point of 20 ° C. or less in the molten resin under pressure, and It is characterized by being extruded into the air through a die and then foamed, so there is no need to use a conventional pyrolysis type foaming agent, it can be continuously produced in one step, and the obtained foam has a beautiful surface. It is a high expansion ratio having uniform cells with high independence.

[0021]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto. Example 1 Adipate-type thermoplastic polyurethane resin (Miractran E, which was dried in advance at 80 ° C. for 2 hours using a hot air drier.
185, manufactured by Nippon Miractolan Co., Ltd.), and fine powder talc was mixed at a ratio of 1.0 part by weight as a bubble control agent. About 2 to a single screw extruder with a diameter of 65 mm
After supplying at a rate of 0 Kg / cm ^2, the mixture was melt-kneaded at a temperature of 220 ° C.

Then, butane, which is an easily volatile foaming agent, was pressed in at a ratio shown in Table 1, and subsequently kneaded with the resin. Furthermore, after lowering the resin temperature to 150 ° C., it was introduced into the die section connected to the extruder. A rectangular resin outlet having a thickness of 0.9 mm, a width of 100 mm, and a length of 5 mm is installed at the tip of the die portion. The temperature of the die was 95 ° C.

The resin discharged from the resin discharge port was further passed between two cooling rolls to form a sheet having a width of about 180 mm and a thickness of about 5 mm. The obtained sheet-shaped foamed molded article was a good foamed molded article having a uniform and fine closed cell ratio of 76% and a density of 0.25 g / cc. The conditions and results of this example are shown in Table 1. Examples 2 to 8 Example 1 above, except that the conditions are as shown in Table 1.
A foamed molded product was produced by the same method as in. The obtained sheet-shaped foam molded article was a good low-density foam molded article having uniform and fine closed cells.

Detailed results are shown in Table 1. Comparative Examples 1 and 2 Example 1 above except that the conditions were as shown in Table 1.
A foamed molded product was produced by the same method as in. The sheet-like foamed molded product obtained when the decomposable foaming agent was used was a high-density foamed molded product having a poor surface condition and non-uniform cells.

Detailed results are shown in Table 1. Comparative Examples 3 and 4 Example 1 above, except that the conditions were as shown in Table 1.
A foamed molded product was produced by the same method as in. The sheet-shaped foamed molded product obtained by using a resin in which a decomposable foaming agent is kneaded and a resin in which a talc is kneaded is mixed has a high surface density and high density with non-uniform bubbles. It was a foam molded article of

Detailed results are shown in Table 1.

[0027]

[Table 1]

[0028]

EFFECT OF THE INVENTION The thermoplastic polyurethane foam-molded product of the present invention is obtained by heating and melting a thermoplastic polyurethane resin, dispersing an easily volatile foaming agent having a boiling point of 20 ° C. or less in the molten resin under pressure, and subjecting it to die molding. Since it is characterized by being extruded into the air through the foam and then molded, there is no need to use a conventional pyrolysis type foaming agent, the surface is beautiful, and the high expansion ratio with uniform cells with high independence is achieved. The foamed molded product can be produced in one step.

Further, when the easily volatile foaming agent is butane or dimethyl ether, a foamed molded product having highly independent and uniform cells and having a high expansion ratio can be obtained more easily. Further, when the thermoplastic polyurethane foam-molded product has a closed cell ratio of 60% or more, a foam-molded product excellent in heat insulation and elasticity can be obtained.

By using the foaming agent in an amount of 0.5 to 20 parts by weight with respect to 100 parts by weight of the thermoplastic polyurethane resin, it is possible to obtain uniform cells and a desired expansion ratio. Further, the molten mixture is once cooled to a temperature suitable for foaming before being introduced into the die,
It is possible to obtain a foamed molded product having a high surface expansion and a high expansion ratio.

The melt mixture also contains one or more additives such as antistatic agents, colorants, cell regulators, heat degradation inhibitors, and UV absorbers to provide the desired properties. It is possible to obtain a foamed molded article having the same.

[Procedure amendment]

[Submission date] May 19, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The foaming agent usable in the present invention is an easily volatile foaming agent having a boiling point of 20 ° C. or less. Specific examples of the foaming agent include aliphatic hydrocarbons such as n-butane and iso-butane.
Elementary, 1-chloro-1,1-difluoromethane, 1,1,
Included are halogenated aliphatic hydrocarbons such as 1,2-tetrafluoroethane, dimethyl ether (DME), carbon dioxide and the like. These may be used alone or in combination.
Of these foaming agents, n-butane and dimethyl ether (DME) are preferred. In addition, since the easily volatile foaming agent having a boiling point higher than 20 ° C. has a weak foaming power, it is difficult to foam up to a desired foaming ratio, and the foaming efficiency is lowered, so a large amount of foaming agent is required, This is not preferable because it is not industrially suitable. The amount of the foaming agent used is usually 0.5 to 20 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of the thermoplastic polyurethane resin. If the amount is 0.5 parts by weight or less, a foamed molded article having a desired ratio cannot be obtained, and 2
When the amount is 0 parts by weight or more, it is difficult to obtain a good foamed molded product having uniform cells due to the foaming agent bumping from the resin.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

[0027]

[Table 1]

Claims (2)

[Claims] 1. A thermoplastic polyurethane resin is melted by heating, an easily volatile foaming agent having a boiling point of 20 ° C. or less is dispersed in the melted resin under pressure, and this is extruded into the atmosphere through a die to be foam-molded. A method for producing a thermoplastic polyurethane foam-molded article, comprising: 2. The method according to claim 1, wherein the thermoplastic polyurethane foam-molded article has a closed cell ratio of 60% or more.