WO2010061793A1

WO2010061793A1 - Phenol resin molding material and phenol resin molded article

Info

Publication number: WO2010061793A1
Application number: PCT/JP2009/069714
Authority: WO
Inventors: 辰雄平林; 正法三好
Original assignee: パナソニック電工株式会社
Priority date: 2008-11-25
Filing date: 2009-11-20
Publication date: 2010-06-03
Also published as: JP5416717B2; JPWO2010061793A1

Abstract

Disclosed is a phenol resin molding material which has improved storage stability, kneading stability and moldability before curing, while exhibiting improved heat resistance, dimensional accuracy and dimensional stability after curing. The phenol resin molding material contains a novolac phenol resin, a polyvinyl acetate-modified novolac phenol resin, and a filler. Silica is contained therein as the filler in an amount of 75-90% by mass relative to the total amount of the phenol resin molding material.

Description

Phenolic resin molding materials and phenolic resin moldings

The present invention relates to a phenol resin molding material used for molding various molded products and a phenol resin molded product molded using the phenol resin molding material.

Engineering plastics and epoxy resin materials are used as substitutes for metal and ceramic parts used in electrical and electronic parts and automotive parts, but these substitute materials are more resistant to heat than metal and ceramic parts. In terms of dimensional stability, it is still not close to that area.

In recent years, particularly in the electronics field, miniaturization and high precision have been pursued, and the requirements for heat resistance and dimensional stability of molded products have become more severe.

Under such circumstances, the phenol resin molding material is excellent in heat resistance and is expected as a substitute material for metal and ceramic parts (see, for example, Patent Document 1), but compared with metal and ceramic parts. Further, since the molding shrinkage ratio, anisotropy and linear expansion coefficient are large, improvement in dimensional accuracy has been a problem.

That is, the phenol resin undergoes a chemical change and physical change such as a curing reaction and cooling in the molding process, causes a volume change, and shrinks after molding. In addition, phenol resin is blended with fillers such as inorganic fillers, but since the volume change of this inorganic filler is much smaller than that of phenol resin, a large residual strain is formed on the interface between the inorganic filler and phenol resin after molding. Occurs. Especially in the case of fibrous or plate-like anisotropic inorganic fillers, the strain direction is non-uniform because it is oriented during material flow, and there is a difference in molding shrinkage and dimensional changes after moisture absorption and heat treatment, resulting in warping and strain. appear.

Furthermore, since such warpage and distortion vary depending on the shape and molding conditions of the molded product, it is difficult to obtain a product with stable dimensional accuracy.

In addition, when metal is insert-molded, if the thermal expansion coefficient differs between the resin material and the metal, cracks may occur in the molded product or interface peeling may occur.

Particularly in phenol resin molding materials, in order to improve dimensional stability, reinforcing fibers such as glass fibers are usually used frequently as reinforcing fillers to be blended with phenol resins. As described above, as a technique for reducing the molding shrinkage rate and the linear expansion coefficient, it is generally used to fill with a high amount of an inorganic filler. However, with such a technique, kneading stability and moldability during production are remarkably increased. Damaged.

On the other hand, epoxy resin materials for semiconductor encapsulation that are highly filled with fused silica have a high shrinkage rate, anisotropy, and thermal expansion coefficient without sacrificing kneading stability and moldability during production by being filled with fused silica. Can be reduced. However, the molded product obtained by curing the epoxy resin molding material changes with time due to moisture absorption, so it is difficult to use in precision parts that require dimensional accuracy on the micron order. Improvement of dimensional stability is an issue. Moreover, since an epoxy resin molding material is inferior in heat resistance as compared with a phenol resin molding material, a problem remains even in use in a high temperature environment. Furthermore, the epoxy resin molding material required refrigerated transportation and storage at 10 ° C. or lower.

JP 2008-184488 A

The present invention has been made in view of the above points, and without causing damage to the heat resistance and moldability inherent in the phenolic resin, by reducing the molding shrinkage rate and anisotropy, warping and distortion are generated. Phenol, which can suppress cracking and peeling of the interface between the metal and the resin material by reducing the thermal expansion coefficient, and can suppress dimensional change due to moisture absorption or heat treatment. Resin molding materials and phenolic resin molded products, that is, before curing, storage stability, kneading stability and moldability can be improved, and after curing, heat resistance, dimensional accuracy and dimensional stability are improved. It is an object of the present invention to provide a phenol resin molding material and a phenol resin molding product that can be made to be produced.

In addition, the phenol resin molding material containing only silica as a filler is extremely low viscosity and excellent in fluidity compared with the conventional phenol resin molding material containing glass fiber, but it exists in the mold. Gas or gas generated from the material during molding is entrained in the material to cause poor filling, and since molding pressure cannot be applied sufficiently, defective molding occurs on the surface of the molded product, which is released from the mold. It causes a defect. Further, when silica is highly filled, rigidity is increased and resistance when the mold is removed from the mold is increased. Therefore, when the molded article is taken out from the mold, the molded article may be cracked or chipped.

Therefore, the present invention has been made in view of the above points, and the mold release resistance when taking out a molded product from a mold is good even when continuously molded without deteriorating fluidity. Another object is to provide a phenolic resin molding material and a phenolic resin molded product capable of reducing the above.

The phenol resin molding material according to claim 1 of the present invention is a phenol resin molding material containing a novolac type phenol resin, a polyvinyl acetate-modified novolac type phenol resin, and a filler, wherein silica is the phenol resin molding material. It is characterized by containing 75 to 90% by mass with respect to the total amount.

The invention according to claim 2 is characterized in that, in claim 1, the polyvinyl acetate-modified novolak type phenol resin is contained in an amount of 20 to 80% by mass based on the total amount of the phenol resin.

The invention according to claim 3 is characterized in that, in claim 1 or 2, 15 to 40% by mass of novolac type phenol resin having a weight average molecular weight of 20000 or more is contained with respect to the total amount of novolac type phenol resin. It is.

The invention according to claim 4 is characterized in that, in any one of claims 1 to 3, the particle size of silica is 100 μm or less.

The invention according to claim 5 is characterized in that, in any one of claims 1 to 4, the silica is spherical.

The invention according to claim 6 is the method according to any one of claims 1 to 5, wherein the silica having an average particle diameter of 10 to 30 μm is 80 to 95% by mass and the average particle diameter is 0.5 to 5 μm with respect to the total amount of silica. It is characterized by containing 5 to 15% by mass of silica.

The invention according to claim 7 is characterized in that boric acid is contained in any one of claims 1 to 6.

The invention according to claim 8 is characterized in that in any one of claims 1 to 7, an elastomer is contained.

The phenol resin molded product according to claim 9 of the present invention is characterized by being formed by molding the phenol resin molding material according to any one of claims 1 to 8.

According to the phenol resin molding material according to claim 1 of the present invention, it is possible to improve storage stability, kneading stability and moldability before curing, and after curing, heat resistance, dimensional accuracy and Dimensional stability can be improved.

According to the invention of claim 2, when the content of the polyvinyl acetate-modified novolac phenol resin is 20% by mass or more, dimensional accuracy and dimensional stability can be further improved, When the content of the polyvinyl acetate-modified novolac phenol resin is 80% by mass or less, the molding cycle can be further shortened.

According to the invention of claim 3, the mold releasability is good even if continuously molded without impairing the fluidity, and the mold release resistance when taking out the molded product from the mold can be reduced. is there.

According to the invention of claim 4, the dimensional accuracy can be further improved by improving the surface smoothness.

According to the invention which concerns on Claim 5, while improving the fluidity | liquidity at the time of shaping | molding, while improving kneading | mixing stability and a moldability, it can prevent that facilities, such as a metal mold | die, wear. It can be done.

According to the invention of claim 6, kneading stability and moldability can be further improved before curing, and dimensional accuracy and dimensional stability can be further improved after curing. is there.

According to the seventh aspect of the present invention, the degree of surface hardening after curing of the molded product is improved and good mold release properties can be obtained while preventing a decrease in kneadability before curing.

According to the invention of claim 8, it is possible to obtain the effect of reducing elasticity while reducing the mechanical properties of the molded product and to reduce the mold release resistance.

The phenol resin molded product according to claim 9 of the present invention is excellent in heat resistance, dimensional accuracy and dimensional stability.

Hereinafter, embodiments of the present invention will be described.

In the present invention, the phenolic resin molding material contains a polyvinyl acetate-modified novolac type phenolic resin, other novolac type phenolic resin, and a filler. As another phenolic resin, a resol type phenolic resin is used. It may be contained.

The polyvinyl acetate-modified novolac type phenol resin is prepared by, for example, reacting phenol, formalin (about 50% aqueous solution) and oxalic acid at 100 ° C. for 90 minutes, and emulsifying the mixture over 120 minutes. It can be obtained by adding (weight average molecular weight 10,000 to 20,000), cooling and solidifying a material treated at a temperature of 160 ° C. in an atmosphere of 520 mmHg (69.3 kPa), and pulverizing the solidified product. By using such a polyvinyl acetate-modified novolac type phenol resin, the linear expansion coefficient of the molded product can be reduced, and the dimensional stability of the molded product in a high-temperature atmosphere can be improved.

Further, it is preferable to contain 20 to 80% by mass of the polyvinyl acetate-modified novolak type phenol resin with respect to the total amount of the phenol resin. As described above, when the content of the polyvinyl acetate-modified novolak phenol resin is 20% by mass or more, the dimensional accuracy and the dimensional stability can be further improved. A molding cycle can be shortened more as content of resin is 80 mass% or less. However, if the content of the polyvinyl acetate modified novolak type phenol resin is less than 20% by mass, the effect of improving the dimensional accuracy and dimensional stability may be reduced. If the amount exceeds 80% by mass, the molding cycle during production of the molded product may be deteriorated. Although the reason for this is not clear, it is considered that polyvinyl acetate inhibits the curing of the phenol resin.

Further, it is preferable that 15 to 40% by mass of a high molecular weight novolak type phenol resin having a weight average molecular weight (polystyrene conversion) of 20000 or more (upper limit is 100,000) is contained with respect to the total amount of the novolak type phenol resin. More preferably, the content is 35% by mass. Thereby, without deteriorating the fluidity, the mold releasability is good even when continuously molded, and the mold release resistance when taking out the molded product from the mold can be reduced. However, if the content of the high molecular weight novolak type phenol resin is less than 15% by mass, the melt viscosity of the phenol resin molding material becomes too low, and there is a possibility that a mold release failure due to poor filling may occur. If the content of the high molecular weight novolak type phenolic resin exceeds 40% by mass, the melt viscosity of the phenolic resin molding material becomes too high, so that the fluidity is lowered and the moldability may be deteriorated. Further, when the weight average molecular weight of the novolac type phenol resin is less than 20000, the melt viscosity of the phenol resin molding material becomes too low, and there is a possibility that a release failure due to a filling failure may occur.

Further, the phenol resin is preferably contained in an amount of 8 to 25% by mass, more preferably 10 to 20% by mass, based on the total amount of the phenol resin molding material. When the content of the phenol resin is less than 8% by mass, the kneading stability is remarkably deteriorated and the moldability may be lowered. Conversely, when the content of the phenol resin exceeds 25% by mass, the molding shrinkage rate or As the linear expansion coefficient increases and the dimensional change with time after the moisture resistance treatment increases, there is a possibility that good dimensional accuracy cannot be obtained. In addition, the said phenol resin means what contains a polyvinyl acetate modified novolak-type phenol resin and a novolak-type phenol resin other than this at least.

Further, silica is used as the filler, and the silica is contained in an amount of 75 to 90% by mass, preferably 80 to 88% by mass based on the total amount of the phenol resin molding material. However, when the silica content is less than 75% by mass, the molding shrinkage rate and the linear expansion coefficient increase. Conversely, when the silica content exceeds 90% by mass, the kneading stability is remarkably deteriorated and the moldability is increased. Decreases.

Here, the silica particle size is preferably 100 μm or less. When such silica is used, the surface smoothness is improved, so that the dimensional accuracy can be further improved. In particular, precision parts that require dimensional accuracy on the micron order can be easily produced without problems. It is something that can be done. However, if the particle size of silica exceeds 100 μm, the effect of improving the surface smoothness may not be obtained.

Further, the silica is preferably spherical. Thus, when the shape of the silica is spherical, the flowability during molding can be improved, so that kneading stability and moldability can be further improved, and the equipment such as molds can be prevented from being worn. Is something that can be done. However, when the shape of the silica is other than spherical, for example, in the form of fibers or plates, the fluidity at the time of molding is not sufficiently improved due to the entanglement of silica and the effect of improving kneading stability and moldability. There is a risk that it may not be obtained, or equipment such as a mold may be worn out.

As silica, two or more types having different average particle diameters can be used in combination. In this case, it is particularly preferable to contain 80 to 95% by mass of silica having an average particle size of 10 to 30 μm and 5 to 15% by mass of silica having an average particle size of 0.5 to 5 μm, based on the total amount of silica. Thus, by setting the average particle size and content of silica, kneading stability and moldability can be further improved before curing, and dimensional accuracy and dimensional stability can be improved after curing. It can be further improved. However, if the average particle size and content of silica deviate from the above ranges, there is a possibility that neither the effect of improving kneading stability and moldability nor the effect of improving dimensional accuracy and dimensional stability can be obtained. The average particle diameter of silica can be measured by a laser diffraction / scattering method.

Further, it is preferable that the phenol resin molding material contains boric acid as a curing aid. As described above, when boric acid is contained, the degree of surface hardening after curing of the molded product is improved and good releasability can be obtained while preventing deterioration of kneadability before curing. is there. In order to obtain such an effect more reliably, it is preferable to contain 0.1 to 0.5% by mass of boric acid with respect to the total amount of the phenol resin molding material. If the boric acid content is less than 0.1% by mass, the degree of surface hardening after curing of the molded product may be insufficient, and the mold release property may be deteriorated. Conversely, the boric acid content is 0.5. If it exceeds mass%, the kneadability may be reduced.

Moreover, it is preferable that the phenol resin molding material contains an elastomer. As the elastomer, for example, NBR, SBR, acrylic rubber, silicone resin, polybutadiene and the like can be used. When such an elastomer is contained, it is possible to obtain a low elasticity effect and to reduce the mold release resistance while preventing the deterioration of the mechanical properties of the molded product. In order to obtain such an effect more reliably, the elastomer is preferably contained in an amount of 0.3 to 5% by mass, more preferably 0.5 to 3% by mass, based on the total amount of the phenol resin molding material. . If the elastomer content is less than 0.3% by mass, it is difficult to obtain a low elasticity effect, and the release resistance may not be reduced. Conversely, if the elastomer content exceeds 5% by mass, There is a risk that the mechanical properties of the molded product may be deteriorated.

And a phenol resin molding material can be manufactured as follows. First, a polyvinyl acetate modified novolak type phenolic resin, other novolak type phenolic resin, and a filler are mixed, and if necessary, a curing agent such as hexamethylenetetramine and a release agent such as zinc stearate. Then, a pigment such as carbon black, a coupling agent such as an aminosilane coupling agent, and the like are mixed, and this mixture is kneaded at a temperature of 100 to 110 ° C. for 2 to 5 minutes using a biaxial kneader such as a biaxial roll. Next, the kneaded product is cooled and solidified, and the solidified product is pulverized and then granulated, whereby a phenol resin molding material can be obtained. In the phenol resin molding material obtained in this way, storage stability, kneading stability and moldability can be improved before curing, and after curing, heat resistance, dimensional accuracy and Dimensional stability can be improved.

Next, using the phenol resin molding material obtained as described above, various phenol resin molded products can be formed by molding by hot pressing, injection molding, transfer molding, compression molding, or the like. The molded product thus obtained is excellent in heat resistance, dimensional accuracy and dimensional stability.

That is, according to the present invention, by reducing the molding shrinkage ratio, anisotropy, and thermal expansion coefficient without impairing the heat resistance, mechanical properties, and moldability inherent to the phenolic resin, it can be obtained from conventional resin materials. It is possible to obtain a molded article having a very high level of dimensional accuracy and dimensional stability that is not possible. Further, even when the metal is insert-molded using the phenol resin molding material of the present invention, cracks and interface peeling do not occur. Furthermore, the dimensional change with time due to moisture absorption or heat treatment can be reduced in the molded article of the present invention. Moreover, the phenolic resin molding material of the present invention is excellent in storage stability and can be transported and stored at room temperature.

In addition, precision parts that have conventionally been processed by cutting metal or ceramics can be processed by molding if the phenolic resin molding material of the present invention is used, so that the number of processing steps can be greatly reduced. It is expected to lead to improvement in design freedom.

Also, parts that have already been made into resin can achieve higher dimensional accuracy and dimensional stability by using the phenol resin molding material of the present invention.

For example, the molded product can include a camera lens holding part of a mobile phone, a gas meter part, an optical fiber connector part, an OA equipment part, a fuel pump part of an automobile, etc. Expected to be used for parts that require stability.

Hereinafter, the present invention will be specifically described by way of examples.

(Examples 1 to 8 and Comparative Examples 1 to 4)
“TNR” (weight average molecular weight of about 3000) manufactured by Panasonic Electric Works Co., Ltd. was used as the polyvinyl acetate modified novolak type phenol resin. As other novolak-type phenolic resins, “PAR” (weight average molecular weight: 2000 to 4000) manufactured by Panasonic Electric Works Co., Ltd. was used.

In addition, as a filler, “HS-201” (microparticle size is 100 μm or less, spherical, average particle size 24 μm) which is fused silica, which is fused silica, and “HS-301” (particles, which is fused silica, which is fused silica) The diameter is 100 μm or less, spherical, average particle size 2.4 μm), “Wollastonite NYAD400” manufactured by NYCO, and “CS3E-479S” manufactured by Nitto Boseki Co., Ltd., which is a glass fiber (fiber diameter average φ12 μm, fiber length 3 mm) ) Was used.

In addition, hexamethylenetetramine (“S-4” manufactured by Mitsui Toatsu Co., Ltd.) is used as the curing agent, zinc stearate (“SZ-P” manufactured by Sakai Chemical Industry Co., Ltd.) is used as the release agent, and the pigment is used. Carbon black was used, and an aminosilane coupling agent was used as the coupling agent.

And in the compounding quantity (mass%) shown in the following [Table 1], polyvinyl acetate modified novolak type phenol resin, other novolac type phenol resin, filler, curing agent, release agent, pigment, coupling agent. The mixture was mixed for 1 minute, and this mixture was kneaded for 3 minutes at a temperature of 100 to 110 ° C. by a twin-screw kneader. Next, the kneaded product was cooled and solidified, and the solidified product was pulverized and granulated to produce a phenol resin molding material.

Next, various measurements and measurements were performed on the phenolic resin molding material obtained as described above, as described below.

1. Bending strength, bending elastic modulus, molding shrinkage rate Using the above phenol resin molding material, a test piece was produced based on JISK6911 by injection molding (molding temperature 165 ° C., curing time 70 seconds). And based on JISK6911, the bending strength, bending elastic modulus, and molding shrinkage rate of the test piece were measured.

2. Linear expansion coefficient A test piece having a size of φ5 mm × 15 mm was produced by direct pressure molding (mold temperature: 165 ° C., pressure: 10 MPa, curing time: 180 seconds) using the phenol resin molding material. And the linear expansion coefficient of the test piece was measured by the TMA method.

3. Melt viscosity (minimum torque)
The phenol resin molding material was kneaded with a lab plast mill, and the torque (minimum torque) when the torque during melting was lowest was measured.

4). Curing time The phenol resin molding material was kneaded with a lab plast mill, and the time from when the phenol resin molding material melted until the curing reaction progressed until the torque value reached 5 kgf · m was measured as the curing time.

5). Moisture-resistant dimensional change Using the above phenol resin molding material, a test piece (90 mmφ) was produced based on JISK6911 by injection molding (molding temperature 165 ° C., curing time 70 seconds). And this test piece was put into a 40 degreeC * 90% RH high-temperature, high-humidity tank for 1000 hours, and the dimensional change rate with respect to an initial dimension was measured.

6). Change in heat-resistant dimension Using the above phenol resin molding material, a test piece (90 mmφ) was produced based on JISK6911 by injection molding (molding temperature 165 ° C., curing time 70 seconds). And this test piece was put into a 200 degreeC high temperature tank for 1000 hours, and the dimensional change rate with respect to the initial dimension was measured.

The measurement and measurement results of the above items are shown in [Table 1] below.

(Examples 9 to 18)
“TNR” (weight average molecular weight of about 3000) manufactured by Panasonic Electric Works Co., Ltd. was used as the polyvinyl acetate modified novolac type phenol resin. As other novolak-type phenol resins, “PAR” (weight average molecular weight 2000 to 4000) manufactured by Panasonic Electric Works Co., Ltd. and “BRM595” (weight average molecular weight 28000) manufactured by Showa Polymer Co., Ltd., which is a high molecular weight, were used.

As the filler, “HS-201” (particle size is 100 μm or less, spherical, average particle size 24 μm) manufactured by Micron Corporation, which is fused silica, was used.

Further, boric acid was used as a curing aid, and “Nipol 1411” manufactured by Nippon Zeon Co., Ltd., which is NBR, was used as an elastomer.

And with the compounding quantity (mass%) shown in the following [Table 2], a polyvinyl acetate modified novolak-type phenol resin, other novolak-type phenol resins, fillers, curing agents, curing aids, elastomers, release agents, The pigment and the coupling agent were mixed for 1 minute, and this mixture was kneaded for 3 minutes at a temperature of 100 to 110 ° C. by a biaxial kneader. Next, the kneaded product was cooled and solidified, and the solidified product was pulverized and granulated to produce a phenol resin molding material.

1. Bending strength, flexural modulus, molding shrinkage rate Using the above phenol resin molding material, a test piece was prepared based on JISK6911 by transfer molding (molding temperature 165 ° C., curing time 90 seconds). And based on JISK6911, the bending strength, bending elastic modulus, and molding shrinkage rate of the test piece were measured.

2. Linear expansion coefficient A test piece was prepared based on JISK6911 by transfer molding (molding temperature: 165 ° C., curing time: 90 seconds) using the phenol resin molding material. And the linear expansion coefficient of the test piece was measured by the dilatometer method.

4). Release property 50 shots of injection molding using the above-mentioned phenol resin molding material were continuously carried out, and the release property was evaluated by three items of mold haze, release resistance, and molded product surface peeling.

Mold haze (visually) was determined according to the following criteria.

○: Mold is not cloudy Δ: Mold is slightly cloudy ×: Mold is cloudy The mold release resistance was determined according to the following criteria.

○: No release resistance Δ: Gradually increased release resistance ×: High release resistance from the beginning Molded product surface peeling was determined according to the following criteria.

○: No peeling on the surface of the molded product. Δ: No peeling on the surface of the molded product after 30 shots. X: No peeling on the surface of the molded product from the beginning. Moisture-resistant dimensional change A test piece (90 mmφ) was prepared based on JISK6911 by transfer molding (molding temperature: 165 ° C., curing time: 90 seconds) using the phenol resin molding material. Then, this test piece was placed in a high-temperature and high-humidity tank of 40 ° C. × 90% RH for 250 hours, and the dimensional change rate relative to the initial dimension was measured.

6). Change in heat-resistant dimension Using the above phenol resin molding material, a test piece (90 mmφ) was produced based on JISK6911 by transfer molding (molding temperature: 165 ° C., curing time: 90 seconds). And this test piece was put into a 200 degreeC high temperature tank for 250 hours, and the dimensional change rate with respect to an initial dimension was measured.

The measurement and measurement results of the above items are shown in [Table 2] below.

Claims

A phenolic resin molding material containing a novolac type phenolic resin, a polyvinyl acetate modified novolac type phenolic resin, and a filler, wherein silica is contained in an amount of 75 to 90% by mass based on the total amount of the phenolic resin molding material. A phenolic resin molding material characterized by
The phenolic resin molding material according to claim 1, wherein the polyvinyl acetate-modified novolac type phenolic resin is contained in an amount of 20 to 80% by mass based on the total amount of the phenolic resin.
3. The phenolic resin molding material according to claim 1, wherein 15-40% by mass of a novolac type phenol resin having a weight average molecular weight of 20000 or more with respect to the total amount of the novolac type phenol resin is contained.
The phenol resin molding material according to any one of claims 1 to 3, wherein the particle diameter of silica is 100 µm or less.
The phenol resin molding material according to any one of claims 1 to 4, wherein the silica is spherical.
2. The silica according to claim 1, wherein 80 to 95% by mass of silica having an average particle diameter of 10 to 30 μm and 5 to 15% by mass of silica having an average particle diameter of 0.5 to 5 μm are contained with respect to the total amount of silica. The phenolic resin molding material according to any one of 5.
The phenol resin molding material according to any one of claims 1 to 6, wherein boric acid is contained.
The phenol resin molding material according to any one of claims 1 to 7, wherein an elastomer is contained.
A phenolic resin molded product formed by molding the phenolic resin molding material according to any one of claims 1 to 8.