JP7315179B2 - Cleaning agents for molding machines - Google Patents

Description

The present invention relates to a cleaning agent for molding machines.

Injection molding machines and extrusion molding machines are mainly used for molding thermoplastic resins. After use of these molding machines, the resin, additives such as pigments added to the resin, and degraded resin generated during molding remain in the molding machine. If the next resin molding process is performed while these residues are present, the residues will be mixed in the molded product, and the appearance of the molded product will be deteriorated, and the expected physical properties of the resin will be deteriorated.

In order to reduce the influence of such preceding resin, the inside of the molding machine may be washed with the resin to be used in the next molding process. However, this method requires a large amount of resin to wash the molding machine, which is costly, and has the problem that dirt in the molding machine cannot be completely removed.

Therefore, various cleaning agents for cleaning molding machines have been investigated. For example, Patent Document 1 proposes a detergent for molding machines having a melt mass flow rate of 10 to 35 g/10 minutes.

JP 2018-069473 A

However, a large amount of cleaning agents such as those described above are sometimes required to clean the interior of the molding machine. If the amount of resin (cleaning agent) required for cleaning increases, a large amount of waste will be discharged, which is not preferable from the viewpoint of realizing carbon neutrality, which has been attracting attention in recent years.

In view of the above, an object of the present invention is to provide a cleaning agent for a molding machine that exhibits a good cleaning effect on residual resin materials such as resins or resin compositions that remain in the molding machine after molding processing, and that can be removed in a small amount.

As a result of intensive studies to solve the above problems, the present inventors found that the problems can be solved by the present invention described below. That is, the present invention is as follows.

[1] A cleaning agent for a molding machine comprising a thermoplastic resin component, a surfactant, and an inorganic filler of 75 parts by mass or less per 100 parts by mass of the thermoplastic resin component, wherein the melt mass flow rate (190°C, load 2.16 kg) of the thermoplastic resin component is 0.05 to 15 g/10 minutes, and the surfactant is a nonionic surfactant having a thermal decomposition temperature of 240°C or higher.
[2] The cleaning agent for a molding machine according to [1], which contains 0.5 to 15 parts by mass of the surfactant with respect to 100 parts by mass of the thermoplastic resin component.
[3] The cleaning agent for molding machines according to [1] or [2], which is for injection molding machines.

According to the present invention, it is possible to provide a cleaning agent for a molding machine that exhibits a good cleaning effect on residual resin materials such as resins or resin compositions remaining in a molding machine after molding processing, and that can be removed in a small amount. As a result, it is possible to reduce the amount of resin that is discarded, and it is possible to contribute to the realization of carbon neutrality, which has been attracting attention in recent years.

A molding machine cleaning agent according to one embodiment (this embodiment) of the present invention contains a thermoplastic resin component, a surfactant, and an inorganic filler of 75 parts by mass or less per 100 parts by mass of the thermoplastic resin component. Various components including each component will be described below.

(Thermoplastic resin component)
The thermoplastic resin component according to the present embodiment has a melt mass flow rate (190° C., load 2.16 kg) of 0.05 to 15 g/10 minutes, preferably 0.05 to 10 g/10 minutes, more preferably 0.05 to 8 g/10 minutes, and even more preferably 0.05 to 7 g/10 minutes.

If the melt mass flow rate (MFR) is less than 0.05 g/10 minutes, the replacement property (dischargeability of the cleaning agent) will deteriorate, and if it exceeds 15 g/10 minutes, the detergency will deteriorate.

Here, the MFR of the thermoplastic resin component according to the present embodiment shall be measured under conditions of 190° C. and a load of 2.16 kg in accordance with ISO1133.
Specifically, a dried thermoplastic resin component is put into a cylinder (with an inner diameter of 9.5 mmφ) preheated to the measurement temperature (190°C). After the thermoplastic resin component reaches the measurement temperature (190 ° C.), a predetermined load (2.16 kg) is applied to the piston inserted into the cylinder to push out the thermoplastic resin component from the orifice (inner diameter 2.095 mmφ) attached to the bottom of the cylinder. Then, the mass of the thermoplastic resin component extruded in 10 minutes is determined as MFR.

The "thermoplastic resin component" of the present embodiment is a thermoplastic resin (all of them if there are multiple types), or a mixture of thermoplastic resins (all of them if there are multiple types) and paraffin, and has an MFR of 0.05 to 15 g/10 minutes.

The thermoplastic resin includes polyethylene, polypropylene, polystyrene, AS resin, ABS resin, polybutene resin, polymethyl methacrylate resin and the like, and polyethylene is preferred.

Examples of polyethylene include modified polyethylene resins such as high-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polyethylene obtained using a metallocene compound as a polymerization catalyst, cyclic polyethylene, maleic anhydride-modified polyethylene, glycidyl (meth) acrylate-modified polyethylene, and 2-hydroxyethyl (meth) acrylate-modified polyethylene.

Among them, from the viewpoint of ease of adjustment of MFR and effective cleaning of dirt on screws and cylinders, thermoplastic resins containing ultra high molecular weight polyethylene as a main component (preferably 50% by mass or more, more 80% by mass or more) are preferable.
ここでいう超高分子量ポリエチレンとは、重量平均分子量は１００万以上（好ましくは２００万～１２００万、より好ましくは４００万～１０００万）のポリエチレンをいい、エチレン単独重合体のみならず、エチレンと、炭素数３～２０のα－オレフィン、炭素数３～２０の環状オレフィン、式ＣＨ _２ ＝ＣＨＲ ^１ （Ｒ ^１は炭素数６～２０のアリール基である）で表される化合物、及び炭素数４～２０の直鎖状、分岐状または環状のジエンより成る群から選ばれる少なくとも１種のオレフィンとを共重合させたものも含まれる。

Moreover, from the viewpoint of plasticization and peelability, a mixture (combination) of a thermoplastic resin and paraffin may be used. Liquid paraffin is preferred as the paraffin. Liquid paraffin preferably has a kinematic viscosity at 40° C. of 1 to 200 mm ² /s, more preferably 5 to 100 mm ² /s, as measured by the method specified in JIS K2283. When the 40° C. kinematic viscosity is within the above range, the handling becomes easy and the dispersibility of liquid paraffin in the resin becomes good.

The mass ratio [paraffin/thermoplastic resin] of paraffin and thermoplastic resin (total thereof if there are multiple types) is preferably 0.4 or less, more preferably 0.3 or less. By being 0.4 or less, it is possible to maintain viscosity and effect effective in detergency.
When paraffin is contained, the lower limit of [paraffin/thermoplastic resin] is preferably about 0.01.

In order to set the MFR of the thermoplastic resin component to 0.05 to 15 g / 10 minutes, the thermoplastic resin within the range may be used, or a plurality of types of thermoplastic resins may be mixed to adjust the blending so as to fall within the range.
preferable.

(Surfactant)
The cleaning agent for a molding machine according to the present embodiment further contains a surfactant from the viewpoint of penetrating resin material residue and improving cleaning performance, and the surfactant used is a nonionic surfactant having a thermal decomposition temperature of 240° C. or higher. Nonionic surfactants are preferred from the viewpoint of feeding properties (sliding properties) of the thermoplastic resin component inside the molding machine and versatility.

In addition, the above-mentioned "thermal decomposition temperature of 240 ° C. or higher" means that the thermal decomposition temperature is higher than the molding temperature assumed at the time of molding such as injection molding, and when washing at the same temperature as injection molding, thermal decomposition is suppressed near that temperature. As a result, the penetration and cleaning effect of the surfactant on the residual resin material can be sufficiently exhibited. Therefore, if the thermal decomposition temperature is less than 240° C., the surfactant is likely to thermally decompose, and its function cannot be fully exhibited. The thermal decomposition temperature is preferably 250°C to 280°C, more preferably 280°C to 300°C.

Here, the thermal decomposition temperature of the surfactant is measured by thermogravimetric analysis (TGA), where 10 mg of a sample is heated at a constant heating rate (10 ° C./min) in an air atmosphere, and the temperature is obtained from the position of the intersection of the tangent line before the initial reduction and the tangent line after the reduction.

The above nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene phenyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyglycerin fatty acid esters, polyoxyethylene fatty acid esters, etc., and those having a thermal decomposition temperature of 240° C. or higher can be mentioned, but polyglycerin fatty acid esters are preferred from the viewpoint of maintaining performance due to the high thermal decomposition temperature in an air atmosphere.

The polyglycerin fatty acid ester is preferably represented by the following formula.

In the above formula (1), n is a number of 2 to 10, and R ¹ , R ³ and multiple R ² are each independently hydrogen or a fatty acid residue having 8 to 20 carbon atoms.
n is preferably a number of 2 to 8, and more preferably a number of 3 to 5, from the viewpoint of heat resistance, washability and releasability. R ¹ , R ³ , and multiple R ² s are each independently preferably hydrogen or 12 to 20 carbon atoms, preferably 14 to 20 carbon atoms, from the viewpoint of heat resistance, washability, and releasability.
Fatty acids that serve as fatty acid residues include caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid. Among them, it is preferable to contain palmitic acid and/or stearic acid.

The nonionic surfactant having a thermal decomposition temperature of 240° C. or higher is preferably contained in an amount of 0.5 to 15 parts by mass, more preferably 0.5 to 13 parts by mass, based on 100 parts by mass of the thermoplastic resin component. When the content is 0.5 to 15, the viscosity effective for detergency and the detergency of the present invention can be maintained satisfactorily.

(Inorganic filler)
The cleaning agent according to the present embodiment further contains an inorganic filler from the viewpoint of improving the cleaning property by the polishing effect and adjusting the viscosity. Examples of inorganic fillers include calcium carbonate, calcium sulfate, calcium sulfite, magnesium carbonate, calcium silicate, barium sulfate, talc, mica, clay, montmontlilonite, smectite, kaolin, glass fiber, glass milled fiber, glass flakes, carbon fiber, carbon flakes, carbon beads, carbon milled fiber, silica, ceramic particles, ceramic fibers, and ceramic balloons. Among them, kaolin, calcium carbonate and talc are preferred, and talc is more preferred.

The volume-average particle size of the inorganic filler is not particularly limited, and is preferably 0.1 to 50 μm, more preferably 1 to 30 μm, from the viewpoints of the cleaning effect of residual resin materials, ease of blending into thermoplastics, and the like. The volume average particle diameter can be measured by a laser diffraction scattering method.

In the present embodiment, the inorganic filler contains 75 parts by mass or less, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and 40 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin component. If it exceeds 75 parts by mass, it becomes difficult to maintain effective viscosity and cleaning effect.
The inorganic filler is preferably contained in an amount of 2 parts by mass or more, more preferably 5 parts by mass or more, with respect to 100 parts by mass of the thermoplastic resin component. When the content is 2 parts by mass or more, it becomes easy to obtain detergency based on the inorganic filler.

Here, from the viewpoint of exhibiting the respective effects of the inorganic filler and the nonionic surfactant according to the present embodiment in a well-balanced manner, the mass ratio of these (inorganic filler/nonionic surfactant) is preferably 0.2 to 100, more preferably 0.2 to 60, even more preferably 1.5 to 10, among them, preferably 1.5 to 5, more preferably 1.5 to 4, and even more preferably 1.5 to 3.8. .

(metallic soap)
The cleaning agent for molding machines of the present embodiment preferably further contains a metal soap.
Examples of metal soaps include metal salts of linear aliphatic monocarboxylic acids having 12 to 18 carbon atoms, and examples of linear aliphatic monocarboxylic acids having 12 to 18 carbon atoms include lauric acid, palmitic acid, stearic acid, oleic acid, and ricinoleic acid. Metal salts include calcium salts, zinc salts, magnesium salts, barium salts, aluminum salts and the like.

(Optional component)
The resin composition of the present invention may optionally contain optional components. Examples thereof include heat stabilizers, metallic soaps, antifoaming agents, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, lubricants, release agents, antistatic agents, and flame retardants.

Examples of heat stabilizers added to improve heat stability during production include phosphorus antioxidants, hindered phenol antioxidants, phosphite antioxidants, lactone antioxidants, and the like. From the viewpoint of effectively obtaining the effect of improving thermal stability, the thermal stabilizer is preferably contained in an amount of 0.1 to 4.0 parts by mass, more preferably 0.5 to 3.0 parts by mass, based on 100 parts by mass of the thermoplastic resin component.

The cleaning agent according to the present embodiment is obtained by mixing each material with, for example, a tumbler mixer or a high-speed mixer and kneading (melting and kneading) with an extruder. The shape thereof may be powder, granule, pellet, flake, or a mixture thereof.

Here, melt-kneading can be performed using, for example, a Banbury mixer, two-roll, three-roll, single-screw kneading extruder, and twin-screw kneading extruder. Melt-kneading may be performed in one step or in multiple steps. The melt-kneading temperature is not particularly limited as long as the thermoplastic resin is sufficiently melted and heat deterioration of the thermoplastic resin is not a problem. For example, the melt-kneading temperature is preferably about 150 to 250°C.

The melt-kneaded product can be formed into powder, granules, pellets, and flakes by a known method, as required.

(Washing method)
The cleaning method of a molding machine using the cleaning agent for molding machines according to the present embodiment is a method of charging the cleaning agent into the cylinder of the resin molding machine, heating the cleaning agent to plasticize (melt) and hold the cleaning agent, and then discharging the plasticized cleaning agent from the cylinder of the resin molding machine.

Applicable resin molding machines include, for example, injection molding machines and extrusion molding machines, but are not particularly limited to these as long as they have a cylinder for heat-melting and kneading (mixing) the resin. That is, the cleaning agent of the present invention can be widely applied to known resin molding machines.
The cylinder temperature of the resin molding machine when heating the detergent is preferably 180° C. or higher, more preferably 200° C. or higher, and even more preferably 240° C. or higher, although it depends on the temperature at which the preceding resin was treated. Although the upper limit of the heating temperature is not particularly limited, it is usually about 400°C.

The cleaning agent for a molding machine of the present invention can efficiently clean and discharge a small amount of residual resin material contained in molding materials such as the resin itself and dyes and pigments and remaining in the molding machine at the end of predetermined operations in the extrusion molding machine and the injection molding machine. Therefore, it can be suitably used as a cleaning agent for cleaning the inside of a thermoplastic resin molding machine, and the molding machine is preferably an extrusion molding machine or an injection molding machine, and more preferably an injection molding machine. That is, the cleaning agent for molding machines of the present invention is preferably a cleaning agent for extruders or injection molding machines, and more preferably a cleaning agent for injection molding machines.

Preceding resins include PA (polyamide), PMMA (polymethyl methacrylate (acrylic)), PLA (polylactic acid), ABS (acrylonitrile-butadiene-styrene copolymer), AS (acrylonitrile-styrene copolymer), PVC (polyvinyl chloride), PVDF (polyvinylidene fluoride), TPU (polyurethane), PC (polycarbonate), PET (polyethylene terephthalate), PB. It can be favorably applied to highly polar resins such as T (polybutylene terephthalate) and POM (polyacetal), and resin compositions containing these resins as main components (50% by mass or more, preferably 70% by mass or more). Moreover, it can be applied favorably to general-purpose resins.
A highly polar resin is a resin having a polar group such as a carboxyl group, an amino group, an ester group, a sulfone group, a cyano group, a thiol group, a hydroxyl group, and an amide group.

EXAMPLES Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these.

<Preparation of detergent for molding machine>
Thermoplastic resins A to F, nonionic surfactants A and B, inorganic filler, and metal soap were mixed in a tumbler according to the formulations shown in Tables 1 and 2 below (unit: parts by mass), and then melt-kneaded at 200° C. using a twin-screw kneading extruder (JSW TEX30α, manufactured by The Japan Steel Works, Ltd.) to form pellets (diameter: 3 mm, height: 3 mm) to prepare cleaning agents for molding machines.

The thermoplastic resins A to F, nonionic surfactants A and B, inorganic fillers, and metal soaps used are as follows.
・Thermoplastic resin A
Pellets/thermoplastic resin B of ultra-high molecular weight polyethylene (weight average molecular weight of 1 million or more) with MFR of 0.1 g/10 min
Pellets/thermoplastic resin C of ultra high molecular weight polyethylene having MFR of 1.5 g/10 min, consisting of ultra high molecular weight polyethylene (weight average molecular weight of 1,000,000 or more) having MFR of 0.1 g/10 min and high density polyethylene (MFR of 13 g/10 min)
Pellets/thermoplastic resin D of ultra-high molecular weight polyethylene having MFR of 5.0 g/10 min, consisting of ultra-high molecular weight polyethylene (weight average molecular weight of 1,000,000 or more) having MFR of 0.1 g/10 min and high-density polyethylene (MFR of 13 g/10 min)
Pellets/thermoplastic resin E of ultra-high molecular weight polyethylene having MFR of 12.0 g/10 min, consisting of ultra-high molecular weight polyethylene having MFR of 0.1 g/10 min (weight average molecular weight of 1,000,000 or more), high-density polyethylene (MFR of 13 g/10 min), and liquid paraffin
Pellets/thermoplastic resin F of ultra-high molecular weight polyethylene having MFR of 0.03 g/10 min, consisting of ultra-high molecular weight polyethylene (weight average molecular weight of 1,000,000 or more) having MFR of 0.1 g/10 min and high-density polyethylene (MFR of 0.02 g/10 min)
Ultra high molecular weight polyethylene pellets and nonionic surfactant A having an MFR of 18.0 g/10 min, consisting of an ultra high molecular weight polyethylene (weight average molecular weight of 1 million or more) having an MFR of 0.1 g/10 min, a high density polyethylene (MFR of 13 g/10 min), and liquid paraffin.
Polyglycerin fatty acid ester (SY Glister TS-3S, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., thermal decomposition temperature 290 ° C., polyglycerin polymerization degree (n in formula (1)): 4 (tetraglycerin))
・ Nonionic surfactant B
Polyethylene glycol monostearate (polyoxyethylene monostearate) ethylene oxide polymerization degree 10, fatty acid carbon number 16-18, thermal decomposition temperature 230°C)
・ Inorganic filler talc powder (manufactured by Hayashi Kasei Co., Ltd., volume average particle size 25 μm)

Thermoplastic resins A to F (thermoplastic resin components) were measured for MFR (190° C., load 2.16 kg) by MELT FLOW INDEX TESTER (model SAS2000) manufactured by Yasuda Seiki Seisakusho.

<Evaluation method>
(1) Resin molding A mixture obtained by adding 2.5 parts by mass of ROYAL BLACK 9031P (manufactured by Koshigaya Kasei Co., Ltd.), which is a black pigment-containing masterbatch, to 100 parts by weight of homopolypropylene Mitsui Polypro J105W (manufactured by Mitsui Polypro Co., Ltd.), 500 g of a mixture was added to an injection molding machine (manufactured by Japan Steel Works, Ltd.) heated to 240 ° C. and having a clamping pressure of 55 tons, and a nozzle was inserted into the mold. I discharged everything from the cylinder without touching it.

(2) Cleaning evaluation After the above molding, the temperature of the injection molding machine was kept at 240°C, and after the molding resin remaining from the injection molding machine was discharged by rotating the screw, a predetermined amount of cleaning agent for the molding machine was added from the hopper, and the cleaning treatment was performed by rotating the screw to discharge the cleaning agent. The above cleaning treatment was performed until the color of the discharged resin disappeared and the color of the cleaning agent for the molding machine became the color of the cleaning agent alone, and the amount of cleaning agent required for cleaning was obtained from the amount of cleaning agent used until the cleaning was completed. Cleaning was evaluated according to the following criteria. Tables 1 and 2 show the results.

-criterion-
A: The amount of detergent is less than 300 g B: The amount of detergent is more than 300 g and less than or equal to 400 g C: The amount of detergent is more than 400 g and less than or equal to 500 g D: The amount of detergent is more than 500 g and less than or equal to 550 g

Claims (3)

Containing a thermoplastic resin component, a surfactant, and an inorganic filler of 75 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin component,
The thermoplastic resin component has a melt mass flow rate (190° C., load 2.16 kg) of 0.05 to 15 g/10 minutes,
A cleaning agent for a molding machine, wherein the surfactant is a nonionic surfactant having a thermal decomposition temperature of 240° C. or higher , the nonionic surfactant is a polyglycerin fatty acid ester , and the mass ratio of the inorganic filler and the nonionic surfactant (inorganic filler/nonionic surfactant) is 0.2 to 60. The cleaning agent for a molding machine according to claim 1, which contains 0.5 to 15 parts by mass of said surfactant with respect to 100 parts by mass of said thermoplastic resin component. The cleaning agent for molding machines according to claim 1 or 2, which is for injection molding machines.