CN108219448B

CN108219448B - Thermoplastic resin composition

Info

Publication number: CN108219448B
Application number: CN201810002876.8A
Authority: CN
Inventors: 傅李丹; 丁广军; 卜扬帆; 陈勇伟; 张光辉; 周永松
Original assignee: Hangzhou Bensong New Materials Technology Co ltd
Current assignee: Hangzhou Bensong New Materials Technology Co ltd
Priority date: 2018-01-02
Filing date: 2018-01-02
Publication date: 2021-02-02
Anticipated expiration: 2038-01-02
Also published as: CN108219448A

Abstract

The invention discloses a thermoplastic resin composition, which comprises raw material components of thermoplastic resin, a filler, a flame retardant and a weld mark improving agent, wherein the weld mark improving agent is anatase type and/or rutile type, and titanium dioxide subjected to organic and/or inorganic surface treatment and having the purity of more than or equal to 96 percent. The composition formula disclosed by the invention is suitable for various thermoplastic base materials, including engineering plastics such as polyester, polyamide and the like; the method is also particularly suitable for manufacturing plastic parts which need to adopt multi-sprue injection molding or plastic parts with inserts, cavities or wall thickness variation and more complex structures, and can obviously improve or even eliminate the welding marks on the parts.

Description

Thermoplastic resin composition

Technical Field

The invention relates to the technical field of modified thermoplastic resin compositions, in particular to a thermoplastic resin composition.

Background

In recent years, with the increasing demand for and the increasing quality of plastic products, higher and higher demands are being made on injection molding techniques. However, the injection molding has the defect that the injection molding cannot overcome the defect, namely when a product adopts a plurality of gates in the injection molding process or melts are separated and then converged due to insert, hollow and wall thickness change, welding marks are inevitably formed, and particularly the welding marks are more obvious when the plastic product is injection molded by selecting light-color materials modified by adding additives such as a filler, a flame retardant and the like. The existence of the weld marks directly influences the visual attractiveness of the plastic parts, particularly the visual attractiveness of the appearance parts, particularly in the industries of electronic appliances, automobile manufacturing and household appliances, is a key index, and the occurrence of the weld marks directly causes disqualification of products, so that the economic benefit of enterprises is seriously influenced. Therefore, in recent years, the analysis and improvement of the weld marks of injection molded products are receiving general attention, and the finding of a method for reducing or even eliminating the weld marks has very important practical significance for improving the quality of plastic products.

Currently, it is difficult for most injection-molded articles to completely eliminate weld marks. The common method basically starts from the aspects of injection molding part structure design, mold design, molding process parameter adjustment, injection molding part post-treatment and the like, and the welding mark is left at a concealed non-critical part so as to meet the requirement of the apparent quality of a product, but the risk of being identified as an unqualified product still exists. And from the material perspective, there is less research on mitigating or even eliminating weld marks through formulation optimization.

For example, chinese patent publication No. CN104592640A discloses a polyolefin reinforcing material and a method for preparing the same, in which an organic substance such as nonylphenol polyoxyethylene ether is used as a weld mark modifier to improve weld marks of polyolefin. However, the organic matters have poor temperature resistance, and are easily decomposed when used in engineering plastics with high processing temperature, such as polyamide, so that the effect of improving weld marks is not obvious.

Further, as disclosed in chinese patent publication No. CN104292622A, a polypropylene composition with low flow mark and low weld mark and a preparation method thereof are disclosed, wherein the polypropylene composition adopts hyperbranched polyethylene to improve the weld mark of the polypropylene composition. But the addition amount of the hyperbranched polyethylene is larger, the obvious improvement effect can be obtained; in addition, hyperbranched polyethylene has poor compatibility with resins such as polyamide and polyester, and the effect of improving weld marks in these resins is not significant.

It is clear that the solutions in the above patents are not suitable for improving weld marks of engineering plastics with high processing temperatures, such as polyamide and polyester.

Chinese patent publication No. CN106928697A discloses a nylon material, and a preparation method and application thereof, wherein a copolymer of nylon 6 and long-chain nylon is used as a resin matrix, and a glass fiber, which is a special reinforcing material, is used to eliminate injection molding weld marks of the nylon material. The reinforcing material in the composition is only glass fiber, the type is single, and the content cannot exceed 30 percent; and the cost of the copolymer of nylon 6 and long-chain nylon is higher than that of PA6, and the copolymer is not easy to obtain. Therefore, this method is difficult to spread widely for composition formulations where cost reduction by adding a large amount of reinforcing material is desired.

Disclosure of Invention

The invention provides a thermoplastic resin composition formula aiming at the problems in the prior art, which is suitable for various thermoplastic base materials, including engineering plastics such as polyester, polyamide and the like. The formula is also particularly suitable for manufacturing plastic parts which need to adopt multi-sprue injection molding, or plastic parts with inserts, cavities or wall thickness variation and more complex structures, and can obviously improve or even eliminate weld marks.

The specific technical scheme is as follows:

a thermoplastic resin composition comprises the following raw material components in percentage by weight:

the weld mark improving agent is titanium dioxide, is anatase type and/or rutile type, and is selected from titanium dioxide with purity more than or equal to 96% and subjected to organic and/or inorganic surface treatment.

Titanium dioxide, commonly known as titanium dioxide, is currently recognized in the plastics industry as a white pigment to improve the whiteness of materials. The inventor of the invention finds that the addition of titanium dioxide can improve the weld mark defect on the surface of the plastic product, and the weld mark defect can be obviously reduced or eliminated to be unidentifiable by naked eyes under the condition of extremely small dosage (0.5 weight percent). The other white pigment, zinc sulfide, commonly used in plastics has no effect of improving the weld mark after being tested.

Preferably, the titanium dioxide is rutile type titanium dioxide with the particle size less than or equal to 5 mu m. For example, the product is Ti-Pure available from Chemours corporation^TMTitanium dioxide of R-103. Tests show that the titanium dioxide of the mark has excellent dispersibility, wettability and rheological property in a thermoplastic resin melt, so that the titanium dioxide is easy to flow to a fusion interface where the melt is converged when a plastic product is processed and formed, thereby reducing or even eliminating the weld marks on the product.

The titanium dioxide can be directly titanium dioxide powder or can be added in a master batch form, and the master batch carrier can be thermoplastic resin, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene or ethylene-vinyl acetate copolymer and the like.

Preferably, the thermoplastic resin is at least one selected from the group consisting of polyamide, polyester, polypropylene and polyethylene.

Preferably, the filler is at least one selected from the group consisting of glass fiber, carbon fiber, glass bead, glass powder, wollastonite, talc, mica, calcium carbonate, fine silica powder, kaolin, clay, silica, alumina and magnesium hydroxide.

Preferably, the flame retardant is at least one selected from melamine cyanurate, melamine polyphosphate, aluminum diethylphosphinate, red phosphorus flame retardant masterbatch, decabromodiphenylethane, brominated polystyrene, antimony trioxide and zinc borate.

In addition to the above-mentioned preferred raw materials, it is further preferred that the thermoplastic resin composition comprises, as raw material components:

in addition, the thermoplastic resin composition may optionally comprise other processing aids, which may include, but are not limited to, one or more of antioxidants, heat stabilizers, lubricants, mold release agents, pigment additives, impact modifiers.

Tests show that when the titanium dioxide is not added into a thermoplastic resin system containing functional additives such as a filler, a flame retardant and the like, the weld mark is very obvious and even serious; and after a small amount of titanium dioxide is added, the welding mark is obviously improved, and even eliminated. Thus, the use of titanium dioxide has a very significant effect, especially in more complex formulated flame retardant, reinforced thermoplastic resin systems.

When a thermoplastic resin composition composed of the following raw materials is used,

further preferably, the thermoplastic resin is selected from the group consisting of polyamides; the flame retardant is selected from Melamine Cyanurate (MCA). The thermoplastic resin composition consisting of the special raw materials and special content is screened, and meanwhile, the flame-retardant effect of low welding marks and high glow wires is achieved. In the formula, titanium dioxide is used as a multifunctional auxiliary agent, and the functions of improving weld marks and improving the performance of a glow wire are exerted.

Tests show that in the formula of the composition, the addition of titanium dioxide can still remarkably improve and even eliminate weld marks; on the other hand, when MCA is used as a flame retardant, MCA can play a role of a glow wire synergist, the composition can withstand a glow wire test at 960 ℃ under the condition of a sample with the thickness of only 1.0mm, the glow wire time is obviously shortened, and the ignition self-extinguishing performance of the composition is obviously improved; further tests have found that there is an upper limit to the amount of titanium dioxide, above 10% by weight, that will not act as a glow wire synergist.

Preferably, the filler is at least one selected from glass fiber and inorganic filler;

the glass fiber is not subjected to surface treatment or is subjected to one or two of silane coupling agent, titanate coupling agent and aluminate coupling agent treatment; the inorganic filler is selected from at least one of wollastonite, mica, glass beads, calcium carbonate, kaolin and clay.

Still preferably, the thermoplastic resin composition comprises, in weight percent:

the invention also discloses a molded product comprising the thermoplastic resin composition.

Compared with the prior art, the invention has the following advantages:

(1) the invention adopts titanium dioxide which is low in price and easy to obtain as the weld mark improving agent, can well reduce or even eliminate the weld mark defect on the surface of the thermoplastic composition injection molding product, and can play a role in obviously improving under the condition of very low addition amount (0.5 weight percent) of the titanium dioxide.

(2) The titanium dioxide is applied to an MCA flame-retardant system, can be used as a weld mark improver to obviously improve the weld mark defect on the surface of an injection molding product, can also play a role of a glow wire synergist within a certain addition amount (less than 10 wt%), can obviously improve the performance of a glow wire and reduce the ignition risk of materials, and the prepared thermoplastic resin composition has the advantages of glow combustibility index (GWFI value) of 960/1.0, glow wire time of not more than 15s, excellent ignition self-extinguishing performance and safer material use.

Detailed Description

The present invention is further illustrated by the following specific examples, which are, however, not intended to limit the scope of the invention.

The following description will be made of the raw materials used in the examples and comparative examples, but not limited to these:

PA 6: basff corporation, trade Mark

B3K；

PA 66: dupont company, trade name

101L；

PET: japanese Tekken, Inc., brand TRN-8550 FF;

PBT: dupont company, trade name

6131；

Titanium dioxide: chemours corporation, brand Ti-Pure^TMR-103；

Zinc sulfide: huntsman corporation, HD-S;

wollastonite: NYCO Inc., trade name

4W；

Mica: LKAB corporation under the designation PW 30;

kaolin: KaMin corporation, brand Nylok 171;

magnesium hydroxide: HUBER Inc., trade Mark

H-5IV；

Glass fiber: chongqing International composite, 301HP (Polyamide), diameter 10 μm;

glass fiber: chongqing International composite, 303A (polyester), diameter 10 μm;

melamine cyanurate: basff corporation, trade Mark

MC50；

Brominated polystyrene: albemarle Corporation, trade Mark

HP-3010；

Antimony trioxide: yiyang Huachangby industry Co., Ltd, brand 99.5;

processing aid: pasteur, antioxidant 1010 and antioxidant 168, Lonza, lubricant PETS, the ratio of the three being 1:2: 3.

Examples 1 to 13

According to the material proportion in the table 1, the thermoplastic resin, the weld mark improving agent and other additive materials are uniformly mixed, and then a double-screw extruder is used for extruding and granulating, wherein the length-diameter ratio of the double-screw extruder is 40:1, the rotating speed of a screw is 280r/min, and the strands are subjected to water granulation. After drying the particles (usually drying in a vacuum drying oven at 80 ℃ for 5-8 h), forming standard sample bars of corresponding tests in an injection molding machine, and carrying out performance tests, wherein the test results are shown in table 1.

Comparative examples 1 to 13

The preparation method is the same as the example, the types and the use amounts of the raw material components are listed in table 2, and the performance test results are also shown in table 2.

In the above examples, the following properties of the prepared samples were tested according to the following methods:

(1) and (3) detecting a welding mark: the specimen size was 180X 120X 3mm with two 35X 35mm holes in the middle, a hole spacing of 70mm and a gate width of 4 mm. The weld marks on the surface of the sample were visually observed with the naked eye.

(2) Glow wire time (960/1.0, s) test: the specimens have dimensions of 90mm by 1.0mm and a glow wire temperature of 960 ℃ and are tested according to the national standard GB/T5169.12, the maximum duration of the flameless and/or flameless combustion of the test specimen being recorded after the top of the glow wire has been removed from the test specimen.

Remarking: glow wire times of more than 30 seconds indicate failure to pass the 960 c glow wire, and shorter glow wire times indicate lower risk of fire.

(3) And (3) testing the flame retardant grade: the test specimen size was 125 mm. times.13 mm. times.1.6 mm, and the test was carried out in accordance with UL-94 standard.

(4) And (3) detecting the whitening of the pouring gate: the mould size is 180X 120X 3mm, the middle has two 35X 35mm holes, the hole interval is 70mm, and the gate width is 4 mm. The appearance of the specimen gate was visually observed with the naked eye. TABLE 1

TABLE 2

As can be seen from a comparison of the results of examples 1 to 13 of Table 1 and comparative examples 1 to 13 of Table 2: the present invention can significantly improve weld mark appearance defects of thermoplastic resin compositions by adding a suitable amount of titanium dioxide to the thermoplastic resin compositions. The weld mark defect can be remarkably reduced by adding 0.5 wt% of titanium dioxide (example 3 and comparative examples 2 and 3), and when the amount of titanium dioxide is more than or equal to 1 wt%, the weld mark defect on the surface of the product can not be seen by naked eyes (example 1 and comparative example 1, example 4 and comparative example 2, example 7 and comparative example 6, example 12 and comparative example 12). And the pigment zinc sulfide is used for replacing titanium dioxide or no titanium dioxide is added in a system in which hydrogen sulfide exists (examples 5-6 and comparative examples 4-5, example 7 and comparative example 6), the weld mark defect on the surface of the product is obvious.

Meanwhile, the invention also surprisingly discovers that by adding a proper amount (less than 10 weight percent) of titanium dioxide into the MCA flame-retardant system, the invention not only can obviously improve the weld mark defect on the surface of the product, but also can play a role of a glow wire synergist, can obviously reduce the ignition risk of the thermoplastic resin composition, can reduce the time (960/1.0, s) of the glow wire from 35s to 55s to within 15s, even less than 5s (examples 8 and comparative examples 7 to 8, examples 9 and 9, examples 11 and 12, examples 13 and 13), has high material use safety, and can solve the problem of whitening of the sprue on the surface of the product, and the use amount of the titanium dioxide is more than or equal to 10 weight percent, so that the invention does not play a role in reducing the ignition risk of the material (examples 9 and 10 to 11).

Although the above embodiments have described the design idea of the present invention in more detail, these descriptions are only simple descriptions of the design idea of the present invention, and are not limitations of the design idea of the present invention, and any combination, addition, or modification without departing from the design idea of the present invention falls within the protection scope of the present invention.

Claims

1. Use of titanium dioxide for improving glow wire properties of a thermoplastic resin composition, characterized in that the thermoplastic resin composition comprises, in weight percent:

35-75% of thermoplastic resin;

15-60% of a filler;

5-30% of a flame retardant;

1-10% of titanium dioxide;

the sum of the contents of all the components is 100 percent;

wherein the titanium dioxide is rutile type, and is selected from titanium dioxide with purity not less than 96% and subjected to organic and/or inorganic surface treatment;

the thermoplastic resin is selected from polyamides;

the flame retardant is selected from melamine cyanurate.

2. The use according to claim 1, wherein the thermoplastic resin composition raw material components comprise, in weight percent:

40-65% of thermoplastic resin;

20-40% of a filler;

7-20% of a flame retardant;

2-6% of titanium dioxide.

3. Use according to claim 1 or 2, characterized in that the titanium dioxide is chosen from rutile titanium dioxide having a particle size of ≤ 5 μm.

4. Use according to claim 1 or 2, characterized in that the filler is selected from at least one of glass fibers, carbon fibers, glass microbeads, glass powder, wollastonite, talc, mica, calcium carbonate, silica micropowder, kaolin, clay, silica, alumina, magnesium hydroxide.

5. Use according to claim 2, characterized in that the filler is selected from at least one of glass fibers, inorganic fillers;

the glass fiber is not subjected to surface treatment or is subjected to one or two of silane coupling agent, titanate coupling agent and aluminate coupling agent treatment;

the inorganic filler is selected from at least one of wollastonite, mica, glass beads, calcium carbonate, kaolin and clay.

6. The use according to claim 1, wherein the raw material components of the thermoplastic resin composition further comprise other processing aids selected from one or more of antioxidants, heat stabilizers, lubricants, mold release agents, pigment additives, impact modifiers.