JP5569177B2 - Fine metal hydroxide particles and method for producing the same - Google Patents

Description

  The present invention relates to fine metal hydroxide particles having excellent heat resistance and a method for producing the same.

Conventionally, in electrical and electronic equipment parts, it has been required to impart flame retardancy to ensure safety against fire.
Examples of the method for imparting flame retardancy include a method using a flame retardant resin, and halogen-containing resins such as brominated epoxy resins are generally used. Also, flame retardant fillers are often used.

Examples of flame retardant fillers include metal hydroxide particles such as aluminum hydroxide (gibbsite type, Al ₂ O ₃ .3H ₂ O), magnesium hydroxide, and particularly aluminum hydroxide contains abundant structural water and is flame retardant. In many cases, it is used for reasons such as excellent properties, acid resistance and alkali resistance, and cost advantages.

As a flame retardant property of metal hydroxides such as aluminum hydroxide and magnesium hydroxide, it is known that dehydration starts from the dehydration start temperature (aluminum hydroxide (gibbsite) is about 200 ° C, magnesium hydroxide is about 340 ° C). It has been. Further, it is known that aluminum hydroxide (gibbsite) is partially dehydrated at a temperature as high as about 50 ° C. and transferred to monohydrate boehmite (Al ₂ O ₃ .H ₂ O). However, the above dehydration may reduce the yield and physical properties of molded products using metal hydroxide particles.

For example, since the environmental temperature at the time of soldering on an electronic substrate is about 230 ° C., aluminum hydroxide may be dehydrated and yield may be reduced. Therefore, the metal hydroxide particles to be used are required not only to have flame resistance but also to not reduce the heat resistance of the molded product.
In Patent Document 1, heat resistance and flame resistance are obtained by blending a specific aluminum hydroxide having a BET non-surface area of 1.0 m ² / g and a contained Na concentration of 0.1% by weight or less in terms of Na ₂ O. The manufacturing method of the laminated board which combines these is proposed. In Patent Document 2, heat-resistant surface of the epoxy resin for encapsulating a semiconductor, the content of Na 2 _O contained in the aluminum hydroxide is usually 0.3 wt% or less, preferably 0.1 wt% It is disclosed that: Patent Document 3 discloses a method for producing aluminum hydroxide with a small amount of fixed sodium.

  On the other hand, due to the recent high integration and densification of electrical and electronic equipment parts, the demand for thinner molded products such as laminates, wiring boards, and semiconductor devices using flame retardant fillers has increased, and they are included in flame retardant fillers. Coarse particles are a problem. For example, if a filler larger than the thickness of the resin layer applied on the glass cloth in the coating process is mixed in the laminate, the filler will pop out of the resin layer during press molding, causing circuit disconnection, poor appearance, etc. There have been concerns about deterioration of laser processability and deterioration of insulation.

JP 2003-246867 A JP-A-11-228792 JP-A-8-325011

  Therefore, an object of the present invention is to provide metal hydroxide particles excluding coarse particles that retain heat resistance and flame retardancy and can cope with thinning of molded products, and a method for producing the same.

  This invention is made | formed in view of the situation which concerns, The present inventors earnestly researched about the problem that the coarse particle in a filler jumps out of a resin layer about the filler which a laminated board resin layer contains. As a result, the present inventors, for example, metal hydroxide particles such as aluminum hydroxide particles, although the heat resistance is reduced by atomization, if the metal hydroxide particles satisfy specific requirements, heat resistance And it discovered that a flame retardance was hold | maintained and completed this invention.

According to the present invention, the following metal hydroxide particles and the like are provided.
1. Metal hydroxide particles having a maximum particle size of 10 μm or less and a surface sodium concentration of 0.0018% by mass or less in terms of Na ₂ O.
2. 2. The metal hydroxide particles according to 1, having an average particle size of 2.5 to 3.5 μm.
3. Classifying the metal hydroxide particle group into a metal hydroxide particle group having a maximum particle size of 10 μm or less and a metal hydroxide particle group having a maximum particle size of more than 10 μm;
The metal hydroxide particle group having a maximum particle size of more than 10 μm is pulverized to have a maximum particle size of 10 μm or less, the classified maximum particle size is 10 μm or less, and the pulverized maximum particle size is 3. The metal hydroxide particle according to 1 or 2 obtained by mixing a metal hydroxide particle group of 10 μm or less.
4). The metal hydroxide particles according to any one of 1 to 3, which are aluminum hydroxide particles.
5. Classifying the metal hydroxide particle group into a metal hydroxide particle group having a maximum particle size of 10 μm or less and a metal hydroxide particle particle group having a maximum particle size of more than 10 μm;
The metal hydroxide particles having a maximum particle size of more than 10 μm are pulverized to have a maximum particle size of 10 μm or less,
A method for producing metal hydroxide particles, prepared by mixing the classified metal hydroxide particles having a maximum particle size of 10 μm or less and the pulverized metal hydroxide particles having a maximum particle size of 10 μm or less.
6. A laminated board obtained by impregnating a glass cloth with a resin composition containing the metal hydroxide particles according to any one of 6.1 to 4 or the metal hydroxide particles obtained by the production method according to 5.
7). A laminate that is a laminate of a resin layer and a glass cloth,
The resin layer includes a filler;
The filler is classified into a particle group having a maximum particle size of 90% or less of the thickness of the resin layer, and a particle group having a maximum particle size of more than 90% of the thickness of the resin layer, and the maximum particle size is A particle group that is more than 90% of the thickness of the resin layer is pulverized so that the maximum particle diameter is 90% or less of the thickness of the resin layer, and the particle group obtained by pulverization and the maximum particle diameter is equal to the thickness of the resin layer. A laminated board which is a filler obtained by mixing a particle group of 90% or less.
8). The laminate according to 7, wherein the filler is aluminum hydroxide particles.
9. Laminate according to 8 surface sodium concentration of the aluminum hydroxide particles is not more than 0.0018 wt% in terms of Na ₂ O.
10. The laminated board of 8 or 9 whose average particle diameter of the said aluminum hydroxide particle is 2.5-3.5 micrometers.
11. The laminated board in any one of 8-10 whose maximum particle diameter of the said aluminum hydroxide particle is 10 micrometers or less.

  ADVANTAGE OF THE INVENTION According to this invention, the metal hydroxide particle | grains except the coarse particle which hold | maintains heat resistance and a flame retardance and can respond to thickness reduction of a molded article can be provided.

The metal hydroxide particles of the present invention have a maximum particle size of 10 μm or less and a surface sodium concentration of 0.0018% by mass or less in terms of Na ₂ O.
Examples of the metal hydroxide particles include aluminum hydroxide particles and magnesium hydroxide particles, and aluminum hydroxide particles are preferable from the viewpoint of flame retardancy and chemical resistance.

The maximum particle size of the metal hydroxide particles is 10 μm or less, preferably 9 μm or less.
When metal hydroxide particles having a maximum particle size of more than 10 μm are used for the manufacture of molded products such as thin laminates, wiring boards, and semiconductor devices with a resin layer thickness of about 10 μm, the metal hydroxide particles are used during press molding. Pops out of the resin layer, causing circuit disconnection, poor appearance, and the like, and may cause deterioration of laser processability and insulation.
The maximum particle size can be measured by a laser diffraction scattering method, an ultrasonic attenuation method, a flow imaging method, or the like. The maximum particle size of the present invention is a value obtained by measurement by a laser diffraction scattering method.

  The lower limit of the maximum particle size of the metal hydroxide particles is not particularly limited. However, since the viscosity of the resin composition containing the metal hydroxide particles is increased by decreasing the maximum particle size, the maximum particle size of the metal hydroxide particles is, for example, 5 μm or more from the viewpoint of workability. .

The surface sodium concentration of the metal oxide particles of the present invention is 0.0018% by mass or less, preferably 0.0014% by mass or less, more preferably 0.0012% by mass or less in terms of Na ₂ O.
For example, the transition accompanied by dehydration of aluminum hydroxide from the gibbsite type to boehmite is likely to occur in an alkaline atmosphere. Therefore, the heat resistance can be improved by reducing the content of alkali Na ₂ O as an impurity. Therefore, particularly when the metal oxide particles are aluminum hydroxide particles, the surface sodium concentration of the aluminum hydroxide particles is 0.0018% by mass or less in terms of Na ₂ O, whereby boehmite formation is suppressed, and the composition The heat resistance of can be improved.
The method for measuring the surface sodium concentration includes ion chromatography, atomic absorption spectrophotometry, inductively coupled plasma emission spectroscopic analysis, etc. The surface sodium concentration of the present invention is measured by atomic absorption photometry (JIS-K010248). The value obtained.

The average particle diameter D50 of the metal hydroxide particles is preferably 2.5 to 3.5 μm, more preferably 2.8 to 3.2 μm.
When the average particle diameter of the metal hydroxide particles is less than 2.5 μm, the specific surface area increases, and accordingly, the surface sodium concentration increases, which may cause a decrease in heat resistance. Moreover, there exists a possibility that the viscosity of a resin composition may become high and workability | operativity may fall. On the other hand, when the average particle size is more than 3.5 μm, it may be difficult to make the maximum particle size a target particle size.
In addition, the said average particle diameter is a particle diameter obtained by the measuring method similar to the said maximum particle diameter, Comprising: A cumulative frequency 50% particle diameter is pointed out.

The metal hydroxide particles of the present invention can be prepared easily and with a high yield by the following steps (1) to (3).
(1) The metal hydroxide particle group is classified into a metal hydroxide particle group having a maximum particle size of 10 μm or less and a metal hydroxide particle group having a maximum particle size exceeding 10 μm.
(2) A metal hydroxide particle group having a maximum particle size of more than 10 μm is pulverized so that the maximum particle size is 10 μm or less.
(3) Mixing the metal hydroxide particle group having a maximum particle size of 10 μm or less classified in the step (1) and the metal hydroxide particle group having a maximum particle size of 10 μm or less pulverized in the step (2) To do.

In the step (1), by using a metal hydroxide particle group in which the surface sodium concentration of the metal hydroxide particle group before classification is 0.0018% by mass or less in terms of Na ₂ O, the maximum is obtained after classification. It can also be produced by selecting only metal hydroxide particles having a particle size of 10 μm or less. However, in the case of only classification, there is a disadvantage that the yield is low.
Further, metal hydroxide particles having a maximum particle size of 10 μm or less can be obtained with high yield only by pulverization in step (2) without performing classification in step (1). The specific surface area of the oxide particles is greatly increased, and the concentration of the surface Na ₂ O component is increased accordingly, which may reduce the heat resistance.

In the method for producing metal hydroxide particles of the present invention, the surface sodium concentration of the metal hydroxide particle group before classification in the step (1) is preferably 0.0018% by mass or less in terms of Na ₂ O, The content is more preferably 0.0014% by mass or less, and further preferably 0.0012% by mass or less.
The means is not particularly limited as long as it can reduce the possibility of contamination and there is no problem with the connection between the classifier and the pulverizer. Examples of the classification means include an airflow classifier and a wet centrifugal classifier. Examples thereof include an airflow pulverizer and a mechanical pulverizer.

  Since the metal hydroxide particles of the present invention have both flame retardancy and heat resistance, they are suitable as flame retardant fillers contained in resin compositions that are raw materials for molded products such as laminates, wiring boards, and semiconductor devices. Can be used.

  Examples of the resin component of the resin composition containing metal hydroxide particles include an epoxy resin, a polyimide resin, a triazine resin, a phenol resin, and the like. From the balance of characteristics such as heat resistance and hygroscopicity and cost, an epoxy resin is preferable. Resin.

  There is no restriction | limiting in particular as said epoxy resin, What is generally used for a laminated board can be used, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolak type epoxy resin, cresol A novolak type epoxy resin, a bisphenol A novolak type epoxy resin, etc. are mentioned, These 1 type (s) or 2 or more types can be used together. Among the above epoxy resins, bisphenol F type epoxy resin and bisphenol A novolak type epoxy resin are preferable from the viewpoint of heat resistance.

The resin composition may further contain a curing agent.
The curing agent is not particularly limited as long as it does not affect the heat resistance and flame retardancy. For example, an amine compound, a phenol compound, an acid anhydride compound, etc. are mentioned as a hardening | curing agent when using it for an epoxy resin as a resin component.
Although the addition amount of a hardening | curing agent is not restrict | limited in particular, It is preferable to use 0.1-150 mass parts with respect to 100 mass parts of resin components.

Further, the resin composition may contain a curing accelerator, an oligomer, an adhesive, a UV shielding agent, a flame retardant aid and the like, if necessary. Examples of the curing accelerator include imidazole and the like, oligomers that are filler surface agents, adhesives such as ethoxysilane, UV shielding agents such as pirarizone, and flame retardant aids such as zinc molybdate.
The curing accelerator or the like is not particularly limited as long as it does not interfere with heat resistance and flame retardancy.

Since the resin composition using the metal hydroxide particles of the present invention is excellent in heat resistance and flame retardancy, it can be particularly suitably used as a resin layer material of a laminate which is a laminate of a resin layer and a glass cloth. .
The said glass cloth is what is generally used for a laminated board, What is necessary is just to select the thing according to the thickness of the laminated board.

The filler (metal hydroxide particles of the present invention) contained in the resin layer of the laminate is a particle having a maximum particle size of 90% or less of the thickness of the resin layer, and a maximum particle size of 90% of the thickness of the resin layer. Particles with a maximum particle size exceeding 90% of the thickness of the resin layer are pulverized so that the maximum particle size is 90% or less of the thickness of the resin layer. It is a filler formed by mixing particles having a particle size of 90% or less of the thickness of the resin layer.
The classification and pulverization methods are as described above.

  In addition, a metal foil is generally used for the laminated plate, but in the laminated plate of the present invention, it is preferable to use a copper foil because it is inexpensive. As copper foil, what is generally used of a laminated board is used, What is necessary is just to select what according to the thickness of the laminated board.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples and comparative examples.

Example 1
[Production of aluminum hydroxide particles A]
Water, which is a raw material, from the inlet of a forced vortex classifier (TC-15 manufactured by Nisshin Engineering Co., Ltd.) using a quantitative supply device (Nisshin Engineering Co., Ltd., Feed Comm-M-200F type) Aluminum oxide E (HP-360 manufactured by Showa Denko KK) was supplied and classified into a particle group having a maximum particle size of 10 μm or less and a particle group having a maximum particle size of more than 10 μm, and each was separately collected with a cyclone.

Only the classified particle group having a maximum particle size of more than 10 μm is supplied to an air flow type pulverizer (Nisshin Engineering Co., Ltd., SJ-500) through a double damper through a double damper, and pulverized to a maximum particle size of 10 μm or less. The particles were classified by a forced vortex classifier to prepare a particle group having a maximum particle size of 10 μm or less.
The obtained particle group having a maximum particle size of 10 μm or less was mixed with the above-described particle group having a maximum particle size of 10 μm or less obtained only by classification to obtain aluminum hydroxide particles A.
The forced vortex classifier TC-15 classifies particles based on the balance between the centrifugal force acting on the particles and the air flow, and the airflow type pulverizer SJ-500 performs pulverization by collision of particles injected at high pressure. Is what you do.

The obtained aluminum hydroxide particles A and the starting material aluminum hydroxide E were evaluated.
As a result, the maximum particle size of the aluminum hydroxide particles A was 9.25 μm, the average particle size was 2.934 μm, the surface sodium concentration (Na ₂ O concentration) was 0.0011% by mass, and the 1% weight reduction temperature was 254.5. The yield was 80.5%.
Aluminum hydroxide E had a maximum particle size of 11 μm, an average particle size of 3.123 μm, a surface sodium concentration (Na ₂ O concentration) of 0.0011% by mass, and a 1% weight loss temperature of 251.7 ° C.

The evaluation method of aluminum hydroxide particles is as follows.
[Maximum particle size and average particle size]
The maximum particle size and the average particle size were measured using a laser diffraction scattering method (Microtrac MT3300EX-II, manufactured by Nikkiso). The measurement sample was prepared by adding aluminum hydroxide particles to a dispersion (dispersion solvent: water, dispersant: sodium hexametaphosphate (0.2 wt%)) and ultrasonically dispersing (80 W, 5 minutes). The solvent refractive index was 1.333 and the particle refractive index was 1.57.
[Na ₂ O equivalent surface sodium concentration (mass%)]
5 g of aluminum hydroxide particles and 60 mL of hot water of about 80 ° C. were added to the beaker, and the temperature was kept at 80 ° C. for 30 minutes. The precipitate was washed out together with the solution in a 200 mL measuring flask, adjusted to the marked line after cooling, the surface sodium concentration of the supernatant was measured by JIS-K010248 atomic absorption spectrophotometry, and converted to Na ₂ O concentration.
[1% weight loss temperature]
Using TG / DTA (TG / DTA7300 high temperature type, manufactured by SII), the 1% weight loss temperature was measured and used as an index of heat resistance. The measurement sample was 10 mg, the measurement temperature range was 30 to 800 ° C., the temperature rising rate was 10 ° C./min, and the sampling time was 1 second.

Example 2
[Production of aluminum hydroxide particles B]
The aluminum hydroxide particles E were prepared and evaluated in the same manner as in Example 1 except that only the classification was performed and the pulverization was not performed, and the aluminum hydroxide particles B as a particle group having a maximum particle size of 10 μm or less were prepared.
The aluminum hydroxide particles B have a maximum particle size of 9.25 μm, an average particle size of 2.483 μm, a surface sodium concentration (Na ₂ O concentration) of 0.0016% by mass, a 1% weight loss temperature of 247.3 ° C., and a yield. Was 61.1%.

Comparative Example 1
[Production of aluminum hydroxide particles C]
Without performing classification operation, the aluminum hydroxide particles E, which are raw materials, are supplied to a pulverizer (SJ-500 manufactured by Nissin Engineering Co., Ltd.) with a quantitative supply device, and pulverized to particles having a maximum particle size of 10 μm or less. The aluminum hydroxide particles C were obtained.
The aluminum hydroxide particles C have a maximum particle size of 7.78 μm, an average particle size of 2.264 μm, a surface sodium concentration (Na ₂ O concentration) of 0.0022 mass%, a 1% weight loss temperature of 242.0 ° C., and a yield. Was 78.5%.

Comparative Example 2
[Production of aluminum hydroxide particles D]
Using a quantitative supply device, the raw material aluminum hydroxide E is supplied to a pulverizer (Nisshin Engineering Co., Ltd., SJ-500) and coarsely pulverized so that the maximum particle size is about 10 μm or less. All the pulverized particles were collected.
The collected particles are put into a classifier (TC-15 manufactured by Nissin Engineering Co., Ltd.), a particle group having a maximum particle size of 10 μm or less (aluminum hydroxide particle D-1), and a particle group having a maximum particle size of more than 10 μm ( Aluminum hydroxide particles D-2) were recovered respectively.
The aluminum hydroxide particles D-2 were pulverized and classified again by the same method to obtain a particle group (aluminum hydroxide particles D-3) having a maximum particle size of 10 μm or less. Aluminum hydroxide particles D-1 and aluminum hydroxide particles D-3 were mixed to obtain aluminum hydroxide particles D.
The aluminum hydroxide particles D have a maximum particle size of 7.78 μm, an average particle size of 2.459 μm, a surface sodium concentration (Na ₂ O concentration) of 0.0022% by mass, and a 1% weight reduction temperature of 227.0 ° C. The yield was 91.3%.

  It can be seen that the aluminum hydroxide particles of Examples 1 and 2 have a high heat resistance with a 1% weight loss temperature of 245 ° C. or higher as compared with the aluminum hydroxide particles of Comparative Examples 1 and 2. In particular, the aluminum hydroxide particles of Example 1 prepared by the production method of the present invention had a 1% weight loss temperature higher than that of the raw material particles and a high yield.

Example 3
[Manufacture of laminates]
65.4 wt.% Of bisphenol A novolac type epoxy resin (EPICRON N-865, Dainippon Ink & Chemicals, Inc., epoxy equivalent 205) as a resin component was added to 85 parts by weight of the aluminum hydroxide particles A obtained in Example 1. 34.6 parts by weight of phenol novolac resin (HF-4, hydroxyl group equivalent: 108 manufactured by Meiwa Kasei Co., Ltd.) as a curing agent, and 2-ethyl-4-methylimidazole (2E4MZ manufactured by Shikoku Kasei Co., Ltd.) as a curing accelerator ) 0.2 part by weight, spherical silica (SO-25H made by Admatex) as a filler, 30 parts by weight, zinc molybdate-carrying talc (Kemgard 911C made by Sherwin Williams) as a flame retardant aid, 5 parts by weight, And 94.4 parts by weight of methyl ethyl ketone are added and stirred and dispersed to obtain an epoxy resin composition. Prepared.

The obtained resin composition was impregnated into a glass cloth (thickness 0.1 mm # 2116, E-glass manufactured by Asahi Schavel Co., Ltd.) so that the resin content was 51% by weight, and a drying apparatus at 130 to 170 ° C. And dried for 6.4 minutes to prepare a prepreg.
Four prepregs are stacked to form a laminate, and a copper foil having a thickness of 18 μm is stacked on both sides in the stacking direction. A tension laminate was obtained.

The heat resistance of the obtained laminate was evaluated by the following method. The results are shown in Table 1.
[1% weight loss temperature]
Using the TG-DTA method, the 1% weight reduction temperature of the laminate was evaluated as heat resistance.
Using TG / DTA (TG / DTA7300 high temperature type, manufactured by SII), the 1% weight loss temperature was measured and used as an index of heat resistance. The measurement sample was 10 mg, the measurement temperature range was 30 to 800 ° C., the temperature rising rate was 10 ° C./min, and the sampling time was 1 second. Moreover, the measurement board used the laminated sheet except all the metal foils of both surfaces by the etching process.
[Solder heat resistance test]
The laminated board cut to 50 mm × 50 mm was floated on a solder bath (288 ° C.), the swelling of the copper foil was visually confirmed, and the time until the swelling occurred was measured. The maximum time was 3600 seconds.

Example 4 and Comparative Example 3-5
A laminated board was produced and evaluated in the same manner as in Example 3 except that the aluminum hydroxide particles shown in Table 1 were used instead of the aluminum hydroxide particles A. The results are shown in Table 1.

  Since the metal hydroxide particles of the present invention have both flame retardancy and heat resistance, as a flame retardant filler blended in a resin composition that is a raw material for molded products such as laminates, wiring boards, and semiconductor devices. It can be used suitably.

Claims (9)

Classifying the metal hydroxide particle group into a metal hydroxide particle group having a maximum particle size of 10 μm or less and a metal hydroxide particle group having a maximum particle size of more than 10 μm;
The metal hydroxide particle group having a maximum particle size of more than 10 μm is pulverized to have a maximum particle size of 10 μm or less, the classified maximum particle size is 10 μm or less, and the pulverized maximum particle size is Metal hydroxide particles obtained by mixing a metal hydroxide particle group of 10 μm or less,
Metal hydroxide particles having a maximum particle size of 10 μm or less and a surface sodium concentration of 0.0018% by mass or less in terms of Na ₂ O.   The metal hydroxide particles according to claim 1, having an average particle size of 2.5 to 3.5 µm. Metal hydroxide particles according to claim 1 or 2 which is aluminum hydroxide particles. Maximum particle size of the metal hydroxide particles are classified to the following metal hydroxide particles and the maximum particle size 10 [mu] m greater than the metal hydroxide particle element group 10 [mu] m,
The metal hydroxide particles having a maximum particle size of more than 10 μm are pulverized to have a maximum particle size of 10 μm or less,
Prepared by mixing the classified metal hydroxide particles having a maximum particle size of 10 μm or less and the pulverized metal hydroxide particles having a maximum particle size of 10 μm or less, and having a maximum particle size of 10 μm or less, surface sodium concentration method for producing 0.0018 mass% or less of the metal hydroxide particles in terms of Na ₂ O. The method for producing metal hydroxide particles according to claim 4, wherein the metal hydroxide particles have an average particle size of 2.5 to 3.5 μm. The method for producing metal hydroxide particles according to claim 4 or 5, wherein the metal hydroxide particles are aluminum hydroxide particles. A glass cloth is impregnated with a resin composition containing the metal hydroxide particles according to any one of claims 1 to 3 or the metal hydroxide particles obtained by the production method according to any one of claims 4 to 6. Laminated board. A laminate that is a laminate of a resin layer and a glass cloth,
The resin layer includes a filler;
The filler is classified into an aluminum hydroxide particle group having a maximum particle size of 90% or less of the thickness of the resin layer, and an aluminum hydroxide particle group having a maximum particle size of more than 90% of the thickness of the resin layer. the maximum particle diameter of the maximum particle size not more than 90% of the thickness of the resin layer was ground over 90% in a aluminum hydroxide particles of the thickness of the resin layer, is aluminum hydroxide particles obtained by grinding And aluminum hydroxide particles obtained by mixing aluminum hydroxide particles having a maximum particle size of 90% or less of the thickness of the resin layer ,
Wherein the surface sodium concentration of the aluminum hydroxide particles is not more than 0.0018 wt% in terms of Na 2 _O, laminates maximum particle size of the aluminum hydroxide particles is 10μm or less. The laminate according to claim 8 , wherein the aluminum hydroxide particles have an average particle size of 2.5 to 3.5 µm.