Shoe Press Roll Sleeve
Patent Information
- Application Number
- JP2024519043
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2021-09-28
- Filing Date
- 2022-09-13
- Publication Date
- 2025-08-22
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing shoe press roll sleeves in the paper industry are made primarily from petroleum-based polyurethane, leading to significant environmental impact due to thermal recycling or incineration, and there is a need for improved mechanical properties and reduced carbon footprint.
Developing shoe press roll sleeves with at least 20% biobased polyurethane matrix material using biobased polyols and crosslinkers, such as PTMEG, MCDEA, polycarbonate polyol, and 1,4-BDO, to enhance mechanical properties and reduce carbon emissions.
The biobased polyurethane sleeves exhibit improved mechanical properties, such as crack resistance, tear propagation, and reduced carbon emissions, while maintaining operational efficiency.
Abstract
Description
[Technical field]
[0001] The present invention relates to a shoe press roll sleeve for a machine for producing and / or finishing fibrous webs, such as paper, cardboard or tissue webs, comprising a polyurethane matrix material substantially formed from 4,4'-MDI as isocyanate, at least one polyol and at least one crosslinking agent. The present invention also relates to a shoe press comprising said shoe press roll sleeve, and a machine for producing and / or finishing fibrous webs comprising said shoe press.
[0002] Shoe press roll sleeves of this type are known, for example, from EP 2 248 944 A1.
[0003] In this context, the term "substantially" means that the polyurethane matrix material may also contain small amounts of other materials, such as small amounts of catalyst for or in at least one crosslinker, in addition to the starting materials mentioned, but these other materials advantageously account for less than 8% by weight of the total starting materials, more preferably less than 5% by weight, even more preferably less than 2% by weight.
[0004] Shoe presses have many applications in the paper industry. For example, they can be used to transfer tissue webs from press felts to the surface of Yankee cylinders. Shoe presses are particularly characterized by their extended press nip, which allows the fibrous web to be pressed efficiently without subjecting it to high peak pressures that would otherwise adversely affect its thickness.
[0005] In order to be able to achieve an extended press nip, in addition to the roll, a shoe is required which can be pressed against the roll and whose surface has a concave curvature adapted to the curvature of the roll. In normal operation, the rotating shoe press roll sleeve is guided above the shoe. It is a continuous tube and must be made sufficiently flexible to be able to withstand the constant alternating bending loads between concave and convex curvatures during rotation. The shoe press roll sleeve is exposed to very high stresses during normal use, which cause wear and therefore require regular replacement.
[0006] Known shoe press roll sleeves are mainly made of polyurethane, which usually forms a matrix material in which reinforcing threads etc. are embedded. The amount of polyurethane thus consumed is quite large. After use, the shoe press roll sleeves are usually thermally utilized or incinerated, which is not optimal from the point of view of environmental protection.
[0007] Efforts have also been made to further improve the known shoe press sleeves with respect to various properties important for their use as a matrix material for shoe press roll sleeves, which may in particular be one or more of the following properties: crack resistance (crack propagation), tear propagation resistance, tan delta, force at 10% elongation after hydrolysis, stress at break, elongation at break, abrasion resistance, and weight gain on storage in a liquid medium.
[0008] The object of the present invention is therefore to address the above-mentioned problems, in particular to contribute to decarbonization, while at the same time not adversely affecting and advantageously even improving the operationally relevant properties of the shoe press roll sleeve.
[0009] The object of the present invention is to provide a shoe press roll sleeve of the type mentioned at the beginning, in which at least 20% by weight of the polyurethane matrix material is biobased, at least one polyol and at least one crosslinker are selected from the group consisting of: a) PTMEG as polyol and a mixture of MCDEA and PTMEG as crosslinker, where the PTMEG in the polyol and crosslinker is bio-based; b) polycarbonate as polyol and a mixture of MCDEA and polycarbonate polyol as crosslinker, where the polycarbonate polyol in the crosslinker is bio-based; c) a mixture of polycarbonate polyol and PTMEG as polyol and 1,4-BDO as crosslinker, where the polycarbonate polyol in the polyol is bio-based; d) PTMEG as polyol and a mixture of PTMEG and MCDEA as crosslinker, where 4,4'-MDI in the isocyanate and PTMEG in the polyol are bio-based. The problem is solved by selecting one of the combinations:
[0010] Here, the term "bio-based" means that the material is made from renewable, non-petroleum-based feedstocks. The finished product according to the invention is made from what percentage of the carbon in the material is 14 It can be distinguished from conventional shoe press sleeves because it can be determined by radiocarbon dating whether it is the C isotope type. This carbon isotope is unstable in that it undergoes radioactive decay. It is therefore almost absent in petroleum. It is therefore relatively easy to determine the percentage of biobased carbon atoms in relation to the total percentage of carbon atoms in the material, for example using standardized test methods according to ASTM D6866.
[0011] The production of polyurethanes from at least partially bio-based starting materials is already known per se, but this has not yet been specifically considered for shoe press roll sleeves. For example, WO 2021 / 074492 describes that roll covers can be produced from recycled starting materials and, optionally, from bio-based starting materials. Surprisingly, the inventors have found that not only can shoe press roll sleeves be produced based on bio-based starting materials of the polyurethane matrix, which have mechanical properties comparable or identical to those of conventional petroleum-based starting materials, but also, at least for some special compositions, the mechanical properties of the shoe press sleeve can be improved. The exact reasons for this are not yet clear, but tests have given clear results on this matter.
[0012] Thus, the invention not only makes it possible to improve the CO balance in the production of shoe press roll sleeves, since the CO released during incineration of the shoe press roll sleeves is at least partially reabsorbed by the plant and then used for the production of new shoe press roll sleeves, the invention furthermore also offers the possibility of positively influencing the mechanical properties of the shoe press roll sleeve according to the invention.
[0013] Advantageously, at least 50% by weight of the polyurethane matrix material is bio-based. It is furthermore conceivable to manufacture the shoe press sleeve entirely from bio-based starting materials.
[0014] In this case, the 4,4'-MDI as the isocyanate in the polyurethane matrix material can be petroleum-based unless expressly designated as bio-based according to the present invention.
[0015] At least one polyol in the polyurethane matrix material may also be petroleum-based, unless expressly specified as bio-based in accordance with the present invention.
[0016] Additionally, at least one crosslinker in the polyurethane matrix material may also be petroleum-based, unless expressly specified as bio-based in accordance with the present invention.
[0017] Below, starting materials that are not explicitly stated to be bio-based are assumed to be oil-based.
[0018] In a first specific embodiment example of the polyurethane matrix composition of the shoe press sleeve according to the present invention, it is provided that the polyurethane of the polymer matrix is formed from 4,4'-MDI as an isocyanate, PTMEG as a polyol, and a mixture of MCDEA and PTMEG as a crosslinking agent, and the PTMEG in the polyol and crosslinking agent is bio-based, where MCDEA stands for 4,4'-methylenebis-(3-chloro-2,6-diethylaniline).
[0019] Below, this composition (last row of Table 1A) is compared to a corresponding composition comprised purely of petroleum-based starting materials (penultimate row of Table 1A).
[0020] [Table 1]
[0021] Examination of the corresponding cast samples revealed that the polyurethane produced from the bio-based starting material (last row of Table 1B) differed favorably from the corresponding comparative material produced from a petroleum-based matrix material (penultimate row of Table 1B) with respect to various properties important for use as a matrix material for shoe press roll sleeves.
[0022] [Table 2]
[0023] The property "crack propagation [mm]" is the result of testing a standardized sample by making a targeted notch and then bending it at the notch position using a testing device for 1 million cycles. The extent to which the crack propagates at the notch position is then measured. The smaller this value, the more suitable the polyurethane is as a matrix material for shoe press roll sleeves. In the first example embodiment, it can be seen that the crack does not propagate at all in the bio-based polyurethane, whereas it propagates 0.6 mm in the petroleum-based polyurethane.
[0024] "Tear propagation resistance" is the result of a test described in standard DIN 53515, which measures the force with which a scored sample resists tear propagation. In this case, the area under the curve (or integral) of the stress-strain diagram, which corresponds to the energy, can also be determined. The higher the respective values, the more suitable the polyurethane is as a matrix material for shoe press roll sleeves. In the first embodiment example, it can be seen that the values of the sample made from bio-based polyurethane are higher than those of a comparative sample made from petroleum-based polyurethane.
[0025] The property "tan delta" in rheology is the loss factor, which is the ratio of the loss modulus G'' (imaginary part) to the storage modulus G' (real part), expressed as tan delta = G'' / G'. The higher the loss factor, the closer the sample's behavior is to that of an ideal viscous liquid with Newtonian fluid behavior. The lower the loss factor, the more the sample's behavior matches that of an ideal elastic solid, the latter being desirable for a shoe press roll sleeve matrix material. In the first example embodiment, it can be seen that the bio-based polyurethane has a lower tan delta value than the corresponding petroleum-based polyurethane at both 20°C and 60°C.
[0026] In a second specific embodiment of the polyurethane matrix composition of the shoe press sleeve according to the present invention, it is provided that the polyurethane of the polymer matrix is formed from 4,4'-MDI as an isocyanate, polycarbonate as a polyol, and a mixture of MCDEA and polycarbonate polyol as a crosslinker, and the polycarbonate polyol in the crosslinker is bio-based.
[0027] Below, this composition (last row of Table 2A) is compared to a corresponding composition comprised purely of petroleum-based starting materials (penultimate row of Table 2A).
[0028] [Table 3]
[0029] Examination of the corresponding cast samples revealed that the polyurethane made from bio-based starting materials (last row of Table 2B) differed favorably from the corresponding comparative material made from a petroleum-based matrix material (penultimate row of Table 2B) with respect to various properties important for use as a matrix material for shoe press roll sleeves.
[0030] [Table 4]
[0031] The second example embodiment also shows that the polyurethane samples containing bio-based components have lower tan delta values at both 20° C. and 60° C., and are therefore superior, to the corresponding comparison samples composed purely of petroleum-based components.
[0032] The properties "H2O swell" and "H2O2 swell" are the weight gain percentages when the sample material is immersed in water or hydrogen peroxide for a long time. The lower the swelling, the more suitable the polyurethane is as a matrix material for shoe press roll sleeves. In the second example embodiment, it can be seen that the corresponding values are lower for the sample made from bio-based polyurethane than for the comparative sample made from petroleum-based polyurethane.
[0033] The property "force at 10% elongation after hydrolysis" in the stress-strain diagram is the force required to elongate the sample by 10% after the sample has been subjected to hydrolysis. More precisely, a value of, for example, 73% means that the force required for 10% elongation after hydrolysis is only 73% of the force required before hydrolysis. The higher this value, the more suitable the polyurethane is as a matrix material for shoe press roll sleeves. In the second example embodiment, it can be seen that the corresponding value is higher for the sample made from bio-based polyurethane than for the comparative sample made from petroleum-based polyurethane.
[0034] The properties "stress at break" and "elongation at break" are the results of standardized tensile tests well known to those skilled in the art. The higher these values, the more suitable the polyurethane is as a matrix material for shoe press roll sleeves. In the second example embodiment, it can be seen that the corresponding values are higher for the samples made from bio-based polyurethane than for the comparative samples made from petroleum-based polyurethane.
[0035] In a third specific embodiment of the polyurethane matrix composition of the shoe press sleeve according to the present invention, it is provided that the polyurethane of the polymer matrix is formed from 4,4'-MDI as an isocyanate, a mixture of polycarbonate polyol and PTMEG as a polyol, and 1,4-BDO as a crosslinking agent, in which the polycarbonate polyol in the polyol is bio-based, where 1,4-BDO stands for 1,4-butanediol.
[0036] Below, this composition (last row of Table 3A) is compared to a corresponding composition made from a purely petroleum-based starting material (penultimate row of Table 3A).
[0037] [Table 5]
[0038] Examination of the corresponding cast samples revealed that the polyurethane made from the bio-based starting material (last row of Table 3B) differed favorably from the corresponding comparative material made from a petroleum-based matrix material (penultimate row of Table 3B) with respect to various properties important for use as a matrix material for shoe press roll sleeves.
[0039] [Table 6]
[0040] In the third embodiment example, it can be seen that the H2O2 swelling value of the sample made from the bio-based polyurethane is lower than that of the comparative sample made from the petroleum-based polyurethane, but all other values are higher than the corresponding values of the comparative sample. Therefore, except for the crack propagation property, the sample made from the bio-based polyurethane is more suitable for use as a matrix material for shoe press roll sleeves than the comparative sample.
[0041] In a fourth specific embodiment of the polyurethane matrix composition of the shoe press sleeve according to the present invention, it is provided that the polyurethane of the polymer matrix is formed from 4,4'-MDI as an isocyanate, PTMEG as a polyol, and a mixture of PTMEG and MCDEA as crosslinkers, and that the 4,4'-MDI in the isocyanate and the PTMEG in the polyol are bio-based.
[0042] Below, this composition (last row of Table 4A) is compared to a corresponding composition made from a purely petroleum-based starting material (penultimate row of Table 4A).
[0043] [Table 7]
[0044] Examination of the corresponding cast samples revealed that the polyurethane made from the bio-based starting material (last row of Table 4B) differed favorably from the corresponding comparative material made from a petroleum-based matrix material (penultimate row of Table 4B) with respect to various properties important for use as a matrix material for shoe press roll sleeves.
[0045] [Table 8]
[0046] In the fourth example embodiment, it can be seen that the break stress value is higher for the sample made from the bio-based polyurethane than for the comparative sample made from the petroleum-based polyurethane, but the H2O2 weight gain value, the H2O weight gain value, and the tan delta values at 20° C. and 60° C. are lower than the corresponding values for the comparative sample. Thus, the sample made from the bio-based polyurethane is more suitable for use as a matrix material for shoe press roll sleeves than the comparative sample with respect to all these values.
[0047] The "abrasion value" property is the result of a test that measures the degree of abrasion that a sample material undergoes under standardized conditions. The lower this value, the more suitable the polyurethane is as a matrix material for shoe press roll sleeves. In the fourth embodiment example, the abrasion value is indeed higher in the sample made from bio-based polyurethane than in the comparative sample made from petroleum-based polyurethane, but this value increases much less after hydrolysis than in the comparative sample, which is favorable.
[0048] Further aspects of the present invention relate to a machine for the production and / or finishing of fibrous webs, such as paper, cardboard or tissue webs, which is equipped with a shoe press roll sleeve according to the invention as described above, and to a machine for the production and / or finishing of fibrous webs, such as paper, cardboard or tissue webs, which is equipped with such a shoe press.
Claims
1. A shoe press roll sleeve for a machine for producing and / or finishing a fibrous web, such as a paper web, a cardboard web or a tissue web, comprising a polyurethane matrix material substantially formed from 4,4'-MDI as an isocyanate, at least one polyol and at least one crosslinking agent, At least 20% by weight of the polyurethane matrix material is bio-based, and the at least one polyol and the at least one crosslinker are selected from the following: a) PTMEG as a polyol and a mixture of MCDEA and PTMEG as a crosslinker, wherein the PTMEG in the polyol and the crosslinker is bio-based; b) polycarbonate as polyol and a mixture of MCDEA and polycarbonate polyol as crosslinker, wherein said polycarbonate polyol in said crosslinker is bio-based; c) a mixture of polycarbonate polyol and PTMEG as polyol and 1,4-BDO as crosslinker, wherein the polycarbonate polyol in the polyol is bio-based; d) PTMEG as polyol and a mixture of PTMEG and MCDEA as crosslinker, wherein the 4,4'-MDI in the isocyanate and the PTMEG in the polyol are bio-based. A shoe press roll sleeve characterized in that the combination of the above is selected from one of the above.
2. The shoe press roll sleeve of claim 1 , wherein at least 50% by weight of the polyurethane matrix material is bio-based.
3. The shoe press roll sleeve according to claim 1, characterized in that the 4,4'-MDI as the isocyanate in the polyurethane matrix material is petroleum-based unless otherwise stated as bio-based in claim 1.
4. 2. The shoe press roll sleeve of claim 1, wherein the at least one polyol in the polyurethane matrix material is petroleum-based unless otherwise specified in claim 1 as bio-based.
5. 2. The shoe press roll sleeve of claim 1, wherein the at least one crosslinking agent in the polyurethane matrix material is petroleum-based unless otherwise specified in claim 1 as bio-based.
6. 6. A shoe press of a machine for producing and / or finishing fibrous webs, such as paper webs, cardboard webs or tissue webs, comprising a shoe press roll sleeve according to any one of claims 1 to 5.
7. 7. A machine for producing and / or finishing fibrous webs, such as paper webs, cardboard webs or tissue webs, comprising a shoe press according to claim 6.