Injection molding

TPE elastomer soft gel can be adjusted to appropriate hardness according to product property requirements (hardness range Shore 25-90A),

Transparent TPE material, due to its high light transmittance, requires strict surface quality of material products, without any defects such as streaks, pores, whitening, halos, black spots, discoloration, poor gloss, etc. Therefore, throughout the injection molding process, strict and even special attention must be paid to TPE raw materials, equipment, molds, and even product design.

Styrenic transparent TPE is widely used in the footwear industry, largely replacing rubber; at the same time, its applications in industrial rubber products such as rubber sheets and plates are also expanding.

TPE overmolding injection bonding generally adopts the two-shot injection molding process, which fixes the injection molded hard plastic part on the overmold,

TPE is a classic aggregation-induced emission molecule, meaning it has no fluorescence in solution but strong fluorescence in solid state. Therefore, transparent TPE materials also have important applications in organic optoelectronics and other fields.

Transparent TPE, specifically is a thermoplastic elastomer, while TPR is translated from English, strictly speaking it is called thermoplastic rubber. This is the most basic difference. TPE is generally modified from SEBS base material, while TPR is modified from SBS base material.

TPE material has good fluidity and is mainly injection molded.

The thickness of the TPE/TPR overmolding layer. In most overmolding applications, a wall thickness range of 1.5-3.0mm will ensure good adhesion. If the TPE layer is too thin, injection molding is difficult, adhesion strength is low, and the feel is poor. If the TPE layer is too thick, on the one hand, the cost is high, and on the other hand, defects such as shrinkage and bubbles are prone to occur.

To achieve the matte appearance of thermoset rubber, a rougher mold surface is required. Generally speaking, the rough surface produced after electrical discharge machining (EDM) of the mold cavity will produce an excellent workpiece appearance and make demolding relatively easy. Abrasive methods such as steam blasting, sandblasting, or shot blasting, as well as chemical etching, can also be used to produce surfaces with different gloss and appearance.

1. Effect of temperature

Different TPE materials have different sensitivities to temperature. For example, when measuring the melt flow index, you can test at several temperatures. If the melt flow index varies greatly, it indicates that the viscosity of the TPE material is highly sensitive to temperature, making it suitable for extrusion materials.

2. Effect of low molecular weight additives

Low molecular weight additives can reduce the interaction force between macromolecular chains, thereby reducing viscosity and making it easier to fill the mold. This is easy to explain: small molecule additives can be understood as added mineral oil.

3. Effect of molecular weight

The same TPE material can have different molecules and molecular weight distributions. The larger the molecular weight, the stronger the intermolecular force, and the higher the viscosity. When the molecular weight is the same, a narrower molecular weight distribution often results in lower viscosity. For example, TPE base material YH503T has higher viscosity than YH502.

4. Effect of shear rate

Effectively increasing the shear rate of plastic can reduce the melt viscosity, but different plastics are affected differently by shear rate. When measuring the melt flow index, you can test at several pressures. If the melt flow index varies greatly, it indicates that the material viscosity is highly sensitive to shear, making it suitable for injection molding materials.

5. Effect of pressure

Although high injection pressure can increase injection speed and achieve high shear during the injection process, which seems beneficial for reducing viscosity, from a physical perspective, increasing pressure actually increases the melt viscosity. The reason is simple: there is already excess space between macromolecular chains due to intermolecular forces. Increased pressure reduces the distance between molecules, making the movement of molecular chains more difficult, thus increasing the overall flow viscosity.

1. From the material perspective:

1. Reduce the oil filling degree of the material;

2. Increase the filler percentage of the material;

3. Find suitable polypropylene and other plastic continuous phases.

2. From the TPE injection molding process:

1. Reduce the injection temperature;

2. Reduce the mold cooling temperature;

3. Increase the injection pressure;

4. After demolding, place the product directly in cooling water.

In fact, the Chinese name of TPE is thermoplastic elastomer, also known as thermoplastic rubber. It is a material that can be directly processed and molded without vulcanization, and has rubber elasticity. Currently, domestic TPE manufacturers are mainly divided into styrene-based thermoplastic elastomer SBS, thermoplastic polyurethane TPU, thermoplastic polyolefin elastomer TPO, polyester elastomer TPEE, etc. Next, let's take a look at the differences between these types!

1. Thermoplastic polyester elastomer TPEE
TPEE (thermoplastic polyester elastomer) is a block copolymer containing polyester hard segments and polyether soft segments. TPEE has the elasticity of rubber and the strength of engineering plastics; the soft segments give it elasticity, making it like rubber, and the hard segments give it processability, making it like plastic. Compared with rubber, it has better processing performance and longer service life; compared with engineering materials, it also has high strength, but better flexibility and dynamic mechanical properties. TPEE can withstand low and high temperatures, and can be used for a long time under conditions of -40 to 160°C. TPE has excellent chemical resistance, weather resistance and aging resistance. It is mainly used where shock absorption, impact resistance, flex resistance, sealing and elasticity, oil resistance, chemical resistance and sufficient strength are required. Such as: polymer modification, automotive parts, high and low temperature resistant wire sheaths, hydraulic hoses, shoe materials, transmission belts, rotomolded tires, flexible couplings, sound absorption, elevator slides, anti-corrosion, wear-resistant, high and low temperature resistant materials, etc.

2. TPU

TPU is made by blending polypropylene PP and ethylene propylene diene monomer rubber (EPDM). During the blending process, EPDM rubber is distributed as a dispersed phase in the PP continuous phase. At the same time, during the blending of PP and EPDM, EPDM itself begins to vulcanize, and this process is called dynamic vulcanization. The self-vulcanization of EPDM does not affect the injection molding of TPV because EPDM exists as a dispersed phase; on the contrary, the presence of vulcanized cross-linked EPDM enhances the wear resistance, strength, and acid/alkali corrosion resistance of TPV, etc.

3. SBS

SBS includes styrene-butadiene block copolymer SBS and its hydrogenated polymer SEBS, as well as modified materials of SBS and SEBS: TPS and TPES (Some in the elastomer industry call TPS TPR, and TPES is also called TPE in the elastomer industry, which is different from the general scope of TPE materials). SEBS and SBS elastomers are mostly used for polymer material modification, toughening, and tackifying resins for adhesives, coatings, and inks, while SEBS and SBS modified materials, TPES, TPS, etc. have more flexible and diverse physical properties and hardness, and are therefore widely used in toys, daily necessities, sports and fitness products, automotive supplies, medical devices, shoe materials, wire and cable industries. Because of this, the consumption of styrene-based thermoplastic elastomers is the largest among all TPEs worldwide.

4. TPO

TPO is composed of rubber and polyolefin. Usually, the rubber component is ethylene propylene diene monomer (EPDM), nitrile butadiene rubber (NBR), and butyl rubber; the polyolefin component is mainly polypropylene (PP) and polyethylene (PE). TPO has become the main rubber-plastic material for automobiles and home appliances, with automotive consumption accounting for more than 75% of total output. It is the fastest-growing variety of TPE.

TPE overmolding typically uses a two-shot injection molding process.

Transparent TPE is used in appliance housings, handles, grips, etc. It offers excellent tactile feel, non-slip and labor-saving properties, and is easy to color and process, with a wide design space.

Diene-based transparent TPE, diene-based TPE is mainly an isomer of natural rubber, so it is also called thermoplastic trans-natural rubber. Although its heat resistance and mechanical strength are not as good as rubber, it is widely used in shoemaking, sponge, optical film, and other industrial rubber products due to its good transparency, weather resistance, electrical insulation, and photodegradability.

TPE is used in overmolding, with the soft TPE as the outer soft layer.

Transparent TPE is used in stationery, sports equipment, etc. It has good UV resistance, chemical resistance, and is easy to color and process.

Transparent TPE, specifically is a thermoplastic elastomer, while TPR is translated from English, strictly speaking called thermoplastic rubber, which is the most basic difference. TPE is generally modified from SEBS base material, while TPR is modified from SBS base material.

During the molding process of TPE material, during the filling of the mold cavity.

Transparent TPE is used in appliance housings, handles, grips, etc. It offers excellent tactile feel, non-slip and labor-saving properties, and is easy to color and process, with a wide design space.

TPE high-transparency material has different product properties in different applications. Thermoplastic elastomer, also known as TPE material, transparent TPE not only has the processing properties of thermoplastic plastics but also the physical properties of vulcanized rubber. This is the so-called advantageous combination of plastics and rubber. Transparent TPE is widely used in people's daily life and production.

With the increasingly widespread application of TPE materials, many related enterprises have emerged and established themselves both domestically and internationally in recent years. However, many people do not have a good understanding of the hardness of TPE and do not know how to control it, which has caused a lot of trouble. So, how to control the hardness of TPE? Last time, I shared the shrinkage rate of TPE. Now, the technical staff of Zhongsuwang will share with you how to control the hardness of TPE.

How to control the hardness of TPE:

1. For general TPE, hardness adjustment is done by the content of oil, PP, and calcium carbonate. Increasing the amount of PP or calcium carbonate increases the hardness, and vice versa. Adding oil reduces the hardness.

2. If the oil filling is normal but there is still oil leakage and stickiness, it indicates that the quality of the SEBS/SBS material or the oil is poor. Among all SEBS materials, Kraton has the best oil filling effect, sometimes able to fill up to 10 times its weight.

3. Oil-filled SBS/SEBS tend to turn yellow, mainly because naphthenic oil contains unsaturated double bonds that oxidize and turn yellow. Usually, domestic Karamay naphthenic oil is hydrogenated and will not cause this problem, so be careful when selecting oil.

4. Often, our products have parameters such as hardness, tensile strength, etc. Oil can only reduce hardness and tensile strength, so engineering plastics are usually added as well, such as PP is often added when making TPE. Parameters like hardness and strength can be adjusted according to the amount of PP and oil filling.

5. When filling oil, try to keep stirring or turning. If left to stand, it is easy for TPE/TPR to clump and the oil filling will be uneven. When the oil filling amount is high, the rotation speed should be reduced, as high speed can easily cause the oil already filled in SEBS/SBS to leak out (the principle is similar to that of a washing machine's spin cycle). After oil filling, it is best to let it sit for a while so that the oil is fully absorbed by the SEBS/SBS before production, otherwise, oil leakage may easily occur during production.

With the rapid development of TPE materials, the demand for TPE thermoplastic elastomers is also increasing. However, when some businesses learn about TPE thermoplastic elastomers, they find that TPE thermoplastic elastomers shrink. So why does TPE thermoplastic elastomer shrink? Will its shrinkage have any impact on product processing? Below, Zhongsuwang professionals will solve these problems for you. We hope that after reading, businesses who do not understand can gain a better understanding of TPE materials.

1. When the state of TPE begins to change from molten to cooling, its molecules align with each other, causing the overall dimensions of the molded part to shrink. Although this shrinkage is generally in the range of a few thousandths of an inch, it is enough to significantly affect the molding and demolding of the part, as well as the final appearance of the finished product. If the shrinkage is uneven, it can cause an originally flat part to become warped or deformed. Therefore, when producing TPE, tolerance requirements are relatively strict. For these reasons, shrinkage is usually taken into account during the production of TPE.

2. TPE (TPR) materials based on SBS have good water resistance. Generally, the shrinkage rate of TPE/TPR materials is about 1.5~3%. However, TPU based on polar materials such as polyester or polyether is not water-resistant, but it generally swells when exposed to water rather than shrinks, and the usage conditions are also not certain. Because different formulas have different physical properties, the shrinkage rates produced vary. Each TPE manufacturer has a different shrinkage rate.

3. Molding conditions can significantly affect the degree and nature of shrinkage. If the state changes rapidly from high stress to low stress, the degree of shrinkage will increase. Rapid cooling of the part and high injection speed or pressure can also affect shrinkage.

4. When producing TPE, considering shrinkage from the design aspect, the mold must be machined slightly larger than the required dimensions of the part. The actual shrinkage value can only be known when the specific part is molded. Therefore, it is always best to be conservative beforehand. Some TPEs are more anisotropic than others, meaning they may shrink more in one direction than in another. This factor must be taken into account when designing the mold.

Finally, we obtain that the shrinkage rate of TPE materials is 1.5~3%, which is normal. Moreover, because during the production of TPE, manufacturers usually take the shrinkage of TPE materials into account, its shrinkage will not have any impact on product processing. Therefore, you can rest assured when purchasing.

TPE uses overmolding injection processing, common products such as handles, grips, electronic materials, etc.

Transparent TPE, specifically speaking, is a thermoplastic elastomer, while TPR is translated from English, strictly speaking called thermoplastic rubber. This is the most basic difference. TPE is generally modified and shaped from SEBS base material, while TPR is made from SBS base material.

Olefinic transparent TPE has good weather resistance and ozone resistance, so it is called the fastest developing variety of TPE, and it is mainly used as a major rubber material in automotive and home appliance fields.

TPE overmolding (secondary injection molding) molding, the key point is to make TPE and the substrate PP, ABS, PC, PA, etc. bond well. To make TPE and the substrate bond well,

Transparent TPE material, due to high light transmittance, requires strict surface quality of the product, no defects such as streaks, air bubbles, whitening, halo, black spots, discoloration, poor gloss, etc. Therefore, throughout the injection molding process, great attention and strict even special requirements must be paid to TPE raw materials, equipment, molds, and even product design.

Transparent TPE is used in stationery, sports equipment, etc. It has good UV resistance, chemical resistance, and easy coloring and processing characteristics.

Juye focuses on the R&D, production and sales of TPE toy materials and TPE soft rubber,

Transparent TPE is used in stationery, sports equipment, etc. It has good UV resistance, chemical resistance, and easy coloring and processing characteristics.

Styrenic transparent TPE is widely used in the footwear industry, largely replacing rubber; at the same time, its use in industrial rubber products such as rubber sheets and plates is also expanding.

TPE elastomer soft gel can be adjusted to the appropriate hardness (hardness range Shore 25-90A) according to the physical property requirements of the product,

The thickness of the TPE, TPR overmolding layer. In most overmolding applications, a wall thickness range of 1.5-3.0mm will ensure good adhesion. If the TPE layer is too thin, injection molding will be difficult, adhesion strength will be low, and the feel will be poor. If the TPE layer is too thick, on one hand the cost is higher, and on the other hand defects such as sink marks and bubbles are prone to occur.

Transparent TPE materials require high light transmittance, so the surface quality of the product must be strictly controlled. No defects such as streaks, pores, whitening, fogging, black spots, discoloration, or poor gloss are allowed. Therefore, during the entire injection molding process, strict and special requirements must be paid to the TPE raw materials, equipment, mold, and even product design.

TPE is used in overmolding, with TPE soft gel as the outer coating layer,

The wall thickness of the TPE layer should be as uniform as possible to achieve the best molding cycle. Transitions between different wall thicknesses should be gradual to reduce flow-related problems such as flow marks and bubbles.

Transparent TPE is used in stationery, sports equipment, etc. It has good UV resistance, chemical resistance, and is easy to color and process.

For secondary injection overmolding of nylon using a regular injection molding machine, it is recommended that before overmolding,

TPE is a classic aggregation-induced emission molecule, meaning it has no fluorescence in solution but strong fluorescence in solid state. Therefore, transparent TPE materials also have important applications in organic optoelectronics and other fields.

Transparent TPE materials have different product properties when applied in different aspects. Thermoplastic elastomer, also known as TPE material, not only has the processing properties of thermoplastic plastics but also the physical properties of vulcanized rubber. This is the advantageous combination of plastic and rubber. Transparent TPE is widely used in people's daily life and production.

TPE overmolding generally adopts a two-shot injection molding process,

SEBS is the product of hydrogenation of SBS. SEBS has a saturated molecular structure, which makes its properties very different. It has the necessary aging resistance, yellowing resistance, and other traits required to produce transparent TPE, and also contributes to excellent high temperature and corrosion resistance. Thus, transparent TPE is produced.

Thickness of TPE, TPR overmolding layer. In most overmolding applications, a wall thickness range of 1.5-3.0mm ensures good adhesion. If the TPE layer is too thin, injection molding is difficult, adhesion strength is low, and hand feel is poor. If the TPE layer is too thick, on one hand the cost is high, and on the other hand, defects like sink marks and bubbles may occur.

TPE overmolding generally uses a two-shot injection molding process, i.e., fixing the molded hard plastic part onto the overmolding mold,

The wall thickness of the TPE layer should be as uniform as possible to achieve the best molding cycle. The transition between different wall thicknesses should be gradual to reduce problems caused by fluid flow, such as gas marks and bubbles.

Transparent grades are divided into transparent and semi-transparent series, each with multiple hardness levels; excellent transparency; smooth and soft surface; good yellowing resistance, tear resistance, and tensile strength; environmentally friendly; suitable for various transparent series products.

TPE is used in overmolding, with TPE soft plastic as the soft outer covering layer,

Because transparent TPE material requires high transmittance, the surface quality of the material product must be strictly controlled, with no defects such as streaks, pores, whitening, haze, black spots, discoloration, poor gloss, etc. Therefore, throughout the injection molding process, strict and even special requirements must be placed on the TPE raw material, equipment, mold, and even product design.

To achieve the matte appearance of thermoset rubber, a rougher mold surface is required. Generally, the rough surface produced by electrical discharge machining (EDM) of the mold cavity will result in an excellent workpiece appearance and make demolding easier. Abrasive methods such as steam blasting, sandblasting, shot blasting, and chemical etching can also be used to produce surfaces with different gloss and appearance.