Plastic products are made from many different polymers, and each behaves differently during sorting, washing, shredding, separation, and reprocessing. Correctly identifying the plastic type is therefore one of the most important steps in any recycling operation.

The numbers commonly found on plastic products—from 1 to 7—are known as Resin Identification Codes (RICs). They help identify the primary resin used to manufacture a plastic article.

빠른 답변: Plastic numbers 1–7 identify different resin categories. They do not automatically mean that a product is recyclable. Actual recyclability depends on the polymer, product design, contamination level, collection system, and available recycling technology.

For recyclers, understanding these plastic types also helps determine which sorting method, washing process, shredder, crusher, separator, and pelletizing system should be used.

What Do Plastic Recycling Numbers Mean?

The Resin Identification Code system was originally developed to help identify different plastic resins and support sorting.

The seven main categories are:

PET or PETE — Polyethylene Terephthalate
HDPE — High-Density Polyethylene
PVC — Polyvinyl Chloride
LDPE — Low-Density Polyethylene
PP — Polypropylene
추신 — Polystyrene
OTHER — Other plastics such as ABS, PC, PA, PMMA, PLA, and multilayer materials

It is important to distinguish a resin identification code from a recycling claim. According to ASTM D7611/D7611M, the code identifies the plastic resin used in an article; the presence of a code does not guarantee that the product can or will be recycled.

Plastic Types 1–7: Quick Comparison

암호	플라스틱	Typical Density*	Behavior in Water	일반적인 응용 프로그램	Recycling Difficulty
#1	애완 동물	1.34–1.39 g/cm³	Sinks	Beverage bottles, food containers, polyester	낮음-중간
#2	HDPE	0.94–0.97 g/cm³	Floats	Bottles, drums, crates, pipes	낮은
#3	PVC	~1.16–1.45+ g/cm³	Usually sinks	Pipes, profiles, flooring, cable insulation	Medium–High
#4	LDPE	0.91–0.94 g/cm³	Floats	Film, bags, shrink wrap	중간
#5	PP	0.89–0.92 g/cm³	Floats	Caps, crates, containers, woven bags	낮음-중간
#6	추신	~1.04–1.07 g/cm³	Rigid PS usually sinks	HIPS products, trays, EPS foam	Medium–High
#7	OTHER	다양하다	다양하다	ABS, PC, PA, PMMA, PLA, multilayer plastics	다양하다

*Density values are approximate. Actual density varies according to resin grade, fillers, reinforcement, additives, and product construction.

Density is particularly useful in recycling because it allows certain plastics to be separated using 침강-부유 분리. However, density separation alone cannot distinguish every polymer.

For example, both PP and most PE grades have densities below water and therefore normally float in a standard water tank.

#1 PET — Polyethylene Terephthalate

PET, also written as PETE, is one of the most widely recycled plastics.

Common PET Products

PET is commonly found in:

Water bottles
Soft drink bottles
Cooking oil bottles
Food jars
PET trays
Polyester fibers and textiles
PET strapping

PET is strong, lightweight, transparent, and has excellent barrier properties, making it particularly suitable for beverage and food packaging.

PET Density and Separation

Typical PET density is approximately 1.34–1.39 g/cm³, meaning PET normally sinks in water.

This property is extremely useful during bottle recycling.

After PET bottles are crushed into flakes, a sink-float separation tank can help separate:

PET flakes — sink
PP caps — float
HDPE caps — float

This allows a relatively simple density-separation stage to remove much of the PP and PE contamination from PET flakes.

PET Recycling Process

A typical PET bottle recycling process may include:

Debaling → sorting → label removal → crushing → sink-float separation → hot washing → friction washing → rinsing → dewatering → drying → flake sorting

Clean PET flakes can then be used for applications including polyester fiber, strapping, sheet extrusion, or further pelletizing.

For large-scale post-consumer bottle recycling, a complete 페트병 재활용 시스템 combines sorting, size reduction, washing, density separation, and drying into a continuous process.

Main PET Recycling Challenges

Common contaminants include:

PVC
PP and PE caps
라벨
Adhesives
Food and beverage residue
궤조
Colored PET
Other polymers

PVC contamination is particularly undesirable in PET recycling because PET and PVC have different thermal characteristics and must be carefully separated before high-quality reprocessing.

#2 HDPE — High-Density Polyethylene

HDPE is one of the most common rigid plastics used in consumer packaging and industrial applications.

Common HDPE Products

Typical HDPE waste includes:

Milk bottles
Detergent bottles
Shampoo bottles
Chemical containers
Jerry cans
Industrial drums
Plastic crates
팔레트
Waste bins
HDPE pipes

HDPE combines toughness, chemical resistance, impact resistance, and relatively low density.

HDPE Density and Separation

Typical HDPE density is around 0.94–0.97 g/cm³, so unfilled HDPE normally floats in water.

This makes water-based density separation useful when HDPE is mixed with heavier plastics such as PET or PVC.

However, fillers and additives can change the density of a finished HDPE product.

HDPE Recycling Process

Rigid HDPE recycling commonly involves:

Sorting → shredding or crushing → washing → friction cleaning → sink-float separation → dewatering → drying → pelletizing

Large products such as drums, thick containers, pallets, lumps, and pipes may require primary size reduction before granulation.

ㅏ 고강도 플라스틱 분쇄기 or rigid-plastic shredder can be used for thick-walled material, while long HDPE pipes often require a dedicated pipe shredding system.

For contaminated post-consumer rigid plastic, a Rigid Plastic Washing Line for PP, HDPE and PVC can integrate size reduction, washing, separation, and drying.

Main HDPE Recycling Challenges

Typical issues include:

Paper and film labels
Adhesive
Oil
Chemicals
Metal components
Different colors
PP contamination
Mineral-filled plastics

The required equipment therefore depends heavily on whether the feedstock consists of clean industrial scrap or contaminated post-consumer material.

#3 PVC — Polyvinyl Chloride

PVC is a versatile plastic used extensively in construction, infrastructure, flooring, electrical products, and industrial applications.

It exists in both rigid PVC 그리고 flexible PVC forms.

Common PVC Products

Typical PVC waste includes:

Water and drainage pipes
Window profiles
Door profiles
Wall panels
바닥
Cable insulation
Vinyl sheets
Flexible hoses
Medical products

Why PVC Recycling Is Different

PVC contains chlorine as part of its polymer structure and may also contain significant quantities of additives such as:

Plasticizers
Stabilizers
Fillers
Pigments
Impact modifiers

Different PVC formulations can therefore behave very differently during recycling.

Clean production scrap from PVC pipe or profile manufacturing is generally much easier to recycle than mixed post-consumer flexible PVC waste.

PVC Density

PVC usually has a density above 1.0 g/cm³ and therefore normally sinks in water.

Its actual density varies considerably depending on additives and fillers.

PVC Recycling Process

Clean rigid PVC scrap may be processed through:

Sorting → crushing → metal removal → fine grinding if required → classification → re-extrusion

Long PVC pipes and profiles present a feeding challenge for conventional crushers. A dedicated Crusher for PVC Pipe & Profiles allows long material to be fed horizontally for controlled size reduction.

Some PVC applications also require the crushed material to be reduced further into fine powder using a pulverizer.

Main PVC Recycling Challenges

The key challenge is maintaining a consistent PVC stream.

Mixing PVC with polymers such as PET, PE, or PP can reduce the quality of the recovered material and create processing problems downstream.

For this reason, effective polymer identification and sorting are especially important when processing mixed plastic waste.

#4 LDPE — Low-Density Polyethylene

LDPE is a flexible polyethylene widely used in packaging film.

Unlike rigid HDPE containers, LDPE waste is often thin, lightweight, dirty, and difficult to feed consistently into recycling machinery.

Common LDPE Products

LDPE and related flexible PE materials are commonly found in:

Shopping bags
Packaging film
스트레치 필름
Shrink film
농업 필름
Greenhouse film
Bubble wrap
Flexible packaging
Industrial film scrap

LDPE Density

Typical LDPE density is approximately 0.91–0.94 g/cm³, so it normally floats in water.

Why Film Recycling Is Challenging

Flexible plastic film creates several processing problems:

Very low bulk density
High moisture after washing
Dirt and sand contamination
Difficult continuous feeding
Film wrapping around rotating components
High transportation volume
Inconsistent material flow

Agricultural film may contain particularly high levels of soil, sand, organic matter, and moisture.

LDPE Film Recycling Process

A typical process is:

Sorting → shredding → washing → friction washing → float separation → dewatering → squeezing/drying → densifying → pelletizing

For heavily contaminated flexible waste, a dedicated PP/PE 필름 재활용 빨래 건조대 is normally more suitable than machinery designed for rigid plastics.

After washing, a film squeezer or densifier can reduce moisture and increase bulk density before extrusion.

#5 PP — Polypropylene

Polypropylene is another major recyclable thermoplastic and is widely used in both rigid and flexible products.

Common PP Products

Typical applications include:

Bottle caps
식품용기
Buckets
Crates
Automotive components
Battery cases
Household products
PP 짠 가방
FIBC jumbo bags
Raffia
Non-woven fabric
사출 성형 스크랩

PP Density

PP has one of the lowest densities among common plastics, typically around 0.89–0.92 g/cm³.

It therefore normally floats in water.

Can PP and PE Be Separated With Water?

Not reliably using ordinary water alone.

Both PP and most PE grades have densities below 1.0 g/cm³ and therefore tend to float in a standard sink-float tank.

This means that a simple water tank is highly effective for separating PP/PE from heavier polymers such as PET or PVC, but usually cannot provide precise PP-versus-PE separation.

When PP and PE must be separated from each other, additional techniques may be required depending on material condition and purity requirements.

PP Recycling Process

For rigid PP:

Sorting → shredding/crushing → washing → separation → drying → pelletizing

For PP woven bags or flexible materials:

Shredding → washing → friction cleaning → dewatering → squeezing/densifying → pelletizing

Clean PP production scrap may require only size reduction and extrusion, while contaminated post-consumer PP requires a more complete washing system.

#6 PS — Polystyrene

Polystyrene is often associated with foam packaging, but not all PS is foam.

Common forms include:

General-purpose polystyrene (GPPS)
High-impact polystyrene (HIPS)
Expanded polystyrene (EPS)
Extruded polystyrene (XPS)

Common PS Products

Applications include:

Rigid food trays
Disposable products
HIPS housings
Appliance components
Refrigerator liners
Protective packaging
EPS foam boxes
Insulation materials

PS Density

Solid PS resin typically has a density slightly above water and therefore generally sinks.

Foamed products such as EPS behave differently because their structure contains a large volume of air, giving the finished product a very low apparent bulk density.

Why EPS Recycling Is Different

EPS is extremely lightweight and bulky.

Transporting untreated EPS waste can therefore be inefficient because a truck or container may reach its volume limit long before reaching its weight capacity.

EPS recycling frequently includes a volume-reduction stage such as:

Crushing → compacting or hot melting → pelletizing

Densification greatly reduces storage and transportation volume before further processing.

Main PS Recycling Challenges

Challenges may include:

Low bulk density
Food contamination
Mixed grades
Flame retardants in some applications
Other polymer contamination
Difficult collection economics

Clean industrial PS or HIPS scrap can nevertheless be mechanically recycled when properly identified and separated.

#7 OTHER — ABS, PC, PA, PMMA, PLA and Other Plastics

Code 7 is often misunderstood.

It does not mean that the plastic is automatically a mixed material or that it cannot be recycled.

Instead, Code 7 acts as a broad category for plastics that do not fall under Codes 1 through 6.

Examples of Code 7 Plastics

Depending on the product and coding system, this category can include:

ABS — Acrylonitrile Butadiene Styrene
PC — Polycarbonate
PA — Polyamide / Nylon
PMMA — Acrylic
PLA — Polylactic Acid
Various engineering plastics
Multilayer structures
Certain polymer blends

These materials have very different properties and therefore cannot be treated as one recycling stream.

Can Code 7 Plastic Be Recycled?

Sometimes, yes.

A clean and well-sorted stream of industrial ABS, PC, PA, or PMMA scrap may be suitable for mechanical recycling.

The difficulty occurs when different Code 7 polymers are mixed together or when the exact resin composition is unknown.

For engineering plastics, accurate identification may require more sophisticated sorting or analytical methods before shredding, separation, and extrusion.

How Are Different Plastics Identified in a Recycling Plant?

Resin codes are useful when they are visible, but industrial recycling plants cannot rely entirely on printed numbers.

Labels may be missing, products may be broken, and industrial scrap may never have carried a resin identification symbol.

Several identification and separation methods are therefore commonly used.

1. Resin Identification Codes

RIC markings provide a quick initial indication of polymer type.

They are particularly useful for manually identifying intact packaging and molded products.

However, they should not be treated as a complete sorting solution.

2. Visual and Manual Sorting

Experienced operators can often identify materials using characteristics such as:

Product type
Color
Rigidity
투명도
Surface appearance
типичное применение

Manual sorting is simple but becomes less practical at high throughput or when visually similar polymers are mixed.

3. Density and Sink-Float Separation

Density separation is one of the most widely used techniques in plastic recycling.

In a standard water-based sink-float tank:

PP usually floats
LDPE usually floats
HDPE usually floats
PET usually sinks
PVC usually sinks
Solid PS usually sinks

This makes sink-float separation especially useful in applications such as PET bottle recycling, where PET flakes can be separated from floating PP and PE caps.

However, density can be changed by fillers, additives, reinforcements, foaming, or multilayer construction.

ㅏ 싱크-플로트 분리 탱크 should therefore be considered one part of a complete sorting process rather than a universal polymer separator.

4. NIR Optical Sorting

Near-infrared, or NIR, sorting systems analyze reflected light to identify many different polymer types automatically.

NIR technology is widely used in high-throughput sorting operations.

However, performance depends on factors such as:

Surface condition
Material color
오염
Product geometry
Sensor configuration

Conventional NIR systems may also have difficulty identifying some carbon-black plastics.

5. FTIR Analysis

Fourier-transform infrared spectroscopy, or FTIR, can be used to identify unknown polymers by analyzing their infrared absorption spectrum.

FTIR is particularly useful for:

Laboratory analysis
Material verification
Unknown industrial scrap
Quality control

It is generally an identification tool rather than a bulk mechanical separation process.

6. Electrostatic Separation

After plastics have been properly size-reduced, cleaned, and dried, electrostatic separation can be used in certain applications to separate mixed polymer flakes according to differences in electrical behavior.

The suitability of the process depends strongly on:

Polymer combination
Particle size
습도
Surface cleanliness
Material composition

Material testing is normally recommended before selecting an electrostatic separation system.

Why Correct Plastic Separation Matters

A recycling line does more than make plastic smaller.

The objective is to produce a recycled material with sufficiently consistent purity, moisture level, particle size, and composition for its intended downstream application.

Poor polymer separation can cause:

Unstable extrusion
Reduced mechanical properties
Surface defects
Color inconsistency
Filter blockage
Excessive reject rates
Lower recycled material value

The required purity depends on the final product.

A recycling plant producing low-grade molded products may tolerate more contamination than a plant producing high-quality pellets, sheets, fibers, or bottle-grade material.

For this reason, the correct recycling process should always be designed around both the feedstock 및 required final product.

Typical Recycling Process by Plastic Type

플라스틱	Typical Recycling Route
PET 병	Sorting → label removal → crushing → density separation → hot washing → drying
HDPE bottles	Sorting → crushing → washing → density separation → drying → pelletizing
HDPE drums/crates	Shredding → crushing → washing → drying → pelletizing
PVC pipes/profiles	Crushing → metal removal → grinding/pulverizing → reprocessing
LDPE film	Shredding → washing → dewatering → squeezing/densifying → pelletizing
PP rigid plastic	Crushing → washing → separation → drying → pelletizing
PP 짠 가방	Shredding → washing → squeezing/densifying → pelletizing
EPS	Crushing → densifying/compacting → pelletizing
ABS/PC/PA/PMMA	Identification → sorting → shredding/crushing → separation as required → extrusion

There is no single plastic recycling machine that is ideal for every feedstock.

How to Choose the Right Plastic Recycling Equipment

Before selecting a shredder, crusher, washing line, separation system, or pelletizer, several factors should be evaluated.

플라스틱 종류

Determine whether the material is:

애완 동물
HDPE
LDPE
PP
PVC
추신
ABS
PC
아빠
PMMA
Mixed plastic

Whenever possible, avoid designing a recycling process around unidentified mixed material.

Material Form

The same polymer may require completely different equipment depending on its physical form.

For example, HDPE may arrive as:

병
Drums
Crates
팔레트
Large lumps
Pipes

LDPE may arrive as:

Loose film
Baled film
농업 필름
스트레치 필름
Production edge trim

Material dimensions, wall thickness, bulk density, and feeding behavior directly affect machine selection.

오염

Determine whether the material contains:

Dirt
Sand
Paper
라벨
Adhesive
Oil
Food
Metal
유리
목재
Other plastics

Clean factory scrap may require only crushing and pelletizing, while heavily contaminated post-consumer waste may require a complete washing and separation line.

Required Final Product

The recycling process should be designed around the desired output:

Shredded pieces
깨끗한 플레이크
Regrind
Fine powder
고밀도 소재
Recycled pellets

Equipment that is suitable for producing 20–50 mm shredded material is very different from a system designed to produce clean extrusion-grade pellets.

용량

Specify the required production capacity in kg/h or tonnes/h.

Throughput affects:

Machine size
모터 파워
Conveyor dimensions
Washing tank dimensions
Dryer capacity
Extruder size
Factory layout
Utility requirements

Utilities and Site Conditions

A complete recycling project should also consider:

전압
빈도
Three-phase power availability
Water supply
Wastewater treatment
압축공기
Heating requirements
Available floor space
Ceiling height
Material storage

Evaluating these factors before equipment selection can prevent expensive modifications later.

Frequently Asked Questions About Plastic Recycling Codes

What do the numbers 1 through 7 on plastic mean?

They are Resin Identification Codes used to identify the primary plastic resin. Codes 1–6 represent several major resin families, while Code 7 covers other plastics outside those categories.

Does a recycling number mean the plastic is recyclable?

No. A resin identification number identifies the material; it does not guarantee that a collection or recycling system exists for that particular product.

Recyclability depends on the polymer, product design, contamination, regional collection infrastructure, and available processing technology.

Which plastic types float in water?

Unfilled PP, LDPE, and HDPE normally float because their densities are generally below 1.0 g/cm³.

PET, PVC, and solid PS generally sink.

Fillers, additives, foaming, and composite construction can change this behavior.

Can PP and PE be separated using a normal sink-float tank?

Not effectively in most cases because both PP and common PE grades normally float in water.

A standard water-based sink-float tank is more effective for separating floating PP/PE from heavier materials such as PET or PVC.

Which plastics are easiest to recycle?

Clean, single-polymer streams of PET, HDPE, PP, and PE are widely processed through mechanical recycling.

However, the condition of the material can be more important than the resin code alone. Clean industrial PP scrap may be much easier to recycle than heavily contaminated post-consumer PET, for example.

Is Code 7 plastic recyclable?

Some Code 7 plastics are recyclable.

Clean ABS, PC, PA, PMMA, and other engineering-plastic production scrap can often be mechanically recycled if the polymer is correctly identified and kept separate.

Mixed, multilayer, or unidentified Code 7 material is considerably more difficult to process.

Why is PVC contamination a concern in PET recycling?

PVC and PET have different processing characteristics. PVC contamination can negatively affect PET reprocessing and final product quality, making effective sorting important in high-purity PET recycling.

What machines are used for plastic recycling?

Depending on the feedstock, a recycling line may include:

Conveyor
파쇄기
Plastic crushers or granulators
Trommel screens
Magnetic separators
Friction washers
Hot washing systems
Sink-float tanks
Dewatering machines
Thermal dryers
Film squeezers
밀도제
Optical or electrostatic separators
Pelletizing systems

The correct configuration depends on the plastic type, contamination, required capacity, and target final product.

From Plastic Identification to a Complete Recycling Process

Understanding plastic recycling codes is a useful starting point, but industrial recycling requires more than simply identifying a number on a product.

Polymer type, density, contamination, physical form, particle size, moisture, and final purity requirements all influence how a recycling line should be designed.

A PET bottle recycling plant may rely heavily on density separation and hot washing. An LDPE film plant needs efficient washing, dewatering, and densification. Long PVC or HDPE pipes require specialized size-reduction equipment. Mixed engineering plastics may require advanced identification and separation before extrusion.

At Rumtoo, we design and manufacture plastic recycling equipment for a wide range of rigid and flexible plastic applications, including plastic shredders, crushers, washing lines, sink-float separation systems, drying equipment, and pelletizing lines.

If you are planning a recycling project, provide the plastic type, material photos, maximum dimensions, contamination level, required output size, target capacity, and local voltage/frequency. Based on this information, the recycling process and equipment configuration can be matched to the actual feedstock rather than relying on a one-size-fits-all solution.

플라스틱 재활용 코드 1–7: 플라스틱 유형 완전 가이드