JP2000336255A - Polybutylene terephthalate resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition showing good water repellency and surface appearance by mixing a specific amount of a modified silicone oil having a plurality of hydroxy groups and a boric acid compound with polybutylene terephthalate. SOLUTION: This composition contains 100 pts.wt. of polybutylene terephthalate (A) having intrinsic viscosity (in o-chlorophenol at 25 deg.C) of 0.55 to 1.0 dl/g and concentration of a carboxylic end group of not more than 50 meq/kg, a modified silicone oil having not less than 2 hydroxy groups (B), 0.001 to 2 pts.wt. of a boric acid compound (C) such as ortho boric acid or the like, the weight ratio of the component C to the component B being 0.001 to 0.1. The component B includes a silicone oil having alcoholic hydroxy groups at both ends of the molecule or silanol groups at both ends of the molecule and preferably has viscosity of not more than 200,000 cSt (at 25 deg.C) (wherein n is an integer of not less than 0; R is methyl and some of R groups may be an alkyl, phenol or the like; and Ra is an alkyl or phenyl).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition comprising a polybutylene terephthalate resin and a modified silicone oil having a hydroxyl group and a boric acid compound, and a water repellency obtained by molding the composition. It relates to a molded part having excellent appearance.

[0002]

2. Description of the Related Art Polybutylene terephthalate resin is a highly crystalline polymer,
It is a material with excellent mechanical properties. However, since it has a polyester structure, it is easily susceptible to hydrolysis, and the decomposition proceeds particularly under high temperature and high humidity, making it unsuitable for parts around water. On the other hand, water-repellent liquid substances such as silicone oil impart water repellency by being added to and blended with a resin, and are also excellent in antifouling properties. It has been heavily used. However, water-repellent liquid substances such as silicone oil are compatible with polybutylene terephthalate resin,
Since the affinity is extremely poor, it is extremely difficult to mix the compound, and this involves the generation of gas during kneading. Even if such a composition can be prepared, when it is molded, the liquid substance easily bleeds to the surface of the resin, and its lubricating action causes slippage between the resins or between the resin and the screw. Poor penetration into the machine, poor plasticization, and the like occur, and in severe cases, processing becomes impossible. The present invention
In view of the above problems, a polybutylene terephthalate resin composition having no gas generation during melt-kneading, no surface separation during molding, and excellent hydrolysis resistance, water repellency, and excellent appearance The purpose is to provide.

[0003]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that by blending a modified silicone oil having a hydroxyl group and a boric acid compound with a polybutylene terephthalate resin, good repellency is obtained. It has been found that a resin composition having an aqueous surface appearance can be obtained, and the present invention has been achieved. That is, the present invention relates to (A) 100 to 100 parts by weight of a polybutylene terephthalate resin, (B) 0.05 to 20 parts by weight of a modified silicone oil having at least two hydroxyl groups, and (C) 0.001 to 2 parts by weight of a boric acid compound. The present invention relates to a polybutylene terephthalate resin composition that is blended.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION The constituents of the composition of the present invention will be described below. First, the polybutylene terephthalate resin (A) of the present invention is a polybutylene terephthalate obtained by polycondensing terephthalic acid or an ester-forming derivative thereof with an alkylene glycol having 4 carbon atoms or an ester-forming derivative thereof. In addition, polybutylene terephthalate may be a copolymer containing 70% by weight or more per se. As dibasic acid components other than terephthalic acid and its lower alcohol esters, aliphatic and aromatic polybasic acids such as isophthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, and succinic acid or ester-forming derivatives thereof And the like, as a glycol component other than 1,4-butanediol, a normal alkylene glycol such as ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol,
Hexamethylene glycol, neopentyl glycol,
Cyclohexanedimethanol, lower alkylene glycols such as 1,3-octanediol, bisphenol A, aromatic alcohols such as 4,4'-dihydroxybiphenyl, ethylene oxide 2 mol adduct of bisphenol A, propylene oxide 3 mol of bisphenol A Alkylene oxide adduct alcohols such as adducts,
Examples thereof include polyhydroxy compounds such as glycerin and pentaerythritol, and ester-forming derivatives thereof.
In the present invention, any polybutylene terephthalate produced by polycondensation using the above compound as a monomer component can be used as the component (A) of the present invention, and used alone or as a mixture of two or more. Further, the intrinsic viscosity of the polybutylene terephthalate resin used is not particularly limited, but is 0.3 to 1.5 dl / g at a concentration of 0.5% by weight and 25 ° C. using o-chlorophenol as a solvent.
Are preferred, more preferably 0.55 to 1.2 dl / g, especially 0.55
~ 1.0 dl / g is preferred. Further, as a polybutylene terephthalate resin, the terminal carboxyl group concentration is 50%.
When using meq / kg or less, especially 30 meq / kg or less,
Since the hydrolysis resistance of the resin can be improved and the mechanical properties especially under high temperature and high humidity can be maintained for a long time,
Particularly preferred. The terminal carboxyl group concentration is measured by dissolving a ground material of polybutylene terephthalate resin in benzyl alcohol at 215 ° C. for 10 minutes, and titrating with a 0.01N aqueous sodium hydroxide solution.

The modified silicone oil (B) having a hydroxyl group used as the component (B) in the present invention includes a silicone oil having an alcoholic hydroxyl group at both molecular chain terminals represented by the following general formula (1): And the following general formula
Silicone oils having silanol groups at both ends of the molecular chain represented by (2) are mentioned, and one or more of them are used.

[0006]

Embedded image

(Where n is an integer of 0 or more and R is a methyl group, some of which may be an alkyl group, a phenyl group, a halogenated alkyl group, a halogenated phenyl group or the like. _Ra is an alkyl group or a phenyl group.) The modified silicone oil having at least two hydroxyl groups (hereinafter simply referred to as modified silicone oil) used in the present invention may be a commercially available product, and may have a viscosity. Although there is no particular limitation, those which are liquid at room temperature are preferred, and 200,000 cSt (25 ° C.) or less, particularly 10,000
It is preferably less than cSt. The reason will be described in detail later, but it is presumed that the reaction between the hydroxyl group and the boric acid compound is greatly involved in the improvement of the moldability.If the molecular weight becomes too large, the number of reaction points with the boric acid compound decreases, It is considered that the effect of improving the moldability does not significantly appear. The amount of the modified silicone oil (B) is 0.05 to 20 parts by weight, particularly preferably 0.5 to 5 parts by weight, per 100 parts by weight of the polybutylene terephthalate resin (A). The blending amount is 0.
If the amount is less than 05 parts by weight, the effect of improving moldability is not sufficiently exhibited,
Further, when the amount is more than 20 parts by weight, the extrudability and the moldability are extremely deteriorated.

The boric acid compound (C) used in the present invention includes orthoboric acid, metaboric acid, tetraboric acid and diboron trioxide, and commercially available products can be used. The amount of the boric acid compound is 0.001 to 2 parts by weight, preferably 0.005 to 1 part by weight, particularly preferably 0.1 to 2 parts by weight.
01 to 0.5 parts by weight. If the amount is less than 0.001 part by weight, the desired effect cannot be obtained. If the amount exceeds 2 parts by weight, thermal stability becomes a problem.

Although the mechanism of action for improving the moldability of the polybutylene terephthalate resin composition according to the present invention is not necessarily clear, the present inventors speculate that the modified silicone oil ( It is considered that the biteability of the screw of the molding machine is improved because B) reacts with the boric acid compound (C) to form a gel-like substance. In addition, since this gel-like substance plays a role of retaining unreacted modified silicone oil, spotting of the unreacted silicone oil retained in the gel-like substance is appropriately controlled, so that it can be used during molding. It is presumed that no surface peeling occurs and the excellent water repellent effect inherent to the silicone oil itself is maintained for a long period of time.

[0010] Further, by regulating the addition ratio of (B) the modified silicone oil and (C) the boric acid compound, the reaction efficiency can be further increased, and the extrudability, moldability, water repellency and the like can be improved. When the weight ratio of the (C) boric acid compound to the (B) modified silicone oil is in the range of 0.001 to 0.1, especially 0.003 to 0.05, the reaction efficiency is particularly high. If the amount is too small, a sufficient reaction between the modified silicone oil and the boric acid compound cannot be achieved, the amount of unreacted silicone oil increases, poor penetration during melt-kneading, deterioration in moldability, etc., and an excessive amount Because of the presence of a large amount of unreacted boric acid compounds, the acidity in the resin increases, causing the resin to decompose during heating and melting, and at high temperatures and high humidity. It is also a preferable method for improving the moldability that the modified silicone oil (B) and the boric acid compound (C) described below are reacted in advance and the product is mixed with a polybutylene terephthalate resin. In the present invention, a filler is used as needed. Such a filler is preferably blended in order to obtain excellent properties such as mechanical strength, heat resistance, dimensional stability, and electrical properties, and is particularly effective for increasing rigidity. For this purpose, a fibrous, powdery or plate-like filler is used depending on the purpose. Examples of the fibrous filler include glass fiber, asbestos fiber, carbon fiber, silica fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium, Examples include fibrous materials of metals such as copper and brass.
In addition, a high melting point organic fibrous substance such as polyamide, fluororesin, and acrylic resin can also be used. Examples of the particulate filler include carbon black, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate,
Silicates such as kaolin, talc, clay, diatomaceous earth, wollastonite, oxides of metals such as iron oxide, titanium oxide and alumina, carbonates of metals such as calcium carbonate and magnesium carbonate, calcium sulfate, barium sulfate And other metal powders such as silicon carbide, silicon nitride, silicon nitride, boron nitride, and the like. Examples of the plate-like inorganic filler include mica, glass flake, various metal foils, and the like. The type of the filler is not particularly limited, and one or more fillers may be added, but it is particularly preferable to use potassium titanate fiber, mica, talc, and wollastonite. Further, in the composition of the present invention, a known substance generally added to a thermoplastic resin or the like can be added and used in order to impart desired properties according to the purpose. For example, antioxidants, ultraviolet absorbers, stabilizers such as light stabilizers, flame retardants, flame retardant aids, antistatic agents, lubricants, mold release agents,
Any of coloring agents such as dyes and pigments, plasticizers, and the like can be blended. In particular, the addition of an antioxidant for improving heat resistance is effective.

[0011] The polybutylene terephthalate resin composition of the present invention can be easily prepared by equipment and a method generally used as a conventional resin composition preparation method. For example, (1) a predetermined amount of components constituting the composition of the present invention are mixed at once and melt-kneaded by a single-screw or twin-screw extruder to obtain pellets of a desired composition. (2) Two raw material inlets are provided. With a single-screw or twin-screw extruder having the above, a resin, a stabilizer, a pigment component, etc. are charged and melt-kneaded from a first input port, and then an inorganic filler is charged from a second material input port, and melt-kneaded. To obtain pellets having a desired composition. The method for molding the resin composition of the present invention is not particularly limited, such as injection molding, extrusion molding, blow molding, etc., but injection molding is particularly preferred.

The molded article obtained according to the present invention is JIS
By measuring the glossiness according to the Z8741 specular glossiness measuring method, it has a 60 ° specular glossiness of 90% or more, more preferably 100% or more. Further, the glossiness of 100% or more can be maintained even after 200 hours under moist heat. In general, even under high temperature and high humidity where the polybutylene terephthalate resin is considered to be degraded and deteriorated to lower the gloss, the method of the present invention does not show a decrease in the gloss. The water contact angle of the molded product obtained in the same manner was 85
A component having an angle of ゜ or more, more preferably 90 ° or more is preferably used as an external part. According to the present invention, a component having this property can be obtained. As described above, the molded article obtained by the present invention has good water repellency and retains surface gloss for a long time even under high temperature and high humidity, so that it can be used for kitchen parts, washing machine parts, washing tools, bath and bath parts. It is suitable for sanitary parts and appearance parts such as water-supply parts typified by these peripheral devices.

[0013]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Examples 1 to 9, Comparative Examples 1 to 11 Intrinsic viscosity 0.82 dl / g, terminal carboxyl group concentration of 45 meq
/ Kg of polybutylene terephthalate resin, the modified silicone oil and the boric acid compound were mixed in the amounts shown in Table 1, and then melt-kneaded with a twin-screw extruder to prepare a pellet-shaped composition. Next, a test piece was molded from the pellet-shaped composition using an injection molding machine, and the physical properties shown below were measured. Table 1 shows the results. For comparison, as shown in Table 2, a composition using a silicone oil having no hydroxyl group represented by polydimethylsiloxane, a composition containing only a modified silicone oil, and a composition containing only a boric acid compound were similarly used. It was prepared and evaluated. Table 2 shows the results. The evaluation items and evaluation methods are as follows. (Surface peeling during molding) Using a screw-type injection molding machine,
A flat plate having a thickness of 1 mm was formed at a screw temperature of 250 ° C., the injection speed was increased to 1, 2, and 4 m / min, and the occurrence of surface peeling was confirmed. If no peeling occurred, it was evaluated as “absent”, and if peeling occurred, it was evaluated as “present”. [Water repellency] Using a screw-type injection molding machine, mold a plate with a thickness of 3 mm at a screw temperature of 250 ° C and a mold temperature of 70 ° C, wipe it off with ethanol without damaging the plate surface, Contact angle measuring instrument FACE C
Using AZ, the water contact angle was measured at room temperature and 25 ° C. (Surface appearance under wet heat) Using a screw type injection molding machine,
A plate with a thickness of 3 mm is formed at a screw temperature of 250 ° C and a mold temperature of 70 ° C, and is put into a constant temperature and humidity chamber at 80 ° C and a humidity of 95%. It was measured by a portable gloss meter HG246 manufactured by Co., Ltd.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

As described above, the polybutylene terephthalate resin composition of the present invention is capable of producing gas at the time of melt-kneading by adding the modified silicone oil and the boric acid compound to the polybutylene terephthalate resin and mixing and kneading. It is possible to provide a molded article which is not seen, does not undergo surface separation during molding, and has good water repellency, hydrolysis resistance and appearance.

Claims (7)

[Claims] (1) Polybutylene terephthalate resin (A) 100
A polybutylene terephthalate resin composition comprising (B) 0.05 to 20 parts by weight of a modified silicone oil having at least two hydroxyl groups, and (C) 0.001 to 2 parts by weight of a boric acid compound. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the weight ratio of the (C) boric acid compound to the (B) modified silicone oil is in the range of 0.001 to 0.1. 3. The polybutylene terephthalate resin composition according to claim 1, wherein (A) the polybutylene terephthalate resin has an intrinsic viscosity of 0.55 to 1.2 dl / g. 4. The polybutylene terephthalate resin composition according to claim 1, wherein the modified silicone oil (B) is a silicone oil having an alcoholic hydroxyl group at both molecular chain terminals. 5. The polybutylene terephthalate resin composition according to claim 1, wherein the modified silicone oil (B) is a silicone oil having silanol groups at both molecular chain terminals. 6. The polybutylene terephthalate resin composition according to claim 1, wherein the modified silicone oil (B) is a liquid at room temperature. 7. An external part made of a polybutylene terephthalate resin obtained by molding the polybutylene terephthalate resin composition according to any one of claims 1 to 6.