JPH069865A - Resin composition for grip of tooth brush - Google Patents

Abstract

PURPOSE:To provide a resin composition excellent in design, chemical resistance, fatigue characteristics, flowability, etc., by compounding the composition of a specific aromatic polycarbonate resin and specified polyethylene terephthalate resin with two kinds of specific compounds in small amounts, respectively. CONSTITUTION:The resin composition having an elastic modulus of 20000-27000 kgf/cm<2> comprises 100 pts.wt. of a resin composition comprising (A) 50-90wt.% of an aromatic polycarbonate resin having a viscosity-average mol.wt. of 20000-30000 and (B) 50-10wt.% of polyethylene terephthalate resin having an intrinsic viscosity of 0.6-1, (C) 0.001-1 pt.wt. of a diphosphite compound of the formula (R1, R2 are H, alkyl, etc.), and (D) 0.001-2 pts.wt. of on ester of a 12-30C aliphatic saturated monobasic carboxylic acid with a <=30C aliphatic saturated alcohol (e.g. beeswax, montanic acid ethylene glycol ester).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition suitable for a handle of a toothbrush. More specifically, chemical resistance, fatigue characteristics,
The present invention relates to a resin composition for toothbrushes, which has excellent rigidity, fluidity and releasability.

[0002]

2. Description of the Related Art Generally, a polypropylene resin is widely used as a material for a handle of a toothbrush because of its chemical resistance. However, since polypropylene resin has low rigidity, it requires a considerable thickness and has a drawback that it is uncomfortable to use. In order to eliminate this drawback and enhance the usability of the toothbrush, use of a thermoplastic polyester resin such as a polyethylene terephthalate resin having high rigidity or an aromatic polycarbonate resin has been studied.

Although thermoplastic polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin are excellent in rigidity and chemical resistance, when fine scratches such as tooth contact scratches during brushing occur, the fine scratches are generated. It has a drawback that it is easily broken due to the stress concentration, that is, the notch sensitivity is high. Further, since the thermoplastic polyester resin has a high molding temperature and a low solidification temperature, that is, a glass transition temperature, it has a drawback that the molding cycle becomes long and the cost becomes high.

On the other hand, aromatic polycarbonate resins are excellent in rigidity and fatigue characteristics, but have a problem in chemical resistance. Toothpastes are apt to cause microcracks and brush bristles are easily removed during toothbrushing. It has drawbacks, and further, it has poor melt fluidity and is difficult to mold.

In order to utilize the preferable characteristics of each of the aromatic polycarbonate resin and the polyethylene terephthalate resin, it has been attempted to mix them, but when they are melt-kneaded, they have chemical resistance and fatigue characteristics because they are kneaded at high temperature. ,
There has been a problem that an exchange reaction between resins, which adversely affects mechanical properties, proceeds. Also, when molding the handle of the toothbrush, especially when molding the handle of a thin toothbrush with a good feeling of use,
It has a drawback that it is easily affected by the stress at the time of mold release and the fatigue characteristics are deteriorated by the residual stress.

Therefore, a resin composition for a handle of a toothbrush, which has excellent design properties, chemical resistance, fatigue properties, mechanical properties such as rigidity, fluidity, and releasability, is desired.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a resin composition for a handle of a toothbrush, which has excellent design properties, chemical resistance, fatigue properties, mechanical properties such as rigidity, fluidity and releasability. To aim.

As a result of intensive studies to achieve the above object, the present inventor found that a specific diphosphite compound and an aliphatic saturated monovalent compound were added to a composition of a specific aromatic polycarbonate resin and a specific polyethylene terephthalate resin. The inventors have found that the target resin composition for a toothbrush handle can be obtained by adding small amounts of carboxylic acid and aliphatic saturated alcohol ester, respectively, and arrived at the present invention.

[0009]

According to the present invention, (A) 50 to 90% by weight of an aromatic polycarbonate resin having a viscosity average molecular weight of 20,000 to 30,000 and (B) an intrinsic viscosity of 0.
Polyethylene terephthalate resin 50 of 6 to 1.0
To 100 parts by weight of a resin composition consisting of 10 to 10% by weight, (C)
Diphosphite compound represented by the following formula [1] 0.00
1 to 1 parts by weight and (D) an elasticity obtained by blending 0.001 to 2 parts by weight of an ester of an aliphatic saturated monovalent carboxylic acid having 12 to 30 carbon atoms and an aliphatic saturated alcohol having 30 or less carbon atoms The present invention relates to a resin composition for a toothbrush handle having a rate of 20000 to 27000 kgf / cm ² .

[0010]

[Chemical 2]

[Wherein R ₁ and R ₂ are a hydrogen atom, an alkyl group, an arylalkyl group, an aryl group, an alkylaryl group, a 2- (4-oxyphenyl) propyl-substituted aryl group or a cycloalkyl group, and R ₁ And R ₂ may be the same or different. The polycarbonate resin used in the present invention is an aromatic polycarbonate resin having a viscosity average molecular weight of 20,000 to 30,000, preferably 22,000 to 27,000, which is derived from a dihydric phenol, and usually a dihydric phenol and a carbonate precursor are subjected to a solution method or It is manufactured by reacting by a melting method. The dihydric phenol used here is 2,2-bis (4-hydroxyphenyl) propane [commonly called bisphenol A].
However, some or all of them may be replaced with other dihydric phenol. Other dihydric phenols include, for example, bis (4-hydroxyphenyl) methane, 2,2-
Examples thereof include bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane and bis (4-hydroxyphenyl) sulfone. Examples of the carbonate precursor include carbonyl halide, carbonyl ester, haloformate and the like, and specific examples thereof include phosgene, diphenyl carbonate, dihaloformate of dihydric phenol and a mixture thereof. In producing the aromatic polycarbonate resin, an appropriate molecular weight modifier, branching agent, catalyst for accelerating the reaction and the like can be used. The molecular weight of the aromatic polycarbonate resin is 20,000 to 30,000, preferably 220 in terms of viscosity average molecular weight.
It is 00-27,000. Viscosity average molecular weight is 20,000
If it is less than the following, the fatigue property will be deteriorated, and if it exceeds 30,000, the fluidity will be deteriorated.

The polyethylene terephthalate resin used in the present invention is a polymer obtained by subjecting terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative to a condensation reaction as main raw materials,
A copolymer in which 30 mol% or less of terephthalic acid is replaced with another dicarboxylic acid, or 30 mol% or less of ethylene glycol is replaced with another aliphatic diol or alicyclic diol may be used. Examples of the dicarboxylic acid used in such a copolymer include isophthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid and the like. Examples of the diol include polymethylene-α, ω-diols,
Examples include neopentyl glycol and diethylene glycol. The polyethylene terephthalate resin used in the present invention has an intrinsic viscosity of 0.6 to 1.0, preferably 0.65 to 0.95, measured at 25 ° C. with o-chlorophenol as a solvent. If the intrinsic viscosity is less than 0.6, the notch sensitivity will be high, and if it exceeds 1.0, the moldability will be deteriorated.

The mixing ratio of the aromatic polycarbonate resin and the polyethylene terephthalate resin is 50 in the former case.
˜90% by weight, the latter 50 to 10% by weight. If the mixing ratio of the polyethylene terephthalate resin is more than 50% by weight, notch sensitivity becomes high and the fatigue characteristics deteriorate, and if it is less than 10% by weight, chemical resistance and rigidity become insufficient.

Preferred examples of the diphosphite compound represented by the above formula [1] used in the present invention include the following compounds.

[0015]

[Chemical 3]

[0016]

[Chemical 4]

[0017]

[Chemical 5]

[0018]

[Chemical 6]

[0019]

[Chemical 7]

The diphosphite compound represented by the formula [1] is added in an amount of 0.001 to 1 part by weight based on 100 parts by weight of the composition of the aromatic polycarbonate resin and the polyethylene terephthalate resin. If the amount added is less than 0.001 part by weight, the processing stability of the composition is not sufficiently improved, and if it exceeds 1 part by weight, bubbles tend to be generated in the handle of the toothbrush obtained using the composition, and Fatigue properties and chemical resistance will be adversely affected.

The ester of an aliphatic saturated monovalent carboxylic acid and an aliphatic saturated alcohol used in the present invention has 12 carbon atoms.
It is an ester or partial ester of ~ 30 aliphatic saturated monohydric carboxylic acid and an aliphatic saturated monohydric alcohol or saturated polyhydric alcohol having 30 or less carbon atoms. Many of such aliphatic esters are known as ester waxes contained in natural products such as plants, animals, insects and minerals, and for example, beeswax (a mixture containing myricyl palmitate as a main component), Examples include spalm acetyl (mixture containing cetyl palmitate as a main component), ethylene glycol ester of montanic acid, and the like.

The amount of the ester of the aliphatic saturated monovalent carboxylic acid and the aliphatic saturated alcohol added is 0.001 to 2 parts by weight based on 100 parts by weight of the composition of the aromatic polycarbonate resin and the polyethylene terephthalate resin. is there. If it is less than 0.001 part by weight, the releasing effect of the composition is insufficient, and if it exceeds 2 parts by weight, the fatigue properties are adversely affected.

The elastic modulus of the composition thus obtained is 200.
It should be between 00 kgf / cm ^{2 and} 27,000 kgf / cm ² . By having an elastic modulus in this range, the toothbrush with the best feeling of use can be obtained. That is, 20000 kgf
If it is less than / cm ^2, it becomes too soft when it is made into a toothbrush with a thin neck, and it becomes too flexible. 27,000 kgf / cm
^When it exceeds ² , the flexion becomes small and the gums are easily damaged.

The toothbrush handle resin composition of the present invention comprises a polycarbonate resin, a polyethylene terephthalate resin, a diphosphite compound and a predetermined amount of an aliphatic ester such as a tumbler, a V-type blender, a Nauter mixer, a Banbury mixer, It can be manufactured by mixing with a mixer such as a kneading roll or an extruder.

In the composition of the present invention, other additives such as a pigment, in addition to the above components, may be added within a range not impairing the object of the present invention.
You may mix | blend a dye, an antibacterial agent, etc.

[0026]

EXAMPLES The present invention will be further described with reference to the following examples. In addition, the part in an Example is a weight part and evaluation was based on the following method.

Chemical resistance: length 50 mm obtained by injection molding,
Servo pulsar EHF manufactured by Shimadzu Corporation under the conditions of 1Hz load and 4Hz in an atmosphere of 30 ° C after applying a toothpaste [Acess] manufactured by Sato Pharmaceutical Co., Ltd. on a rod-shaped test piece with a width of 5mm and a thickness of 4mm.
-Repeated flexural fatigue test by FD, and the number of times until breakage was measured. ○ those that did not break after 25,000 cycles, △ those that failed between 15,000 and less than 25,000 cycles, and 1. What was broken after less than 50,000 times was shown by x.

Fatigue characteristics: length 50 mm obtained by injection molding,
A rod-shaped test piece with a width of 5 mm and a thickness of 4 mm is 2 kg in an atmosphere at 30 ° C.
Servo pulser made by Shimadzu Corporation under load and 4Hz
Repeated bending fatigue test was performed by EHF-FD, and the number of times until breakage was measured. ○ those that did not break after 25,000 times, △ those that failed between 15,000 times and less than 25,000 times. What was broken after less than 0.5 million times was indicated by x.

Rigidity: The flexural modulus was measured according to ASTM D-790, 20000 kgf / cm ^{2 to} 27000 kgf / cm
The ones with ² are marked with O, and the others are marked with X.

Flowability: Flow length was measured by Archimedes type spiral flow (thickness 3 mm) at injection pressure 800 kgf / cm ² , and 20 cm or more was ◯, 15 cm or more and less than 20 cm was Δ, 1
Less than 5 cm is indicated by x. Mold release resistance: A mold gage having a length of 50 mm, a width of 5 mm and a thickness of 4 mm was attached to a projecting plate of a test piece, a strain gauge was attached to the mold, and the mold release resistance was measured.

[0031]

Examples 1 to 6 and Comparative Examples 1 to 7 The components shown in Table 1 were mixed in the amounts shown in the table, and the cylinder temperature was 270 ° C. using a vent type extruder having a diameter of 30 mm [VSK-30 manufactured by Nakatani Co., Ltd.].
Pelletized. After drying the pellets at 120 ° C. for 5 hours, an injection molding machine [J-120 manufactured by Japan Steel Works, Ltd.] was used.
SA] cylinder temperature 270 ℃, mold temperature 70 ℃
A test piece was prepared in Table 1 and the evaluation results are shown in Table 1.

The symbols showing the components shown in Table 1 are as follows. PC: Polycarbonate resin PC-1: Bisphenol A type polycarbonate resin [L-1225 manufactured by Teijin Chemicals Ltd., viscosity average molecular weight 2250]
0] PC-2: Bisphenol A type polycarbonate resin [L-1250 manufactured by Teijin Chemicals Ltd., viscosity average molecular weight 2500]
0] PC-3: Bisphenol A type polycarbonate, viscosity average molecular weight 15000 PET: Polyethylene terephthalate resin PET-1: Poly 1 ethylene terephthalate resin [TR-8580 manufactured by Teijin Ltd., intrinsic viscosity 0.8] PET-2: Polyethylene Terephthalate resin [Teijin Co., Ltd.
TR-4550 BHK, intrinsic viscosity 0.71] PET-3: polyethylene terephthalate resin, intrinsic viscosity 1.2 DP: diphosphite compound represented by the following formula

[0033]

[Chemical 8]

ES: ethylene glycol ester of montanic acid

[0035]

[Table 1]

[0036]

INDUSTRIAL APPLICABILITY The resin composition for toothbrush of the present invention can be applied to any molding method such as injection molding, can be applied to a toothbrush having a narrow neck portion, and has excellent designability, fatigue characteristics and moldability. Therefore, the molding cycle can be shortened.

Claims (1)

[Claims] 1. (A) The viscosity average molecular weight is 20,000 to 30.
100 parts by weight of a resin composition consisting of 50 to 90% by weight of an aromatic polycarbonate resin of 000 and (B) 50 to 10% by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 0.6 to 1.0, and (C) 0.001 to 1 part by weight of the diphosphite compound represented by the formula [1] and (D) an aliphatic saturated monovalent carboxylic acid having 12 to 30 carbon atoms and 3 carbon atoms
Ester with 0 or less aliphatic saturated alcohol 0.00
Elasticity of 1 to 2 parts by weight is 20000 to 27
A resin composition for a handle of a toothbrush of 000 kgf / cm ² . [Chemical 1] [Here, R ₁ and R ₂ are a hydrogen atom, an alkyl group, an arylalkyl group, an aryl group, an alkylaryl group, 2-
(4-oxyphenyl) propyl-substituted aryl group or cycloalkyl group, and R ₁ and R ₂ may be the same or different. ]