Classical Interpretation of Food Grade TPE/TPR Test
Source：德创化工Time：2019-12-21Hits：2873
Food grade has always been the focus topic of TPE industry. This issue has been paid attention to by the industry and consulted by users. It also confirms the potential demand of food grade TPE and the difficulty of TPE passing relevant food grade tests. This article discusses the issue of TPE food grade, hoping to be helpful to the industry. TPE discussed today is a blend modified material based on SBC styrene elastomer.
The transparency of TPE and TPR materials depends on the components of the blending system. As long as the proper SEBS and SBS base materials are selected, the proper plastic (such as PP and PS) grades are selected, and no filler, toner, flame retardant and other functional additives are added, transparent TPE and TPR particles can be prepared by blending. However, the transparency of TPE and TPR materials will be affected by the differences in the specific brand specifications and the distribution ratio of each component of the system.
TPE's full English name is Themoplasticstomer, and its Chinese name is themoplasticelastomer. TPR's English name is themoplastic rubber and its Chinese name is thermoplastic rubber. It all means the same thing. Generally, older people prefer TPR, while younger people prefer TPE. Sometimes the name varies from region to region. TPR, TPE is a kind of thermoplastic elastomer with the characteristics of high elasticity, high strength, high resilience of rubber and injection molding. It has the advantages of environmental protection, innocuity, safety, wide hardness range, excellent coloration, soft touch, weather resistance, fatigue resistance and temperature resistance, excellent processing performance, no need of vulcanization, recycling, cost reduction, secondary injection molding, coating and bonding with PP, PE, PC, PS, ABS and other matrix materials, or forming separately. Thermoplastic elastomer not only has the processability of thermoplastic, but also has the physical properties of vulcanized rubber, which can be described as an advantageous combination of the advantages of plastic and rubber.
I. Food Grade TPE Understood by Some Public
Some users will habitually put forward a concept of food-grade requirements for TPE materials when they first receive orders for food-contact packaging products. However, due to their lack of understanding of food-grade testing standards, the concept and requirements of food-grade TPE may be relatively vague.
II. Different Food Grade Testing Standards for TPE
First, different countries or regions have different food-grade testing industry standards. Second, different testing methods are available for different types of food contact grade materials. For example, the European Union's inspection standard for food contact materials is EC/1935/2004, while within the EU member states, some countries even have their own special testing standards. For example, Germany's food-grade inspection standard is LFGB. France's is French DGCC RF 2004-64. As for the United States, FDA agencies formulate food-grade testing items and standards for corresponding materials.
III. Confirmation of Food Level Testing Standards for TPE Materials/Products
The general principle is to determine the food-grade testing standards in accordance with the region where the products are exported. For example, if the products are exported to the United States, the large framework will naturally conform to FDA food-grade testing standards. If the products are exported to the European Union, they will naturally conform to EC/1935/2004. Sometimes, the specific testing items will vary according to different products and exporting countries.
For example, the TPE test standard for food-grade contact materials commonly used in the European Union mainly tests the water alcoholic acid (distilled water, 50% alcohol, 3% acetic acid, and the concentration of solvent may be different for different material tests) for dissolution test. However, Germany's LFGB has oil (olive oil) test items in addition to the water alcoholic acid test.
Another example is FDA food-grade testing standards in the United States. For TPE, 21CFR177.2600 test standard is adopted. In principle, distilled water and n-hexane should be tested. However, the standard also states that the n-hexane test is mainly aimed at TPE materials and products exposed to fatty foods. In fact, most of the time, users' TPE products may only come into contact with some non-oily, packaged food, without the need for n-hexane testing. However, end customers need to provide FDA inspection reports, which has puzzled TPE material and product suppliers in the industry for a period of time. At present, some TPE suppliers and users only test distilled water instead of n-hexane when making TPE products that do not need contact with fatty and oily foods, which strictly does not conform to FDA177.2600 standard. However, some of our users who are not too harsh also accepted it. Fortunately, there is no potential adverse impact on food and consumer safety during the use of such products. But for some contact with meat, rice, oily hot soup food and so on, you must do n-hexane test, which is also responsible for consumers.
IV. Feasibility and Difficulty of TPE Passing Various Food Grade Testing Projects
Schematic Diagram of Difficulty in Dissolution Test of Food Contact Material TPE TPR
For TPE, detection of all kinds of heavy metals and REACH(SVHC) is not a problem. It is mainly focused on dissolution of small molecules and is a key test item. Dissolution test is mainly discussed here.
1, distilled water test
Most TPE can pass this item. As long as TPE compounds that are not too garbage or recycled TPE materials are not used, there is basically no problem.
2, alcohol acid test
It mainly refers to the tests of ethanol (alcohol) and acetic acid. Different countries or regions may have slightly different test standards. The selected solvents and concentrations are different, but the test purposes are the same. Yamamoto thought this was mainly aimed at some TPE products for beverage packaging. It is very difficult to pass this item. The choice of TPE compound is very important. Attention should also be paid to equipment cleaning and the introduction of additional substances during product processing. Of course, if the mixing system is proper, there are still a few TPE that can pass the dissolution test of alcohol and acid.
3, oil test
Mainly refers to olive oil (for LFGB in Germany) and n-hexane (for FDA and other testing standards using this solvent, such as GB in China). Almost none of TPE and TPR can pass the dissolution test of these two types of oily solvents (some senior people in the industry think that the n-hexane test is more difficult than the olive oil test). It is said that a few foreign TPE enterprises have materials with hardness above 60~70A and TPE brands that can pass the tests of olive oil and n-hexane, but whether they are SBC-based TPE has not yet been verified.
In addition to the above two oily solvents, other national food-grade test standards, dissolution test solvents, have used n-heptane, or isooctane, etc.
