Manejo de isocianatos

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  • Publicado : 7 de mayo de 2011
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CONTENTS

1.0 Introduction

2.0 Construction of Diapers

3.0 Advantages of using Adflex & PP in Diaper construction

3.1 Soft nonwoven lining
3.2 Back Sheets
3.2.1 Case study of A/B/A polypropylene film
3.3 CLOC

4.0 Processing Conditions and Grades

4.1 Soft nonwoven
4.2 Lining film (back sheet)

Advanced Materials

Adflex &Polypropylene in Diaper Construction

1.0 Introduction

Polypropylene is well established as the resin of choice for nonwoven fabrics, used as the inner liner diapers. Adflex, one of Basells advanced polypropylene resins, further enhances the use of polypropylene in the construction of diapers and related feminine hygiene products.

Adflex resins are produced using the Catalloy processtechnology, a sophisticated process technology from Basell. They exhibit low modulus, high softness and have excellent compatibility with other polyolefins.

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Adflex grades can be used in the following areas of Diaper construction:

- Soft nonwoven for the inner liner
- Flexible puncture resistant films for the back sheet
- Low gloss soft nonwovens for Cloth Like Outer Cover (CLOC)

2.0Construction of Diapers

The basic components of a diaper are a nonwoven inner liner, absorbent material (wood pulp) and a back sheet.

• The nonwoven inner layer (next to the baby’s skin) is made from polypropylene. Polypropylene is the resin of choice for the nonwoven inner liner because it serves to keep the surface of the diaper, adjacent to the skin dry and therefore comfortable to wear.• The absorbent material, usually made from treated wood pulp, is used to trap the liquid and keep it away from the skin.

• The back sheet is a thin plastic film and functions as a barrier to any liquids. The film must also be puncture resistant to prevent leaks and or loss of the absorbent material.

At the high quality end of the diaper market, CLOC (cloth like outer cover), a modifiedback sheet is used. These are typically based on a polypropylene nonwoven integrated with the plastic liner (back sheet). The polypropylene nonwoven gives a cloth like feel to the outer surface of the diaper.

3.0 Advantages of using Adflex & PP in Diapers

Basell’s advanced Adflex materials can be used in conjunction with traditional polypropylene and polyethylene materials to modify andimprove the properties of the non-woven, the backsheet and also CLOC diapers. How this can be achieved is outlined below

3.1 Soft nonwoven lining

Adding 15% Adflex to polypropylene fibre grades improves the softness of the polypropylene nonwoven, used in the inner lining and cloth like outer cover. It also improves softness without compromising the mechanical performance of the fibres.Further advantages of using Adflex in the Nonwoven lining:

- Adflex gives a matt finish to the nonwoven, an important feature for CLOC

- Potential for improved bonding strength with PE back sheets due to improved compatibility of Adflex with the PE back sheets.

3.2 Back Sheets

Traditionally back sheets are made from polyethylene (LLDPE/LDPE blends). With the advent of 3 layer coextrusiontechnology for films and the use of Adflex as a compatibliser it is possible to produce a three layer coextruded film, A/B/A construction consisting of (PE / RCP+Adflex / PE).

25% A: LDPE + LLDPE (80/20)
50% B: Adflex C200F + RACO PP (20/80)
25% C: LDPE + LLDPE (80/20)

Three layer coextruded film (PE / RCP+Adflex / PE) offers the following attributes:

- Good strength and punctureresistance
- High modulus that enables down gauging
- Less shrinking and curling when in contact with hot melt glue
- Easily coloured with conventional PP and PE colour concentrates
- Film scrap can be recycled
- Maintains existing skin layers and surface characteristics

The higher stiffness (modulus) of the coextruded PP based film allows the film to be down gauged. In practice the...
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