WO2014135338A1 - Adhesive tape without release layer - Google Patents

Adhesive tape without release layer Download PDF

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Publication number
WO2014135338A1
WO2014135338A1 PCT/EP2014/052520 EP2014052520W WO2014135338A1 WO 2014135338 A1 WO2014135338 A1 WO 2014135338A1 EP 2014052520 W EP2014052520 W EP 2014052520W WO 2014135338 A1 WO2014135338 A1 WO 2014135338A1
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WO
WIPO (PCT)
Prior art keywords
layer
adhesive tape
adhesive
tape according
skin layer
Prior art date
Application number
PCT/EP2014/052520
Other languages
French (fr)
Inventor
Alessandro Lepori
Original Assignee
Vibac S.P.A.
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.)
Filing date
Publication date
Application filed by Vibac S.P.A. filed Critical Vibac S.P.A.
Publication of WO2014135338A1 publication Critical patent/WO2014135338A1/en

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Classifications

    • 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
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • 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
    • B32B27/08—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 synthetic resin
    • 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
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B32B27/283—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polysiloxanes
    • 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
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/06—Interconnection of layers permitting easy separation
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/12—Chemical modification
    • C08J7/123—Treatment by wave energy or particle radiation
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/201—Adhesives in the form of films or foils characterised by their carriers characterised by the release coating composition on the carrier layer
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/29—Laminated material
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/518—Oriented bi-axially
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/748—Releasability
    • 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
    • B32B2405/00—Adhesive articles, e.g. adhesive tapes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/10—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet
    • C09J2301/16—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the structure of the carrier layer
    • C09J2301/162—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the structure of the carrier layer the carrier being a laminate constituted by plastic layers only
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/40—Additional features of adhesives in the form of films or foils characterized by the presence of essential components
    • C09J2301/414—Additional features of adhesives in the form of films or foils characterized by the presence of essential components presence of a copolymer
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2423/00—Presence of polyolefin
    • C09J2423/10—Presence of homo or copolymers of propene
    • C09J2423/105—Presence of homo or copolymers of propene in the release coating
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2423/00—Presence of polyolefin
    • C09J2423/10—Presence of homo or copolymers of propene
    • C09J2423/106—Presence of homo or copolymers of propene in the substrate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2423/00—Presence of polyolefin
    • C09J2423/16—Presence of ethen-propene or ethene-propene-diene copolymers
    • C09J2423/165—Presence of ethen-propene or ethene-propene-diene copolymers in the release coating
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2483/00—Presence of polysiloxane
    • C09J2483/005—Presence of polysiloxane in the release coating

Definitions

  • the present invention relates to an adhesive tape, namely to a pressure-sensitive product intended for sealing packages and for generic industrial use, and to the associated production method.
  • such an adhesive tape typically comprises a support layer based on substantially homopolymeric bioriented polypropylene (BOPP) and an adhesive layer.
  • BOPP substantially homopolymeric bioriented polypropylene
  • the latter is typically based on natural rubber and hydrocarbon resins dissolved in solvent, such as hexane, or based on thermoplastic rubber and hydrocarbon resins, namely hot melt adhesives.
  • an anti-adhesive release layer is applied on the opposite side of the support layer from that facing towards the adhesive layer, which release layer is capable of ensuring unrolling of the finished tape.
  • the anti-adhesive substance generally based on polyvinyl carbamate, is applied in the form of a solution in xylene and/or toluene. After the deposition thereof, the tape passes through a drying tunnel, in order to remove the solvent, which is then recovered.
  • EP-0 965 625 Al describes an adhesive tape which can be made without a release layer by making use of a BOPP film having a "skin" composed of high density polyethylene (HDPE).
  • the high density polyethylene does not, however, ensure ideal adhesion to the homopolymer polypropylene film due to the physicochemical incompatibility between the two materials.
  • Such a tape thus exhibits an unwind force which is much higher than that of an adhesive tape having a standard release layer of the above-stated kind.
  • using HDPE on equipment normally used for polypropylene leads to a decline in the yield and efficiency of the production process.
  • Example 1 of prior art document US-4 673 61 1 discloses a tape having an adhesive layer of rubber and a support therefor including a surface layer opposite to the adhesive layer and containing 1.5 % by weight of dimethylpolysiloxane.
  • An object of the present invention is therefore that of providing an adhesive tape of the general type indicated at the beginning of the present description, which exhibits optimum application characteristics, in particular with regard to unwindability while still lacking a release layer applied by means of solvent.
  • an adhesive tape comprising a support layer and an adhesive layer of the hot melt type, as well as a skin layer located on the opposite side of the support layer from that facing towards the adhesive layer, said skin layer being formed of a propylene -butene copolymer, a propylene-ethylene -butene terpolymer, a propylene homopolymer or mixtures thereof, there furthermore being present in said skin layer a quantity of between 32,000 and 100,000 ppm of polyorganosiloxane having a viscosity of
  • the tape of the present invention has the advantage that it can be produced in a straightforward and economic manner. This is because dispensing with the release layer permits considerable savings in terms of raw materials and manufacturing energy costs, which are due inter alia to the necessity of recovering the solvent used for spreading the release agent. As a consequence, there are lower emissions of solvent into the atmosphere and the risks associated with storing considerable quantities of flammable and harmful solvents are reduced.
  • the provision of a skin layer containing fairly high amounts of polyorganosiloxane of high viscosity allows to the user to smoothly draw the desired length of tape without having to exercise high traction forces which would break the tape, even when an "hot melt” adhesive layer is present.
  • the present invention further provides a production method for the above-stated adhesive tape by co-extrusion of the support layer and the skin layer, and subsequent application of the adhesive layer. Said method makes it possible to simplify the adhesive spreading operation and the associated equipment: in particular, hot melt technology, which already does not involve using an adhesive comprising solvent, becomes completely "solventless".
  • production of an adhesive tape without a release layer provides the use of a film having a support layer and a "skin" (namely an outer layer forming the back of the adhesive tape) obtained by coextrusion, with a thickness which typically varies from 0.5 to 3 microns, and formed from a C3-C4 (propylene, butene) copolymer or from a C3-C2-C4 (propylene, ethylene, butene) terpolymer or from a C3 (propylene) homopolymer, which contains a quantity of polyorganosiloxane (32,000 ppm to
  • the outer surface of the skin is flame- or corona-treated to increase the anti-adhesive effect.
  • substantially homopolymeric polypropylene The remainder of the film is generally composed of substantially homopolymeric polypropylene. It should be noted that, in the context of the present description, "substantially homopolymeric polypropylene” should be taken to mean a polypropylene which may contain up to 3% of ethylene.
  • the opposite side of the film is also flame- or corona-treated to ensure excellent adhesion with the adhesive compound which will be applied thereon.
  • particulate substances based on synthetic silica, clay, PMMA of a mean size of around 3-4 microns may be present on the surface of both outer sides of the film as antiblocking agents. These substances are typically mixed into the polymer in the form of a masterbatch during the extrusion phase.
  • the above-stated film is advantageously produced using a Brueckner Maschinenbau GmbH & Co KG LISIM ® double-bubble sequential stretching/simultaneous stretching installation with a longitudinal stretching ratio (MDx) of between 4 and 7 and a transverse stretching ratio (TDx) of between 6 and 11.
  • the total thickness of the adhesive tape is advantageously between 20 and 60 microns.
  • Examples of commercially available homopolymer PP which may be used are: Moplen HP522H - LyondellBasell; Sabic® PP 524P - Sabic; Moplen 2152 HOXP - LyondellBasell; Moplen HP422H - LyondellBasell; 100-GD02 INEOS Polyolefms.
  • Adsyl 3C30F HP - LyondellBasell Adsyl 5C39F - LyondellBasell
  • Eltex® P KS359 - INEOS Polyolefms Eltex® P KS357 - INEOS Polyolefms.
  • Masterbatches which may be used for the polysiloxane component of the skin layer, which forms the back of the adhesive tape, advantageously have the characteristics shown in Table III.
  • a film of a total thickness of 25 microns is produced having the following three-layer structure in which layer A is the skin layer and layer B the support layer:
  • Layer A contains thus polydimethylsiloxane in a quantity of 40,000 ppm. Both sides of the film are subjected to corona treatment.
  • the film was produced with a sequential stretching installation, with a longitudinal stretching ratio (MDx) of 5 and a transverse stretching ratio (TDx) of 9.
  • Said film was then used to produce an adhesive tape with "hot melt” technology which involves hot application of an adhesive based on thermoplastic rubber and hydrocarbon resins onto layer C.
  • the adhesive was applied in a quantity, measured when dry, of 16.0 g/m 2 .
  • composition of the adhesive used is stated in Table IV below.
  • a release layer based on polyvinyl carbamate was applied onto one part of the back (or skin layer A) of the resultant adhesive tape, while no release layer was applied onto the remaining part of the back.
  • Table V below shows the experimental data obtained for the two parts of the adhesive tape, which were or were not provided with a release layer.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Adhesive Tapes (AREA)

Abstract

The adhesive tape comprises a support layer and an adhesive layer of the hot melt type, as well as a skin layer located on the opposite side of the support layer from that facing towards the adhesive layer. The skin layer is formed of a propylene -butene copolymer, a propylene-ethylene-butene terpolymer, a propylene homopolymer or mixtures thereof. It is furthermore present in the skin layer a quantity of between 32,000 and 100,000 ppm of polyorganosiloxane having a viscosity of between 10,000 mm2/s and 2,000,000 mm2/s, which viscosity is measured at 25°C according to ASTM D445.

Description

Adhesive tape without release layer
The present invention relates to an adhesive tape, namely to a pressure-sensitive product intended for sealing packages and for generic industrial use, and to the associated production method.
More particularly, such an adhesive tape typically comprises a support layer based on substantially homopolymeric bioriented polypropylene (BOPP) and an adhesive layer. The latter is typically based on natural rubber and hydrocarbon resins dissolved in solvent, such as hexane, or based on thermoplastic rubber and hydrocarbon resins, namely hot melt adhesives.
According to a prior art, an anti-adhesive release layer is applied on the opposite side of the support layer from that facing towards the adhesive layer, which release layer is capable of ensuring unrolling of the finished tape. The anti-adhesive substance, generally based on polyvinyl carbamate, is applied in the form of a solution in xylene and/or toluene. After the deposition thereof, the tape passes through a drying tunnel, in order to remove the solvent, which is then recovered. On the other hand, EP-0 965 625 Al describes an adhesive tape which can be made without a release layer by making use of a BOPP film having a "skin" composed of high density polyethylene (HDPE). The high density polyethylene does not, however, ensure ideal adhesion to the homopolymer polypropylene film due to the physicochemical incompatibility between the two materials. Such a tape thus exhibits an unwind force which is much higher than that of an adhesive tape having a standard release layer of the above-stated kind. Furthermore, using HDPE on equipment normally used for polypropylene leads to a decline in the yield and efficiency of the production process.
Example 1 of prior art document US-4 673 61 1 discloses a tape having an adhesive layer of rubber and a support therefor including a surface layer opposite to the adhesive layer and containing 1.5 % by weight of dimethylpolysiloxane. An object of the present invention is therefore that of providing an adhesive tape of the general type indicated at the beginning of the present description, which exhibits optimum application characteristics, in particular with regard to unwindability while still lacking a release layer applied by means of solvent.
Said object is achieved thanks to an adhesive tape comprising a support layer and an adhesive layer of the hot melt type, as well as a skin layer located on the opposite side of the support layer from that facing towards the adhesive layer, said skin layer being formed of a propylene -butene copolymer, a propylene-ethylene -butene terpolymer, a propylene homopolymer or mixtures thereof, there furthermore being present in said skin layer a quantity of between 32,000 and 100,000 ppm of polyorganosiloxane having a viscosity of
2 2
between 10,000 mm /s and 2,000,000 mm /s, which viscosity is measured at 25°C according to ASTM D445. Preferred embodiments of the tape of the invention are stated in the claims dependent on claim 1.
The tape of the present invention has the advantage that it can be produced in a straightforward and economic manner. This is because dispensing with the release layer permits considerable savings in terms of raw materials and manufacturing energy costs, which are due inter alia to the necessity of recovering the solvent used for spreading the release agent. As a consequence, there are lower emissions of solvent into the atmosphere and the risks associated with storing considerable quantities of flammable and harmful solvents are reduced.
Furthermore, according to the invention, the provision of a skin layer containing fairly high amounts of polyorganosiloxane of high viscosity allows to the user to smoothly draw the desired length of tape without having to exercise high traction forces which would break the tape, even when an "hot melt" adhesive layer is present. The present invention further provides a production method for the above-stated adhesive tape by co-extrusion of the support layer and the skin layer, and subsequent application of the adhesive layer. Said method makes it possible to simplify the adhesive spreading operation and the associated equipment: in particular, hot melt technology, which already does not involve using an adhesive comprising solvent, becomes completely "solventless".
According to the invention, production of an adhesive tape without a release layer provides the use of a film having a support layer and a "skin" (namely an outer layer forming the back of the adhesive tape) obtained by coextrusion, with a thickness which typically varies from 0.5 to 3 microns, and formed from a C3-C4 (propylene, butene) copolymer or from a C3-C2-C4 (propylene, ethylene, butene) terpolymer or from a C3 (propylene) homopolymer, which contains a quantity of polyorganosiloxane (32,000 ppm to
2 2 100,000 ppm) of a viscosity of between 10,000 mm /s and 2,000,000 mm /s , and
2 2
preferably between 50,000 mm /s and 500,000 mm /s. Advantageously, the outer surface of the skin is flame- or corona-treated to increase the anti-adhesive effect.
The remainder of the film is generally composed of substantially homopolymeric polypropylene. It should be noted that, in the context of the present description, "substantially homopolymeric polypropylene" should be taken to mean a polypropylene which may contain up to 3% of ethylene.
Advantageously, the opposite side of the film is also flame- or corona-treated to ensure excellent adhesion with the adhesive compound which will be applied thereon.
Furthermore, particulate substances based on synthetic silica, clay, PMMA of a mean size of around 3-4 microns may be present on the surface of both outer sides of the film as antiblocking agents. These substances are typically mixed into the polymer in the form of a masterbatch during the extrusion phase. The above-stated film is advantageously produced using a Brueckner Maschinenbau GmbH & Co KG LISIM® double-bubble sequential stretching/simultaneous stretching installation with a longitudinal stretching ratio (MDx) of between 4 and 7 and a transverse stretching ratio (TDx) of between 6 and 11.
The total thickness of the adhesive tape is advantageously between 20 and 60 microns.
The preferred characteristics of the homopolymer PP used for the support layer are stated in Table I below.
TABLE I
Figure imgf000005_0001
Examples of commercially available homopolymer PP which may be used are: Moplen HP522H - LyondellBasell; Sabic® PP 524P - Sabic; Moplen 2152 HOXP - LyondellBasell; Moplen HP422H - LyondellBasell; 100-GD02 INEOS Polyolefms.
The characteristics of the preferred polyolefmic materials used for the skin layer are stated in Table II.
TABLE II
MT Vicat Melt index
(melting temperature) (softening point) (ISO 1133; 230°C, 2.16 kg) ASTM D 3417 A50 (50°C/h 10N)
ISO 306
100-145°C 90-135°C 1.5-11 g/lO min Examples of commercially available copolymers which may be used are: Adsyl 3C30F HP - LyondellBasell; Adsyl 5C39F - LyondellBasell; Eltex® P KS359 - INEOS Polyolefms; Eltex® P KS357 - INEOS Polyolefms.
Masterbatches which may be used for the polysiloxane component of the skin layer, which forms the back of the adhesive tape, advantageously have the characteristics shown in Table III.
TABLE III
Figure imgf000006_0001
Further advantages and features of the present invention will become clear from the following exemplary embodiment which is provided by way of non-limiting example.
Example
A film of a total thickness of 25 microns is produced having the following three-layer structure in which layer A is the skin layer and layer B the support layer:
A ADSYL 5C39F (LyondellBasel) 50% + SAB 06579 PPR (Constab) 50% 1 μιη B MOPLEN HP522H (LyondellBasell)
C ADSYL 5C39F (LyondellBasell) 1 μιη
Layer A contains thus polydimethylsiloxane in a quantity of 40,000 ppm. Both sides of the film are subjected to corona treatment. The film was produced with a sequential stretching installation, with a longitudinal stretching ratio (MDx) of 5 and a transverse stretching ratio (TDx) of 9.
Said film was then used to produce an adhesive tape with "hot melt" technology which involves hot application of an adhesive based on thermoplastic rubber and hydrocarbon resins onto layer C. The adhesive was applied in a quantity, measured when dry, of 16.0 g/m2.
The composition of the adhesive used is stated in Table IV below.
TABLE IV - Adhesive composition
Figure imgf000007_0001
Total (%) 100.00
A release layer based on polyvinyl carbamate was applied onto one part of the back (or skin layer A) of the resultant adhesive tape, while no release layer was applied onto the remaining part of the back.
Table V below shows the experimental data obtained for the two parts of the adhesive tape, which were or were not provided with a release layer.
TABLE V
Parameter Method (unit of Adhesive tape Adhesive tape measurement) without with release release layer layer
Figure imgf000008_0001
As may be seen, the results obtained on both parts of the tape are substantially similar, confirming that the tape of the invention makes it possible to dispense with the application of a release layer, so avoiding the associated costs and drawbacks, but without suffering substantial performance penalties.
For comparison purposes, a further tape having the same structure and composition of the above-disclosed tape of the invention, except that Layer A contains polydimethylsiloxane in a quantity of 20,000 ppm, exhibits an unwind force measured according to PSTC-8 of 180 g/cm.
Naturally, the principle of the invention remaining the same, the details of construction and forms of embodiment may be varied widely with respect to those described, which have been given purely by way of example, without thereby departing from the scope thereof. For example, further layers could be interposed between the support layer and the adhesive layer.

Claims

1. Adhesive tape comprising a support layer and an adhesive layer of the hot melt type, as well as a skin layer located on the opposite side of the support layer from that facing towards the adhesive layer, said skin layer being formed of a propylene -butene copolymer, a propylene-ethylene-butene terpolymer, a propylene homopolymer or mixtures thereof, there furthermore being present in said skin layer a quantity of between 32,000 and 100,000 ppm of polyorganosiloxane having a viscosity of between 10,000
2 2
mm /s and 2,000,000 mm /s, which viscosity is measured at 25°C according to ASTM D445.
2. Adhesive tape according to Claim 1 , in which said support layer is formed from substantially homopolymeric polypropylene, namely a polypropylene which may contain up to 3% of ethylene.
3. Adhesive tape according to Claim 1 or 2, in which said skin layer has a thickness of between 0.5 and 3 microns.
4. Adhesive tape according to any one of the preceding claims, having a total thickness of between 20 and 60 microns.
5. Adhesive tape according to any one of the preceding claims, in which the outer side of said skin layer and/or the side of said support layer facing towards the adhesive layer has/have been subjected to flame or corona treatment.
6. Adhesive tape according to any one of the preceding claims, comprising at least one further layer interposed between the support layer and the adhesive layer..
7. Adhesive tape according to any one of the preceding claims, in which said
2 2 polyorganosiloxane has a viscosity of between 50,000 mm /s and 500,000 mm /s.
8. Method for producing an adhesive tape according to any one of the preceding claims, which provides the steps of coextruding a film comprising a support layer and a skin layer, and of subsequently applying an adhesive layer onto one side of the film.
9. Method according to Claim 8, in which said coextrusion proceeds with biaxial stretching, with a longitudinal stretching ratio of between 4 and 7 and a transverse stretching ratio of between 6 and 11.
PCT/EP2014/052520 2013-03-06 2014-02-10 Adhesive tape without release layer WO2014135338A1 (en)

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EP13425035 2013-03-06
EP13425035.6 2013-03-06

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4673611A (en) * 1984-06-15 1987-06-16 Hoechst Aktiengesellschaft Support film and pressure-sensitive adhesive tape
US4716068A (en) * 1985-01-19 1987-12-29 Hoechst Aktiengesellschaft Polypropylene adhesive tape

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4673611A (en) * 1984-06-15 1987-06-16 Hoechst Aktiengesellschaft Support film and pressure-sensitive adhesive tape
US4716068A (en) * 1985-01-19 1987-12-29 Hoechst Aktiengesellschaft Polypropylene adhesive tape

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