阅读说明：本技术 环保耐热乳酸塑料奶瓶的制作工艺 (Manufacturing process of environment-friendly heat-resistant lactic acid plastic feeding bottle ) 是由 全威 盛智 于 2020-05-30 设计创作，主要内容包括：本发明公开了一种环保耐热乳酸塑料奶瓶的制作工艺,工艺如下：在聚左旋乳酸塑料中添加有机成核剂并造粒均混；确定管坯模具形状并调整模温；低速管坯注塑；通过单片机控制管坯非均衡软化；用热空气吹塑法吹塑成形；退火重结晶。优点是：本发明利用单片机来控制管坯侧面加热装置的温度,再加上选择性加热与转速的配合,让管坯上产生需要的温差,这样可以在吹塑时满足其双向拉伸要求；采用聚左旋乳酸作为原料在使用报废后降解,相比其它原料不但更加环保、成本更低,而且其在制备中采用的微波退火处理能提高结晶度,稳定结晶状态,提高产品的耐热性能。(The invention discloses a manufacturing process of an environment-friendly heat-resistant lactic acid plastic feeding bottle, which comprises the following steps: adding an organic nucleating agent into the poly-L-lactic acid plastic, and granulating and uniformly mixing; determining the shape of a tube blank die and adjusting the die temperature; injection molding of the low-speed tube blank; controlling the unbalanced softening of the tube blank by a singlechip; blow molding by hot air blow molding; and (5) annealing and recrystallizing. The advantages are that: the invention utilizes the singlechip to control the temperature of the heating device on the side surface of the tube blank, and the cooperation of selective heating and rotating speed, so that the required temperature difference is generated on the tube blank, and the requirement of biaxial tension can be met during blow molding; the poly-L-lactic acid is used as a raw material and is degraded after being discarded, compared with other raw materials, the poly-L-lactic acid is more environment-friendly and lower in cost, and the microwave annealing treatment adopted in the preparation can improve the crystallinity, stabilize the crystallization state and improve the heat resistance of the product.)

1. The manufacturing process of the environment-friendly heat-resistant lactic acid plastic feeding bottle is characterized by comprising the following steps of: the manufacturing process comprises the following steps:

a. mixing and granulating: adding an organic nucleating agent into the poly-L-lactic acid plastic, granulating and uniformly mixing, wherein the proportion of the organic nucleating agent is controlled to be 0.4-2.5%;

b. moulding the tube blank: determining the shape of a die of the tube blank, wherein the blow-up ratio is 7-10: 1, the hoop stretch ratio is 2-5.5: 1, and the axial stretch ratio is 1-4: 1;

c. injection molding of the tube blank: injecting the mixed raw materials into a mold cavity through a tube blank injection molding machine in a temperature and pressure combined mode, wherein the temperature of a charging barrel of the tube blank injection molding machine is set to be between 150 and 220 ℃, the temperature of a feeding section is set to be between 145 and 170 ℃, the mold temperature of the mold is controlled to be between 40 and 60 ℃, and low-speed injection is adopted;

d. preheating the side surface of the tube blank: controlling a heating device on one side of the tube blank to emit heat through a singlechip, so that the tube blank is subjected to unbalanced softening during revolution and rotation, and the softening temperature is 40-60 ℃;

e. blow molding: heating a blow molding mould to 110-160 ℃, placing the softened mouth of the tube blank at the corresponding mouth position in the blow molding mould for positioning, and then performing blow molding by adopting a hot air blow molding method and maintaining the constant temperature;

f. annealing and recrystallizing: the mouth of the feeding bottle is sleeved on a microwave heating device, and the mouth of the feeding bottle is annealed under the action of microwaves and then recrystallized.

2. The manufacturing process of the environment-friendly heat-resistant lactic acid plastic feeding bottle according to claim 1, characterized in that: in the step a, the organic nucleating agent accounts for 0.65 percent.

3. The manufacturing process of the environment-friendly heat-resistant lactic acid plastic feeding bottle according to claim 2, characterized in that: the mold temperature of the mold in the step c is 50 ℃.

4. The manufacturing process of the environment-friendly heat-resistant lactic acid plastic feeding bottle according to claim 3, characterized in that: and d, controlling the position and the temperature of the infrared neon tube and the revolution and autorotation speed of the tube blank by the singlechip.

5. The manufacturing process of the environment-friendly heat-resistant lactic acid plastic feeding bottle according to claim 4, characterized in that: the blow molding in the step e is as follows: the tube blank maintains relatively stable temperature in the blow molding process, and is subjected to biaxial stretching in the environment and polylactic acid crystallization is realized.

Technical Field

The invention belongs to the technical field of manufacturing of polylactic acid bottles, and particularly relates to a manufacturing process of an environment-friendly heat-resistant lactic acid plastic feeding bottle.

Background

At present, products which develop biodegradable polymers to replace petroleum-based polymers are continuously emerged, on one hand, the biodegradable polymers are derived from renewable natural biomass resources such as starch, plant straws and the like, and the biodegradable polymers replace the plastic of the polymers of petroleum, so that the consumption of the petroleum resources can be reduced by 30-50 percent, the dependence of people on the petroleum resources is reduced, and the energy crisis of the petroleum at present is relieved; on the other hand, carbon dioxide and water are consumed in the whole production process (the filler is changed into starch through photosynthesis), so that the emission of carbon dioxide can be reduced, and the reduction of the greenhouse effect of the atmosphere is facilitated; the biodegradable polymer product can be composted together with other organic wastes, thus avoiding the harsh classification treatment method of petroleum-based polymer plastic products.

The biodegradable polymer mainly comprises a biodegradable polymer synthesized by microorganisms, natural products and chemical synthesis, wherein polylactic acid (PLA) is the only biodegradable polymer synthesized by chemical synthesis and taking biological resources as raw materials and is the degradable raw material with the largest dosage and the widest application at present.

However, the main factors restricting the use of PLA are performance and price, and in the case of PLA, outstanding disadvantages such as problems of toughness, heat resistance, etc. are noted. PLA polylactic acid can be divided into two types, namely PLLA and PDLA, according to molecular structures, the PLLA is in a levorotatory PLA structure, the PDLA is in a dextrorotatory PLA structure, the heat resistance of the PDLA is well solved, but the price of the PDLA is more than three times that of the PLLA, and the application limitation is obvious.

Due to the above factors, poly-L-lactic acid is mainly used for refrigerating non-carbonic acid and packaging in short-term shelf life in the field of food packaging, such as mineral water and fresh orange juice, high-cost PDLA polylactic acid or other biodegradable materials specially treated are required to be adopted for hot drinks such as hot milk, and compared with the PC milk bottle, PP milk bottle or glass milk bottle which are commonly used at present, the PC milk bottle is worn and aged after repeated disinfection, BPA (bisphenol containing additive carcinogen is increased), dissolved out at the time, the PP milk bottle has the lowest toxicity in petroleum-based food packaging products, but still decomposes trace toxin at continuous high temperature, and as the milk bottle for self-feeding of infants, the strength of the PP milk bottle is not optimal, the bending strength and hardness are lower, and the glass milk bottle has the defects of heat insulation and frangibility, and is only suitable for adult feeding, so improvement is needed.

Disclosure of Invention

The invention aims to provide a manufacturing process of an environment-friendly heat-resistant lactic acid plastic feeding bottle aiming at the defects in the prior art, and the bottle produced by the process has the characteristics of environment friendliness, heat resistance and degradability.

In order to achieve the purpose, the invention adopts the technical scheme that: a manufacturing process of an environment-friendly heat-resistant lactic acid plastic feeding bottle comprises the following steps:

a. mixing and granulating: adding an organic nucleating agent into the poly-L-lactic acid plastic, granulating and uniformly mixing, wherein the proportion of the organic nucleating agent is controlled to be 0.4-2.5%;

b. moulding the tube blank: determining the shape of a die of the tube blank, wherein the blow-up ratio is 7-10: 1, the hoop stretch ratio is 2-5.5: 1, and the axial stretch ratio is 1-4: 1;

c. injection molding of the tube blank: injecting the mixed raw materials into a mold cavity through a tube blank injection molding machine in a temperature and pressure combined mode, wherein the temperature of a charging barrel of the tube blank injection molding machine is set to be 170-200 ℃, the temperature of a feeding section is 145-170 ℃, the mold temperature of the mold is controlled to be 40-60 ℃, and low-speed injection is adopted;

d. preheating the side surface of the tube blank: controlling a heating device on one side of the tube blank to emit heat through a singlechip, so that the tube blank is subjected to unbalanced softening during revolution and rotation, and the softening temperature is 40-60 ℃;

e. blow molding: heating a blow molding mould to 110-160 ℃, placing the softened mouth of the tube blank at the corresponding mouth position in the blow molding mould for positioning, and then performing blow molding by adopting a hot air blow molding method and maintaining the constant temperature;

f. annealing and recrystallizing: the mouth of the feeding bottle is sleeved on a microwave heating device, and the mouth of the feeding bottle is annealed under the action of microwaves and then recrystallized.

In the step a, the organic nucleating agent accounts for 0.65 percent.

The mold temperature of the mold in the step c is 50 ℃.

And d, controlling the position and the temperature of the infrared neon tube and the revolution and autorotation speed of the tube blank by the singlechip.

The blow molding in the step e is as follows: the tube blank maintains relatively stable temperature in the blow molding process, and is subjected to biaxial stretching in the environment and polylactic acid crystallization is realized.

Compared with the prior art, the invention has the advantages that: according to the invention, the temperature of the heating device on the side surface of the tube blank is controlled by using the PLC, and the required temperature difference is generated on the tube blank by matching the selective heating with the rotating speed, so that the requirement of biaxial tension can be met during blow molding; the poly-L-lactic acid is used as a raw material and is degraded after being discarded, compared with other raw materials, the poly-L-lactic acid is more environment-friendly and lower in cost, and the microwave annealing treatment adopted in the preparation can improve the crystallinity, stabilize the crystallization state and improve the heat resistance of the product.

Detailed Description

The following description is only a preferred embodiment of the present invention, and does not limit the scope of the present invention.

Example 1: a manufacturing process of a poly-L-lactic acid bottle comprises the following steps:

a. mixing and granulating: adding an organic nucleating agent into the poly-L-lactic acid plastic, granulating and uniformly mixing, wherein the proportion of the organic nucleating agent is 0.65%; the organic nucleating agent can not only improve the crystallization speed of the poly-L-lactic acid plastic, shorten the molding cycle of the product and improve the production efficiency, but also improve the heat resistance and the shock resistance of the product;

b. moulding the tube blank: determining the shape of a die of the tube blank, wherein the shape of the die is determined according to the actual production requirements, and under the common conditions, the blow-up ratio is preferably 7-10: 1, the hoop stretching ratio is preferably 2-5.5: 1, and the axial stretching ratio is preferably 1-4: 1;

c. injection molding of the tube blank: injecting the mixed raw materials into a mold cavity through a tube blank injection molding machine in a temperature and pressure combined mode, wherein the temperature of a charging barrel of the tube blank injection molding machine is set to be 185 ℃, the temperature of a feeding section is set to be 165 ℃, and the mold temperature of the mold is preferably 50 ℃; thus, degradation caused by long-time high-temperature melting can be effectively avoided, and the aim of inhibiting crystallization is fulfilled; when the tube blank is injected, low-speed injection is adopted to avoid the phenomenon of local shear degradation, and the tube blank is formed under the condition of no degradation or crystallization;

d. preheating the side surface of the tube blank: the tube blank needs to be heated and softened, so that a heating device on one side of the tube blank is controlled by a single chip microcomputer to generate heat, the heating device is an infrared neon tube, the tube blank is subjected to unbalanced softening under the action of the infrared neon tube during revolution and rotation, the softening temperature is lower than the vitrification temperature, namely lower than 65 ℃, the temperature is usually between 40 and 60 ℃, and the temperature is usually 50 ℃; the temperature difference of the unbalanced softening of the tube blank is adjusted by the temperature, the position and the heating time of the infrared neon tube, and the temperature difference of each position is determined according to the subsequent blow molding effect; the autorotation of the tube blank can ensure that the circumferential surface at the same height has balanced temperature, thereby facilitating the subsequent blow molding;

e. blow molding: heating a blow molding mould to 110-160 ℃, placing the softened mouth of the tube blank at the corresponding mouth position in the blow molding mould for positioning, wherein the temperature is usually 65-80 ℃, and then performing blow molding by adopting a hot air blow molding method, wherein the hot air blow molding method can relatively balance the internal and external temperatures of the tube blank during blow molding compared with the traditional air blow molding method and maintain the relatively balanced temperature;

f. annealing and recrystallizing: sleeving the bottle mouth of the feeding bottle on a microwave heating device, enabling polylactic acid molecules with thick bottle mouth to realize thermal motion under the action of microwaves, and enabling the original non-uniform crystals to be disintegrated and stable alpha crystals to be obtained again through high-temperature annealing; after the completion, the microwave heating device can automatically cut off the microwave power supply and turn on the reminding lamp.

The invention utilizes the singlechip to control the temperature of the heating device on the side surface of the tube blank, and the cooperation of selective heating and rotating speed, so that the required temperature difference is generated on the tube blank, and the requirement of biaxial tension can be met during blow molding; the poly-L-lactic acid is used as a raw material and is degraded after being discarded, compared with other raw materials, the poly-L-lactic acid is more environment-friendly and lower in cost, and the microwave annealing treatment adopted in the preparation can improve the crystallinity, stabilize the crystallization state and improve the heat resistance of the product.

Example 2, the process steps of example 2 are substantially the same as example 1, except that: in the step a, the organic nucleating agent accounts for 0.5 percent; the mold temperature of the mold in the step b is 45 ℃; the same effects as in example 1 can be obtained.

Example 3, the process steps of example 3 are essentially the same as example 1, with the following exceptions: in the step a, the organic nucleating agent accounts for 2 percent; the mold temperature of the mold in the step b is 55 ℃; the same effects as in example 1 can be obtained.