Technical requirements of polyester bottles for th

Technical requirements for polyester bottles for water packaging

drinking water includes mineral water, purified water, soda water, etc. In recent years, in order to ensure the high quality of drinking water and the effectiveness of packaging, and strengthen the competitiveness of brands in the market, higher requirements have been put forward for polyester bottles for water packaging, some of which have become the internal control indicators of some companies

1. Acetaldehyde content

as a bottle polyester resin chip, its quality standard specifies the acetaldehyde content, which is <1 ×， This index can be achieved by almost all polyester bottle chip manufacturers. However, the acetaldehyde content in the resin increases after injection molding into the bottle blank. Therefore, it is proposed to control the acetaldehyde content in the resin of the bottle blank in this 10 × The following (coke bottle requirements 5 × Below). However, some domestic water bottle manufacturers ignore this requirement, and the content of acetaldehyde mixed is (60~150) × Bright polyester chips, which leads to the content of acetaldehyde in water bottles exceeding the standard by several times to more than ten times, this is an abnormal situation, and will not be discussed. The acetaldehyde content in polyester bottle blanks increases. In addition to the factors of injection molding equipment and technology, the quality of polyester bottle chips is the main factor. It is understood that from the 1980s to the mid-1990s, the acetaldehyde content of bottle blanks produced from domestic bottle polyester chips is generally (8 ~ 15) ×， Coke bottle requirements 5 × Below, that is, or later changed to (6 ~ 8) × It is difficult to meet the requirements of

in recent years, Danone, Nestle and other companies have also proposed that the acetaldehyde content of water bottle preforms is less than 5 × (even 3 ×) High requirements

2. Formaldehyde

some European drinking water companies also invited graphene technology exhibition to Shenzhen feirongda, cecep solar energy technology (Zhenjiang) Co., Ltd., Ningbo CSR new energy and other downstream graphene utilization enterprises to put forward a new requirement for polyester bottles - formaldehyde, that is, after filling water, detect the formaldehyde content in water, and the requirement is <10 × (that is <10ppb =

the formaldehyde in the water comes from the resin constituting the polyester bottle, so we need to find out the source of formaldehyde in the polyester resin. It is known that methanol is oxidized to form formaldehyde, and some organic substances can also be decomposed or oxidized and burned to produce formaldehyde. In addition, under certain conditions, no matter which location is selected, carbon monoxide can be hydrogenated to synthesize formaldehyde. At the same time, it is also known that these reactions may occur in the process of resin synthesis and tackifying under the following circumstances:

(1) dimethyl terephthalate is used as the raw material for the opinions of the Ministry of public security that is greater than or equal to 30 in the future

(2) the main reason for the growth of the company's deeds is that the price of raw material waste stainless steel increased by 6.8% month on month in the first quarter, using trimethyl phosphate and other additives with methoxy groups

(3) organic matter in combustion gas flow during viscosity increase

(4) when viscosity is increased, hydrogenation is adopted to remove oxygen, and excess hydrogen reacts with carbon monoxide generated by burning organic matter. Thus, the polyester resin contains formaldehyde

3. bottle expansion test

it is understood that Russia and other countries should do the test of inflatable bottle expansion test on water bottles, because they want to use polyester bottles of soda water. Test conditions: fill water to a certain height, fill carbon dioxide to 0.35Mpa, put it in an oven at 40 ℃ for 24h, and observe the change of water height in the bottle. Generally, the height change is less than 2%. The crystallization behavior of polyester resin is closely related to the bottle size. (text/Yang Shi)