JPH0436352A - Thermoplastic polyurethane resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition with which low-melting additives can easily be kneaded by mixing an ethylene/vinyl acetate copolymer resin containing additives with a thermoplastic polyurethane resin. CONSTITUTION:51-99wt.% ethylene/vinyl acetate copolymer resin of a vinyl acetate content of 40-80wt.% and an MI of 5-50 at 190 deg.C under a load of 5kg is melt-kneaded with 50-1wt.% additives such as a lubricant (e.g. metallic soap), an antioxidant {e.g. triethylene glycol bis[3-(3-tert.-butyl-5-methyl-4- hydroxyphenyl)propionate]} and a UV absorber [e.g. 2-(5-methyl-2-hydroxyphenyl) benzotriazole] at 30-60 deg.C and extruded into a strand, which is ground to obtain a solid additive composition. This composition is mixed with a thermoplastic polyurethane resin at 180-210 deg.C.

Description

[Detailed description of the invention] [Industrial application field] The present invention focuses on the performance of thermoplastic polyurethane resin.

The present invention relates to a thermoplastic polyurethane resin composition in which additives added to improve functionality can be easily mixed into the resin.

[Prior art and problems to be solved by the invention] Conventionally, the performance of thermoplastic polyurethane resins (for example, moldability,
Various additives have been added to improve the weather resistance, heat resistance, etc. However, when extrusion kneading is used to knead additives into a thermoplastic polyurethane resin, some additives may not be mixed properly, resulting in phenomena such as vent-up, surging, and poor melting. For example, when a lubricant is added to improve the moldability (e.g. mold release, plasticization, etc.) of thermoplastic polyurethane resin, if the melting point of the lubricant is quite low, it may be difficult to The lubricant melts immediately in the cylinder of the extruder, causing the above-mentioned defective extrusion phenomenon and making it impossible to mix wires. Furthermore, when blending a solid lubricant concentrate (so-called lubricant master pellets) into which a lubricant has been added at a high concentration into a thermoplastic polyurethane resin, it is difficult to melt and knead at low temperatures when a normal thermoplastic polyurethane resin is used as the base resin. It was not possible to obtain a concentrated master pellet.

In other words, when preparing lubricant master pellets to which a lubricant with a relatively low melting point is added at a high concentration, using a thermoplastic polyurethane resin as the base resin has the problem that melt-kneading cannot be performed well.

The object of the present invention is to create a solid material containing a relatively low melting point additive that is difficult to add to thermoplastic polyurethane resin, such as a low melting point lubricant for poor moldability. To provide a thermoplastic polyurethane resin composition in which an additive composition is easily and stably produced using an ordinary I-screw extruder, and the additive composition is added and mixed with a thermoplastic polyurethane resin.

[Means for solving problems]

The present inventors have completed the present invention as a result of intensive research to solve the above problems.

That is, the present invention relates to a thermoplastic polyurethane resin composition prepared by adding and mixing an additive composition comprising an additive and an ethylene-vinyl acetate copolymer resin to a thermoplastic polyurethane resin.

As the base resin for a high concentration additive composition (hereinafter referred to as additive master pellets), it is preferable to use a thermoplastic resin with a low melting point (softening point) so that even relatively low melting point additives can be sufficiently mixed. As can be seen, for the thermoplastic polyurethane resin that is the object of the present invention, temperatures ranging from room temperature to 80°C
An ethylene-vinyl acetate copolymer resin that can be extruded is preferred.

It is preferable that the resin has a solid shape in order to add the additive at a high concentration. Furthermore, the vinyl acetate content in this ethylene-vinyl acetate copolymer resin is preferably in the range of 40 to 80% by weight, and the melt index (190°C,
5 kg load) is preferably in the range of 5 to 50.

On the other hand, any additive (having a melting point of approximately 160° C. or lower) that is difficult to knead into the thermoplastic polyurethane resin as it is due to its low melting point can be used.

Typical examples of such additives include lubricants used to improve moldability such as mold releasability and plasticizing ability, such as metal soaps (-p
:148-155℃), aliphatic amide type (*p:141
~146℃), MDI-stearyl alcohol type (+m
p: around 12B℃), hydrocarbon type (+np: 11B~1
28°C), ester type (Ilp=98-104°c)
, montanic acid ester type (mp: around 80°C), fatty acid type (mp: around 70°C), fatty acid alcohol type (#lP = around 60°C), etc.; Antioxidants such as hindered phenol triethylene glycol-bis [
3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate) (wp near 5-79°C),
Pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) (+wp: 110-125°C), 2.2thiobis(4-methyl-6-1-butylphenol) ( llp
2-(5-methyl-2-hydroxyphenyl)benzotriazole (+np: 12B to 132°C), etc.
), 2-(3,5-di-t-amy-2-hydroxyphenyl)benzotriazole (mp: 280°C)
etc.; hydrolysis inhibitors such as carbodiimide, 4-t
- Butylcatechol type, fatty acid amide type, etc., fungicidal agents such as pentachlorophenol, pentachlorophenol laurate, copper-8-hydroxyaniline, etc. Flame retardants such as bromine-phosphorus compounds, organic bromine compounds, chloroalkyl phosphates, etc., and antistatic agents. agent (various surfactants)
can be mentioned.

Among these additives, it is particularly effective to use additives with a melting point of 120'C or less, which do not easily form a solid state near the flow start point (approximately 90 to 100C) of the thermoplastic polyurethane resin. Optimally, the additive has a melting point below 100°C.

The content of the additive in the master pellet is preferably 1 to 50% by weight. If the content of the additive exceeds 50% by weight, it is not preferable because it becomes difficult to collect the extruded master pellets or makes extrusion kneading impossible.

In addition, the additive master pellets are manufactured using a single screw extruder,
This can be carried out using equipment capable of melting and mixing, such as a axial extruder, Banbury mixer, two-roll machine, or Brabender Plastograph, but single-screw extruders (full-flight screw type ) is valid. An example of an actual manufacturing method is shown below. Ethylene-vinyl acetate copolymer resin (solid) 51-99% by weight, additive 1
~50% by weight is mixed using a mixer such as a Henschel mixer. At this time, it goes without saying that the additive may be a single-component system, such as a lubricant alone, or a multi-component system, such as a lubricant and other additives (such as a hydrolysis inhibitor). The mixture is then charged into the hopper of a single screw extruder. The barrel and die temperature of the extruder is 30 to 40°C on the hopper side, 40 to 50°C on the center, 100°C on the tip (
Die) 50 to 60°C is preferable. If the melting point of the lubricant and other additives is low, around 80 to 120°C, raising the temperature of each zone of the extruder higher than this will cause the lubricant and other additives to melt, making it difficult to mix them well with the base resin in the extruder. is not possible, and defects such as vent-up occur.

However, the granular ethylene-vinyl acetate copolymer resin used in the present invention has a softening point of 90"C or less and a softening point of 40 to
Since it can be extruded at a temperature of 60°C, there is no such concern at all. In this way, in the present invention, in order to knead low melting point additives, which were conventionally difficult to add, into the base resin in a solid state below the melting point, a master that is stably blended at a high concentration ratio is used. The feature is that pellets can be obtained.

Furthermore, the present invention has the advantage that it can be applied to additives with a fairly low melting point of 60 to 80''C, so it can be applied to a very wide range of additives.

The additive master pellets produced in this way are
Can be concentrated up to 100 times the final content, with a thermoplastic polyurethane resin:additive master pellet ratio of 10
It is now possible to mix at an extremely high dilution ratio of 0:1. Therefore, the final content of the ethylene-vinyl acetate copolymer resin in the base resin in the thermoplastic polyurethane resin is 0.5% by weight or less, and there is no problem with the influence on the moldability, physical properties, etc. of the thermoplastic polyurethane resin. . By blending the additive master pellets thus obtained with a thermoplastic polyurethane resin and molding at a molding temperature of 180 to 210'C, it has become possible to mold a thermoplastic polyurethane resin composition that improves moldability and the like.

〔Example〕

The present invention will be explained below by giving examples.

Example 1 Particles of ethylene-vinyl acetate copolymer resin (manufactured by Dainippon Ink & Chemicals, Evasuren HP-30) 50% by weight
, Montanic acid ester wax lubricant (melting point 79-85
A mixture consisting of 20% by weight of a polycarbodiimide-based hydrolysis inhibitor (melting point: about 80°C, powdery) and 30% by weight of a polycarbodiimide-based hydrolysis inhibitor (melting point: about 80°C, powdery) was mixed by stirring.

The obtained mixture was extruded into a strand using a 50 mm diameter single screw extruder (full flight screw type) at a barrel temperature of 40 to 60 °C below the melting point of the additive and a die temperature of 50 to 60 °C, and cooled with water. Pellets were made using a pelletizer. The obtained master pellets were mixed with a polyester thermoplastic polyurethane resin (manufactured by Dainippon Ink & Chemicals, Bandex hardness JIS 908) at a ratio of 100:1 (
(weight ratio) and used at a molding temperature of 180-210°C. The lubricant was well dispersed in the thermoplastic polyurethane resin, and a thermoplastic polyurethane resin having excellent mold release properties and blooming resistance was obtained.

Example 2 A blend consisting of 50% by weight of the ethylene-vinyl acetate copolymer resin particles used in Example 1 and 50% by weight of the montanic acid ester wax lubricant was stirred and mixed. The obtained mixture was heated to a barrel temperature of 40 to 60° below the melting point of the lubricant using a 3 Ononφ single screw extruder (full flight screw).
C, extruded into a strand at a die temperature of 50-60°C,
Pelleted.

The obtained master pellets were mixed with a polyester thermoplastic polyurethane resin at a blending ratio of 50:1.
Extruded at 80-210°C. The extrusion kneading was successful and thermoplastic polyurethane resin pellets with excellent mold release properties were obtained.

Example 3 Master pellets were obtained in the same manner as in Example 2, except that a polycarbodiimide hydrolysis inhibitor was used in place of the montanic acid ester wax lubricant.

The obtained master pellets were mixed with a polyester thermoplastic polyurethane resin and extruded.

Extrusion kneading was good and the appearance of the pellets was uniform.

Comparative Example 1 Lactone-based thermoplastic polyurethane resin powder (hardness J
Using 100 parts by weight of IS 80A) as the base resin, the temperature was 170°C at 930r using a Brabender plastograph.
In p+, 3 parts by weight of a montanic acid ester lubricant and 4.5 parts by weight of a polycarbodiimide hydrolysis inhibitor were mixed and kneaded. Due to melting of the lubricant, crosstalk was insufficient and a uniform melt could not be obtained.

Comparative Example 2 3 parts by weight of a lubricant and 4.5 parts by weight of a hydrolysis inhibitor were blended in the same manner as in Comparative Example 1 to 100 parts by weight of adipate thermoplastic polyurethane resin pellets (hardness JIS 95A), and the mixture was extruded using a twin-screw extruder. (L/D=34.Rotating in the same direction) was used for extrusion. The melt was not completely melted and defective phenomena such as surging occurred, making it impossible to obtain good master pellets.

Comparative Example 3 2 parts by weight of a montanic acid ester lubricant and 3 parts by weight of a polycarbodiimide hydrolysis inhibitor were mixed with 100 parts by weight of an adipate thermoplastic polyurethane resin powder (hardness JIS 95A), Attempts were made to extrude and pelletize using a full-flight screw extruder at a barrel temperature of 200°C and a goose temperature of 195°C, but the thermoplastic polyurethane resin slipped due to the melting of the lubricant, resulting in poor mixing.

Comparative Example 4 100 parts by weight of adipate thermoplastic polyurethane resin pellets (flow starting point 90 to 100°C), 3 parts by weight of a montanic acid ester lubricant, and 4.5 parts by weight of a polycarbodiimide hydrolysis inhibitor were blended to create Flabender. Although kneading was carried out using a blastograph at a temperature of 120''C and 30 rpm, the thermoplastic polyurethane adhered to the metal surface and the wiring work was extremely difficult.

The results are summarized in Table 1 below.

／ ／ ／ ／ ／ [Effects of the Invention] The present invention provides a thermoplastic polyurethane resin composition in which additives that were conventionally difficult to knead into thermoplastic polyurethane resin, that is, additives with low melting points, can be easily kneaded. It is a thing.

Claims (1)

[Scope of Claims] 1. A thermoplastic polyurethane resin composition characterized in that an additive composition comprising an additive and an ethylene-vinyl acetate copolymer resin is added and mixed with a thermoplastic polyurethane resin. 2. The thermoplastic polyurethane resin composition according to claim 1, wherein the ethylene-vinyl acetate copolymer resin is in a solid state. 3. Ethylene-vinyl acetate copolymer resin is 40 to 80
Contains % vinyl acetate by weight and has a melt index (1
Claim 1: 90°C, 5kg load) is in the range of 5 to 50.
and the thermoplastic polyurethane resin composition according to 2.