Wednesday, 25 January 2023

Polymer Material Selection Funnel Example - Baby Bottles (Consumer Packing Example)

Polymer Material Selection Funnel Example - Plastic Baby Bottles

Hello and welcome to this new blog post with the topic of polymer material selection. In this post we cover the material selection of baby bottles as an example of the packaging market. We will apply the Polymer Funnel Method (in detail explained here and in this video).

Figure 1 presents the four different stages of the material selection funnel and this overview serves us as a guideline. 

Figure 1: Polymer Selection Funnel - overview of the four different funnel stages 

Before we start, what are the top 10 markets for plastic applications?

The top 10 markets are: 

-Packaging; 

-Building and civil engineering; 

-Automotive and transportation;

-Electrical and electronics; 

-Household, entertainment, and office appliances; 

-Mechanical engineering; 

-Sports and leisure; 

-Medical market; 

-Furniture, and bedding; 

-Agriculture.

Different types of polymers dominate each market. Packing needs high volume and reliability as well as cost effective  commodity polymers, elsewhere Automotive needs engineering and high performance polymers to enable long lasting applications. 

Polymer material selection for baby bottles 

A standard baby bottle consists of the (1) protection cap, (2) suction, (3) ring connector, and (4) the bottle itself. In this example we focus on (4) the bottle itself. For the suction, a FDA food grade silicone was selected.
Four parts of a standard baby bottle (source: https://www.mambaby.com/at/p/easy-active-baby-bottle-330ml-deep-ocean-babyflaschen-kombi/fc2f4zf001-hdt21/)


Funnel stage 1: Material selection factors

The minimum requirements according customer specification are:

  • Fulfillment of EN 14350, regulation 2018/213, and 1895/2005
  • Heat Deflection Temperature of 80°C
  • Impact strength of 100 kJ/m2

Furthermore, in Table 1 we summarized all important requirement information (requirement worksheet).

Table 1: Requirement worksheet for baby bottles.


Funnel stage 2: Decision on thermoplastic or thermoset

Reflecting on the must-have requirements which need to be fulfilled, thermoplastics present the optimal choice. Thermosets will struggle with the regulations, together with the mechanical properties, in particular the impact performance. Amorphous polymers are transparent and have good temperature and mechanical performance. In the meantime,  semi-crystalline polymers are available as transparent food contact grade and polyolefins are particularly interesting since they are globally in high quantities at competitive price available. 

Last step of Funnel stage 2 is the preselection of suitable grades which can be discussed in Funnel stage 3. Table 2 lists all selected grades and their commercial suppliers. The pre-selected materials are Styrene-acrylonitrile resin (SAN), Polyethylene terephthalate (PET), Polycarbonate (PC), and Polypropylene (PP). 

Table 2:  Overview preselected grades and their commercial suppliers.


Funnel stage 3: Selection discussion with worksheet (qualitative matrix analysis)

Now, we have reached the third funnel stage where the matrix analysis takes place. We use the qualitative decision-making process to rank the preselected polymers. 

Table 3 summarizes the outcome of this process. In the first step we rank how good each material can fulfill the requirements (0 to 5=best) and then we assign priorities to each of the requirements (0 to 5 = highest priority). In the last step we multiply the requirement fulfillment with the priority and add the values up. In our case PP (score: 102 points) and PC (score: 95 points) have the highest rank and both materials should be evaluated in Funnel stage 4.  

Table 3: Qualitative matrix analysis for polymer based baby bottles


Funnel stage 4: Testing, selection of material and vendor

In the last funnel stage we will do a part and system component testing with the PP and PC from Funnel stage 3. After that we are able to make a final material selection and vendor respectively. Since public discussion on Bisphenol-A (BPA) as well as Bisphenol-S (BPS) and PC is impacting customer buying decisions due to safety concerns, more and more baby bottle manufacturers use PP instead of PC. In our case, we select PP since it results in a cost-efficient approach due to  less material usage (thinner walls) together with a contribution to lower resource consumption and no risk of BPA/BPS. 

Conclusions
I hope this post helped to understand the Polymer Selection Funnel method by applying it to an example of the consumer market. There will be some more polymer material selection examples where I show the application of the funnel method. 

Thank you and #findoutaboutplastics

Best regards, 
Herwig 


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Literature: 
[1] https://www.compliancegate.com/baby-feeding-bottle-standards-european-union/#EU_Food_Contact_Materials_Framework_Regulation
[2] https://www.borealisgroup.com/news/borealis-brings-a-transparency-boost-to-cosmetics-and-baby-bottles
[4] https://www.packagingtoday.co.uk/news/newsborealis-launches-bpa-free-pp-grade-for-baby-bottles-and-cosmetics-719
[5] https://www.mambaby.com/at/warum-mam/mam-qualit-t-sicherheit/

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