Heat insulating material

Abstract

To provide a heat insulating material that can bond a core material and a gas barrier layer without requiring complicated processes such as an adhesive layer or corona treatment, can suppress gas leakage even under high temperature and high humidity conditions, and exhibits stable heat insulating performance for a long period of time.SOLUTION: A heat insulating material is configured such that on both surfaces of a core material made of synthetic resin foam, a surface material is laminated. The surface material has at least a paper base material and a gas barrier layer. The gas barrier layer contains a polyvinyl alcohol resin or a polyvinylidene chloride resin, and is in contact with the synthetic resin foam. A rate of change in a thermal conductivity of the heat insulating material is 8% or less after three months of storage under a standard temperature condition of Class 3 and a standard humidity condition of Class 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat insulating material that can suppress deterioration of its heat insulating performance over time and exhibit stable heat insulating performance over a long period of time. [Background technology]

[0002] BACKGROUND ART Heat insulating boards, which are made by laminating facing materials on both sides of a core material made of synthetic resin foam, are used as heat insulating materials for walls, floors, and roofs of detached houses and the like. An insulation board with a rigid polyurethane foam core is formed by dispensing a mixture of polyol and polyisocyanate components onto a facing material, then laminating the facing material on top and allowing the sandwiched material to react and harden. The foam's bubbles trap insulating gases other than air (carbon dioxide produced by reaction with a blowing agent or water), providing insulation. However, the insulating gases within the bubbles are gradually released through the facing material and replaced with air, resulting in a loss of insulation performance. Therefore, to maintain long-term insulation performance, it is necessary to prevent the insulating gas from leaking out. Therefore, facing materials containing metal foils, such as aluminum foil, which have high gas barrier properties, have traditionally been used. In addition, additional layers with functions such as heat insulation may be laminated on the opposite side of the facing material from the core material. However, as in the conventional heat insulating material shown in Fig. 4, the metal foil 60 has poor adhesion to the rigid polyurethane foam and other layers (paper substrate 40), so it was necessary to provide an adhesive layer 50 (a laminated resin layer such as polyethylene) between the metal foil 60 and the polyurethane foam (core material 10). Also, it was sometimes necessary to provide an adhesive layer on the face material or to subject the adhesive layer to surface treatment such as corona treatment, which made the manufacturing process for the face material complicated. It is also known to use a material having an inorganic thin film containing at least a metal on a resin substrate as a face material with gas barrier properties (Patent Document 1). The foam insulation material described in Patent Document 1 has a resin substrate between the inorganic thin film, which is the gas barrier layer of the face material, and the foam layer, so there is a risk of insulating gas leaking through the resin substrate layer. In addition, surface treatment such as corona treatment may be required to improve adhesion between the resin substrate and the foam layer, making the manufacturing process complicated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-84395 Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, an object of the present invention is to provide a heat insulating material that can bond a core material and a gas barrier layer without requiring complicated processes such as laminating adhesive layers or corona treatment, that suppresses gas leakage, and that exhibits stable heat insulating performance over a long period of time. [Means for solving the problem]

[0005] A first aspect of the present invention is an insulating material comprising a core material made of synthetic resin foam and face materials laminated on both sides of the core material, wherein the face material has at least a paper base material and a gas barrier layer, the gas barrier layer contains a polyvinyl alcohol-based resin or a polyvinylidene chloride-based resin and is in contact with the face of the synthetic resin foam, and wherein the rate of change in thermal conductivity is 8% or less after 3 months of storage under standard temperature condition class 3 and standard humidity condition class 3. A second aspect of the present invention is the heat insulating material according to the first aspect, characterized in that the gas barrier layer in contact with the surface of the synthetic resin foam has a wet tension of 35 mN / m or more and 72 mN / m or less according to JIS K6768. A third aspect of the present invention is the heat insulating material according to the first or second aspect, wherein the gas barrier layer contains an inorganic pigment. A fourth aspect of the present invention is the heat insulating material according to the first or second aspect, wherein the gas barrier layer contains kaolin. [Effects of the Invention]

[0006] The present invention can provide a heat insulating material that has good adhesion between the core material and the gas barrier layer without the need for an adhesive layer, and that exhibits stable heat insulating performance over a long period of time. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a laminated structure of a heat insulating material according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing a laminated structure of a heat insulating material according to another embodiment of the present invention. [Figure 3] 1 is an apparatus for manufacturing the insulating material of the present invention. [Figure 4] This is a cross-sectional view showing the laminated structure of a conventional heat insulating material, which uses a surface material containing metal foil such as aluminum foil, which has high gas barrier properties. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following embodiments of the present invention are examples of the configuration of the present invention, and are described in terms of sections to facilitate understanding of the various configurations of the present invention. Each section does not limit the technical scope of the present invention, and while taking into consideration the best mode for carrying out the invention, some of the components of each section may be replaced or deleted, or other components may be added, and these may also be included in the technical scope of the present invention.

[0009] (Embodiment 1) As shown in Fig. 1, one embodiment of the heat insulating material of the present invention is a heat insulating material in which facing materials 20 are laminated on both sides of a core material 10 made of synthetic resin foam. The facing material 20 has at least a paper substrate 40 and a gas barrier layer 30, and the gas barrier layer 30 contacts the faces of the core material 10.

[0010] Examples of the synthetic resin foam include rigid polyurethane foam, polyisocyanurate foam, etc. The thickness of the synthetic resin foam is preferably in the range of 10 to 100 mm, and the density is preferably 25 to 50 kg / m 3 It is better to have something like this.

[0011] The face material 20 is formed by laminating at least the gas barrier layer 30 and the paper substrate 40 in this order on the core material 10 (see FIG. 1). The gas barrier layer 30 of the present invention uses a resin instead of the metal foil, particularly aluminum foil, that is used in conventional gas barrier layers. From the viewpoint of gas barrier properties, the resin can be a polyvinyl alcohol-based resin or a polyvinylidene chloride-based resin. The polyvinyl alcohol-based resin may include a fully saponified polyvinyl alcohol, a partially saponified polyvinyl alcohol, or the like.

[0012] Furthermore, it is preferable to incorporate an inorganic pigment into the gas barrier layer in order to improve the gas barrier properties. As the inorganic pigment used in the gas barrier layer, flat inorganic pigments such as kaolin, talc, clay, and mica can be used alone or in combination of two or more. Of these, kaolin and mica are more preferred. When an inorganic pigment is contained in a gas barrier layer, gases such as oxygen pass through by bypassing the pigment, and therefore, a gas barrier layer made of a resin composition containing a pigment has superior moisture resistance and heat resistance in a high-humidity atmosphere compared to a gas barrier layer made of a resin composition that does not contain a pigment.

[0013] In addition to the resins and inorganic pigments described above, the gas barrier layer may contain various commonly used auxiliary agents such as crosslinking agents, surfactants, dispersants, thickeners, water retention agents, antifoaming agents, water-resistant agents, dyes, and fluorescent dyes.

[0014] The oxygen permeability of the gas barrier layer is 10 cc / m as measured in accordance with JIS K 7126. 2 ·24hr·atm or less is preferable.

[0015] By providing a paper substrate as the facing material of the present invention, it is possible to prevent warping as a heat insulating material and increase rigidity. The paper substrate is a sheet mainly made of pulp, and an example of this is commercially available kraft paper.

[0016] The basis weight of the paper base material of the present invention is 30 g / m 2 ~600g / m 2 The density of the paper base material of the present invention is about 1.0 g / cm 3 The range (lower limit) of density is not particularly limited as long as it is within a range that is technically feasible, but is usually 0.2 g / cm 3 or more, 0.4 g / cm 3 More than 0.9 g / cm is preferable. 3 The following is preferred:

[0017] (Embodiment 2) In another embodiment of the heat insulating material of the present invention, a facing material has a layer laminated on the side opposite the core material of a paper substrate that not only has moisture resistance and heat resistance but also has a function such as heat insulation. For example, a synthetic resin film, paper, metal foil, etc. may be laminated alone or in combination. In this embodiment of the heat insulating material, the gas barrier layer also contacts the surface of the core material. 2, for example, the gas barrier layer 30 contacts the surface of the core material 10, and in addition to the gas barrier layer 30 and the paper base material 40, a heat-shielding metal foil 60 is laminated. A synthetic resin film 50 is laminated between the metal foil 60 and the paper base material 40 so that they are in close contact with each other. In addition, to protect the metal foil 60 from the outside, a synthetic resin film 50 is laminated on the other surface of the metal foil 60. In other words, five layers are laminated in this order on the side of the face material 20 opposite the core material 10: the gas barrier layer 30, the paper base material 40, the synthetic resin film 50, the metal foil 60, and the synthetic resin film 50.

[0018] (Method of manufacturing surface materials and heat insulating materials) First, a face material is manufactured. The manufacturing method of the face material is not particularly limited. For example, a coating liquid may be prepared by mixing a solvent such as water or an organic solvent with a polyvinyl alcohol-based resin or polyvinylidene chloride-based resin constituting the gas barrier layer, an inorganic pigment, etc., and then coating and drying the coating liquid to form the gas barrier layer. Furthermore, the face material thus obtained may further have another layer having a function such as heat insulation laminated on the side of the paper substrate opposite the gas barrier layer. In this case, the lamination may be carried out by various conventionally known methods. Furthermore, another layer may be laminated between the paper substrate and the gas barrier layer, as long as the effect of the present invention is not impaired. The present invention provides excellent adhesion between the gas barrier layer and the core material without the need for an adhesive layer, thereby eliminating the need for complicated processes such as providing an adhesive layer on the face material or subjecting the adhesive layer to surface treatment such as corona treatment.

[0019] Next, using a continuous manufacturing device such as that shown in Figure 3, a urethane resin mixture of a polyol component and a polyisocyanate component is applied to each face material, and similar face materials are layered on top of each other while foaming and curing.The material is then molded to the desired thickness on a double conveyor, foaming is completed in a curing oven, and the material is side-cut and then cross-cut to produce an insulating material that is a rigid polyurethane foam with face materials layered on both the front and back sides, as shown in Figure 1 or Figure 2.

[0020] (wetting tension) The adhesion of the gas barrier layer to the core material is evaluated by measuring the wetting tension of the gas barrier layer in a test solution according to JIS K6768. The gas barrier layer to be adhered has a wet tension of 35 mN / m or more. The range (upper limit) of the wet tension is not particularly limited as long as it is within a technically feasible range, but is usually 72 mN / m or less.

[0021] (rate of change in thermal conductivity) The insulating gas contained in the synthetic resin foam loses some of its insulating performance because it is released to the outside and replaced with air. Therefore, the present invention determines the maintenance of insulating performance based on the rate of change in thermal conductivity, which is related to insulating performance. In the present invention, it is calculated by the following formula 1. Rate of change of thermal conductivity λ = (λ over time - λ initial value) / λ initial value (Equation 1) A material that keeps the rate of change in thermal conductivity λ low is evaluated as having good thermal insulation performance. The thermal insulation material of the present invention keeps the rate of change in thermal conductivity to 8% or less after three months of storage under standard temperature and humidity conditions of Class 3, as measured according to the "Rate of change in thermal conductivity" described below.

[0022] The method for producing the heat insulating material of the present invention is carried out, for example, by a continuous production apparatus configured as an inverse type as shown in Fig. 3. The method is not limited to this inverse type, and any method that can continuously produce heat insulating material can be adopted. [Example]

[0023] EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0024] [Production of surface materials and heat insulating materials] First, face materials of Examples 1-4 and Comparative Examples 1-5 were produced by laminating the materials in the configurations shown in Table 1. Table 2 shows the evaluation of the ease of production of the face materials. Next, using a continuous manufacturing apparatus as shown in FIG. 3, the heat insulating materials of Examples 5-8 and Comparative Examples 6-10 each having a thickness of 30 mm were manufactured by the above-mentioned method for manufacturing a heat insulating material. The heat insulating materials corresponding to the facing materials of Examples 1-4 and Comparative Examples 1-5 are Examples 5-8 and Comparative Examples 6-10, respectively.

[0025] The compounds used in the following examples and comparative examples are as follows. PVA: Polyvinyl alcohol resin (manufactured by Kuraray Co., Ltd., product name "Kuraray Poval") PVDC: Polyvinylidene chloride resin (manufactured by Asahi Kasei Corporation, polyvinylidene chloride resin film, product name "Saran Wrap (registered trademark)") PE: Polyethylene resin (manufactured by Tosoh Corporation, product name "Petrothene", specific gravity 0.94) EVOH: Ethylene vinyl alcohol copolymer resin (manufactured by Mitsubishi Chemical Corporation, product name "Soarnol", EVOH 71 mol%, ethylene 29 mol%) In Examples 1 and 2, the gas barrier layer contains kaolin as an inorganic pigment.

[0026] [Table 1]

[0027] [Measurement of oxygen permeability of gas barrier layer (gas barrier properties)] Based on JIS K 7126, the oxygen permeability of the gas barrier layers listed in Table 1 was measured using an oxygen permeability measuring device "OX-TRAN2 / 21" manufactured by MOCON under conditions of 23°C and 0% RH (dry conditions). The unit is cc / m. 2 ·24hrs·atm. In the case of Examples 1 to 4, the values were measured for a surface material in which a gas barrier layer was formed by applying a coating liquid containing the components listed in Table 1 onto a paper substrate and drying it. Since the paper substrate has only a minor effect on the oxygen permeability, these values are considered to be the oxygen permeability of the gas barrier layer.

[0028] [Measurement of wetting tension of layer adhering to rigid polyurethane foam] A mixture for wetting tension testing (Wako Pure Chemical Industries, Ltd., mixture for wetting tension testing) was spread on the test layer, and the test was carried out as described in JIS K 6768 to measure the wetting tension. The adhesion to rigid polyurethane foam was evaluated as follows, and the results are shown in Table 2. Regarding adhesion to rigid polyurethane foam, if the wetting tension is 35 mN / m or more, it is rated as "pass". If it is less than 30 mN / m, adhesion between the rigid polyurethane foam and the facing material cannot be obtained. ○:35mN / m or more △: 30mN / m or more and 35mN / m or less ×: Less than 30 mN / m

[0029] [Ease of manufacturing surface materials] The evaluation was as follows: 〇: No adhesive layer is required between the gas barrier layer and the core material (urethane foam) and no corona treatment is required △: An adhesive layer is required between the gas barrier layer and the core material (urethane foam) (no corona treatment) ×: An adhesive layer is required between the gas barrier layer and the core material (urethane foam) (corona treatment required)

[0030] [Table 2]

[0031] [Rate of change in thermal conductivity] The obtained insulating material was cut into a size of 200 mm in length and 200 mm in width and stored under standard temperature condition 3 and standard humidity condition 3. One day after production, the initial value was measured using the heat flow meter method specified in JIS A-1412 using an Auto λ (HC-074) manufactured by Eiko Seiki Co., Ltd. under an environment with an average temperature of 23°C. After storing for 3 months under the same conditions (room temperature conditions), the value measured was taken as the λ value over time (room temperature). After storing in an oven at 70°C (high temperature condition) for two months, the value measured was taken as the λ value over time (high temperature). After storing for two weeks in a thermo-hygrostat controlled at 35°C and 75% RH (high humidity conditions), the value measured was taken as the λ value over time (high humidity). The rate of change in thermal conductivity λ calculated by the above formula 1 was calculated in Examples and The heat insulating performance of the comparative example was evaluated.

[0032] The smaller the rate of change of thermal conductivity λ (at room temperature), the better; if it exceeds 8.0%, the heat insulating performance cannot be maintained during long-term use. ○: 3.5% or less △: More than 3.5% but less than 8.0% ×: More than 8.0% The smaller the rate of change of thermal conductivity λ (at high temperatures), the better; if it exceeds 8.0%, the heat insulating performance cannot be maintained during long-term use. ○: 3.0% or less △: More than 3.0% but less than 8.0% ×: More than 8.0% The smaller the rate of change of thermal conductivity λ (high humidity), the better; if it exceeds 12%, the heat insulating performance cannot be maintained during long-term use. 〇: 12% or less △: More than 12% but less than 15% ×: More than 15%

[0033] [Table 3]

[0034] The heat insulating material of the present invention does not use metal foil and yet provides a heat insulating effect equal to or greater than that of heat insulating materials containing metal foil. Furthermore, since it can maintain excellent thermal conductivity not only at room temperature but also under high-temperature and high-humidity conditions, it can be used in harsh environments such as roofs, which has the advantage of broadening the range of uses for heat insulating materials. [Explanation of symbols]

[0035] 10 Core material, synthetic resin foam 20 Surface material 30 Gas barrier layer 40 Paper base material 50 Adhesive layer, synthetic resin film 60 Metal Foil

Claims

1. A heat insulating material in which face materials are laminated on both sides of a core material made of synthetic resin foam, the facing material has at least a paper substrate and a gas barrier layer, the gas barrier layer contains a polyvinyl alcohol-based resin or a polyvinylidene chloride-based resin and is in contact with a surface of the synthetic resin foam; A heat insulating material characterized in that the rate of change in thermal conductivity is 8% or less after storage for three months under conditions of standard temperature condition class 3 and standard humidity condition class 3.

2. 2. The heat insulating material according to claim 1, wherein the gas barrier layer has a wet tension of 35 mN / m or more and 72 mN / m or less in accordance with JIS K6768 standard, the wet tension being in contact with the surface of the synthetic resin foam.

3. 3. The heat insulating material according to claim 1, wherein the gas barrier layer contains an inorganic pigment.

4. 3. The heat insulating material according to claim 1, wherein the gas barrier layer contains kaolin.

Images