JPH0321653A - Resin composition for washing - Google Patents

Abstract

PURPOSE:To obtain the subject resin composition for washing capable of readily washing various molding machines using only a small amount thereof by blending a specified high-density polyethylene with polyethylene wax, a neutral salt of an alkylbenzenesulfonic acid and an inorganic filler. CONSTITUTION:With (A) a high-density polyethylene having <=1 melt index and <=10, preferably <=8 molecular weight distribution Q (Mw/Mw), (B) 1-10wt.% polyethylene wax preferably having 1000-10000 molecular weight, (C) 1-20wt.%, preferably 5-15wt.% neutral salt of an alkylbenzenesulfonic acid having a 10-18C alkyl group (e.g. magnesium dodecylbenzenesulfonate), (D) 1-20wt.%, preferably 3-15wt.% inorganic filler (e.g. calcium carbide or silica) and, as necessary, a wax, an antioxidant, etc., are blended.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cleaning resin composition used for cleaning the insides of various molding machines.

More specifically, the present invention relates to a cleaning resin composition that has high viscoelasticity when melted, has a narrow molecular weight distribution, and contains low-molecular polyethylene wax, a neutral salt of alkylbenzenesulfonic acid, and an inorganic filler in a high-density polyethylene resin.

(Prior Art) In the field of plastic molding, the trend is toward high-mix, low-volume production, and with the advent of high-performance engineering plastics, the frequency of color changes or resin changes in molding machines is rapidly increasing.

Conventionally, when changing colors or resins, the method of removing contamination from the preceding resin in the molding machine was to pull out the contaminated screw of the molding machine and brush and clean the screw and the inner wall of the cylinder of the molding machine. A method has been adopted in which the inside of the molding machine is co-washed using an uncolored resin as a cleaning resin after the screw is pulled out. However, with this method of pulling out the screw and brushing it, or washing the screw and cylinder of the molding machine with cleaning resin, it takes a long time to completely clean the inside of the molding machine, resulting in a loss of time. It had the disadvantage of being large. Therefore, various cleaning agents have been developed to solve these problems.

For example, cleaning agents containing acrylic resin as a main component and compositions in which sodium alkylbenzene sulfonate, talc, zinc stearate, etc. are blended with linear low-density polyethylene have been proposed (JP-A-60-439411). ).

However, in the case of cleaning agents mainly composed of acrylic resin, since the acrylic resin has a high melt viscosity, a high load is applied to the molding machine during cleaning, and if the temperature inside the molding machine is raised to lower the melt viscosity, the melt viscosity of the acrylic resin is high. The drawback is that the acrylic resin is subject to thermal decomposition. Moreover, when using the cleaning agent, the dies, wire mesh, etc. of the ceremonial machine must be removed before use, which is complicated and time-consuming.

Further, if the cleaning agent remains in the molding machine even after cleaning is completed, the cleaning agent may be mixed into subsequent molded products, resulting in foreign matter that impairs the appearance or deteriorates physical properties.

In addition, cleaning agents using sodium alkylbenzenesulfonate, Merck, etc. for linear low-density polyethylene have low viscoelasticity when melted in the molding machine, so their ability to remove the preceding resin, that is, the cleaning ability, is low, and the inorganic filler If a large amount of cleaning agent is mixed, the cleaning agent itself tends to remain on the wall of the kaikata machine, which may cause problems such as having to use a large amount of cleaning resin to remove this residual cleaning agent. There are drawbacks.

In addition, the present inventors proposed a thermoplastic resin composite (Patent Publication No. 195045/1983), which is a thermoplastic resin mixed with a neutral salt of an alkylbenzenesulfonic acid and a water-repellent compound, but it has even better cleaning ability. something is desired.

(Problems to be Solved by the Invention) The present inventors have developed a method for late molding that can easily change the color and resin in various thermoplastic resin molding machines in a short time using a small amount and simple operation. We conducted extensive research in order to obtain a resin composition for in-machine cleaning.

As a result, it has a high viscoelasticity when melted and a narrow molecular weight distribution, and contains a high-density polyethylene resin, a low-molecular polyethylene wax, a neutral salt of an alkylbenzenesulfonic acid whose alkyl group has 10 to 18 carbon atoms, and an inorganic filler. The inventors have discovered that the resulting composite sole can be used as a cleaning resin assembly with significantly improved cleaning effects, and have completed the present invention based on this knowledge.

(Means for Solving the Problems) The present invention has the following structure.〇(1) Polyethylene wax is added to a high-density polyethylene resin having a melt index of 1.0 or less and a Q value representing molecular weight distribution of 10 or less. 1 to 10% by weight of a neutral salt of an alkylbenzenesulfonic acid whose alkyl group has 10 to 1 carbon atoms and 1 to 20% by weight of an inorganic filler. Resin composition.

(2) The above-mentioned (
The cleaning resin composition according to item 1).

The high density polyethylene resin used in the present invention has a melt index of 1.0 or less and a molecular weight distribution (Q value) of 10 or less, preferably 8 or less. Here, the Q value is determined by measuring gel vermiaction, Q = My / Mn
This is the numerical value obtained as .

When cleaning the inside of a molding machine using a cleaning resin mixture obtained when the melt index of high-density polyethylene exceeds 1, it is washed in the molding machine.

Furthermore, if a high-density polyethylene resin with a wide molecular weight distribution and a Q value exceeding 10 is used, when cleaning a molding machine using the resulting cleaning resin composition, the viscoelasticity of the molten resin will decrease and the cleaning ability will decrease. So I don't like it.

The molecular weight of the polyethylene wax used in the present invention is not particularly limited, but preferably has a molecular weight of 1000 to 10,000. In addition, the blending amount of the polyethylene wax is 1
If the amount exceeds 10% by weight, it becomes difficult to remove, and if the amount exceeds 10%, the lubricity becomes too strong and the cleaning ability decreases, which is not preferable.

The neutral salt of alkylbenzenesulfonic acid used in the present invention includes sodium salt, calcium salt, magnesium salt, potassium salt, etc. of alkylbenzenesulfonic acid having an alkyl group having 10 to 18 carbon atoms. The amount of the neutral salt of alkylbenzenesulfonic acid to be blended is 1 to 20% by weight, preferably 5 to 15% by weight. If the blending amount is less than 1%, cleaning power in the molding machine will not be achieved, and if it exceeds 20 weight φ, the neutral salt of the alkylbensene sulfonic acid will remain in the molding machine and the fluidity of the molten resin will be affected during cleaning. This is not desirable because it will worsen the situation and put a high load on the ceremonial machine.

Inorganic fillers used in the present invention include magnesium carbonate,
An inorganic filler that is usually added to polyolefin resin, such as calcium carbonate, calcium sulfate, magnesium silicate, silica, or alumina, may be used. It works by scraping off dirt and adhering resin.

The amount of the inorganic filler is 1 to 20% by weight, preferably 3% by weight.
~15 weight. If the amount is less than 1 weight, the cleaning ability will be insufficient, and if it exceeds 20 weight, the melt flowability of the cleaning resin composition will decrease, and the molding machine will be overloaded during cleaning. Otherwise, the cleaning resin composition may remain in the molding machine, making it difficult to replace it with a subsequent cleaning resin, which is undesirable. In addition, the cleaning resin composition of the present invention may optionally contain water-repellent compounds such as waxes such as volibrobylene wax and carnabar wax, silicone, wax, and metal salts of higher fatty acids (e.g., calcium stearate, magnesium stearate). Can be used.

Furthermore, phenolic antioxidants, thio-based antioxidants, phosphorus-based antioxidants, etc., which are usually blended into polyolefin resins, can be blended.

In addition, the cleaning resin composition of the present invention may optionally contain a surfactant which is a sulfonate compound such as sodium alkyl ether sulfate having an alkyl group having 6 to 20 carbon atoms and sodium α-olefin sulfonate. be able to.

The cleaning resin composition of the present invention has a melt index of 1.

A predetermined amount of high-density polyethylene with a Q value of 0 or less and a Q value of 10 or less, polyethylene wax, a neutral salt of an alkylbenzenesulfonic acid having an alkyl group of carbon alO to 1 day, and an inorganic filler are stirred and mixed using a mixing device such as a Henschel mixer ( (trade name) and stirred and mixed for 1 to 5 minutes, and the mixture is melt mixed and extruded using a single screw extruder or twin screw extruder at a melt mixing temperature of 180°C to 230°C to form pellets. You can also get it.

(Examples) Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(1) Tests of cleaning ability in Examples and Comparative Examples were conducted in the following manner.

After 15 shots of black pellets of acrylonitrile putadiene styrene resin (ABS resin) or modified polyphenylene oxide containing 1 weight or more of carbon black were injection molded using a 35-ton injection molding machine, each example and comparison were made. After injection molding using 100 grams of each of the cleaning resin composites obtained in each example, injection molding was repeated using the cleaning resin until the molded product obtained with the molding machine was no longer colored. The amount of cleaning resin required was determined, and the time until the molded article was no longer colored was measured as the cleaning time.

．． (2) GPC measurements were conducted under the following conditions.

Equipment: GP0 150c Column: Higashi-TSKGEL GMH6-HT solution
Medium: ODCB Temperature: 135°C Flow rate: 1. The Q value used as a measure of molecular weight distribution is expressed as follows.

The strands were extruded and cut with a pelletizer at a temperature of 200° C. and a die temperature of 210° C. to obtain a granular cleaning resin composition.

Using this cleaning resin composition, carbon plaque 1%
A cleaning test was conducted on an injection molding machine contaminated with ABS resin. Example 1 High-density polyethylene/(melt index JIS
K6'i'60 2 0.3O Q value 6. +7) 3.45 Ic9, magnesium dodecylbenzenesulfonate 0.75kg, calcium carbonate 0.50#, polyethylene wax (
A mixture having a number average molecular weight of 1500) 0.30 or more was placed in a Henschel mixer (trade name) having an internal volume of 207, and mixed by stirring at a rotational speed of 500 rpm for 3 minutes. The obtained mixture was supplied to the hopper of a single screw extruder having a cylinder diameter of 35 m, and the cylinder was heated. The amount of polypropylene required was 80 grams (4 shots) and the time required for washing was 9 minutes.

Example 2, high density polyethylene (melt index: 0.3O
Q value 6.7) 4.2 5 #, calcium dodecylbenzenesulfonate 0.40 kg, silica (average particle size 3.5 microns or less) 0.20 polyethylene wax (number average molecular weight 1500) same as Example 1 The mixture was mixed under certain conditions and pelletized to obtain a granular cleaning resin composition.

A cleaning test was conducted on this cleaning resin assembly/forming machine. The inside of the molding machine was replaced with a cleaning resin assembly and cleaned at a cylinder temperature of 300°C. The required amount of polyethylene terephthalate was 280 grams (14 shots), and the time required for washing was 19 minutes.

Example 3 High density polyethylene (melt index 2 0.80
Q value 9.2) 2.95 kg, sodium dodecylbenzenesulfonate 0.90~, polyethylene.

A cleaning test was conducted according to Example 1 using the obtained cleaning resin composition. The amount of polypropylene used as the cleaning resin was 140 grams (7 shots), and the time required for cleaning was 12 minutes.

Example ↓ High density polyethylene (melt index 2 0.80Q
Value 9.2) 4.0 5 #, potassium dodecylbenzenesulfonate 0.20 kg, magnesium carbonate 0.3
0kg, polyethylene wax (number average molecular weight 1150
0) 0.45 kg was mixed and pelletized under the same conditions as in Example 1; a cleaning test was conducted in accordance with Example 1 using the obtained cleaning resin composition. The amount of polypropylene used as cleaning resin is 120 grams (6 shots)
The time required for washing was 11 minutes.

Example 5 High density polyethylene (melt index ゜0.3O
Q value 6.7) 3. '/Okfl, 0.45 kg of magnesium dodecylhensensulfonate, 0.65 kg of magnesium carbonate, and 0.20 kg of polyethylene wax (number average molecular weight 1500) were mixed under the same conditions as in Example 1, and pellets were prepared. It became. A cleaning test was conducted according to Example 2 using the obtained cleaning resin composition. Polie, a cleaning resin (12 shots),
The time required for washing was 17 minutes.

Comparative Example 1 High density polyethylene (melt index = 0.70
Q value 1 3.2) 3.4 5 k9, magnesium dodecylbenzenesulfonate O. '7 5 tcy,
0.50# of calcium carbonate and 0.30# of polyethylene wax (number average molecular weight 1500) were mixed under the same conditions as in Example 1 and pelletized. A cleaning test was conducted in accordance with Example 1 using the obtained cleaning resin composition. The amount of polypropylene used as the cleaning resin was 440 grams (22 shots), and the time required for cleaning was 27 minutes.

Comparative example 2 High density polyethylene (melt index = 2.20
Q value 8.4) 3.45 kg, magnesium dodecylbenzenesulfonate 0.75 IC9, calcium carbonate 0.50 fi, and polyethylene wax (number average molecular weight 1500) 0.30 kg were mixed under the same conditions as in Example 1, Pelleted. Using the obtained cleaning resin composition, a cleaning test was conducted according to Example 1. The amount of polypropylene used for cleaning was 580 grams (2
(9 shots), and the time required for cleaning was 34 minutes.

Comparative Example 3 Linear low density polyethylene (melt index: 2.5
O Q value 1 3.0 ) 2.5 0 kg, sodium dodecylbenzenesulfonate 0.50 kg, Merck 2.30 kg, sodium stearate 0.1 kg,
Zinc stearate 0.10~ was mixed under the same conditions as in Example 1 and pelletized. A cleaning test was conducted according to Example 1 using the obtained cleaning resin composition. The amount of boribropylene used, which is a cleaning resin, is 680 grams (
34 shots), and the time required for cleaning was 39 minutes.

The results of the assembly and cleaning tests of Examples 1 to 5 and Comparative Example 1 are summarized in Table 1.

(Effects of the Invention) The cleaning resin composition of the present invention exhibits an extremely excellent cleaning effect for cleaning a molding machine when changing grades in plastic molding processing.

By using the cleaning resin composition of the present invention, the amount of subsequent cleaning resin used can be significantly reduced and the time required for cleaning can be significantly reduced compared to when using conventional cleaning resin compositions. It can be shortened to width. For example, when switching from the previous ABS resin to polypropylene, the amount of polypropylene required for subsequent cleaning can be reduced to 1/3 or less, and the cleaning time can also be shortened to 1/3 or less.

that's all

Claims (2)

[Claims] (1) High-density polyethylene with a melt index of 1 or less and a Q value representing molecular weight distribution of 10 or less, 1 to 10% by weight of polyethylene wax, and the number of carbon atoms in the alkyl group is 1
Neutral salt of alkylbenzenesulfonic acid having 0 to 18 1
A cleaning resin composition characterized in that it contains 1 to 20% by weight of an inorganic filler and 1 to 20% by weight of an inorganic filler. (2) The cleaning resin composition according to claim (1), which is formed into pellets by melt-kneading.