GB2575234A

GB2575234A - Method for producing polystyrene beads

Info

Publication number: GB2575234A
Application number: GB1807420.3A
Authority: GB
Inventors: Dolder Mark
Original assignee: Bgrp Holdings Ltd
Current assignee: Bgrp Holdings Ltd
Priority date: 2018-05-04
Filing date: 2018-05-04
Publication date: 2020-01-08
Anticipated expiration: 2038-05-04
Also published as: GB201807420D0; GB2575234B

Abstract

A method of manufacturing expanded polystyrene beads comprising [a] providing polystyrene coated with an expanding agent, such as pentane; [b] feeding the polystyrene into an expansion chamber 107 and agitating under pressure to produce initial expanded polystyrene beads; [c] passing the expanded beads over a drying bed 109 and into storage silo 111; [d] holding the expanded polystyrene beads in the storage silo 111 for a predetermined time; and [e] and after the predetermined time feeding the initial expanded polystyrene into the expansion chamber 107 and agitating under pressure and passing the expanded beads over the drying bed 109 to produce expanded polystyrene beads preferably with a density of 8.5-11.5 kg/m3. Also disclosed is an apparatus for manufacturing the expanded polystyrene beads.

Description

METHOD FOR PRODUCING POLYSTYRENE BEADS

Field of Invention

The present invention relates to a method of producing expanded polystyrene beads specifically for soft furnishing usage. The invention further relates to expanded polystyrene beads manufactured according to the method, soft furnishing products filled with such expanded polystyrene beads and to the apparatus for use in such a method.

Background of the Invention

The conventional filling for beanbags is expanded polystyrene bead. The process for expansion requires a bespoke chemical plant that applies steam, under pressure, to a raw material resembling a grain of sugar causing it to expand, resulting in a polystyrene bead or “bean” that has many commercial uses.

Beanbag manufacturers have traditionally bought bead from companies that produce expanded polystyrene to be moulded to form insulation products for the construction, caravan and boat markets. The process of producing expanded polystyrene for block moulding applications is well established, but the product it produces is suboptimal for beanbags as the size, shape, density and other properties are not designed for this end use. Typically the density of the expanded polystyrene beads used in moulding applications is 12 kg/m³ to 14 kg/m³.

In particular, many grades of raw material are designed to stick together when expanded as they are then moulded into finished goods which means they will not move independently inside a beanbag to produce the required level of comfort. Also, bead that is produced in one place and then transported in loose form to another, is drawn through powerful impeller fans causing distortion and damage to the bead resulting in some beads becoming elliptical and or flattened.

This present invention aims to provide a method of manufacturing an expanded polystyrene bead that is optimal for soft furnishings usage.

Summary of the Invention

According to a first aspect of the present invention, there is provided a method of manufacturing expanded polystyrene beads comprising:

a) providing a polystyrene raw material coated with at least an expanding agent;

b) feeding the polystyrene raw material into an expansion chamber via loading means and subjecting said polystyrene raw material to agitation under pressure to produce initial expanded polystyrene beads;

c) passing the initial expanded polystyrene beads over a drying bed and into a storage silo;

d) holding said initial expanded polystyrene beads in said storage silo for a pre-determined time; and

e) after the pre-determined time, feeding said initial expanded polystyrene beads back into the expansion chamber via loading means to subject said initial expanded polystyrene beads to agitation under pressure and passing over the drying bed to produce the expanded polystyrene beads wherein one or more of the conditions selected from pressure, humidity, temperature or loading means speed are controlled to achieve an expanded polystyrene bead density in the range of from 8.5 kg/m³ to 11.5 kg/m³.

The two stage expansion method of the present invention provides an advantage that the resulting expanded polystyrene bead is optimal for soft furnishings usage, in particular for bean bags. This is because the method sets the optimal bead size, shape and density and the resulting bead is resilient to deformation in use and free flowing.

It is believed that the first expansion step initiates the expansion process and subsequent optional holding time allows the beads to absorb air. The second expansion step completes expansion and, again, the subsequent holding time leads to further expansion by taking up air as well as setting the bead shape, allowing it to be compressed and regain its form.

The method of the present invention avoids over-processing of the expanding agent (e.g. pentane), which will result in the expanded polystyrene beads collapsing, and prevents pitting of the beads caused by too high a steam pressure.

In particular, it has been recognised in the present invention that by controlling one or more of the conditions of pressure, temperature, humidity or loading means speed, the final density, shape and resistance of the expanded polystyrene bead can be optimised for use in the soft furnishing industry. The resulting bead is suitably shaped, is sufficiently resistant to deformation in use and does not stick to other beads. In particular, the bead is resistant to deformation where the bead is pushed through the system by air (as discussed in greater detail below) and not pulled using a propeller system.

Theone or more conditions of pressure, temperature, humidity and loading means speed may be controlled with respect to the expansion chamber. Alternatively, the one or more conditions of pressure, temperature, humidity and loading means speed may be controlled throughout the system comprising the expansion chamber, drying bed and the storage silo.

In one embodiment, the method is a continuous method.

The method may be carried out in a 12 hour period, preferably within an 8 hour period. This provides a much more time effective method than the known methods of forming polystyrene beads for the packaging industry.

In a preferred embodiment, the expanding agent on the polystyrene raw material is pentane. The polystyrene raw material may also be coated with an antistatic agent and/or flame retardant agent. This antistatic agent serves to prevent the polystyrene beads from sticking together during formation of the initial expanded polystyrene beads or the expanded polystyrene beads. The flame retardant agent may be included for safety considerations, as will be appreciated in the art. For example, the polystyrene raw material may be Styropor® (BASF) or Sunpor®.

In one embodiment, the method is carried out in a controlled temperature and humidity environment.

The expansion chamber may preheated to a temperature greater than 50°C prior to step b) and step e) for example from 60°C to 70°C. The expansion chamber may be preheated with steam.

In one embodiment, steam preheats and applies pressure to the expansion chamber. Optionally, the steam is supplied to the expansion chamber via pipework comprising a valve. The valve may comprise a notched key having settings from 1 to 11 wherein 1 is shut and 11 is fully open. In such embodiments, the valve may be set at from 6 to 11 in step b) and step e), preferably 8 or 9 in step b) and preferably 9 or 10 in step e).

The expansion chamber may comprise an agitator. The agitator may have a fixed speed.

The loading means speed in step b) may be from 60% to 95%, preferably from 70% to 80% and more preferably 75%. Further, the loading means speed in step e) may be from 60% to 100%, preferably from 75% to 90% and more preferably 85%.

In some embodiments, loading means comprises one or more loading augers. Loading means may comprise a single loading auger for feeding the polystyrene raw material into the expansion chamber in step b) and feeding the initial expanded polystyrene beads into the expansion chamber in step e). However, preferably loading means comprises a first loading auger for feeding the polystyrene raw material into the expansion chamber in step b) and a second loading auger for feeding the initial expanded polystyrene beads into the expansion chamber in step e).

Humidity may be controlled via the use of one or more heaters. The heaters may be located at various points throughout the system to ensure that the humidity is consistent despite environmental conditions to prevent or at least limit any detrimental effect on the final density of the expanded polystyrene beads.

The drying bed may have an operating temperature of between 14°C and 19°C, which may vary at the entry and exit points and in the main part of drying bed. As will be appreciated, the main (middle) part of the drying bed may have the highest operating temperature. The operating temperature of the drying bed may kept constant by the presence of one or more infrared heaters.

Movement of the initial expanded polystyrene beads and movement of the expanded polystyrene beads may be affected via one or more blowers. The blowers may be located a various points throughout the system to ensure effective movement of the beads throughout the apparatus.

The pre-determined time during which the initial expanded polystyrene beads are held in the storage silo may be from 30 minutes to 4 hours, preferably from 1 to 3 hours, more preferably two hours.

The expanded polystyrene bead density formed by the method of the present invention is preferably less than11.0 kg/m³, more preferably less than 10.5 kg/m³.

In one embodiment, the density of the initial polystyrene bead and/or the expanded polystyrene bead is monitored at intervals throughout the method. In particular, a set volume of initial polystyrene bead and/or the expanded polystyrene bead may be extracted and weighed to determine the density via calculations well known in the art to ensure that the density is within at least the range of from 8.5 kg/m³ to 11.5 kg/m³, preferably less than 11.0 kg/m³ and more preferably less than 10.5 kg/m³.

In some embodiments of the present invention, the pressure, temperature, humidity and loading means speed) may all be controlled throughout the method.

The method may further comprise the step of moving the expanded polystyrene beads in to a storage silo and holding the expanded polystyrene beads in said storage silo for a predetermined time, wherein the predetermined time may be overnight. Further, the method may comprise the step of moving the expanded polystyrene beads to a further location for filling a soft furnishing product after the predetermined time.

The method of the present invention may be carried out at a single site.

According to a second aspect of the present invention, there is provided expanded polystyrene beads manufactured according to the method of the first aspect having a final density of from in the range of from 8.5 kg/m³ to 11.5 kg/m³, preferably less than 11.0 kg/m³ and more preferably less than 10.5 kg/m³.

According to a third aspect of the present invention, there is provided a soft furnishing product filled with a plurality of expanded polystyrene beads of the second aspect. In one embodiment, the soft furnishing product is a bean bag.

According to a fourth aspect of the present invention, there is provided apparatus for manufacturing expanded polystyrene beads comprising:

a steam generator;

loading means;

an expansion chamber comprising an agitator;

a drying bed;

one or more storage silos; and one or more heaters.

In some embodiments, the loading means comprises a first loading auger and a second loading auger. The expansion chamber may comprise at least a first inlet and a second inlet for receiving material fed into the expansion chamber via the first loading auger and the second loading auger respectively.

The apparatus may further comprise transfer tubes, wherein the transfer tubes connect the expansion chamber to the drying bed, the drying bed to the one or more storage silos and the one or more storage silos to the expansion chamber.

Further, the apparatus may comprise one or more blowers to affect movement through the transfer tubes.

In one embodiment of the present invention, the steam generator is connected to the expansion chamber via pipework comprising a valve and the valve may comprise a notched key having settings from 1 to 11 wherein 1 is shut and 11 is fully open.

Features of the first aspect of the present invention apply mutatis mutandis to the second, third and fourth embodiments of the invention.

Detailed Description

Embodiments of the present invention will now be described with reference to the following, non-limiting examples and figures.

Figure 1 shows an overview of apparatus in accordance with one embodiment of the present invention;

Figure 2 shows an enlarged view of the feeding system for the expansion chamber of the first expansion pass; and

Figure 3 shows an enlarged view of the feeding system for the expansion chamber of the second expansion pass and the drying bed.

As illustrated in Figures 1 to 3, apparatus 101 for manufacturing expanded polystyrene beads in accordance with one embodiment of the present invention comprises a compressor, a steam generator, loading hopper 105 comprising first loading auger, an expansion chamber 107, a drying bed 109, holding silos 111, a second expansion hopper 103, charging hopper 113 comprising second loading auger, transfer tubes 115 and blowers 117. The apparatus further comprises infrared heaters and extraction fans to control the temperature and humidity of the surrounding environment and so optimise the expanded polystyrene bead formation.

The steam generator comprises a water tank, water treatment means and a heater. The water in the water tank is softened with water softeners, such as RODOL L7 to avoid mineral deposits in the pipes leading to reduced efficiency, damage and failure of the system. Further the water is treated with a pH adjusting agent and rust inhibitors, such as RODOL Brinetabs (100% salt) to avoid damaging the apparatus or the efficiency. The water in the water tank is heated by the heater to produce steam which is fed through pipes to the expansion chamber 107.

The loading hopper 105 comprises an inlet for receiving raw material polystyrene beads and an outlet for feeding the raw material polystyrene beads into the expansion chamber 107 via transfer tubes 115 and first loading auger for controlling the speed at which the raw material polystyrene beads are fed into the expansion chamber 107.

The expansion chamber 107 is supplied with steam from the steam generator via pipework. The expansion chamber 107 comprises an agitator. The agitator speed is fixed, i.e. substantially constant, during each expansion pass but a torque sensor is fitted to the agitator to ensure that any increase in torque caused by the raw material or the first loading auger speed being out of specification for the particular raw material sets off an alarm and the machine will vent instantly. In this embodiment, the expansion chamber 107 is 5 metres in height. The expansion chamber 107 comprises a first inlet 119 proximate to the base for receiving the raw material polystyrene beads for a first expansion run and a second inlet 121 proximate to the base on the opposite side to the first inlet for receiving the initial expanded polystyrene beads for a second expansion run. The first and second inlets are provided with gates to enable closures of each during the respective expansion runs. The expansion chamber 107 further comprises an outlet proximate to the drying bed 109 through which the initial expanded polystyrene beads and the expanded polystyrene beads exit and feed into the drying bed 109.

The drying bed 109 comprises an inlet for receiving the initial expanded polystyrene beads and the expanded polystyrene beads at the end proximate to the expansion chamber 107, and an outlet at the opposite end, through which the initial expanded polystyrene beads and the expanded polystyrene beads exit the drying bed 109 via transfer tubes 115 and are fed into storage silos 111. The drying bed 109 comprises one or more infrared heater, such as Claudgen HE8530 Ceramiczone 3kw heaters, and an extraction fan.

Storage silos 111 comprise an inlet at the upper surface thereof, through which the initial expanded polystyrene beads or the expanded polystyrene beads are fed into the storage silos 111 via transfer tubes 115 and an outlet at the lower surface thereof through which initial expanded polystyrene beads exit the storage silos 111 for transfer to the second expansion hopper 103 or the expanded polystyrene beads exit for transfer to an external filling station (not shown) for end use via transfer tubes 115.

The second expansion hopper 103 comprises an inlet 123 in the upper surface thereof to receive the initial expanded polystyrene beads fed from the storage silos 111 via transfer tubes 115 and an outlet 125 in the lower surface thereof to fed the charging hopper 113 comprising the second loading auger. The charging hopper 113 (comprising a similar inlet and outlet) which subsequently feeds the initial expanded polystyrene beads back into the expansion chamber 107 via transfer tubes 115 and the second inlet 121 of the expansion chamber 107. The speed at which the initial expanded polystyrene beads are fed back into the expansion chamber is controlled by second loading auger.

The apparatus further comprises blowers 117 for advancing the initial expanded polystyrene beads and the expanded polystyrene beads through the transfer tubes 115 and through the drying bed 109. The blowers 117 are positioned throughout the apparatus to ensure that the initial expanded polystyrene beads and the expanded polystyrene beads move effectively through the apparatus, as will be readily appreciated by the person skilled in the art. Further, blowers 117 avoid damage to the polystyrene beads which may otherwise occur when the polystyrene beads are pulled via a propeller system, as is typically employed in the art. In addition the pipework supplying steam from the steam generator to the expansion chamber 107 comprise a valve for controlling the amount of steam passing into the expansion chamber 107 and safety air valves, as described in greater detail below.

The following exemplary methodology for manufacturing expanded polystyrene beads using the above described apparatus was followed:

1st expansion • Turn compressor on. The compressor creates the maximum air pressure available throughout the system but is controlled by a pressure valve to the apparatus, as described below.

• Allow the steam generator to reach an operating pressure of between 6 to 8 bar.

• Load octabin with polystyrene raw material onto the loading hopper.

• Slowly open steam valve % turn, allowing the steam to heat the system and the pipes, at the same time switch on expansion chamber, check the steam temperature and open safety air valve.

• Set the first loading auger speed in the loading hopper to 70% to 75% of full power.

• Select an empty storage silo to receive initial expanded polystyrene beads of 1^st expansion run.

• Wait until water in storage tank in boiler room is at 45°C or red cylinder on expansion chamber is hot if water already up to temperature.

• Slowly open boiler steam valve fully.

• Turn on extraction fans.

• As this is a 1^st expansion run, make sure the 2^nd expansion gate is closed to stop bead escaping past the gate, steam valve on expansion chamber is set to fully open (until the chamber is at an operating temperature of at least 60°C), 1^st expansion gate is open and safety air valve open.

• Drying bed fan set to fully open.

• Once the temperature of the expansion chamber is up to between 55°C and 65°C, preferably 62°C, set expansion chamber steam valve to desired setting (7.5 to 8), and turn the first loading auger on.

• Begin loading polystyrene raw material into expansion chamber from the octabin.

• The polystyrene raw material undergo initial expansion in the expansion chamber to form initial expanded polystyrene beads and rise to the top of the expansion chamber where they will exit the chamber into the transfer tubes leading to the drying bed. The initial expanded polystyrene beads enter an airflow generated by blowers to advance the initial expanded polystyrene beads over the drying bed.

• Once a good flow of beads passing through the drying bed is achieved, the first loading auger speed is raised to approximately 85% and the air supply from the blower directing the beads over the drying bed is decreased.

• The density and quality of the bead is checked at regular intervals to ensure there are no collapsed beads. This check is carried out by monitoring the weight of a set volume of beads and converting the weight to density (g/l) using conventional equations. If collapsed beads are detected then the first loading auger speed is slowly adjusted, generally increased.

• The expansion chamber steam valve is held at the desired level (which depends upon the starting material) throughout the 1^st pass.

• Once the initial expanded polystyrene beads have passed over the drying bed, the continuing airflow (provided by one or more blowers) advances the beads to the storage silo.

The initial expanded polystyrene beads are held in the storage silo for two to four hours before undergoing a second expansion run as follows.

2nd expansion • Turn compressor on.

• Slowly open steam valve % turn, allowing the steam to heat the system and the pipes, at the same time switch on the expansion chamber and check the steam temperature in the system. Open safety air valve.

• Select an empty storage silo to receive expanded polystyrene beads of 2nd expansion run, ensuring there is room in another storage silo to take overflow.

• Wait until water in storage tank is at 45°C or red cylinder on expansion chamber is hot if water already up to temperature.

• Slowly open boiler steam valve fully.

• Turn on extraction fans.

• Although this is a 2nd expansion guide, make sure the 2^nd expansion gate is closed (this prevents steam leaking back into the 2^nd loading auger and storage silo which causes blockages) to stop beads escaping past the gate, steam valve on expansion chamber is set to fully open (until the chamber is at operating temperature of 60°C+), 1^st expansion gate is closed and safety air valve open.

• Drying bed fan should be set to fully open.

• Set the second loading auger speed at desired level, generally 85% for 2nd expansion.

• Once chamber is up to temperature (approx. 60°C), set expansion chamber steam valve to desired setting (usually 8 or 9), open the 2^nd expansion gate and turn the second loading auger on.

• Begin feeding initial expanded polystyrene beads from the storage silo through the transfer tubes to the expansion chamber.

• The initial expanded polystyrene beads are subjected to agitation under pressure in the expansion chamber to form the final expanded polystyrene beads product, rising to the top of the expansion chamber where they exit the chamber into transfer tubes leading to the drying bed. The expanded polystyrene beads enter an airflow generated by blowers to advance the expanded polystyrene beads over the drying bed.

• Once a good flow of beads passing through the drying bed is achieved, the air supply from the blower directing the beads over the drying bed is decreased. The operating speed of the second loading auger is also increased, typically to 95%.

• The density and quality of the bead is checked at regular intervals to ensure there are no collapsed beads, as in the 1^st expansion run, and the sedon loading auger speed is adjusted as required (generally increased).

• The expansion chamber steam valve is held at the desired level (generally 8 or 9) throughout the 2^nd pass.

• Once the expanded polystyrene beads have passed over the drying bed, the continuing airflow (provided by one or more blowers) advances the beads through the transfer tubes to an appropriate storage silo.

Typically the resulting expanded polystyrene beads are held in the storage silo overnight before being transferred via further transfer tubes to a filling station for one or more bead bag products.

Examples

Raw material polystyrene beads were sourced from a number of different manufacturers (as identified in the Table below). The raw polystyrene beads were pre-loaded with pentane which turns to gas on heating to effect expansion of the polystyrene beads. The raw material polystyrene beads were subjected to the above described method of manufacturing expanded polystyrene beads. The exact conditions and resulting densities of each pass are provided in the Tables below.

Table 1 - 1^st Expansion Pass

E □:

bft

Φ CQ

Φ

SP <

C

CO ± u

ehrf efi <y ur?

in H ώ

O

CO £ Φ ώ co

E «! Φ

			m	ΙΓΊ Φ	g	g	Lffl	MO m	kh	57	3
	uh	a	o	o	8		Φ	8	Q	Q	^LJ2
—i	LT)	LF)		Ή	©	«Μ	Φ	©	©
Φ	ch		0-1	Q		ΓΜ	ch	Φ	Q	CN	iH
—1	o		c	Ή	Ή		co		Φ	Ή

Φ

N

Φ

Ώ oo ό co a

ΙΓ) r!

C« iXi

Ch φ

s do ό

Φ ΜΊ flfl iN

Uh

Ldfl

U3

U*l LT)

Μ*ϊ ί/Ί kH biS

Ct

CO ¢0

O

ΤΪ cd

¢8	<sf			«tf 'N
ϊ*ί		v«l	¥-Ί	in
	H	i—1	-—1 $ <7-1 <--l Ί—1

C&

rjq

/)

&

«f i .Γ. ,! i 1-.-1 1—1

CN 3

i—1

φ1 30 1 :

s N ΓΜ

“iB“; 00 :

CM

““£r““ eG rJ

r-4

fN

Cl £

o6

03

η

00

rsi i-1

co 3

Φ 3

ώ

<-

τ? φ φ a. uf?

ψ §

£

Σ3

SU

Φ 4^ 15

1-ΓΊ

Φ ή

m3 oo

CO

LT) uh

CN n uh

Ch ert ιό

ΓΠ φ ςη

Φ e^i

Η ο u_v

Gfl < ca

Φ

oh	efi	efl
MO	to	Ig
Φ	£,·? Ch	£0 Ch
00	00	03
Φ	Φ	a
IN	iN	(N
H	t-l	•i-—4
©	o	©
flfl	flfl	t-fl

O\l ύ&

I'fl <—l

CO kU GO < CD φ

tN ku

Gfl

CD

LO •H

Φ

ΓΝ <N efl --I Φ όη

M3

Ofl r* 1-1 eo i-l Φ eo ί£3 efl

ΓΤι ίΗ Ο η flfl

ΑΊ

Φ

ΑΊ

I'fl f^

CO i--1 a m r^

U3 en efl --i O efl

UO efi

H efl s efl m

£>

Φ

S rn

CN

P

LTj in uh m ί/Ί < CD ’ώ Ή Φ

Gk> Gfl < co go < κα

Ux

GO <

ca kU (Λ < co iZl < CO

Gk> Gfl < CO go < κα

LU

GO κα

LH pl efl eo

S 03 M3' 00 Φ '-H o (N

A

ΓΝ tY?

pl efl

CO

C3 cm

ΓΝ

Φ ςη eo

CM

P σι sfr CO rM P

Φ rJ Φ ΓΝ

N

P

ΟΊ Ό r\l iN

N ¢-1

O eh <N

Φ

B

Φ

ΑΊ N en L’fl in Ϊ-Ί efl CN Φ

Q sx tn

ΑΊ

S’

Ν

IN	F^> •H R	r^ H Φ
tV?	iflT	US' P
p	P
Hi'		<F
N	Ή	Ή

i\l

GS e-M

Φ rXI

P

CO

S

Gfl o rM oeT o co*· ix?

Φ f 1

CO'

CJ co

Φ

0M i^d ?“* £0 on r< e-M

Q N

Λ tn

Table 2 - 2^nd Expansion Pass _>>

£ Φ £3 is co eh i£

I© i0 uh ιϊΊ

Φ ιό ιό «>ί ιό uh eh ιό e*i r\| ιό ιό lCj ί/Ί

φ	iC	L0 i	φ ιό
Cfl		rd:	¢5 <sf
Ct	efl		ι ή
“*i		:	<-4 s-M

φ

Tt ιό ιη ιή

Φ	Φ	Φ
<-M	efl	Ιό
Φ	f·^
i-M		<-4

ΙΪΊ

on	Φ	ιό i	Φ	Φ 10	in
i”h	-4		rd	© <sf	<ef
CM :	eh	Cd :	*4’	Cfl 4si	m
Ή ;		:	^4	<-4 Ή	Ή

ιό s

Φ	Φ i	Φ
CM	^1 :	eh
if	Φ i
	e4	<-4

i-0 *S

O s

ft

> Φ aM ... tft £ cn a	tf d	d i--4	CM Q	MS ' £« : ΪΤΪ d :
ιό	60	r-	φ	Ch Ch :

£ ft φ

N Ch =CMi «Υ

Ο ΐ?Υ <!<

Φ

M3 φ

Φ ί?Υ <3^:

US'

CH οή <hi

Chi

Ο:

φ

Ch

Ο;

ιό

LH

IJJ

U3 ιό Φ ι·ή Ch ζΐή ιό Ch ςη ρ»

LT

; Φ	r-		ΓΝ. j	Cfl : eH rd	tn	ch;	•*4 ^:
: !°h			rT	^{i s}* : Cd	lcT	in ·	u» 5
: rd	N	CM	CM :	rd rj	ή		:

Ch ch

Φ

SP

Ξ5 <

τ? φ φ φ

£2 £

Σ3

ΑΊ p

Φ

Cd

Φ eh c© Φ

Φ <nj rd rs *ί·|·ι·ι □

ft Σ

Uv cfl < co

Φ ku th <£ £33

Φ CM

Φ 4^ ft efl

U3

Ch oo i*^xS rd X3 Q Ch 05 Φ CN όη pv i£> Cfl

P^ i-S efl

Φ eh

Ο\Ι efl

-4 O

ΓΊΊ

US

Ofl r* H m rd ιώ rfl

O Ch p^ l£>

Cfl P^ i-S efl >-4 O efl r» r*

IC.1

CA efl —ΐ Ο m

US efl

H efl

Q

CT5 “2 ιό ΐό φ fh s

CM Φ

ΓΜ

LTi

Φ

Φ i£i

S?

en e4

CM φ

O 05 0 Φ £2

Cfl rM

P

R

N

P

•ax]	·,ν·\| <l	rd		ch
*5f	>'.Ί e.n	>'4	Φ	05
rd	rxl rN	Οζι	m3	Lfl
	Ο Φ	a	Φ	rd
CM	i*M f'M	efl	rfl	ΓΑ
CM	(N CN	rd	CM	CM
Φ	¢3 Q	P	Φ	Φ
hx	hv I'A			ΓΝ
Ή	*“l .---1		-.-4	s-l

Ο

Ο ku (Λ

CO !=© •H Φ ΓΝ

M

Φ ιη

Uk>

1/Ί <

flj

Cfl iZl < κα kU κα o rM kU «Λ <

CO <

Uk>

1/Ί <

Gfl < κα κα

O

0.Ct.

m

S 05 M3' Ο Φ

Φ rd

CC?

efl i\l rd ορ

Π rd m

S’ cm efl

P rd iC?

Φ rd

Φ ί\1

O .CM s σί

Ή Φ rM

Cfl

Φ c J hfl'

Φ

Cfl r\l cM

CM £>

Lh

S

Q .cm

Xf

Cfi

CM

As can be seen from the results provided above, the method and apparatus of the present invention produces expanded polystyrene beads with a density of greater than 8.5kg/m³, approximately 10kg/m³, which has been found to be particularly preferable for use in soft furnishings. Further, the resulting expanded polystyrene 5 beads are well-formed, of regular shape, free flowing and resilient to deformation making them ideal for such soft furnishing usage, for example in bean bags.

Claims

1. A method of manufacturing expanded polystyrene beads comprising:

e) after the pre-determined time, feeding said initial expanded polystyrene beads back into the expansion chamber via loading means to subject said initial expanded polystyrene beads to agitation under pressure and passing over the drying bed to produce the expanded polystyrene beads wherein the one or more of the conditions selected from pressure, humidity, temperature or loading means speed are controlled to achieve an expanded polystyrene bead density in the range of from 8.5 kg/m3 to 11.5 kg/m3.

2. The method of claim 1 wherein the method is a continuous method.

3. The method of claims 1 or 2 wherein the method is carried out in a 12 hour period, preferably within an 8 hour period.

4. The method of any of claims 1 to 3 wherein the expanding agent is pentane.

5. The method of any of claims 1 to 4 wherein the polystyrene raw material is also coated with an antistatic agent and/or a flame retardant agent.

6. The method of any of the preceding claims wherein the method is carried out in a controlled temperature and humidity environment.

7. The method of any of the preceding claims wherein the expansion chamber is preheated to a temperature greater than 50°C prior to step b) and step e).

8. The method of claim 7 wherein the expansion chamber is preheated to a temperature of from 60°C to 70°C.

9. The method of claim 7 or claim 8 wherein the expansion chamber preheated with steam.

10. The method of claim 9 wherein the steam heats and applies pressure to the expansion chamber.

11. The method of claim 9 or claim 10 wherein the steam is supplied to the expansion chamber via pipework comprising a valve.

12. The method of claim 11 wherein in the valve comprises a notched key having settings from 1 to 11 wherein 1 is shut and 11 is fully open.

13. The method of claim 12 wherein the valve is set at from 6 to 11 in step b), preferably 8 or 9.

14. The method of claim 12 or claim 13 wherein the valve is set at from 6 to 11 in step e), preferably 9 or 10.

15. The method of any of the preceding claims wherein the loading means speed in step b) is from 60% to 95%, preferably from 70% to 80% and more preferably 75%.

16. The method of any of the preceding claims wherein the loading means speed in step e) is from 60% to 100%, preferably from 75% to 90% and more preferably 85%.

17. The method of any of the preceding claims wherein loading means comprises:

a first loading auger for feeding the polystyrene raw material into the expansion chamber in step b); and a second loading auger for feeding the initial expanded polystyrene beads into the expansion chamber in step e).

18. The method of any of the preceding claims wherein humidity is controlled via the use of one or more heaters.

19. The method of any of the preceding claims wherein movement of the initial expanded polystyrene beads and movement of the expanded polystyrene beads is affected via one or more blowers.

20. The method of any preceding claim wherein the pre-determined time is from 30 minutes to 4 hours, preferably from 1 to 3 hours, more preferably two hours.

21. The method of any of the preceding claims wherein the expanded polystyrene bead density is less than 11.0 kg/m3, more preferably less than 10.5 kg/m3.

22. The method of any of the preceding claims wherein the expanded polystyrene bead density is monitored at intervals throughout the method.

23. The method of any of the preceding claims wherein pressure, temperature, humidity and agitation are controlled throughout the method.

24. The method of any of the preceding claims further comprising the step of moving the expanded polystyrene beads in to a storage silo and holding the expanded polystyrene beads in said storage silo for a predetermined time.

25. The method of claim 24 wherein the predetermined time is overnight.

26. The method of claim 24 or claim 25 further comprising the step of moving the expanded polystyrene beads to a further location for filling a soft furnishing product after the predetermined time.

27. The method of any of the preceding claims wherein the method is carried out at a single site.

28. Expanded polystyrene beads manufactured according to the method of any of claims 1 to 26 having a final density of from in the range of from 8.5 kg/m3 to 11.5 kg/m3.

29. A soft furnishing product filled with a plurality of expanded polystyrene beads of claim 28.

30. The soft furnishing product of claim 29 wherein the soft furnishing product is a bean bag.

31. Apparatus for manufacturing expanded polystyrene beads comprising:

a steam generator;

loading means;

an expansion chamber comprising an agitator;

a drying bed;

one or more storage silos; and one or more heaters.

32. The apparatus of claim 31 wherein loading means comprises a first loading auger and a second loading auger.

33. The apparatus according to claim 31 wherein the expansion chamber comprises at least a first inlet and a second inlet for receiving material fed into the expansion chamber via the first loading auger and the second loading auger respectively.

34. The apparatus of any of claims 31 to 33 further comprising transfer tubes, wherein the transfer tubes connect the expansion chamber to the drying bed, the drying bed to the one or more storage silos and the one or more storage silos to the expansion chamber.

35. The apparatus of any of claims 31 to 34 further comprising one or more blowers to affect movement through the transfer tubes.

36. The apparatus of any of claims 31 to 35 wherein the steam generator is

5 connected to the expansion chamber via pipework comprising a valve.

37. The apparatus of claim 36 wherein in the valve comprises a notched key having settings from 1 to 11 wherein 1 is shut and 11 is fully open.