JP3976576B2 - Thermoplastic polyurethane composition - Google Patents

Description

【００３３】
各実施例について、再成形可能回数を確認したところ、少なくとも再生3回程度までは耐熱性および圧縮永久歪の低下がみられないという結果が得られた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermoplastic polyurethane composition. More specifically, the present invention relates to a thermoplastic polyurethane composition having excellent compression set characteristics.
[0002]
[Prior art]
Thermoplastic polyurethane has excellent properties such as mechanical properties, abrasion resistance, elastic recovery, oil resistance, and flexibility, and can be melt-molded. As a substitute for conventional synthetic rubber and plastic, It is used in a wide range of applications such as packing, automobile parts, hoses, belts, bearings, sealing materials. Furthermore, recently, due to the expansion of usage applications, improvement of heat resistance and compression set characteristics as a material is required.
[0003]
However, because the heat resistance and mechanical properties of thermoplastic polyurethane depend on physical constraints such as hydrogen bonding of the hard segment part contained in the polymer chain, the influence of the soft melting point and thermal stability of the hard segment is strong. In the past, it was not always satisfactory. One way to improve the heat resistance and compression set properties is to increase the hard segment content. In this case, the melt viscosity during molding increases, for example, in a mold. The appearance defect of the molded product due to the flow spots of the resin occurs, and the moldability deteriorates. Moreover, there existed a problem that the hardness of a molded object raised and a softness | flexibility fell.
[0004]
On the contrary, as a method for improving the moldability by reducing the melt viscosity at the time of molding, there is a means of reducing the ratio of the hard segment in the reaction raw material, that is, the ratio of the chain extender and the corresponding diisocyanate component to the whole. However, this method deteriorates mechanical properties, heat resistance, and compression set properties.
[0005]
Thus, it is difficult to satisfy mechanical characteristics, heat resistance, and compression set characteristics due to the hard / soft ratio of the raw material urethane.
[0006]
In order to solve these problems in terms of blending and molding, methods such as adding a plasticizer and raising the molding temperature have been proposed. The actual situation is that there are many problems such as bleed and other changes in physical properties over time, heat resistance decreases, mold temperature contamination increases when the molding temperature is raised, and thermoplastic polyurethane deteriorates. .
[0007]
As a method for improving the heat resistance and dimensional stability of thermoplastic elastomers and rubber materials, Japanese Patent Application Laid-Open No. 60-173057 shows the addition of a reactive phenol resin, but it requires treatment at high temperature for a long time. The melting type has a problem that it melts at the time of molding. Also, the compression set characteristics are not improved so much with resin powder. Furthermore, JP-A-47-4179 proposes a material in which granular rubber is blended with a urethane material. However, once this material is molded, there is a disadvantage that it cannot be re-molded, and the object is heat. There is a problem that a long time is required for molding with a curable (casting) material and it cannot be applied to an injection material.
[0008]
In thermoplastic polyurethane, it is difficult to achieve compatibility between various properties such as moldability and mechanical properties, heat resistance, and compression set properties, and this is an important problem.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide a thermoplastic polyurethane composition having improved compression set characteristics and heat resistance without impairing moldability and mechanical characteristics.
[0010]
[Means for Solving the Problems]
An object of the present invention is to use a silicone rubber elastic powder or acrylic rubber elastic powder having a particle size of 5 to 500 μm and a decomposition point of 200 ° C. or higher as a thermoplastic polyurethane, a polyol component used for the polyurethane reaction, It is achieved by a chain extender and a total weight thermoplastic polyurethane composition prepared by adding 5 to 80 parts by weight per 100 parts by weight of diisocyanate.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Thermoplastic polyurethane (polyurethane-based thermoplastic elastomer) is a diisocyanate polyaddition reaction product of a long-chain glycol having a terminal active hydrogen and a short-chain glycol (chain extender), a hard phase having a urethane structure, polyester, and polyether. It has a block polymer structure with a soft phase and the like, and can be produced by any one of the one-shot method and the prepolymer method.
[0012]
As the long-chain glycol having a terminal active hydrogen (polyol component), a polyester polyol, a polyether polyol, an acrylic polyol, a silicone polyol, a 1,4-polybutadiene polyol having a molecular weight of about 500 to 6000, preferably about 1000 to 3000, 1 , 2-polybutadiene polyol, phenolic polyol, flame retardant polyol, castor oil polyol, and the like are used. Polyester polyols are condensation reactions of dicarboxylic acids such as adipic acid, isophthalic acid, and terephthalic acid with polyols such as ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexanediol, trimethylolpropane, and neopentyl glycol. Products, polycaprolactone polyols, polycarbonate polyols, etc., and as polyether polyols, polypropylene glycol polyols or their ethylene oxide-modified products, amine-modified products, polyoxytetramethylene glycol, etc. are used. These polyol components are used in a proportion of about 30 to 90% by weight, preferably about 40 to 70% by weight, in the urethanized raw material. If the ratio is less than this, the moldability deteriorates. On the other hand, if the ratio is greater than this, the compression set characteristics deteriorate.
[0013]
Examples of other reaction components, which are short-chain glycols (chain extenders) include 1,4-butanediol, 1,6-hexanediol, 2,3-butanediol, p-phenylenedi (β-hydroxyethyl), ) Glyceres such as ether, p-xylylene glycol, glycerin monoallyl ether, dimethylol dihydropyran, diamines such as ethylenediamine, 3,3′-dichloro-4,4′-diaminodiphenylmethane, diethyltoluylenediamine, water, etc. One or more of them are used in an amount of about 1 to 60% by weight, preferably about 5 to 40% by weight. If it is used in a proportion higher than this, the moldability deteriorates, whereas if it is used in a proportion lower than this, the heat resistance and compression set properties deteriorate.
[0014]
Examples of diisocyanates that react with these polyol components and chain extenders include aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, Hydrogenated 4,4'-diphenylmethane diisocyanate and other alicyclic diisocyanates or xylylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, tolidine diisocyanate, p-phenylene diisocyanate, 1,5-naphthylene diisocyanate, etc. One or more aromatic diisocyanates are used in an amount of about 5 to 70% by weight, preferably about 15 to 40% by weight. If it is used in a proportion higher than this, the moldability deteriorates, whereas if it is used in a proportion lower than this, the heat resistance and compression set properties deteriorate.
[0015]
In the polyurethane reaction using the above components, a tin compound, an amine compound or the like can be added and used as a catalyst as necessary.
[0016]
When the polyurethane-forming reaction is performed by the one-shot method, rubber elastic body powder is added to each component of the reaction, and when the polyurethane-forming reaction is performed by the prepolymer method, the rubber elastic body powder is added. As the rubber elastic powder, those having a particle size of about 5 to 500 μm, preferably about 5 to 300 μm and having a decomposition point of 200 ° C. or more are used. If a material having a decomposition point lower than this is used, the heat resistance and compression set properties are inferior.
[0017]
As the rubber elastic body powder , silicone rubber or acrylic rubber that has rubber elasticity by crosslinking is used. The rubber elastic body has a reactive group inside or is subjected to surface treatment. It may be. As the rubber elastic powder, burrs of rubber products and pulverized products of recycled rubber can be used.
[0018]
These rubber elastic body powders are used in a proportion of about 5 to 80 parts by weight, preferably about 10 to 40 parts by weight, based on 100 parts by weight of the total amount of polyol component, chain extender and diisocyanate used in the polyurethane reaction. . If the addition ratio is less than this, the heat resistance and compression set properties are not improved, whereas if it is used at a higher ratio, the mechanical strength such as strength and elongation is lowered. .
[0019]
In the composition containing the above components as essential components, a filler, metal oxide, metal hydroxide, lubricant, antioxidant and the like are further blended as necessary.
[0020]
The obtained rubber polyurethane powder-containing thermoplastic polyurethane is molded into a sheet using an injection molding machine, extruder, casting method, etc., and then annealed at about 80-150 ° C. for about 5-24 hours. Secondarily crosslinked.
[0021]
【The invention's effect】
The thermoplastic polyurethane-containing thermoplastic polyurethane according to the present invention improves the compression set characteristics and heat resistance without deteriorating the moldability and mechanical characteristics inherent in the thermoplastic polyurethane. Moreover, since re-molding is possible, it is excellent in reusing and recyclability of the molding burr. Such an effect is an effect inherently found in the thermoplastic polyurethane elastomer and cannot be seen in the cast polyurethane elastomer.
[0022]
【Example】
Next, the present invention will be described with reference to examples.
[0023]
Example 1
After 400 g of polycaprolactone diol (molecular weight: about 2000, OH number: 56.1) was melted at 110 ° C., it was dried under reduced pressure at this temperature for 45 minutes and charged into a reactor preheated to 120 ° C. Then, 211 g of tolidine diisocyanate was added with stirring and reacted for 30 minutes, and the prepolymer formed therein was stirred with dimethyl silicone rubber elastic powder (Toray Dow Corning Silicone Product Trefil E600; particle size 5 μm, decomposition point; (450 ° C.) 99 g (15 parts by weight per 100 parts by weight of polyurethane) was added, and the mixture was further stirred for 60 seconds.
[0024]
Thereafter, the reaction product was poured from a reaction vessel onto a hot plate, cured, placed in an oven preheated to 100 ° C., allowed to stand for 15 hours, and cooled to obtain a rubber polyurethane powder-containing thermoplastic polyurethane composition. After pulverizing this, it was molded into a sheet (150 × 150 × 2 mm) using an injection molding machine under the molding conditions of a nozzle part of 230 ° C. and a cylinder part of 180 ° C., and oven-crosslinked at 125 ° C. for 12 hours.
[0025]
Example 2
In Example 1, 400 g of polycarbonate diol (molecular weight: about 2000, OH number: 56.1) was used instead of polylactone diol.
[0026]
Example 3
In Example 1, 99 g of acrylic rubber elastic body powder (Sekisui Chemicals product ACR-15; particle size 15 μm, decomposition point: 250 ° C.) was used as the rubber elastic body powder.
[0027]
Example 4
In Example 1, 99 g of acrylic rubber elastic body powder (Sekisui Plastics product ACR-30; particle size 30 μm, decomposition point: 250 ° C.) was used as the rubber elastic body powder.
[0028]
Comparative Example 1
In Example 1, dimethyl silicone rubber elastic powder was not used.
[0029]
Comparative Example 2
In Example 2, dimethyl silicone rubber elastic powder was not used.
[0030]
Comparative Example 3
In Example 1, 99 g of dimethyl silicone resin powder (Toray Dow Corning silicone product Tospearl 145; particle size 5 μm, decomposition point: 450 ° C.) was used instead of dimethyl silicone rubber elastic powder.
[0031]
Comparative Example 4
In Example 1, instead of dimethyl silicone rubber elastic powder, ethylene-acrylic copolymer rubber elastic powder having a softening point of 200 ° C. or lower (Sumitomo Seikagaku product flow beads EA209; particle size 25 μm, softening point: 100 ° C.) 99g was used.
[0032]
About the sheet | seat obtained by the above each Example and comparative example, the following each item was measured and the obtained result was shown to the following table | surface.
Normal physical properties: ASTM D-412-83 compliant compression set: 75% Compression viscosity: Toyo Seiki Capillograph used, Extrusion speed: 10mm / min Moldability: Evaluated good flowability

[0033]
For each example, the number of remoldable times was confirmed. As a result, the heat resistance and the compression set were not reduced until at least about 3 times of regeneration.

Claims (1)

Silicone rubber elastic powder or acrylic rubber elastic powder having a particle size of 5 to 500 μm and a decomposition point of 200 ° C. or higher is added to thermoplastic polyurethane, and the total of polyol component, chain extender and diisocyanate used in the polyurethane reaction thermoplastic polyurethane composition prepared by adding 5 to 80 parts by weight relative to the amount 100 parts by weight.