JPS6274955A - Sealing polyester resin composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which has excellent flow characteristics, is low-pressure injection-moldable and has excellent resistance to water and heat, etc., by blending a polyester mainly composed of polyethylene terephthalate with a nucleating agent, an ester plasticizer and a terminal blocking agent. CONSTITUTION:100pts.wt. polyester (A) wherein at least 80mol% of repeating units are composed of ethylene tetraphthalate units is blended with at least 0.05pts.wt. nucleating agent (B) (e.g., mica, silica), 0.3-10pts.wt. ester plasticizer (C) (e.g., compds. of formulas I, II) and a terminal blocking agent (D) (e.g., tripropylene glycol diglycidyl ether, diphenylmethane diisocyanate) in an amount of 0.5-5 times by equivalent the amount of carboxyl groups in the component A to obtain the desired sealing polyester resin compsn. The resin compsn. is particularly suitable for use in sealing electric and electronic components which are liable to be broken or deformed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyester resin composition for sealing that has good fluidity and provides molded articles with excellent water resistance and heat resistance. More specifically, it can be molded with low injection pressure during injection molding, and the resulting molded product has improved water resistance and high heat distortion temperature, etc., and is useful as a sealing resin for electrical and electronic components. The present invention relates to polyester resin compositions for use in polyester resins.

(Conventional technology) Currently, motor coils, resistors, and capacitors.

Electrical and electronic parts such as transistors and ICs are made of water.

Resin sealing is widely practiced for the purpose of protecting against heat and various gases in the environment. When performing sealing molding, it is necessary to mold at a low pressure, since applying high pressure during molding may deform or damage the electrical/electronic components to be sealed. Furthermore, after sealing, excellent water resistance and heat resistance are required to protect electrical and electronic components from environments such as water and heat.

From this point of view, epoxy resins are now widely used as sealing resins, and transfer molding is mainly used as the molding method, and the pressure during molding (transfer pressure, injection pressure) is 150 kg / cn! The molding is performed at an extremely low pressure of 70 kir/c++ or less.

However, since epoxy resin is a thermosetting resin, it is known that there are some problems, especially in the molding process.

Namely, 1) The storage stability of the resin is poor, and the curing reaction progresses at high temperatures.

For example, it is necessary to store it at a low temperature of 20°C or lower. 2) Because it is thermosetting, in order to obtain a molded product with a long molding cycle and stable performance,
Post-curing of the molded product, for example, heat treatment at 170 to 180°C for 3 to 10 hours is required. 3) Because flakes occur during molding.

Deburring is required after molding. 4) Continuous molding with epoxy resin contaminates the mold surface, so it is necessary to periodically clean the mold.

For example, after continuous molding (usually several hundred shores), melamine resin is molded and cleaned, which is complicated. 5)
Since it is a thermosetting resin, parts of the sprue and runner other than the molded product body cannot be reused. 6) Since it is a thermosetting resin, it is difficult to automate processes such as loading one part into a mold, sealing molding, and removing the molded product. There are various problems such as: The length of the molding cycle is directly reflected in the price of the molded product, so various studies have been carried out.For example, as a method to cover the length of the molding cycle of thermosetting resin, it is possible to use a large number of molds. For example, methods have been adopted to increase the number of molded products per number of moldings by increasing the number of parts to several hundred, but this not only makes loading and unloading parts into and out of the mold complicated; Work problems have arisen as molds become larger and heavier, and solutions to these problems are strongly desired.

(Problems to be Solved by the Invention) In order to solve the problems of the above-mentioned sealing epoxy resin, the present inventors investigated the possibility of converting it into a thermoplastic resin. Thermoplastic resins have excellent storage stability before molding, and the injection molding method allows molded products to be obtained in a short molding cycle without the need for post-curing, without the occurrence of flakes, with almost no mold cleaning required, and the molding process can be automated. It has many advantages, such as being easier to use than thermosetting resins and also allowing reuse of sprues and runners.

The present inventors selected polyethylene terephthalate resin (hereinafter abbreviated as PET resin), which has excellent mechanical and thermal properties as a thermoplastic resin and is relatively inexpensive, to improve its performance as a sealing resin. We conducted a study to add the following.

PET resin has excellent mechanical properties, electrical properties, heat resistance, chemical resistance, etc., so it is not only used in many industrial products as fibers and films, but also in recent years, glass fiber etc. have been added to PET resin. It was blended. So-called reinforced PET resin has attracted attention as a resin for injection molding, and has established itself as an engineering plastic. Generally reinforced P
ET resin has excellent properties such as excellent mechanical properties and high heat distortion temperature, but in injection molding it is usually
Since it requires a high pressure of 0 to 1000 kg/cnl, it cannot be used as a sealing resin for electrical and electronic parts that are easily damaged.

Even if it is molded, there is a problem that the resulting molded product has extremely poor water resistance and cannot be put to practical use.

The present invention solves these conventional problems, and its purpose is to improve low-pressure injection moldability without impairing the excellent mechanical, thermal, and electrical properties of PET resin. It provides excellent fluidity within the mold and improves water resistance, which is a drawback of PET resin. An object of the present invention is to provide a PET resin composition useful as a sealing resin.

(Means for Solving the Problems) As a result of intensive studies to solve these problems, the present inventors added a crystal nucleating agent and an ester to a polyester in which at least 80 mol% of the repeating units are ethylene terephthalate. It was discovered that the above objective could be achieved by blending a polyester plasticizer and a polyester terminal capping agent.2
We have arrived at the present invention.

That is, the present invention provides (A) at least 80 repeating units.
A polyester component consisting of a polyester whose mole% is ethylene terephthalate, (B) a polyester component (A
) At least 0.05 parts by weight of a crystal nucleating agent per 100 parts by weight, (C) an ester plasticizer of 0.3 to 10 parts by weight per 100 parts by weight of the polyester component (A), and (D) This is a polyester resin composition for sealing, which contains a terminal blocking agent in an amount of 0.5 to 5 times equivalent to the carboxyl group of the polyester component (A).

The polyester resin composition for sealing of the present invention includes:

A fibrous reinforcing material or an inorganic filler may be added as required.

Next, one aspect of the present invention will be explained in detail.

At least 80 of the repeating units used in the invention
A polyester having a mole percent of ethylene terephthalate means polyethylene terephthalate or at least 8
It is a polyethylene terephthalate copolymer having 0 mol % of ethylene terephthalate repeating units, and they can also be used as a mixture. There are 9 different acid components as copolymerization components of polyethylene terephthalate copolymer.

Glycol components can be used.

For example, the acid component includes isophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylmethane dicarboxylic acid, diphenylsulfone dicarboxylic acid, p-(2-hydroxyethoxy)benzoic acid, 5-
Sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecane-1,12-dicarboxylic acid, tetradecane-1,14-dicarboxylic acid, hexadecane-1,16-dicarboxylic acid, octadecane-Li2-
dicarboxylic acid or 6-ethyl-hexadecane-1,
Examples include 16-dicarboxylic acid.

Examples of the glycol component include polyalkylene glycols such as propylene glycol, diethylene glycol, butylene gelylcol, pentyl glycol, neopentyl glycol, hexamethylene glycol, polyethylene glycol, and polytetramethylene glycol. Moreover, these acid components and glycol components can also be used in combination. and.

To impart high fluidity, use octadecane-1°
- A polyethylene terephthalate copolymer obtained by copolymerizing a higher dibasic acid such as dicarboxylic acid or polyethylene glycol 2 polytetramethylene glycol is desirable.

What is the carboxyl group content of the polyester component?

It is preferably about 3 to 80 mol eg/Ton.

In addition, the molecular weight of the polyester component is 0.0 in intrinsic viscosity (measured using a 6:4 (weight ratio) mixed solvent of phenol/tetrachloroethane at a concentration of 0.5 gr/d! and a temperature of 20°C). It is preferably 8 or less, particularly 0.7 or less. Moreover, the lower limit may be any value as long as the polyester resin composition for sealing maintains mechanical strength.

The crystal nucleating agent used in the present invention may be either an inorganic crystal nucleating agent or an organic crystal nucleating agent, or a mixture thereof may be used.

Specific examples of inorganic crystal nucleating agents include carbon blank, silica, calcium carbonate, synthetic silicic acid and silicates, zinc white, and hallosite clay. Kaolin, basic magnesium carbonate, mica.

Examples include talc, quartz powder, diatomaceous earth, dolomite powder, titanium oxide, zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, or calcium silicate, and one or more of these inorganic crystal nucleating agents. The above can be used, among which mica, kaolin, talc or silica are useful in the present invention.

The inorganic crystal nucleating agent used in the present invention has different effects as a crystal nucleating agent depending on its particle size, and has an average particle size of about 50 μm.
If m is exceeded, the effect will be reduced, so in example a, an inorganic crystal nucleating agent with an average particle size of 50 um or less is useful.

As the organic crystal nucleating agent used in the present invention, any organic compound having a carboxylic acid metal base can be used, but usually.

A metal salt of a higher fatty acid or an aromatic acid having 7 to 30 carbon atoms, or a polymer compound having a carboxylic acid metal salt at the terminal or side chain is used.

Specific examples of metal salts of higher fatty acids having 7 to 30 carbon atoms include heptanoic acid and pelargonic acid.

Lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, cerotic acid, montanic acid.

Alternatively, metal salts such as melisic acid are used, and examples of metal salts of aromatic acids include benzoic acid and terephthalic acid.

Examples include metal salts such as monomethyl terephthalic acid, isophthalic acid, and monomethyl ester of isophthalic acid.

In addition, examples of polymer compounds having a carboxylic acid metal salt at the terminal or side chain include 2, for example, carboxyl group-containing polyethylene obtained by oxidizing polyethylene, carboxyl group-containing polypropylene obtained by oxidizing polypropylene, ethylene, propylene, butene-1 Metals such as copolymers of olefins and (meth)acrylic acid, copolymers of olefins and maleic anhydride, copolymers of styrene and (meth)acrylic acid, or copolymers of styrene and maleic anhydride, etc. A specific example is a metal salt of a copolymer of olefin and (meth)acrylic acid, or a copolymer of styrene and (meth)acrylic acid.

As the metal forming the carboxylic acid metal salt, alkaline earth metals, alkali metals, etc. are usually used, and the alkali metals have excellent effects as crystal nucleating agents, and among them, sodium and potassium are useful.

The blending amount of the crystal nucleating agent in the polyester resin composition for sealing of the present invention varies depending on the type of crystal nucleating agent, but at least one of an inorganic crystal nucleating agent and an organic crystal nucleating agent is added to 100 parts by weight of the polyester component. , at least 0.0
5 parts by weight.

When using an inorganic crystal nucleating agent, polyester component 1
Up to about 300 parts by weight can be added to 00 parts by weight, but if the amount is large.

Effects such as improving the physical properties and thermal conductivity of the polyester resin composition for sealing, reducing the coefficient of thermal expansion, and preventing sink marks on molded products can also be expected.

When an organic crystal nucleating agent is used, it can be blended in an amount up to about 10 parts by weight per 100 parts by weight of the polyester component, preferably 0.1 to 5 parts by weight, particularly 0.1 to 5 parts by weight.
1 to 3 parts by weight is desirable.

As the ester plasticizer used in the present invention, one of various compounds can be used, and among them, ester compounds represented by the following general formulas (1), (II), and (H[) are suitable for crystallization of PET. Useful as an accelerator and flow improver. Moreover, these ester plasticizers can also be used in combination.

Rz (OCHzCHz)IllOCR+-CO(CH
zCHzO)l, R5 (however, Ro is an alkylene group, R2, R3 is a group selected from the group consisting of an alkyl group, a Hensyl group, and an aromatic substituted benzyl group)
Z+ R2 are the same or different groups, m and n are 1
is an integer greater than or equal to ) (However, X is a direct bond or a group selected from the group consisting of al derivatives, R4 and R5 are the same or different groups, and R6 and Rt are hydrogen.

A group selected from the group consisting of an alkyl group and a halogen group, and R and R are the same or different groups.

m and n are integers of 1 or more. ) (However, Re and RQ are hydrogen, groups selected from the group consisting of alkyl groups, phenyl groups, benzyl groups, and derivatives thereof, and R11 and R9 are the same or different groups,
R3゜ is a group selected from the group consisting of phenyl group, Hensyl group and derivatives thereof, R8 is a group selected from the group consisting of hydrogen, alkyl group and the group defined by RIG, and n is 4 or more. is an integer. ) The blending amount of the ester plasticizer in the polyester resin composition for sealing of the present invention is 0.3 to 10 parts by weight, preferably 2 to 10 parts by weight, more preferably 3 to 10 parts by weight, based on 100 parts by weight of the polyester component. 7 parts by weight. If the blending amount of the ester plasticizer is less than 0.3 parts by weight per 100 parts by weight of the polyester component, the effect as a crystallization accelerator and the effect of improving fluidity will be small, and the molded product will have excellent surface properties. On the other hand, if the amount is more than 10 parts by weight, other performances such as thermal properties will deteriorate.

The terminal blocking agent used in the present invention is a compound having one or two functional groups that react with the carboxyl group of the polyester component. Examples of such end-capping agents include, for example,
Examples include compounds having an epoxy group or an isocyanate group, oxazolines, oxacilones, carbodiimides, carbonate compounds, or diazo compounds. Such end-capping agents can be used even if mixed.

Specific examples of epoxy compounds include N-glycidyl phthalimide, N-glycidyl tetrahydrophthalimide,
phenylglycidyl ether, p-tert-butylphenylglycidyl ether, dibromphenylglycidyl ether, neohexene oxide, 1-decene oxide, 1-tetradecene oxide, 1-hexadecene oxide or l-octadecene oxide, etc. Examples of functional epoxy compounds include 1. Examples of difunctional epoxy compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and neopentyl glycidyl ether. glycidyl ether,
Various glycidyl ether compounds such as 4-butanediol diglycidyl ether, 1,6-hexanesiol diglycidyl ether, dibromneopentyl glycol diglycidyl ether, and bisphenol A diglycidyl ether, as well as adipic acid, azelaic acid, and sebacic acid. , dodecane-1,12-dicarboxylic acid, tetradecane-1,14-dicarboxylic acid, octadecane-1,18
-dicarboxylic acid, 6-ethylhexadecane-1,16-
In addition to various diglycidyl ester compounds such as dicarboxylic acid, phthalic acid, or diphenyl ether dicarboxylic acid, N
, N'-diglycidylpyromelliticimide, N, N'
Specific examples include -diglycidylaniline and N,N'-diglycidylerbital.

Examples of the compound having an isocyanate group include toluene diisocyanate and diphenylmethane diisocyanate. Examples of the oxazoline compound include bisoxazoline.

In addition to p- and m-phenylene oxazolines, various carbodiimide compounds such as ethylene carbonate, diphenylcarposiimide, and di(2,6-ituprobylphenyl)carbodiimide can be listed. In order to promote the reaction between these compounds and the terminal capping agent, various catalysts can be added. Among these end-capping agents, polypropylene glycol, diglycidyl ether, or octadecane-1,18-dicarboxylic acid diglycidyl ester, in which the repeating units of propylene glycol are about 1 to 10, are particularly effective in improving the water resistance of the composition without impairing fluidity. , which is desirable because it can improve heat resistance.

The blending amount of the end-blocking agent in the polyester resin composition for sealing of the present invention varies depending on the type of end-blocking agent used, but the amount is 0.00% relative to the carboxyl group of the polyester component.
5 to 5 times equivalent is preferred. If the blending ratio is less than 0.5 times equivalent, the effect of blocking the terminal carboxyl group will be reduced,
The water resistance improvement effect of polyester decreases. On the other hand, if the amount is more than 5 times equivalent, the water resistance improving effect will be improved, but the operational stability in the kneading process and molding process of the 9 composition will be lowered, and other performance aspects will be lowered.

The polyester resin composition for sealing of the present invention includes:

If necessary, a fibrous reinforcing material or an inorganic filler may be added alone or in combination.

Specific examples of such fibrous reinforcing materials include glass fibers, carbon fibers, aromatic polyamide fibers, silicon carbide fibers, and titanate fibers, but glass fibers are usually used. In addition, there are no particular restrictions on the diameter and length of the various fibers, but if the fiber length is too long, it will be difficult to mix and disperse uniformly with the polyester component, crystal nucleating agent, and ester plasticizer, and vice versa. If the fiber length is too short, the effect as a reinforcing material will be insufficient.2 Usually, fibers with a length of 0.1 to 10 mm are used. In particular, when the fibrous reinforcing material is glass fiber, The length is preferably 0.1 to 71 layers, more preferably 0.3 to 4 layers. In addition, the purpose of the fibrous reinforcing material is to improve the interfacial adhesion with polyester and increase the reinforcing effect.

If necessary, glass fibers treated with various compounds can be used, but when using glass fiber as a fibrous reinforcing material, various surface treatment agents such as vinyltriethoxysilane, γ-methacryloxysilane, etc. Propylmethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, T-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxylane, T-chloropropylmethoxysilane, T-mercapto Those treated with a silane treatment agent such as propyltrimethoxysilane or a chromium treatment agent such as methacrylate chromic chloride are used.

In addition, as an inorganic filler that may be added to the polyester resin composition for sealing of the present invention as needed.

Examples include silicon carbide, silicon nitride, helium oxide, boron nitride, and magnesium oxide. Such an inorganic filler not only improves the physical properties of the polyester resin composition for sealing, but also brings about effects such as improving thermal conductivity, reducing the coefficient of thermal expansion, and preventing sink marks on molded products.

In the present invention, the amount of the fibrous reinforcing material or inorganic filler blended as necessary varies depending on the required performance of the use of the polyester resin composition for sealing, but It is desirable that the amount is 70% by weight or less. When the blending amount increases, not only does it become difficult to mix and disperse uniformly, but also the fluidity during molding of one composition decreases.

The polyester resin composition for soil use of the present invention includes:

In addition, antioxidants and ultraviolet absorbers as necessary.

Various inorganic or organic compounds such as colorants, mold release agents, fillers, etc. can be blended.

The polyester resin composition for soil use of the present invention can be manufactured by mixing in various ways, and the manufacturing method is not particularly limited, but usually by adding each component or additive to the polyester component. It is manufactured by mixing the ingredients using an extruder or a niegu.

(Example) Next, the present invention will be specifically described with reference to Examples and Comparative Examples.

Note that "parts" shown in Examples and Comparative Examples indicate "parts by weight."

Examples 1-10. Comparative Examples 1 to 5 Polyethylene terephthalate (abbreviated as PET) and polyethylene terephthalate copolymer (abbreviated as copolymerized PET) shown in Table 1 were produced according to a conventional method.

However, the intrinsic viscosity is phenol/tetrachloroethane=
6/4 (weight ratio) in solvent, concentration 0.5 gr/d
i is a value measured at a temperature of 20°C. In addition, the terminal carboxyl group concentration of the polyester component ([-COO
H')) was measured by a conventional method.

Next, various crystal nucleating agents, ester plasticizers, terminal blocking agents, and glass fibers (manufactured by Asahi Fiberglass, 3-layer chopped strand, product number m) were added to the copolymerized PET without PET.
429) and an inorganic filler and kneaded with a twin-screw extruder to create various pellets shown in Table 2. After drying,
Cylinder temperature 250-260-270°C9 Mold temperature 100°C.

The spiral flow length (c, n) was measured at an injection pressure of 150 kg/ci and a cooling time of 15 seconds to examine the fluidity.

Similarly, cylinder temperature 250-260-270℃, mold temperature 100℃, injection pressure 400-600kg/
clll, injection holding time 10 seconds, cooling time 20 seconds, V4
:>×+A4>×54> A cylindrical test piece was molded.

Bending strength 1 Flexural modulus, Heat deformation temperature () Abbreviated as IDT.

A load of 18.56 kg/cffl) was measured. Also,
A disk with a thickness of 4 mm and a diameter of 4 mm was molded under the same molding conditions.

Volume resistivity was measured. In addition, in order to evaluate water resistance, we examined the change in bending strength after immersing the test piece in 80°C hot water for 20 days and the pressure Kutsuker test (PCT).
It is abbreviated as. The test conditions were to leave the sample in water vapor at 121°C and 2 atm for 24 hours. ) After measuring the bending strength and volume, the resistivity was measured. The results are summarized in Table 3.

From this, the following was clarified. 1) Adding a specific ester plasticizer to PET improves fluidity.

2) Fluidity improves when copolymerized PET is blended.

3) Adding a specific end-blocking agent improves water resistance and increases strength retention after a water resistance test. 4) Adding an ester plasticizer improves the heat distortion temperature.

Although the PETO heat distortion temperature depends on the crystallinity of PIET, it was possible to mold it by adding a specific ester plasticizer even under conditions such as a mold temperature of 100°C, which is difficult for ordinary PET to crystallize. this is.

It is considered that this is because the crystallization rate increased, and as a result, crystallization proceeded even at a mold temperature of 100° C., and the heat distortion temperature became high.

Example 11. Comparative example 6 The pellets shown in Example 1 and Comparative Example 1.

After drying with hot air at 130°C for 5 hours, low pressure injection molding 1
A mold for sealing a capacitor was placed in JTO3-25V, and a molding test was conducted at a cylinder temperature of 250-270-280°C, a mold temperature of 80°C, an injection time of 20 seconds, and a cooling time of 30 seconds. For the pellets of Example 1, the -second injection pressure (before the gate part) was 13 (Hg/cal), and the secondary injection pressure (before the gate part) was 13 (Hg/cal).
The resin was filled into the mold at a rate of 30 kg/cd (after the gate part), but for the pellets of Comparative Example 1, the primary injection pressure was 300 kg/cd.
kg/cot, and the secondary injection pressure was 200 kg/cIIt, but the filling was insufficient.

(Effects of the Invention) The polyester resin composition for sealing of the present invention has superior fluidity compared to ordinary polyester resin compositions, so low-pressure injection molding is possible, and it has improved water resistance and Because it has heat resistance.

It is useful as a sealing resin for electrical and electronic parts that are easily damaged or deformed.

Claims (1)

[Claims] (1) (A) a polyester component consisting of a polyester in which at least 80 mol% of repeating units are ethylene terephthalate; (B) based on 100 parts by weight of the polyester component (A);
at least 0.05 parts by weight of a crystal nucleating agent, (C) based on 100 parts by weight of the polyester component (A),
A polyester resin composition for sealing comprising 0.3 to 10 parts by weight of an ester plasticizer and (D) an end capping agent in an amount of 0.5 to 5 times equivalent to the carboxyl group of the polyester component (A).