JPH0931167A - Liquid epoxy resin composition for sealing and cured material thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sealing epoxy resin composition having low viscosity and excellent in heat and moisture resistances by using an epoxy resin, a specified allylated phenol resin and a cure accelerator as the constituents. SOLUTION: This composition is obtained by blending an epoxy resin with an allylated phenol resin comprising an allylated novolak phenol resin which contains at most 10 area% allylated phenol aralkyl resin and/or binuclear components, in which trinuclear components account for at least 50 area% of the remaining part excluding the binuclear components and in which the total of the trinuclear component content and the tetranuclear component content is at least 75 area% in an amount sufficient to provide a stoichiometric ratio of the hydroxy groups to the epoxy groups of the epoxy resin of (0.2 to 2):1 and at least one cure accelerator selected from the group consisting of organophosphine compounds and nitrogen-containing cyclic compounds in an amount of 0.01-10 pts.wt. based on 100 pts.wt. epoxy resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid epoxy resin composition for encapsulation. More specifically, the present invention relates to a liquid epoxy resin composition for encapsulation that protects the surface of electric / electronic parts and has excellent low viscosity, heat resistance and moisture resistance.
More specifically, it can be used for electrical equipment such as IC and LSI on a circuit board.
The present invention relates to a liquid epoxy resin composition for sealing, which is intended to seal an element of an electronic component.

[0002]

2. Description of the Related Art Conventionally, ICs, LSIs, etc. are epoxy resins,
It has been used by mounting it on a substrate, which is sealed with ceramics or the like. However, in recent years, a variety of electric and electronic equipment products are required, and lighter, thinner, shorter, and smaller products are required.
It is becoming mainstream to mount using a surface mounting technique for directly connecting I etc. to a substrate. The semiconductor element directly connected to the substrate is usually sealed with liquid epoxy resin. This encapsulant is required to have a lower viscosity than the transfer molding material, and has high reliability for cured products.
Particularly, heat resistance and moisture resistance are required.

In order to meet these requirements, a liquid epoxy resin composition containing an allyl group-containing resin has been proposed. For example, JP-A-4-249526 discloses a liquid epoxy resin molding material containing an allylated novolak. However, the method for producing the allylated novolac is not disclosed, and the trade name is not described. In addition, JP-A-4-3
No. 25544 discloses a liquid epoxy resin composition containing an allyl group-containing epoxy resin obtained by partially reacting an epoxy resin with 2-allylphenol. However, since these liquid epoxy resin compositions use an acid anhydride or amines together as a curing agent component, the cured product is easily hydrolyzed and has a problem in moisture resistance. Another problem is that the frame corrodes.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid epoxy resin composition for encapsulation which has a low viscosity and is excellent in heat resistance and moisture resistance.

[0005]

The inventors of the present invention have made extensive studies to solve the above problems, and as a result, have solved the above problems and completed the present invention.

That is, the present invention provides a liquid epoxy resin composition for sealing, which comprises (A) an alicyclic epoxy resin, (B) an allylated phenolic resin (C) a curing accelerator, and

The allylated phenolic resin has an allylated phenol aralkyl type resin and a binuclear content of 10 area% or less, and the remaining trinuclear body content excluding the binuclear body is 50 area% or more. And a sealing liquid characterized by being at least one selected from the group consisting of allylated novolac-type phenolic resins having a sum of trinuclear body content and tetranuclear body content of 75 area% or more. Epoxy resin composition,
and,

A liquid epoxy resin composition for sealing, wherein the allylated phenol resin is an allylated phenol aralkyl type resin, and

The allylated phenolic resin has a binuclear content of 10 area% or less, a trinuclear content of the remaining portion excluding the binuclear is 50 area% or more, and a trinuclear content Ratio and tetranuclear content is 75% by area or more of allylated novolac type phenolic resin, Liquid epoxy resin composition for encapsulation according to claim 1,

A liquid epoxy resin composition for sealing, wherein the alicyclic epoxy resin is (3 ', 4'-epoxycyclohexylmethyl) -3,4-epoxycyclohexanecarboxylate, and

In the blending of the epoxy resin and the allylated phenolic resin, the hydroxyl group of the allylated phenolic resin is stoichiometrically 0.2 to 2 with respect to the epoxy groups of the epoxy resin. Liquid epoxy resin composition for stopping, and

The curing accelerator is at least one selected from the group consisting of organic phosphine compounds and nitrogen-containing cyclic compounds.
Liquid epoxy resin composition for sealing, characterized by being a seed, and

The amount of the curing accelerator is a cycloaliphatic epoxy resin 10
0.01 to 10 parts by weight relative to 0 parts by weight, a liquid epoxy resin composition for sealing, and

The present invention relates to a cured product of the liquid epoxy resin composition for sealing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The epoxy resin which is the component (A) used in the present invention is 1
Any curable epoxy resin having two or more epoxy groups in the molecule may be used. For example, phenol derivative epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, (3 ′,
4'-epoxycyclohexylmethyl) -3,4-epoxycyclohexanecarboxylate, (3 ', 4'-
Epoxy-6'-methylcyclohexylmethyl) -3,
Alicyclic epoxy resin such as 4-epoxy-6-methylcyclohexanecarboxylate, dicyclopentadiene-
Cyclic terpenes such as phenolic resin glycidyl ether
Examples thereof include phenol copolymer glycidyl ether. These epoxy resins may be used alone or 2
More than one type may be used in combination.

Of these, preferably (3 ', 4'-
Epoxycyclohexylmethyl) -3,4-epoxycyclohexanecarboxylate.

The allylated phenolic resin which is the component (B) of the present invention is obtained by allyl etherifying phenolic resins,
It can be obtained by a known method in which the obtained allyl etherified phenol resin is heated to undergo Claisen rearrangement.

Specifically, for example, a phenol resin as a base resin is dissolved in an organic solvent, and then an alkali is added to obtain a phenolate. To this, an allyl halide such as allyl chloride, allyl bromide or allyl iodide is added. Room temperature ~
The reaction is carried out at 100 ° C. for 1 to 5 hours to allyl etherify the phenolic hydroxyl group.

Examples of the organic solvent used here include alcohols such as n-propanol and n-butanol, ketones such as acetone and methyl ethyl ketone, and aprotic polar solvents such as N, N-dimethylformamide and dimethyl sulfoxide. . The yield of the etherification reaction product changes depending on the solvent used, but when the above organic solvent is used, the etherification reaction usually proceeds at a reaction rate of 95% or more. Since the solvent may be changed depending on the purpose of use of the resin to be obtained, any solvent in which the phenol resin and the allyl ether compound are soluble can be used. Examples of the alkali include hydroxides of alkali metals such as potassium hydroxide and sodium hydroxide. The amount used is an alkali equivalent to the phenolic hydroxyl group to be allyl etherified. The amount of allyl halide added is equal to or greater than the amount of alkali.

The allylated phenolic resin is obtained by heating the obtained allyl etherified phenolic resin to about 160 to 250 ° C. so that the allyl group which had been ether-bonded is rearranged to obtain the allylated phenolic resin of the present invention. You can This allyl group is usually rearranged to the ortho position with respect to the phenolic hydroxyl group, but it may be rearranged to the para position.

Hereinafter, regarding the allylated phenol resin,
This will be described more specifically. In order to obtain the allylated phenol aralkyl type resin of the present invention, the phenol aralkyl type resin can be used as a base resin by the above method.

The phenol aralkyl type resin is obtained as follows. With respect to 1 mol of the aralkyl compound, the phenolic compound is usually in the range of 1.0 to 4.0 mol,
Preferably, it is added in the range of 1.5 to 3.0 mol, and the temperature is raised as it is in the presence of an acid catalyst or without a catalyst, and the reaction is carried out at the temperature described below. After completion of the reaction, the resin obtained by distilling off unreacted phenol under vacuum is the above-mentioned phenol aralkyl type resin.

The phenolic compound used in this reaction may be any compound having a phenolic hydroxyl group, for example, phenol, o-cresol, p-cresol, m-cresol, 2,6-.
Examples include alkyl-substituted phenols such as xylenol and p-tert-butylphenol, aromatic-substituted phenols such as p-phenylphenol, and naphthols such as α-naphthol and β-naphthol.

As the aralkyl compound used in this reaction, an aromatic ring compound having a divalent halomethyl group, a hydroxymethyl group, an alkoxymethyl group or the like which can be condensed and added is used. For example, dihalomethyl aromatic ring compounds such as α, α′-dichloro-p-xylene, α, α′-dichloro-m-xylene, α, α′-dichloro-o-xylene, and dihydroxymethyl such as p-xylylene glycol. Aromatic ring compound, α, α'-dimethoxy-p
-Xylene, α, α'-dimethoxy-m-xylene,
Examples include dialkoxymethyl aromatic ring compounds such as α, α′-dimethoxy-o-xylene.

As the catalyst, stannic chloride, zinc chloride, ferric chloride, cupric chloride, cupric sulfate, mercuric sulfate, mercuric sulfate, mercuric chloride, mercuric chloride, Inorganic compounds such as silver sulfate, silver chloride and sodium hydrogen sulfate, sulfuric acid compounds such as sulfuric acid, monoethyl sulfuric acid, diethyl sulfuric acid and dimethyl sulfuric acid, organic compounds such as p-toluenesulfonic acid, p-phenolsulfonic acid and methanesulfonic acid Sulfonic acids are used. These catalysts may be used alone or in combination. The amount of the catalyst used is 0.01 to 5% by weight based on the total weight of the phenolic compound and the aralkyl compound.

When a dihalomethyl aromatic ring compound is used as the aralkyl compound, the reaction proceeds without using a catalyst.

The reaction temperature is usually 110 ° C. or higher. 11
When it is lower than 0 ° C, the reaction becomes extremely slow. Further, in order to shorten the reaction time, a temperature range of about 130 to 240 ° C. is desirable. The reaction time is usually 1 to 20 hours.

Furthermore, if necessary, an organic solvent having a relatively high boiling point can be used. For example, methanol, ethanol, n-propanol, isopropanol, n-
Examples thereof include alcohols such as butanol and tert-butanol, and aromatic compounds such as toluene, xylene and mesitylene.

Next, the binuclear content of the present invention is 10 area%.
The following is an allylated novolak in which the trinuclear body content of the remaining portion excluding the binuclear body is 50 area% or more, and the sum of the trinuclear body content rate and the tetranuclear body content rate is 75 area% or more. The type phenolic resin will be described in detail. The allylated novolak type phenolic resin is obtained by using the following novolak type phenolic resin with controlled distribution of the nucleus.

That is, the content of the binuclear body is 10 area% or less, the content of the trinuclear body in the remaining portion excluding the binuclear body is 50 area% or more, and the content of the trinuclear body is equal to 4 cores. An allylated novolak type phenolic resin can be obtained by the above allylation method using a novolak type phenolic resin having a total body content of 75 area% or more as a base resin.

An example of the production of the novolak type phenolic resin which is the base resin of the allylated novolak type phenolic resin of the present invention will be shown.

First, phenols are mixed with formaldehyde at a ratio of 4 to 30 times by mole (hereinafter, P / F = 4 to 30) and an acidic catalyst is added to 60 to 100.
The condensation reaction is performed at 2 ° C. for 2 to 5 hours to produce an initial condensation product. Then, the obtained initial condensate is heated under atmospheric pressure to 150-
Water and a small amount of phenols are removed by heating to about 160 ° C., and unreacted phenols are removed by heating under reduced pressure to about 160 to 180 ° C. Next, 1 to 5 m with a device equipped with packing such as McMahon packing
The temperature is further raised to 220 to 250 ° C. under reduced pressure of mHg to carry out distillation to obtain a novolac-type phenolic resin having a low content of dinuclear bodies and a high content of trinuclear bodies as a bottom product.

Examples of the phenols as the raw material of the novolac type phenolic resin include cresol, ortho or para, and meta-substituted alkylphenols in addition to phenol.

Examples of formaldehyde equivalents used include formalin, paraformaldehyde, hexamethylenetetramine, trioxane and cyclic formal. Examples of the acidic catalyst used for the reaction between the formaldehyde equivalent and the phenols include organic acids such as hydrochloric acid, sulfuric acid, paratoluenesulfonic acid and oxalic acid, and inorganic acids.

The reaction molar ratio for obtaining this novolac type phenolic resin is P / F = 4 or more, preferably 8 or more. The content ratio of the trinuclear or higher component can be roughly controlled by this reaction molar ratio, and the higher the reaction molar ratio, the higher the resin having the trinuclear content.

The binuclear content can be controlled by the temperature and pressure during distillation. The removal of the binuclear body may be carried out by vacuum distillation as described above, but it may also be carried out by extraction or steam distillation. As an extraction method, for example, the binuclear body can be removed by repeatedly washing with a poor solvent such as toluene or xylene against the phenolic resin. As the steam distillation, for example, the dinuclear body can be removed by a method of performing distillation under reduced pressure while blowing an inert gas or steam.

A resin having a low binuclear content and a high trinuclear content, which is obtained as a bottom product of this distillation, can be used as a base resin for an allylated novolac type phenolic resin.

Further, the distilled binuclear body can be utilized as useful bisphenol Fs.

As the curing accelerator which is the component (C) of the present invention, a curing accelerator used for curing general epoxy resins can be used. Preferred are organic phosphine compounds and nitrogen-containing cyclic compounds. These may be used alone or in combination of two or more.

Examples of the organic phosphine compound include phosphine compounds such as triphenylphosphine and tritolylphosphine, phosphine oxide compounds such as triphenylphosphine oxide, and phosphine-borane complexes such as triphenylphosphine / triphenylborane. However, the present invention is not limited to these. Also,
These may be used alone or in combination of two or more.

Examples of the nitrogen-containing cyclic compound include imidazole compounds such as 2-ethyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxylmethylimidazole and 2-phenyl-4,5-dihydroxylmethylimidazole. , 1,8-diazabicyclo (5,
Examples thereof include heterocyclic nitrogen-containing compounds such as 4,0) undec-7-ene, but are not limited thereto. Also,
These may be used alone or in combination of two or more.

The addition amount of the curing accelerator such as the organic phosphine compound and / or the nitrogen-containing cyclic compound is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the alicyclic epoxy resin. A particularly preferred amount of addition is from 0.05 parts by weight.
5 parts by weight.

The mixing ratio of the epoxy resin and the phenol aralkyl resin is such that the number of hydroxyl groups in the phenol aralkyl resin is stoichiometrically 0.2 to 2.0 with respect to 1 epoxy group in the epoxy resin. Is preferred.

The melt viscosity of the composition of the present invention is preferably 10 poise (100 ° C.) or less. When it exceeds 10 poise, there arises a problem that the fluidity and the molding processability are deteriorated.

In addition to the above, various components such as silica, alumina, talc, clay, and the like, flame retardants such as antimony trioxide, and colorants such as carbon black, etc., if necessary.
A flexible agent such as acrylonitrile-butadiene rubber or silicone oil can be added.

[0046]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. The evaluation or measurement of various characteristic values in the examples was carried out by the following methods (1) and (2). (1) Content of Each Nucleus and Weight Average Molecular Weight In the specification, the content of each nucleolar expressed in area% by weight average molecular weight and gel permeation chromatography (column: (manufactured by Tosoh Corporation) G4000HXL + G2500H)
XL + G2000HXL × 2, eluent: tetrahydrofuran, detector: differential refractometer). (2) Hydroxyl equivalent of phenol resin The hydroxyl group in the resin was acetylated with acetic anhydride in the presence of pyridine. Excess acetic anhydride was hydrolyzed, and the acetic acid produced was titrated with potassium hydroxide-ethanol. The hydroxyl equivalent was calculated by the following formula. OH value (KOHmg / g) = 28.05 x (BA) x
F / S OH equivalent (g / eq) = 56.11 × 1000 / OH number where A: amount of 0.5N potassium hydroxide-ethanol solution consumed for titration until the end point (ml) B: A in blank test Equivalent amount F: Factor of 0.5N potassium hydroxide-ethanol solution S: Mass of sample (3) Melt viscosity Melt viscosity was measured using an ICI cone & plate viscometer (Research Equipment Co., Ltd .: London). , 100
Measured in ° C. (4) Glass transition temperature (Tg) and storage elastic modulus (E ') Dynamic viscoelasticity is rheovibron DDV-2-EP.
(Manufactured by Toyo Baldwin Co., Ltd.). T
g is the peak temperature of tan δ. As for E ′, the value at 250 ° C. was read. The heating rate is 2.0 ° C./min,
The measurement temperature range was 50 to 350 ° C. Measurement frequency is 1
10 Hz. (5) Water absorption rate The water absorption rate of the cured product is the boiling water absorption rate, and each sample is boiled at 100 ° C / 2 hours, and the weight increase rate (F) is shown. The calculation formula is shown below. A = weight of cured product after water absorption B = weight of cured product before water absorption F = [(A−B) / B] × 100 (%)

Production Example 1 (Production of Phenol Aralkyl Resin) 714.4 g (7.60 mol) of phenol and 31.8
70 g of methanol and 0.853 g of diethylsulfate
The mixture was charged into a reactor equipped with a condenser through which cooling water at ℃ was passed, and the temperature was raised in an oil bath while stirring. When the liquid temperature reached 140 ° C, charging of α, α'-dimethoxy-p-xylene was started. 800 g (4.81 mol) of α, α'-
After dimethoxy-p-xylene was continuously charged for 4 hours, an aging reaction was further performed at a liquid temperature of 140 ° C. for 90 minutes. Next, the liquid temperature was raised to 160 ° C. and unreacted phenol was removed under reduced pressure to obtain 1025 g of resin.

Production Example 2 (Production of novolak type phenolic resin with controlled distribution of nuclide) 2000 g of phenol and 37% formalin aqueous solution 86.
Condensation reaction was carried out under the same conditions as in Production Example 1 except that 3 g was mixed (P / F = 20), water and phenol were removed, and distillation was performed at a pressure of 3 mmHg using the same apparatus.
At a final temperature of 240 ° C. to obtain the desired novolac type phenol resin as a bottom product. The resin thus obtained is referred to as Resin B. The content of each nucleus in the obtained novolac type phenolic resin (resin B) was determined by the above-mentioned method, and the content of the binuclear body was 5.4 area%. In, the trinuclear content is 83.7 area%,
The sum of the trinuclear body content rate and the tetranuclear body content rate was 97.3 area%.

Production Example 3 (Production of Allylated Phenol Aralkyl Resin) 10 equipped with a stirrer, a thermometer, a cooler, and a dropping funnel.
In a 00 ml four-necked separable flask, 360 g of isopropanol was used as a reaction solvent, 103 g of the phenol aralkyl resin obtained in Production Example 1 was dissolved, and potassium hydroxide
5.6 g was added and stirred until uniform. To this, 56.7 g of allyl chloride was added dropwise over 10 minutes, and then the reaction solution was added to 40
The mixture was stirred at 0 ° C for 1 hour and further heated and stirred at 70 ° C for 5 hours to complete the allyl etherification reaction. Then, the reaction solution was filtered to remove by-produced potassium chloride, and then isopropanol was distilled off and recovered. The residue was dissolved in ethyl acetate and washed with water, and then ethyl acetate was distilled off to obtain an allyl etherified phenol aralkyl resin. 120 g of the obtained allyl etherified phenol aralkyl resin is 300 m
The mixture was placed in a 1-separable flask and heated to 195 ° C. and stirred for 5 hours to cause thermal rearrangement to obtain an allylated phenol aralkyl resin (yield 98%, weight average molecular weight 207).
0, hydroxyl group equivalent 248 (g / eq)).

Production Example 4 (Production of allylated novolac type phenolic resin) In a 1000 ml four-neck separable flask equipped with the same stirring device, thermometer, condenser and dropping funnel as in Production Example 3,
320 g of isopropanol and 106 g of the novolac type phenol resin obtained in Production Example 3 were dissolved, and an allyl etherification reaction was carried out under the same conditions as in Production Example 3 to obtain an allyl etherified novolac type phenol resin. Next, obtained allyl etherified novolak type phenol resin 13
0 g was transferred to a 300 ml separable flask to obtain an allylated phenol resin in the same manner as in Production Example 3 (yield 96%, weight average molecular weight 400, hydroxyl equivalent 149 (g
/ Eq)).

Examples 1 to 5 Based on the compounding ratios shown in [Table 1], the allylated phenol aralkyl resin obtained in Production Example 3, the allylated novolac type phenolic resin obtained in Production Example 4, and an alicyclic epoxy resin. Resin (made by Ciba Geigy, Araldite CY-179
[Epoxy equivalent 126 g / eq]) and an imidazole compound (2E4MZ manufactured by Shikoku Kasei Co., Ltd.) were dissolved and mixed at room temperature to prepare a liquid epoxy resin composition.

Comparative Example Based on the compounding ratio shown in [Table 1], phenol novolac resin (manufactured by Mitsui Toatsu Chemicals, Inc., # 2000 [hydroxyl group equivalent 103 g / eq]), alicyclic epoxy resin (Ciba Geigy) Manufactured by Araldite CY-179 [epoxy equivalent 1
26 g / eq]) and an imidazole compound (2E4MZ manufactured by Shikoku Kasei Co., Ltd.) were dissolved and mixed at room temperature to prepare a liquid epoxy resin composition.

Preparation of Cured Product From the resin compositions obtained in Examples 1 to 5 and Comparative Example,
A cast plate of a cured product having a diameter of about 50 mm and a thickness of about 3 mm was prepared and used for evaluation of water absorption. In addition, the composition has a length of 20
A film of a cured product having a thickness of mm × width of 2 mm × 0.1 mm was prepared and used for evaluation of dynamic viscoelasticity.

[0054]

[Table 1] The unit of the composition ratio of the composition is parts by weight. The epoxy resin and the phenol resin were blended so that the epoxy groups and the hydroxyl groups were stoichiometrically equivalent.

[0055]

EFFECTS OF THE INVENTION The liquid epoxy resin composition for encapsulation of the present invention has a reduced viscosity and is considered to have excellent moldability, as can be seen from Table 1. In addition, the cured product of this composition has a high glass transition point and a high storage elastic modulus at 250 ° C., is excellent in heat resistance, and also has a low water absorption rate and good moisture resistance. Therefore, the liquid epoxy resin composition of the present invention can be effectively used for sealing applications of semiconductor devices.

Claims (9)

[Claims] 1. A liquid epoxy resin composition for encapsulation, comprising (A) an epoxy resin, (B) an allylated phenolic resin, and (C) a curing accelerator. 2. The allylated phenol resin has an allyl phenol aralkyl type resin and a binuclear content of 10 area% or less, and the remaining trinuclear body content excluding the binuclear body is 50 area. % Or more and at least one selected from the group consisting of allylated novolac type phenolic resins having a sum of trinuclear body content and tetranuclear body content of 75 area% or more. The liquid epoxy resin composition for sealing according to 1. 3. The liquid epoxy resin composition for encapsulation according to claim 1, wherein the allylated phenol resin is an allylated phenol aralkyl type resin. 4. The allylated phenolic resin has a binuclear content of 10 area% or less, a trinuclear content of the remaining portion excluding the binuclear is 50 area% or more, and trinuclear. The liquid epoxy resin composition for encapsulation according to claim 1, which is an allylated novolac-type phenolic resin having a total content of the nucleoside and the content of the tetranuclear body of 75 area% or more. 5. The epoxy resin is an alicyclic epoxy resin (3 ′, 4′-epoxycyclohexylmethyl) -3,
A liquid epoxy resin composition for encapsulation according to claims 1 to 4, which is 4-epoxycyclohexanecarboxylate. 6. The compounding of an epoxy resin and an allylated phenolic resin, characterized in that the hydroxyl groups of the allylated phenolic resin are stoichiometrically 0.2 to 2 with respect to the epoxy groups of the epoxy resin. The liquid epoxy resin composition for encapsulation according to claim 1. 7. The curing accelerator is at least one selected from the group consisting of organic phosphine compounds and nitrogen-containing cyclic compounds.
The liquid epoxy resin composition for encapsulation according to claim 1, which is a seed. 8. The encapsulating liquid epoxy resin composition according to claim 1, wherein the amount of the curing accelerator is 0.01 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin. 9. A cured product comprising the liquid epoxy resin composition for sealing according to any one of claims 1 to 8.