JP5642979B2 - Methacrylic resin composition - Google Patents

Description

  The present invention relates to a methacrylic resin composition suitable for heat welding.

  Methacrylic resin is characterized by its higher light transmittance, weather resistance and rigidity than other plastic transparent resins as a transparent resin, and is used for vehicle parts, lighting equipment, building materials, signboards, paintings, display windows, Used in a wide range of applications such as nameplates. It is also common to bond methacrylic resin moldings to give variations to the moldings. As the bonding method, heat-melt bonding by heating (hereinafter referred to as heat welding, hot plate welding, etc.) is widely used. It is used.

JP 2009-249528 A JP 2009-249529 A JP 2009-249530 A

However, there has been the following problem in heat-welding a molded body of methacrylic resin. That is, after applying a methacrylic resin molded body to a heated body, if the molded body is separated from the heated body, a thread-like polymer is attached to the molded body, resulting in poor welding. There was a problem. As a method for improving the stringing, there is a method of adding a fatty acid derivative or an aliphatic alcohol to a resin (Patent Documents 1 to 3). However, these methods merely improve the releasability of the resin when the molten resin is separated from the hot plate, and it cannot be said that the effect of suppressing stringing is sufficient. For this reason, it is necessary to take measures such as lowering the welding temperature, but if the welding temperature is low, the softening of the resin is not sufficient, so the welded part tends to come off, and sufficient welding strength cannot be obtained, This causes a problem that the time required for the process becomes longer. Further, in recent years, the welding apparatus has been modified, and instead of moving the molded body in the vertical direction as in the prior art, the molded body 3 is moved in the horizontal direction as shown in FIG. A device having a smaller moving distance of 5 may be used. When such an apparatus is used, the yarn pulled in the horizontal direction is likely to hang downward, which may affect the welding strength and appearance after that, and a method for further improving the yarn drawing has been demanded.
Therefore, the present invention relates to a methacrylic resin composition that is less likely to cause stringing in heat welding and can improve workability and welding strength.

As a result of diligent research to solve these problems, a resin composition in which a specific welding improver is added to a methacrylic resin having a specific composition solves problems such as stringing during molding. I found out that I can do it. That is, the present invention is as follows.
At least 1 selected from the group consisting of 80 to 99.5 wt% of methyl methacrylate monomer units, alkyl methacrylate having 2 to 18 carbon atoms in the alkyl group, and alkyl acrylate having 1 to 18 carbon atoms in the alkyl group. look-containing vinyl monomer units 0.5-20% seed, gate helper weight average molecular weight measured by permeation chromatography (GPC) is 60,000 to 230,000, the peak weight average molecular weight obtained from the GPC elution curve ( 1/5 of the weight average molecular weight component 7-30% contained a methacrylic resin composition mp) a [a], After producing the polymer (a), the polymer (a) and different The polymer (A) is mixed with the raw material composition mixture of the polymer (B) having a molecular weight to obtain a mixed solution, and the mixed solution is polymerized, or the polymer (A) and Polymers with different molecular weights and polymer (A) and (B) previously manufactured separately, a method of blending, any of the methacrylic resin composition prepared by the method of [A] 100 parts by weight In contrast,
A methacrylic resin composition comprising 0.05 to 0.5 parts by weight of the following welding improver [B].
Improving agent [B]: Aliphatic hydrocarbon having 12 to 24 carbon atoms.

  The methacrylic resin of the present invention is less likely to cause stringing at the time of heat welding, can improve the workability of heat welding, and has an effect that sufficient welding strength can be obtained after welding.

It is explanatory drawing regarding the GPC area of the methacrylic resin in this invention. The vertical axis of the graph shows RI (differential refraction) detection intensity (mV), the lower part of the horizontal axis of the graph shows elution time (min.), And the upper part shows the cumulative area area (%) with respect to the entire GPC area area. It is the figure which showed an example of the accumulation area area. It is the schematic which shows the position of 0-2% of accumulation area areas, and 98-100% of accumulation area areas on a GPC elution curve measurement graph. It is the schematic of the thread drawing length evaluation apparatus used by the present Example and the comparative example.

The present invention is described in further detail below. The methacrylic resin composition [A] in the present invention comprises methyl methacrylate and another vinyl monomer copolymerizable with methyl methacrylate.
Content in the methacrylic resin of a methyl methacrylate unit is 80-99.5 wt%. In order to suppress thermal decomposition of the resin, the methyl methacrylate unit needs to be 99.5 wt% or less. Moreover, 80 wt% or more is required from the viewpoint of heat resistance. By setting it within this range, it is possible to suppress distortion even after the molded product is placed in an environment such as high temperature, high humidity, or outdoors. More preferably, it is 90 wt% or more, and more preferably 95 wt% or more. If it is this range, generation | occurrence | production of the bubble which a monomer called foaming produced | generated by decomposition | disassembly of the resin called silver at the time of shaping | molding will be suppressed.

Other vinyl monomers copolymerizable with methyl methacrylate affect fluidity and heat resistance. Examples of other vinyl monomers copolymerizable with methyl methacrylate include the following.
Alkyl methacrylate having 2 to 18 carbon atoms in the alkyl group, alkyl acrylate having 1 to 18 carbon atoms in the alkyl group;
Α, β-unsaturated acids such as acrylic acid and methacrylic acid, unsaturated group-containing divalent carboxylic acids such as maleic acid, fumaric acid and itaconic acid, and alkyl esters thereof;
Aromatic vinyl compounds such as styrene, α-methylstyrene, styrene having a substituent on the benzene ring;
Vinyl cyanide compounds such as acrylonitrile and methacrylonitrile;
Maleic anhydride, maleimide, N-substituted maleimide and the like;
Ethylene glycol such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, etc. Esterified;
What esterified the hydroxyl group of two alcohols, such as neopentylglycol di (meth) acrylate and di (meth) acrylate, with acrylic acid or methacrylic acid;
Esterification of polyhydric alcohol derivatives such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid;
And polyfunctional monomers such as divinylbenzene.

These can be used alone or in combination of two or more. Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoints of light resistance, heat resistance, and fluidity. Used. Methyl acrylate, ethyl acrylate, and n-butyl acrylate are particularly preferable, and methyl acrylate is most preferable because it is easily available.
The content of other vinyl monomer units copolymerizable with methyl methacrylate needs to be 0.5 to 20 wt% with respect to the methacrylic resin. For the purpose of imparting fluidity, 0.5 wt% or more is necessary. Moreover, 20 wt% or less is required for the purpose of imparting heat resistance. In order to improve heat resistance, 10 wt% or less is preferable. In order to further improve fluidity and heat resistance, a more preferable range is 0.8 to 7 wt%. More preferably, it is 0.8-5 wt%.

The methacrylic resin composition [A] in the present invention has a weight average molecular weight of 60000-230,000 as measured by gel permeation chromatography (GPC). In order to maintain the mechanical strength, 60000 or more is necessary. In order to maintain fluidity, 230,000 or less is required. By making it within this range, the molding process becomes easy. Moreover, in order to improve fluidity | liquidity more, 70000-200000 or less are preferable.
The weight average molecular weight measured in the present invention is measured by gel permeation chromatography (GPC). A calibration curve is prepared in advance from the elution time and the weight average molecular weight using a monodispersed standard methacrylic resin having a known weight average molecular weight and available as a reagent, and an analytical gel column that elutes a high molecular weight component in advance. The molecular weight of each sample can be obtained from the obtained calibration curve.
In the present invention, the peak weight average molecular weight (Mp) refers to the weight average molecular weight showing a peak in the GPC elution curve. When there are a plurality of peaks in the GPC elution curve, the peak is indicated by the weight-average molecular weight having the largest abundance.

The weight average molecular weight component of 1/5 or less of Mp present in the methacrylic resin composition [A] in the present invention is important with respect to the mechanical strength of the resin and the distortion of the molded product. A weight average molecular weight component of 1/5 or less of Mp has a plasticizing effect. When the abundance of this component is in the range of 7 to 30% with respect to the methacrylic resin component, the effect of improving moldability and suppressing distortion of the molded product after molding can be obtained. 7% or more is necessary from the viewpoint of plasticizing effect and fluidity. If it is this range, the injection pressure at the time of shaping | molding can be suppressed, and the distortion of the molded article by residual distortion can be prevented. On the other hand, 30% or less is required from the viewpoints of heat resistance, suppression of cracks in the environmental test and distortion of the molded product, and strength. Preferably, it is 8-28%, More preferably, it is 10-27%. However, since the methacrylic resin component having a weight average molecular weight of 500 or less tends to cause a foam-like appearance defect called silver at the time of molding, it is preferably as small as possible.
The other vinyl monomer copolymerizable with methyl methacrylate preferably has a higher composition ratio in the high molecular weight component of the resulting methacrylic resin than the composition ratio in the low molecular weight component. This is because the fluidity can be further improved while maintaining the low occurrence rate of cracks and distortion of molded products and mechanical strength in heat resistance and environmental tests.

  Here, the area area in the GPC elution curve indicates the hatched portion shown in FIG. The specific method is as follows. First, point A and point B where the baseline automatically drawn by the measuring instrument and the GPC elution curve intersect with the GPC elution curve obtained from the elution time obtained by GPC measurement and the detected intensity by RI (differential refraction detector). Determine. Point A is a point where the GPC elution curve at the beginning of the elution time and the baseline intersect. Point B is a position where, as a general rule, the weight average molecular weight is 500 or more and the baseline and GPC elution curve intersect. If the weight average molecular weight does not intersect within the range of 500 or more, the value of RI detection intensity at the elution time when the weight average molecular weight is 500 is defined as point B. A hatched portion surrounded by the GPC elution curve between the points A and B and the line segment AB is an area in the GPC elution curve. This area is the area of the GPC elution curve. In this application, since a column eluted from a high molecular weight component is used, a high molecular weight component is observed at the beginning of the elution time, and a low molecular weight component is observed at the end of the elution time.

The cumulative area area (%) of the area area in the GPC elution curve is point 0 shown in FIG. 1 being 0%, which is the standard for the cumulative area area (%), toward the end of the elution time, and detection corresponding to each elution time. The view is that the intensity accumulates and an area area in the GPC elution curve is formed. A specific example of the accumulated area area is shown in FIG. In FIG. 2, a point on the baseline at a certain elution time is a point X, and a point on the GPC elution curve is a point Y. The ratio of the area surrounded by the curve AY, the line segment AX, and the line segment XY to the area area in the GPC elution curve is the value of the accumulated area area (%) at a certain elution time.
Let Mh (wt%) be the average composition ratio of other vinyl monomer units copolymerizable with methyl methacrylate in a methacrylic resin having a weight average molecular weight component in a cumulative area of 0 to 2%. On the other hand, the average composition ratio of other vinyl monomer units that can be copolymerized with methyl methacrylate in a methacrylic resin having a cumulative area of 98 to 100%, that is, a low molecular weight is defined as Ml (wt%). FIG. 3 shows a schematic diagram of positions on the measurement graph of the accumulated area area of 0 to 2% and 98 to 100%.

The values of Mh and Ml can be obtained by fractionating several times or several tens of times according to the column size based on the elution time obtained from GPC. The composition of the collected sample may be analyzed by a known pyrolysis gas chromatography method.
It is preferable that the relationship of the following formula [1] is established between Mh (wt%) and Ml (wt%).
(Mh−0.8) ≧ Ml ≧ 0 (1)
This indicates that the high molecular weight component has an average composition of 0.8 wt% or more of other vinyl monomer units copolymerizable with methyl methacrylate than the low molecular weight component. The low molecular weight component indicates that other vinyl monomers do not necessarily have to be copolymerized. The difference between Mh (wt%) and Ml (wt%) is preferably 0.8 wt% or more for the effect of improving fluidity. More preferably, it is 1.0 wt% or more.

The welding improver [B] used in the methacrylic resin composition in the present invention includes an aliphatic hydrocarbon having 12 to 24 carbon atoms, an aliphatic alcohol having 12 to 24 carbon atoms, and a fatty acid having 11 to 23 carbon atoms. Any one or more of monoester compounds of glycerin. By including the welding improver [B], defects during heat welding due to stringing or the like during secondary processing are suppressed.
This welding improver [B] needs to be contained in an amount of 0.05 parts by weight or more and 0.5 parts by weight or less with respect to 100 parts by weight of the methacrylic resin composition [A]. If it is 0.05 parts by weight or less, the effect of addition cannot be expected, and if it is 0.5 parts by weight or more, the heat resistance is lowered or silver or the like is generated during molding, which is not good. Preferably they are 0.08 weight part or more and 0.45 weight part or less, More preferably, they are 0.1 weight part or more and 0.4 weight part or less.

If the number of C is less than 12 as hydrocarbons, it is likely to become silver during molding. If the number of C is longer than 24, the effect of improving the stringing is low. Also, saturated aliphatic hydrocarbons are preferred over unsaturated aliphatic hydrocarbons. Specifically, they are dodecane, tetradecane, hexadecane, octadecane, and docosan, more preferably hexadecane, octadecane, and docosan, and these may be used alone or in combination.
As an aliphatic alcohol, when the number of C is shorter than 12, it is likely to become silver at the time of molding. If the number of C is longer than 24, the effect of improving the stringing is low. Also, saturated aliphatic alcohols are preferred over unsaturated aliphatic alcohols. Specifically, it is dodecanol, tetradecanol, hexadecanol, octadecanol, docosanol, more preferably hexadecanol, octadecanol, docosanol, and these may be used alone or in combination. May be.

  Monoesters are preferred for esters of fatty acids of C 11 to 23 and glycerin. However, in addition to the monoester, diesters and triesters included during production may be included. If the monoester purity is 80% or more, the performance as a monoester is exhibited. As fatty acid which performs ester reaction with glycerin, C11-C23 fatty acid is good. When C is shorter than 11, silver tends to be formed at the time of molding. If the number of C is longer than 24, the effect of improving the stringing is low. Moreover, as a fatty acid used as monoester, a saturated fatty acid is more preferable than an unsaturated fatty acid. Specifically, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, and docosanoic acid, more preferably hexadecanoic acid, octadecanoic acid, and docosanoic acid. These may be used alone or in combination. Also good. Of these, hydrocarbons having 12 to 22 carbon atoms are particularly preferable because they are readily available and have a high effect of improving stringing, and more specifically, docosane.

As described above, the low molecular weight component of 1/5 or less of Mp of the methacrylic resin composition [A] and the welding improver [B] component are compatible and bleed out to the adhesive interface and unevenly distributed on the adhesive interface. Thus, it is presumed that the adhesive strength is maintained even when welding is performed at a low temperature without causing stringing at the time of welding.
The above-mentioned methacrylic resin composition may further include dyes, pigments, heat stabilizers such as hindered phenols and phosphates, benzotriazoles, 2-hydroxybenzophenones, salicylic acid phenyl esters, and the like as necessary. Absorbent, phthalate ester, trimellitic ester, phosphoric ester, polyester, etc. plasticizer, polyolefin, etc., lubricant, polyether, polyether ester, polyether ester amide, alkyl sulfonic acid Organics such as salts, antistatic agents such as alkyl benzene sulfonates, flame retardants such as phosphorus, phosphorus / chlorine, phosphorus / bromine, and methyl methacrylate / styrene polymer beads to prevent glare from reflected light Light diffusing agent, barium sulfate, titanium oxide, calcium carbonate, talc Inorganic light diffusing agent may be used an acrylic rubber obtained by multistage polymerization as a reinforcing agent. When these additives are blended, it can be carried out by a known method. For example, a method in which an additive is dissolved in a monomer mixture in advance and polymerized is used.

As a method for producing methacrylic resins assembly formed product of the present invention is not particularly limited, and specific examples thereof include the following methods.
First, the manufacturing method of methacrylic resin composition [A] is demonstrated.
1. After producing the polymer (A) in advance, the polymer (A) is mixed with the raw material composition mixture of the polymer (B) having a molecular weight different from that of the polymer (A). A method of producing the mixture by polymerizing the mixture.
2. A method in which a polymer (B) having a molecular weight different from that of the polymer (A) and the polymer (A) is separately produced in advance and blended.

These methods relate to a method for producing two types of components having different molecular weight components. Regarding methods 1 and 2, polymers (C), polymers (D), etc. having different molecular weight compositions are also similar. The polymer (C), polymer (D), etc., produced by the procedure and having different molecular weight compositions may be further blended and melt kneaded with an extruder.
Preferably, the polymer (A) is produced, and the polymer (B) is produced in a state where the polymer (A) is present in the raw material composition mixture of the polymer (B). This is because the compositions of the polymer (A) and the polymer (B) can be easily controlled, the temperature rise due to polymerization heat generation during polymerization can be suppressed, and the viscosity in the system can be stably obtained. In this case, the raw material composition mixture of the polymer (B) may be in a state where the polymerization is partially started when (A) is added.
As the polymerization method of the methacrylic resin composition [A], any of bulk polymerization, solution polymerization, suspension polymerization method or emulsion polymerization method is preferable. More preferred are bulk polymerization, solution polymerization and suspension polymerization.

In the present invention, either the polymer (A) or the polymer (B) may have a high molecular weight, and either one may have a low molecular weight. The compositions of the polymer (A) and the polymer (B) are preferably different.
For example, if the content of the other vinyl monomer copolymerizable with methyl methacrylate is 0.8 to 20 wt% with respect to the methacrylic resin, the content of the polymer (A) and the polymer (B) It is preferred that the amounts are different.

Here, a method for producing a polymer (1) having a low molecular weight as the polymer (A) and producing a polymer (2) having a high molecular weight as the polymer (B) will be described.
First, a polymer (1) consisting of 80 to 100 wt% of a methyl methacrylate monomer and 0 to 20 wt% of a monomer composed of at least one other vinyl monomer copolymerizable with methyl methacrylate. First stage raw material is charged so as to obtain. At this time, it is preferable that the amount of the other vinyl monomer copolymerizable with methyl methacrylate is small, and it is not necessary to use it. The polymer (1) is adjusted so that the weight average weight measured by gel permeation chromatography is 5000 to 50000. By setting it to 5000 or more, the component in the methacrylic resin composition [A] having a weight average molecular weight of 500 or less that causes defects in molding is reduced, and the polymer (2) is reduced in the presence of the polymer (1). It is preferable because the molecular weight of the polymer (2) is stabilized during continuous production during production. Moreover, since the fluidity | liquidity of the obtained resin composition becomes good, it is good to set it as 50000 or less. More preferably, it is 5000-40000, More preferably, it is 8000-38000, It is 10000-36000, More preferably, it manufactures so that it may become 19000-38000.

Next, after producing the polymer (1), the polymer (2) is produced. At this time, a method for producing the polymer (2) in the presence of the polymer (1) is preferred. Furthermore, it is preferable to set a holding time for a certain time between the polymerization of the polymer (1) and the polymer (2).
Polymer (2) is a monomer composed of 80 to 99.5 wt% of methyl methacrylate monomer and 0.5 to 20 wt% of monomer composed of at least one other vinyl monomer copolymerizable with methyl methacrylate. The molecular weight of the copolymer is such that the weight average weight measured by gel permeation chromatography is 70000-250,000. The mechanical strength is preferably 70,000 or more from the viewpoint of fluidity, and 250,000 or less from the viewpoint of fluidity. More preferably, it is 70000-28000, More preferably, it is 75000-180000.
Moreover, it is preferable to produce the polymer (1) at a ratio of 5 to 40 wt% because an effect of improving fluidity can be obtained. Moreover, the mechanical strength of resin becomes a more preferable range as it is 40 wt% or less. More preferably, it is 5-35 wt%, More preferably, it is 10-30 wt%.

The ratio of the polymer (2) is preferably 95 to 60 wt%. In order to obtain the effect of improving fluidity, 95 wt% or less is preferable. 60 wt% or more is preferable from the viewpoint of the mechanical strength of the resin.
The composition ratio Mal (wt%) of other vinyl monomer units copolymerizable with methyl methacrylate of the polymer (1) and other vinyl monomers copolymerizable with methyl methacrylate of the polymer (2). It is preferable that the relationship of the formula (3) is established in the composition ratio Mah (wt%) of the monomer units.
(Mah-0.8) ≧ Mal ≧ 0 (3)
The composition ratios Mal and Mah can be determined by measuring each of the polymer (1) and the polymer (2) by a pyrolysis gas chromatography method. Since each value shows a value almost equal to the composition ratio used in the preparation, the composition ratio used in the preparation may be used.
The difference between Mah (wt%) and Mal (wt%) is preferably 0.8 wt% or more from the viewpoint of fluidity. If the polymer (1) having a high molecular weight contains a larger amount of other vinyl monomers copolymerizable with methyl methacrylate, the fluidity can be improved while maintaining heat resistance and mechanical strength. preferable.

As a polymerization initiator for producing the highly fluid methacrylic resin composition [A] of the present invention, the following general radical polymerization initiators can be used when free radical polymerization is used.
Di-t-butyl peroxide, lauroyl peroxide, dilauroyl peroxide, t-butylperoxy 2-ethylhexanoate, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane Peroxide systems such as 1,1-bis (t-butylperoxy) cyclohexane;
And azo series such as azobisisobutyronitrile, azobisisovaleronitrile, 1,1-azobis (1-cyclohexanecarbonitrile); and the like.
These may be used alone or in combination of two or more. A combination of these radical initiators and an appropriate reducing agent may be used as a redox initiator. These initiators are generally used in the range of 0.001 to 1 wt% with respect to the monomer mixture.

As a method for producing the methacrylic resin composition [A] , in the case of producing by a radical polymerization method, a chain generally used for adjusting the molecular weight of the polymer (A) and the polymer (B) is used. A transfer agent can be used. Examples of the chain transfer agent include n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, 2-ethylhexyl thioglycolate, ethylene glycol dithioglycolate, trimethylolpropane tris (thioglycolate), pentaerythritol tetrakis (thioglycolate). Etc.) are preferably used. Generally, it is used in the range of 0.001 to 1 wt% with respect to the monomer mixture. The chain transfer agent used for the polymer (A) and the polymer (B) may be the same or different. The amount of chain transfer agent of polymer (A) and polymer (B) is determined depending on the desired molecular weight.
The method for adding the welding improver [B] to the methacrylic resin composition [A] is not particularly limited, and is previously kneaded with the methacrylic resin composition [A] by dry blending and then kneaded using an extruder. The method may be used, and while the methacrylic resin composition [A] is melting, these materials may be put into an extruder and kneaded from the middle, or the methacrylic resin composition [A] is polymerized. It may be added to the raw material.

The methacrylic resin composition may be used alone or in combination with another resin. In the case of mixing, the mixture may be blended and heated and melted and mixed with an extruder, an injection molding machine or the like, or the pellets heated and mixed with an extruder may be used. The additives listed above may be blended and mixed at this time.
The methacrylic resin composition may be a combination of a plurality of methacrylic resin compositions of the present invention having different compositions, or may be combined with other known methacrylic resins. As a combination method, they may be used after blending or may be compounded once by an extruder and pelletized.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[material]
The raw materials used are as follows.
Methyl methacrylate: manufactured by Asahi Kasei Chemicals (2.5 ppm of 2,4-dimethyl-6-tert-butylphenol manufactured by Chugai Trading as a polymerization inhibitor)
Methyl acrylate: manufactured by Mitsubishi Chemical (14 ppm of 4-methoxyphenol manufactured by Kawaguchi Chemical Industry is added as a polymerization inhibitor)
n-octyl mercaptan: Arkema 2-ethylhexyl hexaenoate: Nippon Oil & Fats Tricalcium Phosphate: manufactured by Nippon Chemical Industry Co., Ltd. used as a suspending agent Calcium carbonate: Shiraishi Kogyo Co., Ltd. used as a suspending agent Sodium lauryl sulfate: Wako Pure Chemical Industries Manufactured, used as suspension aid Aliphatic hydrocarbons: All made by Wako Pure Chemical (1) Decane (C10)
(2) Docosan (C22)
(3) Hexacosan (C26)
Aliphatic alcohol (4) 1-decanol (C10): Aldrich (5) Stearyl alcohol (C18): Kao (6) Hexacosanol (C26): Aldrich fatty acid and glycerin monoester: All Aldrich (7 ) 1-decanoic acid monoglyceride (mono purity 83%)
(8) Stearic acid monoglyceride (mono purity 95%)
(9) Hexacosanoic acid monoglyceride (mono purity 82%)

[Measurement method]
[I. Measurement of resin composition and molecular weight]
1. Composition analysis of methacrylic resin The composition analysis of methacrylic resin was performed by pyrolysis gas chromatography and mass spectrometry.
Pyrolysis device: PY-2020D made by FRONTIER LAB
Column: DB-1 (length 30 m, inner diameter 0.25 mm, liquid phase thickness 0.25 μm)
Column temperature program: After holding at 40 ° C. for 5 minutes, the temperature is raised to 320 ° C. at a rate of 50 ° C./min, and 320 ° C. is held for 4.4 minutes
Pyrolysis furnace temperature: 550 ° C
Column inlet temperature: 320 ° C
Gas chromatography: Agilent GC6890
Carrier: pure nitrogen, flow rate 1.0 ml / min
Injection method: Split method (split ratio 1/200)
Detector: JEOL mass spectrometer Automass Sun
Detection method: Electron impact ionization method (ion source temperature: 240 ° C., interface temperature: 320 ° C.)
Sample: 10 μl of 10 cc chloroform solution of 0.1 g methacrylic resin
The sample was collected in a platinum sample cup for a pyrolysis apparatus, vacuum dried at 150 ° C. for 2 hours, and then placed in a pyrolysis furnace, and the composition analysis of the sample was performed under the above conditions. The composition ratio of the methacrylic resin was determined based on the peak area on total ion chromatography (TIC) of methyl methacrylate and methyl acrylate and the calibration curve of the following standard sample.
Preparation of standard sample for calibration curve: The ratio of methyl methacrylate and methyl acrylate is (methyl methacrylate / methyl acrylate) = (100% / 0%), (98% / 2%), (94% / 6% ), (90% / 10%) (80% / 20%) in total, 0.25% lauroyl peroxide and 0.25% n-octyl mercaptan were added to 50 g each. Each of these mixed solutions was put into a 100 cc glass ampule bottle, and the air was replaced with nitrogen and sealed. The glass ampoule bottle was placed in an 80 ° C. water bath for 3 hours and then in an oven at 150 ° C. for 2 hours. After cooling to room temperature, the glass was crushed and the methacrylic resin inside was taken out and subjected to composition analysis. A graph of (methyl acrylate area value) / (methyl methacrylate area value + methyl acrylate area value) and methyl acrylate charge ratio obtained by measurement of a standard sample for a calibration curve is used as a calibration curve. It was.

2. Apparatus for measuring and measuring the weight-average molecular weight of methacrylic resin: Nippon Analysis Industry Gel Permeation Chromatography (LC-908)
Column: 1 JAIGEL-4H and 2 JAIGEL-2H, in series connection This column elutes high molecular weight early, and low molecular weight elutes slowly.
Detector: RI (differential refraction) detector Detection sensitivity: 2.4 μV / sec
Sample: Chloroform 15 ml solution of 0.450 g methacrylic resin Injection amount: 3 ml
Developing solvent: chloroform, flow rate 3.3 ml / min
Under the above conditions, the RI detection intensity with respect to the elution time of the methacrylic resin was measured. The average molecular weight of the methacrylic resin was determined based on the area area in the GPC elution curve and the calibration curve.
The following 10 methacrylic resins (manufactured by EasiCal PM-1 Polymer Laboratories) having different molecular weights and known monodispersed weight average molecular weights were used as standard samples for calibration curves.

Weight average molecular weight
Standard sample 1 1,900,000
Standard sample 2 790,000
Standard sample 3 281,700
Standard sample 4 144,000
Standard sample 5 59,800
Standard sample 6 28,900
Standard sample 7 13,300
Standard sample 8 5,720
Standard sample 9 1,936
Standard sample 10 1,020

When the polymer (1) and the polymer (2) are mixed, the GPC elution curve of the polymer (1) alone is measured in advance to determine the weight average molecular weight, and the polymer (1) is present. GPC elution in which the polymer (1) and the polymer (2) are mixed by multiplying the GPC elution curve of the polymer (1) by the ratio (the charge ratio used in this application) By drawing from the curve, a GPC elution curve of the polymer (2) alone is obtained. From this, the weight average molecular weight of the polymer (2) was determined.
Further, the peak weight average molecular weight (Mp) in the GPC elution curve is determined from the GPC elution curve and the calibration curve.

The content of the weight average molecular weight component of 1/5 or less of Mp was determined as follows.
First, the area area in the GPC elution curve of the methacrylic resin composition [A] is determined. The area area in the GPC elution curve indicates the hatched portion shown in FIG. The specific method was determined as follows.
First, the GPC elution curve obtained from the GPC elution curve obtained from the GPC measurement and the detection intensity by RI (differential refraction detector) is crossed with the GPC elution curve by subtracting the automatically drawn baseline obtained by the measuring instrument. A and point B were defined. Point A is a point where the GPC elution curve at the beginning of the elution time and the baseline intersect. Point B is a position where, as a general rule, the weight average molecular weight is 500 or more and the base line and the elution curve intersect. If they do not intersect, point B is the value of the RI detection intensity at the elution time when the weight average molecular weight is 500. The hatched portion surrounded by the GPC elution curve and the base line between points A and B is the area in the GPC elution curve. This area is the area of the GPC elution curve. In the present application, since a column eluted from a high molecular weight component was used, a high molecular weight component was observed at the beginning of the elution time (point A side), and a low molecular weight component was observed at the end of the elution time (point B side).
The area area in the GPC elution curve was divided by the elution time corresponding to the weight average molecular weight of 1/5 of Mp, and the area area in the GPC elution curve corresponding to the weight average molecular weight component of 1/5 or less of Mp was determined. From the ratio of the area and the area area in the GPC elution curve, the ratio of the weight average molecular weight of 1/5 or less of Mp was determined.

3. Measurement of composition ratio of vinyl copolymer copolymerizable with methyl methacrylate in high molecular weight component and low molecular weight component of methacrylic resin composition [A] In this measurement, a molecular weight component having a cumulative area of 0 to 2%, The composition analysis of the molecular weight component which is 98 to 100% was performed. The cumulative area area (%) of the area area in the GPC elution curve is point 0 shown in FIG. 1 being 0%, which is the standard for the cumulative area area (%), toward the end of the elution time, and detection corresponding to each elution time. The view is that the intensity accumulates and an area area in the GPC elution curve is formed. A specific example of the accumulated area area is shown in FIG. In FIG. 3, a point on the baseline at a certain elution time is a point X, and a point on the GPC elution curve is a point Y. The ratio of the area surrounded by the curve AY, the line segment AX, and the line segment XY to the area area in the GPC elution curve is the value of the accumulated area area (%) at a certain elution time. FIG. 3 shows a schematic diagram of the positions on the measurement graph of the accumulated area areas 0 to 2% and 98 to 100% by performing the processing in this way.
A molecular weight component having a cumulative area of 0 to 2% and a molecular weight component being 98 to 100% were separated from the column based on the corresponding elution time, and the composition analysis was performed. Measurement and fractionation of each component are as follows. The same apparatus and conditions were used.
Perform the fractionation twice, and 10 μl of the fractionated sample is 1. The sample was collected in a platinum sample cup for a pyrolysis apparatus of the pyrolysis gas chromatography analysis and mass spectrometry method used in the above, and dried in a vacuum dryer at 100 ° C. for 40 minutes. 1. The composition of the methacrylic resin corresponding to the accumulated area area fractionated under the same conditions as above was determined.

4). Measurement of Addition of Hydrocarbon, Aliphatic Alcohol, Fatty Acid and Glycerol Monoester 0.2 g of resin was dissolved in 20 g of acetone, and 2 μl of the solution was quantitatively analyzed for stearyl alcohol by GC. GC was Shimadzu gas chromatography GC-1700, the column was TC-1, the column temperature was 50 ° C., the inj temperature was 250 ° C., and measured by the FID method. The carrier was nitrogen gas from a commercial cylinder.

[II. Measurement of practical properties]
1. This is a test for determining the relative fluidity based on the distance that the resin flows through a spiral cavity having a constant measurement cross-sectional area of the spiral length.
Injection molding machine: Toshiba Machine IS-100EN
Mold for measurement: Mold injection condition in which a groove having a depth of 2 mm and a width of 12.7 mm was dug into the Archimedes spiral shape from the center of the surface on the mold surface. Resin temperature: 250 ° C.
Mold temperature: 55 ° C
Injection pressure: 98 MPa
Injection time: 20 sec
Resin was injected into the center of the mold surface under the above conditions. After 40 seconds from the end of injection, the spiral molded product was taken out, and the length of the spiral portion was measured. This was used as an index for liquidity evaluation.
If silver appeared at the tip, it was defective and silver was generated.

2. Evaluation of welding temperature and thread drawing length In advance, using a Dynamelter M-70B manufactured by Meiki Co., Ltd., a mold temperature of 60 ° C., a molding temperature of 20 ° C., an injection speed of 70 MPa, and a holding pressure of 120 MPa are held for 20 seconds, a length of 250 mm, A strip test piece having a width of 13.5 mm and a thickness of 3.2 mm is formed and stored in a desiccator.
FIG. 4 shows a conceptual diagram of the evaluation apparatus.
First, the strip-shaped test piece 3 is fixed to the two movable jigs 4 and fixed to the rail 6. At this time, the 3 cm rail and the 100 cm movable jig 4 that runs on the rail were set so that the 13.5 mm × 3.2 mm portion overlapped in a facing manner. Thereafter, the movable jig 4 was moved to both sides.

On the rail 6 between the movable jigs 4, an aluminum heating solid 5 in which a rectangular parallelepiped surface having a side of 10 cm × 10 cm × 3 cm casted with a tungsten heater in which a temperature can be adjusted by varying a voltage is charged, The movable jig 4 was moved from both sides and pressed against the aluminum solid 5 at a pressure of 0.1 MPa for 10 seconds to melt both ends of the strip-shaped test piece 3. The melting temperature was determined by adjusting the temperature of a tungsten heater and measuring the surface temperature of the aluminum solid. The melting temperature was evaluated at two points: a normal molding temperature and a temperature 10 ° C. lower than the above temperature so that the stringing length and bending strength when molding at a low temperature to suppress stringing can be evaluated. .
Thereafter, the molded product was pulled away from the heated aluminum solid 5, the aluminum heated solid 5 was removed, and after 1 second, the melted product tips were pressed against each other with a pressing pressure of 0.2 MPa to perform thermal welding. This was used to measure the strength of the welded product described later.

Next, after the strip-shaped test piece 3 is brought into contact with the heated solid 5 made of SUS in the same manner, the test piece 3 is pulled away from the heated solid 5, and then the molded product is taken out. The length (string pulling length) of the longest thread-like resin that occurs when the sticking and leaving is measured. If there is a thread drawing length of 10 mm or more, this thread-like resin comes out on the surface of the heat-welded molded product, which becomes defective.
3. 1. Strength measurement of heat welded product The bending strength was measured based on JIS-K7171 for the heat-welded test piece obtained in (1). The molded product was evaluated by installing it so that the welded part was in the middle.

[IV. Polymerization of resin]
The manufacturing method of the methacrylic resin composition [A] of resin 1-7 is shown below.
Table 1 shows the blending amounts of the raw materials, and Table 2 shows the measurement results of the monomer charge composition and the polymer ratio and the weight average molecular weight of each polymer.

[Resin 1]
A 60 L reactor was charged with the blending amounts shown in Table 1 as raw materials for the polymer (1), and mixed by stirring. Suspension polymerization was carried out at a reaction temperature of 80 ° C. for 90 minutes. This polymer (1) was sampled and the polymerization average molecular weight was measured by GPC. The results are shown in Table 2.
Thereafter, the temperature was maintained at 80 ° C. for 60 minutes, and then the raw material of the polymer (2) was charged into the blending amount reactor shown in Table 1, followed by suspension polymerization at 80 ° C. for 90 minutes, followed by The temperature was raised at a rate of 1 / min, and aging was performed for 60 minutes to substantially complete the polymerization reaction. Next, it was cooled to 50 ° C., 20 wt% sulfuric acid was added to dissolve the suspending agent, the polymer was washed and dehydrated, and then dried to obtain a bead polymer. The average molecular weight of this bead polymer is measured by GPC, and based on the GPC elution curve of the polymer (1), the ratio of the polymer (1) is included and the GPC elution curve of the polymer on the beads is taken. From this, the GPC portion of the polymer (1) was removed, and the weight average molecular weight of the polymer (2) was determined.
The bead polymer thus obtained was extruded at 240 ° C. with a twin screw extruder and pelletized. The composition and molecular weight of the pellets were measured by pyrolysis gas chromatography analysis and gel permeation chromatography.

[Resin 2 to Resin 4]
Polymerization, measurement, and pelletization were carried out in the same manner as for the resin 1 except that the formulation shown in Table 1 was changed.
[Resin 5 to Resin 7]
The raw material of the polymer (1) is charged into a 60 L reactor at the blending amount shown in Table 1, suspended and polymerized at a reaction temperature of 80 ° C. for 150 minutes, and heated to 92 ° C. at a rate of 1 ° C./min. The polymerization was substantially completed after aging for 60 minutes. Next, the mixture was cooled to 50 ° C. and 20 wt% sulfuric acid was added to dissolve the suspending agent, followed by washing, dehydrating and drying treatment to obtain a bead polymer. This bead polymer was extruded at 240 ° C. with a twin screw extruder and pelletized. The composition and molecular weight of the pellets were measured by pyrolysis gas chromatography analysis and gel permeation chromatography.
The composition, molecular weight, peak molecular weight, and the like of the methacrylic resins of resins 1 to 7 obtained above were analyzed, and the results are shown in Table 3.

[Examples 1-6, Comparative Examples 1-14]
The welding improver [B] was added to the methacrylic resin composition [A] with the formulation shown in Table 4, and extrusion was carried out at 250 ° C. with a 30 mmφ twin-screw extruder to perform pelletization. The obtained pellets were evaluated for spiral flow length and string drawing length. The melting temperature at the time of evaluating the welding temperature and the stringing length was 250 ° C. and 240 ° C.
As shown in Table 4, the results of Examples 1 to 6 were shorter than that of Comparative Example 1 in that the stringiness length was shorter when the welding improver [B] was added. Further, Comparative Examples 2, 5, and 8 using a welding improver [B] with a monoester compound of hydrocarbon, aliphatic alcohol, fatty acid and glycerin having a small number of C are all evaluated when the spiral flow length is evaluated. In addition, the result was that silver was generated at the tip. On the contrary, in Comparative Examples 3, 4, 6, 7, 9, and 10 in which the number of C is long, the effect is not obtained in the yarn drawing length evaluation. When the methacrylic resin composition [A] having a low low molecular weight ratio is used as in Comparative Examples 11 and 12, the comparative example 11 has a very long yarn drawing length, and the comparative example 12 has a spiral flow length. In addition to being short, the thread drawing length was also long. Moreover, although the welding test was performed by lowering the temperature of heat welding from 250 ° C. to 240 ° C., in Examples 1 to 6, the results were satisfactory in both the yarn drawing length and the bending strength. In -12, even if the yarn drawing length was slightly shortened, the effect was not as good as in the examples, and there was also a problem in the strength of the welded part. Comparative Examples 13 and 14 are cases where the amount of the welding improver [B] is not appropriate. In Comparative Example 13 where the amount is less than 0.05 parts by weight, the stringing length is long and the welding strength is not good. Further, in Comparative Example 14 having more than 0.5 parts by weight, when the spiral flow length was evaluated, the result was that silver was generated at the tip.

[Example 7, Comparative Examples 15 to 17]
Using the composition as described in Table 4, a composition was obtained in the same manner as in Example 1 and evaluated.
In the case of Example 7 in which 0.1% of docosane was added as the welding improver [B], the yarn drawing length was greatly improved at the welding temperature of 280 ° C. as compared with Comparative Example 15 in which docosan was not added. Furthermore, in Comparative Example 16 and Comparative Example 17, a resin having a low low molecular weight ratio was used, and stearyl alcohol was added as a welding improver [B], so that both the spiral flow length and the thread drawing length were unpredictable. . Moreover, although the temperature of heat welding was lowered | hung and it welded at 270 degreeC, compared with Example 7, the result of comparative examples 15-17 became the result that the intensity | strength of a welding part was inadequate.

[Examples 8 and 9, Comparative Examples 18 and 19]
Using the composition as described in Table 4, a composition was obtained in the same manner as in Example 1 and evaluated.
In Examples 8 and 9, it was possible to use a plurality of types of welding improvers [B] in combination, but in Comparative Examples 18 and 19 in which no welding improver [B] was added, the yarn drawing length was long. In addition, even when the welding temperature was lowered, the result was that the strength of the welded portion was insufficient.

The methacrylic resin composition of the present invention is a display (device) window of a mobile phone, a liquid crystal monitor, a liquid crystal television, etc. whose appearance quality is very important, a light guide plate used for liquid crystal display, a front plate of a display device, a painting, etc. Forehead, exterior windows, signboards for display, carport roofs, display shelves, lighting fixture covers and gloves, secondary processing such as pressure forming, vacuum forming, blow molding, etc. It is useful for molded products that require Further, it is useful for producing molded products that require appearance quality, flow characteristics during molding, and moldability in secondary processing, such as optical components for vehicles such as tail lamps and headlamps.

1. GPC elution curve (a curve connecting RI detection intensity at each elution time)
2. Baseline 3. Test piece 4. 4. Operation jig Aluminum solid cast with variable voltage tungsten heater 6. Rail 7. Molded body tip

Claims (1)

80 to 99.5 wt% of methyl methacrylate monomer units and 2 to 1 carbon atoms of the alkyl group
8 alkyl methacrylate, and viewed including at least one vinyl monomer unit 0.5-20% carbon atoms in the alkyl group is selected from the group consisting of 1 to 18 alkyl acrylate, gate helper molecular weight distribution chromatography A methacrylic acid having a weight average molecular weight of 60000 to 230,000 measured by GRAPHIC (GPC) and containing 7 to 30% of a weight average molecular weight component of 1/5 or less of a peak weight average molecular weight (Mp) obtained from a GPC elution curve After producing the polymer (A), which is a resin composition [A] , the polymer (A) is mixed with a raw material composition mixture of a polymer (B) having a molecular weight different from that of the polymer (A). To obtain a mixed liquid and polymerize the mixed liquid, or separately produce a polymer (A) and a polymer (B) having a molecular weight different from that of the polymer (A). How to, to any of the methacrylic resin composition prepared by the process [A] 100 parts by weight of,
A methacrylic resin composition comprising 0.05 to 0.5 parts by weight of the following welding improver [B].
Improving agent [B]: Aliphatic hydrocarbon having 12 to 24 carbon atoms.

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