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Phthalates
Phthalates (US: /ˈθæleɪts/ UK: /ˈ(f)θæleɪtsˌ ˈ(f)θælɪts/), or phthalate esters, are esters of phthalic acid. They are mainly used as plasticizers, i.e., substances added to plastics to increase their flexibility, transparency, durability, and longevity. They are used primarily to soften polyvinyl chloride (PVC). While phthalates are commonly used as plasticizers, not all plasticizers are phthalates. The two terms are specific, unique, and not used interchangeably.
Lower-molecular-weight phthalates are typically replaced in many products in the United States, Canada, and European Union over health concerns. They are being replaced by higher molecular-weight phthalates as well as non-phthalic plasticizers.
Phthalates are commonly ingested in small quantities via the diet. One of the most commonly known phthalates is bis(2-ethylhexyl) phthalate (DEHP). In many countries [which?] DEHP is regulated as a toxin, and is banned from use in broad categories of consumer goods, such as cosmetics, children's toys, medical devices, and food packaging.[citation needed]
There are numerous forms of phthalates not regulated by governments.
Phthalate esters are produced industrially by the reaction of phthalic anhydride with excess alcohol. Often the phthalic anhydride is molten. The monoesterification occurs readily, but the second step is slow:
The conversion is conducted at high temperatures to drive off the water. Typical catalysts are based on tin or titanium alkoxides or carboxylates.
The properties of the phthalate can be varied by changing the alcohol. Around 30 are, or have been, commercially important. Phthalates' share of the global plasticisers market has been decreasing since around 2000 however total production has been increasing, with around 5.5 million tonnes made in 2015, up from around 2.7 million tonnes in the 1980s. The explanation for this is the increasing size of the plasticiser market, largely due driven by increases in PVC production, which nearly doubled between 2000 and 2020. The People's Republic of China is the largest consumer, accounting for around 45% of all use. Europe and the United States together account for around 25% of use, with the remainder widely spread around the world.
Between 90 and 95% of all phthalates are used as plasticisers for the production of flexible PVC. The majority is used in films and cable sheathing. Flexible PVC can consist of over 85% plasticizer by mass[citation needed], however unplasticized PVC (UPVC) should not contain any. Pthalates were the first commercially important compounds for this role, a historic advantage that has led to them becoming firmly embedded in flexible PVC technology. Among the common plastics, PVC is unique in its acceptance of large amounts of plasticizer with gradual changes in physical properties from a rigid solid to a soft gel. Phthalates derived from alcohols with 7–13 carbon atoms occupy a privileged position as general purpose plasticizers, suitable for almost all flexible PVC applications. Phthalates larger than this have limited compatibility in PVC, with di(isotridecyl) phthalate representing the practical upper limit. Conversely, plasticizers derived from alcohols with 4–6 carbon atoms are too volatile to be used on their own, but have been used alongside other compounds as secondary plasticizers, where they improve low-temperature flexibility. Compounds derived from alcohols with 1–3 carbon atoms are not used as plasticizers in PVC at all, due to excessive fuming at processing temperatures (typically 180–210 °C).
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Phthalates
Phthalates (US: /ˈθæleɪts/ UK: /ˈ(f)θæleɪtsˌ ˈ(f)θælɪts/), or phthalate esters, are esters of phthalic acid. They are mainly used as plasticizers, i.e., substances added to plastics to increase their flexibility, transparency, durability, and longevity. They are used primarily to soften polyvinyl chloride (PVC). While phthalates are commonly used as plasticizers, not all plasticizers are phthalates. The two terms are specific, unique, and not used interchangeably.
Lower-molecular-weight phthalates are typically replaced in many products in the United States, Canada, and European Union over health concerns. They are being replaced by higher molecular-weight phthalates as well as non-phthalic plasticizers.
Phthalates are commonly ingested in small quantities via the diet. One of the most commonly known phthalates is bis(2-ethylhexyl) phthalate (DEHP). In many countries [which?] DEHP is regulated as a toxin, and is banned from use in broad categories of consumer goods, such as cosmetics, children's toys, medical devices, and food packaging.[citation needed]
There are numerous forms of phthalates not regulated by governments.
Phthalate esters are produced industrially by the reaction of phthalic anhydride with excess alcohol. Often the phthalic anhydride is molten. The monoesterification occurs readily, but the second step is slow:
The conversion is conducted at high temperatures to drive off the water. Typical catalysts are based on tin or titanium alkoxides or carboxylates.
The properties of the phthalate can be varied by changing the alcohol. Around 30 are, or have been, commercially important. Phthalates' share of the global plasticisers market has been decreasing since around 2000 however total production has been increasing, with around 5.5 million tonnes made in 2015, up from around 2.7 million tonnes in the 1980s. The explanation for this is the increasing size of the plasticiser market, largely due driven by increases in PVC production, which nearly doubled between 2000 and 2020. The People's Republic of China is the largest consumer, accounting for around 45% of all use. Europe and the United States together account for around 25% of use, with the remainder widely spread around the world.
Between 90 and 95% of all phthalates are used as plasticisers for the production of flexible PVC. The majority is used in films and cable sheathing. Flexible PVC can consist of over 85% plasticizer by mass[citation needed], however unplasticized PVC (UPVC) should not contain any. Pthalates were the first commercially important compounds for this role, a historic advantage that has led to them becoming firmly embedded in flexible PVC technology. Among the common plastics, PVC is unique in its acceptance of large amounts of plasticizer with gradual changes in physical properties from a rigid solid to a soft gel. Phthalates derived from alcohols with 7–13 carbon atoms occupy a privileged position as general purpose plasticizers, suitable for almost all flexible PVC applications. Phthalates larger than this have limited compatibility in PVC, with di(isotridecyl) phthalate representing the practical upper limit. Conversely, plasticizers derived from alcohols with 4–6 carbon atoms are too volatile to be used on their own, but have been used alongside other compounds as secondary plasticizers, where they improve low-temperature flexibility. Compounds derived from alcohols with 1–3 carbon atoms are not used as plasticizers in PVC at all, due to excessive fuming at processing temperatures (typically 180–210 °C).