EP3947503A1

EP3947503A1 - Polyurethane/polyisocyanurate foam block of a thermal insulation mass of a vessel, and preparation process thereof

Info

Publication number: EP3947503A1
Application number: EP20722374.4A
Authority: EP
Inventors: Guillaume De Combarieu; Bruno Deletre; Florian CLOUP
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2019-03-26
Filing date: 2020-03-16
Publication date: 2022-02-09
Also published as: SG11202110313QA; JP2022528319A; CN113614137A; WO2020193873A1; CN113614137B; FR3094449B1; KR20210146950A; FR3094449A1

Abstract

. The invention relates to a fibrous polyurethane/polyisocyanurate foam block (20) in which the foam block comprises, along its thickness E, two peripheral regions, i.e. an upper peripheral e=region extending from the upper face of the block to the other, lower peripheral region extending from the lower face of the block, said two regions each representing no more than 20% of the thickness E of the block and being separated by an intermediate region; and the upper and lower peripheral regions have a fiber density T_{f sup.} and T_f _inf., respectively, such that: 2/3 ≤ T_{f sup.} /T_{f inf.} ≤ 3/2; and the fiber density T_{f int.} in the intermediate region is lower than the densities in the peripheral regions, i.e.: T_{f int.} < T_{f sup.} and T_{f. int.} < T_{f inf.}

Description

Title of the invention: Polyurethane / polyisocyanurate foam block of a thermal insulation block of a tank and its preparation process

[0001] [The invention relates to blocks of polyurethane (PUR) and / or polyisocyanurate (PIR) foams mounted in a thermal insulation block which must have, given their specific applications,

very particular mechanical and thermal characteristics, while being as economical as possible to produce, said blocks of foam being used within a tank, integrated in a membrane structure (also called an integrated tank) or self-supporting / semi-supporting type A, B or C, used to accommodate extremely cold fluids, called cryogenic, such as in particular Liquefied Natural Gas (LNG) or Liquefied Petroleum Gas (LPG).

[0002] The present invention relates more particularly to a sealed and thermally insulating tank using such foams, a vessel equipped with at least one such tank, a method for loading / unloading such a vessel and a transfer system for a product. liquid contained in such a vessel.

[0003] The present invention also relates to a process for preparing these foam blocks from at least one polyisocyanate and at least one polyol.

[0004] PUR polyurethane foam is a cellular insulator, composed of fine cells which store a gas which may have low thermal conductivity. PUR foam is used in a large number of applications such as the automotive industry as flexible PUR foam or in thermal insulation as rigid PUR foam. The formation of polyurethane type foams is well known to those skilled in the art. Its formation involves a multi-component reaction between a polyol (compound carrying at least two hydroxy groups), a polyisocyanate (compound carrying at least two isocyanate — NCO functions) and an expanding agent, also designated by expression "blowing agent". This condensation reaction is in particular catalyzed by compounds with basic and / or nucleophilic characters such as tertiary amines or metal-carboxylate coordination complexes such as tin or bismuth salts. Polyols commonly used in

Manufacturing PUR foams are polyether polyols or polyester polyols. Thus, a large number of compounds are necessary for the formation of PUR foam.

[0005] Polyisocyanurate (PIR) and polyurethane / polyisocyanurate (PUR-PIR) foams are also used in the building industry (construction / renovation) and have the advantage of providing better fire-resistant properties as well as a higher compressive strength than PUR. The process for forming these foams is similar to the process for forming PUR foams. In fact, obtaining PUR, PIR and PUR-PIR foams depends on the ratio

isocyanate / polyol.

[0006] PUR, PIR and PUR-PIR foams are well known to those skilled in the art, nevertheless the addition of fibers involves specific technical problems, such as the need for good impregnation of the fibers, so that at the present time, there are no such foams exhibiting at least locally a relatively substantial amount of fibers.

[0007] Now, in the technical field specific to the use of such foams for a thermal insulation block of a tank, said block is subjected to

very cold temperatures on its face exposed to the internal space of the vessel, for example of the order of -160 ° C in the case of LNG, while the external space of the vessel, conventionally the hull of a ship , often has an ambient temperature much higher, at least equal, or even very widely

higher than that of ambient air or the sea considered at around 20 ° C.

[0008] Thus, the block of PUR, PIR and PUR-PIR foam used in the solid

thermal insulation of such a tank undergoes, during the loading of the extremely cold fluid, said cryogenic, a very significant temperature gradient in its thickness which causes heterogeneous contraction phenomena of the foam block. This heterogeneous contraction of the foam block induces a bimetallic effect which leads to a flexing of the block along its longitudinal axis - the two ends having a tendency to rise significantly - due to the non-uniform contraction of the block in the thickness. The foam block being conventionally fixed mechanically or by gluing, this deflection critically lowers the exploitable mechanical properties of the PUR, PIR and PUR-PIR foam block, or even locally the thermal properties of the thermal insulation block (integrating the foam block according to the invention).

This bimetallic effect or bending effect phenomenon of the foam block has been accentuated in recent years due to the fact that the thickness of the foam blocks forming the thermal insulation has been increased, sometimes very significantly. for such tanks housing a cryogenic liquid. In particular, when these tanks comprise a double thermal insulation layer, conventionally referred to as a “primary” and “secondary” layer (the so-called secondary layer being located furthest from the cryogenic liquid), the thickness E of the secondary thermal insulation has increased very significantly in recent structures, for example of the MARK type. Thus, the thickness E of the secondary thermal insulation layer has been reduced from 170 mm (millimeter) in a MARK III structure, to 300 mm in a MARK III Flex structure and then to 380 mm in a MARK III Flex + structure.

[0010] This bimetallic effect or this sagging of the thermal insulation layer

secondary has particularly harmful structural consequences on the thermal insulation block, of a sealed and thermally insulating tank, when the thickness of this secondary layer increases significantly relative to the thickness of the primary thermal insulation layer.

Structures such as those described in the documents are known

FR 2882756, WO 2017/202667 and JP 2005225945 but none provides a satisfactory solution to the particular technical problems set out above.

[0012] At the present time, there is no block of polyurethane and / or polyisocyanurate foam, fiber-reinforced or non-fiber, making it possible to respond effectively to this problem, in other words a PUR, PIR and PUR foam block. PIR exhibiting thermomechanical stability between its initial state (in a homogeneous thermal environment) and its operating state, namely when it is used in a vessel containing a cryogenic liquid. To overcome this problem of distortions or geometric instability between these two states of the foam block, is currently produced specially shaped foam blocks, including incorporating notches, or reduced dimensions, of so as to limit the thermal distortion of each of the (small) volume elements or (small) foam blocks within an acceptable range. The need to produce these small foam blocks entails a great number of operations for cutting, placing and joining them to one another, which represents substantial costs. Moreover, the presence of numerous expansion joints very significantly degrades the thermal performance of the tank.

[0014] In addition, in certain embodiments of the insulation blocks

thermal tanks, the existing foam blocks are placed in a container, typically a box, made of wood plywood, for example of fir, birch or beech. In these embodiments, the lower and upper faces of the foam block are glued to the internal surface of the container so as to correctly position the blocks. However, during cooling, that is to say when the tank is in use / service condition (the tank containing a cryogenic liquid), the central part or at the heart of the block of foam then contracts significantly. that the upper and lower zones of the block are constrained by their bonding to the internal walls of the container. Because the thermal contraction coefficient of foam is much higher than that of plywood, this phenomenon leads to a distortion of the shape of the block, when it is in use / service condition, the side ends of which have a profile substantially circular, arch-shaped) or counter-arc (thus creating empty spaces between the foam block and its adjacent neighbors or the side walls of the plywood container. These foam voids can lead to appearance of unwanted thermal convection phenomena because it deteriorates the thermal insulation qualities of the tank insulation block.

The present invention also intends to provide a solution to this problem specific to certain modes of use of the block of polyurethane (PUR) and / or polyisocyanurate (PIR) foam. It is in this context that the applicant has succeeded in developing a process for the production of polyurethane (PUR) foams and / or

polyisocyanurate (PIR) containing fibers in significant quantity allowing both obtaining a fiber foam having excellent mechanical and thermal properties, while maintaining, over the entire foam block, the integrity of its shape / structure, when the block is in use condition, that is to say in a very different thermal environment between its two faces, upper and lower.

[0017] The present invention thus intends to remedy the shortcomings of the state of

technique by proposing a particularly effective solution for industrially obtaining a fiber-reinforced PUR / PIR foam, possibly of (very) large dimensions, whose mechanical / thermal properties are optimal and at least substantially similar between its initial state - at rest, the block of foam in a substantially homogeneous thermal environment - and its state of use / service in which the foam block is in a very heterogeneous thermal environment, the temperature difference between its upper face (content side of the tank) and its lower face (side outside the tank), considered according to the thickness of the block, being at least equal to 80 ° C, or even at least equal to 100 ° C.

It was discovered by the Applicant, after various studies and analyzes, a block of polyurethane (PUR) and / or polyisocyanurate (PIR) foam, and its preparation, capable of solving the technical problems associated with the very modification. significant of the thermal environment of the PUR / PIR foam block during use.

[0019] Advantageously, it is also possible, according to a preferred embodiment, to very significantly reduce the production cost of such a fiber-reinforced foam by very significantly reducing the loss of material from the foam block, conventionally necessary according to the prior art when cutting the foam block to obtain the desired dimensions (parallelepiped).

[0020] Thus, the present invention relates to a foam block of

polyurethane / polyisocyanurate fiber from a thermal insulation block of a sealed and thermally insulating tank, the density of the foam block fiber is between 30 and 300 kg / m ³ , the foam block of

fiber-reinforced polyurethane / polyisocyanurate having an average fiber density Tf of between 1% and 60% by mass of fibers, and having a width L of at least ten centimeters, advantageously between 10 and 500 centimeters, and a thickness E, from the lower face of said block up to its upper face, of at least ten centimeters, advantageously between 10 and 100 centimeters, the block of fibered polyurethane / polyisocyanurate foam being composed of cells storing a gas, advantageously of low thermal conductivity.

The block of fibered polyurethane / polyisocyanurate foam consists, at least 95% by mass of said block, of cells storing a gas, advantageously of low thermal conductivity, of the foam

polyurethane / polyisocyanurate and fibers.

The foam block according to the invention consists (only) of polyurethane (PUR) and / or polyisocyanurate (PIR) foam, fibers, which are preferably of a single nature such as glass fibers , and gas trapped in the cells, and optionally a minimal portion, for example, of fillers or other functional adjuvants, or for the latter a maximum of 5% by mass, or even preferably a maximum of 2% or of 1% by mass of the foam block according to the invention (the foam block of

at least 98% or 99% by mass of said block, at least 98% or 99% by mass of said block, of cells storing a gas, foam

polyurethane / polyisocyanurate and fibers). Indeed, the foam block according to the invention is obtained:

- in a single foam preparation operation (mixing of

reaction ingredients, optionally fillers / adjuvants, with the fibers), preferably in a double strip laminator (DBL);

- in the above operation completed by a cutting operation,

conventionally on the upper face of the block, for bonding a peripheral zone as described below.

The foam block according to the invention is characterized in that: - The foam block comprises, according to its thickness E, two peripheral zones, one called upper extending from the upper face of the block and the other called lower extending from the lower face of the block, these two zones each representing at most 20% depending on the thickness E of the block and being separated by a so-called intermediate zone; and

the peripheral zones, upper and lower, respectively have a fiber density Tf sup. and Tf inf. such that: 2/3 <(Tf sup. / Tf inf.) £ 3/2; and

- the fiber density Tnnt. of the intermediate zone is lower than the densities of the peripheral zones, namely: Tnnt. <Tf sup. and Tnnt. <Tf inf ..

The present invention is intended to apply in particular, but not

exclusively, in the case where the foam block is installed at the level of the secondary layer, conventionally referred to as the “secondary”. In this application, preferably, the foam block has a thickness of at least twenty-five (25) centimeters (cm), even more preferably at least 30 or 35 cm.

The terms "upper" and "lower" are understood to mean a meaning or a direction given to the foam block once the latter is in position in the thermal insulation block of a tank. Thus, the part or the upper face of the foam block is that located near or on the side of the container of the tank, when the thermal insulation block is placed in the tank, while the lower part or face of the block of foam is that located towards or on the side of the exterior of the tank, that is to say in particular towards the hull of a ship in the case where the tank is integrated or mounted in a transport vessel and / or storage of cryogenic liquid.

It is thus understood that, during the manufacture or preparation of the foam block, these notions or terms of "upper" or "lower" do not yet have any meaning since the foam block is not yet installed in the thermal insulation block of a tank. In other words, we can perfectly prepare the foam blocks according to the invention so that they are obtained, at the outlet of their preparation / production line, with a position opposite to that of their final assembly / assembly in the solid mass thermal insulation of a tank. The expression "according to its thickness E" is understood to mean relative to the various peripheral, intermediate or even central / central zones as described below, the fact that these zones each represent a volume of the block of polyurethane foam (PUR ) and / or polyisocyanurate (PIR) fiber considered by taking a section along the section of thickness E, as shown in particular in Figures 3 and 4, to form a block portion having the same width L and the same length - only the thickness being different - than the foam block according to the invention.

The expression “cells storing a gas” is understood to mean the fact that the polyurethane / polyisocyanurate foam has closed cells enclosing a gas, preferably exhibiting low thermal conductivity, originating from a gas injected during a step of nucleation of the reaction mixture or originating, directly or indirectly, from the chemical or physical blowing agent.

The term "fiber (s)" or the expression "fiber reinforcement" is understood to mean the fact that the fibers can be in two distinct forms:

- or in the form of at least one fabric of fibers, in which the fibers are perfectly aligned in at least one direction, in other words the fibers have at least one preferred direction of fibers. The expression "fiber fabric" per se refers to a clear technical definition known to those skilled in the art,

- or in the form of at least one mat of fibers, in which the fibers have no defined orientation, in other words these fibers are oriented isotropically essentially along the main plane of the layer of the mat. Again, the expression "fiber mat" per se refers to a clear technical definition known to those skilled in the art.

[0030] According to one embodiment, the expression "gas

(advantageously) at low thermal conductivity "the gas coming from the blowing agent, or by chemical reaction of the latter when this agent is said to be" chemical ", conventionally carbon dioxide (CO2) when the chemical blowing agent consists of water or by a physical blowing agent such as by example dinitrogen (N2), oxygen (O2), carbon dioxide, hydrocarbons, chlorofluorocarbons, hydrochlorocarbons,

hydrofluorocarbons, hydrochlorofluorocarbons, and mixtures thereof, as well as the corresponding alkyl ethers. Physical blowing agents such as molecular nitrogen N2, oxygen O2 or CO2 are found in gas form. These gases are dispersed or dissolved in the liquid mass of copolymer, for example under high pressure, using a static mixer. By depressurizing the system, nucleation and growth of bubbles generates cellular structure.

The expression "average density Tf in fibers" is understood to mean the fiber density expressed as mass of fibers relative to the total mass of the block of fiber-reinforced foam, without considering the local percentages (within the block) which vary from these fibers.

[0032] Thus, the fiber-reinforced foam block is compatible with use in tanks integrated into a supporting structure but also self-supporting / semi-supporting tanks of type A, B or C according to regulations (IMO)

IGC, that is to say as an external insulation associated with self-supporting tanks for the storage and / or transport of very cold liquids such as LNG or LPG.

Finally, the thermal properties of the block of fiber foam are at least

equal to those of the blocks of non-fiber foam of the state of the art, more precisely the block of foam has, in the thickness E, a thermal conductivity of less than 30 mW / mK (milliwatt per meter per Kelvin), i.e. 0 , 03 W / mK, preferably less than 25 mW / mK, even more preferably less than 23 mW / mK, measured at 20 ° C, and a thermal conductivity of less than 20 mW / mK when the top face of the block is found at -160 ° C, the foam block then being in operating condition, the tank in which it is housed containing LNG.

[0034] Other advantageous features of the invention are presented

succinctly below:

Preferably, the aforementioned two peripheral zones each represent at most 10% depending on the thickness E of the block. According to a preferred embodiment of the invention, the intermediate zone comprises a central zone, surrounded by two middle zones, representing at most 20% according to the thickness E, preferably at most 10% according to the thickness E, the fiber density Tf ¥ n. of this central zone being at least one and a half times greater than that of the median zones Tf med. , let Tf ¥ n. ³ 1, 5 Tf med ..

This embodiment is shown in Figure 4 attached and allows

to address more specifically the problem of foam shrinkage at the core, that is to say in the central zone, while avoiding the bimetal phenomenon thanks to the peripheral zones of higher fiber density.

According to another characteristic specific to this embodiment, the fiber density Tf ¥ n. of the central zone is defined relative to the fiber density Tf sup. and Tf inf. peripheral areas, upper and lower, such that 0.5 <Tf cen. / (Tf below OR Tf above) £ 2.

Preferably, the density of the block of fiber-reinforced foam is between 50 and 250 kg / m ³ , preferably between 90 and 210 kg / m ³ . It should be noted here that for the foam blocks used in a self-supporting tank (types B, C) or semi-supporting (type A), the density range of the fiber foam block is preferably between 30 and 90 kg / m ³ while in the case of a membrane, the even preferred density range is between 90 and 210 kg / m ³ .

Advantageously, at least 60%, preferably at least 80%, of the aforesaid cells storing a gas, advantageously of low thermal conductivity, have an elongated or stretched shape along an axis parallel to the axis of a thickness E of the block of fiber-reinforced polyurethane / polyisocyanurate foam.

[0041] According to one possibility offered by the invention, the fibers consist of glass fiber or of basalt fiber, preferably of glass fiber.

[0042] Preferably, the fibers are long to continuous fibers.

The expression "the fibers being long to continuous" (or "

long to continuous fibers') the fact that the fibers, or where appropriate an agglomeration of a set of fibers (fibers bonded or fixed to each other), all present - i.e. at least 90% of the fibers, considered alone or agglomerated forming the equivalent of a single fiber, in total mass of said fibers - a length of at least five (5) centimeters (cm).

Preferably, the average density of Tf fibers is between 2% and 25%, preferably 6% and 20%.

[0045] Preferably, the foam block according to the invention is in a parallelepipedal or cubic shape.

It is understood here that this block of foam, having such a parallelepipedal or cubic shape, may have one or more local protuberances, for example in the form of the anchors presented below, or even conversely the portions empty or hollow, while still being able to be qualified as parallelepiped or cubic.

Advantageously, the lower face and / or the upper face of said block

present (s) anchors capable of engaging with a means for engaging the thermal insulation block (not shown in the appended figures) in order to fix or anchor the foam block to said block, preferably said anchors being made up of a material other than the foam or the fibers.

These anchors are advantageously metallic elements (these

anchors can also be made of plastic / polymers or composites combining one or more polymers with ceramic and / or metallic materials), for example having a hooking tab, L-shaped, or a slot / opening for example L of so as to engage with an element or part of the thermal insulation block enclosing or housing the block of fiber foam. This part of the thermal insulation block may consist of a metallic membrane sealing the container, for example of stainless steel or manganese-based, in the case of a membrane tank or of a vapor barrier (having the function of technique of ensuring a seal to the surrounding environment outside the tank) in the case of self-supporting or semi-supporting tanks of type A, B or C. In a possibility offered by the invention, this element or this part of the mass of thermal insulation (in a membrane tank) has a notch or the like intended to allow engagement with a portion of an anchor for maintenance or mechanical restraint from the fiber-reinforced foam block to the other thermal insulation block elements. Of course, these anchors may also have the function of anchoring the foam block to the hull, in the case of a membrane tank, to the self-supporting structure in the case of a self-supporting tank of type A, B or C , it being understood that these anchors are then those present on the underside of the foam block.

In the context of the present invention, these anchors are inserted at least in part in the fiber reinforcements, those constituting the lower or upper layer of the fiber reinforcement stack, so as to allow their location on the faces once the block of foam has been prepared / finished, without however protruding from said face.

Advantageously, the block of fiber foam according to the invention comprises a flame retardant in a proportion of between 0.1% and 5% by weight, of the organophosphorus type, advantageously triethylphosphate (TEP), tris (2- chloroiso-propyl) phosphate (TCPP), tris (1, 3-dichloroisopropyl) phosphate (TDCP), tris (2-chloroethyl) phosphate or tris (2,3-dibromopropyl) phosphate, or a mixture of these , or of the inorganic flame retardant type, advantageously red phosphorus, expandable graphite, an aluminum oxide hydrate, an antimony trioxide, an arsenic oxide, an ammonium polyphosphate, a calcium sulfate or cyanuric acid derivatives, a mixture thereof.

The invention also relates to a sealed and thermally insulating tank integrated into a supporting structure, said tank consisting of:

- a tank integrated into a supporting structure comprising a sealed and thermally insulating tank comprising at least one sealed metal membrane composed of a plurality of metal strakes or metal plates which may include corrugations and a thermally insulating mass comprising at least one adjacent thermally insulating barrier to said membrane, or

- a type A, B or C tank according to the definition given by the IGC code comprising at least one thermally insulating block. The tank according to the invention is characterized in that the thermally insulating mass comprises a plurality of blocks of foam

fiber-reinforced polyurethane / polyisocyanurate as described briefly above.

The expression "IGC code" is understood to mean the "international collection of rules relating to the construction and equipment of ships transporting liquefied gases in bulk", well known to those skilled in the art, at l 'like the types B and C of tanks cited, or in English “International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk”.

It will be noted that one can use, in particular in the IGC code, the expression "membrane tank (or tank)" instead of the expression "integrated tank" to designate the same category of tanks, fitted in particular to tankers transporting and / or storing at least partly liquefied gas. The “membrane tanks” are integrated in a supporting structure while the tanks of type A, B or C are said to be self-supporting or semi-supporting (type A specifically).

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 thermally insulating tank as described briefly above, arranged in the hull or mounted on said vessel when said tank is of type A, B or C according to the definition given by the IGC code.

Advantageously, in the case where the tank consists of a tank integrated into a supporting structure (membrane tank), such a vessel comprises at least one sealed and insulating tank as described above, said tank comprising two barriers of 'successive sealing, one primary in contact with a product contained in the tank and the other secondary disposed between the primary barrier and a supporting structure, preferably constituted by at least part of the walls of the vessel, these two barriers of sealing being alternated with two thermally insulating barriers or a single thermally insulating barrier arranged between the primary barrier and the supporting structure.

Such tanks are conventionally designated as integrated tanks according to the code of the International Maritime Organization (IMO), such as by example of type NO tanks, including types NO 96 ^® , NO 96L03 ^® , NO

96L03 + ^® or NO 96 MAX ^® , or MARK III ^® , MARK III ^® Flex or FLEX +, from

preferably NO type tanks.

Preferably, the tank, called membrane type or type A, B or C,

contains Liquefied Natural Gas (LNG) or Liquefied Gas (GL).

The invention also relates to a transfer system for a cold liquid product, the system comprising a vessel as defined above, insulated pipes arranged so as to connect the tank installed in the hull of the vessel to a control unit. floating or terrestrial storage and a pump for driving a flow of cold liquid product through insulated pipelines from or to the floating or terrestrial storage unit to or from the ship.

The invention also relates to a method for loading or unloading a ship as defined above, in which a cold liquid product is conveyed through isolated pipes from or to a floating or terrestrial storage unit towards or from the ship.

The present invention also relates to the process for preparing a block of polyurethane / polyisocyanurate foam fiber from a thermal insulation block of a sealed and thermally insulating tank as described

succinctly above, said preparation process being characterized in that it comprises the steps:

a) a mixture of chemical components necessary for obtaining a polyurethane / polyisocyanurate foam, said components comprising reagents for obtaining polyurethane / polyisocyanurate, optionally at least one reaction catalyst, optionally at least one emulsifier, and at least one blowing agent,

b) impregnation, by gravitational flow of the aforesaid mixture of

chemical components, of a plurality of fiber reinforcements, said fiber reinforcements being arranged in superimposed layers and having varying fiber densities, in which the fiber reinforcements extend essentially in a direction perpendicular to the direction of said flow

gravitational, c) formation and expansion of the polyurethane / polyisocyanurate fiber foam,

in which the expansion of the fiber-reinforced polyurethane / polyisocyanurate foam is said to be by free expansion, either without the stress exerted by a volume of closed section on at least one face, preferably the upper face, or in which the expansion of the fiber-reinforced polyurethane / polyisocyanurate foam is physically constrained by walls of a double strip laminator, preferably is physically constrained by the walls of a double strip laminator forming a tunnel of rectangular section with a distance between the walls disposed laterally equal to L and a distance between the walls arranged horizontally equal to E, thus enclosing the expanding fiber foam so as to obtain the aforesaid block of foam

polyurethane / polyisocyanurate fiber.

The expression "cream time" is understood to mean the time required, to

counting the mixture of chemical components, so that the latter start the polymerization reactions and therefore the mixture of components starts step c) of expansion and crosslinking (= formation of the PUR / PIR fiber foam). This cream time is well known to those skilled in the art. In other words, the cream time is the time elapsed until the mixture turns white under the action of the nucleation of the bubbles (cells storing a gas) and the expansion of the foam after mixing the chemical components. at room temperature. The cream time can be determined visually or with the aid of an ultrasonic sensor detecting a variation in thickness indicating the formation of foam.

By the expression "the fiber reinforcements extend essentially in a direction perpendicular to the direction of the gravitational flow of the mixture of chemical components" is meant the fact that these fiber reinforcements are in the form of a thin layer spreading, during step b) of impregnation, along a plane perpendicular to the direction

flow of said mixture of components. Thus, as can be seen in Figure 1, the plurality of fiber reinforcements, having a width L and arranged in superimposed layers, are driven in a longitudinal direction I while the mixture of chemical components is deposited on the fiber reinforcements from a distributor allowing / allowing the gravitational flow of the mixture of chemical components. In other words, the mixture of chemical components, possibly exiting under pressure from the dispenser, falls under the effect of at least its own weight on the stacked fiber layers, thus impregnating these fiber reinforcements from the upper layer to the lower layer. .

[0064] According to one embodiment of the invention, in the case where the expansion of

step c) is carried out by free expansion, at least one of the zones

peripherals, preferably the upper zone, is formed independently and fixed, once a cutout on at least the free expansion face has been made, to form said block of foam.

The use, in the composition according to the invention, of a swelling agent

chemical, can be coupled with that of a physical blowing agent. In this case, the physical blowing agent is preferably mixed in liquid or supercritical form with the foamable (co) polymer composition and then converted to the gas phase during the PUR / PIR foam expansion step.

Chemical and physical blowing agents are well known to those skilled in the art who selects both, in the appropriate amounts, depending on the PUR / PIR foam he wishes to obtain.

By polyols is meant any carbon structure bearing at least two

OH groups.

Obtaining PUR, PIR and PUR-PIR foams depending on the ratio

isocyanate / polyol, a PUR, PIR or PUR-PIR foam will be obtained according to this ratio. When the ratio between a polyol component and an isocyanate component is:

- between 1: 1 and 1: 1, 3 a PUR polyurethane foam will be obtained,

- between 1: 1, 3 and 1: 1, 8 we will obtain a PUR-PIR polyurethane foam,

- between 1: 1, 8 and 1: 2.8, a PIR polyurethane foam will be obtained. Polyisocyanates suitable for the formation of PUR, PIR and PUR-PIR foam are known to those skilled in the art and include, for example, aromatic, aliphatic, cycloaliphatic, arylaliphatic polyisocyanates and their mixtures, advantageously aromatic polyisocyanates.

Examples of polyisocyanates suitable in the context of the present invention include aromatic isocyanates such as the 4,4'-, 2,4'- and 2,2'- isomers of diphenylmethane diisocyanate (MDI), any compound resulting from of the

polymerization of these isomers, toluene 2,4- and 2,6-diisocyanate (TDI), m- and p-phenylene diisocyanate, naphthalene-1, 5-diisocyanate; aliphatic, cycloaliphatic, arylaliphatic isocyanates such as 1, 6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (H12MDI), 1, 4-cyclohexane diisocyanate (CHDI) , the

bis (isocyanatomethyl) cyclo-hexane (H6XDI, DDI) and tetramethyxylylene diisocyanate (TMXDI). It is also possible to use any mixtures of these diisocyanates. Advantageously, the polyisocyanates are the 4,4'-, 2,4'- and 2,2'- isomers of diphenylmethane diisocyanate (MDI).

In general, it is known to add, during the formation of PUR, PIR or PUR-PIR foams, to the mixture comprising the polyol, the polyisocyanate and the blowing agent, a reaction catalyst which may for example be chosen from tertiary amines, such as N, Ndimethylcyclohexylamine or N, N-dimethylbenzylamine or from organometallic compounds based on bismuth, potassium or tin.

[0072] According to a preferred embodiment of the invention, advantageously, the

positioning of the tunnel walls of the double strip laminator (DBL) is defined so that the expansion stress of the foam

fiber-reinforced polyurethane / polyisocyanurate leads to a volume of fiber-reinforced polyurethane / polyisocyanurate foam, at the outlet of the double-strip laminator, representing between 85 and 99%, preferably between 90% and 99%, of the expansion volume of this same foam of polyurethane / polyisocyanurate fiber in the case of free expansion, without the stress of the walls of such a double strip laminator. In this case, a foam is obtained, the cells of which, ovoid in shape, are preferably oriented along the axis E, leading to advantageous properties of resistance to crushing in this direction E (measured according to the ISO 844 standard), combined with the properties already described in the plane normal to this axis E. Tests and experiments were carried out by the applicant to determine the fields , broad and preferred, mentioned above but are not presented here for the sake of clarity and conciseness.

Thanks to the aforesaid specific parameterization of the stress on expansion of the fiber-reinforced PUR / PIR foam in a DBL, on the one hand, a block of fiber-reinforced PUR / PIR foam is obtained in which at least 60%, generally more than 80% or even more than 90%, cells storing a gas with low thermal conductivity extend longitudinally along an axis parallel to the axis of the thickness E of the foam block and we contribute, in addition to the specific choices related to characteristics of the fiber reinforcements and the viscosity of the mixture of chemical components, perfect homogeneity of the block of fiber foam. These two characteristics - orientation of the cells & homogeneity of the Tf rate of fibers in the block according to the different zones, peripheral or central - make it possible to obtain a block of fiber foam with excellent mechanical properties according to the thickness E (compressive strength ) and in a plane normal to the direction of the thickness (tensile strength and low coefficient of thermal contraction).

[0074] The elongated or stretched shape can be defined by an extended shape in

length, that is to say it has one dimension: its length, greater than its other dimensions (width and thickness).

[0075] According to another embodiment offered by the invention, the expansion of the

Polyurethane / polyisocyanurate fiber foam is free, ie without the stress exerted by a closed section volume.

Here, unlike the embodiment of the preparation according to the invention using a DBL, the preparation of the polyurethane / polyisocyanurate foam is said to be "free expansion" insofar as the expansion of the fiber-reinforced foam is not constrained on at least one side or on at least one expansion face so that the swelling of the fiber-reinforced foam is free on this side or this face, unlike a mold defining a volume finished.

Conventionally, free expansion is achieved by omitting the cover (upper) while the side walls prevent foam overflow to the sides and the foam naturally swells upwards,

possibly beyond the upper ends of these side walls.

[0077] Advantageously, following the step of free expansion of the foam of

polyurethane / fiber-reinforced polyisocyanurate, said fiber-reinforced foam is cut to obtain the aforementioned block of polyurethane / fiber-based polyisocyanurate foam.

According to one possibility offered by the invention, not shown in the appended figures, just after the step of impregnating the fiber reinforcements, the mixture of components and at least the blowing agent impregnating them is applied to the mixture. fibers, a pressure application system (which may for example be a roller system, of the type designated "nip roll" in English) intended to apply pressure to the upper face of the assembly consisting of the aforesaid mixture and the fibers. This pressure system makes it possible on the one hand to plan the upper face of this assembly and, by the pressure exerted on the assembly, helps to promote the impregnation of the fibers in the aforesaid mixture. This pressure system may consist of a single or a double roller, the relative positions of which, above the liquid assembly, and possibly below the foam support, are adjusted in such a way that the liquid assembly is forced to spread out in a perfectly uniform manner. Thus, in doing so, one obtains, at any point of the section defined by the spacing between the two rollers or of the upper roller and the conveyor belt, an equivalent quantity of the liquid assembly. In other words, the main object of this pressure system is to supplement the liquid dispensing device in that it helps to standardize, in thickness / width, the liquid assembly before most of its expansion.

Preferably, the dynamic viscosity h of the aforesaid mixture of components is between 30 mPa.s and 3000 mPa.s (or 0.03 Pa.s and 3 Pa.s), preferably between 50 mPa.s and 1500 mPa.s (or 0.05 Pa.s and 1.5 Pa.s) at ambient temperature (25 ° C) and atmospheric pressure (1015 mPa). The dynamic viscosity of the mixture of components can be determined using a viscometer, for example of the Brookfield type, or a rheometer, for example using the ISO 2555 standard.

In general, it is understood that the object of the present invention uses materials / products accessible or available on the market so that their properties, in particular those relating to their densities or viscosities (dynamic), are available. in the specifications for

materials / products considered.

Advantageously, at least 60% of the aforesaid cells storing a gas, advantageously of low thermal conductivity, have an elongated or stretched shape along an axis parallel to the axis of a thickness E of the block of polyurethane foam / fibered polyisocyanurate ;

Even more advantageously, at least 80%, preferably at least 90%, of the aforesaid cells storing a gas, advantageously of low thermal conductivity, have an elongated or stretched shape along an axis parallel to the axis of a thickness E of the foam block of

polyurethane / polyisocyanurate fiber;

It is of course here that this characteristic linked to the elongated shape of the cells storing a gas, advantageously of low thermal conductivity, and their rate / proportion in the block according to the invention is more particularly directed within the framework of the setting. implementation of the preparation process with a DBL, but it is absolutely not limited to this case. Indeed, in the case of free expansion, more specifically when there is no

upper wall / cover constraining the expansion of the fiber-reinforced foam, such a preferential orientation of the cells storing a gas, advantageously of low thermal conductivity, is also obtained.

Preferably, the (reinforcements of) fibers are arranged over a whole width L and step b) of impregnation of the fibers with the mixture of components, to obtain a polyurethane / polyisocyanurate foam, and a blowing agent operates via a controlled liquid distributor, simultaneously over the entire width L; The term "simultaneously" is understood to mean the fact that the liquid mixture (reactants and at least the swelling agent) reaches the fibers, over a section of width L, at the same time all along this section so that the impregnation of the various fiber reinforcements begins or takes place, depending on the thickness (or the height) of the foam block and for the same section of width, at the same time or at the same speed.

[0087] Advantageously, the blowing agent consists of an expanding agent

physical and / or chemical, preferably a combination of the two types.

Preferably, the physical expansion agent is chosen from alkanes and cycloalkanes having at least 4 carbon atoms, dialkyl ethers, esters, ketones, acetals, fluoroalkanes, fluoroolefins having between 1 and 8 carbon atoms and tetraalkylsilanes having between 1 and 3 carbon atoms in the alkyl chain, in particular tetramethylsilane, or a mixture thereof.

In this hypothesis, by way of example of compounds, it could be

propane, n-butane, isobutane, cyclobutane, n-pentane, isopentane, cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether, methyl butyl ether, methyl formate, acetone and fluoroalkanes; the fluoroalkanes being chosen are those which do not degrade the ozone layer, for example

trifluoropropane, 1, 1, 1, 2-tetrafluoroethane, difluoroethane and

heptafluoropropane. Examples of fluoroolefins include 1 -chloro-3,3,3-trifluoropropene, 1, 1, 1, 4,4,4-hexafluorobutene (for example HFO FEA1100 sold by the company Dupont).

[0090] According to a preferred embodiment of the invention, the blowing agent

physical chosen is 1, 1, 1, 3,3-pentafluoropropane, or FIFC-245fa,

(marketed by the company Floneywell), 1, 1, 1, 3,3-pentafluorobutane, or 365mfc, (for example solkane® 365mfc marketed by the company Solvay), 2,3,3, 3-tetrafluoroprop-1 -ene, 1, 1, 1, 2,3,3, 3-heptafluoropropane (also internationally referred to as FIFC-227ea, e.g.

marketed by the company Dupont), 1, 1, 1, 4,4,4-hexafluorobutene (for example FIFO FEA1100 marketed by the company Dupont), trans- 1 - chloro-3,3,3-trifluoropropene (solstice LBA - Honeywell company) or a mixture of these.

Advantageously, the chemical blowing agent consists of water.

Advantageously, during step a) of mixing chemical components, nucleation gas is incorporated into at least one polyol compound, preferably using a static / dynamic mixer at a pressure between 20 and 250 bars, the nucleation gas representing between 0 and 50% by volume of polyol, preferably between 0.05 and 20% by volume of the volume of polyol;

[0093] Preferably, during step a) of mixing the chemical components, the temperature of each of the reagents for obtaining

polyurethane / polyisocyanurate is between 10 ° C and 40 ° C, preferably between 15 ° C and 30 ° C;

[0094] Preferably, according to a preferred embodiment of the invention, the

final mixing of the streams of polyols, isocyanate and / or blowing agent takes place in a mixing head at low pressure (<20 bar) or high pressure (> 50 bar) using a dynamic or static mixer.

According to one possibility offered by the invention, is further added to the mixture, in step a), an organophosphorus flame retardant, advantageously triethylphosphate (TEP), tris (2-chloroiso-propyl) phosphate ( TCPP), tris (1, 3- dichloroisopropyl) phosphate (TDCP), tris (2-chloroethyl) phosphate or tris (2,3-dibromopropyl) phosphate, or a mixture thereof, or a flame retardant inorganic, preferably red phosphorus, expandable graphite, aluminum oxide hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate, calcium sulfate or cyanuric acid derivatives, a mixture of these.

It is also conceivable that the flame retardant uses

diethyl ethane phosphonate (DEEP), triethyl phosphate (TEP), propyl phosphonate dimethyl (DMPP) or cresyl diphenyl phosphate (DPC).

This flame retardant, when it is present in the composition according to the invention, is found in an amount of between 0.01% and 25% by weight of the PUR / PIR foam. The description which follows is given purely by way of illustration and not by way of limitation with reference to the appended figures, in which:

[0099] [Fig.1] is a schematic view illustrating the different steps of the process for preparing a block of fiber-reinforced PUR / PIR foam according to the invention.

[0100] [Fig.2] is a schematic representation of an embodiment of a controlled liquid dispenser according to the invention.

[0101] [Fig.3] is a schematic sectional view of a foam block according to a

embodiment of the invention in which the areas are visible

peripherals as well as the intermediate zone.

[0102] [Fig.4] is a schematic sectional view of a foam block according to a

another embodiment of the invention in which the peripheral zones as well as the intermediate zone are visible, the latter having two middle zones sandwiching a central zone.

[0103] [Fig.5] is a schematic view of two sets of thermal insulation panels, fixed one on the other, respectively forming a primary space and a secondary insulation space for a tank, these panels being constituted by a plurality of blocks of polyurethane / polyisocyanurate foam according to the invention.

[0104] [Fig.6] is a partial view of a block of foam according to the invention in which a plurality of anchors have been placed during its preparation so as to allow the fixing or anchoring of said block of foam .

[0105] [Fig.7] illustrates one embodiment of an anchor, visible in a schematic section, capable of being inserted into a block of foam according to the invention.

[0106] [Fig.8] is a cut-away schematic representation of an LNG vessel tank, in which are installed the two sets of thermal insulation panels of the type shown in Figure 7, and a loading / unloading of this tank.

Preferably, the preparation of the fiber-reinforced PUR / PIR according to the invention is carried out in the presence of catalysts making it possible to promote the isocyanate-polyol reaction. Such compounds are described for example in the document of the state of the technique entitled "Kunststoffhandbuch, volume 7, Polyurethane", Imprimerie Cari Hanser, 3rd edition 1993, chapter 3.4.1. These compounds include amine based catalysts and organic compound catalysts.

[0108] Preferably, the preparation of the block of fibered PUR / PIR foam 20 according to the invention is carried out in the presence of one or more stabilizers intended to promote the formation of regular cellular structures during the formation of the foam. These compounds are well known to those skilled in the art and, by way of example, mention may be made of foam stabilizers comprising silicones such as siloxane-oxyalkylene copolymers and other organopolysiloxanes.

[0109] Those skilled in the art know the amounts of stabilizers, between 0.5% and 4% by weight of the PUR / PIR foam, to be used depending on the reagents envisaged.

[0110] According to one possibility offered by the invention, during step a) of the preparation process, the mixture of chemical components can include plasticizers, for example polybasic esters, preferably dibasic, carboxylic acids with monohydric alcohols , or consist of polymeric plasticizers such as polyesters of adipic, sebacic and / or phthalic acids. The person skilled in the art, depending on the reagents used, knows what quantity of plasticizers envisaged, typically from 0.05% to 7.5% by weight of the polyurethane / polyisocyanurate foam.

[0111] Organic and / or inorganic fillers, in particular reinforcement fillers, can also be considered in the mixture of chemical components such as siliceous minerals, metal oxides (for example kaolin, oxides of titanium or of iron) and / or metal salts. The amount of these fillers, if present in the mixture, is

conventionally between 0.5% and 15% by weight of the PUR / PIR foam.

[0112] It should be noted that the present invention does not intend here to add a

technical training in the formation of a PUR / PIR foam, both in terms of the nature of the essential chemical components and optional functional agents as well as their respective amounts. Those skilled in the art know how to obtain different types of fiber-reinforced PUR / PIR foam and the present preparation relates, from a specific choice of characteristics of the fiber reinforcements, in particular the fiber density in the various fiber reinforcements, and an equally specific choice of the foam for the impregnation of said reinforcements.

[0113] Thus, the present invention, as explained here, is not primarily aimed at a new chemical preparation of fiber-reinforced PUR / PIR foam but rather a new block of fiber-reinforced PUR / PIR foam 20 in which, thanks to very specific fiber density distribution depending on the thickness or height of the block 20, this block of fiber foam 20 does not undergo any sagging or any

deformation of its general parallelepipedal shape / structure other than a slight contraction of its dimensions by a constant factor in all its directions, and preferably no shrinkage at the core of the foam block 20 likely to lead to possible phenomena of thermal convection.

[0114] Thus, as can be seen in FIG. 1, a plurality of fiber reinforcements 10 are unwound and brought in parallel alignment with one another on or above a conveyor belt 11 intended to lead these reinforcements 10. and the PUR / PIR foam-forming components. In fact, the impregnation of the fiber reinforcements 10 is carried out, in the context of a preferred method of preparation of the block of fiber foam 20 of the present invention, by gravity, that is to say that one sinks , from a liquid distributor located above the fiber reinforcements 10, the mixture 12 of chemical components, blowing agent (s) and any other functional agents used to obtain the PUR foam / PIR, directly on the fibers 10.

Thus, the aforesaid mixture 12 must impregnate all of the layers of fiber reinforcements 10, whether for the latter they are several mats or several fabrics, in a very homogeneous manner, over the course of the cream time. t _c so that the start of the expansion of the PUR / PIR foam takes place after or at the earliest just when the fiber reinforcements 10 are all impregnated with the mixture 12. In doing so, the expansion of the PUR / PIR foam is produced while maintaining a perfect specific distribution of the fibers 10 in the volume of the PUR / PIR foam block 20, so as to obtain the desired fiber density gradient. The object of the present invention is achieved by arranging fiber reinforcements parallel to each other, or in superimposed layers, each of these reinforcements having a greater or lesser density of fibers compared to the others. Thus, the fiber reinforcements intended for the peripheral zones 21, 22, or even the central zone 26, have a higher fiber density than those of the intermediate zone 23, or even the middle zones 24, 25 in the embodiment where a central zone 26 is present.

[0117] More specifically, the peripheral zones 21, 22, as well as optionally the central zone 26, have fiber densities in comparable ranges or areas, or with a high fiber density. Thus, it can be defined that the fiber density ratio for these zones 21, 22, 26 is included in the inequalities defined below:

2/3 <Tf sup. / Tf inf. £ 3/2 and Tf int. <Tf su _P. , Tf inf. : in the case of the two peripheral zones 21, 22 and of the intermediate zone 23 shown in FIG. 3;

2/3 £ Tf cen. / (Tf inf. OR Tf sup.) £ 3/2 and Tf med. <Tf inf. , Tf sup. , Tf cen. ! in the C3S of the two peripheral zones 21, 22 and of the intermediate zone 23 constituted by the central zone 26 and the two middle zones 24, 25 shown in FIG. 4.

[0118] These areas 21, 22, 26 with a high fiber density have a density of

fibers between 10% and 45% by mass of fibers relative to the local mass (considered in said zone 21, 22 or 26) of the foam block 20, preferably between 12% and 25% by mass of fibers.

[0119] In contrast, the intermediate zone 23 (in the absence of a central zone 26) and the middle zones 24, 25 (when a central zone 26 is present) have a relatively lower fiber density. In these zones 23 or 24, 25, the fiber density is between 1% and 20% by mass of fibers relative to the local mass of the foam block 20, preferably between 4% and 11% by mass of fibers per relative to the local mass in the PUR / PIR 20 foam block.

[0120] If one compares the zones 21, 22, 26 of high fiber density with the zones 23 or 24, 25 of low fiber density, the zones 21, 22, 26 of high fiber density preferably have a fiber density at least greater than that of zones 23 or 24, 25 with low fiber density, or even advantageously two to three times greater than that of areas 23 or 24, 25 with low fiber density.

[0121] In the context of the invention, the cream time of the components of the mixture 12 to form the PUR / PIR foam is known to those skilled in the art and chosen in such a way that the transport belt 11 brings the assembly together. formed from the mixture 12 of components, the blowing agent and the fibers 10 for example up to a double strip laminator, not shown in the accompanying figures, while the expansion of the foam has just started, in other words the PUR / PIR foam expansion then ends in the dual belt laminator.

In such an embodiment with a double strip laminator (DBL), a pressure system, using one or two rollers, is optionally arranged before the double strip laminator, or between the region of impregnation of the mixture on the fibers and the double strip laminator. In the case of the use of a DBL, the expansion of the volume of the foam is carried out in the laminator when the expansion volume of this foam reaches between 30% and 60% of the expansion volume of this same foam when the expansion is left free, or without any constraint. In doing so, the double belt laminator will be able to constrain the expansion of the PUR / PIR foam in its second expansion phase, when this is close or relatively close to its maximum expansion, that is to say when its expansion brings the foam close to all of the walls, forming a tunnel of rectangular or square section, of the double strip laminator. According to a different way of presenting the specific choices of the preparation according to the invention, the freezing point of the mixture of components, that is to say the moment when at least 60% of the polymerization of the mixture of components is reached, in other words 70% to 80% of the maximum volume expansion of the mixture, imperatively takes place in the double strip laminator, possibly in the second half of the length of the double strip laminator (i.e. closer to the exit of the laminator than to the entry of the latter).

[0123] Regarding the function of simultaneous distribution of the mixture 12 of

chemical components and blowing agent over the entire width L of the fiber reinforcements 10, it is here provided by a controlled liquid distributor 15, visible on FIG. 2. Such a distributor 15 comprises a supply channel 16 for the assembly formed of the mixture 12 of chemical components and at least of the swelling agent from the reservoir forming a reagent mixer, not shown in the appended figures, in which on the one hand are mixed all the chemical components and the swelling agent and on the other hand is carried out in particular the nucleation, or even the heating, of such a mixture. This liquid assembly formed of the mixture 12 of chemical components and of the blowing agent is then distributed, under pressure, in two channels 17 extending transversely to respectively end in two identical distribution plates 18, extending along the width L ( each having a length substantially equal to L / 2), comprising a plurality of nozzles 19 for the flow of said mixture 12 over the fiber reinforcements 10. These flow nozzles 19 consist of orifices of calibrated section having a determined length. The length of these flow nozzles 19 is thus determined so that the liquid leaves with an identical flow rate between all the nozzles 19 so that the impregnation of the fiber reinforcements 10 takes place at the same time, or simultaneously, on the section of width L of the fiber reinforcements 10, and that the surface mass of liquid deposited in line with each nozzle is equal. In doing so, if we consider a section of width L of the fibers 10, the latter are impregnated

concurrently so that the impregnation of the layers of fibers 10 by the mixture 12 is carried out, at all points of this section, in an identical manner, which contributes to obtaining at the outlet of the double strip laminator a block of fiber foam 20 in which the local fiber density precisely corresponds to the fiber density of each of the superimposed layers of the fiber reinforcements, at the time of gravitational casting of the mixture 12.

[0124] The controlled liquid distributor 15 shown in this FIG. 2 is a

exemplary embodiment in which two identical distribution plates 18 are used but a different design could be envisaged, insofar as the function of simultaneous liquid distribution over the cross section of the fibers 10 is achieved. Of course, the main technical feature used here lies in the different lengths of the nozzles.

flow 19, more or less long depending on the route, or route, of the liquid mixture 12 from the supply conduit 16 of the distributor 15 to the flow nozzle 19 in question.

[0125] One of the important aspects for achieving good impregnation of

10 fiber reinforcements just before the cream time te of the PUR / PIR foam lies in the choice of a specific viscosity of the liquid (consisting of the mixture 12 of chemical components and the blowing agent) to relate with the characteristics specific to the different fiber reinforcements, variable according to the fiber density. The chosen viscosity range as well as the

permeability characteristics of the fiber reinforcements must allow good penetration of the liquid into the first layers of fibers 10, to reach the following ones up to the last layer (the lower layer of fibers 10, that is to say the one located lowest in the stack fiber reinforcements), so that the impregnation time ti of the fibers 10 is achieved within the time period given by the chemical components corresponding substantially, but always less, to the cream time te. The viscosity of the mixture 12 of components is chosen, for example by heating, adding plasticizers and / or by a greater or lesser nucleation, such that the impregnation of all the fibers 10 by the mixture 12 of chemicals and of the swelling agent, over a section of width L, is obtained just before the cream time, that is to say before or just before the beginning of the expansion of the foam of

PUR / PIR.

[0126] The block of fiber-reinforced foam 20 is intended for use in a very specific environment, and must therefore guarantee specific mechanical and thermal properties. The fiber-reinforced foam block 20 obtained by the preparation according to the present invention thus conventionally forms part of a thermal insulation block 30, either in the example used in FIG. 5, in a top or primary panel 31 and / or a lower or secondary panel 32 of such an insulation block 30 of a tank 71 intended to receive an extremely cold liquid, such as LNG or LPG. Such a tank 71 can be fitted, for example, with a ground tank, a floating barge or the like (such as an FSRU “Floating Storage Regasification Unit” or a FLNG “Floating Liquefied Natural Gas”) or else a ship, such as an LNG carrier, transporting this energetic liquid between two ports.

The foam block according to the invention shown in Figure 6 comprises a plurality of anchors 40, distributed over its different faces, upper 41, and lateral 42, 43. These anchors 40 are placed so as to be flush with the surface of said faces 41, 42, 43 of the foam block, without having a foam thickness (or not significant) covering it and / or protecting it from the outside.

[0128] Figure 7 shows, in section, an embodiment of such an insert 40. This insert 40 has a plate 44 extending in a plane. This plate 44 comprises a plurality of orifices 45 which consist of a mechanical anchoring means, in other words one of the two elements making it possible to fix, when engaged with an element of the thermal insulation block (not shown in the accompanying figures), the foam block in or in the thermal insulation block of the tank. The plate 44 also comprises a plurality of identical fixing studs 46 as well as a central fixing stud 47 having larger dimensions than that of the fixing studs 46. The function of these studs 46, 47 is to fix the best possible. 'insert 40 in the block of fiber foam according to the invention. The fixing studs 46 are ideally placed

circumferentially to form a circle near the periphery or the periphery of the insert 40.

[0129] The insert 40 shown in Figure 7 is advantageously placed on the transport belt 11, the pads 45, 46 then being directed upwards and the plate 44 resting on said strip 11.

[0130] Nevertheless, one can also consider placing these inserts 40 on the upper face 41 of the block, or even on the side faces 42, 43 as can be seen on the block shown in FIG. 4. In the latter case, we can advantageously provide for at least slightly pushing the pads 45, 46 into an adjacent / contiguous mat of fibers, before it is impregnated with the polymer foam. Of course, one of these holes 45 of the anchor 40 can as such be used to form the female part of the anchor, but it is also possible to provide that the anchor requires the use of plurality of orifices 45. Furthermore, these orifices 45 consist of an anchoring solution but the invention is in no way limited to this embodiment and one or more anchors 40 of shape and mechanical characteristics can be considered. different.

Referring to Figure 8, a cutaway view of an LNG carrier 70 shows a sealed and insulating tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the vessel 71 comprises a primary waterproof barrier intended to be in contact with the LNG contained in the vessel, a secondary waterproof barrier arranged between the primary waterproof barrier and the double hull 72 of the ship, and two insulating barriers arranged respectively between the vessel. primary watertight barrier and the secondary watertight barrier and between the secondary watertight barrier and the double shell 72.

[0133] In a manner known per se, the loading / unloading pipes 73 arranged on the upper deck of the ship can be connected, by means of suitable connectors, to a maritime or port terminal for transferring an LNG cargo from or to the tank. 71.

[0134] FIG. 8 represents an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipe 76 and an onshore installation 77. The loading and unloading station 75 is a fixed off-shore installation. comprising a movable arm 74 and a tower 78 which supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the pipes of

loading / unloading 73. The movable swivel arm 74 adapts to all sizes of LNG carriers. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the onshore installation 77. The latter comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underwater pipe 76 to the loading or unloading station 75. The underwater pipe 76 allows the transfer of the liquefied gas between the loading or unloading station 75 and the shore installation 77 over a long distance, for example 5 km, which makes it possible to keep the LNG carrier 70 at a great distance from the coast during loading and unloading operations.

To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps fitted to the shore installation 77 and / or pumps fitted to the loading and unloading station are used. 75.

[0136] As stated above, the use or application of

the object of the present invention, namely in this case the block of fiber-reinforced polyurethane / polyisocyanurate foam 20, is not intended to be reduced to a tank integrated into a supporting structure but it is also intended for tanks of type A , B and C of the IGC code in force on the date of filing of the present application, but also for future versions of this code except that very substantial modifications apply to these tanks of type A, B and C , it being understood moreover that other types of tanks could, in this hypothesis of a modification of the IGC code, become possible applications for the block of fiber-reinforced PUR / PIR foam 20 according to the present invention.

[0137] In the following, part of the experiments and tests carried out by the

Applicant to enable it to appreciate the subject of the invention and its scope are presented, considering that other tests / experiments have been carried out and will be likely to be provided subsequently, if necessary / required.

A polyisocyanurate foam composition, integrating fibers in the form of mats, is used to demonstrate the invention, these fibers always appearing as long to continuous, more precisely the lengths of these fibers are exactly the same in the compositions according to the invention and those according to the state of the art. The Applicant has in particular tested the subject of the invention with so-called short fibers (as opposed to the definition given above for long to continuous fibers) or which are in the form of a fabric and the results obtained are equivalent or almost similar to those obtained with a mat of long to continuous fibers, as presented below. [0139] Thus, in order to ensure that only the combination of particular characteristics of fiber density of the fiber reinforcements with the choice of a PIR foam exhibiting in particular a particular cream time, or adapted to the characteristics of said reinforcements of fibers, no other parameter of the preparation of a PIR foam block is modified or different, between the preparations in accordance with the invention and those in accordance with the state of the art. By way of non-exhaustive examples, mention may be made of the fact that the nucleation, the amounts of blowing agents, the reaction temperatures, nature and amounts of the mixture of chemical components, casting process, distance between the casting of the mixture of components chemicals and the DBL or the device allowing free expansion, where appropriate, are strictly identical in the cases according to the invention and in the cases according to the state of the art.

Of course, it has been chosen here to illustrate the invention using a PUR foam for the sake of clarity and conciseness, but equivalent or almost similar results have been obtained with PIR foams as well. as mixtures of PUR / PIR.

Likewise, the fiber foam preparations whose results are presented below use the free expansion technique but the Applicant has shown that equivalent or almost similar results, with regard to fiber foams according to The invention and fiber foams according to the state of the art were obtained using DBL.

[0142] It is also understood that all the compositions tested below are considered to be isodensity, it being understood that this density parameter is involved in the assessment of performance in compressive strength.

[0143] For the compositions according to the state of the art, the characteristics of the fiber reinforcements and of the PUR foam are as follows:

[0144] [Tables 1]

[0145] For the compositions according to the invention, the characteristics of the fiber reinforcements and of the PUR foam are as follows:

[0146] [Tables 2]

[0147] It is noted that the cream time for the PUR foams used and

presented above is logically the same for the compositions according to the state of the art and according to the invention, because the foam used is identical, whatever the case considered.

[0148] Following the performance of the tests, certain results are presented, in a simplified manner, below to illustrate the findings of the applicant, in the case where the fiber reinforcements are in the form of at least one mat of fiberglass.

[0149] [Tables 3]

It will be noted that the first composition (with 8 layers of U809 or U801 for a block 180 mm thick) in Table 3 above consists of a composition in accordance with document FR 2882756. The results for such a composition according to document FR 2882756 are very significantly lower than those obtained with a composition according to the present invention (last composition of Table 3).

As can be seen with the results presented in the table above, on the three criteria considered to compare the fiber foams obtained, those in accordance with the invention exhibit very significantly better results than those of the fiber foams according to state of the art.

[0151] Furthermore, it should be noted that the fiber-reinforced PUR / PIR foams according to the invention do not exhibit any significant degradation of their property relating to the (very low) thermal conductivity.

[0152] [Tables 4]

[0153] Although the invention has been described in connection with several modes of

particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0154] The use of the verb “comprise”, “understand” or “include” and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0155] In the claims, any reference sign between parentheses cannot be interpreted as a limitation of the claim.

Claims

[Claim 1] Block of polyurethane / polyisocyanurate fiber foam (20) from a thermal insulation block (30) from a sealed tank and

thermally insulating, the density of the block of fiber-reinforced foam (20) is between 30 and 300 kg / m ³ , the block of

fiber-reinforced polyurethane / polyisocyanurate (20) having an average fiber density Tf of between 1% and 60% by mass of fibers (10), and having a width L of at least ten centimeters, advantageously between 10 and 500 centimeters, and a thickness (E), from the lower face of said block (20) to its upper face, of at least ten centimeters,

advantageously between 10 and 100 centimeters, the block of fibered polyurethane / polyisocyanurate foam (20) being composed of cells storing a gas, advantageously of low thermal conductivity, characterized in that:

- the foam block (20) comprises, according to its thickness E, two peripheral zones (21, 22), one called upper (21) extending from the upper face of the block (20) and the other said lower (22) extending from the lower face of the block (20), these two zones (21, 22) each representing at most 20% according to the thickness (E) of the block (20) and being separated by a so-called intermediate zone (23); and

- The peripheral zones (21, 22), upper (21) and lower (22), respectively have a fiber density Tf sup. and Tnnf. so that ! 2/3 £ (Tf over / Tf below) £ 3/2; and

- the fiber density Tnnt. of the intermediate zone (23) is lower than the densities of the peripheral zones (21, 22), ie: Tf mt. <Tf sup. and Tf int. <Tf inf ..

[Claim 2] A block of fiber-reinforced polyurethane / polyisocyanurate foam (20) according to claim 1, wherein said two areas

peripherals (21, 22) each represent at most 10% depending on the thickness

(E) of block (20).

[Claim 3] A block of fiber-reinforced polyurethane / polyisocyanurate foam (20) according to claim 1 or 2, in which the intermediate zone (23) comprises a central zone (26), surrounded by two middle zones (24, 25), representing at most 20% depending on the thickness E, preferably at most 10% depending on the thickness E, the fiber density Tf cen. of this central zone (26) being at least one and a half times greater than that of the median zones (24, 25) Tf med. , Let Tf cen. ³ 1, 5 Tf med ..

[Claim 4] A polyurethane / polyisocyanurate fiber block (20) according to Claim 3, wherein the fiber density Tf cen. of this central zone (26) is defined relative to the fiber density Tf sup. and Tf f. peripheral (21, 22), upper (21) and lower (22) zones, such that 0.5 £ Tf cen. / (Tf mf. OR Tf sup.) £ 2.

[Claim 5] Block of fiber-reinforced polyurethane / polyisocyanurate foam (20) according to one of the preceding claims, in which the density of the block of fiber-reinforced foam (20) is between 50 and 250 kg / m ³ , preferably between 90 and 210 kg / m ³ .

[Claim 6] A block of polyurethane / polyisocyanurate fiber foam (20) according to any preceding claim, wherein at least 60%, preferably at least 80%, of said cells

storing a gas, advantageously of low thermal conductivity, have an elongated or stretched shape along an axis parallel to the axis of a thickness E of the block of fiber-reinforced polyurethane / polyisocyanurate foam (20).

[Claim 7] A polyurethane / polyisocyanurate fiber block (20) according to any preceding claim, wherein the fibers consist of glass fiber or basalt fiber, preferably glass fiber.

[Claim 8] A polyurethane / polyisocyanurate fiber block (20) according to any preceding claim, wherein the fibers are long to continuous fibers.

[Claim 9] A polyurethane / polyisocyanurate fiber block (20) according to any one of the preceding claims, in which the average fiber density Tf is between 2% and 25%, preferably 6% and 20%.

[Claim 10] A block of fiber-reinforced polyurethane / polyisocyanurate foam (20) according to any one of the preceding claims, in which the lower face and / or the upper face (41), preferably the upper face (41), of said block has (s) anchors (40) able to engage with a means for engaging the thermal insulation block (30) in order to anchor the foam block to said block (30), preferably said anchors (40) being made of a material other than foam or fibers.

[Claim 11] Sealed and thermally insulating vessel (71), said vessel (71) consisting of:

- a tank integrated into a supporting structure comprising a sealed and thermally insulating tank comprising at least one sealed metal membrane composed of a plurality of metal strakes or metal plates which may include corrugations and a thermally insulating solid (30) comprising at least one barrier thermally insulating adjacent to said membrane, or

- a type A, B or C tank according to the definition given by the IGC code comprising at least one thermally insulating block (30),

characterized in that the thermally insulating mass (30) comprises a plurality of blocks of fiber-reinforced polyurethane / polyisocyanurate foam (20) according to any one of the preceding claims.

[Claim 12] A vessel (70) for the transport of a cold liquid product, the vessel comprising at least one hull (72) and a sealed and thermally insulating tank (71) according to claim 11 disposed in the hull or mounted on said hull. ship (70) when said tank (71) is of type A, B or C according to the definition given by the IGC code.

[Claim 13] A transfer system for a cold liquid product, the

system comprising a ship (70) according to the preceding claim, insulated pipes (73, 76, 79, 81) arranged so as to connect the tank (71) installed in the hull of the ship to a floating or terrestrial storage unit (77 ) and a pump for driving a flow of cold liquid product through insulated pipelines from or to the floating or onshore storage unit to or from the vessel (70).

[Claim 14] A method of loading or unloading a ship (70) according to claim 12, wherein a cold liquid product is conveyed through insulated pipelines (73, 76, 79, 81) from or to a storage unit. floating or land (77) to or from the ship (71).

[Claim 15] A method of preparing a block of polyurethane / polyisocyanurate fiber foam (20) from a thermal insulation block of a sealed and thermally insulating tank according to one of claims 1 to 10, characterized in that that it includes the steps:

a) a mixture (12) of chemical components necessary for obtaining a polyurethane / polyisocyanurate foam, said components comprising reagents for obtaining polyurethane / polyisocyanurate,

optionally at least one reaction catalyst, optionally at least one emulsifier, and at least one blowing agent,

b) impregnation, by gravitational flow of the aforesaid mixture (12) of chemical components, of a plurality of fiber reinforcements (10), said fiber reinforcements being arranged in superimposed layers and having variable fiber densities, in which the fiber reinforcements (10) extend essentially in a direction perpendicular to the direction of said gravitational flow,

c) formation and expansion of the foam

polyurethane / polyisocyanurate fiber,

in which the expansion of the fiber-reinforced polyurethane / polyisocyanurate foam is said to be by free expansion, either without the stress exerted by a volume of closed section on at least one face, preferably the upper face, or

wherein the expansion of the fiber-reinforced polyurethane / polyisocyanurate foam is physically constrained by walls of a double strip laminator, preferably is physically constrained by the walls of a double strip laminator forming a tunnel of rectangular cross section with a distance between the walls disposed laterally equal to L and a distance between the walls disposed horizontally equal to (E), thus enclosing the expanding fiber foam so as to obtain the aforesaid block of polyurethane / polyisocyanurate fiber foam (20).

[Claim 16] Process for preparing a block of foam

A polyurethane / polyisocyanurate fiber (20) according to claim 15, in which, in the case where the expansion of step c) is carried out by free expansion, at least one of the peripheral zones (21, 22), preferably The area upper (21), is independently formed and secured, after a cutout on at least the free expansion face has been made, to form said foam block (20). j