JPH0323598B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cleaning composition, and more particularly to a composition for cleaning a contaminated molding machine when changing the color of a colored thermoplastic resin or when changing the resin. Generally, when processing thermoplastic resin in a single color for a long time, cleaning the molding machine when changing to another color or resin is not a big problem. However, in many molding processes, a single mold or die is used to obtain molded products of several different colors, or the color, resin, etc. is changed each time the mold or die is replaced, so cleaning the molding machine is necessary. becomes a big problem. Molding machines are usually cleaned by pulling out the screw and scraping off the resin that has adhered to it, or by flushing out natural resin, but today, molding cycles are faster and molds can be replaced more quickly. As a result, from the perspective of molding efficiency, the time required to clean the molding machine when changing colors or resins has become relatively important.
At the same time, even if resins and the like used during cleaning can be reused, their value is considerably low, and some are treated as waste, resulting in considerable cleaning costs. In order to solve these problems, a method of cleaning using a cleaning agent mainly composed of a hard resin such as acrylic resin or a braided flat copper wire is known. However, with the above-mentioned acrylic resin-based cleaning agent, the temperature of the molding machine must be raised considerably during cleaning, and the die must be removed during cleaning. There are problems in that the copper wires become mixed in and deteriorate the appearance and physical properties.On the other hand, when using braided flat copper wires, it is expensive and difficult to handle when reusing, and it is difficult to apply. There was a problem in that the number of molding machines was limited and the die had to be removed during cleaning. The inventors of the present invention have completed the present invention as a result of intensive studies to solve the above-mentioned problems. That is, the present invention uses 1 to 15 parts by weight of a nonionic surfactant whose decomposition initiation temperature is 200°C or higher, 5 to 30 parts by weight of a metal soap, 20 to 70 parts by weight of an inorganic filler, and 20 to 70 parts by weight of an olefinic resin. A molding machine cleaning composition comprising: Surprisingly, the cleaning composition of the present invention has extremely weak adhesion to screws, cylinders, dies, etc. when used.
The screw can be easily pulled out of the cylinder to replace the screw after use, and even if the composition remains inside the die, it can be easily removed. In the present invention, nonionic surfactants with a decomposition onset temperature of 200°C or higher include polyoxyethylene alkyl ethers such as holoxyethylene stearyl ether, polyoxyethylene phenyl ethers such as polyoxyethylene nonyl phenyl ether, sorbitan fatty acid esters, etc. Sorbitan monostearate, polyoxyethylene sorbitan fatty acid ester such as polyoxyethylene sorbitan monolaurate, glycene fatty acid ester such as stearic acid monoglyceride, polyoxyethylene fatty acid ester such as polyethylene glycol monolaurate, polyoxyethylene polyoxypropylene block polymer, etc. I can give it to you. If the decomposition start temperature of the nonionic surfactant is lower than 200°C, thermal decomposition will occur during cleaning, causing gas generation and a decrease in cleaning power, which is undesirable. The content of nonionic surfactant in the entire composition is 1
~15% by weight, preferably 5 to 10% by weight; if the content is less than 1% by weight, the action as a cleaning composition will be significantly inferior, and if it exceeds 15% by weight, it will cause slippage when passed through a molding machine. The cleaning time may become longer, or in extreme cases, the molding machine may stop discharging. Note that two or more types of the above-mentioned nonionic surfactants may be used in combination. In the present invention, metal soap refers to linear aliphatic monocarboxylic acids having 12 to 18 carbon atoms, such as calcium, zinc, magnesium, barium, aluminum, etc., such as lauric acid, palmitic acid, stearic acid, oleic acid, and ricinoleic acid. metal salts. The content of metal soap in the whole composition is 5 to 30% by weight, preferably 10 to 20% by weight, and the content is 5 to 30% by weight, preferably 10 to 20% by weight.
If the amount is less than % by weight, the cleaning properties will be poor, and the peelability from the screws and cylinders will be poor, and one of the features of the present invention, which is easy replacement of the screws, will not be achieved. Also, if metal soap is used in excess of 30% by weight of the total composition, the lubricity effect will be too strong, causing it to slip between the soap and the resin being cleaned, resulting in no cleaning effect, or the soap not being discharged from the molding machine. Sometimes. In the present invention, inorganic fillers are those commonly used as fillers for plastics, such as calcium carbonate, calcium sulfate, calcium sulfite, magnesium carbonate, calcium silicate, aluminum hydroxide, barium sulfate, talc, clay, alumina, silica, and mica. , glass powder, glass bulbs, glass fibers, glass flakes, etc. The content of mineral fillers in the total composition is 20-70% by weight, preferably 40-60% by weight. Inorganic fillers have the function of removing dirt and resin by mechanical force, so if the content is less than 20% by weight, it will not be able to fully demonstrate its effect, and if it is used in excess of 70% by weight, it will become a detergent. This is undesirable because the flow becomes poor and an undesirable result is that an unnecessarily high load is placed on the molding machine. In the present invention, olefin resin refers to a polymer obtained from olefin monomers such as polyethylene, polypropylene, polybutene, ethylene-α olefin, ethylene-propylene copolymer, or olefin and vinyl acetate, fumaric acid, maleic acid, etc. Acrylic acid, methacrylic acid,
Methyl acrylate, methyl methacrylate,
It is a copolymer with a copolymerizable monomer component other than olefin, such as ethyl acrylate, and the olefin component is 50% by weight or more. Note that two or more of these olefin resins may be used in combination. The content of olefin resin in the whole composition is 20~
70% by weight, preferably 30 to 50% by weight; if the content is less than 20% by weight, the fluidity of the cleaning agent will deteriorate, and if it is used in excess of 70% by weight, the proportion of other ingredients will decrease. Since it is relatively small, the cleaning effect is poor. The molding resins used in the cleaning composition of the present invention are general thermoplastic resins, such as olefin resins such as polyethylene and polypropylene, styrene resins such as polystyrene and ABS, polyvinyl chloride, polyacetal, polyamide, and polyester resins. Examples include methyl methacrylate, polyethylene terephthalate, and polycarbonate. A further feature of the composition of the present invention is that by adjusting the balance of each component, a composition that can be washed at a wide range of temperatures from 150°C to 300°C can be obtained. The advantage is that you can set the temperature of the molding machine and clean it as is. Further, the cleaning composition of the present invention can have more effective cleaning power by changing the fluidity or by combining several types of cleaning agents depending on the fluidity characteristics of the resin to be cleaned. The cleaning composition of the present invention exhibits particularly remarkable effects as a cleaning agent for thermoplastic resin molding machines. Although the detailed reasons have not yet been fully elucidated, 4
It is thought that each component works together as follows. First, the olefin resin effectively retains the nonionic surfactant as a base for other components, thereby making it difficult for phenomena such as slip to occur. In addition, it is effective as a substrate because it can be used in a wide temperature range. It is thought that the inorganic filler has the effect of peeling off the resin that is washed by mechanical force, and also reduces the stickiness of the cleaning agent itself, making it difficult for the cleaning agent to adhere to the molding machine. In addition to acting as a lubricant to prevent peeled and contaminated resin from re-adhering, metal soap also uniformly disperses the large amount of inorganic filler contained in it, preventing the filler from getting sufficiently wet by the resin. It has the effect of preventing clogging of an extruder equipped with a wire mesh by flowing through the cylinder while remaining solidified. In particular, its action as a lubricant makes it easier to disassemble the molding machine and replace screws, etc., thereby reducing the time and labor burden. The use of a nonionic surfactant is a feature of the present invention, and since this surfactant is generally a liquid at room temperature or a solid with a low melting point, it is used at temperatures below the melting temperature of resins and metal soaps. In other words, it is effective in dispersing and removing pigments adhering to the hopper side of the molding machine, etc., and has good penetration into the resin, so it can penetrate into contaminated resin adhering to cylinders, screws, etc. This is thought to make it easier to see through and peel off. Molding machines and processing machines to which the cleaning composition of the present invention is applied include extrusion molding machines such as injection molding, extrusion molding, inflation molding, stretched filament molding, and blow molding, or kneading machines such as kneaders and Banbury mixers. etc. can be given. The cleaning composition of the present invention can be obtained by mechanical mixing using, for example, a Henschel mixer, a drum blender, a ribbon blender, etc. In some cases, a kneader or a Banbury mixer may be used to prevent scattering or to facilitate handling. The pellets may be formed into irregularly shaped pellets or cylindrical pellets using a kneading machine such as an extrusion molding machine. The cleaning composition of the present invention may further contain other additives. For example, depending on the resin, resins such as polystyrene or polymethyl methacrylate may be added to improve compatibility with contaminated resins, or plasticizers such as DOP or DOA may be added to effectively disperse surfactants. Agents etc. can be added. Examples will be explained below. For example, Chubu, %
represents the respective weight parts and weight %. Comparative Examples 1 to 3 and Examples 1 and 2 In Table 1, the cleaning compositions indicate the compositions used for cleaning. They were mixed and used. The contaminated resin was prepared by adding 0.5 parts of phthalocyanine blue (Toyo Ink Mfg. Co., Ltd., trade name: Lionol Blue NCBS) and 0.5 parts of zinc stearate to 100 parts of the resin, and uniformly mixing the mixture with a Henschel mixer. The resin after cleaning is the resin used for molding after passing through the cleaning composition.

[Table] The test was conducted by passing 500g of contaminated resin through a 3-ounce injection molding machine heated to 22°C, then adding 400g of the cleaning composition.
Washed through. After that, the specified resin is applied to a thickness of 2.
A rectangular plate of mm size was molded and the degree of remaining dirt was evaluated. Comparative Example 1, Comparative Example 2, and Example 1 are cleaning agents used when replacing a molding machine contaminated with blue-colored high-density polyethylene B (Mitsui Petrochemical Industries, Ltd., trade name Hi-Zex 2100J) with the same high-density polyethylene B. This is a comparison of effects. When cleaning with high-density polyethylene A in Comparative Example 1, the stains did not come off, and the blue color did not disappear even after 20 shots were molded. The composition of Comparative Example 2 had poor fluidity and could not be washed. The composition of Example 1 was 300
After passing about g, it becomes almost white and after passing 400g,
When molded by changing to high density polyethylene B 3
Up to the shot, a slightly bluish plate mixed with detergent was obtained, but thereafter a translucent milky white plate was obtained. Comparative Example 3 and Example 2 compare the effectiveness of cleaning agents when a molding machine contaminated with blue-colored polypropylene (trade name: Chitsuso Polypro K1016, manufactured by Chitsuso Corporation) is replaced with the same polypropylene. In Comparative Example 3, it took three times as long as usual to pass 400g of detergent through. When the resin was changed to polypropylene and molded, it took 15 shots for the blue tint to almost disappear. The composition of Example 2 is 400
When the plate was molded using polypropylene, a slightly bluish plate mixed with detergent was obtained up to the third shot, but after that, a translucent plate was obtained. Comparative Example 4, Comparative Example 5, and Examples 3 to 6.

[Table] In Table 2, the cleaning composition was homogenized using a Henschel mixer in the same manner as in Table 1. The composition of Example 6 was the same as that of Example 5, and was used in the form of cylindrical pellets through an extruder. As the contaminated resin, carbon black (manufactured by Mitsubishi Chemical Industries, Ltd., trade name: Mitsubishi Carbon #44) was used in place of the phthalocyanine blue shown in Table 1. The test was conducted using a screw diameter of 30mmφ heated to 220℃.
After passing 800 g of contaminated resin through an extrusion molding machine with a round die equipped with a wire mesh of 80 mesh at L/D: 20,
The cleaning composition was washed with 500 g of the cleaning composition, and then 300 g of a predetermined resin was applied, and the degree of stain remaining was evaluated. Comparative Example 4, Comparative Example 5, Example 3 Black colored polystyrene (Asahi Dow Co., Ltd., trade name Styron 666)
This figure compares the effectiveness of cleaning agents when replacing an extrusion molding machine contaminated with polyethylene with high-density polyethylene. In Comparative Example 4, polystyrene (Styron)
666), the black color did not disappear even after passing 300 g of high-density polyethylene B through 400 g of cleaning, and polystyrene remained, making the molding resin cloudy. When cleaning with polymethyl methacrylate in Comparative Example 5, the temperature of the molding machine was raised by 20°C.
The temperature had to be 240℃. In the case of commercially available acrylic resin cleaning agents, the temperature must be raised to 240°C or higher and the die must be removed, but the polymethyl methacrylate used this time was for molding purposes and could be passed through with the die attached. After heating, the black color disappeared through polymethyl methacrylate, but I replaced it with resin and high-density polyethylene and 300g
At the time of passing, a slight amount of polymethyl methacrylate remained and it was cloudy. In Example 3, the black color almost disappeared when 400g of the cleaning composition was passed through.
When I changed to high-density polyethylene B, it turned slightly black, but after passing 300g through it, it became translucent. Examples 4, 5, and 6 were also passed through an extruder at 220°C, and the evaluations shown in Table 2 were obtained. In Example 6, the cleaning composition was used in the form of cylindrical pellets, but the cleaning performance, which was somewhat insufficient in Example 5, could be improved by forming it into pellets.

Claims (1)

[Claims] 1 Molding consisting of 1 to 15 parts by weight of a nonionic surfactant whose decomposition onset temperature is 200°C or higher, 5 to 30 parts by weight of metal soap, 20 to 70 parts by weight of an inorganic filler, and 20 to 70 parts by weight of an olefin resin. Composition for machine cleaning.