TWI725502B - TPU foam sole manufacturing process and its finished products - Google Patents

Abstract

A TPU foamed shoe sole manufacturing process, including kneading step, sheeting step, crushing step, drying step and foaming step. The foaming agent is used for kneading, tableting, and pressure release and expansion in the mold, which is different from general use. High-pressure gas is used for foaming to produce TPU foamed shoe soles containing a plurality of air cells, and the air cells include closed cell structure and open cell structure, and the open cell structure accounts for less than 10% of the total cell volume, and the open cell structures are mutually exclusive. Connect with each other.

Description

TPU foam sole manufacturing process and its finished products

The present invention relates to the manufacturing process of foamed shoe soles and the finished products thereof, in particular to those who use TPU elastomers to make them.

Shoes are one of the indispensable daily necessities in human life. It protects the wearer's feet from being directly exposed, stepping on a hot or frozen environment, or moderately protecting the soles of the feet from accidental collision and injury due to external forces. Shoemaking technology With the development of technology and materials, people's choices and requirements for shoes are also increasing, especially for occasions and types of activities to choose shoes with appropriate functions.

From the composition of the shoe, there are roughly two parts: the upper and the sole. The materials used for the sole are rubber, EVA (ethylene vinyl acetate copolymer), PU (polyurethane), and TPE (thermoplastic elastomer). However, the materials selected for the above shoe soles are not perfect. Various materials have their advantages and disadvantages, which also affect the overall price of the shoes. Therefore, when purchasing shoes, consumers must also pay attention to the selection of their materials to facilitate Follow-up maintenance and cleaning. In recent years, the application of TPE (thermoplastic elastomer) to shoe soles is also quite popular, with excellent high elasticity, high strength, and lightweight advantages.

The present invention provides the manufacturing process and finished products of shoe soles made of TPU, but the foaming agent is kneaded, tableted and completed after pressure relief and expansion in the mold, which is different from the general foaming technology using high-pressure gas.

In order to achieve the foregoing objectives and effects, a TPU foamed shoe sole manufacturing process is provided, which includes: a mixing step. The thermoplastic polyurethane elastomer, nucleating agent, slip agent, antioxidant, and ultraviolet absorber are put into the mixing machine, and heated and kneaded. The agglomerated rubber material is prepared by using; in the tableting step, the aforementioned agglomerated rubber material is put into a tablet press and a foaming agent, a chain extender and a strength regulator are added and mixed to obtain a mixed rubber material, and the aforementioned mixed rubber material is further mixed Rolling into flakes, taking out the flakes from the tablet press and cooling to room temperature; in the pulverizing step, passing the aforesaid flakes through a cutting machine and a pulverizing mechanism to obtain 2~5mm pulverized pieces; in the drying step, the aforementioned smashed pieces are crushed The sheet is placed in a drying oven to be dried; in the foaming step, the dried crushed sheet is placed in the sole mold and heated and pressurized, the mold is opened to relieve the pressure to normal pressure and rapidly expand to complete the TPU foamed sole, so that the TPU foams The sole contains multiple air bubbles.

A TPU foamed shoe sole includes a shoe top surface, a shoe bottom surface, and a shoe side surface, the shoe side surface is connected to the shoe top surface and the shoe bottom surface and surrounds a foamed interior, and the foamed interior contains a plurality of air bubbles, And the minimum bubble hole diameter is 0.002mm, and the density of the TPU foam sole is lower than 0.15g/cm ³ , and the hardness of the TPU foam sole is 38~42 Asker C.

Please refer to the first figure. The manufacturing process of the TPU foamed shoe sole of the present invention includes a mixing step, a sheeting step, a crushing step, a drying step, and a foaming step. The following describes the technical features of each step, and please refer to the second to sixth diagrams for cooperation.

In the kneading step, the thermoplastic polyurethane elastomer 10, the nucleating agent 11, the slip agent 12, the antioxidant 13, and the ultraviolet absorber 14 are placed in the kneading machine 21, and a mass compound 31 is obtained by heating and kneading;

In the tableting step, the aforementioned agglomerated rubber material 31 is placed in the tablet press 22 and mixed with the foaming agent 15, the chain extender 16 and the strength modifier 17 to obtain a mixed rubber material 32, and the aforementioned mixed rubber material 32 is further rolled Press and form into a sheet-like body 33, and then take out the sheet-like body 33 from the tablet press 22 and cool it to room temperature;

In the pulverization step, the aforementioned sheet-shaped body 33 is subjected to a cutting machine 23 and a pulverizer 24 to produce a pulverized piece 34 of 2 to 5 mm;

In the drying step, the aforementioned crushed pieces 34 are placed in a drying box 25 to be dried;

In the foaming step, the dried crushed pieces 34 are put into the sole mold 26 and heated and pressurized, and the mold is opened to relieve the pressure to normal pressure and rapidly expand to complete the TPU foam sole 4, so that the TPU foam sole 4 contains plural bubbles.孔41.

In the manufacturing process of the TPU foamed sole of the present invention, the thermoplastic polyurethane elastomer 10, the nucleating agent 11, the slip agent 12, the antioxidant 13, and the ultraviolet absorber 14 are first put into the mixing machine 21, and the speed of the mixing machine 21 is The temperature is 50-60 rpm, the pressure is 6-8 kg/cm ² , and the heating temperature is set to 140° C. to 170° C., so that the raw materials are heated and kneaded in the kneader 21 to obtain a mass 31. Subsequently, the agglomerated rubber material 31 is sent to the tablet press 22, the foaming agent 15, the chain extender 16, and the strength modifier 17 are added, and the rotation speed of the tablet press 22 is 50-60 rpm, and the heating temperature is set to 120 ℃~140℃. Next, it is rolled into a sheet-like body 33 by the tablet press 22, and the thickness of the sheet-like body 33 is 1-2 mm, and is cooled to normal temperature (20-30°C). In addition, the sheet-shaped body 33 that has been cooled down to normal temperature is used with the cutter 23 and the pulverizer 24 to produce 2-5 mm crushed pieces 34. The aforementioned crushed pieces 34 are contained in a container 251 into the drying box 25, and the relative humidity of the drying box 25 is set to be less than 50% and the temperature is 50°C to 70°C, and the crushing pieces 34 are dried. Put the dried crushed pieces 34 into the cavity of the sole mold 26 and close the mold, and set the heating temperature and pressure of the sole mold 26. The temperature of the sole mold 26 is 160°C~180°C, and the pressure of the sole mold 26 It is 100~150 kg/cm ² , so that the crushed piece 34 is melted by heat and undergoes polymerization, chain extension reaction and foaming reaction, and the mold is released to normal pressure and rapidly expands to complete the TPU foamed sole 4, so that the TPU foamed sole 4 It contains a plurality of bubble holes 41, and the plurality of bubble holes 41 includes a closed-cell structure and an open-cell structure, and the open-cell structure accounts for less than 10% of the total volume of the plurality of bubble-holes 41, and the open-cell structures are mutually connected.

The TPU foamed shoe sole 4 produced above includes a shoe top surface 42 and a shoe sole surface 43 and a shoe side surface 44. The shoe side surface 44 is connected to the shoe top surface 42 and the shoe sole surface 43 and surrounds a foamed interior 45, And the foamed interior 45 contains a plurality of bubble holes 41, and the bubble hole 41 has a minimum diameter of 0.002mm, the density of the TPU foamed sole 4 is lower than 0.15g/cm ³ , and the hardness of the TPU foamed sole 4 is 38~42 Asker C The tensile strength of TPU foam sole 4 reaches 25.5Kg/cm ² ; the elongation rate of TPU foam sole 4 reaches 398.72%; the tear strength of TPU foam sole 4 reaches 10Kg/cm; the rebound of TPU foam sole 4 reaches 69%; the thermal shrinkage rate of the TPU foam sole 4 is 0.13%; the withstand peeling of the TPU foam sole 4 reaches 2.9Kg/cm. It is worth mentioning that the TPU foamed sole 4 referred to in the present invention is an example of a shoe midsole.

The aforementioned thermoplastic polyurethane elastomer 10 has a hardness of 35-95 Shore A aromatic, aliphatic, carbonate aliphatic polyether or polyester, and the thermoplastic polyurethane elastomer 10 has a softening temperature of 130°C to 150°C.

The addition amount of the aforementioned thermoplastic polyurethane elastomer 10 is 100 PHR, the addition amount of the blowing agent 15 is 1~6 PHR, the addition amount of the chain extender 16 is 0.5~2 PHR, and the addition amount of the strength modifier 17 is 0.5~2 PHR.

In the aforementioned formula, the polymer auxiliary material 18 is added to the mixed rubber material 32, and the strength and physical properties of the polymer auxiliary material 18 can be increased. The addition amount of the polymer auxiliary material 18 is 2-40 PHR; the aforementioned polymer auxiliary material 18 is selected with a molecular weight of 20,000 to 300,000 Any one or a combination of two or more of polyamide, polyether block amide, maleic anhydride, acrylate, grafted polyolefin, or grafted SEBS. 10-40 PHR of polyether block amide is added to the aforementioned polymer auxiliary material 18 to increase the rigidity and elasticity of the foamed material.

The aforementioned chain extender 16 and strength regulator 17 are aromatic, aliphatic, aliphatic carbonate polyhydroxy functional group or polyisocyanate functional group polymer; slip agent 12 is stearate or amide; nucleating agent 11 is selected two Any one or a combination of two or more of silica, talc, modified calcium carbonate, magnesium silicate or carbon black; the blowing agent 15 is sodium bicarbonate (NaHCO3), 4,4'-oxobisbenzenesulfonate Hydrazine (OBSH), toluenesulfamate (TSS) or dinitrosopentamethyltetramine (DPT).

Please refer to the seventh figure, which is a test comparison between the finished TPU foamed sole and the finished EVA foamed sole. It can be seen that the density of the finished TPU foamed sole of the present invention can be less than that of the finished EVA foamed sole, and it can have a better than EVA foamed sole. The finished product has better tensile strength, elongation, tear strength, rebound, heat shrinkage, compression set rate, and even more resistance to peeling.

10 Thermoplastic polyurethane elastomer 11 Nucleating agent 12 slip agent 13 Antioxidant 14 UV absorber 15 Foaming agent 16 Chain extender 17 Strength modifier 18 Polymer accessories 21 Mixing machine 22 Tablet press 23 Cutting machine 24 Crusher 25 Drying box 251 Container 26 Sole mold 31 agglomerated rubber 32 Mixed rubber 33 Flake 34 Pink Fragments 4 TPU foam sole 41 Bubble hole 42 The top surface of the shoe 43 sole surface 44 Side of the shoe 45 Inside the foam

The first figure is a flowchart of the present invention.

The second figure is a schematic diagram of the mixing, discharging and crushing equipment of the present invention.

The third figure is a schematic diagram of the present invention where the crushed pieces are placed in a drying oven for drying.

The fourth figure is a schematic diagram of the foaming of the present invention.

The fifth figure is a three-dimensional schematic diagram of the TPU foam sole of the present invention.

The sixth figure is an enlarged schematic cross-sectional view of the TPU foamed sole of the present invention.

The seventh figure is a test comparison diagram between the finished TPU foamed sole of the present invention and the finished EVA foamed sole.

Claims (5)

A manufacturing process of TPU foamed shoe soles, which includes: a mixing step, in which thermoplastic polyurethane elastomer, nucleating agent, slip agent, antioxidant, and ultraviolet absorber are put into a mixing machine and heated and kneaded to obtain a mass of rubber; In the step of discharging the tablet, the aforementioned agglomerated rubber material is put into a tablet press and mixed with a foaming agent, a chain extender and a strength regulator to prepare a mixed rubber material, and the aforementioned mixed rubber material is further rolled into a sheet-like body, Take out the flakes from the tablet press and cool to room temperature; in the pulverizing step, pass the aforesaid flakes through a cutting machine and a pulverizing mechanism to obtain smashed pieces of 2 to 5 mm; in the drying step, put the smashed pieces into a drying box to be dried; In the foaming step, the dried crushed pieces are put into the sole mold and heated and pressurized, and the mold is opened to release the pressure to normal pressure and rapidly expand to complete the TPU foamed sole, so that the TPU foamed sole contains a plurality of air bubbles. The TPU foamed shoe sole manufacturing process as described in claim 1, wherein the thermoplastic polyurethane elastomer has an aromatic, aliphatic, aliphatic carbonate polyether or polyester with a hardness of 35-95 Shore A, and the softening temperature of the thermoplastic polyurethane elastomer is 130℃~150℃. The TPU foaming sole manufacturing process as described in claim 1, wherein the addition amount of thermoplastic polyurethane elastomer is 100 PHR, the addition amount of foaming agent is 1~6 PHR, the addition amount of chain extender is 0.5~2 PHR, and the strength regulator is added. The amount is 0.5~2 PHR. The TPU foamed sole manufacturing process as described in claim 1, wherein the chain extender and the strength modifier are aromatic, aliphatic, aliphatic carbonate polyhydroxy functional group or polyisocyanate functional group polymer; the slip agent is stearate or Amides; the nucleating agent is any one or a combination of silicon dioxide, talc, modified calcium carbonate, magnesium silicate or carbon black; the foaming agent is sodium bicarbonate (NaHCO3), 4, 4'-oxobisbenzenesulfonyl hydrazine (OBSH), toluenesulfamate (TSS) or dinitrosopentamethyltetramine (DPT). The TPU foam sole manufacturing process as described in claim 1, wherein the heating temperature of the kneader is 140°C~170°C, the speed of the kneader is 50~60rpm, and the pressure of the kneader is 6~8kg/cm ² ; The heating temperature of the tablet machine is 120℃~140℃, and the speed of the tablet machine is 50~60rpm; the crushed tablets are dried in a drying oven with a relative humidity of less than 50% and a temperature of 50℃~70℃; The temperature is 160℃~180℃, and the pressure of the sole mold is 100~150kg/cm ² .

Images