JPH02145642A - resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition which is used as electric or electronic parts and a sealing material, because it has excellent flow properties on molding, suitable linear expansion coefficient and static and dynamic properties, by adding spherical particles of a specific silica to a polyester thermotropic liquid crystal polymer. CONSTITUTION:A thermotropic liquid crystal polymer of polyester is combined with 10 to 80wt.% of spherical silica particles which are composed of 2 or more groups differing in particle sizes ranging from 0.05 to 150mum in which the average particle size of the minimum particle size group is less than 2mum and the size ratio of the minimum size in the large average particle size group to the maximum size in the small average particle size group is more than 2 in the two groups whose average particle sizes are approximately equal and the portion of the particles in the large average particle size is 20 to 80vol.% based on the total amount of the two groups.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a polyester-based liquid crystalline polymer composition containing spherical silica that has excellent fluidity during molding and also has excellent linear expansion coefficient and mechanical properties. It is used in electrical, electronic parts, sealing materials, etc.

[Conventional technology and problems]

So-called thermotropic liquid crystalline polymers, which form an anisotropic melt phase5, have excellent mechanical properties, coefficient of linear expansion, dimensional accuracy, and chemical resistance, as well as very good fluidity, making them suitable for precision parts. , has been developed and applied to audio-related parts, electrical and electronic parts, etc.

Especially in the case of injection molded products, in order to control the physical properties in the flow direction and in the direction perpendicular to the flow, glass fiber, carbon fiber,
A composite of inorganic fillers such as mica, talc, glass beads, and silica is used.

However, there is a report that if spherical glass beads are used among these, the fluidity is significantly deteriorated (Molecular Crystal Liquid Crystal/S Volume S77 page 19gg).

On the other hand, semiconductor elements such as ICs and LSIs are encapsulated to ensure electrical insulation and moisture resistance, and the Murakami method generally uses plastic encapsulation using resin such as ceramic encapsulation.

When a semiconductor element is sealed with resin, the stress generated due to the difference in linear expansion coefficient between the silicon chip and the resin causes deformation of the Al wiring or bonding wire, disconnection, or cracking of the bonding wire, resulting in changes in electrical characteristics. This may cause deterioration of moisture resistance. Therefore, in order to reduce these stresses, a method has been considered in which an inorganic filler is added to the resin to reduce the difference in linear expansion coefficient between the resin and the resin.

Here, in order to reduce the linear expansion coefficient difference by adding an inorganic filler to the resin, the larger the amount added, the more effective it is, but as the amount of filler added increases, the melt viscosity of the resin composition is increased, fluidity decreases, and moldability is adversely affected. Therefore, an encapsulant resin composition having sufficient performance in both linear expansion coefficient and moldability has not yet been obtained.

(Means for Solving the Problems) When semiconductor elements such as ICs and LSIs are encapsulated in plastic using resin, the present inventors used spherical silica as an inorganic filler added to the resin, and the resin had high liquid crystallinity. It was discovered that by using molecules, the resin as a whole maintains high fluidity and good moldability, and moreover, the coefficient of thermal expansion of the sealing material after molding can be highly reduced, and the present invention has been achieved.

In particular, it has been found that high filler contents may be possible if the particle size distribution is controlled under certain conditions.

An object of the present invention is to provide a resin composition that has excellent fluidity and excellent linear expansion coefficient and mechanical properties.

That is, the present invention is a resin composition formed by blending spherical silica with a polyester thermotropic liquid crystalline polymer.

The present invention will be explained in detail below.

In the present invention, a polyester thermotropic liquid crystalline polymer is used as the resin.

Here, the thermotropic liquid crystalline polymer is a polymer that can assume a liquid crystal state when melted.

Examples of such thermotropic liquid crystal polymers include aliphatic aromatic copolymer thermotropic liquid crystal polymers and wholly aromatic copolymer thermotropic liquid crystal polymers.

Examples of aliphatic aromatic copolymerized thermotropic liquid crystal polymers include polyesters called X7G and X7H (Eastman Kodanok), which can be obtained from polyethylene terephthalate and hydroxybenzoic acid, and polyethylene terephthalate and hydroxybenzoic acid. Copolymerized polyesters obtained by reacting in the presence of an acylating agent to form copolymerized oligomers and then polymerizing them are highly praised.

Examples of fully aromatic copolymerized thermotropic liquid crystalline polymers include p-hydroxybenzoic acid/biphenol/terephthalic acid terpolymers and p-hydroxybenzoic acid and terephthalic acid terpolymers.
-Those with 3:/ of oxy-4-naphthoic acid should be praised. Such wholly aromatic polyester is manufactured by Celanese Company under the trade name "Vectra".

Alternatively, the polymer may be a polymer consisting only of a diol and a dicarboxylic acid without using oxycarboxylic acid, or a thermotropic liquid crystalline polymer and mainly a polyester polymer. Further, a part of the main chain may be substituted with an amide group, ether group, ketone group, carbonate group, etc.

In the present invention, spherical silica is used as the filler.

It has been found that by using spherical silica among spherical fillers, a moldable resin composition can be obtained with almost no increase in melt viscosity, that is, almost no decrease in fluidity. is surprising.

In particular, when the particle size of the spherical silica satisfies the following conditions, it is preferable because the content of the spherical silica can be increased.

That is, spherical silica has an average particle size of 0.05 to 0 μm.
Use one that falls within the range of . This has an average particle size of 0.05
If the particle size is smaller than μm, the specific surface area of the particles is large and agglomeration is likely to occur, making it impossible to obtain a high-density compact.
This is because if particles larger than 1 m are used, as described below, when particles of different particle sizes are mixed and molded, they tend to separate from particles of other particle sizes, making uniform mixing and uniform molding difficult.

Preferably, the spherical silica is composed of two or more particle groups with different average particle diameters, and the average particle diameter of the smallest particle group among the particle groups is 28 m or less. Yes, more preferably /, 0 μm
The following is good. Furthermore, in two particle groups whose average particle sizes are close to each other, the minimum particle size within the range defined by the standard deviation value of the particle size of the particle group with the larger average particle size, and the particle group with the smaller average particle size. The ratio of the maximum particle diameters within the range defined by the standard deviation value of particle diameters is 2 or more, preferably S or more. Furthermore, [phase] the ratio of the total volume of the particle group with the larger average particle size to the total volume of the two particle groups with average particle sizes close to each other is in the range of 20 to 1%, more preferably SO to ? It is good that it is 5vo1%. These conditions◎
To further explain 0@, when the average particle diameter of the particle group with the smallest average particle diameter becomes larger than 2 μm, the voids generated in the molded article also become larger.

θ is defined by the standard deviation value of the minimum particle size within the range defined by the standard deviation value of the particle size of the particle group with the larger average particle size among the particle groups in which the average particle size in the particles is close to each other. It is defined by the standard deviation value of the particle size of a group of particles with a small average particle size and the minimum particle size of the range. <<
Also, if the volume of a particle group with a larger average particle size to the total volume of two particle groups with average particle sizes close to each other is less than 20 vol. Large particles exist in a scattered manner, resulting in poor filling efficiency, and conversely, when the volume of particles with a large average particle size is The filling efficiency is poor because the volume ratio of small particles filling the space is small.

In addition, it is generally desirable for the particle size distribution of each particle group to be relatively narrow. For example, a standard deviation value of 2 or less, more preferably /, 5 or less, and most preferably 762 or less is selected. However, it is not necessary to adhere to this in each specific situation.

That is, if the particle size ratio under the above condition O is quite large, that is, if there is a size difference of 1.2 equivalent to the particle size of the main part of the Ω particle groups, then the particles of each particle group Although the size distribution is relatively wide, the spaces between the large particles are sufficiently filled with small particles.
It is also possible that a void serving as the apex may not be created. Therefore, the particle size distribution of each particle group may be selected appropriately depending on each case, taking into consideration the particle size ratio under condition 0.

Spherical silica that satisfies the above conditions of average particle size, particle size distribution, average particle size ratio of particles, and volume ratio of particles is kneaded with polyester thermotropic liquid crystalline polymer and other additives. Therefore, by efficiently filling the gaps between particles with a large average particle size with particles with a small average particle size, the amount of inorganic filler added to the entire resin composition can be increased while maintaining a high degree of fluidity. becomes possible.

Spherical silica may be mixed with resin as it is, but it is preferable to use a surface treatment agent in terms of fluidity, mechanical properties, etc.

The surface treatment agent used is preferably a silane coupling agent, particularly an epoxy-containing silane coupling agent, an amine-containing silane coupling agent, or the like. Among these, amine-containing silane coupling agents are preferred from the viewpoint of fluidity.

The content of spherical silica is 10 to 8 based on the entire resin composition.
It is preferable to mix it so that it becomes 0 wt%. 10w
When it is less than t%, the coefficient of linear expansion tends to become large (both in the flow direction and in the direction perpendicular to the flow direction), which is not preferable. When it exceeds 80 wt%, the fluidity tends to deteriorate extremely or disappear, which is not preferable.

In particular, it is preferable to blend /left~7S~vt%.

Such a resin composition has a low coefficient of linear expansion, good heat resistance, and high fluidity (it can be used as a resin composition with good moldability).

A general method for preparing the resin composition of the present invention as a molding material is to tri-blend raw material components selected at a predetermined blending ratio using a Henschel mixer or the like, and then knead them using a twin-screw extruder or the like. It is preferable to pelletize it.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples unless it departs from the gist thereof.

Resin A> Polyethylene terephthalate oligomer (η□nh=o
, //dl/9 ) / 9.2 kg (/oo mol) and p-hydroxybenzoic acid left! ;, 2 kg (4t0
0 mol), acetic anhydride qO,g kg, and stannous acetate, 2 u, 32 g were charged into a polymerization tank equipped with a stirrer, and after purging with nitrogen three times, the polymerization tank was heated to 750 °C and heated to 750 °C. Stir for 7 hours and heat at 110°C for 7 hours without distilling off the acetic acid.
The mixture was further stirred at λlIo°C for 7 hours. Furthermore, the temperature of the polymerization tank was raised to 27J-°C, and the pressure was gradually reduced while distilling acetic acid, and after 30 minutes, the pressure was reduced to 0. /! r) nzHg.

Next, the polymerized thread was returned to normal pressure with N2 to give y of zinc acetate dihydrate.
o, g After adding g 0. The polymerization was completed by stirring under a vacuum of Hg / g Hg for 2 hours, and the mixture was taken out from the polymerization tank and pelletized using a pelletizer.

The melt viscosity of this resin is /10 poise at 300°C and 3005ec-1, and as a result of hot stage polarized light microscopic observation, it is possible to flow in the range of 2.20°C to 350°C, and it can be used as a liquid crystal in the same temperature range. observed to exhibit sex. This resin will be referred to as Resin A.

<Resin B> Resin B is a pellet of fully aromatic polyester "Pectra" Aqso (trade name) manufactured by Celanese Company.

Example/~g Monodispersed spherical silica with an average particle size of /, 3,311 m, standard deviation (σ) /, '+ as spherical silica was triblended with resin A in the proportions shown in Table -/, and then twin-screw extruded. The machine turned into a crosstalk beret. The melt viscosity of the pellet was measured using a flow tester (manufactured by Shimadzu Corporation, trade name: CFT-400), and the fluidity was evaluated.

Further, a pellet was molded using an injection molding machine, a part of the obtained molded product was cut out, and its linear expansion coefficient (αT) was measured in the machine direction (MD) and the direction perpendicular to this (TD). The coefficient of linear expansion (αT) was measured using a thermomechanical analyzer (Seiko Electronics ■, trade name: TMA-/0).

The results are shown in Table-/. The results of Resin A without adding spherical silica are shown as Reference Example/.

Example 9~// As spherical silica, average particle size 2.2 μm, standard deviation (σ
)/, ll monodispersed spherical silica (abbreviated as large particle silica)
A mixture of monodisperse spherical silica (abbreviated as small particle silica) with an average particle diameter of O0S μm and a standard deviation (σ) of 7.05 in the proportions shown in Table -/ is triblended with Resin A in the proportions shown in Table -/. The following procedure was carried out in the same manner as in Example. The results are shown in Table-/.

Comparative Example - The same procedure as in Example was carried out except that crushed irregular angular silica and spherical glass beads were used instead of cospherical silica. The results are shown in Table-/.

Example/2~/O The same average particle size as used in Example/ as spherical silica/
3. Monodispersed spherical silica having Sμm and standard deviation (σ)/, II was triblended with resin B in the proportions shown in Table 2, and the following procedure was carried out in the same manner as in Example. The results are shown in Table C.

The results obtained by adding no spherical silica to Resin B are shown as Reference Example C.

Example/7 Average particle size O, S μm, standard deviation (σ) /, 0! r
The same procedure as in Example 1 was carried out using monodispersed spherical silica and resin B in the proportions shown in Table 1. The results are shown in Table 2.

Example/g~koO As spherical silica, average particle size, 22 μm, standard deviation (σ
) /, monodisperse spherical silica (large particle silica) of RI and monodisperse spherical silica (small particle silica) of average particle size o, S μm, standard deviation (σ) /, 03 were mixed in the proportions listed in Table 2. The mixture was triblended with Resin A in the proportions shown in Table 1, and the same procedure as in Example 1 was carried out. The results are shown in Table-2.

Comparative Examples 3 to 1 The same procedure as Example 2 was carried out except that crushed irregular angular silica and spherical glass beads were used instead of spherical silica. The results are shown in Table-2.

(Effects of the Invention) According to the present invention, high fluidity can be obtained and/or the amount of inorganic filler can be increased.

Therefore, it is expected to obtain an IC encapsulant resin composition that has a high inorganic filler content (therefore, a low coefficient of thermal expansion and excellent heat resistance, as well as high fluidity and excellent moldability). Value is a dog.

Claims (2)

[Claims] (1) A resin composition formed by blending spherical silica with a polyester thermotropic liquid crystalline polymer. (2) A composition comprising 10 to 80 wt% of spherical silica having an average particle diameter of 0.05 to 150 μm based on the entire resin composition, wherein the spherical silica is (a) two groups having different average particle diameters. Consisting of the above particle groups, (b) The average particle size of the particle group with the smallest average particle size is 2 μm.
(c) The minimum particle size within the range defined by the standard deviation value of the particle size of the particle group with the larger average particle size and the smaller particle size of the particle group with the larger average particle size in two particle groups with average particle sizes close to each other. The ratio of the maximum particle size in the range defined by the standard deviation value of the particle size of the particle group is greater than or equal to λ, and (d) the average particle size is larger than the total volume of the two particle groups whose average particle sizes are close to each other. The resin composition according to claim 1, characterized in that the resin composition is spherical silica particles in which the proportion of the total volume of the particle group is 20 to 80 vol%.