GB2030919A – Method of making foam core articles
– Google Patents
GB2030919A – Method of making foam core articles
– Google Patents
Method of making foam core articles
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Info
Publication number
GB2030919A
GB2030919A
GB7928336A
GB7928336A
GB2030919A
GB 2030919 A
GB2030919 A
GB 2030919A
GB 7928336 A
GB7928336 A
GB 7928336A
GB 7928336 A
GB7928336 A
GB 7928336A
GB 2030919 A
GB2030919 A
GB 2030919A
Authority
GB
United Kingdom
Prior art keywords
plastic
core
skin
temperature
manufacturing
Prior art date
1978-08-14
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB7928336A
Other versions
GB2030919B
(en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tri-Seal International Inc
Original Assignee
Tri-Seal International Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1978-08-14
Filing date
1979-08-14
Publication date
1980-04-16
1978-08-14
Priority claimed from US05/933,307
external-priority
patent/US4206165A/en
1979-08-14
Application filed by Tri-Seal International Inc
filed
Critical
Tri-Seal International Inc
1980-04-16
Publication of GB2030919A
publication
Critical
patent/GB2030919A/en
1982-12-15
Application granted
granted
Critical
1982-12-15
Publication of GB2030919B
publication
Critical
patent/GB2030919B/en
Status
Expired
legal-status
Critical
Current
Links
Espacenet
Global Dossier
Discuss
Classifications
B—PERFORMING OPERATIONS; TRANSPORTING
B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
B29C44/20—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of indefinite length
B29C44/22—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of indefinite length consisting of at least two parts of chemically or physically different materials, e.g. having different densities
B—PERFORMING OPERATIONS; TRANSPORTING
B32—LAYERED PRODUCTS
B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
B32B27/00—Layered products comprising a layer of synthetic resin
B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
B32B27/065—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of foam
B—PERFORMING OPERATIONS; TRANSPORTING
B32—LAYERED PRODUCTS
B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
B32B5/20—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material foamed in situ
B—PERFORMING OPERATIONS; TRANSPORTING
B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
B—PERFORMING OPERATIONS; TRANSPORTING
B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
Abstract
This invention relates to a method for a manufacture of a plastic sandwich element in which a first extruder 12 is charged with essential ingredients for production of foamed cellular plastic at a predetermined temperature. A second extruder 16 or 20 is charged with essential ingredients for production of solid plastic skins at a temperature of at least 25 degrees Farenheit below the predetermined temperature. The resulting sandwich is extruded through an extrusion die 24 forming an integral plastic sandwich with the higher temperature of the foamed plastic layer C causing a partial melting of the outer skins A, B, thus ensuring good bonding of the skins A, B to the layer C.
Description
SPECIFICATION
Method of making foam core materials
This invention relates to a method of manufacturing integrally formed plastic sandwiches. More particularly, the invention relates to a process for the extrusion of integral plastic members having solid skins and a cellular inner portion.
Attempts have been made in the past to provide for the production of plastic sandwich structural elements by bonding solid plastic skin
members to the top and bottom surfaces of a cellular plastic core. However, this method of fabrication is costly since it requires the individual fabrication of the individual skin and core members, the application of a relatively costly
adhesive material and the clamping of the bonded structural element until the adhesive is set. In
addition, the difficulty in obtaining a high strength
bond over an extended surface using an adhesive
results in a product having a less than desirable
level of reliability.
Other methods for the fabrication of plastics sandwich members have in the past included a
molding process in which inert gas is dispersed in
a polymer melt, the polymer melt is introduced
into a mold and as the mold fills, the gas expands
within the material forming a cellular core while a solid plastic skin forms along the walls of the
mold. This method has the disadvantages of not
permitting close control over the skin thickness,
not permitting variations in material between the skin and the core and requiring a large and
consequently expensive mold for the production of
large plastic members.
Attempts have been made to co-extrude a
multi-layer plastic sandwich such as disclosed in the Patent to Chisholm et al, No. 3,557,256. This
patent no where discloses the concept of
providing a foamed core. In Thomas, No.
3,331,900 there is disclosed a skin coated foamed
plastic article. Shippers, No. 3,782,870 disclosed
an apparatus for partially foaming a portion of
extruded material by separating melt streams and
then rejoining the separate melt streams and
partially foaming one of the melt streams.
The present invention contemplates control of the bonding of a cellular core to the skin material utilizing the concept of temperature differences in the materials being co-extruded. According to the
present invention, a first extruder is charged with
essential ingredients for production of cellular plastic at a predetermined temperature. At least one second extruder is charged with essential
ingredients for production of solid plastic at a
temperature differing from and lower than said
predetermined temperature by at least 25 degrees
Farenheit. The temperature of the core can be
about the melt temperature of the skin facilitating
utilizing and intimate bonding of the core and skin
materials.Control means are provided for the
simultaneous operation of the first and second
extruders thus resulting in the extrusion of a
sandwich member having a core of cellular plastic and one or more integrally formed skin members of solid plastic. The characteristics of the resulting plastic sandwich element can be controlled to feature, as desired, high flexural strength, hardness relatively high flexural rigidity, relatively low weight and relatively low cost. By increasing and decreasing the speed of operation of the second extruders, the thickness of skin members may be increased or decreased.
It is therefore an object of the present invention to provide a method for the manufacture of an integrally formed coextruded plastic member having a core of cellular plastic and skin members of solid plastic.
Another object of the present invention is to provide an apparatus for the manufacture of an integrally formed coextruded plastic member having a core of cellular plastic and skin members of solid plastic with the plastic member having top and bottom sknis of a predetermined desired thickness so as to control the characteristics of the plastic sandwich.
Some of the advantages of the present invention is that the plastic sandwich material so produced is desirable for use as a cap liner. The product prevents product penetration in to the liner when used as a liner for caps, any product penetration stagnating behind the liner and attracting germs. The final product assures a smooth surface in contact with the contents of the product. The concept of tetnperature differential co-extrusion of the foam core provides for different degrees of resilience while also greatly providing for price advantage in that less material can be used. Further, the layers enable a better stamped liner allowing a sharp definition while providing for a stronger product.
The layers encasing the foam core at a various temperature when co-extruded provide for a desired cellstructure while in the event some cells blow too much and are open, the layers will seal these open cells thus forming a very resilient liner.
These, together with various ancillary objects of the present invention are obtained by this method of for manufacture of plastic sandwich elements, preferred embodiments being shown in the accompanying drawing by way of example only, wherein:
Fig. 1 is a longitudinal sectional view through a portion of an embodiment of an apparatus which can be used according to the present invention;
Fig. 2 is a cross sectional view illustrating schematically the construction of a co-extruded plastic sandwich with a retaining thick skin at a temperature of at least 25 degrees Farenheit lower than the core shown immediately after coextrusion;
Fig. 3 is a view similar to Fig. 2 after the core has additionally foamed; and,
Figs. 4 and 5 are views similar to Fig. 2 and 3 but illustrating the co-extruded plastic sandwich having a relatively thin skin coextruded at a temperature of at least 25 degrees Farenheit lower than the core.
With continuing reference to the accompanying
drawing, wherein like reference numerals
designate similar parts throughout the. va rious
views, reference numeral 10 is used to generally
designate a typical apparatus which can be used for the co-extruding of the plastic sandwich.
As shown three extruders are employed
arranged with the extruder 1 2 for the core being
arranged horizontally and with its auger 14
extending longitudinally. The extruders 16 and 20
and their augers 1 8 and 22 are shown arranged
vertically. It is to be understood that while this is a
space saving and convenient typical installation, in
accordance with the concepts of the present
invention the extruders can be disposed in any
suitable arrangement such as side by side,
angularly disposed, or even remote from each
other the material to be co-extruded being fed to a
sizeable die 24.
In the illustrated embodiment, the first extruder
12 includes a perforated plate 26 and a tapered
nozzle 29 through which core material C to be
extruded is fed to the die 24. Likewise, skin
material A feed by auger 18 passes through a
perforated plate 30 and through tapered nozzle 32
onto the foamed core material C and thence
through die 24. The skin material B feed by auger
22 passes through perforated plate 34 and
tapered nozzle 36 onto the core material C and
thence through die 24. This facilitates the
formation of top skin A of solid plastic and a
bottom skin B of solid plastic on the center core C
of cellular plastic of the integral plastic sandwich
member 100.The extruder 12 is charged with
essential ingredients for the production of cellular
plastic and the second extruder 16 and the third
extruder 20 are each charged with essential
ingredients for the production of solid plastics.
Control means are provided to control the
relative speeds of rotation of the augers 14, 18 and 22 to provide for delivery of selected and
sufficient quantities of the essential ingredients to
provide core material C and skin material A and B.
The present invention is adapted to use
practically all thermoplastic materials. The
thickness of the material may range from between
.010 inches to an inch ortwo while the thickness
of the skin material A and for B is in the order of
.001 to .010 inches, the balance being in the
thickness of core material C. A material for the
integrally formed plastic sandwich element 100
may be polyethylene which forms A and B of solid
polyethylene and a core C of the closed cell foam
polyethylene. The use of polyethylene is indicated
by way of example, only and other thermoplastics
materials having properties adapted for fabrication
by an extrusion process and which can be formed
into a foam or cellular state may be utilized using
the process and apparatus according to the
present invention.Of course, two, three, or more
layers may be used to obtain the desired thickness
and properties where this material is used as a
cap liner.
EXAMPLE 1
As shown in Fig. 2 and Fig. 3 plastic sandwich
110 is formed with the core material C being formed from a mixture of melted polyethylene,
powdered zinc stearate in amounts as conventionally employed as a stabilizer and
activator. A product sold by Uni-Royal under the
trade name of «Celogen A. Z» is employed as a foaming agent. Other conventional foaming agents may alternatively be employed. The
extrusion temperature of the core material C may
range from 300 to 400 degrees Farenheit at optimum operation and in this example the core
material temperature selected is 300 degrees
Farenheit. The skin material A and B employed is delivered at a rate so that the thickness is .010 inches and is relatively thick.While the temperature of this polyethylene may range from 200 to 350 degrees Farenheit, in this example the temperature of the skin is 275 degrees Farenheit and its melt point is above 275 degrees but below 300 degrees.
The use of thick skin permits for reasonable tensile strength while the added heat of the core will promote slight melting of the inner surfaces of the skin in a controlled manner. The thick layer promotes evenness of the final sandwich even if the added heat will slightly melt the skin and will allow for sufficient tensile stress and hardness.
The slight melting of the skin will permit foam material at V to slightly penetrate the skin for ensuring a good bond between skin and core.
EXAMPLE 2
In Figs. 4 and 5 there is shown an embodiment of the invention wherein a thin skin of a thickness of .001 inch is used at the same temperature as set forth in Example 1.This embodiment provides for a good expansion factor in the order of 400% with great resiliency, a shore hardness of 65 on a durometer and sufficient tensile stress to function well as a cap liner. The added heat of the core thus causes a slight melting of the skin and an intimate intermingling of skin and core material at W.
It is to be understood that the skin thickness may be increased or decreased as desired by increasing or decreasing the output (speed) of the extruder for the skin material without making any changes in the temperature of extruding.
A latitude of modification, substitution and change is intended in the foregoing disclosure, and in some instances, some features of the present invention may be employed without a corresponding use of other features.
Claims (5)
1. A method of manufacturing a coextruded article comprising the steps of mixing ingredients for a cellular plastic including a foaming agent and a a plastic in a plastic state for forming a core and at a predetermined temperature, mixing other ingredients for at least one solid plastic in a plastic state at a temperature differing from and lower than said predetermined temperature by at least twenty-five degrees Farenheit, for forming a skin for said core and then simultaneously coextruding said cellular plastic and solid plastic through a die, with the higher temperature of said core promoting intermingling and intimate bonding of said skin and said core.
2. A method of manufacturing a coextruded article according to claim 1, wherein said solid plastic is relatively thin so as to permit enlargement of said extruded article by foaming after extrusion through said die.
3. A method of manufacturing a coextruded article according to claim 1, wherein said solid plastic is relatively thick so as to inhibit enlargement of said extruded article.
4. A method of manufacturing a coextruded article according to claim 3, wherein said solid plastic is the order of .010 inch so that the enlargement of said core is maintained even.
5. A method of manufacturing a coextruded article according to claim 1, wherein the temperature of said core is at least high as the melt point of said skin.
GB7928336A
1978-08-14
1979-08-14
Method of making foam core articles
Expired
GB2030919B
(en)
Applications Claiming Priority (1)
Application Number
Priority Date
Filing Date
Title
US05/933,307
US4206165A
(en)
1976-03-26
1978-08-14
Method of co-extrusion with foam core
Publications (2)
Publication Number
Publication Date
GB2030919A
true
GB2030919A
(en)
1980-04-16
GB2030919B
GB2030919B
(en)
1982-12-15
Family
ID=25463715
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB7928336A
Expired
GB2030919B
(en)
1978-08-14
1979-08-14
Method of making foam core articles
Country Status (4)
Country
Link
DE
(1)
DE2924472C2
(en)
FI
(1)
FI69003C
(en)
FR
(1)
FR2433408B1
(en)
GB
(1)
GB2030919B
(en)
Cited By (3)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
EP0040824A2
(en)
*
1980-05-23
1981-12-02
SMAE-SOCIETA’ MERIDIONALE ACCESSORI ELASTOMERICI S.p.A
Process for continuously manufacturing bi-compound shaped articles and the bi-compound shaped articles so obtained
EP2431148A1
(en)
*
2010-09-17
2012-03-21
Technisch Bureel Panigo N.V.
Production of laminated styrene-polymerised sheets
BE1020212A5
(en)
*
2010-09-17
2013-06-04
Tech Bureel Panigo Nv
PRODUCTION OF LAYERED STYRENE POLYMERIZED PLATES.
Families Citing this family (2)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
US4514812A
(en)
*
1982-09-27
1985-04-30
Owens-Illinois, Inc.
Method and apparatus for controlling the thickness of a lamina of a coextruded laminate
DE10150804A1
(en)
2001-10-15
2003-04-24
Trw Automotive Safety Sys Gmbh
Method of manufacturing a vehicle steering wheel
Family Cites Families (2)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
DE1154264B
(en)
*
1956-11-20
1963-09-12
Reifenhaeuser Kg
Device for the continuous extrusion of molded bodies with a foam core and a shell made of thermoplastic material
DE2118318A1
(en)
*
1970-04-24
1971-11-04
Mitsubishi Rayon Co. Ltd.; Shin-Kobe Electric Machinery Co. Ltd.; Tokio
Synthetic resin structures, in particular structural elements, and processes for their production
1979
1979-06-18
DE
DE2924472A
patent/DE2924472C2/en
not_active
Expired
1979-08-08
FR
FR797920336A
patent/FR2433408B1/en
not_active
Expired – Lifetime
1979-08-10
FI
FI792489A
patent/FI69003C/en
not_active
IP Right Cessation
1979-08-14
GB
GB7928336A
patent/GB2030919B/en
not_active
Expired
Cited By (4)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
EP0040824A2
(en)
*
1980-05-23
1981-12-02
SMAE-SOCIETA’ MERIDIONALE ACCESSORI ELASTOMERICI S.p.A
Process for continuously manufacturing bi-compound shaped articles and the bi-compound shaped articles so obtained
EP0040824A3
(en)
*
1980-05-23
1982-04-28
Smae-Societa’ Meridionale Accessori Elastomerici S.P.A
Process for continuously manufacturing bi-compound shaped articles and the bi-compound shaped articles so obtained
EP2431148A1
(en)
*
2010-09-17
2012-03-21
Technisch Bureel Panigo N.V.
Production of laminated styrene-polymerised sheets
BE1020212A5
(en)
*
2010-09-17
2013-06-04
Tech Bureel Panigo Nv
PRODUCTION OF LAYERED STYRENE POLYMERIZED PLATES.
Also Published As
Publication number
Publication date
FI69003B
(en)
1985-08-30
DE2924472A1
(en)
1980-02-28
FI792489A
(en)
1980-02-15
FR2433408A1
(en)
1980-03-14
DE2924472C2
(en)
1982-12-30
GB2030919B
(en)
1982-12-15
FI69003C
(en)
1985-12-10
FR2433408B1
(en)
1991-09-20
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Legal Events
Date
Code
Title
Description
1999-09-08
PE20
Patent expired after termination of 20 years
Effective date:
19990813
