JP2632552B2 - Resin composition for purging plastic molding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resin composition for purging a plastic molding machine, and more particularly, to a polyolefin resin, a vinyl chloride resin, a polystyrene resin, and a peroxide-added resin in a plastic molding machine. When purging thermoplastic adhesive resins such as various copolymers, polyamides, polyesters, etc., purging can be effectively performed at resin temperatures of 250 ° C or lower as well as 250 ° C or higher. The present invention relates to a resin composition for use.

[Prior art] Conventionally, resin compositions for purging in plastic molding machines include polyethylene, inorganic fillers such as white carbon, talc and clay, sodium lauryl sulfonate, alkylamine hydrochloride, polyoxyethylene sorbitan monostearate and the like. With the addition of a surface active agent
No.-14923), comprising a crosslinked polyethylene resin having a gel fraction of 35 to 90% (JP-B No. 61-4413). In a thermoplastic resin, an inorganic filler and paraffin, wax, higher fatty acid or amide, ester thereof, Those comprising a lubricant selected from higher alcohols, polyglycols, polyglycerols, higher fatty acid metal soaps and the like (Japanese Patent Publication No. 62-54647) have been proposed.

[Problems to be Solved by the Invention] However, these resin compositions for purging are generally effective at a temperature lower than 250 ° C, but the resin temperature in the system is low as in extrusion coating, wire coating extrusion, pipe extrusion and the like. 250
When the temperature is higher than or equal to ° C., the additives in the resin composition for purging used for purging are decomposed, thereby causing smoke and foaming, and adversely affecting the working environment such as odor. When a conventional resin composition for purging is used in an extruder, a scorch is generated in a screw, an adapter or a die portion, which has a great adverse effect such as defective molding on a product to be produced next.

Therefore, when performing purge cleaning using a conventional plastic molding machine purging resin composition, the screw, adapter or die used at 250 ° C or higher is once purged at a temperature lower than 250 ° C at which the purging resin composition does not cause thermal decomposition. Purge cleaning has to be performed at a low temperature, which requires complicated means such as time loss in the production process and readjustment after purge cleaning.

In addition, in the case of a resin composition for purging mixed with cross-linked polyethylene, since the cross-linked polyethylene is a super macromolecule, it may clog the screen of the extruder or mix into the product, which has an adverse effect, particularly on extrusion coating. It is difficult to use for wire coating coating.

[Means for Solving the Problems] The present inventors have conducted intensive studies in order to solve these drawbacks, and as a result, by using a special silicone oil composite,
Even at a resin temperature of 50 ° C, the cleaning effect inside the system is high,
The inventors have invented a resin composition for purging which minimizes generation of smoke, odor and deterioration of resin.

That is, the object of the present invention has been attained by a thermoplastic composition for purging a plastic molding machine, which comprises an organopolysiloxane in a thermoplastic resin.

 Hereinafter, the present invention will be described in detail.

The organopolysiloxane used in the present invention has a general formula (Where R is a monovalent hydrocarbon group and a is the viscosity of the organopolysiloxane at 10 cps, 25 ° C to 100,000 cps, 25 ° C
Is a positive integer such that it is in the range of). Normally, the value of a which makes the viscosity of an organopolysiloxane equal to 10 cps is about 10, and 100,000
The value of a that approximates cps is about 2000.

Examples of the hydrocarbon group R in the above general formula include alkyl, aryl, aralkyl and the like. Examples of the alkyl include methyl, ethyl, propyl, butyl, octyl, decyl and the like. Examples of the aryl include phenyl and naphthyl. Examples of aralkyl include benzyl, phenylethyl and the like, and a mixture of any of these may be used.

As organopolysiloxanes as slip agents, higher alkyl polysiloxanes, alkyl phenyl polysiloxanes, alkyl phenethyl polysiloxanes, diphenyl polysiloxanes, and the like have good compatibility and kneading properties with polyethylene and excellent heat resistance.

Furthermore, as an organopolysiloxane which effectively acts on the problem to be solved by the present invention, its viscosity is 10 cps (2
5 ° C) to 100,000 cps (25 ° C). 10cps (25
If the viscosity is lower than (° C), kneading into the thermoplastic resin becomes uneven, and if the viscosity is higher than 100,000 cps (25 ° C), it takes time to switch from purge cleaning to remanufacturing in the low-temperature barrel section. Not preferred.

The addition amount of these organopolysiloxanes is effectively 1 to 30 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the thermoplastic resin. If the amount is less than 1 part by weight, the slip property is insufficient, and if it is more than 30 parts by weight, kneading and extrusion become difficult.

The resin composition for purging a plastic molding machine according to the present invention may contain an inorganic filler, an antioxidant, and the like in addition to the organopolysiloxane.

As the inorganic filler, an inorganic compound such as calcium carbonate, silicon dioxide, titanium dioxide, talc, superfloss, and alumina oxide is used, but the average particle size is 10 μm because the screw and the die lip of the extruder are not damaged by abrasion.
The following are desirable: The addition amount can be 5 to 130 parts by weight, preferably 8 to 80 parts by weight, based on 100 parts by weight of the thermoplastic resin. If the amount is more than 130 parts by weight, it becomes difficult to add and disperse the resin in the resin having a low melt index, and the load on the extruder increases. If the amount is less than 5 parts by weight, the effect of physically removing the remaining adhered resin in the system is reduced.

Antioxidants also decompose slowly at temperatures above 250 ° C and must be selected for those with low volatility. Examples of the type include p-phenylenediamines such as N, N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and 2,2,4-
Trimethyl-1,2-dihydroquinone, 6-ethoxy-2,
Quinolines such as 2,4-trityl-1,2 dihydroquinoline,
2,6-di-t-butyl-4-methylphenol, n-octadecyl-3- (4'-hydroxy-3 ', 5'-di-
monophenols such as t-butylphenyl) propionate; 2,2'-methylene-bis- (4-methyl-6-t
-Butylphenol), 2,2'-thiodiethylenebis-
[3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4- (Hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′,
5'-di-t-butyl-4'-hydroxyphenyl) propionate] bis, trispolyphenols such as methane, 4,4'-thiobis- (6-t-butyl-3-methylphenol, 4,4'- Thiobis (6-t-butyl-o-
Thiobisphenols such as cresol), organic phosphoric acids such as tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylenediphosphonite, and organic phosphorous acid such as distearylpentaerythritol-diphosphite Esters, antioxidants selected from isocyanuric acids such as 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid alone or in combination of two or more. It is effective and desirable to add one to 0.001 to 6 parts by weight based on 100 parts by weight of the thermoplastic resin. With less than 0.001 part by weight, the effect of adding the antioxidant is not seen. There is no particular problem if the amount is more than 6 parts by weight, but the effect proportional to the added amount cannot be obtained, and the economical maximum amount is preferably 6 parts by weight or less.

Other additives include an antistatic agent, an ultraviolet absorber,
In addition, a heat-resistant organic pigment which can be used in place of or in combination with the inorganic filler is mentioned, and is not limited as long as the purge cleaning effect is not impaired.

The thermoplastic resin used in the present invention has a melt index (same as MI) to enhance the purge cleaning effect
The effect is smaller as (JIS K-6760) is smaller. Needless to say, it is better to select the resin in consideration of the viscosity of the resin depending on the motor capacity of the molding machine and the processing temperature to be purged and the melt index of the resin used in the next step. Among them, a resin having a melt index of 0.3 to 5 is desirable. 250 ℃
When the melt index is more than 5, the extrusion discharge pressure becomes small, the pipe wall frictional force becomes small, and the purging effect becomes poor. The melt index is
If it is smaller than 0.3, the motor load increases and the addition of an inorganic filler becomes difficult.

In addition, as the type of the thermoplastic resin used in the present invention,
Any type can be used as long as it melts at 250 ° C and exhibits fluidity, but it is preferably a thermoplastic resin of the same type as the resin produced by a plastic molding machine. Switching from cleaning to production again can be done in a short time and the machine can be adjusted with simple operations.
Particularly preferred. Examples of the thermoplastic resin include polyolefin, polystyrene, AS, ABS, polycarbonate, polyamide, and polyester resin. Moreover, polyolefin resins are preferred in consideration of the purging effect of the resin, the dispersion of the organopolysiloxane and the inorganic filler, the ease of handling, the economics, the mutual compatibility, the kneading properties, etc.
Overall, polyethylene is used as the most preferred resin.

[Action] The resin composition for purging of a plastic molding machine according to the present invention comprises a thermoplastic resin containing an organopolysiloxane, and a thermoplastic resin composition for purging on an inner wall surface heated to a temperature of 250 ° C. or more by a slip effect. The sticking is prevented, there is no stickiness due to stagnation, and the thermoplastic resin composition for purging is quickly extruded out of the system while cleaning the wall surface. Further, since the organopolysiloxane itself has higher heat resistance than a lubricant such as a fatty acid metal salt which has been conventionally used, thermal decomposition is small, and smoke and malodor are suppressed.

[Examples] Next, the present invention will be described with reference to Examples.

Table 1 summarizes the resin compositions for purging and evaluation results of Examples-1 to 24 and Comparative Examples-1 to 7. The numerical values in the table represent parts by weight of the substances used.

Example-1 A T-die extruder with 65 mmφ and L / D = 28 was set to a resin temperature of 300 ° C., and 25 kg of a resin colored with TiO ₂ was poured. Thereafter, 100 parts by weight of LDPE (MI = 1), 5 parts by weight of methylphenylpolysiloxane (400 cps, 25 ° C.) and an antioxidant n-octadecyl-3- (4′-hydroxy-3 ′, 5'-Di-t-butylphenyl) propionate [AO-1] 0.5 parts by weight and 15 parts by weight of inorganic filler are compounded into a uniform pellet foam, extruded at a screw rotation speed of 100 rpm, foaming and fuming properties. , Heat resistance, odor and purge effect were evaluated by sensory inspection such as visual observation.

In Example-1, the kneading with Banbury was easy, and the prevention of smoking, smell and foaming was greatly improved.

Example 2 Methylphenylpolysiloxane (400 cps, 25 ° C.)
A compound was prepared and evaluated in the same manner as in Example 1, except that the weight was reduced from 3 parts by weight to 3 parts by weight. Example-1
As in the case of the above, a great improvement was observed in the foaming, fuming, odor and purging effects.

Example 3 The antioxidant was tetrakis- [methylene-3- (3 ',
5'-Di-t-butyl-4'-hydroxyphenyl) propionate] [AO-2], and the evaluation was conducted in the same manner as in Example-2. In this case, too, similar to Examples 1 and 2, a great improvement was observed in the prevention of foaming, smoking and odor.

Example 4 The antioxidant was tetrakis- [methylene-3- (3 ',
5'-di-t-butyl-4'-hydroxyphenyl) propionate] [AO-2] and tetrakis (2,4-di-t
-Butylphenyl) 4,4'-biphenylenediphosphonite [AO-3], and the same evaluation as in Example 2 was performed. The heat resistance was further improved as compared with Example-2, and the purging effect and the prevention of smoking and odor were greatly improved.

Example-5 The same antioxidant as in Example-4 was increased from 0.5 parts by weight to 0.8 parts by weight using LDPE having a melt index of 3,
Evaluation was performed in the same manner as in Example-2. Foaming, fuming, smell,
Although a great improvement in heat resistance is seen, the purging effect is slightly larger with LDPE having a melt index of 1.

Example -6 Using LDPE having a melt index of 8, an antioxidant,
1,3,5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene [AO-4] was added, and evaluation was performed in the same manner as in Example-2. went. Example-5
The purge effect is greater with LDPE with a melt index of 3 at the time of.

However, other improvements such as foaming, smoking, and odor are extremely large.

Examples 7 to 9 Methylphenylpolysiloxane having a viscosity (degree of polymerization) of 30
The composition was evaluated in the same manner as in Example 4 instead of those of cps and 5000 cps, but foaming, fuming, smell, heat resistance and purging effect were greatly improved as in Example 4.

Examples 10 to 13 Instead of methylphenylpolysiloxane, evaluation was performed using methylphenethylpolysiloxane (400 cps, 100 cps, 10,000 cps) and dimethylpolysiloxane (100 cps), but foaming and smoking were performed in the same manner as in Example-4.・ Odor, heat resistance and purging effect have been greatly improved.

Comparative Example-1 When the addition of the organopolysiloxane was 0 and the addition of oleic amide as the slip agent caused a large amount of smoke and foaming, it did not function as a purge resin at high temperatures.

Comparative Example 2 If the methylphenylpolysiloxane and the antioxidant in the composition of Example 1 were not added, the resin would be deteriorated and the purging effect would be worsened.

Comparative Examples -3 to 6 Addition of slip agents such as oleic amide, erucamide and polyethylene wax, or glycerol monostearate instead of organopolysiloxane resulted in decomposition smoke and no improvement was observed.

Comparative Example-7 Of the composition of Comparative Example-3, without adding an inorganic filler
The compound consisting of LDPE, oleic acid amide and antioxidant had almost no purging effect for cleaning the seizure on the tube wall.

Examples 14 to 15 Instead of dimethylpolysiloxane having a viscosity of 100 cps in Example-13, 10 cps in Example-14 and 100,000 cp in Example-15.
Evaluation was performed using s-dimethylpolysiloxane, and it was proved that the effects of the present invention were exerted.

Examples 16 to 18 In place of 3 parts by weight of the methylphenylpolysiloxane used in Example 4, 1 part by weight in Example 16 and Example 1 were used.
Evaluation was performed using 20 parts by weight for 17 and 30 parts by weight for Example-18, and it was demonstrated that the effects of the present invention were exerted.

Examples -19 to 22 Instead of using 15 parts by weight of the inorganic filler of Example 4,
The evaluation was performed using 5 parts by weight in Example-19, 50 parts by weight in Example 20, 100 parts by weight in Example-21, and 130 parts by weight in Example-22. It was proven that

Examples 23 to 24 Evaluation was made using 0.001 part by weight in Example 23 and 6 parts by weight in Example 24 instead of using 0.5 part by weight of the antioxidant [AO-1] of Example-2. It was demonstrated that the effect of the present invention was exerted.

[Effect of the Invention] As can be seen from the examples, the thermoplastic resin composition for purging a plastic molding machine containing an organopolysiloxane is used in purging and cleaning of a plastic molding machine for 250 minutes.
Even at a high resin temperature of not less than ° C, workability such as smoke, foaming, and offensive odor was improved, and an excellent purging effect was obtained.

Claims (7)

(57) [Claims] 1. A thermoplastic resin composition for purging a plastic molding machine, wherein the thermoplastic resin contains an organopolysiloxane. 2. An organopolysiloxane of the general formula (Where R is a monovalent hydrocarbon group and a is the viscosity of the organopolysiloxane at 10 cps, 25 ° C to 100,000 cps, 25 ° C
(1) The thermoplastic resin composition for purging a plastic molding machine according to (1). 3. The thermoplastic resin composition for purging a plastic molding machine according to claim 1, wherein the organopolysiloxane is contained in an amount of 1 to 30 parts by weight based on 100 parts by weight of the thermoplastic resin. 4. The thermoplastic resin composition for purging a plastic molding machine according to claim 3, further comprising 5 to 130 parts by weight of an inorganic filler based on 100 parts by weight of the thermoplastic resin. 5. The thermoplastic resin composition for purging a plastic molding machine according to claim 3, further comprising 0.001 to 6 parts by weight of an antioxidant based on 100 parts by weight of the thermoplastic resin. 6. The thermoplastic resin composition for purging a plastic molding machine according to claim 1, wherein the thermoplastic resin is a thermoplastic resin of the same type as the plastic to be purged. 7. The thermoplastic resin composition for purging a plastic molding machine according to claim 1, wherein the thermoplastic resin is polyethylene.