Office Action 1: Non-Final Rejection (2025-03-24)
Rejection types: 103 - Obviousness, 112 - Written Description/Enablement

CLAIMS:
AMENDMENTS TO THE CLAIMS

This listing of claims replaces all prior versions and listings of claims in the application.

1\. (Original) A supercalendered kraft paper suitable for use as a substrate layer of an industrial release liner for adhesive labels, the supercalendered kraft paper comprising - a basis weight in the range of 50 to 70 g/m2, when determined according to ISO 536, and - a fiber furnish determinable with standard ISO 9184-4 in conjunction with standard ISO 9184-1, the fiber furnish comprising o bleached hardwood kraft pulp, o bleached softwood kraft pulp and o bleached chemithermomechanical pulp, such that the supercalendered kraft paper contains - the bleached chemithermomechanical pulp in an amount equal to or higher than 5 wt.% and the bleached softwood kraft pulp in an amount equal to or higher than 15 wt.%, when determined as dry matter content of the paper according to SCAN-P 39:80, the supercalendered kraft paper thereby having - a transparency level equal to or higher than 40%, when determined according to ISO 2469 and - a density in the range of 1040 to 1140 kg/m3, when determined according to ISO 534.
2\. (Currently Amended) A method of manufacturing supercalendered kraft paper suitable for use as a substrate layer of an industrial release liner for adhesive labels, the method comprising - mixing together o bleached hardwood kraft pulp, o bleached softwood kraft pulp, and o bleached chemithermomechanical pulp such that a pulp mixture is obtained, which has a fiber furnish determinable with standard ISO 9184-4 in conjunction with the standard ISO 9184-1, - forming a paper web from the pulp mixture on a paper machine, - reducing moisture content of the paper web in a press section, - drying the paper web in a drying section, thereby forming paper, and - calendering the paper, - such that a supercalendered kraft paper is obtained having a basis weight in the range of 50 to 70 g/m2, and which contains the bleached chemithermomechanical pulp in an amount equal to or higher than 5 wt.% and the bleached softwood kraft pulp in an amount equal to or higher than 15 wt.%, when determined as dry matter content of the paper according to SCAN P 39:80, the supercalendered kraft paper thereby having - a transparency level equal to or higher than 40%, when determined according to ISO 2469 and - a density in the range of 1040 to 1140 kg/m3, when determined according to ISO 534.
3\. (Currently Amended) The method according to claim 2, wherein upon mixing, the bleached chemithermomechanical pulp has a Schopper-Riegler number - t in the range of 25 to 55 , when determined according to ISO 5267-1.
4\. (Currently Amended) The paper according to claim 1 wherein the fiber furnish has an average length weighted fiber length . . ., , in the range of 0.90 to 1.14 mm, e when determined according to ISO 16065-2: 2014.
5\. (Currently Amended) The paper according to lai. wherein the fiber furnish has an average fiber width e , in the range of 22 to 25 micrometers, --C---- - V- --) -V - ^\` when determined according to ISO 16065-2: 2014.
6\. (Currently Amended) The paper according to wherein the supercalendered kraft paper contains the bleached softwood kraft pulp in an amount in the range of 15 to 65 wt.%, ICII L 1 i , Piiii i when determined as dry matter content of the paper according to SCAN-P 39:80.
7\. (Currently Amended) The paper according to wherein the supercalendered kraft paper contains the bleached chemithermomechanical pulp in an amount in the range of 5 to 50 wt.%, when determined as dry matter content of the paper according to SCAN-P 39:80.
8\. (Currently Amended) The paper according to , the bleached chemithermomechanical pulp comprising fibers from softwood, the softwood being a coniferous tree, preferably from the genus Picea, Abies, Larix or Pinus .
9\. (Currently Amended) The paper according to , the bleached chemithermomechanical pulp comprising fibers from hardwood, the hardwood being a broadleaved tree, preferably from the genus Betula, Acer, Populus or Eucalyptus
10\. (Currently Amended) The paper according to wherein the share of softwood fibers in the bleached chemithermomechanical pulp is in the range 10 to 60 wt.%, - when determined as dry matter content of the bleached chemithermomechanical pulp according to SCAN-P 39:80.
11\. (Currently Amended) The paper according to wherein the basis weight of the paper is in the range of 52 to 68 g/m2, -flx in tho ranva of E when determined according to ISO 536.
12\. (Currently Amended) The paper ' ^ according to \*-6 n lain, wherein the supercalendered kraft paper has a transparency in the range of 40 to 56%, when determined according ISO 2469.
13\. (Currently Amended) The paper according to the supercalendered kraft paper comprising CIE L\*, a\*, b\* colour space coordinate values, wherein - L\* is in the range of 92 to 98, - a\* is in the range of -4 to +2, and - b\*isin the range of+5 to+11 when determined by means of diffuse reflectance method with the elimination of specular gloss, using 20 standard observer, in accordance with ISO 5631-1:2015(en).
14\. (Currently Amended) The paper according to wherein the supercalendered kraft paper has a density in the range of 1040 to 1120 - nrfer' kg/m3, when determined according to ISO 534.
15\. (Currently Amended) The paper according to wherein the fiber furnish of the supercalendered kraft paper has a water retention value ;. x . in the range of 1.50 to 1.90 g/g , when determined according to ISO 23714:2014 from a sample having a dry matter content of 1 gram.
16\. (Currently Amended) The paper according to the fiber furnish comprising - bleached hardwood kraft pulp in an amount equal to or less than 35 wt.%, - bleached softwood kraft pulp in an amount equal to or higher than 15 wt.% and - bleached chemithermomechanical pulp in an amount equal to or higher than 35 wt.%, when determined as dry matter content of the paper according to SCAN-P 39:80.
17\. (Currently Amended) The paper according to the supercalendered kraft paper having a tear index in the cross direction of the paper higher than 5 mNm2/g, when determined according to ISO 1974.

18\. (Currently Amended) A release liner comprising a substrate layer and a release coating, wherein the substrate layer is a supercalendered kraft paper according to which comprises a primer coating applied on at least one side of the supercalendered kraft paper.
2 3 4 5 6

OFFICE ACTION:
Detailed Office Action
The communication dated 2/24/2023 has been entered and fully considered.
Claims 1-18 are pending.
Notice of Pre-AIA  or AIA  Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b)  CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 9 and 10 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA  35 U.S.C. 112, the applicant), regards as the invention.
Regarding claims 9 and 10, the phrase preferably renders the claim indefinite because it is unclear whether the limitation(s) following the phrase are part of the claimed invention.  See MPEP § 2173.05(d).
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary.  Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-18 are rejected under 35 U.S.C. 103 as being unpatentable over EP 3059344 A1 ANTILLA et al., hereinafter ANTILLA, in view of WO 2020/084188 A1 ANTILLA, hereinafter ANTILLA II.
As for claims 1 and 2, ANTILLA discloses supercalendering of glassine paper [0051].  The Examiner notes that the intended use of the paper in the preamble is non-limiting, nevertheless, ANTILLA discloses that the glassine paper is suitable for a release liner [0051].  ANTILLA discloses that the paper comprises both bleached hardwood and softwood chemical pulps [0077] and those chemical pulps can be kraft chemical pulps [0058] (A supercalendered kraft paper suitable for use as a substrate layer of an industrial release liner for adhesive labels, the supercalendered kraft paper comprising).
ANTILLA discloses a basis weight of 57 g/m2 [0077] which falls within the claimed range (a basis weight in the range of 50 to 70 g/m2, when determined according to ISO 536).
ANTILLA discloses that the furnish comprises, bleached chemical hardwood, bleached chemical softwood and bleached CTMP pulp [0077] (fiber furnish determinable with standard ISO 9184-4 in conjunction with standard ISO 9184-1, the fiber furnish comprising of bleached hardwood kraft pulp, of bleached softwood kraft pulp and of bleached chemithermomechanical pulp)
ANTILLA discloses 25% bleached CTMP which falls within the claimed range [0077] (such that the supercalendered kraft paper contains - the bleached chemithermomechanical pulp in an amount equal to or higher than 5 wt.%).
ANTILLA discloses a transparency of 46.5% which falls within the claimed range [0078] (the supercalendered kraft paper thereby having - a transparency level equal to or higher than 40%, when determined according to ISO 2469).
ANTILLA discloses a density of 1087 kg/m2 which falls within the claimed range [0077] (a density in the range of 1040 to 1140 kg/m3, when determined according to ISO 534).
ANTILLA discloses a mixture of bleached softwood and hardwood kraft chemical pulps.  ANTILLA does not disclose the specific amount of hardwood and softwood.  However, ANTILLA recognizes that the split of hardwood and softwood is a result effective variable.  ANTILLA discloses that hardwood fibers provide greater brightness which increases transparency [0029, 0033] while softwood fibers provide greater strength properties.  At the time of the invention it would be obvious to the person of ordinary skill in the art to optimize the amount of hardwood and softwood kraft chemical fibers through routine optimization to achieve a balance between strength and brightness/transparency (the bleached softwood kraft pulp in an amount equal to or higher than 15 wt.%, when determined as dry matter content of the paper according to SCAN-P 39:80).
Furthermore, the Examiner notes that differences in concentration will not typically support non-obviousness absent evidence of unexpected results.
In the alternative, if necessary, ANTILLA II discloses release papers which comprise bleached kraft chemical pulps [pg. 32 lines 5-10].  ANTILLA II discloses that hardwood fibers provide brightness and transparency while softwood fibers provide strength [pg. 30 lines 5-20].  ANTILLA II discloses a split of fibers of 10-35% which overlaps with the instant claimed range [pg. 31 lines 5-9].
At the time of the invention it would be obvious to the person of ordinary skill in the art to apply the known concentration of hardwood and softwood chemical kraft pulps for release liner of ANILLA II to the chemical pulp concentrations of ANTILLA.  The person of ordinary skill in the art would be motivated to do so to achieve the desired balance between the properties offered by hardwoods and softwoods.
As for claim 3, ANTILLA discloses that the bleached CTMP may have an SR of 25 to 55 [0058] which falls within the claimed range.
As for claim 4 and 5, as ANTILLA and if necessary, ANTILLA II, teach the substantially the same fiber composition (kraft hardwood, kraft softwood, BCTMP) at substantially the same degree of refining (SR) for the backing later of a release liner it would be expected to have substantially the same length weighted average fiber length and average fiber width.  Fiber length and fiber width are dependent on the type of fibers used and the degree of refining (SR value).  Alternatively, fiber type (hardwood (short fibers) vs softwood (long fibers)) is a result effective variable (see supra).  At the time of the invention it would be obvious to optimize the proportion of hardwood and softwood and therefore the average fiber length/width through routine optimization.
As for claim 6, ANTILLA discloses 25% bleached CTMP which falls within the claimed range [0077].
As for claim 7, ANTILLA discloses 25% bleached CTMP which falls within the claimed range [0077]
As for claims 8 and 9, ANTILLA discloses that the bleached CTMP comprises both hardwood and softwood fibers [0077].  ANTILLA discloses the hardwood aspen (genus populus) and the softwood spruce (genus Picea) [0076].
As for claim 10, ANTILLA discloses that the softwood can be present in the mixture of hardwood and softwood bleached CTMP of 10 to 35% which falls within the claimed range [0112].
As for claim 11, ANTILLA discloses a basis weight of 57 g/m2 [0077] which falls within the claimed range.
As for claim 12, ANTILLA discloses a transparency of 46.5% which falls within the claimed range [0078].
As for claim 13, ANTILLA discloses bleached kraft chemical pulp and bleached CTMP pulp for the release liner paper.  ANTILLA does not disclose how bright the paper should be ANTILLA II discloses a lightness (L*) of at least 94% which overlaps the instant claimed range, an a* of -5 to 1 which overlaps the instant claimed range and a b* of 4 to 10 which overlaps the instant claimed range [pg. 41 lines 20-30].    At the time of the invention it would be obvious to the person of ordinary skill in the art to apply the known CIE L*a*b* values of ANTILLA II to the release liner of ANTILLA.  The person of ordinary skill in the art would be motivated to do so to improve the product by increasing the market are at which it is sold [ANTILLA II pg.41 lines 30-35].  The person of ordinary skill in the art would expect success as ANTILLA states that release papers should be bleached such that they have whiteness and brightness [0028].
As for claim 14, ANTILLA discloses a density of 1087 kg/m2 which falls within the claimed range [0077].
As for claims 15 and 17, as ANTILLA teaches substantially the same furnish composition and substantially the same degree of refining it would be expected the furnish would have substantially the same water retention value and tear index.  The properties of a composition cannot be separated from the composition itself.
As for claim 16, ANTILLA discloses an example of paper with 35% bleached CTMP and the remainder of chemical pulp [0089].
ANTILLA discloses a mixture of bleached softwood and hardwood kraft chemical pulps.  ANTILLA does not disclose the specific amount of hardwood and softwood.  However, ANTILLA recognizes that the split of hardwood and softwood is a result effective variable.  ANTILLA discloses that hardwood fibers provide greater brightness which increases transparency [0029, 0033] while softwood fibers provide greater strength properties.  At the time of the invention it would be obvious to the person of ordinary skill in the art to optimize the amount of hardwood and softwood kraft chemical fibers through routine optimization to achieve a balance between strength and transparency (the bleached softwood kraft pulp in an amount equal to or higher than 15 wt.%, when determined as dry matter content of the paper according to SCAN-P 39:80).
Furthermore, the Examiner notes that differences in concentration will not typically support non-obviousness absent evidence of unexpected results.
In the alternative, if necessary, ANTILLA II discloses release papers which comprise bleached kraft chemical pulps [pg. 32 lines 5-10].  ANTILLA II discloses that hardwood fibers provide brightness and transparency while softwood fibers provide strength [pg. 30 lines 5-20].  ANTILLA II discloses a split of fibers of 10-35% which overlaps with the instant claimed range [pg. 31 lines 5-9].  With 35% BTCMP and 10-35% softwood this leaves 30-55% bleached chemical hardwood which overlaps the instant claimed range
At the time of the invention it would be obvious to the person of ordinary skill in the art to apply the known concentration of hardwood and softwood chemical kraft pulps for release liner of ANILLA II to the chemical pulp concentrations of ANTILLA.  The person of ordinary skill in the art would be motivated to do so to achieve the desired balance between the properties offered by hardwoods and softwoods.
As for claim 18, ANTILLA discloses a release coating on the supercalendered paper [0002].
Conclusion


NEXT OFFICE ACTION: Notice of Allowability
Reasons for Allowance
The following is an examiner’s statement of reasons for allowance: The closest prior art was ANTILLA in view of ANTILLA II.  The Examiner found convincing the applicant’s arguments regarding length-weighted average fiber length and tear value [Applicant’s arguments 6/24/2025 pg.9 par. 1, 4 and 5].  Neither of these were explicitly disclosed in the prior art for a supercalendered paper with a mix of BCTMP, and bleached hard/softwood kraft.  An additional art, EP 4,310,249 SANTMARTI, did teach a fiber length of 0.9 to 1.1 mm (900 and 1,100 micrometers), with the wood comprising bleached kraft and BCTMP.  However, the refence did not state whether this was average fiber length or length-weighted average fiber length (these ae two different ways of measuring fiber length in the pulp and paper industry along with weight-weighted average fiber length).
Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee.  Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.”
Conclusion

CITED REFERENCE SUMMARIES: Ref EP3059344A1: Claims:
A paper (PAP1) suitable for use as a layer of a release liner, the paper having density equal to or less than 1200 kg/m3, the paper having a ratio of grammage to thickness of the paper in micrometres equal to or higher than 1.0, wherein the grammage refers to the weight of the paper (PAP1) in grams per square meter, the paper (PAP1) comprising cellulose fibres from
- bleached chemical pulp and
- bleached chemithermomechanical pulp (BCTMP),
wherein the bleached chemithermomechanical pulp comprises cellulose fibres from hardwood (HW1) and softwood (SW1).
A method for manufacturing paper (PAP1) suitable for use as a layer of a release liner, the method comprising:
- mixing
o bleached chemical pulp and
o bleached chemithermomechanical pulp (BCTMP) from hardwood (HW1) and softwood (SW1), thereby forming a pulp mixture (MIX1), 
- forming a paper web (WEB1) from the pulp mixture (MIX1),
- reducing moisture content of the paper web (WEB1) in a press section, and
- drying the paper web (WEB1) in a drying section, thereby forming paper (PAP1) having a density equal to or less than 1200 kg/m3, a ratio of grammage to thickness of the paper in micrometres equal to or higher than 1.0, wherein the grammage refers to the weight of the paper (PAP1) in grams per square meter.
The method according to claim 2, further comprising refining the pulp mixture (MIX1), such that after refining, the pulp mixture (MIX1) has
- a Schopper-Riegler value equal to or less than 70, preferably equal to or less than 50, such as in the range of 25 to 55, preferably in the range of 30 to 50, or
- a Canadian Standard Freeness value of equal to or more than 90 ml, preferably equal to or more than 180 ml, such as in the range of 180 to 500 ml, preferably in the range of 215 to 425 ml.
The method according to claim 2 or 3, further comprising refining the bleached chemical pulp and/or the bleached chemithermomechanical pulp prior to forming the pulp mixture (MIX1) such that after refining, the bleached chemical pulp and/or the bleached chemithermomechanical pulp has
- a Canadian Standard Freeness value of equal to or more than of 90 ml, such as in the range of 90 to 500 ml, and the pH of aqueous extracts equal to or above pH 7.0, or
- a Canadian Standard Freeness value equal to or more than 130 ml, such as in the range of 130 to 425 ml, and the pH of aqueous extracts equal to or above pH 7.1, or
- a Canadian Standard Freeness value equal to or more than 325 ml, such as in the range of 325 to 435 ml, and the pH of aqueous extracts equal to or above pH 7.3.
The method according to claim 2, 3 or 4, further comprising calendering the paper (PAP1) after drying.
The paper (PAP1) according to claim 1 or the method according to any of the claims 2 to 5, wherein the layer is a support layer or a substrate layer of the release liner.
The paper (PAP1) or the method according to any of the preceding claims, wherein the bleached chemical pulp comprises hardwood pulp (PULP1), such as bleached pulp from a Kraft process.
The paper (PAP1) or the method according to any of the preceding claims, wherein the bleached chemical pulp comprises both hardwood pulp (PULP1) and softwood pulp (PULP2), such as bleached pulp from a Kraft process.
The paper (PAP1) or the method according to any of the preceding claims, wherein the amount of cellulose fibers from bleached chemithermomechanical pulp in the paper is equal to or less than 50 wt.-% of the weight of the paper, such as in the range of 1 to 50 wt.-%, preferably in the range of 5 to 45 wt.-%, most preferably in the range of 10 to 35 wt.-%.
The paper (PAP1) or the method according to any of the preceding claims, wherein the grammage of the paper is equal to or less than 120 g/m2 preferably equal to or less than 80 g/m2, most preferably equal to or less than 70 g/m2, such as in the range of 30 to 120 g/m2, preferably in the range of 35 to 80 g/m2, most preferably in the range of 50 to 70 g/m2.
The paper (PAP1) or the method according to any of the preceding claims, wherein the density of the paper is less than 1200 kg/m3, preferably in the range of 1000 to 1200 kg/m3, most preferably in the range of 1050 to 1150 kg/m3.
The paper (PAP1) or the method according to any of the preceding claims, wherein the thickness of the paper is equal to or less than 100 micrometres, such as in the range of 35 to 95 micrometres, preferably in the range of 40 to 68 micrometres, most preferably in the range of 45 to 60 micrometres.
The paper (PAP1) or the method according to any of the preceding claims, wherein
- the paper has a transparency level of equal to or higher than 28%, preferably equal to or higher than 33%, such as in the range of 28% to 85%, when the grammage of the paper is equal to or higher than 70 grams per square meter, or
- the paper has a transparency level equal to or higher than 40%, preferably equal to or higher than 60%, such as in the range of 40% to 85%, when the grammage of the paper is less than 70 grams per square meter.
The paper (PAP1) or the method according to any of the preceding claims, wherein the amount of softwood (SW1) in the bleached chemithermomechanical pulp (BCTMP) is in the range of 1 to 50 wt.-%, preferably in the range of 5 to 45 wt.-%, most preferably in the range of 10 to 35 wt.-% of the weight of the bleached chemithermomechanical pulp.
The paper (PAP1) or the method according to any of the preceding claims, wherein the cellulose fibers from softwood (SW1) in the bleached chemithermomechanical pulp are from a coniferous tree, preferably from the genus Picea, Abies, Larix or Pinus, most preferably from spruce, such as Picea abies.
The paper (PAP1) or the method according to any of the preceding claims, wherein the cellulose fibers from hardwood (HW1) in the bleached chemithermomechanical pulp are from aspen or eucalyptus, preferably from the genus Populus or Eucalyptus, such as Populus tremuloides, Populus tremula or Eucalyptus globulus.
The paper (PAP1) or the method according to any of the preceding claims, wherein the paper (PAP1) is glassine paper.
A release liner substrate layer comprising a primer layer applied to a support layer, wherein the support layer is paper (PAP1) according to any of the claims 1 or 6-17.
A release liner comprising a release coating and a primer layer applied to a support layer, wherein the support layer is paper (PAP1) according to any of the claims 1 or 6-17.
Use of a paper (PAP1) according to any of the claims 1 or 6-17 as a release liner support layer.
Use of a paper (PAP1) according to any of the claims 1 or 6-17 in combination with a release coating.
Ref WO2020084188A1: Claims:
1. A backing material layer (PAP1 ) for a release liner (REL1 ),
wherein the backing material layer (PAP1 ) comprises:
- bleached chemical pulp (PULPV1 ), and
- bleached recycled release liner pulp (BRELP1 )
wherein
- lightness L* of the backing material layer (PAP1 ) is at least 90,
- color channel b* of the backing material layer (PAP1 ) is between 2 and 12, - color channel a* of the backing material layer (PAP1 ) is between -7 and
+3, and
- amount of the bleached recycled release liner pulp (BRELP1 ) is at least 1 wt.-% based on the total weight of said backing material layer (PAP1 ), and
- the backing material layer (PAP1 ) has a grammage equal to or higher than 30 grams per square meter.
2. The backing material layer according to claim 1 , wherein the backing material layer (PAP1 ) has silicone content less than 2.0 wt.-%.
3. The backing material layer according to claim 1 or 2, wherein the bleached recycled release liner pulp has silicone content between 0 and 1.0 wt.-%,
4. The backing material layer according to any of the preceding claims, wherein the color channel a* of the backing material layer (PAP1 ) is between -5 and +1.
5. The backing material layer according to any of the preceding claims, wherein the color channel b* of the backing material layer (PAP1 ) is between 4 and 10.
6. The backing material layer according to any of the preceding claims, wherein the amount of the bleached recycled pulp is at least 5 wt.-% based on the total weight of said backing material layer (PAP1 ).
. The backing material layer according to any of the preceding claims, wherein the lightness L* of the backing material layer (PAP1 ) is at least 92.
7. The backing material layer according to any of the preceding claims, wherein the backing material layer (PAP1 ) comprises a coating on the paper (PAP2).
8. The backing material layer according to any of the preceding claims, wherein the amount of the bleached recycled release liner pulp is between 7 wt.-% and 25 wt.-% calculated from the total weight of the backing material layer.
9. The backing material layer according to any of the preceding claims, wherein amount of mechanical pulp is less than 5 wt.-% calculated from the total weight of the backing material layer (PAP1 )
10. The backing material layer according to any of the preceding claims, wherein total amount of mineral fillers in the backing material layer is less than 12 wt.-% based on the total weight of the backing material layer (PAP1 ).
11. A release liner comprising
- the backing material layer (PAP1 ) according to any of the preceding claims 1 to 10, and
- a release coating layer (RELCT1 ) on said backing material layer.
12. A label laminate comprising
- the release liner (REL1 ) according to the claim 11 , and
- a face layer (FACE1 ),
wherein an adhesive layer (ADH1 ) is provided between the release liner (REL1 ) and the face layer (FACE1 ).
13. A method for manufacturing a backing material layer (PAP1 ) suitable for use as a layer of a release liner (REL1 ),
the method comprising: 

 - forming a pulp mixture (MIX1 ) comprising cellulose fibers by mixing at least bleached chemical pulp (PULPV1 ) and bleached recycled release liner pulp (BRELP1 ),
- forming a paper web from the pulp mixture (MIX1 ),
- reducing moisture content of the paper web hereby forming paper (PAP2) for the backing material layer (PAP1 ), and
- treating the paper (PAP2) in order to form the backing material layer (PAP1 )
wherein
- the formed backing material layer (PAP1 ) has a grammage equal to or higher than 30 grams per square meter,
- lightness L* of said backing material layer (PAP1 ) is at least 90,
- color channel b* of said backing material layer (PAP1 ) is between 2 and 12, and
- color channel a* of said backing material layer (PAP1 ) is between -7 and +3, and
- amount of the bleached recycled release liner pulp (BRELP1 ) is at least 1 wt.-% based on the total weight of said backing material layer (PAP1 ).
14. The method according to claim 13, comprising
- bleaching the recycled release liner pulp (RELP1 ) in order to form bleached recycled release liner pulp (BRELP1 ) before forming the pulp mixture (MIX1 ).
15. The method according to claim 14, wherein the recycled release liner pulp is bleached by using at least one of the following chemicals:
- hydrogen peroxide H2O2,
- sodium dithionite Na2S204,
- sodium bisulfite NaHSOs, and
- sodium borohydride solution.
16. The method according to claim 15, wherein the recycled release liner pulp is bleached by using sodium dithionite Na2S204 and the amount of the sodium dithionite is between 0.15 and 0.50 wt.-% calculated from dry weight of the recycled release liner pulp.
17. The method according to any of the preceding claims 13 to 16, wherein the bleached recycled release liner pulp has silicone content between 0 and 1.0 wt.-%,
18. The method according to any of the preceding claims 13 to 17, wherein the color channel a* of the backing material layer (PAP1 ) is between -5 and +1 , and the color channel b* of the backing material layer (PAP1 ) is between 4 and 10.
19. The method according to any of the preceding claims 13 to 18, wherein the treatment for the paper (PAP2) comprises
- coating the paper (PAP2).
20. The method according to any of the preceding claims 13 to 19, wherein the amount of the dosed bleached recycled release liner pulp is between 7 wt.-% and 25 wt.-% calculated from the total weight of the backing material layer (PAP1 ).
21. The method according to any of the preceding claims 13 to 20, wherein amount of mechanical pulp is less than 5 wt.-% calculated from the total weight of the backing material layer (PAP1 ) and total amount of mineral fillers in the backing material layer is less than 12 wt.-% based on the total weight of the backing material layer (PAP1 ).
22. Use of a backing material layer (PAP1 ) according to any of the claims 1 10 in combination with a release coating.
23. A method for manufacturing recycled release liner pulp suitable for use as a raw material in a layer of a release liner, the method comprising:
- pulping recovered release liner material in water-based solution in order to release at least some silicone particles to said water-based solution,
- removing at least some of said silicone particles from the water-based solution by using a flotation step,
- removing at least some impurities from the pulped release liner material in a screening step and/or a cleaning step, and 

 - removing at least some water from said pulped release liner material in order to form recycled release liner pulp (RELP1 ).
24. The method according to claim 23, wherein the method further comprises - bleaching the recycled release liner pulp in order to form bleached recycled release liner pulp (BRELP1 ).