RU2796735C2 - Method for manufacturing a block from polyurethane/polyisocyanurate foam plate for thermal insulation of a tank - Google Patents

Abstract

FIELD: chemical industry.

SUBSTANCE: invention relates to a method for producing reinforced polyurethane foam products, in particular a block of fibre-reinforced polyurethane/polyisocyanurate foam for boards used in thermal insulation tanks. The density of such blocks is less than 50 kg⋅m^-3 with a C_f fibre content of at least 4% by weight of the fibre-reinforced foam block. The process of obtaining a block includes: mixing the components necessary to obtain a polyurethane/polyisocyanurate foam; impregnation of the fibre with the resulting mixture under the action of a gravitational flow, expansion of the foam, which is limited by the walls of the two-belt laminator. Moreover, the mentioned fibres have a length of at least five centimetres and are located in layers superimposed on each other. The mixture of chemical components has a dynamic viscosity during the impregnation step, so that the impregnation time t_i of the fibres is less than the creaming time t_c of the polyurethane/polyisocyanurate foam.

EFFECT: method described makes it possible to obtain fibre-reinforced low density polyurethane and/or polyisocyanurate foam blocks having good mechanical properties.

21 cl, 4 dwg, 4 tbl, 1 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] The object of the present invention is a method of manufacturing blocks of fiber reinforced polyurethane (PUR, PUR) and / or polyisocyanurate (PIR, PIC) foam (containing fibers from long to continuous) from at least one polyisocyanate and at least one polyol, wherein said foam blocks are used in a tank built into a load-bearing or self-supporting structure type B or C, serving to receive very cold fluids, called cryogenic fluids, for example, in particular, liquefied natural gas (LNG) or liquefied petroleum gas (LHG ).

[0002] The present invention also relates to fiber-reinforced polyurethane and/or polyisocyanurate foam blocks, which, given their particular application, must have specific mechanical and thermal characteristics, while at the same time their manufacture must be as cost effective as possible.

[0003] Finally, the present invention particularly relates to sealed and insulated tanks using such foam obtained directly according to the manufacturing process, as well as ships equipped with such tanks.

BACKGROUND OF THE INVENTION

[0004] Polyurethane (PUR) foam is a cellular insulator consisting of small cells that store a gas that may have a low thermal conductivity. Polyurethane foam is used in many applications, for example in the automotive industry as flexible polyurethane foam or in thermal insulation as rigid polyurethane foam. The preparation of polyurethane foam is well known to the person skilled in the art. The preparation involves a multicomponent reaction between a polyol (a compound containing at least two hydroxyl groups), a polyisocyanate (a compound containing at least two isocyanate functional groups -NCO) and an expanding agent, also known as a "foaming agent". The condensation reaction is in particular catalyzed by compounds of a basic and/or nucleophilic nature, for example tertiary amines or metal carboxylate coordination complexes, for example tin or bismuth salts. Polyols commonly used in the manufacture of polyurethane foam are polyether polyols or polyester polyols. Thus, a large number of compounds are required to produce polyurethane foam.

[0005] Polyisocyanurate (PIC) and polyurethane/polyisocyanurate (PUR-PIC) foam is also used in the construction sector (construction/renovation) and has the advantage of providing better fire resistance as well as higher compressive strength than polyurethane foam. The method for producing such a foam is similar to the method for producing polyurethane foam. In fact, the production of polyurethane, polyisocyanurate and polyurethane/polyisocyanurate foam depends on the ratio of isocyanate and polyol.

[0006] Documents FR 2 882 755 and KR 20000010021 are known in the art and describe fiber-reinforced polyurethane or polyisocyanurate foam and its manufacture. In these documents, the polyurethane or polyisocyanurate foam has a high density.

[0007] The preparation of polyurethane, polyisocyanurate, and polyurethane/polyisocyanurate foam is well known to those skilled in the art; however, the addition of fibers entails specific technical problems, in particular if it is necessary to obtain a fiber-reinforced polyurethane, polyisocyanurate or polyurethane/polyisocyanurate foam, in the volume of which the fibers are uniformly distributed from long to continuous, i.e. at least five centimeters long.

[0008] In particular, in the case where low-density fiber-reinforced polyurethane, polyisocyanurate and polyurethane/polyisocyanurate foam, that is, foam having a density of less than 50 kg⋅m ^-3 , is to be obtained, the addition of fibers is extremely difficult and generally results in to the formation of foam with non-uniformly distributed fibers. This is due to the fact that in order to obtain a low density fiber-reinforced foam, it is necessary to simultaneously carry out a rapid and uniform impregnation of the fibers using a large amount of blowing agent. This results in the blowing agent not being completely dissolved in the polyol and subsequently forming an emulsion of the blowing agent in the rich polyol, which must be stabilized and effectively mixed with the isocyanate. In the context of casting (by gravity) a mixture of prepolymers onto fibers, one solution to this problem is to increase the amount of nucleating gas during mixing of the polyol and isocyanate, which increases the viscosity and makes it difficult or impossible for the polyurethane/polyisocyanurate foam to penetrate properly into the fibers and therefore , obtaining a block of homogeneous fiber-reinforced foam, and the upper parts of the block do not contain or practically do not contain fibers.

[0009] Thus, an increase in the amount of blowing agent leads to the formation of a foam of non-uniform structure or density (in terms of fibers), and the fiber-reinforced foam thus obtained is ineffective in terms of thermal insulation and has poor mechanical properties.

[0010] In addition, increasing the amount of blowing agent requires the use of more reactive chemicals to compensate for the endothermic phenomena associated with significant evaporation of the physical blowing agent, which reduces the time to creamy mass and does not allow the fibers to be well saturated for their controlled expansion.

[0011] An additional problem is the production of a cost-effective foam block, i.e. a block that does not need to be cut to obtain a block of uniform fiber-reinforced foam, since material losses associated with cutting are usually on the order of 15% or even more than 20%, which is absolutely unacceptable for industrial production.

[0012] Thus, at present, there is no way to produce a block of fiber-reinforced polyurethane and/or polyisocyanurate foam of low density (less than 50 kg m ^-3 ), which allows to obtain a block having very good mechanical properties, in particular, due to inhomogeneity of fibers in the block.

SUMMARY OF THE INVENTION

[0013] It is in this context that the Applicant has succeeded in developing a process for the manufacture of polyurethane (PUR) and/or polyisocyanurate (PIC) foam containing long to continuous fibers in a significant amount, which makes it possible to obtain an easy-to-handle fiber-reinforced foam having excellent mechanical properties, and maintain or even improve the excellent thermal insulation performance. Preferably, according to the preferred embodiment, it is also possible to significantly reduce the production costs of fiber-reinforced foam due to the ideal uniformity of the latter (hence the loss of material of the foam block is minimal or negligible).

[0014] The expression "block" in accordance with the invention is a non-limiting expression. The "block" can be any shape and doesn't have to be cut out.

[0015] Thus, the present invention addresses the shortcomings of the prior art by providing a particularly efficient and easy-to-implement solution for industrial production of fiber-reinforced polyurethane/polyisocyanurate low density foam with optimal mechanical properties.

[0016] After conducting various studies and analyzes, the Applicant has found that the manufacture of a block of fiber reinforced polyurethane (PUR) and/or polyisocyanurate (PIC) foam using long to continuous fibers can solve the technical problems of existing manufacturing methods, taking into account specific goals related to with the final application of a block of low density foam.

[0017] Thus, the present invention relates to a method for manufacturing a fiber-reinforced polyurethane/polyisocyanurate foam block for a thermal insulation board of a sealed and thermally insulated tank, wherein the fiber-reinforced polyurethane/polyisocyanurate foam block consists of cells storing a gas, preferably having a low thermal conductivity, and has a density of less than 50 kg⋅m ^-3 with a C _f fiber content of at least 4% by weight of the fiber reinforced foam block, the manufacturing method comprising the following steps:

a) a step in which the chemical components necessary to obtain a polyurethane/polyisocyanurate foam are mixed, and said components contain reagents for the production of polyurethane/polyisocyanurate, additionally at least one reaction catalyst, additionally at least one emulsifier and, according to at least one blowing agent,

b) a step in which a plurality of fibrous reinforcing materials are impregnated under the action of the gravitational flow of the aforementioned mixture of chemical components, said fibers being long to continuous fibers and arranged in superimposed layers, in which the fibrous reinforcing materials extend essentially in a direction perpendicular to in the direction of said gravitational flow, moreover, the fibrous reinforcing materials have a permeability K _c with respect to the above mixture of chemical components, expressed in m ² , equal to:

K _c = (r _f ² × p ³ )/(k × τ ² × 4 × V _f ² ), where

r _f is the radius of the fibers, expressed in meters (m),

p is the porosity of the fibers (dimensionless value), has a value from 0 to 1,

k is the form factor (dimensionless value) depending on the nature of the fibers,

τ - crimp (dimensionless value) depending on the location of the fibers,

V _f is the volume fraction of fibers (the fraction of fibers in the volume of the reinforcing material), which takes a value from 0 to 1 with the exception of 0,

c) a step in which the fiber-reinforced polyurethane/polyisocyanurate foam is formed and expanded.

[0018] The process according to the invention is characterized in that the aforementioned mixture of chemical components has a dynamic viscosity η in the impregnation step b), so that the impregnation time t _i of the fibers is less than the creaming time t _c of the polyurethane/polyisocyanurate foam, wherein the time t _i impregnation of fibers is equal to:

t _i = (η × _em ² )/(K _c × ∆P),

ΔP = (M _sd × g _T × k _p ), where

η is the dynamic viscosity expressed in pascal⋅seconds (Pa⋅s),

e _m is the sum of the average thicknesses of the fibrous reinforcing materials, expressed in meters (m),

ΔP is the hydraulic pressure gradient or differential, expressed in pascals (Pa),

M _sd is the surface density of the above mixture of chemical components, expressed as mass per unit area (kg⋅m ^-2 ),

g _T - the force of the earth's gravity, in this case it is considered equal to 9.8 N⋅kg ^-1 ,

k _p is the average coefficient of hydraulic pressure, a constant equal to 0.5.

[0019] By "gas storage cells" it is to be understood that the polyurethane/polyisocyanurate foam has closed cells enclosing a gas, preferably having a low thermal conductivity, obtained from the gas introduced during the nucleation step of the reaction mixture, or obtained directly or indirectly based on a chemical or physical expanding agent.

[0020] By "fibrous reinforcing material" it is to be understood that the fibers can be provided in two different forms:

or in the form of at least one web of fibers in which the fibers are perfectly aligned in at least one direction, in other words, the fibers have at least one predominant fiber direction. The expression "fabric of fibers" essentially refers to a clear technical definition known to a person skilled in the art,

or in the form of at least one mat of fibers in which the fibers do not have any particular orientation, in other words, the fibers are oriented isotropically substantially along the main plane of the mat layer. Again, the expression "fiber mat" essentially refers to a well-defined technical definition known to a person skilled in the art.

[0021] In accordance with one embodiment, the expression "gas, (preferably) having low thermal conductivity" is to be understood as a gas obtained on the basis of a blowing agent, or as a result of a chemical reaction of the latter, when this agent is considered "chemical", usually it is dioxide carbon (CO ₂ ) when the chemical blowing agent consists of water, or by a physical blowing agent such as, for example, molecular nitrogen (N ₂ ), molecular oxygen (O ₂ ), carbon dioxide, hydrocarbons, chlorofluorocarbons, hydrochlorocarbons, hydrofluorocarbons , hydrochlorofluorocarbons and mixtures thereof. Physical blowing agents, such as molecular nitrogen N ₂ , molecular oxygen O ₂ or CO ₂ are in the form of gases. The gases are distributed in the liquid mass of the copolymer, for example, at high pressure using a static mixer. With a decrease in pressure in the system, nucleation and bubble growth create a cellular structure.

[0022] Under the expression "fibrous reinforcing materials are extended essentially in the direction perpendicular to the direction of the gravitational flow of the mixture of chemical components" it is necessary to understand that the fibrous reinforcing materials are presented in the form of a layer of small thickness, extended in step b) of impregnation along a plane perpendicular to the direction of flow of the said mixtures of components. Thus, as seen in FIG. 1, a plurality of fibrous reinforcing materials having a width L and arranged in superimposed layers move in the longitudinal direction l while the mixture of chemical components is supplied to the fibrous reinforcing materials from a distributor providing a gravitational flow of the mixture of chemical components. In other words, the mixture of chemical components, additionally leaving the distributor under pressure, under the action of at least its own weight, falls on the superimposed mats of fibers, thus impregnating the fibrous reinforcing materials from the upper layer to the lower layer.

[0023] The term "r _f ", referring to the radius of the fibers, expressed in meters (m), must be understood as the radius of the fiber in the reinforcing material, or, more traditionally, the radius or quasi-radius considered in the case of agglomeration of a group of fibers locally forming an agglomerated fiber, having an average radius equivalent to r _f . The data relating to the radius r _f of the fibers is determined by the fibrous reinforcing material, as one of its main physical and chemical characteristics, and, in addition, can be characterized by the linear density (g / kg) or tex, the measurement of the number (linear density) of the yarn, good known to the person skilled in the art, from which the radius r _f of the fibers is obtained, optionally the average radius r _f in the case of fiber agglomeration.

[0024] In other words, the fiber radius r _f is equal to the fiber radius in the reinforcing material if the fiber is not part of an agglomerated fiber, or the agglomerated fiber radius if multiple fibers are agglomerated.

[0025] The term "fibers from long to continuous" is to be understood as meaning that the fibers or, if applicable, agglomerated fibers (fibers glued or bonded together) contain at least 90% of the fibers, considered individually or as agglomerated fibers. , forming the equivalent of one fiber, from the total mass of said fibers, which are at least five (5) centimeters (cm) long.

[0026] In the same way, the porosity p of the fibers as well as the crimp τ are quantitative characteristics of the considered fibrous reinforcing material, that is, the values of these quantitative characteristics are known to define the fibrous reinforcing material. Thus, these values are usually given as defining a fibrous reinforcing material, but, of course, they can be measured using conventional techniques, such as measuring non-vortex stationary flow, unidirectional or radial, calibrated fluid (for example, air, silicone oil) through a certain a pack of fiberglass reinforcing materials using Darcy's law.

[0027] To measure the porosity of the fibers used in the context of the present invention, regardless of whether they are in the form of a fabric of fibers or a mat of fibers, you can, for example, use a caliper, ideally digital, measuring the thickness of a sample pack, for example, out of about ten fabrics or fiber mats used. Knowing the width/length of the fabric sample/mat of fibers and knowing the density (of glass, basalt, carbon, hemp, etc.) of the fibers in question, measure the thickness (or height) at several points/locations of the pack of fabrics of fibers or mats of fibers, forming thickness extremes, to determine the average thickness of the considered fibrous reinforcing material (fabric or mat) and, therefore, to determine the volume occupied by the fibers in the fabric of fibers or mat of fibers (the air density in this case is considered to be zero). As stated above, porosity is a dimensionless quantity with a value between 0 and 1, that is, it indicates the percentage or proportion of voids in the fibrous reinforcing material (fabric or mat) in question, in other words, "fiber porosity".

[0028] It should be noted that the density of the fibers is a property known or available to a person skilled in the art. In general, it is understood that the object of the present invention uses materials/products available or on the market, so that their properties, in particular properties related to density or (dynamic) viscosity, are available in the specifications relating to the materials/products in question.

[0029] The crimp τ of the fibrous reinforcing material corresponds to the average crimp of the fibers that form the fibrous reinforcing material, with the fiber crimp equal to the ratio Le/L, where:

Le: effective path length, that is, the length of the curve formed by the fiber;

L: surface distance at which the fiber is deformed, i.e. the distance between the two ends of the fiber.

[0030] A method for determining fiber crimp or fiber agglomeration (referred to above as "agglomerated fiber") is described, in particular, in R. Pomeroy (2009), "Permeability characterization of continuous filament mats for resin transfer molding", available at in particular, in the Semantic Scholar database.

[0031] Also, the form factor k is a constant determined by the nature of the fibrous reinforcing material in question. Thus, as discussed above, in the context of the present invention, the fibrous reinforcing material may consist of a fabric of fibers or a mat of fibers, with the value of the form factor k being given in each of two cases:

k = 1 for a fabric made of fibers, such as carbon fibers,

k = 6 for a fiber mat, such as a continuous fiberglass mat.

[0032] With regard to the proportion V _f , it indicates the volume fraction of fibers (the volume fraction of the material forming the fibers in the total volume of the reinforcing material), i.e. has a value from 0 to 1 with the exception of 0, in other words, it indicates the percentage of fibers (by volume) in the reinforcing material (the edges/ends of which form a closed volume). The value of V _f is known as an intrinsic characteristic of the fibrous reinforcing material in question, and the value of V _f can be measured, for example, by measuring the areal density (g/m ² ), well known to the person skilled in the art, from which the volume fraction of V _f can be obtained fibers. Additionally, the international standard ISO 14127:2008 can be used to measure the volume fraction _Vf of fibers.

[0033] The term e _m represents the sum of the average thicknesses of fibrous reinforcing materials, expressed in meters (m); In other words, the average thickness of each fibrous reinforcing material is measured, and the value of the expression e _m is obtained by adding the average thicknesses for each of the fibrous reinforcing materials. The expression "average thickness" should be understood as the average value of the distances between two local extremes of the reinforcing material, that is, the distance between the two most distant points of the reinforcing material, located essentially opposite each other relative to the plane of extension of the fibrous reinforcing material, the measurement of the distance between the two points is repeated in a set areas of reinforcing material for the most accurate determination of the average thickness of the fibrous reinforcing material. In other words, the average thickness of the fibrous reinforcing material corresponds to the average value of the distances between a plurality of pairs of local extrema of said fibrous reinforcing material, spaced from each other in the thickness direction of said fibrous reinforcing material.

[0034] The term ΔP represents the hydraulic pressure gradient expressed in pascals (Pa), i.e. the pressure drop that occurs between the upper layer(s) of fibrous reinforcing material(s), which layer(s) are impregnated with a mixture of chemical components, and the lower layer(s) of fibrous reinforcing material(s), which is not yet impregnated with a mixture of chemical components, and , therefore, at a pressure substantially equal to atmospheric pressure. As can be seen from the third equation, the expression ΔP is a function of the surface density M _sd of the above mixture of chemical components, i.e. the amount of material formed by said mixture per unit area (in this case expressed in kg⋅m ^-2 ).

[0035] Thus, all terms and their respective meanings used to define the method of manufacture in accordance with the invention, in particular the impregnation time t _i , are essentially known data or can be determined/measured using technologies known to a person skilled in the art. the field of technology.

[0036] The term “creamy time” is to be understood as the time, starting from the moment of mixing the chemical components, necessary for the latter to enter into the polymerization reaction and the beginning of step c) of expansion and crosslinking of the mixture of components (= formation of fiber-reinforced polyurethane/polyisocyanurate foam) . The time of transition to a creamy mass is well known to a person skilled in the art. In other words, creamy time is the time before the mixture turns white due to bubble nucleation (gas storage cells) and foam expansion after mixing the chemicals at ambient temperature. Creamy time can be determined visually or using an ultrasonic transducer that detects a change in thickness indicative of foam formation.

[0037] By special selection of the characteristics of the fibrous reinforcing materials and the viscosity of the mixture of chemical components, it is possible to obtain a block of low density fiber reinforced polyurethane/polyisocyanurate foam having excellent fiber uniformity, in other words, the C _f content of the fibers is the same within a tolerance of ±35% or preferably ±20% in all parts of the foam block. This important characteristic makes it possible to obtain a fiber reinforced foam block that is light and easily adjustable in terms of dimensions and shapes, and also has excellent mechanical properties, as shown below in the tests carried out by the applicant.

[0038] Thus, the fiber-reinforced foam block obtained in accordance with the invention is characterized by a controlled and uniform structure and mechanical properties, in particular, fatigue strength, tensile strength in a plane perpendicular to expansion (measured in accordance with ISO 1926) , and a low in-plane thermal contraction coefficient (measured according to ASTM E 228), which is compatible with use in structural tanks, and preferably in type B or C tanks in accordance with ICG Rules (IMO) , i.e. as external insulation associated with self-supporting tanks for the storage and/or transport of very cold liquids, such as LNG or LPG.

[0039] Finally, the thermal properties of the fiber-reinforced foam block are at least identical to those of low-density non-fiber-reinforced foam blocks known in the art; more specifically, the foam block has a thermal conductivity of less than 30 mW/m⋅K (milliwatt per meter per kelvin) in the thickness direction E, i.e. 0.03 W/m⋅K, preferably less than 25 mW/m⋅K, more preferably less than 23 mW/m⋅K measured at 20°C.

[0040] The use of a chemical blowing agent in the composition of the invention can be combined with the use of a physical expanding agent. In this case, the physical expansion agent is preferably mixed in liquid or supercritical phase with the expandable (co)polymer composition and then converted to the gas phase in the expansion step of the polyurethane/polyisocyanurate foam.

[0041] Chemical and physical blowing agents are well known to the person skilled in the art, who chooses both in appropriate amounts depending on the polyurethane/polyisocyanurate foam that he wants to receive.

[0042] The term "polyols" should be understood as any carbon structure containing at least two OH groups.

[0043] Since the production of polyurethane, polyisocyanurate and polyurethane/polyisocyanurate foam depends on the ratio of isocyanate and polyol, polyurethane, polyisocyanurate or polyurethane/polyisocyanurate foam is obtained in accordance with this ratio. With the ratio between the polyol component and the isocyanate component:

from 1:1 to 1:1.3 get polyurethane PUR foam,

from 1:1.3 to 1:1.8 a polyurethane/polyisocyanurate PUR-PIC foam is obtained,

from 1:1.8 to 1:2.8 a polyisocyanurate PIC foam is obtained.

[0044] Polyisocyanates suitable for the manufacture of polyurethane, polyisocyanurate and polyurethane/polyisocyanurate foam are known to the person skilled in the art and include, for example, aromatic, aliphatic, cycloaliphatic and arylaliphatic polyisocyanates and mixtures thereof, with aromatic polyisocyanates being preferred.

[0045] Examples of polyisocyanates suitable within the scope of the present invention include aromatic isocyanates, e.g. isomers, toluene 2,4- and 2,6-diisocyanate (TDI), m- and p-phenylenediisocyanate, naphthalene 1,5-diisocyanate; aliphatic, cycloaliphatic or arylaliphatic isocyanates, e.g. DDI) and tetramethylxylylene diisocyanate (TMXDI). It is also possible to use any mixtures of these diisocyanates. Preferably, the polyisocyanates are the 4,4'-, 2,4'- and 2,2'-isomers of diphenylmethane diisocyanate (MDI).

[0046] In general, it is known practice to add during the manufacture of polyurethane, polyisocyanurate or polyurethane/polyisocyanurate foam to the mixture containing polyol, polyisocyanate and blowing agent, a reaction catalyst, which can be selected, for example, from tertiary amines, for example, N,N -dimethylcyclohexylamine or N,N-dimethylbenzylamine, or from organometallic compounds based on bismuth, potassium or tin.

[0047] Other preferred features of the invention are summarized below.

Preferably time t_i impregnation corresponds to the following expression for time t transition to a creamy mass of polyurethane / polyisocyanurate foam:

t + 0.1t_i < t_c < 2t_i.

In accordance with a preferred embodiment of the invention, expansion of the fiber-reinforced polyurethane/polyisocyanurate foam is physically constrained by the walls of a double-belt laminator (DBL) forming a tunnel of preferably rectangular cross-section with a side wall spacing of L and a horizontal wall spacing of E, which thus limits the expanding fiber-reinforced foam to obtain the aforementioned fiber-reinforced polyurethane/polyisocyanurate foam block.

[0048] Thus, in the embodiment using a two-belt laminator, thanks to the method in accordance with the invention, very significant savings are achieved, since the fiber-reinforced foam block is homogeneous and essentially has the necessary excellent mechanical properties, in particular along planes perpendicular to axis of thickness E, and along the same direction there is no need to subsequently cut the block to remove the end parts, which may be missing fibers and/or have egg-shaped cells not oriented along the axis E. Thus, the amount of material loss in the manufacturing method in accordance with the invention is from 0% to 10%, in general, less than 5%.

[0049] In accordance with a preferred embodiment of the invention, preferably the placement of the walls of the tunnel of the two-strip laminator is determined such that limiting the expansion of the fiber-reinforced polyurethane/polyisocyanurate foam results in a volume of fiber-reinforced polyurethane/polyisocyanurate foam at the outlet of the two-strip laminator, which is from 85% to 99 %, preferably from 90% to 99% of the expansion volume of the same fiber-reinforced polyurethane/polyisocyanurate foam in the case of free expansion without restriction from the walls of the two-belt laminator. In this case, a foam is obtained whose egg-shaped cells are preferably oriented along the E-axis, which provides the advantageous properties of resistance to collapse in the direction E (measured in accordance with ISO 844) along with the properties already described above with respect to the plane perpendicular to the E-axis. tests and experiments have been carried out to determine the broad and preferred ranges noted above, but they are not presented here for clarity and brevity.

[0050] Due to the above specific parameterization of limiting the expansion of fiber reinforced polyurethane/polyisocyanurate foam in a two-belt laminator, on the one hand, a low density fiber reinforced polyurethane/polyisocyanurate foam block is obtained, in which at least 60%, usually more than 80%, or even more than 90% of the cells storing a gas having a low thermal conductivity are extended in the longitudinal direction along an axis parallel to the axis of the thickness E of the foam block, which, in addition to the specific choice associated with the characteristics of the fibrous reinforcing materials and the viscosity of the mixture of chemical components, introduces contribute to the perfect uniformity of the fiber-reinforced foam block. These two characteristics (cell orientation and uniformity of _Cf fiber content in the block) make it possible to obtain a fiber reinforced foam block having excellent mechanical properties in the thickness direction E (compressive strength) and in the plane perpendicular to the thickness direction (tensile strength and low coefficient thermal contraction).

[0051] In accordance with another embodiment proposed by the invention, the expansion of fiber-reinforced polyurethane/polyisocyanurate foam is free, i. occurs without limitation due to the volume of the closed section.

[0052] In this case, in contrast to the embodiment of the method of manufacture according to the invention using a two-belt laminator, the manufacture of fiber-reinforced polyurethane/polyisocyanurate foam is considered "free expansion", since the expansion of fiber-reinforced foam is not limited on at least one side or on at least one expansion surface, so that the swelling of the fiber-reinforced foam on this side or on this surface is free, in contrast to the shape that determines the final volume. Typically, free expansion is accomplished by eliminating the (top) cap while the sidewalls prevent the foam from spreading to the sides and the foam naturally swells upwards, possibly beyond the top ends of the sidewalls.

[0053] Preferably, after the free expansion step of the fiber-reinforced polyurethane/polyisocyanurate foam, said fiber-reinforced foam is cut to obtain the above fiber-reinforced polyurethane/polyisocyanurate foam block.

[0054] In accordance with one of the possibilities proposed by the invention, which is not shown in the attached drawings, immediately after the stage of impregnation of fibrous reinforcing materials, a pressure application system (which may be , for example, a system of rolls of the type known as pressure roll) designed to apply pressure to the upper surface of the mass formed by said mixture and fibers. The pressure application system, on the one hand, makes it possible to even out the upper surface of the mass and, due to the pressure acting on the mass, contributes to the acceleration of the impregnation of the fibers with the aforementioned mixture. The pressure application system may consist of one or two rolls whose relative positions above the slurry and possibly under the foam support are adjusted so that the slurry is perfectly evenly distributed. Thus, at any point in the area formed by the space between two rolls or between the upper roll and the conveyor belt, an equivalent amount of liquid mass is provided. In other words, the main task of the pressure application system is to complement the liquid distributor in the sense that it contributes to uniform distribution of the liquid mass in the thickness/width direction before the main expansion.

[0055] Preferably, the dynamic viscosity η of the above mixture of components is from 30 MPa⋅s to 3000 MPa⋅s (or from 0.03 Pa⋅s to 3 Pa⋅s), preferably from 50 MPa⋅s to 1500 MPa⋅s (or 0.05 Pa⋅m to 1.5 Pa⋅s), under standard temperature and pressure conditions (STPC) corresponding to a temperature of 25°C and a pressure of 1015°MPa.

[0056] The dynamic viscosity of a mixture of components can be determined using a viscometer, for example, a Brookfield viscometer (Brookfield), or a rheometer, for example, using the ISO 2555 standard.

[0057] Preferably, at least 60% of the above gas storage cells, preferably having a low thermal conductivity, are shaped elongated or elongated along an axis parallel to the thickness axis E of the fiber-reinforced polyurethane/polyisocyanurate foam block;

[0058] Even more preferably, at least 80%, preferably at least 90% of the aforementioned gas storage cells, preferably having a low thermal conductivity, are shaped elongated or elongated along an axis parallel to the thickness E axis of the fiber reinforced block polyurethane/polyisocyanurate foam.

[0059] An elongated or elongated shape can be defined as a shape that is elongated, that is, it has one dimension (length) that exceeds other dimensions (width and thickness).

[0060] In this case, it is understood that the characteristic associated with the elongated shape of the cells storing a gas, preferably having a low thermal conductivity, and their content/proportions in a block in accordance with the invention, is considered in the context of implementing a manufacturing method using a two-belt laminator, but it absolutely not limited to this scenario. This is because in the case of free expansion, in particular in the absence of a top wall/cover to limit the expansion of the fibre-reinforced foam, a preferable orientation of the gas storage cells, preferably having a low thermal conductivity, is also provided.

[0061] In accordance with one embodiment of the invention, the long to continuous fibers consist of glass fibre, carbon fiber, or any other organic or inorganic material, preferably glass fibers, usually polymeric, metallic, ceramic, glassy, inorganic or organic nature, for example, natural fibers , for example, hemp or flax fiber, with glass fiber being preferred.

[0062] Preferably, fibrous reinforcing materials are placed across the entire width L, and step b) impregnating the fibers with a mixture of components to obtain a fiber-reinforced polyurethane/polyisocyanurate foam and blowing agent is carried out using a controlled liquid distributor simultaneously over the entire width L.

[0063] By the term "simultaneously" it is to be understood that the liquid mixture (of the reactants and at least the blowing agent) reaches the fibers in the section of width L simultaneously throughout this section, so that the impregnation of the different fibrous reinforcing materials begins or proceeds in the direction of thickness ( or height) of a foam block in the same section of width at the same time or at the same speed.

[0064] Preferably, the blowing agent consists of a physical and/or chemical expanding agent, preferably a combination of the two types.

[0065] Preferably, the physical expanding agent is selected from alkanes and cycloalkanes having at least 4 carbon atoms, dialkyl ethers, esters, ketones, acetals, fluoroalkanes, pterolefins having from 1 to 8 carbon atoms, and tetraalkylsilanes having from 1 up to 3 carbon atoms in the alkyl chain, in particular tetramethylsilane, or mixtures thereof.

[0066] Under this assumption, propane, n-butane, isobutane, cyclobutane, n-pentane, isopentane, cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether, methyl butyl ether, methyl formate, acetone can be mentioned as examples of compounds. and fluoroalkanes; moreover, fluoroalkanes are selected from fluoroalkanes that do not destroy the ozone layer, for example, trifluoropropane, 1,1,1,2-tetrafluoroethane, difluoroethane and heptafluoropropane. Examples of pterolefins include 1-chloro-3,3,3-trifluoropropene or 1,1,1,4,4,4-hexafluorobutene (eg HFO FEA1100 sold by DuPont).

[0067] In accordance with a preferred embodiment of the invention, the selected physical expanding agent is 1,1,1,3,3-pentafluoropropane or HFC-245fa (sold by Honeywell), 1,1,1,3,3-pentafluorobutane or 365mfc (e.g. Solkane® 365mfc sold by Solvay), 2,3,3,3-tetrafluoropropene-1, 1,1,1,2,3,3,3-heptafluoropropane (also known worldwide as HFC-227ea, e.g. sold by DuPont), 1,1,1,4,4,4-hexafluorobutene (e.g. HFO FEA1100 sold by DuPont), trans-1-chloro-3,3,3-trifluoropropene (Solstice LBA, Honeywell) or their mixture.

[0068] Preferably, the chemical expansion agent consists of water.

[0069] Preferably in step a) of mixing the chemical components, the nucleating gas is introduced into at least one polyol compound, preferably using a static/dynamic mixer at a pressure of 20 to 250 bar, the nucleating gas is from 0% to 50% by volume of the polyol, preferably from 0.05% to 20% by volume of the polyol.

[0070] Preferably, in step a) mixing the chemical components, the temperature of each of the polyurethane/polyisocyanurate reactants is 10°C to 40°C, preferably 15°C to 30°C.

[0071] Preferably, in accordance with the preferred embodiment of the invention, the final mixing of the streams of polyols, isocyanate and/or blowing agent occurs in the mixing head at low pressure (<20 bar) or high pressure (>50 bar) using a dynamic or static mixer.

[0072] In accordance with one of the possibilities proposed by the invention, in step a) an organophosphorus flame retardant is additionally added to the mixture, preferably triethyl phosphate (TEP), tris (2-chloroisopropyl) phosphate (TCPP), tris (1,3-dichloroisopropyl) phosphate (TDCP), tris(2-chloroethyl) phosphate or tris(2,3-dibromopropyl) phosphate or a mixture thereof, or an inorganic flame retardant, preferably red phosphorus, expandable graphite, alumina hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate, derivatives calcium sulfate or cyanuric acid, or a mixture thereof.

[0073] The use of diethyl ethane phosphonate (DEEP), triethyl phosphate (TEP), dimethyl propyl phosphonate (DMPP), or diphenylcresyl phosphate (DPC) as a fire retardant may also be contemplated.

[0074] If a fire retardant is present in the composition according to the invention, its amount is from 0.01% to 25% by weight of the polyurethane/polyisocyanurate foam.

[0075] Preferably, the content of C _f fibers is from 7% to 15% by weight of the block of fiber reinforced foam. Preferably, the C _f content of the fibers is not more than 30% by weight of the fiber reinforced foam block.

[0076] The invention also relates to a fiber-reinforced polyurethane/polyisocyanurate foam block for a thermal insulation board of a sealed and thermally insulated tank, directly obtained in accordance with the method briefly described above, and the fiber-reinforced polyurethane/polyisocyanurate foam block consists of gas storage cells, preferably having low thermal conductivity and having a density of less than 50 kg⋅m ^-3 with a C _f fiber content of at least 4% by weight of the fiber reinforced foam block.

[0077] The foam block is characterized in that the fibers are evenly distributed in the fiber-reinforced polyurethane/polyisocyanurate foam block, so that the _Cf content varies by only ±35% in all regions or areas of said fiber-reinforced polyurethane/polyisocyanurate foam block, or preferably in even more limited range, i.e. about ±20%.

[0078] Thus, as an example, if the content of C _f fibers in the block is 4%, that is, the average in the block, this means that the fiber content may vary depending on the area of the block in the range from 2.8% to 5 .2% (and preferably from 3.2% to 4.8%), and if the average content of C _f fibers is 15%, then the fiber content may vary depending on the block area in the range from 10.5% to 19.5 % (and preferably from 12% to 18%).

[0079] Such a block of foam essentially has characteristics different from those of a block made in accordance with prior art manufacturing techniques. It may be noted that the characteristics relating to the nature or amount of the various elements presented above in relation to the method for manufacturing the fiber reinforced foam block can, if necessary, more accurately define the fiber reinforced polyurethane/polyisocyanurate foam block according to the invention.

[0080] Preferably, the density of said foam block is 20 to 50 kg/m ³ , preferably 30 to 45 kg/m ³ .

[0081] The invention also relates to a sealed and heat-insulating tank built into a supporting structure, said tank consisting of:

[0082] a tank built into a supporting structure, containing a sealed and heat-insulating tank containing at least one sealed metal membrane, consisting of a plurality of metal strips or metal plates that may contain corrugations, and a heat-insulating plate containing at least one heat-insulating barrier adjacent to said membrane, or

[0083] a type B or C tank as defined in the UGC Code, containing at least one thermal insulation board.

[0084] The reservoir according to the invention is characterized in that the thermal insulation board comprises a fiber reinforced polyurethane/polyisocyanurate foam block, briefly described above.

[0085] The term "UGC Code" (IGC Code) should be understood as "International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk", well known to a person skilled in the art in the art, which describes tanks types B and C.

[0086] It should be noted that, in particular, in accordance with the UGC Code (IGC Code), you can use the expression "membrane tank" instead of the expression "built-in tank" to refer to tanks of the same category, in particular, installed on tankers carrying and / or storing at least partially liquefied gas. "Membrane tanks" are built into a supporting structure, while Type B or C tanks are considered self-supporting.

[0087] The reservoir contains a plurality of blocks of fiber-reinforced polyurethane/polyisocyanurate foam directly obtained in accordance with the above manufacturing method.

[0088] Finally, the invention also relates to a vessel for transporting a cold liquid product, the vessel comprising at least one hull and a sealed and heat-insulating reservoir, as briefly described above, located in the hull.

[0089] Preferably, in the case where the tank consists of a tank built into a supporting structure (membrane tank), the vessel contains at least one sealed and insulating tank, as described above, and said tank contains two consecutive sealing barriers, while one, the main one is in contact with the product contained in the tank, and the other, auxiliary, is located between the main barrier and the supporting structure, preferably formed by at least part of the walls of the vessel, with two sealing barriers alternating with two heat-insulating barriers or one heat-insulating barrier located between the main barrier and supporting structure.

[0090] Such tanks are commonly referred to as built-in tanks in accordance with the Code of the International Maritime Organization (IMO) (International Maritime Organization Code), for example, NO type tanks, including types NO 96®, NO 96L03®, NO 96L03+® or NO 96 Max®, or Mark III®, with NO tanks being preferred.

[0091] Preferably, a membrane type or type B or C tank contains liquefied natural gas (LNG) or liquefied natural gas (LNG).

BRIEF DESCRIPTION OF THE DRAWINGS

[0092] The following description is given by way of example only, and not limitation, with reference to the accompanying drawings, in which:

[0093] FIG. 1 is a schematic view illustrating the various steps of the manufacturing method according to the invention.

[0094] FIG. 2 is a schematic representation of an embodiment of a controllable liquid distributor in accordance with the invention.

[0095] FIG. 3 is a schematic view of two groups of thermal insulation panels fastened to each other, respectively forming a main insulating space and a secondary insulating space for a tank, the panels being formed by a plurality of fiber reinforced polyurethane/polyisocyanurate foam blocks in accordance with the invention;

[0096] FIG. 4 is a schematic cutaway view of an LNG tanker tank in which the two groups of thermal insulation panels shown in FIG. 3, and a terminal for loading/unloading this tank.

DESCRIPTION OF EMBODIMENTS

[0097] Preferably, the manufacture of the fiber-reinforced polyurethane/polyisocyanurate according to the invention is carried out in the presence of catalysts to accelerate the reaction of the isocyanate and the polyol. Such compounds are described, for example, in the prior art document entitled "Kunststoffhandbuch, Volume 7, Polyurethane" published by Carl Hanser, 3rd edition, 1993, chapter 3.4.1. These compounds contain amine-based catalysts and organic-based catalysts.

[0098] Preferably, the manufacture of the fiber-reinforced polyurethane/polyisocyanurate of the invention is carried out in the presence of one or more stabilizers designed to promote the formation of regular honeycomb structures during foam formation. These compounds are well known to the person skilled in the art, and by way of example foam stabilizers containing silicones, for example siloxane-oxyalkylene copolymers and other organopolysiloxanes, may be mentioned.

[0099] A person skilled in the art knows the amount of stabilizers, ranging from 0.5% to 4% by weight of polyurethane/polyisocyanurate foam, which should be used depending on the intended reagents.

[0100] In accordance with one of the possibilities offered by the invention, in step a) the mixture of chemical components may include plasticizers, for example, polybasic esters, preferably dibasic esters of carboxylic acids with monohydric alcohols, or may consist of polymeric plasticizers, for example , polyesters of adipic, sebacic and/or phthalic acids. The person skilled in the art will know how much plasticizers are provided, typically from 0.05% to 7.5% by weight of the polyurethane/polyisocyanurate foam, depending on the reagents used.

[0101] Organic and/or mineral fillers, in particular reinforcing fillers, for example, silicon-containing minerals, metal oxides (for example, kaolin, titanium or iron oxides) and/or metal salts, can also be provided in the mixture of chemical components. The amount of these fillers, if present in the mixture, is typically between 0.5% and 15% by weight of the polyurethane/polyisocyanurate foam.

[0102] It should be noted that the present invention does not provide for the addition of technical knowledge in the field of manufacturing polyurethane/polyisocyanurate foam, both in relation to the nature of the main chemical components and possible functional agents, and in relation to their respective amounts. The person skilled in the art is aware of how different types of fiber reinforced polyurethane/polyisocyanurate foam can be made, and the present method of manufacture relates to the specific selection of the permeability characteristics of the fibrous reinforcing materials, as well as the specific selection of the viscosity of the foam during impregnation of said reinforcing materials, taking into account relatively high or high fiber content from long to continuous, so that the impregnation time t _i is less or slightly less than the creaming time t _c of the polymeric foam in question.

[0103] Thus, the present invention, as set forth herein, is not primarily directed to a new method for chemically manufacturing fiber reinforced polyurethane/polyisocyanurate foam, but to a new method for manufacturing a fiber reinforced polyurethane/polyisocyanurate foam block, in which specific characteristics the permeability of the fibrous reinforcing materials and the viscosity/creaming time of the polyurethane/polyisocyanurate foam are determined to follow the rule t _i < t _c and preferably:

[0104] [Math expression 1]

[0105] or in other words t _i + 0.1t _i < t _c < 2t _i , and the impregnation of the fibers with foam is carried out by pouring.

[0106] Thus, as seen in FIG. 1, a plurality of fibrous reinforcing materials 10 are unwound and laid in parallel alignment with each other on a conveyor belt 11 for transporting the reinforcing materials 10 and polyurethane/polyisocyanurate foam forming components. In fact, the impregnation of the fibrous reinforcing materials 10 in the context of the present invention is carried out by gravity, i.e. a mixture of 12 chemical components, blowing agent (s) and possible other functional agents used to obtain a polyurethane/polyisocyanurate foam, is poured from a liquid distributor located above fibrous reinforcing materials 10, directly on the fibrous reinforcing materials 10.

[0107] Thus, the aforementioned mixture 12 must uniformly impregnate all fibrous reinforcing materials 10, whether one or more mats or one or more fabrics, during the creaming time t _c , so that the beginning of the expansion of the polyurethane/polyisocyanurate foam occurs after or at the earliest when all fibrous reinforcing materials 10 are completely impregnated with mixture 12. In this case, due to the characteristics of fibrous reinforcing materials and polyurethane/polyisocyanurate foam, which are determined in accordance with the invention, the expansion of polyurethane/polyisocyanurate foam is carried out while maintaining excellent fiber uniformity 10 per block of polyurethane/polyisocyanurate foam.

[0108] In the context of the present invention, the time of transition to a creamy mass of the components of the mixture 12 for the formation of polyurethane/polyisocyanurate foam is known to a person skilled in the art and is chosen so that the conveyor belt 11 delivers a mass formed from a mixture of 12 components, blowing agent and fibers 10, for example, in a two belt laminator, which is not shown in the attached drawings, at the very beginning of the foam expansion, in other words, the expansion of the polyurethane/polyisocyanurate foam is completed in the two belt laminator.

[0109] In such an embodiment, with the dual belt laminator (DBL) before the dual belt laminator, i. e. between the zone of impregnation of the fibers with the mixture and the two-belt laminator, an optional pressure application system using one or two rolls is located. In the case of using a two belt laminator, the expansion of the foam volume occurs in the two belt laminator when the expansion volume of this foam reaches from 30% to 60% of the expansion volume of the same foam under free expansion, i.e. without any restrictions. However, the dual belt laminator may limit the expansion of the polyurethane/polyisocyanurate foam in the second phase of expansion when it is close or relatively close to its maximum expansion, i.e. when the expansion causes the foam to be close to all the walls forming the rectangular or square tunnel of the double belt. laminator. According to another way of providing a particular choice of manufacturing method in accordance with the invention, the gel point of the mixture of components, i. the moment at which at least 60% polymerization of the mixture of components is achieved, in other words, from 70% to 80% of the maximum expansion volume of the mixture, necessarily occurs in a two-belt laminator, possibly at the second half of the length of a two-belt laminator (i.e. closer to the exit from the laminator than to the laminator inlet).

[0110] With regard to the function of simultaneously distributing the mixture of chemical components 12 and blowing agent across the entire width L of the fibrous reinforcing materials 10, it is provided by the controlled liquid distributor 15 shown in FIG. 2. The distributor 15 includes a channel 16 for supplying a mass formed from a mixture of 12 chemical components and at least a blowing agent from a tank forming a reagent mixer, which is not shown in the attached drawings, in which, on the one hand, all chemical components and blowing agent are mixed agent, and, on the other hand, in particular, nucleation and even heating of such a mixture is performed. Then the liquid mass formed from the mixture 12 of chemical components and blowing agent, is divided under pressure into two channels 17, extended transversely relative to the respective end of two identical distribution plates 18, continuing along the width L (each of which has a length essentially equal to L/2 ) containing a plurality of nozzles 19 for supplying the flow of said mixture 12 to the fibrous reinforcing materials 10. The flow nozzles 19 consist of channels of a calibrated cross section having a given length. Thus, the length of the flow nozzles 19 is determined so that the liquid exits at the same rate for all nozzles 19 for the simultaneous impregnation of the fibrous reinforcing materials 10 in the section of the width L of the fibrous reinforcing materials 10, and so that the surface density of the liquid supplied at right angles from each injectors were the same. At the same time, if we consider the section of the width L of the fibers 10, the latter are impregnated simultaneously, so that the impregnation of the layers of fibers 10 with mixture 12 is carried out at all points of this section in an identical way, which contributes to obtaining a perfectly homogeneous block of fiber-reinforced foam at the outlet of the two-belt laminator.

[0111] The controllable liquid distributor 15 shown in FIG. 2 is an exemplary embodiment in which two identical distribution plates 18 are used, but other designs can be provided as long as the function of simultaneously distributing liquid over the width section of the fibers 10 is provided. Of course, the main technical characteristic used in this document is in different lengths of the flow nozzles 19, which is greater or less depending on the route or path of the liquid mixture 12 from the supply channel 16 of the distributor 15 to the flow nozzle 19 in question.

[0112] One of the aspects important to achieve proper impregnation of the fibrous reinforcing materials 10 just before the time t _c of the transition to a creamy mass of polyurethane / polyisocyanurate foam is the choice of specific viscosity of the liquid (consisting of a mixture of 12 chemical components and a blowing agent) depending on the specific characteristics of fibrous reinforcing materials. The selected viscosity range, as well as the permeability characteristics of the fibrous reinforcing materials, must ensure proper liquid penetration into the first layers of fibers 10 in order to reach subsequent layers up to the last layer (the bottom layer of fibers 10, i.e. the layer located at the very bottom in a pack of fibrous reinforcing materials ), so that the impregnation time t _i of the fibers 10 is within the time period determined by the chemical components substantially corresponding to the creaming time t _c (but always less than it). The viscosity of the mixture of 12 components is chosen, for example, by heating, adding plasticizers and/or more or less pronounced nucleation so that the impregnation of all fibers 10 with a mixture of 12 chemical components and a blowing agent over a section of width L is achieved just before the time of transition to a creamy mass, that is before or just before the start of expansion of the polyurethane/polyisocyanurate foam.

[0113] The fiber-reinforced foam block is intended for use in a very specific environment and therefore must provide certain mechanical and thermal properties. The fiber-reinforced foam block produced by the manufacturing method of the present invention is typically part of the thermal insulation board 30, i.e. in the example used in FIG. 3 forms a top or main panel 31 and/or a bottom or sub-panel 32 of such an insulating plate 30 of a tank 71 intended to receive a very cold liquid such as LNG or LPG. Such a tank 71 may be installed, for example, in a surface tank, on a floating barge, or the like. (e.g. FSRU "Floating Gas Regasification and Storage Unit" or FLNG "Floating Liquefied Natural Gas Unit") or on a vessel, such as an LNG tanker, transporting energy liquid between two ports.

[0114] With reference to FIG. 4 is a sectional view of an LNG tanker 70 illustrating a sealed and insulating tank 71 in a generally prismatic shape mounted in a double hull 72 of the vessel. The tank wall 71 comprises a main pressurized barrier for contact with the LNG contained in the tank, an auxiliary pressurized barrier located between the main pressurized barrier and the double hull 72 of the ship, and two insulating barriers located respectively between the main pressurized barrier and the auxiliary pressurized barrier and between auxiliary pressurized barrier and double housing 72.

[0115] As is known, the loading / unloading pipelines 73 located on the upper deck of the vessel can be connected using appropriate connectors to a sea or port terminal for supplying LNG from the tank 71 or to it.

[0116] FIG. 4 illustrates an example of an offshore terminal comprising a loading and unloading station 75, a subsea pipeline 76, and an onshore facility 77. The loading and unloading station 75 is a fixed offshore facility comprising a movable boom 74 and a tower 78 that supports the movable boom 74. The movable boom 74 supports the tether. insulated hoses 79, which can be connected to the pipelines 73 loading/unloading. The 74 swivel mobile boom adapts to LNG tankers of all sizes. Inside the tower 78 is a connecting pipeline, which is not shown. The loading and unloading station 75 allows the loading and unloading of the LNG tanker 70 from or to the surface facility 77. This structure contains tanks 80 for storing liquefied gas and connecting pipelines 81 connected by an underwater pipeline 76 to the station 75 loading or unloading. The subsea pipeline 76 allows LNG to be transferred between the loading or unloading station 75 and the surface facility 77 over a long distance, such as 5 km, which allows the LNG tanker 70 to be stopped far offshore during loading and unloading operations.

[0117] To create the pressure necessary for the transfer of liquefied gas, pumps installed on the ship 70 and/or pumps installed in the surface structure 77 and/or pumps installed at the loading and unloading station 75 are used.

[0118] As stated above, the use or application of the object of the present invention, namely in this case a block of fiber reinforced polyurethane / polyisocyanurate foam, is not intended to be limited to a tank built into a supporting structure, and it is also provided for tanks of type B and C according to IGC Code in effect as of the filing date of this patent application, and for future versions of this Code, unless significant modifications are made to Types B and C tanks, in addition, it must be understood that in the case Modifications of the IGC Code (IGC Code) fiber-reinforced polyurethane/polyisocyanurate foam block in accordance with the present invention can be applied to other types of tanks.

[0119] The following are some of the experiments and tests conducted by the Applicant to evaluate the subject matter and scope of the invention, while it is assumed that other tests/experiments were carried out, which, if necessary, can be provided later.

[0120] To demonstrate the invention, a polyurethane foam composition is used, including fibers in the form of mats, and the fibers are always fibers from long to continuous; more specifically, the lengths of these fibers in the composition according to the invention and in the composition according to the prior art are exactly the same. The Applicant in particular tested the subject matter of the invention using fibers presented as a fabric and the results obtained were equivalent or substantially similar to those obtained using a mat of fibers as presented below.

[0121] For each polyurethane foam, the fibrous reinforcing materials have characteristics that are defined as corresponding to the present invention (shown in bold in the results table below), or characteristics that do not meet the definition of the invention; more precisely, in the latter case, the time t _i of impregnation of the fibers exceeds the time t _c of the transition into a creamy mass of polyurethane foam. It should be noted here that the case when the time t _{i of} the impregnation of the fibers is much less than the time t _c of the transition to a creamy mass, in other words, the time t _c of the transition to a creamy mass is more than twice the time t _{i of} impregnation of the fibers (t _c > 2t _i ), excluded, since in this case the method of manufacture obviously has no real industrial feasibility.

[0122] Thus, it is envisaged that only the combination of the specific impermeability characteristics of the fibrous reinforcing materials with the choice of a polyurethane foam having a specific creamy time or a polyurethane foam selected for the characteristics of said fibrous reinforcing materials, but no other parameters for manufacturing a block of polyurethane foam, modified and different for different manufacturing methods in accordance with the invention and in accordance with the prior art. As non-limiting examples, the fact that nucleation, the amount of blowing agents, the reaction temperatures, the nature and amount of the mixture of chemical components, the pouring process, the distance between the pouring point of the mixture of chemical components and the two-belt laminator or device allowing free expansion, if necessary, are strictly identical in the cases according to the invention and in the cases according to the prior art.

[0123] In this example, polyisocyanurate foam was chosen to illustrate the invention for clarity and brevity, but equivalent or substantially similar results were obtained using polyurethane foam as well as polyurethane/polyisocyanurate blends.

[0124] Similarly, in the manufacture of fiber reinforced foam, the results of which are given below, the free expansion technology was used, but the Applicant has demonstrated that equivalent or practically similar results in relation to fiber reinforced foam in accordance with the invention and fiber reinforced foam in accordance with the state of the art techniques were obtained using a two-belt laminator.

[0125] In addition, it should be understood that all compositions tested in the following are considered under identical density conditions, it being understood that the density parameter is involved in evaluating performance in terms of compressive strength.

[0126] For a composition according to the prior art, the permeability characteristics of the fibrous reinforcing materials and the creaming time t _c of the polyisocyanurate foam are as follows:

[0127] [Table 1]

type of product Content
(relative proportion of different components) Description Commercial link to the product Polyol 1 60-70 190-230 mg KOH/g aromatic polyester polyols Polyol 2 15-25 295-335 mg KOH/g aromatic polyester polyols flame retardant 10-20 triethyl phosphate Isocyanate 240-290 30-31.5% NCO polymeric methylene diphenyl diisocyanate type Voracor CM 388 Water (chemical blowing agent) 0.5-0.7 Physical Blowing Agent 20-24 Mixture of pentane isomers: cyclo- and isopentane Silicone surfactant 0.5-1.5 PEO/PPO grafted silicone Catalysts 1-1.6 Voracor CM639 0.4-0.7 Voracor CM420 Additives 1-2 Voratherm CN821

K _c \u003d 5.2 × 10 ^-9 m ² ,

where r _f = 16 µm; p = 0.978; k = 6; τ = 2; V _f = 0.022,

t _i (impregnation time) = 41 s (seconds).

where η = 0.45 Pa⋅s; _em = 2.4 mm; ΔP = 5140 Pa; M _sd \u003d 4.2 kg / m ² ,

t _c (transition time to a creamy mass) = 15 s.

[0128] For compositions in accordance with the invention, the permeability characteristics of fibrous reinforcing materials and the time t _c creamy mass of polyisocyanurate foam are as follows:

[0129] [Table 2]

type of product Content
(relative proportion of different components) Description Commercial link to the product Polyol 1 60-70 190-230 mg KOH/g aromatic polyester polyol Polyol 2 15-25 295-335 mg KOH/g aromatic polyester polyol flame retardant 10-20 triethyl phosphate Isocyanate 240-290 30-31.5% NCO polymeric methylene diphenyl diisocyanate type Voracor CM 388 Water (chemical blowing agent) 0.5-0.7 Physical Blowing Agent 20-24 Mixture of pentane isomers: cyclo- and isopentane Silicone surfactant 0.5-1.5 PEO/PPO grafted silicone Catalysts 1-1.6 Voracor CM639 0.4-0.7 Voracor CM420 Additives 1-2 Voratherm CN821

K _c \u003d 3 × 10 ^-8 m ²

where r _f = 106 µm; p=0.94; k = 6; τ = 2; V _f = 0.057,

_ti = 11 s,

where η = 0.45 Pa⋅s; _em = 3 mm; ΔP = 4116 Pa; M _sd \u003d 4.2 kg / m ² ,

t _c = 15 s.

[0130] It should be noted that the creaming time t _c for the polyisocyanurate foam used is logically the same, since the foam used is identical in any case, both in accordance with the prior art and in accordance with the invention.

[0131] Some test results are given below in a simplified form to illustrate Applicant's conclusions when the fibrous reinforcing materials are in the form of at least one fiberglass mat.

[0132] [Table 3]

Mixture of chemical components and blowing agents (identical density
< 50 kg⋅m ^-3 tested compositions with fibers) Characterization of the distribution of fibers in the foam
(in the central part according to the height/thickness of the block) Voltage characteristic according to standard
ISO 1926
(stress in the plane of the mat(s)) Thermal contraction coefficient according to ASTM E 228 Approximately 4% by weight fiberglass
(prior art) 3.6±0.6 (standard deviation), i.e. ±18 (% standard deviation) where Et: Young's modulus and Rt: elastic limit 37±5×10 ^-6 K ^-1 Approximately 8% by weight fiberglass
(prior art) 8.9±9 (standard deviation), i.e. ±102% (% standard deviation) Not measurable
High material heterogeneity: separation of fibers and foam, poor impregnation and no distribution of fibers Not measurable Approximately 8% by weight fiberglass 8.7±2 (standard deviation), i.e. ±26% (% standard deviation) 27±6×10 ^-6 K ^-1 Approximately 14% by weight fiberglass 13.8±3.6 (standard deviation), i.e. ±31% (% standard deviation) 25±6×10 ^-6 K ^-1

[0133] As can be seen from the results presented in the table above, according to the three criteria considered for comparing the obtained fiber-reinforced foam, the foam obtained in accordance with the invention shows results that are significantly superior to the results of fiber-reinforced foam obtained in accordance with the known state of the art. technology.

[0134] In addition, it should be noted that the fiber-reinforced polyurethane/polyisocyanurate foam obtained in accordance with the invention does not show any significant deterioration in properties in terms of (very low) thermal conductivity. Thus, by way of example, for a fibre-reinforced foam having a fiber content of 10% by weight according to the invention, the following thermal conductivity values are obtained:

[0135] [Table 4]

Thermal conductivity (mW/m K) at -160°C at -120°C at +20°C 10-14 11-16 23-27

[0136] Although the invention has been described with reference to several specific embodiments, it is obvious that it is not limited to them in any way, and that it contains all technical equivalents of the described means, as well as combinations thereof, if they are within the scope of the invention.

[0137] The use of the verb "comprise" or "include" and derivative forms does not exclude the presence of other elements or other steps other than those mentioned in the claim.

[0138] In the claims, any reference position in parentheses should not be interpreted as limiting the claim.

Claims (44)

1. A method of manufacturing a fiber reinforced polyurethane/polyisocyanurate foam block for a thermal insulation board of a sealed and thermally insulated tank consisting of gas storage cells and has a density of less than 50 kg⋅m ^-3 with a C _f content of fibers of at least 4% by weight. mass of the block of fiber reinforced foam, and the manufacturing method includes the following steps: a) a step in which (12) the chemical components necessary for the production of polyurethane/polyisocyanurate foam are mixed, said components containing reagents for the production of polyurethane/polyisocyanurate, additionally at least one reaction catalyst, additionally at least one emulsifier and at least one blowing agent, b) a step in which, under the action of the gravitational flow of the aforementioned mixture (12), chemical components are impregnated with a plurality of fibrous reinforcing materials (10) selected from fiber fabrics and fiber mats, said fibers having a length of at least five centimeters (cm) and arranged in superimposed layers, in which the fibrous reinforcing materials (10) are extended essentially in the direction perpendicular to the direction of said gravitational flow, and the fibrous reinforcing materials (10) have a permeability K _c with respect to the aforementioned mixture (12) of chemical components, expressed in m ² , equal to K _c = (r _f ² × p ³ )/(k × τ ² × 4 × V _f ² ), where r _f is the radius of the fibers, expressed in meters (m), p - fiber porosity (10), has a value from 0 to 1, k - form factor depending on the nature of the fibrous reinforcing material (10), where k = 1 for a fabric of fibers, k = 6 for a mat of fibers, τ - crimp, depending on the location of the fibers, V _f - volume fraction of fibers, having a value from 0 to 1 with the exception of 0, c) a step in which the fiber-reinforced polyurethane/polyisocyanurate foam is formed and expanded, characterized in that the above mixture (12) of chemical components has a dynamic viscosity η in stage b) impregnation, so that the time t _i impregnation of the fibers is less than the time t _c of the transition to a creamy mass of polyurethane / polyisocyanurate foam, and the time t _i impregnation of the fibers is : t _i = (η × _em ² )/(K _c × ∆P), ΔP = (M _sd × g _T × k _p ), where η is the dynamic viscosity expressed in pascal⋅seconds (Pa⋅s), e _m is the sum of the average thicknesses of the fibrous reinforcing materials (10), expressed in meters (m), with each fibrous reinforcing material having an average thickness corresponding to the average value of the distances between a plurality of pairs of local extrema of said fibrous reinforcing material (10) spaced apart from each other in the thickness direction of said fibrous reinforcing material, ΔP is the pressure gradient, expressed in pascals per meter (Pa/m), M _sd - surface density of the above mixture (12) of chemical components, expressed as mass per unit area (kg⋅m ^-2 ), g _T - the force of the earth's gravity, in this case it is considered equal to 9.8 N⋅kg ^-1 , k _p - average pressure coefficient, constant equal to 0.5. 2. The method according to claim 1, wherein the impregnation time t _i corresponds to the following formula with respect to the creaming time t _c of the polyurethane/polyisocyanurate foam:

. 3. The method according to claim 1 or 2, wherein the expansion of the fiber-reinforced polyurethane/polyisocyanurate foam is physically limited by the walls of the two-belt laminator, forming a tunnel of preferably rectangular cross-section with a distance between the walls located on the sides equal to L, and the distance between the walls located horizontally , equal to E, which thus limits the expanding fiber-reinforced foam to produce the aforementioned fiber-reinforced polyurethane/polyisocyanurate foam block. 4. The method of claim 3, wherein the placement of the tunnel walls of the dual belt laminator is determined such that limiting expansion of the fiber reinforced polyurethane/polyisocyanurate foam results in a volume of fiber reinforced polyurethane/polyisocyanurate foam exiting the dual belt laminator of 85 to 99%, preferably 90 to 99% expansion volume of the same fiber-reinforced polyurethane/polyisocyanurate foam in the case of free expansion without being restricted by the walls of the dual belt laminator. 5. The method according to claim 1 or 2, wherein the expansion of the fiber-reinforced polyurethane/polyisocyanurate foam is free, i. occurs without limitation due to the volume of the closed section. 6. The method of claim 5, wherein, after the free expansion step of the fiber reinforced polyurethane/polyisocyanurate foam, said fiber reinforced foam is cut to form the above fiber reinforced polyurethane/polyisocyanurate foam block. 7. The method according to claim 1 or 2, wherein the dynamic viscosity η of the above mixture (12) of the components is from 30 to 3000 MPa⋅s, preferably from 50 to 1500 MPa⋅s under standard conditions of temperature and pressure. 8. The method according to claim 1 or 2, wherein at least 60% of the above gas storage cells, preferably having a low thermal conductivity, are shaped elongated or elongated along an axis parallel to the thickness E axis of the fiber reinforced polyurethane/polyisocyanurate foam block. 9. The method according to claim 1 or 2, in which at least 80%, preferably at least 90% of the above-mentioned gas storage cells, preferably having a low thermal conductivity, are shaped elongated or elongated along an axis parallel to the axis of the thickness E of the reinforced block polyurethane/polyisocyanurate foam fiber. 10. The method according to claim 1 or 2, wherein the long to continuous fibers consist of glass fibers, carbon fibers or any other organic or inorganic material, preferably glass fibers. 11. The method according to claim 1 or 2, wherein the fibrous reinforcing materials (10) are placed over the entire width L, and step b) of impregnating the fibers with a mixture (12) of components to obtain a fiber-reinforced polyurethane/polyisocyanurate foam and blowing agent is carried out using a controlled liquid distributor (15) simultaneously over the entire width L. 12. The method according to claim 1 or 2, wherein the blowing agent consists of a physical and/or chemical expanding agent, preferably a combination of the two types. 13. The method of claim 12 wherein the physical expanding agent is selected from alkanes and cycloalkanes having at least 4 carbon atoms, dialkyl ethers, esters, ketones, acetals, fluoroalkanes, fluoroolefins having from 1 to 8 carbon atoms, and tetraalkylsilanes having from 1 to 3 carbon atoms in the alkyl chain, in particular tetramethylsilane, or mixtures thereof. 14. The method of claim 12 wherein the chemical expanding agent consists of water. 15. The method according to claim 13, wherein in step a) mixing (12) of the chemical components, a nucleating gas is introduced into at least one polyol compound, preferably using a static/dynamic mixer at a pressure of 20 to 250 bar, the nucleating gas is from 0 to 50% by volume of the polyol, preferably 0.05 to 20% by volume of the polyol. 16. The method according to claim 1 or 2, wherein in step a) mixing (12) the chemical components, the temperature of each of the polyurethane/polyisocyanurate reactants is between 10 and 40°C, preferably between 15 and 30°C. 17. The method according to claim 1 or 2, wherein in step a) an organophosphorus flame retardant, preferably triethyl phosphate (TEP), tris(2-chloroisopropyl) phosphate (TCPP), tris(1,3-dichloroisopropyl) phosphate ( TDCP), tris(2-chloroethyl) phosphate or tris(2,3-dibromopropyl) phosphate or a mixture thereof, or an inorganic flame retardant, preferably red phosphorus, expandable graphite, alumina hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate, sulfate derivatives calcium or cyanuric acid, or a mixture thereof. 18. The method according to claim 1 or 2, wherein the content of C _f fibers is from 7 to 15% by weight of the block of fiber reinforced foam. 19. A block of fiber-reinforced polyurethane/polyisocyanurate foam for a heat-insulating plate (30) of a sealed and heat-insulating tank, directly obtained in accordance with the method according to any one of paragraphs. 1-18, wherein the fiber-reinforced polyurethane/polyisocyanurate foam block is comprised of gas-storage cells, preferably having low thermal conductivity, and has a density of less than 50 kg⋅m ^-3 with a C _f fiber content of at least 4% by weight of the fiber-reinforced foam block , characterized in that the fibers are evenly distributed in the fiber-reinforced polyurethane/polyisocyanurate foam block so that the _Cf content varies by only ±35% in all regions or areas of said fiber-reinforced polyurethane/polyisocyanurate foam block. 20. Sealed and heat-insulating tank, consisting of a tank built into the supporting structure, containing a sealed and heat-insulating tank containing at least one sealed metal membrane, consisting of a plurality of metal strips or metal plates that may contain corrugations, and a heat-insulating plate (30) containing at least one heat-insulating barrier adjacent to said membrane, or tank type B or C as defined in the IGC Code, containing at least one thermal insulation board (30), characterized in that the thermal insulation board (30) contains a block of fiber-reinforced polyurethane/polyisocyanurate foam according to claim 19. 21. Vessel (70) for transporting a cold liquid product, comprising at least one housing (72) and a sealed and heat-insulating tank (71) according to claim 20, located in the housing.

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