Plastic housing Product Description

Plastic seat with unique light weight, easy to install, maintenance-free , but with a common cast iron seat or seats that are not stamped with a damping impact resistance. With the continuous development of new materials , plastic seat being increasingly widely used in engineering . For different situations , plastic spherical bearing can be POM, HDPE, PP, UPE, PTFE and other different materials, commonly used PBT plastic housing material .

PBT Introduction

Poly (butylene terephthalate) , the English name polybutylece terephthalate ( referred to as PBT), a polyester series , is a 1.4 - butanediol (1.4-Butylene glycol) and terephthalic acid (PTA) or dimethyl terephthalate ester (DMT) poly condensation, and made ​​through the mixing process is translucent to opaque white , crystalline thermoplastic polyester resin. Collectively together with PET thermoplastic polyester , or polyester.

The advantages of this material : a toughness good , not broken .

                    Note 2 streams good performance , easy molding .

                   3 relatively inexpensive phenolic material

The disadvantage of this material : no heat , when the temperature deformation

PBT physicochemical properties

PBT is translucent to opaque white , crystalline thermoplastic polyester. With high heat resistance, toughness , fatigue resistance , self-lubricating , low friction coefficient , weather resistance , low water absorption , only 0.1 % in wet conditions remain variety of physical properties ( including electrical properties ) , electrical insulation, but volume resistivity and dielectric loss big . Heat water, alkalis, acids, oils , halogenated hydrocarbons but are vulnerable to erosion , poor water resistance , low temperature can be rapidly crystallized, forming good . The disadvantage is that the notched impact strength low mold shrinkage . Therefore, most of the glass fiber reinforced or modified inorganic filler , the tensile strength, flexural strength can be increased more than doubled, heat distortion temperature also greatly improved. You can work long at 140 ℃, glass fiber reinforced products after longitudinal and transverse shrinkage consistent , easy to make products warpage.

PBT Process

PBT thermoplastic polyester plastics can be called , is applicable to different processing industries , the general number of additives are added or blended with other plastics , as additives in different proportions , can produce different specifications. PBT has the heat resistance, weather resistance, chemical resistance , good electrical properties , low water absorption , good luster, widely used in electronic appliances, auto parts, machinery , household goods , etc., and PBT products and with PPE, PC, POM, PA and so were called the five pan with plastic .

PBT crystallization speed , the most suitable processing method for injection molding, as well as other methods of extrusion, blow molding, coating and various secondary processing molding , molding required before pre-drying , moisture content should be reduced to 0.02 %.

PBT injection molding process characteristics and process parameters can be set :

PBT polymerization process maturity, low cost, easy molding. Unmodified PBT poor performance , the practical application of PBT to be modified , in which glass fiber reinforced modified grades accounted for more than 70% PBT 's .

1 PBT technology features of

PBT has a sharp melting point , melting point of 225 ~ 235 ℃, is a crystalline material , the degree of crystallinity of up to 40 %.

PBT melt viscosity is not as affected by temperature shear stress so much so , in injection molding , injection pressure PBT melt flow impact is obvious .

PBT fluidity in the molten state , low viscosity, second only to nylon molding prone to " cast " phenomenon.

PBT molding products anisotropy. PBT at high water readily biodegradable .

2 injection molding machine

Selection of the screw -type injection molding machine. Should consider the following points .

①products should be controlled by feeding 30% to 80% of the injection molding machine rated maximum amount . Not with a large injection molding machine to produce small products.

②should use tapered screw three sections , the aspect ratio of 15 to 20 , the compression ratio of 2.5 to 3.0.

③should use self-locking nozzle and heating temperature control device .

④When the forming flame retardant PBT, injection molding machine related parts should embalmed .

3 product and mold design

①thickness of the article should not be too thick , PBT is very sensitive to the gap , so the transition at right angles and other products should be used to connect the arc .

②unmodified PBT molding shrinkage rate of the larger , 1.7 % ~ 2.3% , have a certain mold stripping slope .

③mold needs to vent or exhaust ducts located .

④gate diameter should be larger.

⑤mold temperature control device to be set . High mold temperatures can exceed 100 ℃.

⑥Flame Retardant PBT molding, the mold surface to chrome to corrosion .

4 raw material preparation

Dried prior to injection , to control the moisture content below 0.02%. When using hot air drying cycle , when the temperature is 105 ℃, 120 ℃or 140 ℃, the time corresponding to no more than 6h, 4h, 2h. Material thickness less than 30mm.

Five injection molding process parameters

①PBT injection temperature decomposition temperature of 280 ℃, and actual production is generally controlled between 235 ~ 245 ℃.

②injection pressure, injection pressure is generally 50 ~ 100MPa.

③injection rate PBT cooling speed , and therefore faster injection rate.

④screw speed and back pressure molding PBT screw speed should not exceed 80r/min, generally between 25 ~ 60r/min. Back pressure is generally 10% to 15% of the injection pressure .

⑤mold temperature control in 70 ~ 80 ℃, the temperature of each part of the difference does not exceed 10 ℃.

⑥molding cycle under normal circumstances is 15 ~ 60 s.

6 Precautions

①the use of recycled material and new material proportion of recycled materials is generally 25% to 75%.

②use of the releasing agent is not used under normal circumstances the release agent, silicone release agent may be used when necessary .

③stop processing PBT downtime in less than 30min, can be shut down when the temperature drops to 200 ℃. After a long shutdown of production , the material inside the barrel emptying want , then add new material to normal production .

④products after processing generally does not require treatment , if necessary, treatment 1 ~ 2h at 120 ℃, .

Plastic housing Product Description

Plastic seat with unique light weight, easy to install, maintenance-free , but with a common cast iron seat or seats that are not stamped with a damping impact resistance. With the continuous development of new materials , plastic seat being increasingly widely used in engineering . For different situations , plastic spherical bearing can be POM, HDPE, PP, UPE, PTFE and other different materials, commonly used PBT plastic housing material .

PBT Introduction

Poly (butylene terephthalate) , the English name polybutylece terephthalate ( referred to as PBT), a polyester series , is a 1.4 - butanediol (1.4-Butylene glycol) and terephthalic acid (PTA) or dimethyl terephthalate ester (DMT) poly condensation, and made ​​through the mixing process is translucent to opaque white , crystalline thermoplastic polyester resin. Collectively together with PET thermoplastic polyester , or polyester.

The advantages of this material : a toughness good , not broken .

                    Note 2 streams good performance , easy molding .

                   3 relatively inexpensive phenolic material

The disadvantage of this material : no heat , when the temperature deformation

PBT physicochemical properties

PBT is translucent to opaque white , crystalline thermoplastic polyester. With high heat resistance, toughness , fatigue resistance , self-lubricating , low friction coefficient , weather resistance , low water absorption , only 0.1 % in wet conditions remain variety of physical properties ( including electrical properties ) , electrical insulation, but volume resistivity and dielectric loss big . Heat water, alkalis, acids, oils , halogenated hydrocarbons but are vulnerable to erosion , poor water resistance , low temperature can be rapidly crystallized, forming good . The disadvantage is that the notched impact strength low mold shrinkage . Therefore, most of the glass fiber reinforced or modified inorganic filler , the tensile strength, flexural strength can be increased more than doubled, heat distortion temperature also greatly improved. You can work long at 140 ℃, glass fiber reinforced products after longitudinal and transverse shrinkage consistent , easy to make products warpage.

PBT Process

PBT thermoplastic polyester plastics can be called , is applicable to different processing industries , the general number of additives are added or blended with other plastics , as additives in different proportions , can produce different specifications. PBT has the heat resistance, weather resistance, chemical resistance , good electrical properties , low water absorption , good luster, widely used in electronic appliances, auto parts, machinery , household goods , etc., and PBT products and with PPE, PC, POM, PA and so were called the five pan with plastic .

PBT crystallization speed , the most suitable processing method for injection molding, as well as other methods of extrusion, blow molding, coating and various secondary processing molding , molding required before pre-drying , moisture content should be reduced to 0.02 %.

PBT injection molding process characteristics and process parameters can be set :

PBT polymerization process maturity, low cost, easy molding. Unmodified PBT poor performance , the practical application of PBT to be modified , in which glass fiber reinforced modified grades accounted for more than 70% PBT 's .

1 PBT technology features of

PBT has a sharp melting point , melting point of 225 ~ 235 ℃, is a crystalline material , the degree of crystallinity of up to 40 %.

PBT melt viscosity is not as affected by temperature shear stress so much so , in injection molding , injection pressure PBT melt flow impact is obvious .

PBT fluidity in the molten state , low viscosity, second only to nylon molding prone to " cast " phenomenon.

PBT molding products anisotropy. PBT at high water readily biodegradable .

2 injection molding machine

Selection of the screw -type injection molding machine. Should consider the following points .

①products should be controlled by feeding 30% to 80% of the injection molding machine rated maximum amount . Not with a large injection molding machine to produce small products.

②should use tapered screw three sections , the aspect ratio of 15 to 20 , the compression ratio of 2.5 to 3.0.

③should use self-locking nozzle and heating temperature control device .

④When the forming flame retardant PBT, injection molding machine related parts should embalmed .

3 product and mold design

①thickness of the article should not be too thick , PBT is very sensitive to the gap , so the transition at right angles and other products should be used to connect the arc .

②unmodified PBT molding shrinkage rate of the larger , 1.7 % ~ 2.3% , have a certain mold stripping slope .

③mold needs to vent or exhaust ducts located .

④gate diameter should be larger.

⑤mold temperature control device to be set . High mold temperatures can exceed 100 ℃.

⑥Flame Retardant PBT molding, the mold surface to chrome to corrosion .

4 raw material preparation

Dried prior to injection , to control the moisture content below 0.02%. When using hot air drying cycle , when the temperature is 105 ℃, 120 ℃or 140 ℃, the time corresponding to no more than 6h, 4h, 2h. Material thickness less than 30mm.

Five injection molding process parameters

①PBT injection temperature decomposition temperature of 280 ℃, and actual production is generally controlled between 235 ~ 245 ℃.

②injection pressure, injection pressure is generally 50 ~ 100MPa.

③injection rate PBT cooling speed , and therefore faster injection rate.

④screw speed and back pressure molding PBT screw speed should not exceed 80r/min, generally between 25 ~ 60r/min. Back pressure is generally 10% to 15% of the injection pressure .

⑤mold temperature control in 70 ~ 80 ℃, the temperature of each part of the difference does not exceed 10 ℃.

⑥molding cycle under normal circumstances is 15 ~ 60 s.

6 Precautions

①the use of recycled material and new material proportion of recycled materials is generally 25% to 75%.

②use of the releasing agent is not used under normal circumstances the release agent, silicone release agent may be used when necessary .

③stop processing PBT downtime in less than 30min, can be shut down when the temperature drops to 200 ℃. After a long shutdown of production , the material inside the barrel emptying want , then add new material to normal production .

④products after processing generally does not require treatment , if necessary, treatment 1 ~ 2h at 120 ℃, .