JP7689855B2 - Phenolic resin foam composite - Google Patents

Description

The present invention relates to a phenolic resin foam composite.

In recent years, the use of foamed plastic insulation materials has been increasing in various applications in order to curb energy consumption as part of measures against global warming. Among these, high performance is required for insulation materials used under conditions that require constant temperature control, either periodically or at all times, such as factory manufacturing equipment. For example, pipe covers used to keep pipelines warm must be able to be used stably at high temperatures exceeding 150°C. There are only a few products that demonstrate high insulation performance in such high-temperature environments, and phenolic resin foams, which have high heat resistance, have attracted attention as a material that can meet this requirement.

Phenolic resin foam is usually used with a surface material, but when it is processed into various shapes, it can be used without the surface material. In this case, however, it is necessary to handle it carefully so that the foam surface is not affected by contact with other hard objects.

For example, a technology has been disclosed for improving the surface strength of foams, in which a protective layer formed by impregnating a soft synthetic resin foam plate with a curable synthetic resin stock solution and curing the foam is attached to the foam. (Patent Document 1)

Japanese Utility Model Application Publication No. 49-9868

However, when such measures are used, most foamed plastic insulation materials become unusable in extreme environments, such as continuous exposure to high temperatures of 150°C or higher for long periods of time. It has been found that even with highly heat-resistant phenolic resin foam, the hardening reaction of the phenolic resin continues even after production, albeit slightly, and releases volatile components such as moisture. These volatile components can accumulate at the interface between the protective layer and the phenolic resin foam, causing swelling in the protective layer.

The present invention aims to provide a phenolic resin foam article that has improved surface brittleness and does not suffer from swelling due to volatile components that occur over time after production of the phenolic resin foam, even in harsh environments.

That is, the present invention provides the following [1] to [4].
[1]
A phenolic resin foam;
a membrane on at least a portion of the surface of the phenolic foam;
A phenolic resin foam composite comprising:
The membrane is made of a polymeric material;
the membrane has a plurality of pores;
The ratio of the total area of the holes to the surface of the membrane having the holes is 0.1% or more and 12.0% or less,
The maximum hole area of the hole is 1.0 ^mm2 or less,
A phenolic resin foam composite, wherein the film has a thickness in the range of 5 μm or more and 1000 μm or less.
[2]
2. The phenolic foam composite of claim 1, wherein the membrane is on all sides of the phenolic foam.
[3]
The phenolic resin foam composite according to [1] or [2], wherein the film is a coating film.
[4]
The density of the phenolic resin foam is 15 kg/m3 or ^more and 100 kg/ ^m3 or less,
The phenolic resin foam has a closed cell ratio of 70% or more and less than 100%,
The phenolic resin foam composite according to any one of [1] to [3], wherein the phenolic resin foam has an average bubble diameter of 5 μm or more and 200 μm or less.

The present invention provides a phenolic resin foam composite that has improved surface brittleness and does not swell over time due to volatile components after production of the phenolic resin foam, even in harsh environments.

FIG. 1 is an example of a binarized and schematic diagram of an SEM image of the surface of the phenolic resin foam composite of Example 3. FIG. 2 is a binarized and schematic diagram of an SEM image of the surface of the phenolic resin foam composite of Comparative Example 2.

The embodiment for implementing the present invention (hereinafter, sometimes referred to as the "present embodiment") will be described in detail.

The ratio of the total area of the holes on the surface of the membrane having holes in the phenolic resin foam composite of this embodiment is determined by the method described in the examples.

The maximum pore area of the phenolic resin foam composite of this embodiment is determined by the method described in the examples.

The film thickness of the phenolic resin foam composite of this embodiment is determined by the method described in the examples.

The density of the phenolic resin foam of this embodiment is determined by the method described in the examples.

The closed cell ratio of the phenolic resin foam of this embodiment is determined by the method described in the examples.

The average cell diameter of the phenolic resin foam of this embodiment is determined by the method described in the Examples.

The phenolic resin foam composite in this embodiment has a membrane on at least a portion of the surface of the phenolic resin foam. The membrane in this invention is a structure containing a polymer and has through holes that connect the membrane surface to the foam cell structure, and the holes on the membrane surface have a form specified by the description below.

In one embodiment, the pores on the membrane surface are irregular. In another embodiment, the pores on the membrane surface are a combination of regular and irregular pores. For example, in one part of the membrane surface, the pores may be regular, and in another part, the pores may be irregular.

The total area ratio of the holes on the surface of the film having the holes of the phenolic resin foam composite of this embodiment is 0.1% to 12.0%, preferably 0.3% to 10.0%, more preferably 0.5% to 8.0%. When the area ratio of the holes is 0.1% or more, the volatile components generated by the progress of the curing of the phenolic resin foam can be sufficiently dissipated through the holes. In addition, when the area ratio is 12.0% or less and the maximum hole area described later is 1.0 ^mm2 or less, the abrasion resistance can be improved.

The maximum pore area of the pores formed in the film of this embodiment is 1.0 ^mm2 or less, preferably 0.002 ^mm2 or more and 0.8 ^mm2 or less, more preferably 0.004 ^mm2 or more and 0.6 ^mm2 or less. When the maximum pore area is 1.0 ^mm2 or less, the abrasion resistance of the phenolic resin foam composite is improved, and when the maximum pore area is 0.002 ^mm2 or more, the volatile components generated by the progress of hardening of the phenolic resin foam can be sufficiently dissipated.

In this embodiment, the thickness of the film is in the range of 5 μm to 1000 μm, preferably in the range of 10 μm to 800 μm, and more preferably in the range of 15 μm to 600 μm. If the film thickness is 5 μm or more, brittleness can be improved, and if the film thickness is 1000 μm or less, there is no risk of compromising lightness.

The preferred density range of the phenolic resin foam used in this embodiment is 15 kg/m3 or ^more and 100 kg/ ^m3 or less, more preferably 20 kg/m3 or ^more and 80 kg/ ^m3 or less, and even more preferably 25 kg/ ^m3 or more and 60 kg/ ^m3 or less. If the density is 15 kg/ ^m3 or more, it has a strength that is difficult to be damaged during handling, and if it is 100 kg/ ^m3 or less, it is lightweight and therefore easy to work.

The preferred range of the closed cell ratio of the phenolic resin foam used in this embodiment is 70% or more and less than 100%, more preferably 80% or more and less than 100%, and particularly preferably 85% or more and less than 100%. If the closed cell ratio is 70% or more, the phenolic resin foam will exhibit heat insulating performance.

The preferred range of average bubble diameter of the phenolic resin foam used in this embodiment is 5 μm or more and 200 μm or less, more preferably 10 μm or more and 200 μm or less, and even more preferably 10 μm or more and 180 μm or less. If the average bubble diameter is 200 μm or less, heat conduction due to radiation is suppressed, resulting in high insulation performance, and if it is 5 μm or more, the closed cell ratio can be maintained.

The preferred thickness of the phenolic resin foam composite of this embodiment is 2 mm or more and 500 mm or less, more preferably 5 mm or more and 400 mm or less, and even more preferably 10 mm or more and 300 mm or less. If the thickness of the phenolic resin foam composite is 2 mm or more, the insulation performance is improved, and if it is 500 mm or less, the workability is improved. The thickness of the phenolic resin foam composite can be measured with a ruler, calipers, etc.

Materials for forming the membrane of the phenolic resin foam composite of this embodiment include, for example, water-based paints such as acrylic resin emulsions, urethane resin emulsions, vinyl chloride resin emulsions, and saran resin emulsions; solvent-based paints such as epoxy resin paints, acrylic resin paints, urethane resin paints, silicone resin paints, fluororesin paints, and polyester resin paints in which resin is dissolved in a solvent; and powder paints that do not contain solvents. Among these, acrylic resin emulsions and urethane emulsions are preferred because they are compatible with phenolic resin foams.

Methods for applying or attaching paint to phenolic resin foam include, for example, spray coating (also called spray coating), roll coating, curtain coating, and immersion coating (also called dip coating). Among these, spray coating and immersion coating are preferred because they can form a coating film of the desired thickness evenly on the uneven surface of the phenolic resin foam.

The phenolic resin foam composite of this embodiment can be suitably applied to, for example, plant piping that is heated by steam sterilization, compost tanks that are operated at relatively high temperatures, etc.

The phenolic resin foam composite of this embodiment can be produced, for example, by processing a single sheet of phenolic resin foam or a laminate of single sheets into any shape, such as a pipe cover shape, covering the phenolic resin foam with a mesh screen, applying a coating material for the membrane to the phenolic resin foam covered with the mesh screen, and removing the mesh screen immediately after application.

As another method for producing the phenolic resin foam composite of this embodiment without using a mesh screen, a liquid that is insoluble in the coating material for the membrane, such as a fluorine-based liquid, is mixed and dispersed in the coating material to prepare a coating material, and the coating material is then applied to the phenolic resin foam to produce the phenolic resin foam composite. Examples of liquids that are insoluble in coating materials include Opteon SF10 (manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.) and Fluorinert FC-72 (manufactured by 3M Japan Ltd.).

The preferred range of the amount of liquid insoluble in the paint to be added is, for example, 10 parts by mass or more and 120 parts by mass or less, more preferably 20 parts by mass or more and 80 parts by mass or less, per 100 parts by mass of the non-volatile content of the paint emulsion.

The phenolic resin foam composite of this embodiment has high surface strength, and the preferred range of the weight loss rate of the abrasion resistance measured by the method described below is 0% to 10%, more preferably 0% to 7%, and even more preferably 0% to 5%.

The preferred range of the weight loss rate of the volatile component release of the phenolic resin foam composite of this embodiment, measured by the method described below, is 4% to 15%, and more preferably 6% to 10%. It can be confirmed that the weight loss rate of the phenolic resin foam composite of this embodiment is greater than that of a phenolic resin foam composite having a non-porous membrane.

Details of the materials and tools used in the examples are as follows.
Surfactant: Ethylene oxide-propylene oxide block copolymer (BASF Corporation, trade name "Pluronic (registered trademark) F-127"
Solvent: normal pentane, manufactured by Kanto Chemical Co., Ltd. Fluorine solvent: product name "Opteon (registered trademark) SF10" manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.
Silicone-modified acrylic emulsion: "Polydurex B3220" manufactured by Asahi Kasei Corporation, non-volatile content 50% by mass
Acrylic emulsion: "Exceed Coat FS Clear" manufactured by Taiyo Paint Co., Ltd., non-volatile content 50% by mass
Formwork: Punched metal with nonwoven fabric on the inside, inner dimensions 300mm x 300mm x 60mm
Lid: Punched metal with nonwoven fabric on the back Mesh screen: Siding mesh sheet, manufactured by Soft99 Corporation, wire diameter 0.7 mm, mesh size 0.9 mm
Scanning electron microscope sample preparation attachment: JEOL Ltd. product name "DII-29010SCTR Smart Coater"
Scanning electron microscope (SEM): JEOL Ltd. product name "JCM-7000"
Air comparison type specific gravity meter: Tokyo Science Co., Ltd., Model 1000 Rotational viscometer: Toki Sangyo Co., Ltd., product name "R-100 type", rotor part is 3° x R-14

The properties of the phenolic resin foam and phenolic resin foam composite of this embodiment were determined by the following method using the test pieces described below.

<Area ratio of membrane pores and maximum pore area>
The test piece was cut into 5 pieces with a thickness of about 3 mm and a size of about 10 x 10 mm so as to include the film surface, and gold was deposited on the film surface with a scanning electron microscope sample preparation attachment, and then 2 locations of each sample were photographed with SEM so that the fields of view did not overlap, for a total of 10 images at a magnification of 50 times. The photographed SEM images were binarized with ImageJ (version 1.53b), and the area ratio of the lower brightness side from the rising position of the brightness distribution was calculated, and this was taken as the ratio of the total area of the holes on the surface of the film having holes. In addition, the area of the largest hole in the photographed SEM images was measured, and this was taken as the maximum hole area. The binarized and schematic diagrams of the surface SEM images of Example 3 and Comparative Example 2 are shown in Figures 1 and 2, respectively.

<Density of phenolic resin foam>
The density of the phenolic resin foam of this embodiment was determined by cutting a phenolic resin foam not including a membrane into a cube with a side length of approximately 50 mm, measuring the dimensions to the nearest 0.1 mm, and dividing the mass of the test piece measured to the nearest 0.01 g by the volume calculated from the outer dimensions. If it is difficult to calculate the volume by the above method, the density may be determined by dividing the mass by the volume obtained by, for example, submerging the foam in liquid and measuring the volume.

<Closed cell ratio of phenolic resin foam>
The closed cell ratio of the phenolic resin foam of this embodiment was calculated as follows: First, the phenolic resin foam not including the membrane and the joint was cut into a cube with a side length of approximately 25 mm. Then, the volume of the cube was measured by the standard method of using an air comparison type specific gravity meter. The volume was subtracted from the volume by the volume of the cell walls calculated from the weight and the resin density, and the value was divided by the apparent volume calculated from the outer dimensions to obtain the closed cell ratio. However, the calculation was performed assuming that the density of the phenolic resin was 1.27 g/ ^cm3 .

<Average cell diameter of phenolic resin foam>
The average cell diameter of the phenolic resin foam of this embodiment was measured as follows. Four straight lines, each 2000 μm long (actual length on the image: 10 cm), were drawn on a 50x SEM image of a test piece including a membrane cross section, without crossing the membrane cross section. The start points of the lines were placed on the cell walls. The length on the image to the last cell wall crossed by the line was divided by the number of cells crossed by the line to determine the value N. The values N of the four lines were averaged to determine the average cell diameter.

<Film thickness>
The length of the perpendicular line to the membrane surface of the membrane cross section in the SEM image used for measuring the average bubble diameter was determined, and the range from the minimum value to the maximum value of that length was defined as the membrane thickness range.

<Brittleness of phenolic resin foam composite>
Twelve cubes with sides of 25±1.5 mm were cut out from the phenolic resin foam. The entire surface of the cube was coated with a coating material using a spray gun, and the entire surface of the phenolic resin foam was dried at room temperature for 12 hours or more to obtain a test piece having a coating film on the entire surface of the phenolic resin foam. The uncoated product of Comparative Example 1 was also used as a test piece without coating with a coating material. Twenty-four oak cubes with sides of 19±08 mm and 12 test pieces dried at room temperature were placed in an oak wooden box with inner dimensions of 191 mm×197 mm×197 mm, which could be sealed so that the shavings of the test pieces would not come out of the box. The wooden box was rotated 600±3 times at a speed of 60±2 revolutions per minute. After the rotation was completed, the contents of the box were transferred to a mesh with a nominal dimension of 9.5 mm, and the small pieces were removed by sieving. Next, if a film remained on the remaining test piece, the film was removed and the weight was measured. The weight loss rate before and after the test was calculated from the weight of the phenolic resin foam before the coating film was formed and the weight of the phenolic resin foam after the coating film was removed. The brittleness of the phenolic resin foam was evaluated from the weight loss rate of the foam. The smaller the weight loss rate of the foam, the less brittle the phenolic resin foam is and the more excellent the wear resistance is.

<Volatile component release from phenolic resin foam composite>
Two rectangular parallelepipeds measuring 100±2.0 mm×100±2.0 mm×50±2.0 mm were cut out from the phenolic resin foam. The entire surface of the rectangular parallelepiped was coated with a coating material using a spray gun, and the coating material was left at room temperature for 12 hours or more to obtain a test piece having a coating film on the entire surface of the phenolic resin foam. The uncoated sample of Comparative Example 1 was used as a test piece without coating. The weight of the obtained test piece was measured.

The test specimen was then placed in an oven at 180°C, and after 16 hours, it was removed and cooled at room temperature of 23°C for 30 minutes, and the weight of the test specimen was measured. The volatile component release was evaluated from the weight loss rate of the test specimen before and after heating in an oven at 180°C.

<Blistering of phenolic resin foam composite>
In addition, the test pieces used to evaluate the volatile component release property were also checked for the presence or absence of swelling of the test pieces when heated.

The phenolic resin foam composite of this embodiment will be described in more detail below with reference to examples.

<Preparation of phenolic resin foam>
3500g of 52% by mass formaldehyde aqueous solution and 2510g of 99% by mass phenol were charged into the reactor, stirred with a propeller rotating stirrer, and the temperature inside the reactor was adjusted to 40 ° C. with a temperature controller. Next, the temperature was raised while adding 50% by mass sodium hydroxide aqueous solution, and a synthesis reaction of a phenolic resin was carried out. The viscosity of the phenolic resin reaction solution obtained by the synthesis reaction was measured using an Ostwald viscometer in a thermostatic water bath for viscosity measurement at 25 ° C. When the viscosity of the reaction solution reached 60 centistokes, the reaction solution was cooled and 500g of urea was added. Thereafter, the reaction solution was cooled to 30 ° C. and neutralized to pH 6.4 with a 50% by mass aqueous solution of paratoluenesulfonic acid monohydrate. The neutralized phenolic resin reaction solution was dehydrated at 60 ° C. The dehydrated phenolic resin was stabilized at 40 ° C. for 3 minutes. The viscosity of the phenolic resin was measured with a rotational viscometer, and was 5000 mPa · s.

2.5 parts by mass of surfactant was mixed with 100 parts by mass of dehydrated phenolic resin. 6.0 parts by mass of normal pentane was mixed with this mixture. 5 parts by mass of a mixture of xylene sulfonic acid and diethylene glycol in a mass ratio of 1:1 that had been prepared in advance was further mixed with this mixture to prepare a foamable composition. Next, 340 g of the foamable composition was placed in a mold and the lid was placed on the mold. The container was placed in an oven at 80°C and heated for 60 minutes to produce eight phenolic resin foams with nonwoven fabrics on the top and bottom surfaces. The surface layer containing the nonwoven fabric was removed from this phenolic resin foam, and test pieces of a specified size were cut out for evaluation.

Example 1
A coating material for the membrane was prepared by adding 10 parts by mass of a fluorine solvent to 100 parts by mass of a silicone-modified acrylic emulsion diluted 1.3 times and thoroughly mixing the mixture. The coating material for the membrane was applied to the entire surface of a phenolic resin foam cut to a predetermined size using a spray gun to prepare a test piece.

Example 2
Test specimens were prepared in the same manner as in Example 1, except that a mesh screen was placed over the phenolic foam during spray painting and no fluorine solvent was added.

Example 3
Test pieces were prepared in the same manner as in Example 1, except that an acrylic emulsion diluted 1.5 times was used instead of the silicone-modified acrylic emulsion diluted 1.3 times.

Example 4
Test pieces were prepared in the same manner as in Example 1, except that a mesh screen was placed over the phenolic foam during spray painting.

<Comparative Example 1>
In Example 1, the phenolic resin foam cut into a predetermined size was used as a test piece without being coated with a coating material for the membrane.

<Comparative Example 2>
Test pieces were prepared in the same manner as in Example 1, except that no fluorine solvent was added.

<Comparative Example 3>
A test piece was prepared in the same manner as in Example 1, except that the amount of the fluorine solvent was changed to 60 parts by mass.

表１中、フッ素溶剤の量は、塗料エマルションの不揮発分１００質量部に対するフッ素溶剤の質量を表す。

In Table 1, the amount of fluorine solvent indicates the mass of the fluorine solvent per 100 parts by mass of the non-volatile matter of the paint emulsion.

As can be seen from Table 1, the examples provided phenolic resin foam articles with improved surface brittleness and reduced swelling caused by volatile components that occurs over time in phenolic resin foam after production.

The present invention provides a phenolic resin foam article that has improved surface brittleness and reduced swelling caused by volatile components that occurs over time after production of the phenolic resin foam.

Claims (5)

A phenolic resin foam;
a membrane on at least a portion of the surface of the phenolic foam;
A phenolic resin foam composite comprising:
The membrane is made of a polymeric material;
the polymeric material is made of a non-volatile component of an emulsion;
the membrane has a plurality of pores;
The ratio of the total area of the holes to the surface of the membrane having the holes is 0.1% or more and 12.0% or less,
The maximum hole area of the hole is 1.0 ^mm2 or less,
A phenolic resin foam composite, wherein the film has a thickness in the range of 5 μm or more and 1000 μm or less. The phenolic resin foam composite according to claim 1 , wherein the emulsion is one or more emulsions selected from the group consisting of an acrylic resin emulsion, a urethane emulsion, a vinyl chloride resin emulsion, and a saran resin emulsion. The phenolic foam composite of claim 1 or 2 , wherein the membrane is on all sides of the phenolic foam. The phenolic resin foam composite according to claim 1 , wherein the film is a coating film. The density of the phenolic resin foam is 15 kg/m3 or ^more and 100 kg/ ^m3 or less,
The phenolic resin foam has a closed cell ratio of 70% or more and less than 100%,
The phenolic resin foam composite according to any one of claims 1 to 4 , wherein the phenolic resin foam has an average bubble diameter of 5 µm or more and 200 µm or less.